Thermal link for cartridge-type cryostat

We have developed a simple and small thermal link for cooling a cylindrical cartridge, on which device under test is mounted. It consists of a crown-like ring with an inner diameter of 170 or 140 mm and a clamping belt, which is a metal spring or nylon. A thermal conduction of the thermal link is achieved as the crown-like ring clamps the disk-like stage of the cartridge with external force of the clamping belt. This link can be applied at various temperature ranges from 2 to 100 K. The measured thermal conductance of the 170 mm link is 1.7, 5.6 and 3.3 W K⁻¹ for 4, 12, and 80 K stages, respectively. These values are consistent with a empirical calculation within 10% errors. This link is also effective to reduce mechanical vibration to be 6 μm (peak-to-peak) in the horizontal direction of the cartridge. This link is easily fabricated and is useful to various detectors which require to be cooled down.     

Ultrawide-band La-codoped Bi/sub 2/O/sub 3/-based EDFA for L-band DWDM systems

The demonstration of a 253-cm-long lanthanum-codoped Bi/sub 2/O/sub 3/-based erbium-doped fiber which provides gain of greater than 20 dB and noise figure less than 6.7 dB to 142 dense wavelength-division-multiplexing channels simultaneously over an extended wavelength range of 58 nm from 1554 to 1612 nm is reported. The 3-dB (gain of 17-20 dB) bandwidth of the erbium-doped fiber amplifier is 54 nm when it is pumped with 350 mW of 1480-nm light. The power conversion efficiency of the fiber is about 54%.     

An advanced defect-monitoring test structure for electrical screening and defect localization

A new test structure for the detection and localization of short and open defects in large-scale integrated intralayer wiring processes is proposed. In the structure, an open-monitoring element in the first metal layer meanders around lines of short-monitoring elements placed in contact with N-type diffusion regions to make the structure compact. The proposed structure allows defective test structures to be screened through electrical measurements and killer defects to be localized through voltage contrast or optical microscopy methods.     

Novel properties of new type conducting and insulating polymers andtheir composites

Novel properties of recently developed conducting and insulating polymers and their composites are discussed. Properties of conducting polymer whose main chains are composed of unsaturated π-bonds depend strongly on the main chain structure, substituent and also molecular dopants. Various applications of conducting polymers such as electroluminescence (EL) elements, electrolyte capacitors, photoconductors, photovoltaic cells, superconductors and insulators at cryogenic temperature, are discussed by taking effects of molecular dopants such as C₆₀ into consideration. A new type of insulating polymer, syndiotactic polypropylene prepared by newly developed metallocene catalysts has been studied and found to exhibit much superior electrical, thermal and mechanical characteristics compared with those of conventional isotactic polypropylene, atactic polypropylene and polyethylene. These excellent characteristics originate from lower crystallinity, smaller spherulites and different crystal lattice than in isotactic polypropylene. Negligible degradation of syndiotactic polypropylene by contact with copper is interpreted in terms of difference of catalysts and suppression of diffusion of copper cation. New types of conducting polymer, insulating polymer composites were prepared. Their conductivity was controlled over more than 10 orders of magnitude by small amounts of a conducting polymer, polypyrrole, which can be interpreted in terms of the percolation model depending on the shape and density of polypyrrole coated insulating polymer particles. Nonlinear current-voltage characteristics were also studied     

Determination of power reflectivity of quasi-graded distributedBragg reflectors using stopband width

The authors examine the reflectivity of the quasi-graded distributed Bragg reflector using the stopband width. The stopband width of about 1000 Å for a reflectivity of about 99% is able to be measured with an accuracy of ± 1 Å. Thus, the reflectivity is determined with high accuracy from the stopband width. It is found that the quasi-graded distributed Bragg reflector is a high-quality reflector with high reflectivity and low resistance     

Influence of charged droplet cloud on flashover of air gaps for lightning impulse voltage

Transmission lines passing through a mountainous region often are struck by winter lightning. As a result, numerous double-circuit faults occur. Space charge might be responsible for this phenomena. Several investigations on flashover characteristics have been performed focusing on reduction of flashover voltage due to ionic space charge formed by corona discharge. In this paper, flashover characteristics of an air gap within a charged droplet cloud ejected from an airless nozzle using an induction charging method are discussed. The droplets are charged in the range -200 to 200 μC/kg, forming the space-charge density of approximately 13 μC/m³. The flashover voltage and the time lag to flashover were measured when 1.2 × 50 μs lightning impulse voltage applied to a rod-sphere gap is placed within the charged cloud. Flashover voltage for a positive rod increased markedly within a positive charged cloud by increasing the charge-to-mass ratio. The increase of flashover voltage was up to 80 percent in comparison with uncharged droplets. Flashover voltage for the negative rod decreased about 20 percent in the cloud of either polarity. The results show that the presence of charged droplets in the air gaps affects the discharge process significantly.     

Increased expression of endothelial cell nitric oxide synthase (ecNOS) in afferent and glomerular endothelial cells is involved in glomerular hyperfiltration of diabetic nephropathy

Root coverage procedures have become an important part of periodontal therapy. The purpose of this study was to compare 2 techniques, 1) guided tissue regeneration (GTR) with a bioabsorbable polylactic acid softened with citric acid ester membrane and 2) the connective tissue graft combined with a coronally positioned pedicle graft without vertical incisions. The GTR procedure produced a mean root coverage of 92.3% and the connective tissue graft combined with a coronally positioned pedicle graft, 95.0%. This difference was not statistically significant. Both procedures produced similar reductions in recession depth, recession width, and probing depth. The connective tissue graft combined with a coronally positioned pedicle graft resulted in a greater increase in the amount of keratinized tissue. Based on this study, both procedures can result in statistically similar amounts of mean root coverage, but the results are not identical. In most cases, the connective tissue with coronally positioned pedicle graft produced a more bulky result than guided tissue regeneration. Therefore, the procedures are not interchangeable.     

Sequence analysis of functional regions of homoserine dehydrogenase genes from L-lysine and L-threonine-producing mutants of Brevibacterium lactofermentum

The homoserine dehydrogenase (HD) genes from Brevibacterium lactofermentum lysine- and threonine-producing mutants were cloned, using the polymerase chain reaction, and sequenced. We found the amino acid substitutions, Val104Ile in the lysine-producing mutants in which HD may cause leaky mutation and Ser393Phe in the threonine-producing mutant with feedback-insensitive HD.     

A case of porencephaly with mirror movements: pathophysiological investigation by using long-latency long-loop reflex and dipole tracing method

We report a 42-year-old left-handed woman with congenital right hemiparesis and bilateral mirror movements in the hands. She had a porencephaly of the left hemisphere and the brain MRI demonstrated cortical and subcortical defect of the left hemisphere from Brodmann's area 6 to 40 including the left motor cortex. By electrical stimulation of the left median nerve at the wrist, N20 of the somatosensory evoked potential was recorded in the right postcentral gyrus by using the dipole tracing method. Long-loop reflexes from the bilateral thenar muscles were recorded and their latencies were almost the same. The stimulation of the right median nerve did not evoke N20, nor long-loop reflex. These electrophysiological findings suggest that the reorganization of the motor system made the right motor cortex to innervate bilateral hands, and caused bilateral mirror movements. In other words, the mirror movements managed to relieve the paralysis of the right hand though the damage of the left motor cortex was present. In the previous literature we are able to find hypotheses regarding the mechanism of mirror movements in congenital hemiparesis. Here we discussed about the reorganization of the motor system in the damaged brain.