80 GHz MMIC HEMT VCO

In this letter a monolithic voltage-controlled oscillator (VCO) operating in the 77.5-83.5 GHz range is presented. InP HEMTs are used for both the active device and varactor. The VCO demonstrated a tuning range of 6 GHz and an output power better than 12.5 dBm in the entire tuning range     

Hospital experience and hospital mortality following partial pancreaticoduodenectomy in The Netherlands

OBJECTIVE: To analyse the effect of hospital experience on mortality after subtotal pancreaticoduodenectomy in the Netherlands. DESIGN: Retrospective evaluation. METHOD: Information on hospital mortality and pancreatic resection in 1994 and 1995 in the Netherlands was obtained from the National Medical Register. Subanalysis was carried out of surgical mortality by age and hospital experience. RESULTS: Approximately 50% of the pancreaticoduodenectomies in the Netherlands were performed in hospitals with limited experience (< 5 procedures per year). Hospital mortality was higher in small-volume hospitals than in hospitals with experience (> 25 procedures per year): in 1994 17.2 and 0% and in 1995 14.6 and 2.9%, respectively (p < 0.05). Mortality was higher in patients older than 70 years compared with patients younger than 55 (p < 0.05). CONCLUSION: There was a correlation between mortality after pancreaticoduodenectomy and hospital experience. Therefore these procedures should be performed in centres with experience.     

The relation between induced abortion and ectopic pregnancy

The present study was conducted to elucidate the effects of tirilazad mesylate (U-74006F), a potent inhibitor of lipid peroxidation, on vessel diameter, capillary perfusion, and contractile function of rat cremaster muscle during a 90-minute reperfusion period that followed 4 hours of warm ischemia. Two groups of 32 animals were treated with either 3 mg/kg U-74006F or the vehicle (citrate buffer) alone 30 minutes before ischemia, 90 minutes after ischemia, and immediately before reperfusion. With use of intravital videomicroscopy, the internal luminal diameters of preselected vessels were measured prior to ischemia and during reperfusion. The area that filled with fluorescein was determined at 15-minute intervals for as long as 90 minutes of reperfusion, and contractile function was examined in vitro in an organ bath at that point. In the U-74006F group, after 90 minutes of reperfusion the vessel diameters returned completely to baseline and the diameters of all three categories of vessels at every time point from 10 to 90 minutes of reperfusion had significantly more rapid recovery than the controls. Although some evidence of more rapid fluorescence was noted in the U-74006F group, the two groups did not differ significantly at any time period of reperfusion. In response to tetanic stimulation, the muscles treated with U-74006F had a significantly greater contractile force at all stimulation frequencies than the control muscles. Our findings indicate that pretreatment with U-74006F can effectively decrease the rise of vascular resistance and preserve the contractile function of skeletal muscle during early reperfusion, thereby attenuating ischemia-reperfusion injury.     

Fast pyrolysis of palm kernel cake using a fluidized bed reactor: Design of experiment and characteristics of bio-oil

In this study, the central composite rotatable design (CCRD) was employed to investigate the effects of the feedstock feed rate, biomass particle size, pyrolysis temperature, and residence time on the fast pyrolysis of palm kernel cake. A mathematical model for the liquid product yield was developed and applied to obtain a maximum yield of 49.5 wt%. The GC–MS analyses of the bio-oils at the two different temperatures of 400 and 500 °C showed that they were a complex mixture composed of mostly oxygenated compounds including β-D-allose, derivatives of furan and phenol, and a considerable amount of fatty acids.     

Milling contour error control using multilevel fuzzy controller

Machining contour error plays important roles in product quality. This paper presents an implementation of multilevel fuzzy controller in controlling contour errors while maintaining the desired feed rate of milling processes. The orthogonal global task frame was used to transform the tool positions from the Cartesian coordinate system to the curvilinear coordinate system. Contour error and tracking lag error calculated from the curvilinear coordinate system were used by the multilevel fuzzy controller to drive the machining axis on the Mazak VQC-15/40 vertical machining center. The contour error of the machined work piece measured by the coordinate measuring machine showed that the contour error were significantly reduced and the feed rate were regulated at the desired speed.