6,614 research outputs found
Monodromy--like Relations for Finite Loop Amplitudes
We investigate the existence of relations for finite one-loop amplitudes in
Yang-Mills theory. Using a diagrammatic formalism and a remarkable connection
between tree and loop level, we deduce sequences of amplitude relations for any
number of external legs.Comment: 24 pages, 6 figures, v2 typos corrected, reference adde
The RN/CFT Correspondence Revisited
We reconsidered the quantum gravity description of the near horizon extremal
Reissner-Nordstr{\o}m black hole in the viewpoint of the AdS/CFT
correspondence. We found that, for pure electric case, the right moving central
charge of dual 1D CFT is which is different from the previous result of left moving sector obtained by warped AdS/CFT description. We
discussed the discrepancy in these two approaches and examined novel properties
of our result.Comment: revtex4, 16 pages, sign mistakes corrected, references include
Ultrashort nonautonomous similariton solutions and the cascade tunneling of interacting similaritons
Similarity transformation and Hirota bilinearization are deployed to derive exact bright and dark ultrashort
one- and two-similariton solutions of a nonautonomous cubic-quintic nonlinear Schrödinger equation. Such wave packets
may emerge when group-velocity dispersion and cubic-quintic self-phase modulations are balanced by Raman self-frequency
shift in the presence of an external harmonic trap and linear gain or loss. The solutions presented here can be used to
investigate the compression, amplification and interaction phenomena associated with bright and dark similaritons in
inhomogeneous fiber systems. Furthermore, the dynamics of the characteristic parameters of the similaritons are studied
analytically, and similariton stability in a distributed system is tested through extensive computations. As an example
application, the tunneling behavior of bright and dark similaritons through cascade dispersion barriers and dispersion wells on
an exponential background is investigated, and some interesting novel features are uncovered which are expected to facilitate
the control of bright and dark ultrashort similariton in experimental scenarios
The momentum analyticity of two-point correlators from perturbation theory and AdS/CFT
The momentum plane analyticity of two point function of a relativistic
thermal field theory at zero chemical potential is explored. A general
principle regarding the location of the singularities is extracted. In the case
of the N=4 supersymmetric Yang-Mills theory at large , a qualitative
change in the nature of the singularity (branch points versus simple poles)
from the weak coupling regime to the strong coupling regime is observed with
the aid of the AdS/CFT correspondence.Comment: 18 pages, 3 figures, typos fixed, 1 figure update
Scale invariance and universality of force networks in static granular matter
Force networks form the skeleton of static granular matter. They are the key
ingredient to mechanical properties, such as stability, elasticity and sound
transmission, which are of utmost importance for civil engineering and
industrial processing. Previous studies have focused on the global structure of
external forces (the boundary condition), and on the probability distribution
of individual contact forces. The disordered spatial structure of the force
network, however, has remained elusive so far. Here we report evidence for
scale invariance of clusters of particles that interact via relatively strong
forces. We analyzed granular packings generated by molecular dynamics
simulations mimicking real granular matter; despite the visual variation, force
networks for various values of the confining pressure and other parameters have
identical scaling exponents and scaling function, and thus determine a
universality class. Remarkably, the flat ensemble of force configurations--a
simple generalization of equilibrium statistical mechanics--belongs to the same
universality class, while some widely studied simplified models do not.Comment: 15 pages, 4 figures; to appear in Natur
Strongly Enhanced Current Densities in Superconducting Coated Conductors of YBa2Cu3O7-x + BaZrO3
There are numerous potential applications for superconducting tapes, based on
YBa2Cu3O7-x (YBCO) films coated onto metallic substrates. A long established
goal of more than 15 years has been to understand the magnetic flux pinning
mechanisms which allow films to maintain high current densities out to high
magnetic fields. In fact, films carry 1-2 orders of magnitude higher current
densities than any other form of the material. For this reason, the idea of
further improving pinning has received little attention. Now that
commercialisation of conductors is much closer, for both better performance and
lower fabrication costs, an important goal is to achieve enhanced pinning in a
practical way. In this work, we demonstrate a simple and industrially scaleable
route which yields a 1.5 to 5-fold improvement in the in-field current
densities of already-high-quality conductors
Multiomic features associated with mucosal healing and inflammation in paediatric Crohn's disease
Background
The gastrointestinal microbiota has an important role in mucosal immune homoeostasis and may contribute to maintaining mucosal healing in Crohn's disease (CD).
Aim
To identify changes in the microbiota, metabolome and protease activity associated with mucosal healing in established paediatric CD.
Methods
Twentyâfive participants aged 3â18 years with CD, disease duration of over 6 months, and maintenance treatment with biological therapy were recruited. They were divided into a low calprotectin group (faecal calprotectin 100 ÎŒg/g, âmucosal inflammation,â n = 11). 16S geneâbased metataxonomics, 1HâNMR spectroscopyâbased metabolic profiling and protease activity assays were performed on stool samples.
Results
Relative abundance of Dialister species was six times greater in the low calprotectin group (q = 0.00999). Alpha and beta diversity, total protease activity and inferred metagenomic profiles did not differ between groups. Pentanoate (valerate) and lysine were principal discriminators in a machineâlearning model which differentiated high and low calprotectin samples using NMR spectra (R2 0.87, Q2 0.41). Mean relative concentration of pentanoate was 1.35âtimes greater in the low calprotectin group (95% CI 1.03â1.68, P = 0.036) and was positively correlated with Dialister. Mean relative concentration of lysine was 1.54âtimes greater in the high calprotectin group (95% CI 1.05â2.03, P = 0.028).
Conclusions
This multiomic study identified an increase in Dialister species and pentanoate, and a decrease in lysine, in patients with âmucosal healing.â It supports further investigation of these as potential novel therapeutic targets in CD
Note on New KLT relations
In this short note, we present two results about KLT relations discussed in
recent several papers. Our first result is the re-derivation of Mason-Skinner
MHV amplitude by applying the S_{n-3} permutation symmetric KLT relations
directly to MHV amplitude. Our second result is the equivalence proof of the
newly discovered S_{n-2} permutation symmetric KLT relations and the well-known
S_{n-3} permutation symmetric KLT relations. Although both formulas have been
shown to be correct by BCFW recursion relations, our result is the first direct
check using the regularized definition of the new formula.Comment: 15 Pages; v2: minor correction
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