Efficient Excitation of Hybrid Modes in a THz Clinotron

Journal of Infrared, Millimeter, and Terahertz Waves - Various regimes of hybrid, bulk-surface, modes being excited in the clinotron oscillator with a sheet electron beam and nonuniform grating...     

Change in bacterial community during biodegradation of aniline

A modification of the standard electrodiagnostic test was developed in an effort to provide a more sensitive electrodiagnostic evaluation in radial tunnel syndrome. Radial motor nerve latency recordings were obtained in 3 different forearm positions: neutral, passive supination, and passive pronation. The maximal difference in these recordings, the differential latency, in 25 patients with radial tunnel syndrome of greater than 6 months duration (test group) was compared with those in 25 asymptomatic volunteers (control group). Differential latency recordings were obtained in all patients in the test group before and after surgery. Radial nerves that were compressed demonstrated a significantly greater differential latency (0.44+/-0.12 ms) versus controls (0.12+/-0.008 ms). Following radial nerve decompression, differential motor latencies in the test group decreased below control values, demonstrating a resolution of the provoked electrical response with a postoperative differential latency of 0.07+/-0.05 ms. Our results demonstrate the differential motor latency of the radial nerve to be a sensitive electrodiagnostic tool in patients with radial tunnel syndrome. A differential latency of > or =0.30 ms was considered indicative of radial tunnel syndrome.     

The role of prostate specific antigen in diagnosis of localized adenocarcinoma of the prostate. Nara Uro-Oncology Research Group

The number of cases of prostate carcinoma (PCA) is steadily inceasing in Japan. The clinical application of a reliable tumor marker, prostate specific antigen (PSA) for the diagnosis, as well as the increasing elderly population in Japan may account for this increase. The subjects were patients at the Nara Medical University and its affiliated hospitals; 1) 687 cases without PCA were evaluated for age-specific PSA and the incidence of abnormal PSA following urological manipulations, 2) 135 cases with histological proven BPH by transurethral resection of prostate (TUR-P) were examined for PSA density (PSAD) and positive PSA rate in BPH, 3) 135 cases receiving a needle biopsy with suspicion of PCA were examined for the efficacy of PSA and PSAD and other parameters, and 4) 459 PCA cases treated between 1988 and 1994, were examined for specific PSA and PSAD values by stage and degree of cell differentiation. The PSA assay used in this study was MARKIT-M PA (normal range < or = 3.6 ng/ml). The PSA was decreased gradually with age in non-PCA patients, and abnormal PSA was found in 5.5% of these patients following manipulations. The average PSA was 2.95 +/- 2.03 ng/ml in 130 BPH patients (mean age: 71.1 +/- 7.0 years old. and average prostate volume: 32.9 +/- 16.1 ml). And abnormal PSA level (more than 3.61 ng/ml) was found in 22.3%. The mean PSAD was 0.1.0 +/- 0.06, and PSAD was below 0.15 in 86.1% of these BPH cases. Among the 135 cases receiving a needle biopsy, 33 cases had PSA values between 3.61 and 10.0 ng/ml. Of these cases, PCA was found in 18.5% of the 27 cases with a PSAD below 1.5, and in 33.3% of the 6 cases with a PSAD over 1.5. PSA and PSAD were proportionally increased with stage, and a significant difference in the PSA value was observed between stage B1 and B2, and stage C and D (P < 0.05). However, PSA and PSAD values were not significantly correlated with the cell differentiation in PCA stage A2-C. In total, PSA was 18.1 ng/ml in well, 23.9 ng/ml in moderately and 35.9 ng/ml in poorly differentiated type PCA. The positive rate of PSA was 22.3, 65.4 and 83.5%, that of prostate acid phosphatase (PAP) was 10.0, 17.8 and 45.8%, and that of GSM was 25.0, 14.7 and 68.4%, in BPH, stage A PCA and stage BPCA, respectively. In conclusion, PSA is the most reliable tool in the diagnosis of localized PCA. However, the differential diagnosis of BPH and localized PCA is difficult when the PSA value is between 3.61 and 10.0 ng/ml, and accurate staging of localized PCA is difficult with PSA or PSAD alone. At present, it is necessary to use all possible tools for the early detection of localized PCA, and to perform the needle biopsy in all PCA-suspicious cases.     

Purification and characterization of a novel ceramidase from Pseudomonas aeruginosa

We report here a novel type of ceramidase of Pseudomonas aeruginosa AN17 isolated from the skin of a patient with atopic dermatitis. The enzyme was purified 83,400-fold with an overall yield of 21.1% from a culture supernatant of strain AN17. After being stained with a silver staining solution, the purified enzyme showed a single protein band, and its molecular mass was estimated to be 70 kDa on SDS-polyacrylamide gel electrophoresis. The enzyme showed quite wide specificity for various ceramides, i.e. it hydrolyzed ceramides containing C12:0-C18:0 fatty acids and 7-nitrobenz-2-oxa-1, 3-diazole-labeled dodecanoic acid, and not only ceramide containing sphingosine (d18:1) or sphinganine (d18:0) but also phytosphingosine (t18:0) as the long-chain base. However, the enzyme did not hydrolyze galactosylceramide, sulfatide, GM1, or sphingomyelin, and thus was clearly distinguished from a Pseudomonas sphingolipid ceramide N-deacylase (Ito, M., Kurita, T., and Kita, K. (1995) J. Biol. Chem. 270, 24370-24374). This bacterial ceramidase had a pH optimum of 8.0-9.0, an apparent Km of 139 microM, and a Vmax of 5.3 micromol/min/mg using N-palmitoylsphingosine as the substrate. The enzyme appears to require Ca2+ for expression of the activity. Interestingly, the 70-kDa protein catalyzed a reversible reaction in which the N-acyl linkage of ceramide was either cleaved or synthesized. Our study demonstrated that ceramidase is widely distributed from bacteria to mammals.     

Crystallographic Texture Development in Bismuth Sodium Titanate Prepared by Reactive-Templated Grain Growth Method

Bi_0.5Na_0.5TiO₃ (BNT) and 0.94Bi_0.5Na_0.5TiO₃·0.06BaTiO₃ (BNT–BT) bulk ceramics with extensive 〈100〉 texture were prepared by the reactive-templated grain growth method, using platelike Bi₄Ti₃O₁₂ (BIT) particles as templates for BNT. Calcined compacts were composed of matrix grains with random orientation and 〈100〉-oriented grains transformed from aligned BIT particles, and the texture developed by the growth of oriented grains during sintering. Ceramics with extensive texture were obtained by using the starting mixture containing the maximum concentration of platelike BIT to form the maximum volume fraction of oriented grains.     

Softening phenomenon by remilling of styrene–butadiene copolymer rubber–general-purpose polystyrene resin blend

The softening phenomenon by remilling of uncured blends of various commercia styrene—butadiene copolymer rubber (styrene content, 23.5 to 48 wt-%, styrene block 0 to 18 wt-%) with general-purpose polystyrene resin was mainly studied by examining the blend ratio dependence of hardness and compression modulus (in logarithmic form), with special attention to the state of dispersion of the polymers. It was found that the blend of styrene—butadiene copolymer rubber with general-purpose polystyrene resin forms a microheterogeneous polymer blend system and that the hardness and the compression modulus change in S-shaped curves versus blend ratio. However, the degree of softening phenomenon by remilling (roll surface temperature, 70°–90°C) was found to be different for the two blend systems, i.e., random styrene—butadiene copolymer rubber and block styrene—butadiene copolymer rubber. The softening phenomenon is more pronounced in random-type rubbers; and in some block-type rubbers, no softening phenomenon was observed. The influence of the styrene content of the polymer is small. Further discussions have shown us that the strong interaction between the polystyrene block of the copolymer and the styrene homopolymer of the general-purpose polystyrene resin controls the state of dispersion of polymers thereby causing this difference in the softening phenomena among the different kinds of styrene—butadiene copolymer rubbers.     

Probability of precision micro-machining of insulating Si3N4 ceramics by EDM

Electrical discharge machining (EDM) is used as a precision machining method for the electrically conductive hard materials with a soft electrode material. But recently we succeeded to machine on insulating material by EDM. The technology is named as an assisting electrode method. The EDMed surface is covered with the electrical conductive layer during discharge. The layer holds the electrical conductivity during discharge. For micro-EDM, the wear of tool electrode becomes lager ratio than the normal machining. So the micro-machining is extremely difficult to get the precision sample.

In this paper to obtain a fine and precise ceramics sample, some trials were carried out considering the EDM conditions, tool electrodes material and assisting electrode materials. Insulating Si₃N₄ ceramics were used for workpiece. The machining properties were estimated by the removal rate and tool wear ratio. To confirm the change of micro-machining process, the discharge waveforms were observed. The micro-machining of the Ø0.05 mm hole could be machined with the commercial sinking electrical discharge machine.     

Stick-slip motion control based on cutter location data for an orthogonal-type robot

In this article, a new desktop orthogonal-type robot, which has the capacity of stick-slip motion control based on cutter location data, is presented for lapping small metallic molds with a curved surface. The robot consists of three single-axis devices with a high position resolution of 1 μm. A thin wooden stick tool with a ball-end shape is attached to the tip of the z-axis. In order to improve the lapping performance, a novel stick-slip motion control method is developed in the control system. The small stick-slip motion is orthogonally generated in the direction of the tool’s movement. The effectiveness of stick-slip motion control is examined through an actual lapping test of an LED lens cavity.     

Codevelopmental learning between human and humanoid robot using a dynamic neural-network model.

This paper examines characteristics of interactive learning between human tutors and a robot having a dynamic neural-network model, which is inspired by human parietal cortex functions. A humanoid robot, with a recurrent neural network that has a hierarchical structure, learns to manipulate objects. Robots learn tasks in repeated self-trials with the assistance of human interaction, which provides physical guidance until the tasks are mastered and learning is consolidated within the neural networks. Experimental results and the analyses showed the following: 1) codevelopmental shaping of task behaviors stems from interactions between the robot and a tutor; 2) dynamic structures for articulating and sequencing of behavior primitives are self-organized in the hierarchically organized network; and 3) such structures can afford both generalization and context dependency in generating skilled behaviors.     

Imitating others by composition of primitive actions: A neuro-dynamic model

This paper introduces a novel neuro-dynamical model that accounts for possible mechanisms of action imitation and learning. It is considered that imitation learning requires at least two classes of generalization. One is generalization over sensory–motor trajectory variances, and the other class is on cognitive level which concerns on more qualitative understanding of compositional actions by own and others which do not necessarily depend on exact trajectories. This paper describes a possible model dealing with these classes of generalization by focusing on the problem of action compositionality. The model was evaluated in the experiments using a small humanoid robot. The robot was trained with a set of different actions concerning object manipulations which can be decomposed into sequences of action primitives. Then the robot was asked to imitate a novel compositional action demonstrated by a human subject which are composed from prior-learned action primitives. The results showed that the novel action can be successfully imitated by decomposing and composing it with the primitives by means of organizing unified intentional representation hosted by mirror neurons even though the trajectory-level appearance is different between the ones of observed and those of self-generated.