2,393 research outputs found

    A Primer on Laplacian Dynamics in Directed Graphs

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    We analyze the asymptotic behavior of general first order Laplacian processes on digraphs. The most important ones of these are diffusion and consensus with both continuous and discrete time. We treat diffusion and consensus as dual processes. This is the first complete exposition of this material in a single work.Comment: 24 pages, 5 figures, summer-school/conference on mathematical modeling of complex systems in Pescara, 201

    Endolymphatic Sac Tumor

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    Masses occupying the retrolabyrinthine space are uncommon and most often represent paragangliomas, choroid plexus papilloma, endolymphatic sac tumors (ELSTs) or distant metastasis. ELSTs are rare, locally invasive tumors of the inner ear, with less than 300 cases reported in the literature. ELSTs are associated with von-Hippel Lindau (VHL) disease. Patients diagnosed with an ELST should undergo genetic testing for VHL disease, and individuals with confirmed VHL disease should be screened for ELST(s)

    A Comparison of Collaborative Practice and Teacher Leadership Between Low-Performing and High-Performing Rural Kentucky High Schools

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    This article reports the findings of the 2011 results of ‘very rural’ Kentucky high schools on the Teaching, Empowering, Leading and Learning (TELL) Survey to determine whether differences existed between high and low performing rural schools across specific survey items. Schools with ACT scores one standard deviation (or more) above their predicted value were compared to rural high schools where students’ ACT scores were one standard deviation (or more) below their predicted value. Beale Codes of seven through nine from the United States Department of Agriculture were used to identify very rural Kentucky high schools. Very rural high schools identified as high-performing demonstrated significantly different results on survey items related to a culture of collaboration and teacher leadership than rural high schools identified as low performing. The survey suggested that in high-performing schools, the principal and teachers supported each other in their development as instructional leaders, and established communication and collaboration skills with families and community stakeholders

    Method and Apparatus for Non-Destructive Evaluation of Materials

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    Methods and apparatus for characterizing composite materials for manufacturing quality assurance (QA), periodic inspection during the useful life, or for forensic analysis/material testing. System are provided that relate eddy-current sensor responses to the fiber layup of a composite structure, the presence of impact damage on a composite structure with or without a metal liner, volumetric stress within the composite, fiber tow density, and other NDE inspection requirements. Also provided are systems that determine electromagnetic material properties and material dimensions of composite materials from capacitive sensor inspection measurements. These properties are related to the presence of buried defects in non-conductive composite materials, moisture ingress, aging of the material due to service or environmental/thermal exposure, or changes in manufacturing quality

    Assessing Causes of Change in the Freshwater Mussels (Bivalvia: Unionidae) in the Black River, Ohio

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    Habitat destruction is believed to be the number one cause of the decline in unionid mussels. Around the world, cities, towns and agriculture alter the structure of watersheds, and the Black River in Ohio may be a typical example. We investigated the diversity and abundance of unionid mussels in this watershed and compared results to urbanization locations, to site-specific appearance of the habitat and to a 1997 fish survey, as host species are another factor important to the distribution of unionid mussels. Although shells were found for 21 species, only 11 of these species were found alive. Seven of the species represented only by shells occurred only in the urbanized lower main stem of the river and less than five shells were found for each. Most of these shells were old and worn. Furthermore, the present assemblage in the main stem varied from shells obtained at a nearby archeological site, and from a voucher set of species obtained at the turn of the 20th Century. Mussel communities higher in the river and those in tributaries were less diverse, but abundance of the species present was higher than in the main stem. A lack of fish hosts may limit mussel diversity, as hosts for several species present in the main stem do not reside higher in the watershed. Overall, mussel assemblages in the Black River appear typical for the region with relatively abundant, but low diversity communities upstream of the cities that line Lake Erie\u27s coast and diverse, but small and potentially threatened, populations in the urban regions

    Method and Apparatus for Non-Destructive Evaluation of Materials

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    Methods and apparatus for characterizing composite materials for manufacturing quality assurance (QA), periodic inspection during the useful life, or for forensic analysis/material testing. System are provided that relate eddy-current sensor responses to the fiber layup of a composite structure, the presence of impact damage on a composite structure with or without a metal liner, volumetric stress within the composite, fiber tow density, and other NDE inspection requirements. Also provided are systems that determine electromagnetic material properties and material dimensions of composite materials from capacitive sensor inspection measurements. These properties are related to the presence of buried defects in non-conductive composite materials, moisture ingress, aging of the material due to service or environmental/thermal exposure, or changes in manufacturing quality

    The X-Ray Properties of the Optically Brightest Mini-BAL Quasars from the Sloan Digital Sky Survey

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    We have compiled a sample of 14 of the optically brightest radio-quiet quasars (mim_{i}~≤\le~17.5 and zz~≥\ge~1.9) in the Sloan Digital Sky Survey Data Release 5 quasar catalog that have C IV mini-BALs present in their spectra. X-ray data for 12 of the objects were obtained via a Chandra snapshot survey using ACIS-S, while data for the other two quasars were obtained from archival XMM-Newton observations. Joint X-ray spectral analysis shows the mini-BAL quasars have a similar average power-law photon index (Γ≈1.9\Gamma\approx1.9) and level of intrinsic absorption (NH≲8×1021 cm−2N_H \lesssim 8\times 10^{21} \ {\rm cm}^{-2}) as non-BMB (neither BAL nor mini-BAL) quasars. Mini-BAL quasars are more similar to non-BMB quasars than to BAL quasars in their distribution of relative X-ray brightness (assessed with Δαox\Delta\alpha_{\rm ox}). Relative colors indicate mild dust reddening in the optical spectra of mini-BAL quasars. Significant correlations between Δαox\Delta\alpha_{\rm ox} and UV absorption properties are confirmed for a sample of 56 sources combining mini-BAL and BAL quasars with high signal-to-noise ratio rest-frame UV spectra, which generally supports models in which X-ray absorption is important in enabling driving of the UV absorption-line wind. We also propose alternative parametrizations of the UV absorption properties of mini-BAL and BAL quasars, which may better describe the broad absorption troughs in some respects.Comment: ApJ accepted; 21 pages, 11 figures, and 9 table

    One job, one deal...or not: do generations respond differently to psychological contract fulfillment?

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    This paper investigates generational differences in the relations between psychological contract fulfillment and work attitudes. Data were collected from a sample of 909 employees in the Dutch service sector. Structural equation modeling analyses were used to test the moderating effects of generational differences on the influence of psychological contract fulfillment on affective commitment and turnover intention. The relationship between psychological contract fulfillment and these work outcomes was moderated by generational differences. Furthermore, results indicate that different generations respond differently to different aspects of psychological contract fulfillment, such as career development, job content, organizational policies, social atmosphere and rewards. The study provides evidence that generational differences impact the reciprocal relationship between employer and employee. Results from this study suggest that Baby Boomers and Generation X may be more motivated by social atmosphere, whereas Generation Y may be more motivated by job content and career development. Fair organizational policies are particularly motivating to Generation X, and providing rewards, though more important to Generation Y, seem mostly unrelated to work outcomes. This article is the first to study the moderation of generational differences in the relationships between psychological contract fulfillment and work outcomes

    Material condition assessment with eddy current sensors

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    Eddy current sensors and sensor arrays are used for process quality and material condition assessment of conducting materials. In an embodiment, changes in spatially registered high resolution images taken before and after cold work processing reflect the quality of the process, such as intensity and coverage. These images also permit the suppression or removal of local outlier variations. Anisotropy in a material property, such as magnetic permeability or electrical conductivity, can be intentionally introduced and used to assess material condition resulting from an operation, such as a cold work or heat treatment. The anisotropy is determined by sensors that provide directional property measurements. The sensor directionality arises from constructs that use a linear conducting drive segment to impose the magnetic field in a test material. Maintaining the orientation of this drive segment, and associated sense elements, relative to a material edge provides enhanced sensitivity for crack detection at edges
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