Dimensionless cosmology

Although it is well known that any consideration of the variations of fundamental constants should be restricted to their dimensionless combinations, the literature on variations of the gravitational constant $G$ is entirely dimensionful. To illustrate applications of this to cosmology, we explicitly give a dimensionless version of the parameters of the standard cosmological model, and describe the physics of Big Bang Neucleosynthesis and recombination in a dimensionless manner. The issue that appears to have been missed in many studies is that in cosmology the strength of gravity is bound up in the cosmological equations, and the epoch at which we live is a crucial part of the model. We argue that it is useful to consider the hypothetical situation of communicating with another civilization (with entirely different units), comparing only dimensionless constants, in order to decide if we live in a Universe governed by precisely the same physical laws. In this thought experiment, we would also have to compare epochs, which can be defined by giving the value of any {\it one} of the evolving cosmological parameters. By setting things up carefully in this way one can avoid inconsistent results when considering variable constants, caused by effectively fixing more than one parameter today. We show examples of this effect by considering microwave background anisotropies, being careful to maintain dimensionlessness throughout. We present Fisher matrix calculations to estimate how well the fine structure constants for electromagnetism and gravity can be determined with future microwave background experiments. We highlight how one can be misled by simply adding $G$ to the usual cosmological parameter set

Spatial, Temporal, and Hybrid Decompositions for Large-Scale Vehicle Routing with Time Windows

This paper studies the use of decomposition techniques to quickly find high-quality solutions to large-scale vehicle routing problems with time windows. It considers an adaptive decomposition scheme which iteratively decouples a routing problem based on the current solution. Earlier work considered vehicle-based decompositions that partitions the vehicles across the subproblems. The subproblems can then be optimized independently and merged easily. This paper argues that vehicle-based decompositions, although very effective on various problem classes also have limitations. In particular, they do not accommodate temporal decompositions and may produce spatial decompositions that are not focused enough. This paper then proposes customer-based decompositions which generalize vehicle-based decouplings and allows for focused spatial and temporal decompositions. Experimental results on class R2 of the extended Solomon benchmarks demonstrates the benefits of the customer-based adaptive decomposition scheme and its spatial, temporal, and hybrid instantiations. In particular, they show that customer-based decompositions bring significant benefits over large neighborhood search in contrast to vehicle-based decompositions

A time-based pheromone approach for the ant system

The ant system (AS) is a metaheuristic approach originally developed for solving the traveling salesman problem. AS has been successfully applied to various hard combinatorial optimization problems and different variants have been proposed in the literature. In this paper, we introduce a time-based pheromone approach for AS (TbAS). Due to this nature TbAS is applicable to routing problems involving time-windows. The novelty in TbAS is the multi-layer pheromone network structure which implicitly utilizes the service time information associated with the customers as a heuristic information. To investigate the performance of TbAS, we use the well-known vehicle routing problem with time-windows as our testbed and we conduct an extensive computational study using the Solomon [29] instances. Our results reveal that the proposed time-based pheromone approach is effective in obtaining good quality solutions

Sistemas de integração lavoura-pecuária na região do Cerrado

O objetivo deste trabalho foi analisar os benefícios e as perspectivas potenciais de sistemas de integração lavoura-pecuária no processo de intensificação de uso das áreas em exploração com lavoura de grãos e pastagens no Cerrado, e apontar as principais lacunas de informação sobre o sistema. Os principais benefícios da integração lavoura-pecuária são: melhoria das propriedades químicas, físicas e biológicas do solo; redução da ocorrência de doenças, insetos-pragas e plantas daninhas; maior produtividade das plantas e dos animais; e redução de riscos pela diversificação de atividades. No entanto, a adoção do sistema de integração lavoura-pecuária ainda é pequena, provavelmente em virtude da maior complexidade desse sistema. Concentrar esforços nos fatores que limitam a adoção desse sistema no Cerrado parece ser um ponto estratégico para novos estudos. A busca por melhoria na qualidade de cobertura de solo para o sistema plantio direto, por meio de gramíneas forrageiras, pode auxiliar na adoção da integração lavoura-pecuária no Cerrado. A expectativa é de que a adoção de sistemas de integração lavoura-pecuária resulte em melhorias significativas na sustentabilidade socioeconômica e ambiental das propriedades e da sua região de influência

Reproductive biology of Steindachnerina insculpta (Fernandez-Yépez) (Teleostei, Curimatidae) in Furnas reservoir, Minas Gerais, Brazil Biologia reprodutiva de Steindachnerina insculpta (Fernandez-Yépez) (Teleostei, Curimatidae) no reservatório de Furnas, Minas Gerais, Brasil

The 'saguiru' Steindachnerina insculpta, a small teleost detritivorous fish species in Furnas reservoir, upper rio Paraná basin, Minas Gerais, Brazil, has a prolonged period of reproductive activity that extends from September to March, with fractionated spawning. During gonadal maturation, the females showed a low hepatosomatic index, suggesting that hepatic substances are possibly transferred from liver to ovaries. During the reproductive period, this fish had lower stomach repletion and coelomic fat indexes, indicating that the species eat less and consume more fat reserves. The weight of the ovaries influenced positively the condition factor (K1), since the lowest K2 values (without the gonads weight), were obtained during maturation, confirming the influence of the weight of the ovaries upon the physiological condition of the females.<br>O 'saguiru' Steindachnerina insculpta, peixe teleósteo detritívoro que ocorre no reservatório de Furnas, bacia do alto Paraná, Minas Gerais, apresenta período reprodutivo prolongado que se estende de setembro a março, com desova parcelada. Durante a maturação gonadal, fêmeas apresentaram baixos valores do índice hepatossomático, sugerindo que possivelmente, substâncias hepáticas são transferidas do fígado para os ovários. Durante o período reprodutivo, os peixes desta espécie apresentam índices de repleção estomacal e de gordura celômica baixos, indicando diminuição da atividade alimentar e consumo de reservas. O peso dos ovários influencia positivamente o fator de condição (K1), uma vez que os mais baixos valores de K2 (sem o peso das gônadas) foram obtidos durante a maturação, confirmando a influência do peso dos ovários na condição fisiológica das fêmeas