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Residential water demand under block rates: a Portuguese case study

Martins, Rita; Fortunato, Adelino
Fonte: FEUC. Grupo de Estudos Monetários e Financeiros Publicador: FEUC. Grupo de Estudos Monetários e Financeiros
Tipo: Trabalho em Andamento
ENG
Relevância na Pesquisa
35.7%
A residential water demand equation is estimated using a panel data sample of 5 Portuguese local communities and 72 months, corresponding to a total number of 360 observations. Because of the presence of multi-part tariffs, we use as explanatory variables the two common price-related variables: marginal price and difference. To prevent the simultaneity bias from using observed quantities to determine the values of marginal price and difference directly from the rate schedule, we use an instrumental variable approach to create a constant marginal price and difference parameters for each rate structure. The price elasticity value obtained fall within the range of those found in other case studies. Thus, although presenting weak elasticity, price seems to play a role in water demand management. However, we do not confirm the expected influence of difference on residential water demand. This can be a consequence of the complexity of the Portuguese water tariffs and the confusing signs that come from the simultaneous use of fixed quotas and increasing block tariffs. So, it is imperative to clarify water tariffs objectives by reviewing the Portuguese water tariffs design processes.

Estrutura do pasto e taxa de consumo de forragem de amendoim forrageiro (Arachis pintoi Krapovickas & Gregory cv. Belmonte) submetido a intensidades de pastejo; Sward structure and rate of herbage intake in forage peanut (Arachis pintoi Krapovickas & Gregory cv. Belmonte) subjected to intensities of grazing

Silva, Guilherme Portes
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 12/02/2014 PT
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A introdução de leguminosas em pastagens contribui para a produção animal sustentável, proporcionada pela fixação biológica do nitrogênio atmosférico e elevado valor nutritivo da forragem produzida. O conhecimento da estrutura do dossel forrageiro é fundamental para o manejo adequado de sistemas pastoris, uma vez que determina as respostas de plantas e de animais. Estudos com gramíneas tropicais evidenciaram a importância e a praticidade do uso da altura do pasto como guia de manejo eficiente para explicar variações em comportamento ingestivo de animais, permitindo a definição de metas ou alvos de manejo de pasto que maximizam a velocidade de ingestão de forragem. Entretanto, estudos dessa natureza são escassos com leguminosas tropicais. Nesse contexto, o objetivo deste estudo foi avaliar a estrutura do dossel forrageiro e a taxa de consumo de forragem em amendoim forrageiro (Arachis pintoi cv. Belmonte) submetido a intensidades de pastejo. O experimento foi conduzido na Escola Superior de Agricultura "Luiz de Queiroz", Piracicaba, SP, de fevereiro a novembro de 2013. Os tratamentos corresponderam a quatro intensidades de pastejo representadas pelas alturas de 5, 10, 15 e 20 cm, e foram alocados às unidades experimentais (piquetes de 200 m²) segundo delineamento de blocos completos casualizados...

Manejo do milheto em pastoreio rotativo para maximizar a taxa de ingestão por vacas leiteiras; Rotational grazing management in a tropical pasture to maximize the dairy cow’s herbage intake rate

Mezzalira, Jean Carlos; Carvalho, Paulo Cesar de Faccio; Amaral, M.F.; Bremm, Carolina; Trindade, Júlio Kuhn da; Gonçalves, Edna Nunes; Genro, Teresa Cristina Moraes; Silva, R.W.S.M.
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
POR
Relevância na Pesquisa
35.67%
Avaliaram-se os efeitos da estratégia de pastoreio rotacionado sobre a dinâmica do rebaixamento do milheto (Pennisetum glaucum (L.) R. Br.) pastejado por vacas leiteiras. Os tratamentos consistiram de um fatorial entre duas alturas pré-pastejo, 60 e 40cm, e duas pós-pastejo, 20 e 10cm, alocados em um delineamento em blocos ao acaso com quatro repetições. A estrutura do pasto foi avaliada durante o processo de pastejo a cada 10 minutos, por meio de medições de altura. A taxa de rebaixamento da altura do pasto no tratamento 40-20 apresentou-se relativamente constante ao longo de todo o rebaixamento. O tratamento 60-10 apresentou o maior declínio na taxa de rebaixamento. A taxa de rebaixamento no tratamento 40-10 diminuiu em ritmo mais lento em relação à dos tratamentos com 60cm de altura pré-pastejo. As maiores taxas de ingestão foram observadas nos tratamentos de altura pré-pastejo de 60cm, e considerou-se como a melhor estratégia de manejo a combinação 60-20cm de altura do pasto.; This study aimed to evaluate the effects of rotational grazing strategies on the dynamics of the grazing pastures of millet (Pennisetum glaucum (L.) R. Br.) grazed by dairy cows. Treatments consisted of two pre-grazing heights (60 and 40cm) and two post-grazing heights (20 and 10cm) allocated in a randomized block design with four replications. The sward height was evaluated during grazing every 10 minutes. The rate of grazing down of the sward height of the pasture on the 40-20 grazing strategy was relatively constant throughout the grazing down. Treatment 60-10 showed the largest decline in the rate of grazing down. The rate of grazing down in the 40-10 treatment decreased with a slower intensity when compared to the treatments with 60cm of pre-grazing sward height. The major intake rates were observed in treatments with pre-grazing sward height of 60cm. The best management strategy was considered the combination of 60-20cm of sward height.

Human Haplotype Block Sizes Are Negatively Correlated With Recombination Rates

Greenwood, Tiffany A.; Rana, Brinda K.; Schork, Nicholas J.
Fonte: Cold Spring Harbor Laboratory Press Publicador: Cold Spring Harbor Laboratory Press
Tipo: Artigo de Revista Científica
Publicado em /07/2004 EN
Relevância na Pesquisa
35.91%
The International Haplotype Map (“HapMap”) Project is motivated, in part, by the belief that the organization of the human genome, the mechanics of recombination, and the population-level behavior of alleles at adjacent loci should allow researchers to parse the genome into small segments, or “blocks,” that show strong linkage disequilibrium (LD) between alleles at loci within those segments. The discovery and evidence for these blocks is to be based solely on the observed LD strength and patterns between alleles at adjacent loci throughout the genome. Although there are many factors that contribute to LD strength, we assessed the correlation between block structure, in terms of length and percentage of the genome assembled into blocks within a region, and recombination rate obtained from two independent sources. We found evidence of a striking negative correlation between the average recombination rate and average block length, suggesting that recombination rate is a strong contributor to haplotype block structure within the genome. We discuss the potential implications of this negative correlation in the context of the organization, properties, and potential ubiquity of a block-like structure in the human genome.

Scorpion toxin block of the early K+ current (IKf) in rat dorsal root ganglion neurones.

Matteson, D R; Blaustein, M P
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/09/1997 EN
Relevância na Pesquisa
25.82%
1. The ability of three structurally homologous scorpion toxins to block voltage-dependent K+ currents in rat dorsal root ganglion neurones was examined using the patch-clamp technique. 2. Neurones with a diameter > 35 microns had two identifiable components of macroscopic K+ current. The outward current during depolarizations had both inactivating and non-inactivating components, and the tail currents had both a fast component (IKf) with a time constant of about 2.5 ms and a slow component (IKs) with a time constant of about 10 ms. 3. The functional properties of IKf and IKs differed in several ways: (i) IKf activated over a more negative voltage range than IKs; (ii) IKf partially inactivated during a depolarization to +70 mV, whereas IKs did not inactivate during a 1 s depolarization to +70 mV; (iii) IKf activated more rapidly than IKs; and (iv) alpha-dendrotoxin selectively blocked IKf. 4. Tityustoxin-K alpha (TsTX-K alpha) selectively blocked IKf, with little or no effect on IKs. The block was concentration dependent, with 50% of the current inhibited at a toxin concentration of about 38 nM. 5. TsTX-K alpha block of IKf was completely reversible, but the washout rate was slow. The time constant of recovery from TsTX-K alpha block was about 11 min. 6. Charybdotoxin (CTX) also selectively blocked IKf in a reversible manner...

Dual actions of procainamide on batrachotoxin-activated sodium channels: open channel block and prevention of inactivation.

Zamponi, G W; Sui, X; Codding, P W; French, R J
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1993 EN
Relevância na Pesquisa
25.83%
We have investigated the action of procainamide on batrachotoxin (BTX)-activated sodium channels from bovine heart and rat skeletal muscle. When applied to the intracellular side, procainamide induced rapid, open-channel block. We estimated rate constants using amplitude distribution analysis (Yellen, G. 1984. J. Gen. Physiol. 84:157). Membrane depolarization increased the blocking rate and slowed unblock. The rate constants were similar in both magnitude and voltage dependence for cardiac and skeletal muscle channels. Qualitatively, this block resembled the fast open-channel block by lidocaine (Zamponi, G. W., D. D. Doyle, and R. J. French. 1993. Biophys. J. 65:80), but procainamide was about sevenfold less potent. Molecular modeling suggests that the difference in potency between procainamide and lidocaine might arise from the relative orientation of their aromatic rings, or from differences in the structure of the aryl-amine link. For the cardiac channels, procainamide reduced the frequency of transitions to a long-lived closed state which shows features characteristic of inactivation (Zamponi, G. W., D. D. Doyle, and R. J. French. 1993. Biophys J. 65:91). Mean durations of kinetically identified closed states were not affected. The degree of fast block and of inhibition of the slow closures were correlated. Internally applied QX-314...

Multiple intermediate states precede pore block during N-type inactivation of a voltage-gated potassium channel

Prince-Carter, Alison; Pfaffinger, Paul J.
Fonte: The Rockefeller University Press Publicador: The Rockefeller University Press
Tipo: Artigo de Revista Científica
Publicado em /07/2009 EN
Relevância na Pesquisa
25.83%
N-type inactivation of voltage-gated potassium channels is an autoinhibitory process that occurs when the N terminus binds within the channel pore and blocks conduction. N-type inactivation and recovery occur with single-exponential kinetics, consistent with a single-step reaction where binding and block occur simultaneously. However, recent structure–function studies have suggested the presence of a preinactivated state whose formation and loss regulate inactivation and recovery kinetics. Our studies on N-type inactivation of the Shaker-type AKv1 channel support a multiple-step inactivation process involving a series of conformational changes in distinct regions of the N terminus that we have named the polar, flex, and latch regions. The highly charged polar region forms interactions with the surface of the channel leading up to the side window openings between the T1 domain and the channel transmembrane domains, before the rate-limiting step occurs. This binding culminates with a specific electrostatic interaction between R18 and EDE161-163 located at the entrance to the side windows. The latch region appears to work together with the flex region to block the pore after polar region binding occurs. Analysis of tail currents for a latch region mutant shows that both blocked and unblocked states exist after the rate-limiting transition is passed. Our results suggest that at least two intermediate states exist for N-type inactivation: a polar region–bound state that is formed before the rate-limiting step...

Nanostructure of Solid Precipitates Obtained by Expansion of Polystyrene-block-Polybutadiene Solutions in Near Critical Propane: Block Ratio and Micellar Solution Effects

Green, Jade; Tyrrell, Zachary; Radosz, Maciej; Hong, Kunlun; Mays, Jimmy W.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 19/05/2011 EN
Relevância na Pesquisa
25.89%
In contrast to incompressible liquid solutions, compressible near-critical solutions of block copolymers allow for controlling rapid structure transformations with pressure alone. For example, when dissolved in near-critical propane, polystyrene-block-polybutadiene can form a random molecular solution at high pressures, a micellar solution at moderate pressures, and a solvent-free precipitate at low pressures. In contrast to the unstructured virgin copolymer, such a propane-treated precipitate rapidly self assembles toward structures characteristic of equilibrated block copolymers, such as lamellae, spheres or cylinders, which depend on the block ratio rather than on the decompression rate or temperature, at least within the rate and temperature ranges investigated in this work. At lower temperatures, however, say below 40 °C, glass transition of the styrene-butadiene diblocks can inhibit independent structure formation while crystallization of their hydrogenated-butadiene analogs can preserve the micellar-solution structure.

Amphiphilic linear-dendritic block copolymers for drug delivery

Nguyen, Phuong, Ph. D. Massachusetts Institute of Technology
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 250 p.
ENG
Relevância na Pesquisa
25.81%
Polymeric drug delivery systems have been widely used in the pharmaceutical industry. Such systems can solubilize and sequester hydrophobic drugs from degradation, thereby increasing circulation half-life and efficacy. However, there are still challenges in the design of drug delivery vehicles to achieve efficient drug delivery in a site-specific manner. In this thesis, an amphiphilic linear-dendritic block copolymer was designed, synthesized, and applied as a new polymeric drug delivery platform. First, to develop the drug delivery vehicle, an ABA dendritic-linear-dendritic block copolymer consisting of poly(amidoamine) (PAMAM) and poly(propylene oxide) (PPO) was synthesized. In order to determine the viability of the linear-dendritic block copolymer as a drug delivery vehicle, the solution-phase self-assembly behavior and the self-assembled structures were characterized experimentally and through molecular dynamics simulations. The triblock self-assembles in aqueous media to form stable micelles with low CMC values. Dynamic light scattering results and TEM indicate the formation of particles ranging from 9 to 18 nm in diameter, with smaller diameters exhibited at higher generations. Static light scattering also confirmed the trend where the aggregation number decreased with higher generations. The experimental characterization results indicated that the physical characteristics of the PPO-PAMAM micelles were desirable and within the design specifications necessary for drug delivery. The experimental results were utilized to set up simulations where further knowledge of the microstructure of the micelles formed could be gained. It was found that the block copolymers simulated formed micelles in the same size range that was seen experimentally. However...

Estrutura do dossel, interceptação de luz e massa de forragem em capim-marandu submetido a estratégias de pastejo intermitente e adubação nitrogenada; Sward structure, light interception and forage mass of marandu palisadegrass subjected to strategies of intermittent stocking and nitrogen fertilisation

GOMES, Marcelo Barcelo
Fonte: Universidade Federal de Goiás; BR; UFG; Mestrado em Agronomia - Regional Jataí; Ciências Agrárias Publicador: Universidade Federal de Goiás; BR; UFG; Mestrado em Agronomia - Regional Jataí; Ciências Agrárias
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
25.85%
The objective of this experiment was to evaluate combinations of two intermittent grazing intervals that corresponding to the time required for the sward reached 25 and 35 cm heights and two nitrogen application doses (50 and 200 kg N/ha/year) on the sward structure, light interception and forage production of Marandugrass pastures. The experiment was conducted at IZ - Institute of Animal Science, located in Nova Odessa, SP. Treatments which were denominated like their heights and dose relations by 25/50, 25/200, 35/50 and 35/200 were allocated at experimental units constituting sets of six paddocks of 0.5 ha each in a 2 x 2 (two heights and two doses) factorial arrangement in randomized complete block design, with four replications, totaling an area of 48 ha. The variables were the number of cycle grazing, grazing days, rest days, light interception, leaf area, foliage angle, herbage dry matter (DM), leaf:stem ratio, morphological components spatial distribution along the grass vertical profile, bulk density, total herbage and morphological components and herbage accumulation rate. The data were analyzed in split split plot in a mixed model, considering random and block errors effects. In the plot were considered the time effect (summer I from December 2009 to January 2010 and summer II from February to March 2010) and the block...

The Impacts of Metering and Climate Conditions on Residential Electricity Demand : The Case of Albania

Iimi, Atsushi
Fonte: Banco Mundial Publicador: Banco Mundial
Relevância na Pesquisa
35.7%
Albania is among the most vulnerable countries to external energy shocks and climatic conditions, because of its high dependency on hydropower for electricity. Given highly volatile international energy prices and expected global warming, it is becoming increasingly important to manage the demand for electricity. However, the country has long been faced with a significant problem of electricity metering. About one-third of total energy is lost for technical and nontechnical reasons. This paper estimates the residential demand function by applying a two-stage system equation method for an endogenous censored variable, because the lack of metering makes the electricity consumption partially observable for the econometrician. It is found that metering is important to curb non-essential electricity use by households. The electricity demand could also be reduced by raising the first block rate and lowering the second block rate and the threshold between the two blocks. In addition, weather conditions and home appliance ownership would affect the demand for electricity. But the latter looks more influential than the former.

Cost Recovery, Equity, and Efficiency in Water Tariffs : Evidence from African Utilities

Banerjee, Sudeshna; Foster, Vivien; Ying, Yvonne; Skilling, Heather; Wodon, Quentin
Fonte: Banco Mundial Publicador: Banco Mundial
Relevância na Pesquisa
35.89%
Water and sanitation utilities in Africa operate in a high-cost environment. They also have a mandate to at least partially recover their costs of operations and maintenance (O&M). As a result, water tariffs are higher than in other regions of the world. The increasing block tariff (IBT) is the most common tariff structure in Africa. Most African utilities are able to achieve O&M cost recovery at the highest block tariffs, but not at the first-block tariffs, which are designed to provide affordable water to low-volume consumers, who are often poor. At the same time, few utilities can recover even a small part of their capital costs, even in the highest tariff blocks. Unfortunately, the equity objectives of the IBT structure are not met in many countries. The subsidy to the lowest tariff-block does not benefit the poor exclusively, and the minimum consumption charge is often burdensome for the poorest customers. Many poor households cannot even afford a connection to the piped water network. This can be a significant barrier to expansion for utilities. Therefore...

Water Markets, Demand and Cost Recovery for Piped Water Supply Services : Evidence from Southwest Sri Lanka

Nauges, Celine; van den Berg, Caroline
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Relevância na Pesquisa
35.8%
In many countries water supply is a service that is seriously underpriced, especially for residential consumers. This has led to a call for setting cost recovery policies to ensure that the tariffs charged for water supply cover the full cost of providing for the service. Yet, the question arises on how consumers will react to such price increases. The authors illustrate the impact of price increases on consumption of piped water through a study of the demand for water of piped and non-piped households using cross-sectional data from 1,800 households in Southwest Sri Lanka. The (marginal) price elasticity is estimated at -0.74 for households exclusively relying on piped water, and at -0.69 for households using piped water but supplementing their supply with other water sources, with no significant differences between income groups. Those households that depend on non-piped water sources have a time cost elasticity (as a proxy for price elasticity) of only -0.06. The authors discuss the implications of these results in terms of pricing policy.

Republic of Armenia : Power Sector Tariff Study

Kochnakyan, Artur; Balabanyan, Ani; Antmann, Pedro; Laderchi, Caterina Ruggeri; Olivier, Anne; Pierce, Lauren; Hankinson, Denzel
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Economic & Sector Work :: Energy Study; Economic & Sector Work
ENGLISH; EN_US
Relevância na Pesquisa
25.83%
Armenia's energy sector has achieved a level of electricity reliability, service quality and efficiency of sector operations that stands out among countries participating in Commonwealth of Independent States (CIS). Much of this can be attributed to a decade of regulatory reform including a long-standing commitment to cost-recovery tariffs. The study is structured as follows: section one provides definitions of the key terms used and a background on the current tariff setting process in Armenia. Section two indicates how far tariffs have departed from cost-recovery levels and what costs have not been covered as a result. Section three describes how new investments will affect the average cost of service and the average residential tariff. Section four proposes a marginal cost-based tariff structure and explains why this differs from the current tariff structure. Section five discusses the poverty and social impact of tariff increases needed to cover new investments in 2021. Section six identifies options for subsidization and mitigating rate shock that will help transition to higher...

The Duality of Spiral Structure, and a Quantitative Dust Penetrated Morphological Tuning Fork at Low and High Redshift

Block, D. L.; Puerari, I.; Buta, R. J.; Abraham, R.; Takamiya, M.; Stockton, A.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 15/01/2001
Relevância na Pesquisa
35.55%
In the near-infrared, the morphology of older star-dominated disks indicates a simple classification scheme (1) H$m$ where $m$ is the dominant harmonic, (2) a pitch angle (derived from the Fourier spectra) associated with the rate of shear A/$\omega$ in the stellar disk and (3) a `bar strength' parameter, robustly derived from the gravitational potential or torque of the bar. A spiral galaxy may present two radically different morphologies in the optical and near-infrared regime; there is no correlation between our quantitative dust penetrated tuning fork and that of Hubble. Applications of our $z\sim$0 Fourier template to the HDF are discussed using $L$ and $M$ band simulations from an 8-m NGST; the rest-wavelength IR morphology of high-$z$ galaxies should probably be a key factor in deciding the final choice of instruments for the NGST.; Comment: 8 pages, 5 figures. To appear in ASP Conf. Ser. "Galaxy Disk and Disk Galaxies", Eds. J.G. Funes S.J. and E.M. Corsini (meeting held in Rome, June 12-16, 2000)

Block-Orthogonal Space-Time Code Structure and Its Impact on QRDM Decoding Complexity Reduction

Ren, Tian Peng; Guan, Yong Liang; Yuen, Chau; Zhang, Er Yang
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
25.83%
Full-rate space time codes (STC) with rate = number of transmit antennas have high multiplexing gain, but high decoding complexity even when decoded using reduced-complexity decoders such as sphere or QRDM decoders. In this paper, we introduce a new code property of STC called block-orthogonal property, which can be exploited by QR-decomposition-based decoders to achieve significant decoding complexity reduction without performance loss. We show that such complexity reduction principle can benefit the existing algebraic codes such as Perfect and DjABBA codes due to their inherent (but previously undiscovered) block-orthogonal property. In addition, we construct and optimize new full-rate BOSTC (Block-Orthogonal STC) that further maximize the QRDM complexity reduction potential. Simulation results of bit error rate (BER) performance against decoding complexity show that the new BOSTC outperforms all previously known codes as long as the QRDM decoder operates in reduced-complexity mode, and the code exhibits a desirable complexity saturation property.; Comment: IEEE Journal of Selected Topics in Signal Processing, Vol. 5, No. 8, December 2011

Construction of Block Orthogonal STBCs and Reducing Their Sphere Decoding Complexity

Jithamithra, G. R.; Rajan, B. Sundar
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
35.86%
Construction of high rate Space Time Block Codes (STBCs) with low decoding complexity has been studied widely using techniques such as sphere decoding and non Maximum-Likelihood (ML) decoders such as the QR decomposition decoder with M paths (QRDM decoder). Recently Ren et al., presented a new class of STBCs known as the block orthogonal STBCs (BOSTBCs), which could be exploited by the QRDM decoders to achieve significant decoding complexity reduction without performance loss. The block orthogonal property of the codes constructed was however only shown via simulations. In this paper, we give analytical proofs for the block orthogonal structure of various existing codes in literature including the codes constructed in the paper by Ren et al. We show that codes formed as the sum of Clifford Unitary Weight Designs (CUWDs) or Coordinate Interleaved Orthogonal Designs (CIODs) exhibit block orthogonal structure. We also provide new construction of block orthogonal codes from Cyclic Division Algebras (CDAs) and Crossed-Product Algebras (CPAs). In addition, we show how the block orthogonal property of the STBCs can be exploited to reduce the decoding complexity of a sphere decoder using a depth first search approach. Simulation results of the decoding complexity show a 30% reduction in the number of floating point operations (FLOPS) of BOSTBCs as compared to STBCs without the block orthogonal structure.; Comment: 16 pages...

The Link Between Rotation Curve Type and Spiral Arm Structure in Disk Galaxies

Seigar, M. S.; James, P. A.; Puerari, I.; Block, D. L.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 09/05/2002
Relevância na Pesquisa
35.55%
Over the last decade it has become clear that there is a decoupling between the old stellar disk and young stellar disk in spiral galaxies. This has led to a scheme for classifying galaxies on the basis of their near-infrared morphology. The near-infrared provides a more physical framework for classifying galaxies as it is both relatively free from extinction and it traces the old stellar population, i.e. the dominant stellar mass distribution. The `dust penetrated class' is dependent upon the spiral pitch angle of arms. We have observed 8 galaxies with UFTI on UKIRT in the K-band in order to investigate the theoretical link between disk dynamics and arm morphology, which is suggested both from numerical models and the dust penetrated class. We find that the pitch angle of spiral arms, i, correlates well with the shear rate of rotation curves, $A/\omega$ (where A is the first Oort constant and $\omega$ is the rotational velocity), over the same radial range.; Comment: To be published in the proceedings 'Galaxy evolution: theory and observations', Eds. V. Avila-Reese, C. Firmani, C. Frenk, & C. Allen, RevMexAA SC (2002)

The Roles of Realistic Cardiac Structure in Conduction and Conduction Block: Studies of Novel Micropatterned Cardiac Cell Cultures

Badie, Nima
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2010
Relevância na Pesquisa
35.97%

The role of cardiac tissue structure in both normal and abnormal impulse conduction has been extensively studied by researchers in cardiac electrophysiology. However, much is left unknown on how specific micro- and macroscopic structural features affect conduction and conduction block. Progress in this field is constrained by the inability to simultaneously assess intramural cardiac structure and function, as well as the intrinsic complexity and variability of intact tissue preparations. Cultured monolayers of cardiac cells, on the other hand, present a well-controlled in vitro model system that provides the necessary structural and functional simplifications to enable well-defined studies of electrical phenomena. In this thesis, I developed a novel, reproducible cell culture system that accurately replicates the realistic microstructure of cardiac tissues. This system was then applied to systematically explore the influence of natural structure (e.g. tissue boundaries, expansions, local fiber directions) on normal and arrhythmogenic electrical conduction.

Specifically, soft lithography techniques were used to design cell cultures based on microscopic DTMRI (diffusion tensor magnetic resonance imaging) measurements of fiber directions in murine ventricles. Protein micropatterns comprised of mosaics of square pixels with angled lines that followed in-plane cardiac fiber directions were created to control the adhesion and alignment of cardiac cells on a two-dimensional substrate. The high accuracy of cell alignment in the resulting micropatterned monolayers relative to the original DTMRI-measured fiber directions was validated using immunofluorescence and image processing techniques.

Using this novel model system...

Block-based transceivers for frequency selective channels with reduced redundancy

Rey Vega,L.; Galarza,C.G.
Fonte: Latin American applied research Publicador: Latin American applied research
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2009 EN
Relevância na Pesquisa
35.69%
We propose a transceiver structure for a frequency selective channel that allows the introduction of reduced redundancy. We optimize jointly the transmitter and receiver in this structure to maximize the information rate. The simulation results show that the proposed design has good performance while increasing the bandwidth efficiency.