20 research outputs found
ALE spaces from noncommutative U(1) instantons via exact Seiberg-Witten map
The exact Seiberg-Witten (SW) map of a noncommutative (NC) gauge theory gives
the commutative equivalent as an ordinary gauge theory coupled to a field
dependent effective metric. We study instanton solutions of this commutative
equivalent whose self-duality equation turns out to be the exact SW map of NC
instantons. We derive general differential equations governing U(1) instantons
and we explicitly get an exact solution corresponding to the single NC
instanton. Remarkably the effective metric induced by the single U(1) instanton
is related to the Eguchi-Hanson metric - the simplest gravitational instanton.
Surprisingly the instanton number is not quantized but depends on an
integration constant. Our result confirms the expected non-perturbative
breakdown of the SW map. However, the breakdown of the map arises in a
consistent way: The instanton number plays the role of a parameter giving rise
to a one-parameter family of Eguchi-Hanson metrics.Comment: 15 pages, Latex; Comment on commutative limit is added and a small
mistake in section 4 is correcte
The one-loop effective action of noncommutative {\cal N}=4 super Yang-Mills is gauge invariant
We study the gauge transformation of the recently computed one-loop
four-point function of {\cal N}=4 supersymmetric Yang-Mills theory with gauge
group U(N). The contributions from nonplanar diagrams are not gauge invariant.
We compute their gauge variation and show that it is cancelled by the variation
from corresponding terms of the one-loop five-point function. This mechanism is
general: it insures the gauge invariance of the noncommutative one-loop
effective action.Comment: LaTex, 13 pages, 4 figure
The Efficacy of a Bilateral Approach for Treating Lesions With Chronic Total Occlusions The CART (Controlled Antegrade and Retrograde subintimal Tracking) Registry
ObjectivesThe aim of this study was to evaluate the safety and feasibility of a new concept for chronic total occlusion (CTO) recanalization—using a bilateral approach that utilizes a Controlled Antegrade and Retrograde subintimal Tracking (CART) technique.BackgroundSuccessful percutaneous recanalization of coronary CTOs results in improved long-term outcomes. The recanalization of CTOs in native coronary arteries no doubt represents one of the most technically challenging of interventional procedures.MethodsA total of 224 consecutive patients (mean age 61 ± 9 years; 86.2% men) were enrolled in this prospective multicenter registry. This technique combines the simultaneous use of antegrade and retrograde approaches. A subintimal dissection is created in both antegrade and retrograde fashion, thereby limiting the extension of the subintimal dissection within the CTO portion.ResultsOf 224 CTO lesions (>3 months in duration) undergoing attempted recanalization using the CART technique, 145 cases (64.7%) had undergone previous CTO recanalization attempts. The success rates of crossing in a retrograde fashion with a wire and a balloon were 87.9% and 79.9%, respectively. The overall technical and procedural success rates achieved in this registry were 92.4% and 90.6%, respectively.ConclusionsA bilateral approach for CTO lesions using the CART technique is feasible, safe, and has a higher success rate than previous approaches. These results indicate that a bilateral technique can solve a major dilemma that commonly affects CTO procedures
IL-1β Suppresses Innate IL-25 and IL-33 Production and Maintains Helminth Chronicity.
Approximately 2 billion people currently suffer from intestinal helminth infections, which are typically chronic in nature and result in growth retardation, vitamin A deficiency, anemia and poor cognitive function. Such chronicity results from co-evolution between helminths and their mammalian hosts; however, the molecular mechanisms by which these organisms avert immune rejection are not clear. We have found that the natural murine helminth, Heligmosomoides polygyrus bakeri (Hp) elicits the secretion of IL-1β in vivo and in vitro and that this cytokine is critical for shaping a mucosal environment suited to helminth chronicity. Indeed in mice deficient for IL-1β (IL-1β(-/-)), or treated with the soluble IL-1βR antagonist, Anakinra, helminth infection results in enhanced type 2 immunity and accelerated parasite expulsion. IL-1β acts to decrease production of IL-25 and IL-33 at early time points following infection and parasite rejection was determined to require IL-25. Taken together, these data indicate that Hp promotes the release of host-derived IL-1β that suppresses the release of innate cytokines, resulting in suboptimal type 2 immunity and allowing pathogen chronicity
Consensus standards for acquisition, measurement, and reporting of intravascular optical coherence tomography studies
Objectives: The purpose of this document is to make the output of the International Working Group for Intravascular Optical Coherence Tomography (IWG-IVOCT) Standardization and Validation available to medical and scientific communities, through a peer-reviewed publication, in the interest of improving the diagnosis and treatment of patients with atherosclerosis, including coronary artery disease. Background: Intravascular optical coherence tomography (IVOCT) is a catheter-based modality that acquires images at a resolution of ∼10 μm, enabling visualization of blood vessel wall microstructure in vivo at an unprecedented level of detail. IVOCT devices are now commercially available worldwide, there is an active user base, and the interest in using this technology is growing. Incorporation of IVOCT in research and daily clinical practice can be facilitated by the development of uniform terminology and consensus-based standards on use of the technology, interpretation of the images, and reporting of IVOCT results. Methods: The IWG-IVOCT, comprising more than 260 academic and industry members from Asia, Europe, and the United States, formed in 2008 and convened on the topic of IVOCT standardization through a series of 9 national and international meetings. Results: Knowledge and recommendations from this group on key areas within the IVOCT field were assembled to generate this consensus document, authored by the Writing Committee, composed of academicians who have participated in meetings and/or writing of the text. Conclusions: This document may be broadly used as a standard reference regarding the current state of the IVOCT imaging modality, intended for researchers and clinicians who use IVOCT and analyze IVOCT data
Coulomb dissociation of N 20,21
Neutron-rich light nuclei and their reactions play an important role in the creation of chemical elements. Here, data from a Coulomb dissociation experiment on N20,21 are reported. Relativistic N20,21 ions impinged on a lead target and the Coulomb dissociation cross section was determined in a kinematically complete experiment. Using the detailed balance theorem, the N19(n,γ)N20 and N20(n,γ)N21 excitation functions and thermonuclear reaction rates have been determined. The N19(n,γ)N20 rate is up to a factor of 5 higher at
Condicionamento em pós-colheita de <i>Etlingera</i> <i>elatior</i> (Jack) R. M. Smith
Este trabalho teve como objetivo estudar a longevidade de hastes de E. elatior variedades Red Torch (vermelha) e Pink Torch (rosa), após imersão em solução de condicionamento