2,661 research outputs found

    The Relationship between Cost Analysis and Program Management

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    Cost analysis if often viewed as applying basic principles and cost methodologies to determine total system cost. These finished estimates then flow into a decision making process and the cost estimator leaves the stage. Reality shows that the cost estimator is actually one of the main contributors to the decision making process. Our introduction to this special issue explores the areas where cost estimating plays a major role in program management in areas beyond the normal program estimate. We have included articles that show the key role estimators can play in source selection strategies and evaluation; cost of delay analysis for management decisions, earned value management methods to predict program costs; decision criteria to rank competing projects that complement traditional cost-based methods; and a new methodology for determining research and development budget profiles

    Cognitive impairment and preferences for current health

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    <p>Abstract</p> <p>Background</p> <p>We assessed preferences for current health using the visual analogue scale (VAS), standard gamble (SG), time trade-off (TTO), and willingness to pay (WTP) in patients with cerebral aneurysms, a population vulnerable to cognitive deficits related to aneurysm bleeding or treatment.</p> <p>Methods</p> <p>We measured VAS, SG, TTO, and WTP values for current health in 165 outpatients with cerebral aneurysms. We assessed cognitive impairment with the Mini Mental State Examination (MMSE; scores < 24 = cognitive impairment). We examined the distributions of preference responses stratified by cognitive status, and the relationship between preferences and cognitive impairment, patient characteristics, and aneurysm history.</p> <p>Results</p> <p>Eleven patients (7%) had MMSE scores < 24. The distribution of preferences responses from patients with cognitive impairment had greater variance (SG, 0.39 vs. 0.21, P = 0.001; TTO, 0.36 vs. 0.24, P = 0.017) and altered morphology (VAS, P = 0.012; SG, P = 0.023) compared to the responses of unimpaired patients. There was good correlation between most preference measures for unimpaired patients (VAS:TTO, rho = 0.19, P = 0.018; SG:TTO, rho = 0.36, P < 0.001; SG:WTP, rho = -0.33, P < 0.001) and a trend towards significance with another pairing (VAS:WTP, rho = 0.16, P = 0.054). In subjects with cognitive impairment, there was a significant correlation only between VAS and TTO scores (rho = 0.76, P = 0.023). Separate regression models showed that cognitive impairment was associated with lower preferences on the VAS (β = -0.12, P = 0.048), SG (β = -0.23, P = 0.002), and TTO (β = -0.17, P = 0.035).</p> <p>Conclusion</p> <p>Cognitive impairment is associated with lower preferences for current health in patients with cerebral aneurysms. Cognitively impaired patients have poor inter-preference test correlations and different response distributions compared to unimpaired patients.</p

    Valence band offset of InN/AlN heterojunctions measured by X-ray photoelectron spectroscopy

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    The valence band offset of wurtzite-InN/AlN (0001) heterojunctions is determined by x-ray photoelectron spectroscopy to be 1.52±0.17 eV. Together with the resulting conduction band offset of 4.0±0.2 eV, a type-I heterojunction forms between InN and AlN in the straddling arrangement

    Surface electronic properties of undoped InAlN alloys

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    The variation in surface electronic properties of undoped c-plane InxAl1−xN alloys has been investigated across the composition range using a combination of high-resolution x-ray photoemission spectroscopy and single-field Hall effect measurements. For the In-rich alloys, electron accumulation layers, accompanied by a downward band bending, are present at the surface, with a decrease to approximately flatband conditions with increasing Al composition. However, for the Al-rich alloys, the undoped samples were found to be insulating with approximate midgap pinning of the surface Fermi level observed

    The Dwarf Novae of Shortest Period

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    We present observations of the dwarf novae GW Lib, V844 Her, and DI UMa. Radial velocities of H-alph yield orbital periods of 0.05332 +- 0.00002 d (= 76.78 m) for GW Lib and and 0.054643 +- 0.000007 d (= 78.69 m) for V844 Her. Recently, the orbital period of DI UMa was found to be only 0.054564 +- 0.000002 d (= 78.57 m) by Fried et al. (1999), so these are the three shortest orbital periods among dwarf novae with normal-abundance secondaries. GW Lib has attracted attention as a cataclysmic binary showing apparent ZZ Ceti-type pulsations of the white dwarf primary. Its spectrum shows sharp Balmer emission flanked by strong, broad Balmer absorption, indicating a dominant contribution by white-dwarf light. Analysis of the Balmer absorption profiles is complicated by the unknown residual accretion luminosity and lack of coverage of the high Balmer lines. Our best-fit model atmospheres are marginally hotter than the ZZ Ceti instability strip, in rough agreement with recent ultraviolet results from HST. The spectrum and outburst behavior of GW Lib make it a near twin of WZ Sge, and we estimate it to have a quiescent V absolute magnitude 12. Comparison with archival data reveals proper motion of 65 +- 12 mas/yr. The mean spectrum of V844 Her is typical of SU UMa dwarf novae. We detected superhumps in the 1997 May superoutburst with superhump period = 0.05597 +- 0.00005 d. The spectrum of DI UMa appears normal for a dwarf nova near minimum light. These three dwarf novae have nearly identical short periods but completely dissimilar outburst characteristics. We discuss possible implications.Comment: Accepted for publication in Publications of the Astronomical Society of the Pacific; 16 pages, 6 figure

    Clinical significance of perioperative Q-wave myocardial infarction: The Emory Angioplasty versus Surgery Trial

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    AbstractObjective: The primary end point of the Emory Angioplasty versus Surgery Trial was a composite of three events: death, Q-wave infarction, and a new large defect on 3-year postoperative thallium scan. This study examines the clinical significance of Q-wave infarction in the surgical cohort (194 patients) of the Emory trial. Methods: Twenty patients (10.3%) with Q-wave infarctions were identified: 13 patients had inferior Q-wave infarctions and seven patients had anterior, lateral, septal, or posterior Q-wave infarctions (termed anterior Q-wave infarctions). Results: In the inferior Q-wave infarction group, postoperative cardiac catheterization (at 1 year or 3 years) in 11 patients revealed normal ejection fraction (ejection fraction >55%) in 10 (91%), no wall motion abnormalities in 10 (91%), and all grafts patent in 10 (91%). In the anterior Q-wave infarction group, postoperative catheterizatiOn in six patients revealed normal ejection fractions in five (83%), no wall motion abnormalities in three (50%), and all grafts patent in three (50%). Average peak postoperative creatine kinase MB levels were as follows: no Q-wave infarction (n = 174) 37 ± 43 IU/L, inferior Q-wave infarction 40 ± 27 IU/L, and anterior Q-wave infarction 58 ± 38 IU/L. Mortality in the 20 patients with Q-wave infarctions was 5% (1/20) at 3 years; in patients without a Q-wave infarction it was 6.3% (11/174) (p = 0.64). Of 17 patients with a Q-wave infarction who underwent postoperative catheterization, 11 (65%) had a normal ejection fraction, normal wall motion, and all grafts patent with an uneventful 3-year postoperative course. Conclusions: The core laboratory screening of postoperative electrocardiograms, particularly in the case of inferior Q-wave infarctions, appears to identify a number of patients as having a Q-wave infarction with minimal clinical significance. Q-wave infarction identified in the postoperative period seems to be a weak end point with little prognostic significance and therefore not valuable for future randomized trials. (J Thorac Cardiovasc Surg 1996;112:1447-54

    Hypertension-induced renal fibrosis and spironolactone response vary by rat strain and mineralocorticoid receptor gene expression

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    Introduction. Aldosterone promotes renal fibrosis via the mineralocorticoid receptor (MR), thus contributing to hypertension-induced nephropathy. We investigated whether MR gene expression influences renal fibrosis and MR antagonist response in a two-kidney, one-clip hypertensive rat model. Materials and methods. Brown Norway (BN), Lewis, and ACI rats were randomised to spironolactone 20 mg/kg/day or water by gavage, starting four weeks after left renal artery clipping. Blood pressure was measured bi-weekly by tail cuff. After eight weeks of treatment, right kidneys were removed and examined for fibrosis and gene expression. Rats of each strain undergoing no intervention served as controls. Results. Blood pressure increased similarly among strains after clipping and was unaffected by spironolactone. Hypertension caused the greatest renal fibrosis in BN rats (p \u3c 0.001 by ANOVA compared to other strains). Real-time PCR analysis showed greater renal collagen type I and MR gene expression in untreated, hypertensive BN rats (both p \u3c 0.05 compared to other strains). Spironolactone attenuated fibrosis, with similar fibrosis among strains of spironolactone-treated rats. Conclusion. Hypertension-induced renal fibrosis was greatest in rats with the highest MR gene expression. Spironolactone abolished inter-strain differences in fibrosis. Our data suggest that MR genotype may influence aldosterone-induced renal damage, and consequently, renal response to aldosterone antagonism

    Do Rotations Beyond the Cosmological Horizon Affect the Local Inertial Frame?

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    If perturbations beyond the horizon have the velocities prescribed everywhere then the dragging of inertial frames near the origin is suppressed by an exponential factor. However if perturbations are prescribed in terms of their angular momenta there is no such suppression. We resolve this paradox and in doing so give new explicit results on the dragging of inertial frames in closed, flat and open universe with and without a cosmological constant.Comment: 12 page

    Development and validation of a 30-day mortality index based on pre-existing medical administrative data from 13,323 COVID-19 patients: The Veterans Health Administration COVID-19 (VACO) Index.

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    BACKGROUND: Available COVID-19 mortality indices are limited to acute inpatient data. Using nationwide medical administrative data available prior to SARS-CoV-2 infection from the US Veterans Health Administration (VA), we developed the VA COVID-19 (VACO) 30-day mortality index and validated the index in two independent, prospective samples. METHODS AND FINDINGS: We reviewed SARS-CoV-2 testing results within the VA between February 8 and August 18, 2020. The sample was split into a development cohort (test positive between March 2 and April 15, 2020), an early validation cohort (test positive between April 16 and May 18, 2020), and a late validation cohort (test positive between May 19 and July 19, 2020). Our logistic regression model in the development cohort considered demographics (age, sex, race/ethnicity), and pre-existing medical conditions and the Charlson Comorbidity Index (CCI) derived from ICD-10 diagnosis codes. Weights were fixed to create the VACO Index that was then validated by comparing area under receiver operating characteristic curves (AUC) in the early and late validation cohorts and among important validation cohort subgroups defined by sex, race/ethnicity, and geographic region. We also evaluated calibration curves and the range of predictions generated within age categories. 13,323 individuals tested positive for SARS-CoV-2 (median age: 63 years; 91% male; 42% non-Hispanic Black). We observed 480/3,681 (13%) deaths in development, 253/2,151 (12%) deaths in the early validation cohort, and 403/7,491 (5%) deaths in the late validation cohort. Age, multimorbidity described with CCI, and a history of myocardial infarction or peripheral vascular disease were independently associated with mortality-no other individual comorbid diagnosis provided additional information. The VACO Index discriminated mortality in development (AUC = 0.79, 95% CI: 0.77-0.81), and in early (AUC = 0.81 95% CI: 0.78-0.83) and late (AUC = 0.84, 95% CI: 0.78-0.86) validation. The VACO Index allows personalized estimates of 30-day mortality after COVID-19 infection. For example, among those aged 60-64 years, overall mortality was estimated at 9% (95% CI: 6-11%). The Index further discriminated risk in this age stratum from 4% (95% CI: 3-7%) to 21% (95% CI: 12-31%), depending on sex and comorbid disease. CONCLUSION: Prior to infection, demographics and comorbid conditions can discriminate COVID-19 mortality risk overall and within age strata. The VACO Index reproducibly identified individuals at substantial risk of COVID-19 mortality who might consider continuing social distancing, despite relaxed state and local guidelines
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