Two-stage mixed discrete-continuous identification of radial basis function (RBF) neural models for nonlinear systems

The identification of nonlinear dynamic systems using radial basis function (RBF) neural models is studied in this paper. Given a model selection criterion, the main objective is to effectively and efficiently build a parsimonious compact neural model that generalizes well over unseen data. This is achieved by simultaneous model structure selection and optimization of the parameters over the continuous parameter space. It is a mixed-integer hard problem, and a unified analytic framework is proposed to enable an effective and efficient two-stage mixed discrete-continuous; identification procedure. This novel framework combines the advantages of an iterative discrete two-stage subset selection technique for model structure determination and the calculus-based continuous optimization of the model parameters. Computational complexity analysis and simulation studies confirm the efficacy of the proposed algorithm.

Formulation of Locally Reacting Surfaces in FDTD/K-DWM Modelling of Acoustic Spaces

In this paper, we present new methods for constructing and analysing formulations of locally reacting surfaces that can be used in finite difference time domain (FDTD) simulations of acoustic spaces. Novel FDTD formulations of frequency-independent and simple frequency-dependent impedance boundaries are proposed for 2D and 3D acoustic systems, including a full treatment of corners and boundary edges. The proposed boundary formulations are designed for virtual acoustics applications using the standard leapfrog scheme based on a rectilinear grid, and apply to FDTD as well as Kirchhoff variable digital waveguide mesh (K-DWM) methods. In addition, new analytic evaluation methods that accurately predict the reflectance of numerical boundary formulations are proposed. numerical experiments and numerical boundary analysis (NBA) are analysed in time and frequency domains in terms of the pressure wave reflectance for different angles of incidence and various impedances. The results show that the proposed boundary formulations structurally adhere well to the theoretical reflectance. In particular, both reflectance magnitude and phase are closely approximated even at high angles of incidence and low impedances. Furthermore, excellent agreement was found between the numerical boundary analysis and the experimental results, validating both as tools for researching FDTD boundary formulations.

The rhetoric of acculturation: When integration means assimilation

Viewing traditional acculturation literature through a social constructionist lens, the present paper identifies a number of limitations with this research. A discourse analytic approach to acculturation is offered as a means of addressing some of these issues. Drawing on examples taken from British print media debate surrounding the issue of faith schooling in the UK, an analysis is presented which illustrates the manner in which, though optimally positioned within acculturative moral hierarchies directed towards the legitimization of both pro- and anti-faith schooling debates, integration rhetoric often conceals the (re-)production of a more implicit assimilationism. Findings are discussed in terms of their implications for hegemonically structured acculturative power relations. This exploratory analysis provides the basis for reflection on the benefits of a discursive approach to acculturation. Moreover, the dependence of integrationist discourse on a series of socio-spatial resources is considered and, following on from Dixon and Durrheim's (2000) discursive re-conceptualization of place-identity, is taken to signify the need for a more environmentally 'grounded' approach to acculturation.

Nonlinear theory of solitary waves associated with longitudinal particle motion in lattices - Application to longitudinal grain oscillations in a dust crystal

The nonlinear aspects of longitudinal motion of interacting point masses in a lattice are revisited, with emphasis on the paradigm of charged dust grains in a dusty plasma (DP) crystal. Different types of localized excitations, predicted by nonlinear wave theories, are reviewed and conditions for their occurrence (and characteristics) in DP crystals are discussed. Making use of a general formulation, allowing for an arbitrary (e.g. the Debye electrostatic or else) analytic potential form phi(r) and arbitrarily long site-to-site range of interactions, it is shown that dust-crystals support nonlinear kink-shaped localized excitations propagating at velocities above the characteristic DP lattice sound speed v(0). Both compressive and rarefactive kink-type excitations are predicted, depending on the physical parameter values, which represent pulse- (shock-)like coherent structures for the dust grain relative displacement. Furthermore, the existence of breather-type localized oscillations, envelope-modulated wavepackets and shocks is established. The relation to previous results on atomic chains as well as to experimental results on strongly-coupled dust layers in gas discharge plasmas is discussed.

Alternative Factor Models and Heritability of the Short Leyton Obsessional Inventory-Children's Version

An alternative models framework was used to test three confirmatory factor analytic models for the Short Leyton Obsessional Inventory-Children's Version (Short LOI-CV) in a general population sample of 517 young adolescent twins (11-16 years). A one-factor model as implicit in current classification systems of Obsessive-Compulsive Disorder (OCD), a two-factor obsessions and compulsions model, and a multidimensional model corresponding to the three proposed subscales of the Short LOI-CV (labelled Obsessions/Incompleteness, Numbers/Luck and Cleanliness) were considered. The three-factor model was the only model to provide an adequate explanation of the data. Twin analyses suggested significant quantitative sex differences in heritability for both the Obsessions/Incompleteness and Numbers/Luck dimensions with these being significantly heritable in males only (heritability of 60% and 65% respectively). The correlation between the additive genetic effects for these two dimensions in males was 0.95 suggesting they largely share the same genetic risk factors.

The structure of the Beck Hopelessness Scale: A confirmatory factor analysis in UK students

The aim of this paper was to confirm the factor structure of the 20-item Beck Hopelessness Scale in a non-clinical population. Previous research has highlighted a lack of clarity in its construct validity with regards to this population.

Based on previous factor analytic findings from both clinical and non-clinical studies, 13 separate confirmatory factor models were specified and estimated using LISREL 8.72 to test the one, two and three-factor models.

Psychology and medical students at Queen's University, Belfast (n = 581) completed both the BHS and the Beck Depression Inventory (BDI).

All models showed reasonable fit, but only one, a four-item single-factor model demonstrated a nonsignificant chi-squared statistic. These four items can be used to derive a Short-Form BHS (SBHS) in which increasing scores (0-4) corresponded with increasing scores in the BDI. The four items were also drawn from all three of Beck's proposed triad, and included both positively and negatively scored items.

This study in a UK undergraduate non-clinical population suggests that the BHS best measures a one-factor model of hopelessness. It appears that a shorter four-item scale can also measure this one-factor model. (C) 2011 Elsevier Ltd. All rights reserved.

Children’s perceptions of primary science assessment in England and Wales

This study builds on and contributes to work on assessment of children in primary school, particularly in science. Previous research has examined primary science assessment from different standpoints, but no studies have speci?cally addressed children’s perspectives. This article provides additional insight into issues surrounding children’s assessment in primary school and how the assessment of science might develop in England after the science SATs (Standard Assessment Tests) were abolished in 2009. Some research suggests that primary science assessment via SATs is a major reason for the observed decline in children’s engagement with science in upper primary and lower secondary school. The analytic focus on engaging children as coresearchers to assist in the process of gathering informed views and interpreting ?ndings from a large sample of children’s views enables another contribution. The study, based on a survey of 1000 children in primary and secondary schools in England and Wales, reveals that despite being assessed under two different regimes (high-stakes national tests in England and moderated teacher assessment in Wales), children’s views of science assessment are remarkably consistent. Most appreciate the usefulness of science assessment and value frequent, non-SATs testing for monitoring/improving science progress. There was a largely negative impact, however, of science
assessment on children’s well-being, particularly due to stress. The paper demonstrates that children provide an important perspective on assessment and that including their views can improve policy-making in relation to primary science assessment.

Norberg-Schulz’ Elements of Space in Dark City

Alex Proyas' science fiction film Dark City (1998) puts forth questions about the building process of a city. The aliens in the film constantly alter each street, building and room to create the right environment for humans to dwell. The ‘strangers’ believe that they need to study humans in their spaces to understand human nature. They use bits and pieces of people's memories to reconstruct the city.

Christian Norberg-Schulz identifies four elements of space: physical, perceptual, existential and conceptual. Physical space is physical existence as it is. Perceptual space is the temporary space the user perceives. Existential space, for instance, the meaning of the concept of home, is abstract and permanent; it does not change with changing conditions. Finally, conceptual space, in his spatial philosophy, is the space concept of specialists like architects, economists and mathematicians.

This article analyses the future noir environment of Dark City from a spatial perspective. The notion of building is studied as to physical, perceptual, existential and conceptual spaces of Norberg-Schulz through concepts of home, identity, belonging, and alienation with reference to the architecture of the city.

Atom cooling using the dipole force of a single retroreflected laser beam

We present a mechanism for cooling atoms by a laser beam reflected from a single mirror. The cooling relies on the dipole force and thus in principle applies to arbitrary refractive particles including atoms, molecules, or dielectric spheres. Friction and equilibrium temperatures are derived by an analytic perturbative approach. Finally, semiclassical Monte-Carlo simulations are performed to validate the analytic results.

The Bright Side of Manufacturing–Remanufacturing Conflict in a Decentralised Closed-Loop Supply Chain

Researchers and managers broadly agree that original equipment manufacturers (OEMs), which have opportunities to produce both new and remanufactured products, are better off by centrally controlling their manufacturing and remanufacturing activities. Thus, OEMs should not remanufacture used products until the remanufacturing cost is sufficiently low to overcome the negative impact of new product cannibalisation. In this paper, we present a contrasting view of the manufacturing–remanufacturing conflict: OEMs sometimes benefit from the decentralised control mode under which they ignore the internal cannibalisation rather than the remanufacturing option. We consider a decentralised closed-loop supply chain in which one OEM can purchase new components from one supplier to produce new products and collect used products from consumers to produce remanufactured products. The key feature of our model is that the OEM can select a centralised or decentralised control mode to manage its manufacturing and remanufacturing activities before the supplier prices the new component. In a steady state period setting, we analyse the players’ optimal decisions and compare the OEM's profits under centralised and decentralised control modes. Our analytic results reveal that the decentralised control within the OEM can outperform the centralised control when the cost structure of producing new and remanufactured products satisfies certain conditions. Finally, the key findings are distilled in a conceptual framework and its managerial implications are discussed.

Three-Dimensional Dynamics of Breakout Afterburner Ion Acceleration Using High-Contrast Short-Pulse Laser and Nanoscale Targets

Breakout afterburner (BOA) laser-ion acceleration has been demonstrated for the first time in the laboratory. In the BOA, an initially solid-density target undergoes relativistically induced transparency, initiating a period of enhanced ion acceleration. First-ever kinetic simulations of the BOA in three dimensions show that the ion beam forms lobes in the direction orthogonal to laser polarization and propagation. Analytic theory presented for the electron dynamics in the laser ponderomotive field explains how azimuthal symmetry breaks even for a symmetric laser intensity profile; these results are consistent with recent experiments at the Trident laser facility. © 2011 American Physical Society.

JMJD6 is a driver of cellular proliferation and motility and a marker of poor prognosis in breast cancer

We developed an analytic strategy that correlates gene expression and clinical outcomes as a means to identify novel candidate oncogenes operative in breast cancer. This analysis, followed by functional characterization, resulted in the identification of Jumonji Domain Containing 6 (JMJD6) protein as a novel driver of oncogenic properties in breast cancer.

Analysis of Bayesian classification-based approaches for Android malware detection

Mobile malware has been growing in scale and complexity spurred by the unabated uptake of smartphones worldwide. Android is fast becoming the most popular mobile platform resulting in sharp increase in malware targeting the platform. Additionally, Android malware is evolving rapidly to evade detection by traditional signature-based scanning. Despite current detection measures in place, timely discovery of new malware is still a critical issue. This calls for novel approaches to mitigate the growing threat of zero-day Android malware. Hence, the authors develop and analyse proactive machine-learning approaches based on Bayesian classification aimed at uncovering unknown Android malware via static analysis. The study, which is based on a large malware sample set of majority of the existing families, demonstrates detection capabilities with high accuracy. Empirical results and comparative analysis are presented offering useful insight towards development of effective static-analytic Bayesian classification-based solutions for detecting unknown Android malware.

Comparison of sample preparation methods, validation of an UPLC-MS/MS procedure for the quantification of tetrodotoxin present in marine gastropods and analysis of pufferfish

Tetrodotoxin (TTX) is one of the most potent marine neurotoxins reported. The global distribution of this toxin is spreading with the European Atlantic coastline now being affected. Climate change and increasing pollution have been suggested as underlying causes for this. In the present study, two different sample preparation techniques were used to extract TTX from Trumpet shells and pufferfish samples. Both extraction procedures (accelerated solvent extraction (ASE) and a simple solvent extraction) were shown to provide good recoveries (80-92%). A UPLC-MS/MS method was developed for the analysis of TTX and validated following the guidelines contained in the Commission Decision 2002/657/EC for chemical contaminant analysis. The performance of this procedure was demonstrated to be fit for purpose. This study is the first report on the use of ASE as a mean for TTX extraction, the use of UPLC-MS/MS for TTX analysis, and the validation of this method for TTX in gastropods.

A Hamiltonian approach to simulation of acoustic systems involving nonlinear interactions

Nonlinear interactions take place in most systems that arise in music acoustics, usually as a result of player-instrument coupling. Several time-stepping methods exist for the numerical simulation of such systems. These methods generally involve the discretization of the Newtonian description of the system. However, it is not always possible to prove the stability of the resulting algorithms, especially when dealing with systems where the underlying force is a non-analytic function of the phase space variables. On the other hand, if the discretization is carried out on the Hamiltonian description of the system, it is possible to prove the stability of the derived numerical schemes. This Hamiltonian approach is applied to a series of test models of single or multiple nonlinear collisions and the energetic properties of the derived schemes are discussed. After establishing that the schemes respect the principle of conservation of energy, a nonlinear single-reed model is formulated and coupled to a digital bore, in order to synthesize clarinet-like sounds.