Estimation of process parameter variations in a pre-defined process window using a Latin hypercube method

The aim of this paper is to present a methodology that provides an analytical tool for estimation of robustness and response variation within a pre-defined process window. To exemplify the developed methodology, the stochastic simulation technique is used for a sheet-metal forming application. A sampling plan based on the Latin hypercube sampling method for variation of design parameters is utilized, and the thickness reduction is specified as the response. Moreover, the response surface methodology is applied for understanding the quantitative relationship between design parameters and response value. The conclusions of this study are that the applied method gives a possibility to illustrate and interpret the variation of the response versus a design parameter variation. Consequently, it gives significant insights into the usefulness of individual design parameters. It has been shown that the method enables us to estimate the admissible design parameter variations and to predict the actual safe margin for given process parameters. Furthermore, the dominating design parameters can be predicated using sensitivity analysis, and this in its turn clarifies how the reliability criteria are met. Finally, the developed software can be used as an additional module for set-up of stochastic finite element simulations and to collect the numerical results from different solvers within different applications.     

Comparison of a radioallergosorbent (RAST) inhibition method and a monoclonal enzyme linked immunosorbent assay (ELISA) for aeroallergen measurement

BACKGROUND: Mouse and rat urinary proteins are potent occupational allergens for exposed personnel. Methods of measuring airborne allergens differ greatly, and reported levels of allergens vary considerably between laboratories. OBJECTIVES: To compare the values obtained using two different methods of allergen detection. METHODS: Air samples were collected in rat rooms in Sweden and the United Kingdom at 2 L/min on to polytetrafluoroethylene (PTFE) filters and extracted in buffer containing 0.5% v/v Tween 20. Airborne rat urinary allergen (RUA) was measured in all samples by both RAST inhibition using a polyclonal human serum pool (UK) and a two monoclonal antibody sandwich ELISA employing antibodies specific for Rat n 1.02 (alpha2u-globulin) (Sweden). RESULTS: The two methods gave values which were correlated (r2 log values = 0.72, P<0.0001), but differed by several orders of magnitude (median [range] ratio of RAST inhibition/ELISA = 316 [7-26(80)]. There was a systematic bias: as the absolute values increased, the difference in the measurements increased. The rat urine standards used were antigenically similar. CONCLUSIONS: A large contrast in RUA values obtained from the two assays was observed in this study. This may be primarily due to methodological differences, but variations in antibody specificities or composition of allergenic epitopes in the air samples may contribute. The results demonstrate that standardization of methods and antibodies is necessary before interlaboratory comparisons can be made.     

Semantic factors in episodic recognition of common odors in early and late adulthood: a review

Information on long-term memory for common odors is discussed. Olfactory parameters (i.e. familiarity, recognition, identification) and their relationship to current memory theory are highlighted. Emphasis is focused on the impact of semantic memory on episodic odor recognition. In contrast to previous research suggesting that verbal/semantic factors play a negligible role in olfactory memory, the present review indicates that episodic odor information is mediated by factors that can be subsumed under the rubric of semantic memory. Specific odor knowledge, such as perceived familiarity and identifiability, is strongly and positively related to episodic odor memory performance. Age-related impairments in various olfactory and cognitive parameters and the potential detrimental effects in episodic odor memory are discussed. Finally, the issue of whether olfactory memory should be conceptualized as an independent process, or whether it shares characteristics with memory for verbal and visual information, is addressed.     

Beneficial role of human endogenous retroviruses: facts and hypotheses

Human endogenous retroviruses (HERVs) have recently been suggested as mediators of normal biological processes such as cellular differentiation and regulation of gene expression. Moreover, a direct role for HERVs in pathogenesis and the development of disease is now better appreciated. Elucidation of the mechanisms regulating HERV biology should provide information about fundamental cellular activities and the pathogenesis of multifactorial diseases such as cancer and autoimmune disease. The importance of understanding the roles of HERVs is underscored by the recently obtained insight that activation of endogenous retroviruses poses potential risks following xenotransplantation and in gene therapy using retroviral vectors. Furthermore, HERV-encoded superantigens have recently been implicated as causes of autoimmune disease. This review discusses the established and possible biological roles of HERVs, and proposes hypotheses concerning their involvement as mediators of fundamental cellular responses. We propose that the evolutionary persistence of endogenous retroviruses in the genomes of eukaryotic cells reflects their indispensability in important normal functions in specialized cellular environments. HERVs can also be potentially hazardous through their involvement in the development of disease. In addition, the creation of new retroviruses can occur through recombination, between different HERVs and between HERVs and exogenous retroviruses.     

The Fractional Extraction of Lipids and Cholesterol from Dried Egg Yolk Using Supercritical Carbon Dioxide

Results from extraction of cholesterol and other lipid components from dried egg yolk using supercritical carbon dioxide at the range of temperature from 40°C to 60°C and pressure between 150 bar und 350 bar for 2.5 hours and 2.7 kg CO₂ consumption is described in this paper. The solubility of lipids and cholesterol increased with the increase of pressure at a constant temperature of 50°C, while at a constant pressure, more cholesterol was removed at 45°C than that at other temperatures. Nearly 60 percent cholesterol was removed at 45°C and 250 bar. Lipids were more efficiently extracted at 60°C than at 40°C at 250 and 350 bar, however, a decrease in the total extracted lipids was observed with the increase in temperature at 150 bar. The removed total lipids from dried egg yolk at 250 bar/55°C was over 80 %.     

InP-based optically pumped VECSEL operating CW at 1550 nm

We present a vertical external-cavity surface-emitting laser operating at 1550 nm. The laser comprises an InGaAsP-based gain element, with a resonant periodic gain structure on top of a distributed Bragg reflector, and a high reflectivity spherical mirror as the external reflector. Optical pumping is achieved using a 1250-nm fiber Raman laser. A maximum continuous output power of 70 mW was obtained under multitransverse mode operation at 233 K. Under single-mode operation, we obtained a maximum power of 60 mW with a beam quality factor M/sup 2/ less than 1.1.     

Improving the frame-error-rate of spatial multiplexing in block fading by randomly rotating the signal constellation

We demonstrate that one can improve the coded frame-error-rate of spatial multiplexing in block fading by randomly rotating the signal constellation. Unlike linear precoding, our method: 1) does not require coding over time and 2) brings a performance improvement at essentially no additional computational expense. A discussion of the results is provided.     

Electrical impedance — a new parameter for oral mucosal irritation tests

The potential for dental materials to irritate human oral mucosal membranes was assessed by an electrical impedance technique. A small electrode at the site of irritation on the inside of the cheek and a large electrode on the outside of the cheek were used. Skin impedance was reduced by inundation with ECG-gel. An irritation index was formed by calculating the quotient between the impedance absolute value at 20 kHz and the impedance value at 1 MHz. Electrical impedance technology was found to be more sensitive than traditional visual registration of mucosal reactions. Two series of experiments were performed in which special appliances were constructed to ensure duplicate measurements on the small area of exposed buccal mucosa. Liquid samples elicited differentiated fast response, which was insignificantly influenced by mechanical factors. The mechanical irritation induced by merely the shape of a solid specimen prevents detection of slight mucosal irritation from potentially leaking substances.     

Anode slimes treatment: The boliden experience

There are numerous approaches to the treatment of both copper and lead anode slimes. Although the chemistry and metallurgy has been described and discussed by many authors, few, if any, have described the environmental impact of these activities. Dust and especially selenium emissions are a problem both in the internal working environment as well as in the external environment. For more information, contact B.M. Ludvigsson, Boliden Contech AB, P.O. Box 745 Skelleftea 93127, Sweden; e-mail bjorn.ludvigsson@contech.boliden.se.