Gaussian superpositions in scalar-tensor quantum cosmological models

A free scalar field minimally coupled to gravity model is quantized and the Wheeler-DeWitt equation in minisuperspace is solved analytically, exhibiting positive and negative frequency modes. The analysis is performed for positive, negative and zero values of the curvature of the spatial section. Gaussian superpositions of the modes are constructed, and the quantum bohmian trajectories are determined in the framework of the Bohm-de Broglie interpretation of quantum cosmology. Oscillating universes appear in all cases, but with a characteristic scale of the order of the Planck scale. Bouncing regular solutions emerge for the flat curvature case. They contract classically from infinity until a minimum size, where quantum effects become important acting as repulsive forces avoiding the singularity and creating an inflationary phase, expanding afterwards to an infinite size, approaching the classical expansion as long as the scale factor increases. These are non-singular solutions which are viable models to describe the early Universe.Comment: 14 pages, LaTeX, 3 Postscript figures, uses graficx.st

Resposta da bananeira grand naine a diferentes concentrações da 2 agua de irrigão e frequencias de fertirrigação.

A banana é uma das frutas mais consumidas no mundo exigindo, dessa forma, manejo adequado para obtenção de produtividades satisfatórias aos produtores. Atualmente vem-se utilizando muito a fertirrigação (adubação via água de irrigação) devido suas vantagens como eficiência de aplicação dos nutrientes e menor mão-de-obra. Segundo Reichardt (1990) a lixiviação dos íons através do perfil do solo, é uma das principais causas de perdas de nutrientes, sendo consequência principalmente da alicação exagerada de água às plantas, o que indica a necessidade de adotar um manejo de água e nutrientes às culturas com bastante critério

The Consistency of Causal Quantum Geometrodynamics and Quantum Field Theory

We consider quantum geometrodynamics and parametrized quantum field theories in the framework of the Bohm-de Broglie interpretation. In the first case, and following the lines of our previous work [1], where a hamiltonian formalism for the bohmian trajectories was constructed, we show the consistency of the theory for any quantum potential, completing the scenarios for canonical quantum cosmology presented there. In the latter case, we prove the consistency of scalar field theory in Minkowski spacetime for any quantum potential, and we show, using this alternative hamiltonian method, a concrete example where Lorentz invariance of individual events is broken.Comment: Final version. See also http://www.cosmologia.cbpf.b

Can biological quantum networks solve NP-hard problems?

There is a widespread view that the human brain is so complex that it cannot be efficiently simulated by universal Turing machines. During the last decades the question has therefore been raised whether we need to consider quantum effects to explain the imagined cognitive power of a conscious mind. This paper presents a personal view of several fields of philosophy and computational neurobiology in an attempt to suggest a realistic picture of how the brain might work as a basis for perception, consciousness and cognition. The purpose is to be able to identify and evaluate instances where quantum effects might play a significant role in cognitive processes. Not surprisingly, the conclusion is that quantum-enhanced cognition and intelligence are very unlikely to be found in biological brains. Quantum effects may certainly influence the functionality of various components and signalling pathways at the molecular level in the brain network, like ion ports, synapses, sensors, and enzymes. This might evidently influence the functionality of some nodes and perhaps even the overall intelligence of the brain network, but hardly give it any dramatically enhanced functionality. So, the conclusion is that biological quantum networks can only approximately solve small instances of NP-hard problems. On the other hand, artificial intelligence and machine learning implemented in complex dynamical systems based on genuine quantum networks can certainly be expected to show enhanced performance and quantum advantage compared with classical networks. Nevertheless, even quantum networks can only be expected to efficiently solve NP-hard problems approximately. In the end it is a question of precision - Nature is approximate.Comment: 38 page

Caracterização da fertilidade dos solos do distrito de irrigação platôs de Guadalupe, Piauí.

O presente trabalho teve por objetivo avaliar as características químicas presentes nos solos do Distrito de Irrigação Platôs de Guadalupe, Guadalupe, PI, com o intuito de identificar a necessidade de adubação e calagem nos solos das áreas amostradas. As amostras de solo foram coletadas em dezoito lotes, nas camadas de 0-20 e 20-40 cm, totalizando 36 amostras. As características analisadas foram: matéria orgânica, pH, fósforo, potássio, cálcio, magnésio, acidez trocável, acidez potencial, capacidade de troca de cátions e saturação por bases. É necessária a execução de um programa de correção e adubação do solo para que as culturas expressem o seu potencial produtivo, de modo a não comprometer a resposta das plantas ao adequado fornecimento de água

Ecological methods and indicators for recovering and monitoring ecosystems after mining: A global literature review.

Mining contributes significantly to the world's economy. However, it brings strong environmental impacts, including the destruction of the original vegetation. In this way, the recovery of degraded areas by mining has been a mandatory procedure in many countries. With the objective to review this subject, a bibliometric analysis was carried out using scientific articles published in the period 1990?2018. A total of 700 articles in 171 journals were sampled. Ecological Engineering and Restoration Ecology were the journals with the largest number of articles. There was a significant increase of articles along time approaching the use of geotechnologies and arbuscular fungi. Recovered or recovering ecosystems were studied in 45 countries, mainly in Brazil, Australia, USA, China, and Spain. Coal and bauxite were the most common resources mined. The most frequent recovery methods were: seedling planting, direct seeding, natural regeneration, and hydroseeding, with techniques employed in some of them. In 35.71% of the articles, a small number of species (2?5) were used for the initial plant's establishment. The number of articles decreased as the number of both, plant species used in the initial recovery phase, and ecosystem's age increased. In monitoring, the most important indicators were classified as functional or functional plus structural. From the functional indicators, the Technosols or rebuilt soils were the most evaluated. Future perspectives on forests recovery includes methods tailored to peculiar features (soil and economic) of each ecosystem. For the forest recovery monitoring, the use of geotechnologies, mainly the Unmanned Aerial Vehicles (UAVs), as well as wildlife indicators tend to increase rapidly

Competitividade do leite em pó integral brasileiro.

Entre os produtos lácteos exportados pelo Brasil, o leite em pó é um dos mais importantes para a balança comercial brasileira, em especial o leite em pó integral. Apesar de ter sido considerado um grande importador de leite em pó na década de 1990, em 2008 o Brasil exportou cerca de 82 mil toneladas do produto, ou 377 milhões de dólares, tendo ocupado a oitava posição no ranking mundial de exportação do produto. No entanto, as exportações brasileiras do produto caíram novamente a partir de 2009, como efeito da crise mundial. Diante disso, torna-se oportuno avaliar a competitividade do Brasil no comércio mundial de leite em pó integral, como forma de identificar se o País tem potencial exportador. Para tal, foram utilizados dois índices: a Vantagem Comparativa revelada e a Posição Relativa de Mercado. Foram comparados sete países: Brasil, Argentina, Nova Zelândia, Estados Unidos, Holanda, Austrália e Bélgica. Os resultados mostraram grande vantagem comparativa para a Nova Zelândia. Os demais países mostraram possibilidades de crescimento, inclusive o Brasil, mas para isso algumas medidas voltadas para o posicionamento competitivo no mercado lácteo mundial devem ser tomada