305 research outputs found
The Atapuerca sites and the Ibeas hominids
The Atapuerca railway Trench and Ibeas sites near Burgos, Spain,
are cave fillings that include a series of deposits ranging from
below the Matuyama/Bruhnes reversal up to the end of Middle
Pleistocene. The lowest fossil-bearing bed in the Trench contains
an assemblage of large and small Mammals including Mimomys
savini, Pitymys gregaloides, Pliomys episcopalis, Crocuta crocuta,
Dama sp. and Megacerini; the uppermost assemblage includes
Canis lupus, Lynx spelaea, Panthera (Leo) fossilis, Felis sylvestris,
Equus caballus steinheimensis, E.c. germanicus, Pitymys subtenaneus,
Microtus arvalis agrestis, Pliomys lenki, and also Panthera
toscana, Dicerorhinus bemitoechus, Bison schoetensacki, which are
equally present in the lowest level. The biostratigraphic correlation
and dates of the sites are briefly discussed, as are the
paleoclimatic interpretation of the Trench sequences. Stone artifacts
are found in several layers; the earliest occurrences correspond
to the upper beds containing Mimomys savini. A set of
preserved human occupation floors has been excavated in the top
fossil-bearing beds. The stone-tool assemblages of the upper levels
are of upper-medial Acheulean to Charentian tradition. The rich
bone breccia SH, in the Cueva Mayor-Cueva del Silo, Ibeas de
Juarros, is a derived deposit, due to a mud flow that dispersed and
carried the skeletons of many carnivores and humans. The taxa
represented are: Vrsus deningeri (largely dominant), Panthera (Leo)
fossilis, Vulpes vulpes, Homo sapiens var. Several traits of both
mandibular and cranial remains are summarized. Preliminary attempts
at dating suggest that the Ibeas fossil man is older than the
Last Interglacial, or oxygen-isotope stage 5
Anisotropy and chemical composition of ultra-high energy cosmic rays using arrival directions measured by the Pierre Auger Observatory
The Pierre Auger Collaboration has reported evidence for anisotropy in the
distribution of arrival directions of the cosmic rays with energies
eV. These show a correlation with the distribution
of nearby extragalactic objects, including an apparent excess around the
direction of Centaurus A. If the particles responsible for these excesses at
are heavy nuclei with charge , the proton component of the
sources should lead to excesses in the same regions at energies . We here
report the lack of anisotropies in these directions at energies above
(for illustrative values of ). If the anisotropies
above are due to nuclei with charge , and under reasonable
assumptions about the acceleration process, these observations imply stringent
constraints on the allowed proton fraction at the lower energies
A genome-wide association study follow-up suggests a possible role for PPARG in systemic sclerosis susceptibility
Introduction:
A recent genome-wide association study (GWAS) comprising a French cohort of systemic sclerosis (SSc) reported several non-HLA single-nucleotide polymorphisms (SNPs) showing a nominal association in the discovery phase. We aimed to identify previously overlooked susceptibility variants by using a follow-up strategy.<p></p>
Methods:
Sixty-six non-HLA SNPs showing a P value <10-4 in the discovery phase of the French SSc GWAS were analyzed in the first step of this study, performing a meta-analysis that combined data from the two published SSc GWASs. A total of 2,921 SSc patients and 6,963 healthy controls were included in this first phase. Two SNPs, PPARG rs310746 and CHRNA9 rs6832151, were selected for genotyping in the replication cohort (1,068 SSc patients and 6,762 healthy controls) based on the results of the first step. Genotyping was performed by using TaqMan SNP genotyping assays.
Results:
We observed nominal associations for both PPARG rs310746 (PMHâ=â1.90âĂâ10-6, OR, 1.28) and CHRNA9 rs6832151 (PMHâ=â4.30âĂâ10-6, OR, 1.17) genetic variants with SSc in the first step of our study. In the replication phase, we observed a trend of association for PPARG rs310746 (P valueâ=â0.066; OR, 1.17). The combined overall Mantel-Haenszel meta-analysis of all the cohorts included in the present study revealed that PPARG rs310746 remained associated with SSc with a nominal non-genome-wide significant P value (PMHâ=â5.00âĂâ10-7; OR, 1.25). No evidence of association was observed for CHRNA9 rs6832151 either in the replication phase or in the overall pooled analysis.<p></p>
Conclusion:
Our results suggest a role of PPARG gene in the development of SSc
Update on the correlation of the highest energy cosmic rays with nearby extragalactic matter
Data collected by the Pierre Auger Observatory through 31 August 2007 showed
evidence for anisotropy in the arrival directions of cosmic rays above the
Greisen-Zatsepin-Kuz'min energy threshold, \nobreak{eV}. The
anisotropy was measured by the fraction of arrival directions that are less
than from the position of an active galactic nucleus within 75 Mpc
(using the V\'eron-Cetty and V\'eron catalog). An updated
measurement of this fraction is reported here using the arrival directions of
cosmic rays recorded above the same energy threshold through 31 December 2009.
The number of arrival directions has increased from 27 to 69, allowing a more
precise measurement. The correlating fraction is , compared
with expected for isotropic cosmic rays. This is down from the early
estimate of . The enlarged set of arrival directions is
examined also in relation to other populations of nearby extragalactic objects:
galaxies in the 2 Microns All Sky Survey and active galactic nuclei detected in
hard X-rays by the Swift Burst Alert Telescope. A celestial region around the
position of the radiogalaxy Cen A has the largest excess of arrival directions
relative to isotropic expectations. The 2-point autocorrelation function is
shown for the enlarged set of arrival directions and compared to the isotropic
expectation.Comment: Accepted for publication in Astroparticle Physics on 31 August 201
The Fluorescence Detector of the Pierre Auger Observatory
The Pierre Auger Observatory is a hybrid detector for ultra-high energy
cosmic rays. It combines a surface array to measure secondary particles at
ground level together with a fluorescence detector to measure the development
of air showers in the atmosphere above the array. The fluorescence detector
comprises 24 large telescopes specialized for measuring the nitrogen
fluorescence caused by charged particles of cosmic ray air showers. In this
paper we describe the components of the fluorescence detector including its
optical system, the design of the camera, the electronics, and the systems for
relative and absolute calibration. We also discuss the operation and the
monitoring of the detector. Finally, we evaluate the detector performance and
precision of shower reconstructions.Comment: 53 pages. Submitted to Nuclear Instruments and Methods in Physics
Research Section
Search for First Harmonic Modulation in the Right Ascension Distribution of Cosmic Rays Detected at the Pierre Auger Observatory
We present the results of searches for dipolar-type anisotropies in different
energy ranges above eV with the surface detector array of
the Pierre Auger Observatory, reporting on both the phase and the amplitude
measurements of the first harmonic modulation in the right-ascension
distribution. Upper limits on the amplitudes are obtained, which provide the
most stringent bounds at present, being below 2% at 99% for EeV
energies. We also compare our results to those of previous experiments as well
as with some theoretical expectations.Comment: 28 pages, 11 figure
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