Influence of Concrete Moisture Condition on Half-Cell Potential Measurement

The detection of on-going corrosion is one of the main issues during inspection of reinforced concrete structures. The half-cell potential measurement method is the most common and established non-destructive technique to support this task. But a lot of infrastructures are exposed to rain or seawater, which can cause heterogeneous moisture condition within one component. In turn, this can have influence on the potential mapping results, and as a consequence, the interpretability of the half-cell potential measurement is impaired. This paper focuses on the influence of concrete moisture condition on half-cell potential measurement. Laboratory and practical tests’ results are analyzed qualitatively with varying moisture conditions due to natural exposure as well as with different prewetting conditions. On the basis of these results, recommendations are made how to evaluate half-cell potential mapping results. If large structures are inspected by half-cell potential measurements, it is advantageous to compare only these parts, which are in a comparable moisture condition by subdivision of the structure

Self-healing of concrete cracks by the release of embedded water repellent agents and corrosion inhibitors to reduce the risk for reinforcement corrosion

From the worldwide steel production, approximately 50 per cent is required to replace corroded steel [1]. In the case of reinforced concrete structures, corrosion of the reinforcement steel causes crack formation and spalling which leads to serviceability problems. Especially when small cracks are already present in the cementitious matrix in combination with aggressive ions present within the environment, a high risk for corrosion exists. Therefore, regular inspection, maintenance and crack repair are insurmountable for concrete structures. However, costs related to repair works mount up as not only the direct costs of the repair but also the indirect costs resulting from traffic jams and possible loss in productivity need to be taken into account. Self-repair of concrete cracks will have a high economic benefit as the indirect costs as well as a part of the direct costs can be avoided. In addition, it is assumed that self-repair will lead to more durable concrete structures as the risk for reinforcement corrosion may be decreased. The possibility to implement self-healing properties in concrete has been investigated for several years now. One of the studied self-healing approaches relies on the use of encapsulated healing agents which are embedded in the matrix. When cracks appear, the capsules break and the healing agent is released in the crack, causing crack repair. In previous research [2, 3] it was shown that by using this approach, part of the mechanical properties and the water tightness of cracks was restored. In this study we investigate whether by encapsulation and embedment of a water repellent agent (WRA) and/or a corrosion inhibitor (CI), we can reduce the risk for reinforcement corrosion. A selection of WRA and/or CI were encapsulated and embedded inside reinforced concrete beams which were cracked to trigger the self-healing mechanism. By electrochemical measurements it was shown that the risk for reinforcement corrosion was reduced in comparison to untreated cracks when the cracked beams, containing encapsulated WRA and/or CI, were exposed to a chloride solution

Comportements et représentations face à la dislocation des régulations sociales : L’hyperinflation en Argentine

Stabilité politique et stabilité économique Les coups d'État militaires et l'inflation ont été les deux sources de l'instabilité argentine. Depuis bientôt treize ans, l'Argentine connaît une stabilité politique qui lui a longtemps fait défaut ; rares avaient été les gouvernements assurés de finir leur mandat ; de même, ne faut-il pas oublier qu'il n'y avait pas eu d'alternance politique constitutionnelle de 1928 à 1989. A la différence des pays de l'Est, la démocratisation argentine a consis..

Test methods to determine durability of concrete under combined environmental actions and mechanical load: final report of RILEM TC 246-TDC

At present several methods are available to predict the durability of reinforced concrete structures. In most cases, one dominant deterioration process such as carbonation or chloride penetration is taken into consideration. Experimental results as well as observations in practice show that this is not a realistic and certainly not a conservative approach. In order to test more realistically, RILEM TC 246-TDC, founded in 2011, has developed a method to determine the durability of concrete exposed to the combined action of chloride penetration and mechanical load. In this report, a test method is presented which allows determination of realistic diffusion coefficients for chloride ions in concrete under compressive or tensile stress. Comparative test results from five different laboratories showed that the combination of mechanical and environmental loads may be much more severe than a single environmental load without mechanical loading. Modelling and probabilistic analysis also showed that the obvious synergetic effects cannot be neglected in realistic service life prediction

Doctor competence and the demand for healthcare : evidence from rural China

The agency problem between patients and doctors has long been emphasised in the health economics literature, but the empirical evidence on whether patients can evaluate and respond to better quality care remains mixed and inconclusive. Using household data linked to an assessment of village doctors' clinical competence in rural China, we show that there is no correlation between doctor competence and patients' healthcare utilisation, with confidence intervals reasonably tight around zero. Household perceptions of quality are an important determinant of care seeking behaviour yet patients appear unable to recognise more competent doctors -there is no relationship between doctor competence and perceptions of quality

Distinct nonequilibrium plasma chemistry of C2 affecting the synthesis of nanodiamond thin films from C2H2 (1%)/H2/Ar-rich plasmas

6 pages, 5 figures, 6 tables.We show that the concentrations of the species C2 (X 1Σg+), C2 (a 3Πu), and C2H exhibit a significant increase when the argon content grows up to 95% in medium pressure (0.75 Torr) radio frequency (rf) (13.56 MHz) produced C2H2 (1%)/H2/Ar plasmas of interest for the synthesis of nanodiamond thin films within plasma enhanced chemical vapor deposition devices. In contrast, the concentrations of CH3 and C2H2 remain practically constant. The latter results have been obtained with an improved quasianalytic space–time-averaged kinetic model that, in addition, has allowed us to identify and quantify the relative importance of the different underlying mechanisms driving the nonequilibrium plasma chemistry of C2. The results presented here are in agreement with recent experimental results from rf CH4/H2/Ar-rich plasmas and suggest that the growth of nanodiamond thin films from hydrocarbon/Ar-rich plasmas is very sensitive to the contribution of C2 and C2H species from the plasma.This work was partially funded by CICYT (Spain) under a Ramón y Cajal project and under Project No. TIC2002- 03235. One of the authors (F.J.G.V.) acknowledges a Ramón y Cajal contract from the Spanish Ministry of Science and Technology (MCYT). One of the authors (J.M.A.) acknowledges partial support from CICYT (Spain) under Project No. MAT 2002-04085-C02-02.Peer reviewe

A life-course and time perspective on the construct validity of psychological distress in women and men. Measurement invariance of the K6 across gender

<p>Abstract</p> <p>Background</p> <p>Psychological distress is a widespread indicator of mental health and mental illness in research and clinical settings. A recurrent finding from epidemiological studies and population surveys is that women report a higher mean level and a higher prevalence of psychological distress than men. These differences may reflect, to some extent, cultural norms associated with the expression of distress in women and men. Assuming that these norms differ across age groups and that they evolve over time, one would expect gender differences in psychological distress to vary over the life-course and over time. The objective of this study was to investigate the construct validity of a psychological distress scale, the K6, across gender in different age groups and over a twelve-year period.</p> <p>Methods</p> <p>This study is based on data from the Canadian National Population Health Survey (C-NPHS). Psychological distress was assessed with the K6, a scale developed by Kessler and his colleagues. Data were examined through multi-group confirmatory factor analyses. Increasing levels of measurement and structural invariance across gender were assessed cross-sectionally with data from cycle 1 (n = 13019) of the C-NPHS and longitudinally with cycles 1 (1994-1995), 4 (2000-2001) and 7 (2006-2007).</p> <p>Results</p> <p>Higher levels of measurement and structural invariance across gender were reached only after the constraint of equivalence was relaxed for various parameters of a few items of the K6. Some items had a different pattern of gender non invariance across age groups and over the course of the study. Gender differences in the expression of psychological distress may vary over the lifespan and over a 12-year period without markedly affecting the construct validity of the K6.</p> <p>Conclusions</p> <p>This study confirms the cross-gender construct validity of psychological distress as assessed with the K6 despite differences in the expression of some symptoms in women and in men over the life-course and over time. Findings suggest that the higher mean level of psychological distress observed in women reflects a true difference in distress and is unlikely to be gender-biased. Gender differences in psychological distress are an important public health and clinical issue and further researches are needed to decipher the factors underlying these differences.</p

Global patterns and drivers of alpine plant species richness

Aim Alpine ecosystems differ in area, macroenvironment and biogeographical history across the Earth, but the relationship between these factors and plant species richness is still unexplored. Here, we assess the global patterns of plant species richness in alpine ecosystems and their association with environmental, geographical and historical factors at regional and community scales. Location Global. Time period Data collected between 1923 and 2019. Major taxa studied Vascular plants. Methods We used a dataset representative of global alpine vegetation, consisting of 8,928 plots sampled within 26 ecoregions and six biogeographical realms, to estimate regional richness using sample‐based rarefaction and extrapolation. Then, we evaluated latitudinal patterns of regional and community richness with generalized additive models. Using environmental, geographical and historical predictors from global raster layers, we modelled regional and community richness in a mixed‐effect modelling framework. Results The latitudinal pattern of regional richness peaked around the equator and at mid‐latitudes, in response to current and past alpine area, isolation and the variation in soil pH among regions. At the community level, species richness peaked at mid‐latitudes of the Northern Hemisphere, despite a considerable within‐region variation. Community richness was related to macroclimate and historical predictors, with strong effects of other spatially structured factors. Main conclusions In contrast to the well‐known latitudinal diversity gradient, the alpine plant species richness of some temperate regions in Eurasia was comparable to that of hyperdiverse tropical ecosystems, such as the páramo. The species richness of these putative hotspot regions is explained mainly by the extent of alpine area and their glacial history, whereas community richness depends on local environmental factors. Our results highlight hotspots of species richness at mid‐latitudes, indicating that the diversity of alpine plants is linked to regional idiosyncrasies and to the historical prevalence of alpine ecosystems, rather than current macroclimatic gradients

Roles and practices of general practitioners and psychiatrists in management of depression in the community

BACKGROUND: Little is known about depressed patients' profiles and how they are managed. The aim of the study is to compare GPs and psychiatrists for 1°) sociodemographic and clinical profile of their patients considered as depressed 2°) patterns of care provision. METHODS: The study design is an observational cross-sectional study on a random sample of GPs and psychiatrists working in France. Consecutive inclusion of patients seen in consultation considered as depressed by the physician. GPs enrolled 6,104 and psychiatrists 1,433 patients. Data collected: sociodemographics, psychiatric profile, environmental risk factors of depression and treatment. All clinical data were collected by participating physicians; there was no direct independent clinical assessment of patients to check the diagnosis of depressive disorder. RESULTS: Compared to patients identified as depressed by GPs, those identified by psychiatrists were younger, more often urban (10.5% v 5.4% – OR = 2.4), educated (42.4% v 25.4% – OR = 3.9), met DSM-IV criteria for depression (94.6% v 85.6% – OR = 2.9), had been hospitalized for depression (26.1% v 15.6% – OR = 2.0) and were younger at onset of depressive problems (all adjusted p < .001). No difference was found for psychiatric and somatic comorbidity, suicide attempt and severity of current depression. Compared to GPs, psychiatrists more often prescribed tricyclics and very novel antidepressants (7.8% v 2.3% OR = 5.0 and 6.8% v 3.0% OR = 3.8) with longer duration of antidepressant treatment. GPs' patients received more "non-conventional" treatment (8.8% v 2.4% OR = 0.3) and less psychotherapy (72.2% v 89.1% OR = 3.1) (all adjusted p < .001). CONCLUSION: Differences between patients mainly concerned educational level and area of residence with few differences regarding clinical profile. Differences between practices of GPs and psychiatrists appear to reflect more the organization of the French care system than the competence of providers