395 research outputs found
Classical r-matrix of the su(2|2) SYM spin-chain
In this note we straightforwardly derive and make use of the quantum R-matrix
for the su(2|2) SYM spin-chain in the manifest su(1|2)-invariant formulation,
which solves the standard quantum Yang-Baxter equation, in order to obtain the
correspondent (undressed) classical r-matrix from the first order expansion in
the ``deformation'' parameter 2 \pi / \sqrt{\lambda}, and check that this last
solves the standard classical Yang-Baxter equation. We analyze its bialgebra
structure, its dependence on the spectral parameters and its pole structure. We
notice that it still preserves an su(1|2) subalgebra, thereby admitting an
expression in terms of a combination of projectors, which spans only a subspace
of su(1|2) \otimes su(1|2). We study the residue at its simple pole at the
origin, and comment on the applicability of the classical Belavin-Drinfeld type
of analysis.Comment: 14 pages, LaTeX, no figures; corrections made, further analysis of
the residue and references adde
Two-loop Integrability of Planar N=6 Superconformal Chern-Simons Theory
Bethe ansatz equations have been proposed for the asymptotic spectral problem
of AdS_4/CFT_3. This proposal assumes integrability, but the previous
verification of weak-coupling integrability covered only the su(4) sector of
the ABJM gauge theory. Here we derive the complete planar two-loop dilatation
generator of N=6 superconformal Chern-Simons theory from osp(6|4)
superconformal symmetry. For the osp(4|2) sector, we prove integrability
through a Yangian construction. We argue that integrability extends to the full
planar two-loop dilatation generator, confirming the applicability of the Bethe
equations at weak coupling. Further confirmation follows from an analytic
computation of the two-loop twist-one spectrum.Comment: 45 pages, v2: typos in (D.9) fixed, reference added, many small
change
From Scattering Amplitudes to the Dilatation Generator in N=4 SYM
The complete spin chain representation of the planar N=4 SYM dilatation
generator has long been known at one loop, where it involves leading
nearest-neighbor 2 -> 2 interactions. In this work we use superconformal
symmetry to derive the unique solution for the leading L -> 2 interactions of
the planar dilatation generator for arbitrarily large L. We then propose that
these interactions are given by the scattering operator that has N=4 SYM
tree-level scattering amplitudes as matrix elements. We provide compelling
evidence for this proposal, including explicit checks for L=2,3 and a proof of
consistency with superconformal symmetry.Comment: 39 pages, v2: reference added and minor changes, published versio
Alpha scattering and capture reactions in the A = 7 system at low energies
Differential cross sections for He- scattering were measured in
the energy range up to 3 MeV. These data together with other available
experimental results for He and H scattering were
analyzed in the framework of the optical model using double-folded potentials.
The optical potentials obtained were used to calculate the astrophysical
S-factors of the capture reactions HeBe and
HLi, and the branching ratios for the transitions into
the two final Be and Li bound states, respectively. For
HeBe excellent agreement between calculated and
experimental data is obtained. For HLi a value
has been found which is a factor of about 1.5 larger than the adopted value.
For both capture reactions a similar branching ratio of has been obtained.Comment: submitted to Phys.Rev.C, 34 pages, figures available from one of the
authors, LaTeX with RevTeX, IK-TUW-Preprint 930540
Vorinostat in advanced prostate cancer patients progressing on prior chemotherapy (National Cancer Institute Trial 6862)
BACKGROUND: This phase 2 trial was designed to evaluate the efficacy of vorinostat in chemotherapy-pretreated patients with metastatic castration-resistant prostate cancer. METHODS: Patients with disease progression on 1 prior chemotherapy, a prostate-specific antigen (PSA) ≥5 ng/mL, and adequate organ function were treated with 400 mg vorinostat orally daily. The primary endpoint was the 6-month progression rate. Secondary endpoints included safety, rate of PSA decline, objective response, overall survival, and effects of vorinostat on serum interleukin-6 (IL-6) levels. RESULTS: Twenty-seven eligible patients were accrued. The median number of cycles delivered was 2 (range, 1-7). All patients were taken off therapy before 6 months. The best objective response in the eligible patient was stable disease in 2 (7%) patients. No PSA decline of ≥50% was observed. There was 1 grade 4 adverse event (AE), and 44% of patients experienced grade 3 adverse events. The most common adverse events were fatigue (81%), nausea (74%), anorexia (59%), vomiting (33%), diarrhea (33%), and weight loss (26%). Median time to progression and overall survival were 2.8 and 11.7 months, respectively. Median IL-6 levels (pg/mL) were higher in patients removed from the protocol for toxicity compared with progression at all time points, including baseline (5.2 vs 2.1, P = .02), Day 15 Cycle 1 (9.5 vs 2.2, P = .01), Day 1 Cycle 2 (9.8 vs 2.2, P = .01), and end of study (11.0 vs 2.9, P = .09). CONCLUSIONS: Vorinostat at this dose was associated with significant toxicities limiting efficacy assessment in this patient population. The significant association between IL-6 levels and removal from the study for toxicities warrants further investigation. Cancer 2009. © 2009 American Cancer Society.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/64445/1/24597_ftp.pd
N=4 SYM to Two Loops: Compact Expressions for the Non-Compact Symmetry Algebra of the su(1,1|2) Sector
We begin a study of higher-loop corrections to the dilatation generator of
N=4 SYM in non-compact sectors. In these sectors, the dilatation generator
contains infinitely many interactions, and therefore one expects very
complicated higher-loop corrections. Remarkably, we find a short and simple
expression for the two-loop dilatation generator. Our solution for the
non-compact su(1,1|2) sector consists of nested commutators of four O(g)
generators and one simple auxiliary generator. Moreover, the solution does not
require the planar limit; we conjecture that it is valid for any gauge group.
To obtain the two-loop dilatation generator, we find the complete O(g^3)
symmetry algebra for this sector, which is also given by concise expressions.
We check our solution using published results of direct field theory
calculations. By applying the expression for the two-loop dilatation generator
to compute selected anomalous dimensions and the bosonic sl(2) sector internal
S-matrix, we confirm recent conjectures of the higher-loop Bethe ansatz of
hep-th/0412188.Comment: 28 pages, v2: additional checks against direct field theory
calculations, references added, minor corrections, v3: additional minor
correction
Association of Complement and MAPK Activation With SARS-CoV-2-Associated Myocardial Inflammation
IMPORTANCE Myocardial injury is a common feature of patients with SARS-CoV-2 infection. However, the cardiac inflammatory processes associated with SARS-CoV-2 infection are not completely understood. OBJECTIVE To investigate the inflammatory cardiac phenotype associated with SARS-CoV-2 infection compared with viralmyocarditis, immune-mediatedmyocarditis, and noninflammatory cardiomyopathy by integrating histologic, transcriptomic, and proteomic profiling. DESIGN, SETTING, AND PARTICIPANTS This case serieswas a cooperative study between the Ludwig Maximilian University Hospital Munich and the Cardiopathology Referral Center at the University of Tubingen in Germany. A cohort of 19 patients with suspectedmyocarditis was examined; of those, 5 patients were hospitalized with SARS-CoV-2 infection between March and May 2020. Cardiac tissue specimens from those 5 patients were compared with specimens from 5 patients with immune-mediatedmyocarditis, 4 patients with non-SARS-CoV-2 viralmyocarditis, and 5 patients with noninflammatory cardiomyopathy, collected from January to August 2019. EXPOSURES Endomyocardial biopsy. MAIN OUTCOMES AND MEASURES The inflammatory cardiac phenotypeswere measured by immunohistologic analysis, RNA exome capture sequencing, and mass spectrometry-based proteomic analysis of endomyocardial biopsy specimens. RESULTS Among 19 participants, the median age was 58 years (range, 37-76 years), and 15 individuals (79%) were male. Data on race and ethnicity were not collected. The abundance of CD163+ macrophages was generally higher in the cardiac tissue of patients with myocarditis, whereas lymphocyte counts were lower in the tissue of patients with SARS-CoV-2 infection vs patients with non-SARS-CoV-2 virus-associated and immune-mediatedmyocarditis. Among those with SARS-CoV-2 infection, components of the complement cascade, including C1q subunits (transcriptomic analysis: 2.5-fold to 3.6-fold increase; proteomic analysis: 2.0-fold to 3.4-fold increase) and serine/cysteine proteinase inhibitor clade G member 1 (transcriptomic analysis: 1.7-fold increase; proteomic analysis: 2.6-fold increase), belonged to the most commonly upregulated transcripts and differentially abundant proteins. In cardiac macrophages, the abundance of C1q was highest in SARS-CoV-2 infection. Assessment of important signaling cascades identified an upregulation of the serine/threonine mitogen-activated protein kinase pathways. CONCLUSIONS AND RELEVANCE This case series found that the cardiac immune signature varied in inflammatory conditions with different etiologic characteristics. Future studies are needed to examine the role of these immune pathways inmyocardial inflammation
Degenerate Rotating Black Holes, Chiral CFTs and Fermi Surfaces I - Analytic Results for Quasinormal Modes
In this work we discuss charged rotating black holes in
that degenerate to extremal black holes with zero entropy. These black holes
have scaling properties between charge and angular momentum similar to those of
Fermi surface operators in a subsector of SYM. We add a
massless uncharged scalar to the five dimensional supergravity theory, such
that it still forms a consistent truncation of the type IIB ten dimensional
supergravity and analyze its quasinormal modes. Separating the equation of
motion to a radial and angular part, we proceed to solve the radial equation
using the asymptotic matching expansion method applied to a Heun equation with
two nearby singularities. We use the continued fraction method for the angular
Heun equation and obtain numerical results for the quasinormal modes. In the
case of the supersymmetric black hole we present some analytic results for the
decay rates of the scalar perturbations. The spectrum of quasinormal modes
obtained is similar to that of a chiral 1+1 CFT, which is consistent with the
conjectured field-theoretic dual. In addition, some of the modes can be found
analytically.Comment: 41 pages, 1 figure, LaTeX; v2: typos corrected, references adde
Yangian symmetry of scattering amplitudes in N=4 super Yang-Mills theory
Tree-level scattering amplitudes in N=4 super Yang-Mills theory have recently
been shown to transform covariantly with respect to a 'dual' superconformal
symmetry algebra, thus extending the conventional superconformal symmetry
algebra psu(2,2|4) of the theory. In this paper we derive the action of the
dual superconformal generators in on-shell superspace and extend the dual
generators suitably to leave scattering amplitudes invariant. We then study the
algebra of standard and dual symmetry generators and show that the inclusion of
the dual superconformal generators lifts the psu(2,2|4) symmetry algebra to a
Yangian. The non-local Yangian generators acting on amplitudes turn out to be
cyclically invariant due to special properties of psu(2,2|4). The
representation of the Yangian generators takes the same form as in the case of
local operators, suggesting that the Yangian symmetry is an intrinsic property
of planar N=4 super Yang-Mills, at least at tree level.Comment: 23 pages, no figures; v2: typos corrected, references added; v3:
minor changes, references adde
Long-Range Deformations for Integrable Spin Chains
We present a recursion relation for the explicit construction of integrable
spin chain Hamiltonians with long-range interactions. Based on arbitrary
short-range (e.g. nearest-neighbor) integrable spin chains, it allows to
construct an infinite set of conserved long-range charges. We explain the
moduli space of deformation parameters by different classes of generating
operators. The rapidity map and dressing phase in the long-range Bethe
equations are a result of these deformations. The closed chain asymptotic Bethe
equations for long-range spin chains transforming under a generic symmetry
algebra are derived. Notably, our construction applies to generalizations of
standard nearest-neighbor chains such as alternating spin chains. We also
discuss relevant properties for its application to planar D=4, N=4 and D=3, N=6
supersymmetric gauge theories. Finally, we present a map between long-range and
inhomogeneous spin chains delivering more insight into the structures of these
models as well as their limitations at wrapping order.Comment: 63 pages, v2: references added, v3: typos corrected in eqs (8.20) and
(8.24
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