269 research outputs found
The LOFT Burst Alert System and its Burst On-board Trigger
The ESA M3 candidate mission LOFT (Large Observatory For x-ray Timing) has
been designed to study strong gravitational fields by observing compact
objects, such as black-hole binaries or neutron-star systems and supermassive
black-holes, based on the temporal analysis of photons collected by the primary
instrument LAD (Large Area Detector), sensitive to X-rays from 2 to 50 keV,
offering a very large effective area (>10 m 2 ), but a small field of view
({\o}<1{\deg}). Simultaneously the second instrument WFM (Wide Field Monitor),
composed of 5 coded-mask camera pairs (2-50 keV), monitors a large part of the
sky, in order to detect and localize eruptive sources, to be observed with the
LAD after ground-commanded satellite repointing. With its large field of view
(>{\pi} sr), the WFM actually detects all types of transient sources, including
Gamma-Ray Bursts (GRBs), which are of primary interest for a world-wide
observers community. However, observing the quickly decaying GRB afterglows
with ground-based telescopes needs the rapid knowledge of their precise
localization. The task of the Loft Burst Alert System (LBAS) is therefore to
detect in near- real-time GRBs (about 120 detections expected per year) and
other transient sources, and to deliver their localization in less than 30
seconds to the observers, via a VHF antenna network. Real-time full resolution
data download to ground being impossible, the real-time data processing is
performed onboard by the LBOT (LOFT Burst On-board Trigger system). In this
article we present the LBAS and its components, the LBOT and the associated
ground-segment.Comment: Proc. SPIE 9144, Space Telescopes and Instrumentation 2014:
Ultraviolet to Gamma Ray, 91446
Identifying the optimal landscape configuration for landscape multifunctionality
Increased pressure on land resources to provide multiple benefits calls for landscape strategies that optimize the supply of multiple ecosystem services (ES). Previous research into the drivers of landscape multifunctionality have focused on land use composition changes, but the spatial configuration of different land use types also drives ES supply. While the impact of landscape configuration on individual ES is well understood, the net outcome of these influences when considering many ES is not. Here we present the net-balance spatial interactions hypothesis, which posits that the strength and direction of local and surrounding landscape influences on the local supply of an individual ES will drive its optimal landscape configuration. Accordingly, the net balance of these influences across multiple prioritized ES will determine the optimal configuration for landscape multifunctionality. Further, ES that share the same optimal configuration strategy form a bundle that can be managed together. Using data from German grasslands we demonstrate that the net-balance spatial interactions hypothesis is applicable to land-use planning scenarios that aim to maximize multiple ES. It allows general rules to be applied when local, detailed ES data is not available, and can help identify the best option to minimize trade-offs in the face of multiple competing land-use objectives
Plasticity of maritime pine (Pinus pinaster) wood-forming tissues during a growing season
Research• The seasonal effect is the most significant external source of variation affecting
vascular cambial activity and the development of newly divided cells, and hence
wood properties. Here, the effect of edapho-climatic conditions on the phenotypic
and molecular plasticity of differentiating secondary xylem during a growing season
was investigated.
• Wood-forming tissues of maritime pine (Pinus pinaster) were collected from the
beginning to the end of the growing season in 2003. Data from examination of fibre
morphology, Fourier-transform infrared spectroscopy (FTIR), analytical pyrolysis, and
gas chromatography/mass spectrometry (GC/MS) were combined to characterize the
samples. Strong variation was observed in response to changes in edapho-climatic
conditions.
• A genomic approach was used to identify genes differentially expressed during
this growing season. Out of 3512 studied genes, 19% showed a significant seasonal
effect. These genes were clustered into five distinct groups, the largest two representing
genes over-expressed in the early- or late-wood-forming tissues, respectively. The other
three clusters were characterized by responses to specific edapho-climatic conditions.
• This work provides new insights into the plasticity of the molecular machinery
involved in wood formation, and reveals candidate genes potentially responsible for
the phenotypic differences found between early- and late-wood
Transcriptomic Analysis Highlights Time-specific Embryonic Adaptation of Mice to the Lack of PrP
The physiological function of the PrP remains largely elusive. Its invalidation does not affect mouse survival and induces subtle phenotypes. To potentially assess this conundrum, we first comparatively analyzed the adult brain transcriptome of wild-type mice with that of transgenic mice invalidated at this locus either at the zygotic (ZĂĽrich PrP0/0 mice) or adult stages (NFH-Cre-Lox mice). Only subtle differences could be evidenced in the adult brains following microarray and QPCR analyses. When performed at an early adult stage, neuronal Prnp disruption appeared to sequentially induce an oxidative stress response and a nervous system remodeling, but it involved a limited number of only slightly modified genes. In sharp contrast, analysis at early embryonic stages, 7.5 and 8.5 dpc, just after the suspected normal time set of the Prnp locus activation, led to a transient perturbation of the transcriptome involving a larger number of genes and pointing to potential pathways related to the PrP physiological function. Overall, our data suggests an early adaptation of the mouse to the potentially detrimental lack of PrP during embryogenesis while its presence is less influential or redundant at later developmental stages
Background Light in Potential Sites for the ANTARES Undersea Neutrino Telescope
The ANTARES collaboration has performed a series of {\em in situ}
measurements to study the background light for a planned undersea neutrino
telescope. Such background can be caused by K decays or by biological
activity. We report on measurements at two sites in the Mediterranean Sea at
depths of 2400~m and 2700~m, respectively. Three photomultiplier tubes were
used to measure single counting rates and coincidence rates for pairs of tubes
at various distances. The background rate is seen to consist of three
components: a constant rate due to K decays, a continuum rate that
varies on a time scale of several hours simultaneously over distances up to at
least 40~m, and random bursts a few seconds long that are only correlated in
time over distances of the order of a meter. A trigger requiring coincidences
between nearby photomultiplier tubes should reduce the trigger rate for a
neutrino telescope to a manageable level with only a small loss in efficiency.Comment: 18 pages, 8 figures, accepted for publication in Astroparticle
Physic
Performance of the First ANTARES Detector Line
In this paper we report on the data recorded with the first Antares detector
line. The line was deployed on the 14th of February 2006 and was connected to
the readout two weeks later. Environmental data for one and a half years of
running are shown. Measurements of atmospheric muons from data taken from
selected runs during the first six months of operation are presented.
Performance figures in terms of time residuals and angular resolution are
given. Finally the angular distribution of atmospheric muons is presented and
from this the depth profile of the muon intensity is derived.Comment: 14 pages, 9 figure
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