Rendezvous on a Line by Location-Aware Robots Despite the Presence of Byzantine Faults

A set of mobile robots is placed at points of an infinite line. The robots are equipped with GPS devices and they may communicate their positions on the line to a central authority. The collection contains an unknown subset of "spies", i.e., byzantine robots, which are indistinguishable from the non-faulty ones. The set of the non-faulty robots need to rendezvous in the shortest possible time in order to perform some task, while the byzantine robots may try to delay their rendezvous for as long as possible. The problem facing a central authority is to determine trajectories for all robots so as to minimize the time until the non-faulty robots have rendezvoused. The trajectories must be determined without knowledge of which robots are faulty. Our goal is to minimize the competitive ratio between the time required to achieve the first rendezvous of the non-faulty robots and the time required for such a rendezvous to occur under the assumption that the faulty robots are known at the start. We provide a bounded competitive ratio algorithm, where the central authority is informed only of the set of initial robot positions, without knowing which ones or how many of them are faulty. When an upper bound on the number of byzantine robots is known to the central authority, we provide algorithms with better competitive ratios. In some instances we are able to show these algorithms are optimal

Proceedings of the 2015 International Conference on Distributed Computing and Networking, {ICDCN} 2015, Goa, India, January 4-7, 2015

International audienc

Creation of an Evidence-Based Implementation Framework for Digital Health Technology in the Intensive Care Unit: Qualitative Study

Background: Digital health technologies such as continuous remote monitoring and artificial intelligence–driven clinical decision support systems could improve clinical outcomes in intensive care medicine. However, comprehensive evidence and guidelines for the successful implementation of digital health technologies into specific clinical settings such as the intensive care unit (ICU) are scarce. We evaluated the implementation of a remote patient monitoring platform and derived a framework proposal for the implementation of digital health technology in an ICU. Objective: This study aims to investigate barriers and facilitators to the implementation of a remote patient monitoring technology and to develop a proposal for an implementation framework for digital health technology in the ICU. Methods: This study was conducted from May 2018 to March 2020 during the implementation of a tablet computer–based remote patient monitoring system. The system was installed in the ICU of a large German university hospital as a supplementary monitoring device. Following a hybrid qualitative approach with inductive and deductive elements, we used the Consolidated Framework for Implementation Research and the Expert Recommendations for Implementing Change to analyze the transcripts of 7 semistructured interviews with clinical ICU stakeholders and descriptive questionnaire data. The results of the qualitative analysis, together with the findings from informal meetings, field observations, and previous explorations, provided the basis for the derivation of the proposed framework. Results: This study revealed an insufficient implementation process due to lack of staff engagement and few perceived benefits from the novel solution. Further implementation barriers were the high staff presence and monitoring coverage in the ICU. The implementation framework includes strategies to be applied before and during implementation, targeting the implementation setting by involving all ICU stakeholders, assessing the intervention’s adaptability, facilitating the implementation process, and maintaining a vital feedback culture. Setting up a unit responsible for implementation, considering the guidance of an implementation advisor, and building on existing institutional capacities could improve the institutional context of implementation projects in the ICU. Conclusions: Implementation of digital health in the ICU should involve a thorough preimplementation assessment of the ICU’s need for innovation and its readiness to change, as well as an ongoing evaluation of the implementation conditions. Involvement of all stakeholders, transparent communication, and continuous feedback in an equal atmosphere are essential, but leadership roles must be clearly defined and competently filled. Our proposed framework may guide health care providers with concrete, evidence-based, and step-by-step recommendations for implementation practice, facilitating the introduction of digital health in intensive care. Trial Registration: ClinicalTrials.gov NCT03514173; https://clinicaltrials.gov/ct2/show/NCT0351417

Byzantine Agreement Decomposed: Honest Majority Asynchronous Total-Order Broadcast from Reliable Broadcast

It is well-known that Asynchronous Total Order Broadcast (ATOB) requires randomisation and that at most $t < n/3$ out of $n$ players are corrupted. This is opposed to synchronous total-order broadcast (STOB) which can tolerate $t < n/2$ corruptions and can be deterministic. We show that these requirements can be conceptually separated, by constructing an ATOB protocol which tolerates $t < n/2$ corruptions from blackbox use of Common Coin and Reliable Broadcast. We show the power of this conceptually simple contribution by reproving, using simpler protocols, existing results on STOB with optimistic responsiveness and asynchronous fallback. We also use the framework to prove the first ATOB with sub-quadratic communication and optimal corruption threshold $t < n/3$, new ATOBs with covert security and mixed adversary structures, and a new STOB with asymmetric synchrony assumptions

Efficient Communication and Synchronization on Manycore Processors

The increased number of cores integrated on a chip has brought about a number of challenges. Concerns about the scalability of cache coherence protocols have urged both researchers and practitioners to explore alternative programming models, where cache coherence is not a given. Message passing, traditionally used in distributed systems, has surfaced as an appealing alternative to shared memory, commonly used in multiprocessor systems. In this thesis, we study how basic communication and synchronization primitives on manycore processors can be improved, with an accent on taking advantage of message passing. We do this in two different contexts: (i) message passing is the only means of communication and (ii) it coexists with traditional cache-coherent shared memory. In the first part of the thesis, we analytically and experimentally study collective communication on a message-passing manycore processor. First, we devise broadcast algorithms for the Intel SCC, an experimental manycore platform without coherent caches. Our ideas are captured by OC-Bcast (on-chip broadcast), a tree-based broadcast algorithm. Two versions of OC-Bcast are presented: One for synchronous communication, suitable for use in high-performance libraries implementing the Message Passing Interface (MPI), and another for asynchronous communication, for use in distributed algorithms and general-purpose software. Both OC-Bcast flavors are based on one-sided communication and significantly outperform (by up to 3x) state-of-the-art two-sided algorithms. Next, we conceive an analytical communication model for the SCC. By expressing the latency and throughput of different broadcast algorithms through this model, we reveal that the advantage of OC-Bcast comes from greatly reducing the number of off-chip memory accesses on the critical path. The second part of the thesis focuses on lock-based synchronization. We start by introducing the concept of hybrid mutual exclusion algorithms, which rely both on cache-coherent shared memory and message passing. The hybrid algorithms we present, HybLock and HybComb, are shown to significantly outperform (by even 4x) their shared-memory-only counterparts, when used to implement concurrent counters, stacks and queues on a hybrid Tilera TILE-Gx processor. The advantage of our hybrid algorithms comes from the fact that their most critical parts rely on message passing, thereby avoiding the overhead of the cache coherence protocol. Still, we take advantage of shared memory, as shared state makes the implementation of certain mechanisms much more straightforward. Next, we try to profit from these insights even on processors without hardware support for message passing. Taking two classic x86 processors from Intel and AMD, we come up with cache-aware optimizations that improve the performance of executing contended critical sections by as much as 6x

Educational Technology and Related Education Conferences for June to December 2015

The 33rd edition of the conference list covers selected events that primarily focus on the use of technology in educational settings and on teaching, learning, and educational administration. Only listings until December 2015 are complete as dates, locations, or Internet addresses (URLs) were not available for a number of events held from January 2016 onward. In order to protect the privacy of individuals, only URLs are used in the listing as this enables readers of the list to obtain event information without submitting their e-mail addresses to anyone. A significant challenge during the assembly of this list is incomplete or conflicting information on websites and the lack of a link between conference websites from one year to the next

Crowdsourcing Crisis Management Platforms: A Privacy and Data Protection Risk Assessment and Recommendations

Over the last few years, crowdsourcing have expanded rapidly allowing citizens to connect with each other, governments to connect with common mass, to coordinate disaster response work, to map political conflicts, acquiring information quickly and participating in issues that affect day-to- day life of citizens. As emerging tools and technologies offer huge potential to response quickly and on time during crisis, crisis responders do take support from these tools and techniques. The ‘Guiding Principles’ of the Sendai Framework for Disaster Risk Reduction 2015-2030 identifies that ‘disaster risk reduction requires a multi-hazard approach and inclusive risk-informed decision-making (RIDM) based on the open exchange and dissemination of disaggregated data, including by sex, age and disability, as well as on easily accessible, up-to-date, comprehensible, science-based, non-sensitive risk information, complemented by traditional knowledge. Addressing the ‘Priority Action’ 1 & 2, this PhD research aims to identify various risks and present recommendations for ‘RIDM Process’ in form of a general Privacy and Data Protection Risk Assessment and Recommendations for crowdsourcing crisis management. It includes legal, ethical and technical recommendations