Dynamics of zonal flow-like structures in the edge of the TJ-II stellarator

The dynamics of fluctuating electric field structures in the edge of the TJ-II stellarator, that display zonal flow-like traits, is studied. These structures have been shown to be global and affect particle transport dynamically [J.A. Alonso et al., Nucl. Fus. 52 063010 (2012)]. In this article we discuss possible drive (Reynolds stress) and damping (Neoclassical viscosity, geodesic transfer) mechanisms for the associated ExB velocity. We show that: (a) while the observed turbulence-driven forces can provide the necessary perpendicular acceleration, a causal relation could not be firmly established, possibly because of the locality of the Reynolds stress measurements, (b) the calculated neoclassical viscosity and damping times are comparable to the observed zonal flow relaxation times, and (c) although an accompanying density modulation is observed to be associated to the zonal flow, it is not consistent with the excitation of pressure side-bands, like those present in geodesic acoustic oscillations, caused by the compression of the ExB flow field

Minimum Conductivity and Evidence for Phase Transitions in Ultra-clean Bilayer Graphene

Bilayer graphene (BLG) at the charge neutrality point (CNP) is strongly susceptible to electronic interactions, and expected to undergo a phase transition into a state with spontaneous broken symmetries. By systematically investigating a large number of singly- and doubly-gated bilayer graphene (BLG) devices, we show that an insulating state appears only in devices with high mobility and low extrinsic doping. This insulating state has an associated transition temperature Tc~5K and an energy gap of ~3 meV, thus strongly suggesting a gapped broken symmetry state that is destroyed by very weak disorder. The transition to the intrinsic broken symmetry state can be tuned by disorder, out-of-plane electric field, or carrier density

New results for a photon-photon collider

We present new results from studies in progress on physics at a two-photon collider. We report on the sensitivity to top squark parameters of MSSM Higgs boson production in two-photon collisions; Higgs boson decay to two photons; radion production in models of warped extra dimensions; chargino pair production; sensitivity to the trilinear Higgs boson coupling; charged Higgs boson pair production; and we discuss the backgrounds produced by resolved photon-photon interactions.Comment: 17 pages, 15 figure

Electrical Transport in High Quality Graphene pnp Junctions

We fabricate and investigate high quality graphene devices with contactless, suspended top gates, and demonstrate formation of graphene pnp junctions with tunable polarity and doping levels. The device resistance displays distinct oscillations in the npn regime, arising from the Fabry-Perot interference of holes between the two pn interfaces. At high magnetic fields, we observe well-defined quantum Hall plateaus, which can be satisfactorily fit to theoretical calculations based on the aspect ratio of the device.Comment: to appear in a special focus issue in New Journal of Physic

Poseidon Linux 3.x - The scientific GNU/Linux option

This software review is about the newest version of Poseidon Linux (3.x). The current Poseidon Linux is a remastering from Ubuntu LTS family (Long Term Support), with extra specific software applicable to many areas of scientific research and education. It contains specialist software for GIS/Mapping, bathymetry, numerical modeling, 2D/3D/4D visualization, bioinformatics, chemistry, statistics, as well as tools for creating simple and complex graphics and programming languages. It also includes basic packages as would be expected on a normal desktop, such as a complete office suite, internet browser, e-mail client, instant messaging, chat, multimedia and many other tools. Poseidon Linux can run in two modes, as a live-DVD or installed on the hard disk. There are versions for 32 and 64 bit computers, and support for Brazilian Portuguese, English, Spanish, French, Greek, Italian and German languages. Resumo. Poseidon Linux 3.x – A opção científica GNU/Linux. Esta resenha trata da nova versão do software Poseidon Linux (3.x). A versão atual é uma remasterização a partir do sistema operacional Ubuntu, família LTS (Suporte de Longo Prazo), com pacotes extras para várias áreas da ciência e educação. Contém programas específicos para SIG/mapeamento, batimetria, modelagem numérica, visualização 2D/3D/4D, bioinformática, química, estatística, bem como ferramentas para elaboração de gráficos simples e complexos e linguagem de programação. Inclui também os programas necessários encontrados num sistema operacional desktop, tais como suporte completo para escritório, navegador de internet, programas para envio e recebimento de mensagens instantâneas, multimídia e várias outras ferramentas. O Poseidon Linux pode ser utilizado de duas formas: diretamente do DVD, sem instalá-lo, ou instalando-o no disco rígido do computador. É apresentado nas versões 32 e 64 bits e pode ser totalmente configurado em Português do Brasil, Inglês, Espanhol, Francês, Grego, Italiano e Alemão

Suspension and Measurement of Graphene and Bi2Se3 Atomic Membranes

Coupling high quality, suspended atomic membranes to specialized electrodes enables investigation of many novel phenomena, such as spin or Cooper pair transport in these two dimensional systems. However, many electrode materials are not stable in acids that are used to dissolve underlying substrates. Here we present a versatile and powerful multi-level lithographical technique to suspend atomic membranes, which can be applied to the vast majority of substrate, membrane and electrode materials. Using this technique, we fabricated suspended graphene devices with Al electrodes and mobility of 5500 cm^2/Vs. We also demonstrate, for the first time, fabrication and measurement of a free-standing thin Bi2Se3 membrane, which has low contact resistance to electrodes and a mobility of >~500 cm^2/Vs

Comparison between Poaceae Airborne Pollen Counts and Phl p5 Aeroallergen Quantification in South Europe

The European project HIALINE: Comparison between Poaceae Airborne Pollen Counts and Phl p5 Aeroallergen Quantification in South Europe C. Antunes1,2, R. Ferro2, R. Ribeiro2, Torres M.C.4, M.J. Velasco4H. García-Mozo4, Galán, C4 , R.Brandao1,3, M.Thibaudon5, R. Albertini6 Ugolotti. M.6, Usberti I.6, Dall’Aglio P.6 and the HIALINE team7 1DInstitute of Mediterranean Agricultural and Environmental Sciences –ICAAM, University of Évora, Portugal 2Department of Chemistry, University of Évora, Portugal 3Department of Biology, University of Évora, Portugal 4Department of Botany, Ecology and Plant Physiology, University of Córdoba 5Réseau National de l Surveillance Aerobiologique, Saint-Genis-l’Argentière, France 6Department of Clinical Medicine, Nephrology and Health Sciences, University of Parma, Italy 7J.T.M. Buters, Germany, M. Thibaudon, France, M. Smith, Great Britain, C. Galan, Spain, R. Brandao and C.M. Antunes, Portugal, G. Reese, Germany, R. Albertini, Italy, L. Grewling, Poland, A. Rantio-Lehtimäki, Finland, S. Jäger and U. Berger, Austria, I. Sauliene, Lithuania, L. Cecchi, Italy Introduction: Nowadays, pollinosis is affecting a large percentage of population in countries with a western life style. The existence of allergenic activity in the atmosphere is not only associated to pollen grains and fungal spores, but also to submicronic and paucimicronic biological particles. The origin of these allergens can be due to the rupture of pollen transported in the atmosphere or to the presence of allergens from other parts of the plant making amorphous material with an allergen load. Poaceae pollen is recognized as one of the main causes of allergic disease in all Europe. In this study we have tried to compare Poaceae pollen counts in the air and Phl p 5, one of the major allergens of this family, through the use of a high-volume cascade impactor (Chemvol). This study was done in the frame of the European project HIALINE and it compares the results obtained in 2009 by 4 different partners participating in this project: in Córdoba (Spain), Évora (Portugal), Lyon (France) and Parma (Italy). Methodology: Pollen grains were sampled using a 7-day volumetric Hirst type spore trap. Chemvol high-volume cascade impactor equipped with stages PM>10µm, 10 µm>PM>2.5µm was used for detecting aeroallergens. In each stage polyurethane filters were use as an impacting substrate. Phl p 5 allergen was determined using an allergen specific ELISA. Antibodies for analysis were delivered by Allergopharma Joachim Ganzer KG, the industrial partner in this project. At each location both samplers were placed side-by-side. Results: Most of the allergen was collected in the PM>10µm fraction. Similar profiles between airborne pollen and the total allergenic load was observed during the pollen season. A good correlation was obtained between pollen count and allergen content of the air and a value of 2.5 pg/pollen grain of Poaceae was estimated. Discussion: This is the first year of this project. Nevertheless, results suggest that the allergenic load in outdoor air might be mainly due to pollen bursts. It supports the hypothesis that monitoring the allergens itself in ambient air might be an improvement in allergen exposure assessment. This work was supported in part by the European Agency for Health and Consumers EAHC, Luxembourg, under the grant agreement 2008110

Comparison between Airborne Pollen and Aeroallergen Quantification with the ChemVol Impact Sampler. Olive pollen vs Ole e 1

Comparison between Airborne Pollen and Aeroallergen Quantification with the ChemVol Impact Sampler. Olive pollen vs Ole e 1. Torres M.C.1, C. Antunes2, M.J. Velasco1, R. Ferro2, H. García-Mozo1, R. Ribeiro2, R.Brandao3, Galán, C1 and the HIALINE team4 1Department of Botany, Ecology and Plant Physiology, University of Córdoba 2Department of Chemistry, University of Évora, Portugal 3Department of Biology, University of Évora, Portugal 4J.T.M. Buters, Germany, M. Thibaudon, France, M. Smith, Great Britain, C. Galan, Spain, R. Brandao and C. Antunes, Portugal, G. Reese, Germany, R. Albertini, Italy, L. Grewling, Poland, A. Rantio-Lehtimäki, Finland, S. Jäger and U. Berger, Austria, I. Sauliene, Lithuania, L. Cecchi, Italy Nowadays, pollinosis is affecting a large percentage of population in the countries with a western life style. The existence of allergenic activity in the atmosphere is not only associated to pollen grains and fungal spores, but also to submicronic and paucimicronic biological particles. The origin of these allergens can be due to the rupture of pollen transported in the atmosphere or to the presence of allergens from other parts of the plant making amorphous material with an allergen load. Olive pollen is recognized as one of the main causes of allergic disease in the Mediterranean area. In this study we have tried to compare olive pollen count in the air and Ole e 1 as major allergen of this species, at two different localities in South of Europe: Evora (Portugal) and Córdoba (Spain). At each location both samplers were placed side-by-side. Pollen grains have been sampled using a volumetric Hirst type spore trap. Chemvol high-volume cascade impactor equipped with stages PM>10µm, 10 µm>PM>2.5µm were used for detecting aeroallergens. Ole e 1 major allergen was determined using allergen specific ELISA´s. Similar behaviour between pollen and the total allergenic load was observed during the pollen season. Nevertheless, at some occasions, during the previous and later period of the pollen season, airborne allergenic load was detected in South Spain, due to the contributions from other Oleaceae species. For this reason the use of these two different methodologies allow a better understanding of the allergenic load in the atmosphere. This work was supported in part by the European Agency for Health and Consumers EAHC, Luxembourg, under the grant agreement 20081107