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Anguelov R, Manjunath G, Phiri AE, Nyakudya TT, Bipath P, C Serem J, N Hlophe Y. Quantifying assays: inhibition of signalling pathways of cancer. Math Med Biol 2023; 40:266-290. [PMID: 37669569 DOI: 10.1093/imammb/dqad005] [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: 09/12/2022] [Revised: 02/24/2023] [Accepted: 08/25/2023] [Indexed: 09/07/2023]
Abstract
Inhibiting a signalling pathway concerns controlling the cellular processes of a cancer cell's viability, cell division and death. Assay protocols created to see if the molecular structures of the drugs being tested have the desired inhibition qualities often show great variability across experiments, and it is imperative to diminish the effects of such variability while inferences are drawn. In this paper, we propose the study of experimental data through the lenses of a mathematical model depicting the inhibition mechanism and the activation-inhibition dynamics. The method is exemplified through assay data obtained from an experimental study of the inhibition of the chemokine receptor 4 (CXCR4) and chemokine ligand 12 (CXCL12) signalling pathway of melanoma cells. The quantitative analysis is conducted as a two step process: (i) deriving theoretically from the model the cell viability as a function of time depending on several parameters; (ii) estimating the values of the parameters by using the experimental data. The cell viability is obtained as a function of concentration of the inhibitor and time, thus providing a comprehensive characterization of the potential therapeutic effect of the considered inhibitor, e.g. $IC_{50}$ can be computed for any time point.
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Affiliation(s)
- Roumen Anguelov
- Department of Mathematics and Applied Mathematics, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
- Institute of Mathematics and Informatics, Bulgarian Academy of Sciences, Acad. Georgi Bonchev St., Block 8, Sofia 1113, Bulgaria
| | - G Manjunath
- Department of Mathematics and Applied Mathematics, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Avulundiah E Phiri
- Department of Mathematics and Applied Mathematics, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Trevor T Nyakudya
- Department of Physiology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Priyesh Bipath
- Department of Physiology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - June C Serem
- Department of Anatomy, University of Pretoria, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Yvette N Hlophe
- Department of Physiology, University of Pretoria, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
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2
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Hansen J, Siddiq MM, Yadaw AS, Tolentino RE, Rabinovich V, Jayaraman G, Jain MR, Liu T, Li H, Xiong Y, Goldfarb J, Iyengar R. Whole cell response to receptor stimulation involves many deep and distributed subcellular biochemical processes. J Biol Chem 2022; 298:102325. [PMID: 35926710 PMCID: PMC9520007 DOI: 10.1016/j.jbc.2022.102325] [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: 03/14/2022] [Revised: 07/26/2022] [Accepted: 07/27/2022] [Indexed: 11/28/2022] Open
Abstract
Neurite outgrowth is an integrated whole cell response triggered by the cannabinoid-1 receptor. We sought to identify the many different biochemical pathways that contribute to this whole cell response. To understand underlying mechanisms, we identified subcellular processes (SCPs) composed of one or more biochemical pathways and their interactions required for this response. Differentially expressed genes and proteins were obtained from bulk transcriptomics and proteomic analysis of extracts from cells stimulated with a cannabinoid-1 receptor agonist. We used these differentially expressed genes and proteins to build networks of interacting SCPs by combining the expression data with prior pathway knowledge. From these SCP networks, we identified additional genes that when ablated, experimentally validated the SCP involvement in neurite outgrowth. Our experiments and informatics modeling allowed us to identify diverse SCPs such as those involved in pyrimidine metabolism, lipid biosynthesis, and mRNA splicing and stability, along with more predictable SCPs such as membrane vesicle transport and microtubule dynamics. We find that SCPs required for neurite outgrowth are widely distributed among many biochemical pathways required for constitutive cellular functions, several of which are termed ‘deep’, since they are distal to signaling pathways and the key SCPs directly involved in extension of the neurite. In contrast, ‘proximal’ SCPs are involved in microtubule growth and membrane vesicle transport dynamics required for neurite outgrowth. From these bioinformatics and dynamical models based on experimental data, we conclude that receptor-mediated regulation of subcellular functions for neurite outgrowth is both distributed, that is, involves many different biochemical pathways, and deep.
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Affiliation(s)
- Jens Hansen
- Department of Pharmacological Sciences and Institute for Systems Biomedicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Mustafa M Siddiq
- Department of Pharmacological Sciences and Institute for Systems Biomedicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Arjun Singh Yadaw
- Department of Pharmacological Sciences and Institute for Systems Biomedicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Rosa E Tolentino
- Department of Pharmacological Sciences and Institute for Systems Biomedicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Vera Rabinovich
- Department of Pharmacological Sciences and Institute for Systems Biomedicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Gomathi Jayaraman
- Department of Pharmacological Sciences and Institute for Systems Biomedicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Mohit Raja Jain
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers University, New Jersey Medical School, Newark, NY, 07103, United States
| | - Tong Liu
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers University, New Jersey Medical School, Newark, NY, 07103, United States
| | - Hong Li
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers University, New Jersey Medical School, Newark, NY, 07103, United States
| | - Yuguang Xiong
- Department of Pharmacological Sciences and Institute for Systems Biomedicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Joseph Goldfarb
- Department of Pharmacological Sciences and Institute for Systems Biomedicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Ravi Iyengar
- Department of Pharmacological Sciences and Institute for Systems Biomedicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States.
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3
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Ackley SF, Lessler J, Glymour MM. Dynamical Modeling as a Tool for Inferring Causation. Am J Epidemiol 2022; 191:1-6. [PMID: 34447984 DOI: 10.1093/aje/kwab222] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 08/16/2021] [Accepted: 08/18/2021] [Indexed: 01/04/2023] Open
Abstract
Dynamical models, commonly used in infectious disease epidemiology, are formal mathematical representations of time-changing systems or processes. For many chronic disease epidemiologists, the link between dynamical models and predominant causal inference paradigms is unclear. In this commentary, we explain the use of dynamical models for representing causal systems and the relevance of dynamical models for causal inference. In certain simple settings, dynamical modeling and conventional statistical methods (e.g., regression-based methods) are equivalent, but dynamical modeling has advantages over conventional statistical methods for many causal inference problems. Dynamical models can be used to transparently encode complex biological knowledge, interference and spillover, effect modification, and variables that influence each other in continuous time. As our knowledge of biological and social systems and access to computational resources increases, there will be growing utility for a variety of mathematical modeling tools in epidemiology.
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Lee J, Park K. Modeling cycling performance: Effects of saddle position and cadence on cycle pedaling efficiency. Sci Prog 2021; 104:368504211041495. [PMID: 34612733 PMCID: PMC10450785 DOI: 10.1177/00368504211041495] [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: 11/16/2022]
Abstract
The modeling method is an effective means of estimating causality as well as examining cycle pedaling efficiency. Pedaling efficiency can also be examined by an experimental method, but the experimental method can lead to contradictory results due to perturbation of the measured output parameters. Experimental studies generally yield realistic results, but it is difficult to control for all the variables of interest and to determine the causal relationships between them. The objective of this study is to investigate the pedaling efficiency and causality with considering saddle position and pedaling cadence as variables. Based on the mathematical pedaling modeling, the internal work calculation method was used to calculate the consumed mechanical energy and energy conservation percentage (C s ). The optimal saddle position with the lowest mechanical energy and the highest energy conservation percentage could be changed by the cadence. At the low cadence, the higher saddle position, and the shorter horizontal distance between the saddle and crankshaft led to higher pedaling efficiency (h: 0.95 m, d: 0.16 m, and knee angle: 28 ° ). However, the highest pedaling efficiency was achieved at the high cadence with a saddle height (h) of 0.9 m and a horizontal distance between the saddle and the crankshaft (d) of 0.06 m (knee angle: 48 ° ). The lowest cadence is the optimal cadence in terms of the consumed energy, but the optimal cadence was 90 r/min in terms of the energy conservation percentage. Compared to the energy consumption, the energy conservation percentage was demonstrated to influence the fatigue of a cycle rider more critically. The energy conservation percentage was highest at 90 r/min, and 90 r/min was close to the preferred cadence by the cyclist.
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Affiliation(s)
- JongRok Lee
- Department of Mechatronics Engineering, Incheon National University, South Korea
| | - Kiwon Park
- Department of Mechatronics Engineering, Incheon National University, South Korea
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Martín CA, Rivera DE, Hekler EB, Riley WT, Buman MP, Adams MA, Magann AB. Development of a Control-Oriented Model of Social Cognitive Theory for Optimized mHealth Behavioral Interventions. IEEE Trans Control Syst Technol 2020; 28:331-346. [PMID: 33746479 PMCID: PMC7977327 DOI: 10.1109/tcst.2018.2873538] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Mobile health (mHealth) technologies are contributing to the increasing relevance of control engineering principles in understanding and improving health behaviors, such as physical activity. Social Cognitive Theory (SCT), one of the most influential theories of health behavior, has been used as the conceptual basis for behavioral interventions for smoking cessation, weight management, and other health-related outcomes. This paper presents a control-oriented dynamical systems model of SCT based on fluid analogies that can be used in system identification and control design problems relevant to the design and analysis of intensively adaptive interventions. Following model development, a series of simulation scenarios illustrating the basic workings of the model are presented. The model's usefulness is demonstrated in the solution of two important practical problems: 1) semiphysical model estimation from data gathered in a physical activity intervention (the MILES study) and 2) as a means for discerning the range of "ambitious but doable" daily step goals in a closed-loop behavioral intervention aimed at sedentary adults. The model is the basis for ongoing experimental validation efforts, and should encourage additional research in applying control engineering technologies to the social and behavioral sciences.
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Affiliation(s)
- César A Martín
- ESPOL Polytechnic University, Escuela Superior Politécnica del Litoral, ESPOL, Facultad de Ingeniería en Electricidad y Computacion, Campus Gustavo Galindo Km. 30.5 Vía Perimetral, P.O. Box 09-01-5863, Guayaquil, Ecuador
| | - Daniel E Rivera
- Control Systems Engineering Laboratory (CSEL), School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, AZ, USA
| | - Eric B Hekler
- Center for Wireless and Population Health Systems and the Department of Family Medicine and Public Health, University of California at San Diego, CA, USA
| | - William T Riley
- Office of Behavioral and Social Sciences Research, National Institutes of Health, Bethesda, MD, USA
| | - Matthew P Buman
- School of Nutrition and Health Promotion, Arizona State University, Phoenix, AZ, USA
| | - Marc A Adams
- School of Nutrition and Health Promotion, Arizona State University, Phoenix, AZ, USA
| | - Alicia B Magann
- Control Systems Engineering Laboratory (CSEL), School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, AZ, USA
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Abstract
Human immunodeficiency virus infection is still one of the most important causes of morbidity and mortality in the world, with a disproportionate human and economic burden especially in poorer countries. Despite many years of intense research, an aspect that still is not well understood is what (immune) mechanisms control the viral load during the prolonged asymptomatic stage of infection. Because CD8+ T cells have been implicated in this control by multiple lines of evidence, there has been a focus on understanding the potential mechanisms of action of this immune effector population. One type of experiment used to this end has been depleting these cells with monoclonal antibodies in the simian immunodeficiency virus-macaque model and then studying the effect of that depletion on the viral dynamics. Here we review what these experiments have told us. We emphasize modeling studies to interpret the changes in viral load observed in these experiments, including discussion of alternative models, assumptions and interpretations, as well as potential future experiments.
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Affiliation(s)
- Erwing Fabian Cardozo
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington
| | - Cristian Apetrei
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Ivona Pandrea
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Ruy M Ribeiro
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, New Mexico.,Laboratorio de Biomatematica, Faculdade de Medicina da Universidade de Lisboa, Portugal
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7
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Collombet S, van Oevelen C, Sardina Ortega JL, Abou-Jaoudé W, Di Stefano B, Thomas-Chollier M, Graf T, Thieffry D. Logical modeling of lymphoid and myeloid cell specification and transdifferentiation. Proc Natl Acad Sci U S A 2017; 114:5792-9. [PMID: 28584084 DOI: 10.1073/pnas.1610622114] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Blood cells are derived from a common set of hematopoietic stem cells, which differentiate into more specific progenitors of the myeloid and lymphoid lineages, ultimately leading to differentiated cells. This developmental process is controlled by a complex regulatory network involving cytokines and their receptors, transcription factors, and chromatin remodelers. Using public data and data from our own molecular genetic experiments (quantitative PCR, Western blot, EMSA) or genome-wide assays (RNA-sequencing, ChIP-sequencing), we have assembled a comprehensive regulatory network encompassing the main transcription factors and signaling components involved in myeloid and lymphoid development. Focusing on B-cell and macrophage development, we defined a qualitative dynamical model recapitulating cytokine-induced differentiation of common progenitors, the effect of various reported gene knockdowns, and the reprogramming of pre-B cells into macrophages induced by the ectopic expression of specific transcription factors. The resulting network model can be used as a template for the integration of new hematopoietic differentiation and transdifferentiation data to foster our understanding of lymphoid/myeloid cell-fate decisions.
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Bekele-Maxwell K, Everett RA, Shao S, Kuerbis A, Stephenson L, Banks HT, Morgenstern J. Dynamical Systems Modeling to Identify a Cohort of Problem Drinkers with Similar Mechanisms of Behavior Change. J Pers Oriented Res 2017; 3:101-118. [PMID: 33569127 PMCID: PMC7869621 DOI: 10.17505/jpor.2017.09] [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] [Indexed: 11/06/2022] Open
Abstract
One challenge to understanding mechanisms of behavior change (MOBC) completely among individuals with alcohol use disorder is that processes of change are theorized to be complex, dynamic (time varying), and at times non-linear, and they interact with each other to influence alcohol consumption. We used dynamical systems modeling to better understand MOBC within a cohort of problem drinkers undergoing treatment. We fit a mathematical model to ecological momentary assessment data from individual patients who successfully reduced their drinking by the end of the treatment. The model solutions agreed with the trend of the data reasonably well, suggesting the cohort patients have similar MOBC. This work demonstrates using a personalized approach to psychological research, which complements standard statistical approaches that are often applied at the population level.
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Affiliation(s)
| | - R A Everett
- Center for Research in Scientific Computation, North Carolina State University
| | | | | | - Lyric Stephenson
- Center for Research in Scientific Computation, North Carolina State University
| | - H T Banks
- Center for Research in Scientific Computation, North Carolina State University
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9
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Nalepka P, Kallen RW, Chemero A, Saltzman E, Richardson MJ. Herd Those Sheep: Emergent Multiagent Coordination and Behavioral-Mode Switching. Psychol Sci 2017; 28:630-650. [PMID: 28375693 DOI: 10.1177/0956797617692107] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Effectively coordinating one's behaviors with those of others is essential for successful multiagent activity. In recent years, increased attention has been given to understanding the dynamical principles that underlie such coordination because of a growing interest in behavioral synchrony and complex-systems phenomena. Here, we examined the behavioral dynamics of a novel, multiagent shepherding task, in which pairs of individuals had to corral small herds of virtual sheep in the center of a virtual game field. Initially, all pairs adopted a complementary, search-and-recover mode of behavioral coordination, in which both members corralled sheep predominantly on their own sides of the field. Over the course of game play, however, a significant number of pairs spontaneously discovered a more effective mode of behavior: coupled oscillatory containment, in which both members synchronously oscillated around the sheep. Analysis and modeling revealed that both modes were defined by the task's underlying dynamics and, moreover, reflected context-specific realizations of the lawful dynamics that define functional shepherding behavior more generally.
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Affiliation(s)
- Patrick Nalepka
- 1 Center for Cognition, Action & Perception, University of Cincinnati
| | - Rachel W Kallen
- 1 Center for Cognition, Action & Perception, University of Cincinnati
| | - Anthony Chemero
- 1 Center for Cognition, Action & Perception, University of Cincinnati
| | - Elliot Saltzman
- 2 Department of Physical Therapy & Athletic Training, Sargent College of Health & Rehabilitation Sciences, Boston University.,3 Haskins Laboratories, New Haven, CT
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Crauste F, Mafille J, Boucinha L, Djebali S, Gandrillon O, Marvel J, Arpin C. Identification of Nascent Memory CD8 T Cells and Modeling of Their Ontogeny. Cell Syst 2017; 4:306-317.e4. [PMID: 28237797 DOI: 10.1016/j.cels.2017.01.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [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: 04/01/2016] [Revised: 07/21/2016] [Accepted: 01/20/2017] [Indexed: 02/07/2023]
Abstract
Primary immune responses generate short-term effectors and long-term protective memory cells. The delineation of the genealogy linking naive, effector, and memory cells has been complicated by the lack of phenotypes discriminating effector from memory differentiation stages. Using transcriptomics and phenotypic analyses, we identify Bcl2 and Mki67 as a marker combination that enables the tracking of nascent memory cells within the effector phase. We then use a formal approach based on mathematical models describing the dynamics of population size evolution to test potential progeny links and demonstrate that most cells follow a linear naive→early effector→late effector→memory pathway. Moreover, our mathematical model allows long-term prediction of memory cell numbers from a few early experimental measurements. Our work thus provides a phenotypic means to identify effector and memory cells, as well as a mathematical framework to investigate their genealogy and to predict the outcome of immunization regimens in terms of memory cell numbers generated.
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Affiliation(s)
- Fabien Crauste
- Team Dracula, Inria, 69603 Villeurbanne, France; Institut Camille Jordan, Université de Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5208, 43 Boulevard du 11 novembre 1918, 69622 Villeurbanne Cedex, France
| | - Julien Mafille
- CIRI, ICL, INSERM U1111, Université Claude Bernard Lyon 1, CNRS UMR 5308, École Normale Supérieure de Lyon, Université de Lyon, 69007 Lyon, France
| | - Lilia Boucinha
- CIRI, ICL, INSERM U1111, Université Claude Bernard Lyon 1, CNRS UMR 5308, École Normale Supérieure de Lyon, Université de Lyon, 69007 Lyon, France
| | - Sophia Djebali
- CIRI, ICL, INSERM U1111, Université Claude Bernard Lyon 1, CNRS UMR 5308, École Normale Supérieure de Lyon, Université de Lyon, 69007 Lyon, France
| | - Olivier Gandrillon
- Team Dracula, Inria, 69603 Villeurbanne, France; Laboratory of Biology and Modelling of the Cell, Université de Lyon, ENS de Lyon, Université Claude Bernard, CNRS UMR 5239, INSERM U1210, 46 allée d'Italie Site Jacques Monod, 69007 Lyon, France
| | - Jacqueline Marvel
- CIRI, ICL, INSERM U1111, Université Claude Bernard Lyon 1, CNRS UMR 5308, École Normale Supérieure de Lyon, Université de Lyon, 69007 Lyon, France.
| | - Christophe Arpin
- CIRI, ICL, INSERM U1111, Université Claude Bernard Lyon 1, CNRS UMR 5308, École Normale Supérieure de Lyon, Université de Lyon, 69007 Lyon, France.
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Huo X, Feng S, Liu K, Wang L, Chen W. Aerodynamic Drag Analysis of 3-DOF Flex-Gimbal GyroWheel System in the Sense of Ground Test. Sensors (Basel) 2016; 16:s16122081. [PMID: 27941602 PMCID: PMC5191062 DOI: 10.3390/s16122081] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 11/11/2016] [Accepted: 12/02/2016] [Indexed: 11/16/2022]
Abstract
GyroWheel is an innovative device that combines the actuating capabilities of a control moment gyro with the rate sensing capabilities of a tuned rotor gyro by using a spinning flex-gimbal system. However, in the process of the ground test, the existence of aerodynamic disturbance is inevitable, which hinders the improvement of the specification performance and control accuracy. A vacuum tank test is a possible candidate but is sometimes unrealistic due to the substantial increase in costs and complexity involved. In this paper, the aerodynamic drag problem with respect to the 3-DOF flex-gimbal GyroWheel system is investigated by simulation analysis and experimental verification. Concretely, the angular momentum envelope property of the spinning rotor system is studied and its integral dynamical model is deduced based on the physical configuration of the GyroWheel system with an appropriately defined coordinate system. In the sequel, the fluid numerical model is established and the model geometries are checked with FLUENT software. According to the diversity and time-varying properties of the rotor motions in three-dimensions, the airflow field around the GyroWheel rotor is analyzed by simulation with respect to its varying angular velocity and tilt angle. The IPC-based experimental platform is introduced, and the properties of aerodynamic drag in the ground test condition are obtained through comparing the simulation with experimental results.
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Affiliation(s)
- Xin Huo
- Control and Simulation Center, Harbin Institute of Technology, Harbin 150080, China.
| | - Sizhao Feng
- Control and Simulation Center, Harbin Institute of Technology, Harbin 150080, China.
| | - Kangzhi Liu
- Department of Electrical and Electronic Engineering, Chiba University, Chiba 263-8522, Japan.
| | - Libin Wang
- Control and Simulation Center, Harbin Institute of Technology, Harbin 150080, China.
| | - Weishan Chen
- School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150080, China.
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12
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Kuijper IA, Yang H, Van De Water B, Beltman JB. Unraveling cellular pathways contributing to drug-induced liver injury by dynamical modeling. Expert Opin Drug Metab Toxicol 2016; 13:5-17. [PMID: 27609146 DOI: 10.1080/17425255.2017.1234607] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
INTRODUCTION Drug-induced liver injury (DILI) is a significant threat to human health and a major problem in drug development. It is hard to predict due to its idiosyncratic nature and which does not show up in animal trials. Hepatic adaptive stress response pathway activation is generally observed in drug-induced liver injury. Dynamical pathway modeling has the potential to foresee adverse effects of drugs before they go in trial. Ordinary differential equation modeling can offer mechanistic insight, and allows us to study the dynamical behavior of stress pathways involved in DILI. Areas covered: This review provides an overview on the progress of the dynamical modeling of stress and death pathways pertinent to DILI, i.e. pathways relevant for oxidative stress, inflammatory stress, DNA damage, unfolded proteins, heat shock and apoptosis. We also discuss the required steps for applying such modeling to the liver. Expert opinion: Despite the strong progress made since the turn of the century, models of stress pathways have only rarely been specifically applied to describe pathway dynamics for DILI. We argue that with minor changes, in some cases only to parameter values, many of these models can be repurposed for application in DILI research. Combining both dynamical models with in vitro testing might offer novel screening methods for the harmful side-effects of drugs.
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Affiliation(s)
- Isoude A Kuijper
- a Division of Toxicology, Leiden Academic Centre for Drug Research , Leiden University , Leiden , The Netherlands
| | - Huan Yang
- a Division of Toxicology, Leiden Academic Centre for Drug Research , Leiden University , Leiden , The Netherlands
| | - Bob Van De Water
- a Division of Toxicology, Leiden Academic Centre for Drug Research , Leiden University , Leiden , The Netherlands
| | - Joost B Beltman
- a Division of Toxicology, Leiden Academic Centre for Drug Research , Leiden University , Leiden , The Netherlands
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de Haan-Rietdijk S, Kuppens P, Hamaker EL. What's in a Day? A Guide to Decomposing the Variance in Intensive Longitudinal Data. Front Psychol 2016; 7:891. [PMID: 27378986 PMCID: PMC4906027 DOI: 10.3389/fpsyg.2016.00891] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [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: 03/18/2016] [Accepted: 05/30/2016] [Indexed: 11/16/2022] Open
Abstract
In recent years there has been a growing interest in the use of intensive longitudinal research designs to study within-person processes. Examples are studies that use experience sampling data and autoregressive modeling to investigate emotion dynamics and between-person differences therein. Such designs often involve multiple measurements per day and multiple days per person, and it is not clear how this nesting of the data should be accounted for: That is, should such data be considered as two-level data (which is common practice at this point), with occasions nested in persons, or as three-level data with beeps nested in days which are nested in persons. We show that a significance test of the day-level variance in an empty three-level model is not reliable when there is autocorrelation. Furthermore, we show that misspecifying the number of levels can lead to spurious or misleading findings, such as inflated variance or autoregression estimates. Throughout the paper we present instructions and R code for the implementation of the proposed models, which includes a novel three-level AR(1) model that estimates moment-to-moment inertia and day-to-day inertia. Based on our simulations we recommend model selection using autoregressive multilevel models in combination with the AIC. We illustrate this method using empirical emotion data from two independent samples, and discuss the implications and the relevance of the existence of a day level for the field.
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Affiliation(s)
- Silvia de Haan-Rietdijk
- Methodology and Statistics, Faculty of Social and Behavioural Sciences, Utrecht University Utrecht, Netherlands
| | - Peter Kuppens
- Department of Psychology, Faculty of Psychology and Educational Sciences, Katholieke Universiteit Leuven Leuven, Belgium
| | - Ellen L Hamaker
- Methodology and Statistics, Faculty of Social and Behavioural Sciences, Utrecht UniversityUtrecht, Netherlands; Department of Psychology, Faculty of Psychology and Educational Sciences, Katholieke Universiteit LeuvenLeuven, Belgium
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De Haan-Rietdijk S, Gottman JM, Bergeman CS, Hamaker EL. Get Over It! A Multilevel Threshold Autoregressive Model for State-Dependent Affect Regulation. Psychometrika 2016; 81:217-41. [PMID: 25091047 PMCID: PMC4764683 DOI: 10.1007/s11336-014-9417-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [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: 10/23/2013] [Indexed: 05/26/2023]
Abstract
Intensive longitudinal data provide rich information, which is best captured when specialized models are used in the analysis. One of these models is the multilevel autoregressive model, which psychologists have applied successfully to study affect regulation as well as alcohol use. A limitation of this model is that the autoregressive parameter is treated as a fixed, trait-like property of a person. We argue that the autoregressive parameter may be state-dependent, for example, if the strength of affect regulation depends on the intensity of affect experienced. To allow such intra-individual variation, we propose a multilevel threshold autoregressive model. Using simulations, we show that this model can be used to detect state-dependent regulation with adequate power and Type I error. The potential of the new modeling approach is illustrated with two empirical applications that extend the basic model to address additional substantive research questions.
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Affiliation(s)
- Silvia De Haan-Rietdijk
- Methodology and Statistics, Faculty of Social and Behavioural Sciences, Utrecht University, P.O. Box 80140, 3508 TC, Utrecht, The Netherlands.
| | | | - Cindy S Bergeman
- Department of Psychology, University of Notre Dame, Notre Dame, IN, USA
| | - Ellen L Hamaker
- Methodology and Statistics, Faculty of Social and Behavioural Sciences, Utrecht University, P.O. Box 80140, 3508 TC, Utrecht, The Netherlands
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Okorokova E, Lebedev M, Lindermann M, Ossadtchi A. Corrigendum: A dynamical model improves reconstruction of handwriting from multichannel electromyographic recordings. Front Neurosci 2016; 9:517. [PMID: 26834543 PMCID: PMC4724721 DOI: 10.3389/fnins.2015.00517] [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] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2015] [Accepted: 12/22/2015] [Indexed: 11/13/2022] Open
Affiliation(s)
- Elizaveta Okorokova
- Centre for Cognition and Decision Making, National Research University Higher School of Economics Moscow, Russia
| | | | - Michael Lindermann
- Department of Biomedical Engineering, Norconnect Inc. Ogdensburg, NY, USA
| | - Alex Ossadtchi
- Centre for Cognition and Decision Making, National Research University Higher School of EconomicsMoscow, Russia; Laboratory of Control of Complex Systems, Institute of Problems of Mechanical Engineering, Russian Academy of SciencesSt. Petersburg, Russia
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Abstract
In this paper, we propose a multilevel process modeling approach to describing individual differences in within-person changes over time. To characterize changes within an individual, repeated measures over time are modeled in terms of three person-specific parameters: a baseline level, intraindividual variation around the baseline, and regulatory mechanisms adjusting toward baseline. Variation due to measurement error is separated from meaningful intraindividual variation. The proposed model allows for the simultaneous analysis of longitudinal measurements of two linked variables (bivariate longitudinal modeling) and captures their relationship via two person-specific parameters. Relationships between explanatory variables and model parameters can be studied in a one-stage analysis, meaning that model parameters and regression coefficients are estimated simultaneously. Mathematical details of the approach, including a description of the core process model-the Ornstein-Uhlenbeck model-are provided. We also describe a user friendly, freely accessible software program that provides a straightforward graphical interface to carry out parameter estimation and inference. The proposed approach is illustrated by analyzing data collected via self-reports on affective states.
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Okorokova E, Lebedev M, Linderman M, Ossadtchi A. A dynamical model improves reconstruction of handwriting from multichannel electromyographic recordings. Front Neurosci 2015; 9:389. [PMID: 26578856 PMCID: PMC4624865 DOI: 10.3389/fnins.2015.00389] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [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: 07/20/2015] [Accepted: 10/05/2015] [Indexed: 11/13/2022] Open
Abstract
In recent years, several assistive devices have been proposed to reconstruct arm and hand movements from electromyographic (EMG) activity. Although simple to implement and potentially useful to augment many functions, such myoelectric devices still need improvement before they become practical. Here we considered the problem of reconstruction of handwriting from multichannel EMG activity. Previously, linear regression methods (e.g., the Wiener filter) have been utilized for this purpose with some success. To improve reconstruction accuracy, we implemented the Kalman filter, which allows to fuse two information sources: the physical characteristics of handwriting and the activity of the leading hand muscles, registered by the EMG. Applying the Kalman filter, we were able to convert eight channels of EMG activity recorded from the forearm and the hand muscles into smooth reconstructions of handwritten traces. The filter operates in a causal manner and acts as a true predictor utilizing the EMGs from the past only, which makes the approach suitable for real-time operations. Our algorithm is appropriate for clinical neuroprosthetic applications and computer peripherals. Moreover, it is applicable to a broader class of tasks where predictive myoelectric control is needed.
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Affiliation(s)
- Elizaveta Okorokova
- Centre for Cognition and Decision Making, National Research University Higher School of Economics Moscow, Russia
| | | | - Michael Linderman
- Department of Biomedical Engineering, Norconnect Inc. Ogdensburg, NY, USA
| | - Alex Ossadtchi
- Centre for Cognition and Decision Making, National Research University Higher School of Economics Moscow, Russia ; Laboratory of Control of Complex Systems, Institute of Problems of Mechanical Engineering, Russian Academy of Sciences St. Petersburg, Russia
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Affiliation(s)
- Thierry Tonon
- Sorbonne Université, UPMC Univ Paris 06, Centre National de la Recherche Scientifique, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff Roscoff, France
| | - Damien Eveillard
- LINA UMR 6241, Centre National de la Recherche Scientifique, EMN, Université de Nantes Nantes, France
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