bluuebunny/crossref_metadata_2025_split huggingface dataset:
Functional ecology of shrub seedlings after a natural recruitment event at the Nevada Desert FACE Facility
Authors: HOUSMAN DAVID C. , ZITZER STEPHEN F. , HUXMAN TRAVIS E. , SMITH STANLEY D. 
Published: May 2003

AbstractSeedling recruitment is an important determinant of community structure in desert ecosystems. Positive photosynthetic growth and water balance responses to increasing atmospheric carbon dioxide (CO2) concentrations ([CO2]) are predicted to be substantial in desert plants, suggesting that recruitment could be stimulated. However, to date no studies have addressed the response of perennial plant recruitment in natural populations of desert shrubs exposed to elevated [CO2]. In April 1997, we employed Free‐Air Carbon Dioxide Enrichment (FACE) in order to increase atmospheric [CO2] in an undisturbed Mojave Desert ecosystem from ambient (∼∼ 370 µmol mol−1) to elevated CO2 (∼∼ 550 µmol mol−1). From 1997 to 2001 we seasonally examined survival, growth, gas exchange and water potential responses of Larrea tridentata and Ambrosia dumosa seedlings that germinated in Fall, 1997. Recruitment densities were not influenced by [CO2] in either species, although a two‐fold higher adult Ambrosia density under elevated [CO2] resulted in two‐fold higher seedling density (0.87 vs 0.40 seedlings m−2). Mortality was greatest for both species during the first summer (1998), despite above‐average rainfall during the previous Winter–Spring. A significant [CO2] × time interaction revealed that early survival was greater under elevated CO2, whereas a significant species time interaction revealed that overall survival was greater for Ambrosia (28%) than for Larrea (15%), regardless of [CO2]. Microsite (understorey or interspace) alone had no significant influence on survival. Significant species, microsite and species × microsite effects on growth (seedling height, stem diameter and canopy size) were found, but elevated CO2 had minimal impact on these parameters. Photosynthetic rates (Asat) for both species were higher at elevated [CO2] during certain seasons, but not consistently so. These results suggest that increased atmospheric [CO2] may enhance carbon (C) assimilation and survival of aridland perennial shrubs during favourable growing conditions, but that it may not counteract the effects of prolonged drought on mortality.
Fluctuations of Vanessa cardui butterfly abundance with El Niño and Pacific Decadal Oscillation climatic variables
Authors: VANDENBOSCH ROBERT 
Published: May 2003

AbstractAnnual 4th of July Butterfly Count data spanning more than 20 years are examined to explore Vanessa cardui (Painted Lady) population fluctuations with ENSO (El Niño) and Pacific Decadal Oscillation (PDO) indices. California, Colorado and Nebraska censuses exhibit a strong positive correlation with the strong El Niño events of 1982–1983 and 1997–1998 and the weaker event of 1991–1992. Regression analysis shows the population fluctuations are strongly coupled to climate variations on both short (El Niño) and longer (Pacific Decadal Oscillation) time scales. Recognizing the sensitivity to these time scales is important for predicting longer‐term global climate change effects.
Environmental control of fine root dynamics in a northern hardwood forest
Authors: TIERNEY GERALDINE L. , FAHEY TIMOTHY J. , GROFFMAN PETER M. , HARDY JANET P. , FITZHUGH ROSS D. , DRISCOLL CHARLES T. , YAVITT JOSEPH B. 
Published: May 2003

AbstractUnderstanding how exogenous and endogenous factors control the distribution, production and mortality of fine roots is fundamental to assessing the implications of global change, yet our knowledge of control over fine root dynamics remains rudimentary. To improve understanding of these processes, the present study developed regression relationships between environmental variables and fine root dynamics within a northern hardwood forest in New Hampshire, USA, which was experimentally manipulated with a snow removal treatment. Fine roots (< 1 mm diameter) were observed using minirhizotrons for 2 years in sugar maple and yellow birch stands and analyzed in relation to temperature, water and nutrient availability. Fine root dynamics at this site fluctuated seasonally, with growth and mortality peaking during warmer months. Monthly fine root production was strongly associated with mean monthly air temperature and neither soil moisture nor nutrient availability added additional predictive power to this relationship. This relationship exhibited a seasonal temperature hysteresis, which was altered by snow removal treatment. These results suggest that both exogenous and endogenous cues may be important in controlling fine root growth in this system. Proportional fine root mortality was directly associated with mean monthly soil temperature, and proportional fine root mortality during the over‐winter interval was strongly related to whether the soil froze. The strong relationship between fine root production and air temperature reported herein contrasts with findings from some hardwood forest sites and indicates that controls on fine root dynamics vary geographically. Future research must more clearly distinguish between endogenous and exogenous control over fine root dynamics in various ecosystems.
Interannual variability of plant phenology in tussock tundra: modelling interactions of plant productivity, plant phenology, snowmelt and soil thaw
Authors: Van Wijk M. T. , Williams M. , J. A.  , G. R.  
Published: May 2003

AbstractWe present a linked model of plant productivity, plant phenology, snowmelt and soil thaw in order to estimate interannual variability of arctic plant phenology and its effects on plant productivity. The model is tested using 8 years of soil temperature data, and three years of bud break data of Betula nana. Because the factors that trigger the end of the growing season of arctic vegetation are less well known than those of the start of the growing season, three hypotheses were formulated and tested for their effects on productivity and its sensitivity to climate change; the hypothesised factors determining the end of the growing season were frost, photoperiod and periodic constraints.The performance of the soil thermal model was good; both the onset of soil thaw in spring and the initiation of freezing in autumn were predicted correctly in most cases. The phenology model predicted the bud break date of Betula nana closely for the three different years. The soil thaw model predicted similar growing season start dates under current climate as the models based on sum of temperatures, but it made significantly different predictions under climate change scenarios, probably because of the non‐linear interactions between snowmelt and soil thaw. The uncertainty about the driving factors for the end of the growing season, in turn, resulted in uncertainty in the interannual variability of the simulated annual gross primary productivity (GPP). The interannual variability ranged from − 25 to + 26% of the mean annual GPP for the frost hypothesis, from − 20 to + 20% for the photoperiod hypothesis and only from − 7 to + 7% for the periodic hypothesis. The different hypotheses also resulted in different sensitivity to climate change, with the frost hypothesis resulting in 30% higher annual GPP values than the periodic hypothesis when air temperatures were increased by 3 °C.
Soil‐surface carbon dioxide efflux and microbial biomass in relation to tree density 13 years after a stand replacing fire in a lodgepole pine ecosystem
Authors: LITTON CREIGHTON M. , RYAN MICHAEL G. , KNIGHT DENNIS H. , STAHL PETER D. 
Published: May 2003

AbstractThe effects of fire on soil‐surface carbon dioxide (CO2) efflux,FS, and microbial biomass carbon,Cmic, were studied in a wildland setting by examining 13‐year‐old postfire stands of lodgepole pine differing in tree density (< 500 to > 500 000 trees ha−1) in Yellowstone National Park (YNP). In addition, young stands were compared to mature lodgepole pine stands (∼110‐year‐old) in order to estimate ecosystem recovery 13 years after a stand replacing fire. Growing seasonFSincreased with tree density in young stands (1.0 µmol CO2 m−2 s−1in low‐density stands, 1.8 µmol CO2 m−2 s−1in moderate‐density stands and 2.1 µmol CO2 m−2 s−1in high‐density stands) and with stand age (2.7 µmol CO2 m−2 s−1in mature stands). Microbial biomass carbon in young stands did not differ with tree density and ranged from 0.2 to 0.5 mg C g−1dry soil over the growing season;Cmicwas significantly greater in mature stands (0.5–0.8 mg C g−1dry soil). Soil‐surface CO2efflux in young stands was correlated with biotic variables (above‐ground, below‐ground and microbial biomass), but not with abiotic variables (litter and mineral soil C and N content, bulk density and soil texture). Microbial biomass carbon was correlated with below‐ground plant biomass and not with soil carbon and nitrogen, indicating that plant activity controls not only root respiration, butCmicpools and overallFSrates as well. These findings support recent studies that have demonstrated the prevailing importance of plants in controlling rates ofFSand suggest that decomposition of older, recalcitrant soil C pools in this ecosystem is relatively unimportant 13 years after a stand replacing fire. Our results also indicate that realistic predictions and modeling of terrestrial C cycling must account for the variability in tree density and stand age that exists across the landscape as a result of natural disturbances.
MuSICA, a CO2, water and energy multilayer, multileaf pine forest model: evaluation from hourly to yearly time scales and sensitivity analysis
Authors: OGÉE J. , BRUNET Y. , LOUSTAU D. , BERBIGIER P. , DELZON S. 
Published: May 2003

AbstractThe current emphasis on global climate studies has led the scientific community to set up a number of sites for measuring long‐term biospheric fluxes, and to develop a wide range of biosphere–atmosphere exchange models. This paper presents a new model of this type, which has been developed for a pine forest canopy. In most coniferous species the canopy layer is well separated from the understorey and several cohorts of needles coexist. It was therefore found necessary to distinguish several vegetation layers and, in each layer, several leaf classes defined not only by their light regime and wetness status but also by their age. This model, named MuSICA, is a multilayer, multileaf process‐based model. Each submodel is first independently parameterized using data collected at a EUROFLUX site near Bordeaux (Southwestern France). Particular care is brought to identify the seasonal variations in the various physiological parameters. The full model is then evaluated using a two‐year long data set, split up into 12 day‐type classes defined by the season, the weather type and the soil water status. Beyond the good overall agreement obtained between measured and modelled values at various time scales, several points of further improvement are identified. They concern the seasonal variations in the stomatal response of needles and the soil/litter respiration, as well as their interaction with soil or litter moisture. A sensitivity analysis to some of the model features (in‐canopy turbulent transfer scheme, leaf age classes, water retention, distinction between shaded and sunlit leaves, number of layers) is finally performed in order to evaluate whether significant simplifications can be brought to such a model with little loss in its predictive quality. The distinction between several leaf classes is crucial if one is to compute biospheric fluxes accurately. It is also evidenced that accounting for in‐canopy turbulent transfer leads to better estimates of the sensible heat flux.
Using satisfaction to measure the quality of palliative care: a review of the literature
Authors: Aspinal Fiona , Addington‐Hall Julia , Hughes Rhidian , Higginson Irene J. 
Published: May 2003

Background. The advent of clinical governance in British health policy has placed increased demands on health care providers and practitioners to ascertain the quality of their services. Traditional indicators of quality of health care, such as death or recovery rates, are not appropriate in palliative care. Thus, it is important to establish alternative approaches to measuring the quality of palliative care services and interventions. Aims. Satisfaction levels have been used widely in palliative care to assess quality. A literature review was conducted which aimed to explore the strengths and weaknesses of using satisfaction as an indicator of the quality of palliative care services. It also aimed to provide a solid basis upon which further work could be built. Methods. Five electronic databases were searched using key words and phrases and key authors. Hand searches were conducted of four journals that contributed significantly to the concept of satisfaction, and reference lists of reviewed papers were scrutinized. Relevant papers were reviewed, data were extracted and these data were thematically analysed. Findings. There are a number of important unresolved issues in the literature with regard to using satisfaction as an indicator of the quality of palliative care services. First, few alternatives to satisfaction are available. Secondly, satisfaction is under‐theorized and no widely accepted definition exists. Thirdly, there are methodological inconsistencies across studies. It is important to take into account these findings when planning and implementing change following service evaluation using satisfaction as a measure. Conclusions. Relying on findings of satisfaction surveys to determine clinical and policy amendments in palliative care may not result in improvements in overall quality of care. Using satisfaction as a method of assessing the quality of health care services is particularly problematic and requires further investigation in both practical and conceptual terms.
Clinical practice in a computer world: considering the issues
Authors: Hughes Rhidian A 
Published: May 2003

Background. In an era when information technology developments are being harnessed by governments to improve patient care, it is important to consider the issues raised by the use of computers in health care practice and policy. Aim. The aim of this paper is to provide an appraisal of considerations raised by the use of computers in health care. Review focus. Drawing on a range of studies in the social and medical sciences, the paper reviews the considerations. The introduction to the paper maps out the policy context, which is followed by three substantive sections: first, computer hardware and software considerations; second, issues around confidentiality; and third, personal, social and cultural considerations. Conclusion. This paper demonstrates that information technology developments must be allied with government or state direction and should be informed by evidence. Whilst the issues discussed are of primary relevance to the United Kingdom National Health Service, they have wider relevance to health care systems internationally.
Functional status in older women following hip fracture
Authors: Curry Linda Cox , Hogstel Mildred O. , Davis Gail C. 
Published: May 2003

Background. Women aged 65 years and over are at high risk for a fractured hip because of osteoporosis. One of the devastating effects of a fracture is the loss of ability to live independently. Aim. The major aim of this study was to describe the functional status, or ability to perform activities of daily living, of women aged 65 years and older who had experienced a fractured hip in the recent past and to explore possible differences in selected variables (e.g. age and length of rehabilitation) for those who were fully performing activities of daily living at least 6 months after fracture and those who were not. Design. Following Institutional Review Board approval, data were collected from 23 Caucasian women ranging from 65 to 95 years of age (M = 82, sd = 6·83) who had experienced fractured hips related to a fall in the recent past (6 months to 4 years). All were living independently prior to their fractures. Three Registered Nurses, in a structured interview, collected the data using a Demographic Data Form, an Osteoporosis Risk Factor Checklist, the Katz Index of Independence in Activities of Daily Living, and the Lawton Instrumental Activities of Daily Living Scales. Results. Nine of the participants reported prior fractures, suggesting that this could have been a risk factor for this group. Eighteen achieved the maximum independence score of six on the Katz Index of Independence in Activities of Daily Living; help with bathing was required by the other five. Of the Instrumental Activities of Daily Living, those requiring physical activity for home maintenance were the most problematic. Ability to perform Instrumental Activities of Daily Living was significantly related to ability to perform the activities required to live independently. Conclusions. Results suggest that achieving a functional level that will support independence is possible for older women who were residing independently prior to a hip fracture.
Negotiated care: a model for nursing work in the renal setting
Authors: Polaschek Nick 
Published: May 2003

Aim. This article outlines a model for the nursing role in the chronic health care context of renal replacement therapy. Methods. Materials from several streams of literature are used to conceptualize the potential for nursing work in the renal setting as negotiated care. In order to present the role of the renal nurse in this way it is contextualized by viewing the renal setting as a specialized social context constituted by a dominant professional discourse and a contrasting client discourse. Discussion. While performing specific therapeutic activities in accord with the dominant discourse, renal nurses can develop a relationship with the person living on dialysis, based on responsiveness to their subjective experience reflecting the renal client discourse. In contrast to the language of noncompliance prevalent in the renal setting, nurses can, through their relationship with renal clients, facilitate their attempts to negotiate the requirements of the therapeutic regime into their own personal life situation. Nurses can mediate between the dominant and client discourses for the person living on dialysis. Care describes the quality that nurses actively seek to create in their relationships with clients, through negotiation, in order to support them to live as fully as possible while using renal replacement therapy. Conclusion. Within chronic health care contexts, shaped by the acute curative paradigm of biomedicine, the model of nursing work as negotiated care has the potential to humanize contemporary medical technologies by responding to clients' experiences of illness and therapy.
Barriers to paediatric nurses' research utilization
Authors: McCleary Lynn , Brown G. Ted 
Published: May 2003

Background. A number of studies have investigated barriers to research utilization among nurses in various countries, and standardized scales have been validated to study this. Reported barriers have been categorized as individual, organizational and environmental, with organizational characteristics generally accounting for more variance. However, information about research utilization among paediatric nurses is lacking. Aim. The objective of the research reported here was to investigate barriers to research utilization and relationships between those barriers and participation in research, self‐reported research utilization and education among paediatric nurses. Design. A survey of all nurses in a paediatric teaching hospital; 176 nurses (33·3%) responded. Two standardized measures were used, the Barriers Scale and the Edmonton Research Orientation Scale. Results. Lack of time to read research was the most frequently cited barrier to using research and administrators not allowing implementation was the least frequently cited. Characteristics of the communication and of the setting were more likely to be cited as barriers to research use than were characteristics of the nurse. Nurses who reported higher levels of actual research use were slightly less likely to see characteristics within themselves as barriers. Those who had taken a course about reading or using research were more likely to see the organization as a barrier. Barriers to research use were not associated with self‐reported understanding of research. Conclusions. These results are congruent with previous findings that implementing research in practice is a complex process. They indicate that individual nurses' knowledge about research may not be as important as the process by which organizations implement research. However, the Barriers Scale measures general perceptions about barriers to research utilization and not nurses' specific experiences with barriers to implementing particular research.
The association between knee temperature and pain in elders with osteoarthritis of the knee: a pilot study
Authors: Tsai Pao‐Feng , Richards Kathy , Tatom Iris 
Published: May 2003

Background. Osteoarthritis is a highly prevalent, disabling condition that causes significant pain and suffering among older adults. Cognitively impaired elders are as susceptible to osteoarthritis as their peers. However, since they have diminished ability to communicate their pain, an alternative method to detect osteoarthritis pain in cognitively impaired elders is urgently needed. Because the late stages of osteoarthritis involve joint inflammation with a mild increase in local temperature, skin surface temperature might reasonably be expected to serve as a proxy measure of osteoarthritis pain. If knee surface temperature could be shown to predict pain in cognitively intact elders, it could be used as a proxy measure of pain for cognitively impaired elders.Aim. To test this, the study reported here assessed the relationship between knee surface temperature and pain in cognitively intact elders with osteoarthritis of the knee.Methods. We recruited 12 cognitively intact elders with documented osteoarthritis of the knee who lived in retirement apartments. Elders' pain and knee temperature were measured three times on three separate occasions. Osteoarthritis pain of the knee was measured using the Knee Pain Scale and the Western Ontario and McMaster Osteoarthritis Index pain subscale. A YSI Model 4000 Dual Channel Display Telethermometer was used to measure knee temperature.Results. We found no significant associations between knee temperature and any of the pain measures used, with one exception. However, body mass index, amount of pain medication used and activity level observed during the interview were significantly related to elders' pain.Conclusion. Knee temperature does not appear to predict knee pain in elders with osteoarthritis of the knee. Body mass index, use of pain medication and activity level are better predictors of this.