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Search Results: 1 - 10 of 13057 matches for " Marcelo;Mielke "
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Copula "inter mares" in Pirascca sagaris satnius (Dalman) (Lepidoptera, Riodinidae, Riodininae)
Duarte, Marcelo;Mielke, Olaf H.H;Casagrande, Mirna M;
Revista Brasileira de Zoologia , 2000, DOI: 10.1590/S0101-81752000000200026
Abstract: the poorly known phenomenon of copula "inter mares" (a male insect copulating with another male) is reported in pirascca sagaris satnius (dalman, 1823) (lepidoptera, riodinidae, riodininae).
Morfologia externa do adulto de Hemiargus hanno (Stoll) (Lepidoptera, Lycaenidae, Polyommatinae, Polyommatini): I. cabe?a
Duarte, Marcelo;Casagrande, Mirna M.;Mielke, Olaf H.H.;
Revista Brasileira de Zoologia , 2001, DOI: 10.1590/S0101-81752001000100025
Abstract: this is the first of a series of contributions concerning exoskeletal morphology of neotropical lycaenid butterflies (blues and hairstreaks). the cephalic capsule morphology of hemiargus hanno (stoll, 1790) is herein presented with drawings and sem photographs.
Determina??o do tempo de hidrodestila??o e do horário de colheita no óleo essencial de menta
Oliveira, Ariana RMF de;Jezler, Caroline N;Oliveira, Rosilene A;Mielke, Marcelo S;Costa, Larissa CB;
Horticultura Brasileira , 2012, DOI: 10.1590/S0102-05362012000100026
Abstract: the extraction time and harvest moment are important information in the study of herbs. they can maximize the efficiency of the extraction process and the amount of essential oil produced. the objective of this study was to determine the time of hydrodistillation and evaluate the effect of the harvest moment on the content, yield and chemical composition of essential oil of mentha x piperita var citrata. the treatments consisted of four extraction times (30, 60, 90 and 120 min) and five harvest moments (9:00, 11:00, 13:00, 15:00 and 17:00 hours) with four replications arranged in a randomized design. after 60 minutes of hydrodistillation in clevenger apparatus the volume extracted stabilized. in relation to the harvest moment, a significant variation was observed in the essential oil content throughout the day, the highest value (1.33%) being found in samples taken at 13:00h. variation in the chemical composition of essential oil was also noticed and higher contents of α-fenchol and cis-myrtanol were verified in the morning and in the afternoon, respectively.
Photosynthetic traits of five neotropical rainforest tree species: interactions between light response curves and leaf-to-air vapour pressure deficit
Mielke, Marcelo Schramm;Almeida, Alex-Alan Furtado de;Gomes, Fábio Pinto;
Brazilian Archives of Biology and Technology , 2005, DOI: 10.1590/S1516-89132005000600018
Abstract: measurements of leaf gas exchange at different photosynthetic photon flux density (ppfd) levels were conducted in order to compare the photosynthetic traits of five neotropical rainforest tree species, with a special emphasis on empirical mathematical models to estimate the light response curve parameters incorporating the effects of leaf-to-air vapour pressure deficit (d) on the saturated photosynthetic rate (amax). all empirical mathematical models seemed to provide a good estimation of the light response parameters. comparisons of the leaf photosynthetic traits between different species needed to select an appropriate model and indicated the microenvironmental conditions when the data were collected. when the vapour pressure deficit inside the chamber was not controlled, the incorporation of linear or exponencial functions that explained the effects of d on leaf gas exchange, was a very good method to enhance the performance of the models.
Butterflies (Lepidoptera, Papilionoidea and Hesperioidea) of the "Baixada Santista" region, coastal S?o Paulo, southeastern Brazil
Francini, Ronaldo Bastos;Duarte, Marcelo;Mielke, Olaf Hermann Hendrik;Caldas, Astrid;Freitas, André Victor Lucci;
Revista Brasileira de Entomologia , 2011, DOI: 10.1590/S0085-56262011000100010
Abstract: butterflies (lepidoptera, papilionoidea and hesperioidea) of the "baixada santista" region, coastal s?o paulo, southeastern brazil. a list with 538 species of butterflies recorded in the baixada santista, s?o paulo ( se brazil) is presented. standard sampling protocols (i.e. with entomological nets) were followed. baited traps were installed for fruit feeding species. data from the literature and entomological collections were also considered in the total estimated species richness. the species richness recorded in the baixada santista region represents about 16% of the brazilian butterfly fauna, and 34% of the known butterfly fauna for the state of s?o paulo. the present list contains an appreciably higher number of species in comparison to other lists from similar biomes farther south, such as blumenau in santa catarina, and maquiné in rio grande do sul.
Efeitos do alagamento do substrato no crescimento e na composi??o química de genótipos clonais de Theobroma cacao L.
Rehem, Bruna Carmo;Almeida, Alex-Alan Furtado de;Mielke, Marcelo Schramm;Gomes, Fábio Pinto;
Revista Brasileira de Fruticultura , 2009, DOI: 10.1590/S0100-29452009000300026
Abstract: soil flooding can induce changes in cell metabolism and cause deviations in optimum conditions for plant growth, creating a stress condition. the objective of this work was to evaluate the effects of flooding on growth and mineral nutrition of six t. cacao clones (cp-49, ccn-10, cp-06, cepec-2007, cepec-2008 and ps-1319), aiming to clarify the possible mechanisms of soil flooding tolerance. plants of t. cacao with 6 months of age were subject to soil flooding, along with the control treatment (not flooded), for 30 days. at the end of the experiment, flooding induced decreases in the root growth rates (except for cp-06) and leaf area, increases in the dry mass, in the stem relative growth rate (except for the clones cp-06 and cepec-2008), in the net assimilation rates (except for ps-1319) and in the specific leaf mass of the clones cp-49, ccn-10 and cp-06. plants that survived the 30 days of flooding also presented low values of the leaf area ratio. in general, substrate flooding has caused disability in the absorption of macro and micro nutrients, with exception for fe. among all clones evaluated, cp-49 was considered as tolerant and cepec-2008 as non-tolerant to soil flooding. the other clones are in an intermediate position. therefore, the clone cp-49 presents a great potential to be cultivated in flood prone environments.
Notes on the last instar larva and pupa of Hemiargus hanno (Stoll) (Lepidoptera, Lycaenidae, Polyommatinae)
Duarte, Marcelo;Almeida, Gisele Luziane de;Casagrande, Mirna Martins;Mielke, Olaf H.H.;
Revista Brasileira de Zoologia , 2001, DOI: 10.1590/S0101-81752001000400008
Abstract: larvae of hemiargus hanno (stoll, 1790) (lepidoptera, lycaenidae, polyommatinae) are for the first time reported to be attended under field conditions by ants of the formicine genus brachymyrmex mayr, 1868 (myrmelachistini). structural features of the last instar larva and pupa of h. hanno are described and illustrated with the aid of scanning electron microscopy (sem).
Calculating critical temperatures of superconductivity from a renormalized Hamiltonian
Andreas Mielke
Physics , 1997, DOI: 10.1209/epl/i1997-00445-5
Abstract: It is shown that one can obtain quantitatively accurate values for the superconducting critical temperature within a Hamiltonian framework. This is possible if one uses a renormalized Hamiltonian that contains an attractive electron-electron interaction and renormalized single particle energies. It can be obtained by similarity renormalization or using flow equations for Hamiltonians. We calculate the critical temperature as a function of the coupling using the standard BCS-theory. For small coupling we rederive the McMillan formula for Tc. We compare our results with Eliashberg theory and with experimental data from various materials. The theoretical results agree with the experimental data within 10%. Renormalization theory of Hamiltonians provides a promising way to investigate electron-phonon interactions in strongly correlated systems.
Ferromagnetism in single-band Hubbard models with a partially flat band
Andreas Mielke
Physics , 1999, DOI: 10.1103/PhysRevLett.82.4312
Abstract: A Hubbard model with a single, partially flat band has ferromagnetic ground states. It is shown that local stability of ferromagnetism implies its global stability in such a model: The model has only ferromagnetic ground states if there are no single spin-flip ground states. Since a single-band Hubbard model away from half filling describes a metal, this result may open a route to metallic ferromagnetism in single band Hubbard models.
Similarity renormalization of the electron--phonon coupling
Andreas Mielke
Physics , 1996, DOI: 10.1002/andp.19975090305
Abstract: We study the problem of the phonon-induced electron-electron interaction in a solid. Starting with a Hamiltonian that contains an electron-phonon interaction, we perform a similarity renormalization transformation to calculate an effective Hamiltonian. Using this transformation singularities due to degeneracies are avoided explicitely. The effective interactions are calculated to second order in the electron-phonon coupling. It is shown that the effective interaction between two electrons forming a Cooper pair is attractive in the whole parameter space. For a simple Einstein model we calculate the renormalization of the electronic energies and the critical temperature of superconductivity.
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