47 research outputs found

    Competition and habitat quality influence age and sex distribution in wintering rusty blackbirds.

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    Bird habitat quality is often inferred from species abundance measures during the breeding and non-breeding season and used for conservation management decisions. However, during the non-breeding season age and sex classes often occupy different habitats which suggest a need for more habitat-specific data. Rusty Blackbird (Euphagus carolinus) is a forested wetland specialist wintering in bottomland hardwood forests in the south-eastern U. S. and belongs to the most steeply declining songbirds in the U.S. Little information is available to support priority birds such as the Rusty Blackbird wintering in this threatened habitat. We assessed age and sex distribution and body condition of Rusty Blackbirds among the three major habitats used by this species in the Lower Mississippi Alluvial Valley and also measured food availability. Overall, pecan groves had the highest biomass mainly driven by the amount of nuts. Invertebrate biomass was highest in forests but contributed only a small percentage to overall biomass. Age and sex classes were unevenly distributed among habitats with adult males primarily occupying pecan groves containing the highest nut biomass, females being found in forests which had the lowest nut biomass and young males primarily staying in forest fragments along creeks which had intermediate nut biomass. Males were in better body condition than females and were in slightly better condition in pecan groves. The results suggest that adult males occupy the highest quality habitat and may competitively exclude the other age and sex classes

    Expression of the progenitor marker NG2/CSPG4 predicts poor survival and resistance to ionising radiation in glioblastoma

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    Glioblastoma (GBM) is a highly aggressive brain tumour, where patients respond poorly to radiotherapy and exhibit dismal survival outcomes. The mechanisms of radioresistance are not completely understood. However, cancer cells with an immature stem-like phenotype are hypothesised to play a role in radioresistance. Since the progenitor marker neuron-glial-2 (NG2) has been shown to regulate several aspects of GBM progression in experimental systems, we hypothesised that its expression would influence the survival of GBM patients. Quantification of NG2 expression in 74 GBM biopsies from newly diagnosed and untreated patients revealed that 50% express high NG2 levels on tumour cells and associated vessels, being associated with significantly shorter survival. This effect was independent of age at diagnosis, treatment received and hypermethylation of the O6-methylguanine methyltransferase (MGMT) DNA repair gene promoter. NG2 was frequently co-expressed with nestin and vimentin but rarely with CD133 and the NG2 positive tumour cells harboured genetic aberrations typical for GBM. 2D proteomics of 11 randomly selected biopsies revealed upregulation of an antioxidant, peroxiredoxin-1 (PRDX-1), in the shortest surviving patients. Expression of PRDX-1 was associated with significantly reduced products of oxidative stress. Furthermore, NG2 expressing GBM cells showed resistance to ionising radiation (IR), rapidly recognised DNA damage and effectuated cell cycle checkpoint signalling. PRDX-1 knockdown transiently slowed tumour growth rates and sensitised them to IR in vivo. Our data establish NG2 as an important prognostic factor for GBM patient survival, by mediating resistance to radiotherapy through induction of ROS scavenging enzymes and preferential DNA damage signalling

    Projected sensitivities of the LUX-ZEPLIN experiment to new physics via low-energy electron recoils

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    LUX-ZEPLIN is a dark matter detector expected to obtain world-leading sensitivity to weakly-interacting massive particles interacting via nuclear recoils with a ∼ 7 -tonne xenon target mass. This paper presents sensitivity projections to several low-energy signals of the complementary electron recoil signal type: 1) an effective neutrino magnetic moment, and 2) an effective neutrino millicharge, both for p p -chain solar neutrinos, 3) an axion flux generated by the Sun, 4) axionlike particles forming the Galactic dark matter, 5) hidden photons, 6) mirror dark matter, and 7) leptophilic dark matter. World-leading sensitivities are expected in each case, a result of the large 5.6 t 1000 d exposure and low expected rate of electron-recoil backgrounds in the < 100     keV energy regime. A consistent signal generation, background model and profile-likelihood analysis framework is used throughout

    Projected sensitivity of the LUX-ZEPLIN experiment to the two-neutrino and neutrinoless double beta decays of Xe-134

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    Simulations of Events for the LUX-ZEPLIN (LZ) Dark Matter Experiment

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    The LUX-ZEPLIN dark matter search aims to achieve a sensitivity to the WIMP-nucleon spin-independent cross-section down to (1-2) ×\times 101210^{-12} pb at a WIMP mass of 40 GeV/c2c^2. This paper describes the simulations framework that, along with radioactivity measurements, was used to support this projection, and also to provide mock data for validating reconstruction and analysis software. Of particular note are the event generators, which allow us to model the background radiation, and the detector response physics used in the production of raw signals, which can be converted into digitized waveforms similar to data from the operational detector. Inclusion of the detector response allows us to process simulated data using the same analysis routines as developed to process the experimental data

    The LUX-ZEPLIN (LZ) Experiment

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    We describe the design and assembly of the LUX-ZEPLIN experiment, a direct detection search for cosmic WIMP dark matter particles. The centerpiece of the experiment is a large liquid xenon time projection chamber sensitive to low energy nuclear recoils. Rejection of backgrounds is enhanced by a Xe skin veto detector and by a liquid scintillator Outer Detector loaded with gadolinium for efficient neutron capture and tagging. LZ is located in the Davis Cavern at the 4850' level of the Sanford Underground Research Facility in Lead, South Dakota, USA. We describe the major subsystems of the experiment and its key design features and requirements

    Projected sensitivity of the LUX-ZEPLIN experiment to the 0νββ decay of 136Xe

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    The LUX-ZEPLIN (LZ) experiment will enable a neutrinoless double beta decay search in parallel to the main science goal of discovering dark matter particle interactions. We report the expected LZ sensitivity to ^136Xe neutrinoless double beta decay, taking advantage of the significant (>600 kg) ^136Xe mass contained within the active volume of LZ without isotopic enrichment. After 1000 live-days, the median exclusion sensitivity to the half-life of ^136Xe is projected to be 1.06×10^26 years (90% confidence level), similar to existing constraints. We also report the expected sensitivity of a possible subsequent dedicated exposure using 90% enrichment with ^136Xe at 1.06×10^27 years

    Projected sensitivity of the LUX-ZEPLIN experiment to the 0 ν β β decay of 136 Xe

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    The LUX-ZEPLIN (LZ) experiment will enable a neutrinoless double β decay search in parallel to the main science goal of discovering dark matter particle interactions. We report the expected LZ sensitivity to 136 Xe neutrinoless double β decay, taking advantage of the significant ( > 600 kg) 136 Xe mass contained within the active volume of LZ without isotopic enrichment. After 1000 live-days, the median exclusion sensitivity to the half-life of 136 Xe is projected to be 1.06 × 10 26 years (90% confidence level), similar to existing constraints. We also report the expected sensitivity of a possible subsequent dedicated exposure using 90% enrichment with 136 Xe at 1.06 × 10 27 years

    Projected sensitivities of the LUX-ZEPLIN (LZ) experiment to new physics via low-energy electron recoils

    Get PDF
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