Ein (M,F)-Problem

Summary The proof of the problem which was studied in a former work, was now brought to an end: that among all convex rotatory bodies of the constant lengthsl the cones possess the smallest surfaces ifM is given.     

Neue Extremalprobleme über konvexe Rotationskörper

Summary It is shown in this note that every sufficiently elongated conic frustum assumes, if radius of equatorr, lengthl and volumeV of a convex body of revolution are given, largest surfaceF as well as largest integral of mean curvatureM. The conic frustum is the only extremal body. For smalll, the situation is intricated and has not yet been clarified.     

Ein (M,F)-Problem mit Nebenbedingungen

Summary In a former publication, the problem could only be solved under two restrictions. Proof is now given that the cones are extremal in the whole of class I.     

Further observations on the effects of selenium and antioxidants on exudative diathesis in chicks

Zusammenfassung Bei Fütterung von Küken mit einer Vitamin-E-freien Nahrung unter Zugabe von 0,1–1 ppm Selen in der ersten Woche wurde das Auftreten exsudativer Diathese 2–7 Tage hinausgeschoben. Es wird deshalb angenommen, dass die biologisch aktive Verbindung von Selen nur geringfügig deponiert wird.Die von amerikanischen Forschern gefundene Schutzwirkung von Ethoxyquin gegen exsudative Diathese wird bestätigt.

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Fulbright Research Scholar 1959–1960.     

Über das Hauptproblem bei konvexen Rotationskörpern

Summary It is shown that over the distance 0X8/² in the diagram, there is a region which is free from picture points («Bildpunkten») of the convex rotation bodies. This assertion is based on two different groupings of the convex rotation bodies into troops, namely at constant lengthl and constant radius of the equatorr, and at constantl and constant length of the resulting meridial curveL. From this, new relations like between the measurements of the convex rotation bodies follow.     

Die symmetrische Kugelzone als extremaler Rotationskörper

Summary For a convex body in three dimensions letV be the volume,F the surface area, andM the total mean curvature.TheBrunn-Minkowski theory gives the following well-known result: Among all the convex bodies withV andF fixed the spherical cap-body gives the maximum ofM.—The question regarding the minimum ofM has not yet been solved for the general case.—The authors prove that the minimum ofM is given by the symmetrical spherical zone, if we restrict our investigation to bodies of revolution.     

Comparison of genome degradation in Paratyphi A and Typhi, human-restricted serovars of Salmonella enterica that cause typhoid

Salmonella enterica serovars often have a broad host range, and some cause both gastrointestinal and systemic disease. But the serovars Paratyphi A and Typhi are restricted to humans and cause only systemic disease. It has been estimated that Typhi arose in the last few thousand years. The sequence and microarray analysis of the Paratyphi A genome indicates that it is similar to the Typhi genome but suggests that it has a more recent evolutionary origin. Both genomes have independently accumulated many pseudogenes among their approximately 4,400 protein coding sequences: 173 in Paratyphi A and approximately 210 in Typhi. The recent convergence of these two similar genomes on a similar phenotype is subtly reflected in their genotypes: only 30 genes are degraded in both serovars. Nevertheless, these 30 genes include three known to be important in gastroenteritis, which does not occur in these serovars, and four for Salmonella-translocated effectors, which are normally secreted into host cells to subvert host functions. Loss of function also occurs by mutation in different genes in the same pathway (e.g., in chemotaxis and in the production of fimbriae).     

The ageing systemic milieu negatively regulates neurogenesis and cognitive function

In the central nervous system, ageing results in a precipitous decline in adult neural stem/progenitor cells and neurogenesis, with concomitant impairments in cognitive functions. Interestingly, such impairments can be ameliorated through systemic perturbations such as exercise. Here, using heterochronic parabiosis we show that blood-borne factors present in the systemic milieu can inhibit or promote adult neurogenesis in an age-dependent fashion in mice. Accordingly, exposing a young mouse to an old systemic environment or to plasma from old mice decreased synaptic plasticity, and impaired contextual fear conditioning and spatial learning and memory. We identify chemokines--including CCL11 (also known as eotaxin)--the plasma levels of which correlate with reduced neurogenesis in heterochronic parabionts and aged mice, and the levels of which are increased in the plasma and cerebrospinal fluid of healthy ageing humans. Lastly, increasing peripheral CCL11 chemokine levels in vivo in young mice decreased adult neurogenesis and impaired learning and memory. Together our data indicate that the decline in neurogenesis and cognitive impairments observed during ageing can be in part attributed to changes in blood-borne factors.