103 research outputs found

    Hierarchical Bayesian variable selection in the probit model with mixture of nominal and ordinal responses

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    Multi-class classification problems have been studied for pure nominal and pure ordinal responses. However, there are some cases where the multi-class responses are a mixture of nominal and ordinal. To address this problem we build a hierarchical multinomial probit model with a mixture of both types of responses using latent variables. The nominal responses are each associated to distinct latent variables whereas the ordinal responses have a single latent variable. Our approach first treats the ordinal responses as a single nominal category and then separates the ordinal responses within this category. We introduce sparsity into the model using Bayesian variable selection (BVS) within the regression in order to improve variable selection classification accuracy. Two indicator vectors (indicating presence of the covariate) are used, one for nominal and one for ordinal responses. We develop efficient posteriorsampling. Using simulated data, we compare the classification accuracy of our method to existing ones

    Radon measurements along active faults in the Langadas Basin, northern Greece

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    A network of three radon stations has been established in the Langadas Basin, northern Greece for radon monitoring by various techniques in earthquake prediction studies. Specially made devices with plastic tubes including Alpha Tracketch Detectors (ATD) were installed for registering alpha particles from radon and radon decay products exhaled from the ground, every 2 weeks, by using LR-115, type II, non-strippable Kodak films, starting from December 1996. Simultaneous measurements started using Lucas cells alpha spectrometer for instantaneous radon measurements in soil gas, before and after setting ATDs at the radon stations. Continuous monitoring of radon gas exhaling from the ground started from the middle of August 1999 by using silicon diode detectors, which simultaneously register meteorological parameters, such as rainfall, temperature and barometric pressure. The obtained data were studied together with the data of seismic events, such as the magnitude, <i>M<sub>L</sub></i>, of earthquakes that occurred at the Langadas Basin during the period of measurements, as registered by the Laboratory of Geophysics, Aristotle University of Thessaloniki, in order to find out any association between them

    Radon measurements along active faults in the Langadas Basin, northern Greece

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    Radon measurements in association with earthquakes

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    A network of three radon stations has been established in the Langadas basin, North Greece. Newly made devices with plastic tubes are in operation with a-particle track detectors (ATDs) in registering a-particles from radon and radon decay products exhaled from the ground, every two weeks, starting from December 1996, by using LR-115, type II, nonstrippable Kodak films. Simultaneous measurements are made by using Lucas a-scintillation cells for instantaneous measurements of radon in soil gas, before and after setting the ATDs at the radon stations. The new devices used have the advantage of not using heating systems nor electrical power in the nearby area of the stations. Radon flux registrations ranged between 507 and 85880 tr cm22 or 1.5 and 188.9 tr cm22 h21, in the period of measurement, while radon concentrations in soil gas ranged between 528 and 35095 Bq m23 at the same time

    Radionuclide Analysis on Bamboos following the Fukushima Nuclear Accident

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    In response to contamination from the recent Fukushima nuclear accident, we conducted radionuclide analysis on bamboos sampled from six sites within a 25 to 980 km radius of the Fukushima Daiichi nuclear power plant. Maximum activity concentrations of radiocesium 134Cs and 137Cs in samples from Fukushima city, 65 km away from the Fukushima Daiichi plant, were in excess of 71 and 79 kBq/kg, dry weight (DW), respectively. In Kashiwa city, 195 km away from the Fukushima Daiichi, the sample concentrations were in excess of 3.4 and 4.3 kBq/kg DW, respectively. In Toyohashi city, 440 km away from the Fukushima Daiichi, the concentrations were below the measurable limits of up to 4.5 Bq/kg DW. In the radiocesium contaminated samples, the radiocesium activity was higher in mature and fallen leaves than in young leaves, branches and culms

    Designed Inhibitors of Insulin-Degrading Enzyme Regulate the Catabolism and Activity of Insulin

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    Background: Insulin is a vital peptide hormone that is a central regulator of glucose homeostasis, and impairments in insulin signaling cause diabetes mellitus. In principle, it should be possible to enhance the activity of insulin by inhibiting its catabolism, which is mediated primarily by insulin-degrading enzyme (IDE), a structurally and evolutionarily distinctive zinc-metalloprotease. Despite interest in pharmacological inhibition of IDE as an attractive anti-diabetic approach dating to the 1950s, potent and selective inhibitors of IDE have not yet emerged. Methodology/Principal Findings: We used a rational design approach based on analysis of combinatorial peptide mixtures and focused compound libraries to develop novel peptide hydroxamic acid inhibitors of IDE. The resulting compounds are ∼106 times more potent than existing inhibitors, non-toxic, and surprisingly selective for IDE vis-à-vis conventional zinc-metalloproteases. Crystallographic analysis of an IDE-inhibitor complex reveals a novel mode of inhibition based on stabilization of IDE's “closed,” inactive conformation. We show further that pharmacological inhibition of IDE potentiates insulin signaling by a mechanism involving reduced catabolism of internalized insulin. Conclusions/Significance: The inhibitors we describe are the first to potently and selectively inhibit IDE or indeed any member of this atypical zinc-metalloprotease superfamily. The distinctive structure of IDE's active site, and the mode of action of our inhibitors, suggests that it may be possible to develop inhibitors that cross-react minimally with conventional zinc-metalloproteases. Significantly, our results reveal that insulin signaling is normally regulated by IDE activity not only extracellularly but also within cells, supporting the longstanding view that IDE inhibitors could hold therapeutic value for the treatment of diabetes

    Eco-friendly one-pot synthesis of Prussian blue-embedded magnetic hydrogel beads for the removal of cesium from water

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    A simple one-step approach to fabricating Prussian blue-embedded magnetic hydrogel beads (PBMHBs) was fabricated for the effective magnetic removal of radioactive cesium (Cs-137) from water. Through the simple dropwise addition of a mixed aqueous solution of iron salts, commercial PB and polyvinyl alcohol (PVA) to an ammonium hydroxide (NH4OH) solution, the formation of hydrogel beads and the encapsulation of PB in beads were achieved in one pot through the gelation of PVA with in situ-formed iron oxide nanoparticles as the cross-linker. The obtained PB-MHBs, with 43.77 weight %of PB, were stable without releasing PB for up to 2 weeks and could be effectively separated from aqueous solutions by an external magnetic field, which is convenient for the large-scale treatment of Cs-contaminated water. Detailed Cs adsorption studies revealed that the adsorption isotherms and kinetics could be effectively described by the Langmuir isotherm model and the pseudo-second-order model, respectively. Most importantly, the PB-MHBs exhibited excellent selectivity for Cs-137 in (137)Cscontaminated simulated groundwater (55 Bq/g) with a high removal efficiency (&gt;99.5%), and the effective removal of Cs-137 from real seawater by these PB-MHBs demonstrated the excellent potential of this material for practical application in the decontamination of Cs-137-contaminated seawate

    The XMM Cluster Survey: New evidence for the 3.5-keV feature in clusters is inconsistent with a dark matter origin

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    There have been several reports of a detection of an unexplained excess of X-ray emission at \simeq3.5 keV in astrophysical systems. One interpretation of this excess is the decay of sterile neutrino dark matter. The most influential study to date analysed 73 clusters observed by the XMM-Newton satellite. We explore evidence for a â 3.5-keV excess in the XMM-PN spectra of 117 redMaPPer galaxy clusters (0.1 < z < 0.6). In our analysis of individual spectra, we identify three systems with an excess of flux at \simeq3.5 keV. In one case (XCS J0003.3+0204), this excess may result from a discrete emission line. None of these systems are the most dark matter dominated in our sample. We group the remaining 114 clusters into four temperature (TX) bins to search for an increase in â 3.5-keV flux excess with TX-a reliable tracer of halo mass. However, we do not find evidence of a significant excess in flux at â 3.5 keV in any TX bins. To maximize sensitivity to a potentially weak dark matter decay feature at â 3.5 keV, we jointly fit 114 clusters. Again, no significant excess is found at â 3.5 keV. We estimate the upper limit of an undetected emission line at â 3.5 keV to be 2.41 × 10-6 photons cm-2 s-1, corresponding to a mixing angle of sin 2(2θ) = 4.4 × 10-11, lower than previous estimates from cluster studies. We conclude that a flux excess at â 3.5 keV is not a ubiquitous feature in clusters and therefore unlikely to originate from sterile neutrino dark matter decay. © 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
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