Ein Beitrag zur Biosynthese und Physiologie von Kaffein und Trigonellin beiCoffea arabica

Summary Whole young plants were allowed to fix photosynthetically C¹⁴O₂ for 12 hours. The absolute amount and the specific activity of trigonelline, caffeine and glucose in developing and adult leaves were subsequently determined during up to five weeks. There is a rapid incorporation of photosynthetically fixed carbon into trigonelline in both developing and adult leaves. The specific activity of caffeine however increases to any extent only in young developing leaves. It can be concluded that both trigonelline and caffeine are synthesized in leaves ofCoffea arabica. Other problems of the metabolism and translocation of the two substances are discussed.

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Mit 5 Textabbildungen     

Contribution to the mathematical biophysics of automobile driving

Traffic in one direction on a multilane highway is considered, and a general expression for the number of cars which pass a car travelling at a given velocity, as well as the number of cars which the given car passes, is derived for the case when the speeds of different cars are distributed in some arbitrary manner. Closed expressions are derived and discussed for a rectangular distribution. Each passing by another car or of another car is considered as a distracting stimulus which affects the reaction times of the driver. Using previously derived expressions for the safe speed as a function of reaction times, expressions for the safe average speed are derived, in terms of the volume of traffic and of the spread of the distribution of speeds.     

Graphische Darstellung zur Beurteilung von Kartoffelkreuzungen

Ohne ZusammenfassungMit 2 Abbildungen