Field-induced length changes in the spin-liquid candidate κ\kappa-(BEDT-TTF)2_2Cu2_2(CN)3_3

Measurements of the coefficient of thermal expansion on the spin-liquid candidate $\kappa$-(BEDT-TTF)$_2$Cu$_2$(CN)$_3$ have revealed distinct and strongly anisotropic lattice effects around 6 K - a possible spin-liquid instability. In order to study the effects of a magnetic field on the low-temperature spin-liquid state, dilatometric measurements have been conducted both as a function of temperature at \emph{B} = const. and as a function of field at \emph{T} = const. While the 6 K anomaly is found to be insensitive to magnetic fields \emph{B} $\leq$ 10 T, the maximum field applied, surprisingly strong \emph{B}-induced effects are observed for magnetic fields applied along the in-plane \emph{b}-axis. Above a threshold field of 0.5 T < \emph{B}$_c$ $\leq$ 1 T, a jump-like anomaly is observed in the \emph{b}-axis lattice parameter. This anomaly, which is located at 8.7 K at \emph{B} = 1 T, grows in size and shifts to lower temperatures with increasing the magnetic field. Although the anomaly bears resemblance to a first-order phase transition, the lack of hysteresis suggests otherwise.Comment: 3 pages, 3 figures, proceedings of ISCOM 2011, physica status solidi (c)(in press

Low-temperature lattice effects in the spin-liquid candidate κ\kappa-(BEDT-TTF)2_2Cu2_2(CN)3_3

The quasi-two-dimensional organic charge-transfer salt $\kappa$-(BEDT-TTF)$_2$Cu$_2$(CN)$_3$ is one of the prime candidates for a quantum spin-liquid due the strong spin frustration of its anisotropic triangular lattice in combination with its proximity to the Mott transition. Despite intensive investigations of the material's low-temperature properties, several important questions remain to be answered. Particularly puzzling are the 6\,K anomaly and the enigmatic effects observed in magnetic fields. Here we report on low-temperature measurements of lattice effects which were shown to be particularly strongly pronounced in this material (R. S. Manna \emph{et al.}, Phys. Rev. Lett. \textbf{104}, 016403 (2010)). A special focus of our study lies on sample-to-sample variations of these effects and their implications on the interpretation of experimental data. By investigating overall nine single crystals from two different batches, we can state that there are considerable differences in the size of the second-order phase transition anomaly around 6\,K, varying within a factor of 3. In addition, we find field-induced anomalies giving rise to pronounced features in the sample length for two out of these nine crystals for temperatures $T <$ 9 K. We tentatively assign the latter effects to $B$-induced magnetic clusters suspected to nucleate around crystal imperfections. These $B$-induced effects are absent for the crystals where the 6\,K anomaly is most strongly pronounced. The large lattice effects observed at 6\,K are consistent with proposed pairing instabilities of fermionic excitations breaking the lattice symmetry. The strong sample-to-sample variation in the size of the phase transition anomaly suggests that the conversion of the fermions to bosons at the instability is only partial and to some extent influenced by not yet identified sample-specific parameters

MUNDOS DA PRODUÇÃO DE ALIMENTO: A COMPETIÇÃO NO SISTEMA AGROALIMENTAR PELA LENTE DA ECONOMIA DAS CONVENÇÕES

A competição no sistema agroalimentar revela, atualmente, características semelhantes à de outros sistema produtivos, onde predominam os esforços para diferenciação na oferta de produtos. Atender às exigências da demanda tornou-se uma regra básica para a sobrevivência dos negócios, fazendo com que benefícios como praticidade, variedade, conveniência e qualidade ganhem crescente evidência. Contudo, ao contrário dos outros tipos de bens, qualidade nos alimentos é uma categoria analítica sujeita a distintas interpretações. Os problemas de contaminação e pobreza nutricional nos alimentos geram oportunidades para uma profunda reflexão sobre o sistema de oferta de alimentos e para as ações dos atores econômicos que procuram apresentar projetos de produtos cada vez mais diferenciados. Este trabalho apresenta uma leitura do panorama competitivo na oferta de alimento tendo como base o foco na qualidade. Por meio da Economia das Convenções analisa-se distintos mundos da produção de alimentos e como estes se organizam. A partir da contribuição de Michel Storper, procura-se demonstrar quais são os mundos da produção de alimentos.--------------------------------------------Competition on the agrofood has increasingly resembling that of others productive systems, where product diferentiation became a commom place. In order to survive businesses should satisfy demand requirements giving more attention to benefits like practicity, variety and convenience. Nevertheless, on the contrary of other kind of products quality in food is an analytical category subject to different interpretations. Food scares and poor nutritional levels are issues that raise opportunities for reflexion about food provision as well as for economic agents actions that search to provide projects of products increasingly differentiated. In this sense, this work present an interpretation of the food provision competitive landscape focusing on the prevailing quality claims. By applying conventions economy concepts worlds of food production are analysed and have its economical activities uncovered. From the contributions of Michael Storper the worlds of food production are demonstrated.Sistema Agroalimentar, estratégia, mundos da produção, agrofood system, strategy, worlds of production, Agribusiness,

Irrigação dos músculos papilares do ventrículo esquerdo do coração de caninos (Canis familiaris, L. 1758)

The irrigation of the papillary muscles, has incomplete information on the distribution of the arterial vessels. Objectifying to establish the origin of these arteries and their distribution in the left ventricle papillary muscles, we used 30 hearts of adult, male and female mongrel dogs. After the death, the heart was removed, washed and injected through the left coronary artery opening with an acetate solution of stained vinyl, neoprene latex 650 colored or 10% gelatin. The papillary muscles in all the applied techniques had been fixed with 10% formaldehyde solution. The dissection was carried out with the aid of a 40% sulfuric acid solution. For accomplishment of the radiography, we used mercury injection what assisted the assembly of the studied vascularization projects. Clearing technique of Spalteholz was applied for better visualization of the cardiac irrigation. We evidenced that the subauricular and subatrial papillary muscles are irrigated by the left coronary artery branches. The subauricular papillary muscle was blood-supplied by the interventricular paraconal and circumflex branches and the subatrial papillary muscle mainly by the circumflex branch. The sub-segments that supply the subauricular papillary muscle from the interventricular paraconal branch are the left collateral and ventricular branches and from the circumflex branch: left dorsal branches and intermedial (left ventricular marginal) and rarely from the left ventricular ridge (diaphragmatic branch). The subsegments of the circumflex branch that supply the subatrial papillary muscle are: intermedial (left ventricular marginal), from the left ventricular ridge (diaphragmatic branch), right dorsal branches and subsinuous interventricular branch. In some cases we observed the collateral branch and the proper interventricular paraconal branch reaching the portion of the vertex of the subatrial papillary muscle.A irrigação dos músculos papilares tem informações incompletas sobre a distribuição dos vasos arteriais. Objetivando estabelecer a origem destas artérias e sua distribuição nos músculos papilares do ventrículo esquerdo, utilizamos 30 corações de cães adultos, machos e fêmeas de raça não definida e de várias idades. Após o óbito, o coração foi removido, lavado em água corrente e em seguida injetado através do óstio da artéria coronária esquerda com uma solução de acetato de vinil corado, neoprene látex 650 corado ou gelatina a 10%. Os músculos papilares em todas as técnicas utilizadas foram fixados com solução de formol a 10%. A dissecação foi realizada de forma acelerada com o uso de solução de ácido sulfúrico a 40%. Para realização das radiografias utilizamos injeção de mercúrio o que auxiliou a montagem dos esquemas da vascularização estudada. Utilizamos a técnica de diafanização de Spalteholz para melhor visualizar a irrigação cardíaca. Evidenciamos que os músculos papilares subauricular e subatrial são irrigados pelos ramos da artéria coronária esquerda. O subauricular pelos ramos interventricular paraconal e circunflexo e o subatrial predominantemente pelo ramo circunflexo. Os subsegmentos que suprem o subauricular do ramo interventricular paraconal são os ramos: colateral e ventriculares à esquerda; e do ramo circunflexo são os ramos: dorsais à esquerda e intermédio (marginal ventricular esquerdo) e mais raramente o ramo da borda ventricular esquerda (ramo diafragmático). Os subsegmentos do ramo circunflexo que suprem o subatrial são os ramos: intermédio (marginal ventricular esquerdo), da borda ventricular esquerda (ramo diafragmático), ramos dorsais direito e ramo interventricular subsinuoso. Em alguns casos observamos o ramo colateral e o próprio ramo interventricular paraconal atingirem a porção do vértice do subatrial

A virtual environment system for spatial orientation research

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.Includes bibliographical references (leaves 74-75).by John de Souza.M.S

Archaeal abundance in post-mortem ruminal digesta may help predict methane emissions from beef cattle

The Rowett Institute of Nutrition and Health and SRUC are funded by the Rural and Environment Science and Analytical Services Division (RESAS) of the Scottish Government. The project was supported by DEFRA and DA funded Agricultural Greenhouse Gas Inventory Research Platform. Our thanks are due to the excellent support staff at the SRUC Beef Research Centre, Edinburgh, also to Graham Horgan of BioSS, Aberdeen, for conducting multivariate analysis.Peer reviewedPublisher PD

Rethinking clinical trials of transcranial direct current stimulation: Participant and assessor blinding is inadequate at intensities of 2mA

Copyright @ 2012 The Authors. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and 85 reproduction in any medium, provided the original author and source are credited. The article was made available through the Brunel University Open Access Publishing Fund.Background: Many double-blind clinical trials of transcranial direct current stimulation (tDCS) use stimulus intensities of 2 mA despite the fact that blinding has not been formally validated under these conditions. The aim of this study was to test the assumption that sham 2 mA tDCS achieves effective blinding. Methods: A randomised double blind crossover trial. 100 tDCS-naïve healthy volunteers were incorrectly advised that they there were taking part in a trial of tDCS on word memory. Participants attended for two separate sessions. In each session, they completed a word memory task, then received active or sham tDCS (order randomised) at 2 mA stimulation intensity for 20 minutes and then repeated the word memory task. They then judged whether they believed they had received active stimulation and rated their confidence in that judgement. The blinded assessor noted when red marks were observed at the electrode sites post-stimulation. Results: tDCS at 2 mA was not effectively blinded. That is, participants correctly judged the stimulation condition greater than would be expected to by chance at both the first session (kappa level of agreement (κ) 0.28, 95% confidence interval (CI) 0.09 to 0.47 p = 0.005) and the second session (κ = 0.77, 95%CI 0.64 to 0.90), p = <0.001) indicating inadequate participant blinding. Redness at the reference electrode site was noticeable following active stimulation more than sham stimulation (session one, κ = 0.512, 95%CI 0.363 to 0.66, p<0.001; session two, κ = 0.677, 95%CI 0.534 to 0.82) indicating inadequate assessor blinding. Conclusions: Our results suggest that blinding in studies using tDCS at intensities of 2 mA is inadequate. Positive results from such studies should be interpreted with caution.GLM is supported by the National Health & Medical Research Council of Australia ID 571090

Suscetibilidade de linhagens de Biomphalaria glabrata a cepas de Schistosoma mansoni

Com duas linhagens de Biomphalaria glabrata foi estudada a suscetibilidade de cinco cepas de Schistosoma mansoni resistentes e suscetíveis a esquistossomicidas. Três cepas do trematódeo oriundas de Porto Rico apresentaram desenvolvimento mais lento e menor índice de infecção em B. glabrata brasileira quando comparados com o comportamento de duas cepas de S. Mansoni provenientes do Brasil. Por outro lado, as cepas brasileiras do parasita desenvolve ram bem e infectaram mais de 90% dos exemplares de B. glabrata portorriquenhos. Entre os resultados, ressalta-se que cepas resistentes a esquistossomicidas poderão ser introduzidas por pacientes em diferentes áreas geográficas como Brasil e Porto Rico.Five strains of Schistosoma mansoni resistant and susceptible to schistosomicides were studied for infectivity of 2 strains of Biomphalaria glabrata one of Puerto Rican origin and the other of Brazilian origin. Puerto Rican strains of S. Mansoni developed more slowly and had a lower infectivity in Brazilian B. glabrata than did the Brazilian S. mansoni. However, Brazilian S. Mansoni developed as well in Puerto Rican snails as in Brazilian snails, indicating that drug resistant strains could easily be moved by travel of infected persons from one area to another