A Multibody Model for the Simulation of Bicycle Suspension Systems

The paper describes a two-dimensional mathematical model for the motion of a bicycle-rider system with wheel suspensions. It focusses on the prediction of vibrational stress on the rider due to uneven track. The model was evaluated by comparing its predictions with measuring data concerning weighted accelerations on the human body, depending on various bicycle designs and road surfaces. For the intended purpose the predictions for vibrational stress and vibrational behaviour are sufficiently precise, and the model turns out to be adequate for designing and developing bicycle suspensions.     

Cultural Models of Pfiesteria : Toward Cultivating More Appropriate Risk Perceptions

Based on semistructured interviews (N = 7), informal interviewing (N = 63), and a survey (N = 790), this article describes the cultural models used by mid-Atlantic residents to understand Pfiesteria piscicida. A cultural model is a simplified way of understanding a complex system, shared by members of a culture. Eighty-eight percent of respondents understood Pfiesteria using one of four previously existing cultural models: a disease in fish, a parasite in fish, a water pollutant, and a toxin or poison. These models are not used by marine biologists, who are more likely to refer to Pfiesteria taxonomically or, in its fish killing form, to call it a predator. Our survey shows that the cultural model a respondent holds is correlated significantly with his or her believed pathway of human harm (e.g., eating fish versus swimming) and is correlated significantly but weakly with his or her behavioral responses. We conclude that existing cultural models, as the public has applied them to Pfiesteria, have led people to avoid a range of coastal activities and seafoods, in virtually all cases unnecessarily. Cultural models appear to explain public reaction better than previously hypothesized factors such as inaccurate media coverage. These findings suggest an approach to developing a pedagogical and communications strategy which could provide the public with a cultural model better matched to Pfiesteria.     

Seabirds utilizing the Northeast Water polynya

A small seabird community depends on the resources of the Northeast Water (NEW) polynya. In spring, at least 1000 King Eiders and 2500 Common Eiders form pre-breeding congregations at Ob Bank before dispersing in mid June to breeding areas. The most abundant species is the Fulmar, which breeds in six colonies with a total of 2550 “apparently occupied sites”, corresponding to approx. 1475 active pairs in 1993. Kittiwakes occupied almost 900 sites at Mallemukfjeld, with an estimated 733 breeding pairs. The entire NEW area probably holds 400–500 pairs of Ivory Gulls, and about 500 individuals were associated with a colony on Henrik Krøyer Holme; this is one of the world's largest known colonies. Sabine's Gulls breed at the same islands and on Kilen (approx. 50 pairs in each place). Small colonies (total less than 1000 birds) of Arctic Terns are distributed along the edge of the polynya, with the largest colony of about 100 pairs on Henrik Krøyer Holme. The Black Guillemot is the only breeding auk species (< 20 pairs) in the area. Small numbers of Red Phalaropes were observed in the polynya in 1992 and 1993, and the species may have bred at Henrik Krøyer Holme in 1993; the polynya area may also serve as a staging area for transpolar migrants. In late summer a few hundreds of Ross's Gull—non-breeding adults and immatures—show up in and around the polynya, and in recent years a few cases of breeding have also been recorded. The relatively small seabird populations are evidence of a generally low carrying capacity of the polynya area.Apart from the benthic foraging eiders and the Black Guillemot, the seabird community of NEW consists of surface feeders—Fulmars and gulls—dependent on small fish and zooplankton. During their stay in the NEW area, the five most abundant surface feeders will annually consume approximately 243,000 kg (wet weight) of food, of which the Fulmars alone take 67%. Food demand in relation to area of open water in the polynya is highest in spring (approx. 0.2 kg/km²), which is     

Conservation and redevelopment policy for British urban dock areas

Abstract

Technological innovations in the 1960s led to fundamental changes in the location and the nature of dock and warehousing work. Cities throughout the world have adopted very different planning and development approaches to facing these changes in technology. This paper draws mainly on a survey of the British experience in order to identify common problems and suggest some ways of solving them. The first part briefly analyzes the factors which have made docklands redundant in many areas. Problems and needs as seen by local officials are then reviewed; and some of the general difficulties facing efforts to reintegrate dock areas into the larger socioeconomic systems of a city are described. Then, the alternative policies of conservation and redevelopment are discussed. Finally, future policy directions are considered.