Direct Measurement of the Fermi Energy in Graphene Using a Double Layer Structure

We describe a technique which allows a direct measurement of the relative Fermi energy in an electron system using a double layer structure, where graphene is one of the two layers. We illustrate this method by probing the Fermi energy as a function of density in a graphene monolayer, at zero and in high magnetic fields. This technique allows us to determine the Fermi velocity, Landau level spacing, and Landau level broadening in graphene. We find that the N=0 Landau level broadening is larger by comparison to the broadening of upper and lower Landau levels.Comment: 5 pages, 4 figure

Anisotropic colloids through non-trivial buckling

We present a study on buckling of colloidal particles, including experimental, theoretical and numerical developments. Oil-filled thin shells prepared by emulsion templating show buckling in mixtures of water and ethanol, due to dissolution of the core in the external medium. This leads to conformations with a single depression, either axisymmetric or polygonal depending on the geometrical features of the shells. These conformations could be theoretically and/or numerically reproduced in a model of homogeneous spherical thin shells with bending and stretching elasticity, submitted to an isotropic external pressure.Comment: submitted to EPJ

Stronger diversity effects with increased environmental stress : a study of multitrophic interactions between oak, powdery mildew and ladybirds

Recent research has suggested that increasing neighbourhood tree species diversity may mitigate the impact of pests or pathogens by supporting the activities of their natural enemies and/or reducing the density of available hosts. In this study, we attempted to assess these mechanisms in a multitrophic study system of young oak (Quercus), oak powdery mildew (PM, caused by Erysiphe spp.) and a mycophagous ladybird (Psyllobora vigintiduo-punctata). We assessed ladybird mycophagy on oak PM in function of different neighbourhood tree species compositions. We also evaluated whether these species interactions were modulated by environmental conditions as suggested by the Stress Gradient Hypothesis. We adopted a complementary approach of a field experiment where we monitored oak saplings subjected to a reduced rainfall gradient in a young planted forest consisting of different tree species mixtures, as well as a lab experiment where we independently evaluated the effect of different watering treatments on PM infections and ladybird mycophagy. In the field experiment, we found effects of neighbourhood tree species richness on ladybird mycophagy becoming more positive as the target trees received less water. This effect was only found as weather conditions grew drier. In the lab experiment, we found a preference of ladybirds to graze on infected leaves from trees that received less water. We discuss potential mechanisms that might explain this preference, such as emissions of volatile leaf chemicals. Our results are in line with the expectations of the Natural Enemies Hypothesis and support the hypothesis that biodiversity effects become stronger with increased environmental stress

Movement control tests of the low back; evaluation of the difference between patients with low back pain and healthy controls

<p>Abstract</p> <p>Background</p> <p>To determine whether there is a difference between patients with low back pain and healthy controls in a test battery score for movement control of the lumbar spine.</p> <p>Methods</p> <p>This was a case control study, carried out in five outpatient physiotherapy practices in the German-speaking part of Switzerland. Twelve physiotherapists tested the ability of 210 subjects (108 patients with non-specific low back pain and 102 control subjects without back pain) to control their movements in the lumbar spine using a set of six tests. We observed the number of positive tests out of six (mean, standard deviation and 95% confidence interval of the mean). The significance of the differences between the groups was calculated with Mann-Whitney U test and <it>p </it>was set on <0.05. The effect size (d) between the groups was calculated and d>0.8 was considered a large difference.</p> <p>Results</p> <p>On average, patients with low back pain had 2.21(95%CI 1.94–2.48) positive tests and the healthy controls 0.75 (95%CI 0.55–0.95). The effect size was d = 1.18 (p < 0.001). There was a significant difference between acute and chronic (p < 0.01), as well as between subacute and chronic patient groups (p < 0.03), but not between acute and subacute patient groups (p > 0.7).</p> <p>Conclusion</p> <p>This is the first study demonstrating a significant difference between patients with low back pain and subjects without back pain regarding their ability to actively control the movements of the low back. The effect size between patients with low back pain and healthy controls in movement control is large.</p

Reliability of movement control tests in the lumbar spine

<p>Abstract</p> <p>Background</p> <p>Movement control dysfunction [MCD] reduces active control of movements. Patients with MCD might form an important subgroup among patients with non specific low back pain. The diagnosis is based on the observation of active movements. Although widely used clinically, only a few studies have been performed to determine the test reliability. The aim of this study was to determine the inter- and intra-observer reliability of movement control dysfunction tests of the lumbar spine.</p> <p>Methods</p> <p>We videoed patients performing a standardized test battery consisting of 10 active movement tests for motor control in 27 patients with non specific low back pain and 13 patients with other diagnoses but without back pain. Four physiotherapists independently rated test performances as correct or incorrect per observation, blinded to all other patient information and to each other. The study was conducted in a private physiotherapy outpatient practice in Reinach, Switzerland. Kappa coefficients, percentage agreements and confidence intervals for inter- and intra-rater results were calculated.</p> <p>Results</p> <p>The kappa values for inter-tester reliability ranged between 0.24 – 0.71. Six tests out of ten showed a substantial reliability [k > 0.6]. Intra-tester reliability was between 0.51 – 0.96, all tests but one showed substantial reliability [k > 0.6].</p> <p>Conclusion</p> <p>Physiotherapists were able to reliably rate most of the tests in this series of motor control tasks as being performed correctly or not, by viewing films of patients with and without back pain performing the task.</p

Mycorrhizas and biomass crops: opportunities for future sustainable development

Central to soil health and plant productivity in natural ecosystems are in situ soil microbial communities, of which mycorrhizal fungi are an integral component, regulating nutrient transfer between plants and the surrounding soil via extensive mycelial networks. Such networks are supported by plant-derived carbon and are likely to be enhanced under coppiced biomass plantations, a forestry practice that has been highlighted recently as a viable means of providing an alternative source of energy to fossil fuels, with potentially favourable consequences for carbon mitigation. Here, we explore ways in which biomass forestry, in conjunction with mycorrhizal fungi, can offer a more holistic approach to addressing several topical environmental issues, including ‘carbon-neutral’ energy, ecologically sustainable land management and CO2 sequestration