Science Ebooks

Dummy variables are variables that take the values of only 0 or 1. They may be explanatory or outcome variables; however, the focus of this article is explanatory or independent variable construction and usage. Typically, dummy variables are used in the following applications: time series analysis with seasonality or regime switching; analysis of qualitative data, such as survey responses; categorical representation, and representation of value levels. Target domains may be economic forecasting, bio-medical research, credit scoring, response modeling, and other fields. Dummy variables may serve as inputs in traditional regression methods or new modeling paradigms, such as genetic algorithms, neural networks, or Boolean network models.

The cool-water temperate carbonate depositional realm is neither as well documented nor as well understood as the more familiar warmwater tropical domain (Nelson, 1988; James, 1997). This is largely because these sediments, formed and deposited in waters <20°C, occur in inhospitable environments that are difficult to study. Apart from southern Australia, New Zealand, and the peri-Mediterranean region, the Cenozoic record of these deposits is meager and most are buried in the subsurface. Leg 182 sites provided the opportunity for new insights into the spatial and temporal aspects of temperate carbonate deposition in shelf edge and upper slope environments.

Six Strombus species 1 inhabit the shallow coastal waters of Florida and the Caribbean region: Strombus gigas Linnaeus (queen conch), S. costatus Gmelin (milk conch), S. raninus Gmelin (hawk-wing conch), S. alatus Gmelin (Florida fighting conch), S. pugilis Linnaeus (West Indian fighting conch) and S. gallus Linnaeus (rooster-tail conch; Abbott 1974). Of these species, S. gigas holds the highest commercial value as a subsistence and commercial fisheries product (Berg 1976, Brownell 1977, Appeldoorn 1994). S. costatus is also a highly valued fisheries species in Mexico (Aldana-Aranda et al. 1989).

Hydrogen is used in a number of industrial applications, with today‘s largest consumers being ammonia production facilities (40.3%), oil refineries (37.3%), and methanol production plants (10.0%). In1996, three trillion cubic feet of hydrogen were consumed in the United States (SRI, 1998). International consumption of hydrogen follows a similar trend, with ammonia production accountingfor62.4% of the world‘s hydrogen, and refining and methanol production consuming 24.3% and 8.7%, respectively. Because such large quantities of hydrogen are required in these instances, the hydrogen is generally produced by the consumer, and the most common method is steam reforming of natural gas.

« We must at the outset distinguish basic elements from other elements, viz.-elements without which a work in any particular art cannot even come into existence » Kandinsky [10, pp20]. Just as a painter manipulates and coordinates colours and a composer combinations of sound, kinetic artists coordinate processes. The computer is a powerful tool for the kinetic artist willing to explore the utility of algorithms represented as program code. Yet the kinds of processes which may be modelled need to be studied, just as a painter studies colour [9] and form [10]. This paper presents such a study of physical processes.