138 research outputs found
Air pollution modelling using a graphics processing unit with CUDA
The Graphics Processing Unit (GPU) is a powerful tool for parallel computing.
In the past years the performance and capabilities of GPUs have increased, and
the Compute Unified Device Architecture (CUDA) - a parallel computing
architecture - has been developed by NVIDIA to utilize this performance in
general purpose computations. Here we show for the first time a possible
application of GPU for environmental studies serving as a basement for decision
making strategies. A stochastic Lagrangian particle model has been developed on
CUDA to estimate the transport and the transformation of the radionuclides from
a single point source during an accidental release. Our results show that
parallel implementation achieves typical acceleration values in the order of
80-120 times compared to CPU using a single-threaded implementation on a 2.33
GHz desktop computer. Only very small differences have been found between the
results obtained from GPU and CPU simulations, which are comparable with the
effect of stochastic transport phenomena in atmosphere. The relatively high
speedup with no additional costs to maintain this parallel architecture could
result in a wide usage of GPU for diversified environmental applications in the
near future.Comment: 5 figure
Adinkras From Ordered Quartets of BC Coxeter Group Elements and Regarding 1,358,954,496 Matrix Elements of the Gadget
We examine values of the Adinkra Holoraumy-induced Gadget representation
space metric over all possible four-color, four-open node, and four-closed node
adinkras. Of the 1,358,954,496 gadget matrix elements, only 226,492,416 are
non-vanishing and take on one of three values: , , or and thus a
subspace isomorphic to a description of a body-centered tetrahedral molecule
emerges.Comment: LaTeX twice, 56pp, 30 tables, 5 figures, latest version includes link
to updated code, minor corrections, and additional support about inequivalent
representations and tetrahedral geometry comments added along with
observations about similarity with results previously found by Nekraso
Gravitational collapse of a Hagedorn fluid in Vaidya geometry
The gravitational collapse of a high-density null charged matter fluid,
satisfying the Hagedorn equation of state, is considered in the framework of
the Vaidya geometry. The general solution of the gravitational field equations
can be obtained in an exact parametric form. The conditions for the formation
of a naked singularity, as a result of the collapse of the compact object, are
also investigated. For an appropriate choice of the arbitrary integration
functions the null radial outgoing geodesic, originating from the shell
focussing central singularity, admits one or more positive roots. Hence a
collapsing Hagedorn fluid could end either as a black hole, or as a naked
singularity. A possible astrophysical application of the model, to describe the
energy source of gamma-ray bursts, is also considered.Comment: 14 pages, 2 figures, to appear in Phys. Rev.
Weak reaction freeze-out constraints on primordial magnetic fields
We explore constraints on the strength of the primordial magnetic field based
upon the weak reaction freeze-out in the early universe. We find that limits on
the strength of the magnetic field found in other works are recovered simply by
examining the temperature at which the rate of weak reactions drops below the
rate of universal expansion ( H). The temperature for which the
ratio at freeze-out leads to acceptable helium production implies limits
on the magnetic field. This simplifies the application of magnetic fields to
other cosmological variants of the standard big-bang. As an illustration we
also consider effects of neutrino degeneracy on the allowed limits to the
primordial magnetic field.Comment: Submitted to Phys. Rev. D., 6 pages, 2 figure
Discrete molecular dynamics can predict helical prestructured motifs in disordered proteins.
Intrinsically disordered proteins (IDPs) lack a stable tertiary structure, but their short binding regions termed Pre-Structured Motifs (PreSMo) can form transient secondary structure elements in solution. Although disordered proteins are crucial in many biological processes and designing strategies to modulate their function is highly important, both experimental and computational tools to describe their conformational ensembles and the initial steps of folding are sparse. Here we report that discrete molecular dynamics (DMD) simulations combined with replica exchange (RX) method efficiently samples the conformational space and detects regions populating alpha-helical conformational states in disordered protein regions. While the available computational methods predict secondary structural propensities in IDPs based on the observation of protein-protein interactions, our ab initio method rests on physical principles of protein folding and dynamics. We show that RX-DMD predicts alpha-PreSMos with high confidence confirmed by comparison to experimental NMR data. Moreover, the method also can dissect alpha-PreSMos in close vicinity to each other and indicate helix stability. Importantly, simulations with disordered regions forming helices in X-ray structures of complexes indicate that a preformed helix is frequently the binding element itself, while in other cases it may have a role in initiating the binding process. Our results indicate that RX-DMD provides a breakthrough in the structural and dynamical characterization of disordered proteins by generating the structural ensembles of IDPs even when experimental data are not available
Parents' perceived vulnerability and perceived control in preventing Meningococcal C infection: a large-scale interview study about vaccination
<p>Abstract</p> <p>Background</p> <p>Parents' reported ambivalence toward large-scale vaccination programs for childhood diseases may be related to their perception of the risks of side-effects or safety of vaccination and the risk of contracting the disease. The aim of this study is to evaluate parents' perceptions of their child's risk contracting a Meningococcal C infection and parents' perceived control in preventing infection in relation to their evaluation of the safety, effectiveness and usefulness of vaccination.</p> <p>Methods</p> <p>In a large-scale interview study, a random sample of parents was interviewed after their children had received vaccination against Meningococcal C in a catch-up campaign. Questions were asked about the perceived relative vulnerability of their child contracting an infection, perceived control in preventing an infection, and parents' evaluation of the safety, usefulness and effectiveness of vaccination.</p> <p>Results</p> <p>61% of 2910 (N = 1763) parents who were approached participated. A higher perceived relative vulnerability of their own child contracting the disease was related to a more positive evaluation of the vaccination campaign, while a lower perceived vulnerability did not result in a more negative evaluation. A higher perceived control in being able to prevent an infection was, however, related to a more critical attitude toward the safety, usefulness and effectiveness of vaccination.</p> <p>Conclusion</p> <p>Perceived relative vulnerability contracting an infection and parents' perceived control in preventing an infection seem to influence parents' evaluation of the vaccination programme. Future studies should determine if, and under which circumstances, these perceptions also affect parents' vaccination behaviour and would be relevant to be taken into account when educating parents about vaccination.</p
Gαi2- and Gαi3-Specific Regulation of Voltage-Dependent L-Type Calcium Channels in Cardiomyocytes
BACKGROUND: Two pertussis toxin sensitive G(i) proteins, G(i2) and G(i3), are expressed in cardiomyocytes and upregulated in heart failure. It has been proposed that the highly homologous G(i) isoforms are functionally distinct. To test for isoform-specific functions of G(i) proteins, we examined their role in the regulation of cardiac L-type voltage-dependent calcium channels (L-VDCC). METHODS: Ventricular tissues and isolated myocytes were obtained from mice with targeted deletion of either Gα(i2) (Gα(i2) (-/-)) or Gα(i3) (Gα(i3) (-/-)). mRNA levels of Gα(i/o) isoforms and L-VDCC subunits were quantified by real-time PCR. Gα(i) and Ca(v)α(1) protein levels as well as protein kinase B/Akt and extracellular signal-regulated kinases 1/2 (ERK1/2) phosphorylation levels were assessed by immunoblot analysis. L-VDCC function was assessed by whole-cell and single-channel current recordings. RESULTS: In cardiac tissue from Gα(i2) (-/-) mice, Gα(i3) mRNA and protein expression was upregulated to 187 ± 21% and 567 ± 59%, respectively. In Gα(i3) (-/-) mouse hearts, Gα(i2) mRNA (127 ± 5%) and protein (131 ± 10%) levels were slightly enhanced. Interestingly, L-VDCC current density in cardiomyocytes from Gα(i2) (-/-) mice was lowered (-7.9 ± 0.6 pA/pF, n = 11, p<0.05) compared to wild-type cells (-10.7 ± 0.5 pA/pF, n = 22), whereas it was increased in myocytes from Gα(i3) (-/-) mice (-14.3 ± 0.8 pA/pF, n = 14, p<0.05). Steady-state inactivation was shifted to negative potentials, and recovery kinetics slowed in the absence of Gα(i2) (but not of Gα(i3)) and following treatment with pertussis toxin in Gα(i3) (-/-). The pore forming Ca(v)α(1) protein level was unchanged in all mouse models analyzed, similar to mRNA levels of Ca(v)α(1) and Ca(v)β(2) subunits. Interestingly, at the cellular signalling level, phosphorylation assays revealed abolished carbachol-triggered activation of ERK1/2 in mice lacking Gα(i2). CONCLUSION: Our data provide novel evidence for an isoform-specific modulation of L-VDCC by Gα(i) proteins. In particular, loss of Gα(i2) is reflected by alterations in channel kinetics and likely involves an impairment of the ERK1/2 signalling pathway
The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment
The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in
operation since July 2014. This paper describes the second data release from
this phase, and the fourteenth from SDSS overall (making this, Data Release
Fourteen or DR14). This release makes public data taken by SDSS-IV in its first
two years of operation (July 2014-2016). Like all previous SDSS releases, DR14
is cumulative, including the most recent reductions and calibrations of all
data taken by SDSS since the first phase began operations in 2000. New in DR14
is the first public release of data from the extended Baryon Oscillation
Spectroscopic Survey (eBOSS); the first data from the second phase of the
Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2),
including stellar parameter estimates from an innovative data driven machine
learning algorithm known as "The Cannon"; and almost twice as many data cubes
from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous
release (N = 2812 in total). This paper describes the location and format of
the publicly available data from SDSS-IV surveys. We provide references to the
important technical papers describing how these data have been taken (both
targeting and observation details) and processed for scientific use. The SDSS
website (www.sdss.org) has been updated for this release, and provides links to
data downloads, as well as tutorials and examples of data use. SDSS-IV is
planning to continue to collect astronomical data until 2020, and will be
followed by SDSS-V.Comment: SDSS-IV collaboration alphabetical author data release paper. DR14
happened on 31st July 2017. 19 pages, 5 figures. Accepted by ApJS on 28th Nov
2017 (this is the "post-print" and "post-proofs" version; minor corrections
only from v1, and most of errors found in proofs corrected
TRY plant trait database - enhanced coverage and open access
Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives
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