3,813 research outputs found
Biliary duodenostomy: a safe and easier biliary drainage procedure after choledochal cyst excision
Background/purpose: The treatment of choice for choledochal cyst (CC) is complete excision followed by biliary–enteric anastomosis. Roux-en-Y biliary jejunostomy has been favored by most surgeons for decades, with satisfying results. The use of biliary duodenostomy (BD) is another simple alternative for biliary drainage after CC excision. Our intermediate-term outcomes of both biliary drainage procedures after CC excision are presented.Methods: We carried out a retrospective analysis of the outcome of CC management in children operated at the Pediatric Surgery Department of Ain-Shams University over 5 years, from January 2010.Results: A total of 23 cases (16 females) were included in this study. The mean age at operation was 4.02 ± 2.52 years. Twenty-one cases had type I and two cases had type III CC. Complete excision of the CC was performed in 22 cases, and partial excision with mucosectomy was performed in one case. Biliary–enteric anastomosis was performed with the duodenum in 18 patients (group I, BD) and with the jejunum in five cases (group II, Roux-en-Y biliary jejunostomy). The mean follow-up period was 53± 4.48 months. A patient from group II suffered from ascending cholangitis 6 months postoperatively.Conclusion: BD is a simple technique for biliary drainage after CC excision with no major complications at intermediate-term follow-up.Keywords: biliary obstruction, choledochal cyst, hepaticoduodenostomy, jaundic
Born-Infeld-Einstein Actions?
We present some obvious physical requirements on gravitational avatars of
non-linear electrodynamics and illustrate them with explicit determinantal
Born-Infeld-Einstein models. A related procedure, using compensating Weyl
scalars, permits us to formulate conformally invariant versions of these
systems as well.Comment: 7 page
The prevalence of hepatitis B surface antigen and anti-hepatitis B core antibody in Iran: A population-based study
Background: Hepatitis B virus infection is a very common cause of chronic liver disease worldwide. It is estimated that 3 of Iranians are chronically infected with hepatitis B virus. Current population-based studies on both rural and urban prevalence of hepatitis B virus infection in Iran are sparse with results that do not always agree. We performed this study to find the prevalence of hepatitis B surface antigen, anti-hepatitis B core antibody, and associated factors in the general population of three provinces of Iran. Methods: We randomly selected 6,583 subjects from three provinces in Iran, namely Tehran, Golestan, and Hormozgan. The subjects were aged between 18 and 65 years. Serum samples were tested for hepatitis B surface antigen and anti-hepatitis B core antibody. Various risk factors were recorded and multivariate analysis was performed. Results: The prevalence of hepatitis B surface antigen and anti-hepatitis B core antibody in Iran was 2.6 and 16.4, respectively. Predictors of hepatitis B surface antigen or anti-hepatitis B core antibody in multivariate analysis included older age, not having high-school diploma, living in a rural area, and liver disease in a family member. We did not find any significant differences between males and females. Conclusion: In spite of nationwide vaccination of newborns against hepatitis B virus since 1992, hepatitis B virus infection remains a very common cause of chronic liver disease in Iran which should be dealt with for at least the next 30-50 years
New Polymer Syntheses Part: 55#. Novel Conducting Arylidene Polymers and Copolymers Based on Methyl-Cyclohexanone Moiety
A new interesting class of conducting polymers based on methyl-cyclohexanone in the polymer main chain has been synthesized by solution polycondensation of terephthalaldehyde with methyl-cyclohexanone. Copolymers containing different cycloalkanone moieties were also synthesized using solution polycondensation technique. The model compound I was synthesized by the interaction of methyl-cyclohexanone monomer with benzaldehyde, and its structure was confirmed by elemental and spectral analyses. The resulting new polymers and copolymers were characterized by elemental and spectral analyses, beside solubility and viscometry measurements. The thermal properties of those polymer and copolymers were evaluated by TGA, DrTGA and DTA measurements and correlated to their structural units. PDT as well as T10 was in the range from 205 to 370 ºC. In addition, T10 thermal stability for all the polymers was in theorder: VI> II > III > IV > V. X–ray analysis showed that it has some degree of crystallinity in the region 2q = 5–60 degree.The UV– visible spectra of some selected polymers were measured in DMSO solution and showed absorption bands in the range 265-397 nm, due to n – π* and π – π* transition. The morphological properties of copolymer IV as selected examples were tested by SEM. The electrical conductivities of the synthesized polymers and copolymers enhanced to become in the range of 10-9-10-8 S cm-1 by doping with iodine
Dynamics of BPS States in the Dirac-Born-Infeld Theory
The Dirac-Born-Infeld action with transverse scalar fields is considered to
study the dynamics of various BPS states. We first describe the characteristic
properties of the so-called 1/2 and 1/4 BPS states on the D3 brane, which can
be interpreted as F/D-strings ending on a D3-brane in Type IIB string theory
picture. We then study the response of the BPS states to low energy excitations
of massless fields on the brane, the scalar fields representing the shape
fluctuation of the brane and U(1) gauge fields describing the open string
excitations on the D-brane. This leads to an identification of interactions
between BPS states including the static potentials and the kinetic
interactions.Comment: 19 pages, 4 figures References added, Typographical errors are
correcte
Making the hyper--K\"ahler structure of N=2 quantum string manifest
We show that the Lorentz covariant formulation of N=2 string in a curved
space reveals an explicit hyper--K\"ahler structure. Apart from the metric, the
superconformal currents couple to a background two--form. By superconformal
symmetry the latter is constrained to be holomorphic and covariantly constant
and allows one to construct three complex structures obeying a
(pseudo)quaternion algebra.Comment: 8 pages, no figures, PACS: 04.60.Ds; 11.30.Pb, Keywords: N=2 string,
hyper-K\"ahler geometry. Presentation improved, references added. The version
to appear in PR
Design, synthesis, molecular modeling and biological evaluation of novel diaryl heterocyclic analogs as potential selective cyclooxygenase-2 (COX-2) inhibitors
AbstractNew series of 3,4-diaryl-2-thioxoimidazolidin-4-ones and 3-alkylthio-4,5-diaryl-4H-1,2,4-triazoles were designed, synthesized and evaluated for their activity as anti-inflammatory agents. Compounds 20, 21, 23 and 34 are highly selective inhibitors of COX-2 enzyme at a concentration of 100mM relative to celecoxib, the standard reference. (±)-3-(4-Phenoxy-phenyl)-5-phenyl-2-thioxoimidazolidin-4-ones 23 exhibited the most active anti-inflammatory agent
D-brane orbiting NS5-branes
We study real time dynamics of a Dp-brane orbiting a stack of NS5-branes. It
is generally known that a BPS D-brane moving in the vicinity of NS5-branes
becomes unstable due to the presence of tachyonic degree of freedom induced on
the D-brane. Indeed, the D-brane necessarily falls into the fivebranes due to
gravitational attraction and eventually collapses into a pressureless fluid.
Such a decay of the D-brane is known to be closely related to the rolling
tachyon problem. In this paper we show that in special cases the decay of
D-brane caused by gravitational attraction can be avoided. Namely for certain
values of energy and angular momentum the D-brane orbits around the fivebranes,
maintaining certain distance from the fivebranes all the time, and the process
of tachyon condensation is suppressed. We show that the tachyonic degree of
freedom induced on such a D-brane really disappears and the brane returns to a
stable D-brane.Comment: 12 pages, latex, added referenc
Chern-Simons Vortices in Supergravity
We study supersymmetric vortex solutions in three-dimensional abelian gauged
supergravity. First, we construct the general U(1)-gauged D=3, N=2 supergravity
whose scalar sector is an arbitrary Kahler manifold with U(1) isometry. This
construction clarifies the connection between local supersymmetry and the
specific forms of some scalar potentials previously found in the literature --
in particular, it provides the locally supersymmetric embedding of the abelian
Chern-Simons Higgs model. We show that the Killing spinor equations admit
rotationally symmetric vortex solutions with asymptotically conical geometry
which preserve half of the supersymmetry.Comment: 26 pages, LaTeX2
The geometry of N=4 twisted string
We compare N=2 string and N=4 topological string within the framework of the
sigma model approach. Being classically equivalent on a flat background, the
theories are shown to lead to different geometries when put in a curved space.
In contrast to the well studied Kaehler geometry characterising the former
case, in the latter case a manifold has to admit a covariantly constant
holomorphic two-form in order to support an N=4 twisted supersymmetry. This
restricts the holonomy group to be a subgroup of SU(1,1) and leads to a
Ricci--flat manifold. We speculate that, the N=4 topological formalism is an
appropriate framework to smooth down ultraviolet divergences intrinsic to the
N=2 theory.Comment: 20 pages, LaTe
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