3,668 research outputs found
An analysis of flight data from aircraft landings with and without the aid of a painted diamond on the same runway
The usefulness of a painted diamond on a runway as a visual aid to perform safe landings of aircraft was studied. Flight data on glideslope intercepts, flight path elevation angles, and touchdown distances were collected and analyzed. It is concluded that an appropriately painted diamond on a runway has the potential of providing glideslope information for the light weight class of general aviation aircraft. This conclusion holds irrespective of the differences in landing techniques used by the pilots
Swords into Ploughshares: Defence Heritage Tourism as the Peaceful Uses of the Artefacts of War
Historic heritage has proved to be one of international tourism\u27s most important primary resources. Such heritage contains an inevitable ideological component. The artefacts and place associations of war are one set of such resources which exercise a growing fascination and attraction for tourist visits. This defence heritage tourism may in practice be a vehicle for a variety of ideological ideas, including, despite the seeming contradiction, international peace and understanding. The distinctive characteristics of the resource, the variety of visitor motives, and the dominant ideologies in presentation will be examined, using North-West European examples. This in turn may lead to the design of policies to use tourism as an instrument for the harnessing of the long history of human conflict as a force for international understanding
Flight test evaluation of an RAF high altitude partial pressure protective assembly
A partial pressure suit was evaluated during tests in an F-104 and F-15 as a protective garment for emergency descents. The garment is an pressure jerkin and modified anti-g suit combined with an oronasal mask. The garment can be donned and doffed at the aircraft to minimize thermal buildup. The oronasal mask was favored by the pilots due to its immobility on the face during high g-loading. The garment was chosen to provide optimum dexterity for the pilot, which is not available in a full pressure suit, while protecting the pilot at altitudes up to 18,288 meters, during a cabin decompression, and subsequent aircraft descent. During cabin decompressions in the F-104 and F-15, cabin pressure altitude was measured at various aircraft angles of attack, Mach numbers, and altitudes to determine the effect of the aerodynamic slipstream on the cabin altitude
The Compact Central Object in Cas A: A Neutron Star with Hot Polar Caps or a Black Hole?
The central pointlike X-ray source of the Cas A supernova remnant was
discovered in the Chandra First Light Observation and found later in the
archival ROSAT and Einstein images. The analysis of these data does not show
statistically significant variability of the source. The power-law fit yields
the photon index 2.6-4.1, and luminosity (2-60)e34 erg/s, for d=3.4 kpc. The
power-law index is higher, and the luminosity lower, than those observed
fromvery young pulsars. One can fit the spectrum equally well with a blackbody
model with T=6-8 MK, R=0.2-0.5 km, L=(1.4-1.9)e33 erg/s. The inferred radii are
too small, and the temperatures too high, for the radiationcould be interpreted
as emitted from the whole surface of a uniformly heated neutron star. Fits with
the neutron star atmosphere models increase the radius and reduce the
temperature, but these parameters are still substantially different from those
expected for a young neutron star. One cannot exclude, however, that the
observed emission originates from hot spots on a cooler neutron star surface.
Because of strong interstellar absorption, the possible low-temperature
component gives a small contribution to the observed spectrum; an upper limit
on the (gravitationally redshifted) surface temperature is < 1.9-2.3 MK.
Amongst several possible interpretations, we favor a model of a strongly
magnetized neutron star with magnetically confined hydrogen or helium polar
caps on a cooler iron surface. Alternatively, the observed radiation may be
interpreted as emitted by a compact object (more likely, a black hole)
accreting from a fossil disk or from a late-type dwarf in a close binary.Comment: 12 pages, 2 figures, submitted to ApJ
Trends in gabapentinoid prescribing in patients with osteoarthritis: a United Kingdom national cohort study in primary care
Summary Objective
To investigate trends in gabapentinoid prescribing in patients with osteoarthritis (OA).
Methods
Patients aged 40 years and over with a new OA diagnosis recorded between 1995 and 2015 were identified in the Clinical Practice Research Datalink and followed to first prescription of gabapentin or pregabalin, or other censoring event. We estimated the crude and age-standardised annual incidence rates of gabapentinoid prescribing, stratified by patient age, sex, geographical region, and time since OA diagnosis, and the proportion of prescriptions attributable to OA, or to other conditions representing licensed and unlicensed indications for a gabapentinoid prescription.
Results
Of 383,680 newly diagnosed OA cases, 35,031 were prescribed at least one gabapentinoid. Irrespective of indication, the annual age-standardised incidence rate of first gabapentinoid prescriptions rose from 1.6 (95% CI: 1.3, 2.0) per 1,000 person-years in 2000, to 27.6 (26.7, 28.4) in 2015, a trend seen across all ages and not explained by length of follow-up. Rates were higher among women, younger patients, and in Northern Ireland, Scotland and the North of England. Approximately 9% of first prescriptions could be attributed to OA, a further 13% to comorbid licensed or unlicensed indications.
Conclusion
Gabapentinoid prescribing in patients with OA increased dramatically between 1995 and 2015. In most cases, diagnostic codes for licensed or unlicensed indications were absent. Gabapentinoid prescribing may be attributable to OA in a significant proportion but evidence for their effectiveness in OA is lacking. Further research to investigate clinical decision making around prescribing these expensive and potentially harmful medicines is recommended
Search for an Near-IR Counterpart to the Cas A X-ray Point Source
We report deep near-infrared and optical observations of the X-ray point
source in the Cassiopeia A supernova remnant, CXO J232327.9+584842. We have
identified a J=21.4 +/- 0.3 mag and Ks=20.5 +/- 0.3 mag source within the
1-sigma error circle, but we believe this source is a foreground Pop II star
with Teff=2600-2800 K at a distance of ~2 kpc, which could not be the X-ray
point source. We do not detect any sources in this direction at the distance of
Cas A, and therefore place 3-sigma limits of R >~ 25 mag, F675W >~ 27.3 mag, J
>~ 22.5 mag and Ks >~ 21.2 mag (and roughly H >~ 20 mag) on emission from the
X-ray point source, corresponding to M_{R} >~ 8.2 mag, M_{F675W} >~ 10.7 mag,
M_{J} >~ 8.5 mag, M_{H} >~ 6.5 mag, and M_{Ks} >~ 8.0 mag, assuming a distance
of 3.4 kpc and an extinction A_{V}=5 mag.Comment: 14 pages, 7 figures. Accepted by Ap
CYLD is a deubiquitinating enzyme that negatively regulates NF-kappaB activation by TNFR family members
Familial cylindromatosis is an autosomal dominant predisposition to tumours of skin appendages called cylindromas. Familial cylindromatosis is caused by mutations in a gene encoding the CYLD protein of previously unknown function1. Here we show that CYLD is a deubiquitinating enzyme that negatively regulates activation of the transcription factor NF-κB by specific tumour-necrosis factor receptors (TNFRs). Loss of the deubiquitinating activity of CYLD correlates with tumorigenesis. CYLD inhibits activation of NF-κB by the TNFR family members CD40, XEDAR and EDAR in a manner that depends on the deubiquitinating activity of CYLD. Downregulation of CYLD by RNA-mediated interference augments both basal and CD40-mediated activation of NF-κB. The inhibition of NF-κB activation by CYLD is mediated, at least in part, by the deubiquitination and inactivation of TNFR-associated factor 2 (TRAF2) and, to a lesser extent, TRAF6. These results indicate that CYLD is a negative regulator of the cytokine-mediated activation of NF-κB that is required for appropriate cellular homeostasis of skin appendages
Upper Limits On Periodic, Pulsed Radio Emission from the X-Ray Point Source in Cassiopeia A
The Chandra X-ray Observatory recently discovered an X-ray point source near
the center of Cassiopeia A, the youngest known Galactic supernova remnant. We
have conducted a sensitive search for radio pulsations from this source with
the Very Large Array, taking advantage of the high angular resolution of the
array to resolve out the emission from the remnant itself. No convincing
signatures of a dispersed, periodic source or of isolated dispersed pulses were
found, whether for an isolated or a binary source. We derive upper limits of 30
and 1.3 mJy at 327 and 1435 MHz for the phase-averaged pulsed flux density from
this source. The corresponding luminosity limits are lower than those for any
pulsar with age less than 10^4 years. The sensitivities of our search to single
pulses were 25 and 1.0 Jy at 327 and 1435 MHz. For comparison, the Crab pulsar
emits roughly 80 pulses per minute with flux densities greater than 100 Jy at
327 MHz and 8 pulses per minute with flux densities greater than 50 Jy at 1435
MHz. These limits are consistent with the suggestion that the X-ray point
source in Cas A adds to the growing number of neutron stars which are not radio
pulsars.Comment: accepted by ApJ Letter
Cell Invasion in Collagen Scaffold Architectures Characterized by Percolation Theory.
The relationship between biological scaffold interconnectivity and cell migration is an important but poorly understood factor in tissue regeneration. Here a scale-independent technique for characterization of collagen scaffold interconnectivity is presented, using a combination of X-ray microcomputed tomography and percolation theory. Confocal microscopy of connective tissue cells reveals this technique as highly relevant for determining the extent of cell invasion.The authors acknowledge financial support from EPSRC, Geistlich Pharma AG and ERC Advanced Grant 320598 3D-E.This is the final version of the article. It first appeared from Wiley at http://dx.doi.org/10.1002/adhm.201500197
The X-ray Source at the Center of the Cassiopeia A Supernova Remnant
We present the first results of an XMM-Newton observation of the central
X-ray source in the Cas A supernova remnant. The spectrum can be fit equally
well with an absorbed steep power law (alpha~3, N_H~1.5x10^22 cm^-2) or with a
bremsstrahlung with temperature kT~2.4 keV and N_H~10^22 cm^-2. A blackbody
model (kT~0.7 keV) gives a slightly worse fit and requires a column density
N_H~5x10^21 cm^-2 and an emitting area with radius ~0.3 km (for d=3.4 kpc). A
search for pulsations for periods longer than 150 ms gave negative results. The
3 sigma upper limits on the pulsed fraction are ~13% for P>0.3 s and ~7% for
P>3 s. The overall properties of the central X-ray source in Cas A are
difficult to explain in terms of a rapidly spinning neutron star with a
canonical magnetic field of ~10^12 G, and are more similar to those of slowly
rotating neutron stars such as the Anomalous X-ray Pulsars.Comment: 15 pages, latex, 3 figures, to appear in The Astrophysical Journal;
Revised version with more details on spectral analysis, fig. 1 and 2 slightly
changed, revised flux value
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