A 2.5-ns clock access, 250-MHz, 256-Mb SDRAM with synchronousmirror delay

A 256-Mb SDRAM (245.7 mm²) has been developed using (1) a high cell occupation ratio (60.2%) array design for chip size reduction and a high yield, (2) a prefetched pipeline scheme (PPS) using a first-in first-out (FIFO) buffer with parallel serial converter for 250-MHz clock frequency operation, and (3) a synchronous mirror delay (SMD) circuit for 2.5-ns clock access and low standby current     

Deep level transient spectroscopy study of electron-irradiated CuInSe<Subscript>2</Subscript> thin films

Irradiation of high-energy (2-MeV and 3-MeV) electrons on single-crystalline n-CuInSe₂ films has been investigated. From Hall-effect measurements of the film, the carrier density and mobility were decreased by increasing the electron fluence above 1×10¹⁷ cm⁻². In both as-grown and electron-irradiated CuInSe₂ films, the deep level transient spectroscopy (DLTS) peak, indicating electron trap, was found at around 180 K. However, Arrhenius plots of the observed DLTS peaks in as-grown and electron-irradiated films showed different behavior, suggesting the presence of electron traps introduced by high-energy electron irradiation.     

The leech excitatory peptide, a member of the GGNG peptide family: isolation and comparison with the earthworm GGNG peptides

A member of the GGNG peptide family was isolated from Hirudo nipponia (leech). GGNG peptides had only been isolated previously from earthworms. The C-terminus structure of the leech peptide, LEP (leech excitatory peptide), was -Gly-Gly-Asn-amide, while that of the earthworm peptides, EEP (earthworm excitatory peptide), was -Gly-Gly-Asn-Gly. LEP exerted 1000-fold more potent activities on leech gut than did EEP-2. On the other hand, EEP-2 was 1000-fold more potent than LEP on the crop-gizzard of the earthworm. Analog peptides of LEP and EEP-2 were synthesized, and the myoactive potency of each analog on the leech and earthworm tissues was compared.     

Subacute and chronic subarachnoid hemorrhage: diagnosis with fluid-attenuated inversion-recovery MR imaging

SNARE proteins have been implicated in the insulin-induced translocation of vesicles containing the GLUT4 glucose transporter to the plasma membrane of adipocytes. The role of the target SNARE SNAP-25 or its homologs in this process was investigated by screening a mouse adipocyte cDNA library with rat SNAP-25 and human SNAP-23 cDNA probes. Both positive clones isolated encoded a protein with 87% sequence identity to human SNAP-23, and which was therefore designated mouse SNAP-23. Immunoblot and immunofluorescence analyses revealed that SNAP-23 is located predominantly in the plasma membrane of 3T3-L1 adipocytes incubated in the absence or presence of insulin. Of syntaxins 1 to 5, SNAP-23 bound with the highest affinity to syntaxins 1 and 4 in the yeast two-hybrid system. Expression of SNAP-23, syntaxin 4, and the syntaxin-binding protein Munc 18c in COS cells revealed that Munc18c reduced the amount of SNAP-23 bound to syntaxin 4 in a concentration-dependent manner. These results suggest that the binding of SNAP-23 to syntaxin 4 is inhibited by Munc18c in adipocytes.     

Ether extract of fetal calf serum protects cultured rat cortical neurons against glutamate cytotoxicity

OBJECTIVE: To elucidate the role of Helicobacter pylori in relapsing disease after partial gastrectomy for peptic ulcer. DESIGN: Retrospective study of gastroscopies between January 1985 and February 1988. SETTING: Department of Surgery, Helsinki University Central Hospital, Finland. PARTICIPANTS: One hundred and fifty-five patients, who had undergone partial gastrectomy for peptic ulcer disease. MAIN OUTCOME MEASURES: Correlation between clinical and laboratory data, macroscopic findings at gastroscopy and histopathology. RESULTS: At gastroscopy 41 patients showed an ulcer at the site of anastomosis or in the gastric stump and two patients had a history of a previous ulcer recurrence. The median time interval between operation and relapse was 4 years. There was no correlation between ulcer recurrence, sex, age, ABO blood group or other diseases. Smokers and patients using non-steroidal anti-inflammatory drugs (NSAIDs) or alcohol had more relapses, but the difference was not significant. The recurrence rate was higher after Billroth II (BII; 34%) than after Roux-en-Y (14%; P = 0.03) or Billroth I (BI) reconstruction (24%). Giemsa staining demonstrated H. pylori in the gastric stump of 37% of the patients. H. pylori expression was related to age but unrelated to sex, ABO blood group, NSAID use, smoking or alcohol consumption. H. pylori positivity was more common (52%) after BI than after BII (28%; P = 0.04) or Roux-en-Y resection (40%). Recurrent ulcer was more often found in gastric remnants with normal mucosa (36%) than in those with H. pylori-positive gastritis (18%; P = 0.03) or H. pylori-negative gastritis (26%). CONCLUSION: It seems that H. pylori infection plays a minor role in the pathogenesis of ulcer recurrence after partial gastrectomy for peptic ulcer disease. Eradication of H. pylori of the remnant stomach is therefore presumably not effective in preventing ulcer recurrence.     

Second-order distortion of amplified intensity-modulated signalswith chirping in erbium-doped fiber

Second-order distortion produced in an erbium-doped fiber amplifier (EDFA) is investigated theoretically and experimentally. Rate equations for intermodulation products are led by the perturbation method. From numerical calculation, it is shown that optimum combinations of input power to EDFA and signal wavelength exist that give a distortion-free condition, Improvement of the composite second-order (CSO) distortion, which results from the cancellation of the laser distortion and the gain tilt induced distortion, was confirmed for VHF multichannel transmission. Furthermore, CSO distortion-free transmission in cascaded EDFA's has been demonstrated for a 42-channel AM-SCM signal by experimentally determining the optimum operating condition of the EDFA such that each amplifier generates no additive distortion     

A circuit technology for a self-refresh 16 Mb DRAM with less than0.5 μA/MB data-retention current

A 16M self-refresh DRAM achieving less than 0.5 μA per megabyte data retention current has been developed. Several techniques to achieve low retention current, including a relaxed junction biasing (RTB) scheme, a plate-floating leakage-monitoring (PFM) system, and a V_BB pull-down word-line driver (PDWD) are described. An extension of data-retention time by three-fold and the refresh timer period by 30-fold over previously reported self-refresh DRAMs has been achieved. This results in a reduction of the ac refresh-current to less than 0.4 μA per megabyte. Furthermore, the addition of a gate-received V_BB detector (GRD) reduces dc retention current to less than 0.1 μA per megabyte. This allows a 20-megabyte RAM disk to retain data for 2.5 years when powered by a single button-shaped 190-mAh lithium battery     

First isolation of a rickettsia closely related to Japanese spotted fever pathogen from a tick in Japan

In May 1993, we collected unfed ticks in Anan, Tokushima Prefecture, Shikoku District, Japan, a highly endemic area of Japanese spotted fever (JSF). We isolated JSF rickettsiae from these ticks by inoculating tick-emulsions into L-929 cells. Of the four genera and seven species of ticks examined, only one larva of Dermacentor taiwanensis Sugimoto yielded a rickettsial isolate. The isolate (DT-1 strain) was found to belong to the serotype common to the causative agent of JSF. This was based on its specific reactivity to mouse antisera and to a monoclonal antibody to JSF rickettsiae from the Shikoku District. This is the first tick-borne spotted fever group of rickettsia isolated in Japan. However, all stages of D. taiwanensis infrequently parasitize humans. Some ticks in the genus Haemaphysalis commonly infest humans and are frequently found to be rickettsia-positive in the hemolymph test when using the monoclonal antibody mentioned above. Therefore, the vectors of JSF rickettsiae to humans may be a complex of tick species.