68 research outputs found
The Discovery of an Anomalous X-ray Pulsar in the Supernova Remnant Kes 73
We report the discovery of pulsed X-ray emission from the compact source 1E
1841-045, using data obtained with the Advanced Satellite for Cosmology and
Astrophysics. The X-ray source is located in the center of the small-diameter
supernova remnant (SNR) Kes 73 and is very likely to be the compact
stellar-remnant of the supernova which formed Kes 73. The X-rays are pulsed
with a period of ~ 11.8 s, and a sinusoidal modulation of roughly 30 %. We
interpret this modulation to be the rotation period of an embedded neutron
star, and as such would be the longest spin period for an isolated neutron star
to-date. This is especially remarkable since the surrounding SNR is very young,
at ~ 2000 yr old. We suggest that the observed characteristics of this object
are best understood within the framework of a neutron star with an enormous
dipolar magnetic field, B ~ 8x10^14 G
Ground state correlations and mean-field in O
We use the coupled cluster expansion ( method) to generate the
complete ground state correlations due to the NN interaction. Part of this
procedure is the calculation of the two-body G matrix inside the nucleus in
which it is being used. This formalism is being applied to in a
configuration space of 50 . The resulting ground state wave
function is used to calculate the binding energy and one- and two-body
densities for the ground state of .Comment: 9 pages, 9 figures, LaTe
Anomalous X-ray Pulsars and Soft Gamma-Ray Repeaters in supernova remnants
Important constraints on the properties of the Anomalous X-ray Pulsars (AXPs)
and Soft Gamma-Ray Repeaters (SGRs) can be provided by their associations with
supernova remnants (SNRs). We have made a radio search for SNRs towards the
AXPs RX J170849-400910 and 4U 0142+61 - we find that the former lies near a
possible new SNR with which it is unlikely to be physically associated, but see
no SNR in the vicinity of the latter. We review all claimed pairings between
AXPs and SNRs; the three convincing associations imply that AXPs are young (<
10 000 yr) neutron stars with low projected space velocities (< 500 km/s).
Contrary to previous claims, we find no evidence that the density of the
ambient medium around AXPs is higher than that in the vicinity of radio
pulsars. Furthermore, the non-detection of radio emission from AXPs does not
imply that these sources are radio-silent. We also review claimed associations
between SGRs and SNRs. We find none of these associations to be convincing,
consistent with a scenario in which SGRs and AXPs are both populations of
high-field neutron stars ("magnetars") but in which the SGRs are an older or
longer-lived group of objects than are the AXPs. If the SGR/SNR associations
are shown to be valid, then SGRs must be high-velocity objects and most likely
represent a different class of source to the AXPs.Comment: 13 pages, 3 embedded EPS figures. Minor alterations following
referee's report; no significant changes. Accepted to Ap
Spinal muscular atrophy type II (intermediary) and III (Kugelberg-Welander): evolution of 50 patients with physiotherapy and hydrotherapy in a swimming pool
Observations of Accreting Pulsars
We summarize five years of continuous monitoring of accretion-powered pulsars
with the Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray
Observatory. Our 20-70 keV observations have determined or refined the orbital
parameters of 13 binaries, discovered 5 new transient accreting pulsars,
measured the pulsed flux history during outbursts of 12 transients (GRO
J1744-28, 4U 0115+634, GRO J1750-27, GS 0834-430, 2S 1417-624, GRO J1948+32,
EXO 2030+375, GRO J1008-57, A 0535+26, GRO J2058+42, 4U 1145-619 and A
1118-616), and also measured the accretion torque history of during outbursts
of 6 of those transients whose orbital parameters were also known. We have also
continuously measured the pulsed flux and spin frequency for eight persistently
accreting pulsars (Her X-1, Cen X-3, Vela X-1, OAO 1657-415, GX 301-2, 4U
1626-67, 4U 1538-52, and GX 1+4). Because of their continuity and uniformity
over a long baseline, BATSE observations have provided new insights into the
long-term behavior of accreting magnetic stars. We have found that all
accreting pulsars show stochastic variations in their spin frequencies and
luminosities, including those displaying secular spin-up or spin-down on long
time scales, blurring the conventional distinction between disk-fed and
wind-fed binaries. Pulsed flux and accretion torque are strongly correlated in
outbursts of transient accreting pulsars, but uncorrelated, or even
anticorrelated, in persistent sources.Comment: LaTeX, psfig, 90 pages, 42 figures. To appear in Dec. 1997 ApJS, Vol
113, #
Imaging the boundaries—innovative tools for microscopy of living cells and real-time imaging
Recently, light microscopy moved back into the spotlight, which is mainly due to the development of revolutionary technologies for imaging real-time events in living cells. It is truly fascinating to see enzymes “at work” and optically acquired images certainly help us to understand biological processes better than any abstract measurements. This review aims to point out elegant examples of recent cell-biological imaging applications that have been developed with a chemical approach. The discussed technologies include nanoscale fluorescence microscopy, imaging of model membranes, automated high-throughput microscopy control and analysis, and fluorescent probes with a special focus on visualizing enzyme activity, free radicals, and protein–protein interaction designed for use in living cells
Modulação androgênica e estrogênica na próstata: uma abordagem em modelos experimentais de roedores com enfoque na biologia estrutural
Experimentelle Untersuchungen zum Problem der Störungen des Kohlehydratstoffwechsels bei Diphtherie
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