Probing and modelling the localized self-mixing in a GaN/AlGaN field-effect terahertz detector

In a GaN/AlGaN field-effect terahertz detector, the directional photocurrent is mapped in the two-dimensional space of the gate voltage and the drain/source bias. It is found that not only the magnitude, but also the polarity, of the photocurrent can be tuned. A quasistatic self-mixing model taking into account the localized terahertz field provides a quantitative description of the detector characteristics. Strongly localized self-mixing is confirmed. It is therefore important to engineer the spatial distribution of the terahertz field and its coupling to the field-effect channel on the sub-micron scale.Comment: 12 pages, 4 figures, submitted to AP

Dependence of the flux creep activation energy on current density and magnetic field for MgB2 superconductor

Systematic ac susceptibility measurements have been performed on a MgB$_2$ bulk sample. We demonstrate that the flux creep activation energy is a nonlinear function of the current density $U(j)\propto j^{-0.2}$, indicating a nonlogarithmic relaxation of the current density in this material. The dependence of the activation energy on the magnetic field is determined to be a power law $U(B)\propto B^{-1.33}$, showing a steep decline in the activation energy with the magnetic field, which accounts for the steep drop in the critical current density with magnetic field that is observed in MgB$_2$. The irreversibility field is also found to be rather low, therefore, the pinning properties of this new material will need to be enhanced for practical applications.Comment: 11 pages, 6 figures, Revtex forma

Relationships between pupils’ self-perceptions, views of primary school and their development in Year 5

The Effective Pre-school and Primary Education Project 3-11 (EPPE 3-11) is a largescale longitudinal study of the impact of pre-school and primary school on children’s developmental outcomes, both cognitive and social/behavioural. The study has been following children from the start of pre-school (at age 3 years plus) through to the end of primary school. Previous reports have focused on the educational and social/behavioural outcomes of the EPPE 3-11 sample at the end of Year 5 (age 10) and progress from the end of Year 1 (age 6) to the end of Year 5 (age 10) in primary school (Sammons et al., 2007a; 2007b). The research also explored the predictive power of a wide variety of child, parent, and family characteristics on attainment and development, including the Early years home learning environment (HLE) during the years of preschool and aspects of the later HLE during Key stage 1 of primary school (Sammons et al., 2002; 2003; Sylva et al., 2004). This research builds on earlier reports (Sammons et al., 2007a; 2007b) by investigating relationships between children’s outcomes in Year 5 and aspects of pupils’ selfperceptions and their views of primary school, measured in Year 5 (age 10) and in Year 2 (age 7) of primary school, controlling for background characteristics. These measures have been derived from a self-report instrument completed by EPPE 3-11 children. The analyses explored associations between children’s progress and development over time and their self-perceptions and views of primary school

Spectral flow of monopole insertion in topological insulators

Inserting a magnetic flux into a two-dimensional one-particle Hamiltonian leads to a spectral flow through a given gap which is equal to the Chern number of the associated Fermi projection. This paper establishes a generalization to higher even dimension by inserting non-abelian monopoles of the Wu-Yang type. The associated spectral flow is then equal to a higher Chern number. For the study of odd spacial dimensions, a new so-called `chirality flow' is introduced which, for the insertion of a monopole, is then linked to higher winding numbers. This latter fact follows from a new index theorem for the spectral flow between two unitaries which are conjugates of each other by a self-adjoint unitary.Comment: title changed; final corrections before publication; to appear in Commun. Math. Phy

Influences on pupils' self-perceptions in primary school: enjoyment of school,anxiety and isolation, and self-image in year 5

This report presents the results of analyses of pupils’ self-perceptions in primary school. It is part of the longitudinal Effective Pre-school and Primary Education 3-11 (EPPE 3-11) research project funded by the Department for Children, Schools and Families (DCSF). The focus of this report is pupils’ self-perceptions in Year 5 (age 10) in four key areas: ‘Enjoyment of school’; ‘Academic self-image’; ‘Behavioural self-image’ and ‘Anxiety and Isolation’. Reports on pupils’ cognitive and social/behavioural development at this age have been published separately (Sammons et al., 2007a; 2007b). The original EPPE sample was recruited to the study at age 3 years plus and monitored to the end of Key Stage 1 (Year 2) in primary school. An additional ‘home’ sample of children (who had not attended a pre-school setting) was recruited when the pre-school sample started primary school. The EPPE 3-11 extension is following up the sample to the end of primary school (age 11 years plus). In addition to exploring pre-school influences, EPPE 3-11 research identifies the influence of primary school on a range of pupils’ educational outcomes, as well as investigating any continuing pre-school effects. EPPE 3-11 involves the collection and analysis of a range of data about pupils’ development, child, family and home learning environment (HLE) characteristics and the characteristics of the schools attended. Additional value added measures of primary school academic effectiveness have been derived from independent statistical analyses of National data sets conducted for all primary schools in England (Melhuish et al., 2006) as part of the study. These have been incorporated into the EPPE 3-11 child database to provide indicators of the academic effectiveness of primary schools attended which complement the measures on pre-school settings. Thus, it is possible to explore both preschool and primary school influences on pupils’ outcomes in Year 5. Questionnaires were administered to children asking their views about school and classroom life. These provided measures of pupils’ self-perceptions in Year 2 and again in Year 5 in terms of ‘Enjoyment of school’, ‘Anxiety and Isolation’ and ‘Academic selfimage’ and ‘Behavioural self-image’. A range of statistical methods have been used to investigate results for 2520 pupils for whom at least one self-perception outcome measure was collected in Year 5

Twisted Cyclic Cohomology and Modular Fredholm Modules

Connes and Cuntz showed in [Comm. Math. Phys. 114 (1988), 515-526] that suitable cyclic cocycles can be represented as Chern characters of finitely summable semifinite Fredholm modules. We show an analogous result in twisted cyclic cohomology using Chern characters of modular Fredholm modules. We present examples of modular Fredholm modules arising from Podle\'s spheres and from $SU_q(2)$

Importance Weighted Adversarial Nets for Partial Domain Adaptation

This paper proposes an importance weighted adversarial nets-based method for unsupervised domain adaptation, specific for partial domain adaptation where the target domain has less number of classes compared to the source domain. Previous domain adaptation methods generally assume the identical label spaces, such that reducing the distribution divergence leads to feasible knowledge transfer. However, such an assumption is no longer valid in a more realistic scenario that requires adaptation from a larger and more diverse source domain to a smaller target domain with less number of classes. This paper extends the adversarial nets-based domain adaptation and proposes a novel adversarial nets-based partial domain adaptation method to identify the source samples that are potentially from the outlier classes and, at the same time, reduce the shift of shared classes between domains

Incorporating financial literacy into the secondary school accounting curriculum: a New Zealand perspective

This paper examines whether selected stakeholder groups believe accounting should continue to be taught as an elective subject in its current form at New Zealand secondary schools or whether incorporating a financial literacy component would increase the subject’s relevance to students. A mixed method approach combining qualitative and quantitative research methods was used. An electronically administered survey was used to obtain the responses of secondary school accounting teachers, while additional insight in the form of semi-structured interviews was obtained from other stakeholders. Although respondents generally agreed that students benefited from accounting as an elective subject at secondary school, all agreed that the development of financial literacy skills was important. Difficulties in introducing a new core subject into an already overcrowded curriculum were acknowledged. However, this difficulty could be overcome by making modifications to the subject “Accounting”. As the most widespread, existing “finance” related subject, Accounting would be the most appropriate vehicle through which to teach financial literacy

Comparison of the simplified methods of the ISO 13790 standard and detailed modelling programs in a regulatory context

The CEN Standards that support the European Energy Performance of Buildings Directive requirement for calculation of the energy consumption of buildings allow various methods to be used for the same calculation. The impact of using the different methods within the updated ISO 13790 Standard for space heating and cooling energy calculations was examined with a parametric analysis of a common building specification. The impact was assessed by considering the energy band which would be assigned for the building based on the calculation results. The Standard describes three different methods that can be used for the calculations: a monthly quasi-steady state method, a simplified hourly method and detailed simulation. For most cases studied, differences in the building rating given by the various methods were a maximum of one band. More significant differences were noticed in some cases. Parameter values in the monthly method were determined which would lead to improved matching

Spectral triples for hyperbolic dynamical systems

Spectral triples are defined for C*-algebras associated with hyperbolic dynamical systems known as Smale spaces. The spectral dimension of one of these spectral triples is shown to recover the topological entropy of the Smale space