8,900 research outputs found
Permutation Orbifolds and Chaos
We study out-of-time-ordered correlation functions in permutation orbifolds
at large central charge. We show that they do not decay at late times for
arbitrary choices of low-dimension operators, indicating that permutation
orbifolds are non-chaotic theories. This is in agreement with the fact they are
free discrete gauge theories and should be integrable rather than chaotic. We
comment on the early-time behaviour of the correlators as well as the
deformation to strong coupling.Comment: 15 pages, v2: more references and additional comments in the
introductio
Similarities in face and voice cerebral processing
In this short paper I illustrate by a few selected examples several compelling similarities in the functional organization of face and voice cerebral processing: (1) Presence of cortical areas selective to face or voice stimuli, also observed in non-human primates, and causally related to perception; (2) Coding of face or voice identity using a “norm-based” scheme; (3) Personality inferences from faces and voices in a same Trustworthiness–Dominance “social space”
A unified coding strategy for processing faces and voices
Both faces and voices are rich in socially-relevant information, which humans are remarkably adept at extracting, including a person's identity, age, gender, affective state, personality, etc. Here, we review accumulating evidence from behavioral, neuropsychological, electrophysiological, and neuroimaging studies which suggest that the cognitive and neural processing mechanisms engaged by perceiving faces or voices are highly similar, despite the very different nature of their sensory input. The similarity between the two mechanisms likely facilitates the multi-modal integration of facial and vocal information during everyday social interactions. These findings emphasize a parsimonious principle of cerebral organization, where similar computational problems in different modalities are solved using similar solutions
Gender differences in the temporal voice areas
There is not only evidence for behavioral differences in voice perception between female and male listeners, but also recent suggestions for differences in neural correlates between genders. The fMRI functional voice localizer (comprising a univariate analysis contrasting stimulation with vocal versus non-vocal sounds) is known to give robust estimates of the temporal voice areas (TVAs). However there is growing interest in employing multivariate analysis approaches to fMRI data (e.g. multivariate pattern analysis; MVPA). The aim of the current study was to localize voice-related areas in both female and male listeners and to investigate whether brain maps may differ depending on the gender of the listener. After a univariate analysis, a random effects analysis was performed on female (n = 149) and male (n = 123) listeners and contrasts between them were computed. In addition, MVPA with a whole-brain searchlight approach was implemented and classification maps were entered into a second-level permutation based random effects models using statistical non-parametric mapping (SnPM; Nichols & Holmes 2002). Gender differences were found only in the MVPA. Identified regions were located in the middle part of the middle temporal gyrus (bilateral) and the middle superior temporal gyrus (right hemisphere). Our results suggest differences in classifier performance between genders in response to the voice localizer with higher classification accuracy from local BOLD signal patterns in several temporal-lobe regions in female listeners
Thermal conductivity in the vortex state of d-wave superconductors
We present the results of a microscopic calculation of the longitudinal
thermal conductivity of quasiparticles, , in a 2D d-wave
superconductor in the vortex state. Our approach takes into account both
impurity scattering and a contribution to the thermal transport lifetime due to
the scattering of quasiparticles off of vortices. We compare the results with
the experimental measurements on high-T cuprates and organic
superconductors.Comment: 2 pages, submitted to proceedings of M2S-HTSC-VI (Houston
The potential for bias in principal causal effect estimation when treatment received depends on a key covariate
Motivated by a potential-outcomes perspective, the idea of principal
stratification has been widely recognized for its relevance in settings
susceptible to posttreatment selection bias such as randomized clinical trials
where treatment received can differ from treatment assigned. In one such
setting, we address subtleties involved in inference for causal effects when
using a key covariate to predict membership in latent principal strata. We show
that when treatment received can differ from treatment assigned in both study
arms, incorporating a stratum-predictive covariate can make estimates of the
"complier average causal effect" (CACE) derive from observations in the two
treatment arms with different covariate distributions. Adopting a Bayesian
perspective and using Markov chain Monte Carlo for computation, we develop
posterior checks that characterize the extent to which incorporating the
pretreatment covariate endangers estimation of the CACE. We apply the method to
analyze a clinical trial comparing two treatments for jaw fractures in which
the study protocol allowed surgeons to overrule both possible randomized
treatment assignments based on their clinical judgment and the data contained a
key covariate (injury severity) predictive of treatment received.Comment: Published in at http://dx.doi.org/10.1214/11-AOAS477 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
The sound of trustworthiness: acoustic-based modulation of perceived voice personality
When we hear a new voice we automatically form a "first impression" of the voice owner’s
personality; a single word is sufficient to yield ratings highly consistent across listeners. Past
studies have shown correlations between personality ratings and acoustical parameters of
voice, suggesting a potential acoustical basis for voice personality impressions, but its
nature and extent remain unclear. Here we used data-driven voice computational modelling
to investigate the link between acoustics and perceived trustworthiness in the single word
"hello". Two prototypical voice stimuli were generated based on the acoustical features of
voices rated low or high in perceived trustworthiness, respectively, as well as a continuum
of stimuli inter- and extrapolated between these two prototypes. Five hundred listeners
provided trustworthiness ratings on the stimuli via an online interface. We observed an
extremely tight relationship between trustworthiness ratings and position along the trustworthiness
continuum (r = 0.99). Not only were trustworthiness ratings higher for the high- than
the low-prototypes, but the difference could be modulated quasi-linearly by reducing or
exaggerating the acoustical difference between the prototypes, resulting in a strong
caricaturing effect. The f0 trajectory, or intonation, appeared a parameter of particular relevance:
hellos rated high in trustworthiness were characterized by a high starting f0 then a
marked decrease at mid-utterance to finish on a strong rise. These results demonstrate a
strong acoustical basis for voice personality impressions, opening the door to multiple
potential applications
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