6,660 research outputs found
Far-UV Emission from Elliptical Galaxies at z=0.55
The restframe UV-to-optical flux ratio, characterizing the ``UV upturn''
phenomenon, is potentially the most sensitive tracer of age in elliptical
galaxies; models predict that it may change by orders of magnitude over the
course of a few Gyr. In order to trace the evolution of the UV upturn as a
function of redshift, we have used the far-UV camera on the Space Telescope
Imaging Spectrograph to image the galaxy cluster CL0016+16 at z=0.55. Our
25''x25'' field includes four bright elliptical galaxies, spectroscopically
confirmed to be passively evolving cluster members. The weak UV emission from
the galaxies in our image demonstrates that the UV upturn is weaker at a
lookback time 5.6 Gyr earlier than our own, as compared to measurements of the
UV upturn in cluster E and S0 galaxies at z=0 and z=0.375. These images are the
first with sufficient depth to demonstrate the fading of the UV upturn expected
at moderate redshifts. We discuss these observations and the implications for
the formation history of galaxies.Comment: 4 pages, Latex. 2 figures. Uses corrected version of emulateapj.sty
and apjfonts.sty (included). Accepted for publication in ApJ Letter
Deaf writers’ application of ASL knowledge to English
Language transfer theory elucidates how first language (L1) knowledge and grammatical features are applied in second language (L2) writing. Deaf and hard of hearing (d/hh) students who use or are developing American Sign Language (ASL) as their L1 may demonstrate use of ASL linguistic features in their writing of English. In this study, we investigated the extent to which 29 d/hh students in grades 6-8 (mean age = 13.2) with diverse ASL exposure incorporated ASL features in their English writing. We also investigated the impact of one year of Strategic and Interactive Writing Instruction (SIWI) to increase students’ metalinguistic knowledge and linguistic competence, and subsequently reduce ASL features in writing. Results indicate that ASL transfer is found in the writings of students with varied L1 experiences, and that SIWI can lead to significant reductions of ASL features in writing. The findings suggest that bilingual literacy programs where there is an emphasis on implicit language competence and metalinguistic knowledge can support d/hh students in the development of written English
Decaying Sterile Neutrinos as a Heating Source in the Milky Way Center
Recent Chandra and Newton observations indicate that there are
two-temperature components ( 8 keV, 0.8 keV) of the diffuse x-rays
emitted from deep inside the center of Milky Way. We show that this can be
explained by the existence of sterile neutrinos, which decay to emit photons
that can be bound-free absorbed by the isothermal hot gas particles in the
center of Milky Way. This model can account for the two-temperature components
naturally as well as the energy needed to maintain the 8 keV temperature
in the hot gas. The predicted sterile neutrino mass is between 16-18 keV.Comment: Accepted by MNRAS with minor correction
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Morale is high in acute inpatient psychiatry
Background: Morale on acute psychiatric wards has been considered to be problematic, and is reported to contribute to low quality patient care.
Aim: To assess the relationship of staff morale to patient, service environment, physical environment, patient routines, conflict, containment, staff demographics, and staff group variables.
Method: A multivariate cross sectional study was undertaken collecting data on morale and other variables on 136 acute admission psychiatric wards in England.
Results: Morale was higher than published comparison samples. Length of time in post was correlated with low morale, and qualified nurses had higher emotional exhaustion but also higher personal accomplishment. The level of verbal abuse on a ward was associated with low morale, as was a higher level of social deprivation among patients. Higher levels of order and organisation correlated with better morale.
Conclusions: Clear policies relating to the management of verbal abuse by patients, high levels of order and organisation, and staff rotation and education, may all support high morale. Acute inpatient psychiatry is generally a happy and rewarding work environment, and identified problems are likely to be due to other factors
Photodissociation of Conformer-Selected Ubiquitin Ions Reveals Site-Specific Cis/Trans Isomerization of Proline Peptide Bonds
Ultraviolet photodissociation (UVPD) of gas-phase proteins has attracted increased attention in recent years. This growing interest is largely based on the fact that, in contrast to slow heating techniques such as collision induced dissociation (CID), the cleavage propensity after absorption of UV light is distributed over the entire protein sequence, which can lead to a very high sequence coverage as required in typical top-down proteomics applications. However, in the gas phase, proteins can adopt a multitude of distinct and sometimes coexisting conformations, and it is not clear how this three-dimensional structure affects the UVPD fragmentation behavior. Using ion mobility–UVPD–mass spectrometry in conjunction with molecular dynamics simulations, we provide the first experimental evidence that UVPD is sensitive to the higher order structure of gas-phase proteins. Distinct UVPD spectra were obtained for different extended conformations of 11+ ubiquitin ions. Assignment of the fragments showed that the majority of differences arise from cis/trans isomerization of one particular proline peptide bond. Seen from a broader perspective, these data highlight the potential of UVPD to be used for the structural analysis of proteins in the gas phas
Far-Ultraviolet Emission from Elliptical Galaxies at z=0.33
We present far-ultraviolet (far-UV) images of the rich galaxy cluster
ZwCl1358.1+6245, taken with the Space Telescope Imaging Spectrograph on board
the Hubble Space Telescope (HST). When combined with archival HST observations,
our data provide a measurement of the UV-to-optical flux ratio in 8 early-type
galaxies at z=0.33. Because the UV flux originates in a population of evolved,
hot, horizontal branch (HB) stars, this ratio is potentially one of the most
sensitive tracers of age in old populations -- it is expected to fade rapidly
with lookback time. We find that the UV emission in these galaxies, at a
lookback time of 3.9 Gyr, is significantly weaker than it is in the current
epoch, yet similar to that in galaxies at a lookback time of 5.6 Gyr. Taken at
face value, these measurements imply different formation epochs for the massive
ellipticals in these clusters, but an alternative explanation is a "floor" in
the UV emission due to a dispersion in the parameters that govern HB
morphology.Comment: 4 pages, Latex. 2 figures. Uses corrected version of emulateapj.sty
and apjfonts.sty (included). Accepted for publication in ApJ Letter
Tackling Exascale Software Challenges in Molecular Dynamics Simulations with GROMACS
GROMACS is a widely used package for biomolecular simulation, and over the
last two decades it has evolved from small-scale efficiency to advanced
heterogeneous acceleration and multi-level parallelism targeting some of the
largest supercomputers in the world. Here, we describe some of the ways we have
been able to realize this through the use of parallelization on all levels,
combined with a constant focus on absolute performance. Release 4.6 of GROMACS
uses SIMD acceleration on a wide range of architectures, GPU offloading
acceleration, and both OpenMP and MPI parallelism within and between nodes,
respectively. The recent work on acceleration made it necessary to revisit the
fundamental algorithms of molecular simulation, including the concept of
neighborsearching, and we discuss the present and future challenges we see for
exascale simulation - in particular a very fine-grained task parallelism. We
also discuss the software management, code peer review and continuous
integration testing required for a project of this complexity.Comment: EASC 2014 conference proceedin
Observation of enhanced rate coefficients in the H + H H + H reaction at low collision energies
The energy dependence of the rate coefficient of the H reaction has been measured in the range of
collision energies between K and
mK. A clear deviation of the rate coefficient from the value expected on the
basis of the classical Langevin-capture behavior has been observed at collision
energies below K, which is attributed to the joint
effects of the ion-quadrupole and Coriolis interactions in collisions involving
ortho-H molecules in the rotational level, which make up 75% of the
population of the neutral H molecules in the experiments. The experimental
results are compared to very recent predictions by Dashevskaya, Litvin, Nikitin
and Troe (J. Chem. Phys., in press), with which they are in agreement.Comment: 14 pages, 3 figure
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