Experimental Realization of the Fuse Model of Crack Formation

In this work, we present an experimental investigation of the fuse model. Our main goal was to study the influence of the disorder on the fracture process. The experimental apparatus used consisted of an $L\times L$ square lattice with fuses placed on each bond of the lattice. Two types of materials were used as fuses: copper and steel wool wires. The lattice composed only by copper wires varied from a weakly disordered system to a strongly disordered one. The lattice formed only by steel wool wires corresponded to a strongly disordered one. The experimental procedure consisted of applying a potential difference V to the lattice and measuring the respective current I. The characteristic function $I(V)$ obtained was investigated in order to find the scaling law dependence of the voltage and the current on the system size $L$ when the disorder was changed. Our results show that the scaling laws are only verified for the disordered regime.Comment: 4 pages, 8 figures.ep

Microscopic mechanism for mechanical polishing of diamond (110) surfaces

Mechanically induced degradation of diamond, as occurs during polishing, is studied using total--energy pseudopotential calculations. The strong asymmetry in the rate of polishing between different directions on the diamond (110) surface is explained in terms of an atomistic mechanism for nano--groove formation. The post--polishing surface morphology and the nature of the polishing residue predicted by this mechanism are consistent with experimental evidence.Comment: 4 pages, 5 figure

Metagenomic sequencing unravels gene fragments with phylogenetic signatures of O2-tolerant NiFe membrane-bound hydrogenases in lacustrine sediment

Many promising hydrogen technologies utilising hydrogenase enzymes have been slowed by the fact that most hydrogenases are extremely sensitive to O2. Within the group 1 membrane-bound NiFe hydrogenase, naturally occurring tolerant enzymes do exist, and O2 tolerance has been largely attributed to changes in iron–sulphur clusters coordinated by different numbers of cysteine residues in the enzyme’s small subunit. Indeed, previous work has provided a robust phylogenetic signature of O2 tolerance [1], which when combined with new sequencing technologies makes bio prospecting in nature a far more viable endeavour. However, making sense of such a vast diversity is still challenging and could be simplified if known species with O2-tolerant enzymes were annotated with information on metabolism and natural environments. Here, we utilised a bioinformatics approach to compare O2-tolerant and sensitive membrane-bound NiFe hydrogenases from 177 bacterial species with fully sequenced genomes for differences in their taxonomy, O2 requirements, and natural environment. Following this, we interrogated a metagenome from lacustrine surface sediment for novel hydrogenases via high-throughput shotgun DNA sequencing using the Illumina™ MiSeq platform. We found 44 new NiFe group 1 membrane-bound hydrogenase sequence fragments, five of which segregated with the tolerant group on the phylogenetic tree of the enzyme’s small subunit, and four with the large subunit, indicating de novo O2-tolerant protein sequences that could help engineer more efficient hydrogenases

Ganho de peso bovino em resteva de arroz irrigado na safra de 2009/2010 na Embrapa Pecuária Sul.

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Citations, funding and influence in Energy-Policy research on Developing Economies

Energy research seeking to influence policy in low- and -middle-income countries (LMICs) is often funded by – and conceptualised by authors in - institutions from high-income countries (HICs). Research agendas and policy recommendations determined in HICs potentially yield the most influence on policymaking for LMICs. This leaves a multidimensional gap in how LMICs frame, contextualise, evidence and enact policy processes. The unique contribution of this paper is analysing the dynamics of prevalent energy research on LMICs through a multi-method approach using bibliometric, network science and regression-based techniques. An innovative data-driven framework was established using a sample of 6,636 papers from the Web of Science database, combined with journal impact data from Scimago Journal Ranking and country economic data from the World Bank. Results show the existence of a cycle of imbalances across research practices. Most papers recommending energy policy for LMICs have a first author based in a HIC, funded by a HIC institution. Total citations of articles on energy policy in LMICs increase with the GDP of the first author’s country (a 1% increase in GDP is correlated with a 0.68% increase in total citations). Funders support authors based in countries of the same income band as them, or higher. Therefore, we recommend revising research practices and HIC funding policies to place local actors and knowledge at the heart of energy policy research, enabling high-impact policymaking in LMICs

What Physical Education Teachers Know About Asthma: Impact of a Training Course

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Avaliação de crescimento inicial de mudas de Amoreira-preta.

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Analysis of the economic viability from an integrated system of rice and beef cattle in the Pampa Biome of Rio Grande do Sul.

The environmental conditions of the Pampa Biome are favorable to the degradation of soil, especially when grain crops are introduced in this region, traditionally exploited with beef cattle systems

Raising Brangus steers on natural pasture developed after irrigated rice crop in the Pampa biome of Rio Grande do Sul state, Brazil.

The traditional systems of exploitation with beef cattle in the Pampa biome of Rio Grande do Sul presents historically low rates of productivity and profitability due, mainly, to the inadequate management of natural pastures