1,952 research outputs found

    Baryonic Generating Functions

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    We show how it is possible to use the plethystic program in order to compute baryonic generating functions that count BPS operators in the chiral ring of quiver gauge theories living on the world volume of D branes probing a non compact CY manifold. Special attention is given to the conifold theory and the orbifold C^2/Z_2 times C, where exact expressions for generating functions are given in detail. This paper solves a long standing problem for the combinatorics of quiver gauge theories with baryonic moduli spaces. It opens the way to a statistical analysis of quiver theories on baryonic branches. Surprisingly, the baryonic charge turns out to be the quantized Kahler modulus of the geometry.Comment: 44 pages, 7 figures; fonts change

    QCD and String Theory

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    This talk begins with some history and basic facts about string theory and its connections with strong interactions. Comparisons of stacks of Dirichlet branes with curved backgrounds produced by them are used to motivate the AdS/CFT correspondence between superconformal gauge theory and string theory on a product of Anti-de Sitter space and a compact manifold. The ensuing duality between semi-classical spinning strings and long gauge theory operators is briefly reviewed. Strongly coupled thermal SYM theory is explored via a black hole in 5-dimensional AdS space, which leads to explicit results for its entropy and shear viscosity. A conjectured universal lower bound on the viscosity to entropy density ratio, and its possible relation to recent results from RHIC, are discussed. Finally, some available results on string duals of confining gauge theories are briefly reviewed.Comment: 12 pages, prepared for the Proceedings of the 2005 Lepton-Photon Symposium; v2: minor revisions, references added, the version to appear in the proceeding

    Deformations of conformal theories and non-toric quiver gauge theories

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    We discuss several examples of non-toric quiver gauge theories dual to Sasaki-Einstein manifolds with U(1)^2 or U(1) isometry. We give a general method for constructing non-toric examples by adding relevant deformations to the toric case. For all examples, we are able to make a complete comparison between the prediction for R-charges based on geometry and on quantum field theory. We also give a general discussion of the spectrum of conformal dimensions for mesonic and baryonic operators for a generic quiver theory; in the toric case we make an explicit comparison between R-charges of mesons and baryons.Comment: 51 pages, 12 figures; minor corrections in appendix B, published versio

    Early brain damage affects body schema and person perception abilities in children and adolescents with spastic diplegia

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    Early brain damage leading to cerebral palsy is associated to core motor impairments and also affects cognitive and social abilities. In particular, previous studies have documented specific alterations of perceptual body processing and motor cognition that are associated to unilateral motor deficits in hemiplegic patients. However, little is known about spastic diplegia (SpD), which is characterized by motorial deficits involving both sides of the body and is often associated to visuospatial, attentional, and social perception impairments. Here, we compared the performance of a sample of 30 children and adolescents with SpD (aged 7-18 years) and of a group of age-matched controls with typical development (TD) at two different tasks tapping on body representations. In the first task, we tested visual and motor imagery abilities as assessed, respectively, by the object-based mental rotation of letters and by the first-person transformations for whole-body stimuli. In the second task, we administered an inversion effect/composite illusion task to evaluate the use of configural/holistic processing of others' body. Additionally, we assessed social perception abilities in the SpD sample using the NEPSY-II battery. In line with previously reported visuospatial deficits, a general mental imagery impairment was found in SpD patients when they were engaged in both object-centered and first-person mental transformations. Nevertheless, a specific deficit in operating an own-body transformation emerged. As concerns body perception, while more basic configural processing (i.e., inversion effect) was spared, no evidence for holistic (i.e., composite illusion) body processing was found in the SpD group. NEPSY-II assessment revealed that SpD children were impaired in both the theory of mind and affect recognition subtests. Overall, these findings suggested that early brain lesions and biased embodied experience could affect higher-level motor cognition and perceptual body processing, thus pointing to a strict link between motor deficits, body schema alterations, and person processing difficulties

    A note on dimer models and McKay quivers

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    We give one formulation of an algorithm of Hanany and Vegh which takes a lattice polygon as an input and produces a set of isoradial dimer models. We study the case of lattice triangles in detail and discuss the relation with coamoebas following Feng, He, Kennaway and Vafa.Comment: 25 pages, 35 figures. v3:completely rewritte

    A-D-E Quivers and Baryonic Operators

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    We study baryonic operators of the gauge theory on multiple D3-branes at the tip of the conifold orbifolded by a discrete subgroup Gamma of SU(2). The string theory analysis predicts that the number and the order of the fixed points of Gamma acting on S^2 are directly reflected in the spectrum of baryonic operators on the corresponding quiver gauge theory constructed from two Dynkin diagrams of the corresponding type. We confirm the prediction by developing techniques to enumerate baryonic operators of the quiver gauge theory which includes the gauge groups with different ranks. We also find that the Seiberg dualities act on the baryonic operators in a non-Abelian fashion.Comment: 46 pages, 17 figures; v2: minor corrections, note added in section 1, references adde

    Comparison between continuous grazing and rotational grazing on roller chopped rangeland in central-west of La Pampa province

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    El control de la vegetación leñosa y la planificación posterior del pastoreo contribuirían a aumentar la oferta forrajera y la producción ganadera en pastizales del centro-oeste de la Provincia de La Pampa. El objetivo del presente trabajo fue comparar la dinámica de la vegetación y la respuesta animal en un pastizal rolado sometido a pastoreo continuo o pastoreo rotativo. La mitad de un área rolada de 200 ha se pastoreo en forma continua con terneros de recría, mientras que la restante mitad se pastoreo en forma rotativa mediante la subdivisión en cuatro parcelas de igual tamaño. Durante cuatro años consecutivos se realizaron mediciones sobre la vegetación (herbácea y leñosa) y sobre los animales. En el periodo de mediciones las lluvias fueron similares o superaron (hasta en un 33%) el promedio anual histórico. Los tratamientos de pastoreo (continuo y rotativo) no afectaron en forma diferencial la densidad de las gramíneas perennes palatables ni la cobertura de la vegetación leñosa, mientras que la disponibilidad de MS total promedio de las gramíneas perennes palatables fue mayor bajo pastoreo rotativo. La ganancia diaria de peso promedio de los animales en recría fue mayor bajo pastoreo continuo en tres de los cuatro años de medición. En el contexto del presente estudio no se expresó el potencial esperado del pastoreo rotativo, lo cual se interpreta en relación a las lluvias y a una potencial desmejora de la calidad del forraje consumido por los animales.Woody vegetation control and further grazing planning would contribute to increase forage availability and livestock production in rangelands of central-west La Pampa Province. The objective of present study was to compare vegetation dynamics and animal response in a roller chopped rangeland under continuous or rotational grazing. Half of a roller chopped area of 200 ha was continuously grazed with stocker cattle, whereas the other half was rotationally grazed through its subdivision in four parcels of equal size. Vegetation (herbaceous, woody) and animal responses were measured along a period of four consecutive years. During the study period rainfall was similar or above (up to 33%) the long-term annual average. Grazing treatments (continuous, rotational) did not differentially affect either density of palatable perennial grasses or woody vegetation cover, whereas total average DM availability of palatable perennial grasses was higher under rotational grazing. Average daily gain of stockers was higher under continuous grazing on three out of the four years of measurements. The expected potential of rotation grazing was not expressed under the context of present study, which is interpreted in relation to rainfall conditions and a potential deterioration in forage quality ingested by animals.Fil: Adema, E. O.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional La Pampa-San Luis. Estación Experimental Agropecuaria Anguil; ArgentinaFil: Butti, L. R.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional La Pampa-San Luis. Estación Experimental Agropecuaria Anguil; ArgentinaFil: Babinec, Francisco José. Instituto Nacional de Tecnología Agropecuaria. Centro Regional La Pampa-San Luis. Estación Experimental Agropecuaria Anguil; Argentina. Universidad Nacional de La Pampa. Facultad de Agronomía; ArgentinaFil: Distel, Roberto Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiarida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiarida; Argentin

    A Note on Supersymmetric Type II Solutions of Lifshitz Type

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    We discuss a class of supersymmetric type II non-relativistic solutions with exact or asymptotic scale invariance. As already emerged from previous investigations, we find a clear correspondence between anisotropic d-dimensional vacua and relativistic solutions in (d + 1)-dimensions. We will show that supersymmetric four-dimensional Poincare' invariant backgrounds in type IIB can descend to analogous solutions with anisotropic scaling in t and (x, y). This result can be applied to scale invariant theories, domain walls interpolating between four-dimensional Lifshitz vacua and more general solutions with only asymptotic or approximate scaling behaviour.Comment: Added subsection on hyperscaling violation example

    A Comparative Perspective on Minicolumns and Inhibitory GABAergic Interneurons in the Neocortex

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    Neocortical columns are functional and morphological units whose architecture may have been under selective evolutionary pressure in different mammalian lineages in response to encephalization and specializations of cognitive abilities. Inhibitory interneurons make a substantial contribution to the morphology and distribution of minicolumns within the cortex. In this context, we review differences in minicolumns and GABAergic interneurons among species and discuss possible implications for signaling among and within minicolumns. Furthermore, we discuss how abnormalities of both minicolumn disposition and inhibitory interneurons might be associated with neuropathological processes, such as Alzheimer's disease, autism, and schizophrenia. Specifically, we explore the possibility that phylogenetic variability in calcium-binding protein-expressing interneuron subtypes is directly related to differences in minicolumn morphology among species and might contribute to neuropathological susceptibility in humans
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