170 research outputs found

    A forward-backward splitting algorithm for the minimization of non-smooth convex functionals in Banach space

    Full text link
    We consider the task of computing an approximate minimizer of the sum of a smooth and non-smooth convex functional, respectively, in Banach space. Motivated by the classical forward-backward splitting method for the subgradients in Hilbert space, we propose a generalization which involves the iterative solution of simpler subproblems. Descent and convergence properties of this new algorithm are studied. Furthermore, the results are applied to the minimization of Tikhonov-functionals associated with linear inverse problems and semi-norm penalization in Banach spaces. With the help of Bregman-Taylor-distance estimates, rates of convergence for the forward-backward splitting procedure are obtained. Examples which demonstrate the applicability are given, in particular, a generalization of the iterative soft-thresholding method by Daubechies, Defrise and De Mol to Banach spaces as well as total-variation based image restoration in higher dimensions are presented

    Egg parasitoids of Edessa meditabunda (Fabricius) (Pentatomidae) in lettuce crop

    Get PDF
    Egg parasitoids of Edessa meditabunda (Fabricius) (Pentatomidae) in lettuce crop. This study evaluated the occurrence of parasitoids in eggs of the stink bug, Edessa meditabunda (Fabricius, 1794) (Heteroptera, Pentatomidae) found on lettuce crop in Mato Grosso State, Brazil. Samples were collected in the vegetable garden "Cheiro Verde", in the municipality of Tangará da Serra, in curly lettuce. A bed of lettuce was selected randomly, where the eggs of E. meditabunda were collected. Five-hundred and seventy eight eggs of E. meditabunda were collected, 86.3% of them parasitized by Telenomus podisi Ashmead, 1893 (Hymenoptera, Platygastridae), Trissolcus urichi Crawford, 1913 (Hymenoptera, Platygastridae) and Neorileya albipes Girault, 1913 (Hymenoptera, Eurytomidae), representing respectively 57.0%, 38.2% and 4.8% of the emerged individuals. This is the first record of these three species parasitizing eggs of E. meditabunda in lettuce.Facultad de Ciencias Naturales y Muse

    Pearl Millet: a green bridge for Lepidopteran Pests.

    Get PDF
    Abstract: This study evaluated the occurrence of lepidopteran pests on millet cultivated in off-season in the state of Mato Grosso, Brazil. Larvae were collected from May to July 2013 in an area of 145 hectares located in Tangará da Serra, MT. After being collected, caterpillars were kept in the laboratory and fed an artificial diet until the pupal stage. After emergence, adults were dry mounted, identified, and deposited in the entomological collection of Embrapa Cerrados, Planaltina, Distrito Federal, Brazil. Adults obtained from 117 caterpillars were identified as Mocis latipes (Guenée), Spodoptera frugiperda (J.E. Smith), Helicoverpa armigera (Hübner), H. zea (Boddie), Mythimna (Pseudaletia) sequax Franclemont, Urbanus proteus (Linnaeus), and Leucania latiuscula Herrich-Schäffer. This study describes the first record of lepidopteran pests on millet plants in the state of Mato Grosso, and the incidence of lepidopterans in the system that uses millet as cover crop represents a risk of the occurrence of insect pests on subsequent crops on the straw of this grass

    Local Analysis of Inverse Problems: H\"{o}lder Stability and Iterative Reconstruction

    Full text link
    We consider a class of inverse problems defined by a nonlinear map from parameter or model functions to the data. We assume that solutions exist. The space of model functions is a Banach space which is smooth and uniformly convex; however, the data space can be an arbitrary Banach space. We study sequences of parameter functions generated by a nonlinear Landweber iteration and conditions under which these strongly converge, locally, to the solutions within an appropriate distance. We express the conditions for convergence in terms of H\"{o}lder stability of the inverse maps, which ties naturally to the analysis of inverse problems

    Lepidópteros ocorrentes na safra e entressafra da soja no sudoeste do Mato Grosso.

    Get PDF
    Esta pesquisa verificou a ocorrência de lepidópteros desfolhadores durante a safra e entressafra da soja na região sudoeste do estado de Mato Grosso. O estudo foi conduzido na fazenda Aparecida da Serra (14°18'59"S, 57°45'16"W) (14°20'23"S, 57°42'39"W), localizada entre os municípios de Tangará da Serra e Nova Marilândia. No cultivo da soja (TMG 132RR), as coletas foram na safra 2012/13, em um talhão de 50 ha. Foram avaliados quatro transectos contendo 10 estacas cada, distantes 50 metros entre si, totalizando 40 pontos de coleta. Durante a entressafra, as avaliações ocorreram em um talhão de 145 ha contendo milheto (ADR 7010) e próximo ao cultivo de soja anterior. Nesse, foram estabelecidos 12 pontos de coleta, distribuídos em um transecto, cuja distância foi de 67 metros entre cada ponto, e de 134 m a cada quatro pontos. Na soja, 10 coletas foram feitas semanalmente (dezembro a fevereiro) com pano-de-batida, e no milheto, oito coletas quinzenalmente (maio a julho) por metro linear, além de coleta manual, por procura ativa, em ambos. O manejo utilizado pelo produtor na soja foi com defensivos químicos e, no milheto, não houve aplicação de produtos. Os lepidópteros coletados na soja foram Chrysodeixis includens Walker), Spodoptera sp., Heliothis virescens (Fabricius) e Anticarsia gemmatalis Hübner. No milheto ocorreram os noctuídeos Mocis latipes (Guenée), Spodoptera frugiperda (Smith), Helicoverpa sp., Helicoverpa armigera (Hübner), Mythimna sequax Franclemont, Helicoverpa zea (Boddie), Leucania latiuscula Herrich-Schäffer, o hesperíideo Urbanus proteus (Linnaeus), e um espécime de Geometridae. Conclui-se que o número de lepidópteros foi maior no milheto do que na soja, e, que exemplares da sub-família Heliothiinae e do gênero Spodoptera estiveram presentes durante os dois cultivos avaliados. Estes resultados contribuem para o conhecimento do complexo de insetos ocorrentes na safra e entressafra da soja e, potencialmente, para o manejo integrado de pragas

    Convergence and Perturbation Resilience of Dynamic String-Averaging Projection Methods

    Full text link
    We consider the convex feasibility problem (CFP) in Hilbert space and concentrate on the study of string-averaging projection (SAP) methods for the CFP, analyzing their convergence and their perturbation resilience. In the past, SAP methods were formulated with a single predetermined set of strings and a single predetermined set of weights. Here we extend the scope of the family of SAP methods to allow iteration-index-dependent variable strings and weights and term such methods dynamic string-averaging projection (DSAP) methods. The bounded perturbation resilience of DSAP methods is relevant and important for their possible use in the framework of the recently developed superiorization heuristic methodology for constrained minimization problems.Comment: Computational Optimization and Applications, accepted for publicatio

    Smearing of Observables and Spectral Measures on Quantum Structures

    Full text link
    An observable on a quantum structure is any σ\sigma-homomorphism of quantum structures from the Borel σ\sigma-algebra of the real line into the quantum structure which is in our case a monotone σ\sigma-complete effect algebras with the Riesz Decomposition Property. We show that every observable is a smearing of a sharp observable which takes values from a Boolean σ\sigma-subalgebra of the effect algebra, and we prove that for every element of the effect algebra there is its spectral measure

    Egg parasitoids of Edessa meditabunda (Fabricius) (Pentatomidae) in lettuce crop

    Get PDF
    Egg parasitoids of Edessa meditabunda (Fabricius) (Pentatomidae) in lettuce crop. This study evaluated the occurrence of parasitoids in eggs of the stink bug, Edessa meditabunda (Fabricius, 1794) (Heteroptera, Pentatomidae) found on lettuce crop in Mato Grosso State, Brazil. Samples were collected in the vegetable garden "Cheiro Verde", in the municipality of Tangará da Serra, in curly lettuce. A bed of lettuce was selected randomly, where the eggs of E. meditabunda were collected. Five-hundred and seventy eight eggs of E. meditabunda were collected, 86.3% of them parasitized by Telenomus podisi Ashmead, 1893 (Hymenoptera, Platygastridae), Trissolcus urichi Crawford, 1913 (Hymenoptera, Platygastridae) and Neorileya albipes Girault, 1913 (Hymenoptera, Eurytomidae), representing respectively 57.0%, 38.2% and 4.8% of the emerged individuals. This is the first record of these three species parasitizing eggs of E. meditabunda in lettuce.Facultad de Ciencias Naturales y Muse

    Sharp and fuzzy observables on effect algebras

    Full text link
    Observables on effect algebras and their fuzzy versions obtained by means of confidence measures (Markov kernels) are studied. It is shown that, on effect algebras with the (E)-property, given an observable and a confidence measure, there exists a fuzzy version of the observable. Ordering of observables according to their fuzzy properties is introduced, and some minimality conditions with respect to this ordering are found. Applications of some results of classical theory of experiments are considered.Comment: 23 page

    Sulfhydryl groups as targets of mercury toxicity

    Get PDF
    The present study addresses existing data on the affinity and conjugation of sulfhydryl (thiol; -SH) groups of low- and high-molecular-weight biological ligands with mercury (Hg). The consequences of these interactions with special emphasis on pathways of Hg toxicity are highlighted. Cysteine (Cys) is considered the primary target of Hg, and link its sensitivity with thiol groups and cellular damage. In vivo, Hg complexes play a key role in Hg metabolism. Due to the increased affinity of Hg to SH groups in Cys residues, glutathione (GSH) is reactive. The geometry of Hg(II) glutathionates is less understood than that with Cys. Both Cys and GSH Hg-conjugates are important in Hg transport. The binding of Hg to Cys mediates multiple toxic effects of Hg, especially inhibitory effects on enzymes and other proteins that contain free Cys residues. In blood plasma, albumin is the main Hg-binding (Hg2+, CH3Hg+, C2H5Hg+, C6H5Hg+) protein. At the Cys34 residue, Hg2+ binds to albumin, whereas other metals likely are bound at the N-terminal site and multi-metal binding sites. In addition to albumin, Hg binds to multiple Cys-containing enzymes (including manganese-superoxide dismutase (Mn-SOD), arginase I, sorbitol dehydrogenase, and δ-aminolevulinate dehydratase, etc.) involved in multiple processes. The affinity of Hg for thiol groups may also underlie the pathways of Hg toxicity. In particular, Hg-SH may contribute to apoptosis modulation by interfering with Akt/CREB, Keap1/Nrf2, NF-κB, and mitochondrial pathways. Mercury-induced oxidative stress may ensue from Cys-Hg binding and inhibition of Mn-SOD (Cys196), thioredoxin reductase (TrxR) (Cys497) activity, as well as limiting GSH (GS-HgCH3) and Trx (Cys32, 35, 62, 65, 73) availability. Moreover, Hg-thiol interaction also is crucial in the neurotoxicity of Hg by modulating the cytoskeleton and neuronal receptors, to name a few. However, existing data on the role of Hg-SH binding in the Hg toxicity remains poorly defined. Therefore, more research is needed to understand better the role of Hg-thiol binding in the molecular pathways of Hg toxicology and the critical role of thiols to counteract negative effects of Hg overload. Keywords: Apoptosis; Conjugates; Cysteine; Mercury; S-mercuration.R01 ES007331/ES/NIEHS NIH HHS/United States R01 ES010563/ES/NIEHS NIH HHS/United States R01 ES020852/ES/NIEHS NIH HHS/United StatesacceptedVersio
    corecore