182 Matching Results

Search Results

Advanced search parameters have been applied.

Internal Migration in the United States: Its Components and Trends

Description: This report discusses of internal migration trends in the U.S. such as the migration of people from rural areas to cities and the growth of suburbs along with associated economic consequences, social struggles, and possible solutions to alleviate some of these problems. Three groups migrations are specifically discussed (Dust Bowl farmers becoming transient workers in the 1930s, Appalachian families moving out of the mountains in the 1940s-1960s, and southern African-Americans moving to the north especially to urban areas in the 1950s-1960s).
Date: February 5, 1971
Creator: Mitrisin, John D.
Partner: UNT Libraries Government Documents Department

Upper Limits on the Number of Small Bodies in Sedna-Like Orbits by the TAOS Project

Description: We present the results of a search for occultation events by objects at distances between 100 and 1000 AU in lightcurves from the Taiwanese-American Occultation Survey (TAOS). We searched for consecutive, shallow flux reductions in the stellar lightcurves obtained by our survey between 7 February 2005 and 31 December 2006 with a total of {approx} 4.5 x 10{sup 9} three-telescope simultaneous photometric measurements. No events were detected, allowing us to set upper limits on the number density as a function of size and distance of objects in Sedna-like orbits, using simple models.
Date: November 13, 2009
Creator: Wang, J; Lehner, M J; Zhang, Z; Bianco, F B; Alcock, C; Chen, W et al.
Partner: UNT Libraries Government Documents Department

Debuncher Momentum Aperture Measurements

Description: During the November 1990 through January 1991 {bar p} studies period, the momentum aperture of the beam in the debuncher ring was measured. The momentum aperture ({Delta}p/p) was found to be 4.7%. The momentum spread was also measured with beam bunch rotation off. A nearly constant particle population density was observed for particles with {Delta}p/p of less than 4.3%, indicating virtually unobstructed orbits in this region. The population of particles with momenta outside this aperture was found to decrease rapidly. An absolute or 'cut-off' momentum aperture of {Delta}p/p = 5.50% was measured.
Date: January 1, 1991
Creator: O'Day, S.
Partner: UNT Libraries Government Documents Department

Implementation of a new algorithm for Density Equalizing Map Projections (DEMP)

Description: The purpose of the PAREP (Populations at Risk to Environmental Pollution) Project at Lawrence Berkeley National Laboratory (LBNL), an ongoing Department of Energy (DOE) project since 1978, is to develop resources (data, computing techniques, and biostatistical methodology) applicable to DOE`s needs. Specifically, the PAREP project has developed techniques for statistically analyzing disease distributions in the vicinity of supposed environmental hazards. Such techniques can be applied to assess the health risks in populations residing near DOE installations, provided adequate small-area health data are available. The FY 1994 task descriptions for the PAREP project were determined in discussions at LBNL on 11/2/93. The FY94 PAREP Work Authorization specified three major tasks: a prototype small area study, a feasibility study for obtaining small-area data, and preservation of the PAREP data archive. The complete FY94 work plan, and the subtasks accomplished to date, were included in the Cumulative FY94 progress report.
Date: July 1, 1995
Creator: Close, E.R.; Merrill, D.W. & Holmes, H.H.
Partner: UNT Libraries Government Documents Department

Geographical Distribution of Biomass Carbon in Tropical Southeast Asian Forests: A Database

Description: A database was generated of estimates of geographically referenced carbon densities of forest vegetation in tropical Southeast Asia for 1980. A geographic information system (GIS) was used to incorporate spatial databases of climatic, edaphic, and geomorphological indices and vegetation to estimate potential (i.e., in the absence of human intervention and natural disturbance) carbon densities of forests. The resulting map was then modified to estimate actual 1980 carbon density as a function of population density and climatic zone. The database covers the following 13 countries: Bangladesh, Brunei, Cambodia (Campuchea), India, Indonesia, Laos, Malaysia, Myanmar (Burma), Nepal, the Philippines, Sri Lanka, Thailand, and Vietnam. The data sets within this database are provided in three file formats: ARC/INFO{trademark} exported integer grids, ASCII (American Standard Code for Information Interchange) files formatted for raster-based GIS software packages, and generic ASCII files with x, y coordinates for use with non-GIS software packages. This database includes ten ARC/INFO exported integer grid files (five with the pixel size 3.75 km x 3.75 km and five with the pixel size 0.25 degree longitude x 0.25 degree latitude) and 27 ASCII files. The first ASCII file contains the documentation associated with this database. Twenty-four of the ASCII files were generated by means of the ARC/INFO GRIDASCII command and can be used by most raster-based GIS software packages. The 24 files can be subdivided into two groups of 12 files each. These files contain real data values representing actual carbon and potential carbon density in Mg C/ha (1 megagram = 10{sup 6} grams) and integer- coded values for country name, Weck's Climatic Index, ecofloristic zone, elevation, forest or non-forest designation, population density, mean annual precipitation, slope, soil texture, and vegetation classification. One set of 12 files contains these data at a spatial resolution of 3.75 km, whereas the other set of ...
Date: February 7, 2002
Creator: Brown, S.
Partner: UNT Libraries Government Documents Department

Plasma in Saturn's nightside magnetosphere and the implications for global circulation

Description: We present a bulk ion flow map from the nightside equatorial region of Saturn's magnetosphere derived from the Cassini CAPS ion mass spectrometer data. The map clearly demonstrates the dominance of corotation flow over radial flow and suggests that the flux tubes sampled are still closed and attached to the planet up to distances of 50 R{sub s}. The plasma characteristics in the near-midnight region are described and indicate a transition between the region of the magnetosphere containing plasma on closed drift paths and that containing flux tubes which may not complete a full rotation around the planet. Data from the electron spectrometer reveal two plasma states of high and low density. These are attributed either to the sampling of mass-loaded and depleted flux tubes, respectively, or to the latitudinal structure of the plasma sheet Depleted, returning flux tubes are not, in general, directly observed in the ions, although the electron observations suggest that such a process must take place in order to produce the low density population. Flux tube content is conserved below a limIt defined by the mass-loading and magnetic field strength and indicates that the flux tubes sampled may survive their passage through the tail. The conditions for mass release are evaluated using measured densities, angular velocities and magnetic field strength, The results suggest that for the relatively dense ion populations detectable by IMS, the condition for flux-tube breakage has not yet been exceeded, However, the low-density regimes observed in the electron data suggest that loaded flux tubes at greater distances do exceed the threshold for mass loss and subsequently return to the inner magnetosphere significantly depleted of plasma.
Date: January 1, 2009
Creator: Mcandrews, Hazel J; Wilson, R J; Henderson, M G; Tokar, R L; Jackman, C M; Khurana, K K et al.
Partner: UNT Libraries Government Documents Department

Some Implications of Population Growth on the Economic Development of Nigeria: 1952-1982

Description: This is a demographic study of Nigeria between 1952-1982. Relationships between population growth and economic development are described in detail. Comparisons are made of demographic growth in Nigeria with other developing countries, particularly those in Africa. Population pressure, the condition of the rural areas, and some internal and external population problems are discussed in length. The government's position and the public view on population control and family planning programs are also examined. Current programs of family limitation are discussed and evaluated. The study concludes with recommendations for solutions. Emphasis is placed on the need for immediate recognition and action. Various solutions, particularly education, are evaluated.
Date: August 1984
Creator: Oparanozie, Nnamdi Pat
Partner: UNT Libraries

MACHO RR lyrae in the inner halo and bulge

Description: The RR Lyrse in the bulge have been proposed to be the oldest populations in the Milky Way, tracers of how the galaxy formed. We study here the distribution of ?{approximately}1600 bulge RR Lyrae stars found by the MACHO Project. The RR Lyrae with 0.4 ? R ? 3 kpc show a density law that is well fit by the extension of the metal-poor stellar halo present in the outer regions of the Milky Way.
Date: October 1, 1998
Creator: Drake, A.; Alcock, C.; Allsman, R. A.; Alves, D. R.; Axelrod, T.S.; Becker, A. et al.
Partner: UNT Libraries Government Documents Department

A comprehensive landscape approach for monitoring bats on the Nevada Test Site in south-central Nevada

Description: The Nevada Test Site (NTS) is located in south-central Nevada and encompasses approximately 3,497 square kilometers (1,350 square miles). It straddles both the Mojave and Great Basin Deserts and includes a distinct transition region between these two deserts. Because of its geographical location, a great level of vegetative and physiographic diversity exists on the NTS. Also, numerous mines and tunnels are found on the NTS which are potential roost sites for bats. Multiple technqiues are being used to inventory and monitor the bat fauna on the NTS. These techniques include mistnetting at water sources with concurrent use of the Anabat II bat detection system, conducting road surveys with the Anabat II system, and conducting exit surveys at mine and tunnel entrances using the Anabat II system. To date, a total of 13 species of bats has been documented on the NTS, of which six are considered species of concern by the US Fish and Wildlife Service. These include Townsend's big-eared bat (Corynorhinus townsendii), spotted bat (Euderma maculatum), small-footed myotis (Myotis ciliolabrum), long-eared myotis (M. evotis), fringed myotis (M. thysanodes), and long-legged myotis (M. volans). Results from mistnet and Anabat surveys reveal that all bat species of concern except for the long-legged myotis are found exclusively in the Great Basin Desert portion of the NTS. The long-legged myotis is found throughout the NTS. The Anabat II system has greatly facilitated the monitoring of bats on the NTS, and allowed biologists to cost effectively survey large areas for bat activity. Information obtained from bat monitoring will be used to develop and update guidelines for managing bats on the NTS.
Date: January 1, 2000
Creator: Hall, D.
Partner: UNT Libraries Government Documents Department

Distribution of the Chuckwalla, Western Burrowing Owl, and Six Bat Species on the Nevada Test Site

Description: Field Surveys were conducted in 1996 to determine the current distribution of several animal species of concern on the Nevada Test Site (NTS). They included the chuckwall (Sauromalus obesus), western burrowing owl (Speotyto cunicularia), and six species of bats. Nineteen chuckwallas and 118 scat locations were found during the chuckwalla field study. Eighteen western burrowing owls were found at 12 sighting locations during the 1996 field study. Of the eleven bat species of concern which might occur on the NTS, five, and possibly six, were captured during this survey. The U.S. Department of Energy, Nevada Operations Office, takes certain management actions to protect and conserve the chuckwalla, western burrowing owl, and bats on the NTS. These actions are described and include: (1) conducting surveys at sites of proposed land-disturbing activities (2) altering projects whenever possible to avoid or minimize impacts to these species (3) maintaining a geospatial database of known habitat for species of concern (4) sharing sighting and trap location data gathered on the NTS with other local land and resource managers, and (5) conducting periodic field surveys to monitor these species distribution and relative abundance on the NTS.
Date: May 1, 1997
Creator: Willis, Cathy A.
Partner: UNT Libraries Government Documents Department

Congestion on Multilane Highways

Description: We present a new model for traffic on a multilane freeway (with n lanes). Our basic descriptors are the car density {rho} (in cars/mile) taken across all lanes in the freeway and the average car velocity u (in miles/hour). In this paper we present a model which incorporates both equilibrium curves and a simple switching mechanism which allows cars to transit from one equilibrium curve to the other. This switching mechanism, when combined with the continuity equation, produces relaxation or self-excited oscillations in the system and these oscillations are what interests us here.
Date: July 1, 2002
Creator: Greenberg, J.M.; Klar, A. & Rascle, M.
Partner: UNT Libraries Government Documents Department

Inhalation of primary motor vehicle emissions: Effects of urbanpopulation and land area

Description: Urban population density can influence transportation demand, as expressed through average daily vehicle-kilometers traveled per capita (VKT). In turn, changes in transportation demand influence total passenger vehicle emissions. Population density can also influence the fraction of total emissions that are inhaled by the exposed urban population. Equations are presented that describe these relationships for an idealized representation of an urban area. Using analytic solutions to these equations, we investigate the effect of three changes in urban population and urban land area (infill, sprawl, and constant-density growth) on per capita inhalation intake of primary pollutants from passenger vehicles. The magnitude of these effects depends on density-emissions elasticity ({var_epsilon}{sub e}), a normalized derivative relating change in population density to change in vehicle emissions. For example, if urban population increases, per capita intake is less with infill development than with constant-density growth if {var_epsilon}{sub e} is less than -0.5, while for {var_epsilon}{sub e} greater than -0.5 the reverse is true.
Date: June 14, 2004
Creator: Marshall, Julian D.; McKone, Thomas E. & Nazaroff, William W.
Partner: UNT Libraries Government Documents Department

The effect of area size and predation on the time to extinction of prairie vole populations. simulation studies via SERDYCA: a Spatially-Explicit Individual-Based Model of Rodent Dynamics

Description: We present a spatially-explicit individual-based computational model of rodent dynamics, customized for the prairie vole species, M. Ochrogaster. The model is based on trophic relationships and represents important features such as territorial competition, mating behavior, density-dependent predation and dispersal out of the modeled spatial region. Vegetation growth and vole fecundity are dependent on climatic components. The results of simulations show that the model correctly predicts the overall temporal dynamics of the population density. Time-series analysis shows a very good match between the periods corresponding to the peak population density frequencies predicted by the model and the ones reported in the literature. The model is used to study the relation between persistence, landscape area and predation. We introduce the notions of average time to extinction (ATE) and persistence frequency to quantify persistence. While the ATE decreases with decrease of area, it is a bell-shaped function of the predation level: increasing for 'small' and decreasing for 'large' predation levels.
Date: November 21, 2003
Creator: Kostova, T & Carlsen, T
Partner: UNT Libraries Government Documents Department

New York Household Travel Patterns: A Comparison Analysis

Description: In 1969, the U. S. Department of Transportation began collecting detailed data on personal travel to address various transportation planning issues. These issues range from assessing transportation investment programs to developing new technologies to alleviate congestion. This 1969 survey was the birth of the Nationwide Personal Transportation Survey (NPTS). The survey was conducted again in 1977, 1983, 1990 and 1995. Longer-distance travel was collected in 1977 and 1995. In 2001, the survey was renamed to the National Household Travel Survey (NHTS) and collected both daily and longer-distance trips in one survey. In addition to the number of sample households that the national NPTS/NHTS survey allotted to New York State (NYS), the state procured an additional sample of households in both the 1995 and 2001 surveys. In the 1995 survey, NYS procured an addition sample of more than 9,000 households, increasing the final NY NPTS sample size to a total of 11,004 households. Again in 2001, NYS procured 12,000 additional sample households, increasing the final New York NHTS sample size to a total of 13,423 households with usable data. These additional sample households allowed NYS to address transportation planning issues pertinent to geographic areas significantly smaller than for what the national NPTS and NHTS data are intended. Specifically, these larger sample sizes enable detailed analysis of twelve individual Metropolitan Planning Organizations (MPOs). Furthermore, they allowed NYS to address trends in travel behavior over time. In this report, travel data for the entire NYS were compared to those of the rest of the country with respect to personal travel behavior and key travel determinants. The influence of New York City (NYC) data on the comparisons of the state of New York to the rest of the country was also examined. Moreover, the analysis examined the relationship between population density and travel patterns, ...
Date: May 1, 2007
Creator: Hu, Patricia S & Reuscher, Tim
Partner: UNT Libraries Government Documents Department

Nevada Test Site Environmental Report 2005, Attachment A - Site Description

Description: This appendix to the ''Nevada Test Site Environmental Report 2005'', dated October 2006 (DOE/NV/11718--1214; DOE/NV/25946--007) expands on the general description of the Nevada Test Site (NTS) presented in the Introduction. Included are subsections that summarize the site?s geological, hydrological, climatological, and ecological setting. The cultural resources of the NTS are also presented. The subsections are meant to aid the reader in understanding the complex physical and biological environment of the NTS. An adequate knowledge of the site's environment is necessary to assess the environmental impacts of new projects, design and implement environmental monitoring activities for current site operations, and assess the impacts of site operations on the public residing in the vicinity of the NTS. The NTS environment contributes to several key features of the site which afford protection to the inhabitants of adjacent areas from potential exposure to radioactivity or other contaminants resulting from NTS operations. These key features include the general remote location of the NTS, restricted access, extended wind transport times, the great depths to slow-moving groundwater, little or no surface water, and low population density. This appendix complements the annual summary of monitoring program activities and dose assessments presented in the main body of this report.
Date: October 1, 2006
Creator: Wills, Cathy A.
Partner: UNT Libraries Government Documents Department

Nevada Test Site Environmental Report 2008 Attachment A: Site Description

Description: This attachment expands on the general description of the Nevada Test Site (NTS) presented in the Introduction to the Nevada Test Site Environmental Report 2008 (National Security Technologies, LLC [NSTec], 2009a). Included are subsections that summarize the site’s geological, hydrological, climatological, and ecological setting. The cultural resources of the NTS are also presented. The subsections are meant to aid the reader in understanding the complex physical and biological environment of the NTS. An adequate knowledge of the site’s environment is necessary to assess the environmental impacts of new projects, design and implement environmental monitoring activities for current site operations, and assess the impacts of site operations on the public residing in the vicinity of the NTS. The NTS environment contributes to several key features of the site that afford protection to the inhabitants of adjacent areas from potential exposure to radioactivity or other contaminants resulting from NTS operations. These key features include the general remote location of the NTS, restricted access, extended wind transport times, the great depths to slow-moving groundwater, little or no surface water, and low population density. This attachment complements the annual summary of monitoring program activities and dose assessments presented in the main body of this report.
Date: September 1, 2009
Creator: Wills, Cathy A.
Partner: UNT Libraries Government Documents Department

Lawrence Livermore National Laboratory Emergency Response Capability Baseline Needs Assessment Requirement Document

Description: This revision of the LLNL Fire Protection Baseline Needs Assessment (BNA) was prepared by John A. Sharry, LLNL Fire Marshal and LLNL Division Leader for Fire Protection and reviewed by Martin Gresho, Sandia/CA Fire Marshal. The document follows and expands upon the format and contents of the DOE Model Fire Protection Baseline Capabilities Assessment document contained on the DOE Fire Protection Web Site, but only address emergency response. The original LLNL BNA was created on April 23, 1997 as a means of collecting all requirements concerning emergency response capabilities at LLNL (including response to emergencies at Sandia/CA) into one BNA document. The original BNA documented the basis for emergency response, emergency personnel staffing, and emergency response equipment over the years. The BNA has been updated and reissued five times since in 1998, 1999, 2000, 2002, and 2004. A significant format change was performed in the 2004 update of the BNA in that it was 'zero based.' Starting with the requirement documents, the 2004 BNA evaluated the requirements, and determined minimum needs without regard to previous evaluations. This 2010 update maintains the same basic format and requirements as the 2004 BNA. In this 2010 BNA, as in the previous BNA, the document has been intentionally divided into two separate documents - the needs assessment (1) and the compliance assessment (2). The needs assessment will be referred to as the BNA and the compliance assessment will be referred to as the BNA Compliance Assessment. The primary driver for separation is that the needs assessment identifies the detailed applicable regulations (primarily NFPA Standards) for emergency response capabilities based on the hazards present at LLNL and Sandia/CA and the geographical location of the facilities. The needs assessment also identifies areas where the modification of the requirements in the applicable NFPA standards is appropriate, due ...
Date: December 30, 2009
Creator: Sharry, J A
Partner: UNT Libraries Government Documents Department

Impacts to Dungeness Crab from the Southwest Washington Littoral Drift Restoration Project

Description: The Benson Beach littoral drift restoration project is a demonstration project that will replenish sand on Benson Beach, the public beach north of the North Jetty at the mouth of the Columbia River (MCR), using material dredged from the river during normal maintenance dredging of the navigational channel. A U.S. Army Corps of Engineers (Corps) proposal involves pumping the material from a sump area on the south side of the jetty to Benson Beach using a cutter suction dredge, also known as a pipeline dredge. If this one-time demonstration project proves feasible and successful, up to a million cubic yards of sediment could be used to replenish the outer coast littoral drift system in successive years by the same process. The primary goal of this study was to assess the potential risk of impacts to Dungeness crab from the proposed Benson Beach littoral drift restoration process of using the cutter suction dredge to move sediment from the proposed sump area on one side of the North Jetty to the beach on the other side of the jetty. Because there are no direct measurements of crab entrainment by pipeline dredge operating outside of the lower Columbia River navigation channel, dredge impacts for the proposed demonstration project were estimated using a modification of the dredge impact model (DIM) of Armstrong et al. (1987). The model estimates adult equivalent loss (AEL) of crabs using crab population density from trawl surveys, dredge project information (gear type, season, location, volume), and an entrainment function relating crab population density to entrainment by the dredge. The input used in applying the DIM to the Benson Beach littoral drift restoration included the specific dredging scenario provided by the Corps, existing data on crab density in previously proposed sump areas, and a series of entrainment functions. A total of ...
Date: November 9, 2005
Creator: Williams, Greg D.; Kohn, Nancy P.; Pearson, Walter H. & Skalski, J R.
Partner: UNT Libraries Government Documents Department

The 2006 Project Progress Report for 1987-099-00 Dworshak Kokanee Population and Entrainment Assessment (contract # 26850) is attached to project 2007-003-00, contract #31598. [POINTER]

Description: During this contract, we continued testing underwater strobe lights to determine their effectiveness at repelling kokanee Oncorhynchus nerka away from Dworshak Dam. Strobe light tests were conducted on four nights from April 24-27, 2006, in front of the middle reservoir outlet (RO) 2. The density and distribution of fish, (thought to be mostly kokanee), were monitored with a split-beam echo sounder. We then compared fish counts and densities during nights when the lights were flashing to counts and densities during adjacent nights without the lights on. On two nights, April 25 and 27, 2006, when no lights were present, fish counts near RO 2 averaged 12.4 fish and densities averaged 31.0 fish/ha. When strobe lights were turned on during the nights of April 24 and 26, mean counts dropped to 4.7 fish and densities dropped to 0.5 fish/ha. The decline in counts (62%) and densities (99%) was statistically significant (p = 0.009 and 0.002, respectively). Test results indicated that strobe lights were able to reduce fish densities by at least 50% in front of a discharging reservoir outlet, which would be sufficient to improve sport fish harvest. We also used split-beam hydroacoustics to monitor the kokanee population in Dworshak Reservoir during 2006. Estimated abundance of kokanee increased from the 2005 population estimate. Based on hydroacoustic surveys, we estimated approximately 5,815,000 kokanee (90% CI {+-} 27.6%) in Dworshak Reservoir in August 2006. This included 2,183,000 age-0 (90% CI {+-} 24.2%), 1,509,000 age-1 (90% CI {+-} 29.0%), and 2,124,000 age-2 (90% CI {+-} 27.6%) kokanee. This resulted in a density of age-2 kokanee above the management goal of 30-50 adults/ha. Entrainment sampling was conducted with fixed-site, split-beam hydroacoustics from May through September for a continuous 24 h period when dam operations permitted. The highest fish detection rates from entrainment assessments were found ...
Date: December 18, 2008
Partner: UNT Libraries Government Documents Department

Secondary succession: Composition of the vegetation and primary production in the field-to-forest at Brookhaven, Long Island, N.Y.

Description: Natural communities respond to disruption through a series of changes in plant and animal communities that are broadly predictable. The field-to-forest sere of central Long Island follows the pattern set forth earlier for the Piedmont of North Carolina and for New Jersey. The communities of herbs that occur in the years immediately after abandonment are followed by an Andropogon stage which is replaced before the 20th year by pine forest. The pine is replaced in the next 25 years by oak-pine, which in the normal Course is followed by oak-hickory. With repeated burning the oak-pine stage in various combinations of oaks and pine may be maintained indefinitely. Diversity, measured as number of species per unit land area, increased in this sere through the 3-5th years after abandonment to a maximum, dropped, and rose again in the later forest stages. Exotics were a conspicuous part of the communities of the earlier stages but their importance diminished as succession progressed and their contribution to net production was zero beyond the 20th year. The removal of exotics would probably not have changed the pattern of diversity appreciably. Net primary production increased with succession in this sere with major changes occurring as life-forms of the dominants shifted to woody plants. The peak net production was in the most mature forest, about 1200 g/m{sup 2}/yr. Root/shoot ratios declined from 4-5 in the early stages of succession to 0.3-0.5 with later stages. The standing crop of organic matter including humus throughout the sere was about 15 times the net production, indicating a halftime of residence for all organic matter throughout the sere of about 10 years.
Date: August 23, 1973
Creator: Woodwell,G.M.; Holt, B. R. & Flaccus, E.
Partner: UNT Libraries Government Documents Department

Four new BL Lac surveys: sampling new populations

Description: The advent of large area deep radio and X-ray surveys is leading to the creation of many new BLLac samples. In particular, the ROSAT All-Sky, Green Bank and FIRST surveys are proving to be rich sources of new BLLacs. We will discuss the methods used in four in-dependent BLLac searches based on these surveys. Comparison of the broadband spectral energy distributions of these BLLac with those of previously known objects clearly points to the existence of a large previously unrecognized population of objects with characteristics intermediate between those exhibited by Low and High energy peaked BLLacs.
Date: June 1, 1998
Creator: Schmidt, G.; Becker, R. H.; Brinkmann, W.; Feigelson, E. D.; Kollgaard, R. I.; Laurent-Muehleisen, S. et al.
Partner: UNT Libraries Government Documents Department

Density equalizing map projections (cartograms) in public health applications

Description: In studying geographic disease distributions, one normally compares rates among arbitrarily defined geographic subareas (e.g. census tracts), thereby sacrificing some of the geographic detail of the original data. The sparser the data, the larger the subareas must be in order to calculate stable rates. This dilemma is avoided with the technique of Density Equalizing Map Projections (DEMP){copyright}. Boundaries of geographic subregions are adjusted to equalize population density over the entire study area. Case locations plotted on the transformed map should have a uniform distribution if the underlying disease risk is constant. On the transformed map, the statistical analysis of the observed distribution is greatly simplified. Even for sparse distributions, the statistical significance of a supposed disease cluster can be calculated with validity. The DEMP algorithm was applied to a data set previously analyzed with conventional techniques; namely, 401 childhood cancer cases in four counties of California. The distribution of cases on the transformed map was analyzed visually and statistically. To check the validity of the method, the identical analysis was performed on 401 artificial cases randomly generated under the assumption of uniform risk. No statistically significant evidence for geographic non-uniformity of rates was found, in agreement with the original analysis performed by the California Department of Health Services.
Date: May 1, 1998
Creator: Merrill, D.W.
Partner: UNT Libraries Government Documents Department

SECPOP90: Sector population, land fraction, and economic estimation program

Description: In 1973 Mr. W. Athey of the Environmental Protection Agency wrote a computer program called SECPOP which calculated population estimates. Since that time, two things have changed which suggested the need for updating the original program - more recent population censuses and the widespread use of personal computers (PCs). The revised computer program uses the 1990 and 1992 Population Census information and runs on current PCs as {open_quotes}SECPOP90.{close_quotes} SECPOP90 consists of two parts: site and regional. The site provides population and economic data estimates for any location within the continental United States. Siting analysis is relatively fast running. The regional portion assesses site availability for different siting policy decisions; i.e., the impact of available sites given specific population density criteria within the continental United States. Regional analysis is slow. This report compares the SECPOP90 population estimates and the nuclear power reactor licensee-provided information. Although the source, and therefore the accuracy, of the licensee information is unknown, this comparison suggests SECPOP90 makes reasonable estimates. Given the total uncertainty in any current calculation of severe accidents, including the potential offsite consequences, the uncertainty within SECPOP90 population estimates is expected to be insignificant. 12 refs., 55 figs., 7 tabs.
Date: September 1997
Creator: Humphreys, S. L.; Rollstin, J. A. & Ridgely, J. N.
Partner: UNT Libraries Government Documents Department

Environmental Justice Assessment for Transportation

Description: Application of Executive Order 12898 to risk assessment of highway or rail transport of hazardous materials has proven difficult; the location and conditions affecting the propagation of a plume of hazardous material released in a potential accident are unknown, in general. Therefore, analyses have only been possible in geographically broad or approximate manner. The advent of geographic information systems and development of software enhancements at Sandia National Laboratories have made kilometer-by-kilometer analysis of populations tallied by U.S. Census Blocks along entire routes practicable. Tabulations of total, or racially/ethnically distinct, populations close to a route, its alternatives, or the broader surrounding area, can then be compared and differences evaluated statistically. This paper presents methods of comparing populations and their racial/ethnic compositions using simple tabulations, histograms and Chi Squared tests for statistical significance of differences found. Two examples of these methods are presented: comparison of two routes and comparison of a route with its surroundings.
Date: April 5, 1999
Creator: Mills, G.S. & Neuhauser, K.S.
Partner: UNT Libraries Government Documents Department