The lowest crossing in 2D critical percolation

We study the following problem for critical site percolation on the triangular lattice. Let A and B be sites on a horizontal line e separated by distance n. Consider, in the half-plane above e, the lowest occupied crossing R from the half-line left of A to the half-line right of B. We show that the probability that R has a site at distance smaller than m from AB is of order (log (n/m))^{-1}, uniformly in 1 <= m < n/2. Much of our analysis can be carried out for other two-dimensional lattices as well.Comment: 16 pages, Latex, 2 eps figures, special macros: percmac.tex. Submitted to Annals of Probabilit

Die plek en funksle van bestuur in die kerk

The place and function of management in the churchIn this article attention is given to general management as a solution to the current management problem in congregations. Management as a science is not unfamiliar in the church, but it has merely been neglected. The meaning of the term “church" as used in both the Old Testament and the New Testament is examined. Management within the church will have to uphold the nature, being, character, purpose and structure of the congregation according to the Word of God. Management will have to be a process by which believers continuously engage in congregational activities, try to use human and other resources as efficiently as possible, in order to fulfil all the ministry needs o f the congregation and to achieve specific goals. To be able to achieve this, the basic management tasks of planning, organising, activating and controlling have to be undertaken. The church should apply management principles to enable the church to become what it should be according to the will/intention of God

The whole truth and nothing but the truth, but what is the truth?

The moral aspects of genetic counselling are explored in situations where the outcome of a DNA test does not lead to certain knowledge. The most frequent type of interaction between counsellor and counsellee is when factual information is given, but sometimes "factual" information is difficult to obtain. How do counsellors deal with "uncertain" knowledge in genetics? Arguments and assumptions are presented and the finding of a 27 CAG repeat in the Huntington gene is used as an example. However, the questions "how far does the duty to inform reach?" and "to what extent is the doctor responsible?" are important in the whole field of genetics, and will be even more important in the future. The aims of science and clinical practice are discussed; we conclude that counsellors run the risk of taking on an infinite responsibility

’n Bestuurshulpmiddel vir doelmatige en doeltreffende kerkbestuur: ’n Generiese perspektief vir ’n makro-gemeente

A management tool for efficient and effective church management: A generic perspective for a macro-congregation This article examines the place and function of project management as a generic management tool in the church and the potential solution it has to offer in respect of congregation management and ministry. "Project" and "project management" are defined and contextualised within a church environment. The project management process is put in the context of a project management system and of the congregation and its relevant functions. Project management consists of five generic phases namely, project initiation, project planning, project execution, project control and project closure. The project manager is provided with an overall picture of the project management process, with specific reference to its compilation and workings. The discussion in the article includes the management of the human dimension of the project management process

Snellere afbraak organische stof op duinzandgrond

In 2008 en 2009 is bij PRI en PPO in Lisse onderzoek gedaan naar de afbraaksnelheid van organische stof op duinzandgronden. Op het veld en in het laboratorium is uitgebreid gemeten. Tussen de afbraak op diverse gronden blijken verschillen te bestaan. In dit artikel de stand van zaken na twee jaa

Locating helicopter emergency medical service bases to optimise population coverage versus average response time

__Background:__ New South Wales (NSW), Australia has a network of multirole retrieval physician staffed helicopter emergency medical services (HEMS) with seven bases servicing a jurisdiction with population concentrated along the eastern seaboard. The aim of this study was to estimate optimal HEMS base locations within NSW using advanced mathematical modelling techniques. __Methods:__ We used high resolution census population data for NSW from 2011 which divides the state into areas containing 200-800 people. Optimal HEMS base locations were estimated using the maximal covering location problem facility location optimization model and the average response time model, exploring the number of bases needed to cover various fractions of the population for a 45 min response time threshold or minimizing the overall average response time to all persons, both in green field scenarios and conditioning on the current base structure. We also developed a hybrid mathematical model where average response time was optimised based on minimum population coverage thresholds. __Results:__ Seven bases could cover 98% of the population within 45mins when optimised for coverage or reach the entire population of the state within an average of 21mins if optimised for response time. Given the existing bases, adding two bases could either increase the 45 min coverage from 91% to 97% or decrease the average response time from 21mins to 19mins. Adding a single specialist prehospital rapid response HEMS to the area of greatest population concentration decreased the average state wide response time by 4mins. The optimum seven base hybrid model that was able to cover 97.75% of the population within 45mins, and all of the population in an average response time of 18 mins included the rapid response HEMS model. __Conclusions:__ HEMS base locations can be optimised based on either percentage of the population covered, or average response time to the entire population. We have also demonstrated a hybrid technique that optimizes response time for a given number of bases and minimum defined threshold of population coverage. Addition of specialized rapid response HEMS services to a system of multirole retrieval HEMS may reduce overall average response times by improving access in large urban areas

On the asymptotic density in a one-dimensional self-organized critical forest-fire model

Consider the following forest-fire model where the possible locations of trees are the sites of $bold$. Each site has two possible states: `vacant' or `occupied'. Vacant sites become occupied at rate $1$. At each site ignition (by lightning) occurs at ignition rate $lambda$, the parameter of the model. When a site is ignited, its occupied cluster becomes vacant instantaneously. In the literature similar models have been studied for discrete time, finite (but large) volume and finite (but large) speed at which the fire spreads out. The most interesting behaviour seems to occur when the ignition rate goes to $0$, as this allows clusters to grow very large before being hit by lightning. It has been stated by Drossel, Clar and Schwabl (1993) that then (in our notation) the density of vacant sites (in equilibrium) is of order $1 / log(1 / lambda)$. Their proof uses a `scaling ansatz' and is not rigorous. We give, for our version of the model, a rigorous and mathematically more natural proof. Our proof shows that regardless of the initial configuration, already after time of order $log(1 / lambda)$ the density is of the above mentioned order $1 / log(1 / lambda)$. We also point out how our proof can be modified for the model studied by Drossel et al

Model-driven quality and resource management for CPSs

A Cyber-Physical System (CPS) integrates cyber systems, human users, networks and physical systems. Thus, a CPS needs visual context and awareness to make autonomous and correct decisions. Advanced image and video processing is computationally intensive and challenging. Moreover, a CPS comprises increasingly complex and distributed configurations, which is reflectedin the growing number of sensors, actuators and other smart devices. This leadsto an exponential number of dynamic system configurations. To make mattersworse, a CPS needs to simultaneously satisfy many rigorous constraints, e.g.,hard deadlines, safety, quality, and performance. Hence, the system designeris confronted with an immense number of potential configurations of which anumber meet the constraints and only a fraction are optimal regarding certainqualities. This makes finding the optimal configurations hard, especially duringrun-time. A domain-specific language (DSL) for quality and resource managment (QRM) is presented to specify these configurations conveniently and reasonabout them in an automated manner

Collective self-build for senior friendly communities. Studying the effects on social cohesion, social satisfaction and loneliness

Neighbourhood social cohesion is important for the health and well-being of the ageing population. It is therefore crucial to study how we can create neighbourhoods with high levels of neighbourhood social cohesion where senior citizens can age in place. We test the hypotheses that collective self-build is positively related to social cohesion and (directly and indirectly) to social satisfaction and lower levels of loneliness. The study is based on survey data from 326 respondents of 50 years and over living in 25 collective self-build development projects and 19 conventionally developed housing projects in the Netherlands. The results of a structural equation model (SEM) reveal that collective self-build is directly related to neighbourhood social cohesion and lower feelings of social loneliness. We find an indirect effect on social satisfaction. These positive relationships hold while controlling for personal and household characteristics. This quantitative study adds scientific knowledge on the collective self-build development method and its relation to social cohesion, loneliness and satisfaction