Evidence for inbreeding depression in a species with limited opportunity for maternal effects

It is often assumed that mating with close relatives reduces offspring fitness. In such cases, reduced offspring fitness may arise from inbreeding depression (i.e., genetic effects of elevated homozygosity) or from post-mating maternal investment. This can be due to a reduction in female investment after mating with genetically incompatible males ("differential allocation") or compensation for incompatibility ("reproductive compensation"). Here, we looked at the effects of mating with relatives on offspring fitness in mosquitofish, Gambusia holbrooki. In this species, females are assumed to be nonplacental and to allocate resources to eggs before fertilization, limiting differential allocation. We looked at the effects of mating with a brother or with an unrelated male on brood size, offspring size, gestation period, and early offspring growth. Mating with a relative reduced the number of offspring at birth, but there was no difference in the likelihood of breeding, gestation time, nor in the size or growth of these offspring. We suggest that due to limited potential for maternal effects to influence these traits that any reduction in offspring fitness, or lack thereof, can be explained by inbreeding depression rather than by maternal effects. We highlight the importance of considering the potential role of maternal effects when studying inbreeding depression and encourage further studies in other Poeciliid species with different degrees of placentation to test whether maternal effects mask or amplify any genetic effects of mating with relatives.This work was supported bythe Australian Research Council (DP120100339). R.V.-T. is supported by fellowships from Consejo Nacion-al de Ciencia y Tecnologıa-Mexico and the ResearchSchool of Biology

Simulating corporate income tax reform proposals with a dynamic CGE model

Opinion leaders and policy makers in the United States have turned their focus to the corporate income tax, which now has the highest statutory rate in the developed world. Using a dynamic computable general equilibrium model (the “NCPA-DCGE Model”), we simulate alternative policies for reducing the U.S. corporate income tax. We find that reductions in the corporate income tax rate result in significant positive impacts on output, investment, capital formation, employment, and household well-being (for almost all deciles). All of the hypothesized reforms also result in a more-streamlined public sector. These results are plausible insofar as the DCGE model from which they are obtained is parameterized by plausible elasticity assumptions, and incorporates the adjustments in prices, output, employment and investment that result from changes in tax policy

Defending the right to protest

Amid rising global protests, the right to protest is being increasingly objected to by business interests and curtailed by governments and legislatures. This article contends that confronted by this political reaction, the right to protest can only be defended through mass struggles rather than legal challenges – although these struggles may well include related legal battles. As history suggests, while legal cases may be important at times, ultimately their outcome will be determined by the sway and swell of political social and class forces

Are sexually selected traits affected by a poor environment early in life?

Background: Challenging conditions experienced early in life, such as a restricted diet, can detrimentally affect key life-history traits. Individuals can reduce these costs by delaying their sexual maturation, albeit at the price of the later onset of breeding, to eventually reach the same adult size as individuals that grow up in a benevolent environment. Delayed maturation can, however, still lead to other detrimental morphological and physiological changes that become apparent later in adulthood (e.g. shorter lifespan, faster senescence). In general, research focuses on the naturally selected costs of a poor early diet. In mosquitofish (Gambusia holbrooki), males with limited food intake early in life delay maturation to reach a similar adult body size to their well-fed counterparts (‘catch-up growth’). Here we tested whether a poor early diet is costly due to the reduced expression of sexually selected male characters, namely genital size and ejaculate traits. Results: We found that a male’s diet early in life significantly influenced his sperm reserves and sperm replenishment rate. Shortly after maturation males with a restricted early diet had significantly lower sperm reserves and slower replenishment rates than control diet males, but this dietary difference was no longer detectable in older males. Conclusions: Although delaying maturation to reach the same body size as well fed juveniles can ameliorate some costs of a poor start in life, our findings suggest that costs might still arise because of sexual selection against these males. It should be noted, however, that the observed effects are modest (Hedges’ g = 0.20-0.36), and the assumption that lower sperm production translates into a decline in fitness under sperm competition remains unconfirmed

Change Blindness in Web Applications

Design practitioners have long believed that web interfaces are at a disadvantage compared to desktop interfaces because the web page model may cause change blindness more than non-page based interfaces. To evaluate this concern, a within-subjects experiment was set up to test various change types in a mock web application. User performance was better when a page loaded as normal and when elements changed instantly on screen compared to a half-second flicker change type. However, change detection rates were only 5% greater and response times only 0.1 second faster for the instant change compared to page loading. This shows that there is some change blindness effect due to the Web's page-by-page architecture, but it is not nearly as disconcerting as practitioners have long believed. Furthermore, single page applications that minimize full-page refreshes may help reduce the incidence of change blindness on the web.Master of Science in Information Scienc

Systematic analysis of funding awarded for norovirus research to institutions in the United Kingdom, 1997-2010

Objectives:Norovirus infections pose great economic and disease burden to health systems around the world. This study quantifies the investments in norovirus research awarded to UK institutions over a 14-year time period.Design:A systematic analysis of public and philanthropic infectious disease research investments awarded to UK institutions between 1997 and 2010.Participants:NoneSetting:UK institutions carrying out infectious disease research.Main outcome measures:Total funding for infectious disease research, total funding for norovirus research, position of norovirus research along the R&amp;D value chain.Results:The total dataset consisted of 6165 studies with sum funding of £2.6 billion. Twelve norovirus studies were identified with a total funding of £5.1 million, 0.2% of the total dataset. Of these, eight were categorized as pre-clinical, three as intervention studies and one as implementation research. Median funding was £200,620.Conclusions:Research funding for norovirus infections in the UK appears to be unacceptably low, given the burden of disease and disability produced by these infections. There is a clear need for new research initiatives along the R&amp;D value chain: from pre-clinical through to implementation research, including trials to assess cost-effectiveness of infection control policies as well as clinical, public health and environmental interventions in hospitals, congregate settings and in the community.</p

Failure of Harmonic Gears During Verification of a Two-Axis Gimbal for the Mars Reconnaissance Orbiter Spacecraft

The Mars Reconnaissance Orbiter (MRO) spacecraft has three two-axis gimbal assemblies that support and move the High Gain Antenna and two solar array wings. The gimbal assemblies are required to move almost continuously throughout the mission's seven-year lifetime, requiring a large number of output revolutions for each actuator in the gimbal assemblies. The actuator for each of the six axes consists of a two-phase brushless dc motor with a direct drive to the wave generator of a size-32 cup-type harmonic gear. During life testing of an actuator assembly, the harmonic gear teeth failed completely, leaving the size-32 harmonic gear with a maximum output torque capability less than 10% of its design capability. The investigation that followed the failure revealed limitations of the heritage material choices that were made for the harmonic gear components that had passed similar life requirements on several previous programs. Additionally, the methods used to increase the stiffness of a standard harmonic gear component set, while accepted practice for harmonic gears, is limited in its range. The stiffness of harmonic gear assemblies can be increased up to a maximum stiffness point that, if exceeded, compromises the reliability of the gear components for long life applications

Inbreeding depression does not increase after exposure to a stressful environment: a test using compensatory growth

BACKGROUND: Inbreeding is often associated with a decrease in offspring fitness (‘inbreeding depression’). Moreover, it is generally assumed that the negative effects of inbreeding are exacerbated in stressful environments. This G × E interaction has been explored in many taxa under different environmental conditions. These studies usually manipulate environmental conditions either in adulthood or throughout an individual’s entire life. Far fewer studies have tested how stressful environments only experienced during development subsequently influence the effects of inbreeding on adult traits. RESULTS: We experimentally manipulated the diet (control versus low food) of inbred and outbred juvenile Eastern mosquitofish (Gambusia holbrooki) for three weeks (days 7-28) to test whether experiencing a presumably stressful environment early in life influences their subsequent growth and adult phenotypes. The control diet was a standard laboratory food regime, while fish on the low food diet received less than 25 % of this amount of food. Unexpectedly, despite a large sample size (237 families, 908 offspring) and a quantified 23 % reduction in genome-wide heterozygosity in inbred offspring from matings between full-siblings (f = 0.25), neither inbreeding nor its interaction with early diet affected growth trajectories, juvenile survival or adult size. Individuals did not mitigate a poor start in life by showing ‘compensatory growth’ (i.e. faster growth once the low food treatment ended), but they showed ‘catch-up growth’ by delaying maturation. There was, however, no effect of inbreeding on the extent of catch-up growth. CONCLUSIONS: There were no detectable effects of inbreeding on growth or adult size, even on a low food diet that should elevate inbreeding depression. Thus, the long-term costs of inbreeding due to lower male reproductive success we have shown in another study appear to be unrelated to inbreeding depression for adult male size or the growth rates that are reported in the current study.This work was supported by the Australian Research Council (DP160100285). R.V.-T. is supported by fellowships from Consejo Nacional de Ciencia y Tecnología-México and the Research School of Biology

How Emotional Intelligence Affects LMX Relationships

This study explored the utility of emotional intelligence (EI) as a predictor of leader-member exchange (LMX). To date, there has been very little research exploring the relationship between these constructs. It was hypothesized that EI in both supervisors and employees would have positive relationships with employee-rated LMX quality. A study was conducted with 24 working students at a Southeastern University and their supervisors at work. The Wong and Law Emotional Intelligence Scale and LMX-7 were administered to participants along with a measure of the Big Five. Pearson correlation and multiple regression analyses did not demonstrate support for the hypothesized relationships. There was weak to no support that employee EI predicted employee-rated LMX (r = .16) within a larger sample obtained in the study but was not statistically significant within the 24 dyads examined. The results of this study suggest that if a relationship does exist between EI and LMX, it is likely to be small. Some support was also offered for supervisor-employee similarity of EI being a predictor of employee-rated LMX scores