Quantitative evaluation of geodiversity : development of methodological procedures with application to territorial management

Although geodiversity is considered the setting for biodiversity, there is still a huge gap in the social recognition of these two concepts. The concept of geodiversity, less developed, is now making its own way as a robust and fundamental idea concerning the abiotic component of nature. From a conservationist point of view, the lack of a broader knowledge concerning the type and spatial variation of geodiversity, as well as its relationship with biodiversity, makes the protection and management of natural or semi-natural areas incomplete. There is a growing need to understand the patterns of geodiversity in different landscapes and to translate this knowledge for territorial management in a practical and effective point of view. This kind of management can also represent an important tool for the development of sustainable tourism, particularly geotourism, which can bring benefits not only for the environment, but also for social and economic purposes. The quantification of geodiversity is an important step in all this process but still few researchers are investing in the development of a proper methodology. The assessment methodologies that were published so far are mainly focused on the evaluation of geomorphological elements, sometimes complemented with information about lithology, soils, hidrology, morphometric variables, climatic surfaces and geosites. This results in very dissimilar areas at very different spatial scales, showing the complexity of the task and the need of further research. This current work aims the development of an effective methodology for the assessment of the maximum elements of geodiversity possible (rocks, minerals, fossils, landforms, soils), based on GIS routines. The main determinant factor for the quantitative assessment is scale, but other factors are also very important, such as the existence of suitable spatial data with sufficient degree of detail. It is expected to attain the proper procedures in order to assess geodiversity at different scales and to produce maps with the spatial representation of the geodiversity index, which could be an inestimable contribute for land-use management

Minimal model for calcium alternans due to SR release refractoriness

In the heart, rapid pacing rates may induce alternations in the strength of cardiac contraction, termed pulsus alternans. Often, this is due to an instability in the dynamics of the intracellular calcium concentration, whose transients become larger and smaller at consecutive beats. This alternation has been linked experimentally and theoretically to two different mechanisms: an instability due to (1) a strong dependence of calcium release on sarcoplasmic reticulum (SR) load, together with a slow calcium reuptake into the SR or (2) to SR release refractoriness, due to a slow recovery of the ryanodine receptors (RyR2) from inactivation. The relationship between calcium alternans and refractoriness of the RyR2 has been more elusive than the corresponding SR Ca load mechanism. To study the former, we reduce a general calcium model, which mimics the deterministic evolution of a calcium release unit, to its most basic elements. We show that calcium alternans can be understood using a simple nonlinear equation for calcium concentration at the dyadic space, coupled to a relaxation equation for the number of recovered RyR2s. Depending on the number of RyR2s that are recovered at the beginning of a stimulation, the increase in calcium concentration may pass, or not, over an excitability threshold that limits the occurrence of a large calcium transient. When the recovery of the RyR2 is slow, this produces naturally a period doubling bifurcation, resulting in calcium alternans. We then study the effects of inactivation, calcium diffusion, and release conductance for the onset of alternans. We find that the development of alternans requires a well-defined value of diffusion while it is less sensitive to the values of inactivation or release conductance.Postprint (author's final draft

Instability and Spatiotemporal Dynamics of Alternans in Paced Cardiac Tissue

We derive an equation that governs the spatiotemporal dynamics of small amplitude alternans in paced cardiac tissue. We show that a pattern-forming linear instability leads to the spontaneous formation of stationary or traveling waves whose nodes divide the tissue into regions with opposite phase of oscillation of action potential duration. This instability is important because it creates dynamically an heterogeneous electrical substrate for inducing fibrillation if the tissue size exceeds a fraction of the pattern wavelength. We compute this wavelength analytically as a function of three basic length scales characterizing dispersion and inter-cellular electrical coupling.Comment: 4 pages, 3 figures, submitted to PR

A negative mass theorem for surfaces of positive genus

We define the "sum of squares of the wavelengths" of a Riemannian surface (M,g) to be the regularized trace of the inverse of the Laplacian. We normalize by scaling and adding a constant, to obtain a "mass", which is scale invariant and vanishes at the round sphere. This is an anlaog for closed surfaces of the ADM mass from general relativity. We show that if M has positive genus then on each conformal class, the mass attains a negative minimum. For the minimizing metric, there is a sharp logarithmic Hardy-Littlewood-Sobolev inequality and a Moser-Trudinger-Onofri type inequality.Comment: 8 page

Determinação de métodos para avaliação da resistência à murcha bacteriana em pimenta longa (Piper hispidinervum).

A murcha-bacteriana, causada por Ralstonia solanacearum, ocorre em todas as regiões do Brasil, principalmente nos lugares de altas temperatura e umidade, associada a um grande número de plantas cultivadas e plantas invasoras. A murcha-bacteriana foi recentemente encontrada infectando pimenta longa (Piper hispidinervum), planta arbustiva, nativa do Estado do Acre, que atualmente vem sendo cultivada comercialmente para extração do óleo essencial safrol, utilizado nas formulações de inseticidas biodegradáveis com baixa toxicidade e como fixador de fragrâncias e cosméticos. O presente trabalho teve como objetivo estudar dois métodos para avaliação da resistência à murcha-bacteriana em pimenta longa em condições de casa de vegetação

Avaliação de híbridos comerciais de milho em áreas de arroz irrigado no Rio Grande do Sul. 2000/01 e 2001/02.

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Seleção de porta-enxertos de citros mediante desenvolvimento do sistema radicular com ênfase na tolerância à seca

Desenvolvimento de Variedade

Monitorización de los niveles de inmisión de COVs en el aire ambiente de la Isla de Tenerife

Ponencia presentada en: 1er Encuentro sobre Meteorología y Atmósfera de Canarias, celebrado en el Puerto de la Cruz, los días 12,13 y 14 de noviembre de 2003. El encuentro estuvo organizado por el Centro Meteorológico Territorial en Canarias Occidental, con la colaboración del Observatorio Atmosférico de Izaña y del Grupo de Física de la Atmósfera de la Facultad de Física (Universidad de La Laguna