2,616 research outputs found

    Histochemical data on the skin mucous cells during the development of the trout [Translation from: Bollettino della Societa Italiana di Biologia Sperimentale 45, 1273-1276, 1969]

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    In the skin of Salmo irideus the production of mucus is due to one type of cell specialized as a mucus cell. The histochemical research presented in this paper describes the mucous cells of Salmo irideus and demonstrates observable variation in such cells during the fish's development

    Modelización de la inundación química de yacimientos petrolíferos

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    Se desarrollan dos modelos que predicen el petróleo recuperable mediante la inyección de sustancias químicas. Ambos consideran dos fases (acuosa u oleosa) y tres componentes (agua, petróleo y especie química). El flujo es horizontal, unidimensional e incompresible. La roca tiene propiedades uniformes y puede adsorber la sustancia química. Se supone equilibrio termodinámico a través de las fases. La dispersión y los gradientes de presión capilar son despreciables y además la composición de inyección es constante. Los modelos están gobernados por un sistema de ecuaciones diferenciales parciales no lineales: la ecuación de continuidad de cada componente y la ecuación de Darcy para el flujo bifásico. En el modelo más riguroso se resuelve el sistema de ecuaciones aplicando una técnica en diferencias finitas. En el modelo más simple se adicionan restricciones con el objeto de hallar soluciones analíticas. El objetivo de este trabajo es analizar la utilidad y las limitaciones del modelo simple. Se concluye que si bien las restricciones adicionadas no responden a la realidad, el modelo simple es capaz de representar los mecanismos físicos de desplazamientos más importantes y permite obtener una primera aproximación del petróleo recuperable que es el valor máximo de la recuperación verdadera.Peer Reviewe

    A Relaxed Interior Point Method for Low-Rank Semidefinite Programming Problems with Applications to Matrix Completion

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    A new relaxed variant of interior point method for low-rank semidefinite programming problems is proposed in this paper. The method is a step outside of the usual interior point framework. In anticipation to converging to a low-rank primal solution, a special nearly low-rank form of all primal iterates is imposed. To accommodate such a (restrictive) structure, the first order optimality conditions have to be relaxed and are therefore approximated by solving an auxiliary least-squares problem. The relaxed interior point framework opens numerous possibilities how primal and dual approximated Newton directions can be computed. In particular, it admits the application of both the first- and the second-order methods in this context. The convergence of the method is established. A prototype implementation is discussed and encouraging preliminary computational results are reported for solving the SDP-reformulation of matrix-completion problems

    Metastatic melanoma cells with BRAF G469A mutation: nab‑paclitaxel better than vemurafenib?

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    Purpose BRAF G469A is a missense mutation within exon 11 of the BRAF gene resulting in a constitutively activated enzyme frequently associated with MAP kinase cascade signaling activation. No evidence currently exists about its role in determining sensitivity/resistance to BRAF inhibitors, utilized in the treatment of patients carrying BRAF V600 mutations, and to chemotherapy. The newly established metastatic melanoma (MM) cell line MO-1 was characterized for its sensitivity to vemurafenib and nabpaclitaxel, both already utilized for the treatment of MM. Methods All analyses were carried out by comparing results with those found in MM cells wild type for BRAF or mutated in V600. In addition, cellular effectors were investigated by ELISA kits, western blotting and flow cytometry. Results The exposure to vemurafenib inhibited MO-1 cell proliferation at concentrations similar to those obtained in vemurafenib-resistant melanoma models, and an explanation of this sensitivity is the strong activation of Erk1/2 . and the low expression of MITF. Nab-paclitaxel strongly reduced proliferation of MO-1 cells perhaps for the very low expression level of PMEL17, transcriptionally regulated by MITF and negatively involved in determining sensitivity to taxanes. Conclusions Thus, the mutation BRAF G469A in MM might be related to a weak effectiveness of therapy with BRAF inhibitors and a promising therapeutic approach may be with nab-paclitaxel

    New updates of incomplete LU factorizations and applications to large nonlinear systems

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    Abstract In this paper, we address the problem of preconditioning sequences of large sparse nonsymmetric systems of linear equations and present two new strategies to construct approximate updates of factorized preconditioners. Both updates are based on the availability of an incomplete LU (ILU) factorization for one matrix of the sequence and differ in the approximation of the so-called ideal updates. The first strategy is an approximate diagonal update of the ILU factorization; the second strategy relies on banded approximations of the factors in the ideal update. The efficiency and reliability of the proposed preconditioners are shown in the solution of nonlinear systems of equations by preconditioned inexact Newton-Krylov methods. Matrix-free implementations of the updating strategy are provided and numerical experiments are carried out on application problems

    Zelus renardii Roaming in Southern Italy

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    This study collects data from the literature and updates our Zelus renardii Kolenati, 1856 (Leafhopper Assassin Bug, LAB) prey knowledge. The literature consists of ca. 170 entries encompassing the years 1856 to 2021. This reduviid originated in the Nearctic region, but has entered and acclimatised in many Mediterranean countries. Our quantitative predation experiments—in the laboratory on caged plants plus field or environmental observations—confirm that LAB prefers a selected array of prey. Laboratory predation tests on living targets (Hemiptera, Coleoptera, Diptera, and Hymenoptera) agree with the literature. Zelus renardii prefers comparatively large, highly mobile, and readily available prey. LAB preferences on available hemipterans targets suggest that Zelus renardii is a good inundative biocontrol agent for Xylella fastidiosa pauca ST53 infections. LAB also prey on other important olive pests, such as Bactrocera oleae. Therefore, Zelus renardii is a major integrated pest management (IPM) component to limit Xylella fastidiosa pandemics and other pest invasions
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