Wound healing of dehiscence defects following different root conditioning modalities: An experimental study in dogs

Objective: The purpose of this study was to investigate the periodontal healing pattern of dehiscence-type defects following different chemical root conditioning modalities. Materials and methods: Buccal osseous dehiscence defects were created on six teeth of seven dogs. After dental plaque accumulation, defects were treated with sterile saline solution (control group) or one chemical conditioning modality: citric acid (CA group), ethylenediaminetetraacetic acid (EDTA group), tetracycline (TTC group), citric acid + tetracycline (CA + TTC group), or tetracycline + citric acid (TTC + CA group). After 3 months of healing, clinical parameters were evaluated, and the animals were killed. Histological sections were processed, and a computer-assisted histometric analysis was used to evaluate the formation of new cementum, new bone, and epithelial apical migration. Results: All treatments yielded significant improvements in terms of probing depth decrease and clinical attachment level gain compared to baseline values; however, without significant differences among the groups (p > 0.05; one-way ANOVA). The highest amount of new cementum was noted in the EDTA group (3.72 ± 0.83 mm, 77.6 %), while the lowest amount of new bone was observed in the TTC group (0.7 ± 0.94 mm, 14.3 %). However, no statistically significant differences could be observed among the groups regarding epithelial apical migration, new cementum, and alveolar bone formation (p > 0.05). Conclusion: Chemical root surface conditioning did not promote any significant improvement in periodontal healing pattern of dehiscence-type defects in dogs. Clinical Relevance: Chemical root surface conditioning after surgical debridement did not promote positive or negative effects on periodontal healing pattern of dehiscence-type defects. © 2012 Springer-Verlag Berlin Heidelberg.

Role of the range of the dipole function in the classical dynamics of molecular dissociation

The dissociation dynamics of heteronuclear diatomic molecules induced by infrared laser pulses is investigated within the framework of the classical driven Morse oscillator. The interaction between the molecule and the laser field described in the dipole formulation is given by the product of a time-dependent external field with a position-dependent permanent dipole function. The effects of changing the spatial range of the dipole function in the classical dissociation dynamics of large ensembles of trajectories are studied. Numerical calculations have been performed for distinct amplitudes and carrier frequencies of the external pulses and also for ensembles with different initial energies. It is found that there exist a set of values of the dipole range for which the dissociation probability can be completely suppressed. The dependence of the dissociation on the dipole range is explained through the examination of the Fourier series coefficients of the dipole function in the angle variable of the free system. In particular, the suppression of dissociation corresponds to dipole ranges for which the Fourier coefficients associated with nonlinear resonances are null and the chaotic region in the phase space is reduced to thin layers. In this context, it is shown that the suppression of dissociation of heteronuclear molecules for certain frequencies of the external field is a consequence of the finite range of the corresponding permanent dipole. © 2013 American Physical Society.

Some dynamical properties of a classical dissipative bouncing ball model with two nonlinearities

Some dynamical properties for a bouncing ball model are studied. We show that when dissipation is introduced the structure of the phase space is changed and attractors appear. Increasing the amount of dissipation, the edges of the basins of attraction of an attracting fixed point touch the chaotic attractor. Consequently the chaotic attractor and its basin of attraction are destroyed given place to a transient described by a power law with exponent -2. The parameter-space is also studied and we show that it presents a rich structure with infinite self-similar structures of shrimp-shape. © 2013 Elsevier B.V. All rights reserved.

Sending classical information through relativistic quantum channels

We investigate how special relativity influences the transmission of classical information through quantum channels by evaluating the Holevo bound when the sender and the receiver are in (relativistic) relative motion. By using the spin degrees of freedom of spin-1/2 fermions to encode the classical information, we show that, for some configurations, the accessible information in the receiver can be increased when the spin detector moves fast enough. This is possible by allowing the momentum wave packet of one of the particles to be sufficiently wide while the momentum wave packets of other particles are kept relatively narrow. In this way, one can take advantage of the fact that boosts entangle the spin and momentum degrees of freedom of spin-1/2 fermions to increase the accessible information in the former. We close the paper with a discussion of how this relativistic quantum channel cannot in general be described by completely positive quantum maps. © 2013 American Physical Society.

Chaotic thermalization in classical gauge theories

We explore the idea that chaos concepts might be useful for understanding the thermalization in gauge theories. The SU(2) Higgs model is discussed as a prototype of system with gauge fields coupled to matter fields. Through the numerical solution of the equations of motion, we are able to characterize chaotic behavior via the corresponding Lyapunov exponent. Then it is demonstrated that the system's approach to equilibrium can be understood through direct application of the principles of Statistical Mechanics. © 2013 AIP Publishing LLC.

Repair bond strength of microhybrid, nanohybrid and nanofilled resin composites: Effect of substrate resin type, surface conditioning and ageing

Objectives: This study evaluated the microtensile bond strength (MTBS) of non-aged and aged resin-based composites (RBC) (nanohybrid and nanofilled) after two surface conditioning methods, repaired using the composite of the same kind or a microhybrid composite. Materials and methods: Nanohybrid (Tetric EvoCeram-TE) and nanofilled (Filtek Supreme-FS) RBC blocks (5 × 5 × 6 mm) (N = 128) were fabricated and randomly divided into two groups: (a) no ageing (control group) and (b) ageing (5.000 thermocycling, 5-55 °C). RBC surfaces were polished by up to 1,200-grit silicone carbide papers and conditioned with either (a) air abrasion with 30-μm SiO2 particles (CoJet Sand) for 4 s + silane coupling agent (ESPE-Sil) + adhesive resin (VisioBond) (n = 16) or (b) adhesive application only (Multilink A+B for TE; Adper ScotchBond 1XT for FS) (n = 16). In half of the groups, repair resin of the same kind with the RBC and, in the other half, a different kind of composite (microhybrid, Quadrant Anterior Shine-AS) with its corresponding adhesive (Quadrant UniBond) was used. The specimens were submitted to MTBS test (0.5 mm/min). Data were analysed using three-way ANOVA and Tukey's tests. Degree of conversion (DC) of non-aged and aged resin composites (TE, FS) (n = 3 per group) was measured by micro-Raman analyses. Results: RBC type (p = 0.001) and ageing affected the MTBS results significantly (p = 0.001). Surface conditioning type did not show significant difference (p = 0.726), but less number of pre-test failures was experienced with the CoJet system compared to adhesive resin application only. Repair strength on aged TE showed significantly less (p < 0.05) MTBS than for FS. FS repaired with the same kind of RBC and adhesive resin presented the highest cohesive failures (43 %). DC was higher for TE (71 %) than for FS (58 %) before ageing. Conclusion: On the aged RBCs, less favourable repair strength could be expected especially for nanohybrid composite. For repair actions, RBC surface conditioning could be accomplished with either adhesive resin application only or with CoJet system, providing that the latter resulted in less pre-test failures. Clinical relevance: Clinicians could condition the resin surface prior to repair or relayering with either CoJet system or adhesive resin application only, depending on the availability of the system. © 2012 Springer-Verlag Berlin Heidelberg.

Experimental research on the influence of the air humidity conditions in an air conditioning system

The factors that have influence on the energy consumption of a small air conditioning system that are worth mentioning are the efficiencies of the compressor, evaporator and condenser, the form that the refrigerant flow is controlled, the fan model used, and climatic conditions. Within the climate issue, an interesting factor is that the relative humidity when it comes to the effect that it causes, especially in the performance of the air condenser, which generally is not considered in the projects. This study aims to evaluate the influence of humidity on the coefficient of system performance (COP), seeking to quantify their influence when it happens. The tests were performed on a testing bench, mounted at the Laboratory for Energy Efficiency (LAMOTRIZ) UNESP-Campus Guaratinguetá. In the study, the wet bulb temperature was ranged, keeping the rotation of the scroll compressor with application of a frequency inverter in its best performance. The test bench is provided with a supervisory system of data collection that is also able to control all functions of the bench. In the results, there was a significant influence, particularly when comparing high humidity conditions with low humidity, noting that only over 65% relative humidity is that significant changes are observed in the COP of the system. © 2013 Elsevier Inc.

Dynamical properties for an ensemble of classical particles moving in a driven potential well with different time perturbation

We consider dynamical properties for an ensemble of classical particles confined to an infinite box of potential and containing a time-dependent potential well described by different nonlinear functions. For smooth functions, the phase space contains chaotic trajectories, periodic islands and invariant spanning curves preventing the unlimited particle diffusion along the energy axis. Average properties of the chaotic sea are characterised as a function of the control parameters and exponents describing their behaviour show no dependence on the perturbation functions. Given invariant spanning curves are present in the phase space, a sticky region was observed and show to modify locally the diffusion of the particles. © 2013 Elsevier B.V.

Conditioning factors of the success of population policies: the cases of El Salvador and Costa Rica

Includes bibliography

Contribuição diferencial do hipocampo ventral e do complexo amidalóide na modulação de respostas defensivas inatas e condicionadas de camundongos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Type-II defects in integrable classical field theories

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

Discriminação com três tipos de contingências supressivas: extinção, punição e extinção + punição

Nos estudos sobre controle de estímulos é predominantemente utilizado reforçamento em SD e Extinção em SΔ para se estabelecer uma discriminação simples. Poucos estudos utilizaram Punição em SΔ para estabelecer tal responder diferencial, contudo, a maioria desses produziu uma aprendizagem mais rápida do que a tradicionalmente obtida apenas com extinção. Quando este tipo de procedimento foi utilizado, em geral, o choque elétrico foi usado como punidor. Carvalho Neto e Cols. vêm testando um jato de ar quente (JAQ) como estímulo aversivo alternativo e até agora obtiveram êxito em contextos supressivos (apresentação contingente e não contingente) e fortalecedores negativos (fuga e esquiva). Carvalho Neto e Farias (2006) e Carvalho Neto e Costa (2008) testaram o JAQ como supressor diante de SΔ buscando produzir uma discriminação claro/escuro e nesses estudos as contingências punitivas foram mais eficazes do que a tradicional. Contudo, foram identificados alguns problemas metodológicos nesses trabalhos que limitariam suas conclusões. O presente trabalho buscou controlar algumas dessas variáveis, em especial, a passagem do tempo fixo e o tipo de esquema em vigor. Foram utilizados seis ratos machos divididos em três condições: Extinção, Punição e Extinção+Punição. Foi utilizada uma Caixa de Condicionamento Operante adaptada ao JAQ. O procedimento para as três condições foi o mesmo, alterando-se apenas as sessões de Treino Discriminativo (reforçamento em SD para todas as condições e durante SΔ: Extinção para a condição Extinção, Punição para a condição Punição e Punição+Extinção para a condição Punição+Extinção). Os sujeitos nas condições em que a punição foi usada mostraram um responder discriminado, enquanto que a condição Extinção falhou em produzir tal responder, indicando que o uso do controle aversivo foi mais eficiente que o procedimento tradicional.

Efeitos da punição sobre respostas mantidas em diferentes sistemas econômicos (aberto e fechado) em Rattus norvegicus

Os sistemas econômicos comportamentais são definidos como diferentes relações existentes entre o consumo e a forma como o organismo o obtém. Existem tipicamente dois tipos de sistemas econômicos: a economia fechada, na qual a porção alimentar diária do sujeito só pode ser adquirida dentro da sessão experimental; e a economia aberta, na qual, além desta, o sujeito recebe uma complementação alimentar após a sessão. Este estudo teve como objetivo averiguar os efeitos da punição positiva sobre respostas mantidas em diferentes sistemas econômicos. Foram realizados dois experimentos. No Experimento 1 dois Rattus norvegicus, machos, privados de água por 24 horas, divididos entre as duas economias: A1 (aberta) e F1 (fechada). O estímulo aversivo foi um Jato de ar-quente (JAQ) por 5 segundos e contingente a cada resposta de pressão à barra (RPB). Cada sujeito passou pelas seguintes fases: Nível Operante, Modelagem da RPB, Fortalecimento em CRF, Punição e Recondicionamento. No Experimento 2 foram utilizados quatro Rattus norvegicus, Wistar, machos, privados de água por 24 horas, divididos em duas duplas: FAF (Fechada/Aberta/Fechada) e AFA (Aberta/Fechada/Aberta). O estímulo aversivo foi um choque de 1.3mA, por cinco segundos e contingente a cada RPB. Durante o experimento, ambos passaram pelas seguintes fases: Nível Operante, Modelagem da RPB, Fortalecimento em FR10, Punição (em uma economia), Recondicionamento, Punição (em uma economia diferente da anterior), outro Recondicionamento, por fim, uma sessão de Punição na economia inicial. Os dados dos dois Experimentos demonstraram uma supressão média no responder durante as fases de Punição em comparação com as fases de Fortalecimento/Recondicionamento, em ambas as economias e em todos os sujeitos: 48,7%(F1); 96,6%(A1); 99,9%, 99,9% e 89,8%(FAF1); 93,2%, 99,4% e 84,8% (FAF2); 99,8%, 83,6% e 95% (AFA1); 92,3%, 90,9% e 91,6% (AFA2). Estes resultados demonstram que tanto o choque quanto o JAQ funcionaram como estímulos aversivos, porém a diferença entre as duas economias foi maior nos sujeitos que tiveram suas respostas punidas com o JAQ.

Supressão condicionada com diferentes estímulos aversivos: choque elétrico e jato de ar quente

Um estímulo neutro, quando pareado a um estímulo aversivo incondicional, adquire a função de aversivo (condicional) e, indiretamente, também é capaz de suprimir operantes. Tal fenômeno foi denominado de “supressão condicionada” e está principalmente relacionado a certos estados emocionais, como a ansiedade. A literatura mostra que, em geral, o estímulo aversivo incondicional utilizado se restringe ao choque elétrico. Foram poucos os estímulos aversivos alternativos testados que se mostraram eficazes. Entretanto, mesmo utilizando o choque como aversivo incondicional, há outras variáveis que podem influenciar diretamente o surgimento do fenômeno. Este trabalho teve por objetivo examinar e comparar a produção de supressão condicionada com dois tipos de estímulos aversivos: jato de ar quente (JAQ) e choque elétrico. Foram utilizados 4 ratos albinos (Rattus norvegicus, Wistar). Duas Caixas de Condicionamento Operante, uma utilizada para o estímulo choque e a outra adaptada para o JAQ, serviram de equipamentos. Os sujeitos foram divididos em duplas e expostos a pareamentos de um estímulo neutro com diferentes estímulos aversivos: Som+JAQ (Sujeito J1 e J2) e Som+Choque elétrico (Sujeito C1 e C2). Os dados mostram que os sujeitos expostos ao delineamento com choque apresentaram uma razão supressiva total (0,0) após dois (C1) ou três (C2) pareamentos, o que significa que o som tornou-se um aversivo condicional capaz de suprimir integralmente a freqüência da resposta de pressão à barra (RPB). Já para os sujeitos expostos ao procedimento com JAQ ocorreu somente supressão parcial da RPB frente ao som, sendo necessárias no mínimo oito (J1) e sete (J2) pareamentos para que os valores da razão supressiva chegassem a 0,5 (J1) e 0,2 (J2). As análises de outras respostas mostraram que em média ocorreu um aumento de 83,3% (J1) e 275% (J2) na frequência das respostas exploratórias durante a apresentação do som, nas sessões de pareamento com o JAQ, comparado com a apresentação do som nas sessões de habituação, enquanto que para os sujeitos que foram expostos ao pareamento com o choque houve uma supressão de 44,2% (C1) e 57,1% (C2) em tais respostas. Tais dados permitem concluir que a supressão ocasionada pelo pareamento do som+choque atingiu outras classes de respostas, diferente do som pareado com o JAQ. A supressão ocasionada pelo JAQ parece ter sido conseqüência da emissão de respostas exploratórias. É possível que o parâmetro intensidade do JAQ, utilizado neste experimento, tenha sido a variável responsável por tais resultados. Futuras pesquisas poderão elucidar estes dados.

Comparison of Physicochemical Surface Conditioning Methods for Adhesion of bis-GMA Resin Cement to Particulate Filler Composite and Surface Characterization

This study compared the effect of physicochemical surface conditioning methods on the adhesion of bis-GMA-based resin cement to particulate filler composite (PFC) used for indirect dental restorations. PFC blocks (N (block)=54, n (block)=9 per group) were polymerized and randomly subjected to one of the following surface conditioning methods: a) No conditioning (Control-C), b) Hydrofluoric acid (HF)etching for 60s (AE60), c) HF for 90s (AE90), d) HF for 120s (AE120), e) HF for 180s (AE180), and f) air-abrasion with 30 mu m silica-coated alumina particles (AB). The conditioned surfaces were silanized with an MPS silane, and an adhesive resin was applied. Resin composite blocks were bonded to PFC using resin cement and photo-polymerized. PFC-cement-resin composite blocks were cut under coolant water to obtain bar specimens (1mmx0.8mm). Microtensile bond strength test (mu TBS)was performed in a universal testing machine (1mm/min). After debonding, failure modes were classified using stereomicroscopy. Surface characterization was performed on a set of separate specimen surfaces using Scanning Electron Microscopy (SEM), X-Ray Dispersive Spectroscopy (XDS), X-Ray Photoelectron Spectroscopy (XPS), and Fourier Transform-Raman Spectroscopy (FT-RS). Mean mu TBS (MPa) of C (35.6 +/- 4.9) was significantly lower than those of other groups (40.2 +/- 5.6-47.4 +/- 6.1) (p<0.05). The highest mu TBS was obtained in Group AB (47.4 +/- 6.1). Prolonged duration of HF etching increased the results (AE180: 41.9 +/- 7), but was not significantly different than that of AB (p>0.05). Failure types were predominantly cohesive in PFC (34 out of 54) followed by cohesive failure in the cement (16 out of 54). Degree of conversion (DC) of the PFC was 63 +/- 10%. SEM analysis showed increased irregularities on PFC surfaces with the increased etching time. Chemical surface analyses with XPS and FT-RS indicated 11-70% silane on the PFC surfaces that contributed to improved bond strength compared to Group C that presented 5% silane, which seemed to be a threshold. Group AB displayed 83% SiO2 and 17% silane on the surfaces.