4,217 research outputs found

    Improved prediction of laminar leading edge separation

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    Research was conducted to provide a definite criterion for the prediction of the bubble burst on airfoils typical of those used for fighter wings. The approach taken was to correlate existing airfoil bubble burst data using various parameters at the laminar separation point. The method due to Weber was modified to provide a continuous analytic solution for the velocity distribution around the airfoil leading edge. Coupling the modified Weber method with the Stratford laminar separation prediction method leads to a universal chart giving the conditions at separation as a function of stagnation location and leading edge radius. Application of the combined method to available two-dimensional airfoil data resulted in an empirical criterion presenting the limiting local velocity gradient at separation as a function of the boundary layer momentum thickness at separation for bubble burst. The correlation leads as well to the qualitative explanation of two types of laminar stall: thin airfoil and leading edge. The validity of the correlation is demonstrated by predicting the lift coefficient and angle of attack for stall on airfoils with leading edge or trailing edge flaps

    Inconsistent Divergence of Mitochondrial-DNA in the Spontaneously Hypertensive Rat

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    We have recently shown that the spontaneously hypertensive rat (SHR) and the Wistar-Kyoto (WKY) rat differ at a frequency of 1 per 62 bases in their nuclear DNA (Hypertension 1992;19:425-427). Given the origin of these strains this level of divergence was unexpected. To investigate the origin of this nuclear divergence we have examined mitochondrial DNA. Mitochondrial DNA was isolated from SHR and WKY rats, digested with several restriction enzymes, electrophoresed in 1.0% agarose gels, and the fragments visualized with ethidium bromide staining. This approach allowed us to analyze 220 base pairs of mitochondrial DNA. No differences were detected between SHR and WKY rats. Comparison with the King-Holtzman rat strain produced differences at an average of 1 per 52 base pairs. We also examined several SHR and WKY rats from within our colonies and found no differences suggesting intrastrain homogeneity for mitochondrial DNA phenotypes. These data indicate that the SHR and WKY rat share a recent, common maternal ancestor. This result is consistent with the published origins of the SHR and WKY rat strains. Together with the nuclear divergence results, the data suggest that the original Wistar colony from which SHR and WKY rats were derived was probably highly polymorphic for nuclear genes

    Pilot Testing Behavior Therapy for Chronic Tic Disorders in Neurology and Developmental Pediatrics Clinics

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    Comprehensive Behavioral Intervention for Tics (CBIT) is an efficacious treatment with limited regional availability. As neurology and pediatric clinics are often the first point of therapeutic contact for individuals with tics, the present study assessed preliminary treatment response, acceptability, and feasibility of an abbreviated version, modified for child neurology and developmental pediatrics clinics. Fourteen youth (9-17) with Tourette disorder across 2 child neurology clinics and one developmental pediatrics clinic participated in a small case series. Clinician-rated tic severity (Yale Global Tic Severity Scale) decreased from pre- to posttreatment, z = –2.0, P \u3c .05, r = –.48, as did tic-related impairment, z = –2.4, P \u3c .05, r = –.57. Five of the 9 completers (56%) were classified as treatment responders. Satisfaction ratings were high, and therapeutic alliance ratings were moderately high. Results provide guidance for refinement of this modified CBIT protocol

    HEY LARRY! INVESTIGATING INTERRUPTIONS IN FUTURE VERTICAL LIFT PLATFORMS

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    Using technology to improve human performance is critical to maximizing the benefits of future combat systems. This study explores the effects of interruptions during high and low cognitive load states when completing dynamic tasks. Furthermore, it provides insight into how to integrate artificial intelligence and virtual assistants into future aircraft effectively. This research and the following analysis provided the Holistic Situation Awareness and Decision Making (HSA-DM) program office with meaningful data and recommendations that will enable them to reduce the impact of interruptions while improving the performance of future pilots. Specifically, this study collected and examined heart rate variability, subjective cognitive load, flight metrics, interruption lag, and task resumption lag while participants piloted an aircraft and performed dynamic tasks in a flight simulator. There were three different modalities used to assist participants with completing interrupted tasks while performing their primary task. The research team determined that the tactile activated artificial intelligence was the most effective at reducing total interruption time while having the smallest effects on flight performance and cognitive load.Major, United States ArmyMajor, United States ArmyCaptain, United States ArmyCaptain, United States ArmyCaptain, United States ArmyApproved for public release. Distribution is unlimited

    The organophosphate-degrading enzyme from Agrobacterium radiobacter displays mechanistic flexibility for catalysis

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    The OP (organophosphate)-degrading enzyme from Agrobacterium radiobacter (OpdA) is a binuclear metallohydrolase able to degrade highly toxic OP pesticides and nerve agents into less or non-toxic compounds. In the present study, the effect of metal ion substitutions and site-directed mutations on the catalytic properties of OpdA are investigated. The study shows the importance of both the metal ion composition and a hydrogenbond network that connects the metal ion centre with the substrate-binding pocket using residues Arg254 and Tyr257 in the mechanism and substrate specificity of this enzyme. For theCo(II) derivative of OpdA two protonation equilibria (pKa1 ∌5; pKa2 ∌10) have been identified as relevant for catalysis, and a terminal hydroxide acts as the likely hydrolysis-initiating nucleophile. In contrast, the Zn(II) and Cd(II) derivatives only have one relevant protonation equilibrium (pKa ∌4–5), and theÎŒOHis the proposed nucleophile. The observed mechanistic flexibility may reconcile contrasting reaction models that have been published previously and may be beneficial for the rapid adaptation of OP-degrading enzymes to changing environmental pressures

    Endocrine disrupting chemicals removal in an aerobic granular sludge reactor treating simulated saline wastewater

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    The occurrence of Endocrine disrupting chemicals (EDCs) in the environment is a topic of concern. It is commonly accepted that the major source of EDCs to the environment is wastewater treatment plants effluents. Salinity is an additional common stress factor in wastewater treatment. Aerobic granular sludge (AGS) has a number of properties that make it more attractive than conventional biological systems for treatment of wastewater containing EDCs. In the present study, an AGS sequencing batch reactor adapted to salinity was operated for 140 days for treating synthetic saline wastewater containing 17ÎČ–estradiol (E2), 17α–ethinylestradiol (EE2) and bisphenol-A (BPA). E2 was removed by biodegradation. EE2 adsorption/desorption to the aerobic granules was observed. The increasing of BPA removal efficiency after bioaugmentation with a degrading bacterial strain shows that biodegradation was the removal mechanism. COD removal was not significantly affected by EDCs shock loads. Activity of ammonia oxidizing bacteria and nitrite oxidizing bacteria did not seem to be inhibited by the presence of EDCs. The activity of phosphate accumulating organisms was affected.info:eu-repo/semantics/publishedVersio

    The significance of seniority for women managers’ interpretations of organizational restructuring

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    This paper examines the impact of restructuring within the transport and logistics sector on women managers working at senior and less senior (middle/junior management) levels of the organization. The majority of women experienced increased performance pressures and heavier workloads as well as an increase in working hours. At the same time, there were pressures to work at home (i.e. week-ends and evenings) and reduced opportunities to work from home (i.e. during normal office hours). Management level emerged as an important factor in how these changes were interpreted. Senior managers perceived more positive outcomes in terms of increased motivation and loyalty. Despite a longer working week, they were less likely to report low morale as an outcome from long hours. In fact, irrespective of management level, women working shorter hours were more likely to report low morale as an outcome. Results are discussed in relation to literature on restructuring and careers, in terms of perceptual framing and in relation to different levels of investment in the organization

    Rhodococcus sp. ED55: a bacterial strain with ability to degrade endocrine disrupting chemicals and potential for bioaugmentation

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    The occurrence of Endocrine disrupting chemicals (EDCs) in the environment is a topic of concern. It is commonly accepted that the major source of EDCs to the environment is wastewater treatment plants (WWTPs’) effluents, due to the inefficiency of WWTPs to remove this kind of pollutants. A bacterial strain – Rhodococcus sp. ED55 was isolated from the sediments of a discharge point of a WWTP in Coloane, Macau, for its ability to degrade EDCs. The bacterium was able to biodegrade 17ÎČ–estradiol (E2), 17α–ethinylestradiol (EE2), bisphenol-A (BPA) and bisphenol-S (BPS) at different extents. Strain ED55 was able to completely degrade the supplied amount of E2 in few hours, both in synthetic medium and in real wastewater from a municipal WWTP (Parada, Maia – Portugal). Estrone (E1), 4OH-E1 and 4OH-E2 were identified as intermediate degradation metabolites and the metabolic pathway is under elucidation. Bioaugmentation with Rhodococcus sp. ED 55 significantly improved the natural attenuation of the compound in municipal wastewater in batch assays. The acute test with luminescent marine bacterium Vibrio fischeri revealed elimination of the toxicity of the treated effluent and the standardized yeast estrogenic (S-YES) assay with the recombinant strain of Saccharomyces cerevisiae revealed decrease of estrogenic activity of samples. Rhodococcus sp. ED55 was applied in a strategy of an AGS sequencing batch reactor adapted to salinity, which was operated for treating a synthetic saline wastewater containing E2, EE2 and BPA. E2 was no longer detected in the bulk liquid after 10 min of aerobic reaction throughout reactor operation, suggesting that this compound was quickly removed by biodegradation. EE2 adsorption/desorption to the aerobic granules was observed. Removal of BPA significantly increased after bioaugmentation with Rhodococcus sp. ED55, showing that biodegradation was the governing removal mechanism. COD removal was not significantly affected by EDCs shock loads. Rhodococcus sp. ED55 can potentially be applied in bioaugmentation strategies for ameliorating treatment of wastewater contaminated with EDCs.info:eu-repo/semantics/publishedVersio

    Effectiveness of implementing a wake up and breathe program on sedation and delirium in the ICU

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    OBJECTIVES: Mechanically ventilated critically ill patients receive significant amounts of sedatives and analgesics that increase their risk of developing coma and delirium. We evaluated the impact of a "Wake-up and Breathe Protocol" at our local ICU on sedation and delirium. DESIGN: A pre/post implementation study design. SETTING: A 22-bed mixed surgical and medical ICU. PATIENTS: Seven hundred two consecutive mechanically ventilated ICU patients from June 2010 to January 2013. INTERVENTIONS: Implementation of daily paired spontaneous awakening trials (daily sedation vacation plus spontaneous breathing trials) as a quality improvement project. MEASUREMENTS AND MAIN RESULTS: After implementation of our program, there was an increase in the mean Richmond Agitation Sedation Scale scores on weekdays of 0.88 (p < 0.0001) and an increase in the mean Richmond Agitation Sedation Scale scores on weekends of 1.21 (p < 0.0001). After adjusting for age, race, gender, severity of illness, primary diagnosis, and ICU, the incidence and prevalence of delirium did not change post implementation of the protocol (incidence: 23% pre vs 19.6% post; p = 0.40; prevalence: 66.7% pre vs 55.3% post; p = 0.06). The combined prevalence of delirium/coma decreased from 90.8% pre protocol implementation to 85% postimplementation (odds ratio, 0.505; 95% CI, 0.299-0.853; p = 0.01). CONCLUSIONS: Implementing a "Wake Up and Breathe Program" resulted in reduced sedation among critically ill mechanically ventilated patients but did not change the incidence or prevalence of delirium
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