1,504 research outputs found

    On Classical Equivalence Between Noncritical and Einstein Gravity : The AdS/CFT Perspectives

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    We find that noncritical gravity, a special class of higher derivative gravity, is classically equivalent to Einstein gravity at the full nonlinear level. We obtain the viscosity-to-entropy ratio and the second order transport coefficients of the dual fluid of noncritical gravity to all orders in the coupling of higher derivative terms. We also compute the holographic entanglement entropy in the dual CFT of noncritical gravity. All these results confirm the nonlinear equivalence between noncritical gravity and Einstein gravity at the classical level.Comment: 19 pages, no figure

    Navigation of Distinct Euclidean Particles via Hierarchical Clustering

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    We present a centralized online (completely reactive) hybrid navigation algorithm for bringing a swarm of n perfectly sensed and actuated point particles in Euclidean d space (for arbitrary n and d) to an arbitrary goal configuration with the guarantee of no collisions along the way. Our construction entails a discrete abstraction of configurations using cluster hierarchies, and relies upon two prior recent constructions: (i) a family of hierarchy-preserving control policies and (ii) an abstract discrete dynamical system for navigating through the space of cluster hierarchies. Here, we relate the (combinatorial) topology of hierarchical clusters to the (continuous) topology of configurations by constructing “portals” — open sets of configurations supporting two adjacent hierarchies. The resulting online sequential composition of hierarchy-invariant swarming followed by discrete selection of a hierarchy “closer” to that of the destination along with its continuous instantiation via an appropriate portal configuration yields a computationally effective construction for the desired navigation policy

    Compact High-Velocity Clouds at High Resolution

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    Six examples of the compact, isolated high-velocity clouds catalogued by Braun & Burton (1999) and identified with a dynamically cold ensemble of primitive objects falling towards the barycenter of the Local Group have been imaged with the Westerbork Synthesis Radio Telescope; an additional ten have been imaged with the Arecibo telescope. The imaging reveals a characteristic core/halo morphology: one or several cores of cool, relatively high-column-density material, are embedded in an extended halo of warmer, lower-density material. Several of the cores show kinematic gradients consistent with rotation; these CHVCs are evidently rotationally supported and dark-matter dominated. The imaging data allows several independent estimates of the distances to these objects, which lie in the range 0.3 to 1.0 Mpc. The CHVC properties resemble what might be expected from very dark dwarf irregular galaxies.Comment: 12 pages, 7 figures, to appear in "The Chemical Evolution of the Milky Way: Stars versus Clusters", eds. F. Matteuchi and F. Giovannelli, Kluwer Academic Publisher

    Genus-one correction to asymptotically free Seiberg-Witten prepotential from Dijkgraaf-Vafa matrix model

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    We find perfect agreements on the genus-one correction to the prepotential of SU(2) Seiberg-Witten theory with N_f=2, 3 between field theoretical and Dijkgraaf-Vafa-Penner type matrix model results.Comment: 12 pages; v2: minor revision; v3: more structured, submitted versio

    Classical conformal blocks from TBA for the elliptic Calogero-Moser system

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    The so-called Poghossian identities connecting the toric and spherical blocks, the AGT relation on the torus and the Nekrasov-Shatashvili formula for the elliptic Calogero-Moser Yang's (eCMY) functional are used to derive certain expressions for the classical 4-point block on the sphere. The main motivation for this line of research is the longstanding open problem of uniformization of the 4-punctured Riemann sphere, where the 4-point classical block plays a crucial role. It is found that the obtained representation for certain 4-point classical blocks implies the relation between the accessory parameter of the Fuchsian uniformization of the 4-punctured sphere and the eCMY functional. Additionally, a relation between the 4-point classical block and the Nf=4N_f=4, SU(2){\sf SU(2)} twisted superpotential is found and further used to re-derive the instanton sector of the Seiberg-Witten prepotential of the Nf=4N_f=4, SU(2){\sf SU(2)} supersymmetric gauge theory from the classical block.Comment: 25 pages, no figures, latex+JHEP3, published versio

    The contribution of embarrassment to phobic dental anxiety: a qualitative research study

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    BACKGROUND: Embarrassment is emphasized, yet scantily described as a factor in extreme dental anxiety or phobia. Present study aimed to describe details of social aspects of anxiety in dental situations, especially focusing on embarrassment phenomena. METHODS: Subjects (Ss) were consecutive specialist clinic patients, 16 men, 14 women, 20–65 yr, who avoided treatment mean 12.7 yr due to anxiety. Electronic patient records and transcribed initial assessment and exit interviews were analyzed using QSR"N4" software to aid in exploring contexts related to social aspects of dental anxiety and embarrassment phenomena. Qualitative findings were co-validated with tests of association between embarrassment intensity ratings, years of treatment avoidance, and mouth-hiding behavioral ratings. RESULTS: Embarrassment was a complaint in all but three cases. Chief complaints in the sample: 30% had fear of pain; 47% cited powerlessness in relation to dental social situations, some specific to embarrassment and 23% named co-morbid psychosocial dysfunction due to effects of sexual abuse, general anxiety, gagging, fainting or panic attacks. Intense embarrassment was manifested in both clinical and non-clinical situations due to poor dental status or perceived neglect, often (n = 9) with fear of negative social evaluation as chief complaint. These nine cases were qualitatively different from other cases with chief complaints of social powerlessness associated with conditioned distrust of dentists and their negative behaviors. The majority of embarrassed Ss to some degree inhibited smiling/laughing by hiding with lips, hands or changed head position. Secrecy, taboo-thinking, and mouth-hiding were associated with intense embarrassment. Especially after many years of avoidance, embarrassment phenomena lead to feelings of self-punishment, poor self-image/esteem and in some cases personality changes in a vicious circle of anxiety and avoidance. Embarrassment intensity ratings were positively correlated with years of avoidance and degree of mouth-hiding behaviors. CONCLUSIONS: Embarrassment is a complex dental anxiety manifestation with qualitative differences by complaint characteristics and perceived intensity. Some cases exhibited manifestations similar to psychiatric criteria for social anxiety disorder as chief complaint, while most manifested embarrassment as a side effect

    Multi-level evidence of an allelic hierarchy of USH2A variants in hearing, auditory processing and speech/language outcomes.

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    Language development builds upon a complex network of interacting subservient systems. It therefore follows that variations in, and subclinical disruptions of, these systems may have secondary effects on emergent language. In this paper, we consider the relationship between genetic variants, hearing, auditory processing and language development. We employ whole genome sequencing in a discovery family to target association and gene x environment interaction analyses in two large population cohorts; the Avon Longitudinal Study of Parents and Children (ALSPAC) and UK10K. These investigations indicate that USH2A variants are associated with altered low-frequency sound perception which, in turn, increases the risk of developmental language disorder. We further show that Ush2a heterozygote mice have low-level hearing impairments, persistent higher-order acoustic processing deficits and altered vocalizations. These findings provide new insights into the complexity of genetic mechanisms serving language development and disorders and the relationships between developmental auditory and neural systems

    Heritability of non-speech auditory processing skills

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    Recent insight into the genetic bases for autism spectrum disorder, dyslexia, stuttering, and language disorders suggest that neurogenetic approaches may also reveal at least one etiology of auditory processing disorder (APD). A person with an APD typically has difficulty understanding speech in background noise despite having normal pure-tone hearing sensitivity. The estimated prevalence of APD may be as high as 10% in the pediatric population, yet the causes are unknown and have not been explored by molecular or genetic approaches. The aim of our study was to determine the heritability of frequency and temporal resolution for auditory signals and speech recognition in noise in 96 identical or fraternal twin pairs, aged 6–11 years. Measures of auditory processing (AP) of non-speech sounds included backward masking (temporal resolution), notched noise masking (spectral resolution), pure-tone frequency discrimination (temporal fine structure sensitivity), and nonsense syllable recognition in noise. We provide evidence of significant heritability, ranging from 0.32 to 0.74, for individual measures of these non-speech-based AP skills that are crucial for understanding spoken language. Identification of specific heritable AP traits such as these serve as a basis to pursue the genetic underpinnings of APD by identifying genetic variants associated with common AP disorders in children and adults

    The matrix model version of AGT conjecture and CIV-DV prepotential

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    Recently exact formulas were provided for partition function of conformal (multi-Penner) beta-ensemble in the Dijkgraaf-Vafa phase, which, if interpreted as Dotsenko-Fateev correlator of screenings and analytically continued in the number of screening insertions, represents generic Virasoro conformal blocks. Actually these formulas describe the lowest terms of the q_a-expansion, where q_a parameterize the shape of the Penner potential, and are exact in the filling numbers N_a. At the same time, the older theory of CIV-DV prepotential, straightforwardly extended to arbitrary beta and to non-polynomial potentials, provides an alternative expansion: in powers of N_a and exact in q_a. We check that the two expansions coincide in the overlapping region, i.e. for the lowest terms of expansions in both q_a and N_a. This coincidence is somewhat non-trivial, since the two methods use different integration contours: integrals in one case are of the B-function (Euler-Selberg) type, while in the other case they are Gaussian integrals.Comment: 27 pages, 1 figur
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