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  • Cost/revenue performance in an IMT-Advanced scenario with Spectrum Aggregation over non-contiguous frequency bands
    Publication . Acevedo Flores, Jessica Elizabeth; Velez, Fernando J.; Cabral, Orlando; Robalo, Daniel Luís Silveira; Holland, Oliver; Aghvami, A. Hamid; Meucci, Filippo; Mihovska, Albena Dimitrova; Prasad, Neeli R.; Prasad, Ramjee
    This paper determines the cost/revenue performance of a mobile communication system in an IMT-Advanced scenario with integrated Common Radio Resource Management (iCRRM). The iCRRM performs classic CRRM functionalities jointly with Spectrum Aggregation (SA), being able to switch users between non-contiguous frequency bands. The SA scheduling is obtained with an optimized General Multi-Band Scheduling (GMBS) algorithm with the aim of cell throughput maximization. In particular, we investigate the dependence of the throughput on the cell coverage distance for the allocation of users over the 2 and 5 GHz bands for a single operator scenario under a constant average Signal to Interference-plus-Noise Ratio (SINR), for the same type of Radio Access Technology and both frequency bands. The operator has the availability of a non-shared 2 GHz band and has access to part (or all) of a shared frequency band at 5 GHz. An almost constant gain near 30 % was obtained with the proposed optimal solution compared to a system where users are first allocated in one of the two bands and later not able to handover between the bands. It is shown that the profit in percentage terms decreases as the cell radius increases. These results allow for evaluating the impact of the revenue from the channel in the total revenue and in the profit, defined as the difference between revenues and costs, in percentage. Maximum profits of about 1270, 585 and 240 % have been obtained for prices of 0.10, 0.05 and 0.025 €/MByte, respectively, when iCRRM is employed, while profits of 990, 440, and 170 % have been reached with no iCRRM, i.e., simple CRRM. Finally, an energy efficiency strategy is proposed and analyzed, showing that there is significant transmission power saving potential through the opportunistic reallocation scheme.
    2014-05Conference object Open access Show more
  • Pesquisa e identificação de compostos bioativos em plantas florestais
    Publication . Luís, Ângelo Filipe Santos; Domingues, Fernanda da Conceição
    A avaliação científica e experimental das propriedades das plantas, que os ancestrais utilizavam na medicina tradicional, conhece um grande desenvolvimento, nomeadamente na procura de novos compostos com propriedades antioxidantes e anti-microbianas. Os compostos com propriedades antioxidantes podem ser utilizados na medicina no tratamento de patologias, relacionadas com o stresse oxidativo, em alternativa à terapêutica habitual, ou pela indústria alimentar, na confeção de alimentos funcionais, ou como substitutos dos antioxidantes sintéticos. Os compostos anti-microbianos podem ser utilizados no tratamento de infeções por microrganismos resistentes aos antibióticos convencionais e na indústria alimentar na conservação dos alimentos. A área florestal portuguesa ascende aos 3,3 milhões de hectares, o que representa cerca de 38% do território, sendo uma importante fonte de matéria-prima com potencial atividade biológica. De entre o conjunto de constituintes ativos das plantas, os fenóis e os flavonoides têm sido estudados quanto às suas propriedades antioxidantes e de sequestração de radicais livres, assim como na inibição da peroxidação lipídica. As propriedades anti-microbianas destes compostos têm sido referidas, pois estes exercem nas plantas ação protetora contra microrganismos patogénicos. O objetivo geral deste trabalho foi melhorar o conhecimento sobre as atividades biológicas de extratos obtidos a partir de espécies vegetais existentes no ecossistema da Serra da Estrela (Echinospartum ibericum, Pterospartum tridentatum, Juniperus communis, Ruscus aculeatus, Rubus ulmifolius, Hakea sericea, Cytisus multiflorus, Crataegus monogyna, Erica arborea, Ipomoea acuminata e Ailanthus altissima), e de definir procedimentos para a sua extração e valorização como produtos naturais para uso terapêutico e/ou nutracêutico. Assim, com este trabalho pretendeu estudar-se as propriedades antioxidantes, anti-microbianas e citotóxicas de extratos das diversas partes aéreas (caules, folhas, flores e frutos) dos arbustos mencionados, e analisar o respetivo perfil fitoquímico, no que respeita a algumas classes de metabolitos secundários (fenóis, flavonoides, taninos e alcaloides). O método do reagente de Folin-Ciocalteu foi utilizado para a determinação do teor de fenóis totais e os taninos foram precipitados, a partir destes, com polivinilpolipirrolidona (PVPP); um método colorimétrico com cloreto de alumínio foi usado para a determinação dos flavonoides, e o método do reagente de Dragendorff foi utilizado para a estimativa dos alcaloides totais. O teste do 2,2-difenil-1-picril-hidrazil (DPPH) e o sistema β-caroteno/ácido linoleico foram utilizados para avaliar a atividade antioxidante dos extratos. A identificação dos compostos fenólicos presentes nos extratos foi efetuada por cromatografia líquida de alta eficiência de fase reversa (RP-HPLC). A atividade anti-microbiana dos extratos metanólicos de Hakea sericea foi avaliada pelo método da difusão em disco e pela determinação da Concentração Mínima Inibitória (MIC). A atividade anti-biofilme foi avaliada através da quantificação da biomassa total do biofilme utilizando o violeta de cristal, e pela avaliação da atividade metabólica do biofilme pelo método do 3′-{1-[(phenylamino)-carbonyl]-3,4-tetrazolium}-bis (4-methoxy-6-nitro)benzene-sulfonic acid hydrate (XTT) . A citotoxicidade foi avaliada por ensaios de hemólise e pelo teste do 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). A maioria dos extratos dos arbustos estudados apresentou um teor elevado de compostos fenólicos, bem como, propriedades antioxidantes significativas, que são provavelmente devidas à existência dos compostos fenólicos nos extratos, dado que se observou uma correlação linear positiva entre o Índice de Atividade Antioxidante (AAI) e teor de fenóis totais dos extratos. O procedimento de RP-HPLC mostrou que os compostos mais comuns eram os ácidos ferúlico e elágico e a quercetina. Destaca-se que para as espécies Echinospartum ibericum, Hakea sericea e Ipomoea acuminata, não existem estudos fitoquímicos anteriores e não se conhecem utilizações destas plantas na medicina tradicional. No geral, os extratos das folhas têm maior concentração de compostos fenólicos do que as outras partes aéreas dos arbustos. Resultados preliminares demonstraram as potenciais propriedades anti-microbianas da espécie Hakea sericea, que é um arbusto invasivo nas florestas Portuguesas. Neste trabalho foi avaliada a atividade anti-microbiana de extratos de Hakea sericea em várias espécies de microrganismos, incluindo a capacidade de inibição da formação de biofilmes. Adicionalmente foram avaliadas as propriedades citotóxicas destes extratos em células humanas. Para as bactérias Gram-positivas, os valores de MIC dos extratos metanólicos de Hakea sericea variaram entre 0.040 e 0.625mg/mL, enquanto para o extrato dos frutos se obtiveram os menores valores de MIC para várias espécies de microrganismos, nomeadamente, Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes e estirpes clínicas de Staphylococcus aureus resistentes à meticilina (MRSA). Os extratos dos caules e dos frutos (2.5mg/mL) erradicaram completamente os biofilmes das estirpes Staphylococcus aureus ATCC 25923, SA 01/10 e MRSA 12/08. Relativamente à toxicidade destes extratos, para as folhas, não foi observada hemólise, e no caso dos caules e dos frutos, apenas se verificou hemólise para concentrações muito elevadas, o que sugere a baixa toxicidade destes extratos. O extrato dos frutos não apresentou nenhum efeito tóxico para as células NHDF (Normal Human Dermal Fibroblasts), no entanto, para as concentrações de 0,017 e 0.008mg/mL, este extrato diminuiu a viabilidade da linha de células cancerígenas MCF-7 (human breast adenocarcinoma cells) em 60%, como os resultados do teste do MTT comprovaram. Após se ter verificado que o extrato metanólico bruto dos frutos de Hakea sericea apresentava significativa atividade biológica, procedeu-se ao seu fracionamento bioguiado, o que levou ao isolamento e identificação de um novo alquenilresorcinol, o ácido 9-(3,5-dihidroxi-4-metilfenil)nona-3-(Z)-enóico, composto aqui pela primeira vez descrito. A estrutura deste novo composto foi comprovada por espetroscopia de ressonância magnética nuclear (NMR), de infravermelho (FTIR) e por espetroscopia de massa de alta resolução (HRMS). As propriedades antibacterianas do novo alquenilresorcinol foram estudadas pela determinação dos seus valores de MIC contra várias bactérias Gram-positivas e Gram-negativas, utilizando o método da resazurina. O alquenilresorcinol isolado e identificado inibiu o crescimento das bactérias, Enterococcus faecalis, Listeria monocytogenes e Bacillus cereus, com valores de MIC de 0.31, 0.02 e 0.16mg/mL, respetivamente. Baixos valores de MIC foram também obtidos contra as estirpes de Staphylococcus aureus (0.005-0.16mg/mL), incluindo os isolados clínicos (SA 01/10 e SA 02/10) e as estirpes de MRSA. Dado que foram identificados nos extratos das plantas estudadas, vários compostos fenólicos, nomeadamente os ácidos gálico, cafeico e clorogénico, e como este grupo de compostos possui diversas atividades biológicas, foram neste trabalho analisadas as suas potenciais propriedades anti-microbianas e anti-biofilme em estirpes de Staphylococcus aureus, bem como o seu mecanismo de ação. Concluiu-se que estes ácidos fenólicos têm propriedades antiestafilocócicas, por exemplo, o ácido gálico influenciou as propriedades de adesão das células de Staphylococcus aureus. A produção de α-hemolisinas por estes microrganismos também foi inibida pelos ácidos gálico e cafeico. Em relação ao seu mecanismo de ação, o ácido cafeico interfere na estabilidade da membrana e com a atividade metabólica das células de Staphylococcus aureus. Em suma, este trabalho, contribuiu para o melhor conhecimento das propriedades biológicas de diversas espécies vegetais, valorizando algumas para as quais não é conhecida nenhuma aplicação na medicina tradicional, nomeadamente Echinospartum ibericum, Ailanthus altissima, Hakea sericea. Por outro lado, permitiu isolar de uma espécie invasora, um novo alquenilresorcinol com propriedades anti-microbianas, permitindo deste modo contribuir para a valorização da biomassa florestal e para a descoberta de um potencial novo antibiótico.
    2014-05Doctoral thesis Open access Show more
  • Evaluation of allergic rhinitis and asthma control in a Portuguese community pharmacy setting
    Publication . Lourenço, Olga; Calado, Sofia; Sá-Sousa, Ana; Fonseca, João
    BACKGROUND: Allergic rhinitis and asthma (ARA) are frequent respiratory diseases that often coexist, causing a high social and economic impact. It is important to maintain ARA disease control to reduce the disease burden. OBJECTIVE: To assess control in patients with 1 or both pathologies through the application of validated questionnaires at community pharmacies. METHODS: A cross-sectional study was conducted in the pharmacies of the Portuguese county of Covilhã (located in the central region of Portugal with about 53,000 inhabitants). Subjects aged between 18 and 70 years who presented a prescription for an asthma and/or allergic rhinitis medication were invited to participate in the study by responding to a questionnaire that included the Control of Allergic Rhinitis and Asthma Test (CARAT). The CARAT is a validated tool to simultaneously assess the control of ARA with scores that range from 0 to 30 points, 0 meaning the worst and 30 meaning the best possible control of disease. RESULTS: Of the 224 participants, 58% were female and the median age was 48.5 years. The median CARAT score was 19 (mean = 17.8 ± 5136.4), and 87% of participants had a score < 25, indicating noncontrolled disease. Female participants, the elderly, and those with less school education responded with scores that demonstrated significantly less disease control. CONCLUSIONS: Using a simple self-assessment questionnaire, such as the CARAT, pharmacists can help identify patients with uncontrolled ARA disease, which is an important first step to change patients’ knowledge about their disease, with an ultimate goal of improving ARA outcomes.
    2014-05Journal article Open access Show more
  • Performance assessment of real-time data management on wireless sensor networks
    Publication . Diallo, Ousmane; Rodrigues, Joel José Puga Coelho; Sene, Mbaye
    Technological advances in recent years have allowed the maturity of Wireless Sensor Networks (WSNs), which aim at performing environmental monitoring and data collection. This sort of network is composed of hundreds, thousands or probably even millions of tiny smart computers known as wireless sensor nodes, which may be battery powered, equipped with sensors, a radio transceiver, a Central Processing Unit (CPU) and some memory. However due to the small size and the requirements of low-cost nodes, these sensor node resources such as processing power, storage and especially energy are very limited. Once the sensors perform their measurements from the environment, the problem of data storing and querying arises. In fact, the sensors have restricted storage capacity and the on-going interaction between sensors and environment results huge amounts of data. Techniques for data storage and query in WSN can be based on either external storage or local storage. The external storage, called warehousing approach, is a centralized system on which the data gathered by the sensors are periodically sent to a central database server where user queries are processed. The local storage, in the other hand called distributed approach, exploits the capabilities of sensors calculation and the sensors act as local databases. The data is stored in a central database server and in the devices themselves, enabling one to query both. The WSNs are used in a wide variety of applications, which may perform certain operations on collected sensor data. However, for certain applications, such as real-time applications, the sensor data must closely reflect the current state of the targeted environment. However, the environment changes constantly and the data is collected in discreet moments of time. As such, the collected data has a temporal validity, and as time advances, it becomes less accurate, until it does not reflect the state of the environment any longer. Thus, these applications must query and analyze the data in a bounded time in order to make decisions and to react efficiently, such as industrial automation, aviation, sensors network, and so on. In this context, the design of efficient real-time data management solutions is necessary to deal with both time constraints and energy consumption. This thesis studies the real-time data management techniques for WSNs. It particularly it focuses on the study of the challenges in handling real-time data storage and query for WSNs and on the efficient real-time data management solutions for WSNs. First, the main specifications of real-time data management are identified and the available real-time data management solutions for WSNs in the literature are presented. Secondly, in order to provide an energy-efficient real-time data management solution, the techniques used to manage data and queries in WSNs based on the distributed paradigm are deeply studied. In fact, many research works argue that the distributed approach is the most energy-efficient way of managing data and queries in WSNs, instead of performing the warehousing. In addition, this approach can provide quasi real-time query processing because the most current data will be retrieved from the network. Thirdly, based on these two studies and considering the complexity of developing, testing, and debugging this kind of complex system, a model for a simulation framework of the real-time databases management on WSN that uses a distributed approach and its implementation are proposed. This will help to explore various solutions of real-time database techniques on WSNs before deployment for economizing money and time. Moreover, one may improve the proposed model by adding the simulation of protocols or place part of this simulator on another available simulator. For validating the model, a case study considering real-time constraints as well as energy constraints is discussed. Fourth, a new architecture that combines statistical modeling techniques with the distributed approach and a query processing algorithm to optimize the real-time user query processing are proposed. This combination allows performing a query processing algorithm based on admission control that uses the error tolerance and the probabilistic confidence interval as admission parameters. The experiments based on real world data sets as well as synthetic data sets demonstrate that the proposed solution optimizes the real-time query processing to save more energy while meeting low latency.
    2014-05Doctoral thesis Open access Show more
  • Mecanismos de controlo da manipulação de resultados das sociedades não financeiras portuguesas: auditoria financeira e governo das sociedades
    Publication . Pereira, Agostinho Aires; Alves, Maria do Céu Ferreira Gaspar
    A presente investigação tem como objetivo geral fornecer uma melhor compreensão dos atuais mecanismos de controlo sobre as práticas de manipulação de resultados, para as sociedades não financeiras cotadas na Euronext Lisbon no período 2005-2011, bem como averiguar os efeitos da qualidade da auditoria, conselho de administração e do órgão de fiscalização. Com a primeira etapa da investigação pretende-se averiguar se após a adoção obrigatória das IAS/IFRS as sociedades não financeiras manipulam os resultados contabilísticos, mensurados através dos accruals discricionários. A metodologia de investigação utilizada assenta no modelo econométrico de Dechow et al. (2003). Executada uma análise de regressão linear univariada, os resultados empíricos permitem concluir que as sociedades não financeiras no período 2005-2011 apresentam indícios de manipulação de resultados. Na segunda etapa da investigação analisa-se a relação entre a auditoria e as práticas de manipulação de resultados. A metodologia baseia-se também num modelo econométrico, de Butler et al. (2004) e Bartov et al. (2001) sendo o mesmo reformulado, de modo a integrar a qualidade da auditoria. Realizada uma análise de regressão logística univariada, os resultados empíricos permitem concluir pela existência de uma associação estatisticamente significativa entre os accruals discricionários e a opinião de auditoria. Concluímos que quanto maior for a independência e competência do auditor maior será a qualidade da auditoria. Na terceira etapa da investigação estuda-se a relação entre o governo da sociedade e as práticas de manipulação de resultados. Nesta etapa a metodologia tem por base um modelo econométrico, de Klein (2002) sendo o mesmo reformulado, passando a integrar a qualidade da administração e fiscalização da sociedade. Efetuada uma análise de regressão linear univariada, os resultados empíricos evidenciam a existência de uma associação estatisticamente significativa entre os accruals discricionários e as características do conselho de administração. Concluímos que quanto maior for a independência e competência dos diretores externos maior será a qualidade do conselho de administração. As duas últimas etapas permitem-nos concluir que a existência de auditores e diretores externos reduz as práticas de manipulação de resultados. Esta investigação apresenta três contributos: o primeiro ao evidenciar que após a adoção das IAS/IFRS num país da Europa Continental continua a existir manipulação de resultados. O segundo ao adicionar aos modelos identificados na revisão da literatura a componente da qualidade da auditoria, do conselho de administração e fiscalização da sociedade. O terceiro contributo refere-se à melhor compreensão para a comunidade académica dos efeitos dos mecanismos de controlo sobre a manipulação de resultados nas sociedades não financeiras portuguesas cotadas na Euronext.
    2014-05Doctoral thesis Open access Show more
  • Study of molecular and cellular pathogenicity mechanisms of Arcobacter species
    Publication . Ferreira, Susana Margarida Paraíso; Domingues, Fernanda da Conceição; Queiroz, João António de Sampaio Rodrigues; Oleastro, Mónica Alexandra de Sousa
    Arcobacter is a genus of Gram-negative, spiral-shaped bacteria in the Epsilonproteobacteria class. It was first proposed in 1991 and was included in the Campylobacteraceae family together with the genera Campylobacter and Sulfurospirillum. There are currently 18 species described, among which A. butzleri, A. cryaerophilus and A. skirrowii are known to be human and animal pathogens. Arcobacter genus shows an unusually wide range of habitats, having been isolated from food, water, food processing and handling facilities, diverse environmental, animal and human samples. In fact, consumption of Arcobacter-contaminated food or water is regarded as the most probable cause of infection by this bacterium. Therefore it is important to evaluate its distribution in food or food processing environment, together with the assessment of its genetic variability and other phenotypic and genotypic features associated with virulence potential, to be able to understand the persistence mechanism of Arcobacter in the food chain. Thus, this study intend to evaluate the presence, genetic diversity, and virulence characteristics (namely antibiotic resistance, biofilm-forming capacity and detection of putative virulence genes) of A. butzleri strains isolated from poultry and from the environment of a Portuguese slaughterhouse. A. butzleri isolates revealed a high genetic diversity, with all isolates showing to be susceptible to gentamicin, in contrast to 55.8% that were resistant to ciprofloxacin. The latter resistance was associated with the presence of a cytosine to thymine transition in the quinolone resistance determining region of the gyrA gene. Among selected isolates, 72.2 % presented biofilm-forming ability and in all strains putative virulence genes were detected. These results highlight the relevance of A. butzleri relevance as food-borne pathogen. Taking into account that Arcobacter is potentially transmitted through contaminated food and is resistant to common antimicrobials, it is important to develop alternative control strategies that could be both effective and safe for human consumption. Therefore, the antimicrobial properties of resveratrol against A. butzleri and A. cryaerophilus were studied. Resveratrol exhibited a bacteriostatic or bactericidal activity dependent on cellular growth phase and resveratrol concentration, leading to both DNA content and metabolic activity reduction on Arcobacter cells. Resveratrol also showed the ability to act as an efflux pump inhibitor, and to induce cellular damage. Thus, resveratrol showed anti-Arcobacter activity, with the results obtained suggesting that this compound inhibits this microorganism through different pathways, which together with resveratrol beneficial properties described for human health may encourage its use as a food preservative. Some of the species of Arcobacter genus have been associated with gastrointestinal disease in humans, however there were a lack of studies evaluating its prevalence in Portugal, with the same happening for non-Campylobacter jejuni/coli species. Therefore, the frequency of Arcobacter and Campylobacter species in faeces from patients with diarrhoea in Portugal was assessed using a molecular approach. Concerning, Arcobacter and Campylobacter prevalence and distribution, 298 diarrhoeal samples from Portuguese patients were analysed, 1.3% of the samples were positive for A. butzleri and 0.3 % for A. cryaerophilus. Campylobacter species were found in 31.9 % of diarrhoeic faeces samples, with C. jejuni and C. concisus being the most prevalent species of this genus (13.7 % and 8.0 %, respectively). In this cohort of samples, A. butzleri was the fourth most frequent species. These results evidence the importance of Arcobacter and Campylobacter species as aetiological agents of acute gastroenteritis among Portuguese patients, affecting particularly the paediatric age group. Although A. butzleri has been implicated in human diseases, much of its pathogenesis and virulence factors remain unclear. Thus, A. butzleri virulence potential was also investigated, through the characterization of genotypic and pathogenic properties of human and non- human isolates. The isolates showed to be susceptible to tetracyclines and aminoglycosides, however displaying high resistance to quinolones. A. butzleri demonstrated a weak haemolytic activity and the ability to form biofilms in polystyrene surfaces. Adhesion levels similar to Salmonella Typhimurium were found for A. butzleri on Caco-2 cells, with pre- existing inflammation showing no significant effect on its adherence ability, yet invasion ability showed to vary among the isolates. A. butzleri was able of intracellular survival in Caco-2 cells and to induce a significant up-regulation of interleukin-8 secretion, as well as to promote structural cell disturbance. These data brings new insights to A. butzleri virulence and highlights its pathogenic potential. Overall in this work, the prevalence of Arcobacter species both in human and food-related samples was evaluated, contributing to understanding the epidemiology of Arcobacter in Portugal. The survival and persistence of this organism in the environment was highlighted due to its ability to form biofilms. Its relevance as a human pathogen was underlined by the resistance to antimicrobials, the presence of several putative virulence genes, along with its adherence, invasion, intracellular survival abilities and induction of proinflammatory cytokine secretion in intestinal epithelial cells. Finally, resveratrol was tested as an alternative to control the growth of Arcobacter. This work provided new insights on the epidemiology and pathogenicity of Arcobacter, and also identified a natural compound with anti-Arcobacter activity, which may contribute for future developments of new control approaches.
    2014-05Doctoral thesis Open access Show more
  • Experimental Characterization of Wearable Antennas and Circuits for RF Energy Harvesting in WBANs
    Publication . Saraiva, Henrique Morais; Borges, Luís M.; Pinho, Pedro; Gonçalves, Ricardo; Chavez-Santiago, Raul; Barroca, Norberto; Tavares, Jorge; Gouveia, Paulo T.; Carvalho, Nuno Borges; Balasingham, Ilangko; Velez, Fernando J.; Loss, Caroline; Salvado, Rita
    Field trials have been performed in Covilhã to identify the spectrum opportunities for radio frequency (RF) energy harvesting through power density measurements from 350 MHz to 3 GHz. Based on the identification of the most promising opportunities, a dual-band printed antenna was conceived, operating at GSM bands (900/1800), with gains of 1.8 and 2.06 dBi, and efficiency varying from 77.6 to 82%, for the highest and lowest operating frequency bands, respectively. In this paper, guidelines for the design of RF energy harvesting circuits and choice of textile materials for a wearable antenna are briefly discussed. Besides, we address the development and experimental characterization of three different prototypes of a five-stage Dickson voltage multiplier (with and without impedance matching circuit) responsible for RF energy harvesting. All the three prototypes (1, 2 and 3) can power supply the sensor node for RF received powers of 2 dBm, -3 dBm and -4 dBm, and conversion efficiencies of 6, 18 and 20%, respectively.
    2014-05Conference object Open access Show more
  • Thermoresponsive chitosan–agarose hydrogel for skin regeneration
    Publication . Miguel, Sónia P.; Ribeiro, MP.; Brancal, Hugo Gonçalo Monteiro Silva Aguiar; Coutinho, Paula Isabel Teixeira Gonçalves; Correia, Ilídio Joaquim Sobreira
    Healing enhancement and pain control are critical issues on wound management. So far, different wound dressings have been developed. Among them, hydrogels are the most applied. Herein, a thermoresponsive hydrogel was produced using chitosan (deacetylation degree 95%) and agarose. Hydrogel bactericidal activity, biocompatibility, morphology, porosity and wettability were characterized by confocal microscopy, MTS assay and SEM. The performance of the hydrogel in the wound healing process was evaluated through in vivo assays, during 21 days. The attained results revealed that hydrogel has a pore size (90–400 μm) compatible with cellular internalization and proliferation. A bactericidal activity was observed for hydrogels containing more than 188 μg/mL of chitosan. The improved healing and the lack of a reactive or a granulomatous inflammatory reaction in skin lesions treated with hydrogel demonstrate its suitability to be used in a near future as a wound dressing.
    2014-05-02Journal article Restricted access Show more
  • Stable weakly shadowable volume-preserving systems are volume-hyperbolic
    Publication . Bessa, Mário; Lee, Manseob; Vaz, Sandra
    We prove that any C1-stable weakly shadowable volume-preserving diffeomorphism defined on a compact manifold displays a dominated splitting E ⊕ F. Moreover, both E and F are volume-hyperbolic. Finally, we prove the version of this result for divergence-free vector fields. As a consequence, in low dimensions, we obtain global hyperbolicity.
    2014-05-15Journal article Open access Show more
  • Do desejo à invocação. Reptos da Adoção à Maternidade e à Paternidade
    Publication . Rosa, José Maria Silva
    Reflete-se sobre as razões do desejo de adotar, o superior interesse da criança no processo e a necessidade de maior discussão do assunto no quadro da «parentalidade plural» das nossas sociedades contemporâneas.
    2014-05-15Book part Open access Show more