SUPERMARKET PATRONAGE: AN ANALYSIS OF CUSTOMER COUNTS AMONG OUTLETS WITHIN A GEOGRAPHIC AREA

As new supermarket management tools are introduced, the need for an improved understanding of store patronage is growing. Weekly customer counts for five supermarkets located in a Southeastern metropolitan area covering 261 weeks are analyzed. Descriptive statistics indicate that food shopper patterns vary by outlet. Regression equations are estimated for each location. Results point to store specific relationships. They indicate that evaluation of television and radio ads and double couponing can be quite involved.Consumer/Household Economics,

Projections of determinantal point processes

In computer experiments setting, space-filling designs are used to produce inputs, viewed as point patterns. A first important property of the design is that the point pattern covers regularly the input space. A second property is the conservation of this regular covering if the point pattern is projected onto a lower dimensional space. According to the first requirement, it seems then natural to consider classes of spatial point process which generate repulsive patterns. The class of determinantal point processes (DPPs) is considered in this paper. In particular, we address the question: Can we construct a DPP such that any projection on a lower-dimensional space remains a DPP, or at least remains repulsive? By assuming a particular form for the kernel defining the DPP, we prove rigorously that the answer is positive. We propose several examples of models, and in particular stationary models, achieving this property. These models defined on a compact set of $\mathbb{R}^d$ are shown to be efficient for Monte-Carlo integration problems; we show that the same initial spatial design, defined in $\mathbb{R}^d$, can be used to efficiently estimate integrals of $\mathbb{R}^\omega$-valued for any $\omega=1,\dots,d$

Corporate Social Reporting in Libya: A Research Note

Purpose Not enough is known about social accounting disclosure practices in developing countries. This research note adds strength and depth to the few other studies that take Libya as a point of departure to understanding the dynamic between disclosure practices and the context in which they are performed. Design/methodology/approach A sample of 270 annual reports from 54 companies, both public and private across a range of sectors and covering a five year period (2001-2005) were analysed using content analysis to ascertain patterns and trends in corporate social reporting by Libyan companies. Findings Libyan companies generally disclose some information related to social responsibility but at a low level compared with developed countries and only in certain areas. This situation changed little over the five year period under scrutiny. Research limitations/implications During the five year period examined, CSR remained largely unresponsive to significant changes in the political scene that occurred over a much longer period of time. This suggests further research is needed to illuminate the role and influence of societal culture and to understand the impact of organisational subculture on disclosure and responsibility practices. Originality/value Libya provides a point of departure for further research into other transitioning or developing economies, particularly those in the Arab world. It also offers unique insights and the possibility for comparative studies between them due to its particular character. This note augments and adds depth to other studies in the area

Detectability of extrasolar moons as gravitational microlenses

We evaluate gravitational lensing as a technique for the detection of extrasolar moons. Since 2004 gravitational microlensing has been successfully applied as a detection method for extrasolar planets. In principle, the method is sensitive to masses as low as an Earth mass or even a fraction of it. Hence it seems natural to investigate the microlensing effects of moons around extrasolar planets. We explore the simplest conceivable triple lens system, containing one star, one planet and one moon. From a microlensing point of view, this system can be modelled as a particular triple with hierarchical mass ratios very different from unity. Since the moon orbits the planet, the planet-moon separation will be small compared to the distance between planet and star. Such a configuration can lead to a complex interference of caustics. We present detectability and detection limits by comparing triple-lens light curves to best-fit binary light curves as caused by a double-lens system consisting of host star and planet -- without moon. We simulate magnification patterns covering a range of mass and separation values using the inverse ray shooting technique. These patterns are processed by analysing a large number of light curves and fitting a binary case to each of them. A chi-squared criterion is used to quantify the detectability of the moon in a number of selected triple-lens scenarios. The results of our simulations indicate that it is feasible to discover extrasolar moons via gravitational microlensing through frequent and highly precise monitoring of anomalous Galactic microlensing events with dwarf source stars.Comment: 14 pages, 11 figures. Updated to A&A published version: updated references, 1 additional illustration (Fig. 10), further analogies to solar system and extended discussio

Airflow around conic tensile membrane structures

Sophisticated analytical models and computer software have facilitated the structural design of tensile membrane structures and this has produced a diverse and complex range of design and form solutions. The climate inside a typical fabric membrane enclosure is dependent on factors such as the shape (having a significant clear height) and the thermal properties of the thin “skin”, which differ considerably from traditional or more conventional “heavy” construction. However, there has been little consideration of the effect that these forms “shapes” have on their immediate environment, from the point of view of human comfort, even for the most basic of shapes. Tensile membrane structures can have an attractive dramatic effect and easily span a large area. In addition to the lighting and shading functions normally associated with tensile membrane skins, the topology of the construction type offers exciting opportunities to lend additional functionality and higher levels of comfort to the enclosure (ElNokaly et al, 2002). This paper describes the results of wind tunnel visualization and monitoring of the airflow patterns around and under conic tensile membrane structures covering open and semi-enclosed spaces. The experiments were conducted using a number of physical models representing a simple conical membrane structure. The study was designed primarily in order to ascertain the potential of conic membranes for modifying the microclimate and improving human comfort in their immediate vicinity. (Continued