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.     

Development of an automatic Vickers hardness testing system usingimage processing technology

The mechanical characteristics of machines or machine parts depend on the properties of the materials from which they are made. Hardness is an especially important index for machine design. The Vickers hardness number of a test material is defined by the surface area of the indentation made in the surface of a test specimen by a diamond pyramid indenter. Diagonal lines that indicate the indentation size are usually several micrometers to several hundred micrometers long, depending on the hardness of the material. Conventional automatic Vickers hardness testing systems have been applied only to specular-polished specimens. A new fully automatic Vickers hardness testing system has been developed that emulates visual Vickers hardness testing in terms of accuracy and that automatically sets the threshold level of the image processor to suit indentation image data. It can be applied not only to the testing of rough-polished specimens while meeting the measurement accuracy specified in Japanese Industrial Standard (JIS) B 7725, but can also process one indentation within 20 s, including the indenting, focusing and image processing time     

Resonance phenomena of a single water droplet located on a hydrophobic sheet under AC electric field

Resonance vibration of a water droplet located on the surface of a hydrophobic sheet under an AC electric field was investigated experimentally. In order to confirm the effect of the surface property of hydrophobic materials on the resonance phenomena of a water droplet, three kinds of hydrophobic materials, silicone rubber (SR), polytetrafluoroethylene (PTFE), and polydimethylsiloxane-grafted fluoropolymer (PGF) sheet were used. A single water droplet with a volume ranging from 3 to 30 /spl mu/L was placed between parallel electrodes, where a tangential electric field was formed along the surface of the hydrophobic sheet. A water droplet under the AC field vibrates strongly only at a particular frequency range. The resonance frequency, when the water droplet vibrates, decreases with increasing the volume of the water droplet. The resonance frequency on the SR sheet is lower than that on the PTFE and the PGF sheet. The resonance frequency and the magnitude of the deformation of the water droplet depend on the surface properties of the hydrophobic material.     

Group velocity dependence of propagation losses in single-line-defect photonic crystal waveguides on GaAs membranes

Group velocity, v/sub g/, dependence of propagation loss in single-line-defect photonic crystal waveguides on GaAs membranes, and minimum loss as low as 2.5 dB/mm, are presented. When v/sub g/ is reduced by a factor of 7, an additional loss is found to be only 5 dB/mm, thus proving a feasible usage of low v/sub g/.     

Endothelin-induced activation of mitogen-activated protein kinases in glomerular mesangial cells from normotensive and stroke-prone spontaneously hypertensive rats

1. Kinase assay in myelin basic protein (MBP) containing polyacrylamide gels revealed that endothelin-1 (ET-1) and ET-3 increased MBP kinase activities in glomerular mesangial cells (MC) from Wistar-Kyoto (WKY) rats and spontaneously hypertensive rat (SHRSP). ET-1 stimulated MBP kinase activities more potently than ET-3. 2. Immunoprecipitation with anti-41-kDa MAPK antiserum showed that the MBP kinases activated by ET-1 correspond to 43- and 41-kDa MAPK. 3. Since Phorbol 12-myristate 13-acetate, a direct activator of protein kinase C, also activated MAPK, protein kinase C was suggested to mediate ET-induced activation of MAPK. 4. These results suggest that MAPK may mediate the ET actions in glomerular mesangial cells from normotensive rats as well as spontaneously hypertensive rats. Since ET is produced by vascular endothelial cells of the kidney and glomerular mesangial cells, the ET signalling pathway may have some physiological and pathophysiological significance in vivo glomerulus.     

Expression of multidrug resistance-associated protein (MRP) in head and neck squamous cell carcinoma

Vascular parkinsonism is thought to be a distinct parkinsonian syndrome associated with small deep infarcts and white matter lesions (WMLs). We studied the prevalence of parkinsonian features (bradykinesia, rigidity, tremor, and gait disorder) in relation to small deep or territorial infarcts and WMLs on computed tomography (CT) in 62 lacunar and 41 territorial stroke patients, at 3.0 (median) years of follow up. One or more parkinsonian signs were found in 36% of these patients; 11% clinically had parkinsonism. Parkinsonian signs were found more frequently in lacunar than in territorial stroke patients: bradykinesia in 45% and 7%, rigidity in 13% and 7%, tremor in 6% and 7%, and gait disorder in 16% and 7%, respectively. Patients with WMLs at study entry (n = 16) were compared with those without WMLs (n = 87): 56% and 25% had bradykinesia, 25% and 8% rigidity, 25% and 3% tremor, and 38% and 8% gait disorder, respectively. Regression analysis with adjusted odds ratios ([a]OR) showed that WMLs at study entry were associated with bradykinesia ([a]OR 8.0, 95% confidence interval [CI] 1.6-41.6), gait disorder ([a]OR 7.1, 95% CI 1.5-33.7), and tremor ([a]OR 7.0, 95% CI 1.2-40.3). Bradykinesia was associated with lacunar stroke at study entry ([a]OR 11.5, 95% CI 2.4-54.9). Thus, one third of our stroke patients had one or more parkinsonian signs, and 10% clinically had a parkinsonian syndrome that differed from Lewy body parkinsonism: infrequent resting tremor, but frequent gait disorder. Parkinsonian signs were associated with WMLs and lacunar stroke. Therefore, this study favors a distinct vascular parkinsonian syndrome.