Gamma-Ray Bursts: The Underlying Model

A pedagogical derivation is presented of the ``fireball'' model of gamma-ray bursts, according to which the observable effects are due to the dissipation of the kinetic energy of a relativistically expanding wind, a ``fireball.'' The main open questions are emphasized, and key afterglow observations, that provide support for this model, are briefly discussed. The relativistic outflow is, most likely, driven by the accretion of a fraction of a solar mass onto a newly born (few) solar mass black hole. The observed radiation is produced once the plasma has expanded to a scale much larger than that of the underlying ``engine,'' and is therefore largely independent of the details of the progenitor, whose gravitational collapse leads to fireball formation. Several progenitor scenarios, and the prospects for discrimination among them using future observations, are discussed. The production in gamma- ray burst fireballs of high energy protons and neutrinos, and the implications of burst neutrino detection by kilometer-scale telescopes under construction, are briefly discussed.Comment: In "Supernovae and Gamma Ray Bursters", ed. K. W. Weiler, Lecture Notes in Physics, Springer-Verlag (in press); 26 pages, 2 figure

No short-cut in assessing trial quality: a case study

Assessing the quality of included trials is a central part of a systematic review. Many check-list type of instruments for doing this exist. Using a trial of antibiotic treatment for acute otitis media, Burke et al., BMJ, 1991, as the case study, this paper illustrates some limitations of the check-list approach to trial quality assessment. The general verdict from the check list type evaluations in nine relevant systematic reviews was that Burke et al. (1991) is a good quality trial. All relevant meta-analyses extensively used its data to formulate therapeutic evidence. My comprehensive evaluation, on the other hand, brought to the surface a series of serious problems in the design, conduct, analysis and report of this trial that were missed by the earlier evaluations. A check-list or instrument based approach, if used as a short-cut, may at times rate deeply flawed trials as good quality trials. Check lists are crucial but they need to be augmented with an in-depth review, and where possible, a scrutiny of the protocol, trial records, and original data. The extent and severity of the problems I uncovered for this particular trial warrant an independent audit before it is included in a systematic review

Diffuse intrinsic pontine glioma: current insights and future directions

Abstract Diffuse intrinsic pontine glioma (DIPG) is a lethal pediatric brain tumor and the leading cause of brain tumor–related death in children. As several clinical trials over the past few decades have led to no significant improvements in outcome, the current standard of care remains fractionated focal radiation. Due to the recent increase in stereotactic biopsies, tumor tissue availabilities have enabled our advancement of the genomic and molecular characterization of this lethal cancer. Several groups have identified key histone gene mutations, genetic drivers, and methylation changes in DIPG, providing us with new insights into DIPG tumorigenesis. Subsequently, there has been increased development of in vitro and in vivo models of DIPG which have the capacity to unveil novel therapies and strategies for drug delivery. This review outlines the clinical characteristics, genetic landscape, models, and current treatments and hopes to shed light on novel therapeutic avenues and challenges that remain

Differences in Patient-Reported Processes and Outcomes Between Men and Women with Myocardial Infarction

OBJECTIVE: Previous research measuring differences in the care between men and women with myocardial infarction has focused on differences in procedure use and mortality. However, little is known about differences in processes and outcomes that are reported by patients, such as interpersonal processes of care and health status. Our goal was to measure differences in patient-reported measures for men and women who recently were hospitalized with myocardial infarction. PARTICIPANTS AND SETTING: We surveyed by mail patients with myocardial infarction discharged to home from one of 27 Cleveland area hospitals 3 months following discharge; 502 (64%) of 783 patients responded. The mean age of subjects was 65 years and 40% were women. MEASUREMENTS: Process measures included the quality of communication during the hospitalization and at time of discharge and reports of health education discussions during hospitalization. Outcome measures included physical and mental health component scores of the Medical Outcomes Study 36-Item Short-Form Health Survey, change in work status, and days spent in bed because of ill health. We compared processes and outcomes in men and women using multivariate analyses that adjusted for age, other demographic characteristics, comorbid conditions, severity of the myocardial infarction, and premorbid global health status. MAIN RESULTS: In multivariate analyses, women were as likely as men to report at least one problem with communication during the hospitalization (odds ratio [OR] 0.86; 95% confidence interval [95% CI] 0.56 to 1.33) or at time of discharge (OR 1.24; 95% CI, 0.82 to 1.89) and to report that they were given dietary advice before discharge (OR 0.60; 95% CI, 0.36 to 1.01), were told what to do if they developed chest pain (OR 1.21; 95% CI, 0.66 to 2.23), or, if they smoked cigarettes, given advice about how to stop smoking (OR 0.64; 95% CI, 0.26 to 1.58). However, 3 months after discharge, women reported worse physical health (P < .05) and mental health (P < .05), were more likely to report spending time in bed because of ill health (OR 1.80; 95% CI, 1.06, 3.05), and were more likely to report working less than before their myocardial infarction (OR 4.02; 95% CI, 1.58 to 10.20). CONCLUSIONS: In terms of processes of care measured with patient reports, women with myocardial infarction reported their quality of care to be similar to that of men. However, 3 months following myocardial infarction, women reported worse health status and were less likely to return to work than men