1,067 research outputs found

    Genetic basis of octanoic acid resistance in drosophila sechellia: functional analysis of a fine-mapped region

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    Masters thesisDrosophila sechellia is a species of fruit fly endemic to the Seychelles islands, which are located northeast of Madagascar off the coast of Africa. Unlike its generalist sister species D. simulans and D. mauritiana, and their closest relative D. melanogaster, D. sechellia evolved to specialize on a single plant species, Morinda citrifolia. Specialization on M. citrifolia is surprising because the fruit of the plant contains toxic compounds, primarily octanoic acid (OA), that are lethal to all Drosophila species except D. sechellia. Although the ecological and behavioral adaptations to this toxic fruit are known, the genetic basis for the evolutionary changes in OA resistance is not. Prior work showed that a genomic region on chromosome 3R, containing 18 genes, contributes to OA tolerance. To determine which gene(s) in this region might be involved in the evolution of OA resistance, I knocked-down expression of each gene in D. melanogaster with RNA interference (RNAi) (i) ubiquitously throughout development, (ii) during the adult stage, and (iii) within specific tissues in D. melanogaster. RNAi knockdown flies were tested for resistance to OA using the mixed effects Cox regression model. I found that knock-down of three neighboring genes, Osiris 6, Osiris 7, and Osiris 8, increased OA sensitivity. Tissue specific knockdowns, however, showed that decreasing expression of these genes in the fat body and salivary glands increases OA tolerance. I show that both Osi6/7 are highly expressed during the first 24 hours of development and that exposure to different stressors induces expression in adults. Although Osi6/7 have no coding change, RNA-seq data shows derived lower expression of these genes in D. sechellia; Osi8 has two derived coding changes in D. sechellia. This study sheds light on the genetic basis of ecological adaptation to a toxic host within Drosophila, and insect-host specialization more broadly.http://deepblue.lib.umich.edu/bitstream/2027.42/113257/1/MSThesis2015_AndradeLopez.pdf-1Description of MSThesis2015_AndradeLopez.pdf : Thesis tex

    Fracture test of a Gothic ribbed vault

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    A Gothic ribbed vault has been built at the School of Architecture of Madrid in order to investigate the construction complexities of this kind of vaults. The ribbed vault is described in the manuscript of Alonso de Vandelvira, and its shape was reconstructed making using the drawings this architect from the 16th century. The fracture test was carried on by loading the central keystone of the vault until its collapse took place. The experiment was filmed and by doing so, it was possible to observe the failure mechanism of the vault. At the same time, it was interesting to compare this collapse experience with the results obtained using two different me-thods. First, a stability calculation was carried out through graphic statics, and secondly a calcu-lation was performed using the rigid-block analysis method. The focus of this paper is to show and analyze the results of both studies

    Non-perturbative Power Corrections to Ghost and Gluon Propagators

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    We study the dominant non-perturbative power corrections to the ghost and gluon propagators in Landau gauge pure Yang-Mills theory using OPE and lattice simulations. The leading order Wilson coefficients are proven to be the same for both propagators. The ratio of the ghost and gluon propagators is thus free from this dominant power correction. Indeed, a purely perturbative fit of this ratio gives smaller value (270\simeq 270MeV) of \Lambda_{\ms} than the one obtained from the propagators separately(320\simeq 320MeV). This argues in favour of significant non-perturbative 1/q2\sim 1/q^2 power corrections in the ghost and gluon propagators. We check the self-consistency of the method.Comment: 14 pages, 4 figures; replaced with revised version, to appear in JHE

    Electrospraying assisted by pressurized gas as an innovative high-throughput process for the microencapsulation and stabilization of docosahexaenoic acid-enriched fish oil in zein prolamine

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    [EN] Zein, a prolamine obtained from maize, was employed to encapsulate a fish oil highly enriched with docosahexaenoic acid (DHA) by an innovative process termed electrospraying assisted by pressurized gas (EAPG). This technology combines high electric voltage with pneumatic spray to yield a high-throughput encapsulation process. Semi-spherical zein flowable capsules with mean sizes of 1.4 mu m containing the DHA-enriched fish oil were produced by EAPG from inert ethanol solutions at room conditions, presenting a high encapsulation efficiency. The oxidative stability tests carried out in the zein microcapsules obtained by EAPG showed that the DHA-enriched fish oil was efficiently protected over storage time. Sensory tests were also performed on fortified reconstituted milk with the freshly prepared zein/DHA-enriched fish oil microcapsules, suggesting negligible oxidation effects after 45 days. The results described herein indicate that EAPG is a promising innovative high-throughput electrospraying-based methodology for the encapsulation of bioactives and, therefore, the resultant DHA-enriched fish oil containing microcapsules can be industrially applied for the formulation of fortified foods. Industrial relevance: An innovative process, termed electrospraying assisted by pressurized gas (EAPG), is herein originally presented as a novel encapsulation methodology. This technology is based on the combination of high voltage and pneumatic spray, allowing the formation of microcapsules at room temperature conditions. Thus, EAPG shows a great deal of potential to encapsulate nutraceuticals and other bioactives that are sensitive to thermal degradation and/or oxidation. The resultant bioactive-containing capsules can be, thereafter, applied to develop novel fortified food products.The authors would like to thank the Spanish Ministry of Economy and Competitiveness (MINECO) project AGL2015-63855-C2-1-R and to the H2020 EU project YPACK (reference number 773872) for funding.Busolo, M.; Torres-Giner, S.; Prieto, C.; Lagaron, JM. (2019). Electrospraying assisted by pressurized gas as an innovative high-throughput process for the microencapsulation and stabilization of docosahexaenoic acid-enriched fish oil in zein prolamine. Innovative Food Science & Emerging Technologies. 51:12-19. https://doi.org/10.1016/j.ifset.2018.04.007S121951Aghbashlo, M., Mobli, H., Madadlou, A., & Rafiee, S. (2012). The correlation of wall material composition with flow characteristics and encapsulation behavior of fish oil emulsion. Food Research International, 49(1), 379-388. doi:10.1016/j.foodres.2012.07.031Anwar, S. H., & Kunz, B. (2011). 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    Stress distribution in orthodontic mini-implants

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    O objetivo deste trabalho foi avaliar a distribuição de tensões na resina em contato com os filetes de roscas de mini-implantes cilíndricos e cônicos, submetidos à carga lateral e torção de inserção. Um modelo fotoelástico foi confeccionado com gelatina transparente, para simular o osso alveolar. O modelo foi observado com um polariscópio plano e fotografado antes e após a ativação dos mini-implantes com força lateral e de inserção. A aplicação de cargas laterais provocou momentos fletores nos mini-implantes, aparecimento de franjas isocromáticas ao longo dos filetes do corpo dos mini-implantes e no ápice. Quando foi aplicado o torque de inserção, verificou-se a concentração de tensões próxima ao ápice. Concluiu-se que: (1) o mini-implante cilíndrico apresentou maior concentração de tensões no ápice, e (2) o mini-implante cônico apresentou maior concentração de tensões nos filetes de rosca apicais.The objective of this study was to evaluate the stress distribution in the resin in contact with the spirals of cylindrical and conical mini-implants, when submitted to lateral load and insertion torsion. A photoelastic model was fabricated using transparent gelatin to simulate the alveolar bone. The model was observed with a plane polariscope and photographically recorded before and after activation of the two screws with a lateral force and torsion. The lateral force application caused bending moments on both mini-implants, with the uprising of fringes or isochromatics, characteristics of stresses, along the threads of the mini-implants and in the apex. When the torsion was exerted in the mini-implants, a great concentration of stress upraised close to the apex. The conclusion was that, comparing conical with cylindrical mini-implants under lateral load, the stresses were similar on the traction sides. The differences appear (1) on the apex, where the cylindrical mini-implant showed a greater concentration of stress, and (2) along the spirals, in the compression side, where the conical mini-implant showed a greater concentration of stress. The greater part of the stress produced by both mini-implants, after torsion load in insertion, were concentrated on the apex. With the cylindrical mini-implant, the greater concentration of tension was close to the apex, while with the conical one, the stresses were distributed along a greater amount of apical threads

    Comportamiento mecánico de la aleación W+1%Y2O3 en función de la atmósfera y la temperatura

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    Mediante ensayos de flexión en tres puntos se compara y evalúa el comportamiento mecánico de la aleación W- 1wt%Y2O3 con el W puro fabricados ambos mediante HIP. Se ha obtenido la tenacidad de fractura, la resistencia a flexión y el límite elástico en atmósfera oxidante y de vacío en un intervalo de temperaturas comprendido entre -196 ºC, ensayos de inmersión en nitrógeno líquido, y 1200 ºC. Previamente, se ha medido la densidad, la dureza mediante ensayos Vickers y el módulo de elasticidad dinámico de los materiales. Además, la dureza y el módulo de elasticidad se han comparado con los obtenidos mediante ensayos instrumentados de nanoindentación. Finalmente se ha realizado un pequeño estudio de las superficies de fractura de las muestras ensayadas mediante microscopía electrónica de barrido para poder relacionar el modo de rotura de los materiales y las propiedades mecánicas macroscópicas con los micromecanismos de fallo involucrados en función de la temperatura

    The biomass based electricity generation potential of the Province of Cienfuegos, Cuba

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    By 2013, the province of Cienfuegos in Cuba consumed about 5165 GWh of primary energy, of which an estimated 60 % was used to produce 767 GWh of electricity. 29 % of the primary energy was obtained from renewable fuel, and only less than 5 % of the biomass energy, was used to produce about 27 GWh of biomass based electricity. This study proposes and assesses opportunities to produce electricity from biomass in the sugar industry of the province. The scenarios considered include: upgrading the agricultural yield of sugarcane, producing energy cane and combusting it after the sugarcane milling season, combusting the filter cake, combusting marabu (Dichrostachys cinerea, a bush tree considered a plague in Cuba) after the sugarcane milling season, and updating the electricity generation technology. Results are given for the different scenarios and it is shown that a combined scenario, including upgrading agricultural yield of sugarcane, upgrading electricity generation technology, combusting filter cake, and producing energy cane to generate electricity after the sugarcane milling season, thus allowing to use the generation units in sugar factories during 8000 h per year affords a potential production of 1150 GWh of electricity, 50 % more than consumed in Cienfuegos province in 2013. © 2016, Springer Science+Business Media Dordrecht

    Mechanical characterisation of tungsten-1wt.% yttrium oxide as a function of temperature and atmosphere

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    This study evaluates the mechanical behaviour of an Y2O3-dispersed tungsten (W) alloy and compares it to a pure W reference material. Both materials were processed via mechanical alloying (MA) and subsequent hot isostatic pressing (HIP). We performed non-standard three-point bending (TPB) tests in both an oxidising atmosphere and vacuum across a temperature range from 77 K, obtained via immersion in liquid nitrogen, to 1473 K to determine the mechanical strength, yield strength and fracture toughness. This research aims to evaluate how the mechanical behaviour of the alloy is affected by oxides formed within the material at high temperatures, primarily from 873 K, when the materials undergo a massive thermal degradation. The results indicate that the alloy is brittle to a high temperature (1473 K) under both atmospheres and that the mechanical properties degrade significantly above 873 K. We also used Vickers microhardness tests and the dynamic modulus by impulse excitation technique (IET) to determine the elastic modulus at room temperature. Moreover, we performed nanoindentation tests to determine the effect of size on the hardness and elastic modulus; however, no significant differences were found. Additionally, we calculated the relative density of the samples to assess the porosity of the alloy. Finally, we analysed the microstructure and fracture surfaces of the tested materials via field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). In this way, the relationship between the macroscopic mechanical properties and micromechanisms of failure could be determined based on the temperature and oxides forme

    Application surface of CPT, an advanced DInSAR displacement near Itoiz dam, Navarra, Spain

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    Itoiz reservoir is located in Navarra, northern Spain, being a newly constructed gravity dam that stores the water from the Irati and the Urrobi rivers. The dam has a total height of 121 m, a total length of 525 m and a maximum water storage volume of 410 hm3. The aim of this work is to study the surface displacement field during the impoundment of the Itoiz water reservoir. Orbital SAR Differential Interferometry (DInSAR) techniques have been proven to be a useful and powerful tool in tectonic areas for surveying subtle surface deformations over several years related to geodynamic phenomena. An advanced DInSAR observation technique, Coherent Pixel Technique (CPT), has been applied to study the existence of deformation in the dam area in order to obtain mean velocities and time series of deformation. We have studied the applicability of this technique to study the surface displacement field during the impoundment of the Itoiz water reservoir. Specifically, we focus on the analysis of the stability of the left slope of the reservoir. We have used ERS and ENVISAT descending and ascending images concerning to the 1992-2008 and 2003-2008 periods respectively. We compare the observation results with the displacement induced by water loading obtained using a theoretical model
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