聚苯乙烯负载的奎宁环催化剂的合成及其在Morita-Baylis-Hillman反应中的应用

通过3-(4-乙烯基苄氧基)-1-氮杂-双环[2,2,2]辛烷和苯乙烯共聚合制备聚(苯乙烯-共-3-(4-乙烯基苄氧基)-1-氮杂-双环[2,2,2]辛烷),并将其作为非均相催化剂应用于分子内和分子间的Morita-Baylis-Hillman及氮杂-Morita-Baylis-Hillman反应中,在所有这些反应中,产物的产率都可达到中等水平。     

A Bayesian threshold nonlinearity test for financial time series

We propose in this paper a threshold nonlinearity test for financial time series. Our approach adopts reversible‐jump Markov chain Monte Carlo methods to calculate the posterior probabilities of two competitive models, namely GARCH and threshold GARCH models. Posterior evidence favouring the threshold GARCH model indicates threshold nonlinearity or volatility asymmetry. Simulation experiments demonstrate that our method works very well in distinguishing GARCH and threshold GARCH models. Sensitivity analysis shows that our method is robust to misspecification in error distribution. In the application to 10 market indexes, clear evidence of threshold nonlinearity is discovered and thus supporting volatility asymmetry. Copyright © 2005 John Wiley & Sons, Ltd.     

Alterations in the surface properties of cells responsive to nerve growth factor.

An initial effect of nerve growth factor on a responsive nerve cell line is to increase intracellular cyclic AMP, which in turn leads to a mobilisation of calcium ions. These events are correlated with structural changes in the plasma membrane, increased cell-substratum adhesion, and neurite outgrowth.     

A new compound effective against acute fascioliasis in sheep

Zusammenfassung 2-Acetoxy-4-chlor-3,5-dijodbenzanilid zeigte eine hohe Wirksamkeit gegen junge und gereifteF. hepatica andH. controtus in Schaften bei einer oralen Dosis von 25 und 40 mg/kg. Die gute Verträglichkeit der Verbindung in Schafen ergab sich aus Feldversuchen in Australien.     

Direct estimation of per nucleotide and genomic deleterious mutation rates in Drosophila

Spontaneous mutations are the source of genetic variation required for evolutionary change, and are therefore important for many aspects of evolutionary biology. For example, the divergence between taxa at neutrally evolving sites in the genome is proportional to the per nucleotide mutation rate, u (ref. 1), and this can be used to date speciation events by assuming a molecular clock. The overall rate of occurrence of deleterious mutations in the genome each generation (U) appears in theories of nucleotide divergence and polymorphism, the evolution of sex and recombination, and the evolutionary consequences of inbreeding. However, estimates of U based on changes in allozymes or DNA sequences and fitness traits are discordant. Here we directly estimate u in Drosophila melanogaster by scanning 20 million bases of DNA from three sets of mutation accumulation lines by using denaturing high-performance liquid chromatography. From 37 mutation events that we detected, we obtained a mean estimate for u of 8.4 x 10(-9) per generation. Moreover, we detected significant heterogeneity in u among the three mutation-accumulation-line genotypes. By multiplying u by an estimate of the fraction of mutations that are deleterious in natural populations of Drosophila, we estimate that U is 1.2 per diploid genome. This high rate suggests that selection against deleterious mutations may have a key role in explaining patterns of genetic variation in the genome, and help to maintain recombination and sexual reproduction.     

Subset selection of autoregressive time series models

We propose a solution to select promising subsets of autoregressive time series models for further consideration which follows up on the idea of the stochastic search variable selection procedure in George and McCulloch (1993). It is based on a Bayesian approach which is unconditional on the initial terms. The autoregression stepup is in the form of a hierarchical normal mixture model, where latent variables are used to identify the subset choice. The framework of our procedure is utilized by the Gibbs sampler, a Markov chain Monte Carlo method. The advantage of the method presented is computational: it is an alternative way to search over a potentially large set of possible subsets. The proposed method is illustrated with a simulated data as well as a real data. Copyright © 1999 John Wiley & Sons, Ltd.