bluuebunny/crossref_metadata_2025 huggingface dataset:
Cost effectiveness of adding leflunomide to a 5‐year strategy of conventional disease‐modifying antirheumatic drugs in patients with rheumatoid arthritis
Authors: Maetzel Andreas , Strand Vibeke , Tugwell Peter , Wells George , Bombardier Claire
Published: January 2003

Objective

To estimate, from a public payer's perspective, the 5‐year cost effectiveness of adding leflunomide (LEF) to a sequence of disease‐modifying antirheumatic drugs (DMARDs) representative of a typical rheumatoid arthritis (RA) management approach adopted by Canadian rheumatologists.

Methods

A DMARD sequence including LEF was compared with one excluding it, using a 5‐year simulation model where patients with RA cycle through different treatment regimens. Data were obtained through a systematic literature search (drug withdrawal rates, number and type of adverse events, American College of Rheumatology 20% responder status) and separately conducted surveys (choice of DMARD sequence, management of adverse events). Costs for adverse event management were calculated using the Ontario Schedule of Benefits, and monitoring costs were calculated according to official Canadian product monograph recommendations. Wholesale prices of all drugs were adjusted by the allowable markup and prescription fees. Utilities (as measured by the standard gamble [SG] and rating scale [RS] techniques) were obtained from 482 patients who participated in a 1‐year randomized controlled trial that compared LEF, methotrexate, and placebo. Costs and utilities were discounted by 3%. Probabilistic sensitivity analysis was performed.

Results

Adding LEF to a conventional strategy of DMARDs increased the 5‐year management costs by $1,231 compared with the strategy without LEF, which results in a cost‐effectiveness ratio of $13,096 per additional year of response to treatment, and cost‐utility ratios of $54,229 (RS) and $71,988 (SG) per quality‐adjusted life‐year gained.

Conclusion

Adding LEF as a new option to a conventional sequence of DMARDs extends the time patients may benefit from DMARD therapy at a reasonable cost effectiveness and cost utility. LEF data are limited to clinical trials; data from observational studies would be needed to corroborate these findings.
Interstitial lung disease in polymyositis and dermatomyositis
Authors: Marie I. , Hachulla E. , Chérin P. , Dominique S. , Hatron P.‐Y. , Hellot M.‐F. , Devulder B. , Herson S. , Levesque H. , Courtois H.
Published: January 2003

Objectives

To assess prevalence, characteristics, and long‐term outcome of interstitial lung disease (ILD) in polymyositis (PM) and dermatomyositis (DM). To determine predictive variables of ILD course in PM/DM, and to define both clinical and biochemical features associated with ILD onset in PM/DM.

Methods

The medical records of 156 consecutive PM/DM patients in 3 medical centers were reviewed.

Results

Thirty‐six PM/DM patients (23.1%) developed ILD. We observed that 19.4% of patients with ILD had resolution of pulmonary disorders, whereas 25% experienced ILD deterioration. Morbidity and mortality rates were as high as 13.9% and 36.4%, respectively, in PM/DM patients with ILD. Parameters of PM/DM that related to ILD poor outcome were identified as follows: Hamman‐Rich–like pattern, initial diffusing capacity of carbon monoxide <45%, neutrophil alveolitis, and histologic usual interstitial pneumonia. Additionally, for the group with ILD, polyarthritis, higher values of erythrocyte sedimentation rate and C‐reactive protein, presence of anti–Jo‐1 antibody, and characteristic microangiopathy were significantly more frequent.

Conclusion

Our series underlines the high frequency of ILD in PM/DM patients, resulting in increased morbidity and mortality rates. It also indicates that PM/DM patients should routinely be screened for ILD, even those patients without anti–Jo‐1 antibody, because 69% of our ILD patients were seronegative for the anti–Jo‐1 antibody. Our findings further suggest that PM/DM patients presenting with factors predictive of ILD poor outcome may require more aggressive therapy.
Arthritis beliefs and self‐care in an urban American Indian population
Authors: Kramer B. Josea , Harker Judith O. , Wong Andrew L.
Published: January 2003

Objective

To describe beliefs and self‐care strategies of American Indians with chronic arthritis joint pain.

Method

In‐depth interviews were conducted with a convenience sample of urban‐dwelling American Indians (n = 56) concerning self‐care and beliefs about arthritis; objective measures of arthritis disease activity were obtained through standardized interview protocols.

Results

Joint pain was not generally assumed to be arthritis nor directly related to aging. Belief that chronic pain affecting multiple joints was a serious and unexpected condition oriented American Indians' decisions to seek medical attention. However, verbal communications about pain may be subtle or under emphasized. Few coping strategies were used to control either chronic or episodic pain.

Conclusions

Chronic arthritis pain may not be optimally managed in this population. Cultural assessment should recognize that American Indian patients may understate serious symptoms. Community educational interventions should target this population to enhance self‐care, pain management, and communication of arthritis symptoms to physicians.
Use of NSAIDs, COX‐2 inhibitors, and acetaminophen and associated coprescriptions of gastroprotective agents in an elderly population
Authors: Rahme Elham , Marentette Michael A. , Kong Sheldon X. , Lelorier Jacques
Published: January 2003

Objectives

To identify determinants of cyclooxygenase 2 (COX‐2) inhibitor versus nonsteroidal antiinflammatory drug (NSAIDs) or acetaminophen prescription in seniors; and to compare gastroprotective agent coprescriptions.

Methods

Administrative medical records were obtained from the government of Quebec health insurance agency. Three cohorts were formed based on prescriptions at study entry: COX‐2 inhibitors, NSAIDs, or acetaminophen. Logistic regressions were used to adjust for potential confounders.

Results

We identified 42,267 patients taking COX‐2 inhibitors, 8,235 taking NSAIDs, and 19,716 taking acetaminophen. Determinants of utilizing COX‐2 inhibitors versus NSAIDs and versus acetaminophen, respectively, include: female gender (odds ratio [OR] 1.47; 95% confidence interval [95% CI] 1.39–1.55 and OR 1.17; 95% CI 1.12–1.22); musculoskeletal diseases (OR 1.87; 95% CI 1.76–2.00 and OR 2.20; 95% CI 2.10–2.31); and prior gastrointestinal hospitalization (OR 1.82; 95% CI 1.19–2.78 and OR 0.77; 95% CI 0.64–0.92). Gastroprotective agent coprescriptions were lower with COX‐2 inhibitors than NSAIDs: OR 0.53; 95% CI 0.48–0.58.

Conclusions

COX‐2 inhibitors were more commonly used than NSAIDs in patients with musculoskeletal diseases and those with prior gastrointestinal hospitalizations. Adjusted odds ratios showed a 47% decrease in gastroprotective agent coprescriptions with COX‐2 inhibitors compared with NSAIDs.
Benign angiopathy of the central nervous system: Cohort of 16 patients with clinical course and long‐term followup
Authors: Hajj‐Ali Rula A. , Furlan Anthony , Abou‐Chebel Alex , Calabrese Leonard H.
Published: January 2003

Objective

Benign angiopathy of the central nervous system (BACNS) is a subset of primary angiitis of the central nervous system (PACNS) with favorable outcome, not requiring prolonged immunosuppression. We retrospectively studied the clinical characteristics and prospectively assessed long‐term outcome in a cohort of BACNS patients.

Methods

Patients meeting the clinical description for BACNS, evaluated and treated by a single investigator, were included. Data on demographics, signs and symptoms, laboratory studies, neuroimaging, brain biopsy, treatment, and complications were recorded. The long‐term assessment included a phone interview utilizing the Barthel index and a specifically designed cognitive index.

Results

Sixteen cases met the inclusion criteria. Mean age was 40 years (range 10–66 years) with female:male ratio of 4.3:1 and a mean followup period of 35 months (0–128 months). Headache was the most common presenting symptom, seen in 88% of the cases, followed by focal symptoms (63%), and diffuse symptoms (44%). All patients had highly abnormal cerebral angiography, and magnetic resonance imaging abnormalities were present in 77% (10 of 13). Severe cerebral spinal fluid (CSF) abnormalities were present in 1 patient (7%). All followup cerebral angiography showed marked improvement. Recovery was demonstrated in 94% of the patients, 6% relapsed, and there were no deaths. Of patients assessed by the Barthel index, 71% showed no disability and 29% had mild disability.

Conclusion

There is a PACNS subset characterized by acute presentation (most commonly headache), normal to mildly abnormal CSF findings, female predominance, and highly abnormal cerebral angiography (reversible after treatment), requiring less intensive treatment than has been traditionally used.
Evaluation of the smallest detectable difference in outcome or process variables in ankylosing spondylitis
Authors: Auleley Guy‐Robert , Benbouazza Karima , Spoorenberg Anneke , Collantes Eduardo , Hajjaj‐Hassouni Najia , van der Heijde Desirée , Dougados Maxime
Published: January 2003

Objective

To evaluate the smallest detectable difference (SDD) of symptomatic outcome or process variables in ankylosing spondylitis (AS) patients from various countries.

Methods

Thirty consecutive AS patients with axial involvement were recruited from 1 center in each of 4 countries (Spain, Morocco, France, The Netherlands), for a total of 120 patients. Fourteen variables were studied in 6 domains: pain (3 variables), stiffness (1 variable), function (2 variables), spinal mobility (3 variables), patient global assessment (4 variables), and the domain of enthesiopathy (1 variable). All patients were evaluated twice within a 1‐week period during which no clinical or therapeutic change occurred. Intracenter reliability was evaluated using the intraclass correlation coefficient (ICC). The SDD was determined using the Bland‐Altman method.

Results

Of the 14 variables evaluated in the 120 patients (82% males, 42 ± 12 years old, with a mean disease duration of 17 ± 13 years), only the SDD for the variable occiput‐to‐wall distance showed statistically significant difference among centers. For the entire group, the SDD, expressed as percentage of the range of the variable, varied from 10% (Mander enthesis index) to 39% (spinal pain at night last week). The intraobserver reliability was good (ICC > 0.80) except for the variables morning stiffness and modified Schober test (ICCs of 0.76 and 0.60, respectively).

Conclusion

This study suggests that the evaluation of AS patients is homogenous and reliable in different centers of different European and North African countries. Evaluation of the SDD of the symptomatic outcome or process variables is a starting point to determine the minimum clinically important difference, permitting the presentation of results of clinical studies on an individual basis.
Minor impact of juvenile arthritis on nutritional status in young adult patients
Authors: Haugen Margaretha A. , Lien Gunhild , Flatø Berit , Kvammen Janne A. , Vinje Odd , Sørskaar Dag , Førre; Øystein
Published: January 2003

Objective

Growth abnormalities and poor nutritional status have been reported in children with juvenile idiopathic arthritis (JIA). The aim of this study was to evaluate the impact of juvenile chronic rheumatic disease on current nutritional status in adult patients in remission or with active disease.

Methods

One hundred thirty‐eight women and 82 men, aged >20 years, with JIA were studied after a mean disease duration of 15.5 ± 2.3 years. Eighty‐four (61%) of the women and 49 (60%) of the men were in remission. Forty‐one healthy women and 54 healthy men served as a reference group. Body composition was analyzed by dual‐energy x‐ray absorptiometry.

Results

There was no difference in height or body mass index (BMI) between patients and healthy subjects. However, female patients with systemic disease had significantly reduced BMI compared with those with pauciarticular JIA (P < 0.001), and female patients who used or had been using corticosteroids had significantly lower weight, height, and BMI compared with the patients who had never used corticosteroids (P < 0.05). Female patients in remission had significantly more lean body mass compared with healthy controls (P < 0.05) and significantly less body fat was found in both women and men (P < 0.01 for both). Patients with active disease had the same amount of lean body mass as the healthy controls, but significantly less body fat (P < 0.05 for women and P < 0.01 for men).

Conclusion

Adult patients with JIA had attained normal height, weight, and BMI, with the exception of women with systemic JIA and those who were using or had used corticosteroids. Patients with JIA in remission seemed to have a better nutritional status than healthy subjects.
Attentional functioning in fibromyalgia, rheumatoid arthritis, and musculoskeletal pain patients
Authors: Dick Bruce , Eccleston Chris , Crombez Geert
Published: January 2003

Objectives

To investigate whether chronic pain patients have deficits in attentional functioning compared with pain‐free controls, and whether fibromyalgia patients have larger deficits in attentional functioning compared with rheumatoid arthritis and musculoskeletal pain patients.

Methods

Sixty patients (20 in each of 3 patient groups) and 20 pain‐free controls completed measures assessing pain intensity, mood, pain‐related disability, somatic awareness, and catastrophic thinking about pain. Attentional functioning was assessed using an age‐standardized, ecologically valid test battery. Analyses were made of between‐group differences.

Results

Sixty percent of patients had at least one score in the clinical range of neuropsychological impairment, independent of demography and mood. Fibromyalgia patients were more anxious and somatically aware than rheumatoid arthritis or musculoskeletal pain patients, but did not show larger attentional deficits than other patient groups.

Conclusion

All 3 groups of chronic pain patients, regardless of diagnosis, had impaired cognitive functioning on an ecologically sensitive neuropsychological test of everyday attention.
The legislation of environmental disclosures in three Nordic countries—a comparison
Authors: Nyquist Siv
Published: January 2003

This paper compares the legislation in Denmark, Norway and Sweden concerning what kind of environmental information firms must disclose. These three Nordic countries have great similarities regarding accounting legislation and standards. However, Denmark has chosen a different way to force firms to disclose their environmental performance compared with Norway and Sweden. Danish firms must deliver separate ‘green accounts’, while Norwegian and Swedish firms are bound to report on environmental issues in the administrative report. The Norwegian and Swedish firms' information mainly addresses the financial consequences of environmental impact and the Norwegian legislation is also found to be more extensive than the Swedish legislation. The information from the Danish firms addresses society in general. The comparison indicates some interesting topics for further analysis, e.g. how the extensive demands in Norway for information about products' impacts when discharged may be fulfilled. As a background for this comparison, an outline of the discussions about voluntary versus regulated environmental information is given as well as an overview of some international standards and recommendations concerning firms' environmental disclosures. Copyright © 2003 John Wiley & Sons, Ltd. and ERP Environment.
An ‘incitement to discourse’: benchmarking as a springboard to sustainable development
Authors: Springett Delyse
Published: January 2003

Benchmarking, while belonging to the array of instruments associated with eco‐efficiency, eco‐modernism and ‘political sustainability’, provides a way in which corporations can be held to account in terms of their environmental and social responsibility. New Zealand lacked such benchmarks until the annualSurvey of Corporate Environmental Responsivenesswas introduced for top companies by turnover in 1999, exposing the myth of ‘clean and green’ New Zealand as far as environmental management of business was concerned, but providing a measure that has become a driver for many companies. The paper discusses outcomes of the benchmarking survey and describes how it has been employed as a Foucauldian ‘incitement to discourse’ with a focus group of participating companies, engaging them in a more dialectical discourse of sustainable development based in Critical Theory and perspectives from Foucault. Maori speak of their ‘turangawaewae’–having a ‘place to stand’. The survey provided the broader research programme with that place to stand in terms of creating a meaningful position for the researchers, and a degree of legitimacy, within the business context. Copyright © 2003 John Wiley & Sons, Ltd. and ERP Environment.
Consumers and green electricity: profiling potential purchasers
Authors: Rowlands Ian H. , Scott Daniel , Parker Paul
Published: January 2003

Globally, consumers are beginning to be able to choose their electricity supplier. Increasing concerns about the environment are prompting some of them to consider ‘green’ electricity—that is, electricity that has been generated by more environmentally sustainable means (for example, solar power or wind power). This article profiles the potential purchaser of green electricity. Drawing upon the literature on green product purchasers more generally, three sets of hypotheses are presented—more specifically, it is proposed that those who would pay increasingly higher premiums for green electricity are more likely to possess particular demographic characteristics, attitudinal characteristics and socialization characteristics. Responses from a survey distributed in a major Canadian metropolitan area are then examined. Attitudinal characteristics—specifically ecological concern, liberalism and altruism—best identify the potential purchasers of green electricity. Suggestions for managers and marketers are made following these findings. Directions for future research are also presented. Copyright © 2003 John Wiley & Sons, Ltd. and ERP Environment.
UK environmental policy and the small firm: broadening the focus
Authors: Revell Andrea , Rutherfoord Robert
Published: January 2003

The poor environmental performance of small and medium‐sized enterprises (SMEs) in the UK has been attributed to a wide range of barriers, both internal and external to the firm. However, the debate has seldom considered the interplay of factors beyond ‘the firm’. In order for the debate to progress we emphasize the importance of situating the environmental practices of small firms within a context of national policy arrangements. A lack of institutional enfranchisement for SMEs in the UK is a key factor in understanding why environmental policies have yet to be successful in encouraging more environmentally proactive behaviour within this sector. Copyright © 2003 John Wiley & Sons, Ltd. and ERP Environment.
The ‘greening’ of tourism micro‐businesses: outcomes of focus group investigations in South East Cornwall
Authors: Vernon Jon , Essex Stephen , Pinder David , Curry Kaja
Published: January 2003

The response of micro‐businesses to sustainability issues, and their use of environmental management tools and systems, are often presented as simply scaled‐down versions of those of larger businesses in the small and medium‐sized enterprise (SME) sector as a whole. This paper presents the findings of a series of focus groups with the owners of tourism micro‐businesses in South East Cornwall about their awareness, understanding and adoption of sustainable tourism practices. The results reveal a complex and diverse response to the concept that resists such generalizations. A genuine need for measures to increase awareness and integrate sustainability issues within business practice is highlighted. Initiatives that do not account for the heterogeneity of the sector are likely to have only limited success. Copyright © 2003 John Wiley & Sons, Ltd. and ERP Environment.
Social inequality and the reduction of ideological dissonance on behalf of the system: evidence of enhanced system justification among the disadvantaged
Authors: Jost John T. , Pelham Brett W. , Sheldon Oliver , Ni Sullivan Bilian
Published: January 2003

According to system justification theory, people are motivated to preserve the belief that existing social arrangements are fair, legitimate, justifiable, and necessary. The strongest form of this hypothesis, which draws on the logic of cognitive dissonance theory, holds that people who are most disadvantaged by the status quo would have the greatest psychological need to reduce ideological dissonance and would therefore be most likely to support, defend, and justify existing social systems, authorities, and outcomes. Variations on this hypothesis were tested in five US national survey studies. We found that (a) low‐income respondents and African Americans were more likely than others to support limitations on the rights of citizens and media representatives to criticize the government; (b) low‐income Latinos were more likely to trust in US government officials and to believe that ‘the government is run for the benefit of all’ than were high‐income Latinos; (c) low‐income respondents were more likely than high‐income respondents to believe that large differences in pay are necessary to foster motivation and effort; (d) Southerners in the USA were more likely to endorse meritocratic belief systems than were Northerners and poor and Southern African Americans were more likely to subscribe to meritocratic ideologies than were African Americans who were more affluent and from the North; (e) low‐income respondents and African Americans were more likely than others to believe that economic inequality is legitimate and necessary; and (f) stronger endorsement of meritocratic ideology was associated with greater satisfaction with one's own economic situation. Taken together, these findings are consistent with the dissonance‐based argument that people who suffer the most from a given state of affairs are paradoxically the least likely to question, challenge, reject, or change it. Implications for theories of system justification, cognitive dissonance, and social change are also discussed. Copyright © 2002 John Wiley & Sons, Ltd.
Human values, utilitarian benefits and identification: the case of meat
Authors: Allen Michael W. , Hung Ng Sik
Published: January 2003

The present studies explored the associations among food's utilitarian benefits, the human values symbolised by meat, individuals' endorsement of those values, and individuals' meat identification, attitudes and consumption. A preliminary study revealed that participants perceived that meat, particularly red meat, symbolises the endorsement of inequality and hierarchy values more than other basic foods. Studies 1 and 2 found that the endorsement of inequality and hierarchy formed the basis to the meat attitudes and consumption of high meat identifiers. Study 2 found that the meat attitudes of high meat identifiers were also founded, though to a lesser extent, in the endorsement of Conservation and rejection of Openness values. Study 1 also showed that food's nutritional benefits did not form the basis of meat consumption among high meat identifiers. Moreover, Study 3 found that informing individuals (in the treatment group) of the nutritional deficiencies of meat did not alter the meat attitudes of high meat identifiers, meat identification per se, or the meat attitudes of individuals who have a predisposition to attend to the symbolic meanings of products. In contrast, the negative nutritional information did produce unfavourable meat attitudes among low meat identifiers and those who have a predisposition to attend to the utilitarian features of products. The formation of meat identification is discussed. Copyright © 2002 John Wiley & Sons, Ltd.
Individualist and collectivist norms: when it's ok to go your own way
Authors: McAuliffe Brendan J. , Jetten Jolanda , Hornsey Matthew J. , Hogg Michael A.
Published: January 2003

We conducted two studies to investigate the influence of group norms endorsing individualism and collectivism on the evaluations of group members who display individualist or collectivist behaviour. It was reasoned that, overall, collectivist behaviour benefits the group and would be evaluated more positively than would individualist behaviour. However, it was further predicted that this preference would be attenuated by the specific content of the group norm. Namely, when norms prescribed individualism, we expected that preferences for collectivist behaviour over individualist behaviour would be attenuated, as individualist behaviour would, paradoxically, represent normative behaviour. These predictions were supported across two studies in which we manipulated norms of individualism and collectivism in an organizational role‐play. Furthermore, in Study 2, we found evidence for the role of group identification in moderating the effects of norms. The results are discussed with reference to social identity theory and cross‐cultural work on individualism and collectivism. Copyright © 2002 John Wiley & Sons, Ltd.
Constructing a minority group identity out of shared rejection: the case of international students
Authors: Schmitt Michael T. , Spears Russell , Branscombe Nyla R.
Published: January 2003

With a sample of international students, we investigated how perceptions of rejection by the host community are related to a sense of identification with other international students. Based on the rejection‐identification model (Branscombe, Schmitt, & Harvey, 1999) we predicted that perceiving prejudice from the host university would be negatively related to psychological well‐being. We expected that group identification with international students would mediate a positive effect of perceived discrimination on self‐esteem, thus suppressing the negative effect of perceiving prejudice on self‐esteem. Consistent with predictions, results supported a model in which identification with international students increased in response to perceiving prejudice and suppressed the costs of perceiving oneself as excluded from the host community. Interestingly, identification with participants' home country was not predicted by perceptions of discrimination. Results are discussed in terms of how minority group members construct group identities in response to the intergroup context. Copyright © 2002 John Wiley & Sons, Ltd.
Immigrant identity of Israeli adolescents from Ethiopia and the former USSR: culture‐specific principles of organization
Authors: Orr Emda , Mana Adi , Mana Yosef
Published: January 2003

The study examines how a sample of 210 high‐school immigrant students (ages 14–15) from Ethiopia and the former USSR socially represent their notion of what klitat aliyah (successful adaptation to Israel) means. Prevalent relevant theories—Berry's model of Acculturation Tendencies (BAT), Social Identity Theory (SIT) and Social Comparison Theory (SCT)—suggest three kinds of patterns by which minority or socially weak groups deal with these kinds of situations. These underlying patterns were tested by a 47‐item questionnaire (with a 4‐point Likert‐like scale), constructed from immigrant narratives regarding their klitat aliyah according to SIT, SCT and BAT categories of adaptation strategies. A Guttman non‐parametric Similarity Structure Analysis (SSA) revealed four‐facet organization of items for both males and females in both sub‐samples. These facets, which reflected social representations of Israeli society, were dubbed: Extended Identity, Rivalry Identity, Secluded Identity and Identity Loss. Results did not confirm the underlying categorization of strategies suggested by SIT and SCT, and partially replicated those suggested by BAT. Copyright © 2002 John Wiley & Sons, Ltd.
Effects of control deprivation on effort expenditure and accuracy performance
Authors: Ric François , Scharnitzky Patrick
Published: January 2003

Theoretical positions lead to diverging predictions regarding the impact of control deprivation on subsequent performance. Learned helplessness research suggests that control deprivation impairs subsequent performance. This effect can be attributed either to a decrease in motivation or to a decrease in attentional resources. In contrast, control motivation hypothesis predicts that control deprivation increases careful processing of incoming information, and thus accuracy performance, unless the task is perceived as ego‐threatening. In order to test these diverging predictions against each other, participants were exposed to zero, one, two, four, six or eight unsolvable (vs. solvable) problems and then asked to complete two letter cancellation tasks. This task allowed independent evaluation of effort expenditure (i.e., the number of letters scanned) and accuracy performance (i.e., percentage of letters correctly marked). Overall, the results were consistent with the predictions of the cognitive explanations of learned helplessness deficit as control deprivation at high levels reduced accuracy performance but not effort expenditure. Unexpectedly, effort expenditure was affected by problem solving activity. These results suggest that control deprivation could heighten motivation and, at the same time, deplete cognitive resources. Copyright © 2002 John Wiley & Sons, Ltd.
Integrating commons dilemma findings in a general dynamic model of cooperative behavior in resource crises
Authors: Mosler Hans‐Joachim , Brucks Wernher M.
Published: January 2003

The research on commons dilemmas is characterized by innumerable published findings, each standing relatively isolated from the other. To date there is little integration of the findings under a unified concept. The present contribution aims to integrate already existing findings in a general dynamic model of cooperative behavior in resource crises by means of computer simulation. The model postulates that people base their decisions regarding resource use on both ecological and social information. Whether or not ecological or social information will dominate, however, depends on people's social values, attributions, and their perceptions of the state of the resource. The advantage of the simulation method used is that successful integration of the findings can be shown explicitly, as the simulation then replicates the experimental data. With the model presented here, it is also possible to let variables work together whose interaction has not yet been investigated in real experiments. For instance, the simulation model allows us to hypothesize that people, in dependency upon their resource uncertainty and in dependency upon their attributions, utilize a resource completely differently if the resource is in an optimal or sub‐optimal condition. Copyright © 2002 John Wiley & Sons, Ltd.
Role conflict and academic procrastination: A self‐determination perspective
Authors: Senécal Caroline , Julien Etienne , Guay Frédéric
Published: January 2003

The purpose of the present study was to propose and test a model of role conflict and academic procrastination. This model posits that non‐self‐determined motivations toward school and interpersonal relationships are positively related to role conflict between these two life domains. In turn, role conflict between school and interpersonal relationships is expected to be positively related to academic procrastination. Participants were 292 university students. Results from structural equation modeling supported the model. It thus appears that self‐determination and role conflict are important to foster our understanding of academic procrastination. Theoretical implications of the findings are discussed. Copyright © 2002 John Wiley & Sons, Ltd.
Patterns of damage in igneous and sedimentary rocks under conditions simulating sea‐salt weathering
Authors: Cardell C. , Rivas T. , Mosquera M.J. , Birginie J.M. , Moropoulou A. , Prieto B. , Silva B. , Van Grieken R.
Published: January 2003

A saline‐spray artificial ageing test was used to simulate the effects produced in granites and sedimentary rocks (calcarenites, micrites and breccia) under conditions in coastal environments. Three main points were addressed in this study: the durability of the different kinds of rock to salt decay, the resulting weathering forms and the rock properties involved in the weathering processes. For this, mineralogical and textural characterization of each of the different rocks was carried out before and after the test. The soluble salt content at different depths from the exposed surfaces was also determined. Two different weathering mechanisms were observed in the granite and calcareous rocks. Physical processes were involved in the weathering of granite samples, whereas dissolution of calcite was also involved in the deterioration of the calcareous rocks. We also showed that microstructural characteristics (e.g. pore size distribution), play a key role in salt damage, because of their influence on saline solution transport and on the pressures developed within rocks during crystallization. Copyright © 2003 John Wiley & Sons, Ltd.
Organic litter: dominance over stones as a source of interrill flow roughness on low‐gradient desert slopes at Fowlers Gap, arid western NSW, Australia
Authors: Dunkerley David
Published: January 2003

Thirty‐six runoff plot experiments provide data on flow depths, speeds, and Darcy–Weisbach friction coefficients (f) on bare soil surfaces, and surfaces to which were added sufficient extra plant litter or surface stones to provide projected cover of 5, 10 and 20 per cent. Precision flow depth data were derived with a computer‐controlled gantry and needle gauge for two different discharges for each plot treatment.

Taking a fixed flow intensity (Reynolds number, Re = 150) for purposes of comparison shows means of f = 17·7 for bare soil surfaces, f = 11·4 for added stone treatments, and f = 23·8 for added litter treatments. Many individual values of f for stone treatments are lower than for the bare soil surface, but all litter treatments show increases in fcompared to bare soil.

The lowering of f in stone treatments relates to the submerged volume that the stones occupied, and the associated concentration of flow onto a smaller part of the plot surface. This leads to locally higher flow intensities and lower frictional drag along threads of flow that the obstacles create.

Litter causes higher frictional drag because the particles are smaller, and, for the same cover fraction, are 100 times more numerous and provide 20 times the edge or perimeter length. Along these edges, which in total exceed 2·5 m g−1 (equivalent to 500 m m−2 for a loading of 2 t ha−1), surface tension draws up water from between the litter particles. This reduces flow depth there, and as a consequence of the lower flow intensity, frictional drag rises. Furthermore, no clear passage remains for the establishment of flow threads.

These findings apply to shallow interrill flows in which litter is largely immobile. The key new result from these experiments is that under these conditions, a 20 per cent cover of organic litter can generate interrill frictional retardation that exceeds by nearly 41 per cent that of a bare soil surface, and twice that contributed by the same cover fraction of surface stones. Even greater dominance by litter can be anticipated at the many dryland sites where litter covers exceed those tested here. Copyright © 2002 John Wiley & Sons, Ltd.
Prediction of the behaviour of landslide dams using a geomorphological dimensionless index
Authors: Ermini L. , Casagli N.
Published: January 2003

Landslide dams are a common phenomenon. They form when a landslide reaches the bottom of a river valley causing a blockage. The first effect of such a dam is the infilling of a lake that inundates the areas upstream, while the possibility of a sudden dam collapse, with a rapid release of the impounded waters, poses a higher flood risk to the downstream areas.

The results of the main inventories carried out to date on landslide dams, have been examined to determine criteria for forecasting landslide dam evolution with particular emphasis on the assessment of dam stability. Not all landslides result in the blockage of a river channel. This only occurs with ones that can move a large amount of material with moderate or high‐velocities. In most cases, these landslides are triggered by rainfall events or high magnitude earthquakes. A relationship also exists between the volume of the displaced material and the landslide dam stability.

Several authors have proposed that landslide dam behaviour can be forecast by defining various geomorphological indexes, that result from the combination of variables identifying both the dam and the dammed river channel. Further developments of this geomorphological approach are presented in this paper by the definition of a dimensionless blockage index. Starting with an analysis of 84 episodes selected worldwide, it proved to be a useful tool for making accurate predictions concerning the fate of a landslide dam. Copyright © 2002 John Wiley & Sons, Ltd.
Dynamic model for constriction scour caused by large woody debris
Authors: Wallerstein N. P.
Published: January 2003

Large woody debris (LWD) can have a significant impact upon local channel morphology by creating scour pools and zones of reduced shear stress in which sediment is deposited. It is important to predict scour depths associated with LWD, as it is becoming increasingly common for debris to be added into river channels to improve sediment retention and create pools for aquatic habitat. Engineered log‐jams should therefore be designed using factor of safety engineering analysis, which includes estimates of associated scour and deposition rates. However, the rate and total depth of scour associated with LWD have not been modelled comprehensively, with authors resorting to the use of generic local and constriction scour models to predict scour depths. Also, constriction scour models presented, to date, do not calculate the rate of scour development. In this paper a model is presented for predicting the rate and total depth of scour associated with a channel constriction. The model is one‐dimensional and is based upon the sediment continuity equation, the calculation of specific head changes through the constricted reach and also allows for a variable free surface elevation above the bed at the constriction. This model could be applied to any channel constriction problem but here is used to determine scour rates and depths associated with deflector‐type LWD jams. Deflector jams are one category of jam type presented in a debris jam classification scheme, in which jam type is a function of the ratio of average riparian tree height to average channel width. Deflector jams, as the name implies, partially block the flow and therefore act as a channel constriction, which results in constriction scour. Copyright © 2002 John Wiley & Sons, Ltd.
The role of sediment specific gravity and availability on cluster evolution
Authors: Papanicolaou A. N. , Strom K. , Schuyler A. , Talebbeydokhti N.
Published: January 2003

The objective of this experimental study was to account for the role of sediment availability and specific gravity on cluster formation and cluster geometric characteristics (spacing and size). To isolate the effects of sediment availability and specific gravity on cluster evolution, mono‐sized spheres were used to simulate the cluster evolutionary cycle. Overall, twelve experimental runs were carried out in the laboratory flume. Six of these tests were performed by using glass spheres (specific gravity, SG = 2·58) and the other six by employing an equal combination of glass and Teflon spheres (SG = 2·12) of the same diameter to evaluate the role of specific gravity on cluster evolution. The three sediment availability conditions that were investigated here simulated isolated gravel elements, pool–riffle sequences and densely packed gravel‐bed. An advanced image analysis technique was employed to track the evolution of cluster microforms and provide quantitative information about the size and shape of clusters and the number of clusters per unit area. The results of this study showed that: (1) sediment availability affects the architecture and size of cluster microforms; and (2) clusters consisting of mono‐sized sediments start disintegrating at twice the incipient conditions. By performing complementary tests for the isolated gravel elements case, it was found that the evolutionary cycle of individual clusters could be described as follows, in order of increasing stress: no cluster→two particle cluster→comet→triangle→rhomboid→break up. Copyright © 2003 John Wiley & Sons, Ltd.
Recent ventifact development on the central Oregon coast, western USA
Authors: Knight Jasper , Burningham Helene
Published: January 2003

The unusual location of ventifacts, on a boulder‐built jetty at the mouth of the Siuslaw River, Oregon coast, western USA, allows ventifact age and wind abrasion rates to be estimated with some precision. The jetty was built mainly between 1892–1901 and extended throughout the twentieth century. Consideration of historical shoreline position and the history of jetty construction and repair suggests the ventifacts have formed since about 1930.

Morphologically the ventifacts are aligned south‐to‐north reflecting winter winds and sediment transport from the adjacent beach. Wind‐parallel grooves and ridges with sharp, sinuous crests are developed on inclined boulder surfaces on top of the jetty and reflect suspended sand transport in wind vortices. Deeply pitted surfaces on steep boulder surfaces nearest the beach reflect impact by saltating sand grains.

Based on present wind regimes (1992–2000) from three regional weather stations, southerly winds above the sand transport threshold occur for 21·9–29·6 per cent of the time. Based on estimated depth of loss from boulder surfaces, wind abrasion rates are calculated to be on the order of 0·24–1·63 mm a−1. This is the first well‐constrained field estimate of ventifact age and ventifaction rate from a modern coastal environment. Copyright © 2003 John Wiley & Sons, Ltd.
Interference processes on scouring at bed sills
Authors: Lenzi Mario A. , Marion Andrea , Comiti Francesco
Published: January 2003

The local scouring downstream of bed sills forming a sequence for bed stabilization in steep channels has been investigated in a laboratory flume. The initial bed slopes ranged from 0·078 to 0·148. The bed alluvium was characterised by a non‐uniform grain size distribution. The results show that when the ratio between the critical water depthhcand the sill spacingLrises above a characteristic value the scouring dynamics become heavily affected by the presence of the downstream sill, associated with the onset of a form of “interference” which renders the scouring process less effective. The difference with an “undisturbed” case is demonstrated. Self‐affinity of scour holes is confirmed and the scour length appears to be the reference parameter from which the scour depth might be evaluated. Copyright © 2003 John Wiley & Sons, Ltd.
Solution of the hyperbolic mild‐slope equation using the finite volume method
Authors: Bokaris J. , Anastasiou K.
Published: January 2003

A finite volume solver for the 2D depth‐integrated harmonic hyperbolic formulation of the mild‐slope equation for wave propagation is presented and discussed. The solver is implemented on unstructured triangular meshes and the solution methodology is based upon a Godunov‐type second‐order finite volume scheme, whereby the numerical fluxes are computed using Roe's flux function. The eigensystem of the mild‐slope equations is derived and used for the construction of Roe's matrix. A formulation that updates the unknown variables in time implicitly is presented, which produces a more accurate and reliable scheme than hitherto available. Boundary conditions for different types of boundaries are also derived. The agreement of the computed results with analytical results for a range of wave propagation/transformation problems is very good, and the model is found to be virtually paraxiality‐free. Copyright © 2003 John Wiley & Sons, Ltd.
Interface reconstruction with least‐square fit and split Eulerian–Lagrangian advection
Authors: Scardovelli Ruben , Zaleski Stephane
Published: January 2003

Two new volume‐of‐fluid (VOF) reconstruction algorithms, which are based on a least‐square fit technique, are presented. Their performance is tested for several standard shapes and is compared to a few other VOF/PLIC reconstruction techniques, showing in general a better convergence rate. The geometric nature of Lagrangian and Eulerian split advection algorithms is investigated in detail and a new mixed split Eulerian implicit–Lagrangian explicit (EI–LE) scheme is presented. This method conserves the mass to machine error, performs better than split Eulerian and Lagrangian algorithms, and it is only slightly worse than unsplit schemes. However, the combination of the interface reconstruction with the least‐square fit and its advection with the EI–LE scheme appears superior to other existing approaches. Copyright © 2003 John Wiley & Sons, Ltd.
Water quality control by bank placement based on optimal control and finite element method
Authors: Kurahashi T. , Kawahara M.
Published: January 2003

This paper presents a method for quality control by bank placement based on an optimal control theory and the finite element method. The shallow water equation is employed for the analysis of the flow condition and the advection‐diffusion equation is used for the analysis of pollutant concentration. The optimal control theory is utilized to obtain a control value for the objective state value. The shear‐slip mesh update method which is suitable for the rotational problem of body is employed. To solve the optimization problem, the time domain decomposition method is applied as a technique of storage requirements reduction. The Sakawa–Shindo method is employed as a minimization technique. The Crank–Nicolson method is applied to the temporal discretization. A method for optimal control of bank placement has been presented. Copyright © 2003 John Wiley & Sons, Ltd.
A domain decomposition approach to compute wave breaking (wave‐breaking flows)
Authors: Iafrati A. , Campana E. F.
Published: January 2003

A heterogeneous domain decomposition approach is followed to simulate the unsteady wavy flow generated by a body moving beneath a free surface. Attention being focused on complex free surface configurations, including wave‐breaking phenomena, a two‐fluid viscous flow model is used in the free surface region to capture the air–water interface (via a level‐set technique), while a potential flow approximation is adopted to describe the flow far from the interface. Two coupling strategies are investigated, differing in the transmission conditions. Both the adopted approaches make use of the inviscid velocity field as boundary condition in the Navier–Stokes solution.

For validation purposes, two different two‐dimensional non‐breaking flows are simulated. Domain decomposition results are compared with both fully viscous and fully inviscid results, obtained by solving the corresponding equations in the whole fluid domain, and with available experimental data. Finally, the unsteady evolution of a steep breaking wave is followed and some of the physical phenomena, experimentally observed, are reproduced. Copyright © 2003 John Wiley & Sons, Ltd.