Social Identity and Inequality--The Impact of China’s Hukou System

We conduct an experimental study to investigate the causal impact of social identity on individuals? response to economic incentives. We focus on China?s decades old household registration system, or the hukou institution, which categorizes citizens into urban and rural residents, and favors the former over the latter in resource allocation. Our results indicate that making individuals? hukou status salient and public significantly reduces the performance of rural migrant students on an incentivized cognitive task by 10 percent. This leads to a leftward shift of their earnings distribution – the proportion of rural migrants below the 25th earnings percentile increases significantly by almost 19 percentage points. However, among non-migrants the proportion with earnings below the 25th percentile drops by 5 percentage points, and the proportion above the 75th percentile increases by almost 8 percentage points, albeit insignificantly. The results demonstrate the impact of institutionally imposed social identity on individuals? intrinsic response to incentives, and consequently on widening income inequality.social identity, hukou, inequality, field experiment, China

ETEA: A euclidean minimum spanning tree-Based evolutionary algorithm for multiobjective optimization

© the Massachusetts Institute of TechnologyAbstract The Euclidean minimum spanning tree (EMST), widely used in a variety of domains, is a minimum spanning tree of a set of points in the space, where the edge weight between each pair of points is their Euclidean distance. Since the generation of an EMST is entirely determined by the Euclidean distance between solutions (points), the properties of EMSTs have a close relation with the distribution and position information of solutions. This paper explores the properties of EMSTs and proposes an EMST-based Evolutionary Algorithm (ETEA) to solve multiobjective optimization problems (MOPs). Unlike most EMO algorithms that focus on the Pareto dominance relation, the proposed algorithm mainly considers distance-based measures to evaluate and compare individuals during the evolutionary search. Specifically in ETEA, four strategies are introduced: 1) An EMST-based crowding distance (ETCD) is presented to estimate the density of individuals in the population; 2) A distance comparison approach incorporating ETCD is used to assign the fitness value for individuals; 3) A fitness adjustment technique is designed to avoid the partial overcrowding in environmental selection; 4) Three diversity indicators-the minimum edge, degree, and ETCD-with regard to EMSTs are applied to determine the survival of individuals in archive truncation. From a series of extensive experiments on 32 test instances with different characteristics, ETEA is found to be competitive against five state-of-the-art algorithms and its predecessor in providing a good balance among convergence, uniformity, and spread.Engineering and Physical Sciences Research Council (EPSRC) of the United Kingdom under Grant EP/K001310/1, and the National Natural Science Foundation of China under Grant 61070088

Modeling TB-HIV syndemic and treatment

Tuberculosis (TB) and human immunodeficiency virus (HIV) can be considered a deadly human syndemic. In this article, we formulate a model for TB and HIV transmission dynamics. The model considers both TB and acquired immune deficiency syndrome (AIDS) treatment for individuals with only one of the infectious diseases or both. The basic reproduction number and equilibrium points are determined and stability is analyzed. Through simulations, we show that TB treatment for individuals with only TB infection reduces the number of individuals that become co-infected with TB and HIV/AIDS, and reduces the diseases (TB and AIDS) induced deaths. Analogously, the treatment of individuals with only AIDS also reduces the number of co-infected individuals. Further, TB-treatment for co-infected individuals in the active and latent stage of TB disease, implies a decrease of the number of individuals that passes from HIV-positive to AIDS.Comment: This is a preprint of a paper whose final and definite form is: Journal of Applied Mathematics (ISSN 1110-757X) 2014, Article ID 248407, http://dx.doi.org/10.1155/2014/24840

Patterns of Participation and Motivation in Folding@home: The Contribution of Hardware Enthusiasts and Overclockers

Folding@home is a distributed computing project in which participants run protein folding simulations on their computers. Participants complete work units and are awarded points for their contribution. An investigation into motivations to participate and patterns of participation revealed the significant contribution of a sub-community composed of individuals who custom-build computers to maximise their processing power. These individuals, known as “overclockers” or “hardware enthusiasts,” use distributed computing projects such as Folding@home to benchmark their modified computers and to compete with one another to see who can process the greatest number of project work units. Many are initially drawn to the project to learn about computer hardware from other overclockers and to compete for points. However, once they learn more about the scientific outputs of Folding@home, some participants become more motivated by the desire to contribute to scientific research. Overclockers form numerous online communities where members collaborate and help each other maximise their computing output. They invest heavily in their computers and process the majority of Folding@home’s simulations, thus providing an invaluable (and free) resource

Observations on the Overwintering Potential of the Striped Cucumber Beetle (Coleoptera: Chrysomelidae) in Southern Minnesota

The striped cucumber beetle, Acalymma vittatum (Fabricius) (Coleoptera: Chrysomelidae), is an important pest of cucurbit crops. However, the overwinter- ing capacity of this pest in temperate regions is poorly understood. In this study, the in-field survival of A. vittatum was examined during three consecutive winters. In addition, the supercooling points of A. vittatum were determined as an index of cold hardiness for adults. During each winter, the survival of adults decreased significantly through time, with no individuals surviving until spring. By comparing the supercooling points and in-field survival of adults to soil temperatures, it appears that winter temperatures in Minnesota are cold enough to induce freezing of the beetles. Moreover, a considerable amount of mortality occurred before minimum monthly soil temperatures dropped below the supercooling point of overwintering individuals, suggesting the occurrence of prefreeze mortality. An improved understanding of the response of A. vittatum to winter temperatures in temperate regions may aid in early season management of this pest

Sensory Compensation in Children Following Vision Loss after Trauma and Disease

Sensory compensation or sensory substitution occurs when a sense organ, such as the eye, is lost due to trauma or disease. Individuals often experience phantom limb sensation or pain but research increasingly points towards some individuals developing a heightened level of functioning in their remaining senses, particularly in their remaining intact eye. Losing an eye at an early age can often result in “super functioning” in the remaining eye providing that no similar trauma or disease results. Cases include young children who have undergone enucleation because of diagnosed unilateral retinoblastoma and whose remaining eye is free from disease