Superconductivity in W-containing diamond-like nanocomposite films

Superconductivity in a tungsten-containing carbon-oxide film was reported. The film with 500 nm thickness was deposited onto polycrystalline silicon oxides using chemical vapor deposition and the co-sputtering of a tungsten metal target. The bonding state of the carbon atoms and the macroscopic and microscopic crystal structure of the film were investigated by Raman spectroscopy, X-ray diffraction and transmission electron microscopy measurements. From the experimental results, we determined that this film essentially had an amorphous structure. The temperature dependence on resistivity was measured in the temperature range of 2–300 K. Resistive superconducting transition was observed at 3.8 K. The dc magnetizations were measured in the temperature range of 1.8–6.5 K. The diamagnetism resulting from a superconductive state was observed below 3.75 K, which is consistent with a resistive superconducting transition. It is thought that the finite sized clusters of the different superconductive transition temperatures cooperatively produce a macroscopic superconducting phenomenon.     

An integrated laser blood flowmeter

We have constructed a very small and lightweight blood flowmeter using micromachining and surface mounting techniques for a wearable health monitoring system. The hybrid integrated structure of the optical system incorporates a InGaAsP-InP distributed feedback laser diode (DFB-LD) with a wavelength of 1310 nm, an edge-illuminated photodiode (PD) and a polyimide waveguide on silicon substrate (2 mm /spl times/ 3 mm). This integrated flowmeter can be positioned directly on the tissue and permits real-time monitoring of capillary microcirculation. In-vivo measurements of blood perfusion in a finger confirm the feasibility of the blood flowmeter.     

Analysis of higher information density pregroove model by boundary element method

Using the boundary element method, results of the push-pull ratio of differential output signals from an optical disc pregroove model by simulation are presented. The possibility of achieving higher information density by reducing the track pitch and the beam spot is demonstrated.<>     

Performance analysis of disk allocation method usingerror-correcting codes

The problem of distributing a Cartesian product file on multiple disks to maximize the parallelism for partial match queries is addressed. C. Faloutsos et al. (1989) have proposed an allocation method for Cartesian product files on multiple disks by using linear error-correcting codes. The performance of the allocation method is analyzed. Some conditions under which the allocation method is strictly optimal for queries with a given number of unspecified attributes are presented. A necessary and sufficient condition for a linear code to give a strictly optimal allocation method is discussed. Formulas for the average response time on queries with w unspecified attributes, denoted T_w, in terms of the weight distribution of the code or its dual code, and formulas for the average response time Ton all queries, are given. Several examples whose average response times T_w or T are close to theoretical lower bounds are presented     

Application-aware buffer management: new metrics and techniques

An important issue for video transmission over IP networks is preservation of perceived video quality despite packet loss. Packet loss can be detrimental to compressed video. However, reducing packet loss to a very low level is difficult with current loss control techniques. Furthermore, even a very low objective loss probability can still seriously distort perceived video quality. This paper presents two buffer management schemes using video characteristics. They increase maximum loss tolerance for a desired level of video quality, providing better quality at equal loss ratios, when compared to a conventional buffer management scheme. Meanwhile, service fairness and network efficiency are also improved.     

Free volume and permeabilities of O2 and H2 in Nafion membranes for polymer electrolyte fuel cells

The mechanism of gas permeation in Nafion membranes for polymer electrolyte fuel cells has been investigated from the viewpoint of free volume. Three different samples, a membrane with ionic exchange capacity (IEC) = 0.92 meq/g, and recast samples with IEC = 0.92 and 1.00 meq/g were used after drying. Free volume was quantified using the positron annihilation lifetime (PAL) technique and gas permeabilities were measured for O₂ and H₂ as functions of temperature and relative humidity. Good linear correlations between the logarithm of the permeabilities at different temperatures and reciprocal free volume indicate that gas permeation in dry Nafion is governed by the free volume. Nevertheless permeabilities are much smaller than the corresponding flexible chain polymer with a similar free volume size due to stiff chains of the perfluoroethylene backbone. In highly hydrated Nafion above 60% relative humidity, where the O₂ permeability varies oppositely to the free volume, gas permeation proved to be controlled by the gradual increase in overall flexibility of the Nafion–water system.     

Effect of 8 MeV electron irradiation on electrical properties of CuInSe2 thin films

Radiation damages due to 8 MeV electron irradiation in electrical properties of CuInSe₂ thin films have been investigated. The n-type CuInSe₂ films in which the carrier concentration was about 3×10¹⁶ cm⁻³, were epitaxially grown on a GaAs(0 0 1) substrate by RF diode sputtering. No significant change in the electrical properties was observed under the electron fluence <3×10¹⁶ e cm⁻². As the electron fluence exceeded 10¹⁷ e cm⁻², both the carrier concentration and Hall mobility slightly decreased. The carrier removal rate was estimated to be about 0.8 cm⁻¹, which is slightly lower than that of III–V compound materials.     

Use of external conduit impairs liver function in patients with biliary atresia

An external conduit (stoma) for patients with biliary atresia has been used to prevent postoperative cholangitis. Thirty-two patients with biliary atresia who had hepatic portoenterostomies with external conduits were studied retrospectively with respect to frequency and severity of postoperative cholangitis or stoma bleeding. Changes in their liver enzyme levels, and total bilirubin (TB) levels were measured before and after closure of the stoma. Cholangitis was observed in 20 patients (62.5%), and major hemorrhage from the stoma site was seen in 14 patients (43.8%) prior to closure. Levels of liver enzymes such as glutamic oxaloacetic transaminase (SGOT), glutamic pyruvic transaminase (SGPT), gamma-glutamyl transpeptidase (gamma-GTP), and alkaline phosphatase (ALP) improved significantly within 1 month after closure of the stoma, and remained low thereafter. The TB concentration was the only liver function that did not change significantly following closure. In summary, the authors do not recommend an external conduit in patients with biliary atresia because it is not an effective way of reducing the incidence of postoperative cholangitis, and it may be deleterious to liver function.     

Patients with ultrasonic coarse-nodular cirrhosis who are anti-hepatitis C virus-positive are at high risk for hepatocellular carcinoma

BACKGROUND: The relationship between echosonographic patterns of patients with cirrhosis who are antihepatitis C virus (HCV)-positive, the DNA synthesis of hepatocytes, and the risk for HCC were studied. METHODS: Thirty-eight patients with anti-C-100 antibody-positive and Child's grade A posthepatitic cirrhosis were studied. DNA synthesis activity was measured by a bromodeoxyuridine (BrdU, a thymidine analogue)-labeling index (LI), using the BrdU-anti-BrdU in vitro method, and the patients were followed prospectively by frequent liver ultrasonography for 3 years. The ultrasound patterns were classified into fine, coarse, and coarse-nodular (CN) patterns, and the reproducibility of the classification in practical use also was confirmed. RESULTS: Of the 21 patients with high DNA synthesizing cirrhosis (BrdU LI > or = 1.5%), 10 (48%) showed coarse-nodular, 5 (24%) coarse, and 6 (29%) fine pattern in ultrasonography. Conversely, of the 17 patients with low DNA synthesizing LC (BrdU LI < 1.5%), only 1 (6%) showed coarse-nodular, 2 (12%) coarse, and 14 (82%) fine pattern. A significant relationship was found between the two groups of BrdU LI and ultrasound imaging patterns (P < 0.05). The incidence of CN pattern was significantly higher (P < 0.01) in the high DNA synthesizing group than in low DNA synthesizing group. Of the 11 patients with CN pattern by ultrasound imaging, 10 (91%) were in the high DNA synthesizing group, and 9 (82%) developed HCC during the follow-up period, compared with 3 of 7 (43%) with coarse, and only one of 20 (5%) with fine pattern developed HCC. The incidence of HCC was significantly higher (P < 0.01) in patients with a CN cirrhosis pattern than in those with a fine pattern. CONCLUSIONS: In patients with cirrhosis who are anti-HCV-positive, the CN pattern by ultrasound imaging indicates increased DNA synthesis of hepatocytes and a high risk for developing HCC.     

A 10 bit 20 MS/s 3 V supply CMOS A/D converter

A 10 bit CMOS A/D converter with 3 V power supply has been developed for being integrated into system VLSI's. In this A/D converter, redundant binary encoders named “twin encoders” enhance tolerance to substrate noise, together with employing differential amplifiers in comparators. The bias circuit using a replica of the amplifier is developed for biasing differential comparators with 3 V power supply. Subranging architecture along with a multilevel tree decoding structure improves dynamic performance of the ADC at 3 V power supply. The A/D converter is fabricated in double-polysilicon, double-metal, 0.8 μm CMOS technology. The experimental results show that the ADC operates at 20 MS/s and the twin encoders suppress the influence of substrate noise effectively. This ADC has a single power supply of 3 V, and dissipates 135 mW at 20 MS/s operation