Trophic plasticity of omnivorous fishes in natural and human‐dominated landscapes

The persistence of diverse communities and functioning ecosystems under increasing anthropogenic pressure relies on food web rewiring and the ability of animals to expand or change their diet in disturbed ecosystems. We combined a suite of diet tracing techniques to study trophic plasticity in omnivorous fishes, ecomorphologically similar species with high competition potential, across different human land uses in subtropical streams. We found that the proportion of native forest cover, associated with intensive land use, altered the isotopic composition of fishes, which were more enriched in 13C, without affecting the carbon isotope ratios of their prey and basal resources. There was also evidence for a nonlinear effect of native forest cover on the δ15N values of basal resources, macroinvertebrates, and omnivorous fishes, indicating that nutrient pollution from agriculture propagated through stream food webs. The most widely distributed fish species shifted their diet from autochthonous resources to terrestrial invertebrates and sedimentary organic matter in disturbed streams. Moreover, the isotopic niche of this fish species was broader in streams with higher fish species richness, indicating the combined impacts of environmental change and competition on species coexistence. Therefore, our findings showed that the dominance and trophic niche breadth of dominant omnivores depend not only on the availability of resources but also on the interactions with their putative competitors

A feasibility trial to examine the social norms approach for the prevention and reduction of licit and illicit drug use in European University and college students.

Background: Incorrect perceptions of high rates of peer alcohol and tobacco use are predictive of increased personal use in student populations. Correcting misperceptions by providing feedback has been shown to be an effective intervention for reducing licit drug use. It is currently unknown if social norms interventions are effective in preventing and reducing illicit drug use in European students. The purpose of this paper is to describe the design of a multi-site cluster controlled trial of a web-based social norms intervention aimed at reducing licit and preventing illicit drug use in European university students. Methods/Design: An online questionnaire to assess rates of drug use will be developed and translated based on existing social norms surveys. Students from sixteen universities in seven participating European countries will be invited to complete the questionnaire. Both intervention and control sites will be chosen by convenience. In each country, the intervention site will be the university that the local principal investigator is affiliated with. We aim to recruit 1000 students per site (baseline assessment). All participants will complete the online questionnaire at baseline. Baseline data will be used to develop social norms messages that will be included in a web-based intervention. The intervention group will receive individualized social norms feedback. The website will remain online during the following 5 months. After five months, a second survey will be conducted and effects of the intervention on social norms and drug use will be measured in comparison to the control site. Discussion: This project is the first cross-national European collaboration to investigate the feasibility of a social norms intervention to reduce licit and prevent illicit drug use among European university students. Final trial registration number DRKS00004375 on the ‘German Clinical Trials Register’.This study is funded by the European Commission, Directorate General Justice, Freedom and Security (JLS/2009-2010/DPIP/AG

Neurospora from natural populations: Population genomics insights into the Life history of a model microbial Eukaryote

The ascomycete filamentous fungus Neurospora crassa played a historic role in experimental biology and became a model system for genetic research. Stimulated by a systematic effort to collect wild strains initiated by Stanford geneticist David Perkins, the genus Neurospora has also become a basic model for the study of evolutionary processes, speciation, and population biology. In this chapter, we will first trace the history that brought Neurospora into the era of population genomics. We will then cover the major contributions of population genomic investigations using Neurospora to our understanding of microbial biogeography and speciation, and review recent work using population genomics and genome-wide association mapping that illustrates the unique potential of Neurospora as a model for identifying the genetic basis of (potentially adaptive) phenotypes in filamentous fungi. The advent of population genomics has contributed to firmly establish Neurospora as a complete model system and we hope our review will entice biologists to include Neurospora in their research

Chemical speciation of nanoparticles surrounding metal-on-metal hips.

Spectromicroscopy of tissue surrounding failed CoCr metal-on-metal hip replacements detected corroded nanoscale debris in periprosthetic tissue in two chemical states, with concomitant mitochondrial damage. The majority of debris contained Cr(3+), with trace amounts of oxidised cobalt. A minority phase containing a core of metallic chromium and cobalt was also observed

Emerging Infectious Disease leads to Rapid Population Decline of Common British Birds

Emerging infectious diseases are increasingly cited as threats to wildlife, livestock and humans alike. They can threaten geographically isolated or critically endangered wildlife populations; however, relatively few studies have clearly demonstrated the extent to which emerging diseases can impact populations of common wildlife species. Here, we report the impact of an emerging protozoal disease on British populations of greenfinch Carduelis chloris and chaffinch Fringilla coelebs, two of the most common birds in Britain. Morphological and molecular analyses showed this to be due to Trichomonas gallinae. Trichomonosis emerged as a novel fatal disease of finches in Britain in 2005 and rapidly became epidemic within greenfinch, and to a lesser extent chaffinch, populations in 2006. By 2007, breeding populations of greenfinches and chaffinches in the geographic region of highest disease incidence had decreased by 35% and 21% respectively, representing mortality in excess of half a million birds. In contrast, declines were less pronounced or absent in these species in regions where the disease was found in intermediate or low incidence. Also, populations of dunnock Prunella modularis, which similarly feeds in gardens, but in which T. gallinae was rarely recorded, did not decline. This is the first trichomonosis epidemic reported in the scientific literature to negatively impact populations of free-ranging non-columbiform species, and such levels of mortality and decline due to an emerging infectious disease are unprecedented in British wild bird populations. This disease emergence event demonstrates the potential for a protozoan parasite to jump avian host taxonomic groups with dramatic effect over a short time period

A novel ultra-high strength maraging steel with balanced ductility and creep resistance achieved by nanoscale β-NiAl and Laves phase precipitates

A novel ultra-high strength precipitation hardened martensitic steel with balanced ductility and creep resistance has been developed. It utilises a unique combination of nanometre scale intermetallic precipitates of Laves phases and β-NiAl to achieve such properties. The mechanical properties of this steel were assessed by tensile and creep testing. With different heat treatments, this steel showed a remarkable combination of mechanical properties: yield strength of >1800 MPa, ultimate tensile strength of ~ 2000 MPa, tensile ductility up to ~8% at room temperature and creep rupture life > 2,000 hours under 700 MPa stress at 500 °C. The microstructures at different length scales were characterised using scanning / transmission electron microscopy and atom probe tomography. The austenisation and ageing temperatures were found be the key factors determining the microstructural development and resulting mechanical properties. Large primary Laves phase precipitates formed at lower austenisation temperatures resulted in reduced creep strength; whilst the small difference (20 °C) in ageing temperatures had significant impact on the spatial distribution characteristics of β-NiAl precipitates. Lower ageing temperature produced much smaller but more uniformly distributed β-NiAl precipitates which contributed to the higher observed yield strength. It is clear from this study that whilst this novel alloy system showed great potentials, careful design of heat treatment is still required to achieve balanced mechanical properties to meet the service requirements in aerospace propulsion systems

Comparison of deferral rates using a computerized versus written blood donor questionnaire: a randomized, cross-over study [ISRCTN84429599]

BACKGROUND: Self-administered computer-assisted blood donor screening strategies may elicit more accurate responses and improve the screening process. METHODS: Randomized crossover trial comparing responses to questions on a computerized hand-held tool (HealthQuiz, or HQ), to responses on the standard written instrument (Donor Health Assessment Questionnaire, or DHAQ). Randomly selected donors at 133 blood donation clinics in the area of Hamilton, Canada participated from 1995 to 1996. Donors were randomized to complete either the HQ or the DHAQ first, followed by the other instrument. In addition to responses of 'yes' and 'no' on both questionnaires, the HQ provided a response option of 'not sure'. The primary outcome was the number of additional donors deferred by the HQ. RESULTS: A total of 1239 donors participated. Seventy-one potential donors were deferred as a result of responses to the questionnaires; 56.3% (40/71) were deferred by the DHAQ, and an additional 43.7% (31/71) were deferred due to risks identified by the HQ but not by the DHAQ. Fourteen donors self-deferred; 11 indicated on the HQ that they should not donate blood on that day but did not use the confidential self-exclusion option on the DHAQ, and three used the self-exclusion option on the DHAQ but did not indicate that they should not donate blood on the HQ. The HQ identified a blood contact or risk factor for HIV/AIDS or sexually transmitted infection that was not identified by the DHAQ in 0.1% to 2.7% of donors. CONCLUSION: A self-administered computerized questionnaire may increase risk reporting by blood donors

oA novel nonparametric approach for estimating cut-offs in continuous risk indicators with application to diabetes epidemiology

<p>Abstract</p> <p>Background</p> <p>Epidemiological and clinical studies, often including anthropometric measures, have established obesity as a major risk factor for the development of type 2 diabetes. Appropriate cut-off values for anthropometric parameters are necessary for prediction or decision purposes. The cut-off corresponding to the Youden-Index is often applied in epidemiology and biomedical literature for dichotomizing a continuous risk indicator.</p> <p>Methods</p> <p>Using data from a representative large multistage longitudinal epidemiological study in a primary care setting in Germany, this paper explores a novel approach for estimating optimal cut-offs of anthropomorphic parameters for predicting type 2 diabetes based on a discontinuity of a regression function in a nonparametric regression framework.</p> <p>Results</p> <p>The resulting cut-off corresponded to values obtained by the Youden Index (maximum of the sum of sensitivity and specificity, minus one), often considered the optimal cut-off in epidemiological and biomedical research. The nonparametric regression based estimator was compared to results obtained by the established methods of the Receiver Operating Characteristic plot in various simulation scenarios and based on bias and root mean square error, yielded excellent finite sample properties.</p> <p>Conclusion</p> <p>It is thus recommended that this nonparametric regression approach be considered as valuable alternative when a continuous indicator has to be dichotomized at the Youden Index for prediction or decision purposes.</p