Crescimento inicial de mudas de Euterpe precatoria em função da adubação nitrogenada.

O açaizeiro é uma cultura que ganhou mercado nos últimos anos devido à importância pela qualidade nutricional da polpa dos frutos. O plantio de mudas de qualidade é fundamental para o estabelecimento no campo e para isso precisa ser conduzida adequadamente no viveiro realizando-se os tratos culturais recomendados. O objetivo deste estudo foi avaliar o crescimento inicial de mudas de açaizeiro em função de adubação nitrogenada. O experimento foi conduzido no viveiro da Embrapa Acre, em Rio Branco, AC.Organizado por: Henrique Nery Cipriani; Alaerto Luiz Marcolan; Fernando Machado Pfeifer: Alexandre Martins Abdão dos Passos; Marcelo Curitiba Espíndula; Angelo Mansur Mendes

Photon-Counting Spectral Phase-Contrast Mammography

Phase-contrast imaging is an emerging technology that may increase the signal-difference-to-noise ratio in medical imaging. One of the most promising phase-contrast techniques is Talbot interferometry, which, combined with energy-sensitive photon-counting detectors, enables spectral differential phase-contrast mammography. We have evaluated a realistic system based on this technique by cascaded-systems analysis and with a task-dependent ideal-observer detectability index as a figure-of-merit. Beam-propagation simulations were used for validation and illustration of the analytical framework. Differential phase contrast improved detectability compared to absorption contrast, in particular for fine tumor structures. This result was supported by images of human mastectomy samples that were acquired with a conventional detector. The optimal incident energy was higher in differential phase contrast than in absorption contrast when disregarding the setup design energy. Further, optimal weighting of the transmitted spectrum was found to have a weaker energy dependence than for absorption contrast. Taking the design energy into account yielded a superimposed maximum on both detectability as a function of incident energy, and on optimal weighting. Spectral material decomposition was not facilitated by phase contrast, but phase information may be used instead of spectral information.QC 20120731</p