1,187 research outputs found
Investigation of relationships between linears, tonal and hazy anomalies, and petroleum production in the Williston Basin: An ERTS approach
There are no author-identified significant results in this report
A Continuous 100-mK Helium-Light Cooling System for MUSCAT on the LMT
The MUSCAT instrument is a large-format camera planned for installation on
the Large Millimeter Telescope (LMT) in 2018. MUSCAT requires continuous
cooling of several large-volume stages to sub-Kelvin temperatures, with the
focal plane cooled to 100 mK. Through the use of continuous sorption coolers
and a miniature dilution refrigerator, the MUSCAT project can fulfil its
cryogenic requirements at a fraction of the cost and space required for
conventional dilution systems. Our design is a helium-light system, using a
total of only 9 litres of helium-3 across several continuous cooling systems,
cooling from 4 K to 100 mK. Here we describe the operation of both the
continuous sorption and the miniature dilution refrigerator systems used in
this system, along with the overall thermal design and budgeting of MUSCAT.
MUSCAT will represent the first deployment of these new technologies in a
science-grade instrument and will prove the concept as a viable option for
future large-scale experiments such as CMB-S4.Comment: Presented at 17th International Workshop on Low-Temperature
Detectors. Published in Journal of Low Temperature Physics, 201
Determination of Fluoxetine and Norfluoxetine Concentrations in Cadaveric Allograft Skin
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90146/1/j.1875-9114.1998.tb03908.x.pd
A note on behaviour at an isotropic singularity
The behaviour of Jacobi fields along a time-like geodesic running into an
isotropic singularity is studied. It is shown that the Jacobi fields are
crushed to zero length at a rate which is the same in every direction
orthogonal to the geodesic. We show by means of a counter-example that this
crushing effect depends crucially on a technicality of the definition of
isotropic singularities, and not just on the uniform degeneracy of the metric
at the singularity.Comment: 13 pp. plain latex. To appear in Classical and Quantum Gravit
On the existence of dyons and dyonic black holes in Einstein-Yang-Mills theory
We study dyonic soliton and black hole solutions of the
Einstein-Yang-Mills equations in asymptotically anti-de Sitter space. We prove
the existence of non-trivial dyonic soliton and black hole solutions in a
neighbourhood of the trivial solution. For these solutions the magnetic gauge
field function has no zeros and we conjecture that at least some of these
non-trivial solutions will be stable. The global existence proof uses local
existence results and a non-linear perturbation argument based on the (Banach
space) implicit function theorem.Comment: 23 pages, 2 figures. Minor revisions; references adde
Molecular Genetic Influences on Normative and Problematic Alcohol Use in a Population-Based Sample of College Students
Background: Genetic factors impact alcohol use behaviors and these factors may become increasingly evident during emerging adulthood. Examination of the effects of individual variants as well as aggregate genetic variation can clarify mechanisms underlying risk.
Methods: We conducted genome-wide association studies (GWAS) in an ethnically diverse sample of college students for three quantitative outcomes including typical monthly alcohol consumption, alcohol problems, and maximum number of drinks in 24 h. Heritability based on common genetic variants (h2SNP) was assessed. We also evaluated whether risk variants in aggregate were associated with alcohol use outcomes in an independent sample of young adults.
Results: Two genome-wide significant markers were observed: rs11201929 in GRID1 for maximum drinks in 24 h, with supportive evidence across all ancestry groups; and rs73317305 in SAMD12 (alcohol problems), tested only in the African ancestry group. The h2SNP estimate was 0.19 (SE = 0.11) for consumption, and was non-significant for other outcomes. Genome-wide polygenic scores were significantly associated with alcohol outcomes in an independent sample.
Conclusions: These results robustly identify genetic risk for alcohol use outcomes at the variant level and in aggregate. We confirm prior evidence that genetic variation in GRID1impacts alcohol use, and identify novel loci of interest for multiple alcohol outcomes in emerging adults. These findings indicate that genetic variation influencing normative and problematic alcohol use is, to some extent, convergent across ancestry groups. Studying college populations represents a promising avenue by which to obtain large, diverse samples for gene identification
Even perturbations of self-similar Vaidya space-time
We study even parity metric and matter perturbations of all angular modes in
self-similar Vaidya space-time. We focus on the case where the background
contains a naked singularity. Initial conditions are imposed describing a
finite perturbation emerging from the portion of flat space-time preceding the
matter-filled region of space-time. The most general perturbation satisfying
the initial conditions is allowed impinge upon the Cauchy horizon (CH), whereat
the perturbation remains finite: there is no ``blue-sheet'' instability.
However when the perturbation evolves through the CH and onto the second future
similarity horizon of the naked singularity, divergence necessarily occurs:
this surface is found to be unstable. The analysis is based on the study of
individual modes following a Mellin transform of the perturbation. We present
an argument that the full perturbation remains finite after resummation of the
(possibly infinite number of) modes.Comment: Accepted for publication in Physical Review D, 27 page
An avalanche-photodiode-based photon-number-resolving detector
Avalanche photodiodes are widely used as practical detectors of single
photons.1 Although conventional devices respond to one or more photons, they
cannot resolve the number in the incident pulse or short time interval.
However, such photon number resolving detectors are urgently needed for
applications in quantum computing,2-4 communications5 and interferometry,6 as
well as for extending the applicability of quantum detection generally. Here we
show that, contrary to current belief,3,4 avalanche photodiodes are capable of
detecting photon number, using a technique to measure very weak avalanches at
the early stage of their development. Under such conditions the output signal
from the avalanche photodiode is proportional to the number of photons in the
incident pulse. As a compact, mass-manufactured device, operating without
cryogens and at telecom wavelengths, it offers a practical solution for photon
number detection.Comment: 12 pages, 4 figure
A Characterisation of Strong Wave Tails in Curved Space-Times
A characterisation of when wave tails are strong is proposed. The existence
of a curvature induced tail (i.e. a Green's function term whose support
includes the interior of the light-cone) is commonly understood to cause
backscattering of the field governed by the relevant wave equation. Strong
tails are characterised as those for which the purely radiative part of the
field is backscattered. With this definition, it is shown that electromagnetic
waves in asymptotically flat space-times and fields governed by tail-free
propagation have weak tails, but minimally coupled scalar fields in a
cosmological scenario have strong tails.Comment: 17 pages, Revtex, to appear in Classical and Quantum Gravit
- …