Multi-group Model Research Articles

Investigations on the hohlraum radiation in the first shaped laser pulse implosion experiment at the SGIII laser facility

The first 0.1 MJ scale shaped pulse implosion experiment was performed at the Shenguang-III laser facility in 2016. The hohlraum radiation of three representative shots with troughs of 1.0 ns, 1.5 ns, and 2.5 ns is analysed using the two-dimensional code LARED with the multi-group radiation transfer model. It is found that the simulated multi-angle radiation temperatures are generally in good agreement with the measurements within ∼3%. However, our simulations underestimate the peak radiation temperature at 64° by ∼6% for the shot with the 2.5 ns trough, due to the much smaller laser entrance hole in our calculations. In addition, we simulate the time-integrated M-band (2–4 keV) x-ray image at the view angle of 20° for the shot with the 1.0 ns trough. The simulated laser spot positions are consistent with the measurement. But the relative brightness between the inner beams and the outer beams is larger than the experimental result, which may be caused by the overestimation of the plasma density at the edge of the bubbles in our simulation. With the bubble contribution approximately removed, the simulated relative brightness between the inner beams and the outer beams approaches the experimental result.

Examining Pathways between Bully Victimization, Depression, & School Belonging Among Early Adolescents

The relationship between bully victimization and depression has been examined extensively with prior research showing long-term cascade of problems stemming from both exposure to victimization and depressive symptomology. However, prior research has failed to consider how protective factors may mitigate these long-term problems. Three theoretical models were tested: the interpersonal risk model, symptom driven model, and transactional model. The present study employs a novel statistical technique to explore longitudinal reciprocal associations among bullying, depression, and school belonging in a sample of 2177 middle school students (ages 11 to 15) in a Midwestern state. We used a model building process to explore the overall association between bully victimization, depression, and school belonging as well as a multi-group model in which models were estimated for boys and girls, separately. In our overall model, results indicated support for both symptom driven and interpersonal risk models. However, we did not find any significant buffering effect of school belonging. In our multi-group model, we found support for a buffering effect of school belonging for girls, but not boys. School belonging buffered long term problems associated with experiences of bully victimization via reductions in depression. Our findings point to the broader concept of school structure being differentially supportive and protective for various demographic groups and the need to consider the entire social ecology of a school when planning and implementing prevention interventions.

Antecedents of satisfaction and engagement of low-carbon bicycle-sharing using in China.

Transport sector contributed numerous carbon emissions in China. It is important to promote low-carbon bicycle-sharing using in China. This paper aims to analyze the influencing factors of the satisfaction and engagement of bicycle-sharing in China. An extended model of customer satisfaction is established, which considers both customer satisfaction theory and customer engagement theory. We explore the different effect of convenience, health, safety, and facility on satisfaction of bicycle-sharing using. We also explore the role of satisfaction on three different dimensions of engagement: enthusiasm, participation, and social interaction. Multi-group structure equation model is employed to explore the different roles of gender on the determinants of satisfaction and engagement of bicycle-sharing using. The findings reveal that facilities had the larger effect on satisfaction of bicycle-sharing using than safety and health for male. Safety had the largest influence on satisfaction of bicycle-sharing using for female, followed by facility, convenience, and health.

Extending poly-victimization theory: Differential effects of adolescents' experiences of victimization on substance use disorder diagnoses upon treatment entry.

Although victimization is a known contributor to the development of substance use disorders, no research has simultaneously examined how characteristics of victimization experienced over time, such as the type of abuse, the presence of poly-victimization, closeness to perpetrator(s), life threat or fear, and negative social reactions to disclosing victimization, cluster into profiles that predict substance use disorders. The aim of the current study is to assess how profiles of victimization and trauma characteristics are associated with substance use disorders and assess potential gender differences. Participants were 20,092 adolescents entering substance use treatment. We used latent class and multi-group latent class analysis to extract classes of victimization and associated characteristics. Emergent classes were used to predicted substance use disorder status at treatment intake. Five classes were extracted: poly-victimization + high harmful trauma characteristics, sexual abuse + negative social reaction and perceived life threat, emotional abuse + trusted perpetrator, physical abuse and low all. Similar classes were found for the multi-group model. In both the overall and female-specific models, the poly-victimization + high harmful trauma characteristics class was more severe than all other classes in terms of opioid use disorder, tobacco use disorder, and dual diagnosis. Other class differences were found across gender. Adolescents entering treatment can be distinguished by their profiles of victimization experiences and associated characteristics, and these profiles evidence different associations with substance use disorder diagnoses. Results point to a need for more nuanced assessment of victimization experiences and gender-specific interventions.

CONVAL: A Measurement Model for Assessing Consumer-Perceived Firm-Generated Content Value in Social Media

The rise of social media increased the necessity for firms to establish a presence on platforms like Facebook, Instagram, and Twitter. As a means to engage with consumers, firms create content for their fan pages (i.e., firm-generated content). In this context, publishing content that is perceived as valuable by consumers is crucial to achieve a firm’s advertising goals. However, marketers are insecure about what consumers perceive as valuable and how to measure it. Current literature lacks of an appropriate model that measures consumers’ perceived value of firm-generated content in social media and guides marketers in content creation. Based on a solid conceptualization, an extensive explorative study, and a large-scale study using 902 U.S. users of Facebook, Instagram, and Twitter, the author develops and validates CONVAL — a 4-dimensional second-order measurement model including 17 items to assess firm-generated content value in social media. The results indicate a reliable and valid instrument, which is applicable by researches and practitioners. In addition, the author calculates a multi-group model, revealing that marketers should particularly pay attention to emphasize informative content on Twitter, entertaining content on Instagram, and empathic content on Facebook.

Global dynamics for a multi-group alcoholism model with public health education and alcoholism age.

A new multi-group alcoholism model with public health education and alcoholism age is considered. The basic reproduction number R₀ is defined and mathematical analyses show that dynamics of model are determined by the basic reproduction number. The alcohol-free equilibrium P₀ of the model is globally asymptotically stable if R₀≤1 while the alcohol-present equilibrium P* of the model exists uniquely and is globally asymptotically stable if R₀>1. The Lyapunov functionals for the globally asymptotically stable of the multi-group model are constructed by using the theory of non-negative matrices and a graph-theoretic approach. Meanwhile, the combined effects of the public health education and the alcoholism age on alcoholism dynamics are displayed. Our main results show that strengthening public health education and decreasing the age of the alcoholism are very helpful for the control of alcoholism.

Dynamical analysis of an age-structured multi-group SIVS epidemic model.

Host heterogeneities such as space, gender, and age etc are intrinsic characters for investigating diseases mechanisms and transmission routes. First, we incorporate inter-group, intra-group and age structure to propose a multi-group SIVS epidemic model. Then we obtain the basic reproduction number of the system which is the spectral radius of the next generation operator by the renewal equation. Based on some assumptions for parameters, we obtain the existence and uniqueness of endemic equilibrium. By means of integral semigroup theory and Lyapunov methods, we show that the threshold dynamics of the system is completely determined by the basic.

Global stability of multi-group SIR epidemic model with group mixing and human movement.

In this paper, an SIR multi-group epidemic model with group mixing and human movement is investigated. The control reproduction number ℜυ is derived and the global dynamics of the model are completely determined by the value of ℜυ. By using the graph-theoretical approach, the results show that the disease-free equilibrium is globally asymptotically stable if ℜυ<1, and the unique endemic equilibrium is globally asymptotically stable if ℜυ>1. Two numerical examples are further presented to testify the validity of the theoretical results.

A multi-group model for estimating the transmission rate of hand, foot and mouth disease in mainland China.

In order to access the influence of different age groups on the spread of hand, foot and mouth disease (HFMD), we established the multi-group model with migration following the epidemiology of HFMD. The basic reproduction number of the HFMD epidemic model was calculated by the next generation operator method. According to China's national surveillance data on HFMD, we fitted the model parameters and estimated the transmission rates among different age groups. Besides, we carried out sensitivity analysis for the basic reproduction number to find some valuable regulatory measures. Our findings showed that the children under three years of age were indeed at high risk and adult group who had more contacts with children had a crucial influence on the spread of HFMD.

Disability Self-Identification and Well-Being in Emerging Adults

Research suggests that emerging adults (EAs) with a disabling impairment experience poor psychosocial outcomes and delayed markers of adulthood. Given the numbers of EA with a disabling impairment who do not self-identify as having a disability, we examine a multigroup structural model of positive disability identity based on disability self-identification. Participants ( n = 2,016) completed assessments of positive disability identity, psychosocial outcomes, and markers of adulthood. Most participants with a disabling impairment did not self-identify as having a disability (68%). Positive disability identity, maintaining a positive view of disability, was associated with increased life satisfaction, regardless of whether EA self-identify as having a disability. Exploratory analyses suggest that EA with psychiatric disabilities experience the most negative psychosocial outcomes. Findings suggest that maintaining a positive view of disability is associated with favorable outcomes. However, intervention with EA who do not self-identify is challenging, as they may not seek support services.

Global Behavior of a Multi-Group SIR Epidemic Model with Age Structure and an Application to the Chlamydia Epidemic in Japan

In this paper, we are concerned with the global behavior of a multi-group SIR epidemic model with age structure. A similar model was studied in [T. Kuniya, J. Wang, and H. Inaba, Discrete Contin. D...

Transmission dynamics of acute respiratory diseases in a population structured by age.

Determining the role of age on the transmission of an infection is a topic that has received significant attention. In this work, a dataset of acute respiratory infections structured by age from San Luis Potosí, Mexico, is analyzed to understand the age impact on this class of diseases. To do that, a compartmental SEIRS multigroup model is proposed to describe the infection dynamics among age groups. Then, a Bayesian inference approach is used to estimate relevant parameters in the model such as the probability of infection, the average time that one individual remains infectious, the average time that one individual remains immune, and the force of infection, among others. Based on those estimates, our analysis leads us to conclude that children less than 5 years old are the primary spreaders of respiratory infections in San Luis Potosí's population from 2000 to 2008 since they are more prone to get sick, remain infectious for longer periods and they are reinfected more rapidly. On the other hand, the group of young adults (20-59) is the one that differs the most from the little children's group because it does not get sick often, it remains infectious only a few days and it stays healthy for longer periods. These observations allow us to infer that the group of young adults is the one that, on average, less contributed to the spread of this class of infections during the years represented in our database.

The coupled neutron transport calculation of Monte Carlo multi-group and continuous cross section

It is well known that Monte Carlo neutron transport calculation based on the continuous cross section is with high precision, but the computing time is too long and memory consumption is large relative to the multi-group calculation. In contrast, the multi-group calculation is good both in terms of speed and memory relative the continuous calculation, but the short appears on S(α,β) and resonance energy region. For combining the advantages of these two models, we firstly develop the collision mechanism based on material. Then the coupled model is investigated based on the multi-group and continuous. The continuous model was employed to treat the thermal and resonance energy ranges, the multi-group model uses in the other energy ranges. Different energy ranges are coupled through the neutron scattering and fission contributions between each other. We chose the ITER 1-D sphere model for test example. This example contains a great amount of hydrogen, deep-subcritical and involves thermal scattering and resonance. The result of continuous model is as standard. The cases of criticality fission source and fixed source are considered. The comparison shows good agreement between coupled and continuous model. The speedup of coupled model increases about two times relative continuous model. The validity of coupled model has been proved by numerical simulation.

Numerical simulation of remote infrared imaging for marine exhaust system using wide-band k-distribution model combined with a new grouping method for spectral sub-intervals

In previous work, spectral sub-interval grouping was used to improve the prediction accuracies of k-distribution models for the radiation transfer characteristics of strong non-isothermal gases. This improvement was realized by eliminating the temperature-difference-induced destruction of correlated-k characteristics of the gas absorption spectra. In the present work, the influence of participating-species mole-ratio inhomogeneities on the correlated-k characteristics of the gas absorption spectra was treated by establishing a new object function. This function was used to optimize the group division of spectral sub-intervals through matching overlapping parameter calculation performed in a multi-scale multi-group wide-band k-distribution model. The performance of the new object function was evaluated through a series of one-dimensional (1D) cases, where the radiances under 2–2.5-µm, 3–5-µm, and 8–14-µm wave bands emitted by a combustion gas, which contained water vapor, carbon dioxide, and carbon monoxide (i.e., the participating species), were attenuated by ambient air with lower temperature and quite different mole ratios of these participating species. Finally, evaluations are presented on the calculation of remote sensing thermal images of the exhaust system of a marine gas turbine using hydrocarbon fuel with ejection cooling system of solid wall.

Slow-fast analysis of a multi-group asset flow model with implications for the dynamics of wealth.

The multi-group asset flow model is a nonlinear dynamical system originally developed as a tool for understanding the behavioral foundations of market phenomena such as flash crashes and price bubbles. In this paper we use a modification of this model to analyze the dynamics of a single-asset market in situations when the trading rates of investors (i.e., their desire to exchange stock for cash) are prescribed ahead of time and independent of the state of the market. Under the assumption of fast trading compared to the time-rate of change in the prescribed trading rates we decompose the dynamics of the system to fast and slow components. We use the model to derive a variety of observations regarding the dynamics of price and investors’ wealth, and the dependence of these quantities on the prescribed trading rates. In particular, we show that strategies with constant trading rates, which represent the well-known constant-rebalanced portfolio (CRP) strategies, are optimal in the sense that they minimize investment risks. In contrast, we show that investors pursuing non-CRP strategies are at risk of loss of wealth, as a result of the slow system not being integrable in the sense that cyclic trading rates do not always result in periodic price variations.

Explaining self-reported traffic crashes of cyclists: An empirical study based on age and road risky behaviors

The growing rates of traffic crashes involving cyclists are currently recognized as a major public health and road safety concern. Furthermore, risky behaviors on the road and their precedent factors have been conceptualized as potential determinants for explaining, intervening and preventing traffic injuries of cyclists. ObjectivesThis study aimed at examining whether individual factors and self-reported risky behaviors could explain the crash rates of cyclists in a period of 5 years. MethodsA sample of 1064 cyclists was used, with a mean age of 32.83 years. Participants answered a survey assessing demographic data and information on risky behaviors, risk perception, knowledge of norms, and suffered cycling crashes. ResultsUsing Structural Equation Models, it was found that crash rates in cyclists could be explained through risky behaviors, risk perception, knowledge of traffic norms and cycling intensity. Through a multi-group path model differentiating cyclists by age group, it was also found that cycling intensity has a differential impact on self-reported crashes in older (age > 25) and younger (age<=25) cyclists. ConclusionsThis study suggests that risky behaviors mediate the relationship between the individual factors and the crash rates of cyclists, and that age exerts an important effect in the variation of the explanatory structure of the model. The design of educational tools would be useful for promoting not only the avoidance of risky behaviors, but also a generalized awareness on road safety issues. Practical applicationsThis research provides an empirical precedent in the study of the impact of factors related to risky behaviors on the road and to safety outcomes of cyclists.

Emotional and physical maltreatment, early maladaptive schemas, and internalizing disorders in adolescents: a multi-group path model of clinical and non-clinical samples

Many studies have supported the mediating role of maladaptive schemas in the relationship between early childhood adversity and psychopathology in both clinical and non-clinical adolescent samples. However, to the best of our knowledge, there has been no study to simultaneously test the mediating role of maladaptive schemas in a combined model included in both clinical and non-clinical samples of adolescents. The sample of the study consisted of 132 non-clinical (M = 15.65, SD = 1.15) and 193 clinically referred (M = 15.05, SD = 1.07) adolescents. Criteria for the clinical sample included being diagnosed with generalized anxiety disorder, depressive disorder or mixed anxiety and depressive disorder. Participants were administered The Childhood Trauma Questionnaire, Young Schema Questionnaire, Children’s Depression Inventory, and Spielberger State-Trait Anxiety Inventory. The aim of the present study was to test the hypothesized mediation model that Disconnection/Rejection and Impaired Autonomy schema domains would mediate the relationship between childhood maltreatment and psychological symptoms for clinical and non-clinical adolescent samples, separately. Furthermore, we tested whether structural paths of the model were different across the two samples, using multiple-group path analysis. Results showed that Disconnection/Rejection and Impaired Autonomy emerged as significant mediators in both samples. In addition, only the association between Disconnection/Rejection and depression was stronger in the clinical sample compared to the non-clinical sample.

Analysis of an age-structured multi-group heroin epidemic model

This paper is concerned with the mathematical analysis of an age-structured multi-group heroin epidemic model, which can be used to describe the spread of heroin habituation and addiction in heterogeneous environment. Under general assumptions on the different level of susceptibility and the relapse to frequent heroin use, we establish sharp criteria for heroin spreading and vanishing. We rigorously investigate the well-posedness of the model, the existence of equilibria, the asymptotic smoothness of solution orbits, and the global stability of equilibria. Specifically, we rigorously show that the drug-free equilibrium is globally asymptotically stable if a threshold value ℜ0 is less than one, and the unique drug-endemic equilibrium is globally attractive if ℜ0 is greater than one. In the proofs of global stability of equilibria, we construct suitable Lyapunov functions by using a graph-theoretic method.

Toward a better assessment of perceived social influence: The relative role of significant others on young athletes.

The purpose of this three-study paper was to develop and validate the Perceived Social Influence in Sport Scale-2 (PSISS-2) that aimed to resolve the limitations of PSISS-1 in assessing the relative social influence of significant others in youth sport. In Study 1, a pool of 60 items generated from revisiting a qualitative dataset about significant others of young athletes were examined by two expert panel reviews in terms of content validity, clarity, coverage, and age-appropriateness, leading to the development of 16 items of the PSISS-2. In Study 2, multi-group exploratory structural equation model for PSISS-2 was conducted among 904 young athletes, and the results supported a model comprising positive influence (ie, conditional and unconditional positive influence combined), punishment (ie, conditional negative influence), and dysfunction (ie, unconditional negative influence) as three factors. The goodness of fit of the three-factor model was acceptable and invariant across the coach-, father-, mother-, and teammates-versions of PSISS-2. In support of the criterion validity of PSISS-2, the three factors explained substantial variance of young athletes' perceived competence, effort, enjoyment, and trait anxiety in sport. Study 3 examined the relationship between PSISS-2 factors, psychological need support, and controlling behaviors in a subsample of 452 young athletes, and the findings supported the concurrent validity and discriminant validity of the scale. In conclusion, the data are supportive of PSISS-2. The three factors of the scale (ie, positive influence, punishment, and dysfunction) may form a new framework for understanding and comparing the relative role of significant others in youth sport.

The Relationship Between Development Trajectories of Resilience and Social Support Systems Among Early Adolescents: Applications of Latent Class Growth Analysis and Multiple-Group Growth Mixture Modeling

Objectives Resilience is characterized by the ability to change over time and may increase or decrease in adolescence depending on available social support factors. In this study, we investigated trajectories of resilience and how these longitudinal patterns of resilience are related to changes in social relationships over time. Methods This longitudinal study analyzed 4,299 early adolescents from waves 3-6 (sixth year of elementary school to third year of middle school) of the Seoul Education Longitudinal Study (SELS). A latent class growth analysis (LCGA) was conducted to empirically demonstrate latent development trajectories of adolescents’ resilience, and growth mixture model with known class was created to describe the relationship between resilience development trajectories and longitudinal change in social support systems (parent relationships, teacher relationships, peer relationships). Results First, the developmental patterns of adolescents’ resilience varied over time; a total of six latent development trajectories were identified. The initial values of resilience by latent group were distributed over a wide range (high, middle-high, middle, middle-low, and low) and rate of change showed various patterns (decrease, decrease-increase, increase, and increase-decrease). Second, the patterns of change in social relationships (parents, teachers, peers) were similar to those of the resilience development trajectories. Third, among the three dimensions of social support, peer relationships showed the most similar patterns of change over time compared with other resilience development trajectories. Conclusions Based on the results of this study, differentiated interventions are required depending on the latent development trajectories of resilience, and adolescents should be provided with various opportunities to establish positive relationships with parents, teachers, and peers. Keywords: resilience, social support systems, latent class growth analysis, multi-group growth mixture model