520 research outputs found

    Theory and operation of the real-time data acquisition system for the NASA-LaRC differential absorption lidar (DIAL)

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    The improvement of computer hardware and software of the NASA Multipurpose Differential Absorption Lidar (DIAL) system is documented. The NASA DIAL system has undergone development and experimental deployment at NASA/Langley Res. Center for the remote measurement of atmospheric trace gas concentrations from ground and aircraft platforms. A viable DIAL system was developed capable of remotely measuring O3 and H2O concentrations from an aircraft platform. The DIAL Data Acquisition System (DAS) has undergone a number of improvements also. Due to the participation of the DIAL in the Global Tropospheric Experiment, modifications and improvements of the system were tested and used both in the lab and in air. Therefore, this is an operational manual for the DIAL DAS

    Pennsylvanian Spiriferacea and Spiriferinacea of Kansas

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    36 p., 22 fig.http://paleo.ku.edu/contributions.htm

    Segregation and Tiebout Sorting: Investigating the Link between Investments in Public Goods and Neighborhood Tipping

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    Segregation has been a recurring social concern throughout human history. While much progress has been made to our understanding of the mechanisms driving segregation, work to date has ignored the role played by location-specific amenities. Nonetheless, policy remedies for reducing group inequity often involve place-based investments in minority communities. In this paper, we introduce an exogenous location-specific public good into a model of group segregation. We characterize the equilibria of the model and derive the comparative statics of improvements to the local public goods. We show that the dynamics of neighborhood tipping depend on the levels of public goods. We also show that investments in low-public good communities can actually increase segregation.

    Reassessment of vertebrate ichnotaxa from the Upper Carboniferous ā€˜Fern Ledgesā€™, Lancaster Formation, Saint John, New Brunswick, Canada

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    Vertebrate ichnotaxa described by George Frederic Matthew in 1910 from the Upper Carboniferous (Lower Pennsylvanian) ā€˜Fern Ledgesā€™ of Saint John, New Brunswick, were dismissed as dubious trackways by previous authors. Thus, three new ichnospecies Matthew described appeared in the 1975 Treatise on Invertebrate Paleontology as ā€œunrecognized or unrecognizableā€ and were mostly forgotten by vertebrate ichnologists. These traces include Hylopus (?) variabilis, Nanopus (?) vetustus and Bipezia bilobata. One ichnospecies, Hylopus (?) variabilis, here is retained as a valid tetrapod footprint ichnotaxon and reassigned to the ichnogenus Limnopus as a new combination, together with other poorly preserved specimens Matthew labeled, but never described. Nanopus (?) vetustus and Bipezia bilobata named by Matthew in the same paper, have been reexamined and remain as nomina dubia.

    A Novel Diagnostic Aid for Detection of Intra-Abdominal Adhesions to the Anterior Abdominal Wall Using Dynamic Magnetic Resonance Imaging

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    Introduction. Abdominal adhesions can cause serious morbidity and complicate subsequent operations. Their diagnosis is often one of exclusion due to a lack of a reliable, non-invasive diagnostic technique. Development and testing of a candidate technique are described below. Method. During respiration, smooth visceral sliding motion occurs between the abdominal contents and the walls of the abdominal cavity. We describe a technique involving image segmentation and registration to calculate shear as an analogue for visceral slide based on the tracking of structures throughout the respiratory cycle. The presence of an adhesion is attributed to a resistance to visceral slide resulting in a discernible reduction in shear. The abdominal movement due to respiration is captured in sagittal dynamic MR images. Results. Clinical images were selected for analysis, including a patient with a surgically confirmed adhesion. Discernible reduction in shear was observed at the location of the adhesion while a consistent, gradually changing shear was observed in the healthy volunteers. Conclusion. The technique and its validation show encouraging results for adhesion detection but a larger study is now required to confirm its potential

    Investigative Ophthalmology (j Visual Science Articles Membrane Skeleton Protein 4.1 in Inner Segments of Retinal Cones

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    The role of the spectrin-based membrane skeleton in regulation of cell morphology and immobilization of integral membrane proteins is well established in erythrocytes and is currently being investigated in other eukaryotic cells
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