Observing and Improving the Reliability of Internet Last-mile Links

People rely on having persistent Internet connectivity from their homes and mobile devices. However, unlike links in the core of the Internet, the links that connect people's homes and mobile devices, known as "last-mile" links, are not redundant. As a result, the reliability of any given link is of paramount concern: when last-mile links fail, people can be completely disconnected from the Internet. In addition to lacking redundancy, Internet last-mile links are vulnerable to failure. Such links can fail because the cables and equipment that make up last-mile links are exposed to the elements; for example, weather can cause tree limbs to fall on overhead cables, and flooding can destroy underground equipment. They can also fail, eventually, because cellular last-mile links can drain a smartphone's battery if an application tries to communicate when signal strength is weak. In this dissertation, I defend the following thesis: By building on existing infrastructure, it is possible to (1) observe the reliability of Internet last-mile links across different weather conditions and link types; (2) improve the energy efficiency of cellular Internet last-mile links; and (3) provide an incrementally deployable, energy-efficient Internet last-mile downlink that is highly resilient to weather-related failures. I defend this thesis by designing, implementing, and evaluating systems

Computational methods for the analysis of next generation viral sequences

Recent advances in sequencing technologies have brought a renewed impetus to the development of bioinformatics tools necessary for sequence processing and analysis. Along with the constant requirement to be able to assemble more complex genomes from ever evolving sequencing experiments and technologies there also exists a lack in visually accessible representations of information generated by analysis tools. Most of the novel algorithms, specifically for de novo genome assembly of next generation sequencing (NGS) data, are not able to efficiently handle data generated on large populations. We have assessed the common methods for genome assembly used today both from a theoretical point of view and their practical implementations. In this dissertation we present StarK (stands for k�), a novel assembly algorithm with a new data structure designed to overcome some of the limitations that we observed in established methods enabling higher quality NGS data processing. The StarK approach structurally combines de Brujin graphs for all possible dimensions in one supergraph. Although the technique to join reads remains in concept the same, the dimension k is no longer fixed. StarK is designed in such a way that it allows the assembler to dynamically adjust the de Brujin graph dimension k on the fly and at any given nucleotide position without losing connections between graph vertices or doing complicated calculations. The new graph uses localised coverage difference evaluation to create connected sub graphs which allows higher resolution of genomic differences and helps differentiate errors from potential variants within the sequencing sample. In addition to this we present a bioinformatics analysis pipeline for high-variation viral population analysis (including transmission studies), which, using both new and established methods, creates easily interpretable visual representations of the underlying data analysis. Together we provide a solid framework for biologists for extracting more information from sequencing data with less effort and faster than before

Blind packet forwarding: a clean-slate security approach for future networks

Meanwhile, there exist a wealth of approaches for a Future Network Architecture (FNA). Although these approaches differ in their orientation, they all suggest that a network should be service-oriented and flexibly orchestrated from atomic smart in-network services. In order to utilise the complete functionality of the orchestrated network, the in-network services require access to various control data that is exchanged in different ways. Hence, the communication endpoints have to expose more and more information about themselves. However, the in-network services as well as third parties are able to sniff information while it is transferred in cleartext. Beside these considerations, end-to-end encryption is the de facto method applied to provide information confidentiality for two communicating endpoints. But if the communicating endpoints perform end-to-end encryption, in-network services cannot accomplish their tasks anymore, since they cannot access the encrypted control data. Thus, it becomes impossible to fully utilise the benefits of FNA approaches. These issues indicate that it is only possible to realise one of the two goals – information confidentiality and smart in-network services – at once. But we demonstrate the feasibility to simultaneously establish smart in-network services and to provide information confidentiality by redesigning the packet forwarding service to make it operate blindly, which we call Blind Packet Forwarding (BPF). We choose this in-network service as an example because packet forwarding is one of the basic services required for most network architectures. Moreover, packet addresses act as the basis for operations performed by further in-network services. Furthermore, it was not possible so far to transfer packet addresses in end-to-end encrypted form. BPF provides confidentiality for packet addresses during transmission as well as during processing by network nodes

Proceedings of the 7th Sound and Music Computing Conference

Proceedings of the SMC2010 - 7th Sound and Music Computing Conference, July 21st - July 24th 2010

The semantics of gradation

The term 'gradation' is meant to cover a range of phenomena which for the time being I shall call quantitative evaluations regarding dimensions or features. I shall actually be looking into the principles governing the way gradation is expressed in language. The quantitative aspect of the adjectives of dimension occupies a key position which can be systematically explained and this aspect will be the crucial point of the discussion. I shall focus on the various grammatical forms of comparison: comparative, equative, superlative and some related constructions, and indications of measurement and adverbial indications of degree

Controlling Terahertz Radiation - Novel Fabrication Methods and Materials for Terahertz Components

The interaction between light and matter has been a field of research for centuries, from the days of Sir Isaac Newton in the 17th century up to today, where new effects, such as plasmonics open up new applications or the extension of the accessible electromagnetic spectrum, are still engaging scientists and engineers in this field of research. The understanding of the interaction between light, or more general: electromagnetic radiation and matter is a crucial step in the development of components which give the necessary control to gain access to the desired part of the electromagnetic spectrum. One of the less developed parts of the electromagnetic spectrum is terahertz (THz) radiation. THz radiation promises many applications, from spectroscopy for material and medical applications to communication technology. But, so far, most applications have not managed to overcome the experimental status, mostly because of missing materials and manufacturing methods suitable for the required length scales and material properties in the terahertz regime. This thesis focuses on structures for the control of THz radiation. To do so, and to overcome the natural limitations of many materials in the THz region, new materials and modern fabrication techniques are used to find new ways to overcome the shortage of readily available components for this part of the electromagnetic spectrum. As such, ceramics and polymers are used for various components, from lenses to spoof plasmonic waveguides, fabricated with a variety of techniques, including 3D printing and micro-milling. Finite-Difference Time-Domain simulations are used for the design of all structures. The ultimate goal is to demonstrate low-cost methods to produce THz components for future industrial implementation

Proof-theoretic Semantics for Intuitionistic Multiplicative Linear Logic

This work is the first exploration of proof-theoretic semantics for a substructural logic. It focuses on the base-extension semantics (B-eS) for intuitionistic multiplicative linear logic (IMLL). The starting point is a review of Sandqvist’s B-eS for intuitionistic propositional logic (IPL), for which we propose an alternative treatment of conjunction that takes the form of the generalized elimination rule for the connective. The resulting semantics is shown to be sound and complete. This motivates our main contribution, a B-eS for IMLL , in which the definitions of the logical constants all take the form of their elimination rule and for which soundness and completeness are established

Applications des structures algébriques associées aux systèmes intégrables

Cette thèse en trois parties regroupe des travaux de recherches sous la thématiques des symétries sous-jacentes aux systèmes intégrables et des structures algébriques qui les encodent. Une première partie illustre comment les fonctions spéciales que sont les polynômes orthogonaux apparaissent dans la théorie de la représentation des diverses structures algébriques associées à des symétries. La seconde partie se concentre sur une généralisation algébrique de l'opérateur de Heun classique menant à de nouvelles structures algébriques qui trouvent des applications en traitement de signal et dans l'étude des systèmes intégrables. La dernière partie concerne l'élaboration d'un cadre théorique dans le langage de la théorie de l'information algorithmique permettant de poser une définition mathématique de la notion d'émergence.This thesis in three parts groups research work under the theme of the symmetries underlying integrable systems and the algebraic structures that encodes them. A first part illustrates how orthogonal polynomials, a type of special function, appear in the representation theory of various algebraic structures associated to symmetries. The second part focuses on an algebraic generalization of the classical Heun operator that leads to new algebraic structures with applications in signal processing and in the study of integrable systems. The last part concerns the formulation of a framework in the language of algorithmic information theory the enables a mathematical definition for the notion of emergence

Explanation in typology

This volume provides an up-to-date discussion of a foundational issue that has recently taken centre stage in linguistic typology and which is relevant to the language sciences more generally: To what extent can cross-linguistic generalizations, i.e. statistical universals of linguistic structure, be explained by the diachronic sources of these structures? Everyone agrees that typological distributions are the result of complex histories, as “languages evolve into the variation states to which synchronic universals pertain” (Hawkins 1988). However, an increasingly popular line of argumentation holds that many, perhaps most, typological regularities are long-term reflections of their diachronic sources, rather than being ‘target-driven’ by overarching functional-adaptive motivations