bluuebunny/crossref_metadata_2025_split huggingface dataset:
One‐dimensional image analysis of soil structure. 11. Interpretation of parameters with respect to four forest soil profiles
Authors: RINGROSE‐VOASE A. J. , NYS C. 
Published: August 2010

SUMMARYThe one‐dimensional (1‐D) image analysis system described in the companion to this paper (Part I) was used to analyse horizontal sections of pore space (≥ 180 μm) in four forest soil profiles with impeded drainage. Parameters were interpreted with respect to structure in the images. Mean solid intercept length is inversely proportional to extent of pore space. It was longer for blocky structures than massive structures, which had extensive, fine pore space. It decreased with decreasing ped size, increasing development and increasing intrapedal porosity. The solid intercept length distribution separated the effects of intrapedal porosity. For blocky structures, the pore intercept length distribution indicated the sizes and quantities of fissures and intrapedal pores. All profiles had an horizon with blocky structure with lower porosity owing to greater distance between interpedal pore space and low extent of intrapedal pore space. The deeper, more massive horizons had extensive, fine pore space separating fine aggregates.
A two‐dimensional quantification of soil ped shape
Authors: HOLDEN N. M. 
Published: August 2010

SUMMARYQuantification of soil ped shape is discussed from three viewpoints:

The theoretical reasons why quantification of ped shape should be useful (objective classification of shape, improved understanding of ped/pore relationships, soil genesis and ped development and as a measure of soil heterogeneity);
The theoretical division of irregular shape into three components (circularity, angularity and surface roughness) and how circularity and surface roughness can be quantified using Cox's R‐statistic and the Fractal dimension (D). Angularity remains unquantified;
The testing of a computer program written to quantify ped shape against six criteria that were presented (Clark, 1981) to allow an assessment of shape quantification methods and the calibration of the program using Pettijohn's (1 957) standard shape chart.

It is concluded that R and D are able quantifiers of irregular particle shape.
An energy based parameter for the assessment of aggregate bond energy
Authors: RAINE S. R. , SO H. B. 
Published: August 2010

SUMMARYThe energy applied to a soil‐water suspension by an ultrasonic probe was determined for seven vertisol soils using calorimetric techniques. The rate of energy consumed by aggregate dispersion during sonification was calculated as the difference between the energy components measured before and after complete dispersion. Dispersive energy consumption was found to vary significantly during sonification and significant differences (P<0.05) were found between soils for the total dispersive energy required for complete dispersion. The soil dispersion characteristic curves, which relate the dispersive energy consumption during sonification to the quantity of <2 μm and <20 μm material dispersed, were also significantly different between soils. Error analysis of the calorimetric technique revealed that the energy consumed by complete dispersion is calculated with a precision of ±0.5 J g−1. For the soils studied, this was smaller than the observed variance in total dispersive energy consumed suggesting sample variability was the major source of variation.The ultrasonic technique was also used to determine the equivalent total energy applied and the amount of energy consumed by aggregate breakdown and dispersion during 30 min of end‐over‐end shaking. No significant difference (P<0.05) was found between soils for the total energy applied. However, a significant difference (P<0.05) was observed between soils for the quantity of dispersive energy required to produce the equivalent end‐over‐end dispersion.
Effect of sample pretreatment on aggregate stability measured by wet sieving or turbidimetry on soils of different cropping history
Authors: HAYNES R. J. 
Published: August 2010

SUMMARYThe effects of cropping history (pasture or arable) and sample pretreatment (field‐moist, air‐dried or air‐dried and then tension or vacuum rewetted) on aggregate stability as measured by wet sieving or turbidimetry were compared. When field‐moist samples were used there was a tendency for aggregate stability, as measured by wet sieving, to decline with increasing time under arable cropping (i.e. decreasing soil organic matter content). Air‐drying samples caused a pronounced decline in stability of soils from under arable management and as a consequence there was a marked decline in stability with increasing time under arable. Use of tension or vacuum rewetted samples resulted in high values of stability which were unaffected by cropping history.For turbidimetry, there was a marked decline in measured stability with increasing time under arable cropping when field‐moist samples were used. Air‐drying caused an increase in measured stability that was relatively greater for the less stable samples. In comparison with air‐dried samples, tension and vacuum rewetting caused a decrease in stability values for relatively unstable soils.It is suggested that, upon air‐drying (and contraction of aggregates), additional intermolecular associations were formed between soil constituents thus conferring greater stability on aggregates. This resulted in reduced dispersion (and the release of particles <0.04 mm in diameter) from the surfaces of aggregates and slaked aggregate fragments following rapid rewetting. As a consequence stability as measured by turbidimetry was increased by drying. For aggregates from a predominantly arable history, this stabilization was not great enough to prevent slaking occurring following rapid rewetting, with the formation of a large proportion of stabilized fragments <0.5 mm in diameter. The stability of these aggregates as measured by wet sieving was therefore decreased by drying.
A model for predicting the fate of nitrogen fertilizer in lowland ricefields
Authors: SINGH RACHHPAL , KIRK G. J. D. 
Published: August 2010

SUMMARYEquations are developed for the simultaneous movement and reaction in flooded soils of urea, ammoniacal species, carbonate species, and acids and bases, the simultaneous uptake of N by a developing rice root system, and losses of NH3 and CO2 by volatilization from the floodwater. The equations allow for the initial distribution of urea and other reactants in the soil and floodwater, for movement both by diffusion and convection, and for the rates of urea hydrolysis, floodwater algal activity, organic‐C and ‐N mineralization, and H+ release from roots to balance excess uptake of cations over anions. The equations are combined in a computer model which can predict the fate of N fertilizer in lowland ricefields for any combination of crop and environmental conditions.
K‐fixing phyllosilicates in soils: the role of inherited components
Authors: BÜHMANN C. 
Published: August 2010

SUMMARYK‐fixing potential of 29 illite/smectite mixed‐layer minerals, covering a broad range in layer ratios and stacking arrangements, has been investigated utilizing X‐ray diffraction as the principal investigative tool. Samples were derived from a borehole core transecting Permian sedimentary rocks. In 93% of all samples, K+ was retained against replacement with Mg2+ from a 1 M MgCI2 solution in an average of 33% of the smectitic interlayers, defined via expansion to 1.7 nm upon ethylene glycol solvation after Mg‐saturation. This non‐ideal smectite behaviour points to a vermiculite‐type layer charge. Ordered structures fixed on average 20% more K than did random ones, but results were widely scattered. The Greene‐Kelly test revealed predominantly tetrahedral substitution, intercalation with dodecylammonium chloride molecules a high interlayer charge density in samples with a high K‐fixing capacity.The findings have implications in two fields: in pedology, soils developed from thermally altered sedimentary rocks may inherit a considerable potential for K–fixation; in mineral identification, interlayers in illite/smectite interstratifications fully expanded to 1.7 nm upon ethylene glycol solvation despite their vermiculite–type layer charge. Glycerol solvation provided equally inconsistent results, while dodecylammonium spacings seemed to correlate reasonably well with interlayer charge density characteristics.
Availability to plants of phosphate adsorbed on goethite: experiment and simulation
Authors: GEELHOED J. S. , FINDENEGG G. R. , VAN RIEMSDIJK W. H. 
Published: August 2010

SummaryA model has been developed to predict the availability of sorbed phosphate to plants. It is based on uptake by a growing root system. Phosphate sorption is assumed to be reversible and the rate of desorption is assumed not to limit uptake. The model was tested against observed availability of sorbed phosphate estimated from uptake by plants growing in phosphorus‐deficient conditions. The plants were grown on quartz sand coated with goethite on which phosphate was adsorbed, and which was mixed with nutrient solution. The influence of the phosphate loading of goethite and the goethite content of the sand on available phosphate was examined. Phosphate uptake was predicted well by the model for treatments with high phosphate loading and different goethite content of the sand. However, for a treatment with low phosphate loading, uptake was underestimated by the model. In this treatment the pH of the 'soil’ solution decreased from 5·5 to 4·2 during the experiment. The phosphate concentration in solution increased with a lowering of the pH in this pH range, resulting in increased phosphate uptake.
On the extent to which root properties and transport through the soil limit nitrogen uptake by lowland rice
Authors: KIRK G. J. D. , SOLIVAS J. L. 
Published: August 2010

SummaryMeasurements of N uptake by rice plants growing in a puddled flooded soil and the corresponding changes in soil solution NH: concentrations and the soil NH: diffusion coefficient are used to calculate how far root uptake properties and transport to the roots limit acquisition of N by rice. With root uptake parameters assigned values such that influx was maximal within realistic ranges, the minimum root length densities required to explain uptake were similar to measured root length densities in both N‐fertilized and unfertilized soil. This suggests that most if not all of the root length was active in uptake and that uptake per unit root length was near maximal. A sensitivity analysis showed that the necessary minimum root length is very sensitive to root uptake properties within appropriate ranges. Transport to the roots was mainly by diffusion. Rates of diffusion will generally not limit uptake in well‐puddled soils, but they may greatly limit uptake in puddled soils that have been drained and re‐flooded and in unpuddled flooded soils. Uptake of fertilizer N broadcast into rice field floodwater and absorbed by roots in the floodwater or soil near the floodwater is not likely to be limited by root uptake properties or transport.
Simulation of soil water retention using random fractal networks
Authors: BIRD N. R. A. , DEXTER A. R. 
Published: August 2010

SummaryThe derivation of pore size distributions from the soil water retention characteristic is complicated by the influence of the connectivity of the pore space on drainage. We examine this issue in the context of a random fractal pore network model. A two‐dimensional one‐parameter model simulates the drainage of water from an initially saturated pore network, explicitly accounting for the complex pore interactions which exist over a range of scales within the network. A parameter range is identified over which pore connections significantly hinder the advance of air into the network. The results demonstrate that connectivity between pores in a random structure can affect the drainage to an extent that in general it is not possible to obtain an accurate measure of the pore size distribution from the water retention data. These results, together with findings based on closely related multiscale network models, show that one should use with caution water retention models derived from fractal structures and based solely on pore size distributions.
Scaling of water flow through porous media and soils
Authors: Roth K. 
Published: August 2010

SummaryScaling of fluid flow in general is outlined and contrasted to the scaling of water flow in porous media. It is then applied to deduce Darcy’s law, thereby demonstrating that stationarity of the flow field at the scale of the representative elementary volume (REV) is a critical prerequisite. The focus is on the implications of the requirement of stationarity, or local equilibrium, in particular on the validity of the Richards equation for the description of water movement through soils. Failure to satisfy this essential requirement may occur at the scale of the REV or, particularly in numerical simulations, at the scale of the model discretization. The latter can be alleviated by allocation of more computational resources and by working on a finer‐grained representation. In contrast, the former is fundamental and leads to an irrevocable failure of the Richards equation as is observed with infiltration instabilities that lead to fingered flow.
Natural, human and spatial constraints to expanding populations of otters in the Iberian Peninsula
Authors: Clavero Miguel , Hermoso Virgilio , Brotons Lluís , Delibes Miguel 
Published: August 2010

AbstractAim  To determine the relationships between otter (Lutra lutra) distribution dynamics and environmental and spatial constraints over a 20‐year period.Location  Andalusia, southern Iberian Peninsula.Methods  We synthesized otter distribution data from three otter surveys (1985, 1995 and 2005) using subcatchment areas defined by hydrological barriers. Subcatchments were characterized by two ‘natural’ (climatic and orographic variables) and two ‘human’ (land use and population density) gradients. In addition, we calculated two contagion variables (the distance to previously occupied subcatchments and the percentage of occupied subcatchments within a 50 km buffer) for consecutively surveyed subcatchments.Results  Between 1985 and 2005 the percentage of subcatchments with otters present increased from 42% to 72%. Otters tended to be rare or absent from human‐dominated areas. Anthropogenic gradients were better predictors of otter distribution than natural ones. Human and natural gradients showed strong covariation, but for any value of the natural gradients otters tended to be present in subcatchments with lower human impacts. Colonization of new subcatchments was found to be strongly related to contagion variables and expansion rates were slower than those estimated in other studies. Newly colonized areas tended to be located in areas with intermediate human influence, while repeated absences occurred mainly in areas where human impact was most severe.Main conclusions  Our results suggest that recent otter expansion across Andalusia is a reflection of large‐scale improvement in environmental conditions. Otter populations that survived the period of strong and generalized declines appear to be acting as sources from which neighbouring areas are colonized, probably aided by improved water quality and increases in food availability. However, the further expansion of otters into their full original range is likely to be constrained by human‐impacted landscapes.
Education and Public Policy
Authors: Dutta Jayasri , Sefton James , Weale Martin 
Published: August 2010

AbstractThis article surveys the literature on education as a matter of public policy. We present international comparisons of expenditure on education and then discuss the contribution of education to economic growth, distinguishing between growth accounting and regression approaches, but concluding that the picture is still confused. We assess the risky nature of investment in higher education and also discuss the link between educational experience and social class. We show that this, when studied in aggregate, accounts for less than half of the persistence of earnings between fathers and sons but it nevertheless does a good job of relating fathers’ and sons’ occupations. Finally, we look at the link between education and earnings in the UK. For most subjects, the private return to university education has held at over 15 per cent p.a. despite the introduction of fees. However, some subjects offer a negative return.
The New Economy: Reality and Policy
Authors: Van Reenen John 
Published: August 2010

AbstractThis paper concerns the new economy (alias the knowledge‐based economy). I examine the different meanings attached to the new economy term and the evidence surrounding it, concentrating on the upsurge in US productivity growth between 1995 and 2000. I argue that the reports of the death of the new economy have been greatly exaggerated. There is evidence that information technology has transformed the US economy and is thus likely to have a strong impact on the UK economy in coming years. I discuss how elements of public policy should adapt to these economic changes, both in terms of an overall framework and in applications to specific areas (technology policy, human capital policy, competition policy and industrial policy). The new economy is a place of hope and fear. The hope is that policy activism can cement in potential productivity gains; the fear is that government actions will not mitigate the seemingly ineluctable pressures towards social exclusion.
Funding a PAYG pension system: the case of Italy
Authors: Forni Lorenzo , Giordano Raffaela 
Published: August 2010

AbstractItaly is characterised by a mature pay‐as‐you‐go social security system and by particularly adverse population projections. Given these trends, the social security contribution rate is expected to increase above its current high level. This hinders the development of employer‐provided pension funds and introduces a significant wedge between labour cost and earnings that discourages both labour demand and labour supply. Any proposal to reduce payroll taxes and to reform the system in the direction of partial funding has to cope with the state of Italian public finances. Italy has to comply with the Stability and Growth Pact that imposes constraints on budget deficit and debt trends. Using micro data from the Bank of Italy's Survey of Household Income and Wealth and official population projections, we estimate future employment trends under different demographic and macroeconomic scenarios and compute the cost of the transition. We show that it would be substantially reduced if positive effects on employment were induced by the payroll tax reduction.
The Croatian profit tax: an ACE in practice
Authors: Keen Michael , King John 
Published: August 2010

AbstractThis paper discusses the experience of Croatia in applying, from 1994 to the beginning of 2001, a profit tax that was charged only on equity income in excess of an imputed normal return ‐ and was thus, in essence, an ‘Allowance for Corporate Equity’ (ACE) scheme of the kind advocated by the IFS Capital Taxes Group and others. The computation of taxable profit under this system is summarised, and the theoretical attractions of the system are described. The paper then discusses a variety of criticisms that were made of the system in Croatia, including an alleged bias in favour of capital‐intensive enterprises (and, in particular, large State‐owned enterprises with overvalued assets), international complications, the complexity of the computations of taxable profit, the possibility that the rate of protective interest was set at an inappropriate level, and excessive revenue cost.
The restructuring and privatisation of British Rail: was it really that bad?
Authors: Pollitt Michael G. , Smith Andrew S. J. 
Published: August 2010

AbstractThis paper uses a social cost‐benefit analysis (SCBA) framework to assess whether rail privatisation in Britain has produced savings in operating costs. The paper shows that major efficiencies have been achieved and consumers have benefited through lower prices, whilst the increased government subsidy has been largely recouped through privatisation proceeds. We also find that output quality is no lower (and is probably better) than under the counterfactual scenario of public ownership (pre‐Hatfield). The achievement of further savings is key to delivering improved rail services in the future. This paper finds that a privatised structure, where shareholders demand a return on their investment, has led to significant improvements in operating efficiency. It remains to be seen whether the new regime, with a not‐for‐profit infrastructure owner, will deliver the same efficiency improvements.
Citizenship and Social Security
Authors: Plant Raymond 
Published: August 2010

AbstractThe aim of this paper is to elucidate the idea of citizenship that lies behind the Labour government's welfare reforms. There has been no proper statement about this from the government, so the paper is an attempt to make explicit what is latent in the reforms. It does this partly historically by looking at ideas of citizenship that have been presupposed in the development of the British Welfare State. It is claimed that there are two rather different approaches to be discerned: one sees citizenship as a basic status, which in turn is the basis of entitlement; the other view is that citizenship is something that has to be developed or achieved, typically by participation in the labour market and by discharging obligations. This distinction is then used more analytically to assess some of the welfare reforms and to indicate possible sources of future difficulty and tension in so far as the government embraces the obligation‐oriented view of citizenship.
Balancing Access to Health Data and Privacy: A Review of the Issues and Approaches for the Future
Authors: Lane Julia , Schur Claudia 
Published: August 2010

Background. There has been a dramatic increase in the types of microdata, and this holds great promise for health services research. However, legislative efforts to protect individual privacy have reduced the flow of health care data for research purposes and increased costs and delays, affecting the quality of analysis.Aim. This paper provides an overview of the challenges raised by concerns about data confidentiality in the context of health services research, the current methodologies used to ensure data security, and a description of one successful approach to balancing access and privacy.Materials and Methods. We analyze the issues of access and privacy using a conceptual framework based on balancing the risk of reidentification with the utility associated with data analysis. The guiding principle should be to generate released data that are as close to the maximum acceptable risk as possible. HIPAA and other privacy measures can perhaps be seen as having had the effect of lowering the “maximum acceptable risk” level and rendering some data unreleasable.Results. We discuss the levels of risk and utility associated with different types of data used in health services research and the ability to link data from multiple sources as well as current models of data sharing and their limitations.Discussion. One particularly compelling approach is to establish a remote access “data enclave,” where statistical protections are applied to the data, technical protections ensure compliance with data‐sharing requirements, and operational controls limit researchers' access to the data they need for their specific research questions.Conclusion. We recommend reducing delays in access to data for research, increasing the use of remote access data enclaves, and disseminating knowledge and promulgating standards for best practices related to data protection.