87 research outputs found
A forward-backward splitting algorithm for the minimization of non-smooth convex functionals in Banach space
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
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
Lepidópteros ocorrentes na safra e entressafra da soja no sudoeste do Mato Grosso.
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
Pearl Millet: a green bridge for Lepidopteran Pests.
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
Convergence and Perturbation Resilience of Dynamic String-Averaging Projection Methods
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
Egg parasitoids of Edessa meditabunda (Fabricius) (Pentatomidae) in lettuce crop
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
Smearing of Observables and Spectral Measures on Quantum Structures
An observable on a quantum structure is any -homomorphism of quantum
structures from the Borel -algebra of the real line into the quantum
structure which is in our case a monotone -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
-subalgebra of the effect algebra, and we prove that for every element
of the effect algebra there is its spectral measure
Sharp and fuzzy observables on effect algebras
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
Sparse Regularization with Penalty Term
We consider the stable approximation of sparse solutions to non-linear
operator equations by means of Tikhonov regularization with a subquadratic
penalty term. Imposing certain assumptions, which for a linear operator are
equivalent to the standard range condition, we derive the usual convergence
rate of the regularized solutions in dependence of the noise
level . Particular emphasis lies on the case, where the true solution
is known to have a sparse representation in a given basis. In this case, if the
differential of the operator satisfies a certain injectivity condition, we can
show that the actual convergence rate improves up to .Comment: 15 page
Evaluation of Biologically Active Compounds from Calendula officinalis Flowers using Spectrophotometry
<p>Abstract</p> <p>Background</p> <p>This study aimed to quantify the active biological compounds in <it>C. officinalis </it>flowers. Based on the active principles and biological properties of marigolds flowers reported in the literature, we sought to obtain and characterize the molecular composition of extracts prepared using different solvents. The antioxidant capacities of extracts were assessed by using spectrophotometry to measure both absorbance of the colorimetric free radical scavenger 2,2-diphenyl-1-picrylhydrazyl (DPPH) as well as the total antioxidant potential, using the ferric reducing power (FRAP) assay.</p> <p>Results</p> <p>Spectrophotometric assays in the ultraviolet-visible (UV-VIS) region enabled identification and characterization of the full range of phenolic and flavonoids acids, and high-performance liquid chromatography (HPLC) was used to identify and quantify phenolic compounds (depending on the method of extraction). Methanol ensured more efficient extraction of flavonoids than the other solvents tested.</p> <p>Antioxidant activity in methanolic extracts was correlated with the polyphenol content.</p> <p>Conclusions</p> <p>The UV-VIS spectra of assimilator pigments (e.g. chlorophylls), polyphenols and flavonoids extracted from the <it>C. officinalis </it>flowers consisted in quantitative evaluation of compounds which absorb to wavelengths broader than 360 nm.</p
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