Phase coherence in the inelastic cotunneling regime

Two quantum dots with tunable mutual tunnel coupling have been embedded in a two-terminal Aharonov-Bohm geometry. Aharonov-Bohm oscillations are investigated in the cotunneling regime. Visibilities of more than 0.8 are measured indicating that phase-coherent processes are involved in the elastic and inelastic cotunneling. An oscillation-phase change of pi is detected as a function of bias voltage at the inelastic cotunneling onset.Comment: 4 pages, 4 figure

Coherent probing of excited quantum dot states in an interferometer

Measurements of elastic and inelastic cotunneling currents are presented on a two-terminal Aharonov--Bohm interferometer with a Coulomb blockaded quantum dot embedded in each arm. Coherent current contributions, even in magnetic field, are found in the nonlinear regime of inelastic cotunneling at finite bias voltage. The phase of the Aharonov--Bohm oscillations in the current exhibits phase jumps of $\pi$ at the onsets of inelastic processes. We suggest that additional coherent elastic processes occur via the excited state. Our measurement technique allows the detection of such processes on a background of other inelastic current contributions and contains information about the excited state occupation probability and the inelastic relaxation rates

Plaquette bond order wave in the quarter-filled extended Hubbard model on the checkerboard lattice

An extended Hubbard model (including nearest-neighbor repulsion and antiferromagnetic spin exchange) is investigated on the frustrated checkerboard lattice, a two-dimensional analog of the pyrochlore lattice. Combining Gutzwiller renormalized mean-field (MF) calculations, exact diagonalization (ED) techniques, and a weak-coupling renormalization group (RG) analysis we provide strong evidence for a crystalline valence bond plaquette phase at quarter-filling. The ground state is twofold degenerate and breaks translation symmetry. The bond energies show a staggering while the charge distribution remains uniform.Comment: 8 pages, 6 figures, published versio

Reparação de perfurações experimentais (trepanações) seladas com diferentes materiais obturadores de canais radiculares

Orientador: Luiz ValdrighiDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: o presente trabalho se propôs a realizar, em dentes de cães, a análise histopatológica da reação dos tecidos periodontais de suporte, diante da realização de perfurações experimentais (trepanações), seladas com diferentes materiais. F oram utilizados os segundos, terceiros e quartos pré-molares inferiores de cães adultos jovens, num total de 48 dentes. As perfurações experimentais foram realizadas nas raizes. mesiais dos dentes e seladas com 3 materiais, divididos em 4 grupos: Grupo I - Endomethasone; Grupo 11 - Sealapex; Grupo li - Hidroxiapatita e Endomethasone; Grupo IV - Hidroxiapatita e Sealapex . As observações foram efetuadas nos tempos experimentais de 14 e 90 dias. Os resultados mostraram que, no periodo experimental de 14 dias, o quadro histopatológico era caracterizado por sinais de destruição do ligamento periodontal, pelo processo inflamatório predominantemente constituído de infiltrado inflamatório de grau médio, sem diferenças apreciáveis entre os grupos estudados. No período experimental de 90 dias, o quadro histopatológico predominante era de inflamação muito discreta ou ausente, com sinais de reparação, à exceção do grupo IV que, nesse período, apresentou uma persistência de inflamação crônica ao redor do material extruído no ligamento periodontal. Aos 90 dias, os melhores resultados foram alcançados nos grupos I e lI, nos quais não foi utilizada a hidroxiapatita como anteparo do material selador. Palavras-chave canal radicular - tratamento; cão como animal de laboratório; dentes - histopatologiaAbstract: The purpose of this study was to evaluate, in dog teeth, the periodontal support tissues reaction to lateral root perforations, sealed with different materials. Second, third and fourth mandibular premolars of adult-young dogs have been used in a total of 48 teeth. The experimental perforations were created in mesial roots of the teeth and sealed with three materials, shared in four diferent groups: Group I - perforations ~ealed with Endomethasone; Group 11 - perforations sealed with Sealapex; Group 111 - perforations sealed with Endomethasone, after the placement of an internal matrix of hydroxylapatite; Group IV - perforations sealed with Sealapex, after the placement of an internal matrix of hydroxylapatite; The animal were sacrified at the intervals of 14 and 90 days after the experimento The results have shown that in the period of 14 days, the histopathological board was characterized by the destruction signs of the periodontal ligament through an inflammatory process mostly constitued of a medium degree of cell infiltrate without differences among the groups. At 90 days the predominating board was a mild or even an absent inflammation with signs of reparation, less group IV which has shown a chronical inflammation around the material extruded into the periodontal ligament. The best results were reached in groups I and 11, at 90 days, in which hydroxylapatite was not used as a internal matrix. Key-words . Root canal therapy~ dog as laboratory animals~ teeth histopathologyMestradoEndodontiaMestre em Clínica Odontológic

Reparo de perfurações na furca de dentes de cães, seladas com endomethasone com e sem barreiras de hidroxido e sulfato de calcio

Orientador: Luiz ValdrighiTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: A reparação de perfurações radiculares na região de furca de dentes, seladas imediatamente foi avaliada clínica, histológica e radiograficamente. Vinte e quatro dentes pré-molares inferiores, de cães adultos jovens, receberam perfurações experimentais na região de furca. Os materiais utilizados para a pesquisa foram: o Endomethasone, o cimento de hidróxido de cálcio e o sulfato de cálcio. O Endomethasone foi o material utilizado para o preenchimento do trajeto das perfurações, enquanto o cimento de hidróxido de cálcio e o sulfato de cálcio foram utilizados como anteparo, ou barreira para melhorar as condições de condensar o Endomethasone. Os dentes foram selados com resina composta fotopolimerizável precedida de condicionamento ácido e aplicação de adesivo dentinário. Após períodos experimentais, de 14 e 90 dias, os animais foram sacrificados e as estruturas anatomicas foram processadas para a análise histológica no microscópio óptico. A avaliação clínica mostrou que não houve envolvimento periodontal dos dentes analisados. Radiograftcamente, após 90 dias, não foram observadas perdas ósseas significativas. As avaliações histopatológicas mostraram que a colocação de uma barreira melhora as condições de condensação do material selador e tende a evitar sua extrusão e que não houve, em nenhum dos casos analisados, a completa reparação das perfurações com material calcificadoAbstract: The purpose of the present study was to evaluate the histological and radiological response to two. materials used as a matrix under a zinc oxide-eugenol cement used as a sealant in the repair of furcation perforations in experimental animals. After anesthesia, rootcanal treatment of canaIs with zinc oxide-eugenol cement, furcal perforations were made in 24 lower premolar (p3 and P4) teeth of mongrel dogs, with L.N. burs. The perforated teeth were random1y divided into 3 groups of 8 teeth: Group I - perforations sealed with Endomethasone; Group II - perforations sealed with Endomethasone after the placement of an internal matrix of calcium hydroxide; Group m - perforations sealed with Endomethasone after the placement of an internal matrix of calcium sulfate. Pulp chamber of all teeth were filled with composite resin after acid etching and application of dentinal adhesive. Animals were sacrificed after 14 and 90 days. The teeth and surrounding structures were processed for light microscopy. The conclusion of this study is that a placement of a barrier at the pulp chamber aspect of a furcation perforation did not result in superior healing, compared with the use of zinc oxide-eugenol cement alone and complete healing of furcation perforations with hard tissue was not observed.DoutoradoEndodontiaDoutor em Clínica Odontológic

Wildlife and humans in outdoor recreational areas near cities

<p>In Naherholungsräumen von Städten herrscht reger Betrieb: am Tag, aber auch in Randzeiten und teils gar in der Nacht. Wildtiere und deren Lebensräume geraten dadurch unter Druck. In stark frequentierten Gebieten sind Rehe weniger aktiv und für viele Wildtierarten ist der Lebensraum reduziert. Wildruhezonen, eine eingeschränkte Er- schliessung und die Lenkung der Besuchenden verbessern die Lebensbedingungen der Wildtiere.</p> <p> </p