A speculative execution approach to provide semantically aware contention management for concurrent systems

PhD ThesisMost modern platforms offer ample potention for parallel execution of concurrent programs yet concurrency control is required to exploit parallelism while maintaining program correctness. Pessimistic con- currency control featuring blocking synchronization and mutual ex- clusion, has given way to transactional memory, which allows the composition of concurrent code in a manner more intuitive for the application programmer. An important component in any transactional memory technique however is the policy for resolving conflicts on shared data, commonly referred to as the contention management policy. In this thesis, a Universal Construction is described which provides contention management for software transactional memory. The technique differs from existing approaches given that multiple execution paths are explored speculatively and in parallel. In the resolution of conflicts by state space exploration, we demonstrate that both concur- rent conflicts and semantic conflicts can be solved, promoting multi- threaded program progression. We de ne a model of computation called Many Systems, which defines the execution of concurrent threads as a state space management problem. An implementation is then presented based on concepts from the model, and we extend the implementation to incorporate nested transactions. Results are provided which compare the performance of our approach with an established contention management policy, under varying degrees of concurrent and semantic conflicts. Finally, we provide performance results from a number of search strategies, when nested transactions are introduced

Serberus: Protecting Cryptographic Code from Spectres at Compile-Time

We present Serberus, the first comprehensive mitigation for hardening constant-time (CT) code against Spectre attacks (involving the PHT, BTB, RSB, STL and/or PSF speculation primitives) on existing hardware. Serberus is based on three insights. First, some hardware control-flow integrity (CFI) protections restrict transient control-flow to the extent that it may be comprehensively considered by software analyses. Second, conformance to the accepted CT code discipline permits two code patterns that are unsafe in the post-Spectre era. Third, once these code patterns are addressed, all Spectre leakage of secrets in CT programs can be attributed to one of four classes of taint primitives--instructions that can transiently assign a secret value to a publicly-typed register. We evaluate Serberus on cryptographic primitives in the OpenSSL, Libsodium, and HACL* libraries. Serberus introduces 21.3% runtime overhead on average, compared to 24.9% for the next closest state-of-the-art software mitigation, which is less secure.Comment: Authors' version; to appear in the Proceedings of the IEEE Symposium on Security and Privacy (S&P) 202

Effect of sleep on experience sampling method

Abstract. Digital data collection is practically the norm in current research. Countless studies make use of questionnaires and separate data collection methods in aim to gather scientific data from research subjects. Experience Sampling Method (ESM) collects data using stand-alone reports, very much like in traditional diary surveys. Such an approach reduces the risk of errors caused by subjects memory and reconstruction phase of past experiences. By minimising potential points of failure, data can be made more reliable. In addition, this allows data collection to be targeted at main points of the study. Purpose of the study is to explore the impact of ESM surveys on the participants, and further how the methodological questionnaires affect the surveys results. The study makes use of a mobile application used for data collection, a server connection, as well as a database for storing the results. The results did not allow drawing of direct links between ESM responses and sleep quality, albeit importance of timing of the ESM questions was identified, need of a necessary saturation of sleep data was confirmed, and an observation was made that the parameters contributing to the same metric should be placed close together timewise

The provision of humanitarian aid in complex emergencies: a case study of Somalia

This thesis examines the delivery of humanitarian assistance in Somalia at the turn of the 21st Century. Humanitarian assistance is considered as an ideal and the key question is, can it be effective in a chronic emergency? Humanitarian assistance itself is examined in detail and placed in a broader context of ideas of vulnerability, resilience and adaptive capacity in response to disasters. The thesis is grounded on evidence based evaluation to generate conclusions for programme and project management. The method taken is one of using conventional social science methods to come to evaluative judgement. The nature of evaluative judgement requires an understanding of the purpose and content of evaluation itself, which is extensively discussed in the methods chapter. The ethics of work in disaster situations is also addressed. The case material comes from two evaluations namely for Action by Churches Together and Norwegian Church Aid conducted in Somalia in 2006-07. The key findings from the case material is that humanitarian projects in chronic emergencies must be delivered within the cultural context i.e. religion supported delivery. The reasons for this are that such delivery pays attention to the critical role of beneficiaries in ensuring effective and sustainable project implementation. This raises key issues about the validity of the top down delivery of humanitarian assistance as well as an understanding of chronic emergency as development rather than disaster projects. The thesis concludes with observations on the limitations of evaluation in the context of humanitarian assistance. It reinforces the central directive of humanitarian delivery as ‘do no harm’ and shows that there are opportunities to ‘do some good’

EU Competition Litigation

All EU Member States have now transposed Directive 2014/104/EU on damages actions for breaches of competition law into national law. The Directive (and the soft-law instruments accompanying it) not only marks a new phase for private enforcement of competition law but also, more generally, provides a novel and thought provoking instance of EU harmonisation of aspects of private law and civil litigation. Following up on a previous volume in the Swedish Studies in European Law series, published in 2016, this open access book offers contributions from top practitioners and scholars from all over Europe, who present and discuss first experiences from the implementation of the new damages regime in various jurisdictions. Topics covered include theoretical and practical reflections on the state of private enforcement in Europe, the balancing of conflicting interests pertaining to public and private enforcement of competition law respectively, and specific legal issues such as causation and the estimation of harm. The authors explore problems solved, problems created, and future challenges in the new regime of private enforcement of competition law in Europe, offering predictions as to issues that may have to be settled through recourse to the European Court of Justice. The eBook editions of this book are available open access under a CC BY-NC-ND 4.0 licence on bloomsburycollections.com. Open access was funded by the Swedish Studies Network

Analyse et détection des trajectoires d'approches atypiques des aéronefs à l'aide de l'analyse de données fonctionnelles et de l'apprentissage automatique

L'amélioration de la sécurité aérienne implique généralement l'identification, la détection et la gestion des événements indésirables qui peuvent conduire à des événements finaux mortels. De précédentes études menées par la DSAC, l'autorité de surveillance française, ont permis d'identifier les approches non-conformes présentant des déviations par rapport aux procédures standards comme des événements indésirables. Cette thèse vise à explorer les techniques de l'analyse de données fonctionnelles et d'apprentissage automatique afin de fournir des algorithmes permettant la détection et l'analyse de trajectoires atypiques en approche à partir de données sol. Quatre axes de recherche sont abordés. Le premier axe vise à développer un algorithme d'analyse post-opérationnel basé sur des techniques d'analyse de données fonctionnelles et d'apprentissage non-supervisé pour la détection de comportements atypiques en approche. Le modèle sera confronté à l'analyse des bureaux de sécurité des vols des compagnies aériennes, et sera appliqué dans le contexte particulier de la période COVID-19 pour illustrer son utilisation potentielle alors que le système global ATM est confronté à une crise. Le deuxième axe de recherche s'intéresse plus particulièrement à la génération et à l'extraction d'informations à partir de données radar à l'aide de nouvelles techniques telles que l'apprentissage automatique. Ces méthodologies permettent d'améliorer la compréhension et l'analyse des trajectoires, par exemple dans le cas de l'estimation des paramètres embarqués à partir des paramètres radar. Le troisième axe, propose de nouvelles techniques de manipulation et de génération de données en utilisant le cadre de l'analyse de données fonctionnelles. Enfin, le quatrième axe se concentre sur l'extension en temps réel de l'algorithme post-opérationnel grâce à l'utilisation de techniques de contrôle optimal, donnant des pistes vers de nouveaux systèmes d'alerte permettant une meilleure conscience de la situation.Improving aviation safety generally involves identifying, detecting and managing undesirable events that can lead to final events with fatalities. Previous studies conducted by the French National Supervisory Authority have led to the identification of non-compliant approaches presenting deviation from standard procedures as undesirable events. This thesis aims to explore functional data analysis and machine learning techniques in order to provide algorithms for the detection and analysis of atypical trajectories in approach from ground side. Four research directions are being investigated. The first axis aims to develop a post-op analysis algorithm based on functional data analysis techniques and unsupervised learning for the detection of atypical behaviours in approach. The model is confronted with the analysis of airline flight safety offices, and is applied in the particular context of the COVID-19 crisis to illustrate its potential use while the global ATM system is facing a standstill. The second axis of research addresses the generation and extraction of information from radar data using new techniques such as Machine Learning. These methodologies allow to \mbox{improve} the understanding and the analysis of trajectories, for example in the case of the estimation of on-board parameters from radar parameters. The third axis proposes novel data manipulation and generation techniques using the functional data analysis framework. Finally, the fourth axis focuses on extending the post-operational algorithm into real time with the use of optimal control techniques, giving directions to new situation awareness alerting systems

Revisiting the role of the public interest in merger control

In the light of advances in economic theory and harmonisation initiatives, most jurisdictions now adopt a competition effects-based approach to merger control assessments. Given the emphasis that these assessments now afford to competition criteria, it might be said that the influence of wider ‘public interest’ considerations has become increasingly marginalised. Nevertheless, despite this marginalisation, most domestic merger regimes continue to reserve a role for public interest criteria, albeit a very restricted one in most cases. This has fuelled an on-going debate regarding the wisdom and legitimacy of considering public interest criteria in the merger assessment process. One argument, often cited by competition purists, is that pursuing a strict adherence to competition principles will deliver optimal long-term benefits for both consumers and the public at large. The main counter-argument has centred on the perceived inability of competition to respond to short-term public interest concerns which, if left unaddressed, may have lasting implications on fundamental interests such as employment, public health and democracy. Important questions therefore transpire: Is merger control an appropriate realm in which to address public interest concerns, or can these be dealt with more effectively via alternative policy means? If it is appropriate, how should public interest criteria be framed within the merger control legislation, and who should be tasked with applying this criteria? This thesis adopts legal and empirical research methods to scrutinise the role that states have afforded to the public interest in modern-day merger control. By drawing insights from merger regimes across the world, the thesis proposes a framework for accommodating public interest criteria effectively within merger control