Jan P. Radomski

An empirical relationship between the eluant strength parameter ε° and solvent lewis acidity and basicity

Abstract It has been found that Snyders eluant strength parameter e°, used in liquid-solid adsorption chromatography, can be well described by a complementary Lewis acid-base model for solute-solvent interactions: e°=0.152+0.859 · E N T + 0.332 · B KT ( cf Eq.9 ), with a correlation coefficient of r = 0.949 for 28 solvents. This result is in agreement with the theoretical interpretation of e° The correct statistical procedure for estimating the significance of added explanatory parameters in the sequential multiparameter regression analysis is shown ( cf Appendix). A comprehensive list of improved Kamlet-Taft solvent basicity parameters, B KT , is given.

Thiazolidine-4(R)-carboxylic acids derived from sugars: Part I, C-2-epimerisation in aqueous solutions

Abstract Reactions of l -cysteine ( 1 ) with l -xylose, d -ribose, d -lyxose, d -arabinose, d -glucose, l -rhamnose, and l -fucose in aqueous ethanol yielded crystalline 2( S )-(polyhydroxyalkyl)thiazolidine-4( R )-carboxylic acids. Likewise, glycolaldehyde and l -glyceraldehyde, d -xylose, l -arabinose, d -mannose, d -galactose, and d -fucose gave crystalline 2( R ),4( R ) epimers. The reaction of 1 and d -glyceraldehyde gave a syrupy mixture of 2( S ),4( R ) and 2( R ),4( R ) compounds. The same substrates, but with no ethanol present, gave the 2( S ),4( R ) epimers for glycolaldehyde, l -xylose, l -fucose, and l -arabinose, and the 2( R ),4( R ) epimers for d -lyxose, l -rhamnose, d -mannose, d -galactose, and d -fucose. The reactions of d -ribose, d -arabinose, d -xylose, and d -glucose gave syrupy mixtures of epimers. The crystalline reaction products, when dissolved in water, undergo rapid epimerisation as reflected by mutarotation and changes in the 1 H- and 13 C-n.m.r. spectra.

Social effects in simple computer model of aging

A simple evolutionary model for biological aging is modified such that it requires a minimum population for survival, like in human society. This social effect leads to a transition between extinction and survival of the species.

Brief Communication: A model of influenza virus spread as a function of temperature and humidity

The influence that atmospheric conditions might have on the efficiency of the spread of influenza virus is important for epidemiological and evolutionary research. However, it has not been satisfactorily recognized and quantified so far. Here we provide a statistical model of influenza transmission between individuals. It has been derived from the results of recent experiments, which involved infecting guinea pigs with influenza at various temperatures and relative air humidity levels. The wide range of transmission rates in those experiments reflects the ensemble-independent phenomena. The correlation between most of our simulations and the experimental results is satisfactory. For several different conditions, we obtained transmissibility values which seem to be sufficiently accurate to provide partial input for an intended large-scale epidemiological study in the near future.

Brief Communication: Probabilistic model of influenza virus transmissibility at various temperature and humidity conditions

The spread efficiency of influenza virus is significantly affected by several environmental parameters. However, neither the underlying reasons, nor the exact character and magnitude of the phenomena involved are sufficiently well understood. Here we present a probabilistic approach to the virus transmission events. For a sample ensemble, we construct a model of the infectivity as a function of the ambient conditions, and we determine its parameter values on the basis of the available experimental data.

The effect of 2-substituted thiazolidine-4(R)-carboxylic acids on non-protein sulphydryl levels and sulphurtransferase activities in mouse liver and brain

2-Substituted thiazolidine-4(R)-carboxylic acids (TD) were found to increase the concentration of non-protein sulphydryls (NPSH) and the activity of rhodanese (thiosulphate sulphurtransferase, EC 2.8.1.1) and 3-mercaptopyruvate sulphurtransferase (EC 2.8.1.2) in mouse liver. These properties suggest TDs are potentially hepatoprotective compounds. However TDs also cause depletion of NPSH in the mouse brain and this may be the reason for their toxic side effects on the central nervous system.

A Formal Model of Genomic Dna Multiplication and Amplification

We investigate a Markov chain model of genomic DNA duplication from the point of view of stability of its behavior. The duplication can occur either by multiplication, or by amplification. We show that if we also allow additional options for a molecule to pause, or to be removed, then the model is stable for a wide spectrum of parameters. We also show that the model without pause or removal is not stable. A general model which covers both of the above mentioned models is analysed from the point of view of stability.

Scaling in the Donangelo-Sneppen model for evolution of money

The evolution of money from unsuccessful barter attempts, as modeled by Donangelo and Sneppen, is modified by a deterministic instead of a probabilistic selection of the most desired product as money. We check in particular the characteristic times of the model as a function of system size.

SIMULATING THE MITOCHONDRIAL DNA BOTTLENECK

A probabilistic model is proposed with dynamics which naturally leads to a bottleneck in the number of mitochondria transmitted from one host-cell generation to the other. We take into account deleterious mutations during the replication of mitochondria within a cell of a germ-line and introduce selection inside the cell reproduction mechanism. The bottleneck size strongly depends on the selection mechanism and on the maximum number of mitochondria per cell. We obtain that the smaller the maximum allowed number of mitochondria per cell during replication, the tighter the bottleneck. Such a result is in agreement with the fact that species producing small litters provide developing oocytes with a smaller number of mitochondria. This amplifies the differences among oocytes leading to competition and removal of inferior cells.

Chapter 13 - Wavelet Bases for IR Library Compression, Searching and Reconstruction

This chapter discusses wavelet bases for IR library compression, searching, and reconstruction. Most of the commercial databases to date use Fast Fourier Transform (FFT) for spectra compression. The IR spectra show many absorption bands of local character, which makes wavelets well suited for their decomposition. Also, Wavelet Transform is quite faster than FFT. During successful library construction three important factors must be considered— namely, efficient compression algorithm and ratio, fast search speed method, and good spectra reconstruction quality. Fulfillment of all these demands requires some kind of compromise and there are different possible approaches to this problem. Wavelets, well localized in both time and frequency (scale) domains are basis functions ideally suited for description of the unstationary instrumental signals, such as IR or NMR spectra. In addition, signals, such as IR spectra, have in a wavelet domain sparse representation. It means that in wavelet domain there are many wavelet coefficients with small amplitude (absolute value), which can be discarded without loss of essential information carried by a signal. Elimination of small coefficients is equivalent to spectra compression.