Study on the potential inhibition of root dentine wear adjacent to fluoride-containing restorations

The purpose of this in vitro study was to determine whether the vicinity of root dentine that had been restored with fluoride-releasing materials was at reduced risk for erosive/abrasive wear compared to root dentine restored with a non-fluoride-containing material. According to a randomized complete block design, standardized cavities prepared on the surface of 150 bovine root dentine slabs were restored with glass-ionomer cement, resin-modified glass ionomer, polyacid-modified resin composite, fluoride-containing or conventional composite. Specimens were coated with two layers of an acid-resistant nail varnish exposing half of the dentine surface and half of the restoration. Subsequently, specimens were either eroded in an acidic drink or left uneroded, then exposed to artificial saliva and abraded in a toothbrushing machine. Wear depth in the vicinity of restorations was quantified by a stylus profilometer, based on the nonabraded areas surrounding the erosion/abrasion region. Two-way ANOVA did not demonstrate significant interaction between restoratives and eroded-uneroded dentine (p = 0.5549) nor significant difference among restorative materials (p = 0.8639). Tukey’s test ascertained that the wear depth was higher for eroded than for uneroded groups. Fluoride-releasing materials seemed to negligibly inhibit wear in the vicinity of restored root dentine subjected to erosive/abrasive challenges.     

Taking the easy way out: Preference diversity, decision strategies, and decision refusal in groups.

It has often been argued and found that preference diversity is beneficial for the quality of group decisions. However, this literature has neglected the fact that in many situations, it is also possible not to choose. Further, preference diversity can be based on attractions, aversions, or both. The authors argue that some types of preference diversity can lead to biased discussions and choice refusal (i.e., the group refuses to choose any of the available options). In a laboratory experiment, three different patterns were observed. When group members held different aversions before discussion, discussions were aversion driven and group members quickly agreed to refuse all alternatives. When each alternative had both a proponent and an adversary, discussions were longer and unbiased but still often led to refusal, which was accompanied by relatively low levels of outcome satisfaction. Only when preference diversity was based only on attractions did it lead to unbiased discussion, low prevalence of refusal, and high outcome satisfaction. Implications for group decision making are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Criticality of the measurement of corneal thickness in specular reflection by digital biomicroscope

Purpose

The aim was to evaluate the effects on corneal thickness (t) measurement, of asymmetry of the CCD position for a digital biomicroscope in specular reflection.

Incorporating a Systemic and Foresight Approach into Smart City Initiatives: The Case of Spanish Cities

At the dawn of the twenty-first century, cities face serious societal, economic, environmental, and governance challenges. Under the term “Smart City,” numerous technology-based initiatives are emerging to help cities face contemporary challenges while the concept itself is evolving towards a more holistic approach. Nevertheless, the capability of smart initiatives to provide an integrated vision of our cities is still very limited. Eventually, many of these initiatives do not fulfill satisfactorily their initial objectives because they fail to understand the complexity, diversity, and uncertainty that characterize contemporary cities. The purpose of this paper is twofold: to display an urban functional system, capable of interpreting the city in a more holistic way, and to incorporate foresight tools so as to formulate Smart City visions in a more participatory way with the involvement of local stakeholders.     

H2S photodegradation by TiO2/M-MCM-41 (M = Cr or Ce): Deactivation and by-product generation under UV-A and visible light

M-MCM-41 molecular sieves (M = Ce or Cr) were prepared by a hydrothermal method and impregnated with TiO₂. The materials were characterized by XRD, N₂ adsorption–desorption, DRS and XPS. Their potential application to photooxidize H₂S in a wet gas stream was tested in a continuous flow reactor operating at a flow rate of 110 mL min⁻¹ at 50% relative humidity and using 30 ppm_v of the pollutant. The photocatalytic efficiency using UV-A and visible light was compared to the activity of TiO₂/MCM-41 without heteroatoms incorporated into the MCM-41 structure. It was found that the incorporation of Ce did not improve the performance of TiO₂/MCM-41, but Cr-containing samples presented higher initial efficiency and were able to photooxidize H₂S without formation of SO₂ as a by-product, in contrast to the other prepared samples and to Degussa P-25 TiO₂. Moreover, no other gaseous by-product was detected. The isomorphic incorporation of Cr into the structure of MCM-41 followed by TiO₂ incorporation produced photocatalysts that presented good adsorption capacity and were much more active under visible light than under UV-light. This performance represents an important advantage for solar applications. Their photoactivity depended on the concentration of chromium; the highest efficiency was attained with samples with a Si/Cr ratio of 50. Finally, deactivation was observed as a consequence of sulfate accumulation on the surface of the catalyst and reduction of Cr⁶⁺.     

Reflection photoelastic tomography for the detection of stress distribution in planar optical waveguides

A novel method for measuring local stress distributions and birefringence of films on substrates and planar optical waveguides, with submicrometric resolution, is presented. The technique relies on a reflective tomographic configuration, applied in conjunction with a polarimetric setup, which processes the stress-induced change of the state of polarization of a laser probe beam reflected at the waveguide-substrate (film-substrate) interface. By this means, theoretically foreseen stress behavior can be experimentally verified and spurious or induced local stress variations in integrated optics components can also be brought into evidence. The feasibility of the proposed method has been verified by reconstructing the two-dimensional axial stress distribution in the 4 x 2 microm(2) core region of a doped silica-on-silicon optical waveguide.     

Digital in-line soft x-ray holography with element contrast

Digital in-line soft x-ray holography (DIXH) was used to image immobilized polystyrene and iron oxide particles and to distinguish them based on their different x-ray absorption cross sections in the vicinity of the carbon K-absorption edge. The element-specific information from the resonant DIXH images was correlated with high-resolution scanning electron microscopy (SEM) pictures. We also present DIXH images of a cell nucleus and compare the contrast obtained for nuclear components with the appearance in optical microscopy.     

Oxygen and water vapor barrier properties of MMT nanocomposites from low density polyethylene or EPM with grafted succinic groups

LDPE, EPM and their derivatives containing a moderate amount (0.08-1.8 by mol) of diethylsuccinate or succinic anhydryde groups were used as matrices in blending with different amount of organophilic montmorillonites and the resulting composite morphology and structure (by XRD, SEM, TEM microscopy, DSC analysis and selective solvent extraction) were studied with reference to the polar groups/MMT ratio. Exfoliated, intercalated and mixed morphologies were achieved. High concentrations of polar groups grafted to the polyolefin and montmorillonite loading not larger than 5% wt were favourable for obtaining high exfoliation degree. Particularly in the exfoliated MMT composite LDPE had lower crystallinity degree, while EPM showed increased glass transition temperature and reduced solubility in hot toluene. Moreover, oxygen and water vapor barrier property improvement was observed in films where MMT exhibits either exfoliated or intercalated morphologies. Strong interactions with the montmorillonite particle surface through the polar groups grafted to the polyolefin seems to be the basic effect responsible for the morphology and peculiar properties. A model based on the reduced mobility of the polymer located near the particle surface or inside the MMT gallery (confined phase) was proposed to explain the observed oxygen permeability reduction, the T(g) increase and solubility of poly(ethylene-ran-propylene)/MMT nanocomposites.     

PULP: A Ultra-Low Power Parallel Accelerator for Energy-Efficient and Flexible Embedded Vision

Novel pervasive devices such as smart surveillance cameras and autonomous micro-UAVs could greatly benefit from the availability of a computing device supporting embedded computer vision at a very low power budget. To this end, we propose PULP (Parallel processing Ultra-Low Power platform), an architecture built on clusters of tightly-coupled OpenRISC ISA cores, with advanced techniques for fast performance and energy scalability that exploit the capabilities of the STMicroelectronics UTBB FD-SOI 28nm technology. We show that PULP performance can be scaled over a 1x-354x range, with a peak theoretical energy efficiency of 211 GOPS/W. We present performance results for several demanding kernels from the image processing and vision domain, with post-layout power modeling: a motion detection application that can run at an efficiency up to 192 GOPS/W (90 % of the theoretical peak); a ConvNet-based detector for smart surveillance that can be switched between 0.7 and 27fps operating modes, scaling energy consumption per frame between 1.2 and 12mJ on a 320 ×240 image; and FAST + Lucas-Kanade optical flow on a 128 ×128 image at the ultra-low energy budget of 14 μJ per frame at 60fps.