901 research outputs found
Pure anti-de Sitter supergravity and the conformal bootstrap
We consider graviton scattering in maximal supergravity on Anti-de Sitter
space (AdS) in dimensions for d=3,4,\text{and 6} with no extra
compact spacetime factor. Holography suggests that this theory is dual to an
exotic maximally supersymmetric conformal field theory (CFT) in dimensions
whose only light single trace operator is the stress tensor. This contrasts
with more standard cases like Type IIB string theory on dual
to Super-Yang-Mills, where the CFT has light single trace
operators for each Kaluza-Klein mode on . We compute the 1-loop correction
to the pure AdS theory in a small Planck length expansion, which is
dual to the large central charge expansion in the CFT. We find that this
correction saturates the most general non-perturbative conformal bootstrap
bounds on this correlator in the large central charge regime for ,
while the 1-loop correction to CFTs with string/M-theory duals all lie inside
the allowed region.Comment: 6 pages plus appendices, 8 figures, v2 typos corrected and submitted
for publicatio
M-theory on at 1-loop and beyond
We study graviton scattering on , which is dual to the
stress tensor multiplet four-point function in the maximally supersymmetric 3d
ABJM theory. We compute 1-loop corrections to this
holographic correlator coming from Witten diagrams with supergravity and
higher derivative vertices, up to contact term ambiguities, and find that
the flat space limit matches the corresponding terms in the 11d M-theory
S-matrix. We then use supersymmetric localization to show that all the 1-loop
contact terms vanish, as was previously observed for the theory dual to ABJM. Finally, we use
the recent localization results of Gaiotto and Abajian, as inspired by twisted
M-theory, to compute all the short OPE coefficients in correlators of the
stress tensor multiplet and the next lowest half-BPS operator, which we find
saturate the bootstrap bounds on these mixed correlators for all .Comment: 20 pages, 2 figures, sequel to arXiv:2107.1027
6d (2,0) and M-theory at 1-loop
We study the stress tensor multiplet four-point function in the 6d maximally
supersymmetric and theories, which have no Lagrangian
description, but in the large limit are holographically dual to weakly
coupled M-theory on and ,
respectively. We use the analytic bootstrap to compute the 1-loop correction to
this holographic correlator coming from Witten diagrams with supergravity
and the first higher derivative correction vertices, which is the first
1-loop correction computed for a non-Lagrangian theory. We then take the flat
space limit and find precise agreement with the corresponding terms in the 11d
M-theory S-matrix, some of which we compute for the first time using
two-particle unitarity cuts.Comment: 35 pages plus appendices, v4 typos corrected, accepted to JHE
Variación del proteoma de las micropartículas plaquetarias dependiendo del estímulo: papel de las proteínas de señalización
Comunicaciones a congreso
Relations between integrated correlators in Supersymmetric Yang--Mills Theory
Integrated correlation functions in supersymmetric
Yang--Mills theory with gauge group can be expressed in terms of the
localised partition function, , deformed by a mass . Two such
cases are and , which are modular invariant functions of the complex coupling
. While was recently written in terms of a
two-dimensional lattice sum for any and , has only
been evaluated up to order in a large- expansion in terms of modular
invariant functions with no known lattice sum realisation. Here we develop
methods for evaluating to any desired order in and finite
. We use this new data to constrain higher loop corrections to the stress
tensor correlator, and give evidence for several intriguing relations between
and to all orders in . We also give
evidence that the coefficients of the expansion of can be
written as lattice sums to all orders. Lastly, these large and finite
results are used to accurately estimate the integrated correlators at
finite and finite .Comment: 30 pages plus appendices, 8 figure
Novel Adaptive Photosynthetic Characteristics of Mesophotic Symbiotic Microalgae within the Reef-Building Coral, Stylophora pistillata
Photosynthetic coral reef structures extend from the shallow sundrenched waters to the dimly lit, “twilight” mesophotic depths. For their resident endosymbiotic dinoflagellates, primarily from the genus Symbiodinium spp., this represents a photic environment that varies ~15-fold in intensity and also differs in spectral composition. We examined photosynthesis in the scleractinian coral Stylophora pistillata in shallow (3 m) and mesophotic settings (65 m) in the northern Red Sea. Symbiodinium spp. in corals originating from the mesophotic environment consistently performed below their photosynthetic compensation point and also exhibited distinct light harvesting antenna organization. In addition, the non-photochemical quenching activity of Symbiodinium spp. from mesophotic corals was shown to be considerably lower than those found in shallow corals, showing they have fewer defenses to high-light settings. Over a period of almost 4 years, we extensively utilized closed circuit Trimix rebreather diving to perform the study. Phylogenetic analysis showed that shallow corals (3 m) transplanted to a deep reef environment (65 m) maintained their initial Symbiodinium spp. community (clade A), rather than taking on deep low-light clades (clade C), demonstrating that shallow S. pistillata acclimate to low-light mesophotic environments while maintaining their shallow photosynthetic traits. Mesophotic corals exhibited static depth-related chlorophyll content per cell, a decrease in PSI activity and enhanced sigmoidal fluorescence rise kinetics. The sigmoidal fluorescence rise kinetics we observed in mesophotic corals is an indication of energy transfer between photosynthetic units. We postulate that at mesophotic depths, a community of adapted Symbiodinium spp. utilize a unique adaptation to lower light conditions by shifting their light harvesting to a PSII based system, where PSII is structured near PSI, with additional PCP soluble antenna also trapping light that is funneled to the PSI reaction center. In this study, we provide evidence that mesophotic Symbiodinium spp. have developed novel adaptive low-light characteristics consisting of a cooperative system for excitation energy transfer between photosynthetic units that maximizes light utilization
The X-ray Properties of z>4 Quasars
We report on a search for X-ray emission from quasars with redshifts greater
than four using the ROSAT public database. Our search has doubled the number of
z>4 quasars detected in X-rays from 6 to 12. Most of those known prior to this
work were radio-loud and X-ray selected sources; our study increases the number
of X-ray detected, optically selected z>4 quasars from one to seven. We present
their basic X-ray properties and compare these to those of lower redshift
quasars. We do not find any evidence for strong broad-band spectral differences
between optically selected z>4 quasars and those at lower redshifts.Comment: 7 pages, 4 figures included, LaTeX emulateapj.sty, accepted for
publication in the Astronomical Journa
Unlocking the in vitroanti- inflammatory and antidiabetic potential of Polygonum maritimum
Context: Several Polygonum species (Polygonaceae) are used in traditional medicine in Asia, Europe and Africa to treat inflammation and diabetes. Objective: Evaluate the in vitro antioxidant, anti-inflammatory and antidiabetic potential of methanol and dichloromethane extracts of leaves and roots of the halophyte Polygonum maritimum L. Material and methods: Antioxidant activity was determined (up to 1mg/mL) as radical-scavenging activity (RSA) of 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), copper (CCA) and iron (ICA) chelating activities and iron reducing power (FRAP). NO production was measured in lipopolysaccharide (LPS)-stimulated macrophages for 24 h at concentrations up to 100 mu g/mL and antidiabetic potential was assessed by alpha-amylase and alpha-glucosidase inhibition (up to 10 g/mL) assays. The phytochemical composition of the extracts was determined by gas chromatography-mass spectrometry (GC-MS). Results: The methanol leaf extract had the highest activity against DPPH center dot (IC50 = 26 mu g/mL) and ABTS1(+)center dot (IC50 = 140 mu g FRAP (IC50 = 48 mu g/mL) and CCA (IC50 = 770 mu g/mL). Only the dichloromethane leaf extract (LDCM) showed anti-inflammatory activity (IC50 = 48 mu g/mL). The methanol root (IC50 = 19 mu g/mL) and leaf (IC50 = 29 mu g/mL) extracts strongly inhibited baker's yeast alpha-glucosidase, but LDCM had higher rat's alpha-glucosidase inhibition (IC50 = 2527 mu g/mL) than acarbose (IC50 = 4638 mu g/mL). GC-MS analysis identified beta-sitosterol, stigmasterol, 1-octacosanol and linolenic acid as possible molecules responsible for the observed bioactivities. Conclusions: Our findings suggest P. maritimum as a source of high-value health promoting commodities for alleviating symptoms associated with oxidative and inflammatory diseases, including diabetes.XtremeBio project - Foundation for Science and Technology (FCT) [PTDC/MAR-EST/4346/2012]; Portuguese National Budget; FCT [CCMAR/Multi/04326/ 2013, IF/00049/2012, SFRH/BPD/86071/2012, UID/Multi/00612/2013
Genetic Parameters of White Striping and Meat Quality Traits Indicative of Pale, Soft, Exudative Meat in Turkeys (Meleagris gallopavo).
Due to the increasing prevalence of growth-related myopathies and abnormalities in turkey meat, the ability to include meat quality traits in poultry breeding strategies is an issue of key importance. In the present study, genetic parameters for meat quality traits and their correlations with body weight and meat yield were estimated using a population of purebred male turkeys. Information on live body, breast, thigh, and drum weights, breast meat yield, feed conversion ratio, breast lightness (L*), redness (a*), and yellowness (b*), ultimate pH, and white striping (WS) severity score were collected on 11,986 toms from three purebred genetic lines. Heritability and genetic and partial phenotypic correlations were estimated for each trait using an animal model with genetic line, hatch week-year, and age at slaughter included as fixed effects. Heritability of ultimate pH was estimated to be 0.34 ± 0.05 and a range of 0.20 ± 0.02 to 0.23 ± 0.02 for breast meat colour (L*, a*, and b*). White striping was also estimated to be moderately heritable at 0.15 ± 0.02. Unfavorable genetic correlations were observed between body weight and meat quality traits as well as white striping, indicating that selection for increased body weight and meat yield may decrease pH and increase the incidence of pale meat with more severe white striping. The results of this analysis provide insight into the effect of current selection strategies on meat quality and emphasize the need to include meat quality traits into future selection indexes for turkeys
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