1,786 research outputs found
A study to determine the value of group teaching to the individual diabetic as he perceives it
Thesis (M.S.)--Boston Universit
New Constraints on the Energetics, Progenitor Mass, and Age of the Supernova Remnant G292.0+1.8 Containing PSR J1124-5916
We present spatially resolved spectroscopy of the supernova remnant (SNR)
G292.0+1.8 with the Chandra X-ray observatory. This SNR contains the 135 ms
pulsar, J1124-5916. We apply non-equilibrium ionization (NEI) models to the
data. By comparing the derived abundances with those predicted from
nucleosynthesis models, we estimate a progenitor mass of 30-40 solar masses. We
also derive the intrinsic parameters of the supernova explosion such as its
energy, the age of the SNR, the blast wave velocity, and the swept-up mass. In
the Sedov interpretation, our estimated SNR age of 2,600 years is close to the
pulsar's characteristic age of 2,900 years. This confirms the pulsar/SNR
association and relaxes the need for the pulsar to have a non-canonical value
for the braking index, a large period at birth or a large transverse velocity.
We discuss the properties of the pulsar wind nebula (PWN) in the light of the
Kennel and Coroniti model and estimate the pulsar wind magnetization parameter.
We also report the first evidence for steepening of the power law spectral
index with increasing radius from the pulsar.Comment: 5 pages, 3 figures. To appear in ApJL, Feb 1 2003 (submitted Oct 9
2002, accepted Dec 19 2002
Cryptogenic invasive Klebsiella pneumoniae liver abscess syndrome
SummaryBackgroundKlebsiella pneumoniae-associated liver abscesses have distinct clinical and epidemiologic features.MethodsWe report the unusual case of an American patient with a K. pneumoniae-associated liver abscess and septic spread to other organs. We additionally present a comprehensive review of K. pneumoniae-associated liver abscess syndromes in adults.ResultsWe identified three distinct K. pneumoniae liver abscess syndromes: the polymicrobial liver abscess, the monomicrobial cryptogenic noninvasive liver abscess, and the monomicrobial cryptogenic invasive K. pneumoniae-associated liver abscess (CIKPLA) syndromes, with distinct clinical, epidemiologic and outcome features. CIKPLA syndrome typically affects diabetic patients, mainly in Southeast Asia, and is complicated by septic spread to other organs.ConclusionsThe community-acquired, monomicrobial, K. pneumoniae-associated liver abscess syndromes that typically occur in the USA are mainly noninvasive and affect Asian or Hispanic persons. However, this report provides an alert that CIKPLA syndrome can occur in North America, and physicians need to be aware of it
Snake venom toxins, unlike smaller antagonists, appear to stabilize a resting state conformation of the nicotinic acetylcholine receptor
AbstractPrevious studies have shown that the pattern and degree of 3-(trifluoromethyl)-3-(m-[125I]iodophenyl)diazirine ([125I]TID) photoincorporation into the nicotinic acetylcholine receptor (nAChR) can be used as a sensitive measure of nAChR conformation. Upon desensitization by prolonged exposure to agonists, certain drugs and detergents, or reconstitution into desensitizing lipids, the levels of [125I]TID incorporation into the subunits of the nAChR are dramatically reduced. In this study, we characterized the effects of the snake venom proteins α-bungarotoxin and α-cobrotoxin, as well as the smaller antagonists tubocurarine and gallamine, on [125I]TID incorporation into the subunits of both partially-purified nAChR in native lipids, or affinity-purified nAChR reconstituted into different combinations of lipids. Unlike all other compounds previously tested, α-bungarotoxin and α-cobrotoxin reproducibly increased the level of [125I]TID incorporation into all four subunits of nAChR reconstituted into dioleoylphosphatidylcholine, dioleoylphosphatidic acid and cholesterol. Gallamine had little or no effect on [125I]TID incorporation at any concentration tested (0.1 μM—5 mM). Tubocurarine had no effect on [125I]TID incorporation at low concentrations, but at higher concentrations reduced the level of [125I]TID labeling. The snake venom proteins may shift the population of nAChR, which exists as a mixture of resting state and desensitized conformations, entirely to the resting state. However, the binding of the snake venom toxins does not appear sufficient to induce the resting state conformation in nAChR which have been desensitized by other means, such as solubilization in desensitizing detergents or reconstitution in desensitizing lipids
The Migration of Amphibian Primordial Germ Cells in the Chick Embryo
A fibrous band of extracellular materials on the chick embryo area pellucida/area opaca border is a preferential migratory pathway for chick embryo primordial germ cells (PGC). This band contains fibronectin, collagen Type I and sulphated glycosaminoglycans. It is known that PGCs from Xenopus laevis interact with fibronectin as they undergo migration in the embryo from their site of origin to the gonads. To establish whether this pathway is species specific in chick embryos it was decided to transplant PGC from Xenopus laevis embryos stage 48 on to chick embryos stage 4 fibrous band. Their rapid migration on this extracellular matrix and their subsequent re-orientation of the basement membrane has been studied by scanning electron microscopy
Are there prehistoric shell middens on Rottwest Island?
In August 1973 a number of different types of shell bed were observed at Rottnest Island. The most massive of these were seen around the lakes at the eastern end of the island and there is no doubt that these are natural marine shell beds. However elsewhere shelly deposits were seen whose origin we could not determine with certainty. A number of midden like lenses of shell were exposed in road sections, particularly along the north side of the island. All of these deposits displayed some of the characteristics of Aboriginal shell middens
Chandra Detection of the X-ray counterpart of the High-magnetic field Radio Pulsar J1119-6127 in the Supernova Remnant G292.2-0.5
We report the Chandra Advanced CCD Imaging Spectrometer detection of the
X-ray counterpart of the high magnetic field, ~1600 year-old, 407 ms radio
pulsar J1119-6127 associated with the supernova remnant G292.2-0.5. The
powerful imaging capability of Chandra also unveiled, for the first time, a
faint 3"x6" pulsar wind nebula (PWN) at energies above ~1.2 keV. The X-ray
emission from the pulsar and its associated nebula is well described by an
absorbed power law model with a photon index of 2.2 (1.9-2.8). The
corresponding 0.5-10 keV unabsorbed X-ray luminosity is 5.5(2.2-15.5)x10^32
ergs/s (at 6 kpc). When compared to two other pulsars with similar spin and
magnetic properties, J1119-6127 stands out as being the least efficient at
turning rotational kinetic energy into X-ray emission. This study shows that
high magnetic field radio pulsars can be significant X-ray emitters and Chandra
is needed to study the emission properties of the pulsars and associated faint
PWNe.Comment: 6 pages, 5 figures. To appear in ApJL July 10 2003 (submitted April
10 2003, accepted May 22 2003
Cross-linguistic study of vocal pathology: perceptual features of spasmodic dysphonia in French-speaking subjects
Clinical characterisation of Spasmodic Dysphonia of the adductor type (SD) in French speakers by Klap and colleagues (1993) appears to differ from that of SD in English. This perceptual analysis aims to describe the phonetic features of French SD. A video of 6 French speakers with SD supplied by Klap and colleagues was analysed for frequency of phonatory breaks, pitch breaks, harshness, creak, breathiness and falsetto voice, rate of production, and quantity of speech output. In contrast to English SD, the French speaking SD patients demonstrated no evidence pitch breaks, but phonatory breaks, harshness and breathiness were prominent features. This verifies the French authors’ (1993) clinical description. These findings suggest that phonetic properties of a specific language may affect the manifestation of pathology in neurogenic voice disorders
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