Cpk index estimation using data transformation

Process capability indices (PCIs) are used in industry to assess percentages of nonconforming parts. An underlying assumption is that the output process measurements are distributed as normal random variables. When normal distributions are assumed, but different distributions are present - such as skew, heavy-tailed, and short-tailed distributions - the percentages of nonconforming parts are significantly different than the computed PCIs indicate. Data arising from nonnormal distributions can sometimes be transformed to conform to the normality assumption and the PCI's computed for the transformed data. In this paper, the effect of the transformation on the estimate of nonconforming parts is examined for three examples of nonnormal distributions - gamma, lognormal, and Weibull. The results of this experimental analysis suggest that data transformation can be useful for estimating an interval for C_pk values and the number of nonconforming parts.     

Postoperative fistulas after gastrectomy: risk factors in relation to incidence and mortality

The relations between incidence and prognosis of postoperative fistulas after gastrectomy and some different variables were analysed in the present retrospective study. Thirteen digestive fistulas of 113 patients (11.9%) submitted to gastrectomy during the period 1989-1994 represent the study population. The incidence of postoperative fistulas was compared to the kind of gastric pathology, to the extension of gastrectomy, to different nutritional (serum haemoglobin, albumin and transferrin level, weight loss) and immunological factors (serum lymphocytes) and, for oncological patients, to the stage of the disease. Incidence was directly related to the extension of gastrectomy, to serum albumin and haemoglobin level, and to weight loss rate. The results were not statistically significant at Kruskal-Wallis and ANOVA tests. No relation was found between incidence of fistulas and serum transferrin level, number of lymphocytes and adoption of early postoperative enteral nutrition. Six patients had spontaneous closure of the fistula with conservative therapy. Seven patients required reoperation because of abdominal sepsis (53.8%). Three patients died (23%). Although spontaneous closure, reoperation and mortality were related to nutritional and immunological state, no examined variables showed a statistically significative relation. The adoption of early postoperative enteral nutrition was not related to the prognosis, unlike the stage of the disease: patients submitted to reoperation had a TNM III or IV stage; dead patients had a TNM IV stage. Treatment of metabolic-nutritional unbalance can prevent anastomotic failure and fistula after gastrectomy and improve the prognosis. The relation between early postoperative enteral nutrition and incidence and prognosis of postoperative fistulas remains unclear.     

Patterns of messenger RNA expression for alpha1-adrenoceptor subtypes in human corpus cavernosum

PURPOSE: The present study evaluated the expression of alpha1-adrenoceptor subtypes in human corpus cavernosum. MATERIALS AND METHODS: The mRNA encoding alpha1a, alpha1b and alpha1d subtypes were assessed by RNA-directed complementary cDNA synthesis followed by Taq DNA amplification. The level of alpha1 mRNA was calculated in arbitrary optical density units and normalized with respect to the length of the respective cDNA fragments. RESULTS: We found that alpha1a, alpha1b and alpha1d adrenoceptor subtypes are expressed in human corpus cavernosum, with a predominant expression of the alpha1a subtype. CONCLUSION: These results suggest that alpha1a-adrenoceptor subtype is important and that understanding the biochemical and functional characteristics of this subtype may lead to the development of specific antagonists in the treatment of impotence.     

CMOS low-distortion high-frequency variable-gain amplifier

The overall system performance of mixed-signal CMOS IC's is largely determined by the dynamic performance of the analog front-ends. System features are, in contrast, mainly set by the digital architecture. In order to optimize the dynamic range of the system and to minimize the sensitivity to substrate noise, the analog-to-digital converter (ADC) has to be preceded by a variable-gain amplifier (VGA) and a differential circuit topology for the complete front-end to be adopted. Since most of present-day applications are based on single-sided signal source definitions, the differential-input VGA must be able to perform a single-to-differential signal conversion. This paper describes the principle and design of a differential CMOS low-distortion variable-gain amplifier for high-frequency (video) applications. Experimental results of the circuit show total harmonic distortion figures better than -60 dB and a gain accuracy of 0.05 dB over the -2 to +12 dB gain range for single-sided input signals     

Use of the ARPE-19 cell line as a model of RPE polarity: basolateral secretion of FGF5

PURPOSE: To determine the polarity of fibroblast growth factor 5 (FGF5) secretions from retinal pigment epithelium (RPE) cells and to examine the viability and utility of the ARPE-19 cell line as a model for the study of RPE polarity. METHODS: Influenza infection and adenovirus-mediated gene transfer were used to deliver and express genes encoding influenza hemagglutinin (HA), p75-NTR (a neurotrophin receptor), low-density lipoprotein (LDL) receptor (LDLR), and FGF5 in confluent monolayers of ARPE-19 cells. The localization of HA, p75-NTR, and LDLR was determined by confocal microscopy. Domain selective biotinylation assays were used to quantitatively determine the polarities of p75-NTR and LDLR. The secretion of FGF5 into the apical and basal media of ARPE-19 cultures was examined by immunoblot analysis of conditioned media. RESULTS: Hemagglutinin and p75-NTR were found to be localized on the apical surface of infected and transduced ARPE-19 cells. In contrast, LDLR was associated preferentially with the basolateral membrane of ARPE-19 cells. Biotinylation studies indicated that 84% of p75-NTR was present on the apical surface, and 79% of LDLR was basolaterally polarized. Over the course of 6 hours, more than 90% of the total secreted FGF5 protein accumulated in the basolateral media. CONCLUSIONS: ARPE-19 cells exhibit a polarized distribution of cell surface markers when examined by either confocal microscopy or surface-labeling assays. This indicates that the ARPE-19 cell line is a valid model for studies of RPE cell polarity. FGF5, a secreted protein normally produced by RPE cells, is accumulated preferentially in the basal media after only 6 hours, suggesting that it is vectorially secreted from the basolateral surface of ARPE-19 cells.     

Korrosionsverhalten von Plasma- Heißdraht-Auftrag-Schweißungen. Teil I: Beständigkeit von auftraggeschweißten Nickelbasislegierungen gegen Loch- und interkristalline Korrosion

The corrosion properties of Plasma-Hot-Wire-Surfacing Part one: resistance of Nickel-base-alloy claddings against pitting and intergranular attack This paper describes measurements at claddings of nickel-based-alloys C 276, C 4 and C 22 on the St 52-3 steel substrat produced by Plasma-Hot-Wire-Surfacing (PHS). The correct heat control during the welding process is a crucial factor for the preparation of nearly precipitate-free claddings. For this reason it was necessary to optimize all the process data. The claddings itself as well as the rolled reference material (both of nearly the same chemical composition) were examined by means of metallografical and microanalytical techniques. Corrosion measurements show, that the composite materials exhibit high resistance both against pitting and intergranular corrosion and comparable to the properties of the rolled reference material. This was shown by determination of the critical pitting temperature in quinary salt solution, by electrochemical techniques in acidic chloride solution and by investigation in iron-(III)-sulfate-sulphuric acid solution.