Chromatography of the Lipide Bases on Paper Impregnated with Silicic Acid

Chromatography of various long-chain aliph a tic a - amino alcoh ols, a-amino ketones and a-diamines containing . 18 and 20 carbon atoms on paper impregnated with silicic acid is described. Most of these compounds - which· are listed in Table I - are of biological importance

On the erythro and threo-2,3-Dihydroxytetracosanoic Acids

The erythro and threo-2,3-dihydroxytetracosanoic acids have been prepared by hydroxylation of trans-2-tetracosenoic acid (I) with both peracetic acid and potassium permanganate. A procedure for the preparation of trans-2-tetracoselioic acid (I) is also described

Chromatography of the Lipide Bases on Paper Impregnated with Silicic Acid

Chromatography of various long-chain aliph a tic a - amino alcoh ols, a-amino ketones and a-diamines containing . 18 and 20 carbon atoms on paper impregnated with silicic acid is described. Most of these compounds - which· are listed in Table I - are of biological importance

A new glycolipid sulfate ester in Halobacterium cutirubrum

NRC publication: Ye

Observational learning of two visual discriminations by pigeons: a within-subjects design.

Pigeon's observational learning of successive visual discrimination was studied using within-subject comparisons of data from three experimental conditions. Two pairs of discriminative stimuli were used; each bird was exposed to two of the three experimental conditions, with different pairs of stimuli used in a given bird's two conditions. In one condition, observers were exposed to visual discriminative stimuli only. In a second condition, subjects were exposed to a randomly alternating sequence of two stimuli where the one that would subsequently be used as S+ was paired with the operation of the grain magazine. In a third experimental condition, subjects were exposed to the performance of a conspecific in the operant discrimination procedure. After exposures to conspecific performances, there was facilitation of discriminative learning, relative to that which followed exposures to stimulus and reinforcement sequences or exposures to stimulus sequences alone. Exposure to stimulus and food-delivery sequences enhanced performance relative to exposure to stimulus sequences alone. The differential effects of these three types of exposure were not attributable to order effects or to task difficulty; rather, they clearly were due to the type of exposure