Stress-Induced Microcracking and Fracture Characterization for Ultra-High-Temperature Ceramic Matrix Composites at High Temperatures

In this paper, we estimated the temperature-dependent critical inclusion size for microcracking under residual stress and applied stress for particulate-reinforced ultra-high-temperature ceramic matrix composites. The critical flaw size and applied stress for the stable growth of radial cracks under different temperatures were also estimated. It was found that under a lower applied stress, the critical inclusion size was sensitive to the temperature. Under higher applied stresses, the sensitivity became smaller. For ceramic materials with pre-existing microcracks, the crack resistance could be improved by increasing the service stress when the service stress was low. As the temperature increased, the critical flaw size of the materials decreased; the applied stress first increased and then decreased. Finally, a temperature-dependent fracture strength model of composites with a pre-existing critical flaw was proposed. A good agreement was obtained between the model prediction and the experimental data. In this work, we show a method for the characterization of the effects of temperature on the fracture behavior of ceramic-based composites.

Theoretical Modeling Method for Material Removal Characteristics of Abrasive Water Jet Polishing under Rotating Oblique Incidence

Abrasive water jet polishing (AWJP), as an ultra-precision machining technology, has unique machining advantages. However, the machining application of nozzles in vertical and inclined states is greatly limited because rotational symmetric material removal characteristics and the largest amount of central material removal cannot be obtained. At the same time, considering the many controllable and uncontrollable factors in AWJP, it is difficult to accurately model the removal characteristics obtained by machining. Based on the idea of the Preston equation and the calculation of fluid dynamics, this study first analyzed the material removal characteristics of a single abrasive particle and used FLUENT fluid simulation software to obtain the pressure and velocity distributions at different positions in the processes of nozzle rotation and tilt polishing. By analyzing the influence of the pressure and velocity distributions on material removal and the surface shear stress of the workpiece, a theoretical model of the material removal characteristics of abrasive water jet polishing under rotating oblique incidence was established. Finally, the effectiveness of the theoretical removal model was verified by comparing and analyzing experimental and theoretical results.

Thermally driven single-electron stochastic resonance

Stochastic resonance (SR) in a single-electron system is expected to allow information to be correctly carried and processed by single electrons in the presence of thermal fluctuations. Here, we comprehensively study thermally driven single-electron SR. The response of the system to a weak voltage signal is formulated by considering the single-electron tunneling rate, instead of the Kramers' rate generally used in conventional SR models. The model indicates that the response of the system is maximized at finite temperature and that the peak position is determined by the charging energy. This model quantitatively reproduces the results of a single-electron device simulator. Single-electron SR is also demonstrated using a GaAs-based single-electron system that integrates a quantum dot and a high-sensitivity charge detector. The developed model will contribute to our understanding of single-electron SR and will facilitate accurate prediction, design, and control of single-electron systems.

Relationships Among Environmental Variables, Physical Capacity, Balance Self-Efficacy, and Real-World Walking Activity Post-Stroke

BACKGROUND

Social and physical environmental factors affect real-world walking activity in individuals with stroke. However, environmental factors are often non-modifiable, presenting a challenge for clinicians working with individuals with stroke whose real-world walking is limited due to environmental barriers.

OBJECTIVE

The purpose of this work was to test a model hypothesizing the relationships among environmental factors (specifically, living situation and area deprivation), modifiable factors, and real-world walking activity to understand opportunities for intervention. We hypothesized that balance self-efficacy would mediate the relationship between the environment and real-world walking and that physical capacity would moderate this mediation.

METHODS

This was a cross-sectional study of 282 individuals with chronic (≥6 months) stroke. We tested the indirect effect to determine if mediation was present. Multiple group structural equation modeling was used to test if physical capacity moderated this mediation. A χ² difference test was used to compare the moderation model against the null (no moderation) model.

RESULTS

Balance self-efficacy mediated the relationship between area deprivation and real-world walking (indirect effect: β = -0.04, P = .04). Both the moderation and null models fit the data equally well statistically (χ²(5) = 6.9, P = .23). We therefore accepted the simpler (null) model and concluded that the mediation was not moderated.

CONCLUSIONS

Targeting balance self-efficacy may be an effective approach to improving real-world walking in persons with stroke who experience barriers within the physical environment. A stroke survivor's physical capacity may not impact this approach. Future work should consider utilizing more specific measures of the social and physical environment to better understand their influences on real-world walking activity in individuals with stroke. However, the results of this work provide excellent targets for future longitudinal studies targeting real-world walking activity in stroke.

Monitoring COVID-19 in Colombia during the first year of the pandemic

Background:

COVID-19 cases in Medellín, the second largest city in Colombia, were monitored during the first year of the pandemic using both mathematical models based on transmission theory and surveillance from each observed epidemic phase.

Design and Methods:

Expected cases were estimated using mandatory reporting data from Colombia’s national epidemiological surveillance system from March 7, 2020 to March 7, 2021. Initially, the range of daily expected cases was estimated using a Borel-Tanner stochastic model and a deterministic Susceptible-Infected-Removed (SIR) model. A subsequent expanded version of the SIR model was used to include asymptomatic cases, severe cases and deaths. The moving average, standard deviation, and goodness of fit of estimated cases relative to confirmed reported cases were assessed, and local transmission in Medellin was contrasted with national transmission in Colombia.

Results:

The initial phase was characterized by imported case detection and the later phase by community transmission and increases in case magnitude and severity. In the initial phase, a maximum range of expected cases was obtained based on the stochastic model, which even accounted for the reduction of new imported cases following the closure of international airports. The deterministic estimate achieved an adequate fit with respect to accumulated cases until the conclusion of the mandatory national quarantine and gradual reopening, when reported cases increased. The estimated new cases were reasonably fit with the maximum reported incidence.

Conclusion:

Adequate model fit was obtained with the reported data. This experience of monitoring epidemic trajectory can be extended using models adapted to local conditions.

Patient and public involvement in oesophageal cancer survivorship research

BACKGROUND

Good clinical research is often conducted in close collaboration between patients, the public, and researchers. Few studies have reported the development of patient and public involvement (PPI) in research outside the United States and the United Kingdom, and for patients with more aggressive cancers. The study aimed to describe and evaluate the development of PPI in oesophageal cancer survivorship research in Sweden by the use of a framework to support the process.

METHODS

Oesophageal cancer survivors were recruited to a PPI research collaboration at Karolinska Institutet, Sweden. The development process was supported by the use of a framework for PPI, 'Patient and service user engagement in research'. Insights, benefits, and challenges of the process were described and discussed among the collaborators.

RESULTS

The collaboration resulted in joint publications with a more patient- and family-focussed perspective. It also contributed to the development of information folders about survivorship after oesophageal cancer surgery and national conference arrangements for patients, their families, healthcare workers, and researchers. Since the PPI contributors were represented in patient organisations and care programmes, the dissemination of research results increased. Their contributions were highly valued by the researchers, but also revealed some challenges. The use of a structured framework contributed to support and facilitated the process of establishing PPI in research collaboration.

CONCLUSIONS

A genuine interest in establishing PPI in research and an understanding and respect for the patients' expertise in providing a unique inside perspective was imperative for a successful collaboration. Research focus should not only be on mortality and reductions in daily life, but also on positive outcomes. Using a framework supports development and avoids pitfalls of PPI collaboration.

PATIENT AND PUBLIC CONTRIBUTION

Patient partners were equal collaborators in all aspects of the study.

Enhancement of Aging in Place: An Evolving Understanding of Person-Centered Dementia Care in Home Settings

BACKGROUND

There has been a rich body of literature on informal caregivers of persons with dementia (PWD). However, little has been discussed on how to facilitate person-centered dementia care in home settings with spouses as primary caregivers. We tend to take it for granted that spouses provide person-centered care for PWD. However, being spouses of PWD and living with them for several decades does not necessarily mean that it is easier for them to provide person-centered dementia care and maintain valued and healthy relationships.

OBJECTIVE

The current study aimed to explore dyadic experiences of PWD and their spousal caregivers and develop a culturally and contextually-sensitive understanding of person-centered dementia care in home-based settings.

METHODS

A total of 20 dyads of PWD and their care partners were selected for this study. A trained qualitative interviewer conducted a one-on-one interview with each participant with dementia and their care partners separately. We adopted both conventional and directed content analyses.

RESULTS

Our findings provide examples of care partners provide person-centered care, resulting in a profound positive impact on their wellbeing. Adaptive leadership and collaborative work emerged as a key finding in facilitating person-centered dementia care. Cultural relevancy of person-centered dementia care was also interpreted from the data. The study findings provide implications for the evolving of person-centered dementia care model in home-based settings.

CONCLUSION

Findings from this study highlight the significance of facilitating person-centered dementia care in home-based settings between PWD and their primary family caregivers.

The relationship between the manifestations of mobbing and reactions of mobbing victims

BACKGROUND

The study concerned workplace mobbing, a phenomenon affecting about 3-20% of the Polish population. The aim of the article is to distinguish the manifestations of mobbing, to study the coexistence of mobbing manifestations, and to search for the relationships between the symptoms of mobbing, reactions to mobbing and methods of dealing with mobbing used by victims.

MATERIAL AND METHODS

Information on the above variables was obtained using a questionnaire on mobbing, risk factors, and responses to mobbing. The questionnaire was completed by 781 people (women: 66%, men: 34%). The average age of the respondents was 29 years. The current statistical analysis included: distinguishing the manifestations of mobbing by means of a confirmatory factor analysis, studying the coexistence of mobbing manifestations by means of a cluster analysis, and detecting the relationships between mobbing manifestations, reactions to mobbing and ways of dealing with it based on the system of structural equations.

RESULTS

The results of the research revealed 3 categories of relationships: a co-occurrence of mobbing manifestations, a relationship of mobbing manifestations with reactions to mobbing, and a relationship of mobbing reactions with methods of dealing with mobbing.

CONCLUSIONS

Mobbing was found in 22% of the examined group. The study revealed the existence of 5 clusters of mobbing manifestations (i.e., subgroups of respondents characterized by experiencing at least 1 of the mobbing manifestations). In the most numerous clusters in which the symptoms of mobbing were diagnosed, unfriendly working conditions prevailed. In the context of mobbing, people were found to more often react with passivity or with using interpersonal coping methods. However, they rarely turned to institutions for help or used aggression against the mobber. Med Pr. 2022;73(1).

Theoretical and Experimental Investigation on the 3D Surface Roughness of Material Extrusion Additive Manufacturing Products

Material extrusion (ME), one of the most widely used additive manufacturing technique, has the advantages of freedom of design, wide range of raw materials, strong ability to manufacture complex products, etc. However, ME products have obvious surface defects due to the layer-by-layer manufacturing characteristics. To reveal the generation mechanism, the three-dimensional surface roughness (3DSR) of ME products was investigated theoretically and experimentally. Based on the forming process of bonding neck, the 3DSR theoretical model in two different directions (vertical and parallel to the fiber direction) was established respectively. The preparation of ME samples was then completed and a series of experimental tests were performed to determine their surface roughness with the laser microscope. Through the comparison between theoretical and experimental results, the proposed model was validated. In addition, sensitivity analysis is implemented onto the proposed model, investigating how layer thickness, extrusion temperature, and extrusion width influence the samples' surface roughness. This study provides theoretical basis and technical insight into improving the surface quality of ME products.

Theoretical model and measurement of shared decision making in web-based pharmaceutical care consultation

Objectives

We aimed to construct a theoretical model and an observer-based measurement of shared decision making (SDM) in web-based pharmaceutical care consultation.

Methods

We first constructed a theoretical model through analysis of SDM models and interviews with 24 key informants. Then, the initial measurement was formulated, and the content was evaluated by 16 key informants alone. A cross-sectional study was executed, where 300 provider-patient encounters were collected at the online platform ‘Good Doctor Website’, for reliability and validity assessment. Content validity was evaluated by appropriateness score, that is the median of 7–9 and without disagreement. Interrater reliability was evaluated by Spearman correlation coefficient using 30 out of 300 samples. Single indicator validity was tested by Pearson correlation analysis, and convergent validity was evaluated by the Multiple Indicators Multiple Causes (MIMIC) model using 300 samples.

Results

Theoretical model constructed included four elements: ‘comprehensive understanding of the patient's condition’, ‘exchanging ideas on medication options’, ‘achieving a medication plan’, and ‘providing decision support’. Measurement constructed included four dimensions and 19 items, and four dimensions were in accordance with four elements of the theoretical model. We found median scores of these dimensions and items were 7–9 and without disagreement, indicating good content validity. Spearman correlation coefficients of 19 items were greater than 0.750, suggesting good interrater reliability. Pearson coefficients between 19 items and their external variables were significant (p < 0.001), and MIMIC model results showed that the R² values of dimensions 1–4 were over 0.5, indicating good single indicator validity and convergent validity.

Conclusions

Characteristics of web-based pharmaceutical care consultation, highlighting the importance of medication history, medication regimen, and detailed medication plan, were observed in the theoretical model. Measurement constructed had good reliability and validity and may be used by health policymakers to improve the quality of pharmaceutical care consultation online.

Development and Proof-of-Concept Evaluation of a Sensory Science-Based Model for Product Development of Vegetable-Based Products for Children

Children's vegetable intake is too low, and a key barrier to the inadequate intake is low acceptance. To facilitate successful development of new vegetable-based products for children, a sensory science approach to product development has been taken. A new theoretical model is proposed, the CAMPOV model: Children's Acceptance Model for Product development of Vegetables. The model is informed by scientific literature and considers biological, psychological, and situational, and intrinsic and extrinsic product factors relevant to children's acceptance of vegetables, with a focus on modifiable factors at the product level. Simultaneously, 14 new vegetable-based product concepts for children were developed and evaluated through focus groups with 5-8-year-olds (n = 36) as a proof-of-concept evaluation of the model. Children had high interest in six of the concepts. Factors identified from the literature that positively associated with the children's interest in the concepts included bright colours, bite-sized pieces, good taste, fun eating experience, and familiarity. The CAMPOV model and proof-of-concept evaluation results can guide further sensory and consumer research to increase children's acceptance of food products containing vegetables, which will in turn provide further insights into the validity of the model. The food industry can use the model as a framework for development of new products for children with high sensory appeal.

Study on Mechanical Characteristics of Segmental Joints of a Large-Diameter Shield Tunnel under Ultrahigh Water Pressure

At present, there is no clear design standard for segmental joints of large-diameter shield tunnels under high water pressure. In this paper, a theoretical calculation model for the bending stiffness of segmental joints under high water pressure is proposed. The numerical simulation method is used to investigate the failure and crack formation processes of single-layer and double-layer lining segments under large axial forces. The effects of axial force, bolt strength, and concrete strength on the bending stiffness of joints are then studied using a theoretical calculation model of segmental joints. The results show that under extremely high water pressure, the influence of double lining on joint stiffness is limited. It is more rational and safe to compute the bending stiffness of segmental joints using this theoretical model rather than the numerical simulation method. The parameter analysis reveals that increasing the bolt strength has a minor impact on bending stiffness and deformation, whereas increasing the concrete strength has the opposite effect. The influence of ultimate bearing capacity and deformation decreases non-linearly as the axial force increases.

Determinants of Intention to Use Artificial Intelligence-Based Diagnosis Support System Among Prospective Physicians

Background: This study aimed to develop a theoretical model to explore the behavioral intentions of medical students to adopt an AI-based Diagnosis Support System.

Methods: This online cross-sectional survey used the unified theory of user acceptance of technology (UTAUT) to examine the intentions to use an AI-based Diagnosis Support System in 211 undergraduate medical students in Vietnam. Partial least squares (PLS) structural equational modeling was employed to assess the relationship between latent constructs.

Results: Effort expectancy (β = 0.201, p < 0.05) and social influence (β = 0.574, p < 0.05) were positively associated with initial trust, while no association was found between performance expectancy and initial trust (p > 0.05). Only social influence (β = 0.527, p < 0.05) was positively related to the behavioral intention.

Conclusions: This study highlights positive behavioral intentions in using an AI-based diagnosis support system among prospective Vietnamese physicians, as well as the effect of social influence on this choice. The development of AI-based competent curricula should be considered when reforming medical education in Vietnam.

Olfactory landmarks and path integration converge to form a cognitive spatial map

The convergence of internal path integration and external sensory landmarks generates a cognitive spatial map in the hippocampus. We studied how localized odor cues are recognized as landmarks by recording the activity of neurons in CA1 during a virtual navigation task. We found that odor cues enriched place cell representations, dramatically improving navigation. Presentation of the same odor at different locations generated distinct place cell representations. An odor cue at a proximal location enhanced the local place cell density and also led to the formation of place cells beyond the cue. This resulted in the recognition of a second, more distal odor cue as a distinct landmark, suggesting an iterative mechanism for extending spatial representations into unknown territory. Our results establish that odors can serve as landmarks, motivating a model in which path integration and odor landmarks interact sequentially and iteratively to generate cognitive spatial maps over long distances.

Model of Social Support for Patients Treated for Cancer

Social support can be one of the main factors in better assessing the quality of life at any stage of the recovery process. It should meet the patient's needs so that they can develop constructive methods of coping with the disease. In order to explain the factors influencing social support for cancer patients, a theoretical research model was formulated. It is presented in a graphic form in this article. In order to verify the model, the authors' questionnaire and other standardised questionnaires were used. The experimental group consisted of 170 hospitalised oncological patients being treated for cancer. Personality structure, through its relationship with state of health (0.40) and attitude developed to the disease (0.64), influenced the support experienced by the treated patients (0.40). The surveyed patients, who were characterised by positive self-esteem and experience of life satisfaction despite various difficult situations, perceived to a greater degree the emotional and instrumental support provided to them. During cancer treatment, those patients who showed a need for help and did not experience negative emotions were characterised by an increased need for support. The research results can be introduced into evidence-based medical practice, which could significantly improve the quality of nursing and medical care for patients.

Government Epidemic Prevention and Economic Growth Path Under Public Health Emergency: Theoretical Model and Simulation Analysis

This paper constructs a partial equilibrium model under public health emergency shocks based on economic growth theory, and investigates the relationship between government intervention and virus transmission and economic growth path. We found that both close contacts tracing measures and isolation measures are beneficial to human capital stock and economic output per capita, and the effect of close contact tracing measures is better than that of isolation measures. For infectious diseases of different intensities, economic growth pathways differed across interventions. For low contagious public health emergencies, the focus should be on the coordination of isolation and tracing measures. For highly contagious public health emergencies, strict isolation, and tracing measures have limited effect in repairing the negative economic impact of the outbreak. The theoretical model provides a basic paradigm for the future researches to study economic growth under health emergencies, with good scalability and robustness.

[Behavioral imaging of serum albumin during matrine transport based on capillary electrophoresis]

Matrine (MT) is an alkaloid widely used in the treatment of tumor diseases. It is the main medicinal ingredient in the dried roots of kuh-seng (Sophora flavescens Ait). However, there have been few studies on its transport mechanism. Serum albumin (SA) is the most abundant protein in blood. SA combines easily with many substances, including MT. MT and human serum albumin (HSA) were analyzed by capillary electrophoresis (CE) under in vitro conditions. The capillary tubing was 50 μm. The total length of the capillary was 60 cm, the total effective length was 50 cm. The interaction models of ligand-receptor binding were constructed by the mobility and frontal analysis (FA) methods. The purpose of establishing the interaction model was to study the binding of MT and SA. The phosphate buffer solution (PBS, 0.02 mol/L) was prepared in double distilled water. All solutions were prepared in PBS (0.02 mol/L). All solutions were filtered twice through a 0.45 μm microporous membrane, degassed for 5 min at a time. In the mobility method, different gradient MT solutions were used as running buffers. Their concentrations were 1.0×10^-4-1.0×10^-3 mol/L, with the gradient of 1.0×10^-4 mol/L. And the HSA solution containing (0.5% (v/v)) acetone was used as test sample. Its concentration was 1.0×10^-5 mol/L. The nonlinear fitting method was used to obtain the binding parameters of MT and HSA. In the FA method, different gradient MT-HSA solutions were used as test samples. Their concentrations were 1.0×10^-4-1.0×10^-3 mol/L, with the gradient of 1.0×10^-4 mol/L. And the PBS solution (0.02 mol/L) was used as running buffer. Then three equations were used to obtain the binding parameters of MT and HSA. And the applicability of the models was analyzed using the binding parameters. These three equations were nonlinear regression equation, Scatchard linear equation, and Klotz linear equation. Using the mobility method, the apparent binding constant K_B was 8.072×10³ mol/L. According to the FA method, three apparent binding constants were obtained for MT and HSA. The apparent binding constant K_B of HSA and MT by nonlinear regression equation, Scatchard linear equation and Klotz linear equation were 1.434×10³, 1.781×10³ and 2.133×10³ mol/L. The comparison was as follows, K_{B(nonlinear regression equation)} < K_{B(Scatchard linear equation)} < K_{B(Klotz linear equation)}. The number of binding sites was about 1.0. It was indicating that MT had only a single type of binding site with HSA. By analyzing the applicability of the model, the correlation coefficients (r) of the three equations were obtained. The comparison was as follows, r_{(Klotz linear equations)} > r_{(nonlinear regression equations)} > r_{(Scatchard linear equations)}. The results showed that both the methods were all suitable for analyzing the MT-SA system. The FA method could calculate the apparent binding constants and the numbers of binding sites. Therefore, it was more suitable for the analysis of MT and HSA. And the Klotz linear equation was the best fit for the theoretical model among the three equations. The combined parameters indicated that the interaction of MT with HSA had only one binding site. And the binding of MT with HSA was stable. This experimental method could be used to determine the binding status of MT and HSA. It is useful to further explore the binding mechanism of MT and HSA. This work provides valuable information on the interaction mechanism of typical alkaloids with SA. It will be useful in studies of the blood transport mechanisms of alkaloids.

Health and Risk Behaviors of Bystanders: An Integrative Theoretical Model of Bystanders' Reactions to Mistreatment

This article constructs a comprehensive theoretical model that outlines bystanders' emotional and behavioral responses to the mistreatment of adolescent peers. The model captures bystanders' risk and health risk behaviors, which have been overlooked in the context of their reactions; when addressed at all in connection with bystanders of bullying among adolescents, they have been treated separately. Here, we present bystanders' emotional and cognitive reactions and their impact on bystanders' responses including a set of responses that demonstrate risk and health risk behaviors that are directed to the bystander as a victim by proxy. The theoretical framework is the conservation of resources theory, which posits that personal resources (i.e., potency and moral disengagement) and social resources impact the process that leads to bystanders' reactions. Previous models have overlooked the integrative viewpoint of bystanders, and comprehensive models that explain bystanders' behavioral and emotional responses have received little attention especially with regards to adolescents. Two recent models overlooked core features embedded in the current model, including the risk and health risk behaviors that it integrates. The proposed model presents a novel and more comprehensive view of bystanders' reactions and the process underlying these reactions. It integrates existing knowledge embedded in other existing models. At the same time, this perspective indicates the centricity of potency as a key resource that dictates the emotional response and behaviors of bystanders. This potentially allows for new applications in the mitigation of adverse impacts that follow the witnessing of mistreatment. The article discusses these applications, which are based on previous findings, their implications for practice, and directions for future empirical research necessary to validate the model.

Distinct roles of red-blood-cell-derived and wall-derived mechanisms in metabolic regulation of blood flow

OBJECTIVE

A theoretical model is used to analyze combinations of RBC-derived and wall-derived (RBC-independent) mechanisms for metabolic blood flow regulation, with regard to their oxygen transport properties.

METHODS

Heterogeneous microvascular network structures are derived from observations in rat mesentery and hamster cremaster. The effectiveness of metabolic blood flow regulation using combinations of RBC-dependent and RBC-independent mechanisms is simulated in these networks under conditions of reduced oxygen delivery and increased oxygen demand.

RESULTS

Metabolic regulation by a wall-derived mechanism results in higher predicted total blood flow rate and number of flowing vessels, and lower tissue hypoxic fraction, than regulation by combinations of RBC-derived and wall-derived signals. However, a combination of RBC-derived and wall-derived signals results in a higher predicted median tissue P_O2 than either mechanism acting alone.

CONCLUSIONS

Model results suggest complementary roles for RBC-derived and wall-derived mechanisms of metabolic flow regulation, with the wall-derived mechanism responsible for avoiding hypoxia, and the RBC-derived mechanism responsible for maintaining P_O2 levels high enough for optimal tissue function.

Is mitochondrial reactive oxygen species production proportional to oxygen consumption? A theoretical consideration

It has been assumed that at the whole organismal level, the mitochondrial reactive oxygen species (ROS) production is proportional to the oxygen consumption. Recently, a number of researchers have challenged this assumption, based on the observation that the ROS production per unit oxygen consumed in the resting state of mitochondrial respiration is much higher than that in the active state. Here, we develop a simple model to investigate the validity of the assumption and the challenge of it. The model highlights the significance of the time budget that mitochondria operate in the different respiration states. The model suggests that under three physiologically possible conditions, the difference in ROS production per unit oxygen consumed between the respiration states does not upset the proportionality between the whole animal ROS production and oxygen consumption. The model also shows that mitochondrial uncoupling generally enhances the proportionality.

Cause or Effect? The Role of Prognostic Uncertainty in the Fear of Cancer Recurrence

Background

Fear of cancer recurrence (FCR) is an important cause of suffering for cancer survivors, and both empirical evidence and theoretical models suggest that prognostic uncertainty plays a causal role in its development. However, the relationship between prognostic uncertainty and FCR is incompletely understood.

Objective

To explore the relationship between prognostic uncertainty and FCR among patients with ovarian cancer (OC).

Design

A qualitative study was conducted utilizing individual in-depth interviews with a convenience sample of patients with epithelial ovarian cancer who had completed first-line treatment with surgery and/or chemotherapy. Semi-structured interviews explored participants’ (1) understanding of their prognosis; (2) experiences, preferences, and attitudes regarding prognostic information; and (3) strategies for coping with prognostic uncertainty. Inductive qualitative analysis and line-by-line software-assisted coding of interview transcripts was conducted to identify key themes and generate theoretical insights on the relationship between prognostic uncertainty and FCR.

Results

The study sample consisted of 21 participants, nearly all of whom reported experiencing significant FCR, which they traced to an awareness of the possibility of a bad outcome. Some participants valued and pursued prognostic information as a means of coping with this awareness, suggesting that prognostic uncertainty causes FCR. However, most participants acknowledged fundamental limits to both the certainty and value of prognostic information, and engaged in various strategies aimed not at reducing but constructing and maintaining prognostic uncertainty as a means of sustaining hope in the possibility of a good outcome. Participants’ comments suggested that prognostic uncertainty, fear, and hope are connected by complex, bi-directional causal pathways mediated by processes that allow patients to cope with, construct, and maintain their uncertainty. A provisional dual-process theoretical model was developed to capture these pathways.

Conclusion

Among patients with OC, prognostic uncertainty is both a cause and an effect of FCR—a fear-inducing stimulus and a hope-sustaining response constructed and maintained through various strategies. More work is needed to elucidate the relationships between prognostic uncertainty, fear, and hope, to validate and refine our theoretical model, and to develop interventions to help patients with OC and other serious illnesses to achieve an optimal balance between these states.

Experimental Investigation and Modeling of Damage Accumulation of EN-AW 2024 Aluminum Alloy under Creep Condition at Elevated Temperature

The paper is focused on creep-rupture tests of samples made of the 2024 alloy in the T3511 temper under uniaxial tensile stress conditions. The basic characteristics of the material at the temperatures of 100, 200 and 300 °C were determined, such as the Young’s modulus E, yield point σ_y, ultimate tensile strength σ_c and parameters K and n of the Ramberg–Osgood equation. Creep tests were performed for several different levels of nominal axial stress (load) at each temperature. It was observed that in the process of creep to failure at 200 and 300 °C, as the stress decreases, the creep time increases and, at the same time, the strain at rupture increases. However, such a regularity is maintained until a certain transition stress value σ_t is reached. Reducing the stress below this value results in a decreased value of the strain at rupture. A simple model of creep damage accumulation was proposed for the stress range above the transient value. In this model, the increase in the isotropic damage state variable was made dependent on the value of axial stress and the increase in plastic axial strain. Using the results of experimental creep-rupture tests and the failure condition, the parameters of the proposed model were determined. The surface of fractures obtained in the creep tests with the use of SEM technology was also analyzed.

Fiber-Based Gas Filter Assembled via In Situ Synthesis of ZIF-8 Metal Organic Frameworks for an Optimal Adsorption of SO2: Experimental and Theoretical Approaches

For environmental protection from exposure to airborne toxic gases, metal organic frameworks (MOFs) have drawn great attention as gas adsorbent options, with their advantages in chemical tailorability and large porosity. To develop a fiber-based gas filter that is effective against SO₂ gas, zeolite imidazole framework-8 (ZIF-8) was applied to polypropylene nonwoven by various methods. Among the tested methods, the sol-gel impregnation method showed the highest ZIF-8 loading efficiency. There existed an optimal loading of ZIF-8 for the maximum adsorption efficiency, and it was associated with the accessibility of gas molecules to the ZIF-8 pores and active sites. Dominant adsorption processes and mechanisms were investigated by fitting the theoretical sorption models to experimental data. The results demonstrate that the increased ZIF-8 loading to fibers, beyond a certain level, may hinder the diffusivity and increase the barrier effect, eventually decreasing the adsorption efficiency. This study is novel and significant in that a multifaceted approach, including experimental analysis, theoretical investigation, and computational modeling, was made for scrutinizing the intricate phenomena occurring in the gas sorption process. The results of this study provide the fundamental yet practical information on the manufacturing considerations for the optimal design of MOF-loaded fibrous adsorbents.

From Topological Analyses to Functional Modeling: The Case of Hippocampus

Topological data analyses are widely used for describing and conceptualizing large volumes of neurobiological data, e.g., for quantifying spiking outputs of large neuronal ensembles and thus understanding the functions of the corresponding networks. Below we discuss an approach in which convergent topological analyses produce insights into how information may be processed in mammalian hippocampus—a brain part that plays a key role in learning and memory. The resulting functional model provides a unifying framework for integrating spiking data at different timescales and following the course of spatial learning at different levels of spatiotemporal granularity. This approach allows accounting for contributions from various physiological phenomena into spatial cognition—the neuronal spiking statistics, the effects of spiking synchronization by different brain waves, the roles played by synaptic efficacies and so forth. In particular, it is possible to demonstrate that networks with plastic and transient synaptic architectures can encode stable cognitive maps, revealing the characteristic timescales of memory processing.

An Integrated Model of Nature and Nurture Factors that Contribute to Addiction and Recovery

BACKGROUND

In the context of the opioid epidemic and growing awareness of addiction as a public health concern, there are efforts to inform the public, patients, families, and policy makers about the factors that contribute to addiction and facilitate recovery. Several theoretical models provide useful frameworks for this discussion, but each of them has limitations.

OBJECTIVES

This paper presents an accessible yet comprehensive theoretical model that integrates empirical evidence about addiction etiology and recovery using the nature-nurture paradigm.

RESULTS

The model presents substance use along a continuum, and identifies risk and protective factors in multiple domains that have been identified by research. The domains on the nature side of the model include genetic and biological factors, comorbid psychiatric and medical disorders, physiological reinforcement of substance use, and changes to neural mechanisms. The domains on the nurture side of the model include sociocultural factors, environmental factors, personality, emotions, cognitions, psychological reinforcement of substance use, and cognitive and behavioral changes. The progression from increased or decreased substance use to addiction or recovery is mediated by changes in neural mechanisms and cognitive and behavioral changes, which have feedback loops with the physiological and psychological reinforcement.Conclusions/Importance: This model is a useful heuristic, consistent with a public health framework, for discussing addiction and recovery with patients, their families, and the public. This integrated model of nature and nurture factors has the potential to inform clinical practice, consultation, research, prevention programs, educational programs, and public policy.