5,195 research outputs found
Test with cosmic rays of the GEM chambers for the LHCb muon system produced in Cagliari
The inner region of the first LHCb muon station will be equipped with twelve Gas Electron Multiplier chambers. The seven chambers produced in Cagliari were studied for several days each using cosmic rays. We measured the efficiency, timing resolution, and uniformity, cluster-size and out-of-time multiplicity. We find all seven chambers perform well
Hadron detection with a dual-readout fiber calorimeter
In this paper, we describe measurements of the response functions of a
fiber-based dual- readout calorimeter for pions, protons and multiparticle
"jets" with energies in the range from 10 to 180 GeV. The calorimeter uses lead
as absorber material and has a total mass of 1350 kg. It is complemented by
leakage counters made of scintillating plastic, with a total mass of 500 kg.
The effects of these leakage counters on the calorimeter performance are
studied as well. In a separate section, we investigate and compare different
methods to measure the energy resolution of a calorimeter. Using only the
signals provided by the calorimeter, we demonstrate that our dual-readout
calorimeter, calibrated with electrons, is able to reconstruct the energy of
proton and pion beam particles to within a few percent at all energies. The
fractional widths of the signal distributions for these particles (sigma/E)
scale with the beam energy as 30%/sqrt(E), without any additional contributing
terms
Red coral extinction risk enhanced by ocean acidification
The red coral Corallium rubrum is a habitat-forming species with a prominent and structural role in mesophotic habitats, which sustains biodiversity hotspots. This precious coral is threatened by both over-exploitation and temperature driven mass mortality events. We report here that biocalcification, growth rates and polyps’ (feeding) activity of Corallium rubrum are significantly reduced at pCO2 scenarios predicted for the end of this century (0.2 pH decrease). Since C. rubrum is a long-living species (.200 years), our results suggest that ocean acidification predicted for 2100 will significantly increases the risk of extinction of present populations. Given the functional role of these corals in the mesophotic zone, we predict that ocean acidification might have cascading effects on the functioning of these habitats worldwid
Internal rotation of the red-giant star KIC 4448777 by means of asteroseismic inversion
In this paper we study the dynamics of the stellar interior of the early
red-giant star KIC 4448777 by asteroseismic inversion of 14 splittings of the
dipole mixed modes obtained from {\it Kepler} observations. In order to
overcome the complexity of the oscillation pattern typical of red-giant stars,
we present a procedure which involves a combination of different methods to
extract the rotational splittings from the power spectrum. We find not only
that the core rotates faster than the surface, confirming previous inversion
results generated for other red giants (Deheuvels et al. 2012,2014), but we
also estimate the variation of the angular velocity within the helium core with
a spatial resolution of and verify the hypothesis of a sharp
discontinuity in the inner stellar rotation (Deheuvels et al. 2014). The
results show that the entire core rotates rigidly with an angular velocity of
about ~nHz and provide evidence for an
angular velocity decrease through a region between the helium core and part of
the hydrogen burning shell; however we do not succeed to characterize the
rotational slope, due to the intrinsic limits of the applied techniques. The
angular velocity, from the edge of the core and through the hydrogen burning
shell, appears to decrease with increasing distance from the center, reaching
an average value in the convective envelope of
~nHz. Hence, the core in KIC~4448777 is
rotating from a minimum of 8 to a maximum of 17 times faster than the envelope.
We conclude that a set of data which includes only dipolar modes is sufficient
to infer quite accurately the rotation of a red giant not only in the dense
core but also, with a lower level of confidence, in part of the radiative
region and in the convective envelope.Comment: accepted for publication on Ap
Internal rotation of red giants by asteroseismology
We present an asteroseismic approach to study the dynamics of the stellar
interior in red-giant stars by asteroseismic inversion of the splittings
induced by the stellar rotation on the oscillation frequencies. We show
preliminary results obtained for the red giant KIC4448777 observed by the space
mission Kepler.Comment: 3 pages, 4 figures, the 40th Liege International Astrophysical
Colloquium Liac40, 'Ageing low mass stars: from red giants to white dwarfs',
to be published on EPJ Web of Conference
Rapid enhancement of touch from non-informative vision of the hand
Processing in one sensory modality may modulate processing in another. Here we investigate how simply viewing the hand can influence the sense of touch. Previous studies showed that non-informative vision of the hand enhances tactile acuity, relative to viewing an object at the same location. However, it remains unclear whether this Visual Enhancement of Touch (VET) involves a phasic enhancement of tactile processing circuits triggered by the visual event of seeing the hand, or more prolonged, tonic neuroplastic changes, such as recruitment of additional cortical areas for tactile processing. We recorded somatosensory evoked potentials (SEPs) evoked by electrical stimulation of the right middle finger, both before and shortly after viewing either the right hand, or a neutral object presented via a mirror. Crucially, and unlike prior studies, our visual exposures were unpredictable and brief, in addition to being non-informative about touch. Viewing the hand, as opposed to viewing an object, enhanced tactile spatial discrimination measured using grating orientation judgements, and also the P50 SEP component, which has been linked to early somatosensory cortical processing. This was a trial-specific, phasic effect, occurring within a few seconds of each visual onset, rather than an accumulating, tonic effect. Thus, somatosensory cortical modulation can be triggered even by a brief, non-informative glimpse of one’s hand. Such rapid multisensory modulation reveals novel aspects of the specialised brain systems for functionally representing the body
Seeing the body distorts tactile size perception
Vision of the body modulates somatosensation, even when entirely non-informative about stimulation. For example, seeing the body increases tactile spatial acuity, but reduces acute pain. While previous results demonstrate that vision of the body modulates somatosensory sensitivity, it is unknown whether vision also affects metric properties of touch, and if so how. This study investigated how non-informative vision of the body modulates tactile size perception. We used the mirror box illusion to induce the illusion that participants were directly seeing their stimulated left hand, though they actually saw their reflected right hand. We manipulated whether participants: (a) had the illusion of directly seeing their stimulated left hand, (b) had the illusion of seeing a non-body object at the same location, or (c) looked directly at their non-stimulated right-hand. Participants made verbal estimates of the perceived distance between two tactile stimuli presented simultaneously to the dorsum of the left hand, either 20, 30, or 40 mm apart. Vision of the body significantly reduced the perceived size of touch, compared to vision of the object or of the contralateral hand. In contrast, no apparent changes of perceived hand size were found. These results show that seeing the body distorts tactile size perception
Morphological evolution in marmots (Rodentia, Sciuridae): size and shape of the dorsal and lateral surfaces of the cranium
"Über den Stand der Bergungsarbeiten in den Trümmern des eingestürzten Kölner Stadtarchivs hat sich der Kulturausschuss des Landtags unter Vorsitz von Dr. Fritz Behrens am Mittwochnachmittag in einer aktuellen Viertelstunde unterrichten lassen. Kulturstaatssekretär Hans-Heinrich Grosse-Brockhoff informierte die Abgeordneten über die laufenden Maßnahmen und die landesweite Unterstützung zur Rettung möglichst vieler historischer Dokumente. Die Ausschussmitglieder zeigten sich betroffen über den..
Dual-readout Calorimetry
The RD52 Project at CERN is a pure instrumentation experiment whose goal is
to understand the fundamental limitations to hadronic energy resolution, and
other aspects of energy measurement, in high energy calorimeters. We have found
that dual-readout calorimetry provides heretofore unprecedented information
event-by-event for energy resolution, linearity of response, ease and
robustness of calibration, fidelity of data, and particle identification,
including energy lost to binding energy in nuclear break-up. We believe that
hadronic energy resolutions of {\sigma}/E 1 - 2% are within reach for
dual-readout calorimeters, enabling for the first time comparable measurement
preci- sions on electrons, photons, muons, and quarks (jets). We briefly
describe our current progress and near-term future plans. Complete information
on all aspects of our work is available at the RD52 website
http://highenergy.phys.ttu.edu/dream/.Comment: 10 pages, 10 figures, Snowmass White pape
Insights from a Murine Aortic Transplantation Model
Transplant vasculopathy (TV) represents a major obstacle to long-term graft
survival and correlates with severity of ischemia reperfusion injury (IRI).
Donor administration of the nitric oxide synthases (NOS) co-factor
tetrahydrobiopterin has been shown to prevent IRI. Herein, we analysed whether
tetrahydrobiopterin is also involved in TV development. Using a fully
allogeneic mismatched (BALB/c to C57BL/6) murine aortic transplantation model
grafts subjected to long cold ischemia time developed severe TV with intimal
hyperplasia (α-smooth muscle actin positive cells in the neointima) and
endothelial activation (increased P-selectin expression). Donor pretreatment
with tetrahydrobiopterin significantly minimised these changes resulting in
only marginal TV development. Severe TV observed in the non-treated group was
associated with increased protein oxidation and increased occurrence of
endothelial NOS monomers in the aortic grafts already during graft
procurement. Tetrahydrobiopterin supplementation of the donor prevented all
these early oxidative changes in the graft. Non-treated allogeneic grafts
without cold ischemia time and syngeneic grafts did not develop any TV. We
identified early protein oxidation and impaired endothelial NOS homodimer
formation as plausible mechanistic explanation for the crucial role of IRI in
triggering TV in transplanted aortic grafts. Therefore, targeting endothelial
NOS in the donor represents a promising strategy to minimise TV
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