Automated data pre-processing via meta-learning

The final publication is available at link.springer.comA data mining algorithm may perform differently on datasets with different characteristics, e.g., it might perform better on a dataset with continuous attributes rather than with categorical attributes, or the other way around. As a matter of fact, a dataset usually needs to be pre-processed. Taking into account all the possible pre-processing operators, there exists a staggeringly large number of alternatives and nonexperienced users become overwhelmed. We show that this problem can be addressed by an automated approach, leveraging ideas from metalearning. Specifically, we consider a wide range of data pre-processing techniques and a set of data mining algorithms. For each data mining algorithm and selected dataset, we are able to predict the transformations that improve the result of the algorithm on the respective dataset. Our approach will help non-expert users to more effectively identify the transformations appropriate to their applications, and hence to achieve improved results.Peer ReviewedPostprint (published version

Adaptabilidade de linhagens e cultivares de feijao (Phaseolus vulgaris L.) em Rondonia e resistencia a "mela" (Thanatephorus cucumeris (Frank.) Donk).

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Transition to turbulence in particulate pipe flow

We investigate experimentally the influence of suspended particles on the transition to turbulence. The particles are monodisperse and neutrally-buoyant with the liquid. The role of the particles on the transition depends both upon the pipe to particle diameter ratios and the concentration. For large pipe-to-particle diameter ratios the transition is delayed while it is lowered for small ratios. A scaling is proposed to collapse the departure from the critical Reynolds number for pure fluid as a function of concentration into a single master curve.Comment: 4 pages, 4 figure

Uso de misturas de sementes no cultivo de feijão.

Mostra a produtividade de três linhagens de feijão, em monocultura, das cultivares Costa Rica, Preto G1 e Preto EEP 551, para capacidade de competição no plantio das águas de 1980. A boa distribuição das chuvas durante o ciclo da cultura contribuiu para a obtenção de elevadas produtividades.bitstream/item/26057/1/comt-12.pd

Economic and agronomic evaluation of a common bean experiment Uberaba, Minas Gerais

Com a finalidade de estudar as possibilidades de aproveitamento dos cerrados da região para o cultivo do feijão, foi analisada a influência, na produção, de cinco níveis de N e P2O5 utilizando-se um fatorial 5X5 completo. A partir dêsse esquema experimental comparou-se a eficiência de quatro outros delineamentos. Um esquema central composto mais os extremos teve eficiência equivalente ao do fatorial 5x5 completo e foi utilizado na interpretação econômica. Determinou-se a superfície da resposta dos insumos e produção e as combinações de nutrientes que resultaram nos lucros máximos. Finalmente, na última parte do trabalho foram feitas considerações sobre procedimentos alternativos do uso dos insumos face a variações dos preços do produto dos insumos.An economic and agronomic evaluation of the possibilities to produce common beans in poor "cerrado" in central Brazil was made by the use of five levels of N and P2O5. The experimental portion of the paper deals with a comparison of several types of "treatment designs", some of which are specific for estimating response surfaces. The results from one of the latter designs were used to demonstrate the general principles of agronomic economics analysis. .The results have shown that central composite plus extremes design provided information equivalent to the standard 5x5 factorial with the use of fewer resources and, therefore, was used in the economic phase of the paper. The other designs studied were small and large 3x3 factorials and central composite. To evaluate the use of N and P2O5 in the production of beans, estimates were made of the economically relevant portions of the plant nutrient input-output surface. A graphic illustration of three curves of a family of isoquants for the production of beans was made. Points of equal marginal rate or substitution of successively higher isoquants were marked by the line called isocline. Output maximization and cost minimization were determined as well as profit maximization. The return per hectare after deducting costs of applied N and P2O5 vary with the price of beans per kg. In general, optimal quantities of inputs and residual return fall as factor prices increase. However, a greater percentage of decrease occurs in residual return per hectare and in yield per hectare, as the price of P2O5 increases (with the price of N held constant). It was shown that the proper anticipation of the price of beans is important to the farmer to obtain maximum returns. He will use the most profitable combination of inputs

Active and driven hydrodynamic crystals

Motivated by the experimental ability to produce monodisperse particles in microfluidic devices, we study theoretically the hydrodynamic stability of driven and active crystals. We first recall the theoretical tools allowing to quantify the dynamics of elongated particles in a confined fluid. In this regime hydrodynamic interactions between particles arise from a superposition of potential dipolar singularities. We exploit this feature to derive the equations of motion for the particle positions and orientations. After showing that all five planar Bravais lattices are stationary solutions of the equations of motion, we consider separately the case where the particles are passively driven by an external force, and the situation where they are self-propelling. We first demonstrate that phonon modes propagate in driven crystals, which are always marginally stable. The spatial structure of the eigenmodes depend solely on the symmetries of the lattices, and on the orientation of the driving force. For active crystals, the stability of the particle positions and orientations depends not only on the symmetry of the crystals but also on the perturbation wavelengths and on the crystal density. Unlike unconfined fluids, the stability of active crystals is independent of the nature of the propulsion mechanism at the single particle level. The square and rectangular lattices are found to be linearly unstable at short wavelengths provided the volume fraction of the crystals is high enough. Differently, hexagonal, oblique, and face-centered crystals are always unstable. Our work provides a theoretical basis for future experimental work on flowing microfluidic crystals.Comment: 10 pages, 10 figure

Electrostatic Control of the Thermoelectric Figure of Merit in Ion-Gated Nanotransistors

Semiconductor nanostructures have raised much hope for the implementation of high-performance thermoelectric generators. Indeed, they are expected to make available reduced thermal conductivity without a heavy trade-off on electrical conductivity, a key requirement to optimize the thermoelectric figure of merit. Here, a novel nanodevice architecture is presented in which ionic liquids are employed as thermally-insulating gate dielectrics. These devices allow the field-effect control of electrical transport in suspended semiconducting nanowires in which thermal conductivity can be simultaneously measured using an all-electrical setup. The resulting experimental data on electrical and thermal transport properties taken on individual nanodevices can be combined to extract ZT, guide device optimization and dynamical tuning of the thermoelectric properties

Augmented muscle vasodilatory responses in obese children with Glu27 beta(2)-adrenoceptor polymorphism

This study examined forearm vasodilatation during mental challenge and exercise in 72 obese children (OC; age = 10 +/- 0.1 years) homozygous with polymorphism in the allele 27 of the beta(2)-adrenoceptors: Gln27 (n = 61) and Glu27 (n = 11). Forearm blood flow was recorded during 3 min of each using the Stroop color-word test (MS) and handgrip isometric exercise. Baseline hemodynamic and vascular measurements were similar. During the MS, peak forearm vascular conductance was significantly greater in group Glu27 (Delta = 0.35 +/- 0.4 vs. 0.12 +/- 0.1 units, respectively, p = .042). Similar results were found during exercise (Delta = 0.64 +/- 0.1 vs. 0.13 +/- 0.1 units, respectively, p = .035). Glu27 OC increased muscle vasodilatory responsiveness upon the MS and exercise

Complex Fluids and Hydraulic Fracturing

Nearly 70 years old, hydraulic fracturing is a core technique for stimulating hydrocarbon production in a majority of oil and gas reservoirs. Complex fluids are implemented in nearly every step of the fracturing process, most significantly to generate and sustain fractures and transport and distribute proppant particles during and following fluid injection. An extremely wide range of complex fluids are used: naturally occurring polysaccharide and synthetic polymer solutions, aqueous physical and chemical gels, organic gels, micellar surfactant solutions, emulsions, and foams. These fluids are loaded over a wide range of concentrations with particles of varying sizes and aspect ratios and are subjected to extreme mechanical and environmental conditions. We describe the settings of hydraulic fracturing (framed by geology), fracturing mechanics and physics, and the critical role that non-Newtonian fluid dynamics and complex fluids play in the hydraulic fracturing process