694 research outputs found
BPS D-branes from an Unstable D-brane in a Curved Background
We find exact tachyon kink solutions of DBI type effective action describing
an unstable D5-brane with worldvolume gauge field turned on in a curved
background. The background of interest is the ten-dimensional lift of the
Salam-Sezgin vacuum and, in the asymptotic limit, it approaches . The solutions are identified as
composites of lower-dimensional D-branes and fundamental strings, and, in the
BPS limit, they become a D4D2F1 composite wrapped on where is inside . In one class of solutions we
find an infinite degeneracy with respect to a constant magnetic field along the
direction of NS-NS field on .Comment: 16 pages, 2 figures, a footnote added, typos corrected and a
reference adde
BPS D-branes from an Unstable D-brane
We search for exact tachyon kink solutions of DBI type effective action
describing an unstable D-brane with worldvolume gauge field turned in both the
flat and a curved background. There are various kinds of solutions in the
presence of electromagnetic fields in the flat space, such as periodic arrays,
topological tachyon kinks, half kinks, and bounces. We identify a BPS object,
D(-1)F1 bound state, which describes a thick brane with string flux density.
The curved background of interest is the ten-dimensional lift of the
Salam-Sezgin vacuum and, in the asymptotic limit, it approaches . The solutions in the curved
background are identified as composites of lower-dimensional D-branes and
fundamental strings, and, in the BPS limit, they become a D4D2F1 composite
wrapped on where is inside .Comment: 4 pages, to appear in the proceeding of PASCOS 2005, Gyeongju, Korea,
May 30-June 4, 200
Evolution of the Industrial Wage Structure in China Since 1980
Industry mean wages in China have exhibited sharply increased dispersion since the early 1990s. The upward trend in differences of average wages among major industry groups parallels increases in wage and income inequality not only between rural and urban sectors but within the urban economy as well. Research on the trend has focused on (1) how market forces have led to a better match between worker pay and worker skills; on (2a) how the growing share of employment in the private sector has “caused” growing wage inequality; and (2b) how residual government control in a few industrial sectors has contributed to wage inequality due monopoly rent sharing. We show that the industrial wage dispersion in China has evolved to match long-recognized international patterns of industrial wage dispersion and that an increasing proportion of industrial wage dispersion can be explained as returns to observed worker characteristics.inequality, China, industry-wage structure
Spectrum of Eleven-dimensional Supergravity on a PP-wave Background
We calculate the spectrum of the linearized supergravity around the maximally
supersymmetric pp-wave background in eleven dimensions. The resulting spectrum
agrees with that of zero-mode Hamiltonian of a supermembrane theory on the
pp-wave background. We also discuss the connection with the Kaluza-Klein zero
modes of AdS_4 x S^7 background.Comment: 17 pages, no figures, LaTeX2e, typos correcte
On Classical Equivalence Between Noncritical and Einstein Gravity : The AdS/CFT Perspectives
We find that noncritical gravity, a special class of higher derivative
gravity, is classically equivalent to Einstein gravity at the full nonlinear
level. We obtain the viscosity-to-entropy ratio and the second order transport
coefficients of the dual fluid of noncritical gravity to all orders in the
coupling of higher derivative terms. We also compute the holographic
entanglement entropy in the dual CFT of noncritical gravity. All these results
confirm the nonlinear equivalence between noncritical gravity and Einstein
gravity at the classical level.Comment: 19 pages, no figure
The effect of the DLTIDDSYWYRI motif of the human laminin α2 chain on implant osseointegration
Considerable effort has been directed towards replacing lost teeth using tissue-engineering methods such as titanium implants. A number of studies have tried to modify bioinert titanium surfaces by coating them with functionally bioactive molecules for faster and stronger osseointegration than pure titanium surfaces. Recently, peptides have been recognized as valuable scientific tools in the field of tissue-engineering. The DLTIDDSYWYRI motif of the human laminin-2 α2 chain has been previously reported to promote the attachment of various cell types; however, the in vivo effects of the DLTIDDSYWYRI motif on new bone formation have not yet been studied. To examine whether a laminin-2-derived peptide can promote osseointegration by accelerating new bone formation in vivo, we applied titanium implants coated with the DLTIDDSYWYRI motif in a rabbit tibia model. The application of the DLTIDDSYWYRI motif-treated implant to tibia wounds enhanced collagen deposition and alkaline phosphatase expression. It significantly promoted implant osseointegration compared with treatment with scrambled peptide-treated implants by increasing the bone-to-implant contact ratio and bone area. These findings support the hypothesis that the DLTIDDSYWYRI motif acts as an effective osseointegration accelerator by enhancing new bone formation.Considerable effort has been directed towards replacing lost teeth using tissue-engineering methods such as titanium implants. A number of studies have tried to modify bioinert titanium surfaces by coating them with functionally bioactive molecules for faster and stronger osseointegration than pure titanium surfaces. Recently, peptides have been recognized as valuable scientific tools in the field of tissue-engineering. The DLTIDDSYWYRI motif of the human laminin-2 α2 chain has been previously reported to promote the attachment of various cell types; however, the in vivo effects of the DLTIDDSYWYRI motif on new bone formation have not yet been studied. To examine whether a laminin-2-derived peptide can promote osseointegration by accelerating new bone formation in vivo, we applied titanium implants coated with the DLTIDDSYWYRI motif in a rabbit tibia model. The application of the DLTIDDSYWYRI motif-treated implant to tibia wounds enhanced collagen deposition and alkaline phosphatase expression. It significantly promoted implant osseointegration compared with treatment with scrambled peptide-treated implants by increasing the bone-to-implant contact ratio and bone area. These findings support the hypothesis that the DLTIDDSYWYRI motif acts as an effective osseointegration accelerator by enhancing new bone formation.Tissue-engineeringThis work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by MEST (Grant No. 2011-0007662) and the Mid-career Researcher Program through NRF, funded by MEST (Grant No. 2010-0014662).OAIID:oai:osos.snu.ac.kr:snu2013-01/102/2008003883/1SEQ:1PERF_CD:SNU2013-01EVAL_ITEM_CD:102USER_ID:2008003883ADJUST_YN:NEMP_ID:A078517DEPT_CD:861CITE_RATE:7.404FILENAME:Biomaterials 201305 34(16) 4027-37.pdfDEPT_NM:치의학과EMAIL:[email protected]_YN:YCONFIRM:
AdS/BCFT Correspondence for Higher Curvature Gravity: An Example
We consider the effects of higher curvature terms on a holographic dual
description of boundary conformal field theory. Specifically, we consider
three-dimensional gravity with a specific combination of Ricci tensor square
and curvature scalar square, so called, new massive gravity. We show that a
boundary entropy and an entanglement entropy are given by similar expression
with those of the Einstein gravity case when we introduce an {\it effective}
Newton's constant and an {\it effective} cosmological constant. We also show
that the holographic g-theorem still holds in this extension, and we give some
comments about the central charge dependence of boundary entropy in the
holographic construction. In the same way, we consider new type black holes and
comment on the boundary profile. Moreover, we reproduce these results through
auxiliary field formalism in this specific higher curvature gravity.Comment: 27pages, minor corrections, accepted in JHE
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