3,165 research outputs found
Descriptive study of outcome of antibiotic cement-impregnated intramedullary nail in treatment of infected non-union of weight bearing long bones
Background: Infected non-union of tibia and femur is a debilitating disorder for patient as well as challenging task for treating surgeon. Conventionally treatment of infected non-union is a two staged procedure. But antibiotic cement-impregnated intramedullary nailing (ACIINs) is a single staged and cost-effective procedure. Hence we intended to study the outcome of ACIIN use in infected non-union of tibia and femur.Methods: This is a hospital based prospective case series type of descriptive study conducted in Department of Orthopedics, SMS Medical College and Hospital, Jaipur. We studied 35 cases of infected non-union of femur and tibia fracture with interlock nail in situ. All patients were treated with interlock nail removal, debridement and freshening of sclerosed bony ends and fixation with ACIIN. All were followed for at least 6 months for infection control and bony union and final results were evaluated by Paley’s bony criteria and functional criteria.Results: Infection was controlled in 94.28% cases. Bony union was achieved in 88.57% cases (19 femur and 12 tibia). Average duration for bony union was 7.3 months for femur and 8 months for tibia. According to Paley’s criteria for bony outcome and functional outcome 65.71% and 51.43% had shown excellent outcome respectively.Conclusions: ACIIN is a good modality for treatment of infected non union of tibia and femur in terms of infection control and bony union and has a good functional outcome when bone gap is less
Flux Vacua Statistics for Two-Parameter Calabi-Yau's
We study the number of flux vacua for type IIB string theory on an
orientifold of the Calabi-Yau expressed as a hypersurface in WCP^4[1,1,2,2,6]
by evaluating a suitable integral over the complex-structure moduli space as
per the conjecture of Douglas and Ashok. We show that away from the singular
conifold locus, one gets a power law, and that the (neighborhood) of the
conifold locus indeed acts as an attractor in the (complex structure) moduli
space. We also study (non)supersymmetric solutions near the conifold locus.In
the process, we evaluate the periods near the conifold locus. We also study
(non)supersymmetric solutions near the conifold locus, and show that
supersymmetric solutions near the conifold locus do not support fluxes.Comment: 17 pages, LaTex; Part of AN's BTech
end-of-undergraduate-freshman(=first)-year summer project at IIT Roorkee; v3:
a reference and clarifying text and equations added, a numerical error
correcte
Reconstruction of hidden 3D shapes using diffuse reflections
We analyze multi-bounce propagation of light in an unknown hidden volume and
demonstrate that the reflected light contains sufficient information to recover
the 3D structure of the hidden scene. We formulate the forward and inverse
theory of secondary and tertiary scattering reflection using ideas from energy
front propagation and tomography. We show that using careful choice of
approximations, such as Fresnel approximation, greatly simplifies this problem
and the inversion can be achieved via a backpropagation process. We provide a
theoretical analysis of the invertibility, uniqueness and choices of
space-time-angle dimensions using synthetic examples. We show that a 2D streak
camera can be used to discover and reconstruct hidden geometry. Using a 1D high
speed time of flight camera, we show that our method can be used recover 3D
shapes of objects "around the corner"
Proper acceleration, geometric tachyon and dynamics of a fundamental string near D branes
We present a detailed analysis of our recent observation that the origin of
the geometric tachyon, which arises when a D-brane propagates in the
vicinity of a stack of coincident NS5-branes, is due to the proper acceleration
generated by the background dilaton field. We show that when a fundamental
string (F-string), described by the Nambu-Goto action, is moving in the
background of a stack of coincident D-branes, the geometric tachyon mode can
also appear since the overall conformal mode of the induced metric for the
string can act as a source for proper acceleration. We also studied the
detailed dynamics of the F-string as well as the instability by mapping the
Nambu-Goto action of the F-string to the tachyon effective action of the
non-BPS D-string. We qualitatively argue that the condensation of the geometric
tachyon is responsible for the (F,D) bound state formation.Comment: 26 pages, v2: added references, v3: one ref. updated, to appear in
Class. and Quant. Gravit
Duality and Integrability of Two Dimensional String Effective Action
We present a prescription for constructing the monodromy matrix, , for invariant string effective actions and derive its
transformation properties under the -duality group. This allows us to
construct for new backgrounds, starting from known ones,
which are related by -duality. As an application, we derive the monodromy
matrix for the exactly solvable Nappi-Witten model, both when B=0 and .Comment: 6pages, revtex, to be published in Physics Letters
Anti-de-Sitter Island-Universes from 5D Standing Waves
We construct simple standing wave solutions in a 5D space-time with a ghost
scalar field. The nodes of these standing waves are 'islands' of 4D Minkowski
space-time. For the 5D model with increasing (decreasing) warp factor there are
a finite (infinite) number of nodes and thus Minkowski island-universes having
different parameters, such as gravitational and cosmological constants. This
feature is similar to the assumptions of the landscape models, which postulate
a large number of universes with different parameters. This standing wave
solution also provides a new localization mechanism - matter fields can reside
only on Minkowski 'islands', where the background space-time does not
oscillate.Comment: 14 page pre-print format. Discussion about connection to Weyl gravity
added and "E&M" localization method added. To be published MPL
Tachyon Condensation on the Elliptic Curve
We use the framework of matrix factorizations to study topological B-type
D-branes on the cubic curve. Specifically, we elucidate how the brane RR
charges are encoded in the matrix factors, by analyzing their structure in
terms of sections of vector bundles in conjunction with equivariant R-symmetry.
One particular advantage of matrix factorizations is that explicit moduli
dependence is built in, thus giving us full control over the open-string moduli
space. It allows one to study phenomena like discontinuous jumps of the
cohomology over the moduli space, as well as formation of bound states at
threshold. One interesting aspect is that certain gauge symmetries inherent to
the matrix formulation lead to a non-trivial global structure of the moduli
space. We also investigate topological tachyon condensation, which enables us
to construct, in a systematic fashion, higher-dimensional matrix factorizations
out of smaller ones; this amounts to obtaining branes with higher RR charges as
composites of ones with minimal charges. As an application, we explicitly
construct all rank-two matrix factorizations.Comment: 69p, 6 figs, harvmac; v2: minor change
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