322 research outputs found
RSM 1.0 user's guide: A resupply scheduler using integer optimization
The Resupply Scheduling Model (RSM) is a PC based, fully menu-driven computer program. It uses integer programming techniques to determine an optimum schedule to replace components on or before a fixed replacement period, subject to user defined constraints such as transportation mass and volume limits or available repair crew time. Principal input for RSJ includes properties such as mass and volume and an assembly sequence. Resource constraints are entered for each period corresponding to the component properties. Though written to analyze the electrical power system on the Space Station Freedom, RSM is quite general and can be used to model the resupply of almost any system subject to user defined resource constraints. Presented here is a step by step procedure for preparing the input, performing the analysis, and interpreting the results. Instructions for installing the program and information on the algorithms are given
Marshall University Music Department Presents The Marshall University Symphony Orchestra, in, Who\u27s Afraid of the Orchestra?, Dr. Elizabeth Reed Smith, conductor, Dr. Larry Stickler, narrator
https://mds.marshall.edu/music_perf/1733/thumbnail.jp
Forecasting economic impacts of the Third Harbor Tunnel
Thesis (M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 1989.Includes bibliographical references (leaves 99-100).by Larry Donnell Reed.M.C.P
Quantifying Women's Stated BenefitāRisk Trade-Off Preferences for IBS Treatment Outcomes
Background: The Food and Drug Administration, currently, is exploring quantitative benefitārisk methods to support regulatory decision-making. A scientifically valid method for assessing patients' benefitārisk trade-off preferences is needed to compare risks and benefits in a common metric. Objectives: The study aims to quantify the maximum acceptable risk (MAR) of treatment-related adverse events (AEs) that women with diarrhea-predominant irritable bowel syndrome (IBS) are willing to accept in exchange for symptom relief. Methods: Research design: A stated-choice survey was used to elicit trade-off preferences among constructed treatment profiles, each defined by symptom severity and treatment-related AEs. Symptom attributes included frequency of abdominal pain and discomfort, frequency of diarrhea, and frequency of urgency. AE attributes included frequency of mild-to-moderate constipation and the risk of four possible serious AEs. Subjects: A Web-enabled survey was administered to 589 female US residents at least 18 years of age with a self-reported diagnosis of diarrhea-predominant IBS. Measures: Preference weights and MAR were estimated using mixed-logit methods. Results: Subjects were willing to accept higher risks of serious AEs in return for treatments offering better symptom control. For an improvement from the lowest to the highest of four benefit levels, subjects were willing to tolerate a 2.65% increase in impacted-bowel risk, but only a 1.34% increase in perforated-bowel risk. Conclusions: Variation in MARs across AE types is consistent with the relative seriousness of the AEs. Stated-preference methods offer a scientifically valid approach to quantifying benefitārisk trade-off preferences that can be used to inform regulatory decision-making
Spatial Learning as an Adaptation in Hummingbirds
An ecological approach based on food distribution suggests that hummingbirds should more easily learn to visit a flower in a new location than to learn to return to a flower in a position just visited, for a food reward. Experimental results support this hypothesis as well as the general view that differences in learning within and among species represent adaptations
Diagnosis and Initial Management of Blunt Pancreatic Trauma: Guidelines From a Multiinstitutional Review
OBJECTIVE: The authors' objective was to resolve the current controversies surrounding the diagnosis and management of blunt pancreatic trauma (BPT). SUMMARY BACKGROUND DATA: The diagnosis of BPT is notoriously difficult: serum amylase has been claimed to be neither sensitive nor specific, and recent anecdotal reports have suggested a role for computed tomography. The therapy of BPT has been controversial, with some suggesting selective observation and others advocating immediate exploration to prevent a delay-induced escalation in morbidity and death. METHODS: The authors conducted a retrospective chart review of documented BPT from six institutions, using a standardized binary data form composed of 187 items and 237 data fields. RESULTS: A significant correlation between pancreas-specific morbidity and injury to the main pancreatic duct (MPD) was noted. Patients requiring delayed surgical intervention after an unsuccessful period of observation demonstrated notably higher pancreas-specific mortality and morbidity rates, principally because of the incidence of unrecognized injuries to the MPD. Although detection of MPD injuries by computed tomography was no better than flipping a coin, endoscopic pancreatography was accurate in each of the five cases in which it was used. CONCLUSIONS: The principal cause of pancreas-specific morbidity after BPT is injury to the MPD. Parenchymal pancreatic injuries not involving the ductal system rarely result in pancreas-specific morbidity or death. Delay in recognizing MPD injury leads to increased mortality and morbidity rates. CT is unreliable in diagnosing MPD injury and should not be used to guide therapy. Initial selection of patients with isolated BPT for observation or surgery can be based on the determination of MPD integrity
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High-speed Photography of Pyrotechnic Materials and Components with a Coppper Vapor Laser
The evaluation of the properties of energetic materials, such as burn rate and ignition energy, is of primary importance in understanding their reactions and the functioning of devices containing them. One method for recording such information is high-speed photography at rates of up to 20,000 images per second. When a copper vapor lazer is synchronized with the camera, laser-illuminated images can be recorded that detail the performance of a material or component in a manner never before possible. Recent results from high-speed photography of several pyrotechnic materials and devices will be presented. These include a pyrotechnic torch, laser ignition of high explosives, and a functioning igniter. Equilibrium chemical computations have recently been begun on the pyrotechnic torch to obtain flame compositions and temperatures. The results of these calculations, and their explanation of the change in torch function with composition, will be discussed
Using the Incremental Net Benefit Framework for Quantitative BenefitāRisk Analysis in Regulatory Decision-MakingāA Case Study of Alosetron in Irritable Bowel Syndrome
AbstractObjectiveThere is consensus that a more transparent, explicit, and rigorous approach to benefitārisk evaluation is required. The objective of this study is to evaluate the incremental net benefit (INB) framework for undertaking quantitative benefitārisk assessment by performing a quantitative benefitārisk analysis of alosetron for the treatment of irritable bowel syndrome from the patientsā perspective.MethodsA discrete event simulation model was developed to determine the INB of alosetron relative to placebo, calculated as ārelative value-adjusted life-years (RVALYs).āResultsIn the base case analysis, alosetron resulted in a mean INB of 34.1 RVALYs per 1000 patients treated relative to placebo over 52 weeks of treatment. Incorporating parameter uncertainty into the model, probabilistic sensitivity analysis revealed a mean INB of 30.4 (95% confidence interval 15.9ā45.4) RVALYs per 1000 patients treated relative to placebo over 52 weeks of treatment. Overall, there was >99% chance that both the incremental benefit and incremental risk associated with alosetron are greater than placebo. As hypothesized, the INB of alosetron was greatest in patients with the worst quality of life experienced at baseline. The mean INB associated with alosetron in patients with mild, moderate, and severe symptoms at baseline was 17.97 (ā0.55 to 36.23), 29.98 (17.05ā43.37), and 35.98 (23.49ā48.77) RVALYs per 1000 patients treated, respectively.ConclusionsThis study demonstrates the potential utility of applying the INB framework to real-life decision-making, and the ability to use simulation modeling incorporating outcomes data from different sources as a benefitārisk decision aid
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