570 research outputs found
Data Paper – High Resolution Vegetation Cover Data for the Southern Western Ghats of India. (IFP_ECODATA_VEGETATION)
This data paper has been prepared following the Ecological Metadata format proposed by Michener et al. (1997). It is accompanied with data archives downloadable from the IFP Biodiversity Portal at http://www.ifpindia.org/biodiversityportal/The Western Ghats form a 1,600 km long escarpment that runs parallel to the southwestern coast of Peninsular India. This relief barrier, which orographically exacerbates the summer monsoon rains, is responsible for steep bioclimatic gradients that have long been recognized as one of the major ecological determinants for the forest vegetation of the region. We report here girded vegetation data at 30' lat/long (ca. 1 km) resolution that cover an area of about 70,000 km2 of the southern Western Ghats, between 74 to 78° E and 8 to 16° N. These data have been extracted from: the 1:250,000 scale forest maps of South India published by the French Institute of Pondicherry (FIP), which have been digitized and simplified; the 2004 MODIS (Moderate Resolution Imaging Spectroradiometer) database, for the IGBP (International Biosphere Geosphere Programme) global vegetation Land Cover Type and Normalized Difference Vegetation Index (NDVI) of March 2004
Working conditions and risk exposure of employees whose occupations require driving on public roads - Factorial analysis and classification
Several studies of the working conditions of drivers, and in particular on their pace of work, have enabled a better understanding of the risk factors for road accidents that occur during work. However, few studies are available on the risk exposure and working conditions of employees whose occupations involve driving. The purpose of this paper is to identify the different groups of employees occupationally exposed to road risk and to classify them according to working conditions. Methodology A Multiple Correspondence Analysis (MCA) was implemented on the 41,727 individuals from the SUMER 2010 survey (Medical Monitoring of Occupational Risk Exposure: SUrveillance MĂ©dicale des Expositions aux Risques professionnels) and for 45 variables about working conditions. The analysis used 5 categories of weekly driving exposure as a supplementary variable (variable which is not used to perform the MCA): Non-exposure; Exposed 20?h. The results of the MCA were used to construct an ascending hierarchical classification. Results The first factorial axis differentiates between conventional and unconventional work schedules. Axis 2 differentiates modalities corresponding to the working hours of the most recent working week. The third axis chiefly contrasts persons who have rules to follow with those who have none. An ascending hierarchical classification distinguishes 10 clusters of individuals according to working conditions. Four clusters of employees were excessively exposed to occupational driving. Clusters also have distinct demographic, occupational and psychosocial characteristics. Conclusion Analysis of data from the SUMER survey confirms that employees exposed to road risk are particularly affected by atypical work time characteristics, but can be found in all activity sectors and in all types of job
Multi-mass solvers for lattice QCD on GPUs
Graphical Processing Units (GPUs) are more and more frequently used for
lattice QCD calculations. Lattice studies often require computing the quark
propagators for several masses. These systems can be solved using multi-shift
inverters but these algorithms are memory intensive which limits the size of
the problem that can be solved using GPUs. In this paper, we show how to
efficiently use a memory-lean single-mass inverter to solve multi-mass
problems. We focus on the BiCGstab algorithm for Wilson fermions and show that
the single-mass inverter not only requires less memory but also outperforms the
multi-shift variant by a factor of two.Comment: 27 pages, 6 figures, 3 Table
Stabilization of the cubic phase of HfO2 by Y addition in films grown by metal organic chemical vapor deposition
Addition of yttrium in HfO2 thin films prepared on silicon by metal organic chemical vapor deposition is investigated in a wide compositional range (2.0-99.5 at. %). The cubic structure of HfO2 is stabilized for 6.5 at. %. The permittivity is maximum for yttrium content of 6.5-10 at. %; in this range, the effective permittivity, which results from the contribution of both the cubic phase and silicate phase, is of 22. These films exhibit low leakage current density (5x10(-7) A/cm(2) at -1 V for a 6.4 nm film). The cubic phase is stable upon postdeposition high temperature annealing at 900 degrees C under NH3. (c) 2006 American Institute of Physics
K pi scattering for isospin 1/2 and 3/2 in lattice QCD
We simulate K pi scattering in s-wave and p-wave for both isospins I=1/2, 3/2
using quark-antiquark and meson-meson interpolating fields. We extract the
elastic phase shifts delta at several values of the K-pi relative momenta. The
resulting phases exhibit qualitative agreement with the experimental phases in
all four channels. We express the s-wave phase shifts near threshold in terms
of the scattering length and the effective range. Our K pi system has zero
total momentum and is simulated on a single ensemble with two dynamical quarks,
so results apply for mpi=266 MeV and mK=552 MeV in our simulation. The
backtracking contractions in both I=1/2 channels are handled by the use of
Laplacian-Heavyside smeared quarks within the distillation method. Elastic
phases are extracted from the energy levels using Luscher's relations. In all
four channels we observe the expected K(n)pi(-n) scattering states, which are
shifted due to the interaction. In both attractive I=1/2 channels we observe
additional states that are related to resonances; we attribute them to
K_0^*(1430) in s-wave and K*(892), K*(1410) and K*(1680) in p-wave.Comment: 17 pages, 7 figures, version published in PR
Impact of foot-and-mouth disease on mastitis and culling on a large-scale dairy farm in Kenya
Foot and mouth disease (FMD) is a highly transmissible viral infection of cloven hooved animals associated with severe economic losses when introduced into FMD-free countries. Information on the impact of the disease in FMDV-endemic countries is poorly characterised yet essential for the prioritisation of scarce resources for disease control programmes. A FMD (virus serotype SAT2) outbreak on a large-scale dairy farm in Nakuru County, Kenya provided an opportunity to evaluate the impact of FMD on clinical mastitis and culling rate. A cohort approach followed animals over a 12-month period after the commencement of the outbreak. For culling, all animals were included; for mastitis, those over 18 months of age. FMD was recorded in 400/644 cattle over a 29-day period. During the follow-up period 76 animals were culled or died whilst in the over 18 month old cohort 63 developed clinical mastitis. Hazard ratios (HR) were generated using Cox regression accounting for non-proportional hazards by inclusion of time-varying effects. Univariable analysis showed FMD cases were culled sooner but there was no effect on clinical mastitis. After adjusting for possible confounders and inclusion of time-varying effects there was weak evidence to support an effect of FMD on culling (HR = 1.7, 95% confidence intervals [CI] 0.88-3.1, P = 0.12). For mastitis, there was stronger evidence of an increased rate in the first month after the onset of the outbreak (HR = 2.9, 95%CI 0.97-8.9, P = 0.057)
Design and construction of a Cherenkov imager for charge measurement of nuclear cosmic rays
A proximity focusing Cherenkov imager called CHERCAM, has been built for the
charge measurement of nuclear cosmic rays with the CREAM instrument. It
consists of a silica aerogel radiator plane across from a detector plane
equipped with 1,600 1" diameter photomultipliers. The two planes are separated
by a ring expansion gap. The Cherenkov light yield is proportional to the
charge squared of the incident particle. The expected relative light collection
accuracy is in the few percents range. It leads to an expected single element
separation over the range of nuclear charge Z of main interest 1 < Z < 26.
CHERCAM is designed to fly with the CREAM balloon experiment. The design of the
instrument and the implemented technical solutions allowing its safe operation
in high altitude conditions (radiations, low pressure, cold) are presented.Comment: 24 pages, 19 figure
Recommended from our members
Impact of particles on the Planck HFI detectors: Ground-based measurements and physical interpretation
The Planck High Frequency Instrument (HFI) surveyed the sky continuously from
August 2009 to January 2012. Its noise and sensitivity performance were
excellent, but the rate of cosmic ray impacts on the HFI detectors was
unexpectedly high. Furthermore, collisions of cosmic rays with the focal plane
produced transient signals in the data (glitches) with a wide range of
characteristics. A study of cosmic ray impacts on the HFI detector modules has
been undertaken to categorize and characterize the glitches, to correct the HFI
time-ordered data, and understand the residual effects on Planck maps and data
products. This paper presents an evaluation of the physical origins of glitches
observed by the HFI detectors. In order to better understand the glitches
observed by HFI in flight, several ground-based experiments were conducted with
flight-spare HFI bolometer modules. The experiments were conducted between 2010
and 2013 with HFI test bolometers in different configurations using varying
particles and impact energies. The bolometer modules were exposed to 23 MeV
protons from the Orsay IPN TANDEM accelerator, and to Am and Cm
-particle and Fe radioactive X-ray sources. The calibration data
from the HFI ground-based preflight tests were used to further characterize the
glitches and compare glitch rates with statistical expectations under
laboratory conditions. Test results provide strong evidence that the dominant
family of glitches observed in flight are due to cosmic ray absorption by the
silicon die substrate on which the HFI detectors reside. Glitch energy is
propagated to the thermistor by ballistic phonons, while there is also a
thermal diffusion contribution. The implications of these results for future
satellite missions, especially those in the far-infrared to sub-millimetre and
millimetre regions of the electromagnetic spectrum, are discussed.Comment: 11 pages, 13 figure
Pattern and process in Amazon tree turnover, 1976-2001
Previous work has shown that tree turnover, tree biomass and large liana densities have increased in mature tropical forest plots in the late twentieth century. These results point to a concerted shift in forest ecological processes that may already be having significant impacts on terrestrial carbon stocks, fluxes and biodiversity. However, the findings have proved controversial, partly because a rather limited number of permanent plots have been monitored for rather short periods. The aim of this paper is to characterize regional-scale patterns of 'tree turnover' (the rate with which trees die and recruit into a population) by using improved datasets now available for Amazonia that span the past 25 years. Specifically, we assess whether concerted changes in turnover are occurring, and if so whether they are general throughout the Amazon or restricted to one region or environmental zone. In addition, we ask whether they are driven by changes in recruitment, mortality or both. We find that: (i) trees 10 cm or more in diameter recruit and die twice as fast on the richer soils of southern and western Amazonia than on the poorer soils of eastern and central Amazonia; (ii) turnover rates have increased throughout Amazonia over the past two decades; (iii) mortality and recruitment rates have both increased significantly in every region and environmental zone, with the exception of mortality in eastern Amazonia; (iv) recruitment rates have consistently exceeded mortality rates; (v) absolute increases in recruitment and mortality rates are greatest in western Amazonian sites; and (vi) mortality appears to be lagging recruitment at regional scales. These spatial patterns and temporal trends are not caused by obvious artefacts in the data or the analyses. The trends cannot be directly driven by a mortality driver (such as increased drought or fragmentation-related death) because the biomass in these forests has simultaneously increased. Our findings therefore indicate that long-acting and widespread environmental changes are stimulating the growth and productivity of Amazon forests
Improved annotation of 3' untranslated regions and complex loci by combination of strand-specific direct RNA sequencing, RNA-seq and ESTs
The reference annotations made for a genome sequence provide the framework
for all subsequent analyses of the genome. Correct annotation is particularly
important when interpreting the results of RNA-seq experiments where short
sequence reads are mapped against the genome and assigned to genes according to
the annotation. Inconsistencies in annotations between the reference and the
experimental system can lead to incorrect interpretation of the effect on RNA
expression of an experimental treatment or mutation in the system under study.
Until recently, the genome-wide annotation of 3-prime untranslated regions
received less attention than coding regions and the delineation of intron/exon
boundaries. In this paper, data produced for samples in Human, Chicken and A.
thaliana by the novel single-molecule, strand-specific, Direct RNA Sequencing
technology from Helicos Biosciences which locates 3-prime polyadenylation sites
to within +/- 2 nt, were combined with archival EST and RNA-Seq data. Nine
examples are illustrated where this combination of data allowed: (1) gene and
3-prime UTR re-annotation (including extension of one 3-prime UTR by 5.9 kb);
(2) disentangling of gene expression in complex regions; (3) clearer
interpretation of small RNA expression and (4) identification of novel genes.
While the specific examples displayed here may become obsolete as genome
sequences and their annotations are refined, the principles laid out in this
paper will be of general use both to those annotating genomes and those seeking
to interpret existing publically available annotations in the context of their
own experimental dataComment: 44 pages, 9 figure
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