206 research outputs found
Unitarity bounds and RG flows in time dependent quantum field theory
We generalize unitarity bounds on operator dimensions in conformal field
theory to field theories with spacetime dependent couplings. Below the energy
scale of spacetime variation of the couplings, their evolution can strongly
affect the physics, effectively shifting the infrared operator scaling and
unitarity bounds determined from correlation functions in the theory. We
analyze this explicitly for large- double-trace flows, and connect these to
UV complete field theories. One motivating class of examples comes from our
previous work on FRW holography, where this effect explains the range of
flavors allowed in the dual, time dependent, field theory.Comment: 38 page
On Coordinate Transformations in Planar Noncommutative Theories
We consider planar noncommutative theories such that the coordinates verify a
space-dependent commutation relation. We show that, in some special cases, new
coordinates may be introduced that have a constant commutator, and as a
consequence the construction of Field Theory models may be carried out by an
application of the standard Moyal approach in terms of the new coordinates. We
apply these ideas to the concrete example of a noncommutative plane with a
curved interface. We also show how to extend this method to more general
situations.Comment: 20 pages, 1 figure. references adde
Application of Vertical Brackets in Orthodontial Treatments: A Laser Speckle Study
This paper reports the application of a laser speckle technique for orthodontial studies. The purpose of these studies is to certify the validity of a proposal related with a new type of apparatus, and the methodology to be used in orthodontial treatments.
(Párrafo extraído a modo de resumen)</em
Respuestas fisiológicas y moleculares al déficit hídrico en trigo (Triticum aestivum L.)
Physiological and molecular responses of five wheat genotypes: one Canadian cultivar, with low temperature tolerance, and 4 experimental lines, which demonstrated in the field high yield under drought stress were studied under water stress. We determined leaf relative water content and gene expression of rob 5 and dehydrins in response to low water availability. One genotype showed a higher RWC with less leaf Iresh weight and water soil content. There were not differences between genotypes in expression genes but, we found differences in gene expression between both tested genes. Rob 5 expressed in control as well as in stressed plants, while dehydrins only expressed in stressed plants and its expression increased as the water content of leaves decreased.Las respuestas fisiológicas y moleculares de cinco genotipos de trigo: un cultivar canadiense. tolerante a las bajas temperaturas y 4 líneas experimentales argentinas, que habían mostrado, un alto rendimiento a campo bajo condiciones de deficiencia hídrica, fueron estudiadas en condiciones de baja disponibilidad de agua. Se determine el contenido relativo de agua en las hojas y la expresión de 2 genes, rob 5 y dehidrinas, en respuesta a la baja disponibilidad de agua. Uno de los genotipos mostró mayor CRA con un menor contenido de agua en las hojas o en el suelo. No hubo diferencias genotípicas en la expresión de los genes sin embargo, fue diferente la expresión de estos, en respuesta al estr6s hídrico, dado que el gen Rob 5 se expresó tanto en las plantas control como en las estresadas, mientras que el de las dehydrinas solo se expresó en las plantas bajo estrés, y su expresión aumentó en función de la disminución del contenido relativo de agua de las hojas
A microscopic theory of gauge mediation
We construct models of indirect gauge mediation where the dynamics
responsible for breaking supersymmetry simultaneously generates a weakly
coupled subsector of messengers. This provides a microscopic realization of
messenger gauge mediation where the messenger and hidden sector fields are
unified into a single sector. The UV theory is SQCD with massless and massive
quarks plus singlets, and at low energies it flows to a weakly coupled quiver
gauge theory. One node provides the primary source of supersymmetry breaking,
which is then transmitted to the node giving rise to the messenger fields.
These models break R-symmetry spontaneously, produce realistic gaugino and
sfermion masses, and give a heavy gravitino.Comment: 24 pages, 2 figures, accepted to JHEP for publicatio
Dynamic SU(2) Structure from Seven-branes
We obtain a family of supersymmetric solutions of type IIB supergravity with
dynamic SU(2) structure, which describe the local geometry near a stack of four
D7-branes and one O7-plane wrapping a rigid four-cycle. The deformation to a
generalized complex geometry is interpreted as a consequence of nonperturbative
effects in the seven-brane gauge theory. We formulate the problem for
seven-branes wrapping the base of an appropriate del Pezzo cone, and in the
near-stack limit in which the four-cycle is flat, we obtain an exact solution
in closed form. Our solutions serve to characterize the local geometry of
nonperturbatively-stabilized flux compactifications.Comment: 49 pages, 2 figures; v2: minor corrections, references adde
Massive IIA flux compactifications and U-dualities
We attempt to find a rigorous formulation for the massive type IIA
orientifold compactifications of string theory introduced in hep-th/0505160. An
approximate double T-duality converts this background into IIA string theory on
a twisted torus, but various arguments indicate that the back reaction of the
orientifold on this geometry is large. In particular, an AdS calculation of the
entropy suggests a scaling appropriate for N M2-branes, in a certain limit of
the compactification, though not the one studied in hep-th/0505160. The
M-theory lift of this specific regime is not 4 dimensional. We suggest that the
generic limit of the background corresponds to a situation analogous to
F-theory, where the string coupling is small in some regions of a compact
geometry, and large in others, so that neither a long wavelength 11D SUGRA
expansion, nor a world sheet expansion exists for these compactifications. We
end with a speculation on the nature of the generic compactification.Comment: JHEP3 LaTeX - 34 pages - 3 figures; v2: Added references; v3: mistake
in entropy scaling corrected, major changes in conclusions; v4: changed
claims about original DeWolfe et al. setup, JHEP versio
Using small molecules to facilitate exchange of bicarbonate and chloride anions across liposomal membranes
Bicarbonate is involved in a wide range of biological processes, which include respiration, regulation of intracellular pH and fertilization. In this study we use a combination of NMR spectroscopy and ion-selective electrode techniques to show that the natural product prodigiosin, a tripyrrolic molecule produced by microorganisms such as Streptomyces and Serratia, facilitates chloride/bicarbonate exchange (antiport) across liposomal membranes. Higher concentrations of simple synthetic molecules based on a 4,6-dihydroxyisophthalamide core are also shown to facilitate this antiport process. Although it is well known that proteins regulate Cl-/HCO3- exchange in cells, these results suggest that small molecules may also be able to regulate the concentration of these anions in biological systems
Meta-Stable Dynamical Supersymmetry Breaking Near Points of Enhanced Symmetry
We show that metastable supersymmetry breaking is generic near certain
enhanced symmetry points of gauge theory moduli spaces. Our model consists of
two sectors coupled by a singlet and combines dynamical supersymmetry breaking
with an O'Raifeartaigh mechanism in terms of confined variables. All relevant
mass parameters, including the supersymmetry breaking scale, are generated
dynamically. The metastable vacua appear as a result of a balance between
non-perturbative and perturbative quantum effects along a pseudo-runaway
direction.Comment: 27 pages, harvmac, 6 figure
PHF13: A new player involved in RNA polymerase II transcriptional regulation and co-transcriptional splicing
We recently identified PHF13 as an H3K4me2/3 chromatin reader and transcriptional co-regulator. We found that PHF13 interacts with RNAPIIS5P and PRC2 stabilizing their association with active and bivalent promoters. Furthermore, mass spectrometry analysis identified ∼50 spliceosomal proteins in PHF13s interactome. Here, we will discuss the potential role of PHF13 in RNAPII pausing and co-transcriptional splicing
- …
