1,721,035 research outputs found
Quantum Quenches in Integrable Field Theories
Full text linkWe study the non equilibrium time evolution of an integrable field theory in 1 + 1 dimensions after a sudden variation of a global parameter of the Hamiltonian. For a class of quenches defined in the text, we compute the long times limit of the one point function of a local operator as a series of form factors. Even if some subtleties force us to handle this result with care, there is a strong evidence that for long times the expectation value of any local operator can be described by a generalized Gibbs ensemble with a different effective temperature for each eigenmode
Phase coherence, inelastic scattering, and interaction corrections in pumping through quantum dots
No full textAdiabatic quantum pumping in noninteracting, phase coherent quantum dots is elegantly described by Brouwer's formula. Interactions within the dot, while suppressing phase coherence, make Brouwer's formalism inapplicable. In this Letter, we discuss the nature of the physical processes forcing a description of pumping beyond Brouwer's formula, and develop, using a controlled adiabatic expansion, a useful formalism to study the effect of interactions within a generic perturbative scheme. The pumped current consists of a first contribution, analogous to Brouwer's formula and accounting for the remanent coherence, and of interaction corrections describing inelastic scattering. We apply the formalism to study the effect of interaction with a bosonic bath on a resonant level pump and discuss the robustness of the quantization of the pumped charge in turnstile cycles. © 2008 The American Physical Society
Comment on "Decrease in the configurational entropy during a melt's polymerization" [Chem. Phys. 305 (2004) 231]
No full textSplitting Between Main and Secondary Relaxations in Mono-, Di-, and Tri-Epoxy Compounds
No full textWideband dielectric spectroscopy (10^2 - 2•10^10 Hz) was used to study the dynamics of mono-, di-, and tri-epoxide compounds from below to above the glass transition temperature, Tg. Dielectric spectra above Tg revealed the existence of two relaxations, a structural and a secondary process, which merge at the splitting temperature Ts, located some tenths of degrees above Tg. A d.c. conductivity contribution is also present. The glass transition phenomenon markedly affects the temperature dependence of both the dielectric strength and the low frequency slope of the secondary process. The prediction of the Stokes-Einstein-Debye (SED) model was verified for mono- and di-epoxide, while a fractional power law (FSED) replaces the SED relation in tri-epoxide for T<Ts. Moreover, a transition temperature TB~Ts between two different Vogel-Fulcher regimes was recognised in all systems. The overall picture of the dynamics of the systems is enriched and very recent ideas on the splitting between main and secondary relaxations are confirmed. Finally, the triepoxy compound shows an additional relaxation, which is masked by the conductivity contribution and it is slower than the structural one. Such relaxation seems to be related to the conductivity and it is found to follow the FSED law
ELASTIC CHARACTERIZATION OF POLY(3-N DECYLPYRROLE) THIN-FILMS BY BRILLOUIN LIGHT-SCATTERING
No full textThe first elastic characterization of processable electrically conductive polymer obtained by Brillouin scattering (BS) is presented. BS measurements are performed on samples of poly(3-n.decylpyrrole) in the form of supported thin films obtained from spinning. Elastic parameters, such as Young's modulus and Poisson's ratio, are derived from BS spectra and discussed in comparison with other related polymeric materials
High-Resolution tandem Farby-Perot interferometer for Ultra-Violet Brillouin scattering measurements
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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