Cosmological constant and gravitational theory on D-brane

In a toy model we derive the gravitational equation on a self-gravitating curved D-brane. The effective theory on the brane is drastically changed from the ordinal Einstein equation. The net cosmological constant on the brane depends on a tuning between the brane tension and the brane charges. Moreover, non-zero matter stress tensor exists if the net cosmological constant is not zero. This fact indicates a direct connection between matters on the brane and the dark energy.Comment: 6 pages, minor corrections, accepted for publication in Physical Review

Low energy effective action on a self-gravitating D-brane

Recently the study of braneworld on the self-gravitating D-brane has been initiated and derived the gravitational equation on the brane by holographic and geometrical projection methods. Surprisingly, in common with these two methods, the matter on the brane cannot be the source of the gravity on the brane at leading order. In this paper we will propose the low energy effective action on the D-brane coupled with gravity which derives the same results.Comment: 8 pages, minor corrections, accepted for publication in Physical Review

Can we live on a D-brane? -- Effective theory on a self-gravitating D-brane --

We consider a D-brane coupled with gravity in type IIB supergravity on S^5 and derive the effective theory on the D-brane in two different ways, that is, holographic and geometrical projection methods. We find that the effective equations on the brane obtained by these methods coincide. The theory on the D-brane described by the Born-Infeld action is not like Einstein-Maxwell theory in the lower order of the gradient expansion, i.e., the Maxwell field does not appear in the theory. Thus the careful analysis and statement for cosmology on self-gravitating D-brane should be demanded in realistic models.Comment: 13 pages, accepted for publication in Physical Review

膵癌術後予防肝動注におけるリザーバー留置術の検討 : 従来法とcoaxialシステムの比較

PURPOSE: Previous reports have shown the effectiveness of adjuvant hepatic arterial infusion chemotherapy (HAIC) in pancreatic cancer. However, percutaneous catheter placement is technically difficult after pancreatic surgery. The purpose of this study was to evaluate the feasibility and outcome of HAIC using a coaxial technique compared with conventional technique for postoperative pancreatic cancer. MATERIALS AND METHODS: 93 consecutive patients who received percutaneous catheter-port system placement after pancreatectomy were enrolled. In 58 patients from March 2006 to August 2010 (Group A), a conventional technique with a 5-Fr indwelling catheter was used and in 35 patients from September 2010 to September 2012 (Group B), a coaxial technique with a 2.7-Fr coaxial catheter was used. RESULTS: The overall technical success rates were 97.1 % in Group B and 86.2 % in Group A. In cases with arterial tortuousness and stenosis, the success rate was significantly higher in Group B (91.7 vs. 53.8 %; P = 0.046). Fluoroscopic and total procedure times were significantly shorter in Group B: 14.7 versus 26.7 min (P = 0.001) and 64.8 versus 80.7 min (P = 0.0051), respectively. No differences were seen in the complication rate. The 1 year liver metastasis rates were 9.9 % using the conventional system and 9.1 % using the coaxial system (P = 0.678). The overall median survival time was 44 months. There was no difference in the survival period between two systems (P = 0.312). CONCLUSIONS: The coaxial technique is useful for catheter placement after pancreatectomy, achieving a high success rate and reducing fluoroscopic and procedure times, while maintaining the safety and efficacy for adjuvant HAIC in pancreatic cancer.博士（医学）・乙第1380号・平成28年7月8日© Springer Science+Business Media New York and the Cardiovascular and Interventional Radiological Society of Europe (CIRSE) 2016The final publication is available at Springer via http://dx.doi.org/10.1007/s00270-016-1292-

Effective theory for close limit of two branes

We discuss the effective theory for the close limit of two branes in a covariant way. To do so we solve the five dimensional Einstein equation along the direction of the extra dimension. Using the Taylor expansion we solve the bulk spacetimes and derive the effective theory describing the close limit. We also discuss the radion dynamics and braneworld black holes for the close limit in our formulation.Comment: 6 pages, a version to be published in Phy.Rev.

D-braneworld cosmology

We discuss D-braneworld cosmology, that is, the brane is described by the Born-Infeld action. Compared with the usual Randall-Sundrum braneworld cosmology where the brane action is the Nambu-Goto one, we can see some drastic changes at the very early universe: (i)universe may experience the rapid accelerating phase (ii)the closed universe may avoid the initial singularity. We also briefly address the dynamics of the cosmology in the open string metric, which might be favorer than the induced metric from the view point of the D-brane.Comment: 6 pages, 3 figures, minor corrections, accepted for publication in Phys. Rev.

Low energy effective theory on a regularized brane in 6D gauged chiral supergravity

We derive the low energy effective theory on a brane in six-dimensional chiral supergravity. The conical 3-brane singularities are resolved by introducing cylindrical codimension one 4-branes whose interiors are capped by a regular spacetime. The effective theory is described by the Brans-Dicke (BD) theory with the BD parameter given by $\omega_{\rm BD}=1/2$. The BD field is originated from a modulus which is associated with the scaling symmetry of the system. If the dilaton potentials on the branes preserve the scaling symmetry, the scalar field has an exponential potential in the Einstein frame. We show that the time dependent solutions driven by the modulus in the four-dimensional effective theory can be lifted up to the six-dimensional exact solutions found in the literature. Based on the effective theory, we discuss a possible way to stabilize the modulus to recover standard cosmology and also study the implication for the cosmological constant problem.Comment: 12 pages, 1 figur

Curated genome annotation of Oryza sativa ssp. japonica and comparative genome analysis with Arabidopsis thaliana

We present here the annotation of the complete genome of rice Oryza sativa L. ssp. japonica cultivar Nipponbare. All functional annotations for proteins and non-protein-coding RNA (npRNA) candidates were manually curated. Functions were identified or inferred in 19,969 (70%) of the proteins, and 131 possible npRNAs (including 58 antisense transcripts) were found. Almost 5000 annotated protein-coding genes were found to be disrupted in insertional mutant lines, which will accelerate future experimental validation of the annotations. The rice loci were determined by using cDNA sequences obtained from rice and other representative cereals. Our conservative estimate based on these loci and an extrapolation suggested that the gene number of rice is ~32,000, which is smaller than previous estimates. We conducted comparative analyses between rice and Arabidopsis thaliana and found that both genomes possessed several lineage-specific genes, which might account for the observed differences between these species, while they had similar sets of predicted functional domains among the protein sequences. A system to control translational efficiency seems to be conserved across large evolutionary distances. Moreover, the evolutionary process of protein-coding genes was examined. Our results suggest that natural selection may have played a role for duplicated genes in both species, so that duplication was suppressed or favored in a manner that depended on the function of a gene