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Comparisons and Contrasts between Asymmetry and Nestedness in Interacting Ecological Networks  [PDF]
Gilberto Corso, N. F. Britton
Open Journal of Ecology (OJE) , 2014, DOI: 10.4236/oje.2014.411055

We compare and contrast asymmetry and nestedness, two concepts used in the characterisation of the specialist-generalist balance in bipartite ecological interaction networks. Our analysis is relevant to mutualistic networks such as those consisting of flowering plants and pollinators, or fruiting plants and frugivores, or antagonistic networks such as those consisting of plants and herbivores, in an ecological community. We shall refer to the two sets of species in the bipartite network as plants and animals, the usual but not the only ecological situation. By asymmetry we mean either connectivity asymmetry or dependence asymmetry, which are essentially equivalent. Asymmetry expresses two attributes: generalists interact preferentially with specialists, and specialists avoid interacting with each other. Nested patterns, in principle, should express these same two features and one more: the presence of a core of interactions among generalists. We compute the full set of perfectly nested patterns that are possible in an L × L matrix with N interactions representing an ecological network of L plants and L animals, and point out that the number of nested arrangements grows exponentially with N. In addition, we analyse asymmetry for the full set of perfectly nested patterns, and identify extremes of asymmetry inside the universe of nested patterns. The minimal asymmetry is marked by a modular core of interactions between species that are neither specialists nor generalists. On the other hand, the case of maximal asymmetry is formed by a set of few generalists and many specialists with equal connectivity. The stereotypic case of nestedness with a core of interactions among generalists has intermediate asymmetry.

Dise?o de una turbina de torsión, para contrarrestar el torque generado por una maquina rotativa de base flotante libre
Universidad, Ciencia y Tecnología , 2009,
Abstract: for the purpose of widening the knowledge in the engineering field, this research provides a guide for the design of an air turbine to oppose torsion based on a parametric model that can explain, through its design based on classical laws of conservation of the linear momentum, the behavior of this kind of turbine. the objective of the design is to provide an effective way to stabilize a rotating machine mounted on a free floating base. the results indicate the possibility of establishing a method to determine a mathematical model that will establish the relationship between torque, angular velocity and number of blades of a turbine with flat uniform blades. it also indicates the possibility of reducing the relationship that determines the optimal number of blades to achieve a predetermined maximum momentum. since the mathematical model may be experimentally tested, the feasibility of the design can be assured.
Exercise and cognitive function: a hypothesis for the association of type II diabetes mellitus and Alzheimer's disease from an evolutionary perspective
Gilberto NO Brito
Diabetology & Metabolic Syndrome , 2009, DOI: 10.1186/1758-5996-1-7
Abstract: The great evolutionary biologist Theodosius Dobzhansky once said: "Nothing in biology makes sense except in the light of evolution". Along this line, I will put forward a hypothesis for the association of type II diabetes mellitus (DM2) and Alzheimer disease (AD) from an evolutionary perspective. This hypothesis contends that the close interplay between physical activity/exercise and cognitive function was selected for during the course of evolution, but the absence of sufficient physical activity typical of modern societies provoked a rupture of the evolutionary relationship of exercise and cognitive function thereby producing the fundamental metabolic features of DM2 which in the brain over a protracted time span lead to the neuropathology of AD. I will begin by posing the issue of the association of DM2 and AD and then proceed with a brief review of the endurance running hypothesis for the evolution of man. Next, the neurobiological and neurobehavioral effects of exercise/physical activity will be discussed and then I will present the hypothesis. Lastly, directions for further research on the basis of the hypothesis will be suggested.Although both physical activity and exercise involve bodily movement produced by skeletal muscles, exercise, but not physical activity, incorporates a goal for the physical activity namely to improve or maintain physical fitness. Be that as it may, in the present paper physical activity and exercise will be used interchangeably.DM2 and AD are common in the elderly population the world over. Since these two disorders are both chronic and progressive, their combined economic burden on society has skyrocketed pari passu with the aging of the population. Therefore, DM2 and AD have become two of the most important diseases in the geriatric health care practice.The prevalence of DM2 in people older than 65 years in Western societies is 8.5% [1] and the corresponding figure for AD is about 30.0% at 80 years [2]. Thus, the prevalence rates o
O mito do progresso
Dupas, Gilberto;
Novos Estudos - CEBRAP , 2007, DOI: 10.1590/S0101-33002007000100005
Abstract: progress is a myth renewed by an ideological apparatus whose effort is to persuade that history has a glorious fate. the article analyzes who is favored by progress, the risks to society, environment and for humankind as a hole. it also tries to point out elements to the deconstruction of hegemonic discourse about globalization.
Alfabetiza??o científica e forma??o profissional
Lacerda, Gilberto;
Educa??o & Sociedade , 1997, DOI: 10.1590/S0101-73301997000300006
Abstract: this article analyses the concept of "scientific literacy" in the context of technical education. first, we present some previsions about new technological society and its repercussions on work. then, we characterize "scientific literacy" and identify the relationship between this concept and the characteristics of a middle level professional knowledge. we conclude with a general reflection on personal valorization, technical education and "scientific literacy".
Pedagogía teatral: ruptura, movimiento e inquietud de sí
Educación y Educadores , 2009,
Abstract: this article examines the conditions surrounding the possibility and emergence of theatre pedagogy, understood as a kind of restlessness of self. in doing so, it analyzes stanislavski's pedagogy as an ethic of restlessness of self and one that finds echoes in foucault's analysis of restlessness of self in classical antiquity. in the company of the french philosopher and inspired by his notion of problems, it tries to apply his analysis to ancient texts, especially that of alcibiades and later works, weaving those notions into stanislavski's work. contemporary conditions for theatre pedagogy are suggested, raising questions that help to understand it as an art of existence.
A lógica da economia global e a exclus?o social
Dupas, Gilberto;
Estudos Avan?ados , 1998, DOI: 10.1590/S0103-40141998000300019
Abstract: continuous global advances in technology have apparently failed to ensure to future societies the ability to create flexible jobs exclusively through the use of market mechanisms, commanding income levels and being of such character that are compatible with the basic needs of the world population. the logic behind globalization and the segmentation of productive chains have, in part, absorbed pockets of cheap labor throughout the world without necessarily providing their workers with higher income levels. formal employment is growing at a lower rate than direct investments. if, on the one hand, there are emerging and well compensated opportunities in the flexible labor market, on the other, the informal sector also spans precarious, insecure jobs and poverty. in the peripheral countries, particularly, governments - which are commited to stability - simplely do not have the funding and sufficiently effective structures to ensure the survival of the newly excluded. the employment paradigm is undergoing a definite shift, and there are myriad reasons for concern about the future of social exclusion in the new millenium.
"O Brasil n?o é só doen?a": o programa de saúde pública de Juscelino Kubitschek
Hochman, Gilberto;
História, Ciências, Saúde-Manguinhos , 2009, DOI: 10.1590/S0104-59702009000500015
Abstract: analyzes the public health program that juscelino kubitschek presented while running for president and its dialogue with interpretations that identified brazil as an ailing country that should be recovered through public medicine. the proposals and goals contained in kubitschek's healthcare program, as released during his 1955 campaign, serve as the main sources for this analysis. they also were key to establishing this dialogue, which was both prompted and shaped by a national and international context characterized by the post-war idea of development and public health optimism. within the context of his development project, the article looks at how kubitschek elaborated the themes of the centrality of rural endemic disease and the abandonment of the rural worker, both dear to the sanitary movement in the 1910s. it also underscores how kubitschek the candidate endeavored to link health and development within this arena of government policy.
Logo ali, no final da avenida: Os sert?es redefinidos pelo movimento sanitarista da Primeira República
Hochman, Gilberto;
História, Ciências, Saúde-Manguinhos , 1998, DOI: 10.1590/S0104-59701998000400012
Abstract: between 1910 and 1920, the brazilian sanitation movement endeavored to redefine the boundaries between backlands and coast, interior and cities, rural brazil and urban brazil, in accordance with what sanitarians then deemed the nation?s key problem: public health. the movement relentlessly defended an essentially medical-political definition of these borders: in the eyes of sanitarian physicians, the backlands were characterized by the absence of government and the omnipresence of endemic diseases. through an intensive public opinion campaign, doctors and sanitarians convinced the political elites that the backlands were closer than they thought. this rural sanitation drive had political consequences: it laid the foundations for the first public health initiatives of national scope during the 1920s.
Metrópole, cosmopolitismo e media??o
Velho, Gilberto;
Horizontes Antropológicos , 2010, DOI: 10.1590/S0104-71832010000100002
Abstract: this article deals with questions concerning the relations between metropolitan life and cosmopolitanism. it mentions historical examples and examines contemporary situations, exploiting recent changes in world life. it also deals with the themes of social-cultural complexity, heterogeneity, mediation, multiculturalism and it is implications for different life styles. one of its main concerns, focalizing especially urban life, is the general question of social interaction and sociability as a basic phenomenon for social and historical processes.
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