Browsing by Issue Date, starting with "2011-03"
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- Apresentação do R com um exemplo de análise de regressão não-linearPublication . Esteves, EduardoNo seguimento dum artigo anterior acerca da análise de regressão não-linear (simples) utilizando a ferramenta Solver®do Excel® (Esteves, 2010) propõe-se neste artigo a apresentação do R, uma linguagem de programação e um ambiente para computação estatística e gráfica, através da sua aplicação na "descrição" de relações estatísticas (não-lineares) entre variáveis.
- Long-term effects of fishing on physiological performance of the Manila clam (Ruditapes philippinarum) in the Lagoon of VenicePublication . Moschino, Vanessa; Chicharo, Luis; Marin, Maria GabriellaThe Manila clam (Ruditapes philippinarum) is an important economic resource for fisheries in the Lagoon of Venice, where this species is fished and farmed. With the aim of evaluating possible fishing-induced long-term effects undergone by clam populations subjected to fishing efforts, physiological biomarkers were measured at organism level (clearance and respiration rates, scope for growth and survival-in-air test). Clams were collected on a seasonal basis from sites characterized by various fishing management practices: a free fishing area at S. Angelo and an area licensed for clam farming at Chioggia, where a non-fishing sub-area was established. R. philippinarum collected at S. Angelo generally showed reduced filtering activity and higher oxygen consumption, revealing general worsening in clam well-being in comparison with individuals from both Chioggia areas. This condition, resulting in lower standardized scope for growth values, may be explained by both environmental and fishing effort differences. Comparing Chioggia samples, better physiological performances were exhibited by clams from the non-fishing area, though no significant differences were observed. In winter, the survival-in-air test revealed the detrimental effects of fishing on clams, whereas in the other seasons this response generally seemed to be mostly related to other exogenous and endogenous factors. Although differences among sites and seasons were always statistically significant, all physiological parameters indicate the great tolerance of R. philippinarum to changing environmental conditions.
- On a 3D-hypersingular equation of a problem for a crackPublication . Samko, StefanWe show that a certain axisymmetric hypersingular integral equation arising in problems of cracks in the elasticity theory may be explicitly solved in the case where the crack occupies a plane circle. We give three different forms of the resolving formula. Two of them involve regular kernels, while the third one involves a singular kernel, but requires less regularity assumptions on the the right-hand side of the equation.
- Development of a highly sensitive bacteria detection assay using fluorescent pH-responsive polymeric micellesPublication . Mouffouk, Fouzi; Rosa da Costa, Ana; Martins, Jorge; Zourob, Mohammed; Abu-Salah, Khalid; Alrokayan, Salman A.The detection and control of bacteria is extremely important in the safety of food products and health systems. The conventional microbiological methods based on culture enrichment techniques and plating procedures are highly sensitive and selective for bacterial detection but are expensive, cumbersome and time-consuming. Here we report the development of a simple and sensitive bioassay to detect Escherichia coli (E. coli) bacteria by using self assembled pH-responsive polymeric micelles that have been bioconjugated to anti-E. coli (capturing agent). Poly(ethylene glycol-b-trimethylsilyl methacrylate), containing silicon moieties that can be cleaved under mildly acidic conditions, was synthesized and selfassembled into micelles, that were loaded with a fluorescent dye (1-methylpyrene). The polymer silicon protecting groups are used as a tool to remotely activate the dye release by means of pH. The high sensitivity of the newly developed bioassay, which is capable of detecting 15 bacteria per milliliter of solution, is due to an amplification effect generated by the optical signal of millions of fluorophores released from a single micelle upon attachment to a bacterium. Fluorescence probing involves the measurements of changes in the emission spectra, through the disappearance of the excimer band, which only occurs when the dye molecules are trapped within the polymeric micelles.
- Design of a UAN node capable of high-data rate transmission dual-link multinode underwater commuinication access point allows transmission of large amounts of data to shorePublication . Zabel, F.; Martins, C.; Silva, A.In recent years, underwater acoustic networks have become one of the most challenging topics in ocean acoustics.
- Effect of informed consent for administration of intravenous contrast material in the anxiety level of patients submitted to computed tomography examsPublication . Azevedo, Kevin; Abrantes, António; Ribeiro, Luís; Almeida, Rui; Silva, CarlosPurpose: Evaluation and relation of the state and trait anxiety level in patients before the delivery of informed consent with patients after that, and the evaluation of eventual relations between psychometric tests and sociodemographic characteristics. Methods and Materials: The present study is quasi-experimental. The total sample of 161 patients was divided in a control group and an experimental group, and then state-trait anxiety inventory was applied to both, after the sociodemographic interview and always after the consent of participation of the patient. Results: At a 95 % confidence interval, the intergroup difference between means of state anxiety ranged from -0.929 and -0.810. The value of t student test was -28.701 (df = 159 and 2-tail sig = 0.000). On the other hand, the intergroup difference between means of trait anxiety ranged from -0.141 and -0.022. The value of t student test was -2.722 (df = 159 e 2-tail sig = 0.007). Application of Spearman’s Ro revealed the correlation between values of state and trait anxiety based in a non-normal approximation: for control group 0.409 (sig = 0.000) and for experimental group 0.321 (sig = 0.004), whereas it did not reveal any statistically significant correlation between sociodemographic characteristics and psychometric tests. Conclusion: There exists a significant intergroup difference between the anxiety state and the anxiety trait. A significant correlation is verified between state and trait anxiety within each group, what is not verified between psychometric tests and sociodemographic characteristics.
- As condições sociais das mulheres no século XIXPublication . Anica, AuríziaCom esta comunicação pretende-se demonstrar que a emergência do sufragismo em Portugal compreende-se num processo de «civilização dos costumes» que remonta ao período da monarquia liberal em que mulheres e homens têm um papel ativo. Neste processo as alterações são visíveis a partir de meados do século XIX, acelerando no último quartel do século. Só tornando visíveis as estratégias de resistência à dominação masculina e a modernização da cultura e das relações de género na longa duração é possível compreender a emergência do sufragismo feminista republicano do princípio de novecentos.