335 research outputs found
Renal Vein Thrombosis
ObjectiveThe aim of this article is to review the published English literature on aetiology, pathology, clinical presentation, diagnostic methods and treatment of renal vein thrombosis.Materials and methodsWe searched the published literature from Medline & Pubmed using keywords renal vein thrombosis, anti-phospholipid syndrome and nephrotic syndrome. Data was extracted from individual case reports, case series, articles on pathology, diagnostic tests, treatment modalities, and previous reviews. Case reports which did not add any new information were excluded.ResultsWe selected 60 references based on the above criteria. Renal vein thrombosis is relatively rare. CT angiography is considered the investigation of choice. Alternatives include MR angiography or renal venography in highly selected patients. As the condition is relatively uncommon, consensus on the best form of therapy for this condition has been slow to evolve. The trend in management has shifted to non-surgical therapies particularly systemic anticoagulation except in highly selected group of patients
Geometric Transition versus Cascading Solution
We study Vafa's geometric transition and Klebanov - Strassler solution from
various points of view in M-theory. In terms of brane configurations, we show
the detailed equivalences between the two models. In some limits, both models
have an alternative realization as fourfolds in M-theory with appropriate
G-fluxes turned on. We discuss some aspects of the fourfolds including how to
see the transition and a possible extension to the non-supersymmetric case.Comment: 34 pages, LaTex, 2 figures; v2: Some comments added and references
updated. Final version to appear in JHE
No Go Theorem for Self Tuning Solutions With Gauss-Bonnet Terms
We consider self tuning solutions for a brane embedded in an anti de Sitter
spacetime. We include the higher derivative Gauss-Bonnet terms in the action
and study singularity free solutions with finite effective Newton's constant.
Using the methods of Csaki et al, we prove that such solutions, when exist,
always require a fine tuning among the brane parameters. We then present a new
method of analysis in which the qualitative features of the solutions can be
seen easily without obtaining the solutions explicitly. Also, the origin of the
fine tuning is transparent in this method.Comment: 17 pages, 3 figure
Cascading RG Flows from New Sasaki-Einstein Manifolds
In important recent developments, new Sasaki-Einstein spaces and
conformal gauge theories dual to have been constructed.
We consider a stack of N D3-branes and M wrapped D5-branes at the apex of a
cone over . Replacing the D-branes by their fluxes, we construct
asymptotic solutions for all p and q in the form of warped products of the cone
and . We show that they describe cascading RG flows where N decreases
logarithmically with the scale. The warp factor, which we determine explicitly,
is a function of the radius of the cone and one of the coordinates on
. We describe the RG cascades in the dual quiver gauge theories, and
find an exact agreement between the supergravity and the field theory beta
functions. We also discuss certain dibaryon operators and their dual wrapped
D3-branes in the conformal case M=0.Comment: 22 pages, 6 figures; v2 minor corrections; v3 refs, orbifold
discussion added; v4 more ref
Percolation in deposits for competitive models in (1+1)-dimensions
The percolation behaviour during the deposit formation, when the spanning
cluster was formed in the substrate plane, was studied. Two competitive or
mixed models of surface layer formation were considered in (1+1)-dimensional
geometry. These models are based on the combination of ballistic deposition
(BD) and random deposition (RD) models or BD and Family deposition (FD) models.
Numerically we find, that for pure RD, FD or BD models the mean height of the
percolation deposit grows with the substrate length according to
the generalized logarithmic law , where
(RD), (FD) and (BD).
For BD model, the scaling law between deposit density and its mean height
at the point of percolation of type are observed, where is a scaling
coefficient. For competitive models the crossover, %in versus
corresponding to the RD or FD -like behaviour at small and the BD-like
behaviour at large are observed.Comment: 8 pages,4 figures, Latex, uses iopart.cl
Supersymmetric probes on the conifold
We study the supersymmetric embeddings of different D-brane probes in the
AdS_5 x T^{1,1} geometry. The main tool employed is kappa symmetry and the
cases studied include D3-, D5- and D7-branes. We find a family of three-cycles
of the T^{1,1} space over which a D3-brane can be wrapped supersymmetrically
and we determine the field content of the corresponding gauge theory duals.
Supersymmetric configurations of D5-branes wrapping a two-cycle and of
spacetime filling D7-branes are also found. The configurations in which the
entire T^{1,1} space is wrapped by a D5-brane (baryon vertex) and a D7-brane
are also studied. Some other embeddings which break supersymmetry but are
nevertheless stable are also determined.Comment: 44 pages, LaTeX; v2: typos corrected, references added, discussion of
D5-brane embeddings improve
Supersymmetric IIB Solutions with Schr\"{o}dinger Symmetry
We find a class of non-relativistic supersymmetric solutions of IIB
supergravity with non-trivial B-field that have dynamical exponent n=2 and are
invariant under the Schrodinger group. For a general Sasaki-Einstein internal
manifold with U(1)^3 isometry, the solutions have two real supercharges. When
the internal manifold is S^5, the number of supercharges can be four. We also
find a large class of non-relativistic scale invariant type IIB solutions with
dynamical exponents different from two. The explicit solutions and the values
of the dynamical exponents are determined by vector eigenfunctions and
eigenvalues of the Laplacian on an Einstein manifold.Comment: 28 pages, LaTe
An Index for 4 dimensional Super Conformal Theories
We present a trace formula for an index over the spectrum of four dimensional
superconformal field theories on time. Our index receives
contributions from states invariant under at least one supercharge and captures
all information -- that may be obtained purely from group theory -- about
protected short representations in 4 dimensional superconformal field theories.
In the case of the theory our index is a function of four
continuous variables. We compute it at weak coupling using gauge theory and at
strong coupling by summing over the spectrum of free massless particles in
and find perfect agreement at large and small charges.
Our index does not reproduce the entropy of supersymmetric black holes in
, but this is not a contradiction, as it differs qualitatively from the
partition function over supersymmetric states of the theory. We
note that entropy for some small supersymmetric black holes may be
reproduced via a D-brane counting involving giant gravitons. For big black
holes we find a qualitative (but not exact) agreement with the naive counting
of BPS states in the free Yang Mills theory. In this paper we also evaluate and
study the partition function over the chiral ring in the Yang
Mills theory.Comment: harvmac 40+16 pages, v3: references and table of contents added,
typos fixe
Half-BPS cosmic string in N=2 supergravity in the presence of a dilaton
We construct new half-BPS cosmic string solutions in D=4 N=2 supergravity
compatible with a consistent truncation to N=1 supergravity where they describe
D-term cosmic strings. The constant Fayet-Iliopoulos term in the N=1 D-term is
not put in by hand but is geometrically engineered by a gauging in the mother
N=2 supergravity theory. The coupling of the N=2 vector multiplets is
characterized by a cubic prepotential admitting an axion-dilaton field, a
common property of many compactifications of string theory. The axion-dilaton
field survives the truncation to N=1 supergravity. On the string configuration
the BPS equations constrain the dilaton to be an arbitrary constant. All the
cosmic string solutions with different values of the dilaton have the same
energy per unit length but different lenght scales.Comment: 52 pages; typos correcte
Hierarchies from Fluxes in String Compactifications
Warped compactifications with significant warping provide one of the few
known mechanisms for naturally generating large hierarchies of physical scales.
We demonstrate that this mechanism is realizable in string theory, and give
examples involving orientifold compactifications of IIB string theory and
F-theory compactifications on Calabi-Yau four-folds. In each case, the
hierarchy of scales is fixed by a choice of RR and NS fluxes in the compact
manifold. Our solutions involve compactifications of the Klebanov-Strassler
gravity dual to a confining N=1 supersymmetric gauge theory,and the hierarchy
reflects the small scale of chiral symmetry breaking in the dual gauge theory.Comment: 35 pages. v2: minor eqn. and reference change
- âŠ