Multi-group Model Research Articles

Unraveling the longitudinal reciprocal associations between anxiety, delinquency, and depression from early to middle adolescence

Research that simultaneously tests developmental associations between anxiety, depression, and delinquency is limited. The current study was designed to test the hypothesis that anxiety would inhibit involvement in delinquency, whilst involvement in delinquency would be a risk factor for later depression. During middle school, a large sample of Greek Cypriot adolescents completed measures of anxiety, depression, and delinquency across four waves (N = 1451 in wave 1: 50.1% girls, Mage = 12.12, SD = 0.55; N = 1224 in wave 4). Analyses of longitudinal data supported the study's hypotheses after controlling for the common variance among the variables at each point of measurement. Altogether, the current results showcase that anxiety and depression are inversely related to delinquency, in that depression positively predicted later delinquency, whereas anxiety negatively predicted delinquent behaviors. Further, delinquency was a risk factor for future depression, but not anxiety, pointing to a bidirectional association between delinquency and depression. A multi-group path model showed that findings held across sex, with one exception, being that the relation between delinquency and depression during early adolescence was only significant for girls. The present study demonstrates that future research must consider uni- and bi-directional effects when disentangling longitudinal associations between anxiety, depression, and delinquency.

The time eigenvalue spectrum for nuclear reactors in multi-group diffusion theory

We develop a fully analytical study of the spectrum of the neutron diffusion operator both for spatially homogeneous and reflected reactors in a multi-group energy model. We illustrate and discuss the results of the analysis of the time spectrum of the diffusion operator, to highlight some general properties of the neutronic evolution in a multiplying system. Various new results are presented, particularly regarding the possible existence of complex time eigenvalues, the appearance of a continuum part of the spectrum and the orthogonality properties of the eigenfunctions in the case of an infinite reflector.

A multigroup SEIR epidemic model with age‐dependent latency and relapse

Different multigroup epidemic models have been proposed, but few models include the latent class that becomes infectious at different rates and the fact that the removed class may relapse into an infectious class at different rates. In this paper, a multigroup SEIR epidemic model is constructed to study the transmission dynamics of infectious diseases with age‐dependent latency and relapse. The model is realistic for some infectious diseases, such as TB and herpes virus. The sharp threshold condition, which corresponds to the well‐known basic reproduction number , is derived, and it determines the global stability of each equilibrium. In particular, if , then the disease‐free equilibrium is globally asymptotically stable, whereas if , the endemic equilibrium exists uniquely and is globally asymptotically stable. We utilize appropriate Lyapunov functionals, graph‐theoretical results, and the LaSalle's invariance principle to prove these results. Two specific examples and their corresponding numerical simulations are provided to explain the obtained results.

Wolbachia's role in mediating its flea's reproductive success differs according to flea origin.

Endosymbionts-microbes that live within and engage in prolonged and intimate associations with their hosts-are gaining recognition for their direct impact on plant and animal reproduction. Here we used the overlooked Wolbachia-flea system to explore the possibility that endosymbionts may also play a role as mediators in shaping the reproductive success of their hosts. We simultaneously quantified the Wolbachia density in field- and laboratory-originated fleas that fed and mated on rodents for either 5 or 10 days and assessed their body size and current reproductive success. By combining multigroup analysis and model selection approaches, we teased apart the contribution of the direct effects of the flea's physiological age and body size and the mediation effect of its Wolbachia endosymbionts on flea reproductive success, and we showed that the latter was stronger than the former. However, interestingly, the mediation effect was manifested only in laboratory-originated fleas, for which the increase in Wolbachia with age translated into lower reproductive success. These results suggest that some well-supported phenomena, such as aging effects, may be driven by endosymbionts and show once again that the role of endosymbionts in shaping the reproductive success of their host depends on their selective environment.

Exploration of Raman exfoliated cytology for oral and cervical cancers

Exfoliated cell are one of the most patient compliant specimens, hence are workhorse of successful screening programs in cancers like cervix. Raman exfoliative cytology (REC), even on cell pellets using Raman microprobe, has demonstrated ∼80% specificity, comparable to conventional screening programs. Objective of this study is to further evaluate Raman spectroscopy, which is sensitive to biochemical composition, vis-a-vis conventional morphology based cytology that differentiates cell-type but not the origin. Exploration of this kind further corroborates utility and efficacy of REC as screening tool, also can pave way to prospective multi-cancer screening by a multi-group model. Therefore, the present study explores REC in a stringent two-cancer, four-group model for classification of 44 oral [29, tumor (OT), 15 normal (ON)] and 66 cervical (38 tumor (CT), 28 normal (CN)] exfoliated cell specimens. Spectra were acquired from cell pellets using Raman microprobe. Spectra were analyzed in two approaches, spectra-wise and subject-wise to circumvent inherent heterogeneity due to co-localization of normal cells in malignant specimens. In the first approach, PCA and LDA yielded a classification efficiency of 82% for OT and 77% for CT. A slightly higher classification (OT, 86% and CT, 84%) was achieved for the subject-wise approach. Thus findings of this study demonstrate similar efficacy and specificity to that of individual cancer-based models reported earlier. These findings are quite encouraging especially for resource deprived and under privileged countries where these two cancers are more prevalent and could be useful for prospective centralized REC facility.

Global stability for a multi-group SVIR model with age of vaccination

In this paper, a multi-group SVIR epidemic model with age of vaccination is considered. The model allows the vaccinated individuals to become susceptible after the vaccine loses its protective properties, and the vaccination classes satisfy first-order the partial differential equations structured by vaccination age. Combining the Lyapunov functional method with a graph-theoretic approach, we show that the global stability of endemic equilibrium for the strongly connected system is determined by the basic reproduction number. In addition, the dynamics for non-strongly connected model are also investigated, depending on the basic reproduction numbers corresponding to each strongly connected component. Numerical simulations are carried out to support the theoretical conclusions.

A mediated multigroup model examining marijuana use consequences by sexual orientation in us college students

Marijuana use holds a curvilinear relation to sexual orientation, whereby bisexual individuals reporter higher frequency of use than exclusively hetero- or homosexual individuals. This relation differs by gender, with more pronounced differences among women. Bisexual individuals are at greater risk for negative consequences of marijuana use, such as dependence. To mitigate potential risks, individuals employ protective behavioral strategies (PBS). While differences in use are known, research has yet to examine if consequences and PBS use vary by sexual orientation. This study seeks to address the relations between sexual orientation, consequences, gender, and PBS. It was hypothesized that orientation would be associated with consequences, mediated by PBS, and these relations would vary by gender. College students (N = 8141) from 11 different universities completed an online survey measuring marijuana consequences, PBS use, and sexual orientation. A final analytic sample (n = 2091) was composed of participants who indicated past 30-day marijuana use (60% women, 64% White, mean age 19.92). Path analysis was used to test all study hypothesis. Results indicated a curvilinear relation between sexual orientation and consequences among men, however not women. Moreover, PBS use mediated the relation between orientation and consequences among men, and negatively predicted consequences among women. Conclusions include that mixed sexual orientation men experience higher consequences through lower PBS use. For women, PBS use buffers against consequences. These findings reflect a general effectiveness of PBS use for mitigating negative marijuana-related consequences. The implications of these results are discussed.

Lifestyle choices and mental health: a longitudinal survey with German and Chinese students

BackgroundA healthy lifestyle can be beneficial for one’s mental health. Thus, identifying healthy lifestyle choices that promote psychological well-being and reduce mental problems is useful to prevent mental disorders. The aim of this longitudinal study was to evaluate the predictive values of a broad range of lifestyle choices for positive mental health (PMH) and mental health problems (MHP) in German and Chinese students.MethodData were assessed at baseline and at 1-year follow-up. Samples included 2991 German (Mage = 21.69, SD = 4.07) and 12,405 Chinese (Mage = 20.59, SD = 1.58) university students. Lifestyle choices were body mass index, frequency of physical and mental activities, frequency of alcohol consumption, smoking, vegetarian diet, and social rhythm irregularity. PMH and MHP were measured with the Positive Mental Health Scale and a 21-item version of the Depression Anxiety and Stress Scale. The predictive values of lifestyle choices for PMH and MHP at baseline and follow-up were assessed with single-group and multi-group path analyses.ResultsBetter mental health (higher PMH and fewer MHP) at baseline was predicted by a lower body mass index, a higher frequency of physical and mental activities, non-smoking, a non-vegetarian diet, and a more regular social rhythm. When controlling for baseline mental health, age, and gender, physical activity was a positive predictor of PMH, smoking was a positive predictor of MHP, and a more irregular social rhythm was a positive predictor of PMH and a negative predictor of MHP at follow-up. The good fit of a multi-group model indicated that most lifestyle choices predict mental health comparably across samples. Some country-specific effects emerged: frequency of alcohol consumption, for example, predicted better mental health in German and poorer mental health in Chinese students.ConclusionsOur findings underline the importance of healthy lifestyle choices for improved psychological well-being and fewer mental health difficulties. Effects of lifestyle on mental health are comparable in German and Chinese students. Some healthy lifestyle choices (i.e., more frequent physical activity, non-smoking, regular social rhythm) are related to improvements in mental health over a 1-year period.

Final size of a multi-group SIR epidemic model: Irreducible and non-irreducible modes of transmission

A model of an epidemic outbreak incorporating multiple subgroups of susceptible and infected individuals is investigated. The asymptotic behavior of the model is analyzed and it is proved that the infected classes all converge to 0. A computational algorithm is developed for the cumulative final size of infected individuals over the course of the epidemic. The results are applied to the SARS epidemic in Singapore in 2003, where it is shown that the two-peak evolution of the infected population can be attributed to a two-group formulation of transmission.

Psychological Well-Being, Multiple Identities, and Discrimination Among First and Second Generation Immigrant Muslims.

Given the growing number of Muslim immigrants in Western countries, there is a need for research focusing on their psychological well-being and correlates. The present study investigated whether perceived discrimination is associated with depression and satisfaction with migration through the mediating role of several identity dimensions (ethnic, national, and religious) among 204 first and second generation adult Muslim immigrants living in Italy. They participated in structured interviews, and a multi-group path analysis model was conducted using Mplus. While the impact of perceived discrimination on psychological well-being was modest for first generation Muslims, in the case of second generation Muslims perceived discrimination was directly associated with lower psychological well-being (higher depression and lower satisfaction with the migration decision) and indirectly associated with satisfaction with migration through the mediation of national and religious identity. The higher the levels of discrimination that second generation Muslims perceived, the weaker their national (host country) identity and the greater their religious identification. In turn, national and religious identities were associated with respectively higher and lower levels of satisfaction regarding their migration decision. The findings showed clear differences between first and second generation immigrant groups, revealing that perceived discrimination represents an obstacle to integration processes more for second generation immigrants than for first generations.

Epidemic model with group mixing: Stability and optimal control based on limited vaccination resources

We investigate the global dynamics of a multi-group SIR epidemic model. By using the Lyapunov-LaSalle principle, a graph-theoretic approach and the uniform persistence theory, the global dynamics can be obtained for both disease-free and endemic equilibria. The relationship of the basic reproduction ratios between the subgroup model and the mixed group model are established. The optimal control strategy of an infectious disease with the mixing of two sub-groups under limited vaccination resources is also studied. The results suggest that the optimal distribution strategies are dynamically different due to the variance of heterogeneity.

A modified multi-group model of angular and momentum distribution of cosmic ray muons for thickness measurement and material discrimination of slabs

Muon tomography is a capable imaging technique to measure the geometry of high-Z objects. However, most existed algorithms used in muon tomography have obscured the effects of angular distribution and momentum spectra of cosmic ray muons and reduced the spatial resolution. We present a modified multi-group model that takes into account these effects and calibrates the model by the material of lead. Performance tests establish that the model is capable of measuring the thickness of a Pb slab and identifying the material of an unknown slab on a reasonable exposure timescale, in both cases of complete and incomplete angular data. Results show that the modified multi-group model is helpful for improvements in image resolution in real applications.

Global stability of multi-group SEIRS epidemic models with vaccination

In this paper, a susceptible–exposed–infective–recovered–susceptible (SEIRS) epidemic model with vaccination has been formulated. We studied the global stability of the corresponding single-group model, multi-group model with strongly connected network and multi-group model without strongly connected network by means of analyzing their basic reproduction numbers and the application of Lyapunov functionals. Finally, we provide some numerical simulations to illustrate our analysis results.

Validating COMSOL multiphysics for VVER-1000 whole-core-steady-state via AER benchmark problem

In this work, a full core, three-dimensional, multi-group model of VVER-1000 reactor core is developed using specifications of the Schulz benchmark. This paper presents a new 3-D full core solution, and simulates the neutronic behaviour of the VVER-1000 reactor by predicting the system criticality, power distribution, and the neutron flux distribution. Multi-group constants are applied to the COMSOL model to perform neutronics calculations using finite element method with adaptive mesh refinement. The study found that the calculated effective multiplication factor (keff) compares well with the reference value. Furthermore, the fission rates 3D power distributions and axially averaged 2D power distribution are in good agreements with reported reference results. The thermal neutron spectrum is also calculated by the COMSOL model as presented in this paper. This study allows us to validate the COMSOL calculation schemes for VVER-type reactors and to compare our solutions with reference solutions at steady state.

Psychological Predictors of Sexual Intimate Partner Violence against Black and Hispanic Women.

Background: Although various types of intimate partner violence (IPV) tend to co-occur, risk factors of each type of IPV may differ. At the same time, most of the existing literature on risk factors of IPV among minorities has used a cross-sectional design and has focused on physical rather than sexual IPV. We conducted the current study to compare Black and Hispanic women for psychological predictors of change in sexual IPV over time. Methods: Using data from the Fragile Families and Child Wellbeing Study (FFCWS), this study followed 561 Black and 475 Hispanic women with their male partners for four years. Independent variables included male partners’ depression, anxiety, problem alcohol use, and male-to-female physical and psychological IPV perpetration. The dependent variable was sexual IPV reported by female partners, measured at baseline, two years, and four years later. Covariates included age, income, marital status and education level. We used a multi-group latent growth curve model (LGCM) to explain intercept, linear, and quadratic slopes, which represent the baseline, and linear and curvilinear trajectories of male-to-female sexual IPV, where groups were defined based on ethnicity. Results: Psychological IPV was associated with sexual IPV at baseline among both ethnic groups. The male partner’s depression was a risk factor for an increase in sexual IPV over time among Black but not Hispanic women. Anxiety, problem alcohol use and physical IPV did not have an effect on the baseline or change in sexual IPV over time. Psychological IPV was not associated with an increase in sexual IPV over time in either ethnic group. Conclusions: There is a need for screening of sexual IPV in the presence of psychological IPV among minority women. There is also a need for screening and treatment of male partners’ depression as a strategy to reduce sexual IPV among Black women.Background: Although various types of intimate partner violence (IPV) tend to co-occur, risk factors of each type of IPV may differ. At the same time, most of the existing literature on risk factors of IPV among minorities has used a cross-sectional design and has focused on physical rather than sexual IPV. We conducted the current study to compare Black and Hispanic women for psychological predictors of change in sexual IPV over time. Methods: Using data from the Fragile Families and Child Wellbeing Study (FFCWS), this study followed 561 Black and 475 Hispanic women with their male partners for four years. Independent variables included male partners’ depression, anxiety, problem alcohol use, and male-to-female physical and psychological IPV perpetration. The dependent variable was sexual IPV reported by female partners, measured at baseline, two years, and four years later. Covariates included age, income, marital status and education level. We used a multi-group latent growth curve model (LGCM) to explain intercept, linear, and quadratic slopes, which represent the baseline, and linear and curvilinear trajectories of male-to-female sexual IPV, where groups were defined based on ethnicity. Results: Psychological IPV was associated with sexual IPV at baseline among both ethnic groups. The male partner’s depression was a risk factor for an increase in sexual IPV over time among Black but not Hispanic women. Anxiety, problem alcohol use and physical IPV did not have an effect on the baseline or change in sexual IPV over time. Psychological IPV was not associated with an increase in sexual IPV over time in either ethnic group. Conclusions: There is a need for screening of sexual IPV in the presence of psychological IPV among minority women. There is also a need for screening and treatment of male partners’ depression as a strategy to reduce sexual IPV among Black women.

Multi-patch and multi-group epidemic models: a new framework.

We develop a multi-patch and multi-group model that captures the dynamics of an infectious disease when the host is structured into an arbitrary number of groups and interacts into an arbitrary number of patches where the infection takes place. In this framework, we model host mobility that depends on its epidemiological status, by a Lagrangian approach. This framework is applied to a general SEIRS model and the basic reproduction number [Formula: see text] is derived. The effects of heterogeneity in groups, patches and mobility patterns on [Formula: see text] and disease prevalence are explored. Our results show that for a fixed number of groups, the basic reproduction number increases with respect to the number of patches and the host mobility patterns. Moreover, when the mobility matrix of susceptible individuals is of rank one, the basic reproduction number is explicitly determined and was found to be independent of the latter if the matrix is also stochastic. The cases where mobility matrices are of rank one capture important modeling scenarios. Additionally, we study the global analysis of equilibria for some special cases. Numerical simulations are carried out to showcase the ramifications of mobility pattern matrices on disease prevalence and basic reproduction number.

Developmental Links Between Gaming and Depressive Symptoms.

The current longitudinal study tested the reciprocal relationships between video game play and depressive symptoms among 9,421 adolescents from the Add Health (Mage =16.15years, SD=1.64, 55% female), over 11years (Waves 2, 3, and 4), ages 16 to 27. Based on structural equationmodeling as well as latent growth models, findings indicated that (1) excessive gaming was largely transient over time, from adolescence to early adulthood; (2) excessive gaming predicted increases in depressive symptoms; and (3) in turn, depressive symptoms predicted decreases in gaming over time. Multigroup model tests by sex provided additional evidence that longitudinal relationships from excessive gaming to depressive symptoms were supported for male, but not for female youth.

A nonstandard finite difference scheme for a multi-group epidemic model with time delay

In this paper, we derive a discretized multi-group epidemic model with time delay by using a nonstandard finite difference (NSFD) scheme. A crucial observation regarding the advantage of the NSFD scheme is that the positivity and boundedness of solutions of the continuous model are preserved. Furthermore, we show that the discrete model has the same equilibria, and the conditions for their stability are identical in case of both the discrete and the corresponding continuous models. Specifically, if mathfrak{R}_{0}leq1, then the disease-free equilibrium P_{0} is globally asymptotically stable; if mathfrak{R}_{0}>1, then the infection equilibrium P_{*} is globally asymptotically stable. The results imply that the discretization scheme can efficiently preserve the global dynamics of the original continuous model.

Explaining between-race differences in African-American and European-American women's responses to breast density notification

BackgroundPrior research shows between-race differences in women's knowledge and emotions related to having dense breasts, thus suggesting that between-race differences in behavioral decision-making following receipt of breast density (BD) notifications are likely. Guided by the theory of planned behavior, this study examined differences in emotion-related responses (i.e., anxiety, worry, confusion) and behavioral cognition (e.g., intentions, behavioral attitudes) following receipt of BD notifications among African American (AA) and European American (EA) women. This study also examined whether race-related perceptions (i.e., discrimination, group-based medical mistrust), relevant knowledge and socioeconomic status (SES) explained the between race differences. MethodMichigan women (N = 457) who presented for routine screening mammogram and had dense breasts, no prior breast cancer diagnoses, and had screen-negative mammograms were recruited from July, 2015 to March 2016. MANOVA was used to examine between race differences in psychological responses (i.e., emotional responses and behavioral cognition), and a multi-group structural regression model was used to examine whether race-related constructs, knowledge and SES mediated the effect of race on emotional responses and behavioral cognition. Prior awareness of BD was accounted for in all analyses. ResultsAA women generally reported more negative psychological responses to receiving BD notifications regardless of prior BD awareness. AA women had more favorable perceptions related to talking to their physicians about the BD notifications. Generally, race-related perceptions, SES, and related knowledge partially accounted for the effect of race on psychological response. Race-related perceptions and SES partially accounted for the differences in behavioral intentions. Between-race differences in emotional responses to BD notifications did not explain differences in women's intentions to discuss BD notifications with their physicians. ConclusionsFuture examinations are warranted to examine whether there are between-race differences in actual post-BD notification behaviors and whether similar race-related variables account for differences.

Particle methods for multi-group pedestrian flow

We consider a multi-group microscopic model for pedestrian flow describing the behaviour of large groups. It is based on an interacting particle system coupled to an eikonal equation. Hydrodynamic multi-group models are derived from the underlying particle system as well as scalar multi-group models. The eikonal equation is used to compute optimal paths for the pedestrians. Particle methods are used to solve the equations on all levels of the hierarchy. Numerical test cases are investigated and the models and, in particular, the resulting evacuation times are compared for a wide range of different parameters.