Transforming rooted agreement into unrooted agreement

We give a simple technique that allows to transform dynamic programming type algorithms for the Maximum Agreement Subtree problem (MAST) for rooted trees into algorithms for the Maximum Agreement Subtree problem for unrooted trees (UMAST). Using this technique we obtain an O (n log n)-time algorithm for the UMAST problem for binary trees. This matches the complexity of the best known algorithm for the rooted case.     

Effects of acetabular resurfacing component material and fixation on the strain distribution in the pelvis

A 3D finite element (FE) model of an implanted pelvis was developed as part of a project investigating an all-polymer hip resurfacing design. The model was used to compare this novel design with a metal-on-metal design in current use and a metal-on-polymer design typical of early resurfacing implants. The model included forces representing the actions of 22 muscles as well as variable cancellous bone stiffness and variable cortical shell thickness. The hip joint reaction force was applied via contact modelled between the femoral and acetabular components of the resurfacing prosthesis. Five load cases representing time points through the gait cycle were analysed. The effect of varying fixation conditions was also investigated. The highest cancellous bone strain levels were found at mid-stance, not heel-strike. Remote from the acetabulum there was little effect of prosthesis material and fixation upon the von Mises stresses and maximum principal strains. Implant material appeared to have little effect upon cancellous bone strain failure with both bended and unbonded bone-implant interfaces. The unbonded implants increased stresses in the subchondral bone at the centre of the acetabulum and increased cancellous bone loading, resembling behaviour obtained previously for the intact acetabulum.     

Flocking in Fixed and Switching Networks

This note analyzes the stability properties of a group of mobile agents that align their velocity vectors, and stabilize their inter-agent distances, using decentralized, nearest-neighbor interaction rules, exchanging information over networks that change arbitrarily (no dwell time between consecutive switches). These changes introduce discontinuities in the agent control laws. To accommodate for arbitrary switching in the topology of the network of agent interactions we employ nonsmooth analysis. The main result is that regardless of switching, convergence to a common velocity vector and stabilization of inter-agent distances is still guaranteed as long as the network remains connected at all times     

Do women's provider-role attitudes moderate the links between work and family?

The authors examined the links between mothers' work qualities and their individual well-being and marital quality, as well as adolescent daughters' and sons' gender-role attitudes, as a function of mothers' provider-role attitudes, in 134 dual-earner families. In home interviews, mothers described their work, provider-role attitudes, family relationships, and mental health; their offspring reported gender-role attitudes. Women's attitudes about breadwinning were coded into main-secondary, coprovider, and ambivalent coprovider groups. Mothers' provider-role attitudes moderated the links between status indicators and mothers' depression, marital conflict, and daughters' gender-role attitudes. For example, depression and marital conflict were negatively related to coprovider mothers' earnings and occupational prestige. The same was not true for main-secondary and ambivalent coprovider mothers. These findings underscore the importance of considering employed women's interpretation of their work roles when exploring work-family links. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Indoor robot gardening: design and implementation

This paper describes the architecture and implementation of a distributed autonomous gardening system with applications in urban/indoor precision agriculture. The garden is a mesh network of robots and plants. The gardening robots are mobile manipulators with an eye-in-hand camera. They are capable of locating plants in the garden, watering them, and locating and grasping fruit. The plants are potted cherry tomatoes enhanced with sensors and computation to monitor their well-being (e.g. soil humidity, state of fruits) and with networking to communicate servicing requests to the robots. By embedding sensing, computation, and communication into the pots, task allocation in the system is de-centrally coordinated, which makes the system scalable and robust against the failure of a centralized agent. We describe the architecture of this system and present experimental results for navigation, object recognition, and manipulation as well as challenges that lie ahead toward autonomous precision agriculture with multi-robot teams.