bluuebunny/crossref_metadata_2025_split huggingface dataset:
The influence of fire on the demography of a dominant grass species of West African savannas, Hyparrhenia diplandra
Authors: Garnier Lisa K. M. , Dajoz Isabelle 
Published: March 2003

Summary

Effects of fire on the demography of a population of a long‐lived perennial tussock grass, Hyparrhenia diplandra, were investigated in a West African savanna that normally burns annually. Seedling growth, survival and fecundity were recorded in burned and unburned plots during 3 years for a first cohort and during 1 year for a second cohort initiated 1 year later.
Seedling growth and survival rates were significantly higher in unburned plots, with larger seedlings surviving burning better. Regardless of treatment/fire regime, seedlings grew faster when located further from the nearest tuft, but differences between clones showed that growth rate also had a genetic basis in this apomictic species. Adult survival was always high, but exclusion of fire increased size, and therefore age, at maturity. Fire therefore affects life‐history traits in this grass species of fire‐prone environments.
Size‐structured matrix models were constructed separately for each fire treatment, incorporating demographic and fire parameters estimated from field data.
The asymptotic population growth rate was higher in the unburned model (λ = 1.23) than in the burned one (λ = 1.07), indicating that the population of H. diplandra expanded quickly in the absence of fire.
Overall, results indicate that annual burning limits population growth rate. Less frequent, but still regular fires may allow establishment while preventing the accumulation of litter and accelerating nutrient recycling; thus lead to more stable populations than in the total absence of fire.
Storage and the delayed costs of reproduction in the understorey perennial Lathyrus vernus
Authors: Ehrlén Johan , Van Groenendael Jan 
Published: March 2003

Summary

A trade‐off between current and future reproduction, often referred to as the cost of reproduction, is a fundamental assumption in life history theory. In long‐lived plants, large absolute differences in size between individuals, storage of resources between reproductive events and organ preformation may make such costs difficult to demonstrate, especially when only natural variation is considered.
The long‐lived legume Lathyrus vernus shows large size differences compared with variation in carbon resource allocation, and is known to store resources in below‐ground rhizomes. We therefore followed individual plants over a period of 4 consecutive years. We examined the cost of reproductive investment by comparing the performance of untreated plants that differed in size and herbivore damage. We also compared controls with plants where we experimentally reduced flowering in terms of fitness measured as: survival, growth, flower number, fruit:flower ratio and storage.
Natural patterns of flowering and fruiting provided no evidence of a negative relationship between current and future reproduction. Individuals that produced fruits did not experience a lower probability of surviving and producing fruits the following season compared with flowering individuals that failed to produce any fruits, even when differences in above‐ground size and herbivore damage were taken into account.
Flower removal in a single season increased the allocation to the rhizome but the size of shoot buds for the next season was not increased. Experimental manipulation of reproductive effort by repeated removal of flowers during 3 consecutive years, however, resulted in a significant increase in vegetative size and the probability of flowering and setting fruit compared with control plants.
While long‐term data on natural variation in fruit production and short‐term experimental data provided no evidence of a cost of reproduction, such a cost is still present, although detectable only after repeated flower removal.
Development of a negative plant–soil feedback in the expansion zone of the clonal grass Ammophila arenaria following root formation and nematode colonization
Authors: Van Der Stoel C. D. , Van Der Putten W. H. , Duyts H. 
Published: March 2003

Summary

The feedback between individual plants and their soil communities is a major driver of plant community processes. We analyse the rate at which plant–soil feedback develops in the root zone of the clonal dune grass Ammophila arenaria.
Ammophila arenaria grows vigorously when it can form new roots in newly deposited windblown beach sand. The colonization zone is hypothesized to provide an enemy‐free space, with root pathogens and parasites possibly contributing to degeneration of A. arenaria when deposition stops.
We quantified root biomass and plant parasitic nematode densities in new and 1‐year‐old root zones, as well as in degenerate stands, in the field at monthly intervals. Each month, we studied the biomass production of Ammophila seedlings in controlled conditions in sterilized and non‐sterilized soil from the different sampling sites, with and without nematicides.
Colonization of newly deposited sand by the endoparasitic nematodes Heterodera arenaria and Pratylenchus spp. within 1 month of root formation coincided with a negative feedback in the bioassays. Nematicides counteracted growth reduction significantly, but their effectiveness decreased in soil samples collected later in the growing season.
In older layers, roots and nematodes were already present before the sampling started. Growth reduction in unsterilized sand was observed at all sampling events, but was not counteracted by nematicides.
In the field, root biomass of A. arenaria in the newly colonized sand increased throughout the growing season, despite the development of a negative plant‐soil feedback.
We conclude that the development of negative plant–soil feedback in the root zone of A. arenaria closely follows the colonization of newly deposited sand by roots and then by the endoparasitic nematode species Heterodera arenaria. There seems to be a shift in organisms causing this feedback during the first growing season, but root biomass nevertheless increases. However, in older root layers and in the degenerate stand, ongoing negative plant–soil feedback may contribute to a gradual decrease in root biomass.
Stand dynamics over 18 years in a southern mixed hardwood forest, Texas, USA
Authors: Harcombe P. A. , Bill C. J. , Fulton M. , Glitzenstein J. S. , Marks P. L. , Elsik I. S. 
Published: March 2003

Summary 1 Using 18 years of permanent‐plot data from a 4‐ha stand, we investigated whether stand dynamics is predictable, i.e. driven by competition (inferred from species shade tolerances), or unpredictable (driven by frequent exogenous disturbance or other factors). We also considered whether small disturbance might accelerate or retard succession. The study involved dynamics of stems ≥ 4.5 cm diameter at breast height (d.b.h.) for 10 important species in a southern mixed hardwood forest 80 years after selective removal of Pinus taeda. 2 Shade‐tolerant species (Ilex opaca, Fagus grandifolia, Magnolia grandiflora, Acer rubrum, Nyssa sylvatica) increased in small d.b.h. classes, whereas intermediate (Quercus alba) and shade‐intolerant species (Q. nigra, Q. hemisphaerica, Liquidambar styraciflua, Pinus taeda) did not. 3 Per‐capita ingrowth was higher for shade‐tolerant species (0.016–0.024) than for intermediate and shade‐intolerant species (0–0.006), whereas mortality was lower ((0.006–0.015 vs. 0.019–0.035). 4 Over 18 years, ingrowth exceeded mortality loss slightly, resulting in an increase in number of stems of about 1%, from 995 to 1029 stems ha−1; average live basal area (BA; 35.9 m2 ha−1) varied by less than 2% over eight surveys spanning 18 years. Basal area increased substantially for three species (Ilex opaca, Pinus taeda, Acer rubrum), and declined strongly for three others (Quercus nigra, Q. hemisphaerica and Fagus grandifolia). 5 The stand d.b.h. distribution had a rotated sigmoid form which became flatter over time. Species d.b.h. distributions were mostly bell‐shaped for intolerant species, and irregular‐to‐monotonic declining for shade‐tolerant species. Over time, bell‐shaped distributions moved to the right and irregular distributions remained irregular. 6 A hurricane in 1986 caused loss of 4.5% of standing BA. Compositional change was most rapid during the hurricane interval and ingrowth was highest in the two intervals following the hurricane. Effects on species trends in density, basal area, mortality or recruitment were minor. 7 Temporal trends in species abundances mostly supported the hypothesis of predictable successional change related to competition for light. However, d.b.h. distributions of shade‐tolerant species and rapid declines in BA of Quercus nigra and Fagus indicated that other processes are also important and will limit predictability of change.
Spatial and temporal variations in mortality of the biennial plant, Lysimachia rubida: effects of intraspecific competition and environmental heterogeneity
Authors: Suzuki Ryo O. , Kudoh Hiroshi , Kachi Naoki 
Published: March 2003

Summary

We studied mortality, growth and spatial distribution of individuals of Lysimachia rubida to elucidate causes and consequences of temporal and spatial variations in mortality. This short‐lived monocarpic biennial grows in open dry habitats on rocky coastal cliffs of the subtropical Bonin (Ogasawara) Islands, Japan.
All individuals of two successive cohorts that appeared in a 8 × 8‐m quadrat were mapped, and their fate and size were recorded at 2–3 month intervals from March 1998 to July 2000. We analysed spatial and temporal changes in the relative importance of plant size, local densities of neighbouring plants and ground surface conditions to determine plant mortality. We also examined spatially non‐random mortality and its spatial scales.
Patchy seed dispersal from scattered mother plants resulted in a clumped distribution of seedlings. During the growth cycle of L. rubida, we recognized two growth stages that differed in the relative importance of the factors affecting plant mortality.
At the earlier growth stage, after germination in March until July, mortality was caused mainly by local density. Smaller plants within areas of high local densities were more likely to die. The spatial patterns of surviving and dead plants tended to be regular and aggregated, respectively, in comparison with those expected from random mortality. The spatial scale of aggregation of the dead plants was 5–25 cm, corresponding to the distance of direct interactions between neighbours.
At the later growth stages, in October until May of the following year, mortality was affected mainly by ground surface conditions. Both surviving and dead plants were spatially aggregated at spatial scales of 20–100 cm. Plants tended to survive in microhabitats of smaller gravel, which had a greater water‐holding capacity.
This study also showed the consequence of spatial variations in mortality on population structures of L. rubida. Patchy seed dispersal and subsequent temporal and spatial variations in mortality are likely to contribute to the scattered distribution of L. rubida individuals observed at the study site.
Hydrological studies on blanket peat: the significance of the acrotelm‐catotelm model
Authors: Holden J. , Burt T. P. 
Published: March 2003

Summary

Runoff production in blanket peat catchments of the northern Pennine hills, UK was measured through monitoring and experimentation at the plot, hillslope and catchment scale. Water flow from soil pipes was measured in one of the study catchments and overland flow, throughflow and water table were measured in runoff plots; rainfall simulation and tension‐infiltrometry provided information on infiltration characteristics of the peat.
Saturation‐excess overland flow was found to dominate the flashy flow regime; acrotelm stormflow, subsurface pipeflow and macropore flow were also found to be important components of the ecohydrological system.
Surface cover, topography and preferential flowpaths were found to be important factors in controlling infiltration and runoff production.
Streamflow generation processes that are consistent with the acrotelm‐catotelm model are shown to occur in blanket peat with and without Sphagnum cover, but in one of the catchments studied an estimated 10% of the discharge bypassed this route and discharged via pipes.
The spatial and temporal variation in hillslope‐scale runoff production was demonstrated in the study catchments. This variability in runoff production will be important for hydroecological understanding in peatlands but is often neglected because of over‐simplification of processes provided by the traditional two‐dimensional acrotelm‐catotelm model.
Evidentiary challenges to evidence‐based medicine
Authors: Djulbegovic Benjamin , Morris Lou , Lyman Gary H. 
Published: March 2003

AbstractThe evidence‐based medicine (EBM) movement has exerted a strong influence on contemporary medicine. It has been used to define the hierarchy of knowledge in clinical medicine by classifying clinical findings according to the perceived relevance and validity of the respective methodologies of studies from which evidence was collected. In the spectrum of theories of knowledge, EBM predominantly relies on findings obtained from population‐derived clinical research. This reliance on knowledge obtained from population studies sharply contrasts with a physiologic model of clinical knowledge advocated by basic science researchers and many clinicians. An apparent schism between proponents of physiologic and population models in the approach to the practice of medicine has been created. This dichotomy between practising physicians and EBM physicians in the approach to clinical knowledge should not be irreconcilable. We advocate a consilient approach to the interpretation of evidence and the integration of medical knowledge. This approach relies on ‘linking of facts and fact‐based theory across various disciplines to create a common groundwork of explanation’.
Including qualitative research in systematic reviews: opportunities and problems
Authors: Dixon‐Woods Mary , Fitzpatrick Ray , Roberts Karen 
Published: March 2003

AbstractQualitative research has been increasingly recognized in recent years as having a distinctive and important contribution to make to health care research. It is capable of being used as a methodologically sufficient approach in its own right, as a precursor to quantitative studies, during or after trials to explain processes and outcomes, and as a means of enhancing the link between evidence and practice. However, qualitative research has been little used as an evidence resource for systematic reviews. We argue that formal synthesis of both qualitative and quantitative forms of research is essential, and we discuss some of the problems that need to be overcome in carrying out such syntheses. These include methodological prejudice, problems in searching for qualitative evidence, and issues in synthesizing qualitative data. We call for progress to be made on the science and methods of including qualitative research in the evidence base of medicine.
Outcomes‐based trial of an inpatient nurse practitioner service for general medical patients
Authors: Pioro Mathilde H. , Landefeld C. Seth , Brennan Patricia F. , Daly Barbara , Fortinsky Richard H. , Kim Unhee , Rosenthal Gary E. 
Published: March 2003

AbstractAlthough teaching hospitals are increasingly using nurse practitioners (NPs) to provide inpatient care, few studies have compared care delivered by NPs and housestaff or the ability of NPs to admit and manage unselected general medical patients. In a Midwest academic teaching hospital 381 patients were randomized to general medical wards staffed either by NPs and a medical director or medical housestaff. Data were obtained from medical records, interviews and hospital databases. Outcomes were compared on both an intention to treat (i.e. wards to which patients were randomized) and actual treatment (i.e. wards to which patients were admitted) basis. At admission, patients assigned randomly to NP‐based care (n = 193) and housestaff care (n = 188) were similar with respect to demographics, comorbidity, severity of illness and functional parameters. Outcomes at discharge and at 6 weeks after discharge were similar (P > 0.10) in the two groups, including: length of stay; charges; costs; consultations; complications; transfers to intensive care; 30‐day mortality; patient assessments of care; and changes in activities of daily living, SF‐36 scores and symptom severity. However, after randomization, 90 of 193 patients (47%) assigned to the NP ward were actually admitted to housestaff wards, largely because of attending physicians and NP requests. None the less, outcomes of patients admitted to NP and housestaff wards were similar (P > 0.1). NP‐based care can be implemented successfully in teaching hospitals and, compared to housestaff care, may be associated with similar costs and clinical and functional outcomes. However, there may be important obstacles to increasing the number of patients cared for by NPs, including physician concerns about NPs' capabilities and NPs' limited flexibility in managing varying numbers of patients and accepting off‐hours admissions.
Hawthorne effects and research into professional practice
Authors: Holden John D. 
Published: March 2003

AbstractThe Hawthorne studies in the 1930s demonstrated how difficult it is to understand workplace behaviour, and this includes professional performance. Studies of interventions to improve professional performance, such as audit, can provide useful information for those considering using such methods, but cannot replace judgement. In particular, there is no single phenomenon that can be labelled ‘the Hawthorne effect’. The process of triangulation, considering a subject from different perspectives, might overcome the problems of Hawthorne effects better than using a single method such as controlled trials.
Are serum anticonvulsant levels in people with epilepsy appropriately monitored?
Authors: Thapar Ajay , Richens Alan , Roland Martin , Jacoby Ann , Russell Ian , Roberts Chris , Porter Elaine , Wall Sonya 
Published: March 2003

SummaryThe medical care of people with epilepsy has often been described as being poor, although objective markers for the quality of epilepsy care are lacking. This paper describes the results of using a simple quality marker, appropriate measuring of serum anticonvulsant levels, in assessing the quality of epilepsy care. The checking of serum phenytoin levels in certain clinical circumstances is advocated, whereas the checking of serum sodium valproate levels is not generally supported. A total of 1254 people with epilepsy in the community had their medical records examined for evidence of checking of anticonvulsant levels and 1204 of these individuals completed questionnaires about their epilepsy and its treatment. Of those on phenytoin, only 26% to 47% had phenytoin levels checked appropriately; 23% of patients on sodium valproate were inappropriately having their serum levels checked. The only clinical or organizational factor that predicted whether checking of serum phenytoin levels was performed was whether or not patients reported three common phenytoin side‐effects but this still showed a small effect size (odds ratio 2.4).
Problems in using health survey questionnaires in older patients with physical disabilities. The reliability and validity of the SF‐36 and the effect of cognitive impairment
Authors: Seymour D. Gwyn , Ball Anne E. , Russell Elizabeth M. , Primrose William R. , Garratt Andrew M. , Crawford John R. 
Published: March 2003

AbstractReliability and validity of the SF‐36 Health Survey Questionnaire was assessed in older rehabilitation patients, comparing cognitively impaired with cognitively normal subjects. The SF‐36 was administered by face‐to‐face interview to 314 patients (58–93 years) in the day hospital and rehabilitation wards of a department of medicine for the elderly. Reliability was measured using Cronbach’s alpha (for internal consistency) on the main sample and intraclass correlation coefficients on a test–retest sample; correlations with functional independence measure (FIM) were examined to assess validity. In 203 cognitively normal patients (Mini‐Mental State Examination ≥24), Cronbach’s alpha scores on the eight dimensions of the SF‐36 ranged from 0.545 (social function) to 0.933 (bodily pain). The range for the 111 cognitively impaired patients was 0.413–0.861. Cronbach’s alpha values were significantly higher (i.e. reliability was better) in the cognitively normal group for bodily pain (P = 0.003), mental health (P = 0.03) and role emotional (P = 0.04). In test–retest studies on a further 67 patients, an intraclass correlation coefficient of 0.7 was attained for five out of eight dimensions in cognitively normal patients, and four out of eight dimensions in the cognitively impaired. Only the physical function dimension in the cognitively normal group attained the criterion level (r > 0.4) for construct validity when correlated with the FIM. In this group of older physically disabled patients, levels of reliability and validity previously reported for the SF‐36 in younger subjects were not attained, even on face‐to‐face testing. Patients with coexistent cognitive impairment performed worse than those who were cognitively normal.
Aeromonas hydrophila causes ‘black disease' in fairy shrimps (Anostraca; Crustacea)
Authors: Dierckens  , Vandenberghe  , Beladjal  , Huys  , Mertens  , Swings  
Published: March 2003

AbstractA total of 51 bacterial strains were isolated from fairy shrimps [Branchipus schaefferi (Fisher), Chirocephalus diaphanus (Prévost) and Streptocephalus torvicornis (Waga)] showing signs of ‘black disease'. The fairy shrimps showed black nodules on the thoracic appendages, the cercopods, the antennae and sometimes at the back of the head. The infection sites on the thoracic appendages were restricted to the proximal parts of the endopodite, the exopodite and endite I. In order to check Koch's postulates, pure bacterial cultures were administered to healthy fairy shrimps. One bacterial pathogen was identified as Aeromonas hydrophila using BIOLOG and the genotypic fingerprinting technique AFLP.
Reliability of a nutrition screening tool for use in elderly day hospitals
Authors: Mackintosh M. A. , Hankey C. R. 
Published: March 2003

BackgroundThere are a plethora of nutrition screening tools (NSTs) in use in a variety of clinical settings that are either unvalidated and/or not client specific. There is a need for an NST for all elderly patients attending community day hospitals. At present such a validated tool is unavailable.AimsTo assess the reliability and reproducibility of a developed NST; and to identify elderly patients attending day hospitals who have, or are at risk of, poor nutritional status.MethodsThree day hospitals were selected and 70 admissions were prospectively assessed by Nursing staff and independently by a State Registered Dietitian (SRD) The patients’ nutritional status was anthropometrically assessed using the NST.ResultsThe level of agreement between the nurse and the dietitian for each of the levels of the NST and the overall score was either ‘good agreement’ or ‘very good agreement’ as defined by Cohen’s Kappa. Spearman’s Rank Correlation between objective markers of assessment and the Nurse or Dietitian score from the NST were all statistically significant (P=0.42). As an identifier of risk, the NST has low levels of sensitivity, but high levels of specificity.ConclusionThe Ayrshire NST is a reliable and valid tool which can be used by qualified Nursing staff to assist in screening elderly patients at high risk of poor nutritional status.