Bilateral contact problem with adhesion and damage

We study a mathematical problem describing the frictionless adhesive contact between a viscoelastic material with damage and a foundation. The adhesion process is modeled by a bonding field on the contact surface. The contact is bilateral and the tangential shear due to the bonding field is included. We establish a variational formulation for the problem and prove the existence and uniqueness of the solution. The existence of a unique weak solution for the problem is established using arguments of nonlinear evolution equations with monotone operators, a classical existence and uniqueness result for parabolic inequalities, and Banach's fixed point theorem

Implementation, effectiveness and political context of comprehensive primary health care: preliminary findings of a global literature review

Primary health care (PHC) is again high on the international agenda. It was the theme of The World Health Report in 2008, thirty years after the Alma-Ata Declaration, and has been the topic of a series of significant conferences around the world throughout 2008. What have we learnt about its impact in improving population health and health equity? What more do we still need to know? These two questions framed a four-year international research/capacity-building project, “Revitalizing Health for All” (RHFA), funded by the Canadian Global Health Research Initiative, which began in 2007. The findings of a global literature review conducted by this Initiative, and focusing on comprehensive primary health care - and how it has been implemented since Alma Ata are presented. The way in which the political context has affected the comprehensiveness of PHC is considered - along with a series of proposed future PHC research areas.Web of Scienc

Evaluation of a Change Detection Methodology by Means of Binary Thresholding Algorithms and Informational Fusion Processes

Landcover is subject to continuous changes on a wide variety of temporal and spatial scales. Those changes produce significant effects in human and natural activities. Maintaining an updated spatial database with the occurred changes allows a better monitoring of the Earth’s resources and management of the environment. Change detection (CD) techniques using images from different sensors, such as satellite imagery, aerial photographs, etc., have proven to be suitable and secure data sources from which updated information can be extracted efficiently, so that changes can also be inventoried and monitored. In this paper, a multisource CD methodology for multiresolution datasets is applied. First, different change indices are processed, then different thresholding algorithms for change/no_change are applied to these indices in order to better estimate the statistical parameters of these categories, finally the indices are integrated into a change detection multisource fusion process, which allows generating a single CD result from several combination of indices. This methodology has been applied to datasets with different spectral and spatial resolution properties. Then, the obtained results are evaluated by means of a quality control analysis, as well as with complementary graphical representations. The suggested methodology has also been proved efficiently for identifying the change detection index with the higher contribution

Electromagnetic Characterization of a Composite (RE-CB-MT) by Time Domain Spectroscopy

The aim of this article is to study the dielectric behavior (ε, σ) in microwaves domain of composites made with Epoxy Resin (RE), Carbon Black (CB), and Magnesium Titanate (MT) on a large band of frequency. This kind of composites is very solicited for applications and miniaturization of the components circuits (cavities, antennas, substrates, etc.) in hyperfrequency electronics. In this study we have also highlighted the effect of the fillers nature and their concentrations on the behavior of these composites. The results obtained by time domain spectroscopy (TDS) have revealed the strong dependence of complex permittivity of the composite materials on both the nature and the concentration of conductive environment. Low frequency analysis (500 MHz) has been investigated to determine the conductivity of composites which is related to the percolation phenomenon. Moreover, the comparison between experimental results and theoretical models shows that the modeling Lichtenecker law is applicable to the ternary mixture in this frequency range and is in accordance with the approach postulated by Bottreau

Dielectric behavior of a sintered heterogeneous ternary composite resin/BT/Cu

In this paper, we investigate and model the dielectric behavior of a ternary composite prepared at room temperature with a mixture of epoxy resin (RE), barium titanate (BT) and copper oxide (Cu2O), sintered at three different temperatures (150 °C, 200 °C, and 250 °C). Time domain spectroscopy (TDS) is used to characterize samples in the range [DC to 2 GHz] by performing a particular study at low frequency (500 MHz). The latter focused on both the sintering and the Cu2O addition effects on a ternary composite dielectric behavior. These effects were quantified as a function of the BT volume fraction. For this purpose, we used an optimization method based on nonlinear regressions to determine the permittivity, to minimize systematic errors of this dielectric parameter, and to show the effect of Cu2O on it. Moreover, we attempt to explain the sintering temperature effect on this kind of mixtures through the modified Lichtenecker model. As a matter of fact, the importance of this law is allocated on one hand to the validation and concordance of the experimental results with those of the theory and on the other hand to the temperature effect investigation on the form factor given by the modified Lichtenecker law

Dielectric behavior of a quaternary composite (RE, BT, MnO

The main objective of this paper is to study the dielectric behavior of a quaternary composite, made from a mixture of barium titanate (BT), manganese dioxide (MnO2) and calcium oxide (CaO) in the same epoxy resin matrix (RE) maintained at 70% by volume fraction, while those of the other constituents are variable and completing each other in a way to achieve the remaining proportion, i.e. 30%. Random mixtures are made at room temperature and under atmospheric pressure. A dielectric characterization of this mixture type was performed by time-domain spectroscopy (TDS) over a frequency wide band (DC–2 GHz). This has been carried out to illustrate the effect of two oxides (MnO2 and CaO) simultaneously at low frequency (500 MHz), in the presence of (BT), on the composite dielectric behavior. This has led consequently to make a comparison between the present acquired results and those of the ternary composite, where (MnO2) and (CaO) act separately. The results obtained so far in this study allowed us to check the validity of the modified Lichtenecker law (MLL)-based predictive model in the quaternary composite case. The interest of this study lies on applications of these materials in microelectronics circuits and absorber materials in telecommunication domain

A frictional contact problem with damage and adhesion for an electro elastic-viscoplastic body

We consider a quasistatic frictional contact problem for an electro elastic-viscopalastic body with damage and adhestion. The contact is modelled with normal compliance. The adhesion of the contact surfaces is taken into account and modelled by a surface variable. We derive variational formulation for the model which is in the form of a system involving the displacement field, the electric potential field, the damage field and the adhesion field. We prove the existence of a unique weak solution to the problem. The proof is based on arguments of time-dependent variational inequalities, parabolic inequalities, differential equations and fixed point

Dielectric behavior of ternary mixtures: epoxy resin plus titanates (MgTiO

In the present work, we study the dielectric behavior of various ternary mixtures composed of epoxy resin (RE), of one of three different titanates (barium titanate, BaTiO3; calcium titanate, CaTiO3; magnesium titanate, MgTiO3) respectively with one of three oxides (calcium oxide, CaO; manganese dioxide, MnO2; zinc oxide, ZnO) using time domain reflectometry (TDR). The different composites are mixed at room temperature in different volume fractions keeping the epoxy resin at a constant volume fraction. Several mixture combinations are studied to see the oxides influence on the titanates dielectric behavior in the range from DC to 10 GHz. This is done through the experimental determination of the dielectric constant εs. A noticeable effect has been recorded at the low frequency and which consists of an increase of this dielectric permittivity when growing the volume fraction of manganese dioxide. One meaningful point of this study is the lowest static conductivity value (8.017 × 10−3/(Ωm)) being reached with an incursion of 7.5% of MnO2 in a ternary mixture composed of RE, MgTiO3 and MnO2. In addition, the behavior obtained experimentally has been validated by the Lichtenecker modified model. This study interest lies on an application of these materials in microelectronics and particularly in telecommunication components manufacturing

A description of female genital mutilation and force-feeding practices in Mauritania: implications for the protection of child rights and health.

OBJECTIVES: To establish the prevalence of female genital mutilation (FGM) and force feeding (gavage) practices among children in Mauritania; to investigate factors related to FGM and gavage practices and attitude in Mauritania; and to explore implications related to the protection of children's rights and welfare. METHODS: Data from the Mauritania 2000-2001 DHS were used in this analysis. Data were collected from men and women about their attitude toward the continuation of FGM and gavage; women only were asked if they ever experienced one of these practices. Chi-square statistics were used to investigate differences in attitude and practice of FGM and gavage by demographic characteristics. Binary logistic regression was used to identify socio-demographic factors related to FGM and gavage outcomes. FINDINGS: The overall prevalence of FGM was 77% but varied depending on ethnicity. The majority of both female and male respondents favored the continuation of the practice (64% and 70%, respectively). Almost a quarter (23%) of women reported being force fed as a child and 32% of women and 29% of men approved the continuation of the practice. Gavage is almost exclusively practiced among Arabs. CONCLUSION: The practice of both FGM and gavage is ongoing, although the prevalence and attitude towards both appears to vary as a function of ethnicity, wealth, education, marital status, and age. Contextually relevant intervention and enforcement strategies are needed to challenge these cultural norms and protect the rights and welfare of children in Mauritania

Le projet « Capdroits » ou comment la recherche en sciences sociales peut-elle participer à l’amélioration de l’exercice des droits de personnes en situation de handicap

International audienc