Magnetic Vortices in High Temperature Superconductors

It is suggested that modes, observed in recent neutron scattering experiments by Lake {\it et al.}, on La$_{2-x}$Sr$_x$CuO$_4$ in strong magnetic fields ($\approx$ 7 T), are due to the existence of antiferromagnetic moments associated with the cores of vortices generated by the field. These moments form one-dimensional chains along the $c$-axis (the vortex axis), which at finite temperatures are disordered. At temperatures higher than 10 K the correlation length gets shorter than the lattice parameter, resulting in no scattering from coherent spin-waves above that temperature. The bandwidth of the spin-waves is estimated to be $\approx$ 4 meV in accordance with the observations.Comment: 3 pages, 1 figur

Spin dynamics in the stripe phase of the cuprates

Within a model that supports stripe spin and charge order coexisting with a d$_{x^2-y^2}$-wave superconducting phase, we study the self-consistently obtained electronic structure and the associated transverse dynamical spin susceptibility. In the coexisting phase of superconducting and static stripe order, the resulting particle-hole continuum can strongly damp parts of the low-energy spin wave branches. This provides insight into recent inelastic neutron scattering data revealing the dispersion of the low-energy collective magnetic modes of lanthanum based cuprate superconductors.Comment: 4 pages, 3 figure

Thermoelectric Driven Ring Currents in Single Molecules and Graphene Nanoribbons

In a Seebeck coefficient measurement with vanishing transport current, it is usually assumed that local currents cancel as well. Here we present the existence of local electric currents in single molecule junctions under such experimental conditions. In contrast to ring currents induced by a magnetic field, the thermoelectric driven ring currents can show up in a variety of different patterns depending on how the molecule is connected to the leads. We derive an analytic expression to calculate local currents in tight binding models and use it to qualitatively predict the current patterns and to show that, in alternant molecules, thermoelectric driven ring currents are odd as a function of a gate voltage. Finally, we show that local currents exist in gated graphene nanoribbons as well

Magnetic Vortices In High Temperature Superconductors

Consiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7 Rome / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Der Einfluss von Glykol-Wasser-Gemischen auf die Messrichtigkeit von Rechenwerken bei Waermezaehlern fuer thermische Solaranlagen

In order to measure the energy supplied by a solar thermal plant it is necessary to have a heat counter that is suitable for use with the glycol-water mixtures commonly used as thermal carriers in the collector circuit of solar plants. Funded by the Bundesstiftung Umwelt (Federal Foundation for the Environment) and the heat counter industry this project was dedicated to determining the measuring accuracy of throughflow sensors in heat counters operating in an industrially produced glycol-water mixture that is widely used in solar plants, consisting of 50% vol. TYFOCOR L (96% vol. propylene glycol, 4% vol. additives) and 50% vol. water. The only type found suitable for use in solar plants was the impeller counter. In this follow-up study 8 arithmetic units that are widely used in heat counters were examined for their suitability for use in solar thermal plants.Zur Bestimmung der mit einer thermischen Solaranlage gewonnenen Energie werden Waermezaehler benoetigt, die fuer die in den Kollektorkreislaeufen von Solaranlagen ueblicherweise verwendeten Glykol-Wasser-Gemischen als Waermetraeger geeignet sind. In einem von der Deutschen Bundesstiftung Umwelt und von der Waermezaehlerindustrie unterstuetzten Vorhaben, wurde unter Verwendung eines industriell hergestellten und in solaren Anlagen weitverbreiteten Glykol-Wasser-Gemisches, bestehend aus 50 Vol.-% TYFOCOR L (96 Vol.-% Propylenglykol, 4 Vol.-% Additive) und 50 Vol.-% Wasser, die Messrichtigkeit von in Waermezaehlen verwendeten Durchflusssensortypen untersucht. Es erwiesen sich nur die Fluegelradzaehler fuer den Einsatz in Solaranlagen geeignet. In diesem weiterfuehrenden Bericht wurden acht haeufig verwendete Rechenwerke fuer Waermezaehler einer Untersuchung auf ihre Eignung in thermischen Solaranlagen unterzogen. (orig.)SIGLEAvailable from TIB Hannover: RR 9173(24) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Forma??o e desempenho do visitador na pr?tica socioeducativa do Programa Primeira Inf?ncia Melhor

Made available in DSpace on 2015-04-14T14:23:10Z (GMT). No. of bitstreams: 1 430431.pdf: 1364439 bytes, checksum: 66142dc00c9d3a9fbb8e87d9ba84556f (MD5) Previous issue date: 2011-01-14Este estudo teve como objetivo investigar as necessidades de forma??o inicial e continuada do Visitador no Programa Primeira Inf?ncia Melhor, considerando seu desempenho na orienta??o das fam?lias atendidas. Para o levantamento dos dados, foi utilizado um question?rio com perguntas fechadas tipo Lickert-5 acrescido, ao final, de duas quest?es abertas - caracterizando uma pesquisa de natureza aplicada, atrav?s do m?todo quantitativo. Participaram da amostra 121 Visitadores de 17 Munic?pios que desenvolvem o Programa no Estado. Buscou-se com este estudo analisar a interpreta??o dos Visitadores com rela??o as suas viv?ncias profissionais e o seu entendimento quanto ao papel que assumem no trabalho junto ?s fam?lias, para enfim, refletir sobre as necessidades de forma??o evidenciadas no instrumento de pesquisa. A an?lise revelou que os Visitadores possuem um bom entendimento de seu papel na estrutura do Programa e do objetivo pretendido pelo PIM, por?m apontou algumas inadequa??es importantes no modo como desenvolvem seu trabalho junto ?s fam?lias, indicando a necessidade de articular ? capacita??o o exerc?cio de acompanhar o trabalho dos Visitadores na pr?tica, a fim de garantir n?o s? a supervis?o de seu desempenho, como tamb?m a elabora??o de um diagn?stico que fundamente os planos de capacita??o uma pr?tica ainda pouco disseminada no cotidiano das equipes municipais. Tamb?m revelou a habilidade dos respondentes em elaborar uma percep??o bastante coerente sobre os aspectos de sua forma??o e sobre as estrat?gias necess?rias para qualific?-la, sugerindo que os momentos de escuta do Visitador s?o um princ?pio b?sico para a qualifica??o dos trabalhos