3,589 research outputs found
A Novel Use of Light Guides and Wavelength Shifting Plates for the Detection of Scintillation Photons in Large Liquid Argon Detectors
Scintillation light generated as charged particles traverse large liquid
argon detectors adds valuable information to studies of weakly-interacting
particles. This paper uses both laboratory measurements and cosmic ray data
from the Blanche dewar facility at Fermilab to characterize the efficiency of
the photon detector technology developed at Indiana University for the single
phase far detector of DUNE. The efficiency of this technology was found to be
0.48% at the readout end when the detector components were characterized with
laboratory measurements. A second determination of the efficiency using cosmic
ray tracks is in reasonable agreement with the laboratory determination. The
agreement of these two efficiency determinations supports the result that
minimum ionizing muons generate photons/MeV as
they cross the LAr volume.Comment: Accepted version (without final editorial corrections
Quantification of Ophthalmic Changes After Long-Duration Spaceflight, and Subsequent Recovery
A subset of crewmembers are subjected to ophthalmic structure changes due to long-duration spaceflight (>6 months). Crewmembers who experience these changes are described as having Spaceflight Associated Neuro-Ocular Syndrome (SANS). Characteristics of SANS include optic disk edema, cotton wool spots, choroidal folds, refractive error, and posterior globe flattening. SANS remains a major obstacle to deep-space and planetary missions, requiring a better understanding of its etiology. Quantification of ocular, structural changes will improve our understanding of SANS pathophysiology. Methods were developed to quantify 3D optic nerve (ON) and ON sheath (ONS) geometries, ON tortuosity, and posterior globe deformation using MR imaging
Supernova type Ia luminosities, their dependence on second parameters, and the value of H_0
A sample of 35 SNe Ia with good to excellent photometry in B and V, minimum
internal absorption, and 1200 < v < \approx 30000 km/s is compiled from the
literature. As far as their spectra are known they are all Branch-normal. For
29 of the SNe Ia also peak magnitudes in I are known. The SNe Ia have uniform
colors at maximum, i.e. =-0.012 mag (sigma=0.051) and =-0.276 mag
(sigma=0.078). In the Hubble diagram they define a Hubble line with a scatter
of =0.21-0.16 mag, decreasing with wavelength. The scatter is further
reduced if the SNe Ia are corrected for differences in decline rate Delta_m_15
or color (B-V). A combined correction reduces the scatter to sigma<=0.13 mag.
After the correction no significant dependence remains on Hubble type or
galactocentric distance. The Hubble line suggests some curvature which can be
differently interpreted. A consistent solution is obtained for a cosmological
model with Omega_M=0.3, Omega_Lambda=0.7, which is indicated also by much more
distant SNe Ia. Absolute magnitudes are available for eight equally blue
(Branch-normal) SNe Ia in spirals, whose Cepheid distances are known. If their
well defined mean values of M_B, M_V, and M_I are used to fit the Hubble line
to the above sample of SNe Ia one obtains H_0=58.3 km/s/Mpc, or, after
adjusting all SNe Ia to the average values of Delta_m_15 and (B-V), H_0=60.9
km/s/Mpc. Various systematic errors are discussed whose elimination tends to
decrease H_0. The finally adopted value at the 90-percent level, including
random and systematic errors, is H_0=58.5 +/- 6.3 km/s/Mpc. Several higher
values of H_0 from SNe Ia, as suggested in the literature, are found to depend
on large corrections for variations of the light curve parameter and/or on an
unwarranted reduction of the Cepheid distances of the calibrating SNe Ia.Comment: 42 pages, including 9 figures; submitted to Ap
Teaching Hispanic restaurant workers: Translanguaging as culturally sustaining pedagogy
In this article, we make a case for incorporating translanguaging pedagogy into the framework of Culturally Sustaining Pedagogy (CSP). Drawing on data from a one-year ethnographic study of an adult ESL program, we show how teachers believed in and attempted to create spaces for translanguaging and CSP, but in practice fell short. We conclude that translanguaging is most powerful when understood as a component of CSP but call for more research in this area.Accepted manuscrip
Dirac Spinor Waves and Solitons in Anisotropic Taub-NUT Spaces
We apply a new general method of anholonomic frames with associated nonlinear
connection structure to construct new classes of exact solutions of
Einstein-Dirac equations in five dimensional (5D)gravity. Such solutions are
parametrized by off-diagonal metrics in coordinate (holonomic) bases, or,
equivalently, by diagonal metrics given with respect to some anholonomic frames
(pentads, or funfbiends, satisfing corresponding constraint relations). We
consider two possibilities of generalization of the Taub NUT metric in order to
obtain vacuum solutions of 5D Einsitein equations with effective
renormalization of constants having distinguished anisotropies on an angular
parameter or on extra dimension coordinate. The constructions are extended to
solutions describing self-consistent propagations of 3D Dirac wave packets in
5D anisotropic Taub NUT spacetimes. We show that such anisotropic
configurations of spinor matter can induce gravitational 3D solitons being
solutions of Kadomtsev-Petviashvili or of sine-Gordon equations.Comment: revtex, 16 pages, version 4, affiliation changed, accepted to CQ
Dynamical algebra and Dirac quantum modes in Taub-NUT background
The SO(4,1) gauge-invariant theory of the Dirac fermions in the external
field of the Kaluza-Klein monopole is investigated. It is shown that the
discrete quantum modes are governed by reducible representations of the o(4)
dynamical algebra generated by the components of the angular momentum operator
and those of the Runge-Lenz operator of the Dirac theory in Taub-NUT
background. The consequence is that there exist central and axial discrete
modes whose spinors have no separated variables.Comment: 17 pages, latex, no figures. Version to appear in Class.Quantum Gra
Geometrical dynamics of Born-Infeld objects
We present a geometrical inspired study of the dynamics of -branes. We
focus on the usual nonpolynomial Dirac-Born-Infeld action for the worldvolume
swept out by the brane in its evolution in general background spacetimes. We
emphasize the form of the resulting equations of motion which are quite simple
and resemble Newton's second law, complemented with a conservation law for a
worldvolume bicurrent. We take a closer look at the classical Hamiltonian
analysis which is supported by the ADM framework of general relativity. The
constraints and their algebra are identified as well as the geometrical role
they play in phase space. In order to illustrate our results, we review the
dynamics of a -brane immersed in a background spacetime.
We exhibit the mechanical properties of Born-Infeld objects paving the way to a
consistent quantum formulation.Comment: LaTex, 20 pages, no figure
The Good, the Bad, and the Ugly: Statistical quality assessment of SZ detections
International audienceWe examine three approaches to the problem of source classification in catalogues. Our goal is to determine the confidence withwhich the elements in these catalogues can be distinguished in populations on the basis of their spectral energy distribution (SED).Our analysis is based on the projection of the measurements onto a comprehensive SED model of the main signals in the consideredrange of frequencies. We first consider likelihood analysis, which is halfway between supervised and unsupervised methods. Next, weinvestigate an unsupervised clustering technique. Finally, we consider a supervised classifier based on artificial neural networks. Weillustrate the approach and results using catalogues from various surveys, such as X-rays (MCXC), optical (SDSS), and millimetric(Planck Sunyaev-Zeldovich (SZ)). We show that the results from the statistical classifications of the three methods are in very goodagreement with each other, although the supervised neural network-based classification shows better performance allowing the bestseparation into populations of reliable and unreliable sources in catalogues. The latest method was applied to the SZ sources detectedby the Planck satellite. It led to a classification assessing and thereby agreeing with the reliability assessment published in the PlanckSZ catalogue. Our method could easily be applied to catalogues from future large surveys such as SRG/eROSITA and Euclid
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