Analytical approach to directed sandpile models on the Apollonian network

We investigate a set of directed sandpile models on the Apollonian network, which are inspired on the work by Dhar and Ramaswamy (PRL \textbf{63}, 1659 (1989)) for Euclidian lattices. They are characterized by a single parameter $q$, that restricts the number of neighbors receiving grains from a toppling node. Due to the geometry of the network, two and three point correlation functions are amenable to exact treatment, leading to analytical results for the avalanche distributions in the limit of an infinite system, for $q=1,2$. The exact recurrence expressions for the correlation functions are numerically iterated to obtain results for finite size systems, when larger values of $q$ are considered. Finally, a detailed description of the local flux properties is provided by a multifractal scaling analysis.Comment: 7 pages in two-column format, 10 illustrations, 5 figure

Comparison of fluorescent bands during staining of statoliths of the squid Loligo forbesi (Cephalopoda : Loliginidae)

info:eu-repo/semantics/publishedVersio

Levels of Concentrate for Grazing Nelore Crossbred Steers in the Dry Period of the Year in Brazil

In Brazil, the fattening of supplemented grazing steers accounts for many finished animals in the dry season. This work had the objective of evaluating the effect of levels of concentrate on the fattening of crossbred Nelore steers grazing Brachiaria brizantha pasture in the dry period of the year

Motivation in mechanics of materials classes: An experimental approach

Motivation in mechanics of materials classes: An experimental approachThis work presents a novel didactic methodology for the approximation of the students to the subject of Mechanics of Materials, with the aim of improving the understanding of the inertia moment, and its relevance on the mechanical behaviour of structures. The students have grouped on groups of two to three persons. The work consisted in designing the most efficient beam having in mind several design constraints. Tensile tests were performed to determine the relevant material properties. Those were used for the analytic dimensioning of the beams. The aim of the work is to obtain the highest efficiency possible, since it results in the best mark, as possible. The efficiency was measured by the maximum load on experimental bending testing, divided by the mass of the beam. The results, as well as the interest of the methodology are discussed. It is proved that this methodology can be useful for the students to apply theoretical concepts and, at the same time, to give a deeper understanding of real experimental tests.(undefined)info:eu-repo/semantics/publishedVersio

Non-Newtonian fluid flow through three-dimensional disordered porous media

We investigate the flow of various non-Newtonian fluids through three-dimensional disordered porous media by direct numerical simulation of momentum transport and continuity equations. Remarkably, our results for power-law (PL) fluids indicate that the flow, when quantified in terms of a properly modified permeability-like index and Reynolds number, can be successfully described by a single (universal) curve over a broad range of Reynolds conditions and power-law exponents. We also study the flow behavior of Bingham fluids described in terms of the Herschel-Bulkley model. In this case, our simulations reveal that the interplay of ({\it i}) the disordered geometry of the pore space, ({\it ii}) the fluid rheological properties, and ({\it iii}) the inertial effects on the flow is responsible for a substantial enhancement of the macroscopic hydraulic conductance of the system at intermediate Reynolds conditions. This anomalous condition of ``enhanced transport'' represents a novel feature for flow in porous materials.Comment: 5 pages, 5 figures. This article appears also in Physical Review Letters 103 194502 (2009

Unveiling the bioactive potential of fresh fruit and vegetable waste in human health from a consumer perspective

Food supply disruption and shortage verified during the current pandemic events are a scenario that many anticipate for the near future. The impact of climate changes on food production, the continuous decrease in arable land, and the exponential growth of the human population are important drivers for this problem. In this context, adding value to food waste is an obvious strategy to mitigate food shortages, but there is a long way to go in this field. Globally, it is estimated that one-third of all food produced is lost. This is certainly due to many different factors, but the lack of awareness of the consumer about the nutritional value of certain foods parts, namely peels and seeds, is certainly among them. In this review, we will unveil the nutritional and bioactive value of the waste discarded from the most important fresh fruit and vegetables consumed worldwide as a strategy to decrease food waste. This will span the characterization of the bioactive composition of selected waste from fruits and vegetables, particularly their seeds and peels, and their possible uses, whether in our diet or recycled to other ends.info:eu-repo/semantics/publishedVersio

Neighborhood properties of complex networks

A concept of neighborhood in complex networks is addressed based on the criterion of the minimal number os steps to reach other vertices. This amounts to, starting from a given network $R_1$, generating a family of networks $R_\ell, \ell=2,3,...$ such that, the vertices that are $\ell$ steps apart in the original $R_1$, are only 1 step apart in $R_\ell$. The higher order networks are generated using Boolean operations among the adjacency matrices $M_\ell$ that represent $R_\ell$. The families originated by the well known linear and the Erd\"os-Renyi networks are found to be invariant, in the sense that the spectra of $M_\ell$ are the same, up to finite size effects. A further family originated from small world network is identified

Impact of urbanization trends on production of key staple crops

Urbanization has appropriated millions of hectares of cropland, and this trend will persist as cities continue to expand. We estimate the impact of this conversion as the amount of land needed elsewhere to give the same yield potential as determined by differences in climate and soil properties. Robust spatial upscaling techniques, well-validated crop simulation models, and soil, climate, and cropping system databases are employed with a focus on populous countries with high rates of land conversion. We find that converted cropland is 30–40% more productive than new cropland, which means that projection of food production potential must account for expected cropland loss to urbanization. Policies that protect existing farmland from urbanization would help relieve pressure on expansion of agriculture into natural ecosystems

Spatial frameworks for robust estimation of yield gaps

Food security interventions and policies need reliable estimates of crop production and the scope to enhance production on existing cropland. Here we assess the performance of two widely used ‘top-down’ gridded frameworks (Global Agro-ecological Zones and Agricultural Model Intercomparison and Improvement Project) versus an alternative ‘bottom-up’ approach (Global Yield Gap Atlas). The Global Yield Gap Atlas estimates extra production potential locally for a number of sites representing major breadbaskets and then upscales the results to larger spatial scales. We find that estimates from top-down frameworks are alarmingly unlikely, with estimated potential production being lower than current farm production at some locations. The consequences of using these coarse estimates to predict food security are illustrated by an example for sub-Saharan Africa, where using different approaches would lead to different prognoses about future cereal self-sufficiency. Our study shows that foresight about food security and associated agriculture research priority setting based on yield potential and yield gaps derived from top-down approaches are subject to a high degree of uncertainty and would benefit from incorporating estimates from bottom-up approaches