242 research outputs found
Half-Monopole and Multimonopole
We would like to present some exact SU(2) Yang-Mills-Higgs monopole solutions
of half-integer topological charge. These solutions can be just an isolated
half-monopole or a multimonopole with topological magnetic charge, ,
where is a natural number. These static monopole solutions satisfy the
first order Bogomol'nyi equations. The axially symmetric one-half monopole
gauge potentials possess a Dirac-like string singularity along the negative
z-axis. The multimonopole gauge potentials are also singular along the z-axis
and possess only mirror symmetries.Comment: 12 pages and 4 figures; typos corrected, reference adde
Sphingosine 1-Phosphate: A Novel Target for Lung Disorders
Sphingosine 1-phosphate (S1P) is involved in a wide range of cellular processes, which include proliferation, apoptosis, lymphocyte egress, endothelial barrier function, angiogenesis, and inflammation. S1P is produced by two isoenzymes, namely, sphingosine kinase 1 and 2 (SphK1 and 2) and once produced, S1P can act both in an autocrine and paracrine manner. S1P can be dephosphorylated back to sphingosine by two phosphatases (SGPP 1 and 2) or can be irreversibly cleaved by S1P lyase. S1P has a diverse range of functions, which is mediated in a receptor dependent, through G-protein coupled receptors (S1PR1–5) or receptor independent manner, through intracellular targets such as HDACs and TRAF2. The involvement of S1P signaling has been confirmed in various disease conditions including lung diseases. The SphK inhibitors and S1PR modulators are currently under clinical trials for different pathophysiological conditions. There is a significant effort in targeting various components of S1P signaling for several diseases. This review focuses on the ways in which S1P signaling can be therapeutically targeted in lung disorders
Nitrogen-containing carbon nanotubes
Carbon nanotubes containing small amounts of nitrogen are produced by the pyrolysis of aza-aromatics such as pyridine, methylpyrimidine and triazine over cobalt nanoparticles in an Ar atmosphere; good yields of such nanotubes are obtained by carrying out the pyrolysis of a mixture of pyridine and Fe(CO)5 in flowing Ar+H2
Abelian 2-form gauge theory: special features
It is shown that the four -dimensional (4D) free Abelian 2-form
gauge theory provides an example of (i) a class of field theoretical models for
the Hodge theory, and (ii) a possible candidate for the quasi-topological field
theory (q-TFT). Despite many striking similarities with some of the key
topological features of the two -dimensional (2D) free Abelian (and
self-interacting non-Abelian) gauge theories, it turns out that the 4D free
Abelian 2-form gauge theory is {\it not} an exact TFT. To corroborate this
conclusion, some of the key issues are discussed. In particular, it is shown
that the (anti-)BRST and (anti-)co-BRST invariant quantities of the 4D 2-form
Abelian gauge theory obey the recursion relations that are reminiscent of the
exact TFTs but the Lagrangian density of this theory is not found to be able to
be expressed as the sum of (anti-)BRST and (anti-)co-BRST exact quantities as
is the case with the {\it topological} 2D free Abelian (and self-interacting
non-Abelian) gauge theories.Comment: LaTeX, 23 pages, journal ref. give
Area spectra versus entropy spectra in black holes in topologically massive gravity
We consider the area and entropy spectra of black holes in topologically
massive gravity with gravitational Chern-Simons term. The examples we consider
are the BTZ black hole and the warped AdS black hole. For the non-rotating BTZ
black hole, the area and entropy spectra are equally spaced and independent of
the coupling constant \v of the Chern-Simons term. For the rotating BTZ black
hole case, the spectra of the inner and outer horizon areas are not equally
spaced in general and dependent of the coupling constant \v. However the
entropy spectrum is equally spaced and independent of the coupling constant
\v. For the warped AdS black holes for by using the quasinormal modes
obtained without imposing the boundary condition at radial infinity we find
again that the entropy spectrum is equally spaced and independent of the
coupling constant \v, while the spectra of the inner and outer horizon areas
are not equally spaced and dependent of the coupling constant \v. Our result
implies that the entropy spectrum has a universal behavior regardless of the
presence of the gravitational Chern-Simons term, and therefore it implies that
the entropy is more `fundamental' than the horizon area.Comment: 16 page
Notoph Gauge Theory: Superfield Formalism
We derive absolutely anticommuting Becchi-Rouet-Stora-Tyutin (BRST) and
anti-BRST symmetry transformations for the 4D free Abelian 2-form gauge theory
by exploiting the superfield approach to BRST formalism. The antisymmetric
tensor gauge field of the above theory was christened as the "notoph" (i.e. the
opposite of "photon") gauge field by Ogievetsky and Palubarinov way back in
1966-67. We briefly outline the problems involved in obtaining the absolute
anticommutativity of the (anti-) BRST transformations and their resolution
within the framework of geometrical superfield approach to BRST formalism. One
of the highlights of our results is the emergence of a Curci-Ferrari type of
restriction in the context of 4D Abelian 2-form (notoph) gauge theory which
renders the nilpotent (anti-) BRST symmetries of the theory to be absolutely
anticommutative in nature.Comment: LaTeX file, 12 pages, Talk delivered at SQS'09 (BLTP, JINR, Dubna
Performance of the ocean state forecast system at Indian National Centre for Ocean Information Services
The reliability of the operational Ocean State Forecast system at the Indian National Centre for Ocean Information Services (INCOIS) during tropical cyclones that affect the coastline of India is described in this article. The performance of this system during cyclone Thane that severely affected the southeast coast of India during the last week of December 2011 is reported here. Spec-tral wave model is used for forecasting the wave fields generated by the tropical cyclone and vali-dation of the same is done using real-time automated observation systems. The validation results indicate that the forecasted wave parameters agree well with the measurements. The feedback from the user community indicates that the forecast was reliable and highly useful. Alerts based on this operational ocean state forecast system are thus useful for protecting the property and lives of the coastal communities along the coastline of India. INCOIS is extending this service for the benefit of the other countries along the Indian Ocean rim
Wave forecasting and monitoring during very severe cyclone Phailin in the Bay of Bengal
Wave fields, both measured and forecast during the very severe cyclone Phailin, are discussed in this communication. Waves having maximum height of 13.54 m were recorded at Gopalpur, the landfall point of the cyclone. The forecast and observed significant wave heights matched well at Gopalpur with correlation coefficient of 0.98, RMS error of 0.35 m and scatter index of 14%. Forecasts were also validated in the open ocean and found to be reliable (scatter index < 15%). The study also revealed the presence of Southern Ocean swells with a peak period of 20-22 sec hitting Gopalpur coast along with the cyclone-generated waves
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