Internal audits in private medical laboratory practice – a Finnish experience in 1996–2000

Internal audits inherently effect quality improvement, and concrete results can be expected by careful planning. As audits should improve the quality system in situ, the development of audits should not be neglected. ISO/IEC 17025 describes the objectives of internal audits and management reviews in more detail compared to the former standards EN 45001 and ISO/IEC Guide 25, although the main features are unchanged. This addresses continuous surveillance of the current practice. A brief questionnaire on vertical audits was distributed to 74 of 120 employees at a Finnish private medical laboratory, Medix Laboratories Ltd. A positive feed-back was received from the current management of audits. However, the study revealed that continuous supervision of audits is needed. Many employees were not willing to perform audits if they had no previous experience. Additionally, audits performed at the workbench were not considered as the best possible for fruitful discussions. Received: 20 February 2001 Accepted: 30 November 2001     

Decrease in activity caused by hydrogen in Ziegler-Natta ethene polymerisation

In this study we prepared seven different Ziegler-Natta catalysts and polymerised them at different hydrogen concentrations in order to investigate their kinetic behaviour during polymerisation. The objective was to see whether the results corresponded to what could be expected on the basis of Kissin's β-agostic deactivation theory. According to this theory, hydrogen causes the formation of dormant sites due to the formation of β-agostic coordination from the ethyl groups formed after hydrogen termination. According to this theory, the more hydrogen that is used, the more β-agostic coupling and the smaller percentage of Ti in a polymerising state. This β-agostic coupling would thus explain the lower activity level seen in polymerisation where more hydrogen has been used.The results of this study showed that none of the catalysts showed the kind of behaviour that would correspond to what could be predicted on the basis of Kissin's theory. Deactivation could be detected only when a lower amount of hydrogen was used. When higher amounts of hydrogen were used in polymerisation there was a clear delay in activation time of the catalysts. This particularly seemed to be the case for catalysts where Ti was present as Ti(IV). This delay in the activation of the catalyst caused a decrease in activity in addition to the normal decrease in activity due to hydrogen replacing C₂^′′ in the polymerisation process.The only catalyst showing no delay in activation was a silica-based PE ZN catalyst where the Ti was already in trivalent form. In this case no decrease in activity was observed in addition to the normal decrease in activity caused by hydrogen replacing C₂^′′ in the polymerisation process.     

Multiple polypeptide forms observed in two-dimensional gels of Methylococcus capsulatus (Bath) polypeptides are generated during the separation procedure

We have examined two-dimensional electrophoresis (2-DE) gel maps of polypeptides from the Gram-negative bacterium Methylococcus capsulatus (Bath) and found the same widespread trains of spots as often reported in 2-DE gels of polypeptides of other Gram-negative bacteria. Some of the trains of polypeptides, both from the outer membrane and soluble protein fraction, were shown to be generated during the separation procedure of 2-DE, and not by covalent post-translational modifications. The trains were found to be regenerated when rerunning individual polypeptide spots. The polypeptides analysed giving this type of trains were all found to be classified as stable polypeptides according to the instability index of Guruprasad et al. (Protein Eng. 1990, 4, 155-161). The phenomenon most likely reflects conformational equilibria of polypeptides arising from the experimental conditions used, and is a clear drawback of the standard 2-DE procedure, making the gel picture unnecessarily complex to analyse.     

Stress-Induced Domain Wall Motion in a Ferroelastic Mn3+ Spin Crossover Complex

Domain wall motion is detected for the first time during the transition to a ferroelastic and spin state ordered phase of a spin crossover complex. Single-crystal X-ray diffraction and resonant ultrasound spectroscopy (RUS) revealed two distinct symmetry-breaking phase transitions in the mononuclear Mn³⁺ compound [Mn(3,5-diBr-sal₂(323))]BPh₄, 1. The first at 250 K, involves the space group change Cc→Pc and is thermodynamically continuous, while the second, Pc→P1 at 85 K, is discontinuous and related to spin crossover and spin state ordering. Stress-induced domain wall mobility was interpreted on the basis of a steep increase in acoustic loss immediately below the the Pc-P1 transition     

A relaxation scheme for conservation laws with a discontinuous coefficient

We study a relaxation scheme of the Jin and Xin type for conservation laws with a flux function that depends discontinuously on the spatial location through a coefficient . If , we show that the relaxation scheme produces a sequence of approximate solutions that converge to a weak solution. The Murat-Tartar compensated compactness method is used to establish convergence. We present numerical experiments with the relaxation scheme, and comparisons are made with a front tracking scheme based on an exact Riemann solver.     

Continuous dependence estimates for viscosity solutions of integro-PDEs

We present a general framework for deriving continuous dependence estimates for, possibly polynomially growing, viscosity solutions of fully nonlinear degenerate parabolic integro-PDEs. We use this framework to provide explicit estimates for the continuous dependence on the coefficients and the “Lévy measure” in the Bellman/Isaacs integro-PDEs arising in stochastic control/differential games. Moreover, these explicit estimates are used to prove regularity results and rates of convergence for some singular perturbation problems. Finally, we illustrate our results on some integro-PDEs arising when attempting to price European/American options in an incomplete stock market driven by a geometric Lévy process. Many of the results obtained herein are new even in the convex case where stochastic control theory provides an alternative to our pure PDE methods.     

A Theory of <Emphasis Type="Italic">L</Emphasis><Superscript>1</Superscript>-Dissipative Solvers for Scalar Conservation Laws with Discontinuous Flux

We propose a general framework for the study of L ¹ contractive semigroups of solutions to conservation laws with discontinuous flux:

The discontinuous Galerkin method for fractional degenerate convection-diffusion equations

We propose and study discontinuous Galerkin methods for strongly degenerate convection-diffusion equations perturbed by a fractional diffusion (Lévy) operator. We prove various stability estimates along with convergence results toward properly defined (entropy) solutions of linear and nonlinear equations. Finally, the qualitative behavior of solutions of such equations are illustrated through numerical experiments.