Percutaneous left atrial appendage occlusion discrepancy between randomised trials and clinical practice

In patients with atrial fibrillation and previous episodes of bleeding on oral anticoagulant treatment, left atrial appendage occlusion (LAAO) has emerged as an alternative way to decrease the risk of stroke. The use of the procedure has been on the rise, and the news coverage has been dominated by an uncritical acceptance of the benefit of this procedure, which probably have contributed to the increasing number of procedures. This commentary is a presentation and critical appraisal of the available evidence on the efficacy and safety of left atrial appendage closure as stroke prophylaxis. We illustrate that LAAO is supported by limited randomised data risk of serious complications, which we do not believe supports the current widespread use

Efficiency and Merger Gains in The Danish Forestry Extension Service

In Denmark, many small-scale forest owners are affiliated to local district offices of The Danish Forestry Extension Service. Increasing economic pressure has caused a search for more efficiency in the Service, including potential reorganisation. In this paper, the efficiency of the different offices is evaluated using Data Envelopment Analysis (DEA) to approximate their production technology. Furthermore, recent theoretical developments in DEA-analysis are used to assess the gains from a number of potential mergers, and to decompose these gains into those from technological improvements, harmony effects and scale effects. It is found that technological inefficiency is the major source of inefficiency, mergers are only favoured through harmony gains, and for almost all potential mergers the scale effect seems absent or even negative.Data Envelopment Analysis (DEA), efficiency, reorganisation, Teaching/Communication/Extension/Profession,

Source Spectra and Site Response from SWaves of Intermediate-Depth Vrancea (Romania) Earthquakes

Seismograms from 55 intermediate-depth Vrancea earthquakes (M=4.0- 7.1) recorded at 43 stations of an accelerometric network in Romania are used to derive source spectra and site amplification functions from S-waves in the frequency range 0.5-20 Hz with the generalized inversion technique (GIT) (Castro et al., 1990). Attenuation is taken into account using the nonparametric attenuation functions derived by Oth et al. (2008) from the same dataset, and the attenuation-corrected data are then split into source and site contributions. The source spectra follow the ω-2-model (Brune, 1970, 1971) with high corner frequencies and a related Brune stress drop of the order of 100 MPa. The site amplification functions are determined for both horizontal and vertical components separately. Contrary to wide-spread expectation the vertical component shows significant amplification effects at high frequencies. The H/Z ratios determined from the GIT results compare well with H/V ratios computed directly from the S-wave window of the accelerograms (Lermo and Chávez-García, 1993). The basic assumption for the determination of site effects from H/V ratios is that the vertical component is not or only little affected by site effects. For Vrancea earthquakes, this assumption is incorrect and consequently site effects should not be estimated from H/V ratios. The reason for this peculiar fact is the geometry of intermediate-depth seismicity that leads to almost vertical raypaths beneath the stations

Reconciling multiple counterfactuals when evaluating biodiversity conservation impact in social-ecological systems

When evaluating the impact of a biodiversity conservation intervention, a ‘counterfactual’ is needed, as true experimental controls are typically unavailable. Counterfactuals are possible alternative system trajectories in the absence of an intervention and comparing observed outcomes against the chosen counterfactual allows the impact (change attributable to the intervention) to be determined. Since counterfactuals are hypothetical scenarios, and by definition never occur, they must be estimated. Sometimes there may be many plausible counterfactuals, given that they can include multiple drivers of biodiversity change, and be defined on a range of spatial or temporal scales. Here we posit that, by definition, conservation interventions always take place in social-ecological systems (SES; ecological systems integrated with human actors). Evaluating the impact of an intervention within an SES therefore means taking into account the counterfactuals assumed by different human actors. Use of different counterfactuals by different actors will give rise to perceived differences in the impacts of interventions, which may lead to disagreement about its success or the effectiveness of the underlying approach. Despite that there are biophysical biodiversity trends, it is often true that no single counterfactual is definitively the ‘right one’ for conservation assessment, so multiple evaluations of intervention efficacy could be considered justifiable. Therefore, we propose the need to calculate a quantity termed the sum of perceived differences, which captures the range of impact estimates associated with different actors within a given SES. The sum of perceived differences gives some indication how closely actors within an SES agree on the impacts of an intervention. We illustrate the concept of perceived differences using a set of global, national and regional case studies. We discuss options for minimising the sum, drawing upon literatures from conservation science, psychology, behavioural economics, management and finance