887 research outputs found

    Zero-modes on orbifolds : magnetized orbifold models by modular transformation

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    We study T2/ZNT^2/Z_N orbifold models with magnetic fluxes. We propose a systematic way to analyze the number of zero-modes and their wavefunctions by use of modular transformation. Our results are consistent with the previous results, and our approach is more direct and analytical than the previous ones. The index theorem implies that the zero-mode number of the Dirac operator on T2T^2 is equal to the index MM, which corresponds to the magnetic flux in a certain unit. Our results show that the zero-mode number of the Dirac operator on T2/ZNT^2/Z_N is equal to M/N+1\lfloor M/N \rfloor +1 except one case on the T2/Z3T^2/Z_3 orbifold.Comment: 30 page

    Modular symmetry in magnetized/intersecting D-brane models

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    We study the modular symmetry in four-dimensional low-energy effective field theory, which is derived from type IIB magnetized D-brane models and type IIA intersecting D-brane models. We analyze modular symmetric behaviors of perturbative terms and non-perturbative terms induced by D-brane instanton effects. Anomalies are also investigated and such an analysis on anomalies suggests corrections in effective field theory.Comment: 18 page

    Carrying and Effect of Granulated Baits Formulated with Entomopathogenic Fungi among Atta sexdens rubropilosa Colonies (Hymenoptera: Formicidae)

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    The present study aimed to evaluate the carrying and effect of (dry) granulated baits containing conidia of entomopathogenic fungi among colonies of the leaf-cutting ant Atta sexdens rubropilosa in the laboratory. This bait type was chosen to facilitate its eventual commercial use. Two applications were performed: in the first, baits with 1x108 conidia/g were utilized while in the second employed concentrations 5 to 8.6 times greater. The baits were formulated with a citric pulp base, with 2 isolates of Beauveria bassiana, 1 of Paecilomyces lilacinus and 1 of Isaria fumosorosea. The following controls were utilized: (I) baits with sulfluramid insecticide, (II) without active ingredient, and (III) Acalypha spp. leaf discs. It was verified that the baits containing fungal conidia were rapidly carried to the nest interior in both applications and were rejected minimally. Thus, the (dry) granulated bait formulation appears to be an adequate vehicle for entomopathogenic fungi. At the doses and concentrations utilized, the fungi provoked only limited worker mortality, not killing the colonies. Given the rapid carrying and low rejection, a higher conidial dose per colony can, perhaps, kill them. Thus, it is inferred that all the isolates tested present potential as an agent to control colonies of leaf-cutting ants

    Modular symmetry and non-Abelian discrete flavor symmetries in string compactification

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    We study the modular symmetry in magnetized D-brane models on T2T^2. Non-Abelian flavor symmetry D4D_4 in the model with magnetic flux M=2M=2 (in a certain unit) is a subgroup of the modular symmetry. We also study the modular symmetry in heterotic orbifold models. The T2/Z4T^2/Z_4 orbifold model has the same modular symmetry as the magnetized brane model with M=2M=2, and its flavor symmetry D4D_4 is a subgroup of the modular symmetry.Comment: 28 page

    Synthesis and textural properties of unsupported and supported rutile (TiO2) membranes

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    Two approaches were postulated for improving the stability of porous texture of titania membranes: (1) retarding the phase transformation and grain growth; (2) avoiding the phase transformation. Based on the second approach, rutile membranes were made directly from a rutile sol, prepared by the precipitation of titania on SnO2 nuclei. The rutile membranes were stable up to 800 °C, with a porosity of ca. 40%, whereas normal titania membranes (starting with anatase) show very little porosity above 600 °C. Alumina substitution retards grain growth and pore growth at 850 °C for unsupported as well as supported membranes. \u

    Textural evolution and phase transformation in titania membranes: Part 2. - Supported membranes

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    Nanostructural evolution and phase transformation in supported and unsupported titania membranes have been studied using Raman spectroscopy, X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). Densification of unsupported membranes started at ca. 450 °C and reached more than 97% density at 600 °C, whereas the supported membranes had a density of only ca. 70–75% even at 700 °C when calcined for 8 h. At 700 °C the average crystallite size of supported and unsupported membranes was ca. 20 and 70 nm, respectively. This behaviour is primarily attributed to the decrease in the driving force for sintering due to the stress developed during the constrained sintering of a film attached to a rigid support and to the inhibition of the reorganization process within the film, resulting in lower coordination numbers in supported membranes. Supported membranes showed a higher transformation temperature (slower rate of transformation) than did the unsupported. Supported and unsupported membranes, calcined for 8 h, transformed to ca. 90% rutile (calculated from Raman spectrum) after calcination at 850 and 650 °C, respectively. This difference in phase transformation behaviour is attributed primarily to the large stress which is developed in a constrained environment owing to the negative volume change during the anatase–rutile transformation

    Cryogenic propellant venting under low pressure conditions final report

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    Cryogenic propellant venting under low pressure conditions - heat-transfer coefficients for two- phase, single component, solid-gas mixture flow in short, vertical tub

    HLA-II-Dependent Neuroimmune Changes in Group A Streptococcal Necrotizing Fasciitis

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    Streptococcus pyogenes (Group A Streptococcus, GAS) bacteria cause a spectrum of human diseases ranging from self-limiting pharyngitis and mild, uncomplicated skin infections (impetigo, erysipelas, and cellulitis) to highly morbid and rapidly invasive, life-threatening infections such as streptococcal toxic shock syndrome and necrotizing fasciitis (NF). HLA class II allelic polymorphisms are linked with differential outcomes and severity of GAS infections. The dysregulated immune response and peripheral cytokine storm elicited due to invasive GAS infections increase the risk for toxic shock and multiple organ failure in genetically susceptible individuals. We hypothesized that, while the host immune mediators regulate the immune responses against peripheral GAS infections, these interactions may simultaneously trigger neuropathology and, in some cases, induce persistent alterations in the glial phenotypes. Here, we studied the consequences of peripheral GAS skin infection on the brain in an HLA-II transgenic mouse model of GAS NF with and without treatment with an antibiotic, clindamycin (CLN). Mice expressing the human HLA-II DR3 (DR3) or the HLA-II DR4 (DR4) allele were divided into three groups: (i) uninfected controls, (ii) subcutaneously infected with a clinical GAS strain isolated from a patient with GAS NF, and (iii) GAS-infected with CLN treatment (10 mg/kg/5 days, intraperitoneal). The groups were monitored for 15 days post-infection. Skin GAS burden and lesion area, splenic and hippocampal mRNA levels of inflammatory markers, and immunohistochemical changes in hippocampal GFAP and Iba-1 immunoreactivity were assessed. Skin GAS burden and hippocampal mRNA levels of the inflammatory markers S100A8/A9, IL-1β, IL-33, inflammasome-related caspase-1 (Casp1), and NLRP6 were elevated in infected DR3 but not DR4 mice. The levels of these markers were significantly reduced following CLN treatment in DR3 mice. Although GAS was not detectable in the brain, astrocyte (GFAP) and microglia (Iba-1) activation were evident from increased GFAP and Iba-1 mRNA levels in DR3 and DR4 mice. However, CLN treatment significantly reduced GFAP mRNA levels in DR3 mice, not DR4 mice. Our data suggest a skin–brain axis during GAS NF, demonstrating that peripherally induced pathological conditions regulate neuroimmune changes and gliotic events in the brai
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