74 research outputs found
Observations of millisecond X-ray pulsars
I present an observational review of the five accretion-driven millisecond
X-ray pulsars currently known, focusing on the results obtained with the Rossi
X-ray Timing Explorer (RXTE) satellite. A prominent place in this review is
given to the first such system discovered, SAX J1808.4-3658. Currently four
outbursts have been detected from this source, three of which have been studied
using RXTE. This makes this source the best studied example of all
accretion-driven millisecond pulsars. Its October 2002 outburst is of
particular interest because of the discovery of kilohertz quasi-periodic
oscillations and burst oscillations during its thermonuclear X-ray bursts. The
other four accreting millisecond pulsars were discovered within the last two
years and only limited results have been published so far. A more extended
review can be found at http://zon.wins.uva.nl/~rudy/admxp/Comment: To appear in the proceedings of "X-ray Timing 2003: Rossi and
Beyond", eds. P. Kaaret, F. K. Lamb, & J. H. Swank (Melvill, NY; AIP). A more
extended version of this review can be found at
http://zon.wins.uva.nl/~rudy/admxp
On the dimension of subspaces with bounded Schmidt rank
We consider the question of how large a subspace of a given bipartite quantum
system can be when the subspace contains only highly entangled states. This is
motivated in part by results of Hayden et al., which show that in large d x
d--dimensional systems there exist random subspaces of dimension almost d^2,
all of whose states have entropy of entanglement at least log d - O(1). It is
also related to results due to Parthasarathy on the dimension of completely
entangled subspaces, which have connections with the construction of
unextendible product bases. Here we take as entanglement measure the Schmidt
rank, and determine, for every pair of local dimensions dA and dB, and every r,
the largest dimension of a subspace consisting only of entangled states of
Schmidt rank r or larger. This exact answer is a significant improvement on the
best bounds that can be obtained using random subspace techniques. We also
determine the converse: the largest dimension of a subspace with an upper bound
on the Schmidt rank. Finally, we discuss the question of subspaces containing
only states with Schmidt equal to r.Comment: 4 pages, REVTeX4 forma
X-ray spectral and timing properties of the 2001 superburst of 4U 1636-536
Preliminary results are reported on the spectral and timing properties of the
spectacular 2001 superburst of 4U 1636-536 as seen by the RXTE/PCA. The
(broad-band) power-spectral and hardness properties during the superburst are
compared to those just before and after the superburst. Not all of the
superburst emission can be fitted by pure black-body radiation. We also
gathered BeppoSAX/WFC and RXTE/ASM data, as well as other RXTE/PCA data,
obtained days to months before and after the superburst to investigate the
normal X-ray burst behavior around the time of the superburst. The first normal
X-ray burst after the 2001 superburst was detected 23 days later. During
inspection of all the RXTE/ASM data we found a third superburst. This
superburst took place on June 26, 1999, which is ~2.9 yrs after the 1996
superburst and ~1.75 yrs before the 2001 superburst. The above findings are the
strongest constraints observed so far on the duration of the cessation of
normal X-ray bursts after a superburst and the superburst recurrence times.Comment: 4 pages, 4 figures,to appear in the proceedings of "X-Ray Timing
2003: Rossi and Beyond", eds. P. Kaaret, F.K. Lamb, & J.H. Swank (Melville,
NY: AIP
The Periods Discovered by RXTE in Thermonuclear Flash Bursts
Oscillations in the X-ray flux of thermonuclear X-ray bursts have been
observed with RXTE from at least 6 low-mass binaries, at frequencies from 330
Hz to 589 Hz. There appear to be preferred relations between the frequencies
present during the bursts and those seen in the persistent flux. The amplitude
of the oscillations can exceed 50 % near burst onset. Except for a systematic
increase in oscillation frequency as the burst progresses, the frequency is
stable. Time resolved spectra track increases in the X-ray emitting area due to
propagation of the burning front over the neutron star surface, as well as
radiation driven expansion of the photosphere. The neutron star mass, radius,
and distance can be inferred when spectra are compared to theoretical
expectations.Comment: 6 pages, 5 figures, to be published in Proceedings of the Symposium
"The Active X-Ray Sky: Results from BeppoSAX and Rossi-XTE", Rome, Italy,
21-24 October, 1997, Nuclear Physics B Proceedings Supplements. Eds. L.
Scarsi, H. Bradt, P. Giommi, and F. Fior
Twelve-year outcomes of watchful waiting versus surgery of mildly symptomatic or asymptomatic inguinal hernia in men aged 50 years and older:a randomised controlled trial
Background: Inguinal hernia belongs to the most common surgical pathology worldwide. Approximately, one third is asymptomatic. The value of watchful waiting (WW) in patients with asymptomatic or mildly symptomatic inguinal hernia has been established in a few randomised controlled trials (RCTs). The aim of this study was to assess long-term outcomes of a RCT comparing WW and elective surgery.Methods: In the original study, men aged ≥50 years with an asymptomatic or mildly symptomatic inguinal hernia were randomly assigned to WW or elective repair. In the present study, the primary outcome was the 12-year crossover rate to surgery, secondary outcomes were time-to-crossover, patient regret, pain, quality of life and incarceration. Dutch Trial Registry: NTR629. Findings: Out of 496 originally analysed patients, 488 (98.4%) were evaluable for chart review (WW: n = 258, surgery: n = 230), and 200 (41.0%) for telephone contact (WW: n = 106, surgery: n = 94) between November 2021 and March 2022 with a median 12 years follow-up (IQR 9–14). After 12 years, the estimated cumulative crossover rate to surgery was 64.2%, which was higher in mildly symptomatic than in asymptomatic patients (71.7% versus 60.4%, HR 1.451, 95% CI: 1.064–1.979). Time-to-crossover was longer in asymptomatic patients (50% after 6.0 years versus 2.0 years, p = 0.019). Patient regret was higher in the WW group (37.7 versus 18.0%, p = 0.002), as well as pain/discomfort (p = 0.031). Quality of life did not differ (p = 0.737). In the WW group, incarceration occurred in 10/255 patients (3.9%). Interpretation: During 12-year follow-up, most WW patients crossed over to surgery, significantly earlier with mildly symptomatic hernia. Considering the relatively low incarceration rate, WW might still be an option in asymptomatic patients with a clear preference and being well-informed about pros and cons.</p
Twelve-year outcomes of watchful waiting versus surgery of mildly symptomatic or asymptomatic inguinal hernia in men aged 50 years and older:a randomised controlled trial
Background: Inguinal hernia belongs to the most common surgical pathology worldwide. Approximately, one third is asymptomatic. The value of watchful waiting (WW) in patients with asymptomatic or mildly symptomatic inguinal hernia has been established in a few randomised controlled trials (RCTs). The aim of this study was to assess long-term outcomes of a RCT comparing WW and elective surgery. Methods: In the original study, men aged ≥50 years with an asymptomatic or mildly symptomatic inguinal hernia were randomly assigned to WW or elective repair. In the present study, the primary outcome was the 12-year crossover rate to surgery, secondary outcomes were time-to-crossover, patient regret, pain, quality of life and incarceration. Dutch Trial Registry: NTR629. Findings: Out of 496 originally analysed patients, 488 (98.4%) were evaluable for chart review (WW: n = 258, surgery: n = 230), and 200 (41.0%) for telephone contact (WW: n = 106, surgery: n = 94) between November 2021 and March 2022 with a median 12 years follow-up (IQR 9–14). After 12 years, the estimated cumulative crossover rate to surgery was 64.2%, which was higher in mildly symptomatic than in asymptomatic patients (71.7% versus 60.4%, HR 1.451, 95% CI: 1.064–1.979). Time-to-crossover was longer in asymptomatic patients (50% after 6.0 years versus 2.0 years, p = 0.019). Patient regret was higher in the WW group (37.7 versus 18.0%, p = 0.002), as well as pain/discomfort (p = 0.031). Quality of life did not differ (p = 0.737). In the WW group, incarceration occurred in 10/255 patients (3.9%). Interpretation: During 12-year follow-up, most WW patients crossed over to surgery, significantly earlier with mildly symptomatic hernia. Considering the relatively low incarceration rate, WW might still be an option in asymptomatic patients with a clear preference and being well-informed about pros and cons. Funding: The initial trial was funded by the Netherlands Organisation for Health Research and Development (ZonMW). This long-term study did not receive funding.</p
The Bank Lending Channel in the Netherlands: the Impact of Monetary Policy on Households and Firms
Item does not contain fulltextRUG/DNB congres Financial Structure, Bank Behaviour and Monetary Policy in the EMU, 5 juni 2000RU Groningen : [S.n.
RXTE/PCA observations reveal fast-transient nature of IGR J17191-2821
On March 3 at 14:31 UTC, the RXTE/PCA had a scan of the Galactic bulge which detected a new source, at a position which is consistent with it being IGR J17191-2821, at an intensity of 10+-1 mCrab (2-10 keV). INTEGRAL's IBIS/IGRI discovered IGR J17191-2821 (Turler et al. 2007, Atel #1021) in an average over the interval March 2, 13:22 to March 4, 05:21 UTC, which included the time or the RXTE scan
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