Studies on Cyclotella meneghiniana Kutz III. The frustule

This article does not have an abstract

On Camptylonema indicum Schmidle and Camptylonemops is gen. nov.

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Electron microscopy and algology

Since 1936, when the first alga was investigated with the help of the Electron Microscope more and more algae have been studied. These studies have greatly contributed to our knowledge of the submicroscopic morphology of algae. A review of the most important aspects of these investigations is given in this paper. The utilization of the results of these Electron Microscopic investigations in taxonomy is discussed

Taenioma J. Ag. from India

Both the known species of Taenioma, T. perpusillum J. Ag. and T. nanum (Kuetz.) Papenfuss, are here reported for the first time from India. General features of thallus organisation in both species are described in detail. The development of tetrasporangia in T.Perpusillum is described. In general, the writers' observations are in agreement with those of Papenfuss. The taxonomy of the genus is discussed and the authors agree with Papenfuss in keeping the two species distinct

Mastigocladopsis jogensis gen. et sp. nov., a new member of the stigonemataceae

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On the Period-Luminosity-Colour-Metallicity relation and the pulsational characteristics of lambda Bootis type stars

The group of lambda Bootis type stars comprises late B- to early F-type, Population I objects which are basically metal weak, in particular the Fe group elements, but with the clear exception of C, N, O and S. The present work is a continuation of the studies by Paunzen et al. (1998, A&A, 335, 533), who presented first results on the pulsational characteristics of the lambda Bootis stars. Since then, we have observed 22 additional objects; we found eight new pulsators and confirmed another one. Furthermore, new spectroscopic data (Paunzen, 2001, A&A, 373, 633) allowed us to sort out misidentified candidates and to add true members to the group. From 67 members of this group, only two are not photometrically investigated yet which makes our analysis highly representative. We have compared our results on the pulsational behaviour of the lambda Bootis stars with those of a sample of delta Scuti type objects. We find that at least 70% of all lambda Bootis type stars inside the classical instability strip pulsate, and they do so with high overtone modes (Q < 0.020d). Only a few stars, if any, pulsate in the fundamental mode. Compared to the delta Scuti stars, the cool and hot borders of the instability strip of the lambda Bootis stars are shifted by about 25mmag, towards smaller (b-y)0. Using published abundances and the metallicity sensitive indices of the Geneva 7-colour and Stroemgren uvbybeta systems, we have derived [Z] values which describe the surface abundance of the heavier elements for the group members. We find that the Period-Luminosity-Colour relation for the group of lambda Bootis stars is within the errors identical with that of the normal delta Scuti stars. No clear evidence for a statistically significant metallicity term was detected.Comment: 14 pages, 8 figures, accepted by A&