5,972 research outputs found

    Sex Differences in Internalizing and Externalizing Behaviors in Children with Autism Spectrum Disorder

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    This study used a retrospective practice-based research method to compare levels of internalizing and externalizing behaviors of a clinically-ascertained sample of young children with autism spectrum disorder (ASD; n=90). As measured by the Child Behavior Checklist (CBCL), internalizing and externalizing behaviors were compared to normative behavior, and between boys and girls with ASD. Findings suggest that in a clinical sample, children with ASD are more likely than typically developing children to have internalizing and/or externalizing problems. No significant sex differences were found for Internalizing Problems, Externalizing Problems, or Total Problems scores on either the parent or teacher versions of the CBCL. These findings may help clinicians better understand how children with ASD are affected by co-morbid psychiatric disorders, and could help to inform diagnosis and intervention

    Investigation of Residual Strength and Fatigue Life of Unstiffened Aluminum Panels with Multiple Site Damage

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    Multiple Site Damage MSD is the occurrence of small fatigue cracks at several sites within aircraft structures. This is important since it may lower the residual strength and fatigue life of the structure beyond what can be predicted using the damage tolerance technique based on a single crack, currently in use to design aircraft structures. This study investigated the effects of MSD on unstiffined panels. MSD usually occurs at rivet holes, or other stress concentration locations within an aircraft structure. This study simulated rivet holes with MSD, by using holes of constant diameter with small cracks, evenly spaced across the midspan of specimens. The objective of the study was to test the validity of the available analytical methods to predict the residual strength and fatigue life of panels with MSD. Residual strengths of large specimens with MSD were measured in two different configurations to test the applicability of five failure criteria. A total of ten residual Fatigue tests were also conducted in three configurations to test the ability of analytical methods to predict fatigue life. The analytical methods investigated in this study can provide an aircraft designer with a conservative estimate of the residual strength of aircraft structures with MSD damage. However, the three failure criteria considered in this study produced unconservative fatigue life predictions

    Individual and institutional determinants of the male female wage gap among U.S. economics faculty

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    This paper provides new evidence on the male female wage gap in academia. Using unique data from the economics discipline, we estimate a human-capital based model to explore the nature of wage differentials among male and female economics professors. Results indicate the salary gap varies across systematically across individual and institutional characteristics.discrimination, wages, academia

    Energy efficient engine. Low pressure turbine test hardware detailed design report

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    The low pressure turbine for the energy efficient engine is a five-stage configuration with moderate aerodynamic loading incorporating advanced features of decambered airfoils and extended blade overlaps at platforms and shrouds. Mechanical integrity of 18,000 hours on flowpath components and 36,000 hours on all other components is achieved along with no aeromechanical instabilities within the steady-state operating range. Selection of a large number (156) of stage 4 blades, together with an increased stage 4 vane-to-blade gap, assists in achieving FAR 36 acoustic goals. Active clearance control (ACC) of gaps at blade tips and interstage seals is achieved by fan air cooling judiciously applied at responsive locations on the casing. This ACC system is a major improvement in preventing deterioration of the 0.0381 cm (0.015 in.) clearances required to meet the integrated-core/low-spool turbine efficiency goal of 91.1% and the light propulsion system efficiency goal of 91.7%

    Influence of statistical fluctuations on K/πK/\pi ratios in relativistic heavy ion collisions

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    The influence of pure statistical fluctuations on K/πK/\pi ratio is investigated in an event-by-event way. Poisson and the modified negative binomial distributions are used as the multiplicity distributions since they both have statistical background. It is shown that the distributions of the ratio in these cases are Gaussian, and the mean and relative variance are given analytically.Comment: 6 pages in RevTeX, 3 eps figures include

    Comparison of Three Different Image Forces for Active Contours on Abdominal Image Boundary Detection

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    Active contour, or snake, is an energy minimizing spline that is useful in image boundary detection. Active contours are stimulated by internal forces, image forces and external forces which maintain the shape of the contours while attract the contours to some desired features, usually edges. Problems in implementing active contours such as convergence and initialization have motivated researchers to modify image forces of the active contours. This paper presents a comparative study among three different image forces: traditional snakes, balloon and gradient vector flow (GVF). The study is validated by experiments on abdominal image boundaries detection. These lead to the conclusion that GVF gives the most appropriate results among the other approaches

    Radiolabeling human peripheral blood stem cells for positron emission tomography (PET) imaging in young rhesus monkeys.

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    These studies focused on a new radiolabeling technique with copper ((64)Cu) and zirconium ((89)Zr) for positron emission tomography (PET) imaging using a CD45 antibody. Synthesis of (64)Cu-CD45 and (89)Zr-CD45 immunoconjugates was performed and the evaluation of the potential toxicity of radiolabeling human peripheral blood stem cells (hPBSC) was assessed in vitro (viability, population doubling times, colony forming units). hPBSC viability was maintained as the dose of (64)Cu-TETA-CD45 increased from 0 (92%) to 160 ”Ci/mL (76%, p>0.05). Radiolabeling efficiency was not significantly increased with concentrations of (64)Cu-TETA-CD45 >20 ”Ci/mL (p>0.50). Toxicity affecting both growth and colony formation was observed with hPBSC radiolabeled with ≄40 ”Ci/mL (p<0.05). For (89)Zr, there were no significant differences in viability (p>0.05), and a trend towards increased radiolabeling efficiency was noted as the dose of (89)Zr-Df-CD45 increased, with a greater level of radiolabeling with 160 ”Ci/mL compared to 0-40 ”Ci/mL (p<0.05). A greater than 2,000 fold-increase in the level of (89)Zr-Df-CD45 labeling efficiency was observed when compared to (64)Cu-TETA-CD45. Similar to (64)Cu-TETA-CD45, toxicity was noted when hPBSC were radiolabeled with ≄40 ”Ci/mL (p<0.05) (growth, colony formation). Taken together, 20 ”Ci/mL resulted in the highest level of radiolabeling efficiency without altering cell function. Young rhesus monkeys that had been transplanted prenatally with 25×10(6) hPBSC expressing firefly luciferase were assessed with bioluminescence imaging (BLI), then 0.3 mCi of (89)Zr-Df-CD45, which showed the best radiolabeling efficiency, was injected intravenously for PET imaging. Results suggest that (89)Zr-Df-CD45 was able to identify engrafted hPBSC in the same locations identified by BLI, although the background was high

    Wind Turbines and Coastal Recreation Demand

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    We examine the impact of coastal wind turbines on coastal tourism and recreation for residents of the northern CAMA counties in North Carolina. A combination of telephone and web survey data are used to assess the impact of coastal wind farms on trip behavior and site choice. Most of the respondents to our telephone survey claim to support offshore wind energy development, and independent survey data suggest that the observed levels of support may be indicative of the broader population in this region. Overall, we find very little impact of coastal wind turbines on aggregate recreational visitation; loss in consumer surplus associated with wide spread wind development in the coastal zone is insignificant at 17(orabout1.517 (or about 1.5%). Results suggest that NC coastal residents are averse to wind farms in the near-shore zone; average compensating variation for wind farms one mile from the shore is estimated at 55 per household. On average, we find no evidence of aversion to wind farms 4 miles out in the ocean, or for wind farms located in coastal estuaries. For all wind farm scenarios, we find evidence of preference heterogeneity– some respondents find this appealing while others find it aversive. Key Words: Recreation demand, tourism, renewable energy
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