16,668 research outputs found

    D-brane Instantons as Gauge Instantons in Orientifolds of Chiral Quiver Theories

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    Systems of D3-branes at orientifold singularities can receive non-perturbative D-brane instanton corrections, inducing field theory operators in the 4d effective theory. In certain non-chiral examples, these systems have been realized as the infrared endpoint of a Seiberg duality cascade, in which the D-brane instanton effects arise from strong gauge theory dynamics. We present the first UV duality cascade completion of chiral D3-brane theories, in which the D-brane instantons arise from gauge theory dynamics. Chiral examples are interesting because the instanton fermion zero mode sector is topologically protected, and therefore lead to more robust setups. As an application of our results, we provide a UV completion of certain D-brane orientifold systems recently claimed to produce conformal field theories with conformal invariance broken only by D-brane instantons.Comment: 50 pages, 32 figures. v2: version published in JHEP with references adde

    New checks and subtleties for AdS/CFT and a-maximization

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    We provide a cross-check of AdS/CFT and a-charge maximization for a four dimensional NN=1 SCFT with irrational R-charges. The gauge theory is the low energy effective theory of N D3-branes at the tip of the complex cone over the first del Pezzo surface. By carefully taking into account the subtle issue of flavor symmetry breaking at the fixed point, we show, using a-maximization, that this theory has in fact irrational central charge and R-charges. Our results perfectly match with those inherited from the recently discovered supergravity dual background. Along analogous lines, we make novel predictions for the still unknown AdS dual of the quiver theory for the second del Pezzo surface. This should flow to a SCFT with irrational charges, too. All of our results differ from previous findings in the literature and outline interesting subtleties in a-maximization and AdS/CFT techniques overlooked in the past.Comment: Latex, 16 pagex, 2 figures; v2, comments and a reference added; v3, typos correcte

    Highly Active and Stable NiCuMo Electrocatalyst Supported on 304 Stainless Steel Porous Transport Layer for Hydrogen Evolution in Alkaline Water Electrolyzer

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    Several functionalized porous transport layers with Pt-free electrocatalysts for hydrogen evolution reaction in alkaline conditions, based on Ni, Cu, and Mo, are prepared through electrodeposition onto a 304 stainless steel mesh. Morphological characterization confirms the fabrication of electrodes with high electrochemical surface active area due to the formation of hierarchical nanostructures. Mo presence into the electrocatalysts increases the activity toward the hydrogen evolution reaction. The optimization of electrodeposition process leads to the preparation of highly active NiCuMo electrocatalyst that exhibits near zero onset overpotential and overpotentials of 15 and 113 mV at 10 and 100 mA cm(-2), respectively, in 1 m KOH electrolyte. Moreover, this electrocatalyst shows superior stability with respect to other Pt-free electrocatalysts, reaching 100 h of durability with low overpotentials value demonstrating the successful preparation of very promising functionalized porous transport layers for future-generation alkaline electrolyzers

    Neuropsychomotricity in water: A new rehabilitative tool for neruodevelop-mental disorders

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    Neuropsychomotricity in water is a rehabilitative practice that avails itself just of the liquid element, as a mediator of relationships: in water yes they upset all dynamics, be they relational, of equilibrium, of movement and perception, due to the fact that proprioceptive sensations, created by bodily contact with water, they are different than those generated by contact with air

    Eating and feeding disorders in pediatric age

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    Eating and feeding disorders are common in pediatric age and may be important to discover and recover the early symptoms in order to optimize the treatment and management

    Visuospatial skills in children affected by primary nocturnal enuresis: Rehabilitative proposals

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    The sphincterial control problems in childhood are very common, with relevant comorbidities (i.e.: difficulty in academic performance, sleep disturbances, minor neurological signs) involved in the complex process of maturation and learning, such as to cause a great deal of discomfort and related disorders in affected subjects. Enuresis is characterized by the involuntary urination in the absence of a physical disorder, socially unacceptable in places and at one stage of life where such control is acquired by the majority of subjects (about 5 years). The present study aims to evaluate the visuospatial skills in children affected by primary monosymptomatic nocturnal enuresis (PMNE). 31 PMNE children (16 males and 15 females) (mean age 10.87, SD ± 1.68) and 61 healthy children (32 males, 29 females) (mean age 11.03, SD ± 1.85, p = 0687) were evaluated for visuomotor skills with the Visual-Motor Integration Scale (VMI). PMNE subjects show a worse performance on average to VMI, especially in the total visual-motor integration test. This finding emphasizes the importance of a framework for global and more complex than is commonly implemented, across the border but framing the subject of enuretic symptoms in a more global perspective

    A brief review about anxiety and aggressive behavior in pediatric age

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    Anxiety can be considered a normal experience of the human being and as such also of the child. It manifests itself in different ways according to the level of development: in the smaller the child, the more anxiety is expressed with manifestations that involve the whole organism, becoming evident either with motor excitement or with physical discomfort. As the psychic apparatus is structured, anxiety is experienced as an inner phenomenon and is experienced as an unpleasant state. Fortunately, we are all a bit anxious, even if there are some people who are more, others less

    Psychopathological and psychodynamic hypotheses for pediatric stuttering

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    Stuttering is a common language alteration in pediatric age consisting in repetitions and blocks, which entail a break in the rhythm and melody of the speech. According to the WHO it is a disorder of the rhythm of the word, the subject knows precisely what he would like to say, but at the same time he is not able to say it. It is a great inconvenience for those affected, also because the slowing down of speaking is not about thought or cognitive skills
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