533 research outputs found
Correlation between capillary oxygen saturation and small intestinal wall thickness in the equine colic patient
The surgical evaluation of haemorrhagic infarcted intestine and the decision for or against bowel resection require a lot of experience and are subjective. The aim of this prospective, clinical study was to examine the correlation between oxygen saturation and small intestinal wall (IW) thickness, using two objective methods. In 22 colicky horses, the blood flow, oxygen saturation and relative amount of haemoglobin were measured intraoperatively via laser Doppler and white light spectroscopy (O2C, oxygen to see, LEA Medizintechnik) at six measuring points (MPs) in small and large intestines. Furthermore, the IW thickness was measured ultrasonographically. Nine of 22 horses had an increased small IW thickness greater than 4?mm (Freeman 2002, Scharner and others 2002, le Jeune and Whitcomb 2014) at measuring point 1 (MP1) (strangulated segment), four horses had a thickened bowel wall at measuring point 3 (MP3) (poststenotic) and one at measuring point 2 (MP2). The oxygen saturation was 0 at MP1 in six horses, at MP3 in two horses and at MP2 (prestenotic) in one. Oxygen saturation and small IW thickness were independent of each other at MP1 and MP2. At MP3, the two parameters were negatively correlated. In summary, it is not possible to draw conclusions about oxygen saturation based on IW thickness
Loring-Greenough House, North Yard Archaeogeophysics, Jamaica Plain, Massachusetts
An archaeogeophysical survey was carried out in May 2010 using Geonics EM-38 RT and a Malå Ground Penetrating Radar (GPR) system with a 500 MHz antenna over an 28x26 m grid immediately northeast of the Loring-Greenough house in Jamaica Plain, MA. Three major anomalies were identified. These anomalies have not been ground truthed, but they appear to be archaeological features. First, we suggest that there is builders trench just north of the house. Second, we suggest that there could be three east-west garden paths or other landscape features about 30 cm below the surface crossing the entire length of the survey grid. Third, we suggest that there could be a buried foundation or cellar hole 110 cm below the ground surface and 20 m north of the house. We recommend additional archaegeophysics be performed at the Loring-Greenough house, as well as a program of exploratory archaeological investigations with the goal of better understanding the past landscape around the house
Scientific objectives and first results from COMPTEL
The imaging Compton telescope (COMPTEL) is the first imaging telescope in space to explore the MeV gamma ray range. At present it is performing a complete sky survey. In later phases of the mission, selected celestial objects will be studied in more detail. Targets of special interest in the COMPTEL energy range are radio pulsars, X-ray binaries, novae, supernova remnants, molecular clouds, and the interstellar medium within the Milky Way, as well as the nuclei of active galaxies, supernovae, and the diffuse cosmic background radiation in extragalactic space. The first four months of operation demonstrated that COMPTEL basically performs as expected. The Crab is clearly seen at its proper position in the first images of the anticenter region of the Galaxy. The Crab pulsar lightcurve was measured with unprecedented accuracy. The quasar 3C273 was seen for the first time at MeV-energies. Several cosmic bursts within the COMPTEL field of view could be located to an accuracy of about 1 degree. On June 9, 11, and 15, 1991 COMPTEL observed gamma ray (continuum and line) emission from three solar flares. Neutrons were also detected from the June 9 flare. At the present state of analysis, COMPTEL achieves the prelaunch predictions of its sensitivity within a factor of 2. Based on the present performance of COMPTEL, the team is confident that COMPTEL will fulfill its primary mission of surveying and exploring the MeV sky
The Spectral Variability of Cygnus X-1 at MeV Energies
In previous work, we have used data from the first three years of the CGRO
mission to assemble a broad-band -ray spectrum of the galactic black
hole candidate Cygnus X-1. Contemporaneous data from the COMPTEL, OSSE and
BATSE experiments on CGRO were selected on the basis of the hard X-ray flux
(45--140 keV) as measured by BATSE. This provided a spectrum of Cygnus X-1 in
its canonical low X-ray state (as measured at energies below 10 keV), covering
the energy range from 50 keV to 5 MeV. Here we report on a comparison of this
spectrum to a COMPTEL-OSSE spectrum collected during a high X-ray state of
Cygnus X-1 (May, 1996). These data provide evidence for significant spectral
variability at energies above 1 MeV. In particular, whereas the hard X-ray flux
{\it decreases} during the high X-ray state, the flux at energies above 1 MeV
{\it increases}, resulting in a significantly harder high energy spectrum. This
behavior is consistent with the general picture of galactic black hole
candidates having two distinct spectral forms at soft -ray energies.
These data extend this picture, for the first time, to energies above 1 MeV.Comment: 5 pages, 4 figures, to be published in AIP Conf. Proc., "The Fifth
Compton Symposium
Measurements of Gamma-Ray Bursts (GRBs) with Glast
One of the scientific goals of the main instrument of GLAST is the study of
Gamma-Ray Bursts (GRBs) in the energy range from ~20 MeV to ~300 GeV. In order
to extend the energy measurement towards lower energies a secondary instrument,
the GLAST Burst Monitor (GBM), will measure GRBs from ~10 keV to ~25 MeV and
will therefore allow the investigation of the relation between the keV and the
MeV-GeV emission from GRBs over six energy decades. These unprecedented
measurements will permit the exploration of the unknown aspects of the
high-energy burst emission and the investigation of their connection with the
well-studied low-energy emission. They will also provide ne insights into the
physics of GRBs in general. In addition the excellent localization of GRBs by
the LAT will stimulate follow-up observations at other wavelengths which may
yield clues about the nature of the burst sources.Comment: 6 pages, 2 figures, to be published in Baltic Astronomy - Proceedings
of the minisymposium "Physics of Gamma-Ray Bursts", JENAM Conference, August
29-30, 2003, Budapes
COMPTEL observations of the quasar PKS 0528+134 during the first 3.5 years of the CGRO mission
The COMPTEL observations of the blazar-type quasar PKS 0528+134 in the energy
range 0.75 MeV to 30 MeV carried out between April 1991 and September 1994 have
been analyzed. During the first two years PKS 0528+134 was most significantly
detected at energies above 3 MeV. During the last year there is only evidence
for the quasar at energies below 3 MeV indicating a spectral change. The
time-averaged COMPTEL energy spectrum between 0.75 MeV and 30 MeV is well
represented by a power-law shape. Spectra collected from different
observational periods reveal different power-law shapes: a hard state during
flaring observations reported by EGRET, and a soft state otherwise. The
combined simultaneous EGRET and COMPTEL spectra indicate these two spectral
states as well. During low intensisty gamma-ray phases no spectral break is
obvious from the combined COMPTEL and EGRET measurements. For the gamma-ray
flaring phases however, the combined COMPTEL and EGRET data require a spectral
bending at MeV-energies. By fitting broken power-law functions the best-fit
values for the break in photon index range between 0.6 and 1.7, and for the
break energy between ~5 MeV and ~20 MeV. Because the flux values measured by
COMPTEL below 3 MeV in both states are roughly equal, the observations would be
consistent with an additional spectral component showing up during gamma-ray
flaring phases of PKS 0528+134. Such a component could be introduced by e.g. a
high-energy electron-positron population with a low-energy cutoff in their bulk
Lorentz factor distribution. The multiwavelength spectrum of PKS 0528+134 for
gamma-ray flaring phases shows that the major energy release across the entire
electro-magnetic spectrum is measured at MeV-energies.Comment: 10 pages, 8 postscript figures, latex, to appear in: A&A 328, 33
(1997
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