1,346 research outputs found
A Note on (Meta)stable Brane Configurations in MQCD
We examine the M-theory version of SQCD which is known as MQCD. In the IIA
limit, this theory appears to have a supersymmetry-breaking brane configuration
which corresponds to the meta-stable state of N=1 SU(Nc) SQCD. However, the
behavior at infinity of this non-supersymmetric brane construction differs from
that of the supersymmetric ground state of MQCD. We interpret this to mean that
it is not a meta-stable state in MQCD, but rather a state in another theory.
This provides a concrete example of the fact that, while MQCD accurately
describes the supersymmetric features of SCQD, it fails to reproduce its
non-supersymmetric features (such as meta-stable states) not only
quantitatively but also qualitatively.Comment: 30 pages, 7 figures, harvmac. v2 typo correcte
From Sasaki-Einstein spaces to quivers via BPS geodesics: Lpqr
The AdS/CFT correspondence between Sasaki-Einstein spaces and quiver gauge
theories is studied from the perspective of massless BPS geodesics. The
recently constructed toric Lpqr geometries are considered: we determine the
dual superconformal quivers and the spectrum of BPS mesons. The conformal
anomaly is compared with the volumes of the manifolds. The U(1)^2_F x U(1)_R
global symmetry quantum numbers of the mesonic operators are successfully
matched with the conserved momenta of the geodesics, providing a test of
AdS/CFT duality. The correspondence between BPS mesons and geodesics allows to
find new precise relations between the two sides of the duality. In particular
the parameters that characterize the geometry are mapped directly to the
parameters used for a-maximization in the field theory. The analysis simplifies
for the special case of the Lpqq models, which are shown to correspond to the
known "generalized conifolds". These geometries can break conformal invariance
through toric deformations of the complex structure.Comment: 30 pages, 8 figures, LaTeX. v2: One more figure. References added,
typos correcte
Moving constraints as stabilizing controls in classical mechanics
The paper analyzes a Lagrangian system which is controlled by directly
assigning some of the coordinates as functions of time, by means of
frictionless constraints. In a natural system of coordinates, the equations of
motions contain terms which are linear or quadratic w.r.t.time derivatives of
the control functions. After reviewing the basic equations, we explain the
significance of the quadratic terms, related to geodesics orthogonal to a given
foliation. We then study the problem of stabilization of the system to a given
point, by means of oscillating controls. This problem is first reduced to the
weak stability for a related convex-valued differential inclusion, then studied
by Lyapunov functions methods. In the last sections, we illustrate the results
by means of various mechanical examples.Comment: 52 pages, 4 figure
Immunogenetic features of steroid-sensitive nephrotic syndrome and focal segmental glomeru losclerosis in Brazilian patients of the northeast region of the state of São Paulo
A síndrome nefrótica corticossensível (SNCS) e a glomerulonefrite esclerosante segmentar e focal (GESF) compartilham características imunológicas e patogênicas. Foram estudados 93 pacientes brasileiros (46 com SNCS e 47 com GESF) e 104 indivíduos-controle, para caracterizar os perfis imunogenéticos dessas variedades de síndromes nefróticas idiopáticas. Os antígenos HLA-A, -B e –DR foram tipificados, usando-se método sorológico. Embora nenhuma associação com os antígenos HLA-A ou –B fosse observada, as freqüências dos antígenos HLAB7 e –B12 estavam significantemente elevadas nos pacientes com SNCS. Os antígenos HLADR7, HLA-DR1 e a combinação de antígenos HLA-DR1/DR7 estavam significantemente elevados nos pacientes com SNCS, em relação aos indivíduos-controle, ou em relação aos pacientes com GESF. A avaliação somente de pacientes caucasóides revelou que o antígeno HLA-DR7 continuava elevado nos pacientes com SNCS. O haplótipo HLA-B7/DR7 estava significantemente elevado nos pacientes com SNCS e GESF. Embora a população brasileira seja altamente miscigenada, a freqüência do antígeno HLA-DR7, que confere susceptibilidade a SNCS em outras populações, estava também elevada na série de pacientes caucasóides aqui estudada.Steroid-sensitive nephrotic syndrome (SSNS) and focal segmental glomerulosclerosis (FSGC) share immunologic and pathogenetic features. We studied 93 Brazilian patients (46 with SSNS and 47 with FSGC) and 104 control subjects with the objective of characterizing the immunogenetic profile of these varieties of idiopathic nephrotic syndrome. HLA-A, -B, and -DR antigens were typed using a complement-dependent microlymphocytotoxicity assay. No significanty association was observed with HLA-A or -B antigens in either group; however, HLA-B7 and -B12 antigens were increased in SSNS patients. HLA-DR7, -DR1 and the combination of HLA-DR1/DR7 antigens were significantly increased in the total group of patients with SSNS compared to controls or to FGSC patients. The study of only Caucasoid individuals revealed that HLA-DR7 antigen remained significantly increased in SSNS patients. The HLA-B7/DR7 haplotype was siginificantly increased in both SSNS and FSGC patients. Although the Brazilian population is highly miscigenated, the same antigen (HLA-DR7) which confers susceptibility to SSNS in other Caucasian population is still prevalent in this series
Holographic dual of the Standard Model on the throat
We apply recent techniques to construct geometries, based on local Calabi-Yau
manifolds, leading to warped throats with 3-form fluxes in string theory, with
interesting structure at their bottom. We provide their holographic dual
description in terms of RG flows for gauge theories with almost conformal
duality cascades and infrared confinement. We describe a model of a throat with
D-branes at its bottom, realizing a 3-family Standard Model like chiral sector.
We provide the explicit holographic dual gauge theory RG flow, and describe the
appearance of the SM degrees of freedom after confinement. As a second
application, we describe throats within throats, namely warped throats with
discontinuous warp factor in different regions of the radial coordinate, and
discuss possible model building applications.Comment: 46 pages, 21 figures, reference adde
On Type II Strings in Two Dimensions
We consider type IIA/B strings in two-dimensions and their projection with
respect to the nilpotent space-time supercharge. Based on the ground ring
structure, we propose a duality between perturbed type II strings and the
topological B-model on deformed Calabi-Yau singularities. Depending on the type
II spectra, one has either the conifold or the suspended pinch point geometry.
Using the corresponding quiver gauge theory, obtained by D-branes wrapping in
the resolved suspended pinch point geometry, we propose the all orders
perturbative partition function.Comment: 1+23 page
Myrtle Seeds (Myrtus communis L.) as a Rich Source of the Bioactive Ellagitannins Oenothein B and Eugeniflorin D2
The increasing popularity of "Mirto" liqueur, produced from Myrtus communis berries, has led to the planting of domesticated cultivars, expanding myrtle berry production. To promote the use of cultivated berries, the content in the nutraceutical compounds ellagitannins has been investigated both in spontaneous and cultivated fruits. Oenothein B and eugeniflorin D2, characterized by 1H and 13C NMR, were isolated and quantified using ultrahigh-performance liquid chromatography-diode array detector-tandem mass spectrometry (UPLC-DAD-MS/MS). The antifungal and anti-inflammatory activities of oenothein B were assayed in vitro. Large amounts of oenothein B and eugeniflorin D2 were detected in seeds (12 \ub1 2.4 and 5.8 \ub1 1.2 mg/g). The oenothein B concentration in liqueurs was 194 \ub1 22 mg/L. This macrocyclic ellagitannin dimer showed anti-Candida (minimal inhibitory concentration <8-64 \u3bcg/mL) and anti-inflammatory properties. Cultivated myrtle berries are a source of nutraceutical compounds. The high concentration of oenothein B in liqueur suggests a possible contribution to the organoleptic and biological properties of the beverage
ANGPTL3 gene variants in subjects with familial combined hyperlipidemia
Angiopoietin-like 3 (ANGPTL3) plays an important role in lipid metabolism in humans. Loss-of-function variants in ANGPTL3 cause a monogenic disease named familial combined hypolipidemia. However, the potential contribution of ANGPTL3 gene in subjects with familial combined hyperlipidemia (FCHL) has not been studied. For that reason, the aim of this work was to investigate the potential contribution of ANGPTL3 in the aetiology of FCHL by identifying gain-of-function (GOF) genetic variants in the ANGPTL3 gene in FCHL subjects. ANGPTL3 gene was sequenced in 162 unrelated subjects with severe FCHL and 165 normolipemic controls. Pathogenicity of genetic variants was predicted with PredictSNP2 and FruitFly. Frequency of identified variants in FCHL was compared with that of normolipemic controls and that described in the 1000 Genomes Project. No GOF mutations in ANGPTL3 were present in subjects with FCHL. Four variants were identified in FCHL subjects, showing a different frequency from that observed in normolipemic controls: c.607-109T>C, c.607-47_607-46delGT, c.835+41C>A and c.*52_*60del. This last variant, c.*52_*60del, is a microRNA associated sequence in the 3'UTR of ANGPTL3, and it was present 2.7 times more frequently in normolipemic controls than in FCHL subjects. Our research shows that no GOF mutations in ANGPTL3 were found in a large group of unrelated subjects with FCHL
An emerging, recognizable facial phenotype in association with mutations in GLI-similar 3 ( GLIS3 )
Neonatal diabetes and hypothyroidism (NDH) syndrome was first described in 2003 in a consanguineous Saudi Arabian family where two out of four siblings were reported to have presented with proportionate IUGR, neonatal non-autoimmune diabetes mellitus, severe congenital hypothyroidism, cholestasis, congenital glaucoma, and polycystic kidneys. Liver disease progressed to hepatic fibrosis. The renal disease was characterised by enlarged kidneys and multiple small cysts with deficient cortico-medullary junction differentiation and normal kidney function. There was minor facial dysmorphism (depressed nasal bridge, large anterior fontanelle, long philtrum) reported but no facial photographs were published. Mutations in the transcription factor GLI-similar 3 (GLIS3) gene in the original family and two other families were subsequently reported in 2006. All affected individuals had neonatal diabetes, congenital hypothyroidism but glaucoma and liver and kidney involvement were less consistent features. Detailed descriptions of the facial dysmorphism have not been reported previously. In this report, we describe the common facial dysmorphism consisting of bilateral low-set ears, depressed nasal bridge with overhanging columella, elongated, upslanted palpebral fissures, persistent long philtrum with a thin vermilion border of the upper lip in a cohort of seven patients with GLIS3 mutations and report the emergence of a distinct, probably recognisable facial gestalt in this group which evolves with age
Stringy Instantons and Cascading Quivers
D-brane instantons can perturb the quantum field theories on space-time
filling D-branes by interesting operators. In some cases, these D-brane
instantons are novel "stringy" effects (not interpretable directly as instanton
effects in the low-energy quantum field theory), while in others the D-brane
instantons can be directly interpreted as field theory effects. In this note,
we describe a situation where both perspectives are available, by studying
stringy instantons in quivers which arise at simple Calabi-Yau singularities.
We show that a stringy instanton which wraps an unoccupied node of the quiver,
and gives rise to a non-perturbative mass in the space-time field theory, can
be reinterpreted as a conventional gauge theory effect by going up in an
appropriate renormalization group cascade. Interestingly, in the cascade, the
contribution of the stringy instanton does not come from gauge theory
instantons but from strong coupling dynamics.Comment: 17 pages, 6 figures, harvma
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