854 resultados para Detached Utterances
Resumo:
In several chemical and space industries, small bubbles are desired for efficient interaction between the liquid and gas phases. In the present study, we show that non-uniform electric field with appropriate electrode configurations can reduce the volume of the bubbles forming at submerged needles by up to three orders of magnitude. We show that localized high electric stresses at the base of the bubbles result in slipping of the contact line on the inner surface of the needle and subsequent bubble formation occurs with contact line inside the needle. We also show that for bubble formation in the presence of highly non-uniform electric field, due to high detachment frequency, the bubbles go through multiple coalescences and thus increase the apparent volume of the detached bubbles. (C) 2013 AIP Publishing LLC.
Resumo:
An implementable nonlinear control design approach is presented for a supersonic air-breathing ramjet engine. The primary objective is to ensure that the thrust generated by the engine tracks the commanded thrust without violating the operational constraints. An important constraint is to manage the shock wave location in the intake so that it neither gets detached nor gets too much inside the intake. Both the objectives are achieved by regulating the fuel flow to the combustion chamber and by varying the throat area of the nozzle simultaneously. The design approach accounts for the nonlinear cross-coupling effects and nullifies those. Also, an extended Kalman filter has been used to filter out the sensor and process noises as well as to make the states available for feedback. Furthermore, independent control design has been carried out for the actuators. To test the performance of the engine for a realistic flight trajectory, a representative trajectory is generated through a trajectory optimization process, which is augmented with a newly-developed finite-time state dependent Riccati equation technique for nullifying the perturbations online. Satisfactory overall performance has been obtained during both climb and cruise phases. (C) 2015 Elsevier Masson SAS. All rights reserved.
Resumo:
Resumen: Cuando los medios se refieren a los candidatos políticos en una situación de campaña electoral proyectan una cierta imagen de los mismos a partir de las verbalizaciones que preponderan en los mensajes informativos. El presente trabajo analiza estas verbalizaciones de los medios en el marco de la teoría de la Agenda Setting, más específicamente en el segundo nivel de esta teoría, la cual hace referencia a los atributos o aspectos que caracterizan a los protagonistas de las noticias, para este estudio en particular, los políticos. Esta teoría fue puesta a prueba repetidamente desde su aplicación en las elecciones estadounidenses de 1968 de la mano de sus autores Maxwell McCombs y Donald Shaw. La misma se ha extendido con paso firme desde su país de origen hacia otras latitudes. El objetivo general es describir la imagen de los candidatos presidenciales a partir de las expresiones que preponderan en los medios masivos de comunicación, durante la campaña presidencial en Argentina ocurrida en octubre de 2011. El procedimiento consiste en el relevamiento realizado durante los meses anteriores a las elecciones presidenciales. Para ello fue necesario armar un corpus compuesto por la selección de los medios masivos de comunicación a analizar. Seguidamente se realiza el análisis de contenido del corpus y se procede al análisis de los datos, de ello deriva una base de datos, donde la unidad de análisis fue la mención de los diversos aspectos o características de los candidatos políticos. Los aspectos o características fueron tomados de investigaciones anteriores que aplicaron la misma metodología y que fueron realizadas en nuestro país también en situaciones de contextos electorales. Por ello es factible de efectuar comparaciones en el tiempo, ya que una de las enormes riquezas de la teoría de la Agenda Setting es la de ser susceptible de comparación por tratarse de una metodología de análisis sistemático. La revisión de la teoría de la Agenda Setting que enmarca esta investigación pretende introducirnos primeramente en las investigaciones de medios masivos en general para luego focalizar en la teoría propiamente dicha y más aún en el segundo nivel de la teoría que trata de los atributos de los personajes públicos Se realiza posteriormente una breve sinopsis de investigaciones en Latinoamérica y Argentina, sobre temas relacionados con campañas electorales y no electorales para finalmente de manera concatenada dar cuenta de trabajos realizados en nuestro país en situaciones de campañas políticas
Resumo:
The controlled equations defined in a physical plane are changed into those in a computational plane with coordinate transformations suitable for different Mach number M(infinity). The computational area is limited in the body surface and in the vicinities of detached shock wave and sonic line. Thus the area can be greatly cut down when the shock wave moves away from the body surface as M(infinity) --> 1. Highly accurate, total variation diminishing (TVD) finite-difference schemes are used to calculate the low supersonic flowfield around a sphere. The stand-off distance, location of sonic line, etc. are well comparable with experimental data. The long pending problem concerning a flow passing a sphere at 1.3 greater-than-or-equal-to M(infinity) > 1 has been settled, and some new results on M(infinity) = 1.05 have been presented.
Resumo:
[ES]En este trabajo se estudia el uso de los marcadores del discurso y del asíndeton como medios de articulación textual entre los diversos enunciados que constituyen los "Progumnásmata" de Nicolao. Este estudio permite observar si existen diferencias entre las dos partes que componen la edición de Felten y si el uso de partículas de Nicolao es diferente del que hacen los demás autores de "Progumnásmata".
Resumo:
Functional Electrical Stimulation (FES) is a technique that consists on applying electrical current pulses to artificially activate motor nerve fibers and produce muscle contractions to achieve functional movements. The main applications of FES are within the rehabilitation field, in which this technique is used to aid recovery or to restore lost motor functions. People that benefit of FES are usually patients with neurological disorders which result in motor dysfunctions; most common patients include stroke and spinal cord injury (SCI). Neuroprosthesis are devices that have their basis in FES technique, and their aim is to bridge interrupted or damaged neural paths between the brain and upper or lower limbs. One of the aims of neuroprosthesis is to artificially generate muscle contractions that produce functional movements, and therefore, assist impaired people by making them able to perform activities of daily living (ADL). FES applies current pulses and stimulates nerve fibers by means of electrodes, which can be either implanted or surface electrodes. Both of them have advantages and disadvantages. Implanted electrodes need open surgery to place them next to the nerve root, so these electrodes carry many disadvantages that are produced by the use of invasive techniques. In return, as the electrodes are attached to the nerve, they make it easier to achieve selective functional movements. On the contrary, surface electrodes are not invasive and are easily attached or detached on the skin. Main disadvantages of surface electrodes are the difficulty of selectively stimulating nerve fibers and uncomfortable feeling perceived by users due to sensory nerves located in the skin. Electrical stimulation surface electrode technology has improved significantly through the years and recently, multi-field electrodes have been suggested. This multi-field or matrix electrode approach brings many advantages to FES; among them it is the possibility of easily applying different stimulation methods and techniques. The main goal of this thesis is therefore, to test two stimulation methods, which are asynchronous and synchronous stimulation, in the upper limb with multi-field electrodes. To this end, a purpose-built wrist torque measuring system and a graphic user interface were developed to measure wrist torque produced with each of the methods and to efficiently carry out the experiments. Then, both methods were tested on 15 healthy subjects and sensitivity results were analyzed for different cases. Results show that there are significant differences between methods regarding sensation in some cases, which can affect effectiveness or success of FES.
Resumo:
[EN] One universal feature of human languages is the division between grammatical functors and content words. From a learnability point of view, functors might provide entry points or anchors into the syntactic structure of utterances due to their high frequency. Despite its potentially universal scope, this hypothesis has not yet been tested on typologically different languages and on populations of different ages. Here we report a corpus study and an artificial grammar learning experiment testing the anchoring hypothesis in Basque, Japanese, French, and Italian adults. We show that adults are sensitive to the distribution of functors in their native language and use them when learning new linguistic material. However, compared to infants’ performance on a similar task, adults exhibit a slightly different behavior, matching the frequency distributions of their native language more closely than infants do. This finding bears on the issue of the continuity of language learning mechanism.
Resumo:
[ES] Se trata de una estancia de 35 x 9 metros de planta que se organiza con un banco corrido en tres de sus lados con un respaldo a modo de friso y una serie de mesas de madera, cuenta además con varias ventanas y tres lámparas que aportan la iluminación, una puerta de acceso destacada en madera con cancel, púlpito para la lectura y varios cuadros.
Resumo:
The geology and structure of two crustal scale shear zones were studied to understand the partitioning of strain within intracontinental orogenic belts. Movement histories and regional tectonic implications are deduced from observational data. The two widely separated study areas bear the imprint of intense Late Mesozoic through Middle Cenozoic tectonic activity. A regional transition from Late Cretaceous-Early Tertiary plutonism, metamorphism, and shortening strain to Middle Tertiary extension and magmatism is preserved in each area, with contrasting environments and mechanisms. Compressional phases of this tectonic history are better displayed in the Rand Mountains, whereas younger extensional structures dominate rock fabrics in the Magdalena area.
In the northwestern Mojave desert, the Rand Thrust Complex reveals a stack of four distinctive tectonic plates offset along the Garlock Fault. The lowermost plate, Rand Schist, is composed of greenschist facies metagraywacke, metachert, and metabasalt. Rand Schist is structurally overlain by Johannesburg Gneiss (= garnet-amphibolite grade orthogneisses, marbles and quartzites), which in turn is overlain by a Late Cretaceous hornblende-biotite granodiorite. Biotite granite forms the fourth and highest plate. Initial assembly of the tectonic stack involved a Late Cretaceous? south or southwest vergent overthrusting event in which Johannesburg Gneiss was imbricated and attenuated between Rand Schist and hornblende-biotite granodiorite. Thrusting postdated metamorphism and deformation of the lower two plates in separate environments. A post-kinematic stock, the Late Cretaceous Randsburg Granodiorite, intrudes deep levels of the complex and contains xenoliths of both Rand Schist and mylonitized Johannesburg? gneiss. Minimum shortening implied by the map patterns is 20 kilometers.
Some low angle faults of the Rand Thrust Complex formed or were reactivated between Late Cretaceous and Early Miocene time. South-southwest directed mylonites derived from Johannesburg Gneiss are commonly overprinted by less penetrative north-northeast vergent structures. Available kinematic information at shallower structural levels indicates that late disturbance(s) culminated in northward transport of the uppermost plate. Persistence of brittle fabrics along certain structural horizons suggests a possible association of late movement(s) with regionally known detachment faults. The four plates were juxtaposed and significant intraplate movements had ceased prior to Early Miocene emplacement of rhyolite porphyry dikes.
In the Magdalena region of north central Sonora, components of a pre-Middle Cretaceous stratigraphy are used as strain markers in tracking the evolution of a long lived orogenic belt. Important elements of the tectonic history include: (1) Compression during the Late Cretaceous and Early Tertiary, accompanied by plutonism, metamorphism, and ductile strain at depth, and thrust driven? syntectonic sedimentation at the surface. (2) Middle Tertiary transition to crustal extension, initially recorded by intrusion of leucogranites, inflation of the previously shortened middle and upper crustal section, and surface volcanism. (3) Gravity induced development of a normal sense ductile shear zone at mid crustal levels, with eventual detachment and southwestward displacement of the upper crustal stratigraphy by Early Miocene time.
Elucidation of the metamorphic core complex evolution just described was facilitated by fortuitous preservation of a unique assemblage of rocks and structures. The "type" stratigraphy utilized for regional correlation and strain analysis includes a Jurassic volcanic arc assemblage overlain by an Upper Jurassic-Lower Cretaceous quartz pebble conglomerate, in turn overlain by marine strata with fossiliferous Aptian-Albian limestones. The Jurassic strata, comprised of (a) rhyolite porphyries interstratified with quartz arenites, (b) rhyolite cobble conglomerate, and (c) intrusive granite porphyries, are known to rest on Precambrian basement north and east of the study area. The quartz pebble conglomerate is correlated with the Glance Conglomerate of southeastern Arizona and northeastern Sonora. The marine sequence represents part of an isolated arm? of the Bisbee Basin.
Crosscutting structural relationships between the pre-Middle Cretaceous supracrustal section, younger plutons, and deformational fabrics allow the tectonic sequence to be determined. Earliest phases of a Late Cretaceous-Early Tertiary orogeny are marked by emplacement of the 78 ± 3 Ma Guacomea Granodiorite (U/Pb zircon, Anderson et al., 1980) as a sill into deep levels of the layered Jurassic series. Subsequent regional metamorphism and ductile strain is recorded by a penetrative schistosity and lineation, and east-west trending folds. These fabrics are intruded by post-kinematic Early Tertiary? two mica granites. At shallower crustal levels, the orogeny is represented by north directed thrust faulting, formation of a large intermontane basin, and development of a pronounced unconformity. A second important phase of ductile strain followed Middle Tertiary? emplacement of leucogranites as sills and northwest trending dikes into intermediate levels of the deformed section (surficial volcanism was also active during this transitional period to regional extension). Gravitational instabilities resulting from crustal swelling via intrusion and thermal expansion led to development of a ductile shear zone within the stratigraphic horizon occupied by a laterally extensive leucogranite sill. With continued extension, upper crustal brittle normal faults (detachment faults) enhanced the uplift and tectonic denudation of this mylonite zone, ultimately resulting in southwestward displacement of the upper crustal stratigraphy.
Strains associated with the two ductile deformation events have been successfully partitioned through a multifaceted analysis. R_f/Ø measurements on various markers from the "type" stratigraphy allow a gradient representing cumulative strain since Middle Cretaceous time to be determined. From this gradient, noncoaxial strains accrued since emplacement of the leucogranites may be removed. Irrotational components of the postleucogranite strain are measured from quartz grain shapes in deformed granites; rotational components (shear strains) are determined from S-C fabrics and from restoration of rotated dike and vein networks. Structural observations and strain data are compatable with a deformation path of: (1) coaxial strain (pure shear?), followed by (2) injection of leucogranites as dikes (perpendicular to the minimum principle stress) and sills (parallel to the minimum principle stress), then (3) southwest directed simple shear. Modeling the late strain gradient as a simple shear zone permits a minimum displacement of 10 kilometers on the Magdalena mylonite zone/detachment fault system. Removal of the Middle Tertiary noncoaxial strains yields a residual (or pre-existing) strain gradient representative of the Late Cretaceous-Early Tertiary deformation. Several partially destrained cross sections, restored to the time of leucogranite emplacement, illustrate the idea that the upper plate of the core complex bas been detached from a region of significant topographic relief. 50% to 100% bulk extension across a 50 kilometer wide corridor is demonstrated.
Late Cenozoic tectonics of the Magdalena region are dominated by Basin and Range style faulting. Northeast and north-northwest trending high angle normal faults have interacted to extend the crust in an east-west direction. Net extension for this period is minor (10% to 15%) in comparison to the Middle Tertiary detachment related extensional episode.
Resumo:
Evidence for the stereochemical isomerization of a variety of ansa metallocene compounds is presented. For the scandocene allyl derivatives described here, we have established that the process is promoted by a variety of salts in both ether and hydrocarbon solvents and is not accelerated by light. A plausible mechanism based on an earlier proposal by Marks, et al., is offered as an explanation of this process. It involves coordination of anions and/or donor solvents to the metal center with cation assistance to encourage metalcyclopentadienyl bond heterolysis, rotation about the Si-Cp bond of the detached cyclopentadienide and recoordination of the opposite face. Our observations in some cases of thermodynamic racemic:meso ratios under the reaction conditions commonly used for the synthesis of the metallocene chlorides suggests that the interchange is faster than metallation, such that the composition of the reaction mixture is determined by thermodynamic, not kinetic, control in these cases.
Two new ansa-scandocene alkenyl compounds react with olefins resulting in the formation of η3-allyl complexes. Kinetics and labeling experiments indicate a tuck-in intermediate on the reaction pathway; in this intermediate the metal is bound to the carbon adjacent to the silyllinker in the rear of the metallocene wedge. In contrast, reaction of permethylscandocene alkenyl compounds with olefins results, almost exclusively, in vinylic C-H bond activation. It is proposed that relieving transition state steric interactions between the cyclopentadienyl rings and the olefin by either linking the rings together or using a larger lanthanide metal may allow for olefin coordination, stabilizing the transition state for allylic σ-bond metathesis.
A selectively isotopically labeled propylene, CH2CD(13CH3), was synthesized and its polymerization was carried out at low concentration in toluene solution using isospecific metallocene catalysts. Analysis of the NMR spectra (13C, 1H, and 2H) of the resultant polymers revealed that the production of stereoerrors through chain epimerization proceeds exclusively by the tertiaryalkyl mechanism. Additionally, enantiofacial inversion of the terminally unsaturated polymer chain occurs by a non-dissociative process. The implications of these results on the mechanism of olefin polymerization with these catalysts is discussed.
Resumo:
The specific high energy and power capacities of rechargeable lithium metal (Li0) batteries are ideally suited to portable devices and are valuable as storage units for intermittent renewable energy sources. Lithium, the lightest and most electropositive metal, would be the optimal anode material for rechargeable batteries if it were not for the fact that such devices fail unexpectedly by short-circuiting via the dendrites that grow across electrodes upon recharging. This phenomenon poses a major safety issue because it triggers a series of adverse events that start with overheating, potentially followed by the thermal decomposition and ultimately the ignition of the organic solvents used in such devices.
In this thesis, we developed experimental platform for monitoring and quantifying the dendrite populations grown in a Li battery prototype upon charging under various conditions. We explored the effects of pulse charging in the kHz range and temperature on dendrite growth, and also on loss capacity into detached “dead” lithium particles.
Simultaneously, we developed a computational framework for understanding the dynamics of dendrite propagation. The coarse-grained Monte Carlo model assisted us in the interpretation of pulsing experiments, whereas MD calculations provided insights into the mechanism of dendrites thermal relaxation. We also developed a computational framework for measuring the dead lithium crystals from the experimental images.
Resumo:
Part I
The infection of E. coli by ΦX174 at 15°C is abortive; the cells are killed by the infection but neither mature phage nor SS (single-stranded) DNA are synthesized. Parental RF (replicative form) is formed and subsequently replicated at 15°C. The RF made at 15°C shows normal infectivity and full competence to act as precursor to progeny SS DNA after an increase in temperature to 37°C. The investigations suggest that all of the proteins required for SS DNA synthesis and phage maturation are present in the abortive infection at 15°C.
Three possible causes are suggested for the abortive infection at 15°C: (a) A virus-coded protein whose role is essential to the infection is made at 15°C and assumes its native conformation, but its rate of activity is too low at this temperature to sustain the infection process. (b) Virus maturation may involve the formation of a DNA-protein complex and conformational changes which have an energy threshold infrequently reached at 15°C. (c) A host-coded protein present in uninfected cells, and whose activity is essential to the infection at all temperatures, but not to the host at 15°C, is inactive at 15°C. An hypothesis of this type is offered which proposes that the temperature-limiting factor in SS DNA synthesis in vivo may reflect a temperature-dependent property of the host DNA polymerase.
Part II
Three distinct stages are demonstrated in the process whereby ΦX174 invades its host: (1) Attachment: The phage attach to the cell in a manner that does not irreversibly alter the phage particle and which exhibits "single-hit" kinetics. The total charge on the phage particle is demonstrated to be important in determining the rate at which stable attachment is effected. The proteins specified by ΦX cistrons II, III and VII play roles, which may be indirect, in the attachment reaction. (2) Eclipse: 'The attached phage undergo a conformational change. Some of the altered phage particles spontaneously detach from the cell (in a non-infective form) while the remainder are more tightly bound to the cell. The altered phage particles detached (spontaneously or chemically) from such complexes have at least 40% of their DNA extruded from the phage coat. It is proposed that this particle is, or derives from, a direct intermediate in the penetration of the viral DNA.
The kinetics for the eclipse of attached phage particles are first-order with respect to phage concentration and biphasic; about 85% of the phage eclipse at one rate (k = 0.86 min-1) and the remainder do so at a distinctly lesser rate (k = 0.21 min-1).
The eclipse event is very temperature-dependent and has the relatively high Arrhenius activation energy of 36.6 kcal/mole, indicating the cooperative nature of the process. The temperature threshold for eclipse is 17 to 18°C.
At present no specific ΦX cistron is identified as affecting the eclipse process. (3) DNA penetration: A fraction of the attached, eclipsed phage particles corresponding in number to the plaque-forming units complete DNA penetration. The penetrated DNA is found in the cell as RF, and the empty phage protein coat remains firmly attached to the exterior of the cell. This step is inhibited by prior irradiation of the phage with relatively high doses of UV light and is insensitive to the presence of KCN and NaN3. Temporally excluded superinfecting phages do not achieve DNA penetration.
Both eclipsed phage particles and empty phage protein coats may be dissociated from infected cells; some of their properties are described.
Resumo:
A obra romanesca de Mia Couto é o objeto da investigação desta tese, ponto de partida para tentar compreender a contribuição do autor na afirmação do romance africano e na reconstrução da identidade de seu país, Moçambique. Para tanto, o estudo discute a importância da revelação de uma paisagem oculta ao leitor, de matriz cultural e complexo entendimento. O capítulo que traz esta análise mostra como a obra retrata as condições históricas e políticas de dominação, desigualdade, identificando aqui e lá um tom levemente engajado na escrita miacoutiana, tanto quanto suas posições ideológicas, suas denúncias. Entre os temas mais destacados na obra está o animismo africano que dá origem a uma série de circunstâncias sobrenaturais nos enredos, como uma lembrança constante: em África, os espíritos estão por toda a parte, mantendo intensa relação com os vivos. Em torno da questão, a tese discute o fato de parte da crítica classificar a obra por gêneros como o Realismo Mágico, o Maravilhoso e o Fantástico. Também são investigadas as estratégias narrativas deste autor, suas opções regulares na composição de enredos, personagens, nomes de personagens e epígrafes. Com base nessas marcas e em outros traços comuns a todos os seus romances talvez presentes igualmente em seus contos descobre-se a adequação entre a criação de um sistema de pensamento dicotômico, que atravessa a obra, e estruturas frasais que revelam algo significativo: os romances de Mia Couto são propositivos, especialmente quando convidam o leitor ao movimento constante de questionamento de suas próprias certezas
Resumo:
Discutem-se os processos de trabalho e de produção do cuidado dos auxiliares e técnicos de enfermagem do Núcleo de Atenção à Crise do Instituto Municipal de Assistência à Saúde Nise da Silveira, no contexto da desinstitucionalização, e seus efeitos na integralidade do cuidado. O foco de análise repousa sobre o cuidado cotidiano prestado por esses profissionais nas unidades de internação psiquiátrica. Buscou-se realizar uma reflexão sobre os aspectos contemporâneos do cotidiano da assistência psiquiátrica e o papel dos hospitais psiquiátricos no atendimento aos pacientes agudos. Para tal objetivou-se, especificamente: contextualizar o IMNS no cenário de saúde mental no município do Rio de Janeiro; descrever as práticas assistenciais de auxiliares e técnicos de enfermagem no cuidado aos pacientes agudos internados; e discutir as práticas de cuidado no contexto da reorientação do modelo hospitalar e suas repercussões na integralidade da assistência em saúde, buscando contradições e aproximações com o discurso da política de saúde mental vigente. Foram abordadas na fundamentação teórica: as questões da prática da equipe de saúde sob o eixo da integralidade, em especial da equipe de enfermagem, e a relação trabalho/saúde/cotidiano na construção dos processos de trabalho e de produção do cuidado da assistência prestada. Como abordagem teórico-metodológica que possibilitou alcançar o objetivo proposto, realizou-se estudo exploratório, de natureza qualitativa, na perspectiva da cartografia, tendo na observação participante seu principal elemento de coleta de dados. O mapeamento das práticas rotineiras de cuidado evidenciou que estas são predominantemente pautadas no modelo asilar, no qual auxiliares e técnicos desempenham suas atividades diárias de modo distanciado dos pacientes e de suas necessidades. Esses profissionais não são vistos como elementos da equipe de saúde mental, e assim, desprestigiados em relação à política de formação e capacitação em saúde mental, assumem o cuidado aos pacientes institucionalizados de modo pouco estruturado, sem levar em consideração os anseios e sofrimentos dos usuários. Acolhimento, vínculo e integralidade fizeram parte do discurso oficial de reorganização da assistência, num contexto macroestrutural, mas ainda não se materializam nas práticas assistenciais da unidade de saúde pesquisada. A importância do estudo está pautada no fornecimento de subsídios para a formulação e implantação de ações que auxiliem na melhoria da gestão do trabalho em saúde mental. Sua justificativa se faz na medida em que essa área é permeada por conflitos e questões que interferem decisivamente na qualidade dos serviços prestados.
Resumo:
[ES]En una vivienda unifamiliar ya construida y sin conectar a la red eléctrica, situada en Oyón, en la provincia de Álava (al lado de Logroño), se pretenden instalar paneles solares fotovoltaicos en el tejado, de modo que sea autónoma energéticamente hablando. Debido a que se usa como segunda residencia, y básicamente en los meses de buen tiempo, puede ser una inversión interesante