Optimal utilisation level for lean product development in a multitasking context

Flow of information is of utmost importance during product development (PD) endeavours with timely feedback supporting the resolution of higher risk elements. PD task size, multitasking and resource utilisation levels of the PD system influence information flow and the value ultimately realised from the investment in PD. In this paper, a model incorporating a methodology developed using queuing theory, and in particular, results obtained for Jackson networks are extended to help engineering management to improve PD task flow and consequently become more ‘lean’. Considered factors include: optimal PD task size and multitasking (focus) level as well as the utilisation level of PD resources. Empirical data were collected from a case study company and compared to optimal values. The benefits of the proposed model and approaches are discussed.     

Quantitative Analysis of Tau-Microtubule Interaction Using FRET

The interaction between the microtubule associated protein, tau and the microtubules is investigated. A fluorescence resonance energy transfer (FRET) assay was used to determine the distance separating tau to the microtubule wall, as well as the binding parameters of the interaction. By using microtubules stabilized with Flutax-2 as donor and tau labeled with rhodamine as acceptor, a donor-to-acceptor distance of 54 ± 1 Å was found. A molecular model is proposed in which Flutax-2 is directly accessible to tau-rhodamine molecules for energy transfer. By titration, we calculated the stoichiometric dissociation constant to be equal to 1.0 ± 0.5 µM. The influence of the C-terminal tails of αβ-tubulin on the tau-microtubule interaction is presented once a procedure to form homogeneous solution of cleaved tubulin has been determined. The results indicate that the C-terminal tails of α- and β-tubulin by electrostatic effects and of recruitment seem to be involved in the binding mechanism of tau.     

未来十年风景园林的四个挑战

<正>欧洲和法国所经历的缓慢增长期,已经导致了市政工程费用的削减;在这种惨淡的背景下,人们可能会担心风景园林的未来。但这种担忧似乎并不合理,因为我们将面临的挑战将持久地使这门专业和从事它的人被完全认可。我们为自己和未来几代人所创建的空间品质问题比以往任何时候更加突出。自然资源是有限的,应予以保护。如果我们要养活不断增长的人口,那么农业用地的保护也至关重要。气候变化是必然的,我们也应为其做准备。而且,在持续不断的危机下我们的社会已经变得脆弱,我们应该与社会分化抗争,它实质上也是空间分化。在未来10年,风景园林设计师将面对4     

Chemical reactivity of mineral aggregates in aqueous solution: relationship with bitumen emulsion breaking

This paper reports a study on chemical reactivity of gneiss, diorite and limestone aggregates in aqueous solution. The originality of this study is that it extended to very short times (less than 1440 min). Rise in pH tests was implemented and dissolution kinetics was analysed. The results showed that calcium was the major element released by the aggregates. It has also been found that dissolution had an influence on the final morphology of aggregates. Polyamine emulsifier adsorption onto aggregates has been assessed using electrophoresis. Finally, the rise in pH and electrophoretic tests were compared to the breaking test traditionally performed to characterise bitumen emulsions. It was found that breaking values were controlled by both the surface area and the surface charge of the particles. Results may be correlated to polyamine adsorption on aggregates. Adsorption seemed to be efficient for gneiss and diorite: at pH 2, their charge turned from slightly negative to highly positive. At this pH value, limestone particles were dissolved and polyamine adsorption must be less efficient than with gneiss and diorite, for which the emulsion breaking was facilitated by the high attraction of particles for the emulsifier, due to their negative surface charge.     

Validation of a new self-report measure of parental attributions.

Attributional theory and empirical evidence suggest that a tendency to make stable, global self-causal attributions for undesirable events is associated with negative outcomes. However, existing self-report measures of parental attributions do not account for the possibility that dysfunctional parent-causal attributions for child misbehavior might be important predictors of poor family functioning. To address these concerns, the authors developed and tested a new measure of both parent-causal and child-responsible attributions for child misbehavior in a sample of 453 community couples. Structural validity, convergent validity, discriminant validity, internal consistency, and temporal stability of the new measure were examined. As expected, confirmatory factor analysis resulted in 2 factors, Child-Responsible (9 items) and Parent-Causal (7 items); the final model was cross-validated in a holdout sample. The final scale demonstrated adequate internal consistency (αs = .81–.90), test–retest reliability (rs = .55–.76), and convergent and discriminant validity. Dysfunctional parent-causal and child-responsible attributions significantly predicted parental emotional problems, ineffective discipline, parent–child physical aggression, and low parenting satisfaction. Associations with parent–child aggression and parenting satisfaction were generally larger than with partner aggression and relationship satisfaction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Forming Nanocrystalline Structures in Metal Particle Impact

Grain refinement by plastic deformation is becoming increasingly popular as a way of producing metals with improved properties, such as higher mechanical strength. Surface treatment techniques in which a metallic substrate is bombarded with metallic particles can generate nanocrystalline layers in the impact zone. Understanding the physical mechanisms underlying this grain refinement is crucial for achieving an improvement of existing experimental processes. In this article, we propose a numerical framework combining finite element (FE) simulations with a dislocation-based material model to predict the evolution of the microstructure under particle impact. A single particle normally impacting on a metallic substrate was simulated at different initial velocities. The simulations were compared with previously reported numerical and experimental data. The results indicate that our model accurately captures the grain refinement in the impact zone for a broad range of velocities. This approach provides valuable information on the formation of nanocrystalline layers in both the substrate and the impacting particle. Its potential applications include processes involving surface treatment by high velocity particles, such as shot peening, surface mechanical attrition treatment, kinetic metallization, cold spray, etc.     

Modeling heterogeneous bacterial populations exposed to antibiotics: The logistic‐dynamics case

In typical in vitro tests for clinical use or development of antibiotics, samples from a bacterial population are exposed to an antibiotic at various concentrations. The resulting data can then be used to build a mathematical model suitable for dosing regimen design or for further development. For bacterial populations that include resistant subpopulations—an issue that has reached alarming proportions—building such a model is challenging. In prior work, we developed a related modeling framework for such heterogeneous bacterial populations following linear dynamics when exposed to an antibiotic. We extend this framework to the case of logistic dynamics, common among strongly resistant bacterial strains. Explicit formulas are developed that can be easily used in parameter estimation and subsequent dosing regimen design under realistic pharmacokinetic conditions. A case study using experimental data from the effect of an antibiotic on a gram‐negative bacterial population exemplifies the usefulness of the proposed approach. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2385–2393, 2015