Identifying Critical Components During information Security Evaluations

Electronic communications devices intended for government or military applications must be rigorously evaluated to ensure that they maintain data confidentiality. High-grade information security evaluations require a detailed analysis of the device’s design, to determine how it achieves necessary security functions. In practice, such evaluations are labour-intensive and costly, so there is a strong incentive to find ways to make the process more efficient. In this paper we show how well-known concepts from graph theory can be applied to a device’s design to optimise information security evaluations. In particular, we use end-to-end graph traversals to eliminate components that do not need to be evaluated at all, and minimal cutsets to identify the smallest group of components that needs to be evaluated in depth

Resolvent at low energy and Riesz transform for Schrodinger operators on asymptotically conic manifolds, I

We analyze the resolvent $R(k)=(P+k^2)^{-1}$ of Schr\"odinger operators $P=\Delta+V$ with short range potential $V$ on asymptotically conic manifolds $(M,g)$ (this setting includes asymptotically Euclidean manifolds) near $k=0$. We make the assumption that the dimension is greater or equal to 3 and that $P$ has no $L^2$ null space and no resonance at 0. In particular, we show that the Schwartz kernel of $R(k)$ is a conormal polyhomogeneous distribution on a desingularized version of $M\times M\times [0,1]$. Using this, we show that the Riesz transform of $P$ is bounded on $L^p$ for $1<p<n$ and that this range is optimal if $V$ is not identically zero or if $M$ has more than one end. We also analyze the case V=0 with one end. In a follow-up paper, we shall deal with the same problem in the presence of zero modes and zero-resonances.Comment: 28 pages, 1 figur

Numerical simulation of the airflow–rivulet interaction associated with the rain-wind induced vibration phenomenon

Rain-wind induced vibration is an aeroelastic phenomenon that occurs on the inclined cables of cable-stayed bridges. The vibrations are believed to be caused by a complicated nonlinear interaction between rivulets of rain water that run down the cables and the wind loading on the cables due to the unsteady aerodynamic flow field. Recent research at the University of Strathclyde has been to develop a numerical method to simulate the influence of the external air flow on the rivulet dynamics and vice versa, the results of which can be used to assess the importance of the water rivulets on the instability. The numerical approach for the first time couples a Discrete Vortex Method solver to determine the external flow field and unsteady aerodynamic loading, and a pseudo-spectral solver based on lubrication theory to model the evolution and growth of the water rivulets on the cable surface under external loading. The results of the coupled model are used to assess the effects of various loading combinations, and importantly are consistent with previous full scale and experimental observations of rain-wind induced vibration, providing new information about the underlying physical mechanisms of the instability

Effects of closed immersion filtered water flow velocity on the ablation threshold of bisphenol A polycarbonate during excimer laser machining

A closed flowing thick film filtered water immersion technique ensures a controlled geometry for both the optical interfaces of the flowing liquid film and allows repeatable control of flow-rate during machining. This has the action of preventing splashing, ensures repeatable machining conditions and allows control of liquid flow velocity. To investigate the impact of this technique on ablation threshold, bisphenol A polycarbonate samples have been machined using KrF excimer laser radiation passing through a medium of filtered water flowing at a number of flow velocities, that are controllable by modifying the liquid flow rates. An average decrease in ablation threshold of 7.5% when using turbulent flow velocity regime closed thick film filtered water immersed ablation, compared to ablation using a similar beam in ambient air; however, the use of laminar flow velocities resulted in negligible differences between closed flowing thick film filtered water immersion and ambient air. Plotting the recorded threshold fluence achieved with varying flow velocity showed that an optimum flow velocity of 3.00 m/s existed which yeilded a minimum ablation threshold of 112 mJ/cm2. This is attributed to the distortion of the ablation plume effected by the flowing immersion fluid changing the ablation mechanism: at laminar flow velocities Bremsstrahlung attenuation decreases etch rate, at excessive flow velocities the plume is completely destroyed, removing the effect of plume etching. Laminar flow velocity regime ablation is limited by slow removal of debris causing a non-linear etch rate over ‘n’ pulses which is a result of debris produced by one pulse remaining suspended over the feature for the next pulse. The impact of closed thick film filtered water immersed ablation is dependant upon beam fluence: high fluence beams achieved greater etch efficiency at high flow velocities as the effect of Bremsstrahlung attenuation is removed by the action of the fluid on the plume; low fluences loose efficiency as the beam makes proportionally large fluence losses at it passes through the chamber window and immersion medium

Strichartz estimates without loss on manifolds with hyperbolic trapped geodesics

Doi proved that the $L^2_t H^{1/2}_x$ local smoothing effect for Schr\"odinger equation on a Riemannian manifold does not hold if the geodesic flow has one trapped trajectory. We show in contrast that Strichartz estimates and $L^1\to L^\infty$ dispersive estimates still hold without loss for $e^{it\Delta}$ in various situations where the trapped set is hyperbolic and of sufficiently small fractal dimension.Comment: 23 pages. Corrections in the proof of prop 3.

The Distribution of plasma and other cells containing immunoglobin in the respiratory tract of normal man, and the alterations found in subjects with chronic bronchitis

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INSTITUTIONAL DIMENSIONS OF TRADE LIBERALISATION AND POVERTY

Trade policy liberalisation requires institutional change, in the sense of a change in the rules of the game. The question is whether these changes produce "superior institutions" judged in terms of a reduction of transactions costs; improved coordination; stronger strategic commitment to investing in needed specific assets; and allocative efficiency. In conventional approaches to the analysis of liberalisation, changed institutional arrangements are studied, but they tend to be considered in the category of "practical details": important but not especially intellectually interesting. In contrast, this paper argues for a parallel approach to the study of the effects of liberalisation on the rural poor, in which institutional matters are central. A broad range of institutional issues is considered, informed by a theoretical framework provided by the various strands within institutional economics. The framework set out and discussed leads to the contention that smallholder agriculture in poor countries needs coordinated market economy (CME) type institutions if it is to develop, at least at the earlier stages. Ideally, these would be based on deliberative institutions, working horizontally inside a sector, and also vertically along the supply chain. It is argued that the way forward is likely to involve a rethinking of the role of the state (at sub-national, national and international - aid donor - levels) and of the roles of producer organisations and other stakeholder (including trader) associations. The aim must be to find a way in which the state and other powerful actors can initiate deliberative processes and take a lead in encouraging appropriate asset specific investments, while at the same time planning to fade into the background as initial success is achieved. These conclusions challenge conventional analysis of trade policy liberalisation in poor countries and also challenge institutional specialists to provide insights, ideally quantifiable, into the consequences of those liberalisation policies which drive changes in such features as "non-standard institutional arrangements"; non-market coordination; and the roles of government.Food Security and Poverty, International Relations/Trade,

Market and Coordination Failures in Poor Rural Economies: Policy Implications for Agricultural and Rural Development

This paper argues that the disappointing outcomes of adjustment policies in poor rural economies, principally in sub-Saharan Africa, can be partly attributed to weaknesses in the neo-classical theory which underlies these polices and from associated failures to recognise structural changes (or transitions) in growing agricultural economies. After a brief description of agricultural policy changes in sub Saharan Africa, the mixed achievements of market liberalisation policies are explained using new institutional economic arguments regarding inherent difficulties in economic coordination in poor economies, difficulties which markets themselves cannot overcome. A novel framework is put forward for understanding coordination failure and integrating it with other causes of under-development notably low levels of technical and institutional development and poor governance. The paper concludes by considering the implications of these arguments for development policies in different sub-Saharan economies.development, coordination, markets, institutions, Marketing, O12, O17, Q12,