and Summary This study concerns the acoustic behaviour of the bush cricket Tettigonia cantans Fuess. (Orthoptera: Tettigoniidae). Natural habitats with different population densities of stable singers have been selected. The dispersion patterns of singing males and the sound levels neighbouring insects receive from each other were investigated. The behavioural patterns of an established male elicited by the song of a conspecific were analysed and related to the population densities of constant singers in their biotope. The competition between males and its possible effect on female behaviour have been discussed. Constantly singing males clump in areas with dense vegetation and within these clumps they are regularly spaced. Males seem to space themselves according to the song intensities (72–87 dB SPL) they receive from each other. Between close neighbours rivalry behaviour is expressed either by males producing alternating songs, or in an approach towards a constantly singing insect, or in an aggressive encounter. Of these three behaviour patterns aggressive encounters are most common in high‐density populations. Rivalry does not influence the dispersion pattern of the males. A hypothesis is inferred from observations on female behaviour that rivalry itself constitutes an attractive stimulus for females. Zusammenfassung Rivalenverhalten und Verteilung konstant singender Männchen der Laubheuschrecke Tettigonia cantans sind im Freiland untersucht worden. Dazu wurden unterschiedlich dichte Populationen gewählt. Konstant singende Männchen treten in Arealen mit dichter Vegetation gehäuft auf, sind aber innerhalb soldier Ansammlungen regelmäßig verteilt. Offenbar verteilen sich die Männchen nach gleichen Schalldruckpegeln (72–87 dB) im Gesang der Nachbarn. Das Rivalenverhalten kann in abwechselndem Singen eng benachbarter Männchen bestehen, in bloßer Annäherung an einen konstanten Sänger oder kann eine aggressive Begegnung einschließen. Besonders in dichten Populationen kennzeichnen agonistische Kontakte das Rivalenverhalten. Das Rivalenverhalten beeinträchtigt jedoch nicht das regelmäßige Verteilungsmuster der Männchen. Beobachtungen an Weibchen lassen vermuten, daß das Rivalenverhalten selbst einen stimulierenden Einfluß auf Phonotaxis und Auswahlverhalten der Weibchen ausübt.
We discuss test methods and results for determining individual clay platelets shape, size, size distribution, elemental composition, and impurities. Commercial sodium salt varieties of natural, semisynthetic and synthetic clay (Cloisite®‐Na+, Somasif ME‐100, and Topy‐Na+, respectively) were analyzed. In this international collaboration, eight laboratories on three continents carried out the work within the VAMAS TWA‐33 activities. There are large differences between the three nanofillers as far as: (1) the platelet orthogonal dimensions, (2) chemical composition, and (3) contaminants (their diversity and quantity) are concerned. Elaborate purification of natural clays leaves behind 2–5 wt% of organic and mineral impurities, whose nature, shape, size, and chemistry depend on the clay origin. These contaminants affect nanocomposite performance, thus controlling their composition and quantity is essential. The article describes the developed methods, summarizes the preliminary results, discusses the encountered difficulties, and proposes methods for solving them. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
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Tenses crop up in two ways in this issue, both inspired by readers' letters. The first referred to the use of the present perfect on both sides of the Atlantic, and DAVID CRYSTAL looks at that. The second is the puzzling ‘plupluperfect’, and VALERIE LAMBERT, BILL BROUGHTON and FRANK PALMER look at that.
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