Subsets of groups in public-key cryptography

We suggest the usage of algebraic subsets instead of subgroups in public-key cryptography. In particular, we present the subset version of two protocols introduced by Shpilrain and Ushakov with some examples in ascending HNN-extensions of free-abelian groups and discuss their resistance to length and distance based attacks. We also introduce several new group theoretic problems arising from this work.Comment: 14 pages, comments welcome

Estudo da ligação aço-betão para vigas mistas com perfis metálicos enformados a frio

Dissertação de mestrado em Engenharia CivilA indústria da construção é caracterizada pela sua intensa atividade a nível global, o que tem implicações negativas no meio ambiente que resultam em parte dos materiais utilizados, nomeadamente o aço e o betão. Estima-se que a indústria da construção venha a crescer ainda mais nos próximos anos tornando-se necessário adotar praticas que garantam a utilização dos recursos naturais de forma mais sustentável. Os pavimentos mistos em aço e betão são uma solução construtiva que utiliza uma chapa colaborante sobre a qual se coloca a camada de betão. Este sistema estrutural atua de modo eficiente, ficando a chapa sujeita a esforços de tração e o betão a esforços de compressão. O sistema utiliza uma menor quantidade de material resultando em estruturas mais leves, e para além disso, dispensa a utilização de cofragem,sendo uma solução que requer pouco tempo para ser implementada. O presente trabalho foca-se no estudo de dois sistemas de conexão com características inovadoras a aplicar num sistema de construtivo para pavimentos mistos que apresenta também características inovadoras. O sistema construtivo é constituído por perfis enformados a frio de tipo C que se associam entre si formando uma secção em U que é preenchida com betão aproveitando a altura das lajes para criar a camada de compressão. Com o objetivo de estudar a contribuição dos sistemas de conexão propostos, é desenvolvida uma campanha experimental composta por ensaios do tipo push-out, que é complementada com a análise numérica dos modelos ensaiados. Para tal, foi desenhado um modelo de provete do tipo push-out tendo em conta o tipo de ligação entre o betão e o aço existente no sistema de viga mista proposto. Com base neste foram testados vários provetes de modo a estudar a influência de diferentes fatores na ligação entre os materiais.The construction industry is characterized by its intense activity at a global level which has negative implications for the environment that result in part of the materials used, namely steel and concrete. It is estimated that the construction industry will grow even more in the coming years, making it necessary to adopt practices that guarantee the use of natural resources in a sustainable way. The composite floors in steel and concrete are a constructive solution that uses a corrugated steel sheet where the concrete is poured. This structural system works efficiently as the steel sheet is subjected to tensile stresses and the concrete to compressive stresses. The system uses a smaller amount of material, resulting in lighter structures, and in addition, it does not require the use of formwork, being a solution that requires little time to be implemented. The present work focuses on the study of two connection systems with innovative characteristics to be applied in a construction system for mixed floors that also presents innovative characteristics. The construction system consists of cold-formed C-type profiles that are joined together forming a U-shaped section that is filled with concrete, taking advantage of the height of the slabs to create a compression layer. In order to study the contribution of the proposed connection systems, an experimental campaign consisting of push-out tests which is complemented with the numerical analysis of the tested models. To this end, a push-out specimen model was designed considering the type of connection between the concrete and the steel existing in the proposed mixed beam system. Based on this, several specimens were tested in order to study the influence of different factors on the connection between the materials

Cutaneous manifestations associated with SARS-CoV-2: an emerging topic in a pandemic era

A 70-year-old man was admitted to our COVID-19 ward with thoracalgia, productive mucus cough, fatigue and erythematous–violaceous macules on the inner side of feet and interdigital regions. The patient was started on oxygen and dexamethasone. On the day of discharge, he maintained the skin changes despite the resolution of COVID-19 symptoms. A 57-year-old woman initially presented with diffuse urticarial rash on the cervical and chest region. Oral cetirizine was started, and pruritus improved. Thirty days after the discharge, the patient maintained the rash, but without pruritus. A 49-year-old man was admitted with thoracalgia, shortness of breath, dry cough and urticarial rash on the cervical and chest region. The patient was treated with cetirizine. The pruritus improved, and 5 days after discharge, the urticarial areas completely disappeared.info:eu-repo/semantics/publishedVersio

Integrated sizing and scheduling of wind/PV/diesel/battery isolated systems

In this paper we address the optimal sizing and scheduling of isolated hybrid systems using an optimization framework. The hybrid system features wind and photovoltaic conversion systems, batteries and diesel backup generators to supply electricity demand. A Mixed-Integer Linear Programming formulation is used to model system behavior over a time horizon of one year, considering hourly changes in both the availability of renewable resources and energy demand. The optimal solution is achieved with respect to the minimization of the levelized cost of energy (LCOE) over a lifetime of 20 years. Results for a case study show that the most economical solution features all four postulated subsystems

Modelação e optimização do dimensionamento de um sistema electroprodutor híbrido isolado

Tese de mestrado integrado em Engenharia da Energia e do Ambiente, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2014A falta de acesso a serviços de energia afecta milhões de pessoas por todo o mundo. Considerando ainda as regiões onde o acesso a electricidade é efectuado por queima de combustíveis fósseis, vulneráveis às variações de custo de combustível, torna-se urgente promover o acesso a serviços de energia limpos e economicamente viáveis. Uma potencial solução é a implementação de sistemas híbridos isolados que contem com os recursos renováveis locais. Neste trabalho é desenvolvida uma metodologia de optimização do dimensionamento e escalonamento para sistemas híbridos isolados que reúnam as tecnologias de conversão eólica e fotovoltaica, baterias e geração a diesel. O objectivo é auxiliar o decisor do projecto a determinar o número de equipamentos a instalar de cada tecnologia. O dimensionamento óptimo é alcançado minimizando o investimento total para 20 anos de vida útil do projecto. Determina-se deste modo o custo de energia ou LCOE (€/kWh). A metodologia consiste num modelo de dimensionamento e escalonamento que avalia a cada hora o balanço de energia produção/consumo, para 1 ano de dados climáticos. A metodologia desenvolvida é um problema de programação linear inteira mista e é aplicada na plataforma GAMS. São analisadas e comparadas diversas configurações de sistemas híbridos e é efectuada a análise de sensibilidade a factores económicos como o custo do diesel. É efectuada uma análise climática demonstrando a aplicabilidade da metodologia desenvolvida a diferentes condições climáticas. Os resultados verificam que a implementação de sistemas híbridos isolados é a opção economicamente mais viável nos cenários considerados. As melhores soluções económicas são as que aplicam os quatro subsistemas propostos: eólica, fotovoltaica, baterias e geradores a diesel.The lack of energy services affects millions of people all over the world. Considering yet the regions where the access to electricity is done by fossil fuels, vulnerable to cost variations, it becomes urgent to promote access to sustainable energy services both environment-friendly and economically viable. One potential solution is the implementation of isolated hybrid systems that rely on local renewable energy sources. In this work it is developed a methodology for the optimal sizing and scheduling for isolated hybrid systems that count with wind and photovoltaic conversion technologies, batteries and diesel generators. The goal is to help the project manager to determine the number of equipments to install of each technology. The optimal sizing is achieved by minimizing the total cost during 20 years of the useful life of the project. With that, it is possible to determine the cost of energy or LCOE (€/kWh). The methodology consists on a sizing and scheduling model that evaluates in each hour the energy balance of production/consumption, for one year of climate data. The developed methodology is a mixed integer linear programming problem and is applied in the GAMS platform. Various configurations of hybrid systems are analyzed and compared and a sensitivity analysis to economic factors like diesel cost is performed. Also a climate analysis is performed to conclude about the applicability of the developed methodology in different climates. The results demonstrate that the implementation of hybrid systems is the most viable economical option in the considered scenarios. The most economic solutions are the ones that include the four subsystems proposed: wind, photovoltaic, batteries and diesel generators

Challenges in characterization of GNSS precise positioning systems for automotive

Autonomous driving is currently one of the main focuses of attention in the automotive industry. A requirement for efficient and safe driving of autonomous vehicles is the ability to precisely pinpoint the location of the vehicle, in the decimeter- to centimeter-level on a global scale. GNSS is expected to play a major role in providing accurate absolute and global positioning, yet many challenges arise in dense urban environments due to lack of line-of-sight to satellites and multi-path, decreasing availability and accuracy. Also, the position accuracy announced by GNSS receiver manufacturers is rather optimistic, typically obtained in best-case scenarios. However, this is rarely encountered in real-world driving conditions, especially in urban areas, leading to a mismatch between receiver specification and real world performance. This paper provides a systematic study regarding the requirements, methods, and solutions available for the characterization/evaluation of a GNSS po- sitioning system in real world driving conditions. An architecture for a precise Automotive Global Reference System (centimeter-level), able to characterize a decimeter-level accuracy GNSS position- ing system in dynamic conditions, is proposed. To the best of authors’ knowledge, such a study is not available in the literature.This work has been supported by: European Structural and Investment Funds in the FEDER component, through the Operational Competitiveness and Internationalization Programme (COMPETE 2020) [Project no 037902; Funding Reference: POCI-01-0247-FEDER-037902]

Peripheral nervous system plasmalogens regulate Schwann cell differentiation and myelination

Rhizomelic chondrodysplasia punctata (RCDP) is a developmental disorder characterized by hypotonia, cataracts, abnormal ossification, impaired motor development, and intellectual disability. The underlying etiology of RCDP is a deficiency in the biosynthesis of ether phospholipids, of which plasmalogens are the most abundant form in nervous tissue and myelin; however, the role of plasmalogens in the peripheral nervous system is poorly defined. Here, we used mouse models of RCDP and analyzed the consequence of plasmalogen deficiency in peripheral nerves. We determined that plasmalogens are crucial for Schwann cell development and differentiation and that plasmalogen defects impaired radial sorting, myelination, and myelin structure. Plasmalogen insufficiency resulted in defective protein kinase B (AKT) phosphorylation and subsequent signaling, causing overt activation of glycogen synthase kinase 3β (GSK3β) in nerves of mutant mice. Treatment with GSK3β inhibitors, lithium, or 4-benzyl-2-methyl-1,2,4-thiadiazolidine-3,5-dione (TDZD-8) restored Schwann cell defects, effectively bypassing plasmalogen deficiency. Our results demonstrate the requirement of plasmalogens for the correct and timely differentiation of Schwann cells and for the process of myelination. In addition, these studies identify a mechanism by which the lack of a membrane phospholipid causes neuropathology, implicating plasmalogens as regulators of membrane and cell signaling.We thank Paula Sampaio for microscopy support, Paula Magalhdes for genotyping, and Isabel Carvalho, Sofia Lamas, and Fatima Martins for excellent animal care. We are grateful to P. Brophy (University of Edinburgh) for the DRP2 antibody and to M. Baes (K.U. Leuven) for providing the Gnpat mouse strain. This work was funded by the Research Foundation of the European Leukodystrophy Association (ELA 2008-009C4, ELA 2010-042C5), by FEDER Funds through the Operational Competitiveness Program - COMPETE, and by national funds through the FCT - Fundacao para a Ciencia e a Tecnologia under the project FCOMP-01-0124-FEDER-015970 (PTDS/SAU-ORG/112406/2009). P. Brites is an FCT Investigator, and T. Ferreira da Silva was supported by the FCT (SFRH/BD/88160/2012)

Atualização no diagnóstico por imagem da miocardiopatia chagásica: uma revisão bibliográfica / Update on the imaging diagnosis of chagasic cardiomyopathy: a literature review

A Doença de Chagas é uma patologia crônica e de caráter infeccioso causada pelo protozoário flagelado Trypanosoma cruzi (T. cruzi), sendo classificada como enfermidade negligenciada pela Organização Mundial da Saúde (OMS) e apresentando elevada taxa de morbimortalidade em países endêmicos, incluindo o Brasil. Os objetivos do estudo foram analisar as atualizações radiográficas na cardiopatia chagásica, demostrando as características dos exames radiológicos mais utilizados atualmente no diagnóstico dessa enfermidade. Trata-se de uma revisão bibliográfica realizada por meio de pesquisa nos bancos de dados: EBSCO e Scielo, com os descritores “chagas cardiomyopathy”, “diagnostic imaging” entre os anos de 2014 a 2019 em língua portuguesa e inglesa. Os resultados demonstraram que o avanço tecnológico possibilitou a identificação precoce de pequenas anormalidades no miocárdio, principalmente com a metodologia de ressonância magnética. A detecção precoce do acometimento miocárdico é crucial para identificar pacientes com alto risco de insuficiência cardíaca, arritmias, eventos tromboembólicos, possibilitando intervenções para reduzir a morbimortalidade da doença