27 resultados para Active population


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Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Eletrónica Médica)

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A high-resolution mtDNA phylogenetic tree allowed us to look backward in time to investigate purifying selection. Purifying selection was very strong in the last 2,500 years, continuously eliminating pathogenic mutations back until the end of the Younger Dryas (∼11,000 years ago), when a large population expansion likely relaxed selection pressure. This was preceded by a phase of stable selection until another relaxation occurred in the out-of-Africa migration. Demography and selection are closely related: expansions led to relaxation of selection and higher pathogenicity mutations significantly decreased the growth of descendants. The only detectible positive selection was the recurrence of highly pathogenic nonsynonymous mutations (m.3394T>C-m.3397A>G-m.3398T>C) at interior branches of the tree, preventing the formation of a dinucleotide STR (TATATA) in the MT-ND1 gene. At the most recent time scale in 124 mother-children transmissions, purifying selection was detectable through the loss of mtDNA variants with high predicted pathogenicity. A few haplogroup-defining sites were also heteroplasmic, agreeing with a significant propensity in 349 positions in the phylogenetic tree to revert back to the ancestral variant. This nonrandom mutation property explains the observation of heteroplasmic mutations at some haplogroup-defining sites in sequencing datasets, which may not indicate poor quality as has been claimed.

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A therapeutic deep eutectic system (THEDES) is here defined as a deep eutectic solvent (DES) having an active pharmaceutical ingredient (API) as one of the components. In this work, THEDESs are proposed as enhanced transporters and delivery vehicles for bioactive molecules. THEDESs based on choline chloride (ChCl) or menthol conjugated with three different APIs, namely acetylsalicylic acid (AA), benzoic acid (BA) and phenylacetic acid (PA), were synthesized and characterized for thermal behaviour, structural features, dissolution rate and antibacterial activity. Differential scanning calorimetry and polarized optical microscopy showed that ChCl:PA (1:1), ChCl:AA (1:1), menthol:AA (3:1), menthol:BA (3:1), menthol:PA (2:1) and menthol:PA (3:1) were liquid at room temperature. Dissolution studies in PBS led to increased dissolution rates for the APIs when in the form of THEDES, compared to the API alone. The increase in dissolution rate was particularly noticeable for menthol-based THEDES. Antibacterial activity was assessed using both Gram-positive and Gram-negative model organisms. The results show that all the THEDESs retain the antibacterial activity of the API. Overall, our results highlight the great potential of THEDES as dissolution enhancers in the development of novel and more effective drug delivery systems.

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Tese de Doutoramento em Biologia de Plantas

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Dissertação de mestrado integrado em Engenharia Civil

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Tese de Doutoramento em Biologia de Plantas MAP - Bioplant

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Strategic funding of UID/BIO/04469/2013 unit and project ref RECI/BBB-EBI/0179/2012 (project number FCOMP-01-0124-FEDER-027462) and Xanel Vecino post-doctoral grant (ref SFRH/BPD/101476/2014) funded by Fundação para a Ciência e a Tecnologia, Portugal

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Relatório de mestrado em Ensino de Educação Física nos Ensinos Básico e Secundário

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Dissertação de mestrado em Estatística

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[Excerpt] In this work, different multilayer structures, using a polyhydroxybutyrate-co-valerate film with a valerate content of 8% (PHBV8) as support, were developed aiming the development of active bio-based multilayer systems. An interlayer based on zein nanofibers with and without cinnamaldehyde were electrospun in the PHBV8 film and three multilayer systems were developed: 1) without an outer layer; 2) using a PHBV8 film as outer layer; and 3) using an alginate-based film as outer layer. Their physico-chemical properties were evaluated through: water vapour and oxygen permeabilities and colour measurements, Fourier Transform Infrared Spectroscopy (FTIR) and thermal analyses. Results showed that the presence of different outer layers affected the water vapour permeability and transparency of the multilayer films. (...)

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This paper presents a model predictive current control applied to a proposed single-phase five-level active rectifier (FLAR). This current control strategy uses the discrete-time nature of the active rectifier to define its state in each sampling interval. Although the switching frequency is not constant, this current control strategy allows to follow the reference with low total harmonic distortion (THDF). The implementation of the active rectifier that was used to obtain the experimental results is described in detail along the paper, presenting the circuit topology, the principle of operation, the power theory, and the current control strategy. The experimental results confirm the robustness and good performance (with low current THDF and controlled output voltage) of the proposed single-phase FLAR operating with model predictive current control.