166 research outputs found

    Effect of thermal cycling on denture base and autopolymerizing reline resins

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    OBJECTIVE: This study evaluated the fracture toughness (FT) of denture base and autopolymerizing reline resins, with and without thermocycling (T). MATERIAL AND METHODS: Specimens of each material (denture base acrylic resin - Lucitone 550 - L; autopolymerizing reline resins - Ufi Gel Hard-UH, Tokuyama Rebase II-TR, New Truliner- NT and Kooliner-K), were produced, notched and divided into two groups (n=10): CG (control group of autopolymerizing reline resins and L): FT tests were performed after polymerization; TG (thermocycled group): FT tests were performed after T (5ºC and 55ºC for 5,000 cycles). RESULTS: Results (MPa.m((1/2))) were analyzed by two-way ANOVA and Tukey's test (p=0.05). L exhibited the highest FT mean values in both groups (CG - 2.33; TG - 2.17). For the CG groups, NT showed the highest FT (1.64) among the autopolymerizing reline resins, and K the lowest (1.04). After T, when the autopolymerizing reline resins were compared, a statistically significant difference in FT was found only between the NT (1.46) and TR (1.00). CONCLUSIONS: Thermocycling increased the FT of K and did not influence the FT of L, UH, TR and NT

    Predicting Landscape-Genetic Consequences of Habitat Loss, Fragmentation and Mobility for Multiple Species of Woodland Birds

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    Inference concerning the impact of habitat fragmentation on dispersal and gene flow is a key theme in landscape genetics. Recently, the ability of established approaches to identify reliably the differential effects of landscape structure (e.g. land-cover composition, remnant vegetation configuration and extent) on the mobility of organisms has been questioned. More explicit methods of predicting and testing for such effects must move beyond post hoc explanations for single landscapes and species. Here, we document a process for making a priori predictions, using existing spatial and ecological data and expert opinion, of the effects of landscape structure on genetic structure of multiple species across replicated landscape blocks. We compare the results of two common methods for estimating the influence of landscape structure on effective distance: least-cost path analysis and isolation-by-resistance. We present a series of alternative models of genetic connectivity in the study area, represented by different landscape resistance surfaces for calculating effective distance, and identify appropriate null models. The process is applied to ten species of sympatric woodland-dependant birds. For each species, we rank a priori the expectation of fit of genetic response to the models according to the expected response of birds to loss of structural connectivity and landscape-scale tree-cover. These rankings (our hypotheses) are presented for testing with empirical genetic data in a subsequent contribution. We propose that this replicated landscape, multi-species approach offers a robust method for identifying the likely effects of landscape fragmentation on dispersal

    Effects of air abrasion with alumina or glass beads on surface characteristics of CAD/CAM composite materials and the bond strength of resin cements

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    ABSTRACT Objective The study aimed to evaluate effects of air abrasion with alumina or glass beads on bond strengths of resin cements to CAD/CAM composite materials. Material and Methods CAD/CAM composite block materials [Cerasmart (CS) and Block HC (BHC)] were pretreated as follows: (a) no treatment (None), (b) application of a ceramic primer (CP), (c) alumina-blasting at 0.2 MPa (AB), (d) AB followed by CP (AB+CP), and (e) glass-beads blasting at 0.4 MPa (GBB) followed by CP (GBB+CP). The composite specimens were bonded to resin composite disks using resin cements [G-CEM Cerasmart (GCCS) and ResiCem (RC)]. The bond strengths after 24 h (TC 0) and after thermal cycling (TC 10,000 at 4–60°C) were measured by shear tests. Three-way ANOVA and the Tukey compromise post hoc tests were used to analyze statistically significant differences between groups (α=0.05). Results For both CAD/CAM composite materials, the None group exhibited a significant decrease in bond strength after TC 10,000 (p0.05). The AB+CP group showed a significantly higher bond strength after TC 10,000 than did the AB group for RC (p<0.05), but not for GCCS. The GBB+CP group showed the highest bond strength for both thermal cyclings (p<0.05). Conclusions Air abrasion with glass beads was more effective in increasing bond durability between the resin cements and CAD/CAM composite materials than was using an alumina powder and a CP

    On the Estimation Stability of Efficiency and Economies of Scale in Microfinance Institutions

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    This paper uses a panel data set of microfinance institutions (MFI) across the world to compare several identification strategies of cost efficiency and economies of scale. Concretely, we contrast the non-parametric Data Envelopment Analysis (DEA) with the Stochastic Frontier Analysis (SFA) and a distribution-free identification based on time-invariant heterogeneity estimates. Furthermore, we analyze differences of production functions across regions and investigate the relevance of accounting for unobserved heterogeneity across countries. The results suggest that efficiency rankings of MFIs are robust across identification strategies, but highlight the relevance of accounting for unobserved heterogeneity. We further find substantial economies of scale for a pure financial production process. However, accounting for the multi-dimensional production process of MFIs by including a measure of outreach lowers the estimated extent of economies of scale for the parametric estimations, suggesting that producing outreach creates high transaction costs and requires exploitation of local knowledge

    Improving Cosmological Constraints from Galaxy Cluster Number Counts with CMB-cluster-lensing Data: Results from the SPT-SZ Survey and Forecasts for the Future

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    We show the improvement to cosmological constraints from galaxy cluster surveys with the addition of cosmic microwave background (CMB)-cluster lensing data. We explore the cosmological implications of adding mass information from the 3.1 sigma detection of gravitational lensing of the CMB by galaxy clusters to the Sunyaev-Zel'dovich (SZ) selected galaxy cluster sample from the 2500 deg(2) SPT-SZ survey and targeted optical and X-ray follow-up data. In the ACDM model, the combination of the cluster sample with the Planck power spectrum measurements prefers sigma(8) (Omega(m)/0.3)(0.5) = 0.831 +/- 0.020. Adding the cluster data reduces the uncertainty on this quantity by a factor of 1.4, which is unchanged whether the 3.1 sigma CMB-cluster lensing measurement is included or not. We then forecast the impact of CMB-cluster lensing measurements with future cluster catalogs. Adding CMB-cluster lensing measurements to the SZ cluster catalog of the ongoing SPT-3G survey is expected to improve the expected constraint on the dark energy equation of state w by a factor of 1.3 to sigma(w) = 0.19. We find the largest improvements from CMB-cluster lensing measurements to be for sigma(8), where adding CMB-cluster lensing data to the cluster number counts reduces the expected uncertainty on sigma(8) by respective factors of 2.4 and 3.6 for SPT-3G and CMB-S4

    Searching for Anisotropic Cosmic Birefringence with Polarization Data from SPTpol

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    We present a search for anisotropic cosmic birefringence in 500 deg2^2 of southern sky observed at 150 GHz with the SPTpol camera on the South Pole Telescope. We reconstruct a map of cosmic polarization rotation anisotropies using higher-order correlations between the observed cosmic microwave background (CMB) EE and BB fields. We then measure the angular power spectrum of this map, which is found to be consistent with zero. The non-detection is translated into an upper limit on the amplitude of the scale-invariant cosmic rotation power spectrum, L(L+1)CLαα/2π<0.10×104L(L+1)C_L^{\alpha\alpha}/2\pi < 0.10 \times 10^{-4} rad2^2 (0.033 deg2^2, 95% C.L.). This upper limit can be used to place constraints on the strength of primordial magnetic fields, B1Mpc<17nGB_{1 \rm Mpc} < 17 {\rm nG} (95% C.L.), and on the coupling constant of the Chern-Simons electromagnetic term gaγ<4.0×102/HIg_{a\gamma} < 4.0 \times 10^{-2}/H_I (95% C.L.), where HIH_I is the inflationary Hubble scale. For the first time, we also cross-correlate the CMB temperature fluctuations with the reconstructed rotation angle map, a signal expected to be non-vanishing in certain theoretical scenarios, and find no detectable signal. We perform a suite of systematics and consistency checks and find no evidence for contamination.Comment: 17 pages, 7 figures - new subsection on non-Gaussian foregrounds, conclusions unchanged - updated to match published version on PR

    A Measurement of the CMB Temperature Power Spectrum and Constraints on Cosmology from the SPT-3G 2018 TT/TE/EE Data Set

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    We present a sample-variance-limited measurement of the temperature power spectrum (TTTT) of the cosmic microwave background (CMB) using observations of a  ⁣1500deg2\sim\! 1500 \,\mathrm{deg}^2 field made by SPT-3G in 2018. We report multifrequency power spectrum measurements at 95, 150, and 220GHz covering the angular multipole range 750<3000750 \leq \ell < 3000. We combine this TTTT measurement with the published polarization power spectrum measurements from the 2018 observing season and update their associated covariance matrix to complete the SPT-3G 2018 TT/TE/EETT/TE/EE data set. This is the first analysis to present cosmological constraints from SPT TTTT, TETE, and EEEE power spectrum measurements jointly. We blind the cosmological results and subject the data set to a series of consistency tests at the power spectrum and parameter level. We find excellent agreement between frequencies and spectrum types and our results are robust to the modeling of astrophysical foregrounds. We report results for Λ\LambdaCDM and a series of extensions, drawing on the following parameters: the amplitude of the gravitational lensing effect on primary power spectra ALA_\mathrm{L}, the effective number of neutrino species NeffN_{\mathrm{eff}}, the primordial helium abundance YPY_{\mathrm{P}}, and the baryon clumping factor due to primordial magnetic fields bb. We find that the SPT-3G 2018 T/TE/EET/TE/EE data are well fit by Λ\LambdaCDM with a probability-to-exceed of 15%15\%. For Λ\LambdaCDM, we constrain the expansion rate today to H0=68.3±1.5kms1Mpc1H_0 = 68.3 \pm 1.5\,\mathrm{km\,s^{-1}\,Mpc^{-1}} and the combined structure growth parameter to S8=0.797±0.042S_8 = 0.797 \pm 0.042. The SPT-based results are effectively independent of Planck, and the cosmological parameter constraints from either data set are within <1σ<1\,\sigma of each other. (abridged)Comment: 35 Pages, 17 Figures, 11 Table

    Performance and characterization of the SPT-3G digital frequency-domain multiplexed readout system using an improved noise and crosstalk model

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    The third generation South Pole Telescope camera (SPT-3G) improves upon its predecessor (SPTpol) by an order of magnitude increase in detectors on the focal plane. The technology used to read out and control these detectors, digital frequency-domain multiplexing (DfMUX), is conceptually the same as used for SPTpol, but extended to accommodate more detectors. A nearly 5x expansion in the readout operating bandwidth has enabled the use of this large focal plane, and SPT-3G performance meets the forecasting targets relevant to its science objectives. However, the electrical dynamics of the higher-bandwidth readout differ from predictions based on models of the SPTpol system. To address this, we present an updated derivation for electrical crosstalk in higher-bandwidth DfMUX systems, and identify two previously uncharacterized contributions to readout noise. The updated crosstalk and noise models successfully describe the measured crosstalk and readout noise performance of SPT-3G, and suggest improvements to the readout system for future experiments using DfMUX, such as the LiteBIRD space telescope

    Constraints on Λ\LambdaCDM Extensions from the SPT-3G 2018 EEEE and TETE Power Spectra

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    We present constraints on extensions to the Λ\LambdaCDM cosmological model from measurements of the EE-mode polarization auto-power spectrum and the temperature-EE-mode cross-power spectrum of the cosmic microwave background (CMB) made using 2018 SPT-3G data. The extensions considered vary the primordial helium abundance, the effective number of relativistic degrees of freedom, the sum of neutrino masses, the relativistic energy density and mass of a sterile neutrino, and the mean spatial curvature. We do not find clear evidence for any of these extensions, from either the SPT-3G 2018 dataset alone or in combination with baryon acoustic oscillation and \textit{Planck} data. None of these model extensions significantly relax the tension between Hubble-constant, H0H_0, constraints from the CMB and from distance-ladder measurements using Cepheids and supernovae. The addition of the SPT-3G 2018 data to \textit{Planck} reduces the square-root of the determinants of the parameter covariance matrices by factors of 1.32.01.3 - 2.0 across these models, signaling a substantial reduction in the allowed parameter volume. We also explore CMB-based constraints on H0H_0 from combined SPT, \textit{Planck}, and ACT DR4 datasets. While individual experiments see some indications of different H0H_0 values between the TTTT, TETE, and EEEE spectra, the combined H0H_0 constraints are consistent between the three spectra. For the full combined datasets, we report H0=67.49±0.53kms1Mpc1H_0 = 67.49 \pm 0.53\,\mathrm{km\,s^{-1}\,Mpc^{-1}}, which is the tightest constraint on H0H_0 from CMB power spectra to date and in 4.1σ4.1\,\sigma tension with the most precise distance-ladder-based measurement of H0H_0. The SPT-3G survey is planned to continue through at least 2023, with existing maps of combined 2019 and 2020 data already having 3.5×\sim3.5\times lower noise than the maps used in this analysis.Comment: Submitted to PRD; 19 pages, 7 figure
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