669 research outputs found
A matrix model for a quantum hall droplet with manifest particle-hole symmetry
We find that a gauged matrix model of rectangular fermionic matrices (a
matrix version of the fermion harmonic oscillator) realizes a quantum hall
droplet with manifest particle-hole symmetry. The droplet consists of free
fermions on the topology of a sphere. It is also possible to deform the
Hamiltonian by double trace operators, and we argue that this device can
produce two body potentials which might lead the system to realize a fractional
quantum hall state on the sphere. We also argue that a single gauged fermionic
quantum mechanics of hermitian matrices realizes a droplet with an edge that
has CFT on it.Comment: 25 pages, uses JHEP format, young.sty (included). v2: Updated
references, typos correcte
Einstein-Hilbert action on the brane for the bulk graviton
We find new closed string couplings on Dp-branes for the bosonic string.
These couplings are quadratic in derivatives and therefore take the form of
induced kinetic terms on the brane. For the graviton in particular we find the
induced Einstein-Hilbert term as well as terms quadratic in the second
fundamental tensor. We comment on tachyon dependences of these brane-localized
couplings.Comment: 21 pages, 4 figures, JHEP style, discussion on field redefinitions
expanded and references adde
A study of the relationship between secondary teacher satisfaction and attitude toward collective negotiations
Aspects of emergent geometry in the AdS/CFT context
We study aspects of emergent geometry for the case of orbifold superconformal
field theories in four dimensions, where the orbifolds are abelian within the
AdS/CFT proposal. In particular, we show that the realization of emergent
geometry starting from the N=4 SYM theory in terms of a gas of particles in the
moduli space of vacua of a single D3 brane in flat space gets generalized to a
gas of particles on the moduli space of the corresponding orbifold conformal
field theory (a gas of D3 branes on the orbifold space). Our main purpose is to
show that this can be analyzed using the same techniques as in the N=4 SYM case
by using the method of images, including the measure effects associated to the
volume of the gauge orbit of the configurations. This measure effect gives an
effective repulsion between the particles that makes them condense into a
non-trivial vacuum configuration, and it is exactly these configurations that
lead to the geometry of X in the AdS x X dual field theoryComment: 24 page
Not all disfluencies are are equal: The effects of disfluent repetitions on language comprehension
Disfluencies can affect language comprehension, but to date, most studies have focused on disfluent pauses such as er. We investigated whether disfluent repetitions in speech have discernible effects on listeners during language comprehension, and whether repetitions affect the linguistic processing of subsequent words in speech in ways which have been previously observed with ers. We used event-related potentials (ERPs) to measure participantsâ neural responses to disfluent repetitions of words relative to acoustically identical words in fluent contexts, as well as to unpredictable and predictable words that occurred immediately post-disfluency and in fluent utterances. We additionally measured participantsâ recognition memories for the predictable and unpredictable words. Repetitions elicited an early onsetting relative positivity (100â400 ms post-stimulus), clearly demonstrating listenersâ sensitivity to the presence of disfluent repetitions. Unpredictable words elicited an N400 effect. Importantly, there was no evidence that this effect, thought to reflect the difficulty of semantically integrating unpredictable compared to predictable words, differed quantitatively between fluent and disfluent utterances. Furthermore there was no evidence that the memorability of words was affected by the presence of a preceding repetition. These findings contrast with previous research which demonstrated an N400 attenuation of, and an increase in memorability for, words that were preceded by an er. However, in a later (600â900 ms) time window, unpredictable words following a repetition elicited a relative positivity. Reanalysis of previous data confirmed the presence of a similar effect following an er. The effect may reflect difficulties in resuming linguistic processing following any disruption to speech
Quantizing Open Spin Chains with Variable Length: an example from Giant Gravitons
We study an XXX open spin chain with variable number of sites, where the
variability is introduced only at the boundaries. This model arises naturally
in the study of Giant Gravitons in the AdS/CFT correspondence. We show how to
quantize the spin chain by mapping its states to a bosonic lattice of finite
length with sources and sinks of particles at the boundaries. Using coherent
states, we show how the Hamiltonian for the bosonic lattice gives the correct
description of semiclassical open strings ending on Giant Gravitons.Comment: 4 pages. v2: updated reference
Itâs the way that you, er, say it: hesitations in speech affect language comprehension
Everyday speech is littered with disfluency, often correlated with the production of less predictable words (e.g., Beattie & Butterworth [Beattie, G., & Butterworth, B. (1979). Contextual probability and word frequency as determinants of pauses in spontaneous speech. Language and Speech, 22, 201â211.]). But what are the effects of disfluency on listeners? In an ERP experiment which compared fluent to disfluent utterances, we established an N400 effect for unpredictable compared to predictable words. This effect, reflecting the difference in ease of integrating words into their contexts, was reduced in cases where the target words were preceded by a hesitation marked by the word er. Moreover, a subsequent recognition memory test showed that words preceded by disfluency were more likely to be remembered. The study demonstrates that hesitation affects the way in which listeners process spoken language, and that these changes are associated with longer-term consequences for the representation of the message
Probing the Enhancon via Calculations in Supersymmetric Gauge Theory
We consider the N=2 gauge theory on N D7-branes wrapping K3, with D3-brane
probes. In the large N limit, the D7-branes blow up to form an enhancon shell.
We probe the region inside and outside the enhancon shell using the D3-branes,
and compute the probe metric using the Seiberg-Witten formalism. Supergravity
arguments suggest a flat interior up to 1/N corrections, and indeed our results
for the D3-brane probes are consistent with that. By including the dynamics of
the branes, these results, together with those of hep-th/0204050, demonstrate
the robustness of the enhancon mechanism beyond patching together of
supergravity solutions with D-brane source junction conditions.Comment: 20 pages, 2 figures, minor correction
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Social Network Simulation and Mining Social Media to Advance Epidemiology
Traditional Public Health decision-support can benefit from the Web and social media revolution. This dissertation presents approaches to mining social media benefiting public health epidemiology. Through discovery and analysis of trends in Influenza related blogs, a correlation to Centers for Disease Control and Prevention (CDC) influenza-like-illness patient reporting at sentinel health-care providers is verified. A second approach considers personal beliefs of vaccination in social media. A vaccine for human papillomavirus (HPV) was approved by the Food and Drug Administration in May 2006. The virus is present in nearly all cervical cancers and implicated in many throat and oral cancers. Results from automatic sentiment classification of HPV vaccination beliefs are presented which will enable more accurate prediction of the vaccine's population-level impact. Two epidemic models are introduced that embody the intimate social networks related to HPV transmission. Ultimately, aggregating these methodologies with epidemic and social network modeling facilitate effective development of strategies for targeted interventions
Attention orienting effects of hesitations in speech: evidence from ERPs
Filled-pause disfluencies such as um and er affect listenersâ comprehension, possibly mediated by attentional mechanisms (J. E. Fox Tree, 2001). However, there is little direct evidence that hesitations affect attention. The current study used an coustic manipulation of continuous speech to induce event-related potential components associated with attention (mismatch negativity [MMN] and P300) during the comprehension of fluent and disfluent utterances. In fluent cases, infrequently occurring acoustically manipulated target words gave rise to typical MMN and P300 components when compared to nonmanipulated controls. In disfluent cases, where targets were preceded by natural sounding hesitations culminating in the filled pause er, an MMN (reflecting a detection of deviance) was still apparent for manipulated words, but there was little evidence of a subsequent P300. This suggests that attention was not reoriented to deviant words in disfluent cases. A subsequent recognition test showed that nonmanipulated words were more likely to be remembered if they had been preceded by a hesitation. Taken together, these results strongly implicate attention in an account of disfluency processing: Hesitations orient listenersâ attention, with consequences for the immediate processing and later representation of an utterance
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