875 research outputs found
Présence de Sergentomyia schwetzi Adler, Théodor et Parrot (Diptera, Phlebotomidae) dans le Sud marocain
Sur deux nouveaux phlébotomes de la Guyane française : Lutzomyia yuili pajoti n. s. sp. et Lutzomyia claustrei n. sp.
From single particle to superfuid excitations in a dissipative polariton gas
Using angle-resolved heterodyne four-wave-mixing technique, we probe the low
momentum excitation spectrum of a coherent polariton gas. The experimental
results are well captured by the Bogoliubov transformation which describes the
transition from single particle excitations of a normal fluid to
sound-wave-like excitations of a superfluid. In a dense coherent polariton gas,
we find all the characteristics of a Bogoliubov transformation, i.e. the
positive and negative energy branch with respect to the polariton gas energy at
rest, sound-wave-like shapes for the excitations dispersion, intensity and
linewidth ratio between the two branches in agreement with the theory. The
influence of the non-equilibrium character of the polariton gas is shown by a
careful analysis of its dispersion.Comment: 4 pages, 3 figure
2D Fourier Transform Spectroscopy of exciton-polaritons and their interactions
We investigate polariton-polariton interactions in a semiconductor
microcavity through two-dimensional Fourier transform (2DFT) spectroscopy. We
observe, in addition to the lower-lower and the upper-upper polariton
self-interaction, a lower-upper cross-interaction. This appears as separated
peaks in the on-diagonal and off-diagonal part of 2DFT spectra. Moreover, we
elucidate the role of the polariton dispersion through a fine structure in the
2DFT spectrum. Simulations, based on lower-upper polariton basis
Gross-Pitaevskii equations including both self and cross-interactions, result
in a 2DFT spectra in qualitative agreement with experiments
Alterações fisiológicas em videira (Vitis sp.) cultivada em solo com acúmulo de Cu e fitoproteção com fungos micorrízicos arbusculares
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias, Programa de Pós-Graduação em Recursos Genéticos Vegetais, Florianópolis, 2015.As videiras frequentemente são submetidas às aplicações sucessivas de fungicidas cúpricos que causam acúmulo de Cobre (Cu) no solo, o que pode causar toxidez as videiras transplantadas em solos de vinhedos antigos erradicados. A disponibilidade de Cu às plantas pode ser restringida pela calagem, ou ainda, a toxidez pode ser amenizada através da inoculação das plantas com fungos micorrízicos arbusculares (FMA). O objetivo dos estudos foi avaliar o desempenho de videiras jovens cultivadas em solo com alto teor de Cu através da calagem e inoculação com FMA. Com isso, está dissertação se divide em três capítulos. O experimento de capítulo 1 e 2 foi conduzido em ambiente controlado. Os tratamentos consistiram de duas doses de Cu (0 e 50 mg kg-1) e três de calcário (0,0; 1,5 e 3,0 Mg ha-1) em Argissolo Vermelho. As plantas foram acondicionadas em rhizobox e cultivadas durante dez semanas. Foram determinadas taxas de trocas gasosas, matéria seca de raízes, caule e folhas, número de folhas, diâmetro do colmo, número de nós, e foi quantificado o teor de clorofilas a, b e total, carboidratos solúveis, amido, proteínas, Cu, N, P, K, Ca e Fe totais nas folhas. O cultivo de videiras jovens ?Niágara Branca? (Vitis labrusca) em solo com adição de Cu foi prejudicado quando não houve calagem ou a mesma foi de 1,5 Mg ha-1, resultando em menor desenvolvimento e redução dos teores de nutrientes na folha. A aplicação de 3,0 Mg ha-1 de calcário, reduziu os efeitos tóxicos do Cu sobre as plantas de videira cultivadas em solo com a adição de 50mg kg-1 de Cu. O experimento do capítulo 3 foi conduzido em casa de vegetação, utilizando-se solo de um vinhedo comercial com teores elevados de Cu. No momento do transplante das plantas para os vasos, as raízes foram inoculadas com os FMA: D. heterogama, A. morrowiae e R. clarus, além de um tratamento testemunha. O cultivo foi mantido durante 10 semanas, no qual foi foram obtidos os dados referentes à altura de planta, área foliar de planta, as taxas de trocas gasosas, colonização micorrízica, MS de raízes, caule e folha, número de folhas, diâmetro de colmo, teores de carboidratos solúveis totais, amido total, Clorofila a, b e total, carotenoides, teores de Cu e P nas plantas. A inoculação com R. Clarus foi o responsável pelo maior incremento em altura, MS de folhas, MS de caule e colonização micorrízica e menor teor ne Cu nas folhas das videiras. Conclui-se que os FMA são capazes de amenizar a toxidez as plantas e contribuir para o estabelecimento das mudas em vinhedos com alto teor de Cu no solo.Abstract : Successive applications of copper fungicides to grape vines can cause accumulation of copper (Cu) in soil, this potentially causing toxic effects on grape vines cultivated at old vineyards. However, Cu availability in the soil may be reduced through liming and the toxic effects of on plants alleviated through inoculation of mycorhizzal fungi (MF). The goal of this dissertation, divided into three chapters, was to evaluate the performance of young grape vines grown in soil with high Cu content, treated by liming, and inoculated with MF. Experiments for chapter one and two were conducted in a controlled environment. Treatments consisted of two doses of Cu (0 and 50 mg kg-1) and three of limestone (0.0, 1.5 and 3.0 Mg ha-1) in red agrisoil. The plants were placed in rhizoboxes and cultured for ten weeks. Gas exchange rates, root, stem, and leaf dry matter, number of leaves, stem diameter, number of nodes, quantity of chlorophylls a and b, total soluble carbohydrates, starch, proteins, Cu, N, P, K, Ca, and Fe in leaves were recorded. Young ?Niagara Branca? grape (Vitis labrusca) vines grown in soil with Cu with 0 or 1.5 Mg ha-1 limestone had restricted growth, resulting in lower development and reduction of leaf nutrient content. Application of 3.0 Mg ha-1 lime reduced the toxic on grape vines frown in soil with the addition of 50 mg kg-1 Cu. The experiment of Chapter 3 was conducted in a greenhouse using soil with high levels of Cu from a commercial vineyard. Grape vine roots were inoculated with MF: D. heterogama, A. morrowiae and R. clarus, plus a control treatment during transplant to pots for ten weeks. Plant height, leaf area, gas exchange rates, mycorrhizal colonization, root, stem, and leaf dry mass, number of leaves, stem diameter, total soluble carbohydrates, total starch, chlorophyll a and b content, total carotenoids and concentration of Cu and P were recorded. Inoculation with R. clarus promoted the greatest height growth, leaf and stem dry weight, mycorrhizal colonization and decreased Cu leaf content. It was concluded that the MF are able to alleviate Cu toxicity and contribute to improved grape cultivation in vineyards with heavy Cu content
The Slowly Formed Guiselin Brush
We study polymer layers formed by irreversible adsorption from a polymer
melt. Our theory describes an experiment which is a ``slow'' version of that
proposed by Guiselin [Europhys. Lett., v. 17 (1992) p. 225] who considered
instantaneously irreversibly adsorbing chains and predicted a universal density
profile of the layer after swelling with solvent to produce the ``Guiselin
brush.'' Here we ask what happens when adsorption is not instantaneous. The
classic example is chemisorption. In this case the brush is formed slowly and
the final structure depends on the experiment's duration, . We find
the swollen layer consists of an inner region of thickness with approximately constant density and an outer region
extending up to height which has the same density decay as for the Guiselin case.Comment: 7 pages, submitted to Europhysics Letter
Reaction-diffusion dynamics: confrontation between theory and experiment in a microfluidic reactor
We confront, quantitatively, the theoretical description of the
reaction-diffusion of a second order reaction to experiment. The reaction at
work is \ca/CaGreen, and the reactor is a T-shaped microchannel, 10 m
deep, 200 m wide, and 2 cm long. The experimental measurements are
compared with the two-dimensional numerical simulation of the
reaction-diffusion equations. We find good agreement between theory and
experiment. From this study, one may propose a method of measurement of various
quantities, such as the kinetic rate of the reaction, in conditions yet
inaccessible to conventional methods
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