Genetic evidence of a strong functional constraint of neurotrypsin during primate evolution

Neurotrypsin is one of the extra-cellular serine proteases that are predominantly expressed in the brain and involved in neuronal development and function. Mutations in humans are associated with autosomal recessive non-syndromic mental retardation (MR). We studied the molecular evolution of neurotrypsin by sequencing the coding region of neurotrypsin in 11 representative non-human primate species covering great apes, lesser apes, Old World monkeys and New World monkeys. Our results demonstrated a strong functional constraint of neurotrypsin that was caused by strong purifying selection during primate evolution, an implication of an essential functional role of neurotrypsin in primate cognition. Further analysis indicated that the purifying selection was in fact acting on the SRCR domains of neurotrypsin, which mediate the binding activity of neurotrypsin to cell surface or extracellular proteins. In addition, by comparing primates with three other mammalian orders, we demonstrated that the absence of the first copy of the SRCR domain (exon 2 and 3) in mouse and rat was due to the deletion of this segment in the murine lineage. Copyright (C) 2005 S. Karger AG, Basel.

Mechanical constraint and loading on ferroelectric memory capacitors

The influence of mechanical constraint imposed by device geometry upon the switching response of a ferroelectric thin film memory capacitor is investigated. The memory capacitor was represented by two-dimensional ferroelectric islands of different aspect ratio, mechanically constrained by surrounding materials. Its ferroelectric non-linear behaviour was modeled by a crystal plasticity constitutive law and calculated using the finite element method. The switching response of the device, in terms of remnant charge storage, was determined as a function of geometry and constraint. The switching response under applied in-plane tensile stress and hydrostatic pressure was also studied experimentally. Our results showed that (1) the capacitor's aspect ratio could significantly affect the clamping behaviour and thus the remnant polarization, (2) it was possible to maximise the switching charge through the optimisation of the device geometry, and (3) it is possible to find a critical switching stress at zero electric field and a critical coercive field at zero residual stress. © 2009 Materials Research Society.

Effects of constraint curvature on structural instability: tensile buckling and multiple bifurcations

Bifurcation of an elastic structure crucially depends on the curvature of the constraints against which the ends of the structure are prescribed to move, an effect which deserves more attention than it has received so far. In fact, we show theoretically and we provide definitive experimental verification that an appropriate curvature of the constraint over which the end of a structure has to slide strongly affects buckling loads and can induce: (i.) tensile buckling; (ii.) decreasing- (softening), increasing- (hardening), or constant-load (null stiffness) postcritical behaviour; (iii.) multiple bifurcations, determining for instance two bifurcation loads (one tensile and one compressive) in a single-degree-of-freedom elastic system. We show how to design a constraint profile to obtain a desired postcritical behaviour and we provide the solution for the elastica constrained to slide along a circle on one end, representing the first example of an inflexional elastica developed from a buckling in tension. These results have important practical implications in the design of compliant mechanisms and may find applications in devices operating in quasi-static or dynamic conditions.

A starting point for addressing product innovativeness in the Fuzzy Front-End

Product innovativeness is a primary contingent factor to be addressed for the development of flexible management for the front-end. However, due to complexity of this early phase of the innovation process, the definition of which attributes to customise is critical to support a contingent approach. Therefore, this study investigates front-end attributes that need to be customised to permit effective management for different degrees of innovation. To accomplish this aim, a literature review and five case studies were performed. The findings highlighted the front-end strategic and operational levels as factors influencing the front-end attributes related to product innovativeness. In conclusion, this study suggests that two front-end attributes should be customised: development activities and decision-making approach. Copyright © 2011 Inderscience Enterprises Ltd.

Neuro-Fuzzy genetic system for selection of construction project managers

Choosing a project manager for a construction project—particularly, large projects—is a critical project decision. The selection process involves different criteria and should be in accordance with company policies and project specifications. Traditionally, potential candidates are interviewed and the most qualified are selected in compliance with company priorities and project conditions. Precise computing models that could take various candidates’ information into consideration and then pinpoint the most qualified person with a high degree of accuracy would be beneficial. On the basis of the opinions of experienced construction company managers, this paper, through presenting a fuzzy system, identifies the important criteria in selecting a project manager. The proposed fuzzy system is based on IF-THEN rules; a genetic algorithm improves the overall accuracy as well as the functions used by the fuzzy system to make initial estimates of the cluster centers for fuzzy c-means clustering. Moreover, a back-propagation neutral network method was used to train the system. The optimal measures of the inference parameters were identified by calculating the system’s output error and propagating this error within the system. After specifying the system parameters, the membership function parameters—which by means of clustering and projection were approximated—were tuned with the genetic algorithm. Results from this system in selecting project managers show its high capability in making high-quality personnel predictions

Optimal constraint tightening policies for robust variable horizon model predictive control

This paper develops a technique for improving the region of attraction of a robust variable horizon model predictive controller. It considers a constrained discrete-time linear system acted upon by a bounded, but unknown time-varying state disturbance. Using constraint tightening for robustness, it is shown how the tightening policy, parameterised as direct feedback on the disturbance, can be optimised to increase the volume of an inner approximation to the controller's true region of attraction. Numerical examples demonstrate the benefits of the policy in increasing region of attraction volume and decreasing the maximum prediction horizon length. © 2012 IEEE.

东湖生态系统污染状况的FUZZY聚类分析

以水色、透明度、五日生化需氧量、总氮、总磷、悬浮物等感官的和生物学的6个参数为依据,用fuzzy聚类分析方法对武汉东湖生态系统的污染状况进行了分析研究,所获得的结果与实际情况相符。同时也简单地介绍和讨论了用于生态学的fuzzy聚类分析的一般方法。