bluuebunny/crossref_metadata_2025 huggingface dataset:
Treefall gap size effects on above‐ and below‐ground processes in a tropical wet forest
Authors: Denslow Julie S. , Ellison Aaron M. , Sanford Robert E.
Published: May 2003

1We examined the effects of variation in gap size on above‐ and below‐ground light and nutrient processes in a tropical wet forest in Costa Rica.

2Trees were felled to create canopy openings ranging in size from 65 to 611 m2. Following treefall, we measured initial litter mass in the crown zone of six gaps. During the subsequent year, we measured litter decomposition rate and light levels as well as NH4‐N, NO3‐N and PO4‐P levels in surface soils, soil moisture and fine root mass. We also measured growth rates of fertilized and non‐fertilized plants of four species ofMiconia(Melastomataceae) to assess nutrient limitation to plant growth in large gaps.

3Light levels in the centres of gaps were significantly related to size of the canopy opening. After 1 year, light levels near the ground in larger openings (35–40% full sunlight immediately after treefall) declined to levels similar to those in smaller gaps (10–20%).

4Although canopy opening had only slight effects on soil NH4‐N, NO3‐N pools were significantly greater in gaps than in understorey at both sites. The effect was positively correlated with gap size. Extractable PO4‐P was also greater in gaps than in adjacent understorey, although the difference did not vary as a function of gap size. In three of six gaps, fine root biomass was less in gaps than in adjacent understorey.

5Of four species ofMiconia, onlyM. affinis, a small tree common in early secondary forests, grew significantly faster in fertilized than in non‐fertilized treatments in three large gaps.

6Our data suggest that higher nutrient pools in surface soils of treefall gaps may result from decomposition and mineralization of the large mass of fresh litter from the fallen tree. While growth rates of shade‐tolerant rain forest trees and shrubs are not much affected by the increased nutrient availability even at high light levels, growth rates of pioneer or high‐light demanding species may be enhanced by increased above‐ and below‐ground resources.
A 38‐year study of relations between weather and vegetation dynamics in road verges near Bibury, Gloucestershire
Authors: Dunnett N. P. , Willis A. J. , Hunt R. , Grime J. P.
Published: May 2003

1 The Bibury long‐term data set contains information on annual fluctuations in the abundance of over 100 grasses and forbs in roadside verge vegetation over the period from 1958 to the present. Monitoring has been carried out every July by the same individual. The data set represents a unique long‐term record of the dynamics of a complete plant community.

2 Records for the most abundant taxa (including bare ground and litter) were used to determine the effect of climate variability on the year‐to‐year performance of the selected species. Residuals about the long‐term mean log biomass of each species (de‐trended where the species showed a significant increase or decrease in abundance over time) were correlated against indices of interannual climate variability. Plant and weather records were compared over 3‐month seasonal periods (March–May, June–August, September–November, December–February) or 6‐month seasonal periods (March–August, September–February), with time lags of 0, 1 and 2 years.

3 Principal components analysis (PCA) was used to formulate annual weather indices, using either conventional weather variables (temperature, rainfall and sunshine) or the Lamb catalogue of daily weather types.

4 Between 5% and 70% more correlations were observed than might be expected to occur by chance, depending on the season and the PCA index, indicating markedly non‐random plant–weather relationships. Total vegetation production was positively correlated with minimum spring temperature. The distribution of correlations was generally evenly distributed across the three lag periods.

5 In general, those species favoured by environmental stress or disturbance were promoted following warm dry springs and summers, whereas those favoured by more productive conditions were promoted following a wet growing season.
Seed dispersal, seedling establishment and gap partitioning among tropical pioneer trees
Authors: Dalling J. W. , Hubbell Stephen P. , Silvera Katia
Published: May 2003

1 We examined the abundance and distribution patterns of pioneer seeds in the soil seed bank, and of pioneer seedlings in 53 recently formed gaps, in a 50‐ha forest dynamics plot on Barro Colorado Island (BCI), Panama. The aim was to assess the importance of dispersal limitation (failure of seeds to arrive at all sites suitable for their germination) and establishment limitation (failure of seeds having reached a site to germinate successfully and establish as seedlings) in determining patterns of gap occupancy.

2 The abundance of seeds in the soil seed bank was strongly negatively correlated with seed size, but was not correlated with the abundance of reproductive‐sized adult trees in the plot. In contrast, the abundance of pioneer seedlings > 10 cm height in natural gaps was strongly correlated with adult abundance, but was not correlated with seed size.

3 Seedlings were non‐randomly distributed among gaps, but seedling abundance was not directly related to gap size, and there was no evidence of partitioning of the light environment of gaps by small seedlings. Large differences in growth and mortality rates among species were observed after 1 year, and this may result in the gap size partitioning previously found in saplings of the same species.

4 Seedlings of most species, particularly those with large seeds, were relatively more abundant than expected in gaps close to their conspecific adults. Proximity to reproductives, and by inference dispersal limitation, therefore exerts some effect on seedling distribution. None the less, large differences between seed and seedling abundances for some species, and low seedling occupancy rates in some gaps close to adult conspecifics, suggest that seedling emergence probabilities and species‐specific establishment requirements may also be important determinants of local abundance.
Comparative ecology of 11 sympatric species of Macaranga in Borneo: tree distribution in relation to horizontal and vertical resource heterogeneity
Authors: Davies Stuart James , Palmiotto Peter A. , Ashton Peter S. , Lee Hua Seng , Lafrankie James V.
Published: May 2003

1 Horizontal and vertical heterogeneity of resource availability, coupled with the specialized use of resources by tree species, results in complex patterns of tree species distributions in tropical rain forests. We studied the horizontal and vertical distributions of 4014 individuals in 11 species of early successional Macaranga (Euphorbiaceae) in tropical rain forest in Sarawak, Malaysia.

2 The horizontal distribution of individual trees was assessed with respect to crown light levels, establishment microsites, and broader scale variation in soil textural properties. Vertical distribution was assessed using an allometric approach to estimate maximum tree height (Hmax) and the slope of the sapling height–diameter relationship.

3 Average light levels intercepted and the proportion of individuals in each of five crown illumination classes varied significantly among the 11 species. Species ranged from extremely high‐light demanding, to quite shade tolerant. Average light levels intercepted by trees generally increased through ontogeny, but the ranking of species did not change significantly.

4 Fewer individuals of the more shade‐tolerant species established on disturbed microsites, irrespective of light levels. Among the more high‐light demanding species, the proportion of trees on different types of disturbed sites varied.

5 Trees of seven species were significantly more common on clay‐rich soils, two preferred sand‐rich soils, and two were not strongly affected by soil texture.

6 Hmax ranged from 5.5 to 31.3 m and was negatively correlated with shade tolerance among species, although among the more high‐light demanding species there was a wide range of tree sizes. Among species, Hmax was negatively correlated with both the slope and y‐intercept of the sapling height–diameter relationship, indicating that small‐statured species (also more shade tolerant) had more slender saplings than larger statured species.

7 Heterogeneity of resource availability leads to differences in horizontal and vertical tree distribution, which are important for the coexistence of 11 Macaranga species.
The effects of air‐borne nitrogen pollutants on species diversity in natural and semi‐natural European vegetation
Authors: Bobbink Roland , Hornung Michael , Roelofs Jan G. M.
Published: May 2003

The effects of increased atmospheric nitrogen inputs, from both NOy and NHx, on diversity in various semi‐natural and natural ecosystems are reviewed. The severity of these impacts depends on abiotic conditions (e.g. buffering capacity, soil nutrient status and soil factors that influence the nitrification potential and nitrogen immobilization rate) in the particular system. The sensitivity of fresh water ecosystems, wetlands and bogs, species‐rich grasslands, heathlands and field layer of forests, all of which have conservational value, are discussed in detail.

The most important effects of nitrogen deposition are: (i) accumulation of nitrogenous compounds resulting in enhanced availability of nitrate or ammonium; (ii) soil‐mediated effects of acidification; and (iii) increased susceptibility to secondary stress factors.

Long‐term nitrogen enrichment has gradually increased the availability of nitrogen in several vegetation types, leading to competitive exclusion of characteristic species by more nitrophilic plants, especially under oligo‐ to mesotrophic soil conditions.

Soil acidification (with losses of buffering capacity and increased concentrations of toxic metals) is especially important after nitrification of ammonium in weakly buffered environments: acid‐resistant plant species then become dominant at the expense of the often rare plants typical of intermediate pH. The related change in the balance between ammonium and nitrate may also affect the performance of several species.

The susceptibility of plant species to secondary stress factors (pathogens; frost and drought) may be affected by air‐borne nitrogen but data are only available for a few communities (e.g. dry heathlands).

Most global biodiversity is contained within natural and semi‐natural vegetation. It is thus crucial to control emissions of nitrogenous compounds to the atmosphere, in order to reduce or prevent effects on diversity in these systems. Most research has focused on acidification in forestry stands and lakes and on the effects on trees. We highlight serious gaps in knowledge of other ecosystems.
Modelling the impact of small‐scale heterogeneities on tree—grass coexistence in semi‐arid savannas
Authors: Jeltsch F. , Milton S.J. , Dean W.R.J. , van Rooyen N. , Moloney K.A.
Published: May 2003

Savanna ecosystems show codominance of trees and grasses, and the mechanisms involved in their coexistence remain unresolved. We investigated the possible influence of small‐scale heterogeneities and disturbances in determining tree spacing and tree‐grass coexistence in semi‐arid savannas, using a spatially explicit, grid‐based simulation model.

We added factors such as seed clumping, locally improved moisture conditions, vegetation clearing and combinations of all three of these variables to a previously published model. We also examined the influence of changing the size and spatiotemporal correlation among individual heterogeneities.

Increased seed availability in localized clumps, especially in combination with the other heterogeneity types, had the strongest impact on the long‐term tree‐grass coexistence in the model. Localized deposition of tree seeds in herbivore dung and underground seed caches built by seed‐collecting rodents may act as a determinant of the distribution of trees in savannas.

Spatially autocorrelated small‐scale heterogeneities led to a more stable coexistence of trees and grasses than uncorrelated heterogeneities did, and at high levels of autocorrelation runs with all three variables led to long‐term coexistence in up to 60% of the rainfall scenarios tested.

The size of individual heterogeneities, also played a significant role in determining whether trees would establish as lone individuals or in clumps. In simulations that included small‐scale heterogeneities, the number of isolated trees scattered throughout the landscape increased, whereas large heterogeneity patches and high spatiotemporal autocorrelation tended to promote tree clustering.

Simulations based on rainfall data from the southern Kalahari produced a realistic density and spatial distribution for trees in this semi‐arid savanna for a realistic range of small‐scale heterogeneities.

Small‐scale disturbances and heterogeneities, at least those that furnish better establishment conditions for tree seedlings, therefore act to increase the range of environmental conditions under which trees and grasses can coexist as savanna.
Effects of nitrogen addition on successional dynamics and species diversity in Michigan old‐fields
Authors: Huberty Lisa E. , Gross Katherine L. , Miller Carolyn J.
Published: May 2003

We examined the impact of nitrogen addition on early successional dynamics and plant species diversity in replicate plots of an old‐field succession treatment in south‐western Michigan, USA, for 7 years following abandonment from agriculture.

Nitrogen addition significantly increased above‐ground plant biomass, but had no effect on the displacement or persistence of different life‐history groups. Annual species made up a similar proportion of community biomass and decreased at equivalent rates in control and nitrogen‐addition microplots. Perennial species biomass increased at similar rates in the control and nitrogen‐addition microplots.

Annual species dominated initially, but declined in abundance over the first 4 years and were replaced by biennials and then herbaceous perennials. The resulting high numbers of species losses and gains were not affected by nitrogen addition.

Nitrogen addition did not affect mean species density or the Shannon index of diversity. There was also no temporal change in the similarity of species composition between control and nitrogen‐addition microplots, indicating that nitrogen addition did not cause divergence over time in community composition. In year 7, similar species dominated the nitrogen‐addition and control microplots, but there were differences in species composition and abundance of the subordinate species in each community.

Only in year 6 of this study was there a significant negative relationship between community biomass and the Shannon diversity index. There was no significant relationship between community biomass and species density in any of the first 7 years following abandonment. Thus, the community response to increased biomass due to nitrogen addition was expressed primarily through changes in community structure, not richness.

The effects of nitrogen addition on the early successional dynamics, species composition and consequently diversity of a plant community may depend on initial site conditions. The response to nitrogen enrichment may be slower in sites such as ours with fertile soils that become dominated by herbaceous perennial dicots.
Fire and vegetation dynamics in a jack pine and black spruce forest reconstructed using fossil pollen and charcoal
Authors: Larsen C.P.S. , Macdonald G.M.
Published: May 2003

Fire and vegetation dynamics in a boreal Pinus banksiana and Picea mariana forest are reconstructed using a 580 year fossil pollen and charcoal record obtained from 128 contiguous samples, each representing c. 4.55 years of sediment.

The general post‐fire vegetation changes, as indicated by cross‐correlation analyses, are an increase in ground layer taxa and shrubs, followed by an increase in coniferous trees and Betula papyrifera. The size and exact timing of the peak abundance in each taxon differs after individual fires.

Sixteen fires are identified using pollen and charcoal records. The mean fire interval is 34 years, similar to fire cycle estimates of 38 and 39 years from dendrochronological studies.

On two occasions, Picea mariana appears to replace Pinus banksiana as the local dominant, each time taking less than 70 years.

An unusual decline in Pinus pollen between c. AD 1816 and 1861 corresponds with a similar decline in a pollen record from 50 km WSW of this site. This may have been caused by Little Ice Age cooling.
Demographic and growth responses of a guerrilla and a phalanx perennial grass in competitive mixtures
Authors: Humphrey L. David , Pyke David A.
Published: May 2003

The advantages of guerrilla and phalanx growth for the guerrilla Elymus lanceolatus ssp. lanceolatus and phalanx E. l. ssp. wawawaiensis were evaluated over 2 years in two taxon mixtures with a range of densities of each subspecies and under two levels of watering.

Ramet numbers and biomass of the guerrilla subspecies were higher than those of the phalanx grass in the first year but in the second year declined greatly, while the phalanx grass showed no change in biomass and an increase in ramet numbers. High neighbour densities affected the phalanx subspecies more strongly than the guerrilla subspecies in the first year, but in the second year there were few differences between subspecies. Biomass of the guerrilla grass remained greater than that of the phalanx grass but ramet numbers were similar in the second year.

For both subspecies in both years, probability of flowering decreased at higher neighbour densities, indicating adaptation for competitive ability. In the first year, biomass was more strongly reduced by densities than flowering was, but in the second year, when crowding was apparently greater, flowering was more severely affected.

Genet survival was high and similar for both subspecies.

The presumed advantage of guerrilla subspecies in exploiting open space was supported. The guerrilla grass exploited resources more quickly in the first year by faster growth and greater ramet production, but its biomass, ramet numbers and rhizome growth, and thus its advantage, were reduced in the second year.

The phalanx subspecies had slower growth, produced more ramets in later years, and delayed flowering until later years. Although less able to exploit open resources, it appeared adapted to more stressful conditions, and may be able to exploit temporal resource pulses more effectively.
Pre‐school children with and without developmental delay: behaviour problems and parenting stress over time
Authors: Baker B. L. , McIntyre L. L. , Blacher J. , Crnic K. , Edelbrock C. , Low C.
Published: May 2003

Background  Children with intellectual disability are at heightened risk for behaviour problems and diagnosed mental disorder.

Methods  The present authors studied the early manifestation and continuity of problem behaviours in 205 pre‐school children with and without developmental delays.

Results  Behaviour problems were quite stable over the year from age 36–48 months. Children with developmental delays were rated higher on behaviour problems than their non‐delayed peers, and were three times as likely to score in the clinical range. Mothers and fathers showed high agreement in their rating of child problems, especially in the delayed group. Parenting stress was also higher in the delayed group, but was related to the extent of behaviour problems rather than to the child's developmental delay.

Conclusions  Over time, a transactional model fit the relationship between parenting stress and behaviour problems: high parenting stress contributed to a worsening in child behaviour problems over time, and high child behaviour problems contributed to a worsening in parenting stress. Findings for mothers and fathers were quite similar.
Child behaviour problems and partner mental health as correlates of stress in mothers and fathers of children with autism
Authors: Hastings R. P.
Published: May 2003

Background  Previous research has suggested that the mothers and fathers of children with disabilities experience stress differently. Although there has been a great deal of research exploring how children affect parents, there have been many fewer studies of the interrelationships between mothers’ and fathers’ psychological well‐being.

Methods  Eighteen married couples who were the parents of children with autism reported on their stress and their general mental health (i.e. anxiety and depression). Teachers rated the behaviour problems of the children with autism.

Results  Mothers and fathers did not differ in their levels of stress and depression, but mothers reported more anxiety than fathers. Partial correlation analyses revealed that child behaviour problems and fathers’ mental health were associated with mothers’ stress. However, neither child behaviour problems or mothers’ mental health was associated with fathers’ stress.

Conclusions  Although requiring replication, the results suggest that stress in mothers of children with disabilities may be affected by the psychological health of other family members, whereas fathers’ stress is affected more by other factors. Methodological and conceptual issues, and the practical implications of these results are discussed.
Depression: its trajectory and correlates in mothers rearing children with intellectual disability
Authors: Glidden L. M. , Schoolcraft S. A.
Published: May 2003

Background Rearing a child with an intellectual disability (ID) is a lifelong activity, and research needs to reflect the extended nature of the task as well as its complexity. The present longitudinal study reports on an 11‐year follow‐up of adoptive and birth families rearing children with ID. Its focus was on depressive symptoms and how these changed over time in a sample of 187 mothers. In particular, the authors were interested in whether initial differences in depression between adoptive mothers who knowingly and willingly decided to rear their children with disabilities, and birth mothers for whom the diagnosis of disability was unexpected and frequently crisis‐inducing, would persist over time.

Methods A longitudinal method with three times of measurement provided data which were analysed with analysis of variance and regression techniques. Moreover, several other individual and family adjustment measures were examined with respect to their correlations with depression and an outcome variable that measured subjective well‐being with regard to the child. Furthermore, mothers were classified as typical or atypical for their adoptive/birth group based on their depression scores at the first time of measurement. The authors predicted that later depression would be different based on the earlier scores.

Results Both adoptive and birth mothers reported low depression, not significantly different from each other, at the 11‐year follow‐up. The personality variable of neuroticism was the strongest predictor of depression for both adoptive and birth mothers, accounting for 24% and 23% of the variance, respectively, but it did not predict the mother's subjective well‐being with regard to the child. Mothers classified as typical or atypical for their groups at initial measurement continued to report significantly different depression scores 11 years later.

Conclusions The low depression scores, not significantly different for birth and adoptive mothers, portray the long‐term prognosis for adjustment to rearing children with disabilities as primarily positive. Moreover, the predictive value of neuroticism suggests that general mental health is an important component influencing this adjustment. Nevertheless, a different pattern for a different outcome variable suggests that multiple measures are necessary to portray accurately the complexity of reaction over time.
Stress, social support and well‐being of Arab mothers of children with intellectual disability who are served by welfare services in northern Israel
Authors: Duvdevany I. , Abboud S.
Published: May 2003

Background  The present study examined the influence of a social support system on the level of stress and the sense of personal well‐being of 100 Israeli Arab mothers of young children with special needs.

Methods  Fifty mothers were served by the welfare services in the Nazareth area while 50 did not get help on a regular basis. A comparison was done between educated, urban mothers, and less‐educated, rural mothers.

Results  The research results point to a relationship between informal support resources, and the marital and economic stress of the mothers: the higher the amount of the informal support resources, the lower the level of stress that was experienced by the mothers. A relationship between the amount of informal support and level of parental stress was not confirmed. A relationship between the amount of support resources and the personal well‐being of the mothers was found: the higher the amount of informal support resources, the higher the sense of well‐being of the mothers. A relationship between formal support (the welfare services), and level of stress or personal well‐being was not found. Education and place of living were not related to level of stress or personal well‐being. Educated mothers from urban areas used the formal support (the welfare services) less than less‐educated mothers who lived in rural areas.

Conclusions  The findings are interpreted with respect to practice and previous studies.
Fathers of children with Down's syndrome versus other types of intellectual disability: perceptions, stress and involvement
Authors: Ricci L. A. , Hodapp R. M.
Published: May 2003

Background  The present study examined fathers’ perceptions of, stress relating to and involvement with children with Down's syndrome (DS) (n = 30) versus those with other types of intellectual disability (ID) (n = 20).

Methods  Fathers and mothers completed questionnaires about their children's personalities and maladaptive behaviours, their own parenting stress, and the fathers’ level of involvement.

Results  Both fathers and mothers rated their children with DS as having more positive personality traits and fewer maladaptive behaviours. Possibly because of these positive perceptions, fathers of children with DS also reported less child‐related stress, particularly in the areas of acceptability, adaptability and demandingness. The two groups of fathers were very similarly involved in child rearing. The personality, age and maladaptive behaviours of the children related to stress levels in the fathers of children with DS, while maladaptive behaviours, gender and the fathers’ education levels related to stress levels in the fathers of children with other types of ID.

Conclusions  These results highlight the importance of examining parental stress and involvement with children with different types of ID.
The Family Stress and Coping Interview for families of individuals with developmental disabilities: a lifespan perspective on family adjustment
Authors: Nachshen J. S. , Woodford L. , Minnes P.
Published: May 2003

Background  The present study investigated the psychometric properties of the Family Stress and Coping Interview (FSCI), a questionnaire designed to quantitatively and qualitatively examine the experiences of parents of children with developmental disabilities (DDs).

Methods  The participants consisted of 106 primary caregivers of 106 individuals with DDs from centres in Eastern, Central and North‐western Ontario, Canada. The participants completed a demographic questionnaire, the FSCI, and the Vineland Adaptive Behaviour Scales.

Results  The results of this study indicate that the FSCI has adequate reliability (i.e. internal consistency and long‐term stability) and validity (i.e. independent item ratings and discriminant validity).

Conclusions  The results of this study support the use of the FSCI as a measure of family stress in research and practice.
The Son‐Rise Program1 intervention for autism: an investigation into family experiences
Authors: Williams K. R. , Wishart J. G.
Published: May 2003

Background  Despite the increasing involvement of parents as therapists in interventions for their children with autism, research to date has focused almost exclusively on the outcome for the child, and little is known about the effects of involvement on the whole family. This is true even of highly intensive home‐based approaches such as the Son‐Rise Program (SRP), the focus of the present paper. A longitudinal questionnaire‐based study is reported which investigated a number of potential positive and negative effects for the family, how these changed over time, and their relation to child characteristics and patterns of intervention implementation.

Methods  Questionnaires examining family demographics, patterns of intervention use and perceived family effects were distributed three times over the course of a year to families who had attended an initial training course in the use of the SRP.

Results  The results indicated that, although involvement led to more drawbacks than benefits for the families over time, family stress levels did not rise in all cases. Few relationships were found between family effects and patterns of intervention use, although there was a strong connection with parental perceptions of intervention efficacy.

Conclusions  The findings of the present study emphasize the need for those supporting families using home‐based interventions to consider the needs of the whole family. This may be especially important if there are periods during which the family find the intervention to be less effective. Families embarking on such intensive approaches may also benefit from considering ways in which any disruption to family life can be minimized.
The role of coping in maintaining the psychological well‐being of mothers of adults with intellectual disability and mental illness
Authors: Kim H. W. , Greenberg J. S. , Seltzer M. M. , Krauss M. W.
Published: May 2003

Background  Mothers who have a child with intellectual disability (ID) or mental illness face a lifetime of caregiving responsibilities and challenges. The present study investigated changes over time in how mothers cope with the challenges of caring for an adult child with disabilities and the effects of changes in coping on maternal well‐being.

Methods  A sample of 246 ageing mothers of adults with ID and 74 mothers of adults with mental illness was drawn from two parallel longitudinal studies of later‐life caregiving.

Results  There was considerable variability at the individual level in the degree to which mothers changed over time in their use of problem‐focused and emotion‐focused coping strategies. For both groups, an increase in their use of emotion‐focused coping led to declining levels of well‐being. For the parents of adults with ID, an increase in their use of problem‐focused coping resulted in a reduction in distress and an improvement in the quality of the relationship with their adult child. For the parents of adults with mental illness, an increase in the use of problem‐focused coping had no effect on levels of distress, but led to an improved relationship with their adult child.

Conclusions  The present study underscores the importance of coping in the lives of older mothers of adults with disabilities.
Supporting families over the life course: mapping temporality
Authors: Grant G. , Nolan M. , Keady J.
Published: May 2003

Background  The present paper addresses a rather neglected dimension of family caregiving, its temporality. Many accounts of caregiving assume a state of stasis, and therefore, overlook factors which shape the evolving experience of family caregiving over the life course.

Methods  The paper begins by offering some reflections on theoretical and methodological issues identified by life‐course researchers.

Results  Based both on theoretical propositions and a growing body of empirical evidence, this paper offers a heuristic for thinking about caregiving stages applied to families supporting people with intellectual disability.

Conclusions  This heuristic is used to suggest further avenues of research and development.
Toward assessing family outcomes of service delivery: validation of a family quality of life survey
Authors: Park J. , Hoffman L. , Marquis J. , Turnbull A. P. , Poston D. , Mannan H. , Wang M. , Nelson L. L.
Published: May 2003

Background  The concept of family quality of life (QoL) has emerged as an important outcome of service delivery for individuals with disabilities and their families. The present study describes the process of developing a tool to measure family QoL.

Methods and Results  A total of 1197 respondents participated in a national field test. Through factor analysis, the survey was refined in several ways: (1) the preliminary 10‐domain structure was reduced to a five‐domain structure; (2) a total of 41 items were selected for the revised survey; and (3) wordings were clarified.

Conclusions  The implications for future research and practice are discussed.
Mothers of children and adolescents with intellectual disability: social and economic situation, mental health status, and the self‐assessed social and psychological impact of the child's difficulties
Authors: Emerson E.
Published: May 2003

Background

Few large‐scale studies with well‐constructed samples have compared the socio‐economic circumstances and social impact of raising a child with intellectual disability (ID). The aims of the present paper were to: (1) compare the socio‐economic situation of mothers raising a child with ID to that of mothers of non‐ID children; (2) assess the contribution of raising a child with ID to negative psychological outcomes for mothers; and (3) identify variables associated with negative psychological outcomes among mothers of children with ID.

Methods

The 1999 Office for National Statistics survey, Mental Health of Children and Adolescents in Great Britain, 1999, collected information on a multistage stratified random sample of 10 438 children between 5 and 15 years of age across 475 postal code sectors in England, Scotland and Wales. Secondary analysis was undertaken of the social and economic circumstances, and stress reported by 245 mothers of sampled children with ID and a comparison group of 9 481 mothers of sampled children who did not have ID.

Results The results indicate that:

(1) families supporting a child with ID were significantly economically disadvantaged when compared with families supporting a child who did not have ID; (2) when compared with mothers of sampled children who did not have ID, mothers of sampled children with ID reported that their child's difficulties resulted in greater social and psychological impact; (3) having a child with ID marginally reduced the odds of mothers screening positive for having mental health problems (once all other variables were taken into account); and (4) among mothers of children with ID, mental health problems were associated with the child's difficulties having a greater social impact, having a boy, the child experiencing more than one potentially stressful life event, poverty, receipt of means‐tested welfare benefits and ‘unhealthy’ family functioning.

Conclusions

These results highlight the importance of combating poverty among children with ID and their families, and the need to develop more complex models of understanding and intervention.
Following treatment of myogenous TMD patients with the temporomandibular opening index: an initial report
Authors: Miller V. J. , Karic V. V. , Myers S. L. , Bodner L.
Published: May 2003

Limitation of mandibular movement is one of the cardinal signs of temporomandibular disorders (TMD), usually assessed by measurement of maximum voluntary mouth opening. A new measure of assessing mandibular mobility, the temporomandibular opening index (TOI), is less dependent on variables such as age, gender and ramus length. It has also been found to be useful to categorize patients. This study examined changes in TOI as treatment progressed in a group of myogenous TMD patients. Seven patients with myogenous TMD were included in the study and the TOI determined at 0 and 2 weeks, 1 and 6 months after initiation of treatment. Treatment outcome was assessed on a 4 point scale, 0=none, 1=mild, 2=moderate, and 3=severe. Headache, neckache, pain (joints and muscles) and joint sounds were assessed. Nine patients with no signs or symptoms of TMD were included to obtain a normal TOI. The mean TOI of the patient group was 16·4% (s.d.=11·2%) initially and 3·95% (s.d.=1·0%) at 6 months, while mean treatment scores changed from 12·57 (s.d.=3·05) to 1·43 (s.d.=1·90). The mean TOI of the control group was 3·63 (s.d.=0·74). A paired t‐test showed that the TOI decreased significantly with time (P=0·02) while there was a concomitant decrease in treatment score (P=0·0003) over the same period. The TOI may be a useful method of following treatment of this group of myogenous TMD patients.
Effect of different filling materials in combination with intraradicular posts on the resistance to fracture of weakened roots
Authors: Marchi G. M. , Paulillo L. A. M. S. , Pimenta L. A. F. , De Lima F. A. P.
Published: May 2003

summary  The preservation and restoration of severely weakened pulpless teeth is a difficult and relatively unpredictable procedure. This study evaluated the resistance to fracture of experimentally weakened bovine roots internally reconstructed with different filling materials in combination with prefabricated post compared with restored roots that were relatively intact. The roots of 75 mandibular bovine incisors with similar bulks were selected. Of these, 60 were internally prepared to standardized dimensions, thereby simulating weakness. All roots were filled with different restorative materials. The specimens were submitted to the fracture resistance testing with the application of a tangential compressive loading at an angle of 135° in relation to the long axes of the roots. Results indicated statistically significant differences in relation to the root conditions. Weakened roots were less resistant to fracture than were controls. The roots restored with the resin cement demonstrated the lowest fracture resistance values, but statistically significant differences were observed only when compared with those restored by the resin‐modified glass–ionomer cement. Resin‐modified glass–ionomer cement, polyacid‐modified resin composite and resin composite behaved similarly without statistically significant differences among them. None of the materials evaluated were capable of achieving the fracture resistance recorded for unweakened controls.
An electromyographic evaluation of the bilateral symmetry and nature of masticatory muscle activity in jaw deformity patients during normal daily activities
Authors: Saifuddin M. , Miyamoto K. , Ueda H. M. , Shikata N. , Tanne K.
Published: May 2003

summary  This study was designed to investigate the nature of masticatory muscle activity and the balance in the bilateral symmetry of the masticatory muscle activity in jaw deformity patients. Fifteen patients (19·9 ± 5·3 years) with lateral shift of the mandible caused by transverse craniofacial deformity and 15 controls (28·6 ± 1·9 years) were used as the subjects in this study. Surface electromyographic (EMG) activities were recorded from the bilateral masseter and anterior temporal muscles during daytime (142 min, including mealtime) and sleep (142 min). The averaged rectified EMG values were normalized with reference to the EMG amplitude induced by a 98‐N bite force. Bilateral symmetry of masseter and anterior temporal muscle activities was examined using an asymmetry index (AI) for both the controls and the patients. The normalized activities of the masseter and anterior temporal muscles during normal daily activities were lower in patients than in the controls. Asymmetry indices in patients were significantly greater during usual daytime activities and sleep for the anterior temporal muscle and significantly smaller during sleep for the masseter muscle as compared with the controls. The results show that masticatory muscle activity is lower in these jaw deformity patients in association with more prominent asymmetry of anterior temporal muscle activity than in the controls. It is suggested that these findings are highly relevant to occlusal interference and instability because of malocclusion and lateral mandibular deviation.
A 3‐year clinical evaluation of a gallium restorative alloy
Authors: Kiremitci A. , Bolay S.
Published: May 2003

summary  Several alternative materials have been suggested to take the place of amalgam, because of the environmental toxic effects of its mercury component. One such material is gallium‐based alloy restoratives. The aim of this in vivo study was to compare the long‐term clinical performance of a commercial gallium alloy with an admixed high copper amalgam alloy. For this purpose, 32 gallium and 32 amalgam restorations were placed in molar teeth in 14 human subjects. All the selected patients had at least two molar teeth that required restoration. In this way both restoratives were used in the same oral cavity. The restorations were examined at baseline, 6 months, 1, 2 and 3 years. At baseline, six teeth restored with gallium alloy showed post‐operative sensitivity, whereas none of the amalgams were sensitive. At the end of 3 years, only a few amalgam restorations showed slight surface tarnish and marginal integrity loss. None of them needed replacement. Of the 32 gallium restorations placed, five had to be removed because of sensitivity, corrosion and tooth fracture. Also dramatic surface roughness and corrosion were noticed in 12 gallium restoration. According to the results of this clinical study, gallium‐based restoratives should not be used before their physical properties are improved.
Finite element analysis of strength characteristics of various resin based restorative materials in Class V cavities
Authors: Yaman S. D. , şahin M. , Aydin C.
Published: May 2003

summary  This study investigated the strength characteristics of various composites (Tetric Ceram, Tetric Flow, Prisma AP.H, Synergy Duo Shade, Synergy Compact, and Z 100) and compomers (Compoglass, Compoglass F, Dyract AP, F 2000) that were applied in a Class V cavity of a maxillary central incisor. The study was conducted by using a 3‐dimensional finite element approach and in the study ansys package program was used. The tooth model had 294 elements and 420 nodes. The teeth considered were assumed to be subjected to an incisal load of 200 N acting at an angle of 26° with the longitudinal axis of the tooth but the effects of different loading angles and different loads were also analysed. Hence, the loads of 100 and 400 N and the loading angles of 0° representing bruxism and 90° representing a traumatic load were also taken into consideration. The effects of the cavity preparation size were also studied. It was determined that any increase in the loading angle and/or the amount of the load resulted in a proportional increase in the stresses developed in the tooth. Furthermore it was also verified that, as a cavity weakens the tooth structure by creating a discontinuity in an intact tooth, the larger sized cavity preparations inevitably cause larger stresses to be developed in the tooth. Strictly from the mechanical point of view, the stresses developed in the restored teeth were determined to be inversely proportional with the modulus of elasticity of the restorative materials. Therefore within the scope of the study Z 100 was found to be superior to the other materials concerned.
Effect of preparation mode on Class II resin composite repair
Authors: Frankenberger R. , Roth S. , Krämer N. , Pelka M. , Petschelt A.
Published: May 2003

summary  Complete removal of failed posterior resin composite fillings is time‐expensive and involves the risk of removing sound tooth substance. In any case of failure within the composite material, intra‐oral repair would be favourable. This in vitro study was conducted to examine the effect of different preparation and bonding modes on integrity of repaired restorations. Forty‐eight direct Class II resin composite restorations (Syntac Classic®/Tetric Ceram®) were placed in extracted human third molars. The specimens were stored for 365 days and then replaced partially by removing the central part of the proximal box with all margins located in composite. The partial repairs were placed with the same materials after pre‐treatment with a silicon carbide bur and Syntac Classic (n = 8). Preparation modes have been (i) box‐only parallel, (ii) box‐only with undercuts, (iii) box with undercuts and additional occlusal retention. The repairs were performed either with (i) Tetric Ceram® or with (ii) Tetric Flow® as thin lining covered with Tetric Ceram®. Before and after thermomechanical loading (100 000 cycles of 50 N and 2500 cycles between +5 and +55 °C in an artificial mouth), marginal quality between aged and freshly applied composite was evaluated by SEM at ×200 magnification and microleakage was observed by light microscopy at ×50 magnification. Box‐only preparations exhibited a better fatigue resistance than preparations with additional occlusal retention. This observation was independent from the presence of undercuts (P < 0·05). An intermediary layer of flowable resin composite tended to result in better marginal quality, however, not being statistically significant.
Changes in properties of polyacid‐modified composite resins (compomers) following storage in acidic solutions
Authors: Nicholson J. W. , Gjorgievska E. , Bajraktarova B. , Mckenzie M. A.
Published: May 2003

summary  The interaction of three polyacid‐modified composite resins (compomers) with various acidic storage solutions, and also water, over periods of time up to 6 months has been studied and compared with those of a glass–ionomer and a composite resin. This interaction has been shown to vary in a complex way with length of storage and nature of the acid, and citric acid was found to be the most aggressive storage medium for glass–ionomer cement, and also for the compomers. The pure composite resin, by contrast, was relatively unaffected by all of the acid solutions examined. In all acids, the compomers showed a distinct buffering effect, i.e. they increased the pH towards neutral, as did the glass–ionomer. The extent of this also varied with duration of storage and nature of the acid. The biaxial flexure strength was determined and found to be essentially unaffected by the complex chemical interactions with acidic storage solutions. Values obtained for the compomers were lower than those of the composite resin, but above those of the glass–ionomer. Fourier‐transform infrared (FT‐IR) spectroscopy was employed to study the changes in the compomers following storage in the aqueous media, but bands were broad and no detailed assignments could be made. There were changes in the region of the spectra associated with metal carboxylates however, and this indicates that the secondary acid–base reaction had occurred following water uptake.
Mandibular condyle movement during mastication of foods
Authors: Komiyama O. , Asano T. , Suzuki H. , Kawara M. , Wada M. , Kobayashi K. , Ohtake S.
Published: May 2003

summary  This study evaluated the mandibular condyle displacement on the working side while masticating certain foods with different textures. For referencing the mandibular condyle movement, the range of voluntary border movement of the mandibular condyle was determined based on the analysis of the sagittal, left lateral and right lateral border motion using Posselt's figure. The test foods consisted of cheese, peanuts, and beef jerky. During mastication of cheese and peanuts, the amount of displacement of the mandibular condyle in all directions was within the range of border movement. Significant posterior and superior shifts of the mandibular condyle were observed during mastication of beef jerky, compared with the findings obtained during border movement. Accordingly, it is suggested that prolonged mastication of hard fibrous foods, may stimulate the temporomandibular joint structure and mandibular dysfunction patients should limit their intake of such foods.