3,954 research outputs found
Removing the influence of feature repetitions on the congruency sequence effect: why regressing out confounds from a nested design will often fall short
This article illustrates a shortcoming of using regression to control for confounds in nested designs. As an example, we consider the congruency sequence effect, which is the observation that the congruency effect in distractor interference (e.g., Stroop) tasks is smaller following incongruent as compared with congruent trials. The congruency sequence effect is often interpreted as indexing conflict adaptation: a relative increase of attention to the target following incongruent trials. However, feature repetitions across consecutive trials can complicate this interpretation. To control for this confound, the standard procedure is to delete all trials with a stimulus or response repetition and analyze the remaining trials. Notebaert and Verguts (2007) present an alternative method that allows researchers to use all trials. Specifically, they employ multiple regression to model conflict adaptation independent of feature repetitions. We show here that this approach fails to account for certain feature repetition effects. Furthermore, modeling these additional effects is typically not possible because of an upper bound on the number of degrees of freedom in the experiment. These findings have important implications for future investigations of conflict adaptation and, more broadly, for all researchers who attempt to regress out confounds in nested designs
Controlling Phase Space Caustics in the Semiclassical Coherent State Propagator
The semiclassical formula for the quantum propagator in the coherent state
representation is not
free from the problem of caustics. These are singular points along the complex
classical trajectories specified by , and where
the usual quadratic approximation fails, leading to divergences in the
semiclassical formula. In this paper we derive third order approximations for
this propagator that remain finite in the vicinity of caustics. We use Maslov's
method and the dual representation proposed in Phys. Rev. Lett. {\bf 95},
050405 (2005) to derive uniform, regular and transitional semiclassical
approximations for coherent state propagator in systems with two degrees of
freedom.Comment: 24 pages, to appear in Ann. of Phy
Functional kernel estimators of conditional extreme quantiles
We address the estimation of "extreme" conditional quantiles i.e. when their
order converges to one as the sample size increases. Conditions on the rate of
convergence of their order to one are provided to obtain asymptotically
Gaussian distributed kernel estimators. A Weissman-type estimator and kernel
estimators of the conditional tail-index are derived, permitting to estimate
extreme conditional quantiles of arbitrary order.Comment: arXiv admin note: text overlap with arXiv:1107.226
Construction and purpose of effective field theories for frustrated magnetic order
This article reviews recent years' progress in the low temperature analysis
of standard models of spin glass order such as the Sherrington-Kirkpatrick (SK)
model. Applications to CdTe/CdMnTe layered systems and explanation of glassy
antiferromagnetic order at lowest temperatures stimulated us to study in detail
the beautifully complex physical effects of replica symmetry breaking (RSB).We
discuss analytical ideas based on highly precise numerical data which lead to
the construction of relatively simple effective field theories for the SK model
and help to understand the mysterious features of its exact solution. The goal
is to find construction principles for the theory of interplay between
frustrated magnetic order and various relevant physical degrees of freedom. The
emphasis in this article is on the role of Parisi's RSB, which surprisingly
creates critical phenomena in the low temperature limit despite the absence of
a standard phase transition.Comment: Published online in Physica Status Solidi C (June 4 2007
A Model of the Cellular Iron Homeostasis Network Using Semi-Formal Methods for Parameter Space Exploration
This paper presents a novel framework for the modeling of biological
networks. It makes use of recent tools analyzing the robust satisfaction of
properties of (hybrid) dynamical systems. The main challenge of this approach
as applied to biological systems is to get access to the relevant parameter
sets despite gaps in the available knowledge. An initial estimate of useful
parameters was sought by formalizing the known behavior of the biological
network in the STL logic using the tool Breach. Then, once a set of parameter
values consistent with known biological properties was found, we tried to
locally expand it into the largest possible valid region. We applied this
methodology in an effort to model and better understand the complex network
regulating iron homeostasis in mammalian cells. This system plays an important
role in many biological functions, including erythropoiesis, resistance against
infections, and proliferation of cancer cells.Comment: In Proceedings HSB 2012, arXiv:1208.315
Semiclassical coherent state propagator for systems with spin
We derive the semiclassical limit of the coherent state propagator for
systems with two degrees of freedom of which one degree of freedom is canonical
and the other a spin. Systems in this category include those involving
spin-orbit interactions and the Jaynes-Cummings model in which a single
electromagnetic mode interacts with many independent two-level atoms. We
construct a path integral representation for the propagator of such systems and
derive its semiclassical limit. As special cases we consider separable systems,
the limit of very large spins and the case of spin 1/2.Comment: 19 pages, no figure
A Bima Array Survey of Molecules in Comets Linear (C/2002 T7) and Neat (C/2001 Q4)
We present an interferometric search for large molecules, including methanol,
methyl cyanide, ethyl cyanide, ethanol, and methyl formate in comets LINEAR
(C/2002 T7) and NEAT (C/2001 Q4) with the Berkeley-Illinois-Maryland
Association (BIMA) array. In addition, we also searched for transitions of the
simpler molecules CS, SiO, HNC, HN13C and 13CO . We detected transitions of
methanol and CS around Comet LINEAR and one transition of methanol around Comet
NEAT within a synthesized beam of ~20''. We calculated the total column density
and production rate of each molecular species using the variable temperature
and outflow velocity (VTOV) model described by Friedel et al.(2005).Considering
the molecular production rate ratios with respect to water, Comet T7 LINEAR is
more similar to Comet Hale-Bopp while Comet Q4 NEAT is more similar to Comet
Hyakutake. It is unclear, however, due to such a small sample size, whether
there is a clear distinction between a Hale-Bopp and Hyakutake class of comet
or whether comets have a continuous range of molecular production rate ratios.Comment: Accepted for Publication in the Astrophysical Journa
A Brief Report: Lessons Learned and Preliminary Findings of Progreso en Salud, an HIV Risk Reduction Intervention for Latina Seasonal Farmworkers
Throughout the past decade, HIV rates in Florida?particularly South Florida, where many Latina seasonal farmworkers reside and work?have ranked among the highest in the nation. In this brief report, we delineate important lessons learned and preliminary findings from the implementation of the HIV prevention intervention Progreso en Salud (Progress in Health). Among the 114 Latina seasonal farmworker participants, there were significant increases from baseline to 6-month follow-up in the percentages of overall condom use, HIV testing, HIV/AIDS-related communications with friends, HIV knowledge, condom use self-efficacy, and correct use of condoms. Lessons learned from this study can be used to inform future HIV intervention strategies to improve the adoption and maintenance of HIV risk reduction behaviors among high-risk Latina seasonal workers and other high-risk underserved populations. Future research is needed to support our findings
beta-decay study of Cu-77
A beta-decay study of Cu-77 has been performed at the ISOLDE mass separator
with the aim to deduce its beta-decay properties and to obtain spectroscopic
information on Zn-77. Neutron-rich copper isotopes were produced by means of
proton- or neutron-induced fission reactions on U-238. After the production,
Cu-77 was selectively laser ionized, mass separated and sent to different
detection systems where beta-gamma and beta-n coincidence data were collected.
We report on the deduced half-live, decay scheme, and possible spin assignment
of 77Cu
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