9,661 research outputs found
The first analytical expression to estimate photometric redshifts suggested by a machine
We report the first analytical expression purely constructed by a machine to
determine photometric redshifts () of galaxies. A simple and
reliable functional form is derived using galaxies from the Sloan
Digital Sky Survey Data Release 10 (SDSS-DR10) spectroscopic sample. The method
automatically dropped the and bands, relying only on , and
for the final solution. Applying this expression to other SDSS-DR10
galaxies, with measured spectroscopic redshifts (), we achieved a
mean and a scatter when averaged up to . The method was
also applied to the PHAT0 dataset, confirming the competitiveness of our
results when faced with other methods from the literature. This is the first
use of symbolic regression in cosmology, representing a leap forward in
astronomy-data-mining connection.Comment: 6 pages, 4 figures. Accepted for publication in MNRAS Letter
Using gamma regression for photometric redshifts of survey galaxies
Machine learning techniques offer a plethora of opportunities in tackling big
data within the astronomical community. We present the set of Generalized
Linear Models as a fast alternative for determining photometric redshifts of
galaxies, a set of tools not commonly applied within astronomy, despite being
widely used in other professions. With this technique, we achieve catastrophic
outlier rates of the order of ~1%, that can be achieved in a matter of seconds
on large datasets of size ~1,000,000. To make these techniques easily
accessible to the astronomical community, we developed a set of libraries and
tools that are publicly available.Comment: Refereed Proceeding of "The Universe of Digital Sky Surveys"
conference held at the INAF - Observatory of Capodimonte, Naples, on
25th-28th November 2014, to be published in the Astrophysics and Space
Science Proceedings, edited by Longo, Napolitano, Marconi, Paolillo, Iodice,
6 pages, and 1 figur
Eletroforese de isoenzimas de plântulas na identificação de espécies de Brachiaria.
Lotes de sementes de braquiaria comercializados no Brasil vem apresentando contaminacoes som sementes de outras especies pertencentes ao mesmo genero. Deste modo, uma das especies de braquiaria atuaria como planta infestante da outra no agroecossistema e a erradicacao da especie infestante seria dificultada pela agressividade caracteristca do genero e pela falta de seletividade dos herbecidas disponiveis no mercado
A extinção da punibilidade dos crimes tributários pelo pagamento e a sonegação
O trabalho tem por objeto a análise do regime brasileiro de extinção da punibilidade dos crimes contra a ordem tributária pelo pagamento do tributo. O objetivo inicial é compreender os crimes tributários de forma geral, bem como as motivações dos agentes que cometem esses crimes, para, em seguida, analisar a extinção de punibilidade pelo pagamento do tributo a qualquer momento e a consequência disso no que se refere à sonegação fiscal. Na sequência, o regime de extinção da punibilidade brasileiro será cotejado com o regime de outros países e ao final, o trabalho buscará demonstrar que o atual sistema brasileiro de extinção de punibilidade pelo pagamento incentiva a sonegação fiscal e deve ser reformulado
Growth of Urochloa grass in an oxisol treated with powdered silicate materials.
An experiment was carried out in pots with a soil mixed with six powdered silicate materials originated from mining (kyanite, biotite schist, biotite syenite, basalt, vermiculite, or bentonite). These sources were mixed in 4.4 kg of soil (Anionic Acrustox) at the rates of 0 (control), or 440 g of ground silicate materials, in pots where Urochloa decumbens cultivar Basilisk was grown. The grass growth followed the relative total dry mass (%): 100 > 93.8 > 82.7 > 71.4 > 54.4 > 9.4 > 6.8 for biotite schist, bentonite, vermiculite, basalt, syenite, kyanite, and soil (control), respectively. Soil pH (6.5) ultimately decreased Mn availability to plants. Although some silicate materials increased Mn availability to plants, increasing treated plants growth, it was not possible to evaluate if plants were able to acquire more P when treated with silicate materials. Concentrations of Fe and P extracted from the soil and from shoots were highly correlated with dry mass. The reactivity of these materials in soils increasing soil pH may be an important parameter for ranking agrominerals, as the availability of nutrients was correlated to the amount of carbonate used to increase pH of the treated soil to 6.5.Título em português: Crescimento de capim Urochloa em um latossolo tratado com materiais silicáticos em pó
Crescimento em diâmetro de castanha-do-brasil (Bertholletia excelsa H.B.K.) cultivada em solo de baixa fertilidade.
O presente trabalho foi realizado com a finalidade de estimar curvas de crescimento em diâmetro de Bertholletia excelsa H.B.K. em condições de plantio solteiro e consorciado em solo de baixa fertilidade no Estado de Rondônia.bitstream/item/24773/1/ct79-castanhadobrasil.pd
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