Electrical switching and interferometry of massive Dirac particles in topological insulators constrictions

We investigate the electrical switching of charge and spin transport in a topological insulator nanoconstriction in a four terminal device. The switch of the edge channels is caused by the coupling between edge states which overlap in the constriction and by the tunneling effects at the contacts and therefore can be manipulated by tuning the applied voltages on the split-gate or by geometrical etching. The switching mechanism can be conveniently studied by electron interferometry involving the measurements of the current in different configurations of the side gates, while the applied bias from the external leads can be tuned to obtain pure charge or pure spin currents (charge- and spin- bias configurations). Relevant signatures of quantum confinement effects, quantum size effects and energy gap are evident in the Fabry-Perot physics of the device allowing for a full characterization of the charge and spin currents. The proposed electrical switching behavior offers an efficient tool to manipulate topological edge state transport in a controllable way.Comment: 10 pages; 14 figure

SmokeFree Sports Project Report

Children and young people are amongst the most vulnerable groups in society and are highly susceptible to smoking experimentation and addiction. In Liverpool, smoking prevalence is significantly higher than the UK average. Therefore early intervention strategies are required for smoking prevention and cessation. Research has found a negative association between smoking and physical activity. SmokeFree Sports aims to explore whether physical activity and sport can be used to promote the smoke free message to children and young people. SmokeFree Sports is an innovative multi-dimensional campaign that incorporates social-marketing strategies alongside the provision of sports and physical activities to: a) de-normalise smoking among youth b) empower youth to stay smoke free, and c) increase awareness of the dangers of smoking using positive messaging through the medium of sport and physical activity. This project is delivered across Liverpool and aims to reduce the prevalence of smoking and prevent the uptake of smoking in children and young people. The initiative, which is managed by Liverpool John Moores University in partnership with Liverpool PCT, employs a variety of strategies to promote and deliver the smoke free message to children and young people including a) training sports coaches and teachers to deliver the smoke free message, b) delivering SFS messages in schools and youth clubs through sport and physical activity, c) asking children to sign a pledge to be smoke free, d) support voluntary sports clubs to adopt a smoke free policy on their playing fields, e) encouraging organizations and individuals interested in health and sport to sign up to the SmokeFree Sports Charter and f) signposting children to smoking cessation services

Synthesis and biological evaluation of phosphonated dihydroisoxazole nucleosides

Phosphonated isoxazolinyl nucleosides have been prepared via 1,3-dipolar cycloaddition reaction of nitrile oxides with corresponding vinyl or allyl nucleobases for antiviral studies. The cytotoxicity, the anti-HSV activity and the RT-inhibitory activity of the obtained compounds were evaluated and compared with those of AZT and diethyl{(10SR,40RS)-10-[[(5-methyl-2,4-dioxo-3,4- dihydropyrimidin-1(2H)-yl)]-30-methyl-20-oxa-30-azacyclopent-40-yl]}methylphosphonate, a saturated phosphonated dihydroisoxazole nucleoside analogue

Neural networks in geophysical applications

Neural networks are increasingly popular in geophysics. Because they are universal approximators, these tools can approximate any continuous function with an arbitrary precision. Hence, they may yield important contributions to finding solutions to a variety of geophysical applications. However, knowledge of many methods and techniques recently developed to increase the performance and to facilitate the use of neural networks does not seem to be widespread in the geophysical community. Therefore, the power of these tools has not yet been explored to their full extent. In this paper, techniques are described for faster training, better overall performance, i.e., generalization,and the automatic estimation of network size and architecture

Stellar population gradients from cosmological simulations: dependence on mass and environment in local galaxies

The age and metallicity gradients for a sample of group and cluster galaxies from N-body+hydrodynamical simulation are analyzed in terms of galaxy stellar mass. Dwarf galaxies show null age gradient with a tail of high and positive values for systems in groups and cluster outskirts. Massive systems have generally zero age gradients which turn to positive for the most massive ones. Metallicity gradients are distributed around zero in dwarf galaxies and become more negative with mass; massive galaxies have steeper negative metallicity gradients, but the trend flatten with mass. In particular, fossil groups are characterized by a tighter distribution of both age and metallicity gradients. We find a good agreement with both local observations and independent simulations. The results are also discussed in terms of the central age and metallicity, as well as the total colour, specific star formation and velocity dispersion.Comment: 9 pages, 5 figures, accepted for publication on MNRA

Teaching Teachers for the Future (TTF) Project: Development of the TTF TPACK survey instrument

This paper presents a summary of the key findings of the TTF TPACK Survey developed and administered for the Teaching the Teachers for the Future (TTF) Project implemented in 2011. The TTF Project, funded by an Australian Government ICT Innovation Fund grant, involved all 39 Australian Higher Education Institutions which provide initial teacher education. TTF data collections were undertaken at the end of Semester 1 (T1) and at the end of Semester 2 (T2) in 2011. A total of 12881 participants completed the first survey (T1) and 5809 participants completed the second survey (T2). Groups of like-named items from the T1 survey were subject to a battery of complementary data analysis techniques. The psychometric properties of the four scales: Confidence - teacher items; Usefulness - teacher items; Confidence - student items; Usefulness- student items, were confirmed both at T1 and T2. Among the key findings summarised, at the national level, the scale: Confidence to use ICT as a teacher showed measurable growth across the whole scale from T1 to T2, and the scale: Confidence to facilitate student use of ICT also showed measurable growth across the whole scale from T1 to T2. Additional key TTF TPACK Survey findings are summarised

Sex differences in exercise-induced diaphragmatic fatigue in endurance-trained athletes

There is evidence that female athletes may be more susceptible to exercise-induced arterial hypoxemia and expiratory flow limitation and have greater increases in operational lung volumes during exercise relative to men. These pulmonary limitations may ultimately lead to greater levels of diaphragmatic fatigue in women. Accordingly, the purpose of this study was to determine whether there are sex differences in the prevalence and severity of exercise-induced diaphragmatic fatigue in 38 healthy endurance-trained men (n = 19; maximal aerobic capacity = 64.0 ± 1.9 ml·kg–1·min–1) and women (n = 19; maximal aerobic capacity = 57.1 ± 1.5 ml·kg–1·min–1). Transdiaphragmatic pressure (Pdi) was calculated as the difference between gastric and esophageal pressures. Inspiratory pressure-time products of the diaphragm and esophagus were calculated as the product of breathing frequency and the Pdi and esophageal pressure time integrals, respectively. Cervical magnetic stimulation was used to measure potentiated Pdi twitches (Pdi,tw) before and 10, 30, and 60 min after a constant-load cycling test performed at 90% of peak work rate until exhaustion. Diaphragm fatigue was considered present if there was a 15% reduction in Pdi,tw after exercise. Diaphragm fatigue occurred in 11 of 19 men (58%) and 8 of 19 women (42%). The percent drop in Pdi,tw at 10, 30, and 60 min after exercise in men (n = 11) was 30.6 ± 2.3, 20.7 ± 3.2, and 13.3 ± 4.5%, respectively, whereas results in women (n = 8) were 21.0 ± 2.1, 11.6 ± 2.9, and 9.7 ± 4.2%, respectively, with sex differences occurring at 10 and 30 min (P < 0.05). Men continued to have a reduced contribution of the diaphragm to total inspiratory force output (pressure-time product of the diaphragm/pressure-time product of the esophagus) during exercise, whereas diaphragmatic contribution in women changed very little over time. The findings from this study point to a female diaphragm that is more resistant to fatigue relative to their male counterparts

Phosphonated Carbocyclic 2'-Oxa-3'-azanucleosides as New Antiretroviral Agents

Phosphonated carbocyclic 2¢-oxa-3¢-azanucleosides have been synthesized and tested for their antiretroviral activity. The obtained results have shown that some of the compounds were as powerful as azydothymidine in inhibiting the reverse transcriptase activity of the human retrovirus T-cell leukemia/lymphotropic virus type 1 and in protecting human peripheral blood mononuclear cells against human retrovirus T-cell leukemia/ lymphotropic virus type 1 transmission in vitro. These data indicate that phosphonated carbocyclic 2¢-oxa- 3¢-azanucleosides possess the necessary requirements to efficiently counteract infections caused by human retroviruses

Dynamical Generation of Spacetime Signature by Massive Quantum Fields on a Topologically Non-Trivial Background

The effective potential for a dynamical Wick field (dynamical signature) induced by the quantum effects of massive fields on a topologically non-trivial $D$ dimensional background is considered. It is shown that when the radius of the compactified dimension is very small compared with $\Lambda^{1/2}$ (where $\Lambda$ is a proper-time cutoff), a flat metric with Lorentzian signature is preferred on ${\bf R}^4 \times {\bf S}^1$. When the compactification radius becomes larger a careful analysis of the 1-loop effective potential indicates that a Lorentzian signature is preferred in both $D=6$ and $D=4$ and that these results are relatively stable under metrical perturbations