61 research outputs found

    Quantifying risk of overharvest when implementation is uncertain

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    1. Sustainable harvest management implies an ability to control harvest rates. This is challenging in systems that have limited control of resources and resource users, which is often the case in small game harvest management. The difference between management strategies and actual harvest bag size (i.e. implementation uncertainty) may be substantial, but few studies have explored this. 2. We investigated how different management strategies and ecosystem variables affected realised harvest of willow ptarmigan (Lagopus lagopus L.) among nine independently managed, state-owned hunting areas in Central and South Norway during 2008–2015. First, we focused our empirical analysis around three response variables of interest: hunting bag (scaled by area), hunting effort (number of hunting days scaled by area) and hunter efficiency (shot birds per hunting day). Akaike information criteria (AIC) guided model selection among candidate GLMMs. Then, we used model-averaged parameter estimating from the statistical models in numerical simulations to explore risk of overharvest due to implementation uncertainty. 3. The most parsimonious model explaining hunting bag included total allowable catch (TAC) and willow ptarmigan density. Hunting effort was explained by number of permits sold and type of quota (daily vs. weekly quota). The most parsimonious model describing hunter efficiency only included the effect of willow ptarmigan density. 4. Our results show that managers have only partial control over harvest rates in this system, and that hunters were relatively more efficient and harvest rates higher at low densities. This effect was present for all management strategy scenarios, including when managers adjusted TAC according to population estimates from monitoring programmes. 5. Synthesis and applications. Quantifying risk of unsustainable harvest rates under different scenarios enables managers to make informed decisions, when dealing with competing objectives of harvest opportunities and sustainability. The substantial risk of high harvest rates at low densities reported here should encourage frequent use of threshold strategies. This study is one of the first approaches for quantifying implementation uncertainty in small game harvest, and shows how estimates from empirical analyses could be used to quantify risk of overharvest.publishedVersionPaid Open Acces

    Climatic forcing and individual heterogeneity in a resident mountain bird : legacy data reveal effects on reproductive strategies

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    Optimization of clutch size and timing of reproduction have substantial effects on lifetime reproductive success in vertebrates, and both individual quality and environmental variation may impact life history strategies. We tested hypotheses related to maternal investment and timing of reproduction, using 17 years (1978–1994) of individual-based life history data on willow ptarmigan (Lagopus l. lagopus, n = 290 breeding females with n = 319 breeding attempts) in central Norway. We analysed whether climatic variation and individual state variables (age and body mass) affected the number of offspring and timing of reproduction, and individual repeatability in strategies. The results suggest that willow ptarmigan share a common optimal clutch size that is largely independent of measured individual states. While we found no clear direct weather effects on clutch size, higher spring temperatures advanced onset of breeding, and early breeding was followed by an increased number of offspring. Warmer springs were positively related to maternal mass, and mass interacted with clutch size in production of hatchlings. Finally, clutch size and timing of reproduction were highly repeatable within individuals, indicating that individual quality guided trade-offs in reproductive effort. Our results demonstrate how climatic forcing and individual heterogeneity in combination influenced life history traits in a resident montane keystone species. trade-offs, state-dependent, clutch size, breeding time, repeatabilitypublishedVersio

    Harvest Regulations and Implementation Uncertainty in Small Game Harvest Management

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    A main challenge in harvest management is to set policies that maximize the probability that management goals are met. While the management cycle includes multiple sources of uncertainty, only some of these has received considerable attention. Currently, there is a large gap in our knowledge about implemention of harvest regulations, and to which extent indirect control methods such as harvest regulations are actually able to regulate harvest in accordance with intended management objectives. In this perspective article, we first summarize and discuss hunting regulations currently used in management of grouse species (Tetraonidae) in Europe and North America. Management models suggested for grouse are most often based on proportional harvest or threshold harvest principles. These models are all built on theoretical principles for sustainable harvesting, and provide in the end an estimate on a total allowable catch. However, implementation uncertainty is rarely examined in empirical or theoretical harvest studies, and few general findings have been reported. Nevertheless, circumstantial evidence suggest that many of the most popular regulations are acting depensatory so that harvest bag sizes is more limited in years (or areas) where game density is high, contrary to general recommendations. A better understanding of the implementation uncertainty related to harvest regulations is crucial in order to establish sustainable management systems. We suggest that scenario tools like Management System Evaluation (MSE) should be more frequently used to examine robustness of currently applied harvest regulations to such implementation uncertainty until more empirical evidence is available

    Drivers and consequences of partial migration in an alpine bird species

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    1. Partial migration, where a portion of the population migrates between win-ter and summer (breeding) areas and the rest remain year- round resident, is a common phenomenon across several taxonomic groups. Several hypotheses have been put forward to explain why some individuals migrate while others stay resident, as well as the fitness consequences of the different strategies. Yet, the drivers and consequences of the decision to migrate or not are poorly understood.2. We used data from radio- tagged female (n= 73) willow ptarmiganLagopus lago-pus in an alpine study area in Central Norway to test if (i) the decision to migrate was dependent on individual state variables (age and body weight), (ii) individu-als repeated migratory decisions between seasons, and (iii) the choice of migra-tory strategy was related to reproductive success.3. Partially supporting our prediction that migratory strategy depends on in-dividual state, we found that juvenile birds with small body sizes were more likely to migrate, whereas large juveniles remained resident. For adult females, we found no relationship between the decision to migrate or stay resident and body weight. We found evidence for high individual repeatability of migratory decision between seasons. Migratory strategy did not explain variation in clutch size or nest fate among individuals, suggesting no direct influence of the chosen strategy on reproductive success.4. Our results indicate that partial migration in willow ptarmigan is related to juve-nile body weight, and that migratory behavior becomes a part of the individual life history as a fixed strategy. Nesting success was not affected by migratory strategy in our study population, but future studies should assess other traits to further test potential fitness consequences. alpine wildlife, eco-evolution, Lagopus lagopus, migrationpublishedVersio

    Thrombus characteristics evaluated by acute optical coherence tomography in ST elevation myocardial Infarction

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    Aims ST elevation myocardial infarction (STEMI) is caused by an occlusive thrombosis of a coronary artery. We wanted to assess if the thrombus can be characterized according to erythrocyte content and age using intravascular optical coherence tomography (OCT) in a clinical setting. Methods and results We performed manual thrombus aspiration in 66 STEMI patients. OCT was done of the thrombus remnants after aspiration. A light intensity ratio was measured through the thrombus. Forty two of the aspirates had thrombus which could be analyzed histomorphologically for analysis of erythrocyte and platelet content, and to determine the age of thrombus as fresh, lytic or organized. There were 11 red, 21 white and 10 mixed thrombi. Furthermore, 36 aspirates had elements of fresh, 7 of lytic and 8 of organized thrombi. There was no correlation between colour and age. OCT appearance could not predict erythrocyte or platelet content. The light intensity ratios were not significantly different in fresh, lytic or organized thrombi. Conclusion OCT could not differentiate between red and white thrombi, nor determine thrombus age.publishedVersio

    Health problems and help-seeking in a nationwide sample of operational Norwegian ambulance personnel

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    Background To estimate the prevalence of anxiety and depression symptoms, and their association with professional help-seeking, among operational ambulance personnel and a general working population, and to study the symptoms of musculoskeletal pain and disturbed sleep among ambulance personnel. Methods The results of a comprehensive nationwide questionnaire survey of operational ambulance personnel (n = 1180) were compared with the findings of a population-based Norwegian health study of working people (n = 31,987). The questionnaire included measures of help-seeking, the Hospital Anxiety and Depression Scale, the Subjective Health Complaints Questionnaire, the Karolinska Sleep Questionnaire and the Need for Recovery after Work Scale. Results Compared with those in the reference population, the mean of level anxiety symptoms in the ambulance sample was lower for men (3.5 vs. 3.9, P < 0.001) and women (4.0 vs. 4.4, P < 0.05), and the mean level of depression symptoms in ambulance workers was lower for men (2.3 vs. 2.8, P < 0.05) but not for women (2.9 vs. 3.1, P = 0.22). A model adjusted for anxiety and depression symptoms indicated that ambulance personnel had lower levels of help-seeking except for seeing a chiropractor (12% vs. 5%, P < 0.01). In the ambulance sample, symptoms of musculoskeletal pain were most consistently associated with help-seeking. In the adjusted model, only symptoms of disturbed sleep were associated with help-seeking from a psychologist/psychiatrist (total sample = 2.3%). Help-seeking was more often reported by women but was largely unaffected by age. Conclusion The assumption that ambulance personnel have more anxiety and depression symptoms than the general working population was not supported. The level of musculoskeletal pain and, accordingly, the level of help-seeking from a chiropractor were higher for ambulance workers. More research should address the physical strains among ambulance personnel

    Percutaneous coronary angioplasty versus coronary artery bypass grafting in treatment of unprotected left main stenosis (NOBLE) : a prospective, randomised, open-label, non-inferiority trial

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    Background Coronary artery bypass grafting (CABG) is the standard treatment for revascularisation in patients with left main coronary artery disease, but use of percutaneous coronary intervention (PCI) for this indication is increasing. We aimed to compare PCI and CABG for treatment of left main coronary artery disease. Methods In this prospective, randomised, open-label, non-inferiority trial, patients with left main coronary artery disease were enrolled in 36 centres in northern Europe and randomised 1: 1 to treatment with PCI or CABG. Eligible patients had stable angina pectoris, unstable angina pectoris, or non-ST-elevation myocardial infarction. Exclusion criteria were ST-elevation myocardial infarction within 24 h, being considered too high risk for CABG or PCI, or expected survival of less than 1 year. The primary endpoint was major adverse cardiac or cerebrovascular events (MACCE), a composite of all-cause mortality, non-procedural myocardial infarction, any repeat coronary revascularisation, and stroke. Non-inferiority of PCI to CABG required the lower end of the 95% CI not to exceed a hazard ratio (HR) of 1 . 35 after up to 5 years of follow-up. The intention-to-treat principle was used in the analysis if not specified otherwise. This trial is registered with ClinicalTrials.gov identifier, number NCT01496651. Findings Between Dec 9, 2008, and Jan 21, 2015, 1201 patients were randomly assigned, 598 to PCI and 603 to CABG, and 592 in each group entered analysis by intention to treat. Kaplan-Meier 5 year estimates of MACCE were 29% for PCI (121 events) and 19% for CABG (81 events), HR 1 . 48 (95% CI 1 . 11-1 . 96), exceeding the limit for non-inferiority, and CABG was significantly better than PCI (p=0 . 0066). As-treated estimates were 28% versus 19% (1 . 55, 1 . 18-2 . 04, p= 0 . 0015). Comparing PCI with CABG, 5 year estimates were 12% versus 9% (1 . 07, 0 . 67-1 . 72, p= 0 . 77) for all-cause mortality, 7% versus 2% (2 . 88, 1 . 40-5 . 90, p= 0 . 0040) for non-procedural myocardial infarction, 16% versus 10% (1 . 50, 1 . 04-2 . 17, p= 0 . 032) for any revascularisation, and 5% versus 2% (2 . 25, 0 . 93-5 . 48, p= 0 . 073) for stroke. Interpretation The findings of this study suggest that CABG might be better than PCI for treatment of left main stem coronary artery disease.Peer reviewe

    Recovery and prognostic value of myocardial strain in ST-segment elevation myocardial infarction patients with a concurrent chronic total occlusion

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    Objectives: Global left ventricular (LV) function is routinely used to assess cardiac function; however, myocardial strain is able to identify more subtle dysfunction. We aimed to determine the recovery and prognostic value of featuring tracking (FT) cardiovascular magnetic resonance (CMR) strain in ST-segment elevation myocardial infarction (STEMI) patients with a concurrent chronic total occlusion (CTO). Methods: In the randomized EXPLORE trial, there was no significant difference in global LV functio

    Aksjeklasser. Begrensninger i bruken i norsk og europeisk regelverk

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    Oppgavens tema er aksjeklasser i norsk rett og lovreguleringen av dette. Oppgaven analyserer også reguleringen av aksjeklasser i EU og konsekvensene for norsk selskapsrett. Problemstillingen for oppgaven er hvilke begrensninger som gjelder for aksjeselskapers bruk av aksjeklasser i norsk rett, bakgrunnen for disse begrensningene og konsekvensene av dem. I tillegg inneholder oppgaven en kvantitativ undersøkelse av hvilke selskaper i Norge som benytter seg av aksjeklasser, en nærmere utredning av hvilke rettigheter og plikter som reguleres ved bruk av aksjeklasser og hva slags aksjeklasser som benytter seg av denne muligheten
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