Evaluation of migration models that might be used in support of regulations for food-contact plastics

Materials and articles intended to come into contact with food must be shown to be safe because they might interact with food during processing, storage and the transportation of foodstuffs. Framework Directive 89/109/EEC and its related specific Directives provide this safety basis for the protection of the consumer against inadmissible chemical contamination from food-contact materials. Recently, the European Commission charged an international group of experts to demonstrate that migration modelling can be regarded as a valid and reliable tool to calculate 'reasonable worst-case' migration rates from the most important food-contact plastics into the European Union official food simulants. The paper summarizes the main steps followed to build up and validate a migration estimation model that can be used, for a series of plastic food-contact materials and migrants, for regulatory purposes. Analytical solutions of the diffusion equation in conjunction with an 'upper limit' equation for the migrant diffusion coefficient, D_P, and the use of 'worst case' partitioning coefficients K_P,F were used in the migration model. The results obtained were then validated, at a confidence level of 95%, by comparison with the available experimental evidence. The successful accomplishment of the goals of this project is reflected by the fact that in Directive 2002/72/EC, the European Commission included the mathematical modelling as an alternative tool to determine migration rates for compliance purposes.     

Proteolytic cleavage of Gram-positive recombinase is required for crystallization

ß Recombinase, a DNA resolvase-invertase, catalyzes inthe presence of a chromatin-associated protein such as Hbsu,DNA resolution or DNA inversion on supercoiled substrates containingtwo directly or inversely oriented target (six) sites. Singlecrystals of the ß recombinase from plasmid pSM19035 wereobtained using the vapor diffusion technique with ammonium phosphateas the precipitating agent. The crystals diffracted X-raysto a maximum resolution of 2.5Å. Due to proteolytic degradationduring the crystallization experiment, the crystals containonly the N-terminal catalytic domain of ß recombinasecorresponding to about 60% of the molecular mass of the initiallyassayed native protein. The proteolytic removal of the C-terminalDNA-binding domain demonstrated that protein modification canbe essential to provide material suitable for X-ray analysis.     

Zur Weiterverwendung der Eisenbahnhochbrücke Hochdonn über den Nord‐Ostsee‐Kanal

Refurbishment of the railway bridge Hochdonn across the Ciel Canal. This paper gives details of the safety and residual life assessments for the railway bridge across the North‐Sea‐Baltic‐Sea‐canal at Hochdonn showing aspect of traffic development, pre‐damages and repair work and braking loads. The study shows that the structure though designed according to old specifications with simple calculation models that are compensated by adequate structural detailing complies basically with modern requirements for serviceability and ultimate limit states including durability if some additional measures are carried out to take modern standard‐developments into account.     

Aufbau,Betriebsverhalten und Regelbarkeit von Dampfstrahl-Vakuumpumpen

For an economical and conservation-minded use of steam jet vacuum pumps it is important to utilize their possibilities regarding control and energy saving. This paper shall give an overview of the possibilities.     

Dynamical behaviour of a friction oscillator with simultaneous self and external excitation

Friction-induced self-sustained oscillations, also known as stick-slip vibrations, occur in mechanical systems as well as in everyday life. In engineering applications these vibrations are undesirable and should be avoided. In the present paper it is shown how the very robust limit cycles of stick-slip vibrations can be broken up by a harmonic disturbance. Based on a simple model of a friction oscillator with simultaneous self and external excitation the resulting bifurcation behaviour and the routes to chaos are investigated for a wide range of system parameters. The influence of different types of friction characteristics is elaborated and the admissibility of smoothing procedures is examined by comparing results gained for non-smooth and smoothed friction characteristics.     

Measurement of reasons for resignation of professionals: Questionnaire versus company and consultant exit interviews.

3 different information sources of reasons for voluntary resignation of several hundred professional employees in a large manufacturing company were evaluated: (a) exit interviews conducted by company management, (b) follow-up attitude questionnaires mailed from the company's personnel department, and (c) exit interviews by an outside consultant. Over 3 successive years, the distribution of reasons for termination derived from management exit interviews did not correlate significantly with data from the follow-up mail questionnaire. For 37 Ss there were significant differences between exit intreviews by management vs repeat interviews of the same individuals by the outside consultant (p     

Characterization of aerobic spore-forming bacteria associated with industrial dairy processing environments and product spoilage

Due to changes in the design of industrial food processing and increasing international trade, highly thermoresistant spore-forming bacteria are an emerging problem in food production. Minimally processed foods and products with extended shelf life, such as milk products, are at special risk for contamination and subsequent product damages, but information about origin and food quality related properties of highly heat-resistant spore-formers is still limited. Therefore, the aim of this study was to determine the biodiversity, heat resistance, and food quality and safety affecting characteristics of aerobic spore-formers in the dairy sector. Thus, a comprehensive panel of strains (n = 467), which originated from dairy processing environments, raw materials and processed foods, was compiled. The set included isolates associated with recent food spoilage cases and product damages as well as isolates not linked to product spoilage. Identification of the isolates by means of Fourier-transform infrared spectroscopy and molecular methods revealed a large biodiversity of spore-formers, especially among the spoilage associated isolates. These could be assigned to 43 species, representing 11 genera, with Bacillus cereus s.l. and Bacillus licheniformis being predominant. A screening for isolates forming thermoresistant spores (TRS, surviving 100 °C, 20 min) showed that about one third of the tested spore-formers was heat-resistant, with Bacillus subtilis and Geobacillus stearothermophilus being the prevalent species. Strains producing highly thermoresistant spores (HTRS, surviving 125 °C, 30 min) were found among mesophilic as well as among thermophilic species. B. subtilis and Bacillus amyloliquefaciens were dominating the group of mesophilic HTRS, while Bacillus smithii and Geobacillus pallidus were dominating the group of thermophilic HTRS. Analysis of spoilage-related enzymes of the TRS isolates showed that mesophilic strains, belonging to the B. subtilis and B. cereus groups, were strongly proteolytic, whereas thermophilic strains displayed generally a low enzymatic activity and thus spoilage potential. Cytotoxicity was only detected in B. cereus, suggesting that the risk of food poisoning by aerobic, thermoresistant spore-formers outside of the B. cereus group is rather low.     

Topology-based kernels with application to inference problems in Alzheimer's disease

Alzheimer's disease (AD) research has recently witnessed a great deal of activity focused on developing new statistical learning tools for automated inference using imaging data. The workhorse for many of these techniques is the support vector machine (SVM) framework (or more generally kernel-based methods). Most of these require, as a first step, specification of a kernel matrix K between input examples (i.e., images). The inner product between images I(i) and I(j) in a feature space can generally be written in closed form and so it is convenient to treat K as "given." However, in certain neuroimaging applications such an assumption becomes problematic. As an example, it is rather challenging to provide a scalar measure of similarity between two instances of highly attributed data such as cortical thickness measures on cortical surfaces. Note that cortical thickness is known to be discriminative for neurological disorders, so leveraging such information in an inference framework, especially within a multi-modal method, is potentially advantageous. But despite being clinically meaningful, relatively few works have successfully exploited this measure for classification or regression. Motivated by these applications, our paper presents novel techniques to compute similarity matrices for such topologically-based attributed data. Our ideas leverage recent developments to characterize signals (e.g., cortical thickness) motivated by the persistence of their topological features, leading to a scheme for simple constructions of kernel matrices. As a proof of principle, on a dataset of 356 subjects from the Alzheimer's Disease Neuroimaging Initiative study, we report good performance on several statistical inference tasks without any feature selection, dimensionality reduction, or parameter tuning.