207 research outputs found
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
Anti-de Sitter no-hair, AdS/CFT and the brane-world
We study the asymptotic behavior of the bulk spacetimes with the negative
cosmological constant in the context of the brane-world scenario. We show that,
in Euclidean bulk, or in Lorentzian static bulk, some sequences of
hypersurfaces with the positive Ricci scalar evolve to the warped geometries
like the anti-de Sitter spacetime. Based on the AdS/CFT correspondence, we
discuss that the positivity of the Ricci scalar is related to the stability of
CFT on the brane. In addition, the brane-world is described from the
holographic point of view. The asymptotic local structure of the conformal
infinity is also investigated.Comment: 6 pages, minor changes, to appear in Phys. Rev.
Chemical Characterization of a Volatile Dubnium Compound, DbOCl3
The formation and the chemical characterization of single atoms of dubnium (Db, element 105), in the form of its volatile oxychloride, was investigated using the on-line gas phase chromatography technique, in the temperature range 350–600 °C. Under the exactly same chemical conditions, comparative studies with the lighter homologues of Group 5 in the Periodic Table clearly indicate the volatility sequence being NbOCl3 > TaOCl3 ≥ DbOCl3. From the obtained experimental results, thermochemical data for DbOCl3 were derived. The present study delivers reliable experimental information for theoretical calculations on chemical properties of transactinides
Predictions of and in an Asymptotically Non-Free Theory
We discuss an extention of the Minimal Supersymmetric Standard Model (MSSM)
with the 4th and anti-4th generations which have
invariant masses. Due to the the extra generations, all three running gauge
couplings become asymptotically non--free while preserving gauge coupling
unification at the GUT scale. We show that due to the asymptotically non--free
character of the gauge couplings: (1) the top and bottom Yukawa couplings are
strongly focused onto infrared fixed points as they are evolved down in scale
making their values at \mu=\mz insensitive to their initial values at
\mu=\mgut; (2) the model predicts \R(\mz) \equiv Y_b/Y_\tau |_{\mu
=\mz}\approx 1.8, which is consistent with the experimental value provided we
take the ratio of Yukawa couplings at the GUT scale to be \R(\mgut) =
Y_b/Y_\tau |_{\mu = \mgut} = 1/3; (3) the mass prediction comes out to be
\mt\approx 180\,\GeV which is also consistent with experiment.Comment: 20 pgs. 7 figures. Latex2e. othersym.sty, suceqn.sty include
Study of fission using multi-nucleon transfer reactions
Multi-nucleon transfer channels of the reactions of 18O+232Th, 18O+238U, 18O+248Cm were used to measure fission-fragment mass distribution for various nuclides and their excitation energy dependence. Predominantly asymmetric fission is observed at low excitation energies for all the studied cases, with an increase of the symmetric fission towards high excitation energies. Experimental data are compared with predictions of the fluctuation-dissipation model, where effects of multi-chance fission (neutron evaporation prior to fission) was introduced. It was shown that a reliable understanding of the observed fission fragment mass distributions can be obtained only invoking multi-chance fissions
CVIT expert consensus document on primary percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI) in 2018
While primary percutaneous coronary intervention (PCI) has significantly contributed to improve the mortality in patients with ST segment elevation myocardial infarction even in cardiogenic shock, primary PCI is a standard of care in most of Japanese institutions. Whereas there are high numbers of available facilities providing primary PCI in Japan, there are no clear guidelines focusing on procedural aspect of the standardized care. Whilst updated guidelines for the management of acute myocardial infarction were recently published by European Society of Cardiology, the following major changes are indicated; (1) radial access and drug-eluting stent over bare metal stent were recommended as Class I indication, and (2) complete revascularization before hospital discharge (either immediate or staged) is now considered as Class IIa recommendation. Although the primary PCI is consistently recommended in recent and previous guidelines, the device lag from Europe, the frequent usage of coronary imaging modalities in Japan, and the difference in available medical therapy or mechanical support may prevent direct application of European guidelines to Japanese population. The Task Force on Primary Percutaneous Coronary Intervention of the Japanese Association of Cardiovascular Intervention and Therapeutics (CVIT) has now proposed the expert consensus document for the management of acute myocardial infarction focusing on procedural aspect of primary PCI
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
Near Infrared Imaging Survey of Bok Globules: Density Structure
On the basis of near-infrared imaging observations, we derived visual
extinction (Av) distribution toward ten Bok globules through measurements of
both the color excess (E_{H-K}) and the stellar density at J, H, and Ks (star
count). Radial column density profiles for each globule were analyzed with the
Bonnor-Ebert sphere model. Using the data of our ten globules and four globules
in the literature, we investigated the stability of globules on the basis of
xi_max, which characterizes the Bonnor-Ebert sphere as well as the stability of
the equilibrium state against the gravitational collapse. We found that more
than half of starless globules are located near the critical state (xi_max =
6.5 +/- 2). Thus, we suggest that a nearly critical Bonnor-Ebert sphere
characterizes the typical density structure of starless globules. Remaining
starless globules show clearly unstable states (xi_max > 10). Since unstable
equilibrium states are not long maintained, we expect that these globules are
on the way to gravitational collapse or that they are stabilized by non-thermal
support. It was also found that all the star-forming globules show unstable
solutions of xi_max >10, which is consistent with the fact that they have
started gravitational collapse. We investigated the evolution of a collapsing
gas sphere whose initial condition is a nearly critical Bonnor-Ebert sphere. We
found that the column density profiles of the collapsing sphere mimic those of
the static Bonnor-Ebert spheres in unstable equilibrium. The collapsing gas
sphere resembles marginally unstable Bonnor-Ebert spheres for a long time. We
found that the frequency distribution of xi_max for the observed starless
globules is consistent with that from model calculations of the collapsing
sphere.Comment: Accepted for publication in the Astronomical Journal. 39 pages in
preprint format, including 10 figures. The version with higher resolution
figures can be obtained at the following site
(http://alma.mtk.nao.ac.jp/~kandori/preprint/
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