Turbulence and Chaos in Anti-de-Sitter Gravity

Due to the AdS/CFT correspondence the question of instability of Anti-de-Sitter spacetimes sits in the intersection of mathematical and numerical relativity, string theory, field theory and condensed matter physics. In this essay we revisit that important question emphasizing the power of spectral methods and highlighting the effectiveness of standard techniques for studying nonlinear dynamical systems. In particular we display explicitly how the problem can be modeled as a system on nonlinearly coupled harmonic oscillators. We highlight some of the many open questions that stem from this result and point out that a full understanding will necessarily required the interdisciplinary cooperation of various communities.Comment: 6 pages, 12 figures. Essay awarded honorable mention in the Gravity Research Foundation essay competition 201

Electrostatic Tuning of the Superconductor-Insulator Transition in Two Dimensions

Superconductivity has been induced in insulating ultra-thin films of amorphous bismuth using the electric field effect. The screening of electron-electron interaction was found to increase with electron concentration in a manner correlated with the tendency towards superconductivity. This does not preclude an increase in the density of states being important in the development of superconductivity. The superconductor-insulator transition appears to belong to the universality class of the three dimensional XY model.Comment: Four pages, three figures. Revised slightly to reflect referees' comment

Tensions and Luscher Terms for (2+1)-dimensional k-strings from Holographic Models

The leading term for the energy of a bound state of k-quarks and k-antiquarks is proportional to its separation L. These k-string configurations have a Luscher term associated with their quantum fluctuations which is typically a 1/L correction to the energy. We review the status of tensions and Luscher terms in the context of lattice gauge theory, Hamiltonian methods, and gauge/gravity correspondence. Furthermore we explore how different representations of the k-string manifest themselves in the gauge/gravity duality. We calculate the Luscher term for a strongly coupled SU(N) gauge theory in (2+1) dimensions using the gauge/gravity correspondence. Namely, we compute one-loop corrections to a probe D4-brane embedded in the Cvetic, Gibbons, Lu, and Pope supergravity background. We investigate quantum fluctuations of both the bosonic and the fermionic sectors.Comment: 39 pages, reference added, same version to be published in JHE

A Kolmogorov-Zakharov Spectrum in AdSAdS Gravitational Collapse

We study black hole formation during the gravitational collapse of a massless scalar field in asymptotically $AdS_D$ spacetimes for $D=4,5$. We conclude that spherically symmetric gravitational collapse in asymptotically $AdS$ spaces is turbulent and characterized by a Kolmogorov-Zakharov spectrum. Namely, we find that after an initial period of weakly nonlinear evolution, there is a regime where the power spectrum of the Ricci scalar evolves as $\omega^{-s}$ with the frequency, $\omega$, and $s\approx 1.7\pm 0.1$.Comment: 5 pages, 4 figures. v2: Typos, other initial profile considered for universality, error analysis, close to PRL versio

Beyond AdS2_2/dCFT1_1: Insertions in Two Wilson Loops

We consider two-point correlators of local operator insertions in a system of two Wilson-Maldacena loops in ${\cal N}=4$ supersymmetric Yang-Mills theory on both sides of the AdS/CFT correspondence. On the holographic side the correlator of two Wilson-Maldacena loops is given by a classical string world-sheet which in one phase connects two asymptotically AdS$_2$ regions and in the other phase is given by two disconnected AdS$_2$ caps; this configuration breaks supersymmetry as well as conformal invariance. We present a complete systematic account of the string world-sheet fluctuations, including the fermionic sector, and study the behavior of the holographic two-point correlators. On the field theory side we compute certain two-point correlators of local operator insertions by resumming sets of ladder diagrams. Our results demonstrate the efficacy of previously developed methods in tackling this non-conformal, non-susy regime

Current Challenges and Applications for Adaptive User Interfaces

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Means, Intent, Lethality, Behaviors, and Psychiatric Diagnosis in Latina Adolescent Suicide Attempters

This article describes the means, intent, lethality, behavioral profiles, and psychiatric diagnoses of adolescent Latina suicide attempters. From a large, mixed-method project studying the sociocultural processes of Latina suicide attempts, we selected 76 participants for this report. In addition to quantitative research data, medical records were available for all 76 participants, as was qualitative data from in-depth interviews for 34 of them. Using the qualitative and quantitative research data, we explored intent and behavioral profiles of the suicidal adolescents. Medical records provided additional information about the means the adolescents used in their attempts, and about their psychiatric diagnoses. The lethality of suicide attempts was coded using the Lethality of Suicide Attempt Rating Scale (LSARS) and the Lethality of Suicide Attempt Rating Scale—Updated (LSARS-II). Findings showed that Latina adolescent suicide attempts are low in lethality. Consistent with the literature, most adolescents reported that they attempted by using means available in their homes (cutting and overdosing with medications were the predominant methods). Interesting discrepancies emerged when comparing adolescents’ self-reported behavioral profiles with clinicians’ psychiatric diagnoses. This report has implications for diagnosis and treatment approaches for both inpatient and outpatient service providers

Gauged (2,2) Sigma Models and Generalized Kahler Geometry

We gauge the (2,2) supersymmetric non-linear sigma model whose target space has bihermitian structure (g, B, J_{\pm}) with noncommuting complex structures. The bihermitian geometry is realized by a sigma model which is written in terms of (2,2) semi-chiral superfields. We discuss the moment map, from the perspective of the gauged sigma model action and from the integrability condition for a Hamiltonian vector field. We show that for a concrete example, the SU(2) x U(1) WZNW model, as well as for the sigma models with almost product structure, the moment map can be used together with the corresponding Killing vector to form an element of T+T* which lies in the eigenbundle of the generalized almost complex structure. Lastly, we discuss T-duality at the level of a (2,2) sigma model involving semi-chiral superfields and present an explicit example.Comment: 33 page

Comments on supergravity dual of pure N=1 Super Yang Mills theory with unbroken chiral symmetry

Maldacena and Nunez [hep-th/0008001] identified a gravity solution describing pure N=1 Yang-Mills (YM) in the IR. Their (smooth) supergravity solution exhibits confinement and the U(1)_R chiral symmetry breaking of the dual YM theory, while the singular solution corresponds to the gauge theory phase with unbroken U(1)_R chiral symmetry. In this paper we discuss supersymmetric type IIB compactifications on resolved conifolds with torsion. We rederive singular background of [hep-th/0008001] directly from the supersymmetry conditions. This solution is the relevant starting point to study non-BPS backgrounds dual to the high temperature phase of pure YM. We construct the simplest black hole solution in this background. We argue that it has a regular Schwarzschild horizon and provides a resolution of the IR singularity of the chirally symmetric extremal solution as suggested in [hep-th/0011146].Comment: 34 pages, LaTeX, v2: references added, v3: section 2 reduced, minor clarifications, to be published in PR

Familism and family environment among suicidal Latinas: Three family types

This study examined the relationship between familism and family environment type as well as the relationship between family environment type and suicide attempts among Latina youth. Latina teen attempters (n=109) and non-attempters (n=107) were recruited from the NYC area. Latent class analysis revealed three family environment types: tight-knit; intermediate-knit; and loose-knit. Tight-knit families (high cohesion and low conflict) were significantly less likely to have teens that attempted suicide as compared to intermediate-knit families or loose-knit families. Moreover, familism increased the odds of being in the tight-knit family vs. the loose-knit family and the odds of being in the tight-knit family vs. the intermediate-knit. Results suggest that familism may protect against suicide behavior among Latinas via its influence on family environment