Chaves mais pequenas para criptossistemas de McEliece usando codificadores convolucionais

The arrival of the quantum computing era is a real threat to the confidentiality and integrity of digital communications. So, it is urgent to develop alternative cryptographic techniques that are resilient to quantum computing. This is the goal of pos-quantum cryptography. The code-based cryptosystem called Classical McEliece Cryptosystem remains one of the most promising postquantum alternatives. However, the main drawback of this system is that the public key is much larger than in the other alternatives. In this thesis we study the algebraic properties of this type of cryptosystems and present a new variant that uses a convolutional encoder to mask the so-called Generalized Reed- Solomon code. We conduct a cryptanalysis of this new variant to show that high levels of security can be achieved using significant smaller keys than in the existing variants of the McEliece scheme. We illustrate the advantages of the proposed cryptosystem by presenting several practical examples.A chegada da era da computação quântica é uma ameaça real à confidencialidade e integridade das comunicações digitais. É, por isso, urgente desenvolver técnicas criptográficas alternativas que sejam resilientes à computação quântica. Este é o objetivo da criptografia pós-quântica. O Criptossistema de McEliece continua a ser uma das alternativas pós-quânticas mais promissora, contudo, a sua principal desvantagem é o tamanho da chave pública, uma vez que é muito maior do que o das outras alternativas. Nesta tese estudamos as propriedades algébricas deste tipo de criptossistemas e apresentamos uma nova variante que usa um codificador convolucional para mascarar o código de Generalized Reed-Solomon. Conduzimos uma criptoanálise dessa nova variante para mostrar que altos níveis de segurança podem ser alcançados usando uma chave significativamente menor do que as variantes existentes do esquema de McEliece. Ilustramos, assim, as vantagens do criptossistema proposto apresentando vários exemplos práticos.Programa Doutoral em Matemátic

Plantar povoações no território: (re)construindo a urbanização da capitania do Piauí, 1697-1761

The Piauí province´s urbanization has kept up with since late 17th century a complex process dealt among Portuguese Crown, the regal representatives, the network woven by the Casa da Torre and by the resident population in its countryside. What it was content of Rodelas countryside has begun to build with territorial identity since the foundation of first parish in 1697. Structuring itself discontinuously in time and space, the Piauí had reformed in 1758, year of creation of its autonomous government. And had became urban in 1761 when the king D. José I and marquis of Pombal had framed by the royal letter written in June 19 a territory formed by six towns and one city. Thus, this paper purposes to reconstructing the Piauí province according to agents involved in the urbanization processes. It proposes to deconstructing Crown´s polices by means towns strategically placed in territory aiming at control and "remedy" of routine injustices practiced in Piauí´s hinterlands. The method of presenting this reconstruction draws on interconnection between text (manuscript documents) and image (maps and photography) which in their discourses have represented a Piauí as space of experiences apprehended as much in official dimension as inhabitant´s everyday life.A urbanização da capitania do Piauí acompanhou, desde finais do século XVII, um complexo processo negociado entre a Coroa portuguesa, os representantes régios, a rede clientelar urdida pela Casa da Torre e a população residente em seus sertões. O que antes era conteúdo dos sertões de Rodelas passou a construir-se como identidade territorial a partir da fundação da primeira freguesia, em 1697, dedicada a Nossa Senhora da Vitória. Estruturando-se descontinuamente no tempo e no espaço, o Piauí reforma-se em 1758, ano da autonomização do seu governo. E fez-se urbano em 1761, quando D. José I e o marquês de Pombal equacionaram, por meio da carta régia de 19 de junho, um território formado por seis vilas e uma cidade. Nessa direção, o objetivo deste artigo consiste em reconstruir o processo de formação da capitania do Piauí segundo os agentes envolvidos na urbanização do território. Propõe-se descortinar as políticas da Coroa por meio da oficialização de povoações estrategicamente locadas no território visando o controle e o "remédio" das injustiças rotineiras do Piauí. O método de apresentar essa reconstrução vale-se da interconexão entre texto (documentação manuscrita) e imagem (mapas e fotografias), que em suas entrelinhas representam um Piauí como espaço de experiências sentidas tanto na dimensão oficial quanto no cotidiano dos seus moradores

Método da descida infinita

Mestrado em Matemática e AplicaçõesFermat teve um papel muito importante na Teoria dos N´umeros. Esta cont´em problemas muito dif´ıceis que fascinaram (e ainda fascinam) v´arios matem´aticos. Refira-se, em particular, as propriedades dos n´umeros inteiros positivos e dos n´umeros primos que despertaram interesse em Fermat. Sobre estes existem problemas bastante dif´ıceis de provar, mas que, contrariamente, possuem uma formula¸c˜ao bastante simples. Perante a dificuldade em demonstrar alguns destes resultados, Fermat desenvolveu uma t´ecnica de demonstra¸c˜ao, conhecida pela designa ¸c˜ao de M´etodo da Descida Infinita. Resumidamente, o m´etodo prova que certas propriedades ou rela¸c˜oes s˜ao imposs´ıveis para inteiros ao provar-se que, se fossem v´alidas para alguns n´umeros, seriam v´alidas para alguns n´umeros mais pequenos; usando o mesmo argumento, seriam v´alidas para alguns n´umeros ainda mais pequenos, e assim sucessivamente, o que ´e imposs´ıvel devido ao facto de que uma sequˆencia de n´umeros inteiros positivos n˜ao pode decrescer infinitamente. Fermat descreveu, em linhas gerais, o seu m´etodo, enunciando as v´arias proposi¸c˜oes nas quais o aplicou, numa carta dirigida a Carcavi em 1659. Era atrav´es de correspondˆencias por carta que Fermat partilhava as suas descobertas e nesta desafiou outros matem´aticos a aplicar o seu m´etodo na demonstra¸c˜ao de v´arios resultados. Esta tese teve por objetivo reproduzir as demonstra¸c˜oes de algumas proposi¸c˜oes referidas na carta a Carcavi, as quais Fermat diz ter demonstrado pelo M´etodo da Descida Infinita.Fermat played a very important role in the Theory of Numbers. This area contains very difficult problems which fascinated (and still does) several mathematicians. Particularly, the properties of positive whole numbers and prime numbers which arouse Fermat’s interest. About these, there are problems which very hard to prove, but, in an opposite way, are very easy to state. In the presence of the difficulty to demonstrate some of these results, Fermat developed a demonstration technique known as the Method of Infinite Descent. In sum, the method proves that certain properties or relations are impossible for integers, proving that if they were valid to some numbers, would also be valid for some smaller numbers; using the same argument, would be valid for some even smaller numbers, and so on, which is impossible due to the fact that a sequence of positive whole numbers cannot indefinitely decrease. Fermat described his method in a letter to Carcavi in 1659, in general terms, expressing several propositions to which he applied it. It was by his letters that Fermat shared his discoveries and in this one he challenged other mathematicians to apply his method to give proofs of several results. The purpose of this thesis is to reproduce the demonstrations of some propositions referred in the letter to Carcavi, the ones that Fermat says have been demonstrated by the Method of Infinite Descent

Exploring the antioxidant, anti-inflammatory and antiallergic potential of Brazilian propolis in monocytes

Propolis is a bee product used since ancient times due to its diverse biological applications. We aimed to investigate the antioxidant and anti-inflammatory action of Brazilian propolis in THP-1 cells stimulated with 1‐fluoro‐2,4‐dinitrobenzene (DNFB) or lipopolysaccharide (LPS). Methods: Cell viability was assessed by resazurin assay, antioxidant activity was evaluated by DPPH assay, superoxide dismutase (SOD) 1 and 2 activity was evaluated by colorimetric assay. CD86 expression was determined by flow cytometry. IL-1β and HMOX-1 were analysed by Western blot. Results: Propolis did not affect cell viability and exhibited a potent antioxidant activity. Propolis alone induced SOD 1 activity. LPS stimulated SOD2, concomitantly or not with propolis. In the presence of LPS, propolis induced a higher HMOX-1 expression. Propolis inhibited CD86 expression stimulated by DNFB. LPS induced pro-IL-1β expression and propolis did not affect its action. Conclusion: Propolis exhibited an antioxidant action in a cell-free system and in a cell based-model. Propolis exerted an anti-inflammatory/antiallergic action, probably due to its antioxidant activity

Icodextrin reduces insulin resistance in non-diabetic patients undergoing automated peritoneal dialysis: results of a randomized controlled trial (STARCH)

Insulin resistance is a common risk factor in chronic kidney disease patients contributing to the high cardiovascular burden, even in the absence of diabetes. Glucose-based peritoneal dialysis (PD) solutions are thought to intensify insulin resistance due to the continuous glucose absorption from the peritoneal cavity. The aim of our study was to analyse the effect of the substitution of glucose for icodextrin on insulin resistance in non-diabetic PD patients in a multicentric randomized clinical trial. This was a multicenter, open-label study with balanced randomization (1:1) and two parallel-groups. Inclusion criteria were non-diabetic adult patients on automated peritoneal dialysis (APD) for at least 3 months on therapy prior to randomization. Patients assigned to the intervention group were treated with 2L of icodextrin 7.5%, and the control group with glucose 2.5% during the long dwell and, at night in the cycler, with a prescription of standard glucose-based PD solution only in both groups. The primary end-point was the change in insulin resistance measured by homeostatic model assessment (HOMA) index at 90 days. Sixty patients were included in the intervention (n = 33) or the control (n = 27) groups. There was no difference between groups at baseline. After adjustment for pre-intervention HOMA index levels, the group treated with icodextrin had the lower post-intervention levels at 90 days in both intention to treat [1.49 (95% CI: 1.23-1.74) versus 1.89 (95% CI: 1.62-2.17)], (F = 4.643, P = 0.03, partial η(2) = 0.078); and the treated analysis [1.47 (95% CI: 1.01-1.84) versus 2.18 (95% CI: 1.81-2.55)], (F = 7.488, P = 0.01, partial η(2) = 0.195). The substitution of glucose for icodextrin for the long dwell improved insulin resistance measured by HOMA index in non-diabetic APD patients

Avaliação da dissimilaridade genética em genótipos de bananeira (Musa spp.) via marcadores RAPD Evaluation of genetics dissimilarity in banana tree genotypes (Musa spp.) by means of RAPD markers

A bananicultura possui grande importância econômica e social. A UENF, por meio do Laboratório de Melhoramento Genético Vegetal iniciou um trabalho de introdução de cultivares de bananeira. Foram introduzidas cultivares com procedência da Embrapa Mandioca e Fruticultura e Embrapa Amazônia Ocidental. O objetivo deste trabalho foi realizar um estudo de diversidade genética entre 21 cultivares e obter a correta identificação de possíveis genótipos introduzidos na UENF. Foram avaliados os seguintes genótipos: Fhia 18, Prata-Anã, UENF 1526, Pacovan, Caipira, Maçã, UENF 1527, Nanicão, Thap Maeo, UENF 1528, UENF 1529, Grande Naine, Ambrósia, Bucaneiro, Calipso, PV42-68, PV42-85, PV42-142, ST12-31, Calcutta e BB da França. A análise de divergência genética foi feita com base na caracterização molecular, utilizando-se da técnica RAPD. Para serem obtidas marcas moleculares RAPD, foram utilizados 31 "primers", gerando um total de 94 marcas totais. Os resultados mostraram que os marcadores moleculares RAPD foram eficazes em revelar a existência de diversidade genética entre os 21 genótipos de bananeira. Na interpretação das análises moleculares, foi utilizado o complemento aritmético do Índice de Jaccard. Com base nas análises de agrupamento hierárquicas UPGMA e o método de otimização de Tocher, essa diversidade pôde ser observada pela presença de genótipos similares e divergentes.<br>Banana is a very important social and economic crop. The introduction of of banana cultivars was initiated through the Plant Genetics Laboratory at UENF. Cultivars from Embrapa Cassava and Tropical Fruits and Western Amazon were introduced. The objective of the present work was to analyze the genetic dissimilarity between 21 cultivars and obtain the correct identification of the possible genotypes introduced at UENF. The following genotypes were evaluated: Fhia 18, Prata Anã, UENF 1526, Pacovan, Caipira, Maçã, UENF 1527, Nanicão, Thap Maeo, UENF 1528, UENF 1529, Grande Naine, Ambrósia, Bucaneiro, Calipso, PV42-68, PV42-85, PV42-142, ST12-31, Calcutta and BB da França. The genetic dissimilarity was carried out using RAPD molecular markers. Thirty-one primers were used, generating a total of 94 bands. The RAPD molecular markers were capable to accurately reveal the existence of genetics diversity among the 21 banana genotypes. For data interpretation, the Jaccard index was used. Based on cluster analysis UPGMA and the Tocher method, the dissimilarity could be observed by the presence of similar and dissimilar genotypes