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Quantização da partícula não relativística em espaços curvos como superfícies do Rn; Quantization of the non-relativistic particle in curved spaces as surfaces of Rn

Resende, Maria Fernanda Araujo de
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 16/11/2011 PT
Relevância na Pesquisa
35.95%
Neste trabalho estudamos o problema relacionado à construção de uma teoria quântica para uma partícula, se movendo não relativisticamente num espaço curvo, tratado como uma subvariedade de outro Euclideano, talvez dando maior ênfase ao aspecto geométrico envolvido nesta abordagem, uma vez que os demais trabalhos relacionados ao mesmo tema não o fazem. Além de mostrarmos que o consequente uso de uma teoria de sistemas vinculados não contribui para remover as ambiguidades da formulação quântica, relacionados diretamente ao ordenamento de operadores, também apresentamos, através de uma quantização específica feita sob a prescrição de Dirac, elementos que permitem não apenas construir um formalismo quântico covariante, mas também liberto de qualquer correção quântica. Em adição, fazemos alguns comentários gerais no que se refere às outras abordagens clássicas possíveis para o mesmo problema, intentando construir teorias quânticas associadas ao sistema sob consideração.; In this work we study the problem related to the construction of a quantum theory for a particle, moving non-relativistically in a curved space, treated as submanifold of the other Euclidean, maybe putting more emphasis on the geometric aspect envolved in this approach...

Investigação cinética de modos geodésicos de baixas frequências em plasmas magnetizados; Kinetic investigation of low frequency geodesic modes in magnetized plasmas

Sgalla, Reneé Jordashe Franco
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 29/07/2014 PT
Relevância na Pesquisa
16.03%
Devido à sua importância em turbulência causada por ondas de deriva e à aplicação com propósitos em diagnósticos de plasma, a investigação de fluxos zonais (ZF) e modos acústicos geodésicos (GAM) tem atraído bastante atenção na literatura em física de plasmas. Nesta tese, primeiramente consideramos efeitos de equilíbrio com rotação poloidal e toroidal nestes modos, posteriormente investigamos efeitos diamagnéticos em GAM a partir de um modelo de dois fluido, no qual incluímos viscosidade paralela de íons e, na parte final, consideramos amortecimento de Landau e efeitos diamagnéticos simultaneamente no estudo de GAM, porém, a partir do modelo girocinético. Efeitos diamagnéticos são causados por termos que envolvem gradientes de densidade e de temperatura provenientes da função Maxwelliana de equilíbrio. O acoplamento entre os harmônicos poloidais, $m = \pm1$, e as derivadas radiais de quantidades macroscópicas do plasma é responsável pelo aumento no valor da frequência no GAM de alta frequência e pela instabilidade no GAM de baixa frequência. Este tipo de instabilidade, que é proporcional à frequência diamagnética de elétrons e à razão entre os gradientes de temperatura e de densidade...

Compositional analysis for an unbiased measure of soil aggregation

Parent, Leon E.; de Almeida, Cinara X.; Hernandes, Amanda; Egozcue, Juan J.; Gulser, Coskun; Bolinder, Martin A.; Katterer, Thomas; Andren, Olof; Parent, Serge E.; Anctil, Francois; Centurion, Jose F.; Natale, William
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Outros Formato: 123-131
ENG
Relevância na Pesquisa
26.03%
Soil aggregation is an index of soil structure measured by mean weight diameter (MWD) or scaling factors often interpreted as fragmentation fractal dimensions (D-f). However, the MWD provides a biased estimate of soil aggregation due to spurious correlations among aggregate-size fractions and scale-dependency. The scale-invariant D-f is based on weak assumptions to allow particle counts and sensitive to the selection of the fractal domain, and may frequently exceed a value of 3, implying that D-f is a biased estimate of aggregation. Aggregation indices based on mass may be computed without bias using compositional analysis techniques. Our objective was to elaborate compositional indices of soil aggregation and to compare them to MWD and D-f using a published dataset describing the effect of 7 cropping systems on aggregation. Six aggregate-size fractions were arranged into a sequence of D-1 balances of building blocks that portray the process of soil aggregation. Isometric log-ratios (ilrs) are scale-invariant and orthogonal log contrasts or balances that possess the Euclidean geometry necessary to compute a distance between any two aggregation states, known as the Aitchison distance (A(x,y)). Close correlations (r>0.98) were observed between MWD...

Novo design de laminados oclusais ultrafinos CAD/CAM de resina composta e cerâmica para o tratamento de erosão severa

Schlichting, Luís Henrique
Fonte: Universidade Federal de Santa Catarina Publicador: Universidade Federal de Santa Catarina
Tipo: Tese de Doutorado Formato: 163 p.| il., grafs., tabs.
POR
Relevância na Pesquisa
16.25%
Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde, Programa de Pós-Graduação em Odontologia, Florianópolis, 2010; O objetivo deste estudo foi avaliar a influência de materiais para processamento CAD/CAM (cerâmica vs. resina composta) na resistência à fadiga de laminados oclusais ultrafinos (0,6 mm) e finos (1,2 mm). Setenta molares extraídos receberam um preparo não retentivo padronizado (simulando erosão oclusal avançada) onde o esmalte oclusal foi removido e a dentina exposta foi imediatamente selada (Optibond FL). Por intermédio do sistema Cerec 3 (Sirona), 40 dentes foram restaurados com laminados oclusais de 0,6 mm de espessura e 30 deles com 1,2 mm de espessura. As cerâmicas reforçadas Empress CAD (grupos ECAD06 e ECAD12) e e.max CAD (grupos EMAX06 e EMAX12) e a resina composta Paradigm MZ100 (grupos MZ06 e MZ12) foram utilizadas na usinagem das restaurações (n=10). Uma resina composta experimental (grupo XR06) também foi incluída somente para a espessura 0,6 mm (n=10). A superfície interna das restaurações foi condicionada com ácido fluorídrico e silanizada (cerâmicas) ou microjateada com óxido de alumínio e silanizada (resinas compostas). Os preparos foram microjateados e condicionados com ácido fosfórico antes da inserção das restaurações. Todas as restaurações foram cimentadas adesivamente pré-aquecendo-se a resina composta Filtek Z100. Esforços cíclicos isométricos foram aplicados à frequência de 5 Hz...

Avaliação da resistência à fadiga e do modo de fratura de restaurações adesivas implantossuportadas em cerâmica e resina composta sobre pilares personalizados de zircônia para região de pré-molares

Oderich, Elisa
Fonte: Universidade Federal de Santa Catarina Publicador: Universidade Federal de Santa Catarina
Tipo: Tese de Doutorado Formato: 181 p.| il., tabs., grafs.
POR
Relevância na Pesquisa
15.95%
Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde, Programa de Pós-Graduação em Odontologia, Florianópolis, 2011; Esse estudo avaliou a resistência à fadiga e o modo de fratura de restaurações adesivas implantossuportadas confeccionadas de cerâmica e resina composta sobre pilares personalizados de zircônia para região de pré-molares com dois designs distintos, para coroas e onlays. Foram obtidos 60 pilares personalizados apresentando dois preparos distintos (coroa ou onlay). As restaurações correspondentes foram fabricadas pelo sistema CAD/CAM (Cerec 3) em cerâmica (Paradigm C) ou resina composta (Paradigm MZ100) totabilizando 4 grupos experimentais, n=15. As superfícies adesivas dos pilares foram jateadas com Al2O3. As superfícies internas das restaurações foram condicionadas com ácido hidrofluorídrico e silanizadas (Paradigm C) ou jateadas e silanizadas (Paradigm MZ100). O protocolo adesivo após o aparafusamento do pilar sobre o implante (Titamax CM) constava no uso de primer para zircônia (Z-Prime Plus), adesivo (Optibond FL) e resina composta fotopolimerizável pré-aquecida (Filtek Z100). Foi simulado o movimento mastigatório cíclico e isométrico (5Hz) com carga de 50N (5000x)...

(Paleo)ecology of coccolithophores in the submarine canyons of the central portuguese continental margin:environmental, sedimentary and oceanographic implications

Guerreiro, Catarina Alexandra Vicente, 1978-
Fonte: Universidade de Lisboa Publicador: Universidade de Lisboa
Tipo: Tese de Doutorado
Publicado em //2013 ENG
Relevância na Pesquisa
16.03%
Tese de doutoramento, Geologia (Paleontologia e Estatigrafia), Universidade de Lisboa, Faculdade de Ciências, 2013; This thesis aims to contribute to the knowledge of coccolithophores from coastal-neriticoceanic transitional settings, their distribution offshore central Portugal, and their potential as (paleo)ecological and (paleo)ceanographic proxy in the context of submarine canyons. In order to achieve a good understanding of the relationship of coccolithophores with the environmental setting, results were interpreted on a multidisciplinary basis, integrating a significant data set concerning the hydrological characteristics of surface waters of the central Portuguese margin (i.e. nutrients, chlorophyll, temperature, salinity, turbidity, wind data) and seabed sedimentological characteristics (i.e. sediment bulk composition, particle size and sediment accumulation). The most striking variations in phytoplankton communities off central Portugal occurred along the coastal-oceanic lateral gradient. Two principal groups of taxa of opposite ecological behaviour were observed in the photic layer, with K-selected taxa preferentially distributed in the open ocean, and r-selected taxa preferentially occurring in more coastal-neritic regions. Such gradient was also reflected in coccolith assemblages preserved in surface sediments on the seabed...

A study of the pneumatic conveying of non-spherical particles in a turbulent horizontal channel flow

Laín,S.; Sommerfeld,M.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2007 EN
Relevância na Pesquisa
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In this work, the pneumatic conveying of non-spherical isometric particles with different degrees of non-sphericity is studied. The solids mass loading fraction is small enough in order to have a dilute flow, so inter-particle collisions can be neglected. As a first approximation, only the aerodynamic drag force acting on the particles is considered, neglecting the lift forces and the particle rotation. The drag coefficient is calculated using the correlations of Haider and Levenspiel (1989) and Ganser (1993). The numerical simulations are compared with experimental data in a narrow six meters long horizontal channel flow laden with quartz and duroplastic particles with mean diameters of 185 and 240 mu m, respectively (Kussin, 2004).

Length and shape variants of the bacteriophage T4 head: mutations in the scaffolding core genes 68 and 22.

Keller, B; Dubochet, J; Adrian, M; Maeder, M; Wurtz, M; Kellenberger, E
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /08/1988 EN
Relevância na Pesquisa
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The shape and size of the bacteriophage T4 head are dependent on genes that determine the scaffolding core and the shell of the prohead. Mutants of the shell proteins affect mainly the head length. Two recently identified genes (genes 67 and 68) and one already known gene (gene 22), whose products are scaffold constituents, have been investigated. Different types of mutants were shown to strongly influence the proportion of aberrantly shaped particles. By model building, these shape variants could be represented as polyhedral bodies derived from icosahedra, through outgrowths along different polyhedral axes. The normal, prolate particle is obtained by elongation along a fivefold axis. The mutations of the three core genes (genes 67, 68, and 22) affect the width mainly by lateral outgrowths of the prolate particle, although small and large isometric particles are also found. Many of the aberrant particles are multitailed, suggesting a correlation between tail attachment sites and shape.

Cryo-reconstructions of P22 polyheads suggest that phage assembly is nucleated by trimeric interactions among coat proteins

Parent, Kristin N; Sinkovits, Robert S; Suhanovsky, Margaret M; Teschke, Carolyn M; Egelman, Edward H; Baker, Timothy S
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 09/12/2010 EN
Relevância na Pesquisa
26.13%
Bacteriophage P22 forms an isometric capsid during normal assembly, yet when the coat protein (CP) is altered at a single site, helical structures (polyheads) also form. The structures of three distinct polyheads obtained from F170L and F170A variants were determined by cryo-reconstruction methods. An understanding of the structures of aberrant assemblies such as polyheads helps to explain how amino acid substitutions affect the CP, and these results can now be put into the context of CP pseudo-atomic models. F170L CP forms two types of polyhead and each has the CP organized as hexons (oligomers of six CPs). These hexons have a skewed structure similar to that in procapsids (precursor capsids formed prior to dsDNA packaging), yet their organization differs completely in polyheads and procapsids. F170A CP forms only one type of polyhead, and though this has hexons organized similarly to hexons in F170L polyheads, the hexons are isometric structures like those found in mature virions. The hexon organization in all three polyheads suggests that nucleation of procapsid assembly occurs via a trimer of CP monomers, and this drives formation of a T = 7, isometric particle. These variants also form procapsids, but they mature quite differently: F170A expands spontaneously at room temperature...

Two viruses from adult honey bees (Apis mellifera Linnaeus)

Bailey, L.; Gibbs, A.J.; Woods, R.D.
Fonte: INRA - Instituto Nacional de Investigação Agronômica da França Publicador: INRA - Instituto Nacional de Investigação Agronômica da França
Tipo: Journal Article-postprint
EN; ENGLISH
Relevância na Pesquisa
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Two viruses were isolated from honey bees. When fed to, sprayed on, or injected into healthy bees either virus made the bees become trembly within a few days, but whereas bees infected with one virus died quickly (acute “paralysis”), bees infected with the other survived for several days after first showing symptoms (chronic “paralysis”). Purified preparations of acute bee paralysis virus (ABPV) contained isometric particles about 28 mμ in diameter, whereas those of chronic bee paralysis virus (CBPV) contained particles of irregular shape about 27 × 45 mμ. Both viruses occurred in apparently healthy bees, but only CBPV particles were numerous in diseased bees from colonies naturally affected with the disease called “bee paralysis.” On inoculation to healthy bees the symptoms caused by CBPV resembled those of the naturally occurring disease more than did those caused by ABPV.

Multi-walled carbon nanotubes: sampling criteria and aerosol characterization

Chen, Bean T.; Schwegler-Berry, Diane; McKinney, Walter; Stone, Samuel; Cumpston, Jared L.; Friend, Sherri; Porter, Dale W.; Castranova, Vincent; Frazer, David G.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/2012 EN
Relevância na Pesquisa
16.15%
This study intends to develop protocols for sampling and characterizing multi-walled carbon nanotube (MWCNT) aerosols in workplaces or during inhalation studies. Manufactured dry powder containing MWCNT’s, combined with soot and metal catalysts, form complex morphologies and diverse shapes. The aerosols, examined in this study, were produced using an acoustical generator. Representative samples were collected from an exposure chamber using filters and a cascade impactor for microscopic and gravimetric analyses. Results from filters showed that a density of 0.008–0.10 particles per µm2 filter surface provided adequate samples for particle counting and sizing. Microscopic counting indicated that MWCNT’s, resuspended at a concentration of 10 mg/m3, contained 2.7 × 104 particles/cm3. Each particle structure contained an average of 18 nanotubes, resulting in a total of 4.9 × 105 nanotubes/cm3. In addition, fibrous particles within the aerosol had a count median length of 3.04 µm and a width of 100.3 nm, while the isometric particles had a count median diameter of 0.90 µm. A combination of impactor and microscopic measurements established that the mass median aerodynamic diameter of the mixture was 1.5 µm. It was also determined that the mean effective density of well-defined isometric particles was between 0.71 and 0.88 g/cm3...

Particle Creation in the Bell-Szekeres Spacetime

Feinstein, A.; Sebastián, M. A. Pérez
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 24/11/1995
Relevância na Pesquisa
25.83%
The quantization of a real massless scalar field in a spacetime produced in a collision of two electromagnetic plane waves with constant wave fronts is considered. The background geometry in the interaction region, the Bell-Szekeres solution, is locally isometric to the conformally flat Bertotti-Robinson universe filled with a uniform electric field. It is shown that before the waves interact the Bogoliubov coefficients relating different observers are trivial and no vacuum polarization takes place. In the non- singular interaction region neutral scalar particles are produced with number of created particles and spectrum typical of gravitational wave collision.; Comment: 18 pages. To appear in Class. Quantum Grav. 12, November (1995)

Coherent States for Transparent Potentials

Samsonov, Boris F.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 26/04/1999
Relevância na Pesquisa
16.21%
Darboux transformation operators that produce multisoliton potentials are analyzed as operators acting in a Hilbert space. Isometric correspondence between Hilbert spaces of states of a free particle and a particle moving in a soliton potential is established. It is shown that the Darboux transformation operator is unbounded but closed and can not realize an isometric mapping between Hilbert spaces. A quasispectral representation of such an operator in terms of continuum bases is obtained. Different types of coherent states of a multisoliton potential are introduced. Measures that realize the resolution of the identity operator in terms of the projectors on the coherent states vectors are calculated. It is shown that when these states are related with free particle coherent states by a bounded symmetry operator the measure is defined by ordinary functions and in the case of a semibounded symmetry operator the measure is defined by a generalized function.

Geometry of 2d spacetime and quantization of particle dynamics

Jorjadze, George; Piechocki, Włodzimierz
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 30/11/1998
Relevância na Pesquisa
25.95%
We analyze classical and quantum dynamics of a particle in 2d spacetimes with constant curvature which are locally isometric but globally different. We show that global symmetries of spacetime specify the symmetries of physical phase-space and the corresponding quantum theory. To quantize the systems we parametrize the physical phase-space by canonical coordinates. Canonical quantization leads to unitary irreducible representations of $SO_\uparrow (2.1)$ group.; Comment: 12 pages, LaTeX2e, submitted for publication

Two black hole initial data

Leski, Szymon
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
16.03%
Misner initial data are a standard example of time-symmetric initial data with two apparent horizons. Compact formulae describing such data are presented in the cases of equal or non-equal masses (i.e. isometric or non-isometric horizons). The interaction energy in the "Schwarzschild + test particle" limit of the Misner data is analyzed.; Comment: 4 pages, RevTeX4, journal version, a reference added, minor corrections

Geometry of Schroedinger Space-Times II: Particle and Field Probes of the Causal Structure

Blau, Matthias; Hartong, Jelle; Rollier, Blaise
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 05/05/2010
Relevância na Pesquisa
25.83%
We continue our study of the global properties of the z=2 Schroedinger space-time. In particular, we provide a codimension 2 isometric embedding which naturally gives rise to the previously introduced global coordinates. Furthermore, we study the causal structure by probing the space-time with point particles as well as with scalar fields. We show that, even though there is no global time function in the technical sense (Schroedinger space-time being non-distinguishing), the time coordinate of the global Schroedinger coordinate system is, in a precise way, the closest one can get to having such a time function. In spite of this and the corresponding strongly Galilean and almost pathological causal structure of this space-time, it is nevertheless possible to define a Hilbert space of normalisable scalar modes with a well-defined time-evolution. We also discuss how the Galilean causal structure is reflected and encoded in the scalar Wightman functions and the bulk-to-bulk propagator.; Comment: 32 pages

Isometric Entanglement of Particle Positions in Quantum Bound Systems

Ducharme, Robert J.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 17/10/2010
Relevância na Pesquisa
26.21%
It is shown the role of a scalar potential in the Schr\"{o}dinger equation for a steady-state two-particle system is equivalent to an isometric entanglement of the position coordinates of the particles in space and time. The entangled coordinates of each particle are complex quantities related through the entangling transformation to the real positions of both particles. The transformation takes into account all of the states in the Hilbert space of the composite system. Transforming the Schr\"{o}dinger equation into these entangled coordinates eliminates the scalar potential.; Comment: 7 pages

Minimizing properties of critical points of quasi-local energy

Chen, PoNing; Wang, Mu-Tao; Yau, Shing-Tung
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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In relativity, the energy of a moving particle depends on the observer, and the rest mass is the minimal energy seen among all observers. The Wang-Yau quasi-local mass for a surface in spacetime introduced in [7] and [8] is defined by minimizing quasi-local energy associated with admissible isometric embeddings of the surface into the Minkowski space. A critical point of the quasi-local energy is an isometric embedding satisfying the Euler-Lagrange equation. In this article, we prove results regarding both local and global minimizing properties of critical points of the Wang-Yau quasi-local energy. In particular, under a condition on the mean curvature vector we show a critical point minimizes the quasi-local energy locally. The same condition also implies that the critical point is globally minimizing among all axially symmetric embedding provided the image of the associated isometric embedding lies in a totally geodesic Euclidean 3-space.; Comment: Accepted by Comm. Math. Phys

Effects of Particle sizes, Non-Isometry and Interactions in Compressible Polymer Mixtures

Gujrati, P. D.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 28/08/2003
Relevância na Pesquisa
25.83%
We consider in this review the statistical mechanical description of a very general microscopic lattice model of a compressible and interacting multi-component mixture of linear polymers of fixed lengths. The model contains several microscopic, i.e. bare parameters determining the thermodynamic state of the system. General arguments are given to show that these parameters must be independent not only of the lattice properties but also of the thermodynamic state, and that the voids representing free volume must be carefully treated, if thermodynamics has to be properly obeyed. These facts have not always been appreciated in the literature. We focus on mixing functions, some of which have not been properly calculated in the literature. In general, mixing is non-isometric (non-zero volume of mixing) and the entropy of mixing is non-ideal. We have recently developed a lattice theory for the general model, which goes beyond the random mixing approximation (RMA) limit and is thermodynamically consistent in the entire parameter space. The theory contains terms that do not have a continuum analog except in the RMA limit or for point-like particles. Both the free volume and the total volume determine the thermodynamics of the system. The RMA limit of our theory gives rise to a new theory...

Point massive particle in General Relativity

Katanaev, M. O.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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It is well known that the Schwarzschild solution describes the gravitational field outside compact spherically symmetric mass distribution in General Relativity. In particular, it describes the gravitational field outside a point particle. Nevertheless, what is the exact solution of Einstein's equations with $\delta$-type source corresponding to a point particle is not known. In the present paper, we prove that the Schwarzschild solution in isotropic coordinates is the asymptotically flat static spherically symmetric solution of Einstein's equations with $\delta$-type energy-momentum tensor corresponding to a point particle. Solution of Einstein's equations is understood in the generalized sense after integration with a test function. Metric components are locally integrable functions for which nonlinear Einstein's equations are mathematically defined. The Schwarzschild solution in isotropic coordinates is locally isometric to the Schwarzschild solution in Schwarzschild coordinates but differs essentially globally. It is topologically trivial neglecting the world line of a point particle. Gravity attraction at large distances is replaced by repulsion at the particle neighbourhood.; Comment: 15 pages, references added, 1 figure