18,861 research outputs found
Consideration of radar target glint from ST during OMV rendezvous
The nature of radar target glint and the factors upon which it depends when using the Hubble Space Telescope as a radar target is discussed. An analysis of the glint problem using a 35 MHz or 94 MHz radar on the orbital maneuvering vehicle is explored. A strategy for overcoming glint is suggested
A very deep Chandra observation of Abell 1795: The Cold Front and Cooling Wake
We present a new analysis of very deep Chandra observations of the galaxy
cluster Abell 1795. Utilizing nearly 750 ks of net ACIS imaging, we are able to
resolve the thermodynamic structure of the Intracluster Medium (ICM) on length
scales of ~ 1 kpc near the cool core. We find several previously unresolved
structures, including a high pressure feature to the north of the BCG that
appears to arise from the bulk motion of Abell 1795's cool core. To the south
of the cool core, we find low temperature (~ 3 keV), diffuse ICM gas extending
for distances of ~ 50 kpc spatially coincident with previously identified
filaments of H-alpha emission. Gas at similar temperatures is also detected in
adjacent regions without any H-alpha emission. The X-ray gas coincident with
the H-alpha filament has been measured to be cooling spectroscopically at a
rate of ~ 1 Solar Masses/ yr, consistent with measurements of the star
formation rate in this region as inferred from UV observations, suggesting that
the star formation in this filament as inferred by its H and UV
emission can trace its origin to the rapid cooling of dense, X-ray emitting
gas. The H-alpha filament is not a unique site of cooler ICM, however, as ICM
at similar temperatures and even higher metallicities not cospatial with
H emission is observed just to the west of the H-alpha filament,
suggesting that it may have been uplifted by Abell 1795's central active
galaxy. Further simulations of cool core sloshing and AGN feedback operating in
concert with one another will be necessary to understand how such a dynamic
cool core region may have originated and why the H-alpha emission is so
localized with respect to the cool X-ray gas despite the evidence for a
catastrophic cooling flow.Comment: 14 Pages, 10 Figures, Resubmitted to ApJ after first referee report,
Higher Resolution Figures available upon reques
Resonance assignments for latherin, a natural surfactant protein from horse sweat
Latherin is an intrinsically surfactant protein of ~23Â kDa found in the sweat and saliva of horses. Its function is probably to enhance the translocation of sweat water from the skin to the surface of the pelt for evaporative cooling. Its role in saliva may be to enhance the wetting, softening and maceration of the dry, fibrous food for which equines are adapted. Latherin is unusual in its relatively high content of aliphatic amino acids (~25Â % leucines) that might contribute to its surfactant properties. Latherin is related to the palate, lung, and nasal epithelium carcinoma-associated proteins (PLUNCs) of mammals, at least one of which is now known to exhibit similar surfactant activity to latherin. No structures of any PLUNC protein are currently available. 15N,13C-labelled recombinant latherin was produced in Escherichia coli, and essentially all of the resonances were assigned despite the signal overlap due to the preponderance of leucines. The most notable exceptions include a number of residues located in an apparently dynamic loop region between residues 145 and 154. The assignments have been deposited with BMRB accession number 19067
Mental Health and Substance Abuse Issues Among Native Americans Living on a Remote Reservation: Results from a Community Survey
The purpose of the study was to document the perceived and actual mental health and substance abuse issues of residents living on a remote reservation in the Northwestern United States. Surveys were completed by 138 Native Americans, who reported on mental health status and problems, perceptions of personal and community health issues on the reservation, and patterns of substance use and abuse (e.g., how often respondents use alcohol, what drugs present the most serious problems on the reservation). The respondents perceived their own mental health to be quite good. However, they reported that several mental health problems were prevalent in their community including alcohol/drug abuse, mood disorders, and spousal abuse/domestic violence. In addition, although respondents themselves reported little substance abuse, the most serious perceived problems in both their families and the community were related to substance abuse. Respondents not only recognized the problems caused by substance abuse on the reservation; they also had valuable suggestions for how to reduce this problem, including recreational/after school programs, education about substance abuse, cultural activities, and appropriate treatment services, including traditional or faith-based healing methods
Health Care Provider’s Perceptions of the Transition Between Pediatric to Adolescent and Adulthood: A Qualitative Inquiry
This study examines the current practices provided from pediatric to adult health care for children with special health care needs at FQHCs using the Six Core Elements of Health Care. Methods: A phenomenological approach was used to recruit and interview ten (10) health leaders from FQHCs. The participants were recruited through this letter sent to the Mid-Atlantic Association of Community Health Center. The researchers-initiated contact with the key informant to introduce them to the study. After consent was obtained, demographic information collected, and interviews were scheduled. During the semi-structured interview session, the key informant was asked questions related to their knowledge about the transition from pediatric to adult health care. Each interview lasted approximately 20 minutes, and analysis using ATLAS.ti version 8. Results: Ten (n=10) leaders participated in the study, of which three (n=3) were males and seven (n=7) females. Three main themes identified were Education and Training, Barriers to transitional practices, and Organizational Infrastructure hurdles. Discussion and Conclusion: Our current study finds that healthcare transition practices in FQHCs are not aligned with the six core elements of healthcare transition. Structured health care transition is likely when leadership and resources are accessible to achieve support for the required responsibilities
Coupling Non-Gravitational Fields with Simplicial Spacetimes
The inclusion of source terms in discrete gravity is a long-standing problem.
Providing a consistent coupling of source to the lattice in Regge Calculus (RC)
yields a robust unstructured spacetime mesh applicable to both numerical
relativity and quantum gravity. RC provides a particularly insightful approach
to this problem with its purely geometric representation of spacetime. The
simplicial building blocks of RC enable us to represent all matter and fields
in a coordinate-free manner. We provide an interpretation of RC as a discrete
exterior calculus framework into which non-gravitational fields naturally
couple with the simplicial lattice. Using this approach we obtain a consistent
mapping of the continuum action for non-gravitational fields to the Regge
lattice. In this paper we apply this framework to scalar, vector and tensor
fields. In particular we reconstruct the lattice action for (1) the scalar
field, (2) Maxwell field tensor and (3) Dirac particles. The straightforward
application of our discretization techniques to these three fields demonstrates
a universal implementation of coupling source to the lattice in Regge calculus.Comment: 10 pages, no figures, Latex, fixed typos and minor corrections
Transient intensity changes of cosmic rays beyond the heliospheric termination shock as observed at Voyager 1
This paper continues our studies of temporal variations of cosmic rays beyond the heliospheric termination shock (HTS) using Voyager 1 (V1) data when V1 was beyond 94 AU. This new study utilizes cosmic ray protons and electrons of several energies. Notable transient decreases of 5–50% are observed in galactic cosmic ray nuclei and electrons at V1 shortly after similar decreases are observed at Voyager 2 (V2) still inside the HTS. These decreases at V1 appear to be related to the large solar events in September 2005 and December 2006 and the resulting outward moving interplanetary shock. These two large interplanetary shocks were the largest observed at V2 after V1 crossed the HTS at the end of 2004. They were observed at V2 just inside the HTS at 2006.16 and 2007.43 providing timing markers for V1. From the timing of the intensity decreases observed at V1 as the shocks first reach the HTS and then later reach V1 itself, we can estimate the shock speed beyond the HTS to be between 240 and 300 km s^(−1) in both cases. From the timing of the decreases observed when the shock first reaches the HTS and then several months later encounters the heliopause, we can estimate the heliosheath thickness to be 31 ± 4 and 37 ± 6 AU, respectively, for the two sequences of three decreases seen at V1. These values, along with the distances to the HTS that are determined, give distances from the Sun to the heliopause of 121 ± 4 and 124 ± 6 AU, respectively
Quark-Lepton Symmetry In Five Dimensions
We construct a complete five dimensional Quark-Lepton symmetric model, with
all fields propagating in the bulk. The extra dimension forms an orbifold with the zero mode fermions corresponding to standard model
quarks localised at one fixed point. Zero modes corresponding to
left(right)-chiral leptons are localised at (near) the other fixed point. This
localisation pattern is motivated by the symmetries of the model. Shifting the
right-handed neutrinos and charged leptons slightly from the fixed point
provides a new mechanism for understanding the absence of relations of the type
or in Quark-Lepton symmetric models. Flavour changing
neutral currents resulting from Kaluza Klein gluon exchange, which typically
arise in the quark sector of split fermion models, are suppressed due to the
localisation of quarks at one point. The separation of quarks and leptons in
the compact extra dimension also acts to suppress the proton decay rate. This
permits the extra dimension to be much larger than that obtained in a previous
construct, with the bound TeV obtained.Comment: 12 pages, references added to match published versio
At Voyager 1 Starting on about August 25, 2012 at a Distance of 121.7 AU From the Sun, a Sudden Disappearance of Anomalous Cosmic Rays and an Unusually Large Sudden Increase of Galactic Cosmic Ray H and He Nuclei and Electron Occurred
At the Voyager 1 spacecraft in the outer heliosphere, after a series of
complex intensity changes starting at about May 8th, the intensities of both
anomalous cosmic rays (ACR) and galactic cosmic rays (GCR) changed suddenly and
decisively on August 25th (121.7 AU from the Sun). The ACR started the
intensity decrease with an initial e-folding rate of intensity decrease of ~1
day. Within a matter of a few days, the intensity of 1.9-2.7 MeV protons and
helium nuclei had decreased to less than 0.1 of their previous value and after
a few weeks, corresponding to the outward movement of V1 by ~0.1 AU, these
intensities had decreased by factors of at least 300-500 and are now lower than
most estimates of the GCR spectrum for these lower energies and also at higher
energies. The decrease was accompanied by large rigidity dependent anisotropies
in addition to the extraordinary rapidity of the intensity changes. Also on
August 25th the GCR protons, helium and heavier nuclei as well as electrons
increased suddenly with the intensities of electrons reaching levels ~30-50%
higher than observed just one day earlier. This increase for GCR occurred over
~1 day for the lowest rigidity electrons, and several days for the higher
rigidity nuclei of rigidity ~0.5-1.0 GV. After reaching these higher levels the
intensities of the GCR of all energies from 2 to 400 MeV have remained
essentially constant with intensity levels and spectra that may represent the
local GCR. These intensity changes will be presented in more detail in this,
and future articles, as this story unfolds.Comment: 13 Pages, 5 Figure
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