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2008-07-01
The goal of this article is to do an investment analysis applying Real Options Theory in the plant Gas to Liquid (GTL). This analysis is the most indicated, because there are several flexibilities in this plant, related to the inputs (many products can be applied) as well the outputs (there are many possible combinations to use). In order to make the analysis as close as possible of reality and the most accurate it became fundamental to calculate the value that those flexibilities add to final value of the plant. It is going to be calculated the value of switch use of inputs (possibility to each semester to choose different resources) and the value of switch use of outputs (the possibility of the plant to produce more than one combination of outputs). Although in order to be feasible the implementation of the real option of switch use it is necessary to know if the added value is bigger or lesser from the cost of implementation. In the research it is achieve the conclusion that the value of switch use of inputs is lower than the cost of its implementation. (author)
1989-12-31
The process of conservation and treatment of wheat by irradiation was studied. The advantages of this method in relation to conventional method were analysed. The radiation effects were observed to different radiation doses on wheat metabolism, proteins, starch, alpha-amylases and physical-chemical characteristics. 30 refs., 22 tabs.
1993-12-31
This work presents discussions and comments concerning several aspects related to the utilization of tertiary winding in self transformers, based on several analysis proceeded by CHESF - the hydroelectric power company of Sao Francisco (northeast Brazil). This work objectives to provide material for the safe utilization of the above mentioned system. 7 refs., 8 figs., 3 tabs.
Como os Alunos do Ensino Mdio da Rede Estadual de So Paulo obtm Conhecimentos Astronmicos?
Atualmente vivencia-se um mundo globalizado onde os computadores e a internet permitiram um acesso rpido e seguro a todo tipo de informao e conhecimento. O presente trabalho visa analisar a maneira pela qual alunos de segundo grau da rede estadual da cidade de So Paulo obtiveram, caso tenham, conhecimentos bsicos de astronomia quanto aos fenmenos celestes que os rodeiam, tais como a sucesso dos dias e das estaes do ano, alm de question~los sobre fatos genricos tais como: o que vem a ser o Sol, o Big Bang, o que ocasionou a extino dos dinossauros. Para tanto foi elaborado um formulrio constando de questes de mltipla escolha, o qual foi aplicado no primeiro colegial diurno da Escola Estadual Guilherme de Almeida. Num espao amostral de 44 alunos constatou-se que 41% dos alunos adquiriram seus conhecimentos astronmicos na escola e 59% atravs da mdia em geral. Neste mesmo espao amostral apenas 11% dos alunos usaram computadores na escola, 41% na residncia, 5% no trabalho e 43% no utilizaram. O presente estudo revelou tambm que para 50% dos alunos o professor jamais utilizou um programa de computador a respeito de astronomia ou fez alguma apresentao sobre o tema. Embora em sua fase inicial este estudo revela claramente que a maioria dos alunos no obtm na escola seus conhecimentos astronmicos, estes provm de fontes no especificamente didtico-pedaggicas tais como filmes e revistas populares que no raramente geram conhecimentos incompletos e em muitos casos inclusive falhos.
1991-12-31
It is studied the influence of the h-heptane (n C{sub 7}) and diethyl phthalate, used as diluents, in the formation of the base 2-vinyl pyridine and divinylbenzene synthesized copolymer internal structure. 144 refs., 44 figs., 18 tabs.
1991-01-01
It is studied the influence of the h-heptane (n C7) and diethyl phthalate, used as diluents, in the formation of the base 2-vinyl pyridine and divinylbenzene synthesized copolymer internal structure. 144 refs., 44 figs., 18 tabs
1992-12-31
The mathematical modelling has been seen as an important tool to form an automation system for the operational control of the blast furnace. In this work such mathematical model was developed in order to represent the experimental results for the reduction degree, between 1173 k and 1673 k, of several charge materials. The prediction of the course of the reduction by the model was compared to the results obtained in bench scale, in same conditions of the cohesive zone of the blast furnace. The correlation obtained was about 80%. (author). 7 refs., 11 figs., 1 tab.
Sobre a largura da ltima superfcie de espalhamento
De acordo com o modelo do "Big-Bang", no universo primordial a matria estava em equilbrio trmico com a radiao. Com a expanso a temperatura da radiao cai. Quando a temperatura chega em torno dos 4.000K, os espalhamentos diminuem, comeando a recombinao dos prtons e eltrons em Hidrognio neutro (era conhecida como da recombinao). Ao final da recombinao, os ftons se propagam livremente sofrendo, em princpio, somente os efeitos do "redshift" cosmolgico. Esses ftons nos alcanam hoje como a radiao csmica de fundo (RCF), e parecem vir de uma superfcie esfrica ao nosso redor, tal que o raio dela a distncia que ele viajou desde seu ltimo espalhamento na poca da recombinao. Naturalmente, esse processo no ocorreu abruptamente, implicando na existncia de uma largura no espao dos "redshifts" que deve depender do modelo cosmolgico especfico e dos processos fsicos considerados. Neste trabalho analisamos os efeitos de diferentes modelos - a saber, aqueles com decaimento do vcuo L(t), criao de matria, quintessncia e gs de Chaplygin - sobre a ltima superfcie de espalhamento da RCF, em particular sua largura e a funo visibilidade, que determina a probabilidade de um fton ter tido seu ltimo espalhamento num "redshift" z. No caso particular dos modelos com decaimento do vcuo, existe uma forte dependncia da funo visibilidade com L(t). Tais efeitos podero ser testados atravs da anlise dos resultados de experimentos mais precisos que esto atualmente em andamento, como por exemplo, o WMAP.
2010-01-01
The structural stability, electronic structure, optical and thermodynamic properties of NaMgH3 have been investigated using the density functional theory. Good agreement is obtained for the bulk crystal structure using both the local density approximation (LDA) and the generalized gradient approximation (GGA) for the exchange-correlation energy. It is found from the electronic density of states (DOS) that the valence band is dominated by the hydrogen atoms while the conduction band is dominated by Na and Mg empty states. Also, the DOS reveals that NaMgH3 is a large gap insulator with direct band gap 3.4eV. We have investigated the optical response of NaMgH3 in partial band to band contributions and the theoretical optical spectrum is presented and discussed in this study. Optical response ...
1990-12-31
In water resources management, the tendency is to create taxes. It is a new idea, not accepted totally yet, because are some troubles, like adoption of water quality parameters, the unitary value of the taxes and the variation of this taxes in function of the pollutant contents of the water. (author). 9 refs
1999-07-01
The aim of the work was to propose strategies which facilitate manager's access to the information on energetic efficiency projects in the small industry aiming at the productivity increase and of the products quality. Brazilian experience is discussed.
1995-03-01
The conventional radiology defines and characterizes the bone neoplasms in majority of cases, but computed tomography and magnetic resonance imaging give indispensable information to surgery planning. The authors show the tomographic aspects of 17 bone neoplasms and the method`s importance in pre and posttreatment of these tumors. It was studied 17 cases (5 benigns and 12 maligns) with a short revision about the subject. (author). 11 refs, 17 figs.
1987-12-31
From the beginning of its activities, PETROBRAS has employed assessments of undiscovered petroleum resources in planning exploration. Assessment methods have evolved from qualitative early versions by progressive quantification, and by incorporation of probabilistic components. The method currently used in systematically assessing Brazilian basins is an adaptation of the method known as Exploration Play Analysis to the planning requirements of PETROBRAS. 46 refs.
1984-01-01
Metalaxyl and carbendazim at 10 and 100 ppm concentration have no influence on the biological activity of Humic Gley and Yellow Red Latosol soils as measured by respirometry. Carbendazim added to the Humic Gley soil at concentration of 500 ppm showed an inhibitory influence on the biological activity of this soil. (Author)
1999-07-01
The article discusses the environment, social and economic costs in the energetic planning. In this context, it is introduced the Complete Costs Evaluation boarding and it is presented a case study based on a kind of fertilizer produced in Sao Paulo, a Brazilian state. Quantitative and qualitative evaluation were also presented and the results were discussed.
The relationship between advanced very high resolution radiometer (AVHRR)/NOAA and thematic mapper (TM)/LANDSAT data is evaluated for estimating the contact area of the savanna and forest. This study is a contribution to the development of a multisensor a...
2009-01-01
Density of electron states (DOS) measured by X-ray photoelectron spectra (XPS) on single crystals of a ternary oxyborate Na3La9O3(BO3)8 (NLBO) are reported for the first time. The Na3La9O3(BO3)8 ternary oxyborate nonlinear single crystals were synthesized by spontaneous crystallization on a iridium cylinder put in melts consisting of binary oxides. The novelty of the present work is that it describes the complete experimental picture of the total density of states (TDOS) for the valence band obtained by means of X-ray photoelectron spectroscopy. We compare the DOS obtained by XPS with band structure calculation. The latter was performed within the density functional theory, using a full-potential linear augmented plane wave (FP-LAPW) ...
2007-01-01
Plasticized membranes using 1-phenyl-3-(2-thiazolyl)-2-thiourea (PTT) and 1-phenyl-3-(2-thiazolyl)-2-urea (PTU) have been prepared and explored as ytterbium ion-selective sensors. Effect of various plasticizers, viz. chloronaphthalene (CN), o-nitrophenyloctyl ether (o-NPOE), dibutylphthalate (DBP), dioctylsebacate (DOS) and anion excluders, sodium tetraphenylborate (NaTPB) and oleic acid (OA) was studied and improved membrane performance was observed. Optimum performance was noted with membrane of PTT having composition of PTT (3.5):PVC (80):DOS (160):NaTPB (1.5) in mg. The sensor works satisfactorily in the concentration range 1.2 x 10-7 to 1.0 x 10-2 M (detection limit 5.5 x 10-8 M) with a Nernstian slope of 19.7 mV decade-1 of activity. Wide pH range (3.0-8.0), fast response time (10 s), non-aqueous ...
2004-07-01
This work is dedicated to the discussion of inherent questions to the energy supply to isolated communities in the frame of the current policy of extension of modern energy options to all citizens (the access and the use of the energy), through the program 'Luz para Todos'. It still presents the adequacy of the proposal presented at the Agrener-2002 (FERREIRA and ANDRADE, 2002) to the new guidelines of the Brazilian electric sector for electrification on rural communities. (author)
1995-12-31
This work presents a mathematical modelling which uses the harmonic inductance concept on order to obtain voltage and torch equations of an induction machine. The methodology is presented. Two different situations are presented: the operation of the inducted motor feed by sinusoidal voltage wave and the operation of the same induction motor by a three-phase inductor 8 figs., 6 refs.
1996-12-31
This work shows a study in laboratory, of the influence of different rolling conditions, continuous cooling and chemical composition on bainitic microstructure and properties of a low carbon Nb-Ti-B steel another one with addition of Cu-Ni-Cr. The results showed that in both steels were possible to obtain a bainitic microstructure with different levels of mechanical properties depending on the proportion of acicular constituents. (author) 5 refs., 17 figs., 2 tabs.
1999-07-01
This paper analyses the strategies of the Latin-American agents PDVSA, PEMEX, YPF and Ecopetrol face to the double transformation: global re-structuration and deregulation of the national industries. The study focuses the traditional sectors of the petroleum industries (core business), including the petrochemical industries and new segments such as natural gas and electric power. The paper analyses the period 1992-1996, which is characterized by price instability, liberalization of the Latin-American markets and in the corporation-enterprise plane by successive mergings and acquisitions modifying the actors strategic behaviour.
1990-12-31
The effect of titanium content on the hot ductility of micro alloyed steels was studied in quantities above and below Ti/N stoichiometric ratio. Ti additions improved ductility in the low austenite and in the gamma/alpha transformation regions. Ductility decreases in the low austenite region due to dynamic precipitation of niobium and specially in the grain boundaries. 17 figs., 1 tab., 13 refs.
1984-12-31
Some existing empirical relations for determination of austenitic stainless steel ferrite content, and an analysis of its applicability on prediction of ingots behaviour during hot working, are presented. According to the authors, the results indicate that its possible to control and optimize the surface quality of the product through the calculation of a rolling index. 7 figs., 3 tabs., 9 refs.
1997-12-01
Vincristine is a drug used in chemotherapy for cancer treatment. The radiopharmaceuticals biodistribution or pharmacokinetics can be modify by drugs effect, diseases, surgery and radiotherapy. The absence of knowledge of these factors may result in an unexpected behavior of the radiopharmaceuticals. In this work was studied the effect of vincristine on biodistribution of pertechnetate used for thyroid and brain scintigraphy and 99 mTc-phytate used for hepatic scintigraphy. 5 refs., 5 tabs.
1991-12-31
This work describes the experience acquired by ELETRONORTE with the implementation of two power plants (Balbina and Samuel), concerning the supervision and control system to the generation groups of these power plants. This work also presents: the development of the project; the system`s configuration; the tests ran; the system`s performance; the existing situation, and future perspectives. 2 refs., 5 figs.
A lead and strontium isotope study was carried out on galena, barite and calcite from Pb-Ag syngenetic stratiform (Perau type) and hydrothermal veins (Panela type) deposits from Vale do Ribeira region (Sao Paulo and Parana states). The leads from the Pera...
2008-01-01
In the present work the procedure for the standardization of radionuclides using the 4pi(PC)-NaI(Tl) coincidence system was developed. The radionuclides selected were 201Tl, used in nuclear medicine, and 55Fe primary standard source, used for x-ray spectrometers calibration. The 4pi(PC)-NaI(Tl) is composed of a 4 proportional counter operated at 0.1MPa coupled to two NaI(Tl) crystals. The 201Tl decays by electron capture process followed by a prompt gamma-ray. The disintegration rate was determined by extrapolation technique using two methods: electronic discrimination and external absorbers. The radioactive sources were prepared in a 20 mug cm-2 thick Collodion film. The conventional electronic system was used. The observed events were registered by the TAC method. The ...
A Influncia Da Estrutura Organizacional Na Execuo Dos Processos De Manuteno
2003-01-01
No contexto atual de competitividade, uma eficiência maior dos processos executados pelo departamento de manutenção é um dos fatores que contribui paRI o aumento de produtividade das empresas. Diferentes autores têm reconhecido a importância da estrutura organizacional do departamento de manutençào no seu desempenho. Entretanto, esses autores não detalham a influência da estrutura organizacional para a adequada execução dos processos de manutenção. Este artigo descreve um trabalho cujo objetivo foi procurar entender como a estrutura organizacional influência os processos do departamento de manutenção de urna empresa. Para isso foram realizados uma vasta pesquisa bibliográfica relativa ao gerenciamento de manutenção e à teoria sobre análise organizacional, além de um estudo de caso numa empresa de grande porte. O trabalho apresentado neste artigo serve como piloto e base para estudos futuros. As conclusões, se confirmadas em pesquisas posteriores, poderão subsidiar acomplementação da teoria existente. Publisher: Universidade FUMEC; Belo Horizonte, Brazil; http://www.fumec.br/revistas/index.php Contributor: Cid Gonalves Relation: 1; 2; Revista FACES Journal; 54; 65; 2 Other identifier: 1517-8900 Language: en_AU
2008-04-24
Sodium rare earth diphosphates NaLnP{sub 2}O{sub 7} (Ln = Ce (1), Eu (2)) and polyphosphates NaLn(PO{sub 3}){sub 4} (Ln = Ce (3), Eu (4)) have been synthesized by the high temperature solution reaction. These compounds have been characterized by means of single-crystal X-ray diffraction, elemental analyses, spectral measurements, and theoretical computations. Their structural characteristics are described, and the differences among them are compared. The nature of chemical bonds and electronic origins of optical transitions are analyzed for 1 and 3 in terms of crystal band structures, density of states (DOS), and optical response functions which have been calculated by the DFT method. Results of spectral measurements indicate that crystals 1 and 3 may become promising hosts for ultraviolet-emitting solid-state light sources, and crystals 2 and 4 exhibit the characteristic yellow-red light emission under the excitation of ultraviolet light.
2008-01-01
Sodium rare earth diphosphates NaLnP2O7 (Ln = Ce (1), Eu (2)) and polyphosphates NaLn(PO3)4 (Ln = Ce (3), Eu (4)) have been synthesized by the high temperature solution reaction. These compounds have been characterized by means of single-crystal X-ray diffraction, elemental analyses, spectral measurements, and theoretical computations. Their structural characteristics are described, and the differences among them are compared. The nature of chemical bonds and electronic origins of optical transitions are analyzed for 1 and 3 in terms of crystal band structures, density of states (DOS), and optical response functions which have been calculated by the DFT method. Results of spectral measurements indicate that crystals 1 and 3 may become promising hosts for ultraviolet-emitting solid-state light sources, and ...
2000-03-01
Genetic Algorithms (GAs) are biologically motivated adaptive systems which have been used, with good results, in function optimization. However, traditional GAs rapidly push an artificial population toward convergence. That is, all individuals in the population soon become nearly identical. Niching Methods allow genetic algorithms to maintain a population of diverse individuals. GAs that incorporate these methods are capable of locating multiple, optimal solutions within a single population. The purpose of this study is to test existing niching techniques and two methods introduced herein, bearing in mind their eventual application in nuclear reactor related problems, specially the nuclear reactor core reload one, which has multiple solutions. Tests are performed using widely known test functions and their results show that the new methods are quite promising, specially in real world problems like the nuclear reactor core reload. (author)
1982-07-01
A comparative analysis was made in this work among Pasquill-Gifford (PG) atmospheric dispersion coefficients and those determined at the Juelich and Karlsruhe sites with the purpose of suggesting which one would be the most applicable to the Angra site. Each one of the three systems was determined by different experiments, carried out over sites with diversified features. The systems of Juelich and Karlsruhe were obtained over sites with high surface roughness and from stacks (elevated releases), while the PG system was obtained over sites with a small surface roughness and from ground level releases. The results of the application of these systems at a complex site like Angra,which has a highly diversified structure encompassing sea, vegetation, predominance of light winds and stable stability classes, show that the PG system, the most used in the world, is still the best choice. (author)
2007-07-01
The present rising in the alcohol prices and the Govern intervention trying to avoid the crisis brought to discussion the energy policy for the liquid fuel in Brazil. After a optimism period the present crisis introduce a perspective of a redimension in the expectations to more realistic levels. This article analyses some aspects of the 'crisis' under a more extend vision of the energy policy in a such way to avoid the prevalence of a short term perspective, aborting a short term energy solution more interesting to the country.
1996-07-01
This paper describes an augmented formulation for the solution of the power flux, flexible to the modelling of FACTS (Flexible ac transmission systems) control devices. This formulation uses orthogonal coordinates, however using the same convergence characteristics of polar coordinates. This new methodology is characterized for two additional equations for each bar, and therefore reproducing a easily obtained augmented jacobian matrix. The methodology is tested in the 57 and 118 bars IEEE systems, referring to the New England and South-Southeast brazilian areas, respectively.
2003-08-01
This thesis investigates the application of parameter disturbance methods of analysis to the nonlinear dynamic systems theory, for the study of the stability of small signal of electric power systems. The work is centered in the determination of two fundamental aspects of interest in the study of the nonlinear dynamic behavior of the system: the characterization and quantification of the nonlinear interaction degree between the fundamental ways of oscillation of the system and the study of the ways with greater influence in the response of the system in the presence of small disturbances. With these objectives, a general mathematical model, based on the application of the expansion in series of power of the nonlinear model of the power system and the theory of normal forms of vector fields is proposed for the study of the dynamic behavior of the power system. The proposed tool generalizes the existing methods in the literature to consider effects of superior order in the dynamic model of the power system. Starting off of this representation, a methodology is proposed to obtain analytical solutions of loop back and the extension of the existing methods is investigated to identify and quantify the of interaction degree among the fundamental ways of oscillation of the system. The developed tool allows, from analytical expressions of loop backs, the development of analytical measures to evaluate the stress degree in the system, the interaction between the fundamental ways of oscillation and the determination of stability borders. The conceptual development of the proposed method in this thesis offers, on the other hand, a great flexibility to incorporate detailed models of the power system and the evaluation of diverse measures of the nonlinear modal interaction. Finally, the results are presented of the application of the method of analysis proposed for the study of the nonlinear dynamic behavior in a machine-infinite bus system considering different modeled degrees of the generator and criteria and procedures are proposed to interpret the phenomenon of modal interaction. [Spanish] Esta tesis investiga la aplicacion de metodos de analisis de perturbacion de parametros en la teoria de sistemas dinamicos no lineales, al estudio de la estabilidad de pequena senal de sistemas electricos de potencia. El trabajo se centra en la determinacion de dos aspectos fundamentales de interes en el estudio del comportamiento dinamico no lineal del sistema: la caracterizacion y cuantificacion del grado de la interaccion no lineal entre los modos fundamentales de oscilacion del sistema y el estudio de los modos con mayor influencia en la respuesta del sistema ante perturbaciones pequenas. Con estos objetivos, se propone un modelo matematico general, basado en la aplicacion de la expansion en series de potencia del modelo no lineal del sistema de potencia y la teoria de formas normales de capos vectoriales para el estudio del comportamiento dinamico del sistema de potencia. La herramienta propuesta generalizada los metodos existentes en la literatura para considerar efectos de orden superior en el modelo dinamico del sistema de potencia. Partiendo de esta representacion, se propone una metodologia para obtener soluciones analiticas de lazo cerrado y se investiga la extension de los metodos existentes para identificar y cuantificar el grado de interaccion entre los modos fundamentales de oscilacion del sistema. La herramienta desarrollada permite, a partir de expresiones analiticas de lazos cerrado, el desarrollo de medidas analiticas para evaluar el grado de estres en el sistema, la interaccion entre los modos fundamentales de oscilacion y la determinacion de fronteras de estabilidad. El desarrollo conceptual del metodo propuesto en esta tesis ofrece, por otra parte, una gran flexibilidad para incorporar modelos detallados del sistema de potencia y la evaluacion de diversas medidas de la interaccion modal no lineal. Por ultimo, se presenta los resultados de la aplicacion del metodo de analisis propuesto al estudio del comportamiento dinamico no lineal en un sistema maquina bus infinito considerando diferentes grados de modelado del generador y se proponen criterios y procedimientos para interpretar el fenomeno de interaccion moral.
1989-04-01
A number of methods and products, both hardware and software, to allow data exchange between Apple Macintosh computers and MS-DOS based systems. These included serial null modem connections, MS-DOS hardware and/or software emulation, MS-DOS disk-reading hardware and networking.
Fontes binrias supermoles de raios X
Estuda-se as caractersticas fsicas das fontes supermoles (de raios X (SSS), utilizando dados pticos e em altas energias, no mbito de um trabalho de IC. Trata-se de binrias que apresentam espectro X muito mole, baixas temperaturas e altas luminosidades bolomtricas. Esse sistemas so compostos por uma an branca realizando fuso em sua superfcie, a partir de matria perdida pela estrela companheira. Os resduos de fuso se acumulam na superfcie da an branca, e essa pode ultrapassar o limite de Chadrasekhar, produzir um colapso gravitacional, sendo esse um dos cenrios propostos para as exploses de SN Ia. Apresentamos nesta comunicao o estado da arte das caractersticas fsicas das fontes SSS, situando-as no mbito das VCs. Procuramos tambm situar esses objetos em relao s variveis galcticas V Sge, na medida em que os dois grupos apresentam certas caracersticas bastante semelhantes.A metodologia adotada aquela pedaggico-cognitiva clssica de um trabalho de IC na rea de cincias exatas.
Identificao de radiofontes puntiformes presentes na regio observada pelo telescpio BEAST
Radiofontes extragalcticas so um dos principais contaminantes nas medidas da Radiao Csmica de Fundo (RCF) em freqncias abaixo de 200 GHz. O estudo de seu comportamento espectral permite determinar a contribuio destas fontes s anisotropias intrsincas da RCF. Um dos experimentos recentes concebidos para estudar a RCF o BEAST (Background Emission Anisotropy Scanning Telescope), cujos primeiros resultados foram publicados em fevereiro de 2003. Nos ltimos meses, geramos mapas do cu nas freqncias de 30 GHz e 41 GHz, para um total de 648 horas de observao entre julho e outubro de 2002. Identificamos 4 fontes puntiformes extragalcticas na regio do cu situada entre 0h < RA < 24 h e +32 < DEC < +42, com relao S/R > 4,3 e situadas a pelo menos 25 acima do Plano Galctico. Suas contrapartidas em 5 GHz, segundo o catlogo GB6, so: J1613+3412, J1635+3808, J0927+3902 e J1642+3948. Estas fontes tambm foram identificadas pelo satlite WMAP sendo que trs coincidem com as observadas pelo BEAST dentro da incerteza do feixe do telescpio e a quarta encontra-se bastante prxima (J1613+3412), embora no seja coincidente. As estimativas preliminares de fluxos obtidas para esses objetos so, respectivamente, 0,51; 0,97; 1,08 e 1,6 Jy em 41 GHz. Usando estes resultados e medidas de fluxos em outras frequncias existentes na literatura, apresentamos uma estimativa dos ndices espectrais destes objetos no intervalo de frequncias entre 4,85 GHz e 41 GHz.
Variao temporal do gradiente radial de o/h a partir de uma amostra de nebulosas planetrias
Gradientes radiais de abundncia so observados no disco de nossa Galxia e tambm em outras galxias espirais. No caso da Galxia, o principal problema relativo aos gradientes sua variao temporal, que constitui um dos principais vnculos aos modelos de evoluo qumica da Galxia. As nebulosas planetrias so particularmente interessantes no estudo dos gradientes e suas variaes, tanto espaciais como temporais. So objetos brilhantes, podendo ser observadas a grandes distncias, e tm abundncias relativamente precisas de diversos elementos qumicos. Alm disso, sendo originadas de estrelas com massas entre 0.8 e 8 massas solares na sequncia principal, incluem objetos com idades e populaes diferentes, o que as torna especialmente interessantes ao estudo da variao temporal dos gradientes. Neste trabalho, apresentamos resultados recentes sobre a variao temporal do gradiente de O/H a partir de uma amostra contendo cerca de 200 nebulosas, para as quais obtivemos distncias por mtodos estatsticos. As abundncias foram parcialmente obtidas a partir de observaes em Itajub e La Silla, sendo as restantes obtidas da literatura. Os resultados mostram, pela primeira vez, evidncias de um achatamento do gradiente de O/H, de -0.11 dex/kpc para -0.06 dex/kpc nos ltimos 9 giga-anos ou de -0.08 dex/kpc para -0.06 dex/kpc nos ltimos 5 giga-anos. Esses valores apresentam um bom acordo com alguns modelos recentes para a evoluo qumica da Galxia. (FAPESP/CNPq)
Telescpio de pequeno porte como suporte ao ensino em cidades com intensa poluio luminosa II
Para a maioria dos estudantes, sua passagem pelo ensino formal fundamental envolve a transmisso de fatos que devem ser guardados para um exame, a habilidade para lembrar frmulas e, eventualmente, a repetio de experimentos que devem produzir resultados exigidos pelo professor. O resultado deste modelo de ensino, ao longo dos anos, conhecido por todos: desconhecimento e descontentamento, por parte dos estudantes, de temas relativos ao papel e aos processos da cincia. Acreditamos que a Astronomia, pelo seu carter observacional, uma das reas do conhecimento que pode contribuir neste cenrio. A Fundao Planetrio da Cidade do Rio de Janeiro possui um telescpio Meade LX-200 (25cm) que, juntamente com as cmeras CCD ST-7E e ST8E, tem sido utilizado em projetos voltados aos estudantes do ensino mdio desde o ano 2000. Tais projetos envolvem a conduo de um projeto de pesquisa observacional num nvel apropriado, e possibilitam o contato com tcnicas e novas tecnologias: computador, software para manipulao de dados e grficos, programas de tratamento e reduo de dados, uso de equipamentos ptico-eletrnicos (telescpio e CCD), bem como o processo de aquisio de conhecimento. Dentro da proposta dos anos anteriores, priorizamos projetos de uma noite, ou seja, procuramos trabalhar com fenmenos que apresentem variabilidade com intervalo de recorrncia relativamente curto. Em todos os casos, optamos pela fotometria diferencial, que tem se mostrado bastante eficiente para o cu luminoso como o da cidade do Rio de Janeiro. Neste painel, apresentamos alguns dos projetos desenvolvidos no ltimo ano, com 25 estudantes. Apresentamos os resultados da observao da varivel pulsante AI Vel (V = 6,6) e da varivel cataclsmica FO Aqr (V = 13,5), e do monitoramento do trnsito da lua de Jpiter, Europa, ocorrido em 30 de abril de 2003. As curvas de luz produzidas para as primeiras esto concordantes com as da literatura, assim como os respectivos perodos encontrados (1h20min e 4h48min). No caso do FO Aqr, ficou evidente, tambm, a modulao decorrente da rotao da an branca receptora (21min). O erro estimado de 0,01 magnitude. Propomos uma maior utilizao de telescpios de pequeno porte, como suporte ao ensino (mdio e superior) em cidades com poluio luminosa. Escolas e Planetrios seriam ambientes propcios para a localizao do telescpio. Os critrios adotados na escolha dos objetos e o mtodo observacional empregado so tambm apresentados.
2003-07-01
Sixty-five upland rice cultivars (Oryza sativa L.) were evaluated in relation to gamma-ray sensitivity. Seeds were subjected to seven doses of gamma-radiation and sown in wooden boxes in randomised complete block design with three replications. The experiment was conducted in greenhouse during the year of 1992. Physiological effects caused by radiation in the M{sub 1} generation, were evaluated. The results showed that the sensitivity to the radiation at doses 300 and 360 Gy was useful for distinguishing Indican and Japonica groups. (author)
1992-12-31
This paper shows the aspects related to the water quality and limnology control programs, developed by the Electric Power Company of North Brazil, ELETRONORTE, in three of its water reservoirs: Balbina, Tucurui and Samuel. The ecology of this reservoirs was evaluated at the three phases of the development of a reservoir: river, filling and reservoir 7 refs., 3 figs., 3 tabs.
1996-12-31
The purpose of this paper is to discuss the impact of FACTS (Flexible AC Transmission Systems) devices on the steady-state operation of a generation/transmission system. First of all, a review is made of the main results regarding the impact of FACTS on the steady-state operation. Next we introduce the main FACTS models. The economic-secure operation with such devices is then analysed. Finally, the maximum benefit that can be obtained with a FACTS device is studied with the help of an ideal model. (author) 11 refs., 11 figs., 1 tab.; e-mail: katia at labspot.ufsc.br
1995-12-31
The difficulties in geophysical surveys over the Parecis basin area are discussed. The presence of dense forests, indian preservation areas and private farms make difficult, and in some cases impossible, to acquire geophysical data from land surveys. Previous works in the area have shown the importance of both gravity and magnetics data to define the structural setting of that basin. To allow the continuation of exploratory works in the Parecis basin area, PETROBRAS, the National Oil Company of Brazil, has planned a homogeneous gravity and magnetic coverage on that basin which is, at present, been performed through aerosurveys. The problems involved in field operations as well as the quality control of the data are here discussed. 21 refs., 4 figs
2002-01-01
Recent studies have demonstrated that the infra-red laser can cause alterations in thyroid glands. Their normal activity must be preserved, as they produce the thyroidal hormones triiodothyronine (T3) and thyroxine (T4), that stimulate the oxidative metabolism, essential to maintain a healthy organism. The increase or diminution of these hormones results in alteration of the mitochondria's activity, that determines the secondary effects in the metabolism. The purpose of this study was to evaluate if there was any alteration of the thyroidal hormones plasma levels under irradiation from infra-red laser, with energy density of 4J/cm2, in the region of thyroid glands of male mice. It was concluded that there was an hormonal level alteration statistically significant between the first day of irradiation and seven days after the last ...
1978-01-01
In many countries the discharge of radioactive liquid wastes into the ground is a common practice. The retention capacity presented by soils allows the discharge of bulky amounts of wastes in low and intermediate concentrations, within safety conditions. In addition, operations of ground disposal have advantages in economy and simplicity. However, the possibility of contamination of water resources is important in the site selection for such purpose. In this work, the I.E.A. soil behavior related to the retention capacity of cesium and strontium was studied. Distribution coefficients (Kd) were determined for both elements in function of its concentrations, p H and the presence of K+ and Na+ in the waste solutions. Soil analysis by X-ray diffraction showed the predominance Kaolinite argyle in this region. Soil parameters were also determined in ...
1979-01-01
A stress and strain analysis was made of a scale model of a Prestressed Concrete Pressure Vessel for a Boiling Water Reactor. The aim of this work was to obtain an experimental verification of the calculation method actually used at IPEN. The 1/10 scale model was built and tested at the Instituto Sperimentale Modelli e Structture, ISMES, Italy. The dynamic relaxation program PV2-A and the finite element programs , FEAST-1 have been used. A comparative analysis of the final results was made. A preliminary analysis was made for a simplified monocavity model now under development at IPEN with the object of confirming the data and the calculation method used. (author)
1994-09-01
DOS is an acronym for Disk Operating System. It is actually a set of programs that allows you to control your personal computer. DOS offers the capabilities to create and manage files; organize and maintain information placed on disks; use application programs such as WordPerfect, Lotus 123, Excel, Windows, etc. In addition, DOS provides the basic utilities needed to copy files from one area to another, delete files and list files. The latest version of DOS also offers more advanced features that include hard disk compression and memory management. Basic DOS commands are discussed.
2007-08-10
Plasticized membranes using 1-phenyl-3-(2-thiazolyl)-2-thiourea (PTT) and 1-phenyl-3-(2-thiazolyl)-2-urea (PTU) have been prepared and explored as ytterbium ion-selective sensors. Effect of various plasticizers, viz. chloronaphthalene (CN), o-nitrophenyloctyl ether (o-NPOE), dibutylphthalate (DBP), dioctylsebacate (DOS) and anion excluders, sodium tetraphenylborate (NaTPB) and oleic acid (OA) was studied and improved membrane performance was observed. Optimum performance was noted with membrane of PTT having composition of PTT (3.5):PVC (80):DOS (160):NaTPB (1.5) in mg. The sensor works satisfactorily in the concentration range 1.2 x 10{sup -7} to 1.0 x 10{sup -2} M (detection limit 5.5 x 10{sup -8} M) with a Nernstian slope of 19.7 mV decade{sup -1} of activity. Wide pH range (3.0-8.0), fast response time (10 s), non-aqueous tolerance (up to 20%) and adequate shelf life (12 weeks) indicate the vital utility of the proposed sensor. The proposed electrode comparatively shows good selectivity for Yb{sup 3+} ion with respect to alkali, alkaline earth, transition and rare earth metals ions and can be used for its determination in binary mixtures and sulfite determination in white and red wine samples.
Soft x-ray absorption and scattering from $\\rm Na_x Ca_{2-x} CuO_2 Cl_2$ at x=0.08
2006-03-24
X-ray absorption (XAS) and resonant soft x-ray scattering (RSXS) measurements were carried out on single crystals of doped $\\rm Na_{0.08}Ca_{1.92}CuO_2Cl_2$ (NCCOC) at the $\\rm Cu L_{3/2}$ and $\\rm O~K$ edges. These experiments allow the direct measurement of both the $k=0$ and $k\\neq0$ unoccupied density of states of the $\\rm CuO_{2}$ planes. A mobile carrier peak (MCP) and reduced weight in the upper Hubbard band (UHB) compared to $\\rm Sr_2CuO_2Cl_2$ (SCCO) are observed at this doping, indicating that spectral weight transfer occurs in this system in a manner similar to other doped cuprates. The absence of apical oxygens is seen as a reduced O $p_x$ density of states just above the UHB, which is likely related to the enhanced two-dimensionality of this system. No evidence was seen for a $4a \\times 4a$ density of states (DOS) modulation as reported previously [T. Hanaguri \\emph{et al.}, Nature \\textbf{430}, 1001 (2004)] indicating that this effect is not directly related to DOS modulations in, for example, $\\rm La_{2-x}Ba_xCuO_4$ [P. Abbamonte \\emph{et al.}, Nature Physics \\textbf{1}, 155 (2005)]. This might be explained in terms of glassy electronic behavior or the existence of a surface-nucleated phase transition in NCCOC [S. E. Brown \\emph{et al.}, Phys. Rev. B \\textbf{71}, 224512 (2005)].
2006-07-01
Carrageenan, agaran e alginates are hydrocolloids largely employed in every kind of food products as stabilizing agent and viscosity builder. The human body does not absorb them, so they do not introduce extra calories in the diet. Irradiation is presented as an important alternative method in food preservation because do not induce temperature increase being of good efficiency in cold food ingredients decontamination. In this work aqueous solutions of carrageenan, agar e sodium alginate were gamma irradiated (0-10 kGy) in presence of ascorbic acid, roselle (Hibiscus sabdariffa L.) extract and soy isoflavone. Edible polysaccharide solutions showed to be suitable systems for the evaluation of ionizing radiation effects as they presented a singular radiosensitivity through viscosity changes. The results obtained showed that in general the antioxidants employed had a radioprotective action that can be of importance in the future commercial applications of food irradiation. (author)
2006-01-01
Carrageenan, agaran e alginates are hydrocolloids largely employed in every kind of food products as stabilizing agent and viscosity builder. The human body does not absorb them, so they do not introduce extra calories in the diet. Irradiation is presented as an important alternative method in food preservation because do not induce temperature increase being of good efficiency in cold food ingredients decontamination. In this work aqueous solutions of carrageenan, agar e sodium alginate were gamma irradiated (0-10 kGy) in presence of ascorbic acid, roselle (Hibiscus sabdariffa L.) extract and soy isoflavone. Edible polysaccharide solutions showed to be suitable systems for the evaluation of ionizing radiation effects as they presented a singular radiosensitivity through viscosity changes. The results obtained showed that in general the antioxidants employed had a ...
Time-resolved luminescence from feldspars: New insight into fading
2006-01-01
Time-resolved infrared optically stimulated luminescence (IR-OSL) signals of K- and Na-feldspar samples extracted from sediments were measured in UV, blue and red detection windows, using a fast photon counter and pulsed IR stimulation Formula Not Shown . We observe that the relative contribution of long lifetime Formula Not Shown components in K-feldspars is greater than that in Na-feldspars at each detection wavelength. From any one feldspar sample, red and blue IR-OSL signals have a greater contribution of long lifetime components than UV IR-OSL. We found this long lifetime component was significantly more stable than shorter lifetime components, by comparing natural/regenerated and prompt/delayed time-resolved IR-OSL. We also compared both pulsed and continuous wave (CW) equivalent dos...
2001-01-01
Africanized honeybees are very common insects in Brazil and frequently cause accidents followed by important immunological reactions and even deaths. Their venoms are composed of a complex mixture of substances of general biological actions. Ionizing radiation is able to modify molecular structures affecting the biological properties of proteins. It decreases toxic and enzymatic activities and so, it appears promising as a venom detoxification tool. The main objective of this work was to study the effects of gamma radiation on bee venom, regarding biochemical, pharmacological and immunological aspects. Africanized Apis mellifera whole venom (2 mg/ml) in 0.15 M NaCl solution was irradiated with 2 kGy in a 60Co source. Native and irradiated bee venoms were submitted to high performance size exclusion chromatography (Tosohaas G2000SW column), high ...
2010-01-01
We report ab initio calculations of pressure-induced structural phase transition and electronic properties of the NaCl-type actinide nitrides namely AnN (An=Np and Cm). The total energy as a function of volume is obtained using the self-consistent tight-binding linear muffin tin orbital (TB-LMTO) method by performing spin and non-spin-polarized calculations. Magnetically the AnN compounds are stable in ferromagnetic (FM) state at ambient condition. From the present study, we predict a structural phase transition from ferromagnetic (FM) NaCl-type (B1 phase) structure to ferromagnetic CsCl-type (B2 phase) structure for these in the pressure range of 80.0–50.0GPa. The pressure-induced transition is found to be first order. The band structure and density of states (DOS) are reported in...
2008-01-01
ResumoO estudo do magmatismo do Neocretaceo e Eoterciario na area offshore de Cabo Frio, situada no limite entre as bacias de Santos e de Campos, foi baseado na interpretacao de dados sismicos 2D e 3D processados com o auxilio da Tecnica VA (volume de amplitudes), mapeamentos em terra e no mar e dados de pocos. Os dados sugerem interpretacoes para explicar a genese desse magmatismo, as quais nao levam em conta o modelo classico de plumas mantelicas. O mapeamento dos principais diques alimentadores, em secoes sismicas de reflexao, revelou que eles tem direcao predominante NW-SE, coincidente com o alinhamento da Zona de Deformacao Cruzeiro do Sul, a qual pertence o Alto de Cabo Frio. Essa observacao e coerente com as caracteristicas das falhas de rejeito direcional mais importantes em terra,...
2005-01-01
The medical procedures of diagnosis and treatment that use radiopharmaceuticals generate radioactive wastes that can, after reaching the release limit, follow the conventional ways of collection and disposal of the urban solid wastes. This research aims to detect radiometrically the presence of radioactive wastes in the health-care wastes at the final disposal. It is pointed out that the legal limit for the release of solid wastes established by Brazilian National Commission of Nuclear Energy (CNEN) is 7,5x104 Bq/kg (2 muCi/kg). Measurements in the material of the garbage trucks that make the special collect from Health Service installations are performed, at Belo Horizonte sanitary landfill, using a NaI scintillation counter. Values above the established limit were found in 60% of the cases. The spectral analysis of 6 samples showed the ...
1998-01-01
Prior incubation of the E. coli cultures with the iron ions chelator 2,2'-dipyridyl (1 mM) caused an intensification of the lethality and the mutagenesis induced by the hydrogen peroxide, mainly at high concentrations (20 mM). It was also detected an enhancement of DNA strand breaks in this condition. The addition of the copper ions chelator neocuproine blocked partially this phenomenon. The enzymes XthA and Nfo act alternatively in the repair of the lesions induced by H2O2 in the presence of 2,2'-dipyridyl. H2O2 can act synergistically with neocuproine in killing E. coli, causing an enhancement in DNA strand breaks. The recombinational repair, the UvrABC excinuclease and Fpg function appeared to participate in the repair of the synergistic lesions. (author)
2006-01-01
The objective of this work was to study the role of aerosols in modifying clouds and precipitation. This is one of the most difficult aspects in the study of climate changes. Field measurements of cloud condensation nuclei (CCN) and cloud size distributions performed during the Large Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) campaign revealed distinct characteristics between clean and polluted atmospheric conditions. Measurements were conducted over the southwestern Amazon region during September-October 2002 focusing the transition from dry to wet seasons. During this period, analysis of CCN concentrations in the boundary layer revealed a general decreasing trend from mean values higher than 1200 cm-3 to values lower than 300 cm-3. The comparison between clean and polluted areas showed CCN concentrations 5 times higher than in polluted ...
Neste trabalho apresentamos imagens de alta resoluo angular da regio HII gigante G333.1-0.4 obtidas atravs dos filtros J, H e K no telescpio de 4-m do CTIO. Este trabalho faz parte de um estudo de regies HII gigantes no infravermelho prximo que tem por objetivo estudar a natureza da formao de estrelas massivas e traar a estrutura espiral de nossa galxia. Nossa determinao da distncia baseada no mtodo da paralaxe espectroscpica de estrelas OB localizadas na seqncia principal de idade zero (ZAMS) do Diagrama HR. No caso de G333.1-0.4, a magnitude aparente das estrelas localizadas na ZAMS indica que a distncia no pode ser maior do que o limite inferior determinado por tcnica rdio (2,8 kpc). Resultados semelhantes foram encontrados para regies estudadas anteriormente, reforando a idia de que a taxa de formao estelar na Via Lctea menor do que o determinado a partir de dados rdio. Nossos resultados mais recentes sobre o contedo estelar de G333.1-0.4 revelaram vrios objetos que possuem cores bastante avermelhadas (H-K > 2,0). Ns identificamos estes objetos usando os diagramas cor-cor e cor-magnitude dos aglomerados. Estes objetos apresentam um forte excesso em emisso na banda K e possivelmente se tratam de estrelas do tipo OB envolvidas por um disco/envelope circumestelar espesso. O estudo da funo de massa inical desta regio, em conjunto com resultados de nossos trabalhos anteriores, aponta para uma IMF independente da posio galtica. A contagem de estrelas nos fornece um valor para o nmero de ftons no contnuo de Lyman que corrobora com a afirmao de que G333.1-0.4 se encontra mais prxima da menor distncia determinada por rdio.
Local Phonon Density of States in an Elastic Substrate
2004-01-01
The local, eigenfunction-weighted acoustic phonon density of states (DOS) tensor is calculated for a model substrate consisting of a semi-infinite isotropic elastic continuum with a stress-free surface. On the surface, the local DOS is proportional to the square of the frequency, as for the three-dimensional Debye model, but with a constant of proportionality that is considerably enhanced compared to the Debye value, a consequence of the Rayleigh surface modes. The local DOS tensor at the surface is also anisotropic, as expected. Inside the substrate the local DOS is both spatially anisotropic and non-quadratic in frequency. However, at large depths, the local DOS approaches the isotropic Debye value. The results are applied to a Si substrate.
O objetivo deste artigo é relatar a experiência do Comitê de Ética em Pesquisa da Secretaria de Estado de Saúde do Distrito Federal (CEP/SES/DF) Brasil, durante o período de 10 anos a partir de sua fundação. Trata-se de uma avaliação descritiva e documental, na modalidade estudo de caso, utilizando-se a totalidade de projetos protocolados no CEP/SES/DF (N° 052/08) nesse período.As pendências mais freqüentes dos projetos foram: termo de consentimento livre e esclarecido (30%), folha de rosto (25%), metodologia (20%), curriculum vitae (12%), planilha de orçamento (9%), outros (4%).O relato das atividades do CEP/SES/DF no período de 10 anos revelou, através de sua produtividade, a legitimidade do processo de análise ética dos protocolos visando à proteção dos participantes da pesquisa.
The intergranular corrosion of Ni-base alloy 600 surface melted by a CO{sub 2} laser beam
2000-02-01
The effects of laser surface melting (LSM) on the intergranular corrosion of the sensitized Alloy 600 were studied by the double loop electrochemical potentiokinetic reactivation (DL-EPR) method in de-aerated 0.01 M H{sub 2}SO{sub 4}+10ppm KSCN solution at a scan rate of 0.5 mV/sec at room temperature. C-ring test was performed to confirm the effects of sensitization treatment on the fracture mode of Alloy 600 in 0.1 M Na{sub 2}S{sub 4}O{sub 6} solution. The degree of sensitization(DOS) of the sensitized Alloy 600 measured from the DL-EPR curves was considerably reduced by LSM. The sensitized Alloy 600 after LSM also exhibited a relatively high resistance to intergranular corrosion, compared to the sensitized Alloy 600 without LSM. The cause of high resistance to intergranular corrosion of the laser treated Alloy 600 was analyzed and compared with that of the non-laser treated Alloy 600 by observing the microstructural changes during the LSM process, especially by examining the difference in the precipitation behaviors of grain boundary Cr-rich carbides in both alloys. The resistance to intergranular stress corrosion cracking of the laser treated Alloy 600 in sulfur-bearing environments was also discussed from the results of measured DOS and microstructural examination. 14 refs., 7 figs., 1 tab.
2003-12-19
Plasticizer-free methyl methacrylate-decyl methacrylate (MMA-DMA) microspheres were prepared under mild, non-reactive conditions using a high-throughput particle generator. The particles were perfectly smooth and monodisperse, with a particle diameter of approximately 10.0 {mu}m. In order to evaluate the suitability of the polymer as a matrix for bulk extraction processes, lipophilic sensing components were incorporated into the particles. Particles contained either a H{sup +}-selective chromoionophore (ETH 5294) only (type 1), or a K{sup +}-selective ionophore (BME-44), anionic sites (NaTFPB), and ETH 5294 (type 2). Type 1 particles responded according to an anion-proton coextraction mechanism and demonstrated Hofmeister selectivity by showing a preference for more lipophilic sample anions (ClO{sub 4}{sup -}>NO{sub 3}{sup -}>Cl{sup -}). Particles of type 2 functioned by way of an ion-exchange equilibrium and demonstrated a functional response for K{sup +}, with a dynamic range from 10{sup -1}-10{sup -4} M K{sup +}. These particles also exhibited selectivity comparable to that previously reported for analogous particles made from bis(2-ethylhexyl sebacate) (DOS)-plasticized poly(vinyl chloride) (PVC) and DMA-DOS. In addition, the behavior of both types1 and 2 particles was in agreement with analogous thin film optical sensors (optodes) prepared from MMA-DMA. With the advent of ionophore-based plasticizer-free microspheres a wide variety of ions may potentially be assessed using various popular bead-based sensing strategies, such as lab-on-a-chip technologies, bundled optical fiber arrays, and flow cytometry, without experiencing the deleterious effects resultant of plasticizer leaching.
Lithostratigraphy of the Grao Para Group, Serra dos Carajas, Brazil
1985-01-01
The Grao para Group (GPG) is the low-grade metavolcanic portion of the largest metasupracrustal fold belt of the eastern Guapore Shield. It hosts the enormous Serra dos Carajas banded iron formations and was considered to be Early Proterozoic in age. Roughly 4-6 km of metavolcanic rocks underlie 300-400 m thick BIF, and more mafic volcanics overlie them. Subalkaline basalts, basaltic andesites and shoshonites predominate. The basalts and andesites have higher K/sub 2/O (1.5-3.0%) than is typical of Archean greenstone belts, and have LREE-enriched patterns. Spilitic alteration, yielding extreme K/Na ratios, is only locally apparent. The chemical compositions of the volcanics, their bimodal character, and isotopic signatures are consistent with their eruption through continental or transitional crust. The surrounding region contains rocks that may comprise an older, more typical Archean greenstone-granite gneiss terrane. Stratigraphic relations with the overlying sandstones, conglomerates, shales, cherts and carbonates require further work. In areal extent and apparent supracontinental setting, the Carajas iron deposits are like Lake Superior and Hamersley deposits; in age and direct association with volcanic rocks they are like Algoma-type sequences. The GPG has analogies with some Proterozoic belts in SW USA, and with younger continental rift deposits. It is also similar to some of the youngest shoshonite-bearing sequences in the Superior Province, but other Archean examples are rare.
1989-07-01
This study evaluates the environmental problems caused by the mining works of coal, peat and oil schists; also it evaluates the kind of treatment used by the mining companies against water, air and ground pollution, as well as the necessary control according to the mine activities and the affected environment. the studied areas are situated at brasilian states of Santa Catarina (Criciuma, Urussanga and Sideropolis), Rio Grande do Sul (Charqueada, Bage, Cachoeira do Sul, Butia and Arroio dos Ratos), Parana (Figueira and Sao Mateus do Sul), and Sao Paulo (Iguape and Sao Jose dos Campos). This study was done through a direct inquiry, by sending questionnaire to fifteen coal mining companies, three of peat ones and one of oil schists one. besides it was done a compilation of federal and state laws concerning to the environment and on the rights and duties of the mining companies. The information brought up in this way were compiled into a data bank, which allowed and sample surveys of environmental condition in the different industries and further it enabled a comparison between the real facts and the bibliography suggestions about adequate monitoring of the air, waters and ground, during mining activities. this analysis showed that the environment problems, created by the three former kind of mining works, are under control through projects of environment restoring and monitoring in phase of implantation and that these projects are restricted to that less expensive and easier to construct (holding back in pools or reservoirs, pouring in pits and aspersion). It was not notices a significant monitoring of parameters considered to be critical to the environment (metals, cyanides, sulphide and general bacteria). Almost all the companies have not yet exact data about the efficiency of each kind of environmental treatment because it is new ones and are just in follow-up and consequently they have not yet parameters to change the adequate the steps of the treatment, because of lack of information. Any way it is not a justification to the present condition of environment control of these companies, just because its of their responsibility the consequences of their producing activities. (author)
1985-03-01
On April 14 and December 18, 1981, two balloon flights were performed from Sao Jose dos Campos, Brazil (geographic coordinates 23 deg 12 sec S, 45 deg 51 sec W and L approximately 1.13), each carrying an omnidirectional NaI(Tl) scintillation crystal, in order to measure bremsstrahlung X-rays due to energetic electron precipitation in the atmosphere of the South Altantic Magnetic Anomaly (SAMA), as well as to look for their relationship with geomagnetic activity. Since the April flight occurred during a time interval with an intense geomagnetic activity (the absolute value of Dst is approximately 290) whereas the December flight was conducted during a geomagnetically calm period (the absolute value of Dst is approximately or equal to 35), a comparison between these measurements shows an intensification of about .005 photons/sq.cm. sec.KeV at an atmospheric altitude of 5.5 gr/sq. cm.2 and for an energy interval of 30 to 150 KeV. This type of X-rays intensification, observed for the first time at balloon altitudes of the SAMA, is claimed to represent a direct evidence of enhanced energetic electron precipitation in association to the intensification of geomagnetic activity.
The structural, electronic, elastic, vibrational, and thermodynamic properties of HoX (X=Sb, Bi)
2010-01-01
We have predicted the structural, electronic, elastic, vibrational, and thermodynamic characteristics of HoX (X=Sb, Bi) compounds in NaCl type (B1) structure through the method of density functional theory within the generalized gradient approximation (GGA) using Vienna Ab initio Simulation Package (VASP). Specifically, the lattice constant, bulk modulus, pressure derivative of bulk modulus, cohesive energy, second-order elastic constants, Young’s modulus, isotropic shear modulus, Zener anisotropy factor, Poisson’s ratio, electronic band structures, and related total density of states (DOS) have been calculated and compared with the available experimental data. The spin–polarization (SP) and spin–orbit coupling (SOC) have been taken into account for the elec...
2008-07-01
Due to the fact that, the workers' behavior is characterized by its complexity and diversity, this issue has been seen as a great 'black box' in discussions regarding the Management Systems of SHE. Associated with this issue other arises: How conscious people? How to engage them with the process? How to improve the risk control? How to motivate the prevention? Most of these responses are discussed in the Social and Human Sciences for many years. However, it is necessary to closer the technical-operational knowledge and the human aspects, applying in the organizations' daily work, to make the working environment more safe. The purpose of this study, therefore, is examining the possibility of reducing accidents through the identification and treatment of deviations (unsafe acts and unsafe conditions), cause the whole accident, be it serious or not, begins with a small deviation. It was used as a reference tool, the Behavior audit and it is based on field's observations, applied into a production unit of a large petrochemical industry in northern Brazil, during the years 2006 and 2007. (author)
2006-01-01
In this work was studied the influence of the addition of 0.5 at. % of zirconium and gallium on praseodymium-based HD sintered magnets obtained using a mixture of alloys. The alloys used in this study were: Pr12.6Fe68.3Co11.6B6Zr0.5Ga1, Pr16Fe75.5B8Zr0.5, Pr13Fe80.5B6Zr0.5. The investigation started by measuring the magnetic properties and observing the microstructure of the magnets. After that, the magnets were annealed at 1000 deg C for 2 hours followed by rapid cooling, in a total of 10 hours. This heat treatment was followed by 5 hours at the same temperature up to a total of 35 hours. Changes in the microstructure were compared to the change in the magnetic properties aiming at a proper ...
2004-01-01
Several studies have shown the negative effects of surfactants, as detergents active substance, when discharged on biological sewage wastewater treatment plants. High toxicity may represent a lower efficiency for biological treatment. When surfactants are in aquatic environment they may induce a loss of grease revetment on birds (feather). Depending on the surfactant concentration, several damages to all biotic systems can happen. Looking for an alternative technology for wastewater treatment, efficient for surfactant removal, the present work applied ionizing radiation as an advanced oxidation process for affluents and effluents from Suzano Treatment Station. Such wastewater samples were submitted to radiation using an electron beam from a Dynamic Electron Beam Accelerator from Instituto de Pesquisas Energeticas e Nucleares. In order to assess this proposed ...
2005-01-01
In the present work, the multi-gamma emitters 166mHo and 72Ga have been measured by 4pibeta-gamma coincidence technique. The calibration system is composed of a 4pi gas-flow proportional counter coupled to a pair of NaI(Tl) crystals. Both radionuclides were measured by using two gamma discrimination windows, namely (629.9 + 834.2) keV and (2201.6 + 2507.7) keV for 72Ga and 184.4 keV and (711.7 + 830.5) keV for 166mHo. The methodology recently developed by LMN (Laboratorio de Metrologia Nuclear) for simulating all detection processes in a 4pi(beta,X)-gamma coincidence system by means of the Monte Carlo technique was applied to the measurements of both radionuclides, and the predict behavior extrapolation curve was compared with the ...
2000-01-01
The lifetime decrease of Er3+ (4I13/2, 4I11/2 and Ho 3+ (5I6, 5I6) levels were investigated in YLF crystals doped with Tb3+, Eu3 and Nd3+ deactivator ions. The critical radius of interaction were determined using the overlap integral method. Each multiplet contribution of the deactivator ion in the nonradiative energy transfer process was determined. Although the microscopic parameters have indicated that Tb3+ and Eu3+ ions introduce strongest deactivation effects in the first excited state of activators, it was concluded that Nd3+ ion is the best deactivator to be used in Er- and Ho-doped YLF. This conclusion was based on the fact that Nd3+ should introduce ...
2006-01-01
Brazil has a long tradition in thorium technology, from mineral dressing (monazite) to the nuclear grade thorium compounds. The estimate reserves are 1200,000. ton of ThO2. As a consequence from the work of thorium purification pilot plant at Instituto de Pesquisas Energeticas e Nucleares-CNEN/SP, about 25 ton of a sludge containing thorium and rare earths was accumulated. It comes as a raffinate and washing solutions from thorium solvent extraction. This sludge, a crude hydroxide named RETOTER contains thorium, rare earths and minor impurities including the radiogenic lead-208, with abundance 88.34 %. This work discusses the results of the studies and main parameters for its recovery by anionic ion exchange technique in the hydrochloric system. The isotope abundance of this lead was analyzed by high resolution mass spectrometer (ICPMS) and thermoionic mass ...
1988-12-31
In the specialized literature about the use of extra oral forces in the treatment of the Class II malocclusion one can observe that it has been used more and more, with the objective of achieving teeth improvement and bone as well. It is proposed to evaluate the extent of the orthodontic/orthopedic modifications and their influence in the facial pattern of patients with those malocclusions, treated during the mixed dentition period. A sample of 32 patients of both sexes, leucoderms, with Class II, division I malocclusion, between 7 and 14 years old, were studied employing a cephalometric radiographic method for evaluation. (author). 94 refs., 11 figs., 15 tabs.
1988-01-01
In the specialized literature about the use of extra oral forces in the treatment of the Class II malocclusion one can observe that it has been used more and more, with the objective of achieving teeth improvement and bone as well. It is proposed to evaluate the extent of the orthodontic/orthopedic modifications and their influence in the facial pattern of patients with those malocclusions, treated during the mixed dentition period. A sample of 32 patients of both sexes, leucoderms, with Class II, division I malocclusion, between 7 and 14 years old, were studied employing a cephalometric radiographic method for evaluation. (author). 94 refs., 11 figs., 15 tabs
2009-01-01
Objective: To assess the role of proton magnetic resonance spectroscopy and dynamic contrast-enhanced magnetic resonance imaging in the differentiation between malignant and benign musculoskeletal tumors. Materials And Methods: Fifty-five patients with musculoskeletal tumors (27 malignant and 28 benign) were studied. The examinations were performed in a 1.5 T magnetic resonance scanner with standard protocol, and single voxel proton magnetic resonance spectroscopy with 135 msec echo time. The dynamic contrast study was performed using T1-weighted gradient-echo sequence after intravenous gadolinium injection. Time signal intensity curves and slope values were calculated. The statistical analysis was performed with the Levene's test, followed by a Student's t-test, besides the Pearson's chi-squared and Fischer's exact tests. Results: Proton magnetic ...
Pressure-induced structural transition in PuTe
2009-01-01
The structural stability, electronic and optical properties of PuTe under high pressure are investigated by using density functional theory (DFT), in the presence and absence of spin-orbit coupling (SOC). There exists a structural phase transition from NaCl-type (B1) structure to CsCl-type (B2) structure at the transition pressure of 14.8 GPa (without SOC) and 31.7 GPa (with SOC). The electronic density of states (DOS) show that the f-electrons of Pu are more localized and concentrated in a narrow peak near the Fermi level. The band structure shows B1-PuTe is metallic. A pseudogap appears around the Fermi level of the total density of states of B1 phase PuTe, which may contribute to its stability. The calculated reflectivity R(omega) shows agreement with the available experimental results
2004-07-01
The use of Natural Gas is nowadays increasing in Brazilian scene and this fact shows the necessity of effective planning tasks in that sector. In the case of Natural Gas Vehicular (NGV) distribution one can face problems of actor's (distributor, retailers, customers and non-users) point of view conflicts and fuel stations expand in most Brazilian urban areas in an uncontrolled way, despising counties regulation on land use. This paper reports a study using a model based in Game Theory concepts to determine some key-variables as the number of fuel stations which must deliver NGV in a given study area. Although some information could not be available the results of simulation shows the usefulness of using such an approach to give solutions to distribution questions in NGV sector. The model was applied to the case of a district in Fortaleza city which is the study area of a project entitled Projeto GASLOG presently on process under the sponsoring of Brazilian Government, PETROBRAS and Brazilian GasEnergy Research Network. (author)
2008-07-01
The Brazilian environmental law requires oil companies' commitment to implement environmental programs, among which the environmental education project. This type of project should be understood by the companies as an opportunity for the development of socio environmental responsibility policies towards the affected populations. In order for the environmental education project to be effective as a means of awareness and social transformation, it is required to increase public's participation from the process of knowledge creation on the communities environmental problems to the disclose of the produced contents. This work refers to the use of the audiovisual as an instrument for the mobilization and consciousness for the construction of participative diagnostics, from the experience of the Environmental Education Project of the Polvo field, accomplished in ten municipal districts of the Campos Basin region. Inspired on an original methodology, the project promoted environmental cinema workshops that resulted in 30 documentaries directed by the local population and 10 environmental forums in which were developed local audiovisual environmental agendas. (author)
2001-07-01
The signal to noise ratio (S/N) of radiographic film images may be optimized if the thicknesses and atomic composition of the structures to be analyzed are known. With specifications and a knowledge of the interaction of photons with the materials, the photon energy for maximum contrast may be determined. We propose a K-edge filter in addition to the normal aluminum filter, to reduce the dose to the patient by the transmission of a narrow spectrum of photons with energies to optimize the image contrast. The optimum photon energy to obtain the best contrast between dental pulp and dentine and between dentine and dental enamel was determined to be 29-34 and 22-26 keV respectively. The filter material, which closely approximates these spectra, is made of Ce (Z=58) whose thickness is shown do depend on the parameters of the X-ray generator. (author)
2003-01-01
During the development of applications of high intensity lasers in the enamel and dentine, adverse thermal effects into the entire dental structure, including the pulp, must be verified. The measurement of the temperature in the intact pulp, however, is not a solved problem. For this purpose, models have been used frequently, using extracted teeth, with pulpal cavities filled with materials that simulate only thermal properties of the pulp. Current models, however, do not simulate optical properties of the pulp, not taking the remaining radiation in the pulp chamber into account. The aim of this study was to verify if the remaining radiation from neodymium and diode lasers that reach the pulp chamber, at the models using extracted bovine teeth, can cause local thermal effects. For this purpose, two models were developed, using extracted bovine teeth with their pulp chambers ...
1990-01-01
Cobalt or Nickel promoted molybdenum or tungsten catalyst with alumina or silica-alumina as support are commonly used in the hydro treatment processes. Hydrotreatment catalysts used in the mild hydro cracking processes (MHC) use alumina, fluorine enriched alumina or silica-alumina. In hydro cracking processes usually zeolite is used as a support. The active form of these supported metals is their sulphides. The maintenance of the sulphide form of these catalysts in industrial reactors has to do with an adequate H{sub 2} S/H{sub 2} relation in the gas phase, which in turn is a function of the treated feed and the operational conditions used. Minimum values in the H{sub 2} S/H{sub 2} versus temperature relation were obtained through reduction equilibrium diagrams of these sulphides. Typical values of H2 S content in the various HDT units of PETROBRAS are presented for comparison with the adequate theoretical values. (author) 7 refs., 4 figs., 3 tabs.
2010-01-01
Resumo Conchostraceos fosseis sao abundantes e relativamente diversificados na Formacao Rio do Rasto (Grupo Passa Dois, Bacia do Parana, sul do Brasil), porem leaiideos (`Leaia pruvosti' [Reed, F.R.C., 1929. Novos Phyllopodos Fosseis do Brasil. Boletim do Servico Geologico e Mineralogico do Brasil 34, 2-16]) foram anteriormente encontrados numa unica localidade da formacao no norte do Estado de Santa Catarina. Novos especimes da Familia Leaiidae, coletados em dois afloramentos no centro do Estado do Parana, proximo ao topo da formacao, estimularam a revisao dos taxons relacionados. Os novos leaiideos e aqueles previamente conhecidos sao aqui classificados como Hemicycloleaia mitchelli [Etheridge Jr., R., 1892. On Leaia mitchelli Etheridge. Proceedings of the Linnean Society of New South Wa...
2002-01-01
Pb, Rb, Sr, Sm and Nd isotope analyses were carried out on amphibolitic rocks from Campo Largo (PR), Rio Branco do Sul (PR) and Adrianopolis (PR) and for the metabasite from Adrianopolis and Apiai (SP), all belonging to the Acungui and Setuva Groups, southern portion of the Ribeira Belt. These occurrences were chosen because each exhibits geochemical data indicative of a mantle source, having different signatures. Geochronologic determinations are available only for the Apiai metagabro with Neoproterozoic ages of 617 +- 4 Ma (U/Pb in zircon) and 839 +- 85 Ma (Rb/Sr, whole rock). Age determinations by Sm/Nd mineral isochron using whole rock, plagioclase and pyroxene yield values of 885 +- 53 Ma for the Apiai metagabro and 820 +- 84 Ma for the Adrianopolis metabasite. These results agree within error with the Rb/Sr isochron of 839 +- 85 Ma may possibly be interpreted as the time of ...
Integrated geophysical investigation of a possible new alkaline occurrence in SE Brazil
2005-01-01
ResumenO levantamento aerogeofisico SP-RJ do Servico Geologico do Brasil (CPRM) evidencia uma anomalia magnetica, sem correspondentes geologicos em superficie, mas com caracteristicas semelhantes aquelas produzidas por complexos alcalinos que afloram na mesma area. Esta observacao induziu a utilizacao de diferentes metodologias geofisicas para caracterizar sua fonte. Sao apresentadas imagens de satelite para diferentes bandas espectrais, resultados de sondagens sismicas, levantamento gravimetrico e correspondente magnetico em superficie ao longo de um perfil que corta a anomalia, e medidas de densidade e susceptibilidade das diferentes litologias da area. Todas as informacoes obtidas foram utilizadas como vinculos para a modelagem direta simultanea dos dados gravimetricos e magneticos de s...
2008-07-01
Steam injection is the most used method of additional recovery for the extraction of heavy oil. In this type procedure is common to happen gravitational segregation and this phenomenon can affect the production of oil and therefore, it should be considered in the projects of continuous steam injection. The effect of gravity causes the segregation of fluids inside the porous media according to their densities. We know that the gravitational segregation can happen in almost every case where there is injection of light fluid, specially steam, and occurs with greater intensity for viscous oil reservoirs. This work discusses an optimization of some operational parameters as flow rate steam, distance between the wells (injector-producer), and interval of completion, which contributed to the reduction of gravity override, in a numerical model that shows the phenomenon with greater intensity. It was made an analysis of technical and economical viability of an optimized model. The analysis was performed using the simulator of CMG (Computer Modeling Group) - Stars 2007.11, in which it was observed the influence of operational parameters in heavy oil reservoirs with similar characteristics to Brazilian Northeast. (author)
2010-01-01
The reference condition established to determine the absorbed dose in water of a linear accelerator, according to Tars-398, depends on some electro-mechanics parameters. Furthermore, in principle, uncertainties in the parameters settings may results in dosimetry variations. The goal of this study is to analyze the influence in quality control parameters changes, which tolerance limits are established by TECDOC-1151, in the dosimetry result of photon beam. For this, some parameters (gantry and collimator angle, field size and source to surface distance) and chamber position were changed. The results of these changes were evaluated. For the variation range of quality control items (that went beyond the tolerance limits established by TECDOC-1151), the deviations got less than 1 % of reference for all analyzed parameters. The deviations for the ionization chamber ...
2005-01-01
Objective: To evaluate the prevalence and appearance of incidental paranasal sinuses abnormalities in children with no clinical evidence of rhino sinusitis using CT scans. Materials and methods: CT scans of the head or orbits of children between 0 and 18 years of age performed due to problems not related to rhino sinusitis were studied. Results: Sixty-four children were included (mean age 5.7 years. Standard deviation = 3.9). Incidental sinuses abnormalities were found in 46 cases (72%). In most cases the abnormalities were mild (25/46) and mucosal thickening was the most common finding. Complete opacification and fluid levels occurred in 12 children. More than one cavity was affected in 33 patients and abnormalities were most frequently seen in maxillary sinuses, followed by ethmoid sinuses. Bilateral and symmetric findings were common. The prevalence and intensity of ...
2008-07-01
This paper aims to clarify and understand the reasons for the current economic policy and trade between Bolivia and Brazil, the latter represented by PETROBRAS, as the year 2006. Focuses on the regulatory change in Bolivia that culminated in a period of re-nationalization of its mineral wealth as opposed to international interests, including Brazilians, and agreements entered into during the opening of the market in the country. Thus, set in the Latin American actual situation, we undertake to understand the process and its consequences for Brazil, which, even with the third largest gas reserves in the region, in the short term, it follows as an importer of this feature. To have a concrete base with foundations and analyze what happens today, we must understand the political history of Bolivia and their internal changes. So we divided the work into two parts: first, we analyze the neo liberal period, and the agreements signed with Brazil in the hydrocarbon sector, for mutual benefits. In the second part, we understand the political rise of Evo Morales and the nationalization process of national wealth and the consequent crisis that developed with the international oil companies, especially with PETROBRAS, to the final outcome on the price, production and export of gas.
2004-01-01
Impact of the nutrients N and K and soluble sugars on Diabrotica speciosa (Germar) (Coleoptera, Chrysomelidae) and Agrotis ipsilon (Huefnagel) (Lepidoptera, Noctuidae) populations in potato crops, Solanum tuberosum L. (Solanaceae). The occurrence of Diabrotica speciosa (Germar, 1824) and Agrotis ipsilon (Huefnagel, 1767) on the potato cultivars Achat and Monalisa, influenced by nitrogen and potassium dosage, and minimum quantity of soluble sugars, was studied. The following parameters were evaluated: concentration of mineral nutrient and sugar in green leaf, senescent leaf, leaf in abscission, stem, tubercle and total plant using extracts of infusion in ethanol 80%. The largest infestation of D. speciosa larvae was on Monalisa cultivar at 150 kg.ha-1 of N + K with 27.03% at P
1990-01-01
The evaluation of introducing or diffusing new technologies at a macro economic level using micro economic information can be carried out through the careful selection of a small number of homogeneous groups of plants from the point of view of the main technical parameters being considered. In this paper this concept is applied to the study of cogeneration in sugar and alcohol producing plants. The statistical techniques of Cluster Analysis, regressions and mean value testing are used. Basic cogeneration plant designs are proposed for alternatives development scenarios for this industrial branch. These scenarios are based upon differing assumptions about the expansion of alcohol market, use of surplus sugar cane bagasse as saleable commodity, as a fuel or raw material, and price expectations for the sale of surplus power from the cogeneration plants to the local grid. ...
2005-07-01
The work searches into the hazard and the weakness which involves the community around the radioactive waste final disposal, localized in Abadia de Goias municipality, Goias state, Brazil. In order to obtain a deep knowledge on the characteristic hazards of the modernity, the sociological aspects under discussion has been researched in the Anthony Giddens and Ulrich Beck works. The phenomenon was analyzed based on the the subjective experiences of the residents, which live there for approximately 16 years. This temporal analysis is related to the social impact suffered by the residents due to the radioactive wastes originated from the radiation accident with 137 cesium in Goiania, GO, Brazil, in 1987. In spite of the local security, they identified the disposal as a hazard source, although the longer time residents have been better adaptation. The weakness of the local is significant by the proximity of residences near the area of the radioactive waste final disposal. (author)
1996-08-01
The radioactive wastes from Goiania`s accident, with be deposited at the repository site of Abadia de Goias, located 20 km away from the city of Goiania. This paper presents a groundwater flow in confined or unconfined, heterogeneous and anisotropic porous media with variable layer thicknesses. The necessary parameters to simulate the flow were taken from technical reports and from specific studies about the region. The geological and hydrogeological studies evidence that in this area there is one aquifer type water table. The permeability coefficient evaluated for aquifer formation was 1.88x10{sup -4}cm/s and for the porosity 0.47. The average annual rate of recharge was evaluated in 0.22 m. The potentiometric map generated using the MODFLOW code showed a good a agreement between the hydraulic head simulated and that measured in the field. (author) 8 refs., 3 figs.
2001-07-01
The fertilizer contribution to radio uptake by tomato plants was assessed. Tomato and soil samples from four different plantations were analyzed: two using organic fertilizer and two using phosphate fertilizer. The Ra concentrations in eight of the most used tomato fertilizers were determined. The concentration values ranged from 14 to 221 Bq/kg of Ra-226 and from 25 to 176 Bq/kg of Ra-228. Owing to the low Ra concentration and to the used fertilizer quantities, the fertilizers would not increase significantly the Ra soil concentration. However, the highest soil to plant concentration ratios were found in the plantations using phosphate fertilizers. This outcome pointed out the higher Ra availability in the phosphate fertilizer plantations than in the organic fertilizer plantations, showing a possible positive influence of phosphate fertilizers for the tomato Ra uptake. Due to the phosphate fertilizer used, the dose could increase from 0,05 Sv/year to 0,24 Sv/year. However this increase is not significant face the ingestion average worldwide effective dose. (author)
2004-07-01
The shelf life of fruits and vegetables can be directly related to store temperature. At determined temperature and humidity a better conservation of the product can be achieve. The cold chain delays the aging, having its conservation guaranteed until the consumer. It was carried through in the Terminal Warehouse of Sao Paulo- CEAGESP, a research for evaluation of the condition of the cold chambers used. The cold storage equipment evaluation was measured using the follow parameters: temperature, humidity, isolation, type of equipment used, etc. It was analyzed, chambers used for cold storage, using thermal load calculation. Apple and pears were the most stored commodities in CEAGESP, 50 % and bananas the second one (31,4%). Based in the average volume of commercialization, it was observed that 57% of the motors were over dimensioned. (author)
1996-12-31
The behaviour of the static recrystallization between passes in hot deformation schedules of a vanadium micro alloyed medium carbon steel was studied. The samples were tested under continuous cooling conditions, on a computerized torsion machine with various combinations of strain, strain rate and inter pass times, after reheating at 1150 deg C. Using mean flow stress versus 1000/T diagrams, the effect of the deformation conditions on the non-recrystallization temperature Tnr, the temperature at which recrystallization no longer completes, was determined. It increases with increasing strain and decreases slightly with increasing strain rate. Also, it was observed that Tnr shows a minimum for inter pass times around 30 seconds, which may be correlated with the transition of the recrystallization rate controlled by solid solution to precipitation. (author) 4 refs., 10 figs., 1 tab.
2006-01-01
Objective: In the pediatric group, the radiological diagnosis of bone tumors of the hip is difficult and presents some peculiarities, but reviewed literature does not approach this specific problem. The objective of the present study was to investigate the existence of reliable radiological patterns for the differential diagnosis of these tumors. Materials And Methods: Radiological findings of bone tumors of the hip in ten patients in the age range between 8 and 19 years have been reviewed. Results: Bone reaction (sclerosis or lysis), periosteal reaction (lamellar with single or multiple layers, or radial), tumor extent in the bone and level of soft tissues invasion have presented low specificity. Soft tissue calcifications, when considered as a whole, were non-specific. However, when those calcifications with varied shapes and sizes, nearby the affected bone (pattern ...
2005-01-01
Purpose: To study the imaging exams more commonly used for abdominal aortic aneurysms evaluation - ultrasonography, conventional computerized tomography, helical computerized tomography and nuclear magnetic angio resonance - comparing the preoperative measurements reached by those radiological methods with the measurements made during the surgical procedures. Methods: Patients who had indication of elective transperitoneal surgical treatment for their abdominal aortic aneurysms were included in the study. The initial diagnosis of the aortic dilatation was made by ultrasonography and, after the surgical treatment was indicated, the patient was submitted to another imaging method.Sixty patients were divided into 3 groups according to the complementary imaging method (conventional computerised tomography, helical computerized tomography, nuclear ...
1990-01-01
The labelling of red blood cells (RBC) and plasma proteins (PP) with Technetium-99 m (99mTc), as pertechnetate, depends on the presence of a reducing agent and the stannous ion is usually used. Gentamicin, verapamil and nifedipine are calcium (Ca++) channel blockers. Due to similarities between Ca++ and Sn++, these drugs have been used for evaluating the mechanisms for labelling RBC and PP with 99mTc. Blood with anticoagulant have been treated with these drugs for 15 min and have been incubated with stannous ions solution for different times. Then, 99mTc put into vials. The percentages of labelling were then calculated. The results show that, under certain conditions, gentamicin, verapamil and nifedipine are capable to alter the 99mTc incorporation. We suggest that stannous ion ...
Atmospheric X-rays at 11/sup 0/S geomagnetic latitude
1986-05-01
X-ray measurements at balloon altitudes were made at Sao Jose dos Campos, Brasil (23/sup 0/12'S,45/sup 0/51'W geographic coordinates, approx. 11/sup 0/S geomagnetic latitude) on 18 December 1981, using an omnidirectional NaI(Tl) scintillation detector. Atmospheric X-rays, namely secondary X-radiation from cosmic rays, were measured for the energy interval 30-155 keV and up to an atmospheric depth of 5.5 g cm/sup -2/. A comparison of the flux measured at the Pfotzer maximum during these measurements with those obtained previously by several research groups at other latitudes and with a similar technique has also been made. A comparison of the atmospheric component with that attributed to the diffuse component is also presented and it is concluded that both components are of about the same magnitude at approx. 5 g cm/sup -2/ and at approx. 11/sup 0/S geomagnetic latitude.
Atmospheric X-rays at 11 deg S geomagnetic latitude
1985-05-01
X-ray measurements at balloon altitudes were performed at Sao Jose dos Campos, Brazil (23 deg 12 min. S, 45 deg 51 min. W geographic coordinates, -11 deg S geomagnetic latitude) on December 18, 1981, using an omnidirectional NaI(Tl) scintillation detector. Atmospheric X-rays, namely, secondary X-radiation from cosmic rays, were measured for the energy interval of 30 to 155 MeV and up to an atmospheric depth of 5.5 g/sq cm. A comparison of the flux measured at the Pfotzer maximum during these measurements with those obtained in the post by several research groups, at other latitudes and with similar technique, is also shown. Finally, a comparison of the atmospheric component with that attributed to the diffuse component is also presented and it is concluded that both components are of about the same magnitude at L approximately 5 g/sq cm and at approximately 11 deg S geomagnetic latitude.
2005-01-01
123I is a gamma emitter used for diagnosis in Nuclear Medicine. Since 1998 it is produced in the Institute of Nuclear Energy (IEN) and supplied to the Clinics and Hospitals located in the city of Rio de Janeiro. The annual production is in the approximately of 0,74 TBq (20 Ci), which represents a risk of external and internal exposure to the workers involved in this activity. A survey of external doses in the period of 1994 to 2004 was carried out based on the individual registries available in the CONEXO Data Base operated by the Institute of Radiation Protection and Dosimetry (IRD). It was verified an increase of the external exposure associated to the production curve. However, the individual doses are all bellow the annual limits established by the regulatory board. On the other hand, the variation of doses among individuals involved in the same tasks suggests the ...
2007-01-01
This study aimed to evaluate the effect of inhibition of the inflammatory chains governed by the action of interferon-gamma (IFN-gamma) and the enzyme inducible nitric oxide synthase (iNOS) in damage after radiation exposure to lethal dose (8 Gy) or moderate /severe dose (4 Gy) in hematopoietic tissues (spleen and bone marrow) of experimental models irradiated at these doses. Groups of isogenic C57Bl/6J mice were exposed to radiation (4 or 8 Gy) in whole-body exposures in a 60Co panoramic source. Similarly, were irradiated mice whose iNOS or IFN-gamma expression was absent or undetectable. Other groups received orally in all days of experiments an inhibitor of iNOS activity, aminoguanidine, or CXCL12, a primordial chemokine known as an haematopoiesis promoter intraperitoneally by days 0 to fourth after radiation events. Another ...
1995-01-01
Spectrophotometric methods for uranium (IV), hydrazine (N2H4) and its decomposition product hydrazoic acid(HN3), and hydroxylamine (NH2 OH) determinations were developed aiming their applications for the process control of CELESTE I installation at IPEN/CNEN-SP. These compounds are normally present in the U/Pu partitioning phase of the spent nuclear treatment via PUREX process. The direct spectrophotometry was used for uranium (IV) analysis in nitric acid-hydrazine solutions based on the absorption measurement at 648 nm. The azomethine compound formed by reaction of hydrazine and p-dimethylamine benzaldehyde with maximum absorption at 457 nm was the basis for the specific analytical method for hydrazine determination. The hydrazoic acid analysis was performed indirectly by its conversion into ferric azide ...
2005-01-01
The major technique to detect genetically modified organism - GMO is the polymerase chain reaction - PCR. The PCR is a method that allows the enlargement in vitro of DNA segments, using two starters ('primers') that hybridize with the opposing ribbons, in regions that match the segment to be amplified. For that, the DNA is disnatured (92-96 deg C), the 'primers' are hybridized (30 deg C a 60 deg C ) and, after that, the DNA synthesis is made with a DNA-polymerase and nucleotides (dNTPs) (72 deg C), for some repetitive cycles. The development of the PCR allowed great advances in Molecular Biology, mainly for analysis of genes, diagnosis of illnesses and pathogens, among some other examples. Currently, the PCR has been very much used for the identification of transgenic constituents in foods. In the detection of genetically modified grains, the PCR technique showed to be highly ...
In order to study density of states (DOS) effects on the resistivity of liquid metals and alloys we derive a set of integral equations for these quantities so that this set satisfies the generalized optical theorem. The DOS is calculated up to second orde...
Variabilidade ptica de longo perodo e precesso de jato: o caso de BL Lacertae
Variabilidade tipicamente uma caracterstica de AGNs, sendo observada em toda a faixa eletromagntica. Em relao s escalas de tempo, variaes desde horas at de algumas dcadas foram encontradas por vrios autores. Em alguns casos, anlises temporais de curvas de luz mostram a existncia de periodicidade nas variaes observadas. Um exemplo de objeto que preenche as caractersticas mencionadas acima BL Lacertae, o prottipo da classe BL Lac dos AGNs. Neste trabalho, ns interpretamos a variabilidade peridica de longo perodo detectada na curva de luz na banda B (~7,5 anos) como o resultado da periodicidade na amplificao da radiao oriunda do jato relativstico. Neste cenrio, a amplificao peridica seria induzida pela precesso, que muda o ngulo entre o jato e a linha de visada. Com esta abordagem e vnculos adicionais fornecidos por observaes em altas energias, ns podemos impor limites para os parmetros do modelo de precesso, tais como o fator de Lorentz associado ao movimento global do jato, o ngulo de abertura do cone de precesso e o ngulo entre o eixo do cone e a linha de visada.
Textos acadêmicos, no formato de zip documentos, na área de etnomatemática tais como resumos de dissertações e de teses, de trabalhos apresentados em congressos e artigos de pesquisadores com produções mais recentes e/ou relevantes: O uso da matemática na agricultura: o caso dos produtores de cana-de-açúcar; A lógica do jogo do bicho: compreensão ou utilizaão de regras? Um estudo de etnomatemática: sua incorporação na elaboração de uma proposta pedagógica para o Núcleo Escola da Favela da Vila Nogueira/São Quirino; Dimensões sociais, políticas e culturais da educação matemtica: os seus reflexos nos cursos de licenciatura; Space notion and children in the street situation; e outros.
2008-01-01
A bridge modified 4-tert-butylthiacalix[4]arene (I) has been employed as electroactive material in the preparation of cobalt selective sensor. Polyvinyl chloride (PVC)-based membranes of (I) using sodium tetraphenylborate (NaTPB) as anion discriminator and bis(2-ethylhexyl) sebacate (DOS), chloronaphthalene (CN), tri-n-butylphosphate (TBP), o-nitrophenyl octyl ether (NPOE), tris(2-ethylhexyl)phosphate (TEHP) as plasticizers were prepared and investigated as cobalt selective sensors. A number of membranes of different compositions were prepared and investigated. The best performance was observed with the membrane having composition of 2:66:1.5:127 (mg) = I:NaTPB:PVC:NPOE. The potential response of this membrane is linear to Co2+ ions in the concentration range 5.3 × 10-6 to 1.0 × 10-1 M with near-Nernstian slope of 30.0 mV/decade of activity and a detection limit of 0.3 ppm. This membrane also showed lowest response time of 10 s and works satisfactorily in partially non-aqueous medium. The selectivity studies of this sensor, evaluated with fixed interference method and matched potential method, show that the sensor under consideration possesses excellent selectivity for Co2+ over a large number of mono-, bi- and trivalent cations such as Na+, K+, Ag+, Ca2+, Mg2+, Cu2+, Hg2+, Pb2+, Li+, Ba2+, Zn2+, Sr2+, Cr3+, Ni2+, etc. The sensor could be used as an indicator electrode in the quantification of Co2+ by potentiometric titration against EDTA as well as in determination of cobalt content in wastewater and beer samples. Coverage: 2008-01-01T00:00:00Z
Ecoturismo e Culturas Tradicionais Estudo de Caso: Martim de Sa
Enquanto alguns paises tem o ecoturismo como a sua principal fonte de renda, o Brasil nao explora a atividade de forma planejada, o que resulta, muitas vezes, na degradacao do meio ambiente e na descaracterizacao da diversidade cultural local. Assim sendo, este estudo pretende contribuir para a compreensao do processo de adaptacao de uma comunidade tradicional ao fenomeno do ecoturismo e dar um alerta para a necessidade de considerar a identidade cultural das populacoes locais como bem patrimonial e como elemento de risco no planejamento da atividade. Com esse intuito, foi realizado um Estudo de Caso, durante os anos de 2000 e 2001, com uma familia residente na praia de Martim de Sa, caracterizada como caicara. Essa comunidade foi escolhida, pois reside em um local onde o ecoturismo esta apenas comecando, fato que permitiu refletir a respeito das consequencias da atividade. Martim de Sa, apesar de estar inserida nos limites de duas Unidades de Conservacao da Natureza, esta sobre forte ameaca de degradacao ambiental devido a especulacao imobiliaria incentivada pelo crescimento do fluxo turistico sem planejamento e facilitado pela falta de fiscalizacao dos orgaos ambientais responsaveis por essas areas. Para o desenvolvimento do Estudo de Caso foram utilizadas nesta pesquisa a Observacao Participante e as entrevistas estruturadas com a finalidade de caracterizar a comunidade local e os turistas e, a Historia de Vida, para a reconstituicao da historia do nucleo receptor.
Contagem de fontes de radio na direo de aglomerados ricos de galaxias
A contagem de fontes de rdio, na direo de aglomerados ricos de galxias, deve fornecer uma distributo acima da mdia do campo devido aos efeitos do meio. No entanto, a distribuo de radiofontes de alguns aglomerados, investigada por vrios autores no passado, mostrou, em alguns casos, uma deficncia de fontes fracas. Neste trabalho, analisamos os levantamentos em 2.7 GHz (Reuter e Andernach 1990, 1990A&AS...82..279R; Loiseau et al. 1988, 1988A&AS...75...67L) e o catlogo 6CII em 151 MHz (Hales et al. 1988, 1988MNRAS.234..919H). Nosso estudio da distribuo de radiofontes, na direo de aglomerados ricos de galxias, nestas duas frequncias, mostra um excesso de fontes fortes somente nas regies centrais dos aglomerados. Este resultado pode ser explicado devido evidncia de confinamento das radiofontes pelo gs, do meio intra-aglomerado, e devido aos processos de coliso, coalescncia e canibalismo de galxias.
Vibrational Properties of Nanograins and Interfaces in Nanocrystalline Materials
2008-01-01
The vibrational dynamics of nanocrystalline Fe90Zr7B3 was studied at various phases of crystallization. The density of phonon states (DOS) of the nanograins was separated from that of the interfaces for a wide range of grain sizes and interface thicknesses. The DOS of the nanograins does not vary with their size and down to 2 nm grains still closely resembles that of the bulk. The anomalous enhancement of the phonon states at low and high energies originates from the DOS of the interfaces and scales linearly to their atomic fraction
2010-04-01
As part of our ongoing efforts to uncover the phenotypic consequences of genetic variability among clinical Mycobacterium tuberculosis isolates, we previously reported that isolates...Full Text Available
Transferncias orbitais dentro do modelo quase bicircular no sistema Terra-Lua-Sol
O problema quase bicircular planar consiste na determinao da dinmica de um corpo, de massa desprezvel, que se move sob o campo gravitacional de trs corpos. No caso estudado, o quarto corpo considerado um satlite artificial e os demais so a Terra, a Lua e o Sol, formando o sistema de trs corpos. Este modelo permite a construo de uma hamiltoniana similar a do problema restrito de trs corpos (PRTC), incluindo termos peridicos no autnomos, provenientes da presena do Sol, portanto pode ser entendido como uma perturbao ao PRTC. Suas rbitas peridicas aparecem isoladas e possuem o mesmo perodo solar. Os pontos de equilbrio colineares possuem o mesmo carter de estabilidade linear dos pontos lagrangianos (L1, L2 e L3) do PRTC, sendo do tipo sela x centro x centro, instvel na direo x e estveis nas direes y e z. As rbitas peridicas tridimensionais ao redor do ponto colinear chamada rbita Halo. O objetivo deste trabalho determinar rbitas de transferncias de baixo consumo de combustvel para um veculo espacial partindo de uma rbita de estacionamento ao redor da Terra em direo a uma rbita Halo do ponto L1, situado entre a Terra e Lua. Esta tarefa pode ser transformada no problema de valor de contorno: dado um ponto inicial na rbita de estacionamento, um ponto final na rbita halo e o tempo de transferncia, deseja-se obter a trajetria que liga estes dois pontos e que minimize os incrementos de velocidade do veculo. Essas transferncias so realizadas baseadas no mtodo de Lambert e analisadas de modo a fornecer um baixo consumo. Posteriormente, feita uma comparao de consumo com as rbitas de transferncia equivalentes do PRTC.
O efeito do achatamento nos pontos de equilbrio e na dinmica de sistemas coorbitais
Neste trabalho analisamos o efeito do achatamento do corpo principal nos pontos de equilbrio lagrangianos e na configurao de rbitas girino-ferradura. Enfatizamos os sistemas coorbitais de satlites de Saturno, pois se encontram em relativa proximidade com o planeta, em que o efeito do achatamento se torna mais evidente. O estudo dividido em trs etapas independentes. Na primeira fase analisamos as equaes de movimento do problema restrito de trs corpos considerando o efeito do achatamento, e atravs do balanceamento de foras buscamos a nova configurao dos pontos de equilbrio lagrangianos. Conclumos, nesta etapa, que os pontos de equilbrio estveis apresentam um pequeno deslocamento definido pelo parmetro de achatamento, no podendo ser mais representados por tringulos eqilteros. Aplicamos este resultado aos satlites coorbitais de Tetis e Dione, encontrando as posies de equilbrio levemente deslocadas em relao ao caso sem achatamento. Na segunda fase visamos o sistema Saturno-Jano-Epimeteu, que por se tratar de um sistema de massas comparveis, optamos por desenvolver as equaes de Yoder et al (Icarus 53, pg 431-443, 1983), que permitem determinar os pontos de equilbrio e a amplitude de oscilao angular das rbitas girino-ferradura para o problema no-restrito de trs corpos, porm, no nosso estudo consideramos o efeito do achatamento do corpo principal nestas equaes. Encontramos que a distncia angular entre satlites, quando em posio de equilbrio estvel, diminui quanto maior for o parmetro de achatamento do corpo principal. Alm disso, a rbita de transio girino-ferradura possui largura angular menor em relao ao caso sem achatamento. Por fim, realizamos integraes numricas para os casos reais de coorbitais de Saturno comparando com os resultados analticos. Nestas integraes simulamos diversas rbitas girino-ferradura com diferentes parmetros de achatamento, utilizando condies iniciais corrigidas para a presena do achatamento.
1998-07-01
Prior incubation of the E. coli cultures with the iron ions chelator 2,2'-dipyridyl (1 mM) caused an intensification of the lethality and the mutagenesis induced by the hydrogen peroxide, mainly at high concentrations (20 mM). It was also detected an enhancement of DNA strand breaks in this condition. The addition of the copper ions chelator neocuproine blocked partially this phenomenon. The enzymes XthA and Nfo act alternatively in the repair of the lesions induced by H{sub 2}O{sub 2} in the presence of 2,2'-dipyridyl. H{sub 2}O{sub 2} can act synergistically with neocuproine in killing E. coli, causing an enhancement in DNA strand breaks. The recombinational repair, the UvrABC excinuclease and Fpg function appeared to participate in the repair of the synergistic lesions. (author)
Descoberta de um aglomerado estelar massivo associado a fonte IRAS 16177-5018
Neste trabalho apresentamos a descoberta de um aglomerado de estrelas jovens e massivas embebido em uma regio HII extensa associado com a fonte IRAS 16177-5018, que se apresenta invisvel na faixa ptica do espectro eletromagntico, onde a extino da ordem de AV = 26 magnitudes. As observaes foram feitas com a camera infravermelha (CamIV) do Laboratrio Nacional de Astrofsica, Brasil, equipada com um detector Hawaii de HgCdTe de 10241024 pixel acoplada ao telescpio de 60 cm Boller & Chivens do IAG. A fotometria obtida a partir das imagens nas bandas J, H e K (filtro estreito) mostrou a presena de fontes com excesso de emisso no infravermelho em 2.2 mm, concentradas em uma rea de aproximadamente um minuto de arco quadrado em torno da nebulosa na qual esta embebido o objeto identificado como a fonte IRAS. A fonte IRAS apresenta um ndice espectral (entre 2.2 21.3 mm) a = d log(l Fl) / d log l = 4.78, caracterstico de um objeto extremamente jovem com luminosidade bolomtrica (obtida da integral da densidade de fluxo entre o infravermelho prximo (1.25mm) e o infravermelho distante (100mm)) de 2.8105L, o qual corresponde a uma estrela da sequncia principal de idade zero de cerca de 42 M. A partir do diagrama cor-magnitude foi possvel classificar a maioria dos membros do aglomerado como estrelas massivas mais luminosas que tipo espectral B5.
Corpos no interior de um recipiente fechado e transparente em queda livre
2008-09-10
Neste artigo discutimos uma nova demonstracao experimental da independencia das propriedades dos corpos (massa, composicao quimica, forma, etc.) na queda livre. Eh uma das experiencias mais simples, porem uma das mais importantes da Mecanica, tendo sido realizada e repensada repetidamente por diversos cientistas tais como Galileu e Newton. Nossa versao eh introduzir dentro de uma garrafa fechada e transparente uma pena e uma pedra observando a queda simultanea destes corpos. Por nao haver a necessidade de produzir vacuo, esta versao pode ser repetida por qualquer aluno e professor de ensino medio e universitario em qualquer ambiente, evidenciando sua viabilidade e aplicabilidade na sala de aula. English version of abstract: In this paper we discuss a new experimental demonstration of the independence of the properties of bodies (mass, chemical composition, shape, etc) in free fall. This is one of the simplest experiments in mechanics, though one of the most important ones, having been repeatedly carried out and rethought by several scientists such as Galileo and Newton. Our version of this famous experiment uses one bottle (closed and transparent), in which we introduce a feather and a stone, observing the simultaneous free fall of these bodies. Because it is not necessary to create vacuum, this version can be repeated by teachers and students alike either in secondary schools or universities in any environment. Thus its viabil ity and applicability in the classroom is evident.
2008-07-01
The pollution for oil has been one of the main ambient problems of the last decades. It exists an increasing interest in the study of the destination and forms of disappearance of the constituent hydrocarbons of the oil aiming at the development of more efficient methods of removal of the same ones of the environment. With objective to evaluate the process photo-fenton, in the treatment of the contaminated saline superficial water with polyaromatics hydrocarbons (HPAs) contained in the crude oil, mounted an experiment using reactor of black light, the hydrogen peroxide as oxidant agent. After the degradation the samples had been submitted to the analysis in the GC-MS, and for the 31 specters it was observed that the best ones resulted had been gotten when mmol of H{sub 2}O{sub 2} in 8 was used h of exposition to the irradiation and with pH of the equal system the 4. In the specter of this assay the characteristic peaks of the HPAs disappear completely or appear in a lowly intensities, proving that it had rupture of aromatical rings consequently and the degradation of the same ones or that its concentrations meet below of the limit of detention of the equipment. Soon, with the gotten results it can be concluded that the POAs, in special the process photo-fenton, is presented as a viable alternative in the contaminated saline superficial water treatment with the HPAs contained in the rude oil. (author)
2006-07-01
The paper focuses the 'alcohol crisis' at the earliest 2006, analysing the movement of the prices rising and hydrated alcohol and the common gasoline sales at the light of technological flexibility introduced by the flex fuel vehicles. By temporal series tests the article; points out the nonstationary of the alcohol prices movement related to the gasoline; arguments that this relationship should be analyzed under a long term optics; and also point out that, given the present technological flexibility which rises up the substitution character existent among the fuels, reactions over eventual short time movements of the prices should not justify punctual interventions of the Government. The concludes that there is not rupture on supply of the referred fuel; and the recent 'crisis' was generated by total absence of inter temporal strategic perception by the involved agents.
Esta adoptando Asia la flexiseguridad?
2010-01-01
Resumen. Incitados por la competencia mundial, muchos paises estan adaptando la reglamentacion laboral al principio de la flexiseguridad, que da a las empresas mas flexibilidad para contratar y despedir a los trabajadores, al tiempo que ampara a estos cuando deben pasar de un empleo a otro. El presente estudio de seis paises asiaticos indica que China y Republica de Corea han promulgado reformas de este genero; Singapur y Malasia han implantado algunos elementos de flexiseguridad, pero no un seguro de desempleo, y la India y Sri Lanka han hecho pocas reformas y mantienen un modelo anticuado en el que la proteccion depende de la empresa. Para prestar apoyo a los trabajadores del sector informal, China, India y Sri Lanka se valen de obras publicas y de programas de fomento del trabajo por cu...
Precesso do jato de 3C120: simulaes hidrodinmicas 3D
Observaes com tcnicas de interferometria com longa linha de base tm mostrado a existncia de um jato relativstico com componentes superluminais na regio central de 3C 120. Estas componentes so ejetadas em distintas direes no plano do cu e com diferentes velocidades aparentes. Estas caractersticas foram interpretadas em trabalhos anteriores como efeitos da precesso do jato relativstico. Neste trabalho, realizamos simulaes tri-dimensionais do jato de 3C 120 utilizando os parmetros de precesso determinados em trabalhos anteriores e variando as caractersticas iniciais do jato e meio ambiente, tais como densidade numrica e temperatura. Todas as simulaes foram feitas com o cdigo hidrodinmico YGUAZ-A, assumindo-se um jato adiabtico descrito por uma equao de estado relativstica. Pelo fato de estarmos utilizando um cdigo hidrodinmico, ns assumimos que a intensidade do campo magntico e a distribuio de partculas, necessrios para se calcular a emisso sincrotron, so proporcionais presso hidrodinmica. Comparao entre dois cenrios distintos, nos quais o material do jato ejetado com velocidade constante (jato contnuo) e com velocidade modulada por um padro sinusoidal no tempo (jato intermitente), apresentada e discutida. Para jatos que apresentam fenmenos de precesso e intermitncia, com amplitude de variao na velocidade de injeo maior que dez por cento da velocidade mdia de injeo, a hiptese balstica, controlada pela intermitencia, mais provvel. Por outro lado, para jatos com precesso mas sem intermitncia (ou com amplitude de variabilidade em velocidade mais baixa que no caso anterior), o efeito da precesso na morfologia do jato no desprezvel. Portanto, de um modo geral, ambos efeitos (precesso e movimentos balsticos) devem estar concorrendo para afetar a morfologia dos jatos superluminais.
Detecting Security threats in the Router using Computational Intelligence
2010-05-07
nformation security is an issue of global concern. As the Internet is delivering great convenience and benefits to the modern society, the rapidly increasing connectivity and accessibility to the Internet is also posing a serious threat to security and privacy, to individuals, organizations, and nations alike. Finding effective ways to detect, prevent, and respond to intrusions and hacker attacks of networked computers and information systems. This paper presents a knowledge discovery frame work to detect DoS attacks at the boundary controllers (routers). The idea is to use machine learning approach to discover network features that can depict the state of the network connection. Using important network data (DoS relevant features), we have developed kernel machine based and soft computing detection mechanisms that achieve high detection accuracies. We also present our work of identifying DoS pertinent features and evaluating the applicability of these features in detecting novel DoS attacks. Architecture for detecting DoS attacks at the router is presented. We demonstrate that highly efficient and accurate signature based classifiers can be constructed by using important network features and machine learning techniques to detect DoS attacks at the boundary controllers.
Nefropatia induzida por meio de contraste: Uma realidade para quem se submete a exames invasivos
2005-01-01
A nefropatia induzida por contraste é uma doença que vem, na atualidade, aumentando sua incidência, tal fato pode ser atribuído à realização cada vez mais freqüente de procedimentos diagnósticos e terapêuticos que empregam contraste radiológico e ao perfil clínico mais complexo dos pacientes que se submetem a tais exames. A nefropatia por contraste é a terceira causa de insuficiência renal aguda em pacientes hospitalizados1, rara em pacientes sem lesão renal prévia, aumentando sua freqüência com a progressiva redução da função renal2. Caracteriza-se pela diminuição aguda da função renal após o uso de contraste·endovenoso, em um período de 24 a 48 horas, com pico entre três e cinco dias e retorno·ao valor basal entre sete e dez dias. Os principais fatores de risco para o desenvolvimento de nefropatia por contraste são: disfunção renal prévia, diabetes melito, desidratação, insuficiência cardíaca congestiva e uso concomitante de drogas nefrotóxicas. Algum grau de disfunção renal prévia tem sido relatado em até 30% dos casos de nefropatia por contraste1. Além disso, o risco aumenta quando uma segunda dose de contraste é administrada em período curto de tempo (72 horas) da primeira exposição, fato de importância clinica, já que não é infreqüente que pacientes sejam submetidos a procedimentos diagnósticos e a seguir tratados na mesma internação, o que eleva o risco de lesão renal em até 40%. Publisher: Sociedade Brasileira de Cardiologia Coverage: 2005-10-01T00:00:00Z
2007-01-01
Austenitic stainless steel (AISI 304L), which was thermomechanically processed by introducing cold deformation followed by annealing, was sensitized. The percentage of coincident site lattice boundaries did not correlate well with the degree of sensitization (DOS). The material with grain sizes below 10mm was found to be the least sensitized, while specimens with larger grains showed an increase in DOS with sensitization time. The DOS is shown to have an inverse correlation with the grain boundary area, decreasing exponentially with increasing grain boundary surface area.
The LASL Respirator Research and Development Section, Industrial Hygiene Group, performed studies and conducted training for the Division of Operational Safety (DOS) during the second half of FY 1973. The major work involved development and initiation of a training course for AEC contractors and AEC personnel; writing a Respirator Manual for use by the AEC and their contractors; providing consulting services for the DOS and contractors; man testing several respirators; and holding a three-day Respirator Symposium jointly sponsored by the DOS, the Directorate of Regulatory Standards, and LASL. (auth)
Quantum statistical effects in nano-oscillator arrays
2005-04-22
We have theoretically predicted the density of states(DOS), the low temperature specific heat, and Brillouin scattering spectra of a large, free standing array of coupled nano-oscillators. We have found significant gaps in the DOS of 2D elastic systems, and predict the average DOS to be nearly independent of frequency over a broad band f 1.e14, and therefore such observations would extend the domain in which quantum mechanics has been experimentally tested. We have found the required measurement capability to carry out this investigation to be within reach of current technology.
The intraplate Porto dos Gachos seismic zone in the Amazon craton Brazil
2009-01-01
The largest earthquake observed in the stable continental interior of the South American plate occurred in Serra do Tombador, Mato Grosso state Brazil, on January 31, 1955 with a magnitude of 6.2 mb. Since then no other earthquake has been located near the 1955 epicentre. However, in Porto dos Gachos, 100km northeast of Serra do Tombador, a recurrent seismicity has been observed since 1959. Both Serra do Tombador and Porto dos Gachos are located in the Phanerozoic Parecis basin. Two magnitude 5 earthquakes occurred in Porto dos Gachos, in 1998 and 2005, with intensities up to VI and V, respectively. These two main shocks were followed by aftershock sequences lasting more than three years each. Local seismic stations have been deployed by the Seismological Observatory of the Uni...
1987-12-31
This work considers only the technical aspects of the specifications. However, it contributes to improve the specifications of the turbogenerators, indicating observations, comments and suggestions 1 tab.
Security Scheme for Distributed DoS in Mobile Ad Hoc Networks
2010-05-04
In Mobile Ad Hoc Networks (MANET), various types of Denial of Service Attacks (DoS) are possible because of the inherent limitations of its routing protocols. Considering the Ad Hoc On Demand Vector (AODV) routing protocol as the base protocol it is possible to find a suitable solution to over-come the attack of initiating / forwarding fake Route Requests (RREQs) that lead to hogging of network resources and hence denial of service to genuine nodes. In this paper, a proactive scheme is proposed that could prevent a specific kind of DoS attack and identify the misbehaving node. Since the proposed scheme is distributed in nature it has the capability to prevent Distributed DoS (DDoS) as well. The performance of the proposed algorithm in a series of simulations reveal that the proposed scheme provides a better solution than existing approaches with no extra overhead.
1978-01-01
By the fact of being the first Nuclear Plant to be built in Brasil , the Angra dos Reis Nuclear Plant has arisen a great interest to the national engineering.As this plant is the first of a great complex which is begining in the country, the divulgation of the technical problems found during the construction fase is a very valuable subsidy for the next plants. A summary of the concrete researches for the Angra dos Reis Nuclear Power Plants performed are presented, with emphasis on the high density concrete studies, and for the crack control through the temperature control. Strain capacity tests results with a slow loading equipment and creep tests combined with modulus of rupture are used to predict the crack resistence of concrete. (Author)
Electronic personal neutron dosemeters for energies up to 100 MeV: Calculations using the PHITS code
2008-01-01
Measurements and calculations of pulse height spectra induced by normally incident neutrons with energies between 144 keV and 100 MeV in silicon have been performed with the PTB prototype personal neutron dosemeters DOS-2002 and DOS-2005, based on silicon detectors with effective thicknesses of 40 and 5.6mum, respectively. This work describes calculations using the PHITS code and compares measured and calculated pulse height spectra and personal dose equivalent responses. Measurements and calculations agree on an absolute scale by a factor better than 2. The personal dose equivalent response of the prototype personal neutron dosemeter DOS-2005 is much flatter than that of the DOS-2002 in the neutron energy range investigated
2010-01-01
An analysis is presented of the layer-thickness dependent and temperature-dependent current density in sandwich-type electron-only devices based on the amorphous small-molecule organic semiconductor BAlq, which is frequently used in organic light-emitting diodes. The electron transport can be consistently described by assuming a density of states (DOS) which is a superposition of a Gaussian DOS and an exponential trap DOS, with 85 and 100meV widths, respectively, using a mobility model which includes the carrier density dependence of the mobility in the Gaussian DOS and assuming either random or spatially correlated site energies. From a comparison of the density of hopping sites obtained from both models and the density of molecules as obtained from chemical analysis, evidence for the pre...
An Experimental Study of the Performance Impact of Path-Based DoS Attacks in Wireless Mesh Networks
2010-01-01
Wireless mesh networks (WMNs) are considered as cost effective, easily deployable and capable of extending Internet connectivity. However, one of the major challenges in deploying reliable WMNs is preventing their nodes from malicious attacks, which is of particular concern as attacks can severely degrade network performance. When a DoS attack is targeted over an entire communication path, it is called a path-based DoS attack. We study the performance impact of path-based DoS attacks by considering attack intensity, medium errors, physical diversity, collusion and hop count. We setup a wireless mesh testbed and configure a set of experiments to gather realistic measurements, and assess the effects of different factors. We find that medium errors have significant impact on the performance o...
Modelo de atmosfera solar ajustado s observaes do raio solar em 17GHz
O estudo das variaes do raio solar durante o ciclo de atividades do Sol e das diferenas em relao sua distribuio angular nos fornece informaes importantes sobre as mudanas na estrutura da atmosfera solar. Neste trabalho foram analisados mais de 3600 mapas do Sol em 17 GHz obtidos pelo Rdio Heligrafo de Nobeyama (NoRH), durante 1 ciclo de atividade solar (1992-2003). O raio solar foi definido no ponto onde a temperatura de brilho do mapa era equivalente metade da temperatura do Sol calmo (temperatura mais comum no mapa).Em relao sua variao ao longo do ciclo solar, o estudo foi dividido em duas partes: a) ajuste de uma circunferncia a pontos distribudos ao redor do Sol todo. Este estudo mostrou uma variao correlacionada com o ciclo de atividade do Sol. b) ajuste da circunferncia a pontos situados somente nas regies polares. Neste caso os resultados mostraram que o raio polar sofre pouca variao durante o ciclo, com tendncia anticorrelao com este. Alm disto, a mdia do raio polar, durante o perodo analisado, foi 1" menor que o raio medido no Sol todo. Para estudar a distribuio angular do raio solar, comparamos a mdia da distribuio de 10 mapas no perodo de mnima atividade solar com a mdia de 10 mapas no perodo de mximo, este estudo mostrou um grande aumento do raio na regio equatorial no perodo de mxima atividade solar. As medidas do raio foram usadas como um dos parmetros para a criao de um modelo atmosfrico (alm da temperatura de brilho do Sol e do abrilhantamento do limbo observado), onde mostramos que um modelo atmosfrico com a regio de transio situada a 3500 km fornece um raio 5" menor que as medidas observacionais. Esta incompatibilidade do modelo com os dados observacionais foi contornada com a incluso de espculas, estas fazem com que o raio solar aumente proporcionalmente altura que estas atingem na atmosfera solar. A anticorrelao do raio polar com ciclo de atividade pode ser interpretada como reflexo do aumento de abrilhantamento de limbo nos plos, visto que este est anticorrelacionado com o ciclo solar. Porm, a presena de espculas, no capaz de explicar os valores muito altos do raio solar medidos na regio equatorial, que acreditamos ser devido s mudanas intrnsecas na estrutura local da atmosfera solar.
INTEGRATED HYDROGEN STORAGE SYSTEM MODEL
Hydrogen storage is recognized as a key technical hurdle that must be overcome for the realization of hydrogen powered vehicles. Metal hydrides and their doped variants have shown great promise as a storage material and significant advances have been made with this technology. In any practical storage system the rate of H2 uptake will be governed by all processes that affect the rate of mass transport through the bed and into the particles. These coupled processes include heat and mass transfer as well as chemical kinetics and equilibrium. However, with few exceptions, studies of metal hydrides have focused primarily on fundamental properties associated with hydrogen storage capacity and kinetics. A full understanding of the complex interplay of physical processes that occur during the charging and discharging of a practical storage system requires models that integrate the salient phenomena. For example, in the case of sodium alanate, the size of NaAlH4 crystals is on the order of 300nm and the size of polycrystalline particles may be approximately 10 times larger ({approx}3,000nm). For the bed volume to be as small as possible, it is necessary to densely pack the hydride particles. Even so, in packed beds composed of NaAlH{sub 4} particles alone, it has been observed that the void fraction is still approximately 50-60%. Because of the large void fraction and particle to particle thermal contact resistance, the thermal conductivity of the hydride is very low, on the order of 0.2 W/m-{sup o}C, Gross, Majzoub, Thomas and Sandrock [2002]. The chemical reaction for hydrogen loading is exothermic. Based on the data in Gross [2003], on the order of 10{sup 8}J of heat of is released for the uptake of 5 kg of H{sub 2}2 and complete conversion of NaH to NaAlH{sub 4}. Since the hydride reaction transitions from hydrogen loading to discharge at elevated temperatures, it is essential to control the temperature of the bed. However, the low thermal conductivity of the hydride makes it difficult to remove the heat of reaction, especially in the relatively short target refueling times, see Attachment 3. This document describes a detailed numerical model for general metal hydride beds that couples reaction kinetics with heat and mass transfer, for both hydriding and dehydriding of the bed. The detailed model is part of a comprehensive methodology for the design, evaluation and modification of hydrogen storage systems. In Hardy [2007], scoping models for reaction kinetics, bed geometry and heat removal parameters are discussed. The scoping models are used to perform a quick assessment of storage systems and identify those which have the potential to meet DOE performance targets. The operational characteristics of successful candidate systems are then evaluated with the more detailed models discussed in this document. The detailed analysis for hydrogen storage systems is modeled in either 2 or 3-dimensions, via the general purpose finite element solver COMSOL Multiphysics{reg_sign}. The two-dimensional model serves to provide rapid evaluation of bed configurations and physical processes, while the three-dimensional model, which requires a much longer run time, is used to investigate detailed effects that do not readily lend themselves to two-dimensional representations. The model is general and can be adapted to any geometry or storage media. In this document, the model is applied to a modified cylindrical shell and tube geometry with radial fins perpendicular to the axis, see Figures 4.1-1 and 4.1-2. Sodium alanate, NaAlH{sub 4}, is used as the hydrogen storage medium. The model can be run on any DOS, LINUX or Unix based system.
INTEGRATED HYDROGEN STORAGE SYSTEM MODEL
Hydrogen storage is recognized as a key technical hurdle that must be overcome for the realization of hydrogen powered vehicles. Metal hydrides and their doped variants have shown great promise as a storage material and significant advances have been made with this technology. In any practical storage system the rate of H2 uptake will be governed by all processes that affect the rate of mass transport through the bed and into the particles. These coupled processes include heat and mass transfer as well as chemical kinetics and equilibrium. However, with few exceptions, studies of metal hydrides have focused primarily on fundamental properties associated with hydrogen storage capacity and kinetics. A full understanding of the complex interplay of physical processes that occur during the charging and discharging of a practical storage system requires models that integrate the salient phenomena. For example, in the case of sodium alanate, the size of NaAlH4 crystals is on the order of 300nm and the size of polycrystalline particles may be approximately 10 times larger ({approx}3,000nm). For the bed volume to be as small as possible, it is necessary to densely pack the hydride particles. Even so, in packed beds composed of NaAlH{sub 4} particles alone, it has been observed that the void fraction is still approximately 50-60%. Because of the large void fraction and particle to particle thermal contact resistance, the thermal conductivity of the hydride is very low, on the order of 0.2 W/m-{sup o}C, Gross, Majzoub, Thomas and Sandrock [2002]. The chemical reaction for hydrogen loading is exothermic. Based on the data in Gross [2003], on the order of 10{sup 8}J of heat of is released for the uptake of 5 kg of H{sub 2}2 and complete conversion of NaH to NaAlH{sub 4}. Since the hydride reaction transitions from hydrogen loading to discharge at elevated temperatures, it is essential to control the temperature of the bed. However, the low thermal conductivity of the hydride makes it difficult to remove the heat of reaction, especially in the relatively short target refueling times, see Attachment 3. This document describes a detailed numerical model for general metal hydride beds that couples reaction kinetics with heat and mass transfer, for both hydriding and dehydriding of the bed. The detailed model is part of a comprehensive methodology for the design, evaluation and modification of hydrogen storage systems. In Hardy [2007], scoping models for reaction kinetics, bed geometry and heat removal parameters are discussed. The scoping models are used to perform a quick assessment of storage systems and identify those which have the potential to meet DOE performance targets. The operational characteristics of successful candidate systems are then evaluated with the more detailed models discussed in this document. The detailed analysis for hydrogen storage systems is modeled in either 2 or 3-dimensions, via the general purpose finite element solver COMSOL Multiphysics{reg_sign}. The two-dimensional model serves to provide rapid evaluation of bed configurations and physical processes, while the three-dimensional model, which requires a much longer run time, is used to investigate detailed effects that do not readily lend themselves to two-dimensional representations. The model is general and can be adapted to any geometry or storage media. In this document, the model is applied to a modified cylindrical shell and tube geometry with radial fins perpendicular to the axis, see Figures 4.1-1 and 4.1-2. Sodium alanate, NaAlH{sub 4}, is used as the hydrogen storage medium. The model can be run on any DOS, LINUX or Unix based system.
INTEGRATED HYDROGEN STORAGE SYSTEM MODEL
2007-11-16
Hydrogen storage is recognized as a key technical hurdle that must be overcome for the realization of hydrogen powered vehicles. Metal hydrides and their doped variants have shown great promise as a storage material and significant advances have been made with this technology. In any practical storage system the rate of H2 uptake will be governed by all processes that affect the rate of mass transport through the bed and into the particles. These coupled processes include heat and mass transfer as well as chemical kinetics and equilibrium. However, with few exceptions, studies of metal hydrides have focused primarily on fundamental properties associated with hydrogen storage capacity and kinetics. A full understanding of the complex interplay of physical processes that occur during the charging and discharging of a practical storage system requires models that integrate the salient phenomena. For example, in the case of sodium alanate, the size of NaAlH4 crystals is on the order of 300nm and the size of polycrystalline particles may be approximately 10 times larger ({approx}3,000nm). For the bed volume to be as small as possible, it is necessary to densely pack the hydride particles. Even so, in packed beds composed of NaAlH{sub 4} particles alone, it has been observed that the void fraction is still approximately 50-60%. Because of the large void fraction and particle to particle thermal contact resistance, the thermal conductivity of the hydride is very low, on the order of 0.2 W/m-{sup o}C, Gross, Majzoub, Thomas and Sandrock [2002]. The chemical reaction for hydrogen loading is exothermic. Based on the data in Gross [2003], on the order of 10{sup 8}J of heat of is released for the uptake of 5 kg of H{sub 2}2 and complete conversion of NaH to NaAlH{sub 4}. Since the hydride reaction transitions from hydrogen loading to discharge at elevated temperatures, it is essential to control the temperature of the bed. However, the low thermal conductivity of the hydride makes it difficult to remove the heat of reaction, especially in the relatively short target refueling times, see Attachment 3. This document describes a detailed numerical model for general metal hydride beds that couples reaction kinetics with heat and mass transfer, for both hydriding and dehydriding of the bed. The detailed model is part of a comprehensive methodology for the design, evaluation and modification of hydrogen storage systems. In Hardy [2007], scoping models for reaction kinetics, bed geometry and heat removal parameters are discussed. The scoping models are used to perform a quick assessment of storage systems and identify those which have the potential to meet DOE performance targets. The operational characteristics of successful candidate systems are then evaluated with the more detailed models discussed in this document. The detailed analysis for hydrogen storage systems is modeled in either 2 or 3-dimensions, via the general purpose finite element solver COMSOL Multiphysics{reg_sign}. The two-dimensional model serves to provide rapid evaluation of bed configurations and physical processes, while the three-dimensional model, which requires a much longer run time, is used to investigate detailed effects that do not readily lend themselves to two-dimensional representations. The model is general and can be adapted to any geometry or storage media. In this document, the model is applied to a modified cylindrical shell and tube geometry with radial fins perpendicular to the axis, see Figures 4.1-1 and 4.1-2. Sodium alanate, NaAlH{sub 4}, is used as the hydrogen storage medium. The model can be run on any DOS, LINUX or Unix based system.
Observaes de Supernovas do tipo Ia mostram que a expanso do Universo est acelerando. Segundo as equaes de Einstein uma componente com presso negativa (energia escura) necessria para explicar a acelerao csmica. Alm da energia escura usualmente admitido que no Universo h tambm uma matria extica com presso zero, que chamada de matria escura. Essa componente possui um papel fundamental na formao de estruturas no Universo. Recentemente tem se explorado a possibilidade de que matria e energia escura poderiam ser unificadas atravs de uma nica componente, que tem sido denominada de quartessncia. Um exemplo de fluido com essas caractersticas o Gs de Chaplygin Generalizado, que possui uma equao de estado da forma p = -A/ra. Inicialmente consideramos o caso especial a = 1 (gs de Chaplygin) e vinculamos parmetros do modelo utilizando observaes em raios-X do satlite Chandra da frao de massa de gs em aglomerados de galxias. Uma comparao dos vnculos obtidos com esse teste com outros testes, tais como supernovas e idade do Universo, mostra que esse teste bastante restritivo. Exibiremos ainda resultados para o caso em que a curvatura nula e o parmetro a est compreendido no intervalo -1 < a 1.
Uma comparao entre tcnicas de propagao de erros em astrofsica: Monte Carlo x Bootstrap
Recentemente Dhillon & Watson (2001) criticaram o procedimento de determinao de erros via simulaes de Monte Carlo no caso do imageamento indireto de estrelas, por introduzir rudo nos dados e resultar em erros superestimados. Estes autores propuseram a utilizao alternativa do mtodo de Bootstrap como uma tcnica superior para a estimativa de erros. Neste trabalho apresentamos os resultados de um estudo comparativo da performance das tcnicas de simulao por Monte Carlo e por Bootstrap para a determinao de erros em duas situaes de interesse: (i) ajuste de modelos a espectros observados e (ii) imageamento indireto de discos de acrscimo com tcnicas de mapeamento por eclipse. No caso (i), os dados de entrada so espectros de emisso simples de hidrognio aos quais adicionado rudo gaussiano de amplitude selecionada. No caso (ii), so produzidas curvas de luz do eclipse de uma distribuio de brilho seguindo a lei TR-3/4 para discos estacionrios cuja taxa de acrscimo varia ao longo do eclipse segundo uma distribuio gaussiana de amplitude selecionada, simulando o rudo. A avaliao da performance feita com o auxlio de um diagrama do erro relativo na grandeza ajustada, conforme obtido por cada mtodo, versus o erro relativo (rudo/sinal) dos dados de entrada. O estudo mostra que as duas tcnicas produzem resultados semelhantes nos dois casos, e que a suposta superioridade do mtodo de Bootstrap no se confirma.
Trends in bulk electron-structural features of rocksalt early transition-metal carbides
A detailed and systematic density-functional theory (DFT) study of a series of early transition-metal carbides (TMCs) in the NaCl structure is presented. The focus is on the trends in the electronic structure and nature of bonding, which are essential for the understanding of the reactivity of TMCs. The employed approach is based on a thorough complementary analysis of the electron density differences, the density of states (DOS), the band structure and the real-space wavefunctions to gain an insight into the bonding of this class of materials and get a more detailed picture of it than previously achieved, as the trend study allows for a systematic identification of the bond character along the different bands. Our approach confirms the presence of both the well-known TM?C and TM?TM bonds and, more importantly, it shows the existence and significance of direct C?C bonds in all investigated TMCs, which are frequently neglected but have been identified in some cases (Zhang et al 2002 Solid State Commun. 121 411; Ruberto et al 2007 Phys. Rev. B 75 235438). New information on the spatial extent of the bonds, their k-space location within the band structure and their importance for the bulk cohesion is provided. Trends in covalency and ionicity are presented. The resulting electron-structural trends are analyzed and discussed within a two-level model.
2005-07-01
This paper presents the method used to helps the on land pipeline integrity management, focusing on external corrosion control. The method is achieved by gathering together the data from an Over The Line Survey (OLS) and an In Line Inspection (ILI). As the corrosion occurs at a coating fault in a non-effective cathodic protection (cp) area, both coating and metal loss inspection data were employed in this method. The OLS is applied to pinpoint and graduate the coating faults in underground pipeline by using the Coating Attenuation / A-Frame (ACVG - Alternate Current Voltage Gradient) technic. The ILI is applied to measure the external metal loss (corrosion) by running a smart PIG tool. In some pipelines a huge number of coating fault can be found, but it doesn't mean that all of them must be repaired, so it is a need to identify the critical coating fault, so that the number of digging for coating repair can be drastically reduced. In the other way, as the smart PIG can provide data of corrosion in the pipe, the coating fault on a corroded area can be considered as a critical one. Together, those data may point the spot where the cathodic protection was not effective and the coating failure resulted in corrosion on the pipe. This method has been a helpful criterion to identify critical coating faults and reduce the overall repair cost, it can be also used to indirect evaluate the performance of cp system, since no corrosion indication on a coating fault area can be assumed that the CP is effective. (author)
2004-07-01
Production strategies definition, applied to petroleum fields, must consider physical, operational and economic constraints. It is common to consider only the reservoir conditions on the optimization processes, simplifying, many times, the process by not taking into account the operational constraints due to production facilities. There are two main reasons: considering the operational constraints makes the process much complex and it is assumed that this simplification can affect the economic indicators but dos not affect significantly the optimization process (number e location of wells, for example). The capacity of a production unit can be limited by many constrains such as: maximum liquid rate, capacity of water and gas treatment, gas compression, water or gas injection, number of wells, etc. In this work, we show that these limitations have a direct influence in the oil production and consequently in the economic indicators and they can cause significant impact at production strategy definition, influencing the number of production and injection wells, their locations and their operational conditions. We presented an example of an offshore field with a limitation on the liquid rate. Production strategies were selected with and without constraints in order to observe the differences in the technical and economic indicators, such as NPV (Net Present Value), production and injection of fluids and the number and location of the production and injection wells. It was possible to observe yet that the amount and location of the wells were significantly affected by the restriction. (author)
2006-02-15
The main objective of radiotherapy is to deliver the highest possible dose to the tumour, in order to destroy it, reducing as much as possible the doses to healthy tissues adjacent to the target volume. Therefore, it is necessary to do a planning of the treatment. The more complex is the treatment, the more difficult the planning will be, demanding computation sophisticated methods in its execution, in order to consider the heterogeneities present in the human body. Additionally, with the appearing of new radiotherapeutic techniques, that used irradiation fields of small area, for instance, the intensity modulated radiotherapy, the difficulties for the execution of a reliable treatment planning, became still larger. In this work it was studied the influence of the lung heterogeneity in the planning of the curves of percentage depth dose, PDP, obtained with the Eclipse{sup R} planning system for different sizes of irradiation fields, using the correction algorithms for heterogeneities available in the planning system: modified Batho, general Batho and equivalent tissue-air ratio. A thorax phantom, manufactured in acrylic, containing a region made of cork to simulate the lung tissue, was used. The PDP curves generated by the planning system were compared to those obtained by Monte Carlo simulation and with the use of thermoluminescent, TL, dosimetry. It was verified that the algorithms used by the Eclipse{sup R} system for the correction of heterogeneity effects are not able to generate correct results for PDP curves in the case of small fields, occurring differences of up to 100%, when the 1x1 cm{sup 2} treatment field is considered. These differences can cause a considerable subdosage in the lung tissue, reducing the possibility of the patient cure. (author)
2003-07-01
The objective of this work is the study of the natural gamma radiation at the Areia Preta Beach (APB) in Guarapari, state of Espirito Santo, Brazil. The level of this radiation is dependent on the concentration of the radioactive mineral monazite in the sand. Probable risks of the exposure to gamma radiation at the APB were evaluated by the preliminary environmental risk analysis technique. For this purpose were conducted two annual sets monitoring gamma radiation in the APB every two months and so, acquired the seasonal variation of the radioactive levels. Additional/y was investigated the granulometry of the heavy mineral fraction and also carried out electronic microscopic scanning and radiometric age dating of the monazites of the APB, the mineral separation by magnetic susceptibility, and the mineralogic determination of the sediment. In order to gain a more complete picture of the seasonal variation, and, consequently, of the risk of exposure to ionizing radiation at the APB, the radiometric variation was also studied at some other beaches in the same region. The results indicate that the highest radiometric values are measured in summer and the lowest in winter. The radiometric dating of the monazites from the APB revealed the ages of 475 and 530 Ma. The Preliminary Hazard Analysis indicates a minimum risk of excessive radioactive exposition. It would take a period of approximately 870 years of a beach fully crowded to result in one case of bad consequences due to exposure to gamma radiation. (author)
2004-07-01
Several studies have shown the negative effects of surfactants, as detergents active substance, when discharged on biological sewage wastewater treatment plants. High toxicity may represent a lower efficiency for biological treatment. When surfactants are in aquatic environment they may induce a loss of grease revetment on birds (feather). Depending on the surfactant concentration, several damages to all biotic systems can happen. Looking for an alternative technology for wastewater treatment, efficient for surfactant removal, the present work applied ionizing radiation as an advanced oxidation process for affluents and effluents from Suzano Treatment Station. Such wastewater samples were submitted to radiation using an electron beam from a Dynamic Electron Beam Accelerator from Instituto de Pesquisas Energeticas e Nucleares. In order to assess this proposed treatment efficacy, it was performed acute toxicity evaluation with two test-organisms, the crustacean Daphnia similis and the luminescent bacteria Vibrio fischeri. The studied effluents were: one from a chemical industry (IND), three from sewage plant (affluents - GG, GM and Guaio) and the last biologically treated secondary effluent (EfF), discharged at Tiete river. The applied radiation doses varied from 3 kGy to 50 kGy, being 50 kGy enough for surfactant degradation contained at industrial effluent. For GG, GM and Guaio samples, doses of 6 kGy and 10 kGy were efficient for surfactant and toxicity reduction, representing an average removal that varied from 71.80% to 82.76% and toxicity from 30% to 91% for most the effluents. The final effluent was less toxic than the others and the radiation induced an average 11% removal for anionic surfactant. The industrial effluents were also submitted to an aeration process in order to quantify the contribution of surfactant to the whole sample toxicity, once it was partially removed as foam and several fractions were evaluated for toxicity. (author)
Resposta do detector de ondas gravitacionais Mario Schenberg ao "ringdown" de buraco negros
Acredita-se que quando duas estrelas de nutrons coalescem, elas, eventualmente, formam um buraco negro com massa igual a soma das massas dos objetos originais. Durante a formao do buraco negro, o espao-tempo em torno do sistema sofre perturbaes que se propagam na forma de radiao gravitacional. A forma de onda associada a radiao gravitacional, durante este estgio, aproxima-se a uma senide exponencialmente amortecida. Este tipo de sinal conhecido como "ringdown", e seu comportamento e parametrizao so muito bem conhecidos. Neste trabalho, simulamos computacionalmente sinais provenientes do "ringdown" de buracos negros, com a finalidade de testar o desempenho do detector de ondas gravitacionais Mario Schenberg em observ-los, quando entrar em funcionamento. Este primeiro teste terico ajudou-nos a criar estratgias de deteco de sinais imersos no rudo instrumental. Calculamos a relao sinal-rudo como uma funo da frequncia, bem como sua integral dentro da faixa de sensibilidade do detector. Os resultados obtidos mostraram que o detector Schenberg ter sensibilidade suficiente para detectar este tipo de sinal, proveniente de fontes astrofsicas localizadas dentro de um raio de ~100kpc.
2006-07-01
Brazil has a long tradition in thorium technology, from mineral dressing (monazite) to the nuclear grade thorium compounds. The estimate reserves are 1200,000. ton of ThO{sub 2}. As a consequence from the work of thorium purification pilot plant at Instituto de Pesquisas Energeticas e Nucleares-CNEN/IPEN-SP, about 25 ton of a sludge containing thorium and rare earths was accumulated. It comes as a raffinate and washing solutions from thorium solvent extraction. This sludge, a crude hydroxide named RETOTER contains thorium, rare earths and minor impurities including the radiogenic lead-208, with abundance 88.34 %. This work discusses the results of the studies and main parameters for its recovery by anionic ion exchange technique in the hydrochloric system. The isotope abundance of this lead was analyzed by high resolution mass spectrometer (ICPMS) and thermoionic mass spectrometer (TIMS) and the data was used to calculate the thermal neutron capture cross section. The value of {sigma}{gamma}{sup 0} = 14.6{+-}0.7 mb was found, quite different from the {sigma}{gamma}{sup 0} = 174.2 {+-} 7.0 mb measure cross section for the natural lead. Preliminary study for the thorium and rare earths separation and recovery was discussed as well. (author)
Prottipo do primeiro interfermetro brasileiro - BDA
A interferometria uma poderosa ferramenta usada para investigar estruturas espaciais de fontes astrofsicas fornecendo uma riqueza de detalhes inatingvel pelas tcnicas convencionais de imageamento. Em particular, a interferometria com ondas de rdio abre o horizonte de conhecimento do Universo nesta ampla banda do espectro eletromagntico, que vai de cerca de 20 kHz at centenas de GHz j prximo ao infravermelho, e que est acessvel a partir de instrumentos instalados em solo. Neste trabalho, apresentamos o interfermetro designado por Arranjo Decimtrico Brasileiro (BDA). Trata-se do primeiro interfermetro a ser desenvolvido no Brasil e Amrica Latina que j est em operao na fase de prottipo. Apresentamos o desenvolvimento realizado at o momento, o stio de instalao do instrumento, o prottipo e os principais resultados dos testes de sua operao, as perspectivas futuras e a cincia a ser desenvolvida com o instrumento nas fases II e III. Neste trabalho dada nfase ao desenvolvimento, testes de operao e principais resultados do prottipo. discutida brevemente a cincia que pode ser feita com o instrumento. Tanto os detalhes tcnicos quanto os principais parmetros estimados para o instrumento nas prximas fases de desenvolvimento e o desempenho do prottipo sero publicados em breve.
2009-07-15
Objective: To assess the role of proton magnetic resonance spectroscopy and dynamic contrast-enhanced magnetic resonance imaging in the differentiation between malignant and benign musculoskeletal tumors. Materials And Methods: Fifty-five patients with musculoskeletal tumors (27 malignant and 28 benign) were studied. The examinations were performed in a 1.5 T magnetic resonance scanner with standard protocol, and single voxel proton magnetic resonance spectroscopy with 135 msec echo time. The dynamic contrast study was performed using T1-weighted gradient-echo sequence after intravenous gadolinium injection. Time signal intensity curves and slope values were calculated. The statistical analysis was performed with the Levene's test, followed by a Student's t-test, besides the Pearson's chi-squared and Fischer's exact tests. Results: Proton magnetic resonance spectroscopy sensitivity, specificity and accuracy were, respectively, 87.5%, 92.3% and 90.9% (p < 0.0001). Statistically significant difference was observed in the slope (%/min) between benign (mean, 27.5%/min) and malignant (mean, 110.9%/min) lesions (p < 0.0001). Conclusion: The time-intensity curve and slope values using dynamic-enhanced perfusion magnetic resonance imaging in association with the presence of choline peak demonstrated by single voxel magnetic resonance spectroscopy study are useful in the differentiation between malignant and benign musculoskeletal tumors. (author)
2003-07-01
The Guanabara Bay is the second bigger bay of the Brazilian coast. The bay is one of most beautiful of the world and shelters an ample and protected natural environment, preponderant factor for the development of the region. Due the pollution of this ecosystem, today, the bay represents an important focus of environmental interest. In order to determinate the preservation degree of the organic components of bottom sediments from Guanabara Bay, ninety-two samples were collected from these sediments, however, preliminarily, twenty-five samples were analyzed. These twenty-five samples were submitted to techniques of organic geochemistry (Total Organic Carbon - Toce and Rock- Eval pyrolysis) to determinate the amount and quality of the organic matter, and microscopy (transmitted white light and reflected ultraviolet light). The Toce values of the twenty-five samples range from 0.04 to 6.1% indicating the high preservation degree of the organic matter. The Rock- Eval pyrolysis data show Hydrogen Index (HI) values from 25 to 249 mg HC/gCOT; S1 values ranges from 0,02 to 5,6 mg HC/gR; Production Index (PI) rise up 0,5. The results of the microscopy investigation showed that occur a predominance of amorphous organic matte (AOM) over the palynomorphs and phytoclasts. The liptinitic material showed a light yellow-greenish yellow fluorescence color. The percentages of AOM, the TOC values and fluorescence color indicate a high degree of preservation of the organic matter. The integration of the results from organic geochemistry and microscopy techniques indicate that the sediments of the Baia de Guanabara present very high hydrocarbon pollution, deposited in dysoxic-anoxic environment. (author)
1997-12-01
The onset of fetal thyroid function occurs about 17-18 days after conception in the rat. The maternal hyperthyroidism which occurs during gestation provokes alterations in the rat after its birth; due to this alterations, we decided to analyze the metabolic and hormonal modification in the newborn rats. The hyperthyroidism was induced in normal dams, which were being trated for 2 days with T4 2mg (thyroxine per 100g body wt/day) before mating. Another dam group which was submitted to an inducement of hyperthyroidism maintained the treatment with T4 and six day after gestation were being treated for 9 days. It was seen that the rat which was born from hyperthyroic dams suffered alterations on its T4 and T3 hormone levels concerning the days 10, 20 and 30 after birth. T4 e T3 were performed with Immu chem cooted tube - I{sup 125} RIA KIT .The administration of T4 affected the fetal thyroid function gland to, causing a decrease of both T4 and T3 levels, as was also modifications on their weight and size, even after the birth, indicating that the maternal hyperthyroidism influences on the post-natal life of the rat. The growth is affected throught post-natal life by thyroid hormones, which have a facilitatory influence on GH economy, as opposed to the inhibitory effects on TSH economy. (author). 12 refs., 4 figs.
2003-07-01
During the development of applications of high intensity lasers in the enamel and dentine, adverse thermal effects into the entire dental structure, including the pulp, must be verified. The measurement of the temperature in the intact pulp, however, is not a solved problem. For this purpose, models have been used frequently, using extracted teeth, with pulpal cavities filled with materials that simulate only thermal properties of the pulp. Current models, however, do not simulate optical properties of the pulp, not taking the remaining radiation in the pulp chamber into account. The aim of this study was to verify if the remaining radiation from neodymium and diode lasers that reach the pulp chamber, at the models using extracted bovine teeth, can cause local thermal effects. For this purpose, two models were developed, using extracted bovine teeth with their pulp chambers filled with water (simulating pulp thermal characteristics) without (model 1) and with (model 2) an optical absorbent. Models were radiated with 1 W. The obtained results show that, for both lasers, the temperature rise in model 2 pulp chamber is: up to 11 % higher than in the model 1 when the enamel is radiated; and up to 37% higher than in the model 1 when dentine is radiated (1 mm from the pulp), indicating that the level of the remaining radiation is relevant for the construction of models excited by the neodymium and diode lasers. (author)
Miocene Mammalian footprints in coprolites from Lisbon, Portugal
2006-01-01
ResumoPela primeira vez, pelo menos no concernente à série miocénica de Lisboa (Bacia do Baixo Tejo), foram obtidos dados icnológicos pouco comuns, i.e. pegadas de mamíferos sobre coprólitos, nem sempre produzidas pelos autores dos excrementos. Três coprólitos haviam sido colhidos em outras tantas unidades estratigráficas sucessivas, IVb e Va2 do Miocénico inferior e Vb do princípio do Miocénico médio. A impressão de maior tamanho, tridáctila, é de atribuir ao pé direito de um rinoceronte. As suas modestas dimensões excluem os rinocerontes conhecidos na unidade de proveniência (Vb) excepto Hispanotherium matritensis. Um coprólito mais pequeno (Va2) exibe uma impressão tridáctila do...
2003-07-01
Low intensity GaAlAs ({lambda}=830 nm) laser irradiation effects on oral traumatic ulceration were evaluated. For this purpose, twenty patients presenting orthodontic appliance - induced oral traumatic ulceration were randomly distributed in two groups. Patients in group 1 were submitted to the irradiation procedure and group 2 was the control one. The irradiation parameters employed were the following: wavelength 830 nm, one single application of 4 J/cm{sup 2}, punctual in the contact mode and 30 mW power. The control group received the conventional treatment, consisting on topical application of Triancinolon based ointment four times a day. For both groups the agent responsible for the trauma was removed or covered with utility wax whenever removal was impossible. The results were evaluated concerning the wounds size reduction and pain relief. The time of laser irradiation was considered the starting time (time zero) and analysis were done 24 hours, 48 hours and seven days after that. The statistical analysis showed an acceleration in the healing process as well accentuated pain reduction for the irradiated group compared to the control one. These evidences allows us to indicate this protocol of one single application of 4 J/cm{sup 2} as therapy when patients with oral traumatic ulceration can not attend several sessions for a multiple application procedure. (author)
2005-07-15
Objective: To evaluate the prevalence and appearance of incidental paranasal sinuses abnormalities in children with no clinical evidence of rhino sinusitis using CT scans. Materials and methods: CT scans of the head or orbits of children between 0 and 18 years of age performed due to problems not related to rhino sinusitis were studied. Results: Sixty-four children were included (mean age 5.7 years; standard deviation = 3.9). Incidental sinuses abnormalities were found in 46 cases (72%). In most cases the abnormalities were mild (25/46) and mucosal thickening was the most common finding. Complete opacification and fluid levels occurred in 12 children. More than one cavity was affected in 33 patients and abnormalities were most frequently seen in maxillary sinuses, followed by ethmoid sinuses. Bilateral and symmetric findings were common. The prevalence and intensity of abnormalities were higher in children below three years of age. Conclusion: Incidental abnormalities are highly prevalent and tend to be mild in children without symptoms of rhino sinusitis. The most prevalent abnormality was mucosal thickening. Moderate and severe abnormalities occur in children below three years of age. (author)
2004-03-15
Impact of the nutrients N and K and soluble sugars on Diabrotica speciosa (Germar) (Coleoptera, Chrysomelidae) and Agrotis ipsilon (Huefnagel) (Lepidoptera, Noctuidae) populations in potato crops, Solanum tuberosum L. (Solanaceae). The occurrence of Diabrotica speciosa (Germar, 1824) and Agrotis ipsilon (Huefnagel, 1767) on the potato cultivars Achat and Monalisa, influenced by nitrogen and potassium dosage, and minimum quantity of soluble sugars, was studied. The following parameters were evaluated: concentration of mineral nutrient and sugar in green leaf, senescent leaf, leaf in abscission, stem, tubercle and total plant using extracts of infusion in ethanol 80%. The largest infestation of D. speciosa larvae was on Monalisa cultivar at 150 kg.ha{sup -1} of N + K with 27.03% at P< 0,05. It was observed that the effect of the dosage of N + K in the increment of the concentration of soluble sugars increased the damages in the tubercles and stems by A. ipsilon. The infestation by these species increased to 58.82% on the Monalisa cultivar, when the nitrogen dosage increased from zero to 150 kg.ha{sup -1}, in the absence of potassium. On the other hand, high dosage of K reduced the damages by A. ipsilon on Monalisa cultivar. However, it did not influence the storage of soluble sugar. The results indicated that in Achat cultivar the accumulated soluble sugar was reduced, probably sensitized by elevation of potassic fertilization dosing, differing from Monalisa cultivar, in which the influence was by nitrogen dosing. (author)
Holdup Measurement System II (HMSII): Version 2.1. User`s guide and software documentation
The Holdup Measurement System II (HMSII) software is a database management package for doing Holdup Measurements. It is based on the generalized geometry holdup (GGH) methodology taught in the US Department of Energy Safeguards Technology Training Program, ``Nondestructive Assay of Special Nuclear Materials Holdup.`` This program was developed and taught by Los Alamos National Laboratory (LANL). The HMSII was developed as a joint effort between LANL and the Oak Ridge Y-12 Plant, managed for the US Department of Energy by Lockheed Martin Energy Systems, Inc. The system is designed specifically for use with three types of Multichannel Analyzer (MCA): a Davidson Portable MultiChannel Analyzer (MCA); a EG&G Ortec MicroNOMAD ({mu}NOMAD); or a new Miniature Modular MultiChannel Analyzer (M{sup 3}CA) under development at LANL. It is also designed assuming a 512 channel spectrum from a low resolution (e.g., NaI) detector measuring Uranium or Plutonium. Another important hardware component of the system is a portable bar code reader (also called a DataLogger or Trakker), by Intermec Corporation. The 944X series and the JANUS 2OXX series readers are compatible models with the HMSII. The JANUS series is a bar code reader which is also a 386 compatible palmtop PC with MS-DOS 5.0 built-in. Both series readers are programmable and control all the aspects of field holdup data collection from the MCAs.
Holdup Measurement System II (HMSII): Version 2.1. User`s guide and software documentation
1995-05-31
The Holdup Measurement System II (HMSII) software is a database management package for doing Holdup Measurements. It is based on the generalized geometry holdup (GGH) methodology taught in the US Department of Energy Safeguards Technology Training Program, ``Nondestructive Assay of Special Nuclear Materials Holdup.`` This program was developed and taught by Los Alamos National Laboratory (LANL). The HMSII was developed as a joint effort between LANL and the Oak Ridge Y-12 Plant, managed for the US Department of Energy by Lockheed Martin Energy Systems, Inc. The system is designed specifically for use with three types of Multichannel Analyzer (MCA): a Davidson Portable MultiChannel Analyzer (MCA); a EG&G Ortec MicroNOMAD ({mu}NOMAD); or a new Miniature Modular MultiChannel Analyzer (M{sup 3}CA) under development at LANL. It is also designed assuming a 512 channel spectrum from a low resolution (e.g., NaI) detector measuring Uranium or Plutonium. Another important hardware component of the system is a portable bar code reader (also called a DataLogger or Trakker), by Intermec Corporation. The 944X series and the JANUS 2OXX series readers are compatible models with the HMSII. The JANUS series is a bar code reader which is also a 386 compatible palmtop PC with MS-DOS 5.0 built-in. Both series readers are programmable and control all the aspects of field holdup data collection from the MCAs.
Hexagonal LiMoO/sub 2/: A close-packed layered structure with infinite Mo-Mo-bonded sheets
1988-03-23
A new compound, LiMoO/sub 2/, with hexagonal layered structure has been prepared by reaction of Li/sub 2/MoO/sub 4/ with Mo metal at 900/degree/C for 21 days. Neutron powder diffraction Rietveld analysis shows that LiMoO/sub 2/ is isomorphous with /alpha/-NaFeO/sub 2/; space group /bar R/3m, a = 2.8663 (1) /angstrom/, c = 15.4743 (5) /angstrom/, Z = 3. The structure consists of cubic close-packed oxide layers with Mo and Li atoms occupying octahedral sites between alternate layers. Each Mo atom is thus bonded to six other Mo atoms in a hexagonal sheet with d(Mo-Mo) = 2.8663 (1) /angstrom/. The Mo-O and Li-O distances are 2.0520 (9) and 2.146 (1) /angstrom/, respectively. DOS and COOP curves from extended Hueckel band calculations indicate that all Mo-Mo bonding states are filled within the O-Mo-O slabs. 20 refs., 5 figs., 1 tab.
1992-03-01
Rb-Sr whole-rock analyses of representative granitic rocks from the Bibala-Caraculo region, southwestern Angola, are used to determine the age and evolution of the acid plutonic events in this segment of the Angolan continental crust. The granitoids present a wide range of lithological types and compositions. Three time-intervals have been defined for the magmatism: 1,950 - 1,900 Ma; 1,750 - 1,700 Ma; 1,550 - 1,500 Ma. The oldest, though not very well defined, was obtained for the Chicalengue granitoid, the second one represents the Serra dos Gandarengos and Chonga granitoids and Luchipa-Pungue Granitic Complex and the youngest one comprises the Chicate and Caraculo granitic bodies and Numhino Granitic Complex. The initial {sup 87} Sr/{sup 86} Sr ratios show characteristic values for each time-interval, as follows; 1,950 -1,900 Ma = 0,7015; 1,750 - 1,700 Ma = 0,7060 to 0,7075; 1,550 - 1,500 Ma 0,7048 - 0,7057, suggesting different sources for the granitoids within each geological period. In addition are presented two K-Ar ages for the basic rocks in SW Angola, with values of 1700 and 600 Ma, which represent a minimum ages for these rocks and are probably related to the Damara Orogeny. (author). 24 refs., 11 figs., 2 tabs.
2006-01-01
Motivated by the unconventional properties and rich phase diagram of NaxCoO2 we consider the electronic and magnetic properties of a two-dimensional Hubbard model on an isotropic triangular lattice doped with electrons away from half-filling. Dynamical mean-field theory (DMFT) calculations predict that for negative intersite hopping amplitudes (t 0 a large enhancement of the effective mass, itinerant ferromagnetism, and a metallic phase with a Curie-Weiss magnetic susceptibility are found in a broad electron doping range. The different behavior encountered is a consequence of the larger noninteracting density of states (DOS) at the Fermi level for t > 0 than for t 0 the energy cost of polarizing the system is much smaller than for t T-* and Fermi liquid behavior with enhanced parameters below T-*, where T-* is a low energy coherence scale induced by strong local Coulomb electron correlations. Our analysis also shows that the one band Hubbard model on a triangular lattice is not enough to describe the unusual properties of NaxCoO2 and is used to identify the simplest relevant model that captures the essential physics in NaxCoO2. We propose a model which allows for the Na ordering phenomena observed in the system which, we propose, drives the system close to the Mott insulating phase even at large dopings. Publisher: American Physical Society Contributor: P. D. Adams Coverage: 2006-01-01T00:00:00Z
2001-07-01
This study was carried out to evaluate in vitro the effects of Nd:YAG laser and Er:YAG laser irradiation in the root canal wall by SEM, evaluating the apical leakage and the temperature changes during the laser irradiation. Seventy four extracted human teeth were used, they were instrumented and divided into seven groups of 10 teeth each. The teeth were evaluated through stereoscopy, by SEM, and with the thermographic camera. The Nd:YAG laser irradiation parameters were 100 mJ/p, 15 Hz, and Er:YAG laser were 160 mJ/p and 10 Hz, the irradiation was 4 times at 2 mm/sec speed, with 20 sec interval. The apical leakage was not observed in the teeth irradiated by Nd:YAG laser alone or in association with Er:YAG laser. However in the teeth irradiated only by the Er:YAG laser we observed a little leakage. By SEM observation the Nd:YAG laser irradiation showed melting and recrystallization in the dentin surface closing dentinal tubules, and in the samples irradiated by Er:Y AG laser a clean surface, opened dentinal tubules, and the combination by two lasers, showed melting covering some dentinal tubules The thermographic study found the temperature increase was not more than 6 deg C. This study showed the safety parameters applications of Er:YAG laser in association with Nd:YAG laser in root canal treatment, in order to not cause thermal damages to the periodontal tissues. (author)
1996-12-31
This work shows the results of a monitoring carried out in an area of about 21 km{sup 2}, Dobrada Municipality, central west region of the state of Sao Paulo (Brazil), where the impacts in ground water and surface water were evaluated by the infiltration and percolation of vinasse and water used for washing cane sugar, through accumulation ponds and decantation reservoirs, respectively, in areas of Bauru Aquifer (Cretaceous). The Bauru Aquifer, free and porous, occurs in a extended area of 104.000 km{sup 2} in Sao Paulo State, as a major exploitable aquifer (more than 15.000 wells), used for domestic and industrial water supplies. For the groundwater, the following measures were found in analyses exceeding drinking water standards (WHO; CONAMA/Brazil and Sao Paulo State): manganese (0,03 to 3,5 mg/l), iron (0.45 to 34 mg/l), aluminum (1 to 52 mg/l) and phosphate (0,03 to 0.38 mg/l). For superficial water, the following measures exceeded drinking water standards: total iron (3 mg/l) and phosphate (0,035 mg/l). The main purpose of this research is to improve the field methodology to characterize the impacts of vinasse and washing water of cane sugar infiltration/percolation., detaching the relationship between ground and surface water, with the major aim to supply the legislation to protect drinking water resources. (author) 11 refs.
2004-07-01
Fluoride has been the most important preventive method on development of the caries. This in vivo study evaluated the effects of low-intensity red laser radiation on the fluoride uptake in enamel. Ten healthy participants were recruited for this study. The two maxillary central incisors of each volunteer to be biopsied were used and divided into 4 groups: group G{sub C} (control, which was untreated; group G{sub F} (fluoride), which received topical acidulated phosphate fluoride (APF) 1,23% treatment for 4 minutes; group G{sub LF} (laser + fluoride), which was irradiated with a low-intensity diode laser ({lambda}= 660 nm and dose= 6 J/cm{sup 2}) with APF application after irradiation and group G{sub FL} (fluoride + laser), which received APF before irradiation using the same parameters as G{sub LF}. The determination of fluoride was performed using a fluoride ion electrode after an acid-etch enamel biopsy. The results show a significant increase of the fluoride uptake in enamel for groups G{sub F}, G{sub LF} and G{sub FL} when compared to control group. Although a percentage increase of 57% was observed for G{sub LF} with respect to G{sub F}, there were no statistical differences among treated groups. These findings suggest that low-intensity laser radiation used before APF could be employed in the clinical practice to prevent dental caries. (author)
2004-07-01
The effects of the addition of different level of ZSM-5 additives on different FCC catalysts formulations have been studied on laboratory scale FST (Fluidized Simulation Test). The main objective of the present work is to perform a qualitative identification of the main parameters of FCC catalyst which affect the ZSM-5 additives performance concerning quality and composition of Dry Gas, LPG and Gasoline. The product composition of each test was analyzed by PIANO groups separated by carbon number. The effect of ZSM-5 on products composition was evaluated. The results showed that the ZSM-5 additive cracks gasoline range olefins and isoparaffins into Dry Gas and LPG, favoring the formation of ethylene, propylene and butylenes, while the absolute yield of gasoline aromatics changes little. The aromatics fraction in gasoline, MON and RON numbers in gasoline increase. The ZSM-5 effectiveness is negatively affected by high levels of rare earth on FCC catalyst (RE-USY). Higher hydrogen transfer provides lower olefins (higher than C6) formation, which are the most reactive species for ZSM-5 cracking. (author)
1986-12-31
The carbon influence on the work hardening, formation and reversion of the strain induced martensite and recrystallization of 18%Cr-9%Ni type austenitic stainless steel has been studied using various microstructural analysis techniques. Two alloys were used: One of AISI 304L type, with a low carbon content (%C = 0.021), and one of AISI 304 type, with higher carbon content (%C = 0.065). Both steels were cold rolled and annealed in two different situations: with the carbon totally in solid solution (after solubilization heat treatment at 1100 deg C), and with practically all the carbon precipitated as (Cr,Fe){sub 23} C{sub 6} (after precipitation heat treatment at 750 deg C). The material with higher carbon content, both in solid solution or precipitated, shows higher work hardening, smaller tendency to formation of strain induced martensite and higher recrystallization resistance. The material with carbon in solid solution, in comparison with the precipitated, presents higher work hardening, smaller tendency to formation of strain induced martensite and higher resistance to recrystallization. The nucleation of recrystallization occurred predominantly at the grain boundaries vicinity. The recrystallization kinetics results and the intergranular corrosion tests showed that the usually recommended annealing temperatures (1000 to 1120 deg C) are, in some cases, unnecessarily too high. (author) 8 refs., 7 figs., 2 tabs.
2003-07-01
The accomplishment of hydrostatic tests in pipeline has been used to long years in the certification of the construction methods and assembly. Now with the considerable increase of the installed pipeline, the hydrostatic tests became a tool of significant importance in the evaluation and analysis of the structural integrity of the mesh pipeline. Inserted in this purpose, to CONDUIT it developed an automated system of hydrostatic tests for lines Onshore and Offshore, where the monitoring and registrations, of the essential variables - in 'real team' - such as pressure, temperature, flows and volumes, they made possible to detect leaks, besides the one of small scales, with larger speed and reliability. A supervisory system controlled with PLC's, interlinked the sensor ones and computers, they register and operate the essential variables and the injection of chemical during whole the test, besides generating graphs in 'real team' with inferior input to 5 seconds, making possible the monitoring of several lines, simultaneous and independently. With a system compact, versatile, of easy and fast mobilization, it allows installation in places where the traditional measurement instruments and control are unviable, as uninhabited and automated platforms, points in field open of difficult access, guaranteeing like this continuity and reliability in all of the stages of the test. The application of this technology results in the reduction of work hand and period, bringing reliable necessary results in any situation. (author)
2008-07-01
The assessment of the performance of CaS0{sub 4}:Dy thermoluminescent detectors produced by IPEN in the dosimetry of clinical electron beams aims to propose an alternative to the LiF:Mg,Ti commercial dosimeters (TLD-100) largely applied in radiation therapy. The two types of thermoluminescent dosimeters were characterised with the use of PMMA, RMI-457 type solid water and water phantoms in radiation fields of 4, 6, 9, 12 and 16 MeV electrons of nominal energies in which the dose-response curves were obtained and the surface and depth doses were determined. The thermoluminescent response dependency with the electron nominal energies and the applied phantom were studied. The CaS0{sub 4}:Dy presented the same behaviour than the LiF:Mg,Ti in such a way that its application as an alternative to the TLD-100 pellets in the radiation therapy dosimetry of electron beams is viable and presents the significantly higher sensitivity to the electron radiation as its main advantage. (author)
2004-07-01
The present work analyses the petroliferous productive chain, of the well you the rank. It shows the correlation with the ethics, the social responsibility and the guarantee of the quality of life human being. It considers it lives rational application of paid the resources preceding from royalties you the states and cities. With the reorganization of the petroliferous sector, in the second half of the decade of 90, lives specifically, with the edition of the Law n. 9.478/97, the decisions, until then, prevailed will be unilateral orientates of the federal government starts you count on the market, mediating agent of offers and demand. You the edition of the legal order, you the current days, the excellent facts ploughs dealt with transparency, the teams that if instituted the ANP, agency of regulating to character. The sector, with this, must give counterpart you the society, in the direction you reward the same one, will be possible damages or provoked aggressions, exactly that in involuntary way. Ethical The resolution of the conflicts follows an line of respect you the agents: companies, government and consumers. First with programs of professional qualification, the security, of institutional landmark, they stimulate the perfect competition and applies the exploratory balances in the form of royalties. And, the consumers, not less important, intent to ambient questions, demands quality US products. (author)
Abundncias qumicas de estrelas T Tauri fracas
Apresentamos resultados do estudo de 44 estrelas pr-seqncia principal, para as quais buscamos realizar uma classificao espectroscpica e determinar parmetros estelares e abundncias qumicas. A amostra foi escolhida da seguinte maneira : 21 objetos selecionados a partir de catlogos de objetos jovens, como o Pico dos Dias Survey e o Herbig Bell Catalogue, e 23 objetos selecionados a partir de contrapartidas pticas de fontes de raios X detectadas pelo satlite ROSAT. Dentre 24 objetos previamente classificados como estrelas T Tauri Fracas, apenas 7 revelaram ser realmente pertencentes essa classe, sendo os demais objetos T Tauri Clssicas ou estrelas evoludas da pr-seqncia principal. Esse resultado demonstra que o critrio mais utilizado para distinguir as T Tauri Clssicas das T Tauri Fracas, baseado na largura equivelente da emisso Ha, no suficiente para determinar o estgio evolutivo desses objetos. Para o clculo de parmetros estelares e abundncias, foram escolhidas as estrelas que apresentam caractersticas ideais para esse tipo de estudo, como ausncia de velamento, baixa velocidade de rotao e espectros com razo sinal-rudo adequada. Os parmetros estelares como temperatura efetiva e gravidade foram determinados atravs do equilbrio de excitao e ionizao das linhas de Ferro, e as abundncias qumicas foram calculadas utilizando o mtodo de sntese espectral. Sero apresentados os parmetros estelares e as abundncias de Ltio para toda a amostra, e abundncias de vrios elementos quimicos para 7 estrelas estudadas em maior detalhe
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