Undersampled Critical Branching Processes on Small-World and Random Networks Fail to Reproduce the Statistics of Spike Avalanches

The power-law size distributions obtained experimentally for neuronal avalanches are an important evidence of criticality in the brain. This evidence is supported by the fact that a critical branching process exhibits the same exponent t~3=2. Models at criticality have been employed to mimic avalanche propagation and explain the statistics observed experimentally. However, a crucial aspect of neuronal recordings has been almost completely neglected in the models: undersampling. While in a typical multielectrode array hundreds of neurons are recorded, in the same area of neuronal tissue tens of thousands of neurons can be found. Here we investigate the consequences of undersampling in models with three different topologies (two-dimensional, small-world and random network) and three different dynamical regimes (subcritical, critical and supercritical). We found that undersampling modifies avalanche size distributions, extinguishing the power laws observed in critical systems. Distributions from subcritical systems are also modified, but the shape of the undersampled distributions is more similar to that of a fully sampled system. Undersampled supercritical systems can recover the general characteristics of the fully sampled version, provided that enough neurons are measured. Undersampling in two-dimensional and small-world networks leads to similar effects, while the random network is insensitive to sampling density due to the lack of a well-defined neighborhood. We conjecture that neuronal avalanches recorded from local field potentials avoid undersampling effects due to the nature of this signal, but the same does not hold for spike avalanches. We conclude that undersampled branching-process-like models in these topologies fail to reproduce the statistics of spike avalanches.

Undersampled Critical Branching Processes on Small-World and Random Networks Fail to Reproduce the Statistics of Spike Avalanches

The power-law size distributions obtained experimentally for neuronal avalanches are an important evidence of criticality in the brain. This evidence is supported by the fact that a critical branching process exhibits the same exponent t~3=2. Models at criticality have been employed to mimic avalanche propagation and explain the statistics observed experimentally. However, a crucial aspect of neuronal recordings has been almost completely neglected in the models: undersampling. While in a typical multielectrode array hundreds of neurons are recorded, in the same area of neuronal tissue tens of thousands of neurons can be found. Here we investigate the consequences of undersampling in models with three different topologies (two-dimensional, small-world and random network) and three different dynamical regimes (subcritical, critical and supercritical). We found that undersampling modifies avalanche size distributions, extinguishing the power laws observed in critical systems. Distributions from subcritical systems are also modified, but the shape of the undersampled distributions is more similar to that of a fully sampled system. Undersampled supercritical systems can recover the general characteristics of the fully sampled version, provided that enough neurons are measured. Undersampling in two-dimensional and small-world networks leads to similar effects, while the random network is insensitive to sampling density due to the lack of a well-defined neighborhood. We conjecture that neuronal avalanches recorded from local field potentials avoid undersampling effects due to the nature of this signal, but the same does not hold for spike avalanches. We conclude that undersampled branching-process-like models in these topologies fail to reproduce the statistics of spike avalanches.

Construtivismo de marco teórico-pedagógico a grife: um estudo a partir das mensagens veiculadas na internet

This thesis is resulted of a research on propagated the social representations of constructivism in the Internet, which as had estimated basic the idea of Moscovici (1961) of that the media it has determinative paper in the popularization of the scientific theories, in formation e propagation of the social representations and in the construction of behaviors human beings. Understanding the Internet as latest space of circulation of social communications, therefore, privileged field (and still not explored) for studies of social representations, we choose this half midiático as investigative field of our research, it if it constitutes in the "great ocean of the new informational planet" (LEVY, 2000, p. 126), besides making possible the interaction with different forms of images, different individuals, different ' world ', configuring itself as important space of symbolic production e of analysis of the representational process in the world contemporary. Based in these questions, we trace as objective to analyze the circulating speech propagated on-line on the constructivism, searching to apprehend the social representations shared the respect. This objective was constructed in face of the insertion of the theory constructivist in the educational way has two decades more than, as well as of its consolidation as reference in different social contexts, mainly in midiático. The question that directed the research was: as this theory obtains to penetrate in some layers of our society, to influence the world readings e the behaviors of different people? That modifications it suffers in this trajectory and which the paper of the Internet in this process? The corpus of the research was constituted of the substances on the theory found in the Internet, in pages in Portuguese of Google, in the period of 27 of July of 2004 the 17 of August of 2004. The data they had been analyzed on the basis of the project of analysis of content elaborated for Moscovici (1961) and in the estimated theoreticians of the social communication, in special of the hypermedia. The results had disclosed that the Internet participates of determinative form in the process of popularization of the constructivism theory, not only spreading out its estimated theoretician- methodological for the domain public (diffusion), but propagating positive beliefs and images of its postulates (propagation) and using them it service of interests politicians e financiers (propaganda). The popularization of the constructivism in the Internet and social representations of this theory propagated configure one process in which the theory passes of pedagogical theoretical landmark for grief, assuming a commercial character extremely and the status of solution for problems of the education and the society, stirring up attitudes and behaviors in public, most general possible, that comes to take care of to the interests politicians e marketing. Recognizing the diversity, the permanent renewal of information and the negotiation of directions gifts in the Internet, as well as the innumerable ones forms of access to the information found by it, we consider results of the research as fruits of the inherent characteristics to this way midiático, to the time where we call the attention for relativity these results, for the plasticity of knowing them and sensible propagated on-line e for the great challenge that the hypermedia imposes to the study of communication phenomena, of the social representations and in educational quarrels and for the necessity of new research that they investigate the forms of socialization of the information and communication propitiated by hypermedia and its implications in the construction of the symbolic universes and in practical social

Mulher não vale nem um real : patriarcado nas letras das músicas de forró

Patriarchy is a dominating system that establishes male power in social relations as the social-ideological system and the structuring element of several ways of men‟s domination on gender social relations, on organization of social life, on private relations, and on political decision spaces. In this study we enlarge our reflection about patriarchy from the analysis of Forró lyrics, more specifically the variation known as stylized. Of late decades, it is a kind of music that has been receiving a large acceptance all over the national territory, making use of everyday expressions that propagate and make apology to many forms of discrimination, oppression and violence against women. We emphasize that over this study 14 Forró lyrics were analyzed of different styles besides stylized, like the traditional and the double meaning ones. However, we dwelled on the content analysis, particularly in three Stylized Forró lyrics, they are: Tapa na Cara (2008) by Saia Rodada Band; Mulher Roleira (2004), Aviões do Forró Band; and Bomba no Cabaré (2007), Matruz com Leite Band. In order to make a critical analysis of the elements in the lyrics content, we support ourselves on the theoretic-methodological references of the dialectical materialism, a method that allowed us to get closer to the totality of the reality that includes the popular involvement of the analyzed lyrics in a qualitative way. In that sense, we hold onto the theoretic-methodological categories: gender social relations, patriarchy, violence against women, ideology and cultural industry. As from the lyrics compilation, they were arranged by theme, we classified and analyzed the content, which allowed us to comprehend the messages in the lyrics, beyond the text shows at first sight. Today, there are many mechanisms of propagation and perpetuation of patriarchal ideology. A very relevant mechanism of this phenomenon is the sexual violence. The violence against women is a form to propagate and keep sexism, which may occur in different ways, like physical, psychological, sexual, patrimonial and social. Through our study we established that the propagation of the violence against women as being something natural and banal, giving reinforcement to the asymmetric construction of gender relations that priorizes male to the detriment of female. This banalization is perhaps, one of the strongest allies of this phenomenon‟s perpetuation, that affects women all over the world from different social classes

Conservação de espécies nativas em um assentamento rural do município de Apodi-RN: impactos socioambientais e econômicos e o uso da biotecnologia como alternativa promissora

The Caatinga biome has a high diversity of potential and their conservation constitutes one of the greatest challenges of Brazilian science. The sustainable management of the Caatinga emerges as an alternative that through the formation of systems agrossilvipastoris, enables the use of forest resources sustainably, ensuring their conservation, regeneration and recovery. In RN this technique has been developed mainly in settlements of Agrarian Reform, such as P. A. Moaci Lucena, and their impacts go beyond the environmental aspect and reverberate socially and economically on the quality of life of family farmers. Despite the efficiency of the Sustainable Management of the Caatinga in the conservation of native species, many forests species of this biome faces serious problems of propagation and for this reason have become vulnerable to extinction, as is the case of Mimosa caesalpiniifolia Benth . Thus , it is evident the need to use sustainable alternatives to overcome the difficulties of propagation of this species and enable their replacement in areas where their existence is threatened. The Plant Biotechnology is considered as a promising alternative in this sense, considering that by micropropagation enables the large-scale production of seedlings with high health genetics status. This work has the following objectives: evaluate the perception of family farmers of P. A. Moaci Lucena in relation to social, environmental and economic impacts of the Sustainable Management of the Caatinga and check the conditions of germination and in vitro propagation of Mimosa caesalpiniifolia Benth that enabling the production of seedlings of this specie on a large scale. To achieve the first objective, semi-structured interviews showed that in the perception of farmers PA Moaci Lucena, the Sustainable Management of the Caatinga was responsible for generating many social, environmental and economic impacts that affected directly in the improvement in the quality of life of the families of the Settlement Project Moaci Lucena. Have to achieve the second objective, were investigated the influence of different substrates and concentrations of growth regulator BAP in the germination and shoot induction in vitro of Mimosa caesalpiniifolia Benth. The vermiculite was presented as the most suitable substrate for germination of this species, because it provided a more rapid germination, higher growth rates and higher dry matter accumulation. Regarding micropropagation, the concentration of 17.76 μmol/L of BAP presented a more responsive in relation to multiplication rate and the number of shoots in M. caesalpiniifolia, thus constituting the most suitable concentration for the in vitro propagation of this specie

Modelagem do clima de ondas e seus efeitos sobre as feições morfológicas costeiras no litoral setentrional do Rio Grande do Norte

This thesis presents the results of application of SWAN Simulating WAves Nearshore numerical model, OF third generation, which simulates the propagation and dissipation of energy from sea waves, on the north continental shelf at Rio Grande do Norte, to determine the wave climate, calibrate and validate the model, and assess their potential and limitations for the region of interest. After validation of the wave climate, the results were integrated with information from the submarine relief, and plant morphology of beaches and barrier islands systems. On the second phase, the objective was to analyze the evolution of the wave and its interaction with the shallow seabed, from three transverse profiles orientation from N to S, distributed according to the parallel longitudinal, X = 774000-W, 783000-W e 800000-W. Subsequently, it was were extracted the values of directional waves and winds through all the months between november 2010 to november 2012, to analyze the impact of these forces on the movement area, and then understand the behavior of the morphological variations according to temporal year variability. Based on the results of modeling and its integration with correlated data, and planimetric variations of Soledade and Minhoto beach systems and Ponta do Tubarão and Barra do Fernandes barrier islands systems, it was obtained the following conclusions: SWAN could reproduce and determine the wave climate on the north continental shelf at RN, the results show a similar trend for the measurements of temporal variations of significant height (HS, m) and the mean wave period (Tmed, s); however, the results of parametric statistics were low for the estimates of the maximum values in most of the analyzed periods compared data of PT 1 and PT 2 (measurement points), with alternation of significant wave heights, at times overrated with occasional overlap of swell episodes. By analyzing the spatial distribution of the wave climate and its interaction with the underwater compartmentalization, it was concluded that there is interaction of wave propagation with the seafloor, showing change in significant heights whenever it interacts with the seafloor features (beachrocks, symmetric and asymmetric longitudinal dunes, paleochannel, among others) in the regions of outer, middle and inner shelf. And finally, it is concluded that the study of the stability areas allows identifications of the most unstable regions, confirming that the greatest range of variation indicates greater instability and consequent sensitivity to hydrodynamic processes operating in the coastal region, with positive or negative variation, especially at Ponta do Tubarão and Barra do Fernandes barrier islands systems, where they are more susceptible to waves impacts, as evidenced in retreat of the shoreline

Encapsulamento de solventes em nanotubos de haloisita para promoção de auto-reparo em polímeros

Micro cracking during service is a critical problem in polymer structures and polymer composite materials. Self-healing materials are able to repair micro cracks, thus their preventing propagation and catastrophic failure of structural components. One of the self-healing approaches presented in the literature involves the use of solvents which react with the polymer. The objective of this research is to investigate a procedure to encapsulate solvents in halloysite nanotubes to promote self-healing ability in epoxy. Healing is triggered by crack propagation through embedded nanotubes in the polymer, which then release the liquid sovent into the crack plane. Two solvents were considered in this work: dimethylsulfoxide (DMSO) and nitrobenzene. The nanotubes were coated using the layer-by-layer technique of oppositely charged polyelectrolytes: cetyltrimethylammonium bromide (CTAB) and sodium polyacrylate. Solvent encapsulation was verified by X-ray diffraction (XRD), Fourier transform infrared (FTIR), analysis thermogravimetry (TGA), adsorption and desorption of nitrogen and scanning electron microscopy (SEM). The introduction of the solvent DMSO into the cavity of the nanotubes was confirmed by the techniques employed. However, was not verified with nitrobenzene only promoted clay aggregation. The results suggest that the CTAB reacted with the halloystite to form a sealing layer on the surface of the nanotubes, thus encapsulating the solvent, while this was not verified using sodium polyacrylate.