Representing Partitions on Trees

In evolutionary biology, biologists often face the problem of constructing a phylogenetic tree on a set X of species from a multiset Π of partitions corresponding to various attributes of these species. One approach that is used to solve this problem is to try instead to associate a tree (or even a network) to the multiset ΣΠ consisting of all those bipartitions {A,X − A} with A a part of some partition in Π. The rational behind this approach is that a phylogenetic tree with leaf set X can be uniquely represented by the set of bipartitions of X induced by its edges. Motivated by these considerations, given a multiset Σ of bipartitions corresponding to a phylogenetic tree on X, in this paper we introduce and study the set P(Σ) consisting of those multisets of partitions Π of X with ΣΠ = Σ. More specifically, we characterize when P(Σ) is non-empty, and also identify some partitions in P(Σ) that are of maximum and minimum size. We also show that it is NP-complete to decide when P(Σ) is non-empty in case Σ is an arbitrary multiset of bipartitions of X. Ultimately, we hope that by gaining a better understanding of the mapping that takes an arbitrary partition system Π to the multiset ΣΠ, we will obtain new insights into the use of median networks and, more generally, split-networks to visualize sets of partitions

Voice Operated Guidance Systems for Vision Impaired People: Investigating a User-Centered Open Source Model

People who have impaired vision regularly use white canes and/or guide dogs to assist in obstacle avoidance. Guide dogs can also be of limited assistance for finding the way to a remote location, known as ??wayfinding?? Several electronic devices are currently available for providing guidance to a remote location, but these tend to be expensive, or make use of a Braille interface. This project investigated the suitability of a user centered client server approach for the development of a talking GPS system intended to fill a niche for outdoor wayfinding. The work resulted in a working prototype proof-of-concept system that uses a speech-recognition speech-synthesis interface. The prototype solution includes a custom web application which accesses the Google maps API. The system is intended to be scalable and extensible with additional features such as sensors for obstacle avoidance and access to web-based information such as weather, train or bus timetable information. The client server approach was found to be suitable for the development of this type of application

Beyond the EITC: The Effect of Reducing the Earned Income Tax Credit on Labor Force Participation

We examine variation in the Earned Income Tax Credit (EITC) program when households lose eligibility due to children aging out of the program. This change in eligibility offers a framework for assessing whether the aim of the program of increasing work incentives extends beyond the time recipients qualify for the EITC. We estimate the impact of reducing the EITC on mothers’ labor force participation using a combination of difference-in-differences and household fixed effects models, using data from the National Longitudinal Survey of Youth 1979. The results indicate that some of those who most likely qualify for the EITC (unmarried, less educated mothers) leave the workforce when they lose the benefit

Method for increasing the energy efficiency of wirelessly networked ambulatory health monitoring devices

In-home healthcare applications that use wearable devices ordinarily have strict power constraints due to the small size of the battery in the device. The power constraints are a key driver of research to develop new methods for improving the energy efficiency of ambulatory health monitoring devices. The radio-communication components typically consume a large proportion of the available energy in systems such as these. Given that radio transmissions use far more power than on-board processing, it is proposed that energy can be conserved by performing fall detection at the node. The proposed algorithm is intended to be performed at the node and provide a suitable balance between power consumption and detection accuracy. The research and prototype system described in this article focuses on wearable fall detection devices to be used elderly people who are living in non-hospital settings, and discusses considerations arising from the development of a prototype system. The outcomes of the system design and development process are discussed, and conclusions are drawn concerning the potential of the method to improve the energy efficiency of fall detection systems