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Molina-Peñate E, Artola A, Sánchez A. Exploring biorefinery alternatives for biowaste valorization: a techno-economic assessment of enzymatic hydrolysis coupled with anaerobic digestion or solid-state fermentation for high-value bioproducts. Bioengineered 2024; 15:2307668. [PMID: 38265757 PMCID: PMC10810166 DOI: 10.1080/21655979.2024.2307668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 01/15/2024] [Indexed: 01/25/2024] Open
Abstract
Enzymatic hydrolysis of organic waste is gaining relevance as a complementary technology to conventional biological treatments. Moreover, biorefineries are emerging as a sustainable scenario to integrate waste valorization and high-value bioproducts production. However, their application on municipal solid waste is still limited. This study systematically evaluates the techno-economic feasibility of the conversion of the organic fraction of municipal solid waste (OFMSW) into high-value bioproducts through enzymatic hydrolysis. Two key variables are examined: (a) the source of the enzymes: commercial or on-site produced using OFMSW, and (b) the treatment of the solid hydrolyzate fraction: solid-state fermentation (SSF) for the production of biopesticides or anaerobic digestion for the production of energy. As a result, four different biorefinery scenarios are generated and compared in terms of profitability. Results showed that the most profitable scenario was to produce enzymes on-site and valorize the solid fraction via SSF, with an internal rate of return of 13%. This scenario led to higher profit margins (74%) and a reduced payback time (6 years), in contrast with commercial enzymes that led to an unprofitable biorefinery. Also, the simultaneous production of higher-value bioproducts and energy reduced the economic dependence of OFMSW treatment on policy instruments while remaining energetically self-sufficient. The profitability of the biorefinery scenarios evaluated was heavily dependent on the enzyme price and the efficiency of the anaerobic digestion process, highlighting the importance of cost-efficient enzyme production alternatives and high-quality OFMSW. This paper contributes to understanding the potential role of enzymes in future OFMSW biorefineries and offers economical insights on different configurations.
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Affiliation(s)
- Esther Molina-Peñate
- GICOM Research Group, Department of Chemical, Biological and Environmental Engineering, School of Engineering, Edifici Q, Universitat Autònoma de Barcelona, Barcelona, Bellaterra, Spain
| | - Adriana Artola
- GICOM Research Group, Department of Chemical, Biological and Environmental Engineering, School of Engineering, Edifici Q, Universitat Autònoma de Barcelona, Barcelona, Bellaterra, Spain
| | - Antoni Sánchez
- GICOM Research Group, Department of Chemical, Biological and Environmental Engineering, School of Engineering, Edifici Q, Universitat Autònoma de Barcelona, Barcelona, Bellaterra, Spain
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2
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Deng JJ, Peterson SD. Sensitivity of Phonation Onset Pressure to Vocal Fold Stiffness Distribution. J Biomech Eng 2024; 146:081003. [PMID: 38345603 DOI: 10.1115/1.4064718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Indexed: 03/22/2024]
Abstract
Phonation onset is characterized by the unstable growth of vocal fold (VF) vibrations that ultimately results in self-sustained oscillation and the production of modal voice. Motivated by histological studies, much research has focused on the role of the layered structure of the vocal folds in influencing phonation onset, wherein the outer "cover" layer is relatively soft and the inner "body" layer is relatively stiff. Recent research, however, suggests that the body-cover (BC) structure over-simplifies actual stiffness distributions by neglecting important spatial variations, such as inferior-superior (IS) and anterior-posterior gradients and smooth transitions in stiffness from one histological layer to another. Herein, we explore sensitivity of phonation onset to stiffness gradients and smoothness. By assuming no a priori stiffness distribution and considering a second-order Taylor series sensitivity analysis of phonation onset pressure with respect to stiffness, we find two general smooth stiffness distributions most strongly influence onset pressure: a smooth stiffness containing aspects of BC differences and IS gradients in the cover, which plays a role in minimizing onset pressure, and uniform increases in stiffness, which raise onset pressure and frequency. While the smooth stiffness change contains aspects qualitatively similar to layered BC distributions used in computational studies, smooth transitions in stiffness result in higher sensitivity of onset pressure than discrete layering. These two general stiffness distributions also provide a simple, low-dimensional, interpretation of how complex variations in VF stiffness affect onset pressure, enabling refined exploration of the effects of stiffness distributions on phonation onset.
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Affiliation(s)
- Jonathan J Deng
- Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - Sean D Peterson
- Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
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3
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De Santi O, Orellana M, Di Niro CA, Greco V. Response to Siddiqi et al. Addiction 2024; 119:1137-1138. [PMID: 38351609 DOI: 10.1111/add.16451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2024] [Accepted: 01/22/2024] [Indexed: 03/06/2024]
Affiliation(s)
- Omar De Santi
- Toxicology, Hospital Nacional Prof. Alejandro Posadas, Centro Nacional de Intoxicaciones (CNI), Buenos Aires, Argentina
| | - Marcelo Orellana
- Toxicology, Hospital Nacional Prof. Alejandro Posadas, Centro Nacional de Intoxicaciones (CNI), Buenos Aires, Argentina
| | - Cecilia Andrea Di Niro
- Cardiology, Hospital Municipal Central de San Isidro, Dr Melchor Posse, Buenos Aires, Argentina
| | - Vanina Greco
- Toxicology, Hospital Nacional Prof. Alejandro Posadas, Centro Nacional de Intoxicaciones (CNI), Buenos Aires, Argentina
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Konlan M, Abassawah Danquah B, Okyere E, Osman S, Amenyo Kessie J, Kobina Donkoh E. Global stability analysis and modelling onchocerciasis transmission dynamics with control measures. Infect Ecol Epidemiol 2024; 14:2347941. [PMID: 38736969 PMCID: PMC11086017 DOI: 10.1080/20008686.2024.2347941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Accepted: 04/22/2024] [Indexed: 05/14/2024] Open
Abstract
Background: Onchocerciasis infection is one of the neglected tropical diseases targeted for eradication by 2030. The disease is usually transmitted to humans through the bites of black flies. These black flies mostly breed near well-oxygenated fast-running water bodies. The disease is common in mostly remote agricultural villages near rivers and streams. Objective: In this study, a deterministic model describing the infection dynamics of human onchocerciasis disease with control measures is presented. Methods: We derived the model's reproductive number and used a stability theorem of a Metzler matrix to show that disease-free equilibrium is both locally and globally asymptotically stable whenever the reproductive number is less than one. Parameter contribution was conducted using sensitivity analysis. The model endemic equation is shown to be a cubic polynomial in the presence of infected immigrants and a quadratic form in their absence. Results: When the inflow of infected immigrants is null, the model endemic equation may admit a unique equilibrium if the reproductive number is greater than one, or admits multiple endemic equilibria if the reproductive number is less than unity. We carried out a sensitivity analysis to identify the significant parameters that contribute to onchocerciasis spread. Conclusion: Onchocerciasis disease can be eradicated if the importation of infected immigrants is properly monitored. The integration of the One Health concept in the public health system is key in tackling the emergence and spread of diseases.
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Affiliation(s)
- Musah Konlan
- Department of Mathematics and Statistics, University of Energy and Natural Resources, Sunyani, Ghana
| | - Baaba Abassawah Danquah
- Department of Mathematics and Statistics, University of Energy and Natural Resources, Sunyani, Ghana
| | - Eric Okyere
- Department of Mathematics and Statistics, University of Energy and Natural Resources, Sunyani, Ghana
| | - Shaibu Osman
- Department of Basic Sciences, University of Health and Allied Sciences, Ho, Ghana
| | - Justice Amenyo Kessie
- Department of Mathematics and Statistics, University of Energy and Natural Resources, Sunyani, Ghana
| | - Elvis Kobina Donkoh
- Department of Mathematics and Statistics, University of Energy and Natural Resources, Sunyani, Ghana
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Ssegonja R, Ljunggren M, Sampaio F, Tegelmo T, Theorell-Haglöw J. Economic evaluation of telemonitoring as a follow-up approach for patients with obstructive sleep apnea syndrome starting treatment with continuous positive airway pressure. J Sleep Res 2024; 33:e13968. [PMID: 37337981 DOI: 10.1111/jsr.13968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/15/2023] [Accepted: 06/05/2023] [Indexed: 06/21/2023]
Abstract
Telemonitoring of obstructive sleep apnea patients is increasingly being adopted though its cost-effectiveness evidence base is scanty. This study investigated whether telemonitoring is a cost-effective strategy compared with the standard follow-up in patients with obstructive sleep apnea who are starting continuous positive airway pressure treatment. In total, 167 obstructive sleep apnea patients were randomised into telemonitoring (n = 79) or standard follow-up (n = 88), initiated continuous positive airway pressure treatment, and were followed up for 6 months. The frequencies of healthcare contacts, related costs (in USD 2021 prices), treatment effect and compliance were compared between the follow-up approaches using generalised linear models. The cost effectiveness analysis was conducted from a healthcare perspective and the results presented as cost per avoided extra clinic visit. Additionally, patient satisfaction between the two approaches was explored. The analysis showed no baseline differences. At follow-up, there was no significant difference in treatment compliance, and the mean residual apnea-hypoapnea index. There was no difference in total visits, adjusted incidence rate ratio 0.87 (0.72-1.06). Participants in the telemonitoring arm made eight times more telephone visits, 8.10 (5.04-13.84), and about 73% fewer physical healthcare visits 0.27 (0.20-0.36). This translated into significantly lower total costs for the telemonitoring approach compared with standard follow-up, -192 USD (-346 to -41). The form of follow-up seemed to have no impact on the extent of patient satisfaction. These results demonstrate the telemonitoring of patients with obstructive sleep apnea initiating continuous positive airway pressure treatment as a cost saving strategy and can be argued as a potential worthy investment.
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Affiliation(s)
- Richard Ssegonja
- Department of Medical Sciences, Respiratory, Allergy- and Sleep Medicine Research Unit, Uppsala University, Uppsala, Sweden
- Department of Public Health and Caring Sciences, Uppsala University, Uppsala, Sweden
| | - Mirjam Ljunggren
- Department of Medical Sciences, Respiratory, Allergy- and Sleep Medicine Research Unit, Uppsala University, Uppsala, Sweden
| | - Filipa Sampaio
- Department of Public Health and Caring Sciences, Uppsala University, Uppsala, Sweden
| | - Tove Tegelmo
- Department of Medical Sciences, Respiratory, Allergy- and Sleep Medicine Research Unit, Uppsala University, Uppsala, Sweden
| | - Jenny Theorell-Haglöw
- Department of Medical Sciences, Respiratory, Allergy- and Sleep Medicine Research Unit, Uppsala University, Uppsala, Sweden
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Stadt MM, Layton AT. A modeling analysis of whole body potassium regulation on a high-potassium diet: proximal tubule and tubuloglomerular feedback effects. Am J Physiol Regul Integr Comp Physiol 2024; 326:R401-R415. [PMID: 38465401 DOI: 10.1152/ajpregu.00283.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 02/15/2024] [Accepted: 03/05/2024] [Indexed: 03/12/2024]
Abstract
Potassium (K+) is an essential electrolyte that plays a key role in many physiological processes, including mineralcorticoid action, systemic blood-pressure regulation, and hormone secretion and action. Indeed, maintaining K+ balance is critical for normal cell function, as too high or too low K+ levels can have serious and potentially deadly health consequences. K+ homeostasis is achieved by an intricate balance between the intracellular and extracellular fluid as well as balance between K+ intake and excretion. This is achieved via the coordinated actions of regulatory mechanisms such as the gastrointestinal feedforward effect, insulin and aldosterone upregulation of Na+-K+-ATPase uptake, and hormone and electrolyte impacts on renal K+ handling. We recently developed a mathematical model of whole body K+ regulation to unravel the individual impacts of these regulatory mechanisms. In this study, we extend our mathematical model to incorporate recent experimental findings that showed decreased fractional proximal tubule reabsorption under a high-K+ diet. We conducted model simulations and sensitivity analyses to investigate how these renal alterations impact whole body K+ regulation. Model predictions quantify the sensitivity of K+ regulation to various levels of proximal tubule K+ reabsorption adaptation and tubuloglomerular feedback. Our results suggest that the reduced proximal tubule K+ reabsorption under a high-K+ diet could achieve K+ balance in isolation, but the resulting tubuloglomerular feedback reduces filtration rate and thus K+ excretion.NEW & NOTEWORTHY Potassium homeostasis is maintained in the body by a complex system of regulatory mechanisms. This system, when healthy, maintains a small extracellular potassium concentration, despite large fluctuations of dietary potassium. The complexities of the system make this problem well suited for investigation with mathematical modeling. In this study, we extend our mathematical model to consider recent experimental results on renal potassium handling on a high potassium diet and investigate the impacts from a whole body perspective.
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Affiliation(s)
- Melissa M Stadt
- Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario, Canada
| | - Anita T Layton
- Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario, Canada
- Cheriton School of Computer Science, University of Waterloo, Waterloo, Ontario, Canada
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
- Department of Pharmacy, University of Waterloo, Waterloo, Ontario, Canada
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7
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Fairfax SR, Yang S. Distributional imputation for the analysis of censored recurrent events. Stat Med 2024. [PMID: 38684331 DOI: 10.1002/sim.10087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 03/29/2024] [Accepted: 04/13/2024] [Indexed: 05/02/2024]
Abstract
Longitudinal clinical trials for which recurrent events endpoints are of interest are commonly subject to missing event data. Primary analyses in such trials are often performed assuming events are missing at random, and sensitivity analyses are necessary to assess robustness of primary analysis conclusions to missing data assumptions. Control-based imputation is an attractive approach in superiority trials for imposing conservative assumptions on how data may be missing not at random. A popular approach to implementing control-based assumptions for recurrent events is multiple imputation (MI), but Rubin's variance estimator is often biased for the true sampling variability of the point estimator in the control-based setting. We propose distributional imputation (DI) with corresponding wild bootstrap variance estimation procedure for control-based sensitivity analyses of recurrent events. We apply control-based DI to a type I diabetes trial. In the application and simulation studies, DI produced more reasonable standard error estimates than MI with Rubin's combining rules in control-based sensitivity analyses of recurrent events.
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Affiliation(s)
- Sarah R Fairfax
- Department of Statistics, North Carolina State University, Raleigh, North Carolina, USA
| | - Shu Yang
- Department of Statistics, North Carolina State University, Raleigh, North Carolina, USA
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Pouwels XGLV, Kroeze K, van der Linden N, Kip MMA, Koffijberg H. Validating health economic models with the Probabilistic Analysis Check dashBOARD (PACBOARD). Value Health 2024:S1098-3015(24)02340-4. [PMID: 38641056 DOI: 10.1016/j.jval.2024.04.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 03/21/2024] [Accepted: 04/09/2024] [Indexed: 04/21/2024]
Abstract
OBJECTIVES Health economic (HE) models are often considered as "black boxes" because they are not publicly available and lack transparency, which prevents independent scrutiny of HE models. Additionally, validation efforts and validation status of HE models are not systematically reported. Methods to validate HE models in absence of their full underlying code are therefore urgently needed to improve health policy making.This study aimed to develop and test a generic dashboard to systematically explore the workings of HE models and validate their model parameters and outcomes. METHODS The Probabilistic Analysis Check dashBOARD (PACBOARD) was developed using insights from literature, health economists, and a data scientist.Functionalities of PACBOARD are 1) exploring and validating model parameters and outcomes using standardised validation tests and interactive plots, 2) visualising and investigating the relationship between model parameters and outcomes using metamodelling, and 3) predicting health economic outcomes using the fitted metamodel.To test PACBOARD, two mock HE models were developed and errors were introduced in these models, e.g. negative costs inputs, utility values exceeding 1. PACBOARD metamodelling predictions of incremental net monetary benefit were validated against the original model's outcomes. RESULTS PACBOARD automatically identified all errors introduced in the erroneous HE models. Metamodel predictions were accurate compared to the original model outcomes. CONCLUSIONS PACBOARD is a unique dashboard aiming at improving the feasibility and transparency of validation efforts of HE models. PACBOARD allows users to explore the working of HE models using metamodelling based on HE models' parameters and outcomes.
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Affiliation(s)
- Xavier G L V Pouwels
- Section of Health Technology & Services Research, Technical Medical Centre, Faculty of Behavioural, Management, and Social Sciences, University of Twente, the Netherlands, Overijssel, Enschede.
| | - Karel Kroeze
- Behavioural Data Science incubator, Faculty of Behavioural, Management, and Social Sciences, University of Twente, the Netherlands, Overijssel, Enschede
| | - Naomi van der Linden
- Section of Health Technology & Services Research, Technical Medical Centre, Faculty of Behavioural, Management, and Social Sciences, University of Twente, the Netherlands, Overijssel, Enschede; Institute for Health Systems Science, Faculty of Technology, Policy and Management, Delft University of Technology, the Netherlands, South Holland, Delft
| | - Michelle M A Kip
- Section of Health Technology & Services Research, Technical Medical Centre, Faculty of Behavioural, Management, and Social Sciences, University of Twente, the Netherlands, Overijssel, Enschede
| | - Hendrik Koffijberg
- Section of Health Technology & Services Research, Technical Medical Centre, Faculty of Behavioural, Management, and Social Sciences, University of Twente, the Netherlands, Overijssel, Enschede
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Li W, Zhou Q, Zhou L, Cao L, Zhu C, Dai Z, Lin S. Causal role of immune cell phenotypes in idiopathic sudden sensorineural hearing loss: a bi-directional Mendelian randomization study. Front Neurol 2024; 15:1368002. [PMID: 38694774 PMCID: PMC11061525 DOI: 10.3389/fneur.2024.1368002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 04/05/2024] [Indexed: 05/04/2024] Open
Abstract
Background A growing body of evidence suggests that immunological processes have a significant role in developing idiopathic sudden sensorineural hearing loss (SSHL). However, few studies have examined the association between immune cell phenotype and SSHL using Mendelian Randomization (MR). Methods The online genome-wide association studies (GWAS) database was used to compile data from GWAS covering 731 immunophenotypes and SSHL. Inverse variance weighted (IVW) analysis was primarily used for MR study, and single nucleotide polymorphisms (SNPs) associated with immunophenotypes served as dependent variables. A sensitivity study and the false discovery rate (FDR) correction were used to examine the MR hypothesis. In addition, the possibility of reverse causality between immunophenotype and SSHL was validated by reverse MR. Reverse MR was analyzed in a manner consistent with forward MR. Results After FDR correction and sensitivity analysis, we screened 7 immunophenotypes, including IgD+ CD38dim %lymphocyte (95% CI: 1.0019, 1.0742, p = 3.87 × 10-2, FDR = 1.15 × 10-2); Unsw mem AC (95% CI: 1.004, 1.2522, p = 4.23 × 10-2, FDR = 2.25 × 10-2); CD86+ myeloid DC AC (95% CI: 1.0083, 1.1147, p = 2.24 × 10-2, FDR = 4.27 × 10-2); CD33dim HLA DR- AC (95% CI: 1.0046, 1.0583, p = 2.12 × 10-2, FDR = 4.69 × 10-2); SSC-A on CD8br (95% CI: 1.0028, 1.1461, p = 4.12 × 10-2, FDR = 4.71 × 10-2); CD45RA- CD4+ %T cell (95% CI: 1.0036, 1.0503, p = 2.32 × 10-2, FDR = 4.82 × 10-2); DP (CD4+CD8+) AC (95% CI: 1.011, 1.2091, p = 2.78 × 10-2, FDR = 4.97 × 10-2). There was a strong causal relationship with SSHL onset, and the reliability of the results was verified. Furthermore, the immunological cell profile and SSHL did not appear to be closely associated, as shown by reverse MR analysis. Conclusion Our study provides more support for the current hypothesis that immunophenotypes and the pathophysiology of SSHL are closely associated. Further validation is needed to assess the role of these immunophenotypes in SSHL.
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Affiliation(s)
- Wanqing Li
- Department of Otolaryngology, Ruian People’s Hospital, The Third Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Qiang Zhou
- Department of Otolaryngology, Ruian People’s Hospital, The Third Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Linsa Zhou
- Department of Burns and Plastic Surgery, The Second Affiliated Hospital of Shantou University Medical College, Shantou, China
| | - Longhe Cao
- Department of Otolaryngology, Ruian People’s Hospital, The Third Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Chuansai Zhu
- Department of Otolaryngology, Ruian People’s Hospital, The Third Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Zhijian Dai
- Department of Otolaryngology, Ruian People’s Hospital, The Third Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Sen Lin
- Department of Otolaryngology, Ruian People’s Hospital, The Third Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
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Meng Z, Wang J, Lin L, Wu C. Sensitivity analysis with iterative outlier detection for systematic reviews and meta-analyses. Stat Med 2024; 43:1549-1563. [PMID: 38318993 PMCID: PMC10947935 DOI: 10.1002/sim.10008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 10/03/2023] [Accepted: 12/21/2023] [Indexed: 02/07/2024]
Abstract
Meta-analysis is a widely used tool for synthesizing results from multiple studies. The collected studies are deemed heterogeneous when they do not share a common underlying effect size; thus, the factors attributable to the heterogeneity need to be carefully considered. A critical problem in meta-analyses and systematic reviews is that outlying studies are frequently included, which can lead to invalid conclusions and affect the robustness of decision-making. Outliers may be caused by several factors such as study selection criteria, low study quality, small-study effects, and so on. Although outlier detection is well-studied in the statistical community, limited attention has been paid to meta-analysis. The conventional outlier detection method in meta-analysis is based on a leave-one-study-out procedure. However, when calculating a potentially outlying study's deviation, other outliers could substantially impact its result. This article proposes an iterative method to detect potential outliers, which reduces such an impact that could confound the detection. Furthermore, we adopt bagging to provide valid inference for sensitivity analyses of excluding outliers. Based on simulation studies, the proposed iterative method yields smaller bias and heterogeneity after performing a sensitivity analysis to remove the identified outliers. It also provides higher accuracy on outlier detection. Two case studies are used to illustrate the proposed method's real-world performance.
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Affiliation(s)
- Zhuo Meng
- Department of Statistics, College of Arts and Sciences, Florida State University, Tallahassee, FL, U.S.A
| | - Jingshen Wang
- Division of Biostatistics, School of Public Health, University of California, Berkeley, Berkeley, CA, U.S.A
| | - Lifeng Lin
- Department of Epidemiology and Biostatistics, Mel and Enid Zuckerman College of Public Health, The University of Arizona, Tucson, AZ, U.S.A
| | - Chong Wu
- Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, TX, U.S.A
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Fu C, Li M. Sensitivity Analysis of Influencing Factors and Two-Stage Prediction of Frost Resistance of Active-Admixture Recycled Concrete Based on Grey Theory-BPNN. Materials (Basel) 2024; 17:1805. [PMID: 38673162 PMCID: PMC11050828 DOI: 10.3390/ma17081805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 04/03/2024] [Accepted: 04/11/2024] [Indexed: 04/28/2024]
Abstract
Sensitivity analysis of influencing factors on frost resistance is carried out in this paper, and a two-stage neural network model based on grey theory and Back Propagation Neural Networks (BPNNs) is established for the sake of predicting the frost resistance of active-admixture recycled concrete quickly and accurately. Firstly, the influence degree of cement, water, sand, natural aggregate, recycled aggregate, mineral powder, fly ash, fiber and air-entraining agent on the frost resistance of active-admixture recycled-aggregate concrete was analyzed based on the grey system theory, and the primary and secondary relationships of various factors were effectively distinguished. Then, the input layer of the model was determined as cement, water, sand, recycled aggregate and air-entraining agent, and the output layer was the relative dynamic elastic modulus. A total of 120 datasets were collected from the experimental data of another author, and the relative dynamic elastic modulus was predicted using the two-stage BPNN prediction model proposed in this paper and compared with the BPNN prediction results. The results show that the proposed two-stage BPNN model, after removing less-sensitive parameters from the input layer, has better prediction accuracy and shorter run time than the BPNN model.
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Affiliation(s)
- Chun Fu
- School of Civil Engineering, Liaoning Petrochemical University, Fushun 113001, China
| | - Ming Li
- School of Civil Engineering, Shenyang Jianzhu University, Shenyang 110168, China;
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Aldila D, Dhanendra RP, Khoshnaw SHA, Wijayanti Puspita J, Kamalia PZ, Shahzad M. Understanding HIV/AIDS dynamics: insights from CD4+T cells, antiretroviral treatment, and country-specific analysis. Front Public Health 2024; 12:1324858. [PMID: 38665242 PMCID: PMC11043473 DOI: 10.3389/fpubh.2024.1324858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 03/14/2024] [Indexed: 04/28/2024] Open
Abstract
In this article, we present a mathematical model for human immunodeficiency virus (HIV)/Acquired immune deficiency syndrome (AIDS), taking into account the number of CD4+T cells and antiretroviral treatment. This model is developed based on the susceptible, infected, treated, AIDS (SITA) framework, wherein the infected and treated compartments are divided based on the number of CD4+T cells. Additionally, we consider the possibility of treatment failure, which can exacerbate the condition of the treated individual. Initially, we analyze a simplified HIV/AIDS model without differentiation between the infected and treated classes. Our findings reveal that the global stability of the HIV/AIDS-free equilibrium point is contingent upon the basic reproduction number being less than one. Furthermore, a bifurcation analysis demonstrates that our simplified model consistently exhibits a transcritical bifurcation at a reproduction number equal to one. In the complete model, we elucidate how the control reproduction number determines the stability of the HIV/AIDS-free equilibrium point. To align our model with the empirical data, we estimate its parameters using prevalence data from the top four countries affected by HIV/AIDS, namely, Eswatini, Lesotho, Botswana, and South Africa. We employ numerical simulations and conduct elasticity and sensitivity analyses to examine how our model parameters influence the control reproduction number and the dynamics of each model compartment. Our findings reveal that each country displays distinct sensitivities to the model parameters, implying the need for tailored strategies depending on the target country. Autonomous simulations highlight the potential of case detection and condom use in reducing HIV/AIDS prevalence. Furthermore, we identify that the quality of condoms plays a crucial role: with higher quality condoms, a smaller proportion of infected individuals need to use them for the potential eradication of HIV/AIDS from the population. In our optimal control simulations, we assess population behavior when control interventions are treated as time-dependent variables. Our analysis demonstrates that a combination of condom use and case detection, as time-dependent variables, can significantly curtail the spread of HIV while maintaining an optimal cost of intervention. Moreover, our cost-effectiveness analysis indicates that the condom use intervention alone emerges as the most cost-effective strategy, followed by a combination of case detection and condom use, and finally, case detection as a standalone strategy.
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Affiliation(s)
- Dipo Aldila
- Department of Mathematics, Universitas Indonesia, Depok, Indonesia
| | | | | | | | | | - Muhammad Shahzad
- Department of Mathematics and Statistics, The University of Haripur, Haripur, KP, Pakistan
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Wu R, Zhang X, Zhao J, Yi D, Gao F, Bao W. Population Viability Analysis on Chinese Goral Indicates an Extinction Risk for a Local Population in Beijing, China. Animals (Basel) 2024; 14:1126. [PMID: 38612364 PMCID: PMC11011114 DOI: 10.3390/ani14071126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 03/24/2024] [Accepted: 04/03/2024] [Indexed: 04/14/2024] Open
Abstract
The Chinese goral (Naemorhedus griseus) is identified as a vulnerable species on the Red List of China's Biodiversity and listed as a national second-class key protected wild animal in China. It is a representative flagship ungulate in Beijing. Its distribution range is fragmented and small populations are separated by dense infrastructures and tourism sites. Understanding its population status provides a foundation to plan effective conservation strategies. In this study, a population viability analysis was conducted with VORTEX (10.5.6.0) on a Chinese goral population in Beijing Yunmengshan Nature Reserve with the data collected by camera trapping and parameters referenced from other goral populations. The results show that this population will initially increase in the next 20 years and then decrease with a 32% probability of extinction risk. Supplementation with four adults, two females and two males, every 10 years would help minimize the extinction risk of this population. The results highlight the vital limiting factors for Chinese goral, including the initial population size, sex ratio at birth and mortality of infants (especially female infants). To improve the protection efficiency, detailed population parameters should be further acquired through continuous monitoring of this population. A thorough large-scale study should be carried out on other segregated goral populations in Beijing to facilitate the recovery of this endangered species.
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Affiliation(s)
- Rihan Wu
- National Engineering Research Center of Tree Breeding and Ecological Restoration, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, China; (R.W.); (F.G.)
| | - Xin Zhang
- Beijing Miyun District Yunmengshan Forest Management Unit, Beijing 101506, China; (X.Z.); (J.Z.); (D.Y.)
| | - Jianxi Zhao
- Beijing Miyun District Yunmengshan Forest Management Unit, Beijing 101506, China; (X.Z.); (J.Z.); (D.Y.)
| | - Deying Yi
- Beijing Miyun District Yunmengshan Forest Management Unit, Beijing 101506, China; (X.Z.); (J.Z.); (D.Y.)
| | - Fuli Gao
- National Engineering Research Center of Tree Breeding and Ecological Restoration, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, China; (R.W.); (F.G.)
| | - Weidong Bao
- National Engineering Research Center of Tree Breeding and Ecological Restoration, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, China; (R.W.); (F.G.)
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14
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Nguyen H, Schubert KE, Pohling C, Chang E, Yamamoto V, Zeng Y, Nie Y, Van Buskirk S, Schulte RW, Patel CB. Impact of glioma peritumoral edema, tumor size, and tumor location on alternating electric fields (AEF) therapy in realistic 3D rat glioma models: a computational study. Phys Med Biol 2024; 69:085015. [PMID: 38417178 DOI: 10.1088/1361-6560/ad2e6c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 02/28/2024] [Indexed: 03/01/2024]
Abstract
Objective.Alternating electric fields (AEF) therapy is a treatment modality for patients with glioblastoma. Tumor characteristics such as size, location, and extent of peritumoral edema may affect the AEF strength and distribution. We evaluated the sensitivity of the AEFs in a realistic 3D rat glioma model with respect to these properties.Approach.The electric properties of the peritumoral edema were varied based on calculated and literature-reported values. Models with different tumor composition, size, and location were created. The resulting AEFs were evaluated in 3D rat glioma models.Main results.In all cases, a pair of 5 mm diameter electrodes induced an average field strength >1 V cm-1. The simulation results showed that a negative relationship between edema conductivity and field strength was found. As the tumor core size was increased, the average field strength increased while the fraction of the shell achieving >1.5 V cm-1decreased. Increasing peritumoral edema thickness decreased the shell's mean field strength. Compared to rostrally/caudally, shifting the tumor location laterally/medially and ventrally (with respect to the electrodes) caused higher deviation in field strength.Significance.This study identifies tumor properties that are key drivers influencing AEF strength and distribution. The findings might be potential preclinical implications.
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Affiliation(s)
- Ha Nguyen
- Baylor University, Waco, TX, 76706, United States of America
| | | | - Christoph Pohling
- Loma Linda University, Loma Linda, CA, 92350, United States of America
| | - Edwin Chang
- Stanford University, Stanford, CA, 94305, United States of America
| | - Vicky Yamamoto
- University of Southern California-Keck School of Medicine, Los Angeles, CA, 90033, United States of America
| | - Yuping Zeng
- University of Delaware, Newark, DE, 19716, United States of America
| | - Ying Nie
- Loma Linda University, Loma Linda, CA, 92350, United States of America
| | - Samuel Van Buskirk
- University of Texas at San Antonio, San Antonio, TX, 78249, United States of America
| | | | - Chirag B Patel
- The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, United States of America
- The University of Texas MD Anderson UTHealth Graduate School of Biomedical Sciences at Houston, Houston, TX, 77030, United States of America
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15
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Barabás G. Parameter Sensitivity of Transient Community Dynamics. Am Nat 2024; 203:473-489. [PMID: 38489777 DOI: 10.1086/728764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/17/2024]
Abstract
AbstractTransient dynamics have always intrigued ecologists, but current rapid environmental change (inducing transients even in previously undisturbed systems) has highlighted their importance more than ever. Here, I introduce a method for analyzing the sensitivity of transient ecological dynamics to parameter perturbations. The question the method answers is: how would the community dynamics have unfolded for some time horizon had the parameters been slightly different? I apply the method to three empirically parameterized models: competition between native forbs and exotic grasses in California, a host-parasitoid system, and an experimental chemostat predator-prey model. These applications showcase the ecological insights one can gain from models using transient sensitivity analysis. First, one can find parameters and their combinations whose perturbations disproportionately affect a system. Second, one can identify particular windows of time during which the predicted deviation from the unperturbed trajectories is especially large and utilize this information for management purposes. Third, there is an inverse relationship between transient and long-term sensitivities whenever the interacting populations are ecologically similar; paradoxically, the smaller the immediate response of the system, the more extreme its long-term response will be.
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16
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Hernandez RJ, Madhusudhan S, Zheng Y, El-Bouri WK. Linking Vascular Structure and Function: Image-Based Virtual Populations of the Retina. Invest Ophthalmol Vis Sci 2024; 65:40. [PMID: 38683566 PMCID: PMC11059806 DOI: 10.1167/iovs.65.4.40] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 04/02/2024] [Indexed: 05/01/2024] Open
Abstract
Purpose This study explored the relationship among microvascular parameters as delineated by optical coherence tomography angiography (OCTA) and retinal perfusion. Here, we introduce a versatile framework to examine the interplay between the retinal vascular structure and function by generating virtual vasculatures from central retinal vessels to macular capillaries. Also, we have developed a hemodynamics model that evaluates the associations between vascular morphology and retinal perfusion. Methods The generation of the vasculature is based on the distribution of four clinical parameters pertaining to the dimension and blood pressure of the central retinal vessels, constructive constrained optimization, and Voronoi diagrams. Arterial and venous trees are generated in the temporal retina and connected through three layers of capillaries at different depths in the macula. The correlations between total retinal blood flow and macular flow fraction and vascular morphology are derived as Spearman rank coefficients, and uncertainty from input parameters is quantified. Results A virtual cohort of 200 healthy vasculatures was generated. Means and standard deviations for retinal blood flow and macular flow fraction were 20.80 ± 7.86 µL/min and 15.04% ± 5.42%, respectively. Retinal blood flow was correlated with vessel area density, vessel diameter index, fractal dimension, and vessel caliber index. The macular flow fraction was not correlated with any morphological metrics. Conclusions The proposed framework is able to reproduce vascular networks in the macula that are morphologically and functionally similar to real vasculature. The framework provides quantitative insights into how macular perfusion can be affected by changes in vascular morphology delineated on OCTA.
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Affiliation(s)
- Rémi J. Hernandez
- Liverpool Centre for Cardiovascular Science, University of Liverpool and Liverpool Heart and Chest Hospital, Liverpool, United Kingdom
- Department of Cardiovascular and Metabolic Medicine, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Savita Madhusudhan
- St Paul's Eye Unit, Liverpool University Hospitals NHS Foundation Trust, Liverpool, United Kingdom
- Department of Eye and Vision Sciences, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Yalin Zheng
- St Paul's Eye Unit, Liverpool University Hospitals NHS Foundation Trust, Liverpool, United Kingdom
- Department of Eye and Vision Sciences, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Wahbi K. El-Bouri
- Liverpool Centre for Cardiovascular Science, University of Liverpool and Liverpool Heart and Chest Hospital, Liverpool, United Kingdom
- Department of Cardiovascular and Metabolic Medicine, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
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17
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Lo SCY, McCullough JWS, Xue X, Coveney PV. Uncertainty quantification of the impact of peripheral arterial disease on abdominal aortic aneurysms in blood flow simulations. J R Soc Interface 2024; 21:20230656. [PMID: 38593843 PMCID: PMC11003782 DOI: 10.1098/rsif.2023.0656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 03/05/2024] [Indexed: 04/11/2024] Open
Abstract
Peripheral arterial disease (PAD) and abdominal aortic aneurysms (AAAs) often coexist and pose significant risks of mortality, yet their mutual interactions remain largely unexplored. Here, we introduce a fluid mechanics model designed to simulate the haemodynamic impact of PAD on AAA-associated risk factors. Our focus lies on quantifying the uncertainty inherent in controlling the flow rates within PAD-affected vessels and predicting AAA risk factors derived from wall shear stress. We perform a sensitivity analysis on nine critical model parameters through simulations of three-dimensional blood flow within a comprehensive arterial geometry. Our results show effective control of the flow rates using two-element Windkessel models, although specific outlets need attention. Quantities of interest like endothelial cell activation potential (ECAP) and relative residence time are instructive for identifying high-risk regions, with ECAP showing greater reliability and adaptability. Our analysis reveals that the uncertainty in the quantities of interest is 187% of that of the input parameters. Notably, parameters governing the amplitude and frequency of the inlet velocity exert the strongest influence on the risk factors' variability and warrant precise determination. This study forms the foundation for patient-specific simulations involving PAD and AAAs which should ultimately improve patient outcomes and reduce associated mortality rates.
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Affiliation(s)
- Sharp C. Y. Lo
- Centre for Computational Science, University College London, London, UK
| | | | - Xiao Xue
- Centre for Computational Science, University College London, London, UK
| | - Peter V. Coveney
- Centre for Computational Science, University College London, London, UK
- Advanced Research Computing Centre, University College London, London, UK
- Informatics Institute, Faculty of Science, University of Amsterdam, Amsterdam, The Netherlands
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18
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Khalili E, Daversin-Catty C, Olivares AL, Mill J, Camara O, Valen-Sendstad K. On the importance of fundamental computational fluid dynamics toward a robust and reliable model of left atrial flows. Int J Numer Method Biomed Eng 2024; 40:e3804. [PMID: 38286150 DOI: 10.1002/cnm.3804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 08/31/2023] [Accepted: 01/07/2024] [Indexed: 01/31/2024]
Abstract
Computational fluid dynamics (CFD) studies of left atrial flows have reached a sophisticated level, for example, revealing plausible relationships between hemodynamics and stresses with atrial fibrillation. However, little focus has been on fundamental fluid modeling of LA flows. The purpose of this study was to investigate the spatiotemporal convergence, along with the differences between high- (HR) versus normal-resolution/accuracy (NR) solution strategies, respectively. Rigid wall CFD simulations were conducted on 12 patient-specific left atrial geometries obtained from computed tomography scans, utilizing a second-order accurate and space/time-centered solver. The convergence studies showed an average variability of around 30% and 55% for time averaged wall shear stress (WSS), oscillatory shear index (OSI), relative residence time (RRT), and endothelial cell activation potential (ECAP), even between intermediate spatial and temporal resolutions, in the left atrium (LA) and left atrial appendage (LAA), respectively. The comparison between HR and NR simulations showed good correlation in the LA for WSS, RRT, and ECAP (R 2 > .9 ), but not for OSI (R 2 = .63 ). However, there were poor correlations in the LAA especially for OSI, RRT, and ECAP (R 2 = .55, .63, and .61, respectively), except for WSS (R 2 = .81 ). The errors are comparable to differences previously reported with disease correlations. To robustly predict atrial hemodynamics and stresses, numerical resolutions of 10 M elements (i.e., Δ x = ∼ .5 mm) and 10 k time-steps per cycle seem necessary (i.e., one order of magnitude higher than normally used in both space and time). In conclusion, attention to fundamental numerical aspects is essential toward establishing a plausible, robust, and reliable model of LA flows.
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Affiliation(s)
- Ehsan Khalili
- Department of Computational Physiology, Simula Research Laboratory, Oslo, Norway
| | - Cécile Daversin-Catty
- Department of Numerical Analysis and Scientific Computing, Simula Research Laboratory, Oslo, Norway
| | - Andy L Olivares
- Department of Information and Communication Technologies, Universitat Pompeu Fabra, Barcelona, Spain
| | - Jordi Mill
- Department of Information and Communication Technologies, Universitat Pompeu Fabra, Barcelona, Spain
| | - Oscar Camara
- Department of Information and Communication Technologies, Universitat Pompeu Fabra, Barcelona, Spain
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Zheng Z, Zhang Z, Huang C. Damage Monitoring of Steel Bars Based on Torsional Guided Waves. Sensors (Basel) 2024; 24:2047. [PMID: 38610259 PMCID: PMC11013979 DOI: 10.3390/s24072047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 03/11/2024] [Accepted: 03/15/2024] [Indexed: 04/14/2024]
Abstract
Ultrasonic guided waves represent a new development in the field of non-destructive testing. Longitudinal guided waves are mostly used to monitor the damage of steel bars, but the received signal is usually degraded and noisy owing to its dispersive propagation and multimodal behavior, making its implementation and location challenging. The torsional mode of T (0, 1) is not dispersive in the propagation of a steel bar and only produces circumferential displacement. It was chosen, in this study, to conduct guided wave-based damage monitoring on steel bars to reduce the signal processing complexity. The defects of steel bars, including circular surface defects, internal defects, and uniform damage defects, were thoroughly investigated, respectively, using numerical simulation. The waves were excited and received using the pitch-and-catch technique and the collected monitoring signals were processed using Hilbert transformation to highlight the amplitude and time-of-flight values of the wave signals, which were used for defect identification. In this paper, the reflectivity of guided waves is compared between torsional waves and longitudinal waves, in each case. The impact of defect size changes on damage monitoring is studied and the sensitivity of both the wave frequency and the wave mode (L and T) is also discussed. The results show that the monitoring method based on the torsional wave T (0, 1) is more sensitive to surface defects than the conventional method based on longitudinal waves. The reflectivity of the torsional wave T (0, 1) can be twice that of the longitudinal wave L (0, 1) when the depth of the defect in the circumferential grooves is less than 50% of the diameter of the steel bar. It is more sensitive to shallow surface defects within half of the bar's radius, and it can also effectively identify defects under the conditions of the uniform damage defects of steel bars, even when the measurements are heavily noise-polluted. This proves the superiority of the torsional guided wave T (0, 1) in defect monitoring and provides a theoretical basis for the application of the torsional guided wave T (0, 1) in actual monitoring.
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Affiliation(s)
- Zhupeng Zheng
- Department of Civil Engineering, Xiamen University, Xiamen 361005, China;
- Shenzhen Research Institute, Xiamen University, Shenzhen 518087, China
| | - Zihao Zhang
- Department of Civil Engineering, Xiamen University, Xiamen 361005, China;
| | - Cheng Huang
- Xiamen R&B Baicheng Construction Investment Co., Ltd., Xiamen 361009, China;
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Voigt JD, Potter BK, Souza J, Forsberg J, Melton D, Hsu JR, Wilke B. Lifetime cost-effectiveness analysis osseointegrated transfemoral versus socket prosthesis using Markov modelling. Bone Jt Open 2024; 5:218-226. [PMID: 38484760 PMCID: PMC10949340 DOI: 10.1302/2633-1462.53.bjo-2023-0089.r1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/21/2024] Open
Abstract
Aims Prior cost-effectiveness analyses on osseointegrated prosthesis for transfemoral unilateral amputees have analyzed outcomes in non-USA countries using generic quality of life instruments, which may not be appropriate when evaluating disease-specific quality of life. These prior analyses have also focused only on patients who had failed a socket-based prosthesis. The aim of the current study is to use a disease-specific quality of life instrument, which can more accurately reflect a patient's quality of life with this condition in order to evaluate cost-effectiveness, examining both treatment-naïve and socket refractory patients. Methods Lifetime Markov models were developed evaluating active healthy middle-aged male amputees. Costs of the prostheses, associated complications, use/non-use, and annual costs of arthroplasty parts and service for both a socket and osseointegrated (OPRA) prosthesis were included. Effectiveness was evaluated using the questionnaire for persons with a transfemoral amputation (Q-TFA) until death. All costs and Q-TFA were discounted at 3% annually. Sensitivity analyses on those cost variables which affected a change in treatment (OPRA to socket, or socket to OPRA) were evaluated to determine threshold values. Incremental cost-effectiveness ratios (ICERs) were calculated. Results For treatment-naïve patients, the lifetime ICER for OPRA was $279/quality-adjusted life-year (QALY). For treatment-refractory patients the ICER was $273/QALY. In sensitivity analysis, the variable thresholds that would affect a change in the course of treatment based on cost (from socket to OPRA), included the following for the treatment-naïve group: yearly replacement components for socket > $8,511; cost yearly replacement parts OPRA < $1,758; and for treatment-refractory group: yearly replacement component for socket of > $12,467. Conclusion The use of the OPRA prosthesis in physically active transfemoral amputees should be considered as a cost-effective alternative in both treatment-naïve and treatment-refractory socket prosthesis patients. Disease-specific quality of life assessments such as Q-TFA are more sensitive when evaluating cost-effectiveness.
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Affiliation(s)
- Jeffrey D. Voigt
- Walter Reed National Military Medical Center, Bethesda, Maryland, USA
| | - Benjamin K. Potter
- Walter Reed National Military Medical Center, Bethesda, Maryland, USA
- Uniformed Services University of the Health Sciences, Bethseda, Maryland, USA
| | - Jason Souza
- Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Jonathan Forsberg
- Johns Hopkins University, Baltimore, Maryland, USA
- Sibley Memorial Hospital, Washington DC, USA
| | - Danielle Melton
- University Colorado School of Medicine, Aurora, Colorado, USA
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21
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Vorwerk J, Wolters CH, Baumgarten D. Global sensitivity of EEG source analysis to tissue conductivity uncertainties. Front Hum Neurosci 2024; 18:1335212. [PMID: 38532791 PMCID: PMC10963400 DOI: 10.3389/fnhum.2024.1335212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 01/22/2024] [Indexed: 03/28/2024] Open
Abstract
Introduction To reliably solve the EEG inverse problem, accurate EEG forward solutions based on a detailed, individual volume conductor model of the head are essential. A crucial-but often neglected-aspect in generating a volume conductor model is the choice of the tissue conductivities, as these may vary from subject to subject. In this study, we investigate the sensitivity of EEG forward and inverse solutions to tissue conductivity uncertainties for sources distributed over the whole cortex surface. Methods We employ a detailed five-compartment head model distinguishing skin, skull, cerebrospinal fluid, gray matter, and white matter, where we consider uncertainties of skin, skull, gray matter, and white matter conductivities. We use the finite element method (FEM) to calculate EEG forward solutions and goal function scans (GFS) as inverse approach. To be able to generate the large number of EEG forward solutions, we employ generalized polynomial chaos (gPC) expansions. Results For sources up to a depth of 4 cm, we find the strongest influence on the signal topography of EEG forward solutions for the skull conductivity and a notable effect for the skin conductivity. For even deeper sources, e.g., located deep in the longitudinal fissure, we find an increasing influence of the white matter conductivity. The conductivity variations translate to varying source localizations particularly for quasi-tangential sources on sulcal walls, whereas source localizations of quasi-radial sources on the top of gyri are less affected. We find a strong correlation between skull conductivity and the variation of source localizations and especially the depth of the reconstructed source for quasi-tangential sources. We furthermore find a clear but weaker correlation between depth of the reconstructed source and the skin conductivity. Discussion Our results clearly show the influence of tissue conductivity uncertainties on EEG source analysis. We find a particularly strong influence of skull and skin conductivity uncertainties.
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Affiliation(s)
- Johannes Vorwerk
- Institute of Electrical and Biomedical Engineering, UMIT TIROL—Private University for Health Sciences and Health Technology, Hall in Tirol, Austria
| | - Carsten H. Wolters
- Institute for Biomagnetism and Biosignalanalysis, University of Münster, Münster, Germany
- Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, Münster, Germany
| | - Daniel Baumgarten
- Institute of Electrical and Biomedical Engineering, UMIT TIROL—Private University for Health Sciences and Health Technology, Hall in Tirol, Austria
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Jimoh KA, Hashim N, Shamsudin R, Che Man H, Jahari M. Optimization of computational intelligence approach for the prediction of glutinous rice dehydration. J Sci Food Agric 2024. [PMID: 38451113 DOI: 10.1002/jsfa.13445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 02/09/2024] [Accepted: 03/05/2024] [Indexed: 03/08/2024]
Abstract
BACKGROUND Five computational intelligence approaches, namely Gaussian process regression (GPR), artificial neural network (ANN), decision tree (DT), ensemble of trees (EoT) and support vector machine (SVM), were used to describe the evolution of moisture during the dehydration process of glutinous rice. The hyperparameters of the models were optimized with three strategies: Bayesian optimization, grid search and random search. To understand the parameters that facilitate intelligence model adaptation to the dehydration process, global sensitivity analysis (GSA) was used to compute the impact of the input variables on the model output. RESULT The result shows that the optimum computational intelligence techniques include the 3-9-1 topology trained with Bayesian regulation function for ANN, Gaussian kernel function for SVM, Matérn covariance function combined with zero mean function for GPR, boosting method for EoT and 4 minimum leaf size for DT. GPR has the highest performance with R2 of 100% and 99.71% during calibration and testing of the model, respectively. GSA reveals that all the models significantly rely on the variation in time as the main factor that affects the model outputs. CONCLUSION Therefore, the computational intelligence models, especially GPR, can be applied for an effective description of moisture evolution during small-scale and industrial dehydration of glutinous rice. © 2024 Society of Chemical Industry.
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Affiliation(s)
- Kabiru Ayobami Jimoh
- Department of Biological and Agricultural Engineering, Faculty of Engineering, Universiti Putra Malaysia, Serdang, Malaysia
| | - Norhashila Hashim
- Department of Biological and Agricultural Engineering, Faculty of Engineering, Universiti Putra Malaysia, Serdang, Malaysia
- SMART Farming Technology Research Centre, Faculty of Engineering, Universiti Putra Malaysia, Serdang, Malaysia
| | - Rosnah Shamsudin
- Department of Process and Food Engineering, Faculty of Engineering, Universiti Putra Malaysia, Serdang, Malaysia
| | - Hasfalina Che Man
- Department of Biological and Agricultural Engineering, Faculty of Engineering, Universiti Putra Malaysia, Serdang, Malaysia
- SMART Farming Technology Research Centre, Faculty of Engineering, Universiti Putra Malaysia, Serdang, Malaysia
| | - Mahirah Jahari
- Department of Biological and Agricultural Engineering, Faculty of Engineering, Universiti Putra Malaysia, Serdang, Malaysia
- SMART Farming Technology Research Centre, Faculty of Engineering, Universiti Putra Malaysia, Serdang, Malaysia
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Jeon S, Lemosquet S, Toulemonde AC, Kiessé TS, Nozière P. Sensitivity analysis of the INRA 2018 feeding system for ruminants by a one-at-a-time approach: Effects of dietary input variables on predictions of multiple responses of dairy cattle. J Dairy Sci 2024:S0022-0302(24)00533-2. [PMID: 38460873 DOI: 10.3168/jds.2023-24361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 01/31/2024] [Indexed: 03/11/2024]
Abstract
In the INRA 2018 feeding system for ruminants, the prediction of multiple animal responses is based on the integration of the characteristics of the animal and the available feedstuff characteristics, as well as the rationing objectives. In this framework, the characterization of feedstuffs in terms of net energy, digestible protein, and fill units requirs information on their chemical composition, digestibility, and degradability. Despite the importance of these feed characteristics, a comprehensive assessment of their impact on the responses predicted by the INRA 2018 feeding system has not been carried out. Thus, our study investigated how variables predicted by the INRA feeding system (i.e., outputs) for dairy cows are affected by variation in feed characterization (i.e., inputs). Five input variables were selected for the sensitivity analysis (SA): CP, OM apparent digestibility (OMd), GE, effective degradability of nitrogen assuming a passage rate of 6%/h (ED6_N) and true intestinal digestibility (dr_N) of nitrogen. A one-at-a-time SA was performed on predicted digestive, productive and environmental output variables for dairy cows with 6 contrasted diets. These 6 diets were formulated to meet 95% of the potential daily milk production (37.5 kg) of a multiparous cow at wk 14 of lactation. Then, the values of the 5 key input variables of each feedstuff were randomly sampled around the INRA 2018 feed table values (reference point). The response of the output variable to the variation of the input variable was quantified and compared using the tangent value at the reference point and the normalized sensitivity coefficient. Among the major final output variables, CP and dr_N had the greatest impact on nitrogen (N) excretion in urine (as a proportion of total fecal and urinary N excretion, UN/TN), OMd and GE had the greatest impact on N utilization efficiency (N in milk as proportion of intake N, NUE), and ED6_N had the greatest impact on milk protein yield (MPY). Additionally, CP, GE, and dr_N had the least effect on methane emission, OMd had the least effect on UN/TN, and ED6_N had the least effect on NUE. The responses of most output variables to ED6_N and dr_N variations were highly dependent on diet, and were related to the ratio between PDI (i.e., metabolizable protein) and UFL (i.e., NEL) at the reference point of each diet. In conclusion, we were able to analyze the response of output variables to the variations of the input variables, using the tangent and its normalized value at the reference point. The predicted final outputs were more impacted by variations in CP, GE, and OMd. The other 2 input variables, ED6_N and dr_N, had a smaller effect on the final output variables, but the responses varied between the diets according to their PDI/UFL ratio. Among the final output variables affected by ED6_N, MPY was the most impacted, but when quantified this impact was at an acceptable level. Our present study was conducted using 6 representative diets for dairy cattle fed at their potential, but should be completed by the analysis of more diverse conditions.
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Affiliation(s)
- Seoyoung Jeon
- UMR Herbivores, INRAE, VetAgro Sup, 63122 Saint-Genès-Champanelle, France
| | | | | | | | - Pierre Nozière
- UMR Herbivores, INRAE, VetAgro Sup, 63122 Saint-Genès-Champanelle, France.
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Xiaowu W, Qiang Z, Yike H, Wu Z, Yiheng J, Xuemei C, Sen L, Jiong C. Causal relationship between atrial fibrillation/warfarin and cutaneous melanoma: a two-sample Mendelian randomization study. Front Med (Lausanne) 2024; 11:1336849. [PMID: 38504913 PMCID: PMC10948620 DOI: 10.3389/fmed.2024.1336849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2023] [Accepted: 02/26/2024] [Indexed: 03/21/2024] Open
Abstract
Purpose In recent years, the relationship between malignant tumors and atrial fibrillation has attracted more and more attention. Atrial fibrillation can also cause a series of adverse events, such as the risk of thromboembolism. Also, Warfarin is often used here. But, the relationship between cutaneous melanoma and atrial fibrillation, and between cutaneous melanoma and warfarin is still unclear. Therefore, we used a two-sample Mendelian randomization to assess the causal relationship between atrial fibrillation/warfarin and cutaneous melanoma (cM). Methods Firstly, atrial fibrillation (ukb-b-11550; nCase = 3,518, nControl = 459,415) and warfarin (ukb-b-13248; nCase = 4,623, nControl = 458,310) as exposures, with genome-wide association studies (GWAS) data from the United Kingdom Biobank. And cM (ieu-b-4969; nCase = 3,751, nControl = 372,016) as outcome, with GWAS data from the IEU Open GWAS project. Subsequently, single-nucleotide polymorphisms (SNPs) were filtered from GWAS studies using quality control measures. In addition, two-sample Mendelian randomization (MR) analysis was performed to explore the causal relationship between atrial fibrillation or warfarin and cM and used inverse variance weighting (IVW) as the primary analytical method. Finally, relevant heterogeneity and sensitivity analysis were performed to ensure the accuracy of the results. Results A causal relationship between atrial fibrillation and cutaneous melanoma was observed, and between warfarin and cutaneous melanoma. Conclusion The atrial fibrillation may play a causal role in the development of cutaneous melanoma, but the mechanism and the causal relationship between warfarin and cutaneous melanoma needs to be further elucidated.
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Affiliation(s)
- Wang Xiaowu
- Department of Burns and Skin Repair Surgery, The Third Affiliated Hospital of Wenzhou Medical University (Ruian People's Hospital), Wenzhou, China
| | - Zhou Qiang
- Department of Otolaryngology, The Third Affiliated Hospital of Wenzhou Medical University (Ruian People's Hospital), Wenzhou, China
| | - Han Yike
- Department of Gynaecology and Obstetrics, The Third Affiliated Hospital of Wenzhou Medical University (Ruian People's Hospital), Wenzhou, China
| | - Zhixuan Wu
- Department of Nail and Breast Surgery, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Jin Yiheng
- College of Public Health and Management, Wenzhou Medical University, Wenzhou, China
| | - Chen Xuemei
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, China
| | - Lin Sen
- Department of Otolaryngology, The Third Affiliated Hospital of Wenzhou Medical University (Ruian People's Hospital), Wenzhou, China
| | - Chen Jiong
- Department of Burns and Skin Repair Surgery, The Third Affiliated Hospital of Wenzhou Medical University (Ruian People's Hospital), Wenzhou, China
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25
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He J, Zhan L, Yang Y, Xu Y. Global Sensitivity Analysis of Factors Influencing the Surface Temperature of Mold during Autoclave Processing. Polymers (Basel) 2024; 16:705. [PMID: 38475388 DOI: 10.3390/polym16050705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Revised: 02/29/2024] [Accepted: 03/02/2024] [Indexed: 03/14/2024] Open
Abstract
During the process of forming carbon fiber reinforced plastics (CFRP) in an autoclave, deeply understanding the global sensitivity of factors influencing mold surface temperature is of paramount importance for optimizing large frame-type mold thermally and enhancing curing quality. In this study, the convective heat transfer coefficient (CHTC), the thickness of composite laminates (TCL), the thickness of mold facesheet (TMF), the mold material type (MMT), and the thickness of the auxiliary materials layer (TAL) have been quantitatively assessed for the effects on the mold surface temperature. This assessment was conducted by building the thermal-chemical curing model of composite laminates and utilizing the Sobol global sensitivity analysis (GSA) method. Additionally, the interactions among these factors were investigated to gain a comprehensive understanding of their combined effects. The results show that the sensitivity order of these factors is as follows: CHTC > MMT > TMF > TCL > TAL. Moreover, CHTC, MMT, and TMF are the main factors influencing mold surface temperature, as the sum of their first-order sensitivity indices accounts for over 97.3%. The influence of a single factor is more significant than that of the interaction between factors since the sum of the first-order sensitivity indices of the factors is more than 78.1%. This study will support the development of science-based guidelines for the thermal design of molds and associated heating equipment design.
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Affiliation(s)
- Jiayang He
- Light Alloys Research Institute, Central South University, Changsha 410083, China
- Department of Energy and Electrical Engineering, Hunan University of Humanities, Science and Technology, Loudi 417000, China
| | - Lihua Zhan
- Light Alloys Research Institute, Central South University, Changsha 410083, China
- College of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China
| | - Youliang Yang
- Light Alloys Research Institute, Central South University, Changsha 410083, China
| | - Yongqian Xu
- College of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China
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26
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Nian F, Li F. Epidemic propagation risk study with effective fractal dimension. Risk Anal 2024; 44:612-622. [PMID: 37435956 DOI: 10.1111/risa.14192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 06/11/2023] [Accepted: 06/15/2023] [Indexed: 07/13/2023]
Abstract
In this article, the risk of epidemic transmission on complex networks is studied from the perspective of effective fractal dimension. First, we introduce the method of calculating the effective fractal dimensionD B ${D}_B$ of the network by taking a scale-free network as an example. Second, we propose the construction method of administrative fractal network and calculate theD B ${D}_B$ . using the classical susceptible exposed infectious removed (SEIR) infectious disease model, we simulate the virus propagation process on the administrative fractal network. The results show that the larger theD B ${D}_B$ is, the higher the risk of virus transmission is. Later, we proposed five parameters P, M, B, F, and D, where P denotes population mobility, M denotes geographical distance, B denotes GDP, F denotesD B ${D}_B$ , and D denotes population density. The new epidemic growth index formulaI = ( P + ( 1 - M ) + B ) ( F + D ) $I = {( {P + ( {1 - M} ) + B} )}^{( {F + D} )}$ was obtained by combining these five parameters, and the validity of I in epidemic transmission risk assessment was demonstrated by parameter sensitivity analysis and reliability analysis. Finally, we also confirmed the reliability of the SEIR dynamic transmission model in simulating early COVID-19 transmission trends and the ability of timely quarantine measures to effectively control the spread of the epidemic.
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Affiliation(s)
- Fuzhong Nian
- School of Computer and Communication, Lanzhou University of Technology, Lanzhou, P.R. China
| | - Fangfang Li
- School of Computer and Communication, Lanzhou University of Technology, Lanzhou, P.R. China
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27
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Mrad D, Boukhari S, Dairi S, Djebbar Y. Modeling the sediment yield and estimating the best management practices in the Seybouse basin, Northeastern Algeria. Water Sci Technol 2024; 89:1497-1511. [PMID: 38557714 DOI: 10.2166/wst.2024.067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Accepted: 02/16/2024] [Indexed: 04/04/2024]
Abstract
Identifying vulnerable areas to erosion within the watershed and implementing best management practices (BMPs) are crucial steps in mitigating watershed degradation by minimizing sediment yields. The present study evaluates and identifies the BMPs in the Seybouse basin, northeastern Algeria, using the Soil and Water Assessment Tool (SWAT) model. After successful calibration and validation, the model demonstrated a satisfactory ability to simulate monthly discharge and sediment. Then, the calibrated model was employed to evaluate the efficacy of diverse management practices in sediment control. In the SWAT, three soil and conservation practices, as well as vegetated filter strips (VFSs), grade stabilization structures (GSSs), and terracing were evaluated. The average annual sediment yield in the Seybouse watershed is determined to be 14.43 t/ha year, constituting 71% of the total soil loss. VFS demonstrated a sediment reduction of 37.30%, GSS 20.40%, and terracing 42.30%. Among these strategies, terracing results in the greatest reduction, followed by VFS. The results of this study area can be useful for informed decision-making regarding optimal watershed management strategies.
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Affiliation(s)
- Dounia Mrad
- Laboratory of Research Infra-Res, University Mohamed Cherif MESAADIA, Souk-Ahras, Algeria E-mail:
| | - Sofiane Boukhari
- Laboratory of Research Infra-Res, University Mohamed Cherif MESAADIA, Souk-Ahras, Algeria
| | - Sabri Dairi
- Laboratory of Research Infra-Res, University Mohamed Cherif MESAADIA, Souk-Ahras, Algeria
| | - Yassine Djebbar
- Laboratory of Research Infra-Res, University Mohamed Cherif MESAADIA, Souk-Ahras, Algeria
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Haider MA, Pearce KJ, Chesler NC, Hill NA, Olufsen MS. Application and reduction of a nonlinear hyperelastic wall model capturing ex vivo relationships between fluid pressure, area, and wall thickness in normal and hypertensive murine left pulmonary arteries. Int J Numer Method Biomed Eng 2024; 40:e3798. [PMID: 38214099 DOI: 10.1002/cnm.3798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 08/10/2023] [Accepted: 11/26/2023] [Indexed: 01/13/2024]
Abstract
Pulmonary hypertension is a cardiovascular disorder manifested by elevated mean arterial blood pressure (>20 mmHg) together with vessel wall stiffening and thickening due to alterations in collagen, elastin, and smooth muscle cells. Hypoxia-induced (type 3) pulmonary hypertension can be studied in animals exposed to a low oxygen environment for prolonged time periods leading to biomechanical alterations in vessel wall structure. This study introduces a novel approach to formulating a reduced order nonlinear elastic structural wall model for a large pulmonary artery. The model relating blood pressure and area is calibrated using ex vivo measurements of vessel diameter and wall thickness changes, under controlled pressure conditions, in left pulmonary arteries isolated from control and hypertensive mice. A two-layer, hyperelastic, and anisotropic model incorporating residual stresses is formulated using the Holzapfel-Gasser-Ogden model. Complex relations predicting vessel area and wall thickness with increasing blood pressure are derived and calibrated using the data. Sensitivity analysis, parameter estimation, subset selection, and physical plausibility arguments are used to systematically reduce the 16-parameter model to one in which a much smaller subset of identifiable parameters is estimated via solution of an inverse problem. Our final reduced one layer model includes a single set of three elastic moduli. Estimated ranges of these parameters demonstrate that nonlinear stiffening is dominated by elastin in the control animals and by collagen in the hypertensive animals. The pressure-area relation developed in this novel manner has potential impact on one-dimensional fluids network models of vessel wall remodeling in the presence of cardiovascular disease.
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Affiliation(s)
- Mansoor A Haider
- Department of Mathematics, North Carolina State University, Raleigh, North Carolina, USA
| | - Katherine J Pearce
- Department of Mathematics, North Carolina State University, Raleigh, North Carolina, USA
| | - Naomi C Chesler
- Edwards Lifesciences Foundation Cardiovascular Innovation and Research Center & Department of Biomedical Engineering, University of California, Irvine (UCI), Irvine, California, USA
| | - Nicholas A Hill
- School of Mathematics and Statistics, University of Glasgow, Glasgow, UK
| | - Mette S Olufsen
- Department of Mathematics, North Carolina State University, Raleigh, North Carolina, USA
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29
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Hilhorst PLJ, Quicken S, van de Vosse FN, Huberts W. Efficient sensitivity analysis for biomechanical models with correlated inputs. Int J Numer Method Biomed Eng 2024; 40:e3797. [PMID: 38116742 DOI: 10.1002/cnm.3797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 09/08/2023] [Accepted: 11/26/2023] [Indexed: 12/21/2023]
Abstract
In most variance-based sensitivity analysis (SA) approaches applied to biomechanical models, statistical independence of the model input is assumed. However, often the model inputs are correlated. This might alter the interpretation of the SA results, which may severely impact the guidance provided during model development and personalization. Potential reasons for the infrequent usage of SA techniques that account for input correlation are the associated high computational costs, especially for models with many parameters, and the fact that the input correlation structure is often unknown. The aim of this study was to propose an efficient correlated global sensitivity analysis method by applying a surrogate model-based approach. Furthermore, this article demonstrates how correlated SA should be interpreted and how the applied method can guide the modeler during model development and personalization, even when the correlation structure is not entirely known beforehand. The proposed methodology was applied to a typical example of a pulse wave propagation model and resulted in accurate SA results that could be obtained at a theoretically 27,000× lower computational cost compared to the correlated SA approach without employing a surrogate model. Furthermore, our results demonstrate that input correlations can significantly affect SA results, which emphasizes the need to thoroughly investigate the effect of input correlations during model development. We conclude that our proposed surrogate-based SA approach allows modelers to efficiently perform correlated SA to complex biomechanical models and allows modelers to focus on input prioritization, input fixing and model reduction, or assessing the dependency structure between parameters.
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Affiliation(s)
- Pjotr L J Hilhorst
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Sjeng Quicken
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Frans N van de Vosse
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Wouter Huberts
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
- CARIM School for Cardiovascular Diseases, Biomedical Engineering, Maastricht University, Maastricht, The Netherlands
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30
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Aleshin-Guendel S, Sadinle M, Wakefield J. The central role of the identifying assumption in population size estimation. Biometrics 2024; 80:ujad028. [PMID: 38456546 DOI: 10.1093/biomtc/ujad028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 05/12/2022] [Accepted: 12/12/2023] [Indexed: 03/09/2024]
Abstract
The problem of estimating the size of a population based on a subset of individuals observed across multiple data sources is often referred to as capture-recapture or multiple-systems estimation. This is fundamentally a missing data problem, where the number of unobserved individuals represents the missing data. As with any missing data problem, multiple-systems estimation requires users to make an untestable identifying assumption in order to estimate the population size from the observed data. If an appropriate identifying assumption cannot be found for a data set, no estimate of the population size should be produced based on that data set, as models with different identifying assumptions can produce arbitrarily different population size estimates-even with identical observed data fits. Approaches to multiple-systems estimation often do not explicitly specify identifying assumptions. This makes it difficult to decouple the specification of the model for the observed data from the identifying assumption and to provide justification for the identifying assumption. We present a re-framing of the multiple-systems estimation problem that leads to an approach that decouples the specification of the observed-data model from the identifying assumption, and discuss how common models fit into this framing. This approach takes advantage of existing software and facilitates various sensitivity analyses. We demonstrate our approach in a case study estimating the number of civilian casualties in the Kosovo war.
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Affiliation(s)
- Serge Aleshin-Guendel
- Department of Biostatistics, University of Washington, Seattle, WA 98195, United States
| | - Mauricio Sadinle
- Department of Biostatistics, University of Washington, Seattle, WA 98195, United States
| | - Jon Wakefield
- Department of Biostatistics, University of Washington, Seattle, WA 98195, United States
- Department of Statistics, University of Washington, Seattle, WA 98195, United States
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31
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Liu S, Yang S, Zhang Y, Liu G(F. Multiply robust estimators in longitudinal studies with missing data under control-based imputation. Biometrics 2024; 80:ujad036. [PMID: 38393335 PMCID: PMC10885818 DOI: 10.1093/biomtc/ujad036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 12/05/2023] [Accepted: 12/19/2023] [Indexed: 02/25/2024]
Abstract
Longitudinal studies are often subject to missing data. The recent guidance from regulatory agencies, such as the ICH E9(R1) addendum addresses the importance of defining a treatment effect estimand with the consideration of intercurrent events. Jump-to-reference (J2R) is one classical control-based scenario for the treatment effect evaluation, where the participants in the treatment group after intercurrent events are assumed to have the same disease progress as those with identical covariates in the control group. We establish new estimators to assess the average treatment effect based on a proposed potential outcomes framework under J2R. Various identification formulas are constructed, motivating estimators that rely on different parts of the observed data distribution. Moreover, we obtain a novel estimator inspired by the efficient influence function, with multiple robustness in the sense that it achieves n1/2-consistency if any pairs of multiple nuisance functions are correctly specified, or if the nuisance functions converge at a rate not slower than n-1/4 when using flexible modeling approaches. The finite-sample performance of the proposed estimators is validated in simulation studies and an antidepressant clinical trial.
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Affiliation(s)
- Siyi Liu
- Department of Statistics, North Carolina State University, Raleigh, NC 27607, United States
| | - Shu Yang
- Department of Statistics, North Carolina State University, Raleigh, NC 27607, United States
| | - Yilong Zhang
- Merck & Co., Inc., Kenilworth, NJ 07033, United States
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32
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Liu CC, Yu RX, Aitkin M. The flaw of averages: Bayes factors as posterior means of the likelihood ratio. Pharm Stat 2024. [PMID: 38282048 DOI: 10.1002/pst.2355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 09/25/2023] [Accepted: 11/24/2023] [Indexed: 01/30/2024]
Abstract
As an alternative to the Frequentist p-value, the Bayes factor (or ratio of marginal likelihoods) has been regarded as one of the primary tools for Bayesian hypothesis testing. In recent years, several researchers have begun to re-analyze results from prominent medical journals, as well as from trials for FDA-approved drugs, to show that Bayes factors often give divergent conclusions from those of p-values. In this paper, we investigate the claim that Bayes factors are straightforward to interpret as directly quantifying the relative strength of evidence. In particular, we show that for nested hypotheses with consistent priors, the Bayes factor for the null over the alternative hypothesis is the posterior mean of the likelihood ratio. By re-analyzing 39 results previously published in the New England Journal of Medicine, we demonstrate how the posterior distribution of the likelihood ratio can be computed and visualized, providing useful information beyond the posterior mean alone.
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Affiliation(s)
- Charles C Liu
- Department of Biostatistics, Gilead Sciences, Foster City, CA, USA
| | - Ron Xiaolong Yu
- Department of Biostatistics, Gilead Sciences, Foster City, CA, USA
| | - Murray Aitkin
- School of Mathematics and Statistics, The University of Melbourne, Parkville, Victoria, Australia
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Li X, Ning Z, Lü M. Microchannel Gas Flow in the Multi-Flow Regime Based on the Lattice Boltzmann Method. Entropy (Basel) 2024; 26:84. [PMID: 38248209 PMCID: PMC10814513 DOI: 10.3390/e26010084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 12/21/2023] [Accepted: 01/09/2024] [Indexed: 01/23/2024]
Abstract
In this work, a lattice Boltzmann method (LBM) for studying microchannel gas flow is developed in the multi-flow regime. In the LBM, by comparing previous studies' results on effective viscosity in multi-flow regimes, the values of the rarefaction factor applicable to multi-flow regions were determined, and the relationship between relaxation time and Kn number with the rarefaction factor is given. The Kn number is introduced into the second-order slip boundary condition together with the combined bounce-back/specular-reflection (CBBSR) scheme to capture the gas flow in the multi-flow regime. Sensitivity analysis of the dimensionless flow rate to adjustable parameters using the Taguchi method was carried out, and the values of adjustable parameters were determined based on the results of the sensitivity analysis. The results show that the dimensionless flow rate is more sensitive to j than h. Numerical simulations of Poiseuille flow and pulsating flow in a microchannel with second-order slip boundary conditions are carried out to validate the method. The results show that the velocity profile and dimensionless flow rate simulated by the present numerical simulation method in this work are found in the multi-flow regime, and the phenomenon of annular velocity profile in the microchannel is reflected in the phases.
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Affiliation(s)
| | | | - Ming Lü
- School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044, China; (X.L.); (Z.N.)
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Wang L, Han Y, Cao C, Hu H, Li H. The non-linear link between non-high-density lipoprotein to high-density lipoprotein ratio and the risk of stroke in middle-aged and older adults in Chinese: a prospective cohort study from the China health and retirement longitudinal study. Front Endocrinol (Lausanne) 2024; 14:1303336. [PMID: 38288470 PMCID: PMC10823364 DOI: 10.3389/fendo.2023.1303336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 12/20/2023] [Indexed: 02/01/2024] Open
Abstract
Objective This study aims to assess the association between the non-HDL-c/HDL-c ratio and stroke risk among middle-aged and older adults participating in the China Health and Retirement Longitudinal Study (CHARLS). Methods This study conducted a prospective cohort analysis, enrolling a total of 10,183 participants who met the designated criteria from CHARLS between 2011 and 2012. We then used the Cox proportional-hazards regression model to explore the relationship between baseline non-HDL-c/HDL-c ratio and stroke risk. Using a Cox proportional hazards regression with cubic spline function, we were able to identify the non-linear relationship between the non-HDL-c/HDL-c ratio and stroke occurrence. A series of sensitivity analyses were also carried out. Results The average age of the participants included in this study was 59.16 ± 9.35 years, and 4,735 individuals (46.68%) were male. Over a median follow-up period of 7.0 years, a total of 1,191 people (11.70%) experienced a stroke. Using a Cox proportional hazards regression model that was fully adjusted, we found no statistically significant correlation between the non-HDL-c/HDL-c ratio and the risk of stroke (HR=1.022; 95% CI 0.964, 1.083). Nevertheless, we did observe a non-linear relationship and saturation effect between the non-HDL-c/HDL-c ratio and stroke. Employing a two-piece Cox proportional hazards regression model and a recursive algorithm, we determined an inflection point of 2.685 for the non-HDL-c/HDL-c ratio. In instances where the non-HDL-c/HDL-c ratio fell below 2.685, for every 1-unit decrease in the non-HDL-c/HDL-c ratio, the likelihood of stroke decreased by 21.4% (HR=1.214, 95% CI: 1.039-1.418). In contrast, when the non-HDL-c/HDL-c ratio exceeded 2.685, there was no statistically significant change in the risk of stroke for each unit decrease in the non-HDL-c/HDL-c ratio (HR: 0.967, 95% CI: 0.897-1.042). The consistency of these findings across multiple sensitivity analyses suggests their robustness. Conclusion This study unveils a non-linear relationship between the non-HDL-c/HDL-c ratio and stroke risk in middle-aged and older adults in China. Specifically, when the non-HDL-c/HDL-c ratio was below 2.685, a significant and clearly positive association with stroke risk was observed. Additionally, maintaining the non-HDL-c/HDL-c ratio below 2.685 could potentially lead to a substantial reduction in the risk of stroke.
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Affiliation(s)
- Lanbo Wang
- Department of Radiology, Shengjing Hospital of China Medical University, Shenyang, Liaoning, China
| | - Yong Han
- Department of Emergency, Shenzhen Second People’s Hospital, Shenzhen, Guangdong, China
- Department of Emergency, The First Affiliated Hospital of Shenzhen University, Shenzhen, Guangdong, China
| | - Changchun Cao
- Department of Rehabilitation, Shenzhen Dapeng New District Nan’ao People’s Hospital, Shenzhen, Guangdong, China
| | - Haofei Hu
- Department of Nephrology, Shenzhen Second People’s Hospital, Shenzhen, Guangdong, China
- Department of Nephrology, The First Affiliated Hospital of Shenzhen University, Shenzhen, Guangdong, China
| | - Han Li
- Department of Neurosurgery, Shengjing Hospital of China Medical University, Shenyang, Liaoning, China
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Zambrano-Navea C, Bastida F, Aguilera MJ, Gonzalez-Andujar JL. Economical Evaluation of Reduced Herbicide Doses Application Rates to Control Phalaris brachystachys (Short-Spiked Canary Grass) in a Biennial Wheat-Sunflower Rotation in Mediterranean Dryland: A Modelling Approach. Plants (Basel) 2024; 13:212. [PMID: 38256765 PMCID: PMC10821078 DOI: 10.3390/plants13020212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 12/29/2023] [Accepted: 12/30/2023] [Indexed: 01/24/2024]
Abstract
Phalaris brachystachys (short-spiked canary grass) is considered to be among the most troublesome cereal weeds in Mediterranean areas. A bioeconomic model, based on population dynamics, competition and economic sub-models, was developed to simulate the long-term economic consequence of using herbicide-based strategies: no herbicide application, full herbicide dose (standard rate) and two reduced dose rates (75 and 50% of the standard rate) to control P. brachystachys in a biennial wheat-sunflower rotation. Simulation results indicated that only herbicide application at a full dose (90% control) and 3/4 dose (80% control) produced positive economic results, with the full dose being the best strategy (EUR 98.65 ha-1 year-1). A sensitivity analysis showed that the economic outcome, in terms of annualized net return, was strongly influenced by changes in yield, price, and fixed costs. In addition, the annualized net return was more sensitive to parameter changes at reduced herbicide doses than at full rate. In the wheat-sunflower rotation system, the application of the full dose of herbicide was the most economical and stable strategy in the long-term. Reduced doses are not a recommended option from an economic point of view. Bioeconomic models provide practical insight into different management approaches for effective weed control.
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Affiliation(s)
- Casto Zambrano-Navea
- Departamento de Agronomia, Facultad de Agronomia, Universidad Central de Venezuela, Maracay 4579, Venezuela;
| | - Fernando Bastida
- Departamento de Ciencias Agroforestales, Universidad de Huelva, 21007 Huelva, Spain;
| | - Maria J. Aguilera
- Departamento de Fisica Aplicada, Universidad de Cordoba, 14071 Cordoba, Spain;
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Husum HC, Hellfritzsch MB, Maimburg RD, Møller-Madsen B, Henriksen M, Lapitskaya N, Kold S, Rahbek O. Pubofemoral distances correlate to acetabular morphology and sonological instability in screening for hip dysplasia. Bone Jt Open 2024; 5:3-8. [PMID: 38164740 PMCID: PMC10758888 DOI: 10.1302/2633-1462.51.bjo-2023-0134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2024] Open
Abstract
Aims The present study seeks to investigate the correlation of pubofemoral distances (PFD) to α angles, and hip displaceability status, defined as femoral head coverage (FHC) or FHC during manual provocation of the newborn hip < 50%. Methods We retrospectively included all newborns referred for ultrasound screening at our institution based on primary risk factor, clinical, and PFD screening. α angles, PFD, FHC, and FHC at follow-up ultrasound for referred newborns were measured and compared using scatter plots, linear regression, paired t-test, and box-plots. Results We included 2,735 newborns, of whom 754 received a follow-up hip ultrasound within six weeks of age. After exclusion, 1,500 hips were included for analysis. Sex distribution was 372 male and 380 female, and the mean age at examination was 36.6 days (4 to 87). We found a negative linear correlation of PFD to α angles (p < 0.001), FHC (p < 0.001), and FHC during provocation (p < 0.001) with a 1 mm increase in PFD corresponding to a -2.1° (95% confidence interval (CI) -2.3 to -1.9) change in α angle and a -3.4% (95% CI -3.7 to -3.0) change in FHC and a -6.0% (-6.6 to -5.5) change in FHC during provocation. The PFD was significantly higher with increasing Graf types and in displaceable hips (p < 0.001). Conclusion PFD is strongly correlated to both α angles and hip displaceability, as measured by FHC and FHC during provocation, in ultrasound of newborn hips. The PFD increases as the hips become more dysplastic and/or displaceable.
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Affiliation(s)
- Hans-Christen Husum
- Interdisciplinary Orthopaedics, Aalborg University Hospital, Aalborg, Denmark
- Danish Paedatric Orthopaedic Research, Aarhus University Hospital, Aarhus, Denmark
| | - Michel B. Hellfritzsch
- Danish Paedatric Orthopaedic Research, Aarhus University Hospital, Aarhus, Denmark
- Department of Radiology, Aarhus University Hospital, Aarhus, Denmark
| | - Rikke D. Maimburg
- Danish Paedatric Orthopaedic Research, Aarhus University Hospital, Aarhus, Denmark
- Department of Children’s Orthopaedics, Aarhus University Hospital, Aarhus, Denmark
| | - Bjarne Møller-Madsen
- Danish Paedatric Orthopaedic Research, Aarhus University Hospital, Aarhus, Denmark
- Department of Midwifery, University College of Northern Denmark, Aalborg East, Denmark
| | - Mads Henriksen
- Danish Paedatric Orthopaedic Research, Aarhus University Hospital, Aarhus, Denmark
- Department of Radiology, Aarhus University Hospital, Aarhus, Denmark
| | - Natallia Lapitskaya
- Danish Paedatric Orthopaedic Research, Aarhus University Hospital, Aarhus, Denmark
- Department of Radiology, Aarhus University Hospital, Aarhus, Denmark
| | - Søren Kold
- Interdisciplinary Orthopaedics, Aalborg University Hospital, Aalborg, Denmark
- Danish Paedatric Orthopaedic Research, Aarhus University Hospital, Aarhus, Denmark
| | - Ole Rahbek
- Interdisciplinary Orthopaedics, Aalborg University Hospital, Aalborg, Denmark
- Danish Paedatric Orthopaedic Research, Aarhus University Hospital, Aarhus, Denmark
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Tesema Z, Derbie B, Shenkute A, Gobeze M, Kefale A, Gizaw S. Breeding objectives for Central Highland goats using participatory and bio-economic modelling approaches. J Anim Breed Genet 2024; 141:1-12. [PMID: 37608464 DOI: 10.1111/jbg.12821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 06/06/2023] [Accepted: 08/12/2023] [Indexed: 08/24/2023]
Abstract
The breeding objectives of Central Highland goats rearing under a low-input production system were defined through a participatory proportional piling method and bio-economic model. Additionally, the economic values and relative economic value of the breeding objective traits were derived. A participatory proportional piling method was used to estimate the relative weights of farmers attached to a list of goat traits identified, and the relative weights were statistically evaluated using a generalized multinomial logit model analysis. A bio-economic model was used to compute the economic values of the identified traits. The most important traits for selection of does according to farmer's preference were body size, coat colour, post-weaning growth rate and weaning rate with a relative weight (odds ratio) of 1.58, 1.38, 1.37 and 1.13, respectively. Goats with dark red followed by light red coat colour were the most preferred (p < 0.001) by goat keepers compared with white-coloured goats. Farmers were more likely (p < 0.001) to allocate higher scores for does-bearing twins than for single and triplet-bearing does. Using the bio-economic model (economic value and relative economic value), post-weaning growth rate, weaning rate, and six-month weight (body size) were identified as the most important traits and if the mean of these traits is changed by one genetic standard deviation, the change in profit will range from 2.06 to 3.03 $ doe-1 year-1 . Therefore, the most important traits for the selection of Central Highland goats according to the economic-based method were post-weaning weight gain, weaning rate and body size (six-month weight). Besides, coat colour was the second preferred trait by goat keepers next to body size. Thus, this aesthetical trait should be included in the designed breeding programme besides economically important quantitative traits. The combination of the participatory proportional piling method and bio-economic model would give better insights to explore the trait preferences of farmers and enhance profitability. The economic values of traits estimated in this study can be used for the construction of selection indices for Central Highland goats.
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Affiliation(s)
- Zeleke Tesema
- Sirinka Agricultural Research Center, Woldia, Ethiopia
| | - Belay Derbie
- Sirinka Agricultural Research Center, Woldia, Ethiopia
| | | | | | - Alemu Kefale
- Sirinka Agricultural Research Center, Woldia, Ethiopia
| | - Solomon Gizaw
- International Livestock Research Institute (ILRI), Addis Ababa, Ethiopia
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Liu YS, Hou P, Wang P, Zhu J. [Research advance on quantitative assessment methods of ecosystem water conservation service functions]. Ying Yong Sheng Tai Xue Bao 2024; 35:275-288. [PMID: 38511465 DOI: 10.13287/j.1001-9332.202401.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
The water conservation service function, which is one of the most important ecological service function in the regional system, directly reflects the regulation role of a region in precipitation, the redistribution function of precipitation, and the ecohydrological value. With the development of the comprehensive evaluation method and the deepening of research on water conservation service function, relevant evaluation calculation process has changed significantly. Nowadays, in the assessment of the water conservation service function, it is necessary not only to calculate and evaluate relevant indicators, but also to localize specific parameters in the model and analyze the effectiveness of the overall model for specific study areas. However, the current literature review lacks systematic summaries of model evaluation methods. Meanwhile, the review is also insufficient on model validity verification and significance analysis methods, the result verification and applicability analysis methods such as parameter localization in water conservation studies. We reviewed the research advance on typical ecosystem water conservation ser-vice assessment methods with a specific focus on the model assessment methods that have developed rapidly in recent years. At the same time, we summarized methods commonly used for parameter localization, as well as validity testing and sensitivity analysis of simulation results, and discussed existing problems and future directions in this field.
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Affiliation(s)
- Yi-Sheng Liu
- Central South University of Forestry and Technology, Changsha 410004, China
- Center for Satellite Application on Ecology and Environment, Ministry of Ecology and Environment, Beijing 100094, China
| | - Peng Hou
- Center for Satellite Application on Ecology and Environment, Ministry of Ecology and Environment, Beijing 100094, China
| | - Ping Wang
- Central South University of Forestry and Technology, Changsha 410004, China
| | - Jian Zhu
- Central South University of Forestry and Technology, Changsha 410004, China
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Zhang L, Cao H, Medlin K, Pearson J, Aristotelous AC, Chen A, Wessler T, Forest MG. Computational Modeling Insights into Extreme Heterogeneity in COVID-19 Nasal Swab Data. Viruses 2023; 16:69. [PMID: 38257769 PMCID: PMC10820884 DOI: 10.3390/v16010069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 12/20/2023] [Accepted: 12/23/2023] [Indexed: 01/24/2024] Open
Abstract
Throughout the COVID-19 pandemic, an unprecedented level of clinical nasal swab data from around the globe has been collected and shared. Positive tests have consistently revealed viral titers spanning six orders of magnitude! An open question is whether such extreme population heterogeneity is unique to SARS-CoV-2 or possibly generic to viral respiratory infections. To probe this question, we turn to the computational modeling of nasal tract infections. Employing a physiologically faithful, spatially resolved, stochastic model of respiratory tract infection, we explore the statistical distribution of human nasal infections in the immediate 48 h of infection. The spread, or heterogeneity, of the distribution derives from variations in factors within the model that are unique to the infected host, infectious variant, and timing of the test. Hypothetical factors include: (1) reported physiological differences between infected individuals (nasal mucus thickness and clearance velocity); (2) differences in the kinetics of infection, replication, and shedding of viral RNA copies arising from the unique interactions between the host and viral variant; and (3) differences in the time between initial cell infection and the clinical test. Since positive clinical tests are often pre-symptomatic and independent of prior infection or vaccination status, in the model we assume immune evasion throughout the immediate 48 h of infection. Model simulations generate the mean statistical outcomes of total shed viral load and infected cells throughout 48 h for each "virtual individual", which we define as each fixed set of model parameters (1) and (2) above. The "virtual population" and the statistical distribution of outcomes over the population are defined by collecting clinically and experimentally guided ranges for the full set of model parameters (1) and (2). This establishes a model-generated "virtual population database" of nasal viral titers throughout the initial 48 h of infection of every individual, which we then compare with clinical swab test data. Support for model efficacy comes from the sampling of infection dynamics over the virtual population database, which reproduces the six-order-of-magnitude clinical population heterogeneity. However, the goal of this study is to answer a deeper biological and clinical question. What is the impact on the dynamics of early nasal infection due to each individual physiological feature or virus-cell kinetic mechanism? To answer this question, global data analysis methods are applied to the virtual population database that sample across the entire database and de-correlate (i.e., isolate) the dynamic infection outcome sensitivities of each model parameter. These methods predict the dominant, indeed exponential, driver of population heterogeneity in dynamic infection outcomes is the latency time of infected cells (from the moment of infection until onset of viral RNA shedding). The shedding rate of the viral RNA of infected cells in the shedding phase is a strong, but not exponential, driver of infection. Furthermore, the unknown timing of the nasal swab test relative to the onset of infection is an equally dominant contributor to extreme population heterogeneity in clinical test data since infectious viral loads grow from undetectable levels to more than six orders of magnitude within 48 h.
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Affiliation(s)
- Leyi Zhang
- Department of Mathematics and Carolina Center for Interdisciplinary Applied Mathematics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Han Cao
- Department of Mathematics and Carolina Center for Interdisciplinary Applied Mathematics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Karen Medlin
- Department of Mathematics and Carolina Center for Interdisciplinary Applied Mathematics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Jason Pearson
- Department of Mathematics and Carolina Center for Interdisciplinary Applied Mathematics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Simulations Plus, Inc., 6 Davis Dr., Durham, NC 27709, USA
| | | | - Alexander Chen
- Department of Mathematics, California State University, Dominguez Hills, CA 90747, USA
| | - Timothy Wessler
- Department of Applied Mathematics, University of Colorado at Boulder, Boulder, CO 80309, USA
| | - M. Gregory Forest
- Department of Mathematics and Carolina Center for Interdisciplinary Applied Mathematics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Departments of Applied Physical Sciences and Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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Farhan M, Shah Z, Jan R, Islam S, Alshehri MH, Ling Z. A fractional modeling approach for the transmission dynamics of measles with double-dose vaccination. Comput Methods Biomech Biomed Engin 2023:1-18. [PMID: 38149815 DOI: 10.1080/10255842.2023.2297171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 11/08/2023] [Indexed: 12/28/2023]
Abstract
Measles, a member of the Paramyxoviridae family and the Morbillivirus genus, is an infectious disease caused by the measles virus that is extremely contagious and can be prevented through vaccination. When a person with the measles coughs or sneezes, the virus is disseminated by respiratory droplets. Normally, the appearance of measles symptoms takes 10-14 d following viral exposure. Conjunctivitis, a high temperature, a cough, a runny nose, and a distinctive rash are some of the symptoms. Despite the measles vaccination being available, it is still widespread worldwide. To eradicate measles, the Reproduction Number (i.e. R 0 < 1 ) must remain less than unity. This study examines a SEIVR compartmental model in the caputo sense using a double dose of vaccine to simulate the measles outbreak. The reproduction number R 0 and model properties are both thoroughly examined. Both the local and global stabilities of the proposed model are determined for R 0 less and greater than 1. To achieve the model's global stability, the Lyapunov function is used while the existence and uniqueness of the proposed model are demonstrated In addition to the calculated and fitted biological parameters, the forward sensitivity indices for R 0 are also obtained. Simulations of the proposed fractional order (FO) caputo model are performed in order to analyse their graphical representations and the significance of FO derivatives to illustrate how our theoretical findings have an impact. The graphical results show that the measles outbreak is reduced by increasing vaccine dosage rates.
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Affiliation(s)
- Muhammad Farhan
- Department of Mathematics, Abdul Wali Khan University Mardan, Khyber Pakhtunkhwa, Pakistan
- School of Mathematical Science, Yangzhou University, Yangzhou, PR China
| | - Zahir Shah
- Department of Mathematical Sciences, University of Lakki Marwat, Lakki Marwat, Pakistan
| | - Rashid Jan
- Department of Mathematics, University of Swabi, Swabi, Pakistan
| | - Saeed Islam
- Department of Mathematics, Abdul Wali Khan University Mardan, Khyber Pakhtunkhwa, Pakistan
| | - Mansoor H Alshehri
- Department of Mathematics, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Zhi Ling
- School of Mathematical Science, Yangzhou University, Yangzhou, PR China
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Zamanian A, Ahmidi N, Drton M. Assessable and interpretable sensitivity analysis in the pattern graph framework for nonignorable missingness mechanisms. Stat Med 2023; 42:5419-5450. [PMID: 37759370 DOI: 10.1002/sim.9920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 06/12/2023] [Accepted: 09/13/2023] [Indexed: 09/29/2023]
Abstract
The pattern graph framework solves a wide range of missing data problems with nonignorable mechanisms. However, it faces two challenges of assessability and interpretability, particularly important in safety-critical problems such as clinical diagnosis: (i) How can one assess the validity of the framework's a priori assumption and make necessary adjustments to accommodate known information about the problem? (ii) How can one interpret the process of exponential tilting used for sensitivity analysis in the pattern graph framework and choose the tilt perturbations based on meaningful real-world quantities? In this paper, we introduce Informed Sensitivity Analysis, an extension of the pattern graph framework that enables us to incorporate substantive knowledge about the missingness mechanism into the pattern graph framework. Our extension allows us to examine the validity of assumptions underlying pattern graphs and interpret sensitivity analysis results in terms of realistic problem characteristics. We apply our method to a prevalent nonignorable missing data scenario in clinical research. We validate and compare our method's results of our method with a number of widely-used missing data methods, including Unweighted CCA, KNN Imputer, MICE, and MissForest. The validation is done using both boot-strapped simulated experiments as well as real-world clinical observations in the MIMIC-III public dataset.
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Affiliation(s)
- Alireza Zamanian
- TUM School of Computation, Information and Technology, Department of Computer Science, Technical University of Munich, Munich, Germany
- Department of Reasoned AI Decisions, Fraunhofer Institute for Cognitive Systems IKS, Munich, Germany
| | - Narges Ahmidi
- Department of Reasoned AI Decisions, Fraunhofer Institute for Cognitive Systems IKS, Munich, Germany
- Institute of Computational Biology, Helmholtz Center Munich, Munich, Germany
| | - Mathias Drton
- TUM School of Computation, Information and Technology, Department of Mathematics, Technical University of Munich, Munich, Germany
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Korsah MA, Johnston ST, Tiedje KE, Day KP, Flegg JA, Walker CR. Mathematical assessment of the role of intervention programs for malaria control. medRxiv 2023:2023.12.18.23300185. [PMID: 38196597 PMCID: PMC10775318 DOI: 10.1101/2023.12.18.23300185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2024]
Abstract
Malaria remains a global health problem despite the many attempts to control and eradicate it. There is an urgent need to understand the current transmission dynamics of malaria and to determine the interventions necessary to control malaria. In this paper, we seek to develop a fit-for-purpose mathematical model to assess the interventions needed to control malaria in an endemic setting. To achieve this, we formulate a malaria transmission model to analyse the spread of malaria in the presence of interventions. A sensitivity analysis of the model is performed to determine the relative impact of the model parameters on disease transmission. We explore how existing variations in the recruitment and management of intervention strategies affect malaria transmission. Results obtained from the study imply that the discontinuation of existing interventions has a significant effect on malaria prevalence. Thus, the maintenance of interventions is imperative for malaria elimination and eradication. In a scenario study aimed at assessing the impact of long-lasting insecticidal nets (LLINs), indoor residual spraying (IRS), and localized individual measures, our findings indicate that increased LLINs utilization and extended IRS coverage (with longer-lasting insecticides) cause a more pronounced reduction in symptomatic malaria prevalence compared to a reduced LLINs utilization and shorter IRS coverage. Additionally, our study demonstrates the impact of localized preventive measures in mitigating the spread of malaria when compared to the absence of interventions.
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Affiliation(s)
- Maame Akua Korsah
- School of Mathematics and Statistics, The University of Melbourne, Melbourne, Australia
| | - Stuart T Johnston
- School of Mathematics and Statistics, The University of Melbourne, Melbourne, Australia
| | - Kathryn E Tiedje
- Department of Microbiology and Immunology, Bio21 Institute and Peter Doherty Institute, The University of Melbourne, Melbourne, Australia
| | - Karen P Day
- Department of Microbiology and Immunology, Bio21 Institute and Peter Doherty Institute, The University of Melbourne, Melbourne, Australia
| | - Jennifer A Flegg
- School of Mathematics and Statistics, The University of Melbourne, Melbourne, Australia
| | - Camelia R Walker
- School of Mathematics and Statistics, The University of Melbourne, Melbourne, Australia
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Petersen JM, Kahrs JC, Adrien N, Wood ME, Olshan AF, Smith LH, Howley MM, Ailes EC, Romitti PA, Herring AH, Parker SE, Shaw GM, Politis MD. Bias analyses to investigate the impact of differential participation: Application to a birth defects case-control study. Paediatr Perinat Epidemiol 2023. [PMID: 38102868 DOI: 10.1111/ppe.13026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 11/17/2023] [Accepted: 11/24/2023] [Indexed: 12/17/2023]
Abstract
BACKGROUND Certain associations observed in the National Birth Defects Prevention Study (NBDPS) contrasted with other research or were from areas with mixed findings, including no decrease in odds of spina bifida with periconceptional folic acid supplementation, moderately increased cleft palate odds with ondansetron use and reduced hypospadias odds with maternal smoking. OBJECTIVES To investigate the plausibility and extent of differential participation to produce effect estimates observed in NBDPS. METHODS We searched the literature for factors related to these exposures and participation and conducted deterministic quantitative bias analyses. We estimated case-control participation and expected exposure prevalence based on internal and external reports, respectively. For the folic acid-spina bifida and ondansetron-cleft palate analyses, we hypothesized the true odds ratio (OR) based on prior studies and quantified the degree of exposure over- (or under-) representation to produce the crude OR (cOR) in NBDPS. For the smoking-hypospadias analysis, we estimated the extent of selection bias needed to nullify the association as well as the maximum potential harmful OR. RESULTS Under our assumptions (participation, exposure prevalence, true OR), there was overrepresentation of folic acid use and underrepresentation of ondansetron use and smoking among participants. Folic acid-exposed spina bifida cases would need to have been ≥1.2× more likely to participate than exposed controls to yield the observed null cOR. Ondansetron-exposed cleft palate cases would need to have been 1.6× more likely to participate than exposed controls if the true OR is null. Smoking-exposed hypospadias cases would need to have been ≥1.2 times less likely to participate than exposed controls for the association to falsely appear protective (upper bound of selection bias adjusted smoking-hypospadias OR = 2.02). CONCLUSIONS Differential participation could partly explain certain associations observed in NBDPS, but questions remain about why. Potential impacts of other systematic errors (e.g. exposure misclassification) could be informed by additional research.
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Affiliation(s)
- Julie M Petersen
- Division for Surveillance, Research, and Promotion of Perinatal Health, Massachusetts Department of Public Health, Boston, Massachusetts, USA
| | - Jacob C Kahrs
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Nedghie Adrien
- Division for Surveillance, Research, and Promotion of Perinatal Health, Massachusetts Department of Public Health, Boston, Massachusetts, USA
- Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts, USA
| | - Mollie E Wood
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Andrew F Olshan
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Louisa H Smith
- Department of Health Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, Massachusetts, USA
- Roux Institute, Northeastern University, Portland, Maine, USA
| | - Meredith M Howley
- Birth Defects Registry, New York State Department of Health, Albany, New York, USA
| | - Elizabeth C Ailes
- National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Paul A Romitti
- Department of Epidemiology, College of Public Health, University of Iowa, Iowa City, Iowa, USA
| | - Amy H Herring
- Department of Statistical Science, Duke University, Durham, North Carolina, USA
| | - Samantha E Parker
- Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts, USA
| | - Gary M Shaw
- Division of Neonatology, Department of Pediatrics, Stanford University School of Medicine, Stanford, California, USA
| | - Maria D Politis
- Arkansas Center for Birth Defects Research and Prevention, Fay W. Boozman College of Public Health, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
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Díaz I, Lee H, Kıcıman E, Schenck EJ, Akacha M, Follman D, Ghosh D. Sensitivity analysis for causality in observational studies for regulatory science. J Clin Transl Sci 2023; 7:e267. [PMID: 38380390 PMCID: PMC10877517 DOI: 10.1017/cts.2023.688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 10/30/2023] [Accepted: 11/16/2023] [Indexed: 02/22/2024] Open
Abstract
Objective The United States Congress passed the 21st Century Cures Act mandating the development of Food and Drug Administration guidance on regulatory use of real-world evidence. The Forum on the Integration of Observational and Randomized Data conducted a meeting with various stakeholder groups to build consensus around best practices for the use of real-world data (RWD) to support regulatory science. Our companion paper describes in detail the context and discussion of the meeting, which includes a recommendation to use a causal roadmap for study designs using RWD. This article discusses one step of the roadmap: the specification of a sensitivity analysis for testing robustness to violations of causal model assumptions. Methods We present an example of a sensitivity analysis from a RWD study on the effectiveness of Nifurtimox in treating Chagas disease, and an overview of various methods, emphasizing practical considerations on their use for regulatory purposes. Results Sensitivity analyses must be accompanied by careful design of other aspects of the causal roadmap. Their prespecification is crucial to avoid wrong conclusions due to researcher degrees of freedom. Sensitivity analysis methods require auxiliary information to produce meaningful conclusions; it is important that they have at least two properties: the validity of the conclusions does not rely on unverifiable assumptions, and the auxiliary information required by the method is learnable from the corpus of current scientific knowledge. Conclusions Prespecified and assumption-lean sensitivity analyses are a crucial tool that can strengthen the validity and trustworthiness of effectiveness conclusions for regulatory science.
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Affiliation(s)
- Iván Díaz
- Division of Biostatistics, Department of Population Health,
New York University Grossman School of Medicine, New
York, NY, USA
| | - Hana Lee
- Office of Biostatistics, Office of Translational Sciences, Center for Drug
Evaluation and Research, U.S. Food and Drug Administration, Silver
Spring, MD, USA
| | | | | | | | - Dean Follman
- Biostatistics Research Branch, National Institute of Allergy and Infectious
Disease, Silver Spring, MD,
USA
| | - Debashis Ghosh
- Department of Biostatistics and Informatics, Colorado School
of Public Health, University of Colorado Anschutz Medical Campus,
Colorado, USA
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45
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Omari Shekaftik S, Nasirzadeh N, Mohammadiyan M, Mohammadpour S. An analysis on control banding-based methods used for occupational risk assessment of nanomaterials. Nanotoxicology 2023; 17:628-650. [PMID: 38164113 DOI: 10.1080/17435390.2023.2293141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 12/05/2023] [Indexed: 01/03/2024]
Abstract
Despite all benefits of nanomaterials, their unique characteristics made them an emerging hazard in workplaces, which need to be assessed for their potential risks. So, the aim of this study was to review all the studies conducted on the risk assessment of activities involving nanomaterials with CB-based methods.This study is based on a literature review on databases including Web of science, Scopus, PubMed, and SID. After reviewing and screening studies according to PRISMA, the collected data were meta-analyzed by Comprehensive Meta-Analysis Software. Also, Newcastle-Ottawa checklist was used for quality assessment of the studies. To determine similarity of methods, Cohen's Kappa was used. Sensitivity analysis was used to determine the role of each factor in the risk assessment by using the Crystal Ball tool.There are eight validated methods for risk assessment. Also, some authors used a self-deigned tool based on CB approach. The results of meta-analysis showed that the odds ratio for the risk of activities involved with nanomaterials was 0.654 (high risk). Results of simulation for Nanotool showed that the mean risk level of activities involved with nanomaterials, with a certainty of 95.07%, is moderate (RL3). Moreover, sensitivity analysis showed that the risk was depended on "Hazard band" in all methods except ISO method.The obtained results can be useful in improving existing methods and suggesting new methods. Also, there is a need to design and propose specific methods for risk assessment of incidental and natural nanomaterials.
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Affiliation(s)
- Soqrat Omari Shekaftik
- School of Public Health, Department of Occupational Health Engineering, Tehran University of Medical Sciences, Tehran, Iran
| | - Nafiseh Nasirzadeh
- School of Public Health, Department of Occupational Health Engineering, Tehran University of Medical Sciences, Tehran, Iran
| | - Mahdi Mohammadiyan
- School of Public Health, Department of Occupational Health Engineering, Tehran University of Medical Sciences, Tehran, Iran
| | - Saman Mohammadpour
- School of Allied Medical Sciences, Department of Health Information Management and Technology, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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46
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Rosenbaum PR. A second evidence factor for a second control group. Biometrics 2023; 79:3968-3980. [PMID: 37563803 DOI: 10.1111/biom.13921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 07/24/2023] [Indexed: 08/12/2023]
Abstract
In an observational study of the effects caused by a treatment, a second control group is used in an effort to detect bias from unmeasured covariates, and the investigator is content if no evidence of bias is found. This strategy is not entirely satisfactory: two control groups may differ significantly, yet the difference may be too small to invalidate inferences about the treatment, or the control groups may not differ yet nonetheless fail to provide a tangible strengthening of the evidence of a treatment effect. Is a firmer conclusion possible? Is there a way to analyze a second control group such that the data might report measurably strengthened evidence of cause and effect, that is, insensitivity to larger unmeasured biases? Evidence factor analyses are not commonly used with a second control group: most analyses compare the treated group to each control group, but analyses of that kind are partially redundant; so, they do not constitute evidence factors. An alternative analysis is proposed here, one that does yield two evidence factors, and with a carefully designed test statistic, is capable of extracting strong evidence from the second factor. The new technical work here concerns the development of a test statistic with high design sensitivity and high Bahadur efficiency in a sensitivity analysis for the second factor. A study of binge drinking as a cause of high blood pressure is used as an illustration.
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Affiliation(s)
- Paul R Rosenbaum
- Department of Statistics and Data Science, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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47
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Rosenman ETR, Basse G, Owen AB, Baiocchi M. Combining observational and experimental datasets using shrinkage estimators. Biometrics 2023; 79:2961-2973. [PMID: 36629736 DOI: 10.1111/biom.13827] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Accepted: 01/04/2023] [Indexed: 01/12/2023]
Abstract
We consider the problem of combining data from observational and experimental sources to draw causal conclusions. To derive combined estimators with desirable properties, we extend results from the Stein shrinkage literature. Our contributions are threefold. First, we propose a generic procedure for deriving shrinkage estimators in this setting, making use of a generalized unbiased risk estimate. Second, we develop two new estimators, prove finite sample conditions under which they have lower risk than an estimator using only experimental data, and show that each achieves a notion of asymptotic optimality. Third, we draw connections between our approach and results in sensitivity analysis, including proposing a method for evaluating the feasibility of our estimators.
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Affiliation(s)
- Evan T R Rosenman
- Harvard Data Science Initiative, Harvard University, Cambridge, Massachusetts, USA
| | | | - Art B Owen
- Department of Statistics, Stanford University, Stanford, California, USA
| | - Mike Baiocchi
- Department of Statistics, Stanford University, Stanford, California, USA
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48
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Linero AR. Prior and posterior checking of implicit causal assumptions. Biometrics 2023; 79:3153-3164. [PMID: 37325868 DOI: 10.1111/biom.13886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 05/18/2023] [Indexed: 06/17/2023]
Abstract
Causal inference practitioners have increasingly adopted machine learning techniques with the aim of producing principled uncertainty quantification for causal effects while minimizing the risk of model misspecification. Bayesian nonparametric approaches have attracted attention as well, both for their flexibility and their promise of providing natural uncertainty quantification. Priors on high-dimensional or nonparametric spaces, however, can often unintentionally encode prior information that is at odds with substantive knowledge in causal inference-specifically, the regularization required for high-dimensional Bayesian models to work can indirectly imply that the magnitude of the confounding is negligible. In this paper, we explain this problem and provide tools for (i) verifying that the prior distribution does not encode an inductive bias away from confounded models and (ii) verifying that the posterior distribution contains sufficient information to overcome this issue if it exists. We provide a proof-of-concept on simulated data from a high-dimensional probit-ridge regression model, and illustrate on a Bayesian nonparametric decision tree ensemble applied to a large medical expenditure survey.
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Affiliation(s)
- Antonio R Linero
- Department of Statistics and Data Science, University of Texas at Austin, Austin, Texas, USA
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49
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Yang Y, Lubin M, Zhou Z, Niu K. An Analysis of Honeybee Population Dynamics. Stud Health Technol Inform 2023; 308:76-85. [PMID: 38007728 DOI: 10.3233/shti230827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2023]
Abstract
Colony Collapse disorder (the CCD) is the term used to describe the global decline in bee populations. The research mission of this article is to identify which factors contribute to the CCD and understand how these factors contribute to the decline of bee populations, which may provide methods for restoring global bee populations. Two parts of the study will be mentioned in this article. The first half of our study was to understand such collective intelligence (and habits such as seasonal behavioral change) and use a mathematical model to simulate it. We then input the variables that we used to simulate honeybee collective intelligence into a time-dependent model to predict the population of a honey colony over time. In this model, we excluded the factors that might cause the CCD on purpose, so we could use it as a controlled set of honeybee natural population dynamics. We compared the results of this population model to experimental data we found, and they matched within certain degrees. The second half of our study was to perform a sensitivity analysis by introducing back the three factors that might cause the CCD to the population model including climate change, pesticides, and habitat destruction. The paper further discussed the strength and weaknesses of the mathematical model and used this model to predict how many honeybee hives were needed to support the pollination of a 20-acre parcel of land containing crops that benefit from pollination. Additionally, an infographic of our method was illustrated.
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Affiliation(s)
- Yicheng Yang
- Byram Hills High School, 10 Tripp Lane, Armonk, NY 10504 United States
| | - Mia Lubin
- Marjory Stoneman Douglas High School, 5901 Pine Island Rd, Parkland, FL 33076, United States
| | - Ziyao Zhou
- Brownell Talbot College Preparatory School, 400 N. Happy Hollow Blvd., Omaha, NE 68132 United States
| | - Kevin Niu
- Jericho High School, 99 Cedar Swamp Road, Jericho, NY 11753 United States
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50
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Borgiani E, Nasello G, Ory L, Herpelinck T, Groeneveldt L, Bucher CH, Schmidt-Bleek K, Geris L. COMMBINI: an experimentally-informed COmputational Model of Macrophage dynamics in the Bone INjury Immunoresponse. Front Immunol 2023; 14:1231329. [PMID: 38130715 PMCID: PMC10733790 DOI: 10.3389/fimmu.2023.1231329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 10/11/2023] [Indexed: 12/23/2023] Open
Abstract
Bone fracture healing is a well-orchestrated but complex process that involves numerous regulations at different scales. This complexity becomes particularly evident during the inflammatory stage, as immune cells invade the healing region and trigger a cascade of signals to promote a favorable regenerative environment. Thus, the emergence of criticalities during this stage might hinder the rest of the process. Therefore, the investigation of the many interactions that regulate the inflammation has a primary importance on the exploration of the overall healing progression. In this context, an in silico model named COMMBINI (COmputational Model of Macrophage dynamics in the Bone INjury Immunoresponse) has been developed to investigate the mechano-biological interactions during the early inflammatory stage at the tissue, cellular and molecular levels. An agent-based model is employed to simulate the behavior of immune cells, inflammatory cytokines and fracture debris as well as their reciprocal multiscale biological interactions during the development of the early inflammation (up to 5 days post-injury). The strength of the computational approach is the capacity of the in silico model to simulate the overall healing process by taking into account the numerous hidden events that contribute to its success. To calibrate the model, we present an in silico immunofluorescence method that enables a direct comparison at the cellular level between the model output and experimental immunofluorescent images. The combination of sensitivity analysis and a Genetic Algorithm allows dynamic cooperation between these techniques, enabling faster identification of the most accurate parameter values, reducing the disparity between computer simulation and histological data. The sensitivity analysis showed a higher sensibility of the computer model to the macrophage recruitment ratio during the early inflammation and to proliferation in the late stage. Furthermore, the Genetic Algorithm highlighted an underestimation of macrophage proliferation by in vitro experiments. Further experiments were conducted using another externally fixated murine model, providing an independent validation dataset. The validated COMMBINI platform serves as a novel tool to deepen the understanding of the intricacies of the early bone regeneration phases. COMMBINI aims to contribute to designing novel treatment strategies in both the biological and mechanical domains.
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Affiliation(s)
- Edoardo Borgiani
- Biomechanics Research Unit, GIGA-In Silico Medicine, University of Liège, Liège, Belgium
- Prometheus, Division of Skeletal Tissue Engineering, KU Leuven, Leuven, Belgium
- Division of Biomechanics, Department of Mechanical Engineering, KU Leuven, Leuven, Belgium
| | - Gabriele Nasello
- Prometheus, Division of Skeletal Tissue Engineering, KU Leuven, Leuven, Belgium
- Skeletal Biology and Engineering Research Center, KU Leuven, Leuven, Belgium
| | - Liesbeth Ory
- Prometheus, Division of Skeletal Tissue Engineering, KU Leuven, Leuven, Belgium
- Skeletal Biology and Engineering Research Center, KU Leuven, Leuven, Belgium
| | - Tim Herpelinck
- Prometheus, Division of Skeletal Tissue Engineering, KU Leuven, Leuven, Belgium
- Skeletal Biology and Engineering Research Center, KU Leuven, Leuven, Belgium
| | - Lisanne Groeneveldt
- Prometheus, Division of Skeletal Tissue Engineering, KU Leuven, Leuven, Belgium
- Skeletal Biology and Engineering Research Center, KU Leuven, Leuven, Belgium
- Department of Cell Biology, Erasmus University Medical Center, Rotterdam, Netherlands
| | - Christian H. Bucher
- Julius Wolff Institute, Berlin Institute of Health, Charitè – Universitätsmedizin Berlin, Berlin, Germany
| | - Katharina Schmidt-Bleek
- Julius Wolff Institute, Berlin Institute of Health, Charitè – Universitätsmedizin Berlin, Berlin, Germany
| | - Liesbet Geris
- Biomechanics Research Unit, GIGA-In Silico Medicine, University of Liège, Liège, Belgium
- Prometheus, Division of Skeletal Tissue Engineering, KU Leuven, Leuven, Belgium
- Division of Biomechanics, Department of Mechanical Engineering, KU Leuven, Leuven, Belgium
- Skeletal Biology and Engineering Research Center, KU Leuven, Leuven, Belgium
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