Major depressive disorder(MDD)is a multifactorial disorder,where multiple susceptibility genes interact with environmental factors,predisposing individuals to the development of the illness.In this article,we reviewed...Major depressive disorder(MDD)is a multifactorial disorder,where multiple susceptibility genes interact with environmental factors,predisposing individuals to the development of the illness.In this article,we reviewed different gene×environment interaction(G×E)studies shifting from a candidate gene to a genome-wide approach.Among environmental factors,childhood adversities and stressful life events have been suggested to exert crucial impacts on MDD.Importantly,the diathesis-stress conceptualization of G×E has been challenged by the differential susceptibility theory.Finally,we summarized several limitations of G×E studies and suggested how future G×E studies might reveal complex interactions between genes and environments in MDD.展开更多
An SIS epidemiological model in a population of varying size with two dissimilar groups of susceptible individuals has been analyzed. We prove that all the solutions tend to the equilibria of the system. Then we use t...An SIS epidemiological model in a population of varying size with two dissimilar groups of susceptible individuals has been analyzed. We prove that all the solutions tend to the equilibria of the system. Then we use the Poincar~ Index theorem to determine the number of the rest points and their stability properties. It has been shown that bistability occurs for suitable values of the involved parameters. We use the perturbations of the pitchfork bifurcation points to give examples of all possible dynamics of the system. Some numerical examples of bistability and hysteresis behavior of the systeIn has been also provided.展开更多
Epidemics of infectious diseases have been known to recur in time.Diseases like influenza,despite intervention efforts through vaccination and targeted social distancing,continue to persist intermittently in the popul...Epidemics of infectious diseases have been known to recur in time.Diseases like influenza,despite intervention efforts through vaccination and targeted social distancing,continue to persist intermittently in the population.I have undertaken an analysis of a stochastic epidemic model with the hypothesis that intervention drives epidemic cycles.Intervention indeed is found to induce cycles of epidemic activity.Above a minimum intervention rate,however,activity dies out in finite time.The susceptibility structure of a community could be easily infused into the design of existing surveillance protocols.By tracking that structure,early detection of an impending outbreak is enhanced.展开更多
We formulate and systematically study a deterministic compartmental model of Hepatitis B.This model has some important and novel features compared with the well-known basic model in the literature.Specifically,it take...We formulate and systematically study a deterministic compartmental model of Hepatitis B.This model has some important and novel features compared with the well-known basic model in the literature.Specifically,it takes into account the differential susceptibility that follows the vaccine formulation employing three-doses schedule.It points up the HbeAg status of carriers,their levels of viral replication,the fact that treatment being not curative is recommended only to a small proportion of chronic carriers,and finally the fact that only inactive carriers are able to recover from disease.The model has simple dynamical behavior which has a globally asymptotically stable disease-free equilibrium when the basic reproduction number R0≤1 and an endemic equilibrium when R0>1.By the use of Lyapunov functions,when it exists,we prove the global asymptotic stability of the endemic equilibrium under some conditions.Using data from Tokombere,a rural area in Cameroon,numerical simulations are performed.These numerical simulations first confirm analytical results,second they suggest that a policy based on treatment could not significantly impact the course of the infection.Third,they show as it is well known that vaccination is a very effective measure to control the infection.Furthermore,they show that neonatal vaccination influences more the course of infection than mass vaccination strategy.Nevertheless,they picture how much loss between consecutive doses of vaccine could be harmful.Finally,it is suggested that for a Sub-saharan African rural area,two-thirds of expected incidence of Hepatitis B virus infection and one third of expected prevalence of chronic carriers could be averted by 2030 if the birth dose vaccination becomes systematic and if mass vaccination rate increases to up 10%.展开更多
文摘Major depressive disorder(MDD)is a multifactorial disorder,where multiple susceptibility genes interact with environmental factors,predisposing individuals to the development of the illness.In this article,we reviewed different gene×environment interaction(G×E)studies shifting from a candidate gene to a genome-wide approach.Among environmental factors,childhood adversities and stressful life events have been suggested to exert crucial impacts on MDD.Importantly,the diathesis-stress conceptualization of G×E has been challenged by the differential susceptibility theory.Finally,we summarized several limitations of G×E studies and suggested how future G×E studies might reveal complex interactions between genes and environments in MDD.
文摘An SIS epidemiological model in a population of varying size with two dissimilar groups of susceptible individuals has been analyzed. We prove that all the solutions tend to the equilibria of the system. Then we use the Poincar~ Index theorem to determine the number of the rest points and their stability properties. It has been shown that bistability occurs for suitable values of the involved parameters. We use the perturbations of the pitchfork bifurcation points to give examples of all possible dynamics of the system. Some numerical examples of bistability and hysteresis behavior of the systeIn has been also provided.
基金support from the Ateneo Scholarly Work Grant SOSE 172012the National Research Council of the Philippines(NRCP)Grant B-108.
文摘Epidemics of infectious diseases have been known to recur in time.Diseases like influenza,despite intervention efforts through vaccination and targeted social distancing,continue to persist intermittently in the population.I have undertaken an analysis of a stochastic epidemic model with the hypothesis that intervention drives epidemic cycles.Intervention indeed is found to induce cycles of epidemic activity.Above a minimum intervention rate,however,activity dies out in finite time.The susceptibility structure of a community could be easily infused into the design of existing surveillance protocols.By tracking that structure,early detection of an impending outbreak is enhanced.
文摘We formulate and systematically study a deterministic compartmental model of Hepatitis B.This model has some important and novel features compared with the well-known basic model in the literature.Specifically,it takes into account the differential susceptibility that follows the vaccine formulation employing three-doses schedule.It points up the HbeAg status of carriers,their levels of viral replication,the fact that treatment being not curative is recommended only to a small proportion of chronic carriers,and finally the fact that only inactive carriers are able to recover from disease.The model has simple dynamical behavior which has a globally asymptotically stable disease-free equilibrium when the basic reproduction number R0≤1 and an endemic equilibrium when R0>1.By the use of Lyapunov functions,when it exists,we prove the global asymptotic stability of the endemic equilibrium under some conditions.Using data from Tokombere,a rural area in Cameroon,numerical simulations are performed.These numerical simulations first confirm analytical results,second they suggest that a policy based on treatment could not significantly impact the course of the infection.Third,they show as it is well known that vaccination is a very effective measure to control the infection.Furthermore,they show that neonatal vaccination influences more the course of infection than mass vaccination strategy.Nevertheless,they picture how much loss between consecutive doses of vaccine could be harmful.Finally,it is suggested that for a Sub-saharan African rural area,two-thirds of expected incidence of Hepatitis B virus infection and one third of expected prevalence of chronic carriers could be averted by 2030 if the birth dose vaccination becomes systematic and if mass vaccination rate increases to up 10%.
