A new technology for the production of aluminum matrix composites by the plasma synthesis method

Aluminum matrix composites were produced via the plasma injection of reinforcing particulates into aluminum melts stirred electromagnetically. In this process, a metallic wire supplied to the active zone of plasma torch disintegrated into fine metallic particles. In the plasma arc, the particles are heated above the melting point and accelerated to close to sonic speed, which helps with the incorporation of the particles into the melt. In this study, the possibility of producing aluminum matrix composites reinforced by intermetallic compound particles via plasma synthesis is demonstrated.     

Modeling of extraction behavior of docosahexaenoic acid ethyl ester by utilizing slug flow prepared by microreactor

The liquid–liquid extraction dynamics of an ethyl ester of docosahexaenoic acid (DHA‐Et) with silver ion was investigated. The kinetic model was derived according to the following stepwise processes: Diffusion of DHA‐Et across the organic film, complex‐formation between DHA‐Et and silver ion at the interface, and diffusion of extracted complex across the aqueous film. The kinetic parameters for the complex‐formation reaction were determined from the investigation with the stirred transfer cell. With the proposed model and determined parameters, we predicted the uptakes of DHA‐Et for the extraction system utilizing a slug flow prepared by a microchip. The calculated uptakes showed good correlation to the experimental data. The theoretical investigation suggested that the fast equilibration realized for the slug flow extraction system was due to the large specific interfacial area of the slug caused by the presence of wall film and the thin liquid film caused by the internal circulation. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

Molecular biology of oxygen tolerance in lactic acid bacteria: Functions of NADH oxidases and Dpr in oxidative stress

Lactic acid bacteria including Streptococcus mutans lack cytochromes and heme-containing proteins. Most lactic acid bacteria also lack catalase. However, they can grow in the presence of air. In view of the defense against oxygen toxicity, the lack of catalase in lactic acid bacteria is not always consistent with its aerotolerance. Mechanisms, by which lactic acid bacteria establish their growth in air, are therefore an active area of investigation. We identified two kinds of NADH oxidase genes, nox-1 and nox-2 for H2O2-forming NADH oxidase (Nox-1) and H2O-forming NADH oxidase (Nox-2), respectively, in S. mutans and found that Nox-1 is homologous with flavoprotein component, AhpF, of Salmonella typhimurium alkyl hydroperoxide reductase (AhpR), consisting of AhpF and AhpC. We also identified ahpC which is homologous with ahpC of S. typhimurium, upstream of nox-1 in S. mutans. In the first and second parts of this article, we will refer to the role of Nox-1 which acts together with AhpC as bi-component peroxidase system in S. mutans, catalyzing the NADH-dependent reduction of organic hydroperoxides or H2O2 to their respective alcohol and/or H2O. We will also refer to the role of Nox-2 in carbohydrate metabolism of S. mutans in its aerobic life. Nox-2 was found to be involved in regenerating NAD+, which is required for glycolysis in S. mutans. While studying nox-1 and ahpC double deletion mutant of S. mutans, we found that the mutant still showed the same level peroxide tolerance as did the wild-type strain. The finding suggested the existence of another antioxidant system in addition of Nox-1 and AhpC in S. mutans. We identified a new gene, dpr (for Dps-like Peroxide Resistance gene) and its product, Dpr, as an iron-binding protein which is responsible for oxygen tolerance in S. mutans. In the third part of this article, we will refer to the current status of knowledge of molecular cloning of dpr, the characteristics of dpr-disruption mutants, and a mechanism by which Dpr confers aerotolerance to S. mutans.     

Adaptation technique for integrating genetic programming and reinforcement learning for real robots

We propose an integrated technique of genetic programming (GP) and reinforcement learning (RL) to enable a real robot to adapt its actions to a real environment. Our technique does not require a precise simulator because learning is achieved through the real robot. In addition, our technique makes it possible for real robots to learn effective actions. Based on this proposed technique, we acquire common programs, using GP, which are applicable to various types of robots. Through this acquired program, we execute RL in a real robot. With our method, the robot can adapt to its own operational characteristics and learn effective actions. In this paper, we show experimental results from two different robots: a four-legged robot "AIBO" and a humanoid robot "HOAP-1." We present results showing that both effectively solved the box-moving task; the end result demonstrates that our proposed technique performs better than the traditional Q-learning method.     

Average thresholds in the 8 to 20 kHz range in young adults

RATIONALE AND OBJECTIVES: The Comprehensive Clinical Assessment (CCA) examination at the University of Michigan Medical School is a series of test stations through which the mastery of clinical skills is evaluated. The purpose of this study was to determine whether student performance on the radiology station improved in years when radiology faculty presented case-of-the-week unknowns to the 3rd-year students. MATERIALS AND METHODS: The authors compared four separate classes of medical students in examination years 1993, 1994, 1995, and 1996 by using the total CCA examination score, the radiology station score, and radiology station pass/fail rates. Radiology case-of-the-week presentations were given by the radiology faculty only in academic years 1993-1994 and 1994-1995 (examination years 1994 and 1995). RESULTS: The means and standard deviations of the radiology station scores for the examination years when case-of-the-week presentations were not given, 1993 and 1996, were 78.92 +/- 13.62 and 79.76 +/- 13.62, respectively. In the years case-of-the-week presentations were given, 1994 and 1995, the radiology station scores averaged 90.83 +/- 8.58 and 89.97 +/- 9.66, respectively (P < .001, global alpha = .05). Total CCA percentage correct scores were similar for all years studied. In 1993 and 1996, 7.6% and 5.3% of students, respectively, failed the radiology station. In 1994 and 1995, 0.4% and 0% of students, respectively, failed (P < .0001). CONCLUSION: Case-of-the-week presentations by radiology faculty increased 3rd-year students' basic radiologic knowledge as evidenced by increased scores on the radiology station of the CCA examination.     

Initial weight computation method with rapid convergence for adaptive array antennas

This paper presents a rapid initial weight computation method for adaptive array antennas. The proposed method estimates a correlation matrix and a correlation vector, where the correlation matrix is estimated using not only received samples with the desired signal, but also those before starting the transmission of the desired signal. The proposed method reduces the number of known symbols required for weight convergence. Furthermore, the combined use of the proposed method and the decision-feedback minimum mean square error combining method significantly improves weight convergence. Numerical results show that the combined method converges an array with sixteen antennas by using less than ten known symbols.     

A case report of angiomyolipoma arising from the renal capsule

A case of angiomyolipoma arising from the renal capsule is reported. A 49-year-old female was admitted to our hospital with a complaint of abdominal mass pointed out by ultrasonography during her yearly health check. The tumor was 10 cm in size. On abdominal enhanced CT, the tumor was existed behind the left kidney. The capsule of the tumor was enhanced and the septums were seen inside of the tumor. MRI revealed a hemorrhage in the tumor and selective renal angiography showed the tumor was fed by the renal capsular artery. A tumor of the renal capsule was suspected and a laparotomy was done. Pathological results by the frozen section suggested malignancy and radical nephrectomy was performed. Angiomyolipoma was diagnosed histologically. Tumors of the renal capsule are uncommon and angiomyolipoma of the renal capsule is extremely rare. We have found only two cases in Japanese medical literature.     

Linewidth-tolerant 30 Gbit/s 8-PSK self-homodyne using single modulator and phase-noise cancelling technique

Linewidth-tolerant 8-ary phase-shift keying (8-PSK) self-homodyne modulation/demodulation at symbol rates of 10 Gsymbol/s (30 Gbit/s) and 1 Gsymbol/s (3 Gbit/s) using a distributed-feedback laser diode with a linewidth of 30 MHz and a single modulator is experimentally demonstrated. Owing to the phase-noise cancelling capability of the self-homodyne scheme based on a polarisation-multiplexed pilot-carrier, a floorless bit error rate performance of <10^-9 was achieved; this value was obtained even for the symbol rate of 1 Gsymbol/s, at which the required linewidth condition is stringent. Furthermore, the tolerances against differential group delays and dispersion at the symbol rate of 10 Gsymbol/s have been evaluated.     

First plasma experiment on spherical tokamak device UTST

The UTST (University of Tokyo Spherical Tokamak) device was constructed for the purpose of exploring the formation of ultrahigh‐beta ST (spherical tokamak) plasma using the double null plasma merging method. When two plasmas merge together to form a single plasma, magnetic field lines reconnect, and magnetic field energy is converted to plasma kinetic energy, increasing the plasma beta. Merging start‐up has been demonstrated in the TS‐3/4, START, and MAST devices using coils inside the vacuum vessel, and the TS‐3 plasma obtained a 50% beta. In order to demonstrate start‐up in a more reactor‐relevant situation, UTST has all poloidal field (PF) coils outside the vacuum vessel. The first plasma experiment on the UTST was begun in December 2007. In the results, the plasma obtained 10 kA by using only the outer PF coils and a single ST was generated in the lower area (z = –0.3 to –1.0 m) close to a washer gun. This result suggests that another washer gun on the top of the UTST can allow the generation of ST in the upper area and merging start‐up by using outer PF coils. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 179(2): 20–26, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21216