986 resultados para 3 dB CP bandwidth


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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70SiO2 - 30HfO2 planar waveguides, activated by Er3+ concentration ranging from 0.3 to 1 mol%, were prepared by solgel route, using dip-coating deposition on silica glass substrates. The waveguides showed high densification degree, effective intermingling of the two components of the film, and uniform surface morphology. Propagation losses of about 1 dB/cm were measured at 632.8 nm. When pumped with 987 nm or 514.5 nm continuous-wave laser light, the waveguides showed the 4I 13/2→4I15/2 emission band with a bandwidth of 48 nm. The spectral features were found independent both on erbium content and excitation wavelength. The 4I13/2 level decay curves presented a single exponential profile, with a lifetime between 2.9-5.0 ms, depending on the erbium concentration.

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Aim: There is little information considering the framework association between cast clasps and attachments. The aim of this study was to evaluate the retention strength of frameworks match circumferential clasps and extra resilient attachment cast in three different alloys (cobalt-chromium, nickel-chromium titanium and commercially pure titanium), using two undercut (0.25 and 0.75 mm) and considering different period of time (0, 1/2, 1, 2, 3, 4 and 5 years). Methods: Using two metallic matrices, representing a partially edentulous mandibular right hemiarch with the first molar crown, canine root and without premolars, 60 frameworks were fabricated. Three groups (n = 20) of each metal were cast and each group was divided into two subgroups (n = 10), corresponding the molar undercut of 0.25 mm and 0.75 mm. The nylon male was positioned at the matrix and attached to the acrylic resin of the prosthetic base. The samples were subjected to an insertion and removal test under artificial saliva environment. Results: The data were analyzed and compared with ANOVAs and Tukey's test at 95% of probability. The groups cast in cobaltchromium and nickel-chromium-titanium had the highest mean retention strength (5.58 N and 6.36 N respectively) without significant difference between them, but statistically different from the group cast in commercially pure titanium, which had the lowest mean retention strength in all the periods (3.46 N). The association frameworks using nickel-chromium-titanium and cobalt-chromium could be used with 0.25 mm and 0.75 mm of undercut, but the titanium samples seems to decrease the retention strength, mainly in the 0.75 mm undercut. The circumferential clasps cast in commercially pure titanium used in 0.75 mm undercuts have a potential risk of fractures, especially after the 2nd year of use. Conclusion: This in vitro study showed that the framework association between cast clasp and an extra resilient attachment are suitable to the three metals evaluated, but strongly suggest extra care with commercially pure titanium in undercut of 0.75 mm. Clinical significance: Frameworks fabricated in Cp Ti tend to decrease in retentive strength over time and have a potential risk of fracture in less than 0.75 mm of undercut.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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This study aims to characterize the microstructure of the complex phase steel (CP). Using the conventional and colored metallographic analysis with 3% Nital etchant, sodium metabisulfite 10% and LePera. Techniques were applied in this work of optical microscopy, using, besides the lighting in bright field, dark field illumination of the reverse contrast in bright field illumination, the method of polarized light, which generates colorful contrast, providing a complementary identification phases present in the microstructure, and the system by differential interference contrast (DIC). The results obtained by metallography CP indicates that the steel has a microstructure composed of ferrite, retained austenite, bainite and martensite and precipitates arranged in a refined and complex morphology. Besides bright field illumination others' optical microscopy's techniques such as dark field illumination were applied.

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We report the first demonstration of mid-infrared supercontinuum generation in As2Se3 chalcogenide microwires with the added advantage of using low energy pulses. The generated SC covers two octaves of bandwidth from 1.1 µm to 4.4 µm at -30 dB. This exceeds the broadest reported SC bandwidth in As2Se3 microwires by a factor of 3.5. The microwire geometry and pumping conditions are the key parameters in generating the 3.3 µm bandwidth while using a low pump pulse energy of 500 pJ.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Assuming that neutrinos are Majorana particles, in a three-generation framework, current and future neutrino oscillation experiments can determine six out of the nine parameters which fully describe the structure of the neutrino mass matrix. We try to clarify the interplay among the remaining parameters, the absolute neutrino mass scale and two CP violating Majorana phases, and how they can be accessed by future neutrinoless double beta (0vυββ) decay experiments, for the normal as well as for the inverted order of the neutrino mass spectrum. Assuming the oscillation parameters to be in the range presently allowed by atmospheric, solar, reactor, and accelerator neutrino experiments, we quantitatively estimate the bounds on m 0, the lightest neutrino mass, that can be inferred if the next generation 0υββ decay experiments can probe the effective Majorana mass (m ee) down to ∼1 meV. In this context we conclude that in the case that neutrinos are Majorana particles, (a) if m 0≳300 meV, i.e., within the range directly attainable by future laboratory experiments as well as astrophysical observations, then m ee≳30 meV must be observed, (b) if m 0 ≤ 300 meV, results from future 0υββ decay experiments combined with stringent bounds on the neutrino oscillation parameters, especially the solar ones, will place much stronger limits on the allowed values of m 0 than these direct experiments. For instance, if a positive signal is observed around m ee = 10 meV, we estimate 3≲m 0/meV≲65 at 95% C.L.; on the other hand, if no signal is observed down to m ee = 10 meV, then m 0≲55 meV at 95% C.L.

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

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A complete analysis of the sensitivity to new Hbb̄ couplings from the process e+e- → bb̄vv̄ at the next generation of linear colliders was performed. These new couplings were predicted by many extensions of the Standard Model. The results are comparable to the study performed previously where a global fit analysis for L=500 fb-1 and √s=500 GeV resulted in a relative accuracy of 2.2% in the gHbb Yukawa coupling.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)