185 research outputs found
On holographic three point functions for GKP strings from integrability
Adapting the powerful integrability-based formalism invented previously for
the calculation of gluon scattering amplitudes at strong coupling, we develop a
method for computing the holographic three point functions for the large spin
limit of Gubser-Klebanov- Polyakov (GKP) strings. Although many of the ideas
from the gluon scattering problem can be transplanted with minor modifications,
the fact that the information of the external states is now encoded in the
singularities at the vertex insertion points necessitates several new
techniques. Notably, we develop a new generalized Riemann bilinear identity,
which allows one to express the area integral in terms of appropriate contour
integrals in the presence of such singularities. We also give some general
discussions on how semiclassical vertex operators for heavy string states
should be constructed systematically from the solutions of the Hamilton-Jacobi
equation.Comment: 62 pages;v2 Typos and equation (3.7) corrected. Clarifying remarks
added in Section 4.1. Published version;v3 Minor errors found in version 2
are corrected. For explanation of the revision, see Erratum published in
http://www.springerlink.com/content/m67055235407vx67/?MUD=M
Wave functions and correlation functions for GKP strings from integrability
We develop a general method of computing the contribution of the vertex
operators to the semi-classical correlation functions of heavy string states,
based on the state-operator correspondence and the integrable structure of the
system. Our method requires only the knowledge of the local behavior of the
saddle point configuration around each vertex insertion point and can be
applied to cases where the precise forms of the vertex operators are not known.
As an important application, we compute the contributions of the vertex
operators to the three-point functions of the large spin limit of the
Gubser-Klebanov-Polyakov (GKP) strings in spacetime, left unevaluated
in our previous work [arXiv:1110.3949] which initiated such a study. Combining
with the finite part of the action already computed previously and with the
newly evaluated divergent part of the action, we obtain finite three-point
functions with the expected dependence of the target space boundary coordinates
on the dilatation charge and the spin.Comment: 80 pages, 7 figures, v2: typos and minor errors corrected, a
reference added, v3: typos and a reference corrected, published versio
Adaptively Transforming Graph Matching
Recently, many graph matching methods that incorporate pairwise constraint
and that can be formulated as a quadratic assignment problem (QAP) have been
proposed. Although these methods demonstrate promising results for the graph
matching problem, they have high complexity in space or time. In this paper, we
introduce an adaptively transforming graph matching (ATGM) method from the
perspective of functional representation. More precisely, under a
transformation formulation, we aim to match two graphs by minimizing the
discrepancy between the original graph and the transformed graph. With a linear
representation map of the transformation, the pairwise edge attributes of
graphs are explicitly represented by unary node attributes, which enables us to
reduce the space and time complexity significantly. Due to an efficient
Frank-Wolfe method-based optimization strategy, we can handle graphs with
hundreds and thousands of nodes within an acceptable amount of time. Meanwhile,
because transformation map can preserve graph structures, a domain
adaptation-based strategy is proposed to remove the outliers. The experimental
results demonstrate that our proposed method outperforms the state-of-the-art
graph matching algorithms
Alcohol Consumption Among Older Adults in Primary Care
BACKGROUND: Alcohol misuse is a growing public health concern for older adults, particularly among primary care patients. OBJECTIVES: To determine alcohol consumption patterns and the characteristics associated with at-risk drinking in a large sample of elderly primary care patients. DESIGN: Cross-sectional analysis of multisite screening data from 6 VA Medical Centers, 2 hospital-based health care networks, and 3 Community Health Centers. PARTICIPANTS: Patients, 43,606, aged 65 to 103 years, with scheduled primary care appointments were approached for screening; 27,714 (63.6%) consented to be screened. The final sample of persons with completed screens comprised 24,863 patients. MEASUREMENTS: Quantity and frequency of alcohol use, demographics, social support measures, and measures of depression/anxiety. RESULTS: Of the 24,863 older adults screened, 70.0% reported no consumption of alcohol in the past year, 21.5% were moderate drinkers (1–7 drinks/week), 4.1% were at-risk drinkers (8–14 drinks/week), and 4.5% were heavy (>14 drinks/week) or binge drinkers. Heavy drinking showed significant positive association with depressive/anxiety symptoms [Odds ratio (OR) (95% CI): 1.79 (1.30, 2.45)] and less social support [OR (95% CI): 2.01 (1.14, 2.56)]. Heavy drinking combined with binging was similarly positively associated with depressive/anxiety symptoms [OR (95%): 1.70 (1.33, 2.17)] and perceived poor health [OR (95% CI): 1.27 (1.03, 1.57)], while at-risk drinking was not associated with any of these variables. CONCLUSIONS: The majority of participants were nondrinkers; among alcohol users, at-risk drinkers did not differ significantly from moderate drinkers in their characteristics or for the 3 health parameters evaluated. In contrast, heavy drinking was associated with depression and anxiety and less social support, and heavy drinking combined with binge drinking was associated with depressive/anxiety symptoms and perceived poor health
Emergence of light-driven protometabolism on recruitment of a photocatalytic cofactor by a self-replicator
Establishing how life can emerge from inanimate matter is among the grand challenges of contemporary science. Chemical systems that capture life’s essential characteristics—replication, metabolism and compartmentalization—offer a route to understanding this momentous process. The synthesis of life, whether based on canonical biomolecules or fully synthetic molecules, requires the functional integration of these three characteristics. Here we show how a system of fully synthetic self-replicating molecules, on recruiting a cofactor, acquires the ability to transform thiols in its environment into disulfide precursors from which the molecules can replicate. The binding of replicator and cofactor enhances the activity of the latter in oxidizing thiols into disulfides through photoredox catalysis and thereby accelerates replication by increasing the availability of the disulfide precursors. This positive feedback marks the emergence of light-driven protometabolism in a system that bears no resemblance to canonical biochemistry and constitutes a major step towards the highly challenging aim of creating a new and completely synthetic form of life. [Figure not available: see fulltext.]
Focused Examination of the Intestinal lamina Propria Yields Greater Molecular Insight into Mechanisms Underlying SIV Induced Immune Dysfunction
Background: The Gastrointestinal (GI) tract is critical to AIDS pathogenesis as it is the primary site for viral transmission and a major site of viral replication and CD4 + T cell destruction. Consequently GI disease, a major complication of HIV/SIV infection can facilitate translocation of lumenal bacterial products causing localized/systemic immune activation leading to AIDS progression. Methodology/Principal Findings: To better understand the molecular mechanisms underlying GI disease we analyzed global gene expression profiles sequentially in the intestine of the same animals prior to and at 21 and 90d post SIV infection (PI). More importantly we maximized information gathering by examining distinct mucosal components (intraepithelial lymphocytes, lamina propria leukocytes [LPL], epithelium and fibrovascular stroma) separately. The use of sequential intestinal resections combined with focused examination of distinct mucosal compartments represents novel approaches not previously attempted. Here we report data pertaining to the LPL. A significant increase (61.7-fold) in immune defense/inflammation, cell adhesion/migration, cell signaling, transcription and cell division/differentiation genes were observed at 21 and 90d PI. Genes associated with the JAK-STAT pathway (IL21, IL12R, STAT5A, IL10, SOCS1) and T-cell activation (NFATc1, CDK6, Gelsolin, Moesin) were notably upregulated at 21d PI. Markedly downregulated genes at 21d PI included IL17D/IL27 and IL28B/IFNc3 (anti-HIV/viral), activation induced cytidine deaminase (B-cell function) an
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