623 research outputs found

    Paper Session III-A - The Crisis in Human Capital

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    If the United States is to regain the competitive edge, retain leadership in the international aerospace arena and achieve the national aerospace goals, we must have more well qualified scientists and engineers entering the workforce as well as the highly qualified technicians necessary to design, build, operate and maintain our aerospace hardware. The nation\u27s educational system is not keeping pace with this demand for scientists and engineers. The necessary workforce will not be available unless prompt action is taken to ensure it. This paper reviews shortfalls in our educational systems today, showing where the U.S. stands relative to the rest of the industrialized nations. The complex dimensions of these issues are discussed as well as initiatives that are in work around the country in an attempt to counteract some of the problems. The roles of aerospace workers as individuals and aerospace companies as major stakeholders in the nation\u27s future are addressed. Some of the more effective approaches to the enhancement of our educational system which could be supported by the aerospace community are highlighted

    Reshaping perspectives of deep-sea benthic function

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    Bioturbation is a key ecosystem function with a fundamental role in mediating major biogeochemical cycles. The intensity and depth of bioturbation is influenced by the taxa present, which is often a function of food supply. The deep sea is generally oligotrophic with sediments composed predominantly of small, shallow burrowing macrofauna (<10 cm). Human activity is increasingly introducing POC to the deep-sea, however, organic enrichment of the deep-sea, and the subsequent response of bioturbators is poorly understood. Here we present data on benthic function in deep-sea systems that have experienced organic enrichment. We show that organic enrichment enhances deep-sea bioturbation through larger, advanced successional taxa, and deeper bioturbation depths. Enhanced bioturbation in the deep-sea should confer positive ecosystem functions (nutrient recycling, microbiological activity, remineralization), but adherence to approaches and interpretations guided by the paradigm of small, shallow-burrowing infauna could significantly underestimate deep-sea benthic processes at a global scale

    Simultaneous interrogation of interferometric and Bragg grating sensors

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    We propose a new method for the simultaneous interrogation of conventional two-beam interferometers and Bragg grating sensors. The technique employs an unbalanced Mach-Zehnder interferometer illuminated by a single low coherence source, which acts as a wavelength-tunable source for the grating and as a path-matched filter for the Fizeau interferometer, thus providing a high phase resolution output for each sensor. The grating sensor demonstrates a dynamic strain resolution of ~0.05 Āµ.epsilon/āˆšHz at 20 Hz, while the interferometric phase resolution is better than 1 mrad/āˆšHz at 20 Hz, corresponding to an rms mirror displacement of 0.08 nm

    Performance analysis of peak tracking techniques for fiber Bragg grating interrogation systems

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    In this paper, we propose a spectral correlation-based technique for tracking the wavelength shift of a fiber Bragg grating. We compared this approach, by means of a Monte Carlo numerical simulation, to the typical peak tracking techniques applied in classic interrogation systems. As result, we obtained a considerable gain in terms of noise tolerance (about 20 dB), which can be further incremented by selecting large-bandwidth gratings. This permits to increase the power budget of a fiber Bragg grating interrogator without changing the optical layout, overcoming classical limitations of commercial and custom systems. Penalties due to the non-idealities have been evaluated through the same Monte Carlo approach. Finally, we discuss a practical application of the peak tracking techniques to a fiber Bragg grating-based weight sensor, in which we applied the spectral correlation to track both the Bragg wavelength position, spectral deformations due to high strain, and spectral non-linearity

    Autocompensating Quantum Cryptography

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    Quantum cryptographic key distribution (QKD) uses extremely faint light pulses to carry quantum information between two parties (Alice and Bob), allowing them to generate a shared, secret cryptographic key. Autocompensating QKD systems automatically and passively compensate for uncontrolled time dependent variations of the optical fiber properties by coding the information as a differential phase between orthogonally-polarized components of a light pulse sent on a round trip through the fiber, reflected at mid-course using a Faraday mirror. We have built a prototype system based on standard telecom technology that achieves a privacy-amplified bit generation rate of ~1000 bits/s over a 10-km optical fiber link. Quantum cryptography is an example of an application that, by using quantum states of individual particles to represent information, accomplishes a practical task that is impossible using classical means.Comment: 18 pages, 6 figures, 1 table. Submitted to the New Journal of Physic

    Increased brain activation during working memory processing after pediatric mild traumatic brain injury (mTBI).

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    Purpose: The neural substrate of post-concussive symptoms following the initial injury period after mild traumatic brain injury (mTBI) in pediatric populations remains poorly elucidated. This study examined neuropsychological, behavioral, and brain functioning in adolescents post-mTBI to assess whether persistent differences were detectable up to a year post-injury. Methods: Nineteen adolescents (mean age 14.7 years) who experienced mTBI 3ā€“12 months previously (mean 7.5 months) and 19 matched healthy controls (mean age 14.0 years) completed neuropsychological testing and an fMRI auditory-verbal N-back working memory task. Parents completed behavioral ratings. Results: No between-group differences were found for cognition, behavior, or N-back task performance, though the expected decreased accuracy and increased reaction time as task difficulty increased were apparent. However, the mTBI group showed significantly greater brain activation than controls during the most difficult working memory task condition. Conclusion: Greater working memory task-related activation was found in adolescents up to one year post-mTBI relative to controls, potentially indicating compensatory activation to support normal task performance. Differences in brain activation in the mTBI group so long after injury may indicate residual alterations in brain function much later than would be expected based on the typical pattern of natural recovery, which could have important clinical implications

    PomBase 2015: updates to the fission yeast database.

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    PomBase (http://www.pombase.org) is the model organism database for the fission yeast Schizosaccharomyces pombe. PomBase provides a central hub for the fission yeast community, supporting both exploratory and hypothesis-driven research. It provides users easy access to data ranging from the sequence level, to molecular and phenotypic annotations, through to the display of genome-wide high-throughput studies. Recent improvements to the site extend annotation specificity, improve usability and allow for monthly data updates. Both in-house curators and community researchers provide manually curated data to PomBase. The genome browser provides access to published high-throughput data sets and the genomes of three additional Schizosaccharomyces species (Schizosaccharomyces cryophilus, Schizosaccharomyces japonicus and Schizosaccharomyces octosporus)

    Decreased cerebral blood flow in chronic pediatric mild TBI: an MRI perfusion study

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    We evaluated cerebral blood flow (CBF) in chronic pediatric mild traumatic brain injury (mTBI) using arterial spin labeling (ASL) magnetic resonance imaging perfusion. mTBI patients showed lower CBF than controls in bilateral frontotemporal regions, with no between-group cognitive differences. Findings suggest ASL may be useful to assess functional abnormalities in pediatric mTBI

    PomBase: a comprehensive online resource for fission yeast.

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    PomBase (www.pombase.org) is a new model organism database established to provide access to comprehensive, accurate, and up-to-date molecular data and biological information for the fission yeast Schizosaccharomyces pombe to effectively support both exploratory and hypothesis-driven research. PomBase encompasses annotation of genomic sequence and features, comprehensive manual literature curation and genome-wide data sets, and supports sophisticated user-defined queries. The implementation of PomBase integrates a Chado relational database that houses manually curated data with Ensembl software that supports sequence-based annotation and web access. PomBase will provide user-friendly tools to promote curation by experts within the fission yeast community. This will make a key contribution to shaping its content and ensuring its comprehensiveness and long-term relevance
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