2,346 research outputs found
Labour market performance of immigrants in the UK labour market
From executive summary:
This document is a report commissioned by the Home Office to analyse the performance of immigrants in the UK labour market. It attempts to draw a comprehensive picture of
the labour market performance of immigrants, and the process of adaptation relative to the UK-born white population. Four indicators of economic performance are investigated: (i) employment, (ii) labour force participation, (iii) self-employment, and (iv) wages. The
analysis distinguishes between males and females, and between groups of different origin. The effects of specific variables on these outcomes are investigated in detail. The report also considers labour market outcomes of ethnic minority individuals who are born in the UK, and compares their outcomes with those of UK-born white individuals, and of ethnic minority individuals who are foreign-born
Probabilistic latent semantic analysis as a potential method for integrating spatial data concepts
In this paper we explore the use of Probabilistic Latent Semantic Analysis (PLSA) as a method for quantifying semantic differences between land cover classes. The results are promising, revealing ‘hidden’ or not easily discernible data concepts. PLSA provides a ‘bottom up’ approach to interoperability problems for users in the face of ‘top down’ solutions provided by formal ontologies. We note the potential for a meta-problem of how to interpret the concepts and the need for further research to reconcile the top-down and bottom-up approaches
LXIV. Description of a very sensitive form of Thomson galvanometer, and some methods of galvanometer construction
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Recent advances in understanding mammalian prion structure
Prions are lethal pathogens, which cause fatal neurodegenerative diseases in mammals. They are unique infectious agents and are composed of self-propagating multi-chain assemblies of misfolded host-encoded prion protein (PrP). Understanding prion structure is fundamental to understanding prion disease pathogenesis however to date, the high-resolution structure of authentic ex vivo infectious prions remains unknown. Advances in determining prion structure have been severely impeded by the difficulty in recovering relatively homogeneous prion particles from infected brain and definitively associating infectivity with the PrP assembly state. Recently, however, images of highly infectious ex vivo PrP rods that produce prion-strain specific disease phenotypes in mice have been obtained using cryo-electron microscopy and atomic force microscopy. These images have provided the most detailed description of ex vivo mammalian prions reported to date and have established that prions isolated from multiple strains have a common hierarchical structure. Misfolded PrP is assembled into 20 nm wide rods containing two fibers, each with double helical repeating substructure, separated by a characteristic central gap 8-10 nm in width. Irregularly structured material with adhesive properties distinct to that of the fibers is present within the central gap of the rod. Prions are clearly distinguishable from non-infectious recombinant PrP fibrils generated in vitro and from all other propagating protein structures so far described in other neurodegenerative diseases. The basic architecture of mammalian prions appears to be exceptional and fundamental to their lethal pathogenicity
Study to establish cost projections for production of Redox chemicals
A cost study of four proposed manufacturing processes for redox chemicals for the NASA REDOX Energy Storage System yielded favorable selling prices in the range 1.91/kg of chromic chloride, anhydrous basis, including ferrous chloride. The prices corresponded to specific energy storage costs from under 17/kWh. A refined and expanded cost analysis of the most favored process yielded a price estimate corresponding to a storage cost of $11/kWh. The findings supported the potential economic viability of the NASA REDOX system
On the Estimation of Bivariate Return Curves for Extreme Values
In the multivariate setting, defining extremal risk measures is important in
many contexts, such as finance, environmental planning and structural
engineering. In this paper, we review the literature on extremal bivariate
return curves, a risk measure that is the natural bivariate extension to a
return level, and propose new estimation methods based on multivariate extreme
value models that can account for both asymptotic dependence and asymptotic
independence. We identify gaps in the existing literature and propose novel
tools for testing and validating return curves and comparing estimates from a
range of multivariate models. These tools are then used to compare a selection
of models through simulation and case studies. We conclude with a discussion
and list some of the challenges.Comment: 41 pages (without supplementary), 11 figures, 2 table
Improving estimation for asymptotically independent bivariate extremes via global estimators for the angular dependence function
Modelling the extremal dependence of bivariate variables is important in a
wide variety of practical applications, including environmental planning,
catastrophe modelling and hydrology. The majority of these approaches are based
on the framework of bivariate regular variation, and a wide range of literature
is available for estimating the dependence structure in this setting. However,
this framework is only applicable to variables exhibiting asymptotic
dependence, even though asymptotic independence is often observed in practice.
In this paper, we consider the so-called `angular dependence function'; this
quantity summarises the extremal dependence structure for asymptotically
independent variables. Until recently, only pointwise estimators of the angular
dependence function have been available. We introduce a range of global
estimators and compare them to another recently introduced technique for global
estimation through a systematic simulation study, and a case study on river
flow data from the north of England, UK
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