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Contribution of Tris Buffer on Xylitol Enzymatic Production

BRANCO, Ricardo de Freitas; SILVA, Silvio S.
Fonte: HUMANA PRESS INC Publicador: HUMANA PRESS INC
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.66%
Xylitol enzymatic production can be an alternative to chemical and microbial processes, because of advantages like higher conversion efficiency. However, for an adequate conversion, it is necessary to investigate the effect of many parameters, such as buffer initial concentration, pH, temperature, agitation, etc. In this context, the objective of this work was to evaluate xylitol enzymatic production under different Tris buffer initial concentrations in order to determine the best condition for this parameter to begin the reaction. The best results were obtained when Tris buffer initial concentration was 0.22 M, reaching 0.31 g L(-1) h(-1) xylitol volumetric productivity with 99% xylose-xylitol conversion efficiency. Although the increase in buffer concentration allowed better pH maintenance, it hindered the catalysis. The results demonstrate that this bioreaction is greatly influenced by involved ions concentrations.; Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)[2005/02840-0]; Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)[2005/02866-9]; Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES); Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)

Saliva flow rate, buffer capacity, and pH of autistic individuals

BASSOUKOU, Ivy Haralambos; NICOLAU, Jose; SANTOS, Maria Teresa dos
Fonte: SPRINGER HEIDELBERG Publicador: SPRINGER HEIDELBERG
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
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The objective of the study was to evaluate saliva flow rate, buffer capacity, pH levels, and dental caries experience (DCE) in autistic individuals, comparing the results with a control group (CG). The study was performed on 25 noninstitutionalized autistic boys, divided in two groups. G1 composed of ten children, ages 3-8. G2 composed of 15 adolescents ages 9-13. The CG was composed of 25 healthy boys, randomly selected and also divided in two groups: CG3 composed of 14 children ages 4-8, and CG4 composed of 11 adolescents ages 9-14. Whole saliva was collected under slight suction, and pH and buffer capacity were determined using a digital pHmeter. Buffer capacity was measured by titration using 0.01 N HCl, and the flow rate expressed in ml/min, and the DCE was expressed by decayed, missing, and filled teeth (permanent dentition [DMFT] and primary dentition [dmft]). Data were plotted and submitted to nonparametric (Kruskal-Wallis) and parametric (Student`s t test) statistical tests with a significance level less than 0.05. When comparing G1 and CG3, groups did not differ in flow rate, pH levels, buffer capacity, or DMFT. Groups G2 and CG4 differ significantly in pH (p = 0.007) and pHi = 7.0 (p = 0.001), with lower scores for G2. In autistic individuals aged 3-8 and 9-13...

Análise dos aspectos jurídicos correlatos à zona de amortecimento de unidades de conservação: estudo de caso da Estação Ecológica de Assis (SP); Legal aspects regarding the buffer zone of protected areas: case study of Assis Ecological Station (São Paulo State, Brazil)

Vitalli, Patrícia de Luca
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 31/08/2007 Português
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As figuras das zonas de entorno e de amortecimento de unidades de conservação foram criadas em lei como áreas submetidas a limitações administrativas, nas quais devem ser impedidas ou regulamentadas atividades que ofereçam ameaça aos recursos naturais dos ecossistemas protegidos. A eficácia desses instrumentos jurídicos, porém, é discutível e foi objeto do presente estudo, tratando de um estudo de caso, na Estação Ecológica de Assis, situada no sudoeste do Estado de São Paulo, enquadrada como unidade de proteção integral, pertencente ao Instituto Florestal, órgão este subordinado à Secretaria de Estado Meio Ambiente. O estudo foi realizado com os seguintes objetivos: 1) proceder análise da legislação que trata do assunto, para tornar clara a natureza jurídica da zona de entorno e zona de amortecimento de unidades de conservação; 2) identificar as atividades humanas impactantes já existentes na zona de entorno da Estação Ecológica de Assis, hierarquizá-las segundo o nível de ameaça que oferecem e apontar possíveis soluções; 3) avaliar a eficácia da norma que estabelece o procedimento licenciatório em, efetivamente, impedir que sejam instaladas novas obras ou atividades impactantes na zona de entorno da EEcA. O levantamento das ameaças baseou-se em diagnóstico pré-existente...

Dinâmica de uso das terras nos municípios de Bonito, Jardim e Bodoquena (MS) e o estado e conservação dos recursos biológicos do Parque Nacional da Serra da Bodoquena e de sua zona de amortecimento; Spatial and temporal dynamics of land use in Bonito, Jardim and Bodoquena (MS) Municipalities, and the conservation state of the biological resources in the Serra da Bodoquena National Park buffer zone

Silva, Normandes Matos da
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 31/03/2008 Português
Relevância na Pesquisa
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A pesquisa abordou o processo de uso e ocupação das terras nos municípios de Bodoquena, Bonito e Jardim, situados na borda leste do Parque Nacional da Serra da Bodoquena (PNSB), região sudoeste de Mato Grosso do Sul. Além disso, foi estudado o estado de conservação, em termos de estrutura e configuração da paisagem, dos remanescentes de cerrado e floresta contidos no interior do PNSB e em sua zona de amortecimento. O objetivo foi o de analisar a dinâmica de ocupaçao das terras nos municípios mencionados nos últimos 18 anos, com vistas à subsidiar estratégias de planejamento do uso e ocupação das terras ideal para a região. Objetivou-se também analisar a dinâmica espacial e temporal da paisagem que compõe o PNSB e sua zona de amortecimento, visando à conservação da biodiversidade local. Para isso, foi utilizado um sistema de informação geográfica (SIG) para elaboração de mapas temáticos e de um banco de dados georreferenciado. A determinação do grau de conservação do PNSB e da sua zona de amortecimento se deu mediante a utilização de métricas de paisagem, e da adoção dos preceitos da Teoria dos Grafos. O capítulo 1 demonstrou, por meio dos mapas gerados para os municípios de Bodoquena, Jardim e Bonito...

Heurística evolutiva para a minimização do atraso total em ambiente de produção Flow Shop com buffer zero; Evolutionary heuristic for total tardiness minimization in Flow Shop environment with no Buffer

Komesu, Adriano Seiko
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 10/04/2015 Português
Relevância na Pesquisa
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Este trabalho aborda o problema de programação de tarefas, a partir de um caso específico, conhecido como Flow Shop com buffer zero. O problema consiste em programar n tarefas em m máquinas no ambiente Flow Shop permutacional. Com o aumento do nível de exigência dos clientes, pesquisas que buscam o atendimento das datas de entrega têm se tornado de extrema importância em ambientes de manufatura. Este trabalho analisa o problema de minimização do atraso total no ambiente Flow Shop onde não existe a possibilidade de armazenagem das tarefas entre estágios de produção sucessivos (buffer zero), tendo como consequência o bloqueio de máquinas. A Heurística Evolutiva Clustering Search foi proposta e analisada para a obtenção de soluções de altíssima qualidade para o problema. Finalmente, uma extensa experimentação computacional foi realizada. Quando comparado com o melhor método reportado na literatura, o método proposto apresentou qualidade superior.; This work deals with the Flow Shop scheduling problem. The objective is scheduling n jobs on m machines in the Permutation Flow Shop environment. With the increasing customer demand level, researches that aims the attendance of due dates have become extremely important in manufacturing process. This work studies the total tardiness minimization problem in the flow shop environment where there is no buffer storage between machines...

Estudo sobre a exploração de vulnerabilidades via estouros de buffer sobre mecanismos de proteção e suas fraquezas; Study about the exploitation of vulnerabilities through buffer overflow, about protection mechanisms and their weaknesses

Martins, Helder Garay
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Trabalho de Conclusão de Curso Formato: application/pdf
Português
Relevância na Pesquisa
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Este trabalho tem como objetivo apresentar detalhadamente o que são, como ocorrem e os riscos dos ataques baseados em estouros de buffer. Também faz parte da proposta deste artigo analisar a ferramenta Stack-Smashing Protector usada para proteger contra essas explorações, detalhar seu funcionamento e apresentar suas vulnerabilidades. Estouro de buffer é uma forma de ataque baseado na exploração do mal uso de funções que manipulam arrays. Esta vulnerabilidade pode estar presente em linguagens que não verificam automaticamente se os limites de memória alocada para uma variável foram respeitados durante a execução do programa. Stack-Smashing Protector (SSP) é uma das ferramentas mais utilizadas atualmente para impedir ou dificultar a exploração de estouros de buffer para a linguagem C. Sistemas operacionais modernos o utilizam como ferramenta padrão para evitar brechas de segurança em programas compilados em seu domínio. Inicialmente, serão apresentados conceitos essenciais para o bom entendimento do tema. A seguir, os métodos usados para executar a exploração serão estudados minuciosamente. Após, a exploração será posta em prática em programas que apresentam tal vulnerabilidade. Por fim, serão analisados detalhes de implementação da ferramenta SSP e os possíveis cenários existentes para burlá-la.; This paper aims to present in detail what are...

Nitrous oxide production and potential denitrification in soils from riparian buffer strips: Influence of earthworms and plant litter

Bradley, R. L.; Whalen, J.; Chagnon, P. -L.; Lanoix, M.; Alves, M. C.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica
Português
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Vegetated riparian buffer strips have been established in Southern Quebec (Canada) in order to intercept nutrients such as nitrate (NO(3)(-)) and protect water quality near agricultural fields. Buffer strips may also favour denitrification through a combination of high soil moisture, NO(3)(-) and carbon supply, which could lead to the production of nitrous oxide (N(2)O), a greenhouse gas. Denitrification could be further amplified by the presence of earthworms, or by plant species that promote earthworm and bacterial activity in soils. Soils from four farms, comprising maize fields and adjacent buffer strips, were sampled in the fall of 2008. A total of six earthworm species were found, but average earthworm biomass did not differ between buffer strips and maize agroecoecosystems. Nitrate concentrations and net nitrification rates were higher in the maize fields than in the buffer strips: there was no difference in N(2)O production in soils collected from the two sampling locations. Potential denitrification, measured by acetylene inhibition, varied by two orders of magnitude, depending on experimental conditions: when amended with H(2)O or with H(2)O + NO3-, potential denitrification was higher (P < 0.05) in soils from buffer strips than from maize fields. Potential denitrification was highest in soils amended with H(2)O+glucose...

Ferroelectric and structural instability of (Pb,Ca)TiO3 thin films prepared in an oxygen atmosphere and deposited on LSCO thin films which act as a buffer layer

Pontes, D. S L; Pontes, F. M.; Pereira-da-Silva, Marcelo A.; Zampieri, M.; Chiquito, A. J.; Pizani, P. S.; Longo, Elson
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica
Português
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Structural, microstructural and ferroelectric properties of Pb0.90Ca0.10TiO3 (PCT10) thin films deposited using La0.50Sr0.50CoO3 (LSCO) thin films which serve only as a buffer layer were compared with properties of the thin films grown using a platinum-coated silicon substrate. LSCO and PCT10 thin films were grown using the chemical solution deposition method and heat-treated in an oxygen atmosphere at 700 °C and 650 °C in a tube oven, respectively. X-ray diffraction (XRD) and Raman spectroscopy results showed that PCT10 thin films deposited directly on a platinum-coated silicon substrate exhibit a strong tetragonal character while thin films with the LSCO buffer layer displayed a smaller tetragonal character. Surface morphology observations by atomic force microscopy (AFM) revealed that PCT10 thin films with a LSCO buffer layer had a smoother surface and smaller grain size compared with thin films grown on a platinum-coated silicon substrate. Additionally, the capacitance versus voltage curves and hysteresis loop measurement indicated that the degree of polarization decreased for PCT10 thin films on a LSCO buffer layer compared with PCT10 thin films deposited directly on a platinum-coated silicon substrate. This phenomenon can be described as the smaller shift off-center of Ti atoms along the c-direction 〈001〉 inside the TiO6 octahedron unit due to the reduction of lattice parameters. Remnant polarization (P r ) values are about 30 μC/cm2 and 12 μC/cm2 for PCT10/Pt and PCT10/LSCO thin films...

Emprego do método Z-Buffer modificado na detecção de oclusões de edificações para geração de ortoimagens verdadeiras

Mendonça Júnior,Marcis Gualberto; Mitishita,Edson Aparecido
Fonte: Universidade Federal do Paraná Publicador: Universidade Federal do Paraná
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2011 Português
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36.66%
O uso de modelos digitais de superfície (MDS) aliado a existência de áreas oclusas faz com que, na geração de ortoimagens verdadeiras, ocorra a formação de um fenômeno conhecido como "duplo mapeamento". Para evitá-lo é necessária à detecção das áreas oclusas existentes, e o método mais utilizado na atualidade tem origem na Computação Gráfica, e se denomina Método Z-Buffer. Esse artigo apresenta a implementação de algoritmos para ortorretificação de fotografias aéreas, com emprego do método inverso, e para detecção de áreas oclusas, com base em uma modificação do Z-Buffer, denominada de Método Z-Buffer Modificado. Como áreas de estudo foram utilizadas duas áreas da cidade de Curitiba - PR, que possuíam recobrimento fotogramétrico e MDS disponíveis. Os resultados obtidos possibilitaram identificar o comportamento do Método Z-Buffer Modificado na detecção das áreas oclusas, e como sua principal limitação, denominada de Porção M, influência na supressão dos Duplos Mapeamentos formados durante a geração das ortoimagens verdadeiras.

Optimization approaches to mpi and area merging-based parallel buffer algorithm

Fan,Junfu; Ji,Min; Gu,Guomin; Sun,Yong
Fonte: Universidade Federal do Paraná Publicador: Universidade Federal do Paraná
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2014 Português
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On buffer zone construction, the rasterization-based dilation method inevitably introduces errors, and the double-sided parallel line method involves a series of complex operations. In this paper, we proposed a parallel buffer algorithm based on area merging and MPI (Message Passing Interface) to improve the performances of buffer analyses on processing large datasets. Experimental results reveal that there are three major performance bottlenecks which significantly impact the serial and parallel buffer construction efficiencies, including the area merging strategy, the task load balance method and the MPI inter-process results merging strategy. Corresponding optimization approaches involving tree-like area merging strategy, the vertex number oriented parallel task partition method and the inter-process results merging strategy were suggested to overcome these bottlenecks. Experiments were carried out to examine the performance efficiency of the optimized parallel algorithm. The estimation results suggested that the optimization approaches could provide high performance and processing ability for buffer construction in a cluster parallel environment. Our method could provide insights into the parallelization of spatial analysis algorithm.

Creating a Replicable, Valid Cross-Platform Buffering Technique: The Sausage Network Buffer for Measuring Food and Physical Activity Built Environments

Forsyth, Ann; Van Riper, David; Larson, Nicole; Wall, Melanie; Neumark-Sztainer, Dianne
Fonte: Springer Science + Business Media Publicador: Springer Science + Business Media
Tipo: Artigo de Revista Científica
Português
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Background Obesity researchers increasingly use geographic information systems to measure exposure and access in neighborhood food and physical activity environments. This paper proposes a network buffering approach, the “sausage” buffer. This method can be consistently and easily replicated across software versions and platforms, avoiding problems with proprietary systems that use different approaches in creating such buffers. Methods In this paper, we describe how the sausage buffering approach was developed to be repeatable across platforms and places. We also examine how the sausage buffer compares with existing alternatives in terms of buffer size and shape, measurements of the food and physical activity environments, and associations between environmental features and health-related behaviors. We test the proposed buffering approach using data from EAT 2010 (Eating and Activity in Teens), a study examining multi-level factors associated with eating, physical activity, and weight status in adolescents (n = 2,724) in the Minneapolis/St. Paul metropolitan area of Minnesota. Results Results show that the sausage buffer is comparable in area to the classic ArcView 3.3 network buffer particularly for larger buffer sizes. It obtains similar results to other buffering techniques when measuring variables associated with the food and physical activity environments and when measuring the correlations between such variables and outcomes such as physical activity and food purchases. Conclusions Findings from various tests in the current study show that researchers can obtain results using sausage buffers that are similar to results they would obtain by using other buffering techniques. However...

Cooling, Collisions and non-Sticking of Polyatomic Molecules in a Cryogenic Buffer Gas Cell

Piskorski, Julia Hege
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation
Português
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We cool and study trans-Stilbene, Nile Red and Benzonitrile in a cryogenic (7K) cell filled with low density helium buffer gas. No molecule-helium cluster formation is observed, indicating limited atom-molecule sticking in this system. We place an upper limit of 5% on the population of clustered He-trans-Stilbene, consistent with a measured He-molecule collisional residence time of less than (1 mu s). With several low energy torsional modes, trans-Stilbene is less rigid than any molecule previously buffer gas cooled into the Kelvin regime. We report cooling and gas phase visible spectroscopy of Nile Red, a much larger molecule. Our data suggest that buffer gas cooling will be feasible for a variety of small biological molecules. The same cell is also ideal for studying collisional relaxation cross sections. Measurements of Benzonitrile vibrational state decay results in determination of the vibrational relaxation cross sections of (sigma_{22} = 8x10^{-15} cm^2) and (sigma_{21} = 6x10^{-15} cm^2) for the 22 (v=1) and 21 (v=1) states. For the first time, we directly observe formation of cold molecular dimers in a cryogenic buffer gas cell and determine the dimer formation cross section to be (sim10^{-13} cm^2).; Physics

Buffer overflow: teoria e exploração

Fonte: Universidade Federal de Lavras Publicador: Universidade Federal de Lavras
Tipo: Trabalho de Conclusão de Curso
Português
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This work is a study about buffer overflow, presenting the architectures of the software and hardware involved. It explains the architectures of the Intel 64 and IA-32 processors, as well as the Linux operating system. These environments were used for the development and exploration of buffer overflow. The problem is detailed and some studies cases shown, exemplifying your exploitation. Basically, buffer overflow occurs during writing in memory regions or arrays. There is interest in show how negligence with computing security during software development can be dangerous for computing environments. The study comments about some of the existing tools to prevent buffer overflow on the Linux operating system. These tools are applied to different contexts and have some level of security; the tools examined are: Libsafe, StackGuard, StackShield, ProPolice and PaX. The larger problem of buffer overflow is mistakes made during development phase. In experiments, it was possible to invade a 32 bits system through attacks in the following overwriting modes: return address and base pointer frame of calling function, and function pointer. On the other hand, it was not possible to exploit the fault in a 64 bits system.

Investigation of the effect of a buffer layer on the magnetic properties of soft materials

Sina, Soltanmohammad
Fonte: Univesity of Limerick Publicador: Univesity of Limerick
Tipo: info:eu-repo/semantics/masterThesis; all_ul_research; ul_published_reviewed; ul_theses_dissertations
Português
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peer-reviewed; In this thesis, we study the influence of a buffer layer (Ta, Cr, W, Ti) on the structure formation, crystallographic orientation, resistivity and magnetic properties of NiFe alloy in the form of bilayer and multilayer nanostructures. In addition, we also investigate how these physical properties are affected by the buffer layer thickness (from 50 nm to 200 nm), the sputtering gas pressure and the applied magnetic field during deposition. All nanostructures were prepared by sputtering onto oriented Si substrates. The overall aim of this work is to obtain nanostructures with small coercivities and identify the required relevant structural parameters. The structure of the films was analyzed using symmetric and asymmetric X-ray diffraction (XRD). XRD results showed that NiFe films are formed preferentially with a fcc crystalline structure. The structure does not depend on the buffer layer material. However, we observed changes in texture when the thickness of the tantalum buffer layer was increased. Our experiments showed that the changes in thickness for buffer layers of other materials did not affect the crystallographic orientation of the NiFe films. For a tantalum buffer layer, the (111) texture of NiFe is favored in thin layers and is reduced as layer buffer thickness increases. Magnetic measurements using Vibrating Sample Magnetometer (VSM) also showed that films with a 50 nm Ta buffer layer exhibited the lowest hard axis coercivity of about 1.70 ± 0.06 Oe compared to other buffer layer materials with the same thickness. The effect...

Tight Bounds for Prefetching and Buffer Management Algorithms for Parallel I/O Systems

Varman, Peter J.; Verma, Rakesh M.
Fonte: Rice University Publicador: Rice University
Tipo: Journal article; Text
Português
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The I/O performance of applications in multiple-disk systems can be improved by overlapping disk accesses. This requires the use of appropriate prefetching and buffer management algorithms that ensure the most useful blocks are accessed and retained in the buffer. In this paper, we answer several fundamental questions on prefetching and buffer management for distributed-buffer parallel I/O systems. First, we derive and prove the optimality of an algorithm, P-min, that minimizes the number of parallel I/Os. Second, we analyze P-con, an algorithm that always matches its replacement decisions with those of the well-known demand-paged MIN algorithm. We show that P-con can become fully sequential in the worst case. Third, we investigate the behavior of on-line algorithms for multiple-disk prefetching and buffer management. We define and analyze P-lru, a parallel version of the traditional LRU buffer management algorithm. Unexpectedly, we find that the competitive ratio of P-lru is independent of the number of disks. Finally, we present the practical performance of these algorithms on randomly generated reference strings. These results confirm the conclusions derived from the analysis on worst case inputs.

Tasks for assessment of the episodic buffer: a systematic review

Nobre,Alexandre de Pontes; Rodrigues,Jaqueline de Carvalho; Sbicigo,Juliana Burges; Piccolo,Luciane da Rosa; Zortea,Maxciel; Duarte Junior,Sérgio; Salles,Jerusa Fumagalli de
Fonte: Pontificia Universidade Católica do Rio de Janeiro; Universidade de Brasília; Universidade de São Paulo Publicador: Pontificia Universidade Católica do Rio de Janeiro; Universidade de Brasília; Universidade de São Paulo
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2013 Português
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The aim of the present study was to review the tasks that have been used to assess the functioning of the episodic buffer in Baddeley's multicomponent model of working memory. A systematic review of studies published from January 2000 to February 2013 was conducted. The search term "episodic buffer" was used in the Web of Knowledge, PsycINFO, PubMed, Embase, and BVS-Psi databases. The selected articles consisted of empirical studies that used tasks to assess the episodic buffer. Theoretical and review papers and studies with animals were excluded. The final sample comprised 36 papers. The tasks were categorized as experimental tasks or standardized tests. The experimental tasks were grouped by modality (unimodal or crossmodal) and described according to four criteria: task to be performed, type of stimulus used, secondary task employed, if any, and retention interval. The standardized tests included classical measures of working memory. Some tasks were found not to meet experimental criteria that were needed to evaluate the episodic buffer. Moreover, some of the standardized tests did not provide theoretical arguments or empirical evidence that the episodic buffer is recruited to perform them. The results are discussed in the context of the multicomponent model of working memory.

The RIT IEEE-488 buffer design

Connor, John
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
Português
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This document describes the design of an NMOS ASIC used to control an RIT IEEE-488 Buffer previously designed by the author. Past designs used discrete components to implement an asynchronous controller and a synchronous, one-hot controller. The present design utilizes a multiple controller architecture incorporated within the ASIC. The ASIC is used to control bus protocol, bus transceivers, and memory. At power-up, the buffer configures itself as an active listener on the bus and waits for a talker to initiate communication. The buffer accepts a data file (a plot file for example) from the talker, then takes control of the bus, addresses a listener, transfers the stored data to the listener, unaddresses the listener, releases the bus, and finally, reassumes the active listener configuration. The RIT IEEE-488 buffer can realize time savings for a user in a controllerless system. The buffer accepts data from a talker in a matter of seconds and then takes on the chore of driving a slow listener. Thus, the talker is returned quickly to the operator for further use. At present, the buffer isn't queueable - it cannot accept another data file until it completes the transfer of the present file. The author has also added five nmos cells (schematic/layout) into the '/user/pub' directory on the Apollo workstations in the Computer Engineering Department's VLSI LAB at RIT. Cell names are VSCLK...

Calcium dynamics, buffering, and buffer saturation in the boutons of dentate granule-cell axons in the Hilus

Redman, Stephen
Fonte: Society for Neuroscience Publicador: Society for Neuroscience
Tipo: Artigo de Revista Científica
Português
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The axons of dentate gyrus granule cells form synapses in the hilus. Ca2+ signaling was investigated in the boutons of these axons using confocal fluorescence imaging. Boutons were loaded with various concentrations of the Ca2+ indicator Oregon Green BAPTA-1 by patch-clamping the cell bodies and allowing the dye to diffuse into the axon. Resting free [Ca2+] started at 74 nM, rose to ∼1 μM immediately after an action potential, and then decayed to rest with a time constant of 43 msec (all extrapolated to a dye concentration of zero). Action potential-induced [Ca2+] rises were smaller in larger boutons, consistent with a size-independent Ca2+ channel density of 45/μm2. Action potential-induced [Ca2+] changes varied with dye concentration in a manner consistent with ΚE∼20 for the ratio of endogenous buffer-bound Ca2+ to free Ca2+. During trains of action potentials, [Ca2+] increments summed supralinearly by more than that expected from dye saturation. The amount of endogenous Ca2+ buffering declined as [Ca2+] rose, and this saturation indicated a buffer with a dissociation constant of ∼500 nM and a concentration of ∼130 μM. This is similar to the dissociation constant of calbindin-D28K, a Ca2+-binding protein that is abundant in dentate granule cells. Thus...

EMPREGO DO MÉTODO Z-BUFFER MODIFICADO NA DETECÇÃO DE OCLUSÕES DE EDIFICAÇÕES PARA GERAÇÃO DE ORTOIMAGENS VERDADEIRAS

MENDONÇA JÚNIOR, MARCIS GUALBERTO; UFPR; MITISHITA, EDSON APARECIDO
Fonte: Universidade Federal do Paraná-UFPR Publicador: Universidade Federal do Paraná-UFPR
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Artigo Avaliado pelos Pares Formato: application/pdf
Publicado em 02/04/2011 Português
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O uso de modelos digitais de superfície (MDS) aliado a existência de áreas oclusas faz com que, na geração de ortoimagens verdadeiras, ocorra a formação de um fenômeno conhecido como “duplo mapeamento”. Para evitá-lo é necessária à detecção das áreas oclusas existentes, e o método mais utilizado na atualidade tem origem na Computação Gráfica, e se denomina Método  Z-Buffer. Esse artigo apresenta a implementação de algoritmos para ortorretificação de fotografias aéreas, com emprego do método inverso, e para detecção de áreas oclusas, com base em uma modificação do Z-Buffer, denominada de Método Z-Buffer Modificado. Como áreas de estudo foram utilizadas duas áreas da cidade de Curitiba – PR, que possuíam recobrimento fotogramétrico e MDS disponíveis. Os resultados obtidos possibilitaram identificar o comportamento do Método  Z-Buffer Modificado na detecção das áreas oclusas, e como sua principal limitação, denominada de Porção M...

OPTIMIZATION APPROACHES TO MPI AND AREA MERGING-BASED PARALLEL BUFFER ALGORITHM

FAN, JUNFU; Institute of Geographic and Nature Resources Research; JI, MIN; University of Science and Technology; GU, GUOMIN; Zhejiang University of Technology; SUN, YONG; University of Science and Technology
Fonte: Universidade Federal do Paraná-UFPR Publicador: Universidade Federal do Paraná-UFPR
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Artigo Avaliado pelos Pares Formato: application/pdf
Publicado em 11/06/2014 Português
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On buffer zone construction, the rasterization-based dilation method inevitablyintroduces errors, and the double-sided parallel line method involves a series ofcomplex operations. In this paper, we proposed a parallel buffer algorithm based onarea merging and MPI (Message Passing Interface) to improve the performances ofbuffer analyses on processing large datasets. Experimental results reveal that thereare three major performance bottlenecks which significantly impact the serial andparallel buffer construction efficiencies, including the area merging strategy, thetask load balance method and the MPI inter-process results merging strategy.Corresponding optimization approaches involving tree-like area merging strategy, the vertex number oriented parallel task partition method and the inter-processresults merging strategy were suggested to overcome these bottlenecks. Experimentswere carried out to examine the performance efficiency of the optimized parallelalgorithm. The estimation results suggested that the optimization approaches couldprovide high performance and processing ability for buffer construction in a clusterparallel environment. Our method could provide insights into the parallelization ofspatial analysis algorithm.