WorldWideScience

Sample records for merons

  1. Gauged merons

    Science.gov (United States)

    Samoilenka, A.; Shnir, Ya.

    2018-02-01

    We construct a new class of regular soliton solutions of the gauged planar Skyrme model on the target space S2 with fractional topological charges in the scalar sector. These field configurations represent Skyrmed vortices; they have finite energy and carry topologically quantized magnetic flux Φ =2 π n , where n is an integer. Using a special version of the product ansatz as a guide, we obtain by numerical relaxation various multimeron solutions and investigate the pattern of interaction between the fractionally charged solitons. We show that, unlike the vortices in the Abelian Higgs model, the gauged merons may combine short-range repulsion and long-range attraction. Considering the strong gauge coupling limit, we demonstrate that the topological quantization of the magnetic flux is determined by the Poincaré index of the planar components ϕ⊥=ϕ1+i ϕ2 of the Skyrme field.

  2. Gravitational catalysis of merons in Einstein-Yang-Mills theory

    Science.gov (United States)

    Canfora, Fabrizio; Oh, Seung Hun; Salgado-Rebolledo, Patricio

    2017-10-01

    We construct regular configurations of the Einstein-Yang-Mills theory in various dimensions. The gauge field is of meron-type: it is proportional to a pure gauge (with a suitable parameter λ determined by the field equations). The corresponding smooth gauge transformation cannot be deformed continuously to the identity. In the three-dimensional case we consider the inclusion of a Chern-Simons term into the analysis, allowing λ to be different from its usual value of 1 /2 . In four dimensions, the gravitating meron is a smooth Euclidean wormhole interpolating between different vacua of the theory. In five and higher dimensions smooth meron-like configurations can also be constructed by considering warped products of the three-sphere and lower-dimensional Einstein manifolds. In all cases merons (which on flat spaces would be singular) become regular due to the coupling with general relativity. This effect is named "gravitational catalysis of merons".

  3. Contribution of meron-like configurations to 't Hooft's disorder parameter

    International Nuclear Information System (INIS)

    Ragiadakos, C.; Viswanathan, K.S.; Simon Fraser Univ., Burnaby, British Columbia

    1980-01-01

    't Hooft's disorder parameter is written as a Euclidean functional integral over fields with singular boundary conditions. Meron-like configurations are constructed and their contributions to the disorder parameter is evaluated approximately. The calculated disorder parameter exhibits a confinement phase behaviour. (orig.)

  4. Real meromorphic differentials: a language for describing meron configurations in planar magnetic nanoelements

    Science.gov (United States)

    Bogatyrev, A. B.

    2017-10-01

    We use the language of real meromorphic differentials from the theory of Klein surfaces to describe the metastable states of multiply connected planar ferromagnetic nanoelements that minimize the exchange energy and have no side magnetic charges. These solutions still have sufficient internal degrees of freedom, which can be used as Ritz parameters to minimize other contributions to the total energy or as slow dynamical variables in the adiabatic approximation. The nontrivial topology of the magnet itself leads to several effects first described for the annulus and observed in the experiment. We explain the connection between the numbers of topological singularities of various types in the magnet and the constraints on the positions of these singularities following from the Abel theorem. Using multivalued Prym differentials leads to new meron configurations that were not considered in the classic work by Gross.

  5. Detection of volcanic activity at Mt. Etna using the experimental infrasound array at Meron, Israel

    Science.gov (United States)

    Applbaum, David; Price, Colin

    2015-04-01

    Volcanic activity has long been known as a natural producer of very low frequency acoustic waves, known as infrasound. Because of its proximity to both Europe and Tunisia, many observations of Mt. Etna have been made by various infrasound arrays, especially by IS48, the Tunisian infrasound array that is part of the International Monitoring System of the Comprehensive Nuclear Test Ban Treaty Organization. However, seasonal stratospheric wind changes cause infrasound to propagate well in the stratospheric waveguide either eastward or westward, in winter and summer respectively. For this reason, except in cases of wind reversal due to sudden stratospheric warming (SSW), all of the above observations were made in summer, from west of Mt. Etna. Upon studying the first four years of data from our experimental array in the north of Israel, we noticed that a great number of our winter-time detections come from a specific azimuth to the north west. Comparing these with the Reviewed Events Bulletin of CTBTO, we were able to indeed conclude that these detections likely come from Mt. Etna, over 2000 km away. Here we show some of these observations, the first extensive winter-time observations of Mt. Etna in infrasound

  6. Urinary sodium excretion and determinates among adults in Ethiopia

    African Journals Online (AJOL)

    Urinary sodium excretion and determinates among adults in Ethiopia: Findings from National STEPS survey. Feyissa Challa, Yewondwossen Tadesse, Kissi Mudie, Girum Taye, Terefe Gelibo, Alemayehu Bekele, Meron Sileshi, Tigist Getahun, Zeleke Geto, Abenezer Ayalkebet, Bikila Nagasa, Habtamu Teklie, Tefera ...

  7. The Quantum Hall Effect: Novel Excitations and Broken Symmetries

    OpenAIRE

    Girvin, Steven M.

    1999-01-01

    These pedagogical lecture notes present a general introduction to most aspects of the integer and fractional quantum Hall effects. This is followed by an extensive discussion of quantum Hall ferromagnetism, both for spins in single-layer systems and `pseudospins' in double-layer systems. The effective field theories describing various broken symmetry states and `skyrmion' and `meron' spin textures are derived and discussed in some detail. Pedagogical presentations on Berry phases and lowest L...

  8. Spontaneous nucleation and topological stabilization of skyrmions in magnetic nanodisks with the interfacial Dzyaloshinskii–Moriya interaction

    Energy Technology Data Exchange (ETDEWEB)

    Kolesnikov, A.G. [Laboratory of Thin Film Technologies, School of Natural Sciences, Far Eastern Federal University, Vladivostok 690950 (Russian Federation); Samardak, A.S., E-mail: samardak.as@dvfu.ru [Laboratory of Thin Film Technologies, School of Natural Sciences, Far Eastern Federal University, Vladivostok 690950 (Russian Federation); Stebliy, M.E.; Ognev, A.V.; Chebotkevich, L.A. [Laboratory of Thin Film Technologies, School of Natural Sciences, Far Eastern Federal University, Vladivostok 690950 (Russian Federation); Sadovnikov, A.V.; Nikitov, S.A. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation); Kotel' nikov Institute of Radioengineering and Electronics, Russian Academy of Sciences, Moscow 125009 (Russian Federation); Kim, Yong Jin; Cha, In Ho [Department of Materials Science and Engineering, Korea University, Seoul 02841 (Korea, Republic of); Kim, Young Keun, E-mail: ykim97@korea.ac.kr [Department of Materials Science and Engineering, Korea University, Seoul 02841 (Korea, Republic of)

    2017-05-01

    One of the major societal challenges is reducing the power consumption of information technology (IT) devices and numerous data centers. Distinct from the current approaches based on switching of magnetic single-domain nanostructures or on movement of domain walls under high currents, an original magnetic skyrmion technology offers ultra-low power, fast, high-density, and scalable spintronic devices, including non-volatile random access memory. Using data-driven micromagnetic simulations, we demonstrate the possibility of spontaneous nucleation and stabilization of different skyrmionic states, such as skyrmions, merons, and meron-like configurations, in heavy metal/ferromagnetic nanodisks with the interfacial Dzyaloshinskii–Moriya interaction (iDMI) as a result of quasi-static magnetization reversal only. Since iDMI is not easily modulated in real systems, we show that skyrmion stabilization is easily achievable by manipulating magnetic anisotropy, saturation magnetization, and the diameters of nanodisks. The state diagrams, presented in terms of the topological charge, allow to explicitly distinguish the intermediate states between skyrmions and merons and can be used for developing a skyrmionic medium, which has been recently proposed to be a building block for future spin-orbitronic devices.

  9. Nonlinear symmetry realizations and the generalized CP sup(n-1) model

    International Nuclear Information System (INIS)

    Santos, T.A.

    1982-01-01

    The genralized CP sup(n-1) model having U(p) as Gauge group in the two-dimension Euclidean space in the several existing formulations is presented. Such a model is described as a nonlinear symmetry realization which becames linear when restricted to a determined sub-groups treating therefore of fields which have values in the quocient space G/H. Classical instanton and meron solutions for this model are presented and the existence of a mechanism to generate a family of non auto-dual solutions with finite action, taking as starting point the instanton solutions, is demonstrated. (L.C.) [pt

  10. Orthodontic cements: immediate protection and fluoride release Cimentos ortodônticos: proteção imediata e liberação de flúor

    Directory of Open Access Journals (Sweden)

    Rogério Lacerda dos Santos

    2012-08-01

    Full Text Available OBJECTIVES: The objective of the authors was to evaluate fluoride release of 3 glass ionomer cements with immediate protection of fluoride varnish (Cavitine, SS White, divided into 3 groups: Group M (Meron, VOCO, Group V (Vidrion C, SS White and Group KC (Ketac-Cem, 3M ESPE. METHODS: Fluoride release was measured during 60 days by means of an ion-selective electrode connected to an ion analyzer. After 4 weeks, the test specimens were exposed to a solution of 0.221% sodium fluoride (1000 ppm of fluoride. RESULTS: Results showed that the cements reached a maximum peak of fluoride release in a period of 24 h. There was a statistically significant difference between the amount of fluoride released after the applications of fluoride among the groups from the 31st to 60th day (p> 0.05. CONCLUSION: The Vidrion C and Meron cements showed better performance to uptake and release fluoride when compared with Ketac-Cem cement.OBJETIVO: o objetivo desse estudo foi avaliar a liberação de flúor dos seguintes três cimentos de ionômero de vidro, com proteção imediata de verniz fluoretado (Cavitine, S. S. White: Meron / VOCO (Grupo M; Vidrion C / S. S. White (Grupo V; e Ketac Cem / 3M ESPE (Grupo KC. MÉTODOS: a liberação de flúor foi medida durante 60 dias, através de eletrodo íon seletivo conectado a um analisador de íons. Após quatro semanas, os corpos de prova foram expostos a uma solução de fluoreto de sódio a 0,221% (1.000ppm de flúor. RESULTADOS: os resultados evidenciaram que os cimentos atingiram o pico máximo de liberação de flúor com 24h após a presa inicial. Houve diferença estatisticamente significativa entre os grupos, quanto à quantidade de flúor liberado após as aplicações de flúor, do 31º ao 60° dia (p > 0,05. CONCLUSÃO: os cimentos Meron e Vidrion apresentaram maior capacidade de captação e liberação de flúor, em comparação ao cimento Ketac Cem.

  11. Conformally flat spaces and solutions to Yang-Mills equations

    International Nuclear Information System (INIS)

    Chaohao, G.

    1980-01-01

    Using the conformal invariance of Yang-Mills equations in four-dimensional manifolds, it is proved that in a simply connected space of negative constant curvature Yang-Mills equations admit solutions with any real number as their Pontryagin number. It is also shown that the space S 3 x S 1 which is the regular counterpart of the meron solution is one example of a class of solutions to Yang-Mills equations on compact manifolds that are neither self-dual nor anti-self-dual

  12. Genotoxicity and cytotoxicity induced by eluates from orthodontic glass ionomer cements in vitro

    Directory of Open Access Journals (Sweden)

    Fernanda Angelieri

    2018-01-01

    Full Text Available The aim of this study was to investigate genotoxicity and cytotoxicity of some orthodontic glass ionomer cements commercially available by means of the single cell gel (comet assay. For this purpose, five commercial orthodontic glass ionomer cements (Vidrion C®, Meron®, Optiband®, Multicure® and Ultra Band Lok® were tested in murine fibroblasts in vitro. For this purpose, eluates from each cement were prepared according manufactures instructions at 0, 2, 4, 8, 18, 32 and 64 days of immersion in artificial saliva at 37 °C. All orthodontic glass ionomer cements failed to induce cytotoxicity to murine fibroblasts for all periods evaluated in this study. However, Vidrion C® was able to induce genotoxicity after 64 days of exposure to eluates. Meron® also demonstrated genotoxicity as depicted by increasing DNA damage on 2nd day. Multicure® demonstrated genotoxicity on 32nd day and Ultra band Lok on 18th, 32nd days of exposure. Taken together, our results demonstrated that orthodontic cements derived from resin-modified glass ionomer composite (Multicure® and compomer (Ultra Band Lok® cause genetic damage in mammalian cells in vitro.

  13. The Wilson loop and some applications

    International Nuclear Information System (INIS)

    Bezerra, V.B.

    1983-04-01

    A simple relation between the classical Wilson loop and the angular deviation in the parallel displacement is found. An example of potentials which give field copies and which suplly the same classical Wilson loop for a particular trajectory is exhibited. The asymptotic behaviour of the Wilson loop for the BPST instanton and the meron, is discussed. By using the dimensional regularization technique to calculate the second order term of the quantum Wilson loop, the influence of geometrical factors for the residue in the pole due to contact points, cuspides and intersections, in function of the space-time ν, is investigated. Charge renormalization in Quantum electrodynamics is finally calculated by using the quantum Wilson loop. (L.C.) [pt

  14. The Wilson loop and some applications

    International Nuclear Information System (INIS)

    Bezerra, V.B.

    1983-01-01

    A simple relation between the classical Wilson loop and the angular deviation in the parallel shift is found. An example of potential which given field copies and which give the same classical Wilson loop for a given trajectory is exchibited. Afterwards, the asymptotic behaviour of the Wilson loop for the BPST instanton and meron is discussed. Using the dimensional regularization technique to calculate the second order term of Quantum Wilson loop, the influence of geometrical factors for the residue in the polo due to contact points, cusp and intersections, in function of the upsilon dimension of the space-time is investigated. Finally, the charge renormalization in Quantum Electrodynamics using Quantum Wilson loop is calculated. (L.C.) [pt

  15. Path-integral Monte Carlo method for the local Z2 Berry phase.

    Science.gov (United States)

    Motoyama, Yuichi; Todo, Synge

    2013-02-01

    We present a loop cluster algorithm Monte Carlo method for calculating the local Z(2) Berry phase of the quantum spin models. The Berry connection, which is given as the inner product of two ground states with different local twist angles, is expressed as a Monte Carlo average on the worldlines with fixed spin configurations at the imaginary-time boundaries. The "complex weight problem" caused by the local twist is solved by adopting the meron cluster algorithm. We present the results of simulation on the antiferromagnetic Heisenberg model on an out-of-phase bond-alternating ladder to demonstrate that our method successfully detects the change in the valence bond pattern at the quantum phase transition point. We also propose that the gauge-fixed local Berry connection can be an effective tool to estimate precisely the quantum critical point.

  16. Effect of thermocycling with or without 1 year of water storage on retentive strengths of luting cements for zirconia crowns.

    Science.gov (United States)

    Ehlers, Vicky; Kampf, Gabriel; Stender, Elmar; Willershausen, Brita; Ernst, Claus-Peter

    2015-06-01

    Bond stability between zirconia crowns and luting cement and between cement and dentin is a main concern; however, only limited evidence is available as to its longevity. The purpose of this in vitro study was to measure the retentive strengths of 7 self-adhesive cements (RelyX Unicem Aplicap, RelyX Unicem Clicker, RelyX Unicem 2 Automix, iCEM, Maxcem Elite, Bifix SE, SpeedCem), 2 adhesive cements with self-etch primers (Panavia 21, SEcure), 1 glass ionomer cement (Ketac Cem), 1 resin-modified glass ionomer cement (Meron Plus), and 1 zinc phosphate cement for luting zirconia crowns (LAVA) to extracted teeth after thermocycling with or without 1 year of water storage. Two-hundred-forty extracted human molars (2 treatments; n=10 per cement) were prepared in a standardized manner. All cements were used according to the manufacturers' recommendations. The intaglios of the crowns were treated with airborne-particle abrasion. After thermocycling (×5000, 5°C/55°C) with or without 1 year of water storage, the cemented ceramic crowns were removed by using a Zwick universal testing device. Statistical analyses were done with the Wilcoxon rank sum and the 2-independent-samples Kolmogorov-Smirnov test. Median retentive strengths [MPa] for specimens thermocycled only/thermocycled with 1 year of water storage were as follows: Panavia 21: 1.7/2.5, SEcure: 3.0/3.0, RelyX Unicem Aplicap: 3.1/3.4, RelyX Unicem Clicker: 4.1/4.2, RelyX Unicem 2 Automix: 3.8/3.1, iCEM: 2.3/2.7, Maxcem Elite: 3.0/3.2, Bifix SE: 1.7/1.7, SpeedCem: 1.3/1.6, Meron Plus: 3.1/2.7, Ketac Cem: 1.4/1.4, and zinc phosphate cement: 1.1/1.6. Statistically significant differences were found only among specimens thermocycled only or thermocycled with 1-year water storage (P<.001). Significant differences in retentive strengths were observed among cements after thermocycling only or thermocycling with 1 year of water storage, but not for the effect of the additional 1 year of water storage. Copyright © 2015

  17. Liberação de flúor de cimentos ortodônticos antes e após recarga com solução fluoretada = Fluoride release of orthodontic cements before and after recharge with fluoride solution

    Directory of Open Access Journals (Sweden)

    Santos, Rogério Lacerda dos

    2009-01-01

    Full Text Available Objetivo: O objetivo deste estudo foi comparar a liberação de flúor de cimentos de ionômero de vidro (CIV utilizados para cimentação ortodôntica, antes e após recarga de flúor. Metodologia: Foram avaliados três CIV: Meron (VOCO, Vidrion C (SS WHITE e Ketac-Cem (3M ESPE. A liberação de flúor foi medida através de eletrodo íon seletivo conectado a um analisador de íons após 1 h e 1, 3, 7, 14, 21 e 28 dias. Para avaliação da recarga de flúor e capacidade de retenção de flúor, os espécimes foram expostos a uma solução de fluoreto de sódio a 0,221 % (1000 ppm de flúor por 5 min nos dias 28, 30, 31 e 32 para medição após 24 h. Os dados foram analisados por ANOVA e teste de Kruskal-Wallis ao nível de significância de 0,05. Resultados: O padrão de liberação de flúor foi similar para os diferentes CIV avaliados, sendo que todos os materiais apresentaram uma maior liberação de flúor no primeiro dia e um decréscimo rápido até o sétimo dia. A exposição à solução fluoretada proporcionou maior liberação de flúor pelos materiais, mas sem atingir os mesmos níveis do primeiro dia. Conclusão: Os cimentos Meron e Vidrion C apresentaram maior liberação de flúor comparado ao cimento Ketac-Cem, tanto antes quanto após a recarga de flúor. O uso de solução com flúor permite elevar a quantidade de captação e liberação de flúor pelos CIVs

  18. Effect of a glaze/composite sealant on the 3-D surface roughness of esthetic restorative materials.

    Science.gov (United States)

    Perez, Cesar dos Reis; Hirata, Raphael Júnior; da Silva, Antonio Henrique Monteiro da Fonseca Thomé; Sampaio, Eduardo Martins; de Miranda, Mauro Sayão

    2009-01-01

    The main goal of the current study was to evaluate the surface roughness of tooth-colored restorative materials after different finishing/polishing protocols, including a liquid polisher (BisCover, BISCO, Schaumburg, IL, USA). The restorative materials tested included two nanofilled resin composites (Filtek Supreme, 3M Dental Products, St Paul, MN, USA and Grandio, Voco, Cuxhaven, Germany), one resin-modified glass ionomer cement (Vitremer, 3M Dental Products) and one conventional glass ionomer cement (Meron Molar ART, Voco). The finishing/polishing methods were divided into five groups: G1 (compression with Mylar matrix), G2 (finishing with diamond burs), G3 (Sof-Lex, 3M Dental Products), G4 (BisCover, BISCO, after diamond burs) and G5 (BisCover after Sof-Lex). Five cylindrical specimens of each material were prepared for each group according to the manufacturer's instructions. The finishing/polishing methods were performed by a single operator in one direction to avoid variations at low speed (15,000 RPM). The surface roughness was evaluated using a 3-D scanning instrument with two parameters considered (Ra and Rz). The data was analyzed using one-way ANOVA followed by a multiple comparison Tukey's test. The results showed that BisCover (BISCO) was capable of reducing surface roughness and provided polished surfaces for all materials, enhancing smoothness over already polished surfaces (Sof-Lex, 3M Dental Products) and achieving polishing after finishing with diamond burs.

  19. Role of spin diffusion in current-induced domain wall motion for disordered ferromagnets

    KAUST Repository

    Akosa, Collins Ashu

    2015-03-12

    Current-induced spin transfer torque and magnetization dynamics in the presence of spin diffusion in disordered magnetic textures is studied theoretically. We demonstrate using tight-binding calculations that weak, spin-conserving impurity scattering dramatically enhances the nonadiabaticity. To further explore this mechanism, a phenomenological drift-diffusion model for incoherent spin transport is investigated. We show that incoherent spin diffusion indeed produces an additional spatially dependent torque of the form ∼∇2[m×(u⋅∇)m]+ξ∇2[(u⋅∇)m], where m is the local magnetization direction, u is the direction of injected current, and ξ is a parameter characterizing the spin dynamics (precession, dephasing, and spin-flip). This torque, which scales as the inverse square of the domain wall width, only weakly enhances the longitudinal velocity of a transverse domain wall but significantly enhances the transverse velocity of vortex walls. The spatial-dependent spin transfer torque uncovered in this study is expected to have significant impact on the current-driven motion of abrupt two-dimensional textures such as vortices, skyrmions, and merons.

  20. Topological defect formation in rotating binary dipolar Bose–Einstein condensate

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiao-Fei, E-mail: xfzhang@ntsc.ac.cn [Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi’an 710600 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Department of Engineering Science, University of Electro-Communications, Tokyo 182-8585 (Japan); Han, Wei [Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi’an 710600 (China); Jiang, Hai-Feng [Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi’an 710600 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Liu, Wu-Ming [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Saito, Hiroki [Department of Engineering Science, University of Electro-Communications, Tokyo 182-8585 (Japan); Zhang, Shou-Gang [Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi’an 710600 (China); University of Chinese Academy of Sciences, Beijing 100049 (China)

    2016-12-15

    We investigate the topological defects and spin structures of a rotating binary Bose–Einstein condensate, which consists of both dipolar and scalar bosonic atoms confined in spin-dependent optical lattices, for an arbitrary orientation of the dipoles with respect to their plane of motion. Our results show that the tunable dipolar interaction, especially the orientation of the dipoles, can be used to control the direction of stripe phase and its related half-vortex sheets. In addition, it can also be used to obtain a regular arrangement of various topological spin textures, such as meron, circular and cross disgyration spin structures. We point out that such topological defects and regular arrangement of spin structures arise primarily from the long-range and anisotropic nature of dipolar interaction and its competition with the spin-dependent optical lattices and rotation. - Highlights: • Effects of both strength and orientation of the dipoles are discussed. • Various topological defects can be formed in different parameter regions. • Present one possible way to obtain regular arrangements of spin textures.

  1. Minimalism in architecture: Materials as an instrument of perception

    Directory of Open Access Journals (Sweden)

    Vasilski Dragana

    2013-01-01

    Full Text Available Materials, as an instrument for author's report of his ideas and puts them into the space and time, is a recurring theme of architecture, from the time of Vitruvius triad (firmitas. In minimalism, materials shape space and express its essence, which is the irreducible minimum. The approach in this paper is methodologically defined by architecture domain that is art within it, therefore what the visual means are materials, with the aspiration to discover meaning in what we see. The principles of visual perception are primarily active in the field of law perceptions reached by the psychology of perception, specifically the theory called Gestalt. As the material contained in the tangible components, and sentient, such a relationship is required for duality of materialization, which is achieved by the use of their material expression of immateriality. This expression gives the truth of immateriality (natural materials, tactile value (structure and texture and the 'movement' of the material (the ability to transform. Author's access to the material as an instrument of expression immaterial, provided the concept of minimalist architecture at a higher artistic level (Peter Cumtor and causing severe emotional reaction when meeting also created architectural works (Tadao Ando. Transformations of materials are achieved through the exploration of new treatments and techniques (Kengo Kuma, and the development of technology to unimaginable limits changes the way of understanding reality (Herzog & de Meron. Researching of materials, in the way of its application, can be achieved understanding of minimalism in the architecture as an idea.

  2. Assessment of the mechanical properties of glass ionomer cements for orthodontic cementation

    Directory of Open Access Journals (Sweden)

    Marcel M. Farret

    2012-12-01

    Full Text Available OBJECTIVE: To evaluate the mechanical properties of three glass ionomers cements (GICs used for band cementation in Orthodontics. METHODS: Two conventional glass ionomers (Ketac Cem Easy mix/3M-ESPE and Meron/Voco and one resin modified glass ionomer (Multi-cure Glass ionomer/3M-Unitek were selected. For the compressive strength and diametral tensile strength tests, 12 specimens were made of each material. For the microhardness test 15 specimens were made of each material and for the shear bond strength tests 45 bovine permanent incisors were used mounted in a self-cure acrylic resin. Then, band segments with a welded bracket were cemented on the buccal surface of the crowns. For the mechanical tests of compressive and diametral tensile strength and shear bond strength a universal testing machine was used with a crosshead speed of 1,0 mm/min and for the Vickers microhardness analysis tests a Microdurometer was used with 200 g of load during 15 seconds. The results were submitted to statistical analysis through ANOVA complemented by Tukey's test at a significance level of 5%. RESULTS: The results shown that the Multi-Cure Glass Ionomer presented higher diametral tensile strength (p OBJETIVO: avaliar as propriedades mecânicas de três cimentos de ionômero de vidro (CIVs utilizados para cimentação de anéis ortodônticos. MÉTODOS: foram utilizados dois CIVs convencionais (Ketac Cem Easy mix/3M-ESPE e Meron/Voco e um CIV modificado por resina (Multi-Cure Glass ionomer/3M-Unitek. Para os testes de resistência à compressão e tração diametral, foram confeccionados 12 corpos de prova de cada material. Para os testes de microdureza, foram confeccionados 15 corpos de prova de cada material; para os testes de resistência de união ao cisalhamento, foram utilizados 45 dentes bovinos incluídos em resina acrílica, sobre os quais foi cimentada uma lâmina de anel ortodôntico com braquete soldado a ela para a realização dos ensaios. Para os

  3. The influence of long term water immersion on shear bond strength of amalgam repaired by resin composite and mediated by adhesives or resin modified glass ionomers.

    Science.gov (United States)

    Pilo, R; Nissan, J; Shafir, H; Shapira, G; Alter, E; Brosh, T

    2012-07-01

    To assess the shear bond strength between amalgam and resin composite mediated by either multipurpose adhesive systems or RMGI when subjected to long term immersion in saline. Part I: Cylindrical specimens (6 mm × 6 mm) composed of equal parts of sandblasted set amalgam (Oralloy) and composite (Z-100), with a thin layer of either Scotchbond Multipurpose, All Bond 2, Amalgam Bond Plus, High Q Bond Plus or Vitrebond in between were fabricated (n = 100 × 5). Each group was divided into 3 subgroups, immersed in saline at 37 °C for either 48 h, 3 or 6 months, followed by thermocycling (5000; 5/55 °C) and shear bond strength testing (SBS). Part II: Identical specimens were fabricated with intermediary of either Ketac Cem, Fuji Lining LC, Rely X Luting, Fuji Plus or Meron Plus (n = 100 × 5). Immersion periods, followed by thermocycling and SBS testing as in Part I. Two representative specimens from each subgroup were sectioned and inspected under SEM. The two classes of intermediary agents yielded SBS which differed mainly in the 6 months incubation period. While multipurpose adhesives provided SBS values of ~9-10 MPa RMGI provided higher SBS of ~16 MPa. All Bond 2 and Amalgam Bond Plus exhibited deterioration of SBS during the 6 month period as well as Rely X Luting. Gap sizes between 0.5 and 3 μm exist between all intermediaries and the amalgam; on the other hand all intermediaries exhibit gap-free interfaces between the adhesives/RMGI and the composite. Vitrebond in particular and RMGIs in general can serve as an excellent coupler of resin composite to amalgam, providing a durable bond. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Continuous Advances in QCD 2000 - Proceedings of the Fourth Workshop

    Science.gov (United States)

    Voloshin, M. B.

    The Table of Contents for the full book PDF is as follows: * 1. Dynamics in Supersymmetric Non-Abelian Gauge Theories * Microscopic Pictures of Dynamical Symmetry Breaking in Supersymmetric SU(NC), USP(2NC) and SO(Nc) Theories * Renormalization Group Flow in AdS/CFT and the Choice of Vacuum * Gauge Field Theory Beta-Functions, Holographic RG Flow and Wilson Loops * Wilson Loops in N=4 SYM Theory * The Effective Superpotential and BPS Domain Walls in 𝒩 = 1 SYM (on R3 × S1) * Evidence for Zerobranes in (SUSY) Gluodynamics * 2. General Aspects of Perturbative and Nonperturbative QCD * Overlapping Instantons * Dirac Spectrum in Adjoint QCD * Magnetic ZN Symmetry and the Deconfining Phase Transition * Can Merons Describe Confinement? * String Representation of Gauge Theories * Center Vortex Model for the Infrared Sector of Yang-Mills Theory * Nonperturbative Calculation of Scattering Amplitudes * (Field) Symmetrization Selection Rules * 3. Properties of Hadrons and Hadronic Processes * Integrability of Twist-Three Evolution Equations in QCD * Off-Forward Parton Distributions and Impact Parameter Dependent Parton Structure * QCD Structure Functions at Small x * Flow Equations in the Light-Front QCD * Calculations of EDMs of Hadrons via QCD Sum Rules * Primordial Galactic Magnetic Fields from the QCD Phase Transition * 4. Heavy Quark Physics * Conceptual Aspects of QCD Factorization in Hadronic B Decays * Applications of QCD Factorization in Hadronic B Decays * QCD Corrections to Lifetime Differences of Bs-Mesons * Width Difference in the D0-D¯0 System * QCD Sum Rules for Heavy Flavors * Pattern of Lifetimes of Beauty Hadrons and Quark-Hadron Duality in Heavy Quark Expansion * pNRQCD: Concepts and Applications * List of Participants

  5. Quark confinement: Dual superconductor picture based on a non-Abelian Stokes theorem and reformulations of Yang-Mills theory

    Science.gov (United States)

    Kondo, Kei-Ichi; Kato, Seikou; Shibata, Akihiro; Shinohara, Toru

    2015-05-01

    The purpose of this paper is to review the recent progress in understanding quark confinement. The emphasis of this review is placed on how to obtain a manifestly gauge-independent picture for quark confinement supporting the dual superconductivity in the Yang-Mills theory, which should be compared with the Abelian projection proposed by 't Hooft. The basic tools are novel reformulations of the Yang-Mills theory based on change of variables extending the decomposition of the SU(N) Yang-Mills field due to Cho, Duan-Ge and Faddeev-Niemi, together with the combined use of extended versions of the Diakonov-Petrov version of the non-Abelian Stokes theorem for the SU(N) Wilson loop operator. Moreover, we give the lattice gauge theoretical versions of the reformulation of the Yang-Mills theory which enables us to perform the numerical simulations on the lattice. In fact, we present some numerical evidences for supporting the dual superconductivity for quark confinement. The numerical simulations include the derivation of the linear potential for static interquark potential, i.e., non-vanishing string tension, in which the "Abelian" dominance and magnetic monopole dominance are established, confirmation of the dual Meissner effect by measuring the chromoelectric flux tube between quark-antiquark pair, the induced magnetic-monopole current, and the type of dual superconductivity, etc. In addition, we give a direct connection between the topological configuration of the Yang-Mills field such as instantons/merons and the magnetic monopole. We show especially that magnetic monopoles in the Yang-Mills theory can be constructed in a manifestly gauge-invariant way starting from the gauge-invariant Wilson loop operator and thereby the contribution from the magnetic monopoles can be extracted from the Wilson loop in a gauge-invariant way through the non-Abelian Stokes theorem for the Wilson loop operator, which is a prerequisite for exhibiting magnetic monopole dominance for quark