989 resultados para Marcks, Erich, 1861-1938.


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O historiador Frederick Jackson Turner (1862-1931) é considerado o grande pai da historiografia moderna nos Estados Unidos. Sua frontier thesis postulava a centralidade da expansão das fronteiras ocidentais no processo de formação da nacionalidade estadunidense e na consolidação da democracia política naquela nação, abandonando uma história política factual e introduzindo uma interpretação calcada em fatores econômicos e sociais, com claras implicações presentistas. Graças a esta análise revolucionária, Turner tornou-se uma espécie de patrono da profissionalização da disciplina nos Estados Unidos, formando toda uma geração de historiadores a partir de seus seminários na Universidade Estadual do Wisconsin e em Harvard. Não só isso, mas a sua teoria encontrou apelo entre elementos da classe política e empresarial, incluindo dois Presidentes da República, Theodore Roosevelt (1901-1909) e Woodrow Wilson (1913-1921). A explicação para tal sucesso pode ser encontrada na relação entre a frontier thesis e o Mito da Fronteira, através de uma narrativa que fazia uso dos ícones e imagens do Mito enquadrados em uma retórica extremamente persuasiva. Nas páginas dos escritos de Turner, os norte-americanos marcham triunfalmente em direção a conquista de todo o continente, justificada pelo seu amor à democracia e por sua devoção ao progresso material e mental dos homens. Com isso, o historiador conseguiu unir uma valorização do agrarianismo primitivo com um elogio à evolução histórica dos Estados Unidos.

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The citrus-growing ecosystem houses a great deal of species of natural enemies, among them Chrysoperla externa (Hagen, 1861), which presents a great potential for use in the biological control of pests. The aim of this work was to evaluate the effects of the preys Planococcus citri (Risso, 1813) and Toxoptera citricida (Kirkaldy, 1907) on the development of larva and pupa of C. externa. The trial was carried out in an acclimatized room at 25 +/- 1 degrees C, 70 +/- 10% RH and 12-hour photophase, the treatments consisting of the continuous and alternate supply of those two preys in each instar of the predator, in addition to eggs of Anagasta kuehniella (Zeller, 1879) utilized for comparison purposes. Both the white mealybug and the aphids were given in sufficient amounts to the C. externa larvae to be able to feed ad libitum. The lifetime and the survival rate of the phases of larva, pupa and the larval-adult period of C. externa were evaluated. It was found that T. citricida given either singly along the larval development or in two consecutive instars of the predator was not an adequate prey, 100% of mortality over the larval-adult period being found. When the larvae fed on P. citri, given in two instars of the predator, the survival rate in the larval-adult period was similar to the diet constituted of only A. kuehniella eggs, except when fed with T. citricida in the first instar.

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Many arthropods are mentioned with whitefly natural enemies, including the green lacewings. The aim of this study is to analyses the development and the capacity of predation of Chrysoperla externa (Hagen, 1861) fed with Bemisia tabaci B biotype nymphs, rearing different vegetables (kale, broccoli, eggplant end tomato). The duration, viability end weight in each stage end phase of development of the insect-predator had been evaluated, as well as the predatory capacity of the larvae in the third instar. The larval phase of the predator presented minor duration when these had been fed with nymphs developed the broccoli (12.36 days) and minor duration of the tomato (14.36 days) phase when fed with nymphs developed in kale, broccoli, and eggplant (6.50, 7.20, 7.33 days, respectively). The lower indices of viability been found for the larvae fed with nymphs developed in the tomato (30%), and average weights have. The predatory capacity of the larvae during the third instar was not affected, independently on the plant host where the whitefly nymph fed itself.

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Marine aquaculture has developed in the last decades all over the world, especially related to shrimp management. In Brazil, the introduction of the species Litopenaeus vannamei has contributed to the success of the activity, even if there are problems associated with the management of a exotic species, such as new diseases and ecological pressure on native species. It has been emphasized the need of research for developing new methodology that will allow native species management, being the most important Farfantepenaeus subtilis and Litopenaeus schmitti. Most knowledge obtained from research with those species has generally used a technical approach and mainly focused feeding process. There are no specific behavioral data on their activity pattern which should be of great importance for the use of native species on commercial culture farms. So, it was our objective to study and compare the daily distribution of behavioral activities of the marine shrimp species Litopenaeus schmitti and Farfantepenaeus subtilis. Forty animals of each species, 5 individuals per aquarium, were maintained in aquaria containing 200L of sea water under continuous aeration and filtration. They were marked individually and were observed by the instantaneous focal time sampling, along 10 continuous days, in 6 daily 15 min observation windows, every two hour. In each window, behaviors and location position of the animals in the aquarium were registered at 1 min intervals. Food was offered 3 times a day, representing 10% of each aquarium biomass. Aquaria were maintained in artificial photoperiod, 12hour light/l2 hour dark, 4 aquaria in light cycle equivalent to the environmental one (light from 06:00 to 17:59 h and dark from 18:00 to 05:59 h) and the other 4 in the reverse light cycle (light from 18:00 to 05:59 h and dark from 06:00 to 17:59 h) to allow sequential behavioral observation in both phases of the 24 hour cycle. There was a clear distinction between the distribution of behavioral activities of F. subtilis and L. schmitti in the two phases. The activity pattern of Farfantepenaeus subtilis demonstrates that species has prominently night habits and a burying pattern during the light cycle. Exploration, inactivity and swimming were the most common activities. The behavioral pattern of Litopenaeus schmitti indicates that species is active along both phases of the light cycle, and the most evident behaviors were exploration, inactivity and swimming

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)