Enrico di Bella

Influence of water sorption on resin composite color and color variation amongst various composite brands with identical shade code: an in vitro evaluation

OBJECTIVE The aim of this study was to evaluate the influence of 1 week water storage on color stability of A2 enamel and dentine shade of 13 resin composites intended for anterior restorations and to evaluate the interchangeability of different composite brands of equal color shade. METHODS 6 samples per shade were prepared as 1mm thick discs of 10mm diameter. L*a*b* and contrast ratio (CR) were measured immediately after light curing and after 1 week storage in water at 37°C, in the dark. Then all samples were compared against each other. RESULTS The greatest color change was found for Enamel A2 Artemis (ΔE 3.13) with white background whilst the smallest was Dentine A2 Filtek and Voco (ΔE 0.20) with black background. SIGNIFICANCE Most of resin composite brands showed statistically significant differences between initial and post immersion color values. Some of post ageing dentine and enamel CR values was statistically different amongst them. The color differences in-between all the A2 enamel and dentine composite shades were highly statistically different.

A multivariate classification of open source developers

Open source software development is becoming always more relevant. Understanding the behavior of developers in open source software projects and identifying the kinds of their contributions is an essential step to improve the efficiency of the development process and to organize the development teams more effectively. Moreover, understanding the level of participation of the different developers helps to understand which members of the development team are more important than others and who are the actual key developers. This paper investigates the behavior of open source developers and the structure of the development of open source projects through the analysis of a very large dataset: 10 well-known and widely used open source software projects for a total of more than 4 MLOC (millions of lines of code) modified distributed in more than 200K versions. This study builds on the top of other studies in this area applying a set of rigorous statistical techniques, analyzing how developers contribute to the projects. Its novelty is in the fine gain analysis of the developers that have commit rights on the repository of the project they work on, in the automated identification of key contributors of the project, in the size of the analyzed datasets, and in the statistical techniques used to classify the behavior of the developers in an automated way. To collect such large volume of data and to ensure their integrity, a tool to automatically mine open source version control systems has been used. The main result of this study is the identification of a recurrent pattern of four kinds of contributors with the same characteristics in all the projects analyzed even if the projects are very different in domain, size, language, etc.

EEG Evidence of Posterior Cortical Disconnection in PD and Related Dementias

ABSTRACT Electroencephalogram (EEG) reactivity to eyes opening and 12-Hz photic stimulation was investigated in 14 healthy elderly subjects, 21 parkinsonian patients (PD), 7 demented parkinsonian patients (PDD), and 10 patients with Lewy body dementia (LBD) using global field synchronization (GFS). During eyes closed Theta GFS was increased in Parkinsons disease and patients and alpha1 GFS was decreased in LBD subjects. During 12-Hz intermittent photic stimulation (IPS), reactivity of posterior electrodes was decreased in PD and LBD patients. No reactivity was observed in PDD. Results are consistent with a graded posterior cortical disconnection in parkinsonian syndromes and with a model of dopamine-modulated thalamocortical interplay in visual processing.

Colour stainability of indirect CAD–CAM processed composites vs. conventionally laboratory processed composites after immersion in staining solutions

OBJECTIVES The aim of this study was to determine, by using a spectrophotometer device, the colour stainability of two indirect CAD/CAM processed composites in comparison with two conventionally laboratory-processed composites after being immersed 4 weeks in staining solutions such as coffee, black tea and red wine, using distilled water as control group. METHODS Two indirect CAD/CAM composites (Lava Ultimate and Paradigm MZ100) and two conventionally laboratory-processed composites (SR Adoro and Premise Indirect) of shade A2 were selected (160 disc samples). Colour stainability was measured after 4 weeks of immersion in three staining solutions (black tea, coffee, red wine) and distilled water. Specimens colour was measured each week by means of a spectrophotometer (CIE L*a*b* system). Statistical analysis was carried out performing repeated ANOVA measurements and Tukeys HSD test to evaluate differences in ΔE00 measurements between groups; the interactions among composites, staining solutions and time duration were also evaluated. RESULTS All materials showed significant discoloration (p<0.01) when compared to control group. The highest ΔE00 observed was with red wine, whereas black tea showed the lowest one. Indirect laboratory-processed resin composites showed the highest colour stability compared with CAD/CAM resin blocks. CONCLUSIONS CAD/CAM processed composites immersed in staining solutions showed lower colour stability when compared to conventionally laboratory-processed resin composites. CLINICAL SIGNIFICANCE The demand for CAD/CAM restorations has been increasing; however, colour stainability for such material has been insufficiently studied. Moreover, this has not been performed comparing CAD/CAM processed composites versus laboratory-processed indirect composites by immersing in staining solutions for long immersion periods.

Influence of filler charge on gloss of composite materials before and after in vitro toothbrushing

OBJECTIVES This study evaluated the gloss behaviour of experimental resin composites loaded with different filler percentages, immediately after polishing and after toothbrushing simulation. METHODS Sixteen disc-shaped specimens were fabricated for each different-charged composite (40%, 50%, 60%, 70% and 75%) and polished with SiC abrasive papers. Gloss measurements were made prior to simulated toothbrushing. The specimens were subjected to the simulation for 5, 15, 30 and 60 min using an electrical toothbrush with a standardized pressure while being immersed in a toothpaste/artificial saliva slurry. RESULTS Baseline composite gloss values ranged from 69.7 (40%) to 81.3 (75%) GU (gloss units) and from 18.1 (40%) to 32.3 (75%) GU after 1h of brushing. Highest gloss values were obtained by 75%-charged resin, while the lowest values were obtained by the 40%-charged one. CONCLUSIONS All tested materials showed a gloss decrease. However, the higher filler load a composite resin has, the higher gloss it can achieve. CLINICAL SIGNIFICANCE Gloss of resin composite materials is an important factor in determining aesthetic success of anterior restorations, and this property may vary according to the filler charge of the restorative material. Higher filler load of a composite resin results in higher gloss values.

Spatial Autoregressive Models for House Price Dynamics in Italy

This paper elaborates a Spatial Autoregressive and Spatial Error Model (SAR-SE Model) to investigate the Italian house price dynamics. House prices in real terms have been modelled for the period 1995-2008 in all the 103 Italian provinces along with affordability ratio, persistency term, some social-economic variables and credit market variables. One of the key results of this paper, is the evidence on house price spatial autocorrelation, verified through the Baltagi, Song and Koh (2003) LM test. On the contrary, no evidence of housing price overvaluation has been found, in comparison with the fundamental values determined by interest rates, households income, rents, employment and construction cost.

The spatial configuration of urban crime environments and statistical modeling

The aim of this paper is to discuss the representation of space in statistical models of urban crime. We argue that some important information represented by the properties of space is either lost or hardly interpretable if those properties are not explicitly introduced in the model as regressors. We illustrate the issue commenting on the shortcomings of the two standard approaches to modeling the dispersion of crime in a city: using local attributes of places as regressors, and defining a catch-all spatial component to neutralize the effect of latent spatial factors from the model. As an alternative to the current methods, the metrics of spatial configuration, including those devised by the technique called Space Syntax Analysis, provide useful variables that can be introduced as regressors. Such regressors offer interpretable information on space, behavior, and their interactions, that would otherwise be lost. We therefore consider a set of three configurational variables that represent different forms of centrality and that are thought to have influence on a wide range of human activities. We propose an innovative procedure to adapt these variables to most urban graphs and then, using data from a large area in the city of Genoa (Italy), we show that the three variables are well defined, consistent, noncollinear indicators, with evident spatial meanings. Then we build two sets of Hierarchical Bayesian count models of different urban crime types (“property crime” and “arson and criminal damage”) around some known covariates of crime and we show that the overall quality of the models is improved (with the size of improvement depending on the type of crime) when the three configurational variables are included. Furthermore, we show that what the three variables explain of the overall variability of crime is a sizeable part of what would be the spatial error term of a traditional spatial model of urban crime. While the configurational variables alone cannot provide a goodness of fit as high as the one obtained with a generic spatial term, they have a relevant role for the interpretation of the results, which is ultimately the objective of urban crime modeling.

POSET Analysis of Panel Data with POSAC

In the last two decades, data-driven policymaking has gained more and more importance due to the larger availability of data (and, more recently, Big Data) for designing proper and timely economic and social policies. This larger availability of data has let decision makers have a deeper insight of complex socio-economic phenomena (e.g. unemployment, deprivation, crime, social care, healthcare) but, at the same time, it has drastically increased the number of indicators that can be used to monitor these phenomena. Decision makers are now often in the condition of taking decisions with large batteries of indicators whose interpretation is not always easy or concordant. In order to simplify the decisional process, a large body of literature suggests to use synthetic indicators to produce single measures of vast, latent phenomena underlying groups of indicators. Unfortunately, although simple, this solution has a number of drawbacks (e.g. compensation between components of synthetic indicators could be undesirable; subjective weighting of the components could lead to arbitrary results; mixing information about different phenomena could make interpretation harder and decision-making opaque). Moreover, with operational decisions, it is necessary to distinguish between those situations when decisions can be embedded in automated processes, and those that require human intervention. Under certain conditions, the use of synthetic indicators may bring to a misleading interpretation of the real world and to wrong policy decisions. In order to overcome all these limitations and drawbacks of synthetic indicators, the use of multi-indicator systems is becoming more and more important to describe and characterize many phenomena in every field of science, as they keep the valuable information, inherent to each indicator, distinct (see, for a review: Bruggemann and Patil 2011).

Popular initiatives in 2014–2016 call for the introduction of mandatory dental care insurance in Switzerland: The contrasting positions at stake ☆

Switzerlands mandatory health insurance system provides coverage for a standard benefits package for all residents. However, adult dental care is covered only in case of accidents and inevitable dental illnesses, while routine dental care is almost completely financed out-of-pocket. In general, unmet health needs in Switzerland are low, but unmet dental needs are significant, when compared with other countries in Europe. Recent popular initiatives in Switzerland have aimed to introduce a mandatory insurance model for dental care through a mandatory contribution of 1% of gross salaries toward dental care insurance. In three cantons, the proposals have collected the required number of signatures and a public referendum is expected to be held in 2017/2018. If implemented, the insurance system is expected to have a significant impact on the dental profession, dental care demand, and the provision of dental services. The contrasting positions of stakeholders for and against the reform reflect a rare situation in which dental care policy issues are being widely discussed at all levels. However, such a discussion is of crucial relevance not only for Switzerland, but also for the whole of Europe, which has significant levels of unmet needs for dental care, especially among vulnerable and deprived individuals, and new solutions to expand dental care coverage are required.

Robustness and Effectiveness of the Triage System in the Pediatric Context

BackgroundThe increasing use of emergency departments (EDs) potentially compromises their effectiveness and quality. The evaluation of the performance of the triage code system in a pediatric context is important because waiting time affects the quality of care for acutely ill patients.ObjectiveIn this study, we aimed to assess the effectiveness and robustness of the triage code system in a pediatric context and identify the determinants of waiting times for urgent and non-urgent patients.MethodsData regarding 37,767 pediatric patients who accessed the ED of a major Italian pediatric hospital in 2015 were investigated in order to study patient numbers and waiting times. The determinants of waiting times for urgent and non-urgent patients, as well as variables referring to the “supply side,” such as periods of staff shortage, were analyzed using a survival analysis framework.ResultsFor urgent patients, the waiting time between triage and the first physician assessment is generally below the standard threshold of 15 min and this is not affected by the number of non-urgent patients waiting for care. Conversely, the waiting time for non-urgent patients is affected by ED flow, periods of staff shortage, and non-clinical variables (age and nationality).ConclusionOur results suggest that the triage level assignation system is effective in terms of safety for urgent patients. The current ED organization adequately fulfills its primary goal of providing healthcare for acutely ill patients.