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Aggregate Resource (aggregate + resource)

Distribution by Scientific Domains

Earth and Environmental Science	50%
Business, Economics, Finance and Accounting	50%

Selected Abstracts

Aggregate sources and supplies in Jamaica

GEOLOGICAL JOURNAL, Issue 5 2008
Peter W. Scott
Abstract Aggregate resources in Jamaica are sand and gravel found in active river systems, and limestone. Other rocks in Cretaceous inliers and elsewhere are generally too weathered at the surface or too remote from centres of population to be considered suitable as significant sources of aggregates. Sand and gravel generally supplies the south of the country with limestone production and markets being concentrated along the northern coastal areas. Limestone aggregates are produced by ripping and crushing, blasting being uncommon. Sand and gravel are often simply processed using a single screen, although fixed crushing and screening plant are used in some operations. The aggregate industry operates inefficiently, generally utilizing old plant, although an economic assessment shows it to be very profitable. Substitution of sand and gravel by limestone would help mitigate the negative environmental impact of extraction of aggregates from active river systems, but would considerably distort the supply of aggregates throughout the country. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Mapping the archaeological soil archive of sand and gravel mineral reserves in Britain

GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 1 2009
Ingrid Ward
Primary sand and gravel deposits in Britain play an important role in preserving our cultural heritage and are also a valuable aggregate resource. While an understanding of the extrinsic properties of the soil archive (such as pH, redox, groundwater) can provide a firstorder assessment of the potential risk to any archaeologically sensitive deposits, we have very poor definition of spatial variations in the extrinsic properties of soil that influence archaeological preservation at a regional and national scale. Developments in digital geological mapping, remote sensing, and geochemical survey data undertaken by the British Geological Survey (BGS) have, however, significantly extended capabilities in this respect and can potentially be used to provide a primary assessment of the sensitivity of the present soil archive and the potential risk from changes to the soil process on cultural material in areas earmarked for aggregate extraction. Two of the major factors affecting archaeological preservation,soil acidification and groundwater,can be mapped or predicted at scales of better than 1:50,000 across increasingly large parts of the country using a combination of regional hydrogeological, geophysical, and geochemical data. Additional data from site investigations may further refine preservation potential as a function of changes in redox potential and acidity. These data, maps and models can be used to (1) better establish a baseline for archaeological preservation at a regional and national scale and (2) improve our understanding of how the physical and chemical properties of the near surface environment can be managed to sustainably preserve archaeological materials in areas impacted by sand and gravel extraction. © 2009 Wiley Periodicals, Inc. [source]

Understanding fire fighting in new product development,

THE JOURNAL OF PRODUCT INNOVATION MANAGEMENT, Issue 5 2001
Nelson P. Repenning
Despite documented benefits, the processes described in the new product development literature often prove difficult to follow in practice. A principal source of such difficulties is the phenomenon of fire fighting-the unplanned allocation of resources to fix problems discovered late in a product's development cycle. While it has been widely criticized, fire fighting is a common occurrence in many product development organizations. To understand both its existence and persistence, in this article I develop a formal model of fire fighting in a multiproject development environment. The major contributions of this analysis are to suggest that: (1) fire fighting can be a self-reinforeing phenomenon; and (2) multiproject development systems are far more susceptible to this dynamic than is currently appreciated. These insights suggest that many of the current methods for aggregate resource and product portfolio planning, while necessary, are not sufficient to prevent fire fighting and the consequent low performance. [source]

Tax and Education Policy in a Heterogeneous-Agent Economy: What Levels of Redistribution Maximize Growth and Efficiency?

ECONOMETRICA, Issue 2 2002
Roland Bénabou
This paper studies the effects of progressive income taxes and education finance in a dynamic heterogeneous-agent economy. Such redistributive policies entail distortions to labor supply and savings, but also serve as partial substitutes for missing credit and insurance markets. The resulting tradeoffs for growth and efficiency are explored, both theoretically and quantitatively, in a model that yields complete analytical solutions. Progressive education finance always leads to higher income growth than taxes and transfers, but at the cost of lower insurance. Overall efficiency is assessed using a new measure that properly reflects aggregate resources and idiosyncratic risks but, unlike a standard social welfare function, does not reward equality per se. Simulations using empirical parameter estimates show that the efficiency costs and benefits of redistribution are generally of the same order of magnitude, resulting in plausible values for the optimal rates. Aggregate income and aggregate welfare provide only crude lower and upper bounds around the true efficiency tradeoff. [source]