Histological analyses of thermal effect caused by 1.2 W diode laser irradiation at rat periodontal pockets

The aim of this in vivo study was to evaluate the thermal effects caused by 810 nm 1.2 W diode laser irradiation of periodontal tissues. Despite all data available concerning the laser application for periodontal treatment, one of the most relevant challenges is to prevent the harmful tissue heating induced by different clinical protocols. Periodontal pockets were induced at molars in 96 rats. Several irradiation powers under CW mode were investigated: 0, 400, 600, 800, 1000, 1200 mW. The pockets were irradiated using a 300 A mu m frontal illumination fiber. The animals were killed at 4 or 10 days after irradiation. The mandible was surgically removed and histologically processed. The histological sections stained with H/E demonstrated that irradiation parameters up to 1000 mW were thermally safe for the periodontal tissues. The sections stained with Brown & Brenn technique evidenced bacteria in the periodontal tissues. Consequently, the diode laser irradiation as a unique treatment was not capable to eliminate bacteria of the biofilm present in the pockets. According to the methodology used here, it was concluded that the thermal variation promoted by a diode laser can cause damage to periodontal tissues depending on the energy density used. The 1.2 W diode laser irradiation itself does not control the bacteria present in the biofilm of the periodontal pockets without mechanical action. The knowledge of proper high intensity laser parameters and methods of irradiation for periodontal protocols may prevent any undesirable thermal damage to the tissues.

Femtosecond laser ablation on dental hard tissues-Analysis of ablated profile near an interface using local effective intensity

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Surface roughness of enamel and four resin composites

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Cooper pair dispersion relation for weak to strong coupling

Cooper pairing in two dimensions is analyzed with a set of renormalized equations to determine its binding energy for any fermion number density and all coupling assuming a,generic pairwise residual interfermion interaction. Also considered are Cooper pairs (CP's) with nonzero center-of-mass momentum (CMM) and their binding energy is expanded analytically in powers of the CMM up to quadratic terms. A Fermi-sea-dependent linear term in the CMM dominates the pair excitation energy in weak coupling (also called the BCS regime) while the more familiar quadratic term prevails in strong coupling (the Bose regime). The crossover, though strictly unrelated to BCS theory per se, is studied numerically as it is expected to play a central role in a model of superconductivity as a Bose-Einstein condensation of CPs where the transition temperature vanishes for all dimensionality d less than or equal to 2 for quadratic dispersion, but is nonzero for all d greater than or equal to 1 for linear dispersion.

Consistent modified gravity: dark energy, acceleration and the absence of cosmic doomsday

We discuss modified gravity which includes negative and positive powers of curvature and provides gravitational dark energy. It is shown that in GR plus a term containing a negative power of curvature, cosmic speed-up may be achieved while the effective phantom phase (with w less than -1) follows when such a term contains a fractional positive power of curvature. Minimal coupling with matter makes the situation more interesting: even 1/R theory coupled with the usual ideal fluid may describe the (effective phantom) dark energy. The account of the R(2) term (consistent modified gravity) may help to escape cosmic doomsday.

Semiclassical approach to the decay of protons in circular motion under the influence of gravitational fields

We investigate the possible decay of protons in geodesic circular motion around neutral compact objects. Weak and strong decay rates and the associated emitted powers are calculated using a semiclassical approach. Our results are discussed with respect to distinct ones in the literature, which consider the decay of accelerated protons in electromagnetic fields. A number of consistency checks are presented along the paper.

Remarks on Parametric Surface Waves in a Nonlinear and Non-Ideally Excited Tank

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Efeitos da radiação laser de dióxido de carbono em tecido ósseo: estudo macroscópico em ratos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A industrialização das editoras e dos livros didáticos nos Estados Unidos (do século XIX ao começo do século XX)

Cet article examine la création de l'industrie du livre didactique aux États-Unis à partir des années 30 du XIXe siècle. Dès les années 20 de ce siècle, des maisons d'éditions sises dans les villes de New York et Boston étaient déjà capables de publier différents types de livres didactiques et de petits livres pour enfants et de les vendre aux quatre coins du pays, où elles avaient détaché des fonctionnaires pour ce faire. À la fin de cette décennie, le processus de production s'est sophistiqué avec l'organisation et l'entraînement d'équipes spécialisées dans l'écriture de schoolbooks. Dans le sillage de ces premières maisons d'éditions, d'autres se sont affirmées et sont devenues des puissances nationales et internationales jouant un rôle décisif aussi bien dans l'américanisation des énormes vagues d'immigrants qui sont arrivées dans ce pays, dès la moitié du XIXe siècle, que dans celle des peuples soumis à la domination militaire ou économique des EUA.

A questão da centralidade em São Paulo: o papel das associações de caráter empresarial

Dans cet article, nous envisageons traiter une série de questions concernant le contexte urbain de la ville de São Paulo. Notre objectif est d'identifier: a) comment s'organisent les principaux groupes privés en vue de situer le secteur tertiaire moderne; b) comment leur organisations font pression sur le pouvoir public afin d'obtenir des bénéfices d'infrastructure d'équipements urbains; c) quelles sont les réponses concrètes du pouvoir public; d) quels sont les principaux groupes sociaux, issus des classes populaires qui sont pourtant atteints par ce jeu d'intérêts.

Virasoro constraints and flavor-topology duality in QCD

We derive Virasoro constraints for the zero momentum part of the QCD-like partition functions in the sector of topological charge v. The constraints depend on the topological charge only through the combination N-f +betav/2 where the value of the Dyson index beta is determined by the reality type of the fermions. This duality between flavor and topology is inherited by the small-mass expansion of the partition function and all spectral sum rules of inverse powers of the eigenvalues of the Dirac operator. For the special case beta =2 but arbitrary topological charge the Virasoro constraints are solved uniquely by a generalized Kontsevich model with the potential V(X) = 1/X.

Federalismo e relações intergovernamentais no Brasil: a reforma de programas sociais

The article analyses the process of reform in four areas of social policies that affect directly the interests of sub-national governments: basic education, social housing programs, basic sanitation and health. As the study reveals, despite the varying degree of success achieved in the various policy initiatives and contrary to the expectations of the prevailing interpretations of the nature of Brazilian federalism, the federal government faced no insurmountable hurdles in implementing their reform agenda. The study aims at demonstrating that (i) in the absence of any constitutional mandatory requirement, the political autonomy of local governments - typical of federative States - actually enhances the veto power of local governments over policy initiatives proposed by the federal Executive branch. However, (ii) power resources available to the federal Executive branch - such as agenda definition and vetoing powers - in addition to control over resources that are essential to the political survival of the representatives increase the chances of success-of the federal government. Furthermore, (1999), (iii) the constitutional authority of Brazilian states is far more limited than that of the North-American states; (iv) the category federalism, however, is not sufficient to define the potential stability of specific policies, which depends upon how inter-governmental relations are structured in each particular policy. Specifically, (v) constitutional rules, legacies from previous policies and the political cycle frame the decision arenas in various ways, thus conditioning both the strategies and chances of success of the federative players.

Characterization of the reversible photoinduced optical changes in Sb-based glasses

Changes occurring in absorption coefficients when glasses in the SbPO4-WO3 binary system were irradiated by light, at the edge of the absorption band, were measured in real time. These glasses present good thermal and optical properties and photoinduced changes in the absorption coefficients are reversible by heat treatment around 150 degrees C. Subsequent recording/erasing cycles could be made without sample degradation. The sensitivity of the induced optical changes was studied for different wavelengths, light powers and energy of light dose exposures, and for different compositions of the glasses. The changes in the absorption coefficients of the glass samples were accompanied by a color change from yellow to blue, and were also characterized by visible spectroscopy. The color changes occurred through the entire volume of the glass (similar to 2 mm thickness) for the Ar-ion laser lines at the edge of the absorption band. (c) 2006 Elsevier B.V. All rights reserved.

Collisional semiclassical approximations in phase-space representation

The Gaussian wave-packet phase-space representation is used to show that the expansion in powers of a of the quantum Liouville propagator leads, in the zeroth-order term, to results close to those obtained in the statistical quasiclassical method of Lee and Scully in the Weyl-Wigner picture. It is also verified that, propagating the Wigner distribution along the classical trajectories, the amount of error is less than that coming from propagating the Gaussian distribution along classical trajectories.

A low-cost neurostimulator with accurate pulsed-current control

A constant-current stimulator for high-impedance loads using only low-cost standard high-voltage components Is presented. A voltage-regulator powers an oscillator built across the primary of a step-up transformer whose secondary supplies, after rectification, the high voltage to a switched current-mirror in the driving stage. Adjusting the regulated voltage controls the pulsed-current intensity. A prototype produces stimulus of amplitude and pulsewidth within 0 less than or equal to I-skin less than or equal to 20 mA and 50 mus less than or equal to T-pulse less than or equal to 1 ms, respectively. Pulse-repetition spans from 1 Hz to 10 Hz. Worst case ripple is 3.7% at I-skin = 1 mA. Overall consumption is 5.6 W at I-skin = 20 mA.