Formation of a mental abacus for computation and its use as a memory device for digits: A developmental study.

In order to examine whether representational changes in digit memory would be observed as a function of the extent of expertise in mental-abacus operation, five groups of operators, differing in extent of expertise (i.e., novices, lower intermediates, intermediates, junior experts, and experts), were required (a) to reproduce series of five digits either forward or backward as quickly as possible and (b) to perform a simple aural-verbal or visual-spatial task interpolated between the presentation and reproduction of a near-span series of digits. The intermediates and more skilled operators as well as a majority of the lower intermediates showed nearly equal amounts of time for forward and backward reproduction, whereas novices took a much longer time for backward than for forward reproduction. The more skilled operators were, the less vulnerable was their memory for digits to the aural-verbal interpolated task (a relation that was significant) and the more vulnerable to the visual-spatial task (a relation that was insignificant). These results strongly suggest that the advanced operators applied their mental abacus to digit memory. It is claimed that a system of representation formed through routine problem solving is transferred automatically to other cognitive tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Antiproliferative constituents in umbelliferae plants. III. Constituents in the root and the ground part of Anthriscus sylvestris Hoffm

To test whether mitogen-activated protein kinases (MAPKs) are involved in microglial activation, pure microglia prepared from 1- to 3-day-old rat brains were activated with either 100 ng/ml lipopolysaccharide (LPS) or 5 nM synthetic beta-amyloid (Abeta) (25-35). The patterns of MAPK activation following LPS and Abeta treatment were very similar. Three MAPK subtypes, p38, extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) were activated within 15 min and the activities of p38 and ERK were rapidly reduced to background level within 30 min while that of JNK was maintained for over 1 h. Both inhibitors of p38 (SB203580) and ERK pathway (PD098059) reduced LPS-induced nitric oxide (NO) release and Abeta-induced tumor necrosis factor-alpha (TNF-alpha) release. Furthermore, co-treatment of SB203580 and PD098059 additively reduced NO and TNF-alpha release. These results suggest that MAPK, at least p38 and ERK, mediate LPS-, and Abeta-induced microglial activation.     

Effect ofd-α-tocopherol analogues on lipoxygenase-dependent peroxidation of phospholipid-bile salt micelles

In order to know whether or not vitamin E acts as an effective antioxidant in lipoxygenase-dependent peroxidation of phospholipids, the effect of vitamin E and vitamin E analogues, 2,2,5,7,8-pentamethyl-6-hydrohychroman (PMC) and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox C), was investigated in enzymatic lipid peroxidation of bile salt micelles of pig liver phosphatidylcholine (PC) using soybean lipoxygenase. 15-Hydroperoxy-5,8,11,13-eicosatetraenoic acid was exlusively produced by the reaction with the PC molecular species containing arachidonic acid moiety, indicating that the hydroperoxidation of pig liver PC entirely progresses through the enzymatic reaction. PMC suppressed the accumulation of PC-hydroperoxides (PC-OOH) more efficiently than eitherd-α-tocopherol (α-Toc) or Trolox C, and 50% inhibition concentration by PMC was close to that of quercetin, a known lipoxygenase inhibitor from natural origin. The antioxidant activity of PMC was also superior to that of either α-Toc or Trolox C in ferrous ion-induced nonenzymatic oxidation of PC micelles in the presence of a trace amount of PC-OOH, although the radical-scavenging activities of these compounds in solution were similar or comparable to one another. In conclusion, PMC is more effective than α-Toc as an inhibitor of lipoxygenase reaction with phospholipids and of autoxidation in phospholipids. The phytyl chain of α-Toc seems to be unfavorable for exerting an inhibitory effect on lipoxygenase reaction with phospholipid-bile salt micelles.     

Tuberculin sensitivity to purified protein derivatives from Mycobacterium other than tuberculosis (PPD-B, PPD-Y, PPD-F and PPD-C) and PPDs among patients with mycobacteriosis--cooperative study of the Research Committee for the Mycobacteriosis in Japan

Purified protein derivatives (PPDs) prepared from M. intracellulare (PPD-B), M. kansasii (PPD-Y), M. fortuitum (PPD-F), M. chelonei subsp. abscessus (PPD-C) and M. tuberculosis (PPDs) were simultaneously used in skin tests on patients diagnosed as having tuberculosis or atypical mycobacteriosis to reveal their specificity, clinical usefulness and immunological status of the patients. The mean diameter of reaction (redness) for patients with M. tuberculosis positive sputum (TB group, n = 71; age, 20-90 yrs) was PPDs, 20.4 mm; PPD-B, 7.9 mm; PPD-Y, 11.7 mm; PPD-F, 0.8 mm; and PPD-C, 0.3 mm. For M. avium complex positive patients (MAC group, n = 100; age, 31-89 yrs), the results were PPDs, 10.9; PPD-B, 16.9 mm; PPD-Y, 10.7 mm; PPD-F, 1.6 mm; and PPD-C, 0.3 mm. The M. kansasii positive patients (K group; n = 8) showed results of PPDs, 12.6 mm; PPD-B, 10.7 mm; PPD-Y, 20.8 mm; PPD-F, 0.5 mm; PPD-C, 0.0 mm. The M. fortuitum positive patients (F group; n = 5) had measurements of PPDs, 5.8 mm; PPD-B, 4.4 mm; PPD-Y, 9.8 mm; PPD-F, 17.8 mm; and PPD-C, 16.0 mm. The patients who were previously M. tbc. positive but presently negative patients (pre. TB group; n = 50) showed the following results: PPDs, 16.6 mm; PPD-B, 7.4 mm; and PPD-Y, 10.9 mm. For the patients who were previously M. avium complex positive (previous MAC group; n = 19), the results were PPDs, 10.4 mm; PPD-B, 9.9 mm; and PPD-Y, 7.7 mm. Also considering their frequency distribution curve, with exception of the previous MAC group, the patient groups showed specificity to the PPD of the bacilli detected. The previous MAC group recorded no significant difference in response to PPDs and PPD-B. Strong cross reactions were observed between PPD-F and PPD-C, and moderate reactions between PPDs, PPD-B and PPD-Y. Cross reactions were scarce between PPDs, PPD-B or PPD-Y and PPD-F or PPD-C. Though it is difficult to distinguish cross-reaction and multiple infections, majority of the patients (72-85%) showed greatest response to the PPD that corresponds with the species of bacilli detected. In conclusion, two or more PPDs applied simultaneously can be of aid in diagnosing mycobacteriosis especially in the early stages of the disease. Also, cross-reactions between atypical mycobacteria and PPDs should be taken into consideration when diagnosing infection caused by M. tuberculosis.     

Space charge formation and breakdown in polyethylene influenced by the interface with semiconducting electrodes

This paper deals with the influence of interface between polyethylene and semiconducting electrode on the space charge formation and electrical breakdown. Low‐density polyethylene (LDPE) films attached with different semiconducting electrodes were subjected to the DC breakdown test, and corresponding space charge distribution was measured. A heat treatment to LDPE itself did not bring about a significant change in space charge profile; however, when a semiconducting electrode was hot‐pressed, the impurities would migrate into LDPE at high temperature, leading to the change in space charge profile. Furthermore, it was suggested from the comparison between the results with degassed and as‐received semiconducting electrodes that some carriers relating to impurities in the electrode would move into LDPE under the voltage. In addition, it was shown that the breakdown is not determined by the field at the cathode which can supply sufficient electrons, but by the maximum field across the specimen, suggesting that an increase in conduction current due to the generation and/or injection, rather than the electronic avalanche process, leads to the breakdown. © 2001 Scripta Technica, Electr Eng Jpn, 138(3): 19–25, 2002     

High-field conduction and breakdown in insulating polymers. Presentsituation and future prospects

We review the results of electrical conduction and breakdown research reported mainly after 1980 in Japan, and comment on the present situation and future prospect of research work in this field. Effects of introduction of polar groups into polymers on electric strength F_b are summarized. Influences of copolymerization and modification of morphology and chemical structure on F_b of polyethylene are also reviewed. Finally, we show currently used experimental techniques for direct observation of space charge, prebreakdown current and localized heat generation     

Layer Generation Process on Work-piece in Electrical Discharge Machining

In recant years, surface modification of metals and machining of insulating ceramics by electrical discharge machining (EDM) have been successfully carried out. In surface modification by EDM with semi-sintered electrodes, worn substances in the gap region form the material source of the layer generated on the work-piece surface. In the machining of insulating ceramics by EDM, a crystallized carbon layer or carbide layer from the working oil covers the surface of the insulator. Increase in the thickness of the generated layer, however, tends to stop at a certain maximum value in both surface modification by EDM with semi-sintered electrodes and machining of insulating ceramics by EDM processes. In these machining operations, accretion and removal phenomena occur alternately. In this paper, the mechanisms of machining insulators and the accretion process are discussed considering the characteristics of the generated layers on the work-piece surface.     

Scanning electron microscopy and energy-dispersive X-ray analysis of self-etching adhesive systems to ground and unground enamel

The morphological analysis of the ground and unground enamel was treated with three different self-etching adhesive systems. Ultrastructural features were observed by using the field emission scanning electron microscope (FESEM) in combination with Energy Dispersive X-Ray Spectroscopy (EDS) analysis. Thirty extracted human molars were used for this study. Teeth were divided into two groups. In the first group unground enamel was etched with either Clearfil SE Bond (Kuraray-Japan), G Bond (GC-Japan) or Tri S Bond (Kuraray-Japan) according to the manufactures instructions. In the second group ground enamel was treated as above. In addition 24 ungrounded and grounded enamel specimens were etched and bonded with the three self-etching adhesives and restored with composite resin (Clearfil ST-Kuraray). Then they were cross-sectioned and interfacial analysis was done with the combination of EDS analysis. Etching patterns of the enamel varied according to the self-etching adhesive. Clearfil SE Bond produced micro-irregular etching pattern creating crater like area in ground enamel while other two produced mild etching pattern. All three adhesives produced incomplete etching on unground enamel. Interfacial studies showed demineralization for the bonding agent penetration and the formation of hybrid layer. The self-etching adhesives produced different specific SEM morphologies on unground and ground enamel.