bluuebunny/crossref_metadata_2025 huggingface dataset:
Light therapy for behavioural and psychological symptoms of dementia
Authors: Skjerve Arvid , Bjorvatn Bjørn , Holsten Fred
Published: May 2004

Objectives

To review literature concerning the efficacy, clinical practicability and safety of light treatment for behavioural and psychological symptoms of dementia (BPSD).

Method

Data collection included computer literature searches (MEDLINE, PsycINFO and Cochrane) and checks of references, covering the period of January 1980–September 2003. Trials were searched for evidence for treatment efficacy and for their consideration of the treatment's clinical practicability and evidence of adverse effects.

Results

Results from randomised controlled trials (RCT) indicated some evidence of improvement in aspects of sleep disturbances and circadian activity rhythmicity. One RCT study indicated better response in patients with vascular dementia compared to Alzheimer's disease. By and large, non‐RCT studies reported improvement in BPSD including sleep disturbances, agitation and activity rhythm disturbances. Few studies commented on the treatment's practicability and safety.

Conclusion

Although there is some evidence for influence of light therapy on sleep and circadian activity rhythmicity, it is not possible to draw any conclusion about efficacy of light therapy for BPSD, or about practicability in clinical settings and safety. There are still too few well designed studies. Suggestions for further research are presented. Copyright © 2004 John Wiley & Sons, Ltd.
5‐HT2A T102C receptor polymorphism and neuropsychiatric symptoms in Alzheimer's disease
Authors: Lam Linda Chiu Wa , Tang Nelson Leung Sang , Ma Suk Ling , Zhang Weimin , Chiu Helen Fung Kum
Published: May 2004

Objective

To investigate the association between 5‐HT2A receptor polymorphism and neuropsychiatric (NP) symptoms in Chinese elderly with Alzheimer's disease (AD).

Methods

This case‐control study evaluated Chinese subjects with AD first presented to an university affiliated psychogeriatric clinic. Eighty‐seven subjects with NINCDS‐ADRDA diagnosis for probable and possible AD were recruited consecutively from the psychogeriatric clinics of the Prince of Wales Hospital in Hong Kong. 5‐HT2A receptor polymorphisms were examined by polymerase chain reaction (PCR), enzyme digestion and gel electrophoresis. NP symptoms were assessed by the Chinese version of the Neuropsychiatric Inventory (NPI).

Results

The genotype frequencies were significantly different in subjects with regards to the presentation of delusions, aggression, aberrant motor behavior and apathy (Pearson Chi Squares, p < 0.05). If only homozygote states were included, there were significantly fewer subjects of CC genotype with delusion (Pearson chi square, p < 0.05).

Conclusions

Specific NP symptoms in AD were significantly associated with 5‐HT2A receptor polymorphisms. Possible ethnic differences in the behavioral expression of 5‐HT2A receptor polymorphisms are worthy of further exploration. Copyright © 2004 John Wiley & Sons, Ltd.
What causes problems in Alzheimer's disease: attributions by caregivers. A qualitative study
Authors: Paton Joni , Johnston Kate , Katona Cornelius , Livingston Gill
Published: May 2004

Objective

To gain insight into caregivers' understanding of the causes of behaviours they find problematic in people with Alzheimer's disease in order to inform the development of educational strategies.

Methods

A qualitative, semi‐structured interview was used. Participants were 205 caregivers for a person with Alzheimer's disease, all of whom were aware of the diagnosis and who had been recruited as part of a larger longitudinal study. Participants were from inner‐city and suburban London/semi‐rural Essex. The main outcome measures were caregivers' understanding of: the cause of problematic behaviour; the ability of the person with dementia to control this behaviour; the prognosis of the illness.

Results

Most carers attribute the cognitive, behavioural and psychological symptoms of dementia to causes other than dementia; many believe that the person with dementia has control over their behaviour and substantial numbers believe the person with dementia will return to normal.

Conclusions

This study suggests that providing facts about the illness to caregivers is not enough, as caregivers may not understand that the symptoms they observe are related to the diagnosis. Education by clinicians should focus on the understanding of caregivers and in particular explore the caregivers' attributions of the symptoms which are present in the person for whom they care. Copyright © 2004 John Wiley & Sons, Ltd.
Family functioning in the caregivers of patients with dementia
Authors: Heru Alison M. , Ryan Christine E. , Iqbal Asma
Published: May 2004

Background

Caregiver burden has been extensively studied in the dementia population. The marital relationship has been suggested as a mediational model through which variables influence the caregiver and contribute to the experience of burden or reward.

Objectives

This study examines family functioning, caregiver burden and reward and quality of life in 38 family members caring for a relative with dementia.

Methods

Caregivers of out‐patients with dementia completed self report questionnaires.

Results

63% of caregivers were female with a mean age of 62 years. Patient mean age was 73 years. The average number of caregiving years was 3.1. Caregivers were more likely to be spouses (61%) than children (29%) or other relatives (11%). Despite the fact that caregivers reported that their relatives were moderately disabled, they perceived more reward than burden. Caregivers who reported poor family functioning had higher ratings of strain and burden. Family functioning in these caregivers was poorest in the dimensions of affective responsiveness, problem solving and communication but it was also impaired in roles and affective involvement.

Conclusions

Assessing a family's functioning may be an important factor in the care of the dementia patient and his/her family. Copyright © 2004 John Wiley & Sons, Ltd.
Depression in first generation labour migrants in Western Europe: the utility of the Center for Epidemiologic Studies Depression Scale (CES‐D)
Authors: Spijker J. , van der Wurff F. B. , Poort E. C. , Smits C. H. M. , Verhoeff A. P. , Beekman A. T. F.
Published: May 2004

Objective

The number of elderly migrants from Turkish and Moroccan descent in Western Europe will increase sharply in the coming decades. Identifying depressed elderly migrants necessitates a screening instrument that is both acceptable and has good psychometric properties. This study examines the utility of Turkish and Arabic translations of the Center for Epidemiologic Studies Depression Scale (CES‐D) among elderly labour migrants from Turkish and Moroccan descent in the Netherlands.

Method

The data were derived from a community based health survey among 304 native Dutch, 330 Turkish and 299 Moroccan migrants, aged 55–74 years, living in Amsterdam, the Netherlands. Acceptability, reliability, convergent and construct validity were studied.

Results

Acceptability of the CES‐D was satisfactory, although Moroccan migrants and Turkish females had difficulty answering one or more of the (interpersonal) items from the CES‐D. Translated versions of the CES‐D proved to be highly internal consistent and have good convergent validity in both Turkish and Moroccan elderly. Depressed and somatic items were much more intermingled in Turkish and Moroccan elderly compared to earlier studies and native Dutch elderly. This fits to the hypothesis that Turkish and Moroccan elderly migrants tend to somatize their depressive symptoms much more than native Western elderly.

Conclusion

The utility of the CES‐D for elderly migrants of Turkish and Moroccan descent was found to be satisfactory. Copyright © 2004 John Wiley & Sons, Ltd.
The effects of light therapy on depressed elders
Authors: Tsai Yun‐Fang , Wong Thomas K. S. , Juang Yeong‐Yuh , Tsai Hsiu‐Hsin
Published: May 2004

Background

Elderly depression has gradually become a severe issue in the health care system. No studies have focused on evaluating the effects of light therapy on the elderly with depression in a subtropical climate area.

Objectives

To evaluate the effects of light therapy on hospitalized, depressed elders living in a subtropical climate area.

Methods

Experimental design was used. For the experimental group, patients sat in front of a light box, receiving 5000 lux in the morning. The light therapy course was administered for 50 minutes per day and lasted for 5 days. The control group did not receive any treatment.

Results

Depressive symptoms were significantly reduced in the experimental group at post‐test but no significant decline was found in the control group.

Conclusions

Based upon the results of this study, light therapy could be used to decrease depressive symptoms in the elderly. Copyright © 2004 John Wiley & Sons, Ltd.
Perceived mental health needs and adequacy of service provision to older people in care homes in the UK: a national survey
Authors: Purandare Nitin , Burns Alistair , Challis David , Morris Julie
Published: May 2004

Objective

To assess perceived need and adequacy of service provision by old age psychiatrists (OAPs) to older people living in care homes in the UK.

Methods

A postal survey of managers of a stratified random sample of 2638 (14% of 18,698) care homes in the UK caring for older residents. Reminders were sent to those not returning the questionnaires.

Results

The response rate was 64% (n = 1689). Forty‐one percent of care home managers felt that at least 50% of their residents needed psychiatric evaluation. Cognitive impairment, depressive symptoms and challenging behaviour was thought to be present in at least a quarter of residents by 78%, 29% and 17% respectively. Thirty‐eight percent of managers reported that their homes ‘never’ received any visits from OAPs and only a half described the current frequency of visits as adequate. Pharmacological advice was perceived to be adequate by about three‐quarters but less than a half perceived non‐pharmacological advice as adequate. Eighty percent wanted more input for staff education and training. Perceived need ( p < 0.001), frequency of visits by OAPs ( p = 0.001), availability of geriatrician ( p = 0.001), amount of non‐pharmacological advice ( p = 0.014) and direct referral access to OAPs for known patients ( p = 0.036) were found to be independent predictors of perceived inadequacy of service provision by OAPs.

Conclusion

The survey highlights the perception of unmet need and inadequacy of service provision by OAPs amongst managers of care homes in the UK. The study findings, if confirmed by direct observational studies, may have a considerable impact on already sparse resources with a need to explore efficacy of different models of care in meeting this need. Copyright © 2004 John Wiley & Sons, Ltd.
Neurosis and mortality in persons aged 65 and over living in the community: a systematic review of the literature
Authors: Dewey Michael E. , Chen Chih‐Mei
Published: May 2004

Background

No previous attempt has been made to synthesise information on mortality and neurosis in older people. Our objective was to estimate the influence on mortality of various types of neurosis in the older population.

Methods

Data sources were: Medline; Embase; and personal files. Studies were considered if they included a majority of persons aged 65 and over at baseline either drawn from a total community sample or drawn from a random sample from the community. Studies which sampled from a larger age range were also included if it was possible to retrieve results about those aged 65 and over. Samples from health care facilities were excluded. Effect sizes were extracted from the papers and if they were not included in the published papers effect sizes were calculated if possible. No attempt was made to contact authors for missing data.

Results

We found seven reports (six of which used a neurosis diagnosis and one which used a symptom scale). Using Fisher's method we found an increase in mortality which was not significant (p = 0.08).

Conclusion

There have been few studies, and the evidence is weakly in favour of an increased mortality risk. Copyright © 2004 John Wiley & Sons, Ltd.
The criterion validity of the Center for Epidemiological Studies Depression Scale (CES‐D) in a sample of self‐referred elders with depressive symptomatology
Authors: Haringsma R. , Engels G. I. , Beekman A. T. F. , Spinhoven Ph.
Published: May 2004

Background

The criterion validity of the Center for Epidemiological Studies Depression scale (CES‐D) was assessed in a group of elderly Dutch community‐residents who were self‐referred to a prevention program for depression.

Methods

Paper‐and‐pencil administration of the CES‐D to 318 elders (55–85 years). Criterion validity was evaluated with the Mini International Neuropsychiatric Interview (MINI), a clinical diagnostic interview based on DSM‐IV. Sensitivity and specificity for various cut‐off scores of CES‐D were compared with the DSM‐IV major depressive disorder (MDD) and with clinically relevant depression (CRD), a composite diagnosis of MDD, subthreshold depression or dysthymia. Furthermore the characteristics of true versus false positives were analyzed.

Results

For MDD, the optimal cut‐off score was 25, (sensitivity 85%, specificity 64%, and positive predicted value of 63%). For CRD, the optimal cut‐off was 22 (sensitivity 84%, specificity 60%, and positive predicted value 77%). True positives, MDD and CRD, reported significantly more anxiety symptomatology and more co‐morbid anxiety disorders, false positives reported more previous depressive episodes.

Conclusions

The criterion validity of the CES‐D for MDD and CRD was satisfactory in this semi‐clinical sample of elders. Subjects scoring ≥25 constitute a target group for further diagnostic assessment in order to determine appropriate treatment. Copyright © 2004 John Wiley & Sons, Ltd.
The CT‐based radial width of the temporal horn: pathological validation in AD without cerebrovascular disease
Authors: Rossi R. , Joachim C. , Smith A. D. , Frisoni G. B.
Published: May 2004

Background

Medial temporal lobe atrophy is one of the most accurate markers of Alzheimer's disease (AD). Given the wide availability of the CT in the routine diagnostic assessment of patients with cognitive disturbances, a CT‐based marker of AD might be clinically useful.

Objective

To test the accuracy of a simple CT‐based measure, the radial width of the temporal horn (rWTH).

Method

The rWTH was taken in a group of 20 pathologically confirmed AD patients and 23 non demented persons enrolled in the Oxford Project to Investigate Memory and Aging (OPTIMA project).

Results

The rWTH was significantly larger in AD patients than controls. Using a cutoff value between 3.9 at 50 and 8.1 at 90 years, the rWTH was able to correctly classify 16/20 and 19/23 subjects with a sensitivity and a specificity of 80% and 83%. The overall accuracy was 81%.

Conclusion

The CT measurement of the rWTH is a simple and reasonably sensitive marker of regional brain atrophy in AD. Copyright © 2004 John Wiley & Sons, Ltd.
Critical Flicker Fusion Threshold in patients with Alzheimer's disease and vascular dementia
Authors: Curran Stephen , Wilson Simon , Musa Shabir , Wattis John
Published: May 2004

Background

Critical Flicker Fusion Threshold (CFFT) is a psychophysical threshold and in psychological terms is regarded as a measure of information processing capacity. The test has previously been shown to be a valid and reliable measure of CNS functioning in patients with Alzheimer's disease and may be a useful as a screening measure for the early detection of Alzheimer's disease (AD).

Methods

Consecutive referrals to the Wakefield Memory Clinic who met DSM‐IV criteria for AD or vascular dementia (VaD) were invited to take part in the study. A range of neuropsychological tests and CFFT were administered to the two groups using standardised protocols and the ability of these various tests to distinguish between the two conditions was investigated.

Results

Forty‐six patients were included in the study. Of the various tests, only the descending component of CFFT and word fluency were significantly different in the two groups. In addition, the descending threshold had a sensitivity of 83% and a specificity of 69%.

Conclusion

CFFT could be useful as a screening instrument for early AD when combined with other measures and could facilitate the decision to commence antidementia treatment at an early stage. Further longitudinal work is needed to establish this. Copyright © 2004 John Wiley & Sons, Ltd.
Social factors and depression in carers of people with dementia
Authors: Waite Allyson , Bebbington Paul , Skelton‐Robinson Martin , Orrell Martin
Published: May 2004

Background

Research has highlighted the influence of psychosocial factors on the wellbeing of carers of people with dementia. This study aimed to investigate the interrelationships between life events, depression and social support in carers of people with dementia.

Method

Participants were 72 carers of people with dementia. They were interviewed using the Bedford College Life Events and Difficulties Schedule and the Geriatric Depression Scale.

Results

The results showed that 31 (43%) of carers were depressed. Factors associated with depression in carers were a lack of confiding relationship, depression in the person with dementia, and living with the person with dementia.

Conclusions

Carers of people with dementia appear more vulnerable to depression in the context of the caring experience rather than threatening life events. Copyright © 2004 John Wiley & Sons, Ltd.
Reliability of brain volumes from multicenter MRI acquisition: A calibration study
Authors: Schnack Hugo G. , van Haren Neeltje E.M. , Hulshoff Pol Hilleke E. , Picchioni Marco , Weisbrod Matthias , Sauer Heinrich , Cannon Tyrone , Huttunen Matti , Murray Robin , Kahn René S.
Published: May 2004

Multicenter studies can provide additional information over single center studies because of their increased statistical power. Because similar acquisition protocols are being used internationally for structural magnetic resonance imaging (MRI) studies of the human brain, volumetric MRI data studies seem suitable for this purpose. Possible systematic differences between sites should be avoided, however, particularly when subtle differences in tissue volume are being searched for, such as in neuropsychiatric diseases. In this calibration study, the brains of six healthy volunteers were (re)scanned with MR scanners from four different manufacturers at five different sites, using the local acquisition protocols. The images were segmented at a central reference site. The intraclass correlation coefficient (ICC) was determined for the whole brain, gray and white matter, cerebellum, and lateral and third ventricle volumes. When required, the processing algorithms were calibrated for each site. Calibration of the histogram analysis was needed for segmentation of total brain volume at one site and for gray and white matter volume at all sites. No (additional) calibration was needed for cerebellum and ventricle volumes. The ICCs were ≥0.96 for total brain, ≥0.92 for cerebellum, ≥0.96 for lateral ventricle, ≥0.21 for third ventricle, ≥0.84 for gray matter, and ≥0.78 for white matter volume. Calibration of segmentation procedures allows morphologic MRI data acquired at different research sites to be combined reliably in multicenter studies. Hum. Brain Mapping 22:312–320, 2004. © 2004 Wiley‐Liss, Inc.
Aging and aggregate costs of medical care: conceptual and policy issues
Authors: Chernichovsky Dov , Markowitz Sara
Published: May 2004

The conventional wisdom says that because the cost of health care for the aged is more than that of the young at any time, there is a positive relationship between the aging or higher life expectancy of the population and aggregate health care spending. It is difficult, however, to find evidence to support this argument. We present a simple framework that shows how aging of the population may not necessarily increase the total cost of medical care over time or be observed across nations. This follows because numerous other factors that change with aging affect cost of care in ways that are not age‐neutral. Such factors include age‐specific shifts in morbidity and mortality, growth in income and insurance coverage, rising levels of education and changing technology. Consequently, the relative medical costs of the aged may indeed increase, at least for demographic reasons. Simultaneously, however, the costs of the young may decrease for the same reasons. The Israeli experience, used as a basis for a cursory empirical discussion of the issues, supports the line of reasoning presented in the paper. Copyright © 2003 John Wiley & Sons, Ltd.
Using stated preference and revealed preference modeling to evaluate prescribing decisions
Authors: Mark Tami L. , Swait Joffre
Published: May 2004

The use of stated preference analyses to evaluate choice of health care products has been growing in recent years. This paper shows how revealed preference data can be enriched with stated preference data and highlights the relative advantages of revealed and stated preference data. The techniques were applied to a study of determinants of physicians' prescriptions of alcoholism medications. Analyses were conducted on the relationship between physicians' perceptions of existing alcoholism medication attributes and their prescribing rates of those medications. Analyses were also conducted on physicians' decisions to prescribe hypothetical alcoholism medications with varying attributes such as efficacy, side effects, compliance, mode of action, and price. Finally, analyses were conducted on the combined stated and revealed preference data. Joint estimation suggests that parameters from the revealed and stated preference data are equal, up to scale. Joint analyses highlight how stated preference data can be used to estimate parameters for attributes that are not observed in the marketplace, that do not vary in the marketplace, or that are highly collinear with other attributes in actual markets. Copyright © 2003 John Wiley & Sons, Ltd.
Price discrimination in obstetric services – a case study in Bangladesh
Authors: Amin Mohammad , Hanson Kara , Mills Anne
Published: May 2004

This article examines the existence of price discrimination for obstetric services in two private hospitals in Bangladesh, and considers the welfare consequences of such discrimination, i.e. whether or not price discrimination benefited the poorer users. Data on 1212 normal and caesarean section patients discharged from the two hospitals were obtained. Obstetric services were chosen because they are relatively standardised and the patient population is relatively homogeneous, so minimising the scope and scale of product differentiation due to procedure and case‐mix differences. The differences between the hospital list price for delivery and actual prices paid by patients were calculated to determine the average rate of discount. The welfare consequences of price discrimination were assessed by testing the differences in mean prices paid by patients from three income groups: low, middle and high. The results suggest that two different forms of price discrimination for obstetric services occurred in both these hospitals. First, there was price discrimination according to income, with the poorer users benefiting from a higher discount rate than richer ones; and second, there was price discrimination according to social status, with three high status occupational groups (doctors, senior government officials, and large businessmen) having the highest probability of receiving some level of discount. Copyright © 2003 John Wiley & Sons, Ltd.
How property rights and patents affect antibiotic resistance
Authors: Horowitz John B. , Moehring H. Brian
Published: May 2004

Antibiotic resistance tends to increase when a patent on an antibiotic expires. Since other companies can now sell the antibiotic, more of the antibiotic is produced and prices fall. Because the benefits of reducing current production go to other firms, pharmaceutical companies will have little concern about future resistance. This ‘open‐access’ problem causes excessive antibiotic use and resistance problems in the future. Extending patents is one solution. However, a pharmaceutical company that has patent protection on a drug that is cross‐resistant may have little concern about future resistance. This is because when people use completely different antibiotics which cause bacteria to become resistant to the original antibiotic, then the benefits of reducing current production go to other companies. A single buyer such as national health insurance or private health insurance may also have an incentive to reduce antibiotic resistance since they bear the future cost of future resistance. However, insurance coverage reduces the price that patients pay at the margin and thus the patients are likely to use more antibiotics. National health insurance policies may even set the price of antibiotics so low that resistance problems are created even when the patent is in effect. Copyright © 2004 John Wiley & Sons, Ltd.
Resistance‐induced antibiotic substitution
Authors: Howard David H.
Published: May 2004

In many cases, physicians prescribe antibiotics without knowing whether an individual patient is infected with a susceptible or resistant pathogen. As the proportion of resistant organisms in a community increases, physicians substitute away from older‐inexpensive drugs to newer, more expensive agents as first line therapy. This paper explores the implications of resistance‐induced antibiotic substitution for epidemiological models to predict future resistance levels, efforts to measure the health care costs associated with resistance, and policies to improve physicians' antibiotic prescribing decisions. The extent of resistance‐induced substitution in outpatient settings is documented using a data set consisting of observations on initial physician office visits for otitis media in the US controlling for new product introductions and price increases, per prescription antibiotic spending increased by 22% between 1980 and 1996, corresponding to a steep increase in resistance levels over the same period. Copyright © 2004 John Wiley & Sons, Ltd.
Evaporation performance of a new plate‐type heat exchanger with winding tubes on plate surfaces (estimation of performance of the heat exchanger)
Authors: Matsushima Hitoshi , Uchida Mari
Published: May 2004

A method for evaluating and predicting the performance of a newly developed plate‐type heat exchanger as an evaporator for water‐refrigerant systems such as chillers has been developed. The main component of the developed heat exchanger consists of plates packed together in a casing with winding tubes connected to both sides of the plates. Refrigerant flows inside the tubes, and water flows in the space between the plates. A herringbone‐like pattern is formed in this space by the cross sections of the winding tubes. The newly developed method estimates evaporation performance of the developed heat exchanger using new empirical correlations. There are correlations for heat transfer and pressure drop in winding‐tube banks on the water side, and correlation for the pressure drop on the refrigerant side. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(4): 245–257, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20009
Statistical downscaling of daily precipitation from observed and modelled atmospheric fields
Authors: Charles Stephen P. , Bates Bryson C. , Smith Ian N. , Hughes James P.
Published: May 2004

Statistical downscaling techniques have been developed to address the spatial scale disparity between the horizontal computational grids of general circulation models (GCMs), typically 300–500 km, and point‐scale meteorological observations. This has been driven, predominantly, by the need to determine how enhanced greenhouse projections of future climate may impact at regional and local scales. As point‐scale precipitation is a common input to hydrological models, there is a need for techniques that reproduce the characteristics of multi‐site, daily gauge precipitation. This paper investigates the ability of the extended nonhomogeneous hidden Markov model (extended‐NHMM) to reproduce observed interannual and interdecadal precipitation variability when driven by observed and modelled atmospheric fields. Previous studies have shown that the extended‐NHMM can successfully reproduce the at‐site and intersite statistics of daily gauge precipitation, such as the frequency characteristics of wet days, dry‐ and wet‐spell length distributions, amount distributions, and intersite correlations in occurrence and amounts. Here, the extended‐NHMM, as fitted to 1978–92 observed ‘winter’ (May–October) daily precipitation and atmospheric data for 30 rain gauge sites in southwest Western Australia, is driven by atmospheric predictor sets extracted from National Centers for Environmental Prediction–National Center for Atmospheric Research reanalysis data for 1958–98 and an atmospheric GCM hindcast run forced by observed 1955–91 sea‐surface temperatures (SSTs). Downscaling from the reanalysis‐derived predictors reproduces the 1958–98 interannual and interdecadal variability of winter precipitation. Downscaling from the SST‐forced GCM hindcast only reproduces the precipitation probabilities of the recent 1978–91 period, with poor performance for earlier periods attributed to inadequacies in the forcing SST data. Copyright © 2004 John Wiley & Sons, Ltd.
A framework for scaling of hydrologic conceptualizations based on a disaggregation–aggregation approach
Authors: Viney Neil R. , Sivapalan Murugesu
Published: May 2004

A fundamental question in scale research is how to scale up descriptions of hydrological responses from the small scales at which they are developed to the larger scales at which predictions are required or can be validated, in the presence of spatial heterogeneity of soils, vegetation and topography, and of space–time variability of climatic inputs. One scaling approach is the disaggregation–aggregation approach, which involves disaggregating catchment‐scale state variables to point‐scale distributions, applying a suitable point‐scale physical model using these state variables, and aggregating the resulting point‐scale responses to yield a catchment‐scale response. Thus, the approach provides a way of linking the catchment‐scale state variables with the catchment‐scale responses and thereby permits the development of empirical large‐scale models that still retain some essence of the small‐scale physics. In this paper we illustrate the disaggregation–aggregation approach with two examples that deal with developing catchment‐scale conceptualizations of (a) infiltration excess runoff and (b) evapotranspiration, using detailed process‐based models available at the small scale. These conceptualizations became the building blocks of the large‐scale catchment model, LASCAM. Copyright © 2004 John Wiley & Sons, Ltd.
The application of depletion curves for parameterization of subgrid variability of snow
Authors: Luce Charles H. , Tarboton David G.
Published: May 2004

Parameterization of subgrid‐scale variability in snow accumulation and melt is important for improvements in distributed snowmelt modelling. We have taken the approach of using depletion curves that relate fractional snow‐covered area to element‐average snow water equivalent to parameterize the effect of snowpack heterogeneity within a physically based mass and energy balance snowpack model. Comparisons of parameterization outputs with distributed model outputs and observations show performance comparable to the distributed model and reasonable performance relative to observations for time series modelling of snow water equivalent and snow‐covered area. Examination of the relationship between the shapes of the depletion curves and parametric distributions shows that the shapes of dimensionless depletion curves depend primarily on the coefficient of variation and to a lesser extent on the shape of the snow distribution function. The methods presented here are a generalization of several previously used methods to estimate depletion curve shapes. Comparison of several years of observed depletion curves from the study basin show that the shapes of the depletion curves change little from year to year. Copyright © 2004 John Wiley & Sons, Ltd.
Process parameterization and temporal scaling in surface runoff and erosion modelling
Authors: Kandel D. D. , Western A. W. , Grayson R. B. , Turral H. N.
Published: May 2004

It is common for runoff and erosion models to be run at coarse time steps (e.g. daily) owing to limited data availability. However, such models are unable to capture adequately the small‐scale surface runoff and erosion processes that are dominated by, for example, precipitation characteristics at time‐scales of minutes. This dilemma calls for the development of approaches that appropriately capture short time‐scale processes when running the models at daily scales. In this paper, we assess two scaling approaches that are simple and are intended to preserve prediction quality as time scales become coarser: (i) use of effective rates of precipitation and runoff, and (ii) use of a rainfall disaggregation scheme. Runoff and erosion are simulated using a six‐parameter surface runoff model and a one‐parameter erosion model. A downhill simplex optimization algorithm is applied for parameterization at 2 min and daily time steps, using measured 2 min and daily precipitation data respectively, against measured daily runoff and erosion. The 2 min simulation results are aggregated to daily values to make comparisons with the measured plot‐scale daily runoff and erosion data for 2 years (1997–98) from six sites in the Jhikhu Khola catchment in Nepal. The runoff and erosion simulation results calibrated from the 2 min precipitation data are good (E = 0·92 for runoff and 0·80 for erosion, all sites collectively), whereas other results, particularly the erosion simulation from the calibrated daily model, are very poor. These results are taken as the reference to compare with the two different scaling approaches. The effective rate approach is poor compared with the 2 min estimates but is a considerable improvement over daily erosion estimates. The rainfall disaggregation scheme is comparable to the 2 min estimates and produces better results than the effective rate approach. This study illustrates that rainfall scaling has significant scope for temporal scaling of hydrologic processes, particularly where continuous simulation is preferred. Copyright © 2004 John Wiley & Sons, Ltd.
Exploring streamflow response to effective rainfall across event magnitude scale
Authors: Kokkonen Teemu , Koivusalo Harri , Karvonen Tuomo , Croke Barry , Jakeman Anthony
Published: May 2004

Sets of flow events from four catchments were selected in order to study how dynamics in the conversion of effective rainfall into streamflow depends on the event size. The approach taken was to optimize parameters of a linear delay function and effective rainfall series concurrently from precipitation–streamflow data without imposing a functional form of the precipitation filter a priori. The delay function is an instantaneous unit hydrograph (IUH) having a mathematical form of the two‐parameter gamma distribution. Results from two small research catchments (0·18 and 0·63 km2) with sub‐daily data suggest a clear relationship between the event magnitude and response dynamics. The effect of the sampling frequency of data was addressed by gradually increasing aggregation interval of rainfall and flow data and repeating the optimization for each aggregated dataset. IUHs for different data aggregation intervals (for a single event) tended to be similar unless the aggregation changed the locations of data peaks. IUHs identified in larger catchments (58 and 1235 km2) also showed variability through events; however, no systematic event magnitude dependence, as was visible in the small research catchments, was detected. Finally, the dependency detected in the small catchments was exploited in a rainfall‐runoff model, where the scale parameter of the gamma distribution was linearly related to the effective rainfall intensity. Prediction of peak flows improved when the event dependency was taken into account. Copyright © 2004 John Wiley & Sons, Ltd.
Low‐dimensional modelling of numerical groundwater flow
Authors: Vermeulen P. T. M. , Heemink A. W. , te Stroet C. B. M.
Published: May 2004

Numerical models are often used for simulating groundwater flow. Written in state‐space form, the dimension of these models is of the order of the number of grid cells used and can be very high (more than a million). As a result, these models are computationally very demanding, especially if many different scenarios have to be simulated. In this paper we introduce a model reduction approach to develop an approximate model with a significantly reduced dimension. The reduction method is based upon several simulations of the large‐scale numerical model. By computing the covariance matrix of the model results, we obtain insight into the variability of the model behaviour. Moreover, by selecting the leading eigenvectors of this covariance matrix, we obtain the spatial patterns that represent the directions in state space where the model variability is dominant. These patterns are also called empirical orthogonal functions. We can project the original numerical model onto those dominant spatial patterns. The result is a low‐dimensional model that is still able to reproduce the dominant model behaviour. Copyright © 2004 John Wiley & Sons, Ltd.
Body size and breast cancer risk: Findings from the European prospective investigation into cancer and nutrition (EPIC)
Authors: Lahmann Petra H. , Hoffmann Kurt , Allen Naomi , van Gils Carla H. , Khaw Kay‐Tee , Tehard Bertrand , Berrino Franco , Tjønneland Anne , Bigaard Janne , Olsen Anja , Overvad Kim , Clavel‐Chapelon Françoise , Nagel Gabriele , Boeing Heiner , Trichopoulos Dimitrios , Economou George , Bellos George , Palli Domenico , Tumino Rosario , Panico Salvatore , Sacerdote Carlotta , Krogh Vittorio , Peeters Petra H.M. , Bueno‐de‐Mesquita H. Bas , Lund Eiliv , Ardanaz Eva , Amiano Pilar , Pera Guillem , Quirós José R. , Martínez Carmen , Tormo María J. , Wirfält Elisabet , Berglund Göran , Hallmans Göran , Key Timothy J. , Reeves Gillian , Bingham Sheila , Norat Teresa , Biessy Carine , Kaaks Rudolf , Riboli Elio
Published: May 2004

The evidence for anthropometric factors influencing breast cancer risk is accumulating, but uncertainties remain concerning the role of fat distribution and potential effect modifiers. We used data from 73,542 premenopausal and 103,344 postmenopausal women from 9 European countries, taking part in the EPIC study. RRs from Cox regression models were calculated, using measured height, weight, BMI and waist and hip circumferences; categorized by cohort‐wide quintiles; and expressed as continuous variables, adjusted for study center, age and other risk factors. During 4.7 years of follow‐up, 1,879 incident invasive breast cancers were identified. In postmenopausal women, current HRT modified the body size–breast cancer association. Among nonusers, weight, BMI and hip circumference were positively associated with breast cancer risk (all ptrend ≤ 0.002); obese women (BMI > 30) had a 31% excess risk compared to women with BMI < 25. Among HRT users, body measures were inversely but nonsignificantly associated with breast cancer. Excess breast cancer risk with HRT was particularly evident among lean women. Pooled RRs per height increment of 5 cm were 1.05 (95% CI 1.00–1.16) in premenopausal and 1.10 (95% CI 1.05–1.16) in postmenopausal women. Among premenopausal women, hip circumference was the only other measure significantly related to breast cancer (ptrend = 0.03), after accounting for BMI. In postmenopausal women not taking exogenous hormones, general obesity is a significant predictor of breast cancer, while abdominal fat assessed as waist–hip ratio or waist circumference was not related to excess risk when adjusted for BMI. Among premenopausal women, weight and BMI showed nonsignificant inverse associations with breast cancer. © 2004 Wiley‐Liss, Inc.
Keeping off the grass? An econometric model of cannabis consumption in Britain
Authors: Pudney Stephen
Published: May 2004

This paper presents estimates of a dynamic individual‐level model of cannabis consumption, using data from a 1998 survey of young people in Britain. The econometric model is a split‐population generalization of the non‐stationary Poisson process, allowing for separate dynamic process for initiation into cannabis use and subsequent consumption. The model allows for heterogeneity in consumption levels and behavioural shifts induced by leaving education and the parental home. Copyright © 2004 John Wiley & Sons, Ltd.
Dynamics of the federal funds target rate: a nonstationary discrete choice approach
Authors: Hu Ling , Phillips Peter C. B.
Published: May 2004

We apply a discrete choice approach to model the empirical behaviour of the Federal Reserve in changing the federal funds target rate, the benchmark of short‐term market interest rates in the US. Our methods allow the explanatory variables to be nonstationary as well as stationary. This feature is particularly useful in the present application as many economic fundamentals that are monitored by the Fed and are believed to affect decisions to adjust interest rate targets display some nonstationarity over time. The chosen model successfully predicts the majority of the target rate changes during the time period considered (1994–2001) and helps to explain strings of similar intervention decisions by the Fed. Based on the model‐implied optimal interest rate, our findings suggest that there is a lag in the Fed's reaction to economic shocks during this period. Copyright © 2004 John Wiley & Sons, Ltd.
Making inferences about the polarization, welfare and poverty of nations: a study of 101 countries 1970–1995
Authors: Anderson Gordon
Published: May 2004

Stochastic Dominance techniques are adapted and employed to study the extent and progress of Polarization, Welfare and Poverty of 101 nations over the period 1970–1995. The adaptations provide methods of comparing mass relocation by evaluating various degrees of right and left separation between distributions. The results reveal that, whilst welfare increased and then diminished and poverty diminished and then increased, polarization between rich and poor countries continued unabated throughout the period emphasizing the distinction between polarization and inequality. Copyright © 2004 John Wiley & Sons, Ltd.
Social security, pensions and retirement behaviour within the family
Authors: Gustman Alan L. , Steinmeier Thomas L.
Published: May 2004

This paper estimates a structural model of family retirement using US data from the Health and Retirement Study (HRS). It provides further insight into household retirement decision making and the reasons for interdependence in the retirement decisions of each spouse. Improvements in HRS data and matched employer provided pension histories allow more precise identification of key parameters governing interdependent behaviour within the household.

In an earlier study we found that interdependence was due to preferences rather than coordination of retirement incentives in the budget, and in particular that it is not a correlation in preferences, but the appearance of the spouse's retirement status in the husband's and wife's utility function that is largely responsible for coordination of retirement between spouses. We now find that a measure of how much each spouse values being able to spend time in retirement with the other accounts for a good portion of that apparent interdependence. For the wife, the husband's retirement status influences her retirement decision only if she values spending time in retirement with her husband. For husbands, the effect of having the wife already retired on his retirement decision is roughly doubled if he enjoys spending time in retirement with his wife, but there is some effect even if he does not. This is consistent with our earlier findings that the husband is more influenced by having a retired spouse than the wife is. The increase in the extent of the dependence of the wife's labour supply on the husband's retirement from our past work probably is traceable to better measurement of the opportunity set facing the husband in HRS data.

Once estimated, we use the model to investigate the labour supply effects of alternative social security policies, examining the effect of dividing credit for earnings evenly between spouses, or of basing social security benefits on the amounts accumulated in private accounts. Both policies change the relative importance of spouse and survivor social security benefits within the household and both raise the relative reward to work later in the life cycle. The incentives created are modest, and retirement responds accordingly. Nevertheless, at some ages, such as 65, there may be as much as a 6% increase in the old age work force under privatized accounts. Copyright © 2004 John Wiley & Sons, Ltd.
In vivo evaluation of a novel electrically conductive polypyrrole/poly(D,L‐lactide) composite and polypyrrole‐coated poly(D,L‐lactide‐co‐glycolide) membranes
Authors: Wang Zhaoxu , Roberge Christophe , Dao Lê H. , Wan Ying , Shi Guixin , Rouabhia Mahmoud , Guidoin Robert , Zhang Ze
Published: May 2004

This study evaluated the in vivo biocompatibility and biodegradation behavior of a novel polypyrrole (PPy)/poly(D,L‐lactide) (PDLLA) composite and PPy‐coated poly(D,L‐lactide‐co‐glycolide) membranes. Test membranes were implanted subcutaneously in rats for 3–120 days. The biocompatibility was assessed by quantifying the alkaline and acid phosphatase secretion, the immunohistochemical staining of the ED‐2‐positive macrophages, and the histology at the tissue/material interface. The degradation was investigated using scanning electron microscopy. Pure PDLLA and poly(D,L‐lactide‐co‐glycolide) membranes were used as references, whereas expanded polytetrafluoroethylene and a commercial styrene‐butadiene rubber were used as controls. The enzyme activity of the PPy‐containing specimens was shown to be similar to that of the references. The histological findings were consistent with the enzymatic results, showing a mild‐to‐moderate acute inflammation followed by a resolution of the inflammatory response with a decrease in inflammatory cells for each biodegradable membrane. The tissue reactions to the PPy, which was either in the form of nanoparticles or surface coating, were comparable to the response to the neighboring biodegradable materials. Elevated ED‐2‐positive macrophage populations appeared as early as day 3 in the loose connective tissue surrounding the implants. The density of these populations was related to the degree of inflammation. Scanning electron microscopy showed that the degradation of the PPy/PDLLA composite was not affected by the presence of PPy. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 70A: 28–38, 2004