4,014 research outputs found
Eradication therapy for peptic ulcer disease in Helicobacter pylori-positive people
BACKGROUND: Peptic ulcer disease is the cause of dyspepsia in about 10% of people. Ninety-five percent of duodenal and 70% of gastric ulcers are associated with Helicobacter pylori. Eradication of H. pylori reduces the relapse rate of ulcers but the magnitude of this effect is uncertain. This is an update of Ford AC, Delaney B, Forman D, Moayyedi P. Eradication therapy for peptic ulcer disease in Helicobacter pylori-positive patients. Cochrane Database of Systematic Reviews 2006, Issue 2. Art. No.: CD003840. DOI: 10.1002/14651858.CD003840.pub4. OBJECTIVES: To assess the proportion of peptic ulcers healed and the proportion of participants who remained free from relapse with eradication therapy against placebo or other pharmacological therapies in H. pylori-positive people.To assess the proportion of participants that achieved complete relief of symptoms and improvement in quality of life scores.To compare the incidence of adverse effects/drop-outs (total number for each drug) associated with the different treatments.To assess the proportion of participants in whom successful eradication was achieved. SEARCH METHODS: In this update, we identified trials by searching the Cochrane Central Register of Controlled Trials (CENTRAL), Ovid MEDLINE (1950 to March 2016) and Ovid EMBASE (1980 to March 2016). To identify further relevant trials, we handsearched reference lists from trials selected by electronic searching, and published abstracts from conference proceedings from the United European Gastroenterology Week (published in Gut) and Digestive Disease Week (published in Gastroenterology). The search was last updated in March 2016. We contacted members of Cochrane Upper GI and Pancreatic Diseases, and experts in the field and asked them to provide details of outstanding clinical trials and any relevant unpublished materials. SELECTION CRITERIA: We analysed randomised controlled trials of short- and long-term treatment of peptic ulcer disease in H. pylori-positive adults. Participants received at least one week of H. pylori eradication compared with ulcer healing drug, placebo or no treatment. Trials were included if they reported assessment from two weeks onwards. DATA COLLECTION AND ANALYSIS: We collected data on ulcer healing, recurrence, relief of symptoms and adverse effects. We calculated the risk ratio (RR) with 95% confidence intervals (CI) using both fixed-effect and random-effects models with Review Manager software (RevMan 5.3) based on intention-to-treat analysis as far as possible. MAIN RESULTS: A total of 55 trials were included for one or more outcomes for this review.In duodenal ulcer healing, eradication therapy was superior to ulcer healing drug (UHD) (34 trials, 3910 participants, RR of ulcer persisting = 0.66, 95% confidence interval (CI) 0.58 to 0.76; 381/2286 (adjusted proportion: 12.4%) in eradication therapy plus UHD versus 304/1624 (18.7%) in UHD; low quality evidence) and no treatment (two trials, 207 participants, RR 0.37, 95% CI 0.26 to 0.53; 30/125 (adjusted proportion: 21.7%) in eradication therapy versus 48/82 (58.5%) in no treatment; low quality evidence).In gastric ulcer healing, the differences were imprecise between eradication therapy and UHD (15 trials, 1974 participants, RR 1.23, 95% CI 0.90 to 1.68; 220/1192 (adjusted proportion: 16.0%) in eradication therapy plus UHD versus 102/782 (13.0%) in UHD; very low quality evidence). In preventing duodenal ulcer recurrence the differences were imprecise between maintenance therapy with H.pylori eradication therapy and maintenance therapy with UHD (four trials, 319 participants, RR of ulcer recurring 0.73; 95% CI 0.42 to 1.25; 19/159 (adjusted proportion: 11.9%) in eradication therapy versus 26/160 (16.3%) in UHD; very low quality evidence), but eradication therapy was superior to no treatment (27 trials 2509 participants, RR 0.20, 95% CI 0.15 to 0.26; 215/1501 (adjusted proportion: 12.9%) in eradication therapy versus 649/1008 (64.4%) in no treatment; very low quality evidence).In preventing gastric ulcer recurrence, eradication therapy was superior to no treatment (12 trials, 1476 participants, RR 0.31, 95% CI 0.22 to 0.45; 116/697 (adjusted proportion: 16.3%) in eradication therapy versus 356/679 (52.4%) in no treatment; very low quality evidence). None of the trials reported proportion of people with gastric ulcer not healed after initial therapy between H.pylori eradication therapy and no active treatment or the proportion of people with recurrent gastric ulcer or peptic ulcers during maintenance therapy between H.pylori eradication therapy and ulcer healing drug therapy. AUTHORS' CONCLUSIONS: Adding a one to two-week course of H. pylori eradication therapy is an effective treatment for people with H. pylori-positive duodenal ulcer when compared to ulcer healing drugs alone and no treatment. H. pylori eradication therapy is also effective in preventing recurrence of duodenal and gastric ulcer compared to no treatment. There is currently no evidence that H. pylori eradication therapy is an effective treatment in people with gastric ulcer or that it is effective in preventing recurrence of duodenal ulcer compared to ulcer healing drug. However, confidence intervals were wide and significant benefits or harms of H. pylori eradication therapy in acute ulcer healing of gastric ulcers compared to no treatment, and in preventing recurrence of duodenal ulcers compared to ulcer healing drugs cannot be ruled out
Functional determinants for general Sturm-Liouville problems
Simple and analytically tractable expressions for functional determinants are
known to exist for many cases of interest. We extend the range of situations
for which these hold to cover systems of self-adjoint operators of the
Sturm-Liouville type with arbitrary linear boundary conditions. The results
hold whether or not the operators have negative eigenvalues. The physically
important case of functional determinants of operators with a zero mode, but
where that mode has been extracted, is studied in detail for the same range of
situations as when no zero mode exists. The method of proof uses the properties
of generalised zeta-functions. The general form of the final results are the
same for the entire range of problems considered.Comment: 28 pages, LaTe
Chandra X-ray Observations of the Hydra A Cluster: An Interaction Between the Radio Source and the X-Ray-Emitting Gas
We present Chandra X-ray Observations of the Hydra A cluster of galaxies, and
we report the discovery of structure in the central 80 kpc of the cluster's
X-ray-emitting gas. The most remarkable structures are depressions in the X-ray
surface brightness, kpc diameter, that are coincident with Hydra
A's radio lobes. The depressions are nearly devoid of X-ray-emitting gas, and
there is no evidence for shock-heated gas surrounding the radio lobes. We
suggest the gas within the surface brightness depressions was displaced as the
radio lobes expanded subsonically, leaving cavities in the hot atmosphere. The
gas temperature declines from 4 keV at 70 kpc to 3 keV in the inner 20 kpc of
the brightest cluster galaxy (BCG), and the cooling time of the gas is Myr in the inner 10 kpc. These properties are consistent with the presence
of a \sim 34 \msunyr cooling flow within a 70 kpc radius. Bright X-ray
emission is present in the BCG surrounding a recently-accreted disk of nebular
emission and young stars. The star formation rate is commensurate with the
cooling rate of the hot gas within the volume of the disk, although the sink
for the material cooling at larger radii remains elusive.Comment: 4 pages, 3 figures; submitted to ApJ Letter
Pilot Comparative Effectiveness Study of Surface Perturbation Treadmill Training to Prevent Falls in Older Adults
Falls are the leading cause of fatal and non-fatal injuries among older adults. Exercise programs appear to reduce fall risk, but the optimal type, frequency, and duration of exercise is unknown. External perturbations such as tripping and slipping are a major contributor to falls, and task-specific perturbation training to enhance dynamic stability has emerged as a promising approach to modifying fall risk. The purpose of this pilot study was 1) to determine the feasibility of conducting a large pragmatic randomized trial comparing a multidimensional exercise program inclusive of the surface perturbation treadmill training (SPTT) to multidimensional exercise alone (Standard PT); and 2) to assess fall outcomes between the two groups to determine whether an effect size large enough to warrant further study might be present
Zeta function determinant of the Laplace operator on the -dimensional ball
We present a direct approach for the calculation of functional determinants
of the Laplace operator on balls. Dirichlet and Robin boundary conditions are
considered. Using this approach, formulas for any value of the dimension, ,
of the ball, can be obtained quite easily. Explicit results are presented here
for dimensions and .Comment: 22 pages, one figure appended as uuencoded postscript fil
X-ray Detection of the Primary Lens Galaxy Cluster of the Gravitational Lens System Q0957+561
Analysis of several recent ROSAT HRI observations of the gravitationally
lensed system Q0957+561 has led to the detection at the 3sigma level of the
cluster lens containing the primary galaxy G1. The total mass was estimated by
applying the equation of hydrostatic equilibrium to the detected hot
intracluster gas for a range of cluster core radii, cluster sizes and for
different values of the Hubble constant. X-ray estimates of the lensing cluster
mass provide a means to determine the cluster contribution to the deflection of
rays originating from the quasar Q0957+561. The present mass estimates were
used to evaluate the convergence parameter kappa, the ratio of the local
surface mass density of the cluster to the critical surface mass density for
lensing. The convergence parameter, kappa, calculated in the vicinity of the
lensed images, was found to range between 0.07 and 0.21, depending on the
assumed cluster core radius and cluster extent. This range of uncertainty in
kappa does not include possible systematic errors arising from the estimation
of the cluster temperature through the use of the cluster
luminosity-temperature relation and the assumption of spherical symmetry of the
cluster gas. Applying this range of values of kappa to the lensing model of
Grogin & Narayan (1996) for Q0957+561 but not accounting for uncertainties in
that model yields a range of values for the Hubble constant:67<H_0<82 km s^-1
Mpc^-1, for a time delay of 1.1 years.Comment: Accepted for publication in ApJ, 25 pages, 9 figure
The Evolution of the Intracluster Medium Metallicity in Sunyaev-Zel'dovich-Selected Galaxy Clusters at 0 < z < 1.5
We present the results of an X-ray spectral analysis of 153 galaxy clusters
observed with the Chandra, XMM-Newton, and Suzaku space telescopes. These
clusters, which span 0 < z < 1.5, were drawn from a larger, mass-selected
sample of galaxy clusters discovered in the 2500 square degree South Pole
Telescope Sunyaev Zel'dovich (SPT-SZ) survey. With a total combined exposure
time of 9.1 Ms, these data yield the strongest constraints to date on the
evolution of the metal content of the intracluster medium (ICM). We find no
evidence for strong evolution in the global (r<R500) ICM metallicity (dZ/dz =
-0.06 +/- 0.04 Zsun), with a mean value at z=0.6 of = 0.23 +/- 0.01 Zsun
and a scatter of 0.08 +/- 0.01 Zsun. These results imply that >60% of the
metals in the ICM were already in place at z=1 (at 95% confidence), consistent
with the picture of an early (z>1) enrichment. We find, in agreement with
previous works, a significantly higher mean value for the metallicity in the
centers of cool core clusters versus non-cool core clusters. We find weak
evidence for evolution in the central metallicity of cool core clusters (dZ/dz
= -0.21 +/- 0.11 Zsun), which is sufficient to account for this enhanced
central metallicity over the past ~10 Gyr. We find no evidence for metallicity
evolution outside of the core (dZ/dz = -0.03 +/- 0.06 Zsun), and no significant
difference in the core-excised metallicity between cool core and non-cool core
clusters. This suggests that strong radio-mode AGN feedback does not
significantly alter the distribution of metals at r>0.15R500. Given the
limitations of current-generation X-ray telescopes in constraining the ICM
metallicity at z>1, significant improvements on this work will likely require
next-generation X-ray missions.Comment: 11 pages, 8 figures, 2 tables. Submitted to ApJ. Comments welcome
Analytic frameworks for assessing dialogic argumentation in online learning environments
Over the last decade, researchers have developed sophisticated online learning environments to support students engaging in argumentation. This review first considers the range of functionalities incorporated within these online environments. The review then presents five categories of analytic frameworks focusing on (1) formal argumentation structure, (2) normative quality, (3) nature and function of contributions within the dialog, (4) epistemic nature of reasoning, and (5) patterns and trajectories of participant interaction. Example analytic frameworks from each category are presented in detail rich enough to illustrate their nature and structure. This rich detail is intended to facilitate researchers’ identification of possible frameworks to draw upon in developing or adopting analytic methods for their own work. Each framework is applied to a shared segment of student dialog to facilitate this illustration and comparison process. Synthetic discussions of each category consider the frameworks in light of the underlying theoretical perspectives on argumentation, pedagogical goals, and online environmental structures. Ultimately the review underscores the diversity of perspectives represented in this research, the importance of clearly specifying theoretical and environmental commitments throughout the process of developing or adopting an analytic framework, and the role of analytic frameworks in the future development of online learning environments for argumentation
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