How can firms profitably give away free products? This paper provides a novel answer and articulates tradeoffs in a space of information product design. We introduce a formal model of two-sided network externalities based in textbook economics—a mix of Katz & Shapiro network effects, price discrimination, and product differentiation. Externality-based complements, however, exploit a different m...

A DRIVER’S RESPONSE TIME IN APPLYING THE BRAKES IN AN EMERGENCY IS COMMONLY THOUGHT TO BE IMPAIRED BY SLEEPINESS. Thus, reaction time (RT) given as a task secondary to driving has been seen to be a valid method for monitoring sleepiness, measured by means of the driver pushing a steeringwheel switch or a foot operated button in response to stimuli generated from within the vehicle. However, dri...

The article by Jayatilleke and Mackie 1 on reflective practice in public health offers a useful and timely overview of a key topical challenge for public health professionals; particularly given its current prominence in appraisal and revalidation processes. The authors advise that evidence of reflective practice is growing in allied health professions but not in public health. It may be argued...

Introduction Does the distinction between cognition and affect apply to implicit mental states? In the literature on intergroup relations, cognition and affect correspond to stereotypes— beliefs about social groups, or, more concretely, representations of traits associated with social groups (Stangor, 2009)—and prejudice—negative affective or evaluative responses toward others on the basis of s...

The maintenance of a central database of burns units and practitioners forms part of this strategy. Broader objectives include the improvement of burns care and resources in South Africa and increasing the number of practitioners to complete the Emergency Management of Severe Burns (EMSB) course. 4. McGregor JC. Major burn disasters: lessons to be learned from previous incidents and a need for ...

s+%26+Virtual+Meeting/Abstracts?&vmview;=abst_detail_view&confID;=47&abstractID;=33295; cited March 30, 2009]4. Kirkwood JM, Manola J, Ibrahim J, Sondak V, Ernstoff MS, Rao U on behalf of the Eastern Cooperative Oncology Group. A pooled analysis of Eastern Cooperative Oncology Group and Intergroup trials of adjuvant high-dose interferon for melanoma. Clin Cancer Res 2004;10:1670–7. 5. Kilbridg...

Cutaneus malignant melanoma (MM) is a highly malignant tumour of the skin and is responsible for more deaths than any other skin cancer (Imko-Walczuk et al., 2009). Melanocytes originate from the neural crest and in contrast to Langerhans' cells are located amongst the basal layer of the epidermis, hair bulb, eyes, ears, and meninges (Bandarchi et al., 2010; Fitzpatrick, 1971; Nordlund & Boissy...

This paper analyses the usage made of the journals and books offered by the BT Digital Library, looking in detail at the usage of the 3,500 people at BT’s development site at Adastral Park, near Ipswich, and the impact of this usage on purchase decisions in the library. The Digital Library offers over 800 electronic journals to its user community. Journals are held on the Library server, where ...

The new edition of Mackie and McCartney's "Practical Handbook of Bacteriology" shouli be a very useful volume for the student of bacteriology and the laboratory worker. It is divided into three sections, the first and third being devoted to immunology and general bacteriology respectively. The more important phenomena of immunity and details of the more commonly occurring bacteria are set out w...