638 research outputs found

    Predicting Understorey VegetationCover from Overstorey Attributes in Two Temperate MountainForests

    Get PDF
    Summary : It is important to develop a predictive understanding for the environmental controls on understorey vegetation, which harbor most of the plant biodiversity and are the source of food and cover for wildlife. Forest succession models (i. e. gap models) representing overstorey dynamics are not commonly linked to mathematical models of understorey dynamics. This is surprising, given that understorey vegetation clearly responds to changes in the overstorey that result in changing light availability. One difficulty may lie in the coarse representation of light regime captured by most gap models. Linkage of overstorey-understorey models might be facilitated if the diameter structure of simulated stands could be used to drive understorey change, as a proxy for light and other influences. The objective of this study was to determine whether understorey vegetation cover can be adequately predicted by variables derived from overstorey diameter structure alone, or if canopy cover and light availability are important, from additional predictors. Field sampling was conducted at a montane and a subalpine study area in the Swiss Alps. We used regression analysis to assess the relative importance of various overstorey predictors for understorey cover and composition. In the subalpine study area, the relative dominance of graminoids increased with increasing light availability, at the expense of forbs. In the montane study area, forb cover increased sharply with increasing light, while graminoid cover remained at low levels. As a result, the relative dominance of graminoid species declined with increasing light levels. This difference is attributed to the presence of Adenostyles alliariae, a tall, large-leaved forb. The effects of changes in the physical environment on plant community composition were thus mediated by interspecific interactions. This makes it difficult to predict overstorey-induced changes in understorey species composition at the level of functional groups. At both study sites, diameter structure variables were found to provide a reasonable approximation of total understorey cover, cover of the more common species, and species richness. Models of understorey community composition often improved (0-31% increased predictive ability) with inclusion of variables representing the light environment. In the context of gap model development, the great complexity associated with improved representation of light availability must be weighed against the relatively low gain in predictive power that is likely to result. We recommend that efforts to include forest understorey dynamics in gap models begin by considering empirical relationships between understorey patterns and overstorey diameter structur

    Activity of meropenem, against Gram-positive bacteria

    Get PDF
    A new carbapenem antibiotic, meropenem, was shown to be active against a large number of Gram-positive bacteria. The drug inhibited penicillinase-positive and -negative, methicillin-susceptible staphylococci equally well. Among the comparative antimicrobials examined, only N-fonnimidoyl-thienamycin (imipenem) was two to four times more active than meropenem. Compared with vancomycin or methicillin, meropenem was 10-20 times more active. Strains of 11 species of streptococci were highly susceptible to meropenem; the geometric mean MICs of the drug for these species ranged from 0.01 to 0.04mg/l. The agent, however, only had moderate activity against Enterococcus faecalis (mean MIC 5mg/l) and Ent. faecium (mean MIC 11.6 mg/l). Among Corynebacterium jeikeium, strains were encountered that showed susceptibility to meropenem but resistance to imipenem and other β-lactams. Strains of other corynebacteria, Rhodococcus equi, Erysopelothrix rhusio-pathiae, Listeria monocytogenes, and Bacillus spp. all were highly susceptible to meropenem (mean MICs 0.04-0.17 mg/l). Although methicillin-resistant staphylo-cocci were inhibited by concentrations of 1-2 mg/l of meropenem in agar dilution tests, such strains showed heteroresistance in population studies, as is typical for all β-lactam antibiotics. In addition, the biochemical correlate of methicillin-resistance, penicillin-binding protein 2′, showed low affinity for meropenem, similar to that for imipenem. Meropenem was as bactericidal as imipenem and comparative bactericidal antimicrobials in killing-curve experiments. Strains of Ent. faecium, C. jeikeium, and L. monocytogenes were killed at a slower rate than streptococci or staphylococc

    Establishing a cost-effective national surveillance system for Bluetongue using scenario tree modelling

    Get PDF
    Vector-borne diseases pose a special challenge to veterinary authorities due to complex and time-consuming surveillance programs taking into account vector habitat. Using stochastic scenario tree modelling, each possible surveillance activity of a future surveillance system can be evaluated with regard to its sensitivity and the expected cost. The overall sensitivity of various potential surveillance systems, composed of different combinations of surveillance activities, is calculated and the proposed surveillance system is optimized with respect to the considered surveillance activities, the sensitivity and the cost. The objective of this project was to use stochastic scenario tree modelling in combination with a simple cost analysis in order to develop the national surveillance system for Bluetongue in Switzerland. This surveillance system was established due to the emerging outbreak of Bluetongue virus serotype 8 (BTV-8) in Northern Europe in 2006. Based on the modelling results, it was decided to implement an improved passive clinical surveillance in cattle and sheep through campaigns in order to increase disease awareness alongside a targeted bulk milk testing strategy in 200 dairy cattle herds located in high-risk areas. The estimated median probability of detection of cases (i.e. sensitivity) of the surveillance system in this combined approach was 96.4%. The evaluation of the prospective national surveillance system predicted that passive clinical surveillance in cattle would provide the highest probability to detect BTV-8 infected animals, followed by passive clinical surveillance in sheep and bulk milk testing of 200 dairy cattle farms in high-risk areas. This approach is also applicable in other countries and to other epidemic diseases

    Project PathoPig—A practical approach to strengthen post mortem analyses and early detection of pig diseases and zoonoses

    Get PDF
    Post mortem examinations are important for early detection and diagnosis of animal diseases and zoonoses. Over the last ten years, the number of necropsies in livestock has decreased considerably in Switzerland. To counteract this decline, the Federal Food Safety and Veterinary Office (FSVO) launched a project in 2014 called PathoPig. The aim is to evaluate the significance of pathologic-anatomical examinations for early detection of pig diseases and to investigate the impact of the findings on the improvement of pig health. Pig producers can participate if at least one of the following criteria is fulfilled: high morbidity and/or high mortality, unusual clinical signs, recurrent problems of unknown aetiology resistant to therapy or increased use of antimicrobials. Accordingly, the veterinarian examines the herd, fills in a standardised anamnesis protocol and submits one to three pigs representing the health problem to a designated pathology laboratory. After post mortem examination, the veterinarian offers specific recommendations to the farmer. Three to six months later, the Swiss Pig Health Service (SPHS) follows up the success of the veterinary recommendations. In 2014, 371 farms submitted pigs for PathoPig. In 84% of these cases, a conclusive diagnosis was obtained. In 56% of the cases, gastrointestinal problems were determined, most often (44%) caused by pathogenic Escherichia coli. In more than 80% of the cases, the animal health status could be improved considerably after the veterinary consultation. Increased post mortem examinations allowed more specific therapeutic treatments and management recommendations. Additionally, an improvement of collaboration between diagnostic laboratories, veterinarians and producers was achieved, thereby strengthening disease awareness and early detection of pig diseases and zoonoses in Switzerland

    Variations in clinical decision-making between cardiologists and cardiac surgeons; a case for management by multidisciplinary teams?

    Get PDF
    OBJECTIVE: To assess variations in decisions to revascularise patients with coronary heart disease between general cardiologists, interventional cardiologists and cardiac surgeons DESIGN: Six cases of coronary heart disease were presented at an open meeting in a standard format including clinical details which might influence the decision to revascularise. Clinicians (n = 53) were then asked to vote using an anonymous electronic system for one of 5 treatment options: medical, surgical (CABG), percutaneous coronary intervention (PCI) or initially medical proceeding to revascularisation if symptoms dictated. Each case was then discussed in an open forum following which clinicians were asked to revote. Differences in treatment preference were compared by chi squared test and agreement between groups and between voting rounds compared using Kappa. RESULTS: Surgeons were more likely to choose surgery as a form of treatment (p = 0.034) while interventional cardiologists were more likely to choose PCI (p = 0.056). There were no significant differences between non-interventional and interventional cardiologists (p = 0.13) in their choice of treatment. There was poor agreement between all clinicians in the first round of voting (Kappa 0.26) but this improved to a moderate level of agreement after open discussion for the second vote (Kappa 0.44). The level of agreement among surgeons (0.15) was less than that for cardiologists (0.34) in Round 1, but was similar in Round 2 (0.45 and 0.45 respectively) CONCLUSION: In this case series, there was poor agreement between cardiac clinical specialists in the choice of treatment offered to patients. Open discussion appeared to improve agreement. These results would support the need for decisions to revascularise to be made by a multidisciplinary panel

    Trading people versus trading time: What is the difference?

    Get PDF
    BACKGROUND: Person trade-off (PTO) elicitations yield different values than standard utility measures, such as time trade-off (TTO) elicitations. Some people believe this difference arises because the PTO captures the importance of distributive principles other than maximizing treatment benefits. We conducted a qualitative study to determine whether people mention considerations related to distributive principles other than QALY-maximization more often in PTO elicitations than in TTO elicitations and whether this could account for the empirical differences. METHODS: 64 members of the general public were randomized to one of three different face-to-face interviews, thinking aloud as they responded to TTO and PTO elicitations. Participants responded to a TTO followed by a PTO elicitation within contexts that compared either: 1) two life-saving treatments; 2) two cure treatments; or 3) a life-saving treatment versus a cure treatment. RESULTS: When people were asked to choose between life-saving treatments, non-maximizing principles were more common with the PTO than the TTO task. Only 5% of participants considered non-maximizing principles as they responded to the TTO elicitation compared to 68% of participants who did so when responding to the PTO elicitation. Non-maximizing principles that emerged included importance of equality of life and a desire to avoid discrimination. However, these principles were less common in the other two contexts. Regardless of context, though, participants were significantly more likely to respond from a societal perspective with the PTO compared to the TTO elicitation. CONCLUSION: When lives are at stake, within the context of a PTO elicitation, people are more likely to consider non-maximizing principles, including the importance of equal access to a life-saving treatment, avoiding prejudice or discrimination, and in rare cases giving treatment priority based purely on the position of being worse-off

    Balancing equity and efficiency in the Dutch basic benefits package using the principle of proportional shortfall

    Get PDF
    Economic evaluations are increasingly used to inform decisions regarding the allocation of scarce health care resources. To systematically incorporate societal preferences into these evaluations, quality-adjusted life year gains could be weighted according to some equity principle, the most suitable of which is a matter of frequent debate. While many countries still struggle with equity concerns for priority setting in health care, the Netherlands has reached a broad consensus to use the concept of proportional shortfall. Our study evaluates the concept and its support in the Dutch health care context. We discuss arguments in the Netherlands for using proportional shortfall and difficulties in transitioning from principle to practice. In doing so, we address universal issues leading to a systematic consideration of equity concerns for priority setting in health care. The article thus has relevance to all countries struggling with the formalization of equity concerns for priority setting

    The Maine Tidal Power Initiative: Transdisciplinary sustainability science research for the responsible development of tidal power

    Get PDF
    The Maine Tidal Power Initiative (MTPI), an interdisciplinary team of engineers, marine scientists, oceanographers, and social scientists, is using a transdisciplinary sustainability science approach to collect biophysical and social data necessary for understanding interactions between human and natural systems in the context of tidal power development in Maine. MTPI offers a unique opportunity to better understand how group structure and process influence outcomes in transdisciplinary sustainability science research. Through extensive participant observation and semi-structured interviews we: (1) describe MTPI’s organizational structure; (2) examine MTPI’s research approach and engagement with stakeholders from different sectors of society (i.e., industry, government, and the local community); and (3) identify challenges and opportunities for involving different disciplinary expertise and diverse stakeholders in transformational sustainability science research. We found that MTPI’s holistic mission, non-hierarchical structure, and iterative stakeholder engagement process led to important benefits and significant challenges. Positive outcomes include knowledge development, a transferable research framework, shared resources, personal reward, and a greater understanding of the local environment and community. Challenges identified include balancing diverse interests and priorities, maintaining engagement, managing stakeholder relationships, and limited resources. Lessons learned from the process of integrative collaborative research in Maine can offer guidance on what should be considered when carrying out similar transdisciplinary sustainability science projects in other research contexts
    • …
    corecore