1,798 research outputs found
Mantle dynamics and volcanism emplacement in the Azores
The Azores plateau is a triangular shaped topographic feature encompassing the boundary zone where three major
tectonic plates (EU, NU and NA) meet. The eastern side of the plateau is delimited by two major tectonic discontinuities:
the Mid Atlantic Ridge, and the Terceira Rift, a recently formed ultra-slow-spreading ridge. The origin
of the plateau is still under debate. One hypothesis argues that the plateau would have been formed by successive
NE jumps of the oblique spreading axis, where the present TR is the latest stage. Other hypotheses invoke the
northward jump of the Azores triple junction, during which the Azores region would have been transferred from
the Eurasian plate to the Nubian plate. For some authors, the presence of the Azores plume, a low seismic velocity
zone in the mantle beneath, is required to explain the observations: the anomalously shallow seafloor depth as well
as the geochemistry of the basaltic lavas erupted within the plateau. Here we use a highly resolved tomography
model to quantify the influence of this plume and the surrounding mantle.We model the convection pattern, the induced
dynamic topography and stresses, and compare them with the surface observations. The dynamic topography
shows two maxima: one northwest of St. Miguel, the other encompassing the Terceira, Graciosa, S. Jorge, Faial
and Pico islands. Both swells are approximately located on the Terceira Ridge. The convection pattern displays
two distinct upwelling towards these two groups of Islands. This may explain the difference in the geochemical
signatures, in particular the unique isotopic ratios observed in some lavas from S. Miguel. The stresses induced
by the underlying mantle convection are compared with the surface observations (topographic features, seismic and GPS velocities). The modeled and observed tresses fairly correlate west of our study area but their directions depart east
Relevant occupational health and safety risks in the Portuguese food processing industry
The Agrifood Industry is the largest Portuguese Industry, constituted mainly by micro, small and medium-sized enterprises (SMEs). It is noted that more than any other type of organization SMEs have their own specificities that make it particularly appropriate to develop tools to facilitate communication and knowledge sharing for employers and workers. To this extent, identifying critical success factors is the key to increase SMEs productivity. Likewise, Occupational Safety and Health (OSH) in SMEs have their own characteristics, which difficult the prevention strategies implementation and aggravate the problematic of work accidents. This study analyses a fieldwork in 60 food processing companies in Portugal, related to the dairy, meat processing, bakery and horticultural subsectors. The analysis of the results allowed to identify that, at the national and regional level, the main failures are concerned with (1) lack of risk assessments regarding occupational noise, lighting, thermal environment and vibrations; (2) safety signaling, the circulation ways are not identified with appropriate safety colors; (3) general lighting, with too many shade areas and finally (4) complementary presence of associated risks to falls at the same level, falling of objects, thermal burns, the use of machines and equipment, fire, mechanical, ergonomic hazards and incorrect body postures. This study assesses the most relevant occupational health and safety risks in the Portuguese food processing industry to contribute to the improvement of OSH management and prevention of work accidents.info:eu-repo/semantics/publishedVersio
Mechanical characterization of old chestnut beams
The main objective of this work is to evaluate, by non-destructive techniques, seven old
Chestnut beams. For that, after the geometric assessment and the detailed visual
inspection that allowed to strength grade the beams, a series of non-destructive tests was
setup. In a first step, non-destructive bending tests, under the elastic limit, were
performed to quantify the modulus of elasticity in bending (MoE) of the seven beams.
Then, ResistographÂź and PilodynÂź tests were done to assess the superficial decay and to
have a clearer idea of the voids dimensions. Then, two beams were tested in bending until
failure to evaluate the bending strength. In a second step, end parts were cut from the
beams, one per end of the beams, to perform ResistographÂź, PilodynÂź and ultrasound
tests, to quantify the density of the beams and to extract meso-specimens to be used in
tension parallel to the grain tests.Fundação de CiĂȘncia e Tecnologia (FCT), through project âSafety evaluation of timber structures
through non-destructive methods and stochastic analysisâ, PTDC/ECM/66527/2006RILEM TC 215 AST âIn-situ assessment of structural timberâ
Morphostructure of the Tore Seamount and evidences of recent tectonic activity (West Iberia Margin)
Applicability of extracts from Centaurea calcitrapa in ripening of bovine cheese
Aqueous extracts obtained from cell suspension cultures of Centaurea calcitrapa were used as proteolytic additive in the
manufacture of a commercial bovine cheese, coagulated with animal rennet and typically ripened for 28 d. The cheese was assessed in
comparison to standard cheese for two levels of addition of said extract, viz. 0.61 and 1.22mg of total protein mL~1. The qualitative
and quantitative evolutions of the nitrogen fractions were monitored in the experimental cheeses throughout the whole ripening
period. In general, the chemical compositions of the cheeses were di!erent depending on the amount of extract used, but no signi"cant
di!erences could be detected in the ripening index. With regard to electrophoretic pro"les, the two types of cheese could be
distinguished until up to ca. 7 d of ripening, but di!erences did essentially vanish by 28 d
Mechanical characterization of old chestnut beams
The main objective of this work is to evaluate, by non-destructive techniques, seven old Chestnut beams. For that, after the geometric assessment and the detailed visual inspection that allowed to strength grade the beams, a series of non-destructive tests was setup. In a first step, non-destructive bending tests, under the elastic limit, were performed to quantify the modulus of elasticity in bending (MoE) of the seven beams. Then, ResistographÂź and PilodynÂź tests were done to assess the superficial decay and to have aclearer idea of the voids dimensions. Then, two beams were tested in bending until failure to evaluate the bending strength. In a second step, end parts were cut from the beams, one per end of the beams, to perform ResistographÂź, PilodynÂź and ultrasound tests, to quantify the density of the beams and to extract meso-specimens to be used in tension parallel to the grain test
High dietary protein, n â 3/n â 6 ratio and ÎČ-carotene enhances Paracentrotus lividus (Lamarck, 1816) larval development
Fundação para a CiĂȘncia e Tecnologia (FCT), Grant/Award Number: LA/P/0069/2020, UIDB/04292/2020 and UIDP/04292/2020; Operational Programme MAR2020, Grant/Award Number: 16-02-01-FMP-0004; Scientific
Employment Stimulus Programmes, Grant/Award Number: CEECINST/00051/2018; European Regional Development Fund, Grant/Award Number: Centro-01-0145-FEDER-000018.The nutritional characteristics of microalgae affect the growth, survival and fatty acid composition of sea urchin larvae. This study aimed to evaluate the influence of nutritive characteristics of single microalgal diets in Paracentrotus lividus (Lamarck, 1816) larval development, growth, and condition. Larvae of P. lividus were fed with three monospecific microalgal diets, Rhodomonas sp. (Rho), Dunaliella tertiolecta (Duna) and the diatom Chaetoceros calcitrans (Chae), and their development and growth were analysed until competence. Additionally, the fatty acid (FA) profile of larvae was analysed at competence and compared with the FA profile of the correspondent diet. The three groups of larvae attained competence simultaneously with differences in growth performance. The larvae fed with Chae attained the largest stomach and the shortest post-oral arm. The larvae were able to accumulate long-chain polyunsaturated fatty acids (PUFA), such as docosahexaenoic (DHA, C22:6n â 3), eicosapentaenoic (EPA, C20:5n â 3) and arachidonic (ARA, C20:4n â 6) acids, either by assimilation and retention of dietary FA or by the synthesis from α-linolenic acid (ALA, C18:3n â 3) and
linoleic acid (LA, C18:2n â 6). Furthermore, the low DHA/EPA ratio and high EPA/ARA and n â 3/n â 6 ratios of Rho and Chae and the high levels of the ÎČ-carotene present in Chae improved larval growth and development. In conclusion, the results indicated that of the three microalgal diets tested, C. calcitrans provided important nutritional characteristics, especially in terms of FA composition and carotenoids, improving P. lividus larval growth and condition.info:eu-repo/semantics/publishedVersio
Comportamento a acçÔes perpendiculares ao plano, de alvenaria de enchimento com dano prévio
Com a entrada em fase de obrigatoriedade dos EurocĂłdigos surgem novos requisitos que tĂȘm de ser cumpridos pelos edifĂcios, ou pelas suas partes. Ă o caso da exigĂȘncia de garantia de estabilidade de painĂ©is de alvenaria nĂŁo estrutural, Ă acção sĂsmica perpendicular ao plano, em edifĂcios com sistema estrutural de betĂŁo armado.
Este documento apresenta a campanha de ensaios realizada na Universidade do Minho, com vista Ă caracterização do comportamento de elementos deste tipo a estas acçÔes, quando danificados previamente por acçÔes no plano. Para o efeito o esquema de ensaio proposto Ă© composto por duas fases. Na primeira o painel Ă© sujeito, de forma cĂclica e gradual, a um nĂvel de deslocamento de referĂȘncia no plano. Na segunda Ă© sujeito a uma acção cĂclica, uniforme e perpendicular ao plano. SerĂŁo testadas e comparadas quatro soluçÔes construtivas distintas, nomeadamente: parede simples nĂŁo reforçada, parede dupla nĂŁo reforçada, parede simples com reforço em junta horizontal e parede simples com reforço em malha de aço. De acordo com o desenvolvimento dos trabalhos, serĂŁo apresentados os resultados de uma parede simples
Invisible trophic links?:Quantifying the importance of non-standard food sources for key intertidal avian predators in the Eastern Atlantic
Coastal wetlands are heterogeneous systems with multiple inputs and complex interactionswithin local food webs. Interpreting such complexity is limited by incomplete knowledgeof trophic interactions among organisms. Although widely recognized as secondary consumersand predators of intertidal macroinvertebrates, shorebirds can also consume lower-trophic-levelfood sources, and frequently forage in adjacent supratidal habitats. To ascertain potential trophiclinks between overwintering shorebirds and alternative non-standard food sources, we collectedcarbon and nitrogen stable isotope data of shorebirds and benthic organisms from 4 coastal wetlandsalong the Eastern Atlantic: Tejo Estuary, Portugal; Sidi-Moussa, Morocco; Banc dâArguin,Mauritania; and BijagĂłs Archipelago, Guinea-Bissau. Using dual-isotope Bayesian mixing models,we evaluated the relative importance of intertidal benthic macroinvertebrates and 3 otherpotential food sources (biofilm and seagrass rhizomes from intertidal areas, and saltpan macroinvertebrates)in the diet of wintering shorebirds. Although intertidal macroinvertebrates form themain part of most shorebird speciesâ diet, our data revealed that supratidal saltpans can contributeto >30% of the biomass ingested by several shorebird species. Seagrass rhizomes represented>10% of the diet of several species in Banc dâArguin and in Sidi Moussa. Little stint Calidris minutaappears to consume biofilm on all 3 wetlands where they were sampled, which is the first timebiofilm consumption by shorebirds has been detected along the East Atlantic Flyway. Empiricalevidence for generalized consumption of alternative food sources by intertidal avian predatorsshow the greater complexity and food web connectivity in and of intertidal habitats, and also withthe surrounding habitats
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