6,318 research outputs found
Patient-maintained sedation for oral surgery using a target-controlled infusion of propofol - a pilot study
OBJECTIVE: To assess the safety and efficacy of a new patient-maintained propofol system for conscious sedation in dentistry. DESIGN: Prospective clinical trial SETTING: Department of Sedation, Glasgow Dental Hospital and School, 2001 SUBJECTS AND METHODS: Patients scheduled for oral surgery with conscious sedation. Exclusions included ASA IV -V, inability to use the handset, opioid use and severe respiratory disease. INTERVENTIONS: Patients were given intravenous propofol to a level of 1.0 microg/ml (reducing from 1.5 microg/ml) using a target controlled infusion system, they then controlled their sedation level by double-clicking a handset which on each activation increased the propofol concentration by 0.2 microg/ml. MAIN OUTCOME MEASURES: Oxygen saturation, patient satisfaction, and surgeon satisfaction. RESULTS: Twenty patients were recruited, 16 female and four male. Nineteen patients completed sedation and treatment successfully. Mean lowest oxygen saturation was 94%. No patients were over-sedated. All patients successfully used the system to maintain a level of sedation adequate for their comfort. Patient and surgeon satisfaction were consistently high. CONCLUSIONS: Initial experience with this novel system has confirmed safety, patient satisfaction and surgeon satisfaction
Antiproton-Hydrogen annihilation at sub-kelvin temperatures
The main properties of the interaction of ultra low-energy antiprotons ( a.u.) with atomic hydrogen are established. They include the
elastic and inelastic cross sections and Protonium (Pn) formation spectrum. The
inverse Auger process () is taken into account in the
framework of an unitary coupled-channels model. The annihilation cross-section
is found to be several times smaller than the predictions made by the black
sphere absorption models. A family of nearthreshold metastable
states is predicited. The dependence of Protonium formation probability on the
position of such nearthreshold S-matrix singularities is analysed. An
estimation for the annihilation cross section is obtained.Comment: latex.tar.gz file, 22 pages, 9 figure
Probing the Spiral Magnetic Phase in 6 nm Textured Erbium using Polarised Neutron Reflectometry
We characterise the magnetic state of highly-textured, sputter deposited erbium for a film of thickness 6 nm. Using polarised neutron reflectometry it is found the film has a high degree of magnetic disorder, and we present some evidence that the films’ local magnetic state is consistent with bulk-like spiral magnetism. This, combined with complementary characterisation techniques, show that thin film erbium is a strong candidate material for incorporation into device structures
Exploratory Study of the X-Ray Properties of Quasars With Intrinsic Narrow Absorption Lines
We have used archival Chandra and XMM-Newton observations of quasars hosting
intrinsic narrow UV absorption lines (intrinsic NALs) to carry out an
exploratory survey of their X-ray properties. Our sample consists of three
intrinsic-NAL quasars and one "mini-BAL" quasar, plus four quasars without
intrinsic absorption lines for comparison. These were drawn in a systematic
manner from an optical/UV-selected sample. The X-ray properties of
intrinsic-NAL quasars are indistinguishable from those of "normal" quasars. We
do not find any excess absorption in quasars with intrinsic NALs, with upper
limits of a few times 10^22 cm^-2. We compare the X-ray and UV properties of
our sample quasars by plotting the equivalent width and blueshift velocity of
the intrinsic NALs and the X-ray spectral index against the "optical-to-X-ray"
slope, alpha-ox. When BAL quasars and other AGNs with intrinsic NALs are
included, the plots suggest that intrinsic-NAL quasars form an extension of the
BAL sequences and tend to bridge the gap between BAL and "normal" quasars.
Observations of larger samples of intrinsic-NAL quasars are needed to verify
these conclusions. We also test two competing scenarios for the location of the
NAL gas in an accretion-disk wind. Our results strongly support a location of
the NAL gas at high latitudes above the disk, closer to the disk axis than the
dense BAL wind. We detect excess X-ray absorption only in Q0014+8118, which
does not host intrinsic NALs. The absorbing medium very likely corresponds to
an intervening system at z=1.1, which also produces strong absorption lines in
the rest-frame UV spectrum of this quasar. In the appendix we discuss the
connection between UV and X-ray attenuation and its effect on alpha-ox.Comment: Accepted by the Astrophysical Journa
Roaring high and low: composition and possible functions of the Iberian stag's vocal repertoire
We provide a detailed description of the rutting vocalisations of free-ranging male Iberian deer (Cervus elaphus hispanicus, Hilzheimer 1909), a geographically isolated and morphologically differentiated subspecies of red deer Cervus elaphus. We combine spectrographic examinations, spectral analyses and automated classifications to identify different call types, and
compare the composition of the vocal repertoire with that of other red deer subspecies. Iberian stags give bouts of roars (and more rarely, short series of barks) that are typically composed of two different types of calls. Long Common Roars are mostly given at the beginning or at the end of the bout, and are characterised by a high fundamental frequency (F0) resulting in poorly defined formant frequencies but a relatively high amplitude. In contrast, Short Common Roars are typically given in the middle or at the end of the bout, and are characterised by a lower F0 resulting in relatively well defined vocal tract resonances, but low amplitude. While we did not identify entirely Harsh Roars (as described in the Scottish red
deer subspecies (Cervus elaphus scoticus), a small percentage of Long Common Roars contained segments of deterministic chaos. We suggest that the evolution of two clearly distinct types of Common Roars may reflect divergent selection pressures favouring either vocal efficiency in high pitched roars or the communication of body size in low-pitched, high spectral density roars highlighting vocal tract resonances. The clear divergence of the Iberian red deer vocal repertoire from those of other documented European red deer populations reinforces the status of this geographical variant as a distinct subspecies
Evidence For The Production Of Slow Antiprotonic Hydrogen In Vacuum
We present evidence showing how antiprotonic hydrogen, the quasistable
antiproton-proton (pbar-p) bound system, has been synthesized following the
interaction of antiprotons with the hydrogen molecular ion (H2+) in a nested
Penning trap environment. From a careful analysis of the spatial distributions
of antiproton annihilation events, evidence is presented for antiprotonic
hydrogen production with sub-eV kinetic energies in states around n=70, and
with low angular momenta. The slow antiprotonic hydrogen may be studied using
laser spectroscopic techniques.Comment: 5 pages with 4 figures. Published as Phys. Rev. Letters 97, 153401
(2006), in slightly different for
Influence of the liquid helium meniscus on neutron reflectometry data
Neutron reflectometry offers a unique opportunity for the direct observation of nano-stratification in 3He-4He mixtures in the ultra-low temperature limit. Unfortunately the results of recent experiments could not be well-modelled on account of a seemingly anomalous variation of reflectivity with momentum transfer. We now hypothesize that this effect is attributable to an optical distortion caused by the liquid’s meniscus near the container wall. The validity of this idea is tested and confirmed through a subsidiary experiment on a D2O sample, showing that the meniscus can significantly distort results if the beam size in the horizontal plane is comparable with, or bigger than, the diameter of the container. The meniscus problem can be eliminated if the beam size is substantially smaller than the diameter of the container, such that reflection takes place only from the flat region of the liquid surface thus excluding the meniscus tails. Practical measures for minimising the meniscus distortion effect are discussed
Dramatic X-ray Spectral Variability of the Broad Absorption Line Quasar PG2112+059
With a 1999 ASCA observation, PG2112+059 became notable as the first Broad
Absorption Line (BAL) quasar found to exhibit a typical radio-quiet quasar
X-ray continuum underlying a large amount of intrinsic absorption. We present a
recent Chandra ACIS-S3 observation of PG2112+059 that demonstrates remarkable
spectral and luminosity variability since that time. In addition to a decrease
in the continuum normalization by a factor of ~3.5, the absorption column
density has apparently increased substantially, and a strong feature in the Fe
K alpha region has appeared. Concurrent HST STIS data compared with archival
HST data from earlier epochs show evidence for variability of the continuum (up
to a factor of ~1.7 in the ultraviolet), and in some absorption features of the
CIV 1549 BAL since 1992; however, the OVI BAL structure is consistent with a
1995 observation. We also present evidence for Ly beta--OVI 1037.62 and Ly
alpha--NV 1242.80 line-locked absorption systems, supporting the assumption
that ultraviolet line pressure is driving the BAL outflow. Whereas ultraviolet
BALs typically exhibit only modest equivalent-width variability over timescales
of years, the dramatic X-ray variability of PG2112+059 suggests that X-ray
spectral variability studies of BAL quasars have great potential for probing
the physics of quasar winds.Comment: 30 pages, 10 figures, uses AASTeX. Accepted for publication in the
Astrophysical Journa
Detection of antihydrogen annihilations with a Si-micro-strip and pure CsI detector
In 2002, the ATHENA collaboration reported the creation and detection of cold
(~15 K) antihydrogen atoms [1]. The observation was based on the complete
reconstruction of antihydrogen annihilations, simultaneous and spatially
correlated annihilations of an antiproton and a positron. Annihilation
byproducts are measured with a cylindrically symmetric detector system
consisting of two layers of double sided Si-micro-strip modules that are
surrounded by 16 rows of 12 pure CsI crystals (13 x 17.5 x 17 mm^3). This paper
gives a brief overview of the experiment, the detector system, and event
reconstruction.
Reference 1. M. Amoretti et al., Nature 419, 456 (2002).Comment: 7 pages, 5 figures; Proceedings for the 8th ICATPP Conference on
Astroparticle, Particle, Space Physics, Detectors and Medical Physics
Applications (Como, Italy October 2003) to be published by World Scientific
(style file included
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