Implementation of muon interaction models in PHITS

We have constructed models for muon interactions (i.e., bremsstrahlung, electron–positron pair production, muon photonuclear interaction, and negative muon capture reaction) and implemented these models in the particle and heavy ion transport code system (PHITS). The PHITS2.86 agrees well with experimental data for the vertical intensities of cosmic-ray muons in water and standard rock. The calculated results for neutron production by muon photonuclear interaction and negative muon capture reaction are in good agreement with measured data, except in the case of lead target. PHITS2.86 can also reproduce the cross-section of radionuclide production by muons passing through a concrete wall very well. These results indicate the applicability of PHITS2.86 to the shielding design of muon facilities in which estimations of attenuation length and induced radioactivity are important.     

Very fast generation of content-preserved photo collage under canvas size constraint

Photo collage, which constructs a compact and visually appealing representation from a collection of input images, can offer a most convenient and impressive user experience. Most previous approaches to collage construction have utilized saliency detection and visibility optimization. However, such methods are computationally expensive and not feasible for real-time applications such as online image retrieval or interactive photo browsing. Moreover, the effectiveness of automatic saliency detection may be questionable. Even if the main regions of interest are retained accurately, some visually not salient but semantically important items such as logos, captions, and copyright information located at the margins and corners may be missed. In our alternative approach, we address the issue of content-preserved collage, which avoids content-harmful processes such as cropping or changes to aspect ratio and orientation. Based on a full balanced binary layout tree, our algorithm can pack all the input images tightly onto the collage canvas while keeping their visual information unchanged. The proposed algorithm is fast, requiring less than 0.5 ms to generate a 100-image collage. We also present several extensions and applications oriented to a variety of usage contexts and device platforms.     

Adaptive-integration-time image sensor with real-time reconstruction function

A computational image sensor is proposed in which the pixel controls its integration time to light intensity. The integration time of each pixel is selected from among several lengths of integration time and the integration time is shortened if the pixel intensity becomes saturated. Although the integration time of each pixel varies, the pixel intensity is adjusted on the sensor in real time. The dynamic range of the pixel value output from the proposed sensor is greatly widened. A prototype of 64/spl times/48 pixels has been fabricated by using 2-poly 2-metal 0.8-/spl mu/m CMOS process. The proposed sensor has simple functions for the comparison of intermediate integration value and threshold to control the integration time and nonlinear image reconstruction. Because the maximum number of the comparison-reset operations during a frame is three, one of the four integration times can be selected pixel by pixel. The circuit and layout design of the prototype which has computational elements based on column parallel architecture are described and the fundamental functions have been verified. By the experiments, it has been verified that the sensor can achieve a wide dynamic range by adapting to light.     

Comparison of arrhythmogenicity of atrial pacing at several right atrial pacing sites: evaluation of canine atrial electrograms during atrial pacing and arrhythmogenicity for atrial fibrillation

The changes in the duration of atrial electrograms and the appearance of AF during atrial pacing were compared among five atrial pacing sites in dogs to clarify the arrhythmogenicity of atrial pacing at different atrial pacing sites. In seven mongrel dogs (15-20 kg), the right atrial surface was exposed by right thoracotomy. Atrial electrograms were recorded via bipolar electrodes with an interelectrode distance of 1.2 mm at four right atrial sites: (1) the high right atrium (HRA), (2) the mid-right atrium (MRA), (3) the low right atrium (LRA), and (4) the center of the pectinate muscle (PM). The duration of the atrial electrograms at these four recording sites were measured during atrial pacing with fixed cycle lengths of 200, 150, and 120 ms delivered at five atrial sites: (1) the HRA, (2) the inferior vena cava (IVC), (3) the right atrial appendage (RAA), (4) Bachman's bundle (BB), and (5) the atrial septum (AS). In each dog, the atrial pacing with the 120-ms cycle length was performed five times at each pacing site to evaluate the inducibility of AF. When AF was induced, the atrial recording site which first showed a fragmented atrial electrogram was considered the initiation site of the AF. AF was induced during 9 of 35 episodes of atrial pacing at the HRA site, 11 of 35 at the IVC site, 5 of 35 at the RAA site, 3 of 35 at the BB site, and none at the AS site. The initiation site of AF was in the HRA site in 11 of 28 episodes of induced AF, in the MRA site in 9 of 28, and in the LRA site in 8 of 28. At each recording site, the shorter the paced cycle length, the longer the duration of the atrial electrogram regardless of the pacing site. During the atrial pacing with the 200-ms cycle length, the HRA pacing resulted in the shortest duration of the atrial electrogram at each recording site in comparison with the other pacing sites. However, during atrial pacing at the two shorter paced cycle lengths, the duration of the atrial electrogram was shorter during the pacing at the BB or AS sites in comparison with the other three pacing sites, i.e., the HRA, IVC, and RAA sites. These results were the same for all atrial recording sites, but the prolongation of the atrial electrogram was most prominent at the HRA and MRA recording sites, which are most likely initiation sites of the induced AF. In the canine atria, (1) the initiation sites of AF were likely to be the HRA, MRA, or LRA sites in comparison with the PM site; and (2) the atrial pacing at the BB or AS sites was considered less arrhythmogenic for AF than the pacing at the HRA, LRA, or RAA sites.     

Modeling creep damage based on real microstructure

This paper outlines a method to model creep failure of polycrystalline materials based on a real microstructure taken from an optical microscope. The creep failure is simulated in 304 stainless steel and the simulation is based on Norton’s creep law. By treating the grain boundaries and the grains differently and adopting the void nucleation process proposed by Shewmon, the creep strain energy density can be used as a failure criterion. The result of the simulation confirmed the results of conventional methods used in a high-temperature remnant life assessment. The intermediate results of the simulation process allow calculation/monitoring of stiffnesses degradation as the material undergoes creep failure.     

R&D activities based on fast reactor cycle technologies for transmutation of TRU and LLFP by JNC

Research and development(R&D) activities on partitioning and transmutation of trans-uranium nuclides (TRU) and LLFP and future R&D program in JNC were summarized. Feasibility design studies have been conducting to investigate the characteristics of a fast reactor core with TRU and LLFP transmutation. It was reconfirmed that the fast reactor has a strong potential for transmuting TRU and LLFP, effectively. R&D for establishing partitioning process of TRU apart from the high-level radioactive wastes have been carried out. By several counter-current runs of the TRUEX process using highly active raffinates, a process flow sheet capable of selective partitioning of actinides and fission products was newly developed. JNC has settled a new R&D program concerning partitioning and transmutation of long-lived radioactive waste based on recommendation of check & review for OMEGA program performed by the Ad Hoc Committee under the Atomic Energy Commission of Japan (AEC). The R&D program is composed of the design studies and development of element technologies (fabrication, irradiation) in the “Feasibility Studies” on commercialized fast reactor system and the basic studies with experiments (nuclear data, reactor physics, fuel property, etc.) to establish database and analytical tools for the TRU- and LLFP- containing fuel and core design.     

Self-Lubrication of Chlorine-Implanted Titanium Nitride Coating

Chlorine implantation into TiN coatings decreases the wear loss and the friction coefficient. Even by low-dose chlorine implantation, the wear volume is decreased by three orders of magnitude or more, and the friction coefficient becomes <0.1. This self-lubrication mechanism is related to the presence and mobility of implanted chlorine atoms inside the columnar TiN microstructure. According to observations of chlorine-implanted TiN coatings using high-resolution transmission electron microscopy, the chlorine atoms are present in the damaged region, where TiN is composed of nanosized grains. From these data, a self-lubrication mechanism is proposed with chlorine catalyzing the oxidation of titanium and leading to the formation of some tribological reaction product.     

Cystic renal cell carcinoma: arose as a simple cyst, recurred repeatedly as a multicystic mass and finally presented as a solid mass

AIMS: (1) To make precise measurements and comparisons of various aspects of motility of three gastrointestinal pathogens, Helicobacter pylori, Campylobacter jejuni, and Escherichia coli, in log phase growth; (2) to provide background information on motility data to study the influence of pH, viscosity, and chemotactic factors, thereby gaining a better understanding of bacterial pathogenesis. METHODS: Computer image processing technology and phase contrast microscopy (Hobson BacTracker) were used to measure several indices of bacterial motility in real time. Ten clinical isolates of each species in log phase liquid culture were studied. RESULTS: C jejuni moved fastest, with a median curvilinear velocity (CLV) of 38.76 microns/s (range 29.08 to 52.82). Next was H pylori, median CLV 25.02 microns/s (range 12.07 to 29.07). E coli was the slowest, median CLV 12.73 microns/s (range 8.20 to 18.04). The straight line velocities showed similar trends. Measurement of track linearity (TL) showed that C jejuni moved the straightest (TL 60.3%), H pylori moved in wide circles (TL 28.7%), and E coli showed spinning movement without much linear displacement (TL 18.3%). There were significant differences in these three variables between the species studied, but no significant differences in measurements of time and frequency of halts between movement runs. CONCLUSIONS: The BacTracker provides a useful technical aid for measuring several indices of bacterial motility objectively, reproducibly, and precisely, which is difficult to achieve without computer assistance. Accurate quantification of motility provides a basis for studying the factors which influence bacterial motility. It can provide phenotypic measurements of the effect of flagellar gene depletion.     

Normal and anormal microstructure of plasma nitrided Fe-Cr alloys

Plasma nitriding behavior of Fe-Cr alloys has been studied at temperatures in the range of 773–873 K in order to provide basic knowledge for microstructure design of nitrided layers and to improve the wear resistance. In the nitriding temperature of 773 K, typical microstructure of nitrided layers was observed as reported elsewhere. However, anormal microstructure of nitrided layers was observed under a nitriding condition, at 873 K for 176.4 ks (49 h). In Fe-13Cr alloy, nitrided layer showed stripe-pattern, each sub-layer of which has different chromium content. Nitrided layer hardness increased gradually from the specimen surface to the nitriding front before dropping drastically to the same level as matrix hardness. The stripe-pattern was also observed for Fe-3Cr alloy at the vicinity of nitriding front for the same nitriding conditions. On the other hand, nitrided layers in Fe-8Cr and Fe-19Cr alloys are composed from different sub-layers, containing different concentration of chromium. These phenomena cannot be explained only by nitrogen diffusion process during the nitriding.