20 research outputs found

    A comparison about the predictive ability of FCGARCH, facing EGARCH and GJR

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    In order to study the volatility of a stock market, several volatility models have been created, studied and improved throughout the time. Due to the extreme and actual situation in international stock market’s volatility, the main objective of this thesis is to focus on the FCGARCH model created by Medeiros and Veiga (2009), and compare it with some of the most popular asymmetric autoregressive conditional heteroskedasticity models, such as EGARCH and GJR. Using the daily returns of 5 most important international stock market indexes, such as S&P500 (USA), FTSE100 (UK), Nikkei225 (Japan), DAX30 (Germany) and PSI20 (Portugal), and using the Harvey-Newbold test, we are going to check which of these models is the best one to fit the conditional heteroskedastic volatilities of the returns of the indexes under study. In order to make the thesis possible, I have created the FCGARCH, EGARCH and GJR models’ codes in Matlab, with the help of my co-supervisor, Doctor Renato Costa, as well as used the Harvey-Newbold test in E-views, created by my supervisor, Professor José Dias Curto. According to the estimation results, in the in-sample analysis, when looking at the Quasi-Maximum-Log likelihood goodness-of-fit measure, the FCGARCH fits most of the indexes’ returns under study, where, in the out-of-sample analysis, according to the Harvey-Newbold test for multiple forecasts encompassing, the results show that the GJR seems to encompass the other two models in most of the indexes, thus concluding that GJR seems to be the best model to forecast the volatility.Para que possamos estudar a volatilidade de uma ação, muitos foram os modelos criados, estudados e melhorados ao longo do tempo. Devido à extrema e atual situação da volatilidade nos mercados acionistas internacionais, o principal objetivo desta tese é focar no modelo FCGARCH, criado por Medeiros e Veiga (2009), e compará-lo com alguns dos mais importantes modelos heterocedásticos, autorregressivos e assimétricos, como o EGARCH e o GJR. Utilizando os retornos diários de 5 dos índices mais importantes a nível internacional, tais como S&P500 (EUA), FTSE100 (RU), Nikkei225 (Japão), DAX30 (Alemanha) e PSI20 (Portugal), e usando o teste de Harvey-Newbold, vamos descobrir qual dos modelos apresentados é o que melhor descreve o comportamento das variâncias condicionais heterocedásticas dos retornos dos índices sob estudo. Para que a criação desta tese fosse possível, tive de criar os códigos dos modelos do FCGARCH, EGARCH e GJR no Matlab, com a ajuda do meu co-orientador, o Doutor Renato Costa, assim como usar o teste de Harvey-Newbold no E-views, criado pelo meu orientador, o Professor José Dias Curto. De acordo com os resultados estimados, na análise in-sample, ao olharmos para a medida de quase-máxima-verosimilhança, o FCGARCH descreve bem a maioria dos retornos sob estudo, enquanto, na análise out-of-sample, de acordo com o teste de Harvey-Newbold para a abrangência de previsões, os resultados demonstram que o GJR parece abranger os outros dois modelos na maioria dos índices, desta forma concluindo que o GJR parece ser o melhor modelo para prever a volatilidade

    Pervasive gaps in Amazonian ecological research

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    Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

    Pervasive gaps in Amazonian ecological research

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    Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

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    Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

    Pervasive gaps in Amazonian ecological research

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    Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

    Clinical And Genotypic Spectrum Of Chronic Granulomatous Disease In 71 Latin American Patients: First Report From The Lasid Registry

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    Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Aim. We analyzed data from 71 patients with chronic granulomatous disease (CGD) with a confirmed genetic diagnosis, registered in the online Latin American Society of Primary Immunodeficiencies (LASID) database. Results. Latin American CGD patients presented with recurrent and severe infections caused by several organisms. The mean age at disease onset was 23.9 months, and the mean age at CGD diagnosis was 52.7 months. Recurrent pneumonia was the most frequent clinical condition (76.8%), followed by lymphadenopathy (59.4%), granulomata (49.3%), skin infections (42%), chronic diarrhea (41.9%), otitis (29%), sepsis (23.2%), abscesses (21.7%), recurrent urinary tract infection (20.3%), and osteomyelitis (15.9%). Adverse reactions to bacillus Calmette-Guerin (BCG) vaccination were identified in 30% of the studied Latin American CGD cases. The genetic diagnoses of the 71 patients revealed 53 patients from 47 families with heterogeneous mutations in the CYBB gene (five novel mutations: p.W361G, p.C282X, p.W483R, p.R226X, and p.Q93X), 16 patients with the common deletion c.75_76 del.GT in exon 2 of NCF1 gene, and two patients with mutations in the CYBA gene. Conclusion. The majority of Latin American CGD patients carry a hemizygous mutation in the CYBB gene. They also presented a wide range of clinical manifestations most frequently bacterial and fungal infections of the respiratory tract, skin, and lymph nodes. Thirty percent of the Latin American CGD patients presented adverse reactions to BCG, indicating that this vaccine should be avoided in these patients. (C) 2015 Wiley Periodicals, Inc.621221012107Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Agence Nationale de la Recherche [ANR13-ISV3-0001-01]Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

    Homenagem Casa dos Estudantes do Império - 50 Anos | Testemunhos, Vivências, Documentos

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    Os textos incluídos nesta obra são transcrições das intervenções feitas pelos participantes nas diversas sessões da homenagem à Casa dos Estudantes do Império, realizadas entre 2014 e 2015. Estas intervenções foram gravadas através de meios audiovisuais e posteriormente editadas para efeitos de publicação. A presente edição segue a grafia do Acordo Ortográfico, exceto nos casos em que os autores quiseram manter a antiga grafia.CML – Câmara Municipal de Lisboa; Camões – Instituto da Cooperação e da Língua; Fundação Calouste Gulbenkianinfo:eu-repo/semantics/publishedVersio

    Resumos concluídos - Fisioterapia

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    Resumos concluídos - Fisioterapi

    Neotropical freshwater fisheries : A dataset of occurrence and abundance of freshwater fishes in the Neotropics

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    The Neotropical region hosts 4225 freshwater fish species, ranking first among the world's most diverse regions for freshwater fishes. Our NEOTROPICAL FRESHWATER FISHES data set is the first to produce a large-scale Neotropical freshwater fish inventory, covering the entire Neotropical region from Mexico and the Caribbean in the north to the southern limits in Argentina, Paraguay, Chile, and Uruguay. We compiled 185,787 distribution records, with unique georeferenced coordinates, for the 4225 species, represented by occurrence and abundance data. The number of species for the most numerous orders are as follows: Characiformes (1289), Siluriformes (1384), Cichliformes (354), Cyprinodontiformes (245), and Gymnotiformes (135). The most recorded species was the characid Astyanax fasciatus (4696 records). We registered 116,802 distribution records for native species, compared to 1802 distribution records for nonnative species. The main aim of the NEOTROPICAL FRESHWATER FISHES data set was to make these occurrence and abundance data accessible for international researchers to develop ecological and macroecological studies, from local to regional scales, with focal fish species, families, or orders. We anticipate that the NEOTROPICAL FRESHWATER FISHES data set will be valuable for studies on a wide range of ecological processes, such as trophic cascades, fishery pressure, the effects of habitat loss and fragmentation, and the impacts of species invasion and climate change. There are no copyright restrictions on the data, and please cite this data paper when using the data in publications

    Brazilian Flora 2020: Leveraging the power of a collaborative scientific network

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    International audienceThe shortage of reliable primary taxonomic data limits the description of biological taxa and the understanding of biodiversity patterns and processes, complicating biogeographical, ecological, and evolutionary studies. This deficit creates a significant taxonomic impediment to biodiversity research and conservation planning. The taxonomic impediment and the biodiversity crisis are widely recognized, highlighting the urgent need for reliable taxonomic data. Over the past decade, numerous countries worldwide have devoted considerable effort to Target 1 of the Global Strategy for Plant Conservation (GSPC), which called for the preparation of a working list of all known plant species by 2010 and an online world Flora by 2020. Brazil is a megadiverse country, home to more of the world's known plant species than any other country. Despite that, Flora Brasiliensis, concluded in 1906, was the last comprehensive treatment of the Brazilian flora. The lack of accurate estimates of the number of species of algae, fungi, and plants occurring in Brazil contributes to the prevailing taxonomic impediment and delays progress towards the GSPC targets. Over the past 12 years, a legion of taxonomists motivated to meet Target 1 of the GSPC, worked together to gather and integrate knowledge on the algal, plant, and fungal diversity of Brazil. Overall, a team of about 980 taxonomists joined efforts in a highly collaborative project that used cybertaxonomy to prepare an updated Flora of Brazil, showing the power of scientific collaboration to reach ambitious goals. This paper presents an overview of the Brazilian Flora 2020 and provides taxonomic and spatial updates on the algae, fungi, and plants found in one of the world's most biodiverse countries. We further identify collection gaps and summarize future goals that extend beyond 2020. Our results show that Brazil is home to 46,975 native species of algae, fungi, and plants, of which 19,669 are endemic to the country. The data compiled to date suggests that the Atlantic Rainforest might be the most diverse Brazilian domain for all plant groups except gymnosperms, which are most diverse in the Amazon. However, scientific knowledge of Brazilian diversity is still unequally distributed, with the Atlantic Rainforest and the Cerrado being the most intensively sampled and studied biomes in the country. In times of “scientific reductionism”, with botanical and mycological sciences suffering pervasive depreciation in recent decades, the first online Flora of Brazil 2020 significantly enhanced the quality and quantity of taxonomic data available for algae, fungi, and plants from Brazil. This project also made all the information freely available online, providing a firm foundation for future research and for the management, conservation, and sustainable use of the Brazilian funga and flora
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