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1

Fisica a escala de Planck usando o principio de incerteza generalizado: efeitos nas flutuações primordiais e buracos negros  

NASA Astrophysics Data System (ADS)

Em escalas proximas à escala de Planck todas as teorias perturbativas de cordas produzem essenciamente a mesma relação de conmutação entre as coordenadas e impulsos (a chamada "álgebra deformada"), permitindo assim estudar a física resultante independentemente dos detalhes da teoria de cordas que seja considerada correta. Este resultado completamente geral, que inclui as interações gravitacionais junto com o resto dos campos pode ser considerada uma versão generalizada (GUP) do Princípio de Incerteza de Heisenberg. Aplicamos neste trabalho essas relações de conmutação para dois sistemas físicos bem definidos: buracos negros de massas próximas à massa de Planck, e flutuações quânticas em pequenas escalas antes do universo sofrer inflação. Obtemos dois resultados concretos dos efeitos do GUP : o primeiro é que o GUP impede a evaporação completa de buracos negros microscópicos na extensão do formalismo semiclássico, deixando assim remanescentes de pequena massa que já foram postulados como candidatos a matéria escura. O segundo resultado é o 'smoothing' das flutuações primordiais em pequenas escalas que levariam à produção de buracos negros primordiais após a inflação, impedindo assim a produção abundante destes últimos e predizendo abundancias atuais bem menores do que os limites disponíveis. Concluimos que, analogamente a utilização do Princípio de Incerteza de Heisenberg para estudar e determinar propriedades fundamentais das interações sem gravitação, o GUP e uma ferramenta poderosa para estudar uma ampla variedade de sistemas trans-Planckianos e predizer seu comportamento dispensando cálculos mais detalhados proprios da teoria quântica da gravitação.

Horvath, J. E.; Custódio, P. S.

2003-08-01

2

As Atividades de Treinamento Em Sensoriamento Remoto No Instituto de Pesquisas Espaciais-Inpe/Brasil (Training Activities in Remote Sensing at the Instituto de Pesquisas Espaciais-Inpe/Brazil).  

National Technical Information Service (NTIS)

The Institute for Space Research (Instituto de Pesquisas Espaciais - INPE) began its research program in remote sensing in 1972, with the launching of the American LANDSAT satellites. Research was developed mainly in the field of natural resources, throug...

T. M. Sausen R. Pereiradacunha

1988-01-01

3

Computer B (NAS-NAS) Communications Support.  

National Technical Information Service (NTIS)

An analysis has been performed to determine the feasibility and desirability of incorporating into NADIN the message traffic currently serviced by the Computer B (NAS-NAS) Network. The use of NADIN to support NAS-NAS communications was found to be feasibl...

1981-01-01

4

NAS: The first year  

NASA Technical Reports Server (NTRS)

Discussed are the capabilities of NASA's Numerical Aerodynamic Simulation (NAS) Program and its application as an advanced supercomputing system for computational fluid dynamics (CFD) research. First, the paper describes the NAS computational system, called the NAS Processing System Network, and the advanced computational capabilities it offers as a consequence of carrying out the NAS pathfinder objective. Second, it presents examples of pioneering CFD research accomplished during NAS's first operational year. Examples are included which illustrate CFD applications for predicting fluid phenomena, complementing and supplementing experimentation, and aiding in design. Finally, pacing elements and future directions for CFD and NAS are discussed.

Bailey, F. R.; Kutler, Paul

1988-01-01

5

New NAS journal  

NASA Astrophysics Data System (ADS)

In April 1984 the National Academy of Sciences (NAS) will begin publishing a new quarterly focusing on science policy. Written primarily for legislators, diplomats, corporate managers, security analysts, and other public policy analysts, the new journal will deal with such diverse topics as arms control, economic competition, social change, and health care.Original articles are expected to create a 120-page periodical that will discuss policy issues on a sophisticated but nonspecialist level, in a manner similar to that which Foreign Affairs uses to discuss U.S. foreign policy topics, according to NAS.

6

NAS Parallel Benchmarks.  

National Technical Information Service (NTIS)

The NAS Parallel Benchmarks (NPB) are a suite of parallel computer performance benchmarks. They were originally developed at the NASA Ames Research Center in 1991 to assess high-end parallel supercomputers. Although they are no longer used as widely as th...

D. H. Bailey

2009-01-01

7

Observações simultâneas no óptico e infravermelho próximo dos BL Lacs PKS 2005-489 e PKS 2155-304 em diversas escalas de tempo  

NASA Astrophysics Data System (ADS)

A existência de variações rápidas de brilho em alguns blazares é um fenômeno bem comprovado, mas até agora não sabemos ao certo quais são os mecanismos físicos envolvidos. A maior dificuldade é a ausência de observações multibanda simultâneas que poderiam fornecer vínculos aos modelos. Buscando colaborar com a discussão estudamos o comportamento de dois BL Lacs, PKS 2005-489 e PKS 2155-304, em relação à variabilidade em diversas escalas de tempo, de poucos minutos até vários meses, com observações simultâneas em seis bandas espectrais (óptico e infravermelho próximo). Para tanto dois telescópios do LNA foram utilizados em conjunto nas campanhas observacionais realizadas em 2001 e 2002, cujos resultados são apresentados aqui. As duas fontes apresentaram características bastante diferentes, inclusive em relação à existência de variabilidade nos índices espectrais. Particularmente, registramos a primeira detecção de variações em escalas de tempo da ordem de poucos minutos em PKS 2005-489, com evidências da presença de um atraso entre as curvas de luz nas bandas V e R e a variação em R ocorrendo antes (o contrário do esperado no modelo de shock-in-jet). Em PKS 2155-304 detectamos pela primeira vez variabilidade em escalas de tempo de poucos minutos no infravermelho em um AGN. As observações indicam que as variações de brilho em blazares são o resultado da ação de mais de um fenômeno, especialmente em escalas de tempo muito curtas. Alguns cenários físicos são sugeridos para explicar os resultados observacionais.

Dominici, T. P.; Abraham, Z.; Galo, A. L.

2003-08-01

8

NASA's UAS NAS Access Project  

NASA Technical Reports Server (NTRS)

The vision of the Unmanned Aircraft System (UAS) Integration in the National Airspace System (NAS) Project is "A global transportation system which allows routine access for all classes of UAS." The goal of the UAS Integration in the NAS Project is to "contribute capabilities that reduce technical barriers related to the safety and operational challenges associated with enabling routine UAS access to the NAS." This goal will be accomplished through a two-phased approach based on development of system-level integration of key concepts, technologies and/or procedures, and demonstrations of integrated capabilities in an operationally relevant environment. Phase 1 will take place the first two years of the Project and Phase 2 will take place the following three years. The Phase 1 and 2 technical objectives are: Phase 1: Developing a gap analysis between current state of the art and the Next Generation Air Transportation System (NextGen) UAS Concept of Operations . Validating the key technical areas identified by this Project . Conducting initial modeling, simulation, and flight testing activities . Completing Sub-project Phase 1 deliverables (spectrum requirements, comparative analysis of certification methodologies, etc.) and continue Phase 2 preparation (infrastructure, tools, etc.) Phase 2: Providing regulators with a methodology for developing airworthiness requirements for UAS, and data to support development of certifications standards and regulatory guidance . Providing systems-level, integrated testing of concepts and/or capabilities that address barriers to routine access to the NAS. Through simulation and flight testing, address issues including separation assurance, communications requirements, and human systems integration in operationally relevant environments. The UAS in the NAS Project will demonstrate solutions in specific technology areas, which will address operational/safety issues related to UAS access to the NAS. Since the resource allocation for this Project is limited ($150M over the five years), the focus is on reducing the technical barriers where NASA has unique capabilities. As a result, technical areas, such as Sense and Avoid (SAA) and beyond line of sight command and control will not be addressed. While these are critical barriers to UAS access, currently, there is a great deal of global effort being exercised to address these challenge areas. Instead, specific technology development in areas where there is certainty that NASA can advance the research to high technology readiness levels will be the Project's focus. Specific sub-projects include Separation Assurance, Human Systems Integration, Communications, Certification, and Integrated Test and Evaluation. Each sub-project will transfer technologies to relevant key stakeholders and decision makers through research transition teams, technology forums, or through other analogous means.

Johnson, Charles W.

2011-01-01

9

NAS Panel faults export controls  

NASA Astrophysics Data System (ADS)

A study prepared by a top-level panel says that current export controls on militarily sensitive U.S. technology may be “overcorrecting” previous weaknesses in that system, resulting in “a complex and confusing control system” that makes it more difficult for U.S. businesses to compete in international markets. Moreover, this control system has “an increasingly corrosive effect” on U.S. relations with allies. The panel recommended that the United States concentrate more effort on bringing about uniformity in the export control policies of countries belonging to the Coordinating Committee on Multilateral Export Controls (CoCom), i.e., most of the member nations in NATO (the North Atlantic Treaty Organization) and Japan.The 21-member panel was appointed by the Committee on Science, Engineering, and Public Policy (COSEPUP), a joint unit of the National Academy of Sciences (NAS), the National Academy of Engineering (NAE), and the Institute of Medicine (IOM). The panel, composed of administrators, researchers, and former government officials, was chaired by AGU member Lew Allen, Jr., director of the Jet Propulsion Laboratory (Pasadena, Calif.) and former chief of staff of the U.S. Air Force. Their report was supported by NAS funds, by a number of private organizations (including AGU), by the U.S. Departments of Commerce, Defense, Energy, and State, by the National Science Foundation, and by the National Aeronautics and Space Administration.

Katzoff, Judith A.

10

Mapa Geologico de Venezuela a Escala 1:750,000  

USGS Publications Warehouse

Se presenta un mapa geologico digital de Venezuela sobre un fondo de relieve sombreado. Los datos geologicos e hidrologicos del norte del rio Orinoco proceden de la digitalizacion de mapas geologicos en papel a escala 1:500.000. Estos datos fueron integrados con el mapa geologico digital del Escudo de Guayana Venezolano, a su vez derivado de hojas en papel a escala 1:500.000. La informacion sobre los tipos de fallas mostrados en el mapa es igual que en las fuentes originales. Los poligonos geologicos fueron atribuidos por edad, litologia y nombre de la unidad siguiendo el Codigo geologico de Venezuela. Se incorporaron revisiones significativas de la geologia de la Cordillera de la Costa a partir de las nuevas hojas integradas a escala 1:25.000. Toda esta informacion geologico-estructural se sobrepuso a una imagen de relieve sombreado, producida por el procesamiento de los datos de radar interferometrico con 90 m (3 arcosegundos) de resolucion espacial obtenidos por la mision topografica de radar del transbordador espacial (SRTM). Las areas de la base de datos del SRTM carentes de informacion fueron llenadas por medio de la interpolacion de los datos de las celdas adyacentes. Para producir la imagen de relieve sombreado se uso una direccion de iluminacion de 315 deg con un angulo de 65 deg sobre el horizonte. La proyeccion usada en el mapa es conica equidistante, con latitudes de 4 y 9 deg norte como paralelos estandar y una longitud de 66 deg al oeste como meridiano central. Los datos en el mapa proceden primordialment de hojas a escala 1:500.000 y el producto esta preparado para una impresion optima en escala 1:750.000. Los usuarios pueden obtener ampliaciones mayores, sin embargo no se garantiza la precision del mapa a escalas mas detalladas. Especialmente en la region de Guayana, al sobreponer los mapas geologicos sobre la reciente imagen SRTM, se notan grandes discrepancias no sistematicas tanto en contactos como en fallas. Esto es debido a que los mapas geologicos de Guayana tienen como base topografica las imagenes de radar de vision lateral (SLAR), con muy control de campo de los a?os 1970's. La correccion de estos desfases esta planificada para el futuro.

Hackley, Paul C.; Urbani, Franco; Karlsen, Alex W.; Garrity, Christopher P.

2006-01-01

11

Validation of the Escala de Inteligencia Wechsler Para Adultos  

Microsoft Academic Search

This study examined the comparability between the Wechsler Adult Intelligence Scale-Revised (WAIS-R) and its Spanish-language adaptation the Escala De Inteligencia Para Adultos (EIWA). Fifty Puerto Rican, bilingual examinees who showed equal language proficiency in English and Spanish using the Bilingual Syntax Measure II (BSM-II) were administered both intelligence tests.^ Results of this study showed a mean difference between the EIWA

Carlos Y Maldonado

1995-01-01

12

GaInNAs laser gain  

SciTech Connect

The optical gain spectra for GaInNAs/GaAs quantum wells are computed using a microscopic laser theory. From these spectra, the peak gain and carrier radiative decay rate as functions of carrier density are determined. These dependences allow the study of the lasing threshold current density of GaInNAs/GaAs quantum well structures.

CHOW,WENG W.; JONES,ERIC D.; MODINE,NORMAND A.; KURTZ,STEVEN R.; ALLERMAN,ANDREW A.

2000-05-23

13

Handler Reflects on NAS, Science Issues  

ERIC Educational Resources Information Center

The current president of the National Academy of Science (NAS) is interviewed in this article. He discusses the reorganization of NAS and the National Research Council during his term of office. Concerns over environmental science, biochemistry research, and the decreasing role of science advisors to the Pentagon are presented. (MA)

Lepkowski, Wil

1978-01-01

14

NAS-current status and future plans  

NASA Technical Reports Server (NTRS)

The Numerical Aerodynamic Simulation (NAS) has met its first major milestone, the NAS Processing System Network (NPSN) Initial Operating Configuration (IOC). The program has met its goal of providing a national supercomputer facility capable of greatly enhancing the Nation's research and development efforts. Furthermore, the program is fulfilling its pathfinder role by defining and implementing a paradigm for supercomputing system environments. The IOC is only the begining and the NAS Program will aggressively continue to develop and implement emerging supercomputer, communications, storage, and software technologies to strengthen computations as a critical element in supporting the Nation's leadership role in aeronautics.

Bailey, F. R.

1987-01-01

15

NASA Advanced Supercomputing (NAS) User Services Group  

NASA Technical Reports Server (NTRS)

This viewgraph presentation provides an overview of NAS (NASA Advanced Supercomputing), its goals, and its mainframe computer assets. Also covered are its functions, including systems monitoring and technical support.

Pandori, John; Hamilton, Chris; Niggley, C. E.; Parks, John W. (Technical Monitor)

2002-01-01

16

The NAS Parallel Benchmarks 2.0  

Microsoft Academic Search

We describe a set of implementations of the NAS Parallel Benchmarks based on Fortran 77 and the MPI message passing standard. These implementations,which are intended to be run with little or no tuning, approximate the performance a typical user can expect for a portable parallel program on a distributed memory computer. They complement rather than replace the originalNAS Parallel Benchmarks.We

David Bailey; Tim Harris; William Saphir; Rob Van Der Wijngaart; Alex Woo; Maurice Yarrow

1995-01-01

17

GaInNAs Laser Gain.  

National Technical Information Service (NTIS)

The optical gain spectra for GaInNAs/GaAs quantum wells are computed using a microscopic laser theory. From these spectra, the peak gain and carrier radiative decay rate as functions of carrier density are determined. These dependences allow the study of ...

W. E. Chow E. D. Jones N. A. Modine S. R. Kurtz A. A. Allerman

2000-01-01

18

Security Controls Hurt Research, NAS Warns.  

ERIC Educational Resources Information Center

A National Academy of Sciences (NAS) report found no evidence that leaks of technical information from universities or other research centers have damaged national security. However, in areas where control is warranted, decisions should be based on criteria. These criteria and issues related to security control and technological transfer are…

Kolata, Gina

1982-01-01

19

Nas Parallel Benchmark Results 3-94  

Microsoft Academic Search

The NAS Parallel Benchmarks have been developed at NASA Ames Research Center to study theperformance of parallel supercomputers. The eight benchmark problems are specified in a "pencil andpaper" fashion. In other words, the complete details of the problem to be solved are given in a technicaldocument, and except for a few restrictions, benchmarkers are mostly free to select the language

David H. Bailey; Eric Barszcz; Leonardo Dagum; Horst D. Simon

1994-01-01

20

Development update of the NAS battery  

Microsoft Academic Search

With the commercialization of the sodium-sulfur (NAS) battery in Japan by the Tokyo Electric Power Company (TEPCO) and NGK Insulators, Ltd. (NGK), and demonstration projects underway and under development in the US by the American Electric Power Company (AEP) and others, standard designs for high value target applications have been advancing. In particular, a reference peak shaving-based design has evolved

M. Kamibayashi; D. K. Nichols; T. Oshima

2002-01-01

21

NAS Technical Summaries, March 1993 - February 1994  

NASA Technical Reports Server (NTRS)

NASA created the Numerical Aerodynamic Simulation (NAS) Program in 1987 to focus resources on solving critical problems in aeroscience and related disciplines by utilizing the power of the most advanced supercomputers available. The NAS Program provides scientists with the necessary computing power to solve today's most demanding computational fluid dynamics problems and serves as a pathfinder in integrating leading-edge supercomputing technologies, thus benefitting other supercomputer centers in government and industry. The 1993-94 operational year concluded with 448 high-speed processor projects and 95 parallel projects representing NASA, the Department of Defense, other government agencies, private industry, and universities. This document provides a glimpse at some of the significant scientific results for the year.

1995-01-01

22

NAS Grid Benchmarks. 1.0  

NASA Technical Reports Server (NTRS)

We provide a paper-and-pencil specification of a benchmark suite for computational grids. It is based on the NAS (NASA Advanced Supercomputing) Parallel Benchmarks (NPB) and is called the NAS Grid Benchmarks (NGB). NGB problems are presented as data flow graphs encapsulating an instance of a slightly modified NPB task in each graph node, which communicates with other nodes by sending/receiving initialization data. Like NPB, NGB specifies several different classes (problem sizes). In this report we describe classes S, W, and A, and provide verification values for each. The implementor has the freedom to choose any language, grid environment, security model, fault tolerance/error correction mechanism, etc., as long as the resulting implementation passes the verification test and reports the turnaround time of the benchmark.

VanderWijngaart, Rob; Frumkin, Michael; Biegel, Bryan A. (Technical Monitor)

2002-01-01

23

The NAS battery: a multifunction energy storage system  

Microsoft Academic Search

This paper presents an overview of the first U.S. demonstration of stationary sodium sulfur (NAS) battery energy storage technology hosted by the American electric power (AEP). The NAS batteries are supplied by NGK insulators, Ltd. in Japan. ABB, Inc. of New Berlin, Wisconsin supplied the power conversion system that integrates direct current (DC) from the NAS battery with the alternating

B. Tamyurek; D. K. Nichols; O. Demirci

2003-01-01

24

NAS Parallel Benchmarks. 2.4  

NASA Technical Reports Server (NTRS)

We describe a new problem size, called Class D, for the NAS Parallel Benchmarks (NPB), whose MPI source code implementation is being released as NPB 2.4. A brief rationale is given for how the new class is derived. We also describe the modifications made to the MPI (Message Passing Interface) implementation to allow the new class to be run on systems with 32-bit integers, and with moderate amounts of memory. Finally, we give the verification values for the new problem size.

VanderWijngaart, Rob; Biegel, Bryan A. (Technical Monitor)

2002-01-01

25

Dynamics of time-resolved photoluminescence in GaInNAs and GaNAsSb solar cells  

PubMed Central

We report a time-resolved photoluminescence study for GaInNAs and GaNAsSb p-i-n bulk solar cells grown on GaAs(100). In particular, we studied the extent to which the carrier lifetime decreases with the increase of N content. Rapid thermal annealing proved to significantly increase the decay times by a factor of 10 to 12 times, for both GaInNAs and GaNAsSb heterostructures, while for the 1-eV bandgap GaNAsSb structure, grown at the same growth conditions as the GaInNAs, the photoluminescence decay time remained slightly below 100 ps after annealing; the approximately 1.15-eV GaInNAs p-i-n solar cell exhibited a lifetime as long as 900 ps. PACS 78.47.D; 78.55.Cr; 88.40.hj

2014-01-01

26

NAS Parallel Benchmarks, Multi-Zone Versions  

NASA Technical Reports Server (NTRS)

We describe an extension of the NAS Parallel Benchmarks (NPB) suite that involves solving the application benchmarks LU, BT and SP on collections of loosely coupled discretization meshes. The solutions on the meshes are updated independently, but after each time step they exchange boundary value information. This strategy, which is common among structured-mesh production flow solver codes in use at NASA Ames and elsewhere, provides relatively easily exploitable coarse-grain parallelism between meshes. Since the individual application benchmarks also allow fine-grain parallelism themselves, this NPB extension, named NPB Multi-Zone (NPB-MZ), is a good candidate for testing hybrid and multi-level parallelization tools and strategies.

vanderWijngaart, Rob F.; Haopiang, Jin

2003-01-01

27

Factor Structure of the Escala de Autoeficacia para la Depresión en Adolescentes (EADA)  

Microsoft Academic Search

The current concept and measures of self-efficacy for depression in adolescents do not consider developmental and cultural aspects essential to understand and assess this construct in Latino youth. We examined the factor structure of the Escala de Autoeficacia para la Depresión en Adolescentes (EADA), a Spanish instrument designed to assess this construct as experienced by this population. Participants were 116

Mirella Díaz-Santos; Eduardo Cumba-Avilés; Guillermo Bernal; Carmen Rivera-Medina

2011-01-01

28

The Need for Vendor Source Code at NAS. Revised  

NASA Technical Reports Server (NTRS)

The Numerical Aerodynamic Simulation (NAS) Facility has a long standing practice of maintaining buildable source code for installed hardware. There are two reasons for this: NAS's designated pathfinding role, and the need to maintain a smoothly running operational capacity given the widely diversified nature of the vendor installations. NAS has a need to maintain support capabilities when vendors are not able; diagnose and remedy hardware or software problems where applicable; and to support ongoing system software development activities whether or not the relevant vendors feel support is justified. This note provides an informal history of these activities at NAS, and brings together the general principles that drive the requirement that systems integrated into the NAS environment run binaries built from source code, onsite.

Carter, Russell; Acheson, Steve; Blaylock, Bruce; Brock, David; Cardo, Nick; Ciotti, Bob; Poston, Alan; Wong, Parkson; Chancellor, Marisa K. (Technical Monitor)

1997-01-01

29

NO3-/NO2- assimilation in halophilic archaea: physiological analysis, nasA and nasD expressions.  

PubMed

The haloarchaeon Haloferax mediterranei is able to assimilate nitrate or nitrite using the assimilatory nitrate pathway. An assimilatory nitrate reductase (Nas) and an assimilatory nitrite reductase (NiR) catalyze the first and second reactions, respectively. The genes involved in this process are transcribed as two messengers, one polycistronic (nasABC; nasA encodes Nas) and one monocistronic (nasD; codes for NiR). Here we report the Hfx mediterranei growth as well as the Nas and NiR activities in presence of high nitrate, nitrite and salt concentrations, using different approaches such as physiological experiments and enzymatic activities assays. The nasA and nasD expression profiles are also analysed by real-time quantitative PCR. The results presented reveal that the assimilatory nitrate/nitrite pathway in Hfx mediterranei takes place even if the salt concentration is higher than those usually present in the environments where this microorganism inhabits. This haloarchaeon grows in presence of 2 M nitrate or 50 mM nitrite, which are the highest nitrate and nitrite concentrations described from a prokaryotic microorganism. Therefore, it could be attractive for bioremediation applications in sewage plants where high salt, nitrate and nitrite concentrations are detected in wastewaters and brines. PMID:19593595

Martínez-Espinosa, Rosa María; Lledó, Belén; Marhuenda-Egea, Frutos C; Díaz, Susana; Bonete, María José

2009-09-01

30

Estudo de não gaussianidade nas anisotropias da RCF medidas Wmap  

NASA Astrophysics Data System (ADS)

A investigação do campo de flutuações da Radiação Cósmica de Fundo (RCF) pode oferecer um importante teste para os modelos cosmológicos que descrevem a origem e a evolução das flutuações primordiais. De um lado, apresenta-se o modelo inflacionário que prevê um espectro de flutuações adiabáticas distribuídas segundo uma gaussiana e, de outro, os modelos de defeitos topológicos (dentre outros) que descrevem um mecanismo para a geração de flutuações de isocurvatura que obedecem a uma distribuição não gaussiana. Este trabalho tem como objetivo caracterizar traços do modelo não gaussiano de campo misto (entre flutuações adiabáticas e de isocurvatura) nos mapas do Wilkinson Microwave Anisotropy Probe (WMAP). Simulações das anisotropias da RCF no contexto de mistura indicam traços marcantes na distribuição das flutuações de temperatura, mesmo quando consideradas pequenas contribuições do campo de isocurvatura (da ordem de 0.001). O efeito da mistura entre os campos resulta na transferência de potência de flutuações em escalas angulares intermediárias para flutuações em pequenas escalas angulares. Este efeito pode ser caracterizado pela relação entre as amplitudes dos primeiros picos acústicos no espectro de potência da RCF. Neste trabalho, investigamos a contribuição do campo de isocurvatura, no contexto de mistura, sobre as observações recentes da RCF realizadas pelo WMAP. As previsões do modelo de campo misto, uma vez confrontadas com as observações em pequenas escalas angulares, podem ajudar a revelar a natureza das flutuações primordiais.

Andrade, A. P. A.; Wuensche, C. A.; Ribeiro, A. L. B.

2003-08-01

31

NAS Systems Division at NASA Ames Research Center  

NSDL National Science Digital Library

The NASA Advanced Supercomputing (NAS) division is part of the Ames Research Center Information Sciences and Technology Directorate. The NAS home page describes "leading-edge high performance computing and its role in many of NASA's critical missions for the 21st century." The site provides news and feature stories of NAS projects, but most of the site's information is in the Research & Technology section. There, you will find descriptions of many research areas and their corresponding papers and reports. Several software packages are available for download; however, some are restricted. Sample datasets of research simulation results are also offered for scientific use.

2002-01-01

32

Desarrollo y Propiedades Psicométricas de la Escala de Autoeficacia para la Depresión en Adolescentes (EADA)  

Microsoft Academic Search

Self-efficacy questionnaires used with adolescents are mostly youth-adapted adult measures or scales developed to assess general perceived self-efficacy. The purpose of this study was to develop and assess the psychometric properties of the Escala de Autoeficacia para la Depresión en Adolescentes (EADA). Additionally, the Emotional Self-efficacy subscale from the Self-Efficacy Questionnaire for Children and the Children's Depression Inventory-Short Version were

MIRELLA DÍAZ-SANTOS; EDUARDO CUMBA-AVILÉS; GUILLERMO BERNAL; CARMEN RIVERA-MEDINA

2008-01-01

33

Annealing effects on the nanoscale indium and nitrogen distribution in Ga(NAs) and (GaIn)(NAs) quantum wells  

NASA Astrophysics Data System (ADS)

III/V semiconductors containing dilute amounts of nitrogen are metastable and need to be thermally treated after growth to optimize optoelectronic properties. The influence of thermal annealing on the nitrogen depth profile in metal organic vapor phase epitaxygrown Ga(NAs)/GaAs as well as (GaIn)(NAs)/GaAs heterostructures is examined on a nanometer scale by combining several high resolution transmission electron microscopy techniques, also with Rutherford backscattering spectrometry. Annealing conditions, which are optimized for quaternary alloys with respect to photoluminescence intensity, do not result in element redistribution for the In containing material. Contrary to the quaternary material, the result of annealing the ternary Ga(NAs) is a pronounced pileup of the nitrogen profile without any out diffusion of nitrogen. These findings have important influence on device structures, which often contain Ga(NAs) barriers for strain-compensation purposes together with (GaIn)(NAs) active regions. In the light of metastability considerations for the ternary and quaternary alloy, one can conclude that the In contained in the quaternary material stabilizes the material and suppresses phase separation. Consequently (GaIn)(NAs) is more stable than its ternary counterpart Ga(NAs).

Volz, K.; Torunski, T.; Rubel, O.; Stolz, W.; Kruse, P.; Gerthsen, D.; Schowalter, M.; Rosenauer, A.

2007-10-01

34

Performance and Scalability of the NAS Parallel Benchmarks in Java.  

National Technical Information Service (NTIS)

Several features make Java an attractive choice for scientific applications. In order to gauge the applicability of Java to Computational Fluid Dynamics (CFD), we have implemented the NAS (NASA Advanced Supercomputing) Parallel Benchmarks in Java. The per...

M. A. Frumkin M. Schultz H. Jin J. Yan

2002-01-01

35

A Review of the NAS Manpower Studies. Volume II.  

National Technical Information Service (NTIS)

Volume II provides assessments of the four NAS Manpower Studies by independent, external consultants with the purpose of assisting the Department of Medicine and Surgery in the decision-making process necessary in dealing with the recommendations of the N...

1977-01-01

36

Policy Recommendations to VA Leave NAS at Odds with Congress  

ERIC Educational Resources Information Center

Describes adverse congressional reaction to a recent National Academy of Sciences (NAS) recommendation that the Veteran's Administration's (VA) health care system be phased into a general health care system. (SL)

Walsh, John

1978-01-01

37

Implementation of the NAS Parallel Benchmarks in Java.  

National Technical Information Service (NTIS)

Several features make Java an attractive choice for High Performance Computing (HPC). In order to gauge the applicability of Java to Computational Fluid Dynamics (CFD), we have implemented the NAS (NASA Advanced Supercomputing) Parallel Benchmarks in Java...

M. A. Frumkin M. Schultz H. Jin J. Yan

2002-01-01

38

The NAS Parallel Benchmarks 2.1 Results  

NASA Technical Reports Server (NTRS)

We present performance results for version 2.1 of the NAS Parallel Benchmarks (NPB) on the following architectures: IBM SP2/66 MHz; SGI Power Challenge Array/90 MHz; Cray Research T3D; and Intel Paragon. The NAS Parallel Benchmarks are a widely-recognized suite of benchmarks originally designed to compare the performance of highly parallel computers with that of traditional supercomputers.

Saphir, William; Woo, Alex; Yarrow, Maurice

1996-01-01

39

Natural attenuation software (NAS): Assessing remedial strategies and estimating timeframes  

USGS Publications Warehouse

Natural Attenuation Software (NAS) is a screening tool to estimate remediation timeframes for monitored natural attenuation (MNA) and to assist in decision-making on the level of source zone treatment in conjunction with MNA using site-specific remediation objectives. Natural attenuation processes that NAS models include are advection, dispersion, sorption, non-aqueous phase liquid (NAPL) dissolution, and biodegradation of either petroleum hydrocarbons or chlorinated ethylenes. Newly-implemented enhancements to NAS designed to maximize the utility of NAS for site managers were observed. NAS has expanded source contaminant specification options to include chlorinated ethanes and chlorinated methanes, and to allow for the analysis of any other user-defined contaminants that may be subject to microbially-mediated transformations (heavy metals, radioisotopes, etc.). Included is the capability to model co-mingled plumes, with constituents from multiple contaminant categories. To enable comparison of remediation timeframe estimates between MNA and specific engineered remedial actions , NAS was modified to incorporate an estimation technique for timeframes associated with pump-and-treat remediation technology for comparison to MNA. This is an abstract of a paper presented at the 8th International In Situ and On-Site Bioremediation Symposium (Baltimore, MD 6/6-9/2005).

Mendez, E.; Widdowson, M.; Chapelle, F.; Casey, C.

2005-01-01

40

Photoreflectance spectroscopy of step-like GaInNAs/GaInNAs/GaAs quantum wells  

NASA Astrophysics Data System (ADS)

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.

Kudrawiec, R.; Andrzejewski, J.; Misiewicz, J.; Gollub, D.; Forchel, A.

2005-05-01

41

Upgrades to the Probabilistic NAS Platform Air Traffic Simulation Software  

NASA Technical Reports Server (NTRS)

This document is the final report for the project entitled "Upgrades to the Probabilistic NAS Platform Air Traffic Simulation Software." This report consists of 17 sections which document the results of the several subtasks of this effort. The Probabilistic NAS Platform (PNP) is an air operations simulation platform developed and maintained by the Saab Sensis Corporation. The improvements made to the PNP simulation include the following: an airborne distributed separation assurance capability, a required time of arrival assignment and conformance capability, and a tactical and strategic weather avoidance capability.

Hunter, George; Boisvert, Benjamin

2013-01-01

42

PM MEASURES AND HUMAN EXPOSURE (NAS 1 & 2)  

EPA Science Inventory

Under NAS research topics 1 & 2, EPA will study the mechanisms that influence the entry of fine particles into the indoor environment and to determine the emission characteristics of PM from priority indoor sources including vacuuming and combustion. Laboratory and test house st...

43

Unstructured Adaptive (UA) NAS Parallel Benchmark. Version 1.0  

NASA Technical Reports Server (NTRS)

We present a complete specification of a new benchmark for measuring the performance of modern computer systems when solving scientific problems featuring irregular, dynamic memory accesses. It complements the existing NAS Parallel Benchmark suite. The benchmark involves the solution of a stylized heat transfer problem in a cubic domain, discretized on an adaptively refined, unstructured mesh.

Feng, Huiyu; VanderWijngaart, Rob; Biswas, Rupak; Mavriplis, Catherine

2004-01-01

44

The nasB operon and nasA gene are required for nitrate/nitrite assimilation in Bacillus subtilis.  

PubMed Central

Bacillus subtilis can use either nitrate or nitrite as a sole source of nitrogen. The isolation of the nasABCDEF genes of B. subtilis, which are required for nitrate/nitrite assimilation, is reported. The probable gene products include subunits of nitrate/nitrite reductases and an enzyme involved in the synthesis of siroheme, a cofactor for nitrite reductase.

Ogawa, K; Akagawa, E; Yamane, K; Sun, Z W; LaCelle, M; Zuber, P; Nakano, M M

1995-01-01

45

Applications Performance on NAS Intel Paragon XP/S - 15#  

NASA Technical Reports Server (NTRS)

The Numerical Aerodynamic Simulation (NAS) Systems Division received an Intel Touchstone Sigma prototype model Paragon XP/S- 15 in February, 1993. The i860 XP microprocessor with an integrated floating point unit and operating in dual -instruction mode gives peak performance of 75 million floating point operations (NIFLOPS) per second for 64 bit floating point arithmetic. It is used in the Paragon XP/S-15 which has been installed at NAS, NASA Ames Research Center. The NAS Paragon has 208 nodes and its peak performance is 15.6 GFLOPS. Here, we will report on early experience using the Paragon XP/S- 15. We have tested its performance using both kernels and applications of interest to NAS. We have measured the performance of BLAS 1, 2 and 3 both assembly-coded and Fortran coded on NAS Paragon XP/S- 15. Furthermore, we have investigated the performance of a single node one-dimensional FFT, a distributed two-dimensional FFT and a distributed three-dimensional FFT Finally, we measured the performance of NAS Parallel Benchmarks (NPB) on the Paragon and compare it with the performance obtained on other highly parallel machines, such as CM-5, CRAY T3D, IBM SP I, etc. In particular, we investigated the following issues, which can strongly affect the performance of the Paragon: a. Impact of the operating system: Intel currently uses as a default an operating system OSF/1 AD from the Open Software Foundation. The paging of Open Software Foundation (OSF) server at 22 MB to make more memory available for the application degrades the performance. We found that when the limit of 26 NIB per node out of 32 MB available is reached, the application is paged out of main memory using virtual memory. When the application starts paging, the performance is considerably reduced. We found that dynamic memory allocation can help applications performance under certain circumstances. b. Impact of data cache on the i860/XP: We measured the performance of the BLAS both assembly coded and Fortran coded. We found that the measured performance of assembly-coded BLAS is much less than what memory bandwidth limitation would predict. The influence of data cache on different sizes of vectors is also investigated using one-dimensional FFTs. c. Impact of processor layout: There are several different ways processors can be laid out within the two-dimensional grid of processors on the Paragon. We have used the FFT example to investigate performance differences based on processors layout.

Saini, Subhash; Simon, Horst D.; Copper, D. M. (Technical Monitor)

1994-01-01

46

Characterizations of GaInNAs/GaAs quantum wells  

NASA Astrophysics Data System (ADS)

Heterostructures of GaInNAs/GaAs multiple quantum wells were characterized by high resolution x-ray diffraction. Complexity and stress compensating effect of such quaternary alloys cause many characterization problems. One of the most important issue is determination of composition of the material, which cannot be performed utilizing only one characterization method. That is why structural analysis had to be related with optical measurements which give different information correlated with composition. A comparison of theoretical calculations of energy band gap with energy of transitions in GaInNAs QWs from photoluminescence or contactless electro-reflectance measurements supplement the results of HRXRD and gives complete information about the structure required as a feedback to develop technology of heterostructures epitaxial growth.

Bielak, Katarzyna; Pucicki, Damian; ?ciana, Beata; Radziewicz, Damian; Dawidowski, Wojciech; Badura, Mikolaj; Kudrawiec, Robert; Serafi?czuk, Jaros?aw; T?acza?a, Marek

2013-07-01

47

NAS Grid Benchmarks: A Tool for Grid Space Exploration  

NASA Technical Reports Server (NTRS)

We present an approach for benchmarking services provided by computational Grids. It is based on the NAS Parallel Benchmarks (NPB) and is called NAS Grid Benchmark (NGB) in this paper. We present NGB as a data flow graph encapsulating an instance of an NPB code in each graph node, which communicates with other nodes by sending/receiving initialization data. These nodes may be mapped to the same or different Grid machines. Like NPB, NGB will specify several different classes (problem sizes). NGB also specifies the generic Grid services sufficient for running the bench-mark. The implementor has the freedom to choose any specific Grid environment. However, we describe a reference implementation in Java, and present some scenarios for using NGB.

Frumkin, Michael; VanderWijngaart, Rob F.; Biegel, Bryan (Technical Monitor)

2001-01-01

48

Hybrid Network Architectures for the Next Generation NAS  

NASA Technical Reports Server (NTRS)

To meet the needs of the 21st Century NAS, an integrated, network-centric infrastructure is essential that is characterized by secure, high bandwidth, digital communication systems that support precision navigation capable of reducing position errors for all aircraft to within a few meters. This system will also require precision surveillance systems capable of accurately locating all aircraft, and automatically detecting any deviations from an approved path within seconds and be able to deliver high resolution weather forecasts - critical to create 4- dimensional (space and time) profiles for up to 6 hours for all atmospheric conditions affecting aviation, including wake vortices. The 21st Century NAS will be characterized by highly accurate digital data bases depicting terrain, obstacle, and airport information no matter what visibility conditions exist. This research task will be to perform a high-level requirements analysis of the applications, information and services required by the next generation National Airspace System. The investigation and analysis is expected to lead to the development and design of several national network-centric communications architectures that would be capable of supporting the Next Generation NAS.

Madubata, Christian

2003-01-01

49

Comparison of GaNAsSb and GaNAs as quantum-well barriers for GaInNAsSb optoelectronic devices operating at 1.3-1.55 {mu}m  

SciTech Connect

GaNAsSb/GaAs quantum wells were grown by solid-source molecular-beam epitaxy utilizing a radio-frequency nitrogen plasma source. The GaNAsSb layers, originally the quantum well barrier materials for GaInNAs(Sb) devices, were studied for their general growth characteristics as well as their structural and optical properties, which give an indication of its quality as a quantum well barrier material. Reflection high-energy electron diffraction, high-resolution x-ray diffraction, secondary-ion mass spectroscopy, and photoluminescence (PL) measurements were used to study those properties. The growth parameters including arsenic overpressure and substrate temperature were changed systematically to determine the properties during deposition and to optimize these conditions. It was found that the addition of antimony to GaNAs did not improve the material as it did for GaInNAs. PL measurements indicated a decreasing optical quality with an increasing substrate temperature and no change with the arsenic overpressure. In addition, the addition of antimony had eliminated the lattice-strain compensation provided by the GaNAs barriers. Using GaNAs rather than GaNAsSb barriers in the GaInNAs(Sb) devices was found to be advantageous and has dramatically improved the performance of long-wavelength GaAs-based lasers.

Yuen, Homan B.; Bank, Seth R.; Wistey, Mark A.; Harris, James S. Jr.; Moto, Akihiro [Department of Electrical Engineering, Solid State and Photonics Laboratory, CIS-X 126X, Via Ortega, Stanford University, Stanford, California 94305-4075 (United States); Innovation Core Sumimoto Electric Industries, Ltd., Santa Clara, California 95051 (United States)

2004-12-01

50

Nitrogen regulation of nasA and the nasB operon, which encode genes required for nitrate assimilation in Bacillus subtilis.  

PubMed Central

The divergently transcribed nasA gene and nasB operon are required for nitrate and nitrite assimilation in Bacillus subtilis. The beta-galactosidase activity of transcriptional lacZ fusions from the nasA and nasB promoters was high when cells were grown in minimal glucose medium containing poor nitrogen sources such as nitrate, proline, or glutamate. The expression was very low when ammonium or glutamine was used as the sole nitrogen source. The repression of the genes during growth on good sources of nitrogen required wild-type glutamine synthetase (GlnA), but not GlnR, the repressor of the glnRA operon. Primer extension analysis showed that the -10 region of each promoter resembles those of sigma A-recognized promoters. Between the divergently oriented nasA and nasB promoters is a region of dyad symmetry. Mutational analysis led to the conclusion that this sequence is required in cis for the activation of both nasA and nasB. The derepression of these genes in a glnA mutant also required this sequence. These results suggest that an unidentified transcriptional activator and glutamine synthetase function in the regulation of nasA and the nasB operon.

Nakano, M M; Yang, F; Hardin, P; Zuber, P

1995-01-01

51

National Airspace System: System Effectiveness Operational Concept NAS-SR-138.  

National Technical Information Service (NTIS)

A requirement for the National Airspace System (NAS) is to provide for system effectiveness as identified in the NAS System Requirements Specification (NASSRS). This operational concept is one of many high level documents that will, in total, describe the...

H. Nelson, T. Pckerell, W. Trent

1992-01-01

52

48 CFR 852.236-82 - Payments under fixed-price construction contracts (without NAS).  

Code of Federal Regulations, 2010 CFR

...fixed-price construction contracts (without NAS). 852.236-82 Section 852.236-82...fixed-price construction contracts (without NAS). As prescribed in 832.111, insert...section entitled âNetwork Analysis System (NAS).â Payments Under Fixed-Price...

2009-10-01

53

48 CFR 852.236-82 - Payments under fixed-price construction contracts (without NAS).  

Code of Federal Regulations, 2010 CFR

...fixed-price construction contracts (without NAS). 852.236-82 Section 852.236-82...fixed-price construction contracts (without NAS). As prescribed in 832.111, insert...section entitled âNetwork Analysis System (NAS).â Payments Under Fixed-Price...

2010-10-01

54

76 FR 1511 - Amendment of Class D Airspace; Fort Worth NAS JRB (Carswell Field), TX  

Federal Register 2010, 2011, 2012, 2013

...Amendment of Class D Airspace; Fort Worth NAS JRB (Carswell Field), TX AGENCY: Federal...within the Fort Worth Naval Air Station (NAS) JRB (Carswell Field), TX, area and...geographic coordinates of the Fort Worth NAS JRB (Carswell Field) Class D...

2011-01-11

55

NAS Requirements Checklist for Job Queuing/Scheduling Software  

NASA Technical Reports Server (NTRS)

The increasing reliability of parallel systems and clusters of computers has resulted in these systems becoming more attractive for true production workloads. Today, the primary obstacle to production use of clusters of computers is the lack of a functional and robust Job Management System for parallel applications. This document provides a checklist of NAS requirements for job queuing and scheduling in order to make most efficient use of parallel systems and clusters for parallel applications. Future requirements are also identified to assist software vendors with design planning.

Jones, James Patton

1996-01-01

56

Navigation in Grid Space with the NAS Grid Benchmarks  

NASA Technical Reports Server (NTRS)

We present a navigational tool for computational grids. The navigational process is based on measuring the grid characteristics with the NAS Grid Benchmarks (NGB) and using the measurements to assign tasks of a grid application to the grid machines. The tool allows the user to explore the grid space and to navigate the execution at a grid application to minimize its turnaround time. We introduce the notion of gridscape as a user view of the grid and show how it can be me assured by NGB, Then we demonstrate how the gridscape can be used with two different schedulers to navigate a grid application through a rudimentary grid.

Frumkin, Michael; Hood, Robert; Biegel, Bryan A. (Technical Monitor)

2002-01-01

57

Parallelization of NAS Benchmarks for Shared Memory Multiprocessors  

NASA Technical Reports Server (NTRS)

This paper presents our experiences of parallelizing the sequential implementation of NAS benchmarks using compiler directives on SGI Origin2000 distributed shared memory (DSM) system. Porting existing applications to new high performance parallel and distributed computing platforms is a challenging task. Ideally, a user develops a sequential version of the application, leaving the task of porting to new generations of high performance computing systems to parallelization tools and compilers. Due to the simplicity of programming shared-memory multiprocessors, compiler developers have provided various facilities to allow the users to exploit parallelism. Native compilers on SGI Origin2000 support multiprocessing directives to allow users to exploit loop-level parallelism in their programs. Additionally, supporting tools can accomplish this process automatically and present the results of parallelization to the users. We experimented with these compiler directives and supporting tools by parallelizing sequential implementation of NAS benchmarks. Results reported in this paper indicate that with minimal effort, the performance gain is comparable with the hand-parallelized, carefully optimized, message-passing implementations of the same benchmarks.

Waheed, Abdul; Yan, Jerry C.; Saini, Subhash (Technical Monitor)

1998-01-01

58

Una aplicación de la escala de fobia a los alimentos nuevos. El caso de los alimentos étnicos  

Microsoft Academic Search

RESUMEN: El artículo investiga las actitudes de los consumidores hacia los alimentos nuevos mediante la escala FNS (Food Neo-phobia Scale). A partir de ella se obtiene el perfil de los individuos más y menos proclives a la introducción de nuevos alimentos en sus dietas, denominados respectivamente, «neo-fíli- cos» y «neo-fóbicos». Entre estos alimentos nuevos, los étnicos o propios de un

Dena M. Camarena; Ana I. Sanjuán

59

Remotely Operated Aircraft (ROA) Impact on the National Airspace System (NAS) Work Package: Automation Impacts of ROA's in the NAS  

NASA Technical Reports Server (NTRS)

The purpose of this document is to analyze the impact of Remotely Operated Aircraft (ROA) operations on current and planned Air Traffic Control (ATC) automation systems in the En Route, Terminal, and Traffic Flow Management domains. The operational aspects of ROA flight, while similar, are not entirely identical to their manned counterparts and may not have been considered within the time-horizons of the automation tools. This analysis was performed to determine if flight characteristics of ROAs would be compatible with current and future NAS automation tools. Improvements to existing systems / processes are recommended that would give Air Traffic Controllers an indication that a particular aircraft is an ROA and modifications to IFR flight plan processing algorithms and / or designation of airspace where an ROA will be operating for long periods of time.

2005-01-01

60

Comparison of GaInNAs and GaInNAsSb solar cells grown by plasma-assisted molecular beam epitaxy  

NASA Astrophysics Data System (ADS)

We compare dilute nitride GaInNAs and GaInNAsSb solar cells grown by molecular beam epitaxy. Single junction p-i-n diode solar cells were fabricated to test the dilute nitride and antimonide material fabrication process. Triple-junction solar cells were fabricated to test the behavior of single GaInNAs(Sb) junctions in multi-junction configuration. When nitrogen was added to the growth of GaInNAs, good crystal quality was maintained up to 4% of nitrogen at the used growth conditions. Short circuit current densities of the devices could be increased by adding Sb to the growth but at the same time the open circuit voltages decreased due to bandgap shrinkage induced by Sb. In multijunction configuration, the samples with Sb showed inferior properties to ones without it. Lower currents and voltages of Sb-containing cells may be linked to segregation of Sb and transfer to the upper junctions.

Aho, Arto; Tukiainen, Antti; Korpijärvi, Ville-Markus; Polojärvi, Ville; Salmi, Joel; Guina, Mircea

2012-10-01

61

Performance Characteristics of the Multi-Zone NAS Parallel Benchmarks  

NASA Technical Reports Server (NTRS)

We describe a new suite of computational benchmarks that models applications featuring multiple levels of parallelism. Such parallelism is often available in realistic flow computations on systems of grids, but had not previously been captured in bench-marks. The new suite, named NPB Multi-Zone, is extended from the NAS Parallel Benchmarks suite, and involves solving the application benchmarks LU, BT and SP on collections of loosely coupled discretization meshes. The solutions on the meshes are updated independently, but after each time step they exchange boundary value information. This strategy provides relatively easily exploitable coarse-grain parallelism between meshes. Three reference implementations are available: one serial, one hybrid using the Message Passing Interface (MPI) and OpenMP, and another hybrid using a shared memory multi-level programming model (SMP+OpenMP). We examine the effectiveness of hybrid parallelization paradigms in these implementations on three different parallel computers. We also use an empirical formula to investigate the performance characteristics of the multi-zone benchmarks.

Jin, Haoqiang; VanderWijngaart, Rob F.

2003-01-01

62

Structures of genes nasA and nasB, encoding assimilatory nitrate and nitrite reductases in Klebsiella pneumoniae M5al.  

PubMed Central

Klebsiella pneumoniae can use nitrate and nitrite as sole nitrogen sources during aerobic growth. Assimilatory nitrate and nitrite reductases convert nitrate through nitrite to ammonium. We report here the molecular cloning of the nasA and nasB genes, which encode assimilatory nitrate and nitrite reductase, respectively. These genes are tightly linked and probably form a nasBA operon. In vivo protein expression and DNA sequence analysis revealed that the nasA and nasB genes encode 92- and 104-kDa proteins, respectively. The NASA polypeptide is homologous to other prokaryotic molybdoenzymes, and the NASB polypeptide is homologous to eukaryotic and prokaryotic NADH-nitrite reductases. The narL gene product positively regulates expression of the structural genes for respiratory nitrate reductase, narGHJI. Surprisingly, we found that the nasBA operon is tightly linked to the narL-narGHJI region in K. pneumoniae, even though the nitrate assimilatory and respiratory enzymes serve different physiological functions. Images

Lin, J T; Goldman, B S; Stewart, V

1993-01-01

63

The NAS and The Histopathologic Diagnosis in NAFLD: Distinct Clinicopathologic Meanings  

PubMed Central

The diagnosis of nonalcoholic steatohepatitis (NASH) is defined by the presence and pattern of specific histological abnormalities on liver biopsy. A separate system of scoring the features of nonalcoholic fatty liver disease (NA) called the NAFLD Activity Score (NAS) was developed as a tool to measure changes in NAFLD during therapeutic trials. However, some studies have used threshold values of the NAS, specifically NAS ? 5, as a surrogate for the histologic diagnosis of NASH. To evaluate whether this unintended use of the NAS is valid, biopsy and clinical data from the 976 adults in NASH CRN studies were reviewed. Biopsies were evaluated centrally by the NASH CRN Pathology Committee. Definite steatohepatitis (SH) was diagnosed in 58.1%, borderline SH in 19.5% and “not SH” in 22%. The NAS was ? 5 in 50% and ? 4 in 49%; in this cohort only 75% of biopsies with definite SH had a NAS ? 5, while 28% of borderline SH and 7% of "not SH" biopsies had NAS ? 5. Of biopsies with a NAS ? 5, 86% had SH and 3% "not SH". NAS ? 4 did not indicate benign histology; 29% had SH and only 42% had "not SH". Higher values of the NAS were associated with higher levels of ALT and AST, while the diagnosis of SH was associated with features of the metabolic syndrome. Conclusions The diagnosis of definite SH or the absence of SH based on evaluation of patterns as well as individual lesions on liver biopsies does not always correlate with threshold values of the semiquantitative NAS. Clinical trials and observational studies should take these different performance characteristics into account.

Brunt, Elizabeth M.; Kleiner, David E.; Wilson, Laura A.; Belt, Patricia; Neuschwander-Tetri, Brent A.

2010-01-01

64

Looking Backward: Parting Reflections on Higher Education Reform from NAS's Founding President  

ERIC Educational Resources Information Center

Twenty-five years at the helm of the National Association of Scholars (NAS) have left the author with vivid memories: of knocks and bruises, peaks of exhilaration and, especially, unforgettable characters. But as for lessons learned, that's a very different story. In this article, the author shares some of the successes that happened in NAS for…

Balch, Stephen H.

2012-01-01

65

Natural Attenuation Software (NAS): A computer program for estimating remediation times of contaminated groundwater  

USGS Publications Warehouse

This paper describes the development and application of a modeling system called Natural Attenuation Software (NAS). NAS was designed as a screening tool to estimate times of remediation (TORs), associated with monitored natural attenuation (MNA), to lower groundwater contaminant concentrations to regulatory limits. Natural attenuation processes that NAS models include advection, dispersion, sorption, biodegradation, and non-aqueous phase liquid (NAPL) dissolution. This paper discusses the three main interactive components of NAS: 1) estimation of the target source concentration required for a plume extent to contract to regulatory limits, 2) estimation of the time required for NAFL contaminants in the source area to attenuate to a predetermined target source concentration, and 3) estimation of the time required for a plume extent to contract to regulatory limits after source reduction. The model's capability is illustrated by results from a case study at a MNA site, where NAS time of remediation estimates compared well with observed monitoring data over multiple years.

Mendez, E.; Widdowson, M.; Brauner, S.; Chapelle, F.; Casey, C.

2004-01-01

66

Computational Aeroscience at NAS and Future Trends in High Performance Computing  

NASA Technical Reports Server (NTRS)

NASA's Numerical Aerodynamic Simulation (NAS) program provides a unique world class supercomputing capability which is readily accessed by the U.S. aeronautics community and offers them the opportunity to perform high speed computations and simulations for a broad range of aerospace research applications. In addition, the NAS program performs on-going research and advanced technology development to ensure the innovative application of newly emerging technologies to computational fluid dynamics and other important aeroscience disciplines. The NAS system and its interaction with industry are described. Furthermore, the results of an analysis of current and future technologies and their potential impact on high performance computing are also presented.

Cooper, David M.

1994-01-01

67

Testing New Programming Paradigms with NAS Parallel Benchmarks  

NASA Technical Reports Server (NTRS)

Over the past decade, high performance computing has evolved rapidly, not only in hardware architectures but also with increasing complexity of real applications. Technologies have been developing to aim at scaling up to thousands of processors on both distributed and shared memory systems. Development of parallel programs on these computers is always a challenging task. Today, writing parallel programs with message passing (e.g. MPI) is the most popular way of achieving scalability and high performance. However, writing message passing programs is difficult and error prone. Recent years new effort has been made in defining new parallel programming paradigms. The best examples are: HPF (based on data parallelism) and OpenMP (based on shared memory parallelism). Both provide simple and clear extensions to sequential programs, thus greatly simplify the tedious tasks encountered in writing message passing programs. HPF is independent of memory hierarchy, however, due to the immaturity of compiler technology its performance is still questionable. Although use of parallel compiler directives is not new, OpenMP offers a portable solution in the shared-memory domain. Another important development involves the tremendous progress in the internet and its associated technology. Although still in its infancy, Java promisses portability in a heterogeneous environment and offers possibility to "compile once and run anywhere." In light of testing these new technologies, we implemented new parallel versions of the NAS Parallel Benchmarks (NPBs) with HPF and OpenMP directives, and extended the work with Java and Java-threads. The purpose of this study is to examine the effectiveness of alternative programming paradigms. NPBs consist of five kernels and three simulated applications that mimic the computation and data movement of large scale computational fluid dynamics (CFD) applications. We started with the serial version included in NPB2.3. Optimization of memory and cache usage was applied to several benchmarks, noticeably BT and SP, resulting in better sequential performance. In order to overcome the lack of an HPF performance model and guide the development of the HPF codes, we employed an empirical performance model for several primitives found in the benchmarks. We encountered a few limitations of HPF, such as lack of supporting the "REDISTRIBUTION" directive and no easy way to handle irregular computation. The parallelization with OpenMP directives was done at the outer-most loop level to achieve the largest granularity. The performance of six HPF and OpenMP benchmarks is compared with their MPI counterparts for the Class-A problem size in the figure in next page. These results were obtained on an SGI Origin2000 (195MHz) with MIPSpro-f77 compiler 7.2.1 for OpenMP and MPI codes and PGI pghpf-2.4.3 compiler with MPI interface for HPF programs.

Jin, H.; Frumkin, M.; Schultz, M.; Yan, J.

2000-01-01

68

Structural basis for proteasome formation controlled by an assembly chaperone nas2.  

PubMed

Proteasome formation does not occur due to spontaneous self-organization but results from a highly ordered process assisted by several assembly chaperones. The assembly of the proteasome ATPase subunits is assisted by four client-specific chaperones, of which three have been structurally resolved. Here, we provide the structural basis for the working mechanisms of the last, hereto structurally uncharacterized assembly chaperone, Nas2. We revealed that Nas2 binds to the Rpt5 subunit in a bivalent mode: the N-terminal helical domain of Nas2 masks the Rpt1-interacting surface of Rpt5, whereas its C-terminal PDZ domain caps the C-terminal proteasome-activating motif. Thus, Nas2 operates as a proteasome activation blocker, offering a checkpoint during the formation of the 19S ATPase prior to its docking onto the proteolytic 20S core particle. PMID:24685148

Satoh, Tadashi; Saeki, Yasushi; Hiromoto, Takeshi; Wang, Ying-Hui; Uekusa, Yoshinori; Yagi, Hirokazu; Yoshihara, Hidehito; Yagi-Utsumi, Maho; Mizushima, Tsunehiro; Tanaka, Keiji; Kato, Koichi

2014-05-01

69

Performance assessment of multijunction solar cells incorporating GaInNAsSb.  

PubMed

We have measured the characteristics of molecular beam epitaxy grown GaInNAsSb solar cells with different bandgaps using AM1.5G real sun illumination. Based on the solar cell diode characteristics and known parameters for state-of-the-art GaInP/GaAs and GaInP/GaAs/Ge cells, we have calculated the realistic potential efficiency increase for GaInP/GaAs/GaInNAsSb and GaInP/GaAs/GaInNAsSb/Ge multijunction solar cells for different current matching conditions. The analyses reveal that realistic GaInNAsSb solar cell parameters, render possible an extraction efficiency of over 36% at 1-sun AM1.5D illumination. PACS: 88.40.hj; 88.40.jm; 88.40.jp; 81.15.Hi. PMID:24498981

Aho, Arto; Tukiainen, Antti; Polojärvi, Ville; Guina, Mircea

2014-01-01

70

Unmanned Aircraft Systems (UAS) Integration in the National Airspace System (NAS) Project Subcommittee Final  

NASA Technical Reports Server (NTRS)

UAS Integration in the NAS Project overview with details from each of the subprojects. Subprojects include: Communications, Certification, Integrated Test and Evaluation, Human Systems Integration, and Separation Assurance/Sense and Avoid Interoperability.

Johnson, Chuck; Griner, James H.; Hayhurst, Kelly J.; Shively, Robert J.; Consiglio, Maria; Muller, Eric; Murphy, James; Kim, Sam

2012-01-01

71

Improved Optoelectronic Properties of Rapid Thermally Annealed Dilute Nitride GaInNAs Photodetectors  

NASA Astrophysics Data System (ADS)

We investigate the optical and electrical characteristics of GaInNAs/GaAs long-wavelength photodiodes grown under varying conditions by molecular beam epitaxy and subjected to postgrowth rapid thermal annealing (RTA) at a series of temperatures. It is found that the device performance of the nonoptimally grown GaInNAs p +- i- n + structures, with nominal compositions of 10% In and 3.8% N, can be improved significantly by the RTA treatment to match that of optimally grown structures. The optimally annealed devices exhibit overall improvement in optical and electrical characteristics, including increased photoluminescence brightness, reduced density of deep-level traps, reduced series resistance resulting from the GaAs/GaInNAs heterointerface, lower dark current, and significantly lower background doping density, all of which can be attributed to the reduced structural disorder in the GaInNAs alloy.

Tan, S. L.; Hunter, C. J.; Zhang, S.; Tan, L. J. J.; Goh, Y. L.; Ng, J. S.; Marko, I. P.; Sweeney, S. J.; Adams, A. R.; Allam, J.; David, J. P. R.

2012-12-01

72

Low temperature grown GaNAsSb: A promising material for photoconductive switch application  

SciTech Connect

We report a photoconductive switch using low temperature grown GaNAsSb as the active material. The GaNAsSb layer was grown at 200 °C by molecular beam epitaxy in conjunction with a radio frequency plasma-assisted nitrogen source and a valved antimony cracker source. The low temperature growth of the GaNAsSb layer increased the dark resistivity of the switch and shortened the carrier lifetime. The switch exhibited a dark resistivity of 10{sup 7} ? cm, a photo-absorption of up to 2.1 ?m, and a carrier lifetime of ?1.3 ps. These results strongly support the suitability of low temperature grown GaNAsSb in the photoconductive switch application.

Tan, K. H.; Yoon, S. F.; Wicaksono, S.; Loke, W. K.; Li, D. S. [School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore)] [School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); Saadsaoud, N.; Tripon-Canseliet, C. [Laboratoire d'Electronique et Electromagnétisme, Pierre and Marie Curie University, 4 Place Jussieu, 75005 Paris (France)] [Laboratoire d'Electronique et Electromagnétisme, Pierre and Marie Curie University, 4 Place Jussieu, 75005 Paris (France); Lampin, J. F.; Decoster, D. [Institute of Electronics, Microelectronics and Nanotechnology (IEMN), UMR CNRS 8520, Universite des Sciences et Technologies de Lille, BP 60069, 59652 Villeneuve d'Ascq Cedex (France)] [Institute of Electronics, Microelectronics and Nanotechnology (IEMN), UMR CNRS 8520, Universite des Sciences et Technologies de Lille, BP 60069, 59652 Villeneuve d'Ascq Cedex (France); Chazelas, J. [Thales Airborne Systems, 2 Avenue Gay Lussac, 78852 Elancourt (France)] [Thales Airborne Systems, 2 Avenue Gay Lussac, 78852 Elancourt (France)

2013-09-09

73

Activation of Rice nicotianamine synthase 2 (OsNAS2) enhances iron availability for biofortification.  

PubMed

Because micronutrients in human diets ultimately come from plant sources, malnutrition of essential minerals is a significant public health concern. By increasing the expression of nicotianamine synthase (NAS), we fortified the level of bioavailable iron in rice seeds. Activation of iron deficiency-inducible OsNAS2 resulted in a rise in Fe content (3.0-fold) in mature seeds. Its ectopic expression also increased that content. Enhanced expression led to higher tolerance of Fe deficiency and better growth under elevated pH. Mice fed with OsNAS2-D1 seeds recovered more rapidly from anemia, indicating that bioavailable Fe contents were improved by this increase in OsNAS2 expression. PMID:22228185

Lee, Sichul; Kim, You-Sun; Jeon, Un Sil; Kim, Yoon-Keun; Schjoerring, Jan K; An, Gynheung

2012-03-01

74

1.15?Å resolution structure of the proteasome-assembly chaperone Nas2 PDZ domain.  

PubMed

The 26S proteasome is a 2.5?MDa protease dedicated to the degradation of ubiquitinated proteins in eukaryotes. The assembly of this complex containing 66 polypeptides is assisted by at least nine proteasome-specific chaperones. One of these, Nas2, binds to the proteasomal AAA-ATPase subunit Rpt5. The PDZ domain of Nas2 binds to the C-terminal tail of Rpt5; however, it does not require the C-terminus of Rpt5 for binding. Here, the 1.15?Å resolution structure of the PDZ domain of Nas2 is reported. This structure will provide a basis for further insights regarding the structure and function of Nas2 in proteasome assembly. PMID:24699731

Singh, Chingakham R; Lovell, Scott; Mehzabeen, Nurjahan; Chowdhury, Wasimul Q; Geanes, Eric S; Battaile, Kevin P; Roelofs, Jeroen

2014-04-01

75

Molecular beam epitaxy grown GaNAsSb 1 eV photovoltaic cell  

Microsoft Academic Search

We report the performance of a 1 eV GaNAsSb-based photovoltaic cell grown using a molecular beam epitaxy system equipped with a radio frequency (RF) plasma-assisted nitrogen source. The 1 mum-thick photoabsorption layer contains 2% of N and 6% of Sb resulting in a GaNAsSb layer with bandgap energy of 1.0 eV. Under AM1.5G solar illumination condition with and without 850

K. H. Tan; S. Wicaksono; W. K. Loke; D. Li; S. F. Yoon; E. A. Fitzgerald; S. A. Ringel; J. S. Harris Jr.

2011-01-01

76

The NAS perchlorate review: questions remain about the perchlorate RfD.  

PubMed

Human exposure to perchlorate is commonplace because it is a contaminant of drinking water, certain foods, and breast milk. The U.S. Environmental Protection Agency (EPA) conducted a perchlorate risk assessment in 2002 that yielded a reference dose (RfD) based on both the animal and human toxicology data. This assessment has been superceded by a recent National Academy of Science (NAS) review that derived a perchlorate RfD that is 20-fold greater (less stringent) than that derived by the U.S. EPA in 2002. The NAS-derived RfD was put on the U.S. EPA's Integrated Risk Information System (IRIS) database very quickly and with no further public review. In this commentary we raise concerns about the NAS approach to RfD development in three areas of toxicity assessment: the dose that the NAS described as a no observable adverse-effect level is actually associated with perchlorate-induced effects; consideration of uncertainties was insufficient; and the NAS considered the inhibition of iodine uptake to be a nonadverse effect. We conclude that risk assessors should carefully evaluate whether the IRIS RfD is the most appropriate value for assessing perchlorate risk. PMID:16140613

Ginsberg, Gary; Rice, Deborah

2005-09-01

77

UAS in the NAS: Survey Responses by ATC, Manned Aircraft Pilots, and UAS Pilots  

NASA Technical Reports Server (NTRS)

NASA currently is working with industry and the Federal Aviation Administration (FAA) to establish future requirements for Unmanned Aircraft Systems (UAS) flying in the National Airspace System (NAS). To work these issues NASA has established a multi-center UAS Integration in the NAS project. In order to establish Ground Control Station requirements for UAS, the perspective of each of the major players in NAS operations was desired. Three on-line surveys were administered that focused on Air Traffic Controllers (ATC), pilots of manned aircraft, and pilots of UAS. Follow-up telephone interviews were conducted with some survey respondents. The survey questions addressed UAS control, navigation, and communications from the perspective of small and large unmanned aircraft. Questions also addressed issues of UAS equipage, especially with regard to sense and avoid capabilities. From the ATC and military ATC perspective, of particular interest is how mixed-operations (manned/UAS) have worked in the past and the role of aircraft equipage. Knowledge gained from this information is expected to assist the NASA UAS in the NAS project in directing research foci thus assisting the FAA in the development of rules, regulations, and policies related to UAS in the NAS.

Comstock, James R., Jr.; McAdaragh, Raymon; Ghatas, Rania W.; Burdette, Daniel W.; Trujillo, Anna C.

2013-01-01

78

UAS in the NAS: Survey Responses by ATC, Manned Aircraft Pilots, and UAS Pilots  

NASA Technical Reports Server (NTRS)

NASA currently is working with industry and the Federal Aviation Administration (FAA) to establish future requirements for Unmanned Aircraft Systems (UAS) flying in the National Airspace System (NAS). To work these issues NASA has established a multi-center "UAS Integration in the NAS" project. In order to establish Ground Control Station requirements for UAS, the perspective of each of the major players in NAS operations was desired. Three on-line surveys were administered that focused on Air Traffic Controllers (ATC), pilots of manned aircraft, and pilots of UAS. Follow-up telephone interviews were conducted with some survey respondents. The survey questions addressed UAS control, navigation, and communications from the perspective of small and large unmanned aircraft. Questions also addressed issues of UAS equipage, especially with regard to sense and avoid capabilities. From the civilian ATC and military ATC perspectives, of particular interest are how mixed operations (manned / UAS) have worked in the past and the role of aircraft equipage. Knowledge gained from this information is expected to assist the NASA UAS Integration in the NAS project in directing research foci thus assisting the FAA in the development of rules, regulations, and policies related to UAS in the NAS.

Comstock, James R., Jr.; McAdaragh, Raymon; Ghatas, Rania W.; Burdette, Daniel W.; Trujillo, Anna C.

2014-01-01

79

Molecular beam epitaxy grown GaNAsSb 1 eV photovoltaic cell  

NASA Astrophysics Data System (ADS)

We report the performance of a 1 eV GaNAsSb-based photovoltaic cell grown using a molecular beam epitaxy system equipped with a radio frequency (RF) plasma-assisted nitrogen source. The 1 ?m-thick photoabsorption layer contains 2% of N and 6% of Sb resulting in a GaNAsSb layer with bandgap energy of 1.0 eV. Under AM1.5G solar illumination condition with and without 850 nm long pass filter, the GaNAsSb-based photovoltaic cell demonstrates a JSC values of 15 and 32 mA/W, respectively. Deep level transient spectroscopy analysis reveals that the VOC of the photovoltaic cell could possibly be limited by the presence of arsenic antisite defects.

Tan, K. H.; Wicaksono, S.; Loke, W. K.; Li, D.; Yoon, S. F.; Fitzgerald, E. A.; Ringel, S. A.; Harris, J. S., Jr.

2011-11-01

80

GaNAsSb material for ultrafast microwave photoconductive switching application  

NASA Astrophysics Data System (ADS)

We report a photoconductive switch with GaNAsSb as active material for microwave switching application. The GaNAsSb layer was grown by molecular beam epitaxy in conjunction with a rf plasma-assisted nitrogen source and a valved antimony cracker source. The 0.5 ?m thick GaNAsSb photoabsorption layer contains 3.5% of N and 9% of Sb. The switch exhibits pulsed response with full width at half maximum of 30 ps and photoresponse of up to 1.6 ?m. In microwave switching application, the switch shows ON/OFF ratio of 11 dB at 1 GHz and response up to 15 GHz.

Tan, K. H.; Yoon, S. F.; Tripon-Canseliet, C.; Loke, W. K.; Wicaksono, S.; Faci, S.; Saadsaoud, N.; Lampin, J. F.; Decoster, D.; Chazelas, J.

2008-08-01

81

GaNAsP: An intermediate band semiconductor grown by gas-source molecular beam epitaxy  

NASA Astrophysics Data System (ADS)

Dilute nitride GaNAsP thin films were grown via a GaAsP metamorphic buffer on GaP(100) substrate with gas-source molecular beam epitaxy. The compositions of this III-V-V-V compound were determined by channeling Rutherford backscattering spectroscopy and nuclear reaction analysis. Photoreflectance shows two distinctive transitions from the valence band to the split conduction bands due to N incorporation. Photoluminescence and optical absorption show the fundamental bandgap of Ga(N)AsP is largely tailored by the small amount of N. The observed multiband characteristics and the bandgap tunability of GaNAsP are two merits that fit into the intermediate-band solar cell roadmap, and GaNAsP of high crystal quality provides a strong candidate for intermediate band solar cell materials.

Kuang, Y. J.; Yu, K. M.; Kudrawiec, R.; Luce, A. V.; Ting, M.; Walukiewicz, W.; Tu, C. W.

2013-03-01

82

Molecular beam epitaxy grown GaNAsSb 1 eV photovoltaic cell  

Microsoft Academic Search

We report the performance of a 1eV GaNAsSb-based photovoltaic cell grown using a molecular beam epitaxy system equipped with a radio frequency (RF) plasma-assisted nitrogen source. The 1?m-thick photoabsorption layer contains 2% of N and 6% of Sb resulting in a GaNAsSb layer with bandgap energy of 1.0eV. Under AM1.5G solar illumination condition with and without 850nm long pass filter,

K. H. Tan; S. Wicaksono; W. K. Loke; D. Li; S. F. Yoon; E. A. Fitzgerald; S. A. Ringel; J. S. Harris Jr.

2011-01-01

83

GaInNAsSb\\/GaAs Photodiodes for Long-Wavelength Applications  

Microsoft Academic Search

GaInNAsSb p-i-n photodetectors on GaAs substrates capable of detecting wavelengths up to 1550 nm with a re- duced dark current are presented in this letter. Responsivities of 0.18 A\\/W at 1300 nm and 0.098 A\\/W at 1550 nm were achieved in devices with a ? 0.5-?m-thick GaInNAsSb p-i-n epitaxial layer with 10% In, 4.08% N, and 4.4% Sb. The absorption

Siew Li Tan; Shiyong Zhang; Wai Mun Soong; Yu Ling Goh; Lionel J. J. Tan; Jo Shien Ng; John P. R. David; Igor P. Marko; Alfred R. Adams; Stephen J. Sweeney; Jeremy Allam

2011-01-01

84

General Nitrogen Regulation of Nitrate Assimilation Regulatory Gene nasR Expression in Klebsiella oxytoca M5al  

PubMed Central

Klebsiella oxytoca can assimilate nitrate and nitrite by using enzymes encoded by the nasFEDCBA operon. Expression of the nasF operon is controlled by general nitrogen regulation (Ntr) via the NtrC transcription activator and by pathway-specific nitrate and nitrite induction via the NasR transcription antiterminator. This paper reports our analysis of nasR gene expression. We constructed strains bearing single-copy ?(nasR-lacZ) operon fusions within the chromosomal rhaBAD-rhaSR locus. The expression of ?rhaBS::[?(nasR-lacZ)] operon fusions was induced about 10-fold during nitrogen-limited growth. Induction was reduced in both ntrC and rpoN null mutants, indicating that Ntr control of nasR gene expression requires the NtrC and ?N (?54) proteins. Sequence inspection of the nasR control region reveals an apparent ?N-dependent promoter but no apparent NtrC protein binding sites. Analysis of site-specific mutations coupled with primer extension analysis authenticated the ?N-dependent nasR promoter. Fusion constructs with only about 70 nucleotides (nt) upstream of the transcription initiation site exhibited patterns of ?-galactosidase expression indistinguishable from ?(nasR-lacZ) constructs with about 470 nt upstream. Expression was independent of the Nac protein, implying that NtrC is a direct activator of nasR transcription. Together, these results indicate that nasR gene expression does not require specific upstream NtrC-binding sequences, as previously noted for argT gene expression in Salmonella typhimurium (G. Schmitz, K. Nikaido, and G. F.-L. Ames, Mol. Gen. Genet. 215:107–117, 1988).

Wu, Stephen Qitu; Chai, Weihang; Lin, Janine T.; Stewart, Valley

1999-01-01

85

Beyond the NAS Parallel Benchmarks: Measuring Dynamic Program Performance and Grid Computing Applications  

NASA Technical Reports Server (NTRS)

The contents include: 1) A brief history of NPB; 2) What is (not) being measured by NPB; 3) Irregular dynamic applications (UA Benchmark); and 4) Wide area distributed computing (NAS Grid Benchmarks-NGB). This paper is presented in viewgraph form.

VanderWijngaart, Rob F.; Biswas, Rupak; Frumkin, Michael; Feng, Huiyu; Biegel, Bryan (Technical Monitor)

2001-01-01

86

Comparison of Origin 2000 and Origin 3000 Using NAS Parallel Benchmarks  

NASA Technical Reports Server (NTRS)

This report describes results of benchmark tests on the Origin 3000 system currently being installed at the NASA Ames National Advanced Supercomputing facility. This machine will ultimately contain 1024 R14K processors. The first part of the system, installed in November, 2000 and named mendel, is an Origin 3000 with 128 R12K processors. For comparison purposes, the tests were also run on lomax, an Origin 2000 with R12K processors. The BT, LU, and SP application benchmarks in the NAS Parallel Benchmark Suite and the kernel benchmark FT were chosen to determine system performance and measure the impact of changes on the machine as it evolves. Having been written to measure performance on Computational Fluid Dynamics applications, these benchmarks are assumed appropriate to represent the NAS workload. Since the NAS runs both message passing (MPI) and shared-memory, compiler directive type codes, both MPI and OpenMP versions of the benchmarks were used. The MPI versions used were the latest official release of the NAS Parallel Benchmarks, version 2.3. The OpenMP versiqns used were PBN3b2, a beta version that is in the process of being released. NPB 2.3 and PBN 3b2 are technically different benchmarks, and NPB results are not directly comparable to PBN results.

Turney, Raymond D.

2001-01-01

87

Analysis of Depletion-Region Collection in GalanNAs Solar Cells.  

National Technical Information Service (NTIS)

We provide qualitative insight into depletion-region collection in GaInNAs cells to (1) understand the effect of diffusion length L on the QE; and (2) describe the magnitude of L required to get adequate current from the cell. We use Wolf's equations for ...

D. J. Friedman A. J. Ptak S. R. Kurtz J. F. Geisz

2005-01-01

88

MPI versus MPI+OpenMP on IBM SP for the NAS benchmarks  

Microsoft Academic Search

The hybrid memory model of clusters of multiprocessors raises two issues: programming model and performance. Many parallel programs have been written by using the MPI standard. To evaluate the pertinence of hybrid models for existing MPI codes, we compare a unified model (MPI) and a hybrid one (OpenMP fine grain parallelization after profiling) for the NAS 2.3 benchmarks on two

Franck Cappello; Daniel Etiemble

2000-01-01

89

Nonequilibrium gain in optically pumped GaInNAs laser structures.  

SciTech Connect

A theory is presented which couples a dynamical laser model to a fully microscopic calculation of scattering effects. Calculations for two optically pumped GaInNAs laser structures show how this approach can be used to analyze nonequilibrium and dynamical laser properties over a wide range of system parameters.

Becker, Stanley Edward (Philipps-University Marburg, Marburg, Germany); Thranhardt, A. (Philipps-University Marburg, Marburg, Germany); Hader, J. (University of Arizona, Tucson, Arizona); Schlichenmaier, C. (Philipps-University Marburg, Marburg, Germany); Koch, Stephan W. (Philipps-University Marburg, Marburg, Germany); Chow, Weng Wah; Meier, Torsten. (Philipps-University Marburg, Marburg, Germany); Moloney, Jerome V. (University of Arizona, Tucson, Arizona); Kuznetsova, I. (Philipps-University Marburg, Marburg, Germany)

2004-11-01

90

National Airspace System: Air Traffic Control and Airspace Management Operational Concept, NAS-SR-132.  

National Technical Information Service (NTIS)

The NAS has a responsibility to assist in the safe and efficient flow of traffic from departure aerodrome (or entrance to the system) to destination aerodrome (or exit from the system). It provides flight control services in the en route, terminal, and oc...

W. Trent, T. Pickerell, H. Nelson

1992-01-01

91

National Airspace System: Air Traffic Control and Airspace Management Operational Concept NAS-SR-132.  

National Technical Information Service (NTIS)

The NAS has a responsibility to assist in the safe and efficient flow of traffic from departure aerodrome (or entrance to the system) to destination aerodrome (or exit from the system). It provides flight control services in the en route, terminal, and oc...

W. Trent, T. Pickerell, H. Nelson

1992-01-01

92

Thick lattice-matched GaInNAs films in photodetector applications  

NASA Astrophysics Data System (ADS)

The dilute-nitride GaInNAs shows great promise in becoming the next choice for long-wavelength (0.9 to 1.6 ?m) photodetector applications due to the ability for it to be grown lattice-matched on GaAs substrates. GaAs-based devices have several advantages over InP-based devices, such as substrate cost, convenience of processing, and optoelectronic band parameters. This paper will present results from the first high-quality thick GaInNAs films grown by solid state molecular beam epitaxy with a nitrogen plasma source and the first high efficiency photodetectors which have been fabricated from those materials. GaInNAs films up to 2 microns thick have been grown coherently on GaAs substrates. These films exhibit reasonable photoluminescence intensities at peak wavelengths of 1.22 to 1.13 ?m before and after a rapid thermal anneal at a series of temperatures. PIN photodiodes with these thick GaInNAs films in the intrinsic regions show responsivity (better than 0.5 A/W at 1.064 ?m), dark current (200 nA at -2 V), and signal-to-noise ratio (greater than 105) approaching those of commercially available InGaAs/InP devices. Furthermore, it will be shown that these devices show significantly lower dark current and higher signal-to-noise ratio than similar metamorphic InGaAs/GaAs structures.

Jackrel, David; Yuen, Homan; Bank, Seth; Wistey, Mark; Fu, Junxian; Yu, Xiaojun; Rao, Zhilong; Harris, James S.

2005-04-01

93

Production Technology of beta-Alumina Ceramics for NA/S Batteries.  

National Technical Information Service (NTIS)

Fabrication processes to produce tubes of beta-alumina ceramics for use in Na/S batteries were defined. The selection of raw materials, the handling of the beta-alumina powders, and development of a shaping technique were considered. Parameters for spray ...

G. Heimke G. Willmann

1979-01-01

94

Meeting of Experts on NASA's Unmanned Aircraft System (UAS) Integration in the National Airspace Systems (NAS) Project  

NASA Technical Reports Server (NTRS)

Topics discussed include: Aeronautics Research Mission Directorate Integrated Systems Research Program (ISRP) and UAS Integration in the NAS Project; UAS Integration into the NAS Project; Separation Assurance and Collision Avoidance; Pilot Aircraft Interface Objectives/Rationale; Communication; Certification; and Integrated Tests and Evaluations.

Wolfe, Jean; Bauer, Jeff; Bixby, C.J.; Lauderdale, Todd; Shively, Jay; Griner, James; Hayhurst, Kelly

2010-01-01

95

Avaliação das normas de biossegurança nas clínicas odonto- lógicas da UFPE Evaluation of biosecutrity norms in UFPE dental clinics  

Microsoft Academic Search

Key-words O objetivo deste trabalho foi observar o cumprimento das normas de biossegurança e os cuidados com os riscos ocupacionais pelos alunos que atenderam nas clínicas de Odontologia Preventiva, Odontopediatria, Dentística, Endodontia e nos procedimentos cirúrgicos nas clínicas de Periodontia e Cirurgia, da Faculdade de Odontologia da Universidade Federal de Pernambuco. Este trabalho consistiu em um estudo observacional, no qual

Márcia Maria; Vendiciano Barbosa Vasconcelos; Catarina da Mot; Vasconcelos Brasi; Cláudia Cristina; Brainer de Oliveira Mot; Rabelo de Carvalho

96

Quantitative chemical evaluation of dilute GaNAs using ADF STEM: avoiding surface strain induced artifacts.  

PubMed

The high angle annular dark field intensity (HAADF) in scanning transmission electron microscopy (STEM) can be used for a quantitative evaluation of the chemical composition in dilute GaNAs quantum wells by comparison with simulated intensities. As the scattered intensity is highly sensitive to surface strain fields originating from the quantum wells embedded in GaAs, the HAADF intensity is difficult to evaluate in a quantitative way as long as strain contrast cannot be distinguished from chemical contrast. We present a method to achieve full 2D HAADF STEM compositional mapping of GaNAs/GaAs quantum well systems by making use of information from two different camera lengths. PMID:23542584

Grieb, Tim; Müller, Knut; Fritz, Rafael; Grillo, Vincenzo; Schowalter, Marco; Volz, Kerstin; Rosenauer, Andreas

2013-06-01

97

GlnR positively regulates nasA transcription in Streptomyces coelicolor.  

PubMed

The model actinomycete, Streptomyces coelicolor is able to grow with nitrate as the sole nitrogen source. In this study, an assimilatory nitrate reductase encoding gene, nasA (SCO2473) was, for the first time, identified from the genome of S. coelicolor by genetic and physiological means. We also proved that GlnR, a previously characterized global nitrogen regulator in S. coelicolor, positively regulated the transcription of nasA via specific binding to a cis-element similar but different from the previously characterized consensus sequence. This finding will certainly facilitate the better understanding about both the functional scope and the mechanism of action of GlnR in regulating nitrogen metabolism in S. coelicolor. PMID:19501565

Wang, Jin; Zhao, Guo-Ping

2009-08-14

98

1.31-?m GaInNAs lasers fabricated with pulsed anodic oxidation  

NASA Astrophysics Data System (ADS)

Semiconductor lasers at wavelengths around 1.3?m are widely used for optic communications. For GaInNAs, the incorporation of nitrogen in the active layer can reduce the band-gap energy and allow emission wavelengths as long as 1.3?m. Ridge waveguide GaInNAs strain single-quantum-well lasers were fabricated with pulsed anodic oxidation (PAO). Using the technology PAO, we prevented the damage from the ion bombardment in the procedure of sputtering silicon dioxide used for building the insulating film. The output power of the laser with a wavelength of 1.31?m reached 14mW in CW mode at room temperature. The threshold-current was 18mA and its density was 360A/cm2. The characteristic temperature of lasers was 135.1K and the quantum efficiency reached 76%.

Deng, Yun; Qu, Yi; Qiao, Zhongliang; Zou, Huimin; Wang, Yuming; Li, Zhanguo

2008-03-01

99

Photoreflectance Investigations of Temperature Dependence of the ``Different'' Energy Gaps in GaInNAs Compounds  

NASA Astrophysics Data System (ADS)

In this paper, we report photoreflectance investigations of GaInNAs layers almost lattice-matched to GaAs substrate and annealed at different temperatures. Our investigations done from 10 K to room temperature give evidence that these layers exhibit several distinct band gaps. These distinct band gaps, which were found to co-exist, are associated with different nitrogen bonding configurations (N-Ga4-mInm (0<= m <=4) short-range-order clusters). The annealing-induced blueshift of GaInNAs band gap energy, which is usually observed in this system, is due to the change in the intensity of PR resonances related to different N-Ga4-mInm configurations.

Kudrawiec, R.; Misiewicz, J.; Pavelescu, E.-M.; Konttinen, J.; Pessa, M.

2005-06-01

100

Nonexponential photoluminescence transients in a Ga(NAsP) lattice matched to a (001) silicon substrate  

NASA Astrophysics Data System (ADS)

Ga(NAsP) grown lattice-matched on (001) silicon substrate is a very promising material for future integrated, electrically pumped lasers on silicon. Here, we present experimental and theoretical studies of the time-resolved photoluminescence in Ga(NAsP)/Si quantum well structures. The experimental results obtained at 10 K show a strong nonexponential transient behavior for the photoluminescence signal. A detailed comparison with theoretical calculations based on rate equations and on straightforward Monte Carlo simulations reveals that this effect is controlled by an interplay between the fast capture of carriers on nonradiative centers and the slow radiative recombination via localized states. We demonstrate that the measurement of the time-resolved photoluminescence can serve as a convenient tool for estimating the relative concentrations of nonradiative and radiative centers in compound materials.

Jandieri, K.; Kunert, B.; Liebich, S.; Zimprich, M.; Volz, K.; Stolz, W.; Gebhard, F.; Baranovskii, S. D.; Koukourakis, N.; Gerhardt, N. C.; Hofmann, M. R.

2013-01-01

101

Object-Oriented Implementation of the NAS Parallel Benchmarks using Charm++  

NASA Technical Reports Server (NTRS)

This report describes experiences with implementing the NAS Computational Fluid Dynamics benchmarks using a parallel object-oriented language, Charm++. Our main objective in implementing the NAS CFD kernel benchmarks was to develop a code that could be used to easily experiment with different domain decomposition strategies and dynamic load balancing. We also wished to leverage the object-orientation provided by the Charm++ parallel object-oriented language, to develop reusable abstractions that would simplify the process of developing parallel applications. We first describe the Charm++ parallel programming model and the parallel object array abstraction, then go into detail about each of the Scalar Pentadiagonal (SP) and Lower/Upper Triangular (LU) benchmarks, along with performance results. Finally we conclude with an evaluation of the methodology used.

Krishnan, Sanjeev; Bhandarkar, Milind; Kale, Laxmikant V.

1996-01-01

102

Room temperature continuous-wave operation of GaInNAs long wavelength VCSELs  

Microsoft Academic Search

Vertical cavity surface-emitting lasers (VCSELs) are becoming increasingly important for short-haul optical fiber transmission systems. Given the commercial success of GaAs-based 850 nm VCSELs, dramatic enhancements in transmission bandwidth and distance can be achieved in conventional single- and multi-mode fiber by extending the emission wavelength to the 1300 nm-1550 nm range. GaInNAs is a promising active layer material grown on

M. C. Larson; C. W. Coldren; S. G. Spruytte; H. E. Petersen; J. S. Harris

2000-01-01

103

Applications Performance Under MPL and MPI on NAS IBM SP2  

NASA Technical Reports Server (NTRS)

On July 5, 1994, an IBM Scalable POWER parallel System (IBM SP2) with 64 nodes, was installed at the Numerical Aerodynamic Simulation (NAS) Facility Each node of NAS IBM SP2 is a "wide node" consisting of a RISC 6000/590 workstation module with a clock of 66.5 MHz which can perform four floating point operations per clock with a peak performance of 266 Mflop/s. By the end of 1994, 64 nodes of IBM SP2 will be upgraded to 160 nodes with a peak performance of 42.5 Gflop/s. An overview of the IBM SP2 hardware is presented. The basic understanding of architectural details of RS 6000/590 will help application scientists the porting, optimizing, and tuning of codes from other machines such as the CRAY C90 and the Paragon to the NAS SP2. Optimization techniques such as quad-word loading, effective utilization of two floating point units, and data cache optimization of RS 6000/590 is illustrated, with examples giving performance gains at each optimization step. The conversion of codes using Intel's message passing library NX to codes using native Message Passing Library (MPL) and the Message Passing Interface (NMI) library available on the IBM SP2 is illustrated. In particular, we will present the performance of Fast Fourier Transform (FFT) kernel from NAS Parallel Benchmarks (NPB) under MPL and MPI. We have also optimized some of Fortran BLAS 2 and BLAS 3 routines, e.g., the optimized Fortran DAXPY runs at 175 Mflop/s and optimized Fortran DGEMM runs at 230 Mflop/s per node. The performance of the NPB (Class B) on the IBM SP2 is compared with the CRAY C90, Intel Paragon, TMC CM-5E, and the CRAY T3D.

Saini, Subhash; Simon, Horst D.; Lasinski, T. A. (Technical Monitor)

1994-01-01

104

Functional Requirements Document for HALE UAS Operations in the NAS: Step 1. Version 3  

NASA Technical Reports Server (NTRS)

The purpose of this Functional Requirements Document (FRD) is to compile the functional requirements needed to achieve the Access 5 Vision of "operating High Altitude, Long Endurance (HALE) Unmanned Aircraft Systems (UAS) routinely, safely, and reliably in the national airspace system (NAS)" for Step 1. These functional requirements could support the development of a minimum set of policies, procedures and standards by the Federal Aviation Administration (FAA) and various standards organizations. It is envisioned that this comprehensive body of work will enable the FAA to establish and approve regulations to govern safe operation of UAS in the NAS on a routine or daily "file and fly" basis. The approach used to derive the functional requirements found within this FRD was to decompose the operational requirements and objectives identified within the Access 5 Concept of Operations (CONOPS) into the functions needed to routinely and safely operate a HALE UAS in the NAS. As a result, four major functional areas evolved to enable routine and safe UAS operations for an on-demand basis in the NAS. These four major functions are: Aviate, Navigate, Communicate, and Avoid Hazards. All of the functional requirements within this document can be directly traceable to one of these four major functions. Some functions, however, are traceable to several, or even all, of these four major functions. These cross-cutting functional requirements support the "Command / Control: function as well as the "Manage Contingencies" function. The requirements associated to these high-level functions and all of their supporting low-level functions are addressed in subsequent sections of this document.

2006-01-01

105

Temperature Dependence of Photoluminescence Peak Energy in Ga(In)NAs  

NASA Astrophysics Data System (ADS)

Introducing normal coordinate system, theoretical approach to band gap alteration with temperature is described. The derived expression is applied to a GaNAs system having the nitrogen composition of about 1.4%. It is found that the band gap narrowing in this system is originated in the inter-band mixing assisted by an LO phonon at a ? point through electron--phonon interaction.

Emura, Shuichi; Nakamoto, Hiroki; Ishikawa, Fumitaro; Kondow, Masahiko; Asahi, Hajime

2011-12-01

106

NAS Parallel Benchmarks I/O Version 2.4. 2.4  

NASA Technical Reports Server (NTRS)

We describe a benchmark problem, based on the Block-Tridiagonal (BT) problem of the NAS Parallel Benchmarks (NPB), which is used to test the output capabilities of high-performance computing systems, especially parallel systems. We also present a source code implementation of the benchmark, called NPBIO2.4-MPI, based on the MPI implementation of NPB, using a variety of ways to write the computed solutions to file.

Wong, Parkson; VanderWijngaart, Rob F.; Biegel, Bryan A. (Technical Monitor)

2002-01-01

107

Unmanned Aircraft Systems (UAS) Integration in the National Airspace System (NAS) Project  

NASA Technical Reports Server (NTRS)

NASA's UAS Integration in the NAS project, has partnered with Rockwell Collins to develop a concept Control and Non-Payload Communication system prototype radio, operating on recently allocated UAS frequency spectrum bands. The prototype radio will be used to validate initial proposed performance requirements for UAS control communications. This presentation will give an overview of the current status of the design, development, and flight test planning for this prototype radio.

Griner, James H.

2013-01-01

108

The effect of metal sulfides in the cathode on Na\\/S battery performance  

Microsoft Academic Search

The effect of metal sulfides in the cathode on Na\\/S battery performance was investigated. Battery capacity was heavily decreased by doping with FeS2, CoS2 and Cr2S3, and little influenced by doping with NiS2 and Al2S3. A FeS2 3.0wt.% doped cell exhibited a 65% resistance rise and a 65% capacity loss during cycling. Such a degradation causing by the metal sulfides

Ryoichi Okuyama; Hiroharu Nakashima; Toshio Sano; Eiichi Nomura

2001-01-01

109

The OpenMP Implementation of NAS Parallel Benchmarks and Its Performance  

Microsoft Academic Search

As the new ccNUMA architecture became popular in recent years, parallel programming with compiler directives on these machines has evolved to accommodate new needs. In this study, we examine the effectiveness of OpenMP directives for parallelizing the NAS Parallel Benchmarks. Implementation details will be discussed and p erformance will be compared with the MPI implementation. We have demonstrated that OpenMP

H. Jin; M. Frumkin; J. Yan

1999-01-01

110

Nitrogen incorporation effects on gain properties of GaInNAs lasers : experiment and theory.  

SciTech Connect

Gain properties of GaInNAs lasers with different nitrogen concentrations in the quantum wells are investigated experimentally and theoretically. Whereas nitrogen incorporation induces appreciable modifications in the spectral extension and the carrier density dependence of the gain, it is found that the linewidth enhancement factor is reduced by inclusion of nitrogen, but basically unaffected by different nitrogen content due to the balancing between gain and index changes.

Thranhardt, A. (Fachbereich Physik, Marburg, Germany); Mawst, L. J. (University of Wisconsin-Madison, Madison, WI); Hader, J. (University of Arizona, Tucson, AZ); Schlichenmaier, C. (Fachbereich Physik, Marburg, Germany); Tansu, N. (Lehigh Unversity, Bethlehem, PA); Yeh, J. -Y. (University of Wisconsin-Madison, Madison, WI); Belenky, G. (State University of New York at Stony Brook, Stony Brook, NY); Chow, Weng Wah; Shterengas, L. (State University of New York at Stony Brook, Stony Brook, NY); Moloney, Jerome V. (University of Arizona, Tucson, AZ); Koch, S. W. (Fachbereich Physik, Marburg, Germany); Kuznetsova, I. (Fachbereich Physik, Marburg, Germany)

2005-05-01

111

NAS technical summaries: Numerical aerodynamic simulation program, March 1991 - February 1992  

NASA Technical Reports Server (NTRS)

NASA created the Numerical Aerodynamic Simulation (NAS) Program in 1987 to focus resources on solving critical problems in aeroscience and related disciplines by utilizing the power of the most advanced supercomputers available. The NAS Program provides scientists with the necessary computing power to solve today's most demanding computational fluid dynamics problems and serves as a pathfinder in integrating leading-edge supercomputing technologies, thus benefiting other supercomputer centers in Government and industry. This report contains selected scientific results from the 1991-92 NAS Operational Year, March 4, 1991 to March 3, 1992, which is the fifth year of operation. During this year, the scientific community was given access to a Cray-2 and a Cray Y-MP. The Cray-2, the first generation supercomputer, has four processors, 256 megawords of central memory, and a total sustained speed of 250 million floating point operations per second. The Cray Y-MP, the second generation supercomputer, has eight processors and a total sustained speed of one billion floating point operations per second. Additional memory was installed this year, doubling capacity from 128 to 256 megawords of solid-state storage-device memory. Because of its higher performance, the Cray Y-MP delivered approximately 77 percent of the total number of supercomputer hours used during this year.

1992-01-01

112

Role of arsenic hexagonal growth-suppression on a cubic GaNAs growth using metalorganic chemical vapor deposition  

SciTech Connect

The hexagonal domain suppression-effects in cubic-GaNAs grown by metalorganic chemical-vapor deposition (MOCVD) is reported. A thin buffer layer (20 nm) was first grown on a substrate at 853 K using trimethylgallium and dimethylhydrazine (DMHy), and GaNAs samples were grown at different AsH{sub 3} flow rates (0 {approximately} 450 {micro}mol/min) at 1,193 K. As a result, three types of surface morphologies were obtained: the first was a smooth surface (AsH{sub 3} = 0 {micro}mol/min); and the third involved three-dimensional surface morphologies (above 450 {micro}mol/min of AsH{sub 3} flow rate). Furthermore, it was confirmed using X-ray diffraction that the mixing ratio of hexagonal GaNAs in cubic GaNAs decreased with an increase of the AsH{sub 3} flow rate. The authors could obtain GaNAs having a cubic component of above 85% at AsH{sub 3} flow rates above 20 {micro}mol/min. Therefore, the MOCVD growth method using AsH{sub 3} and DMHy was mostly effective for suppressing hexagonal GaNAs. It was observed that the photoluminescence intensity of GaNAs was decreased with increase of arsine flow rate.

Yoshida, S.; Kimura, T.; Wu, J.; Kikawa, J.; Onabe, K.; Shiraki, Y.

2000-07-01

113

Nitrogen and oxygen regulation of Bacillus subtilis nasDEF encoding NADH-dependent nitrite reductase by TnrA and ResDE.  

PubMed

The nitrate and nitrite reductases of Bacillus subtilis have two different physiological functions. Under conditions of nitrogen limitation, these enzymes catalyze the reduction of nitrate via nitrite to ammonia for the anabolic incorporation of nitrogen into biomolecules. They also function catabolically in anaerobic respiration, which involves the use of nitrate and nitrite as terminal electron acceptors. Two distinct nitrate reductases, encoded by narGHI and nasBC, function in anabolic and catabolic nitrogen metabolism, respectively. However, as reported herein, a single NADH-dependent, soluble nitrite reductase encoded by the nasDE genes is required for both catabolic and anabolic processes. The nasDE genes, together with nasBC (encoding assimilatory nitrate reductase) and nasF (required for nitrite reductase siroheme cofactor formation), constitute the nas operon. Data presented show that transcription of nasDEF is driven not only by the previously characterized nas operon promoter but also from an internal promoter residing between the nasC and nasD genes. Transcription from both promoters is activated by nitrogen limitation during aerobic growth by the nitrogen regulator, TnrA. However, under conditions of oxygen limitation, nasDEF expression and nitrite reductase activity were significantly induced. Anaerobic induction of nasDEF required the ResDE two-component regulatory system and the presence of nitrite, indicating partial coregulation of NasDEF with the respiratory nitrate reductase NarGHI during nitrate respiration. PMID:9765565

Nakano, M M; Hoffmann, T; Zhu, Y; Jahn, D

1998-10-01

114

Optimisation of optical properties of a long-wavelength GaInNAs quantum-well laser diode  

NASA Astrophysics Data System (ADS)

We report optimisation of optical properties of a strained GaInNAs/GaAs quantum-well laser, by taking into account the many-body effect theory and the bowing parameter. The theoretical transition energies and the GaInNAs bowing parameter are fitted into the photoluminescence spectrum of the GaInNAs quantum well, obtained in the experiment. The theoretical results for the photoluminescence spectrum and laser characteristics (light, current and voltage) exhibits a high degree of agreement with the experimental results.

Alias, M. S.; AL-Omari, A. N.; Maskuriy, F.; Faiz, F.; Mitani, S. M.

2013-11-01

115

Effect of Small Microfabrication Damage on Optical Characteristics of Laser Structure with GaInNAs Quantum Well  

NASA Astrophysics Data System (ADS)

We investigate the effect of micro-fabrication process damage on the photoluminescence characteristics of laser structures containing a GaInNAs and GaInAs quantum wells. By varying the size of the fabricated island structure, its impact on the photoluminescence intensity is studied. The GaInAs sample shows a strong decrease in its intensity with the reduction of the island size. In contrast, a slight increase is observed from the GaInNAs sample. This indicates the negligible impact of surface recombination on the GaInNAs sample, as well as the optical confinement within the micrometer-size island structure. The results suggest the feasibility of a GaInNAs gain medium for application to microfabricated optical devices.

Goto, Hiroaki; Ishikawa, Fumitaro; Morifuji, Masato; Kondow, Masahiko

2013-10-01

116

UAS Integration Into the NAS: An Examination of Baseline Compliance in the Current Airspace System  

NASA Technical Reports Server (NTRS)

As a result of the FAA Modernization and Reform Act of 2012, Unmanned Aerial Systems (UAS) are expected to be integrated into the National Airspace System (NAS) by 2015. Several human factors challenges need to be addressed before UAS can safely and routinely fly in the NAS with manned aircraft. Perhaps the most significant challenge is for the UAS to be non-disruptive to the air traffic management system. Another human factors challenge is how to provide UAS pilots with intuitive traffic information in order to support situation awareness (SA) of their airspace environment as well as a see-and-avoid capability comparable to manned aircraft so that a UAS pilot could safely maneuver the aircraft to maintain separation and collision avoidance if necessary. A simulation experiment was conducted to examine baseline compliance of UAS operations in the current airspace system. Researchers also examined the effects of introducing a Cockpit Situation Display (CSD) into a UAS Ground Control Station (GCS) on UAS pilot performance, workload and situation awareness while flying in a positively controlled sector. Pilots were tasked with conducting a highway patrol police mission with a Medium Altitude Long Endurance (MALE) UAS in L.A. Center airspace with two mission objectives: 1) to reroute the UAS when issued new instructions from their commander, and 2) to communicate with Air Traffic Control (ATC) to negotiate flight plan changes and respond to vectoring and altitude change instructions. Objective aircraft separation data, workload ratings, SA data, and subjective ratings regarding UAS operations in the NAS were collected. Results indicate that UAS pilots were able to comply appropriately with ATC instructions. In addition, the introduction of the CSD improved pilot SA and reduced workload associated with UAS and ATC interactions.

Fern, Lisa; Kenny, Caitlin A.; Shively, Robert J.; Johnson, Walter

2012-01-01

117

Improved container electrode coatings for Na/S battery systems. Final report  

SciTech Connect

Current sodium sulfur (Na/S) battery systems utilize the fast ion conducting properties of sodium beta{double_prime}-alumina electrolyte (BASE) to create high energy density sodium-sulfur electrochemical cells which can be used as components of secondary batteries. Since the days when these cells were invented at the Ford Motor Company Scientific Laboratory by J.T. Kummer and N. Weber, problems with container electrode corrosion have troubled the Na/S systems that have been developed in the many laboratories. In an unpublished investigation carried out at the Ford Motor Company laboratory, it was shown that titanium nitride films sputter deposited onto aluminum substrates under the appropriate conditions can exhibit excellent resistance to corrosion by sodium polysulfide melts. In the work carried out here, the corrosion resistant properties of TiN coatings sputter deposited on Al substrates have been investigated. TiN sputter coated aluminum samples were tested under static conditions in sodium sulfide melts and in Na/S cells under the range of electrochemical conditions needed for battery operation. The sputter deposited coatings produced in these experiments exhibited satisfactory corrosion resistance in the static tests but degraded under full cell operation. Tests of TiN coatings deposited by reactive ion-plating (IP), a common commercial process, showed excellent corrosion and electrical performance in both static and complete cell testing. Charge/discharge testing of sulfur core cells with IP coatings for over 350 cycles to 70 % depth of discharge has shown only very minor changes in cell performance and the tests are continuing.

Hunt, T.K. [Environmental Research Institute of Michigan, Ann Arbor, MI (United States). Applications Development Dept.

1995-08-01

118

Optimization of MOVPE-grown GaInNAs\\/GaAs quantum wells for 1.3-?m laser applications  

Microsoft Academic Search

The effects of high group-V precursor flows during metal-organic vapor phase epitaxial growth of GaInNAs QWs are investigated. It is shown that photoluminescence line width, wafer uniformity, and sensitivity to growth temperature can be improved using V\\/III ratios in excess of 2000. Broad area GaInNAs\\/GaAs SQW lasers with dimensions 100 × 820 ?m2 grown under these conditions have threshold current

C. Asplund; P. Sundgren; M. Hammar

2002-01-01

119

NAS (Numerical Aerodynamic Simulation Program) technical summaries, March 1989 - February 1990  

NASA Technical Reports Server (NTRS)

Given here are selected scientific results from the Numerical Aerodynamic Simulation (NAS) Program's third year of operation. During this year, the scientific community was given access to a Cray-2 and a Cray Y-MP supercomputer. Topics covered include flow field analysis of fighter wing configurations, large-scale ocean modeling, the Space Shuttle flow field, advanced computational fluid dynamics (CFD) codes for rotary-wing airloads and performance prediction, turbulence modeling of separated flows, airloads and acoustics of rotorcraft, vortex-induced nonlinearities on submarines, and standing oblique detonation waves.

1990-01-01

120

Production technology of beta-alumina ceramics for Na/S batteries  

NASA Astrophysics Data System (ADS)

Fabrication processes to produce tubes of beta-alumina ceramics for use in Na/S batteries were defined. The selection of raw materials, the handling of the beta-alumina powders, and development of a shaping technique were considered. Parameters for spray drying could not be clarified. Test results on firing in a tunnel kiln with high heating/cooling rates show that the beta-alumina tubes can be produced economically with sufficient density, microstructure, and chemical composition in a way that is transferable to real production. Nevertheless, there is the problem of reducing fuel consumption in the kiln.

Heimke, G.; Willmann, G.

1979-12-01

121

The OpenMP Implementation of NAS Parallel Benchmarks and its Performance  

NASA Technical Reports Server (NTRS)

As the new ccNUMA architecture became popular in recent years, parallel programming with compiler directives on these machines has evolved to accommodate new needs. In this study, we examine the effectiveness of OpenMP directives for parallelizing the NAS Parallel Benchmarks. Implementation details will be discussed and performance will be compared with the MPI implementation. We have demonstrated that OpenMP can achieve very good results for parallelization on a shared memory system, but effective use of memory and cache is very important.

Jin, Hao-Qiang; Frumkin, Michael; Yan, Jerry

1999-01-01

122

Two-Color Photoexcitation in a GaNAs/AlGaAs Quantum Well Solar Cell  

NASA Astrophysics Data System (ADS)

We demonstrate an efficient two-color photoexcitation process in a GaNAs/AlGaAs multiple quantum well (MQW) solar cell. The introduction of N into the GaAs MQW induces a marked reduction in bandgap energy, forming a large conduction band offset, and the formation of localized states. Owning to this deep confinement, the thermal escape of photogenerated carriers from the QWs is greatly suppressed even at room temperature, resulting in a reduction in photocurrent. An additional photocurrent is generated by a two-color absorption process of sub-bandgap photons.

Elborg, Martin; Jo, Masafumi; Ding, Yi; Noda, Takeshi; Mano, Takaaki; Sakoda, Kazuaki

2012-06-01

123

Growth and characterisation of Ga(NAsBi) alloy by metal-organic vapour phase epitaxy  

NASA Astrophysics Data System (ADS)

This paper summarises results of the epitaxial growth of Ga(NAsBi) by metal-organic vapour phase epitaxy (MOVPE) and the subsequent optical and structural characterisations of the samples. Ga(NAsBi)/GaAs multi-quantum well (MQW) samples are grown at 400 °C and single layers at 450 °C on GaAs (001) substrates. Triethylgallium (TEGa), tertiarybutylarsine (TBAs), trimethylbismuth (TMBi) and unsymmetrical dimethylhydrazine (UDMHy) are used as precursors. Secondary ion mass spectrometry (SIMS) shows that the Bi content is independent of the N content in the alloy. It is found that the N content depends on both UDMHy and TMBi supply during growth. High resolution X-ray diffraction (HR-XRD), scanning transmission electron microscopy (STEM) and atomic force microscopy (AFM) measurements show that samples with good crystalline quality can be realised. For samples containing 1.8% Bi and up to 1.8% N grown at 450 °C, photoreflectance spectroscopy (PR) shows a decrease in the band gap with increasing N content of 141±22 meV/% N.

Bushell, Z. L.; Ludewig, P.; Knaub, N.; Batool, Z.; Hild, K.; Stolz, W.; Sweeney, S. J.; Volz, K.

2014-06-01

124

Web Prep: How to Prepare NAS Reports For Publication on the Web  

NASA Technical Reports Server (NTRS)

This document contains specific advice and requirements for NASA Ames Code IN authors of NAS reports. Much of the information may be of interest to other authors writing for the Web. WebPrep has a graphic Table of Contents in the form of a WebToon, which simulates a discussion between a scientist and a Web publishing consultant. In the WebToon, Frequently Asked Questions about preparing reports for the Web are linked to relevant text in the body of this document. We also provide a text-only Table of Contents. The text for this document is divided into chapters: each chapter corresponds to one frame of the WebToons. The chapter topics are: converting text to HTML, converting 2D graphic images to gif, creating imagemaps and tables, converting movie and audio files to Web formats, supplying 3D interactive data, and (briefly) JAVA capabilities. The last chapter is specifically for NAS staff authors. The Glossary-Index lists web related words and links to topics covered in the main text.

Walatka, Pamela; Balakrishnan, Prithika; Clucas, Jean; McCabe, R. Kevin; Felchle, Gail; Brickell, Cristy

1996-01-01

125

Analysis of Depletion-Region Collection in GaInNAs Solar Cells  

SciTech Connect

We provide qualitative insight into depletion-region collection in GaInNAs cells to (1) understand the effect of diffusion length L on the QE; and (2) describe the magnitude of L required to get adequate current from the cell. We use Wolf's equations for the QE including a drift field E, and model E as being equal to the junction built-in voltage distributed uniformly across the depletion region. This allows us to calculate the QE as a function of L and depletion width WD. We show that if L is sufficiently small, increasing WD can actually decrease the QE. To determine how long L needs to be in a practical GaInNAs junction, we calculate from the QE the short-circuit current density as a function of WD and L. This allows us to estimate that Lambipolar needs to be greater than roughly 1 {micro}m in order to obtain enough photocurrent for the 4-junction application, giving guidance to the experimental effort to develop such cells.

Friedman, D. J.; Ptak, A. J.; Kurtz, S. R.; Geisz, J. F.

2005-02-01

126

CLEARANCE OF BULK MATERIALS FROM D&D - LIFE AFTER THE NAS REPORT  

SciTech Connect

Lack of consistent free release standards for solid materials has been an issue that has been around for several decades. The Nuclear Regulatory Commission (NRC) has had specific and dose-based standards for the release of liquids and gases for several decades, but no regulatory mechanisms for the release of solid materials from a nuclear power plant. Even though free releases of small quantities of solid materials continue under existing guidelines from operating plants, the regulatory void creates major difficulties for the bulk materials that result from decommissioning projects. For the nation's fleet of nuclear reactors the cost of this regulatory void could be as high as $10 billion. The NRC has recently resumed the enhanced rulemaking process that was originally initiated in 1999 but was deferred pending a study by the National Academy of Sciences (NAS)/National Research Council. The NAS report and recommendations were issued in March 2002 and the NRC decided in October 2002 to resume the rulemaking process. This paper provides an overview of the developments in this area. It specifically discusses the applicability of ANSI N13.12 as a consensus standard that should be seriously considered for adoption as a regulatory standard.

Devgun, Jas S., Ph.D.

2003-02-27

127

Minority carrier transport properties of GaInNAs heterojunction bipolar transistors with 2% nitrogen  

NASA Astrophysics Data System (ADS)

GaAs-based heterojunction bipolar transistors (HBTs) have a relatively large turn-on voltage of approximately 1.4 V that can only be decreased by reducing the band-gap energy of the base material. For a variety of applications, particularly operation with low power supply voltage and reduced power dissipation, it would be desirable to have a smaller value of turn-on voltage. We report the performance of NpN double heterojunction bipolar transistors fabricated on a GaAs substrate with a Ga0.89In0.11N0.02As0.98 base that has a band-gap energy (Eg) of 0.98 eV; this is achieved with a nitrogen composition of 2%. These devices have a turn-on voltage VBE that is 0.4 V lower than that of their GaAs-base counterparts. The peak incremental current gain HFE is 8. The current gain of nitrogen containing HBTs is degraded due to the complex change in transport properties of carriers through the GaInNAs base region. In this article, the transport properties of GaInNAs-base HBTs are investigated by temperature-dependent dc current-voltage characteristics, optical and high frequency small-signal electrical measurements. The characterization of these devices is important to understand the effect of nitrogen on the device performance.

Welty, Rebecca J.; Xin, Huoping; Tu, Charles W.; Asbeck, Peter M.

2004-01-01

128

Growth optimization and optical properties of AlGaNAs alloys  

NASA Astrophysics Data System (ADS)

The effect of Al on the surface morphology of chemical beam epitaxy grown AlGaNAs alloys is studied. Pits attributed to N clustering appearing on the dilute nitride surface become smaller, denser, and more uniformly distributed in the presence of Al. This reveals that the introduction of Al results in more homogenous N atoms spatial distribution. A growth temperature study reveals the formation of 3D structures at high temperature due to phase separation. The density of these structures decreases, while their diameter and height increase when the temperature is raised from 380 °C to 565 °C. At growth temperatures in the 380-420 °C range, the phase separation is suppressed and the growth mode is 2D. At 420 °C, the N incorporation is also maximized, making it the optimum temperature. The absorption coefficient and the bandgap of AlGaNAs alloys are extracted from transmittance measurement. A good agreement is obtained between the experimentally measured bandgap and the theoretical values calculated using the band anticrossing model. A bandgap as low as 1.22 eV was reached using Al and N concentrations of ˜15% and ˜3.4%, respectively.

Kolhatkar, Gitanjali; Boucherif, Abderraouf; Valdivia, Christopher E.; Wallace, Steven G.; Fafard, Simon; Aimez, Vincent; Arès, Richard

2014-04-01

129

NAS Demand Predictions, Transportation Systems Analysis Model (TSAM) Compared with Other Forecasts  

NASA Technical Reports Server (NTRS)

The current work incorporates the Transportation Systems Analysis Model (TSAM) to predict the future demand for airline travel. TSAM is a multi-mode, national model that predicts the demand for all long distance travel at a county level based upon population and demographics. The model conducts a mode choice analysis to compute the demand for commercial airline travel based upon the traveler s purpose of the trip, value of time, cost and time of the trip,. The county demand for airline travel is then aggregated (or distributed) to the airport level, and the enplanement demand at commercial airports is modeled. With the growth in flight demand, and utilizing current airline flight schedules, the Fratar algorithm is used to develop future flight schedules in the NAS. The projected flights can then be flown through air transportation simulators to quantify the ability of the NAS to meet future demand. A major strength of the TSAM analysis is that scenario planning can be conducted to quantify capacity requirements at individual airports, based upon different future scenarios. Different demographic scenarios can be analyzed to model the demand sensitivity to them. Also, it is fairly well know, but not well modeled at the airport level, that the demand for travel is highly dependent on the cost of travel, or the fare yield of the airline industry. The FAA projects the fare yield (in constant year dollars) to keep decreasing into the future. The magnitude and/or direction of these projections can be suspect in light of the general lack of airline profits and the large rises in airline fuel cost. Also, changes in travel time and convenience have an influence on the demand for air travel, especially for business travel. Future planners cannot easily conduct sensitivity studies of future demand with the FAA TAF data, nor with the Boeing or Airbus projections. In TSAM many factors can be parameterized and various demand sensitivities can be predicted for future travel. These resulting demand scenarios can be incorporated into future flight schedules, therefore providing a quantifiable demand for flights in the NAS for a range of futures. In addition, new future airline business scenarios are investigated that illustrate when direct flights can replace connecting flights and larger aircraft can be substituted, only when justified by demand.

Viken, Jeff; Dollyhigh, Samuel; Smith, Jeremy; Trani, Antonio; Baik, Hojong; Hinze, Nicholas; Ashiabor, Senanu

2006-01-01

130

Comparison of 250 MHz R10K Origin 2000 and 400 MHz Origin 2000 Using NAS Parallel Benchmarks  

NASA Technical Reports Server (NTRS)

This report describes results of benchmark tests on Steger, a 250 MHz Origin 2000 system with R10K processors, currently installed at the NASA Ames National Advanced Supercomputing (NAS) facility. For comparison purposes, the tests were also run on Lomax, a 400 MHz Origin 2000 with R12K processors. The BT, LU, and SP application benchmarks in the NAS Parallel Benchmark Suite and the kernel benchmark FT were chosen to measure system performance. Having been written to measure performance on Computational Fluid Dynamics applications, these benchmarks are assumed appropriate to represent the NAS workload. Since the NAS runs both message passing (MPI) and shared-memory, compiler directive type codes, both MPI and OpenMP versions of the benchmarks were used. The MPI versions used were the latest official release of the NAS Parallel Benchmarks, version 2.3. The OpenMP versions used were PBN3b2, a beta version that is in the process of being released. NPB 2.3 and PBN3b2 are technically different benchmarks, and NPB results are not directly comparable to PBN results.

Turney, Raymond D.; Thigpen, William W. (Technical Monitor)

2001-01-01

131

Parallelization of the NAS Conjugate Gradient Benchmark Using the Global Arrays Shared Memory Programming Model  

SciTech Connect

The NAS Conjugate Gradient (CG) benchmark is an important scientific kernel used to evaluate machine performance and compare characteristics of different programming models. Global Arrays (GA) toolkit supports a shared memory programming paradigm— even on distributed memory systems— and offers the programmer control over the distribution and locality that are important for optimizing performance on scalable architectures. In this paper, we describe and compare two different parallelization strategies of the CG benchmark using GA and report performance results on a shared-memory system as well as on a cluster. Performance benefits of using shared memory for irregular/sparse computations have been demonstrated before in context of the CG benchmark using OpenMP. Similarly, the GA implementation outperforms the standard MPI implementation on shared memory system, in our case the SGI Altix. However, with GA these benefits are extended to distributed memory systems and demonstrated on a Linux cluster with Myrinet.

Zhang, Yeliang; Tipparaju, Vinod; Nieplocha, Jarek; Hariri, Salim

2005-04-08

132

Development of computer program NAS3D using Vector processing for geometric nonlinear analysis of structures  

NASA Technical Reports Server (NTRS)

An algorithm for vectorized computation of stiffness matrices of an 8 noded isoparametric hexahedron element for geometric nonlinear analysis was developed. This was used in conjunction with the earlier 2-D program GAMNAS to develop the new program NAS3D for geometric nonlinear analysis. A conventional, modified Newton-Raphson process is used for the nonlinear analysis. New schemes for the computation of stiffness and strain energy release rates is presented. The organization the program is explained and some results on four sample problems are given. The study of CPU times showed that savings by a factor of 11 to 13 were achieved when vectorized computation was used for the stiffness instead of the conventional scalar one. Finally, the scheme of inputting data is explained.

Mangalgiri, P. D.; Prabhakaran, R.

1986-01-01

133

Security Risk Assessment Process for UAS in the NAS CNPC Architecture  

NASA Technical Reports Server (NTRS)

This informational paper discusses the risk assessment process conducted to analyze Control and Non-Payload Communications (CNPC) architectures for integrating civil Unmanned Aircraft Systems (UAS) into the National Airspace System (NAS). The assessment employs the National Institute of Standards and Technology (NIST) Risk Management framework to identify threats, vulnerabilities, and risks to these architectures and recommends corresponding mitigating security controls. This process builds upon earlier work performed by RTCA Special Committee (SC) 203 and the Federal Aviation Administration (FAA) to roadmap the risk assessment methodology and to identify categories of information security risks that pose a significant impact to aeronautical communications systems. A description of the deviations from the typical process is described in regards to this aeronautical communications system. Due to the sensitive nature of the information, data resulting from the risk assessment pertaining to threats, vulnerabilities, and risks is beyond the scope of this paper

Iannicca, Dennis Christopher; Young, Daniel Paul; Suresh, Thadhani; Winter, Gilbert A.

2013-01-01

134

Morphological changes in the sulfur electrode of lifecycle-tested Na/S cells  

SciTech Connect

Morphological studies of the sulfur electrode have provided important insights into the factors that influence the performance of Na/S cells. The observed compositional gradients indicate that multiple reaction fronts arise within the electrode during cycling through the two-liquid compositional range. Present models predicting this behavior inadequately describe the location of these fronts. The pattern of changes in Na and S distribution is repeated with each charge-discharge cycle; however, the morphology is progressively altered by corrosion products, especially the migratory compounds of NaAlS/sub 2/ and NaCrS/sub 2/. As a result of a cycle-dependent transport mechanism, the latter compound becomes concentrated in the electrode adjacent to the electrolyte. Cells that fail because of electrolyte fractures form solid sodium polysulfides within the sulfur electrode. On occasion, the uncontrolled growth of solid phases undermines the integrity of the container.

Smaga, J.A.

1986-01-01

135

Photolytic Destruction Technology demonstration, NAS North Island, Site 9. Final contract report, October 1997--February 1998  

SciTech Connect

The Photolytic Destruction Technology was chosen for demonstration, as part of the Navy Environmental Leadership Program (NELP), at Naval Air Station (NAS) North Island`s Site 9 soil vapor extraction (SVE) system. The demonstration was conducted, under contract N47408-97-C-0215 through Naval Facilities Engineering Service Center`s Broad Agency Announcement (BAA) program, to Process Technologies Incorporated (PTI), beginning October 7, 1997 and ending February 12, 1998, for 128 days. The literature search, demonstration oversight, and evaluation were funded by the Pollution Abatement Ashore Program managed by Naval Facilities Engineering Command and sponsored by the Environmental Protection, Safety and Occupational Health Division (N45) of the Chief of Naval Operations. The system was installed to treat a slip stream containing volatile organic compounds (VOCs) from the operating SVE system already installed at the site. The goal of this demonstration was to obtain the necessary cost and performance data, including the lessons learned, on the system comprising of a concentrator, condenser, and photolytic destruction unit (PDU), for comparison with other treatment technologies. The system was demonstrated on air stream contaminated with halogenated and non-halogenated VOCs such as l,2- dichloroethene, trichloroethene, tetrachloroethene, toluene, and octane. The test results indicated that the system was effective in removing VOCs in thc SVE off-gas to below the maximum allowable emissions of 25 parts per million by volume. The average total DRE achieved for VOCs was 95.44% whereas the PDU alone demonstrated an overall DRE of 97%. The estimated unit cost to treat SVE off-gas at NAS North Island`s Site 9, for a 3,000 standard cubic feet per minute PTI system, is $3.77 per pound of VOC treated.

NONE

1998-08-01

136

Mid-infrared luminescence of an InNAsSb/InAs single quantum well grown by molecular beam epitaxy  

SciTech Connect

The authors report the growth and characterization of a dilute nitride, InNAsSb/InAs, by solid source molecular beam epitaxy. Optimizing growth conditions for nitrogen incorporation has resulted in high-quality InNAsSb epilayers without any structural degradation, as confirmed by high-resolution x-ray diffraction. Optical properties were investigated by temperature dependent and excitation power dependent photoluminescence. The authors obtained mid-infrared luminescence around 4 {mu}m at low temperature, which reveals strong carrier localization behavior at low temperature, induced by nitrogen and antimony interaction. The band alignment of InNAsSb/InAs can be type I instead of the conventional type II found for InAsSb/InAs. A conduction band offset, E{sub c}, of {approx}102 meV was obtained.

Yuen, Homan B.; Kim, Seongsin M.; Hatami, Fariba; Harris, James S.; Chin, Alan H. [Solid State and Photonics Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California 94305-4075 (United States); Center for Nanotechnology, NASA Ames Research Center, Moffett Field, California 94035 (United States)

2006-09-18

137

Theoretical studies of optical gain tuning by hydrostatic pressure in GaInNAs/GaAs quantum wells  

NASA Astrophysics Data System (ADS)

In order to describe theoretically the tuning of the optical gain by hydrostatic pressure in GaInNAs/GaAs quantum wells (QWs), the optical gain calculations within kp approach were developed and applied for N-containing and N-free QWs. The electronic band structure and the optical gain for GaInNAs/GaAs QW were calculated within the 10-band kp model which takes into account the interaction of electron levels in the QW with the nitrogen resonant level in GaInNAs. It has been shown that this interaction increases with the hydrostatic pressure and as a result the optical gain for GaInNAs/GaAs QW decreases by about 40% and 80% for transverse electric and transverse magnetic modes, respectively, for the hydrostatic pressure change from 0 to 40 kilobars. Such an effect is not observed for N-free QWs where the dispersion of electron and hole energies remains unchanged with the hydrostatic pressure. This is due to the fact that the conduction and valence band potentials in GaInAs/GaAs QW scale linearly with the hydrostatic pressure.

Gladysiewicz, M.; Kudrawiec, R.; Wartak, M. S.

2014-01-01

138

Modeling of optical gain in GaInNAs quantum wells by using 8-band and 10-band models  

NASA Astrophysics Data System (ADS)

We analyzed two approaches to calculate band structure and optical gain in GaInNAs/GaAs quantum well structures based on 10-band and 8-band kp models. The obtained results are discussed in the context of importance of conduction band nonparabolicity. We also briefly report on the influence of hydrostatic pressure on optical gain in this system.

Gladysiewicz, M.; Wartak, M. S.

2014-03-01

139

Right and Wrong and Cultural Diversity: Replication of the 2002 NAS/Zogby Poll on Business Ethics  

ERIC Educational Resources Information Center

In April 2002, a NAS/Zogby poll found that only a quarter of sampled students perceived uniform standards of "right and wrong" and that most students felt that ethical behavior depends on cultural diversity. In this effort to replicate those findings in a larger sample of American college students, the authors obtained results that contradict the…

Ludlum, Marty; Mascaloinov, Sergei

2004-01-01

140

National Academy of Sciences (NAS) Study entitled The Effect of Climate Change on Indoor Air Quality and Public Health.  

EPA Science Inventory

The Institute of Medicine of the NAS is conducting a study to evaluate the state of scientific understanding of the effects of climate change on indoor air quality and public health. General topics may include the likely impacts of climate change in the U.S. on the indoor environ...

141

Improvement of Sealing Performance for Nas Battery by a Surface Modification Process  

NASA Astrophysics Data System (ADS)

A gradient film of Na-beta-Al2O3 has been fabricated by a gas-solid reaction method to improve the sealing performance for the Na/S battery. The effect of the substrate surface pre-treatment methods on the thickness of the gradient films and the thermophysical characteristics of the gradient films have been systematically studied. It shows that the pre-treatment method on the surface of the alpha-Al2O3 has a great influence on the thickness of the film. The substrate pre-treated by MgCO3 could react with alpha-Al2O3, accompanied by the generation of spinel MgAl2O4, which could promote the formation of the Na-beta-Al2O3 film, resulting in the thickness of the Na-beta-Al2O3 film as thick as 100?m. The thermal shock resistance and thermal stability of the films were also satisfactory. The constituent of the gradient film was unchanged after thermal shock for 100 times. No micro-crack was observed on the film after heating the sample at 350 °C for 100h. The interfaces between the glass and substrates have also been analyzed.

Zhang, Gaoxiao; Wen, Zhaoyin; Wu, Xiangwei; Ma, Guoqiang

2013-07-01

142

Evidence of an oxygen recombination center in p+-n GaInNAs solar cells  

NASA Astrophysics Data System (ADS)

We have studied deep-level impurities in p+-n GaInNAs solar cells using deep-level transient spectroscopy (DLTS). These films were grown by atmospheric- and low-pressure metalorganic vapor-phase epitaxy. The base layer is doped with silicon, and the emitter layer is zinc doped. Two types of samples have been studied: samples were grown with and without the addition of oxygen impurity. Two electron traps were found in all samples. These are designated as: E1, at EC-0.23-EC-0.27 eV, E2 at EC-0.45 eV, and E2* at 0.77 eV. With the addition of oxygen impurity, DLTS showed additional traps designated as E3 (electron) at EC-0.59 eV and H3 (hole) at EV+0.59 eV. Using secondary ion mass spectroscopy, the oxygen concentration was found to be about 2-3×1019 and 1×1017 cm-3 in two sets of samples. However, only samples containing oxygen contained the two near-midgap levels (E3 and H3). We present evidence that these levels are associated with the oxygen defect. As we change the dc bias voltage, the E3 trap disappears in unison with the appearance of the H3 trap. Furthermore, E3 and H3 trap levels have comparable capture cross sections. This oxygen-related trap is an effective recombination center. The measured Shockley-Hall-Read lifetime for this center is about 0.6 ?s.

Balcioglu, A.; Ahrenkiel, R. K.; Friedman, D. J.

2000-04-01

143

Fluidized Bed Steam Reformer (FBSR) Na-AI-SI (NAS) Waste Form for Hanford LAW and Secondary Waste  

SciTech Connect

FBSR sodium-aluminosilicate (NAS) waste form has been identified as a promising supplemental treatment technology for Hanford LAW and/or Waste Treatment Plant Secondary Waste (WTP-SW). Objectives of the project: 1) Prove the robustness of FBSR as a waste form for either LAW and/or WTP-SW; 2) Reduce the risk associated with implementing the FBSR NAS waste form as a supplemental treatment technology for Hanford LAW and/or WTP-SW; 3) Conduct two treatability studies with SRS radioactive wastes that have been shimmed to look like Hanford WTP-SW and LAW; 4) Conduct three treatability studies with actual Hanford tank wastes; 5) Fill key data gaps; 6) Link previous and new results together.

Jantzen, C.; Pierce, E.

2010-11-01

144

Improvements in GaInNAs\\/GaAs quantum-well lasers using focused ion beam post-processing  

Microsoft Academic Search

At the present time, there is a considerable demand for long wavelength (1.3mum-1.5mum) laser diodes for low cost data-communication applications capable of operating at high speed and at high ambient temperatures without the need for thermoelectric coolers. First proposed in 1995 by M. Kondow, the GaInNAs\\/GaAs material system has attracted a great deal of interest as it promises good temperature

J. Pozo; J. Hu; J. M. Rorison; M. Saarinen; J. Konttinen; J. Viheriälä; P. Leinonen; T. Jouhti; M. Pessa

2006-01-01

145

Constitutive Overexpression of the OsNAS Gene Family Reveals Single-Gene Strategies for Effective Iron- and Zinc-Biofortification of Rice Endosperm  

PubMed Central

Background Rice is the primary source of food for billions of people in developing countries, yet the commonly consumed polished grain contains insufficient levels of the key micronutrients iron (Fe), zinc (Zn) and Vitamin A to meet daily dietary requirements. Experts estimate that a rice-based diet should contain 14.5 µg g?1 Fe in endosperm, the main constituent of polished grain, but breeding programs have failed to achieve even half of that value. Transgenic efforts to increase the Fe concentration of rice endosperm include expression of ferritin genes, nicotianamine synthase genes (NAS) or ferritin in conjunction with NAS genes, with results ranging from two-fold increases via single-gene approaches to six-fold increases via multi-gene approaches, yet no approach has reported 14.5 µg g?1 Fe in endosperm. Methodology/Principal Findings Three populations of rice were generated to constitutively overexpress OsNAS1, OsNAS2 or OsNAS3, respectively. Nicotianamine, Fe and Zn concentrations were significantly increased in unpolished grain of all three of the overexpression populations, relative to controls, with the highest concentrations in the OsNAS2 and OsNAS3 overexpression populations. Selected lines from each population had at least 10 µg g?1 Fe in polished grain and two OsNAS2 overexpression lines had 14 and 19 µg g?1 Fe in polished grain, representing up to four-fold increases in Fe concentration. Two-fold increases of Zn concentration were also observed in the OsNAS2 population. Synchrotron X-ray fluorescence spectroscopy demonstrated that OsNAS2 overexpression leads to significant enrichment of Fe and Zn in phosphorus-free regions of rice endosperm. Conclusions The OsNAS genes, particularly OsNAS2, show enormous potential for Fe and Zn biofortification of rice endosperm. The results demonstrate that rice cultivars overexpressing single rice OsNAS genes could provide a sustainable and genetically simple solution to Fe and Zn deficiency disorders affecting billions of people throughout the world.

Johnson, Alexander A. T.; Kyriacou, Bianca; Callahan, Damien L.; Carruthers, Lorraine; Stangoulis, James; Lombi, Enzo; Tester, Mark

2011-01-01

146

Functional and structural characterization of the zebrafish Na+-sulfate cotransporter 1 (NaS1) cDNA and gene (slc13a1).  

PubMed

Sulfate plays an essential role during growth, development and cellular metabolism. In this study, we characterized the function and structure of the zebrafish (Danio rerio) Na+-sulfate cotransporter 1 (NaS1) cDNA and gene (slc13a1). Zebrafish NaS1 encodes a protein of 583 amino acids with 13 putative transmembrane domains. Expression of zebrafish NaS1 protein in Xenopus oocytes led to Na+-sulfate cotransport, which was significantly inhibited by thiosulfate, selenate, molybdate, and tungstate. Zebrafish NaS1 transport kinetics were: V(max) = 1,731.670 +/- 92.853 pmol sulfate/oocyte.hour and K(m) = 1.414 +/- 0.275 mM for sulfate and V(max) = 307.016 +/- 32.992 pmol sulfate/oocyte x hour, K(m) = 24.582 +/- 4.547 mM and n (Hill coefficient) = 1.624 +/- 0.354 for sodium. Zebrafish NaS1 mRNA is developmentally expressed in embryos from day 1 postfertilization and in the intestine, kidney, brain, and eye of adult zebrafish. The zebrafish NaS1 gene slc13a1 contains 15 exons spanning 8,716 bp. Characterization of the zebrafish NaS1 contributes to a greater understanding of sulfate transporters in a well-defined genetic model and will allow the elucidation of evolutionary and functional relationships among vertebrate sulfate transporters. PMID:18544660

Markovich, Daniel; Romano, Alessandro; Storelli, Carlo; Verri, Tiziano

2008-08-15

147

High responsivity GaNAsSb p-i-n photodetectors at 1.3 microm grown by radio-frequency nitrogen plasma-assisted molecular beam epitaxy.  

PubMed

GaNAsSb/GaAs p-i-n photo notdetectors with an intrinsic GaNAsSb photoabsorption layer grown at 350 degrees C, 400 degrees C, 440 degrees C and 480 degrees C, have been prepared using radio-frequency nitrogen plasma-assisted molecular beam epitaxy in conjunction with a valved antimony cracker source. The i-GaNAsSb photoabsorption layer contains 3.3% of nitrogen and 8% of antimony, resulting in DC photo-response up to wavelengths of 1350 nm. The device with i-GaNAsSb layer grown at 350 degrees C exhibits extremely high photoresponsivity of 12A/W at 1.3 microm. These photodetectors show characteristics which strongly suggest the presence of carrier avalanche process at reverse bias less than 5V. PMID:18545482

Tan, K H; Yoon, S F; Loke, W K; Wicaksono, S; Ng, T K; Lew, K L; Stöhr, A; Fedderwitz, S; Weiss, M; Jäger, D; Saadsaoud, N; Dogheche, E; Decoster, D; Chazelas, J

2008-05-26

148

Draft Environmental Impact Statement, Realignment of F/A-18 Aircraft and Operational Functions from Naval Air Station (NAS) Cecil Field, Florida, to Other East Coast Installations.  

National Technical Information Service (NTIS)

This Draft Environmental Impact Statement (DEIS) addresses the environmental issues associated with the realignment of F/A-18 aircraft (i.e., fleet squadrons and the Fleet Replacement Squadron FRS) and operational functions from Naval Air Station (NAS) Ce...

1997-01-01

149

High-speed picosecond pulse response GaNAsSb p-i-n photodetectors grown by rf plasma-assisted nitrogen molecular beam epitaxy  

Microsoft Academic Search

The authors report on picosecond pulse response GaNAsSb\\/GaAs p-i-n photodetectors grown by molecular beam epitaxy in conjunction with a rf plasma-assisted nitrogen source. The 2 mum thick GaNAsSb photoabsorption layer contains 3.3% of N and 8% of Sb resulting in a dc photoresponse up to 1380 nm wavelength. Dark current densities at 0 and -5 V are 1.6×10-5 and 13

K. H. Tan; S. F. Yoon; W. K. Loke; S. Wicaksono; K. L. Lew; A. Stöhr; O. Ecin; A. Poloczek; A. Malcoci; D. Jäger

2007-01-01

150

Remotely Operated Aircraft (ROA) Impact on the National Airspace System (NAS) Work Package: Data Modeling and Sharing Perspective for Development of a Common Operating Picture  

NASA Technical Reports Server (NTRS)

This report documents analyses that were performed in support of Task #3 of Work Package #3 (WP3), ROA Impact on the NAS. The purpose of the overall work package was to determine if there are any serious issues that would prevent or prohibit ROA's flying in the NAS on a routine basis, and if so, what actions should be taken to address them. The purpose of Task #3 was to look at this problem from the perspective of data modeling and sharing.

2007-01-01

151

Effects of thermal annealing procedure and a strained intermediate layer on a highly-strained GaInNAs\\/GaAs double-quantum-well structure  

Microsoft Academic Search

We investigated the effects of a thermal annealing procedure and a strained intermediate layer on a highly-strained GaInNAs\\/GaAs double-quantum-well (DQW) structure grown by chemical beam epitaxy (CBE). To improve the crystal quality of the DQW structure, we have developed a layer-by-layer annealing procedure, in which thermal annealing is done just after the crystal growth of each GaInNAs well layer. This

T. Kitatani; M Kondow; T Tanaka

2000-01-01

152

Molecular beam epitaxy growth of 1.55 ? m GaInNAs(Sb) double quantum wells with bright and narrow photoluminescence  

Microsoft Academic Search

GaInNAs(Sb)\\/GaNAs double quantum well (DQW) structures were grown on GaAs substrates using solid-source molecular beam epitaxy with N2\\/Ar gas mixtures in a radio frequency plasma cell. A novel method of in situ antimony mass spectrometry is introduced which permits flux monitoring in the presence of large arsenic background pressures. For a DQW sample grown without Sb, bright and narrow (38.1meV)

J. A. Gupta; G. I. Sproule; X. Wu; Z. R. Wasilewski

2006-01-01

153

Theoretical Studies of the Influence of Temperature on Photoluminescence Dynamics in GaInNAs/GaAs Quantum Wells  

NASA Astrophysics Data System (ADS)

Dynamics of excitons in GaInNAs/GaAs quantum wells (QWs) is studied theoretically within a model of hopping excitons. In this model the temporal evolution of photoluminescence (PL) is described by the system of rate equations which takes into account hopping of excitons between randomly generated localizing states. In this work we study the influence of temperature on such characteristic features of PL as the decay and rise time of PL signal as well as their spectral dependences. It is clearly shown that our model reproduces experimental data very well.

Baranowski, Micha?; Kudrawiec, Robert; Misiewicz, Jan

2013-08-01

154

The CSM testbed software system: A development environment for structural analysis methods on the NAS CRAY-2  

NASA Technical Reports Server (NTRS)

The Computational Structural Mechanics (CSM) Activity at Langley Research Center is developing methods for structural analysis on modern computers. To facilitate that research effort, an applications development environment has been constructed to insulate the researcher from the many computer operating systems of a widely distributed computer network. The CSM Testbed development system was ported to the Numerical Aerodynamic Simulator (NAS) Cray-2, at the Ames Research Center, to provide a high end computational capability. This paper describes the implementation experiences, the resulting capability, and the future directions for the Testbed on supercomputers.

Gillian, Ronnie E.; Lotts, Christine G.

1988-01-01

155

Electron-irradiation enhanced photoluminescence from GaInNAs/GaAs quantum wells subject to thermal annealing  

SciTech Connect

Electron irradiation of a 1.3-{mu}m-GaInNAs/GaAs multi-quantum-well heterostructure, grown by molecular beam epitaxy and subsequently rapid-thermal annealed, is found to induce much stronger photoluminescence than what is observed for an identical as-grown sample upon annealing. Annealing of the irradiated sample also causes a small additional spectral blueshift and reduces alloy potential energy fluctuations at the conduction band minimum. These irradiation-related phenomena are accompanied by small but discernable changes in x-ray diffraction features upon annealing, which indicate compositional and/or structural changes in the quantum wells.

Pavelescu, E.-M.; Gheorghiu, A.; Dumitrescu, M.; Tukiainen, A.; Jouhti, T.; Hakkarainen, T.; Kudrawiec, R.; Andrzejewski, J.; Misiewicz, J.; Tkachenko, N.; Dhaka, V.D.S.; Lemmetyinen, H.; Pessa, M. [Optoelectronics Research Centre, P.O. Box 692, and Institute of Materials Chemistry, P.O. Box 541, Tampere University of Technology, 33101 Tampere (Finland); Hyperion University, Calea Calarasi 169, 74118 Bucharest (Romania); Optoelectronics Research Centre, Tampere University of Technology, P.O. Box 692, 33101 Tampere (Finland); Institute of Physics, Wroclaw University of Technology Wybrzeze Wyspianskiego 27, 50-370 Wroclaw (Poland); Institute of Materials Chemistry, Tampere University of Technology, P.O. Box 541, 33101 Tampere (Finland); Optoelectronics Research Centre, Tampere University of Technology, P.O. Box 692, 33101 Tampere (Finland)

2004-12-20

156

Enhanced luminescence in GaInNAsSb quantum wells through variation of the arsenic and antimony fluxes  

SciTech Connect

Photoluminescence efficiency was enhanced in molecular-beam-epitaxial-grown 1.55-{mu}m GaInNAsSb single quantum wells through modulation of the arsenic and antimony fluxes. The arsenic-to-antimony flux ratio was found to be a key consideration at reduced group-V fluxes in maintaining the beneficial effects of antimony while reducing the number of point defects, most likely arsenic antisites. Samples were also characterized by high-resolution x-ray diffraction, secondary ion mass spectrometry, and low-temperature photoluminescence. These findings offer a means to substantially reduce dilute-nitride laser threshold current densities.

Bank, Seth R.; Yuen, Homan B.; Bae, Hopil; Wistey, Mark A.; Moto, Akihiro; Harris, James S. [Solid State and Photonics Laboratory, Stanford University, Stanford, California 94305 (United States); Innovation Core SEI, Inc., Santa Clara, California 95051 (United States); Solid State and Photonics Laboratory, Stanford University, Stanford, California 94305 (United States)

2006-06-12

157

Investigations of (GaIn)(NAs) bulk layers and (GaIn)(NAs)/GaAs multiple quantum well structures grown using tertiarybutylarsine (TBAs) and 1,1-dimethylhydrazine (UDMHy)  

NASA Astrophysics Data System (ADS)

The optimization of the metalorganic vapour phase epitaxial (MOVPE) growth of lattice-matched (GaIn)(NAs)/GaAs multiple quantum well (MQW) structures grown by using triethylgallium (TEGa) and trimethylindium (TMIn) in combination with tertiarybutyl arsine (TBAs) and 1,1-dimethylhydrazine (UDMHy) is investigated in detail by means of high resolution X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) as well as photoluminescence (PL) measurements. The temperature range for the realization of high structural layer quality is established from about 500 to 525°C. MQWH with extremely narrow XRD linewidths of 21? (FWHM) are achieved. The N-incorporation behaviour as a function of TBAs partial pressure, As/N-partial pressure ratio and of the growth rate is clarified in detail. The N-incorporation is reduced with increasing In-content in the (GaIn)(NAs) layer. Excellent surface morphologies indicatetd by smooth terraces with monolayer height steps are achieved for N-concentrations up to 4.5%. Above this critical value a deterioriation in structural quality is observed. The band gap reduction with increasing N-incorporation is established from PL studies at room temperature. The optical characteristics as a function of N-concentration and growth conditions are discussed briefly. PL emission of as-grown samples with wavelengths up to 1.55 ?m at room temperature is achieved.

Höhnsdorf, F.; Koch, J.; Agert, C.; Stolz, W.

1998-12-01

158

Experiencias com Processamento Digital de Imagens no INPE (Instituto de Pesquisas Espaciais) (Experiences with Digital Processing of Images at INPE (Instituto de Pesquisas Espaciais)).  

National Technical Information Service (NTIS)

Four different research experiments with digital image processing at INPE will be described: (1) edge detection by hypothesis testing; (2) image interpolation by finite impulse response filters; (3) spatial feature extraction methods in multispectral clas...

N. D. A. Mascarenhas

1984-01-01

159

MBE growth of InAs self-assembled quantum dots embedded in GaNAs strain-compensating layers  

NASA Astrophysics Data System (ADS)

We fabricated self-assembled InAs quantum dots (QDs) embedded with a combined set of a GaNAs strain-compensating layer (SCL) and an InGaAs strain-reducing layer (SRL) by using atomic hydrogen-assisted molecular beam epitaxy (H-MBE) with a RF plasma nitrogen source. By inserting an InGaAs SRL between the InAs QD layer and GaNAs SCL, we were able to achieve a significant improvement of optical properties. A 1.3 ?m-range photoluminescence (PL) emission was clearly obtained at 300 K from QDs embedded in a 5 nm-thick In 0.15Ga 0.85As SRL followed by a 20 nm-thick GaN 0.008As 0.992 SCL. Further, PL emission from the first excited state of QDs was also observed under a high excitation intensity of ˜20.0 W/cm2.

Hashimoto, Takayuki; Oshima, Ryuji; Shigekawa, Hidemi; Okada, Yoshitaka

2007-04-01

160

Basic study for the construction of solar cell using CdS photocatalysts and NaS electrolyte  

NASA Astrophysics Data System (ADS)

Photoexcited electrons pathway from thin film consisting of semiconductor particles to electrode was tried to develop by using conducting polymers. PEDOT/PSS and polyaniline was selected as transparent conducting polymer material. In the case of the cell consisted by using polyaniline, it was confirmed that conductive emeraldine salt stated polyaniline converted to non-conductive emeraldine base state because of contact with strong basic NaS electrolyte solution. On the other hand, as regards the cell with PEDOT/PSS, it was expected that positive and negative electrode short-circuited and/or Schottky junction was formed between CdS and PEDOT/PSS. The formation of Schottky junction between CdS and PEDOT/PSS was reduced the kinetic energy of the photoexcited electrons to 5.1eV which was the Fermi level of PEDOT. These electrons could not reduce NaS electrolyte solution since oxidation-reduction potential was 4.1eV. As a result, it considered that photoexcited electrons transfer was restricted, which read the decreasement of mobility of photoexcited electron, while the cell "without" PEDOT/PSS could operate as a solar cell.

Mabuchi, Takashi; Hayashi, Tsugumi; Takahashi, Hideyuki; Tohji, Kazuyuki

2013-12-01

161

High gain 1.3-?m GaInNAs SOA with fast gain dynamics and enhanced temperature stability  

NASA Astrophysics Data System (ADS)

Semiconductor optical amplifiers (SOAs) are a well-established solution of optical access networks. They could prove an enabling technology for DataCom by offering extended range of active optical functionalities. However, in such costand energy-critical applications, high-integration densities increase the operational temperatures and require powerhungry external cooling. Taking a step further towards improving the cost and energy effectiveness of active optical components, we report on the development of a GaInNAs/GaAs (dilute nitride) SOA operating at 1.3?m that exhibits a gain value of 28 dB and combined with excellent temperature stability owing to the large conduction band offset between GaInNAs quantum well and GaAs barrier. Moreover, the characterization results reveal almost no gain variation around the 1320 nm region for a temperature range from 20° to 50° C. The gain recovery time attained values as short as 100 ps, allowing implementation of various signal processing functionalities at 10 Gb/s. The combined parameters are very attractive for application in photonic integrated circuits requiring uncooled operation and thus minimizing power consumption. Moreover, as a result of the insensitivity to heating issues, a higher number of active elements can be integrated on chip-scale circuitry, allowing for higher integration densities and more complex optical on-chip functions. Such component could prove essential for next generation DataCom networks.

Fitsios, D.; Giannoulis, G.; Iliadis, N.; Korpijärvi, V.-M.; Viheriälä, J.; Laakso, A.; Dris, S.; Spyropoulou, M.; Avramopoulos, H.; Kanellos, G. T.; Pleros, N.; Guina, M.

2014-03-01

162

Time-resolved photoluminescence studies of annealed 1.3-?m GaInNAsSb quantum wells  

NASA Astrophysics Data System (ADS)

Time-resolved photoluminescence (PL) was applied to study the dynamics of carrier recombination in GaInNAsSb quantum wells (QWs) emitting near 1.3 ?m and annealed at various temperatures. It was observed that the annealing temperature has a strong influence on the PL decay time, and hence, it influences the optical quality of GaInNAsSb QWs. At low temperatures, the PL decay time exhibits energy dependence (i.e., the decay times change for different energies of emitted photons), which can be explained by the presence of localized states. This energy dependence of PL decay times was fitted by a phenomenological formula, and the average value of E 0, which describes the energy distribution of localized states, was extracted from this fit and found to be smallest ( E 0 = 6 meV) for the QW annealed at 700°C. In addition, the value of PL decay time at the peak energy was compared for all samples. The longest PL decay time (600 ps) was observed for the sample annealed at 700°C. It means that based on the PL dynamics, the optimal annealing temperature for this QW is approximately 700°C.

Baranowski, Michal; Kudrawiec, Robert; Syperek, Marcin; Misiewicz, Jan; Sarmiento, Tomas; Harris, James S.

2014-02-01

163

Three of four GlnR binding sites are essential for GlnR-mediated activation of transcription of the Amycolatopsis mediterranei nas operon.  

PubMed

In Amycolatopsis mediterranei U32, genes responsible for nitrate assimilation formed one operon, nasACKBDEF, whose transcription is induced by the addition of nitrate. Here, we characterized GlnR as a direct transcriptional activator for the nas operon. The GlnR-protected DNA sequences in the promoter region of the nas operon were characterized by DNase I footprinting assay, the previously deduced Streptomyces coelicolor double 22-bp GlnR binding consensus sequences comprising a1, b1, a2, and b2 sites were identified, and the sites were then mutated individually to test their roles in both the binding of GlnR in vitro and the GlnR-mediated transcriptional activation in vivo. The results clearly showed that only three GlnR binding sites (a1, b1, and b2 sites) were required by GlnR for its specific binding to the nas promoter region and efficient activation of the transcription of the nas operon in U32, while the a2 site seemed unnecessary. PMID:23543714

Wang, Ying; Wang, Jing-Zhi; Shao, Zhi-Hui; Yuan, Hua; Lu, Yin-Hua; Jiang, Wei-Hong; Zhao, Guo-Ping; Wang, Jin

2013-06-01

164

Study of nitrogen incorporation into GaInNAs: The role of growth temperature in molecular beam epitaxy  

SciTech Connect

GaInNAs has an important impact on developing GaAs-based optoelectronics and multijunction solar cells, but the complex nature of the nitrogen incorporation into GaInAs is still not fully understood. By combining x-ray diffraction, photoluminescence, reflection high-energy electron diffraction, and photoelectron spectroscopy measurements, we show that nitrogen incorporation is enhanced with increasing growth temperature in the range of 300-450 Degree-Sign C. We study the growth front and show that the surface reconstruction is (1 Multiplication-Sign 3) regardless of growth temperature in this range. The enhanced nitrogen incorporation can be modeled as a thermally activated process with activation energy of about 0.1 eV.

Korpijaervi, V.-M.; Aho, A.; Tukiainen, A.; Laakso, A.; Guina, M. [Optoelectronics Research Centre (ORC), Tampere University of Technology, Tampere 33720 (Finland); Laukkanen, P.; Tuominen, M. [Department of Physics and Astronomy, University of Turku, Turku 20014 (Finland)

2012-07-15

165

Study of nitrogen incorporation into GaInNAs: The role of growth temperature in molecular beam epitaxy  

NASA Astrophysics Data System (ADS)

GaInNAs has an important impact on developing GaAs-based optoelectronics and multijunction solar cells, but the complex nature of the nitrogen incorporation into GaInAs is still not fully understood. By combining x-ray diffraction, photoluminescence, reflection high-energy electron diffraction, and photoelectron spectroscopy measurements, we show that nitrogen incorporation is enhanced with increasing growth temperature in the range of 300-450 °C. We study the growth front and show that the surface reconstruction is (1 × 3) regardless of growth temperature in this range. The enhanced nitrogen incorporation can be modeled as a thermally activated process with activation energy of about 0.1 eV.

Korpijärvi, V.-M.; Aho, A.; Laukkanen, P.; Tukiainen, A.; Laakso, A.; Tuominen, M.; Guina, M.

2012-07-01

166

14GHz GaNAsSb Unitraveling-Carrier 1.3- Photodetectors Grown by RF Plasma-Assisted Nitrogen Molecular Beam Epitaxy  

Microsoft Academic Search

We report on picosecond pulsed response and 3-dB cutoff frequency of 1.3-mum GaNAsSb unitraveling-carrier photodetectors (PDs) grown by molecular beam epitaxy using a radio-frequency plasma-assisted nitrogen source. The 0.1-mum -thick GaNAsSb photoabsorption layer contains 3.5% of N and 9% of Sb, resulting in a bandgap of 0.88 eV. The dark current densities at 0 and -9 V are 6 and

Kian Hua Tan; Soon F. Yoon; Sascha Fedderwitz; A. Stohhr; Wan Khai Loke; Satrio Wicaksono; Tien Khee Ng; M. Weiss; Artur Poloczek; Vitaly Rymanov; Ardhendu S. Patra; Eduward Tangdiongga; Dieter Jager

2009-01-01

167

Effects of rapid thermal annealing conditions on GaInNAs band gap blueshift and photoluminescence intensity  

SciTech Connect

We have studied the effects of various conditions of rapid thermal annealing (RTA) on 10 nm GaInNAs/GaAs single quantum wells (SQWs) with fixed indium concentration and increasing nitrogen content to obtain photoluminescence (PL) in the telecom wavelength regime of 1.3 and 1.5 {mu}m. Specifically, we analyzed the results of annealing for a fixed short time but at different temperatures and for longer times at a fixed temperature. In all experiments, InGaAs SQWs with the same In concentration were used as references. For both RTA conditions, the well-known blueshift of the band gap energy and the PL intensity improvement show trends that reveal that these are unrelated effects. At high RTA temperatures the PL efficiency reaches a maximum and then drops independently of N content. On the contrary, the blueshift experiences a rapid increase up to 700 deg. C (strong blueshift regime) and it saturates above this temperature (weak blueshift regime). Both these blueshift regimes are related to the nitrogen content in the SQWs but in different ways. In the strong blueshift regime, we could obtain activation energy for the blueshift process in the range of 1.25 eV, which increases with N content. Analysis with high-resolution x-ray diffraction (HRXRD) shows that the blueshift experienced in this regime is not due to a stoichiometric change in the QW. In the weak blueshift regime, the blueshift, which is only partly due to In outdiffusion, saturates more slowly the higher the N content. Annealing at the same temperature (600 deg. C) for a longer time shows that the blueshift saturates earlier than the PL intensity and that samples with higher nitrogen experience a larger blueshift. Only a small In outdiffusion for annealing at high temperatures (>650 deg. C) and long duration was observed. However, this modest stoichiometric change does not explain the large blueshift experienced by the GaInNAs SQWs. We conclude that the mechanism responsible for the drastic blueshift after annealing is related to the N content in the QW, while the improvement in PL integrated intensity is uniquely related to the annealing conditions.

Liverini, V.; Rutz, A.; Keller, U.; Schoen, S. [ETH Zurich, Physics Department, Institute of Quantum Electronics, Wolfgang-Pauli-Strasse 16, CH-8093 Zurich (Switzerland); ETH Zurich, FIRST Center for Micro- and Nanoscience, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich (Switzerland)

2006-06-01

168

Enhancement of photoluminescence from GaInNAsSb quantum wells upon annealing: improvement of material quality and carrier collection by the quantum well.  

PubMed

In this study we apply time resolved photoluminescence and contactless electroreflectance to study the carrier collection efficiency of a GaInNAsSb/GaAs quantum well (QW). We show that the enhancement of photoluminescence from GaInNAsSb quantum wells annealed at different temperatures originates not only from (i) the improvement of the optical quality of the GaInNAsSb material (i.e., removal of point defects, which are the source of nonradiative recombination) but it is also affected by (ii) the improvement of carrier collection by the QW region. The total PL efficiency is the product of these two factors, for which the optimal annealing temperatures are found to be ~700 °C and ~760 °C, respectively, whereas the optimal annealing temperature for the integrated PL intensity is found to be between the two temperatures and equals ~720 °C. We connect the variation of the carrier collection efficiency with the modification of the band bending conditions in the investigated structure due to the Fermi level shift in the GaInNAsSb layer after annealing. PMID:23306016

Baranowski, M; Kudrawiec, R; Latkowska, M; Syperek, M; Misiewicz, J; Sarmiento, T; Harris, J S

2013-02-13

169

Optical studies on InAs/InGaAs/GaNAs strain-compensated quantum dots grown on GaAs (0 0 1) by molecular beam epitaxy  

NASA Astrophysics Data System (ADS)

We have investigated the growth of 10 stacked layers of self-assembled InAs quantum dots (QDs) on GaAs (0 0 1) substrates, which were embedded in a combined set of a GaNAs strain-compensating layer (SCL) and an InGaAs strain-reducing layer (SRL). The internal compressive strain induced by each InAs QD layer was compensated by a tensile strain due to a GaNAs SCL. Consequently, the photoluminescence (PL) measured at 30 K showed a narrower linewidth of 60.3 meV for the sample with GaN 0.008As 0.992 SCL compared to 94.2 meV for InAs/GaAs uncontrolled sample due to an improved QD size uniformity. In order to reduce the nominal lattice mismatch at the heterointerface, we propose to insert an InGaAs SRL between the InAs QD layer and GaNAs SCL. We observed a PL peak redshift up to 1230 nm at room temperature, and increased PL intensity for InAs QD/InGaAs SRL/GaNAs SCL samples.

Takata, Ayami; Oshima, Ryuji; Shoji, Yasushi; Okada, Yoshitaka

2009-03-01

170

RESÍDUOS DAS INDÚSTRIAS MADEIREIRAS: UM ESTUDO DE CASO NAS SERRARIAS DE RIO BRANCO - ACRE 1 Lumber Industry Residues: A Case Study of Rio Branco-Acre Sawmills  

Microsoft Academic Search

Resumo: Este estudo aborda o setor madeireiro no município de Rio Branco-Acre. Os objetivos gerais foram levantar e discutir informações sobre os resí duos gerados nas serrarias de Rio Branco, especificamente naqueles localizadas no distrito industrial, com o intuito de subsidiar o planejamento das serrarias quanto ao gerenciamento dos resíduos. Neste contexto, o estudo visou, de forma específica: 1) a

Suelem Marina de Araújo; Rosana Cavalcante dos Santos

171

Test and Evaluation of the Conflict Alert Function (High Altitude) with the NAS Enroute A3d2.1 System.  

National Technical Information Service (NTIS)

This report deals with aircraft trackings for separation violations. It describes the operational evaluation of a collision alert function interfaced with the National Airspace System (NAS) Enroute A3d2.1 system. Tests were conducted in a beacon only high...

F. W. Ranger

1975-01-01

172

CalnNAs Structures Grown by MBE for High-Efficency Solar Cells. Final Report June 25, 1999-August 24, 2002.  

National Technical Information Service (NTIS)

The focus of this work is to improve the quality of GaInNAs by advanced thin-film growth techniques, such as digital-alloy growth techniques and migration-enhanced epitaxy (MEE). The other focus is to further investigate the properties of such materials, ...

C. W. Tu

2003-01-01

173

Effect of multilayer barriers on the optical properties of GaInNAs single quantum-well structures grown by metalorganic vapor phase epitaxy  

NASA Astrophysics Data System (ADS)

We report on the effects of combined strain-compensating and strain-mediating layers of various widths on the optical properties of 1.3 ?m GaInNAs/GaAs single quantum well structures grown by metalorganic vapor phase epitaxy (MOVPE). While the emission wavelength of GaInNAs/GaAs quantum wells can be redshifted by the adoption of strain-compensated GaNAs layers, the material quality is degraded by the increased stress at the well/barrier interface. This detrimental effect can be cured by inserting a strain-mediating InGaAs layer between them. Contrary to what is expected, however, the emission wavelength is blueshifted by the insertion of the InGaAs layer, which is attributed to the reduced N incorporation due to the improved interface quality. Our results indicate that the optical properties of MOVPE-grown GaInNAs/GaAs quantum wells can be optimized in quantum efficiency and emission wavelength by combination of strain-compensating and strain-mediating layers with suitable characteristics.

Sun, H. D.; Clark, A. H.; Calvez, S.; Dawson, M. D.; Kim, K. S.; Kim, T.; Park, Y. J.

2005-07-01

174

Comparative study of the carcinogenic activities of nas and some chemical carcinogens when introduced into the buccal pouch of the Syrian hamster*  

PubMed Central

Studies were carried out on the carcinogenic effects of nas, 7,12-dimethylbenz-[a]anthracene (DMBA), DMBA+nas, dimethylnitrosamine (DMNA), diethylnitrosamine (DENA), and N-methyl-N-nitrosourea (MNU) when introduced into the buccal pouch of the Syrian hamster. Nas alone induced no tumours in the buccal pouch but tumours at other sites occurred in 18.8% of the treated animals, compared with 4.4% of the controls. Three of 11 hamsters treated with DMBA alone developed tumours. No tumours appeared in the buccal pouch following treatment with DMBA + nas but they developed at other sites in 6 of the 11 hamsters treated. DMNA and DENA induced no macroscopic changes in the mucous membrane of the buccal pouch. Following DMNA administration, tumours developed only in the liver; no tumours developed following the application of DENA. Tumours developed at various sites, including the buccal pouch, in 20 of the 25 hamsters treated with MNU. ImagesFig. 1Fig. 2Fig. 3Fig. 4Fig. 5Fig. 6

Milievskaja, I. L.; Kiseleva, N. S.

1976-01-01

175

Mobilidade e Vulnerabilidade nos Espaços de Vida de Campinas  

Microsoft Academic Search

Resumo A vida nas metrópoles brasileiras tem sofrido alterações significativas nos últimos 30 anos, produzindo novos padrões espaciais e sociodemográficos que incidem diretamente na qualidade e no padrão de vida das pessoas. Dois traços desta nova forma metropolitana são especialmente relevantes para compreender estas transformações e suas implicações: a mobilidade e a vulnerabilidade. Nos dois casos, a problemática ambiental está

Eduardo Marandola Jr

176

The solution of linear systems of equations with a structural analysis code on the NAS CRAY-2  

NASA Technical Reports Server (NTRS)

Two methods for solving linear systems of equations on the NAS Cray-2 are described. One is a direct method; the other is an iterative method. Both methods exploit the architecture of the Cray-2, particularly the vectorization, and are aimed at structural analysis applications. To demonstrate and evaluate the methods, they were installed in a finite element structural analysis code denoted the Computational Structural Mechanics (CSM) Testbed. A description of the techniques used to integrate the two solvers into the Testbed is given. Storage schemes, memory requirements, operation counts, and reformatting procedures are discussed. Finally, results from the new methods are compared with results from the initial Testbed sparse Choleski equation solver for three structural analysis problems. The new direct solvers described achieve the highest computational rates of the methods compared. The new iterative methods are not able to achieve as high computation rates as the vectorized direct solvers but are best for well conditioned problems which require fewer iterations to converge to the solution.

Poole, Eugene L.; Overman, Andrea L.

1988-01-01

177

Thermo-responsive shell cross-linked PMMA-b-P(NIPAAm-co-NAS) micelles for drug delivery.  

PubMed

Thermo-responsive amphiphilic poly(methyl methacrylate)-b-poly(N-isopropylacrylamide-co-N-acryloxysuccinimide) (PMMA-b-P(NIPAAm-co-NAS)) block copolymer was synthesized by successive RAFT polymerizations. The uncross-linked micelles were facilely prepared by directly dissolving the block copolymer in an aqueous medium, and the shell cross-linked (SCL) micelles were further fabricated by the addition of ethylenediamine as a di-functional cross-linker into the micellar solution. Optical absorption measurements showed that the LCST of uncross-linked and cross-linked micelles was 31.0°C and 40.8°C, respectively. Transmission electron microscopy (TEM) showed that both uncross-linked and cross-linked micelles exhibited well-defined spherical shape in aqueous phase at room temperature, while the SCL micelles were able to retain the spherical shape with relatively smaller dimension even at 40°C due to the cross-linked structure. In vitro drug release study demonstrated a slower and more sustained drug release behavior from the SCL micelles at high temperature as compared with the release profile of uncross-linked micelles, indicating the great potential of SCL micelles developed herein as novel smart carriers for controlled drug release. PMID:21896321

Chang, Cong; Wei, Hua; Wu, De-Qun; Yang, Bin; Chen, Ni; Cheng, Si-Xue; Zhang, Xian-Zheng; Zhuo, Ren-Xi

2011-11-28

178

The NAS parallel benchmarks  

NASA Technical Reports Server (NTRS)

A new set of benchmarks was developed for the performance evaluation of highly parallel supercomputers. These benchmarks consist of a set of kernels, the 'Parallel Kernels,' and a simulated application benchmark. Together they mimic the computation and data movement characteristics of large scale computational fluid dynamics (CFD) applications. The principal distinguishing feature of these benchmarks is their 'pencil and paper' specification - all details of these benchmarks are specified only algorithmically. In this way many of the difficulties associated with conventional benchmarking approaches on highly parallel systems are avoided.

Bailey, David (editor); Barton, John (editor); Lasinski, Thomas (editor); Simon, Horst (editor)

1993-01-01

179

The Nas Parallel Benchmarks  

Microsoft Academic Search

A new set of benchmarks has been developed for the performance evaluation of highly parallel supercomputers. These benchmarks consist of five parallel kernels and three simulated application benchmarks. Together theymimic the computation and data movement characteristics of large scale computational fluid dynamics (CFD) applications.The principal distinguishing feature of these benchmarks is their penciland paper specification---all details of these benchmarks are

D. Bailey; E. Barszcz; J. Barton; D. Browning; R. Carter; L. Dagum

1994-01-01

180

Caracterização das propriedades espaciais, temporais e físicas de Relâmpagos e Sistemas Convectivos de Mesoescala  

Microsoft Academic Search

The objective of this work is to present the cloud-ground lightning spatial and temporal distribution and the relationship between electrical discharges and the physical properties of the Mesoescale Convective System (MSC) for the determination of potential forecaster parameters of atmosphere electrical activity. This work combined data from GOES geostationary satellite infrared channels with cloud-ground lightning from the ground network supplied

Enrique Vieira Mattos

181

Principais Programas Espaciais NA Area de Microondas (Principal Space Programs in the Area of Microwaves).  

National Technical Information Service (NTIS)

The following space programs are described: SEASAT SIR-A, SIR-A, SIR-B, RADARSAT (Canada), ESA/ERS-1 (Europe), MOS-1 and ERS-1 (Japan), and SAMEX, TOPEX, NASA (USA). The space programs are all related to microwave sensors and remote sensing.

J. F. Dallemand R. A. Lamparelli

1987-01-01

182

Recent results of plasma research activities at the Instituto de Pesquisas Espaciais  

Microsoft Academic Search

Results of experiments performed at the Institute for Space Research (INPE) are reported. An enrichment of 390 percent of carbon isotopes was achieved in the plasma centrifuge. The role of ion-acoustic turbulence in the formation of double layers was experimentally investigated. The turbulent spectrum was measured and agrees quite well with the prediction of the modified Kadomtsev renormalized theory. The

J. J. Barroso; J. A. Bittencourt; R. S. Dallaqua; E. Delbosco; A. Ferreira; J. L. Ferreira; G. P. Galvao; R. M. O. Galvao; G. O. Ludwig; A. Montes

1987-01-01

183

Intrinsic temperature sensitivities of 1.3 ?m GaInNAs\\/GaAs, InGaAsP\\/InP and AlGaInAs\\/InP-based semiconductor lasers  

Microsoft Academic Search

The apparent temperature stability of GaInNAs-based lasers is attributed to significant defect current. By removing this current, GaInNAs devices have a similar temperature dependence to InGaAsP devices whilst AlGaInAs devices are more thermally stable.

S. J. Sweeney; R. Fehse; A. R. Adams; H. Riechert

2003-01-01

184

Molecular beam epitaxy of GaNAs alloys with high As content for potential photoanode applications in hydrogen production  

SciTech Connect

The authors have succeeded in growing GaN1?xAsx alloys over a large composition range (0 < x < 0.8) by plasma-assisted molecular beam epitaxy. The enhanced incorporation of As was achieved by growing the films with high As{sub 2} flux at low (as low as 100 C) growth temperatures, which is much below the normal GaN growth temperature range. Using x-ray and transmission electron microscopy, they found that the GaNAs alloys with high As content x > 0.17 are amorphous. Optical absorption measurements together with x-ray absorption and emission spectroscopy results reveal a continuous gradual decrease in band gap from -3.4 to < 1 eV with increasing As content. The energy gap reaches its minimum of -0.8 eV at x - 0.8. The composition dependence of the band gap of the crystalline GaN{sub 1?x}As{sub x} alloys follows the prediction of the band anticrossing model (BAC). However, our measured band gap of amorphous GaN{sub 1?x}As{sub x} with 0.3 < x < 0.8 are larger than that predicted by BAC. The results seem to indicate that for this composition range the amorphous GaN{sub 1?x}As{sub x} alloys have short-range ordering that resembles random crystalline GaN{sub 1?x}As{sub x} alloys. They have demonstrated the possibility of the growth of amorphous GaN{sub 1?x}As{sub x} layers with variable As content on glass substrates

Novikov, S. V.; Staddon, C. R.; Foxon, C. T.; Yu, K. M.; Broesler, R.; Hawkridge, M.; Liliental-Weber, Z.; Walukiewicz, W.; Denlinger, J.; Demchenko, I.

2009-10-06

185

Accelerations experienced during low-G flight of Black Brant VC (NAS 21.015) on 4 October 1974  

NASA Technical Reports Server (NTRS)

This investigation was to determine whether a Black Brant VC (BBVC) sounding rocket equipped with the Goddard Space Flight Center (GSFC) rate control system (RCS) would produce g-levels which are satisfactory for space processing. Accelerations measured by the Marshall Space Flight Center (MSFC) low-g accelerometer system (LGAS) were compared with accelerations calculated from measured payload RCS gyro data during a low-g flight of BBVC NAS 21.015 at White Sands Missile Range, N.M., on October 4, 1974. Accelerations of up to 0.0002 g existed at the LGAS accelerometers from 70 through 420 sec (5.8 min), with the exception of a spike at 101 sec of 0.0004 g which occurred when the RCS was activated the second time. Accelerations of 0.0001 g existed from 140 through 400 sec (4.3 min). Accelerations of 0.0002 g along the roll axis up to 150 sec and of 0.0015 g in the lateral plane at about 135 sec are being investigated by GSFC. They may be associated with leaking thruster valves or a leak in one of the heat pipe experiments. The vehicle rate buildup each time after the RCS nulls out are also being investigated by GSFC. This rate caused most of the 0.0001 g acceleration experienced after 150 sec into the flight. Aerodynamic drag produced no significant accelerations after about 80 sec. The principal conclusion was that the BBVC with the GSFC RCS produces g-levels satisfactory for space processing.

Kissel, R.

1975-01-01

186

Nonlinear dynamics of non-equilibrium holes in p-type modulation-doped GaInNAs/GaAs quantum wells  

PubMed Central

Nonlinear charge transport parallel to the layers of p-modulation-doped GaInNAs/GaAs quantum wells (QWs) is studied both theoretically and experimentally. Experimental results show that at low temperature, T = 13 K, the presence of an applied electric field of about 6 kV/cm leads to the heating of the high mobility holes in the GaInNAs QWs, and their real-space transfer (RST) into the low-mobility GaAs barriers. This results in a negative differential mobility and self-generated oscillatory instabilities in the RST regime. We developed an analytical model based upon the coupled nonlinear dynamics of the real-space hole transfer and of the interface potential barrier controlled by space-charge in the doped GaAs layer. Our simulation results predict dc bias-dependent self-generated current oscillations with frequencies in the high microwave range.

2011-01-01

187

Weather Requirements and Procedures for Step 1: High Altitude Long Endurance (HALE) Unmanned Aircraft System (UAS) Flight Operations in the National Air Space (NAS)  

NASA Technical Reports Server (NTRS)

This cover sheet is for version 2 of the weather requirements document along with Appendix A. The purpose of the requirements document was to identify and to list the weather functional requirements needed to achieve the Access 5 vision of "operating High Altitude, Long Endurance (HALE) Unmanned Aircraft Systems (UAS) routinely, safely, and reliably in the National Airspace System (NAS) for Step 1." A discussion of the Federal Aviation Administration (FAA) references and related policies, procedures, and standards is provided as basis for the recommendations supported within this document. Additional procedures and reference documentation related to weather functional requirements is also provided for background. The functional requirements and related information are to be proposed to the FAA and various standards organizations for consideration and approval. The appendix was designed to show that sources of flight weather information are readily available to UAS pilots conducting missions in the NAS. All weather information for this presentation was obtained from the public internet.

2007-01-01

188

The influence of As/III pressure ratio on nitrogen nearest-neighbor environments in as-grown GaInNAs quantum wells  

SciTech Connect

The energy fine structure, corresponding to different nitrogen nearest-neighbor environments, was observed in contactless electroreflectance (CER) spectra of as-grown GaInNAs quantum wells (QWs) obtained at various As/III pressure ratios. In the spectral range of the fundamental transition, two CER resonances were detected for samples grown at low As pressures whereas only one CER resonance was observed for samples obtained at higher As pressures. This resonance corresponds to the most favorable nitrogen nearest-neighbor environment in terms of the total crystal energy. It means that the nitrogen nearest-neighbor environment in GaInNAs QWs can be controlled in molecular beam epitaxy process by As/III pressure ratio.

Kudrawiec, R.; Poloczek, P.; Misiewicz, J. [Institute of Physics, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw (Poland); Korpijaervi, V.-M.; Laukkanen, P.; Pakarinen, J.; Dumitrescu, M.; Guina, M.; Pessa, M. [Optoelectronics Research Centre, Tampere University of Technology, FIN-33101 Tampere (Finland)

2009-12-28

189

The influence of As/III pressure ratio on nitrogen nearest-neighbor environments in as-grown GaInNAs quantum wells  

NASA Astrophysics Data System (ADS)

The energy fine structure, corresponding to different nitrogen nearest-neighbor environments, was observed in contactless electroreflectance (CER) spectra of as-grown GaInNAs quantum wells (QWs) obtained at various As/III pressure ratios. In the spectral range of the fundamental transition, two CER resonances were detected for samples grown at low As pressures whereas only one CER resonance was observed for samples obtained at higher As pressures. This resonance corresponds to the most favorable nitrogen nearest-neighbor environment in terms of the total crystal energy. It means that the nitrogen nearest-neighbor environment in GaInNAs QWs can be controlled in molecular beam epitaxy process by As/III pressure ratio.

Kudrawiec, R.; Korpijärvi, V.-M.; Poloczek, P.; Misiewicz, J.; Laukkanen, P.; Pakarinen, J.; Dumitrescu, M.; Guina, M.; Pessa, M.

2009-12-01

190

Contactless electroreflectance study of band bending in Be-doped GaInNAs/GaAs quantum wells: The origin of photoluminescence enhancement  

NASA Astrophysics Data System (ADS)

Contactless electroreflectance (CER) has been applied to study band bending in Be-doped GaInNAs/GaAs quantum wells (QWs). It has been shown that (i) the sign of GaAs-related CER signal changes from positive to negative due to Be-doping and (ii) QW-related CER resonances disappear for Be-doped QWs whereas they are clearly observed for un-doped QWs. The two observations indicate a Be-related shift in the Fermi level above the hole levels in the QW region, i.e., the change in band bending in this system. The results point out that the experimentally-observed enhancement in QW photoluminescence upon Be-doping is associated with a better collection/confinement of photogenerated carriers by the Be-doped GaInNAs QW.

Kudrawiec, R.; Gladysiewicz, M.; Misiewicz, J.; Korpijärvi, V.-M.; Pakarinen, J.; Puustinen, J.; Laukkanen, P.; Laakso, A.; Guina, M.; Dumitrescu, M.; Pessa, M.

2010-07-01

191

Optimal Blast Condition for the Inner Surface of Mass Produced NAS Battery Cylindrical Aluminum Cell Containers as Pretreatment of Thermal Spraying  

Microsoft Academic Search

The relationship between roughness caused by blasting and adhesion of spray coatings on aluminum container substrates was studied through various experiments as part of measures for improving the adhesion of the 75mass%Cr-Fe alloy plasma spray coating for sulfi dation corrosion resistance, which is applied on the inner surface of cylindrical Al containers of high-temperature type NAS batteries. Surface roughness of

Takashi Ando; Yoshio Harada

2007-01-01

192

Inactivation of gltB Abolishes Expression of the Assimilatory Nitrate Reductase Gene (nasB) in Pseudomonas putida KT2442  

PubMed Central

By using mini-Tn5 transposon mutagenesis, random transcriptional fusions of promoterless bacterial luciferase, luxAB, to genes of Pseudomonas putida KT2442 were generated. Insertion mutants that responded to ammonium deficiency by induction of bioluminescence were selected. The mutant that responded most strongly was genetically analyzed and is demonstrated to bear the transposon within the assimilatory nitrate reductase gene (nasB) of P. putida KT2442. Genetic evidence as well as sequence analyses of the DNA regions flanking nasB suggest that the genes required for nitrate assimilation are not clustered. We isolated three second-site mutants in which induction of nasB expression was completely abolished under nitrogen-limiting conditions. Nucleotide sequence analysis of the chromosomal junctions revealed that in all three mutants the secondary transposon had inserted at different sites in the gltB gene of P. putida KT2442 encoding the major subunit of the glutamate synthase. A detailed physiological characterization of the gltB mutants revealed that they are unable to utilize a number of potential nitrogen sources, are defective in the ability to express nitrogen starvation proteins, display an aberrant cell morphology under nitrogen-limiting conditions, and are impaired in the capacity to survive prolonged nitrogen starvation periods.

Eberl, Leo; Ammendola, Aldo; Rothballer, Michael H.; Givskov, Michael; Sternberg, Claus; Kilstrup, Mogens; Schleifer, Karl-Heinz; Molin, S?ren

2000-01-01

193

A estabilidade dos PAHS em função da energia da radiação interestelar nas faixas UV e raios-X  

NASA Astrophysics Data System (ADS)

A nebulosa CRL 618, uma proto-nebulosa planetária cuja nuvem molecular espessa envolve uma estrela B0, contém uma grande quantidade de C2H2 e CH4. Estas moléculas são consideradas os tijolos da criação de grandes moléculas carbonadas como os Hidrocarbonetos Policíclicos Aromáticos (PAHs). Esta nebulosa, por estar exposta a intensos campos de UV e Raios-X, é uma região de fotodissociação molecular que propicia a formação de novas moléculas, confirmada pela presença de C4H2 e C6H6 (Benzeno), que é a unidade básica dos PAHs. Atribui-se a esta família de moléculas orgânicas duas propriedades fundamentais, a resistência para sobreviver ao campo de radiação UV interestelar e a geração das bandas de emissão não identificadas (UIR) observadas no infravermelho. No entanto, alguns autores questionam a resistência dos PAHs ao campo de radiação UV interestelar. Empregando a técnica de Espectrometria de Massas por Tempo de Vôo, no modo de coincidência fotoelétron-fotoíon, estudamos a ionização e fragmentação das seguintes moléculas: Benzeno, Benzeno deuterado, Naftaleno, Antraceno e Fenantreno. Utilizamos uma fonte de Hélio monocromática em 21,21 eV (584,5 Å) e a radiação Síncroton do Laboratório Nacional de Luz Síncroton (LNLS) em diferentes energias nas proximidades da borda do C 1s ( 290 eV). Comprovamos a estabilidade dos PAHs sob ação de UV (21,21 eV), onde eles apresentam um baixo nível de fotodissociação, produzindo fragmentos ionizados com rendimento total na ordem de 5 por cento em relação ao íon molecular pai. Entretanto, em altas energias, na faixa de Raios-X, a quebra destas moléculas torna-se mais intensa, com a produção de muitos fragmentos. Como uma das rotas de fragmentação do Naftaleno é [(C10H8) = > (C6H6+) + (C4H2) + (e-)], e como temos as evidências observacionais da existência do C4H2 e C6H6 na nebulosa CRL 618, sugerimos que este ambiente também possui o Naftaleno.

Pinotti, R.; Costa, R. K.; Boechat-Roberty, H. M.; Lago, A.; Souza, G. B.

2003-08-01

194

The effect of spacer layer thickness on vertical alignment of InGaAs/GaNAs quantum dots grown on GaAs(3 1 1)B substrate  

NASA Astrophysics Data System (ADS)

We fabricated multiple stacked self-organized InGaAs quantum dots (QDs) on GaAs (3 1 1)B substrate by atomic hydrogen-assisted molecular beam epitaxy (H-MBE) to realize an ordered three-dimensional QD array. High quality stacked QDs with good size uniformity were achieved by using strain-compensation growth technique, in which each In 0.35Ga 0.65As QD layer was embedded by GaNAs strain-compensation layer (SCL). In order to investigate the effect of spacer layer thickness on vertical alignment of InGaAs/GaNAs QDs, the thickness of GaNAs SCL was varied from 40 to 20 nm. We observed that QDs were vertically aligned in [3 1 1] direction when viewed along [0 1 -1], while the alignment was inclined when viewed along [-2 3 3] for all samples with different SCL thickness. This is due to their asymmetric shape along [-2 3 3] with two different dominant facets thereby the local strain field around QD extends further outward from the lower-angle facet. Furthermore, the inclination angle of vertical alignment QDs became monotonously smaller from 22° to 2° with decreasing SCL thickness from 40 to 20 nm. These results suggest that the strain field extends asymmetrically resulting in vertically tilted alignment of QDs for samples with thick SCLs, while the propagated local strain field is strong enough to generate the nucleation site of QD formation just above lower QD in the sample with thinner SCLs.

Shoji, Yasushi; Oshima, Ryuji; Takata, Ayami; Okada, Yoshitaka

2010-09-01

195

Effects of the 5HT 1B receptor antagonist NAS181 on extracellular levels of acetylcholine, glutamate and GABA in the frontal cortex and ventral hippocampus of awake rats: A microdialysis study  

Microsoft Academic Search

The purpose of this study was to investigate the effects of the 5-HT1B receptor antagonist NAS-181 ((R)-(+)-2-(3-morpholinomethyl-2H-chromen-8-yl) oxymethyl-morpholine methanesulfonate) on cholinergic, glutamatergic and GABA-ergic neurotransmission in the rat brain in vivo. Extracellular levels of acetylcholine, glutamate and GABA were monitored by microdialysis in the frontal cortex (FC) and ventral hippocampus (VHipp) in separate groups of freely moving rats. NAS-181 (1,

Xiao Jing Hu; Fu-Hua Wang; Carina Stenfors; Sven Ove Ögren; Jan Kehr

2007-01-01

196

Validez en la evaluación de escalas  

Microsoft Academic Search

Scales are of particular importance when the variable or the entity that we pretend to mea- sure is subjective, that is, there is a high degree of variability among its defi nition and its components. Among the qualities that a measurement instrument must have are its utility, reliability, and validity. Validity allows us to test hypothesis and make inferences about

Julio Alejandro; Carlos Gómez-Restrepo

197

Optical properties of multi-stacked InGaAs/GaNAs quantum dot solar cell fabricated on GaAs (311)B substrate  

SciTech Connect

Quantum dot solar cells (QDSCs) comprised of 10 stacked pairs of strain-compensated InGaAs/GaNAs QD structure have been fabricated by atomic hydrogen-assisted molecular beam epitaxy. A homogeneous and high-density QD array structure with improved in-plane ordering and total density of {approx}10{sup 12} cm{sup -2} has been achieved on GaAs (311)B grown at 460 Degree-Sign C after stacking. The external quantum efficiency (EQE) of InGaAs/GaNAs QDSC increases in the longer wavelength range due to additive contribution from QD layers inserted in the intrinsic region. The short-circuit current density measured for QDSC is 17.2 mA/cm{sup 2} compared to 14.8 mA/cm{sup 2} of GaAs reference cell. Further, an increase in EQE due to photocurrent production by 2-step photon absorption has been observed at room temperature though it is still small at around 0.1%.

Shoji, Yasushi [Research Center for Advanced Science and Technology (RCAST), University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 (Japan); Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Akimoto, Katsuhiro [Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Okada, Yoshitaka [Research Center for Advanced Science and Technology (RCAST), University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 (Japan)

2012-09-15

198

Photoreflectance spectroscopy of semiconductor structures at hydrostatic pressure: A comparison of GaInAs/GaAs and GaInNAs/GaAs single quantum wells  

NASA Astrophysics Data System (ADS)

The pressure dependence of optical transitions in Ga 0.64In 0.36As/GaAs and Ga 0.64In 0.36N 0.01As 0.99/GaAs single quantum well (SQW) structures were studied in photoreflectance (PR) spectroscopy. In order to apply high hydrostatic pressure, up to ˜11 kbar, the liquid-filled clamp-pressure cell with a sapphire window for optical access has been adopted in the PR set-up with the so called 'bright configuration'. It has been found that the linear hydrostatic pressure coefficient for the ground state transition are equal to 8.6 and 7.3 meV/kbar for the GaInAs/GaAs and GaInNAs/GaAs SQWs, respectively. This result shows that the incorporation of only 1% of N atoms into GaInAs/GaAs leads to ˜15% decrease in the pressure coefficient. In addition, a non-linearity in the pressure dependence of the ground state transition has been resolved for the GaInNAs/GaAs SQW.

Kudrawiec, R.; Misiewicz, J.

2006-10-01

199

Reduction in Turn-on Voltage in GaInNAs and InGaAs-Based Double-Heterojunction Bipolar Transistors  

NASA Astrophysics Data System (ADS)

A new quaternary material of GaInNAs has been proposed as base material for GaAs-based double-heterojunction bipolar transistors (DHBTs). The used InGaAs as base material results in the lower band gap energy of the base layer in heterojunction bipolar transistors (HBTs) followed by a smaller turn-on voltage. However, the compressive strain induced by the InGaAs grown on GaAs diminishes the influence of indium-addition induced band gap energy reduction, and thus abate turn-on voltage reduction. By incorporating suitable amounts of indium (In) and nitrogen (N) into GaAs, a smaller band gap material of GaInNAs lattice-matched to GaAs substrate can be obtained. In this study, N-p-n InGaP/Ga0.985In0.015N0.005As0.995/GaAs DHBTs have been demonstrated. A turn-on voltage reduction of 215 mV compared to that of the conventional HBT with a GaAs base layer was obtained. The device has a peak current gain of 85 and shows good high-frequency characteristics of fT and fMAX, which are both higher than 40 GHz

Wu, Cheng-Hsien; Su, Yan-Kuin; Wei, Shang-Chin; Chang, Shoou-Jinn; Sio, Chi-Cheong; Chen, Wei-Chang

2004-04-01

200

A model for the bandgap energy of the dilute nitride InGaNAs alloys by modifying simplified coherent potential approximation  

NASA Astrophysics Data System (ADS)

In this paper, a model describing the bandgap energy of the dilute nitride alloy InxGa1-xNyAs1-y is developed based on the modification of simplified coherent potential approximation (MSCPA) and the band anti-crossing model (BAC). The parameters in the model are obtained by fitting the experimental bandgap energies of the ternary alloys InGaAs, InGaN, GaNAs and InNAs. It is found that the results agree well with the experimental data. We also find that although the bandgap energies of InxGa1-xNyAs1-y and InxGa1-xAs can be calculated by using MSCPA, the physical mechanisms for the bandgap evolution of InxGa1-xNyAs1-y and InxGa1-xAs are very different. In addition, it is found that the model in this work may be used in a larger composition range than the BAC model.

Zhao, Chuan-Zhen; Qu, You-Yang; Wei, Tong; Sun, Xiao-Dong; Wang, Sha-Sha; Lu, Ke-Qing

2014-03-01

201

Numerical study on gain and optical properties of AlGaInAs, InGaNAs, and InGaAsP material systems for 1.3-?m semiconductor lasers  

Microsoft Academic Search

In reference to real devices fabricated in laboratories, the optical properties of AlGaInAs, InGaNAs, and InGaAsP semiconductor material systems for 1.3-?m semiconductor lasers are systematically studied. Simulation results show that both the AlGaInAs\\/InP and InGaNAs\\/GaAs material systems have better gain performance and smaller transparency carrier density than the InGaAsP\\/InP material system. For the AlGaInAs\\/InP material system, the characteristic temperature is

Yen-Kuang Kuo; Sheng-Horng Yen; Ming-Wei Yao; Mei-Ling Chen; Bo-Ting Liou

2007-01-01

202

Hydroxylamine assimilation by Rhodobacter capsulatus E1F1. requirement of the hcp gene (hybrid cluster protein) located in the nitrate assimilation nas gene region for hydroxylamine reduction.  

PubMed

Rhodobacter capsulatus E1F1 grows phototrophically with nitrate as nitrogen source. Using primers designed for conserved motifs in bacterial assimilatory nitrate reductases, a 450-bp DNA was amplified by PCR and used for the screening of a genomic library. A cosmid carrying an insert with four SalI fragments of 2.8, 4.1, 4.5, and 5.8 kb was isolated, and DNA sequencing revealed that it contains a nitrate assimilation (nas) gene region, including the hcp gene coding for a hybrid cluster protein (HCP). Expression of hcp is probably regulated by a nitrite-sensitive repressor encoded by the adjacent nsrR gene. A His(6)-HCP was overproduced in Escherichia coli and purified. HCP contained about 6 iron and 4 labile sulfide atoms per molecule, in agreement with the presence of both [2Fe-2S] and [4Fe-2S-2O] clusters, and showed hydroxylamine reductase activity, forming ammonia in vitro with methyl viologen as reductant. The apparent K(m) values for NH(2)OH and methyl viologen were 1 mM and 7 microM, respectively, at the pH and temperature optima (9.3 and 40 degrees C). The activity was oxygen-sensitive and was inhibited by sulfide and iron reagents. R. capsulatus E1F1 grew phototrophically, but not heterotrophically, with 1 mM NH(2)OH as nitrogen source, and up to 10 mM NH(2)OH was taken up by anaerobic resting cells. Ammonium was transiently accumulated in the media, and its assimilation was prevented by L-methionine-D,L-sulfoximine, a glutamine synthetase inhibitor. In addition, hydroxylamine- or nitrite-grown cells showed the higher hydroxylamine reductase activities. However, R. capsulatus B10S, a strain lacking the whole hcp-nas region, did not grow with 1 mM NH(2)OH. Also, E. coli cells overproducing HCP tolerate hydroxyl-amine better during anaerobic growth. These results suggest that HCP is involved in assimilation of NH(2)OH, a toxic product that could be formed during nitrate assimilation, probably in the nitrite reduction step. PMID:15322098

Cabello, Purificación; Pino, Carmen; Olmo-Mira, M Francisca; Castillo, Francisco; Roldán, M Dolores; Moreno-Vivián, Conrado

2004-10-29

203

Reliability and Validity of the Novaco Anger Scale and Provocation Inventory (NAS-PI) and State-Trait Anger Expression Inventory-2 (STAXI-2) in Hispanic and Non-Hispanic White Student Samples  

ERIC Educational Resources Information Center

This project tested the State-Trait Anger Expression Inventory-2 (STAXI-2) and the Novaco Anger Scale-Provocation Inventory (NAS-PI) in a sample of U.S. Hispanic (n = 257) and U.S. non-Hispanic White (n = 246) undergraduate students. Internal consistency, subscale correlations, convergent validity with the Multidimensional Anger Inventory (MAI),…

Culhane, Scott E.; Morera, Osvaldo F.

2010-01-01

204

Nanoanalytical quantification of the nitrogen content in Ga(NAs)/GaAs by using transmission electron microscopy in combination with refined structure factor calculation  

SciTech Connect

We have studied systematically the nitrogen content in Ga(NAs)/GaAs quantum wells by (002) dark-field transmission electron microscopy (TEM). The nitrogen contents derived from this analysis, when assuming that all the atoms occupy their unperturbed positions in a virtual crystal, deviate significantly from the nitrogen contents we derive for the same samples by other methods; for example, high-resolution x-ray diffraction (XRD) and dynamical simulation of those XRD patterns. The nitrogen causes a significant local strain in the crystal and can accordingly displace the neighboring atoms dramatically. We show that, if the structure factor of the crystals is recalculated, taking these static displacements of the Ga atoms into account, the composition derived from the TEM analysis with that from XRD is in perfect agreement. It is hence necessary for tetragonally distorted crystals that have mixed sublattices containing atoms with different covalent radii to take these static displacements into account when quantification of the composition from dark-field or high-resolution TEM images is aimed for.

Volz, K.; Rubel, O.; Torunski, T.; Baranovskii, S.D.; Stolz, W. [Material Sciences Center and Department of Physics, Philipps University Marburg, 35032 Marburg (Germany)

2006-02-20

205

Enhancement in photoluminescence from 1 eV GaInNAs epilayers subject to 7 MeV electron irradiation  

NASA Astrophysics Data System (ADS)

We have investigated the influence of 7 MeV electron irradiation (1014-1015 cm-2 range) and subsequent rapid thermal annealing (RTA) on luminescence efficiency of nearly lattice-matched 1 eV GaInNAs-on-GaAs epilayers, grown by molecular beam epitaxy. The study has been done by means of 9 K photoluminescence (PL) and 300 K photoreflectance (PR) spectroscopy. Electron irradiation was found to directly promote a notable increase in PL intensity. A further PL enhancement, remarkable at the higher annealing temperature, has been seen upon two RTA stages (at 800 and 900 °C) applied to irradiated samples as compared to a non-irradiated sample. This irradiation-promoted PL enhancement upon annealing occurred with a small additional blue-shift of PL for the lower temperature-annealed samples but no additional shift in PL was noted for the higher temperature-annealed sample. The additional annealing-induced PL blue-shift was mainly due to an irradiation-promoted enhancement in In-N bonds formation, whose magnitude does not appear to depend on dose within the studied range.

Pavelescu, E.-M.; Kudrawiec, R.; B?l???eanu, N.; Spânulescu, S.; Dumitrescu, M.; Guina, M.

2013-02-01

206

Pratt and Whitney/Boeing Engine Validation of Noise Reduction Concepts: Final Report for NASA Contract NAS3-97144, Phase 1  

NASA Technical Reports Server (NTRS)

Major airports in the world's air transportation systems face a serious problem in providing greater capacity to meet the ever increasing demands of air travel. This problem could be relieved if airports are allowed to increase their operating time, now restricted by curfews and by relaxing present limits on takeoffs and landings. The key operational issue in extending the present curfews is noise. In response to these increasing restrictive noise regulations, NASA has launched a program to validate through engine testing, noise reduction concepts and technologies that have evolved from the Advanced Subsonic Technologies (AST) Noise Reduction Program. The goal of this AST program was to develop and validate technology that reduces engine noise and improves nacelle suppression effectiveness relative to 1992 technology. Contract NAS3-97144 titled "Engine Validation of Noise Reduction Concepts" (EVNRC) was awarded to P&W on August 12, 1997 to conduct full scale noise reduction tests in two Phases on a PW4098 engine. The following Section 1.2 provides a brief description of the overall program. The remainder of this report provides a detailed documentation of Phase I of the program.

Mathews, Douglas; Bock, Larry A.; Bielak, Gerald W.; Dougherty, R. P.; Premo, John W.; Scharpf, Dan F.; Yu, Jia

2014-01-01

207

Explorando a Multidimensionalidade da Kd Tree para Suporte a Temporalidade em Dados Espaciais Vetoriais do Tipo Ponto  

Microsoft Academic Search

The representation of time in geographic information systems (GIS) has been subject of intense investigation in late years. Actual research involves from modeling techniques for spatio-temporal representation of reality to spatio-tempor al data structures and file organizations. In this paper, we propose to explore the multidimensional structure of both the Kd-Tree and the Adaptive Kd-Tree in order to keep the

Leonardo Rodriguez Heredia; Cirano Iochpe; João Comba

2003-01-01

208

Optimization of GaInNAs quantum-well vertical-cavity surface-emitting laser emitting at 2.33 ?m  

NASA Astrophysics Data System (ADS)

In the present paper, a comprehensive computer simulation is used to determine optimal structure of the InP-based GaInNAs quantum-well (QW) active region and to investigate a possibility of reaching room-temperature (RT) continuous-wave (CW) single-fundamental-mode 2.33-?m operation of vertical-cavity surface-emitting laser (VCSEL) with such an active region. From among various considered InP-based active regions, the one with the Ga0.15In0.85N0.015As0.985/Al0.138Ga0.332In0.530As QW, i.e. with barriers lattice matched to InP, seems to be optimal for the 2.33-?m VCSEL performance. Its QW material is chosen for the required long-wavelength emission whereas its barrier is expected to ensure promising laser performance at room and higher temperatures. The latter is mostly connected with the QW conduction band offset equal in the above active region to as much as 413 meV, which is much larger than those of its possible lattice matched to InP competitors, e.g. 276 meV for the Ga0.47In0.53As barrier and 346 meV for the Ga0.327In0.673As0.71P0.29 one. Our simulation reveals that from among various considered structures, a VCSEL with a 4-?m-diameter tunnel junction and two 6-nm Ga0.15In0.85N0.015As0.985/Al0.138Ga0.332In0.530As QWs exhibits the lowest calculated threshold current of 0.88 mA. Its promising RT CW performance suggests that it may represent a very interesting alternative to GaSb-based VCSELs.

Sarza?a, Robert P.; Piskorski, ?ukasz; Kudrawiec, Robert; Nakwaski, W?odzmierz

2014-06-01

209

Influence of non-radiative recombination on photoluminescence decay time in GaInNAs quantum wells with Ga- and In-rich environments of nitrogen atoms  

NASA Astrophysics Data System (ADS)

The influence of non-radiative recombination on the photoluminescence decay time (?PL) has been studied for GaInNAs/GaAs quantum wells with Ga- and In-rich environments of N atoms. At low temperatures, this influence is suppressed, due to the carrier localization phenomenon, which leads to a spectral dispersion of ?PL. For investigated samples, this dispersion has been found to be in the range of ~0.2-2.0 ns. With the temperature increase, the free exciton emission starts to dominate instead of the localized exciton emission and the dispersion of ?PL disappears. The dynamic of free exciton recombination is strongly influenced by the non-radiative recombination, which varies between samples, due to different concentration of non-radiative centers. The study of influence of non-radiative recombination on ?PL has been performed at 180 K, since this temperature is high enough to eliminate the localized emission and activate non-radiative recombination and low enough to observe excitonic emission without strong contribution of free carrier recombination when the sample is excited with low power. It was observed that, for as-grown samples, the ?PL increases from 0.14 to 0.25 ns with the change in As/III beam equivalent pressure ratio from 3.8 to 12.1 (in this case, it corresponds to the change in nitrogen nearest-neighbor environment from Ga- to In-rich), whereas, after annealing (i.e., also the change from Ga-rich to In-rich environment of N atoms), this time increases 2-4 times, depending on the As/III ratio. It has been concluded that the ?PL is influenced by point defects rather than the nitrogen nearest-neighbor environment, but their concentration is correlated with the type of nitrogen environment.

Kudrawiec, R.; Syperek, M.; Latkowska, M.; Misiewicz, J.; Korpijärvi, V.-M.; Laukkanen, P.; Pakarinen, J.; Dumitrescu, M.; Guina, M.; Pessa, M.

2012-03-01

210

Electric Machines with Non-Radially Mounted Rectangular Permanent Magnets / Elektrisk?s Maš?nas Ar Prizmatiskiem Neradi?li Novietotiem Past?v?gajiem Magn?tiem  

NASA Astrophysics Data System (ADS)

The authors analyze the advantages and disadvantages of brushless synchronous electric machines with radially and non-radially mounted rectangular permanent magnets. The results show that the proposed nonradial mounting of permanent magnets considered in the paper, in several cases (e.g. multi-pole brushless generators with tooth windings of the armature) allows achievement of the following advantages: better technology of manufacturing the electric machine owing to simple packing of the stator winding in the stator open slots, which also increases the copper slot fillfactor; reduction in the mass-and-size of permanent magnets at least twice; significantly lower cost of the electric machine; and, finally, its greater specific power. Darb? tiek analiz?tas priekšroc?bas un tr?kumi sinhron?m bezkontaktu maš?n?m ar radi?li un neradi?li novietotiem prizmatiskiem past?v?gajiem magn?tiem. Par?d?ts, ka vair?kos gad?jumos, piem?ram, daudzpolu bezkontaktu sinhronajos ?eneratoros ar zobu tinumiem, neradi?ls past?v?go magn?tu izvietojums nodrošina vair?kas priekšroc?bas: uzlabojas maš?nas izgatavošanas tehnolo?ija, jo statora atv?rtaj?s riev?s viegl?k novietot tinumus un iesp?jams sasniegt augst?ku rievas aizpild?juma koeficientu; samazin?s past?v?go magn?tu masa un izmaksas; palielin?s maš?nas ?patn?ja jauda.

Levin, N.; Pugachev, V.; Dirba, J.; Lavrinovicha, L.

2013-04-01

211

Physicochemical properties of the modeled structure of astacin metalloprotease moulting enzyme NAS-36 and mapping the druggable allosteric space of Heamonchus contortus, Brugia malayi and Ceanorhabditis elegans via molecular dynamics simulation.  

PubMed

Nematodes represent the second largest phylum in the animal kingdom. It is the most abundant species (500,000) in the planet. It causes chronic, debilitating infections worldwide such as ascariasis, trichuriasis, hookworm, enterobiasis, strongyloidiasis, filariasis and trichinosis, among others. Molecular modeling tools can play an important role in the identification and structural investigation of molecular targets that can act as a vital candidate against filariasis. In this study, sequence analysis of NAS-36 from H. contortus (Heamonchus contortus), B. malayi (Brugia malayi) and C. elegans (Ceanorhabditis elegans) has been performed, in order to identify the conserved residues. Tertiary structure was developed for an insight into the molecular structure of the enzyme. Molecular Dynamics Simulation (MDS) studies have been carried out to analyze the stability and the physical properties of the proposed enzyme models in the H. contortus, B. malayi and C. elegans. Moreover, the drug binding sites have been mapped for inhibiting the function of NAS-36 enzyme. The molecular identity of this protease could eventually demonstrate how ex-sheathment is regulated, as well as provide a potential target of anthelmintics for the prevention of nematode infections. PMID:24402824

Sharma, Om Prakash; Agrawal, Sonali; Kumar, M Suresh

2013-12-01

212

Ecological risk assessment framework -- the NAS perspective  

SciTech Connect

A Workshop on Ecological Risk Assessment was held on February 26--March 1, 1991, at Airlie House, Warrenton, Virginia. In addition to presentation and discussion of the case study papers, the workshop included breakout sessions to discuss conceptual and technical aspects of ecological risk assessment. A general consensus emerged that an ecological version of the 1983 framework is desirable and feasible. The committee concluded that the 1983 human health framework could be expanded to accomodate both human health and ecological risk assessment. For general applicability to ecological assessments, the 1983 scheme requires augmentation to address some of the interfaces between science and management, primarily because of the need to focus on appropriate questions relevant to applicable environmental law and policy under different circumstances. Specifically, the scheme needs modification to address (1) the influence of legal and regulatory considerations on the initial stages of ecological risk assessment and (2) the importance of characterizing ecological risks in terms that are intelligible to risk managers. The committee`s opinion is that these augmentations are as important for human health risk assessment as they are for ecological risk assessment. This paper briefly describes the framework recommended by the Committee and compares it to EPA`s recently-published Framework for Ecological Risk Assessment.

Barnthouse, L.W.

1993-06-01

213

NAS Forums Focus on National Science Topics  

ERIC Educational Resources Information Center

A series of public meetings designed to focus on complex and persistent problems of national importance involving science has been launched. Topics such as drugs, energy, and natural disasters are included. (DF)

Chemical and Engineering News, 1973

1973-01-01

214

TREINAMENTO DA REANIMAÇÃO CARDIOPULMONAR NAS ESCOLAS  

Microsoft Academic Search

The objective of this work is try to explain the importance of laypeople to be trained to be able to identify a cardiorespiratory stopped, considering that the P.C.R. is the biggest cause of death after the 40 years, greater than the total fatal cases of automobile accidents, AIDS, firearms, breast cancer and lung cancer together. When a person suffers a

Roberta Djanary de Almeida; André Luiz Hoffmann; Eunice Kyosen Nakamura

215

Response to Questions on Presentation to NAS  

SciTech Connect

Response to questions on the presentation 'Overview to Chamber and Power Plant Designs for IFE' made at the 1/29-31 meeting of the National Academies Committee on the Prospects for Inertial Confinement Fusion Energy Systems.

Meier, W R

2011-03-17

216

NAS Report Reveals Dangers From SST  

ERIC Educational Resources Information Center

Reported are some harmful effects of supersonic travel on humans and other living organisms. Slight decreases in ozone concentration as a result of emissions from the SST aircrafts reduce absorption of ultraviolet radiation. Effects of this may include skin cancer, distort balance of activity in cells and have a deleterious effect on insects and…

Fowler, Jo Ann V.

1973-01-01

217

Multiband GaNAsP Quaternary Alloys  

SciTech Connect

We have synthesized GaN{sub x}As{sub 1-y}P{sub y} alloys (x {approx} 0.3-1% and y = 0-0.4) using nitrogen N ion implantation into GaAsP epilayers followed by pulsed laser melting and rapid thermal annealing techniques. As predicted by the band anticrossing model, the incorporation of N splits the conduction band (E{sub M}) of the GaAs{sub 1-y}P{sub y} substrate, and strong optical transitions from the valence band to the lower (E{sub -}) and upper (E{sub +}) conduction subbands are observed. The relative strengths of the E{sub -} and E{sub +} transition change as the localized N level E{sub N} emerges from the conduction band forming narrow intermediate band for y > 0.3. The results show that GaN{sub x}As{sub 1-x-y}P{sub y} alloys with y > 0.3 is a three band semiconductor alloy with potential applications for high-efficiency intermediate band solar cells.

Yu, K.M.; Walukiewicz, W.; Ager III, J.W.; Bour, D.; Farshchi,R.; Dubon, O.D.; Li, S.X.; Sharp, I.D.; Haller, E.E.

2005-12-08

218

F/NAS/ Pressure Temperature Retrieval Techniques  

NASA Technical Reports Server (NTRS)

The purpose of this investigation is to study methods and ways for rapid inversion programs involving the correlated k-method, and to modify the existing programs so that the rapid analysis of data can be accomplished. This short paper presents the background regarding the research as well as accomplishments made during the contract period.

Poularikas, Alexander

1995-01-01

219

Strategic Plans for the Future of Solar Physics: a community discussion of the NASA Sun-Earth Connection Program Roadmap and the NAS Decadal Survey of Astronomy and Astrophysics (Solar Astronomy section)  

NASA Astrophysics Data System (ADS)

The NASA Sun-Earth Connections Program is currently revising its Roadmap, the long-range plan for science goals, technology development, and missions between 2000 and 2040. From the interior dynamics of the Sun, to the interactions of plasma, fields, and radiation in the photosphere and solar atmosphere, to the heating and structure of the corona, to the acceleration, structure, and evolution of the solar wind, to the interactions of the heliosphere with the interstellar medium, to the processes of solar, stellar, and solar system evolution - progress in each of these domains will help us understand how the Sun impacts our home in space. The Roadmap Committee is seeking to refine and extend the SEC's vision and identify the milestone missions for the future. During this session, an outline of the current draft Roadmap will be presented, and further community involvement will be solicited to ensure the strongest possible concensus on the revised Roadmap. The National Academy of Sciences' Space Science Board has appointed a committee to perform a Decadal Survey of Astronomy and Astrophysics, which is surveying the field of space- and ground-based astronomy and astrophysics, recommending priorities for the most important new initiatives of the decade 2000-2010. The prioritization delivered by the earlier Decadal Surveys has played an important role in guiding the funding agencies in setting their priorities for astronomy and astrophysics. Therefore it will be of crucial importance for solar physics to contribute a strong case for its own set of future projects to be incorpoprated into the survey. The solar physics of the next decade will be characterized by its increasing societal relevance in the context of the National Space Weather Program and related issues, as well as its classical importance as a ``base" for many astrophysical questions. The presentation and subsequent discussion at the Chicago meeting is intended to solicit further community input, to achieve optimal representation for solar physics in the Decadal Survey. The Roadmap Committee and the Decadal Survey's solar panel encourage the whole solar physics community to contact them prior to the meeting. The list of the committee/panel members and their e-mail addresses, as well as related information, can be accessed via their websites at http://www.lmsal.com/sec/ and http://www.nas.edu/bpa/projects/astrosurvey/solar/ , respectively.

Schrijver, K.; Knoelker, M.

1999-05-01

220

Job Management Requirements for NAS Parallel Systems and Clusters  

NASA Technical Reports Server (NTRS)

A job management system is a critical component of a production supercomputing environment, permitting oversubscribed resources to be shared fairly and efficiently. Job management systems that were originally designed for traditional vector supercomputers are not appropriate for the distributed-memory parallel supercomputers that are becoming increasingly important in the high performance computing industry. Newer job management systems offer new functionality but do not solve fundamental problems. We address some of the main issues in resource allocation and job scheduling we have encountered on two parallel computers - a 160-node IBM SP2 and a cluster of 20 high performance workstations located at the Numerical Aerodynamic Simulation facility. We describe the requirements for resource allocation and job management that are necessary to provide a production supercomputing environment on these machines, prioritizing according to difficulty and importance, and advocating a return to fundamental issues.

Saphir, William; Tanner, Leigh Ann; Traversat, Bernard

1995-01-01

221

O Conceito de Resiliência Aplicado ao Trabalho nas Organizações  

Microsoft Academic Search

Resilience is a concept that has been used to explain psychosocial phenomena referred to individuals, groups or organizations that surpass or transcend adverse situations. In this study, the use of the concept of resilience as a theoretical referential in the field of Psychology of Work is discussed through: a) content analysis of two recent films - Frida and Life is

Lisete Barlach; Ana Cristina Limongi-França; Sigmar Malvezzi

2008-01-01

222

Implementation of NAS Parallel Benchmarks in High Performance Fortran  

Microsoft Academic Search

We present an HPF implementation of BT, SP, LU, FT, CG and MG of the NPB2.3-serial benchmark set. The implementation is based on HPF perfor- mance model of the benchmark specific primitive operations with distributed arrays. We present pro- filing and performance data on SGI Origin 2000 and compare the results with NPB2.3. We discuss advantages and limitations of HPF

Michael Frumkin; Haoqiang Jin; Jerry Yan

2000-01-01

223

Analysis of Control and Traffic in Operational NAS Environment.  

National Technical Information Service (NTIS)

Work was completed on determination of the applicability of the model to sector staffing, and simulation of control-load and airspace theory. The report summarizes the contractor's views of the model and related problems. It is based on thorough familiari...

N. Amin C. E. Mayfield

1967-01-01

224

Feasibility study for a secondary Na/S battery  

NASA Technical Reports Server (NTRS)

The feasibility of a moderate temperature Na battery was studied. This battery is to operate at a temperature in the range of 100-150 C. Two kinds of cathode were investigated: (1) a soluble S cathode consisting of a solution of Na2Sn in an organic solvent and (2) an insoluble S cathode consisting of a transition metal dichalcogenide in contact with a Na(+)ion conducting electrolyte. Four amide solvents, dimethyl acetamide, diethyl acetamide, N-methyl acetamide and acetamide, were investigated as possible solvents for the soluble S cathode. Results of stability and electrochemical studies using these solvents are presented. The dialkyl substituted amides were found to be superior. Although the alcohol 1,3-cyclohexanediol was found to be stable in the presence of Na2Sn at 130 C, its Na2Sn solutions did not appear to have suitable electrochemical properties.

Abraham, K. M.; Schiff, R.; Brummer, S. B.

1979-01-01

225

Correlation of DLTS and Performance of GalnNAs Cells.  

National Technical Information Service (NTIS)

A four-junction GaInP/GaAs/GaInAsN/Ge solar cell should be able to reach 40% efficiency if each of the junctions can be made with a quality similar to that demonstrated for GaAs. However, the GaInAsN subcell has shown poor performance. Deep-level transien...

S. Kurtz S. Johnston D. Friedman A. Ptak J. Geisz W. McMahon

2005-01-01

226

NAS Algorithm for Semantic Query Routing Systems in Complex Networks  

Microsoft Academic Search

The modern distributed systems are acquiring a great importance in our daily lives. Each day more transactions are conducted\\u000a through devices which perform queries that are dependent on the reliability, availability and security of distributed applications.\\u000a In addition, those systems show great dynamism as a result of the extremely complex and unpredictable interactions between\\u000a the distributed components, making it practically

Laura Cruz Reyes; Claudia Guadalupe Gómez Santillán; Marco Antonio Aguirre Lam; Satu Elisa Schaeffer; Tania Turrubiates López; Rogelio Ortega Izaguirre; Héctor Joaquin Fraire Huacuja

2008-01-01

227

Transforming the NAS: The Next Generation Air Traffic Control System  

NASA Technical Reports Server (NTRS)

The next-generation air traffic control system must be designed to safely and efficiently accommodate the large growth of traffic expected in the near future. It should be sufficiently scalable to contend with the factor of 2 or more increase in demand expected by the year 2020. Analysis has shown that the current method of controlling air traffic cannot be scaled up to provide such levels of capacity. Therefore, to achieve a large increase in capacity while also giving pilots increased freedom to optimize their flight trajectories requires a fundamental change in the way air traffic is controlled. The key to achieving a factor of 2 or more increase in airspace capacity is to automate separation monitoring and control and to use an air-ground data link to send trajectories and clearances directly between ground-based and airborne systems. In addition to increasing capacity and offering greater flexibility in the selection of trajectories, this approach also has the potential to increase safety by reducing controller and pilot errors that occur in routine monitoring and voice communication tasks.

Erzberger, Heinz

2004-01-01

228

Impact of National Airspace Systems (NAS) Modernization on Aircraft Emissions.  

National Technical Information Service (NTIS)

Government and industry agree that a reduction in air traffic control restriction has an enormous potential for time and resource savings. This consensus is well documented in RTCA task force reports and in the National Civil Aviation Review Commission Re...

1998-01-01

229

Bush climate research plans draw mixed reaction From NAS panel  

Microsoft Academic Search

The Bush administration provided a guarded progress report on the development of its new climate change research initiatives during a November 19 meeting of the National Academy of Sciences' Committee on Global Change Research. Some committee members, however, criticized the plans as short on specifics and substance.Administration officials told the committee that two initiatives announced by President George W. Bush

Randy Showstack

2001-01-01

230

Science and Decisions: Advancing Risk Assessment (NAS Final Report)  

EPA Science Inventory

In August 2009, the Committee on Improving Risk Analysis Approaches Used by the U.S. EPA, National Research Council released a final report, requested and sponsored by the EPA, entitled Science and Decisions: Advancing Risk Assessment 2009....

231

NAS Associate Works on Environmental Implications of Nanoparticles  

EPA Science Inventory

Dr. Manomita Patra joined the EPA's, Human Exposure and Atmospheric Sciences Division at the Las Vegas, NV location in June 2007. Her research project parallels her previous interests in the genotoxicity of mercury in plants. She is working with Dr. Kim Rogers and Tammy Jones-Lep...

232

PM HAZARDOUS COMPONENTS, MECHANISMS, & DOSIMETRY (NAS 5,6, & 9)  

EPA Science Inventory

The goals of this research are to evaluate the physical and chemical characteristics of fine PM from combustion sources and, most importantly, to understand the characteristics and formation mechanisms which influence particle toxicity. EPA will determine how chemical and physi...

233

PM - EMISSION CHARACTERIZATION, FACTORS AND CONTROLS (NAS 12)  

EPA Science Inventory

The program will focus on diesel trucks, prescribed and open burning, construction sites and residential wood combustion. Differences in emission rates due to changes in operating conditions and fuel type will be included in the revised factors. Ammonia research will produce i...

234

Exploración de la validez de constructo de la escala de Zung para depresión en adolescentes escolarizados  

Microsoft Academic Search

SUMMARY Background: The Zungs self-rating depression scale has been used in various Colombian studies among adolescents. However, its construct validation has not been yet reported. Objective: To validate the construct of the Zungs self-rating depression scale in adolescent attending a low income public school at the city of Cartagena, Colombia. Method: A total of 408 students aged 13-17 years old

ZULEIMA C OGOLLO; CARMEN E LENA; ADALBERTO C AMPO

2006-01-01

235

Evaluación de Insatisfacción Corporal en adolescentes: Efecto de la forma de administración de una escala  

Microsoft Academic Search

Title: Assessment of Body Dissatisfaction in adolescents: effect of the way of administration a scale. Abstract: The aim of this paper is to discover if the way of administration a subscale of evaluation Body Dissatisfac- tion (BD), coming from a wider questionnaire, affects to the tendency of answer. In the investigation participated 147 students of sec- ondary school, age between

José Ignacio Baile; Rosa María Raich; Emilio Garrido; Ayuntamiento de Pamplona

2003-01-01

236

Astronomia Motivadora no Ensino Fundamental  

NASA Astrophysics Data System (ADS)

O objetivo principal deste trabalho é procurar desenvolver o interesse dos alunos pelas ciências através da Astronomia. Uma pesquisa com perguntas sobre Astronomia foi realizada junto a 161 alunos do Ensino Fundamental, com o intuito de descobrir conhecimentos prévios dos alunos sobre o assunto. Constatou-se, por exemplo, que 29,3% da 6ª série responderam corretamente o que é eclipse, 30,0% da 8ª série acertaram o que a Astronomia estuda, enquanto 42,3% dos alunos da 5ª série souberam definir o Sol. Pretende-se ampliar as turmas participantes e trabalhar, principalmente de forma prática com: dimensões e escalas no Sistema Solar, construção de luneta, questões como dia e noite, estações do ano e eclipses. Busca-se abordar, também, outros conteúdos de Física tais como a óptica na construção da luneta, e a mecânica no trabalho com escalas e medidas, e ao utilizar uma luminária para representar o Sol na questão do eclipse, e de outras disciplinas como a Matemática na transformação de unidades, regras de três; Artes na modelagem ou desenho dos planetas; a própria História com relação à busca pela origem do universo, e a Informática que possibilita a busca mais rápida por informações, além de permitir simulações e visualizações de imagens importantes. Acredita-se que a Astronomia é importante no processo ensino aprendizagem, pois permite a discussão de temas curiosos como, por exemplo, a origem do universo, viagens espaciais a existência ou não de vida em outros planetas, além de temas atuais como as novas tecnologias.

Melo, J.; Voelzke, M. R.

2008-09-01

237

Protótipo do primeiro interferômetro brasileiro - BDA  

NASA Astrophysics Data System (ADS)

A interferometria é uma poderosa ferramenta usada para investigar estruturas espaciais de fontes astrofísicas fornecendo uma riqueza de detalhes inatingível pelas técnicas convencionais de imageamento. Em particular, a interferometria com ondas de rádio abre o horizonte de conhecimento do Universo nesta ampla banda do espectro eletromagnético, que vai de cerca de 20 kHz até centenas de GHz já próximo ao infravermelho, e que está acessível a partir de instrumentos instalados em solo. Neste trabalho, apresentamos o interferômetro designado por Arranjo Decimétrico Brasileiro (BDA). Trata-se do primeiro interferômetro a ser desenvolvido no Brasil e América Latina que já está em operação na fase de protótipo. Apresentamos o desenvolvimento realizado até o momento, o sítio de instalação do instrumento, o protótipo e os principais resultados dos testes de sua operação, as perspectivas futuras e a ciência a ser desenvolvida com o instrumento nas fases II e III. Neste trabalho é dada ênfase ao desenvolvimento, testes de operação e principais resultados do protótipo. É discutida brevemente a ciência que pode ser feita com o instrumento. Tanto os detalhes técnicos quanto os principais parâmetros estimados para o instrumento nas próximas fases de desenvolvimento e o desempenho do protótipo serão publicados em breve.

Cecatto, J. R.; Fernandes, F. C. R.; Neri, J. A. C. F.; Bethi, N.; Felipini, N. S.; Madsen, F. R. H.; Andrade, M. C.; Soares, A. C.; Alonso, E. M. B., Sawant, H. S.

2004-04-01

238

Aplicación de la Escala de Depresión del Center of Epidemiological Studies en adolescentes de la Ciudad de México  

Microsoft Academic Search

Objective. To assess the internal consistency, as well as the construct, concurrent and external consistency of the Center for Epidemiologic Studies Depression Scale (CES- D-R) in Mexican adolescents. Material and Methods. The data are from two samples of middle-school students from Mexico City. The questionnaire included the CES-D-R and other scales for suicide problems, peer and family violence, and drug

Catalina González-Forteza; José Alberto Jiménez-Tapia; Luciana Ramos-Lira; Fernando A Wagner

2008-01-01

239

Relaciones de pareja y juego patológico: un estudio descriptivo a través de la Escala de Ajuste Diádico (DAS)  

Microsoft Academic Search

Pathological gambling is a psychological disturbance known to affect gravely the gambler's family environment and, specifically, his\\/her spousal relationship. The article shows the result of a study relating diverse sociodemographic variables to spousal relationships assessed according to Spaniers Dyadic Adjustment Scale (DAS). The results demonstrate a lesser dyadic adjustment for marriages with a pathological gambler. Likewise, certain variables such as

Miguel GARRIDO FERNÁNDEZ; Pedro JAÉN RINCÓN; DOMÍNGUEZ ÁLVAREZ; ASEJER Sevilla

240

[Adaptation and psychometric proprieties study for the portuguese version of the adolescent coping scale - escala de coping para adolescentes].  

PubMed

Introduction: Coping is a psychological process that prompts the individual to adapt to stressful situations. The Adolescent Coping Scale is a widely used research and clinical tool. This study aimed to develop a Portuguese version of the Adolescent Coping Scale and to analyze the strategies and coping styles of young people in our sample. Material and Methods: An anonymous questionnaire comprising the Adolescent Coping Scale was submitted and replied by 1 713 students (56% female, from 12 to 20 years, average age 16) The validity study of the scale included: principal component and reliability analysis; confirmatory analysis using structural equation modelling Subsequently, a gender comparison of both the strategies and the coping styles was conducted through independent samples t tests. Results: The final structure of the Adolescent Coping Scale adaptation retained 70 items assessing 16 coping strategies grouped into three major styles. The scales showed good internal consistency (Cronbach alpha values between 0.63. and 0.86, with the exception of one dimension that as shown a value of 0.55) and the confirmatory model showed a good fit (goodness of fit index values between 0.94 e 0.96). Two coping strategies were eliminated on statistical grounds (insufficient saturations of items in the corresponding dimensions). We found that the style of coping focused on problem solving is the most used by youths from our sample, in both sexes. Females had higher mean values in non-productive coping style and reference to others. Discussion: This adapted version has high similarity with the original scale, with expectable minor changes, given that coping is influenced by cultural, geographical and socio-economic variables. Conclusion: The present study represents an important part of the validation protocol Portuguese Adolescent Coping Scale, including its linguistic adaptation and its internal consistency and factor structure studies. PMID:24813484

Guerreiro, Diogo Frasquilho; Cruz, Diana; Figueira, Maria Luísa; Sampaio, Daniel

2014-01-01

241

Low threshold current continuous-wave GaInNAs\\/GaAs VCSELs  

Microsoft Academic Search

Vertical cavity surface-emitting lasers (VCSELs) emitting near 0.85 ?m are becoming increasingly important for short-haul optical fiber transmission systems. These devices benefit from highly reflective and thermally conductive all-epitaxial GaAs-based mirrors and efficient transverse confinement through AlAs-oxide dielectric apertures. Extending this commercially-established technology to wavelengths in the 1.3-1.6 ?m range allows for dramatically increased transmission bandwidth and distance in conventional

M. C. Larson; C. W. Coldren; S. G. Spruytte; H. E. Petersen; J. S. Harris

2000-01-01

242

Comparison of Origin 2000 and Origin 3000 Using NAS Parallel Benchmarks.  

National Technical Information Service (NTIS)

This report describes results of benchmark tests on the Origin 3000 system currently being installed at the NASA Ames National Advanced Supercomputing facility. This machine will ultimately contain 1024 R14K processors. The first part of the system, insta...

R. D. Turney

2001-01-01

243

Ceramics technical activities, 1993 (NAS-NRC assessment panel April 21-22, 1994)  

SciTech Connect

In 1993 the Ceramics Division continued to emphasize a technical program directly relevant to the needs of U.S. industry. The program is made up of tasks which involve standard materials development, construction of evaluated databases, and laboratory research focused on topics that address the dominant issues affecting commercialization of advanced ceramics, namely, processing costs and reliability. In accord with the strategic plan laid out by the Materials Science and Engineering Laboratory, the Ceramics Division is continuing to expand its direct involvement with industrially related research issues. Standard materials and data activities continue to represent an important portion of the Division's program. Three new Standard Reference Materials were developed this year, and an evaluated database on high Tc superconducting materials was begun in collaboration with a Japanese laboratory.

Not Available

1994-01-01

244

Performance of Sodium-beta Alumina Solid Electrolyte in Na/S Cells.  

National Technical Information Service (NTIS)

The performance of sodium-beta alumina type solid electrolytes is limited by degradation. Two different modes of degradation are discussed. Mode I involves the well studied current focusing on a pre-existing surface flaw; Mode II involves internal sodium ...

L. C. De Jonghe

1981-01-01

245

Valor preditivo da dor à compressão do globo ocular nas síndromes meníngeas  

Microsoft Academic Search

Meningeal syndromes are evaluated in clinical practice by classic semiological signs all of them showing important sensibility and specificity but with some limitations. Thus, we propose a clinical method in order to diagnose meningeal syndromes capable of being easily executed and without risks for patients: to evaluate the pain by ocular globe compression as a semiological sign in meningeal syndromes.

Luciano Holanda; Gabrielle Nascimento de Holanda; José Tavares-Neto

2002-01-01

246

Post-test analyses of Na/S cells and aqueous batteries  

NASA Astrophysics Data System (ADS)

Post-test examinations are conducted at Argonne National Laboratory to obtain quantitative information on electrode morphology, corrosion and degradation of the cell hardware, and mechanisms responsible for existing or future cell failures. These findings are reported to the organizations responsible for the construction of these cells and support their efforts in achieving improved cell performance, cycle life, and reliability. Results of post-test analyses of recent high-temperature sodium/sulfur cells, and of aqueous lead-acid and nickel/iron batteries are presented. In particular, the relationship between electrode performance and electrode morphology is examined for each of the three battery systems.

Battles, J. E.; Smaga, J. A.; Marr, J. J.

247

Development of GaInNAs-based 1.3-?m VCSEL  

NASA Astrophysics Data System (ADS)

In this paper the realization, development and production of 1.3?m vertical cavity surface emitting lasers (VCSEL) with datacom suitable performance are presented. These low cost laser diodes are well suited for optical interconnect applications for LAN and MAN with transmission distances up to 15 km. The possibilities as well as the advantages and limits of shifting the wavelength from commercially available VCSEL emitting at 850nm to 1300nm are discussed. 1300nm VCSELs in a low cost SMD plastic package assembled into an intelligent SFP-module developed by Infineon Technologies are demonstrated.

Ramakrishnan, Arun; Ebbinghaus, G.; Lima, A.; Supper, D.; Kristen, Guenter; Popp, M.; Degen, C.; Althaus, H.-L.; Killer, T.; Scholz, R.; Melinde, M.; Sauter, M.; Weigert, M.; Riechert, Henning; Steinle, Gunther

2003-12-01

248

INFLUÊNCIA DA VELOCIDADE DE CARBONIZAÇÃO DA MADEIRA NOS RENDIMENTOS E NAS PROPRIEDADES DO CARVÃO PRODUZIDO  

Microsoft Academic Search

Wood of Ecalyptus tereticornis was carbonized in an eletric heated, laboratory size, and retort. Proposed heating velocities were 0.42; 0.63; 0.84; 1.05 and 1.26°C\\/min. Maximum temperature was 450°C. True heating velocities were estimated at the end of each carbonization using the measured temperatures. Regression analysis were used to evaluate the effect of the proposed and tree heating velocity on the

MERCEDES MARÍLIA; C. F. VELLA; OSVALDO FERREIRA VALENTE; BENEDITO ROCHA; VITAL JOSÉ; GABRIEL DE LELLES

1989-01-01

249

HPF and MPI Implementation of the NAS Parallel Benchmarks Supported by Integrated Program Engineering Tools  

Microsoft Academic Search

High Performance Fortran (HPF) compilers and communication libraries with the standardized Mes- sage Passing Interface (MPI) are becoming widely avail- able, easing the development of portable parallel appli- cations on distributed-memory parallel processor systems . The recently developed Annai tool environment supports programming, debugging and tuning of both HPF- and MPI-based applications. Considering code development and subsequent maintenance time to

Christian Cl; Karsten M. Decker; Vaibhav R. Deshpande; Akiyoshi Endo; Josef Fritscher; Paulo A. R. Lorenzo; Norio Masuda; William Sawyer; Brian J. N. Wylie; Frank Zimmermann

250

Tools-supported HPF and MPI parallelization of the NAS parallel benchmarks  

Microsoft Academic Search

High Performance Fortran (HPF) compilers and communication libraries with the standardized Message Passing Interface (MPI) are becoming widely available, easing the development of portable parallel applications. The Annai tool environment supports programming, debugging and tuning of both HPF- and MPI-based applications. Considering code development time to be as important as final performance, we address how sequential versions of the familiar

C. Clemencon; Karsten M. Decker; Vaibhav R. Deshpande; Akiyoshi Endo; Josef Fritscher; Paulo A. R. Lorenzo; Norio Masuda; Andreas Muller; R. Ruhl; W. Sawyer; B. J. N. Wylie; F. Zimmermann

1996-01-01

251

NOTIFICAÇÕES TÉCNICAS E FITOSSANITÁRIAS À OMC: QUAL O IMPACTO NAS EXPORTAÇÕES AGRÍCOLAS DO BRASIL?  

Microsoft Academic Search

É notória a crescente importância das medidas técnicas, sanitárias e fitossanitárias às exportações brasileiras de produtos agrícolas, tais como: certificação de origem, avaliação de conformidade, normas e procedimentos técnicos, etc. Essas medidas têm sido formalizadas em notificações aos acordos TBT e SPS da OMC, vigentes desde 1995. Cabe ressaltar, no entanto, que essas medidas podem servir como barreiras protecionistas quando

Braulio Martins Bueno; Orlando Monteiro da Silva

2008-01-01

252

Preliminary C3 Loading Analysis for Future High-Altitude Unmanned Aircraft in the NAS  

NASA Technical Reports Server (NTRS)

This document provides a preliminary assessment and summary of the command, control, and communications (C(sup 3)) loading requirements of a generic future high-altitude, long-endurance unmanned aircraft (UA) operating at in the National Airspace System. Two principal types of C(sup 3) traffic are considered in our analysis: communications links providing air traffic services (ATS) to the UA and its human pilot, and the command and control data links enabling the pilot to operate the UA remotely. we have quantified the loading requirements of both types of traffic for two different assumed levels of UA autonomy. Our results indicate that the potential use of UA-borne relays for the ATS links, and the degree of autonomy exercised by the UA during the departure and arrival phases of its flight, will be among the key drivers of C(sup 3) loading and bandwidth requirements.

Ho, Yan-Shek; Gheorghisor, Izabela; Box, Frank

2006-01-01

253

Polymers: Technical activities, 1991. NAS-NRC Assessment Panel, February 13-14, 1992  

SciTech Connect

All of the Division's programs are described in the report, organized according to these six Groups. These Groups have made a number of significant accomplishments during the last year. Some of these are summarized below: A computer simulation was performed to model resin flow in liquid molding of the front end structure of a Ford Escort; A NIST/industry consortium has evolved for the purpose of developing in-line measurement technology based on optical and fluorescence methods; A combined light scattering photometer/rheometer has been constructed to examine phase separation behavior of polymer blends and solutions under the influence of a simple shear field; A unique new tool has been developed to study the physics involved in the adhesion between a polymer and a solid surface like glass; The distribution of polarization in poly(vinylidene fluoride) poled by corona discharge rather than by contacting electrodes indicated positive charge injection near the surface; Proton spin diffusion results indicated domain sizes in poly(butylmethacrylate)/hydroxy modified polystyrene blends with minimum dimensions in the 6-10 nm range and stoichiometries of the order of 75/25; Novel, siloxane-containing difunctional and multifunctional vinyl monomers were prepared; The apparent 'shift' in polymer blend phase separation temperature, Tc, under shear flow has been interpreted with the mode-coupling theory for mean-field polymer blend systems; The radial flow behavior was successfully predicted from measurements in unidirectional flow; An exposure technique that rapidly determines whether or not a polymer is biodegradable has been developed; Instrumentation has been set up and calibrated to measure the dielectric constant of thin polymer films at high electric fields; A viscoelastic model of stresses in porcelain-metal strips has been developed.

Smith, L.E.; Fanconi, B.M.

1991-10-01

254

Testing of an Acrylic Evaporator to Aid Understanding of NAS Deposition  

SciTech Connect

As part of the 2H evaporator scaling investigation, a decision was made to construct a small, nominally 5 gallon unit to determine if sufficient data could be obtained at this scale and be representative of the plant system.

Herman, D.

2002-12-18

255

Morphological breakdown during growth of a high nitrogen content GaInNAs thin film  

NASA Astrophysics Data System (ADS)

The breakdown in surface morphology during the growth of an 8 nm thick Ga 0.7In 0.3N 0.05As 0.95 layer has been investigated by scanning tunnelling microscopy. During initial growth (<0.5 nm) the alloy layer is planar but strained. Lateral composition modulation due to spinodal decomposition leads to the co-existence of tensile strained N-rich regions and compressively strained N-poor regions, creating an oscillatory strain field (OSF) across the surface. The overall strain increases with layer thickness up to ˜0.5 nm, after which it is relieved by a transition from two-(2D) to three-dimensional (3D) growth, which manifests itself as an undulating, pitted layer. We propose that the region at the bottom of each pit is N-rich and that overgrowth of such regions is inhibited, thereby avoiding the strain caused by lattice mismatch. The results offer insight into the mechanisms involved in the breakdown of the 2D growth of thin dilute nitride layers at relatively high N concentrations.

McGee, W. M.; Williams, R. S.; Ashwin, M. J.; Jones, T. S.

2006-08-01

256

Support of Activities of the NAS in Relation to the Radiation Effects Research Foundation  

SciTech Connect

The National Academies (NA) provides support for the activities related to the long-term follow up of the health of the survivors of the atomic bombings of Hiroshima and Nagasaki being conducted by the Radiation Effects Research Foundation (RERF) laboratories in Hiroshima and Nagasaki, Japan. The NA serves as scientific and administrative liaison between the U.S. Department of Energy (DOE) and RERF, and performs tasks in the areas of scientific oversight, information/public interface, fiscal oversight, and personnel management. The project includes recruitment and support of approximately 10 NA employees who work at RERF in Japan. Specific activities are performed consistent with the cooperative agreement’s Statement of Work between DOE and NA and consistent with an Annual Work Plan developed by DOE and NA.

Douple, Evan B.

2006-05-31

257

48 CFR 852.236-83 - Payments under fixed-price construction contracts (including NAS).  

Code of Federal Regulations, 2010 CFR

...in each activity cost of the critical path method (CPM) network. (4) The CPM network shall include a separate cost loaded activity...contractor shall show on the critical path method (CPM) network the total cost of the guarantee...

2010-10-01

258

48 CFR 852.236-83 - Payments under fixed-price construction contracts (including NAS).  

Code of Federal Regulations, 2010 CFR

...in each activity cost of the critical path method (CPM) network. (4) The CPM network shall include a separate cost loaded activity...contractor shall show on the critical path method (CPM) network the total cost of the guarantee...

2009-10-01

259

Nearest-neighbor configuration in (GaIn)(NAs) probed by x-ray absorption spectroscopy.  

PubMed

Ga(1-x)In(x)N(y)As(1-y) is a promising material system for the fabrication of inexpensive "last-mile" optoelectronic components. However, details of its atomic arrangement and the relationship to observed optical properties is not fully known. Particularly, a blueshift of emission wavelength is observed after annealing. In this work, we use x-ray absorption fine structure to study the chemical environment around N atoms in the material before and after annealing. We find that as-grown molecular beam epitaxy material consists of a nearly random distribution of atoms, while postannealed material shows segregation of In toward N. Ab initio simulations show that this short-range ordering creates a more thermodynamically stable alloy and is responsible for blueshifting the emission. PMID:12731929

Lordi, Vincenzo; Gambin, Vincent; Friedrich, Stephan; Funk, Tobias; Takizawa, Toshiyuki; Uno, Kazuyuki; Harris, James S

2003-04-11

260

GASTO CALÓRICO NAS ATIVIDADES DE TRABALHO E COTIDIANAS, DOS CARTEIROS QUE UTILIZAM BICICLETA  

Microsoft Academic Search

The study aimed to identify lifestyle behaviors and to quantify caloric expenditure in daily and labor activities of bike postmen (employees from CORREIOS - Brazilian Postal Services) of the city of São José - SC - Brazil. The methodology used an interview using the IPAQ questionnaire, anthropometric measurements and records of daily activities (measuring time spent in selecting mail, and

Eduardo Barbosa Almeida; Giselle Noceti; Ammon Xavier; Lorival José Carminatti; Milton Carlos; Della Giustina

2004-01-01

261

Large UAS Operations in the NAS - The NASA 2007 Western States Fire Missions (WSFM)  

NASA Technical Reports Server (NTRS)

Objectives: Demonstrate capabilities of UAS to overfly and collect sensor data on wildfires throughout Western US. Demonstrate long-endurance mission capabilities (20+ hours). Image multiple fires (greater than 4 fires per mission), to showcase extendable mission configuration and ability to either linger over key fires or station over disparate regional fires. Deliver real-time imagery to (within 10-minutes of acquisition).

Buoni, Gregory P.; Howell, Kathleen M.

2008-01-01

262

A Validation Study of Merging and Spacing Techniques in a NAS-Wide Simulation  

NASA Technical Reports Server (NTRS)

In November 2010, Intelligent Automation, Inc. (IAI) delivered an M&S software tool to that allows system level studies of the complex terminal airspace with the ACES simulation. The software was evaluated against current day arrivals in the Atlanta TRACON using Atlanta's Hartsfield-Jackson International Airport (KATL) arrival schedules. Results of this validation effort are presented describing data sets, traffic flow assumptions and techniques, and arrival rate comparisons between reported landings at Atlanta versus simulated arrivals using the same traffic sets in ACES equipped with M&S. Initial results showed the simulated system capacity to be significantly below arrival capacity seen at KATL. Data was gathered for Atlanta using commercial airport and flight tracking websites (like FlightAware.com), and analyzed to insure compatible techniques were used for result reporting and comparison. TFM operators for Atlanta were consulted for tuning final simulation parameters and for guidance in flow management techniques during high volume operations. Using these modified parameters and incorporating TFM guidance for efficiencies in flowing aircraft, arrival capacity for KATL was matched for the simulation. Following this validation effort, a sensitivity study was conducted to measure the impact of variations in system parameters on the Atlanta airport arrival capacity.

Glaab, Patricia C.

2011-01-01

263

Evaluation of the Terminal Precision Scheduling and Spacing System for Near-Term NAS Application  

NASA Technical Reports Server (NTRS)

NASA has developed a capability for terminal area precision scheduling and spacing (TAPSS) to provide higher capacity and more efficiently manage arrivals during peak demand periods. This advanced technology is NASA's vision for the NextGen terminal metering capability. A set of human-in-the-loop experiments was conducted to evaluate the performance of the TAPSS system for near-term implementation. The experiments evaluated the TAPSS system under the current terminal routing infrastructure to validate operational feasibility. A second goal of the study was to measure the benefit of the Center and TRACON advisory tools to help prioritize the requirements for controller radar display enhancements. Simulation results indicate that using the TAPSS system provides benefits under current operations, supporting a 10% increase in airport throughput. Enhancements to Center decision support tools had limited impact on improving the efficiency of terminal operations, but did provide more fuel-efficient advisories to achieve scheduling conformance within 20 seconds. The TRACON controller decision support tools were found to provide the most benefit, by improving the precision in schedule conformance to within 20 seconds, reducing the number of arrivals having lateral path deviations by 50% and lowering subjective controller workload. Overall, the TAPSS system was found to successfully develop an achievable terminal arrival metering plan that was sustainable under heavy traffic demand levels and reduce the complexity of terminal operations when coupled with the use of the terminal controller advisory tools.

Thipphavong, Jane; Martin, Lynne Hazel; Swenson, Harry N.; Lin, Paul; Nguyen, Jimmy

2012-01-01

264

Estados eletronicos superexcitados nas moleculas de etileno e acetileno. (Superexcited states on ethylene and acetylene).  

National Technical Information Service (NTIS)

Electron energy loss spectra were obtained for C(sub 2)H(sub 2) and C(sub 2)H(sub 4) in the energy loss range from 12 to 50 eV for 1 Kev electrons. Elastic and inelastic cross sections and generalized oscillator strengths for transitions at 13.3, 15.7 and...

A. C. Azevedo e Souza G. G. B. Souza

1988-01-01

265

Characteristics of InAs/GaNAs strain-compensated quantum dot solar cell  

NASA Astrophysics Data System (ADS)

We have fabricated and compared the performance of GaAs-based p-i-n quantum dot solar cells with ten multilayer stacked structures of self-assembled InAs quantum dots embedded with GaNxAs1-x strain-compensating spacer layers. Reducing the thickness of the spacer layer, and hence increasing the nitrogen composition in GaNxAs1-x, from 40 nm (x=0.5%) to 15 nm (x=1.5%) thereby fulfilling the net strain-balanced condition, resulted in a steady increase in the short-circuit density, while a decreasing trend for the open-circuit voltage was observed. The observed results can be interpreted in terms of the difference in the quantum confinement structure.

Okada, Yoshitaka; Oshima, Ryuji; Takata, Ayami

2009-07-01

266

48 CFR 852.236-83 - Payments under fixed-price construction contracts (including NAS).  

Code of Federal Regulations, 2013 CFR

...tube system 10 Incinerators (medical waste and trash) 5 Sewage treatment plant equipment 5 Water treatment plant equipment 5 Washers (dish, cage...600 Sections) 5 Entire boiler plant system (Specified under 700...

2013-10-01

267

48 CFR 852.236-82 - Payments under fixed-price construction contracts (without NAS).  

Code of Federal Regulations, 2013 CFR

...Tube System 10 Incinerators (medical waste and trash) 5 Sewage treatment plant equipment 5 Water treatment plant equipment 5 Washers (dish, cage...600 Sections) 5 Entire boiler plant system (Specified under 700...

2013-10-01

268

Gordon and Mike's ICT Podcast: NSF, NAS, etc and the SMET Pipeline  

NSDL National Science Digital Library

Gordon and Mike's ICT Podcast offers perspectives on the information and communication technologies (ICT) industries from Gordon Snyder and Mike Qaissaunee. In this podcast, Mike and Gordon discuss "Science, Math, Engineering and Technology (SMET) pipeline and work being done by the National Academy of Science and the National Science Foundation." Running time for the show is 16:57.This podcast is available for direct download in mp3 format from the Libsyn site, or click here to subscribe to the whole series in iTunes.

Qaissaunee, Michael; Snyder, Gordon F.

2008-03-13

269

Gestão da Qualidade nas Agroindústrias: Um Estudo Exploratório no Município de Marau-RS  

Microsoft Academic Search

This research had as objective identifies the quali ty eras, proposed by Garvin (2002), in which the agri-food industry of one city of Brazil (Marau-RS) are framed, as well as to identify the actions executed by these companies, i n relation to the quality management, and the quality tools that these use. For that, an exploratory research was accomplished, and

IVO DE MORAES PASCHE; GABRIEL MURAD; BRASILIENSE DE EDUCAÇ ÃO

270

BOREAS TE-9 In Situ Diurnal Gas Exchange of NAS Boreal Forest Stands  

NASA Technical Reports Server (NTRS)

The BOREAS TE-9 team collected several data sets related to chemical and photosynthetic properties of leaves in boreal forest tree species. The purpose of the BOREAS TE-09 study was threefold: 1) to provide in situ gas exchange data that will be used to validate models of photosynthetic responses to light, temperature, and carbon dioxide (CO2); 2) to compare the photosynthetic responses of different tree crown levels (upper and lower); and 3) to characterize the diurnal water potential curves for these sites to get an indication of the extent to which soil moisture supply to leaves might be limiting photosynthesis. The gas exchange data of the BOREAS NSA were collected to characterize diurnal gas exchange and water potential of two canopy levels of five boreal canopy cover types: young jack pine, old jack pine, old aspen, lowland old black spruce, and upland black spruce. These data were collected between 27-May-1994 and 17-Sep-1994. The data are provided in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Margolis, Hank; Coyea, Marie; Dang, Qinglai

2000-01-01

271

Design of Unstructured Adaptive (UA) NAS Parallel Benchmark Featuring Irregular, Dynamic Memory Accesses  

NASA Technical Reports Server (NTRS)

We describe the design of a new method for the measurement of the performance of modern computer systems when solving scientific problems featuring irregular, dynamic memory accesses. The method involves the solution of a stylized heat transfer problem on an unstructured, adaptive grid. A Spectral Element Method (SEM) with an adaptive, nonconforming mesh is selected to discretize the transport equation. The relatively high order of the SEM lowers the fraction of wall clock time spent on inter-processor communication, which eases the load balancing task and allows us to concentrate on the memory accesses. The benchmark is designed to be three-dimensional. Parallelization and load balance issues of a reference implementation will be described in detail in future reports.

Feng, Hui-Yu; VanderWijngaart, Rob; Biswas, Rupak; Biegel, Bryan (Technical Monitor)

2001-01-01

272

Voltage Sag Mitigation using NAS Battery-based Standby Power Supply  

Microsoft Academic Search

Advances in industrial automation and manufacturing systems led to the utilization of advanced systems comprise of computers, adjustable speed drives and various industrial control systems that are sensitive to power quality problem, mainly voltage sags. Voltage sag is the reduction of the voltage at a user position with duration of between one cycle and a few seconds caused by motor

Z. F. Hussien; A. B. Ismail; W. C. Lee; A. M. Busrah; M. F. M. Siam

2005-01-01

273

Production Technology of beta-Alumina Ceramics for Na/S Batteries.  

National Technical Information Service (NTIS)

The development of the fabrication processes to produce tubes of beta-alumina ceramics for the Na/S-battery was made on the basis of the results in 1974 and in close cooperation with the Research Center of BBC in Heidelberg. The selection of raw materials...

G. Heimke G. Willmann

1979-01-01

274

Implementation of BT, SP, LU, and FT of NAS Parallel Benchmarks in Java.  

National Technical Information Service (NTIS)

A number of Java features make it an attractive but a debatable choice for High Performance Computing. We have implemented benchmarks working on single structured grid BT,SP,LU and FT in Java. The performance and scalability of the Java code shows that a ...

M. Schultz M. Frumkin H. Q. Jin J. Yan

2000-01-01

275

Desenvolvimento e simulacao computacional de bombas eletromagneticas termoeletricas para o controle do escoamento em reatores nucleares espaciais refrigerados a metal liquido. (Development and computational simulation of thermoelectric electromagnetic pumps for controlling the fluid flow in liquid metal cooled space nuclear reactors).  

National Technical Information Service (NTIS)

Thermoelectric Electromagnetic (TEEM) Pumps can be used for controlling the fluid flow in the primary and secondary circuits of liquid metal cooled space nuclear reactor. In order to simulate and to evaluate the pumps performance, in steady-state, the com...

E. M. Borges

1991-01-01

276

Observacoes do Cometa de Halley no Continuo de 22 GHz E 44 GHz, E NA Raia Maser de Vapor de H20 EM 22.2 GHz  

NASA Astrophysics Data System (ADS)

0 cometa de Halley foi observado no contínuo nas frequencias de 22 GHz e 44 GHz no Observatório de Itapetinga, Brasil, no período Fevereiro-Abril de 1986. 0 cometa foi detetado em ambas frequ?ncias, apresentando variabilidade corn escalas de tempo de horas. Cálculos teóricos mostram que a radicão não pode ser devida a transicões livre-livre na região ionizada resultante da interacão do cometa corn 0 vento solar. A emissão seria então devida à radiacão térmica dos gráos da coma do cometa, cuja densidade também foi variável em intervalo de horas. Não foi detetada emissão maser de H2O maior que 4 Jy.

Abraham, Z.; Scalise, E., Jr.; Botti, L. C. L.; Cancoro, A. C. O.; Monteiro Do Vale, J. L.; del Ciampo, L. F.; Tateyama, C. E.; Vilas Boas, J. W. S.; Homor, J. L.; Kaufmann, P.

1987-05-01

277

La Apaicultura de Pequena Escala (Small Scale Beekeeping). Appropriate Technologies for Development. Peace Corps Information Collection & Exchange Manual Series No. M-25.  

ERIC Educational Resources Information Center

This Spanish-language manual is designed to assist Peace Corps volunteers in Spanish-speaking countries in the implementation of small-scale beekeeping programs as a tool for development. Addressed in the individual chapters are bees and humans; project planning; the types and habits of bees; the essence of beekeeping; bee space and beehives;…

Gentry, Curtis

278

Estructura factorial de la Escala de Inteligencia para Niños de Wechsler-Revisada (WISC-R). Un acercamiento desde el ámbito clínico  

Microsoft Academic Search

Structure of intellectual functions in clinical population has been studied with WISC-R, by using the results in tests applied in a Children Mental Health Unit. The last 33 case-histories were chosen from each age group (6 to 15), and a principal component analysis was used. Sex distribution was different at each age, but nearly there were not differences at each

Antonio GALÁN RODRÍGUEZ; Marta LÓPEZ NARBONA; Servicio Andaluz de Salud

279

Observação do abrilhantamento de limbo solar e de estruturas filamentares em 48 ghz utilizando a técnica de regularização adaptativa  

NASA Astrophysics Data System (ADS)

O radiotelescópio do Itapetinga tem sido utilizado em campanhas de observações de explosões solares gerando um grande número de mapas diários em 48 GHz como sub-produto destas observações. A resolução espacial do telescópio de 14m do Itapetinga nesta freqüência é de aproximadamente dois minutos de arco. Estruturas de interesse para análise da atmosfera solar quiescente tais como os filamentos e o anel de abrilhantamento do limbo são de dimensão angular moderada da ordem ou ligeiramente menores que a resolução do telescópio. É conhecido que a convolução da função de espalhamento do telescópio, PSF (padrão de ganho do feixe) borra as estruturas de dimensão angular abaixo do HPBW (largura a meia potência do feixe) e portanto é comum a busca por técnicas de restauração que eliminem pelo menos em parte este borramento. Estudamos a restauração destas radioimagens usando a técnica de regularização adaptativa e os resultados ressaltam estas estruturas espaciais de pequeno contraste. O algoritmo da regularização adaptativa faz uso de k imagens, chamadas protótipos, obtidas através da variação de parâmetros de um filtro de regularização. Para controle da qualidade da restauração utilizamos uma imagem de alta resolução espacial obtida na linha H-a e a PSF do Itapetinga para borrá-la. Pequenos desvios, entre a PSF utilizada para o borramento e a PSF utilizada na restauração, produziram alguns desvios notáveis na imagem restaurada porém a adição de ruído nas simulações de restauração foram mais influentes no cálculo da rugosidade da imagem e portanto mais limitante para a restauração. Apresentamos como nosso primeiro resultado uma imagem em 48 GHz com a presença clara do abrilhantamento de limbo que não estava evidente na imagem original e traços de estruturas filamentares, porém ainda sem grande evidência.

Machado, W. R. S.; Mascarenhas, N.; Costa, J. E. R.; Silva, A. V. R.

2003-08-01

280

75 FR 28610 - Draft EPA's Reanalysis of Key Issues Related to Dioxin Toxicity and Response to NAS Comments  

Federal Register 2010, 2011, 2012, 2013

...For information on the draft report, please contact Linda C. Tuxen, National Center for Environmental Assessment (8601P), U...703-347-8609; facsimile: 703-347-8699; or e-mail: tuxen.linda@epa.gov. SUPPLEMENTARY INFORMATION: I....

2010-05-21

281

75 FR 35800 - Draft EPA's Reanalysis of Key Issues Related to Dioxin Toxicity and Response to NAS Comments  

Federal Register 2010, 2011, 2012, 2013

...For information on the draft report, please contact Linda C. Tuxen, National Center for Environmental Assessment (8601P), U...703-347-8609; facsimile: 703-347-8699; or e-mail: tuxen.linda@epa.gov. Dated: June 17, 2010. Rebecca...

2010-06-23

282

78 FR 46497 - Amendment of Class D and E Airspace, and Establishment of Class E Airspace; Oceana NAS, VA  

Federal Register 2010, 2011, 2012, 2013

...Docket No. 13-AEA-2] Amendment of Class D and E Airspace, and Establishment of Class...SUMMARY: This action amends the Class D and Class E airspace operating hours, and...proposed rulemaking (NPRM) to amend Class D and Class E airspace, and establish...

2013-08-01

283

Considerations in the Integration of Small Aircraft Transportation System Higher Volume Operations (SATSHVO) in the National Airspace System (NAS)  

NASA Technical Reports Server (NTRS)

The Small Aircraft Transportation System Higher Volume Operations (SATS HVO) concept holds the promise for increased efficiency and throughput at many of the nations under-used airports. This concept allows for concurrent operations at uncontrolled airports that under today s procedures are restricted to one arrival or one departure operation at a time, when current-day IFR separation standards are applied. To allow for concurrent operations, SATS HVO proposes several fundamental changes to today's system. These changes include: creation of dedicated airspace, development of new procedures and communications (phraseologies), and assignment of roles and responsibilities for pilots and controllers, among others. These changes would affect operations on the airborne side (pilot) as well as the groundside (controller and air traffic flow process). The focus of this paper is to discuss some of the issues and potential problems that have been considered in the development of the SATS HVO concept, in particular from the ground side perspective. Reasonable solutions to the issues raised here have been proposed by the SATS HVO team, and are discussed in this paper.

Lohr, Gary W.; Williams, Dan; Abbott, Terence; Baxley, Brian; Greco, Adam; Ridgway, Richard

2005-01-01

284

76 FR 57690 - TRICARE; Elimination of the Non-Availability Statement (NAS) Requirement for Non-Emergency...  

Federal Register 2010, 2011, 2012, 2013

...Requirement for Non-Emergency Inpatient Mental Health Care AGENCY: Office of the Secretary...is needed for non-emergency inpatient mental health care in order for a TRICARE Standard...catchment area for non-emergency inpatient mental health care. Currently, the number...

2011-09-16

285

1-W red light generation by intracavity doubling in a 1240 nm GaInNAs semiconductor disk laser  

Microsoft Academic Search

Owing to their good beam quality and high output power, near-infrared semiconductor disk lasers provide an attractive opportunity for visible light generation via frequency conversion. The typical cavity arrangement of a semiconductor disk laser, consisting of a semiconductor multiple quantum well gain mirror and one or more external mirror, offers a convenient configuration for intracavity frequency doubling. Recent progress in

Jussi Rautiainen; Antti Härkönen; Pietari Tuomisto; Janne Konttinen; Lasse Orsila; Mircea Guina; Oleg G. Okhotnikov

2008-01-01

286

A Biometric Latent Curve Analysis of Memory Decline in Older Men of the NAS-NRC Twin Registry  

PubMed Central

Previous research has shown cognitive abilities to have different biometric patterns of age-changes. Here we examined the variation in episodic memory (Words Recalled) for over 6,000 twin pairs who were initially aged 59-75, and were subsequently re-assessed up to three more times over 12 years. In cross-sectional analyses, variation in Education was explained by strong additive genetic influences (~43%) together with shared family influences (~35%) that were independent of age. The longitudinal phenotypic analysis of the Word Recall task showed systematic linear declines over age, but with positive influences of Education and Retesting. The longitudinal biometric estimation yielded: (a) A separation of non-shared environmental influences and transient measurement error (~50%): (b) Strong additive genetic components of this latent curve (~70% at age 60) with increases over age that reach about 90% by age 90. (c) The minor influences of shared family environment (~17% at age 60) were effectively eliminated by age 75. (d) Non-shared environmental effects play an important role over most of the life-span (peak of 42% at age 70) but their relative role diminishes after age 75.

McArdle, John J.; Plassman, Brenda L.

2010-01-01

287

78 FR 21084 - Proposed Amendment of Class D and E Airspace, and Establishment of Class E Airspace; Oceana NAS, VA  

Federal Register 2010, 2011, 2012, 2013

...the Docket Management System (see ADDRESSES section...of Proposed Rulemaking distribution System, which describes the...Oceana TACAN 213[deg] radial extending from the 4...Oceana TACAN 213[deg] radial extending from the...

2013-04-09

288

Temperature dependent photoreflectance and photoluminescence characterization of GaInNAs/GaAs single quantum well structures  

NASA Astrophysics Data System (ADS)

Ga0.69In0.31NxAs1-x/GaAs single quantum well (SQW) structures with three different nitrogen compositions ( x=0%, 0.6%, and 0.9%) have been characterized, as functions of temperature in the range 10-300 K, by the techniques of photoreflectance (PR) and photoluminescence (PL). In PR spectra, clear Franz-Keldysh oscillations (FKOs) above the GaAs band edge and the various excitonic transitions originating from the QW region have been observed. The built-in electric field in the SQW has been determined from FKOs and found to increase with N concentration. The PR signal has been found to decrease for nitrogen incorporated samples when the temperature was lowered due to a weakening of the modulation efficiency induced by carrier localization. A careful analysis of PR and PL spectra has led to the identification of various excitonic transitions, mnH(L), between the mth conduction band state and the nth heavy (light)-hole band state. The anomalous temperature dependent 11H transition energy and linewidth observed in the PL spectra have been explained as originating from the localized states as a result of nitrogen incorporation. The temperature dependence analysis yields information on the parameters that describe the temperature variations of the interband transitions.

Chen, T. H.; Huang, Y. S.; Lin, D. Y.; Tiong, K. K.

2004-12-01

289

ANÁLISE DAS VULNERABILIDADES DE SEGURANÇA EXISTENTES NAS REDES LOCAIS SEM FIO: UM ESTUDO DE CASO DO PROJETO WLACA  

Microsoft Academic Search

The 802.11x standard for wireless network has been widely adopted by large corporations and institutions during its daily tasks, forasmuch the productivity increase produced by flexibility and mobility found in these new sorts of wireless equipments have provided great operational advantages. Nevertheless, there are some important security issues that should be take in consideration while using this new technology. Having

Lidiane Parente Andrade; Daniel Nelo Soares; Mauro Margalho Coutinho; Antônio Jorge; Gomes Abelém

2003-01-01

290

Criterios tomograficos dos gliomas do tronco encefalico nas criancas. (Tomographic criteria of gliomas in the brain stem in infants).  

National Technical Information Service (NTIS)

The relationship between Computed Tomography Imaging, histopathological and prognostic data is evaluated by reviewing 37 cases of brain stem neoplasm in infants. The results indicate a presence of a cystic lesion with solid mural nodule as the single prog...

M. A. Machado Junior M. Bracchi L. D'Incerti A. Passerini

1994-01-01

291

A constituição das creches nas universidades públicas estaduais paulistas e os direitos sociais da mulher e da criança pequena1  

Microsoft Academic Search

In this article, day care centers are focused in the light of the Brazilian Legislation, with a basis on the CLT - Consolidation of the Working Laws - of 1943 and the Federal Constitution of 1988. The Program \\

Sueli Helena de Camargo

292

Excitation energy-dependent nature of Raman scattering spectrum in GaInNAs/GaAs quantum well structures.  

PubMed

The excitation energy-dependent nature of Raman scattering spectrum, vibration, electronic or both, has been studied using different excitation sources on as-grown and annealed n- and p-type modulation-doped Ga1?-?xInxNyAs1?-?y/GaAs quantum well structures. The samples were grown by molecular beam technique with different N concentrations (y = 0%, 0.9%, 1.2%, 1.7%) at the same In concentration of 32%. Micro-Raman measurements have been carried out using 532 and 758 nm lines of diode lasers, and the 1064 nm line of the Nd-YAG laser has been used for Fourier transform-Raman scattering measurements. Raman scattering measurements with different excitation sources have revealed that the excitation energy is the decisive mechanism on the nature of the Raman scattering spectrum. When the excitation energy is close to the electronic band gap energy of any constituent semiconductor materials in the sample, electronic transition dominates the spectrum, leading to a very broad peak. In the condition that the excitation energy is much higher than the band gap energy, only vibrational modes contribute to the Raman scattering spectrum of the samples. Line shapes of the Raman scattering spectrum with the 785 and 1064 nm lines of lasers have been observed to be very broad peaks, whose absolute peak energy values are in good agreement with the ones obtained from photoluminescence measurements. On the other hand, Raman scattering spectrum with the 532 nm line has exhibited only vibrational modes. As a complementary tool of Raman scattering measurements with the excitation source of 532 nm, which shows weak vibrational transitions, attenuated total reflectance infrared spectroscopy has been also carried out. The results exhibited that the nature of the Raman scattering spectrum is strongly excitation energy-dependent, and with suitable excitation energy, electronic and/or vibrational transitions can be investigated. PMID:23190628

Erol, Ayse; Akalin, Elif; Sarcan, Fahrettin; Donmez, Omer; Akyuz, Sevim; Arikan, Cetin M; Puustinen, Janne; Guina, Mircea

2012-01-01

293

Compactação do solo na cultura do feijoeiro. Compactação do solo na cultura do feijoeiro. Compactação do solo na cultura do feijoeiro. Compactação do solo na cultura do feijoeiro. Compactação do solo na cultura do feijoeiro. I: efeitos nas propriedades físico-hídricas do solo I: efeitos nas propriedades físico-hídricas do solo I: efeitos nas propriedades físico-hídricas do solo  

Microsoft Academic Search

-3 . As propriedades de transmissão de água foram determinadas com infiltrômetros de tensão, para as cargas de pressão de -0,5; -2,0 e -6,0 cm de água. O aumento da densidade do solo aumentou sua resistência à penetração e reduziu linearmente a porosidade total e a macroporosidade. Houve ainda, redução no tamanho dos poros para o fluxo de água, reduzindo

Luís F. Stone; Cleber M. Guimarães; José A. A. Moreira

294

Large-Scale Physical Modeling of Water Injection into Geothermal Reservoirs and Correlation to Self Potential Measurements Modelación Física a Gran Escala de Inyecciones de Agua en Depósitos Geotérmicos y Correlación con Medidas de Potencial Natural  

Microsoft Academic Search

Laboratory measurements of electric self potentials resulting from water injection through a known flow path in a 260 mm cube of Nugget sandstone are used to calibrate a new large-scale testing device that simulates the in-situ conditions at an injection point in a geothermal reservoir. Modeled in-situ temperatures were 20?C and 150?C, while injection pressures were varied from 1 to

Jeffrey R. Moore; Steven D. Glaser; H. Frank Morrison

295

Criterios Para Correcao Planimetrica E Altimetrica de Mapas Restituidos a Partir de Fotografias Aereas Em Escala 1:100000 (Criteria for Planimetric and Altimetric Correction of Maps Restituted from Aerial Photographs in 1:100,000 Scale).  

National Technical Information Service (NTIS)

The aim is to introduce a simple method for correcting the scale of level curve charts restituted from aerial photographs in a 1:100,000 approximate scale used for planning the Pitinga mine facilities. The mine is located some 250 km north of Manaus (AM-B...

F. A. Dupas

1986-01-01

296

Aplicacao DA Cartografia Digital NA Atualizacao Tematica de Cartas de Media E Pequena Escala Utilizando Dados Orbitais (Application of Digital Cartography Updating Middle and Small Scale Thematic Maps Using Orbital Data).  

National Technical Information Service (NTIS)

This research includes a methodology for generating polygonal maps from Landsat data using computer graphics techniques. The polygonal maps represent different classes which can be used to update thematic maps. For this purpose digital data processing pro...

C. A. Goncalvesdearaujo

1987-01-01

297

Small is Beautiful: Small-scale phenomenological research for counselor self-development \\/ Klein ist schön: Eine phänomenologische Kleinstudie als Selbstentwicklung des Beraters \\/ Lo pequeño es hermoso: Investigación fenomenológica a pequeña escala para el desarrollo personal del counselor  

Microsoft Academic Search

This article offers an example of how small-scale, phenomenological research can enable personal and professional development in person-centered experiential psychotherapists and counselors. It gives a phenomenological account of the author's experience of meeting with a co-researcher who has anorexia, and of the impact of this exploration on the author's ability to accord unconditional positive regard to clients with anorexia. The

Richard Worsley

2003-01-01

298

Efeito da radiacao gama de cobalto 60 nas proteinas do cristalino. (Effect of (sup 60) Co gamma radiation on crystalline proteins).  

National Technical Information Service (NTIS)

In order to study the effects of (sup 6) (sup 0) Co gamma radiation on crystalline proteins an in vitro system was set up. For that, aqueous solutions from bovine crystalline were used irradiated with 0, 5.000, 10.000, 15.000, 20.000 and 25.000 Gy. The tr...

D. M. L. Bernardes

1991-01-01

299

An analysis of Hall mobility in as-grown and annealed n- and p-type modulation-doped GaInNAs/GaAs quantum wells.  

PubMed

In this study, we investigate the effect of annealing and nitrogen amount on electronic transport properties in n- and p-type-doped Ga0.68In0.32NyAs1 - y/GaAs quantum well (QW) structures with y?=?0%, 0.9%, 1.2%, 1.7%. The samples are thermal annealed at 700°C for 60 and 600 s, and Hall effect measurements have been performed between 10 and 300 K. Drastic decrease is observed in the electron mobility of n-type N-containing samples due to the possible N-induced scattering mechanisms and increasing effect mass of the alloy. The temperature dependence of electron mobility has an almost temperature insensitive characteristic, whereas for p-type samples hole mobility is decreased drastically at T?>?120 K. As N concentration is increased, the hole mobility also increased as a reason of decreasing lattice mismatch. Screening effect of N-related alloy scattering over phonon scattering in n-type samples may be the reason of the temperature-insensitive electron mobility. At low temperature regime, hole mobility is higher than electron mobility by a factor of 3 to 4. However, at high temperatures (T?>?120 K), the mobility of p-type samples is restricted by the scattering of the optical phonons. Because the valance band discontinuity is smaller compared to the conduction band, thermionic transport of holes from QW to the barrier material, GaAs, also contributes to the mobility at high temperatures that results in a decrease in mobility. The hole mobility results of as-grown samples do not show a systematic behavior, while annealed samples do, depending on N concentration. Thermal annealing does not show a significant improvement of electron mobility. PMID:23009196

Sarcan, Fahrettin; Donmez, Omer; Gunes, Mustafa; Erol, Ayse; Arikan, Mehmet Cetin; Puustinen, Janne; Guina, Mircea

2012-01-01

300

Influence of nitrogen on hole effective mass and hole mobility in p-type modulation doped GaInNAs/GaAs quantum well structures  

NASA Astrophysics Data System (ADS)

Nitrogen dependence of hole effective mass and hole mobility in p-type modulation doped Ga0.68In0.32NyAs1-y/GaAs quantum well structures with y = 0, 0.009, 0.012, 0.017 are investigated using magnetotransport and Hall effect measurements. Observed N-dependent reduction of the hole effective mass is explained by stronger confinement of holes. Hole effective mass is also found to have hole density dependence due to the strain-induced valance band non-parabolicity. A tendency to decrease in hole effective mass upon annealing can be attributed to the reduction of well width and/or decrease in hole density. A significant improvement in low temperature hole mobility is observed after annealing.

Sarcan, F.; Donmez, O.; Erol, A.; Gunes, M.; Arikan, M. C.; Puustinen, J.; Guina, M.

2013-08-01

301

An analysis of Hall mobility in as-grown and annealed n- and p-type modulation-doped GaInNAs/GaAs quantum wells  

PubMed Central

In this study, we investigate the effect of annealing and nitrogen amount on electronic transport properties in n- and p-type-doped Ga0.68In0.32NyAs1 ? y/GaAs quantum well (QW) structures with y?=?0%, 0.9%, 1.2%, 1.7%. The samples are thermal annealed at 700°C for 60 and 600 s, and Hall effect measurements have been performed between 10 and 300 K. Drastic decrease is observed in the electron mobility of n-type N-containing samples due to the possible N-induced scattering mechanisms and increasing effect mass of the alloy. The temperature dependence of electron mobility has an almost temperature insensitive characteristic, whereas for p-type samples hole mobility is decreased drastically at T?>?120 K. As N concentration is increased, the hole mobility also increased as a reason of decreasing lattice mismatch. Screening effect of N-related alloy scattering over phonon scattering in n-type samples may be the reason of the temperature-insensitive electron mobility. At low temperature regime, hole mobility is higher than electron mobility by a factor of 3 to 4. However, at high temperatures (T?>?120 K), the mobility of p-type samples is restricted by the scattering of the optical phonons. Because the valance band discontinuity is smaller compared to the conduction band, thermionic transport of holes from QW to the barrier material, GaAs, also contributes to the mobility at high temperatures that results in a decrease in mobility. The hole mobility results of as-grown samples do not show a systematic behavior, while annealed samples do, depending on N concentration. Thermal annealing does not show a significant improvement of electron mobility.

2012-01-01

302

An estimate of the enroute noise of an advanced turboprop airplane NASA-TM-87302 E-3020 NAS 1.15:87302 HC A02/MF A01  

NASA Technical Reports Server (NTRS)

The enroute noise of an Advanced Turboprop powered aircraft was estimated. The measured noise levels were roughly equivalent in annoyance to the noise 15.24 m from an automobile traveling at 80 km/h. It is felt that these levels would not illicit noise complaints from urban areas during the day but might be a slight annoyance in rural areas or in urban areas at night. Although it is not felt that the enroute noise is a major problem, it is indicated that a reduction in the enroute noise could improve the acceptability of advance turboprop airplanes.

Dittmar, J. H.

1986-01-01

303

SISTEMAS DE COLHEITA DA CANA-DE-AÇÚCAR E ALTERAÇÕES NAS PROPRIEDADES FÍSICAS DE UM SOLO PODZÓLICO AMARELO NO ESTADO DO ESPÍRITO SANTO1  

Microsoft Academic Search

A long term (1989-1994) experiment with sugar cane (RB 739735) was carried out, in Linhares, ES, Brazil, in order to evaluate the effect of two systems of sugar cane harvesting: the first with previous burning (burned cane), and the second with crop residue remaining on the soil surface (green cane), on some physical properties of a tableland Yellow Podzolic soil.

MARCOS BACIS CEDDIA; LÚCIA HELENA CUNHA; DOS ANJOS; EDUARDO LIMA; ALEXANDRE RAVELLI NETO

304

Magnetotransport study on as-grown and annealed n- and p-type modulation-doped GaInNAs/GaAs strained quantum well structures  

NASA Astrophysics Data System (ADS)

We report the observation of thermal annealing- and nitrogen-induced effects on electronic transport properties of as-grown and annealed n- and p-type modulation-doped Ga1 - x In x N y As1 - y ( x = 0.32, y = 0, 0.009, and 0.012) strained quantum well (QW) structures using magnetotransport measurements. Strong and well-resolved Shubnikov de Haas (SdH) oscillations are observed at magnetic fields as low as 3 T and persist to temperatures as high as 20 K, which are used to determine effective mass, 2D carrier density, and Fermi energy. The analysis of temperature dependence of SdH oscillations revealed that the electron mass enhances with increasing nitrogen content. Furthermore, even the current theory of dilute nitrides does not predict a change in hole effective mass; nitrogen dependency of hole effective mass is found and attributed to both strain- and confinement-induced effects on the valence band. Both electron and hole effective masses are changed after thermal annealing process. Although all samples were doped with the same density, the presence of nitrogen in n-type material gives rise to an enhancement in the 2D electron density compared to the 2D hole density as a result of enhanced effective mass due to the effect of nitrogen on conduction band. Our results reveal that effective mass and 2D carrier density can be tailored by nitrogen composition and thermal annealing-induced effects.

Dönmez, Ömer; Sarcan, Fahrettin; Erol, Ayse; Gunes, Mustafa; Arikan, Mehmet Çetin; Puustinen, Janne; Guina, Mircea

2014-03-01

305

A Review of the NAS Manpower Studies Subcontracted by the National Academy of Sciences Committee on Health Care Resources in the Veterans Administration. Volume I.  

National Technical Information Service (NTIS)

The two volume study was performed by the Human Resources Management, Inc., for the Veterans Administration. The nature of this two volume study is to review and analyze the feasibiity, costs, and expected time frame for implementation of four sub-studies...

1977-01-01

306

Avaliando os impactos microeconômicos das fusões e aquisições nas indústrias de energia no mundo: uma análise para a década de 90  

Microsoft Academic Search

The energy industries have witnessed a significant growth of global mergers and acquisitons (M&As) process in the 1990´s. According to Unctad statistics, the total amount of global M&A deals (domestic and cross borders) on the electric, oil and gas sectors has recorded US$ 329 billions on the 1990-1999 period. The present paper sheds light on M&A process occurred on the

Helder Queiroz Pinto Jr.; Mariana Iootty

2005-01-01

307

Crescimento de recØm-nascidos prØ-termo nas primeiras 12 semanas de vida Growth of preterm newborns during the first 12 weeks of life  

Microsoft Academic Search

Objective: To assess the somatic growth of preterm newborns through growth curves during the first 12 weeks of life. Method: A longitudinal and prospective study was carried out at two state operated maternity hospitals in the city of Belo Horizonte. Three hundred and forty preterm infants with birth weight less than 2,500 g were weekly evaluated in terms of body

M. Anchieta; C. Xavier; Enrico A. Colosimo

308

Pratt & Whitney/Boeing Engine Validation of Noise Reduction Concepts Final Report for NASA Contract NAS3-97144, Phase 2  

NASA Technical Reports Server (NTRS)

This report presents results of the work completed in Phase 2 of the Engine Validation of Noise Reduction Concepts (EVNRC) contract. The purpose of the program is to validate, through engine testing, advanced noise reduction concepts aimed at reducing engine noise up to 6 EPNdB and improving nacelle suppression by 50 percent relative to 1992 technology. Phase 1 of the program is completed and is summarized in NASA/CR-2014-218088.

Bock, Larry A.; Hauser, Joseph E.; Mathews, Douglas C.; Topol, David A.; Bielak, Gerald W.; Lan, Justin H.; Premo, John W.

2014-01-01

309

Sistema de Web Mapping para Geologia Médica  

Microsoft Academic Search

Resumo - Este trabalho apresenta um sistema de Web Mapping para pesquisa em Geologia Médica, no qual, por meio de uma navegação em mapas interativos, epidemiologistas visualizam as distribuições espaciais de teores de elementos químicos em águas não tratadas (bacias hidrográficas) e dos coeficientes de morbi-mortalidade por doenças nos municípios. A sobreposição desses temas compõe um mapa onde se podem

Humberto Cereser Ibañez; Marilea Vieira de Camargo; Hélio Pedrini

310

Cloning of Nicotianamine Synthase Genes, Novel Genes Involved in the Biosynthesis of Phytosiderophores  

Microsoft Academic Search

Nicotianamine synthase (NAS), the key enzyme in the biosyn- thetic pathway for the mugineic acid family of phytosiderophores, catalyzes the trimerization of S-adenosylmethionine to form one molecule of nicotianamine. We purified NAS protein and isolated the genes nas1, nas2, nas3, nas4, nas5-1, nas5-2, and nas6, which encode NAS and NAS-like proteins from Fe-deficient barley (Horde- um vulgare L. cv Ehimehadaka

Kyoko Higuchi; Kazuya Suzuki; Hiromi Nakanishi; Hirotaka Yamaguchi; Naoko-Kishi Nishizawa; Satoshi Mori

1999-01-01

311

A compact and low cost TT&C S-Band Ground Station for low orbit satellites  

NASA Astrophysics Data System (ADS)

Instituto Nacional de Pesquisas Espaciais (INPE's) S-Band Ground Station for satellite control and monitoring is revised consdiering the current software and hardware technology. A Ground Station concept for low orbit satellites is presented. The front-end uses a small antenna and low cost associated equipment without loss of performance. The baseband equipment is highly standardized and developed on a personal computer IBM compatible using extensively Digital Signal Processing (DSP). A link budget for ranging, telecommand and telemetry is also presented.

Pacola, Luiz C.; Ferrari, Carlos A.

312

Inexistência de Diferenças de Sexo no Fator g (Inteligência Geral) e nas Habilidades Específicas em Crianças de Duas Capitais Brasileiras There are no Sex Differences on g Factor and Specific Abilities in Children from Two Brazilian Capitals  

Microsoft Academic Search

Resumo O presente trabalho pretendeu examinar diferenças relacionadas ao sexo no fator g (inteligência geral) e em habilidades específicas em crianças de duas cidades brasileiras: Belo Horizonte e Porto Alegre. No caso da amostra mineira (n=1,316), a idade compreendeu entre 5 e 11 anos de idade examinada através de uma bateria de testes a qual incluiu instrumentos de inteligência (Raven,

Carmen E. Flores-Mendoza; Marcela Mansur-Alves; Álvaro José Lelé; Denise Ruschel Bandeira

313

IX SEMEAD - Agosto de 2008 Tema: Empreendedorismo nas Organizações Área Temática: Organizações do 3º Setor AS PERCEPÇÕES SOBRE AS DIMENSÕES DE ATUAÇÃO DO ASSOCIATIVISMO EMPRESARIAL E SUAS CONTRIBUIÇÕES PARA O JOVEM EMPREENDEDOR DA CIDADE DE SÃO PAULO  

Microsoft Academic Search

The presented paper aims to analyze the perception on 3 dimensions of business associateship (management skill, business relationship and representativeness) by young entrepreneurs, besides putting in context the associativity movement in Brasil. In order to do so, the article presents a brief theoretical review, a few data on the entrepreneurial context in Brasil and finally a quantitative survey research introduces

CARLOS EDUARDO; MACHADO MUNHOZ; FAESP. IPCA

314

Avaliação do índice de temperatura de globo negro e umidade e desempenho de suínos nas fases de crescimento e terminação criados em sistemas em camas sobrepostas em condições de verão  

Microsoft Academic Search

RESUMO - Um estudo foi realizado com o objetivo de avaliar o sistema de criação em camas sobrepostas de maravalha e de casca de arroz, em comparação ao piso tradicional de concreto e sua influência no desempenho dos animais com base no ITGU (Índice de Temperatura de Globo negro e Umidade), no ganho de peso, no consumo de ração, na

Ilda de Fátima Ferreira Tinôco; Cecília de Fátima Souza; Paulo Armando Victoria de Oliveira; Robson Mendes de Paulo; Josiane Aparecida Campos; Cinara da Cunha Siqueira Carvalho; Marcelo Bastos Cordeiro

2007-01-01

315

Influence of lean body mass on cardiopulmonary repercussions during the six-minute walk test in patients with COPD* Influência da massa magra corporal nas repercussões cardiopulmonares durante o teste de caminhada de seis minutos em pacientes com DPOC  

Microsoft Academic Search

Objective: Although lean body mass (LBM) has been associated with mortality in patients with COPD, its influence on functional limitation is not clear. The objective of this study was to analyze the cardiopulmonary variables in COPD patients with or without LBM depletion, prior to and after the six-minute walk test (6MWT). Methods: We evaluated COPD patients, 32 with LBM depletion

Nilva Regina; Gelamo Pelegrino; Paulo Adolfo Lucheta; Fernanda Figueirôa Sanchez; Márcia Maria Faganello; Renata Ferrari; Irma de Godoy

2009-01-01

316

Influência da massa magra corporal nas repercussões cardiopulmonares durante o teste de caminhada de seis minutos em pacientes com DPOC* Influence of lean body mass on cardiopulmonary repercussions during the six-minute walk test in patients with COPD  

Microsoft Academic Search

Objective: Although lean body mass (LBM) has been associated with mortality in patients with COPD, its influence on functional limitation is not clear. The objective of this study was to analyze the cardiopulmonary variables in COPD patients with or without LBM depletion, prior to and after the six-minute walk test (6MWT). Methods: We evaluated COPD patients, 32 with LBM depletion

Nilva Regina; Gelamo Pelegrino; Paulo Adolfo Lucheta; Fernanda Figueirôa Sanchez; Márcia Maria Faganello; Renata Ferrari; Irma de Godoy

2009-01-01

317

PUBLICAÇÕES CIENTÍFICAS EM DST, HIV E AIDS: DESCRIÇÃO DE PROCEDIMENTOS BIOÉTICOS NAS RECOMENDAÇÕES PARA OS AUTORES E EM ARTIGOS SELECIONADOS STD, HIV AND AIDS SCIENTIFIC PUBLICATIONS: DESCRIPTION OF BIOETHICAL PROCEDURES IN THE INSTRUCTIONS FOR THE AUTHORS AND IN SELECTED PAPERS  

Microsoft Academic Search

Introduction: Bioethics in research with human participants has permitted to address ethical aspects of the health field. STD, HIV and AIDS research is currently amongst the more productive research fields. Objective: To review scientific journals and selected papers in order to evaluate the presence of ethical requirements and description of ethical procedures. Methods: Bibliographic review of an electronic database (SciELO)

Prisla Ü Calvetti; Erno Harzheim; José Lândio Viana; Cíntia Germany; Mauro C Ramos

318

Geoprocessamento aplicado ao mapeamento dos impactos socioambientais decorrentes das formas de uso da terra nas Áreas de Preservação Permanente (APPs) da Represa de Salto Grande no município de Americana (SP)  

Microsoft Academic Search

The Dam of Salto Grande, occupying an area of 10.5 km2, is located in the hydrographical basin of the Atibaia River, important tributary of the Piracicaba River, in the State of São Paulo. It takes care of, in the present time, to the inhabitants of the cities of Americana, Paulínia and Nova Odessa, that also use the source for activities

Joyce Rodrigues da Cruz

319

A Pos-Graduacao Nas Ciencias Humanas e o Paradigma da Medicina: A Era da Especializacao. (Post-Graduation in the Human Sciences and the Paradigm of Medicine: The Era of Specialization.)  

ERIC Educational Resources Information Center

Reflects on the current tendency in Brazilian higher education for greater and greater specialization, particularly in human sciences and in medicine. Calls for less specialization and a more historic and general preparation, especially in teacher education. (BT)

Costa, Celio Juvenal

2000-01-01

320

REPRESENTAÇÕES SOCIAIS DE DST\\/AIDS PARA ADOLESCENTES DE UMA INSTITUIÇÃO ABRIGO COM EXPERIÊNCIA PREGRESSA DE VIDA NAS RUAS DA CIDADE DE GOIÂNIA SOCIAL REPRESENTATION OF STD\\/AIDS FOR SHELTERED ADOLESCENTS WITH LIFE EXPERIENCE IN THE STREETS OF GOIÂNIA  

Microsoft Academic Search

Introduction: adolescents in street situation likely exposed to STD\\/AIDS, because the street world is favorable for violence, use and traffic of drugs, sexual exploration. Objective: in this study we sough to identify and to analyze the social representations of prevention DST\\/Aids for a group of ado- lescents with experience of life in the streets, living in a shelter institution in

Ida K Borges; Marcelo Medeiros

321

Caracteristicas DA Drenagem Determinadas Em Fotografias Aerease Do Relevo Determinadas Em Cartas Planialtimetricas de Escalas Diferentes Para Tres Solos Do Estado de Sao Paulo (Characteristics of Drainage Determinations in Aerial Photographs and Relief Determination on Different Scales Planialtimetric Charts for Three Soils in the State of Sao Paulo).  

National Technical Information Service (NTIS)

Based on the interpretation of vertical aerial photographs on a 1:35,000 scale, the characterization was made of the drainage standards from three different soils of the State of Sao Paulo (red-yellow latosol, red-yellow podzol, and litosol) and the varia...

R. Angulofilho V. A. Demetrio G. V. Defranca

1986-01-01

322

Nitrogen Oxyanion-dependent Dissociation of a Two-component Complex That Regulates Bacterial Nitrate Assimilation*  

PubMed Central

Nitrogen is an essential nutrient for growth and is readily available to microbes in many environments in the form of ammonium and nitrate. Both ions are of environmental significance due to sustained use of inorganic fertilizers on agricultural soils. Diverse species of bacteria that have an assimilatory nitrate/nitrite reductase system (NAS) can use nitrate or nitrite as the sole nitrogen source for growth when ammonium is limited. In Paracoccus denitrificans, the pathway-specific two-component regulator for NAS expression is encoded by the nasT and nasS genes. Here, we show that the putative RNA-binding protein NasT is a positive regulator essential for expression of the nas gene cluster (i.e. nasABGHC). By contrast, a nitrogen oxyanion-binding sensor (NasS) is required for nitrate/nitrite-responsive control of nas gene expression. The NasS and NasT proteins co-purify as a stable heterotetrameric regulatory complex, NasS-NasT. This protein-protein interaction is sensitive to nitrate and nitrite, which cause dissociation of the NasS-NasT complex into monomeric NasS and an oligomeric form of NasT. NasT has been shown to bind the leader RNA for nasA. Thus, upon liberation from the complex, the positive regulator NasT is free to up-regulate nas gene expression.

Luque-Almagro, Victor M.; Lyall, Verity J.; Ferguson, Stuart J.; Roldan, M. Dolores; Richardson, David J.; Gates, Andrew J.

2013-01-01

323

75 FR 57828 - Agency Information Collection Activities: Requests for Comments; Clearance of Renewed Approval of...  

Federal Register 2010, 2011, 2012, 2013

...Renewed Approval of Information Collection: NAS Data Release Request AGENCY: Federal Aviation...user's request for National Airspace (NAS) data from FAA systems and equipment...OMB Control Number: 2120-0668. Title: NAS Data Release Request. Form Numbers:...

2010-09-22

324

76 FR 4743 - Agency Information Collection Activities: Requests for Comments; Clearance of Renewed Approval of...  

Federal Register 2010, 2011, 2012, 2013

...Approval of Information Collection(s): NAS Data Release Request AGENCY: Federal Aviation...user's request for National Airspace (NAS) data from FAA systems and equipment...OMB Control Number: 2120-0668. Title: NAS Data Release Request. Form Numbers:...

2011-01-26

325

41 CFR Appendix A to Subpart E of... - 3-Key Points and Principles  

Code of Federal Regulations, 2013 CFR

...of the Act allows the National Academy of Sciences (NAS) and the National Academy of Public Administration...if different policies and procedures are adopted by NAS and NAPA? A. Yes. NAS and NAPA are completely separate...

2013-07-01

326

78 FR 66904 - Notice of Availability of Record of Decision for Naval Air Station Key West Airfield Operations, FL  

Federal Register 2010, 2011, 2012, 2013

...airfield operations at Naval Air Station (NAS) Key West by accomplishing the proposed...Final Environmental Impact Statement for NAS Key West Airfield Operations, dated July...Facilities Engineering Command Southeast, Attn: NAS Key West Airfield Operations EIS...

2013-11-07

327

77 FR 16434 - Revocation of Multiple Domestic, Alaskan, and Hawaiian Compulsory Reporting Points  

Federal Register 2010, 2011, 2012, 2013

...elsewhere within the National Airspace System (NAS). DATES: Effective date 0901 UTC, May...for navigation fixes elsewhere within the NAS. To overcome confusion and flight safety...Hawaiian Reporting Points contained in the NAS. Environmental Review The FAA has...

2012-03-21

328

77 FR 43275 - Extension of Public Comment Period for the Draft Environmental Impact Statement for Naval Air...  

Federal Register 2010, 2011, 2012, 2013

...Statement (EIS) for Naval Air Station (NAS) Key West Airfield Operations, Florida...Facilities Engineering Command Southeast, NAS Key West Air Operations EIS Project Manager, P.O. Box 30, Building 903, NAS Jacksonville, FL 32212....

2012-07-24

329

75 FR 68970 - Amendment of Using Agency for Restricted Areas R-4002, R-4005, R-4006 and R-4007; MD  

Federal Register 2010, 2011, 2012, 2013

...U.S. Navy, Commanding Officer, NAS Patuxent River, MD.'' This is an administrative...U.S. Navy, Commanding Officer, NAS Patuxent River, MD'' for restricted area...River, MD, from ``Commanding Officer, NAS Patuxent River, MD,'' to...

2010-11-10

330

76 FR 44579 - Notice of Availability of Environmental Assessment for Strike Fighter Realignment at Naval Air...  

Federal Register 2010, 2011, 2012, 2013

...of strike fighter assets at Naval Air Station (NAS) Lemoore. Dates and Addresses: Written comments...east coast FA-18 E/F Super Hornet squadrons to NAS Lemoore, and transitioning five NAS Lemoore based FA-18 Hornet squadrons to...

2011-07-26

331

Determination and characterization of oxy-naphthenic acids in oilfield wastewater.  

PubMed

Oxy-naphthenic acids (oxy-NAs) are one of the major components of NA mixtures in wastewaters from petroleum industries. The limited available data indicated that oxy-NAs were considered as a potential marker for the degradation of NAs, and some oxy-NAs exhibited endocrine disrupting activities. However, the lack of information on the structures and occurrences of oxy-NAs in oilfield wastewaters limited the interpretations of the biotransformation pathways of NAs and structure-specific toxicity. A sensitive method for simultaneous determination of oxy-NAs together with NAs was developed by combining MAX extraction column and UPLC-ESI(-)-QTOF-MS. The 2000-fold SPE preconcentration step was highly specific for acids and the prewash solvent greatly reduced matrix effects in the UPLC-ESI(-)-QTOF-MS analysis, resulting in an increase in sensitivity down to detection limits in the ng/L range. To provide structural information within each oxy-NA isomer class, a new method was developed by derivatizing oxy-NAs with dansyl chloride by UPLC-ESI(+)-QTOF-MS. The molecular ion dansyl derivatives from the corresponding oxy-NAs and characteristic fragmentation ions, not detected before derivatization, were observed in the extracts of oilfield wastewater, providing evidence that O3-NAs and O4-NAs were mainly composed of OH-NAs and (OH)2-NAs, respectively. Semiquantification of oxy-NAs and NAs in various oilfield wastewaters revealed NAs, O3-NAs, and O4-NAs present at concentrations of 187-397, 44-146, and 40-108 ?g/L, respectively. Significantly different profiles of NA mixtures were observed in petroleum refinery wastewater and oil sands extraction water, but the profile of oxy-NAs was similar to NAs in different wastewaters suggesting the existence of biotransformation between NAs and oxy-NAs in the environment, and hydroxylation could be one of the major biotransformation pathways of NAs. PMID:23859600

Wang, Beili; Wan, Yi; Gao, Yingxin; Yang, Min; Hu, Jianying

2013-08-20

332

Estudo do sector eléctrico e electrónico: uma análise desagregada, ao nível dos 40 principais produtos do comércio bilateral comunitário e ao nível das principais empresas, para o período 1980 - 1992  

Microsoft Academic Search

Neste artigo faz-se: I) a caracterização do sector eléctrico - electrónico utilizando vários indicadores, dos quais destacamos as medidas de capital humano, em termos de stock e de fluxo, as medidas de concentração industrial e da escala mínima de eficiência (economias de escala) as medidas do peso das PMEs e as medidas da inovação tecnológica; ÍI) o ranking dos principais

Horácio Crespo Faustino

1995-01-01

333

Challenges of Conflicting School Reforms: Effects of New American Schools in a High-Poverty District.  

ERIC Educational Resources Information Center

This study compared New American Schools (NAS) classrooms to non-NAS classrooms in the high poverty San Antonio, Texas, school district. NAS promoted whole-school reform to address lagging achievement and lackluster school reform attempts that produced little meaningful change. The study investigated whether NAS designs extended beyond changes in…

Berends, Mark; Chun, JoAn; Schuyler, Gina; Stockly, Sue; Briggs, R. J.

334

DUSTY NUCLEAR DISKS AND FILAMENTS IN EARLY TYPE GALAXIESa a BASED ON OBSERVATIONS WITH THE NASA\\/ESA HUBBLE SPACE TELESCOPE, OBTAINED AT THE SPACE TELESCOPE SCIENCE INSTITUTE, WHICH IS OPERATED BY THE ASSOCIATION OF UNIVERSITIES FOR RESEARCH IN ASTRONOMY, INC. UNDER NASA CONTRACT NO. NAS5-26555  

Microsoft Academic Search

We examine the dust properties of a nearby distance-limited sample of early type galaxies using the WFPC2 of the Hubble Space Telescope. Dust is detected in 29 out of 67 galaxies (43%), including 12 with small nuclear dusty disks. In a separate sample of 40 galaxies biased for the detection of dust by virtue of their detection in the IRAS

H. D. Tran; Z. Tsvetanov; H. C. Ford; J. Davies; W. Jaffe

335

Torio: uma das aplicacoes analiticas da ativacao neutronica e espectrometria alfa no CDTN nas ultimas tres decadas do Brasil. (Thorium: one of the analytical techniques in neutronic activation and alpha spectrometry of the CDTN (Brazilian Nuclear Technology Development Center) in the last three decades).  

National Technical Information Service (NTIS)

For long years, the CDTN (Brazilian Nuclear Technology Development Center ) has applied several analytical techniques in the thorium determination. This work is about the evolution of the neutronic activation in the thorium 232 analysis from the 1960's to...

M. A. B. Menezes C. V. S. Sabino

1994-01-01

336

Relation Between Ocean Temperature and Ocean Level Change in the Tropical Atlantic and Precipitation in the Amazon Region of Northeast Brazil Relacoes Entre Temperatura DA Agua Do Mar E Divergencia AO Nivel Do Mar No Atlantico Tropical E Precipitacao NAS Regioes Amazonica E Nordeste Do Brasil.  

National Technical Information Service (NTIS)

The precipitation series for the rainy season over northeastern Brazil (Fortaleza and Quixeramobim) and the Amazon Region (manaus, Belem, Taperinha, Conceicao do Araguaia and Alto Tapajos) and a 48 station average of normalized departure of annual precipi...

M. T. Kagano

1982-01-01

337

THE HUBBLE HIGHER-z SUPERNOVA SEARCH: SUPERNOVAE TO z ? 1.6 AND CONSTRAINTS ON TYPE Ia PROGENITOR MODELS a a BASED ON OBSERVATIONS WITH THE NASA\\/ESA HUBBLE SPACE TELESCOPE, OBTAINED AT THE SPACE TELESCOPE SCIENCE INSTITUTE, WHICH IS OPERATED BY AURA, INC., UNDER NASA CONTRACT NAS 5-26555  

Microsoft Academic Search

We present results from the Hubble Higher-z Supernova Search, the first space-based open field survey for supernovae (SNe). In cooperation with the Great Observatories Origins Deep Survey, we have used the Hubble Space Telescope with the Advanced Camera for Surveys to cover ? 300 square arcmin in the area of the Chandra Deep Field South and the Hubble Deep Field

Louis-Gregory Strolger; Adam G. Riess; Tomas Dahlen; Mario Livio; Nino Panagia; Peter Challis; John L. Tonry; Alexei V. Filippenko; Ryan Chornock; Henry Ferguson; Anton Koekemoer; Bahram Mobasher; Mark Dickinson; Mauro Giavalisco; Stefano Casertano; Richard Hook; Stephane Blondin; Bruno Leibundgut; Mario Nonino; Piero Rosati; Hyron Spinrad; Charles C. Steidel; Daniel Stern; Peter M. Garnavich; Thomas Matheson; Norman Grogin; Ann Hornschemeier; Claudia Kretchmer; Victoria G. Laidler; Kyoungsoo Lee; Ray Lucas; Duilia de Mello; Leonidas A. Moustakas; Swara Ravindranath; Marin Richardson; Edward Taylor

338

CONFLITOS E DESAFIOS NA COMERCIALIZAÇÃO DE PRODUTOS ORGÂNICOS NAS GRANDES REDES DE SUPERMERCADOS: O CASO DOS PROCESSADOS ORGÂNICOS NO RIO GRANDE DO SUL prcs1064@yahoo.com.br Apresentação Oral-Estrutura, Evolução e Dinâmica do s Sistemas Agroalimentares e Cadeias Agroindustriais  

Microsoft Academic Search

The article takes as its basis the current investig ation in the state of Rio Grande do Sul, where the organic agriculture presents an old tradition w hich has begun with the environmentalist movements, since the 1970's. The organic processed commercialization is analyzed in the supermarket chains Carrefour and Wall-Mart in the city of Porto Alegre. These chains were chosen

ROBERTO CARDOSO DA SILVEIRA

339

Estudo do campo hiperfino magnetico no (sup 181)Ta nos sitios de Nb e V nas ligas de Heusler Co(sub 2)YAl (Y=Nb,V). (Magnetic hyperfine fields on (sup 181)Ta at the Nb and V sites in Heusler alloys Co(sub 2)YAl (Y=Nb,V)).  

National Technical Information Service (NTIS)

Magnetic hyperfine fields (MHF) acting on sup(181)Ta at the Nb and V sites have been determined in the Heusler alloys Co sub(2) NbAl and Co sub(2) VAl by the time differential perturbed angular correlation (TDPAC) technique utilizing the well known 133-48...

W. Pendl Junior

1990-01-01

340

O Passado como Nacao: Imagens do Imperio nas Falas Reacionarias dos Anos 30 e 40 do Seculo XX: Uma Pequena Arqueologia do Debate Publico e Privado (The Past as Nation: Images of the Empire in the Reactionary Words of the 30s and 40s in the 20th Century: A Small Archaeology of the Public Debate versus the Private One).  

ERIC Educational Resources Information Center

Suggests an archaeology of the public debate versus the private one in Brazil through analysis of the reactionary speech of a religious leader, Dom Jose Mauricio da Rocha, which produced innumerable representations of the Brazilian Empire. (PA)

de Freitas, Marcos Cezar

1998-01-01

341

Life support systems and optimal isotope composition in cosmonaut habitats for long-term missions 1 1 The work is carried out by partial support of contract NAS15-10 110. 2 2 Paper IAF96-G4.06 presented at 47th International Astronautical Congress, 7–11 October 1996, Beijing, China  

Microsoft Academic Search

Differences in the isotope content of the biogenous chemicals of cosmonaut habitats are given a theoretical consideration. Rationale is given to the hypothesis according to which the biochemical and biophysical processes in plants, animals, and humans must be impacted by the isotopes of all the biogenous chemicals in cosmonaut habitats. Organisms were found to persistently make preference of lighter fractions

I. E. Siniak; A. I. Grigoriev

1998-01-01

342

N-Acetylserotonin and Aging-Associated Cognitive Impairment and Depression  

PubMed Central

Normal brain aging is associated with depression and cognitive decline. One of the mechanisms of aging-associated emotional and cognitive impairment might be the down-regulation of biosynthesis of N-acetylserotonin (NAS), one of the methoxyindole derivatives of tryptophan (TRP). Aging is associated with decreased NAS production, largely resulting from the down-regulation of beta 1 adrenoreceptors that activate serotonin N-acetyltransferase, the enzyme catalyzing formation of NAS from serotonin. NAS exerts antidepressant-like and cognition-enhancing effects. The NAS role in cognition supported by the discovery that scotophobin, decapeptide extracted from brain and associated with cognition improvement, inhibits NAS conversion into melatonin. Furthermore, NAS (and its derivatives) attenuated cognitive impairment induced by cholinergic neurotoxin and protected against beta-amyloid neurotoxicity. Considering that NAS (but not serotonin or melatonin) is a potent agonist to high-affinity BDNF tyrosine kinase (TrkB) receptors, antidepressant and cognition-enhancing effect of NAS might be mediated by activation of TrkB receptors. NAS and TRkB gradually decreased from 1 postnatal week becoming undetectable in the brains of old rats. Additional mechanisms might include non-receptor mediated anti-inflammatory and anti-oxidative effects of NAS. Therapeutic antidepressant and cognition-improving interventions might include administration of NAS and its analogs; inhibition of tryptophan - kynurenine metabolism to increase serotonin availability as a substrate for NAS biosynthesis; up-regulation of NAS formation from serotonin and down-regulation of NAS conversion into melatonin.

Oxenkrug, Gregory; Ratner, Rebbie

2012-01-01

343

Instantánea de nanotecnología  

Cancer.gov

Resumen básico de la nanotecnología, la cual consiste en el diseño y la creación de dispositivos tan pequeños que solo pueden medirse a escala molecular. También se incluye información sobre las investigaciones que realiza el NCI en este campo.

344

Estudio de Exámenes de Detección de Cáncer de Próstata, Pulmón, Colorrectal y Ovarios (PLCO): preguntas y respuestas  

Cancer.gov

El estudio de exámenes de detección PLCO es un estudio a gran escala, aleatorizado, para determinar si el uso de ciertos exámenes selectivos de detección disminuirá el riesgo de morir por esos cuatro tipos de cáncer.

345

Naphthenic acids in athabasca oil sands tailings waters are less biodegradable than commercial naphthenic acids.  

PubMed

Naphthenic acids (NAs) are natural constituents in many petroleum sources, including bitumen in the oil sands of Northern Alberta, Canada. Bitumen extraction processes produce tailings waters that cannot be discharged to the environment because NAs are acutely toxic to aquatic species. However, aerobic biodegradation reduces the toxic character of NAs. In this study, four commercial NAs and the NAs in two oil sands tailings waters were characterized by gas chromatography-mass spectrometry. These NAs were also incubated with microorganisms in the tailings waters under aerobic, laboratory conditions. The NAs in the commercial preparations had lower molecular masses than the NAs in the tailings waters. The commercial NAs were biodegraded within 14 days, but only about 25% of the NAs native to the tailings waters were removed after 40-49 days. These results show that low molecular mass NAs (C < or =17) are more readily biodegraded than high molecular mass NAs (C > or =18). Moreover, the results indicate that biodegradation studies using commercial NAs alone will not accurately reflect the potential biodegradability of NAs in the oil sands tailings waters. PMID:16294878

Scott, Angela C; MacKinnon, Michael D; Fedorak, Phillip M

2005-11-01

346

Datação do disco galáctico pela nucleocosmocronologia do [Th\\/Eu  

Microsoft Academic Search

A nucleocosmocronologia emprega abundâncias de nuclídeos radioativos na datação de escalas de tempo astrofísicas. O 232Th é um nuclídeo radioativo com meia-vida de 14 Gano, enquanto que os dois isótopos mais abundantes do Eu são estáveis. O decaimento radioativo do Th modifica as razões de abundâncias [Th\\/Eu], fornecendo assim um meio de sondar a escala de formação das populações estelares.

E. F. del Peloso; L. da Silva; L. I. Arany-Prado

2003-01-01

347

Deforestation and Biogenic Trace Emissions from Brazilian Cerrado  

NASA Technical Reports Server (NTRS)

The overall goal of NASA's SCAR (Smoke, Cloud and Radiation) Program is to obtain physical and chemical properties of the smoke produced by biomass burning and the effects of the smoke on the earth's radiation balance and climate. It is a joint project with the Brazilian government and their organizations, including INPE (Instituto Nacional Pesquisas Espaciais) who actively participate in all activities. Appropriate estimates of the biomass buming in the tropics is therefore essential to determine its effect on the atmosphere and on climate. The SCAR series of experiments is designed with that purpose. The present study of evaluating the burnt-out areas is to augment the data collected to date to help evaluate the effect of biomass burning.

Sinha, Ravi; Geol, P.

1996-01-01

348

Limitation of fluorescence spectrophotometry in the measurement of naphthenic acids in oil sands process water.  

PubMed

Fluorescence spectrophotometry has been proposed as a quick screening technique for the measurement of naphthenic acids (NAs). To evaluate the feasibility of this application, the fluorescence emission spectra of NAs extracted from three oil sands process water sources were compared with that of commercial NAs. The NAs resulting from the bitumen extraction process cannot be differentiated because of the similarity of the fluorescence spectra. Separation of the fluorescent species in NAs using high performance liquid chromatography with fluorescence detector proved unsuccessful. The acidic fraction of NAs is fluorescent but the basic fraction of NAs is not fluorescent, implying that aromatic acids in NAs give rise to the fluorescent signals. The concentrations of NAs in oil sands process water were measured by Fourier transform infrared spectroscopy (FTIR), fluorescence spectrophotometry and ultra high performance liquid chromatography-time of flight/mass spectrometry (UPLC-TOF/MS). Commercial Merichem and Kodak NAs are the best standards to use when measuring NAs concentration with FTIR and fluorescence spectrophotometry. In addition, the NAs concentrations measured by fluorescence spectrophotometry are about 30 times higher than those measured by FTIR and UPLC-TOF/MS. The findings in this study underscore the limitation of fluorescence spectrophotometry in the measurement of NAs. PMID:23379948

Lu, Weibing; Ewanchuk, Andrea; Perez-Estrada, Leonidas; Sego, Dave; Ulrich, Ania

2013-01-01

349

Determinação de regiões de órbitas diretas estáveis ao redor da Lua  

NASA Astrophysics Data System (ADS)

Neste Trabalho estamos investigando regiões do sistema Terra-Lua que contêm órbitas diretas estáveis ao redor da Lua visando a utilização destas órbitas em futuras missões de veículos espaciais como alternativas de trajetórias com baixo custo de manutenção. Adotando-se o problema restrito de três corpos, Terra-Lua-partícula, a localização e a extensão destas regiões de estabilidade foram investigadas numericamente considerando como estável toda órbita que permanece ao redor a Lua por, no mínimo, 1000 dias com energia de dois corpos da partícula em relação à Lua negativa. A estabilidade de tais regiões está associada a duas famílias de órbitas periódicas simples H1 e H2 e a órbitas quase-periódicas associadas a elas. Uma vez identificadas as regiões de estabilidade passamos a analisá-las introduzindo, paulatinamente, outras interações relevantes ao sistema como as perturbações do Sol (via problema restrito de quatro corpos), das marés, da pressão de radiação e do achatamento terrestre. Os resultados encontrados até o momento mostram que a perturbação do Sol é a única que reduz significativamente o tamanho das regiões de estabilidade. Também estamos investigando o comportamento de tais regiões quando características intrínsecas do sistema como as excentricidades das órbitas da Terra e da Lua e a inclinação da órbita Lua são consideradas. Com este estudo estamos reunindo informações que nos permitirão compreender a evolução das regiões de estabilidade no sistema Terra-Lua, bem como estabelecer parâmetros adequados para a utilização das trajetórias estáveis em futuras missões espaciais. Agradecimentos: Este projeto conta com o apoio do CNPq, da Capes e da Fapesp.

de Melo, C. F.; Winter, O. C.; Vieira Neto, E.

2003-08-01

350

77 FR 47924 - Determinations Concerning Illnesses Discussed in National Academy of Sciences Report: Veterans...  

Federal Register 2010, 2011, 2012, 2013

...including small intestine and anus), hepatobiliary cancers (liver, gallbladder, and...statistically significant increased risk of hepatobiliary cancers in exposed workers. NAS concluded...link the chemicals of interest with hepatobiliary cancers. NAS noted that the...

2012-08-10

351

75 FR 14391 - Diseases Associated With Exposure to Certain Herbicide Agents (Hairy Cell Leukemia and Other...  

Federal Register 2010, 2011, 2012, 2013

...of Sciences (NAS) Institute of Medicine committee report, Veterans and...Exposure to Herbicides, Institute of Medicine (IOM) of the NAS, and other...According to Harrison's Principles of Internal Medicine (Harrison's Online,...

2010-03-25

352

National Airspace System: Transformation Will Require Cultural Change, Balanced Funding Priorities, and Use of All Available Management Tools.  

National Technical Information Service (NTIS)

The National Airspace System (NAS) is a complex network of airports, aircraft, air traffic control (ATC) facilities, employees, and pilots. The aviation industry, which depends on the NAS, contributes about 9 percent to the gross domestic product. The Fed...

2005-01-01

353

National Airspace System. Navigation Operational Concept.  

National Technical Information Service (NTIS)

A requirement for the National Airspace System (NAS) is to provide for navigation, as identified in the NAS System Requirements Specification (NASSRS). The operational concept is one of many high level documents that will, in total, describe the operation...

W. Trent, T. Pickerell, H. Nelson

1991-01-01

354

78 FR 12041 - Information on Surplus Land at Former Naval Air Station, Brunswick, ME  

Federal Register 2010, 2011, 2012, 2013

...additional surplus property at the former Naval Air Station (NAS), Brunswick, ME, in accordance with the Defense Base Closure...of approximately 10 acres of land and facilities at the former NAS Brunswick. The land and facilities were formerly requested...

2013-02-21

355

78 FR 22189 - Establishment of Area Navigation (RNAV) Routes; OR  

Federal Register 2010, 2011, 2012, 2013

...the implementation of RNAV in the National Airspace System (NAS) and provides continued en route navigation guidance in the...enhances safety and efficiency, expands the use of RNAV within the NAS, and provides for continued en route navigation guidance...

2013-04-15

356

21 CFR 520.763c - Dithiazanine iodide and piperazine citrate suspension.  

Code of Federal Regulations, 2013 CFR

...piperazine citrate). (b) Sponsor. See 000010 in § 510.600(c) of this chapter. (c) NAS/NRC status. The conditions of use are NAS/NRC reviewed and found effective. Applications for these uses need not include...

2013-04-01

357

21 CFR 520.1720d - Phenylbutazone gel.  

Code of Federal Regulations, 2013 CFR

...phenylbutazone. (b) Sponsor. See No. 061623 in § 510.600(c) of this chapter. (c) NAS/NRC status. The conditions of use are NAS/NRC reviewed and found effective. Applications for these uses need not include...

2013-04-01

358

41 CFR 102-3.40 - What types of committees or groups are not covered by the Act and this part?  

Code of Federal Regulations, 2013 CFR

...Management part: (a) Committees created by the National Academy of Sciences (NAS) or the National Academy of Public Administration (NAPA). Any committee created by NAS or NAPA in accordance with section 15 of the Act, except as otherwise...

2013-07-01

359

Odor detection thresholds of naphthenic acids from commercial sources and oil sands process-affected water  

Microsoft Academic Search

Naphthenic acids (NAs) occur naturally in various petroleums and in oil sands tailings waters and have been implicated as potential fish tainting compounds. In this study, trained sensory panels and the general population from a university were used to determine the odor detection thresholds of two commercial NAs preparations (Acros and Merichem) and of NAs extracted from an oil sands

Kristyn Edge; Brenda Barona; Rozlyn F. Young; Phillip M. Fedorak; Wendy V. Wismer

2010-01-01

360

76 FR 26290 - Science Advisory Board Staff Office; Notification of a Public Teleconference of the Chartered...  

Federal Register 2010, 2011, 2012, 2013

...EPA's Reanalysis of Key Issues Related to Dioxin Toxicity and Response to NAS Comments...EPA's Reanalysis of Key Issues Related to Dioxin Toxicity and Response to NAS Comments...EPA's Reanalysis of Key Issues Related to Dioxin Toxicity and Response to NAS...

2011-05-06

361

National Airspace System Communications Operational Concept.  

National Technical Information Service (NTIS)

A requirement for the National Airspace System (NAS) is to provide for communications, as identified in the NAS System Requirement Specification, NAS-SR-1000 (NASSRS). This document presents a concept of operation for air-ground, ground-ground communicati...

H. Nelson, T. Pickerell, W. Trent

1991-01-01

362

77 FR 24157 - Proposed Establishment of Area Navigation (RNAV) Routes; Southwestern United States  

Federal Register 2010, 2011, 2012, 2013

...RNAV within the National Airspace System (NAS) and provide substitute [[Page 24158...expand the availability of RNAV within the NAS and provide substitute route segments for...for users, increase the efficiency of the NAS and expand the use of RNAV within the...

2012-04-23

363

Pluralizing the Monoculture  

ERIC Educational Resources Information Center

The National Association of Scholars (NAS) is now entering its twentieth year. The organization has grown over ten-fold since their national launch. When NAS made its debut, today's extensive infrastructure for higher education reform did not yet exist. In this article, the author discusses the contributions of NAS to the academe. The author also…

Balch, Stephen H.

2007-01-01

364

75 FR 8485 - Revocation of Class D and E Airspace; Brunswick, ME  

Federal Register 2010, 2011, 2012, 2013

...the Class D and E Airspace at Brunswick NAS Airport, Brunswick, ME, as the airport...SUPPLEMENTARY INFORMATION: History The Brunswick NAS Airport in Brunswick, ME has closed in...Class D, and E4 airspace for the Brunswick NAS Airport, Brunswick, ME. This rule...

2010-02-25

365

32 CFR 728.33 - Nonavailability statement (DD 1251).  

Code of Federal Regulations, 2010 CFR

... Emergency care claims do not require an NAS; however, the nature of the service...are responsible for determining whether an NAS is necessary in the area of their residence...or traveling. Individuals requiring an NAS because they reside in the inpatient...

2009-07-01

366

76 FR 9400 - Agency Information Collection Activities: Requests for Comments; Clearance of Renewed Approval of...  

Federal Register 2010, 2011, 2012, 2013

...exist within the National Airspace System (NAS). Essential to the assessment is a survey...new hazards have been introduced into the NAS. In addition to on-site visits, the...users of the National Airspace System (NAS). Respondents: 150,607 users of...

2011-02-17

367

75 FR 54942 - Agency Information Collection Activities: Requests for Comments; Clearance of a New Approval of...  

Federal Register 2010, 2011, 2012, 2013

...exist within the National Airspace System (NAS). Essential to the assessment is a survey...new hazards have been introduced into the NAS. In addition to on-site visits, the...users of the National Airspace System (NAS). [[Page 54943

2010-09-09

368

48 CFR 832.111 - Contract clauses for non-commercial purchases.  

Code of Federal Regulations, 2013 CFR

...section entitled âNetwork Analysis System (NAS),â the contracting officer must insert...fixed-price construction contracts (without NAS). When the solicitation or contract...section entitled âNetwork Analysis System (NAS),â the contracting officer must...

2013-10-01

369

Intrinsic Job Satisfaction, Overall Satisfaction, and Intention to Leave the Job among Nursing Assistants in Nursing Homes  

ERIC Educational Resources Information Center

Purpose: We examined predictors of intrinsic job satisfaction, overall satisfaction, and intention to leave the job among nursing assistants (NAs). Design and Methods: The study focused on NAs who worked 30 or more hours per week in a nursing home. Data on 2,146 NAs meeting this criterion came from the 2004 National Nursing Assistant Survey, the…

Decker, Frederic H.; Harris-Kojetin, Lauren D.; Bercovitz, Anita

2009-01-01

370

41 CFR 102-3.185 - What does this subpart require agencies to do?  

Code of Federal Regulations, 2013 CFR

...agency by the National Academy of Sciences (NAS) or the National Academy of Public Administration...Government; and (2) In the case of NAS, the academy certifies that it has complied...grants, and cooperative agreements with NAS or NAPA that are consistent with...

2013-07-01

371

41 CFR 102-3.180 - What does this subpart cover and how does it apply?  

Code of Federal Regulations, 2013 CFR

...agency by the National Academy of Sciences (NAS) or the National Academy of Public Administration...academy. For purposes of this subpart, NAS also includes the National Academy of Engineering...Research Council. Except with respect to NAS committees that were the subject of...

2013-07-01

372

32 CFR 728.33 - Nonavailability statement (DD 1251).  

Code of Federal Regulations, 2010 CFR

... Emergency care claims do not require an NAS; however, the nature of the service...are responsible for determining whether an NAS is necessary in the area of their residence...or traveling. Individuals requiring an NAS because they reside in the inpatient...

2010-07-01

373

The nature of Neptune’s increasing brightness: evidence for a seasonal response ? ? Based on observations made with the NASA\\/ESA Hubble Space Telescope and on observations obtained from the data archive at the Space Telescope Science Institute (STScI), which is operated by the Association of Universities for Research in Astronomy, Inc. under NASA Contract NAS 5-26555. Research supported by grants from STScI and NASA’s Planetary Atmospheres Program  

Microsoft Academic Search

Hubble Space Telescope (HST) observations in August 2002 show that Neptune’s disk-averaged reflectivity increased significantly since 1996, by 3.2 ± 0.3% at 467 nm, 5.6 ± 0.6% at 673 nm, and 40 ± 4% in the 850–1000 nm band, which mainly results from dramatic brightness increases in restricted latitude bands. When 467-nm HST observations from 1994 to 2002 are added

L. A. Sromovsky; P. M. Fry; S. S. Limaye; K. H. Bainesb

2003-01-01

374

Estudo do campo hiperfino magnetico no sitio do (sup 181)Ta nas ligas de Heusler Co(sub 2) Sc Sn, Co(sub 2) Sc Ga e Co(sub 2) Hf Sn. (Study of the hyperfine magnetic field at Ta(sup 181) site in the Heusler Co(sub 2) Sc Sn, Co(sub 2) Sc Ga and Co(sub 2) Hf Sn alloys).  

National Technical Information Service (NTIS)

The hyperfine magnetic fields acting on (sup 181) Ta nuclei at the Sc and Hf sites have been measured in Heusler alloys Co(sub 2) Sc Sn and Co(sub 2) Sc Ga and Co(sub 2) Hf Sn using the Time Differential Perturbed (gamma)-(gamma) Angular Correlation (TDPA...

R. N. Attili

1992-01-01

375

Identification and transcriptional analysis of nitrate assimilation genes in the halophilic archaeon Haloferax mediterranei.  

PubMed

Sequencing a 6,720-bp segment of the extreme halophilic archaeon Haloferax mediterranei genome has revealed the genomic organization of the putative structural genes for nitrate assimilation. We report a gene operon containing nasABC and nasD gene. nasA encodes an assimilatory nitrate reductase, nasB codes for a membrane protein with similarity to the NarK transporter, nasC encodes a protein with similarity to MobA; and nasD codes for an assimilatory ferredoxin-dependent nitrite reductase. Reverse transcription-PCR and primer extension experiments have demonstrated the existence of one polycistronic messenger nasABC and one monocistronic nasD initiated from a different promoter. The gene order and the grouping in two adjacent transcriptional units constitutes a novel organization of nas genes. The promoter regions harbor direct palindromes reminiscent of target sites for binding of a hypotetical regulatory protein(s). Transcription of the nasABC and nasD regions was found to be repressed by the presence of ammonium as nitrogen source. PMID:16182473

Lledó, Belén; Marhuenda-Egea, Frutos C; Martínez-Espinosa, Rosa María; Bonete, María José

2005-11-21

376

Influence of molecular structure on the biodegradability of naphthenic acids.  

PubMed

Large volumes of toxic aqueous tailings containing a complex mixture of naphthenic acids (NAs; CnH2n+ZO2) are produced in northern Alberta by the oil sands industry. Because of their persistence and contribution to toxicity, there is an urgent need to understand the fate of NAs under a variety of remediation scenarios. In a previous study, we developed a highly specific HPLC-high resolution mass spectrometry method for the analysis of NAs. Here we apply this method to determine quantitative structure-persistence relationships and kinetics for commercial NAs and NAs in oil sands process water (OSPW) during aerobic microbial biodegradation. Biodegradation of commercial NAs revealed thatthe mixture contained a substantial labile fraction, which was rapidly biodegraded, and a recalcitrant fraction composed of highly branched compounds. Conversely, NAs in OSPW were predominantly recalcitrant, and degraded slowly by first-order kinetics. Carbon number (n) had little effect on the rate of biodegradation, whereas a general structure-persistence relationship was observed indicating that increased cyclization (Z) decreased the biodegradation rate for NAs in both mixtures. Time to 50% biodegradation ranged from 1 to 8 days among all NAs in the commercial mixture, whereas half-lives for OSPW NAs ranged from 44 to 240 days, likely a result of relatively high alkyl branching among OSPW NAs. It is anticipated that these data will facilitate development of strategic solutions for remediating billions of cubic meters of OSPW stored, or predicted to be generated, in Northern Alberta. PMID:18351107

Han, Xiumei; Scott, Angela C; Fedorak, Phillip M; Bataineh, Mahmoud; Martin, Jonathan W

2008-02-15

377

Current developments in nucleoside/nucleotide analogues for hepatitis B.  

PubMed

There had been remarkable development in nucleos(t)ide analogues (NAs) and evolution in treatment strategies in last 15 years. Currently, there are five NAs available for chronic hepatitis B treatment, namely lamivudine, telbivudine and entecavir (nucleoside analogues), adefovir dipivoxil and tenofovir disoproxil fumarate (nucleotide analogues). The advantages of relatively infrequent side effects and easy administration per oral make NAs popular treatment options. The major drawback of earlier generation NAs is the risk of emergence of drug resistance. Current international guidelines recommend the use of more potent agents with high genetic barriers to resistance including entecavir and tenofovir as first line chronic hepatitis B treatment. However, there is no consensus regarding the subsequent treatment regimens in patients with suboptimal responses to NAs. De novo combination therapy of two NAs, response-guided therapy and roadmap concept in NAs with subsequent switch or add-on therapy can also potentially improve treatment efficacy and avoid resistance. PMID:24787673

Lo, Angeline Oi-Shan; Wong, Grace Lai-Hung

2014-08-01

378

The impact of novel therapeutic agents before and after frontline autologous stem cell transplantation in patients with multiple myeloma  

PubMed Central

Background Novel agents (NAs) such as thalidomide and bortezomib have been administered in combination with autologous stem-cell transplantation (ASCT) to effectively treat multiple myeloma (MM). However, whether NAs perform better as induction treatments prior to transplantation, or as post-transplant maintenance therapies remains unclear. Methods We retrospectively analyzed 106 consecutive patients with MM who underwent ASCT within 1 year of diagnosis as first-line therapy. Results Eighty-seven (82.1%) patients received NAs before ASCT, whereas 68 (64.2%) received NAs after ASCT. NAs were administered to each patient as follows: before ASCT alone (N=29, 27.4%), after ASCT alone (N=10, 9.4%) or both before and after ASCT (N=58, 54.7%). High-quality rates before and after ASCT were significantly higher for patients who received NAs as induction treatment compared to those who did not receive pre-transplant NAs. At a median follow-up of 37.9 months, the 3-year progression-free survival (PFS) and overall survival (OS) rates were 42.8% and 70.2%, respectively. The PFS and OS were significantly higher in patients with NAs as post-transplant maintenance treatment (P=0.03 and P=0.04, respectively), but not in those with NAs as pre-transplant induction treatment. The PFS of patients with NAs before and after ASCT was higher than that of the patients with NAs as induction therapy alone (P=0.05). Age, serum ?2-microglobulin level, complete response after ASCT, and NA use post-ASCT independently predicted survival outcomes. Conclusion These findings suggest that integration of NAs post-ASCT could benefit patients with MM undergoing ASCT. Induction therapy using NAs also improves high-quality response rates before and after ASCT.

Lee, Sung-Eun; Yahng, Seung-Ah; Cho, Byung-Sik; Eom, Ki-Seong; Kim, Yoo-Jin; Kim, Hee-Je; Lee, Seok; Cho, Seok-Goo; Kim, Dong-Wook; Lee, Jong-Wook; Min, Woo-Sung; Park, Chong-Won

2013-01-01

379

The nursing assistants' communication style and the behavioral symptoms of dementia in Korean-American nursing home residents.  

PubMed

Few studies examined the association between communication style and behavioral symptoms of dementia (BSD). The communication style of Nursing Assistants' (NAs), whose ethnic background is different from the residents, may contribute to BSD. The purpose of this study was to explore the relationship between non-Korean NAs' communication style and BSD in Korean-American (KA) nursing home residents with dementia. Twenty eight NAs and 20 KA residents were recruited from an ethno-specific nursing home. Research assistants observed and recorded NAs' communication style and residents' behavior simultaneously during routine care for 3 days. This study shows a trend that NAs' dementia and culturally appropriate communication style influenced the decreased behavioral symptoms. This finding suggests the need for training for NAs in dementia and culturally appropriate communication. PMID:24702713

Kim, Haesook; Woods, Diana Lynn; Mentes, Janet C; Martin, Jennifer L; Moon, Ailee; Phillips, Linda R

2014-01-01

380

Sentinel node biopsy for breast cancer may have little to offer four-node-samplers  

Microsoft Academic Search

The aims of the study were to determine how often four node axillary sampling (4NAS) encompasses the sentinel node (SN) and to compare the relative sensitivity of 4NAS with sentinel node biopsy (SNB) for axillary node staging. 200 patients with breast cancer were preoperatively injected with 27 MBq 99m-Tc-labelled colloid adjacent to the tumour. At operation, standard 4NAS was performed.

R. D. Macmillan; D. Barbera; D. J. Hadjiminas; R. S. Rampaul; A. H. S. Lee; S. E. Pinder; I. O. Ellis; R. W. Blamey; J. G. Geraghty

2001-01-01

381

High Capacity Voice Recorder (HCVR) Operational Test and Evaluation (OT and E)/integration test plan  

NASA Astrophysics Data System (ADS)

This plan addresses the Operational Test and Evaluation (OT&E)/Integration testing of the High Capacity Voice Recorder (HCVR) equipment in the current NAS environment. The approach and concept is to conduct integration tests with appropriate National Airspace System (NAS) subsystem to verify that NAS requirements and HCVR Purchase Description (PD) requirements have been satisfied. This will be accomplished by conducting unit level tests at the FAA Technical Center and extensive integration tests at Seattle Air Route Traffic Control Center (ARTCC).

Bell, Wayne E.; Colon, Andy; Lind, Edward

1992-02-01

382

Variables de personalidad, alteraciones psicopatológicas y trastornos de personalidad en pacientes con dependencia de alcohol en función de la tipología de Cloninger  

Microsoft Academic Search

En este estudio se lleva a cabo una investigación sobre los diferentes tipos de alcohol-dependientes se- gún la tipología de Cloninger en dimensiones de personalidad, características psicopatológicas y tras- tornos de personalidad. La muestra constó de 158 alcohol-dependientes en tratamiento (56 sujetos del tipo I y 102 del tipo II). Se les administraron diversas pruebas de personalidad (la Escala de

Enrique Echeburúa; Ricardo Bravo de Medina; Javier Aizpiri

383

Cambio tecnológico y productividad de las empresas industriales uruguayas  

Microsoft Academic Search

En este trabajo se presentan las estimaciones de una función de costos translogarítmica en base a un modelo de datos panel para la industria uruguaya para 541 empresas entre 1988-1994. Asimismo se presentan las estimaciones para distintos agrupamientos, por tipo de empresa, mercado y división. Para el promedio de la muestra, el efecto neto de la escala y el cambio

Ruben Tansini; Patricia Triunfo

1998-01-01

384

POLÍTICAS PÚBLICAS DE FORMACIÓN PARA EL TRABAJO COMO ESTRATEGIA DE INCLUSIÓN SOCIAL. HISTORIAS DE LA ARGENTINA NEOLIBERAL  

Microsoft Academic Search

Este trabajo resume, por un lado los aportes centrales de una investigación más amplia denominada Políticas Públicas y Formación pa ra el Trabajo en Argentina. Articulaciones de una Política Neoliberal2 , cuyo eje fue e l análisis, desde una perspectiva c rítica, de un Programa focalizado e implementado a escala nacional en la República Argentina - el Proyecto Joven -

Esther Levy

385

El gobierno de la educación en Inglaterra y Perú: una mirada comparada desde la economía política  

Microsoft Academic Search

Durante los últimos treinta años, el gobierno de la educación, como el de otros sectores, ha experimentado cambios importantes que han redefinido las escalas en las que se gobiernan los servicios educativos, así como quiénes son los actores responsables de dichos servicios. Este trabajo explora tales cambios en dos casos particulares, Inglaterra y el Perú, dos contextos cuya poca similitud

María Balarín

2012-01-01

386

Habilidades Sociais e Problemas de Comportamento de Pré- Escolares: Comparando Avaliações de Mães e de Professoras Preschooler's Social Skills and Behavior Problems: Comparison between Mother and Teacher Assessments  

Microsoft Academic Search

Resumo Este estudo comparou avaliações de mães e professoras, sobre habilidades sociais e problemas de comportamento de crianças, identificadas pelas professoras, como tendo problemas de comportamento. Participaram mães e professoras de 24 crianças com problemas de comportamento e 24 crianças indicadas como sendo socialmente habilidosas. Foram utilizados o Questionário de Comportamentos Socialmente Adequados e a Escala Comportamental Infantil, versões para

Alessandra Turini Bolsoni-Silva; Edna Maria Marturano; Verônica Aparecida Pereira; Jair Wagner de Souza Manfrinato

387

TYPE A BEHAVIOUR WITH ERCTA SCALE IN NORMAL SUBJECTS AND CORONARY PATIENTS  

Microsoft Academic Search

This paper presents new research on the Type A behaviour scale ERCTA (Escala Retiro de Patr—n de Conducta Tipo A), developed with a Spanish population. The scale, with eight items, was applied to two groups: normal subjects, and subjects with cardiovascular disorders. We show the validity and reliability of the scale by means of: alpha coefficients, factor analy- sis and

C. Rodríguez Sutil; P. Gil Corbacho; R. Martínez Arias; M. Gonzalez Alvarez; E. Pulido Requero

1998-01-01

388

EFICIÊNCIA PRODUTIVA DE EMPRESAS DA INDÚSTRIA DE ALIMENTOS NO BRASIL Grupo de Pesquisa: Estrutura, Evolução e Dinâmica dos Sistemas Agroalimentares e Cadeias Agroindustriais  

Microsoft Academic Search

Resumo: A indústria de alimentos no Brasil é um setor de g rande importância para a economia brasileira com poucos estudos publicados quanto ao seu desempenho operacional. Este trabalho avalia a eficiência relativa (técnica e de escala) de uma amostra de empresas de diferentes segmentos desta indústria, utilizando-se para tanto o Método DEA. Os segmentos analisados foram: Conglomerados Alimentícios; Óleos

Apresentação Oral-Estrutura; OSCAR TUPY

389

Estudio del NCI revela que la obesidad extrema puede acortar la esperanza de vida hasta en 14 años  

Cancer.gov

Los adultos con obesidad extrema tienen un mayor riesgo de morir a una edad más joven debido al cáncer y a muchas otras causas entre ellas, enfermedades cardíacas, accidentes cerebrovasculares, diabetes y enfermedades del hígado y los riñones, según los resultados de un análisis de datos de 20 estudios a gran escala realizados en personas de tres países.

390

INTEGRACIÓN DE LA DIMENSIÓN AMBIENTAL AL PROCESO DE DESARROLLO DE LAS COMPETENCIAS LABORALES. UNA NECESIDAD EN LA GESTIÓN EMPRESARIAL  

Microsoft Academic Search

Con la finalidad de abordar y analizar los elementos que sustentan la necesidad de integrar la dimensión ambiental al proceso de desarrollo de las competencias laborales, se valora la relación de la especie humana con el medio ambiente a escala mundial, su estado y propósito en Cuba, abordándose la necesidad de desarrollar el Capital Humano dentro de la cultura ambiental

Ana Victoria Nápoles Villa; Clara Marrero Fornaris

2009-01-01

391

The Factor Structure of Preschool Learning Behaviors Scale Scores in Peruvian Children  

ERIC Educational Resources Information Center

The factor structure of the Escala de Conductas de Aprendizaje Preescolar (ECAP), a Spanish translation of the Preschool Learning Behaviors Scale (PLBS), was examined in this study. Children aged 2 to 6 years (N = 328) enrolled in public and private preschools in the Republic of Peru were rated by classroom teachers on the frequency of observable,…

Hahn, Kathryn R.; Schaefer, Barbara A.; Merino, Cesar; Worrell, Frank C.

2009-01-01

392

Arabidopsis thaliana nicotianamine synthase 4 is required for proper response to iron deficiency and to cadmium exposure.  

PubMed

The nicotianamine synthase (NAS) enzymes catalyze the formation of nicotianamine (NA), a non-proteinogenic amino acid involved in iron homeostasis. We undertook the functional characterization of AtNAS4, the fourth member of the Arabidopsis thaliana NAS gene family. A mutant carrying a T-DNA insertion in AtNAS4 (atnas4), as well as lines overexpressing AtNAS4 both in the atnas4 and the wild-type genetic backgrounds, were used to decipher the role of AtNAS4 in NA synthesis, iron homeostasis and the plant response to iron deficiency or cadmium supply. We showed that AtNAS4 is an important source for NA. Whereas atnas4 had normal growth in iron-sufficient medium, it displayed a reduced accumulation of ferritins and exhibited a hypersensitivity to iron deficiency. This phenotype was rescued in the complemented lines. Under iron deficiency, atnas4 displayed a lower expression of the iron uptake-related genes IRT1 and FRO2 as well as a reduced ferric reductase activity. Atnas4 plants also showed an enhanced sensitivity to cadmium while the transgenic plants overexpressing AtNAS4 were more tolerant. Collectively, our data, together with recent studies, support the hypothesis that AtNAS4 displays an important role in iron distribution and is required for proper response to iron deficiency and to cadmium supply. PMID:23759098

Koen, Emmanuel; Besson-Bard, Angélique; Duc, Céline; Astier, Jérémy; Gravot, Antoine; Richaud, Pierre; Lamotte, Olivier; Boucherez, Jossia; Gaymard, Frédéric; Wendehenne, David

2013-08-01

393

Home Availability and the Impact of Weekly Stressful Events Are Associated with Fruit and Vegetable Intake among African American and Hispanic/Latina Women. — Measures of the Food Environment  

Cancer.gov

Background. Mediating and moderating variables may interfere with the association between neighborhood availability of grocery stores (NAG) and supermarkets (NAS) and fruit and vegetable (FV) intake. Objective.

394

Otimização de procedimento de manobra para indução de reentrada de um satélite retornável  

NASA Astrophysics Data System (ADS)

Veículos espaciais que retornam à Terra passam por regimes de velocidade e condições de vôo distintos. Estas diferenças dificultam sua concepção aerodinâmica e o planejamento de seu retorno. A partir de uma proposta de um veículo orbital retornável (satélite SARA, em desenvolvimento no IAE/CTA) para realização de experimentos científicos e tecnológicos em ambiente de baixa gravidade, surge a necessidade de realizarem-se estudos considerando-se os aspectos relativos à sua aerodinâmica. Após o lançamento, o veículo deve permanecer em órbita pelo tempo necessário para a condução de experimentos, sendo depois direcionado à Terra e recuperado em solo. A concepção aerodinâmica é de importância para o vôo em suas diversas fases e deve considerar aspectos relativos à estabilização Aerodinâmica e ao arrasto atmosférico, sendo este último de importância crucial na análise do aquecimento a ser enfrentado. A manobra de retorno inclui considerações sobre as condições atmosféricas e dinâmica de reentrada, devendo ser calculada de forma mais precisa possível. O trabalho proposto avalia estudos da dinâmica de vôo de um satélite recuperável considerando aspectos relativos à determinação orbital com GPS, técnica utilizada com sucesso na CONAE, e seu comportamento aerodinâmico em vôo balístico de retorno, com ênfase em sua fase de reentrada atmosférica. Busca-se otimizar a manobra de reentrada de tal forma que a utilização do sistema GPS garanta minimizar a área de impacto com o solo.

Schulz, W.; Suarez, M.

2003-08-01

395

Controle orbital de satélites artificiais com propulsão e uso de gravidade lunar  

NASA Astrophysics Data System (ADS)

A redução do custo de combustível de uma manobra é atualmente a grande prioridade de todos os programas espaciais existentes no mundo. As manobras assistidas pela gravidade são uma ótima forma de se contornar o problema pois proporcionam economias com vasto impacto no custo final da missão. Neste trabalho é feito um estudo particular do controle orbital de um satélite artificial da Terra usando a gravidade da Lua. O objetivo é estudar uma técnica econômica para uma mudança de plano de um satélite que está em órbita em volta da Terra. A idéia principal desta abordagem é enviar primeiramente o veículo espacial em direção à Lua usando uma manobra mono-impulsiva para que assim o campo gravitacional da Lua possa fazer a mudança de plano desejada (sem custo de combustível) e só então retornar o veículo aos valores iniciais de semi-eixo e excentricidade usando uma manobra bi-impulsiva tipo Hohmann. Para tanto, é assumido que a espaçonave inicia em uma órbita circular coplanar à órbita da lua em torno da Terra e a meta é colocá-la em uma órbita similar que difere da órbita inicial somente pela inclinação. São usadas equações analíticas baseadas na abordagem Patched Conics para se calcular a variação na velocidade, momento angular, energia e inclinação do veículo espacial que realiza esta manobra. Várias simulações são feitas para se avaliar as economias de combustível envolvidas.

Torres, K. S.; de Almeida Prado, A. F. B.

2003-08-01

396

Genotoxic potential of several naphthenic acids and a synthetic oil sands process-affected water in rainbow trout (Oncorhynchus mykiss).  

PubMed

The exploitation of oil sands has raised major environmental concerns, particularly regarding the presence of high concentration in contaminants such as polycyclic aromatic hydrocarbons (PAHs) and naphthenic acids (NAs) in oil sands process-affected water (OSPW). The purpose of this study was, first to evaluate the genotoxic impact of OSPW-related compounds such as NAs and PAHs in a salmonid species and secondly to assess if OSPW exposure leads to genotoxicity. For this purpose, rainbow trout hepatocytes were exposed in vitro to environmentally relevant concentrations of synthetic NAs, naphtalene, benzo(a)pyrene, and extracts of synthetic OSPW (generated by a laboratory bitumen extraction) and of oil sands leaching water (OSLW, mimicking leaching of oil sands in river water). Primary DNA damage was assessed by the formamidopyrimidine-DNA glycolyase (Fpg)-modified comet assay. Genotoxicity was observed in hepatocytes exposed to several NAs, mixture of them, OSPW and OSLW extracts. The chemical structure of NAs influences the genotoxicity potential: among the NAs tested, the most cyclic NA was the most genotoxic. It also appears that genotoxicity was more marked for OSPW than for OSLW. Because exposure to OSPW led to oxidative DNA damage, while after exposure to several NAs, these types of DNA damage were limited, the NAs tested in this study could not be qualified as the only major contaminants responsible for OSPW genotoxicity. Notwithstanding, it should be noteworthy that exposure to NAs resulted in genotoxic impact at concentrations lower than those documented by literature for fresh OSPW. Further research is needed to explore the relationships between the chemical structure of NAs and their genotoxicity in the light of the distribution of NAs in fresh OSPW samples as well as in surface waters. PMID:24799193

Lacaze, E; Devaux, A; Bruneau, A; Bony, S; Sherry, J; Gagné, F

2014-07-01

397

Differences in phytotoxicity and dissipation between ionized and nonionized oil sands naphthenic acids in wetland plants.  

PubMed

Naphthenic acids (NAs) are composed of alkyl-substituted acyclic and cycloaliphatic carboxylic acids and, because they are acutely toxic to fish, are of toxicological concern. During the caustic hot-water extraction of oil from the bitumen in oil sands deposits, NAs become concentrated in the resulting tailings pond water. The present study investigated if dissipation of NAs occurs in the presence of hydroponically grown emergent macrophytes (Typha latifolia, Phragmites australis, and Scirpus acutus) to determine the potential for phytoremediation of these compounds. Plants were grown with oil sands NAs (pKa approximately 5-6) in medium at pH 7.8 (predominantly ionized NAs) and pH 5.0 (predominantly nonionized NAs) to determine if, by altering their chemical form, NAs may be more accessible to plants and, thus, undergo increased dissipation. Whereas the oil sands NA mixture in its nonionized form was more toxic to wetland plants than its ionized form, neither form appeared to be sequestered by wetland plants. The present study demonstrated that plants may selectively enhance the dissipation of individual nonionized NA compounds, which contributes to toxicity reduction but does not translate into detectable total NA dissipation within experimental error and natural variation. Plants were able to reduce the toxicity of a NA system over 30 d, increasing the median lethal concentration (LC50; % of hydroponic solution) of the medium for Daphnia magna by 23.3% +/- 8.1% (mean +/- standard error; nonionized NAs) and 37.0% +/- 2.7% (ionized NAs) as determined by acute toxicity bioassays. This reduction in toxicity was 7.3% +/- 2.6% (nonionized NAs) and 45.0% +/- 6.8% (ionized NAs) greater than that in unplanted systems. PMID:19469588

Armstrong, Sarah A; Headley, John V; Peru, Kerry M; Germida, James J

2009-10-01

398

Naphthenic acids degradation and toxicity mitigation in tailings wastewater systems and aquatic environments: a review.  

PubMed

Naphthenic acids, NAs (classical formula C(n)H(2n+z)O(2), where n is the carbon numbers, z represents zero or negative even integers), found in oil sands process waters (OSPWs), are toxic to aquatic environments depending upon several factors such as pH, salinity, molecular size and chemical structure of NAs. Among various available methods, biodegradation seems to be generally the most cost-effective method for decreasing concentrations of NAs (n ? 21) and reducing their associated toxicity in OSPW, however the mechanism by which the biodegradation of NAs occurs are poorly understood. Ozonation is superior over biodegradation in decreasing higher molecular weight alkyl branched NAs (preferentially, n ? 22, -6 ? z ? -12) as well as enabling accelerated biodegradation and reducing toxicity. Photolysis (UV at 254 nm) is effective in cleaving higher molecular weight NAs into smaller fragments that will be easier for microorganisms to degrade, whereas photocatalysis can metabolize selective NAs (0 ? z ? -6) efficiently and minimize their associated toxicity. Phytoremediation is applicable for metabolizing specific NAs (O(2), O(3), O(4), and O(5) species) and minimizing their associated toxicities. Petroleum coke (PC) adsorption is effective in reducing the more structurally complex NAs (preferentially 12 ? n ? 18 and z = -10, -12) and their toxicity in OSPWs, depending upon the PC content, pH and temperature. Several factors have influence on the degradation of NAs in OSPWs and aquatic environments, which include molecular mass and chemical structure of NAs, sediment structure, temperature, pH, dissolved oxygen, nutrients, and bacteria types. PMID:22217078

Kannel, Prakash R; Gan, Thian Y

2012-01-01

399

Estimating naphthenic acids concentrations in laboratory-exposed fish and in fish from the wild.  

PubMed

Naphthenic acids (NAs) are the most water-soluble organic components found in the Athabasca oil sands in Alberta, Canada, and these acids are released into aqueous tailing waters as a result of bitumen extraction. Although the toxicity of NAs to fish is well known, there has been no method available to estimate NAs concentrations in fish. This paper describes a newly developed analytical method using single ion monitoring gas chromatography-mass spectrometry (GC-MS) to measure NAs in fish, down to concentrations of approximately 0.1mgkg(-1) of fish flesh. This method was used to measure the uptake and depuration of commercial NAs in laboratory experiments. Exposure of rainbow trout (Oncorhynchus mykiss) to 3mg NAsl(-1) for 9d gave a bioconcentration factor of approximately 2 at pH 8.2. Within 1d after the fish were transferred to NAs-free water, about 95% of the NAs were depurated. In addition, the analytical method was used to determine if NAs were present in four species of wild fish - northern pike (Esox lucius), lake whitefish (Coregonus clupeaformis), white sucker (Catostomus commersoni), walleye (Sander vitreus) - collected from near the oil sands. Flesh samples from 23 wild fish were analyzed, and 18 of these had no detectable NAs. Four fish (one of each species) contained NAs at concentrations from 0.2 to 2.8mgkg(-1). The GC-MS results from one wild fish presented a unique problem. However, with additional work it was concluded that the NAs concentration in this fish was <0.1mgkg(-1). PMID:18667226

Young, Rozlyn F; Wismer, Wendy V; Fedorak, Phillip M

2008-09-01

400

Iron fortification of rice seeds through activation of the nicotianamine synthase gene  

PubMed Central

The most widespread dietary problem in the world is mineral deficiency. We used the nicotianamine synthase (NAS) gene to increase mineral contents in rice grains. Nicotianamine (NA) is a chelator of metals and a key component of metal homeostasis. We isolated activation-tagged mutant lines in which expression of a rice NAS gene, OsNAS3, was increased by introducing 35S enhancer elements. Shoots and roots of the OsNAS3 activation-tagged plants (OsNAS3-D1) accumulated more Fe and Zn. Seeds from our OsNAS3-D1 plants grown on a paddy field contained elevated amounts of Fe (2.9-fold), Zn (2.2-fold), and Cu (1.7-fold). The NA level was increased 9.6-fold in OsNAS3-D1 seeds. Analysis by size exclusion chromatography coupled with inductively coupled plasma mass spectroscopy showed that WT and OsNAS3-D1 seeds contained equal amounts of Fe bound to IP6, whereas OsNAS3-D1 had 7-fold more Fe bound to a low molecular mass, which was likely NA. Furthermore, this activation led to increased tolerance to Fe and Zn deficiencies and to excess metal (Zn, Cu, and Ni) toxicities. In contrast, disruption of OsNAS3 caused an opposite phenotype. To test the bioavailability of Fe, we fed anemic mice with either engineered or WT seeds for 4 weeks and measured their concentrations of hemoglobin and hematocrit. Mice fed with engineered seeds recovered to normal levels of hemoglobin and hematocrit within 2 weeks, whereas those that ate WT seeds remained anemic. Our results suggest that an increase in bioavailable mineral content in rice grains can be achieved by enhancing NAS expression.

Lee, Sichul; Jeon, Un Sil; Lee, Seung Jin; Kim, Yoon-Keun; Persson, Daniel Pergament; Husted, S?ren; Schj?rring, Jan K.; Kakei, Yusuke; Masuda, Hiroshi; Nishizawa, Naoko K.; An, Gynheung

2009-01-01

401

Toxicity assessment of collected fractions from an extracted naphthenic acid mixture.  

PubMed

Recent expansion within the oil sands industry of the Athabasca Basin of Alberta, Canada has led to increased concern regarding process-affected wastewaters produced during bitumen extraction. Naphthenic acids (NAs) have been identified as the primary toxic constituents of oil sands process-affected waters (OSPW) and studies have shown that with time, microbial degradation of lower molecular weight NAs has led to a decrease in observed toxicity. As earlier studies identified the need for an "unequivocal demonstration" of lower molecular weight NAs being the primary contributors to mixture toxicity, a study was initiated to fractionate an extracted NA mixture by molecular weight and to assess each fraction's toxicity. Successful molecular weight fractionation of a methylated NA mixture was achieved using a Kugelrohr distillation apparatus, in which fractions collected at higher boiling points contained NAs with greater total carbon content as well as greater degree of cyclicity. Assays with Vibrio fischeri bioluminescence (via Microtox assay) revealed that the lowest molecular weight NAs collected had higher potency (EC50: 41.9+/-2.8 mg l(-1)) than the highest molecular weight NAs collected (EC50: 64.9+/-7.4 mg l(-1)). Although these results support field observations of microbial degradation of low molecular weight NAs decreasing OSPW toxicity, it is not clear why larger NAs, given their greater hydrophobicity, would be less toxic. PMID:18555508

Frank, Richard A; Kavanagh, Richard; Kent Burnison, B; Arsenault, Gilles; Headley, John V; Peru, Kerry M; Van Der Kraak, Glen; Solomon, Keith R

2008-07-01

402

Naphthenic acid biodegradation by the unicellular alga Dunaliella tertiolecta.  

PubMed

Naphthenic acids (NAs) are a major contributor to toxicity in tailings waste generated from bitumen production in the Athabasca Oil Sands region. While investigations have shown that bacteria can biodegrade NAs and reduce tailings toxicity, the potential of algae to biodegrade NAs and the biochemical mechanisms involved remain poorly understood. Here, we discovered that the marine alga Dunaliella tertiolecta is able to tolerate five model NAs (cyclohexanecarboxylic acid, cyclohexaneacetic acid, cyclohexanepropionic acid, cyclohexanebutyric acid and 1,2,3,4-tetrahydro-2-naphthoic acid) at 300mgL(-1), a level which exceeds that of any single or combination of NAs typically found in tailings ponds. Moreover, we show that D. tertiolecta can metabolize four of the model NAs. Analysis of NA-amended cultures of D. tertiolecta via low resolution gas chromatography-mass spectrometry allowed us to quantify decreasing NA levels, identify metabolites, and formulate putative mechanisms of biodegradation. Degradation of cyclohexanebutyric acid and cyclohexanepropionic acid proceeded via ?-oxidation and resulted in the transient accumulation of cyclohexaneacetic acid and cyclohexanecarboxylic acid, respectively. Cyclohexanecarboxylic acid was metabolized via 1-cyclohexenecarboxylic acid suggesting that further degradation may occur by step-wise ?-oxidation. When D. tertiolecta was inoculated in the presence of oil sands tailings water from the Athabasca region, biodegradation of single-ring NAs was observed relative to controls. This result corroborates the trend we observed with the single-ring model NAs. PMID:21459409

Quesnel, Dean M; Bhaskar, Iyswarya M; Gieg, Lisa M; Chua, Gordon

2011-07-01

403

New American Schools after Six Years.  

ERIC Educational Resources Information Center

This book describes the evolution of New American Schools (NAS) and its strategy for reform during its first 6 years of operation. After a short introduction in chapter 1, chapter 2 outlines the potential contribution of school designs and design-based assistance to education reform, focusing on the nature of NAS designs, the character of…

Glennan, Thomas K., Jr.

404

Spiritual Wellness as an Issue in Navy Education and Training: A Literature Review.  

National Technical Information Service (NTIS)

This literature review was conducted as part of a development research project for a poster presentation on Religion and Health for the NAS Whiting Field Health Fair in May 1996. This presentation was prepared by the NAS Whiting Field chaplains. In conduc...

J. C. Duncan

1996-01-01

405

SOBRE O PROCESSO DE MEDIAÇÃO SOCIAL NOS PROJETOS DE DESENVOLVIMENTO: UMA REFLEXÃO TEÓRICA  

Microsoft Academic Search

A mediação social é um tema que nos últimos anos vem ganhando espaço nas discussões sobre o desenvolvimento rural, mais especificamente, nas questões referentes à intervenção para o desenvolvimento. Este processo compreende uma relação que se apresenta como uma “via de mão dupla”, ou seja, a via representa a relação, uma das mãos é os mediadores, e a outra é

Cidonea Machado Deponti; Jalcione Almeida

2008-01-01

406

An Analysis of the Effects of Net-Centric Operations Using Multi-Agent Adaptive Behavior  

ERIC Educational Resources Information Center

The National Airspace System (NAS) is a resource managed in the public good. Equity in NAS access, and use for private, commercial and government purposes is coordinated by regulations and made possible by procedures, and technology. Researchers have documented scenarios in which the introduction of new concepts-of-operations and technologies has…

Calderon-Meza, Guillermo

2011-01-01

407

Shifts in root-associated microbial communities of Typha latifolia growing in naphthenic acids and relationship to plant health.  

PubMed

Naphthenic acids (NAs) are a complex mixture of organic acid compounds released during the extraction of crude oil from oil sands operations. The accumulation of toxic NAs in tailings pond water (TPW) is of significant environmental concern, and phytoremediation using constructed wetlands is one remediation option being assessed. Since root-associated microorganisms are an important factor during phytoremediation of organic compounds, this study investigated the impact of NAs on the microbial communities associated with the macrophyte Typha latifolia (cattail). Denaturing gradient gel electrophoresis revealed that the impact of NAs on microbial communities was niche dependent, with endophytic communities being the most stable and bulk water communities being the least stable. The type of NA used was significant to microbial response, with commercial NAs causing greater adverse changes than TPW NAs. In general, plant beneficial bacteria such as diazotrophs were favoured in cattails grown in TPW NAs, while potentially deleterious bacteria such as denitrifying Dechlorospirillum species increased in commercial NA treatments. These findings suggest that NAs may affect plant health by impacting root-associated microbial communities. A better understanding of these impacts may allow researchers to optimize those microbial communities that support plant health, and thus further optimize wetland treatment systems. PMID:21166345

Phillips, Lori A; Armstrong, Sarah A; Headley, John V; Greer, Charles W; Germida, James J

2010-01-01

408

Shifts in Root-Associated Microbial Communities of Typha Latifolia Growing in Naphthenic Acids and Relationship to Plant Health  

Microsoft Academic Search

Naphthenic acids (NAs) are a complex mixture of organic acid compounds released during the extraction of crude oil from oil sands operations. The accumulation of toxic NAs in tailings pond water (TPW) is of significant environmental concern, and phytoremediation using constructed wetlands is one remediation option being assessed. Since root-associated microorganisms are an important factor during phytoremediation of organic compounds,

Lori A. Phillips; Sarah A. Armstrong; John V. Headley; Charles W. Greer; James J. Germida

2010-01-01

409

Decisionmaking, Transitions, and Resilient Futures  

SciTech Connect

The article describes the focus of research in the social sciences on environmental change, describing studies on adaptation and mitigation. It is the first of 5 articles in the NAS quarterly journal IS&T on the occasion of the launch of a new Board at the NAS chaired by the author.

Moss, Richard H.; Lane, Meredith A.

2012-08-01

410

GUIDANCE ON IDENTIFYING THE APPROPRIATE AGE GROUPS FOR ASSESSING CHILDHOOD EXPOSURE AND RISK  

EPA Science Inventory

The 1993 National Academy of Sciences (NAS) report "Pesticides in the Diets of Infants and Children" highlights important differences between children and adults with respect to risks posed by pesticides. Some of the principles in the NAS report provided the foundation for the Fo...

411

Effects of exposure to naphthenic acids in tree swallows (Tachycineta bicolor) on the Athabasca oil sands, Alberta, Canada.  

PubMed

Naphthenic acids (NAs) are a group of carboxylic acids that are of particular concern to the steadily growing oil sands mining industry of Alberta, Canada, because they become highly concentrated in the water used for oil sands extraction and are toxic to aquatic biota and mammals. Upon mine closure, vast amounts of process-affected water will need to be reclaimed and proven safe for wildlife colonizing reclaimed areas. The effects of exposure to NAs have not been investigated in avian species. To address this void, tree swallow (Tachycineta bicolor) nestlings were dosed with NAs while being reared normally by their free-ranging parents on a site in the vicinity of the oil sands. Nestlings received 1.5 mg NAs/day (approximately 0.075 g/kg body mass) from d 7 to d 13 of age, which represented a 10-fold "worst exposure" scenario. Nestling growth, hematocrit, blood biochemistry, organ weights, and ethoxyresorufin O-deethylase (EROD) activity were unaffected by NAs. The only change detected on histopathological evaluation of major organs was an increase in extramedullary erythropoiesis in the liver. These findings indicate that nestling tree swallows can successfully tolerate short-term exposures to environmentally realistic concentrations of NAs. However, this study did not investigate the chronic or reproductive toxicity of NAs. More research needs to be conducted to complete this initial assessment, to determine environmental risks on reclaimed areas where birds will be breeding and where their exposure to NAs could extend for several weeks. PMID:17573632

Gentes, Marie-Line; Waldner, Cheryl; Papp, Zsuzsanna; Smits, Judit E G

2007-07-01

412

Electrodeposition of silver nanoparticle arrays on ITO coated glass and their application as reproducible surface-enhanced Raman scattering substrate  

NASA Astrophysics Data System (ADS)

In this paper, a double-potentiostatic method is used for preparation of highly efficient and uniform surface-enhanced Raman scattering (SERS) substrate. The method takes advantage of the quick nucleation and slow growth process, yielding silver nanoparticle arrays (NAs) containing large amount of hot spots, which bring about these dense silver NAs for reproducible SERS application.

Bian, Jun-Cao; Li, Zhe; Chen, Zhong-Dong; He, Hai-Yan; Zhang, Xi-Wen; Li, Xiang; Han, Gao-Rong

2011-12-01

413

Electrodeposition of silver nanoparticle arrays on ITO coated glass and their application as reproducible surface-enhanced Raman scattering substrate  

Microsoft Academic Search

In this paper, a double-potentiostatic method is used for preparation of highly efficient and uniform surface-enhanced Raman scattering (SERS) substrate. The method takes advantage of the quick nucleation and slow growth process, yielding silver nanoparticle arrays (NAs) containing large amount of hot spots, which bring about these dense silver NAs for reproducible SERS application.

Jun-Cao Bian; Zhe Li; Zhong-Dong Chen; Hai-Yan He; Xi-Wen Zhang; Xiang Li; Gao-Rong Han

414

Reducing Maternal and Neonatal Mortality in Indonesia: Saving Lives, Saving the Future.  

National Technical Information Service (NTIS)

The idea for a joint study by the U.S. National Academy of Sciences (NAS) and the Indonesian Academy of Sciences (AIPI) emerged from a series of discussions held in 2010 between Sangkot Marzuki, president of AIPI, and Bruce Alberts, former NAS president, ...

2013-01-01

415

Relationship between Weather, Traffic and Delay Based on Empirical Methods  

NASA Technical Reports Server (NTRS)

The steady rise in demand for air transportation over the years has put much emphasis on the need for sophisticated air traffic flow management (TFM) within the National Airspace System (NAS). The NAS refers to hardware, software and people, including runways, radars, networks, FAA, airlines, etc., involved in air traffic management (ATM) in the US. One of the metrics that has been used to assess the performance of NAS is the actual delays provided through FAA's Air Traffic Operations Network (OPSNET). The OPSNET delay data includes those reportable delays, i.e. delays of 15 minutes or more experienced by Instrument Flight Rule (IFR) flights, submitted by the FAA facilities. These OPSNET delays are caused by the application of TFM initiatives in response to, for instance, weather conditions, increased traffic volume, equipment outages, airline operations, and runway conditions. TFM initiatives such as, ground stops, ground delay programs, rerouting, airborne holding, and miles-in-trail restrictions, are actions which are needed to control the air traffic demand to mitigate the demand-capacity imbalance due to the reduction in capacity. Consequently, TFM initiatives result in NAS delays. Of all the causes, weather has been identified as the most important causal factor for NAS delays. Therefore, in order to accurately assess the NAS performance, it has become necessary to create a baseline for NAS performance and establish a model which characterizes the relation between weather and NAS delays.

Sridhar, Banavar; Swei, Sean S. M.

2006-01-01

416

Chief of Naval Air Training Resource Planning System (RPS).  

ERIC Educational Resources Information Center

The Resource Planning System (RPS) provides the Chief of Naval Air Training (CNATRA) with the capability to determine the resources required to produce a specified number of Naval Aviators and Naval Flight Officers (NAs/NFOs) quickly and efficiently. The training of NAs and NFOs is extremely time consuming and complex. It requires extensive…

Hodak, Gary W.; And Others

417

Bold Plans for School Restructuring: The New American Schools Designs.  

ERIC Educational Resources Information Center

In 1991, the New American Schools (NAS) Development Corporation was founded by a group of business and foundation leaders interested in investing in innovative designs for school transformation. This book describes the first 3 years of development and evaluation of 9 NAS whole-school restructuring designs. The designs were very diverse, as were…

Stringfield, Sam, Ed.; Ross, Steven, M., Ed.; Smith, Lana, Ed.

418

Improving Aircraft Refueling Procedures at Naval Air Station Oceana.  

National Technical Information Service (NTIS)

This thesis seeks to improve aircraft refueling at Naval Air Station (NAS) Oceana, VA, using aircraft waiting time for fuel as a measure of performance. We develop a computer-assisted discrete-event simulation to model refueling at NAS Oceana using airfie...

M. T. Geiser

2012-01-01

419

Impositive Speech Acts in Northern Andean Spanish: A Pragmatic Description.  

ERIC Educational Resources Information Center

Northern Andean Spanish (NAS) possesses a complex system of structures used in impositive speech. NAS speakers choose from several grammatical possibilities when asking their interlocutor to act. This article summarizes the grammatical possibilities and explains how the different forms are used to indicate different levels of politeness. (15…

Bustamante-Lopez, Isabel; Nina-Murcia, Mercedes

1995-01-01

420

The Future of the National Association of Scholars  

ERIC Educational Resources Information Center

The National Association of Scholars (NAS) today is focused more than ever on public controversies and on public tools of communication. Where once NAS members were primarily concerned with debates within the academy, now they are equally concerned with debates about the academy. If the topics they address have changed, so too have the means by…

Wood, Peter

2012-01-01

421

77 FR 71493 - Amendment of VOR Federal Airway V-8 in the Vicinity of Rifle, CO  

Federal Register 2010, 2011, 2012, 2013

...ensure the safety and efficiency of the National Airspace System (NAS). DATES: Effective date 0901 UTC December 3, 2012. The Director...authority as it amends an existing VOR Federal airway within the NAS. Environmental Review The FAA has determined that this...

2012-12-03

422

21 CFR 520.2325b - Sulfaquinoxaline drench.  

Code of Federal Regulations, 2013 CFR

...Sponsor. See No. 050749 in § 510.600(c) of this chapter. (d) NAS/NRC status. The conditions of use specified in this section have been reviewed by NAS/NRC and are found effective. Applications for these uses need not...

2013-04-01

423

"What Does Bowdoin Teach"? A Dialogue between Wood and Klingenstein  

ERIC Educational Resources Information Center

This article is an exchange of ideas between Peter Wood, President of the National Association of Scholars (NAS), and Tom Klingerstein, Chairman of the Claremont Institute and NAS Board Director, on the study "What Does Bowdoin Teach? How a Contemporary Liberal Arts College Shapes Students" (by Peter Wood and Michael Toscano). This…

Wood, Peter; Klingenstein, Tom

2013-01-01

424

Fighting the "Damnable Triumph" of Feminism: Battles between Teachers' Unions in Interwar Britain  

ERIC Educational Resources Information Center

The interwar decades saw a bitter recruiting war between the NUT (National Union of Teachers), the National Union of Women Teachers (NUWT), and the National Association of Schoolmasters (NAS), which like the NUWT broke away from the NUT in the early 1920s. The NAS opposed the NUT's official policy shift to support equal pay for male and female…

Wilson, Dolly Smith

2007-01-01

425

77 FR 35618 - Establishment of Area Navigation (RNAV) Routes; Southwestern United States  

Federal Register 2010, 2011, 2012, 2013

...the availability of RNAV within the National Airspace System (NAS) and provide substitute route segments for portions of VOR Federal...NM. The routes expand the availability of RNAV within the NAS and provides substitute route segments for portions of VOR...

2012-06-14

426

MODEL SIMULATION STUDIES OF SCALE-DEPENDENT GAIN IN STREAM NUTRIENT ASSIMILATIVE CAPACITY RESULTING FROM IMPROVING NUTRIENT RETENTION METRICS  

EPA Science Inventory

Considering the difficulty in measuring restoration success for nonpoint source pollutants, nutrient assimilative capacity (NAS) offers an attractive systems-based metric. Here NAS was defined using an impulse-response model of nitrate fate and transport. Eleven parameters were e...

427

76 FR 2800 - Amendment of VOR Federal Airways V-2 and V-21; Hawaii  

Federal Register 2010, 2011, 2012, 2013

...areas that have been removed from the National Airspace System (NAS). DATES: Effective date 0901 UTC, March 10, 2011. The Director...contained exclusions to restricted airspace that was removed from the NAS several years ago. Accordingly, since this is an...

2011-01-18

428

21 CFR 520.1720b - Phenylbutazone granules.  

Code of Federal Regulations, 2013 CFR

...See 000061 in § 510.600(c) for 8-gram package, see 059320 for 1-gram package. (c) NAS/NRC status. The conditions of use have been NAS/NRC reviewed and found effective. NADA's for approval of drugs for these conditions...

2013-04-01

429

75 FR 57848 - Revocation of Class E Airspace, Brunswick, ME; and Establishment of Class E Airspace, Wiscasset, ME  

Federal Register 2010, 2011, 2012, 2013

...SUMMARY: This action removes Class E Airspace at Brunswick NAS, Brunswick, ME, as the airport has closed and the associated...14 CFR) part 71 removes the Class E airspace at Brunswick NAS, Brunswick, ME to reflect the closing of the airport and...

2010-09-23

430

WATER IMPLICATIONS OF BIOFUELS PRODUCTION  

EPA Science Inventory

Presentation requested by the National Academy of Science (NAS) for a Colloquium on Water Quality Implications of Biofuels Production, to be held at the NAS in Washington, D.C. on July 12, 2007. This presentation will address the influence of ethanol on hydrocarbon plumes and th...

431

Making the Case for New Research to Support the Integration of Small Unmanned Aircraft Systems into the National Airspace System  

NASA Technical Reports Server (NTRS)

This paper describes the current state of sUAS regulation, their technical capabilities and the latest technologies that will allow for sUAS NAS integration. The research that is needed to demonstrate sUAS NAS integration capability is identified, and recommendations for conducting this necessary research are suggested.

McAdaragh, Raymon M.; Comstock, James R., Jr.; Ghatas, Rania W.; Burdette, Daniel W.; Trujillo, Anna C.

2014-01-01

432

Monitoring the Progress of New American Schools: A Description of Implementing Schools in a Longitudinal Sample.  

ERIC Educational Resources Information Center

A private, nonprofit corporation, New American Schools (NAS) funds the development of designs aimed at transforming entire schools at the elementary and secondary levels. This report describes a large number of NAS sites in their early implementation stages. The report is the first in a series that monitors a longitudinal sample of schools…

Berends, Mark; Heilbrunn, Jodi; McKelvey, Christopher; Sullivan, Thomas

433

Innovation on Energy Power Technology (7)Development and Practical Application of Sodium-Sulfur Battery for Electric Energy Storage System  

Microsoft Academic Search

Sodium-Sulfur battery (NAS battery), which has more than 3 times of energy density compared with the conventional lead-acid battery and can be compactly established, has a great installation effects as a distributed energy storage system in the urban area which consumes big electric power. For the power company, NAS battery contributes to the load leveling, the supply capability up at

Hideki Rachi

2008-01-01

434

Human Embryonic Stem Cell Research: An Argument for National Research Review  

Microsoft Academic Search

The US National Academy of Sciences (NAS) recently published voluntary guidelines for human embryonic stem (hES) cell research. The NAS guidelines propose two levels of oversight. At the local level, research institutions are to create Embryonic Stem Cell Research Oversight (ESCRO) committees with a mandate to assess the scientific merit and ethical acceptability of hES cell research. At the national

FRANÇOISE BAYLIS; JASON SCOTT ROBERT

2006-01-01

435

RISK ANALYSIS OF HUMAN PERFORMANCE IN AVIATION MAINTENANCE  

Microsoft Academic Search

The National Airspace System (NAS) in the United States is a complex system involving many interrelated factors and actors. There are a plethora of diverse human, technical, environmental, and organizational factors that affect the performance of the NAS. While numerous methodologies exist for Probabilistic Risk Assessment in complex engineering systems, these specialized tools are somewhat limited in their use for

James T. Luxhøj

436

Impacts of new agents for multiple myeloma on development of secondary myelodysplastic syndrome and acute myeloid leukemia.  

PubMed

The use of new agents (NAs) such as bortezomib, thalidomide, and lenalidomide has extended the survival of patients with multiple myeloma (MM). However, whether long-term treatment using NAs may increase the risk of second primary malignancies is a concern. Three hundred and thirty-three patients with MM were treated at our hospital from 1998 to 2013. Additional chromosomal abnormalities (CAs), associated with secondary myelodysplastic syndrome/acute myeloid leukemia, were observed in 13 of 152 users of NAs, but in 38 of 181 non-users of NAs. The cumulative CA incidence was higher in non-users of NAs. The CAs frequently observed were 13q-, 20q-, +8 in users of NAs, while -5/5q- and -7/7q- were detected in non-users of NAs. The total dose and treatment period of NAs did not differ between CAs-positive and -negative patients. However, a higher dose of melphalan was observed to have been used in patients who had CAs. Longer follow-up periods are necessary for an accurate risk assessment. PMID:24850453

Hamano, Airi; Shingaki, Sumito; Abe, Yu; Miyazaki, Kanji; Sekine, Rieko; Nakagawa, Yasunori; Tsukada, Nobuhiro; Hattori, Yutaka; Suzuki, Kenshi

2014-04-01

437

The next accreditation system in radiology: a report from the APDR residency structure committee.  

PubMed

In a move to emphasize the educational outcomes of training programs, the ACGME has created the Next Accreditation System (NAS). The stated goals of NAS include aiding the ACGME in the accreditation of programs based on educational outcome measures, decreasing program burdens associated with the conventional process-based approach to ACGME accreditation, allowing good programs to innovate while enabling struggling programs to steadily improve, and providing public accountability for outcomes. Diagnostic radiology is among the first group of specialties to undergo NAS implementation and began operating under the NAS in July 2013. This article describes the various components of the NAS and explains the new elements, including the clinical learning environment review program, the milestones, the clinical competency committee, and the self-study visits. PMID:24035006

Nicholson, Brandi T; Paladin, Angelisa M; Oldham, Sandra A; Hudson, Kathleen T; Weissman, Barbara N; Wissman, Robert D; Davis, Lawrence P; Reddy, Gautham P; Heitkamp, Darel E

2014-04-01

438

Assessing the toxicity of naphthenic acids using a microbial genome wide live cell reporter array system.  

PubMed

Mixtures of naphthenic acids (NAs), which include cyclopentyl and cyclohexyl carboxylic acids, have been suggested to be toxic components in oils spills, effluents from the petrochemical industry and in oil sands process waters (OSPW). The present study demonstrated, for the first time, an application of a high throughput live bacterial cell array in a genome-scale investigation of the toxic mechanisms of environmental chemicals, a commercial NAs technical mixture extracted from crude oil. Real time gene profiling of time- and concentration- dependent responses of live cells exposed to NAs for three hours was conducted using a library of 1800 fluorescent transcriptional reporters for Escherichia coli (E. coli) growing in 384-well plates. The response patterns obtained after exposure to NAs suggested that the primary cellular responses were up-regulation of genes in the pentose phosphate pathway, involved in the molecular function of NADP or NADPH binding, and down-regulation of the ATP-binding cassette (ABC) transporter complex. Transcriptional networks that were significantly modulated by NAs included those that were regulated by transcriptional factors such as CRP-, RecA-, and GadE. Down-regulation of the SOS response pathway suggested that DNA damage might not be the direct result of NAs within the first three hours of exposure. However, CRP-dependent genes modulated by exposure to NAs indicated that the cellular level of cyclic AMP was altered immediately upon exposure of cells to NAs. Furthermore, the linear range of the concentration-response curve of the selected gene reporters encompassed a range of concentrations between 10 and 1000 mg NAs/L, which covers concentrations typically observed in the environment and makes this assay system ideal for the detection of environmental NAs. PMID:21309546

Zhang, Xiaowei; Wiseman, Steve; Yu, Hongxia; Liu, Hongling; Giesy, John P; Hecker, Markus

2011-03-01

439

Naphthenic acids in coastal sediments after the hebei spirit oil spill: a potential indicator for oil contamination.  

PubMed

Naphthenic acids (NAs) as toxic components in most petroleum sources are suspected to be one of the major pollutants in the aquatic environment following oil spills, and the polarity and persistence of NAs make it a potential indicator for oil contamination. However, the contamination and potential effects of pollutants in oil spill affected areas remain unknown. To investigate NAs in oil spill affected areas, a sensitive method was first established for analysis of NAs, together with oxy-NAs in sediment samples by UPLC-QTOF-MS. Then the method was applied to determine the NA mixtures in crude oil, weathered oil, and sediments from the spilled sites after the Hebei Spirit oil spill, Taean, South Korea (Dec. 2007). Concentrations of NAs, O3-NAs, and O4-NAs were found to be 7.8-130, 3.6-44, and 0.8-20 mg kg(-1) dw in sediments from the Taean area, respectively, which were much greater than those measured in the reference sites of Manlipo and Anmyundo beaches. Concentrations of NAs were 50-100 times greater than those (0.077-2.5 mg kg(-1) dw) of PAHs in the same sediment samples, thus the ecological risk of NAs in oil spill affected areas deserves more attention. The sedimentary profiles of oil-derived NAs and background NAs centered around compounds with 21-35 and 12-21 carbons, respectively, indicating that the crude-derived NA mixtures originating from the 2007 oil spill were persistent. Acyclic NAsn=5-20 were easily degraded compared to cyclic NAsn=21-41 during the oil weathering processes, and the ratio of oxy-NAsn=21-41 relative to NAsn=21-41 could be a novel index to estimate the degree of oil weathering in sediments. Altogether, the persistent oil-derived NAsn=21-41 could be used as a potential indicator for oil-specific contamination, as such compounds would not be much affected by the properties of coastal sediments possibly due to the high sorption of the negatively charged compounds (NAs) in sediment. PMID:24579908

Wan, Yi; Wang, Beili; Khim, Jong Seong; Hong, Seongjin; Shim, Won Joon; Hu, Jianying

2014-04-01

440

Effect of molecular structure on the relative reactivity of naphthenic acids in the UV/H?O? advanced oxidation process.  

PubMed

The large volume of oil sands process-affected water (OSPW) produced by the oil sands industry in Northern Alberta, Canada, is an environmental concern. The toxicity of OSPW has been attributed to a complex mixture of naturally occurring acids, including naphthenic acids (NAs). Highly cyclic or branched NAs are highly biopersistent in tailings ponds, thus understanding structure-reactivity relationship for NAs is very important for OSPW reclamation. In this study, we hypothesized that large, branched and cyclic NAs may be better oxidized in the UV/H(2)O(2) process than small, linear and acyclic NAs. Relative rate measurements using binary mixtures of model NA compounds confirmed that reactivity favored compounds with more carbons, and also favored NAs with one saturated ring, relative to the corresponding linear NA. However, for model compound with three rings, no increased reactivity was observed relative to monocyclic NA. UV/H(2)O(2) treatment of OSPW confirmed our findings with model compounds, indicating that the compounds with more carbons are favored for degradation. However, increasing the number of rings (or double bond equivalents) in OSPW NAs did not show any clear structure-reactivity. Microbial degradation studies of the UV/H(2)O(2) treated OSPW should be conducted to examine the overall benefit of this treatment for the real applications. PMID:22934634

Afzal, Atefeh; Drzewicz, Przemys?aw; Pérez-Estrada, Leónidas A; Chen, Yuan; Martin, Jonathan W; Gamal El-Din, Mohamed

2012-10-01

441

Microwave treatment of naphthenic acids in water.  

PubMed

Naphthenic acids (NAs) are natural constituents of bitumen and crude oil. These compounds are concentrated as part of the oil sands process water (OSPW) during petroleum refining and separation from oil sands. NAs are considered among the major water contaminants in OSPW due to their toxicity and environmental recalcitrance. A laboratory scale microwave system was developed and experiments were conducted to determine the efficiency of NA degradation during microwave treatment. The effects of water source and quality (deionized lab water and river water) and of TiO(2) catalyst in the degradation process were also investigated. Degradation kinetic parameters for both total NAs and individual z-family were calculated. The microwave system degraded OSPW NAs and commercial Fluka NAs in river water in the presence of TiO(2) rapidly, producing half-life values of 3.32 and 3.61 hours, respectively. Toxicity assessments of the NA samples pre-and post-treatment indicated that the microwave system reduced overall toxicity of water containing Fluka NAs from high (5 min. IC(50) v/v = 15.85%) to moderate (5 min. IC(50) v/v = 36.45%) toxicity levels. However, a slight increase in toxicity was noted post-treatment in OSPW NAs. PMID:20623403

Mishra, Sabyasachi; Meda, Venkatesh; Dalai, Ajay K; Headley, John V; Peru, Kerry M; McMartin, Dena W

2010-08-01

442

Impact of ozonation on naphthenic acids speciation and toxicity of oil sands process-affected water to Vibrio fischeri and mammalian immune system.  

PubMed

Oil sands process-affected water (OSPW) is the water contained in tailings impoundment structures in oil sands operations. There are concerns about the environmental impacts of the release of OSPW because of its toxicity. In this study, ozonation followed by biodegradation was used to remediate OSPW. The impacts of the ozone process evolution on the naphthenic acids (NAs) speciation and acute toxicity were evaluated. Ion-mobility spectrometry (IMS) was used to preliminarily separate isomeric and homologous species. The results showed limited effects of the ozone reactor size on the treatment performance in terms of contaminant removal. In terms of NAs speciation, high reactivity of NAs with higher number of carbons and rings was only observed in a region of high reactivity (i.e., utilized ozone dose lower than 50 mg/L). It was also found that nearly 0.5 mg/L total NAs was oxidized per mg/L of utilized ozone dose, at utilized ozone doses lower than 50 mg/L. IMS showed that ozonation was able to degrade NAs, oxidized NAs, and sulfur/nitrogenated NAs. Complete removal of toxicity toward Vibrio fischeri was achieved after ozonation followed by 28-day biodegradation period. In vitro and in vivo assays indicated that ozonation reduced the OSPW toxicity to mice. PMID:23683033

Wang, Nan; Chelme-Ayala, Pamela; Perez-Estrada, Leonidas; Garcia-Garcia, Erick; Pun, Jonathan; Martin, Jonathan W; Belosevic, Miodrag; Gamal El-Din, Mohamed

2013-06-18

443

Effect of alkyl side chain location and cyclicity on the aerobic biotransformation of naphthenic acids.  

PubMed

Aerobic biodegradation of naphthenic acids is of importance to the oil industry for the long-term management and environmental impact of process water and wastewater. The effect of structure, particularly the location of the alkyl side chain as well as cyclicity, on the aerobic biotransformation of 10 model naphthenic acids (NAs) was investigated. Using an aerobic, mixed culture, enriched with a commercial NA mixture (NA sodium salt; TCI Chemicals), batch biotransformation assays were conducted with individual model NAs, including eight 8-carbon isomers. It was shown that NAs with a quaternary carbon at the ?- or ?-position or a tertiary carbon at the ?- and/or ?'-position are recalcitrant or have limited biodegradability. In addition, branched NAs exhibited lag periods and lower degradation rates than nonbranched or simple cyclic NAs. Two NA isomers used in a closed bottle, aerobic biodegradation assay were mineralized, while 21 and 35% of the parent compound carbon was incorporated into the biomass. The NA biodegradation probability estimated by two widely used models (BIOWIN 2 and 6) and a recently developed model (OCHEM) was compared to the biodegradability of the 10 model NAs tested in this study as well as other related NAs. The biodegradation probability estimated by the OCHEM model agreed best with the experimental data and was best correlated with the measured NA biodegradation rate. PMID:24941126

Misiti, Teresa M; Tezel, Ulas; Pavlostathis, Spyros G

2014-07-15

444

When to stop nucleos(t)ide analogues treatment for chronic hepatitis B? Durability of antiviral response  

PubMed Central

Introduction of nucleos(t)ide analogues (NAs) for oral antiviral therapy has dramatically improved the clinical outcome in patients with chronic hepatitis B (CHB). Although current international guidelines for the management of CHB provide information regarding when to begin the antiviral therapy with NAs, there is no clear consensus on when to stop the treatment, especially for those who respond to the therapy. Hepatitis B surface antigen loss has been regarded as an ideal endpoint of oral antiviral therapy with NAs, however since this is rarely achieved, practical endpoints have been suggested by the international guidelines. Despite the stopping rules recommended by the international guidelines, whether oral antiviral therapy with NAs can be safely discontinued is of major concern. While attention has been drawn to whether antiviral treatment with NAs can be a finite therapy, there is lack of sufficient data on off-treatment durability of highly potent NAs. Based on the available evidences, current guidelines for stopping NA therapy seems to be inadequate in terms of off-treatment durability, with relapse rates of more than 40% for both hepatitis Be antigen (HBeAg)-positive and HBeAg-negative patients. Therefore, further studies are required to accumulate data on off-treatment durability of highly potent NAs, and future studies are warranted to identify adequate predictive markers that could provide supplementary information to guide the timing of stopping NA therapy.

Kang, Wonseok; Park, Jun Yong

2014-01-01

445

Harnessing oil sands microbial communities for use in ex situ naphthenic acid bioremediation.  

PubMed

The caustic hot water extraction process used to release bitumen from the Alberta oil sands generates large volumes of tailings waste, or oil sands process water (OSPW). OSPW contains several components of environmental concern including diluents, polyaromatic hydrocarbons, heavy metals, and naphthenic acids (NAs); the latter are of particular concern as they are acutely toxic to aquatic organisms and mammals. Studies have demonstrated that the naturally occurring OSPW bacteria are capable of metabolizing the NAs. However, this in situ process takes place over hundreds of years, and is incomplete, leaving a recalcitrant fraction of NAs intact. In this study we explore options for recovering and harnessing the naturally occurring OSPW bacteria for potential future use in an aerobic ex situ OSPW treatment system. Here we evaluate our recovered microbes on their ability to degrade two model NAs, cyclohexane carboxylic acid and cyclohexane acetic acid. Using OSPW as a source for a bacterial inoculum, we were able to compare single and multispecies OSPW cultures, grown as either a biofilm, or as a planktonic suspension. Furthermore, we examined the effect of available nutrients on the ability of these cultures to degrade NAs. All biofilms were grown using the Calgary Biofilm Device. GC-MS, and GC-FID reveal that multispecies biofilm and planktonic cultures are each capable of degrading both NAs; a trait not observed for single species cultures. Moreover, complementary carbon sources have a tangible effect on the ability of the cultures to initiate the degradation of the NAs. PMID:24325800

Demeter, Marc A; Lemire, Joe; George, Iain; Yue, Gordon; Ceri, Howard; Turner, Raymond J

2014-02-01

446

Phase I Clinical Trial of Oral Curcumin: Biomarkers of Systemic Activity and Compliance  

Microsoft Academic Search

Curcumin, a polyphenolic antioxidant derived from a dietary spice, exhibits anticancer activity in rodents and in humans. Its efficacy appears to be related to induction of glutathione S-transferase enzymes, inhibition of prostag- landin E2 (PGE2) production, or suppression of oxidative DNA adduct (M1G) formation. We designed a dose-escala- tion study to explore the pharmacology of curcumin in humans. Fifteen patients

Ricky A. Sharma; Stephanie A. Euden; Sharon L. Platton; Darren N. Cooke; Aisha Shafayat; Heather R. Hewitt; Timothy H. Marczylo; Bruno Morgan; David Hemingway; Simon M. Plummer; Munir Pirmohamed; Andreas J. Gescher; William P. Steward

2004-01-01

447

A Randomized, Double-Blind, Placebo-Controlled Study of Guanfacine Extended Release in Children and Adolescents With Attention-Deficit\\/Hyperactivity Disorder  

Microsoft Academic Search

OBJECTIVE.With this study we assessed the efficacy and safety of an extended-release formulation of guanfacine compared with placebo for the treatment of children and adolescents with attention-deficit\\/hyperactivity disorder. METHODS.In this multicenter, double-blind, placebo-controlled, fixed-dosage escala- tion study, patients aged 6 to 17 years were randomly assigned to 1 of 3 treatment groups of guanfacine extended release (2, 3, or 4

Joseph Biederman; Raun D. Melmed; Anil Patel; Jennifer Konow; Andrew Lyne; Noreen Scherer; Eli Lilly

2010-01-01

448

The acute and sub-chronic exposures of goldfish to naphthenic acids induce different host defense responses.  

PubMed

Naphthenic acids (NAs) are believed to be the major toxic component in oil sands process-affected water (OSPW) produced by the oil sands mining industry in Northern Alberta, Canada. We recently reported that oral exposure to NAs alters mammalian immune responses, but the effect of OSPW or NAs on the immune mechanisms of aquatic organisms has not been fully elucidated. We analyzed the effects of acute and sub-chronic NAs exposures on goldfish immune responses by measuring the expression of three pro-inflammatory cytokine genes, antimicrobial functions of macrophages, and host defense after challenge with a protozoan pathogen (Trypanosoma carassii). One week after NAs exposure, fish exhibited increased expression of pro-inflammatory cytokines (IFN?, IL-1?1, TNF-?2) in the gills, kidney and spleen. Primary macrophages from fish exposed to NAs for one week, exhibited increased production of nitric oxide and reactive oxygen intermediates. Goldfish exposed for one week to 20 mg/L NAs were more resistant to infection by T. carassii. In contrast, sub-chronic exposure of goldfish (12 weeks) to NAs resulted in decreased expression of pro-inflammatory cytokines in the gills, kidney and spleen. The sub-chronic exposure to NAs reduced the ability of goldfish to control the T. carassii infection, exemplified by a drastic increase in fish mortality and increased blood parasite loads. This is the first report analyzing the effects of OSPW contaminants on the immune system of aquatic vertebrates. We believe that the bioassays depicted in this work will be valuable tools for analyzing the efficacy of OSPW remediation techniques and assessment of diverse environmental pollutants. PMID:22227375

Hagen, Mariel O; Garcia-Garcia, Erick; Oladiran, Ayoola; Karpman, Matthew; Mitchell, Scott; El-Din, Mohamed Gamal; Martin, Jonathan W; Belosevic, Miodrag

2012-03-01

449

Commercial naphthenic acids and the organic fraction of oil sands process water downregulate pro-inflammatory gene expression and macrophage antimicrobial responses.  

PubMed

This is the first report showing that the organic fraction of oil sands process water (OSPW-OF), and commercial naphthenic acids (C-NAs), cause immunotoxicity. The exposure of mouse bone marrow-derived macrophages (BMDM) to different amounts of C-NAs or OSPW-OF, did not affect cell viability in vitro. We examined whether exposure of BMDM to C-NAs or OSPW-OF affected various antimicrobial responses of these cells. A dose-dependent decrease in nitric oxide response was observed after treatment of BMDM with OSPW-OF, but not with C-NAs. Although OSPW-OF and C-NAs both down-regulated the respiratory burst response of BMDM, the suppression of the production of reactive oxygen intermediates was more pronounced in cells treated with OSPW-OF. Treatment with OSPW-OF or C-NAs reduced BMDM phagocytosis of zymosan and latex beads. The decrease of BMDM antimicrobial response after exposure to OSPW-OF or C-NAs, was accompanied by decreased pro-inflammatory cytokine gene expression. Oral exposure of mice to OSPW-OF caused down-regulation in the expression of genes encoding pro-inflammatory cytokines IFN?, IL-1? and CSF-1. Our findings indicated that OSPW causes immunotoxic effects that may impair the ability of an exposed host to defend against infectious disease. Furthermore, given the differences between the effects of OSPW-OF and C-NAs, C-NAs should not be assumed to be a direct surrogate for the immunotoxic chemical species in OSPW. PMID:21396992

Garcia-Garcia, Erick; Pun, Jonathan; Perez-Estrada, Leonidas A; Din, Mohamed Gamal-El; Smith, Daniel W; Martin, Jonathan W; Belosevic, Miodrag

2011-05-30

450

Naphthenic acids and other acid-extractables in water samples from Alberta: what is being measured?  

PubMed

There is increasing international interest in naphthenic acids (NAs, classical formula C(n)H(2n+Z)O(2)) found in the oil sands from Alberta, Canada and in petroleum from around the world. The complexity of NAs poses major analytical challenges for their quantification and characterization. We used ultrahigh resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR MS) to probe the make up of NAs from various sources by searching for peaks corresponding to the formula C(n)H(2n+Z)O(x), for combinations of n=8 to 30, Z=0 to -12, and x=2 to 5. The sources included three commercial NAs preparations, and the acid-extractable organics from eight oil sand process-affected waters (OSPW) and from six surface fresh waters. Extracts from OSPW contained between 1 and 7% sulfur. The mass spectra showed between 300 and 1880 peaks, with >99% of the peaks having m/z between 145 and 600. In most cases, <20% of the peaks were assigned as classical NAs (x=2) and oxy-NAs (x=3 to 5). The classical NAs from the OSPW were predominantly Z=-4 and -6, whereas those from the fresh waters were mainly Z=0, with palmitic and stearic acids being the major components in the fresh waters. Remarkably, when the peak abundances were considered, <50% of the total abundance could be assigned to the classical and oxy-NAs. Thus, >50% of the compounds in the extracts of OSPW were not "naphthenic acids". Based on these findings, it appears that the term "naphthenic acids", which has been used to describe the toxic extractable compounds in OSPW, should be replaced by a term such as "oil sands tailings water acid-extractable organics (OSTWAEO)". Classical and oxy-NAs are components of OSTWAEO, but this term would not be as misleading as "naphthenic acids". PMID:20825979

Grewer, David M; Young, Rozlyn F; Whittal, Randy M; Fedorak, Phillip M

2010-11-01

451

The NYC native air sampling pilot project: using HVAC filter data for urban biological incident characterization.  

PubMed

Native air sampling (NAS) is distinguished from dedicated air sampling (DAS) devices (eg, BioWatch) that are deployed to detect aerosol disseminations of biological threat agents. NAS uses filter samples from heating, ventilation, and air conditioning (HVAC) systems in commercial properties for environmental sampling after DAS detection of biological threat agent incidents. It represents an untapped, scientifically sound, efficient, widely distributed, and comparably inexpensive resource for postevent environmental sampling. Calculations predict that postevent NAS would be more efficient than environmental surface sampling by orders of magnitude. HVAC filter samples could be collected from pre-identified surrounding NAS facilities to corroborate the DAS alarm and delineate the path taken by the bioaerosol plume. The New York City (NYC) Native Air Sampling Pilot Project explored whether native air sampling would be acceptable to private sector stakeholders and could be implemented successfully in NYC. Building trade associations facilitated outreach to and discussions with property owners and managers, who expedited contact with building managers of candidate NAS properties that they managed or owned. Nominal NAS building requirements were determined; procedures to identify and evaluate candidate NAS facilities were developed; data collection tools and other resources were designed and used to expedite candidate NAS building selection and evaluation in Manhattan; and exemplar environmental sampling playbooks for emergency responders were completed. In this sample, modern buildings with single or few corporate tenants were the best NAS candidate facilities. The Pilot Project successfully demonstrated that in one urban setting a native air sampling strategy could be implemented with effective public-private collaboration. PMID:21793731

Ackelsberg, Joel; Leykam, Frederic M; Hazi, Yair; Madsen, Larry C; West, Todd H; Faltesek, Anthony; Henderson, Gavin D; Henderson, Christopher L; Leighton, Terrance

2011-09-01

452

Cigarette Smoking and Neonatal Outcomes in Depressed and Non-Depressed Opioid-Dependent Agonist-Maintained Pregnant Patients  

PubMed Central

Aims To investigate whether cigarette smoking and/or depression contribute to neonatal abstinence syndrome (NAS) severity. Design Cohort study analyzing data from a randomized, controlled trial of methadone versus buprenorphine. Setting Seven study sites that randomized patients to study conditions and provided comprehensive addiction treatment to pregnant patients. Participants 119 of 131 opioid-dependent pregnant patients who completed the MOTHER study. Measurements Smoking data and depression status were obtained from the Addiction Severity Index and Mini International Neuropsychiatric Interview, respectively. Neonatal outcomes (birth weight, preterm delivery and NAS pharmacologic treatment) were collected from the medical charts. Study site was a fixed-effect factor in all analyses. Findings Cigarette smoking was reported by 94% of participants and depression identified in 35%. Smoking was associated with low birth weight, preterm delivery, and NAS pharmacologic treatment in both depressed and non-depressed participants. The association between smoking and NAS treatment differed significantly between depressed and non-depressed participants. Among non-depressed participants, adjusting for site and illicit drug use, each additional average cigarette per day (CPD) increased the odds of NAS treatment by 12% [95%CI: (1.02-1.23), p=0.02]. Among depressed participants, each additional average CPD did not statistically increase the odds of NAS treatment [OR: 0.94, 95% CI: (0.84-1.04), p=0.23]. Conclusions These results are consistent with the hypothesis that NAS expression is influenced by many factors. The relationship between CPD and NAS pharmacologic treatment is attenuated among depressed women in this study for reasons currently unknown. Further investigations are needed to clarify the complex relationships among maternal smoking, depression, and NAS.

Chisolm, Margaret S.; Acquavita, Shauna P.; Kaltenbach, Karol; Winklbaur, Bernadette; Heil, Sarah H.; Martin, Peter R.; Stine, Susan M.; Coyle, Mara; Leoutsakos, Jeannie-Marie S.; Tuten, Michelle; Jansson, Lauren M.; Backer, Penina M.; Jones, Hendree E.

2012-01-01

453

Microvariabilidade da polarização óptica e do fluxo infravermelho de 3C 279  

NASA Astrophysics Data System (ADS)

Neste trabalho mostramos um estudo sobre a existência e o comportamento da microvariabilidade na polarização óptica no blazar 3C 279. As medidas de polarização foram feitas durante quatro noites em março/2002 com o telescópio de 2.15 m do CASLEO, utilizando o polarímetro CASPROF. As observações mostraram que o grau de polarização linear é composto por duas componentes: uma relativa ao flickering em escalas de tempo de minutos e outra com variações em escalas de tempo de dias. Neste último caso a variação do grau de polarização está correlacionada com variações intraday no infravermelho próximo, cujos dados foram obtidos simultaneamente durante duas noites no telescópio de 1.60 m do LNA, utilizando a CamIV. Além disso, o ângulo de polarização apresentou uma variação súbita de mais de 10 graus em algumas horas, o que poderia ser causado pela injeção de um novo choque no jato. Esta idéia é apoiada pelo comportamento da variabilidade no infravermelho em escalas de tempo mais longas, que foi acompanhado durante três meses após o término da campanha coordenada com observações adicionais no LNA.

Andruchow, I.; Cellone, S. A.; Romero, G. E.; Dominici, T. P.; Abraham, Z.

2003-08-01

454

Low Density Radio Communications Link (LDRCL) Operational Test and Evaluation (OT/E) integration and operation test plan  

NASA Astrophysics Data System (ADS)

This plan addresses the Operational Test and Evaluation (OT&E) Integration testing of the Low Density Radio Communications Link (LDRCL) equipment in the current National Airspace System (NAS) environment. The approach and concept were to conduct integration tests with appropriate NAS systems to verify that NAS requirements and LDRCL specifications requirements were satisfied. This will be accomplished by conducting factor acceptance and site acceptance tests at the contractor's facility in Richardson, Texas, and extensive integration tests at the following key sites: San Antonio, Texas; Scurry, Texas; and Mina, Nevada.

Bell, Wayne E.; Melillo, Michael R.; Tran, Tuan A.; Warren, John

1992-10-01

455

Alternative Architectures for Distributed Work in the National Airspace System  

NASA Technical Reports Server (NTRS)

The architecture for the National Airspace System (NAS) in the United States has evolved over time to rely heavily on the distribution of tasks and control authority in order to keep cognitive complexity manageable for any one individual. This paper characterizes a number of different subsystems that have been recently incorporated in the NAS. The goal of this discussion is to begin to identify the critical parameters defining the differences among alternative architectures in terms of the locus of control and in terms of access to relevant data and knowledge. At an abstract level, this analysis can be described as an effort to describe alternative "rules of the game" for the NAS.

Smith, Philip J.; Billings, Charles E.; Chapman, Roger; Obradovich, Heintz; McCoy, C. Elaine; Orasanu, Judith

2000-01-01

456

LISA 8 Science Organizing Committee and Local Organizing Committee LISA 8 Science Organizing Committee and Local Organizing Committee  

NASA Astrophysics Data System (ADS)

Science Organising Committee (SOC) Tom Abel, Stanford University Odylio Aguiar, Instituto Nacional de Pesquisas Espaciais Tal Alexander, Wizemann Institute Peter Bender, University of Colorado Pierre Binetruy, APC - College de France Sasha Buchman, Stanford University Robert Byer, Stanford University Manuela Campanelli, University of Texas Joan Centrella, NASA/Goddard Massimo Cerdonio, University of Padova Eugenio Coccia, University of Roma-2 Neil Cornish, Montana State University Michael Cruise, University of Birmingham Curt Cutler, NASA/JPL Karsten Danzmann, University of Hannover Sam Finn, Penn State University Jens Gundlach, NPL Gerhard Heinzel, Max-Planck-Institut fuer Gravitationsphysik Craig Hogan, University of Washington Jim Hough, University of Glasgow Scott Hughes, MIT Oliver Jennrich, ESTEC Philippe Jetzer, University Zurich Seiji Kawamura, National Observatory, Japan Alberto Lobo, ICE-CSIC and IEEC Avi Loeb, Harvard University Piero Madau, Lick Observatory Yannick Mellier, IAP, Paris Peter Michelson, Stanford University Guido Mueller, University of Florida Sterl Phinney, Caltech Tom Prince, NASA/JPL Doug Richstone, University of Michigan Bernard Schutz, AEI Potsdam Tuck Stebbins, NASA/Goddard Tim Sumner, Imperial College, London Ke-Xun Sun, Stanford University Kip Thorne, Caltech Michele Vallisneri, NASA/JPL Alberto Vecchio, University of Birmingham Jean-Yves Vinet, OCA, Nice Stefano Vitale, University of Trento Rai Weiss, MIT Nick White, NASA/Goddard Local Organising Committee (LOC) Sasha Buchman (Stanford University) Robert Byer (Stanford University) Sara Charbonneau-Lefort (Stanford University) Nancy Christianson (Stanford University) John Conklin (Stanford University) Dan DeBra (Stanford University) Jan Goebel (Stanford University) Vivian Drew (Stanford University) Ke-Xun Sun (Stanford University) Lucy Zhou (Stanford University) Andrea Zoellner (Stanford University)

2011-05-01

457

Next Generation Security for the 10,240 Processor Columbia System.  

National Technical Information Service (NTIS)

This presentation includes a discussion of the Columbia 10,240-processor system located at the NASA Advanced Supercomputing (NAS) division at the NASA Ames Research Center which supports each of NASA's four missions: science, exploration systems, aeronaut...

T. Hinke P. Kolano D. Shaw C. Keller D. Tweton T. Welch W. B. Liu

2005-01-01

458

Knowledge-Based Autonomous Test Engineer (KATE).  

National Technical Information Service (NTIS)

Mathematical models of system components have long been used to allow simulators to predict system behavior to various stimuli. Recent efforts to monitor, diagnose, and control real-time systems using component models have experienced similar success. NAS...

C. L. Parrish B. L. Brown

1991-01-01

459

Poverty Among Working Families: Findings from Experimental Poverty Measures, 1998. Special Studies. Current Population Reports.  

National Technical Information Service (NTIS)

This report examines poverty among working families with children using experimental measures of poverty that are based on recommendations by the National Academy of Sciences (NAS) Panel on Poverty and Family Assistance. These experimental poverty measure...

J. Iceland

2000-01-01

460

2002 Microgravity Materials Science Conference.  

National Technical Information Service (NTIS)

The 2002 Microgravity Materials Science Conference was held June 25-26, 2002, at the Von Braun Center, Huntsville, Alabama. Organized by the Microgravity Materials Science Discipline Working Group, sponsored by the Physical Sciences Research Division, NAS...

D. Gillies N. Ramachandran K. Murphy D. McCauley N. Bennett

2003-01-01

461

ONTOGENY OF PROTEINS FOR USE AS BIOMARKERS OF DEVELOPMENTAL NEUROTOXICITY.  

EPA Science Inventory

The developing nervous system can be uniquely susceptible to adverse effects following exposure to environmental chemicals, and several advisory panels (e.g. ILSI, NRC, NAS) have highlighted the need for rapid and sensitive developmental neurotoxicity testing methods. Measurement...

462

61 FR 57586 - Diseases Associated With Exposure to Certain Herbicide Agents (Prostate Cancer and Acute and...  

Federal Register 2010, 2011, 2012, 2013

...Orange: Health Effects of Herbicides...called to the attention of NAS. The...toxicological effects in animals...involving herbicide exposure and its effects...synergistic effects of exposure to other substances...personally aware of...

1996-11-07

463

75 FR 32540 - Health Effects Not Associated With Exposure to Certain Herbicide Agents  

Federal Register 2010, 2011, 2012, 2013

...including small intestine and anus); hepatobiliary cancers (liver, gallbladder and bile...including small intestine and anus); hepatobiliary cancers (liver, gallbladder, and...herbicide exposure and colorectal cancer. Hepatobiliary Cancers For Update 2006, NAS...

2010-06-08

464

76 FR 77939 - Proposed Provision of Navigation Services for the Next Generation Air Transportation System...  

Federal Register 2010, 2011, 2012, 2013

...129, and 135 Proposed Provision of Navigation Services for the Next Generation Air...Transition to Performance-Based Navigation (PBN) AGENCY: Federal Aviation Administration...S. National Airspace System (NAS) navigation infrastructure to enable...

2011-12-15

465

Current Practices in Runway Configuration Management (RCM) and Arrival/Departure Runway Balancing (ADRB).  

National Technical Information Service (NTIS)

Significant air traffic increases are anticipated for the future of the National Airspace System (NAS). To cope with future traffic increases, fundamental changes are required in many aspects of the air traffic management process including the planning an...

D. M. Williams G. W. Lohr

2008-01-01

466

Saturn and Enceladus Electrical Link  

NASA Video Gallery

This animated graphic shows how Saturn and its moon Enceladus are electrically linked. Magnetic field lines, invisible to the human eye but detectable by the fields and particles instruments on NAS...

467

Marijuana and Health.  

National Technical Information Service (NTIS)

A committee of the NAS/IOM reviewed the literature to determine any possible health hazards associated with marijuana use, to identify any potential therapeutic uses, to recommend promising research directions, and to assess federal research programs in m...

1982-01-01

468

Revisão sistemática sobre obesidade em adolescentes brasileiros  

Microsoft Academic Search

Resumo - O propósito deste estudo foi revisar, de forma sistemática, a literatura nacional sobre a prevalência e fatores associados à obesidade em adolescentes. A busca foi realizada nas bases de dados Pubmed e Bireme, através dos descritores: \\

Rafael Miranda Tassitano; Maria Cecília Marinho Tenório; Pedro C Hallal

469

Comparative Demonstration of Active and Semi-Passive In Situ Bioremediation Approaches for Perchlorate Impacted Groundwater: Active In Situ Bioremediation Demonstration (Aerojet Facility).  

National Technical Information Service (NTIS)

Perchlorate is an inorganic anion that consists of chlorine bonded to four oxygen atoms. It is a primary ingredient in solid rocket propellant and has been used for decades by Department of Defense (DOD), National Aeronautics and Space Administration (NAS...

E. Cox T. Krug

2012-01-01

470

75 FR 13051 - Presumptions of Service Connection for Persian Gulf Service  

Federal Register 2010, 2011, 2012, 2013

...Asia. The NAS noted that diarrheal diseases were the most common illnesses manifest during the 1991...that conflict. Although diarrheal diseases were one of the most common major infectious disease problems for troops during the...

2010-03-18

471

Degradation of Sodium beta''-Alumina Electrolyte in Contact with Sulfur/Sodium Polysulfide Melts.  

National Technical Information Service (NTIS)

Immersion of sodium beta '' alumina electrolyte in sodium polysulfide and pure sulfur melts, at Na/S battery operation temperatures, showed that the electrolyte was chemically attacked by the melts. The corrosion reactions mostly initiated and concentrate...

M. Liu

1986-01-01

472

IRIS Toxicological Review of Formaldehyde (Inhalation) (External Review Draft 2010)  

EPA Science Inventory

UPDATE EPA is currently revising its Integrated Risk Information System (IRIS) assessment of formaldehyde to address the 2011 NAS peer review recommendations. This assessment addresses both noncancer and cancer human health effects that are relevant to assessing ...

473

CONTRIBUTION OF SEMI-VOLATILE PARTICULATE MATTER TO AMBIENT SUSPENDED FINE PARTICLE MASS  

EPA Science Inventory

Scope: The periodic (5 years) review of the National Ambient Air Quality Standard (NAAQS) for particulate matter (PM) and the subsequent determination by EPA and NAS of particulate matter research needs have identified areas of uncertainty including exposure measurement th...

474

Artcc Maintenance Communication, Jacksonville.  

National Technical Information Service (NTIS)

The proposed Maintenance Communications System for NAS Stage A, Jacksonville ARTCC, provides an interphone switching system that meets the voice maintenance communications requirements for the facility. The best technical/economical approach is to expand ...

W. R. Miller

1968-01-01

475

Evaluation of EPA's Guidelines for Technologically Enhanced Naturally Occurring Radioactive Materials (TENORM).  

National Technical Information Service (NTIS)

In reports accompanying the appropriations bills for the Departments of Veterans Affairs, Housing and Urban Development, and Independent Agencies for Fiscal Years 1996 and 1997, Congress requested the EPA arrange for the National Academy of Sciences (NAS)...

2000-01-01

476

48 CFR 1552.223-72 - Care of laboratory animals.  

Code of Federal Regulations, 2013 CFR

...Care and Use of Laboratory Animals prepared by the Institute of Laboratory Animals Resources (NAS-NRC...in the regulations and standards as promulgated by the Agricultural...pursuant to the Laboratory Animal Welfare Act of August 24,...

2013-10-01

477

78 FR 46599 - Wild Horse and Burro Advisory Board Meeting  

Federal Register 2010, 2011, 2012, 2013

...Board will conduct a meeting that will provide an opportunity for the Advisory Board to attend presentations and engage with authors of the June 2013 National Research Council of the National Academies (NRC/NAS) Report entitled: ``Using Science to...

2013-08-01

478

Ridge Regression Signal Processing.  

National Technical Information Service (NTIS)

The introduction of the Global Positioning System (GPS) into the National Airspace System (NAS) necessitates the development of Receiver Autonomous Integrity Monitoring (RAIM) techniques. In order to guarantee a certain level of integrity, a thorough unde...

M. R. Kuhl

1990-01-01

479

Federal Aviation Administration Plan for Research, Engineering and Development, 1995.  

National Technical Information Service (NTIS)

The Federal Aviation Administration (FAA) manages and operates the National Airspace System (NAS), a significant national resource. However, the demands on this system are continuously growing, and changing technologies provide the opportunity to improve ...

1994-01-01

480

78 FR 78302 - Proposed Modification and Establishment of Air Traffic Service (ATS) Routes in the Vicinity of...  

Federal Register 2010, 2011, 2012, 2013

...the National Airspace System (NAS). DATES: Comments...Proposed Rulemaking Distribution System, which describes the...The navigation aid radials cited in the proposed...Choo, GA, 189[deg] radials; Choo Choo; to...

2013-12-26