92 research outputs found
Analytic Expressions for Singular Vectors of the Superconformal Algebra
Using explicit expressions for a class of singular vectors of the
(untwisted) algebra and following the approach of Malikov-Feigin-Fuchs and
Kent, we show that the analytically extended Verma modules contain two linearly
independent neutral singular vectors at the same grade. We construct this two
dimensional space and we identify the singular vectors of the original Verma
modules. We show that in some Verma modules these expressions lead to two
linearly independent singular vectors which are at the same grade and have the
same charge.Comment: 35 pages, LATE
Multiloop Superstring Amplitudes from Non-Minimal Pure Spinor Formalism
Using the non-minimal version of the pure spinor formalism, manifestly
super-Poincare covariant superstring scattering amplitudes can be computed as
in topological string theory without the need of picture-changing operators.
The only subtlety comes from regularizing the functional integral over the pure
spinor ghosts. In this paper, it is shown how to regularize this functional
integral in a BRST-invariant manner, allowing the computation of arbitrary
multiloop amplitudes. The regularization method simplifies for scattering
amplitudes which contribute to ten-dimensional F-terms, i.e. terms in the
ten-dimensional superspace action which do not involve integration over the
maximum number of 's.Comment: 23 pages harvmac, added acknowledgemen
Anterior minimally invasive extrapleural retroperitoneal approach to the thoraco-lumbar junction of the spine
SummaryBackgroundThe anterior approach to the thoraco-lumbar junction of the spine allows therapeutic interventions on post-traumatic, infectious, and neoplastic vertebral lesions from T11 to L2 combining spinal cord decompression, corporectomy, and vertebral body fusion. However, this approach also has a reputation for damaging the intervening anatomic structures (lungs, peritoneum, and diaphragm). The objective of this study was to show that both nervous structure decompression and anterior vertebral reconstruction can be achieved via an anterior minimally invasive extrapleural retroperitoneal (AMIER) approach.MaterialWe describe each of the steps of the AMIER approach to the thoraco-lumbar junction of the spine.ResultsThe AMIER approach ensures excellent exposure that allows full decompression and satisfactory anterior anatomic reconstruction. The main difficulties and complications relate to the lungs, and a painstaking and rigorous technique limits the complications compared to conventional thoraco-phreno-lumbotomy
Rationality of Bershadsky-Polyakov vertex algebras
We prove the conjecture of Kac-Wakimoto on the rationality of exceptional
W-algebras for the first non-trivial series, namely, for the
Bershadsky-Polyakov vertex algebras at level with
. This gives new examples of rational conformal field theories.Comment: To appear in Comm. Math. Phy
Unitarity of rational N=2 superconformal theories
We demonstrate that all rational models of the N=2 super Virasoro algebra are
unitary. Our arguments are based on three different methods: we determine Zhu's
algebra (for which we give a physically motivated derivation) explicitly for
certain theories, we analyse the modular properties of some of the vacuum
characters, and we use the coset realisation of the algebra in terms of su_2
and two free fermions.
Some of our arguments generalise to the Kazama-Suzuki models indicating that
all rational N=2 supersymmetric models might be unitary.Comment: LaTeX (+amssym.def), 28 pages; minor changes in content, some
references added, final versio
On the six-dimensional origin of the AGT correspondence
We argue that the six-dimensional (2,0) superconformal theory defined on M
\times C, with M being a four-manifold and C a Riemann surface, can be twisted
in a way that makes it topological on M and holomorphic on C. Assuming the
existence of such a twisted theory, we show that its chiral algebra contains a
W-algebra when M = R^4, possibly in the presence of a codimension-two defect
operator supported on R^2 \times C \subset M \times C. We expect this structure
to survive the \Omega-deformation.Comment: References added. 14 page
Gepner-like models and Landau-Ginzburg/sigma-model correspondence
The Gepner-like models of -type is considered. When is multiple
of the elliptic genus and the Euler characteristic is calculated. Using
free-field representation we relate these models with -models on
hypersurfaces in the total space of anticanonical bundle over the projective
space
Analysis of the feasibility of reducing fuel consumption and carbon-dioxide emissions and obtaining carbon credits with the use of sverdlovskaya-oblast factories as an example
This article discusses aspects of improving the efficiency of heating and heat-treatment furnaces from the standpoint of the fuel savings that can be realized by the use of different methods to modernize such furnaces. © 2013 Springer Science+Business Media New York
In vitro antioxidant and anticancer activity of young Zingiber officinale against human breast carcinoma cell lines
<p>Abstract</p> <p>Background</p> <p>Ginger is one of the most important spice crops and traditionally has been used as medicinal plant in Bangladesh. The present work is aimed to find out antioxidant and anticancer activities of two Bangladeshi ginger varieties (Fulbaria and Syedpuri) at young age grown under ambient (400 μmol/mol) and elevated (800 μmol/mol) CO<sub>2 </sub>concentrations against two human breast cancer cell lines (MCF-7 and MDA-MB-231).</p> <p>Methods</p> <p>The effects of ginger on MCF-7 and MDA-MB-231 cell lines were determined using TBA (thiobarbituric acid) and MTT [3-(4,5-dimethylthiazolyl)-2,5-diphenyl-tetrazolium bromide] assays. Reversed-phase HPLC was used to assay flavonoids composition among Fulbaria and Syedpuri ginger varieties grown under increasing CO<sub>2 </sub>concentration from 400 to 800 μmol/mol.</p> <p>Results</p> <p>Antioxidant activities in both varieties found increased significantly (P ≤ 0.05) with increasing CO<sub>2 </sub>concentration from 400 to 800 μmol/mol. High antioxidant activities were observed in the rhizomes of Syedpuri grown under elevated CO<sub>2 </sub>concentration. The results showed that enriched ginger extract (rhizomes) exhibited the highest anticancer activity on MCF-7 cancer cells with IC<sub>50 </sub>values of 34.8 and 25.7 μg/ml for Fulbaria and Syedpuri respectively. IC<sub>50 </sub>values for MDA-MB-231 exhibition were 32.53 and 30.20 μg/ml for rhizomes extract of Fulbaria and Syedpuri accordingly.</p> <p>Conclusions</p> <p>Fulbaria and Syedpuri possess antioxidant and anticancer properties especially when grown under elevated CO<sub>2 </sub>concentration. The use of ginger grown under elevated CO<sub>2 </sub>concentration may have potential in the treatment and prevention of cancer.</p
Standard of civilization, nomadism and territoriality in nineteenth-century international society
In this chapter, the encounter between the Russian Empire and the nomads of the Eurasian steppe in the nineteenth century is analyzed using the theoretical framework of the standard of civilization. The creation of the Westphalian state-model in Europe in the seventeenth century, linked to the later emergence of the notion of the standard of civilization led to the ‘othering’ of the nomads of the Eurasian steppe as barbarians, as a threat to the borders of civilized Europe. The chapter presents also an argument to define ‘territoriality’ as not only an institution of international society of the time but also as a distinctive quality and requirement for being considered ‘civilized’. In this analytical framework, the nomads become the ‘other’, the ‘alien’, the ‘menace’, onto which projections of rationality and modernity were cast in order to prevent threats to Russia’s European and civilized identity. The chapter sheds light on the encounter between ‘fixed’ and ‘mobile’ units in the course of expansion of international society; contextualizes the role played by nomadic tribes in resisting the application of Westphalian spatial categories in the Eurasian space; and scrutinizes what the role of nomads was in constructing a European, civilized identity.PostprintPeer reviewe
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