Two new species of the aquatic beetle genus Macrelmis Motschulsky from Venezuela (Coleoptera: Elmidae: Elminae)

Two new species collected in northwestern Venezuela, Macrelmis milleri aneI M. hayelwe, are described and illustrated by line drawings and scanning electron micrographs. Both species are assigned to the new species group Macrelmis milleri, and characters of the new species group are described. A key to the species of the group is given

A new tribe, genus, and species of limnichid beetle, Wooldridge us perforatus, from Malaysia (Coleoptera: Limnichidae: W ooldridgeini)

A new tribe is established in the Limnichidae, Limnichinae, for a new genus and species, Wooldridge us perforatus, from Sabah, Malaysia. Two autapomorphic characters distinguish Wooldridgeini from the two other tribes ofthe subfamily Limnichinae; 1) the mesotarsus and metatarsus join their respective tibia ventrally (medially) and preapically instead of the usual apical only connection and 2) a large pore, presumed to be an opening of a prothoracic gland, is present on each hypomeron. Distinguishing characters are illustrated by scanning electron micrographs and line drawings. A key to the three tribes included in the Limnichinae is provided

Self-generated and externally driven current oscillations in n-GaAs

Experimental investigations of self-generated and externally driven non-linear current oscillations due to impact ionization of shallow impurities in n-type GaAs at low temperatures are presented. The regular relaxation oscillations which appear at the onset of breakdown are destabilized by a magnetic field normal to the epitaxial layer and multifrequency oscillations and chaotic fluctuations following the Ruelle-Takens-Newhouse scenario can be found. Driving the self-generated oscillations with an external periodic bias voltage quasiperiodicity, mode locking, interaction and overlap of mode locked resonances and period doubling can be observed depending on frequency and amplitude of the external force. The reconstructed return maps, recorded phase diagrams and Devil's staircase agree with theoretical predictions based on the circle map and give new evidence of the universality of the transition from quasiperiodicity to chaos

Study of vortex boundary layer interactions Final report, period ending 26 Jun. 1966

Vortex-boundary layer interaction, and turbulent pipeflow at very low speed

A sensitive magnetic balance for the direct measurement of skin friction drag

Sensitive magnetic balance for direct measurement of skin friction dra

A checklist of the Limnichidae and the Lutrochidae (Coleoptera) of the world

A checklist of the world species of Limnichidae (35 genera, 345 species) and Lutrochidae (1 genus, 11 species) is presented. The author, year of publication and page number, synonyms, distribution by country, and a terminal bibliography are given for each genus and species. Biological information is also reviewed

Rediscovery and redescription of Ceradryops punctatus Hinton, 1937 (Coleoptera: Dryopidae)

Ceradryops punctatus Hinton from Sri Lanka is redescribed and illustrated. Notes are made on the habitat of the species

Luchoelmis : a new genus of Elmidae (Coleoptera) from Chile and Argentina

Luchoelmis New Genus is described with four new species: aequalis, magallanensis, and penai from Chile and cekalovici from Argentina and Chile. Luchoelmis penai is designated as the type species of the genus. A key to the four species is presented

Three new species of Hexanchorus Sharp, 1882 (Coleoptera: Elmidae: Larainae) from South America

Three new species of Hexanchorus Sharp, H. dimorphus and H. shannoni from Argentina, and H. mcdiarmidi from Venezuela, are described and illustrated

Injection of a drag-reducing fluid into turbulent pipe flow of a Newtonian fluid

Injection of drag reducing fluid into turbulent pipe flow of Newtonian flui