2,069 research outputs found
Studies of the Diffuse Interstellar Bands. III. HD 183143
Echelle spectra of HD 183143 [B7Iae, E(B-V) = 1.27] were obtained on three
nights, at a resolving power R = 38,000 and with a signal-to-noise ratio ~1000
at 6400 A in the final, combined spectrum. A catalog is presented of 414
diffuse interstellar bands (DIBs) measured between 3900 and 8100 A in this
spectrum. The central wavelengths, the widths (FWHM), and the equivalent widths
of nearly all of the bands are tabulated, along with the minimum uncertainties
in the latter. Among the 414 bands, 135 (or 33%) were not reported in four
previous, modern surveys of the DIBs in the spectra of various stars, including
HD 183143. The principal result of this study is that the great majority of the
bands in the catalog are very weak and fairly narrow. Typical equivalent widths
amount to a few mA, and the bandwidths (FWHM) are most often near 0.7 A. No
preferred wavenumber spacings among the 414 bands are identified which could
provide clues to the identities of the large molecules thought to cause the
DIBs. At generally comparable detection limits in both spectra, the population
of DIBs observed toward HD 183143 is systematically redder, broader, and
stronger than that seen toward HD 204827 (Paper II). In addition, interstellar
lines of C2 molecules have not been detected toward HD 183143, while a very
high value of N(C2)/E(B-V) is observed toward HD 204827. Therefore, either the
abundances of the large molecules presumed to give rise to the DIBs, or the
physical conditions in the absorbing clouds, or both, must differ significantly
between the two cases.Comment: Additional data and figures available at http://dibdata.org. To
appear as Astrophysical Journal, 705, 32-45 (Nov. 1, 2009
Mutations of the mitochondrial ND1 gene as a cause of MELAS
Copyright © 2004 by the BMJ Publishing Group Ltd. All rights reserved. BMJ JournalsD. M. Kirby, R. McFarland, A. Ohtake, C. Dunning, M. T. Ryan, C. Wilson, D. Ketteridge, D. M. Turnbull, D. R. Thorburn, R. W. Taylo
Detailed Analysis of Nearby Bulgelike Dwarf Stars II. Lithium Abundances
Li abundances are derived for a sample of bulgelike stars with isochronal
ages of 10-11 Gyr. These stars have orbits with pericentric distances, Rp, as
small as 2-3 kpc and Zmax < 1 kpc. The sample comprises G and K dwarf stars in
the metallicity range -0.80<[Fe/H]< +0.40. Few data of Li abundances in old
turn-off stars (> 4.5 Gyr) within the present metallicity range are available.
M67 (4.7 Gyr) and NGC 188 (6 Gyr) are the oldest studied metal-rich open
clusters with late-type stars. Li abundances have also been studied for few
samples of old metal-rich field stars. In the present work a high dispersion in
Li abundances is found for bulgelike stars for all the metallicity range,
comparable with values in M67. The role of metallicity and age on a Li
depletion pattern is discussed. The possible connection between Li depletion
and oxygen abundance due to atmospheric opacity effects is investigated.Comment: 9 pages, 7 figure
Diagnosis of pancreaticobiliary malignancy by detection of minichromosome maintenance protein 5 in biliary brush cytology
Background: Biliary brush cytology is the standard method of evaluating biliary strictures, but is insensitive at detecting malignancy. In pancreaticobiliary cancer minichromosome maintenance replication proteins (MCM 2–7) are dysregulated in the biliary epithelium and MCM5 levels are elevated in bile samples. This study aimed to validate an immunocolorimetric ELISA assay for MCM5 as a pancreaticobiliary cancer biomarker in biliary brush samples.
methods: Biliary brush specimens were collected prospectively at ERCP from patients with a biliary stricture. Collected samples were frozen at −80 °C. The supernatant was washed and lysed cells incubated with HRP-labelled anti-MCM5 mouse monoclonal antibody. Test positivity was determined by optical density absorbance. Patients underwent biliary brush cytology or additional investigations as per clinical routine.
results: Ninety-seven patients were included in the study; 50 had malignant strictures. Median age was 65 years (range 21–94) and 51 were male. Compared with final diagnosis the MCM5 assay had a sensitivity for malignancy of 65.4% compared with 25.0% for cytology. In the 72 patients with paired MCM5 assay and biliary brush cytology, MCM5 demonstrated an improved sensitivity (55.6% vs 25.0%; P=0.0002) for the detection of malignancy.
conclusions: Minichromosome maintenance replication protein5 is a more sensitive indicator of pancreaticobiliary malignancy than standard biliary brush cytology
Limits on the Boron Isotopic Ratio in HD 76932
Data in the 2090 A B region of HD 76932 have been obtained at high S/N using
the HST GHRS echelle at a resolution of 90,000. This wavelength region has been
previously identified as a likely candidate for observing the B11/B10 isotopic
splitting.
The observations do not match a calculated line profile extremely well at any
abundance for any isotopic ratio. If the B abundance previously determined from
observations at 2500 A is assumed, the calculated line profile is too weak,
indicating a possible blending line. Assuming that the absorption at 2090 A is
entirely due to boron, the best-fit total B abundance is higher than but
consistent with that obtained at 2500 A, and the best-fit isotopic ratio
(B11/B10) is in the range ~10:1 to ~4:1. If the absorption is not entirely due
to B and there is an unknown blend, the best-fit isotopic ratio may be closer
to 1:1. Future observations of a similar metal-poor star known to have
unusually low B should allow us to distinguish between these two possibilities.
The constraints that can be placed on the isotopic ratio based on comparisons
with similar observations of HD 102870 and HD 61421 (Procyon) are also
discussed.Comment: Accepted for Nov 1998 Ap
Pharmacological interventions for primary sclerosing cholangitis: an attempted network meta-analysis.
BACKGROUND: Primary sclerosing cholangitis is a chronic cholestatic liver disease that is associated with both hepatobiliary and colorectal malignancies, which can result in liver cirrhosis and its complications. The optimal pharmacological treatment for patients with primary sclerosing cholangitis remains controversial. OBJECTIVES: To assess the comparative benefits and harms of different pharmacological interventions in people with primary sclerosing cholangitis by performing a network meta-analysis, and to generate rankings of available pharmacological interventions according to their safety and efficacy. Given that it was not possible to assess whether potential effect modifiers were similar across comparisons, we did not perform the network meta-analysis but instead used standard Cochrane methods.When trials begin to provide an adequate description of potential effect modifiers, we will attempt to conduct network meta-analysis. SEARCH METHODS: We searched CENTRAL, MEDLINE, Embase, Science Citation Index - Expanded, the WHO International Clinical Trials Registry Platform, and randomised controlled trials registers until February 2017 to identify randomised clinical trials (RCT) on pharmacological interventions for primary sclerosing cholangitis. SELECTION CRITERIA: We included only RCTs, irrespective of language, blinding, or publication status, in which participants were given a diagnosis of primary sclerosing cholangitis. We excluded trials that included previously liver-transplanted participants. We considered any of various pharmacological interventions compared with one other or with placebo. We excluded trials that compared different doses of various pharmacological interventions or that reported different treatment durations, except for ursodeoxycholic acid (UDCA). As UDCA is the drug most commonly investigated for primary sclerosing cholangitis, we performed a second analysis in which we stratified the dose of UDCA. DATA COLLECTION AND ANALYSIS: We calculated the odds ratio and the rate ratio with 95% confidence intervals (CIs) using both fixed-effect and random-effects models based on available-participant analysis with Review Manager. We assessed risk of bias according to Cochrane, controlled risk of random errors with Trial Sequential Analysis, and assessed the quality of the evidence using GRADE. MAIN RESULTS: We identified 22 RCTs in which 1211 participants were randomised to 13 different interventions. Most were placebo-controlled trials. Trials had few restrictions apart from an established diagnosis of primary sclerosing cholangitis, evidence of cholestasis, absence of decompensated liver disease, and absence of malignancy. However, some trials included symptomatic participants only, and others included both symptomatic and asymptomatic participants. A total of 11 RCTs (706 participants) provided data for one or more outcomes. The period of follow-up ranged from three months to three years in most trials. Only three trials reported follow-up longer than three years. Investigators found no evidence of differences in important clinical benefits such as reduction in mortality at maximal follow-up and improvement in health-related quality of life. Primary outcomes Mortality: Effect estimates: colchicine versus placebo: odds ratio 0.44, 95% CI 0.04 to 5.07, participants = 84, one trial; penicillamine versus placebo: odds ratio 1.18, 95% CI 0.39 to 3.58, participants = 70, one trial; steroids versus placebo: odds ratio 3.00, 95% CI 0.10 to 90.96, participants = 11, one trial; ursodeoxycholic acid versus placebo: odds ratio 1.51, 95% CI 0.63 to 3.63, participants = 348, two trials, I2 = 0%; vancomycin versus placebo: not estimable because no events in either group, participants = 29, one trial. Serious adverse events (proportion): Effect estimates: infliximab versus placebo: odds ratio not estimable (because of zero events in both arms), participants = 7, one trial; steroids versus placebo: odds ratio 20.00, 95% CI 0.93 to 429.90, participants = 11, one trial; vancomycin versus placebo: not estimable because no events in either group, participants = 29, one trial. Serious adverse events (number): Effect estimates: infliximab versus placebo: rate ratio 0.80, 95% CI 0.02 to 40.44, participants = 7, one trial; penicillamine versus placebo: rate ratio 13.60, 95% CI 0.78 to 237.83, participants = 70, one trial; steroids versus placebo: rate ratio 3.32, 95% CI 0.71 to 15.62, participants = 11, one trial. Adverse events (proportion): Effect estimates: steroids versus placebo: odds ratio 20.00, 95% CI 0.93 to 429.90, participants = 11, one trial; ursodeoxycholic acid versus placebo: odds ratio 1.22, 95% CI 0.68 to 2.17, participants = 198, one trial; vancomycin versus placebo: not estimable because no events in either group, participants = 29, one trial. Adverse events (number): Effect estimates: cyclosporin versus placebo: rate ratio 2.64, 95% CI 0.99 to 7.03, participants = 26, one trial; steroids versus placebo: rate ratio 3.32, 95% CI 0.71 to 15.62, participants = 11, one trial; ursodeoxycholic acid plus metronidazole versus ursodeoxycholic acid: rate ratio 2.36, 95% CI 0.98 to 5.71, participants = 71, one trial. Health-related quality of life: ursodeoxycholic acid versus placebo: mean difference 1.30, 95% CI -5.61 to 8.21, participants = 198, one trial (Short Form (SF)-36 General Health Scale). Secondary outcomes Studies provided no evidence of differences in clinical benefits such as a reduction in the requirement for liver transplantation or a reduction in the incidence proportion of cholangiocarcinoma. One small trial (29 participants) comparing vancomycin versus placebo reported no malignancies, no liver decompensation, and no liver transplantation in either group after a very short follow-up period of 12 weeks after treatment. None of the remaining trials clearly reported other clinical benefits such as decreased development of all malignancies, colorectal cancer, liver decompensation, time to liver decompensation, time to liver transplantation, or requirement for cholecystectomy to allow comparisons between different interventions. SOURCE OF FUNDING: Fifteen trials reported the source of funding; three were funded by parties without vested interest in results of the trial, and 12 were funded in part or in full by drug companies. AUTHORS' CONCLUSIONS: Evidence is currently insufficient to show differences in effectiveness measures such as mortality, health-related quality of life, cirrhosis, or liver transplantation between any active pharmacological intervention and no intervention. However, trials were at high risk of bias and included small numbers of participants, had short follow-up periods, and reported few clinical outcomes. An urgent need exists to identify an effective medical treatment for primary sclerosing cholangitis through well-designed RCTs with adequate follow-up that aim to identify differences in outcomes important to people with primary sclerosing cholangitis
BBN and the Primordial Abundances
The relic abundances of the light elements synthesized during the first few
minutes of the evolution of the Universe provide unique probes of cosmology and
the building blocks for stellar and galactic chemical evolution, while also
enabling constraints on the baryon (nucleon) density and on models of particle
physics beyond the standard model. Recent WMAP analyses of the CBR temperature
fluctuation spectrum, combined with other, relevant, observational data, has
yielded very tight constraints on the baryon density, permitting a detailed,
quantitative confrontation of the predictions of Big Bang Nucleosynthesis with
the post-BBN abundances inferred from observational data. The current status of
this comparison is presented, with an emphasis on the challenges to astronomy,
astrophysics, particle physics, and cosmology it identifies.Comment: To appear in the Proceedings of the ESO/Arcetri Workshop on "Chemical
Abundances and Mixing in Stars in the Milky Way and its Satellites", eds., L.
Pasquini and S. Randich (Springer-Verlag Series, "ESO Astrophysics Symposia"
Palliative care for cirrhosis: a UK survey of health professionals' perceptions, current practice and future needs
Objective: To determine the knowledge and practice patterns of a UK cohort of relevant healthcare professionals (HCPs) about delivering palliative care in cirrhosis, and to inform priorities for future research. / Design: An on-line questionnaire survey with closed and open responses. / Setting: HCPs identified from the mailing list of special interest groups in hepatology and gastroenterology (liver), general practice and specialist palliative care (SPC) across the UK. / Results: Of the 6181 potential contacts identified, 517 HCPs responded. Most believed a role exists for SPC in caring for people with cirrhosis, but many SPC HCPs felt ill prepared to provide good care to those facing death. Further training was needed in managing liver-related symptoms, symptom control and end of life issues. All HCP groups wished to increase community provision of palliative care support, but many general practitioners felt unable to manage advanced cirrhosis in the community. There were differences in the optimal trigger for SPC referral with liver HCPs less likely to refer at symptom deterioration. Prognostication, symptom management and service configuration were key areas identified for future research. / Conclusions: All who responded acknowledged the role of SPC in caring for those dying with cirrhosis and need for further training to improve confidence and enable joint working between SPC, general practice and liver teams. Low response rates make it difficult to generalise these findings, which require further validation
Effect of Neutrino Heating on Primordial Nucleosynthesis
We have modified the standard code for primordial nucleosynthesis to include
the effect of the slight heating of neutrinos by annihilations. There
is a small, systematic change in the He yield, , which is insensitive to the value of the baryon-to-photon ratio
for 10^{-10}\la \eta \la 10^{-9}. We also find that the
baryon-to-photon ratio decreases by about 0.5\% less than the canonical factor
of 4/11 because some of the entropy in pairs is transferred to
neutrinos. These results are in accord with recent analytical estimates.Comment: 14 pages/4 Figs (upon request
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