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31.
32.
Ramanathan A Wright KC Muniz SR Zelan M Hill WT Lobb CJ Helmerson K Phillips WD Campbell GK 《Physical review letters》2011,106(13):130401
We have created a long-lived (≈40 s) persistent current in a toroidal Bose-Einstein condensate held in an all-optical trap. A repulsive optical barrier across one side of the torus creates a tunable weak link in the condensate circuit, which can affect the current around the loop. Superflow stops abruptly at a barrier strength such that the local flow velocity at the barrier exceeds a critical velocity. The measured critical velocity is consistent with dissipation due to the creation of vortex-antivortex pairs. This system is the first realization of an elementary closed-loop atom circuit. 相似文献
33.
Muniz CR Freire FC Viana FM Cardoso JE Cooke P Wood D Guedes MI 《Micron (Oxford, England : 1993)》2011,42(5):419-428
Lasiodiplodia theobromae is a phytopathogenic fungus causing gummosis, a threatening disease for cashew plants in Brazil. In an attempt to investigate the ultrastructural features of the pathogen colonization and its response to immunofluorescence labeling, light, confocal and electron microscope studies were conducted on different severity scale patterns of diseased plants. Lasiodiplodia-antisera was checked for cross reactivity against common cashew plants fungi. Optical microscopy analysis revealed a longitudinally sectioned hyphae located within the xylem vessels, showing an extensive hyphal development in the secondary xylem tissue. SEM images demonstrated that the fungus was found in some asymptomatic samples, particularly within the xylem vessels as confirmed by the optical images. Symptomatic sample images showed an extensive distribution of the fungus along the secondary xylem, within the vessels, infecting xylem parenchyma. A closer look in the secondary xylem parenchyma reveals a heavy and profuse invasion of the cells with a distinguishable cell wall disintegration and fully hyphae dispersal. There was no reactivity of Lasiodiplodia-antisera against mycelial extracts of Colletotrichum gloeosporioides, Phomopsis anardii and Pestalotiopsis guepinii. Following incubation of sections with the polyclonal antisera, the hyphae were intensely and regularly labeled. Rays, vessels and parenchyma cells were the preferred pathway for L. theobromae colonization. Artificial infection provides the information that the vascular cylinder is undoubtedly employed and used by the fungus for hyphae distribution. Immunofluorescence assay employed in situ was applied and the polyclonal antisera produced was able to recognize the fungus and proved to be a sensitive technique to detect it. 相似文献
34.
C Rodríguez-García A Oliva R M Ortu?o V Branchadell 《Journal of the American Chemical Society》2001,123(25):6157-6163
The reaction of diazomethane with ethylene in the presence of palladium diformate has been studied through density functional calculations. Several mechanistic paths leading to the formation of cyclopropane have been studied. The results obtained show that the reaction of palladium diformate with diazomethane is more favorable than the reaction with ethylene. The reaction with diazomethane may lead to two different isomeric complexes: a methylene-inserted complex and a palladium-carbene complex. Insertion of methylene is the most favorable process, but the resulting complex is not suitable for cyclopropanation. The reaction with two additional diazomethane molecules makes the formation of the bismethylene-inserted palladium-carbene complex favorable. Attack of ethylene on this palladium-carbene complex leads to the formation of cyclopropane. 相似文献
35.
We present a refinement ofthe bounded modified realizability which provides both upper and lower bounds for witnesses. Our interpretation is based on a generalisation of Howard/Bezem's notion of strong majorizability. We show how the bounded modified realizability coincides with (a weak version of) our interpretation in the case when least elements exist (e.g. natural numbers). The new interpretation, however, permits the extraction of more accurate bounds, and provides an ideal setting for dealing directly with data types whose natural ordering is not well‐founded (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
36.
M. Ramos Suzarte N. Rodríguez J. P. Oliva N. Iznaga A. Perera A. Morales N. Gonzalez O. Torres T. Rodríguez 《Journal of Radioanalytical and Nuclear Chemistry》1999,240(2):499-503
Monoclonal antibody ior egf/r3 is a IgG2a, recognizes the epidermal growth factor receptor. The aim of the present work was
to evaluate the diagnostic efficacy of the99mTc-labeled ior egf/r3 for the detection of epithelial tumors, its metastasis and its recurrences. The sensitivity by organs
was: brain 100%, diegestive tract 90%, head and neck 89%, lung 84% and breast 79%. The overall sensitivity, specificity, accuracy,
positive predictive value and negative predictive value of the immunoscintigraphic imaging were 84.1%, 100%, 86.5%, 100% and
52.4%, respectively. Immunoscintigraphy with99mTc-ior egf/r3 is useful for the diagnosis and follow-up of epithelial tumors. 相似文献
37.
Vladimir R. Rosenfeld Douglas J. Klein Josep M. Oliva 《Journal of mathematical chemistry》2012,50(7):2012-2022
Various sorts of isomer enumeration problems are addressed in the context of polycarboranes, with special illustrative focus on the case of dicarboranes, for which then various numerical results are given. A systematic and general Pólya-theoretic methodology is used to make the computations, including some new techniques being applicable to a wide range of nano-structures built from a framework of like local subunits. 相似文献
38.
39.
We propose a structural credit risk model for consumer lending using option theory and the concept of the value of the consumer’s reputation. Using Brazilian empirical data and a credit bureau score as proxy for creditworthiness we compare a number of alternative models before suggesting one that leads to a simple analytical solution for the probability of default. We apply the proposed model to portfolios of consumer loans introducing a factor to account for the mean influence of systemic economic factors on individuals. This results in a hybrid structural-reduced-form model. And comparisons are made with the Basel II approach. Our conclusions partially support that approach for modelling the credit risk of portfolios of retail credit. 相似文献
40.
Aurora Molinari Alfonso Oliva Marlene Arismendi Elizabeth Imbarack Cristian Glvez Javier Maldonado Arturo San Feliciano 《Journal of heterocyclic chemistry》2015,52(2):620-622
New fused pyrazolo‐1,4‐naphthoquinones were prepared from the reaction of hydrazines with 6‐(4‐methyl‐3‐pentenyl)‐1,4‐naphthoquinone. The reaction was extended to hydroxylamine to afford the corresponding isoxazolo‐1,4‐napthoquinone compound. 相似文献