The notion of H-IFS in data modelling

In this paper we revise the context of "value imprecision", as part of an knowledge-based environment We present our approach for including value imprecision as pan of a non-rigid hierarchical structures of organization. This led us to introduce the concept of closure of an Intuitionistic fuzzy set over a universe that has a hierarchical structure. Intuitively, in the closure of this Intuitionistic fuzzy set, the "kind of" relation is taken into account by propagating the degree associated wit an element to its sub-elements in the hierarchy. We introduce the automatic analysis according to concepts defined as part of a knowledge hierarchy in order to guide the query answering as part of an integrated database environment with the aid of hierarchical intuitionistic fuzzy sets

Robust Estimators in Generalized Pareto Models

This paper deals with optimally-robust parameter estimation in generalized Pareto distributions (GPDs). These arise naturally in many situations where one is interested in the behavior of extreme events as motivated by the Pickands-Balkema-de Haan extreme value theorem (PBHT). The application we have in mind is calculation of the regulatory capital required by Basel II for a bank to cover operational risk. In this context the tail behavior of the underlying distribution is crucial. This is where extreme value theory enters, suggesting to estimate these high quantiles parameterically using, e.g. GPDs. Robust statistics in this context offers procedures bounding the influence of single observations, so provides reliable inference in the presence of moderate deviations from the distributional model assumptions, respectively from the mechanisms underlying the PBHT.Comment: 26pages, 6 figure

The distributional effects of tax and benefit reforms since 1997

Tax and benefit changes under Labour to date will have a net cost to the exchequer of around £1.1 billion in 2005–06. This is the difference between a large set of changes raising around £57.2 billion and a slightly larger set of changes costing £58.3 billion. Tax and benefit reforms implemented in Labour’s first term cost a net £4.8 billion, while those since 2001 have raised a net £3.7 billion. The average impact of the £1.1 billion tax and benefit giveaway since 1997 is to raise household disposable incomes by £0.84 a week or 0.2%. The biggest proportionate gains are in the second-poorest tenth of the population, whose disposable incomes are increased by 10.8%, while the richest tenth fare worst, with a cut in income of 5.1%. Tax and benefit reforms since 1997 have clearly been progressive, benefiting the less-well-off relative to the better-off. Reforms in the second term – while less generous on average – were more progressive than those in the first, with the poorest faring better. Increases in council tax above inflation since 1997 will raise a net £5.8 billion for local government in 2005–06, net of council tax benefit. This outweighs the £0.84 a week net giveaway per household by central government and leaves households overall £3.62 a week worse off on average. The increase in council tax is regressive, except for the poorest fifth of the population (thanks to council tax benefit). But the impact of council tax on the relative distribution of income is modest, leaving the overall progressive pattern of tax and benefit changes since 1997 intact

A geometry of information, I: Nerves, posets and differential forms

The main theme of this workshop (Dagstuhl seminar 04351) is `Spatial Representation: Continuous vs. Discrete'. Spatial representation has two contrasting but interacting aspects (i) representation of spaces' and (ii) representation by spaces. In this paper, we will examine two aspects that are common to both interpretations of the theme, namely nerve constructions and refinement. Representations change, data changes, spaces change. We will examine the possibility of a `differential geometry' of spatial representations of both types, and in the sequel give an algebra of differential forms that has the potential to handle the dynamical aspect of such a geometry. We will discuss briefly a conjectured class of spaces, generalising the Cantor set which would seem ideal as a test-bed for the set of tools we are developing.Comment: 28 pages. A version of this paper appears also on the Dagstuhl seminar portal http://drops.dagstuhl.de/portals/04351

Effect of age and cytoskeletal elements on the indentation-dependent mechanical properties of chondrocytes.

Articular cartilage chondrocytes are responsible for the synthesis, maintenance, and turnover of the extracellular matrix, metabolic processes that contribute to the mechanical properties of these cells. Here, we systematically evaluated the effect of age and cytoskeletal disruptors on the mechanical properties of chondrocytes as a function of deformation. We quantified the indentation-dependent mechanical properties of chondrocytes isolated from neonatal (1-day), adult (5-year) and geriatric (12-year) bovine knees using atomic force microscopy (AFM). We also measured the contribution of the actin and intermediate filaments to the indentation-dependent mechanical properties of chondrocytes. By integrating AFM with confocal fluorescent microscopy, we monitored cytoskeletal and biomechanical deformation in transgenic cells (GFP-vimentin and mCherry-actin) under compression. We found that the elastic modulus of chondrocytes in all age groups decreased with increased indentation (15-2000 nm). The elastic modulus of adult chondrocytes was significantly greater than neonatal cells at indentations greater than 500 nm. Viscoelastic moduli (instantaneous and equilibrium) were comparable in all age groups examined; however, the intrinsic viscosity was lower in geriatric chondrocytes than neonatal. Disrupting the actin or the intermediate filament structures altered the mechanical properties of chondrocytes by decreasing the elastic modulus and viscoelastic properties, resulting in a dramatic loss of indentation-dependent response with treatment. Actin and vimentin cytoskeletal structures were monitored using confocal fluorescent microscopy in transgenic cells treated with disruptors, and both treatments had a profound disruptive effect on the actin filaments. Here we show that disrupting the structure of intermediate filaments indirectly altered the configuration of the actin cytoskeleton. These findings underscore the importance of the cytoskeletal elements in the overall mechanical response of chondrocytes, indicating that intermediate filament integrity is key to the non-linear elastic properties of chondrocytes. This study improves our understanding of the mechanical properties of articular cartilage at the single cell level

Tax and Benefit Reforms in a Model of Labour Market Transitions. ENEPRI Research Reports No. 25, 9 October 2006

This paper presents a method for taking advantage of labour market transitions to identify the effects of financial incentives on employment decisions. The framework used is very flexible and by imposing few theoretical assumptions it allows us to extend the modelled sample relative to structural models. The authors take advantage of this flexibility to include disabled persons in the model and to jointly analyse the behaviour of disabled and non-disabled persons. A great deal of attention is paid to the appropriate modelling of financial incentives in the labour market. In the case of disabled persons, taking account of financial incentives turns out to be an extremely complex process but one that in the end turns out to be well worth the effort. The model is used to compare reactions in the labour market to marginal changes in financial incentives and also to model one of the most important reforms of the UK Labour government – the introduction of the Working Families’ Tax Credit. The methodology relies on matching the transition and income data derived from cross-sectional and panel surveys, and could be used in other countries for which detailed, reliable income data are not collected in a panel format