On a theory of sandwich construction

The theory of sandwich construction developed in this paper proceeds from the simple assumption that the filling has only transverse direct and shear stiffnesses, corresponding to its functional requirements (§1). This supposition permits integration of the equilibrium equations for the filling (§2). The resulting integrals are used to study the compression buckling of a flat sandwich plate (§3). The formulae obtained are complex, but may be simplified in practical cases (§4). A second approach to sandwich problems is made in §5, where a theory of "bending" of plates is outlined. This generalises the usual theory, making allowance for flexibility in sheer. This approach is applied to overall compression buckling of a plate in §6, and agreement with the previous calculations is found. This suggests the possibility of calculating buckling loads for curved sandwich shells. A simple example, the symmetrical buckling of a circular cylinder in compression is worked out in §7. The theory developed would seem applicable to all cases of buckling of not too short a wave length (§8)

Conservation status of the elegant yellow-black bush-cricket Meruterrana elegans (Orthoptera: Phaneropterinae)—a critically endangered species on Mount Kenya

Two populations of Meruterrana elegans, a monotypic bush-cricket genus, endemic to Mount Kenya in Kenya were surveyed. The species is restricted to Cassipourea forest, a forest community vanishing rapidly on Mount Kenya and with it Meruterrana elegans, which therefore should be included to the IUCN red list of threatened species as Critically Endangered.Keywords: Red list, insects, East Afric

Neuropsychological impairment in children following head injury

There is a high incidence of head injury in children, yet few studies have systematically studied cognitive outcome. This study was designed as a survey to (a) establish the nature of intellectual and neuropsychological deficits that occur after head injuries of differing severity in children aged 6 to 14 years, (b) establish the nature of recovery curves in the first year after injury, and (c) determine which medical and psychosocial factors are associated with poor cognitive outcome and which functions show persisting impairment. From 1134 children admitted with head injury to Red Cross and Groote Schuur Hospitals during a 2-year period, a consecutive sample of all those who had post-traumatic amnesia (PTA) over 1 hour, a compound depressed or basal skull fracture, a seizure, or any evidence of neurological involvement, was collected (n=388). Further requirements that they should be between 6 and 14 years, English or Afrikaans speaking, and have no history of significant cerebral pathology or mental retardation, reduced the sample to 123 children. Severity groups were formed according to the length of PTA: 56 moderates (PTA less than 1 day), 40 severes (PTA 1 to 7 days), and 28 very severes (PTA more than 7 days). They were matched for age, sex, socioeconomic status and ethnic group with 46 controls who had traumatic injury not involving the head. Detailed accident, medical and psychosocial data were collected. The children were assessed on a battery of tests covering intelligence, language, motor speed, visuographic and memory functions, as soon as they were out of PTA (Tl), 3 months later (T2), and at 1-year post-injury (T3). The 4 groups are compared at each interval on Tukey' s studentized range test and the extent of recovery within and between the groups is compared by repeated measures analysis of variance

Die mögliche Rolle der antennalen Cuticularporen beim Sexualverhalten von Cyaneolytta sp. (Coleoptera: Meloidae)

Cantharidin, which is mainly found in blister beetles (Coleoptera: Meloidae), is one of the most intensively studied natural products of insect (Dettner, 1997; McCormick & Carrel, 1987). The involvement of cantharidin in courtship behaviour has been already confirmed for certain canthariphilous insects (Eisner & al. 1996a,b; Frenzel & Dettner 1994; Frenzel & al. 1992; Schütz & Dettner, 1992; Hemp & al. 1999). The function and intrinsinc role of cantharidin in the courtship behaviour of Meloids has been never fully established. McCormick & Carrel (1987) only suggested that cantharidin might be used by female meloids when selecting a mate at close range. Pinto (1974, 1975) was, in fact, the first to consider male cuticular pores as being involved in the courtship behaviour of species from the genus Linsleya and Tegrodera (Meloidae). Based on morphology and chemical analyses of Cyaneolytta sp. (Coleoptera: Meloidae), we have hereby provided some further evidences that cantharidin may act as an infochemical in courtship behaviour of meloid beetles.Ölkäfer (Col: Meloidae) gehören zu den Insekten mit medizinischer Bedeutung. Cantharidin, das im gesamten Körper (v.a. in den Sexualorganen beider Geschlechter) der Käfer zu finden ist, verursacht Blasen auf der Haut. Die mögliche Rolle des Cantharidins im Sexualverhalten der Ölkäfer ist von besonderem wissenschaftlichem Interesse. Cyaneolytta sp. wurde in Karen, Kenia, gesammelt. Nach der Sektion wurden die Insektenkompartimente hydrolysiert und mittels quantitativer GC-MS chemisch analysiert. Um Poren der Kutikula und andere äußere Merkmale zu untersuchen, wurde ein Rasterelektronenmikroskop verwendet. Für Dünnschnitte der inneren Gewebe wurden Mikrotomschnitte angefertigt. Statistische Analysen wurden mit dem Softwarepaket Statistica durchgeführt. In den Antennen von Cyaneolytta sp. Péringuey, 1909 finden sich extrem hohe Cantharidinmengen. Die Daten zeigen eine deutliche Korrelation zwischen der Dichte der Kutikularporen und dem Cantharidingehalt der Antennenglieder Scapus und Pedicellus der Cyaneolytta-Männchen. Es existieren zahlreiche kanalartige Strukturen, die sich von der Hämolymphe der Antennen zur Oberfläche erstrecken, wo sich die Kutikularporen befinden. Betrachtet man den Cantharidingehalt der Antennensegmente, so enthalten die Glieder der Männchen viel größere Mengen als die der Weibchen. Auch besitzen die Kutikularporen der Weibchen eine deutlich geringere Dichte auf den Antennensegmenten. Die kanalartigen Strukturen auf den ersten beiden Antennensegmenten der Weibchen könnten uni- oder multizelluläre Tubuli sein, die das in der Hämolymphe zirkulierende Cantharidin an die Oberfläche bringen, aber die Poren auf den Antennen der Weibchen müssen eine andere Funktion haben. Während des Balzverhaltens berühren sich beide Geschlechter mit den Antennen, wobei die cantharidinhaltigen Poren in direkten Kontakt mit den weiblichen Antennen gelangen. Es wird vermutet, dass Cantharidin an die Oberfläche der Antennen der Männchen abgegeben wird. Demnach könnte der porenhaltige Bereich der männlichen Antennen eine Struktur sein, die Cantharidin abgibt, während der porenhaltige Bereich der weiblichen Antennen ein Rezeptorfeld darstellen könnte, dessen Chemorezeptoren einen bevorzugten Geschlechtspartner erkennen. Damit wurden weitere Hinweise für die Hypothese gesammelt, dass Cantharidin eine Rolle bei der sexuellen Selektion im Nahbereich spielt

Notes on the problem of the optimum design of structures

The urgent need for a systematic approach to the problems of the optimum design of structures is stressed and ideal formulations of these problems are considered. Differential equations and a variational principle are derived for the case of plates loaded in their own planes; these can form the basis for approximate solutions, in the form of optimum distributions of plate thickness and the corresponding stress distributions which are required to equilibrate given systems of external loads

Plastic buckling of a plate in shear

This note derives the mathematical equations for the analysis of the shear buckling of a plate, in the case where the initial stresses exceed the elastic limit of the material. It is hoped at a later stage to apply this theory to test results, which are being obtained using rectangular torsion boxes

Review of the African genera Arantia Stål and Goetia Karsch (Orthoptera. Tettigoniidae: Phaneropterinae).

The genus Arantia is reviewed, the distribution and distinguishing characters given. The three species of Goetia are assigned as subgenus to Arantia. Arantia gestri Griffini is transferred to this new subgenus and synonymized with G. dimidiata Bolívar. Other species synonymized are: A. accrana Karsch with A. rectifolia Brunner von Wattenwyl; A. gabunensis Brunner von Wattenwyl with A. regina Karsch; A. mammisignum Karsch and A. tigrina Bolívar with A. excelsior Karsch; A. ugandana Rehn is synonymized with A. fasciata (Walker). 6 species from Tropical Africa are newly described: A. (Arantia) quinquemaculata n. sp., A. (Arantia) ivoriana n. sp., A. (Euarantia) tanzanica n. sp., A. (Euarantia) tibiaspinosa n. sp., A. (Euarantia) bispinosa n. sp. and A. (Euarantia) griffinii n. sp. A key to the subgenera and species of Arantia is provided. The tribe Arantiini is synonymized with Holochlorini