15,222 research outputs found

    Digital computer processing of LANDSAT data for North Alabama

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    Computer processing procedures and programs applied to Multispectral Scanner data from LANDSAT are described. The output product produced is a level 1 land use map in conformance with a Universal Transverse Mercator projection. The region studied was a five-county area in north Alabama

    A study and evaluation of image analysis techniques applied to remotely sensed data

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    An analysis of phenomena causing nonlinearities in the transformation from Landsat multispectral scanner coordinates to ground coordinates is presented. Experimental results comparing rms errors at ground control points indicated a slight improvement when a nonlinear (8-parameter) transformation was used instead of an affine (6-parameter) transformation. Using a preliminary ground truth map of a test site in Alabama covering the Mobile Bay area and six Landsat images of the same scene, several classification methods were assessed. A methodology was developed for automatic change detection using classification/cluster maps. A coding scheme was employed for generation of change depiction maps indicating specific types of changes. Inter- and intraseasonal data of the Mobile Bay test area were compared to illustrate the method. A beginning was made in the study of data compression by applying a Karhunen-Loeve transform technique to a small section of the test data set. The second part of the report provides a formal documentation of the several programs developed for the analysis and assessments presented

    Classification software technique assessment

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    A catalog of software options is presented for the use of local user communities to obtain software for analyzing remotely sensed multispectral imagery. The resources required to utilize a particular software program are described. Descriptions of how a particular program analyzes data and the performance of that program for an application and data set provided by the user are shown. An effort is made to establish a statistical performance base for various software programs with regard to different data sets and analysis applications, to determine the status of the state-of-the-art

    The effect of uniaxial pressure on the magnetic anisotropy of the Mn_{12}-Ac single-molecule magnet

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    We study the effect of uniaxial pressure on the magnetic hysteresis loops of the single-molecule magnet Mn_{12}-Ac. We find that the application of pressure along the easy axis increases the fields at which quantum tunneling of magnetization occurs. The observations are attributed to an increase in the molecule's magnetic anisotropy constant D of 0.142(1)%/kbar. The increase in D produces a small, but measurable increase in the effective energy barrier for magnetization reversal. Density-functional theory calculations also predict an increase in the barrier with applied pressure.Comment: version accepted by EPL; 6 pages, including 7 figures. Small changes and added reference

    Haptoglobin genotype, haemoglobin and malaria in Gambian children

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    Dark Solitons in Discrete Lattices: Saturable versus Cubic Nonlinearities

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    In the present work, we study dark solitons in dynamical lattices with the saturable nonlinearity and compare them with those in lattices with the cubic nonlinearity. This comparison has become especially relevant in light of recent experimental developments in the former context. The stability properties of the fundamental waves, for both on-site and inter-site modes, are examined analytically and corroborated by numerical results. Furthermore, their dynamical evolution when they are found to be unstable is obtained through appropriately crafted numerical experiments.Comment: 15 pages, 5 figure

    Rhinovirus-16 increases ATP release in A549 cells without concomitant increase in production

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    Human rhinovirus (RV) is the most common cause of upper respiratory tract infection (URTI) and chronic airway disease exacerbation. Cough is present in 50–80% of URTI cases, accompanied by heightened airway hypersensitivity, yet no effective treatment currently exists for this infectious cough. The mechanism by which RV causes cough and airway hypersensitivity in URTI is still unknown despite recent advances in potential therapies for chronic cough.The effect of RV-16 infection (MOI 1) on intracellular ATP stores and ATP release in A549 alveolar epithelial cells was measured.RV-16 infection was found to significantly increase (by 50% from basal at 24 h) followed by decrease (by 50% from basal at 48 and 72 h) intracellular ATP concentrations, while increasing ATP release (from 72 h) independently of secondary stimulation. This effect was mimicked by intercellular adhesion molecule 1 receptor binding alone through ultraviolet-inactivated sham control. In addition, RV-16-infected cells became more sensitive to secondary stimulation with both hypotonic and isotonic solutions, suggestive of a hypersensitive response. These responses were not mediated via increased TRPV4 or pannexin-1 whole-cell expression as determined by Western blotting. Interestingly, the increased ATP release seen was not a result of increased mitochondrial ATP production.Thus, this is the first report demonstrating that RV-16 infection of airway epithelial cells causes hypersensitivity by increasing ATP release. These finding provide a novel insight into the process by which viruses may cause cough and identify a potential target for treatment of viral and post-viral cough

    Effect of Interband Transitions on the c axis Penetration Depth of Layered Superconductors

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    The electromagnetic response of a system with two planes per unit cell involves, in addition to the usual intraband contribution, an added interband term. These transitions affect the temperature dependence and the magnitude of the zero temperature c-axis penetration depth. When the interplane hopping is sufficiently small, the interband transitions dominate the low temperature behaviour of the penetration depth which then does not reflect the linear temperature dependence of the intraband term and in comparison becomes quite flat even for a d-wave gap. It is in this regime that the pseudogap was found in our previous normal state calculations of the c-axis conductivity, and the effects are connected.Comment: 8 pages, 5 figure

    Meteoroid and debris special investigation group data acquisition procedures

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    The entire LDEF spacecraft was examined by M&D SIG for impact (i.e., craters greater than or = 0.5 mm and penetrations greater than or = 0.3 mm in diameter) and related features (e.g., debris, secondaries). During the various detailed surveys conducted at NASA Kennedy, approx. 5,000 impact related features were photodocumented, and their locations measured and recorded; an additional approx. 30,000 smaller features were counted. The equipment and techniques used by the M&D SIG permitted the determination and recording of the locations and diameters of the 5,000 imaged features. A variety of experimental and LDEF structural hardware was acquired by the M&D SIG and is presently being examined and curated at NASA Johnson
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