982 resultados para Flat mites
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Magdeburg, Univ., Fak. für Mathematik, Habil.-Schr., 2014
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v.44:no.15(1962)
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v.65:no.1(1973)
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n.s. no.47(1988)
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v.34:no.28(1954)
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v.35:no.3(1954)
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n.s. no.62(1990)
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A population of Sesarma rectum Randall, 1840 under the influence of human impact was studied. Monthly sampling (CPUE, two people during 30 min) took place from August/2001 to July/2002 at an impacted muddy flat in Paraty city, State of Rio de Janeiro (23º13'S, 44º42'W). At the laboratory, specimens were classified by sex and measured with a vernier caliper (0.01 mm). The size at the beginning of the sexual maturity was obtained by means of different techniques: in the case of males it was used the allometric procedure and the macroscopic analysis of gonads wile for females, the size of the smallest ovigerous female was also considered. The population structure was evaluated by means the analysis of the variations in the modes of the size frequency distribution. The fecundity was assessed using sub samples of the egg mass. For males, the macroscopic analyses of gonads revealed larger values of carapace width than those obtained with morphometric analysis. Males larger than 18.5 mm of carapace width can be considered as mature. For females, such size was 17.4 mm CW. Despite of the human impact in the habitat, the population presented to be stable, as indicated by a single mode on the size frequency distribution. The second mode that appeared in some months is probably related to the entrance of juveniles in the population. The sex ratio of this population is closely approximating to 1:1 until crabs reach a carapace width of about 28 mm; after that, males outnumbered females. Comparing the fecundity of the present population with a previous study from Ubatuba, it can be verified a difference in the number of eggs. The fecundity of Paraty's population is significantly lower than the Ubatuba's population. This is probably related to the scarcity of food resource in Paraty, once no vascular plant can be found in that place. The continuity of reproductive processes and the juvenile recruitment suggest this species is able to live in the area with human impact. The ability to obtaining nutrients from different source of food is probably a feature that allows S. rectum to occupy such impacted ecosystem.
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Tadarida brasiliensis (Geoffroy, 1824), the Brazilian free-tailed bat, is an insectivorous bat that occurs from southern United States of America to southern South America. In this study we present the first data on diversity of ectoparasitic mites of T. brasiliensis in Brazil. A compilation and analysis of the studies of mite diversity conducted in different points the geographic distribution this bat species are provided. The mites were collected from March 2010 to November 2011 on 160 T. brasiliensis adult bats captured in southern Brazil. Four species of mites have been found: Chiroptonyssus robustipes (Ewing, 1925), Ewingana longa (Ewing, 1938), Ewingana inaequalis (Radford, 1948), and specimens of Cheyletidae. Chiroptonyssus robustipes was the most prevalent species (100%), followed by E. longa (20%), E. inaequalis (10%), and specimens of Cheyletidae (1.25%). The data currently available show that C. robustipes parasitizes T. brasiliensis throughout its region of occurrence, and this mite is highly prevalent and abundant. The two species of Ewingana accompany the geographical distribution of T. brasiliensis, but with much lower prevalence and abundance.
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Alguns van considerar el 2000 l'any del llibre electrònic però el fracàs de les empresespunt.com no el va fer possible . En canvi, va ser a principis de 2004 quan hi va haver el major número de compres de llibres-e amb més de 3 milions de dòlars en vendes. Una enquesta de consum del 2002 va trobar que el 67% dels enquestats volien llegir llibres-e i que el 62% volien tenir accés a llibres-e a la biblioteca. Malauradament, la gran quantitat d'informació escrita sobre els llibres-e ha començat a generar una sèrie de mites sobre el seu ús, funcionalitat i cost. L'autor considera que aquests mites poden interferir en el paper de les biblioteques per ajudar a determinar el futur del suport i del seu accés. És important que els bibliotecaris, en comptes de fixar-se en els pros i contres de la tecnologia dels llibres-e, es comprometin i ajudin a aclarir el paper dels documents digitals en la biblioteca moderna.
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"Vegeu el resum a l'inici del document del fitxer adjunt."
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The life cycle of ear mites of the genus Raillietia Trouessart consists of egg, larva, proto-and deutonymph and adult. The proto-and deutonymph are free living, non feeding instars. The teneral adult is the transfer stage. The minimum period required for completion of the life cycle is approximately eight days.
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BACKGROUND: The population genetic structure of a parasite, and consequently its ability to adapt to a given host, is strongly linked to its own life history as well as the life history of its host. While the effects of parasite life history on their population genetic structure have received some attention, the effect of host social system has remained largely unstudied. In this study, we investigated the population genetic structure of two closely related parasitic mite species (Spinturnix myoti and Spinturnix bechsteini) with very similar life histories. Their respective hosts, the greater mouse-eared bat (Myotis myotis) and the Bechstein's bat (Myotis bechsteinii) have social systems that differ in several substantial features, such as group size, mating system and dispersal patterns. RESULTS: We found that the two mite species have strongly differing population genetic structures. In S. myoti we found high levels of genetic diversity and very little pairwise differentiation, whereas in S. bechsteini we observed much less diversity, strongly differentiated populations and strong temporal turnover. These differences are likely to be the result of the differences in genetic drift and dispersal opportunities afforded to the two parasites by the different social systems of their hosts. CONCLUSIONS: Our results suggest that host social system can strongly influence parasite population structure. As a result, the evolutionary potential of these two parasites with very similar life histories also differs, thereby affecting the risk and evolutionary pressure exerted by each parasite on its host.
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This paper studies global webs on the projective plane with vanishing curvature. The study is based on an interplay of local and global arguments. The main local ingredient is a criterium for the regularity of the curvature at the neighborhood of a generic point of the discriminant. The main global ingredient, the Legendre transform, is an avatar of classical projective duality in the realm of differential equations. We show that the Legendre transform of what we call reduced convex foliations are webs with zero curvature, and we exhibit a countable infinity family of convex foliations which give rise to a family of webs with zero curvature not admitting non-trivial deformations with zero curvature.
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In this paper a model is developed to describe the three dimensional contact melting process of a cuboid on a heated surface. The mathematical description involves two heat equations (one in the solid and one in the melt), the Navier-Stokes equations for the flow in the melt, a Stefan condition at the phase change interface and a force balance between the weight of the solid and the countering pressure in the melt. In the solid an optimised heat balance integral method is used to approximate the temperature. In the liquid the small aspect ratio allows the Navier-Stokes and heat equations to be simplified considerably so that the liquid pressure may be determined using an igenfunction expansion and finally the problem is reduced to solving three first order ordinary differential equations. Results are presented showing the evolution of the melting process. Further reductions to the system are made to provide simple guidelines concerning the process. Comparison of the solutions with experimental data on the melting of n-octadecane shows excellent agreement.