Spatial fluctuations in an optical parametric oscillator below threshold with an intracavity photonic crystal

We show how to control spatial quantum correlations in a multimode degenerate optical parametric oscillator type I below threshold by introducing a spatially inhomogeneous medium, such as a photonic crystal, in the plane perpendicular to light propagation. We obtain the analytical expressions for all the correlations in terms of the relevant parameters of the problem and study the number of photons, entanglement, squeezing, and twin beams. Considering different regimes and configurations we show the possibility to tune the instability thresholds as well as the quantumness of correlations by breaking the translational invariance of the system through a photonic crystal modulation.Comment: 12 pages, 7 figure

How neighbourhood governance entities are located within broader networks of governance : a cross-national comparison

This research considers how neighbourhood-based governance entities are located in broader networks of governance, by undertaking an international comparative investigation in two cities (Baltimore, Maryland in the US and Bristol in England). It uses an empirically-grounded approach to ascertain the function of such governance forms according to the way they are structured and operate. It assesses the governance context, focused at the urban level, within which these entities are located, considering the key actors and their relative power and the focus on deprived neighbourhoods versus broader strategies. This leads to consideration of how these strategies and actors shape the functions of neighbourhood governance and the implications in terms of the relative power vested at the neighbourhood level. The research demonstrates the localist and privatist nature of Baltimore's urban governance context, and the centrist and managerial nature of Bristol's. Within both networks a policy subsystem is evident with regard to neighbourhood approaches, but it is the broader governance network which determines the state and market imperatives pursued. In Baltimore and latterly in Bristol, tackling deprivation is a subservient agenda to the predominant imperative of growth. This highlights the importance of the two cities' shared neo-liberal context despite their different governmental systems. In Baltimore, neighbourhoods do not gain resource from the city-level governance network if they lack the assets this network seeks. The function of neighbourhood governance which results is self-help, as long as neighbourhoods have the capacity to do so. In Bristol, neighbourhood governance is steered by central government via its funding regimes and policy approaches. Changes in these have heralded a shift from the targeting of deprived areas via area-based initiatives' to seeking to link deprived neighbourhoods to the benefits of broader growth. Neighbourhood governance entities are being steered to adopt self-help strategies, irrespective of their capacity to do so.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Random Walks Along the Streets and Canals in Compact Cities: Spectral analysis, Dynamical Modularity, Information, and Statistical Mechanics

Different models of random walks on the dual graphs of compact urban structures are considered. Analysis of access times between streets helps to detect the city modularity. The statistical mechanics approach to the ensembles of lazy random walkers is developed. The complexity of city modularity can be measured by an information-like parameter which plays the role of an individual fingerprint of {\it Genius loci}. Global structural properties of a city can be characterized by the thermodynamical parameters calculated in the random walks problem.Comment: 44 pages, 22 figures, 2 table

A randomised controlled trial of cognitive behavioural treatment for obsessive compulsive disorder in children and adolescents

Cognitive behaviour therapy (CBT) for young people with obsessive compulsive disorder (OCD) has become the treatment of first choice. However, the literature is largely based on studies emphasising exposure and response prevention. In this study, we report on a randomised controlled trial of CBT for young people carried out in typical outpatient clinic conditions which focused on cognitions. A randomised controlled trial compares 10 sessions of manualised cognitive behavioural treatment with a 12-week waiting list for adolescents and children with OCD. Assessors were blind to treatment allocation. 21 consecutive patients with OCD aged between 9 and 18 years were recruited. The group who received treatment improved more than a comparison group who waited for 3 months. The second group was treated subsequently using the same protocol and made similar gains. In conclusion, CBT can be delivered effectively to young people with OCD in typical outpatient settings

Dynamics of supercooled liquids: density fluctuations and Mode Coupling Theory

We write equations of motion for density variables that are equivalent to Newtons equations. We then propose a set of trial equations parameterised by two unknown functions to describe the exact equations. These are chosen to best fit the exact Newtonian equations. Following established ideas, we choose to separate these trial functions into a set representing integrable motions of density waves, and a set containing all effects of non-integrability. It transpires that the static structure factor is fixed by this minimum condition to be the solution of the Yvon-Born-Green (YBG) equation. The residual interactions between density waves are explicitly isolated in their Newtonian representation and expanded by choosing the dominant objects in the phase space of the system, that can be represented by a dissipative term with memory and a random noise. This provides a mapping between deterministic and stochastic dynamics. Imposing the Fluctuation-Dissipation Theorem (FDT) allows us to calculate the memory kernel. We write exactly the expression for it, following two different routes, i.e. using explicitly Newtons equations, or instead, their implicit form, that must be projected onto density pairs, as in the development of the well-established Mode Coupling Theory (MCT). We compare these two ways of proceeding, showing the necessity to enforce a new equation of constraint for the two schemes to be consistent. Thus, while in the first `Newtonian' representation a simple gaussian approximation for the random process leads easily to the Mean Spherical Approximation (MSA) for the statics and to MCT for the dynamics of the system, in the second case higher levels of approximation are required to have a fully consistent theory

A framework for deriving semantic web services

Web service-based development represents an emerging approach for the development of distributed information systems. Web services have been mainly applied by software practitioners as a means to modularize system functionality that can be offered across a network (e.g., intranet and/or the Internet). Although web services have been predominantly developed as a technical solution for integrating software systems, there is a more business-oriented aspect that developers and enterprises need to deal with in order to benefit from the full potential of web services in an electronic market. This ‘ignored’ aspect is the representation of the semantics underlying the services themselves as well as the ‘things’ that the services manage. Currently languages like the Web Services Description Language (WSDL) provide the syntactic means to describe web services, but lack in providing a semantic underpinning. In order to harvest all the benefits of web services technology, a framework has been developed for deriving business semantics from syntactic descriptions of web services. The benefits of such a framework are two-fold. Firstly, the framework provides a way to gradually construct domain ontologies from previously defined technical services. Secondly, the framework enables the migration of syntactically defined web services toward semantic web services. The study follows a design research approach which (1) identifies the problem area and its relevance from an industrial case study and previous research, (2) develops the framework as a design artifact and (3) evaluates the application of the framework through a relevant scenario

Scattering From a Two Dimensional Array of Flux Tubes: A Study of The Validity of Mean Field Theory

Mean Field Theory has been extensively used in the study of systems of anyons in two spatial dimensions. In this paper we study the physical grounds for the validity of this approximation by considering the Quantum Mechanical scattering of a charged particle from a two dimensional array of magnetic flux tubes. The flux tubes are arranged on a regular lattice which is infinitely long in the ``$y$'' direction but which has a (small) finite number of columns in the ``$x$'' direction. Their physical size is assumed to be infinitesimally small. We develop a method for computing the scattering angle as well as the reflection and transmission coefficients to lowest order in the Aharonov--Bohm interaction. The results of our calculation are compared to the scattering of the same particle from a region of constant magnetic field whose magnitude is equal to the mean field of all the flux tubes. For an incident plane wave, the Mean Field approximation is shown to be valid provided the flux in each tube is much less than a single flux quantum. This is precisely the regime in which Mean Field Theory for anyons is expected to be valid. When the flux per tube becomes of order 1, Mean Field Theory is no longer valid.Comment: 23 pages, University of British Columbia Preprint UBCTP93-01

Integración del farmacéutico comunitario en un equipo de atención domiciliaria: estudio de costes de una experiencia piloto.

Objetivo: Estimar la carga económica que suponen los pacientes adscritos al servicio de atención domiciliaria de atención primaria y el coste que supondría incluir un farmacéutico en este equipo. Método: Estudio descriptivo prospectivo de evaluación de la carga económica del programa de atención domiciliaria. Emplazamiento: CAP Montnegre de una ABS urbana de la ciudad de Barcelona. Participantes: Pacientes adscritos al servicio de atención domiciliaria que fueron atendidos entre enero y junio de 2014 por la enfermera gestora de casos del centro. Las farmacéuticas revisaron la medicación de los pacientes para identificar problemas relacionados con la medicación y proponer intervenciones al equipo de atención domiciliaria. Mediciones principales: Revisando los historiales clínicos de los pacientes, se recogieron los costes en atención primaria, especializada, urgencias, ingresos y pruebas en 6 meses. Se estimó necesaria una visita del farmacéutico cada 6 meses para evaluar el plan de actuación. Se calcularon los costes medios para cada nivel asistencial. Resultados: Participaron 50 pacientes que generaron un coste medio total en 6 meses de 3174,5¿, siendo el 29% la atención primaria y el 66% la atención secundaria. El coste medio por paciente de la intervención farmacéutica fue de 116,4¿ (lo que supondría un incremento del 3,7% de los costes generados por estos pacientes)

Modelado de ondas no lineales en fotónica, plasmónica y átomos fríos

We review the present status of the different lines of research in the area of Photonics at the Interdisciplinary Modeling Group, InterTech (www.intertech.upv.es) paying special attention to new topics that we have recently incorporated to our research interests: temporal solitons and design of supercontinuum generation, plasmon-soliton interaction, nonlinear effects of the quantum electrodynamics vacuum, and, finally, cold atoms in the mean-field and quantum regimes.En este artículo presentamos el estado actual de las diferentes líneas de investigación desarrolladas en el área de Fotónica del Grupo de Modelización Interdisciplinar, InterTech (www.intertech.upv.es) prestando especial atención a aquellas que han sido incorporadas recientemente: solitones temporales y diseño de la generación de supercontínuo, interacción plasmón-solitón, efectos no lineales del vacío en electrodinámica cuántica y, finalmente, átomos fríos en el régimen de campo medio y en el régimen cuántico.Ciencias Experimentale