Exploring Graphs with Time Constraints by Unreliable Collections of Mobile Robots

A graph environment must be explored by a collection of mobile robots. Some of the robots, a priori unknown, may turn out to be unreliable. The graph is weighted and each node is assigned a deadline. The exploration is successful if each node of the graph is visited before its deadline by a reliable robot. The edge weight corresponds to the time needed by a robot to traverse the edge. Given the number of robots which may crash, is it possible to design an algorithm, which will always guarantee the exploration, independently of the choice of the subset of unreliable robots by the adversary? We find the optimal time, during which the graph may be explored. Our approach permits to find the maximal number of robots, which may turn out to be unreliable, and the graph is still guaranteed to be explored. We concentrate on line graphs and rings, for which we give positive results. We start with the case of the collections involving only reliable robots. We give algorithms finding optimal times needed for exploration when the robots are assigned to fixed initial positions as well as when such starting positions may be determined by the algorithm. We extend our consideration to the case when some number of robots may be unreliable. Our most surprising result is that solving the line exploration problem with robots at given positions, which may involve crash-faulty ones, is NP-hard. The same problem has polynomial solutions for a ring and for the case when the initial robots' positions on the line are arbitrary. The exploration problem is shown to be NP-hard for star graphs, even when the team consists of only two reliable robots

Estimation of thorax shape for forward modelling in lungs EIT

The thorax models for pre-term babies are developed based on the CT scans from new-borns and their effect on image reconstruction is evaluated in comparison with other available models

GameUp: Exergames for mobility – a project to keep elderly active

A big challenge for Europe is the demographic shift towards an aging population. Resources in the health care sector are limited, so it is important that the seniors of tomorrow will be able to stay healthy and manage themselves as long as possible, preferably also with a good quality of life. Physical activity is very important both for mobility and for the general well-being, but it can be hard to find motivation to exercise alone at home. Also in rehabilitation there is a need for a more engaging approach than a sheet of paper describing exercises that should be performed. In the GameUp project we developed fun and motivational exergames particularly targeting elderly in a user centred approach. Physiotherapists ensured that the movements and exercises were good for flexibility, leg strength and balance. In addition to seven Kinect games, a walking app and a professional portal were developed. The Kinect games can be played in several levels, and those who are at risk of falling are able to play while seated. The professional portal ensures that the results of the project also can be used as a tool in rehabilitation. Test results from 20 elderly aged 65-95 as well as clinical trials of adherence to the exercises are encouraging, and the international and multidisciplinary team behind the project is now looking for ways to commercialize the project outcomes

Bun splitting: a practical cutting stock problem

We describe a new hierarchical 2D-guillotine Cutting Stock Problem. In contrast to the classic cutting stock problem, waste is not an issue. The problem relates to the removal of a defective part and assembly of the remaining parts into homogeneous size blocks. The context is the packing stages of cake manufacturing. The company's primary objective is to minimise total processing time at the subsequent, packing stage. This objective reduces to one of minimising the number of parts produced when cutting the tray load of buns. We offer a closed form optimization approach to this class of problems for certain cases, without recourse to mathematical programming or heuristics. The methodology is demonstrated through a case study in which the number of parts is reduced by almost a fifth, and the manufacturer's subsidiary requirement to reduce isolated single bun parts and hence customer complaints is also satisfied

Emulation of scan paths in sequential circuit synthesis

Scan paths are generally added to a sequential circuit in a final design for testability step. We present an approach to incorporate the behavior of a scan path during circuit synthesis, thus avoiding to implement the scan path shift register as a separate structural entity. The shift transitions of the scan path are treated as a part of the system functionality. Depending on the minimization strategy for the system logic, either the delay or the area of the circuit can be reduced compared to a conventional scan path. which may be interpreted as a special case of realizing the combinational logic. The approach is also extended to partial scan paths. It is shown that the resulting structure is fully testable and test patterns can be efficiently produced by a combinational test generator. The advantages of the approach are illustrated with a collection of finite state machine examples

“Knowledge I seek because culture doesn’t work anymore … It doesn’t work, death comes”: the experiences of third-generation female caregivers (gogos) in South Africa discussing sex, sexuality and HIV and AIDS with children in their care

Background Sexual reproductive health communication between parents and children has been shown to promote safer sexual choices. In many South African households, third-generation female caregivers, often grandmothers or other older females, locally known as gogos, are primary caregivers of children due to parents being deceased or absent. Subsequently, the responsibility of talking about sex and related issues has shifted to these gogos. This study explored the experiences of gogos living in Alexandra, Johannesburg on talking about sex, sexuality and HIV and AIDS with children aged 10–18 years that are in their care. Methods Ten primary caregivers were purposively selected. Data were collected through in-depth individual interviews. Thematic analysis was performed and inductive codes and themes identified. Results All gogos selected found it difficult to discuss sex, sexuality and HIV and AIDS due to culture and traditional values impacting on personal experiences as well as generation and gender barriers. Perceived low self-efficacy due to low levels of knowledge and limited skills in speaking about sex, sexuality and HIV and AIDS also contributed to low levels of sexual reproductive health communication. Conclusions This study highlights the need for interventions that focus on improving gogos’ knowledge about sexual reproductive health in addition to providing them with the skills to talk about sex, sexuality and HIV and AIDS with children in their care

Leading indicators of fiscal distress: evidence from extreme bounds analysis

Early warning systems (EWSs) are widely used to assess a country’s vulnerability to fiscal distress. A fiscal distress episode is identified as a period when government experiences extreme funding difficulties. Most EWSs employ a specific set of only fiscal leading indicators predetermined by the researchers, which casts doubt on their robustness. We revisit this issue using extreme bounds analysis, which allows identifying robust leading indicators of fiscal distress from a large set. A robust leading indicator’s effect does not strongly depend on the model specification. Consistent with the theoretical predictions of latest generation crisis models, we find that both fiscal and non-fiscal leading indicators are robust. In addition, we find that a fiscal vulnerability indicator based on fiscal and non-fiscal leading indicators offers a 29% gain in predictive power compared to a traditional one based only on fiscal leading indicators. This suggests that both fiscal and non-fiscal leading indicators should be taken into account when assessing country’s vulnerability to fiscal distress

Medico-Legal Findings, Legal Case Progression, and Outcomes in South African Rape Cases: Retrospective Review

Rachel Jewkes and colleagues examine the processing of rape cases by South African police and courts and show an association between documentation of ano-genital injuries, trials commencing, and convictions in rape cases