Principles of antibiotic therapy

The primary development in the area of antibiotic treatment for surgical infections in the last 5 years has been the expanded clinical importance of beta-lactamases in the protection of Gram-negative organisms from previously active drugs. To counter this problem, a series of new antibiotic agents has been developed, including new cephalosporins, carbapenems, quinolones, and beta-lactamase inhibitors. This article describes the various beta-lactamases and their mechanisms of action, and details the activity of new antibiotic agents against resistant Gram-negative organisms. Recent information on the importance of combination therapy for patients with severe Gram-negative infections is reviewed. The use of optimized aminoglycoside dosing regimens, including once-a-day dosing, provides an additional strategy for treating serious Gram-negative infections.     

Analysis of low fixed pattern noise cell structures forphotoconversion layer overlaid CCD or CMOS image sensors

A new low fixed pattern noise (FPN) cell structure, which can be used for photoconversion layer overlaid CCD or CMOS image sensors, was proposed and analyzed with a two-dimensional (2-D) device simulator. One of the most serious problems for this type of image sensor is the mixing of signal charges of neighboring cells during signal charge readout. The magnitude of signal mixing was as much as 20% for the conventional 2/3-in 2-million pixel STACK-CCD cell structure. FPN was very visible as a result of this signal mixing. This time, a new cell structure was proposed and analyzed to reduce signal mixing and FPN. It was possible to reduce signal mixing to a low value of 0.7% of the signal level using the new cell structure     

Barrier effect under nonuniform field in atmospheric pressure SF6 gas

Generally, it is known that insertion of a barrier under a nonuniform field in air increases the flashover voltage. This is called the barrier effect. However, there are many uncertainties that remain to be clarified about the barrier effect in SF₆ gas. Therefore, the influence of the barrier shapes and positions on the flashover voltage for the lightning impulse voltages and voltages (50 Hz) is examined by inserting a barrier between a hemispheric-end rod and a plate in SF₆ gas under near-atmospheric pressure. As a result, the following findings were obtained:. (1) Insertion of a disk-shaped barrier reduces the flashover voltage; a cup-shaped barrier whose surface curves almost along the equipotential line increased the flashover voltage by 30 to 40 percent;. (2) trapped charge on the barrier surface is of the same polarity as the applied voltage and the magnitude of positive charge was greater than that of negative charge. It was found also that there is a correlation between the amount of trapped charge and the flashover voltage; and. (3) application of a barrier under a nonuniform field in the atmospheric pressure SF₆ gas helps reduce the size of, for example, a cubic-type gas-insulated switchgear.     

Photodegradation for a hydrogenated amorphous siliconphotoconversion layer in a solid-state image sensor

Photodegradation for a hydrogenated amorphous silicon photoconversion layer in a two-level solid-state imaging device was studied. The residual current after a light pulse, which causes image lag for the imaging device, was most sensitive to light exposure among several properties, so that the residual current determines the lifetime for the photoconversion layer. The space charge was also increased with increasing residual current by light exposure, because both properties reflected light-induced defect states. The space charge was found to be a good monitor for the photodegradation. The space-charge density had light intensity and exposure-time dependency, which is similar to that for dangling bond density. The lifetime for the photoconversion layer, which was evaluated through the space-charge density change, was 1.5×10⁷ h under standard illumination for the imager. This lifetime is sufficiently long for practical imager use     

A 2-million-pixel CCD image sensor overlaid with an amorphoussilicon photoconversion layer

A highly sensitive 2-million-pixel high-definition charge-coupled device (CCD) image sensor was developed that features an overlaid amorphous silicon photoconversion layer on an interline transfer-type CCD scanner. The device is adapted to the 16:9 aspect ratio. 1125 scanning lines and 2:1 interlace high-definition TV system. A dual-channel horizontal CCD register is used to reduce the operating frequency to one half of the 74.25-MHz readout frequency. A horizontal period signal storage memory (1H line memory) is provided between the vertical CCD register and the horizontal CCD register to provide the signal distribution from the vertical CCD to the horizontal CCD register during the 3.77-μs short horizontal blanking interval. This device realized a 1000 TV line horizontal limiting resolution 210 nA/1x high sensitivity. Total random noise was found to be 52 electrons RMS and a 72-dB dynamic range was achieved     

Increase of breakdown voltage due to composite insulation in SF6 gas

The breakdown characteristics using a hemispherical tip rod (10 ～ 60 mm) molded with epoxy resin-to-plate gap in SF₆ gas up to 0.20 MPa was studied. The result shows that breakdown characteristics are classified into three regions (A, B and C region) depending on gap length. In the A-region breakdown voltage is lowered compared with bare hemispherical tip rod-to-plate gap. In the B-region breakdown voltage is raised sharply with gap length and in the C-region it saturates. The maximum increase ratio of breakdown voltage in the B and C region are 1.95 times (ac) and 1.68 times (impulse) compared with a bare hemispherical tip rod-to-plate gap characteristic. The ratios depend on the diameter of the spherical tip rod and the thickness of epoxy resin. It is concluded that the increase of breakdown voltage is attributed to the synergism effect of the decrease of maximum electric field strength by epoxy resin and the suppression of field emission. The use of composite insulation reduces the gap length drastically in the gas-insulated switchgear, for instance, C-GIS (Cubicle-type Gas-Insulated Switchgear).     

Electrical resistivity changes due to interstitial hydrogen in palladium-rich substitutional alloys

The changes in electrical resistivity of palladium solid solution alloys (alloying element = silver, gold, copper, yttrium, cerium, titanium, zirconium, vanadium, niobium and tantalum) with hydrogen concentration were measured at 301 K up to aboutr(H/M) = 1.5×10^–2; the hydrogen was introduced by electrolysis and measurements of electrode potential were also made. The specific electrical resistivity increment per unit change of hydrogen concentration, 1r, generally increases with increase of the solute contents, although for silver, gold and copper there are no notable changes in the slopes with their concentrations. The increase in /g9/r with the alloying contents cannot be related to the lattice dilatation effect due to the solute, but it is associated approximately with a decrease in the density-of-states at the Fermi level caused by pre-filling of the 4 d band of palladium by the solute atoms.     

Anti-Ro/SSA-associated annular erythema in childhood

We report four children with anti-Ro/SSA positive who presented with an annular erythema as a manifestation of Sj?gren's syndrome. One patient had an aseptic meningoencephalitis as well as cutaneous lesions. Children with annular erythema should be carefully followed for features of Sj?gren's syndrome, which is believed to be a rare condition in children.     

A 10 Gb/s high sensitivity, monolithically integrated p-i-n-HEMToptical receiver

A high-sensitivity, monolithically integrated optical receiver, composed of a p-i-n-PD and high electron mobility transistors (p-i-n-HEMTs) is described. The receiver sensitivity is -17.3 dBm at a bit error rate of 1×10^-9 for a 10-Gb/s non-return-to-zero (NRZ) lightwave signal. This value is the best result yet reported for 10-Gb/s monolithically integrated receivers. The sensitivity is -30.6 dBm if an erbium-doped fiber amplifier (EDFA) is placed ahead of the p-i-n-NEMT receiver. A transmission experiment using a 150-km dispersion-shifted fiber (DSF) indicates no degradation in the bit error rate characteristics or the eye pattern. This verifies the practicality of the p-i-n-HEMT optical receiver for high-speed transmission systems     

Resection for multiple metastatic liver tumors after portal embolization

BACKGROUND: Five patients with bilateral multiple liver metastases (3 to 12 lesions) from colorectal cancer who underwent extensive liver resection after portal embolization are described. METHODS: Portal embolization of the right portal branch was performed 9 days to 8 months before hepatic resection. The location and number of metastases were determined by intraoperative ultrasonography at the time of liver resection to accomplish complete resection of the tumors. Extended right lobectomy was carried out in four patients, two of whom underwent additional wedge resection of nodules located in the left lateral segment. The other patient underwent right lobectomy associated with local resection of the tumor in the left lobe. RESULTS: The postoperative course in the five patients was uneventful, with no serious complication or liver dysfunction. Although one patient died of recurrence 28 months after liver resection, the remaining four patients were alive and free of cancer between 36 and 74 months after hepatectomy. CONCLUSIONS: The presence of bilateral multiple (four or more) metastatic liver lesions from colorectal cancer is not considered a contraindication for hepatic resection if thorough examination of the liver is performed with intraoperative ultrasonography and the surgical risk is minimal. Portal embolization appears effective for increasing the safety of hepatectomy for patients with small metastases who require major right-sided resection combined with wedge resection of the left lobe.