Accelerating Cosmologies from S-Branes

We point out that the recently proposed model of a flat 4-dimensional universe with accelerated expansion in string/M-theory is a special case of time-dependent solutions that the author found under the name of ``S-branes.'' We also show that similar accelerating models can be obtained from S-branes if the internal space is chosen to be hyperbolic or flat spaces.Comment: 8 pages, 4 figures, comments added, a typo corrected, final version to appear in Phys. Rev. Let

AdS/CFT Correspondence with a 3D Black Hole Simulator

The AdS/CFT correspondence has been insightful for high-energy and condensed matter physics alike. An application of this correspondence is the duality between the entanglement entropy of Anti-de Sitter (AdS) black holes and lower-dimensional conformal field theories (CFT). To explicitly demonstrate this correspondence we simulate the effect a 3D black hole geometry has on Dirac fields by employing a square lattice of fermions with inhomogeneous tunnelling couplings. Simulating a 3D BTZ black hole horizon, we numerically obtain an area law behaviour that is in agreement with the corresponding 2D CFT with a central charge that depends on the cosmological constant of the AdS space. A systematic numerical investigation of various 3D black hole profiles suggests that all 3D black holes give an entropic behaviour that can be represented by the same CFT.Comment: 6 pages, 4 figure

AdS/CFT correspondence with a three-dimensional black hole simulator

One of the key applications of AdS/CFT correspondence is the duality it dictates between the entanglement entropy of anti–de Sitter (AdS) black holes and lower-dimensional conformal field theories (CFTs). Here we employ a square lattice of fermions with inhomogeneous tunneling couplings that simulate the effect rotationally symmetric three-dimensional (3D) black holes have on Dirac fields. When applied to 3D Banados-Teitelboim-Zanelli (BTZ) black holes we identify the parametric regime where the theoretically predicted two-dimensional CFT faithfully describes the black hole entanglement entropy. With the help of the universal simulator, we further demonstrate that a large family of 3D black holes exhibit the same ground-state entanglement entropy behavior as the BTZ black hole. The simplicity of our simulator enables direct numerical investigation of a wide variety of 3D black holes and the possibility to experimentally realize it with optical lattice technology

Non-Standard Intersections of S-Branes in D=11 Supergravity

We construct new intersecting S-brane solutions in 11-dimensional supergravity which do not have supersymmetric analogs. They are obtained by letting brane charges to be proportional to each other. Solutions fall into two categories with respect to whether there is a non-diagonal term to be cancelled in the field equations or not. In each case we show that they can be constructed by using a simple set of rules which is similar to the harmonic function rule of the usual static p-branes. Furthermore, we study an intersection where the Chern-Simons term makes a non-zero contribution to the field equations. We show that this configuration has a singularity like other S-branes.Comment: 13 pages, 2 figures;v2 Section 2.2 is improved with new examples, references added;v3 typos correcte

Cytotoxic Effect of Turkish Propolis on Liver, Colon, Breast, Cervix and Prostate Cancer Cell Lines

Purpose: To investigate the total polyphenolic and flavonoid contents, antioxidant power and cytotoxic activity of ethanol extracts of Turkish propolis (EEP).Methods: The total polyphenolic and flavonoid contents of EEP were determined by spectrometric methods. Antioxidant power and cytotoxic activity of EEP were evaluated using ferric reducing antioxidant power (FRAP) and MTT assays, respectively.Results: The total polyphenolic and flavonoid contents, and FRAP value of EEP were 124.6 ± 1.5 mg gallic acid/g sample dry weight , 42.0 ± 0.8 mg quercetin/g sample dry weight and 311.0 ± 2.5 mg trolox/g sample dry weight, respectively. EEP exhibited powerful cytotoxic effects against the five human cancer cell lines. The highest cytotoxic activity of Turkish EEP was demonstrated on PC-3 cell line (IC50 = 20.7±3.4 μg/mL).Conclusion: The results demonstrate that EEP is a good source of antioxidant and a natural antitumor agent capable  of reducing cancer cell proliferation.Keywords: Propolis, Polyphenols, Cytotoxic effect, Cancer cell lines, Antioxidant activity Tropical Journal of  Pharmaceutical Research is indexed by Science Citation Index (SciSearch)

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

S-brane Actions

We derive effective actions for Spacelike branes (S-branes) and find a solution describing the formation of fundamental strings in the rolling tachyon background. The S-brane action is a Dirac-Born-Infeld action for Euclidean worldvolumes defined in the context of time-dependent tachyon condensation of non-BPS branes. It includes gauge fields and in particular a scalar field associated with translation along the time direction. We show that the BIon spike solutions constructed in this system correspond to the production of a confined electric flux tube (a fundamental string) at late time of the rolling tachyon.Comment: 10 pages, 1 figure. References added, typos correcte

De novo Renal Transplantation after Kaposi Sarcoma: Favorable Outcome in a Patient Receiving Sirolimus and Mycophenolate-Based Immunosuppression

Immunosuppressive treatment increases the risk of infection and malignancy in organ transplant recipients. We report on a 42-year-old male renal transplant recipient who lost his first graft after reduction of immunosuppressive treatment due to Kaposi sarcoma and who successfully underwent a second renal transplant 10 years later. The patient's current treatment consists of low-dose prednisone, and the two antiproliferative immunosuppressants mycophenolate mofetil and rapamycin. 4.5 years after his second transplant, the serum creatinine is 1 mg/dl and the patient has no signs of recurrent disease

Calabi-Yau Fourfolds with Flux and Supersymmetry Breaking

In Calabi-Yau fourfold compactifications of M-theory with flux, we investigate the possibility of partial supersymmetry breaking in the three-dimensional effective theory. To this end, we place the effective theory in the framework of general N=2 gauged supergravities, in the special case where only translational symmetries are gauged. This allows us to extract supersymmetry-breaking conditions, and interpret them as conditions on the 4-form flux and Calabi-Yau geometry. For N=2 unbroken supersymmetry in three dimensions we recover previously known results, and we find a new condition for breaking supersymmetry from N=2 to N=1, i.e. from four to two supercharges. An example of a Calabi-Yau hypersurface in a toric variety that satisfies this condition is provided.Comment: 26 page