19,166 research outputs found
Management of intestinal transplantation in humans
We report here the clinical experience and management guidelines for the nine consecutive cases who received either an isolated small intestinal graft (n = 1) or an intestine liver combination at the University of Pittsburgh, with FK 506 being the basic immunosuppressive drug therapy
On classical q-deformations of integrable sigma-models
JHEP is an open-access journal funded by SCOAP3 and licensed under CC BY 4.0A procedure is developed for constructing deformations of integrable σ-models which are themselves classically integrable. When applied to the principal chiral model on any compact Lie group F, one recovers the Yang-Baxter σ-model introduced a few years ago by C. Klimčík. In the case of the symmetric space σ-model on F/G we obtain a new one-parameter family of integrable σ-models. The actions of these models correspond to a deformation of the target space geometry and include a torsion term. An interesting feature of the construction is the q-deformation of the symmetry corresponding to left multiplication in the original models, which becomes replaced by a classical q-deformed Poisson-Hopf algebra. Another noteworthy aspect of the deformation in the coset σ-model case is that it interpolates between a compact and a non-compact symmetric space. This is exemplified in the case of the SU(2)/U(1) coset σ-model which interpolates all the way to the SU(1, 1)/U(1) coset σ-modelPeer reviewedFinal Published versio
Excited states nonlinear integral equations for an integrable anisotropic spin 1 chain
We propose a set of nonlinear integral equations to describe on the excited
states of an integrable the spin 1 chain with anisotropy. The scaling
dimensions, evaluated numerically in previous studies, are recovered
analytically by using the equations. This result may be relevant to the study
on the supersymmetric sine-Gordon model.Comment: 15 pages, 2 Figures, typos correcte
Conjugacy theorems for loop reductive group schemes and Lie algebras
The conjugacy of split Cartan subalgebras in the finite dimensional simple
case (Chevalley) and in the symmetrizable Kac-Moody case (Peterson-Kac) are
fundamental results of the theory of Lie algebras. Among the Kac-Moody Lie
algebras the affine algebras stand out. This paper deals with the problem of
conjugacy for a class of algebras --extended affine Lie algebras-- that are in
a precise sense higher nullity analogues of the affine algebras. Unlike the
methods used by Peterson-Kac, our approach is entirely cohomological and
geometric. It is deeply rooted on the theory of reductive group schemes
developed by Demazure and Grothendieck, and on the work of J. Tits on buildingsComment: Publi\'e dans Bulletin of Mathematical Sciences 4 (2014), 281-32
(pi,pi)-electronic order in iron arsenide superconductors
The distribution of valence electrons in metals usually follows the symmetry
of an ionic lattice. Modulations of this distribution often occur when those
electrons are not stable with respect to a new electronic order, such as spin
or charge density waves. Electron density waves have been observed in many
families of superconductors[1-3], and are often considered to be essential for
superconductivity to exist[4]. Recent measurements[5-9] seem to show that the
properties of the iron pnictides[10, 11] are in good agreement with band
structure calculations that do not include additional ordering, implying no
relation between density waves and superconductivity in those materials[12-15].
Here we report that the electronic structure of Ba1-xKxFe2As2 is in sharp
disagreement with those band structure calculations[12-15], instead revealing a
reconstruction characterized by a (pi,pi) wave vector. This electronic order
coexists with superconductivity and persists up to room temperature
All-Versus-Nothing Proof of Einstein-Podolsky-Rosen Steering
Einstein-Podolsky-Rosen steering is a form of quantum nonlocality
intermediate between entanglement and Bell nonlocality. Although Schr\"odinger
already mooted the idea in 1935, steering still defies a complete
understanding. In analogy to "all-versus-nothing" proofs of Bell nonlocality,
here we present a proof of steering without inequalities rendering the
detection of correlations leading to a violation of steering inequalities
unnecessary. We show that, given any two-qubit entangled state, the existence
of certain projective measurement by Alice so that Bob's normalized conditional
states can be regarded as two different pure states provides a criterion for
Alice-to-Bob steerability. A steering inequality equivalent to the
all-versus-nothing proof is also obtained. Our result clearly demonstrates that
there exist many quantum states which do not violate any previously known
steering inequality but are indeed steerable. Our method offers advantages over
the existing methods for experimentally testing steerability, and sheds new
light on the asymmetric steering problem.Comment: 7 pages, 2 figures. Accepted in Sci. Re
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
Numerical Hermitian Yang-Mills Connections and Kahler Cone Substructure
We further develop the numerical algorithm for computing the gauge connection
of slope-stable holomorphic vector bundles on Calabi-Yau manifolds. In
particular, recent work on the generalized Donaldson algorithm is extended to
bundles with Kahler cone substructure on manifolds with h^{1,1}>1. Since the
computation depends only on a one-dimensional ray in the Kahler moduli space,
it can probe slope-stability regardless of the size of h^{1,1}. Suitably
normalized error measures are introduced to quantitatively compare results for
different directions in Kahler moduli space. A significantly improved numerical
integration procedure based on adaptive refinements is described and
implemented. Finally, an efficient numerical check is proposed for determining
whether or not a vector bundle is slope-stable without computing its full
connection.Comment: 38 pages, 10 figure
Speech Features for Discriminating Stress Using Branch and Bound Wrapper Search
Stress detection from speech is a less explored field than Automatic Emotion Recognition and it is still not clear which features are better stress discriminants. VOCE aims at doing speech classification as stressed or not-stressed in real-time, using acoustic-prosodic features only. We therefore look for the best discriminating feature subsets from a set of 6285 features – 6125 features extracted with openSMILE toolkit and 160 Teager Energy Operator (TEO) features. We use a mutual information filter and a branch and bound wrapper heuristic with an SVM classifier to perform feature selection. Since many feature sets are selected, we analyse them in terms of chosen features and classifier performance concerning also true positive and false positive rates. The results show that the best feature types for our application case are Audio Spectral, MFCC, PCM and TEO. We reached results as high as 70.36% for generalisation accuracyinfo:eu-repo/semantics/publishedVersio
Drop Traffic in Microfluidic Ladder Networks with Fore-Aft Structural Asymmetry
We investigate the dynamics of pairs of drops in microfluidic ladder networks
with slanted bypasses, which break the fore-aft structural symmetry. Our
analytical results indicate that unlike symmetric ladder networks, structural
asymmetry introduced by a single slanted bypass can be used to modulate the
relative drop spacing, enabling them to contract, synchronize, expand, or even
flip at the ladder exit. Our experiments confirm all these behaviors predicted
by theory. Numerical analysis further shows that while ladder networks
containing several identical bypasses are limited to nearly linear
transformation of input delay between drops, mixed combination of bypasses can
cause significant non-linear transformation enabling coding and decoding of
input delays.Comment: 4 pages, 5 figure
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