16,590 research outputs found
Study of outgassing and decomposition of Space Shuttle heat protection tiles, fillers and adhesive
A purge and trap technique which was employed to collect and separate the chemicals desorbing from the space shuttle heat protection tiles is described. The instrumentation included a mass spectrometer and gas chromatograph
What do we really know about infants who attend Accident and Emergency departments?
Aims: Accident and Emergency attendances continue to rise. Infants are disproportionately represented. This study examines the clinical reasons infants attend UK Accident and Emergency departments.
Methods: A retrospective review of 6,667 infants aged less than one year attending Accident and Emergency at two district general hospitals in London from 1st April 2009 to 30th March 2010. All infants had been assigned to a diagnostic category by the medical coding department according to National Health Service (NHS) data guidelines, based on the clinical diagnoses stated in the medical records. The Accident and Emergency case notes of a random subsample of 10% of infants in each of the top five recorded diagnostic categories (n = 535) were reviewed in detail and audited against the standard national NHS data set.
Results: The top 5 clinical diagnoses were ‘infectious diseases’, ‘gastrointestinal’, ‘respiratory’, ‘unclassifiable’ and ‘no abnormality detected’ (NAD). A third of infants were originally given a diagnosis of unclassifiable (21.5%) or NAD (11.5%). After detailed case-note review, we were able to reduce this to 9.7% (95% confidence interval (CI): 9.0, 10.4) and 8.8% (95% CI: 8.1, 9.5), respectively.
Conclusion: This study demonstrates the importance of providing a clear clinical diagnosis and coding system for Accident and Emergency attendances and understanding that system fully. This would allow for better informed health service evaluation, planning and research as each of these relies on the interpretation of routine health-care data. Furthermore, the relatively high proportion (10%) of infants attending with no discernible underlying medical abnormality suggests the health needs of a significant proportion of infants attending Accident and Emergency departments may be better addressed by alternative service provision and/or improved education and support to parents
Fabrication of titanium multi-wall Thermal Protection System (TPS) test panel arrays
Several arrays were designed and tested. Tests included vibrational and acoustical tests, radiant heating tests, and thermal conductivity tests. A feasible manufacturing technique was established for producing the protection system panels
On the gravitational wave background from compact binary coalescences in the band of ground-based interferometers
This paper reports a comprehensive study on the gravitational wave (GW)
background from compact binary coalescences. We consider in our calculations
newly available observation-based neutron star and black hole mass
distributions and complete analytical waveforms that include post-Newtonian
amplitude corrections. Our results show that: (i) post-Newtonian effects cause
a small reduction in the GW background signal; (ii) below 100 Hz the background
depends primarily on the local coalescence rate and the average chirp
mass and is independent of the chirp mass distribution; (iii) the effects of
cosmic star formation rates and delay times between the formation and merger of
binaries are linear below 100 Hz and can be represented by a single parameter
within a factor of ~ 2; (iv) a simple power law model of the energy density
parameter up to 50-100 Hz is sufficient to be used
as a search template for ground-based interferometers. In terms of the
detection prospects of the background signal, we show that: (i) detection (a
signal-to-noise ratio of 3) within one year of observation by the Advanced LIGO
detectors (H1-L1) requires a coalescence rate of for binary neutron stars (binary black holes); (ii) this limit on
could be reduced 3-fold for two co-located detectors, whereas the
currently proposed worldwide network of advanced instruments gives only ~ 30%
improvement in detectability; (iii) the improved sensitivity of the planned
Einstein Telescope allows not only confident detection of the background but
also the high frequency components of the spectrum to be measured. Finally we
show that sub-threshold binary neutron star merger events produce a strong
foreground, which could be an issue for future terrestrial stochastic searches
of primordial GWs.Comment: A few typos corrected to match the published version in MNRA
Re-design and fabrication of titanium multi-wall Thermal Protection System (TPS) test panels
The Titanium Multi-wall Thermal Protection System (TIPS) panel was re-designed to incorporate Ti-6-2-4-2 outer sheets for the hot surface, ninety degree side closures for ease of construction and through panel fastness for ease of panel removal. Thermal and structural tests were performed to verify the design. Twenty-five panels were fabricated and delivered to NASA for evaluation at Langley Research Center and Johnson Space Center
Carbamazepine on a carbamazepine monolayer forms unique 1D supramolecular assemblies
High-resolution STM imaging of the structures formed by carbamazepine molecules adsorbed onto a pseudo-ordered carbamazepine monolayer on Au(111) shows the formation of previously unreported 1-dimensional supramolecular assemblies
The Cosmic Origins Spectrograph and the Future of Ultraviolet Astronomy
I describe the capabilities of the Cosmic Origins Spectrograph, scheduled for
May 2009 installation on the Hubble Space Telescope. With a factor-of-ten
increase in far-UV throughput for moderate resolution spectroscopy, COS will
enable a range of scientific programs that study hot stars, AGN, and gas in the
interstellar medium, intergalactic medium, and galactic halos. We also plan a
large-scale HST Spectroscopic Legacy Project for QSO absorption lines, galactic
halos, and AGN outflows. Studies of next-generation telescopes for UV/O
astronomy are now underway, including small, medium, and large missions to fill
the imminent ten-year gap between the end of Hubble and a plausible launch of
the next large mission. Selecting a strategy for achieving these goals will
involve hard choices and tradeoffs in aperture, wavelength, and capability.Comment: To appear in Future Directions in Ultraviolet Astronomy (AIP Conf
Proc
Highly Ionized Envelopes of High Velocity Clouds
We present recent results on highly ionized gas in Galactic High-Velocity
Clouds (HVCs), originally surveyed in OVI (Sembach et al. 2003). In a new
FUSE/HST survey of SiII/III/IV (Shull et al. 2009) toward 37 AGN, we detected
SiIII (lambda 1206.500 A) absorption with a sky coverage fraction 81 +/- 5% (61
HVCs along 30 of 37 high-latitude sight lines). The SiIII (lambda 1206.500 A)
line is typically 4-5 times stronger than OVI (lambda 1031.926 A). The mean HVC
column density of perhaps 10^19 cm^-2 of low-metallicity (0.1 - 0.2 Z_sun)
ionized gas in the low halo. Recent determinations of HVC distances allow us to
estimate a total reservoir of ~10^8 M_sun. Estimates of infall velocities
indicate an infall rate of around 1 M_sun yr^-1, comparable to the
replenishment rate for star formation in the disk. HVCs appear to be sheathed
by intermediate-temperature gas (10^4.0 - 10^4.5 K) detectable in SiIII and
SiIV, as well as hotter gas seen in OVI and other high ions. To prepare for HST
observations of 10 HVC-selected sight lines with the Cosmic Origins
Spectrograph (COS), we compile FUSE/STIS spectra of these ions, plus FeIII,
CIII, CIV, and SIV. Better constraints on the physical properties of HVC
envelopes and careful treatment of HVC kinematics and infall rates should come
from high-quality (S/N ~ 30-40) COS data.Comment: 3 pages, 1 figure, published in Future Directions in Ultraviolet
Spectroscopy, Proceedings of the AIP Conference held October 20-22, 2008 in
Annapolis, Marylan
Contribution of time of day and the circadian clock to the heat stress responsive transcriptome in Arabidopsis.
In Arabidopsis, a large subset of heat responsive genes exhibits diurnal or circadian oscillations. However, to what extent the dimension of time and/or the circadian clock contribute to heat stress responses remains largely unknown. To determine the direct contribution of time of day and/or the clock to differential heat stress responses, we probed wild-type and mutants of the circadian clock genes CCA1, LHY, PRR7, and PRR9 following exposure to heat (37 °C) and moderate cold (10 °C) in the early morning (ZT1) and afternoon (ZT6). Thousands of genes were differentially expressed in response to temperature, time of day, and/or the clock mutation. Approximately 30% more genes were differentially expressed in the afternoon compared to the morning, and heat stress significantly perturbed the transcriptome. Of the DEGs (~3000) specifically responsive to heat stress, ~70% showed time of day (ZT1 or ZT6) occurrence of the transcriptional response. For the DEGs (~1400) that are shared between ZT1 and ZT6, we observed changes to the magnitude of the transcriptional response. In addition, ~2% of all DEGs showed differential responses to temperature stress in the clock mutants. The findings in this study highlight a significant role for time of day in the heat stress responsive transcriptome, and the clock through CCA1 and LHY, appears to have a more profound role than PRR7 and PRR9 in modulating heat stress responses during the day. Our results emphasize the importance of considering the dimension of time in studies on abiotic stress responses in Arabidopsis
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