12,422 research outputs found
Classical Analog of Electromagnetically Induced Transparency
We present a classical analog for Electromagnetically Induced Transparency
(EIT). In a system of just two coupled harmonic oscillators subject to a
harmonic driving force we can reproduce the phenomenology observed in EIT. We
describe a simple experiment performed with two linearly coupled RLC circuits
which can be taught in an undergraduate laboratory class.Comment: 6 pages, two-column, 6 figures, submitted to the Am. J. Phy
Photoconductance of a submicron oxidized line in surface conductive single crystalline diamond
We report on sub-bandgap optoelectronic phenomena of hydrogen-terminated
diamond patterned with a submicron oxidized line. The line acts as an energy
barrier for the two-dimensional hole gas located below the hydrogenated diamond
surface. A photoconductive gain of the hole conductivity across the barrier is
measured for sub-bandgap illumination. The findings are consistent with
photogenerated electrons being trapped in defect levels within the barrier. We
discuss the spatial and energetic characteristics of the optoelectronic
phenomena, as well as possible photocurrent effects
Does the linguistic expectancy bias extend to a second language?
The linguistic expectancy bias (LEB) reflects the tendency to describe expectancy-consistent behavior more abstractly than expectancy-inconsistent. The current studies replicate the LEB in Portuguese and examine it in a second language (English). Earlier studies found differences in processing a first language (L1) and a second language (L2) shaping affective and cognitive processes. We did not expect these differences to shape the LEB because controlled lexical decisions (e.g., use of verbs and adjectives) are unlikely, even when using L2. Participants wrote stereotypically male or female behavioral descriptions for male and female targets. A new group of participants read those descriptions and was asked about their causes. Expectancy-consistent behavior was described more abstractly and shaped more dispositional inferences in L1 and L2. Aside from replicating the LEB in a different language, these studies indicate that structural features of language preserve a linguistic bias with implications for social perception even when using a second language.info:eu-repo/semantics/acceptedVersio
Bulk dynamics for interfacial growth models
We study the influence of the bulk dynamics of a growing cluster of particles
on the properties of its interface. First, we define a {\it general bulk growth
model} by means of a continuum Master equation for the evolution of the bulk
density field. This general model just considers arbitrary addition of
particles (though it can be easily generalized to consider substraction) with
no other physical restriction. The corresponding Langevin equation for this
bulk density field is derived where the influence of the bulk dynamics is
explicitly shown. Finally, when it is assumed a well-defined interface for the
growing cluster, the Langevin equation for the height field of this interface
for some particular bulk dynamics is written. In particular, we obtain the
celebrated Kardar-Parisi-Zhang (KPZ) equation. A Monte Carlo simulation
illustrates the theoretical results.Comment: 6 pages, 2 figure
Acumulación de Cu y Zn por célular microalgales marinas de Nannochloropsis gaditana (Eustigmatophyceae) inmovilizadas en alginato de calcio
13 páginas, 5 figuras, 2 tablas.[EN] Different experiments about the accumulation capacity for copper and zinc were carried out on the marine microalgae
Nannochloropsis gaditana Lubián (Eustigmatophyceae). A 24-hour study of the evolution of accumulated metal in the beads
revealed two possible accumulation phases. Accumulation differences between free and immobilized microalgal cells were
investigated finding no differences for copper, and little differences for zinc. Free cells accumulated practically 100% Cu or Zn in
the media under experimental conditions. Experiments in order to compare the accumulation capacity of living vs. dead cells were
designed too, obtaining the largest accumulation levels for both metals in the beads containing immobilized living microalgae. In
experiments carried out in continuous-flow reactors, beads with entrapped cells showed to be more efficient removing Cu and Zn
than beads without cells. In all the experiments, the calcium alginate beads showed strong affinity for Cu. Similar results were
obtained when accumulation by packed beads in columns was tested, but efficacy was higher if this design was used (beads with
cells retain 80% of Cu introduced in the column).[ES] Se han realizado distintos experimentos sobre la capacidad de acumulación de cobre y zinc por parte de la microalga marina
Nannochloropsis gaditana Lubián (Eustigmatophyceae). Un estudio de la evolución del metal acumulado durante 24 horas reveló
la existencia de dos posibles fases de acumulación. Se investigaron las diferentes capacidades de acumulación de células
microalgales libres e inmovilizadas, no encontrándose diferencias para el cobre y pequeñas diferencias para el zinc. Las células
libres acumularon prácticamente el 100% del Cu o Zn presentes en el medio, en las condiciones experimentales. Se desarrollaron
experimentos encaminados a determinar la capacidad de acumulación de estos metales por parte de algas inmovilizadas vivas
frente a la de algas inmovilizadas muertas, encontrándose los niveles acumulativos más altos para ambos metales en las gotas de
alginato que contenían algas vivas. En experimentos realizados en reactores de flujo continuo, las gotas de alginato con células
inmovilizadas en su interior demostraron ser más eficientes en cuanto a la retirada de Cu y Zn del medio que las gotas sin algas.
En todos los experimentos realizados se observa una fuerte afinidad del Cu por el alginato de calcio. Se obtuvieron resultados
similares cuando se ensayó la acumulación de metales en gotas de alginato dispuestas en columnas llenas, aunque la eficacia fue
mayor cuando se usó este último diseño (las gotas de alginato con células retuvieron el 80% del Cu introducido en la columna).Peer reviewe
Three-body structure of low-lying 18Ne states
We investigate to what extent 18Ne can be descibed as a three-body system
made of an inert 16O-core and two protons. We compare to experimental data and
occasionally to shell model results. We obtain three-body wave functions with
the hyperspherical adiabatic expansion method. We study the spectrum of 18Ne,
the structure of the different states and the predominant transition strengths.
Two 0+, two 2+, and one 4+ bound states are found where they are all known
experimentally. Also one 3+ close to threshold is found and several negative
parity states, 1-, 3-, 0-, 2-, most of them bound with respect to the 16O
excited 3- state. The structures are extracted as partial wave components, as
spatial sizes of matter and charge, and as probability distributions.
Electromagnetic decay rates are calculated for these states. The dominating
decay mode for the bound states is E2 and occasionally also M1.Comment: 17 pages, 5 figures (version to appear in EPJA
A Study of Two-Temperature Non-Equilibrium Ising Models: Critical Behavior and Universality
We study a class of 2D non-equilibrium Ising models based on competing
dynamics induced by contact with heat-baths at two different temperatures. We
make a comparative study of the non-equilibrium versions of Metropolis, heat
bath/Glauber and Swendsen-Wang dynamics and focus on their critical behavior in
order to understand their universality classes. We present strong evidence that
some of these dynamics have the same critical exponents and belong to the same
universality class as the equilibrium 2D Ising model. We show that the bond
version of the Swendsen-Wang update algorithm can be mapped into an equilibrium
model at an effective temperature.Comment: 12 pages of LaTeX plus 18 pages of postscript figures in a uuencoded
file (608k
Absence of a Finite-Temperature Melting Transition in the Classical Two-Dimensional One-Component Plasma
Vortices in thin-film superconductors are often modelled as a system of
particles interacting via a repulsive logarithmic potential. Arguments are
presented to show that the hypothetical (Abrikosov) crystalline state for such
particles is unstable at any finite temperature against proliferation of
screened disclinations. The correlation length of crystalline order is
predicted to grow as as the temperature is reduced to zero, in
excellent agreement with our simulations of this two-dimensional system.Comment: 3 figure
Non-equilibrium Anisotropic Phases, Nucleation and Critical Behavior in a Driven Lennard-Jones Fluid
We describe short-time kinetic and steady-state properties of the
non--equilibrium phases, namely, solid, liquid and gas anisotropic phases in a
driven Lennard-Jones fluid. This is a computationally-convenient
two-dimensional model which exhibits a net current and striped structures at
low temperature, thus resembling many situations in nature. We here focus on
both critical behavior and details of the nucleation process. In spite of the
anisotropy of the late--time spinodal decomposition process, earlier nucleation
seems to proceed by Smoluchowski coagulation and Ostwald ripening, which are
known to account for nucleation in equilibrium, isotropic lattice systems and
actual fluids. On the other hand, a detailed analysis of the system critical
behavior rises some intriguing questions on the role of symmetries; this
concerns the computer and field-theoretical modeling of non-equilibrium fluids.Comment: 7 pages, 9 ps figures, to appear in PR
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