391 research outputs found

    Abstract Hidden Markov Models: a monadic account of quantitative information flow

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    Hidden Markov Models, HMM's, are mathematical models of Markov processes with state that is hidden, but from which information can leak. They are typically represented as 3-way joint-probability distributions. We use HMM's as denotations of probabilistic hidden-state sequential programs: for that, we recast them as `abstract' HMM's, computations in the Giry monad D\mathbb{D}, and we equip them with a partial order of increasing security. However to encode the monadic type with hiding over some state X\mathcal{X} we use DXD2X\mathbb{D}\mathcal{X}\to \mathbb{D}^2\mathcal{X} rather than the conventional XDX\mathcal{X}{\to}\mathbb{D}\mathcal{X} that suffices for Markov models whose state is not hidden. We illustrate the DXD2X\mathbb{D}\mathcal{X}\to \mathbb{D}^2\mathcal{X} construction with a small Haskell prototype. We then present uncertainty measures as a generalisation of the extant diversity of probabilistic entropies, with characteristic analytic properties for them, and show how the new entropies interact with the order of increasing security. Furthermore, we give a `backwards' uncertainty-transformer semantics for HMM's that is dual to the `forwards' abstract HMM's - it is an analogue of the duality between forwards, relational semantics and backwards, predicate-transformer semantics for imperative programs with demonic choice. Finally, we argue that, from this new denotational-semantic viewpoint, one can see that the Dalenius desideratum for statistical databases is actually an issue in compositionality. We propose a means for taking it into account

    TRADING GREEN BONDS USING DISTRIBUTED LEDGER TECHNOLOGY

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    The promising markets for voluntary carbon credits are faced with crippling challenges to the certification of carbon sequestration, and the lack of scalable market infrastructure in which institutions can invest in carbon offsetting. This amounts to a funding problem for the agricultural sector, as farmers are unable to access the liquidity needed to fund the transition to sustainable practices. We explore the feasibility of mitigating infrastructural challenges based on a DLT Trading and Settlement System, for ‘green bonds’. The artefact employs a multi-sharded architecture, in which the set of nodes retains carefully orchestrated responsibilities in the functioning of the network. We evaluate the artefact in the supranational context with an EU-based regulator as part of a regulatory sandbox program mandated by the new EU DLT Pilot regime. By conducting design-driven research with stakeholders from industrial and governmental bodies, we contribute to the IS literature on the practical implications of DLT

    Rational Financial Meltdowns

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    This article focuses on the following question: how can a group of rational, and often very sophisticated, financial actors cause financial meltdowns, in the regular course of business? There is no doubt much we still need to learn about irrational financial meltdowns, but more likely than not, cognitive shortcomings only make matters worse: they exacerbate the type of behavior that can lead even super-rational actors to cause financial meltdowns

    Principles of Security and Trust: 7th International Conference, POST 2018, Held as Part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2018, Thessaloniki, Greece, April 14-20, 2018, Proceedings

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    authentication; computer science; computer software selection and evaluation; cryptography; data privacy; formal logic; formal methods; formal specification; internet; privacy; program compilers; programming languages; security analysis; security systems; semantics; separation logic; software engineering; specifications; verification; world wide we

    The economic and ecological sustainability of the Amazonian timber industry

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    Abstract Selective logging of tropical forests, particularly reduced impact logging (RIL), has long been suggested as a benign compromise between profitable land-use and biodiversity conservation. Throughout human history, slow-renewal biological resource populations have been predictably overexploited, often to extinction. This thesis examines the degree to which timber harvests beyond the first-cut can be financially profitable or demographically sustainable, both of which remain poorly understood. Data on legally planned logging of ~17.3 million m3 of timber were obtained from 824 government-approved private and community-based concession management plans. Results indicate that neither the post-depletion timber species composition nor total value of pre-harvest forest stands recover beyond the first-cut, suggesting that commercially most valuable timber species become predictably rare or economically extinct in old logging frontiers. Additionally, smallholders appear to exert strong high-grading pressure upon high-value hardwood species, thereby accruing higher gross revenue productivity per unit area and were more likely to inconsistently report areas of unlogged forest set-asides as required by Brazilian law. Selective logging leads to several forms of collateral damage (CD) to the residual forest stand. This pattern of structural disturbance is poorly quantified or understood despite representing a key form of forest degradation, or the second ‘D’ of REDD+ (United Nations Reduced Emissions from Deforestation and Degradation). A review of studies on selective logging impacts on tropical forest fauna revealed that ~90% failed to at least report or attempt to quantify CD. This thesis also examined CD associated with a certified industrial-scale RIL operation of eastern Brazilian Amazonia and finds that for every harvested tree, there is an estimated loss of ~12 damaged stems (≥10cm DBH). Over 30% of total ground sampling area of logged forest was cleared within felled-trees impacts alone. Finally, using RIL concession data from an 11-year time series where ~0.34 million trees were harvested, we estimated the total biomass and carbon stock of harvested trees, their CD, and the infrastructure damage associated with roundlog removal. If only harvested trees and their associated CD are considered, the estimated cost incurred in sparing logging-induced forest degradation through carbon financing projects such as REDD+ could compensate for the ~393 US$ ha-1 yr-1 logging revenues accrued to concession owners

    Informacijos saugos valdymo karkasas smulkiam ir vidutiniam verslui

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    Information security is one of the concerns any organization or person faces. The list of new threats appears, and information security management mechanisms have to be established and continuously updated to be able to fight against possible security issues. To be up to date with existing information technology threats and prevention, protection, maintenance possibilities, more significant organizations establish positions or even departments, to be responsible for the information security management. However, small and medium enterprise (SME) does not have enough capacities. Therefore, the information security management situation in SMEs is fragmented and needs improvement. In this thesis, the problem of information security management in the small and medium enterprise is analyzed. It aims to simplify the information security management process in the small and medium enterprise by proposing concentrated information and tools in information security management framework. Existence of an information security framework could motivate SME to use it in practice and lead to an increase of SME security level. The dissertation consists of an introduction, four main chapters and general conclusions. The first chapter introduces the problem of information security management and its’ automation. Moreover, state-of-the-art frameworks for information security management in SME are analyzed and compared. The second chapter proposes a novel information security management framework and guidelines on its adoption. The framework is designed based on existing methodologies and frameworks. A need for a model for security evaluation based on the organization’s management structure noticed in chapter two; therefore, new probability theory-based model for organizations information flow security level estimation presented in chapter three. The fourth chapter presents the validation of proposed security evaluation models by showing results of a case study and experts ranking of the same situations. The multi-criteria analysis was executed to evaluate the ISMF suitability to be applied in a small and medium enterprise. In this chapter, we also analyze the opinion of information technology employees in an SME on newly proposed information security management framework as well as a new model for information security level estimation. The thesis is summarized by the general conclusions which confirm the need of newly proposed framework and associated tools as well as its suitability to be used in SME to increase the understanding of current information security threat situation.Dissertatio

    Fiduciary Duties and Equity-Debtholder Conflicts

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    We use an important legal event as a natural experiment to examine the effect of management fiduciary duties on equity-debt conflicts. A 1991 Delaware bankruptcy ruling changed the nature of corporate directors' fiduciary duties in firms incorporated in that state. This change limited managers' incentives to take actions favoring equity over debt for firms in the vicinity of financial distress. We show that this ruling increased the likelihood of equity issues, increased investment, and reduced firm risk, consistent with a decrease in debt-equity conflicts of interest. The changes are isolated to firms relatively closer to default. The ruling was also followed by an increase in average leverage and a reduction in covenant use. Finally, we estimate the welfare implications of this change and find that firm values increased when the rules were introduced. We conclude that managerial fiduciary duties affect equity-bond holder conflicts in a way that is economically important, has impact on ex ante capital structure choices, and affects welfare.

    Maintaining the Integrity Over Wear Time of a Hydrocolloid-based Ostomy Adhesive Whilst Maintaining Skin Barrier Function

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    In this extensive body of work, a thorough exploration delves into hydrocolloid based adhesives, with a focus on addressing challenges faced by stoma patients, particularly the susceptibility of ostomy adhesives to breakdown upon exposure to liquids. Stoma patients, compelled to wear pouching systems continuously, encounter issues like the compromise of skin barrier integrity, leading to medical adhesive-related skin injuries. The primary objective of this thesis is to reinforce the structural integrity of ostomy adhesives while preserving the skin barrier during pouching system use, an aspect often overlooked in current literature due to the hydrophilic nature of hydrocolloid based adhesives. The study introduces novel aims, examining the potential link between handedness and the preferred direction of adhesive removal, and its impact on peristomal skin complications as well as a novel skin capacitive imagery stitching technique. Another goal involves developing hierarchical structures on adhesive surfaces to enhance integrity, initial tack, and minimize skin contact for optimal skin health. The introduction provides a detailed breakdown of hydrocolloid-based ostomy adhesives, stoma anatomy, and the purpose of pouching systems. A comprehensive literature review, utilizing the PICO approach, encompasses stoma anatomy, physiology, indications for stoma surgery, and methods for assessing skin health. The review explores various methodologies to improve the durability of hydrocolloid-based adhesives, incorporating hydrodynamics, crosslinking, and layering systems. The potential influence of handedness on adhesive removal techniques is examined, considering its impact on peristomal skin complications. Results reveal the consistent performance of Welland Medical Ltd.'s hydrocolloid based adhesive but highlight the need for improved integrity over wear time. Strategies include modifying sodium-carboxymethylcellulose degree of substitution and increasing pectin degree of esterification, resulting in enhanced fluid handling capabilities and reduced susceptibility to degradation. Residual testing indicates that residual particles on the skin can impair the barrier function, remedied by a silicone-based adhesive remover. Surveys show that a patient's dominant hand and following the skin's natural langer lines during adhesive removal may minimize skin trauma. The results also show that structured surface profiles on hydrocolloid-based adhesive surfaces impact the skin's functional barrier recovery time. The research goal of this project and its objectives have been reached, the approaches have been explained clearly and implementations have been assessed using experimental findings. This project's findings contribute to advancements in ostomy care by enhancing adhesive performance, understanding patient behaviour, and improving the overall user experience. It also facilitates the efficient detachment of the adhesive from the skin surface

    Principles of Security and Trust

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    This open access book constitutes the proceedings of the 8th International Conference on Principles of Security and Trust, POST 2019, which took place in Prague, Czech Republic, in April 2019, held as part of the European Joint Conference on Theory and Practice of Software, ETAPS 2019. The 10 papers presented in this volume were carefully reviewed and selected from 27 submissions. They deal with theoretical and foundational aspects of security and trust, including on new theoretical results, practical applications of existing foundational ideas, and innovative approaches stimulated by pressing practical problems
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