Science.gov

Sample records for meeting atlanta ga

  1. 75 FR 2582 - Proposed Modification of the Atlanta, GA, Class B Airspace Area; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-15

    ... Friday, December 4, 2009, concerning a proposal to revise Class B airspace at Atlanta, GA, (74 FR 63818... a proposal to revise Class B airspace at Atlanta, GA, (74 FR 63818). The address and phone number..., in Covington, GA, as published in the Federal Register on Friday, December 4, 2009 (74 FR 63818),...

  2. 75 FR 41884 - Notice of Inventory Completion: Georgia Department of Transportation, Atlanta, GA; University of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-19

    ... National Park Service Notice of Inventory Completion: Georgia Department of Transportation, Atlanta, GA... and associated funerary objects in the control of the Georgia Department of Transportation, Atlanta... Environmental Services-16th Floor, One Georgia Center, 600 West Peachtree St. NW, Atlanta, GA 30308,...

  3. 77 FR 8255 - Constitution Road Drum Superfund Site, Atlanta, Dekalb County, GA; Notice of Settlement

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-14

    ... AGENCY Constitution Road Drum Superfund Site, Atlanta, Dekalb County, GA; Notice of Settlement AGENCY: Environmental Protection Agency. ACTION: Notice of Settlement. SUMMARY: Under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), the United States Environmental Protection Agency...

  4. 77 FR 2981 - Constitution Road Drum Superfund Site; Atlanta, Dekalb County, GA; Notice of Settlement

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-20

    ... AGENCY Constitution Road Drum Superfund Site; Atlanta, Dekalb County, GA; Notice of Settlement AGENCY: Environmental Protection Agency. ACTION: Notice of settlement. SUMMARY: Under Section 122(h)(1) of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), the United States...

  5. 76 FR 45771 - Foreign-Trade Zone 26-Atlanta, GA; Application for Manufacturing Authority; Makita Corporation of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-01

    ... Foreign-Trade Zones Board Foreign-Trade Zone 26--Atlanta, GA; Application for Manufacturing Authority... Manufacturing); Buford, GA An application has been submitted to the Foreign-Trade Zones Board (the Board) by Georgia Foreign-Trade Zone, Inc., grantee of FTZ 26, requesting manufacturing authority on behalf...

  6. 77 FR 75406 - Foreign-Trade Zone 26-Atlanta, GA; Notification of Proposed Production Activity; Perkins Shibaura...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-20

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE Foreign-Trade Zones Board Foreign-Trade Zone 26--Atlanta, GA; Notification of Proposed Production Activity; Perkins Shibaura Engines LLC, (Diesel Engines), Griffin, GA Perkins Shibaura Engines LLC (Perkins Shibaura), an operator of FTZ 26, submitted...

  7. 77 FR 52310 - Foreign-Trade Zone 26-Atlanta, GA, Application for Reorganization (Expansion of Service Area...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-29

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE Foreign-Trade Zones Board Foreign-Trade Zone 26--Atlanta, GA, Application for Reorganization (Expansion of Service Area), Under the Alternative Site Framework, Amendment of Application A request has been...

  8. Summary of Needs and Opportunities from the 2011 Residential Energy Efficiency Stakeholders Meeting: Atlanta, Georgia -- March 16-18, 2011

    SciTech Connect

    Not Available

    2011-05-01

    This summary report outlines needs and issues for increasing energy efficiency of new and existing U.S homes, as identified at the U.S Department of Energy Building America program Spring 2011 stakeholder meeting in Atlanta, Georgia.

  9. International Year of Astronomy (IYA): A Boost to Astronomy Education in Atlanta, GA

    NASA Astrophysics Data System (ADS)

    Sarrazine, Angela R.; Albin, E.

    2010-01-01

    We report on the International Year of Astronomy (IYA) activities at Fernbank Science Center in Atlanta, GA (USA). The global focus of IYA was to celebrate astronomy and its cultural / scientific contributions, which correlate with the 400th anniversary of Galileo's first look at the heavens with a small telescope. Our planetarium and observatory utilized this opportunity to increase astronomy awareness and education locally. A plethora of special events were organized including two planetarium productions about Galileo and the telescope, special displays in the exhibit hall, two astronaut lectures, a children's workshop with Galileoscopes, and even a Galileo impersonator. Such IYA-related programs increased our overall annual attendance while at the same time served to re-introduce our local audience to astronomy in a creative way.

  10. Destination Station Atlanta

    NASA Video Gallery

    Destination Station was recently in Atlanta from April 15 through April 21. During the week, NASA visited schools, hospitals, museums, and the city’s well known Atlanta Science Tavern Meet Up gro...

  11. 75 FR 62323 - Approval and Promulgation of Air Quality Implementation Plans; Atlanta, GA; Notice of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-08

    ... area (hereafter referred to as the ``Atlanta Area''). Pursuant to the Clean Air Act (CAA) and its... as ``nonattainment area submittals'') submitted by the State of Georgia for the Atlanta Area. On... PM 2.5 nonattainment submittals for the Atlanta Area. Today's notice is simply an announcement of...

  12. Photocopy of photograph (original photograph in possession of Atlanta Housing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photocopy of photograph (original photograph in possession of Atlanta Housing Authority, Atlanta GA). Photographer unknown, circa 1940. VIEW OF APARTMENT INTERIOR. - Techwood Homes (Public Housing), Bounded by North Avenue, Parker Street, William Street & Lovejoy Street, Atlanta, Fulton County, GA

  13. Characterization of CCN and IN activity of bacterial isolates collected in Atlanta, GA

    NASA Astrophysics Data System (ADS)

    Purdue, Sara; Waters, Samantha; Karthikeyan, Smruthi; Konstantinidis, Kostas; Nenes, Athanasios

    2016-04-01

    Characterization of CCN activity of bacteria, other than a few select types such as Pseudomonas syringae, is limited, especially when looked at in conjunction with corresponding IN activity. The link between these two points is especially important for bacteria as those that have high CCN activity are likely to form an aqueous phase required for immersion freezing. Given the high ice nucleation temperature of bacterial cells, especially in immersion mode, it is important to characterize the CCN and IN activity of many different bacterial strains. To this effect, we developed a droplet freezing assay (DFA) which consists of an aluminum cold plate, cooled by a continuous flow of an ethylene glycol-water mixture, in order to observe immersion freezing of the collected bacteria. Here, we present the initial results on the CCN and IN activities of bacterial samples we have collected in Atlanta, GA. Bacterial strains were collected and isolated from rainwater samples taken from different storms throughout the year. We then characterized the CCN activity of each strain using a DMT Continuous Flow Streamwise Thermal Gradient CCN Counter by exposing the aerosolized bacteria to supersaturations ranging from 0.05% to 0.6%. Additionally, using our new DFA, we characterized the IN activity of each bacterial strain at temperatures ranging from -20oC to 0oC. The combined CCN and IN activity gives us valuable information on how some uncharacterized bacteria contribute to warm and mixed-phase cloud formation in the atmosphere.

  14. Major subtypes of invasive Haemophilus influenzae from 1983 to 1985 in Atlanta, Ga.

    PubMed Central

    Elliott, J A; Pigott, N; Cochi, S L; Facklam, R R

    1990-01-01

    We compared outer membrane protein (OMP) patterns of Haemophilus influenzae isolated in metropolitan Atlanta, Ga., from July 1983 to June 1985. Of 74 randomly selected H. influenzae serotype b, biotype I, isolates (24% of the total number of H. influenzae, and 32% of the total number of H. influenzae serotype b, biotype I, isolates), 66 (89.2%) had the same OMP pattern. Of the remaining eight, five (6.7%) had an identical OMP pattern. The other three isolates had separate and distinct patterns. A greater diversity of OMP patterns was found with H. influenzae serotype b, biotype II, and nonserotypeable H. influenzae. Of the 18 H. influenzae serotype b, biotype II, isolates (5.8% of the total number of H. influenzae isolates), 1 had an OMP pattern similar to that of the predominate biotype I OMP type, 6 (33% of the biotype II) had the same pattern, and 11 had heterogeneous patterns. Of the 19 recoverable, nonserotypeable biotype II isolates (6.8% of the total number of H. influenzae), 18 had different OMP patterns, and no pattern was similar to those observed with serotype b. These findings indicate that most H. influenzae strains isolated during this 2-year period were indistinguishable by serotype, biotype, or OMP patterns. Images PMID:2191007

  15. The motion of floating and submerged objects in the Chattahoochee River, Atlanta, GA.

    PubMed

    Dilen, D R

    1984-10-01

    Two mannikins, one designed to float and one designed to sink, were used to examine the ways in which human bodies move in a river. The floating mannikin was used to examine the movement of a body floating downstream on the surface and to determined the flow patterns of surface currents through bends in the Chattahoochee River in Atlanta, GA. The submerged mannikin was constructed to have a specific gravity of a deceased person (over a range of specific gravities) and was used to examine the motion of a body immediately upon entering the water. The submerged mannikin also was used to examine motion along the bottom of the river. Floating objects near each bank of the Chattahoochee River were found to remain along their respective banks as they moved downstream through the bends in the river. No mechanisms of transport from one bank to the other in the bends was found. The movement of a submerged dummy only occurred at very high river flows. The dummy remained stationary at the place where it reached the bottom for tests over a wide range of specific gravities and a moderate range of flow levels. A discussion of the river conditions (for example, bottom topography, bottom composition, flow rates, and hydraulics) is included. The results of the experiments offer initial guidelines and principles that can be used by officials and agencies involved in the search, rescue, and recovery of bodies in most rivers.

  16. 78 FR 76810 - Information Collection; Environmental Justice and the Urban Forest in Atlanta, GA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-19

    ...In accordance with the Paperwork Reduction Act of 1995, the Forest Service is seeking comments from all interested individuals and organizations on the new information collection, Environmental Justice and the Urban Forest in Atlanta,...

  17. ANALYSIS OF COMPONENTS OF PARTICULATE MATTER (PM2.5) FOR AN EXPOSURE ASSESSMENT STUDY OF TWO SENSITIVE COHORTS IN ATLANTA, GA

    EPA Science Inventory

    Introduction
    An exposure assessment study was conducted in Atlanta, GA during fall 1999 and spring 2000 to examine the short-term effects of exposure to particulate matter and gaseous air pollutants on heart rate variability (HRV). Characterization of particulate matter (PM...

  18. Impacts of cool cities on air quality: A preliminary modeling assessment for Nashville TN, Dallas TX and Atlanta GA

    SciTech Connect

    Taha, Haider

    1998-06-15

    Previous atmospheric modeling efforts that concentrated on the Los Angeles Basin suggested beneficial and significant air quality impacts from cool cities strategies. This paper discusses an extension of similar modeling efforts to three regions, Atlanta GA, Dallas - Ft. Worth TX, and Nashville TN, that experience smog and air quality problems. According to the older ozone air quality standard (120 ppb), these regions were classified as serious, moderate, and marginal, respectively, but may be out of compliance with respect to the newer, 80-ppb/8-hours standard. Results from this exploratory modeling work suggest a range of possible impacts on meteorological and air quality conditions. For example, peak ozone concentrations during each region's respective episode could be decreased by 1-6 ppb (conservative and optimistic scenarios, respectively) in Nashville, 5-15 ppb in Dallas - Fort Worth, and 5-12 ppb in Atlanta following implementation of cool cities. The reductions are generally smaller than those obtained from simulating the Los Angeles Basin but are still significant. In all regions, the simulations suggest, the net, domain-wide effects of cool cities are reductions in ozone mass and improvements in air quality. In Atlanta, Nashville, and Dallas, urban areas benefiting from reduced smog reach up to 8460, 7350, and 12870 km{sup 2} in area, respectively. Results presented in this paper should be taken as exploratory and preliminary. These will most likely change during a more comprehensive modeling study to be started soon with the support of the US Environmental Protection Agency. The main purpose of the present project was to obtain the initial data (emission inventories) for these regions, simulate meteorological conditions, and perform preliminary sensitivity analysis. In the future, additional regions will be simulated to assess the potential of cool cities in improving urban air quality.

  19. Technical report. Graduate Student Focus on Diversity Workshop, 1999 SIAM Annual Meeting, Atlanta, Georgia, May 12, 1999

    SciTech Connect

    1999-05-12

    The Third SIAM Graduate Student Focus on Diversity workshop was held May 12 at the Sheraton Atlanta Hotel on the first day of the 1999 SIAM Annual Meeting. The day-long workshop consisted of several different activities: eight technical talks by under-represented minority graduate students, a lively panel discussion concerning the benefits of undergraduate summer research programs, informal luncheon and pizza breaks to foster social interaction, and an evening forum with candid discussions of graduate school experiences from a minority graduate student perspective. These sessions were open to the entire SIAM community and served to highlight the progress, achievements, and aspirations of the workshop participants.

  20. Advancing Residential Retrofits in Atlanta

    SciTech Connect

    Jackson, Roderick K; Kim, Eyu-Jin; Roberts, Sydney; Stephenson, Robert

    2012-07-01

    This report will summarize the home energy improvements performed in the Atlanta, GA area. In total, nine homes were retrofitted with eight of the homes having predicted source energy savings of approximately 30% or greater based on simulated energy consumption.

  1. Road Dust Lead (Pb) in Two Neighborhoods of Urban Atlanta, (GA, USA)

    PubMed Central

    Deocampo, Daniel M.; Reed, Jack; Kalenuik, Alexander P.

    2012-01-01

    Road dust continues to be a major potential reservoir of Pb in the urban environment, and an important potential component of child Pb exposure. This study presents ICP-AES analyses of metals in 72 samples of road dust (<250 µm) collected in the urban core of Atlanta, Georgia. In the Downtown area, median Pb concentrations are ~63 mg/kg Pb, with high values of 278 mg/kg. For comparison, median Pb values in a nearby residential neighborhood (also in the urban core) were ~93 mg/kg, with a high of 972 mg/kg. Geospatial variability is high, with significant variation observed over tens to hundreds of meters. Spearman Rank Correlation tests suggest that Pb and other metals (Cu, Ni, V, Zn) are associated with iron and manganese oxide phases in the residential area, as reported in other cities. However, Pb in the Downtown area is not correlated with the others, suggesting a difference in source or transport history. Given these complexities and the expected differences between road dust and soil Pb, future efforts to assess exposure risk should therefore be based on spatially distributed sampling at very high spatial resolution. PMID:22829787

  2. Custodial Homes, Therapeutic Homes, and Parental Acceptance: Parental Experiences of Autism in Kerala, India and Atlanta, GA USA.

    PubMed

    Sarrett, Jennifer C

    2015-06-01

    The home is a critical place to learn about cultural values of childhood disability, including autism and intellectual disabilities. The current article describes how the introduction of autism into a home and the availability of intervention options change the structure and meaning of a home and reflect parental acceptance of a child's autistic traits. Using ethnographic data from Kerala, India and Atlanta, GA USA, a description of two types of homes are developed: the custodial home, which is primarily focused on caring for basic needs, and the therapeutic home, which is focused on changing a child's autistic traits. The type of home environment is respondent to cultural practices of child rearing in the home and influences daily activities, management, and care in the home. Further, these homes differ in parental acceptance of their autistic children's disabilities, which is critical to understand when engaging in international work related to autism and intellectual disability. It is proposed that parental acceptance can be fostered through the use of neurodiverse notions that encourage autism acceptance.

  3. National Association for Research in Science Teaching 52nd Annual Meeting, Abstracts of Presented Papers (Atlanta, Georgia, March 21-23, 1979).

    ERIC Educational Resources Information Center

    White, Arthur L., Ed.

    This publication contains abstracts of papers presented at the 52nd annual meeting of the National Association for Research in Science Teaching (NARST), Atlanta, Georgia, March 21-23, 1979. Papers relate to science teacher education (preservice and inservice), cognitive development, learning, instruction, teacher and student behaviors, research…

  4. 2. Photocopy of photograph (original photograph in possession of Atlanta ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. Photocopy of photograph (original photograph in possession of Atlanta Housing Authority, Atlanta, GA). Photographer unknown, circa 1940. Aerial view of Clark Howell Homes, center, Techwood Homes, left, Georgia Institute of Technology, bottom. - Clark Howell Homes (Public Housing), Bounded by North Avenue, Lovejoy Street, Mills Street & Luckie Street, Atlanta, Fulton County, GA

  5. 1. Photocopy of photograph (original photograph in possession of Atlanta ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Photocopy of photograph (original photograph in possession of Atlanta Housing Authority, Atlanta, GA). Photographer unknown, circa 1940. Aerial view, Clark Howell Homes, left, Techwood Homes, right, Georgia Institute of Technology, top, right. - Clark Howell Homes (Public Housing), Bounded by North Avenue, Lovejoy Street, Mills Street & Luckie Street, Atlanta, Fulton County, GA

  6. Photocopy of photograph (original photograph in possession of Atlanta Housing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photocopy of photograph (original photograph in possession of Atlanta Housing Authority, Atlanta, GA). Photographer unknown, June, 1940. VIEW OF STORE AND ADMINISTRATION BUILDING (RIGHT), BUILDING 4 (CENTER) AND BUILDING 5 RIGHT, FROM NORTH FACING SOUTH ALONG TECHWOOD DRIVE. - Techwood Homes (Public Housing), Bounded by North Avenue, Parker Street, William Street & Lovejoy Street, Atlanta, Fulton County, GA

  7. 8. Photocopy of photograph (original photograph in possession of Atlanta ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. Photocopy of photograph (original photograph in possession of Atlanta Housing Authority, Atlanta, GA). Photographer unknown, circa 1940. Contextual view of Building E-7 (left), Building E-5 (center), and Building E-6 right), from west side of Luckie Street facing northeast. - Clark Howell Homes (Public Housing), Bounded by North Avenue, Lovejoy Street, Mills Street & Luckie Street, Atlanta, Fulton County, GA

  8. 3. Photocopy of photograph (original photograph in possession of Atlanta ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. Photocopy of photograph (original photograph in possession of Atlanta Housing Authority, Atlanta, GA). Photographer unknown, circa 1945. Typical streetscape view, Clark Howell Homes. - Clark Howell Homes (Public Housing), Bounded by North Avenue, Lovejoy Street, Mills Street & Luckie Street, Atlanta, Fulton County, GA

  9. 4. Photocopy of photograph (original photograph in possession of Atlanta ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. Photocopy of photograph (original photograph in possession of Atlanta Housing Authority, Atlanta, GA). Photographer unknown, circa 1940. Clark Howell Homes, 219 Mills Street, left, 199 Mills Street, center, 404 Lovejoy Street, right, under construction. From west facing east. - Clark Howell Homes (Public Housing), Bounded by North Avenue, Lovejoy Street, Mills Street & Luckie Street, Atlanta, Fulton County, GA

  10. 11. Photocopy of photograph (original photograph in possession of Atlanta ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. Photocopy of photograph (original photograph in possession of Atlanta Housing Authority, Atlanta, GA). Photographer unknown, circa 1945. View of rear entrances and yards of Building A-5, from northwest facing southeast. - Clark Howell Homes (Public Housing), Bounded by North Avenue, Lovejoy Street, Mills Street & Luckie Street, Atlanta, Fulton County, GA

  11. Photocopy of photograph (original photograph in possession of Atlanta Housing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photocopy of photograph (original photograph in possession of Atlanta Housing Authority, Atlanta, GA). Photographer unknown, 1981. AERIAL VIEW IN CONTEXT, TECHWOOD HOMES, FROM SOUTHEAST FACING NORTHWEST. - Techwood Homes (Public Housing), Bounded by North Avenue, Parker Street, William Street & Lovejoy Street, Atlanta, Fulton County, GA

  12. 5. Photocopy of photograph (original photograph in possession of Atlanta ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. Photocopy of photograph (original photograph in possession of Atlanta Housing Authority, Atlanta, GA). Photographer unknown, circa July, 1940. Public opening, Clark Howell Homes. 411 Luckie Street, left. From east facing west. - Clark Howell Homes (Public Housing), Bounded by North Avenue, Lovejoy Street, Mills Street & Luckie Street, Atlanta, Fulton County, GA

  13. 13. Photocopy of photograph (original photograph in possession of Atlanta ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. Photocopy of photograph (original photograph in possession of Atlanta Housing Authority, Atlanta, GA). Photographer unknown, circa 1940. View of apartment interior, kitchen, living room, and bedrooms. - Clark Howell Homes (Public Housing), Bounded by North Avenue, Lovejoy Street, Mills Street & Luckie Street, Atlanta, Fulton County, GA

  14. Photocopy of photograph (original photograph in possession of Atlanta Housing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photocopy of photograph (original photograph in possession of Atlanta Housing Authority, Atlanta, GA). Photographer unknown, circa 1940. VIEW OF BUILDING 16, FROM NORTHEAST FACING SOUTHWEST ACROSS TECHWOOD DRIVE. - Techwood Homes (Public Housing), Bounded by North Avenue, Parker Street, William Street & Lovejoy Street, Atlanta, Fulton County, GA

  15. Photocopy of photograph (original photograph in possession of Atlanta Housing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photocopy of photograph (original photograph in possession of Atlanta Housing Authority, Atlanta, GA). Photographer unknown, circa 1940. VIEW OF PLAYGROUND BEHIND BUILDING X, FROM WEST FACING EAST. - Techwood Homes (Public Housing), Bounded by North Avenue, Parker Street, William Street & Lovejoy Street, Atlanta, Fulton County, GA

  16. 12. Photocopy of photograph (original photograph in possession of Atlanta ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. Photocopy of photograph (original photograph in possession of Atlanta Housing Authority, Atlanta, GA). Photographer unknown, circa 1945. View across park and playground between Techwood Homes and Clark Howell Homes, facing west with Clark Howell Homes in background. - Clark Howell Homes (Public Housing), Bounded by North Avenue, Lovejoy Street, Mills Street & Luckie Street, Atlanta, Fulton County, GA

  17. Photocopy of photograph (original photograph in possession of Atlanta Housing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photocopy of photograph (original photograph in possession of Atlanta Housing Authority, Atlanta, GA). Photographer unknown, circa 1940. VIEW OF WADING POOL, BUILDING 12 IN BACKGROUND (LEFT), FROM SOUTHEAST FACING NORTHWEST. - Techwood Homes (Public Housing), Bounded by North Avenue, Parker Street, William Street & Lovejoy Street, Atlanta, Fulton County, GA

  18. 10. Photocopy of photograph (original photograph in possession of Atlanta ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. Photocopy of photograph (original photograph in possession of Atlanta Housing Authority, Atlanta, GA). Photographer unknown, circa 1940. View of east end and north side of Building E-1, from east side of Venable Street facing west. Luckie Street visible in background. - Clark Howell Homes (Public Housing), Bounded by North Avenue, Lovejoy Street, Mills Street & Luckie Street, Atlanta, Fulton County, GA

  19. Photocopy of photograph (original photograph in possession of Atlanta Housing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photocopy of photograph (original photograph in possession of Atlanta Housing Authority, Atlanta, GA). Photographer unknown, June, 1940. VIEW OF BUILDING 19, FROM EAST FACING WEST, ACROSS TECHWOOD DRIVE. - Techwood Homes (Public Housing), Bounded by North Avenue, Parker Street, William Street & Lovejoy Street, Atlanta, Fulton County, GA

  20. Atlanta Papers: Caucus on Social Theory and Art Education. Proceedings of the Inaugural Session of the Annual Meeting of the National Art Education Association (Atlanta, Georgia, 1980).

    ERIC Educational Resources Information Center

    Caucus on Social Theory and Art Education.

    Papers included in this collection which were originally presented at the inaugural meeting of the Caucus on Social Theory and Art Education are: "Introduction: Toward a Socially Progressive Conception of Art Education" (R. Bersson); "Established Ways of Thinking" (J. Hobbs); "Needed: A New View of Art and Emotions" (A. Sherman); "Statement for…

  1. 7. Photocopy of photograph (original photograph in possession of Atlanta ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. Photocopy of photograph (original photograph in possession of Atlanta Housing Authority, Atlanta, GA). Photographer unknown, circa 1939. Typical dwellings demolished for construction of Clark Howell Homes. View of west side of McAfee Street, from intersection with Gresham Street (now Clark Howell Place) facing northwest. - Clark Howell Homes (Public Housing), Bounded by North Avenue, Lovejoy Street, Mills Street & Luckie Street, Atlanta, Fulton County, GA

  2. 9. Photocopy of photograph (original photograph in possession of Atlanta ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. Photocopy of photograph (original photograph in possession of Atlanta Housing Authority, Atlanta, GA). Photographer unknown, circa 1940. View of Hunnicutt Street under construction, from Venable Street facing east. Buildings A-2, D-4, C-5, and A-5 at left, Building J-12 at right. W.W. Orr Medical Building visible in background at center. - Clark Howell Homes (Public Housing), Bounded by North Avenue, Lovejoy Street, Mills Street & Luckie Street, Atlanta, Fulton County, GA

  3. Disparities in herpes simplex virus type 2 infection between black and white men who have sex with men in Atlanta, GA

    PubMed Central

    Okafor, Netochukwu; Rosenberg, Eli S; Luisi, Nicole; Sanchez, Travis; del Rio, Carlos; Sullivan, Patrick S; Kelley, Colleen F

    2015-01-01

    Summary Background HIV disproportionately affects black men who have sex with men, and herpes simplex virus type 2 is known to increase acquisition of HIV. However, data on racial disparities in herpes simplex virus type 2 prevalence and risk factors are limited among men who have sex with men in the United States. Methods InvolveMENt was a cohort study of black and white HIV-negative men who have sex with men in Atlanta, GA. Univariate and multivariate cross-sectional associations with herpes simplex virus type 2 seroprevalence were assessed among 455 HIV-negative men who have sex with men for demographic, behavioral, and social determinant risk factors using logistic regression. Results Seroprevalence of herpes simplex virus type 2 was 23% (48/211) for black and 16% (38/244) for white men who have sex with men (p = 0.05). Education, poverty, drug/alcohol use, incarceration, circumcision, unprotected anal intercourse, and condom use were not associated with herpes simplex virus type 2. In multivariate analyses, black race for those ≤25 years, but not >25 years, and number of sexual partners were significantly associated. Conclusions Young black men who have sex with men are disproportionately affected by herpes simplex virus type 2, which may contribute to disparities in HIV acquisition. An extensive assessment of risk factors did not explain this disparity in herpes simplex virus type 2 infection suggesting differences in susceptibility or partner characteristics. PMID:25246424

  4. Disparities in herpes simplex virus type 2 infection between black and white men who have sex with men in Atlanta, GA.

    PubMed

    Okafor, Netochukwu; Rosenberg, Eli S; Luisi, Nicole; Sanchez, Travis; del Rio, Carlos; Sullivan, Patrick S; Kelley, Colleen F

    2015-09-01

    HIV disproportionately affects black men who have sex with men, and herpes simplex virus type 2 is known to increase acquisition of HIV. However, data on racial disparities in herpes simplex virus type 2 prevalence and risk factors are limited among men who have sex with men in the United States. InvolveMENt was a cohort study of black and white HIV-negative men who have sex with men in Atlanta, GA. Univariate and multivariate cross-sectional associations with herpes simplex virus type 2 seroprevalence were assessed among 455 HIV-negative men who have sex with men for demographic, behavioural and social determinant risk factors using logistic regression. Seroprevalence of herpes simplex virus type 2 was 23% (48/211) for black and 16% (38/244) for white men who have sex with men (p = 0.05). Education, poverty, drug/alcohol use, incarceration, circumcision, unprotected anal intercourse, and condom use were not associated with herpes simplex virus type 2. In multivariate analyses, black race for those ≤25 years, but not >25 years, and number of sexual partners were significantly associated. Young black men who have sex with men are disproportionately affected by herpes simplex virus type 2, which may contribute to disparities in HIV acquisition. An extensive assessment of risk factors did not explain this disparity in herpes simplex virus type 2 infection suggesting differences in susceptibility or partner characteristics.

  5. Bright Meteor Lights Up Atlanta Skies

    NASA Video Gallery

    This video shows a very bright meteor that streaked over the skies of Atlanta, Ga., on the night of Aug. 28, 2011. The view is from an all sky camera in Cartersville, Ga., operated by NASA’s Mars...

  6. 76 FR 37781 - Foreign-Trade Zone 26; Atlanta, GA; Application for Temporary/Interim Manufacturing Authority...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-28

    ... Manufacturing Authority; Makita Corporation of America; (Hand- Held Power Tool and Gasoline/Electric-Powered Garden Product Manufacturing); Buford, GA An application has been submitted to the Executive Secretary of..., requesting temporary/interim manufacturing (T/IM) authority within FTZ 26 at the Makita Corporation...

  7. The International Year of Astronomy in Atlanta

    NASA Astrophysics Data System (ADS)

    De Pree, Christopher G.

    2010-01-01

    The greater Atlanta metropolitan area has been able to participate in the International Year of Astronomy in a number of ways, through local and national funding. The Hartsfield-Atlanta International airport has hosted a 7 month exhibition of over 50 images in From Earth to the Universe (FETTU), and the Atlanta Center for the Visually Impaired (CVI) has hosted a two month exhibition of tactile astronomical images at their downtown education and outreach facility. Connected to the FETTU exhibit, 9 locations in Atlanta are home to scaled images of the planets and the Sun in a project entitled the Metro Atlanta Solar System (MASS). Centered at Agnes Scott College in Decatur, GA, the goal of MASS is help make the sizes and distances between planets more understandable. In addition, Agnes Scott College as a whole has connected to the IYA celebration in declaring Project Galileo: Revealing Hidden Worlds as its curricular focus the 2009-2010 academic year. I will describe the various Atlanta projects and the ways in which the IYA has enriched the curricular life of the college.

  8. Summary of Needs and Opportunities from the 2011 Residential Energy Efficiency Meeting: Atlanta, Georgia, March 16-18, 2011

    SciTech Connect

    none,

    2011-05-01

    This meeting brought together more than 200 professionals representing organizations with vested interest in energy efficiency improvements in residential buildings. Participants identified or reinforced a wide variety of needs and issues associated with delivering high-performance homes in both new and existing home scenarios,

  9. Selected papers from the 12th International Workshop on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS 2012) (Atlanta, GA, USA, 2-5 December 2012)

    NASA Astrophysics Data System (ADS)

    Allen, Mark G.; Lang, Jeffrey

    2013-11-01

    Welcome to this special section of the Journal of Micromechanics and Microengineering (JMM). This section, co-edited by myself and by Professor Jeffrey Lang of the Massachusetts Institute of Technology, contains expanded versions of selected papers presented at the Power MEMS meeting held in Atlanta, GA, USA, in December of 2012. Professor Lang and I had the privilege of co-chairing Power MEMS 2012, the 12th International Workshop on Micro and Nanotechnology for Power Generation and Energy Conversion Applications. The scope of the PowerMEMS series of workshops ranges from basic principles, to materials and fabrication, to devices and systems, to applications. The many applications of power MEMS (microelectromehcanical systems) range from MEMS-enabled energy harvesting, storage, conversion and conditioning, to integrated systems that manage these processes. Why is the power MEMS field growing in importance? Smaller-scale power and power supplies (microwatts to tens of watts) are gaining in prominence due to many factors, including the ubiquity of low power portable electronic equipment and the proliferation of wireless sensor nodes that require extraction of energy from their embedding environment in order to function. MEMS manufacturing methods can be utilized to improve the performance of traditional power supply elements, such as allowing batteries to charge faster or shrinking the physical size of passive elements in small-scale power supplies. MEMS technologies can be used to fabricate energy harvesters that extract energy from an embedding environment to power wireless sensor nodes, in-body medical implants and other devices, in which the harvesters are on the small scales that are appropriately matched to the overall size of these microsystems. MEMS can enable the manufacturing of energy storage elements from nontraditional materials by bringing appropriate structure and surface morphology to these materials as well as fabricating the electrical interfaces

  10. Explaining Racial Disparities in HIV Incidence in a Prospective Cohort of Black and White Men Who Have Sex With Men in Atlanta, GA: A Prospective Observational Cohort Study

    PubMed Central

    Sullivan, Patrick S; Rosenberg, Eli S; Sanchez, Travis H; Kelley, Colleen; Luisi, Nicole; Cooper, Hannah; Diclemente, Ralph; Frew, Paula; Salazar, Laura F; del Rio, Carlos; Mulligan, Mark J; Peterson, John

    2015-01-01

    Purpose To describe factors associated with racial disparities in HIV incidence among men who have sex with men (MSM) in the United States. Methods In a longitudinal cohort of black and white HIV-negative MSM in Atlanta, HIV incidence rates were compared by race. Incidence hazard ratios (HR) between black and white MSM were estimated with an age-scaled Cox proportional hazards model. A change-in-estimate approach was used to understand mediating time-independent and -dependent factors that accounted for the elevated HR. Results Thirty-two incident HIV infections occurred among 260 black and 302 white MSM during 823 person-years (PY) of followup. HIV incidence was higher among black MSM (6.5/100PY; 95% CI: 4.2, 9.7) than white MSM (1.7/100PY; CI: 0.7, 3.3), and highest among young (18–24 years) black MSM (10.9/100PY; CI: 6.2, 17.6). The unadjusted hazard of HIV infection for black MSM was 2.9 (CI: 1.3–6.4) times that of white MSM; adjustment for health insurance status and partner race explained effectively all of the racial disparity. Conclusions Relative to white MSM in Atlanta, black MSM, particularly young black MSM, experienced higher HIV incidence that was not attributable to individual risk behaviors. In a setting where partner pool risk is a driver of disparities, it is also important to maximize care and treatment for HIV-positive MSM. PMID:25911980

  11. SEMI-CONTINUOUS AEROSOL CARBON MEASUREMENTS: COMPARISON OF ATLANTA SUPERSITE MEASUREMENTS

    EPA Science Inventory

    An intensive field campaign of the Atlanta Supersite Experiment was carried out at a ground-based measurement site on Jefferson Street in midtown Atlanta, GA, from 3 August to 1 September, 1999. This paper examines the semi-continuous particulate organic and elemental measureme...

  12. THE ATLANTA SUPERSITE PROJECT

    EPA Science Inventory

    The Atlanta Supersites project is the first of two Supersites projects to be established during Phase I of EPA's Supersites Program; Phase 11 is being established through a Request for Assistance. The other initial project is in Fresno, California. The Supersites Program is par...

  13. Simulation of Urban Heat Island Mitigation Strategies in Atlanta, GA Using High-Resolution Land Use/Land Cover Data Set to Enhance Meteorological Modeling

    NASA Technical Reports Server (NTRS)

    Crosson, William L.; Dembek, Scott; Estes, Maurice G., Jr.; Limaye, Ashutosh S.; Lapenta, William; Quattrochi, Dale A.; Johnson, Hoyt; Khan, Maudood

    2006-01-01

    The specification of land use/land cover (LULC) and associated land surface parameters in meteorological models at all scales has a major influence on modeled surface energy fluxes and boundary layer states. In urban areas, accurate representation of the land surface may be even more important than in undeveloped regions due to the large heterogeneity within the urban area. Deficiencies in the characterization of the land surface related to the spatial or temporal resolution of the data, the number of LULC classes defined, the accuracy with which they are defined, or the degree of heterogeneity of the land surface properties within each class may degrade the performance of the models. In this study, an experiment was conducted to test a new high-resolution LULC data set for meteorological simulations for the Atlanta, Georgia metropolitan area using a mesoscale meteorological model and to evaluate the effects of urban heat island (UHI) mitigation strategies on modeled meteorology for 2030. Simulation results showed that use of the new LULC data set reduced a major deficiency of the land use data used previously, specifically the poor representation of urban and suburban land use. Performance of the meteorological model improved substantially, with the overall daytime cold bias reduced by over 30%. UHI mitigation strategies were projected to offset much of a predicted urban warming between 2000 and 2030. In fact, for the urban core, the cooling due to UHI mitigation strategies was slightly greater than the warming associated with urbanization over this period. For the larger metropolitan area, cooling only partially offset the projected warming trend.

  14. 77 FR 1051 - General Conference Committee of the National Poultry Improvement Plan; Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-09

    ... Animal and Plant Health Inspection Service General Conference Committee of the National Poultry.... SUMMARY: We are giving notice of a meeting of the General Conference Committee of the National Poultry...., Atlanta, GA. FOR FURTHER INFORMATION CONTACT: Dr. C. Stephen Roney, Senior Coordinator, National...

  15. 75 FR 5353 - Proposal Review Panel for Chemistry; Notice of Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-02

    ... Proposal Review Panel for Chemistry; Notice of Meeting In accordance with the Federal Advisory Committee... and The University of Massachusetts, Proposal Review Panel for Chemistry ( 1191). Dates and Times...: Department of Chemistry, Georgia Institute of Technology, Atlanta, GA 30332. Department of Chemistry,...

  16. Atlanta's Own "Hall" of Famer

    ERIC Educational Resources Information Center

    Maxwell, Lesil A.

    2008-01-01

    This article features Beverly L. Hall, poised to become one of the longest-serving superintendents of the Atlanta schools. When she came to Atlanta in 1999, student achievement was sliding downward, teacher morale was dismal, and enrollment was falling as parents pulled their children out of the school system. Under the superintendent's driving…

  17. Maintaining Relevancy in Programs of Agriculture. Proceedings: Southern Regional Meeting, Land Grant College and University Presidents and Administrators of Agriculture (Atlanta, Georgia, April 20-21, 1972).

    ERIC Educational Resources Information Center

    Southern Regional Education Board, Atlanta, GA. Inst. for Higher Educational Opportunity.

    Recommendations for maintaining relevant programs which resulted from this meeting of college and university presidents and administrators are applicable to all colleges and universities offering programs of agriculture in the region. Given in this report are two major presentations entitled "The Integration of Knowledge in a Specialized Society"…

  18. Environmental Public Health Surveillance for Exposure to Respiratory Health Hazards: A Joint NASA/CDC Project to Use Remote Sensing Data for Estimating Airborne Particulate Matter Over the Atlanta, Georgia Metropolitan Area

    NASA Technical Reports Server (NTRS)

    Quattrochi, Dale A.; Al-Hamdan, Mohammad; Estes, Maurice; Crosson, William

    2007-01-01

    As part of the National Environmental Public Health Tracking Network (EPHTN) the National Center for Environmental Health (NCEH) at the Centers for Disease Control and Prevention (CDC) is leading a project called Health and Environment Linked for Information Exchange (HELiX-Atlanta). The goal of developing the National Environmental Public Health Tracking Network is to improve the health of communities. Currently, few systems exist at the state or national level to concurrently track many of the exposures and health effects that might be associated with environmental hazards. An additional challenge is estimating exposure to environmental hazards such as particulate matter whose aerodynamic diameter is less than or equal to 2.5 micrometers (PM2.5). HELIX-Atlanta's goal is to examine the feasibility of building an integrated electronic health and environmental data network in five counties of Metropolitan Atlanta, GA. NASA Marshall Space Flight Center (NASA/MSFC) is collaborating with CDC to combine NASA earth science satellite observations related to air quality and environmental monitoring data to model surface estimates of PM2.5 concentrations that can be linked with clinic visits for asthma. While use of the Air Quality System (AQS) PM2.5 data alone could meet HELIX-Atlanta specifications, there are only five AQS sites in the Atlanta area, thus the spatial coverage is not ideal. We are using NASA Moderate Resolution Imaging Spectroradiometer (MODIS) satellite Aerosol Optical Depth (AOD) data for estimating daily ground level PM2.5 at 10 km resolution over the metropolitan Atlanta area supplementing the AQS ground observations and filling their spatial and temporal gaps.

  19. NARSTO EPA SS ATLANTA RAPID SPMS DATA

    Atmospheric Science Data Center

    2014-04-25

    NARSTO EPA SS ATLANTA RAPID SPMS DATA Project Title:  NARSTO ...   Order Data Guide Documents:  Atlanta SPMS Guide EPA Sites Get Google Earth ... Data:  Environmental Protection Agency Supersites Atlanta, Georgia SCAR-B Block:  ...

  20. Atlanta Public Schools Latin Guide.

    ERIC Educational Resources Information Center

    Atlanta Public Schools, GA.

    This teacher's guide outlines the basic objectives and the content of the Atlanta Public Schools Latin program and suggests resources and methods to achieve the stated goals. The philosophy and general objectives of the program are presented. Course outlines include: (1) Beginning Latin, (2) Intermediate Latin, (3) Vergil's "Aeneid," (4) Ovid:…

  1. COMPARISON OF INTEGRATED SAMPLERS FOR MASS AND COMPOSITION DURING THE 1999 ATLANTA SUPERSITES PROJECT

    EPA Science Inventory

    The first of EPA's Particulate Matter (PM) Supersites projects was established in Atlanta, GA during the summer of 1999 in conjunction with the Southern Oxidants Study. The short-term primary focus was a one month intensive field campaign to evaluate advanced PM measurement me...

  2. Satellites monitor Atlanta regional development

    USGS Publications Warehouse

    Todd, William J.; Blackmon, C.C.; Rudasill, R.G.

    1979-01-01

    Since the adoption of a Regional Development Plan in 1975, the Atlanta Regional Commission has investigated methods for monitoring regional development patterns in a periodic, efficient manner. A promising approach appears to be the use of Landsat satellite data. In cooperation with the Earth Resources Observation Systems (EROS) Data Center, the commission used machine processing of digital temporal overlays of Landsat data collected in 1972, 1974 and 1976 to detect land use and land cover changes in the Atlanta metropolitan area. Results of the analysis revealed the conversion of forested and open space areas to residential, commercial and industrial land use in the urban-rural fringe zone from 1972 to 1974 and from 1974 to 1976. The study indicated that a land use and land cover change-detection program may be used to revise small-area forecasts of land use, population and employment made by planning models.

  3. Assessing the Impacts of Hartsfield-Jackson Atlanta International Airport on Particulate Matter and Ozone in Atlanta Metropolitan Area

    NASA Technical Reports Server (NTRS)

    Unal, Alper; Odman, M. Talat; Russell, Armistead G.

    2005-01-01

    The goal of this study was to determine, through modeling, the impact of aircraft emissions on regional air quality, especially in regard to fine particulate matter (PM(2.5)) as well as ozone and other pollutants. For this, we focused on Hartsfield-Jackson Atlanta International Airport which is the busiest airport in the world based on passenger traffic (AIC, 2003). Hartsfield-Jackson serves the metropolitan Atlanta area where air quality does not meet national standards. Emissions from mobile and industrial sources (including several large electric power generating utilities) are the major contributors to the area's air pollution. In this study, we assessed the impact of Hartsfield-Jackson Airport on air quality around Atlanta, Georgia, and compared it to the impacts of other emission sources in the area. The assessment was built upon other, related air quality studies involving both field and modeling components. To achieve the objectives, first a detailed inventory was developed for aircraft and other emissions at Hartsfield-Jackson Atlanta International Airport. Then, air quality simulations were performed to relate these emissions to regional air quality around Atlanta. The Community Multiscale Air Quality Model (CMAQ) was used as the modeling platform. The period of August 11-20 2000 was selected as the episode to be modeled in this study. Prior modeling of this episode during the Fall Line Air Quality Study (FAQS) and availability of additional PM(2.5) measurements for evaluation played a major role in this selection. Meteorological data for this episode as well as emission data for sources other than aircrafts were already available from FAQS.

  4. The Atlanta tornado of 1975

    NASA Technical Reports Server (NTRS)

    Greneker, E. F.; Wilson, C. S.; Metcalf, J. I.

    1976-01-01

    Joint observations by radar and high-frequency sferics detectors at Georgia Institute of Technology provided unique data on the Atlanta tornado of Mar. 24, 1975. The classic hook echo was detected by radar at a range of about 26 km, 15 min before the tornado touched down. While the tornado was on the ground the sferics burst rate was very low, despite very high values recorded immediately before and after this interval. This observation, together with visual reports of a strong cloud-to-ground discharge at the time of tornado touchdown, suggests an interaction of the tornado with the electric field of the storm.

  5. Limited spillover to humans from West Nile Virus viremic birds in Atlanta, Georgia.

    PubMed

    Levine, Rebecca S; Mead, Daniel G; Kitron, Uriel D

    2013-11-01

    West Nile Virus (WNV) is a mosquito-borne pathogen that impacts the health of its passerine bird hosts as well as incidentally infected humans in the United States. Intensive enzootic activity among the hosts and vectors does not always lead to human outbreaks, as is the situation throughout much of the southeastern United States. In Georgia, substantial yearly evidence of WNV in the mosquito vectors and avian hosts since 2001 has only led to 324 human cases. Although virus has been consistently isolated from mosquitoes trapped in Atlanta, GA, little is known about viral activity among the passerine hosts. A possible reason for the suppression of WNV spillover to humans is that viremic birds are absent from high human-use areas of the city. To test this hypothesis, multiseason, multihabitat, longitudinal WNV surveillance for active WNV viremia was conducted within the avian host community of urban Atlanta by collection of blood samples from wild passerine birds in five urban microhabitats. WNV was isolated from the serum of six blood samples collected from 630 (0.95%) wild passerine birds in Atlanta during 2010-2012, a proportion similar to that found in the Chicago, IL, area in 2005, when over 200 human cases were reported. Most of the viremic birds were Northern Cardinals, suggesting they may be of particular importance to the WNV transmission cycle in Georgia. Results indicated active WNV transmission in all microhabitats of urban Atlanta, except in the old-growth forest patches. The number of viremic birds was highest in Zoo Atlanta, where 3.5% of samples were viremic. Although not significant, these observations may suggest a possible transmission reduction effect of urban old-growth forests and a potential role in WNV amplification for Zoo Atlanta. Overall, spillover to humans remains a rare occurrence in urban Atlanta settings despite active WNV transmission in the avian population.

  6. Limited Spillover to Humans from West Nile Virus Viremic Birds in Atlanta, Georgia

    PubMed Central

    Mead, Daniel G.; Kitron, Uriel D.

    2013-01-01

    Abstract West Nile Virus (WNV) is a mosquito-borne pathogen that impacts the health of its passerine bird hosts as well as incidentally infected humans in the United States. Intensive enzootic activity among the hosts and vectors does not always lead to human outbreaks, as is the situation throughout much of the southeastern United States. In Georgia, substantial yearly evidence of WNV in the mosquito vectors and avian hosts since 2001 has only led to 324 human cases. Although virus has been consistently isolated from mosquitoes trapped in Atlanta, GA, little is known about viral activity among the passerine hosts. A possible reason for the suppression of WNV spillover to humans is that viremic birds are absent from high human-use areas of the city. To test this hypothesis, multiseason, multihabitat, longitudinal WNV surveillance for active WNV viremia was conducted within the avian host community of urban Atlanta by collection of blood samples from wild passerine birds in five urban microhabitats. WNV was isolated from the serum of six blood samples collected from 630 (0.95%) wild passerine birds in Atlanta during 2010–2012, a proportion similar to that found in the Chicago, IL, area in 2005, when over 200 human cases were reported. Most of the viremic birds were Northern Cardinals, suggesting they may be of particular importance to the WNV transmission cycle in Georgia. Results indicated active WNV transmission in all microhabitats of urban Atlanta, except in the old-growth forest patches. The number of viremic birds was highest in Zoo Atlanta, where 3.5% of samples were viremic. Although not significant, these observations may suggest a possible transmission reduction effect of urban old-growth forests and a potential role in WNV amplification for Zoo Atlanta. Overall, spillover to humans remains a rare occurrence in urban Atlanta settings despite active WNV transmission in the avian population. PMID:24107200

  7. The Distribution of Segregation in Atlanta

    ERIC Educational Resources Information Center

    Meade, Anthony

    1972-01-01

    A prediction from ecological theory relating the distribution of residential segregation between inner and outer zones of a metropolitan area to conditions of population growth, expansion, etc. was tested using 1960 data on the Atlanta standard metropolitan statistical area. (JM)

  8. Overview of the 1999 Atlanta Supersite Project

    NASA Astrophysics Data System (ADS)

    Solomon, Paul A.; Chameides, William; Weber, Rodney; Middlebrook, Ann; Kiang, C. S.; Russell, Armistead G.; Butler, Andre; Turpin, Barbara; Mikel, Dennis; Scheffe, Richard; Cowling, Ellis; Edgerton, Eric; St. John, James; Jansen, John; McMurry, Peter; Hering, Susanne; Bahadori, Tina

    2003-04-01

    This paper presents an overview of the 1999 Atlanta Supersite Project coordinated through the Southern Oxidants Study and Georgia Institute of Technology (GIT) and funded by the U.S. Environmental Protection Agency (EPA) along with other sponsors who provided in-kind support primarily through existing studies. The Atlanta Supersite Project was located at the existing Southeastern Aerosol Research Characterization Study (SEARCH)/Aerosol Research Inhalation Epidemiology Study (ARIES) site on Jefferson Street in NW Atlanta, Georgia. The primary objective of the Atlanta Supersite Project was to evaluate and compare advanced measurement methods for particulate matter mass and its components. Methods included filter- and denuder-based time-integrated or discrete samplers, a variety of semicontinuous methods measuring mass, its major components (sulfate, nitrate, ammonium, organic carbon, elemental carbon, trace elements) and gas-phase precursors, and for the first time ever, a comparison among particle mass spectrometers; four in total. These data were complemented by meteorological data as well as gas-phase criteria pollutant measurements and other supplemental data such as particle physical properties, volatile organic compounds (VOC), oxygenated VOC, and NOy. The primary and supplemental data also were used to better understand the formation and accumulation of particulate matter in Atlanta and to better understand source-receptor relationships. This paper overviews the study, summarizing objectives, the site and measurements, and the relative reference data used for comparisons, and it overviews the meteorological and chemical characteristics of pollution in Atlanta during the study, puts the study in context of Atlanta and the southeast United States, and finally summarizes the key findings from the over 30 publications published, submitted, or in preparation. This paper also provides as complete a list as is currently available of those publications. Others

  9. Clean Cities Award Winning Coalition: Atlanta

    SciTech Connect

    ICF Kaiser

    1999-05-19

    The Atlanta Clean City was the first to join the program in 1993, and has been successfully spreading the word about the benefits of alternative fuels ever since. They have already surpassed their year 2000 goal of operating more than 2,600 alternative fuel vehicles (AFVs). More than 30 stakeholders continue to help spur the Atlanta AFV market development by implementing innovative alternative fuel projects. Stakeholders actively support legislation that encourages the use of AFVs and sponsor workshops on advancing the choice.

  10. 78 FR 28940 - Environmental Impact Statement for the Atlanta to Charlotte Portion of the Southeast High Speed...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-16

    ... Southeast High Speed Rail Corridor AGENCY: Federal Rail Administration (FRA), DOT. ACTION: Notice of Intent... between Atlanta, GA and Charlotte, NC, along the Southeast High-Speed Rail Corridor (SEHSR) as designated by the USDOT. The Study is being advanced consistent with the federal High-Speed Intercity...

  11. 77 FR 46685 - In the Matter of: Steven Neal Greenoe, Currently Incarcerated at: Inmate #54450-056, USP Atlanta...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-06

    ... being that of August 12, 2011 (76 FR 50661 (August 16, 2011)), has continued the Regulations in effect...: 8933 Windjammer Drive, Raleigh, NC 27615; Order Denying Export Privileges On January 10, 2012, in the U....S. Penitentiary, P.O. Box 1150160, Atlanta, GA, and 8933 Windjammer Drive, Raleigh, NC 27615,...

  12. The Use of GIS and Remotely Sensed Data in Environmental Public Health Tracking (EPHT): The HELIX-Atlanta Experience

    NASA Technical Reports Server (NTRS)

    Al-Hamdan, Mohammad Z.; Crosson, William L.; Limaye, Ashutosh S.; Estes, Maurice G., Jr.; Watts, Carol; Rickman, Douglas L.; Quattrochi, Dale A.; Qualters, Judith R.; Sinclair, Amber H.; Tolsma, Dennis D.; Adeniyi, Kafayat A.

    2007-01-01

    As part of the National Environmental Public Health Tracking Network (EPHTN), the National Center for Environmental Health (NCEH) at the Centers for Disease Control and Prevention (CDC) is leading a project in collaboration with the NASA Marshall Space Flight Center (NASA/MSFC) called Health and Environment Linked for Information Exchange (HELIX-Atlanta). HELIX-Atlanta's goal is to examine the feasibility of building an integrated electronic health and environmental data network in five counties of metropolitan Atlanta, GA. Under HELIX-Atlanta, pilot projects are being conducted to develop methods to characterize exposure; link health and environmental data; analyze the relationship between health and environmental factors; and communicate findings. There is evidence in the research literature that asthmatic persons are at increased risk of developing asthma exacerbations with exposure to environmental factors, including PM(sub 2.5). Thus, HELIX-Atlanta is focusing on methods for characterizing population exposure to PM(sub 2.5) for the Atlanta metropolitan area that could be used in ongoing surveillance. NASA/MSFC is working with CDC to combine NASA earth science satellite observations related to air quality and environmental monitoring data to model surface estimates of fine particulate matter (PM(sub 2.5)) concentrations in a Geographic Information System (GIS) that can be linked with clinic visits for asthma on the aggregated grid level as well as the individual level at the geographic locations of the patients' residences.

  13. NARSTO EPA SS ATLANTA 1999 CHEM PM MET DATA

    Atmospheric Science Data Center

    2014-04-25

    NARSTO EPA SS ATLANTA 1999 CHEM PM MET DATA Note: The negative sign is ... the longitude in the following data files: NARSTO_EPA_SS_ATLANTA_GAS_GAS_DATA_1_KB_V1.csv and NARSTO_EPA_SS_ATLANTA_MET_MET_DATA_1_KB_V1.csv Project Title:  NARSTO ...

  14. NARSTO EPA SS ATLANTA 1999 UAH MIPS DATA

    Atmospheric Science Data Center

    2014-04-25

    NARSTO EPA SS ATLANTA 1999 UAH MIPS DATA Project Title:  NARSTO ... - Radio Acoustic Sounding System Location:  Atlanta, Georgia Spatial Resolution:  Point Measurements ...   Order Data Guide Documents:  Atlanta UAH MIPS Guide Readme Files:  EPA Sites ...

  15. Health and Environment Linked for Information Exchange in Atlanta (HELIX-Atlanta): A Pilot Tracking System

    NASA Technical Reports Server (NTRS)

    Rickman, Doug; Shire, J.; Qualters, J.; Mitchell, K.; Pollard, S.; Rao, R.; Kajumba, N.; Quattrochi, D.; Estes, M., Jr.; Meyer, P.; Crosson, W.; Limaye, A.; Al-Hamdan, M.; Khan, M.; Bayakly, R.; Staley, F.; Hallisey, E.; Young, J.; Ward, K.; Tolbert, P.; Tolsma, D.; Sinclair, A.; Strickland, M.; Adeniyi, K.; Rainisch, G.

    2009-01-01

    Objectives. To provide an overview of four environmental public health surveillance projects developed by CDC and its partners for the Health and Environment Linked for Information Exchange, Atlanta (HELIX-Atlanta) and to illustrate common issues and challenges encountered in developing an environmental public health tracking system. Methods. HELIX-Atlanta, initiated in October 2003 to develop data linkage and analysis methods that can be used by the National Environmental Public Health Tracking Network (Tracking Network), conducted four projects. We highlight the projects' work, assess attainment of the HELIX-Atlanta goals and discuss three surveillance attributes. Results. Among the major challenges was the complexity of analytic issues which required multidiscipline teams with technical expertise. This expertise and the data resided across multiple organizations. Conclusions:Establishing formal procedures for sharing data, defining data analysis standards and automating analyses, and committing staff with appropriate expertise is needed to support wide implementation of environmental public health tracking.

  16. OVERVIEW OF THE 1999 ATLANTA SUPERSITE PROJECT

    EPA Science Inventory

    This paper presents an overview of the 1999 Atlanta Supersite Project coordinated through the Southern Oxidants Study and the Georgia Institute of Technology (GIT) and funded by the US EPA along with other sponsors who provided in-kind support primarily through existing studies. ...

  17. Playground Hazards in Atlanta Child Care Centers.

    ERIC Educational Resources Information Center

    Sacks, Jeffrey J.; And Others

    1990-01-01

    Examines 71 of the 605 licensed child care centers in Atlanta for playground hazards and school accidents. Finds 684 hazards in 66 centers, including climbing equipment over 6 feet high with inadequate impact-absorbing undersurfacing that had over twice the rate of fall injuries as climbing equipment under 6 feet high. (FMW)

  18. Agricultural Instruction in Secondary Schools: Papers Read at the Third Annual Meeting of the American Association for the Advancement of Agricultural Teaching, Atlanta, Georgia November 12 1912. Bulletin, 1913, No. 14. Whole Number 522

    ERIC Educational Resources Information Center

    United States Bureau of Education, Department of the Interior, 1913

    1913-01-01

    Interest in agricultural education continues to increase. The attempt to teach agriculture is no longer confined to the agricultural college and special agricultural school. Methods of teaching the most important facts and the elementary principles of agriculture are discussed in the meetings of most of our educational associations. There is a…

  19. 78 FR 1742 - Amendment to Class B Airspace; Atlanta, GA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-09

    ... comments on increased fuel consumption for VFR flights if the pilot of these flights chose alternative..., Class B airspace area (77 FR 5429). Interested parties were invited to participate in this rulemaking..., resulting in wasted fuel and increased operating costs as well as causing PDK IFR arrivals to circle...

  20. Magnitudes, nature, and effects of point and nonpoint discharges in the Chattahoochee River basin, Atlanta to West Point Dam, Georgia

    USGS Publications Warehouse

    Stamer, J.K.; Cherry, R.N.; Faye, R.E.; Kleckner, R.L.

    1978-01-01

    On an average annual basis and during the storm period of March 12-15, 1976, nonpoint-source loads for most constituents were larger than point-source loads at the Whitesburg station, located on the Chattahoochee River about 40 miles downstream from Atlanta, GA. Most of the nonpoint-source constituent loads in the Atlanta to Whitesburg reach were from urban areas. Average annual point-source discharges accounted for about 50 percent of the dissolved nitrogen, total nitrogen, and total phosphorus loads and about 70 percent of the dissolved phosphorus loads at Whitesburg. During a low-flow period, June 1-2, 1977, five municipal point-sources contributed 63 percent of the ultimate biochemical oxygen demand, and 97 percent of the ammonium nitrogen loads at the Franklin station, at the upstream end of West Point Lake. Dissolved-oxygen concentrations of 4.1 to 5.0 milligrams per liter occurred in a 22-mile reach of the river downstream from Atlanta due about equally to nitrogenous and carbonaceous oxygen demands. The heat load from two thermoelectric powerplants caused a decrease in dissolved-oxygen concentration of about 0.2 milligrams per liter. Phytoplankton concentrations in West Point Lake, about 70 miles downstream from Atlanta, could exceed three million cells per millimeter during extended low-flow periods in the summer with present point-source phosphorus loads. (Woodard-USGS)

  1. BACKGROUND--ATLANTA, A HANDBOOK FOR REPORTERS COVERING THE DESEGREGATION OF ATLANTA PUBLIC SCHOOLS.

    ERIC Educational Resources Information Center

    HANNER, MRS. PHILIP; AND OTHERS

    A HANDBOOK HAS BEEN PREPARED FOR REPORTERS WHO ARE COVERING THE DESEGREGATION OF ATLANTA PUBLIC SCHOOLS IN ORDER TO INFORM THE PRESS OF THE EFFORTS MADE BY CITIZENS IN THE FIGHT TO KEEP PUBLIC SCHOOLS OPEN. A MAJOR PORTION OF THE GUIDE IS DEVOTED TO A DETAILED, CHRONOLOGICAL ACCOUNT OF THE BACKGROUND PERIOD (1954-61) LEADING TO SCHOOL…

  2. An Examination of Green School Practices in Atlanta Schools

    ERIC Educational Resources Information Center

    Chan, Tak Cheung

    2013-01-01

    The primary goal of this study is to examine green environmental practices exercised in maintaining healthy schools in Atlanta. A forty-item researcher-developed instrument was used to survey 30 randomly sampled schools in the Atlanta area. Five schools particularly strong in green environment implementation were visited to observe their green…

  3. Test-Tampering Found Rampant in Atlanta System

    ERIC Educational Resources Information Center

    Samuels, Christina A.

    2011-01-01

    The author reports on a state investigation into Atlanta's impressive gains on state tests which finds that test-tampering was rampant in the much-praised school system. The report unveiled by the Georgia governor's office states that Atlanta teachers and principals for years methodically altered answer sheets for students taking state tests,…

  4. The Atlanta Public School's Dropout Initiative: A Demonstration Project.

    ERIC Educational Resources Information Center

    Jonas, Edward D., Jr.; Amuleru-Marshall, Nancy

    This project proposes the development and implementation of a model system for collecting, documenting, and reporting to the Atlanta (Georgia) Board of Education information that will indicate the number, ages, and grades of students dropping out of the Atlanta Public School System (APS). Furthermore, this project will demonstrate an effective…

  5. 76 FR 28971 - Atlanta Gas Light Company; Notice of Petition for Rate Approval

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-19

    ... Federal Energy Regulatory Commission Atlanta Gas Light Company; Notice of Petition for Rate Approval Take notice that on May 9, 2011, as supplemented on May 11, 2011, Atlanta Gas Light Company (Atlanta Gas Light... for transportation service. Atlanta Gas Light states the rate election consists of the maximum...

  6. [Classification of an acute pancreatitis: revision by international consensus in 2012 of classification, adopted in Atlanta].

    PubMed

    Kryvoruchko, I A; Kopchak, V M; Usenko, O Iu; Honcharova, N M; Balaka, S M; Teslenko, S M; Andreieshchev, S A

    2014-09-01

    In 1992 on symposium in Atlanta the general classification of an acute pancreatitis, adopted by world medical society for practical application, was proposed. Due to results of multiple investigations there were enhanced the data about an acute pancreatitis pathophysiology, the organs insufficiency, and improvement of the noninvasive and invasive methods of visualization and treatment, what caused necessity to revise the classification. Web-consultations were conducted in 2007 yr to guarantee a wide participation of pancreatologists. After first meeting the working group have directed the document project to 11 national and international associations of pancreatologists. In 2012 yr the definite conclusions, concerning consensus, were published.

  7. Evaluation of a Pilot Surveillance System: Health and Environment Linked for Information Exchange in Atlanta (HELIX-Atlanta)

    NASA Technical Reports Server (NTRS)

    Meyer, P.; Shire, J.; Qualters, Judy; Daley, Randolph; Fiero, Leslie Todorov; Autry, Andy; Avchen, Rachel; Stock, Allison; Correa, Adolofo; Siffel, Csaba; Devine, Owen; Gotway, Carol; Crawford; Mitchell, Ken; Pollard, Solomon; Rao, Ravi; Kajumba, Ntale; Rickman, Doug; Quattrochi, Dale; Estes, Maury; Meyer, Paul; Crosson, Bill; Limaye, Ashutosh; Al-Hamdan, Mohammad; Khan, Maudood

    2007-01-01

    CDC and its partners established the Health and Environment Linked for Information Exchange, Atlanta (HELIX-Atlanta) demonstration project, to develop linking and analysis methods that could be used by the National Environmental Public Health Tracking (EPHT) Network. Initiated in October 2003, the Metropolitan Atlanta-based collaborative conducted four projects: asthma and particulate air pollution, birth defects and ozone and particulate air pollution, childhood leukemia and traffic emissions, and children's blood lead testing and neighborhood risk factors for lead poisoning. This report provides an overview of the HELIX-Atlanta projects' goals, methods and outcomes. We discuss priority attributes and common issues and challenges and offer recommendations for implementation of the nascent national environmental public health tracking network.

  8. The Metro Atlanta Solar System: A Southern Slice of the Sky

    NASA Astrophysics Data System (ADS)

    De Pree, Christopher G.

    2010-01-01

    The Metro Atlanta Solar System (MASS) is a scale model solar system centered at the Bradley Observatory plaza on the campus of Agnes Scott College, a liberal arts women's college located in Decatur, GA. The MASS model was dedicated on September 11, 2009 in celebration of the International Year of Astronomy (IYA). One of the planets (Uranus) was installed at Hartsfield Jackson International Airport in May 2009 as part of the From Earth to the Universe (FETTU) exhibit that will be at the airport through the end of January 2010. MASS places scaled images of the planets at locations throughout the city, along their orbits at distances scaled to the size of a 30 foot diameter Sun (the observing plaza) located at Agnes Scott College. The planetary images are those from the airport FETTU exhibition, so the model serves as a way to connect the entire city of Atlanta to the airport images. In this model, 1 AU = 1 km. We discuss the planning, implementation and future uses of this model.

  9. Meetings

    NASA Astrophysics Data System (ADS)

    As the first Meeting Chairman for the Spring and Fall meetings, Martin Walt has achieved notable success in realizing the many goals set forth by the Union for its annual meetings. Under his guidance, the Meeting Program Committee has been able to reduce the number of conflicting sessions and provide for the presentation of well-organized and effectively displayed poster sessions. The early planning of Union sessions and the introduction of ‘mini-frontiers,’ along with careful scheduling, has provided an increased opportunity for participation. A record high of 2785 registrants was recorded during the 1981 Fall Meeting, topping very slightly the old record of 2775 for the 1974 Spring Meeting.

  10. Airport Surface Movement Technologies: Atlanta Demonstrations Overview

    NASA Technical Reports Server (NTRS)

    Jones, Denise R.; Young, Steven D.

    1997-01-01

    A flight demonstration was conducted in August 1997 at the Hartsfield Atlanta (ATL) International Airport as part of low visibility landing and surface operations (LVLASO) research activities. This research was aimed at investigating technology to improve the safety and efficiency of aircraft movements on the surface during the operational phases of roll-out, turnoff, and taxi in any weather condition down to a runway visual range of 300 feet. The system tested at ATL was composed of airborne and ground-based components that were integrated to provide both the flight crew and controllers with supplemental information to enable safe, expedient surface operations. Experimental displays were installed on a Boeing 757-200 research aircraft in both headup and head-down formats. On the ground, an integrated system maintained surveillance of the airport surface and a controller interface provided routing and control instructions. While at ATL, the research aircraft performed a series of flight and taxi operations to show the validity of the operational concept at a major airport facility, to validate simulation findings, and to assess each of the individual technologies performance in an airport environment. The concept was demonstrated to over 100 visitors from the Federal Aviation Administration (FAA) and the aviation community. This paper gives an overview of the LVLASO system and ATL test activities.

  11. Meteor wind results from Atlanta, USA, and Ramey, Puerto Rico

    NASA Technical Reports Server (NTRS)

    Roper, R. G.

    1984-01-01

    Results obtained using the French (CNET) meteor wind radar at Ramey, Puerto Rico, and the Georgia Tech radio meteor wind facility in Atlanta, U.S.A., are presented and compared. Prevailing wind, diurnal, and semidiurnal wind amplitudes are considerably larger over Ramey than over Atlanta, but the mean zonal circulation over Atlanta is more characteristic of the equatorial circulation than winds measured by stations at higher midlatitudes. The value of continuous observations, with a height resolution of + or - 2 km, is emphasized, as is the need for the application of several techniques, groundbased, in situ and satellite, if projects such as the MAP GLOBMET are to succeed in delineating the global meteorology of the mesopause.

  12. The State of Youth at Risk and the Juvenile Justice System: Prevention and Intervention. Hearing on Support for State Law Enforcement Efforts and for State Juvenile Justice Systems To Help Address the Wave of Violent Crimes among Youthful Offenders before the Subcommittee on Juvenile Justice of the Committee on the Judiciary, United States Senate, One Hundred Second Congress, Second Session (Atlanta, GA, October 21, 1992).

    ERIC Educational Resources Information Center

    Congress of the U.S., Washington, DC. Senate Committee on the Judiciary.

    This document presents witness testimonies and prepared statements from a Senate hearing held in Atlanta, Georgia to examine the problem of crime among youth and to discuss the reauthorization of the Juvenile Justice and Delinquency Prevention Act of 1974. In his opening statement, Senator Fowler notes that the reauthorization puts greater…

  13. 40 CFR 81.45 - Metropolitan Atlanta Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 17 2011-07-01 2011-07-01 false Metropolitan Atlanta Intrastate Air... Air Quality Control Regions § 81.45 Metropolitan Atlanta Intrastate Air Quality Control Region. The Metropolitan Atlanta Intrastate Air Quality Control Region (Georgia) has been revised to consist of...

  14. 40 CFR 81.45 - Metropolitan Atlanta Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 18 2014-07-01 2014-07-01 false Metropolitan Atlanta Intrastate Air... Air Quality Control Regions § 81.45 Metropolitan Atlanta Intrastate Air Quality Control Region. The Metropolitan Atlanta Intrastate Air Quality Control Region (Georgia) has been revised to consist of...

  15. 40 CFR 81.45 - Metropolitan Atlanta Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 18 2012-07-01 2012-07-01 false Metropolitan Atlanta Intrastate Air... Air Quality Control Regions § 81.45 Metropolitan Atlanta Intrastate Air Quality Control Region. The Metropolitan Atlanta Intrastate Air Quality Control Region (Georgia) has been revised to consist of...

  16. 40 CFR 81.45 - Metropolitan Atlanta Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 18 2013-07-01 2013-07-01 false Metropolitan Atlanta Intrastate Air... Air Quality Control Regions § 81.45 Metropolitan Atlanta Intrastate Air Quality Control Region. The Metropolitan Atlanta Intrastate Air Quality Control Region (Georgia) has been revised to consist of...

  17. 40 CFR 81.45 - Metropolitan Atlanta Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 17 2010-07-01 2010-07-01 false Metropolitan Atlanta Intrastate Air... Air Quality Control Regions § 81.45 Metropolitan Atlanta Intrastate Air Quality Control Region. The Metropolitan Atlanta Intrastate Air Quality Control Region (Georgia) has been revised to consist of...

  18. Student Financial Aid Issues Hearing Report (Atlanta, Georgia,

    ERIC Educational Resources Information Center

    Advisory Committee on Student Financial Assistance, Washington, DC.

    This paper summarizes results of a hearing by the Advisory Committee on Student Financial Assistance in Atlanta, Georgia, on the delivery and disposition of higher education student financial assistance funds. Seventeen individuals offered testimony. They included representatives of guarantee agencies, the lending community, the financial aid…

  19. Spatial analysis of ozone in Atlanta: Regulatory and epidemiologic implications

    SciTech Connect

    Butler, A.J.; Mulholland, J.A.; Wilkinson, J.G.; Russell, A.G.; Tolbert, P.E.

    1998-12-31

    Relationships between ambient levels of selected air pollutants and pediatric asthma exacerbation in Atlanta were studied retrospectively. As a part of this study, spatial distributions of ambient ozone concentrations in the twenty-county Atlanta metropolitan area during the summers of 1993, 1994 and 1995 were estimated and assessed. A universal kriging procedure was used for spatial interpolation of aerometric monitoring station data. In this paper, the spatial distributions of ozone are described, and regulatory and epidemiologic implications are discussed. For the study period, the Atlanta ozone nonattainment area based on the one-hour, exceedance-based standard of 0.12 ppm is estimated to expand from 56 percent of the Atlanta MSA by area and 71 percent by population to 88 percent by area and 96 percent by population under the new eight-hour, concentration-based standard of 0.08 ppm. Regarding asthma exacerbation, a 4 percent increase in pediatric asthma emergency room presentation rate per 20 ppb increase in ambient ozone concentration was observed (p-value = 0.001). Ambient ozone level represents a general indicator of air quality due to its correlation with other pollutants. The use of spatially-resolved ozone estimates in the epidemiologic analysis demonstrates the need to control confounding by demographic covariates.

  20. Changing the Odds: The Race for Results in Atlanta

    ERIC Educational Resources Information Center

    Williams, Janelle; Torian, Sarah

    2015-01-01

    Casey has invested in several southwest Atlanta communities for more than 10 years. This report explores how race and community of residence continue to create barriers that keep the city's kids, particularly those of color, from reaching their full potential. The report highlights three key areas that support or thwart children's healthy…

  1. Political Socialization in an International City: The Case of Atlanta.

    ERIC Educational Resources Information Center

    Masters, Paul E., Jr.

    1984-01-01

    Original survey data dealing with the attitudes about international relations of secondary students in the metropolitan Atlanta, Georgia, area are analyzed. Student opinions were measured in three areas: (1) international interest, knowledge, and information sources; (2) international conflict and the balance of power; and (3) international…

  2. A Time for Silence: Booker T. Washington in Atlanta.

    ERIC Educational Resources Information Center

    Heath, Robert L.

    1978-01-01

    Discusses the rhetoric of silence as an alternative to participation in a discussion of social issues, particularly when participation confirms the efforts of those who seek social control. Concludes that Booker T. Washington should have employed the strategy of silence when invited to address an exposition in Atlanta in 1895. (JMF)

  3. What Can We Learn from the Atlanta Cheating Scandal?

    ERIC Educational Resources Information Center

    Saultz, Andrew; Murphy, Kristin M.; Aronson, Brittany

    2016-01-01

    In April 2015, 11 educators were convicted for their roles in the cheating scandal in the Atlanta Public Schools. The authors examine the lessons that teachers, administrators, and policy makers can learn from the cheating scandal: Teachers and school leaders were not adequately prepared to navigate the school district's environment; there were…

  4. OBJECTIVES, DESIGN, AND PRELIMINARY RESULTS FROM THE ATLANTA SUPERSITE PROJECT

    EPA Science Inventory

    The Atlanta Supersites project is the first of two Supersites projects to be established during Phase I of EPA's Supersites Program; Phase II is being established through a Request for Assistance. The other initial project is in Fresno, California. The Supersite Program is part o...

  5. Environmental Public Health Tracking: Health and Environment Linked for Information Exchange-Atlanta (HEXIX-Atlanta: A cooperative Program Between CDC and NASA for Development of an Environmental Public Health Tracking Network in the Atlanta Metropolitan Area

    NASA Technical Reports Server (NTRS)

    Quattrochi, Dale A.; Niskar, Amanda Sue

    2005-01-01

    The Centers for Disease Control and Prevention (CDC) is coordinating HELIX- Atlanta to provide information regarding the five-county Metropolitan Atlanta Area (Clayton, Cobb, DeKalb, Fulton, and Gwinett) via a network of integrated environmental monitoring and public health data systems so that all sectors can take action to prevent and control environmentally related health effects. The HELIX-Atlanta Network is a tool to access interoperable information systems with optional information technology linkage functionality driven by scientific rationale. HELIX-Atlanta is a collaborative effort with local, state, federal, and academic partners, including the NASA Marshall Space Flight Center. The HELIX-Atlanta Partners identified the following HELIX-Atlanta initial focus areas: childhood lead poisoning, short-latency cancers, developmental disabilities, birth defects, vital records, respiratory health, age of housing, remote sensing data, and environmental monitoring, HELIX-Atlanta Partners identified and evaluated information systems containing information on the above focus areas. The information system evaluations resulted in recommendations for what resources would be needed to interoperate selected information systems in compliance with the CDC Public Health Information Network (PHIN). This presentation will discuss the collaborative process of building a network that links health and environment data for information exchange, including NASA remote sensing data, for use in HELIX-Atlanta.

  6. Project ATLANTA (ATlanta Land-use ANalysis: Temperature and Air quality): A Study of how the Urban Landscape Affects Meteorology and Air Quality Through Time

    NASA Technical Reports Server (NTRS)

    Quattrochi, Dale A.; Luvall, Jeffrey C.; Estes, Maurice G.; Lo, C. P.; Kidder, Stanley Q.; Hafner, Jan; Taha, Haider; Bornstein, Robert D.; Gillies, Robert R.; Gallo, Kevin P.

    1998-01-01

    It is our intent through this investigation to help facilitate measures that can be Project ATLANTA (ATlanta Land-use ANalysis: applied to mitigate climatological or air quality Temperature and Air-quality) is a NASA Earth degradation, or to design alternate measures to sustain Observing System (EOS) Interdisciplinary Science or improve the overall urban environment in the future. investigation that seeks to observe, measure, model, and analyze how the rapid growth of the Atlanta. The primary objectives for this research effort are: 1) To In the last half of the 20th century, Atlanta, investigate and model the relationship between Atlanta Georgia has risen as the premier commercial, urban growth, land cover change, and the development industrial, and transportation urban area of the of the urban heat island phenomenon through time at southeastern United States. The rapid growth of the nested spatial scales from local to regional; 2) To Atlanta area, particularly within the last 25 years, has investigate and model the relationship between Atlanta made Atlanta one of the fastest growing metropolitan urban growth and land cover change on air quality areas in the United States. The population of the through time at nested spatial scales from local to Atlanta metropolitan area increased 27% between 1970 regional; and 3) To model the overall effects of urban and 1980, and 33% between 1980-1990 (Research development on surface energy budget characteristics Atlanta, Inc., 1993). Concomitant with this high rate of across the Atlanta urban landscape through time at population growth, has been an explosive growth in nested spatial scales from local to regional. Our key retail, industrial, commercial, and transportation goal is to derive a better scientific understanding of how services within the Atlanta region. This has resulted in land cover changes associated with urbanization in the tremendous land cover change dynamics within the Atlanta area, principally in transforming

  7. Imaging lexicon for acute pancreatitis: 2012 Atlanta Classification revisited.

    PubMed

    Sureka, Binit; Bansal, Kalpana; Patidar, Yashwant; Arora, Ankur

    2016-02-01

    The original 1992 Atlanta Classification System for acute pancreatitis was revised in 2012 by the Atlanta Working Group, assisted by various national and international societies, through web-based consensus. This revised classification identifies two phases of acute pancreatitis: early and late. Acute pancreatitis can be either oedematous interstitial pancreatitis or necrotizing pancreatitis. Severity of the disease is categorized into three levels: mild, moderately severe and severe, depending upon organ failure and local/systemic complications. According to the type of pancreatitis, collections are further divided into acute peripancreatic fluid collection, pseudocyst, acute necrotic collection, and walled-off necrosis. Insight into the revised terminology is essential for accurate communication of imaging findings. In this review article, we will summarize the updated nomenclature and illustrate corresponding imaging findings using examples.

  8. Climate change adaptation through urban heat management in Atlanta, Georgia.

    PubMed

    Stone, Brian; Vargo, Jason; Liu, Peng; Hu, Yongtao; Russell, Armistead

    2013-07-16

    This study explores the potential effectiveness of metropolitan land cover change as a climate change adaptation strategy for managing rising temperatures in a large and rapidly warming metropolitan region of the United States. Through the integration of a mesoscale meteorological model with estimated land cover data for the Atlanta, Georgia region in 2010, this study quantifies the influence of extensive land cover change at the periphery of a large metropolitan region on temperature within the city center. The first study to directly model a metropolitan scale heat transfer mechanism, we find both enhanced tree canopy and impervious cover in the suburban zones of the Atlanta region to produce statistically significant cooling and warming effects in the urban core. Based on these findings, we conclude that urban heat island management both within and beyond the central developed core of large cities may provide an effective climate change adaptation strategy for large metropolitan regions.

  9. Operation Heli-STAR - Atlanta Communications Experiment (ACE). Volume 9

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Operation Heli-STAR (Helicopter Short-Haul Transportation and Aviation Research) was established and operated in Atlanta, Georgia, during the period of the 1996 Centennial Olympic Games. Heli-STAR had three major thrusts: (1) the establishment and operation of a helicopter-based cargo transportation system, (2) the management of low-altitude air traffic in the airspace of an urban area, and (3) the collection and analysis of research and development data associated with items 1 and 2. Heli-STAR was a cooperative industry/government program that included parcel package shippers and couriers in the Atlanta area, the helicopter industry, aviation electronics manufacturers, the Federal Aviation Administration (FAA), the National Aeronautics and Space Administration (NASA), and support contractors. Several detailed reports have been produced as a result of Operation Heli-STAR. These include four reports on acoustic measurements and associated analyses, and reports on the Heli-STAR tracking data including the data processing and retrieval system, the Heli-STAR cargo simulation, and the community response system. In addition, NASA's Advanced General Aviation Transport Experiments (AGATE) program has produced a report describing the Atlanta Communications Experiment (ACE) which produced the avionics and ground equipment using automatic dependent surveillance-broadcast (ADS-B) technology. This latter report is restricted to organizations belonging to NASA's AGATE industry consortium. A complete list of these reports is shown on the following page.

  10. Revised Atlanta Classification for Acute Pancreatitis: A Pictorial Essay.

    PubMed

    Foster, Bryan R; Jensen, Kyle K; Bakis, Gene; Shaaban, Akram M; Coakley, Fergus V

    2016-01-01

    The 2012 revised Atlanta classification is an update of the original 1992 Atlanta classification, a standardized clinical and radiologic nomenclature for acute pancreatitis and associated complications based on research advances made over the past 2 decades. Acute pancreatitis is now divided into two distinct subtypes, necrotizing pancreatitis and interstitial edematous pancreatitis (IEP), based on the presence or absence of necrosis, respectively. The revised classification system also updates confusing and sometimes inaccurate terminology that was previously used to describe pancreatic and peripancreatic collections. As such, use of the terms acute pseudocyst and pancreatic abscess is now discouraged. Instead, four distinct collection subtypes are identified on the basis of the presence of pancreatic necrosis and time elapsed since the onset of pancreatitis. Acute peripancreatic fluid collections (APFCs) and pseudocysts occur in IEP and contain fluid only. Acute necrotic collections (ANCs) and walled-off necrosis (WON) occur only in patients with necrotizing pancreatitis and contain variable amounts of fluid and necrotic debris. APFCs and ANCs occur within 4 weeks of disease onset. After this time, APFCs or ANCs may either resolve or persist, developing a mature wall to become a pseudocyst or a WON, respectively. Any collection subtype may become infected and manifest as internal gas, though this occurs most commonly in necrotic collections. In this review, the authors present a practical image-rich guide to the revised Atlanta classification system, with the goal of fostering implementation of the revised system into radiology practice, thereby facilitating accurate communication among clinicians and reinforcing the radiologist's role as a key member of a multidisciplinary team in treating patients with acute pancreatitis. (©)RSNA, 2016.

  11. 76 FR 66713 - Atlanta Gas Light Company; Notice of Compliance Filing

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-27

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Atlanta Gas Light Company; Notice of Compliance Filing Take notice that on October 19, 2011, Atlanta Gas Light Company filed a revised Statement of Operating Conditions...

  12. Falsification, Annual Targets, and Errant Leadership: Media Portrayal of the Atlanta Test-Cheating Scandal

    ERIC Educational Resources Information Center

    Freeman, Eric

    2015-01-01

    This analysis of the Atlanta test-cheating scandal differs markedly from the version reported in the press. Using discourse analysis, I examined over 50 articles published in the "Atlanta Journal-Constitution" ("AJC"), the hometown newspaper at the center of the investigation. Because newspapers are a primary source of…

  13. The Social Studies Curriculum in Atlanta Public Schools during the Desegregation Era

    ERIC Educational Resources Information Center

    Bohan, Chara Haeussler; Randolph, Patricia

    2009-01-01

    This historical investigation explores how teachers, students, and education officials viewed the social studies curriculum in the local context of Atlanta, and the broader state of Georgia, during the post-Civil Rights era, when integration was a court-ordered reality in the public schools. During the desegregation era, Atlanta schools were led…

  14. AN OVERVIEW OF THE OBJECTIVES AND DESIGN OF THE '99 ATLANTA SUPERSITE EXPERIMENT

    EPA Science Inventory

    During the Summer of 1999, a 4-week intensive field campaign was conducted at a site on Jefferson Street in Midtown Atlanta. The campaign, the 1999 Atlanta Supersites Experiment, was carried out under the direction of the Southern Oxidants Study and represented the first of U....

  15. A New Definition in Atlanta: Q&A with Beverly Hall

    ERIC Educational Resources Information Center

    Crow, Tracy

    2010-01-01

    Beverly Hall has been superintendent of Atlanta Public Schools since 1999. Before coming to Atlanta, Hall was state district superintendent of Newark Public Schools, deputy chancellor for instruction of New York City Public Schools, superintendent of Community School District 27 in New York City, and a principal in Brooklyn. Hall chairs Harvard…

  16. 78 FR 32135 - Approval and Promulgation of Implementation Plans; Atlanta, Georgia 1997 8-Hour Ozone...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-29

    ... the 1-hour ozone NAAQS for the Atlanta Area on April 26, 1999. See 64 FR 20196. \\3\\ The 13-County... Area's original attainment date was June 15, 2007. See 69 FR 23951, April 30, 2004. The Atlanta Area.... See 73 FR 12013, March 6, 2008. When an area is reclassified, a new attainment date for...

  17. Why, Where, and How to Infuse the Atlanta Sociological Laboratory into the Sociology Curriculum

    ERIC Educational Resources Information Center

    Wright, Earl, II

    2012-01-01

    The Atlanta Sociological Laboratory is the moniker bestowed on scholars engaged in sociological research at Atlanta University between 1895 and 1924. Under the leadership of W. E. B. Du Bois, 1897-1914, this school made substantive yet marginalized contributions to the discipline. Its accomplishments include, but are not limited to, its…

  18. Healthy beginnings: a system of care for children in Atlanta.

    PubMed

    Chao, Ryan; Bertonaschi, Susan; Gazmararian, Julie

    2014-12-01

    For more than a decade the Annie E. Casey Foundation's Atlanta Civic Site has invested in a comprehensive community change strategy in five neighborhoods near downtown Atlanta. The foundation pursues a three-prong strategy focused on improving educational outcomes for children, encouraging family economic success for adults, and positively transforming the community's physical environment. The foundation recently integrated a focus on health into its community and family strengthening strategies. In this article we review the foundation's Healthy Beginnings System of Care. Healthy Beginnings seeks to prevent or reduce health disparities through a community-based, coordinated care approach based in a high-quality early learning center. An initial evaluation found that in 2013 the program exceeded all of its performance requirements for the 279 enrolled children. Ninety-seven percent of the children had health insurance, 92 percent were up to date with immunizations, and 98 percent were current with developmental screenings. By building upon the partnerships formed through the foundation's community change effort, Healthy Beginnings has dramatically increased neighborhood children's access to health care and forms the basis for a cost-effective approach that can be replicated in other communities.

  19. Race, socioeconomic status, and domestic homicide, Atlanta, 1971-72.

    PubMed Central

    Centerwall, B S

    1984-01-01

    It has been assumed that, under comparable socioeconomic conditions, Blacks are more likely than Whites to commit violent acts. To test this assumption, 222 intra-racial domestic homicides (186 Black and 36 White victims) committed in Atlanta, 1971-1972, were subjected to analysis. A domestic homicide was defined as a criminal homicide committed in a residence by a relative or acquaintance of the victim. When Black and White populations were unmatched, the relative risk of intra-racial domestic homicide in Black populations was 5.8 (95 per cent C.I.: 4.3-8.0). When Black and White populations were matched for rates of household crowding, the relative risk of intra-racial domestic homicide in Black populations was no longer significantly elevated (relative risk = 1.2; 95 per cent C.I.: 0.7-2.0). Using rates of household crowding as an index of socioeconomic status, Atlanta Blacks were no more likely to commit domestic homicide than were Whites in comparable socioeconomic circumstances. Further research is needed to determine whether household crowding per se is a risk factor for domestic homicide, independent of socioeconomic status. PMID:6742272

  20. Solar hot water system installed at Day's Lodge, Atlanta, Georgia

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The solar energy hot water system installed in the Days Inns of America, Inc., Atlanta, Georgia is described. This system provides for 81 percent of the total hot water demand. There are two separate systems, each serving one building of the lodge (total of 65 suites). The entire system contains only potable city water. The 1024 square feet of Grumman Sunstream Model 332 liquid flat plate collectors and the outside piping drain whenever the collector plates approach freezing or when power is interrupted. Solar heated water from the two above ground cement lined steel tanks (1000 gallon tank) is drawn into the electric Domestic Hot Water (DHW) tanks as hot water is drawn. Electric resistance units in the DHW tanks top off the solar heated water, if needed, to reach thermostat setting.

  1. Building America Case Study: Ground Source Heat Pump Research, TaC Studios Residence, Atlanta, Georigia (Fact Sheet)

    SciTech Connect

    Not Available

    2014-09-01

    As part of the NAHB Research Center Industry Partnership, Southface partnered with TaC Studios, an Atlanta based architecture firm specializing in residential and light commercial design, on the construction of a new test home in Atlanta, GA in the mixed-humid climate. This home serves as a residence and home office for the firm's owners, as well as a demonstration of their design approach to potential and current clients. Southface believes the home demonstrates current best practices for the mixed-humid climate, including a building envelope featuring advanced air sealing details and low density spray foam insulation, glazing that exceeds ENERGY STAR requirements, and a high performance heating and cooling system. Construction quality and execution was a high priority for TaC Studios and was ensured by a third party review process. Post construction testing showed that the project met stated goals for envelope performance, an air infiltration rate of 2.15 ACH50. The homeowner's wished to further validate whole house energy savings through the project's involvement with Building America and this long-term monitoring effort. As a Building America test home, this home was evaluated to detail whole house energy use, end use loads, and the efficiency and operation of the ground source heat pump and associated systems. Given that the home includes many non-typical end use loads including a home office, pool, landscape water feature, and other luxury features not accounted for in Building America modeling tools, these end uses were separately monitored to determine their impact on overall energy consumption.

  2. Association between severity and the determinant-based classification, Atlanta 2012 and Atlanta 1992, in acute pancreatitis: a clinical retrospective study.

    PubMed

    Chen, Yuhui; Ke, Lu; Tong, Zhihui; Li, Weiqin; Li, Jieshou

    2015-04-01

    Recently, the determinant-based classification (DBC) and the Atlanta 2012 have been proposed to provide a basis for study and treatment of acute pancreatitis (AP). The present study aimed to evaluate the association between severity and the DBC, the Atlanta 2012 and the Atlanta 1992, in AP. Patients admitted to our center with AP from January 2007 to July 2013 were reviewed retrospectively. Patients were assigned to severity categories for all the 3 classification systems. The primary outcomes include long-term clinical prognosis (mortality and length-of-hospital stay), major complications (intraabdominal hemorrhage, multiple-organ dysfunction, single organ failure [OF], and sepsis) and clinical interventions (surgical drainage, continuous renal replace therapy [CRRT] lasting time, and mechanical ventilation [MV] lasting time). The classification systems were validated and compared in terms of these abovementioned primary outcomes. A total of 395 patients were enrolled in this retrospective study with an overall 8.86% in-hospital mortality. Intraabdominal hemorrhage was present in 27 (6.84%) of the patients, multiple-organ dysfunction in 73(18.48%), single OF in 67 (16.96%), and sepsis in 73(18.48%). For each classification system, different categories regarding severity were associated with statistically different clinical mortality, major complications, and clinical interventions (P < 0.05). However, the Atlanta 2012 and the DBC performed better than the Atlanta 1992, and they were comparable in predicting mortality (area under curve [AUC] 0.899 and 0.955 vs 0.585, P < 0.05); intraabdominal hemorrhage (AUC 0.930 and 0.961 vs 0.583, P < 0.05), multiple-organ dysfunction (AUC 0.858 and 0.881 vs 0.595, P < 0.05), sepsis (AUC 0.826 and 0.879 vs 0.590, P < 0.05), and surgical drainage (AUC 0.900 and 0.847 vs 0.606, P < 0.05). For continuous variables, the Atlanta 2012 and the DBC were also better than the Atlanta 1992, and they were similar in

  3. Risk Factors for HIV Transmission and Barriers to HIV Disclosure: Metropolitan Atlanta Youth Perspectives.

    PubMed

    Camacho-Gonzalez, Andres F; Wallins, Amy; Toledo, Lauren; Murray, Ashley; Gaul, Zaneta; Sutton, Madeline Y; Gillespie, Scott; Leong, Traci; Graves, Chanda; Chakraborty, Rana

    2016-01-01

    Youth carry the highest incidence of HIV infection in the United States. Understanding adolescent and young adult (AYA) perspectives on HIV transmission risk is important for targeted HIV prevention. We conducted a mixed methods study with HIV-infected and uninfected youth, ages 18-24 years, from Atlanta, GA. We provided self-administered surveys to HIV-infected and HIV-uninfected AYAs to identify risk factors for HIV acquisition. By means of computer-assisted thematic analyses, we examined transcribed focus group responses on HIV education, contributors to HIV transmission, and pre-sex HIV status disclosure. The 68 participants had the following characteristics: mean age 21.5 years (standard deviation: 1.8 years), 85% male, 90% black, 68% HIV-infected. HIV risk behaviors included the perception of condomless sex (Likert scale mean: 8.0) and transactional sex (88% of participants); no differences were noted by HIV status. Qualitative analyses revealed two main themes: (1) HIV risk factors among AYAs, and (2) barriers to discussing HIV status before sex. Participants felt the use of social media, need for immediate gratification, and lack of concern about HIV disease were risk factors for AYAs. Discussing HIV status with sex partners was uncommon. Key reasons included: fear of rejection, lack of confidentiality, discussion was unnecessary in temporary relationships, and disclosure negatively affecting the mood. HIV prevention strategies for AYAs should include improving condom use frequency and HIV disclosure skills, responsible utilization of social media, and education addressing HIV prevention including the risks of transactional sex.

  4. Risk Factors for HIV Transmission and Barriers to HIV Disclosure: Metropolitan Atlanta Youth Perspectives.

    PubMed

    Camacho-Gonzalez, Andres F; Wallins, Amy; Toledo, Lauren; Murray, Ashley; Gaul, Zaneta; Sutton, Madeline Y; Gillespie, Scott; Leong, Traci; Graves, Chanda; Chakraborty, Rana

    2016-01-01

    Youth carry the highest incidence of HIV infection in the United States. Understanding adolescent and young adult (AYA) perspectives on HIV transmission risk is important for targeted HIV prevention. We conducted a mixed methods study with HIV-infected and uninfected youth, ages 18-24 years, from Atlanta, GA. We provided self-administered surveys to HIV-infected and HIV-uninfected AYAs to identify risk factors for HIV acquisition. By means of computer-assisted thematic analyses, we examined transcribed focus group responses on HIV education, contributors to HIV transmission, and pre-sex HIV status disclosure. The 68 participants had the following characteristics: mean age 21.5 years (standard deviation: 1.8 years), 85% male, 90% black, 68% HIV-infected. HIV risk behaviors included the perception of condomless sex (Likert scale mean: 8.0) and transactional sex (88% of participants); no differences were noted by HIV status. Qualitative analyses revealed two main themes: (1) HIV risk factors among AYAs, and (2) barriers to discussing HIV status before sex. Participants felt the use of social media, need for immediate gratification, and lack of concern about HIV disease were risk factors for AYAs. Discussing HIV status with sex partners was uncommon. Key reasons included: fear of rejection, lack of confidentiality, discussion was unnecessary in temporary relationships, and disclosure negatively affecting the mood. HIV prevention strategies for AYAs should include improving condom use frequency and HIV disclosure skills, responsible utilization of social media, and education addressing HIV prevention including the risks of transactional sex. PMID:26588663

  5. 78 FR 50373 - Agenda and Notice of Public Meeting of the Kentucky Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-19

    ... From the Federal Register Online via the Government Publishing Office COMMISSION ON CIVIL RIGHTS... to the provisions of the rules and regulations of the U.S. Commission on Civil Rights (Commission... Civil Rights, 61 Forsyth St. SW., Suite 16T126, Atlanta, GA 30303. Persons wishing to email...

  6. 75 FR 47770 - Agenda and Notice of Public Meeting of the Tennessee Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-09

    ... From the Federal Register Online via the Government Publishing Office COMMISSION ON CIVIL RIGHTS... to the provisions of the rules and regulations of the U.S. Commission on Civil Rights (Commission.... Commission on Civil Rights, 61 Forsyth St., SW., Suite 16T126, Atlanta, GA, 30303. They may also be faxed...

  7. 75 FR 22737 - Agenda and Notice of Public Meeting of the Kentucky Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-30

    ... From the Federal Register Online via the Government Publishing Office COMMISSION ON CIVIL RIGHTS... to the provisions of the rules and regulations of the U.S. Commission on Civil Rights (Commission..., U.S. Commission on Civil Rights, 61 Forsyth Street, Suite 18T40, Atlanta, GA 30301. Persons...

  8. 77 FR 24683 - Agenda and Notice of Public Meeting of the Florida Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-25

    ... From the Federal Register Online via the Government Publishing Office COMMISSION ON CIVIL RIGHTS... the provisions of the rules and regulations of the U.S. Commission on Civil Rights (Commission) and..., U.S. Commission on Civil Rights, 61 Forsyth St., SW., Suite 16T126, Atlanta, GA, 30303. They...

  9. The Atlanta FICSIT study: two exercise interventions to reduce frailty in elders.

    PubMed

    Wolf, S L; Kutner, N G; Green, R C; McNeely, E

    1993-03-01

    This study examines the effect of two different exercise approaches on balance and frailty measures among more than 200 community-dwelling individuals greater than 70 years of age. Exercises are provided for 15 weekly sessions on an individual basis for participants randomly assigned to a Balance Training group. Training consists of center-of-mass feedback displayed on a motor under static conditions, or, in later sessions, as the floor surface is moved, with eyes open or closed. This high technology interface provides instantaneous information about displacement of body weight in space so that balance can be enhanced. An alternative procedure is comparatively simple and requires little expense or space. Tai Chi Quan was originally developed as a martial arts form but has been used for centuries in China as an exercise among elderly citizens. Participants randomly assigned to this intervention meet twice weekly for 15 weeks to learn a condensation of 108 Tai Chi forms into 10 that emphasize movement components often restricted or absent with aging. A third group serves as a control for exercise interventions by meeting weekly for 15 sessions to discuss topics of interest such as memory loss, drug management, and nutrition. All subjects are screened prior to assignment, and a host of physical, behavioral, and functional measures are assessed before and after the intervention as well as 4 months later. Measurements unique to the Atlanta site include: balance with eyes closed, programmed force-distribution changes when stance is perturbed, cardiovascular assessments, WAIS, Affects Balance Scale, and a survey of home environment.

  10. Social Network Composition and Sexual Risk-Taking among Gay and Bisexual Men in Atlanta, GA

    PubMed Central

    Finneran, Catherine; Stephenson, Rob

    2014-01-01

    Social network composition is known to effect patterns of reported sexual risk-taking among men who have sex with men (MSM); however, consensus as to the directionality and size of these effects is lacking. We examined the relationships between novel aspects of social network composition and sexual risk-taking using a cross-sectional survey of 870 MSM. Social network composition was found to have mixed effects on reported sexual risk-taking: reporting proportionally more LGB-identified friends and reporting friends who were on average significantly older than the respondent were both associated with reporting increased sexual risk, while reporting proportionally more LGB-identified friends in relationships and reporting a social network proportionally more aware of the respondent’s homosexuality/bisexuality were both associated with reporting decreased sexual risk. The support structures created by differing social network compositions – and particularly the presence of LGB couples -- may be a potential area for targeting sexual risk-reduction interventions for MSM. PMID:23904146

  11. DOE ZERH Case Study: Heirloom Design Build, Euclid Avenue, Atlanta, GA

    SciTech Connect

    none,

    2015-09-01

    Case study of a DOE 2015 Housing Innovation Award winning custom home in the mixed-humid climate that got a HERS 50 without PV, with 2x6 16” on center walls with R-19 ocsf; basement with R-28 ccsf, R-5 rigid foam under slab; sealed attic with R-28 ocsf under roof deck; 22.8 SEER; 12.5 HSPF heat pump.

  12. 78 FR 68777 - Proposed Establishment of Area Navigation (RNAV) Routes; Atlanta, GA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-15

    ... Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a.... 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2... Federal Aviation Administration 14 CFR Part 71 RIN 2120-AA66 Proposed Establishment of Area...

  13. Beta titanium alloys in the 80's; Proceedings of the Symposium, Atlanta, GA, March 8, 1983

    SciTech Connect

    Boyer, R.R.; Rosenberg, H.W.

    1984-01-01

    Among the topics discussed are the use of beta-Ti in the SR-71 aircraft, the microstructure and properties of beta-Ti alloys, the effects of hydrogen, heat treatment, and omega-phase formation on beta-Ti, the primary processing of beta- and near-beta-Ti alloys, the processing window for grain size control in metastable beta-Ti, grain growth in beta III-Ti, the processing and properties of Ti-17 alloy for aircraft and turbine applications, the isothermal forging of beta- and near-beta-Ti alloys, the torsional properties of beta-Ti in automotive suspension springs, and the martensitic Transage Ti alloys. Also covered are Ti-Nb superconductors, and property compilations for such commercial and developmental beta-Ti alloys as beta-III, Ti-15-3, Ti-17, Transage 134, and cast and wrought Transage 175.

  14. 77 FR 5429 - Proposed Modification of the Atlanta Class B Airspace Area; GA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-03

    ..., 1970 (35 FR 7784). The TCA was modified several times during the 1970s to accommodate revised... Reclassification Final Rule (56 FR 65638), the term ``terminal control area'' was replaced by ``Class B airspace... to the existing design. To address this situation, the FAA issued a final rule in October 2006 (71...

  15. 78 FR 70895 - Proposed Establishment and Modification of Area Navigation (RNAV) Routes; Atlanta, GA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-27

    ... Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a.... 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2...), Buffalo Niagara International (BUF) and Toronto Pearson International (TOR) airports. Additionally,...

  16. GLOBECOM '84 - Global Telecommunications Conference, Atlanta, GA, November 26-29, 1984, Conference Record. Volume 3

    NASA Astrophysics Data System (ADS)

    Attention is given to aspects of quality assurance methodologies in development life cycles, optical intercity transmission systems, multiaccess protocols, system and technology aspects in the case of regional/domestic satellites, advances in SSB-AM radio transmission over terrestrial and satellite network, and development environments for telecommunications systems. Other subjects studied are concerned with business communication networks for voice and data, VLSI in local network and communication protocol, product evaluation and support, an update regarding Videotex, topics in communication theory, topics in radio propagation, a status report regarding societal effects of technology in the workplace, digital image processing, and adaptive signal processing for communications. The management of the reliability function in the development process is considered along with Giga-bit technologies for long distance large capacity optical transmission equipment. The application of gallium arsenide analog and digital integrated circuits for high-speed fiber optical communications, and a simple algorithm for image data coding.

  17. GLOBECOM '84 - Global Telecommunications Conference, Atlanta, GA, November 26-29, 1984, Conference Record. Volume 1

    NASA Astrophysics Data System (ADS)

    The subjects discussed are related to LSI/VLSI based subscriber transmission and customer access for the Integrated Services Digital Network (ISDN), special applications of fiber optics, ISDN and competitive telecommunication services, technical preparations for the Geostationary-Satellite Orbit Conference, high-capacity statistical switching fabrics, networking and distributed systems software, adaptive arrays and cancelers, synchronization and tracking, speech processing, advances in communication terminals, full-color videotex, and a performance analysis of protocols. Advances in data communications are considered along with transmission network plans and progress, direct broadcast satellite systems, packet radio system aspects, radio-new and developing technologies and applications, the management of software quality, and Open Systems Interconnection (OSI) aspects of telematic services. Attention is given to personal computers and OSI, the role of software reliability measurement in information systems, and an active array antenna for the next-generation direct broadcast satellite.

  18. 75 FR 76953 - Reorganization of Foreign-Trade Zone 26 Under Alternative Site Framework, Atlanta, GA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-10

    ... Board adopted the alternative site framework (ASF) in December 2008 (74 FR 1170, 01/12/09; correction 74 FR 3987, 01/22/09) as an option for the establishment or reorganization of general-purpose zones... in the Federal Register (75 FR 17126-17127, 4/5/2010) and the application has been processed...

  19. Fecal-coliform bacteria concentrations in streams of the Chattahoochee River National Recreation Area, Metropolitan Atlanta, Georgia, May-October 1994 and 1995

    USGS Publications Warehouse

    Gregory, M. Brian; Frick, Elizabeth A.

    2000-01-01

    Introduction: The Metropolitan Atlanta area has been undergoing a period of rapid growth and development. The population in the 10-county metropolitan area almost doubled from about 1.5 million people in 1970 to 2.9 million people in 1995 (Atlanta Regional Commission, written commun., 2000). Residential, commercial, and other urban land uses more than tripled during the same period (Frick and others, 1998). The Chattahoochee River is the most utilized water resource in Georgia. The rapid growth of Metropolitan Atlanta and its location downstream of the headwaters of the drainage basin make the Chattahoochee River a vital resource for drinking-water supplies, recreational opportunities, and wastewater assimilation. In 1978, the U.S. Congress declared the natural, scenic, recreation, and other values of 48 miles of the Chattahoochee River from Buford Dam to Peachtree Creek to be of special national significance. To preserve this reach of the Chattahoochee River, the U.S. Congress created the Chattahoochee River National Recreational Area (CRNRA), which includes the Chattahoochee River downstream from Buford Dam to the mouth of Peachtree Creek and a series of park areas adjacent to the river in northern Metropolitan Atlanta Even with this protection, waters of the Chattahoochee River and many of its tributaries in Metropolitan Atlanta did not meet water-quality standards set for designated uses during 1994 and 1995 (fig. 1 and table 1). Much of the degradation of water quality has been associated with areas undergoing rapid urban growth and sprawling suburban development. The resulting conversion of mostly forested land to urban land has multiple adverse effects on water quality. Degradation of water quality may be caused by a number of factors including an increase in nutrient concentrations, sediment and sedimentbound contaminant concentrations (e.g., metals and pesticides) (Frick and others, 1998), and fecal-coliform bacteria concentrations (Center for Watershed

  20. Outcomes among Asylum Seekers in Atlanta, Georgia, 2003--2012.

    PubMed

    Evans, Dabney P; Donato, Caitlin E; Malewezi, Bridget A; Li, Anyie J; Corea, Mario J; Mitchell, Andrew B

    2015-10-01

    INTRODUCTION Asylum seekers face a wide array of challenges, including the need for a fair and just adjudication process. In the state of Georgia, the Atlanta Asylum Network addresses the needs of such individuals by providing them physical, psychological and gynecological assessments, the results of which are presented to the courts in the asylum appeal process. OBJECTIVE As a component of the Network's program evaluation, assess outcomes among asylum seekers using its services, as well as relation of outcomes to type of service provided, the individual's geographic origin and English language proficiency. METHODS A retrospective examination was conducted of program data gathered by the Network between 2003 and 2012. Subjects included asylum seekers who received assessments by the Network during this period. The primary variable of interest was the final case outcome, defined as determination of asylum status: granted, withholding of removal, administrative closure and prosecutorial discretion, denied or voluntary departure. Outcomes were subsequently collapsed into a single positive or negative outcome variable. Positive outcomes included asylum granted, removal withheld, administrative closure and prosecutorial discretion. Negative outcomes included asylum denied and voluntary departure. We conducted bivariate and multivariate analyses, relating final case outcomes to Network services, geographic origin and English language proficiency, among the key variables. RESULTS A total of 69 of 120 asylum seekers in the study had a known final case outcome, and of those, 63.8% (44) had a positive outcome; or 37% of the total number of asylum seekers (n = 120). Among the 20 who received 2 of the 3 types of assessment (physical, psychological, gynecological), 16 (80%) received a positive case outcome. Most persons with a known final outcome came from Africa (41), where 78% (32) of cases resulted positive. Asylum seekers not proficient in English were 2.4 times more likely

  1. Outcomes among Asylum Seekers in Atlanta, Georgia, 2003--2012.

    PubMed

    Evans, Dabney P; Donato, Caitlin E; Malewezi, Bridget A; Li, Anyie J; Corea, Mario J; Mitchell, Andrew B

    2015-10-01

    INTRODUCTION Asylum seekers face a wide array of challenges, including the need for a fair and just adjudication process. In the state of Georgia, the Atlanta Asylum Network addresses the needs of such individuals by providing them physical, psychological and gynecological assessments, the results of which are presented to the courts in the asylum appeal process. OBJECTIVE As a component of the Network's program evaluation, assess outcomes among asylum seekers using its services, as well as relation of outcomes to type of service provided, the individual's geographic origin and English language proficiency. METHODS A retrospective examination was conducted of program data gathered by the Network between 2003 and 2012. Subjects included asylum seekers who received assessments by the Network during this period. The primary variable of interest was the final case outcome, defined as determination of asylum status: granted, withholding of removal, administrative closure and prosecutorial discretion, denied or voluntary departure. Outcomes were subsequently collapsed into a single positive or negative outcome variable. Positive outcomes included asylum granted, removal withheld, administrative closure and prosecutorial discretion. Negative outcomes included asylum denied and voluntary departure. We conducted bivariate and multivariate analyses, relating final case outcomes to Network services, geographic origin and English language proficiency, among the key variables. RESULTS A total of 69 of 120 asylum seekers in the study had a known final case outcome, and of those, 63.8% (44) had a positive outcome; or 37% of the total number of asylum seekers (n = 120). Among the 20 who received 2 of the 3 types of assessment (physical, psychological, gynecological), 16 (80%) received a positive case outcome. Most persons with a known final outcome came from Africa (41), where 78% (32) of cases resulted positive. Asylum seekers not proficient in English were 2.4 times more likely

  2. Project ATLANTA (Atlanta Land use Analysis: Temperature and Air Quality): Use of Remote Sensing and Modeling to Analyze How Urban Land Use Change Affects Meteorology and Air Quality Through Time

    NASA Technical Reports Server (NTRS)

    Quattrochi, Dale A.; Luvall, Jeffrey C.; Estes, Maurice G., Jr.

    1999-01-01

    This paper presents an overview of Project ATLANTA (ATlanta Land use ANalysis: Temperature and Air-quality) which is an investigation that seeks to observe, measure, model, and analyze how the rapid growth of the Atlanta, Georgia metropolitan area since the early 1970's has impacted the region's climate and air quality. The primary objectives for this research effort are: (1) To investigate and model the relationships between land cover change in the Atlanta metropolitan, and the development of the urban heat island phenomenon through time; (2) To investigate and model the temporal relationships between Atlanta urban growth and land cover change on air quality; and (3) To model the overall effects of urban development on surface energy budget characteristics across the Atlanta urban landscape through time. Our key goal is to derive a better scientific understanding of how land cover changes associated with urbanization in the Atlanta area, principally in transforming forest lands to urban land covers through time, has, and will, effect local and regional climate, surface energy flux, and air quality characteristics. Allied with this goal is the prospect that the results from this research can be applied by urban planners, environmental managers and other decision-makers, for determining how urbanization has impacted the climate and overall environment of the Atlanta area. Multiscaled remote sensing data, particularly high resolution thermal infrared data, are integral to this study for the analysis of thermal energy fluxes across the Atlanta urban landscape.

  3. Evaluation of streamwater quality in the Atlanta region

    USGS Publications Warehouse

    Peters, Norman E.; Kandell, Stephen J.; Hatcher, Kathryn J.

    1997-01-01

    A water-quality index (WQI) was developed from historical data for streams in the Atlanta region. The WQI was derived from percentile ranks of individual water-quality parameter values at each stream by normalizing the constituent ranks for values from all sites in the area for the period from 1990 to 1995. WQIs were developed primarily for nutrients and nutrient-related parameters, because data for metals, organics (pesticides and herbicides), biological conditions, and suspended sediment generally were unavailable. Average WQI of the individual parameter WQIs for sites in the region ranged from 0.26 (good quality) to 0.86 (poor quality), and increased downstream of known nutrient sources. Annual average site WQI decreased at most long-term monitoring sites from 1986 to 1995. Temporal trends, in part, reflect effects of a drought in the late 1980's and normal to higher-than-normal rainfall and runoff in the 1990's. For several sites, particularly in the northern part of the region where major development is ongoing, WQI increased dramatically from 1994 to 1995. Interannual WQI variability typically was less than spatial variability. Average annual site WQI for individual parameters correlated with annual hydrologic characteristics, particularly precipitation amount and water yield, reflecting the effect of dilution on individual water-quality parameter values.

  4. Solar hot water system installed at Day's Lodge, Atlanta, Georgia

    SciTech Connect

    1980-09-01

    The solar energy hot water system installed in the Days Inns of America, Inc., Day's Lodge I-85 and Shallowford Road, NE Atlanta, Georgia is described. This system is one of eleven systems planned under this grant and was designed to provide for 81% of the total hot water demand. There are two separate systems, each serving one building of the lodge (total of 65 suites). The entire system contains only potable city water. The 1024 square feet of Grumman Sunstream Model 332 liquid flat plate collectors and the outside piping drains whenever the collector plates approach freezing or when power is interrupted. Solar heated water from the two above ground cement lined steel tanks (1000 gallon tank) is drawn into the electric domestic hot water (DHW) tanks as hot water is drawn. Electric resistance units in the DHW tanks top off the solar heated water, if needed, to reach thermostat setting. Operation of this system was begun in August, 1979. The solar components were partly funded ($18,042 of $36,084 cost) by the Department of Energy.

  5. Metro Atlanta responds to West Nile virus: a coordinated public health response.

    PubMed

    Willis, Juanette

    2005-01-01

    Three and a half million people live in metropolitan Atlanta, in multiple counties with varying population bases, resources, issues and separate boards of health. Historically, public health issues have been managed within each county, with very little sharing of information among counties. The 1999 West Nile virus (WNV) outbreak in the Northeast caused public health officials in Atlanta to recognize the potential for the disease to spread to Georgia and the need to develop a coordinated, multi-jurisdictional response plan. This plan would need to address a new disease with little scientific data to predict how it might behave in a new environment and would also require closely coordinated communication among the local/state public health entities and elected officials. In early 2000, staff from the five health districts in the metro Atlanta area and the state health department voluntarily convened the Metro Atlanta Surveillance Task Force (MASTF) to create the Metro Atlanta West Nile Virus Response Plan. This plan utilizes a coordinated effort encompassing public education, surveillance, and mosquito control. With this plan in place, when the first human case of WNV was detected in Atlanta, the public heard consistent health messages about preventive measures to lower their risk of illness and the metro counties were able to carry out a successful uniform approach to mosquito control. This plan has received recognition by the National Association of County and City Health Officials (NACCHO) as a 2004 Model Practice, demonstrating exemplary and replicable qualities in response to a local public health need. Since the early days of the emergence of WNV in the metro Atlanta area, MASTF has continued to be a viable, evolving entity, managing and anticipating health issues. The MASTF plan is a successful effort to develop consistent policies and procedures for disease surveillance in a heavily populated area with multiple local health departments. PMID:15822839

  6. 1986 AAPT/APS Joint Winter Meeting Abstracts and Detailed Schedule.

    ERIC Educational Resources Information Center

    AAPT Announcer, 1985

    1985-01-01

    The joint winter meeting of the American Association of Physics Teachers (AAPT) and the American Physical Society (APS) was held in Atlanta, Georgia, January 27-30, 1986. Abstracts of papers presented at the meeting and the complete program are provided. An author index is appended. (JN)

  7. The U.S. Geological Survey and City of Atlanta water-quality and water-quantity monitoring network

    USGS Publications Warehouse

    Horowitz, Arthur J.; Hughes, W. Brian

    2006-01-01

    Population growth and urbanization affect the landscape, and the quality and quantity of water in nearby rivers and streams, as well as downstream receiving waters (Ellis, 1999). Typical impacts include: (1) disruption of the hydrologic cycle through increases in the extent of impervious surfaces (e.g., roads, roofs, sidewalks) that increase the velocity and volume of surface-water runoff; (2) increased chemical loads to local and downstream receiving waters from industrial sources, nonpoint-source runoff, leaking sewer systems, and sewer overflows; (3) direct or indirect soil contamination from industrial sources, power-generating facilities, and landfills; and (4) reduction in the quantity and quality of aquatic habitats. The City of Atlanta's monitoring network consists of 21 long-term sites. Eleven of these are 'fully instrumented' to provide real-time data on water temperature, pH, specific conductance, dissolved oxygen, turbidity (intended as a surrogate for suspended sediment concentration), water level (gage height, intended as a surrogate for discharge), and precipitation. Data are transmitted hourly and are available on a public Web site (http://ga.water.usgs.gov/). Two sites only measure water level and rainfall as an aid to stormwater monitoring. The eight remaining sites are used to assess water quality.

  8. Green roof adoption in atlanta, georgia: the effects of building characteristics and subsidies on net private, public, and social benefits.

    PubMed

    Mullen, Jeffrey D; Lamsal, Madhur; Colson, Greg

    2013-10-01

    This research draws on and expands previous studies that have quantified the costs and benefits associated with conventional roofs versus green roofs. Using parameters from those studies to define alternative scenarios, we estimate from a private, public, and social perspective the costs and benefits of installing and maintaining an extensive green roof in Atlanta, GA. Results indicate net private benefits are a decreasing function of roof size and vary considerably across scenarios. In contrast, net public benefits are highly stable across scenarios, ranging from $32.49 to $32.90 m(-2). In addition, we evaluate two alternative subsidy regimes: (i) a general subsidy provided to every building that adopts a green roof and (ii) a targeted subsidy provided only to buildings for which net private benefits are negative but net public benefits are positive. In 6 of the 12 general subsidy scenarios the optimal public policy is not to offer a subsidy; in 5 scenarios the optimal subsidy rate is between $20 and $27 m(-2); and in 1 scenario the optimal rate is $5 m(-2). The optimal rate with a targeted subsidy is between $20 and $27 m(-2) in 11 scenarios and no subsidy is optimal in the twelfth. In most scenarios, a significant portion of net public benefits are generated by buildings for which net private benefits are positive. This suggests a policy focused on information dissemination and technical assistance may be more cost-effective than direct subsidy payments.

  9. New Horizons at Pluto: An Overview of Educational Activities / Outreach at Fernbank Science Center, Atlanta, Georgia (USA)

    NASA Astrophysics Data System (ADS)

    Albin, Edward F.; Harris, R. Scott

    2015-11-01

    We report on educational activities and associated outreach at Fernbank Science Center (Atlanta, GA) in conjunction with the July 2015 New Horizons spacecraft encounter at Pluto. On encounter day, a public lecture about the dwarf planet was presented by Georgia’s NASA Solar System ambassador to kick off the arrival of the space probe at Pluto. In the months following the flyby, we presented a program called “Exploring New Horizons” in the Science Center’s Zeiss planetarium. This program is a digital full-dome presentation about the discovery of Pluto and its subsequent exploration - including an overview of the New Horizons mission. Since NASA continues to receive data from the probe, a brief update (tribute) is included at the end of each planetarium program that features the latest imagery and data from the dwarf planet. We anticipate running the planetarium program throughout the fall semester of 2015. With Pluto visible in the early evening autumn sky, observations are possible with Center’s 0.9 m telescope, which is open for public viewing on clear Thursday and Friday nights following the planetarium program. Although Pluto is somewhat faint through the telescope's eyepiece, it is visible and clearly identified within the surrounding starfield. Intermittent post-encounter lectures ("Messages from the Outer Solar System") have been given on Friday evenings as well. Finally, due to the continued interest in Pluto, we have developed a new outreach program about dwarf planets in general, geared towards 4th - 6th students.

  10. Urbanization effects on the hydrology of the Atlanta, Georgia (USA)

    USGS Publications Warehouse

    Peters, N.E.; Rose, S.

    2001-01-01

    For the period from 1958 to 1996, streamflow and rainfall characteristics of a highly urbanized watershed were compared with less-urbanized and non-urbanized watersheds in the vicinity of Atlanta, Georgia (USA). Water levels in several wells completed in surficial and crystalline-rock aquifers also were evaluated. Annual runoff coefficients (runoff as a fractional percentage of precipitation) ranged from 0.31 to 0.34 and were not significantly different for the urban stream (Peachtree Creek). Peak flows for the largest 25 stormflows at Peachtree Creek were 30% to 80% greater than peak flows for the other streams. A 2-day storm recession constant for Peachtree Creek was much larger, that is streamflow decreased more rapidly than for the other streams. Average low flow of Peachtree Creek was 25 to 35% less than the other streams, possibly the result of decreased infiltration caused by the more efficient routing of storm water and the paving of groundwater recharge areas. The timing of groundwater level variations was similar annually in each well, reflecting the seasonal recharge. Although water level monitoring only began during the late 1970s and early 1980s for the two urban wells, water levels in these wells have been declining compared to non-urban wells since then. The water level decline is attributed to decreased groundwater recharge in the urban watersheds due to increased imperviousness and related rapid storm runoff. Likewise, the increased urbanization from the 1960s to the 1990s of the Peachtree Creek watershed produced more runoff than urbanization in the less urbanized Big Creek and Sweetwater Creek watersheds.

  11. SHORT-TERM TEMPORAL VARIATION IN PM2.5 MASS AND CHEMICAL COMPOSITION DURING THE ATLANTA SUPERSITE EXPERIMENT, 1999

    EPA Science Inventory

    Measurements in urban Atlanta of transient aerosol events in which PM2.5 mass concentrations rapidly rise and fall over a period of 3-6 hr are reported. The data are based on new measurement techniques demonstrated at the U.S. Environmental Protection Agency (EPA) Atlanta Supe...

  12. INTERCOMPARISION OF SEMI-CONTINUOUS MEASUREMENTS OF NITRATE AND SULFATE AT THE EPA ATLANTA SUPERSITE, AUGUST 1999

    EPA Science Inventory

    The Atlanta Supersite was one of the first Environmental Protection Agency (EPA) Supersites dedicated to the study of fine particles (PM2.5). The study involved intensive measurements during the month of August 1999, at a site situated near the center of Atlanta. One of the s...

  13. A Dynamic Optimization Technique for Siting the NASA-Clark Atlanta Urban Rain Gauge Network (NCURN)

    NASA Technical Reports Server (NTRS)

    Shepherd, J. Marshall; Taylor, Layi

    2003-01-01

    NASA satellites and ground instruments have indicated that cities like Atlanta, Georgia may create or alter rainfall. Scientists speculate that the urban heat island caused by man-made surfaces in cities impact the heat and wind patterns that form clouds and rainfall. However, more conclusive evidence is required to substantiate findings from satellites. NASA, along with scientists at Clark Atlanta University, are implementing a dense, urban rain gauge network in the metropolitan Atlanta area to support a satellite validation program called Studies of PRecipitation Anomalies from Widespread Urban Landuse (SPRAWL). SPRAWL will be conducted during the summer of 2003 to further identify and understand the impact of urban Atlanta on precipitation variability. The paper provides an. overview of SPRAWL, which represents one of the more comprehensive efforts in recent years to focus exclusively on urban-impacted rainfall. The paper also introduces a novel technique for deploying rain gauges for SPRAWL. The deployment of the dense Atlanta network is unique because it utilizes Geographic Information Systems (GIS) and Decision Support Systems (DSS) to optimize deployment of the rain gauges. These computer aided systems consider access to roads, drainage systems, tree cover, and other factors in guiding the deployment of the gauge network. GIS and DSS also provide decision-makers with additional resources and flexibility to make informed decisions while considering numerous factors. Also, the new Atlanta network and SPRAWL provide a unique opportunity to merge the high-resolution, urban rain gauge network with satellite-derived rainfall products to understand how cities are changing rainfall patterns, and possibly climate.

  14. Proceedings of the Annual National Agricultural Education Research Meeting (12th, Atlanta, Georgia, December 6, 1985).

    ERIC Educational Resources Information Center

    American Vocational Association, Arlington, VA. Agricultural Education Div.

    These proceedings include the following papers: "An Assessment of the National FFA Public Service Announcement Program" (Sutphin, Dillon, and Rush); "Educational Objectives and Administrative Criteria for the National FFA Contest Program" (Smith and Kahler); "A National Profile of Agricultural Teacher Educators and State Supervisors of Vocational…

  15. Status and trends in atmospheric deposition and emissions near Atlanta, Georgia, 1986-99

    USGS Publications Warehouse

    Peters, N.E.; Meyers, T.P.; Aulenbach, Brent T.

    2002-01-01

    Wet and dry atmospheric deposition were investigated from weekly data, 1986-99 (1986-97 for dry deposition) at the Panola Mountain Research Watershed (PMRW), a forested research site 25 km, southeast of Atlanta, Georgia. Furthermore, the wet deposition was compared to that at three adjacent National Atmospheric Deposition Program's National Trends Network (NTN) sites (GA41, 50 km south of PMRW; AL99, 175 km northwest; NC25, 175 km north-northeast) and dry deposition was compared to that at adjacent Clean Air Status and Trends Network (CASTNET) sites, co-located at the NTN sites. The pH of precipitation is acidic and the dominant acid anion is SO4; the pH (derived from the volume-weighted mean H concentration) averages 4.44 for 1986-99, and varies seasonally with average lowest values in summer (4.19) and highest in winter (4.63). From 1986-99, the annual wet deposition of sulfur (S) and nitrogen (N) averaged 400 and 300 eq ha-1 (6.4 and 4.2 kg ha-1), respectively. Inferential model estimates of annual dry S and N deposition from 1986-97 averaged 130 and 150 eq ha-1 (2.1 and 2.1 kg ha-1), respectively. From 1993-99, net S deposition (dry deposition plus canopy interactions) for coniferous and deciduous throughfall (throughfall minus wet-only deposition) averaged 400 and 150 eq ha-1 (6.4 and 2.1 kg ha-1), respectively. The annual wet deposition of S and N species at PMRW was comparable to that at NTN sites, with the exception of higher N species deposition at AL99 and relatively lower H, SO4 and NO3 deposition at GA41. Dry S deposition at PMRW differed markedly from the CASTNET sites despite similarity in S concentrations for all but NC25; the differences are attributed to differences in model parameters associated with the landscape and vegetation characteristics at the sites. At PMRW, atmospheric deposition trends were not detected for the entire sampling period, but were detected for shorter periods (4-5yr). Annual S and N deposition increased from 1986 to 1991

  16. A COMPARISON OF PARTICLE MASS SPECTROMETERS DURING THE 1999 ATLANTA SUPERSITES EXPERIMENT

    EPA Science Inventory

    During the Atlanta SuperSite Experiment, four particle mass spectrometers were operated together for the first time: NOAA's PALMS (Particle Analysis by Laser Mass Spectrometry), U. C. Riverside's ATOFMS (Aerosol Time-of-Flight Mass Spectrometry), U. Delaware's RSMS-II (Rapid Si...

  17. Solar Heating and Cooling Experiment for a School in Atlanta. Performance Report.

    ERIC Educational Resources Information Center

    Westinghouse Electric Corp., Falls Church, VA.

    This report documents the performance and conclusions of a 13-month period of monitoring the performance of the experimental solar heating and cooling system installed in the George A. Towns Elementary School, Atlanta, Georgia. The objectives of the project were to (1) make a significant contribution to solar design, technology, and acceptability;…

  18. Counseling Psychology from Greyston to Atlanta: On the Road to Armageddon?

    ERIC Educational Resources Information Center

    Sprinthall, Norman A.

    1990-01-01

    Briefly describes the model for counseling psychology developed during the Greyston Conference of 1964 and compares it with the current view from the Atlanta Conference. Suggests that the shift of counseling psychology from schools, colleges, and career development toward a medical model of clinical treatment may eliminate an independent…

  19. 75 FR 17126 - Foreign-Trade Zone 26-Atlanta, Georgia, Application for Expansion and Reorganization under...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-05

    ... the Hartsfield-Jackson Atlanta International Airport in Clayton and Fulton Counties including jet fuel... Reorganization under Alternative Site Framework An application has been submitted to the Foreign-Trade Zones (FTZ... authority to expand the zone and reorganize under the alternative site framework (ASF) adopted by the...

  20. 78 FR 20091 - Foreign-Trade Zone 26-Atlanta, Georgia, Authorization of Production Activity, Perkins Shibaura...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-03

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE Foreign-Trade Zones Board Foreign-Trade Zone 26--Atlanta, Georgia, Authorization of Production Activity, Perkins Shibaura Engines, LLC (Diesel Engines), Griffin, Georgia On November 29, 2012, Georgia Foreign-Trade Zone, Inc., grantee of FTZ 26,...

  1. Three Georgias in Atlanta: Lessons from Business Schools about Finding Your Identity

    ERIC Educational Resources Information Center

    Wolverton, Mimi

    2006-01-01

    Purpose: The purpose of this paper is to look into how universities identify themselves and the audiences they choose to serve, taking into account three specific universities in Atlanta, Georgia. Design/methodology/approach: The paper gives brief overviews of the literature on differentiation and sustainability and the study, followed by…

  2. Climbing the Ladder of Reading Proficiency: The First Two Years of Atlanta's Dunbar Learning Complex

    ERIC Educational Resources Information Center

    Annie E. Casey Foundation, 2012

    2012-01-01

    Every weekday morning, Director Steve White and 40 teachers welcome 206 children to the Early Learning and Literacy Resource Center (ELLRC) in Atlanta. Upstairs in the same building, Principal Karen Brown-Collier and 30 full-time teachers welcome 385 students to Dunbar Elementary School. These children and their parents are benefiting from an…

  3. Fight or Flight? Immigration, Competition, and Language Assistance Resources in Metropolitan Atlanta

    ERIC Educational Resources Information Center

    Tarasawa, Beth

    2013-01-01

    As the Latino/a immigrant population increases, racial conflict historically understood in terms of Black and White in the U.S. South has expanded to include new contestants in metro-Atlanta public schools. By examining market and sociological competition theoretical perspectives, this study investigates how language assistance resource…

  4. The Atlanta University Center: A Consortium-Based Dual Degree Engineering Program

    ERIC Educational Resources Information Center

    Jackson, Marilyn T.

    2007-01-01

    The Atlanta University Center (AUC) comprises five historically black colleges and a centralized library. All are separate institutions, each having its own board of directors, president, infrastructure, students, faculty, staff, and traditions. To encourage coordination of effort and resources, the AUC was formed and the first formal cooperative…

  5. Social Support and Social Network Ties among the Homeless in a Downtown Atlanta Park

    ERIC Educational Resources Information Center

    Reitzes, Donald C.; Crimmins, Timothy J.; Yarbrough, Johanna; Parker, Josie

    2011-01-01

    This study applies a typology of social support with 3 categories of social networks to investigate social ties and their benefits for homeless people. Data were derived from a 2-year long series of participant observations of homeless or precariously housed people who came regularly to a downtown Atlanta public park. The findings are as follows:…

  6. Mixed Messages in Media Coverage of Bilingual Education: The Case of Atlanta, Georgia

    ERIC Educational Resources Information Center

    Tarasawa, Beth

    2008-01-01

    As the increasing number of Latino and Asian immigrants to the Atlanta area has escalated tensions over occupational, residential, and educational resources, research has begun to examine opposition to bilingual education as an extension of anti-immigrant prejudice and as a measure of perceived threat. This study uses content analysis to compare…

  7. 78 FR 65877 - Approval and Promulgation of Implementation Plans; Atlanta, Georgia 1997 8-Hour Ozone...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-04

    ... noted, EPA has already approved Rule (jjj). See 64 FR 67491 and 74 FR 62249. This rulemaking does not... Georgia's ROP plan for the 1-hour ozone NAAQS for the Atlanta Area on April 26, 1999. See 64 FR 20196. \\3..., Paulding, and Rockdale. See 56 FR 56694, November 6, 1991. \\4\\ Seven additional ``ring'' counties...

  8. Changing Land Use: Peachtree Street, Atlanta. A Case Study in Sequent Occupance [And] Student Work Book.

    ERIC Educational Resources Information Center

    Laws, Kevin

    A social studies unit and student workbook explore the historical geography of the area of Peachtree Street in Atlanta, Georgia. The unit deals with sequent occupance, a type of historical geography in which students study the same area, the changes in culture, and the changing land use in the area during certain time periods. For each period,…

  9. Evaluation of an Intervention to Reduce Playground Hazards in Atlanta Child-Care Centers.

    ERIC Educational Resources Information Center

    Sacks, Jeffrey J.; And Others

    1992-01-01

    Revisits 58 child care centers in Atlanta (Georgia) that had received interventions alerting directors to playground safety hazards. Comparison with 71 control centers randomly selected found averages of 9.4 hazards at intervention center playgrounds and 8.0 hazards at control centers. These results indicate the ineffectiveness of the…

  10. 75 FR 15415 - Expansion of Foreign-Trade Zone 26, Atlanta, Georgia, Area

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-29

    ... given in the Federal Register (73 FR 60676-60677, 10/14/08; correction, 73 FR 63675, 10/27/ 08) and the... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE Foreign-Trade Zones Board Expansion of Foreign-Trade Zone 26, Atlanta, Georgia, Area Pursuant to...

  11. Newcastle disease B1 vaccine strain in wild rock pigeons in Atlanta, Georgia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    From June to October of 2012, samples were collected from wild Rock Pigeons (Columba livia) in urban neighborhoods of Atlanta, Georgia to ascertain the prevalence of pigeon paramyxovirus serotype-1 (PPMV-1). PPMV-1 strains are a subset of avian paramyxovirus serotype-1 (APMV-1) commonly isolated fro...

  12. PREFACE TO SPECIAL SECTION: SOUTHERN OXIDANTS STUDY 1999 ATLANTA SUPERSITE PROJECT (SOS3)

    EPA Science Inventory

    The Atlanta Supersites Project consisted of a one-month intensive field program to compare advanced methods for measurement of PM2.5 mass, chemical composition, including single particle composition in real-time, and aerosol precursor species. The project was the first of EPA's ...

  13. Energy in Agriculture: Proceedings of a Conference-Workshop, Atlanta, Georgia, October 1-3, 1975.

    ERIC Educational Resources Information Center

    Southern Regional Education Board, Atlanta, GA.

    This publication is the proceedings of a conference-workshop held in Atlanta, Georgia in October 1975. At this conference 13 papers were presented on various aspects of energy use in agriculture. Also included are the final reports of the extension, the teaching, and the research workshop groups. Title of papers include Energy in Agriculture and…

  14. Anything's Possible: Project RESCUE Helping Dreams Become Reality in Inner-City Atlanta.

    ERIC Educational Resources Information Center

    Walker, Pam

    This case study describes Project RESCUE (Refer, Evaluate, Support, Coordinate, Uncover, and Educate), an agency providing support to children and adults with developmental disabilities in Fulton and DeKalb counties in and around Atlanta, Georgia. Project RESCUE's mission is to assist people in four areas: (1) to identify and obtain community…

  15. Underlying Factors Related to the Atlanta Cheating Scandal: An Autoethnographic Account

    ERIC Educational Resources Information Center

    Beal, Emma Mumphery

    2012-01-01

    In this study I used autoethnography to analyze fifty years of African-American educational history in Georgia. The impetus for the study was the Atlanta cheating scandal, widely interpreted as a character problem for individual teachers and administrators. As a lifelong resident of Georgia, a student, a public school teacher, and a parent, it…

  16. Meteorological detrending of primary and secondary pollutant concentrations: Method application and evaluation using long-term (2000-2012) data in Atlanta

    NASA Astrophysics Data System (ADS)

    Henneman, Lucas R. F.; Holmes, Heather A.; Mulholland, James A.; Russell, Armistead G.

    2015-10-01

    The effectiveness of air pollution regulations and controls are evaluated based on measured air pollutant concentrations. Air pollution levels, however, are highly sensitive to both emissions and meteorological fluctuations. Therefore, an assessment of the change in air pollutant levels due to emissions controls must account for these meteorological fluctuations. Two empirical methods to quantify the impact of meteorology on pollutant levels are discussed and applied to the 13-year time period between 2000 and 2012 in Atlanta, GA. The methods employ Kolmogorov-Zurbenko filters and linear regressions to detrended pollutant signals into long-term, seasonal, weekly, short-term, and white-noise components. The methods differ in how changes in weekly and holiday emissions are accounted for. Both can provide meteorological adjustments on a daily basis for future use in acute health analyses. The meteorological impact on daily signals of ozone, NOx, CO, SO2, PM2.5, and PM species are quantified. Analyses show that the substantial decreases in seasonal averages of NOx and SO2 correspond with controls implemented in the metropolitan Atlanta area. Detrending allows for the impacts of some controls to be observed with averaging times of as little as 3 months. Annual average concentrations of NOx, SO2, and CO have all fallen by at least 50% since 2000. Reductions in NOx levels, however, do not lead to uniform reductions in ozone. While average detrended summer average maximum daily average 8 h ozone (MDA8h O3) levels fell by 4% (2.2 ± 2 ppb) between 2000 and 2012, winter averages have increased by 12% (3.8 ± 1.4 ppb), providing further evidence that high ozone levels are NOx-limited and lower ozone concentrations are NOx-inhibited. High ozone days (with MDA8h O3 greater than 60 ppb) decreased both in number and in magnitude over the study period.

  17. Intercomparison of an Aerosol Chemical Speciation Monitor (ACSM) with ambient fine aerosol measurements in downtown Atlanta, Georgia

    NASA Astrophysics Data System (ADS)

    Budisulistiorini, S. H.; Canagaratna, M. R.; Croteau, P. L.; Baumann, K.; Edgerton, E. S.; Kollman, M. S.; Ng, N. L.; Verma, V.; Shaw, S. L.; Knipping, E. M.; Worsnop, D. R.; Jayne, J. T.; Weber, R. J.; Surratt, J. D.

    2014-07-01

    Currently, there are a limited number of field studies that evaluate the long-term performance of the Aerodyne Aerosol Chemical Speciation Monitor (ACSM) against established monitoring networks. In this study, we present seasonal intercomparisons of the ACSM with collocated fine aerosol (PM2.5) measurements at the Southeastern Aerosol Research and Characterization (SEARCH) Jefferson Street (JST) site near downtown Atlanta, GA, during 2011-2012. Intercomparison of two collocated ACSMs resulted in strong correlations (r2 > 0.8) for all chemical species, except chloride (r2 = 0.21) indicating that ACSM instruments are capable of stable and reproducible operation. In general, speciated ACSM mass concentrations correlate well (r2 > 0.7) with the filter-adjusted continuous measurements from JST, although the correlation for nitrate is weaker (r2 = 0.55) in summer. Correlations of the ACSM NR-PM1 (non-refractory particulate matter with aerodynamic diameter less than or equal to 1 μm) plus elemental carbon (EC) with tapered element oscillating microbalance (TEOM) PM2.5 and Federal Reference Method (FRM) PM1 mass are strong with r2 > 0.7 and r2 > 0.8, respectively. Discrepancies might be attributed to evaporative losses of semi-volatile species from the filter measurements used to adjust the collocated continuous measurements. This suggests that adjusting the ambient aerosol continuous measurements with results from filter analysis introduced additional bias to the measurements. We also recommend to calibrate the ambient aerosol monitoring instruments using aerosol standards rather than gas-phase standards. The fitting approach for ACSM relative ionization for sulfate was shown to improve the comparisons between ACSM and collocated measurements in the absence of calibrated values, suggesting the importance of adding sulfate calibration into the ACSM calibration routine.

  18. Classification of the PALMS single particle mass spectral data from Atlanta by regression tree analysis

    NASA Astrophysics Data System (ADS)

    Middlebrook, A. M.; Murphy, D. M.; Lee, S.; Lee, S.; Lee, S.; Thomson, D. S.; Thomson, D. S.

    2001-12-01

    During the Atlanta Supersites project in August 1999, the PALMS (Particle Analysis by Laser Mass Spectrometry) instrument collected over 500,000 individual particle spectra. The Atlanta data were originally analyzed by examining combinations of peaks and relative peak areas [Lee et al., 2001a,b], and a wide range of particle components such as sulfate, nitrate, mineral species, metals, organic species, and elemental carbon were detected. To further study the dataset, a classification program using regression tree analysis was developed and applied. Spectral data were compressed into a lower resolution spectrum (every 0.25 mass units) of the raw data and a list of peak areas (every mass unit). Each spectrum started as a normalized classification vector by itself. If the dot product of two classification vectors was within a certain threshold, they were combined into a new classification. The new classification vector was a normalized running average of the classifications being combined. In subsequent steps, the threshold for combining classifications was continuously lowered until a reasonable number of classifications remained. After the final iteration, each spectrum was compared individually with the entire set of classification vectors. Classifications were also combined manually. The classification results from the Atlanta data are generally consistent with those determined by peak identification. However, the classification program identified specific patterns in the mass spectra that were not found by peak identification and generated new particle types. Furthermore, rare particle types that may affect human health were studied in more detail. A description of the classification program as well as the results for the Atlanta data will be presented. Lee, S.-H., D. M. Murphy, D. S. Thomson, and A. M. Middlebrook, Chemical components of single particles measured with particle analysis by laser mass spectrometry (PALMS) during the Atlanta Supersites Project

  19. ATLANTA COMMUTE VEHICLE SOAK AND START DISTRIBUTIONS AND ENGINE STARTS PER DAY: IMPACT ON MOBILE SOURCE EMISSION RATES

    EPA Science Inventory

    Georgia Institute of Technology School of Civil and Environmental Engineering researchers analyzed the 2004 vehicle activity data obtained from vehicles in the Atlanta Commuter Choice Value Pricing Initiative. The onboard monitoring equipment installed in each participating vehi...

  20. Minutes of the Tank Waste Science Panel meeting July 9--1, 1991

    SciTech Connect

    Strachan, D.M.

    1992-04-01

    The fifth meeting of the Tank Waste Science Panel was held July 9--11, 1991, in Atlanta, Georgia. The subject areas included the generation, retention, and release of gases from Tank 241-SY-101 and the chemistry of ferrocyanide wastes.

  1. Urban Heat Islands and Summertime Convective Thunderstorms in Atlanta: Three Case Studies

    NASA Technical Reports Server (NTRS)

    Bornstein, Robert; Lin, Qinglu; Goodman, H. Michael (Technical Monitor)

    1999-01-01

    Data from both 27 sites in the Atlanta mesonet surface meteorological network and eight National Weather Service sites were analyzed for the period from 26 July to 3 August 1996. Analysis of the six precipitation events over the city during the period (each on a different day) showed that its urban heat island (UHI) induced a convergence zone that initiated three of the storms at different times of the day, i.e., 0630,0845, and 1445 EDT. Previous analysis has shown that New York City (NYC) effects summer daytime thunderstorm formation and/or movement. That study found that during nearly calm regional flow conditions the NYC UHI initiates convective activity. Moving thunderstorms, however, tended to bifurcate and to move around the city, due to its building barrier effect. The current Atlanta results thus agree with the NYC results with respect to thunderstorm initiation.

  2. Ground-water resources of the south metropolitan Atlanta region, Georgia

    USGS Publications Warehouse

    Clarke, John S.; Peck, Michael F.

    1991-01-01

    Ground-water resources of the nine county south metropolitan Atlanta region were evaluated in response to an increased demand for water supplies and concern that existing surface water supplies may not be able to meet future supply demands. Previous investigations have suggested that crystalline rock in the study area has low permeability and can not sustain well yields suitable for public supply. However, the reported yield for 406 wells drilled into crystalIine rock units in this area ranged from less than 1 to about 700 gallons per minute, and averaged 43 gallons per minute. The reported flow from 13 springs ranged from 0.5 to 679 gallons per minute. The yield of 43 wells and flow from five springs was reported to exceed 100 gallons per minute. Most of the high-yielding wells and springs were near contact zones between rocks of contrasting lithologic and weathering properties. The high-yielding wells and springs are located in a variety of topographic settings: hillsides, upland draws, and hilltops were most prevalent. The study area, which includes Henry, Fayette, Coweta, Spalding, Lamar, Pike, Meriwether, Upson and Talbot Counties, is within the Piedmont physiographic province except for the southernmost part of Talbot County, which is in the Coastal Plain physiographic province. In the Piedmont, ground-water storage occurs in joints, fractures and other secondary openings in the bedrock, and in pore spaces in the regolith. The most favorable geologic settings for siting highyielding wells are along contact zones between rocks of contrasting lithology and permeability, major zones of fracturing such as the Towaliga and Auchumpkee fault zones, and other numerous shear and microbreccia zones. Although most wells in the study area are from 101 to 300 feet deep, the highest average yields were obtained from wells 51 to 100 feet deep, and 301 to 500 feet deep. Of the wells inventoried, the average diameter of well casing was largest for wells located on hills and

  3. Medical Education in Atlanta and Health Care of Black Minority and Low-Income People

    PubMed Central

    Yancey, Asa G.

    1988-01-01

    In this W. Montague Cobb lecture, the author addresses the status of hospitals for the black minority and the poor in Atlanta, the founding of Morehouse School of Medicine, health care for the disadvantaged, the need for minority health care professionals, and the lack of health insurance among the poor. A greater educational effort is needed to bring about change in the high incidence of homicide, the unhealthy lifestyles, and the disproportionate number of AIDS cases in the black population. PMID:3290504

  4. Medical and public health services at the 1996 Atlanta Olympic Games: an overview.

    PubMed

    Brennan, R J; Keim, M E; Sharp, T W; Wetterhall, S F; Williams, R J; Baker, E L; Cantwell, J D; Lillibridge, S R

    Planning for the 2000 Sydney Olympic Games may benefit from the experience of the 1996 Atlanta Olympics. Excellent health promotion and prevention activities before and during the Games resulted in fewer medical and public health problems than anticipated. Despite this, there was room for improvement in the level of communication and cooperation between the many service providers to ensure the most appropriate and efficient responses. PMID:9418799

  5. A Remote Sensing Approach for Urban Environmental Decision-Making: An Atlanta, Georgia Case Study

    NASA Technical Reports Server (NTRS)

    Quattrochi, Dale A.; Luvall, Jeffrey C.; Rickman, Douglas L.; Laymon, Charles A.; Estes, Maurice G., Jr.; Howell, Burgess F.; Arnold, James E. (Technical Monitor)

    2002-01-01

    Unquestionably, urbanization causes tremendous changes in land cover and land use, as well as impacting a host of environmental characteristics. For example, unlike natural surfaces, urban surfaces have very different thermal energy properties whereby they store solar energy throughout the day and continue to release it as heat well after sunset. This effect, known as the 'Urban Heat Island', serves as a catalyst for chemical reactions from vehicular exhaust and industrial activities leading to the deterioration in air quality, especially exacerbating the production of ground level ozone. 'Cool Community' strategies that utilize remote sensing data, are now being implemented as a way to reduce the impacts of the urban heat island and its subsequent environmental impacts. This presentation focuses on how remote sensing data have been used to provide descriptive and quantitative data for characterizing the Atlanta, Georgia metropolitan area - particularly for measuring surface energy fluxes, such as the thermal or "heat" energy that emanates from different land cover types across the Atlanta urban landscape. In turn, this information is useful for developing a better understanding of how the thermal characteristics of the city surface affect the urban heat island phenomena and, ultimately, air quality and other environmental parameters over the Atlanta metropolitan region. Additionally, this paper also provides insight on how remote sensing, with its synoptic approach, can be used to provide urban planners, local, state, and federal government officials, and other decision-makers, as well as the general public, with information to better manage urban areas as sustainable environments.

  6. UNDERSTANDING THE INTERNATIONAL CONSENSUS FOR ACUTE PANCREATITIS: CLASSIFICATION OF ATLANTA 2012

    PubMed Central

    de SOUZA, Gleim Dias; SOUZA, Luciana Rodrigues Queiroz; CUENCA, Ronaldo Máfia; JERÔNIMO, Bárbara Stephane de Medeiros; de SOUZA, Guilherme Medeiros; VILELA, Vinícius Martins

    2016-01-01

    ABSTRACT Introduction: Contrast computed tomography and magnetic resonance imaging are widely used due to its image quality and ability to study pancreatic and peripancreatic morphology. The understanding of the various subtypes of the disease and identification of possible complications requires a familiarity with the terminology, which allows effective communication between the different members of the multidisciplinary team. Aim: Demonstrate the terminology and parameters to identify the different classifications and findings of the disease based on the international consensus for acute pancreatitis ( Atlanta Classification 2012). Methods: Search and analysis of articles in the "CAPES Portal de Periódicos with headings "acute pancreatitis" and "Atlanta Review". Results: Were selected 23 articles containing radiological descriptions, management or statistical data related to pathology. Additional statistical data were obtained from Datasus and Population Census 2010. The radiological diagnostic criterion adopted was the Radiology American College system. The "acute pancreatitis - 2012 Rating: Review Atlanta classification and definitions for international consensus" tries to eliminate inconsistency and divergence from the determination of uniformity to the radiological findings, especially the terminology related to fluid collections. More broadly as "pancreatic abscess" and "phlegmon" went into disuse and the evolution of the collection of patient fluids can be described as "acute peripancreatic collections", "acute necrotic collections", "pseudocyst" and "necrosis pancreatic walled or isolated". Conclusion: Computed tomography and magnetic resonance represent the best techniques with sequential images available for diagnosis. Standardization of the terminology is critical and should improve the management of patients with multiple professionals care, risk stratification and adequate treatment. PMID:27759788

  7. Atlanta Centennial Olympic Games and Paralympic Games event study, 1996. Final report, July 1996--August 1996

    SciTech Connect

    Amodei, R.; Bard, E.; Brong, B.; Cahoon, F.; Jasper, K.

    1998-11-01

    The Atlanta metropolitan region was the location of one of the most ambitious Intelligent Transportation Systems (ITS) deployments in the United States. This deployment included several individual projects--a Central Transportation Management Center (TMC), six Traffic Control Centers (TCCs), one Transit Information Center (TIC), The Travel Information Showcase (TIS), and the extension of the Metropolitan Atlanta Rapid Transit Authority (MARTA) Rail network and the new high-occupancy vehicle (HOV) lanes on I-85 and I-75. The 1996 Atlanta Centennial Olympic Games and Paralympic Games created a focus for these projects. All of these systems were to be brought on-line in time for the Olympic Games. This report presents the findings of the 1996 Olympic and Paralympic Games Events Study--a compilation of findings of system performance, the benefits realized, and the lessons learned during their operations over the event period. The study assessed the performance of the various Travel Demand Management (TDM) plans employed for Olympic Games traffic management.

  8. Increasing spatiotemporal resolution of several major pollutant species in the Atlanta Metropolitan Area

    NASA Astrophysics Data System (ADS)

    Brosius, A. L.; Luong, K. Y.

    2014-12-01

    The American Lung Association cited Atlanta, Georgia, as one of the top 20 most polluted U.S. cities in 2014. Heavy air and ground transportation traffic contribute to the production of carbon dioxide (CO2), particulate matter (PM), and tropospheric ozone (O3) for the Atlanta Metropolitan Area (AMA). Hartsfield-Jackson Atlanta International Airport contributes significantly to the emission of these pollutants and their precursors. This study focuses on enhancing spatiotemporal resolution of CO2, PM, and O3in near-surface (ground to 50m) air columns by using Arduino-based sensors. The city of Decatur, due to its proximity to the airport, is the study site for the investigation of target pollutant concentrations. The results of this study, combined with other metropolitan air quality data sets, can be used to verify projected trends and append seasonal data. An understanding of the pollutant concentration distributions throughout the near-surface air column is vital to providing insight into the fluctuation of urban area pollutants.

  9. Minutes of the Tank Waste Science Panel meeting July 9--1, 1991. Hanford Tank Safety Project

    SciTech Connect

    Strachan, D.M.

    1992-04-01

    The fifth meeting of the Tank Waste Science Panel was held July 9--11, 1991, in Atlanta, Georgia. The subject areas included the generation, retention, and release of gases from Tank 241-SY-101 and the chemistry of ferrocyanide wastes.

  10. Characterization of aerosol composition and sources in the greater Atlanta area by aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Ng, N. L.; Xu, L.; Suresh, S.; Weber, R. J. J.; Baumann, K.; Edgerton, E. S.

    2014-12-01

    An important and uncertain aspect of biogenic secondary organic aerosol (SOA) formation is that it is often associated with anthropogenic pollution tracers. Prior studies in Atlanta suggested that 70-80% of the carbon in water-soluble organic carbon (WSOC) is modern, yet it is well-correlated with the anthropogenic CO. In this study, we deployed a High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and an Aerosol Chemical Speciation Monitor (ACSM) at multiple sites in different seasons (May 2012-February 2013) to characterize the sources and chemical composition of aerosols in the greater Atlanta area. This area in the SE US is ideal to investigate anthropogenic-biogenic interactions due to high natural and anthropogenic emissions. These extensive field studies are part of the Southeastern Center for Air Pollution and Epidemiology study (SCAPE). The HR-ToF-AMS is deployed at four sites (~ 3 weeks each) in rotation: Jefferson Street (urban), Yorkville (rural), roadside site (near Highway 75/85), and Georgia Tech site (campus), with the urban and rural sites being part of the SEARCH network. We obtained seven HR-ToF-AMS datasets in total. During the entire measurement period, the ACSM is stationary at the GIT site and samples continuously. We perform positive matrix factorization (PMF) analysis on the HR-ToF-AMS and ACSM data to deconvolve the OA into different components. While the diurnal cycle of the total OA is flat as what have been previously observed, the OA factors resolved by PMF analysis show distinctively different diurnal trends. We find that the "more-oxidized oxygenated OA" (MO-OOA) constitutes a major fraction of OA at all sites. In summer, OA is dominated by SOA, e.g., isoprene-OA and OOA with different degrees of oxidation. In contrary, biomass burning OA is more prominent in winter data. By comparing HR-ToF-AMS and ACSM data during the same sampling periods, we find that the aerosol time series are highly correlated, indicating the

  11. 77 FR 43806 - Foreign-Trade Zone 26-Atlanta, GA; Application for Reorganization (Expansion of Service Area...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-26

    ... on January 17, 1977 (Board Order 115, 42 FR 4186, 01/24/77) and reorganized under the ASF on November 26, 2010 (Board Order 1725, 75 FR 76953, 12/10/10). The zone project currently has a service area..., Pickens, Gilmer, Walker, Whitfield, Murray, Forsyth, Dawson, Hall, Banks, Lumpkin, Fulton,...

  12. Fracture mechanics; Proceedings of the 22nd National Symposium, Atlanta, GA, June 26-28, 1990. Vols. 1 & 2

    NASA Technical Reports Server (NTRS)

    Ernst, Hugo A. (Editor); Saxena, Ashok (Editor); Mcdowell, David L. (Editor); Atluri, Satya N. (Editor); Newman, James C., Jr. (Editor); Raju, Ivatury S. (Editor); Epstein, Jonathan S. (Editor)

    1992-01-01

    Current research on fracture mechanics is reviewed, focusing on ductile fracture; high-temperature and time-dependent fracture; 3D problems; interface fracture; microstructural aspects of fatigue and fracture; and fracture predictions and applications. Particular attention is given to the determination and comparison of crack resistance curves from wide plates and fracture mechanics specimens; a relationship between R-curves in contained and uncontained yield; the creep crack growth behavior of titanium alloy Ti-6242; a crack growth response in three heat resistant materials at elevated temperature; a crack-surface-contact model for determining effective-stress-intensity factors; interfacial dislocations in anisotropic bimaterials; an effect of intergranular crack branching on fracture toughness evaluation; the fracture toughness behavior of exservice chromium-molybdenum steels; the application of fracture mechanics to assess the significance of proof loading; and a load ratio method for estimating crack extension.

  13. 1988 American Control Conference, 7th, Atlanta, GA, June 15-17, 1988, Proceedings. Volumes 1, 2, and 3

    SciTech Connect

    Not Available

    1988-01-01

    Various papers on control are presented. The general topics considered include: simulation and computational methods; linear systems and control; control of flexible structures; intelligent control systems; industrial control systems; computer-aided control engineering; robust adaptive control; frequency-domain methods; filtering, estimation, and tracking; optimization of discrete event systems; trajectory control of robot manipulators; digital signal processsing in process control; control of batch processes; robustness of state space models; stable factorization; aircraft and spacecraft guidance; model order reduction; computer networking of real-time control; and advances in automatic control education. Also addressed are: implementation of adaptive and self-tuning controls in machining, eigenvalue/eigenstructure assignment, robust nonlinear control of manipulators, redundant robot control, fault detection, ACES control theory and verification, decentralized control, damage-tolerant flight control systems, neural networks in control, distributed parameter and time-delay systems, and robust stabilization and control.

  14. Symposium on Electromagnetic Windows, 19th, Georgia Institute of Technology, Atlanta, GA, Sept. 7-9, 1988, Proceedings. Volume 1

    NASA Astrophysics Data System (ADS)

    Handley, J. C.

    The present conference on EM-window technologies discusses the electrical analysis of fenestrated radomes by means of array and reaction-surface integration methods, a spherical-wave point dipole source array technique for radome analysis, a hybrid FEM/boundary-element analysis for a radome/phased-array antenna, the impedance-matching of dielectric space-frame radomes, sidewall reflections in missile radomes, the high Mach number structural performance of radomes, and athermal window materials. Also discussed are CVD-produced erosion-resistant EM windows, polyethylene fibers for use in ballistically resistant radomes, lanthana-strengthened yttria IR windows, coordinate transforms for two-axis gimbals and gimballed radome test fixtures, slip-cast fused silica rain damage, measurement of near-field radome anomalies, and open-resonator measurements of dielectric sandwich panels.

  15. Ligand "Brackets" for Ga-Ga Bond.

    PubMed

    Fedushkin, Igor L; Skatova, Alexandra A; Dodonov, Vladimir A; Yang, Xiao-Juan; Chudakova, Valentina A; Piskunov, Alexander V; Demeshko, Serhiy; Baranov, Evgeny V

    2016-09-01

    The reactivity of digallane (dpp-Bian)Ga-Ga(dpp-Bian) (1) (dpp-Bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) toward acenaphthenequinone (AcQ), sulfur dioxide, and azobenzene was investigated. The reaction of 1 with AcQ in 1:1 molar ratio proceeds via two-electron reduction of AcQ to give (dpp-Bian)Ga(μ2-AcQ)Ga(dpp-Bian) (2), in which diolate [AcQ](2-) acts as "bracket" for the Ga-Ga bond. The interaction of 1 with AcQ in 1:2 molar ratio proceeds with an oxidation of the both dpp-Bian ligands as well as of the Ga-Ga bond to give (dpp-Bian)Ga(μ2-AcQ)2Ga(dpp-Bian) (3). At 330 K in toluene complex 2 decomposes to give compounds 3 and 1. The reaction of complex 2 with atmospheric oxygen results in oxidation of a Ga-Ga bond and affords (dpp-Bian)Ga(μ2-AcQ)(μ2-O)Ga(dpp-Bian) (4). The reaction of digallane 1 with SO2 produces, depending on the ratio (1:2 or 1:4), dithionites (dpp-Bian)Ga(μ2-O2S-SO2)Ga(dpp-Bian) (5) and (dpp-Bian)Ga(μ2-O2S-SO2)2Ga(dpp-Bian) (6). In compound 5 the Ga-Ga bond is preserved and supported by dithionite dianionic bracket. In compound 6 the gallium centers are bridged by two dithionite ligands. Both 5 and 6 consist of dpp-Bian radical anionic ligands. Four-electron reduction of azobenzene with 1 mol equiv of digallane 1 leads to complex (dpp-Bian)Ga(μ2-NPh)2Ga(dpp-Bian) (7). Paramagnetic compounds 2-7 were characterized by electron spin resonance spectroscopy, and their molecular structures were established by single-crystal X-ray analysis. Magnetic behavior of compounds 2, 5, and 6 was investigated by superconducting quantum interference device technique in the range of 2-295 K. PMID:27548713

  16. Atlanta ariejansseni, a new species of shelled heteropod from the Southern Subtropical Convergence Zone (Gastropoda, Pterotracheoidea)

    PubMed Central

    Wall-Palmer, Deborah; Burridge, Alice K.; Peijnenburg, Katja T.C.A.

    2016-01-01

    Abstract The Atlantidae (shelled heteropods) is a family of microscopic aragonite shelled holoplanktonic gastropods with a wide biogeographical distribution in tropical, sub-tropical and temperate waters. The aragonite shell and surface ocean habitat of the atlantids makes them particularly susceptible to ocean acidification and ocean warming, and atlantids are likely to be useful indicators of these changes. However, we still lack fundamental information on their taxonomy and biogeography, which is essential for monitoring the effects of a changing ocean. Integrated morphological and molecular approaches to taxonomy have been employed to improve the assessment of species boundaries, which give a more accurate picture of species distributions. Here a new species of atlantid heteropod is described based on shell morphology, DNA barcoding of the Cytochrome Oxidase I gene, and biogeography. All specimens of Atlanta ariejansseni sp. n. were collected from the Southern Subtropical Convergence Zone of the Atlantic and Indo-Pacific oceans suggesting that this species has a very narrow latitudinal distribution (37–48°S). Atlanta ariejansseni sp. n. was found to be relatively abundant (up to 2.3 specimens per 1000 m3 water) within this narrow latitudinal range, implying that this species has adapted to the specific conditions of the Southern Subtropical Convergence Zone and has a high tolerance to the varying ocean parameters in this region. PMID:27551204

  17. Using synoptic weather types to predict visitor attendance at Atlanta and Indianapolis zoological parks

    NASA Astrophysics Data System (ADS)

    Perkins, David R.

    2016-02-01

    Defining an ideal "tourism climate" has been an often-visited research topic where explanations have evolved from global- to location-specific indices tailored to tourists' recreational behavior. Unfortunately, as indices become increasingly specific, they are less translatable across geographies because they may only apply to specific activities, locales, climates, or populations. A key need in the future development of weather and climate indices for tourism has been a translatable, meteorologically based index capturing the generalized ambient atmospheric conditions yet considering local climatology. To address this need, this paper tests the applicability of the spatial synoptic classification (SSC) as a tool to predict visitor attendance response in the tourism, recreation, and leisure (TRL) sector across different climate regimes. Daily attendance data is paired with the prevailing synoptic weather condition at Atlanta and Indianapolis zoological parks from September 2001 to June 2011, to review potential impacts ambient atmospheric conditions may have on visitor attendances. Results indicate that "dry moderate" conditions are most associated with high levels of attendance and "moist polar" synoptic conditions are most associated with low levels of attendance at both zoological parks. Comparing visitor response at these zoo locations, visitors in Indianapolis showed lower levels of tolerance to synoptic conditions which were not "ideal." Visitors in Indianapolis also displayed more aversion to "polar" synoptic regimes while visitors in Atlanta displayed more tolerance to "moist tropical" synoptic regimes. Using a comprehensive atmospheric measure such as the SSC may be a key to broadening application when assessing tourism climates across diverse geographies.

  18. Socio-demographic Differences in Toxic Release Inventory Siting and Emissions in Metro Atlanta

    PubMed Central

    Johnson, Ryan; Ramsey-White, Kim; Fuller, Christina H.

    2016-01-01

    Prior research has found that low socioeconomic status (SES) populations and minorities in some areas reside in communities with disproportionate exposure to hazardous chemicals. The objectives of this study were to evaluate the relevance of socio-demographic characteristics on the presence of Toxic Release Inventory (TRI) facilities, air releases, and prevalence and resolution of air quality complaints in the 20-county Atlanta Metropolitan Statistical Area (MSA). We found that there were 4.7% more minority residents in census tracts where TRI facilities were located. The odds ratio (OR) for the presence of a TRI facility was 0.89 (p < 0.01) for each 1% increase of females with a college degree and 2.4 (p < 0.01) for households with an income of $22,000–$55,000. The estimated reduction in the amount of chemicals emitted per release associated with population of females with a college degree was 18.53 pounds (p < 0.01). Complaints took longer to resolve in census tracts with higher Hispanic populations (OR = 1.031, 95% CI: 1.010–1.054). Overall, results indicate that SES and race/ethnicity are related to TRI facility siting, releases, and complaints in the Atlanta area. These findings have not been documented previously and suggest that lower SES and non-White communities may be disproportionately exposed. PMID:27455302

  19. Socio-demographic Differences in Toxic Release Inventory Siting and Emissions in Metro Atlanta.

    PubMed

    Johnson, Ryan; Ramsey-White, Kim; Fuller, Christina H

    2016-01-01

    Prior research has found that low socioeconomic status (SES) populations and minorities in some areas reside in communities with disproportionate exposure to hazardous chemicals. The objectives of this study were to evaluate the relevance of socio-demographic characteristics on the presence of Toxic Release Inventory (TRI) facilities, air releases, and prevalence and resolution of air quality complaints in the 20-county Atlanta Metropolitan Statistical Area (MSA). We found that there were 4.7% more minority residents in census tracts where TRI facilities were located. The odds ratio (OR) for the presence of a TRI facility was 0.89 (p < 0.01) for each 1% increase of females with a college degree and 2.4 (p < 0.01) for households with an income of $22,000-$55,000. The estimated reduction in the amount of chemicals emitted per release associated with population of females with a college degree was 18.53 pounds (p < 0.01). Complaints took longer to resolve in census tracts with higher Hispanic populations (OR = 1.031, 95% CI: 1.010-1.054). Overall, results indicate that SES and race/ethnicity are related to TRI facility siting, releases, and complaints in the Atlanta area. These findings have not been documented previously and suggest that lower SES and non-White communities may be disproportionately exposed. PMID:27455302

  20. Flood-frequency relations for urban streams in metropolitan Atlanta, Georgia

    SciTech Connect

    Inman, E.J.

    1983-01-01

    A knowledge of the magnitude and frequency of floods is needed for the design of highway drainage structures, for establishing flood insurance rates, and for many other uses by urban planners and engineers. This report presents a method for estimating the magnitude and frequency of floods on small streams in the Atlanta, Georgia, metropolitan area. The Distributed Routing Rainfall-Runoff Model Version II and the US Geological Survey rainfall-runoff model were calibrated for 19 drainage basins in the Atlanta area ranging in size from 0.21 to 19.1 square miles and in impervious area from 19 to 42%. The models were used to synthesize long-term flood records for these basins. The 2- to 100-year floods were developed for each basin from these long-term flood peak records using the log-Pearson Type III distribution. Multiple-regression analysis was then used to define relations between the flood-frequency station data and certain physical basin characteristics, of which drainage area, channel slope, and measured total impervious area were found to be significant. By using these relations, with these basin characteristics, the magnitude and frequency of floods at ungaged basins can be estimated. 27 refs., 6 figs., 13 tabs.

  1. Atlanta ariejansseni, a new species of shelled heteropod from the Southern Subtropical Convergence Zone (Gastropoda, Pterotracheoidea).

    PubMed

    Wall-Palmer, Deborah; Burridge, Alice K; Peijnenburg, Katja T C A

    2016-01-01

    The Atlantidae (shelled heteropods) is a family of microscopic aragonite shelled holoplanktonic gastropods with a wide biogeographical distribution in tropical, sub-tropical and temperate waters. The aragonite shell and surface ocean habitat of the atlantids makes them particularly susceptible to ocean acidification and ocean warming, and atlantids are likely to be useful indicators of these changes. However, we still lack fundamental information on their taxonomy and biogeography, which is essential for monitoring the effects of a changing ocean. Integrated morphological and molecular approaches to taxonomy have been employed to improve the assessment of species boundaries, which give a more accurate picture of species distributions. Here a new species of atlantid heteropod is described based on shell morphology, DNA barcoding of the Cytochrome Oxidase I gene, and biogeography. All specimens of Atlanta ariejansseni sp. n. were collected from the Southern Subtropical Convergence Zone of the Atlantic and Indo-Pacific oceans suggesting that this species has a very narrow latitudinal distribution (37-48°S). Atlanta ariejansseni sp. n. was found to be relatively abundant (up to 2.3 specimens per 1000 m(3) water) within this narrow latitudinal range, implying that this species has adapted to the specific conditions of the Southern Subtropical Convergence Zone and has a high tolerance to the varying ocean parameters in this region.

  2. Socio-demographic Differences in Toxic Release Inventory Siting and Emissions in Metro Atlanta.

    PubMed

    Johnson, Ryan; Ramsey-White, Kim; Fuller, Christina H

    2016-07-23

    Prior research has found that low socioeconomic status (SES) populations and minorities in some areas reside in communities with disproportionate exposure to hazardous chemicals. The objectives of this study were to evaluate the relevance of socio-demographic characteristics on the presence of Toxic Release Inventory (TRI) facilities, air releases, and prevalence and resolution of air quality complaints in the 20-county Atlanta Metropolitan Statistical Area (MSA). We found that there were 4.7% more minority residents in census tracts where TRI facilities were located. The odds ratio (OR) for the presence of a TRI facility was 0.89 (p < 0.01) for each 1% increase of females with a college degree and 2.4 (p < 0.01) for households with an income of $22,000-$55,000. The estimated reduction in the amount of chemicals emitted per release associated with population of females with a college degree was 18.53 pounds (p < 0.01). Complaints took longer to resolve in census tracts with higher Hispanic populations (OR = 1.031, 95% CI: 1.010-1.054). Overall, results indicate that SES and race/ethnicity are related to TRI facility siting, releases, and complaints in the Atlanta area. These findings have not been documented previously and suggest that lower SES and non-White communities may be disproportionately exposed.

  3. Atlanta ariejansseni, a new species of shelled heteropod from the Southern Subtropical Convergence Zone (Gastropoda, Pterotracheoidea).

    PubMed

    Wall-Palmer, Deborah; Burridge, Alice K; Peijnenburg, Katja T C A

    2016-01-01

    The Atlantidae (shelled heteropods) is a family of microscopic aragonite shelled holoplanktonic gastropods with a wide biogeographical distribution in tropical, sub-tropical and temperate waters. The aragonite shell and surface ocean habitat of the atlantids makes them particularly susceptible to ocean acidification and ocean warming, and atlantids are likely to be useful indicators of these changes. However, we still lack fundamental information on their taxonomy and biogeography, which is essential for monitoring the effects of a changing ocean. Integrated morphological and molecular approaches to taxonomy have been employed to improve the assessment of species boundaries, which give a more accurate picture of species distributions. Here a new species of atlantid heteropod is described based on shell morphology, DNA barcoding of the Cytochrome Oxidase I gene, and biogeography. All specimens of Atlanta ariejansseni sp. n. were collected from the Southern Subtropical Convergence Zone of the Atlantic and Indo-Pacific oceans suggesting that this species has a very narrow latitudinal distribution (37-48°S). Atlanta ariejansseni sp. n. was found to be relatively abundant (up to 2.3 specimens per 1000 m(3) water) within this narrow latitudinal range, implying that this species has adapted to the specific conditions of the Southern Subtropical Convergence Zone and has a high tolerance to the varying ocean parameters in this region. PMID:27551204

  4. Georgia State University Spending Patterns and the Atlanta Economy, 1983. Institutional Research Report No. 84-2.

    ERIC Educational Resources Information Center

    Posey, Ellen I.

    The economic impact of Georgia State University on Atlanta was assessed. The survey methodology of Salley (1976) was employed, and the differential expenditure multiplier was recomputed using local value added data. Attention was directed to: university enrollment, payroll, and spending; estimated student and staff spending; calculation of the…

  5. Impact of Postcensal Versus Intercensal Population Estimates on Prevalence of Selected Developmental Disabilities--Metropolitan Atlanta, Georgia, 1991-1996

    ERIC Educational Resources Information Center

    Lazarus, Carrie; Autry, Andy; Baio, Jon; Avchen, Rachel Nonkin; Braun, Kim Van Nardeen

    2007-01-01

    Prevalence estimates often use U.S. Census Bureau estimates of the population as denominator data. Postcensal estimates are population estimates produced following a decennial census. Intercensal estimates are surrounded by 2 census years and supersede postcensal estimates. In this report we describe prevalence estimates in Atlanta for mental…

  6. Georgia State University Spending Patterns and the Atlanta Economy, 1989. Institutional Research Report No. 90-24.

    ERIC Educational Resources Information Center

    Posey, Ellen I.

    This study sought to provide an up-to-date picture of the substantial dividend of jobs and income which Georgia State University provides to the Atlanta area. The study proceeded in six phases: (1) collection of direct university enrollment, payroll, and spending data; (2) survey and estimation of student spending; (3) survey and estimation of…

  7. The Nation's Report Card Reading 2009 Trial Urban District Snapshot Report. Atlanta Public Schools. Grade 4, Public Schools

    ERIC Educational Resources Information Center

    National Center for Education Statistics, 2010

    2010-01-01

    Each district that participated in the National Assessment of Educational Progress (NAEP) 2009 Trial Urban District Assessment in reading receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Atlanta Public Schools' student achievement in reading. In 2009, the average…

  8. The Nation's Report Card Reading 2009 Trial Urban District Snapshot Report. Atlanta Public Schools. Grade 8, Public Schools

    ERIC Educational Resources Information Center

    National Center for Education Statistics, 2010

    2010-01-01

    Each district that participated in the National Assessment of Educational Progress (NAEP) 2009 Trial Urban District Assessment in reading receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Atlanta Public Schools' student achievement in reading. In 2009, the average…

  9. Teacher Morale in the Atlanta Public Schools: Spring 1990. Report No. 4, Volume 25, 11/91.

    ERIC Educational Resources Information Center

    Fraser, Lowrie A.

    A study was done of Atlanta (Georgia) public school teacher morale in May of 1990. About 40 percent of the teaching staff (1,520 teachers) voluntarily completed a 91-item questionnaire that contained subsets of questions from the Maslach Burnout Inventory and three subscales of emotional exhaustion, departmentalization, and personal…

  10. Atlanta Public Schools' 1980 Achievement Testing Program: A Year of Test Adoption. Report No. 16-4.

    ERIC Educational Resources Information Center

    Atlanta Public Schools, GA. Div. of Research, Evaluation, and Data Processing.

    This document reports on the procedures and results of the Atlanta Public Schools (APS) testing program in changing from the Iowa Tests of Basic Skills (ITBS), administered to grades 1 through 7 from 1973-79, to the California Achievement Tests (CAT), Form C, administered in Spring 1980 to provide a continuous testing program from the elementary…

  11. BACKGROUND MATERIALS FOR WATERSHED CENTRAL DEVELOPMENT WORKSHOP HELD JANUARY 8-10, 2007, IN ATLANTA, GEORGIA (CD)

    EPA Science Inventory

    A development workshop for Watershed Central was held in Atlanta, Georgia, January 8-10, 2007. Participants in the workshop included representatives of EPA’s Office of Water, Office of Environmental Information, Office of Research and Development, and several Regional Offices. ...

  12. Comparison of nonmethane organic compound concentration data collected by two methods in Atlanta

    SciTech Connect

    Shreffler, J.H.

    1993-12-01

    Title I of the Clean Air Act Amendments of 1990 calls for 'enhanced monitoring' of ozone, which is planned to include measurements of atmospheric non-methane organic compounds (NMOCs). NMOC concentration data gathered by two methods in Atlanta, Georgia during July and August 1990 are compared in order to assess the reliability of such measurements in an operational setting. During that period, automated gas chromatography (GC) systems (Field systems) were used to collect NMOC continuously as one-hour averages. In addition, canister samples of ambient air were collected on an intermittent schedule for quality control purposes and analyzed by laboratory GC (the Lab system). Data from the six-site network included concentrations of nitrogen oxides (NOx), carbon monoxide (CO), ozone, total NMOC (TNMOVC), and 47 identified NMOCs. (Copyright (c) 1993-Air Waste Management Association.)

  13. Flood-flow characteristics of Nancy Creek at Georgia Highway 400 extension near Atlanta, Georgia

    USGS Publications Warehouse

    Price, McGlone; Hess, Glen W.

    1987-01-01

    The Highway Division, Georgia Department of Transportation, plans the extension of Georgia Highway 400 from Interstate 285 southward to Interstate 85. As part of this extension, the Highway Division plans construction of a bridge crossing Nancy Creek near Atlanta, Georgia. The U.S. Geological Survey, in cooperation with the Highway Division, determined the flood flow characteristics of Nancy Creek near the bridge crossing. The flood frequency, elevation discharge relation, flood profiles, floodway, and flood flow effects were determined. The maximum backwater effect for the proposed bridge and relocated channel was 0.2 ft for the 100-yr flood. The relocated channel will drastically shorten flow length near the proposed State Highway 400 extension and reduce the 100-yr flood elevation between one and two ft from existing conditions between the proposed site and Windsor Parkway. (Author 's abstract)

  14. Health and Environment Linked for Information Exchange (HELIX)-Atlanta: A CDC-NASA Joint Environmental Public Health Tracking Collaborative Project

    NASA Technical Reports Server (NTRS)

    Al-Hamdan, Mohammad; Luvall, Jeff; Crosson, Bill; Estes, Maury; Limaye, Ashutosh; Quattrochi, Dale; Rickman, Doug

    2008-01-01

    HELIX-Atlanta was developed to support current and future state and local EPHT programs to implement data linking demonstration projects which could be part of the CDC EPHT Network. HELIX-Atlanta is a pilot linking project in Atlanta for CDC to learn about the challenges the states will encounter. NASA/MSFC and the CDC are partners in linking environmental and health data to enhance public health surveillance. The use of NASA technology creates value added geospatial products from existing environmental data sources to facilitate public health linkages. Proving the feasibility of the approach is the main objective

  15. Remote Sensing of Atlanta's Urban Sprawl and the Distribution of Land Cover and Surface Temperatures

    NASA Technical Reports Server (NTRS)

    Laymon, Charles A.; Estes, Maurice G., Jr.; Quattrochi, Dale A.; Arnold, James E. (Technical Monitor)

    2001-01-01

    Between 1973 and 1992, an average of 20 ha of forest was lost each day to urban expansion of Atlanta, Georgia. Urban surfaces have very different thermal properties than natural surfaces-storing solar energy throughout the day and continuing to release it as sensible heat well after sunset. The resulting heat island effect serves as catalysts for chemical reactions from vehicular exhaust and industrialization leading to a deterioration in air quality. In this study, high spatial resolution multispectral remote sensing data has been used to characterize the type, thermal properties, and distribution of land surface materials throughout the Atlanta metropolitan area. Ten-meter data were acquired with the Advanced Thermal and Land Applications Sensor (ATLAS) on May 11 and 12, 1997. ATLAS is a 15-channel multispectral scanner that incorporates the Landsat TM bands with additional bands in the middle reflective infrared and thermal infrared range. The high spatial resolution permitted discrimination of discrete surface types (e.g., concrete, asphalt), individual structures (e.g., buildings, houses) and their associated thermal characteristics. There is a strong temperature contrast between vegetation and anthropomorphic features. Vegetation has a modal temperature at about 20 C, whereas asphalt shingles, pavement, and buildings have a modal temperature of about 39 C. Broad-leaf vegetation classes are indistinguishable on a thermal basis alone. There is slightly more variability (plus or minus 5 C) among the urban surfaces. Grasses, mixed vegetation and mixed urban surfaces are intermediate in temperature and are characterized by broader temperature distributions with modes of about 29 C. Thermal maps serve as a basis for understanding the distribution of "hotspots", i.e., how landscape features and urban fabric contribute the most heat to the lower atmosphere.

  16. Remote Sensing of Atlanta's Urban Sprawl and the Distribution of Land Cover and Surface Temperature

    NASA Technical Reports Server (NTRS)

    Laymon, Charles A.; Estes, Maurice G., Jr.; Quattrochi, Dale A.; Goodman, H. Michael (Technical Monitor)

    2001-01-01

    Between 1973 and 1992, an average of 20 ha of forest was lost each day to urban expansion of Atlanta, Georgia. Urban surfaces have very different thermal properties than natural surfaces-storing solar energy throughout the day and continuing to release it as sensible heat well after sunset. The resulting heat island effect serves as catalysts for chemical reactions from vehicular exhaust and industrialization leading to a deterioration in air quality. In this study, high spatial resolution multispectral remote sensing data has been used to characterize the type, thermal properties, and distribution of land surface materials throughout the Atlanta metropolitan area. Ten-meter data were acquired with the Advanced Thermal and Land Applications Sensor (ATLAS) on May 11 and 12, 1997. ATLAS is a 15-channel multispectral scanner that incorporates the Landsat TM bands with additional bands in the middle reflective infrared and thermal infrared range. The high spatial resolution permitted discrimination of discrete surface types (e.g., concrete, asphalt), individual structures (e.g., buildings, houses) and their associated thermal characteristics. There is a strong temperature contrast between vegetation and anthropomorphic features. Vegetation has a modal temperature at about 20 C, whereas asphalt shingles, pavement, and buildings have a modal temperature of about 39 C. Broad-leaf vegetation classes are indistinguishable on a thermal basis alone. There is slightly more variability (+/-5 C) among the urban surfaces. Grasses, mixed vegetation and mixed urban surfaces are intermediate in temperature and are characterized by broader temperature distributions with modes of about 29 C. Thermal maps serve as a basis for understanding the distribution of "hotspots", i.e., how landscape features and urban fabric contribute the most heat to the lower atmosphere.

  17. HIV Risk Behaviors, Perceptions, and Testing and Preexposure Prophylaxis (PrEP) Awareness/Use in Grindr-Using Men Who Have Sex With Men in Atlanta, Georgia.

    PubMed

    Goedel, William C; Halkitis, Perry N; Greene, Richard E; Hickson, DeMarc A; Duncan, Dustin T

    2016-01-01

    Geosocial-networking smartphone applications such as Grindr can help men who have sex with men (MSM) meet sexual partners. Given the high incidence of HIV in the Deep South, the purpose of our study was to assess HIV risk and preexposure prophylaxis (PrEP) awareness and use in a sample of HIV-uninfected, Grindr-using MSM residing in Atlanta, Georgia (n = 84). Most (n = 71; 84.6%) reported being somewhat or very concerned about becoming HIV infected. Most (n = 74; 88.1%) had been tested for HIV in their lifetimes. About three fourths (n = 65; 77.4%) were aware of PrEP, but only 11.9% currently used the medication. HIV continues to disproportionately impact MSM and represents a significant source of concern. As the number of new infections continues to rise, it is important to decrease risks associated with acquisition and transmission of HIV by increasing rates of HIV testing and the use of biobehavioral interventions such as PrEP. PMID:26708834

  18. HIV Risk Behaviors, Perceptions, and Testing and Preexposure Prophylaxis (PrEP) Awareness/Use in Grindr-Using Men Who Have Sex With Men in Atlanta, Georgia.

    PubMed

    Goedel, William C; Halkitis, Perry N; Greene, Richard E; Hickson, DeMarc A; Duncan, Dustin T

    2016-01-01

    Geosocial-networking smartphone applications such as Grindr can help men who have sex with men (MSM) meet sexual partners. Given the high incidence of HIV in the Deep South, the purpose of our study was to assess HIV risk and preexposure prophylaxis (PrEP) awareness and use in a sample of HIV-uninfected, Grindr-using MSM residing in Atlanta, Georgia (n = 84). Most (n = 71; 84.6%) reported being somewhat or very concerned about becoming HIV infected. Most (n = 74; 88.1%) had been tested for HIV in their lifetimes. About three fourths (n = 65; 77.4%) were aware of PrEP, but only 11.9% currently used the medication. HIV continues to disproportionately impact MSM and represents a significant source of concern. As the number of new infections continues to rise, it is important to decrease risks associated with acquisition and transmission of HIV by increasing rates of HIV testing and the use of biobehavioral interventions such as PrEP.

  19. High Spatial Resolution Thermal Infrared Remote Sensing Data for Analysis of the Atlanta, Georgia, Urban Heat Island Effect and Its Impacts on the Environment

    NASA Technical Reports Server (NTRS)

    Quattrochi, Dale A.

    2007-01-01

    The twenty-first century is the first "urban century" according to the United Nations Development Program. The focus of cities reflects awareness of the growing percentage of the world's population that lives in urban areas. In environmental terms, cities are the original producers of many of the global problems related to waste disposal, air and water pollution, and associated environmental and ecological challenges. Expansion of cities, both in population and areal extent, is a relentless process. In 2000, approximately 3 billion people representing about 40% of the global population, resided in urban areas. Urban population will continue to rise substantially over the next several decades according to UN estimates, and most of this growth will Occur in developing countries. The UN estimates that by 2025, 60% of the world's population will live in urban areas. As a consequence, the number of"megacities" (those cities with populations of 10 million inhabitants or more) will increase by 100 by 2025. Thus, there is a critical need to understand urban areas and what their impacts are on environmental, ecological and hydrologic resources, as well as on the local, regional, and even global climate. One of the more egregious side effects of urbanization is the increase in surface and air temperatures that lead to deterioration in air quality. In the United States, under the more stringent air quality guidelines established by the U.S. Environmental Protection Agency in 1997, nearly 300 counties in 34 states will not meet these new air quality standards for ground level ozone. Mitigation of the urban heat island (UHI) effect is actively being evaluated as a possible way to reduce ground ozone levels in cities and assist states in improving air quality. Foremost in the analysis of how the UHI affects air quality and other environmental factors is the use of remote sensing technology and data to characterize urban land covers in sufficient detail to quantifiably measure

  20. Making it pay in Athens, GA

    SciTech Connect

    Malloy, M.G.

    1997-04-01

    The materials recovery facility (MRF) in Athens, GA, is a well-fed recycling facility. But, if the local government has its way, it will be even better fed in the near future. The Athens-Clarke County (ACC) regional municipality in which the facility resides has a put-or-pay contract with the plant`s owner/operator, under which the more it feeds the MRF, the more money it receives in return, through the sale of recycled end products. The ACC Solid Waste Department uses a volume-based waste collection system that encourages residents to recycle--the more they recycle, the less trash they have to put out, and the less they pay each month. The Athens facility, which will be a featured site tour at next month`s WasteExpo `97 in nearby Atlanta, had its ground-breaking two years ago, in April 1995. ACC is responsible for delivering material--or seeing that recyclables are delivered--to the MRF, which is owned and operated by Resource Recovery Systems (RRS, Centerbrook, Conn.). Over the past year, ACC has stepped up various incentives for businesses to recycle and send their recyclables to the facility, including instituting pilot programs for commercial interests that offer them versions of volume-based collection similar to that done by residents.

  1. Intercomparison of an Aerosol Chemical Speciation Monitor (ACSM) with ambient fine aerosol measurements in Downtown Atlanta, Georgia

    NASA Astrophysics Data System (ADS)

    Budisulistiorini, S. H.; Canagaratna, M. R.; Croteau, P. L.; Baumann, K.; Edgerton, E. S.; Kollman, M. S.; Ng, N. L.; Verma, V.; Shaw, S. L.; Knipping, E. M.; Worsnop, D. R.; Jayne, J. T.; Weber, R. J.; Surratt, J. D.

    2013-12-01

    The Aerodyne Aerosol Chemical Speciation Monitor (ACSM) was recently developed to provide long-term real-time continuous measurements of ambient non-refractory (i.e., organic, sulfate, ammonium, nitrate, and chloride) submicron particulate matter (NR-PM1). Currently, there are a limited number of field studies that evaluate the long-term performance of the ACSM against established monitoring networks. In this study, we present seasonal intercomparisons of the ACSM with collocated fine aerosol (PM2.5) measurements at the Southeastern Aerosol Research and Characterization (SEARCH) Jefferson Street (JST) site near downtown Atlanta, GA, during 2011-2012. The collocated measurements included a second ACSM, continuous and integrated sulfate, nitrate, and ammonium measurements, as well as a semi-continuous Sunset organic carbon/elemental carbon (OC/EC) analyzer, continuous tapered element oscillating microbalance (TEOM), 24 h integrated Federal Reference Method (FRM) filters, and continuous scanning electrical mobility system-mixing condensation particle counter (SEMS-MCPC). Intercomparison of the two collocated ACSMs resulted in strong correlations (r2 > 0.8) for all chemical species, except chloride (r2 = 0.21); mass concentration for all chemical species agreed within ±27%, indicating that ACSM instruments are capable of stable and reproducible operation. Chemical constituents measured by the ACSM are also compared with those obtained from the continuous measurements from JST. Since the continuous measurement concentrations are adjusted to match the integrated filter measurements, these comparisons reflect the combined uncertainties of the ACSM, continuous, and filter measurements. In general, speciated ACSM mass concentrations correlate well (r2 > 0.7) with the continuous measurements from JST, although the correlation for nitrate is weaker (r2 = 0.55) in summer. Differences between ACSM mass concentrations and the filter-adjusted JST continuous data are 5-27%, 4

  2. AERA Vocational Education Special Interest Group Proceedings. American Educational Research Association Annual Meeting (Atlanta, Georgia, April 12-16, 1993).

    ERIC Educational Resources Information Center

    Redmann, Donna H., Ed.

    This conference report contains the following 18 papers: "State Policies and State Vocational Education Director Perceptions Pertinent to Career-oriented Education in the Middle Grades" (Barrick, Hughes); "Complying with Perkins: Using Existing Tests To Measure Academic Gains for Vocational Education Students" (Bergstrom, Gershon); "Teachers'…

  3. Preventing the repetition: Or, what Los Angeles' experience in water management can teach Atlanta about urban water disputes

    NASA Astrophysics Data System (ADS)

    Feldman, David L.

    2009-04-01

    Southern California's water history is an epic story with larger-than-life characters and ambitions and abundant hubris. Students of water policy might reasonably ask: Does this story, while unique to greater Los Angeles, hold lessons for other metropolises experiencing water conflict caused by explosive growth? We examine this question by considering similarities between the challenges facing Atlanta, Georgia, one of the nation's fastest growing cities in the 21st century, with those of Los Angeles. We focus on junctures where important decisions regarding water were made and how these decisions continue to challenge both cities' futures. Atlanta's financial, cultural, and environmental imprint on its surrounding region share remarkable similarities with Los Angeles' influence trajectory: it is the largest city in the southeast, a principal transportation and business hub, and it is embroiled in water conflict with nearby communities and adjoining states.

  4. The Effect of Commuting Patterns on HIV Care Attendance Among Men Who Have Sex With Men (MSM) in Atlanta, Georgia

    PubMed Central

    Kramer, Michael R; Rosenberg, Eli S; Sanchez, Travis H; Reed, Landon; Sullivan, Patrick S

    2015-01-01

    Background Travel-related barriers to human immunodeficiency virus (HIV) care, such as commute time and mode of transportation, have been reported in the United States. Objective The objective of the study was to investigate the association between public transportation use and HIV care attendance among a convenience sample of Atlanta-based, HIV-positive men who have sex with men (MSM), evaluate differences across regions of residence, and estimate the relationship between travel distance and time by mode of transportation taken to attend appointments. Methods We used Poisson regression to estimate the association between use of public transportation to attend HIV-related medical visits and frequency of care attendance over the previous 12 months. The relationship between travel distance and commute time was estimated using linear regression. Kriging was used to interpolate commute time to visually examine geographic differences in commuting patterns in relation to access to public transportation and population-based estimates of household vehicle ownership. Results Using public transportation was associated with lower rates of HIV care attendance compared to using private transportation, but only in south Atlanta (south: aRR: 0.75, 95% CI 0.56, 1.0, north: aRR: 0.90, 95% CI 0.71, 1.1). Participants living in south Atlanta were more likely to have longer commute times associated with attending HIV visits, have greater access to public transportation, and may live in areas with low vehicle ownership. A majority of attended HIV providers were located in north and central Atlanta, despite there being participants living all across the city. Estimated commute times per mile traveled were three times as high among public transit users compared to private transportation users. Conclusions Improving local public transit and implementing use of mobile clinics could help address travel-related barriers to HIV care. PMID:27227128

  5. Effects of urbanization on streamflow in the Atlanta area (Georgia, USA): A comparative hydrological approach

    USGS Publications Warehouse

    Rose, S.; Peters, N.E.

    2001-01-01

    For the period from 1958 to 1996, streamflow characteristics of a highly urbanized watershed were compared with less-urbanized and non-urbanized watersheds within a 20 000 km2 region in the vicinity of Atlanta, Georgia: In the Piedmont and Blue Ridge physiographic provinces of the southeastern USA. Water levels in several wells completed in surficial and crystalline-rock aquifers were also evaluated. Data were analysed for seven US Geological Survey (USGS) stream gauges, 17 National Weather Service rain gauges, and five USGS monitoring wells. Annual runoff coefficients (RCs; runoff as a fractional percentage of precipitation) for the urban stream (Peachtree Creek) were not significantly greater than for the less-urbanized watersheds. The RCs for some streams were similar to others and the similar streams were grouped according to location. The RCs decreased from the higher elevation and higher relief watersheds to the lower elevation and lower relief watersheds: Values were 0.54 for the two Blue Ridge streams. 0.37 for the four middle Piedmont streams (near Atlanta), and 0.28 for a southern Piedmont stream. For the 25 largest stormflows, the peak flows for Peachtree Creek were 30% to 100% greater then peak flows for the other stream. The storm recession period for the urban stream was 1-2 days less than that for the other streams and the recession was characterized by a 2-day storm recession constant that was, on average, 40 to 100% greater, i.e. streamflow decreased more rapidly than for the other streams. Baseflow recession constants ranged from 35 to 40% lower for Peachtree Creek than for the other streams; this is attributed to lower evapotranspiration losses, which result in a smaller change in groundwater storage than in the less-urbanized watersheds. Low flow of Peachtree Creek ranged from 25 to 35% less than the other streams, possibly the result of decreased infiltration caused by the more efficient routing of stormwater and the paving of groundwater

  6. Volatility and Hygroscopicity of Atlanta CCN During New Particle Formation Events in Summer 2009

    NASA Astrophysics Data System (ADS)

    Moore, R.; Scheckman, J.; Williams, B. J.; Jiang, J.; McMurry, P. H.; Zhao, J.; Smith, J. N.; Nenes, A.

    2011-12-01

    New particle formation (NPF) has the potential to substantially impact the population of cloud condensation nuclei (CCN) by both by altering their number concentrations and the hygroscopic properties. It is currently thought that while NPF proceeds via condensation of gas-phase sulfuric acid, subsequent growth must be dominated by the condensation of secondary organic species in order to reconcile field observations with theory1,2. This implies size-dependent aerosol composition with varying amounts of organic species, yet the impact of these organics on cloud droplet formation remains one of the largest sources of uncertainty in aerosol-cloud-climate interactions studies. Consequently, there is a need for in-situ, size-resolved field measurements of CCN to unravel these complex effects. // // We present a comprehensive characterization of aerosol and CCN sampled in Midtown Atlanta during the August 2009 Nucleation and CCN intensive campaign (NCCN) at the Jefferson Street monitoring site. A Droplet Measurement Technologies Continuous-Flow Stream-wise Thermal-Gradient Chamber was operated in spectrometer mode using Scanning Flow CCN Analysis (SFCA)3 to provide size-resolved CCN concentrations over a variety of particle sizes (20-50 nm) and supersaturations (0.3-2%) with high temporal resolution (~30 seconds/scan). Continuous measurements of the aerosol size distribution (1-1000 nm) and chemical composition were also made. The inferred hygroscopicity increased substantially during NPF from ~0.2-0.3 (consistent with soluble secondary organic species) to ~0.6-0.8, consistent with sulfate species or organic salts. This finding is contrary to previous work suggesting less-CCN-active aerosol during NPF4. During two special experiments, a volatility tandem differential mobility analyzer (VTDMA) was coupled with the CCN instrument to examine the volatility-dependence of the CCN hygroscopicity of 40-nm particles. Heating particles in the VTDMA was observed to increase their

  7. Feasibility study of social media to reduce intimate partner violence among gay men in metro atlanta, georgia.

    PubMed

    Strasser, Sheryl M; Smith, Megan; Pendrick-Denney, Danielle; Boos-Beddington, Sarah; Chen, Ken; McCarty, Frances

    2012-08-01

    Intimate Partner Violence (IPV) is a major public health issue occurring in the United States and globally. While little is known in general about IPV, understanding about the prevalence of physical IPV among gay men is even more obscure. There is a clear disparity in violence research attention focused on this vulnerable segment of society. This cross-sectional survey study was conducted to examine the feasibility of enrolling 100 gay men from Atlanta into an IPV survey study. The survey was administered via Facebook. Ninety-nine usable surveys were collected. Chi-square tests reveal that minority ethnic status, illicit drug use, and non-disclosed orientation status were all significantly associated with positive IPV reports--in terms of both victimization as well as perpetration. Overall, the majority of the study sample indicated that they believe IPV is a health problem in the Atlanta gay community. These findings bear importance for the Atlanta gay community and public health professionals who must address this nearly invisible yet increasing public health issue. PMID:22928060

  8. Feasibility Study of Social Media to Reduce Intimate Partner Violence Among Gay Men in Metro Atlanta, Georgia

    PubMed Central

    Strasser, Sheryl M; Smith, Megan; Pendrick-Denney, Danielle; Boos-Beddington, Sarah; Chen, Ken; McCarty, Frances

    2012-01-01

    Intimate Partner Violence (IPV) is a major public health issue occurring in the United States and globally. While little is known in general about IPV, understanding about the prevalence of physical IPV among gay men is even more obscure. There is a clear disparity in violence research attention focused on this vulnerable segment of society. This cross-sectional survey study was conducted to examine the feasibility of enrolling 100 gay men from Atlanta into an IPV survey study. The survey was administered via Facebook. Ninety-nine usable surveys were collected. Chi-square tests reveal that minority ethnic status, illicit drug use, and non-disclosed orientation status were all significantly associated with positive IPV reports--in terms of both victimization as well as perpetration. Overall, the majority of the study sample indicated that they believe IPV is a health problem in the Atlanta gay community. These findings bear importance for the Atlanta gay community and public health professionals who must address this nearly invisible yet increasing public health issue. PMID:22928060

  9. PAHs and PM2.5 emissions and female breast cancer incidence in metro Atlanta and rural Georgia.

    PubMed

    Parikh, Puja Vijay; Wei, Yudan

    2016-08-01

    Environmental chemical exposure could be an important etiologic factor for geographic differences in breast cancer incidence. In this study, we examined emissions of polycyclic aromatic hydrocarbons (PAHs) and PM2.5 in relation to breast cancer incidence in metro Atlanta and rural Georgia by analyzing data from the Surveillance, Epidemiology, and End Results Program and the Environmental Protection Agency. The results showed that metro Atlanta had a significantly higher age-adjusted annual incidence rate of female breast cancer than rural Georgia (132.6 vs. 113.7 per 100,000) for 1992-2011. Emissions of both PAHs [adjusted β = 0.568 (95 % CI: 0.209, 0.927); p = 0.004] and PM2.5 [adjusted β = 2.964 (95 % CI: 0.468, 5.459); p = 0.023] were significantly associated with breast cancer incidence in metro Atlanta area. This study suggests that ambient air pollution, especially PAHs and PM2.5, could have a significant impact on the increased incidence of female breast cancer in urban areas.

  10. Applying a PrEP Continuum of Care for Men Who Have Sex With Men in Atlanta, Georgia.

    PubMed

    Kelley, Colleen F; Kahle, Erin; Siegler, Aaron; Sanchez, Travis; Del Rio, Carlos; Sullivan, Patrick S; Rosenberg, Eli S

    2015-11-15

    Reductions in human immunodeficiency virus (HIV) incidence with pre-exposure prophylaxis (PrEP) for men who have sex with men (MSM) will require significant coverage of those at risk. We propose a simplified framework, similar to the HIV care continuum, to achieve protection with PrEP as follows: 1. At-risk MSM; 2. Awareness of and willingness to take PrEP; 3. Access to healthcare; 4. Receiving a prescription; and 5. Adhering to effective PrEP. We evaluated the PrEP care continuum on an Atlanta cohort of MSM and projected how many MSM might achieve protection from HIV. Even with optimistic estimates, few Atlanta MSM (15%) are projected to achieve protection from HIV with PrEP given the significant barriers described. Each continuum step represents an important point for intervention that could substantially increase the overall effectiveness of PrEP. In addition, novel strategies for PrEP delivery are needed to achieve the necessary effectiveness for Atlanta MSM at risk of HIV.

  11. NASA Low Visibility Landing and Surface Operations (LVLASO) Atlanta Demonstration: Surveillance Systems Performance Analysis

    NASA Technical Reports Server (NTRS)

    Cassell, Rick; Evers, Carl; Hicok, Dan; Lee, Derrick

    1999-01-01

    NASA conducted a series of flight experiments at Hartsfield Atlanta International Airport as part of the Low Visibility Landing and Surface Operations (LVLASO) Program. LVLASO is one of the subelements of the NASA Terminal Area Productivity (TAP) Program, which is focused on providing technology and operating procedures for achieving clear-weather airport capacity in instrument-weather conditions, while also improving safety. LVLASO is investigating various technologies to be applied to airport surface operations, including advanced flight deck displays and surveillance systems. The purpose of this report is to document the performance of the surveillance systems tested as part of the LVLASO flight experiment. There were three surveillance sensors tested: primary radar using Airport Surface Detection Equipment (ASDE-3) and the Airport Movement Area Safety System (AMASS), Multilateration using the Airport Surface Target Identification System (ATIDS), and Automatic Dependent Surveillance - Broadcast (ADS-B) operating at 1090 MHz. The performance was compared to the draft requirements of the ICAO Advanced Surface Movement Guidance and Control System (A-SMGCS). Performance parameters evaluated included coverage, position accuracy, and update rate. Each of the sensors was evaluated as a stand alone surveillance system.

  12. “Everyone called me grandma”: Public housing demolition and relocation among older adults in Atlanta

    PubMed Central

    Keene, Danya E; Ruel, Erin

    2012-01-01

    Over the last few decades public and political dissatisfaction with public housing projects and an increasing emphasis on poverty deconcentration has led to the demolition of public housing in cities across the country. A significant body of literature has examined experiences of relocation from public housing and their implications for the well-being of individuals and communities. While much of this literature has focused on young or middle-aged adults and children, older adults have also been affected by demolition and relocation. The displacement of older adults raises a new set of age and life-course specific concerns for the well-being of this population. In this paper, we analyze the relocation narratives of 25 former public housing residents in Atlanta, Georgia. Our analysis focuses on the loss of geographically rooted communities of kinship, support and belonging that many participants, particularly those who have aged in place, attribute to their former developments. Participants describe many material and psychosocial benefits associated with living in communities that were “like families” and where they often held important roles as respected elders. While some were satisfied with their moves, others describe the dispersal of these “families” as a deeply felt loss. While some were able to draw on support from children and grandchildren in their new homes, others describe experiences of profound isolation after relocation. PMID:24187415

  13. "Everyone called me grandma": Public housing demolition and relocation among older adults in Atlanta.

    PubMed

    Keene, Danya E; Ruel, Erin

    2013-01-01

    Over the last few decades public and political dissatisfaction with public housing projects and an increasing emphasis on poverty deconcentration has led to the demolition of public housing in cities across the country. A significant body of literature has examined experiences of relocation from public housing and their implications for the well-being of individuals and communities. While much of this literature has focused on young or middle-aged adults and children, older adults have also been affected by demolition and relocation. The displacement of older adults raises a new set of age and life-course specific concerns for the well-being of this population. In this paper, we analyze the relocation narratives of 25 former public housing residents in Atlanta, Georgia. Our analysis focuses on the loss of geographically rooted communities of kinship, support and belonging that many participants, particularly those who have aged in place, attribute to their former developments. Participants describe many material and psychosocial benefits associated with living in communities that were "like families" and where they often held important roles as respected elders. While some were satisfied with their moves, others describe the dispersal of these "families" as a deeply felt loss. While some were able to draw on support from children and grandchildren in their new homes, others describe experiences of profound isolation after relocation.

  14. Multilevel Factors Influencing Hepatitis B Screening and Vaccination among Vietnamese Americans in Atlanta, Georgia

    PubMed Central

    Frew, Paula M.; Alhanti, Brooke; Vo-Green, Linda; Zhang, Siyu; Liu, Chang; Nguyen, Tranh; Schamel, Jay; Saint-Victor, Diane S.; Nguyen, Minh Ly

    2014-01-01

    Chronic hepatitis B virus (HBV) infection may lead to liver cirrhosis, chronic liver disease, and liver cancer. Immunization rates are suboptimal among Asian Americans/Pacific Islanders (AAPIs), who remain disproportionately affected by these illnesses. We investigated socioecological factors affecting HBV prevention among 316 Vietnamese Americans in Atlanta, Georgia. Social and community support of HBV vaccination was associated with screening (OR=1.69, 95% CI [1.21,2.38]), vaccination (OR=1.89, [1.27,2.81]), and intent to vaccinate (OR=1.77, [1.13,2.78]). Misconceptions decreased screening likelihood (OR=0.67, [0.46,0.99]) and vaccination (OR=0.55, [0.35,0.86]). Those able to pay for medical treatment (OR=1.23, [1.01,1.50]) were also more likely immunized, and greater transportation access (OR=1.42, [1.07,1.87]) was associated with greater intention to vaccinate. Multi-level factors facilitated HBV vaccination in this population. Tailored, culturally appropriate communication strategies will positively influence immunization uptake. PMID:25506280

  15. Molecular epidemiology of norovirus in children and the elderly in Atlanta, Georgia, United States.

    PubMed

    Yi, Jumi; Wahl, Kelly; Sederdahl, Bethany K; Jerris, Robert R; Kraft, Colleen S; McCracken, Courtney; Gillespie, Scott; Anderson, Evan J; Kirby, Amy E; Shane, Andi L; Moe, Christine L

    2016-06-01

    Noroviruses are an important cause of gastroenteritis, which can be severe at the extremes of ages. Data documenting the endemic burden of norovirus among children and elderly adults are lacking. Stool specimens submitted for clinical testing were collected from elderly (≥ 65 years) adults and children (<18 years) with acute vomiting and/or diarrhea seeking care at several metropolitan Atlanta adult and pediatric hospitals from January 2013-June 2013. Specimens were tested for norovirus with real-time RT-PCR and sequenced if norovirus was detected. Corresponding clinical and demographic data were abstracted from retrospective chart review. Norovirus was detected in 11% (11/104) of elderly specimens and 11% (67/628) of pediatric, with GII.4 Sydney_2012 detected in 64% (7/11) of elderly norovirus-positive and 11% (8/67) of pediatric specimens, P < 0.001. In comparison to hospitalized children, hospitalized elderly with norovirus were more commonly admitted to the intensive care unit (ICU) (36% vs. 7%, P = 0.02). Norovirus in the elderly can be associated with severe illness requiring ICU admissions. The pediatric group demonstrated greater variability in genotype distribution. Ongoing surveillance of norovirus genotypes is crucial for norovirus vaccine development in understanding circulating and emerging genotypes.

  16. Future desire for children among women living with HIV in Atlanta, Georgia.

    PubMed

    Haddad, Lisa B; Machen, Leah Kathleen; Cordes, Sarah; Huylebroeck, Brian; Delaney, Augustina; Ofotokun, Igho; Nguyen, Minh Ly; Jamieson, Denise J

    2016-01-01

    Little is known regarding family planning desires among women living with HIV in the United States. This study aimed to identify factors influencing desire for children in the future among HIV-infected women in Atlanta, Georgia. HIV-infected women ages 18-45 completed an ACASI (audio computer-assisted self-interview) questionnaire. Chi-square, t-tests, and multivariate logistic regression evaluated factors associated with desire for future children. Of 181 participants, 62 (34.3%) expressed desire for children in the future, with increased desire among younger women (age <26) and those with seronegative partners. Concerns for horizontal and vertical HIV transmission were deterrents to future childbearing. Condom use and overall knowledge of transmission risk was low. Over a third of women desiring a child never discussed their desire with a physician. Misinformation regarding HIV transmission risks persists and is a notable concern influencing desire for children. Providers should reassess family planning desires regularly through integrated HIV care.

  17. Multilevel factors influencing hepatitis B screening and vaccination among Vietnamese Americans in Atlanta, Georgia.

    PubMed

    Frew, Paula M; Alhanti, Brooke; Vo-Green, Linda; Zhang, Siyu; Liu, Chang; Nguyen, Tranh; Schamel, Jay; Saint-Victor, Diane S; Nguyen, Minh Ly

    2014-12-01

    Chronic hepatitis B virus (HBV) infection may lead to liver cirrhosis, chronic liver disease, and liver cancer. Immunization rates are suboptimal among Asian Americans/Pacific Islanders (AAPIs), who remain disproportionately affected by these illnesses. We investigated socioecological factors affecting HBV prevention among 316 Vietnamese Americans in Atlanta, Georgia. Social and community support of HBV vaccination was associated with screening (OR=1.69, 95% CI [1.21,2.38]), vaccination (OR=1.89, [1.27,2.81]), and intent to vaccinate (OR=1.77, [1.13,2.78]). Misconceptions decreased screening likelihood (OR=0.67, [0.46,0.99]) and vaccination (OR=0.55, [0.35,0.86]). Those able to pay for medical treatment (OR=1.23, [1.01,1.50]) were also more likely immunized, and greater transportation access (OR=1.42, [1.07,1.87]) was associated with greater intention to vaccinate. Multi-level factors facilitated HBV vaccination in this population. Tailored, culturally appropriate communication strategies will positively influence immunization uptake.

  18. Susceptibility to Heat-Related Fluid and Electrolyte Imbalance Emergency Department Visits in Atlanta, Georgia, USA

    PubMed Central

    Heidari, Leila; Winquist, Andrea; Klein, Mitchel; O’Lenick, Cassandra; Grundstein, Andrew; Ebelt Sarnat, Stefanie

    2016-01-01

    Identification of populations susceptible to heat effects is critical for targeted prevention and more accurate risk assessment. Fluid and electrolyte imbalance (FEI) may provide an objective indicator of heat morbidity. Data on daily ambient temperature and FEI emergency department (ED) visits were collected in Atlanta, Georgia, USA during 1993–2012. Associations of warm-season same-day temperatures and FEI ED visits were estimated using Poisson generalized linear models. Analyses explored associations between FEI ED visits and various temperature metrics (maximum, minimum, average, and diurnal change in ambient temperature, apparent temperature, and heat index) modeled using linear, quadratic, and cubic terms to allow for non-linear associations. Effect modification by potential determinants of heat susceptibility (sex; race; comorbid congestive heart failure, kidney disease, and diabetes; and neighborhood poverty and education levels) was assessed via stratification. Higher warm-season ambient temperature was significantly associated with FEI ED visits, regardless of temperature metric used. Stratified analyses suggested heat-related risks for all populations, but particularly for males. This work highlights the utility of FEI as an indicator of heat morbidity, the health threat posed by warm-season temperatures, and the importance of considering susceptible populations in heat-health research. PMID:27706089

  19. Convention Proceedings Digest: American Vocational Association (Atlanta, Georgia, November 30-December 5, 1973).

    ERIC Educational Resources Information Center

    American Vocational Association, Inc., Washington, DC.

    The document is the fifth volume in an annual series of American Vocational Association (AVA) proceedings digests. It contains the reports of professional meetings, workshops, educational tours, speeches, and discussions, as well as the resolutions, elections, and other activities undertaken at the various meetings. The proceedings of meetings of…

  20. Magnitudes, nature, and effects of point and nonpoint discharges in the Chattahoochee River Basin, Atlanta to West Point Dam, Georgia

    USGS Publications Warehouse

    Stamer, J.K.; Cherry, Rodney N.; Faye, R.E.; Kleckner, R.L.

    1979-01-01

    During the period April 1975 to June 1978, the U.S. Geological Survey conducted a river-quality assessment of the Upper Chattahoochee River basin in Georgia. One objective of the study was to assess the magnitudes, nature, and effects of point and non-point discharges in the Chattahoochee River basin from Atlanta to the West Point Dam. On an average annual basis and during the storm period of March 1215, 1976, non-point-source loads for most constituents analyzed were larger than point-source loads at the Whitesburg station, located on the Chattahoochee River about 40 river miles downstream of Atlanta. Most of the non-point-source constituent loads in the Atlanta-to-Whitesburg reach were from urban areas. Average annual point-source discharges accounted for about 50 percent of the dissolved nitrogen, total nitrogen, and total phosphorus loads, and about 70 percent of the dissolved phosphorus loads at Whitesburg. During weekends, power generation at the upstream Buford Dam hydroelectric facility is minimal. Streamflow at the Atlanta station during dry-weather weekends is estimated to be about 1,200 ft3/s (cubic feet per second). Average daily dissolved-oxygen concentrations of less than 5.0 mg/L (milligrams per liter) occurred often in the river, about 20 river miles downstream from Atlanta during these periods from May to November. During a low-flow period, June 1-2, 1977, five municipal point sources contributed 63 percent of the ultimate biochemical oxygen demand, 97 percent of the ammonium nitrogen, 78 percent of the total nitrogen, and 90 percent of the total phosphorus loads at the Franklin station, at the upstream end of West Point Lake. Average daily concentrations of 13 mg/L of ultimate biochemical oxygen demand and 1.8 mg/L of ammonium nitrogen were observed about 2 river miles downstream from two of the municipal point sources. Carbonaceous and nitrogenous oxygen demands caused dissolved-oxygen concentrations between 4.1 and 5.0 mg/L to occur in a 22-mile

  1. Quantitative electron microscopy of InN-GaN alloys

    NASA Astrophysics Data System (ADS)

    Bartel, T.; Jinschek, J. R.; Freitag, B.; Specht, P.; Kisielowski, C.

    2006-01-01

    The local element distribution in quantum wells largely affects physical properties of devices made from such materials. In the past, quantitative electron microscopy was developed to access the stoichiometry on an atomic scale as shown on the cover page of this issue's Editor's Choice [1] for the GaN/InxGa1-xN/GaN and the GaAs/AlxGa1-xAs/GaAs system by the application of QUANTITEM and Chemical Imaging, respectively. In case of GaN/InxGa1-xN/GaN local strain mapping allows for extracting similar data and an unusual large indium fluctuation can be observed if compared with the aluminum distribution in GaAs/AlxGa1-xAs/GaAs quantum well structures. However, radiation damage, sample preparation and microscope stability affect the data analyses and it is of essence to monitor and control such effects as outlined in the related paper.The first author Til Bartel is a PhD candidate in physics at the Technical University of Berlin, currently visiting LBNL in California to apply transmission electron microscopy to III-nitride semiconductors. Christian Kisielowski is Staff Scientist and Principle Investigator at the National Center for Electron Microscopy (NCEM) and is responsible for the development and application of high resolution electron microscopy.The present special issue of physica status solidi (a) is a compilation of presentations from the recent symposium on Indium Nitride and Indium Rich Related Alloys at the E-MRS 2005 Fall Meeting in Warsaw.

  2. High-capacity, high-strength trailer designs for the GA-4/GA-9 Casks

    SciTech Connect

    Kissinger, J.A.; Rickard, N.D.; Taylor, C.; Zimmer, A.

    1991-01-01

    General Atomics (GA) is developing final designs for two dedicated legal-weight trailers to transport the GA-4 and GA-9 Spent-Fuel Casks. The basic designs for these high-capacity, high-strength trailers are essentially identical except for small modifications to account for the differences in cask geometry. We are designing both trailers to carry a 55,000 lb (24,900 kg) payload and to withstand a 2.5 g vertical design load. The GA-4 and GA-9 trailers are designed for significantly higher loads than are typical commercial semitrailers, which are designed to loads in the range of 1.7 to 2.0 g. To meet the federal gross vehicle weight limit for legal-weight trucks, GA has set a target design weight for the trailers of 9000 lb (4080 kg). This weight includes the personnel barrier, cask tiedowns, and impact limiter removal and storage system. Based on the preliminary trailer designs, the final design weight is expected to be very close to this target weight. 3 refs., 3 figs.

  3. Daily mortality and air pollution in Atlanta: two years of data from ARIES.

    PubMed

    Klemm, R J; Lipfert, F W; Wyzga, R E; Gust, C

    2004-01-01

    Associations between daily mortality and air pollution were investigated in Fulton and DeKalb Counties, Georgia, for the 2-yr period beginning in August 1998, as part of the Aerosol Research and Inhalation Epidemiological Study (ARIES). Mortality data were obtained directly from county offices of vital records. Air quality data were obtained from a dedicated research site in central Atlanta; 15 separate air quality indicators (AQIs) were selected from the 70 particulate and gaseous air quality parameters archived in the ARIES ambient air quality database. Daily meteorological parameters, comprising 24-h average temperatures and dewpoints, were obtained from Atlanta's Hartsfield International Airport. Effects were estimated using Poisson regression with daily deaths as the response variable and time, meteorology, AQI, and days of the week as predictor variables. AQI variables entered the model in a linear fashion, while all other continuous predictor variables were smoothed via natural cubic splines using the generalized linear model (GLM) framework in S-PLUS. Knots were spaced either quarterly, monthly, or biweekly for temporal smoothing. A default model using monthly knots and AQIs averaged for lags 0 and 1 was postulated, with other models considered in sensitivity analyses. Lags up to 5 days were considered, and multipollutant models were evaluated, taking care to avoid overlapping (and thus collinear) AQIs. For this reason, PM(2.5) was partitioned into its three major constituents: SO(2-)(4), carbon (EC + 1.4 OC), and the remainder; sulfate was assumed to be (NH(4))(2)SO(4) for this purpose. Initial AQI screening was based on all-cause (ICD-9 codes <800) mortality for those aged 65 and over. For the (apparently) most important pollutants--PM(2.5) and its 3 major constituents, coarse PM mass [CM], 1-h maximum CO, 8-h maximum O(3)--we investigated 15 mortality categories in detail. (The 15 categories result from three age groups [all ages, <65, 65+] and five

  4. DRINKING WATER TURBIDITY AND EMERGENCY DEPARTMENT VISITS FOR GASTROINTESTINAL ILLNESS IN ATLANTA, 1993 – 2004

    PubMed Central

    Tinker, Sarah C.; Moe, Christine L.; Klein, Mitchel; Flanders, W. Dana; Uber, Jim; Amirtharajah, Appiah; Singer, Philip; Tolbert, Paige E.

    2013-01-01

    Background The extent to which drinking water turbidity measurements indicate the risk of gastrointestinal illness is not well-understood. Despite major advances in drinking water treatment and delivery, infectious disease can still be transmitted through drinking water in the U.S., and it is important to have reliable indicators of microbial water quality to inform public health decisions. The objective of our study was to assess the relationship between gastrointestinal illness, quantified through emergency department visits, and drinking water quality, quantified as raw water and filtered water turbidity measured at the treatment plant. Methods We examined the relationship between turbidity levels of raw and filtered surface water measured at eight major drinking water treatment plants in the metropolitan area of Atlanta, Georgia, and over 240 000 emergency department visits for gastrointestinal illness during 1993–2004 among the population served by these plants. We fit Poisson time-series statistical regression models that included turbidity in a 21-day distributed lag and that controlled for meteorological factors and long-term time trends. Results For filtered water turbidity, the results were consistent with no association with emergency department visits for gastrointestinal illness. We observed a modest association between raw water turbidity and emergency department visits for gastrointestinal illness. This association was not observed for all treatment plants in plant-specific analyses. Conclusions Our results suggest that source water quality may contribute modestly to endemic gastrointestinal illness in the study area. The association between turbidity and emergency department visits for gastrointestinal illness was only observed when raw water turbidity was considered; filtered water turbidity may not serve as a reliable indicator of modest pathogen risk at all treatment plants. PMID:18941478

  5. Drinking water turbidity and emergency department visits for gastrointestinal illness in Atlanta, 1993-2004.

    PubMed

    Tinker, Sarah C; Moe, Christine L; Klein, Mitchel; Flanders, W Dana; Uber, Jim; Amirtharajah, Appiah; Singer, Philip; Tolbert, Paige E

    2010-01-01

    The extent to which drinking water turbidity measurements indicate the risk of gastrointestinal illness is not well understood. Despite major advances in drinking water treatment and delivery, infectious disease can still be transmitted through drinking water in the United States, and it is important to have reliable indicators of microbial water quality to inform public health decisions. The objective of our study was to assess the relationship between gastrointestinal illness, quantified through emergency department visits, and drinking water quality, quantified as raw water and filtered water turbidity measured at the treatment plant. We examined the relationship between turbidity levels of raw and filtered surface water measured at eight major drinking water treatment plants in the metropolitan area of Atlanta, Georgia, and over 240,000 emergency department visits for gastrointestinal illness during 1993-2004 among the population served by these plants. We fit Poisson time-series statistical regression models that included turbidity in a 21-day distributed lag and that controlled for meteorological factors and long-term time trends. For filtered water turbidity, the results were consistent with no association with emergency department visits for gastrointestinal illness. We observed a modest association between raw water turbidity and emergency department visits for gastrointestinal illness. Our results suggest that source water quality may contribute modestly to endemic gastrointestinal illness in the study area. The association between turbidity and emergency department visits for gastrointestinal illness was only observed when raw water turbidity was considered; filtered water turbidity may not serve as a reliable indicator of modest pathogen risk at all treatment plants.

  6. Effects of urbanization on stream water quality in the city of Atlanta, Georgia, USA

    USGS Publications Warehouse

    Peters, N.E.

    2009-01-01

    A long-term stream water quality monitoring network was established in the city of Atlanta, Georgia during 2003 to assess baseline water quality conditions and the effects of urbanization on stream water quality. Routine hydrologically based manual stream sampling, including several concurrent manual point and equal width increment sampling, was conducted ???12 times annually at 21 stations, with drainage areas ranging from 3.7 to 232 km2. Eleven of the stations are real-time (RT) stations having continuous measures of stream stage/ discharge, pH, dissolved oxygen, specific conductance, water temperature and turbidity, and automatic samplers for stormwater collection. Samples were analyzed for field parameters, and a broad suite of water quality and sediment-related constituents. Field parameters and concentrations of major ions, metals, nutrient species and coliform bacteria among stations were evaluated and with respect to watershed characteristics and plausible sources from 2003 through September 2007. Most constituent concentrations are much higher than nearby reference streams. Concentrations are statistically different among stations for several constituents, despite high variability both within and among stations. Routine manual sampling, automatic sampling during stormflows and RT water quality monitoring provided sufficient information about urban stream water quality variability to evaluate causes of water quality differences among streams. Fecal coliform bacteria concentrations of most samples exceeded Georgia's water quality standard for any water-usage class. High chloride concentrations occur at three stations and are hypothesized to be associated with discharges of chlorinated combined sewer overflows, drainage of swimming pool(s) and dissolution and transport during rainstorms of CaCl2, a deicing salt applied to roads during winter storms. One stream was affected by dissolution and transport of ammonium alum [NH4Al(SO4)2] from an alum

  7. Trisomies 13 and 18: population prevalences, characteristics, and prenatal diagnosis, metropolitan Atlanta, 1994-2003.

    PubMed

    Crider, Krista S; Olney, Richard S; Cragan, Janet D

    2008-04-01

    In recent years, prenatal diagnosis and elective pregnancy termination have affected the reported birth prevalence of trisomies 13 and 18. We examined the prevalence and characteristics of these conditions using 1994-2003 data from a population-based surveillance system, the Metropolitan Atlanta Congenital Defects Program. Including fetal deaths and elective terminations increased the number of affected pregnancies by 58.7% for trisomy 13 and 72.2% for trisomy 18. Prenatal cytogenetic testing was reported in 70.8% of trisomy 13 cases and 76.1% of trisomy 18 cases. Among those with prenatal cytogenetic tests, 60.8% of trisomy 13 and 59.7% of trisomy 18 cases were electively terminated. Compared with non-Hispanic whites, non-Hispanic black race was associated with a decreased frequency of prenatal cytogenetic testing for both trisomy 13 and trisomy 18 (OR 0.24, 95% CI: 0.08-0.78 and OR 0.32, 95% CI: 0.14-0.69, respectively). The reported rates of prenatal cytogenetic testing remained stable throughout the period. As expected, maternal age > or =35 years was a risk factor for both conditions. However, while 67.1% (n = 55) of the trisomy 18 case mothers were > or =35 years, only 46.9% (n = 15) of the trisomy 13 case mothers were > or =35 years. Among live-born infants, the sex ratio among trisomy 18 infants showed an increased proportion of females: 60.4% female versus 39.6% male. However, the proportion was 48.3% female and 51.7% male among fetuses that were electively terminated in the second trimester. Inclusion of pregnancies that are prenatally diagnosed is critical for accurate surveillance and population-based analyses of these conditions. PMID:18348276

  8. Reduction of Methicillin-Resistant Staphylococcus aureus Infection among Veterans in Atlanta

    PubMed Central

    Stenehjem, Edward; Stafford, Cortney; Rimland, David

    2013-01-01

    OBJECTIVE Describe local changes in the incidence of community-onset and hospital-onset methicillin-resistant Staphylococcus aureus (MRSA) infection and evaluate the impact of MRSA active surveillance on hospital-onset infection. DESIGN Observational study using prospectively collected data. SETTING Atlanta Veterans Affairs Medical Center (AVAMC). PATIENTS All patients seen at the AVAMC over an 8-year period with clinically and microbiologically proven MRSA infection. METHODS All clinical cultures positive for MRSA were prospectively identified, and corresponding clinical data were reviewed. MRSA infections were classified into standard clinical and epidemiologic categories. The Veterans Health Administration implemented the MRSA directive in October 2007, which required active surveillance cultures in acute care settings. RESULTS The incidence of community-onset MRSA infection peaked in 2007 at 5.45 MRSA infections per 1,000 veterans and decreased to 3.14 infections per 1,000 veterans in 2011 (P ≤ .001 for trend). Clinical and epidemiologic categories of MRSA infections did not change throughout the study period. The prevalence of nasal MRSA colonization among veterans admitted to AVAMC decreased from 15.8% in 2007 to 11.2% in 2011 (P < .001 for trend). The rate of intensive care unit (ICU)–related hospital-onset MRSA infection decreased from October 2005 through March 2007, before the MRSA directive. Rates of ICU-related hospital-onset MRSA infection remained stable after the implementation of active surveillance cultures. No change was observed in rates of non-ICU-related hospital-onset MRSA infection. CONCLUSIONS Our study of the AVAMC population over an 8-year period shows a consistent trend of reduction in the incidence of MRSA infection in both the community and healthcare settings. The etiology of this reduction is most likely multifactorial. PMID:23221194

  9. Racial disparities in travel time to radiotherapy facilities in the Atlanta metropolitan area.

    PubMed

    Peipins, Lucy A; Graham, Shannon; Young, Randall; Lewis, Brian; Flanagan, Barry

    2013-07-01

    Low-income women with breast cancer who rely on public transportation may have difficulty in completing recommended radiation therapy due to inadequate access to radiation facilities. Using a geographic information system (GIS) and network analysis we quantified spatial accessibility to radiation treatment facilities in the Atlanta, Georgia metropolitan area. We built a transportation network model that included all bus and rail routes and stops, system transfers and walk and wait times experienced by public transportation system travelers. We also built a private transportation network to model travel times by automobile. We calculated travel times to radiation therapy facilities via public and private transportation from a population-weighted center of each census tract located within the study area. We broadly grouped the tracts by low, medium and high household access to a private vehicle and by race. Facility service areas were created using the network model to map the extent of areal coverage at specified travel times (30, 45 and 60 min) for both public and private modes of transportation. The median public transportation travel time to the nearest radiotherapy facility was 56 min vs. approximately 8 min by private vehicle. We found that majority black census tracts had longer public transportation travel times than white tracts across all categories of vehicle access and that 39% of women in the study area had longer than 1 h of public transportation travel time to the nearest facility. In addition, service area analyses identified locations where the travel time barriers are the greatest. Spatial inaccessibility, especially for women who must use public transportation, is one of the barriers they face in receiving optimal treatment.

  10. From Olympia to Atlanta: a cultural-historical perspective on diet and athletic training.

    PubMed

    Grivetti, L E; Applegate, E A

    1997-05-01

    Greek and Roman writers described diet and training of Olympic athletes. Lucian (A.D. 120-ca. 180) described distance and speed work in runners; Galen (A.D. 131-201) recommended ball-related exercises to train vision and the body; Philostratos (A.D. 170-249) suggested cross training by endurance running, weight training, and wrestling with animals. The ancient Greek training system, the tetrad (eta tau epsilon tau rho alpha sigma), was a four-day cycle with each day devoted to a different activity. Diogenes Laertius (died A.D. 222) wrote that Greek athletes trained on dried figs, moist cheese and wheat; then the pattern changed and focused on meat. Epictetus (2nd century A.D.) wrote that Olympic victors avoided desserts and cold water and took wine sparingly. Philostratos deprecated athletic diet in his era, a pattern based on white bread sprinkled with poppy seeds, fish and pork. Americans at the XIth Olympiad in Berlin (1936) consumed beefsteak with average daily intake of 125 grams of butter or cotton oil, three eggs, custard for dessert and 1.5 L of milk. The American pattern at Berlin was characterized by ad libitum intake of white bread, dinner rolls, fresh vegetables and salads. At Atlanta, more than 5 million meals will be served during the Olympic festival. The highly varied menu will include fresh vegetables and dips; fruits, cheeses and breads; salads; pasta, rice and fruit salads; soups; meat and seafood entrees; hot vegetables; desserts; and beverages. American Southern specialties will be served.

  11. Application of the ASME code in the design of the GA-4 and GA-9 casks

    SciTech Connect

    Mings, W.J. ); Koploy, M.A. )

    1992-01-01

    General Atomics (GA) is developing two spent fuel shipping casks for transport by legal weight truck (LWT). The casks are designed to the loading, environmental conditions and safety requirements defined in Title 10 of the Code of Federal Regulations, Part 71 (10CFR71). To ensure that all components of the cask meet the 10CFR71 rules, GA established structural design criteria for each component based on NRC Regulatory Guides and the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code). This paper discusses the criteria used for different cask components, how they were applied and the conservatism and safety margins built into the criteria and assumption.

  12. Application of the ASME code in the design of the GA-4 and GA-9 casks

    SciTech Connect

    Mings, W.J.; Koploy, M.A.

    1992-08-01

    General Atomics (GA) is developing two spent fuel shipping casks for transport by legal weight truck (LWT). The casks are designed to the loading, environmental conditions and safety requirements defined in Title 10 of the Code of Federal Regulations, Part 71 (10CFR71). To ensure that all components of the cask meet the 10CFR71 rules, GA established structural design criteria for each component based on NRC Regulatory Guides and the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code). This paper discusses the criteria used for different cask components, how they were applied and the conservatism and safety margins built into the criteria and assumption.

  13. Dietary patterns among the Metro Atlanta Cohort: implications for population-based longitudinal dietary pesticide exposure and risk assessment.

    PubMed

    Riederer, Anne M; Pearson, Melanie A; Lu, Chensheng

    2011-01-01

    Characterizing dietary consumption patterns is critical to dietary pesticide exposure assessment. We compared consumption patterns between adults (age 18-60) in the Metro Atlanta Cohort (MAC), a longitudinal study of pesticide exposure among Atlanta residents, and US National Health and Nutrition Examination Survey (NHANES) adults. We focused on foods commonly eaten by US adults and foods likely to contain certain pesticide residues. MAC participants provided consumption data for 6 days per month for 1 year using a web-based data collection tool. We defined "percent eaters" as the percent of participants who reported eating a particular food in 24 h. We computed the NHANES weighted percent eaters and 95% confidence limits (CLs) using the 24-h dietary recall data. We calculated the MAC percent eaters for each sampling day and the percent of days this number fell below, within, or above the NHANES 95% CLs. We also re-sampled the MAC percent eaters across sampling days to find whether the resulting distribution resembled the NHANES estimate, and used the Kruskal-Wallis test to evaluate whether season affected the number of MAC eaters of a particular food on a given sampling day. In general, across all sampling days, a greater proportion of MAC participants reported eating banana, broccoli, cream, grapes, lettuce, onion, peach, pear, peas, strawberries, string beans, and tomatoes than the national estimate, whereas the proportion of apple, spinach, ketchup and white bread/roll eaters was similar, and the proportion of milk drinkers was lower. Season predicted the number of MAC peach and strawberry eaters but not other foods. The data show how a higher proportion of Atlanta adults may eat certain foods (e.g., peaches in summer or strawberries in spring) than the national average depending on season or other factors. An exposure assessment that ignored this difference could underestimate dietary pesticide intakes. PMID:20354565

  14. Housing values, census estimates, disequilibrium, and the environmental cost of airport noise: a case study of Atlanta

    SciTech Connect

    O'Byrne, P.H.; Nelson, J.P.; Seneca, J.J.

    1985-06-01

    Two unresolved issues about airport noise-property value studies are addressed. The first issue concerns the comparability of empirical results from aggregate census data vs individual sales values, and the second issue concerns the homogeneity and stability of results from housing price studies over time and across markets. Hedonic price models from two sets of data for a residential area near the Atlanta International Airport are estimated at two points in time, 1979-1980 and 1970-1972. The available data yield similar estimates of the noise discount over time, and from the prices of individual house sales vs owner-appraised census block aggregates. 26 references, 3 tables

  15. Modeling highly transient flow, mass, and heat transport in the Chattahoochee River near Atlanta, Georgia

    USGS Publications Warehouse

    Jobson, Harvey E.; Keefer, Thomas N.

    1979-01-01

    A coupled flow-temperature model has been developed and verified for a 27.9-km reach of the Chattahoochee River between Buford Dam and Norcross, Ga. Flow in this reach of the Chattahoochee is continuous but highly regulated by Buford Dam, a flood-control and hydroelectric facility located near Buford, Ga. Calibration and verification utilized two sets of data collected under highly unsteady discharge conditions. Existing solution techniques, with certain minor improvements, were applied to verify the existing technology of flow and transport modeling. A linear, implicit finite-difference flow model was coupled with implicit, finite-difference transport and temperature models. Both the conservative and nonconservative forms of the transport equation were solved, and the difference in the predicted concentrations of dye were found to be insignificant. The temperature model, therefore, was based on the simpler nonconservative form of the transport equation. (Woodard-USGS)

  16. The Atlanta Urban Heat Island Mitigation and Air Quality Modeling Project: How High-Resoution Remote Sensing Data Can Improve Air Quality Models

    NASA Technical Reports Server (NTRS)

    Quattrochi, Dale A.; Estes, Maurice G., Jr.; Crosson, William L.; Khan, Maudood N.

    2006-01-01

    The Atlanta Urban Heat Island and Air Quality Project had its genesis in Project ATLANTA (ATlanta Land use Analysis: Temperature and Air quality) that began in 1996. Project ATLANTA examined how high-spatial resolution thermal remote sensing data could be used to derive better measurements of the Urban Heat Island effect over Atlanta. We have explored how these thermal remote sensing, as well as other imaged datasets, can be used to better characterize the urban landscape for improved air quality modeling over the Atlanta area. For the air quality modeling project, the National Land Cover Dataset and the local scale Landpro99 dataset at 30m spatial resolutions have been used to derive land use/land cover characteristics for input into the MM5 mesoscale meteorological model that is one of the foundations for the Community Multiscale Air Quality (CMAQ) model to assess how these data can improve output from CMAQ. Additionally, land use changes to 2030 have been predicted using a Spatial Growth Model (SGM). SGM simulates growth around a region using population, employment and travel demand forecasts. Air quality modeling simulations were conducted using both current and future land cover. Meteorological modeling simulations indicate a 0.5 C increase in daily maximum air temperatures by 2030. Air quality modeling simulations show substantial differences in relative contributions of individual atmospheric pollutant constituents as a result of land cover change. Enhanced boundary layer mixing over the city tends to offset the increase in ozone concentration expected due to higher surface temperatures as a result of urbanization.

  17. Scaling animal to human biodistribution of the radiopharmaceutical [68Ga]Ga-PSMA-HBED-CC

    NASA Astrophysics Data System (ADS)

    Parra, Pamela Ochoa; Veloza, Stella

    2016-07-01

    The radiotracer called 68Ga-labelled Glu-urea-Lys(Ahx)-HBED-CC ([68Ga]Ga-PSMA-HBED-CC) is a novel radiophar-maceutical for the detection of prostate cancer lesions by positron emission tomography (PET) imaging. Setting up a cost-effective manual synthesis of this radiotracer and making its clinical translation in Colombia will require two important elements: the evaluation of the procedure to yield a consistent product, meeting standards of radio-chemical purity and low toxicity and then, the evaluation of the radiation dosimetry. In this paper a protocol to extrapolate the biokinetic model made in normal mice to humans by using the computer software for internal dose assessment OLINDA/EXM® is presented as an accurate and standardized method for the calculation of radiation dosimetry estimates.

  18. The 1996 meeting of the national technical workgroup on mixed waste thermal treatment

    SciTech Connect

    1996-12-31

    The National Technical Workgroup on Mixed Waste Thermal Treatment held its annual meeting in Atlanta Georgia on March 12-14, 1996. The National Technical Workgroup (NTW) and this meeting were sponsored under an interagency agreement between EPA and DOE. The 1996 Annual Meeting was hosted by US DOE Oak Ridge Operations in conjunction with Lockheed Martin Energy Systems - Center for Waste Management. A new feature of the annual meeting was the Permit Writer Panel Session which provided an opportunity for the state and federal permit writers to discuss issues and potential solutions to permitting mixed waste treatment systems. In addition, there was substantial discussion on the impacts of the Waste Combustion Performance Standards on mixed waste thermal treatment which are expected to proposed very soon. The 1996 meeting also focussed on two draft technical resource documents produced by NTW on Waste Analysis Plans and Compliance Test Procedures. Issues discussed included public involvement, waste characterization, and emission issues.

  19. Fuel-based fine particulate and black carbon emission factors from a railyard area in Atlanta.

    PubMed

    Galvis, Boris; Bergin, Mike; Russell, Armistead

    2013-06-01

    Railyards have the potential to influence localfine particulate matter (aerodynamic diameter < or = 2.5 microm; PM2.5) concentrations through emissions from diesel locomotives and supporting activities. This is of concern in urban regions where railyards are in proximity to residential areas. Northwest of Atlanta, Georgia, Inman and Tilford railyards are located beside residential neighborhoods, industries, and schools. The PM2.5 concentrations near the railyards is the highest measured amongst the state-run monitoring sites (Georgia Environmental Protection Division, 2012; http://www.georgiaair.org/amp/report.php). The authors estimated fuel-based black carbon (BC) and PM2.5 emission factors for these railyards in order to help determine the impact of railyard activities on PM2.5 concentrations, and for assessing the potential benefits of replacing current locomotive engines with cleaner technologies. High-time-resolution measurements of BC, PM2.5, CO2, and wind speed and direction were made at two locations, north and south of the railyards. Emissions factors (i.e., the mass of BC or PM2.5 per gallon of fuel burned) were estimated by using the downwind/upwind difference in concentrations, wavelet analysis, and an event-based approach. By the authors' estimates, diesel-electric engines used in the railyards have average emission factors of 2.8 +/- 0.2 g of BC and 6.0 +/- 0.5 g of PM2.5 per gallon of diesel fuel burned. A broader mix of railyard supporting activities appear to lead to average emission factors of 0.7 +/- 0.03 g of BC and 1.5 +/- 0.1 g of PM2.5 per gallon of diesel fuel burned. Railyard emissions appear to lead to average enhancements of approximately 1.7 +/- 0.1 microg/m3 of PM2.5 and approximately 0.8 +/- 0.01 microg/m3 of BC in neighboring areas on an annual average basis. Uncertainty not quantified in these results could arise mainly from variability in downwind/upwind differences, differences in emissions of the diverse zones within the

  20. Evaluation of stream water quality in Atlanta, Georgia, and the surrounding region (USA)

    USGS Publications Warehouse

    Peters, N.E.; Kandell, S.J.

    1999-01-01

    A water-quality index (WQI) was developed from historical data (1986-1995) for streams in the Atlanta Region and augmented with 'new' and generally more comprehensive biweekly data on four small urban streams, representing an industrial area, a developed medium-density residential area and developing and developed low-density residential areas. Parameter WQIs were derived from percentile ranks of individual water-quality parameter values for each site by normalizing the constituent ranks for values from all sites in the area for a base period, i.e. 1990-1995. WQIs were developed primarily for nutrient-related parameters due to data availability. Site WQIs, which were computed by averaging the parameter WQIs, range from 0.2 (good quality) to 0.8 (poor quality), and increased downstream of known nutrient sources. Also, annual site WQI decreases from 1986 to 1995 at most long-term monitoring sites. Annual site WQI for individual parameters correlated with annual hydrological characteristics, particularly runoff, precipitation quantity, and water yield, reflecting the effect of dilution on parameter values. The WQIs of the four small urban streams were evaluated for the core-nutrient-related parameters, parameters for specific dissolved trace metal concentrations and sediment characteristics, and a species diversity index for the macro-invertebrate taxa. The site WQI for the core-nutrient-related parameters used in the retrospective analysis was, as expected, the worst for the industrial area and the best for the low-density residential areas. However, macro-invertebrate data indicate that although the species at the medium-density residential site were diverse, the taxa at the site were for species tolerant of degraded water quality. Furthermore, although a species-diversity index indicates no substantial difference between the two low-density residential areas, the number for macro-invertebrates for the developing area was much less than that for the developed area

  1. Effects of Urbanization on Stream Water Quality in the City of Atlanta, Georgia, USA

    NASA Astrophysics Data System (ADS)

    Peters, N. E.

    2009-05-01

    A long-term stream water-quality monitoring network was established in the City of Atlanta (COA) during 2003 to assess baseline water-quality conditions and the effects of urbanization on stream water quality. Routine hydrologically-based manual stream sampling, including several concurrent manual point and equal width increment sampling, was conducted approximately 12 times per year at 21 stations, with drainage areas ranging from 3.7 to 232 km2. Eleven of the stations are real-time (RT) water-quality stations having continuous measures of stream stage/discharge, pH, dissolved oxygen, specific conductance, water temperature, and turbidity, and automatic samplers for stormwater collection. Samples were analyzed for field parameters, and a broad suite of water-quality and sediment-related constituents. This paper summarizes an evaluation of field parameters and concentrations of major ions, minor and trace metals, nutrient species (nitrogen and phosphorus), and coliform bacteria among stations and with respect to watershed characteristics and plausible sources from 2003 through September 2007. The concentrations of most constituents in the COA streams are statistically higher than those of two nearby reference streams. Concentrations are statistically different among stations for several constituents, despite high variability both within and among stations. The combination of routine manual sampling, automatic sampling during stormflows, and real-time water-quality monitoring provided sufficient information about the variability of urban stream water quality to develop hypotheses for causes of water-quality differences among COA streams. Fecal coliform bacteria concentrations of most individual samples at each station exceeded Georgia's water-quality standard for any water-usage class. High chloride concentrations occur at three stations and are hypothesized to be associated with discharges of chlorinated combined sewer overflows, drainage of swimming pool(s), and

  2. Managing Meetings

    ERIC Educational Resources Information Center

    Hay, Susan

    2010-01-01

    Meetings are a means of giving people a chance to contribute. Meetings are also the nursery where the people's skills of listening, speaking, and building good working relationships are honed. They are where people practice being courteously challenging and confident, and they are where people are fascinated and fascinating. Meetings are where…

  3. Use of an inverse method to resolve the temporal and spatial distribution of anthropogenic and biogenic emissions in Atlanta, Georgia

    SciTech Connect

    Chang, M.E.; Hartley, D.; Cardelino, C.; Chang, W.L.

    1996-12-31

    The Urban Airshed Model (UAM) has been used by the State of Georgia in an attempt to demonstrate attainment of the ozone standard for Atlanta. A recent comparison of UAM data to ambient data collected during the 1992 Southern Oxidants Study Atlanta intensive revealed that the model accurately predicts ozone concentrations, but is poorly simulates the concurrent ozone precursors. There were discrepancies in both the anthropogenic and biogenic precursors. For anthropogenic emissions, the ambient ratios of anthropogenic hydrocarbons (AHC) to oxides of nitrogen (NO{sub x}), AHC/NO{sub x}, and carbon monoxide (CO) to NO{sub x}, CO/NO{sub x}, were higher than the emission ratios by 20% and 73% respectively. In this study, the authors use an inverse method to reconcile the differences between the observed and predicted concentrations of ozone precursors. Inverse methods have been successfully applied to many fields including medical imaging, missile guidance, and underground tomography. This study is the first to apply the inverse method to estimate the emissions of the relatively short-lived species important to urban oxidants formation.

  4. Improved InGaN/GaN light-emitting diodes with a p-GaN/n-GaN/p-GaN/n-GaN/p-GaN current-spreading layer.

    PubMed

    Zhang, Zi-Hui; Tan, Swee Tiam; Liu, Wei; Ju, Zhengang; Zheng, Ke; Kyaw, Zabu; Ji, Yun; Hasanov, Namig; Sun, Xiao Wei; Demir, Hilmi Volkan

    2013-02-25

    This work reports both experimental and theoretical studies on the InGaN/GaN light-emitting diodes (LEDs) with optical output power and external quantum efficiency (EQE) levels substantially enhanced by incorporating p-GaN/n-GaN/p-GaN/n-GaN/p-GaN (PNPNP-GaN) current spreading layers in p-GaN. Each thin n-GaN layer sandwiched in the PNPNP-GaN structure is completely depleted due to the built-in electric field in the PNPNP-GaN junctions, and the ionized donors in these n-GaN layers serve as the hole spreaders. As a result, the electrical performance of the proposed device is improved and the optical output power and EQE are enhanced.

  5. Durability testing of the high-capacity GA-4/GA-9 trailer

    SciTech Connect

    Zimmer, A.

    1993-08-01

    General Atomics (GA) is under contract to the US Department of Energy (DOE), Idaho Field Office, to develop two legal-weight truck from-reactor spent-fuel shipping casks with trailers. GA is developing these high capacity transport systems to support the Office of Civilian Radioactive Waste Management`s (OCRWM) mission to transport spent fuel from reactors to a permanent disposal site. GA`s goal is to maximize the number of fuel assemblies that the transport system can safely carry. The GA-4 Cask is being designed to transport four pressurized-water-reactor (PWR) spent-fuel assemblies, and the GA-9 Cask is being designed to transport nine boiling-water-reactor (BWR) spent-fuel assemblies. The use of these high-capacity transport systems will have a large benefit to-public safety since the number of legal-weight truck shipments will be reduced by at least a factor of four over existing spent-fuel shipping cask systems. Achieving these capacities requires that the weight of each component of the transport system. i.e., cask, trailer and tractor, be minimized. The weight of the trailer is of particular importance. With a high load-to-weight ratio, the durability and reliability of the trailer become significant factors in the success of the transport system. In order to verify that the trailer design will meet the durability and performance requirements to safely transport spent-fuel, GA has planned an extensive testing program. The testing program includes non-destructive examination (NDE) of the trailer welds, operational testing, a static load test, an over-the-road performance test, and a test to verify the durability of the trailer up to its 1,000,000-mile design life. Since a prototype cask will not be available for the testing, GA designed and built a dummy payload that simulates the correct weight distribution and approximates the dynamic response of the prototype cask.

  6. Microwave GaAs Integrated Circuits On Quartz Substrates

    NASA Technical Reports Server (NTRS)

    Siegel, Peter H.; Mehdi, Imran; Wilson, Barbara

    1994-01-01

    Integrated circuits for use in detecting electromagnetic radiation at millimeter and submillimeter wavelengths constructed by bonding GaAs-based integrated circuits onto quartz-substrate-based stripline circuits. Approach offers combined advantages of high-speed semiconductor active devices made only on epitaxially deposited GaAs substrates with low-dielectric-loss, mechanically rugged quartz substrates. Other potential applications include integration of antenna elements with active devices, using carrier substrates other than quartz to meet particular requirements using lifted-off GaAs layer in membrane configuration with quartz substrate supporting edges only, and using lift-off technique to fabricate ultrathin discrete devices diced separately and inserted into predefined larger circuits. In different device concept, quartz substrate utilized as transparent support for GaAs devices excited from back side by optical radiation.

  7. 11 CFR 2.4 - Exempted meetings.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Commission directives setting forth job functions or procedures; (2) Financial or commercial information... observation in accordance with the procedures of 11 CFR 2.5. (1) As required by 2 U.S.C. 437g(a)(12), all... forth in 11 CFR part 111. (b) Meetings closed by Commission determination. Except as provided in 11...

  8. Health Impact Assessment of the Boone Boulevard Green Street Project in the Proctor Creek Watershed of Atlanta - Urban Waters National Training Workshop

    EPA Science Inventory

    Proctor Creek is one of the most impaired creeks in metro-Atlanta due to exceedance of state water quality standards for fecal coliforms. The topography, prevalence of impervious surfaces in the watershed, and a strained combined sewer system have contributed to pervasive floodin...

  9. Haemophilus influenzae Type b Carriage among Young Children in Metropolitan Atlanta in the Context of Vaccine Shortage and Booster Dose Deferral ▿

    PubMed Central

    Thomas, Jennifer Dolan; Jackson, Michael L.; Sharma, Dolly; Mair, Raydel; Bach, Michelle C.; Castillo, Dana; Ejigiri, O. Grace; Satola, Sarah; Cohn, Amanda C.; Jerris, Robert; Jain, Shabnam; Farley, Monica M.; Mayer, Leonard W.; Messonnier, Nancy E.

    2011-01-01

    Short-term deferral of the Haemophilus influenzae type b (Hib) vaccine booster dose during a recent U.S. Hib vaccine shortage did not result in widespread Hib carriage in Atlanta, as the Hib carriage rate was found to be 0.3% (1/342). Hib colonization was significantly more common among males and day care attendees. PMID:22012977

  10. The Olympic Spirit: History of the Games and Atlanta Committee for the Olympic Games, Volume I, 1992-93 Curriculum Guide. Olympic Day in the Schools.

    ERIC Educational Resources Information Center

    Atlanta Committee for the Olympic Games, GA.

    This curriculum guide is designed to promote excellence in the lives of students while empowering them to learn, appreciate, and practice the values inherent in the Olympic Movement and to recognize the learning opportunity of the 1996 Atlanta Centennial Olympic Games. The program seeks to integrate academic content from across the disciplines…

  11. The Effect of the Thor Ruling on School Librarian's Ability to Obtain Copies of Children's Literature and Reference Materials in Atlanta Public Schools.

    ERIC Educational Resources Information Center

    Van Liew, Gayle Dorothy

    Data collected from library acquisition records on microfiche helped ascertain the effects of the Thor Power Tool Company Supreme Court decision in 1979 on a sampling of four randomly selected schools in the Atlanta Public School System between 1978 and 1985. Prior to this decision, some publishers kept a substantial inventory of backlist titles…

  12. A Reply to Diem et al.'s Commentary on a Recent Literature Contribution Focused on Urban-Induced Rainfall in Atlanta

    NASA Technical Reports Server (NTRS)

    Shepherd, J. Marshall

    2004-01-01

    A response is provided to Diem and colleagues discussion on the whether urbanization-enhanced precipitation should be maximized in the South-Southeast of Atlanta, Georgia as documented in Shepherd et al. (2003). Diem and colleagues have offered a critical response to Shepherd et al. (2002). The response herein offers both general and specific responses to issues raised by Diem and colleagues.

  13. Opportunities for Improving Federally Assisted Manpower Programs Identified As a Result of Review in the Atlanta, Georgia, Area. Report to the Congress.

    ERIC Educational Resources Information Center

    Comptroller General of the U.S., Washington, DC.

    The combined impact of all federally assisted manpower programs in the Atlanta area was evaluated, with emphasis on outreach, eligibility, identification of needs and abilities, and screening for course assignment. In fiscal year 1970, training was provided for 10,300 persons and job placement for 5,600, although most of the estimated 70,000 poor…

  14. Atlanta's Successful Charles R. Drew Charter School: The Cornerstone of East Lake's Community Transformation. The Abell Report. Volume 27, No.1

    ERIC Educational Resources Information Center

    Eberhart, Linda; Barnes, Tara

    2014-01-01

    The community of East Lake, home to Charles R. Drew Charter School (Drew), is 6 miles from downtown Atlanta. In 1995, crime in East Lake was 19 times higher than the national average. Now, violent crime is down 95 percent. In 1995, 88 percent of residents were unemployed. Now, only 5 percent receive welfare. In 1995, just 5 percent of fifth…

  15. [Pupil Performance in the Elementary Schools of Atlanta.] Research and Development Report, Volume 5, Numbers 22-25, 27, 30, 44, and 45.

    ERIC Educational Resources Information Center

    Atlanta Public Schools, GA.

    These analyses are part of an effort to develop a method of showing accountability for the educational responsibilities of the school system to the children of Atlanta, Georgia. The evaluations focus on the rationale of ongoing programs, pupil needs, program goals, behavioral objectives, management and control, cost effectiveness, and…

  16. INTERCOMPARISON OF NEAR REAL-TIME MONITORS OF PM2.5 NITRATE AND SULFATE AT THE U.S. ENVIRONMENTAL PROTECTION AGENCY ATLANTA SUPERSITE

    EPA Science Inventory

    Five new instruments for semi-continuous measurements of fine particle (PM2.5) nitrate and sulfate were deployed at the Atlanta Supersite Experiment during an intensive study in August 1999. The instruments measured bulk aerosol chemical composition at rates ranging from every...

  17. A Study of the Role of Clouds in the Relationship Between Land Use/Land Cover and the Climate and Air Quality of the Atlanta Area

    NASA Technical Reports Server (NTRS)

    Kidder, Stanley Q.; Hafner, Jan

    2001-01-01

    The goal of Project ATLANTA is to derive a better scientific understanding of how land cover changes associated with urbanization affect climate and air quality. In this project the role that clouds play in this relationship was studied. Through GOES satellite observations and RAMS modeling of the Atlanta area, we found that in Atlanta (1) clouds are more frequent than in the surrounding rural areas; (2) clouds cool the surface by shading and thus tend to counteract the warming effect of urbanization; (3) clouds reflect sunlight, which might other wise be used to produce ozone; and (4) clouds decrease biogenic emission of ozone precursors, and they probably decrease ozone concentration. We also found that mesoscale modeling of clouds, especially of small, summertime clouds, needs to be improved and that coupled mesoscale and air quality models are needed to completely understand the mediating role that clouds play in the relationship between land use/land cover change and the climate and air quality of Atlanta. It is strongly recommended that more cities be studied to strengthen and extend these results.

  18. Ga nanoparticle-enhanced photoluminescence of GaAs

    SciTech Connect

    Kang, M.; Al-Heji, A. A.; Jeon, S.; Wu, J. H.; Lee, J.-E.; Saucer, T. W.; Zhao, L.; Sih, V.; Katzenstein, A. L.; Sofferman, D. L.; Goldman, R. S.

    2013-09-02

    We have examined the influence of surface Ga nanoparticles (NPs) on the enhancement of GaAs photoluminescence (PL) efficiency. We have utilized off-normal focused-ion-beam irradiation of GaAs surfaces to fabricate close-packed Ga NP arrays. The enhancement in PL efficiency is inversely proportional to the Ga NP diameter. The maximum PL enhancement occurs for the Ga NP diameter predicted to maximize the incident electromagnetic (EM) field enhancement. The PL enhancement is driven by the surface plasmon resonance (SPR)-induced enhancement of the incident EM field which overwhelms the SPR-induced suppression of the light emission.

  19. 77 FR 21153 - Georgia Department of Transportation-Abandonment Exemption-in Fulton County, GA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-09

    ... developing the Atlanta BeltLine, an economic development effort that combines transit, green space, trails... rail segments encircling Atlanta's urban core. Specifically, according to GDOT, the West End...

  20. Comparison of trap characteristics between AlGaN/GaN and AlGaN/InGaN/GaN heterostructure by frequency dependent conductance measurement

    SciTech Connect

    Chakraborty, Apurba; Biswas, Dhrubes

    2015-02-23

    Frequency dependent conductance measurement is carried out to observe the trapping effect in AlGaN/InGaN/GaN double heterostructure and compared that with conventional AlGaN/GaN single heterostructure. It is found that the AlGaN/InGaN/GaN diode structure does not show any trapping effect, whereas single heterostructure AlGaN/GaN diode suffers from two kinds of trap energy states in near depletion to higher negative voltage bias region. This conductance behaviour of AlGaN/InGaN/GaN heterostructure is owing to more Fermi energy level shift from trap energy states at AlGaN/InGaN junction compare to single AlGaN/GaN heterostructure and eliminates the trapping effects. Analysis yielded interface trap energy state in AlGaN/GaN is to be with time constant of (33.8–76.5) μs and trap density of (2.38–0.656) × 10{sup 12 }eV{sup −1} cm{sup −2} in −3.2 to −4.8 V bias region, whereas for AlGaN/InGaN/GaN structure no interface energy states are found and the extracted surface trap energy concentrations and time constants are (5.87–4.39) ×10{sup 10} eV{sup −1} cm{sup −2} and (17.8–11.3) μs, respectively, in bias range of −0.8–0.0 V.

  1. Urban airshed modeling of air quality impacts of alternative transportation fuel use in Los Angeles and Atlanta

    SciTech Connect

    1997-12-01

    The main objective of NREL in supporting this study is to determine the relative air quality impact of the use of compressed natural gas (CNG) as an alternative transportation fuel when compared to low Reid vapor pressure (RVP) gasoline and reformulated gasoline (RFG). A table lists the criteria, air toxic, and greenhouse gas pollutants for which emissions were estimated for the alternative fuel scenarios. Air quality impacts were then estimated by performing photochemical modeling of the alternative fuel scenarios using the Urban Airshed Model Version 6.21 and the Carbon Bond Mechanism Version IV (CBM-IV) (Geary et al., 1988) Using this model, the authors examined the formation and transport of ozone under alternative fuel strategies for motor vehicle transportation sources for the year 2007. Photochemical modeling was performed for modeling domains in Los Angeles, California, and Atlanta, Georgia.

  2. 77 FR 24399 - Approval and Promulgation of Implementation Plans; Georgia; Atlanta; Ozone 2002 Base Year...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-24

    ... Base Year Emissions Inventory AGENCY: Environmental Protection Agency (EPA). ACTION: Direct final rule. SUMMARY: EPA is taking direct final action to approve the ozone 2002 base year emissions inventory... FR 23857, April 30, 2004).\\1\\ Ambient air quality monitoring data for the 3-year period must meet...

  3. From Competence to Efficiency: A Tale of GA Progress

    NASA Technical Reports Server (NTRS)

    Goldberg, David E.

    1996-01-01

    Genetic algorithms (GAs) - search procedures based on the mechanics of natural selection and genetics - have grown in popularity for the solution of difficult optimization problems. Concomitant with this growth has been a rising cacaphony of complaint asserting that too much time must be spent by the GA practitioner diddling with codes, operators, and GA parameters; and even then these GA cassandras continue, and the user is still unsure that the effort will meet with success. At the same time, there has been a rising interest in GA theory by a growing community - a theorocracy - of mathematicians and theoretical computer scientists, and these individuals have turned their efforts increasingly toward elegant abstract theorems and proofs that seem to the practitioner to offer little in the way of answers for GA design or practice. What both groups seem to have missed is the largely unheralded 1993 assembly of integrated, applicable theory and its experimental confirmation. This theory has done two key things. First, it has predicted that simple GAs are severely limited in the difficulty of problems they can solve, and these limitations have been confirmed experimentally. Second, it has shown the path to circumventing these limitations in nontraditional GA designs such as the fast messy GA. This talk surveys the history, methodology, and accomplishment of the 1993 applicable theory revolution. After arguing that these accomplishments open the door to universal GA competence, the paper shifts the discussion to the possibility of universal GA efficiency in the utilization of time and real estate through effective parallelization, temporal decomposition, hybridization, and relaxed function evaluation. The presentation concludes by suggesting that these research directions are quickly taking us to a golden age of adaptation.

  4. Modeling highly transient flow, mass, and heat transport in the Chattahoochee River near Atlanta, Georgia

    USGS Publications Warehouse

    Jobson, Harvey E.; Keefer, Thomas N.

    1979-01-01

    A coupled flow-temperature model has been developed and verified for a 27.9-km reach of the Chattahoochee River between Buford Dam and Norcross, Ga. Flow in this reach of the Chattahoochee is continuous but highly regulated by Buford Dam, a flood-control and hydroelectric facility located near Buford, Ga. Calibration and verification utilized two sets of data collected under highly unsteady discharge conditions. Existing solution techniques, with certain minor improvements, were applied to verify the existing technology of flow and transport modeling. The linear, implicit finite-difference flow model was calibrated by use of a depth profile obtained at steady low flow and unsteady flow data obtained in March 1976. During the calibration period, the model was generally able to reproduce observed stages to within 0.15 m and discharges at less than 100 m 3 /s, to within 5 percent. Peak discharges of about 200 m 3 /s were under-estimated by about 20 percent. During the verification period, October 1975, the flow model reproduced observed stage changes to within about 0.15 m, and its timing and over-all performance was considered to be very good. Dye was added to the upstream end of the river reach at a constant rate while the river flow was highly unsteady. The numerical solution of either the conservative or nonconservative form of the mass-transport equation did an excellent job of simulating the observed concentrations of dye in the river. The temperature model was capable of predicting temperature changes through this reach of as large as 5.8?C with a RMS (root-mean-square) error of 0.32?C in October 1975 and 0.20?C in March 1976. Hydropulsation has a significant effect on the water temperature below Buford Dam. These effects are very complicated because they are quite dependent on the timing of the release with respect to both the time of day and past releases.

  5. The Risk of West Nile Virus Infection Is Associated with Combined Sewer Overflow Streams in Urban Atlanta, Georgia, USA

    PubMed Central

    Vazquez-Prokopec, Gonzalo M.; Vanden Eng, Jodi L.; Kelly, Rosmarie; Mead, Daniel G.; Kolhe, Priti; Howgate, James; Kitron, Uriel; Burkot, Thomas R.

    2010-01-01

    Background At present, the factors favoring transmission and amplification of West Nile Virus (WNV) within urban environments are poorly understood. In urban Atlanta, Georgia, the highly polluted waters of streams affected by combined sewer overflow (CSO) represent significant habitats for the WNV mosquito vector Culex quinquefasciatus. However, their contribution to the risk of WNV infection in humans and birds remains unclear. Objectives Our goals were to describe and quantify the spatial distribution of WNV infection in mosquitoes, humans, and corvids, such as blue jays and American crows that are particularly susceptible to WNV infection, and to assess the relationship between WNV infection and proximity to CSO-affected streams in the city of Atlanta, Georgia. Materials and methods We applied spatial statistics to human, corvid, and mosquito WNV surveillance data from 2001 through 2007. Multimodel analysis was used to estimate associations of WNV infection in Cx. quinquefasciatus, humans, and dead corvids with selected risk factors including distance to CSO streams and catch basins, land cover, median household income, and housing characteristics. Results We found that WNV infection in mosquitoes, corvids, and humans was spatially clustered and statistically associated with CSO-affected streams. WNV infection in Cx. quinquefasciatus was significantly higher in CSO compared with non-CSO streams, and WNV infection rates among humans and corvids were significantly associated with proximity to CSO-affected streams, the extent of tree cover, and median household income. Conclusions Our study strongly suggests that CSO-affected streams are significant sources of Cx. quinquefasciatus mosquitoes that may facilitate WNV transmission to humans within urban environments. Our findings may have direct implications for the surveillance and control of WNV in other urban centers that continue to use CSO systems as a waste management practice. PMID:20529765

  6. PM emissions measurements of in-service commercial aircraft engines during the Delta-Atlanta Hartsfield Study

    NASA Astrophysics Data System (ADS)

    Lobo, Prem; Hagen, Donald E.; Whitefield, Philip D.; Raper, David

    2015-03-01

    This paper describes the results of the physical characterization of aircraft engine PM emission measurements conducted during the Delta-Atlanta Hartsfield Study at the Hartsfield-Jackson Atlanta International Airport. Engine exit plane PM emissions were sampled from on-wing engines on several in-service commercial transport aircraft from the fleet of Delta Airlines. The size distributions were lognormal in nature with a single mode. The geometric mean diameter was found to increase with increasing engine thrust, ranging from 15 nm at idle to 40 nm at takeoff. PM number- and mass-based emission indices were observed to be higher at the idle conditions (4% and 7%), lowest at 15%-30% thrust, and then increase with increasing thrust. Emissions measurements were also conducted during an advected plume study where over 300 exhaust plumes generated by a broad mix of commercial transports were sampled 100-350 m downwind from aircraft operational runways during normal airport operations. The range of values measured at take-off for the different engine types in terms of PM number-based emission index was between 7 × 1015-9 × 1017 particles/kg fuel burned, and that for PM mass-based emission index was 0.1-0.6 g/kg fuel burned. PM characteristics of aircraft engine specific exhaust were found to evolve over time as the exhaust plume expands, dilutes with ambient air, and cools. The data from these measurements will enhance the emissions inventory development for a subset of engines operating in the commercial fleet and improve/validate current environmental impact predictive tools with real world aircraft engine specific PM emissions inputs.

  7. Investigation Into the Use of Satellite Data in Aiding Characterization of Particulate Air Quality in the Atlanta, Georgia Metropolitan Area

    NASA Technical Reports Server (NTRS)

    Alston, Erica J.; Sokolik, Irina, N.; Doddridge, Bruce G.

    2011-01-01

    Poor air quality episodes occur often in metropolitan Atlanta, Georgia. The primary focus of this research is to assess the capability of satellites as a tool in characterizing air quality in Atlanta. Results indicate that intra-city PM2.5 concentrations show similar patterns as other U.S. urban areas, with the highest concentrations occurring within the city. Both PM2.5 and MODIS AOD show more increases in the summer than spring, yet MODIS AOD doubles in the summer unlike PM2.5. A majority of OMI AI is below 0.5. Using this value as an ambient measure of carbonaceous aerosols in the urban area, aerosol transport events can be identified. Our results indicate that MODIS AOD is well correlated with PM2.5 on a yearly and seasonal basis with correlation coefficients as high as 0.8 for Terra and 0.7 for Aqua. A possible alternative view of the PM2.5 and AOD relationship is seen through the use of AOD thresholds. These probabilistic thresholds provide a means to describe the AQI through the use of past AOD for a specific area. We use the NAAQS to classify the AOD into different AQI codes, and probabilistically determine thresholds of AOD that represent the majority of a specific AQI category. For example, the majority 80% of moderate AQI days have AOD values between 0.5 - 0.6. The development of thresholds could be a tool used to evaluate air quality from the use of satellites in regions where there are sparse ground-based measurements of PM2.5.

  8. Comparative investigation of InGaP/GaAs/GaAsBi and InGaP/GaAs heterojunction bipolar transistors

    SciTech Connect

    Wu, Yi-Chen; Tsai, Jung-Hui; Chiang, Te-Kuang; Wang, Fu-Min

    2015-10-15

    In this article the characteristics of In{sub 0.49}Ga{sub 0.51}P/GaAs/GaAs{sub 0.975}Bi{sub 0.025} and In{sub 0.49}Ga{sub 0.51}P/GaAs heterojunction bipolar transistor (HBTs) are demonstrated and compared by two-dimensional simulated analysis. As compared to the traditional InGaP/GaAs HBT, the studied InGaP/GaAs/GaAsBi HBT exhibits a higher collector current, a lower base-emitter (B–E) turn-on voltage, and a relatively lower collector-emitter offset voltage of only 7 mV. Because the more electrons stored in the base is further increased in the InGaP/GaAs/GaAsBi HBT, it introduces the collector current to increase and the B–E turn-on voltage to decrease for low input power applications. However, the current gain is slightly smaller than the traditional InGaP/GaAs HBT attributed to the increase of base current for the minority carriers stored in the GaAsBi base.

  9. 29 CFR 1610.4 - Public reference facilities and current index.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., Albuquerque, NM 87102. Atlanta District Office, 100 Alabama Street, SW., Suite 4R30, Atlanta, GA 30303...-8001. Savannah Local Office (Atlanta District), 410 Mall Boulevard, Suite G, Savannah, GA...

  10. Carrier spin relaxation in GaInNAsSb/GaNAsSb/GaAs quantum well

    SciTech Connect

    Asami, T.; Nosho, H.; Tackeuchi, A.; Li, L. H.; Harmand, J. C.; Lu, S. L.

    2011-12-23

    We have investigated the carrier spin relaxation in GaInNAsSb/GaNAsSb/GaAs quantum well (QW) by time-resolved photoluminescence (PL) measurement. The sample consists of an 8-nm-thick GaIn{sub 0.36}N{sub 0.006}AsSb{sub 0.015} well, 5-nm-thick GaN{sub 0.01}AsSb{sub 0.11} intermediate barriers and 100-nm-thick GaAs barriers grown by molecular beam epitaxy on a GaAs(100) substrate. The spin relaxation time and recombination lifetime at 10 K are measured to be 228 ps and 151 ps, respectively. As a reference, we have also obtained a spin relaxation time of 125 ps and a recombination lifetime of 63 ps for GaInNAs/GaNAs/GaAs QW. This result shows that crystal quality is slightly improved by adding Sb, although these short carrier lifetimes mainly originate from a nonradiative recombination. These spin relaxation times are longer than the 36 ps spin relaxation time of InGaAs/InP QWs and shorter than the 2 ns spin relaxation time of GaInNAs/GaAs QW.

  11. [Pupil Performance in the Elementary Schools of Atlanta, Ga.] Research and Development Report, Volume 6, Numbers 15, 16, and 19, December 1972, March 1973.

    ERIC Educational Resources Information Center

    Vivona, Carol; And Others

    Since a large number of the pupils at each of the three schools examined in this document had shown a need for compensatory services, they were classified as Title I schools and thus were qualified to receive supplementary funds and additional personnel through Title I, 1965 Elementary and Secondary Education Act grant allocations. In addition,…

  12. Gas-solid flows - 1986; Proceedings of the Fourth Fluid Mechanics, Plasma Dynamics, and Lasers Conference, Atlanta, GA, May 11-14, 1986

    NASA Astrophysics Data System (ADS)

    Jurewicz, J. T.

    Papers are presented on deposition and resuspension of gas-borne particles in recirculating turbulent flows, particle dispersion in decaying isotropic homogeneous turbulence, turbulent dispersion of droplets for air flow in a pipe, a comparison between Lagrangian and Eulerian model approaches to turbulent particle dispersion, and the effect of turbulent electrohydrodynamics on electrostatic precipitator efficiency. Also considered are errors due to turbidity in particle sizing using laser Doppler velocimetry, particle motion in a fluidically oscillating jet, high pressure steam/water jet measurements using a portable particle sizing laser Doppler system, the effect of particle shape on pressure drop in a turbulent gas/solid suspension, and the experimental study of gas solid flows in pneumatic conveying. Other topics include entropy production and pressure loss in gas-solid flows, a computational study of turbulent gas-particle flow in a Venturi, a numerical analysis of confined recirculating gas-solid turbulent flows, nozzle and free jet flows of gas particle mixtures, and particle separation in pulsed airflow. Papers are also presented on sampling of solid particles in clouds, particle motion near the inlet of a sampling probe, the effects of slot injection on blade erosion in direct coal-fueled gas turbines, bed diameter effects and incipient slugging in gas fluidized beds, and sedimentation of air fluidized fine graphite particles by methanol vapor.

  13. ASSOCIATIONS BETWEEN OUTDOOR PARTICULATE (PM2.5) CONCENTRATIONS AND GASEOUS CO-POLLUTANT EXPOSURE LEVELS FOR COPD AND MI COHORTS IN ATLANTA, GA

    EPA Science Inventory

    Epidemiological studies indicate that daily ambient particulate matter (PM2.5) concentrations are associated with increased mortality, hospital admissions, and respiratory and cardiovascular effects. It is possible that the observed significant associations are the result of c...

  14. [Pupil Performance in the Elementary Schools of Atlanta, Ga.] Research and Development Report, Volume VI, Numbers 24 and 34. April and May 1973.

    ERIC Educational Resources Information Center

    Atlanta Public Schools, GA.

    Part one of this two-part report focuses on the supplementary programs, partially funded under Titles I and IV of the 1965 Elementary Secondary Education Act, at Mary McLeod Bethune Elementary School. The faculty at Bethune chose to focus on the primary clusters--kindergarten, first, second, and third grades--for evaluation. Special emphasis was…

  15. Life Options for Exceptional Individuals. Conference Proceedings of the International Conference of the Division on Career Development (5th, Atlanta, GA, October 12-14, 1989).

    ERIC Educational Resources Information Center

    Council for Exceptional Children, Reston, VA. Div. on Career Development.

    Seven papers are presented which illustrate model programs and research on providing vocational services to students with disabilities. "Project WorkAbility: California's Successful Transition Program for Secondary Students" (Deborah Henderson) describes locally controlled transition projects involving interagency collaboration and statewide…

  16. AlGaAs/InGaAlP tunnel junctions for multijunction solar cells

    SciTech Connect

    SHARPS,P.R.; LI,N.Y.; HILLS,J.S.; HOU,H.; CHANG,PING-CHIH; BACA,ALBERT G.

    2000-05-16

    Optimization of GaInP{sub 2}/GaAs dual and GaInP{sub 2}/GaAs/Ge triple junction cells, and development of future generation monolithic multi-junction cells will involve the development of suitable high bandgap tunnel junctions. There are three criteria that a tunnel junction must meet. First, the resistance of the junction must be kept low enough so that the series resistance of the overall device is not increased. For AMO, 1 sun operation, the tunnel junction resistance should be below 5 x 10{sup {minus}2} {Omega}-cm. Secondly, the peak current density for the tunnel junction must also be larger than the J{sub sc} of the cell so that the tunnel junction I-V curve does not have a deleterious effect on the I-V curve of the multi-junction device. Finally, the tunnel junction must be optically transparent, i.e., there must be a minimum of optical absorption of photons that will be collected by the underlying subcells. The paper reports the investigation of four high bandgap tunnel junctions grown by metal-organic chemical vapor deposition.

  17. Electrical detection of biomaterials using AlGaN/GaN high electron mobility transistors

    NASA Astrophysics Data System (ADS)

    Kang, B. S.; Wang, H. T.; Ren, F.; Pearton, S. J.

    2008-08-01

    Chemical sensors can be used to analyze a wide variety of environmental and biological gases and liquids and may need to be able to selectively detect a target analyte. Different methods, including gas chromatography, chemiluminescence, selected ion flow tube, and mass spectroscopy, have been used to measure biomarkers. These methods show variable results in terms of sensitivity for some applications and may not meet the requirements for a handheld biosensor. A promising sensing technology utilizes AlGaN/GaN high electron mobility transistors (HEMTs). HEMT structures have been developed for use in microwave power amplifiers due to their high two dimensional electron gas (2DEG) mobility and saturation velocity. The conducting 2DEG channel of AlGaN/GaN HEMTs is very close to the surface and extremely sensitive to adsorption of analytes. HEMT sensors can be used for detecting gases, ions, pH values, proteins, and DNA. In this paper we review recent progress on functionalizing the surface of HEMTs for specific detection of glucose, kidney marker injury molecules, prostate cancer, and other common substances of interest in the biomedical field.

  18. Calibration of visual model for space manipulator with a hybrid LM-GA algorithm

    NASA Astrophysics Data System (ADS)

    Jiang, Wensong; Wang, Zhongyu

    2016-01-01

    A hybrid LM-GA algorithm is proposed to calibrate the camera system of space manipulator to improve its locational accuracy. This algorithm can dynamically fuse the Levenberg-Marqurdt (LM) algorithm and Genetic Algorithm (GA) together to minimize the error of nonlinear camera model. LM algorithm is called to optimize the initial camera parameters that are generated by genetic process previously. Iteration should be stopped if the optimized camera parameters meet the accuracy requirements. Otherwise, new populations are generated again by GA and optimized afresh by LM algorithm until the optimal solutions meet the accuracy requirements. A novel measuring machine of space manipulator is designed to on-orbit dynamic simulation and precision test. The camera system of space manipulator, calibrated by hybrid LM-GA algorithm, is used for locational precision test in this measuring instrument. The experimental results show that the mean composite errors are 0.074 mm for hybrid LM-GA camera calibration model, 1.098 mm for LM camera calibration model, and 1.202 mm for GA camera calibration model. Furthermore, the composite standard deviations are 0.103 mm for the hybrid LM-GA camera calibration model, 1.227 mm for LM camera calibration model, and 1.351 mm for GA camera calibration model. The accuracy of hybrid LM-GA camera calibration model is more than 10 times higher than that of other two methods. All in all, the hybrid LM-GA camera calibration model is superior to both the LM camera calibration model and GA camera calibration model.

  19. Spatial and temporal variability in nutrient concentrations in surface waters of the Chattahoochee River basin near Atlanta, Georgia, USA

    USGS Publications Warehouse

    Peters, N.E.; Buell, G.R.; Frick, E.A.

    1997-01-01

    Nutrient concentrations from the early 1970s through 1995 were evaluated at several sites along the Chattahoochee River and its tributaries near Atlanta, to determine general patterns and processes controlling nutrient concentrations in the river. A spatial analysis was conducted on data collected in 1994 and 1995 from an intensive nutrient study of the Chattahoochee River and its tributaries by the Georgia Department of Natural Resources, Environmental Protection Division. The 1994-1995 data show step increases in ammonium (NH4-N), nitrite plus nitrate (NO2 + NO3-N), and total-phosphorus (Tot-P) concentrations in the river. The step increases occur downstream of two wastewater treatment facilities (WWTFs) and Peachtree Creek, a small tributary inflow with degraded water quality draining a predominantly urban and industrial area. Median NO2 + NO3-N and Tot-P concentrations in the mainstem increase downstream of these inputs from 0.5 to 1 mg 1-1 and from 0.04 to 0.13 mg 1-1, respectively. NH4-N concentrations were typically low with 95% of the 2575 observations less than 0.2 mg 1-1 throughout the river system, except some high values (>1 mg 1-1) in some tributaries, particularly near the central part of Atlanta. High NH4-N concentrations are attributed to sewage discharge as they also are associated with high biological oxygen demand and faecal coliform bacteria concentrations. Nutrient concentrations vary temporally. An assessment of four sites, two mainstem and two tributaries, from 1970 to 1995 indicates a progressive increase and variability in NO2 + NO3-N concentrations during the period. The progressive increase in NO2 + NO3-N concentrations and their variability is similar to that reported for surface waters throughout the world and for which increased fertilizer usage has been attributed. Tot-P concentrations increase at mainstem sites through the middle to late 1980s and decrease markedly thereafter, due to improvements to WWTFs and a 1990 phosphate

  20. Effect of the restricted use of phosphate detergent and upgraded wastewater-treatment facilities of water quality in the Chattahoochee River near Atlanta, Georgia

    USGS Publications Warehouse

    Wangsness, D.J.; Frick, E.A.; Buell, G.R.; DeVivo, J.C.

    1994-01-01

    Data compiled for the six largest waste-water treatment facilities in Metropolitan Atlanta, Georgia, indicate about an 83-percent reduction in the phosphorus load discharged to the Chattahoochee River from 1988 to 1993 because of restricted use of phosphate detergents and upgraded treatment of municipal wastewater. This reduction resulted in about a 54-percent decrease in the phosphorus load in the Chattahoochee River downstream of Atlanta during this time period. Phosphorus loads in animal manure and fertilizers applied to the land (nonpoint sources) are greater than loads discharged to the Chattahoochee River from wastewater-treatment facilities (point sources). However, only a fraction of the phosphorus applied to the land enters the surface waters and is bioavailable. Even though nonpoint sources of land applied phosphorus potentially are important sources to surface waters, point-source inputs from wastewater effluent are far greater. Phosphorus concentrations in wastewater effluent from three cities of Atlanta waste-water treatment facilities need to be reduced by about an additional 31 percent by 1996 to comply with Georgia Department of Natural Resources Environmental Protection Division regulations.

  1. Reverse bias leakage current mechanism of AlGaN/InGaN/GaN heterostructure

    NASA Astrophysics Data System (ADS)

    Chakraborty, Apurba; Ghosh, Saptarsi; Mukhopadhyay, Partha; Jana, Sanjay K.; Dinara, Syed Mukulika; Bag, Ankush; Mahata, Mihir K.; Kumar, Rahul; Das, Subhashis; Das, Palash; Biswas, Dhrubes

    2016-03-01

    The reverse bias leakage current mechanism of AlGaN/InGaN/GaN heterostructure is investigated by current-voltage measurement in temperature range from 298 K to 423 K. The Higher electric field across the AlGaN barrier layer of AlGaN/InGaN/GaN double heterostructure due to higher polarization charge is found to be responsible for strong Fowler-Nordheim (FN) tunnelling in the electric field higher than 3.66 MV/cm. For electric field less than 3.56 MV/cm, the reverse bias leakage current is also found to follow the trap assisted Frenkel-Poole (FP) emission in low negative bias region. Analysis of reverse FP emission yielded the barrier height of trap energy level of 0.34 eV with respect to Fermi level. [Figure not available: see fulltext.

  2. Moth eye antireflection coated GaInP/GaAs/GaInNAs solar cell

    NASA Astrophysics Data System (ADS)

    Aho, Arto; Tommila, Juha; Tukiainen, Antti; Polojärvi, Ville; Niemi, Tapio; Guina, Mircea

    2014-09-01

    The performance of a GaInP/GaAs/GaInNAs solar cell incorporating AlInP moth eye antireflection coating is reported and compared with the performance of a similar cell comprising TiO2/SiO2 antireflection coating. The moth eye coating exhibits an average reflectance of only 2% within the spectral range from 400 nm to 1600 nm. EQE measurements revealed absorption-related losses in the AlInP moth eye coating at wavelengths below 510 nm. Short wavelength absorption decreases the current generation in the top GaInP junction by 10%. Despite the absorption losses, the moth eye patterned GaInP/GaAs/GaInNAs solar cell exhibited higher current generation under AM1.5G real sun illumination.

  3. Investigation of the GaN-on-GaAs interface for vertical power device applications

    SciTech Connect

    Möreke, Janina Uren, Michael J.; Kuball, Martin; Novikov, Sergei V.; Foxon, C. Thomas; Hosseini Vajargah, Shahrzad; Wallis, David J.; Humphreys, Colin J.; Haigh, Sarah J.; Al-Khalidi, Abdullah; Wasige, Edward; Thayne, Iain

    2014-07-07

    GaN layers were grown onto (111) GaAs by molecular beam epitaxy. Minimal band offset between the conduction bands for GaN and GaAs materials has been suggested in the literature raising the possibility of using GaN-on-GaAs for vertical power device applications. I-V and C-V measurements of the GaN/GaAs heterostructures however yielded a rectifying junction, even when both sides of the junction were heavily doped with an n-type dopant. Transmission electron microscopy analysis further confirmed the challenge in creating a GaN/GaAs Ohmic interface by showing a large density of dislocations in the GaN layer and suggesting roughening of the GaN/GaAs interface due to etching of the GaAs by the nitrogen plasma, diffusion of nitrogen or melting of Ga into the GaAs substrate.

  4. On the dissolution properties of GaAs in Ga

    NASA Technical Reports Server (NTRS)

    Davidson, M. C.; Moynahan, A. H.

    1977-01-01

    The dissolution of GaAs in Ga was studied to determine the nature and cause of faceting effects. Ga was allowed to dissolve single crystalline faces under isothermal conditions. Of the crystalline planes with low number indices, only the (100) surface showed a direct correlation of dissolution sites to dislocations. The type of dissolution experienced depended on temperature, and there were three distinct types of behavior.

  5. Meeting Demand.

    ERIC Educational Resources Information Center

    Daneman, Kathy

    1998-01-01

    Addresses how a school district can use temporary classroom space to meet increasing student enrollment while additional space is being built. Provides examples of using portable facilities to supplement educational sites, including how to protect students who are in portable classrooms when tornadoes appear. (GR)

  6. GaN High Power Devices

    SciTech Connect

    PEARTON,S.J.; REN,F.; ZHANG,A.P.; DANG,G.; CAO,X.A.; LEE,K.P.; CHO,H.; GILA,B.P.; JOHNSON,J.W.; MONIER,C.; ABERNATHY,C.R.; HAN,JUNG; BACA,ALBERT G.; CHYI,J.-I.; LEE,C.-M.; NEE,T.-E.; CHUO,C.-C.; CHI,G.C.; CHU,S.N.G.

    2000-07-17

    A brief review is given of recent progress in fabrication of high voltage GaN and AlGaN rectifiers, GaN/AlGaN heterojunction bipolar transistors, GaN heterostructure and metal-oxide semiconductor field effect transistors. Improvements in epitaxial layer quality and in fabrication techniques have led to significant advances in device performance.

  7. Long-term trends and weekday-to-weekend differences in ozone, its precursors, and other secondary pollutants in Atlanta, Georgia

    NASA Astrophysics Data System (ADS)

    Pollack, I. B.; Ryerson, T. B.; Baumann, K.; Edgerton, E. S.; De Gouw, J. A.; Gilman, J.; Graus, M.; Holloway, J.; Lerner, B. M.; Neuman, J. A.; Roberts, J. M.; Veres, P. R.; Warneke, C.; Trainer, M.; Parrish, D. D.

    2013-12-01

    In an environment rich in biogenic volatile organic compounds (VOCs), decreasing concentrations of ozone (-1.3 % yr-1) and other secondary pollutants (-8.2 % yr-1 for nitric acid, HNO3; and -7.9 % yr-1 for peroxyacetyl nitrate, PAN) in Atlanta, Georgia over the past fifteen years are primarily attributed to decreases in local emissions of nitrogen oxides (NOx=NO+NO2). Large reductions in abundances of NOx in the Southeast U.S. over the years (-8.0 % yr-1 for total reactive nitrogen, NOy) are the direct result of control strategies implemented to reduced emissions from electric-power generation plants and on-road motor vehicles. Here, we compile an extensive historical data set of trace gas measurements spanning fifteen years between 1998 and 2013 from a surface monitoring network site in downtown Atlanta (i.e. the SEARCH network Jefferson Street site) and research aircraft (e.g. the 2013 Southeast Atmosphere Study and 1999 Southern Oxidants Study aboard the NOAA P-3 aircraft). With this data set we confirm and extend long-term trends and weekday-to-weekend differences in ozone, its precursors, and other secondary pollutants during summertime in Atlanta. Long-term changes in abundances and enhancement ratios of secondary oxidation products indicate changes in pollutant formation chemistry in Atlanta resulting from the significant decrease in NOx precursor emissions over the past fifteen years. The most noteworthy changes include: 1) an increase in enhancement ratios of odd oxygen (Ox=O3+NO2) to (PAN+HNO3) of +5.5 % yr-1 indicating an increase in ozone production efficiency by a factor of 2 over the fifteen year period, 2) no significant change in the fraction of oxidized NOx out of NOy over time indicating little change in the extent of photochemical processing of the NOx emissions, and 3) a flip in observed ozone concentrations from higher average ozone on weekends to higher average ozone on weekdays after 2004. The observations for Atlanta will also be contrasted

  8. Commercial aircraft engine emissions characterization of in-use aircraft at Hartsfield-Jackson Atlanta International Airport.

    PubMed

    Herndon, Scott C; Jayne, John T; Lobo, Prem; Onasch, Timothy B; Fleming, Gregg; Hagen, Donald E; Whitefield, Philip D; Miake-Lye, Richard C

    2008-03-15

    The emissions from in-use commercial aircraft engines have been analyzed for selected gas-phase species and particulate characteristics using continuous extractive sampling 1-2 min downwind from operational taxi- and runways at Hartsfield-Jackson Atlanta International Airport. Using the aircraft tail numbers, 376 plumes were associated with specific engine models. In general, for takeoff plumes, the measured NOx emission index is lower (approximately 18%) than that predicted by engine certification data corrected for ambient conditions. These results are an in-service observation of the practice of "reduced thrust takeoff". The CO emission index observed in ground idle plumes was greater (up to 100%) than predicted by engine certification data for the 7% thrust condition. Significant differences are observed in the emissions of black carbon and particle number among different engine models/technologies. The presence of a mode at approximately 65 nm (mobility diameter) associated with takeoff plumes and a smaller mode at approximately 25 nm associated with idle plumes has been observed. An anticorrelation between particle mass loading and particle number concentration is observed.

  9. Organic compounds assessed in Chattahoochee River water used for public supply near Atlanta, Georgia, 2004-05

    USGS Publications Warehouse

    Hughes, W. Brian; Younker, Cristal L.

    2011-01-01

    An investigation by the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program characterized the occurrence of 266 organic compounds in source water and finished water from the Chattahoochee River, which is the main water-supply source for the Atlanta metropolitan area. Source water is stream water collected at a surface-water intake prior to water treatment, and finished water is water that has passed through treatment processes prior to distribution. Samples were collected approximately monthly during 2004-05 and included 15 paired source-water and finished-water samples. Samples were collected during winter-spring high flow and summer-fall low flow, but storm events were not targeted during this Source Water-Quality Assessment (SWQA) study. Samples were analyzed for pesticides and degradates, gasoline hydrocarbons, solvents, disinfection by-products, personal care and domestic-use products, and other organic compounds. Community water systems are required to monitor regulated organic compounds under the Safe Drinking Water Act of 1996 (U.S. Environmental Protection Agency, 1998); however, most compounds included in this study are not regulated by Federal drinking-water standards (U.S. Environmental Protection Agency, 2007a). The Chattahoochee River study is part of an ongoing NAWQA investigation of community water systems across the United States. Additional details about the national study are given in Carter and others (2007).

  10. Prevalence and Perspectives of Complementary and Alternative Medicine among University Students in Atlanta, Newcastle upon Tyne, and New Delhi.

    PubMed

    Subramanian, Kritika; Midha, Inuka

    2016-01-01

    Objective. A cross-cultural comparative study was developed that surveyed university students in Atlanta (United States), New Delhi (India), and Newcastle upon Tyne (United Kingdom) to understand the prevalence and perspectives of CAM in three urban societies with different healthcare systems. Design. Surveys were sent to students in the three aforementioned cities. Survey distribution occurred over 6 months from May to November 2015. A total of 314 surveys were received. Results. Dietary and vitamin supplements had the highest prevalence collectively (n = 203), followed by meditation, yoga, and massage. Commentary analysis showed the importance of science and evidence in justifying CAM practice. Conclusions. Matching the most prevalent practices with their designated NCCAM categories suggested that the students were attracted to biologically based, body-based, and mind-body practices as the central themes of attraction. Selected and prevalent CAM practices suggested the students' desire to maintain physical and mental fitness. Access to healthcare may have influence on the prevalence of CAM. Indian students were more likely to view CAM as a viable alternative to conventional medicine. PMID:27382643

  11. Prevalence and Perspectives of Complementary and Alternative Medicine among University Students in Atlanta, Newcastle upon Tyne, and New Delhi.

    PubMed

    Subramanian, Kritika; Midha, Inuka

    2016-01-01

    Objective. A cross-cultural comparative study was developed that surveyed university students in Atlanta (United States), New Delhi (India), and Newcastle upon Tyne (United Kingdom) to understand the prevalence and perspectives of CAM in three urban societies with different healthcare systems. Design. Surveys were sent to students in the three aforementioned cities. Survey distribution occurred over 6 months from May to November 2015. A total of 314 surveys were received. Results. Dietary and vitamin supplements had the highest prevalence collectively (n = 203), followed by meditation, yoga, and massage. Commentary analysis showed the importance of science and evidence in justifying CAM practice. Conclusions. Matching the most prevalent practices with their designated NCCAM categories suggested that the students were attracted to biologically based, body-based, and mind-body practices as the central themes of attraction. Selected and prevalent CAM practices suggested the students' desire to maintain physical and mental fitness. Access to healthcare may have influence on the prevalence of CAM. Indian students were more likely to view CAM as a viable alternative to conventional medicine.

  12. Refined assessment of associations between drinking water residence time and emergency department visits for gastrointestinal illness in Metro Atlanta, Georgia.

    PubMed

    Levy, Karen; Klein, Mitchel; Sarnat, Stefanie Ebelt; Panwhar, Samina; Huttinger, Alexandra; Tolbert, Paige; Moe, Christine

    2016-08-01

    Recent outbreak investigations suggest that a substantial proportion of waterborne disease outbreaks are attributable to water distribution system issues. In this analysis, we examine the relationship between modeled water residence time (WRT), a proxy for probability of microorganism intrusion into the distribution system, and emergency department visits for gastrointestinal (GI) illness for two water utilities in Metro Atlanta, USA during 1993-2004. We also examine the association between proximity to the nearest distribution system node, based on patients' residential address, and GI illness using logistic regression models. Comparing long (≥90th percentile) with intermediate WRTs (11th to 89th percentile), we observed a modestly increased risk for GI illness for Utility 1 (OR = 1.07, 95% CI: 1.02-1.13), which had substantially higher average WRT than Utility 2, for which we found no increased risk (OR = 0.98, 95% CI: 0.94-1.02). Examining finer, 12-hour increments of WRT, we found that exposures >48 h were associated with increased risk of GI illness, and exposures of >96 h had the strongest associations, although none of these associations was statistically significant. Our results suggest that utilities might consider reducing WRTs to <2-3 days or adding booster disinfection in areas with longer WRT, to minimize risk of GI illness from water consumption.

  13. Prevalence and Perspectives of Complementary and Alternative Medicine among University Students in Atlanta, Newcastle upon Tyne, and New Delhi

    PubMed Central

    Subramanian, Kritika; Midha, Inuka

    2016-01-01

    Objective. A cross-cultural comparative study was developed that surveyed university students in Atlanta (United States), New Delhi (India), and Newcastle upon Tyne (United Kingdom) to understand the prevalence and perspectives of CAM in three urban societies with different healthcare systems. Design. Surveys were sent to students in the three aforementioned cities. Survey distribution occurred over 6 months from May to November 2015. A total of 314 surveys were received. Results. Dietary and vitamin supplements had the highest prevalence collectively (n = 203), followed by meditation, yoga, and massage. Commentary analysis showed the importance of science and evidence in justifying CAM practice. Conclusions. Matching the most prevalent practices with their designated NCCAM categories suggested that the students were attracted to biologically based, body-based, and mind-body practices as the central themes of attraction. Selected and prevalent CAM practices suggested the students' desire to maintain physical and mental fitness. Access to healthcare may have influence on the prevalence of CAM. Indian students were more likely to view CAM as a viable alternative to conventional medicine. PMID:27382643

  14. Refined assessment of associations between drinking water residence time and emergency department visits for gastrointestinal illness in Metro Atlanta, Georgia.

    PubMed

    Levy, Karen; Klein, Mitchel; Sarnat, Stefanie Ebelt; Panwhar, Samina; Huttinger, Alexandra; Tolbert, Paige; Moe, Christine

    2016-08-01

    Recent outbreak investigations suggest that a substantial proportion of waterborne disease outbreaks are attributable to water distribution system issues. In this analysis, we examine the relationship between modeled water residence time (WRT), a proxy for probability of microorganism intrusion into the distribution system, and emergency department visits for gastrointestinal (GI) illness for two water utilities in Metro Atlanta, USA during 1993-2004. We also examine the association between proximity to the nearest distribution system node, based on patients' residential address, and GI illness using logistic regression models. Comparing long (≥90th percentile) with intermediate WRTs (11th to 89th percentile), we observed a modestly increased risk for GI illness for Utility 1 (OR = 1.07, 95% CI: 1.02-1.13), which had substantially higher average WRT than Utility 2, for which we found no increased risk (OR = 0.98, 95% CI: 0.94-1.02). Examining finer, 12-hour increments of WRT, we found that exposures >48 h were associated with increased risk of GI illness, and exposures of >96 h had the strongest associations, although none of these associations was statistically significant. Our results suggest that utilities might consider reducing WRTs to <2-3 days or adding booster disinfection in areas with longer WRT, to minimize risk of GI illness from water consumption. PMID:27441862

  15. GaInP /GaAs double heterojunction bipolar transistor with GaAs /Al0.11Ga0.89As/GaInP composite collector

    NASA Astrophysics Data System (ADS)

    Poh, Z. S.; Yow, H. K.; Houston, P. A.; Krysa, A. B.; Ong, D. S.

    2006-07-01

    GaInP /GaAs/GaInP double heterojunction bipolar transistor (DHBT) with an Al0.11Ga0.89As layer within lowly doped GaAs-GaInP composite collector was characterized. In comparison to an abrupt GaInP /GaAs/GaInP DHBT with saturation voltages in excess of 20V, current gains of 25 at high biases, and breakdown voltages in the range of 22V, the DHBT incorporating GaAs -Al0.11Ga0.89As-GaInP composite collector has demonstrated lower saturation voltages of less than 6V and high current gains of 50 without compromising the breakdown voltages of the GaInP collector. Al0.11Ga0.89As layer can thus provide an alternative design to effectively minimize the potential spike effects at the GaAs /GaInP heterojunction.

  16. Analysis of InGaN light-emitting diodes with GaN-AlGaN and AlGaN-GaN composition-graded barriers

    SciTech Connect

    Yang, Yujue; Wang, Junxi; Li, Jinmin; Zeng, Yiping

    2014-06-21

    The effects of InGaN-based light-emitting diodes (LEDs) with Al composition increasing and decreasing GaN-AlGaN barriers along the growth direction are studied numerically. Simulation results suggest that the LEDs with GaN-AlGaN composition-decreased barriers show more significant enhancement of light-output power and internal quantum efficiency than LEDs with composition-increasing GaN-AlGaN barriers when compared with the conventional LED with GaN barriers, due to the improvement in hole injection efficiency and electron blocking capability. Moreover, the optical performance is further improved by replacing GaN-AlGaN barriers with AlGaN-GaN barriers of the same Al composition-decreasing range, which are mainly attributed to the modified band diagrams. In addition, the major causes of the different efficiency droop behaviors for all the designed structures are explained by the electron leakage current and the different increase rates of hole concentration with injection current.

  17. On the effect of N-GaN/P-GaN/N-GaN/P-GaN/N-GaN built-in junctions in the n-GaN layer for InGaN/GaN light-emitting diodes.

    PubMed

    Kyaw, Zabu; Zhang, Zi-Hui; Liu, Wei; Tan, Swee Tiam; Ju, Zhen Gang; Zhang, Xue Liang; Ji, Yun; Hasanov, Namig; Zhu, Binbin; Lu, Shunpeng; Zhang, Yiping; Sun, Xiao Wei; Demir, Hilmi Volkan

    2014-01-13

    N-GaN/P-GaN/N-GaN/P-GaN/N-GaN (NPNPN-GaN) junctions embedded between the n-GaN region and multiple quantum wells (MQWs) are systematically studied both experimentally and theoretically to increase the performance of InGaN/GaN light emitting diodes (LEDs) in this work. In the proposed architecture, each thin P-GaN layer sandwiched in the NPNPN-GaN structure is completely depleted due to the built-in electric field in the NPNPN-GaN junctions, and the ionized acceptors in these P-GaN layers serve as the energy barriers for electrons from the n-GaN region, resulting in a reduced electron over flow and enhanced the current spreading horizontally in the n- GaN region. These lead to increased optical output power and external quantum efficiency (EQE) from the proposed device.

  18. Staff meeting

    ScienceCinema

    None

    2016-07-12

    I would like to invite all members of the CERN Personnel to a meeting on Wednesday 16 January 2008 at 3:00 p.m. Main Auditorium (bldg 500) to convey my best wishes for the new year, to review CERN’s activities during 2007 and to present the perspectives for 2008, the year of the LHC start-up. Closed-circuit transmission of the meeting will be available in the Council Chamber and in the AB Auditorium (Meyrin), the AB Auditorium (Prévessin), the IT Auditorium (Bldg. 31) and the AT Auditorium (Bldg. 30). Simultaneous translation into English will be available in the main Auditorium. Best wishes for the festive season! Robert AYMAR

  19. Influence of GaAs surface termination on GaSb/GaAs quantum dot structure and band offsets

    SciTech Connect

    Zech, E. S.; Chang, A. S.; Martin, A. J.; Canniff, J. C.; Millunchick, J. M.; Lin, Y. H.; Goldman, R. S.

    2013-08-19

    We have investigated the influence of GaAs surface termination on the nanoscale structure and band offsets of GaSb/GaAs quantum dots (QDs) grown by molecular-beam epitaxy. Transmission electron microscopy reveals both coherent and semi-coherent clusters, as well as misfit dislocations, independent of surface termination. Cross-sectional scanning tunneling microscopy and spectroscopy reveal clustered GaSb QDs with type I band offsets at the GaSb/GaAs interfaces. We discuss the relative influences of strain and QD clustering on the band offsets at GaSb/GaAs interfaces.

  20. High breakdown voltage in AlGaN/GaN HEMTs using AlGaN/GaN/AlGaN quantum-well electron-blocking layers.

    PubMed

    Lee, Ya-Ju; Yao, Yung-Chi; Huang, Chun-Ying; Lin, Tai-Yuan; Cheng, Li-Lien; Liu, Ching-Yun; Wang, Mei-Tan; Hwang, Jung-Min

    2014-01-01

    In this paper, we numerically study an enhancement of breakdown voltage in AlGaN/GaN high-electron-mobility transistors (HEMTs) by using the AlGaN/GaN/AlGaN quantum-well (QW) electron-blocking layer (EBL) structure. This concept is based on the superior confinement of two-dimensional electron gases (2-DEGs) provided by the QW EBL, resulting in a significant improvement of breakdown voltage and a remarkable suppression of spilling electrons. The electron mobility of 2-DEG is hence enhanced as well. The dependence of thickness and composition of QW EBL on the device breakdown is also evaluated and discussed.

  1. High breakdown voltage in AlGaN/GaN HEMTs using AlGaN/GaN/AlGaN quantum-well electron-blocking layers

    PubMed Central

    2014-01-01

    In this paper, we numerically study an enhancement of breakdown voltage in AlGaN/GaN high-electron-mobility transistors (HEMTs) by using the AlGaN/GaN/AlGaN quantum-well (QW) electron-blocking layer (EBL) structure. This concept is based on the superior confinement of two-dimensional electron gases (2-DEGs) provided by the QW EBL, resulting in a significant improvement of breakdown voltage and a remarkable suppression of spilling electrons. The electron mobility of 2-DEG is hence enhanced as well. The dependence of thickness and composition of QW EBL on the device breakdown is also evaluated and discussed. PMID:25206318

  2. GaN/InGaN avalanche phototransistors

    NASA Astrophysics Data System (ADS)

    Shen, Shyh-Chiang; Kao, Tsung-Ting; Kim, Hee-Jin; Lee, Yi-Che; Kim, Jeomoh; Ji, Mi-Hee; Ryou, Jae-Hyun; Detchprohm, Theeradetch; Dupuis, Russell D.

    2015-03-01

    We report on III-nitride (III-N) avalanche phototransistor (APT) action by illuminating ultraviolet (UV) photons onto a GaN/InGaN npn heterojunction bipolar transistor in an open-base configuration. A high responsivity of >1 A/W was measured for the device operating at a collector-to-emitter voltage (VCE) of <15 V in the phototransistor mode. The carrier multiplication in the reversed biased collector leads to a photocurrent avalanche as VCE increases. At λ = 380 nm, the GaN/InGaN APT shows a responsivity of >68 A/W at VCE = 95 V. The InGaN APT demonstrates the feasibility of using III-N bipolar transistor structures for high-sensitivity UV photodetection applications.

  3. A comparison of traditional food and health strategies among Taiwanese and Chinese immigrants in Atlanta, Georgia, USA

    PubMed Central

    2013-01-01

    Background Ethnobotanical studies on the use of plants amongst migrant populations are of great relevance to public health. Traditional health strategies, which incorporate plants as medicines, foods, or both – can play an important role in individual well-being. However, at the same time, migrant populations’ traditional knowledge of such practices may be under a state of greater threat of decline due to factors such as limited access to the plant materials and physical isolation from the homeland, which serves as the primary living reservoir for this knowledge. Methods In this study, we conducted a medical ethnobotanical survey focusing on a comparison of local medicinal food and health strategies with members of two Asian immigrant populations in metro-Atlanta: Chinese and Taiwanese. Snowball sampling techniques were employed to recruit 83 study participants, 57 of which were included in the final analysis. Semi-structured interview techniques were used to question participants about their beliefs and usage of the yin yang system, usage of Chinese herbs and medicinal foods, preference and usage of Eastern and Western medicines, and gardening for medicinal foods. Results and conclusion Comparison of the two groups demonstrated a remarkable difference in health strategies concerning medicinal plant use, including statistically significant differences in beliefs concerning yin and yang, uses of Eastern versus Western medicine, and gardening for medicinal foods. Domestic health strategies in the form of medicinal foods play an important role in local health practices, especially among the Taiwanese participants. The collective desire for the use of both Eastern and Western medicine by both groups highlights the important role that cultural competency training will play in preparing allopathic health practitioners to serve increasingly diverse patient populations in the US. PMID:23981857

  4. Evaluation of two-year Jewish genetic disease screening program in Atlanta: insight into community genetic screening approaches.

    PubMed

    Shao, Yunru; Liu, Shuling; Grinzaid, Karen

    2015-04-01

    Improvements in genetic testing technologies have led to the development of expanded carrier screening panels for the Ashkenazi Jewish population; however, there are major inconsistencies in current screening practices. A 2-year pilot program was launched in Atlanta in 2010 to promote and facilitate screening for 19 Jewish genetic diseases. We analyzed data from this program, including participant demographics and outreach efforts. This retrospective analysis is based on a de-identified dataset of 724 screenees. Data were obtained through medical chart review and questionnaires and included demographic information, screening results, response to outreach efforts, and follow-up behavior and preferences. We applied descriptive analysis, chi-square tests, and logistic regression to analyze the data and compare findings with published literature. The majority of participants indicated that they were not pregnant or did not have a partner who was pregnant were affiliated with Jewish organizations and reported 100 % AJ ancestry. Overall, carrier frequency was 1 in 3.9. Friends, rabbis, and family members were the most common influencers of the decision to receive screening. People who were older, had a history of pregnancy, and had been previously screened were more likely to educate others (all p < 0.05). Analysis of this 2-year program indicated that people who are ready to have children or expand their families are more likely to get screened and encourage others to be screened. The most effective outreach efforts targeted influencers who then encouraged screening in the target population. Educating influencers and increasing overall awareness were the most effective outreach strategies.

  5. Simulating unsteady transport of nitrogen, biochemical oxygen demand, and dissolved oxygen in the Chattahoochee River downstream from Atlanta, Georgia

    USGS Publications Warehouse

    Jobson, Harvey E.

    1985-01-01

    As part of an intensive water-quality assessment of the Chattahoochee River, repetitive water-quality measurements were made at 12 sites along a 69-kilometer reach of the river downstream of Atlanta, Georgia. Concentrations of seven constituents (temperature, dissolved oxygen, ultimate carbonaceous biochemical oxygen demand (BOD), organic nitrogen, ammonia, nitrite, and nitrate) were obtained during two periods of 36 hours, one starting on August 30, 1976, and the other starting on May 31, 1977. The study reach contains one large and several small sewage outfalls and receives the cooling water from two large powerplants. An unsteady water-quality model of the Lagrangian type was calibrated using the 1977 data and verified using the 1976 data. The model provided a good means of interpreting these data even though both the flow and the pollution loading rates were highly unsteady. A kinetic model of the cascade type accurately described the physical and biochemical processes occurring in the river. All rate coefficients, except reaeration coefficients and those describing the resuspension of BOD, were fitted to the 1977 data and verified using the 1976 data. The study showed that, at steady low flow, about 38 percent of the BOD settled without exerting an oxygen demand. At high flow, this settled BOD was resuspended and exerted an immediate oxygen demand. About 70 percent of the ammonia extracted from the water column was converted to nitrite, but the fate of the remaining 30 percent is unknown. Photosynthetic production was not an important factor in the oxygen balance during either run.

  6. “Because He Misses His Normal Life Back Home”: Masculinity and Sexual Behavior Among Mexican Migrants in Atlanta, Georgia

    PubMed Central

    Hirsch, Jennifer S.; Muñoz-Laboy, Miguel; Nyhus, Christina M.; Yount, Kathryn M.; Bauermeister, José A.

    2009-01-01

    Context Labor migration presents an important HIV risk context. Effective health promotion begins with understanding cultural and structural influences on sexual risk. Methods This paper presents the quantitative results from a mixed-methods study carried out in 1999 among Mexican migrant men (N=187) in Atlanta, Georgia. The instrument included questions on several domains: Demographic and sexual history, migration motivations, substance use, social support, leisure time practices, and ideas about masculinity, sexuality, and marriage. We created six multivariate regressions to test the association between each of these domains and men's number of partners. Results Greater number of partners was associated with being younger, having fewer years of formal education, and owning a home in Mexico (Model 1); taking more trips to Mexico (Model 2); feeling sex wasn't tied to emotional intimacy and power (Model 3); having a larger social network and fewer frequency of contact with network members (Model 4); having a sex worker as a partner (Model 5); and going out dancing and stripclubs on weekends (Model 6). Conclusion Emergent visions of marriage that include shared sexual intimacy and emotional intimacy and power imply a reorganization of marital sexuality; yet, only those men who emphasize emotional companionship and equity have fewer extramarital sexual partners. An individual-level intervention may be insufficient to transform men's ideas about manhood; programs must acknowledge and target migrant men's social networks and the spaces in which sexual risk may occur. Multilevel strategies, such as the development of more health-enhancing community spaces, active discussions regarding masculinity, and the promotion of safer sexual practices should form part of comprehensive efforts to reduce sexual risk among migrant men. PMID:19291125

  7. Proceedings of the Annual Meeting of the Association for Education in Journalism and Mass Communication (77th, Atlanta, Georgia, August 10-13, 1994). Part IX: Magazines.

    ERIC Educational Resources Information Center

    Association for Education in Journalism and Mass Communication.

    The Magazines section of this collection of conference presentations contains the following 15 papers: "'National Geographic Magazine' and the Vietnam War: Did We Just Get Pretty Pictures?" (John W. Williams); "Free Speech at All Costs: A Short History of 'The Masses'" (Chris Lamb); "Newspapers Locally Edited Magazines Seek Ways to Maintain Place…

  8. National Association for Research in Science Teaching, Annual Meeting (66th, Atlanta, Georgia, April 15-19, 1993). Abstracts of Presented Papers.

    ERIC Educational Resources Information Center

    Gallard, Alejandro Jose, Ed.; De Albuquerque, Haroldo Guerreiro, Ed.

    This book provides titles, author information, and abstracts of presented papers at the 1993 National Association of Research in Science Teaching Conference. The abstracts are divided into the following sections: (1) Alternative Assessment; (2) Approaches to Research; (3) Conceptual Change; (4) Gender and Equity; (5) History, Philosophy, and…

  9. MEETING IN ATLANTA, GA - COMPARATIVE CYTOTOXICITY OF TRIHALOMETHANES (THMs) AND TRIHALONITROMETHANES (THNMs) IN CULTURED NORMAL HUMAN COLON CELLS

    EPA Science Inventory

    Epidemiological studies have linked the consumption of chlorinated surface waters to an increased risk of colorectal cancer. The THMs [trichloromethane, TCM, bromodichloromethane, BDCM, dibromochloromethane, DBCM, and tribromomethane, TBM] comprise a major class of by-products (D...

  10. Proceedings of the Annual Meeting of the Association for Education in Journalism and Mass Communication (77th, Atlanta, Georgia, August 10-13, 1994). Part X: Miscellaneous Studies.

    ERIC Educational Resources Information Center

    Association for Education in Journalism and Mass Communication.

    The Miscellaneous Studies section of this collection of conference presentations contains the following 22 papers: "Men and Women Journalists in the Movies: Exploration of Some Sexism and Gender Issues in Their Portrayals in Eleven Films" (Albert D. Talbott); "Female Archetypes in Late '80s Films" (Fakhri Haghani); "Chain Ownership, Organizational…

  11. Proceedings of the Annual Meeting of the Association for Education in Journalism and Mass Communication (77th, Atlanta, Georgia, August 10-13, 1994). Part IV: International Media.

    ERIC Educational Resources Information Center

    Association for Education in Journalism and Mass Communication.

    The International Media section of this collection of conference presentations contains the following 15 papers: "Testing the Interaction of the Third-Person Effect and Spiral of Silence in a Political Pressure Cooker: The Case of Hong Kong" (Lars Willnat); "The Use of Small State Variables in Research on Coverage of Foreign Policy: New Zealand…

  12. Proceedings of the Annual Meeting of the Association for Education in Journalism and Mass Communication (77th, Atlanta, Georgia, August 10-13, 1994). Part I: Media History.

    ERIC Educational Resources Information Center

    Association for Education in Journalism and Mass Communication.

    The Media History section of this collection of conference presentations contains the following 21 papers: "Social Class Advocacy Journalism: Prelude to Party Politics, 1892" (David J. Vergobbi); "Pilfering the News: A Quality Comparison of the World and Journal's Spanish-American War Coverage" (Randall S. Sumpter); "The Early Black Press in…

  13. Projecting Future Urbanization with Prescott College's Spatial Growth Model to Promote Environmental Sustainability and Smart Growth, A Case Study in Atlanta, Georgia

    NASA Technical Reports Server (NTRS)

    Estes, Maurice G., Jr.; Crosson, William; Limaye, Ashutosh; Johnson, Hoyt; Quattrochi, Dale; Lapenta, William; Khan, Maudood

    2006-01-01

    Planning is an integral element of good management and necessary to anticipate events not merely respond to them. Projecting the quantity and spatial distribution of urban growth is essential to effectively plan for the delivery of city services and to evaluate potential environmental impacts. The major drivers of growth in large urban areas are increasing population, employment opportunities, and quality of life attractors such as a favorable climate and recreation opportunities. The spatial distribution of urban growth is dictated by the amount and location of developable land, topography, energy and water resources, transportation network, climate change, and the existing land use configuration. The Atlanta region is growing very rapidly both in population and the consumption of forestland or low-density residential development. Air pollution and water availability are significant ongoing environmental issues. The Prescott Spatial Growth Model (SGM) was used to make growth projections for the metropolitan Atlanta region to 2010,2020 and 2030 and results used for environmental assessment in both business as usual and smart growth scenarios. The Prescott SGM is a tool that uses an ESRI ArcView extension and can be applied at the parcel level or more coarse spatial scales and can accommodate a wide range of user inputs to develop any number of growth rules each of which can be weighted depending on growth assumptions. These projections were used in conjunction with meteorological and air quality models to evaluate future environmental impacts. This presentation will focus on the application of the SGM to the 13-County Atlanta Regional Commission planning jurisdiction as a case study. The SGM will be described, including how rule sets are developed and the decision process for allocation of future development to available land use categories. Data inputs required to effectively run the model will be discussed. Spatial growth projections for ten, twenty, and thirty

  14. Monitoring urban impacts on suspended sediment, trace element, and nutrient fluxes within the City of Atlanta, Georgia, USA: Program design, methodological considerations, and initial results

    USGS Publications Warehouse

    Horowitz, A.J.; Elrick, K.A.; Smith, J.J.

    2008-01-01

    Atlanta, Georgia (City of Atlanta, COA), is one of the most rapidly growing urban areas in the US. Beginning in 2003, the US Geological Survey established a long-term water-quantity/quality monitoring network for the COA. The results obtained during the first 2 years have provided insights into the requirements needed to determine the extent of urban impacts on water quality, especially in terms of estimating the annual fluxes of suspended sediment, trace/major elements, and nutrients. During 2004/2005, suspended sediment fluxes from the City of Atlanta (COA) amounted to about 150 000 t year-1; ??? 94% of the transport occurred in conjunction with storm-flow, which also accounted for ??? 65% of the annual discharge. Typically, storm-flow averaged ??? 20% of theyear. Normally, annual suspended sediment fluxes are determined by summing daily loads based on a single calculation step using mean-daily discharge and a single rating curve-derived suspended sediment concentration. Due to the small and 'flashy' nature of the COAs streams, this approach could produce underestimates ranging from 25% to 64%. Accurate estimates (?? 15%) require calculation time-steps as short as every 2-3 h. Based on annual median base-flow/storm-flow chemical concentrations, the annual fluxes of ??? 75% of trace elements (e.g. Cu, Pb, Zn), major elements (e.g. Fe, Al), and total P occur in association with suspended sediment; in turn, ??? 90% of the transport of these constituents occur in conjunction with storm-flow. As such, base-flow sediment-associated and dissolved contributions represent relatively insignificant portions of the total annual load. An exception is total N, whose sediment-associated fluxes range from 50% to 60%; even so, storm-related transport typically exceeds 80%. Hence, in urban environments, non-point-source appear to be the dominant contributors to the fluxes of these constituents.

  15. 30% Efficient InGaP/GaAs/GaSb Cell-Interconnected-Circuits For Line-Focus Concentrator Arrays

    NASA Technical Reports Server (NTRS)

    Fraas, Lewis; Avery, James; Iles, Peter; Chu, Charlie; Piszczor, Mike

    2005-01-01

    In 1989, Fraas and Avery demonstrated a world-record 31% efficient AM0 GaAs/GaSb tandem solar cell. This record efficiency still holds today. However, the GaAs/GaSb mechanical-stacked cell was designed to work with concentrated sunlight and at that time, the space community had no experience with concentrated sunlight solar arrays.

  16. Trends in on-road vehicle emissions and ambient air quality in Atlanta, Georgia, USA, from the late 1990s through 2009.

    PubMed

    Vijayaraghavan, Krish; DenBleyker, Allison; Ma, Lan; Lindhjem, Chris; Yarwood, Greg

    2014-07-01

    On-road vehicle emissions of carbon monoxide (CO), nitrogen oxides (NO(x)), and volatile organic compounds (VOCs) during 1995-2009 in the Atlanta Metropolitan Statistical Area were estimated using the Motor Vehicle Emission Simulator (MOVES) model and data from the National Emissions Inventories and the State of Georgia. Statistically significant downward trends (computed using the nonparametric Theil-Sen method) in annual on-road CO, NO(x), and VOC emissions of 6.1%, 3.3%, and 6.0% per year, respectively, are noted during the 1995-2009 period despite an increase in total vehicle distance traveled. The CO and NO(x) emission trends are correlated with statistically significant downward trends in ambient air concentrations of CO and NO(x) in Atlanta ranging from 8.0% to 11.8% per year and from 5.8% to 8.7% per year, respectively, during similar time periods. Weather-adjusted summertime ozone concentrations in Atlanta exhibited a statistically significant declining trend of 2.3% per year during 2001-2009. Although this trend coexists with the declining trends in on-road NO(x), VOC, and CO emissions, identifying the cause of the downward trend in ozone is complicated by reductions in multiple precursors from different source sectors. Implications: Large reductions in on-road vehicle emissions of CO and NO(x) in Atlanta from the late 1990s to 2009, despite an increase in total vehicle distance traveled, contributed to a significant improvement in air quality through decreases in ambient air concentrations of CO and NO(x) during this time period. Emissions reductions in motor vehicles and other source sectors resulted in these improvements and the observed declining trend in ozone concentrations over the past decade. Although these historical trends cannot be extrapolated to the future because pollutant concentration contributions due to on-road vehicle emissions will likely become an increasingly smaller fraction of the atmospheric total, they provide an indication of

  17. Meeting Venus

    NASA Astrophysics Data System (ADS)

    Sterken, Christiaan; Aspaas, Per Pippin

    2013-06-01

    On 2-3 June 2012, the University of Tromsoe hosted a conference about the cultural and scientific history of the transits of Venus. The conference took place in Tromsoe for two very specific reasons. First and foremost, the last transit of Venus of this century lent itself to be observed on the disc of the Midnight Sun in this part of Europe during the night of 5 to 6 June 2012. Second, several Venus transit expeditions in this region were central in the global enterprise of measuring the scale of the solar system in the eighteenth century. The site of the conference was the Nordnorsk Vitensenter (Science Centre of Northern Norway), which is located at the campus of the University of Tromsoe. After the conference, participants were invited to either stay in Tromsoe until the midnight of 5-6 June, or take part in a Venus transit voyage in Finnmark, during which the historical sites Vardoe, Hammerfest, and the North Cape were to be visited. The post-conference program culminated with the participants observing the transit of Venus in or near Tromsoe, Vardoe and even from a plane near Alta. These Proceedings contain a selection of the lectures delivered on 2-3 June 2012, and also a narrative description of the transit viewing from Tromsoe, Vardoe and Alta. The title of the book, Meeting Venus, refers the title of a play by the Hungarian film director, screenwriter and opera director Istvan Szabo (1938-). The autobiographical movie Meeting Venus (1991) directed by him is based on his experience directing Tannhauser at the Paris Opera in 1984. The movie brings the story of an imaginary international opera company that encounters a never ending series of difficulties and pitfalls that symbolise the challenges of any multicultural and international endeavour. As is evident from the many papers presented in this book, Meeting Venus not only contains the epic tales of the transits of the seventeenth, eighteenth and nineteenth centuries, it also covers the conference

  18. Thickness composition diagrams of Stranski Krastanov mode in the GaPSb/GaP and InGaAs/GaAs systems

    NASA Astrophysics Data System (ADS)

    Nakajima, Kazuo

    1999-06-01

    The strain, surface, and interface energies of the GaPSb/GaP and InGaAs/GaAs systems were calculated for three kinds of pre-determined structure which represent the Frank-van der Merwe (FM), the Stranski-Krastanov (SK), and the Volmer-Weber (VW) modes of epitaxial growth. The free energy for each structure was estimated as a function of thickness and composition or lattice misfit. By comparison of the free energy of each mode, thickness-composition mode diagrams which express the stable region of each mode were determined for the GaPSb/GaP and InGaAs/GaAs(1 1 1) systems. It is found that all three growth modes appear in the mode diagram determined only by the calculation of the free energy. The SK mode appears only when the lattice misfit is large and the layer is thick. The VW mode appears only when the lattice misfit is large and the layer is thin. The SK mode appears in both systems, but the VW mode appears only in the GaPSb/GaP system. The stable region of the SK mode in the mode diagram is wider in the GaPSb/GaP system than that in the InGaAs/GaAs system because the strain energy of the GaPSb/GaP structure increases more strongly as the lattice misfit increases.

  19. Performance improvement of GaN-based LEDs with step stage InGaN/GaN strain relief layers in GaN-based blue LEDs.

    PubMed

    Jia, Chuanyu; Yu, Tongjun; Lu, Huimin; Zhong, Cantao; Sun, Yongjian; Tong, Yuzhen; Zhang, Guoyi

    2013-04-01

    The performance of nitride-based LEDs was improved by inserting dual stage and step stage InGaN/GaN strain relief layer (SRL) between the active layer and n-GaN template. The influences of step stage InGaN/GaN SRL on the structure, electrical and optical characteristics of GaN-based LEDs were investigated. The analysis of strain effect on recombination rate based k·p method indicated 12.5% reduction of strain in InGaN/GaN MQWs by inserting SRL with step stage InGaN/GaN structures. The surface morphology was improved and a smaller blue shift in the electroluminescence (EL) spectral with increasing injection current was observed for LEDs with step stage SRL compared with conventional LEDs. The output power of LEDs operating at 20 mA was about 15.3 mW, increased by more than 108% by using step stage InGaN/GaN SRL, which shows great potential of such InGaN/GaN SRL in modulating InGaN/GaN MQWs optical properties based on its strain relief function.

  20. Oxygen in GaN.

    NASA Astrophysics Data System (ADS)

    van de Walle, Chris G.; Neugebauer, Jörg

    1997-03-01

    Oxygen is commonly present during epitaxial growth of GaN. We have proposed that unintentional incorporation of O, as well as Si, is responsible for the frequently observed n-type conductivity in as-grown GaN. Here we present results from comprehensive density-functional-pseudopotential studies of GaN:O under pressure, and of O interactions with native defects and dopant impurities. We find that the O donor undergoes a DX-like transition under pressure: a large outward relaxation introduces a deep level in the band gap. This behavior explains the carrier freezeout in GaN under pressure.^1 Si donors do not exhibit the transition, consistent with experiment. Results for these impurities in AlGaN will also be discussed. We have also investigated the interaction between O and native defects. Most notably we find a large binding energy between O and the gallium vacancy (V_Ga), which we have proposed to be the source of the yellow luminescence. Finally, we have studied the interaction between O and Mg acceptors. The incorporation of the O donor is significantly enhanced in Mg-doped material. In addition, we calculate a binding energy of 0.6 eV for Mg-O complexes. The presence of O during growth can thus be detrimental to p-type GaN. ^1 C. Wetzel et al., Proc. ICPS-23 (World Scientific, Singapore, 1996), p. 2929.

  1. AlGaAs/InGaAsN/GaAs PnP double heterojunction bipolar transistor

    SciTech Connect

    Chang, P.C.; Baca, A.G.; Li, N.Y.; Sharps, P.R.; Hou, H.Q.; Laroche, J.R.; Ren, F.

    2000-01-04

    The authors demonstrated a functional PnP double heterojunction bipolar transistor (DHBT) using AlGaAs, InGaAsN, and GaAs. The band alignment between InGaAsN and GaAs has a large {triangle}E{sub c} and negligible {triangle}E{sub v}, this unique characteristic is very suitable for PnP DHBT applications. The metalorganic vapor phase epitaxy (MOCVD) grown Al{sub 0.3}Ga{sub 0.7}As/In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01}/GaAs PnP DHBT is lattice matched to GaAs and has a peak current gain of 25. Because of the smaller bandgap (E{sub g}=1.20eV) of In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01} used for the base layer, this device has a low V{sub ON} of 0.79 V, which is 0.25 V lower than in a comparable Pnp AlGaAs/GaAs HBT. And because GaAs is used for the collector, its BV{sub CEO} is 12 V, consistent with BV{sub CEO} of AlGaAs/GaAs HBTs.

  2. Metal–organic molecular beam epitaxy of GaAsNSe films using Ga droplets on GaP(001)

    NASA Astrophysics Data System (ADS)

    Shimomura, Yuki; Igarashi, Yosuke; Kimura, Shinji; Suzuki, Yuhei; Tada, Yoshihiro; Fukuda, Hisashi; Uesugi, Katsuhiro

    2016-08-01

    GaAsNSe films were grown by metal–organic molecular beam epitaxy using Ga droplets prepared on GaP(001) substrates. Ga droplets were formed on Sb-terminated GaP surfaces at a low density of 5.3 × 108 cm‑2 at a substrate temperature of 520 °C. The Ga droplets were ∼63 nm in height and ∼164 nm in diameter. At the initial growth of GaAsNSe on GaP, step-flow growth was promoted by the atomic diffusion from the Ga droplets and flat terraces spread over the surface. Although there was a large lattice mismatch of 3.5% between GaAsNSe and GaP, three-dimensional island growth and pit formation were reduced considerably by the surface diffusion of Ga. In this paper, we report the contribution of Ga droplets to the heterogrowth process of GaAsNSe/GaP.

  3. GaAs AlGaAs intersubband MIR lasers

    NASA Astrophysics Data System (ADS)

    Hvozdara, Lubos; Gianordoli, Stefan; Schrenk, Werner; Strasser, Gottfried; Unterrainer, Karl; Gornik, Erich

    1999-09-01

    We report on the design, growth and characterization of electrically pumped quantum cascade lasers (QCL) and LEDs, based on the GaAs/AlGaAs material system. Intersubband and interminiband optical transitions within the conduction band of a heterostructure are used to achieve spontaneous emission and lasing action. Samples are grown using solid source molecular beam epitaxy. Transport measurements, IR photocurrent spectral response, transmission and emission measurements are performed. Laser wavelength above ten microns are achieved. Peak powers are in the 200 mW range. Laser operation up to 100K and threshold current densities below 15 kA/cm2 are recorded. Ridge lasers exhibit multimode spectra, typical for Fabry-Perot resonators. Room temperature spontaneous emission is recorded, showing the feasibility of a room temperature operating QCL on the GaAs/AlGaAs material system.

  4. Hydrogenation of GaSb/GaAs quantum rings

    SciTech Connect

    Hodgson, P. D. Hayne, M.; Zhuang, Q. D.; Ahmad Kamarudin, M.; Birindelli, S.; Capizzi, M.

    2014-08-25

    We present the results of photoluminescence measurements on hydrogenated type-II GaSb/GaAs quantum dot/ring (QD/QR) samples at temperatures ranging from 4.2 K to 400 K. Hydrogenation is found to suppress optically induced charge depletion (associated with the presence of carbon acceptors in this system). A redshift of the QD\\QR emission energy of a few tens of meV is observed at temperatures ≥300 K, consistent with a reduction in average occupancy by ∼1 hole. These effects are accompanied by a reduction in PL intensity post-hydrogenation. We conclude that although hydrogenation may have neutralized the carbon acceptors, multiple hole occupancy of type-II GaSb/GaAs QD/QRs is very likely a precondition for intense emission, which would make extending the wavelength significantly beyond 1300 nm at room temperature difficult.

  5. AlGaAs-GaAs cascade solar cell

    NASA Technical Reports Server (NTRS)

    Lamorte, M. F.; Abbott, D. H.

    1980-01-01

    Computer modeling studies are reported for a monolithic, two junction, cascade solar cell using the AlGaAs GaAs materials combination. An optimum design was obtained through a serial optimization procedure by which conversion efficiency is maximized for operation at 300 K, AM 0, and unity solar concentration. Under these conditions the upper limit on efficiency was shown to be in excess of 29 percent, provided surface recombination velocity did not exceed 10,000 cm/sec.

  6. GaAs, AlGaAs and InGaP Tunnel Junctions for Multi-Junction Solar Cells Under Concentration: Resistance Study

    SciTech Connect

    Wheeldon, Jeffrey F.; Valdivia, Christopher E.; Walker, Alex; Kolhatkar, Gitanja; Hall, Trevor J.; Hinzer, Karin; Masson, Denis; Riel, Bruno; Fafard, Simon; Jaouad, Abdelatif; Turala, Artur; Ares, Richard; Aimez, Vincent

    2010-10-14

    The following four TJ designs, AlGaAs/AlGaAs, GaAs/GaAs, AlGaAs/InGaP and AlGaAs/GaAs are studied to determine minimum doping concentration to achieve a resistance of <10{sup -4} {omega}{center_dot}cm{sup 2} and a peak tunneling current suitable for MJ solar cells up to 1500-suns concentration (operating current of 21 A/cm{sup 2}). Experimentally calibrated numerical models are used to determine how the resistance changes as a function of doping concentration. The AlGaAs/GaAs TJ design is determined to require the least doping concentration to achieve the specified resistance and peak tunneling current, followed by the GaAs/GaAs, and AlGaAs/AlGaAs TJ designs. The AlGaAs/InGaP TJ design can only achieve resistances >5x10{sup -4} {omega}cm{sup 2}.

  7. Student cognitive growth and attitudinal changes through conducting authentic research in the Young Scientist Program at Zoo Atlanta

    NASA Astrophysics Data System (ADS)

    Sharpe, La Tanya Danielle

    This purpose of this study was to determine if authentic research conducted by students in the Young Scientist Program: (a) enhanced scientific research skills, (b) increased cognitive growth in the areas of animal behavior and characteristics, and (c) affected attitudes toward scientific research, science, and zoo-related issues. During the nine-week program, 18 students from Liberty High School completed program-related activities in their classrooms, and at Zoo Atlanta. Here, students completed authentic research in the form of animal behavior research projects. Research-based activities included forming hypotheses based on animal behavior, creating and maintaining ethograms, and making behavioral observations. This was a mixed method study, in which, both quantitative and qualitative data were collected and analyzed in an attempt to answer the following research questions: (1) How does conducting authentic research within the Young Scientist Program enhance student scientific research skills? (2) How does participation in the Young Scientist Program increase student knowledge of animal behavior and characteristics? (3) How does the Young Scientist Program affect student attitudes? Data were collected pre, mid, and post program. Data sources included: (a) surveys, (b) interviews, (c) student research papers, and (d) researcher field notes. The data were analyzed through a framework of four methodological lenses: (a) knowledge of scientific research, (b) knowledge of animals, (c) attitudes toward scientific research, and (d) attitudes toward science and zoo-related issues. Surveys included knowledge tests and attitude scales. Overall, knowledge test results implied that as students progressed through the Young Scientist Program, their research skills, knowledge of scientific research, and knowledge of their animal were enhanced. Attitudinal data obtained from the attitude scales suggested that students' attitudes toward scientific research, science, and zoo

  8. 86. Photocopy of drawing (February 1994 architectural drawing by Stevens ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    86. Photocopy of drawing (February 1994 architectural drawing by Stevens & Wilkinson, original in possession of Stevens & Wilkinson, Atlanta, George). Rich's Department Store, Atlanta, Georgia, ground floor plan 1924 building. - Rich's Downtown Department Store, 45 Broad Street, Atlanta, Fulton County, GA

  9. Metamorphic GaAs/GaAsBi Heterostructured Nanowires.

    PubMed

    Ishikawa, Fumitaro; Akamatsu, Yoshihiko; Watanabe, Kentaro; Uesugi, Fumihiko; Asahina, Shunsuke; Jahn, Uwe; Shimomura, Satoshi

    2015-11-11

    GaAs/GaAsBi coaxial multishell nanowires were grown by molecular beam epitaxy. Introducing Bi results in a characteristic nanowire surface morphology with strong roughening. Elemental mappings clearly show the formation of the GaAsBi shell with inhomogeneous Bi distributions within the layer surrounded by the outermost GaAs, having a strong structural disorder at the wire surface. The nanowire exhibits a predominantly ZB structure from the bottom to the middle part. The polytipic WZ structure creates denser twin defects in the upper part than in the bottom and middle parts of the nanowire. We observe room temperature cathodoluminescence from the GaAsBi nanowires with a broad spectral line shape between 1.1 and 1.5 eV, accompanied by multiple peaks. A distinct energy peak at 1.24 eV agrees well with the energy of the reduced GaAsBi alloy band gap by the introduction of 2% Bi. The existence of localized states energetically and spatially dispersed throughout the NW are indicated from the low temperature cathodoluminescence spectra and images, resulting in the observed luminescence spectra characterized by large line widths at low temperatures as well as by the appearance of multiple peaks at high temperatures and for high excitation powers.

  10. Metamorphic GaAs/GaAsBi Heterostructured Nanowires.

    PubMed

    Ishikawa, Fumitaro; Akamatsu, Yoshihiko; Watanabe, Kentaro; Uesugi, Fumihiko; Asahina, Shunsuke; Jahn, Uwe; Shimomura, Satoshi

    2015-11-11

    GaAs/GaAsBi coaxial multishell nanowires were grown by molecular beam epitaxy. Introducing Bi results in a characteristic nanowire surface morphology with strong roughening. Elemental mappings clearly show the formation of the GaAsBi shell with inhomogeneous Bi distributions within the layer surrounded by the outermost GaAs, having a strong structural disorder at the wire surface. The nanowire exhibits a predominantly ZB structure from the bottom to the middle part. The polytipic WZ structure creates denser twin defects in the upper part than in the bottom and middle parts of the nanowire. We observe room temperature cathodoluminescence from the GaAsBi nanowires with a broad spectral line shape between 1.1 and 1.5 eV, accompanied by multiple peaks. A distinct energy peak at 1.24 eV agrees well with the energy of the reduced GaAsBi alloy band gap by the introduction of 2% Bi. The existence of localized states energetically and spatially dispersed throughout the NW are indicated from the low temperature cathodoluminescence spectra and images, resulting in the observed luminescence spectra characterized by large line widths at low temperatures as well as by the appearance of multiple peaks at high temperatures and for high excitation powers. PMID:26501188

  11. Adaptive and active materials: selected papers from the ASME 2012 Conference on Smart Materials, Adaptive Structures and Intelligent Systems (SMASIS 12) (Stone Mountain, GA, USA, 19-21 September 2012)

    NASA Astrophysics Data System (ADS)

    Seelecke, Stefan; Erturk, Alper; Ounaies, Zoubeida; Naguib, Hani; Huber, John; Turner, Travis; Anderson, Iain; Philen, Michael; Baba Sundaresan, Vishnu

    2013-09-01

    The fifth annual meeting of the ASME/AIAA Smart Materials, Adaptive Structures and Intelligent Systems Conference (SMASIS) was held in beautiful Stone Mountain near Atlanta, GA. It is the conference's objective to provide an up-to-date overview of research trends in the entire field of smart materials systems. This was reflected in keynote speeches by Professor Eduard Arzt (Institute of New Materials and Saarland University, Saarbrücken, Germany) on 'Micro-patterned artificial 'Gecko' surfaces: a path to switchable adhesive function', by Professor Ray H Baughman (The Alan G MacDiarmid NanoTech Institute, University of Texas at Dallas) on 'The diverse and growing family of carbon nanotube and related artificial muscles', and by Professor Richard James (University of Minnesota) on 'The direct conversion of heat to electricity using multiferroic materials with phase transformations'. SMASIS 2012 was divided into eight symposia which span basic research, applied technological design and development, and industrial and governmental integrated system and application demonstrations. • SYMP 1. Development and characterization of multifunctional materials. • SYMP 2. Mechanics and behavior of active materials. • SYMP 3. Modeling, simulation and control of adaptive systems. • SYMP 4. Integrated system design and implementation. • SYMP 5. Structural health monitoring/NDE. • SYMP 6. Bio-inspired materials and systems. • SYMP 7. Energy harvesting. • SYMP 8. Structural and materials logic. This year we were particularly excited to introduce a new symposium on energy harvesting, which has quickly matured from a special track in previous years to an independent symposium for the first time. The subject cuts across fields by studying different materials, ranging from piezoelectrics to electroactive polymers, as well as by emphasizing different energy sources from wind to waves and ambient vibrations. Modeling, experimental studies, and technology applications all

  12. Flood-inundation maps for Peachtree Creek from the Norfolk Southern Railway bridge to the Moores Mill Road NW bridge, Atlanta, Georgia

    USGS Publications Warehouse

    Musser, Jonathan W.

    2012-01-01

    Digital flood-inundation maps for a 5.5-mile reach of the Peachtree Creek from the Norfolk Southern Railway bridge to the Moores Mill Road NW bridge, were developed by the U.S. Geological Survey (USGS) in cooperation with the City of Atlanta, Georgia. The inundation maps, which can be accessed through the USGS Flood Inundation Mapping Science Web site at http://water.usgs.gov/osw/flood_inundation/, depict estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at the USGS streamgage at Peachtree Creek at Atlanta, Georgia (02336300) and the USGS streamgage at Chattahoochee River at Georgia 280, near Atlanta, Georgia (02336490). Current water level (stage) at these USGS streamgages may be obtained at http://waterdata.usgs.gov/ and can be used in conjunction with these maps to estimate near real-time areas of inundation. The National Weather Service (NWS) is incorporating results from this study into the Advanced Hydrologic Prediction Service (AHPS) flood warning system (http:/water.weather.gov/ahps/). The NWS forecasts flood hydrographs at many places that commonly are collocated at USGS streamgages. The forecasted peak-stage information for the USGS streamgage at Peachtree Creek, which is available through the AHPS Web site, may be used in conjunction with the maps developed in this study to show predicted areas of flood inundation. A one-dimensional step-backwater model was developed using the U.S. Army Corps of Engineers HEC–RAS software for a 6.5-mile reach of Peachtree Creek and was used to compute flood profiles for a 5.5-mile reach of the creek. The model was calibrated using the most current stage-discharge relations at the Peachtree Creek at Atlanta, Georgia, streamgage (02336300), and the Chattahoochee River at Georgia 280, near Atlanta, Georgia, streamgage (02336490) as well as high water marks collected during the 2010 annual peak flow event. The hydraulic model was then used to determine 50 water

  13. Hot Meetings

    NASA Technical Reports Server (NTRS)

    Chiu, Mary

    2002-01-01

    A colleague walked by my office one time as I was conducting a meeting. There were about five or six members of my team present. The colleague, a man who had been with our institution (The Johns Hopkins Applied Physics Lab, a.k.a. APL) for many years, could not help eavesdropping. He said later it sounded like we we re having a raucous argument, and he wondered whether he should stand by the door in case things got out of hand and someone threw a punch. Our Advanced Composition Explorer (ACE) team was a hot group, to invoke the language that is fashionable today, although we never thought of ourselves in those terms. It was just our modus operandi. The tenor of the discussion got loud and volatile at times, but I prefer to think of it as animated, robust, or just plain collaborative. Mary Chiu and her "hot" team from the Johns Hopkins Applied Physics Laboratory built the Advanced Composition Explorer spacecraft for NASA. Instruments on the spacecraft continue to collect data that inform us about what's happening on our most important star, the Sun.

  14. Influence of internal electric fields on band gaps in short period GaN/GaAlN and InGaN/GaN polar superlattices

    SciTech Connect

    Gorczyca, I. Skrobas, K.; Suski, T.; Christensen, N. E.; Svane, A.

    2015-08-21

    The electronic structures of short period mGaN/nGa{sub y}Al{sub 1−y}N and mIn{sub y}Ga{sub 1-y}N/nGaN superlattices grown along the wurtzite c axis have been calculated for different alloy compositions y and various small numbers m of well- and n of barrier-monolayers. The general trends in gap behavior can, to a large extent, be related to the strength of the internal electric field, E, in the GaN and InGaN quantum wells. In the GaN/GaAlN superlattices, E reaches 4 MV/cm, while in the InGaN/GaN superlattices, values as high as E ≈ 6.5 MV/cm are found. The strong electric fields are caused by spontaneous and piezoelectric polarizations, the latter contribution dominating in InGaN/GaN superlattices. The influence of different arrangements of In atoms (indium clustering) on the band gap values in InGaN/GaN superlattices is examined.

  15. Third Year Continuation of a Research and Design Criteria for the Implementation and Establishment of a Neighborhood Information Center in Five Public Libraries: Atlanta, Cleveland, Detroit, Houston, and Queens Borough. Final Summary Report.

    ERIC Educational Resources Information Center

    Childers, Thomas

    The 1972-1975 Neighborhood Information Center (NIC) Project was undertaken in Atlanta, Cleveland, Detroit, Houston, and Queens Borough to demonstrate the feasibility of using existing library branches as neighborhood information centers. This summary evaluation utilized data from site visits, interviews with staff and clients, a questionnaire…

  16. Public Hearing: Report of the Proceedings of a Public Hearing of the Task Force on Women, Minorities and the Handicapped in Science and Technology (Atlanta, Georgia, March 2, 1988).

    ERIC Educational Resources Information Center

    Task Force on Women, Minorities, and the Handicapped in Science and Technology, Washington, DC.

    The Task Force on Women, Minorities, and the Handicapped in Science and Technology was established by the U.S. Congress in Public Law 99-383 with the purpose of developing a long-range plan for broadening participation in science and engineering. Public hearings were held in Albuquerque (New Mexico), Atlanta (Georgia), Baltimore (Maryland), Boston…

  17. Intense terahertz emission from molecular beam epitaxy-grown GaAs/GaSb(001)

    SciTech Connect

    Sadia, Cyril P.; Laganapan, Aleena Maria; Agatha Tumanguil, Mae; Estacio, Elmer; Somintac, Armando; Salvador, Arnel; Que, Christopher T.; Yamamoto, Kohji; Tani, Masahiko

    2012-12-15

    Intense terahertz (THz) electromagnetic wave emission was observed in undoped GaAs thin films deposited on (100) n-GaSb substrates via molecular beam epitaxy. GaAs/n-GaSb heterostructures were found to be viable THz sources having signal amplitude 75% that of bulk p-InAs. The GaAs films were grown by interruption method during the growth initiation and using various metamorphic buffer layers. Reciprocal space maps revealed that the GaAs epilayers are tensile relaxed. Defects at the i-GaAs/n-GaSb interface were confirmed by scanning electron microscope images. Band calculations were performed to infer the depletion region and electric field at the i-GaAs/n-GaSb and the air-GaAs interfaces. However, the resulting band calculations were found to be insufficient to explain the THz emission. The enhanced THz emission is currently attributed to a piezoelectric field induced by incoherent strain and defects.

  18. 75 FR 22100 - Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-27

    ... the Federal Register on April 13, 2010 (75 FR 18781). At the Board meeting scheduled on the afternoon... meetings and public hearing. Persons attending Board meetings are requested to refrain from using...

  19. 75 FR 80455 - Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-22

    ...; ] ARCHITECTURAL AND TRANSPORTATION BARRIERS COMPLIANCE BOARD Meetings AGENCY: Architectural and Transportation Barriers Compliance Board. ACTION: Notice of meetings. SUMMARY: The Architectural and Transportation Barriers Compliance Board (Access Board) plans to hold its regular committee and Board meetings...

  20. Effect of high density H 2 plasmas on InGaP/GaAs and AlGaAs/GaAs HEMTs

    NASA Astrophysics Data System (ADS)

    Ren, F.; Kopf, R. F.; Kuo, J. M.; Lothian, J. R.; Lee, J. W.; Pearton, S. J.; Shul, R. J.; Constantine, C.; Johnson, D.

    1998-05-01

    InGaP/GaAs and AlGaAs/GaAs high electron mobility transistors have been exposed to inductively coupled plasma or electron cyclotron resonance H 2 plasmas as a function of pressure, source power and rf chuck power. The transconductance, gate ideality factor and saturated drain-source current are all degraded by the plasma treatment. Two mechanisms are identified: passivation of Si dopants in the InGaP or AlGaAs donor layers by H 0 and lattice disorder created by H + and H 2+ ion bombardment. HEMTs are found to be more susceptible to plasma-induced degradation than heterojunction bipolar transistors.

  1. GaN as a radiation hard particle detector

    NASA Astrophysics Data System (ADS)

    Grant, J.; Bates, R.; Cunningham, W.; Blue, A.; Melone, J.; McEwan, F.; Vaitkus, J.; Gaubas, E.; O'Shea, V.

    2007-06-01

    Semiconductor tracking detectors at experiments such as ATLAS and LHCb at the CERN Large Hadron Collider (LHC) will be subjected to intense levels of radiation. The proposed machine upgrade, the Super-LHC (SLHC), to 10 times the initial luminosity of the LHC will require detectors that are ultra-radiation hard. Much of the current research into finding a detector that will meet the requirements of the SLHC has focused on using silicon substrates with enhanced levels of oxygen, for example Czochralski silicon and diffusion oxygenated float zone silicon, and into novel detector structures such as 3D devices. Another avenue currently being investigated is the use of wide band gap semiconductors such as silicon carbide (SiC) and gallium nitride (GaN). Both SiC and GaN should be intrinsically more radiation hard than silicon. Pad and guard ring structures were fabricated on three epitaxial GaN wafers. The epitaxial GaN thickness was either 2.5 or 12 μm and the fabricated detectors were irradiated to various fluences with 24 GeV/c protons and 1 MeV neutrons. Detectors were characterised pre- and post-irradiation by performing current-voltage ( I- V) and charge collection efficiency (CCE) measurements. Devices fabricated on 12 μm epitaxial GaN irradiated to fluences of 1016 protons cm-2 and 1016 neutrons cm-2 show maximum CCE values of 26% and 20%, respectively, compared to a maximum CCE of 53% of the unirradiated device.

  2. Exploiting Satellite Remote-Sensing Data in Fine Particulate Matter Characterization for Serving the Environmental Public Health Tracking Network (EPHTN): The HELIX-Atlanta Experience and NPOESS Implications

    NASA Technical Reports Server (NTRS)

    Al-Hamdan, Mohammad Z.; Crosson, William L.; Limaye, Ashutosh S.; Rickman, Douglas L.; Quattrochi, Dale A.; Estes, Maurice G.; Qualters, Judith R.; Sinclair, Amber H.; Tolsma, Dennis D.; Adeniyi, Kafayat A.

    2008-01-01

    As part of the U.S. National Environmental Public Health Tracking Network (EPHTN), the National Center for Environmental Health (NCEH) at the U.S. Centers for Disease Control and Prevention (CDC) led a project in collaboration with the National Aeronautics and Space Administration (NASA) Marshall Space Flight Center (MSFC) called Health and Environment Linked for Information Exchange (HELIX-Atlanta). Under HELIX-Atlanta, pilot projects were conducted to develop methods to better characterize exposure; link health and environmental datasets; and analyze spatial/temporal relationships. This paper describes and demonstrates different techniques for surfacing daily environmental hazards data of particulate matter with aerodynamic diameter less than or equal to 2.5 micrometers (PM(sub 2.5) for the purpose of integrating respiratory health and environmental data for the CDC's pilot study of HELIX-Atlanta. It describes a methodology for estimating ground-level continuous PM(sub 2.5) concentrations using spatial surfacing techniques and leveraging NASA Moderate Resolution Imaging Spectrometer (MODIS) data to complement the U.S. Environmental Protection Agency (EPA) ground observation data. The study used measurements of ambient PM(sub 2.5) from the EPA database for the year 2003 as well as PM(sub 2.5) estimates derived from NASA's MODIS data. Hazard data have been processed to derive the surrogate exposure PM(sub 2.5) estimates. The paper has shown that merging MODIS remote sensing data with surface observations of PM(sub 2.5), may provide a more complete daily representation of PM(sub 2.5), than either data set alone would allow, and can reduce the errors in the PM(sub 2.5) estimated surfaces. Future work in this area should focus on combining MODIS column measurements with profile information provided by satellites like the National Polar-orbiting Operational Environmental Satellite System (NPOESS). The Visible Infrared Imager/Radiometer Suite (VIIRS) and the Aerosol

  3. Piezoelectric Franz-Keldysh effect in a GaN/InGaN/AlGaN multilayer structure

    NASA Astrophysics Data System (ADS)

    Hou, Yong T.; Teo, Kie L.; Li, Ming Fu; Uchida, Kazuo; Tokunaga, Hiroki; Akutsu, Nakao; Matsumoto, Koh

    1999-11-01

    Contactless electroreflectance (CER) of a GaN/InGaN/AlGaN multilayer structure grown on sapphire has been measured in the temperature range of 15K and 450K. Except for the GaN exciton structures, well-defined Franz-Keldysh Oscillations are observed above the AlGaN band gap. An electomodulational model based on complex Airy functions is used to analyze the FKOs line shape. The temperature dependence of transition energies is obtained both for GaN and AlGaN. The magnitude of the built in electric field in AlGaN layer is also determined. The temperature dependence of the electric field is found to be consistent with the variation of thermal strain in the epilayer. It is demonstrated that the built-in electric field can be identified to be due to the piezoelectric effect.

  4. Band alignment of lattice-matched InGaPN/GaAs and GaAs/InGaPN quantum wells grown by MOVPE

    NASA Astrophysics Data System (ADS)

    Kaewket, Dares; Sanorpim, Sakuntam; Tungasmita, Sukkaneste; Katayama, Ryuji; Onabe, Kentaro

    2010-02-01

    The band alignment of nearly lattice-matched In 0.528Ga 0.472P 1- yN y/GaAs and GaAs/In 0.528Ga 0.472P 1- yN y quantum wells with N content of y=0.027 on GaAs (0 0 1) substrates grown by metalorganic vapor phase epitaxy were studied using low-temperature and temperature dependent photoluminescence (PL). Low temperature (10 K) PL shows the emission ( EPL,QW) in the infrared region which related to sample’s structures. For GaAs/In 0.528Ga 0.472P 0.973N 0.027 QW, the EPL,QW emission was observed at temperature up to 260 K. The results reveal that the In 0.528Ga 0.472P 0.973N 0.027/GaAs and GaAs/In 0.528Ga 0.472P 0.973N 0.027 quantum wells exhibit a type-II quantum structure. Valence band offset Δ EV as large as 450 meV was estimated for GaAs/In 0.528Ga 0.472P 0.973N 0.027 quantum well while the conduction band offset Δ EC was estimated to be 160 meV for In 0.528Ga 0.472P 0.973N 0.027/GaAs quantum well. This type-II quantum structures refer to the natural type-II band alignment between In xGa 1- xP 1- yN y ( x=0.528, y=0.027) and GaAs, which is useful for separation electrons and holes in the electronic and photovoltaic applications.

  5. Study of GaP single crystal layers grown on GaN by MOCVD

    SciTech Connect

    Li, Shuti; Liu, Chao; Ye, Guoguang; Xiao, Guowei; Zhou, Yugang; Su, Jun; Fan, Guanghan; Zhang, Yong; Liang, Fubo; Zheng, Shuwen

    2011-11-15

    Highlights: {yields} We investigated the growth of GaP layers on GaN by MOCVD. {yields} A single crystal GaP layer could be grown on GaN. {yields} The V/III ratio played an important role to improve GaP layer quality. {yields} The GaP:Mg layer with hole concentration of 4.2 x 10{sup 18} cm{sup -3} was obtained. -- Abstract: The performance of GaN based devices could possibly be improved by utilizing the good p-type properties of GaP layer and it provides the possibility of the integration of InAlGaN and AlGaInP materials to produce new devices, if high quality GaP compounds can be grown on III-nitride compounds. In this paper, the growth of GaP layers on GaN by metalorganic chemical vapor deposition (MOCVD) has been investigated. The results show that the GaP low temperature buffer layer can provide a high density of nucleation sites for high temperature GaP growth. Using a 40 nm thick GaP buffer layer, a single crystal GaP layer, whose full-width at half-maximum of the (1 1 1) plane measured by double crystal X-ray diffraction is 580'', can be grown on GaN. The V/III ratio plays an important role in the GaP layer growth and an appropriate V/III ratio can improve the quality of GaP layer. The GaP:Mg layer with hole carrier concentration of 4.2 x 10{sup 18} cm{sup -3} has been obtained.

  6. New GaInP/GaAs/GaInAs, Triple-Bandgap, Tandem Solar Cell for High-Efficiency Terrestrial Concentrator Systems

    SciTech Connect

    Kurtz, S.; Wanlass, M.; Kramer, C.; Young, M.; Geisz, J.; Ward, S.; Duda, A.; Moriarty, T.; Carapella, J.; Ahrenkiel, P.; Emery. K.; Jones, K.; Romero, M.; Kibbler, A.; Olson, J.; Friedman, D.; McMahon, W.; Ptak, A.

    2005-11-01

    GaInP/GaAs/GaInAs three-junction cells are grown in an inverted configuration on GaAs, allowing high quality growth of the lattice matched GaInP and GaAs layers before a grade is used for the 1-eV GaInAs layer. Using this approach an efficiency of 37.9% was demonstrated.

  7. 46 CFR 7.80 - Tybee Island, GA to St. Simons Island, GA.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Tybee Island, GA to St. Simons Island, GA. 7.80 Section... BOUNDARY LINES Atlantic Coast § 7.80 Tybee Island, GA to St. Simons Island, GA. (a) A line drawn from the southernmost extremity of Savannah Beach on Tybee Island 255° true across Tybee Inlet to the shore of...

  8. 46 CFR 7.80 - Tybee Island, GA to St. Simons Island, GA.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Tybee Island, GA to St. Simons Island, GA. 7.80 Section... BOUNDARY LINES Atlantic Coast § 7.80 Tybee Island, GA to St. Simons Island, GA. (a) A line drawn from the southernmost extremity of Savannah Beach on Tybee Island 255° true across Tybee Inlet to the shore of...

  9. 46 CFR 7.80 - Tybee Island, GA to St. Simons Island, GA.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Tybee Island, GA to St. Simons Island, GA. 7.80 Section... BOUNDARY LINES Atlantic Coast § 7.80 Tybee Island, GA to St. Simons Island, GA. (a) A line drawn from the southernmost extremity of Savannah Beach on Tybee Island 255° true across Tybee Inlet to the shore of...

  10. 46 CFR 7.80 - Tybee Island, GA to St. Simons Island, GA.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Tybee Island, GA to St. Simons Island, GA. 7.80 Section... BOUNDARY LINES Atlantic Coast § 7.80 Tybee Island, GA to St. Simons Island, GA. (a) A line drawn from the southernmost extremity of Savannah Beach on Tybee Island 255° true across Tybee Inlet to the shore of...

  11. 46 CFR 7.80 - Tybee Island, GA to St. Simons Island, GA.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Tybee Island, GA to St. Simons Island, GA. 7.80 Section... BOUNDARY LINES Atlantic Coast § 7.80 Tybee Island, GA to St. Simons Island, GA. (a) A line drawn from the southernmost extremity of Savannah Beach on Tybee Island 255° true across Tybee Inlet to the shore of...

  12. Native point defects in GaSb

    SciTech Connect

    Kujala, J.; Segercrantz, N.; Tuomisto, F.; Slotte, J.

    2014-10-14

    We have applied positron annihilation spectroscopy to study native point defects in Te-doped n-type and nominally undoped p-type GaSb single crystals. The results show that the dominant vacancy defect trapping positrons in bulk GaSb is the gallium monovacancy. The temperature dependence of the average positron lifetime in both p- and n-type GaSb indicates that negative ion type defects with no associated open volume compete with the Ga vacancies. Based on comparison with theoretical predictions, these negative ions are identified as Ga antisites. The concentrations of these negatively charged defects exceed the Ga vacancy concentrations nearly by an order of magnitude. We conclude that the Ga antisite is the native defect responsible for p-type conductivity in GaSb single crystals.

  13. Thirty-five years after Stonewall: an exploratory study of satisfaction with police among gay, lesbian, and bisexual persons at the 34th Annual Atlanta Pride Festival.

    PubMed

    Gillespie, Wayne

    2008-01-01

    The gay rights movement began in the summer of 1969 when gay men rioted against police for raiding a bar known as the Stonewall Inn. In the succeeding 35 years, very little research has explored the relationship between police organizations and gay, lesbian, bisexual, and transgendered (GLBT) communities. The purpose of this study is to describe the attitudes that GLBT persons currently hold toward police. Subjects were sampled from the 34th Annual Atlanta Pride Festival and asked to complete a self-administered questionnaire. Of the 179 GLBT participants, the vast majority reported high satisfaction with community policing practices at this event. Moreover, age, household income, victimization, security presence, and identification with gay-themed media significantly predicted attitudes toward police.

  14. Remote Sensing and Spatial Growth Modeling Coupled With Air Quality Modeling to Assess the Impact of Atlanta, Georgia on the Local and Regional Environment

    NASA Astrophysics Data System (ADS)

    Quattrochi, D. A.; Estes, M. G.; Crosson, W. L.; Johnson, H.; Khan, M.

    2006-05-01

    The growth of cities, both in population and areal extent, appears as an inexorable process. Urbanization continues at a rapid rate, and it is estimated that by the year 2025, 60 percent of the world's population will live in cities. Urban expansion has profound impacts on a host of biophysical, environmental, and atmospheric processes within an urban ecosystems perspective. A reduction in air quality over cities is a major result of these impacts. Because of its complexity, the urban landscape is not adequately captured in air quality models such as the Community Multiscale Air Quality (CMAQ) model that is used to assess whether urban areas are in attainment of EPA air quality standards, primarily for ground level ozone. This inadequacy of the CMAQ model to sufficiently respond to the heterogeneous nature of the urban landscape can impact how well the model predicts ozone levels over metropolitan areas and ultimately, whether cities exceed EPA ozone air quality standards. We are exploring the utility of high-resolution remote sensing data and urban spatial growth modeling (SGM) projections as improved inputs to a meteorological/air quality modeling system focusing on the Atlanta, Georgia metropolitan area as a case study. These growth projections include "business as usual" and "smart growth" scenarios out to 2030. The growth projections illustrate the effects of employing urban heat island mitigation strategies, such as increasing tree canopy and albedo across the Atlanta metro area, which in turn, are used to model how air temperature can potentially be moderated as impacts on elevating ground-level ozone, as opposed to not utilizing heat island mitigation strategies. The National Land Cover Dataset at 30m resolution is being used as the land use/land cover input and aggregated to the 4km scale for the MM5 mesoscale meteorological model and the CMAQ modeling schemes. Use of these data has been found to better characterize low density/suburban development as

  15. Spatial Growth Modeling and High Resolution Remote Sensing Data Coupled with Air Quality Modeling to Assess the Impact of Atlanta, Georgia on the Local and Regional Environment

    NASA Technical Reports Server (NTRS)

    Quattrochi, Dale A.; Estes, Maurice G., Jr.; Crosson, William; Johnson, Hoyt; Khan, Maudood

    2006-01-01

    The growth of cities, both in population and areal extent, appears as an inexorable process. Urbanization continues at a rapid rate, and it is estimated that by the year 2025, 60 percent of the world s population will live in cities. Urban expansion has profound impacts on a host of biophysical, environmental, and atmospheric processes within an urban ecosystems perspective. A reduction in air quality over cities is a major result of these impacts. Because of its complexity, the urban landscape is not adequately captured in air quality models such as the Community Multiscale Air Quality (CMAQ) model that is used to assess whether urban areas are in attainment of EPA air quality standards, primarily for ground level ozone. This inadequacy of the CMAQ model to sufficiently respond to the heterogeneous nature of the urban landscape can impact how well the model predicts ozone levels over metropolitan areas and ultimately, whether cities exceed EPA ozone air quality standards. We are exploring the utility of high-resolution remote sensing data and urban spatial growth modeling (SGM) projections as improved inputs to a meteorological/air quality modeling system focusing on the Atlanta, Georgia metropolitan area as a case study. These growth projections include business as usual and smart growth scenarios out to 2030. The growth projections illustrate the effects of employing urban heat island mitigation strategies, such as increasing tree canopy and albedo across the Atlanta metro area, which in turn, are used to model how air temperature can potentially be moderated as impacts on elevating ground-level ozone, as opposed to not utilizing heat island mitigation strategies. The National Land Cover Dataset at 30m resolution is being used as the land use/land cover input and aggregated to the 4km scale for the MM5 mesoscale meteorological model and the CMAQ modeling schemes. Use of these data has been found to better characterize low density/suburban development as compared

  16. Remote Sensing and Spatial Growth Modeling Coupled with Air Quality Modeling to Assess the Impact of Atlanta, Georgia on the Local and Regional Environment

    NASA Technical Reports Server (NTRS)

    Quattrochi, Dale A.; Estes, Maurice G., Jr.; Crosson, William; Khan, Maudood

    2006-01-01

    The growth of cities, both in population and areal extent, appears as an inexorable process. Urbanization continues at a rapid rate, and it is estimated that by the year 2025, 80 percent of the world s population will live in cities. Directly aligned with the expansion of cities is urban sprawl. Urban expansion has profound impacts on a host of biophysical, environmental, and atmospheric processes. A reduction in air quality over cities is a major result of these impacts. Strategies that can be directly or indirectly implemented to help remediate air quality problems in cities and that can be accepted by political decision makers and the general public are now being explored to help bring down air pollutants and improve air quality. The urban landscape is inherently complex and this complexity is not adequately captured in air quality models, particularly the Community Multiscale Air Quality (CMAQ) model that is used to assess whether urban areas are in attainment of EPA air quality standards, primarily for ground level ozone. This inadequacy of the CMAQ model to sufficiently respond to the heterogeneous nature of the urban landscape can impact how well the model predicts ozone pollutant levels over metropolitan areas and ultimately, whether cities exceed EPA ozone air quality standards. We are exploring the utility of high-resolution remote sensing data and urban spatial growth modeling (SGM) projections as improved inputs to the meteorology component of the CMAQ model focusing on the Atlanta, Georgia metropolitan area as a case study. These growth projections include "business as usual" and "smart growth" scenarios out to 2030. The growth projections illustrate the effects of employing urban heat island mitigation strategies, such as increasing tree canopy and albedo across the Atlanta metro area, which in turn, are used to model how ozone and air temperature can potentially be moderated as impacts on elevating ground-level ozone, as opposed to not utilizing heat

  17. Thirty-five years after Stonewall: an exploratory study of satisfaction with police among gay, lesbian, and bisexual persons at the 34th Annual Atlanta Pride Festival.

    PubMed

    Gillespie, Wayne

    2008-01-01

    The gay rights movement began in the summer of 1969 when gay men rioted against police for raiding a bar known as the Stonewall Inn. In the succeeding 35 years, very little research has explored the relationship between police organizations and gay, lesbian, bisexual, and transgendered (GLBT) communities. The purpose of this study is to describe the attitudes that GLBT persons currently hold toward police. Subjects were sampled from the 34th Annual Atlanta Pride Festival and asked to complete a self-administered questionnaire. Of the 179 GLBT participants, the vast majority reported high satisfaction with community policing practices at this event. Moreover, age, household income, victimization, security presence, and identification with gay-themed media significantly predicted attitudes toward police. PMID:19064482

  18. The National Conference on Professional and Personal Renewal for Faculty (2nd, Atlanta, Georgia, April 13-15, 1989).

    ERIC Educational Resources Information Center

    Georgia Univ., Athens. Office of Instructional Development.

    This document reports on the second of a projected series of conferences, for University of Georgia faculty, having the theme of "faculty renewal" (rather than the older "faculty development") as the major focus. Following a brief introduction, the proceedings open with the keynote speech, "Meeting the Challenge of Personal and Professional…

  19. Maternal age specific risk rate estimates for Down syndrome among live births in whites and other races from Ohio and metropolitan Atlanta, 1970-1989.

    PubMed Central

    Huether, C A; Ivanovich, J; Goodwin, B S; Krivchenia, E L; Hertzberg, V S; Edmonds, L D; May, D S; Priest, J H

    1998-01-01

    Our primary objective was to estimate, by one year and five year intervals, maternal age specific risk rates for Down syndrome among whites and among other races from two different populations, metropolitan Atlanta and south west Ohio, using live birth and prenatally diagnosed cases ascertained during 1970-1989. The five year estimates were also calculated separately for each of the five four year periods during these 20 years. Additionally, we compared two different methods of estimating these risk rates by using a third population of whites, and compared two different statistical methods of smoothing the risk rates. The results indicate good agreement between the metropolitan Atlanta and south west Ohio estimates within races, but show a statistically significant difference between the two race categories. Because 86% of live births in the "other races" category in the combined population are to blacks, these data may be seen as the first estimates of maternal age specific risk rates for Down syndrome among blacks calculated by one year intervals. We found excellent agreement in the risk rate estimates among the five four year time periods, between the estimates obtained by using the two different methods of estimation, and between the estimates obtained using the two different methods of statistical smoothing. Our estimated risk rates for white women in their 20s strongly reinforce those from previous studies currently being used for genetic counselling purposes. While we did find somewhat higher rates for women under 20, and increasingly higher rates for those over 30 years of age, these differences are not substantial. Thus, this study in general supports the risk rates estimated from data collected mostly during the 1960s and 1970s. PMID:9643290

  20. Perceived stress following race-based discrimination at work is associated with hypertension in African-Americans. The metro Atlanta heart disease study, 1999-2001.

    PubMed

    Din-Dzietham, Rebecca; Nembhard, Wendy N; Collins, Rakale; Davis, Sharon K

    2004-02-01

    There is increasing evidence of an association between stress related to job strain and hypertension. However little data exist on stress from racism and race-based discrimination at work (RBDW). The objective of this study was to investigate whether blood pressure (BP) outcomes are positively associated with stressful racism towards African-Americans from non-African-Americans as well as RBDW from other African-Americans. The metro Atlanta heart disease study was a population-based study which included 356 African-American men and women, aged >/=21 years, residing in metropolitan Atlanta, Georgia during 1999-2001. Perceived stress was self-reported by 197 participants for racism from non-African-Americans and 95 for RBDW from other African-Americans. Sitting systolic (SBP) and diastolic (DBP) BP were taken at a clinic visit and was the average of the last two of three BP measures. Hypertension was self-reported as physician-diagnosed high BP on 2 or more visits. Logistic and least-squares linear regression models were fit accordingly and separately for each type of stress, adjusting for age, gender, body mass index, and coping abilities. The likelihood of hypertension significantly increased with higher levels of perceived stress following racism from non-African-Americans, but not from RBDW from other African-Americans; adjusted odd ratios (95% CI) were 1.4 (1.0, 1.9) and 1.2 (0.8, 1.5) per unit increment of stress. The adjusted magnitude of SBP and DBP increase between low and very high level of stress, conversely, was greater when RBDW originated from African-Americans than racism from non-African-Americans. Stressful racism and RBDW encounters are associated with increased SBP and DBP and increased likelihood of hypertension in African-Americans. Future studies with a larger sample size are warranted to further explore these findings for mechanistic understanding and occupational policy consideration regarding stress risk reduction.

  1. Dead-space corrected GaInP/GaAs composite collector double heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    Poh, Z. S.; Yow, H. K.; Ong, D. S.; Houston, P. A.; Krysa, A. B.

    2007-04-01

    GaInP/GaAs/GaInP double heterojunction bipolar transistors incorporating dead-space corrected composite collectors were investigated experimentally. The optimized DHBT with a 10-nm lowly doped GaAs spacer and a 5-nm highly doped GaInP spacer has extended the operating range of the collector-emitter voltage, VCE, by maximizing the collector-emitter voltage at the onset of the multiplication, VCE ,onset, to 20 V, while minimizing the saturation voltage, VCE ,sat (<1 V), and maintaining the nominal breakdown voltage, BVCEO, of the GaInP collector at 25 V. The design incorporating an Al0.11Ga0.89As spacer rather than a GaInP spacer within the lowly doped GaAs-GaInP composite collector demonstrated similar breakdown behavior.

  2. Gold-free GaAs/GaAsSb heterostructure nanowires grown on silicon

    SciTech Connect

    Plissard, S.; Wallart, X.; Caroff, P.; Dick, K. A.

    2010-03-22

    Growth of GaAs/GaAsSb heterostructure nanowires on silicon without the need for gold seed particles is presented. A high vertical yield of GaAs nanowires is first obtained, and then GaAs{sub x}Sb{sub 1-x} segments are successfully grown axially in these nanowires. GaAsSb can also be integrated as a shell around the GaAs core. Finally, two GaAsSb segments are grown inside a GaAs nanowire and passivated using an Al{sub x}Ga{sub 1-x}As shell. It is found that no stacking faults or twin planes occur in the GaAsSb segments.

  3. Call a Meeting!

    ERIC Educational Resources Information Center

    Gonsalves, Bronte B.

    1988-01-01

    Outlines appropriate content for meetings between parents and teachers of young children. Argues that effective meetings foster parent education, communication and ongoing parent support. Identifies objectives for the initial meeting during the application and registration process, for parent education meetings, and for parent conferences.…

  4. Utilisation of GaN and InGaN/GaN with nanoporous structures for water splitting

    SciTech Connect

    Benton, J.; Bai, J.; Wang, T.

    2014-12-01

    We report a cost-effective approach to the fabrication of GaN based nanoporous structure for applications in renewable hydrogen production. Photoelectrochemical etching in a KOH solution has been employed to fabricate both GaN and InGaN/GaN nanoporous structures with pore sizes ranging from 25 to 60 nm, obtained by controlling both etchant concentration and applied voltage. Compared to as-grown planar devices the nanoporous structures have exhibited a significant increase of photocurrent with a factor of up to four times. An incident photon conversion efficiency of up to 46% around the band edge of GaN has been achieved.

  5. Placement of the GaBP ring system in the banded gastric bypass operation.

    PubMed

    Fobi, Mathias A L

    2005-09-01

    Currently, bariatric surgeons fashion the band or ring reinforcement prosthesis, to control the stoma in the vertical banded gastroplasty and gastric bypass operations for morbid obesity. To meet this need, the GaBP Ring system has been developed in various sizes, and consists of 4 main parts to provide a means for inserting a ring around the gastric pouch in the banded gastric bypass or the vertical banded gastroplasty. The pre-manufactured and sterilized device provides for better standardization and quality control than individually surgeon-fashioned devices. The GaBP Ring system is described, and the technique of placement and the pertinent initial clinical results are presented. PMID:16197796

  6. Polarization-induced Zener tunnel diodes in GaN/InGaN/GaN heterojunctions

    SciTech Connect

    Yan, Xiaodong; Li, Wenjun; Islam, S. M.; Pourang, Kasra; Fay, Patrick; Xing, Huili; Jena, Debdeep

    2015-10-19

    By the insertion of thin In{sub x}Ga{sub 1−x}N layers into Nitrogen-polar GaN p-n junctions, polarization-induced Zener tunnel junctions are studied. The reverse-bias interband Zener tunneling current is found to be weakly temperature dependent, as opposed to the strongly temperature-dependent forward bias current. This indicates tunneling as the primary reverse-bias current transport mechanism. The Indium composition in the InGaN layer is systematically varied to demonstrate the increase in the interband tunneling current. Comparing the experimentally measured tunneling currents to a model helps identify the specific challenges in potentially taking such junctions towards nitride-based polarization-induced tunneling field-effect transistors.

  7. Temperature coefficients for GaInP/GaAs/GaInNAsSb solar cells

    SciTech Connect

    Aho, Arto; Isoaho, Riku; Tukiainen, Antti; Polojärvi, Ville; Aho, Timo; Raappana, Marianna; Guina, Mircea

    2015-09-28

    We report the temperature coefficients for MBE-grown GaInP/GaAs/GaInNAsSb multijunction solar cells and the corresponding single junction sub-cells. Temperature-dependent current-voltage measurements were carried out using a solar simulator equipped with a 1000 W Xenon lamp and a three-band AM1.5D simulator. The triple-junction cell exhibited an efficiency of 31% at AM1.5G illumination and an efficiency of 37–39% at 70x real sun concentration. The external quantum efficiency was also measured at different temperatures. The temperature coefficients up to 80°C, for the open circuit voltage, the short circuit current density, and the conversion efficiency were determined to be −7.5 mV/°C, 0.040 mA/cm{sup 2}/°C, and −0.09%/°C, respectively.

  8. Effect of buffer structures on AlGaN/GaN high electron mobility transistor reliability

    SciTech Connect

    Liu, L.; Xi, Y. Y.; Ren, F.; Pearton, S. J.; Laboutin, O.; Cao, Yu; Johnson, Wayne J.; Kravchenko, Ivan I

    2012-01-01

    AlGaN/GaN high electron mobility transistors (HEMTs) with three different types of buffer layers, including a GaN/AlGaN composite layer, or 1 or 2 lm GaN thick layers, were fabricated and their reliability compared. The HEMTs with the thick GaN buffer layer showed the lowest critical voltage (Vcri) during off-state drain step-stress, but this was increased by around 50% and 100% for devices with the composite AlGaN/GaN buffer layers or thinner GaN buffers, respectively. The Voff - state for HEMTs with thin GaN and composite buffers were 100 V, however, this degraded to 50 60V for devices with thick GaN buffers due to the difference in peak electric field near the gate edge. A similar trend was observed in the isolation breakdown voltage measurements, with the highest Viso achieved based on thin GaN or composite buffer designs (600 700 V), while a much smaller Viso of 200V was measured on HEMTs with the thick GaN buffer layers. These results demonstrate the strong influence of buffer structure and defect density on AlGaN/GaN HEMT performance and reliability.

  9. NASA In-Space Propulsion Technologies and Their Infusion Potential

    NASA Technical Reports Server (NTRS)

    Pencil, Eric J.; Anderson, David

    2013-01-01

    This is an overview presentation of In Space Propulsion Technology products that have been developed under the sponsorship of the Planetary Science Division of NASA's Science Mission Directorate. The materials have been prepared for Outer Planetary Assessment Group Meeting in Atlanta, GA in January 2013.

  10. 86th Annual Georgia Public Health Association Meeting & Conference Report

    PubMed Central

    Smith, Selina A.; Abbott, Regina; Sims, Christy

    2015-01-01

    EXECUTIVE SUMMARY The 86th annual meeting of the Georgia Public Health Association (GPHA) and joint conference with the Southern Health Association was held in Atlanta, Georgia, on April 13–14, 2015, with pre-conference (April 12th) and post-conference (April 14th) Executive Board meetings. As Georgia’s leading forum for public health researchers, practitioners, and students, the annual meeting of the GPHA brings together participants from across the state to explore recent developments in the field and to exchange techniques, tools, and experiences. Historically, the GPHA conference has been held in Savannah (n=24); Jekyll Island (n=20); Atlanta (n=16); Augusta (n=4); and Gainesville (n=1). There was no annual meeting during the early years (1929–1936); during World War II (1941–1943 and 1945); and for four years during the 1980s. Between 2006 and 2010, GPHA held one-day annual meetings and business sessions with educational workshops. Several new initiatives were highlighted as part of this year’s conference. These included a “move and groove” physical activity lounge, registration scholarships for students with a dedicated meet-and-greet reception, an expanded exhibit hall, presentation and approval of three resolutions (related to healthy foods at official activities and events; weapons at official activities and events; and memorials), and approval of the 2015 legislative policy positions and amended association bylaws. The theme for the conference was Advocacy in Action for Public Health. Specifically, the program addressed ensuring access to care; protecting funding for core programs, services, and infrastructure; eliminating health disparities; and addressing key public health issues important to the state of Georgia. One hundred and nine (109) abstracts were submitted for peer review; 36 were accepted for poster and 40 for workshop presentations. Four plenary sessions with keynote speakers covered the intersection between advocacy and policy

  11. Photoelectron spectroscopy of GaX2-, Ga2X-, Ga2X2-, and Ga2X3-(X=P,As)

    NASA Astrophysics Data System (ADS)

    Taylor, Travis R.; Gómez, Harry; Asmis, Knut R.; Neumark, Daniel M.

    2001-09-01

    Anion photoelectron spectra taken at various photodetachment wavelengths have been obtained for GaX2-, Ga2X-, Ga2X2-, and Ga2X3- (X=P,As). The incorporation of a liquid nitrogen cooled channel in the ion source resulted in substantial vibrational cooling of the cluster anions, resulting in resolved vibrational progressions in the photoelectron spectra of all species except Ga2X2-. Electron affinities, electronic term values, and vibrational frequencies are reported and compared to electronic structure calculations. In addition, similarities and differences between the phosphorus and arsenic-containing isovalent species are discussed.

  12. Coulomb excitation of Ga73

    NASA Astrophysics Data System (ADS)

    Diriken, J.; Stefanescu, I.; Balabanski, D.; Blasi, N.; Blazhev, A.; Bree, N.; Cederkäll, J.; Cocolios, T. E.; Davinson, T.; Eberth, J.; Ekström, A.; Fedorov, D. V.; Fedosseev, V. N.; Fraile, L. M.; Franchoo, S.; Georgiev, G.; Gladnishki, K.; Huyse, M.; Ivanov, O. V.; Ivanov, V. S.; Iwanicki, J.; Jolie, J.; Konstantinopoulos, T.; Kröll, Th.; Krücken, R.; Köster, U.; Lagoyannis, A.; Lo Bianco, G.; Maierbeck, P.; Marsh, B. A.; Napiorkowski, P.; Patronis, N.; Pauwels, D.; Reiter, P.; Seliverstov, M.; Sletten, G.; van de Walle, J.; van Duppen, P.; Voulot, D.; Walters, W. B.; Warr, N.; Wenander, F.; Wrzosek, K.

    2010-12-01

    The B(E2;Ii→If) values for transitions in 3171Ga40 and 3173Ga42 were deduced from a Coulomb excitation experiment at the safe energy of 2.95 MeV/nucleon using post-accelerated beams of Ga71,73 at the REX-ISOLDE on-line isotope mass separator facility. The emitted γ rays were detected by the MINIBALL γ-detector array, and B(E2;Ii→If) values were obtained from the yields normalized to the known strength of the 2+→0+ transition in the Sn120 target. The comparison of these new results with the data of less neutron-rich gallium isotopes shows a shift of the E2 collectivity toward lower excitation energy when adding neutrons beyond N=40. This supports conclusions from previous studies of the gallium isotopes, which indicated a structural change in this isotopic chain between N=40 and 42. Combined with recent measurements from collinear laser spectroscopy showing a 1/2- spin and parity for the ground state, the extracted results revealed evidence for a 1/2-,3/2- doublet near the ground state in 3173Ga42 differing by at most 0.8 keV in energy.

  13. Reliability, failure modes, and degradation mechanisms in high power single- and multi-mode InGaAs-AlGaAs strained quantum well lasers

    NASA Astrophysics Data System (ADS)

    Sin, Yongkun; Presser, Nathan; Lingley, Zachary; Brodie, Miles; Foran, Brendan; Moss, Steven C.

    2016-03-01

    High power single-mode (SM) and multi-mode (MM) InGaAs-AlGaAs strained quantum well (QW) lasers are critical components for both telecommunications and potential space satellite communications systems. However, little has been reported on failure modes of state-of-the-art SM InGaAs-AlGaAs strained QW lasers although it is crucial to understand failure modes and underlying degradation mechanisms in developing these lasers that meet lifetime requirements for space satellite systems, where extremely high reliability of these lasers is required. Our present study addresses the aforementioned issues by performing long-term life tests under different test conditions followed by failure mode analysis (FMA) and physics of failure investigation. We performed long-term accelerated life-tests on state-of-the-art SM and MM InGaAs-AlGaAs strained QW lasers under ACC (automatic current control) mode. Our life-tests have accumulated over 25,000 test hours for SM lasers and over 35,000 test hours for MM lasers. FMA was performed on failed SM lasers using electron beam induced current (EBIC). This technique allowed us to identify failure types by observing dark line defects. All the SM failures we studied showed catastrophic and sudden degradation and all of these failures were bulk failures. Our group previously reported that bulk failure or COBD (catastrophic optical bulk damage) is the dominant failure mode of MM InGaAs-AlGaAs strained QW lasers. To the best of our knowledge, this is the first report demonstrating that the dominant failure mode of both SM and MM InGaAs-AlGaAs strained QW lasers is the bulk failure. Since degradation mechanisms responsible for COBD are still not well understood, we also employed other techniques including focused ion beam (FIB) processing and high-resolution TEM to further study dark line defects and dislocations in post-aged SM and MM lasers. Our long-term life test results and FMA results are reported.

  14. Green light emission by InGaN/GaN multiple-quantum-well microdisks

    SciTech Connect

    Hsu, Yu-Chi; Lo, Ikai Shih, Cheng-Hung; Pang, Wen-Yuan; Hu, Chia-Hsuan; Wang, Ying-Chieh; Tsai, Cheng-Da; Chou, Mitch M. C.; Hsu, Gary Z. L.

    2014-03-10

    The high-quality In{sub x}Ga{sub 1−x}N/GaN multiple quantum wells were grown on GaN microdisks with γ-LiAlO{sub 2} substrate by using low-temperature two-step technique of plasma-assisted molecular beam epitaxy. We demonstrated that the hexagonal GaN microdisk can be used as a strain-free substrate to grow the advanced In{sub x}Ga{sub 1−x}N/GaN quantum wells for the optoelectronic applications. We showed that the green light of 566-nm wavelength (2.192 eV) emitted from the In{sub x}Ga{sub 1−x}N/GaN quantum wells was tremendously enhanced in an order of amplitude higher than the UV light of 367-nm wavelength (3.383 eV) from GaN.

  15. Computational Chemistry Study on Crystal Growth of InGaN/GaN

    NASA Astrophysics Data System (ADS)

    Inaba, Yusaku; Onozu, Takayuki; Takami, Seiichi; Kubo, Momoji; Miyamoto, Akira; Imamura, Akira

    2001-04-01

    We carried out density functional theory (DFT) calculations and tight-binding quantum chemical molecular dynamics simulations to investigate the crystal growth of InGaN layers on a GaN(0001) surface under periodic boundary conditions. The periodic DFT calculations indicate that the formation of the uniform InGaN thin films is difficult, which leads to the segregation of In atoms in the InGaN thin films. The tight-binding quantum chemical molecular dynamics simulations suggest that the Ga polarity surface of the GaN(0001) is preferable for the construction of the smooth GaN thin films than the N polarity surface of the GaN(0001). Moreover, the formation of the smooth InN thin films was found to be difficult on the GaN(0001) surface.

  16. Titanium induced polarity inversion in ordered (In,Ga)N/GaN nanocolumns

    NASA Astrophysics Data System (ADS)

    Kong, X.; Li, H.; Albert, S.; Bengoechea-Encabo, A.; Sanchez-Garcia, M. A.; Calleja, E.; Draxl, C.; Trampert, A.

    2016-02-01

    We report on the formation of polarity inversion in ordered (In,Ga)N/GaN nanocolumns grown on a Ti-masked GaN-buffered sapphire substrate by plasma assisted molecular beam epitaxy. High-resolution transmission electron microscopy and electron energy-loss spectroscopy reveal a stacking fault-like planar defect at the homoepitaxial GaN interface due to Ti incorporation, triggering the generation of N-polar domains in Ga-polar nanocolumns. Density functional theory calculations are applied to clarify the atomic configurations of a Ti monolayer occupation on the GaN (0002) plane and to prove the inversion effect. The polarity inversion leads to an enhanced indium incorporation in the subsequent (In,Ga)N segment of the nanocolumn. This study provides a deeper understanding of the effects of Ti mask in the well-controlled selective area growth of (In,Ga)N/GaN nanocolumns.

  17. Titanium induced polarity inversion in ordered (In,Ga)N/GaN nanocolumns.

    PubMed

    Kong, X; Li, H; Albert, S; Bengoechea-Encabo, A; Sanchez-Garcia, M A; Calleja, E; Draxl, C; Trampert, A

    2016-02-12

    We report on the formation of polarity inversion in ordered (In,Ga)N/GaN nanocolumns grown on a Ti-masked GaN-buffered sapphire substrate by plasma assisted molecular beam epitaxy. High-resolution transmission electron microscopy and electron energy-loss spectroscopy reveal a stacking fault-like planar defect at the homoepitaxial GaN interface due to Ti incorporation, triggering the generation of N-polar domains in Ga-polar nanocolumns. Density functional theory calculations are applied to clarify the atomic configurations of a Ti monolayer occupation on the GaN (0002) plane and to prove the inversion effect. The polarity inversion leads to an enhanced indium incorporation in the subsequent (In,Ga)N segment of the nanocolumn. This study provides a deeper understanding of the effects of Ti mask in the well-controlled selective area growth of (In,Ga)N/GaN nanocolumns.

  18. InGaAsN/GaAs heterojunction for multi-junction solar cells

    DOEpatents

    Kurtz, Steven R.; Allerman, Andrew A.; Klem, John F.; Jones, Eric D.

    2001-01-01

    An InGaAsN/GaAs semiconductor p-n heterojunction is disclosed for use in forming a 0.95-1.2 eV bandgap photodetector with application for use in high-efficiency multi-junction solar cells. The InGaAsN/GaAs p-n heterojunction is formed by epitaxially growing on a gallium arsenide (GaAs) or germanium (Ge) substrate an n-type indium gallium arsenide nitride (InGaAsN) layer having a semiconductor alloy composition In.sub.x Ga.sub.1-x As.sub.1-y N.sub.y with 0GaAs layer, with the InGaAsN and GaAs layers being lattice-matched to the substrate. The InGaAsN/GaAs p-n heterojunction can be epitaxially grown by either molecular beam epitaxy (MBE) or metalorganic chemical vapor deposition (MOCVD). The InGaAsN/GaAs p-n heterojunction provides a high open-circuit voltage of up to 0.62 volts and an internal quantum efficiency of >70%.

  19. MOVPE of GaSb/InGaAsSb Multilayers and Fabrication of Dual Band Photodetectors

    NASA Technical Reports Server (NTRS)

    Xiao, Ye-Gao; Bhat, Ishwara; Refaat, Tamer F.; Abedin, M. Nurul; Shao, Qing-Hui

    2005-01-01

    Metalorganic vapor phase epitaxy (MOVPE) of GaSb/InGaAsSb multilayer thin films and fabrication of bias-selectable dual band photodetectors are reported. For the dual band photodetectors the short wavelength detector, or the upper p- GaSb/n-GaSb junction photodiode, is placed optically ahead of the long wavelength one, or the lower photodiode. The latter is based on latticed-matched In0.13Ga0.87As0.11Sb0.89 with bandgap near 0.6 eV. Specifically, high quality multilayer thin films are grown sequentially from top to bottom as p+-GaSb/p-GaSb/n-GaSb/n-InGaAsSb/p-InGaAsSb/p-GaSb on undoped p-type GaSb substrate, and as n-GaSb/p-GaSb/p-InGaAsSb/n-InGaAsSb/n-GaSb on Te-doped n-type GaSb substrate respectively. The multilayer thin films are characterized by optical microscope, atomic force microscope (AFM), electron microprobe analyses etc. The photodiode mesa steps are patterned by photolithography with wet chemical etching and the front metallization is carried out by e-beam evaporation with Pd/Ge/Au/Ti/Au to give ohmic contact on both n- and p-type Sb based layer surfaces. Dark I-V measurements show typical diode behavior for both the upper and lower photodiodes. The photoresponsivity measurements indicate that both the upper and lower photodiodes can sense the infrared illumination corresponding to their cutoff wavelengths respectively, comparable with the simulation results. More work is underway to bring the long wavelength band to the medium infrared wavelength region near 4 micrometers.

  20. Rapid thermal anneal in InP, GaAs and GaAs/GaAlAs

    NASA Astrophysics Data System (ADS)

    Descouts, B.; Duhamel, N.; Godefroy, S.; Krauz, P.

    Ion implantation in semiconductors provides a doping technique with several advantages over more conventional doping methods and is now extensively used for device applications, e.g. field effect transistors (MESFET GaAs, MIS (InP), GaAs/GaAlAs heterojunction bipolar transistors (HBT). Because of the lattice disorder produced by the implantation, the dopant must be made electrically active by a postimplant anneal. As the device performances are very dependent on its electrical characteristics, the anneal is a very important stage of the process. Rapid anneal is known to provide less exodiffusion and less induffusion of impurities compared to conventional furnace anneal, so this technique has been used in this work to activate an n-type dopant (Si) in InP and a p-type dopant (Mg) in GaAs and GaAs/GaAIAs. These two ions have been chosen to realize implanted MIS InP and the base contacts for GaAs/GaAlAs HBTs. The experimental conditions to obtain the maximum electrical activity in these two cases will be detailed. For example, although we have not been able to obtain a flat profile in Mg + implanted GaAs/GaAlAs heterostructure by conventional thermal anneal, rapid thermal anneal gives a flat hole profile over a depth of 0.5 μm with a concentration of 1 x 10 19 cm -3.

  1. SEMICONDUCTOR DEVICES: AlGaN/GaN double-channel HEMT

    NASA Astrophysics Data System (ADS)

    Si, Quan; Yue, Hao; Xiaohua, Ma; Pengtian, Zheng; Yuanbin, Xie

    2010-04-01

    The fabrication of AlGaN/GaN double-channel high electron mobility transistors on sapphire substrates is reported. Two carrier channels are formed in an AlGaN/GaN/AlGaN/GaN multilayer structure. The DC performance of the resulting double-channel HEMT shows a wider high transconductance region compared with single-channel HEMT. Simulations provide an explanation for the influence of the double-channel on the high transconductance region. The buffer trap is suggested to be related to the wide region of high transconductance. The RF characteristics are also studied.

  2. Magnetism and transport properties of epitaxial Fe-Ga thin films on GaAs(001)

    SciTech Connect

    Duong Anh Tuan; Shin, Yooleemi; Cho, Sunglae; Dang Duc Dung; Vo Thanh Son

    2012-04-01

    Epitaxial Fe-Ga thin films in disordered bcc {alpha}-Fe crystal structure (A2) have been grown on GaAs(001) by molecular beam epitaxy. The saturated magnetization (M{sub S}) decreased from 1371 to 1105 kA/m with increasing Ga concentration from 10.5 to 24.3 % at room temperature. The lattice parameter increased with the increase in Ga content because of the larger atomic radius of Ga atom than that of Fe. The increase in carrier density with Ga content caused in lower resistivity.

  3. Medium energy proton radiation damage to (AlGa)As-GaAs solar cells

    NASA Technical Reports Server (NTRS)

    Loo, R. Y.; Kamath, G. S.; Knechtli, R. C.

    1982-01-01

    The performance of (AlGa)As-GaAs solar cells irradiated by medium energy 2, 5, and 10 MeV protons was evaluated. The Si cells without coverglass and a number of GaAs solar cells with 12 mil coverglass were irradiated simultaneously with bare GaAs cells. The cell degradation is directly related to the penetration of depth of protons with GaAs. The influence of periodic and continuous thermal annealing on the GaAs solar cells was investigated.

  4. X-band inverse class-F GaN internally-matched power amplifier

    NASA Astrophysics Data System (ADS)

    Zhao, Bo-Chao; Lu, Yang; Han, Wen-Zhe; Zheng, Jia-Xin; Zhang, Heng-Shuang; Ma, Pei-jun; Ma, Xiao-Hua; Hao, Yue

    2016-09-01

    An X-band inverse class-F power amplifier is realized by a 1-mm AlGaN/GaN high electron mobility transistor (HEMT). The intrinsic and parasitic components inside the transistor, especially output capacitor Cds, influence the harmonic impedance heavily at the X-band, so compensation design is used for meeting the harmonic condition of inverse class-F on the current source plane. Experiment results show that, in the continuous-wave mode, the power amplifier achieves 61.7% power added efficiency (PAE), which is 16.3% higher than the class-AB power amplifier realized by the same kind of HEMT. To the best of our knowledge, this is the first inverse class-F GaN internally-matched power amplifier, and the PAE is quite high at the X-band. Project supported by the National High Technology Research and Development Program of China (Grant No. 2015AA016801).

  5. 76 FR 25330 - Georgia Power Company; Project No. 485-063-Georgia and Alabama, Bartletts Ferry Hydroelectric...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-04

    ...., Company, 241 Ralph McGill Washington, DC 20004. Boulevard, NE., Bin 10221, Atlanta, GA 30308. Elizabeth... Ralph McGill South Perry Street, Montgomery, AL Boulevard, NE., Bin 10151, 36130-0900. Atlanta, GA...

  6. 2016 ACPA MEETING ABSTRACTS.

    PubMed

    2016-07-01

    The peer-reviewed abstracts presented at the 73rd Annual Meeting of the ACPA are published as submitted by the authors. For financial conflict of interest disclosure, please visit http://meeting.acpa-cpf.org/disclosures.html. PMID:27447885

  7. 77 FR 36479 - Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-19

    ... From the Federal Register Online via the Government Publishing Office ARCHITECTURAL AND TRANSPORTATION BARRIERS COMPLIANCE BOARD Meetings AGENCY: Architectural and Transportation Barriers Compliance Board. ACTION: Notice of meetings. SUMMARY: The Architectural and Transportation Barriers...

  8. 75 FR 13075 - Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-18

    ... From the Federal Register Online via the Government Publishing Office ARCHITECTURAL AND TRANSPORTATION BARRIERS COMPLIANCE BOARD Meetings AGENCY: Architectural and Transportation Barriers Compliance Board. ACTION: Notice of meetings. SUMMARY: The Architectural and Transportation Barriers...

  9. 76 FR 10557 - Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-25

    ... From the Federal Register Online via the Government Publishing Office ARCHITECTURAL AND TRANSPORTATION BARRIERS COMPLIANCE BOARD Meetings AGENCY: Architectural and Transportation Barriers Compliance Board. ACTION: Notice of meetings. SUMMARY: The Architectural and Transportation Barriers...

  10. 75 FR 66061 - Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-27

    ... From the Federal Register Online via the Government Publishing Office ARCHITECTURAL AND TRANSPORTATION BARRIERS COMPLIANCE BOARD Meetings AGENCY: Architectural and Transportation Barriers Compliance Board. ACTION: Notice of meetings. SUMMARY: The Architectural and Transportation Barriers...

  11. 77 FR 51513 - Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-24

    ... From the Federal Register Online via the Government Publishing Office ARCHITECTURAL AND TRANSPORTATION BARRIERS COMPLIANCE BOARD Meetings AGENCY: Architectural and Transportation Barriers Compliance Board. ACTION: Notice of meetings. SUMMARY: The Architectural and Transportation Barriers...

  12. 77 FR 74827 - Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-18

    ... From the Federal Register Online via the Government Publishing Office ARCHITECTURAL AND TRANSPORTATION BARRIERS COMPLIANCE BOARD Meetings AGENCY: Architectural and Transportation Barriers Compliance Board. ACTION: Notice of meetings. SUMMARY: The Architectural and Transportation Barriers...

  13. 78 FR 12715 - Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-25

    ... From the Federal Register Online via the Government Publishing Office ARCHITECTURAL AND TRANSPORTATION BARRIERS COMPLIANCE BOARD Meetings AGENCY: Architectural and Transportation Barriers Compliance Board. ACTION: Notice of meetings. SUMMARY: The Architectural and Transportation Barriers...

  14. Engineering of electric field distribution in GaN(cap)/AlGaN/GaN heterostructures: theoretical and experimental studies

    NASA Astrophysics Data System (ADS)

    Gladysiewicz, M.; Janicki, L.; Misiewicz, J.; Sobanska, M.; Klosek, K.; Zytkiewicz, Z. R.; Kudrawiec, R.

    2016-09-01

    Polarization engineering of GaN-based heterostructures opens a way to develop advanced transistor heterostructures, although measurement of the electric field in such heterostructures is not a simple task. In this work, contactless electroreflectance (CER) spectroscopy has been applied to measure the electric field in GaN-based heterostructures. For a set of GaN(d  =  0, 5, 15, and 30 nm)/AlGaN(20 nm)/GaN(buffer) heterostructures a decrease of electric field in the GaN(cap) layer from 0.66 MV cm-1 to 0.27 MV cm-1 and an increase of the electric field in the AlGaN layer from 0.57 MV cm-1 to 0.99 MV cm-1 have been observed with the increase in the GaN(cap) thickness from 5-30 nm. For a set of GaN(20 nm)/AlGaN(d  =  10, 20, 30, and 40 nm)/GaN(buffer) heterostructures a decrease of the electric field in the AlGaN layer from 1.77 MV cm-1 to 0.64 MV cm-1 and an increase of the electric field in the GaN layer from 0.57 MV cm-1 to 0.99 MV cm-1 were observed with the increase in the AlGaN thickness from 10-40 nm. To determine the distribution of the electric field in these heterostructures the Schrödinger and Poisson equations are solved in a self-consistent manner and matched with experimental data. It is shown that the built-in electric field in the GaN(cap) and AlGaN layers obtained from measurements does not reach values of electric field resulting only from polarization effects. The measured electric fields are smaller due to a screening of polarization effects by free carriers, which are inhomogeneously distributed across the heterostructure and accumulate at interfaces. The results clearly demonstrate that CER measurements supported by theoretical calculations are able to determine the electric field distribution in GaN-based heterostructures quantitatively, which is very important for polarization engineering in this material system.

  15. Engineering of electric field distribution in GaN(cap)/AlGaN/GaN heterostructures: theoretical and experimental studies

    NASA Astrophysics Data System (ADS)

    Gladysiewicz, M.; Janicki, L.; Misiewicz, J.; Sobanska, M.; Klosek, K.; Zytkiewicz, Z. R.; Kudrawiec, R.

    2016-09-01

    Polarization engineering of GaN-based heterostructures opens a way to develop advanced transistor heterostructures, although measurement of the electric field in such heterostructures is not a simple task. In this work, contactless electroreflectance (CER) spectroscopy has been applied to measure the electric field in GaN-based heterostructures. For a set of GaN(d  =  0, 5, 15, and 30 nm)/AlGaN(20 nm)/GaN(buffer) heterostructures a decrease of electric field in the GaN(cap) layer from 0.66 MV cm‑1 to 0.27 MV cm‑1 and an increase of the electric field in the AlGaN layer from 0.57 MV cm‑1 to 0.99 MV cm‑1 have been observed with the increase in the GaN(cap) thickness from 5–30 nm. For a set of GaN(20 nm)/AlGaN(d  =  10, 20, 30, and 40 nm)/GaN(buffer) heterostructures a decrease of the electric field in the AlGaN layer from 1.77 MV cm‑1 to 0.64 MV cm‑1 and an increase of the electric field in the GaN layer from 0.57 MV cm‑1 to 0.99 MV cm‑1 were observed with the increase in the AlGaN thickness from 10–40 nm. To determine the distribution of the electric field in these heterostructures the Schrödinger and Poisson equations are solved in a self-consistent manner and matched with experimental data. It is shown that the built-in electric field in the GaN(cap) and AlGaN layers obtained from measurements does not reach values of electric field resulting only from polarization effects. The measured electric fields are smaller due to a screening of polarization effects by free carriers, which are inhomogeneously distributed across the heterostructure and accumulate at interfaces. The results clearly demonstrate that CER measurements supported by theoretical calculations are able to determine the electric field distribution in GaN-based heterostructures quantitatively, which is very important for polarization engineering in this material system.

  16. Theoretical studies on ultraviolet nearly lattice-matched BAlGaN/BAlGaN quantum well structures with quaternary BAlGaN barriers

    NASA Astrophysics Data System (ADS)

    Park, Seoung-Hwan; Ahn, Doyeol

    2016-07-01

    Light emission characteristics of B x Al y Ga1- x - y N/BAlGaN quantum well (QW) structures with quaternary BAlGaN barrier were investigated using the multiband effective-mass theory. The internal field in the BAlGaN well of the BAlGaN/AlN QW structure is shown to be large (˜10 MV/cm) under the lattice-matched condition (ɛ = 0.0%). On the other hand, the internal field is significantly reduced by using BAlGaN barrier and the peak intensity of the spontaneous emission coefficient of the lattice-matched BAlGaN/BAlGaN QW structure is comparable to that of the conventional BAlGaN/AlN QW structure. We observe that the light intensity of the lattice-matched BAlGaN/BAlGaN QW structure is comparable to that of the conventional BAlGaN/AlN QW structure. Also, we observe that the nearly lattice-matched BAlGaN/BAlGaN QW structure with small strain (0.5%) has about 3 times larger peak intensity than the conventional QW AlGaN/AlN structure. Hence, BAlGaN/BAlGaN QW system could be used as a UV light source with a higher light emission and a higher crystal quality, compared to conventional AlGaN/AlN QW structures with larger strain (1.78%).

  17. Improvement of crystallinity of GaN layers grown using Ga2O vapor synthesized from liquid Ga and H2O vapor

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Yohei; Taniyama, Yuuki; Takatsu, Hiroaki; Kitamoto, Akira; Imade, Mamoru; Yoshimura, Masashi; Isemura, Masashi; Mori, Yusuke

    2016-05-01

    Growth methods using Ga2O vapor allow long-term growth of bulk GaN crystals. Ga2O vapor is generated by the reduction of Ga2O3 powder with H2 gas (Ga2O3-H2 process) or by the oxidation of liquid Ga with H2O vapor (Ga-H2O process). We investigated the dependence of the properties of grown GaN layers on the synthesis of Ga2O. In the Ga-H2O process, the polycrystal density and full width at half maximum (FWHM) GaN(0002) X-ray rocking curves (XRC) at a high growth rate were lower than those in the Ga2O3-H2 process, and a GaN layer with FWHM of 99 arcsec and growth rate of 216 µm/h was obtained. A low H2O partial pressure in the growth zone improved crystallinity in the Ga-H2O process, realized by the high efficiency of conversion from liquid Ga to Ga2O vapor. We concluded that using Ga2O vapor in the Ga-H2O process has the potential for obtaining higher crystallinity with high growth rate.

  18. InGaP/GaAs and InGaAs mechanically-stacked triple-junction solar cells

    SciTech Connect

    Takamoto, T.; Ikeda, E.; Agui, T.

    1997-12-31

    Triple-junction cells with AM1.5 efficiencies of over 33% have been demonstrated. A planar type InGaP/GaAs monolithic dual-junction cell was fabricated on a semi-insulating FaAs substrate, which has high infra-red transparency. Then a dual-junction cell, with efficiency of 27--28%, was mechanically stacked on an InGaAs cell fabricated on an InP substrate. The bottom InGaAs cell showed an efficiency of 6.2% under the InGaP/GaAs cell, and a total efficiency of 33--34% was achieved for the four-terminal triple-junction cell.

  19. Internal quantum efficiency in yellow-amber light emitting AlGaN-InGaN-GaN heterostructures

    SciTech Connect

    Ngo, Thi Huong; Gil, Bernard; Valvin, Pierre; Damilano, Benjamin; Lekhal, Kaddour; De Mierry, Philippe

    2015-09-21

    We determine the internal quantum efficiency of strain-balanced AlGaN-InGaN-GaN hetero-structures designed for yellow-amber light emission, by using a recent model based on the kinetics of the photoluminescence decay initiated by Iwata et al. [J. Appl. Phys. 117, 075701 (2015)]. Our results indicate that low temperature internal quantum efficiencies sit in the 50% range and we measure that adding an AlGaN layer increases the internal quantum efficiency from 50% up to 57% with respect to the GaN-InGaN case. More dramatic, it almost doubles from 2.5% up to 4.3% at room temperature.

  20. 75 FR 58350 - Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-24

    ... RESEARCH COMMISSION Meeting Notice is hereby given that the U.S. Arctic Research Commission will hold its... presentations concerning Arctic research activities. The focus of the meeting will be reports and updates on programs and research projects affecting the Arctic. If you plan to attend this meeting, please notify...

  1. Managing Magnificent Meetings

    ERIC Educational Resources Information Center

    Christianson, Becky

    2005-01-01

    Though trustees may communicate informally via telephone or e-mail, the board's formal meetings are the primary setting in which issues of great consequence are discussed and decided. That's why it is vital for those responsible for planning board meetings to be certain each meeting accomplishes the business at hand. Beyond common sense, planning…

  2. Progress in GaAs/CuInSe2 tandem junction solar cells

    NASA Technical Reports Server (NTRS)

    Kim, N. P.; Burgess, R. M.; Mickelsen, R. A.; Stanbery, B. J.; Mcclelland, R. W.; King, B. D.; Gale, R. P.

    1991-01-01

    Much more power is required for spacecraft of the future than current vehicles. To meet this increased demand for power while simultaneously meeting other requirements for launch, deployment, and maneuverability, the development of higher-efficiency, lighter-weight, and more radiation resistant photovoltaic cells is essential. Mechanically stacked tandem junction solar cells based on (AlGaAs)GaAs thin film CLEFT (Cleavage of Lateral Epitaxial Film for Transfer) top cells and CuInSe2(CIS) thin film bottom cells are being developed to meet these power needs. The mechanically stacked tandem configuration is chosen due to its interconnect flexibility allowing more efficient array level performance. It also eliminates cell fabrication processing constraints associated with monolithically integrated multi-junction approaches, thus producing higher cell fabrication yields. The GaAs cell is used as the top cell due to its demonstrated high efficiency, and good radiation resistance. Furthermore, it offers a future potential for bandgap tuning using AlGaAs as the absorber to maximize cell performance. The CuInSe2 cell is used as the bottom cell due to superb radiation resistance, stability, and optimal bandgap value in combination with an AlGaAs top cell. Since both cells are incorporated as thin films, this approach provides a potential for very high specific power. This high specific power (W/kg), combined with high power density (W/sq m) resulting from the high efficiency of this approach, makes these cells ideally suited for various space applications.

  3. GaN Electronics For High Power, High Temperature Applications

    SciTech Connect

    PEARTON,S.J.; REN,F.; ZHANG,A.P.; DANG,G.; CAO,X.A.; LEE,K.P.; CHO,H.; GILA,B.P.; JOHNSON,J.W.; MONIER,C.; ABERNATHY,C.R.; HAN,JUNG; BACA,ALBERT G.; CHYI,J.-I.; LEE,C.-M.; NEE,T.-E.; CHUO,C.-C.; CHU,S.N.G.

    2000-06-12

    A brief review is given of recent progress in fabrication of high voltage GaN and AlGaN rectifiers. GaN/AlGaN heterojunction bipolar transistors and GaN metal-oxide semiconductor field effect transistors. Improvements in epitaxial layer quality and in fabrication techniques have led to significant advances in device performance.

  4. Ultra-Thin, Triple-Bandgap GaInP/GaAs/GaInAs Monolithic Tandem Solar Cells

    SciTech Connect

    Wanlass, M. W.; Ahrenkiel, S. P.; Albin, D. S.; Carapella, J. J.; Duda, A.; Emery, K.; Geisz, J. F.; Jones, K.; Kurtz, S.; Moriarty, T.; Romero, M. J.

    2007-02-01

    The performance of state-of-the-art, series-connected, lattice-matched (LM), triple-junction (TJ), III-V tandem solar cells could be improved substantially (10-12%) by replacing the Ge bottom subcell with a subcell having a bandgap of {approx}1 eV. For the last several years, research has been conducted by a number of organizations to develop {approx}1-eV, LM GaInAsN to provide such a subcell, but, so far, the approach has proven unsuccessful. Thus, the need for a high-performance, monolithically integrable, 1-eV subcell for TJ tandems has remained. In this paper, we present a new TJ tandem cell design that addresses the above-mentioned problem. Our approach involves inverted epitaxial growth to allow the monolithic integration of a lattice-mismatched (LMM) {approx}1-eV GaInAs/GaInP double-heterostructure (DH) bottom subcell with LM GaAs (middle) and GaInP (top) upper subcells. A transparent GaInP compositionally graded layer facilitates the integration of the LM and LMM components. Handle-mounted, ultra-thin device fabrication is a natural consequence of the inverted-structure approach, which results in a number of advantages, including robustness, potential low cost, improved thermal management, incorporation of back-surface reflectors, and possible reclamation/reuse of the parent crystalline substrate for further cost reduction. Our initial work has concerned GaInP/GaAs/GaInAs tandem cells grown on GaAs substrates. In this case, the 1-eV GaInAs experiences 2.2% compressive LMM with respect to the substrate. Specially designed GaInP graded layers are used to produce 1-eV subcells with performance parameters nearly equaling those of LM devices with the same bandgap (e.g., LM, 1-eV GaInAsP grown on InP). Previously, we reported preliminary ultra-thin tandem devices (0.237 cm{sup 2}) with NREL-confirmed efficiencies of 31.3% (global spectrum, one sun) (1), 29.7% (AM0 spectrum, one sun) (2), and 37.9% (low-AOD direct spectrum, 10.1 suns) (3), all at 25 C. Here, we

  5. Tuning emission in violet, blue, green and red in cubic GaN/InGaN/GaN quantum wells

    NASA Astrophysics Data System (ADS)

    Orozco Hinostroza, I. E.; Avalos-Borja, M.; Compeán García, V. D.; Zamora, C. Cuellar; Rodríguez, A. G.; López Luna, E.; Vidal, M. A.

    2016-02-01

    Light emission in the three primary colors was achieved in cubic GaN/InGaN/GaN heterostructures grown by molecular beam epitaxy on MgO substrates in a single growth process. A heterostructure with four quantum wells with a width of 10 nm was grown; this quantum wells width decrease the segregation effect of In. Photoluminescence emission produced four different emission signals: violet, blue, green-yellow and red. Thus, we were able to tune energy transitions in the visible spectrum modifying the In concentration in cubic InxGa1-xN ternary alloy.

  6. Ultra-Thin, Triple-Bandgap GaInP/GaAs/GaInAs Monolithic Tandem Solar Cells

    NASA Technical Reports Server (NTRS)

    Wanlass, M. W.; Ahrenkiel, S. P.; Albin, D. S.; Carapella, J. J.; Duda, A.; Emery, K.; Geisz, J. F.; Jones, K.; Kurtz, Sarah; Moriarty, T.; Romero, M. J.

    2007-01-01

    The performance of state-of-the-art, series-connected, lattice-matched (LM), triple-junction (TJ), III-V tandem solar cells could be improved substantially (10-12%) by replacing the Ge bottom subcell with a subcell having a bandgap of approx.1 eV. For the last several years, research has been conducted by a number of organizations to develop approx.1-eV, LM GaInAsN to provide such a subcell, but, so far, the approach has proven unsuccessful. Thus, the need for a high-performance, monolithically integrable, 1-eV subcell for TJ tandems has remained. In this paper, we present a new TJ tandem cell design that addresses the above-mentioned problem. Our approach involves inverted epitaxial growth to allow the monolithic integration of a lattice-mismatched (LMM) approx.1- eV GaInAs/GaInP double-heterostructure (DH) bottom subcell with LM GaAs (middle) and GaInP (top) upper subcells. A transparent GaInP compositionally graded layer facilitates the integration of the LM and LMM components. Handle-mounted, ultra-thin device fabrication is a natural consequence of the inverted-structure approach, which results in a number of advantages, including robustness, potential low cost, improved thermal management, incorporation of back-surface reflectors, and possible reclamation/reuse of the parent crystalline substrate for further cost reduction. Our initial work has concerned GaInP/GaAs/GaInAs tandem cells grown on GaAs substrates. In this case, the 1- eV GaInAs experiences 2.2% compressive LMM with respect to the substrate. Specially designed GaInP graded layers are used to produce 1-eV subcells with performance parameters nearly equaling those of LM devices with the same bandgap (e.g., LM, 1-eV GaInAsP grown on InP). Previously, we reported preliminary ultra-thin tandem devices (0.237 cm2) with NREL-confirmed efficiencies of 31.3% (global spectrum, one sun) (1), 29.7% (AM0 spectrum, one sun) (2), and 37.9% (low-AOD direct spectrum, 10.1 suns) (3), all at 25 C. Here, we include

  7. Optical and magnetotransport properties of InGaAs/GaAsSb/GaAs structures doped with a magnetic impurity

    SciTech Connect

    Kalentyeva, I. L. Zvonkov, B. N.; Vikhrova, O. V.; Danilov, Yu. A.; Demina, P. B.; Dorokhin, M. V.; Zdoroveyshchev, A. V.

    2015-11-15

    InGaAs/GaAsSb/GaAs bilayer quantum-well structures containing a magnetic-impurity δ-layer (Mn) at the GaAs/InGaAs interface are experimentally studied for the first time. The structures are fabricated by metal organic chemical-vapor deposition (MOCVD) and laser deposition on substrates of conducting (n{sup +}) and semi-insulating GaAs in a single growth cycle. The InGaAs-layer thickness is varied from 1.5 to 5 nm. The significant effect of a decrease in the InGaAs quantum-well thickness on the optical and magnetotransport properties of the structures under study is detected. Nonlinear magnetic-field dependence of the Hall resistance and negative magnetoresistance at temperatures of ≤30–40 K, circular polarization of the electroluminescence in a magnetic field, opposite behaviors of the photoluminescence and electroluminescence emission intensities in the structures, and an increase in the contribution of indirect transitions with decreasing InGaAs thickness are observed. Simulation shows that these effects can be caused by the influence of the δ-layer of acceptor impurity (Mn) on the band structure and the hole concentration distribution in the bilayer quantum well.

  8. Sc(2)MgGa(2) and Y(2)MgGa(2).

    PubMed

    Sahlberg, Martin; Andersson, Yvonne

    2009-03-01

    Scandium magnesium gallide, Sc(2)MgGa(2), and yttrium magnesium gallide, Y(2)MgGa(2), were synthesized from the corresponding elements by heating under an argon atmosphere in an induction furnace. These intermetallic compounds crystallize in the tetragonal Mo(2)FeB(2)-type structure. All three crystallographically unique atoms occupy special positions and the site symmetries of (Sc/Y, Ga) and Mg are m2m and 4/m, respectively. The coordinations around Sc/Y, Mg and Ga are pentagonal (Sc/Y), tetragonal (Mg) and triangular (Ga) prisms, with four (Mg) or three (Ga) additional capping atoms leading to the coordination numbers [10], [8+4] and [6+3], respectively. The crystal structure of Sc(2)MgGa(2 )was determined from single-crystal diffraction intensities and the isostructural Y(2)MgGa(2) was identified from powder diffraction data. PMID:19265212

  9. GaAsP solar cells on GaP/Si with low threading dislocation density

    NASA Astrophysics Data System (ADS)

    Yaung, Kevin Nay; Vaisman, Michelle; Lang, Jordan; Lee, Minjoo Larry

    2016-07-01

    GaAsP on Si tandem cells represent a promising path towards achieving high efficiency while leveraging the Si solar knowledge base and low-cost infrastructure. However, dislocation densities exceeding 108 cm-2 in GaAsP cells on Si have historically hampered the efficiency of such approaches. Here, we report the achievement of low threading dislocation density values of 4.0-4.6 × 106 cm-2 in GaAsP solar cells on GaP/Si, comparable with more established metamorphic solar cells on GaAs. Our GaAsP solar cells on GaP/Si exhibit high open-circuit voltage and quantum efficiency, allowing them to significantly surpass the power conversion efficiency of previous devices. The results in this work show a realistic path towards dual-junction GaAsP on Si cells with efficiencies exceeding 30%.

  10. Sc(2)MgGa(2) and Y(2)MgGa(2).

    PubMed

    Sahlberg, Martin; Andersson, Yvonne

    2009-03-01

    Scandium magnesium gallide, Sc(2)MgGa(2), and yttrium magnesium gallide, Y(2)MgGa(2), were synthesized from the corresponding elements by heating under an argon atmosphere in an induction furnace. These intermetallic compounds crystallize in the tetragonal Mo(2)FeB(2)-type structure. All three crystallographically unique atoms occupy special positions and the site symmetries of (Sc/Y, Ga) and Mg are m2m and 4/m, respectively. The coordinations around Sc/Y, Mg and Ga are pentagonal (Sc/Y), tetragonal (Mg) and triangular (Ga) prisms, with four (Mg) or three (Ga) additional capping atoms leading to the coordination numbers [10], [8+4] and [6+3], respectively. The crystal structure of Sc(2)MgGa(2 )was determined from single-crystal diffraction intensities and the isostructural Y(2)MgGa(2) was identified from powder diffraction data.

  11. Improvement of interface electronic properties of GaF 3/GaAs MIS structures

    NASA Astrophysics Data System (ADS)

    Ricard, H.; Aizawa, K.; Ishiwara, H.

    The interface electronic properties of GaF 3/GaAs structures are investigated for three different deposition procedures, the GaF 3 films have been deposited on n-type GaAs epitaxial layers without breaking the vacuum, or after being exposed to air, or after being treated in (NH 4) 2S 1 solution. It has been found from low-temperature C-V measurements in MIS diodes that a real modulation of the Fermi level in the forbidden band gap of GaAs occurs only when the GaAs epitaxial layer is treated in the sulfur solution and annealed at an optimum temperature prior to deposition of GaF 3. The unpinning mechanism is also discussed in conjunction with the simplified model for sulfur-treated GaAs surfaces.

  12. White emission from non-planar InGaN/GaN MQW LEDs grown on GaN template with truncated hexagonal pyramids.

    PubMed

    Lee, Ming-Lun; Yeh, Yu-Hsiang; Tu, Shang-Ju; Chen, P C; Lai, Wei-Chih; Sheu, Jinn-Kong

    2015-04-01

    Non-planar InGaN/GaN multiple quantum well (MQW) structures are grown on a GaN template with truncated hexagonal pyramids (THPs) featuring c-plane and r-plane surfaces. The THP array is formed by the regrowth of the GaN layer on a selective-area Si-implanted GaN template. Transmission electron microscopy shows that the InGaN/GaN epitaxial layers regrown on the THPs exhibit different growth rates and indium compositions of the InGaN layer between the c-plane and r-plane surfaces. Consequently, InGaN/GaN MQW light-emitting diodes grown on the GaN THP array emit multiple wavelengths approaching near white light.

  13. Theoretical and experimental studies of electric field distribution in N-polar GaN/AlGaN/GaN heterostructures

    SciTech Connect

    Gladysiewicz, M. Janicki, L.; Kudrawiec, R.; Siekacz, M.; Cywinski, G.

    2015-12-28

    Electric field distribution in N-polar GaN(channel)/AlGaN/GaN(buffer) heterostructures was studied theoretically by solving Schrodinger and Poisson equations in a self-consistent manner for various boundary conditions and comparing results of these calculations with experimental data, i.e., measurements of electric field in GaN(channel) and AlGaN layers by electromodulation spectroscopy. A very good agreement between theoretical calculations and experimental data has been found for the Fermi-level located at ∼0.3 eV below the conduction band at N-polar GaN surface. With this surface boundary condition, the electric field distribution and two dimensional electron gas concentration are determined for GaN(channel)/AlGaN/GaN(buffer) heterostructures of various thicknesses of GaN(channel) and AlGaN layers.

  14. GaAs solar cell development

    NASA Technical Reports Server (NTRS)

    Knechtli, R. C.; Kamath, S.; Loo, R.

    1977-01-01

    The motivation for developing GaAs solar cells is based on their superior efficiency when compared to silicon cells, their lower degradation with increasing temperature, and the expectation for better resistance to space radiation damage. The AMO efficiency of GaAs solar cells was calculated. A key consideration in the HRL technology is the production of GaAs cells of large area (greater than 4 sg cm) at a reasonable cost without sacrificing efficiency. An essential requirement for the successful fabrication of such cells is the ability to grow epitaxially a uniform layer of high quality GaAs (buffer layer) on state-of-the-art GaAs substrates, and to grow on this buffer layer the required than layer of (AlGa)As. A modified infinite melt liquid phase epitaxy (LPE) growth technique is detailed.

  15. Characteristics study of 2DEG transport properties of AlGaN/GaN and AlGaAs/GaAs-based HEMT

    SciTech Connect

    Lenka, T. R. Panda, A. K.

    2011-05-15

    Growth of wide bandgap material over narrow bandgap material, results into a two dimensional electron gas (2DEG) at the heterointerface due to the conduction band discontinuity. In this paper the 2DEG transport properties of AlGaN/GaN-based high electron mobility transistor (HEMT) is discussed and its effect on various characteristics such as 2DEG density, C-V characteristics and Sheet resistances for different mole fractions are presented. The obtained results are also compared with AlGaAs/GaAs-based HEMT for the same structural parameter as like AlGaN/GaN-based HEMT. The calculated results of electron sheet concentration as a function of the Al mole fraction are in excellent agreement with some experimental data available in the literature.

  16. NpN-GaN/InxGa1-xN/GaN heterojunction bipolar transistor on free-standing GaN substrate

    NASA Astrophysics Data System (ADS)

    Lochner, Zachary; Jin Kim, Hee; Lee, Yi-Che; Zhang, Yun; Choi, Suk; Shen, Shyh-Chiang; Doug Yoder, P.; Ryou, Jae-Hyun; Dupuis, Russell D.

    2011-11-01

    Data and analysis are presented for NpN-GaN/InGaN/GaN double-heterojunction bipolar transistors (HBTs) grown and fabricated on a free-standing GaN (FS-GaN) substrate in comparison to that on a sapphire substrate to investigate the effect of dislocations in III-nitride HBT epitaxial structures. The performance characteristics of HBTs on FS-GaN exhibit a maximum collector current density of ˜12.3 kA/cm2, dc current gain of ˜90, and maximum differential gain of ˜120 without surface passivation, representing a substantial improvement over similar devices grown on sapphire. This is attributed to the reduction in threading dislocation density afforded by using a homoepitaxial growth on a high-crystalline-quality substrate. The minority carrier diffusion length increases significantly owing to not only a mitigated carrier trap effect via fewer dislocations, but also possibly reduced microscopic localized states.

  17. Strain-balanced InGaN/GaN multiple quantum wells

    SciTech Connect

    Van Den Broeck, D. M.; Hosalli, A. M.; Bedair, S. M.; Bharrat, D.; El-Masry, N. A.

    2014-07-21

    InGaN/GaN multiple quantum well (MQW) structures suffer from a high amount of compressive strain in the InGaN wells and the accompanied piezoelectric field resulting in both a blue shift in emission and a reduction of emission intensity. We report the growth of In{sub x}Ga{sub 1−x}N/GaN “strain-balanced” multiple quantum wells (SBMQWs) grown on thick In{sub y}Ga{sub 1−y}N templates for x > y by metal organic chemical vapor deposition. SBMQWs consist of alternating layers of In{sub x}Ga{sub 1−x}N wells and GaN barriers under compressive and tensile stress, respectively, which have been lattice matched to a thick In{sub y}Ga{sub 1−y}N template. Growth of the In{sub y}Ga{sub 1−y}N template is also detailed in order to achieve thick, relaxed In{sub y}Ga{sub 1−y}N grown on GaN without the presence of V-grooves. When compared to conventional In{sub x}Ga{sub 1−x}N/GaN MQWs grown on GaN, the SBMQW structures exhibit longer wavelength emission and higher emission intensity for the same InN mole fraction due to a reduction in the well strain and piezoelectric field. By matching the average lattice constant of the MQW active region to the lattice constant of the In{sub y}Ga{sub 1−y}N template, essentially an infinite number of periods can be grown using the SBMQW growth method without relaxation-related effects. SBMQWs can be utilized to achieve longer wavelength emission in light emitting diodes without the use of excess indium and can be advantageous in addressing the “green gap.”.

  18. Interfacial Reactions in Cu/Ga and Cu/Ga/Cu Couples

    NASA Astrophysics Data System (ADS)

    Lin, Shih-kang; Cho, Cheng-liang; Chang, Hao-miao

    2014-01-01

    Cu-to-Cu bonding to connect through-silicon vias in three-dimensional integrated-circuit packaging is the most important interconnection technology in the next-generation semiconductor industry. Soldering is an economic and fast process in comparison with diffusion bonding methods. Ga has high solubility of up to 20 at.% in the Cu-rich face-centered cubic (FCC) phase and high mobility at moderate temperatures. In this work, an attempt has been made to evaluate Ga-based Cu-to-Cu interconnection by transient liquid-phase (TLP) bonding. The Cu/Ga interfacial reactions at temperatures ranging from 160°C to 300°C were examined. For reactions at temperatures lower than 240°C, the reaction path is Cu/ γ 3-Cu9Ga4/ θ-CuGa2/liquid, where the γ 3-Cu9Ga4 and θ-CuGa2 phases are thin planar and thick scalloped layers, respectively, while for the reactions at 280°C and 300°C, the scalloped γ 3-Cu9Ga4 phase is the only reaction product. The phase transformation kinetics, reaction mechanisms, and microstructural evolution in the Cu/Ga couples are elaborated. In addition, reactions of Cu/Ga/Cu sandwich couples at 160°C were investigated. The original Cu/liquid/Cu couples isothermally transformed to Cu/ γ 3-Cu9Ga4/ θ-CuGa2/ γ 3-Cu9Ga4/Cu couples as the reaction progressed. However, cracks were observed in the θ-CuGa2 phase regions after metallographic processing. The brittle θ-CuGa2 phase is undesirable for Ga-based TLP bonding.

  19. (In,Ga)As/GaP electrical injection quantum dot laser

    SciTech Connect

    Heidemann, M. Höfling, S.; Kamp, M.

    2014-01-06

    The paper reports on the realization of multilayer (In,Ga)As/GaP quantum dot (QD) lasers grown by gas source molecular beam epitaxy. The QDs have been embedded in (Al,Ga)P/GaP waveguide structures. Laser operation at 710 nm is obtained for broad area laser devices with a threshold current density of 4.4 kA/cm{sup 2} at a heat-sink temperature of 80 K.

  20. Abiological origin of described stromatolites older than 3.2 Ga.

    PubMed

    Lowe, D R

    1994-05-01

    The three well-documented occurrences of three-dimensional stromatolites older than 3.2 Ga meet most criteria for biogenicity except the presence of fossil bacteria. However, they also show features more consistent with nonbiological origins. Small conical structures in the Strelley Pool chert in the upper part of the Warrawoona Group (3.5-3.2 Ga), Western Australia, lack the structure typical of stromatolites and probably formed mainly through evaporitc precipitation. A domal structure from the North Pole chert, Warrawoona Group, formed by soft-sediment deformation or originally flat layers. Laminated chert containing domal and pseudocolumnar structures in the Onverwacht Group (3.5-3.3 Ga), Barberton Greenstone Belt, South Africa, extends downward into veins and cavities, where it formed through inorganic precipitation. Although bacterial communities were widespread on Earth prior to 3.2 Ga, these particular three-dimensional structures are probably abiotic in origin and do not provide information on the paleobiology or paleoecology of early organisms. The paucity of Archean stromatolites older than 3.2 Ga probably reflects the paucity of known and possibly extant carbonate deposits of this age.

  1. Abiological origin of described stromatolites older than 3.2 Ga

    NASA Technical Reports Server (NTRS)

    Lowe, D. R.

    1994-01-01

    The three well-documented occurrences of three-dimensional stromatolites older than 3.2 Ga meet most criteria for biogenicity except the presence of fossil bacteria. However, they also show features more consistent with nonbiological origins. Small conical structures in the Strelley Pool chert in the upper part of the Warrawoona Group (3.5-3.2 Ga), Western Australia, lack the structure typical of stromatolites and probably formed mainly through evaporitc precipitation. A domal structure from the North Pole chert, Warrawoona Group, formed by soft-sediment deformation or originally flat layers. Laminated chert containing domal and pseudocolumnar structures in the Onverwacht Group (3.5-3.3 Ga), Barberton Greenstone Belt, South Africa, extends downward into veins and cavities, where it formed through inorganic precipitation. Although bacterial communities were widespread on Earth prior to 3.2 Ga, these particular three-dimensional structures are probably abiotic in origin and do not provide information on the paleobiology or paleoecology of early organisms. The paucity of Archean stromatolites older than 3.2 Ga probably reflects the paucity of known and possibly extant carbonate deposits of this age.

  2. Effect of Ga on the Wettability of CuGa10 on 304L Steel

    NASA Astrophysics Data System (ADS)

    Silze, Frank; Wiehl, Gunther; Kaban, Ivan; Kühn, Uta; Eckert, Jürgen; Pauly, Simon

    2015-08-01

    In the present work, the effect of Ga on the wetting behavior of the Cu-rich braze filler CuGa10 (wt pct, Cu90.8Ga9.2 at. pct) on the steel 304L was investigated. For this, the macroscopic and microscopic effects governing the wetting of pure Ga, pure Cu, and CuGa10 alloy (wt pct) on the austenitic steel were analyzed and compared. Contact angle and surface tension measurements were carried out by means of the sessile drop technique, and, in addition, the phase formation at the interface was determined. Pure liquid Ga spreads on 304L, which supposedly is related to the formation of intermetallic Fe-Ga phases growing into the liquid Ga. Depending on the annealing time, FeGa3 and Fe14.5Ga12 were identified. In contrast, CuGa10 as well as pure Cu shows secondary wetting on the steel surface. Especially, liquid Cu prefers spreading laterally and vertically along the grain boundaries of the steel substrate. In spite of rather similar mechanisms, CuGa10 wets 304L steel at lower rate than pure Cu above the liquidus temperature.

  3. Performance characteristics of InGaAs/GaAs and GaAs/InGaAlAs coherently strained superlattice photodiodes

    NASA Technical Reports Server (NTRS)

    Das, Utpal; Zebda, Yousef; Bhattacharya, Pallab; Chin, Albert

    1987-01-01

    The properties of In(0.24)Ga(0.76)As/GaAs and GaAs/In(0.05)Ga(0.58)Al(0.37)As superlattice photodiodes grown by molecular beam epitaxy have been investigated. From the temporal response characteristics, deconvolved rise times about 60-100 ps are obtained. The measured responsivities of the photodiodes with dark currents of 5-10 nA at 10 V are about 0.4 A/W, which correspond to peak external quantum efficiencies of about 60 percent. These results indicate that very high performance photodiodes can be realized with strained layers.

  4. Racial differences in the accuracy of perceived partner HIV status among men who have sex with men (MSM) in Atlanta, Georgia.

    PubMed

    Grey, Jeremy A; Rothenberg, Richard; Sullivan, Patrick S; Rosenberg, Eli S

    2015-01-01

    We compared perceptions of partner HIV status to HIV test results in a cross-sectional study of sexual networks of men who have sex with men (MSM) in Atlanta. We then examined differences between black and white MSM in the predictive value of perceived partner status. We recruited men ("seeds") using time-space venue sampling. These seeds then referred up to three partners, who could also refer partners. All participants reported sexual behavior and HIV status for recent partners and received HIV tests. For partners who enrolled, we compared laboratory diagnoses to their partner's perception of their status. Black MSM who perceived themselves to be HIV negative were more likely than perceived-negative white MSM to have a positive partner among those they perceived to be HIV negative or whose status was unknown to them (OR=6.6). Furthermore, although frequency of unprotected anal intercourse (UAI) was similar by race, black men were more likely to have had UAI with an unknown-positive partner (OR=9.3).

  5. A Study of the Role of Clouds in the Relationship Between Land Use/Land Cover and the Climate and Air Quality of the Atlanta Area

    NASA Technical Reports Server (NTRS)

    Kidder, Stanley Q.; Hafner, Jan

    1997-01-01

    The goal of Project ATLANTA is to derive a better scientific understanding of how land cover changes associated with urbanization affect local and regional climate and air quality. Clouds play a significant role in this relationship. Using GOES images, we found that in a 63-day period (5 July-5 September 1996) there were zero days which were clear for the entire daylight period. Days which are cloud-free in the morning become partly cloudy with small cumulus clouds in the afternoon in response to solar heating. This result casts doubt on the applicability of California-style air quality models which run in perpetual clear skies. Days which are clear in the morning have higher ozone than those which are cloudy in the morning. Using the RAMS model, we found that urbanization increases the skin surface temperature by about 1.0-1.5 C on average under cloudy conditions, with an extreme of +3.5 C. Clouds cool the surface due to their shading effect by 1.5-2.0 C on average, with an extreme of 5.0 C. RAMS simulates well the building stage of the cumulus cloud field, but does poorly in the decaying phase. Next year's work: doing a detailed cloud climatology and developing improved RAMS cloud simulations.

  6. Process dependency on threshold voltage of GaN MOSFET on AlGaN/GaN heterostructure

    NASA Astrophysics Data System (ADS)

    Wang, Qingpeng; Jiang, Ying; Miyashita, Takahiro; Motoyama, Shin-ichi; Li, Liuan; Wang, Dejun; Ohno, Yasuo; Ao, Jin-Ping

    2014-09-01

    GaN metal-oxide-semiconductor field-effect transistors (MOSFETs) with recessed gate on AlGaN/GaN heterostructure are reported in which the drain and source ohmic contacts were fabricated on the AlGaN/GaN heterostructure and the electron channel was formed on the GaN buffer layer by removing the AlGaN barrier layer. Negative threshold voltages were commonly observed in all devices. To investigate the reasons of the negative threshold voltages, different oxide thickness, etching gas and bias power of inductively-coupled plasma (ICP) system were utilized in the fabrication process of the GaN MOSFETs. It is found that positive charges of around 1 × 1012 q/cm2 exist near the interface at the just threshold condition in both silane- and tetraethylorthosilicate (TEOS)-based devices. It is also found that the threshold voltages do not obviously change with the different etching gas (SiCl4, BCl3 and two-step etching of SiCl4/Cl2) at the same ICP bias power level (20-25 W) and will become deeper when higher bias power is used in the dry recess process which may be related to the much serious ion bombardment damage. Furthermore, X-ray photoelectron spectroscopy (XPS) experiments were done to investigate the surface conditions. It is found that N 1s peaks become lower with higher bias power of the dry etching process. Also, silicon contamination was found and could be removed by HNO3/HF solution. It indicates that the nitrogen vacancies are mainly responsible for the negative threshold voltages rather than the silicon contamination. It demonstrates that optimization of the ICP recess conditions and improvement of the surface condition are still necessary to realize enhancement-mode GaN MOSFETs on AlGaN/GaN heterostructure.

  7. Asymmetric quantum-well structures for AlGaN/GaN/AlGaN resonant tunneling diodes

    NASA Astrophysics Data System (ADS)

    Yang, Lin'an; Li, Yue; Wang, Ying; Xu, Shengrui; Hao, Yue

    2016-04-01

    Asymmetric quantum-well (QW) structures including the asymmetric potential-barrier and the asymmetric potential-well are proposed for AlGaN/GaN/AlGaN resonant tunneling diodes (RTDs). Theoretical investigation gives that an appropriate decrease in Al composition and thickness for emitter barrier as well as an appropriate increase of both for collector barrier can evidently improve the negative-differential-resistance characteristic of RTD. Numerical simulation shows that RTD with a 1.5-nm-thick GaN well sandwiched by a 1.3-nm-thick Al0.15Ga0.85N emitter barrier and a 1.7-nm-thick Al0.25Ga0.75N collector barrier can yield the I-V characteristic having the peak current (Ip) and the peak-to-valley current ratio (PVCR) of 0.39 A and 3.6, respectively, about double that of RTD with a 1.5-nm-thick Al0.2Ga0.8N for both barriers. It is also found that an introduction of InGaN sub-QW into the diode can change the tunneling mode and achieve higher transmission coefficient of electron. The simulation demonstrates that RTD with a 2.8-nm-thick In0.03Ga0.97N sub-well in front of a 2.0-nm-thick GaN main-well can exhibit the I-V characteristic having Ip and PVCR of 0.07 A and 11.6, about 7 times and double the value of RTD without sub-QW, respectively. The purpose of improving the structure of GaN-based QW is to solve apparent contradiction between the device structure and the device manufacturability of new generation RTDs for sub-millimeter and terahertz applications.

  8. 46 CFR 2.10-20 - General requirements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ....O. Box 531030, Atlanta, GA 30353-1030. (iii) For payment by check, made payable to U.S. Treasury... (COI), 1075 Loop Road, Atlanta, GA 30337-6002. (2) For Overseas Inspection Fees: (i) For payment by... 531769, Atlanta, GA 30353-1769. (iii) For payment by check, made payable to U.S. Treasury, with...

  9. 46 CFR 2.10-20 - General requirements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ....O. Box 531030, Atlanta, GA 30353-1030. (iii) For payment by check, made payable to U.S. Treasury... (COI), 1075 Loop Road, Atlanta, GA 30337-6002. (2) For Overseas Inspection Fees: (i) For payment by... 531769, Atlanta, GA 30353-1769. (iii) For payment by check, made payable to U.S. Treasury, with...

  10. 46 CFR 2.10-20 - General requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ....O. Box 531030, Atlanta, GA 30353-1030. (iii) For payment by check, made payable to U.S. Treasury... (COI), 1075 Loop Road, Atlanta, GA 30337-6002. (2) For Overseas Inspection Fees: (i) For payment by... 531769, Atlanta, GA 30353-1769. (iii) For payment by check, made payable to U.S. Treasury, with...

  11. 46 CFR 2.10-20 - General requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Inspection Fees, P.O. Box 531030, Atlanta, GA 30353-1030. (iii) For payment by check, made payable to U.S... 531030 (COI), 1075 Loop Road, Atlanta, GA 30337-6002. (2) For Overseas Inspection Fees: (i) For payment..., P.O. Box 531769, Atlanta, GA 30353-1769. (iii) For payment by check, made payable to U.S....

  12. 75 FR 56652 - Supplemental Draft Environmental Impact Statement (SDEIS) for Northwest I-75/I-575 Corridor, Cobb...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-16

    ...-75/I-575 Corridor, Cobb and Cherokee Counties, GA (Atlanta Metropolitan Area) AGENCY: Federal Highway... Department of Transportation, 600 West Peachtree Street, NW., One Georgia Center, 27th Floor, Atlanta, GA... Engineer, 600 West Peachtree Street, NW., One Georgia Center, 27th Floor, Atlanta, GA 30308....

  13. GaN-based ultraviolet light-emitting diodes with AlN/GaN/InGaN multiple quantum wells.

    PubMed

    Chang, Hung-Ming; Lai, Wei-Chih; Chen, Wei-Shou; Chang, Shoou-Jinn

    2015-04-01

    We demonstrate indium gallium nitride/gallium nitride/aluminum nitride (AlN/GaN/InGaN) multi-quantum-well (MQW) ultraviolet (UV) light-emitting diodes (LEDs) to improve light output power. Similar to conventional UV LEDs with AlGaN/InGaN MQWs, UV LEDs with AlN/GaN/InGaN MQWs have forward voltages (V(f)'s) ranging from 3.21 V to 3.29 V at 350 mA. Each emission peak wavelength of AlN/GaN/InGaN MQW UV LEDs presents 350 mA output power greater than that of the corresponding emission peak wavelength of AlGaN/InGaN MQW UV LEDs. The light output power at 350mA of AlN/GaN/InGaN MQWs UV LEDs with 375 nm emission wavelength can reach around 26.7% light output power enhancement in magnitude compared to the AlGaN/InGaN MQWs UV LEDs with same emission wavelength. But 350mA light output power of AlN/GaN/InGaN MQWs UV LEDs with emission wavelength of 395nm could only have light output power enhancement of 2.43% in magnitude compared with the same emission wavelength AlGaN/InGaN MQWs UV LEDs. Moreover, AlN/GaN/InGaN MQWs present better InGaN thickness uniformity, well/barrier interface quality and less large size pits than AlGaN/InGaN MQWs, causing AlN/GaN/InGaN MQW UV LEDs to have less reverse leakage currents at -20 V. Furthermore, AlN/GaN/InGaN MQW UV LEDs have the 2-kV human body mode (HBM) electrostatic discharge (ESD) pass yield of 85%, which is 15% more than the 2-kV HBM ESD pass yield of AlGaN/InGaN MQW UV LEDs of 70%.

  14. 78 FR 33799 - National Poultry Improvement Plan; General Conference Committee Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-05

    ... Animal and Plant Health Inspection Service National Poultry Improvement Plan; General Conference.... SUMMARY: We are giving notice of a meeting of the General Conference Committee of the National Poultry... Poultry Improvement Plan, VS, APHIS, 1506 Klondike Road, Suite 101, Conyers, GA 30094; (770)...

  15. InGaN light-emitting diodes with embedded nanoporous GaN distributed Bragg reflectors

    NASA Astrophysics Data System (ADS)

    Shieh, Bing-Cheng; Jhang, Yuan-Chang; Huang, Kun-Pin; Huang, Wan-Chun; Dai, Jing-Jie; Lai, Chun-Feng; Lin, Chia-Feng

    2015-08-01

    InGaN-based light-emitting diodes (LEDs) with embedded conductive nanoporous GaN/undoped GaN (NP-GaN/u-GaN) distributed Bragg reflectors (DBRs) were demonstrated. Nanoporous GaN DBR structures were fabricated by pulsed 355 nm laser scribing and electrochemical etching processes. Heavily Si-doped n-type GaN:Si layers (n+-GaN) in an eight-period n+-GaN/u-GaN stack structure were transformed into a low-refractive-index, conductive nanoporous GaN structure. The measured center wavelength, peak reflectivity, and bandwidth of the nanoporous GaN DBR structure were 417 nm, 96.7%, and 34 nm, respectively. Resonance cavity modes of the photoluminescence spectra were observed in the treated LED structure with the nanoporous DBR structure.

  16. Reliability comparison of GaAlAs/GaAs and aluminum-free high-power laser diodes

    NASA Astrophysics Data System (ADS)

    Pendse, D. R.; Chin, Aland K.; Dabkowski, Ferdynand P.; Clausen, Edward M., Jr.

    1998-08-01

    Aluminum-free laser diodes are InGaAsP/GaAs devices whose epitaxial layers do not contain aluminum. Studies comparing the GaAslAs/GaAs and InGaAsP/GaAs high power laser diodes allegedly indicate that aluminum-free lasers are more reliable due to a reduction of dark-line defects, sudden failures, and gradual degradation. The improved reliability of aluminum-free lasers is presumed to result from the elimination of oxidation of the aluminum-containing epitaxial layers of the laser facets. In this presentation, the performance and reliability of GaAlAs/GaAs and InGaAsP/GaAs high power laser diodes will be reviewed and compared. The present data shows that high reliable GaAlAs/GaAs lasers can be produced with good manufacturing practices.

  17. Normally-off p-GaN/AlGaN/GaN high electron mobility transistors using hydrogen plasma treatment

    NASA Astrophysics Data System (ADS)

    Hao, Ronghui; Fu, Kai; Yu, Guohao; Li, Weiyi; Yuan, Jie; Song, Liang; Zhang, Zhili; Sun, Shichuang; Li, Xiajun; Cai, Yong; Zhang, Xinping; Zhang, Baoshun

    2016-10-01

    In this letter, we report a method by introducing hydrogen plasma treatment to realize normally-off p-GaN/AlGaN/GaN HEMT devices. Instead of using etching technology, hydrogen plasma was adopted to compensate holes in the p-GaN above the two dimensional electron gas (2DEG) channel to release electrons in the 2DEG channel and form high-resistivity area to reduce leakage current and increase gate control capability. The fabricated p-GaN/AlGaN/GaN HEMT exhibits normally-off operation with a threshold voltage of 1.75 V, a subthreshold swing of 90 mV/dec, a maximum transconductance of 73.1 mS/mm, an ON/OFF ratio of 1 × 107, a breakdown voltage of 393 V, and a maximum drain current density of 188 mA/mm at a gate bias of 6 V. The comparison of the two processes of hydrogen plasma treatment and p-GaN etching has also been made in this work.

  18. GaInP/GaAs/GaInAs Monolithic Tandem Cells for High-Performance Solar Concentrators

    SciTech Connect

    Wanlass, M. W.; Ahrenkiel, S. P.; Albin, D. S.; Carapella, J. J.; Duda, A.; Emery, K.; Geisz, J. F.; Jones, K.; Kurtz, S.; Moriarty, T.; Romero, M. J.

    2005-08-01

    We present a new approach for ultra-high-performance tandem solar cells that involves inverted epitaxial growth and ultra-thin device processing. The additional degree of freedom afforded by the inverted design allows the monolithic integration of high-, and medium-bandgap, lattice-matched (LM) subcell materials with lower-bandgap, lattice-mismatched (LMM) materials in a tandem structure through the use of transparent compositionally graded layers. The current work concerns an inverted, series-connected, triple-bandgap, GaInP (LM, 1.87 eV)/GaAs (LM, 1.42 eV)/GaInAs (LMM, {approx}1 eV) device structure grown on a GaAs substrate. Ultra-thin tandem devices are fabricated by mounting the epiwafers to pre-metallized Si wafer handles and selectively removing the parent GaAs substrate. The resulting handle-mounted, ultra-thin tandem cells have a number of important advantages, including improved performance and potential reclamation/reuse of the parent substrate for epitaxial growth. Additionally, realistic performance modeling calculations suggest that terrestrial concentrator efficiencies in the range of 40-45% are possible with this new tandem cell approach. A laboratory-scale (0.24 cm2), prototype GaInP/GaAs/GaInAs tandem cell with a terrestrial concentrator efficiency of 37.9% at a low concentration ratio (10.1 suns) is described, which surpasses the previous world efficiency record of 37.3%.

  19. Impact ionization in N-polar AlGaN/GaN high electron mobility transistors

    SciTech Connect

    Killat, N. E-mail: Martin.Kuball@bristol.ac.uk; Uren, M. J.; Kuball, M. E-mail: Martin.Kuball@bristol.ac.uk; Keller, S.; Kolluri, S.; Mishra, U. K.

    2014-08-11

    The existence of impact ionization as one of the open questions for GaN device reliability was studied in N-polar AlGaN/GaN high electron mobility transistors. Electroluminescence (EL) imaging and spectroscopy from underneath the device gate contact revealed the presence of hot electrons in excess of the GaN bandgap energy even at moderate on-state bias conditions, enabling impact ionization with hole currents up to several hundreds of pA/mm. The detection of high energy luminescence from hot electrons demonstrates that EL analysis is a highly sensitive tool to study degradation mechanisms in GaN devices.

  20. In(x)Ga(1-x)As/GaAs Quantum-Well Infrared Photodetectors

    NASA Technical Reports Server (NTRS)

    Gunapala, Sarath D.; Park, Jin S.; Lin, True-Lon; Liu, John K.

    1995-01-01

    Choice of materials for present quantum-well infrared photodetectors (QWIPs) affected principally by two considerations. One was that in comparison with GaAs, In(x)Ga(1-x)As is potentially superior quantum-well material because of its stronger absorption of infrared radiation. Other consideration was that in comparison with Al(x)Ga(1-x)As, which is usual barrier material in older devices, GaAs potentially superior barrier material because it exhibits superior transport properties (lower scattering and higher mobility of charge carriers). GaAs is well material in older devices and barrier material in present devices.

  1. AlGaN/GaN HEMT And ZnO nanorod-based sensors for chemical and bio-applications

    NASA Astrophysics Data System (ADS)

    Chu, B. H.; Kang, B. S.; Wang, H. T.; Chang, C. Y.; Lele, T.,; Tseng, Y.; Goh, A.; Sciullo, A.; Wu, W. S.; Lin, J. N.; Gila, B. P.; Pearton, S. J.; Johnson, J. W.; Piner, E. L.; Linthicum, K. J.; Ren, F.

    2009-02-01

    Chemical sensors can be used to analyze a wide variety of environmental and biological gases and liquids and may need to be able to selectively detect a target analyte. Different methods, including gas chromatography (GC), chemiluminescence, selected ion flow tube (SIFT), and mass spectroscopy (MS) have been used to measure biomarkers. These methods show variable results in terms of sensitivity for some applications and may not meet the requirements for a handheld biosensor. A promising sensing technology utilizes AlGaN/GaN high electron mobility transistors (HEMTs). HEMT structures have been developed for use in microwave power amplifiers due to their high two dimensional electron gas (2DEG) mobility and saturation velocity. The conducting 2DEG channel of GaN/AlGaN HEMTs is very close to the surface and extremely sensitive to adsorption of analytes. HEMT sensors can be used for detecting gases, ions, pH values, proteins, and DNA. In this paper we review recent progress on functionalizing the surface of HEMTs for specific detection of glucose, kidney marker injury molecules, prostate cancer and other common substances of interest in the biomedical field.

  2. Room temperature plasmonic lasing in a continuous wave operation mode from an InGaN/GaN single nanorod with a low threshold

    PubMed Central

    Hou, Y.; Renwick, P.; Liu, B.; Bai, J.; Wang, T.

    2014-01-01

    It is crucial to fabricate nano photonic devices such as nanolasers in order to meet the requirements for the integration of photonic and electronic circuits on the nanometre scale. The great difficulty is to break down a bottleneck as a result of the diffraction limit of light. Nanolasers on a subwavelength scale could potentially be fabricated based on the principle of surface plasmon amplification by stimulated emission of radiation (SPASER). However, a number of technological challenges will have to be overcome in order to achieve a SPASER with a low threshold, allowing for a continuous wave (cw) operation at room temperature. We report a nano-SPASER with a record low threshold at room temperature, optically pumped by using a cw diode laser. Our nano-SPASER consists of a single InGaN/GaN nanorod on a thin SiO2 spacer layer on a silver film. The nanorod containing InGaN/GaN multi-quantum-wells is fabricated by means of a cost-effective post-growth fabrication approach. The geometry of the nanorod/dielectric spacer/plasmonic metal composite allows us to have accurate control of the surface plasmon coupling, offering an opportunity to determine the optimal thickness of the dielectric spacer. This approach will open up a route for further fabrication of electrically injected plasmonic lasers. PMID:24852881

  3. Identification of photoluminescence bands in AlGaAs/InGaAs/GaAs PHEMT heterostructures with donor-acceptor-doped barriers

    SciTech Connect

    Gulyaev, D. V. Zhuravlev, K. S.; Bakarov, A. K.; Toropov, A. I.

    2015-02-15

    The photoluminescence of AlGaAs/InGaAs/GaAs pseudomorphic high-electron mobility transistor heterostructures with donor-acceptor-doped AlGaAs barriers is studied. It is found that the introduction of additional p{sup +}-doped AlGaAs layers into the design brings about the appearance of new bands in the photoluminescence spectra. These bands are identified as resulting from transitions (i) in donor-acceptor pairs in doped AlGaAs layers and (ii) between the conduction subband and acceptor levels in the undoped InGaAs quantum well.

  4. TEM Characterization of InAs/GaAs Quantum Dots Capped by a GaSb/GaAs Layer

    SciTech Connect

    Beltran, AM; Ben, Teresa; Sanchez, AM; Sales Lerida, David; Chisholm, Matthew F; Varela del Arco, Maria; Pennycook, Stephen J; Galindo, Pedro; Ripalda, JM; Molina Rubio, Sergio I

    2008-01-01

    It is well known that there is intense interest in expanding the usable wavelength for electronic devices. This is one of the reasons to study new self-assembled semiconductor nanostructures. Telecommunication applications use InGaAsP/InP emitting at 1.3 and 1.55 m. Research efforts are dedicated to develop GaAs technology in order to achieve emission at the same range as InP, so GaAs could be used for optical fibre communications. Ga(As)Sb on InAs/GaAs quantum dots (QDs) is a promising nanostructure to be used in telecommunications. The introduction of antimony during or after the QDs growth is an effective solution to obtain a red shift in the emission wavelength, even at room temperature.

  5. Highly efficient pseudomorphic InGaAs/GaAs/AlGaAs single quantum well lasers for monolithic integration

    NASA Technical Reports Server (NTRS)

    Larsson, A.; Cody, J.; Forouhar, S.; Lang, R. J.

    1990-01-01

    Highly efficient ridge waveguide pseudomorphic single quantum well lasers, emitting at 980 nm, have been fabricated from an In(0.2)Ga(0.8)As/GaAs/AlGaAs graded-index separate confinement heterostructure grown by molecular beam epitaxy. The laterial index guiding provided by the ridge reduces the anomalously large lateral loss of optical power found in gain-guided structures, thereby reducing the internal loss by more than 50 percent. The low threshold current (7.6 mA) and high differential quantum efficiency (79 percent) obtained under continuous operation as well as the transparency of the GaAs substrate to the emitted radiation render these lasers attractive for Ga-As-based optoelectronic integration.

  6. Fine structure of Fe-Co-Ga and Fe-Cr-Ga alloys with low Ga content

    SciTech Connect

    Kleinerman, Nadezhda M. Serikov, Vadim V. Vershinin, Aleksandr V. Mushnikov, Nikolai V. Stashkova, Liudmila A.

    2014-10-27

    Investigation of Ga influence on the structure of Fe-Cr and Fe-Co alloys was performed with the use of {sup 57}Fe Mössbauer spectroscopy and X-ray diffraction methods. In the alloys of the Fe-Cr system, doping with Ga handicaps the decomposition of solid solutions, observed in the binary alloys, and increases its stability. In the alloys with Co, Ga also favors the uniformity of solid solutions. The analysis of Mössbauer experiments gives some grounds to conclude that if, owing to liquation, clusterization, or initial stages of phase separation, there exist regions enriched in iron, some amount of Ga atoms prefer to enter the nearest surroundings of iron atoms, thus forming binary Fe-Ga regions (or phases)

  7. Photoreflectance spectroscopy of step-like GaInNAs/GaInNAs/GaAs quantum wells

    NASA Astrophysics Data System (ADS)

    Kudrawiec, R.; Andrzejewski, J.; Misiewicz, J.; Gollub, D.; Forchel, A.

    2005-05-01

    Photoreflectance (PR) spectroscopy has been applied to study of step-like GaInNAs/GaInNAs/GaAs double quantum well (DQW) structures grown by molecular beam epitaxy. PR features related to optical transitions in the active part of the step-like QW structure, i.e. GaInNAs/GaInNAs QW, as well as PR features related to transitions above the step-like barrier (SLB) have been clearly observed and analysed in this paper. The analysis of the QW transitions gives information about the number of confined states in the active part of the step-like QW structure. In addition, the analysis of the second portion of PR signal gives information about the band gap energy of the SLB and optical transitions between hole and electron levels confined above the SLB.

  8. Effect of GaAs native oxide upon the surface morphology during GaAs MBE growth

    NASA Astrophysics Data System (ADS)

    Ageev, O. A.; Solodovnik, M. S.; Balakirev, S. V.; Mikhaylin, I. A.; Eremenko, M. M.

    2016-08-01

    The GaAs native oxide effect upon the surface morphology of the GaAs epitaxial layer was studied with taking into account the main growth parameters of MBE technology: substrate temperature, effective As4/Ga flux ratio and growth rate. The MBE modes of atomically smooth and rough surfaces and surfaces with Ga droplet array formation were determined. The possibility of the obtaining of GaAs nanowires via GaAs native oxide layer was shown.

  9. AlGaN/InGaN Photocathode Development

    SciTech Connect

    Buckley, J. H.; Leopold, D. J.

    2008-12-24

    An increase in quantum efficiency in photodetectors could result in a proportional reduction in the area of atmospheric Cherenkov telescopes and an even larger reduction in cost. We report on the development of high quantum efficiency, high gain, UV/blue photon-counting detectors based on AlGaN/InGaN photocathode heterostructures grown by molecular beam epitaxy. This research could eventually result in nearly ideal light detectors with a number of distinct advantages over existing technologies for numerous applications in high-energy physics and particle astrophysics. Potential advantages include much lower noise detection, better stability and radiation resistance than other cathode structures, high VUV sensitivity and very low radioactive background levels for deep underground experiments, and high detection efficiency for the detection of individual VUV-visible photons. We are also developing photocathodes with intrinsic gain, initially improving the detection efficiency of hybrid semiconductor-vacuum tube devices and eventually leading to a new type of all-solid-state photomultiplier device.

  10. Self-diffusion in 69Ga121Sb/71Ga123Sb isotope heterostructures

    NASA Astrophysics Data System (ADS)

    Bracht, H.; Nicols, S. P.; Haller, E. E.; Silveira, J. P.; Briones, F.

    2001-05-01

    Gallium and antimony self-diffusion experiments have been performed in undoped 69Ga121Sb/71Ga123Sb isotope heterostructures at temperatures between 571 and 708 °C under Sb- and Ga-rich ambients. Ga and Sb profiles measured with secondary ion mass spectrometry reveal that Ga diffuses faster than Sb by several orders of magnitude. This strongly suggests that the two self-atom species diffuse independently on their own sublattices. Experimental results lead us to conclude that Ga and Sb diffusion are mediated by Ga vacancies and Sb interstitials, respectively, and not by the formation of a triple defect proposed earlier by Weiler and Mehrer [Philos. Mag. A 49, 309 (1984)]. The extremely slow diffusion of Sb up to the melting temperature of GaSb is proposed to be a consequence of amphoteric transformations between native point defects which suppress the formation of those native defects which control Sb diffusion. Preliminary experiments exploring the effect of Zn indiffusion at 550 °C on Ga and Sb diffusion reveal an enhanced intermixing of the Ga isotope layers compared to undoped GaSb. However, under the same conditions the diffusion of Sb was not significantly affected.

  11. A hole modulator for InGaN/GaN light-emitting diodes

    SciTech Connect

    Zhang, Zi-Hui; Kyaw, Zabu; Liu, Wei; Ji, Yun; Wang, Liancheng; Tan, Swee Tiam; Sun, Xiao Wei E-mail: VOLKAN@stanfordalumni.org; Demir, Hilmi Volkan E-mail: VOLKAN@stanfordalumni.org

    2015-02-09

    The low p-type doping efficiency of the p-GaN layer has severely limited the performance of InGaN/GaN light-emitting diodes (LEDs) due to the ineffective hole injection into the InGaN/GaN multiple quantum well (MQW) active region. The essence of improving the hole injection efficiency is to increase the hole concentration in the p-GaN layer. Therefore, in this work, we have proposed a hole modulator and studied it both theoretically and experimentally. In the hole modulator, the holes in a remote p-type doped layer are depleted by the built-in electric field and stored in the p-GaN layer. By this means, the overall hole concentration in the p-GaN layer can be enhanced. Furthermore, the hole modulator is adopted in the InGaN/GaN LEDs, which reduces the effective valance band barrier height for the p-type electron blocking layer from ∼332 meV to ∼294 meV at 80 A/cm{sup 2} and demonstrates an improved optical performance, thanks to the increased hole concentration in the p-GaN layer and thus the improved hole injection into the MQWs.

  12. Anelasticity of GaN Epitaxial Layer in GaN LED

    NASA Astrophysics Data System (ADS)

    Chung, C. C.; Yang, C. T.; Liu, C. Y.

    2016-10-01

    In this work, the anelasticity of the GaN layer in the GaN light-emitting-diode device was studied. The present results show that the forward-voltage of GaN LED increases with time, as the GaN light-emitting-diode was maintained at a constant temperature of 100 °C. We found that the increase of the forward-voltage with time attributes to the delay-response of the piezoelectric fields (internal electrical fields in GaN LED device). And, the delay-response of the internal electrical fields with time is caused by the anelasticity (time-dependent strain) of the GaN layer. Therefore, using the correlation of strain-piezoelectric-forward voltage, a plot of thermal strain of the GaN layer against time can be obtained by measuring the forward-voltage of the studied GaN LED against time. With the curves of the thermal strain of GaN epi-layers versus time, the anelasticity of the GaN compound can be studied. The key anelasticity parameter, characteristic relaxation time, of the GaN is defined to be 2623.76 min in this work.

  13. Working toward high-power GaN/InGaN heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    Shen, Shyh-Chiang; Dupuis, Russell D.; Lochner, Zachery; Lee, Yi-Che; Kao, Tsung-Ting; Zhang, Yun; Kim, Hee-Jin; Ryou, Jae-Hyun

    2013-07-01

    III-nitride (III-N) heterojunction bipolar transistors (HBTs) are a less-explored electronic device technology due to the myriad research issues in material growth, device design and fabrication associated with these devices. For III-N HBTs, npn-GaN/InGaN heterostructures provide the benefits of mitigating the poor base electrical conductivity of p-type GaN and the problematic magnesium incorporation issues. Consequently, InGaN-base III-N HBTs are promising for next-generation high-power RF III-N systems. This paper will describe the current development status of npn GaN/InGaN HBTs grown either on sapphire or free-standing (FS) GaN substrates using optimized metalorganic chemical vapor deposition (MOCVD) and refined HBT processing techniques. Recombination current paths in GaN/InGaN HBTs are studied and small-signal equivalent circuits are developed. The extracted device model indicates that, with further device fabrication technique development, Johnson's figure of merit (JFOM) of GaN/InGaN HBTs can be as high as 5 THz V.

  14. Multicharacterization approach for studying InAl(Ga)N/Al(Ga)N/GaN heterostructures for high electron mobility transistors

    SciTech Connect

    Naresh-Kumar, G. Trager-Cowan, C.; Vilalta-Clemente, A.; Morales, M.; Ruterana, P.; Pandey, S.; Cavallini, A.; Cavalcoli, D.; Skuridina, D.; Vogt, P.; Kneissl, M.; Behmenburg, H.; Giesen, C.; Heuken, M.; Gamarra, P.; Di Forte-Poisson, M. A.; Patriarche, G.; Vickridge, I.

    2014-12-15

    We report on our multi–pronged approach to understand the structural and electrical properties of an InAl(Ga)N(33nm barrier)/Al(Ga)N(1nm interlayer)/GaN(3μm)/ AlN(100nm)/Al{sub 2}O{sub 3} high electron mobility transistor (HEMT) heterostructure grown by metal organic vapor phase epitaxy (MOVPE). In particular we reveal and discuss the role of unintentional Ga incorporation in the barrier and also in the interlayer. The observation of unintentional Ga incorporation by using energy dispersive X–ray spectroscopy analysis in a scanning transmission electron microscope is supported with results obtained for samples with a range of AlN interlayer thicknesses grown under both the showerhead as well as the horizontal type MOVPE reactors. Poisson–Schrödinger simulations show that for high Ga incorporation in the Al(Ga)N interlayer, an additional triangular well with very small depth may be exhibited in parallel to the main 2–DEG channel. The presence of this additional channel may cause parasitic conduction and severe issues in device characteristics and processing. Producing a HEMT structure with InAlGaN as the barrier and AlGaN as the interlayer with appropriate alloy composition may be a possible route to optimization, as it might be difficult to avoid Ga incorporation while continuously depositing the layers using the MOVPE growth method. Our present work shows the necessity of a multicharacterization approach to correlate structural and electrical properties to understand device structures and their performance.

  15. Color tunable monolithic InGaN/GaN LED having a multi-junction structure.

    PubMed

    Kong, Duk-Jo; Kang, Chang-Mo; Lee, Jun-Yeob; Kim, James; Lee, Dong-Seon

    2016-03-21

    In this study, we have fabricated a blue-green color-tunable monolithic InGaN/GaN LED having a multi-junction structure with three terminals. The device has an n-p-n structure consisting of a green and a blue active region, i.e., an n-GaN / blue-MQW / p-GaN / green-MQW / n-GaN / Al2O3 structure with three terminals for independently controlling the two active regions. To realize this LED structure, a typical LED consisting of layers of n-GaN, blue MQW, and p-GaN is regrown on a conventional green LED by using a metal organic chemical vapor deposition (MOCVD) method. We explain detailed mechanisms of three operation modes which are the green, blue, and cyan mode. Moreover, we discuss optical properties of the device. PMID:27136884

  16. Effect of dislocation density on thermal boundary conductance across GaSb/GaAs interfaces

    SciTech Connect

    Hopkins, Patrick E.; Duda, John C.; Clark, Stephen P.; Hains, Christopher P.; Rotter, Thomas J.; Balakrishnan, Ganesh; Phinney, Leslie M.

    2011-04-18

    We report on the thermal boundary conductance across structurally-variant GaSb/GaAs interfaces characterized by different dislocations densities, as well as variably-rough Al/GaSb interfaces. The GaSb/GaAs structures are epitaxially grown using both interfacial misfit (IMF) and non-IMF techniques. We measure the thermal boundary conductance from 100 to 450 K with time-domain thermoreflectance. The thermal boundary conductance across the GaSb/GaAs interfaces decreases with increasing strain dislocation density. We develop a model for interfacial transport at structurally-variant interfaces in which phonon propagation and scattering parallels photon attenuation. We find that this model describes the measured thermal boundary conductances well.

  17. Color tunable monolithic InGaN/GaN LED having a multi-junction structure.

    PubMed

    Kong, Duk-Jo; Kang, Chang-Mo; Lee, Jun-Yeob; Kim, James; Lee, Dong-Seon

    2016-03-21

    In this study, we have fabricated a blue-green color-tunable monolithic InGaN/GaN LED having a multi-junction structure with three terminals. The device has an n-p-n structure consisting of a green and a blue active region, i.e., an n-GaN / blue-MQW / p-GaN / green-MQW / n-GaN / Al2O3 structure with three terminals for independently controlling the two active regions. To realize this LED structure, a typical LED consisting of layers of n-GaN, blue MQW, and p-GaN is regrown on a conventional green LED by using a metal organic chemical vapor deposition (MOCVD) method. We explain detailed mechanisms of three operation modes which are the green, blue, and cyan mode. Moreover, we discuss optical properties of the device.

  18. AlGaN/GaN heterostructure prepared on a Si (110) substrate via pulsed sputtering

    SciTech Connect

    Watanabe, T.; Ohta, J.; Kondo, T.; Ohashi, M.; Ueno, K.; Kobayashi, A.; Fujioka, H.

    2014-05-05

    GaN films were grown on Si (110) substrates using a low-temperature growth technique based on pulsed sputtering. Reduction of the growth temperature suppressed the strain in the GaN films, leading to an increase in the critical thickness for crack formation. In addition, an AlGaN/GaN heterostructure with a flat heterointerface was prepared using this technique. Furthermore, the existence of a two dimensional electron gas at the heterointerface with a mobility of 1360 cm{sup 2}/Vs and a sheet carrier density of 1.3 × 10{sup 13} cm{sup −2} was confirmed. Finally, the use of the AlGaN/GaN heterostructure in a high electron mobility transistor was demonstrated. These results indicate that low-temperature growth via pulsed sputtering is quite promising for the fabrication of GaN-based electronic devices.

  19. Red-emitting Ga/As,P///In,Ga/P heterojunction lasers

    NASA Technical Reports Server (NTRS)

    Kressel, H.; Nuese, C. J.; Olsen, G. H.

    1978-01-01

    The paper describes in detail the properties of vapor-grown double-heterojunction lasers of Ga(As,P)/(In,Ga)P with room-temperature threshold current densities as low as 3400 A/sq cm at 7000 A and 6600 A/sq cm at 6800 A. These thresholds are three to eight times smaller than those of (Al,Ga)As lasers in this wavelength range due to the shorter-wavelength direct-indirect transition in Ga(As,P). The optical and electrical characteristics of the Ga(As,P)/(In,Ga)P lasers are found to be similar to those of (Al,Ga)As, with fundamental transverse-mode operation to 70 C, and spontaneous carrier lifetimes between 5 and 8 nsec typically observed at low current densities.

  20. Microwave performance of a self-aligned GaInP/Ga heterojunction bipolar transistor

    SciTech Connect

    Liu, W.; Fan, Shoukong; Henderson, T. ); Davito, D. )

    1993-04-01

    Microwave performance of a self-aligned GaInP/GaAs heterojunction bipolar transistor (HBT) is presented. At an operating current density of 2.08 [times] 10[sup 4] A/cm[sup 2], the measured cutoff frequency is 50 GHz, and the maximum oscillation frequency extrapolated from measured unilateral gain and the maximum available gain are 116 and 81 GHz, respectively, all using 20-dB/decade slopes. To the author's knowledge, these represent the highest reported values of HBT's based on the GaInP/GaAs material system. These results are compared with other reported high-frequency performance of GaInP HBT's. In addition, these results are compared with AlGaAs/GaAs HBT's having a similar device structure.

  1. 78 FR 38009 - Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-25

    ... ] Public Comment, Open Topics All meetings are accessible to persons with disabilities. An assistive listening system, Communication Access Realtime Translation (CART), and sign language interpreters will...

  2. Metal-interconnection-free integration of InGaN/GaN light emitting diodes with AlGaN/GaN high electron mobility transistors

    SciTech Connect

    Liu, Chao; Cai, Yuefei; Liu, Zhaojun; Ma, Jun; Lau, Kei May

    2015-05-04

    We report a metal-interconnection-free integration scheme for InGaN/GaN light emitting diodes (LEDs) and AlGaN/GaN high electron mobility transistors (HEMTs) by combining selective epi removal (SER) and selective epitaxial growth (SEG) techniques. SER of HEMT epi was carried out first to expose the bottom unintentionally doped GaN buffer and the sidewall GaN channel. A LED structure was regrown in the SER region with the bottom n-type GaN layer (n-electrode of the LED) connected to the HEMTs laterally, enabling monolithic integration of the HEMTs and LEDs (HEMT-LED) without metal-interconnection. In addition to saving substrate real estate, minimal interface resistance between the regrown n-type GaN and the HEMT channel is a significant improvement over metal-interconnection. Furthermore, excellent off-state leakage characteristics of the driving transistor can also be guaranteed in such an integration scheme.

  3. Ultrafast Exciton Dynamics in InGaN/GaN and Rh/Cr2O3 Nanoparticle-Decorated InGaN/GaN Nanowires.

    PubMed

    Pu, Ying-Chih; Kibria, M G; Mi, Zetian; Zhang, Jin Z

    2015-07-01

    Ultrafast exciton and charge-carrier dynamics in InGaN/GaN nanowires (NWs) with and without Rh/Cr2O3 nanoparticle (NP) decoration have been investigated using femtosecond transient absorption (TA) techniques with excitation at 415 nm and white-light probe (450-700 nm). By comparing the TA profiles between InGaN/GaN and InGaN/GaN-Rh/Cr2O3 NWs, an additional decay component on the medium time scale (∼50 ps) was identified with Rh/Cr2O3 decoration, which is attributed to interfacial charge transfer from InGaN/GaN NWs to Rh/Cr2O3 NPs, desired for light energy conversion applications. This is consistent with reduced photoluminescence (PL) of the NWs by the Rh/Cr2O3 NPs. A kinetic model was developed to explain the TA results and gain further insight into the exciton and charge-carrier dynamics.

  4. Metal-interconnection-free integration of InGaN/GaN light emitting diodes with AlGaN/GaN high electron mobility transistors

    NASA Astrophysics Data System (ADS)

    Liu, Chao; Cai, Yuefei; Liu, Zhaojun; Ma, Jun; Lau, Kei May

    2015-05-01

    We report a metal-interconnection-free integration scheme for InGaN/GaN light emitting diodes (LEDs) and AlGaN/GaN high electron mobility transistors (HEMTs) by combining selective epi removal (SER) and selective epitaxial growth (SEG) techniques. SER of HEMT epi was carried out first to expose the bottom unintentionally doped GaN buffer and the sidewall GaN channel. A LED structure was regrown in the SER region with the bottom n-type GaN layer (n-electrode of the LED) connected to the HEMTs laterally, enabling monolithic integration of the HEMTs and LEDs (HEMT-LED) without metal-interconnection. In addition to saving substrate real estate, minimal interface resistance between the regrown n-type GaN and the HEMT channel is a significant improvement over metal-interconnection. Furthermore, excellent off-state leakage characteristics of the driving transistor can also be guaranteed in such an integration scheme.

  5. Improved interface quality and luminescence capability of InGaN/GaN quantum wells with Mg pretreatment

    NASA Astrophysics Data System (ADS)

    Wu, Zhengyuan; Shen, Xiyang; Xiong, Huan; Li, Qingfei; Kang, Junyong; Fang, Zhilai; Lin, Feng; Yang, Bilan; Lin, Shilin; Shen, Wenzhong; Zhang, Tong-Yi

    2016-02-01

    Interface modification of high indium content InGaN/GaN quantum wells was carried out by Mg pretreatment of the GaN barrier surface. The indium in the Mg-pretreated InGaN layer was homogeneously distributed, making the interfaces abrupt. The improved interface quality greatly enhanced light emission capacity. The cathodoluminescence intensity of the Mg-pretreated InGaN/GaN quantum wells was correspondingly much stronger than those of the InGaN/GaN quantum wells without Mg pretreatment.

  6. Panel discussion: Fumonisin Elimination. In: Proceedings of the Aflatoxin/Fumonisin Elimination and Fungal Genomics Workshops, October 22-24, 2007, Atlanta, Georgia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Summary of Presentations: The session was moderated by Scott Averhoff of the Texas Corn Producers Board. Ron Riley and Anthony Glenn from the USDA-ARS Toxicology & Mycotoxin Research Unit in Athens, GA presented a set of reports on the effects of fumonisin on corn seedling development and disease. F...

  7. Nanostructure and strain in InGaN/GaN superlattices grown in GaN nanowires.

    PubMed

    Kehagias, Th; Dimitrakopulos, G P; Becker, P; Kioseoglou, J; Furtmayr, F; Koukoula, T; Häusler, I; Chernikov, A; Chatterjee, S; Karakostas, Th; Solowan, H-M; Schwarz, U T; Eickhoff, M; Komninou, Ph

    2013-11-01

    The structural properties and the strain state of InGaN/GaN superlattices embedded in GaN nanowires were analyzed as a function of superlattice growth temperature, using complementary transmission electron microscopy techniques supplemented by optical analysis using photoluminescence and spatially resolved microphotoluminescence spectroscopy. A truncated pyramidal shape was observed for the 4 nm thick InGaN inclusions, where their (0001¯) central facet was delimited by six-fold {101¯l} facets towards the m-plane sidewalls of the nanowires. The defect content of the nanowires comprised multiple basal stacking faults localized at the GaN base/superlattice interface, causing the formation of zinc-blende cubic regions, and often single stacking faults at the GaN/InGaN bilayer interfaces. No misfit dislocations or cracks were detected in the heterostructure, implying a fully strained configuration. Geometrical phase analysis showed a rather uniform radial distribution of elastic strain in the (0001¯) facet of the InGaN inclusions. Depending on the superlattice growth temperature, the elastic strain energy is partitioned among the successive InGaN/GaN layers in the case of low-temperature growth, while at higher superlattice growth temperature the in-plane tensile misfit strain of the GaN barriers is accommodated through restrained diffusion of indium from the preceding InGaN layers. The corresponding In contents of the central facet were estimated at 0.42 and 0.25, respectively. However, in the latter case, successful reproduction of the experimental electron microscopy images by image simulations was only feasible, allowing for a much higher occupancy of indium adatoms at lattice sites of the semipolar facets, compared to the invariable 25% assigned to the polar facet. Thus, a high complexity in indium incorporation and strain allocation between the different crystallographic facets of the InGaN inclusions is anticipated and supported by the results of

  8. Inductively Coupled Plasma Etching of III-V Semiconductors in BCl(3)-Based Chemistries: Part 1: GaAs, GaN, GaP, GaSb and AlGaAs

    SciTech Connect

    Abernathy, C.R,; Han, J.; Hobson, W.S.; Hong, J.; Lambers, E.S.; Lee, J.W.; Maeda, T.; Pearton, S.J.; Shul, R.J.

    1998-12-04

    BC13, with addition of Nz, Ar or Hz, is found to provide smooth anisotropic pattern transfer in GaAs, GaN, GaP, GaSb and AIGriAs under Inductively Coupled Plasma conditions, Maxima in the etch rates for these materials are observed at 33% N2 or 87$'40 Hz (by flow) addition to BC13, whereas Ar addition does not show this behavior. Maximum etch rates are typically much higher for GaAs, Gap, GaSb and AIGaAs (-1,2 @rein) than for GaN (-0.3 ymu'min) due to the higher bond energies of the iatter. The rates decrease at higher pressure, saturate with source power (ion flux) and tend to show maxima with chuck power (ion energy). The etched surfaces remain stoichiometric over abroad range of plasma conditions.

  9. Transcript CONTU Meeting #10.

    ERIC Educational Resources Information Center

    National Commission on New Technological Uses of Copyrighted Works, Washington, DC.

    Testimony on the copyrightability of computer software was heard at the 10th Commission meeting held at the New York Public Library in November 1976. This transcript of the meeting also includes reports of the Commission subcommittees on photocopying, software, networks, and data bases. (Author/AP)

  10. Holding Effective Board Meetings.

    ERIC Educational Resources Information Center

    American Association of School Administrators, Arlington, VA.

    Advice and tested methods for management of meetings from superintendents and board members are combined in this reference book on conducting effective school board meetings. Intended for a wide readership, it contains three chapters and an exhibit section comprising over one-third of the document. Following a brief introduction, chapter 1,…

  11. RAS Ordinary Meetings

    NASA Astrophysics Data System (ADS)

    2014-02-01

    At the October 2013 meeting the President presented the Gold Medal to Prof. Chris Chapman, the Eddington Medal to Prof. James Binney, and Winton Capital Award to Dr Katherine Joy. Prof. Bob White gave the Harold Jeffreys Lecture on "Building the dynamic crust of Iceland by rifting and volcanism". At the November meeting, Prof. Eline Tolstoy gave the George Darwin Lecture on "Galactic palaeontology".

  12. 76 FR 54536 - Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-01

    ... From the Federal Register Online via the Government Publishing Office UNITED STATES INSTITUTE OF... provided in subsection 1706(h)(3) of the United States Institute of Peace Act, Public Law 98-525. Agenda: September 22, 2011 Board Meeting; Approval of Minutes of the One Hundred Fortieth Meeting (June 23-24,...

  13. 76 FR 37062 - Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-24

    ... Board (Access Board) plans to hold its regular committee and Board meetings in Washington, DC, Monday through Wednesday, July 11-13, 2011, at the times and location noted below. DATES: The schedule of events... Committee on Disability Research). 3-4p.m.--Ad Hoc Committee Meetings (Closed to Public). Wednesday, July...

  14. Trends in the prevalence of autism spectrum disorder, cerebral palsy, hearing loss, intellectual disability, and vision impairment, metropolitan atlanta, 1991-2010.

    PubMed

    Van Naarden Braun, Kim; Christensen, Deborah; Doernberg, Nancy; Schieve, Laura; Rice, Catherine; Wiggins, Lisa; Schendel, Diana; Yeargin-Allsopp, Marshalyn

    2015-01-01

    This study examined the prevalence and characteristics of autism spectrum disorder (ASD), cerebral palsy (CP), hearing loss (HL), intellectual disability (ID), and vision impairment (VI) over a 15-20 year time period, with specific focus on concurrent changes in ASD and ID prevalence. We used data from a population-based developmental disabilities surveillance program for 8-year-olds in metropolitan Atlanta. From 1991-2010, prevalence estimates of ID and HL were stable with slight increases in VI prevalence. CP prevalence was constant from 1993-2010. The average annual increase in ASD prevalence was 9.3% per year from 1996-2010, with a 269% increase from 4.2 per 1,000 in 1996 to 15.5 per 1,000 in 2010. From 2000-2010, the prevalence of ID without ASD was stable; during the same time, the prevalence of ASD with and without co-occurring ID increased by an average of 6.6% and 9.6% per year, respectively. ASD prevalence increases were found among both males and females, and among nearly all racial/ethnic subgroups and levels of intellectual ability. Average annual prevalence estimates from 1991-2010 underscore the significant community resources needed to provide early intervention and ongoing supports for children with ID (13.0 per 1,000), CP, (3.5 per 1,000), HL (1.4 per 1,000) and VI (1.3 in 1,000), with a growing urgency for children with ASD.

  15. Interaction between epidemiology and laboratory sciences in the study of birth defects: Design of birth defects risk factor surveillance in metropolitan Atlanta

    SciTech Connect

    Lynberg, M.C.; Khoury, M.J. )

    1993-01-01

    Despite years of research, the etiology of most birth defects remains largely unknown. Interview instruments have been the major tools in the search for environmental causes of birth defects. Because of respondents' problems with recognition and recall, interviews are limited in their capacity to measure certain exposures. Laboratory scientists can have a major impact on defining markers of environmental exposure and genetic susceptibility. The Centers for Disease Control is starting a case-control study of serious birth defects on the basis of a population-based surveillance system for birth defects diagnosed during the first year of life in metropolitan Atlanta, Each year, 300 infants with selected birth defects (case subjects) and 100 population-based control subjects (infants without birth defects) will be enrolled in an ongoing study that will supplement surveillance. In addition to conducting extensive maternal interviews, we will collect blood and urine specimens from case and control subjects and their mothers for laboratory testing. Eventually, some environmental sampling may be incorporated. Particular areas of emphasis are (1) nutritional factors, specifically measuring maternal folic acid levels and other micronutrients (e.g., zinc) to explore their role in the etiology of neural tube defects, (2) substance use, specifically measuring cocaine metabolites in the blood and urine to explore their role for specific vascular disruption defects, and (3) environmental factors such as pesticides and aflatoxins, to explore their potential relationships with specific defects. In addition, a DNA bank will be maintained to evaluate the role of specific candidate genes in the etiology of birth defects. The development and testing of these methods could be useful to assess the interaction between environmental exposures and genetic susceptibility in the etiology of birth defects. 15 refs., 1 fig., 1 tab.

  16. Fly-ash bases in the Atlanta District: Evaluation of surface treatment bond and year-two field performance evaluations. Research report, September 1996--1998

    SciTech Connect

    Estakhri, C.

    1998-12-01

    Hydrated fly ash is produced by allowing powder fly ash (Class C) from coal power plants to cure with moisture. The hydrated (cured) fly ash becomes a stiff material that can be crushed to form a synthetic aggregate. When properly processed and compacted to optimum moisture content, the hydrated fly ash continues to gain strength after placement as a base material. The Atlanta District has constructed six pavement sections since 1993 using hydrated fly ash as the flexible base material. This research project was initiated to evaluate and monitor performance and changes in material properties for these six pavements through the year 2001 and to evaluate a problem experienced during construction where the asphalt surface treatment did not bond well to the base. A laboratory study was performed to investigate the bond strength of different types of prime materials to the fly-ash base. Curing extent of the base was also a variable in the experiment. Results of the laboratory study revealed that the type of prime material used during construction did not contribute to the inadequate bond achieved. It is more likely attributable to the extent of base cure prior to application of an asphalt membrane. Construction recommendations are provided in this report aimed at achieving adequate bond of the surface treatment to the fly-ash base. Evaluation of pavement base performance was based on visual documentation, falling-weight deflectometer tests, ground penetrating radar, and compressive strengths of field cores. This report is an interim report documenting the performance evaluations conducted in the spring of 1998. This report covers the second annual evaluation in a series of five.

  17. Emission properties of heterostructures with a (GaAsSb-InGaAs)/GaAs bilayer quantum well

    SciTech Connect

    Zvonkov, B. N.; Nekorkin, S. M.; Vikhrova, O. V.; Dikareva, N. V.

    2013-09-15

    The specific features of the emission characteristics of GaAs-based heterostructures with a GaAs{sub 1-x}Sb{sub x}-In{sub y}Ga{sub 1-y}As bilayer quantum well are studied. The heterostructures are grown by metal-organic chemical vapor deposition (MOCVD). With an analysis of previously reported data on the MOCVD growth process taken into account, the temperature range (560-580 Degree-Sign C), the relation between the fluxes emitted by the sources of Group-V and -III elements ( Less-Than-Or-Equivalent-To 1), and the order of layer growth for the production of the active region of a GaAs/InGaP laser heterostructure are determined experimentally. The active region is a GaAs{sub 0.75}Sb{sub 0.25}-In{sub 0.2}Ga{sub 0.8}As bilayer quantum well. For the structure, a 1075-nm electroluminescence signal attributed to indirect transitions between the valence band of the GaAs{sub 0.75}Sb{sub 0.25} layer and the conduction band of the In{sub 0.2}Ga{sub 0.8}As layer is observed. An increase in the continuous-wave pump current yields a decrease in the 1075-nm emission intensity and initiates stable lasing at a wavelength of 1022 nm at a threshold current density of 1.4 kA cm{sup -2} at room temperature. Lasing occurs at transitions direct in coordinate space.

  18. Optical properties and defects in GaAsN and InGaAsN films and quantum well structures

    NASA Astrophysics Data System (ADS)

    Polyakov, A. Y.; Smirnov, N. B.; Govorkov, A. V.; Botchkarev, A. E.; Nelson, N. N.; Fahmi, M. M. E.; Griffin, J. A.; Khan, A.; Noor Mohammad, S.; Johnstone, D. K.; Bublik, V. T.; Chsherbatchev, K. D.; Voronova, M. I.; Kasatochkin, V. S.

    2002-12-01

    Photoluminescence and microcathodoluminescence spectra of thick-film GaAsN and InGaAsN structures and GaAs/InGaAsN, AlGaAs/InGaAsN quantum wells (QWs) were studied for InGaAsN layers with low nitrogen concentration of 0.35-0.5%. It is shown that in thick-film structures the bandedge luminescence intensity is strongly decreased in the row homoepitaxial GaAs, GaAsN on GaAs buffer, GaAsN, GaAs on GaAsN buffer, InGaAsN which correlates with the increasing concentration of electron traps with activation energy 0.53-0.55 eV. The type of defect bands in the thick-film structures was found to strongly depend on composition of the layers. For the GaAs/InGaAsN QW structures the intensity of luminescence was found to be more than an order of magnitude higher than in InGaAsN single films.

  19. Fabrication of vertical GaN/InGaN heterostructure nanowires using Ni-Au bi-metal catalysts.

    PubMed

    Ha, Ryong; Kim, Sung-Wook; Choi, Heon-Jin

    2013-06-26

    We have fabricated the vertically aligned coaxial or longitudinal heterostructure GaN/InGaN nanowires. The GaN nanowires are first vertically grown by vapor-liquid-solid mechanism using Au/Ni bi-metal catalysts. The GaN nanowires are single crystal grown in the [0001] direction, with a length and diameter of 1 to 10 μm and 100 nm, respectively. The vertical GaN/InGaN coaxial heterostructure nanowires (COHN) are then fabricated by the subsequent deposition of 2 nm of InxGa1-xN shell on the surface of GaN nanowires. The vertical GaN/InGaN longitudinal heterostructure nanowires (LOHN) are also fabricated by subsequent growth of an InGaN layer on the vertically aligned GaN nanowires using the catalyst. The photoluminescence from the COHN and LOHN indicates that the optical properties of GaN nanowires can be tuned by the formation of a coaxial or longitudinal InGaN layer. Our study demonstrates that the bi-metal catalysts are useful for growing vertical as well as heterostructure GaN nanowires. These vertically aligned GaN/InGaN heterostructure nanowires may be useful for the development of high-performance optoelectronic devices.

  20. Dilute GaAsN and GaInAsN grown by liquid phase epitaxy

    NASA Astrophysics Data System (ADS)

    Milanova, M.; Koleva, G.; Kakanakov, R.; Vitanov, P. K.; Alexieva, Z.; Goranova, E. A.; Arnaudov, B.; Evtimova, S.; Barthou, C.; Clerjaud, B.

    2010-04-01

    Dilute III-nitrides, such as GaAsN and GaInAsN, are of considerable current interest both from a fundamental point of view and for applications in solar cells, GaAs-based long-wavelength photodetectors and diode lasers. The addition of nitrogen leads to material properties that deviate strongly from those expected for conventional III-V solid solutions. The possibility was investigated to use liquid phase epitaxy to incorporate nitrogen in epitaxial GaAsN/GaAs and GaInAsN/GaAs heterostructures. The structures were grown from Ga- and Ga-In- melts containing powder GaN as a nitrogen source. The initial growth temperature was varied in the range 560°C - 660°C. The low temperature growth favors nitrogen incorporation in the epilayers. The optical transmission and photoluminescence spectra of a set of structures grown at different temperatures were studied showing ternary and quaternary dilute nitride solid solutions with nitrogen content about 0.2 at.%. The photoluminescence spectra show emission from localized nitrogen states as well.