104 research outputs found

    Diet of the black backed jackal Canis mesomelas in the central Namib Desert, South West Africa

    Get PDF
    The diet of Canis mesomelas was studied in the central Namib Desert, South West Africa. A sample of 772 scats was collected from three main sites (coastal, dry riverine and open plains) and two minor sites (Diamond Area 2). Scats from the coastal site contained predominantly bird material whereas scats from the riverine and plains sites contained predominantly plant material. The present study is compared with other feeding studies of this species, particularly in South Africa

    Aspects of the biology of a rare redfm minnow, Barbus burchelli (pisces, Cyprinidae), from South Africa

    Get PDF
    Burchell's redfin, Barbus burchelli is endemic to the Breede River and adjacent smaller river systems in the Cape Province. Negative human influences have led to a drastic decline in numbers of this medium-sized minnow, especially agricultural demand on the water resource and the introduction of exotic predatory fish. The breeding season is extended, from September to February, with a peak in December. The absolute fecundity of a 123 mm FL specimen was 10 678, which includes both mature and recruitment ova. Females grow larger (123 mm FL), and live longer (6 +years), than males (113 mm FL and 4 + years). B. burchelli grow rapidly in their first year attaining a length of between 40 and 50 mm FL. Pronounced conical tubercles of sexually mature males erupt in spring, begin to show signs of wear in November and by March are worn or sloughed off. The survival of this species is dependent upon proper management of the Breede River system

    Associations between infant fungal and bacterial dysbiosis and childhood atopic wheeze in a nonindustrialized setting.

    Get PDF
    BACKGROUND: Asthma is the most prevalent chronic disease of childhood. Recently, we identified a critical window early in the life of both mice and Canadian infants during which gut microbial changes (dysbiosis) affect asthma development. Given geographic differences in human gut microbiota worldwide, we studied the effects of gut microbial dysbiosis on atopic wheeze in a population living in a distinct developing world environment. OBJECTIVE: We sought to determine whether microbial alterations in early infancy are associated with the development of atopic wheeze in a nonindustrialized setting. METHODS: We conducted a case-control study nested within a birth cohort from rural Ecuador in which we identified 27 children with atopic wheeze and 70 healthy control subjects at 5 years of age. We analyzed bacterial and eukaryotic gut microbiota in stool samples collected at 3 months of age using 16S and 18S sequencing. Bacterial metagenomes were predicted from 16S rRNA data by using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States and categorized by function with Kyoto Encyclopedia of Genes and Genomes ontology. Concentrations of fecal short-chain fatty acids were determined by using gas chromatography. RESULTS: As previously observed in Canadian infants, microbial dysbiosis at 3 months of age was associated with later development of atopic wheeze. However, the dysbiosis in Ecuadorian babies involved different bacterial taxa, was more pronounced, and also involved several fungal taxa. Predicted metagenomic analysis emphasized significant dysbiosis-associated differences in genes involved in carbohydrate and taurine metabolism. Levels of the fecal short-chain fatty acids acetate and caproate were reduced and increased, respectively, in the 3-month stool samples of children who went on to have atopic wheeze. CONCLUSIONS: Our findings support the importance of fungal and bacterial microbiota during the first 100 days of life on the development of atopic wheeze and provide additional support for considering modulation of the gut microbiome as a primary asthma prevention strategy

    The handbook for standardised field and laboratory measurements in terrestrial climate-change experiments and observational studies

    Get PDF
    Climate change is a worldwide threat to biodiversity and ecosystem structure, functioning, and services. To understand the underlying drivers and mechanisms, and to predict the consequences for nature and people, we urgently need better understanding of the direction and magnitude of climate‐change impacts across the soil–plant–atmosphere continuum. An increasing number of climate‐change studies is creating new opportunities for meaningful and high‐quality generalisations and improved process understanding. However, significant challenges exist related to data availability and/or compatibility across studies, compromising opportunities for data re‐use, synthesis, and upscaling. Many of these challenges relate to a lack of an established “best practice” for measuring key impacts and responses. This restrains our current understanding of complex processes and mechanisms in terrestrial ecosystems related to climate change

    Highly-parallelized simulation of a pixelated LArTPC on a GPU

    Get PDF
    The rapid development of general-purpose computing on graphics processing units (GPGPU) is allowing the implementation of highly-parallelized Monte Carlo simulation chains for particle physics experiments. This technique is particularly suitable for the simulation of a pixelated charge readout for time projection chambers, given the large number of channels that this technology employs. Here we present the first implementation of a full microphysical simulator of a liquid argon time projection chamber (LArTPC) equipped with light readout and pixelated charge readout, developed for the DUNE Near Detector. The software is implemented with an end-to-end set of GPU-optimized algorithms. The algorithms have been written in Python and translated into CUDA kernels using Numba, a just-in-time compiler for a subset of Python and NumPy instructions. The GPU implementation achieves a speed up of four orders of magnitude compared with the equivalent CPU version. The simulation of the current induced on 10^3 pixels takes around 1 ms on the GPU, compared with approximately 10 s on the CPU. The results of the simulation are compared against data from a pixel-readout LArTPC prototype

    β-diversity of deep-sea holothurians and asteroids along a bathymetric gradient (NE Atlantic)

    Get PDF
    Measuring and understanding patterns of ?-diversity remain major challenges in community ecology. Recently, ?-diversity has been shown to consist of 2 distinct components: (1) spatial turnover and (2) species loss leading to nestedness. Both components structure deep-sea macrofaunal assemblages but vary in importance among taxa and ocean basins and with energy availability. Here, we present the first evidence for turnover and nestedness along a bathymetric gradient in 2 major megafaunal taxa, holothurians and asteroids. Turnover is the dominant component of ?-diversity throughout bathyal and abyssal zones in both taxa, despite major differences in ?-diversity and trophic composition. High spatial turnover suggests a role for evolutionary adaptation to environmental circumstances within depth bands. This pattern differs fundamentally from those in some macrofaunal groups in low-energy environments where abyssal nestedness is high and diversity low, with diversity maintained partly by source-sink dynamics
    corecore