Weak Factorizations,Fractions and Homotopies

We show that the homotopy category can be assigned to any category equipped with a weak factorization system. A classical example of this construction is the stable category of modules. We discuss a connection with the open map approach to bisimulations proposed by Joyal, Nielsen and Winskel. Mathematics Subject Classifications (2000) 18A99, 55P10, 68Q85.JiÍ Rosický: Supported by the Grant Agency of the Czech Republic under the grant 201/02/0148.     

Synthesis and experimental study of through-space hydrogen-fluorine and carbon-fluorine spin-spin coupling in 4,5-substituted 1-acetyl-8-fluoronaphthalenes

The synthesis and NMR study (1H, 13C, and 19F) of a complete series of 4,5-substituted 1-acetyl-8-fluoronaphthalenes are reported. This data revealed a 6J(H,F) and a 5J(C,F) through space coupling between the fluorine and the methyl on the acetyl group (1H and 13C). The magnitude of this coupling constant changes depending on the nature of the substituent at C-4, the internuclear distance, and the solvent.     

Untersuchungen zur Bindungsspezifit?t viraler und bakterieller Sialidasen. Eine neuartige Anwendung der 1H-NMR-Spektroskopie

Ohne Zusammenfassung

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Investigations on the binding specificity of viral and bacterial sialidases. A novel application of ¹H-NMR-spectroscopy

     

Alkaloid Production in Catharanthus Roseus Cell Cultures. XI. Biotransformation of 3′, 4′-Anhydrovinblastine to Other Bisindole Alkaloids

Biotransformation studies of 3′,4′-anhydrovinblastine (1) in Calharanthus roseus cell suspension cultures are reported. A detailed study of one cell line, coded at ?916”?, has revealed that 1 is transformed to the natural bisindole alkaloids leurosine ( 2 ) and Catharine ( 3 ) in approximately 25–30 and 9–16% yield, respectively. In 24–48 h, about 40% of 1 is utilized by the cells. Conditions for biotransformation of 1 have not been optimized so the above yields quoted are not final.     

Power and Taxes in a multi-commodity economy

Taxation and redistribution in a democratic majority-rule society are analyzed, using the Harsanyi-Shapley non-transferable utility value. The context is that of a multi-commodity pure exchange economy. Two approaches are treated: one in which taxes are in kind and exchange takes the form of barter; and one in which taxes are in money, exchange takes the form of sale and purchase, and prices are determined by a process of supply and demand. It is shown that in the presence of a non-atomic continuum of agents, the two approaches are equivalent, but that this is not so when there are only finitely many agents. It is also shown that the value exists under both approaches, and a characterization is found in the non-atomic case. This work was supported by U.S. National Science Foundation Grant SOC74-11446 at the Institute for Mathematical Studies in the Social Sciences, Stanford University, and by a grant from the Israel National Council for Research and Development at the Hebrew University of Jerusalem.