Beziehung zwischen Xanthindehydrase und Oxydations-geschmack von Milch

Zusammenfassung Die Rolle der Xanthindehydrase bei der Entstehung des Oxydationsgeschmakkes in Milch ist umstritten. Bei Versuchen über die Oxydation von Xanthin und Adenin in Gegenwart dieses Enzyms wurde durch Zusatz einer Linolsäureemulsion eine Erhöhung der Reaktionsgeschwindigkeit festgestellt. Angeregt durch diese Beobachtungen wird ein möglicher Einfluß der durch die Xanthindehydrase katalysierten Reaktionen auf die Entstehung des Geschmacksfehlers in Milch diskutiert.Auszug aus der Dissertation vonEberhard Grassmann: Zur Oxydation von Xanthin und anderen Purinen in Milch durch Xanthindehydrase. Technische Hochschule München 1966.     

Impairment of energy metabolism in intact residual myocardium of rat hearts with chronic myocardial infarction

The purpose of this study was to test the hypothesis that energy metabolism is impaired in residual intact myocardium of chronically infarcted rat heart, contributing to contractile dysfunction. Myocardial infarction (MI) was induced in rats by coronary artery ligation. Hearts were isolated 8 wk later and buffer-perfused isovolumically. MI hearts showed reduced left ventricular developed pressure, but oxygen consumption was unchanged. High-energy phosphate contents were measured chemically and by 31P-NMR spectroscopy. In residual intact left ventricular tissue, ATP was unchanged after MI, while creatine phosphate was reduced by 31%. Total creatine kinase (CK) activity was reduced by 17%, the fetal CK isoenzymes BB and MB increased, while the "adult" mitochondrial CK isoenzyme activity decreased by 44%. Total creatine content decreased by 35%. Phosphoryl exchange between ATP and creatine phosphate, measured by 31P-NMR magnetization transfer, fell by 50% in MI hearts. Thus, energy reserve is substantially impaired in residual intact myocardium of chronically infarcted rats. Because phosphoryl exchange was still five times higher than ATP synthesis rates calculated from oxygen consumption, phosphoryl transfer via CK may not limit baseline contractile performance 2 mo after MI. In contrast, when MI hearts were subjected to acute stress (hypoxia), mechanical recovery during reoxygenation was impaired, suggesting that reduced energy reserve contributes to increased susceptibility of MI hearts to acute metabolic stress.     

Rheological investigation of form relaxation and interface relaxation processes in polymer blends

Summary Transmission electron microscopical and rheological investigations have been performed on polymer blend systems of the type A/B, A/A-b-B/B, and A/C-b-B/B, where B is poly(methyl methacrylate) as the continuous and A is polystyrene as the dispersed phase. A-b-B is the corresponding diblock copolymer, and C-b-B is a diblock copolymer with poly(cyclohexyl methacrylate) (C) being thermodynamically miscible with A. The sphere-size distribution was estimated from the TEM data and found to be monomodal for all blends. Smaller sphere sizes in the A/C-b-B/B blends compared with the A/A-b-B/B blends prove the efficiency of the enthalpic acting compatibilizer.The rheological material functions G and G were used to calculate relaxation time spectra and to determine characteristic relaxation times. The form relaxation time ₁ for the relaxation of the ellipsoidally deformed soft PS-particles back to spheres have been verified for all blends no matter whether they where compatibilized or not. An additional relaxation time was found for both types of compatibilized blends. This time is assigned to a non-isotropic interfacial stress, which may arise from relaxation processes of the block copolymers at the interface.     

On stateless deterministic restarting automata

The transitions of a stateless automaton do not depend on internal states but solely on the symbols currently scanned by its head accessing the input and memory. We investigate stateless deterministic restarting automata that, after executing a rewrite step, continue to read their tape before performing a restart. Even the weakest class thus obtained contains the regular languages properly. The relations between different classes of stateless automata as well as between stateless automata and the corresponding types of automata with states are investigated, and it is shown that the language classes defined by the various types of deterministic stateless restarting automata without auxiliary symbols are anti-AFLs that are not even closed under reversal.     

Deterministic pushdown-CD-systems of stateless deterministic R(1)-automata

Recently the one-counter trace languages and the context-free trace languages have been characterized through restricted types of cooperating distributed systems (CD-systems) of stateless deterministic restarting automata with window size one (so-called stl-det-R(1)-automata) that work in mode ‘=1’ and that use an external counter or pushdown store to determine the successor components within computations. Here we study the deterministic variants of these CD-systems, comparing the resulting language classes to the classes of languages defined by CD-systems of stl-det-R(1)-automata without such an external device and to some classical language families, among them in particular the classes of rational, one-counter, and context-free trace languages. In addition, we present a large number of (non-)closure properties for our language classes.     

Fast computation of close-coupling exchange integrals using polynomials in a tree representation

The semi-classical atomic-orbital close-coupling method is a well-known approach for the calculation of cross sections in ion–atom collisions. It strongly relies on the fast and stable computation of exchange integrals. We present an upgrade to earlier implementations of the Fourier-transform method.For this purpose, we implement an extensive library for symbolic storage of polynomials, relying on sophisticated tree structures to allow fast manipulation and numerically stable evaluation. Using this library, we considerably speed up creation and computation of exchange integrals. This enables us to compute cross sections for more complex collision systems.

Program summary

Program title: TXINTCatalogue identifier: AEHS_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEHS_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 12 332No. of bytes in distributed program, including test data, etc.: 157 086Distribution format: tar.gzProgramming language: Fortran 95Computer: All with a Fortran 95 compilerOperating system: All with a Fortran 95 compilerRAM: Depends heavily on input, usually less than 100 MiBClassification: 16.10Nature of problem: Analytical calculation of one- and two-center exchange matrix elements for the close-coupling method in the impact parameter model.Solution method: Similar to the code of Hansen and Dubois [1], we use the Fourier-transform method suggested by Shakeshaft [2] to compute the integrals. However, we heavily speed up the calculation using a library for symbolic manipulation of polynomials.Restrictions: We restrict ourselves to a defined collision system in the impact parameter model.Unusual features: A library for symbolic manipulation of polynomials, where polynomials are stored in a space-saving left-child right-sibling binary tree. This provides stable numerical evaluation and fast mutation while maintaining full compatibility with the original code.Additional comments: This program makes heavy use of the new features provided by the Fortran 90 standard, most prominently pointers, derived types and allocatable structures and a small portion of Fortran 95. Only newer compilers support these features. Following compilers support all features needed by the program.

• • 

  GNU Fortran Compiler “gfortran” from version 4.3.0

• • 

  GNU Fortran 95 Compiler “g95” from version 4.2.0

• • 

  Intel Fortran Compiler “ifort” from version 11.0

Running time: Heavily dependent on input, usually less than one CPU second.References:

• [1] 

  J.-P. Hansen, A. Dubois, Comput. Phys. Commun. 67 (1992) 456.

• [2] 

  R. Shakeshaft, J. Phys. B: At. Mol. Opt. Phys. 8 (1975) L134.

     

Illustration of fairness in evolutionary multi-objective optimization

It is widely assumed that evolutionary algorithms for multi-objective optimization problems should use certain mechanisms to achieve a good spread over the Pareto front. In this paper, we examine such mechanisms from a theoretical point of view and analyze simple algorithms incorporating the concept of fairness. This mechanism tries to balance the number of offspring of all individuals in the current population. We rigorously analyze the runtime behavior of different fairness mechanisms and present illustrative examples to point out situations, where the right mechanism can speed up the optimization process significantly. We also indicate drawbacks for the use of fairness by presenting instances, where the optimization process is slowed down drastically.