263 research outputs found
The Seiberg-Witten Map for Noncommutative Gauge Theories
The Seiberg-Witten map for noncommutative Yang-Mills theories is studied and
methods for its explicit construction are discussed which are valid for any
gauge group. In particular the use of the evolution equation is described in
some detail and its relation to the cohomological approach is elucidated.
Cohomological methods which are applicable to gauge theories requiring the
Batalin-Vilkoviskii antifield formalism are briefly mentioned. Also, the
analogy of the Weyl-Moyal star product with the star product of open bosonic
string field theory and possible ramifications of this analogy are briefly
mentioned.Comment: 12 pages, talk presented at "Continuous Advances in QCD
2002/Arkadyfest", University of Minnesota, Minneapolis, May 17-23, 2002. A
few misprints correcte
A Cohomological Approach to the Non-Abelian Seiberg-Witten Map
We present a cohomological method for obtaining the non-Abelian
Seiberg-Witten map for any gauge group and to any order in theta. By
introducing a ghost field, we are able to express the equations defining the
Seiberg-Witten map through a coboundary operator, so that they can be solved by
constructing a corresponding homotopy operator.Comment: 18 pages. References added and some misprints correcte
Role of Carbonate in the Cytotoxicity of Carboplatin
Carboplatin, [Pt(NH3)2(CBDCA-O,O\u27)], 1, where CBDCA is cyclobutane-1,1-dicarboxylate, is used against ovarian, lung, and other types of cancer. We recently showed (Di Pasqua et al. (2006) Chem. Res. Toxicol. 19, 139-149) that carboplatin reacts with carbonate under conditions that simulate therapy to produce carbonato carboplatin, cis-[Pt(NH3)2(O-CBDCA)(CO3)]2-, 2. We use 13C and 1H NMR and UV-visible absorption spectroscopy to show that solutions containing carboplatin that have been aged in carbonate buffer under various conditions contain 1, 2, and other compounds. We then show that aging carboplatin in carbonate produces compounds that are more toxic to human neuroblastoma (SK-N-SH), proximal renal tubule (HK-2) and Namalwa-luc Burkitt\u27s lymphoma (BL) cells than carboplatin alone. Moreover, increasing the aging time increases the cytotoxicity of the platinum solutions as measured by the increase in cell death. Although HK-2 cells experience a large loss in survival upon exposure to carbonato forms of the drug, they have the highest values of IC50 of the three cell lines studied, so that HK-2 cells remain the most resistant to the toxic effects of the carbonato forms in the culture medium. This is consistent with the well-known low renal toxicity observed for carboplatin in therapy. The uptake rates for normal Jurkat cells (NJ) and cisplatin-resistant Jurkat cells (RJ), measured by inductively coupled plasma mass spectrometry (ICP-MS), are 16.6 +/- 4.2 and 12.3 +/- 4.8 amol of Pt h-1 cell-1, respectively, when exposed to carboplatin alone. However, when these cells are exposed to carboplatin that has been aged in carbonate media, normal Jurkat cells strongly bind/take up Pt at a rate of 14.5 +/- 4.1 amol of Pt h-1 cell-1, while resistant cells strongly bind/take up 5.1 +/- 3.3 amol of Pt h-1 cell-1. Collectively, these studies show that carboplatin carbonato species may play a major role in the cytotoxicity and uptake of carboplatin by cells
Analysis of boundary layer sounding data from the FIRE Marine Stratocumulus Project
October 1987.FIRE volume 2 on cover.Includes bibliographical references.We present an analysis of the boundary layer thermodynamic data obtained by the CLASS radiosonde system during the marine boundary layer experiment on San Nicolas Island in the summer of 1987. The analysis procedure retains the highest possible vertical resolution in the data. Plots of temperature, dew point temperature, potential temperature, equivalent potential temperature and saturation equivalent potential temperature are presented for each of the sixty-nine soundings taken during FIRE. Conditions were mostly cloudy with fifty-five of the sixty-nine soundings being released with stratocumulus overhead. For the fifty-live cloudy soundings, cloud top Jumps of equivalent potential temperature i, and total water mixing ratio r were also determined. Each of these soundings is then represented by a point in the (~11., ~r) plane. Fifteen of these soundings are on the unstable aide of the evaporative instability line, and there appears to be some tendency for break-up under these conditions
CSU data set of the FIRE marine stratocumulus IFO, The
August 1988.Includes bibliographical references.This research was funded by NASA under grant NAG 1-554 and by ONR under grant N00014-87-K-0228/P00001
CSU tethered balloon data set of the FIRE marine stratocumulus IFO, The
November, 1988.Includes bibliographical references.Funding agencies: National Aeronautics and Space Administration, Office of Naval Research. This research was funded by ONR under grant N00014-87-K-0228/P00001 and by NASA under grant NAG 1-554
Phenotypical and molecular assessment of the virulence potential of KPC-3-producing Klebsiella pneumoniae ST392 clinical isolates
Klebsiella pneumoniae is a Gram-negative bacterium of clinical importance, due to its resistance to several antibiotic classes. We have identified 4 clinical isolates of K. pneumoniae sequence type (ST) 392 KPC-3-producing strains from patients at the Istituto Mediterraneo per i Trapianti e Terapie ad Alta Specializzazione (IRCCS-ISMETT), a Southern Italian transplantation health facility, during a routine surveillance for carbapenemase-producing Enterobacterales from in-house clinical samples. Since those were among, to the best of our knowledge, the first KPC-producing K. pneumoniae ST392 isolated in Europe, we assessed their virulence potential, to understand if this particular ST can become an endemic clinical threat. ST392 isolates were investigated to assess their virulence potential, namely resistance to human sera, formation of abiotic biofilms, adhesion to biotic surfaces, exopolysaccharide production and in vivo pathogenesis in the wax moth Galleria mellonella animal model. ST392-belonging strains were highly resistant to human sera. These strains also have a high capacity to form abiotic biofilms and high levels of adhesion to the human epithelial colorectal adenocarcinoma HT-29 cell line. An increase of transcriptional levels of genes involved in serum resistance (aroE and traT) and adhesion (pgaA) was observed when compared with the Klebsiella quasipneumoniae subsp. similipneumoniae strain ATCC 700603 reference strain. Infection of G. mellonella larvae with ST392 clinical isolates showed that the latter were not highly pathogenic in this model. Together, our results indicate that ST392 isolates have the potential to become a strain of clinical relevance, especially in health settings where patients are immunosuppressed, e.g., transplant recipients
Organogenesis and embryogenesis in several hypericum perforatum genotypes
St John’s wort (Hypericum perforatum) is a valuable plant used as a herbal remedy or in phytopharmaceutical drugs to
treat a variety of physical ailments. Much research has been performed to study the biochemical production of secondary
metabolites of in vitro cultured plants or organs. However, all of these studies have looked at the regeneration of plants
from explants in only one genotype. In addition, no study has revealed the mechanism of plant regeneration in
H. perforatum, i.e. organogenesis or somatic embryogenesis. We found that different genotypes Helos, Topas, Elixir, and
Numi responded similarly to regeneration medium. The regeneration responses (i.e. callus, root, or shoot production) of
identical explants from different genotypes were similar. However, the source of explant material (leaves, hypocotyls, and
roots) from the same genotype had significant effects on the response to media and plant regeneration frequency. Using
scanning electron microscopy and light microscopy, the progress of organogenesis and embryogenesis under similar
culture conditions was recorded. Root segments were the most responsive explants, producing the maximum number of
shoots per explant of all the genotypes.Fundação para a Ciência e a Tecnologia (FCT) -
POCTI/AGR/40 283/2001, SFRH/BPD/17102/2004
Interacting Ricci Dark Energy with Logarithmic Correction
Motivated by the holographic principle, it has been suggested that the dark
energy density may be inversely proportional to the area of the event
horizon of the universe. However, such a model would have a causality problem.
In this work, we consider the entropy-corrected version of the holographic dark
energy model in the non-flat FRW universe and we propose to replace the future
event horizon area with the inverse of the Ricci scalar curvature. We obtain
the equation of state (EoS) parameter , the deceleration
parameter and in the presence of interaction between Dark
Energy (DE) and Dark Matter (DM). Moreover, we reconstruct the potential and
the dynamics of the tachyon, K-essence, dilaton and quintessence scalar field
models according to the evolutionary behavior of the interacting
entropy-corrected holographic dark energy model.Comment: 24 pages, accepted for publication in 'Astrophysics and Space
Science, DOI:10.1007/s10509-012-1031-8
Hypericum perforatum plant cells reduce Agrobacterium viability during co-cultivation
Plant recalcitrance is the major barrier in developing Agrobacterium-mediated transformation protocols for several important plant species. Despite the substantial knowledge of T-DNA transfer process, very little is known about the factors leading to the plant recalcitrance. Here, we analyzed the basis of Hypericum perforatum L. (HP) recalcitrance to Agrobacterium-mediated transformation using cell suspension culture. When challenged with Agrobacterium, HP cells swiftly produced an intense oxidative burst, a typical reaction of plant defense. Agrobacterium viability started to decline and reached 99% mortality within 12Â h, while the plant cells did not suffer apoptotic process. This is the first evidence showing that the reduction of Agrobacterium viability during co-cultivation with recalcitrant plant cells can affect transformation
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