Navegação Ciências Exatas e da Terra por Título
Resultados 4270-4289 de 5973
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Quantification of porosity evolution from unaltered to propylitic-altered granites: the 14 C-PMMA method applied on the hydrothermal system of Lavras do Sul, Brazil
(2007) [Artigo de periódico]Este trabalho é uma aplicação do método 14C-polimetilmetacrilato na comparação da evolução da porosidade entre granitos não alterados e propilitizados, utilizando amostras da região de Lavras do Sul, Brasil. Este método, ... -
Quantifying feedback from narrow line region outflows in nearby active galaxies II. Spatially resolved mass outflow rates for the QSO2 Markarian 34
(2018) [Artigo de periódico]We present spatially resolved mass outflow rate measurements (M˙ out) for the narrow line region of Markarian 34, the nearest Compton-thick type 2 quasar (QSO2). Spectra obtained with the Hubble Space Telescope and at ... -
Quantifying magnetic anisotropy dispersion : theoretical and experimental study of the magnetic properties of anisotropic FeCuNbSiB ferromagnetic films
(2015) [Artigo de periódico]We performed a theoretical and experimental investigation of the quasi-static magnetic properties of anisotropic systems. We considered a modified Stoner-Wohlfarth model to describe anisotropic systems, and a distribution ... -
Quantifying the impact of non-stationarity in reinforcement learning-based traffic signal control
(2021) [Artigo de periódico]In reinforcement learning (RL), dealing with non-stationarity is a challenging issue. However, some domains such as traffic optimization are inherently non-stationary. Causes for and effects of this are manifold. In ... -
Quantitative analysis of phenol and alkylphenols in brazilian coal tar
(2004) [Artigo de periódico]The main purpose of this work is the identification and quantification of phenolic compounds in coal tar samples from a ceramics factory in Cocal (SC), Brazil. The samples were subjected to preparative scale liquid ... -
Quantitative comparison between differential adhesion models and cell sorting in the presence and absence of fluctuations
(1995) [Artigo de periódico]We study the effect of inhibition of cell-membrane ruffling on cell sorting in experiments and simulations. We use aggregates of neural retinal and pigmented retinal cells obtained from chicken embryos and inhibit membrane ... -
Quantization of gauge-invariant theories through the dirac-bracket formalism
(1981) [Artigo de periódico]A physical system possessing first-class constraints is quantized by using the Dirac-bracket formalism. The main features of this quantization procedure are analyzed. The model enables us to present a situation where ... -
Quantum critical behavior and thermodynamics of the repulsive one-dimensional Hubbard model in a magnetic field
(2020) [Artigo de periódico]Even though the Hubbard model is one of the most fundamental models of highly correlated electrons, analytical and numerical data describing its thermodynamics at nonzero magnetization are relatively scarce. We present a ... -
Quantum criticality of spin-1 bosons in a one-dimensional harmonic trap
(2012) [Artigo de periódico]We investigate universal thermodynamics and quantum criticality of spin-1 bosons with strongly repulsive density-density and antiferromagnetic spin-exchange interactions in a one-dimensional harmonic trap. From the equation ... -
Quantum critical point in the spin glass-Kondo transition in heavy-fermion systems
(2004) [Artigo de periódico]The Kondo–spin glass competition is studied in a theoretical model of a Kondo lattice with an intrasite Kondo-type exchange interaction treated within the mean-field approximation, an intersite quantum Ising exchange ... -
Quantum density anomaly in optically trapped ultracold gases
(2020) [Artigo de periódico]Water, the substance of life, is known for its myriad of anomalous properties, whose origins are still the subject of intense debates. In order to provide a different insight into this problem, we show how its density ... -
Quantum dynamics of chiral fermions in a model with anomalous breaking of gauge invariance
(1986) [Artigo de periódico]We study the quantum dynamics of chiral fermion fields minimally coupled to a gauge field. The model, originally proposed by Jackiw and Rajaraman, is known to exhibit the anomalous breaking of gauge invariance, which leads ... -
Quantum electrodynamics with zero bare ferminon mass
(1964) [Artigo de periódico] -
Quantum phase transitions in an interacting atom-molecule boson model
(2010) [Artigo de periódico]We study the quantum phase transitions of a model that describes the interconversion of interacting bosonic atoms and molecules. Using a classical analysis, we identify a threshold coupling line separating a molecular phase ... -
Quantum phase transitions in Bose–Einstein condensates from a Bethe ansatz perspective
(2012) [Artigo de periódico]We investigate two solvable models for Bose–Einstein condensates and extract physical information by studying the structure of the solutions of their Bethe ansatz equations. A careful observation of these solutions for the ... -
Quantum Physics teaching and the theory of Social representations : investigating the presence of quantum mysticism concepts among high school students in the south of Brazil
(2023) [Artigo de periódico]The present work deals with possibilities for contribution of the Theory of Social Representations (TSR) as a reference for group learning, with techniques and methodologies that are specific to it, to facilitate the ... -
Quantum spherical spin glass : supersymmetry and annealing
(2007) [Artigo de periódico]We show that the effective action of the quantum spherical spin glass is invariant under a generalized form of Becchi-Rouet-Stora-Tyutin supersymmetry. The Ward identities associated with this invariance indicate that the ... -
Quantum spin glass : a replica-symmetric theory with positive entropy
(1986) [Artigo de periódico]In the present paper we present a detailed analysis of quantum effects in the spin-glass transition as described by a quantum Heisenberg analogue of the Sherrington-Kirkpatrick model. The spin operators are represented in ... -
A quantum toy-model for inelastic scattering and catalysis based on Bäcklund transformations
(2022) [Artigo de periódico]This work presents a scalar self-consistent quantum model for molecular simulation. This model employs Bäcklund transformations to eliminate the wave function from Klein-Gordon and Schrödinger-type equations. The nonlinear ... -
Quarkonium photoproduction in pp and AA collisions at the LHC
(2016) [Artigo de periódico]In this contribution we report on the investigations of the exclusive production of quarkonium states in proton-proton and nucleus-nucleus reactions at the LHC using the theoretical framework of the light-cone dipole ...