550 research outputs found
Space processing float zone thermal analysis
Thermal analysis (BETA) computer program adaptations were prepared to analyze phase change histories in crystal specimens. The first program (BETA-CYL) treats right circular cylinder configurations and the second, more general, program (BETA-BOR) treats a generalized body-of-revolution configuration. A series of computer runs were made for silicon material to determine boundary conditions which produce flat solidification interfaces while, at the same time, minimizing peak temperatures in the molten zone. Flat solidification interfaces are a goal believed by some investigators to be required to produce high quality semiconductor materials. The thermal effects of convection in a molten zone were examined and found to be negligible in comparison to the conduction heat transfer of the melt
A Far-UV Variability Survey of the Globular Cluster M80
We have searched for variable sources in the core region of M80, using far
ultra-violet data taken with the Advanced Camera for Surveys on board the
Hubble Space Telescope. We found three sources that exhibit strong signs of
variability in our data. Among these is source TDK1, which we believe to be an
RR Lyrae star that reached maximum brightness during our observations. The
light curve shows a >3 mag FUV brightening over the course of ~5 hours, with an
estimated peak brightness of ~16.7 mag, followed by a decrease to ~20 mag.
Archival optical data obtained with WFPC2 confirm that TDK1 is variable in all
wavebands. TDK1's SED is reasonably fit by a star with temperature T(eff)=6700K
and radius R=4.2R(sun), consistent with the suggestion that it is an RR Lyrae.
Based on the photometric and variability characteristics of the other two
variables, we suggest that TDK2 is likely to be an SX Phoenicis star with ~55
minutes period, and TDK3 is likely another RR Lyrae. Finally, we briefly
discuss the FUV counterparts to two previously known variables in M80, the
classical nova T Sco and the dwarf nova DN1.Comment: 12 pages, 9 figures and 3 tables. Accepted for publication in MNRAS
High resolution spatial modelling of greenhouse gas emissions from land use change to energy crops in the UK
We implemented a spatial application of a previously evaluated model of soil GHG emissions, ECOSSE, in the United Kingdom to examine the impacts to 2050 of land-use transitions from existing land use, rotational cropland, permanent grassland or woodland, to six bioenergy crops; three ‘first-generation’ energy crops: oilseed rape, wheat and sugar beet, and three ‘second-generation’ energy crops: Miscanthus, short rotation coppice willow (SRC) and short rotation forestry poplar (SRF). Conversion of rotational crops to Miscanthus, SRC and SRF and conversion of permanent grass to SRF show beneficial changes in soil GHG balance over a significant area. Conversion of permanent grass to Miscanthus, permanent grass to SRF and forest to SRF shows detrimental changes in soil GHG balance over a significant area. Conversion of permanent grass to wheat, oilseed rape, sugar beet and SRC and all conversions from forest show large detrimental changes in soil GHG balance over most of the United Kingdom, largely due to moving from uncultivated soil to regular cultivation. Differences in net GHG emissions between climate scenarios to 2050 were not significant. Overall, SRF offers the greatest beneficial impact on soil GHG balance. These results provide one criterion for selection of bioenergy crops and do not consider GHG emission increases/decreases resulting from displaced food production, bio-physical factors (e.g. the energy density of the crop) and socio-economic factors (e.g. expenditure on harvesting equipment). Given that the soil GHG balance is dominated by change in soil organic carbon (SOC) with the difference among Miscanthus, SRC and SRF largely determined by yield, a target for management of perennial energy crops is to achieve the best possible yield using the most appropriate energy crop and cultivar for the local situation
Spectroscopic Target Selection in the Sloan Digital Sky Survey: The Quasar Sample
We describe the algorithm for selecting quasar candidates for optical
spectroscopy in the Sloan Digital Sky Survey. Quasar candidates are selected
via their non-stellar colors in "ugriz" broad-band photometry, and by matching
unresolved sources to the FIRST radio catalogs. The automated algorithm is
sensitive to quasars at all redshifts lower than z=5.8. Extended sources are
also targeted as low-redshift quasar candidates in order to investigate the
evolution of Active Galactic Nuclei (AGN) at the faint end of the luminosity
function. Nearly 95% of previously known quasars are recovered (based on 1540
quasars in 446 square degrees). The overall completeness, estimated from
simulated quasars, is expected to be over 90%, whereas the overall efficiency
(quasars:quasar candidates) is better than 65%. The selection algorithm targets
ultraviolet excess quasars to i^*=19.1 and higher-redshift (z>3) quasars to
i^*=20.2, yielding approximately 18 candidates per square degree. In addition
to selecting ``normal'' quasars, the design of the algorithm makes it sensitive
to atypical AGN such as Broad Absorption Line quasars and heavily reddened
quasars.Comment: 62 pages, 15 figures (8 color), 8 tables. Accepted by AJ. For a
version with higher quality color figures, see
http://archive.stsci.edu/sdss/quasartarget/RichardsGT_qsotarget.preprint.p
Environmental variables, habitat discontinuity and life history shaping the genetic structure of Pomatoschistus marmoratus
Coastal lagoons are semi-isolated ecosystems
exposed to wide fluctuations of environmental conditions
and showing habitat fragmentation. These features may
play an important role in separating species into different
populations, even at small spatial scales. In this study, we
evaluate the concordance between mitochondrial (previous
published data) and nuclear data analyzing the genetic
variability of Pomatoschistus marmoratus in five localities,
inside and outside the Mar Menor coastal lagoon (SE
Spain) using eight microsatellites. High genetic diversity
and similar levels of allele richness were observed across
all loci and localities, although significant genic and
genotypic differentiation was found between populations
inside and outside the lagoon. In contrast to the FST values
obtained from previous mitochondrial DNA analyses
(control region), the microsatellite data exhibited significant
differentiation among samples inside the Mar Menor
and between lagoonal and marine samples. This pattern
was corroborated using Cavalli-Sforza genetic distances.
The habitat fragmentation inside the coastal lagoon and
among lagoon and marine localities could be acting as a
barrier to gene flow and contributing to the observed
genetic structure. Our results from generalized additive
models point a significant link between extreme lagoonal
environmental conditions (mainly maximum salinity) and
P. marmoratus genetic composition. Thereby, these environmental
features could be also acting on genetic structure
of coastal lagoon populations of P. marmoratus favoring
their genetic divergence. The mating strategy of P. marmoratus
could be also influencing our results obtained from
mitochondrial and nuclear DNA. Therefore, a special
consideration must be done in the selection of the DNA
markers depending on the reproductive strategy of the
species
Cerebral oximetry during cardiac arrest : a multicenter study of neurologic outcomes and survival
OBJECTIVES
Cardiac arrest is associated with morbidity and mortality because of cerebral ischemia. Therefore, we tested the hypothesis that higher regional cerebral oxygenation during resuscitation is associated with improved return of spontaneous circulation, survival, and neurologic outcomes at hospital discharge. We further examined the validity of regional cerebral oxygenation as a test to predict these outcomes.
DESIGN
Multicenter prospective study of in-hospital cardiac arrest.
SETTING
Five medical centers in the United States and the United Kingdom.
PATIENTS
Inclusion criteria are as follows: in-hospital cardiac arrest, age 18 years old or older, and prolonged cardiopulmonary resuscitation greater than or equal to 5 minutes. Patients were recruited consecutively during working hours between August 2011 and September 2014. Survival with a favorable neurologic outcome was defined as a cerebral performance category 1-2.
INTERVENTIONS
Cerebral oximetry monitoring.
MEASUREMENTS AND MAIN RESULTS
Among 504 in-hospital cardiac arrest events, 183 (36%) met inclusion criteria. Overall, 62 of 183 (33.9%) achieved return of spontaneous circulation, whereas 13 of 183 (7.1%) achieved cerebral performance category 1-2 at discharge. Higher mean ± SD regional cerebral oxygenation was associated with return of spontaneous circulation versus no return of spontaneous circulation (51.8% ± 11.2% vs 40.9% ± 12.3%) and cerebral performance category 1-2 versus cerebral performance category 3-5 (56.1% ± 10.0% vs 43.8% ± 12.8%) (both p < 0.001). Mean regional cerebral oxygenation during the last 5 minutes of cardiopulmonary resuscitation best predicted the return of spontaneous circulation (area under the curve, 0.76; 95% CI, 0.69-0.83); regional cerebral oxygenation greater than or equal to 25% provided 100% sensitivity (95% CI, 94-100) and 100% negative predictive value (95% CI, 79-100); regional cerebral oxygenation greater than or equal to 65% provided 99% specificity (95% CI, 95-100) and 93% positive predictive value (95% CI, 66-100) for return of spontaneous circulation. Time with regional cerebral oxygenation greater than 50% during cardiopulmonary resuscitation best predicted cerebral performance category 1-2 (area under the curve, 0.79; 95% CI, 0.70-0.88). Specifically, greater than or equal to 60% cardiopulmonary resuscitation time with regional cerebral oxygenation greater than 50% provided 77% sensitivity (95% CI,:46-95), 72% specificity (95% CI, 65-79), and 98% negative predictive value (95% CI, 93-100) for cerebral performance category 1-2.
CONCLUSIONS
Cerebral oximetry allows real-time, noninvasive cerebral oxygenation monitoring during cardiopulmonary resuscitation. Higher cerebral oxygenation during cardiopulmonary resuscitation is associated with return of spontaneous circulation and neurologically favorable survival to hospital discharge. Achieving higher regional cerebral oxygenation during resuscitation may optimize the chances of cardiac arrest favorable outcomes
Computational modelling of NF-κB activation by IL-1RI and its co-receptor TILRR, predicts a role for Cytoskeletal Sequestration of IκBα in inflammatory signalling.
The transcription factor NF-κB (nuclear factor kappa B) is activated by Toll-like receptors and controlled by mechanotransduction and changes in the cytoskeleton. In this study we combine 3-D predictive protein modelling and in vitro experiments with in silico simulations to determine the role of the cytoskeleton in regulation of NF-κB. Simulations used a comprehensive agent-based model of the NF-κB pathway, which includes the type 1 IL-1 receptor (IL-1R1) complex and signalling intermediates, as well as cytoskeletal components. Agent based modelling relies on in silico reproductions of systems through the interactions of its components, and provides a reliable tool in investigations of biological processes, which require spatial considerations and involve complex formation and translocation of regulatory components. We show that our model faithfully reproduces the multiple steps comprising the NF-κB pathway, and provides a framework from which we can explore novel aspects of the system. The analysis, using 3-D predictive protein modelling and in vitro assays, demonstrated that the NF-κB inhibitor, IκBα is sequestered to the actin/spectrin complex within the cytoskeleton of the resting cell, and released during IL-1 stimulation, through a process controlled by the IL-1RI co-receptor TILRR (Toll-like and IL-1 receptor regulator). In silico simulations using the agent-based model predict that the cytoskeletal pool of IκBα is released to adjust signal amplification in relation to input levels. The results suggest that the process provides a mechanism for signal calibration and enables efficient, activation-sensitive regulation of NF-κB and inflammatory responses
Photometric Calibration of the Swift Ultraviolet/Optical Telescope
We present the photometric calibration of the Swift UltraViolet/Optical
Telescope (UVOT) which includes: optimum photometric and background apertures,
effective area curves, colour transformations, conversion factors for count
rates to flux, and the photometric zero points (which are accurate to better
than 4 per cent) for each of the seven UVOT broadband filters. The calibration
was performed with observations of standard stars and standard star fields that
represent a wide range of spectral star types. The calibration results include
the position dependent uniformity, and instrument response over the 1600-8000A
operational range. Because the UVOT is a photon counting instrument, we also
discuss the effect of coincidence loss on the calibration results. We provide
practical guidelines for using the calibration in UVOT data analysis. The
results presented here supersede previous calibration results.Comment: Minor improvements after referees report. Accepted for publication in
MNRA
- …
