Experimental novel silane system in adhesion promotion between dental resin and pretreated titanium. Part II: Effect of long-term water storage: Rapid communication

In this study we have assessed the effect of long-term water storage at 37°C on silane-aided adhesion promotion. Five experimental silane blends were evaluated as adhesion-promoters. First, five functional organosilane monomers (silicon esters), 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, tetrakis-(2-methacryloxyethoxy)silane and bis-[3-(triethoxysilyl)propyl]tetrasulfide, were diluted to 1% (v/v) in 95% ethanol and blended with a non-functional cross-linking silane, bis-1,2-(triethoxysilyl)ethane (1%). A commercially available pre-activated silane product was used as the control. After activation by hydrolysis, each primer blend was applied to silica-coated Ti coupons. Stubs of experimental bis-phenol-A-diglycidyldimethacrylate (bis-GMA)-based resin were bonded by photo-polymerization onto the pretreated Ti coupons. Half of the specimens were stored in deionized water for 6 months and half for 12 months. The primer containing 3-acryloxypropyltrimethoxysilane and bis-1,2-(triethoxysilyl)ethane produced significantly higher shear bond strengths than the control silane and other experimental silane primers after both periods of storage. © 2010 The Author(s).published_or_final_versionSpringer Open Choice, 01 Dec 201

Enhanced resin-composite bonding to zirconia framework after pretreatment with selected silane monomers

Objective: To evaluate the effect of five experimental silane monomer primers in vitro on the shear bond strength of a phosphate ester resin-composite cement bonded to a silicatized zirconia framework. Methods: A total of 144 planar zirconia (Procera AllZircon) specimens were subjected to tribochemical silica treatment, randomly divided into 12 sub-groups (n = 12), and silanized with 1.0% (v/v) activated solutions of 3-acryloxypropyltrimethoxysilane, 3 glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, styrylethyltrimethoxysilane, and 3-isocyanatopropyltriethoxysilane, which had been prepared in 95% ethanol (pH 4.5). A ready-to-use 3- methacryloxypropyltrimethoxysilane (RelyX™ Ceramic Primer) was used as the control. One resincomposite cement (RelyX™ Unicem) stub was bonded to each silicatized and silanized zirconia specimen. Half of the specimen groups were dry-tested and half were thermo-cycled at 6000 cycles between 5 °C and 55 °C, with a constant dwelling time of 30 s. The shear bond strengths of the cement stubs bonded to zirconia were measured using a universal testing machine using a constant cross-head speed of 1 mm/min. The silane primer activation was evaluated using Fourier-transform infrared spectroscopy. Results: The highest shear bond strength was obtained for 3- acryloxypropyltrimethoxysilane in dry storage, 11.7 MPa (SD, 2.3 MPa) and after thermo-cycling 17.6 (4.1) MPa for glycidoxypropyltrimethoxysilane. The lowest shear bond strength values were obtained with control silane: in dry storage, 4.5 (1.3) MPa, after thermo-cycling 6.5 (2.6) MPa. Thermo-cycling increased the bond strengths significantly (ANOVA, p < 0.001) and differently for each type of silane (ANOVA, p < 0.001). Significance: Silanization with five experimental silane primers in vitro produced significantly greater shear bond strengths than the ready-to-use control silane. © 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.postprin

Experimental novel silane system in adhesion promotion between dental resin and pretreated titanium

Five silane blends were evaluated as experimental adhesion-promoter primers. First, five organosilane monomers (silicon esters), 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, tetrakis-(2-ethyloxyethoxy)silane and bis-[3-(triethoxysilyl)propyl]tetrasulfide, were diluted to 1% (v/v) and blended with a non-functional cross-linking silane, 1,2-bis-(triethoxysilyl)ethane (1%), in 95% ethanol. After activation, each blend was applied to silica-coated Ti coupons. A resin based on bis-phenol-A-diglycidyldimethacrylate was then bonded and photo-polymerized as stubs to the pretreated Ti coupons. Half of the specimens were stored in dry conditions and half were artificially aged by thermo-cycling. The primers containing 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltrimethoxysilane produced significantly higher shear bond strength values than the control silane, a standard pre-activated product used in clinical dentistry. © Springer Science+Business Media B.V. 2010.published_or_final_versionSpringer Open Choice, 01 Dec 201

Bose-Einstein Condensation of Excitons in Bilayer Electron Systems

An ordered state of electrons in solids in which excitons condense was proposed many years ago as a theoretical possibility but has, until recently, never been observed. We review recent studies of semiconductor bilayer systems that provide clear evidence for this phenomenon and explain why exciton condensation in the quantum Hall regime, where these experiments were performed, is as likely to occur in electron-electron bilayers as in electron-hole bilayers. In current quantum Hall exciton condensates, disorder induces mobile vortices that flow in response to a supercurrent and limit the extremely large bilayer counterflow conductivity.Comment: 19 pages including 4 figure

Quantifying Selective Reporting and the Proteus Phenomenon for Multiple Datasets with Similar Bias

Meta-analyses play an important role in synthesizing evidence from diverse studies and datasets that address similar questions. A major obstacle for meta-analyses arises from biases in reporting. In particular, it is speculated that findings which do not achieve formal statistical significance are less likely reported than statistically significant findings. Moreover, the patterns of bias can be complex and may also depend on the timing of the research results and their relationship with previously published work. In this paper, we present an approach that is specifically designed to analyze large-scale datasets on published results. Such datasets are currently emerging in diverse research fields, particularly in molecular medicine. We use our approach to investigate a dataset on Alzheimer's disease (AD) that covers 1167 results from case-control studies on 102 genetic markers. We observe that initial studies on a genetic marker tend to be substantially more biased than subsequent replications. The chances for initial, statistically non-significant results to be published are estimated to be about 44% (95% CI, 32% to 63%) relative to statistically significant results, while statistically non-significant replications have almost the same chance to be published as statistically significant replications (84%; 95% CI, 66% to 107%). Early replications tend to be biased against initial findings, an observation previously termed Proteus phenomenon: The chances for non-significant studies going in the same direction as the initial result are estimated to be lower than the chances for non-significant studies opposing the initial result (73%; 95% CI, 55% to 96%). Such dynamic patters in bias are difficult to capture by conventional methods, where typically simple publication bias is assumed to operate. Our approach captures and corrects for complex dynamic patterns of bias, and thereby helps generating conclusions from published results that are more robust against the presence of different coexisting types of selective reporting

Exciton Condensation and Perfect Coulomb Drag

Coulomb drag is a process whereby the repulsive interactions between electrons in spatially separated conductors enable a current flowing in one of the conductors to induce a voltage drop in the other. If the second conductor is part of a closed circuit, a net current will flow in that circuit. The drag current is typically much smaller than the drive current owing to the heavy screening of the Coulomb interaction. There are, however, rare situations in which strong electronic correlations exist between the two conductors. For example, bilayer two-dimensional electron systems can support an exciton condensate consisting of electrons in one layer tightly bound to holes in the other. One thus expects "perfect" drag; a transport current of electrons driven through one layer is accompanied by an equal one of holes in the other. (The electrical currents are therefore opposite in sign.) Here we demonstrate just this effect, taking care to ensure that the electron-hole pairs dominate the transport and that tunneling of charge between the layers is negligible.Comment: 12 pages, 4 figure

More advanced Alzheimer's disease may be associated with a decrease in cerebrospinal fluid pressure

In a recent article, elevated cerebrospinal fluid pressure (CSFP) consistent with very early normal pressure hydrocephalus (NPH), was found in a small subset of Alzheimer's disease (AD) patients (possible AD-NPH hybrids) enrolled in a clinical trial for chronic low-flow cerebrospinal fluid drainage. Also in the same study, was another interesting finding that merits further discussion: a substantial proportion of AD patients had very low CSFP. Based on the characteristics of these subjects, we hypothesize that more advanced AD may be associated with a decrease in CSFP. Reduced CSFP among a group of AD patients could provide a clue towards a better understanding of the high rate of comorbidity reported between AD and glaucoma since it has been shown that mean CSFP is lower in subjects with primary open-angle glaucoma. This could result in an abnormally high trans-lamina cribrosa pressure difference and lead to glaucomatous damage

Automatic analysis of bronchus-artery dimensions to diagnose and monitor airways disease in cystic fibrosis

Background:Cystic fibrosis (CF) lung disease is characterised by progressive airway wall thickening and widening. We aimed to validate an artificial intelligence-based algorithm to assess dimensions of all visible bronchus-artery (BA) pairs on chest CT scans from patients with CF.Methods:The algorithm fully automatically segments the bronchial tree; identifies bronchial generations; matches bronchi with the adjacent arteries; measures for each BA-pair bronchial outer diameter (Bout), bronchial lumen diameter (Bin), bronchial wall thickness (Bwt) and adjacent artery diameter (A); and computes Bout/A, Bin/A and Bwt/A for each BA pair from the segmental bronchi to the last visible generation. Three datasets were used to validate the automatic BA analysis. First BA analysis was executed on 23 manually annotated CT scans (11 CF, 12 control subjects) to compare automatic with manual BA-analysis outcomes. Furthermore, the BA analysis was executed on two longitudinal datasets (Copenhagen 111 CTs, ataluren 347 CTs) to assess longitudinal BA changes and compare them with manual scoring results.Results:The automatic and manual BA analysis showed no significant differences in quantifying bronchi. For the longitudinal datasets the automatic BA analysis detected 247 and 347 BA pairs/CT in the Copenhagen and ataluren dataset, respectively. A significant increase of 0.02 of Bout/A and Bin/A was detected for Copenhagen dataset over an interval of 2 years, and 0.03 of Bout/A and 0.02 of Bin/A for ataluren dataset over an interval of 48 weeks (all p&lt;0.001). The progression of 0.01 of Bwt/A was detected only in the ataluren dataset (p&lt;0.001). BA-analysis outcomes showed weak to strong correlations (correlation coefficient from 0.29 to 0.84) with manual scoring results for airway disease.Conclusion:The BA analysis can fully automatically analyse a large number of BA pairs on chest CTs to detect and monitor progression of bronchial wall thickening and bronchial widening in patients with CF

A new method to quantify and compare the multiple components of fitness-A study case with kelp niche partition by divergent microstage adaptations to Temperature

Point 1 Management of crops, commercialized or protected species, plagues or life-cycle evolution are subjects requiring comparisons among different demographic strategies. The simpler methods fail in relating changes in vital rates with changes in population viability whereas more complex methods lack accuracy by neglecting interactions among vital rates. Point 2 The difference between the fitness (evaluated by the population growth rate.) of two alternative demographies is decomposed into the contributions of the differences between the pair-wised vital rates and their interactions. This is achieved through a full Taylor expansion (i.e. remainder = 0) of the demographic model. The significance of each term is determined by permutation tests under the null hypothesis that all demographies come from the same pool. Point 3 An example is given with periodic demographic matrices of the microscopic haploid phase of two kelp cryptic species observed to partition their niche occupation along the Chilean coast. The method provided clear and synthetic results showing conditional differentiation of reproduction is an important driver for their differences in fitness along the latitudinal temperature gradient. But it also demonstrated that interactions among vital rates cannot be neglected as they compose a significant part of the differences between demographies. Point 4 This method allows researchers to access the effects of multiple effective changes in a life-cycle from only two experiments. Evolutionists can determine with confidence the effective causes for changes in fitness whereas population managers can determine best strategies from simpler experimental designs.CONICYT-FRENCH EMBASSADY Ph.D. gran

Methodological criteria for the assessment of moderators in systematic reviews of randomised controlled trials : a consensus study

Background: Current methodological guidelines provide advice about the assessment of sub-group analysis within RCTs, but do not specify explicit criteria for assessment. Our objective was to provide researchers with a set of criteria that will facilitate the grading of evidence for moderators, in systematic reviews. Method: We developed a set of criteria from methodological manuscripts (n = 18) using snowballing technique, and electronic database searches. Criteria were reviewed by an international Delphi panel (n = 21), comprising authors who have published methodological papers in this area, and researchers who have been active in the study of sub-group analysis in RCTs. We used the Research ANd Development/University of California Los Angeles appropriateness method to assess consensus on the quantitative data. Free responses were coded for consensus and disagreement. In a subsequent round additional criteria were extracted from the Cochrane Reviewers’ Handbook, and the process was repeated. Results: The recommendations are that meta-analysts report both confirmatory and exploratory findings for subgroups analysis. Confirmatory findings must only come from studies in which a specific theory/evidence based apriori statement is made. Exploratory findings may be used to inform future/subsequent trials. However, for inclusion in the meta-analysis of moderators, the following additional criteria should be applied to each study: Baseline factors should be measured prior to randomisation, measurement of baseline factors should be of adequate reliability and validity, and a specific test of the interaction between baseline factors and interventions must be presented. Conclusions: There is consensus from a group of 21 international experts that methodological criteria to assess moderators within systematic reviews of RCTs is both timely and necessary. The consensus from the experts resulted in five criteria divided into two groups when synthesising evidence: confirmatory findings to support hypotheses about moderators and exploratory findings to inform future research. These recommendations are discussed in reference to previous recommendations for evaluating and reporting moderator studies