Página 19 dos resultados de 20101 itens digitais encontrados em 0.013 segundos

‣ Homology Modeling of the CheW Coupling Protein of the Chemotaxis Signaling Complex

Cashman, Derek J.; Ortega, Davi R.; Zhulin, Igor B.; Baudry, Jerome
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 07/08/2013 Português
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Homology models of the E. coli and T. maritima chemotaxis protein CheW were constructed to assess the quality of structural predictions and their applicability in chemotaxis research: i) a model of E. coli CheW was constructed using the T. maritima CheW NMR structure as a template, and ii) a model of T. maritima CheW was constructed using the E. coli CheW NMR structure as a template. The conformational space accessible to the homology models and to the NMR structures was investigated using molecular dynamics and Monte Carlo simulations. The results show that even though static homology models of CheW may be partially structurally different from their corresponding experimentally determined structures, the conformational space they can access through their dynamic variations can be similar, for specific regions of the protein, to that of the experimental NMR structures. When CheW homology models are allowed to explore their local accessible conformational space, modeling can provide a rational path to predicting CheW interactions with the MCP and CheA proteins of the chemotaxis complex. Homology models of CheW (and potentially, of other chemotaxis proteins) should be seen as snapshots of an otherwise larger ensemble of accessible conformational space.

‣ Evaluating minimalist mimics by exploring key orientations on secondary structures (EKOS)☟

Xin, Dongyue; Ko, Eunhwa; Perez, Lisa M.; Ioerger, Thomas R.; Burgess, Kevin
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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Peptide mimics that display amino acid side-chains on semi-rigid scaffolds (not peptide polyamides) can be referred to as minimalist mimics. Accessible conformations of these scaffolds may overlay with secondary structures giving, for example, “minimalist helical mimics”. It is difficult for researchers who want to apply minimalist mimics to decide which one to use because there is no widely accepted protocol for calibrating how closely these compounds mimic secondary structures. Moreover, it is also difficult for potential practitioners to evaluate which ideal minimalist helical mimics are preferred for a particular set of side-chains. For instance, what mimic presents i, i+4, i+7 side-chains in orientations that best resemble an ideal α-helix, and is a different mimic required for a i, i+3, i+7 helical combination? This article describes a protocol for fitting each member of an array of accessible scaffold conformations on secondary structures. The protocol involves: (i) use quenched molecular dynamics (QMD) to generate an ensemble consisting of hundreds of accessible, low energy conformers of the mimics; (ii) representation of each of these as a set of Cα and Cβ coordinates corresponding to three amino acid side-chains displayed by the scaffolds;(iii) similar representation of each combination of three side-chains in each ideal secondary structure as a set of Cα and Cβ coordinates corresponding to three amino acid side-chains displayed by the scaffolds; and...

‣ The CDC Hemophilia B mutation project mutation list: a new online resource

Li, Tengguo; Miller, Connie H; Payne, Amanda B; Craig Hooper, W
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
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Hemophilia B (HB) is caused by mutations in the human gene F9. The mutation type plays a pivotal role in genetic counseling and prediction of inhibitor development. To help the HB community understand the molecular etiology of HB, we have developed a listing of all F9 mutations that are reported to cause HB based on the literature and existing databases. The Centers for Disease Control and Prevention (CDC) Hemophilia B Mutation Project (CHBMP) mutation list is compiled in an easily accessible format of Microsoft Excel and contains 1083 unique mutations that are reported to cause HB. Each mutation is identified using Human Genome Variation Society (HGVS) nomenclature standards. The mutation types and the predicted changes in amino acids, if applicable, are also provided. Related information including the location of mutation, severity of HB, the presence of inhibitor, and original publication reference are listed as well. Therefore, our mutation list provides an easily accessible resource for genetic counselors and HB researchers to predict inhibitors. The CHBMP mutation list is freely accessible at http://www.cdc.gov/hemophiliamutations.

‣ Characterization of human placental glycosaminoglycans and regional binding to VAR2CSA in malaria infected erythrocytes

Beaudet, Julie M.; Mansur, Leandra; Joo, Eun Ji; Kamhi, Eyal; Yang, Bo; Clausen, Thomas M; Salanti, Ali; Zhang, Fuming; Linhardt, Robert J.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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Placental malaria is a serious problem in sub-Saharan Africa. Young women are particular susceptible to contracting this form of malaria during their first or second pregnancy despite previously acquired immunity from past infections. Placental malaria is caused by Plasmodium falciparum parasites expressing VAR2CSA on the erythrocyte surface. This protein adheres to a low-sulfated chondroitin sulfate-A found in placental tissue causing great harm to both mother and developing fetus. In rare cases, the localization of infected erythrocytes to the placenta can even result in the vertical transmission of malaria. In an effort to better understand this infection, chondroitin sulfate was isolated from the cotyledon part of the placenta, which should be accessible for parasite adhesion, as well as two non-accessible parts of the placenta to serve as controls. The placental chondroitin sulfate structures and their VAR2CSA binding were characterized. All portions of human placenta contained sufficient amounts of the appropriate low-sulfated chondroitin sulfate-A to display high-affinity binding to a recombinant truncated VAR2CSA construct, as determined using surface plasmon resonance. The cotyledon is the only placental tissue accessible to parasites in the bloodstream...

‣ The View of Nurses toward Prioritizing the Caring Behaviors in Cancer Patients

Valizadeh, Leila; Zamanzadeh, Vahid; Azimzadeh, Roghaieh; Rahmani, Azad
Fonte: Tabriz University of Medical Sciences Publicador: Tabriz University of Medical Sciences
Tipo: Artigo de Revista Científica
Publicado em 26/05/2012 Português
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Introduction: There are many opportunities for nurses to assist improving patient’s ex-perience of cancer. In fact, in every stage of cancer process, nurses can provide the re-quired and necessary cares and supports by representing substantial caring behaviors. Thus, by identifying and understanding the importance of caring behaviors which led to nurse-patient effective interactions, nurses would be able to care better for patients and so to enhance patients’ satisfaction toward nursing services. However, a few studies have ever been done about perception of oncology nurses about prioritization of caring behaviors. Methods: This was a descriptive study done among all the nurses of oncology wards (n = 40) in Shahid-Ghazi-Tabatabaei Hospital of Tabriz in 2009. Data collection performed using Larson’s CARE-Q tool that assessed the importance of caring beha-viors in six subscales as the following: “Monitors and follows through”, “Explains and facilitates”, “Physical and emotional comforts”, “Trusting relationship”, “Anticipates” and “Being accessible”. Results: In this study, the importance of caring behaviors was evaluated in moderate to high level and the priorities of care dimensions were deter-mined. “Monitors and follows through” and “Being accessible” received a high priority and “Anticipates”...

‣ Building and Accessing Clausal Representations: The Advantage of First Mention versus the Advantage of Clause Recency

Gernsbacher, Morton Ann; Hargreaves, David J.; Beeman, Mark
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1989 Português
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We investigated two seemingly contradictory phenomena: the Advantage of the First-Mentioned Participant (participants mentioned first in a sentence are more accessible than participants mentioned second) and the Advantage of the Most Recent Clause (concepts mentioned in the most recent clause are more accessible than concepts mentioned in an earlier clause). We resolved this contradiction by measuring how quickly comprehenders accessed participants mentioned in the first versus second clauses of two-clause sentences. Our data supported the following hypotheses: Comprehenders represent each clause of a two-clause sentence in its own mental substructure. Comprehenders have greatest access to information in the substructure that they are currently developing; that is, they have greatest access to the most recent clause. However, at some point, the first clause becomes more accessible because the substructure representing the first clause of a two-clause sentence serves as a foundation for the whole sentence-level representation.

‣ Assessment of Competition between Fisheries and Steller Sea Lions in Alaska Based on Estimated Prey Biomass, Fisheries Removals and Predator Foraging Behaviour

Hui, Tabitha C. Y.; Gryba, Rowenna; Gregr, Edward J.; Trites, Andrew W.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 07/05/2015 Português
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A leading hypothesis to explain the dramatic decline of Steller sea lions (Eumetopias jubatus) in western Alaska during the latter part of the 20th century is a change in prey availability due to commercial fisheries. We tested this hypothesis by exploring the relationships between sea lion population trends, fishery catches, and the prey biomass accessible to sea lions around 33 rookeries between 2000 and 2008. We focused on three commercially important species that have dominated the sea lion diet during the population decline: walleye pollock, Pacific cod and Atka mackerel. We estimated available prey biomass by removing fishery catches from predicted prey biomass distributions in the Aleutian Islands, Bering Sea and Gulf of Alaska; and modelled the likelihood of sea lions foraging at different distances from rookeries (accessibility) using satellite telemetry locations of tracked animals. We combined this accessibility model with the prey distributions to estimate the prey biomass accessible to sea lions by rookery. For each rookery, we compared sea lion population change to accessible prey biomass. Of 304 comparisons, we found 3 statistically significant relationships, all suggesting that sea lion populations increased with increasing prey accessibility. Given that the majority of comparisons showed no significant effect...

‣ Direct Differentiation of Adult Ocular Progenitors into Striatal Dopaminergic Neurons

Ahmad, Iqbal; Zhao, Xing; Parameswaran, Sowmya; Destache, Christopher J.; Rodriguez-Sierra, Jorge; Thoreson, Wallace B.; Ahmad, Hiba; Sorrentino, John; Balasubramanian, Sudha
Fonte: Korean Society for Stem Cell Research Publicador: Korean Society for Stem Cell Research
Tipo: Artigo de Revista Científica
Publicado em /05/2015 Português
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Parkinson’s disease, characterized by motor dysfunction due to the loss of nigrostriatal dopaminergic neurons, is one of the most prevalent age-related neurodegenerative disorders. Given there is no current cure, the stem cell approach has emerged as a viable therapeutic option to replace the dopaminergic neurons that are progressively lost to the disease. The success of the approach is likely to depend upon accessible, renewable, immune compatible, and non-tumorigenic sources of neural progenitors from which stable dopaminergic neurons can be generated efficaciously. Here, we demonstrate that neural progenitors derived from limbus, a regenerative and accessible ocular tissue, represent a safe source of dopaminergic neurons. When the limbus-derived neural progenitors were subjected to a well-established protocol of directed differentiation under the influence of Shh and FGF8, they acquired the biochemical and functional phenotype of dopaminergic neurons that included the ability to synthesize dopamine. Their intrastriatal transplantation in the rat model of hemi-Parkinsonism was associated with a reduction in the amphetamine-induced rotation. No tumor formation was observed 6 weeks post-transplantation. Together, these observations posit limbus-derived neural progenitors as an accessible and safe source of dopaminergic neurons for a potential autologous ex-vivo stem cell approach to Parkinson’s disease.

‣ Human Gingival Integration-Free iPSCs; a Source for MSC-Like Cell

Umezaki, Yasuyuki; Hashimoto, Yoshiya; Nishishita, Naoki; Kawamata, Shin; Baba, Shunsuke
Fonte: MDPI Publicador: MDPI
Tipo: Artigo de Revista Científica
Publicado em 15/06/2015 Português
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Mesenchymal stem cells (MSCs) are considered a potential autologous therapy for tissue engineering. The available procedures for MSC retrieval from patients are invasive, and their limited in vitro proliferation restricts their use in the treatment of damaged tissues. Therefore, it is important to establish an alternative and safe source of MSCs. The objective of this study was to demonstrate induced pluripotent stem cell (iPSC) generation from a combination of an accessible source tissue and an integration-free method; we also attempted the differentiation of iPSCs into MSC-like cells (MSLCs) for future autologous tissue engineering. iPSCs were derived from human gingival tissues, which are easily accessible in the field of dentistry, via the use of non-integrating episomal plasmids. Established iPSCs expressed embryonic stem (ES) cell-specific markers, as assessed by gene analysis and immunocytochemistry. Embryoid bodies and teratoma formation were formed from iPSCs, showing their capacity to differentiate into three germ layers. Furthermore, we were successful in differentiating iPSCs into MSLCs. They tested positively for their capacity of trilineage differentiation. Our results demonstrate that human gingival integration-free iPSCs...

‣ Targeting Highly Structured RNA by Cooperative Action of siRNAs and Helper Antisense Oligomers in Living Cells

Dutkiewicz, Mariola; Ojdowska, Agata; Kuczynski, Jakub; Lindig, Vanessa; Zeichhardt, Heinz; Kurreck, Jens; Ciesiołka, Jerzy
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 26/08/2015 Português
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RNA target accessibility is one of the most important factors limiting the efficiency of RNA interference-mediated RNA degradation. However, targeting RNA viruses in their poorly accessible, highly structured regions can be advantageous because these regions are often conserved in sequence and thus less prone to viral escape. We developed an experimental strategy to attack highly structured RNA by means of pairs of specifically designed small interfering RNAs and helper antisense oligonucleotides using the 5’ untranslated region (5’UTR) of coxsackievirus B3 as a model target. In the first step, sites accessible to hybridization of complementary oligonucleotides were identified using two mapping methods with random libraries of short DNA oligomers. Subsequently, the accessibility of the mapped regions for hybridization of longer DNA 16-mers was confirmed by an RNase H assay. Using criteria for the design of efficient small interfering RNAs (siRNA) and a secondary structure model of the viral 5’UTR, several DNA 19-mers were designed against partly double-stranded RNA regions. Target sites for DNA 19-mers were located opposite the sites which had been confirmed as accessible for hybridization. Three pairs of DNA 19-mers and the helper 2’-O-methyl-16-mers were able to effectively induce RNase H cleavage in vitro. For cellular assays...

‣ Exemplars or Beliefs? The Impact of Self-View on the Nature and Relative Influence of Brand Associations

Ng, Sharon; Houston, Michael J.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica Formato: text/html
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This research examines whether various forms of brand associations—overall brand beliefs (e.g., Sony is high quality) versus exemplars of the brand (e.g., Sony TV)—are differentially accessible for individuals with independent self-views and those with an interdependent self-view. Since independents emphasize the “traitedness” of behavior and tend to focus on attributes of objects, brand beliefs are relatively more accessible than exemplars to them. Conversely, since interdependents focus more on the role of contextual factors and the interrelatedness of events, exemplars are relatively more accessible to them than brand beliefs. Further, examination of the implications of this difference on brand attitudes and brand extension evaluations occurs.

‣ Partially-Synchronized DEC-MDPs in Dynamic Mechanism Design

Seuken, Sven; Cavallo, Ruggiero; Parkes, David C.
Fonte: Association for the Advancement of Artificial Intelligence Publicador: Association for the Advancement of Artificial Intelligence
Tipo: Monograph or Book
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In this paper, we combine for the first time the methods of dynamic mechanism design with techniques from decentralized decision making under uncertainty. Consider a multi-agent system with self-interested agents acting in an uncertain environment, each with private actions, states and rewards. There is also a social planner with its own actions, rewards, and states, acting as a coordinator and able to influence the agents via actions (e.g., resource allocations). Agents can only communicate with the center, but may become inaccessible, e.g., when their communication device fails. When accessible to the center, agents can report their local state (and models) and receive recommendations from the center about local policies to follow for the present period and also, should they become inaccessible, until becoming accessible again. Without self-interest, this poses a new problem class which we call partially-synchronized DEC-MDPs, and for which we establish some positive complexity results under reasonable assumptions. Allowing for self-interested agents, we are able to bridge to methods of dynamic mechanism design, aligning incentives so that agents truthfully report local state when accessible and choose to follow the prescribed "emergency policies" of the center.; Engineering and Applied Sciences

‣ Algorithms for Scalable Synchronization on Shared-Memory Multiprocessors

Mellor-Crummey, John M. (1962 - ); Scott, Michael L. (1959 - )
Fonte: University of Rochester. Computer Science Department. Publicador: University of Rochester. Computer Science Department.
Tipo: Relatório
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Busy-wait techniques are heavily used for mutual exclusion and barrier synchronization in shared-memory parallel programs. Unfortunately, typical implementations of busy-waiting tend to produce large amounts of memory and interconnect contention, introducing performance bottlenecks that become markedly more pronounced as applications scale. We argue that this problem is not fundamental, and that one can in fact construct busy-wait synchronization algorithms that induce no memory or interconnect contention. The key to these algorithms is for every processor to spin on separate locally-accessible flag variables, and for some other processor to terminate the spin with a single remote write operation at an appropriate time. Flag variables may be locally-accessible as a result of coherent caching, or by virtue of allocation in the local portion of physically distributed shared memory. We present a new scalable algorithm for spin locks that generates O(1) remote references per lock acquisition, independent of the number of processors attempting to acquire the lock. Our algorithm provides reasonable latency in the absence of contention, requires only a constant amount of space per lock, and requires no hardware support other than a swap-with-memory instruction. We also present a new scalable barrier algorithm that generates O(1) remote references per processor reaching the barrier...

‣ Um processo para o desenvolvimento de aplicações Web acessíveis

Maia, Lucinéia Souza
Fonte: Universidade Federal de Mato Grosso do Sul Publicador: Universidade Federal de Mato Grosso do Sul
Tipo: Dissertação de Mestrado
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A Internet é um importante meio de transmissão de informação, de interação entre pessoas, realização de negócios, educação e serviços governamentais. Porém, problemas de acessibilidade no conteúdo Web têm contribuído para a exclusão de usuários, principalmente aqueles com algum tipo de deficiência. Tal processo de exclusão culmina na problematização sobre Acessibilidade Web, motivando pesquisas por métodos, técnicas e ferramentas específicas para oferecer ao desenvolvedor mecanismos que favoreçam o desenvolvimento de aplicações Web acessíveis. Neste contexto, este trabalho propõe um Modelo de Tarefas de Acessibilidade (MTA) inseridas nos subprocessos do Processo de Desenvolvimento da Norma ISO/IEC 12207 (Padrão para Tecnologia da Informação – Processos do Ciclo de Vida do Software) para auxiliar a análise, projeto, implementação e avaliação de softwares acessíveis. De forma a oferecer uma ferramenta automatizada para auxiliar o desenvolvimento de aplicações Web acessíveis, a ferramenta de autoria Pantaneiro foi adaptada considerando um conjunto de tarefas do MTA e diretrizes do WCAG (Web Content Accessibility Guidelines) 2.0 Nível A. Um estudo de caso foi realizado com grupos de desenvolvedores utilizando o MTA e o Pantaneiro acessível com o objetivo de testar...

‣ Garantia de qualidade em páginas web para dispositivos móveis: acessibilidade e restrições de hardware

Yamakawa, Carlos Américo Perazolo
Fonte: Universidade Federal de Mato Grosso do Sul Publicador: Universidade Federal de Mato Grosso do Sul
Tipo: Dissertação de Mestrado
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Hoje um dos meios de comunicação mais utilizados é a Internet. Assim, é fundamental garantir que seu conteúdo esteja sempre disponível e acessível, a qualquer hora, local, ambiente, dispositivo de acesso e a todos os visitantes/usuários. Há alguns anos o foco principal das pesquisas sobre acessibilidade Web tem sido voltado às pessoas que possuem necessidades especiais, o que continua sendo uma prioridade. Porém, com a popularização da utilização de dispositivos móveis para acessar a Internet, a acessibilidade Web voltada aos usuários desses dispositivos vem ganhando espaço. Com o aumento de usuários de dispositivos móveis, aumentou também a demanda dos usuários de acessar um site que, além de bem atualizado, seja bem apresentável, acessível e leve, levando em consideração os recursos reduzidos destes aparelhos. Porém, a variedade de dispositivos no mercado, com diversas configurações, torna a adaptação de um site ao dispositivo mais complexa. Neste trabalho, é apresentada uma maneira de adaptar dinamicamente um site com base nas configurações do dispositivo que o está acessando. Para isso, foram criadas regras de acessibilidade para dispositivos móveis, que foi incorporado ao Framework Pantaneiro...

‣ Health promotion in schools: a multi-method evaluation of an Australian School Youth Health Nurse Program

Banfield, Michelle; McGorm, Kelly; Sargent, Ginny
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
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BACKGROUND: Health promotion provides a key opportunity to empower young people to make informed choices regarding key health-related behaviours such as tobacco and alcohol use, sexual practices, dietary choices and physical activity. This paper describes the evaluation of a pilot School Youth Health Nurse (SYHN) Program, which aims to integrate a Registered Nurse into school communities to deliver health promotion through group education and individual sessions. METHODS: The evaluation was guided by the RE-AIM (reach, effectiveness, adoption, implementation, maintenance) framework. The objectives were to explore: 1) whether the Program was accessible to the high school students; 2) the impacts of the Program on key stakeholders; 3) which factors affected adoption of the Program; 4) whether implementation was consistent with the Program intent; and 5) the long-term sustainability of the Program. Research included retrospective analysis of Program records, administration of a survey of student experiences and interviews with 38 stakeholders. RESULTS: This evaluation provided evidence that the SYHN Program is reaching students in need...

‣ The performance of DGT versus conventional soil phosphorus tests in tropical soils: an isotope dilution study

Six, L.; Pypers, P.; Degryse, J.; Smolders, E.; Merckx, R.
Fonte: Kluwer Academic Publ Publicador: Kluwer Academic Publ
Tipo: Artigo de Revista Científica
Publicado em //2012 Português
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BACKGROUND AND AIMS: A soil test that samples nutrients only from fractions that are accessible to plants will predict availability and uptake more robustly than empirical tests. This can be tested by comparison of the isotope ratios (specific activity, SA) of the nutrient between plant and the soil extract. This study was set up to assess this requirement for the diffusive gradients in thin films technique (DGT), recently proposed as a soil P test, in comparison with conventional soil P tests viz. Olsen, Colwell, Bray-1, Mehlich-3, ammonium oxalate, anion exchange membranes (AEM) and 0.01M CaCl2 solution. METHODS: Maize (Zea mays L.) was grown in two Pdeficient soils from western Kenya with contrasting P sorption characteristics, amended with a low and a high P rate and labelled with 33P. RESULTS: The SA in the plant shoot corresponded with that of the extracts of the different soil tests, except for CaCl2 and ammonium oxalate extracts, at the low P rate in the soil with low P sorption capacity, Teso soil. For the high P rate on this soil, differences in SA between maize shoot and soil test were small for all established soil tests, but significant for the Colwell, Bray-1, Mehlich-3 and AEM tests. The SA in the soil extracts was significantly smaller than that in the maize shoot for Sega the strongly P-sorbing soil at both P rates for all conventional tests...

‣ Size-exclusion colloidal transport in porous media - stochastic modeling and experimental study

You, Z.; Badalyan, A.; Bedrikovetski, P.
Fonte: Society of Petroleum Engineers Publicador: Society of Petroleum Engineers
Tipo: Artigo de Revista Científica
Publicado em //2012 Português
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Suspension, colloidal, and emulsion flow in rocks with particle size-exclusion may have a strong effect on the reservoir and on the well behavior during fines migration and production, drilling-fluid invasion into oil- or gas-bearing formations, or injection of seawater or produced water. The stochastic microscale equations for size-exclusion colloidal transport in porous media (PM) are derived. The proposed model includes the following new features: It accounts for the accessible flux in the expression for capture rate, it accounts for the increase of inlet concentration caused by the injected particles entering only the accessible area, and it accounts for the dilution of effluent accessible flux in the overall flux of the produced suspension. Two sets of laboratory tests on short-term injection of monosized suspensions have been carried out in engineered PM. The treatment of the laboratory data for short-term continuous-suspension injection shows good agreement with the modeling results. The proposed model shows a better fit to the experimental data than the previous population-balance model for suspension transport in PM, which validates the proposed modified model.; Zhenjiang You, Alexander Badalyan, and Pavel Bedrikovetsky

‣ A STUDY OF CHAR GASIFICATION REACTIONS (COAL CONVERSION, COMBUSTION, CATALYTIC, MODELING, PORE STRUCTURE)

BALLAL, GIRISH DAMODAR
Fonte: Universidade Rice Publicador: Universidade Rice
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Structural, kinetic and catalytic effects relevant to the combustion and gasification of coal-derived chars were investigated. A Texas lignite, an anthracite and two bituminous coals, Pittsburgh #8 and Illinois #6, were pyrolyzed in a nitrogen atmosphere to prepare chars. Optical microscopy, mercury porosimetry and gas adsorption techniques using nitrogen, CO(,2) and CO, were employed for pore structure characterization. The micropores present in the lignite char were accessible to all adsorbents. However, a substantial fraction of the pore space in other chars was inaccessible to nitrogen at 77(DEGREES)K. The lignite char also exhibited the fastest rates of gaseous diffusion, followed in order of decreasing diffusivities by the Illinois #6, Pittsburgh #8 and anthracite chars. The changes in reactivities and pore structures of chars were measured experimentally during their reaction with oxygen (400-550(DEGREES)C) and CO(,2) (800-1000(DEGREES)C). For a particular char-gas system, the normalized rate-conversion pattern was invariant with respect to temperature and gaseous concentration. In the case of lignite and Pittsburgh #8 chars, the rate-conversion pattern was similar during reaction with oxygen and CO(,2). Adsorption experiments on partially reacted chars indicated that the micropores in the lignite char were accessible to both reactants. The micropores in the Illinois #6 char were...

‣ A maritime information exchange model (MIEM) for sharing actionable intelligence

Dwyer, C.; Hayes-Roth, R.; Reading, D.; Small, G.
Fonte: Naval Research Laboratory Publicador: Naval Research Laboratory
Tipo: Artigo de Revista Científica
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The 9/11 Commission Report and related Presidential directives have highlighted the need to share information between different government agencies, military services, and international allies. With sponsorship from the Navy and the Office of the Secretary of Defense (OSD), NRL provided the technical leadership for the Comprehensive Maritime Awareness (CMA) Joint Capabilities Technology Demonstration (JCTD) aimed specifically at developing and demonstrating effective means for sharing maritime intelligence to improve interdiction of suspicious or threatening vessels, cargo, and people. To accomplish sharing in an effective manner, we need to enable humans and computers to understand situational intelligence so that they can respond quickly to significant events. As the number of sensors and interworked systems increase, the data volumes continue to soar, so people will need to rely on the machines to assess and filter more and more of the data. Human attention will need to focus on key events and making important judgments. The Department of Defense (DoD) plans to improve information sharing by making information assets understandable and accessible. We term information understandable when it consists of familiar types and values. We consider it accessible when computerized services can obtain it for us. Thus...