Influence of the nature of aggregates on the behaviour of concrete subjected to elevated temperature

An experimental study is carried out on concretes composed of three different types of aggregates: semi crushed silico-calcareous, crushed calcareous and rolled siliceous. For each aggregate type, two water/cement ratios (W/C), 0.6 and 0.3 are studied. Aggregates and concrete specimens were subjected to 300, 600 and 750 °C heating–cooling cycles. We analyse the evolution of thermal, physical and mechanical properties of concrete in terms of behaviour and physical characteristic evolutions of aggregates with temperature. The study of thermal behaviour of aggregates showed the importance of initial moisture state for the flints. The crystallisation and microstructure of quartz play an important role in the thermal stability of siliceous aggregates. The residual mechanical behaviour of concrete varies depending on the aggregate and the influence of aggregates is also dependent on paste composition. This study allowed to better understand the influence of chemical and mineralogical characteristics of aggregates on the thermomechanical behaviour of concrete.     

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)     

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)     

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)     

Effects of material thickness and processing method on poly(lactic-co-glycolic acid) degradation and mechanical performance

In this study, the effects of material thickness and processing method on the degradation rate and the changes in the mechanical properties of poly(lactic-co-glycolic acid) material during simulated physiological degradation were investigated. Two types of poly(lactic-co-glycolic acid) materials were considered: 0.12?mm solvent-cast films and 1?mm compression-moulded plates. The experimental results presented in this study were compared to the experimental results of Shirazi et al. (Acta Biomaterialia 10(11):4695–703, 2014) for 0.25?mm solvent-cast films. These experimental observations were used to validate the computational modelling predictions of Shirazi et al. (J Mech Behav Biomed Mater 54: 48–59, 2016) on critical diffusion length scale and also to refine the model parameters. The specific material processing methods considered here did not have a significant effect on the degradation rate and the changes in mechanical properties during degradation; however, they influenced the initial molecular weight and they determined the stiffness and hardness of the poly(lactic-co-glycolic acid) material. The experimental observations strongly supported the computational modelling predictions that showed no significant difference in the degradation rate and the changes in the elastic modulus of poly(lactic-co-glycolic acid) films for thicknesses larger than 100?μm.     

Latent motion spaces for full-body motion editing

We explore an approach to full-body motion editing with linear motion models, prioritized constraint-based optimization and latent-space interpolation. By exploiting the mathematical connections between linear motion models and prioritized inverse kinematics (PIK), we formulate and solve the motion editing problem as an optimization function whose differential structure is rich enough to efficiently optimize user-specified constraints within the latent motion space. Performing motion editing within latent motion spaces has the advantage of handling pose transitions and consequently motion flow by construction from single key-frame editing. To handle motion adjustments from multiple key-frame and trajectory constraints, we developed a latent-space interpolation technique by exploiting spline functions. Such an approach handles per-frame adjustments generating smooth animations, while avoiding the computational expense of joint space interpolations. We demonstrate the usefulness of this approach by editing and generating full-body reaching and walking jump animations in challenging environment scenarios.     

Cognitive specificity in emotional distress.

Cognitive approaches to emotional distress posit that specific cognitive factors are critically linked to the etiology, course, or treatment of dysfunction. Although a number of empirical studies have assessed cognitive factors in emotional disorders such as depression and anxiety, research has yet to assess these variables simultaneously and with identical cognitive measures. Using depression and test anxiety as models of dysfunctional affective states, we examined cognitive specificity on measures of information processing, attributions, automatic thinking, and cognitive interference. Results indicated a pattern of specificity showing several differences and similarities in depression and anxiety. Specifically, "purely" depressed individuals showed evidence of selectivity processing depressive information, making dysfunctional attributions, and engaging in more negative automatic thinking. "Purely" anxious individuals, on the other hand, showed evidence of selective anxious information processing and increased cognitive interference. Results are discussed in terms of a taxonomy for classifying depressive and anxious cognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Going with the Flow: Tunable Flow‐Induced Polymer Mechanochemistry

Mechanical forces can drive chemical transformations in polymers, directing reactions along otherwise inaccessible pathways, providing exciting possibilities for developing smart, responsive materials. The state‐of‐the‐art test for solution‐based polymer mechanochemistry development is ultrasonication. However, this does not accurately model the forces that will be applied during device fabrication using processes such as 3D printing or spray coating. Here, a step is taken toward predictably translating mechanochemistry from molecular design to manufacturing by demonstrating a highly controlled nozzle flow setup in which the shear forces being delivered are precisely tuned. The results show that solvent viscosity, fluid strain rate, and the nature of the breaking bond can be individually studied. Importantly, it is shown that the influence of each is different to that suggested by ultrasonication (altered quantity of chain breakage and critical polymer chain length). Significant development is presented in the understanding of polymer bond breakage during manufacturing flows to help guide design of active components that trigger on demand. Using an anthracene‐based mechanophore, the triggering of a fluorescence turn‐on is demonstrated through careful selection of the flow parameters. This work opens the avenue for programmed chemical transformations during inline manufacturing processes leading to tunable, heterogeneous final products from a single source material.