7,403 research outputs found
Grille spectrometer (grille)
The Grille spectrometer was designed and flown on Spaceklab 1 by two organizations: The Office National d'Etudes et de Recherches Aerospatiales in France and the Belgian Institute for Space Aeronomy in Belgium. Its purpose is to study, on a global scale, atmospheric parameters between 15 and 150 km altitude. The investigation uses high-resolution (better than 0.1/cm) spectroscopic observations of the earth's limb in the wavelength range characteristic of the vibrational-rotational lines of the relevant atmospheric constituents. Characteristics and proposed modifications of the grille spectrometer are described. This instrument will be part of the atmospheric science research payload flown on the Atmospheric Laboratory for Applications and Science (ATLAS 1) NASA mission planned for late 1990
From vertex detectors to inner trackers with CMOS pixel sensors
The use of CMOS Pixel Sensors (CPS) for high resolution and low material
vertex detectors has been validated with the 2014 and 2015 physics runs of the
STAR-PXL detector at RHIC/BNL. This opens the door to the use of CPS for inner
tracking devices, with 10-100 times larger sensitive area, which require
therefore a sensor design privileging power saving, response uniformity and
robustness. The 350 nm CMOS technology used for the STAR-PXL sensors was
considered as too poorly suited to upcoming applications like the upgraded
ALICE Inner Tracking System (ITS), which requires sensors with one order of
magnitude improvement on readout speed and improved radiation tolerance. This
triggered the exploration of a deeper sub-micron CMOS technology, Tower-Jazz
180 nm, for the design of a CPS well adapted for the new ALICE-ITS running
conditions. This paper reports the R&D results for the conception of a CPS well
adapted for the ALICE-ITS.Comment: 4 pages, 4 figures, VCI 2016 conference proceeding
An integrative clustering approach combining particle swarm optimization and formal concept analysis
Charm meson resonances in decays
Motivated by recent experimental results we reconsider semileptonic decays within a model which combines heavy quark symmetry and
properties of the chiral Lagrangian. We include excited charm meson states,
some of them recently observed, in our Lagrangian and determine their impact on
the charm meson semileptonic form factors. We find that the inclusion of
excited charm meson states in the model leads to a rather good agreement with
the experimental results on the shape of the form factor. We
also calculate branching ratios for all decays.Comment: 9 pages, 4 figures; minor corrections, added some discussion, version
as publishe
Entropies, volumes, and Einstein metrics
We survey the definitions and some important properties of several asymptotic
invariants of smooth manifolds, and discuss some open questions related to
them. We prove that the (non-)vanishing of the minimal volume is a
differentiable property, which is not invariant under homeomorphisms. We also
formulate an obstruction to the existence of Einstein metrics on four-manifolds
involving the volume entropy. This generalizes both the Gromov--Hitchin--Thorpe
inequality and Sambusetti's obstruction.Comment: This is a substantial revision and expansion of the 2004 preprint,
which I prepared in spring of 2010 and which has since been published. The
version here is essentially the published one, minus the problems introduced
by Springer productio
Concurrent anodal transcranial direct-current stimulation and motor task to influence sensorimotor cortex activation
Functional targeting with anodal high-definition transcranial direct current stimulation (HD-atDCS) of involved brain areas during performance of a motor task (online) may facilitate sensorimotor cortex neuroplasticity compared to performing the motor task after HD-atDCS (offline). The aim of this study was to employ functional near-infrared spectroscopy to compare the time course of motor task-related changes in sensorimotor cortex activation between online and offline HD-atDCS. We hypothesized that online HD-atDCS would have a greater effect on task-related sensorimotor cortex activation than offline HD-atDCS. In a within-subject sham controlled and randomized study design, 9 healthy participants underwent 3 HD-atDCS sessions (online, offline and sham) targeting the left sensorimotor cortex separated by 1 week. Functional near-infrared spectroscopy hemodynamic changes were measured from the left sensorimotor cortex during a simple finger opposition motor task before (Pre), immediately (T1) and 30 min after (T2) each session. The movement rates were not different between (online, offline, sham) or within (Pre, T1, T2) sessions. At T2, online HD-atDCS was associated with a significant increase (large effect size) in sensorimotor cortex activation (Hedges g = 1.01, p<0.001) when compared to sham; there was a nonsignificant trend to increase activation between offline and sham (Hedges g = 0.52, p=0.05) and between online and offline (Hedges g = 0.53, p=0.06). Concurrent application of HD-atDCS during a motor task may produce larger sensorimotor cortex activation than sequential application
Atomic structure and vibrational properties of icosahedral BC boron carbide
The atomic structure of icosahedral BC boron carbide is determined by
comparing existing infra-red absorption and Raman diffusion measurements with
the predictions of accurate {\it ab initio} lattice-dynamical calculations
performed for different structural models. This allows us to unambiguously
determine the location of the carbon atom within the boron icosahedron, a task
presently beyond X-ray and neutron diffraction ability. By examining the inter-
and intra-icosahedral contributions to the stiffness we show that, contrary to
recent conjectures, intra-icosahedral bonds are harder.Comment: 9 pages including 3 figures, accepted in Physical Review Letter
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