420 research outputs found

    Higher Order Asymptotics of Decaying Solutions of some Generalized Burgers Equations

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    We study the large-time behavior of solutions to a generalized Burgers Equation, with initial zero mass data. Our main purpose is to present a modified version of the Renormalization Group map, which is able to provide the higher order asymptotic properties of the solution to the Cauchy problem of a class of nonlinear time-evolution problems.Comment: 25 page

    Perfil Ictiofaunístico de duas Lagoas no Rio Paraná, Região do Parque Nacional de Ilha Grande - PR

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    O Rio Paraná é o décimo maior do mundo em descarga e nele se encontra a região do Parque Nacional de Ilha Grande, que é formada por um conjunto de ilhas, lagoas e várzeas periodicamente alagadas, sendo estas de extrema importância para os peixes, servindo de refúgio contra predação, berçário natural e áreas de alimentação para muitas espécies de peixes. Este artigo apresenta um levantamento icitiofaunístico nas lagoas Saraiva e São João, situadas no Parque Nacional de Ilha Grande, com enfoque nas variações espaço-temporais, na composição específica e estrutura etária das assembléias de peixes, sendo que estes foram amostrados em coletas trimestrais, utilizando-se redes de espera de diferentes malhagens. Em termos de número de indivíduos capturados e proporção, tem-se 54% das espécies pertencentes a ordem Characiformes, 42% a Siruliformes, 3% a Perciformes. Rajiformes e Gymnotiformes contribuíram com menos de 1,5% do total das capturas. Na lagoa Saraiva foram capturadas 34 espécies pertencentes a cinco ordens e 17 famílias, destacando-se numericamente Loricariichthys platymetopon, Raphiodon vulpinus, Serrasalmus marginatus e Plagioscion squamosissimus. As maiores contribuições em peso foram proporcionadas por R. vulpinus, Potanotrygon motoro, P. squamosissimus e S. marginatus. Na lagoa São João ocorreram 46 espécies pertencentes a cinco ordens e 17 famílias, destacando-se em número L. platymetopon, Acestrohynchus lacustris, Serrasalmus spilopleura e S. marginatus. Em peso, Prochilodus lineatus, A. lacustris, L. platymetopon e Serrasalmus spilopleura foram as mais representativas. Destaca-se que a maioria das espécies registradas em ambas as lagoas são típicas de ambientes lênticos, utilizando esses locais para seu desenvolvimento e crescimento

    Consumption habits and knowledge level on food packaging of a sample of the Portuguese population

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    As embalagens alimentares têm como principal função a proteção dos alimentos de fatores que alterem o seu valor nutricional, as suas propriedades organoléticas e coloquem em risco a sua segurança. Contudo, os materiais utilizados nas embalagens podem interagir com os alimentos, podendo ocorrer a migração de determinados compostos para os alimentos. A maioria das embalagens metálicas usadas nas conservas de alimentos são revestidas internamente por um material epóxi-fenólico, onde se inclui o éter diglicidílico do bisfenol A (BADGE). Nas últimas décadas, tem havido um grande desenvolvimento das tecnologias usadas na conservação dos alimentos, com consequente aumento do tempo de vida útil destes e da segurança alimentar. Neste sentido, surgiram as embalagens ativas e as embalagens inteligentes. Este estudo teve como objetivo avaliar os hábitos de consumo de latas de conserva numa amostra da população portuguesa e aferir o seu conhecimento sobre embalagens ativas e inteligentes. Perante os resultados obtidos, a população portuguesa consome um elevado número de produtos em latas de conserva, em especial atum (género Thunnus), e poucos inquiridos (26,4%) possuem conhecimento sobre a potencial migração de bisfenóis para os alimentos. Em relação às embalagens alimentares inovadoras, apenas uma pequena fração dos inquiridos (11%) tem conhecimento da sua existência e das funções que desempenham.The main purpose of food packaging is to protect food from factors that alter its nutritional value, its organoleptic proper ties and put its safety at risk. However, the materials used in the packaging may interact with food, and migration of cer tain compounds to food may occur. Most metal containers used in food preser ves are internally coated with an epoxyphenolic material, which includes bisphenol A diglycidyl ether (BADGE). In the last decades, there has been a great development of the technologies used in food preser vation, with a consequent increase in shelf life and food safety. In this sense, active packaging and smar t packaging have emerged. The purpose of this study was to evaluate the consumption habits of canned tins, in a sample of the Por tuguese population, and to gauge their knowledge about active and intelligent packaging. Given the results obtained, the Por tuguese population consumes a large number of canned products, especially tuna fish (Thunnus genus), and few respondents (26.4%) are aware of the potential migration of bisphenols into food. In relation to innovative food packaging, only a small fraction of the respondents (11%) is aware of their existence and the functions they per form.info:eu-repo/semantics/publishedVersio

    Phase behaviour and miscibility studies of collagen/silk fibroin macromolecular system in dilute solutions and solid state

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    Miscibility is an important issue in biopolymer blends for analysis of the behavior of polymer pairs through the detection of phase separation and improvement of the mechanical and physical properties of the blend. This study presents the formulation of a stable and one-phase mixture of collagen and regenerated silk fibroin (RSF), with the highest miscibility ratio between these two macromolecules, through inducing electrostatic interactions, using salt ions. For this aim, a ternary phase diagram was experimentally built for the mixtures, based on observations of phase behavior of blend solutions with various ratios. The miscibility behavior of the blend solutions in the miscible zones of the phase diagram was confirmed quantitatively by viscosimetric measurements. Assessing the effects of biopolymer mixing ratio and salt ions, before and after dialysis of blend solutions, revealed the importance of ion-specific interactions in the formation of coacervate-based materials containing collagen and RSF blends that can be used in pharmaceutical, drug delivery, and biomedical applications. Moreover, the conformational change of silk fibroin from random coil to beta sheet, in solution and in the final solid films, was detected by circular dichroism (CD) and Fourier transform infrared spectroscopy (FTIR), respectively. Scanning electron microscopy (SEM) exhibited alterations of surface morphology for the biocomposite films with different ratios. Surface contact angle measurement illustrated different hydrophobic properties for the blended film surfaces. Differential scanning calorimetry (DSC) showed that the formation of the beta sheet structure of silk fibroin enhances the thermal stability of the final blend films. Therefore, the novel method presented in this study resulted in the formation of biocomposite films whose physico-chemical properties can be tuned by silk fibroin conformational changes by applying different component mixing ratios228sem informaçãosem informaçã

    Dataset after seven years simulating hybrid energy systems with Homer Legacy

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    Homer Legacy software is a well-known software for simulation of small hybrid systems that can be used for both design and research. This dataset is a set of files generated by Homer Legacy bringing the simulation results of hybrid energy systems over the last seven years, as a consequence of the research work led by Dr. Alexandre Beluco, Federal University of Rio Grande do Sul, in southern Brazil. The data correspond to twelve papers published in the last seven years. Two of them describe hydro PV hybrid systems with photovoltaic panels operating on the water surface of reservoirs. One of these twelve papers suggests the modeling of hydropower plants with reservoirs and the other the modeling of pumped hydro storage, and a third still uses these models in a place that could receive both the two types of hydroelectric power plant. The other simulated hybrid systems include wind turbines, diesel generators, batteries, among other components. This data article describes the files that integrate this dataset and the papers that have been published presenting the hybrid systems under study and discussing the results. The files that make up this dataset are available on Mendeley Data repository at https://doi.org/10.17632/ybxsttf2by.2

    PEDOT:PSS-coated polybenzimidazole electroconductive nanofibers for biomedical applications

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    Bioelectricity drives several processes in the human body. The development of new materials that can deliver electrical stimuli is gaining increasing attention in the field of tissue engineering. In this work, novel, highly electrically conductive nanofibers made of poly [2,20 - m-(phenylene)-5,50 -bibenzimidazole] (PBI) have been manufactured by electrospinning and then coated with cross-linked poly (3,4-ethylenedioxythiophene) doped with poly (styrene sulfonic acid) (PEDOT:PSS) by spin coating or dip coating. These scaffolds have been characterized by scanning electron microscopy (SEM) imaging and attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy. The electrical conductivity was measured by the four-probe method at values of 28.3 S·m−1 for spin coated fibers and 147 S·m−1 for dip coated samples, which correspond, respectively, to an increase of about 105 and 106 times in relation to the electrical conductivity of PBI fibers. Human bone marrow-derived mesenchymal stromal cells (hBM-MSCs) cultured on the produced scaffolds for one week showed high viability, typical morphology and proliferative capacity, as demonstrated by calcein fluorescence staining, 40 ,6-diamidino-2-phenylindole (DAPI)/Phalloidin staining and MTT [3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide] assay. Therefore, all fiber samples demonstrated biocompatibility. Overall, our findings highlight the great potential of PEDOT:PSS-coated PBI electrospun scaffolds for a wide variety of biomedical applications, including their use as reliable in vitro models to study pathologies and the development of strategies for the regeneration of electroactive tissues or in the design of new electrodes for in vivo electrical stimulation protocols.info:eu-repo/semantics/publishedVersio

    Evolution of critically ill patients with gastroschisis from three tertiary centers

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    OBJECTIVES AND INTRODUCTION: Gastroschisis is a congenital abdominal wall defect with increasing occurrence worldwide over the past 20-30 years. Our aim was to analyze the morbidity of newborns after gastroschisis closure, with emphasis on metabolic and hydroelectrolyte disturbances in patients at three tertiary university centers. METHODS: From January 2003 to June 2009, the following patient data were collected retrospectively: (A) Background maternal and neonatal data: maternal age, prenatal diagnosis, type of delivery, Apgar scores, birth weight, gestational age and sex; (B) Surgical modalities: primary or staged closure; and (C) Hospital course: levels of serum sodium and levels of serum albumin in the two first postoperative days, number of ventilation days, other postoperative variables and survival. Statistical analyses were used to examine the associations between some variables. RESULTS: 163 newborns were included in the study. Primary closure of the abdominal defect was performed in 111 cases (68.1%). The mean serum sodium level was 127.4¡6.7 mEq/L, and the mean serum albumin level was 2.35¡0.5 g/dL. Among the correlations between variables, it was verified that hyponatremia and hypoalbuminemia correlated with the number of days on the ventilator but not with the number of days on total parenteral nutrition (TPN); mortality rate correlated with infection. The final survival rate was 85.9%. CONCLUSION: In newborns with gastroschisis, more aggressive attention to hyponatremia and hypoalbuminemia would improve the outcome

    Potential application of gelatin scaffolds prepared through in situ gas foaming in skin tissue engineering

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    Gelatin’s excellent foaming ability allows the application of in situ gas foaming as a preparation technique for porous scaffold development. Here, a new iterative experimental design for in situ gas foaming method is reported. The prepared scaffolds were studied for applying the findings to the future skin tissue engineering scaffolds. The thermal stability, mechanical properties, and pore structure of the scaffolds are reported and their degradation resistance by using collagenase enzyme and their cytotoxicity by using fibroblasts were studied. The results of this study demonstrated that gas foaming method can be modified to produce an interconnected porous structure with enhanced mechanical properties

    Reducing discomfort while measuring crown Á heel length in neonates

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    Abstract Aim: To assess the degree of discomfort caused by length measurement in neonates, performed with one or both lower limbs extended, on the first and second day after birth, with either one or both lower limbs extended. Methods: Healthy full-term neonates were systematically sampled during the months of February and March 2004. Crown Áheel length was measured, using a 1-mm precision neonatometer, at approximately 8 h and 32 h after birth, with one and both lower limbs extended. The Neonatal Facial Coding System was used to assess discomfort during measurements. Data were analysed by parametric and non-parametric tests as appropriate. Results: Whatever the measurement technique, discomfort scores are significantly higher during the length measurement than at baseline. Whenever length measurements are performed, discomfort scores are significantly higher when extending both lower limbs rather than one lower limb (p B/0.006). The measured length is greater with one lower limb extended; however, the difference decreases over time, being 0.19 cm (95% CI 0.1 Á0.3; p B/0.001) at approximately 32 h of age. No significant differences in length were found between measurements at approximately 8 or 32 h, regardless of the technique used. The best correlation between length measurements with one or both lower limbs extended was observed at approximately 32 h after birth (r 0/0.98). Conclusion: Measuring crown Áheel length is a distressful procedure for the neonate. Measurements with one lower limb extended result in less discomfort than when both lower limbs are extended, without decreasing the accuracy
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