2,390 research outputs found
Reactions to uncertainty and the accuracy of diagnostic mammography.
BackgroundReactions to uncertainty in clinical medicine can affect decision making.ObjectiveTo assess the extent to which radiologists' reactions to uncertainty influence diagnostic mammography interpretation.DesignCross-sectional responses to a mailed survey assessed reactions to uncertainty using a well-validated instrument. Responses were linked to radiologists' diagnostic mammography interpretive performance obtained from three regional mammography registries.ParticipantsOne hundred thirty-two radiologists from New Hampshire, Colorado, and Washington.MeasurementMean scores and either standard errors or confidence intervals were used to assess physicians' reactions to uncertainty. Multivariable logistic regression models were fit via generalized estimating equations to assess the impact of uncertainty on diagnostic mammography interpretive performance while adjusting for potential confounders.ResultsWhen examining radiologists' interpretation of additional diagnostic mammograms (those after screening mammograms that detected abnormalities), a 5-point increase in the reactions to uncertainty score was associated with a 17% higher odds of having a positive mammogram given cancer was diagnosed during follow-up (sensitivity), a 6% lower odds of a negative mammogram given no cancer (specificity), a 4% lower odds (not significant) of a cancer diagnosis given a positive mammogram (positive predictive value [PPV]), and a 5% higher odds of having a positive mammogram (abnormal interpretation).ConclusionMammograms interpreted by radiologists who have more discomfort with uncertainty have higher likelihood of being recalled
Lift Recovery for AFC-Enabled High Lift System
This project is a continuation of the NASA AFC-Enabled Simplified High-Lift System Integration Study contract (NNL10AA05B) performed by Boeing under the Fixed Wing Project. This task is motivated by the simplified high-lift system, which is advantageous due to the simpler mechanical system, reduced actuation power and lower maintenance costs. Additionally, the removal of the flap track fairings associated with conventional high-lift systems renders a more efficient aerodynamic configuration. Potentially, these benefits translate to a approx. 2.25% net reduction in fuel burn for a twin-engine, long-range airplane
Systematic Approach To Case Recertification
LecturePg. 133-138Turbomachinery life expectancy, economic conditions, and plant capacity enhancements have created a need for vintage compressors to be reevaluated and re-engineered for operational parameters that may not have been incorporated in the original design. Aerodynamic revamps have been standard practice for optimizing flow conditions to today's processes. These changeouts have traditionally been limited to manipulation within designed pressure ratings. Recently, in addition to the aerodynamic enhancements, processes are requiring increased pressure levels. These new requirements and requests have posed questions and concerns which have not been of predominant importance previously. Integrity of the containment vessel, leakage of process gases, condition, and life expectancy at above design conditions must be addressed to make an informed comparison between a rerate and purchase of replacement equipment. The hazards and possible expenses of operating turbomachinery above rated pressures without a systematic and consistent verification process should be avoided. Hence, a new field has been undertaken by OEMs driven by equipment user request, to certify existing casings at increased levels in the safest and most reliable manner. The following guidelines have been produced to conduct such rerates with minimal risk to the compressor case and thus, the processes in which these machines play an intricate part: • Specific case testing history • Examine records and designs to determine if the casing has been hydrotested previously, or has been hydrotested to appropriate new condition levels. • Review of similar vintage machinery • Review designs of similar machines built in the same era to determine if ratings have ever been within appropriate levels. • Analyze the specific case design • Analyze the case with the use of modem and proven finite element methods to verify the integrity of the case design at elevated pressures based on blueprint dimensions. Review data with the user, discussing concerns of both parties and come to a consensus whether a hydrotest is feasible. • Inspect and review • Inspect the case per manufacturing blueprints to verify thickness and overall condition of the case and continuity of FEA model. With the use of magnetic particles, inspect the casing for indications and discontinuities which could endanger the casing during the hydrotest. Review the data and determine if continuation of testing is feasible. • Strain gauge casing • Place strain gauge equipment at key high stress locations based on FEA model to protest casing during hydrotesting. • Hydrotest case • With online strain readings, hydrotest casing to the appropriate levels. Carefully monitor the strain data to protect the casing from going beyond prescribed stress levels at the desired pressure levels. If stress levels appear to be approaching recommended limits, consensus should be made on whether to continue. • Recertification • After a successful hydrotest, rerate the compressor name plate and records for the new pressure level. The following paper will use a case history as a step by step example to show how case recertification has been accomplished in the safest possible manner with minimal risk to equipment
Adaptation and enslavement in endosymbiont-host associations
The evolutionary persistence of symbiotic associations is a puzzle.
Adaptation should eliminate cooperative traits if it is possible to enjoy the
advantages of cooperation without reciprocating - a facet of cooperation known
in game theory as the Prisoner's Dilemma. Despite this barrier, symbioses are
widespread, and may have been necessary for the evolution of complex life. The
discovery of strategies such as tit-for-tat has been presented as a general
solution to the problem of cooperation. However, this only holds for
within-species cooperation, where a single strategy will come to dominate the
population. In a symbiotic association each species may have a different
strategy, and the theoretical analysis of the single species problem is no
guide to the outcome. We present basic analysis of two-species cooperation and
show that a species with a fast adaptation rate is enslaved by a slowly
evolving one. Paradoxically, the rapidly evolving species becomes highly
cooperative, whereas the slowly evolving one gives little in return. This helps
understand the occurrence of endosymbioses where the host benefits, but the
symbionts appear to gain little from the association.Comment: v2: Correction made to equations 5 & 6 v3: Revised version accepted
in Phys. Rev. E; New figure adde
Press Release - Senator Edmund S. Muskie Disputes a Story of Deadlock on Drug Abuse Legislation
Senators Javits, Percy, Gurney, Ribicoff, Hughes, and Muskie issued a statement disputing a New York Times news report which asserted that a deadlock existed between the Congress and the White House over pending drug abuse control legislation
A clinical evaluation committee assessment of recombinant human tissue factor pathway inhibitor (tifacogin) in patients with severe community-acquired pneumonia
INTRODUCTION: The purpose of this analysis was to determine the potential efficacy of recombinant human tissue factor pathway inhibitor (tifacogin) in a subpopulation of patients with community-acquired pneumonia (CAP) from a phase III study of severe sepsis. METHODS : A retrospective review of patients with suspected pneumonia was conducted by an independent clinical evaluation committee (CEC) blinded to treatment assignment. The CEC reanalyzed data from patients enrolled in an international multicenter clinical trial of sepsis who had a diagnosis of pneumonia as the probable source of sepsis. The primary efficacy measure was all-cause 28-day mortality. RESULTS: Of 847 patients identified on case report forms with a clinical diagnosis of pneumonia, 780 (92%) were confirmed by the CEC to have pneumonia. Of confirmed pneumonia cases, 496 (63.6%) met the definition for CAP. In the CEC CAP population, the mortality rates of the tifacogin and placebo groups were 70/251 (27.9%) and 80/245 (32.7%), respectively. The strongest signals were seen in patients with CAP not receiving concomitant heparin, having microbiologically confirmed infection, or having the combination of documented infection and no heparin. The reduction in mortality in this narrowly defined subgroup when treated with tifacogin compared with placebo was statistically significant (17/58 [29.3%] with tifacogin and 28/54 [51.9%] with placebo; unadjusted P value of less than 0.02). CONCLUSIONS: Tifacogin administration did not significantly reduce mortality in any severe CAP patient. Exploratory analyses showed an improved survival in patients who did not receive concomitant heparin with microbiologically confirmed infections. These data support the rationale of an ongoing phase III study exploring the potential benefit of tifacogin in severe CAP. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT00084071
Loss of Bladder Epithelium Induced by Cytolytic Mast Cell Granules
Programmed death and shedding of epithelial cells is a powerful defense mechanism to reduce bacterial burden during infection but this activity cannot be indiscriminate because of the critical barrier function of the epithelium. We report that during cystitis, shedding of infected bladder epithelial cells (BECs) was preceded by the recruitment of mast cells (MCs) directly underneath the superficial epithelium where they docked and extruded their granules. MCs were responding to interleukin-1β (IL-1β) secreted by BECs after inflammasome and caspase-1 signaling. Upon uptake of granule-associated chymase (mouse MC protease 4 [mMCPT4]), BECs underwent caspase-1-associated cytolysis and exfoliation. Thus, infected epithelial cells require a specific cue for cytolysis from recruited sentinel inflammatory cells before shedding
py4DSTEM: a software package for multimodal analysis of four-dimensional scanning transmission electron microscopy datasets
Scanning transmission electron microscopy (STEM) allows for imaging,
diffraction, and spectroscopy of materials on length scales ranging from
microns to atoms. By using a high-speed, direct electron detector, it is now
possible to record a full 2D image of the diffracted electron beam at each
probe position, typically a 2D grid of probe positions. These 4D-STEM datasets
are rich in information, including signatures of the local structure,
orientation, deformation, electromagnetic fields and other sample-dependent
properties. However, extracting this information requires complex analysis
pipelines, from data wrangling to calibration to analysis to visualization, all
while maintaining robustness against imaging distortions and artifacts. In this
paper, we present py4DSTEM, an analysis toolkit for measuring material
properties from 4D-STEM datasets, written in the Python language and released
with an open source license. We describe the algorithmic steps for dataset
calibration and various 4D-STEM property measurements in detail, and present
results from several experimental datasets. We have also implemented a simple
and universal file format appropriate for electron microscopy data in py4DSTEM,
which uses the open source HDF5 standard. We hope this tool will benefit the
research community, helps to move the developing standards for data and
computational methods in electron microscopy, and invite the community to
contribute to this ongoing, fully open-source project
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