Influence of chemical and mineralogical composition of concrete aggregates on their behaviour at elevated temperature

The nature of aggregates has an important influence on the behaviour of concrete at high temperature. The aggregates used in concrete are classified into two categories: siliceous (S) and calcareous (C). Most publications and Eurocode 2 Part 1–2 underline concrete containing C aggregates have a better thermal resistance in comparison to concrete with S aggregate. Recent studies show that rocks of identical chemical nature can have different behaviour during a temperature rise. Therefore, the improvement for understanding the thermal damage process of aggregates is necessary. An experimental study performed on three different aggregates (limestone, flint and quartzite) underwent heating–cooling cycles at 150, 300, 450, 600 and 750 °C is discussed in this paper. For a same S nature, the flint showed a spalling phenomenon from 300 to 500 °C, while quartzite had a good thermal stability up to 750 °C. C aggregates presented instability due to decarbonation/hydration after the heating/cooling cycle at 750 °C. The physico-chemical, mineralogical and microstructural evolutions of these aggregates with temperature were analysed to better understand the instability process of concrete aggregates. The evolution of flint damage is especially described by a series of observations of cracking from macroscopic to nanoscopic scale through microscopic scale. Aggregates have a high temperature behaviour very different depending on their physicochemical properties. Distinguishing aggregates according to their mineralogical nature only may not completely be sufficient to anticipate their thermal stability. The distinction between S versus C prescribed by the Eurocode 2 Part 1–2 for calculating concrete compressive strength at elevated temperature is not sufficiently precise or relevant.     

Multisystemic Treatment: A Meta-Analysis of Outcome Studies.

Multisystemic treatment (MST) is a family- and home-based therapeutic approach that has been found to be effective in treating antisocial youths and that has recently been applied to youths with serious emotional disturbances. In light of the increasing dissemination of MST, this review examines the effectiveness of MST by quantifying and summarizing the magnitude of effects (treatment outcomes) across all eligible MST outcome studies. Included in a meta-analysis were 7 primary outcome studies and 4 secondary studies involving a total of 708 participants. Results indicated that across different presenting problems and samples, the average effect of MST was d = .55; following treatment, youths and their families treated with MST were functioning better than 70% of youths and families treated alternatively. Results also showed that the average effect of MST was larger in studies involving graduate student therapists (i.e., efficacy studies; d = .81) than in studies with therapists from the community (i.e., effectiveness studies; d = .26). In addition, MST demonstrated larger effects on measures of family relations than on measures of individual adjustment or peer relations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Concluding causation from correlation: Comment on Burns and Spangler (2000).

This commentary critiques the study conducted by D. D. Burns and D. Spangler (2000) (see record 2000-13544-005) in which the relationship between homework compliance and therapy outcome was estimated using structural equation modeling (SEM). Although the authors, of the commentary advocate the use of SEM, they suggest greater caution in the indiscriminate endorsement of a causal relationship based on (a) correlational data and (b) retrospective accounts of the main predictor variable within a cross-sectional design. This discussion also highlights a need to address the issue of therapist competence in homework administration. The results of Burns and Spangler's report are consistent with existing empirical evidence suggesting that compliance with homework facilitates therapeutic outcome. However, the gold standard for determining causal inferences rests on prospective, experimental research rather than on retrospective, correlational models. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dangerous misidentification of people due to flashback phenomena in posttraumatic stress disorder

Changes in the fatty acid composition of phospholipid and triglyceride fractions in Spirometra erinaceieuropaei plerocercoids were investigated after 0, 0.5, 1, 3, and 6 hr incubation at 10 C and 37 C with physiological saline containing 5 mM arachidonic acid and 10 mg/ml bovine serum albumin, pH 7.0. At 37 C, arachidonic acid was absorbed and incorporated rapidly into the triglyceride fraction (over 14.4% in composition), and decreased after 2-3 hr; at 10 C, the amount of triglyceride increased slowly and continued to a maximum of 12.9% during 6 hr of incubation. We used a simplified method to extract and purify prostaglandins from the plerocercoid of S. erinaceieuropaei. Prostaglandins were quantified using gas chromatography-mass spectrometry. Prostaglandin E2, PGD2, PGF2alpha, and 6-keto-PGF1alpha were detected under different incubation conditions. In the dose-dependent experiment, PGD2 was detected in plerocercoids incubated with 0.5, 1, 2, and 5 mM arachidonic acid, pH 7.0, at 25 C; PGE2 was detected with 2 and 5 mM arachidonic acid. In the time-dependent experiment, where plerocercoids were incubated with 5 mM arachidonic acid, pH 7.0 at 25 C, PGF2alpha was first detected at 15 min; thereafter, 6-keto-PGF1alpha was detected at 30 min and PGD2 and PGE2 were detected at 1 hr. Thromboxane B2 was not detected in either the dose-dependent or time-dependent experiments, and only PGE2 was detected in the incubation medium with 5 mM arachidonic acid at 1 hr. These results reveal that when plerocercoids change from reptilian to mammalian hosts, they are able to absorb and modify arachidonic acid bound to albumin and generate prostaglandins under suitable conditions. Prostaglandins exhibit potent biological functions for immunoresponses that may be relevant to parasitism and the success of larva migrans in S. erinaceieuropaei.     

Doses under automatic exposure control (AEC) for direct digital radiographic (DDR) X-ray systems

Current guidelines quote tolerances for automatic exposure control (AEC) device performance for X-ray systems as 'Baseline ± X %'. However, in the situation where a baseline figure has not yet been achieved, as in the case of commissioning assessments, this tolerance is not relevant. The purpose of this work is to provide mean doses for direct digital radiography (DDR) X-ray system, operating in AEC, against which comparisons can be made. Dose measurements have been recorded under AEC operation on 29 DDR detectors from three different manufacturers. Two different testing protocols were examined: (1) water equivalent phantoms in front of the DDR detector and (2) aluminium block at the tube head. The average patient exit dose, using the aluminium block was 4.6 μGy with the antiscatter grid in place and 4.0 μGy with the grid removed. Using the water phantoms, the average dose was measured at 17.1 μGy with the antiscatter grid in place and 5.4 μGy with grid removed. Based on these results, it is clear that different testing configurations significantly impact on the measured dose.     

Effects of labor contractions on catecholamine release and breathing frequency in newborn rats.

Plasma catecholamines in newborn rats (0-2 hr old) were analyzed following vaginal birth, cesarean section with simulated labor contractions, or cesarean section without labor contractions. Upon delivery, pups were exposed to key elements of the rat's natural birth process, that is, umbilical cord occlusion, tactile stimulation, and cooling. Only pups exposed to actual or simulated labor showed an immediate rise in norepinephrine and epinephrine. Initial postpartum respiratory frequencies were higher in vaginal than in cesarean delivered pups and, in all groups, inversely correlated with catecholamine titers, suggesting respiratory distress or transient tachypnea at lower catecholamine levels. These findings establish a rat model for analyzing effects of labor on neonatal adaptive response during the transition from prenatal to postnatal life. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissemination and effectiveness of multisystemic treatment in New Zealand: A benchmarking study.

The transportability of Multisystemic Therapy (MST) for the treatment of juvenile offenders in a community-based context was examined in the current study. Results of this New Zealand study showed that significant pre- to posttreatment improvements occurred on most indicators of ultimate (i.e., offending behavior) and instrumental (i.e., youth compliance, family relations) treatment outcomes. Reductions in offending frequency and severity continued to improve across the 6- and 12-month follow-up intervals. In comparison to benchmarked studies, the current study demonstrated a more successful treatment completion rate. Additionally, overall treatment effect sizes were found to be clinically equivalent with the results of previous MST outcome studies with juvenile offenders and significantly greater than the effect sizes found in the control conditions. The findings of this evaluation add to the growing body of evidence that supports MST as an effective treatment for antisocial youth. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Thin Film Growth on Quasicrystalline Surfaces

The surfaces of quasicrystals have proved to be a very interesting playground for thin film growth. They offer a complex potential energy surface where heterogeneous nucleation of islands at specific quasilattice sites is frequently observed. These islands tend to locally adopt the symmetry of the quasicrystalline substrate. For some specific adsorbates, a complete 2-dimensional quasiperiodic metal overlayer is even formed. Other interesting phenomena are also observed in the multilayer regime. This includes the formation of novel structures, like 1-dimensional quasiperiodic Cu films or Bi allotropes, the formation of nanoscale crystalline domains with 5-fold rotational epitaxy, or the occurrence of quantum size effects influencing the film morphology. This article presents a short review of some of the achievements in thin film growth on quasicrystalline surfaces that the discovery of quasicrystals by Dan Shechtman has enabled.