An integrated systems biology approach to understanding the rules of keratinocyte colony formation.

Closely coupled in vitro and in virtuo models have been used to explore the self-organization of normal human keratinocytes (NHK). Although it can be observed experimentally, we lack the tools to explore many biological rules that govern NHK self-organization. An agent-based computational model was developed, based on rules derived from literature, which predicts the dynamic multicellular morphogenesis of NHK and of a keratinocyte cell line (HaCat cells) under varying extracellular Ca++ concentrations. The model enables in virtuo exploration of the relative importance of biological rules and was used to test hypotheses in virtuo which were subsequently examined in vitro. Results indicated that cell-cell and cell-substrate adhesions were critically important to NHK self-organization. In contrast, cell cycle length and the number of divisions that transit-amplifying cells could undergo proved non-critical to the final organization. Two further hypotheses, to explain the growth behaviour of HaCat cells, were explored in virtuo-an inability to differentiate and a differing sensitivity to extracellular calcium. In vitro experimentation provided some support for both hypotheses. For NHKs, the prediction was made that the position of stem cells would influence the pattern of cell migration post-wounding. This was then confirmed experimentally using a scratch wound model.     

A High Performance 700?GHz Feed Horn

We present a design of a high performance horn operating at 700 GHz. The feed, which comprises three smooth-walled conical sections, is easy to machine and yet has comparable performance to a corrugated horn. The measured radiation patterns show high main beam circularity, low sidelobe level and good agreement with theoretical predictions. The cross-polar level is below −20 dB across a frequency bandwidth of 140 GHz. The new design allows the fabrication of high performance, large format feed arrays cheaply and rapidly.     

Reliability by design in distributed power transmission networks

The system operator of a large power transmission network must ensure that power is delivered whenever there is demand in order to maintain highly reliable electric service. To fulfill this mandate, the system operator must procure reserve capacity to respond to unforeseen events such as an unexpected surge in demand. This paper constructs a centralized optimal solution for a power network model by generalizing recent techniques for the centralized optimal control of demand-driven production systems. The optimal solution indicates how reserves must be adjusted according to environmental factors including variability, and the ramping-rate constraints on generation. Sensitivity to transmission constraints is addressed through the construction of an effective cost on an aggregate model.     

An analysis of urban thermal characteristics and associated land cover in Tampa Bay and Las Vegas using Landsat satellite data

Remote sensing data from both Landsat 5 and Landsat 7 systems were utilized to assess urban area thermal characteristics in Tampa Bay watershed of west-central Florida, and the Las Vegas valley of southern Nevada. To quantitatively determine urban land use extents and development densities, sub-pixel impervious surface areas were mapped for both areas. The urban-rural boundaries and urban development densities were defined by selecting certain imperviousness threshold values and Landsat thermal bands were used to investigate urban surface thermal patterns. Analysis results suggest that urban surface thermal characteristics and patterns can be identified through qualitatively based urban land use and development density data. Results show the urban area of the Tampa Bay watershed has a daytime heating effect (heat-source), whereas the urban surface in Las Vegas has a daytime cooling effect (heat-sink). These thermal effects strongly correlated with urban development densities where higher percent imperviousness is usually associated with higher surface temperature. Using vegetation canopy coverage information, the spatial and temporal distributions of urban impervious surface and associated thermal characteristics are demonstrated to be very useful sources in quantifying urban land use, development intensity, and urban thermal patterns.     

Planning Against Long Term Water Scarcity: A Fuzzy Multicriteria Approach

The study presents a multicriteria method incorporating a fuzzy set approach and the 0/1 programming for selecting the most appropriate actions for facing long term water scarcity in a water system under a set of objectives and constraints. The proposed method includes also the right of veto which can be utilised under certain extreme conditions or for securing commensurate solutions. The proposed method is applied for devising the technical component of a rational preparedness plan against long term water scarcity in the island of Naxos, Cyclades (Greece).     

In-situ methods for the determination of current distributions in PEM fuel cells

This article describes three different techniques for the determination of the current density distribution in operating fuel cells and compares their relative benefits with respect to ease of implementation and information gain. Real-time current density distribution data under steady state as well as transient conditions are presented and it is shown that they can contribute to an improved understanding of water management and reactant distribution over the active fuel cell area. The importance of these factors for the optimisation of fuel cell performance is discussed.     

多处理器设计技术探计

人们可以将多处理器设计定义为这样的系统:它把各项功能和任务分配给多个处理器去完成,而这些处理器彼此协调、互相沟通,以保证行为一致.多处理器系统比单处理器设计更加复杂.它要求为内务操作和协调功能进行额外的编程,调试也更为复杂.这是因为多处理器系统需要各处理器间的交互作用,而在单处理器体系结构中不存在这种处理器之间的交互作用的问题.尽管多处理器设计增加了复杂性,但多年来,它一直用于高性能计算机和工作站中,而且正跻身于日益增多的嵌入式系统应用之中.     

虚拟机和随机调度技术简化无线设计

一种新的无线设计方法使设计师们能将多种基于分组的标准融合到资源受限的手机硬件中.