A equação de Ramanujan-Nagell e algumas de suas generalizações

Dissertação (mestrado)—Universidade de Brasília, Departamento de Matemática, 2013.O objetivo deste trabalho é mostrar algumas técnicas para resolução de equações diofantinas. Métodos algébricos são ferramentas de grande utilidade para a resolução da equação equation x2 + 7 = yn, em que y = 2 ou Y é ímpar. O uso do método hipergeométrico traz um resultado recente (de 2008) no estudo da equação x2 + 7 =2n. m e técnicas algébricas garantem uma condição necessária para que essa última equação tenha solução. _______________________________________________________________________________________ ABSTRACTThe objective of this work is to show some techniques for solving Diophantine equations. Algebraic methods are useful tools for solving the equation x2 + 7 = yn, where y = 2 or y is odd. The use of the hypergeometric method brings a recent result (from 2008) in the study of the equation x2 + 7 = 2n.m and algebraic techniques ensure a necessary condition for the last equation to have a solution

Species Extinction Risk Might Increase Out Of Reserves: Allowances For Conservation Of Threatened Butterfly Actinote Quadra (lepidoptera: Nymphalidae) Under Global Warming

Climate change is an important factor affecting species dispersal and distribution through time and the accelerated global warming has currently concerned decision makers and conservationists. Because protected areas are spatially static, species extinction risk is generally expected to increase under climate change scenarios as a consequence of range shift and decrease. This study aims to understand the current conservation status of Actinote quadra, a neotropical threatened butterfly species, as well as predict how it will be in the future. By coupling ecological niche modeling and climatic simulations, we predicted the species distribution in different future global warming scenarios (2050 and 2070) and estimated the proportion of species range overlapping protected areas through time. Our findings showed a generalized decrease of the potential distribution of A. quadra in the end of 21st century, with the most prominent range loss predicted to occur out of protected areas. Although climate change will potentially drive A. quadra into reserves, the predicted range collapse would be enough to increase its extinction risk from vulnerable, like currently categorized, to the status of critically endangered in accordance to IUCN red list criteria. Taking into account the fragmented and discontinuous landscapes across the Atlantic Forest's hotspot, we propose a conservation strategy for A. quadra based on potential ecological corridors linking climatically suitable areas and discuss the need for amplifying and connecting the current protected areas to maintain this threatened species at longer time under a global warming scenario. (C) 2015 Associacao Brasileira de Ciencia Ecologica e Conservacao. Published by Elsevier Editora Ltda. All rights reserved.132159165FAPEG [2012/1026.700.1086]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

THE HERITAGE OF EUROPEAN INTERNATIONAL SOCIETY IN MULTIDIMENSIONAL PEACE OPERATIONS: LIBERIA AS A CASE STUDY

The present paper has as its central objective to analyze United Nations (UN) peace operations as a form of creating post-conflict States that carries a series of institutions that underpins what is understood as the International Society, firstly consolidated by European states in previous centuries. I rely on English School’s historical perspective on International Society in order to demonstrate the transmission of certain institutions through multidimensional peace operations, briefly exposing the United Nations Mission in Liberia (UNMIL) case. By analyzing some primary documents concerning the mission that took place in Liberia, it is possible to infer that UN multidimensional peace operations promotes institutions built within a European and Western international order.Key words: English School; International Society; Peace Operations; United Nations; UNMIL.O presente trabalho tem como objetivo central analisar as operações de paz da Organização das Nações Unidas (ONU) como uma forma de criar Estados pós-conflito que carregam uma série de instituições que sustentam o que é entendido como Sociedade Internacional, primeiramente consolidada pelos europeus nos séculos anteriores. O artigo baseia-se na perspectiva histórica da Escola Inglesa sobre a Sociedade Internacional, a fim de demonstrar a transmissão de certas instituições através das operações de paz multidimensionais, expondo o caso UNMIL. Ao analisar alguns documentos primários relativos à missão que ocorreu na Libéria, é possível inferir que as operações de paz multidimensionais da ONU promovem instituições construídas dentro de uma ordem internacional europeia e ocidental.Palavres Chave: Escola Inglesa; Sociedade Internacional; Operações de Paz; Nações Unidas; UNMIL

Purification of flavivirus VLPs by a two-step chromatographic process

Flaviviruses are enveloped viruses with positive-sense, single-stranded RNA, which are most commonly transmitted by infected mosquitoes. Besides for example dengue viruses (DENV), which have been already for decades posing challenges to public health worldwide, zika virus (ZIKV) and yellow fever virus (YFV) are flaviviruses that have caused significant outbreaks in the last few years. Thus, based on our experience of expressing virus-like particles (VLPs) of several different flaviviruses in recombinant mammalian cells, this work focuses on the development of efficient chromatographic purification processes for zika and yellow-fever VLPs. ZIKV has been discovered in 1947, and since 2007 it has caused isolated outbreaks in Pacific Islands. However, in 2015 it was identified for the first time in Brazil and then quickly spread to over 60 countries between 2015 and 2016. Although most zika patients are asymptomatic, in a small proportion of adults ZIKV infection can cause Guillain-Barré syndrome, and in fetuses of infected women it frequently causes serious congenital malformations, especially in the central nervous system. Since it can be transmitted also by the sexual route and can persist for very long periods in body fluids (including sperm), the development of a vaccine is needed to prevent the spread of the virus to non-endemic countries and to prevent outbreaks to periodically occur in regions where the virus is already circulating. Yellow fever virus is a highly lethal virus, which causes death in about 6-10% of non-vaccinated individuals. In past centuries, before the introduction of the current live-attenuated vaccine, 10% of the population of cities like Philadelphia (USA) and Barcelona (Spain) died in YF outbreaks. The current vaccine is very safe and provides life-long protection from a single dose. However, it can also cause fatal adverse effects in a small proportion of vaccines, and the egg-based production is limited in capacity. This latter fact led to worldwide vaccine shortages during an outbreak in Africa in 2016 and in Brazil in 2017-2018. Although the WHO introduced during the African outbreak in 2016 the use of a fractional (1/5) dose as an emergency measure to control outbreaks, even if using fractional doses of the current vaccine, shortage would be an issue if YF outbreaks spread and especially if it gets to be locally transmitted in Asia, where the mosquito vector is widespread. In this work, a two-step chromatographic process was developed for the purification of zika and yellow fever VLPs from CHO- and HEK293-derived cell culture supernatant, building on previous experience acquired on the purification of yellow fever whole virus from Vero cell culture (Pato et al., 2014, doi: 10.1016/j.vaccine.2014.02.036). The initial clarification of the cell culture suspension was performed by centrifugation and/or filtration, followed by anion exchange chromatography and then a multimodal chromatographic step. The anion exchanger used was a Q membrane adsorber, due to its easy scalability, simplicity to handle, absence of diffusional limitations, and good performance at high flow rates for the capture of large molecules such as VLPs. This capture step allowed a high degree of concentration and an efficient DNA removal. In order to enhance HCP removal, a CaptoCore 700 multimodal column was used in a flow-through mode, allowing contaminants to be adsorbed while VLPs were excluded by size. Samples from all steps of the process were characterized by immunoassays, total protein determination, SDS-PAGE and Western blot. The promising results obtained for zika and yellow fever VLPs indicate that this process could be potentially applied also to other flavivirus VLPs that we have been expressing in our lab, such as DENV1-4, SLEV, CPCV and ILHV. Overall, the presented downstream process could potentially represent a simple, robust and economic platform technology for the production of cell culture-derived recombinant flavivirus vaccines. Acknowledgements: T. P. Pato (Biomanguinhos, FIOCRUZ, Brazil) for fruitful discussions, and B. S. Graham (VRC, NIH, USA) for fruitful discussions and sharing reagents

International Society and the United Nations Peacebuilding: diffusing institutions and restoring “normalcy” in Liberia

Since its first peacekeeping operation, the United Nations (UN) broadened its normative framework to provide efficient responses to the turbulent reality of countries experiencing intrastate wars. Back in the 1990s, the UN acknowledged that intrastate conflict causes are structural and socially rooted, and therefore achieving peace in collapsing states would only be possible through the strategy labelled as peacebuilding, aimed at achieving longstanding peace through the reconstruction of the state in the post-conflict phase. Based on English School theorists, this paper aims to analyze how the UN peacebuilding policies can be associated with the strengthening of the commitment of war-torn states to institutions and rules that underpins the group of states known as “international society”. To illustrate the aforementioned argument, this work consists of a case study methodology that assess the United Nations Mission in Liberia (2003-2018).Since its first peacekeeping operation, the United Nations (UN) broadened its normative framework to provide efficient responses to the turbulent reality of countries experiencing intrastate wars. Back in the 1990s, the UN acknowledged that intrastate conflict causes are structural and socially rooted, and therefore achieving peace in collapsing states would only be possible through the strategy labelled as peacebuilding, aimed at achieving longstanding peace through the reconstruction of the state in the post-conflict phase. Based on English School theorists, this paper aims to analyze how the UN peacebuilding policies can be associated with the strengthening of the commitment of war-torn states to institutions and rules that underpins the group of states known as “international society”. To illustrate the aforementioned argument, this work consists of a case study methodology that assess the United Nations Mission in Liberia (2003-2018)

Estudo da eletro-oxidação de glicerol em superfícies de platina e ouro modificadas por adátomos metálicos

Orientador: Pablo Sebastian FernandezDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de QuímicaResumo: O objetivo geral dessa dissertação foi o estudo da eletro-oxidação de glicerol em meio alcalino em superfícies de ouro e platina, modificadas por adátomos metálicos. A modificação das superfícies foi feita por deposição sobrepotencial e adsorção irreversível, e os metais escolhidos para modificar os eletrodos foram cobre, chumbo e bismuto. Por meio de voltametria cíclica, foi concluído que o ouro foi desativado para a oxidação do glicerol após modificação com esses metais, observado pela redução na densidade de corrente registrada. A platina, por sua vez, foi desativada após modificação com cobre, ao passo que a modificação com bismuto promoveu a catálise, visto como um aumento na densidade de corrente. A adição de 10-5 M de óxido de bismuto ao eletrólito contendo glicerol em meio básico proporcionou o maior aumento em atividade e estabilidade do catalisador. Utilizando as técnicas de HPLC e FTIR, foi determinado que a adsorção do bismuto muda as vias de eletro-oxidação de glicerol da seguinte maneira: 1) inibe a formação de monóxido de carbono, um intermediário responsável pela desativação do catalisador, 2) promove a obtenção de ácido glicérico a partir do glicerol e 3) Reduz a oxidação total do glicerol à carbonatoAbstract: The main goal of this dissertation was to understand the glycerol electrooxidation on platinum and gold surfaces in alkaline media, modified by deposition of metal adatoms. Surface modification was done using underpotential deposition and irreversible adsorption, and the metals chosen to modify the surfaces were copper, lead and bismuth. Using cyclic voltammetry, it was determined that gold was deactivated to glycerol oxidation after modification with the three metals, which generated a reduction in the current density. Platinum was also deactivated after modification with copper, however, bismuth promoted the catalysis, increasing the current densities. The optimum condition for this enhancement, was the addition of 10-5 M of bismuth oxide to the electrolyte containing glycerol. Using the HPLC and FTIR techniques, it was determined that the adsorption of bismuth modified the electrooxidation pathways as follows: 1) inhibits the formation of carbon monoxide on platinum, a poisoning intermediate responsible for catalyst deactivation, 2) promotes the conversion of glycerol into glyceric acid, and 3) hinders the glycerol complete oxidation towards carbonateMestradoFísico-QuímicaMestre em Químic

Decision support based on digital twin simulation: a case study

The significance of Digital Twins is considered vital in the reshaping of the manufacturing field with the emergence of the fourth industrial revolution. The potential of applying the Digital Twin technology is being studied extensively as a key enabler of engineering cyber-physical systems. However, it is still in its infancy, and only a few scientific papers are describing its applicability in case-studies, prototypes or industrial systems. Bearing this in mind, this paper presents a comprehensive overview of Digital Twins in the manufacturing domain and defines a conceptual architecture that considers simulation capabilities to support the optimisation of production processes. The designed approach is applied to a proof-of-concept case study that considers a flexible production cell and uses the simulation of the system to dynamically support decision making to optimise the production processes when changes occur in the real production system.info:eu-repo/semantics/publishedVersio