Consistency Management Strategies for Data Replication in Mobile Ad Hoc Networks

In a mobile ad hoc network, data replication drastically improves data availability. However, since mobile hosts' mobility causes frequent network partitioning, consistency management of data operations on replicas becomes a crucial issue. In such an environment, the global consistency of data operations on replicas is not desirable by many applications. Thus, new consistency maintenance based on local conditions such as location and time need to be investigated. This paper attempts to classify different consistency levels according to requirements from applications and provides protocols to realize them. We report simulation results to investigate the characteristics of these consistency protocols in a mobile ad hoc network.     

Lactobacillus reuteri in bovine milk fermented decreases the oral carriage of mutans streptococci

The effect of Lactobacillus reuteri against one of the major cariogenic organism, Streptococcus mutans, was studied. Yogurt products containing L.reuteri showed a significant growth inhibitory effect against S. mutans, whilst yoghurts with lactobaccilli other than L. reuteri did not show such inhibition. Further, double-blind, placebo-controlled trial demonstrated that consuming yogurt with L. reuteri significantly reduced the oral carriage of mutans streptococci, compared with the placebo yogurt.     

Tunability of a 946-nm Nd:YAG microchip laser by use of a double-cavity configuration

We observed the tunability of a 946-nm Nd:YAG microchip laser by using a double-cavity configuration. We shifted the lasers wavelength from 938 to 946 nm by changing the thickness of the air gap. In addition, differences in reflectivity of the output mirror yielded the tunable range of the 946-nm band, with the center oscillation wavelength maintained at 946.1 nm.     

Large area and wide dimensions X-ray lithography using energy variable synchrotron radiation

We developed a new X-ray lithography system for the lithographite, galvanoformung and abformung (LIGA) process using synchrotron radiation at the New SUBARU facility of the University of Hyogo. The X-ray lithography system can utilize two different energy regions: one is a high-energy region: from 2 to 12 keV, and the other is a low-energy region from 1 to 2 keV. Each energy region can be selected in accordance with the size and shape of the desired microstructures. Large-area patterning across an A4-size area was successfully performed with a highly uniform pattern thickness. Furthermore, high-aspect-ratio patterning using a high-X-ray-energy region was also achieved using this X-ray lithography system.     

Calibration methods of carbon nanotube gas sensor for partial discharge detection in SF/sub 6/

The authors proposed a new type of gas sensor for high sensitive detection of decomposition products generated by partial discharge (PD) in SF/sub 6/ gas. The sensor employed carbon nanotubes (CNTs) as gas sensing transducer and was fabricated by electrokinetic manipulation of CNTs using dielectrophoresis. Due to complicated gas decomposition process of SF/sub 6/ gas, calibration of the CNT gas sensor is an essential and challenging subject in order to realize reliable and stable detection of PD under practical conditions. In this paper, two methods for the CNT gas sensor calibration were proposed and tested. The first method was based on initial conductance dependence of the CNT gas sensor response. The CNT gas sensor response to PD increased almost linearly with the amount of CNT trapped onto the sensor electrode, which could be quantified by the initial conductance of the sensor. However, the calibration accuracy of this method was about 50 % and was not high enough for practical use. The second method employed NO/sub 2/ (nitrogen dioxide) as calibration gas because of the similarity in the CNT sensor response to PD decomposition products and NO2. It was found that the accuracy of the NO/sub 2/ calibration was about 10 % and far better than the first method. Finally, effectiveness of the NO/sub 2/ calibration was demonstrated by a PD monitoring test in which two CNT sensors were simultaneously exposed to SF/sub 6/ decomposition products with identical concentration.     

Novel abrasive-free planarization of 4H-SiC (0001) using catalyst

A new abrasive-free planarization method for silicon carbide (SiC) wafers was proposed using the catalytic nature of platinum (Pt). We named it catalyst-referred etching (CARE). The setup equipped with a polishing pad made of Pt is almost the same as the lapping setup. However, CARE chemically removes SiC with an etching agent activated by a catalyst in contrast to mechanical removal by the lapping process. Hydrofluoric acid which is well known as an etchant of silicon dioxide (SiO₂) that cannot etch SiC, was used as the source of the etching agent to SiC. The processed surfaces were observed by Nomarski differential interference contrast (NDIC) microscopy, atomic force microscopy (AFM), and optical interferometry. Those observations presented a marked reduction in surface roughness. Moreover, low-energy electron diffraction (LEED) images showed that a crystallographically well-ordered surface was realized.     

Observation of Antiferromagnetic Spin-Flop Transition in λ-type BETS Salts Using AFM Microcantilever

Antiferromagnetic spin-flop transitions in a series of λ- (BETS)₂FeBr _x Cl_4-x are observed using piezoresistive AFM microcantilever. The measurements are carried out on a tiny single crystal using a sample rotator and the easy axis changes with increasing the bromine content x. The Néel temperature and spin-flop transition field also rise with increasing the bromine content x, suggesting an enhancement of π-d interactions by replacement of chlorine with bromine atoms in this mixed-halide anion system.     

Particle-triggered pre-breakdown phenomena in atmospheric air gap under AC voltage

Corona discharge mechanism and breakdown voltage characteristics of air gaps in the presence of metallic particles were investigated including the relationship between the corona discharge mechanism and the phase resolved partial discharge patterns. These results are of interest for detection of foreign particles in gas insulated systems (GIS). The results with different shaped particles show that the corona mechanism depends on the particle shape and applied voltage. Moreover the corona discharges on both sides of the particle interfere with each other by inflow of charge carriers into the particle. The breakdown voltage is a minimum when the particle is in the vicinity of the electrode due to active interference of coronas. The phase-charge characteristics as the phase resolved partial discharge patterns vary with the particle shape. This suggests that the corona discharge mechanisms for all types of particles should be considered in the particle-detection method for GIS based on the phase resolved partial discharge patterns.     

Influence of hydrogen bonding on the viscosity of coal liquids

Viscosity, infrared, and proton magnetic resonance studies are reported on the SRC II process solvent (before fractionation), and its acid + neutral fraction, and on the interaction of these coal liquids with quinoline and triethylamine. The results obtained with the coal liquids and with several model compounds suggest that hydrogen bonding involving largely phenolic OH and nitrogen-containing bases, OH…N, gives rise to protontransfer complexes, O^?…^pHN, which is in part responsible for the viscosity and non-Newtonian flow of the coal liquids.