29,915 research outputs found
Parafoveal-foveal overlap can facilitate ongoing word identification during reading: evidence from eye movements.
Readers continuously receive parafoveal information about the upcoming word in addition to the foveal information about the currently fixated word. Previous research (Inhoff, Radach, Starr, & Greenberg, 2000) showed that the presence of a parafoveal word that was similar to the foveal word facilitated processing of the foveal word. We used the gaze-contingent boundary paradigm (Rayner, 1975) to manipulate the parafoveal information that subjects received before or while fixating a target word (e.g., news) within a sentence. Specifically, a reader's parafovea could contain a repetition of the target (news), a correct preview of the posttarget word (once), an unrelated word (warm), random letters (cxmr), a nonword neighbor of the target (niws), a semantically related word (tale), or a nonword neighbor of that word (tule). Target fixation times were significantly lower in the parafoveal repetition condition than in all other conditions, suggesting that foveal processing can be facilitated by parafoveal repetition. We present a simple model framework that can account for these effects
Dynamical Josephson Effects in NbSe
The study of superconducting materials that also possess nontrivial
correlations or interactions remains an active frontier of condensed matter
physics. NbSe belongs to this class of superconductors and recent research
has focused on the two-dimensional properties of this layered material. Here an
investigation of the superconducting-to-normal-state transition in NbSe is
detailed, and found to be driven by dynamically-created vortices. Under the
application of RF radiation, these vortices allow for two novel Josephson
effects to be observed. The first is a coupling between Josephson currents and
charge density waves in phase-slip junctions. The second is the Josephson
detection of multi-band superconductivity, which is revealed in an anomalous
magnetic field and RF frequency response of the AC Josephson effect. Our
results shed light on the nature of superconductivity in this material,
unearthing exotic phenomena by exploiting nonequilibrium superconducting
effects in atomically-thin materials
Swinging and Tumbling of Fluid Vesicles in Shear Flow
The dynamics of fluid vesicles in simple shear flow is studied using
mesoscale simulations of dynamically-triangulated surfaces, as well as a
theoretical approach based on two variables, a shape parameter and the
inclination angle, which has no adjustable parameters. We show that between the
well-known tank-treading and tumbling states, a new ``swinging'' state can
appear. We predict the dynamic phase diagram as a function of the shear rate,
the viscosities of the membrane and the internal fluid, and the reduced vesicle
volume. Our results agree well with recent experiments.Comment: 4 pages, 4 figure
Fundamental efficiency bound for coherent energy transfer in nanophotonics
We derive a unified quantum theory of coherent and incoherent energy transfer
between two atoms (donor and acceptor) valid in arbitrary Markovian
nanophotonic environments. Our theory predicts a fundamental bound for energy transfer efficiency arising
from the spontaneous emission rates and of the donor
and acceptor. We propose the control of the acceptor spontaneous emission rate
as a new design principle for enhancing energy transfer efficiency. We predict
an experiment using mirrors to enhance the efficiency bound by exploiting the
dipole orientations of the donor and acceptor. Of fundamental interest, we show
that while quantum coherence implies the ultimate efficiency bound has been
reached, reaching the ultimate efficiency does not require quantum coherence.
Our work paves the way towards nanophotonic analogues of efficiency enhancing
environments known in quantum biological systems.Comment: 5 pages, 4 figure
Quantized Rabi Oscillations and Circular Dichroism in Quantum Hall Systems
The dissipative response of a quantum system upon a time-dependent drive can
be exploited as a probe of its geometric and topological properties. In this
work, we explore the implications of such phenomena in the context of
two-dimensional gases subjected to a uniform magnetic field. It is shown that a
filled Landau level exhibits a quantized circular dichroism, which can be
traced back to its underlying non-trivial topology. Based on selection rules,
we find that this quantized circular dichroism can be suitably described in
terms of Rabi oscillations, whose frequencies satisfy simple quantization laws.
Moreover, we discuss how these quantized dissipative responses can be probed
locally, both in the bulk and at the boundaries of the quantum Hall system.
This work suggests alternative forms of topological probes in quantum systems
based on circular dichroism.Comment: 7 pages, including 3 figures and Appendi
Results of bottom trawl surveys carried out in Vietnamese waters (20-200 m) in 1996-1997
Bottom trawl surveys were conducted in the southwest monsoon season in 1996 (survey 1) and in the northeast monsoon season in 1996-97 (survey 2) throughout Vietnamese waters. The surveys mainly covered the depth zone 50-200 m but in the northeast monsoon season the depth zone 20-50 m was included in the northern and southern areas. Overall, 273 trawl hauls were conducted. The total biomass for Vietnamese waters in the depth zone 20-200 m was estimated at 700 000 t . Biomass estimates are given for the most abundant species. A relatively higher mean catch-per-unit effort (CPUE) was obtained from survey 2 than from survey 1 and in partcular at depth ranges 50-100 and 100-200 m in south Vietnam. Overall, the dominant families were Monacanthidae (34%), Carangidae (15%), Trichiuridae (9%) and Synodontidae (6%)
Tracking excited states in wave function optimization using density matrices and variational principles
We present a method for finding individual excited states' energy stationary
points in complete active space self-consistent field theory that is compatible
with standard optimization methods and highly effective at overcoming
difficulties due to root flipping and near-degeneracies. Inspired by both the
maximum overlap method and recent progress in excited state variational
principles, our approach combines these ideas in order to track individual
excited states throughout the orbital optimization process. In a series of
tests involving root flipping, near-degeneracies, charge transfers, and double
excitations, we show that this approach is more effective for state-specific
optimization than either the naive selection of roots based on energy ordering
or a more direct generalization of the maximum overlap method. Furthermore, we
provide evidence that this state-specific approach improves the performance of
complete active space perturbation theory. With a simple implementation, a low
cost, and compatibility with large active space methods, the approach is
designed to be useful in a wide range of excited state investigations.Comment: 13 pages, submitted to JCT
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