Orbitofrontal Cortex Assigns Credit Wisely

Damage in the orbitofrontal cortex impairs the ability to switch behaviors when their outcomes change, but the cause of these deficits remained unknown. In this issue of Neuron, Walton et al. demonstrate a key role of the primate orbitofrontal cortex in disambiguating the relationship between multiple choices and their outcomes

Economics of Spot Instance Service: A Two-stage Dynamic Game Apporach

This paper presents the economic impacts of spot instance service on the cloud service providers (CSPs) and the customers when the CSPs offer it along with the on-demand instance service to the customers. We model the interaction between CSPs and customers as a non-cooperative two-stage dynamic game. Our equilibrium analysis reveals (i) the techno-economic interrelationship between the customers' heterogeneity, resource availability, and CSPs' pricing policy, and (ii) the impacts of the customers' service selection (spot vs. on-demand) and the CSPs' pricing decision on the CSPs' market share and revenue, as well as the customers' utility. The key technical challenges lie in, first, how we capture the strategic interactions between CSPs and customers, and second, how we consider the various practical aspects of cloud services, such as heterogeneity of customers' willingness to pay for the quality of service (QoS) and the fluctuating resource availability. The main contribution of this paper is to provide CSPs and customers with a better understanding of the economic impact caused by a certain price policy for the spot service when the equilibrium price, which from our two-stage dynamic game analysis, is able to set as the baseline price for their spot service

Mathematical Modeling and Simulation for Epidemic Models

Department of Mathematical ScienceMathematical modeling has been important to explore transmission dynamics and construct effective control strategies to prevent the spread of disease. Most simple mathematical model is deterministic model. However, we need to take account into the stochastic model when the system involves the intrinsic fluctuations or randomness. Moreover, stochastic models can capture exactly the dynamics of individuals in a small population. But generally, it is difficult to solve the stochastic system. Since bio-chemical reaction is described according to the law of mass action which is used to construct epidemic model. We derive the explicit formula of the solution in terms of block matrices. We formulate mathematical models for epidemic disease. Then, we apply the stochastic computational methods such as the stochastic simulation algorithm (SSA) and the moment closure method (MCM) to the model. First, we apply the stochastic methods to an disease transmission model with government$'$s control policies against the 2009 H1N1 influenza in Korea. We investigate the impact of various vaccination and antiviral treatment intervention scenarios to prevent the spread of disease. As the result, it is verified that the earlier vaccination is more effective. Second, we consider the two-strain dengue transmission model with seasonality for sequential infection. Despite of having no autochthonous dengue outbreaks in Korea, the potential risk of dengue transmission in Jeju Island increases. We investigate the possible impacts of the potential outbreak of dengue fever in Jeju Island considering climate change based on Representative Concentration Pathways (RCP) scenarios and the migration of infected international travel. Finally, if there are a small number of cases at the initial stage of the epidemic. Infection processes occur randomly. Transmission dynamics involve the probabilistic properties in the system. Therefore, stochastic model provides more accurate predictions. We compare the dynamics of epidemic outbreaks quantitatively under stochastic and deterministic models. We investigate that as the initial number of infectives increases, the difference between the deterministic and stochastic solutions decreases.ope

Potential effects of climate change on dengue transmission dynamics in Korea

Dengue fever is a major international public health concern, with more than 55% of the world population at risk of infection. Recent climate changes related to global warming have increased the potential risk of domestic outbreaks of dengue in Korea. In this study, we develop a two-strain dengue model associated with climate-dependent parameters based on Representative Concentration Pathway (RCP) scenarios provided by the Korea Meteorological Administration. We assess the potential risks of dengue outbreaks by means of the vector capacity and intensity under various RCP scenarios. A sensitivity analysis of the temperature-dependent parameters is performed to explore the effects of climate change on dengue transmission dynamics. Our results demonstrate that a higher temperature significantly enhances the potential threat of domestic dengue outbreaks in Korea. Furthermore, we investigate the effects of countermeasures on the cumulative incidence of humans and vectors. The current main control measures (comprising only travel restrictions) for infected humans in Korea are not as effective as combined control measures (travel restrictions and vector control), dramatically reducing the possibilities of dengue outbreaks

Identifying geographic areas at risk of rubella epidemics in Japan using seroepidemiological data

Objective Even with relatively high vaccination coverage, Japan experienced rubella epidemics in 2012-2014 and 2018-2019, which were fueled by untraced imported cases. We aimed to develop a risk map for rubella epidemics in Japan by geographic location via analysis of seroepidemiological data and accounting for the abundance of foreign visitors. Methods Geographic age distribution and seroprevalence were used to compute the age- and sex-dependent next-generation matrix in each region. We computed the probability of a major epidemic using the assumed number of untraced imported rubella cases proportionally modeled to the number of foreign travelers. Results Risks of a major epidemic were high in areas with capital cities, while areas with a greater fraction of older people yielded smaller effective reproduction numbers, a lower volume of foreign travelers, and thus a lower probability of a major epidemic. The volume of susceptible adult males was larger in urban geographic regions, having a greater number of foreign travelers than remote areas. Conclusions Our findings are consistent with the observation of multiple large clusters of rubella cases in urban areas during 2012-2014 and 2018-2019. Should a future rubella epidemic occur, it will likely be in geographic areas with capital cities

Evaluation of a phenology-dependent response method for estimating leaf area index of rice across cllimate gradients

Accurate estimate of the seasonal leaf area index (LAI) in croplands is required for understanding not only intra- and inter-annual crop development, but also crop management. Lack of consideration in different growth phases in the relationship between LAI and vegetation indices (VI) often results in unsatisfactory estimation in the seasonal course of LAI. In this study, we partitioned the growing season into two phases separated by maximum VI ( VI max ) and applied the general regression model to the data gained from two phases. As an alternative method to capture the influence of seasonal phenological development on the LAI-VI relationship, we developed a consistent development curve method and compared its performance with the general regression approaches. We used the Normalized Difference VI (NDVI) and the Enhanced VI (EVI) from the rice paddy sites in Asia (South Korea and Japan) and Europe (Spain) to examine its applicability across different climate conditions and management cycles. When the general regression method was used, separating the season into two phases resulted in no better estimation than the estimation obtained with the entire season observation due to an abrupt change in seasonal LAI occurring during the transition between the before and after VI max . The consistent development curve method reproduced the seasonal patterns of LAI from both NDVI and EVI across all sites better than the general regression method. Despite less than satisfactory estimation of a local LAI max , the consistent development curve method demonstrates improvement in estimating the seasonal course of LAI. The method can aid in providing accurate seasonal LAI as an input into ecological process-based models

Geospatial Clustering Analysis on Drug Abuse Emergencies

The epidemic of drug abuse is a serious public health issue in the U.S. The number of overdose deaths involving prescription opioids and illicit drugs has continuously increased over the last few years. This study aims to develop a geospatial model that identifies geospatial clusters in terms of socioeconomic and demographic characteristics with an unsupervised machine learning algorithm. Then, we suggest the most important features affecting heroin overdose both negatively and positively. The findings of this study may inform policymakers about strategies to mitigate the drug overdose crisis

Geospatial Clustering Analysis on Drug Abuse Emergencies

The epidemic of drug abuse is a serious public health issue in the U.S. The number of overdose deaths involving prescription opioids and illicit drugs has continuously increased over the last few years. This study aims to develop a geospatial model that identifies geospatial clusters in terms of socioeconomic and demographic characteristics with an unsupervised machine learning algorithm. Then, we suggest the most important features affecting heroin overdose both negatively and positively. The findings of this study may inform policymakers about strategies to mitigate the drug overdose crisis

Spatial clustering of heroin-related overdose incidents: a case study in Cincinnati, Ohio

Drug overdose is one of the top leading causes of accidental death in the U.S., largely due to the opioid epidemic. Although the opioid epidemic is a nationwide issue, it has not affected the nation uniformly