Charge Fluctuations
Mostrando 1-12 de 22 artigos, teses e dissertações.
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1. Effect of electron inertial delay on Debye sheath formation
Present contribution deals with the role of weak but finite electron inertia on the sheath formation condition. As reported earlier this becomes effective when the ions' drift velocity exceeds the phase velocity of the acoustic wave fluctuations. Such situation has natural existence near the sheath edge. Keeping this in mind we have revisited the problem of
Brazilian Journal of Physics. Publicado em: 2010-09
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2. Estudos estruturais de histatina-5 e seu análogo, TOAC0-histatina-5: interação com metais e sistemas biomiméticos / Structural studies of Histatin-5 and its analogue, TOAC0-Histatin-5: interaction with metals and biomimetic systems
The mechanism of action of histatin-5 (Hst-5), an antifungal antimicrobial peptide from human saliva is not completely clarified. Circular dichroism (CD), fluorescence, and electron paramagnetic resonance (EPR) were used to examine the conformational behavior of Hst-5 and its analogue containing the paramagnetic amino acid TOAC at the N-terminus (TOAC0-Hst-5
Publicado em: 2008
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3. FIRST-ORDER TRANSITION IN THE FERMIONIC ISING SPIN GLASS MODEL IN A TRANSVERSE FIELD / TRANSIÇÕES DE PRIMEIRA ORDEM NO MODELO VIDRO DE SPIN ISING FERMIÔNICO EM UM CAMPO TRANSVERSO
The present work analyzes the fermionic Ising spin glass model in a transverse magnetic field. The problem is written in the Grand Canonical ensemble with the spin operators represented by bilinear combinations of fermionic fields. The transverse field is a spin "flip" mechanism and inserts quantum fluctuations, which can lead the transition temperature Tj t
Publicado em: 2006
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4. New developments in the quantization of supersymmetric solitons (kinks, vortices and monopoles)
We discuss the one-loop quantum corrections to the mass M and central charge Z of supersymmetric (susy) solitons: the kink, the vortex and the monopole. Contrary to previous expectations and published results, in each of these cases there are nonvanishing quantum corrections to the mass. For the N = 1 kink and the N = 2 monopole a new anomaly in Z rescues BP
Brazilian Journal of Physics. Publicado em: 2004-12
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5. Distinguishing models for the pseudo-gap in cuprate superconductors by probing the spatial distribution of impurity states
We argue that the spatial distribution of resonant impurity states in underdoped high-Tc superconductors serves as a probe for distinguishing different theoretical models for the pseudogap state. Superconducting pairing fluctuations are characterized by off-diagonal short-range order which distinguishes them from other possible instabilities that could give
Brazilian Journal of Physics. Publicado em: 2003-12
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6. Simulations of plasmas with electrostatic PIC models using the finite element method
Particle-in-cell (PIC) methods allow the study of plasma behavior by computing the trajectories of finite-size particles under the action of external and self-consistent electric and magnetic fields defined in a grid of points. In this work, the Finite Element Method (FEM) is used in order to obtain the self-consistent fields. An electrostatic PIC-FEM comput
Brazilian Journal of Physics. Publicado em: 2003-06
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7. Construction of and auto-balanced ac suceptometer and study of eletronic conductor polymers for magnetic susceptibility and magnetic resonance. / Construção de um Susceptômetro AC Autobalanceado e Estudo de Polímeros Condutores Eletrônicos por Susceptibilidade Magnética e Ressonância Magnética.
A mutual inductance bridge which may be used for automatic measurement of ac magnetic susceptibilities from 4 K to room temperature, at frequencies up to 1 kHz, is described. The susceptometer employs an alternative and new arrangement for the probe. The coil set is kept at room temperature and moves in such a way to place the sample in the center of each of
Publicado em: 1998
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8. Flutuações de composição em um elastomero dieletrico processado por extrusão
Dielectric polymer materials, such as the elastomers based on poly(ethylene/propylene/1,4-hexadiene), also called EPDM or ethylene-propylene rubbers, are normally used for the electric insulation of hiqh voltage cables. The dielectric strength of these materiaIs is one of the most significant properties for the evaluation of their performance, as a function
Publicado em: 1988
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9. SPECIFICITY OF INTERMOLECULAR FORCES DUE TO QUANTUM-MECHANICAL AND THERMAL CHARGE FLUCTUATIONS*
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10. Probing conformational dynamics in single donor-acceptor synthetic molecules by means of photoinduced reversible electron transfer
We use single-molecule fluorescence lifetimes to probe dynamics of photoinduced reversible electron transfer occurring between triphenylamine (donor) and perylenediimide (acceptor) in single molecules of a polyphenylenic rigid dendrimer embedded in polystyrene. Here, reversible electron transfer in individual donor-acceptor molecules results in delayed fluor
National Academy of Sciences.
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11. Polarizable molecules in the vibrational spectroscopy of water
We examine the role of electronic polarizability in water on short (tens of femtoseconds), intermediate (hundreds of femtoseconds), and long (≈1 ps) time scales by comparing molecular dynamics results to experimental data for vibrational spectroscopy of HOD in liquid D2O. Because the OH absorption frequency is sensitive to the details of the atomic forces
National Academy of Sciences.
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12. How frequent are correlated changes in families of protein sequences?
A loss-of-function point mutation in a protein is often rescued by an additional mutation that compensates for the original physical change. According to one hypothesis, such compensation would be most effective in maintaining a structural motif if the two mutated residues were spatial neighbors. If this hypothesis were correct, one would expect that many su