Alpha Entanglement Codes: Practical Erasure Codes to Archive Data in Unreliable Environments

Data centres that use consumer-grade disks drives and distributed peer-to-peer systems are unreliable environments to archive data without enough redundancy. Most redundancy schemes are not completely effective for providing high availability, durability and integrity in the long-term. We propose alpha entanglement codes, a mechanism that creates a virtual layer of highly interconnected storage devices to propagate redundant information across a large scale storage system. Our motivation is to design flexible and practical erasure codes with high fault-tolerance to improve data durability and availability even in catastrophic scenarios. By flexible and practical, we mean code settings that can be adapted to future requirements and practical implementations with reasonable trade-offs between security, resource usage and performance. The codes have three parameters. Alpha increases storage overhead linearly but increases the possible paths to recover data exponentially. Two other parameters increase fault-tolerance even further without the need of additional storage. As a result, an entangled storage system can provide high availability, durability and offer additional integrity: it is more difficult to modify data undetectably. We evaluate how several redundancy schemes perform in unreliable environments and show that alpha entanglement codes are flexible and practical codes. Remarkably, they excel at code locality, hence, they reduce repair costs and become less dependent on storage locations with poor availability. Our solution outperforms Reed-Solomon codes in many disaster recovery scenarios.Comment: The publication has 12 pages and 13 figures. This work was partially supported by Swiss National Science Foundation SNSF Doc.Mobility 162014, 2018 48th Annual IEEE/IFIP International Conference on Dependable Systems and Networks (DSN

Shingled Magnetic Recording disks for Mass Storage Systems

Disk drives have seen a dramatic increase in storage density over the last five decades, but to continue the growth seems difficult if not impossible because of physical limitations. One way to increase storage density is using a shingled magnetic recording (SMR) disk. Shingled writing is a promising technique that trades off the inability to update in-place for narrower tracks and thus a much higher data density. It is particularly appealing as it can be adopted while utilizing essentially the same physical recording mechanisms currently in use. Because of its manner of writing, an SMR disk would be unable to update a written track without overwriting neighboring tracks, potentially requiring the rewrite of all the tracks to the end of a band where the end of a band is an area left unwritten to allow for a non-overlapped final track. Random reads are still possible on such devices, but the handling of writes becomes particularly critical. In this manuscript, we first look at a variety of potential workloads, drawn from real-world traces, and evaluate their impact on SMR disk models. Later, we evaluate the behavior of SMR disks when used in an array configuration or when faced with heavily interleaved workloads. Specifically, we demonstrate the dramatically different effects that different workloads can have upon the opposing approaches of remapping and restoring blocks, and how write-heavy workloads can (under the right conditions, and contrary to intuition) result in a performance advantage for an SMR disk

Driven and Thermal Microparticle Rheology of Complex Biopolymer Systems

Mucociliary clearance is the process by which cilia actively transport mucus from the airway in order to keep a sterile environment in the lung. The flow properties, or the rheology, of mucus is of particular importance when considering mucus function since its modulus and viscosity result in net mucociliary transport. For example, when the protective layer of mucus is too thick, transport stops because the cilia cannot carry the increased load, as is the case in several lung-related pathologies like cystic fibrosis, COPD, and asthma. The 3DFM is an instrument we designed, implemented, and validated in our lab. Evolving significantly over the last several years, the 3DFM is a system that images and manipulates biological specimens in all three spatial dimensions at microscopic length scales. When we subject a bead embedded in a fluid to an applied force, its spatiotemporal response depends on the rheological properties of the surrounding fluid. For example, in a Newtonian fluid the terminal velocity of a bead is inversely proportional to the fluid viscosity. Applying magnetic forces to micron sized spheres or even rod-shaped particles (i.e. bacteria or magnetically permeable nanoparticles) allows us to study the correspondence (or lack thereof) between micro-physical measurements and the canonical characterizations of macroscopic rheology techniques like cone-and-plate rheometers. Also, such a microscale technique is desirable since it is often difficult to acquire sufficient volume of a purified biological sample to test using macroscale rheological techniques such as cone and plate. Biological systems can also be highly heterogeneous and present a challenge for any measurement technique because of this variability. Finally, we must mention the necessity of performing measurements at relevant length scales since evolutionary pressure is the driving force for these biopolymer systems. Here I will argue the usefulness of driven microbead rheology (DMBR) as a measurement technique for soft biopolymer solutions. I begin by explaining the effects of probe shape and make first observations regarding a preference in particle shape for drug delivery. Next, I describe the fundamental measurements in our DMBR system and offer data for well-characterized Newtonian and homogeneous viscoelastic polymer solutions. I will present experimental results and will establish the ability of DMBR as a technique for measuring both linear and nonlinear properties of non-Newtonian fluids. Finally, there will be particular attention on strain-thickening, a dynamic and nonlinear rheological property of mucus that I have observed for the first time at the microscale, making it interesting in understanding mucociliary clearance

Understanding Quantum Technologies 2022

Understanding Quantum Technologies 2022 is a creative-commons ebook that provides a unique 360 degrees overview of quantum technologies from science and technology to geopolitical and societal issues. It covers quantum physics history, quantum physics 101, gate-based quantum computing, quantum computing engineering (including quantum error corrections and quantum computing energetics), quantum computing hardware (all qubit types, including quantum annealing and quantum simulation paradigms, history, science, research, implementation and vendors), quantum enabling technologies (cryogenics, control electronics, photonics, components fabs, raw materials), quantum computing algorithms, software development tools and use cases, unconventional computing (potential alternatives to quantum and classical computing), quantum telecommunications and cryptography, quantum sensing, quantum technologies around the world, quantum technologies societal impact and even quantum fake sciences. The main audience are computer science engineers, developers and IT specialists as well as quantum scientists and students who want to acquire a global view of how quantum technologies work, and particularly quantum computing. This version is an extensive update to the 2021 edition published in October 2021.Comment: 1132 pages, 920 figures, Letter forma

Reassembling Knowledge Translation Through a Case of Autism Genomics: Multiplicity and Coordination Amidst Practiced Actor-Networks

Knowledge translation (KT) has become a ubiquitous and important component within the Canadian health research funding environment. Despite a large and burgeoning literature on the topic of KT, research on the science of KT spans a very narrow philosophical spectrum, with published studies almost exclusively positioned within positivism. Grounded in a constructionist philosophical position and influenced by actor-network theory, this dissertation aims to contribute to the Canadian KT discussion by imagining new possibilities for conceptualizing KT. This is an empirical-theoretical study which is based on eight months of data collection, including interviews, participant observation, and document analysis. This data collection took place in a basic science laboratory, a clinic, and amongst families involved in genomic research pertaining to Autism Spectrum Disorder in a Canadian city. Interviews were transcribed verbatim and organization of the data was aided by QSR Nvivo software. Theoretical insights put forward in this dissertation are based on a detailed description of the everyday, local, micro-dynamics of knowledge translation within a particular case study of an autism genomics project. Through data collection I have followed the practices of a laboratory, clinic, and family homes through which genomic knowledge was assembled and re-assembled. Through the exploration of the practices of scientists, clinicians, and families involved in an autism genetics study, I examine the concepts of multiplicity, difference, and coordination. I argue that autism is practiced differently, through different technologies and assessments, in the laboratory, clinic, and home. This dissertation closes with a new framework for and model of the knowledge translation process called the Local Translations of Knowledge in Practice model. I argue that expanding the range of theoretical and philosophical positions attended to in KT research will contribute to a richer understanding of the KT process and move forward the Canadian KT agenda. Ethics approval for this research was obtained from The University of Western Ontario and from the hospital in which the data was gathered

Spatial Formats under the Global Condition

Contributions to this volume summarize and discuss the theoretical foundations of the Collaborative Research Centre at Leipzig University which address the relationship between processes of (re-)spatialization on the one hand and the establishment and characteristics of spatial formats on the other hand

3D Recording and Interpretation for Maritime Archaeology

This open access peer-reviewed volume was inspired by the UNESCO UNITWIN Network for Underwater Archaeology International Workshop held at Flinders University, Adelaide, Australia in November 2016. Content is based on, but not limited to, the work presented at the workshop which was dedicated to 3D recording and interpretation for maritime archaeology. The volume consists of contributions from leading international experts as well as up-and-coming early career researchers from around the globe. The content of the book includes recording and analysis of maritime archaeology through emerging technologies, including both practical and theoretical contributions. Topics include photogrammetric recording, laser scanning, marine geophysical 3D survey techniques, virtual reality, 3D modelling and reconstruction, data integration and Geographic Information Systems. The principal incentive for this publication is the ongoing rapid shift in the methodologies of maritime archaeology within recent years and a marked increase in the use of 3D and digital approaches. This convergence of digital technologies such as underwater photography and photogrammetry, 3D sonar, 3D virtual reality, and 3D printing has highlighted a pressing need for these new methodologies to be considered together, both in terms of defining the state-of-the-art and for consideration of future directions. As a scholarly publication, the audience for the book includes students and researchers, as well as professionals working in various aspects of archaeology, heritage management, education, museums, and public policy. It will be of special interest to those working in the field of coastal cultural resource management and underwater archaeology but will also be of broader interest to anyone interested in archaeology and to those in other disciplines who are now engaging with 3D recording and visualization

Spatial Formats under the Global Condition

Contributions to this volume summarize and discuss the theoretical foundations of the Collaborative Research Centre at Leipzig University which address the relationship between processes of (re-)spatialization on the one hand and the establishment and characteristics of spatial formats on the other hand