Aplicação web para monitoramento e emissão de boletins de alerta da ferrugem do cafeeiro utilizando árvores de decisão.

A ferrugem, causada pelo fungo Hemileia vastatrix Berk. et Br., é a principal doença do cafeeiro em todo o mundo, causando prejuízos de 35% em média e podendo chegar a mais de 50% de perda na produção (ZAMBOLIN, et al., 2002). Para esse tipo de doença, existem diversos modelos de alerta, porém poucos foram validados e não se tem registro de uso continuado. A partir disso, este trabalho descreve uma aplicação desenvolvida para analisar e informar o risco de epidemias da ferrugem do cafeeiro, no âmbito de estações de avisos fitossanitários da Fundação PROCAFÉ, localizadas nos municípios de Boa Esperança, Carmo de Minas e Varginha, no Estado de Minas Gerais

Shadows of black holes with dark matter halo

We investigate the shadow of an exact black hole solution of Einstein's equations recently proposed by Cardoso et al., to describe a supermassive black hole immersed in a dark matter halo. We analyze and discuss the light rings and the gravitational lensing of this spacetime comparing them with an isolated Schwarzschild black hole. Using backward ray-tracing techniques, we study the shadows cast by such black hole when illuminated by a celestial sphere that emits radiation isotropically. We find that when the dark matter distribution concentrates near the event horizon of the black hole, multiple light rings emerge. In this high compactness regime, the shadows and gravitational lensing are significantly different from the Schwarzschild one. We also use the M87* and SgrA* shadow data, obtained by the Event Horizon Telescope collaboration, to constrain the parameters of the dark matter halo.Comment: 8 pages, 6 figure

Do the words matter? An analysis of the linguistic sentiment of earnings conference calls and abnormal stock returns in brazilian companies

In finance and accounting literature, different aspects are presented as possible factors related to stock returns. More recently, studies have been dedicated to analyzing the potential influence of the tone and sentiment of corporate reports, newspaper articles, press releases, and investor message boards on stock prices. Thus, based on assumptions of Legitimacy Theory, we investigate whether cumulative abnormal returns (CAR) on the stocks of Brazilian listed companies are associated with the linguistic sentiment of quarterly earnings conference calls. Using a sample of 78 observations related to the conference calls of 24 companies listed in the Novo Mercado segment in 2016-2017, we measured CAR using the market model and the linguistic sentiment of earnings conference calls using IBM’s Watson Natural Language Understanding platform. An analysis of the results of statistical tests such as descriptive results, correlation matrix, and correspondence analysis enables it to be inferred that, in general, there is a positive association between cumulative abnormal returns and the optimism sentiment of quarterly conference calls. Thus, it is conjectured the possibility that the speeches made by managers in conference calls legitimize company performance in the market, by altering the perception of investors in the stock market and leading to implications for the value of the stocks traded.info:eu-repo/semantics/publishedVersio

Tamanho da partícula afeta a digestibilidade do farelo de girassol em suínos.

bitstream/item/58781/1/CUsersPiazzonDocuments153.pd

Emerging risks of non-native species escapes from aquaculture: Call for policy improvements in China and other developing countries

Global aquaculture relies heavily on the farming of non-native aquatic species (hereafter, NAS). NAS escapes from aquaculture facilities can result in serious aquatic bio-invasions, which has been an important issue in the FAO Blue Growth Initiative. A regulatory quagmire regarding NAS farming and escapes, however, exists in most developing countries. We discuss aquaculture expansion and NAS escapes, illustrate emerging risks and propose recommendations for improved aquaculture management across developing countries and particularly for China. In China, 68 NAS are known to have successfully established feral populations in natural habitats due to recurrent leakages or escapes; among the 68 NAS, 52 represent risks to native aquatic ecosystems. In addition to affecting a country's own biodiversity and ecosystem functions, NAS escapees can also threaten the biosecurity of shared waters in neighbouring countries. Policy implications. Non-native aquatic species (NAS) escapes have already had adverse ecological effects in China and other developing countries. The importance of this problem, however, is not adequately recognized by current conservation policies in developing countries. To conserve biodiversity and to support the goal of FAO's sustainable aquaculture, developing countries should now take responsible actions to address NAS escapes through policy and management improvements. Specifically, these countries should pass comprehensive legislation, establish effective agencies and national standards and planning and enhance integrated research and education to deal with risk assessment, prevention, monitoring and control of NAS escapes. Given that China is the world's largest aquacultural producer, China can create a model for other developing countries that will increase the biosecurity and sustainability of global aquaculture