Contribuições ao estudo das redes complexas: modelo de qualidade

In this work we analyse the implications of using a power law distribution of vertice's quality in the growth dynamics of a network studied by Bianconi anel Barabási. In particular, we start studying the random networks which characterize or are related to some real situations, for instance the tide movement. In this context of complex networks, we investigate several real networks, as well as we define some important concepts in the network studies. Furthermore, we present the first scale-free network model, which was proposed by Barabási et al., and a modified model studied by Bianconi and Barabási, where now the preferential attachment incorporates the different ability (fitness) of the nodes to compete for links. At the end, our results, discussions and conclusions are presented

Efeito in vitro da terapia fotodinâmica sobre bactérias orais em suspensão e na formação de biofilme : ensaio com azul de metileno e toluidina ativados por luz halógena

Photodynamic therapy (PDT) has been proposed as an alternative method for the treatment of biofilm-dependent oral diseases like dental caries. This therapy consists of simultaneous action of a visible light (L) and a photosensitizer (FS) in the presence of oxygen, which leads to production of different reactive oxygen species that can interact with the bacterial cell components, and promote cell death. This study aims to evaluate the antimicrobial action of PDT on oral bacteria in suspension, as well as the formation of mono and multi-species biofilms, in vitro, from a standard strain of Streptococcus mutans (ATCC 25175) and saliva samples, respectively. The dye methylene blue (MB) and toluidine blue (TB) were used at a concentration of 100 mg/ L and activated by halogen light (600 to 750 nm) from a modified hand held photopolymerizer (Ultralux ®, Dabi Atlante, Ribeirão Preto , São Paulo, Brazil.). Planktonic cultures were prepared and submitted to different experimental conditions: 1. PDT using TB 2. PDT using MB, 3. L+ FS- , 4. TB + L - ; 5. MB+ L-; 6. L- FS- (negative control) and 7. administration of 0.12% chlorhexidine digluconate (positive control) (Periogard ®, Colgate-Palmolive Company, New York, USA). The immediate and mediated action of PDT on bacterial suspensions, as well as its effect on biofilm formation were observed from the number of colony-forming units per milliliter (CFU/mL) and measures optical density (OD). The data were statistically analyzed using the Kruskal-Wallis and Mann-Whitney test for the significance level of 5%. According to the results, the PDT showed no antibacterial action on suspensions of S. mutans, regardless of the dye used. PDT with MB activated by halogen light was able to reduce 86.6% CFU/mL multi-species planktonic cultures, however, this reduction was not significant (p > 0.05). PDT showed antibacterial effect, mediate on multi-species planktonic cultures with TB (p < 0.001) and MB (p < 0.001), activated by halogen light. PDT was able to prevent the formation of multispecies biofilm, through the activation of TB by halogen light (p = 0.01). We conclude that activation of the dye toluidine blue and methylene blue, by halogen light (PDT) showed antimicrobial activity, compared to multi-species planktonic cultures prepared from saliva samples

Influência da salinidade e temperatura da água nas respotas comportamental e fisiológica de camarões marinhos Litopenaeus vannamei(BOONE 1931)

The shrimp Litopenaeus vannamei has been grown in highly variable environments, especially in relation to salinity and water temperature. The adjustment to such conditions mainly involves changes in behavior, physiology, particularly in the immune response. This may consequently reduce the welfare of these animals. Despite the widespread farming of the species, little is known about their behavioral and physiological responses under stressful conditions. Thus, the objective of this study was to assess the influence of different salinities and temperatures in the behavior of the marine shrimp L. vannamei, and its relation to the total hemocytes count. In the laboratory, juvenile shrimp were kept in glass aquaria with a closed water recirculation system, continuous aeration and filtration, and under a 12:12 h light/dark cycle. Behavioral observations occurred 1, 4, 7 and 10 h after the start of each phase (light or dark). To assess the influence of salinity, shrimp were first acclimated and then observed at 2, 30 or 50 ppm salinity water, while temperatures tested were 18, 28 and 33 ° C. At the end of each experiment (30 days), shrimp hemolymph was collected for subsequent total hemocytes count (THC), a parameter used to assess stress. In general, feeding behavior was modified under lower salinity and temperature, with reduced values in feeding, exploration and digestive tract filling. Inactivity and burrowing were prevalent under extreme conditions water salinity and temperature, respectively: 2 and 50 ppm and 18 and 33 ° C; crawling was also less frequent under these conditions. In regards to light/dark cycle, shrimp were more active during the dark phase (crawling and swimming), while burrowing was higher during the light phase, regardless of salinity or temperature of the water. Inactivity behavior did not vary according to the light/dark cycle. Moreover, the total hemocytes count (THC) was reduced under 2 and 50 ppm salinity and 18 ° C temperature. Farming of L. vannamei under extremely low or high salinities and low temperatures is harmful. This suggests the species must be cultivated in salinities closer to those of the sea as well as at high temperatures, which seems to be ideal for a management focused on animal welfare, therefore, producing healthier shrimp

Taxa de disparo e ativação de assembléias no hipocampo de ratos durante o processamento de uma memória aversiva

Hebb postulated that memory could be stored thanks to the synchronous activity of many neurons, building a neural assembly. Knowing of the importance of the hippocampal structure to the formation of new explicit memories, we used electrophysiological recording of multiple neurons to access the relevance of rate coding from neural firing rates in comparison to the temporal coding of neural assemblies activity in the consolidation of an aversive memory in rats. Animals were trained at the discriminative avoidance task using a modified elevated plus-maze. During experimental sessions, slow wave sleep periods (SWS) were recorded. Our results show an increase in the identified neural assemblies activity during post-training SWS, but not for the neural firing rate. In summary, we demonstrate that for this particular task, the relevant information needed for a proper memory consolidation lies within the temporal patters of synchronized neural activity, not in its firing rate

Expressão de zif-268 durante a aquisição, evocação e extinção de uma memória aversiva

In the behavioral paradigm of discriminative avoidance task, both short and long-term memories have been extensively investigated with behavioral and pharmacological approaches. The aim of the present study was to evaluate, using the abovementioned model, the hippocampal expression of zif-268 - a calcium-dependent immediate early gene involved with synaptic plasticity process - throughout several steps of memory formation, such as acquisition, evocation and extiction. The behavioral apparatus consisted of a modified elevaated plus-maze, with their enclosed arms disposed in "L". A pre-exposure to the maze was made with the animal using all arms enclosed, for 30 minutes, followed by training and test, during 10 minutes each. The between sections interval was 24h. During training, aversive stimuli (bright light and loud noise) were actived whenever the animals entered one of the enclosed armas (aversive arm). Memory acquisiton, retention and extinction were evaluated by the percentage of the total time spent exploring the aversive arm. The parameters evaluated (time spent in the arms and total distance traveled) were estimated with an animal tracking software (Anymaze, Stoelting, USA). Learning during training was estimated by the decrease of the time spent exploring the aversive arm. One hour after the beginning of each section, animals were anaesthetized with sodium-thiopental (i.p.) and perfused with 0.9% heparinized saline solution followed by 4% paraformaldehyde. Brains were cryoprotected with 20% sucrose, separeted in three blocks and frozen. The middle block, containing the hippocampus, was sectioned at 20 micro meters in the coronal plane and the resutant sections were submitted to zif-268 immunohistochemistry. Our results show an increased expression of zif-268 in the dentate gyrus (DG) during the evocation and extinction stages. There is a distinct participation of the DG during the memory evocation, but not during its acquisition. Inaddition, all hippocampal regions (CA1, CA3 and DG) presented an increased zif-268 expression during the process of extinction.

Desenvolvimento de componentes nanométricos para aplicação em células a combustível à base de sólidos estruturados e filmes finos

The present work aims the preparation of filmes of strontium-doped lanthanum manganite (perovskita) yttria-stabilized zirconia (LSM-SDC) films deposited on substrate of YSZ by means of spin coating technique having as principal objective their application to solid oxide fuel cells of intermediate temperature. La0,8Sr0,2MnO3 and Ce0,8Sm0,2O1,9 were obtained by modified Pechini method by use of gelatin which act as polymerization agent. The powders obtained were characterized by Xray fluorescence, X ray diffraction, electronic scanning microscopy and the superficial area by BET method. The results obtained by X-ray fluorescence showed that the route adopted for obtention of powders was effective in the obtention of the compositions with close values to the stoichiometrics. Ethyl cellulose was used as pore-forming agent and mixed with the LSM-SDC powders in weight proportions of 1:24, 2:23 and 1:9. The films were sintered at 1150 °C for 4 h and characterized by X-ray diffraction and scanning electron microscopy technique (SEM) and atomic force. The phases quantification of the precursory powders and of the obtained films was carried through Rietveld method. According with the analysis of SEM, as the content of ethyl cellulose was increased, the pore distribution in films become more uniform and the pore size reduced. The methodology used for the obtention of the films was very efficient, considering a material was obtained with characteristics that were proper to the application as electrolyte/cathode system to solid oxide fuel cells

Confecção e caracterização físico-química de filmes compósitos autossustentáveis NaAlg-TiO2-WO3

A new self-sustainable film was prepared through the sol-gel modified method, previously employed in our research group; sodium alginate was used as the polymer matrix, along with plasticizer glycerol, doped with titanium dioxide (TiO2) and tungsten trioxide (WO3). By varying WO3 concentration (0,8, 1,6, 2,4 and 3,2 μmol) and keeping TiO2 concentration constant (059 mmol), it was possible to study the contribution of these oxides on the obtained films morphological and electrical properties. Self-sustainable films have analyzed by Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XDR), Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDS) and Electrochemical Impedance Spectroscopy (EIS). By the IR specters, it was possible identify the TiO2, and posteriorly WO3, addition has provided dislocation of alginate characteristics bands to smaller vibrations frequencies indicating an electrostatic interaction between the oxides and the polymer matrix. Diffractograms show predominance of the amorphous phase in the films. SEM, along with EDX, analysis revealed self-sustainable films showed surface with no cracks and relative dispersion of the oxides throughout the polymer matrix. From Impedance analysis, it was observe increasing WO3 concentration to 2,4 μmol provided a reduction of films resistive properties and consequent improvement of conductive properties

Culinária do Seridó: um elemento da identidade territorial

This work aims to analyze the local cuisine as an element of territorial identity from Seridó Rio Grande do Norte State in the contemporaneousness - XXI century, where it takes place one motion, seemly contradictory, yet dialogical, in the way of eating locally is modified by food diversity and yet is lauded as an element of resistance, that is, of identification. Based on the perspective that groups go over time outlining on the territory their eating cultural characteristics, we have noticed that the spatiality from the local cuisine has happened during the territorial structuring process, being susceptible to the social, economical and technological changes, that hover over this space. On the unfolding days it was created a whole semiology around the cookery , incorporating to its territory of living, symbols, images, knowledge, tastes, feelings and smells that legitimate a way of being, better saying, of eating. But not all of the plates that congregate these aspects, only the oldest, the most emblematic. Within the diverse intercrossing of culture at Seridó region, they are the ones that maintain the vinculum from the group with its culture and with its territory, reminding what they are, or at least what they were, conferring them a legitimacy before those to whom they relate. The cookery from the Seridó region, this way is a cultural geo-symbol that turn this space significant and visible, for ordering the inside characteristics from the group before the new socio-cultural models present in the territory