bluuebunny/crossref_metadata_2025_split huggingface dataset:
Publicly‐funded UK agricultural R&D and ‘social’ total factor productivity
Authors: Barnes Andrew P. 
Published: August 2005

AbstractMost studies concerned with measuring the rate of return to publicly‐funded agricultural R&D investment have found high returns, suggesting under‐investment, and calls for increased expenditure have been common. However, the evaluation of returns tends to measure the effect of research expenditure against growth in total factor productivity (TFP), based on market inputs and outputs. When compared against growing public unease over the environmental effects of pursuing agricultural productivity growth, TFP indices become a misleading measure of growth. This paper integrates some non‐market components into the TFP index. The costs of two specific externalities of agricultural production, namely fertiliser and pesticide pollution, are integrated in a TFP index constructed for the period 1948–1995. This adjusted, or ‘social’, TFP index is measured against UK public R&D expenditures.The rates of return to agricultural R&D are reduced by using the ‘social’ as opposed to the traditional TFP index. Whilst both remain at justifiable levels, previous studies appear to have over‐estimated the effect of agricultural R&D expenditures. Furthermore, with changes in policy towards more socially acceptable but non‐productivity enhancing outcomes, such as animal welfare, rural diversification and organic farming, the future framework for analysing returns to agricultural R&D should not be so dependent on productivity growth as an indicator of research effectiveness.
Are commodity prices chaotic?
Authors: Chatrath Arjun , Adrangi Bahram , Dhanda Kanwalroop Kathy 
Published: August 2005

AbstractWe conduct tests for the presence of low‐dimensional chaotic structure in the futures prices of four important agricultural commodities. Though there is strong evidence of non‐linear dependence, the evidence suggests that there is no long‐lasting chaotic structure. The dimension estimates for the commodity futures series are generally much higher than would be for low dimension chaotic series. Our test results indicate that autoregressive conditional heteroskedasticity (ARCH)‐type processes, with controls for seasonality and contract‐maturity effects, explain much of the non‐linearity in the data. We make a case that employing seasonally adjusted price series is important in obtaining robust results via some of the existing tests for chaotic structure. Finally, maximum likelihood methodologies, that are robust to the non‐linear dynamics, lend strong support to the Samuelson hypothesis of maturity effects in futures price changes.
Under the hood Issues in the specification and interpretation of spatial regression models
Authors: Anselin Luc 
Published: August 2005

AbstractThis paper reviews a number of conceptual issues pertaining to the implementation of an explicit “spatial” perspective in applied econometrics. It provides an overview of the motivation for including spatial effects in regression models, both from a theory‐driven as well as from a data‐driven perspective. Considerable attention is paid to the inferential framework necessary to carry out estimation and testing and the different assumptions, constraints and implications embedded in the various specifications available in the literature. The review combines insights from the traditional spatial econometrics literature as well as from geostatistics, biostatistics and medical image analysis.
Location and uptake: integrated household and GIS analysis of technology adoption and land use, with application to smallholder dairy farms in Kenya
Authors: Staal S.J. , Baltenweck I. , Waithaka M.M. , DeWolff T. , Njoroge L. 
Published: August 2005

AbstractCIS‐derived measures of location and space have increasingly been used in models of land use and ecology. However, they have made few inroads into the literature on technology adoption in developing countries, which continues to rely mainly on survey‐derived information. Location, with all its dimensions of market access, demographics and agro‐climate, nevertheless remains key to understanding potential for technology use. The measures of location typically used in the adoption literature, such as locational dummy variables that proxy a range of locational factors, now appear relatively crude given the increased availability of more explicit GIs‐derived measures. This paper attempts to demonstrate the usefulness of integrating CIS‐measures into analysis of technology uptake, for better differentiating and understanding locational effects. A set of GIs‐derived measures of market access and agro‐climate are included in a standard household model of technology uptake, applied to smallholder dairy farms in Kenya, using a sample of 3330 geo‐referenced farm households. The three technologies examined are keeping of dairy cattle, planting of specialised fodder, and use of concentrate feed. Logit estimations are conducted that significantly differentiate effects of individual household characteristics from those related to location. The predicted values of the locational variables are then used to make spatial predictions of technology potential. Comparisons are made with estimations based only on survey data, which demonstrate that while overall explanatory power may not improve with CIS‐derived variables, the latter yield more practical interpretations, which is further demonstrated through predictions of technology uptake change with a shift in infrastructure policy. Although requiring large geo‐referenced data sets and high resolution GIS layers, the methodology demonstrates the potential to better unravel the multiple effects of location on farmer decisions on technology and land use.
Land use dynamics in the central highlands of Vietnam: a spatial model combining village survey data with satellite imagery interpretation
Authors: Muller Daniel , Zeller Manfred 
Published: August 2005

AbstractThe paper investigates geo‐physical, agro‐ecological, and socio‐economic determinants of past land use change in two districts of Dak Lak province in the Central Highlands of Vietnam and assesses the influence of rural development policies on land cover change. Landsat satellite images from the years 1975, 1992 and 2000 are interpreted to detect land cover in two time periods. A survey in randomly selected villages provides primary recall data on socio‐economic and policy variables hypothesised to influence land use change. Secondary data on rainfall, soil suitability, and topography was obtained from meteorological stations and from a digital soil map and digital elevation model. All data were spatially referenced using geographic information systems (GIS) software. A reduced‐form, multinomial logit model is used to estimate the influence of hypothesised determinants on land use and the probabilities that a certain pixel has one of five land classes during either of the two periods.Results suggest that the first period from 1975 to 1992 was characterised by land‐intensive agricultural expansion and the conversion of forest into grass and agricultural land. During the second period, since 1992, the rapid, more labour‐ and capital‐intensive growth in the agricultural sector was enabled by the introduction of fertiliser, improved access to rural roads and markets, and expansion of the irrigated area. These policies, combined with the introduction of protected forest areas and policies discouraging shifting cultivation during the second period reduced the pressure on forests while at the same time increasing agricultural productivity and incomes for a growing population. Forest cover during the second period mainly increased due to the regeneration of areas formerly used for shifting cultivation.
Apoptosis in the epithelial cells of the rests of Malassez of the periodontium of rat molars
Authors: Cerri P. S. , Katchburian E. 
Published: August 2005

Background and objectives:  Epithelial rests of Malassez are clusters of cells derived from Hertwig's root sheath that remain in the periodontal ligament throughout life. Although it is known that the cells of Malassez proliferate, there are no studies showing that they undergo programmed cell death, i.e. apoptosis. In most tissues, proliferation is balanced by apoptosis. Thus we examined regions of the periodontium of young and adult rat molars in the hope of detecting apoptosis.Methods:  Wistar rats aged 29, 45 and 120 days were killed with chloral hydrate (600 mg/kg). Fragments containing maxillary molars were removed and fixed in formaldehyde, decalcified, and embedded in paraffin and glycol methacrylate. Sections were stained with hematoxylin/eosin and the Terminal deoxynucleotidyl transferase‐mediated dUTP Nick End Labeling (TUNEL) method for detection of apoptosis. Specimens were also fixed in glutaraldehyde‐formaldehyde, decalcified and processed for transmission electron microscopy.Results:  Epithelial rests of Malassez containing round/ovoid basophilic dense bodies and TUNEL‐positive structures were found in all specimens examined. Ultrastructural examination revealed that some cells of Malassez contained masses of condensed peripheral chromatin and a shrunken cytoplasm exhibiting intact organelles – images typical of apoptosis. Moreover, round/ovoid electron‐opaque structures appeared to be in the process of being engulfed by neighboring epithelial cells of Malassez.Conclusions:  Our results demonstrate that epithelial cells of Malassez's rests undergo apoptosis in the developing and adult periodontium. Apoptosis may, together with proliferation, be part of the mechanism of turnover/remodelling of the cells of Malassez.
A synergistic chlorhexidine/chitosan combination for improved antiplaque strategies
Authors: Decker E.‐M. , Von Ohle C. , Weiger R. , Wiech I. , Brecx M. 
Published: August 2005

Background:  The minor efficacy of chlorhexidine (CHX) on other cariogenic bacteria than mutans streptococci such as Streptococcus sanguinis may contribute to uneffective antiplaque strategies.Methods and Results:  In addition to CHX (0.1%) as positive control and saline as negative control, two chitosan derivatives (0.2%) and their CHX combinations were applied to planktonic and attached sanguinis streptococci for 2 min. In a preclinical biofilm model, the bacteria suspended in human sterile saliva were allowed to attach to human enamel slides for 60 min under flow conditions mimicking human salivation. The efficacy of the test agents on streptococci was screened by the following parameters: vitality status, colony‐forming units (CFU)/ml and cell density on enamel. The first combination reduced the bacterial vitality to ∼0% and yielded a strong CFU reduction of 2–3 log10 units, much stronger than CHX alone. Furthermore, the first chitosan derivative showed a significant decrease of the surface coverage with these treated streptococci after attachment to enamel.Conclusions:  Based on these results, a new CHX formulation would be beneficial unifying the bioadhesive properties of chitosan with the antibacterial activity of CHX synergistically resulting in a superior antiplaque effect than CHX alone.
Barriers to provision of dental care in long‐term care facilities: the confrontation with ageing and death
Authors: Nitschke Ina , Ilgner Alexander , Müller Frauke 
Published: August 2005

Objective:  The aim of the study was to reveal barriers to providing dental care for residents in long‐term care (LTC) facilities.Design:  Participants were selected randomly from the dentist register in Berlin and Saxony, Germany. The sample consisted of 60 self‐employed and 60 employed dentists, a further 60 dentists worked in their own dental practice but also part‐time in an LTC facility. In semi‐structured interviews a questionnaire with 36 statements concerning working conditions, administration and cost, insecurity concerning treatment decisions as well as confrontation with ageing and death was employed. Subsequently, the study participants were asked to rank the four dimensions concerning their impact on the decision against providing dental care in an LTC facility.Results:  The random sample was representative in age and gender for the dental register in Berlin and Saxony. Fifty‐six per cent of the participants (63% of the men and 51% of the women; 52% of the self‐employed, 60% of the employed and 56% of the consultant dentists) indicated unfavourable working conditions as biggest obstacle in providing dental care in an LTC‐facility. Thirty‐two per cent of participants rated administration and cost, 7% the insecurity in treatment decisions as major hindrance. Only 5% of the participants rated the confrontation with age and death as substantial barrier. There were no age and gender differences. Dentists in Berlin seemed more concerned about administration and cost of a consultancy activity and less secure in their therapy decisions than the colleagues from Saxony (p < 0.001). Dentists who work partly in LTC facilities were the least concerned about the confrontation with ageing and death (not significant), employed dentist showed the least secure in their treatment decisions (p > 0.001).Conclusion:  It can be concluded that the awareness of infra‐structural and financial aspects in providing dental care in LTC facilities should be raised with health politicians and that these aspects should be considered when inaugurating or re‐structuring the consultancy services to LTC facilities. Further it would be desirable to establish more postgraduate training programmes to increase clinical and ethical competence in the area of gerodontology.
On the Shape–Slope Relation of Drop Size Distributions in Convective Rain
Authors: Seifert Axel 
Published: August 2005

Abstract
The relation between the slope and shape parameters of the raindrop size distribution parameterized by a gamma distribution is examined. The comparison of results of a simple rain shaft model with an empirical relation based on disdrometer measurements at the surface shows very good agreement, but a more detailed discussion reveals some difficulties—for example, deviations from the gamma shape and the overestimation of collisional breakup.
Hydrometeor Retrieval Accuracy Using Microwave Window and Sounding Channel Observations
Authors: Bauer Peter , Moreau Emmanuel , Di Michele Sabatino 
Published: August 2005

Abstract
The retrieval errors of cloud and precipitation hydrometeor contents from spaceborne observations are estimated at microwave frequencies in atmospheric windows between 18 and 150 GHz and in oxygen absorption complexes near 50–60 and 118 GHz. The method is based on a variational retrieval framework using a priori information on the cloud, atmosphere, and surface states from ECMWF short-range forecasts under different weather regimes. This approach was chosen because a consistent description of the model state and its uncertainties is provided, which is unavailable for other methods. The results show that the sounding channels provide more stable, more accurate, and less biased retrievals than window channels—in particular, over land surfaces and with regard to snowfall. Average performance estimates showed that if sounding channels are used, 80% of all retrievals are within 100% error limits and 60% of them are within 50% error limits with regard to rainfall. For snowfall, the sounding channels produce 60% of all retrievals with errors below 100% for rates smaller than 1 mm h−1, and 50%–80% of the cases have errors below 50% for more intense snowfall.
Application of a Multigrid Method to a Mass-Consistent Diagnostic Wind Model
Authors: Wang Yansen , Williamson Chatt , Garvey Dennis , Chang Sam , Cogan James 
Published: August 2005

Abstract
A multigrid numerical method has been applied to a three-dimensional, high-resolution diagnostic model for flow over complex terrain using a mass-consistent approach. The theoretical background for the model is based on a variational analysis using mass conservation as a constraint. The model was designed for diagnostic wind simulation at the microscale in complex terrain and in urban areas. The numerical implementation takes advantage of a multigrid method that greatly improves the computation speed. Three preliminary test cases for the model’s numerical efficiency and its accuracy are given. The model results are compared with an analytical solution for flow over a hemisphere. Flow over a bell-shaped hill is computed to demonstrate that the numerical method is applicable in the case of parameterized lee vortices. A simulation of the mean wind field in an urban domain has also been carried out and compared with observational data. The comparison indicated that the multigrid method takes only 3%–5% of the time that is required by the traditional Gauss–Seidel method.
Evolution of a microbial nitrilase gene family: a comparative and environmental genomics study
Authors: Podar Mircea , Eads Jonathan R , Richardson Toby H 
Published: August 2005

Abstract

Background
Completed genomes and environmental genomic sequences are bringing a significant contribution to understanding the evolution of gene families, microbial metabolism and community eco-physiology. Here, we used comparative genomics and phylogenetic analyses in conjunction with enzymatic data to probe the evolution and functions of a microbial nitrilase gene family. Nitrilases are relatively rare in bacterial genomes, their biological function being unclear.

Results
We examined the genetic neighborhood of the different subfamily genes and discovered conserved gene clusters or operons associated with specific nitrilase clades. The inferred evolutionary transitions that separate nitrilases which belong to different gene clusters correlated with changes in their enzymatic properties. We present evidence that Darwinian adaptation acted during one of those transitions and identified sites in the enzyme that may have been under positive selection.

Conclusion
Changes in the observed biochemical properties of the nitrilases associated with the different gene clusters are consistent with a hypothesis that those enzymes have been recruited to a novel metabolic pathway following gene duplication and neofunctionalization. These results demonstrate the benefits of combining environmental genomic sampling and completed genomes data with evolutionary and biochemical analyses in the study of gene families. They also open new directions for studying the functions of nitrilases and the genes they are associated with.
Epidemiologic study of chronic hepatitis B virus infection in male volunteer blood donors in Karachi, Pakistan
Authors: Akhtar Saeed , Younus Muhammad , Adil Salman , Hassan Farrukh , Jafri Sarffraz Hussain 
Published: August 2005

Abstract

Background
The magnitude of chronic infection with hepatitis B virus (HBV) varies substantially between the countries. A better understanding of incidence and/ or prevalence of HBV infection and associated risk factors provides insight into the transmission of this infection in the community. The purpose of this investigation was to estimate the prevalence of and to identify the risk factors associated with chronic infection with HBV, as assessed by HBV surface antigen (HBsAg) positivity, in asymptomatic volunteer male blood donors in Karachi, Pakistan.

Methods
Consecutive blood donations made at the two large blood banks between January 1, 1998 and December 31, 2002 were assessed to estimate the prevalence of HBsAg positivity. To evaluate the potential risk factors, a case-control study design was implemented; cases (HBsAg positives) and controls (HBsAg negatives), were recruited between October 15, 2001 and March 15, 2002. A pre-tested structured questionnaire was administered through trained interviewers to collect the data on hypothesized risk factors for HBV infection. Sera were tested for HBsAg using commercially available kits for enzyme linked Immunosorbant assay-III.

Results
HBsAg prevalence in the male volunteer blood donors was 2.0 % (7048/351309). Multivariate logistic regression analysis showed that after adjusting for age and ethnicity, cases were significantly more likely than controls to have received dental treatment from un-qualified dental care provider (adjusted odds ratio (OR) = 9.8; 95% confidence interval (CI): 2.1, 46.1), have received 1–5 injections (adjusted OR = 3.3; 95% CI: 1.1, 9.6), more than 5 injections (adjusted OR = 1.4; 95% CI: 1.4, 12.7) during the last five years or have received injection through a glass syringe (adjusted OR = 9.4; 95% CI: 2.6, 34.3). Injury resulted in bleeding during shaving from barbers (adjusted OR = 2.3; 95% CI: 1.1, 4.8) was also significant predictor of HBsAg positivity.

Conclusion
Prevalence of HBsAg positivity in the male volunteer blood donors in Karachi was 2%. Infection control measures in health-care settings including safe injection practices and proper sterilization techniques of medical instruments and education of barbers about the significance of sterilization of their instruments may reduce the burden of HBV infection in this and similar settings. There is also an urgent need of developing locally relevant guidelines for counseling and management of HBsAg positive blood donors.
Case-control study on analgesics and nephropathy (SAN): protocol
Authors: Heinemann Lothar AJ , Garbe Edeltraut , Lewis Michael , van der Woude Fokko , Graf Helmut 
Published: August 2005

Abstract

Background
The association between intake of non-phenacetin-containing analgesics and the occurrence of chronic renal failure is still controversially discussed. A new epidemiologic study was planned and conducted in Germany and Austria.

Methods/design
The objective of the international, multicenter case-control study was to evaluate the association between end-stage renal disease (ESRD) and use of non-phenacetin-containing analgesics with particular emphasis on combined formulations. A targeted sample of 1000 new (incident) dialysis patients, aged less than 50 years, was planned to recruit between January 1, 2001 and December 31, 2004. The age limit was chosen to avoid contamination of the study population with phenacetin-containing analgesics to the extent possible. Four control subjects per ESRD case, matched by age, sex, and region were selected from the population living in the region the case came from.
Lifetime exposure to analgesics and potential renal risk factors were recorded in a single face-to-face interview. A set of aids was introduced to reinforce the memory of study participants.
A standardized, pre-tested interview questionnaire (participants), a medical documentation sheet (physicians in dialysis centres), a logbook for all activities (dialysis centres) were used to collect the necessary data.
Quality management consisted of the standardized procedures, (re-) training and supervision of interviewers, regular checks of all incoming data for completeness and plausibility.
The study is scientifically independent and governed by a international Scientific Advisory Committee that bridged the gap between the sponsoring companies and the investigators. Also other advisory groups assisted the managing committee of the study. All relevant German and Austrian nephrological associations supported the study, and the study design was carefully reviewed and approved by the Kidney Foundation of Germany.

Discussion
The study is expected to answer the main research question by end 2005. There is however a high potential for various biases that we tried to address with adequate measure. One limitation however cannot be overcome: The methodologically needed age-limitation of the study will make it not easy to generalize the results to age groups over 50 years. It might be suggested to repeat the study for persons over 50 years in 10 years when contamination with phenacetin use early in life is likely to be outgrown.