1,367 research outputs found
First record of the Sculptured Mitten Lobster Parribacus antarcticus (Crustacea, Decapoda, Scyllaridae) from the Cabo Verde Islands (eastern Atlantic)
The lobster genus Parribacuscontains six living and one fossil species (Holthuis 1991; Chan 2010; Nyborg & Garassino 2017). In the Atlantic Ocean, only one living species is known, Parribacus antarcticus(Lund, 1793); it has been recorded in the western Atlantic from Florida to Brazil and recently also from the mid-Atlantic island of Ascension (Brown et al.2016). It is nocturnal and is often found hiding in crevices during daytime (Holthuis 1991). We here note the presence of Parribacus antarcticusat the Cabo Verde Islands, the first record of the species from the eastern Atlantic.info:eu-repo/semantics/publishedVersio
Seasonal photosynthesis, respiration, and calcification of a temperate Maërl bed in southern Portugal
Rhodolith (maerl) beds are biodiversity hotspots with a worldwide distribution. Maerl is the general term for free-living non-geniculate rhodoliths or coralline red algae. In southern Portugal, maerl beds are mainly composed of Phymatolithon lusitanicum, recently identified as a new species and commonly misidentified as Phymatolithon calcareum. Photosynthesis, respiration, and growth rates of the algae were measured seasonally, as well as the photosynthetic pigment composition. To characterize the seasonal and interannual patterns of key abiotic conditions in the largest described maerl bed of the Portuguese coast, temperature, irradiance, and dissolved oxygen were continuously monitored over a 2-year period. At the bed depth (22 m), temperature ranged between 14 degrees C in winter and 24 degrees C in summer, irradiance varied from 5 to 75 mu.mol m(-2) s(-1) , and dissolved oxygen from 5.8 to 7.25 mg O-2 L-1. We found a strong linear relationship (r(2) = 0.95) between gross primary production (GPP) and relative electron transport rates (rETRs). Both methods led to similar results and an average molar ratio of 0.24. Photosynthesis and respiration increased in summer and decreased in autumn and winter. In the summer of 2013, the growth rates were twofold higher (1.34 mu.mol CaCO3 g(-1) day(-1)) than in the other seasons. In winter and spring, to compensate for light deprivation and low temperature, algae increased their chlorophyll a and carotenoid concentrations while also decreasing their phycobilin concentration, in this case probably due to nutrient limitation. To isolate the role of temperature on the algae's metabolism, the photosynthetic and respiration rates of individual thalli were measured at eight different temperatures in the laboratory (from 12 degrees C to 26 degrees C). Phymatolithon lusitanicum photosynthesis increased twofold after a threshold of 18 degrees C (from 2.2 at 18 degrees C to 3.87 mu mol O-2 m(-2) s(-1) at 20 degrees C), whereas respiration increased fourfold with temperature after a threshold of 22 degrees C (from -0.38 at 18 degrees C to -1.81 (mu mol O-2 m(-2) s(-1) at 24 degrees C). The significant increases on respiration, photosynthetic rates, and maximum growth with temperature reveal that the metabolic rates of P. lusitanicum are highly sensitive to ocean warming.UIDB/04326/2020info:eu-repo/semantics/publishedVersio
Bond behaviour of NSM FRP systems in concrete
Doctorate Thesis in Civil EngineeringIn the context of strengthening concrete structures, the Near-Surface Mounted (NSM)
technique using Fibre Reinforced Polymers (FRP) has been shown as a sound solution.
This technique consists on inserting the FRP into grooves opened on the concrete elements
to be strengthened. Epoxy adhesives are the most commonly used binders. The
crucial aspect regarding the NSM FRP technique is related with the way the stresses are
transferred from the existing concrete to the added FRP, i.e. the bond behaviour. This
thesis principal objective was to add a contribution to the existing knowledge on the bond
behaviour of NSM FRP systems in concrete.
Considering that the bond behaviour is studied through bond tests, those were the
basis of the entire research presented in this document. Hence, a bibliographic survey was
conducted in order to obtain a database with the majority of the existing experimental
works on bond tests. Whenever available there were also collected the analytical bond
laws and the numerical strategies adopted by the authors to simulate their tests. With all
this information, three different tasks were defined, each addressing one important and
complementary aspect regarding the bond behaviour of NSM FRP systems in concrete:
an analytical, an experimental and a numerical task.
The analytical task was composed by the following three steps: (i) assess the accuracy
of the existing bond laws, calibrate them and/or propose improvements; (ii) introduce data
mining algorithms as alternative bond laws; (iii) calibrate the necessary safety factors in
order to allow using the bond laws in the design of NSM FRP systems in concrete.
In the experimental task, a campaign of direct pullout tests was defined in order to
allow, in the near future, the establishment of a standard direct pullout test. In addition,
parameters which were not yet used for studying the bond behaviour were included in this experimental campaign.
Finally, the numerical task consisted on the development of an interface constitutive
model based on the plasticity theory to allow 3D numerical simulations of NSM FRP
systems. This constitutive model was implemented in FEMIX software and validated
using pullout test’s results.No âmbito do reforço de estruturas de betão, a técnica de NSM com recurso a polÃmeros
reforçados com fibras (FRP) tem-se revelado uma boa solução. Esta técnica consiste em
inserir FRP em entalhes abertos nos elementos de betão a reforçar. Adesivos epóxi são
os ligantes mais frequentemente utilizados. O aspeto crucial da técnica NSM FRP está
relacionado com a forma como as tensões são transferidas do betão existente para o FRP
adicionado, i.e., o comportamento da ligação. O principal objetivo desta tese foi contribuir
para o conhecimento sobre o comportamento da ligação em sistemas NSM FRP no betão.
Considerando que o comportamento da ligação é estudado através de ensaios de arranque,
estes foram a base de toda a pesquisa apresentada neste documento. Assim, foi
realizada uma pesquisa bibliográfica de modo a obter uma base de dados com a maioria
dos trabalhos experimentais existentes sobre ensaios de arranque. Sempre que existissem,
também foram coletadas as leis analÃticas de aderência e as estratégicas numéricas adotadas
pelos autores para simular os seus ensaios. Com toda esta informação, três tarefas
diferentes foram definidas, cada uma abordando um aspeto importante e complementar
sobre o comportamento da ligação de sistemas NSM FRP no betão: uma tarefa analÃtica,
uma experimental e uma numérica.
A tarefa analÃtica era composta pelas seguintes três etapas: (i) avaliar a precisão das
leis de aderência existentes, calibrá-las e/ou propor melhorias; (ii) introduzir os algoritmos
de data mining como leis de aderência alternativas; (iii) calibrar os fatores de segurança
necessários de modo a permitir o uso das leis de aderência no dimensionamento de sistemas
NSM FRP no betão.
Na tarefa experimental, foi definida uma campanha de ensaios de arranque de modo
a permitir, num futuro próximo, o estabelecimento de um ensaio de arranque direto standard. Adicionalmente, foram adicionados nesta campanha experimental parâmetros
que ainda não foram utilizados no estudo do comportamento da ligação.
Finalmente, a tarefa numérica consistiu no desenvolvimento de uma lei constitutiva
de interface baseada na teoria da plasticidade para permitir simulações numéricas 3D de
sistemas NSM FRP. Esta lei constitutiva foi implementada no software FEMIX e validada
usando resultados de ensaios de arranque
Process characterization for dynamic design space development: An intensified design of experiment method
In this contribution, an intensified Design of Experiment (iDoE) methodology will be introduced. The iDoE approach is based on the idea that the values of certain factors do not need to be kept constant throughout the experiments. Instead the value of the factors can be changed during the experiments, e.g. after a specified time a step-change from 23 to 30 (°C) can be applied in temperature. In this way a classical Design of Experiment plan can in principle be executed using less experiments.
The iDoE method is applied to industrial and simulated E.coli fed-batch fermentations. A dynamic hybrid modeling method is adopted for the analysis of the data, since the analysis cannot be accomplished with the traditional static statistical methods. The process understanding gathered from the iDoE is compared to DoE results. The results suggest that the number of experiments can be reduced by factor of three to two, meaning less than half of the experiments of a classical DoE are required with the iDoE method. In addition, the understanding of the process dynamics is much improved, which is of particular importance to assess the impact of temporal deviations in the factors on the process response
Caracterização magnética de nanopartÃculas em matrizes amorfas
Tese de mestrado, Engenharia FÃsica, Universidade de Lisboa, Faculdade de Ciências, 2010O principal objectivo desta tese foi fazer um estudo do comportamento magnético de nanopartÃculas magnéticas inseridas em sistemas diamagnéticos amorfos. Neste trabalho estudaram-se dois sistemas: nanopartÃculas de ouro (Au) dispersas em celulose e nanopartÃculas de óxido de nÃquel (NiO) dispersas em vidro. No primeiro caso, as nanopartÃculas de ouro foram diluÃdas em celulose com diferentes concentrações pretendendo-se analisar o comportamento magnético das amostras em função da concentração de nanopartÃculas e do estiramento da celulose. A dimensão média das nanopartÃculas de ouro utilizadas é aproximadamente 2.85nm, dimensão a que é esperado comportamento magnético (a dimensão das partÃculas foi estimada a partir de resultados de microscopia electrónica de transmissão (TEM)). No segundo caso, as nanopartÃculas de óxido de nÃquel (NiO) foram crescidas em vidro de sÃlica nanoporoso. O óxido de nÃquel é antiferromagnético mas na forma de nanopartÃculas, o efeito de superfÃcie implica não compensação dos momentos magnéticos e torna as partÃculas magnéticas. Neste caso, estudaram-se 3 distribuições de tamanhos médios diferentes, caracterizadas por TEM, que permitiram fazer um estudo do comportamento magnético em função da dimensão e a sua evolução após tratamento térmico. Em todas as situações e para todas as amostras, de ouro e de óxido de nÃquel, foram realizadas medidas de magnetização a diferentes temperaturas e para diferentes valores de campo magnético. Nesta dissertação faz-se inicialmente uma introdução aos diferentes comportamentos magnéticos dos materiais e descrevem-se as técnicas experimentais utilizadas para obtenção dos resultados. Em seguida apresentam-se e discutem-se separadamente os resultados experimentais obtidos para cada um dos sistemas referidos e as principais conclusões a que conduziram.The main purpose of this thesis is to study the magnetic behaviour of nanoparticles inserted into diamagnetic amorphous matrix. Two systems were studied in this work: gold nanoparticles (Au) diluted in celulose and nickel oxide particles inserted in glass. In the first case the particles were diluted in cellulose with different concentrations. The gold nanoparticles average dimensions were around 2.85nm (estimated through transmission electronic microscopy (TEM)) and expected to be magnetic. Several samples have been prepared with different concentrations, to study the magnetic behaviour as a function of concentration and cellulose influence. In the second case, Nickel Oxide (NiO) nanoparticles were grown inside nanoporous Vycor glass. Bulk nickel oxide is antiferromagnetic, but when structured as nanoparticles the surface anisotropy induces a magnetic moment on the particles. In this case, 3 distributions of different average particle sizes were studied. Their magnetic behaviour was related to the dimension of the particles. and its evolution after thermal treatment was studied. Measurements of magnetization at different temperatures and for different applied magnetic field were carried out for all the samples of gold and nickel oxide. In this text, after the introduction, an overview of the magnetic behaviour of materials is presented in chapter 2, and the description of the experimental techniques used is carried out in chapter 3. In the chapters 4 and 5, the experimental results obtained for each of the systems are presented and discussed
The logistic giant emerge amid the pandemic: the value creation of fedex corporation
This dissertation aims to provide an independent view of the future of FedEx Corporation. Despite the recent sell-off after ground margins fell short of investors' expectations, FedEx is benefiting from interesting trends across all the business segments. Those trends include the shift towards online shopping accelerated by the pandemic, a recovery in the economy around the world and the constraint of passenger capacity. Therefore, this report points towards a buy recommendation with a target price of $286.50 as of December 31st, 2021, translating into an11.4% total shareholder return over the next 12-months
Projecto de educação alimentar: avaliação da intervenção em crianças do 1.º ciclo
[resumo][abstract
The role of national institutions and product architecture in joint decision-making in supply chains
info:eu-repo/semantics/publishedVersio
Surface behavior of pelagic juvenile loggerhead sea turtles in the eastern North Atlantic
Sea turtles bask at the ocean surface, but little is known about the patterns and ecological context of surface
behavior in the wild. This study investigated the surface behavior of ten juvenile loggerhead sea turtles (34 - 58
cm straight carapace length) satellite tagged in Madeira, in the pelagic eastern North Atlantic. During a total of
2273 tracking days, turtles moved through oceanic areas with a mean depth of ~3400 m. On average, turtles
spent one third of the time at the surface (0 - 1 m depth), spending 43% of the time at the surface during the day
and 29% of the time during the night. Generalized linear mixed modelling showed that the proportion of time at
the surface was significantly larger during the day, particularly during spring and summer. Time spent at the
surface during the day increased with elevated air temperatures and weak winds, probably to maximize the
benefits of solar absorption. Conversely, the probability of being at the surface during the day decreased as
horizontal search effort increased, suggesting a trade-off between basking and daytime foraging activities. At
night, time spent at the surface was not associated with air temperature or wind speed but was instead positively
associated with moon illumination. As turtles tend to dive deeper during clear nights, increased surface time may
be needed to recover from deeper dives. This study presents important aspects of the behavioral ecology of the
species during the oceanic juvenile phase. The findings reported here may be relevant for species management
and conservation, including correction of census data and management of interactions with surface fishing gear
and other anthropogenic activities.info:eu-repo/semantics/publishedVersio
Indoor Sound Based Localization: Research Questions and First Results
Part 17: TelecommunicationsInternational audienceThis PhD work has the goal to develop an inexpensive, easily deployable and widely compatible localization system for indoor use, suitable for pre-installed public address sound systems, avoiding costly installations or significant architectural changes in spaces. Using the audible sound range will allow the use of low cost off-the-shelf equipment suitable for keeping a low deployment cost. The state-of-the-art presented in this paper evidences a technological void in low-cost, reliable and precise localization systems and technologies. This necessity was also confirmed by the authors in a previous project (NAVMETRO®) where no suitable technological solution was found to exist to overcome the need to automatically localize people in a public space in a reliable and precise way.Although research work is in its first steps, it already provides a thorough view on the problem while discussing some possible approaches and predicting strategies to overcome the key difficulties. Some experiments were already conducted validating some initial premises and demonstrating how to measure the signal’s time-of-flight necessary to infer on distance calculations
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