bluuebunny/crossref_metadata_2025_split huggingface dataset:
Long‐term effects of changes in goose grazing intensity on arrowgrass populations: a spatially explicit model
Authors: Mulder Christa P.H. , Ruess R.W. 
Published: March 2003

Summary

Field studies on effects of geese on arrowgrass (Triglochin palustris) on the Yukon‐Kuskokwim Delta (SW Alaska) have demonstrated that Pacific black brant geese (Brant bernicla nigricans) can have both positive and negative effects on arrowgrass populations, but cannot predict unambiguously the effects of increased goose numbers on arrowgrass demography.
A cellular automata model was used to predict effects of changes in goose grazing intensity on small‐scale (within‐patch) arrowgrass dynamics. We examined effects of making some of the plant competitors edible to geese, of goose faeces increasing arrowgrass reproduction but reducing size of ungrazed arrowgrass, and of the presence of other species protecting arrowgrass from grazing. We also compared the effects of a random vs. patchy distribution of geese, and of incorporating threshold numbers of arrowgrass below which grazing ceased.
The results indicate that arrowgrass populations are likely to be highest at medium to high levels of grazing. Inclusion of edible competitors and positive effects of faecal deposition resulted in greater changes in arrowgrass population dynamics than did inclusion of associative refuges.
For a given grazing intensity, models generally resulted in lower arrowgrass populations with increased aggregation if distributions of geese were patchy, suggesting that decreased colonization may result from lower dispersal.
Inclusion of a feedback effect (grazing only above a certain plant population) caused arrowgrass populations to persist for much longer. Temporal variability in whether plots were grazed (unrelated to arrowgrass numbers) could not account for this result.
The model results suggest that knowledge of both small‐scale and large‐scale foraging behaviour is needed to predict the long‐term effects of goose grazing on arrowgrass. Small‐scale effects on the population may be particularly important where dispersal distances are short. The ability of plant populations to persist locally may be increased if grazing is suspended when herbivory reduces forage plants below a threshold level.
The effects of seed predators on the recruitment of mangroves
Authors: Clarke Peter J. , Kerrigan Raelee A. 
Published: March 2003

Summary

Propagule (diaspore) predation by crabs has been shown to be a major source of mortality for mangroves. We measured predation by crabs on seeds of nine tropical mangrove species in multifactorial experiments by following the fates of tethered propagules.
We tested whether planting, intertidal position and canopy gaps influenced predation of propagules and whether the predation of propagules was reduced in the presence of conspecifics. We also tested if predation influenced patterns of propagule establishment.
Mortality due to predation ranged from 22 to 100%, with Aegiceras corniculatum > Avicennia marina > Bruguiera parviflora > Aegialitis annulata > B. exaristata > Ceriops australis > C. decandra=B. gymnorrhiza > Rhizophora stylosa. Initial predator preference was correlated with the size of propagules.
Propagule planting (prone vs. implanted) and canopy type had the largest magnitude of effects across all species for treatment effects. Propagules dispersed in the prone position had more mortality while those dispersed into canopy gaps were generally less preyed upon. Three species were tested for dominance‐predation by regression of stand relative density with final predation by crabs for canopy treatments. No species had significant effects that supported the hypothesis.
Predation by crabs often changed with intertidal position but showed no consistent pattern among species or gap treatments. Interactions of canopy treatment and tidal position showed that predation by crabs did not have a major influence on the zonation of mangroves in our study sites.
Analyses of covariance of predation and establishment showed that establishment success is strongly controlled by predation in six of the nine species tested. This suggests that herbivores have a greater impact on recruitment than do microhabitat effects on resources. The combined effects of predator refuge and growth preference enhance recruitment in large canopy gaps. Crab predators appear to maintain the floristic similarity between canopy gaps and surrounding forests in tropical mangrove forests of northern Australia by removing allopatric species from gaps.
Stress tolerance of rare and common moss species in relation to their occupied environments and asexual dispersal potential
Authors: Cleavitt Natalie L. 
Published: March 2003

SummarySpecies rarity in mosses may be linked to narrow physiological tolerance and habitat specificity of established colonies and gametophyte fragments (i.e. fragments of stem apices). Stress tolerance and habitat light and moisture were compared for three rare and three common moss species.Observed habitat specificity was more likely to correspond to physiology in the common species. In particular, one common species,Mnium spinulosum, was limited by intolerance of high light conditions and is characteristic of deeply shaded conifer stands, while another,Bryum pseudotriquetrum, lacked desiccation tolerance and is typical of moist areas such as stream banks. However, the rare species,Mielichhoferia macrocarpa, which occurred in the darkest and wettest sites was not intolerant of high light or desiccation.The relationship between desiccation tolerance and habitat moisture (based on a mesic to xeric scale) was less clear than in prior bryophyte studies, suggesting that a more rigorous quantification of habitat moisture is needed.Contrary to predictions, the rare species did not have narrower physiological tolerances than the common species. The match between environment and physiology for common species probably results from their occupation of more of the potentially suitable sites.There may also be selection for broader physiological tolerance in rare species resulting from their greater reliance on asexual reproduction, which might explain their relatively high desiccation tolerance both as colonies and fragments.
Experimental derivation of functions relating growth ofArabidopsis thalianato neighbour size and distance
Authors: Purves D. W. , Law R. 
Published: March 2003

SummaryA dynamic competition kernel for a plant growing in the presence of a neighbour is a function describing how the competitive effect experienced by the plant depends on its own size, and the size of and distance to a neighbour. Competition experiments onArabidopsis thalianawere used to derive dynamic competition kernels for this species.The experiments entailed growing target plants in isolation, and with single neighbours of different relative sizes, and at different distances. Growth was determined from repeated measures of the area occupied by each plant. Target plants with smaller neighbours, or with neighbours that were further away, grew to a larger size than targets with larger, or closer, neighbours.Relative growth rate (RGR) of isolated plants was best described by the Gompertz equation, a standard plant growth equation that reducesRGRin proportion to the logarithm of plant size.Competition kernels were constructed by modifying the Gompertz equation to include the competitive effect of a neighbour. Alternative kernels (including the zone of influence model), with and without a parameter of asymmetry of competition, were constructed from observed growth rates of target plants with neighbours over short time intervals. The kernels were evaluated based on their ability to predict the size of targets and neighbours over a much longer time period.The kernel that best described growth overall was a simple function proportional to the logarithm of neighbour size, and decreasing with distance to the neighbour. The zone of influence model was best able to describe the effects of distance on competition, but was relatively unsuccessful when the two plants differed substantially in size. Including a parameter for asymmetry did not provide any notable improvements in predictive ability, and in many cases made the predictions worse.
Telephone reporting in the consultant–generalist relationship
Authors: DO Thomas A. Haldis , MD James C. Blankenship 
Published: March 2003

Abstract Rationale, aims and objectives The aim of this paper is to examine the issue
of telephone reporting by consultants in the medical community, which is rarely used
in medicine today. Methods The paper reviews principal publications addressing
this field that have shown that communication between consultants and primary care
physicians has many shortcomings, frequently leaving the primary care physician with
unanswered questions. Discussion and conclusions We present the value of routine telephone reporting by consultants to their primary care counterparts and also discuss possible future implications of communication via electronic mail.
Investigation of within‐study selective reporting in clinical research: follow‐up of applications submitted to a local research ethics committee
Authors: Hahn S. , Williamson P. R. , Hutton J. L. 
Published: March 2003

Abstract Rationale, aims and objectives Within‐study selective reporting is widely believed to exist, although to date there have been no empirical studies to assess the extent of the problem in clinical research. The present study aimed to examine this process. Methods We undertook a pilot study, involving a single local research ethics committee (LREC), in which we compared the outcomes, analysis and sample size proposed in the original approved study protocol with the results presented in the subsequent study report. Results We received 41 (73%) replies from lead researchers of 56 projects, which were a complete cohort of clinical research applications approved in a particular time period by the LREC. Fifteen of these projects, which were completed and published at the time of our study, were further investigated. Only six (40%) stated which outcome variables were of primary interest and four (67%) of these showed consistency in the reports. Eight (53%) of the 15 studies mentioned an analysis plan. However, seven (88%) of these eight studies did not follow their prescribed analysis plan: the analysis of outcome variables or associations between certain variables were found to be missing from the report. Conclusions Our pilot study has shown that within‐study selective reporting may be examined qualitatively by comparing the study report with the study protocol. Our results suggest that it might well be substantial; however, the bias can only be broadly identified as protocols are not sufficiently precise.
Bayeswatch: an overview of Bayesian statistics
Authors: Austin Peter C. , Brunner Lawrence J. , Hux MD SM Janet E. 
Published: March 2003

AbstractIncreasingly, clinical research is evaluated on the quality of its statistical analysis. Traditionally, statistical analyses in clinical research have been carried out from a ‘frequentist’ perspective. The presence of an alternative paradigm – the Bayesian paradigm – has been relatively unknown in clinical research until recently. There is currently a growing interest in the use of Bayesian statistics in health care research. This is due both to a growing realization of the limitations of frequentist methods and to the ability of Bayesian methods explicitly to incorporate prior expert knowledge and belief into the analyses. This is in contrast to frequentist methods, where prior experience and beliefs tend to be incorporated into the analyses in an ad hoc fashion. This paper outlines the frequentist and Bayesian paradigms. Acute myocardial infarction mortality data are then analysed from both a Bayesian and a frequentist perspective. In some analyses, the two methods are seen to produce comparable results; in others, they produce different results. It is noted that in this example, there are clinically relevant questions that are more easily addressed from a Bayesian perspective. Finally, areas in clinical research where Bayesian ideas are increasingly common are highlighted.
Reflexivity and metapositions: strategies for appraisal of clinical evidence
Authors: Malterud Kirsti 
Published: March 2003

AbstractAccording to Sackett, evidence‐based medicine is the conscientious, explicit and judicious use of current best evidence in making decisions about the care of the individual patient. In this article, clinical reasoning is depicted as multilayered processes of evidence construction by means of social interaction and human interpretation. A basic set of knowledge is the doctor’s initial capital at the onset of the individual encounter. This is a necessary, but insufficient, presumption for the elaboration of clinical knowledge required to solve the particular problem. A diagnostic conclusion may appear to constitute the most obvious part of knowledge. Yet the formulation of hypotheses and the choice of adequate strategies for the pursuit of evidence are perhaps even more significant dimensions of clinical knowledge. Potential biases affect the ways in which evidence is gathered and used. When clinicians are not committed to appraising the evidence constituting the foundations of their enterprise, quality assessment of clinical practice becomes casual and unreliable. Reflexivity implies having a self‐conscious account of the production of knowledge as it is being produced. From metapositions, critical questions can be asked and sometimes answered. Evidence‐based practice in the original sense requires that doctors reflect upon their own positions as knowers, in the process of situated knowing, where certain rhetorical spaces rule.
Induced resistance in rainbow trout, Oncorhynchus mykiss (Walbaum), to gill disease associated with the microsporidian gill parasite Loma salmonae
Authors: Speare  , Beaman  , Jones  , Markham  , Arsenault  
Published: March 2003

AbstractBranchial xenomas were detected by week 5 and disappeared by week 10 after naive juvenile rainbow trout, held at 14.5 °C, were fed or intubated with Loma salmonae‐infected gill tissue preparations. Upon re‐challenge with L. salmonae, these fish were protected from disease and branchial xenomas did not develop. Branchial xenomas were never detected in naive fish held at 10 °C and exposed to L. salmonae. When these fish were re‐challenged with L. salmonae at 14.5 °C, they were also protected from the disease. Branchial xenomas also developed after naive fish, held at 14.5 °C, were injected intraperitoneally with a semipurified preparation of fresh spores, but generally did not develop after intraperitoneal injection with a preparation of spores subjected to freezing and thawing before use. Fish that had received fresh spores intraperitoneally were completely resistant to disease when re‐challenged via oral delivery of spores, whereas those that had received frozen spores were incompletely, but significantly, protected from disease compared with naive fish. We conclude that infection with L. salmonae induces strong protection towards the disease upon re‐exposure to spores, and that the protection does not depend on the completion of the parasite's life cycle, thus establishing the basis for further research on vaccine development for this disease.
Identification and genetic characterization of yeasts isolated from freshwater prawns, Macrobrachium rosenbergii de Man, in Taiwan
Authors: Lu C C , Tang K F J , Chen S N 
Published: March 2003

AbstractSince 1987, farmers in southern Taiwan have reported significant disease‐related mortalities in freshwater prawns. Most mortalities have occurred during the winter, and usually almost all the adult prawns die within 4–5 days after clinical signs appear. Histopathological studies show that cells in hepatopancreatic ducts and tubules are vacuolized and degenerated. Large numbers of membrane‐bound yeast aggregates are observed in the affected tissues. Two hundred and seventeen yeast isolates were obtained from diseased prawns, pond water and sediments from six areas. DNA restriction fragment length polymorphism (RFLP) was used to analyse the yeast genomes and to categorize them into five groups. Conventional biochemical and metabolic methods were then used to identify the yeasts of each group. The results showed that two strains of Candida sake (I and II), Pichia anomala, Endomyces fibuliger and Candida famata were present. In addition, the RAPD (random amplified polymorphic DNA) method was used to determine their genomic similarities. Two strains (I and II) of C. sake were the most similar (72%). C. sake I appears to be the primary causative agent of disease, based on frequencies of occurrence of the yeasts found in the diseased prawns.
Evaluation of florfenicol in Atlantic salmon, Salmo salar L.: efficacy against furunculosis due to Aeromonas salmonicida and cold water vibriosis due to Vibrio salmonicida
Authors: Nordmo  , Holth Riseth  , Varma  , Sutherland  , Brokken  
Published: March 2003

AbstractTwo replicated controlled trials were conducted to determine the efficacy of florfenicol against Aeromonas salmonicida and Vibrio salmonicida infections in Atlantic salmon, Salmo salar L., smolts kept in 25‰ salt water. Infection with A. salmonicida was treated with florfenicol, oxolinic acid, oxytetracycline, trimethoprim/sulphadiazine or flumequine, whereas the V. salmonicida infection was treated with florfenicol or oxolinic acid only. A. salmonicida infection was induced by the introduction of cohabitant fish previously inoculated intraperitoneally. Medication started simultaneously in all test tanks on the first day of specific mortality among test fish. V. salmonicida infection was induced by intraperitoneal inoculation of all test fish. Medication started 1 day after infection. Medicated feeds were produced by coating the antibacterials on standard feed pellets, and administered twice daily for 10 consecutive days. With the dose used in the present trials, florfenicol was highly effective in reducing specific mortalities due to both infections. It was slightly more effective than oxolinic acid and trimethoprim/sulphadiazine against A. salmonicida infection. There was no significant difference between florfenicol and oxolinic acid in reducing specific mortalities due to V. salmonicida.
Alterations in iron, zinc and major plasma proteins of rainbow trout, Oncorhynchus mykiss (Walbaum), and brook trout, Salvelinus fontinalis (Mitchill), with sterile peritonitis induced by oil‐adjuvanted multivalent bacterin vaccination
Authors: Simko E. , El‐Mowafi A. , Bettger W. J. , Ostland V. E. , Ferguson H. W. , Hayes M. A. 
Published: March 2003

AbstractThe early humoral responses of rainbow trout, Oncorhynchus mykiss (Walbaum), and brook trout, Salvelinus fontinalis (Mitchill), with sterile inflammation induced by intraperitoneal Lipogen Triple vaccination were compared to determine if genetic differences in susceptibility to furunculosis in salmonids correlated with different acute phase responses to vaccination. Similar severe acute sterile peritonitis occurred in response to Lipogen Triple in both species. Both species also had a rapid transient reduction in plasma iron concentration at 3 days. Moderate hypoferraemia persisted to day 14 in brook trout, but returned to normal by day 7 in rainbow trout. Plasma zinc decreased sharply 3 days after vaccination in rainbow trout and returned nearly to control levels by day 10; however, plasma zinc did not change in brook trout. Two‐dimensional sodium dodecyl sulphate polyacrylamide electrophoresis of plasma proteins revealed that increased amounts of a 48‐kDa protein group coincided with the hypoferraemic response in rainbow trout. In addition, a modest elevation in a 16‐kDa protein group also occurred in rainbow trout. These studies demonstrated the rapid changes in plasma iron in both species and mild elevation of two putative acute phase plasma proteins associated with vaccine‐induced inflammation in rainbow trout.
Atypical Aeromonas salmonicida infection in naturally and experimentally infected cod, Gadus morhua L.
Authors: Magnadóttir B , Bambir S H , Gudmundsdóttir B K , Pilström L , Helgason S 
Published: March 2003

AbstractCod, Gadus morhua L., of wild origin, were reared at different temperatures for 12 months. During this period, moribund and newly dead fish were examined and samples collected for bacteriology and histopathology. Atypical Aeromonas salmonicida was isolated from 10 individuals reared at or above 7 °C. The isolates were homogeneous with respect to biochemical and antibiogram characters and similar to the ssp. achromogenes National Collection of Industrial and Marine Bacteria, UK, type strain 1110 and reference strains that have been isolated from salmonids and haddock in Iceland. Histopathological analysis of the naturally infected cod showed typical ulceration associated with atypical A. salmonicida infection and also widespread granulomatous formations. One‐year‐old cod of farmed origin, kept at 9 °C, received intraperitoneal or intramuscular injection with different doses of atypical A. salmonicida, isolated from the above wild cod. Mortalities were monitored for 28 days and the LD50 calculated. The route of bacterial injection influenced the mortality rate and LD50 value and affected, to some extent, the pathological changes observed and humoral immune parameters. Pathological changes, including haemorrhage, early stages of granuloma formation and necrotic changes, were seen in several organs. Infection appeared to induce non‐specific antibody activity against trinitrophenyl (TNP)‐haptenated protein and may have activated the complement system. Specific antibody response against atypical A. salmonicida was not detected.
Morphological and molecular biological studies on intramuscular Myxobolus spp. of cyprinid fish
Authors: Molnár K , Eszterbauer E , Székely C , Dán Á , Harrach B 
Published: March 2003

AbstractThe validity of Myxobolus species infecting the skeletal muscles of six cyprinid fish species was studied by morphological and molecular biological methods. Intracellularly developing Myxobolus spores identified as M. cyprini from the common carp, M. musculi from the barbel, and M. pseudodispar from the roach, rudd, common bream and white bream were very similar in their shape and size. Nonetheless, in species identified as M. pseudodispar, the occurrence of spores with an asymmetrical shape was higher than in M. cyprini, while asymmetrical spores were only occasionally found in M. musculi. The DNA sequence analysis of the polymerase chain reaction (PCR)‐amplified 18S rRNA gene of Myxobolus spores from these fish showed a similar phylogeny to that of their host species. As morphological studies and DNA sequence analysis demonstrated slight but real differences in the spores infecting muscles of the six cyprinid species, it is suggested that M. musculi, M. pseudodispar and M. cyprini are valid species.