Dynamics of colliding branes and black brane production

We study the dynamics of colliding domain walls including self-gravity. The initial data is set up by applying a BPS domain wall in five-dimensional supergravity, and we evolve the system determining the final outcome of collisions. After a collision, a spacelike curvature singularity covered by a horizon is formed in the bulk, resulting in a black brane with trapped domain walls. This is a generic consequence of collisions, except for non-relativistic weak field cases, in which the walls pass through one another or multiple bounces take place without singularity formation. These results show that incorporating the self-gravity drastically changes a naive picture of colliding branes.Comment: 5 pages, 5 figures references adde

Estimation of mutual information via quantum kernel method

Recently, the importance of analysing data and collecting valuable insight efficiently has been increasing in various fields. Estimating mutual information (MI) plays a critical role to investigate the relationship among multiple random variables with a nonlinear correlation. Particularly, the task to determine whether they are independent or not is called the independence test, whose core subroutine is estimating MI from given data. It is a fundamental tool in statistics and data analysis that can be applied in a wide range of application such as hypothesis testing, causal discovery and more. In this paper, we propose a method for estimating mutual information using the quantum kernel. We investigate the performance under various problem settings, such as different sample size or the shape of the probability distribution. As a result, the quantum kernel method showed higher performance than the classical one under the situation that the number of samples is small, the variance is large or the variables posses highly non-linear relationships. We discuss this behavior in terms of the central limit theorem and the structure of the corresponding quantum reproducing kernel Hilbert space.Comment: 20 pages, 10 figure

Experiment and numerical simulation of the combined effect of winding, cool-down, and screening current induced stresses in REBCO coils

This paper overviews the combined effects of winding, cool-down, and screening current-induced stresses in REBCO coils. First, a simulation method to model the circumferential stress modification effect due to the screening-current is overviewed. The simulation includes coil winding, cooling down, and coil charge up to the operating current. Second, we will compare the numerical simulation results with the experimental results. The numerical simulations for a dry coil and an epoxy impregnated coil agree well with the experimental results. Third, the enhanced circumferential stress did not degrade the performance of a dry winding REBCO coil, but the improved increased compressive stress buckled the coil structure. Finally, it is demonstrated that epoxy impregnation has beneficial effects in reducing the stress modification effect. However, the circumferential stress is enormously enhanced at the coil ends, sometimes resulting in degradation of the coil performance

Modeling the current distribution in HTS tapes with transport current and applied magnetic field

A numerical model is developed for the current distribution in a high temperature superconducting (HTS) tape, (Bi,Pb)2Sr2 Ca2Cu3Ox-Ag, subjected to a combination of a transport current and an applied magnetic field. This analysis is based on a two-dimensional formulation of Maxwell's equations in terms of an integral equation for the current density J. The finite thickness of the conductor and an arbitrary voltage-current relation (e.g. n-power relation, magnetic field dependency) for the conductor are included in the model. Another important feature is that the model also covers an applied magnetic field in arbitrary directions and a rotating field perpendicular to the conductor, which is of great interest for analyzing the AC loss of HTS (transformer) coils or three-phase electric power cables. A comparison is made with transport current loss measurements on an HTS tape with an AC applied fiel

QAC RESISTANCE OF P. AERUGINOSA

The adaptation mechanism of Pseudomonas aeruginosa ATCC 10145 to quaternary ammonium compounds (QACs) was investigated. A P. aeruginosa strain with adapted resistance to QACs was developed by a standard broth dilution method. It was revealed that P. aeruginosa exhibited remarkable resistance to N-dodecylpyridinium iodide (P-12), whose structure is similar to that of a common disinfectant, cetylpyridinium chloride. Adapted resistance to benzalkonium chloride (BAC), which is commonly used as a disinfectant, was also observed in P. aeruginosa. Moreover, the P-12-resistant strain exhibited cross-resistance to BAC. Analysis of the outer membrane protein of the P-12-resistant strain by two-dimensional polyacrylamide gel electrophoresis showed a significant increase in the level of expression of a protein (named OprR) whose molecular mass was approximately 26 kDa. The actual function of OprR is not yet clear; however, OprR was expected to be an outer membrane-associated protein with homology to lipoproteins of other bacterial species, according to a search of the National Center for Biotechnology Information website with the BLAST program by use of the N-terminal sequence of OprR. A correlation between the level of expression of OprR and the level of resistance of P. aeruginosa to QACs was observed by using a PA2800 gene knockout mutant derived from the P-12-resistant strain. The knockout mutant recovered susceptibility not only to P-12 but also to BAC. These results suggested that OprR significantly participated in the adaptation of P. aeruginosa to QACs, such as P-12 and BAC

Rapid screening method for detecting highly pathogenic Streptococcus intermedius strains carrying a mutation in the lacR gene

Streptococcus intermedius is a member of the normal human commensal flora and secretes a human-specific cytolysin intermedilysin (ILY) as a major virulence factor. Expression of ily is repressed by LacR and loss-of-function mutations of LacR are observed in many ILY high-producing strains isolated from deep-seated abscesses, suggesting that high ILY production is necessary for increased virulence. However, because ILY exhibits no β-hemolysis on animal blood agar plates, differentiating ILY high- and low-producing strains using conventional laboratory methods is not possible. Interestingly, S. intermedius also produces glycosidases, including MsgA and NanA, which exhibit N-acetyl-β-D-glucosaminidase and neuraminidase activities, respectively. Moreover, MsgA expression, but not NanA, is negatively regulated by LacR. Here we measured the activities of MsgA, NanA and ILY in strains isolated from clinical specimens and dental plaque to determine the correlation between these glycosidase activities and ILY hemolytic activity. Hemolytic activity showed a strong positive correlation with MsgA and a weak negative correlation with NanA activities. Therefore, we calculated the ratio of MsgA and NanA activity (M/N ratio). This value showed a stronger positive correlation (r = 0.81) with ILY hemolytic activity and many strains with high M/N ratios (> 2) were ILY high-producers with loss-of-function mutations in LacR.Rapid screening method for highly pathogenic S. intermedius strains based on the ratio of activities of MsgA and NanA resulting from lacR mutations

Application of Electron Beam Melting to the Removal of Phosphorus from Silicon: Toward Production of Solar-Grade Silicon by Metallurgical Processes

Removal methods of impurity from metallurgical-grade silicon (Si) are intensively studied to produce solar-grade silicon (SoG-Si) with a smaller economical load and lower cost. Removal of phosphorus (P) has been an important issue because of difficulties in application of conventional metallurgical methods such as solidification refining. Because P evaporates preferentially from molten Si due to its high vapor pressure, electron beam (EB) melting has been applied to the purification of Si. The evaporation of impurity P from Si is considered based on previous thermodynamic investigations here, and several research reports on EB melting of Si are reviewed