The Permanent Okavango River Basin Water Commission annual report 2009

First published annual report of OKACOM, covering first period of Sida-funded three year workplan from 2007 until 2009, during which the Secretariat was established. (PDF contains 32 pages)

Comparison of permanent and temporary streams of calcareous Provence [Translation from: Annales de Limnologie 9(3) 273-292, 1973]

The rainfall regime and the karstic nature of the subsoil determines the alternation of a period of flow and a period of drought for a large number of Mediterranean streams. Amongst this type of stream it is possible to distinguish temporary streams, characterised by a period of flow for several months permitting the establishment of the principal groups of aquatic insects; and ephemeral streams whose very brief period of flow permits the establishment of a community reduced to a few species of Diptera. This paper aims to study the structure of the communities which colonise this particular type of stream and the ecology of the principal species which constitute these communities. Four French temporary streams were examined and temperature regimes, dissolved oxygen, calcium and magnesium measured. Samples of fauna were taken regularly and the biotic composition established. The analysis of similarities between the three permanent streams are discussed and compared with permanent streams.

Analysis of permanent magnets as elasmobranch bycatch reduction devices in hook-and-line and longline trials

Previous studies indicate that elasmobranch fishes (sharks, skates and rays) detect the Earth’s geomagnetic field by indirect magnetoreception through electromagnetic induction, using their ampullae of Lorenzini. Applying this concept, we evaluated the capture of elasmobranchs in the presence of permanent magnets in hook-and-line and inshore longline fishing experiments. Hooks with neodymium-iron-boron magnets significantly reduced the capture of elasmobranchs overall in comparison with control and procedural control hooks in the hook-and-line experiment. Catches of Atlantic sharpnose shark (Rhizoprionodon terraenovae) and smooth dogfish (Mustelus canis) were signif icantly reduced with magnetic hook-and-line treatments, whereas catches of spiny dogfish (Squalus acanthias) and clearnose skate (Raja eglanteria) were not. Longline hooks with barium-ferrite magnets significantly reduced total elasmobranch capture when compared with control hooks. In the longline study, capture of blacktip sharks (Carcharhinus limbatus) and southern stingrays (Dasyatis americana) was reduced on magnetic hooks, whereas capture of sandbar shark (Carcharhinus plumbeus) was not affected. Teleosts, such as red drum (Sciaenops ocellatus), Atlantic croaker (Micropogonias undulatus), oyster toadfish (Opsanus tau), black sea bass (Centropristis striata), and the bluefish (Pomatomas saltatrix), showed no hook preference in either hook-and-line or longline studies. These results indicate that permanent magnets, although eliciting species-specific capture trends, warrant further investigation in commercial longline and recreational fisheries, where bycatch mortality is a leading contributor to declines in elasmobranch populations.

Por entre histórias e memórias: caminhos do curso de formação de professores do Colégio Estadual Trasilbo Filgueiras (19841985)

A presente dissertação centra-se na investigação das memórias e histórias da criação do Curso de Formação de Professores em nível médio, do Colégio Estadual Trasilbo Filgueiras, localizado no bairro Jardim Catarina, no município de São Gonçalo. O recorte temporal da pesquisa concentra-se no início da oferta do referido curso os anos de 1984 e 1985. A partir de um enfoque metodológico de natureza qualitativa, buscamos em fontes documentais - arquivo permanente da instituição escolar e impressos do Jornal O SÃO GONÇALO -, em diálogo com fontes orais - narrativas dos/as moradores/as, professoras, funcionários/as e alunas egressas - indícios (GINZBURG, 1989) das histórias vividas neste espaço formativo. As questões que este trabalho de investigação se propõe a discutir são: Por que foi criado o Curso de Formação de Professores no Colégio Estadual Trasilbo Filgueiras? Que narram os sujeitos da pesquisa sobre a criação do curso na instituição? A relação memória e história são compreendidas a partir de Benjamim (1996) e Nunes (2003), em uma perspectiva de que passado é entendido como tempo presente ao ser rememorado. A escala de análise (REVEL, 1998) é utilizada como ferramenta reflexiva da interação entre os diferentes sujeitos sociais. Sujeitos sociais que cotidianamente, no âmbito da esfera local e global, constroem os processos históricos mediante suas práticas culturais, relações sociais e modos de vida. A pesquisa justifica-se pela necessidade da reflexão, da rememoração e valorização das memórias escolares e da história da formação de professores no município de São Gonçalo, com vistas ao fortalecimento das instituições públicas que a desenvolvem. Palavras-chave: Curso

Optimum Magnetic Circuit Configurations for Permanent Magnet Aerospace Generators

In the design of high-speed low-power electrical generators for unmanned aircraft and spacecraft, maximization of specific output (power/weight) is of prime importance. Several magnetic circuit configurations (radial-field, axial-field, flux-squeezing, homopolar) have been proposed, and in this paper the relative merits of these configurations are subjected to a quantitative investigation over the speed range 10 000–100000 rev/min and power range 250 W-10 kW. The advantages of incorporating new high energy-density magnetic materials are described. Part I deals with establishing an equivalent circuit for permanent-magnet generators. For each configuration the equivalent circuit parameters are related to the physical dimensions of the generator components and an optimization procedure produces a minimum volume design at discrete output powers and operating speeds. The technique is illustrated by a quantitative comparison of the specific outputs of conventional radial-field generators with samarium cobalt and alnico magnets. In Part II the specific outputs of conventional, flux-squeezing, and claw-rotor magnetic circuit configurations are compared. The flux-squeezing configuration is shown to produce the highest specific output for small sizes whereas the conventional configuration is best at large sizes. For all sizes the claw-rotor configuration is significantly inferior. In Part III the power densities available from axial-field and flux-switching magnetic circuit configurations are maximized, over the power range 0.25-10 kW and speed range 10 000–100000 rpm, and compared to the results of Parts I & II. For the axial-field configuration the power density is always less than that of the conventional and flux-squeezing radial-field configurations. For the flux-switching generator, which is able to withstand relatively high mechanical forces in the rotor, the power density is again inferior to the radial-field types, but the difference is less apparent for small (low power, high speed) generator sizes. From the combined results it can be concluded that the flux-squeezing and conventional radial-field magnetic circuit configurations yield designs with minimum volume over the power and speed ranges considered. © 1985, IEEE. All rights reserved.