86 research outputs found
Academic chartered data safety committees versus industry sponsored data safety committees: The need for different recommendations
Dear Editor,
We read with great interest the recently published
paper by Calis et al.1 We applaud the authors and the
working group for developing this important set of recommendations
for data monitoring committees
(DMC). Recommendations for organizing a DMC are
long overdue. Our academic institution has had a formal
DMC for many years which administratively
reports to an academic official who directs the research
efforts. It has a formal charter and broad membership
that includes clinicians, clinical trial specialists, and a
biostatistician. It accepts for review studies that require
a DMC (usually phase II or III trials) and are not
sponsored by industry, which usually set up their own
DMC. Most studies are supported by the institution,
US Government research funding sources (e.g.
National Institutes of Health (NIH), Centers for
Disease Control and Prevention), or research
foundations
Classifying medical histories in US medicare beneficiaries using fixed vs allâavailable lookâback approaches
Purpose: Evaluate use of fixed and allâavailable lookâbacks to identify eligibility criteria and confounders among Medicare beneficiaries. Methods: We identified outpatient visits (2007â2012) with recently documented (â€180 days) cardiovascular risk and classified patients according to whether the exposure (statin) was initiated within 14 days. We selected each beneficiary's first eligible visit (in each treatment group) that met criteria during the respective lookâbacks: continuous enrollment (1 or 3 years for fixed lookâback; 180 days for allâavailable), no cancer history, and no statin claims. We estimated crude and standardized mortality ratio weighted hazard ratios (HRs) for the effect of statin initiation on incident 6âmonth cancer (a known null effect) and 2âyear mortality, separately, adjusting for covariates assessed by using each lookâback. Results: Analyzing shortâterm cancer, the estimated HR from the allâavailable approach (HR = 0.90, 95% CI: 0.83, 0.98) was less biased than the 1âyear lookâback (HR = 0.79, 95% CI: 0.73, 0.84), which included beneficiaries with prevalent cancer. The 3âyear lookâback (HR = 1.05, 95% CI: 0.90, 1.21) was somewhat less biased than the allâavailable estimate but less precise due the exclusion of a large proportion of observations without sufficient continuous enrollment (62.0% and 59.9% of initiators and nonâinitiators, respectively). All approaches produced similar estimates of the effect on allâcause mortality. Alternative lookâbacks did not differ in their ability to control confounding. Conclusions: The allâavailable lookâback performed nearly as well as the 3âyear fixed, which produced the least biased point estimate. If 3âyear lookâbacks are infeasible (eg, due to power/sample), allâavailable lookâbacks may be preferable to short (1âyear) fixed lookâbacks
Combination therapy improves survival after acute myocardial infarction in the elderly with chronic kidney disease
Background: Individuals with chronic kidney disease have a high mortality rate after acute myocardial infarction. It is not known how frequently these individuals are prescribed combination cardioprotective therapy and if survival is affected by such therapy after acute myocardial infarction. Methods: A retrospective cohort study of 1,342 Medicare recipients with acute myocardial infarction. Data were collected by medical chart abstraction as part of the Cooperative Cardiovascular Project in 60 hospitals in North Carolina during 5/30/1996-12/28/1997. We categorized cardioprotective medication use as aspirin alone, aspirin with beta-blockers, and aspirin with beta-blockers and ace-inhibitors. Chronic kidney disease was defined as a derived glomerular filtration rate (GFR) ranging from 15-89 mL/min/1.73 m2. Cox proportional hazards regression analyses were performed to determine the effect of cardioprotective medication use on survival while controlling for potential explanatory variables. Results: The prevalence of cardioprotective medication use differed among levels of chronic kidney disease. Those with severe kidney disease (GFR 15-29 mL/min/1.73 m2) were less frequently prescribed aspirin with beta-blockers, 27.1%, and only 8.6% were prescribed aspirin with beta-blockers and ace-inhibitors. Survival was improved with prescribed cardioprotective medication use. In severe kidney disease (GFR 15-29 mL/min/1.73 m2), the hazards risk for death was 0.21 (0.08, 0.53) for aspirin alone, 0.17 (0.06, 0.51) for aspirin with beta-blockers, and 0.35 (0.09, 1.42) for aspirin with beta-blockers and ace-inhibitors. Conclusions: Individuals with chronic kidney disease benefit from combination cardioprotective therapy, but are less likely to be prescribed them after acute myocardial infarction. Further investigation is warranted to identify possible reasons for these observed treatment disparities
Is the Sun Embedded in a Typical Interstellar Cloud?
The physical properties and kinematics of the partially ionized interstellar
material near the Sun are typical of warm diffuse clouds in the solar vicinity.
The interstellar magnetic field at the heliosphere and the kinematics of nearby
clouds are naturally explained in terms of the S1 superbubble shell. The
interstellar radiation field at the Sun appears to be harder than the field
ionizing ambient diffuse gas, which may be a consequence of the low opacity of
the tiny cloud surrounding the heliosphere. The spatial context of the Local
Bubble is consistent with our location in the Orion spur.Comment: "From the Outer Heliosphere to the Local Bubble", held at
International Space Sciences Institute, October 200
Size Doesn't Matter: Towards a More Inclusive Philosophy of Biology
notes: As the primary author, OâMalley drafted the paper, and gathered and analysed data (scientific papers and talks). Conceptual analysis was conducted by both authors.publication-status: Publishedtypes: ArticlePhilosophers of biology, along with everyone else, generally perceive life to fall into two broad categories, the microbes and macrobes, and then pay most of their attention to the latter. âMacrobeâ is the word we propose for larger life forms, and we use it as part of an argument for microbial equality. We suggest that taking more notice of microbes â the dominant life form on the planet, both now and throughout evolutionary history â will transform some of the philosophy of biologyâs standard ideas on ontology, evolution, taxonomy and biodiversity. We set out a number of recent developments in microbiology â including biofilm formation, chemotaxis, quorum sensing and gene transfer â that highlight microbial capacities for cooperation and communication and break down conventional thinking that microbes are solely or primarily single-celled organisms. These insights also bring new perspectives to the levels of selection debate, as well as to discussions of the evolution and nature of multicellularity, and to neo-Darwinian understandings of evolutionary mechanisms. We show how these revisions lead to further complications for microbial classification and the philosophies of systematics and biodiversity. Incorporating microbial insights into the philosophy of biology will challenge many of its assumptions, but also give greater scope and depth to its investigations
History of clinical transplantation
How transplantation came to be a clinical discipline can be pieced together by perusing two volumes of reminiscences collected by Paul I. Terasaki in 1991-1992 from many of the persons who were directly involved. One volume was devoted to the discovery of the major histocompatibility complex (MHC), with particular reference to the human leukocyte antigens (HLAs) that are widely used today for tissue matching.1 The other focused on milestones in the development of clinical transplantation.2 All the contributions described in both volumes can be traced back in one way or other to the demonstration in the mid-1940s by Peter Brian Medawar that the rejection of allografts is an immunological phenomenon.3,4 © 2008 Springer New York
Auroral Processes at the Giant Planets: Energy Deposition, Emission Mechanisms, Morphology and Spectra
A MODEST review
We present an account of the state of the art in the fields explored by the
research community invested in 'Modeling and Observing DEnse STellar systems'.
For this purpose, we take as a basis the activities of the MODEST-17
conference, which was held at Charles University, Prague, in September 2017.
Reviewed topics include recent advances in fundamental stellar dynamics,
numerical methods for the solution of the gravitational N-body problem,
formation and evolution of young and old star clusters and galactic nuclei,
their elusive stellar populations, planetary systems, and exotic compact
objects, with timely attention to black holes of different classes of mass and
their role as sources of gravitational waves.
Such a breadth of topics reflects the growing role played by collisional
stellar dynamics in numerous areas of modern astrophysics. Indeed, in the next
decade, many revolutionary instruments will enable the derivation of positions
and velocities of individual stars in the Milky Way and its satellites and will
detect signals from a range of astrophysical sources in different portions of
the electromagnetic and gravitational spectrum, with an unprecedented
sensitivity. On the one hand, this wealth of data will allow us to address a
number of long-standing open questions in star cluster studies; on the other
hand, many unexpected properties of these systems will come to light,
stimulating further progress of our understanding of their formation and
evolution.Comment: 42 pages; accepted for publication in 'Computational Astrophysics and
Cosmology'. We are much grateful to the organisers of the MODEST-17
conference (Charles University, Prague, September 2017). We acknowledge the
input provided by all MODEST-17 participants, and, more generally, by the
members of the MODEST communit
Electron and photon energy calibration with the ATLAS detector using LHC Run 2 data
This paper presents the electron and photon energy calibration obtained with the ATLAS detector using 140 fb-1 of LHC proton-proton collision data recorded at â(s) = 13 TeV between 2015 and 2018. Methods for the measurement of electron and photon energies are outlined, along with the current knowledge of the passive material in front of the ATLAS electromagnetic calorimeter. The energy calibration steps are discussed in detail, with emphasis on the improvements introduced in this paper. The absolute energy scale is set using a large sample of Z-boson decays into electron-positron pairs, and its residual dependence on the electron energy is used for the first time to further constrain systematic uncertainties. The achieved calibration uncertainties are typically 0.05% for electrons from resonant Z-boson decays, 0.4% at ET ⌠10 GeV, and 0.3% at ET ⌠1 TeV; for photons at ET ⌠60 GeV, they are 0.2% on average. This is more than twice as precise as the previous calibration. The new energy calibration is validated using J/Ï â ee and radiative Z-boson decays
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