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Part of the global seawater delta oxygen-18 database from reference Frohlich 1988
No full textPart of the global seawater delta oxygen-18 database from reference Frohlich 198
Edward Frohlich expenses
No full textThis image reflects a letter written by Edward Frohlich and lists business expenses
Optical-phonon modes and Frohlich potential in quantum dots
No full textBy extending the microscopic dipole model on optical-phonon modes as applied in quantum wells and quantum wires, to rectangular quantum dots (QD), optical phonon modes and their accompanying Frohlich potentials in QD are calculated and classified. When the bulk phonon dispersion is ignored, the optical phonon modes in QD can be clearly divided into the confined LO- and TO-bulk-like modes and the extended interface-like modes. Among the interface-like modes, a special attention is given to the corner modes, whose anisotropic behavior is depicted in the long wavelength limit. Based on the numerical results, a set of analytical formula are proposed to approximately describe the bulk-like modes, for which both the optical displacements and Frohlich potentials vanish at the interfaces. (C) 2000 Elsevier Science Ltd. All rights reserved
Stability of Holstein and Frohlich bipolarons
No full textWe have investigated bipolaron formation in the Holstein-Hubbard and the Frohlich-Hubbard model on a discrete one-dimensional lattice. Phonon enriched basis has been generated by exploiting the idea of the Lang-Firsov transformation, which results in better convergence in the strong coupling regime. The incorporation of the finite-range electron-phonon (e-ph) interaction reduces the bipolaron effective mass. We systematically increase the spatial extent of the e-ph interaction to study the effect of the long-range tail of the Frohlich model. The electron-electron (e-e) interaction also plays a crucial role in lowering the effective mass for both the Holstein and the Frohlich bipolarons. In the presence of the extended e-e interaction, the intersite S1 Holstein bipolaron becomes unstable, while the effective mass of the Frohlich bipolaron becomes significantly reduced for both the spin singlet and triplet cases.open1166sciescopu
Lie-Schwinger block-diagonalization and gapped quantum chains
No full textWe study quantum chains whose Hamiltonians are perturbations by bounded interactions of short range of a Hamiltonian that does not couple the degrees of freedom located at different sites of the chain and has a strictly positive energy gap above its ground-state energy. We prove that, for small values of a coupling constant, the spectral gap of the perturbed Hamiltonian above its ground-state energy is bounded from below by a positive constant uniformly in the length of the chain. In our proof we use a novel method based on local Lie-Schwinger conjugations of the Hamiltonians associated with connected subsets of the chain
The time-evolution of states in quantum mechanics according to the ETH-approach
Get PDFIt is argued that the Schrodinger equation does not yield a correct description of the quantum-mechanical time evolution of states of isolated physical systems featuring events. A general statistical law replacing unitary Schrodinger evolution of states is then formulated within the so-called ETH-Approach to Quantum Mechanics. This law eliminates the infamous "measurement problem." Our general concepts and results are illustrated by an analysis of simple models describing a very heavy atom coupled to the quantized radiation field. In the limit where the speed of light tends to infinity these models can be treated quite explicitly
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Possible Frohlich superconductivity in strong magnetic fields.
Get PDFA brief review of some of the arguments pointing towards the possibility of organic conductors of the form {alpha}-(BEDT-TTF)&J3g(SCN)4 (where M=K, T1 and Rb) being candidates for Frohlich superconductivity is given
Uma Proposta de framework para a geração de protocolos MAC para RSSF
Get PDFDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Ciência da Computação, Florianópolis, 2013.Redes de sensores sem fio são altamente dependentes de protocolos de controle de acesso ao meio para fazer uso efetivo dos poucos recursos disponíveis em seus nós sensores. Entretanto a maioria das otimizações propostas nos protocolos existentes focam em segmentos específicos do espaço de projeto. O que é considerado como uma otimização por uma classe de aplicações pode representar uma forte limitação para outras. Um protocolo com o objetivo de cobrir uma ampla fração do universo de aplicações de redes sensores deve apresentar algum mecanismo de configurabilidade ou adaptabilidade. Nesse sentido surgiu o Configurable Medium Access Control (C-MAC) (WANNER; OLIVEIRA; FROHLICH, 2007). O C-MAC funciona como um framework de estratégias de controle de acesso ao meio, as quais podem ser combinadas para produzir protocolos específicos de aplicação. Através desse paradigma, programadores de aplicações podem criar novos serviços de comunicação sob demanda e experimentar diferentes parâmetros de comunicação, coletando métricas para identificar e ajustar o protocolo às suas necessidades. Contudo, a arquitetura original do C-MAC fornece um baixo reuso de seus componentes em software, dificultando e reduzindo sua configurabilidade. Esta dissertação apresenta a proposta, implementação e avaliação de uma nova arquitetura para o framework C-MAC. Através de uma análise das diferentes categorias de protocolos MAC para redes de sensores, foram identificadas características comuns e especificidades desses protocolos que foram consideradas no desenvolvimento do novo C-MAC. Além disso, o que era um único grande componente na arquitetura original, foi separado em diferentes microcomponentes e novos microcomponentes foram incluídos de forma a suportar mais funcionalidades. Dessa forma, a arquitetura proposta possibilita um maior reuso de seus componentes em software, fornecendo maior configurabilidade e, consequentemente, suportando mais aplicações.Abstract : Wireless sensor networks are highly dependent on medium access controlprotocols to make effective use of the few resources available on sensor nodes.Nevertheless, most of the optimizations proposed by existing protocols focuson specific segments of the design space. What is considered an optimizationby one class of applications can represent a strong limitation for others.A protocol aiming at covering a large fraction of the application universefor sensor networks must feature configuration or adaptation mechanisms.Therefore, the Configurable Medium Access Control (C-MAC) wascreated (WANNER; OLIVEIRA; FROHLICH, 2007). C-MAC is realized asa framework of medium access control strategies that can be combined toproduce application-specific protocols. Through this paradigm, applicationprogrammers can create new communication services on demand and experimentwith different communication parameters, collecting metrics to identifyand adjust the protocol to match their applications? requirements. Nonetheless,C-MAC original architecture provides low reuse of software components,hindering its configurability.This dissertation presents the proposal, implementation, and evaluation ofa new architecture for the framework C-MAC. Through the analysis of thedifferent categories of MAC protocols for sensor networks, common characteristicsand specificities of these protocols were identified and used in thedevelopment of the new C-MAC. Thus, the proposed architecture enables agreater reuse of its software components, providing greater configurabilityand, consequently, supporting a wider range of applications
Possible Frohlich superconductivity in strong magnetic fields
No full textA brief review of some of the arguments pointing towards the possibility of organic conductors of the form alpha-(BEDT-TTF)(2)MHg(SCN)(4) (where M = K, Tl and Rb) being candidates for Frohlich superconductivity is given. (C) 2002 Published by Elsevier Science B.V
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