4,594 research outputs found

    Development of an intelligent interface for adding spatial objects to a knowledge-based geographic information system

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    Earth Scientists lack adequate tools for quantifying complex relationships between existing data layers and studying and modeling the dynamic interactions of these data layers. There is a need for an earth systems tool to manipulate multi-layered, heterogeneous data sets that are spatially indexed, such as sensor imagery and maps, easily and intelligently in a single system. The system can access and manipulate data from multiple sensor sources, maps, and from a learned object hierarchy using an advanced knowledge-based geographical information system. A prototype Knowledge-Based Geographic Information System (KBGIS) was recently constructed. Many of the system internals are well developed, but the system lacks an adequate user interface. A methodology is described for developing an intelligent user interface and extending KBGIS to interconnect with existing NASA systems, such as imagery from the Land Analysis System (LAS), atmospheric data in Common Data Format (CDF), and visualization of complex data with the National Space Science Data Center Graphics System. This would allow NASA to quickly explore the utility of such a system, given the ability to transfer data in and out of KBGIS easily. The use and maintenance of the object hierarchies as polymorphic data types brings, to data management, a while new set of problems and issues, few of which have been explored above the prototype level

    Psychological type preferences of male British Assemblies of God Theological College students: tough-minded or tender-hearted?

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    Psychological type theory proposes that people make decisions through using one of two dichotomous judging functions (thinking and feeling). People who prefer thinking make judgements based on impersonal logic and tend to be objective and tough-minded, while people who prefer feeling make judgements based on personal values and tend to be compassionate and tender-hearted. This study explores the notion that the judging functions are key predictors of individual differences in terms of religiosity. The psychological type preferences of a sample of 190 male Assemblies of God bible college students were assessed using Form G (Anglicised) of the Myers-Briggs Type Indicator. The data revealed preferences for thinking over feeling, and the implications of this finding are explored

    The influence of the hydrologic cycle on the extent of sea ice with climatic implications

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    Multi-temporal satellite images, field observations, and field measurements were used to investigate the mechanisms by which sea ice melts offshore from the Mackenzie River delta. Advanced Very High Resolution Radiometer (AVHRR) satellite data recorded in 1986 were analyzed. The satellite data were geometrically corrected and radiometrically calibrated so that albedo and temperature values could be extracted. The investigation revealed that sea ice melted approximately 2 weeks earlier offshore from the Mackenzie River delta than along coasts where river discharge is minimal or non-existent. There is significant intra-delta variability in the timing and patterns of ice melt. An estimation of energy flux indicates that 30 percent more of the visible wavelength energy and 25 percent more of the near-infrared wavelength energy is absorbed by water offshore of the delta compared to coastal areas with minimal river discharge. The analysis also revealed that the removal of sea ice involves the following: over-ice-flooding along the coast offshore from river delta channels; under-ice flow of 'warm' river water; melting and calving of the fast ice; and, the formation of a bight in the pack ice edge. Two stages in the melting of sea ice were identified: (1) an early stage where heat is supplied to overflows largely by solar radiation, and (2) a later stage where heat is supplied by river discharge in addition to solar radiation. A simple thermodynamic model of the thaw process in the fast ice zone was developed and parameterized based on events recorded by the satellite images. The model treats river discharge as the source of sensible heat at the base of the ice cover. The results of a series of sensitivity tests to assess the influence of river discharge on the near shore ice are presented

    From Tank to Treatment: Modeling Melanoma in Zebrafish

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    Melanoma is the deadliest form of skin cancer and one of few cancers with a growing incidence. A thorough understanding of its pathogenesis is fundamental to developing new strategies to combat mortality and morbidity. Zebrafish-due in large part to their tractable genetics, conserved pathways, and optical properties-have emerged as an excellent system to model melanoma. Zebrafish have been used to study melanoma from a single tumor initiating cell, through metastasis, remission, and finally into relapse. In this review, we examine seminal zebrafish studies that have advanced our understanding of melanoma

    Effective risk governance for environmental policy making: a knowledge management perspective

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    Effective risk management within environmental policy making requires knowledge on natural, economic and social systems to be integrated; knowledge characterised by complexity, uncertainty and ambiguity. We describe a case study in a (UK) central government department exploring how risk governance supports and hinders this challenging integration of knowledge. Forty-five semi-structured interviews were completed over a two year period. We found that lateral knowledge transfer between teams working on different policy areas was widely viewed as a key source of knowledge. However, the process of lateral knowledge transfer was predominantly informal and unsupported by risk governance structures. We argue this made decision quality vulnerable to a loss of knowledge through staff turnover, and time and resource pressures. Our conclusion is that the predominant form of risk governance framework, with its focus on centralised decision-making and vertical knowledge transfer is insufficient to support risk-based, environmental policy making. We discuss how risk governance can better support environmental policy makers through systematic knowledge management practices

    The White/Black Educational Gap, Stalled Progress, and the Long Term Consequences of the Crack Epidemic

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    We propose the rise of crack cocaine as an explanation for the end to the convergence in black-white educational outcomes beginning in the mid-1980s. After constructing a measure of the arrival of crack arrival in cities and states, we first show there are large increases in incarceration and murder rates after the arrival of the drug. We show that the emergence of crack accounts for between 39 and 71 percent of the fall in black male high school graduation rates. The results suggest that, in line with human capital theory, educational investments declined in response to decreased returns to schooling

    Quadrilateral-octagon coordinates for almost normal surfaces

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    Normal and almost normal surfaces are essential tools for algorithmic 3-manifold topology, but to use them requires exponentially slow enumeration algorithms in a high-dimensional vector space. The quadrilateral coordinates of Tollefson alleviate this problem considerably for normal surfaces, by reducing the dimension of this vector space from 7n to 3n (where n is the complexity of the underlying triangulation). Here we develop an analogous theory for octagonal almost normal surfaces, using quadrilateral and octagon coordinates to reduce this dimension from 10n to 6n. As an application, we show that quadrilateral-octagon coordinates can be used exclusively in the streamlined 3-sphere recognition algorithm of Jaco, Rubinstein and Thompson, reducing experimental running times by factors of thousands. We also introduce joint coordinates, a system with only 3n dimensions for octagonal almost normal surfaces that has appealing geometric properties.Comment: 34 pages, 20 figures; v2: Simplified the proof of Theorem 4.5 using cohomology, plus other minor changes; v3: Minor housekeepin

    Broadband X-ray Imaging and Spectroscopy of the Crab Nebula and Pulsar with NuSTAR

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    We present broadband (3 -- 78 keV) NuSTAR X-ray imaging and spectroscopy of the Crab nebula and pulsar. We show that while the phase-averaged and spatially integrated nebula + pulsar spectrum is a power-law in this energy band, spatially resolved spectroscopy of the nebula finds a break at ∼\sim9 keV in the spectral photon index of the torus structure with a steepening characterized by ΔΓ∼0.25\Delta\Gamma\sim0.25. We also confirm a previously reported steepening in the pulsed spectrum, and quantify it with a broken power-law with break energy at ∼\sim12 keV and ΔΓ∼0.27\Delta\Gamma\sim0.27. We present spectral maps of the inner 100\as\ of the remnant and measure the size of the nebula as a function of energy in seven bands. These results find that the rate of shrinkage with energy of the torus size can be fitted by a power-law with an index of γ=0.094±0.018\gamma = 0.094\pm 0.018, consistent with the predictions of Kennel and Coroniti (1984). The change in size is more rapid in the NW direction, coinciding with the counter-jet where we find the index to be a factor of two larger. NuSTAR observed the Crab during the latter part of a γ\gamma-ray flare, but found no increase in flux in the 3 - 78 keV energy band
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