Thermally assisted quantum vortex tunneling in the Hall and dissipative regime

Quantum vortex tunneling is studied for the case where the Hall and the dissipative dynamics are simultaneously present. For a given temperature, the magnetization relaxation rate is calculated as a function of the external current and the quasiparticle scattering time. The relaxation rate is solved analytically at zero temperature and obtained numerically at finite temperatures by the variational method. In the moderately clean samples, we have found that a minimum in the relaxation rate exists at zero temperature, which tends to disappear with increase in the temperature.Comment: 18 pages, 9 figures, to be published in Phys. Rev.

A theoretical model for predicting Schottky-barrier height of the nanostructured silicide-silicon junction

ABSTRACT In this work, we have performed the first-principles calculations to investigate the Schottky barrier height (SBH) of various nanostructured silicide-silicon junctions. As for the silicides, PtSi, NiSi, TiSi2, and YSi2 have been used. We find that EFiF = EFi – EF, where EFi and EF are the intrinsic Fermi level of the semiconductor part and the Fermi level of the junction, respectively, is unchanged by nanostructuring. From this finding, we suggest a model, a symmetric increase of the SBH (SI) model, to properly predict SBHs of nanostructured silicide-silicon junctions. We also suggest two measurable quantities for the experimental validation of our model. The effect of our SI model applied to nanostructures such as nanowires and ultra-thin-bodies is compared with that of the widely used previous SBH model

Differential Spiral Joint Mechanism for Coupled Variable Stiffness Actuation

In this study, we present the Differential Spiral Joint (DSJ) mechanism for variable stiffness actuation in tendon-driven robots. The DSJ mechanism semi-decouples the modulation of position and mechanical stiffness, allowing independent trajectory tracking in different parameter space. Past studies show that increasing the mechanical stiffness achieves the wider range of renderable stiffness, whereas decreasing the mechanical stiffness improves the quality of actuator decoupling and shock absorbance. Therefore, it is often useful to modulate the mechanical stiffness to balance the required level of stiffness and safety. In addition, the DSJ mechanism offers a compact form factor, which is suitable for applications where the size and weight are important. The performance of the DSJ mechanism in various areas is validated through a set of experiments

B+-tree Index Optimization by Exploiting Internal Parallelism of Flash-based Solid State Drives

Previous research addressed the potential problems of the hard-disk oriented design of DBMSs of flashSSDs. In this paper, we focus on exploiting potential benefits of flashSSDs. First, we examine the internal parallelism issues of flashSSDs by conducting benchmarks to various flashSSDs. Then, we suggest algorithm-design principles in order to best benefit from the internal parallelism. We present a new I/O request concept, called psync I/O that can exploit the internal parallelism of flashSSDs in a single process. Based on these ideas, we introduce B+-tree optimization methods in order to utilize internal parallelism. By integrating the results of these methods, we present a B+-tree variant, PIO B-tree. We confirmed that each optimization method substantially enhances the index performance. Consequently, PIO B-tree enhanced B+-tree's insert performance by a factor of up to 16.3, while improving point-search performance by a factor of 1.2. The range search of PIO B-tree was up to 5 times faster than that of the B+-tree. Moreover, PIO B-tree outperformed other flash-aware indexes in various synthetic workloads. We also confirmed that PIO B-tree outperforms B+-tree in index traces collected inside the Postgresql DBMS with TPC-C benchmark.Comment: VLDB201

Study on Replacement Plan with Statistical Analysis for Water Distribution Pipelines

首都大学東京, 2014-09-30, 博士(工学), 甲第414号首都大学東

Physics data management tools: computational evolutions and benchmarks

The development of a package for the management of physics data is described: its design, implementation and computational benchmarks. This package improves the data management tools originally developed for Geant4 physics models based on the EADL, EEDL and EPDL97 data libraries. The implementation exploits recent evolutions of the C++ libraries appearing in the C++0x draft, which are intended for inclusion in the next C++ ISO Standard. The new tools improve the computational performance of physics data management.Comment: 6 pages, to appear in proceedings of the Joint International Conference on Supercomputing in Nuclear Applications and Monte Carlo 2010 (SNA + MC2010

A Case Study of Health Tourism in the Jeju Province, South Korea

The United States Census Bureau (2006) reported that in 2005 more than 46 million Americans lacked health insurance, and that by 2019 national spending for health care would exceed $4.5 trillion (Centers for Medicare & Medicaid Services, 2010). Because those numbers are expected to increase, health tourists are seeking better opportunities for low-cost, high-quality treatment in other countries, plus the added benefit of experiencing foreign cultures. Health tourism is a rapidly growing market in both advanced and developing countries. The purpose of this study was to develop an applicable model of health tourism, the Jeju-Style Health Tourism Model, for Jeju Special Self-Governing Province, in the Republic of Korea (South Korea) and to provide other cities and countries with its implications. This study employed a focus group, indepth interviews, and content analysis to discover important factors in developing the model. The results suggested that four major sources must be executed together to maximize the benefits of health tourism development. On a foundation of natural resources, knowledge-based resources were most important (54.5%), followed by artificial resources (25.7%), and expenses-based resources (19.8%)

Analysis of user requirement on U-Healthcare system

Abstract The objective of this study was to explore and connect the relation between independent variables of Health Promotion Model (HPM) and customers" demand for developing ubiquitous healthcare (u-Healthcare) system and then, to suggest the methods applicable to the system design. After identifying performance levels and influence coefficients of every variables and applying them to Quality Function Deployment (QFD) to find out the relation between the requirements and customers" demand of u-Healthcare System, it sets the main goal in determining what are important system characteristics for effective quality improvement. First, it applied structural equation modeling (SEM) to search for multiple independent variables influencing user"s intention. Second, with the findings, this study has also its significance in suggesting techniques applicable to the u-Healthcare system development using QFD. Concretely, by investigating u-Healthcare users" direct requirement attributes and extracting u-Healthcare system service characteristics with customer requirement reflected by using QFD model, this study figured out the order of priority in the importance of system characteristics that must be dealt with most importantly. As a result of analysis, this study proposed an application method of QFD to satisfy customer requirements for the development of u-Healthcare system. Finally, the result could give important features to improve users" requirements by using this process

Bacterial strategies along nutrient and time gradients, revealed by metagenomic analysis of laboratory microcosms

There is considerable interest in the functional basis of ecological strategies amongst bacteria. We used laboratory microcosms based on culturing of elutant from soil, to study the effects of varying initial nutrient concentration, and time succession, on the community metagenome. We found a distinct set of nutrient related or time related changes in the functional metagenome. For example a high nutrient (copiotrophic) strategy was associated with greater abundance of genes related to cell division and cell cycle, while a low nutrient (oligotrophic) strategy had greater abundance of genes related to carbohydrate metabolism and virulence, disease and defense. We also found time related changes in the functional metagenome, revealing a distinct ‘r’ related strategy with greater abundance of genes related to regulation and cell signaling, and a ‘K’ strategy rich in motility and chemotaxis related genes. These different gene-based strategies may help to explain how so many bacterial OTUs coexist in nature, and the functional principles dominating natural communities. In terms of diversity, both the OTU richness and the richness of species assignment of functional genes showed linear correlations with functional gene richness, supporting the hypothesis that greater taxonomic diversity is associated with greater functional diversity, with possible implications for ecosystem stability