1,224 research outputs found
Partial Deconfinement
We argue that the confined and deconfined phases in gauge theories are
connected by a partially deconfined phase (i.e. SU(M) in SU(N), where M<N, is
deconfined), which can be stable or unstable depending on the details of the
theory. When this phase is unstable, it is the gauge theory counterpart of the
small black hole phase in the dual string theory. Partial deconfinement is
closely related to the Gross-Witten-Wadia transition, and is likely to be
relevant to the QCD phase transition.
The mechanism of partial deconfinement is related to a generic property of a
class of systems. As an instructive example, we demonstrate the similarity
between the Yang-Mills theory/string theory and a mathematical model of the
collective behavior of ants [Beekman et al., Proceedings of the National
Academy of Sciences, 2001]. By identifying the D-brane, open string and black
hole with the ant, pheromone and ant trail, the dynamics of two systems closely
resemble with each other, and qualitatively the same phase structures are
obtained.Comment: 27 pages, many figures. v2: reference updated, minor improvements.
v3: comments added. v4: version published in JHEP. A few comments and
references added. v5: Normalization error in eq.(14) has been corrected,
descriptions in Appendix B and Sec.3 have been corrected accordingly. A few
footnotes and references have been adde
Real-time Failure Monitoring System for High Power IGBT Under Acceleration Test Up to 500 A Stress
Real-time failure monitoring system for IGBT module was demonstrated under 500 A power cycling test. The system successfully captured internal phenomena occurred in interface regions of the device under test. Moreover, we proposed realtime failure analysis method by combining the real-time monitoring and image processing techniques. This failure analysis method enables to distinguish the place where degradation occurs in DUT and also trace internal degradation process to failure.2014 IEEE 26th International Symposium on Power Semiconductor Devices & IC\u27s (ISPSD), Jun 15-19, 2014, Hilton Waikoloa Village, Hawaii, US
Real Time Monitoring System for Internal Process to Failure of High Power IGBT
A real time failure analysis system for widely used high power IGBT modules is proposed, which enables to inspect internal process to failure of the devices under power stress test as a movie. This system was realized by combining a scanning acoustic tomography (SAT/SAM), power stress controlling, device cooling, water jet system and chip temperature monitoring. This system successfully obtained internal images of a DUT under the load current of 200A.2013 International Conference on Solid State Devices and Materials (SSDM2013), September 24-27, 2013, Hilton Fukuoka Sea Hawk, Fukuoka, Japa
3-D Kinematics of Water Masers in the W51A Region
We report proper motion measurements of water masers in the massive-star
forming region W51A and the analyses of the 3-D kinematics of the masers in
three maser clusters of W51A (W51 North, Main, and South). In W~51 North, we
found a clear expanding flow that has an expansion velocity of ~70 km/s and
indicates deceleration. The originating point of the flow coincides within 0.1
as with a silicon-monoxide maser source near the HII region W~51d. In W51 Main,
no systematic motion was found in the whole velocity range (158 km/s =< V(lsr)
=< -58 km/s) although a stream motion was reported previously in a limited
range of the Doppler velocity (54 km/s =< V(lsr) =< 68 kms). Multiple driving
sources of outflows are thought to explain the kinematics of W51 Main. In W51
South, an expansion motion like a bipolar flow was marginally visible. Analyses
based on diagonalization of the variance-covariance matrix of maser velocity
vectors demonstrate that the maser kinematics in W51 North and Main are
significantly tri-axially asymmetric. We estimated a distance to W51 North to
be 6.1 +/- 1.3 kpc on the basis of the model fitting method adopting a radially
expanding flow.Comment: 20 pages, 8 figures, 8 tables, appear in the NRO report No. 564
(ftp://ftp.nro.nao.ac.jp/nroreport/PASJ-W51.pdf) and will appear in Publ.
Astron. Soc. Japan, Vol. 54, No. 5 (10/25 issue
Linear Gyrokinetic Analyses of ITG Modes and Zonal Flows in LHD with High Ion Temperature
Ion temperature (Ti) gradient modes (ITG modes) and zonal flows for high Ti discharges in the Large Helical Device (LHD) are investigated by linear gyrokinetic Vlasov simulation. In recent LHD experiments, high Ti plasmas are generated by neutral beam injection, and spatial profiles of density fluctuations are measured by phase contrast imaging (PCI) [K. Tanaka et al., Plasma Fusion Res. 5, S2053 (2010)]. The observed fluctuations most likely propagate in the direction of the ion diamagnetic rotation in the plasma frame, and their amplitudes increase with the growth of the temperature gradient. The results show the characteristics of ITG turbulence. To investigate the ITG modes and zonal flows in the experiment, linear gyrokinetic simulations were performed in the corresponding equilibria with different Ti profiles by using the GKV-X code [M. Nunami et al., Plasma Fusion Res. 5, 016 (2010)]. The simulation results predict unstable regions for the ITG modes in radial, wavenumber, and phase velocity spaces, in agreement with the PCI measurements. Thus, the fluctuations observed in the experiment are attributed to ITG instability. The responses of the zonal flows show clear contrasts in different field spectra that depend on the Ti profile and the radial position. In addition to the dependence on the field spectra, the zonal flow residual levels are enhanced by increasing the radial wavenumber as theoretically predicted
Gehörlose Minderheiten und Menschenrechte : Ein Versuch zur Definition auf der Grundlage der gebärdensprachichen Kommunikation
Endoscopic and clinical evaluation of treatment and prognosis of Cronkhite-Canada syndrome: a Japanese nationwide survey.
BackgroundFirst reported in 1955, Cronkhite-Canada syndrome (CCS), a rare syndrome characterized by ectodermal abnormalities and inflammatory changes of the gastrointestinal tract mucosa, has been associated with a poor prognosis and life-threatening malignant complications. In a large population survey, we endeavored to characterize the course and treatment outcome of CCS through clinical and endoscopic assessment, and to explore its optimal treatment and surveillance strategy.MethodsA retrospective analysis of 210 patients with CCS was conducted via a questionnaire-based nationwide survey of 983 teaching hospitals located throughout Japan. We assessed clinical features, endoscopic findings, treatments used, and short- and long-term outcomes.ResultsThe average age at diagnosis was 63.5 years. In all cases, upper or lower gastrointestinal tract polyposis was confirmed, accompanied by characteristic ectodermal abnormalities. Of the treatments used, oral corticosteroids (30-49 mg/day) were the most effective treatment for active disease, with adjunctive nutritional support considered beneficial. With corticosteroid treatment, abdominal symptoms were relieved within a few months, whereas polyp regression often required more than 6 months. Maintenance of endoscopic remission with or without steroids for 3 years significantly lowered the development of CCS-related cancer, compared with relapsers or nonresponders, underscoring the importance of sustained endoscopic remission for cancer prevention.ConclusionsThe prognosis of CCS has greatly improved through the use of improved medical treatment. Although CCS continues to be relentlessly progressive, carrying a high cancer risk, a sufficient dose and duration of corticosteroid therapy accompanied by nutritional support and periodic endoscopic surveillance appears to improve its natural history
FACTOR ANALYSIS OF SPRINT PHASES ON THE SPEED CURVE OF THE 100M DASH
Previous studies have indicated that the speed curve of the 100m dash consists of some distinct phases which can be used to analyze an athlete's performance. The purpose of this study was to introduce a method using a portable computer as a device for the measurement of sprint time and the illustration of the speed curve, and to clarify a simple model of sprint phases on the factor structure. Based on the data of 133 participants, principal factor solution was given to the correlation matrix, and varimax rotation was applied to simplify the factorial structure of sprint phases. Finally, two factors were extracted and interpreted. It is suggested that this method is useful for measurement and evaluation in the 100m dash, and that a simple model of sprint phases may be explained by these two factors. These findings are important in predicting the ability of 100m sprinters and in considering coaching methods in terms of technique, training, strategy, etc
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