53 research outputs found

    CUANTIFICACIÓN DE T 514 (PEROXISOMICINA A1) EN DOS PLANTAS DEL GÉNERO KARWINSKIA

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    Quantification of T 514 (peroxisomicineA1), a dimeric hydroxyanthracenone with potential antineoplasic effect is describedwhich was accomplished in two species ofgenus Karwinskia, collected in differenlocations of Mexico. The best source forthe extraction of this compound proved tobe Karwinskia parvifolia. This species wascollected in Sinaloa and Sonora; the resultsshowed a high amount of peroxisomicineA1, scarce stational variation and thepresence of a few number of secondarymetabolites which could interfere with theprocedure of extraction and purification.Se describe la cuantifiación de T 514 operoxisomicina A1, posible agenteantineoplásico, en dos plantas del géneroKarwinskia, obtenidas en distintas regiones de México. La mejor fuente de extracción de este compuesto resultó ser K.parvifolia, proveniente de Sinaloa y Sonora, por su alto contenido del compuesto encuestión, su escasa variabilidad estacionaly la presencia de pocas sustanciasinterferentes que pudieran complicar elprocedimiento de extracción y purificación

    Una nueva estrategia heurística para el problema de Bin Packing

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    ResumenEl problema de Bin Packing (BPP) es NP-duro, por lo que un método exacto para resolver instancias del BPP requiere un gran número de variables y demasiado tiempo de ejecución. En este trabajo se propone una nueva estrategia heurística para resolver instancias del BPP en donde se garantiza la solución óptima. La estrategia propuesta incluye el uso de un nuevo modelo exacto basado en arcos de flujo. En el modelo propuesto, el número de variables se redujo asignando objetos en contenedores. Adicionalmente se incluye una heurística que mediante el preprocesado de la instancia permite reducir su tamaño y con ello el espacio de búsqueda del algoritmo de solución. Para validar el enfoque propuesto, se realizaron experimentos usando los conjuntos de prueba hard28, 53nirup, bin1data, uniform, triplets y subconjuntos de otras instancias, todos ellos conocidos en el estado del arte. Los resultados muestran que empleando nuestro enfoque es posible encontrar la solución óptima de todas las instancias de prueba. Además, el tiempo de ejecución se redujo en relación con lo reportado por el modelo basado en arcos de flujo. Las reducciones de tiempo fueron de 19.7 y 43% para los conjuntos 53nirup y hard28, respectivamente.AbstractThe Bin Packing problem (BPP) is NP-hard, the use of exact methods for solving BPP instances require a high number of variables and therefore a high computational cost. In this paper a new heuristic strategy for solving the BPP instances, which guarantees obtain optimal solutions, is proposed. The proposed strategy includes the use of a new model based on flow arcs. In the proposed model, the number of variables was reduced by previous allocation of objects in bins. Additionally, our approach includes a heuristic that allows reducing the instance size and thereby the solution algorithm search space. To validate the proposed approach, experiments were performed using the test sets hard28, 53nirup, bin1data and falkenauer, all of them well known in the state of the art. The results show that it using our approach is possible to find the optimal solution for all test set. Also, the execution time was reduced in regard the reported time obtained by using the flow arc model. Time reductions were up to 19.7 and 43% for 53nirup and hard28 test set, respectively

    Antifungal evaluation of TiO2 nanoparticles that inhibit Fusarium solani in African oil palm

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    The ability of titanium dioxide nanoparticles (TiO2 NPs) to attenuate and control several microorganisms was studied, especially for a disease that affects the health and productiveness of crops. For this purpose, the antifungal capacity of TiO2 nanoparticles obtained from two synthesis procedures was evaluated: the first procedure involved green chemistry using an aqueous extract prepared from African palm oil (Elaeis guineensis Jacq.) leaves; the second procedure followed the Pechini sol-gel method. The nanoparticles obtained by the green chemistry method and the Pechini sol-gel technique had average sizes of 14.60±0.44 nm and 12.30±0.54 nm as determined by scanning electron microscopy (SEM), respectively. The antifungal properties of TiO2 NPs were evaluated on the fungus Fusarium solani Mart. isolated on Sabouraud culture medium. A factorial experimental design was implemented with two variables: (1) exposure time ranging from 24, 48, and 72 h; (2) nanoparticle concentration between 100 and 400 mg L-1. All measurements were performed in quintuplicate. The results show that the TiO2 nanoparticles synthesized by the Pechini method inhibited the fungus by 96.16±0.85% with a nanoparticle concentration of 400 mg L-1, while the TiO2 nanoparticles obtained from the green chemistry method generated a high inhibitory activity of approximately 98.51±0.02% at the four experimental concentrations

    Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

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    A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

    A multi-country test of brief reappraisal interventions on emotions during the COVID-19 pandemic.

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    The COVID-19 pandemic has increased negative emotions and decreased positive emotions globally. Left unchecked, these emotional changes might have a wide array of adverse impacts. To reduce negative emotions and increase positive emotions, we tested the effectiveness of reappraisal, an emotion-regulation strategy that modifies how one thinks about a situation. Participants from 87 countries and regions (n = 21,644) were randomly assigned to one of two brief reappraisal interventions (reconstrual or repurposing) or one of two control conditions (active or passive). Results revealed that both reappraisal interventions (vesus both control conditions) consistently reduced negative emotions and increased positive emotions across different measures. Reconstrual and repurposing interventions had similar effects. Importantly, planned exploratory analyses indicated that reappraisal interventions did not reduce intentions to practice preventive health behaviours. The findings demonstrate the viability of creating scalable, low-cost interventions for use around the world

    Measurements of top-quark pair differential cross-sections in the eμe\mu channel in pppp collisions at s=13\sqrt{s} = 13 TeV using the ATLAS detector

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    Measurement of the charge asymmetry in top-quark pair production in the lepton-plus-jets final state in pp collision data at s=8TeV\sqrt{s}=8\,\mathrm TeV{} with the ATLAS detector

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    Search for single production of vector-like quarks decaying into Wb in pp collisions at s=8\sqrt{s} = 8 TeV with the ATLAS detector

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    Measurement of the W boson polarisation in ttˉt\bar{t} events from pp collisions at s\sqrt{s} = 8 TeV in the lepton + jets channel with ATLAS

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