6,086 research outputs found
ReDecay: A novel approach to speed up the simulation at LHCb
With the steady increase in the precision of flavour physics measurements
collected during LHC Run 2, the LHCb experiment requires simulated data samples
of larger and larger sizes to study the detector response in detail. The
simulation of the detector response is the main contribution to the time needed
to simulate full events. This time scales linearly with the particle
multiplicity. Of the dozens of particles present in the simulation only the few
participating in the signal decay under study are of interest, while all
remaining particles mainly affect the resolutions and efficiencies of the
detector. This paper presents a novel development for the LHCb simulation
software which re-uses the rest of the event from previously simulated events.
This approach achieves an order of magnitude increase in speed and the same
quality compared to the nominal simulation
Dimensionality of the spatio-temporal entanglement of PDC photon pairs
In this work the Schmidt number of the two-photon state generated by
parametric-down conversion (PDC) is evaluated in the framework of a fully
spatio-temporal model for PDC. A comparison with the results obtained in either
purely spatial or purely temporal models shows that the degree of entanglement
of the PDC state cannot be trivially reduced to the product of the Schmidt
numbers obtained in models with lower dimensionality, unless the detected
bandwidth is very narrow. This result is a consequence of the non-factorability
of the state in the spatial and temporal degrees of freedoms of twin photons.
In the limit of a broad pump beam, we provide a geometrical interpretation of
the Schmidt number, as the ratio between the volume of the phase matching
region and of a correlation volume.Comment: 17 pages, 10 figures. Submitted to Phys. Rev.
Determinanti e strategie del post-vendita
L'articolo prende spunto dalle evidenze emerse da una ricerca condotta sul tema dei processi post-vendita nel contesto delle imprese operanti in diversi settori di beni durevoli. In particolare, l'articolo, dopo aver messo in luce il ruolo dei servizi post-vendita nel processo di creazione di valore aziendale, presenta ed analizza le diverse possibili configurazioni strategiche che tali attivit\ue0 possono assumere
Two new pulsating low-mass pre-white dwarfs or SX Phenix stars?*
Context. The discovery of pulsations in low-mass stars opens an opportunity
for probing their interiors and to determine their evolution, by employing the
tools of asteroseismology. Aims. We aim to analyze high-speed photometry of
SDSSJ145847.02070754.46 and SDSSJ173001.94070600.25 and discover
brightness variabilities. In order to locate these stars in the diagram we fit optical spectra (SDSS) with synthetic non-magnetic
spectra derived from model atmospheres. Methods. To carry out this study, we
used the photometric data obtained by us for these stars with the 2.15m
telescope at CASLEO, Argentina. We analyzed their light curves and we apply the
Discrete Fourier Transform to determine the pulsation frequencies. Finally, we
compare both stars in the diagram, with known two
pre-white dwarfs, seven pulsating pre-ELM white dwarf stars, Scuti and
SX Phe stars. Results. We report the discovery of pulsations in
SDSSJ145847.02070754.46 and SDSSJ173001.94070600.25. We determine their
effective temperature and surface gravity to be = 7 972 200
K, = 4.25 0.5 and = 7 925 200 K, =
4.25 0.5, respectively. With these parameters these new pulsating
low-mass stars can be identified with either ELM white dwarfs (with ~ 0.17 Mo)
or more massive SX Phe stars. We identified pulsation periods of 3 278.7 and 1
633.9 s for SDSSJ145847.02070754.46 and a pulsation period of 3 367.1 s for
SDSSJ173001.94070600.25. These two new objects together with those of Maxted
et al. (2013, 2014) indicate the possible existence of a new instability domain
towards the late stages of evolution of low-mass white dwarf stars, although
their identification with SX Phe stars cannot be discarded.Comment: 5 pages, 5 figures, 1 table, accepted for publication in A&A
Caldera collapse and tectonics along the Main Ethiopian Rift: Reviewing possible relationships
The Main Ethiopian Rift (MER) represents an area where volcanism and tectonics interact to create closely linked volcano-tectonic features. This linkage is paramount in the axial portion of the rift, where magmatic segments localize several large peralkaline eruptive centres. Many of them evolved into caldera collapse (the best preserved of which are younger than ) generating large ignimbrites and registering the interaction between magmatism and tectonics along the MER. In this work we review the structure of the main collapsed calderas along the axial portion of the MER, to summarize the relationships between volcanism and tectonics proposed in the literature explaining their structural evolution. By doing this, we infer that tectonics had a strong influence in controlling the elongation of the majority of examined calderas. This control was induced by reactivation of inherited crustal fabrics or by stretching of the magma reservoirs under the MER regional stress field
Strain partitioning in host rock controls LREE release from allanite-(Ce) in subduction zones
Combined microstructural, mineral chemical, X-ray maps, and X-ray single-crystal diffraction analyses are used to reveal the rheological behaviour of individual grains of magmatic allanite relicts hosted in variably deformed metagranitoids at Lago della Vecchia (inner part of the Sesia-Lanzo Zone, Western Alps, Europe), which experienced high pressure and low temperature metamorphism during the Alpine subduction. X-ray single crystal diffraction shows that none of the allanite crystals, irrespective of the strain state of the host rock, record any evidence of plastic deformation (i.e., intracrystalline deformation), as indicated by the shape of the Bragg diffraction spots, the atomic site positions, and their displacement around the centre of gravity. On the contrary, strong plastic deformation affected matrix minerals, such as quartz, white mica, and feldspar of the hosting rocks, during the development of the Alpine eclogitic- and blueschist-facies metamorphism. Despite the strain-free atomic structures of allanite, different patterns of chemical zoning, as a function of strain accumulated in the rock matrix, are observed. Since allanite occurs in magmatic and metamorphic rocks and it is stable at high pressure and low temperature conditions, we infer that allanite could behave as one of the main carriers of light-rare-earth-elements into the mantle wedge during subduction of continental crust. In particular, the release of light-rare-earth-elements from allanite, under high pressure conditions in subduction zones, is facilitated by high strain accumulated in the host rock
Методика и методология социолингвистических исследований в условиях билингвизма и диглоссии
Lithospheric-scale analogue models are used to analyse the parameters controlling the typical evolution of deformation during continental narrow rifting, characterized by early activation of large boundary faults and basin subsidence, followed by localization of tectonic activity in internal faults at the rift axis. Integration of current and previous experiments shows that the evolution of deformation, in particular the amount of extension needed for the abandonment of boundary faults and migration of deformation to in-rift faults, is dependent on at least five boundary conditions: (i) thickness of brittle layers (including syn-rift sediments); (ii) thickness of ductile layers; (iii) extension rate; (iv) width of the weak zone localizing extension; and (v) rift obliquity with respect to the extension direction. An increase in the amount of extension corresponding to the inward migration of faulting (i.e., a longer phase of slip on boundary faults) is observed for (a) an increase in the thickness of both brittle and ductile crustal layers and syn-rift sediment accumulation, (b) a decrease in extension rate and width of the weak zone, and (c) a decrease in rift obliquity. A unified account of these correlations is presented, based on the hypothesis that fault migration occurs when boundary faults can no longer accommodate the imposed bulk extension, leading to time-space variations of internal strain and strain rate (and consequently stress) in the ductile layers which overcome the total resistance of brittle layers to thoroughgoing faulting
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