bluuebunny/crossref_metadata_2025_split huggingface dataset:
Severely reduced sexual reproduction in northern populations of a clonal plant, Decodonverticillatus (Lythraceae)
Authors: Dorken Marcel E. , Eckert Christoper G. 
Published: March 2003

Summary

In flowering plants the balance between sexual and clonal, asexual reproduction can vary widely. We quantified variation in sexual reproduction in a tristylous, clonal, aquatic plant, Decodon verticillatus, and investigated the role of ecological and genetic factors in causing this variation.
We surveyed components of sexual fertility and vegetative growth in 28 populations distributed along a 500‐km latitudinal transect in New England, USA. Northerly populations tend to be monomorphic (M) for style length, and probably therefore have reduced sexual reproduction compared with southerly, trimorphic (T) populations.
Compared with T populations (n = 10), M populations (n = 18) exhibited large reductions for all components of sexual reproduction, including flower production, pollen deposition, pollen tube growth, fertilization, fruit set and seeds per fruit. Seven M populations produced no seed at all, and the other 11 very little (mean = 24 vs. 1139 seeds per plant in trimorphic populations). Clonal propagation was also greatly reduced in M populations.
A survey of three polymorphic allozyme loci detected only single, usually heterozygous, genotypes in 15 M populations, whereas all T populations were genotypically diverse. The other three M populations contained three or fewer genotypes and one always predominated. Sexual recruitment is therefore extremely rare.
Comparison of the sexual fertility of M and T populations in a concurrent common glasshouse experiment with our field data revealed that reduced sexual performance in northern M populations is principally due to genetic factors, but is also caused by ecological factors that covary with latitude.
This abrupt shift away from sexual reproduction in populations at the northern periphery of the geographical range in D. verticillatus may greatly limit their evolutionary potential and restrict further northward expansion.
Alternative successional pathways in the Amazon Basin
Authors: Mesquita Rita C.G. , Ickes Kalan , Ganade Gislene , Williamson G. Bruce 
Published: March 2003

Summary

Successional pathways were evaluated in two Amazonian secondary forest communities with different land‐use histories. Sites which had been clearcut without subsequent use were dominated after 6–10 years by the pioneer genus Cecropia (Moraceae), whereas those used for pasture before abandonment were dominated by the pioneer genus Vismia (Clusiaceae).
There were 58 plant families and 300 species identified in Cecropia stands but only 43 families and 147 species were identified in Vismia stands. There were 77 species in common (Sorensen similarity = 0.34).
Differences in species number and composition of recruiting individuals between stand types were significant and were a function of the dominant pioneer genus, stem density, distance from primary forest, and land‐use history. Regeneration under Vismia canopy was dominated by small Vismia individuals (25% of plants < 2 cm basal diameter), whereas regeneration under Cecropia canopy was more diverse and did not include a single young Cecropia.
The number of regenerating plants in both secondary stand types dropped off sharply with distance (5, 25, 50, and 100 m) from primary forest, suggesting that seed dispersal was limiting plant recruitment. Species richness also declined with distance and could be explained by the decline in plant density. Species richness in Cecropia stands increased linearly with plant density, but in Vismia stands the richness increase with density was a decelerating function.
For the central Amazon, secondary succession involves a more rapid return of primary forest species if deforestation is not followed by use as pasture before abandonment.
Extreme flooding events on the Rhine and the survival and distribution of riparian plant species
Authors: Vervuren P. J. A. , Blom C. W. P. M. , De Kroon H. 
Published: March 2003

Summary

Summer floods whose severity is affected by flooding duration, submergence depth and underwater light availability, have a large impact on the zonation of riparian plant species.
We analysed the range and variability of these flooding components in the River Rhine and quantified their effects on the ability of Arrhenatherum elatius, Achillea millefolium, Rumex acetosa and Rumex crispus, to survive periods of submergence under experimental conditions.
Survival characteristics were used to model species’ lower distribution boundaries for extreme and average floods and were compared with the current field distribution. Different light conditions were simulated by implementing three scenarios of suspended load.
Extreme deep Rhine floods are characterized by very low median light transmission levels (i.e. below 0.5%). The largest survival responses in the experiment were observed at such low levels (0.4–3.5 µmol m−2 s−1). Strong effects of light were found in R. crispus and A. millefolium, but responses were weaker in A. elatius and R. acetosa. Submergence depth also affected survival, but not as strongly as light.
For the flood intolerant species (A. millefolium and A. elatius) the average flood was predicted to have little effect on field distributions under normal light conditions. However, their actual field distributions in 2000 corresponded to the predicted lower boundaries in the extreme years. This suggests that extreme years determine the distributions of these species for many years. The suspended load scenarios significantly modified the predicted lower boundaries in both extreme and average years, implying that plant lower distribution limits may be significantly shifted upwards or downwards depending on the suspended load of the river system.
The predicted lower boundaries of the intermediately tolerant R. acetosa and the highly tolerant R. crispus for both extreme and average years were below the actual field distribution in 2000. This suggests that their current distribution is only partly influenced by major flood disturbances and that other factors, either proximate or historical, may play a prominent role.
Decision analysis in evidence‐based decision making
Authors: Tavakoli Manouche , Davies Huw Talfryn Oakley , Thomson Richard 
Published: March 2003

AbstractMany real world decisions have to be made on a limited evidence base, and clinical decisions are at best problematic. We explored some of the reasons why decision making in health care is so complex, and examined how decision analytic techniques might contribute to problem structuring and to implementation of evidence‐based practice. We argued that decision analysis could, to some extent, overcome complexity of decision making by a clear structuring of the problem and a formal analysis of the implications of different decisions. Decision‐analytic techniques can guide the management of individual patients or can be used to address policy questions about the use of treatment for groups of patients. However, decision analysis is not without its criticisms, e.g. problems are narrowly defined, replacing judgement and dehumanizing care, neglect of process utility and lack of primary data to develop decision analytic models. The development of evidence‐based guidelines is a key component of the UK Government’s quality strategy led by the National Institute for Clinical Excellence (NICE). However, the guidelines approach may lead to conflict when assessments of the effectiveness of interventions for individuals (whether or not supported by a formal decision analysis) conflict with the recommendations made by NICE for cost and clinical effectiveness for aggregate groups of patients. Decision analysis may or may not help with this but if guidelines are derived from a decision analysis, then the implications of patient preferences should be made clearer. However, decision analysis‐derived guidelines will make general recommendations that may not be appropriate for all individuals. Nonetheless, decision analysis does make such implications explicit and propose that the guidelines should be supported by some mechanism for determining individual patient preferences. It will now need to consider whether some of NICE resources should be directed beyond evidence‐based guidelines into decision analysis‐derived guidelines and into decision analytical techniques to provide support for clinical and cost effective decision making within the patient‐clinician encounter.
Measuring the quality of clinical audit projects
Authors: Millard Andrew D. 
Published: March 2003

AbstractThe aim of the study was to develop and pilot a scale measuring the quality of audit projects through audit project reports. Statements about clinical audit projects were selected from existing instruments assessing the quality of clinical audit projects to form a Likert scale. Audit facilitators based in Scottish health boards and trusts piloted the scale. The participants were known to have over 2 years of experience of supporting clinical audit. The response at first test was 11 of 14 and at the second test 27 of 46. Audit facilitators tested the draft scale by expressing their strength of agreement or disagreement with each statement for three reports. Validity and reliability were assessed by test – re‐test, item – total, and total – global indicator correlation. Of the 20 statements, 15 had satisfactory correlation with scale totals. Scale totals had good correlation with global indicators. Test – re‐test correlation was modest.The wide range of responses means further research is needed to measure the consistency of audit facilitators' interpretations, perhaps comparing a trained group with an untrained group.There may be a need for a separate scale for reaudits. Educational impact is distinct from project impact generally. It may be more meaningful to treat the selection of projects and aims, methodology and impact separately as subscales and take a project profiling approach rather than attempting to produce a global quality index.
Clinical practice guidelines: when the tool becomes the rule
Authors: Long Michael J. 
Published: March 2003

AbstractThis work provides a critical examination of the use of clinical practice guidelines to measure individual performance. The problems inherent in using a measure of central tendency derived from a distribution of individual performances are addressed, as is the translation of the collectively determined guidelines into a measurement instrument. It is suggested that every process on the distribution of processes used to determine the guideline must be considered equally legitimate representations of the process in question. It is further suggested that to accept as a standard of quality, a particular process simply because there is a minimum of variation between providers, is to ignore the importance of the linkage between process and outcome. The importance of an independent measure of quality based on outcomes is further emphasized by highlighting the tautological nature of analyses that include an input measure, such as nursing hours, in both the dependent variable and the list of independent variables. It is recommended that individual performance be evaluated within the tolerances of the distribution from which they were derived and not be held to some measure of central tendency of that distribution. The alternative is to use the measure of central tendency with plus or minus limits such as one, or more, standard deviations.
Using imprecise probabilities to address the questions of inference and decision in randomized clinical trials
Authors: Gurrin Lyle C. , Sly Peter D. , Burton Paul R. 
Published: March 2003

AbstractRandomized controlled clinical trials play an important role in the development of new medical therapies. There is, however, an ethical issue surrounding the use of randomized treatment allocation when the patient is suffering from a life threatening condition and requires immediate treatment. Such patients can only benefit from the treatment they actually receive and not from the alternative therapy, even if it ultimately proves to be superior. We discuss a novel new way to analyse data from such clinical trials based on the use of the recently developed theory of imprecise probabilities. This work draws an explicit distinction between the related but nevertheless distinct questions ofinferenceanddecisionin clinical trials. The traditional question of scientific interest asks ‘Which treatment offers the greater chance of success?’ and is the primary reason for conducting the clinical trial. The question of decision concerns the welfare of the patients in the clinical trial, asking whether the accumulated evidence favours one treatment over the other to such an extent that the next patient should decline randomization and instead express a preference for one treatment. Consideration of the decision question within the framework of imprecise probabilities leads to a mathematical definition of equipoise and a method for governing the randomization protocol of a clinical trial. This paper describes in detail the protocol for the conduct of clinical trials based on this new method of analysis, which is illustrated in a retrospective analysis of data from a clinical trial comparing the anti‐emetic drugs ondansetron and droperidol in the treatment of postoperative nausea and vomiting. The proposed methodology is compared quantitatively using computer simulation studies with conventional clinical trial designs and is shown to maintain high statistical power with reduced sample sizes, at the expense of a high type I error rate that we argue is irrelevant in some specific circumstances. Particular emphasis is placed on describing the type of medical conditions and treatment comparisons where the new methodology is expected to provide the greatest benefit.
An evaluation of a domiciliary respite service for younger people with dementia
Authors: Parahoo Kader , Campbell Audrey , Scoltock Carol 
Published: March 2003

AbstractRationale, aims and objectives There is a lack of respite services designed specifically for younger people with dementia. There is also a dearth of studies on the evaluation of domiciliary respite services for carers of people with dementia in general. This paper reports on the evaluation of a domiciliary respite service for carers of younger people with dementia, in one area in Northern Ireland, provided by a local branch of the Alzheimer's Society.Methods Using a qualitative approach, eight carers and their families were interviewed in their own homes about their views and expectations of the service, the benefits and problems they experienced, and other issues of relevance to them.Results Overall, they reported great satisfaction with the service. The way they used, and benefited from, the service differed for individuals. Most of them, however, gained respite in the form of help with bathing and dressing the person with dementia. Carers reported that they did not engage in social or recreational activities during the period of respite. Instead they used the respite time to catch up with household chores and shopping.Discussion and conclusions The benefits and concerns can only be understood from the perspectives of carers and in the context of their needs, values, beliefs and traditions. The insight gained can be used to inform future provision of services for this population.
Can safety assurance procedures in the food industry be used to evaluate a medical screening programme? The application of the Hazard Analysis and Critical Control Point system to an antenatal serum screening programme for Down's syndrome. Stage 1: identifying significant hazards
Authors: Derrington M. Clare , Glencross Janet D. , Draper Elizabeth S. , Hsu Ronald T. , Kurinczuk Jennifer J. 
Published: March 2003

AbstractRationale, aims and objectives Routine review of the Leicestershire district antenatal screening programme for Down's syndrome was carried out by its steering group. This raised suspicions that there were problems with the delivery of the programme. The steering group commissioned a project to adapt the Hazard Analysis and Critical Control Point (HACCP) system, as used in the food industry, to investigate this. The HACCP system is a systematic qualitative approach to problem identification and solution taken from the perspective of the production workers. This paper presents the first stage of the process, the hazard analysis.Methods Preliminary work comprised the preparation and verification of a flow diagram of the screening programme. Data about problems (termed hazards) perceived by Leicestershire health care staff delivering the screening programme were collected by observation, interview and telephone. The problems reported were categorized and assessed to identify those of sufficient importance in terms of their consequences or frequency of occurrence to merit the development of control measures. Hazards relating to operational issues were categorized according to the section of the programme to which they related.Results and conclusions A total of 16 categories of hazard were identified. In addition, nine groups of hazards constituting barriers to delivery of the screening programme as a whole were identified. The HACCP process made these hazards explicit. The first stage of the HACCP system proved a useful tool to identify problems experienced delivering a Down's serum screening programme and to assess which were sufficiently serious to require the development of control measures.
In vitro secretion of metallo‐protease (200 kDa) by the pathogenic piscine haemoflagellate, Cryptobia salmositica Katz, and stimulation of protease production by collagen
Authors: Zuo  , Woo  
Published: March 2003

Abstract Cryptobia salmositica cultured in minimum essential medium secreted metallo‐protease, and a significantly higher amount of the protease was found in media supplemented with either type I or type IV collagen. The enhancement of the protease secretion by type I collagen was dose‐dependent. Using haemoglobin (substrate) SDS‐PAGE, the secreted protease was detected as a single clear band (about 200 kDa). The 200 kDa metallo‐protease was also detected on the C. salmositica surface membrane and the amount was increased by incubating the parasite with collagen. Collagen as a specific substrate may enhance the role of the C. salmositica metallo‐protease in the disease process in infected fish.
Experimental oral transmission of largemouth bass virus
Authors: Woodland J E , Brunner C J , Noyes A D , Grizzle J M 
Published: March 2003

AbstractLargemouth bass virus (LMBV) is a recently discovered iridovirus that causes a fatal disease of largemouth bass, Micropterus salmoides (Lacepède). Fish can become infected by waterborne LMBV, but oral transmission of this virus has not been demonstrated previously. Largemouth bass were gavaged with guppies, Poecilia reticulata Peters, which had been injected with LMBV, and then sampled periodically during a 7‐week observation period. The dose of LMBV averaged 105.6 tissue culture infectious doses – 50% cytopathic endpoint (TCID50) per largemouth bass. Five of 24 largemouth bass exposed to LMBV became infected with the virus, but none of the fish had clinical signs typical of LMBV disease. Virus titres in largemouth bass were highest in swim bladder (105.5–9.5 TCID50 g−1) and were 105.2 TCID50 g−1 or lower in cutaneous mucus, head kidney, trunk kidney, spleen, gonad and intestine. These results indicate that LMBV can be transmitted orally to largemouth bass, but further study is needed to determine the factors affecting pathogenicity of the virus.
Effect of fish density and number of infectious fish on the survival of rainbow trout fry, Oncorhynchus mykiss (Walbaum), during epidemics of infectious pancreatic necrosis
Authors: Bebak‐Williams J , McAllister P E , Smith G , Boston R 
Published: March 2003

AbstractTwo laboratory studies compared the effect of fish density and number of infectious fish on characteristics of survival of rainbow trout fry during controlled epidemics of infectious pancreatic necrosis (IPN). Analyses of hazard functions and survivor functions were used to determine whether peak death rate, time at which the peak death rate occurred and probability of survival to the end of the experiment were associated with fish density and number of infectious fish added (i.e. pathogen concentration). When number of infectious fish was low and fish density increased, the peak death rate increased, time of the peak death rate decreased and the probability of survival to the end of the experiment decreased. When number of infectious fish was high, the effect of density diminished. Loglogistic regression of survival data revealed that fish density, number of infectious fish and interaction between these two variables significantly affected time to death from IPN (P < 0.01).
Food, health and eating among single homeless and marginalized people in London
Authors: Evans N. S. , Dowler E. A. 
Published: March 2003

Summary Background: ‘Single homeless’ people are marginalized and largely dependent on voluntary sector organizations for food. The assessment of dietary quality in such groups is particularly difficult, but information is essential in order to improve provision. The aim of this study was to investigate dietary patterns and food sources of day centre and soup run users. Methods: A simple food frequency questionnaire (FFQ) and 24‐h dietary recall were completed on 423 participants (348 males and 75 females) through opportunistic sampling. ‘Rough sleepers’ made up 25% of the sample population, hostel dwellers 19%; other people classed as ‘homeless’ were in squats/bed and breakfast (B & B)/on a friend's floor (12%). Forty‐three per cent of the sample had a flat or bedsit but were using day centres and soup runs because of financial difficulties. The age range was 15–76 years with a median of 34. Results: Only 28% ate vegetables daily; 60% seldom ate fruit, salad, fruit juice or wholemeal products. For men and women diets were high in saturated fat and nonmilk extrinsic sugar. Intakes of nonstarch polysaccharide, vitamins A, C, E, selenium, potassium and zinc were low. In addition, women had low intakes of protein, iron, folic acid, calcium, iodine and magnesium. Seventy per cent said they wanted to improve their diet. Conclusion: The survey showed that the majority of people using day centres and soup runs do not meet current dietary recommendations. This was a reflection of the foods provided and policies to support the work of day centres and soup runs need to address the quality of food available.