The many faces of LINER-like galaxies: a WISE view

We use the SDSS and WISE surveys to investigate the real nature of galaxies defined as LINERs in the BPT diagram. After establishing a mid-infrared colour W2-W3 = 2.5 as the optimal separator between galaxies with and without star formation, we investigate the loci of different galaxy classes in the W_{Ha} versus W2-W3 space. We find that: (1) A large fraction of LINER-like galaxies are emission-line retired galaxies, i.e galaxies which have stopped forming stars and are powered by hot low-mass evolved stars (HOLMES). Their W2-W3 colours show no sign of star formation and their Ha equivalent widths, W_{Ha}, are consistent with ionization by their old stellar populations. (2) Another important fraction have W2-W3 indicative of star formation. This includes objects located in the supposedly `pure AGN' zone of the BPT diagram. (3) A smaller fraction of LINER-like galaxies have no trace of star formation from W2-W3 and a high W_{Ha}, pointing to the presence of an AGN. (4) Finally, a few LINERs tagged as retired by their W_{Ha} but with W2-W3 values indicative of star formation are late-type galaxies whose SDSS spectra cover only the old `retired' bulge. This reinforces the view that LINER-like galaxies are a mixed bag of objects involving different physical phenomena and observational effects thrusted into the same locus of the BPT diagram.Comment: Accepted for publication in MNRAS; 9 pages, 6 figure

Viroses da batata-doce no Brasil: importância e principais medidas de controle.

bitstream/item/84771/1/ct-126.pd

Viroses do alho no Brasil: importância e principais medidas de controle

bitstream/item/84849/1/ct-122.pd

Aspectos citológicos e bioquímicos da interação entre Mycosphaerella fijiensis e Musa sp.

A bananeira é cultivada em todas as regiões tropicais do mundo, sendo a banana a fruta de maior produção e comercialização mundial. Entretanto, a cultura da banana enfrenta o ataque de diversos patógenos que contribuem para redução de sua produtividade, notadamente a sigatoka negra, causada pelo fungo Mycosphaerella fijiensis Morelet, estádio anamórfico Paracercospora fijiensis (Morelet) Deighton. Apresentando ampla distribuição geográfica, a sigatoka negra causa a morte precoce das folhas infectadas sendo responsável por perdas superiores a 50% da produção. Para se defenderem de doenças e pragas, as plantas estão equipadas com as defesas constitutivas, naturalmente presentes na planta, funcionando como barreiras físicas, tais como a cutícula e os tricomas, e barreiras químicas, incluindo os inibidores de proteases, fenóis, PR-Proteínas e enzimas do estresse oxidativo, e as defesas induzidas. Este trabalho relata as avaliações citológicas e bioquímicas decorrentes da interação entre o fungo M. fijiensis e Musa sp., demonstrando os índices de germinação e penetração de esporos e os níveis de atividades de enzimas ligadas ao mecanismo de defesa da bananeira

Neural network applications in polymerization processes

Neural networks currently play a major role in the modeling, control and optimization of polymerization processes and in polymer resin development. This paper is a brief tutorial on simple and practical procedures that can help in selecting and training neural networks and addresses complex cases where the application of neural networks has been successful in the field of polymerization.401418Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Recording from two neurons: second order stimulus reconstruction from spike trains and population coding

We study the reconstruction of visual stimuli from spike trains, recording simultaneously from the two H1 neurons located in the lobula plate of the fly Chrysomya megacephala. The fly views two types of stimuli, corresponding to rotational and translational displacements. If the reconstructed stimulus is to be represented by a Volterra series and correlations between spikes are to be taken into account, first order expansions are insufficient and we have to go to second order, at least. In this case higher order correlation functions have to be manipulated, whose size may become prohibitively large. We therefore develop a Gaussian-like representation for fourth order correlation functions, which works exceedingly well in the case of the fly. The reconstructions using this Gaussian-like representation are very similar to the reconstructions using the experimental correlation functions. The overall contribution to rotational stimulus reconstruction of the second order kernels - measured by a chi-squared averaged over the whole experiment - is only about 8% of the first order contribution. Yet if we introduce an instant-dependent chi-square to measure the contribution of second order kernels at special events, we observe an up to 100% improvement. As may be expected, for translational stimuli the reconstructions are rather poor. The Gaussian-like representation could be a valuable aid in population coding with large number of neurons