High bit density (100 Mb/cm2) with single-layer Co-Crmedia and ring heads in perpendicular magnetic recording

The signal and noise of single-layer Co₇₉Cr₂₁ media are measured with ring heads to estimate the area density that can be achieved. Densities as high as 100 Mb/cm² (1 μm²/bit) are expected when a signal-to-noise ratio sufficient for an error probability less than 10 ^-5 is required. As a comparison, densities estimated from data from metal-evaporated tape and CrO₂ tape are given. In the frequency response of the single-layer media, an additional minimum was observed for a wavelength slightly larger than the gap length. This is probably caused by the bipolar nature of the perpendicular recording field of a ring head     

Noise of low-coercivity single-layer perpendicular recording media

The noise of single layer CoCr media is investigated. A model is developed by treating the medium as a collection of columns. It appears that there is a strong correlation between magnetization direction of the columns. Neighbouring columns tend to have the same magnetization polarity, indicating exchange interaction. It is concluded that the media consist of domains. The domain width increases with the medium thickness. These domains can also result in a poor signal response at short wavelength.     

Late results after resection of benign hepatic tumors: clinical and radiological findings

Our previous work showed the existence of low molecular weight tumor suppressors in human fetal tissues. In this paper, two tumor cell suppressors were isolated and purified from methanol extract of human fetal liver by C18 reversed-phase medium pressure chromatography, gel filtration on Sephadex LH-20, and high-performance liquid chromatography, directed by suppression of growth of HL-60 cells. The structures of the suppressors were identified to be 7-ketocholesterol and 7-beta-hydroxycholesterol. Under the condition of in vitro agar plate culture, 7-ketocholesterol and 7-beta-hydroxycholesterol showed preferentially inhibitory effects on the growth of both human and murine leukemic cell lines including human HL-60 and murine S-180 cells, but less effective on the growth of normal human and murine bone marrow granulocyte-macrophage progenitors (CFU-GM).     

Impact ionization in thin silicon diodes

We study the breakdown behavior of thin, abrupt silicon pin-diodes, using a low-power optical technique which can directly measure the avalanche multiplication factors even in the presence of large tunneling currents. Our measurements agree with a simple model for nonlocal avalanche generation, and we use this model to extend the breakdown predictions to a broad class of doped diodes similar to those found in the base-collector region of bipolar devices. Based on this analysis, we make quantitative estimates for the BV/sub CEO/ breakdown of modern Si and SiGe high-speed bipolar transistors.     

Diagnosis and therapy of postoperative chyloperitoneum

Chyloperitoneum is a rare complication of surgical procedures. We report a case of severe chyloperitoneum after abdominothoracic esophageal resection with two-field lymphadenectomy. After diagnosis was established, the lymph leak was located with oral iodine-marked fatty acids (123I-pentadecanoic acid) showing increased activation in the right middle abdomen. Because conservative treatment with total parenteral nutrition showed no decrease in chyle volume, relaparatomy was performed and the lymphatic fistula was successfully treated with suture ligatures. Pathophysiology and different options for localization and treatment of postoperative chyloperitoneum are discussed.     

Photo carrier generation in bipolar transistors

Anomalous substrate currents have been observed in SiGe bipolar NPN-transistors, dependent on the collector bias, at high current levels. These currents appear to originate from light that is generated in the collector base junction when it is reverse biased. This light generates electron hole pairs in the n⁺ buried layer-substrate diode, yielding a considerable substrate current. This paper will show that these substrate currents can be used as a useful monitor for the occurrence of avalanche multiplication and high-level injection (Kirk effect) in heterojunction bipolar transistors (HBTs)     

The write field of a ring head for a double layer perpendicular medium

The write field of a ring head used with the preferred medium for perpendicular recording (CoCr with an underlayer of softmagnetic material) is discussed and compared with the write field of a Thin- -Film Single Pole (TF-SP) head on the basis of two-dimensional calculations. It is found that the saturation of the underlayer plays an important role in the shape as well as the magnitude of the calculated write field.     

A back-wafer contacted silicon-on-glass integrated bipolar process. Part I. The conflict electrical versus thermal isolation

A novel silicon-on-glass integrated bipolar technology is presented. The transfer to glass is performed by gluing and subsequent removal of the bulk silicon to a buried oxide layer. Low-ohmic collector contacts are processed on the back-wafer by implantation and dopant activation by excimer laser annealing. The improved electrical isolation with reduced collector-base capacitance, collector resistance and substrate capacitance, also provide an extremely good thermal isolation. The devices are electrothermally characterized in relationship to different heat-spreader designs by electrical measurement and nematic liquid crystal imaging. Accurate values of the temperature at thermal breakdown and thermal resistance are extracted from current-controlled Gummel plot measurements.     

The impact of patient's age on surgical therapy of colorectal liver metastases

In a consecutive series of 90 hepatic resections for colorectal liver metastases which were performed during a 10-year period at one institution, the influence of patient's age on surgical strategies and postoperative results was investigated. The mean age of all patients was 61 +/- 11 years with a range from 27-78 years; 19 patients (21%) were younger than 50 years and 18 patients (20%) were older than 70 years. Thirty-six (40%) major and 54 (60%) minor hepatic resections were performed. The postoperative complication rate was 26% and resection mortality 3%. Estimated overall median survival time was 27 months, operative mortality included. 1-, 3-, and 5-year survival rates were 78%, 45%, and 32%, respectively. Although there is some suggestion that selection criteria are more aggressive in younger patients, neither surgical procedures nor postoperative results were found to be determined by the numeric age of the patient in a significant way.