Rapid method based on reversed-phase high-performance liquid chromatography for purification of human myelin basic protein and its thrombic and endoproteinase Lys-C peptides.

Reversed-phase high-performance liquid chromatography was applied to isolate myelin basic protein from human brain, followed by separation of proteolytic peptides thereof on the same chromatographic system. Brain tissue was delipidated under conditions that keep copurifying proteases inactive. The crude brain protein fraction was applied directly to a C4 column. The homogeneous protein obtained in this way was digested with thrombin and endoproteinase Lys-C in order to produce short defined myelin basic protein peptides. The purified peptides were used to determine the antigen fine specificity of myelin basic protein recognizing T lymphocyte lines isolated from multiple sclerosis patients.     

Families of meromorphic functions avoiding continuous functions

Leth ₁,h ₂ andh ₃ be continuous functions from the unit disk D into the Riemann sphereC such thath _i(z) ≠ h_j(z) (i ≠ j) for eachz∈D. We prove that the setF of all functionsf meromorphic on D such thatf(z)≠h _j (z) for allz ∈ D andj=1,2,3 is a normal family. The result and the method of the proof extend to quasimeromorphic functions in higher dimensions as well. The second author was supported by a Heisenberg fellowship of the DFG. The fourth author was partially supported by the Marsden Fund, New Zealand. This research was completed while the authors were attending a conference at Mathematisches Forschungsinstitut Oberwolfach in Germany. The authors would like to express their sincere thanks to the Institute for providing a stimulating atmosphere and for its kind hospitality.     

On Critical Values of Polynomials with Real Critical Points

Let f be a polynomial of degree at least 2 with f(0)=0 and f′(0)=1. Suppose that all the zeros of f′ are real. We show that there is a zero ζ of f′ such that |f(ζ)/ζ|≤2/3, and that this inequality can be taken to be strict unless f is of the form f(z)=z+cz ³.     

Unbounded domains of normality

Let be a transcendental entire function of order less than 1/2. We introduce the method of ``self-sustaining spread' to study the components of the set of normality of such a function. We give a new proof of the fact that any preperiodic or periodic component of the set of normality of is bounded. We obtain the same conclusion for a wandering domain if the growth rate of is never too small.

     

Julia Sets of Polynomials are Uniformly Perfect

Let f be a polynomial of degree at least two. We shall showthat the Julia set J(f) of f is uniformly perfect. This meansthat there is a constant c(0,1) depending on f only such thatwhenever zJ(f) and 0 < r < diam J(f) then J(f) intersectsthe annulus {w:cr |w — z| r}.     

Separation of aspartate aminotransferase from albumin on substituted agaroses

The affinity of aspartate aminotransferase to its inhibitors coupled to Sepharose 4 B was tested. The affinity was measured as retardation of the enzyme compared to “inert” bovine serum albumin. Carboxylic ligands of citrate and 2-oxoglutarate bound to aminoethyl-Sepharose were the best of those tested in separation of the proteins. Because the ligands were not essentially hydrophobic and because it was shown that ion-exchange is not significant in the elution conditions used, it was suggested that the separation is based on the recognition of substrate or effector by the enzyme.     

On the usage of qualitative reasoning as an approach towards enterprise modelling

This paper analyzes the computational requirements of enterprise modelling, presents a reasoning framework, and reports about a prototype implementation. Enterprise modelling studies complex systems which are normally only partially known, and focuses on studying the qualitative properties of the underlying system, and thus differs from traditional quantitative approaches. Various modelling approaches from computer science and management science are discussed with respect to their suitability for enterprise modelling. Qualitative reasoning is identified as a promising basis to develop a computational framework for enterprise modelling. A rules-constraints-method of reasoning with imprecise knowledge, which is essentially an interval-based version of difference equations, is proposed as a powerful and versatile tool for enterprise modelling. As an illustrative example, a model of a business organization, derived from the concept of a financial statement, is developed and simulated.