Matrix Decomposition – Analysis of an Access Control Approach on Transaction-based DAGs without Finality

The Matrix message-oriented middleware (see https://matrix.org) is gaining momentum as a basis for a decentralized, secure messaging system as shown, for example, by its deployment within the French government and by the Mozilla foundation. Thus, understanding the corresponding access control approach is important. This paper provides an ab- straction and an analysis of the access control approach followed by Matrix. We show that Matrix can be seen as a form of Distributed Ledger Technology (DLT) based on Transaction-based Directed Acyclic Graphs (TDAGs). TDAGs connect individual transactions to form a DAG, instead of collecting transactions in blocks as in blockchains. These TDAGs only provide causal order, eventual consistency, and no finality. However, unlike conventional DLTs, Matrix does not aim for a strict system-wide consensus. Thus, there is also no guarantee for a strict consensus on access rights. By de- composition of the Matrix approach, we show that a sound decen- tralized access control can be implemented for TDAGs in general, and for Matrix in particular, despite those weak guarantees. In addition, we discovered security issues in popular implementations and emphasize the need for a formal verification of the employed conflict resolution mechanism

AFRANCI : multi-layer architecture for cognitive agents

Tese de doutoramento. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 201

Stochastic epidemics in a heterogeneous community (Part III of the book Stochastic Epidemic Models and Inference)

This document is the Part III of the book 'Stochastic Epidemic Models with Inference' edited by Tom Britton and Etienne Pardoux. Plan of the chapter: 1) Random Graphs, 2) The Reproduction Number R0, 3) SIR Epidemics on Configuration Model Graphs, 4) Statistical Description of Epidemics Spreading on Networks: The Case of Cuban HIV.Comment: Lecture notes of a course given in a CIMPA school in Ziguinchor (Dec. 2015

Game-Based Learning, Gamification in Education and Serious Games

The aim of this book is to present and discuss new advances in serious games to show how they could enhance the effectiveness and outreach of education, advertising, social awareness, health, policies, etc. We present their use in structured learning activities, not only with a focus on game-based learning, but also on the use of game elements and game design techniques to gamify the learning process. The published contributions really demonstrate the wide scope of application of game-based approaches in terms of purpose, target groups, technologies and domains and one aspect they have in common is that they provide evidence of how effective serious games, game-based learning and gamification can be

Applications in Electronics Pervading Industry, Environment and Society

This book features the manuscripts accepted for the Special Issue “Applications in Electronics Pervading Industry, Environment and Society—Sensing Systems and Pervasive Intelligence” of the MDPI journal Sensors. Most of the papers come from a selection of the best papers of the 2019 edition of the “Applications in Electronics Pervading Industry, Environment and Society” (APPLEPIES) Conference, which was held in November 2019. All these papers have been significantly enhanced with novel experimental results. The papers give an overview of the trends in research and development activities concerning the pervasive application of electronics in industry, the environment, and society. The focus of these papers is on cyber physical systems (CPS), with research proposals for new sensor acquisition and ADC (analog to digital converter) methods, high-speed communication systems, cybersecurity, big data management, and data processing including emerging machine learning techniques. Physical implementation aspects are discussed as well as the trade-off found between functional performance and hardware/system costs

Constructing Orthodoxy in the Great Awakening

The Great Awakening was important as a transforming event in print culture in the British Atlantic during the end of the 1730s and early 1740s. A number of ministers collectively constructed a transatlantic correspondence network that communicated about revival-related events to each other and to a wider audience. However my study argues that outside ideological challenges were central in motivating Calvinist evangelical ministers to also utilize this network to develop a specific theology of revival. Moderate Calvinist evangelical ministers developed flexible revival orthodoxy in the Great Awakening in their print networks while in debate with other revivalists and antirevivalists. My dissertation examines what kinds of doctrines these ministers invented and how they reached agreement for what constituted normative revivalism versus what they deemed enthusiastic error. Calvinist revivalism gradually came into being around a number of loosely held ideas as ministers defended the ideas in publications with each other and in response to their opponents. The ministers experimented with how to build shared principles across denominational boundaries

Optimization and Application of Genotyping and Identification Techniques for Pneumocystis jirovecii

Pneumocystis species are obligate fungi capable of causing opportunistic infection called Pneumocystis Pneumonia (PCP) in those who are immunocompromised, often resulting in serious disease and a high mortality rate. Due to host specificity and inability to conduct in vitro studies, molecular methods have stepped in to undertake the bulk of epidemiological studies. Many unknows regarding the fungus still exist, and there is little concordance between researchers. This thesis aimed to improve and standardize the identification and genotyping techniques currently used to enable the global research community to bridge gaps collaboratively. Chapter 1 outlines Pneumocystis epidemiology, the pitfalls facing researchers and how they have been addressed. As a major influencing factor in determining sequencing success is the quality of the DNA obtained, Chapter 2 investigates and compares several DNA extraction kits and methods for an effective protocol. The gold standard for P. jirovecii currently remains to be multilocus sequence typing (MLST), therefore Chapter 3 optimizes primers and PCR protocols of the current MLST scheme used by the International Society for Human & Animal Mycology. It identified pitfalls within the scheme and addresses them by reviewing all genotyping loci and schemes used till now to determine the most effective scheme to be used in the future. This resulted in the proposal of a new global consensus MLST scheme, which was then successfully applied to a clinical cohort in Chapter 4. Chapter 5 examines the epidemiology of globally collected clinical samples using the scheme, uncovering unique alleles that formed 49 sequence types, and demonstrated the importance of a collaborative database. The importance of the genetic locus DHPS to monitor global resistance is discussed in Chapter 6. Finally, long-read next-generation sequencing using the MinION sequencer is applied to detect PCP in clinical samples to determine its potential for early diagnostics of PCP in Chapter 7