3,013 research outputs found
The homestake surface-underground scintillations: Description
Two new detectors are currently under construction at the Homestake Gold Mine a 140-ton Large Area Scintillation Detector (LASD) with an upper surface area of 130 square meters, a geometry factor (for an isotropic flux) of 1200 square meters, sr, and a depth of 4200 m.w.e.; and a surface air shower array consisting of 100 scintillator elements, each 3 square meters, spanning an area of approximately square kilometers. Underground, half of the LASD is currently running and collecting muon data; on the surface, the first section of the air shower array will begin operation in the spring of 1985. The detectors and their capabilities are described
Eucalyptus largiflorens F. Muell.
https://thekeep.eiu.edu/herbarium_specimens_byname/9502/thumbnail.jp
Eucalyptus largiflorens F. Muell.
https://thekeep.eiu.edu/herbarium_specimens_byname/9502/thumbnail.jp
Using MODIS estimates of fractional snow cover area to improve streamflow forecasts in interior Alaska
Remotely sensed snow cover observations provide an
opportunity to improve operational snowmelt and streamflow forecasting in
remote regions. This is particularly true in Alaska, where remote basins and
a spatially and temporally sparse gaging network plague efforts to
understand and forecast the hydrology of subarctic boreal basins and where
climate change is leading to rapid shifts in basin function. In this study,
the operational framework employed by the United States (US) National
Weather Service, including the Alaska Pacific River Forecast Center, is
adapted to integrate Moderate Resolution Imaging Spectroradiometer (MODIS)
remotely sensed observations of fractional snow cover area (fSCA) to
determine if these data improve streamflow forecasts in interior Alaska
river basins. Two versions of MODIS fSCA are tested against a base case
extent of snow cover derived by aerial depletion curves: the MODIS 10A1
(MOD10A1) and the MODIS Snow Cover Area and Grain size (MODSCAG) product
over the period 2000–2010. Observed runoff is compared to simulated runoff
to calibrate both iterations of the model. MODIS-forced simulations have
improved snow depletion timing compared with snow telemetry sites in the
basins, with discernable increases in skill for the streamflow simulations.
The MODSCAG fSCA version provides moderate increases in skill but is similar
to the MOD10A1 results. The basins with the largest improvement in
streamflow simulations have the sparsest streamflow observations.
Considering the numerous low-quality gages (discontinuous, short, or
unreliable) and ungauged systems throughout the high-latitude regions of the
globe, this result is valuable and indicates the utility of the MODIS fSCA
data in these regions. Additionally, while improvements in predicted
discharge values are subtle, the snow model better represents the physical
conditions of the snowpack and therefore provides more robust simulations,
which are consistent with the US National Weather Service's move toward a
physically based National Water Model. Physically based models may also be
more capable of adapting to changing climates than statistical models
corrected to past regimes. This work provides direction for both the Alaska
Pacific River Forecast Center and other forecast centers across the US to
implement remote-sensing observations within their operational framework, to
refine the representation of snow, and to improve streamflow forecasting
skill in basins with few or poor-quality observations.</p
GPR55 deficiency is associated with increased adiposity and impaired insulin signaling in peripheral metabolic tissues
This work was supported by the Biotechnology and Biological Sciences Research Council (BBSRC) and Diabetes UK. The authors declare no conflicts of interest. This article includes supplemental data. Please visit http://www.fasebj.org to obtain this information.Peer reviewedPublisher PD
Low energy excitations in crystalline perovskite oxides: Evidence from noise experiments
In this paper we report measurements of 1/f noise in a crystalline metallic
oxide with perovskite structure down to 4.2K. The results show existence of
localized excitations with average activation energy 70-80 meV which
produce peak in the noise at T 35-40K. In addition, it shows clear
evidence of tunnelling type two-level-systems (as in glasses) which show up in
noise measurements below 30K.Comment: 11 pages, 4 figures, to appear in Phys Rev B, vol 58, 1st Dec issu
Using airborne LiDAR Survey to explore historic-era archaeological landscapes of Montserrat in the eastern Caribbean
This article describes what appears to be the first archaeological application of airborne LiDAR survey to historic-era landscapes in the Caribbean archipelago, on the island of Montserrat. LiDAR is proving invaluable in extending the reach of traditional pedestrian survey into less favorable areas, such as those covered by dense neotropical forest and by ashfall from the past two decades of active eruptions by the Soufrière Hills volcano, and to sites in localities that are inaccessible on account of volcanic dangers. Emphasis is placed on two aspects of the research: first, the importance of ongoing, real-time interaction between the LiDAR analyst and the archaeological team in the field; and second, the advantages of exploiting the full potential of the three-dimensional LiDAR point cloud data for purposes of the visualization of archaeological sites and features
Hydrophobic and Charged Residues in the C-Terminal Arm of Hepatitis C Virus RNA-Dependent RNA Polymerase Regulate Initiation and Elongation.
The RNA-dependent RNA polymerase (RdRp) of hepatitis C virus (HCV) is essential for viral genome replication. Crystal structures of the HCV RdRp reveal two C-terminal features, a β-loop and a C-terminal arm, suitably located for involvement in positioning components of the initiation complex. Here we show that these two elements intimately regulate template and nucleotide binding, initiation, and elongation. We constructed a series of β-loop and C-terminal arm mutants, which were used for in vitro analysis of RdRp de novo initiation and primer extension activities. All mutants showed a substantial decrease in initiation activities but a marked increase in primer extension activities, indicating an ability to form more stable elongation complexes with long primer-template RNAs. Structural studies of the mutants indicated that these enzyme properties might be attributed to an increased flexibility in the C-terminal features resulting in a more open polymerase cleft, which likely favors the elongation process but hampers the initiation steps. A UTP cocrystal structure of one mutant shows, in contrast to the wild-type protein, several alternate conformations of the substrate, confirming that even subtle changes in the C-terminal arm result in a more loosely organized active site and flexible binding modes of the nucleotide. We used a subgenomic replicon system to assess the effects of the same mutations on viral replication in cells. Even the subtlest mutations either severely impaired or completely abolished the ability of the replicon to replicate, further supporting the concept that the correct positioning of both the β-loop and C-terminal arm plays an essential role during initiation and in HCV replication in general.
IMPORTANCE:
HCV RNA polymerase is a key target for the development of directly acting agents to cure HCV infections, which necessitates a thorough understanding of the functional roles of the various structural features of the RdRp. Here we show that even highly conservative changes, e.g., Tyr→Phe or Asp→Glu, in these seemingly peripheral structural features have profound effects on the initiation and elongation properties of the HCV polymerase
Charged particle production in the Pb+Pb system at 158 GeV/c per nucleon
Charged particle multiplicities from high multiplicity central interactions
of 158 GeV/nucleon Pb ions with Pb target nuclei have been measured in the
central and far forward projectile spectator regions using emulsion chambers.
Multiplicities are significantly lower than predicted by Monte Carlo
simulations. We examine the shape of the pseudorapidity distribution and its
dependence on centrality in detail.Comment: 17 pages text plus 12 figures in postscript 12/23/99 -- Add TeX
version of sourc
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