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Quantitative Importance (quantitative + importance)

Distribution by Scientific Domains

Earth and Environmental Science	33%
Business, Economics, Finance and Accounting	33%

Selected Abstracts

In search of stable soil organic carbon fractions: a comparison of methods applied to soils labelled with 14C for 40 days or 40 years

EUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2008
S. Bruun
Summary A reliable method for the isolation of a stable fraction of soil organic carbon (SOC) would be very helpful for improving our understanding of the mechanisms responsible for stabilization of SOC and the dynamics of SOC turnover. We tested acid hydrolysis, physical fractionation (particle density/size), photo-oxidation, treatment with chemical oxidants (NaOCl and NaS2O8) and thermal treatment on two soils incubated with 14C-labelled barley straw for either 40 days or 40 years. Different intensities of the treatments were included. Acid hydrolysis, photo-oxidation and treatment with a chemical oxidant consistently removed more 40-year-old C than 40-day-old C, which suggests that the isolated fractions contained a large proportion of material with a relatively rapid turnover. The clay + silt associated SOC fraction contained a small proportion of 40-day-old C and a large proportion of 40-year-old C. This is consistent with a SOC fraction with medium turnover. The thermal treatment removed more 40-year-old C than 40-day-old C. At 400°C there was still a small proportion of the 40-year-old C remaining, whereas almost all the 40-day-old C was removed. This is consistent with a stable SOC fraction. However, because only 2,3% of the C remained after this treatment, the isolated SOC fraction may be of little quantitative importance. Furthermore, the thermally resistant fraction is likely to be heavily altered by the treatment, and therefore unsuitable for further studies of the chemical nature of stable SOC. [source]

Unemployment, Government Spending and the Laffer Effect,

FISCAL STUDIES, Issue 2 2010
Ludger Linnemann
E62 Abstract The paper studies the effects of income tax rate changes in a general equilibrium model with frictional unemployment. Laffer curve effects, by which a tax rate reduction may increase the level of government spending or its share in output, are shown to be possible under certain conditions. These are the presence of unemployment benefit payments, government budget balance through fiscal spending adjustment and limited quantitative importance of labour reallocation costs. Endogenous government spending acts as a fiscal accelerator if the fiscal burden of unemployment benefit payments is large, but reduces the employment effects of tax rate cuts if it is low. [source]

Impact of past and present land-management on the C-balance of a grassland in the Swiss Alps

GLOBAL CHANGE BIOLOGY, Issue 11 2008
NELE ROGIERS
Abstract Grasslands cover about 40% of the ice-free global terrestrial surface, but their quantitative importance in global carbon exchange with the atmosphere is still highly uncertain, and thus their potential for carbon sequestration remains speculative. Here, we report on CO2 exchange of an extensively used mountain hay meadow and pasture in the Swiss pre-Alps on high-organic soils (7,45% C by mass) over a 3-year period (18 May 2002,20 September 2005), including the European summer 2003 heat-wave period. During all 3 years, the ecosystem was a net source of CO2 (116,256 g C m,2 yr,1). Harvests and grazing cows (mostly via C export in milk) further increased these C losses, which were estimated at 355 g C m,2 yr,1 during 2003 (95% confidence interval 257,454 g C m,2 yr,1). Although annual carbon losses varied considerably among years, the CO2 budget during summer 2003 was not very different from the other two summers. However, and much more importantly, the winter that followed the warm summer of 2003 observed a significantly higher carbon loss when there was snow (133±6 g C m,2) than under comparable conditions during the other two winters (73±5 and 70±4 g C m,2, respectively). The continued annual C losses can most likely be attributed to the long-term effects of drainage and peat exploitation that began 119 years ago, with the last significant drainage activities during the Second World War around 1940. The most realistic estimate based on depth profiles of ash content after combustion suggests that there is an 500,910 g C m,2 yr,1 loss associated with the decomposition of organic matter. Our results clearly suggest that putting efforts into preserving still existing carbon stocks may be more successful than attempts to increase sequestration rates in such high-organic mountain grassland soils. [source]

On weighted P-quantile aggregation

INTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 3 2008
Jongyun Hao
We consider the problem of aggregating ordinal information with quantitative or qualitative importance based on quantile operations. For a bag ,x1, x2, ,, xn, in real or in (finite) ordinal scales, the quantile operations used in this paper are operating based on the floating position index of xi that is determined by its position on the ordered sequence (x(1), x(2), ,, x(n)), where x(i) is the ith smallest element of the bag ,x1, x2, ,, xn,. We call this type of quantile aggregation as the floating position index-based quantile (p-quantile) aggregation. We study on weighted p-quantile aggregation in real scales and extend the corresponding techniques to p-quantile aggregation of ordinal information with quantitative importance. The aggregated result of the latter is represented by a general ordinal proportional 2-tuple. On basis of the notion of importance transformation (that is modified from Yager), we investigate p-quantile aggregation of ordinal information with qualitative importance. Then, we use p-quantile aggregation to define the floating position index-based ordered weighted averaging (P-OWA) aggregation of ordinal information with qualitative importance and apply it to the problem of multicriteria decision making. © 2008 Wiley Periodicals, Inc. [source]

The Principal Components of Growth in the Less Developed Countries

KYKLOS INTERNATIONAL REVIEW OF SOCIAL SCIENCES, Issue 4 2008
Derek Headey
SUMMMARY This paper re-examines the international evidence on the sources of growth in less developed countries (LDCs) using exploratory factor analysis (EFA). Although EFA was first used in the development context by Adelman and Morris (1967) it has rarely been used since, despite being ideally suited to a context in which a large number of latent factors have been hypothesized to determine growth, and in which an even greater number of imperfectly measured and multicollinear proxies have been used to measure these latent factors. This paper uses EFA to minimize these problems of omitted variables biases, multicollinearity and measurement error, by reducing a large array of hypothesized growth determinants into a parsimonious and non-collinear set of composite indices. The paper then provides theoretical interpretations of the derived indices, tests their statistical significance and quantitative importance in otherwise conventional growth regressions, and uses these results to reappraise the usefulness of cross-country empirics in deriving robust, policy-relevant knowledge of the principal components of growth in LDCs, including the so called ,economic miracles'. [source]

The relationship between soil seed bank, above-ground vegetation and disturbance intensity on old-field successional permanent plots

APPLIED VEGETATION SCIENCE, Issue 4 2009
Michaela Dölle
Abstract Questions: How does disturbance and successional age influence richness, size and composition of the soil seed bank? What is the potential contribution of the soil seed bank to the plant community composition on sites differing in their successional age or disturbance intensity? Location: Experimental Botanical Garden of Göttingen University, central Germany. Methods: Above-ground vegetation and soil seed bank were studied on formerly arable fields in a 36-year-old permanent plot study with five disturbance intensities, ranging from yearly ploughing via mowing to long-term uninterrupted succession. We compared species compositions, seed densities and functional features of the seed bank and above-ground vegetation by using several methods in parallel. Results: The seed bank was mainly composed of early successional species typical of strongly disturbed habitats. The difference between seed bank composition and above-ground vegetation decreased with increasing disturbance intensity. The species of greatest quantitative importance in the seed bank was the non-native forb Solidago canadensis. Conclusions: The ability of a plant community to regenerate from the soil seed bank dramatically decreases with increasing time since abandonment (successional age) and with decreasing disturbance intensity. The present study underlines that plant species typical of grasslands and woodlands are limited by dispersal capacity, owing to low capacity for accumulation of seeds in the soil and the fact that most species do not build up persistent seed banks. Rare and target species were almost absent from the seed bank and will, after local elimination, depend on reintroduction for continuation of their presence. [source]