2,453 research outputs found

    Analysis and correlation of the test data from an advanced technology rotor system

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    Comparisons were made of the performance and blade vibratory loads characteristics for an advanced rotor system as predicted by analysis and as measured in a 1/5 scale model wind tunnel test, a full scale model wind tunnel test and flight test. The accuracy with which the various tools available at the various stages in the design/development process (analysis, model test etc.) could predict final characteristics as measured on the aircraft was determined. The accuracy of the analyses in predicting the effects of systematic tip planform variations investigated in the full scale wind tunnel test was evaluated

    Inspections To Avert Terrorism: Robustness Under Severe Uncertainty

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    Protecting against terrorist attacks requires making decisions in a world in which attack probabilities are largely unknown. The potential for very large losses encourages a conservative perspective, in particular toward decisions that are robust. But robustness, in the sense of assurance against extreme outcomes, ordinarily is not the only desideratum in uncertain environments. We adopt Yakov Ben-Haim’s (2001b) model of information gap decision making to investigate the problem of inspecting a number of similar targets when one of the targets may be attacked, but with unknown probability. We apply this to a problem of inspecting a sample of incoming shipping containers for a terrorist weapon. While it is always possible to lower the risk of a successful attack by inspecting more vessels, we show that robustness against the failure to guarantee a minimum level of expected utility might not be monotonic. Robustness modeling based on expected utility and incorporating inspection costs yields decision protocols that are a useful alternative to traditional risk analysis.Terrorism, Robustness, Severe Uncertainty, Port Security

    Optical vernier technique for in-situ measurement of the length of long Fabry-Perot cavities

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    We propose a method for in-situ measurement of the length of kilometer size Fabry-Perot cavities in laser gravitational wave detectors. The method is based on the vernier, which occurs naturally when the laser incident on the cavity has a sideband. By changing the length of the cavity over several wavelengths we obtain a set of carrier resonances alternating with sideband resonances. From the measurement of the separation between the carrier and a sideband resonance we determine the length of the cavity. We apply the technique to the measurement of the length of a Fabry-Perot cavity in the Caltech 40m Interferometer and discuss the accuracy of the technique.Comment: LaTeX 2e, 12 pages, 4 figure

    The effects of early-treated phenylketonuria on volumetric measures of the cerebellum

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    Past murine studies of phenylketonuria (PKU) have documented significant effects on cerebellum at both the gross and cellular levels. The profile of neurocognitive and motor difficulties associated with early-treated PKU (ETPKU) is also consistent with potential cerebellar involvement. Previous neuroanatomical studies of cerebellum in patients with PKU, however, have yielded mixed results. The objective of the present study was to further examine potential differences in cerebellar morphometry between individuals with and without ETPKU. To this end, we analyzed high resolution T1-weighted MR images from a sample of 20 individuals with ETPKU and an age-matched comparison group of 20 healthy individuals without PKU. Measurements of whole brain volume, whole cerebellum volume, cerebellar gray matter volume, and cerebellar white matter volume were collected by means of semiautomatic volumetric analysis. Data analysis revealed no significant group differences in whole brain volume, whole cerebellar volume, or cerebellar white matter volume. A significant reduction in cerebellar gray matter volume, however, was observed for the ETPKU group compared to the non-PKU comparison group. These findings expand on previous animal work suggesting that cerebellar gray matter is impacted by PKU. It is also consistent with the hypothesis that the cognitive difficulties experienced by individuals with ETPKU may be related to disruptions in gray matter. Additional studies are needed to fully elucidate the timing and extent of the impact of ETPKU on cerebellum and the associated neurocognitive consequences

    Effect of propranolol on facial processing in autism spectrum disorder

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    Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by social interaction deficits, communication impairments, and restricted, repetitive behaviors. ASD, with estimates of incidence as high as 1 in 88 individuals, has a largely unknown etiology. Pharmacological intervention is currently being explored to improve symptoms of ASD, including those in the social domain. Social interaction deficits in this population may include facial processing abnormalities, such as reduced eye contact, and increased fixation on less socially-salient facial regions, such as the mouth. However, there is variability in the degree of these deficits in the current literature. Additionally, it has been previously hypothesized that stress mediates poor facial processing in individuals with ASD. This pilot study examines the effect of propranolol, a nonselective beta-adrenergic antagonist anxiolytic, on facial processing in individuals with ASD and typically developing controls

    Incidence of Readmission Following Pediatric Hand Surgery: An Analysis of 6600 Patients

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    BACKGROUND: Quality in surgical outcomes is frequently assessed by the 30-day readmission rate. There are limited data available in the published literature regarding readmission rates following pediatric hand surgery. This study aims to identify factors associated with an increased risk of readmission following hand surgery in a pediatric population. METHODS: The 2012-2017 National Surgical Quality Improvement Project - Pediatric (NSQIP-P) databases were queried for pediatric patients who underwent procedures with hand-specific current procedural terminology (CPT) codes. The primary outcome was readmission. RESULTS: A total of 6600 pediatric patients were identified and included in the analysis. There were 45 patients who were readmitted in the study cohort, giving an overall readmission rate of 0.68%. The median time to readmission was 12 (IQR 5-20) days. On univariate analysis, factors associated with readmission included younger age, smaller size, prematurity, higher American Society of Anesthesiologists (ASA) class, inpatient admission at index operation, and longer anesthesia and operative times. Complex syndactyly repair was also associated with higher readmission rates. On multivariate analysis, ASA class 3 or 4 and inpatient surgery remained significant predictors of readmission. CONCLUSIONS: Overall, pediatric hand surgery is associated with a very low risk of 30-day readmission. Higher ASA class and inpatient surgery increase patients\u27 risk for readmission. In particular, complex syndactyly repair is associated with a higher risk of readmission than other hand procedures. This information is useful in surgical planning and preoperative counseling of parents

    Expressive and Instrumental Offending: Reconciling the Paradox of Specialisation and Versatility

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    Although previous research into specialisation has been dominated by the debate over the existence of specialisation versus versatility, it is suggested that research needs to move beyond the restrictions of this dispute. The current study explores the criminal careers of 200 offenders based on their criminal records, obtained from a police database in the North West of England, aiming to understand the patterns and nature of specialisation by determining the presence of differentiation within their general offending behaviours and examining whether the framework of Expressive and Instrumental offending styles can account for any specialised tendencies that emerge. Fifty-eight offences were subjected to Smallest Space Analysis. Results revealed that a model of criminal differentiation could be identified and that any specialisation is represented in terms of Expressive and Instrumental offending styles

    Continuous GPS Observations of Postseismic Deformation Following the 16 October 1999 Hector Mine, California, Earthquake (M_w 7.1)

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    Rapid field deployment of a new type of continuously operating Global Positioning System (GPS) network and data from Southern California Integrated GPS Network (SCIGN) stations that had recently begun operating in the area allow unique observations of the postseismic deformation associated with the 1999 Hector Mine earthquake. Innovative solutions in fieldcraft, devised for the 11 new GPS stations, provide high-quality observations with 1-year time histories on stable monuments at remote sites. We report on our results from processing the postseismic GPS data available from these sites, as well as 8 other SCIGN stations within 80 km of the event (a total of 19 sites). From these data, we analyze the temporal character and spatial pattern of the postseismic transients. Data from some sites display statistically significant time variation in their velocities. Although this is less certain, the spatial pattern of change in the postseismic velocity field also appears to have changed. The pattern now is similar to the pre-Landers (pre-1992) secular field, but laterally shifted and locally at twice the rate. We speculate that a 30 km × 50 km portion of crust (near Twentynine Palms), which was moving at nearly the North American plate rate (to within 3.5 mm/yr of that rate) prior to the 1992 Landers sequence, now is moving along with the crust to the west of it, as though it has been entrained in flow along with the Pacific Plate as a result of the Landers and Hector Mine earthquake sequence. The inboard axis of right-lateral shear deformation (at lower crustal to upper mantle depth) may have jumped 30 km farther into the continental crust at this fault junction that comprises the southern end of the eastern California shear zone

    Early risk factors for adolescent antisocial behaviour: an Australian longitudinal study

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    Objective: This investigation utilizes data from an Australian longitudinal study to identify early risk factors for adolescent antisocial behaviour. Method: Analyses are based on data from the Mater University Study of Pregnancy, an on-going longitudinal investigation of women’s and children’s health and development involving over 8000 participants. Five types of risk factors (child characteristics, perinatal factors, maternal/familial characteristics, maternal pre- and post-natal substance use and parenting practices) were included in analyses and were based on maternal reports, child assessments and medical records. Adolescent antisocial behaviour was measured when children were 14 years old, using the delinquency subscale of the Child Behaviour Checklist. Results: Based on a series of logistic regression models, significant risk factors for adolescent antisocial behaviour included children’s prior problem behaviour (i.e. aggression and attention/restlessness problems at age 5 years) and marital instability, which doubled or tripled the odds of antisocial behaviour. Perinatal factors, maternal substance use, and parenting practices were relatively poor predictors of antisocial behaviour. Conclusions: Few studies have assessed early predictors of antisocial behaviour in Australia and the current results can be used to inform prevention programs that target risk factors likely to lead to problem outcomes for Australian youth
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