2,093 research outputs found
A 16-channel Digital TDC Chip with internal buffering and selective readout for the DIRC Cherenkov counter of the BABAR experiment
A 16-channel digital TDC chip has been built for the DIRC Cherenkov counter
of the BaBar experiment at the SLAC B-factory (Stanford, USA). The binning is
0.5 ns, the conversion time 32 ns and the full-scale 32 mus. The data driven
architecture integrates channel buffering and selective readout of data falling
within a programmable time window. The time measuring scale is constantly
locked to the phase of the (external) clock. The linearity is better than 80 ps
rms. The dead time loss is less than 0.1% for incoherent random input at a rate
of 100 khz on each channel. At such a rate the power dissipation is less than
100 mw. The die size is 36 mm2.Comment: Latex, 18 pages, 13 figures (14 .eps files), submitted to NIM
The BMV project: Search for photon oscillations into massive particles
In this contribution to PSAS08 we report on the research activities developed
in our Toulouse group, in the framework of the BMV project, concerning the
search for photon oscillations into massive particles, such as axion-like
particles in the presence of a strong transverse magnetic field. We recall our
main result obtained in collaboration with LULI at \'Ecole Polytechnique
(Palaiseau, France). We also present the very preliminary results obtained with
the BMV experiment which is set up at LNCMP (Toulouse, France).Comment: Proceedings of PSAS'08, to be published in Can. J. Phy
Analytic curves in algebraic varieties over number fields
We establish algebraicity criteria for formal germs of curves in algebraic
varieties over number fields and apply them to derive a rationality criterion
for formal germs of functions, which extends the classical rationality theorems
of Borel-Dwork and P\'olya-Bertrandias valid over the projective line to
arbitrary algebraic curves over a number field.
The formulation and the proof of these criteria involve some basic notions in
Arakelov geometry, combined with complex and rigid analytic geometry (notably,
potential theory over complex and -adic curves). We also discuss geometric
analogues, pertaining to the algebraic geometry of projective surfaces, of
these arithmetic criteria.Comment: 55 pages. To appear in "Algebra, Arithmetic, and Geometry: In Honor
of Y.i. Manin", Y. Tschinkel & Yu. Manin editors, Birkh\"auser, 200
Clinical update: Heparin-induced thrombocytopenia: An update for the COVID-19 era
The increased use of heparin during the current COVID-19 pandemic has highlighted the risk of a rare but potentially serious complication of heparin therapy, viz. heparin-induced thrombocytopenia (HIT). This is a short review on the pharmacology of heparin and its derivatives, and the pathophysiology of HIT. Guidance on laboratory testing for and clinical management of HIT is presented in accordance with international guidelines. There are important similarities and differences between HIT and the new entity of vaccine-induced immune thrombotic thrombocytopenia, also known as thrombosis with thrombocytopenia syndrome, which clinicians need to be aware of
On FPL configurations with four sets of nested arches
The problem of counting the number of Fully Packed Loop (FPL) configurations
with four sets of a,b,c,d nested arches is addressed. It is shown that it may
be expressed as the problem of enumeration of tilings of a domain of the
triangular lattice with a conic singularity. After reexpression in terms of
non-intersecting lines, the Lindstr\"om-Gessel-Viennot theorem leads to a
formula as a sum of determinants. This is made quite explicit when
min(a,b,c,d)=1 or 2. We also find a compact determinant formula which generates
the numbers of configurations with b=d.Comment: 22 pages, TeX, 16 figures; a new formula for a generating function
adde
Regional scale rain-forest height mapping using regression-kriging of spaceborne and airborne lidar data : application on French Guiana
LiDAR data has been successfully used to estimate forest parameters such as canopy heights and biomass. Major limitation of LiDAR systems (airborne and spaceborne) arises from their limited spatial coverage. In this study, we present a technique for canopy height mapping using airborne and spaceborne LiDAR data (from the Geoscience Laser Altimeter System (GLAS)). First, canopy heights extracted from both airborne and spaceborne LiDAR were extrapolated from available environmental data. The estimated canopy height maps using Random Forest (RF) regression from airborne or GLAS calibration datasets showed similar precisions (~6 m). To improve the precision of canopy height estimates, regression-kriging was used. Results indicated an improvement in terms of root mean square error (RMSE, from 6.5 to 4.2 m) using the GLAS dataset, and from 5.8 to 1.8 m using the airborne LiDAR dataset. Finally, in order to investigate the impact of the spatial sampling of future LiDAR missions on canopy height estimates precision, six subsets were derived from the initial airborne LiDAR dataset. Results indicated that using the regression-kriging approach a precision of 1.8 m on the canopy height map was achievable with a flight line spacing of 5 km. This precision decreased to 4.8 m for flight line spacing of 50 km
Ătude exploratoire des caractĂ©ristiques professionnelles d'un Ă©chantillon de suicidants hospitalisĂ©s
Cette Ă©tude a pour objectif de dĂ©crire les caractĂ©ristiques professionnelles dâun Ă©chantillon de suicidants. Un enquĂȘteur a interrogĂ© les suicidants ĂągĂ©s de 18 Ă 65 ans, hospitalisĂ©s consĂ©cutivement dans une unitĂ© spĂ©cialisĂ©e du CHU dâAngers sur une durĂ©e de 6 mois et demi. Au total, 87 suicidants actifs avec un emploi ont Ă©tĂ© interrogĂ©s. Ils ont souvent Ă©tĂ© confrontĂ©s Ă des contraintes organisationnelles dĂ©crites dans la littĂ©rature comme responsables de souffrance mentale liĂ©e au travail. Cela concerne globalement autant les hommes que les femmes. En comparaison aux enquĂȘtes de santĂ© au travail (Sumer, SamotraceâŠ), les suicidants sont plus nombreux Ă ressentir entre autres un stress intense au travail, une conscience professionnelle heurtĂ©e et Ă ĂȘtre en situation tendue selon le modĂšle de Karasek. Cela pourrait ĂȘtre en faveur dâun lien entre les tentatives de suicide et certains facteurs de pĂ©nibilitĂ© mentale au travail. Les rĂ©sultats de cette Ă©tude sont Ă interprĂ©ter avec prudence du fait des phĂ©nomĂšnes de circularitĂ© des donnĂ©es et de la faiblesse de lâĂ©chantillon
New determinations of gamma-ray line intensities of the Ep = 550 keV and Ep = 1747 keV resonances of the 13-C(p,gamma)14-N reaction
Gamma-ray angular distributions for the resonances at Ep = 550 keV and 1747
keV of the radiative capture reaction 13-C(p,g)14-N have been measured, using
intense proton beams on isotopically pure 13-C targets. Relative intensities
for the strongest transitions were extracted with an accuracy of typically five
per cent, making these resonances new useful gamma-ray standards for efficiency
calibration in the energy range Egamma = 1.6 to 9 MeV.Comment: 17 pages, 6 figures, Nuclear Instruments and Methods, Sec. A,
accepte
Urban vulnerability and resilience within the context of climate change
Natural hazards, due to climate change, are particularly damaging in urban areas because of interdependencies of their networks. So, urban resilience has to face up to climate risks. The most impacting phenomenon is the urban heat island (UHI) effect. The storage capacity of heat is depending on shapes of buildings, public spaces, spatial organization, transport or even industrial activities. So, adaptive strategies for improving urban climate could be possible in different ways. In the framework of the French project Resilis, this study characterises urban vulnerability and resilience in terms of energy needs of buildings and outside urban comfort according to the IPCC carbon dioxide emission scenarios B2 and A2 for the period 2050â2100 for 10 French cities. The evolutions of four climate indicators in terms of heating and cooling needs and number of hours when the temperature is above 28 °C are then obtained for each city to analyse climate risks and their impacts in urban environment
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