88,086 research outputs found
From the octagon to the SFT vertex - gluing and multiple wrapping
We compare various ways of decomposing and decompactifying the string field
theory vertex and analyze the relations between them. We formulate axioms for
the octagon and show how it can be glued to reproduce the decompactified
pp-wave SFT vertex which in turn can be glued to recover the exact finite
volume pp-wave Neumann coefficients. The gluing is performed by resumming
multiple wrapping corrections. We observe important nontrivial contributions at
the multiple wrapping level which are crucial for obtaining the exact results.Comment: 25 pages, many small figure
Branes wrapping black holes as a purely gravitational dielectric effect
In this paper we give a microscopical description of certain configurations
of branes wrapping black hole horizons in terms of dielectric gravitational
waves. Interestingly, the configurations are stable only due to the
gravitational background. Therefore, this constitutes a nice example of purely
gravitational dielectric effect.Comment: 17 pages, no figures. JHEP published versio
Understanding cellular internalization pathways of silicon nanowires
BACKGROUND: Understanding how cells interact with nanomaterials is important for rational design of nanomaterials for nanomedicine and transforming them for clinical applications. Particularly, the mechanism for one-dimensional (1D) nanomaterials with high aspect ratios still remains unclear. RESULTS: In this work, we present amine-functionalized silicon nanowires (SiNW-NH2) entering CHO-β cells via a physical membrane wrapping mechanism. By utilizing optical microscopy, transmission electron microscopy, and confocal fluorescence microscopy, we successfully visualized the key steps of internalization of SiNW-NH2 into cells. CONCLUSION: Our results provide insight into the interaction between 1D nanomaterials and confirm that these materials can be used for understanding membrane mechanics through physical stress exerted on the membrane
Brane Gas Cosmology, M-theory and Little String Theory
We generalize the Brane Gas Cosmological Scenario to M-theory degrees of
freedom, namely and branes. Without brane intersections, the
Brandenberger Vafa(BV) arguments applied to M-theory degrees of freedom
generically predict a large 6 dimensional spacetime. We show that intersections
of and branes can instead lead to a large 4 dimensional spacetime.
One dimensional intersections in 11D is related to (2,0) little strings (LST)
on NS5 branes in type IIA. The gas regime of membranes in M-theory corresponds
to the thermodynamics of LST obtained from holography. We propose a mechanism
whereby LST living on the worldvolume of NS5 (M5)-branes wrapping a five
dimensional torus, annihilate most efficiently in 3+1 dimensions leading to a
large 3+1 dimensional spacetime. We also show that this picture is consistent
with the gas approximation in M-theory.Comment: 8 page
AdS spacetimes from wrapped M5 branes
We derive a complete geometrical characterisation of a large class of
, and supersymmetric spacetimes in eleven-dimensional
supergravity using G-structures. These are obtained as special cases of a class
of supersymmetric , and
geometries, naturally associated to M5-branes wrapping calibrated cycles in
manifolds with , SU(3) or SU(2) holonomy. Specifically, the latter class
is defined by requiring that the Killing spinors satisfy the same set of
projection conditions as for wrapped probe branes, and that there is no
electric flux. We show how the R-symmetries of the dual field theories appear
as isometries of the general AdS geometries. We also show how known solutions
previously constructed in gauged supergravity satisfy our more general
G-structure conditions, demonstrate that our conditions for half-BPS
geometries are precisely those of Lin, Lunin and Maldacena, and construct some
new singular solutions.Comment: 1+56 pages, LaTeX; v2, references added; v3, minor corrections, final
version to appear in JHE
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