bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bank profile and structure as determinants of macroinvertebrate assemblages—seasonal changes and management
Authors: Armitage P.D. , Lattmann K. , Kneebone N. , Harris I. 
Published: January 2005

AbstractManagement and restoration procedures in rivers frequently have a major influence on the bank and marginal zone, depending on the timing of disturbance and the eventual structure of the bank. This study examines changes in macroinvertebrate communities in four different bank types at 3‐weekly intervals throughout a year. The banks differed in their profile and in their structure: shallow sloping and vegetated, stepped shallow profile, steep profile (eroded soil bank), and iron revetments. Velocity patterns over the year showed much variability, both between and within bank types ranging from standing water in the summer to velocities in excess of 0.9 m s−1 in the winter. The shallow‐sloping vegetated site supported a total of 115 taxa, in contrast to the artificial iron revetment, on which only 32 taxa were recorded. Total abundances were five to six times greater in the shallow vegetated sites compared with the steeply sloped and artificial banks. Highest abundances were recorded in the late spring (May/June) and most taxa were found in August and September. Fluctuations in both abundance and number of taxa were least on the reveted bank. Ordination of the fauna/site matrix revealed a seasonal separation with specific winter and summer communities. The results suggest that the bankside is a dynamic environment where communities change in relation to growth of bankside vegetation and its concomitant effect on flow. The implications of these findings to management activities and restoration procedures are discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Hydromorphological control of phosphorus in a large free‐flowing gravel bed river: the Garonne River (France)
Authors: Bonvallet Garay S. , Sauvage S. , Vervier P. 
Published: January 2005

AbstractThe objective of this paper is to relate phosphorus (P) transport dynamics and hydromorphological characteristics of a large human‐influenced river, the River Garonne within a sector receiving the waste water of a sewage treatment plant for a population of 600 000. Two studies were conducted in 1997 and 1999 during two different hydrological conditions at low‐flow periods. The 1997 study was carried out on an 18‐km stretch with discharges varying between 33 and 53 m3/s and with very small fluctuations. The 1999 study concerned a longer stretch of 47 km, divided into four smaller reaches, and with discharges fluctuating rapidly from 40 to 108 m3/s.Downstream of the sewage treatment plant, total phosphorus (TP) concentrations ranged from 0.19 to 0.27 mg/L and were mainly in the dissolved form: between 60 and 78% of TP was dissolved reactive phosphorus (DRP). P concentrations were significantly lower upstream of the sewage treatment plant.By a mass‐balance approach, we estimated that the sewage treatment plant represents more than half the input (between 59 and 67%) of the studied sector. TP dynamic is linked to suspended solids for discharges above 60 m3/s.During established low‐flow period in the 1997 study (<60 m3/s), 22 and 27% of TP and DRP were retained by the river bed.In the 1999 study, under different low‐water period hydraulic conditions, we calculate that particulate P retention occurred in two reaches among the four under study and only for discharges below 60 m3/s.We show that for established discharges below 60 m3/s, there is an active uptake of transported P by functional compartments (i.e. the hyporheic zone and the periphyton). During the low‐water period with relatively high hydraulic fluctuations, and for discharges >60 m3/s, P retention is controlled as expected by suspended matter dynamics.We conclude that management of the hydrological regime can influence P retention during sensitive low‐water periods. Copyright © 2001 John Wiley & Sons, Ltd.
Reallocation of compensation releases to restore river flows and improve instream habitat availability in the Upper Derwent Catchment, Derbyshire, UK
Authors: Maddock I.P. , Bickerton M.A. , Spence R. , Pickering T. 
Published: January 2005

AbstractThe Upper Derwent catchment is situated in the Peak District National Park in North Derbyshire, England and includes the Derwent Valley Reservoir System. The natural inflows to the reservoir system are boosted by flow diversion schemes from the River Ashop and River Noe, leaving almost dry stretches in these rivers for long periods of time. Compensation releases are made into Jaggers Clough and the River Derwent. This study examined the possibility of altering the operation of the diversion scheme and compensation flow releases, both temporally and spatially to restore flows within these dry reaches. The overall intention was to minimize the ecological impacts of regulation in the four rivers whilst protecting the yield of this critical public water supply.The study utilized the Physical Habitat Simulation System (PHABSIM) to identify and compare feasible operational changes. This technique enables quantitative comparisons of the suitable habitat available under different flow regime scenarios.Brown Trout is the most abundant fish species in the Upper Derwent streams, with Grayling, Brook Lamprey and Bullhead also present. The invertebrate fauna is typical of upland streams with neutral to acid waters. The ecological data were assessed to identify suitable target species/life stages for use with PHABSIM. Brown Trout, Grayling and four invertebrate families (Rhyacophilidae, Leuctridae, Chloroperlidae and Heptageniidae) were selected.Habitat mapping along four stretches of river totalling 10 km was carried out in the summer of 1998, followed by PHABSIM fieldwork on 24 transects in the autumn. This information was utilized to examine the tradeoffs in habitat availability between reinstating flows in the dry stretches of river, and reducing compensation flows elsewhere to minimize the supply impact. Various operating scenarios were examined and two sets of compensation control rules proposed for normal and drought years. Each set included seasonal variability in the rules.The PHABSIM work described here is the first stage in the process of developing a more ecologically acceptable flow regime in the Upper Derwent catchment. The decision on the final implementation will be subject to further resource modelling and negotiation between the Environment Agency, the water company and local interested stakeholders. Copyright © 2001 John Wiley & Sons, Ltd.
Ecological integrity of river–floodplain systems—assessment by dragonfly surveys (Insecta: Odonata)
Authors: Chovanec Andreas , Waringer Johann 
Published: January 2005

AbstractDragonflies are reliable indicators of the ecological quality of land–water ecotones, habitat heterogeneity and the hydrological dynamics of water bodies. In recent years, surveys of dragonfly communities have become a powerful tool for the ecological assessment of floodplain areas. The goal of this paper is to present a new approach towards assessing the ecological integrity of river–floodplain systems by analysing resident breeding dragonfly species. The methodology is based on experiences with existing approaches using macroinvertebrates as bioindicators, in particular, calculations of saprobic indices, longitudinal zonation and functional feeding group patterns. In addition to the total number of species and the number of sensitive species, the ‘Odonate Habitat Index’ (OHI) is a key element of the assessment method. It indicates characteristic features of a river–floodplain system, such as connectivity aspects, flow dynamics and terrestrialization processes. The OHI is calculated from the species‐specific habitat values (expressing habitat preferences), abundances and the species‐specific indication weight, which distinguishes eurytopic from stenotopic species. The comparison of the status quo with a reference condition allows an assessment of individual water bodies and/or of a whole area in a five‐tiered classification scheme. The approach presented may also be used for the evaluation of restoration measures (e.g. reconnection of side arms) and for the definition of management objectives. Apart from the methodological framework, the results of a first application of this approach are presented in the paper as well. The study areas were selected floodplain systems of the Austrian section of the Danube and man‐made inshore structures of the impounded Danube section in Vienna. Copyright © 2001 John Wiley & Sons, Ltd.
Sustainability indicators: the problem of integration
Authors: Morse Stephen , McNamara Nora , Acholo Moses , Okwoli Benjamin 
Published: January 2005

AbstractSustainability indicators (SIs) are increasingly seen as important tools in the implementation of sustainable development. Numerous suggested SI lists and matrices exist, but a remaining problem is how these diverse SIs are to be integrated into an answer as to whether something is sustainable or not. In some studies of sustainability workers have adopted a quantitative integration approach whereby SIs are given numerical values and integrated mathematically to produce a value for sustainability. In this paper the authors discuss SI integration by drawing upon the results of a six‐year research project based in a village in Nigeria. They conclude that an element of'qualitative integration' incorporating value judgements and subjectivity is inevitable with a concept such as sustainability, even if one begins with what may seem like sharp and quantitative SIs. It is argued that SIs are primarily a product of development intervention rather than a desire to understand, and as a result carry with them the desired characteristics, from the donor perspective, of efficiency and accountability. Copyright © 2001 John Wiley & Sons, Ltd and ERP Environment
Sustainable development: is it achievable within the existing international political economy context?
Authors: Carvalho Georgia O. 
Published: January 2005

AbstractThe past few years have not been particularly auspicious in environmental terms; there is increasing evidence of a fairly widespread environmental crisis, increasing the pressure to rethink many of the concepts related to environment and development. Among the important concepts that need to be revisited and further explored is ‘sustainable development’. This paper examines the roots of the sustainable development concept and argues that within the current international political economic system it would be nearly impossible to adopt development strategies that are conducive to truly sustainable development. Four hypotheses about international political economic structures and their relationship to sustainable development are examined. The analysis builds on the linkages between historical processes, international political economic structures, international institutions and the development process posited by globalist theories. The paper concludes that profound changes in economic, political and social structure would be necessary to foster sustainable development. Copyright © 2001 John Wiley & Sons, Ltd and ERP Environment
Surface structuring and phase formation in thin metallic layers deposited at various temperatures
Authors: Markwitz A. , Matz W. , Short K. , Waldschmidt M. 
Published: January 2005

AbstractScanning electron microscopy, atomic force microscopy and x‐ray diffraction analyses were performed for the study of the influence of substrate temperature during deposition on the surface structuring and phase formation on thin metallic double layers. Thin layers of Au, Al and Cr were deposited at 150 and 300 °C on 30 nm thick Cu layers evaporated on Si (100) wafer substrates. Possible applications of such layers are Raman‐active surfaces and model layers for diffusion experiments. The topographical investigation revealed an increase of surface structuring with temperature that is related to the formation of intermetallic and oxide phases. At 150 °C deposition temperature, the average roughness (Ra) of the films was determined to be 2–3 nm and the surfaces appeared smooth. In agreement with previous ion beam analysis measurements, a significant surface roughness occurred at 300 °C, depending on the type of the metallic films. The lowest average surface roughness value was measured for the Al/Cu/Si system (Ra = 14.1 nm) and, about double the roughness was measured for the Au/Cu/Si and Cr/Cu/Si layer systems. In contrast, for single Cu layers a high value of Ra = 93.0 nm was determined. The combined analyses showed that the formation of intermetallic phases such as AlCu and CuAl2, reduces a surface roughening. However, the formation of oxide phases such as CuO2, increases, the average surface roughness. Copyright © 2002 John Wiley & Sons, Ltd.
Atomic force microscopy study of ultrafiltration membranes: solute interactions and fouling in pulp and paper processing
Authors: Richard Bowen W. , Stoton J. Austin G. , Doneva Teodora A. 
Published: January 2005

AbstractAtomic force microscopy (AFM) has been used to quantify directly the interaction (adhesion) of cellubiose and cellulose with two polymeric ultrafiltration membranes of similar molecular weight cut‐off (MWCO) but different materials (ES404 and EM006, PCI Membranes, UK). Membrane ES404 is made from polyethersulphone alone and EM006 is made of a polyethersulphone–polyacrylate blend chosen specifically to increase the hydrophilic properties and decrease the fouling properties of the membrane. Cellubiose‐modified silica probes were used to quantify the interaction of cellubiose with the clean membranes. Pure cellulose probes were used to quantify the interaction of cellulose with both clean and cellubiose‐fouled membranes. All measurements were made in 10−2 M NaCl solution. It was found that the cellubiose‐modified probes had three times greater adhesion with the ES404 than with the EM006 membrane. The pure cellulose probe also had greater adhesion with the ES404 membrane. Cellubiose fouling of both membranes gave close to an order of magnitude increase in the adhesion of the cellulose probe. The results show how AFM in conjunction with the colloid probe technique can elucidate surface interactions in solution, in particular how macromolecular adsorption can modify the subsequent adhesion of particulates. Copyright © 2002 John Wiley & Sons, Ltd.
A non‐parametric method for the comparison of partial areas under ROC curves and its application to large health care data sets
Authors: Zhang Dong D. , Zhou Xia‐Hua , Freeman Daniel H. , Freeman Jean L. 
Published: January 2005

AbstractThe receiver operating characteristic (ROC) curve is a statistical tool for evaluating the accuracy of diagnostic tests. Investigators often compare the validity of two tests based on the estimated areas under the respective ROC curves. However, the traditional way of comparing entire areas under two ROC curves is not sensitive when two ROC curves cross each other. Also, there are some cutpoints on the ROC curves that are not considered in practice because their corresponding sensitivities or specificities are unacceptable. For the purpose of comparing the partial area under the curve (AUC) within a specific range of specificity for two correlated ROC curves, a non‐parametric method based on Mann–Whitney U‐statistics has been developed. The estimation of AUC along with its estimated variance and covariance is simplified by a method of grouping the observations according to their cutpoint values. The method is used to evaluate alternative logistic regression models that predict whether a subject has incident breast cancer based on information in Medicare claims data. Copyright © 2002 John Wiley & Sons, Ltd.
A seminar series in applied biostatistics for clinical research fellows, faculty and staff
Authors: Deutsch Reena 
Published: January 2005

AbstractFamiliarity with experimental design and statistical analysis techniques is necessary for investigators to conduct state‐of‐the‐art research in clinical medicine. A wide range of options for biostatistical training is available. These include formal academic courses for credit, one‐on‐one education offered under the guise of consultation, self‐paced textbook or computer learning, intensive short courses, portions of extended courses spanning an assortment of other subjects, and a continuing series of seminars or lectures covering selected topics in statistics. The latter structure is described in this article. We offered an eight‐week lecture series focusing on a new topic in biostatistics each week. The course targeted clinical faculty, postdoctoral fellows, residents, and other interested research staff at a large medical research institution. The series focused on interpretation of medical journal articles with regard to statistical issues. Another objective was to provide information to increase a participant's expertise in the design of research studies. Guidance was offered for effective communication with collaborating biostatisticians. The format and contents of the seminar series are described. Aspects of the course that proved to be successful are discussed. Copyright © 2002 John Wiley & Sons, Ltd.
Statistical approaches to establishing vaccine safety
Authors: Dragalin Vladimir , Fedorov Valerii , Cheuvart Brigitte 
Published: January 2005

AbstractIn a vaccine safety trial, the primary interest is to demonstrate that the vaccine is sufficiently safe, rejecting the null hypothesis that the relative risk of an adverse event attributable to the new vaccine is above a prespecified value, greater than one. We evaluate the exact probability of type I error of the likelihood score test, with sample size determined by normal approximation, by enumeration of the binomial outcomes in the rejection region and show that it exceeds the nominal level. In the case of rare adverse events, we recommend the Poisson approximation as an alternative and develop the corresponding conditional and unconditional tests. We give sample size and power calculations for these tests. We also propose optimal randomization strategies which either (i) minimize the total number of adverse cases or (ii) minimize the expected number of subjects when the vaccine is unsafe. We illustrate the proposed methods using a hypothetical vaccine safety study. Copyright © 2002 John Wiley & Sons, Ltd.
A quasi‐exact method for the confidence intervals of the difference of two independent binomial proportions in small sample cases
Authors: Chen Xun 
Published: January 2005

Abstract In this paper we propose a quasi‐exact alternative to the exact unconditional method by Chan and Zhang (1999) estimating confidence intervals for the difference of two independent binomial proportions in small sample cases. The quasi‐exact method is an approximation to a modified version of Chan and Zhang's method, where the two‐sided p‐value of an observation is defined by adding to the one‐sided p‐value the sum of all probabilities of more ‘extreme’ events in the unobserved tail. We show that distinctively less conservative interval estimates can be derived following the modified definition of the two‐sided p‐value. The approximations applied in the quasi‐exact method help to simplify the computations greatly, while the resulting infringements to the nominal level are low. Compared with other approximate methods, including the mid‐p quasi‐exact methods and the Miettinen and Nurminen (M&N) asymptotic method, our quasi‐exact method demonstrates much better reliability in small sample cases. Copyright © 2002 John Wiley & Sons, Ltd.
Semi‐parametric models of long‐ and short‐term survival: an application to the analysis of breast cancer survival in Utah by age and stage
Authors: Tsodikov A. 
Published: January 2005

AbstractA flexible class of semi‐parametric survival models is proposed that takes account of long‐ and short‐term covariate effects in cancer survival. The diversity of responses described by the models include non‐proportional and crossing survival curves as well as a fraction of long‐term survivors. Restricted non‐parametric maximum likelihood estimation procedures (RNPMLE) are developed to provide point estimates, confidence intervals and tests for the models. Numerical algorithms to fit semi‐parametric survival models are emphasized. The methods are applied to analyse post‐treatment survival of breast cancer patients diagnosed in Utah by age and stage. Copyright © 2002 John Wiley & Sons, Ltd.
Some further results on incorporating risk factor information in assessing the dependence between paired failure times arising from case‐control family studies: an application to prostate cancer
Authors: Hsu Li , Prentice Ross L. , Stanford Janet L. 
Published: January 2005

AbstractIn a typical case‐control family study, detailed risk factor information is often collected on cases and controls, but not on their relatives for reasons of cost and logistical difficulty in locating the relatives. The impact of missing risk factor information for relatives on estimation of the strength of dependence between the disease risk of pairs of relatives is largely unknown. In this paper, we extend our earlier work on estimating the dependence of ages at onset between paired relatives from case‐control family data to include covariates on cases and controls, and possibly relatives. Using population‐based case‐control families as our basic data structure, we study the effect of missing covariates for relatives and/or cases and controls on the bias of certain dependence parameter estimators via a simulation study. Finally we illustrate various analyses using a case‐control family study of early onset prostate cancer. Copyright © 2002 John Wiley & Sons, Ltd.
Bayesian estimation of the proportion of treatment effect captured by a surrogate marker
Authors: Cowles Mary Kathryn 
Published: January 2005

AbstractSurrogate endpoints in clinical trials are biological markers or events observable earlier than the clinical endpoints (such as death) that are actually of primary interest. The ‘proportion of treatment effect captured’ by a surrogate endpoint (PTE) is a frequentist measure intended to address the question of whether trials based on a surrogate endpoint reach the same conclusions as would have been reached using the true endpoint. The question of inferential interest is whether PTE for a given marker exceeds some threshold value, say 0.5. Calculating PTE requires fitting two different models to the same data. We develop a Markov chain Monte Carlo based method for estimating the Bayesian posterior distribution of PTE. The new method conditions on the truth of a single model. Obtaining the full posterior distribution enables direct statements such as ‘the posterior probability that PTE>0.5 is 0.085’. Furthermore, credible sets do not depend on asymptotic approximations and can be computed using data sets for which the frequentist methods may be inaccurate or even impossible to apply. We illustrate with Bayesian proportional hazards models for clinical trial data. As a by‐product of developing the Bayesian method, we show that the frequentist estimate of PTE also may be computed from quantities in a single model and calculate frequentist confidence intervals for PTE that tend to be narrower than those produced by standard methods but that provide equally good coverage. Copyright © 2002 John Wiley & Sons, Ltd.