Interpreting interpolation: the pattern of interpolation errors in digital surface models derived from laser scanning data

Errors within height models have, in the past, been communicated in terms of global measures ofaccuracy for the model. Such quantification ignores the spatial structure of errors across thesurface, hindering subsequent analysis. This paper demonstrates the importance ofunderstanding the spatial structure of error using, as an example, the creation of a DigitalSurface Model (DSM) from laser scanner data

A Framework for Generalising the Newton Method and Other Iterative Methods from Euclidean Space to Manifolds

The Newton iteration is a popular method for minimising a cost function on Euclidean space. Various generalisations to cost functions defined on manifolds appear in the literature. In each case, the convergence rate of the generalised Newton iteration needed establishing from first principles. The present paper presents a framework for generalising iterative methods from Euclidean space to manifolds that ensures local convergence rates are preserved. It applies to any (memoryless) iterative method computing a coordinate independent property of a function (such as a zero or a local minimum). All possible Newton methods on manifolds are believed to come under this framework. Changes of coordinates, and not any Riemannian structure, are shown to play a natural role in lifting the Newton method to a manifold. The framework also gives new insight into the design of Newton methods in general.Comment: 36 page

Harnack Inequality and Regularity for a Product of Symmetric Stable Process and Brownian Motion

In this paper, we consider a product of a symmetric stable process in $\mathbb{R}^d$ and a one-dimensional Brownian motion in $\mathbb{R}^+$. Then we define a class of harmonic functions with respect to this product process. We show that bounded non-negative harmonic functions in the upper-half space satisfy Harnack inequality and prove that they are locally H\"older continuous. We also argue a result on Littlewood-Paley functions which are obtained by the $\alpha$-harmonic extension of an $L^p(\mathbb{R}^d)$ function.Comment: 23 page

The impact and penetration of location-based services

Since the invention of digital technology, its development has followed an entrenched path ofminiaturisation and decentralisation with increasing focus on individual and niche applications. Computerhardware has moved from remote centres to desktop and hand held devices whilst being embedded invarious material infrastructures. Software has followed the same course. The entire process has convergedon a path where various analogue devices have become digital and are increasingly being embedded inmachines at the smallest scale. In a parallel but essential development, there has been a convergence ofcomputers with communications ensuring that the delivery and interaction mechanisms for computersoftware is now focused on networks of individuals, not simply through the desktop, but in mobilecontexts. Various inert media such as fixed television is becoming more flexible as computers and visualmedia are becoming one.With such massive convergence and miniaturisation, new software and new applications define the cuttingedge. As computers are being increasingly tailored to individual niches, then new digital services areemerging, many of which represent applications which hitherto did not exist or at best were rarely focusedon a mass market. Location based services form one such application and in this paper, we will bothspeculate on and make some initial predictions of the geographical extent to which such services willpenetrate different markets. We define such services in detail below but suffice it to say at this stage thatsuch functions involve the delivery of traditional services using digital media and telecommunications.High profile applications are now being focused on hand held devices, typically involving information onproduct location and entertainment but wider applications involve fixed installations on the desktop whereservices are delivered through traditional fixed infrastructure. Both wire and wireless applications definethis domain. The market for such services is inevitably volatile and unpredictable at this early stage but wewill attempt here to provide some rudimentary estimates of what might happen in the next five to tenyears.The ?network society? which has developed through this convergence, is, according to Castells (1989,2000) changing and re-structuring the material basis of society such that information has come todominate wealth creation in a way that information is both a raw material of production and an outcome ofproduction as a tradable commodity. This has been fuelled by the way technology has expanded followingMoore?s Law and by fundamental changes in the way telecommunications, finance, insurance, utilitiesand so on is being regulated. Location based services are becoming an integral part of this fabric and thesereflect yet another convergence between geographic information systems, global positioning systems, andsatellite remote sensing. The first geographical information system, CGIS, was developed as part of theCanada Land Inventory in 1965 and the acronym ?GIS? was introduced in 1970. 1971 saw the firstcommercial satellite, LANDSAT-1. The 1970s also saw prototypes of ISDN and mobile telephone and theintroduction of TCP/IP as the dominant network protocol. The 1980s saw the IBM XT (1982) and thebeginning of de-regulation in the US, Europe and Japan of key sectors within the economy. Finally in the 1990s, we saw the introduction of the World Wide Web and the ubiquitous pervasion of business andrecreation of networked PC?s, the Internet, mobile communications and the growing use of GPS forlocational positioning and GIS for the organisation and visualisation of spatial data. By the end of the 20thcentury, the number of mobile telephone users had reached 700 million worldwide. The increasingmobility of individuals, the anticipated availability of broadband communications for mobile devices andthe growing volumes of location specific information available in databases will inevitably lead to thedemand for services that will deliver location related information to individuals on the move. Suchlocation based services (LBS) although in a very early stage of development, are likely to play anincreasingly important part in the development of social structures and business in the coming decades.In this paper we begin by defining location based services within the context we have just sketched. Wethen develop a simple model of the market for location-based services developing the standard non-linearsaturation model of market penetration. We illustrate this for mobile devices, namely mobile phones in thefollowing sections and then we develop an analysis of different geographical regimes which arecharacterised by different growth rates and income levels worldwide. This leads us to speculate on theextent to which location based services are beginning to take off and penetrate the market. We concludewith scenarios for future growth through the analogy of GIS and mobile penetration

Evaluation by simulation of interpolation and acceleration algorithms for Stepper Motors

Stepper motors are used to control CNC machines for many applications. As well as following the required path precisely, it is also important that the motion be smooth and that the surface speed be controllable. Improved interpolation algorithms for individual straight lines and circular arcs have been developed using distance as a parameter [Chow et al, 2002], [Chow, 2003]. The algorithms control the motor by means of pulses and the generation of the pulse timings is based on the geometry of the shape. For high speeds it is necessary to allow smooth acceleration at the beginning and similar smooth deceleration at the end. Thus, appropriate acceleration and deceleration algorithms have been developed for use with the new interpolation algorithms. This paper describes how simulation has been used to evaluate the new algorithms and compare them with previous algorithms. The algorithms are described for the 2D case but the principle can be extended to 3D

Ontology engineering for simulation component reuse

Commercial-off-the-shelf (COTS) simulation packages (CSPs) are widely used in industry, although they have yet to operate across organizational boundaries. Reuse across organizations is restricted by the same semantic issues that restrict the inter-organizational use of web services. The current representations of web components are predominantly syntactic in nature lacking the fundamental semantic underpinning required to support discovery on the emerging semantic web. Semantic models, in the form of ontology, utilized by web service discovery and deployment architectures provide one approach to support simulation model reuse. Semantic interoperation is achieved through the use of simulation component ontologies to identify required components at varying levels of granularity (including both abstract and specialized components). Selected simulation components are loaded into a CSP, modified according to the requirements of the new model and executed. The paper presents the development of an ontology, connector software and web service discovery architecture. The ontology is extracted from simulation scenarios involving airport, restaurant and kitchen service suppliers. The ontology engineering framework and discovery architecture provide a novel approach to inter-organizational simulation, adopting a less intrusive interface between participants. Although specific to CSPs the work has wider implications for the simulation community

Semantic web services for simulation component reuse and interoperability: An ontology approach

Commercial-off-the-shelf (COTS) Simulation Packages (CSPs) are widely used in industry primarily due to economic factors associated with developing proprietary software platforms. Regardless of their widespread use, CSPs have yet to operate across organizational boundaries. The limited reuse and interoperability of CSPs are affected by the same semantic issues that restrict the inter-organizational use of software components and web services. The current representations of Web components are predominantly syntactic in nature lacking the fundamental semantic underpinning required to support discovery on the emerging Semantic Web. The authors present new research that partially alleviates the problem of limited semantic reuse and interoperability of simulation components in CSPs. Semantic models, in the form of ontologies, utilized by the authors’ Web service discovery and deployment architecture provide one approach to support simulation model reuse. Semantic interoperation is achieved through a simulation component ontology that is used to identify required components at varying levels of granularity (i.e. including both abstract and specialized components). Selected simulation components are loaded into a CSP, modified according to the requirements of the new model and executed. The research presented here is based on the development of an ontology, connector software, and a Web service discovery architecture. The ontology is extracted from simulation scenarios involving airport, restaurant and kitchen service suppliers. The ontology engineering framework and discovery architecture provide a novel approach to inter-organizational simulation, by adopting a less intrusive interface between participants Although specific to CSPs this work has wider implications for the simulation community. The reason being that the community as a whole stands to benefit through from an increased awareness of the state-of-the-art in Software Engineering (for example, ontology-supported component discovery and reuse, and service-oriented computing), and it is expected that this will eventually lead to the development of a unique Software Engineering-inspired methodology to build simulations in future

Emotional dysfunction in schizophrenia spectrum psychosis: the role of illness perceptions

Background. Assessing illness perceptions has been useful in a range of medical disorders. This study of people with a recent relapse of their psychosis examines the relationship between illness perception, their emotional responses and their attitudes to medication.Method. One hundred patients diagnosed with a non-affective psychotic disorder were assessed within 3 months of relapse. Measures included insight, self-reported. illness perceptions, medication adherence, depression, self-esteem and anxiety.Results. Illness perceptions about psychosis explained 46, 36 and 34% of the variance in depression, anxiety and self-esteem respectively. However, self-reported medication adherence was more strongly associated with a measure of insight.Conclusions. Negative illness perceptions in psychosis are clearly related to depression, anxiety and self-esteem. These in turn have been linked to symptom maintenance and recurrence. Clinical interventions that foster appraisals of recovery rather than of chronicity and severity may therefore improve emotional well-being in people with psychosis. It might be better to address adherence to medication through direct attempts at helping them understand their need for treatment

Therapeutic advances in the treatment of vasculitis

Considerable therapeutic advances for the treatment of vasculitis of the young have been made in the past 10 years, including the development of outcome measures that facilitate clinical trial design. Notably, these include: a recognition that some patients with Kawasaki Disease require corticosteroids as primary treatment combined with IVIG; implementation of rare disease trial design for polyarteritis nodosa to deliver the first randomised controlled trial for children; first clinical trials involving children for anti-neutrophil cytoplasmic antibody (ANCA) vasculitis; and identification of monogenic forms of vasculitis that provide an understanding of pathogenesis, thus facilitating more targeted treatment. Robust randomised controlled trials for Henoch Schönlein Purpura nephritis and Takayasu arteritis are needed; there is also an over-arching need for trials examining new agents that facilitate corticosteroid sparing, of particular importance in the paediatric population since glucocorticoid toxicity is a major concern