Lars Pallesen

Economic Selection of Quality Manufactured Product

In this article an economic analysis is presented for the problem of selecting the most favorable quality distribution for an industrial process. An important special case is that of selecting the best mean (target) value. The analysis, which takes into account the stochastic nature of the process, is illustrated by considering the problem of choosing the optimal amount of overfill in a filling operation. A detailed solution is given for situations in which the distribution of the quality measurements is approximately normal; for that case a table is provided that simplifies the solution of the problem in practice. Industrial examples are considered. Lognormal and Poisson distributions are also discussed.

Chimeric FimH adhesin of type 1 fimbriae: a bacterial surface display system for heterologous sequences

The FimH adhesin of type 1 fimbriae has been tested as a display system for heterologous protein segments on the surface of Escherichia coli. This was carried out by introduction of restriction site handles (BglII sites) in two different positions in the fimH gene, followed by in-frame insertion of heterologous DNA segments encoding two reporter sequences. In the selected positions such insertions did not significantly alter the function of the FimH protein with regard to surface location and adhesive ability. The system seemed to be quite flexible, since chimeric versions of the FimH adhesin containing as many as 56 foreign amino acids were transported to the bacterial surface as components of the fimbrial organelles. Furthermore, the foreign protein segments were recognized by insert-specific antibodies when expressed within chimeric proteins on the surface of the bacteria. The results from this feasibility study point to the possibility of using the FimH adhesin as a general surface display system for sizeable protein segments.

Authentic display of a cholera toxin epitope by chimeric type 1 fimbriae: effects of insert position and host background.

The potential of the major structural protein of type 1 fimbriae as a display system for heterologous sequences was tested. As a reporter-epitope, a heterologous sequence mimicking a neutralizing epitope of the cholera toxin B chain was inserted, in one or two copies, into four different positions in the fimA gene. This was carried out by introduction of new restriction sites by PCR-mediated site-directed mutagenesis of fimA in positions predicted to correspond to optimally surface-located regions of the subunit protein. Subsequently, the synthetic cholera-toxin-encoding DNA segment was inserted. Several of the chosen positions seemed amenable even for large foreign inserts; the chimeric proteins were exposed on the bacterial surface and the cholera toxin epitope was authentically displayed, i.e. it was recognized on bacteria by specific antiserum. Display of chimeric fimbriae was tested with respect to host background in three different Escherichia coli strains, i.e. an isogenic set of K-12 strains, differing in the presence of an indigenous fim gene cluster, as well as a wild-type isolate. Immunization of rabbits with purified chimeric fimbriae resulted in serum which specifically recognized cholera toxin B chain, confirming the utility of the employed strategy.

Environmental intervention analysis: Wisconsin's ban on phosphate detergents

Abstract Intervention analysis is a method of assessing the effect of a deliberate change to a system when the data record is a time series. A statistical analysis that assumes fixed mean levels before and after the intervention often is inappropriate for environmental time series, because typically environmental systems display some random drift in level over time, unrelated to the intervention itself. A reliable estimate of the effect of the intervention must taken into account such drift. The method presented does this by using suitably weighted averages of observations before and after the intervention; also it can allow for a gap in time over which the intervention gradually realizes its full effect. The method has been used to estimate the decrease in total phosphorus load on the two large wastewater treatment plants in Milwaukee, WI, caused by the ban on phosphate laundry detergents that went into force on July 1, 1979. The estimated effect was equivalent to 0.506 kg P per capita per year. The result of this ban being lifted in 1982 was also estimated; the increase in total P loading was equivalent to 0.187 kg P per capita per year.

Statistical assessment of PCDD and PCDF emission data

Real PCDD and PCDF emission data from a statistically planned measurement programme at Amagerforbraending, Copenhagen, 1985 are analyzed. It is demonstrated how statistical analysis of variance can be used to break down the total variability in the data into interpretable components. Crossed and nested data structures are considered. Emission differences over time are significant, but less so than differences due to alternative sample taking methods, and even greater differences were found between laboratories.

Intervention Analysis of Seasonal and Nonseasonal Data to Estimate Treatment Plant Phosphorus Loading Shifts

Publisher Summary This chapter presents an intervention analysis of seasonal and nonseasonal data to estimate treatment plant phosphorus loading shifts. In the non-seasonal model, an exponentially weighted moving average (EWMA) is used to estimate the levels immediately before and after the gap. The magnitude of the effect of the intervention is the difference of the two, since the forecast for ARIMA or observation error/random walk mode. The seasonal model incorporates an annual pattern, but it is not a deterministic sine pattern; instead, it allows more flexibility. The smoothness-prior state space approach was used in a study given in the chapter to estimate the intervention effect. The calculations required for analysis of the non-seasonal and seasonal data sets were readily programmed in APL and carried out on a microcomputer. An ARIMA time series model has been used successfully on about sixty percent of the dataset analyzed to date. A seasonal model has been successfully applied to three data sets. The model may possibly be adequate for the remaining sets. The effect of a detergent phosphate ban on influent wastewater treatment plant P loads appears to be about 0.3 kg/cap. yr.