The Adaptive Significance of Natural Genetic Variation in the DNA Damage Response of Drosophila melanogaster.

Despite decades of work, our understanding of the distribution of fitness effects of segregating genetic variants in natural populations remains largely incomplete. One form of selection that can maintain genetic variation is spatially varying selection, such as that leading to latitudinal clines. While the introduction of population genomic approaches to understanding spatially varying selection has generated much excitement, little successful effort has been devoted to moving beyond genome scans for selection to experimental analysis of the relevant biology and the development of experimentally motivated hypotheses regarding the agents of selection; it remains an interesting question as to whether the vast majority of population genomic work will lead to satisfying biological insights. Here, motivated by population genomic results, we investigate how spatially varying selection in the genetic model system, Drosophila melanogaster, has led to genetic differences between populations in several components of the DNA damage response. UVB incidence, which is negatively correlated with latitude, is an important agent of DNA damage. We show that sensitivity of early embryos to UVB exposure is strongly correlated with latitude such that low latitude populations show much lower sensitivity to UVB. We then show that lines with lower embryo UVB sensitivity also exhibit increased capacity for repair of damaged sperm DNA by the oocyte. A comparison of the early embryo transcriptome in high and low latitude embryos provides evidence that one mechanism of adaptive DNA repair differences between populations is the greater abundance of DNA repair transcripts in the eggs of low latitude females. Finally, we use population genomic comparisons of high and low latitude samples to reveal evidence that multiple components of the DNA damage response and both coding and non-coding variation likely contribute to adaptive differences in DNA repair between populations

Coalitions and Cliques in the School Choice Problem

The school choice mechanism design problem focuses on assignment mechanisms matching students to public schools in a given school district. The well-known Gale Shapley Student Optimal Stable Matching Mechanism (SOSM) is the most efficient stable mechanism proposed so far as a solution to this problem. However its inefficiency is well-documented, and recently the Efficiency Adjusted Deferred Acceptance Mechanism (EADAM) was proposed as a remedy for this weakness. In this note we describe two related adjustments to SOSM with the intention to address the same inefficiency issue. In one we create possibly artificial coalitions among students where some students modify their preference profiles in order to improve the outcome for some other students. Our second approach involves trading cliques among students where those involved improve their assignments by waiving some of their priorities. The coalition method yields the EADAM outcome among other Pareto dominations of the SOSM outcome, while the clique method yields all possible Pareto optimal Pareto dominations of SOSM. The clique method furthermore incorporates a natural solution to the problem of breaking possible ties within preference and priority profiles. We discuss the practical implications and limitations of our approach in the final section of the article

Evidence for elevated emissions from high-latitude wetlands contributing to high atmospheric CH4 concentration in the early Holocene

The major increase in atmospheric methane (CH4) concentration during the last glacial-interglacial transition provides a useful example for understanding the interactions and feedbacks among Earth\u27s climate, biosphere carbon cycling, and atmospheric chemistry. However, the causes of CH4 doubling during the last deglaciation are still uncertain and debated. Although the ice-core data consistently suggest a dominant contribution from northern high-latitude wetlands in the early Holocene, identifying the actual sources from the ground-based data has been elusive. Here we present data syntheses and a case study from Alaska to demonstrate the importance of northern wetlands in contributing to high atmospheric CH4concentration in the early Holocene. Our data indicate that new peatland formation as well as peat accumulation in northern high-latitude regions increased more than threefold in the early Holocene in response to climate warming and the availability of new habitat as a result of deglaciation. Furthermore, we show that marshes and wet fens that represent early stages of wetland succession were likely more widespread in the early Holocene. These wetlands are associated with high CH4 emissions due to high primary productivity and the presence of emergent plant species that facilitate CH4 transport to the atmosphere. We argue that early wetland succession and rapid peat accumulation and expansion (not simply initiation) contributed to high CH4 emissions from northern regions, potentially contributing to the sharp rise in atmospheric CH4 at the onset of the Holocene

A Systematic Key Management Mechanism for Practical Body Sensor Networks

Security plays a vital role in promoting the practicality of Wireless Body Sensor Networks (BSNs), which provides a promising solution to precise human physiological status monitoring. A fundamental security issue in BSN is key management, including establishment and maintenance of the key system. However, current BSN key management solutions are either designed for specific phases of a BSN’s life-time or restricted to strong assumptions such as homogeneous BSN composition, pre-deployed key materials, and existing secure path, which limits their applications in real-world BSNs. In this paper, we develop the Systematic Key Management (SKM) for practical BSNs, where basic human interactions are conducted for non-predeployed secure BSN initialization, and authenticated key agreement is achieved using lightweight non-pairing certificateless public key cryptography. We construct a BSN prototype consisting of selfdesigned motes and Android phones to evaluate the real-world performance of SKM. Through extensive simulations and test-bed experiments, we demonstrate that our lightweight SKM scheme manages to provide high security guarantee while outperforming state-of-the-art approaches in terms of both computation and storage efficiency

High School Bridge Program: A Multidisciplinary STEM Research Program

A Science, Technology, Engineering and Math (STEM) summer Bridge Program was developed for high school students. The program was designed to encourage students to consider choosing an engineering major in college and to explore STEM as a future career. This was accomplished through a 10-week program involving multidisciplinary research activities. The participants in the program included 33 high school students. Among former participants in position to make a choice in terms of attending college, 100% had chosen to continue on in college, and 86% had chosen to major in a STEM area. The results indicated that that the program had enhanced their confidence in STEM and motivated them in choosing careers in STEM areas. Overall, the participants were very positive about the program and expressed appreciation for the opportunity

An Evaluation of a STEM Program for Middle School Students on Learning Disability Related IEPs

A year long Science, Technology, Engineering and Math (STEM) program was developed for middle schools students on Individualized Education Programs (IEPs) involving learning disabilities. The workshops were designed to encourage students both on IEPs and not on IEPs to explore STEM as a future career choice by building their knowledge and confidence. The participants in the workshops included 11 students on IEPs and 15 students not on IEPs. Parents also provided feedback regarding their attitudes toward the program. The results indicated that there were increases in student participant knowledge and career interest for both the students not on IEPs and the students on IEPs. Overall, reactions to the program from both students and parents were quite positive

A review of consumer awareness, understanding and use of food-based dietary guidelines

Copyright @ 2011 Cambridge University PressFood-based dietary guidelines (FBDG) have primarily been designed for the consumer to encourage healthy, habitual food choices, decrease chronic disease risk and improve public health. However, minimal research has been conducted to evaluate whether FBDG are utilised by the public. The present review used a framework of three concepts, awareness, understanding and use, to summarise consumer evidence related to national FBDG and food guides. Searches of nine electronic databases, reference lists and Internet grey literature elicited 939 articles. Predetermined exclusion criteria selected twenty-eight studies for review. These consisted of qualitative, quantitative and mixed study designs, non-clinical participants, related to official FBDG for the general public, and involved measures of consumer awareness, understanding or use of FBDG. The three concepts of awareness, understanding and use were often discussed interchangeably. Nevertheless, a greater amount of evidence for consumer awareness and understanding was reported than consumer use of FBDG. The twenty-eight studies varied in terms of aim, design and method. Study quality also varied with raw qualitative data, and quantitative method details were often omitted. Thus, the reliability and validity of these review findings may be limited. Further research is required to evaluate the efficacy of FBDG as a public health promotion tool. If the purpose of FBDG is to evoke consumer behaviour change, then the framework of consumer awareness, understanding and use of FBDG may be useful to categorise consumer behaviour studies and complement the dietary survey and health outcome data in the process of FBDG evaluation and revision.This study is funded by the European Commission Sixth Framework Programme (contract no. 036196)

The use of quantitative Real-Time PCR to estimate Salmonella shed in fecal samples from naturally infected finishing pigs

The objective of this study was to describe the shedding pattern of Salmonella in finishing pigs, as well to quantify the Salmonella load. A longitudinal study was conducted in 12 cohorts of pigs in a multi-site farrow-to-finish production system. At the beginning of each cohort, 50 pigs (10 ± 2 weeks old) were randomly selected and individually identified. Individual pig fecal samples were collected and cultured every 2 weeks for 16 weeks (8 collections)