858 research outputs found

    Philadelphia region input-output study working papers. Volume 3 - Final demand

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    Input-output coefficients for 86 final demand sectors in Philadelphia regio

    Exhaustion and Technological Development: a macro-dynamic policy model

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    The main components of the problem complex posed by the Club of Rome are what the joint effect will be, and how it can be influenced, of (i) population growth, (ii) increase of pollution, (iii) the exhaustion of material resources and (iv) technological development. From the discussions of the last few years my main impressions are that policies to curb population growth and pollution are within reach, even though formidable obstacles will have to be faced. Put in oversimplified terms, the population explosion begins to be seen by a rapidly increasing number of people as a danger; various means to put a break on it have been developed and there is a group of countries where the effect of their use begins to be visible. Also a number of expert calculations on the means needed to keep pollution under control suggest that these are of the order of 4 per cent of national income for some developed countries; a figure not too deconcerting. The author is indebted to Professors O. Rademaker and H. Linnemann for helpful comments on an earlier draft of this article. Of course the responsibility for the present text is mine

    A variational assimilation method for satellite and conventional data: development of basic model for diagnosis of cyclone systems

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    In the 1995 ISWS Publications Catalog, the citation for this work is listed as ISWS MP no. 89. A note in the ISWS publications database indicates that ISWS MP 89 was issued as NASA Contractor Report 3981, prepared for George C. Marshall Space Flight Center under Contract NAS8-34902. The ISWS Miscellaneous Publication series statement has been added to the record on the basis of these sources, although there is no reference to the ISWS MP series in the work itself.A summary is presented of the progress toward the completion of a comprehensive diagnostic objective analysis system based upon the calculus of variations. The approach was to first develop the objective analysis subject to the constraints that the final product satisfies the five basic primitive equations for a dry inviscid atmosphere: the two nonlinear horizontal momentum equations, the continuity equation, the hydrostatic equation, and the thermodynamic equation. Then, having derived the basic model, there would be added to it the equations for moist atmospheric processes and the radiative transfer equation.published or submitted for publicationOpe

    Spatial segregation measures: a methodological review

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    Quantitative indices of segregation are powerful tools for summarising the spatial relationships between population groups and thereby providing the basis for analysis and public policy intervention. While the broad concept of segregation may be intuitive, measurement is challenging because of the complexity of varied dimensions and spatial arrangements. Many traditional measures can be criticised for over-simplification or over-reduction, not least in their treatment of geographical space. Over the last several decades, however, a series of measures has been developed to explicitly incorporate the spatial arrangement of population groups as well as their interactions. This paper reviews the development of spatial segregation measures, particularly focusing on the mathematical formulation of spatial arrangement/relations. In addition, several related issues are discussed, including representation of spatial interaction, spatial scale and statistical inferences. Also, this paper presents an overview of existing software tools that are readily available for calculating some of the reviewed measures. Finally, discussions on challenges and future research are provided

    Non-overlapping Distributed Tracking System Utilizing Particle Filter

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    Tracking people across multiple cameras is a challenging research area in visual computing, especially when these cameras have non-overlapping field of views. The important task is to associate a current subject with other prior appearances of the same subject across time and space in a camera network. Several known techniques rely on Bayesian approaches to perform the matching task. However, these approaches do not scale well when the dimension of the problem increases; e.g. when the number of subject or possible path increases. The aim of this paper is to propose a unified tracking framework using particle filters to efficiently switch between visual tracking (field of view tracking) and track prediction (non-overlapping region tracking). The particle filter tracking system utilizes a map (known environment) to assist the tracking process when targets leave the field of view of any camera. We implemented and tested this tracking approach in an in-house multiple cameras system as well as using on-line data. Promising results were obtained which suggested the feasibility of such an approach

    Entry, Growth, and Survival in the Green Industry

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    Economists are interested in the factors that induce firm entry, lead to growth, and help firms succeed in various markets. Such information can be helpful to policymakers but, unfortunately, such patterns have not been considered for “green industries.” This paper takes advantage of a recent definition of green industries proposed by the Bureau of Labor Statistics to investigate patterns characterizing these industries within the State of Texas. Leveraging the differences between the five sub-categories within the BLS definition, this study attempts to identify the comparative advantage each county has within the green economy

    From Select Agent to an Established Pathogen: The Response to \u3ci\u3ePhakopsora pachyrhizi\u3c/i\u3e (Soybean Rust) in North America

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    The pathogen causing soybean rust, Phakopsora pachyrhizi, was first described in Japan in 1902. The disease was important in the Eastern Hemisphere for many decades before the fungus was reported in Hawaii in 1994, which was followed by reports from countries in Africa and South America. In 2004, P. pachyrhizi was confirmed in Louisiana, making it the first report in the continental United States. Based on yield losses from countries in Asia, Africa, and South America, it was clear that this pathogen could have a major economic impact on the yield of 30 million ha of soybean in the United States. The response by agencies within the United States Department of Agriculture, industry, soybean check-off boards, and universities was immediate and complex. The impacts of some of these activities are detailed in this review. The net result has been that the once dreaded disease, which caused substantial losses in other parts of the world, is now better understood and effectively managed in the United States. The disease continues to be monitored yearly for changes in spatial and temporal distribution so that soybean growers can continue to benefit by knowing where soybean rust is occurring during the growing season

    Ventral-aspect radar cross sections and polarization patterns of insects at X band and their relation to size and form

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    A data set of ventral-aspect insect radar cross-sections (RCSs) and polarization patterns, measured at X band (9.4 GHz, linear polarization) in laboratory rigs, has been collated from a number of sources. The data have been analysed to identify relationships between RCS parameters (one representing size and two the polarization-pattern shape) and the insects’ masses and morphological dimensions and forms. An improved mass-estimation relationship, with appropriate asymptotes for very small and very large insects, is presented. This relationship draws only on the RCS size parameter and it is shown that incorporating one or both of the RCS shape parameters provides little additional benefit. Small insects have polarization-pattern shapes that fall within a relatively limited region of the range of parameter values allowed by electromagnetic scattering theory. Larger insects have shapes that extend beyond this region, following a broad trajectory as size and mass increases; at masses above ~0.6 g, the pattern becomes ‘perpendicular’, with maxima when the E-field is orthogonal to the body axis rather than parallel to it. RCS shape can be used to infer morphological form for small insects (<80 mg), but not for larger ones. These results are consistent with observations from X-band vertical-beam entomological radars and provide a basis for identification, at least to broad taxon classes, of the targets detected by such radars

    Hopping Transport in the Presence of Site Energy Disorder: Temperature and Concentration Scaling of Conductivity Spectra

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    Recent measurements on ion conducting glasses have revealed that conductivity spectra for various temperatures and ionic concentrations can be superimposed onto a common master curve by an appropriate rescaling of the conductivity and frequency. In order to understand the origin of the observed scaling behavior, we investigate by Monte Carlo simulations the diffusion of particles in a lattice with site energy disorder for a wide range of both temperatures and concentrations. While the model can account for the changes in ionic activation energies upon changing the concentration, it in general yields conductivity spectra that exhibit no scaling behavior. However, for typical concentrations and sufficiently low temperatures, a fairly good data collapse is obtained analogous to that found in experiment.Comment: 6 pages, 4 figure
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