BACKGROUND Several studies have examined the prevalence and pattern of substance use among medical students in Nigeria. Few of these studies have specifically examined the relationship between the psychological distress and psychoactive substance use among these students. Yet, evidence world-wide suggests that substance use among medical students might be on the rise and may be related to the l...

This paper presents a novel method for deciding the locations of “guards” required to visually inspect a given 2D workspace. The decided guard positions can then be used as control points in the path of a mobile robot that autonomously inspects a workspace. It is assumed that each of the guards (or the mobile robot that visits the guard positions in some order) is equipped with a panoramic came...

In the Eternal Domination game, a team of guard tokens initially occupies a dominating set on a graph G. A rioter then picks a node without a guard on it and attacks it. The guards defend against the attack: one of them has to move to the attacked node, while each remaining one can choose to move to one of his neighboring nodes. The new guards’ placement must again be dominating. This attack-de...

In Chapter 1 it was shown that Fisk's proof of the art gallery theorem can be converted into an algorithm that covers a polygon of n vertices with [n/3\ guards in O{n logn) time. Although [n/3\ is necessary in some cases, often this is far more guards than are needed to cover a particular polygon. For example, convex polygons only require one guard, but Avis and Toussaint's algorithm would stil...

purpose the objectives of this study include: (1) determination of the attenuation of strike acceleration that tae kwon do sparring safety pads provide from kicks from olympic style tkd fighters, (2) the sex and weight differentiation in acceleration achieved within the thorax model with the roundhouse kicks. methods this prospective, observational study utilized 15 olympic style fighters from ...

Given a graph and a single watchman, the objective of the Watchman’s Walk Problem is to find a closed dominating walk of minimum length which the watchman can traverse to efficiently guard the graph. When multiple guards are available, one natural variation is to assume fixed time constraints on the monitoring of vertices and attempt to minimize the number of guards required. We find upper boun...

In this discrete time process, guards are allowed to traverse edges of a network under the constraint that the neighbourhood of each vertex must be visited within a specified time interval t. Setting t = 0 the guards form a dominating set at all times. We show every rooted tree with relatively few leaves has a branch with a certain order and number of pendant vertices. This result is used to es...

It has long been recognised that standard process algebra has difficulty dealing with actions of different priority, such as for instance an interrupt action of high priority. Various solutions have been proposed. We introduce a new approach, involving the addition of “priority guards” to Milner’s process calculus CCS. In our approach, priority is unstratified, meaning that actions are not assi...