Browsing by Issue Date, starting with "2014-04"
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- Energy Harvesting Methods for Medical DevicesPublication . Gaspar, Pedro Dinis; Felizardo, Virginie; Garcia, Nuno M.The evolution of medical equipments and health care involve the miniaturization of devices related to that area. The biggest challenge to this goal is the reduction of battery and/or a search for alternative energy sources. In this chapter, we discuss some sources for energy harvesting, its main methods of conversion, and several applications developed for medical equipments. In order to provide some future prospects, the current state of technology and future trends are addressed, accessing some possible approaches in the development of medical equipments.
- Mesomorfologia da acção em Aristóteles: os limites da decisão no limiar da phronesisPublication . Amaral, José António Campelo de Sousa; Martins, António Manuel; Santos, José Manuel Boavida dosO que significa decidir? Melhor dito: o que significa tomar ou fazer uma decisão no acto consciente de a decidir tomar ou fazer? Pesando os “prós” e os “contras” para encontrar o balanceamento certo de uma escolha? Mantendo a “cabeça fria” para avaliar os riscos inerentes à possibilidade de sucesso ou fracasso de uma opção? Neutralizando a torrente impulsiva das paixões e das emoções para melhor escutar a voz da consciência, seguir os ditames da razão, ou decifrar a codificação electroquímica da estrutura neuronal, consoante a perspectiva adoptada? E se a configuração ética do acto decisionário não sendo apenas isso, mas, pressupondo e incluindo isso, for mais do que isso, a saber uma experiência discursiva da acção na sua irrecusável epifania?
- Effect of amniotic membrane proteins in human cancer cell lines: an exploratory studyPublication . Mamede, Ana Catarina Manjolinha; Laranjo, Marta; Carvalho, Maria J; Abrantes, Ana M; Pires, A S; Brito, A F; Moura, P; Maia, C J; Botelho, M FHuman amniotic membrane (hAM) has recently drawn attention as an upcoming anti-cancer therapy. Regarding the strategies which have already investigated, little is known about hAM protein extracts (hAMPE) effect on cancer. So, this work aims to study the effect of hAMPE in metabolic activity of several human cancer cell lines. hAMPE were mechanically obtained, thus avoiding the effect of detergents and other reagents commonly used in protein extraction under the cell lines studied. After quantification of proteins in hAMPE, their effect on the metabolic activity of 21 human cancer cell lines was assessed by 3-(4,5-dimethylthia-zolyl-2)2,5-diphenyltetrazolium bromide (MTT) assay. Our results indicate that there is an inhibition of metabolic activity until 25 and 50% in two and seven cell lines, respectively. Five cell lines proved to be very sensitive to hAMPE, being its metabolic activity more than 50% inhibited. Our results show that hAMPE can inhibit the metabolic activity of some human cancer cell lines. However, research about this cell line-dependent response to hAMPE becomes indispensable.
- A two-phase contention window control scheme for decentralized wireless networksPublication . Borges, Luís M.; Velez, Fernando J.; Oliveira, RodolfoMost studies on performance of IEEE 802.11 distributed coordination function (DCF) have proved that the binary exponential backoff (BEB) algorithm suffers from low throughput, long transmission delays and low transmission reliability, for a high traffic load. In this paper, we propose a two-phase contention window (TPCW) access mechanism that enhances the aggregate throughput and transmission reliability while decreasing the medium access delay. In addition, this scheme aims at being computationally simple. This work characterizes the performance of the TPCW mechanism for different parameterization values. An analytical model is proposed for the TPCW access mechanism, which characterizes the frame transmission reliability, the total transmission delay and the aggregate throughput. The validity of our analytical model is verified through extensive simulations. By comparing the performance results, we conclude that the proposed scheme can significantly enhance IEEE 802.11 in terms of frame transmission reliability, total transmission delay and aggregate throughput.
- Inflation in a two 3-form fields scenarioPublication . Kumar, K. Sravan; Marto, João; Nunes, Nelson J.; Moniz, PauloA setting constituted by N 3-form fields, without any direct interaction between them, minimally coupled to gravity, is introduced in this paper as a framework to study the early evolution of the universe. We focus particularly on the two 3-forms case. An inflationary scenario is found, emerging from the coupling to gravity. More concretely, the fields coupled in this manner exhibit a complex interaction, mediated by the time derivative of the Hubble parameter. Our investigation is supported by means of a suitable choice of potentials, employing numerical methods and analytical approximations. In more detail, the oscillations on the small field limit become correlated, and one field is intertwined with the other. In this type of solution, a varying sound speed is present, together with the generation of isocurvature perturbations. The mentioned features allow to consider an interesting model, to test against observation. It is subsequently shown how our results are consistent with current CMB data (viz.Planck and BICEP2).
- Improved Minicircle DNA Biosynthesis for Gene Therapy ApplicationsPublication . Gaspar, V. M.; Maia, C J; Queiroz, João; Pichon, Chantal; Correia, Ilídio; Sousa, FaniMinicircular DNA (mcDNA) biopharmaceuticals have recently risen as a valuable alternative for the development of a next generation of bioactive therapeutics because they are more efficient and safer than standard plasmid DNA (pDNA). To date, the relatively insufficient knowledge regarding mcDNA biosynthesis is currently hindering its manufacture in suitable amounts for clinical trial evaluations. Addressing this limitation is therefore mandatory to bring forth the full therapeutic potential of this cutting-edge technology. Herein, we describe for the first time new processing parameters that improve the overall yield of mcDNA obtained from bacterial fermentations. We provide details for further in-line monitoring and optimization in view of the current good manufacturing guidelines. Our results show that by rising growth temperature to 42°C, an increase in the overall minicircle producer plasmid yield is attained, while biomass amounts are reduced. Moreover, by monitoring in real time the dynamic recombination of parental plasmids to mcDNA, we found that this event is more efficient at specific time points, regardless of the growth temperature and inductor concentration used. These are important findings since mcDNA can be recovered with higher yields at these determined key stages. Indeed, the manipulation of these parameters resulted in a 2.21-fold increase in mcDNA production compared with the established growth temperatures for this technology. Overall, our findings highlight that to achieve maximum productivity while attaining pharmaceutical-grade mcDNA preparations, process design and biosynthesis optimization must take into account key parameters such as temperature, inductor concentration, and recovery time.
- Stakeholder engagement and the diffusion of childbirth knowledge: experiences of the COST project.Publication . Schouten, Maria Johanna Christina; White, Joanna; Berg, Marie; Magistretti, Claudia MeierPoster presenting the diverse actions in various European countries, participating in the project COST IS0907, to promote improvement in childbirth procedures and conditions. Seminars were organized between 2011 and 2013 as an offshoot of COST Action IS0907, “Childbirth Cultures, Concerns and Consequences: Creating a Dynamic EU Framework for optimal maternity care”. The aim of these events was to engage various stakeholders in exchanging research and experiences related to the improvement of maternity practice in each country setting. Different approaches were pursued. This installation aims to share what took place at the seminars.
- Natural melanin: A potential pH-responsive drug release devicePublication . Araújo, Marco; Viveiros, Raquel; Correia, Tiago R.; Correia, Ilídio Joaquim Sobreira; Bonifácio, Vasco; Casimiro, Teresa; Ricardo, Ana AguiarThis work proposes melanin as a new nanocarrier for pH-responsive drug release. Melanin is an abundant natural polymer that can be easily extracted from cuttlefish as nanoparticles with a suitable size range for drug delivery. However, despite its high potentiality, the application of this biopolymer in the pharmaceutical and biomedical fields is yet to be explored. Herein, melanin nanoparticles were impregnated with metronidazole, chosen as model antibiotic drug, using supercritical carbon dioxide. The drug release profile was investigated at acidic and physiologic pH, and the dominant mechanism was found to follow a non-Fickian transport. Drug release from melanin shows a strong pH dependency, which allied to its biocompatibility and lack of cytotoxicity envisages its potential application as nanocarrier in formulations for colon and intestine targeted drug delivery.
- Stable weak shadowable symplectomorphisms are partially hyperbolicPublication . Bessa, Mario; Vaz, SandraLet M be a closed, symplectic connected Riemannian manifold and f a symplectomorphism on M. We prove that if f is C1-stably weak shadowable on M, then the whole manifold M admits a partially hyperbolic splitting.