Cholesteryl esters in flue-cured tobacco

Zusammenfassung Nach Hydrolyse wurde Cholesterol von einem Sterolester-Bruchteil aus dem «flue-cured» Tabak isoliert und massenspektrometrisch sein Acetat-Derivat einwandfrei festgestellt, obwohl die einzelnen Ester von Cholesterol im Tabak nicht gereinigt oder identifiziert wurden. Zur Isolierung wurden die Zwei-Stufen-Gegenstromverteilung und die Gel-Permeationschromatographie verwendet, 2 brauchbare und wenig aggressive Methoden zur Aufteilung eines komplexen Extraktes in Materialgruppen und nachfolgender gewöhnlicher chromatographischer Bearbeitung.     

Early research on the biological effects of microwave radiation: 1940–1960

Two overriding considerations shaped the development of early research on the biological effects of microwave radiation—possible medical application (diathermy) and uncertainty about the hazards of exposure to radar. Reports in the late 1940s and early 1950s of hazards resulting from microwave exposure led to the near abandonment of medical research related to microwave diathermy at the same time that military and industrial concern over hazards grew, culminating in the massive research effort known as ‘the Tri-Service program’ (1957–1960). Both the early focus on medical application and the later search for hazards played important roles in dictating how this field of research developed as a science.     

The synthesis of a peptide having the structure attributed to a sound habituating material.

A peptide isolated from rats habituated to a sound stimulus has been given the structure (see article) Glu-Ala-Gly-Tyr-Ser-Lys-OH. A synthesis of this compound afforded a product that different from the natural material on the basis of chromatographic and physiological comparisons. The proposed sequence must therefore be in error.     

Minds, machines and economic agents: Cambridge receptions of Boole and Babbage

In the 1860s and 1870s the logic of Boole and the calculating machines of Babbage were key resources in W. S. Jevons’s attempt to construct a mechanical model of the mind, and both therefore played an important role in Jevons’s attempted revolution in economic theory. In this same period both Boole and Babbage were studied within the Cambridge Moral Sciences Tripos, but the Cambridge reading of Boole and Babbage was much more circumspect. Implicitly following the division of the moral sciences into material and ‘real’ as established by the Rev. Grote, John Venn treated Boole’s logic as a purely formal science, while Alfred Marshall based his psychological model of the mechanical part of the human mind upon Babbage’s two-level machine. From the different perspectives of logic and psychology, Venn and Marshall did not simply incorporate their readings of Boole and Babbage, but also attempted to establish the limits to any mechanical explanation of the mind. This comparison of the attitudes to mental science of Jevons and Marshall provides a foundation from which the differing conceptions of economic theory of the two men can be established.     

Effect of growth factors on hepatic drug metabolism in diabetic-hypophysectomized rats

Summary In vivo administration to diabetic-hypophysectomized rats of either the growth factor produced by the plerocercoid larvae of the tapeworm, Spirometra mansonoides, or mammalian growth hormone caused inhibition of hepatic drug metabolism measured in vitro.     

Warming experiments underpredict plant phenological responses to climate change

Warming experiments are increasingly relied on to estimate plant responses to global climate change. For experiments to provide meaningful predictions of future responses, they should reflect the empirical record of responses to temperature variability and recent warming, including advances in the timing of flowering and leafing. We compared phenology (the timing of recurring life history events) in observational studies and warming experiments spanning four continents and 1,634 plant species using a common measure of temperature sensitivity (change in days per degree Celsius). We show that warming experiments underpredict advances in the timing of flowering and leafing by 8.5-fold and 4.0-fold, respectively, compared with long-term observations. For species that were common to both study types, the experimental results did not match the observational data in sign or magnitude. The observational data also showed that species that flower earliest in the spring have the highest temperature sensitivities, but this trend was not reflected in the experimental data. These significant mismatches seem to be unrelated to the study length or to the degree of manipulated warming in experiments. The discrepancy between experiments and observations, however, could arise from complex interactions among multiple drivers in the observational data, or it could arise from remediable artefacts in the experiments that result in lower irradiance and drier soils, thus dampening the phenological responses to manipulated warming. Our results introduce uncertainty into ecosystem models that are informed solely by experiments and suggest that responses to climate change that are predicted using such models should be re-evaluated.