Linear Invariant Systems Theory for Signal Enhancement

This paper discusses a linear time invariant (LTI) systems approach to signal enhancement via projective subspace techniques. It provides closed form expressions for the frequency response of data adaptive finite impulse response eigenfilters. An illustrative example using speech enhancement is also presented.Este artigo apresenta a aplicação da teoria de sistemas lineares invariantes no tempo (LTI) na análise de técnicas de sub-espaço. A resposta em frequência dos filtros resultantes da decomposição em valores singulares é obtida aplicando as propriedades dos sistemas LTI

How to predict soil water holding capacity using physically based equations?

The soil surface and porosity govern the capacity of soil to hold water. In soil science, many functions were developed to estimate parameters of equations to describe soil water retention and soil hydraulic properties. These functions were created using statistical techniques based in soil properties parameters less laborious and cheaply obtained than the direct measurements of soil hydraulic parameters. These functions are called pedotransfer functions (PTF) and fill the gap between the available soil data and the properties required for modeling soil water fluxes. The physically based equations approach to obtain functions of water retention and hydraulic conductivity of the porous media (soils) may be advantageous, as the predictors will not be select by statistical procedures and be strongly influenced by the available data base and technique used, moreover the predictors will have also a physical meaning. Examples of physically based equations to predict soil water content in function of dielectric conductivity in soils is given and the demand of physically based equation to predict soil water hold capacity and soil hydraulic conductivity is addressed

Performance of dynamical decoupling in bosonic environments and under pulse-timing fluctuations

We study the suppression of qubit dephasing through Uhrig dynamical decoupling (UDD) in nontrivial environments modeled within the spin-boson formalism. In particular, we address the case of (i) a qubit coupled to a bosonic bath with power-law spectral density, and (ii) a qubit coupled to a single harmonic oscillator that dissipates energy into a bosonic bath, which embodies an example of a structured bath for the qubit. We then model the influence of random time jitter in the UDD protocol by sorting pulse-application times from Gaussian distributions centered at appropriate values dictated by the optimal protocol. In case (i) we find that, when few pulses are applied and a sharp cutoff is considered, longer coherence times and robust UDD performances (against random timing errors) are achieved for a super-Ohmic bath. On the other hand, when an exponential cutoff is considered a super-Ohmic bath is undesirable. In case (ii) the best scenario is obtained for an overdamped harmonic motion. Our study provides relevant information for the implementation of optimized schemes for the protection of quantum states from decoherence.Comment: 8 pages, 5 figure

Mirror-assisted coherent backscattering from the Mollow sidebands

In front of a mirror, the radiation of weakly driven large disordered clouds presents an interference fringe in the backward direction, on top of an incoherent background. Although strongly driven atoms usually present little coherent scattering, we here show that the mirror-assisted version can produce high contrast fringes, for arbitrarily high saturation parameters. The contrast of the fringes oscillates with the Rabi frequency of the atomic transition and the distance between the mirror and the atoms, due to the coherent interference between the carrier and the Mollow sidebands of the saturated resonant fluorescence spectrum emitted by the atoms. The setup thus represents a powerful platform to study the spectral properties of ensembles of correlated scatterers

O manejo do solo pelas populações pré-colombianas na Amazônia brasileira: vestígios deixados nas terras pretas de índio e terras mulatas.

Práticas agrícolas na época pré-colombiana. As terras pretas de índio (TPI). Evidências do uso do fogo nas práticas agrícolas. As terras mulatas

Creation of fertile soil horizons (anthrosols) in the pre colombian times by using organic wastes.

The process of formation and evolution of distinct anthropic horizons found widespread in Brazil will be reviewed and discussed focusing in the waste management. The Amazonian Dark Earths (Terra Preta de Índio), the shell mounds (sambaquis) and ditches from human earthworks (called geoglifos) are the archeological sites reviewed in this article. The main source of P and Ca in TPI sites is believed to be from the bones. Ashes are also a key source of nutrients in antropic soils and responsible to enhance the pH. Leaves are also a important source of nutrient. TPI owes its name to the dark color originated from a large stocks of carbon and it is believed that large part is preserved because a pyrogenic origin. The use of carbonized organic waste (charcoal) as soil conditioner is now being largely studied in the world, this technology is called biochar. The sambaquis are found mainly along the Brazilian coast with have a large amount of phosphorus and carbon. The geoglifos are constructed earthworks mainly circular or rectangular. Until now is intriguing the absence of dark horizons or clearly chemical signatures typical of anthropic modifications caused by waste accumulation in or near the geoglifos. Understanding the waste management used to create these fertile anthropic soils have possibility to provide new soil management practices for soil reclamation, sustainable production, and to enhance soil carbon storage and nutrient holding capacity therefore to use marginal soils

Land use effects on soil physical and hydraulic properties of a clayey ferralsol in the Central Amazon.

The land use systems in the central amazon. Soil quality and sustainable land use systems. Climate. Geology and the clayey ferralsol. Vegetation. Land use, experiment design and management. Management of the experimental plots. Land use effects on soil physical properties. Agroforestry system. Monoculture of cupuacu. Primary and secondary forest. Land use effects on total porosity and size distribution.Tese (Doctor Sc. Thesis) - Universitat Bayreuth, Bayreuth