3,608 research outputs found

    The Joint Program Dilemma: Analyzing the Pervasive Role That Social Dilemmas Play in Undermining Acquisition Success

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    Tenth Annual Acquisition Research Symposium Acquisition ManagementExcerpt from the Proceedings of the Tenth Annual Acquisition Research Symposium Acquisition ManagementNaval Postgraduate School Acquisition Research ProgramPrepared for the Naval Postgraduate School, Monterey, CANaval Postgraduate School Acquisition Research ProgramApproved for public release; distribution is unlimited

    CHIRON - A Fiber Fed Spectrometer for Precise Radial Velocities

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    The CHIRON optical high-resolution echelle spectrometer was commissioned at the 1.5m telescope at CTIO in 2011. The instrument was designed for high throughput and stability, with the goal of monitoring radial velocities of bright stars with high precision and high cadence for the discovery of low-mass exoplanets. Spectral resolution of R=79,000 is attained when using a slicer with a total (including telescope and detector) efficiency of 6% or higher, while a resolution of R=136,000 is available for bright stars. A fixed spectral range of 415 to 880 nm is covered. The echelle grating is housed in a vacuum enclosure and the instrument temperature is stabilized to +-0.2deg. Stable illumination is provided by an octagonal multimode fiber with excellent light-scrambling properties. An iodine cell is used for wavelength calibration. We describe the main optics, fiber feed, detector, exposure-meter, and other aspects of the instrument, as well as the observing procedure and data reduction.Comment: 15 pages, 10 figures. Accepted by PAS

    Lightweight XML-based query, integration and visualization of distributed, multimodality brain imaging data

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    A need of many neuroimaging researchers is to integrate multimodality brain data that may be stored in separate databases. To address this need we have developed a framework that provides a uniform XML-based query interface across multiple online data sources. The development of this framework is driven by the need to integrate neurosurgical and neuroimaging data related to language. The data sources for the language studies are 1) a web-accessible relational database of neurosurgical cortical stimulation mapping data (CSM) that includes patient-specific 3-D coordinates of each stimulation site mapped to an MRI reconstruction of the patient brain surface; and 2) an XML database of fMRI and structural MRI data and analysis results, created automatically by a batch program we have embedded in SPM. To make these sources available for querying each is wrapped as an XML view embedded in a web service. A top level web application accepts distributed XQueries over the sources, which are dispatched to the underlying web services. Returned results can be displayed as XML, HTML, CSV (Excel format), a 2-D schematic of a parcellated brain, or a 3-D brain visualization. In the latter case the CSM patient-specific coordinates returned by the query are sent to a transformation web-service for conversion to normalized space, after which they are sent to our 3-D visualization program MindSeer, which is accessed via Java WebStart through a generated link. The anatomical distribution of pooled CSM sites can then be visualized using various surfaces derived from brain atlases. As this framework is further developed and generalized we believe it will have appeal for researchers who wish to query, integrate and visualize results across their own databases as well as those of collaborators

    Sex differences in eye gaze and symbolic cueing of attention

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    Observing a face with averted eyes results in a reflexive shift of attention to the gazed-at location. Here we present results that show that this effect is weaker in males than in females (Experiment 1). This result is predicted by the ‘extreme male brain’ theory of autism (Baron-Cohen, 2003), which suggests that males in the normal population should display more autism-like traits than females (e.g., poor joint attention). Indeed, participants′ scores on the Autism-Spectrum Quotient (Baron-Cohen, Wheelwright, Stott, Bolton, & Goodyear, 2001) negatively correlated with cueing magnitude. Furthermore, exogenous orienting did not differ between the sexes in two peripheral cueing experiments (Experiments 2a and 2b). However, a final experiment showed that using non-predictive arrows instead of eyes as a central cue also revealed a large gender difference. This demonstrates that reduced orienting from central cues in males generalizes beyond gaze cues. These results show that while peripheral cueing is equivalent in the male and female brains, the attention systems of the two sexes treat noninformative symbolic cues very differently

    Hydrodynamic electron flow and Hall viscosity

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    The authors acknowledge support from the Emergent Phenomena in Quantum Systems initiative of the Gordon and Betty Moore Foundation (T. S.) and NSF DMR-1507141 and a Simons Investigatorship (J. E. M.). We also acknowledge the support of the Max Planck Society and the UK Engineering and Physical Sciences Research Council under Grant No. EP/I032487/1.In metallic samples of small enough size and sufficiently strong momentum-conserving scattering, the viscosity of the electron gas can become the dominant process governing transport. In this regime, momentum is a long-lived quantity whose evolution is described by an emergent hydrodynamical theory. Furthermore, breaking time-reversal symmetry leads to the appearance of an odd component to the viscosity called the Hall viscosity, which has attracted considerable attention recently due to its quantized nature in gapped systems but still eludes experimental confirmation. Based on microscopic calculations, we discuss how to measure the effects of both the even and odd components of the viscosity using hydrodynamic electronic transport in mesoscopic samples under applied magnetic fields.PostprintPeer reviewe

    Individualised pelvic floor muscle training in women with pelvic organ prolapse: a multicentre randomised controlled trial

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    <br>Background: Pelvic organ prolapse is common and is strongly associated with childbirth and increasing age. Women with prolapsed are often advised to do pelvic floor muscle exercises, but supporting evidence is limited. Our aim was to establish if one-to-one individualised pelvic floor muscle training (PFMT) is effective in reducing prolapse symptoms.</br> <br>Methods: A parallel‐group multicentre randomised controlled trial (ISRCTN35911035) in female outpatients with newly-diagnosed, symptomatic stage I, II or III prolapse, comparing five PFMT appointments over 16 weeks (n=225) versus a lifestyle advice leaflet (n=222). Treatment allocation was by remote computer allocation using minimisation. Our primary endpoint was participants’ self-report of prolapsed symptoms at 12 months. Group assignment was masked from outcome assessors. We compared outcomes between trial groups in an intention-to-treat analysis. The cost of PFMT and savings on subsequent treatments were calculated to estimate cost-effectiveness.</br> <br>Findings: Compared to the control group, the intervention group reported fewer prolapse symptoms at 12 months (mean difference between groups in change score 1.52, 95% CI [0.46, 2.59], p=0.0053); reported their prolapse to be “better” more often (57.2% versus 44.7%, difference 12.6%, 95% CI [1.1%, 24.1%], p=0.0336); and had an increased but non-significant odds of having less severe stage of prolapse at their 6-month clinical examination, (OR 1.47, 95% CI [0.97, 2.27], p=0.07). The control group had a greater uptake of other prolapse treatment (49.6% versus 24.1%, difference 25.5%, 95% CI [14.5%, 36.0%], p <0.0001). Findings were robust to missing data. The net cost of the 25 intervention was £131.61 per woman and the cost per one-point reduction in the symptom score was £86.59, 95% CI [£50.81, £286.11]. </br&gt

    The Enduring Effects of Parental Alcohol, Tobacco, and Drug Use on Child Well-being: A Multilevel Meta-Analysis

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    The effects of psychoactive substance abuse are not limited to the user, but extend to the entire family system, with children of substance abusers being particularly at risk. This meta-analysis attempted to quantify the longitudinal relationship between parental alcohol, tobacco, and drug use and child well-being, investigating variation across a range of substance and well-being indices and other potential moderators. We performed a literature search of peer-reviewed, English language, longitudinal observational studies that reported outcomes for children aged 0 to 18 years. In total, 56 studies, yielding 220 dependent effect sizes, met inclusion criteria. A multilevel random-effects model revealed a statistically significant, small detriment to child well-being for parental substance abuse over time (r = .15). Moderator analyses demonstrated that the effect was more pronounced for parental drug use (r = .25), compared with alcohol use (r = .13), tobacco use (r = .13), and alcohol use disorder (r = .14). Results highlight a need for future studies that better capture the effect of parental psychoactive substance abuse on the full breadth of childhood well-being outcomes and to integrate substance abuse into models that specify the precise conditions under which parental behavior determines child well-being
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