Excimer Laser Etching Process of CdTe Crystals for Formation of Deep Vertical Trenches

Deep isolation trenches with high aspect ratio were formed on CdTe crystals using the excimer laser etching technique. Vertical trenches 80-μm deep and 55-μm wide were formed in 5 min by irradiating a laser on the CdTe crystal through a contact-type metal mask in vacuum. Surface chemistry of the laser-irradiated CdTe crystal was examined by Auger electron spectroscopy (AES), scanning electron microscopy (SEM), and photoluminescence (PL) to determine the extent of laser-induced damage. It was found that the damaged layer remains confined to the thin surface layer in the submicron range, which could be easily removed by a light Br-methanol etch.     

DEFORMATION AND FRACTURE OF TiAl PST CRYSTALS UNDER MONOTONIC AND CYCLIC LOADING

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A porous material prepared from the layer-type complex consisting of montmorillonite and α-naphthylamine

Aqueous mixtures of montmorillonite and -naphthylamine with various mixing ratios were kept at 353 K for 3 days with stirring to convert them into the layer-type complex (MNC) consisting of both components, and then dried at 403 K. The resulting blocks, several centimetres in size, were heated below 1473 K under nitrogen. The addition of -naphthylamine (NA) in the equivalent amount to the cation exchange capacity of montmorillonite resulted in the most attractive porous material which includes homogeneous pores of 35nm radius and exhibits a maximum pore volume of 0.8 ml g^–1 at 873 K. The samples containing greater and lesser amounts of NA gave a very brittle block and a less porous block after heating to high temperature, respectively. The materials obtained were also characterized by the waved card-house structure. The amount of NA added and the heat-treatment temperature did not vary the pore size so widely.     

Replicating receptive fields of simple and complex cells in primary visual cortex in a neuronal network model with temporal and population sparseness and reliability

We propose a new principle for replicating receptive field properties of neurons in the primary visual cortex. We derive a learning rule for a feedforward network, which maintains a low firing rate for the output neurons (resulting in temporal sparseness) and allows only a small subset of the neurons in the network to fire at any given time (resulting in population sparseness). Our learning rule also sets the firing rates of the output neurons at each time step to near-maximum or near-minimum levels, resulting in neuronal reliability. The learning rule is simple enough to be written in spatially and temporally local forms. After the learning stage is performed using input image patches of natural scenes, output neurons in the model network are found to exhibit simple-cell-like receptive field properties. When the output of these simple-cell-like neurons are input to another model layer using the same learning rule, the second-layer output neurons after learning become less sensitive to the phase of gratings than the simple-cell-like input neurons. In particular, some of the second-layer output neurons become completely phase invariant, owing to the convergence of the connections from first-layer neurons with similar orientation selectivity to second-layer neurons in the model network. We examine the parameter dependencies of the receptive field properties of the model neurons after learning and discuss their biological implications. We also show that the localized learning rule is consistent with experimental results concerning neuronal plasticity and can replicate the receptive fields of simple and complex cells.     

Gyro-based odometry associated with steering characteristics for wheeled mobile robot in rough terrain

Mobile robot used for planetary exploration performs several scientific missions over long distance travel and needs to have a high degree of autonomous mobility system because the communication delay from the Earth impedes its direct teleoperation. Localization of a mobile robot is of particular importance on the autonomous mobility. Classical localization methods such as wheel/visual odometry have been widely investigated and demonstrated, but they possess a well-known trade-off between computational cost and localization accuracy. This paper proposes an accurate gyro-based odometry method for a wheeled mobile robot in rough terrain. The robot in rough terrain is often subject to large wheel slip or vehicle sideslip related with its steering maneuver, and those slips degrade the localization accuracy. The basic approach of the proposed method is to exploit odometry data for the robot distance traveled as well as gyroscope data for the robot heading calculation; however each data-set is weighted in accordance with steering characteristics of a robot in rough terrain. The usefulness of the proposed method is examined through field experiments using a wheeled mobile robot testbed in Martian analog site. The experimental result confirms that the proposed method accurately estimates the robot trajectory.     

MRT letter: Expression of ATP sensor protein in Caenorhabditis elegans

Adenosine 5'-triphosphate (ATP) is the major energy currency and is involved in many biological processes. The ATP-monitoring system for cells in animals can be helpful to study the relationship between energy metabolism and biological processes. The fluorescent ATP biosensor ATeam (ATP indicator based on Epsilon subunit for Analytical Measurements), which has been reported to monitor ATP levels in cultured cells on the basis of fluorescence resonance energy transfer (FRET), was introduced into nematodes by microinjection and UV-irradiation method. To confirm whether ATeam functions as an ATP sensor in nematode cells, the authors measured FRET of ATeam in cells of transgenic nematode. The ATeam was expressed in target cells in nematode. In vulva cells, ATP levels in the cytosol were higher than those in mitochondria. ATeam also sensed ATP level change in cultured cells from the transgenic nematode. These experiments indicated that ATeam is available for detection of changes in ATP levels in nematode cells.     

The first isolation of Arthroderma benhamiae in Japan

BACKGROUND: Hepatitis C virus (HCV) infection induces variable dermatologic manifestations. Our purpose was to determine whether there is an association between HCV infection and oral lichen planus (OLP). METHODS: Antibodies to HCV were determined in patients with OLP (263 patients; 156 women and 107 men, with a mean age of 55.5 years) and in a control population. RESULTS: Seventy six cases (28.8%) were positive for HCV antibodies with the second-generation enzyme-linked immunosorbent assay (ELISA II) test. All of these cases were confirmed with the second-generation recombinant immunoblot assay (RIBA II) test. In 61 cases (23.1%), high levels of serum transaminase were found. Positivity for hepatitis B virus (HBV) markers was found in 31 patients (11.7%) and for hepatitis A virus (HAV) markers in 43 patients (16.3%). None had positivity for hepatitis D virus (HDV) markers. As a control group, we used 100 patients (58 women and 42 men, with a mean age of 55.3 years) referred to the School of Dentistry of the University of Naples "Federico II," and treated for general dental caries. In the control group, HCV antibody positivity was found in three cases. CONCLUSIONS: The high prevalence of HCV antibody in this group of patients with OLP, higher than in the healthy population, suggests a link (p = 1.423 x 10(-7), chi-squared test) between these two diseases. These findings stress the importance of liver examination in OLP patients, and the need for other studies on the high susceptibility to hepatitis viruses in the population in the southern part of Europe.     

Principle of surface charge measurement for thick insulatingspecimens

We discuss the method for measuring surface charge density accumulated on the surface of a solid dielectric (insulating specimen) such as a supporting spacer in gas and vacuum insulated equipment. For such thick specimens, the probe response does not correspond to the charge density directly below the probe, so the measurement necessitates multipoint data together with the aid of numerical field calculations. The probe gives either induced charge or floating potential in response to the surface charge. We compare various previously proposed techniques and give a reasonable procedure for analyzing the data     

Weak approximation of transformed stochastic gradient MCMC

Stochastic gradient Langevin dynamics (SGLD) is a computationally efficient sampler for Bayesian posterior inference given a large scale dataset and a complex model. Although SGLD is designed for unbounded random variables, practical models often incorporate variables within a bounded domain, such as non-negative or a finite interval. The use of variable transformation is a typical way to handle such a bounded variable. This paper reveals that several mapping approaches commonly used in the literature produce erroneous samples from theoretical and empirical perspectives. We show that the change of random variable in discretization using an invertible Lipschitz mapping function overcomes the pitfall as well as attains the weak convergence, while the other methods are numerically unstable or cannot be justified theoretically. Experiments demonstrate its efficacy for widely-used models with bounded latent variables, including Bayesian non-negative matrix factorization and binary neural networks.