2D Rutherford-Like Scattering in Ballistic Nanodevices

Ballistic injection in a nanodevice is a complex process where electrons can either be transmitted or reflected, thereby introducing deviations from the otherwise quantized conductance. In this context, quantum rings (QRs) appear as model geometries: in a semiclassical view, most electrons bounce against the central QR antidot, which strongly reduces injection efficiency. Thanks to an analogy with Rutherford scattering, we show that a local partial depletion of the QR close to the edge of the antidot can counter-intuitively ease ballistic electron injection. On the contrary, local charge accumulation can focus the semi-classical trajectories on the hard-wall potential and strongly enhance reflection back to the lead. Scanning gate experiments on a ballistic QR, and simulations of the conductance of the same device are consistent, and agree to show that the effect is directly proportional to the ratio between the strength of the perturbation and the Fermi energy. Our observation surprisingly fits the simple Rutherford formalism in two-dimensions in the classical limit

Chiral nature of magnetic monopoles in artificial spin ice

Micromagnetic properties of monopoles in artificial kagome spin ice systems are investigated using numerical simulations. We show that micromagnetics brings additional complexity into the physics of these monopoles that is, by essence, absent in spin models: besides a fractionalized classical magnetic charge, monopoles in the artificial kagome ice are chiral at remanence. Our simulations predict that the chirality of these monopoles can be controlled without altering their charge state. This chirality breaks the vertex symmetry and triggers a directional motion of the monopole under an applied magnetic field. Our results also show that the choice of the geometrical features of the lattice can be used to turn on and off this chirality, thus allowing the investigation of chiral and achiral monopoles.Comment: 10 pages, 4 figure

Origin of the Universal Roughness Exponent of Brittle Fracture Surfaces: Correlated Percolation in the Damage Zone

We suggest that the observed large-scale universal roughness of brittle fracture surfaces is due to the fracture process being a correlated percolation process in a self-generated quadratic damage gradient. We use the quasi-static two-dimensional fuse model as a paradigm of a fracture model. We measure for this model, that exhibits a correlated percolation process, the correlation length exponent nu approximately equal to 1.35 and conjecture it to be equal to that of uncorrelated percolation, 4/3. We then show that the roughness exponent in the fuse model is zeta = 2 nu/(1+2 nu)= 8/11. This is in accordance with the numerical value zeta=0.75. As for three-dimensional brittle fractures, a mean-field theory gives nu=2, leading to zeta=4/5 in full accordance with the universally observed value zeta =0.80.Comment: 4 pages RevTeX

[It\u27s] more than just medicine : The value and sustainability of mandatory, non-clinical, short-term rural placements in a Western Australian medical school

Introduction: In 2005, the University of Notre Dame School of Medicine (Western Australia) established a mandatory, non-clinical rural and remote (hereafter termed rural) health placement program delivered in 2 weeks over 2 years, largely resourced by voluntary human capital. Our study investigated whether the program: (1) encouraged medical graduates to seek rural employment; (2) enhanced their ability to meet rural people’s health needs; and (3) was sustainable. Methods: A qualitative descriptive study collected data using semi-structured, in-depth interviews with graduates and placement hosts. Data were transcribed, coded and analysed using Framework Analysis to identify key themes. Results: Twenty-eight medical graduates and 15 community hosts participated. The program validated pre-existing interest in, or positively influenced graduates’ attitudes towards, rural practice, and enabled empathy and responsiveness when caring for rural patients in urban, as well as rural, health services. Placement hosts unanimously supported the program and contributed social capital, to ensure its sustainability. Discussion: The program influenced a broad spectrum of students over 15 years and reflects a socially-accountable approach to medical education. Conclusions: This study demonstrates the sustainability and value of mandatory short-term community-based placements in improving medical graduates’ responsiveness to the health needs of rural Australians

A rare infection revealed by cervicofacial masses

Digitalitzat per Artypla

Total Sulphur Content and N:S Ratio as Indicators for S Deficiency in Grasses

Recently, sulphur (S) deficiencies have been observed throughout Europe (Zaoh et al., 2002). Grassland covers about 50 % of the agricultural area in the European Union. In cutting regimes exports are ca 30 kg S/ha per year. Atmospheric depositions provide, at the present, ca15 kg S/ha per year and S is not considered in fertiliser programmes. Without fertilisation, the S balance at the field scale is negative and therefore some cut swards could be S deficient. Tools for determining whether the grassland is deficient are required. The utilisation of indicators based on S content and N:S ratio was investigated by using S deficient grasses produced in a controlled environment

Study of Soil Characteristics to Estimate Sulphur Supply for Plant Growth

During the last decades, sulphur (S) deficiencies have been observed throughout Europe (Zaoh et al., 2002). Accurate estimation of S supply by the soil-atmosphere system is required to give advice for S fertilisers. Soil is an important S source for plants and it is therefore important to evaluate supply by the soil to avoid deficiencies or excessive S fertilisation. The purpose of this preliminary study was to estimate which soil characteristics could be useful for predicting S supply by soil. Lolium multiflorum was grown on different soils in a growth chamber and S supply was correlated with soil characteristics

Portugal’s rising research in architecture and urbanism: the influence of international research centers and authors

In the early 1960s, Portugal saw a rise in scientific research on architecture and urbanism at the National Laboratory of Civil Engineering (Laboratório Nacional de Engenharia Civil; LNEC), fundamental to support the Government in establishing a national program for housing, which continued until the fall of the Dictatorship in 1974. Lacking tradition in scientific studies in architecture and urbanism, a group of young architects with knowledge of references from international researchers and research centers gathered encouragement and opportunities to develop their own research works and methodologies and, later, to question the application of such scientific methods. This article aims to identify and discuss the strategies and methodologies explored to develop these seminal researches, retrieving and reappraising LNEC’s archived documents and oral testimonials from former researchers. We aim at exposing the foundations of Portuguese scientific research on architecture and urbanism and its contributions to an international audienceinfo:eu-repo/semantics/acceptedVersio