96 research outputs found

    Post-disturbance haulout behaviour of harbour seals

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    1. The impact of anthropogenic activity associated with the construction of a proposed tidal turbine on harbour seals (Phoca vitulina) was investigated using controlled disturbance trials.2. Trials were conducted by approaching hauled out seals by boat at a speed of five knots until all seals had entered the water. Trials were carried out at a frequency of once every three days when weather permitted and the post disturbance haulout behaviours of the seals were documented. The time taken for numbers to recover to pre-disturbance levels was determined by monitoring haulout sites using time-lapse photography. In addition, seals were tagged with GPS phone tags providing haulout location and at-sea movement data allowing investigation of how disturbance may influence haulout site choice and seal distribution.3. Mean post-disturbance recovery of seals was 52% (95%CI 35-69%) within 30 minutes. However, mean recovery only returned to 94% (95%CI 55-132%) of pre-disturbance levels after four hours.4. Telemetry tagged seals displayed a high degree of haulout site fidelity. Disturbance trials did not have a significant effect on the probability of seals moving to a different haulout site. 5. The results of this study suggest that increased boat activity that causes seals to enter the water at a higher than normal frequency will not cause individuals to relocate to another haulout site. Seals continued to return to the original site despite repeated disturbance trials suggesting that increased boat activity is likely to repeatedly impact on the same seals with the largest effect being to reduce the amount of time available to seals to haul out.6. This study recommends that monitoring effort to mitigate against increased levels of disturbance caused by boat activity need only be on a local scale relative to any proposed development

    Diversity of Pol IV Function Is Defined by Mutations at the Maize rmr7 Locus

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    Mutations affecting the heritable maintenance of epigenetic states in maize identify multiple small RNA biogenesis factors including NRPD1, the largest subunit of the presumed maize Pol IV holoenzyme. Here we show that mutations defining the required to maintain repression7 locus identify a second RNA polymerase subunit related to Arabidopsis NRPD2a, the sole second largest subunit shared between Arabidopsis Pol IV and Pol V. A phylogenetic analysis shows that, in contrast to representative eudicots, grasses have retained duplicate loci capable of producing functional NRPD2-like proteins, which is indicative of increased RNA polymerase diversity in grasses relative to eudicots. Together with comparisons of rmr7 mutant plant phenotypes and their effects on the maintenance of epigenetic states with parallel analyses of NRPD1 defects, our results imply that maize utilizes multiple functional NRPD2-like proteins. Despite the observation that RMR7/NRPD2, like NRPD1, is required for the accumulation of most siRNAs, our data indicate that different Pol IV isoforms play distinct roles in the maintenance of meiotically-heritable epigenetic information in the grasses

    Hemi-Castaing ligamentoplasty for the treatment of chronic lateral ankle instability: a retrospective assessment of outcome

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    Purpose: In the treatment of chronic ankle instability, most non-anatomical reconstructions use the peroneus brevis tendon. This, however, sacrifices the natural ankle stabilising properties of the peroneus brevis muscle. The aim of this study was to evaluate the functional outcome of patients treated with a hemi-Castaing procedure, which uses only half the peroneus brevis tendon. Methods: We performed a retrospective cohort study of patients who underwent hemi-Castaing ligamentoplasty for chronic lateral ankle instability between 1993 and 2010, with a minimum of one year follow-up. Patients were sent a postal questionnaire comprising five validated outcome measures: Olerud-Molander Ankle Score (OMAS), Karlsson Ankle Functional Score (KAFS), Tegner Activity Level Score (pre-injury, prior to surgery, at follow-up), visual analog scale on pain (VAS) and the Short Form 36 (SF-36). Results: Twenty patients completed the questionnaire on functional outcome. The OMAS showed good to excellent outcome in 80% and the KAFS in 65%, the Tegner Score improved from surgery but did not reach pre-injury levels, the VAS on pain was 1 of 10 and the SF-36 returned to normal compared with the average population. Conclusions: Even though most patients were satisfied with the results, outcome at long-term follow-up was less favourable compared with the literature on anatomical reconstructions. In accordance with the literature, we therefore conclude that the initial surgical treatment of chronic lateral ankle instability should be an anatomical repair with augmentation (i.e. the Broström-Gould technique) and the non-anatomical repair should be reserved for unsuccessful cases after anatomical repair or in cases where no adequate ligament remnants are available for reconstruction

    Sensitivity and Bias in Decision-Making under Risk: Evaluating the Perception of Reward, Its Probability and Value

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    BACKGROUND: There are few clinical tools that assess decision-making under risk. Tests that characterize sensitivity and bias in decisions between prospects varying in magnitude and probability of gain may provide insights in conditions with anomalous reward-related behaviour. OBJECTIVE: We designed a simple test of how subjects integrate information about the magnitude and the probability of reward, which can determine discriminative thresholds and choice bias in decisions under risk. DESIGN/METHODS: Twenty subjects were required to choose between two explicitly described prospects, one with higher probability but lower magnitude of reward than the other, with the difference in expected value between the two prospects varying from 3 to 23%. RESULTS: Subjects showed a mean threshold sensitivity of 43% difference in expected value. Regarding choice bias, there was a 'risk premium' of 38%, indicating a tendency to choose higher probability over higher reward. An analysis using prospect theory showed that this risk premium is the predicted outcome of hypothesized non-linearities in the subjective perception of reward value and probability. CONCLUSIONS: This simple test provides a robust measure of discriminative value thresholds and biases in decisions under risk. Prospect theory can also make predictions about decisions when subjective perception of reward or probability is anomalous, as may occur in populations with dopaminergic or striatal dysfunction, such as Parkinson's disease and schizophrenia

    Harbour seal haul-out monitoring, Sound of Islay. Scottish Natural Heritage Commissioned Report No. 894.

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    The purpose of this report is to provide an overview of the current techniques available for monitoring seal haul-out sites either at the Sound of Islay or at haul-out sites elsewhere. This report builds on existing knowledge of harbour seal behaviour in the Sound of Islay and the South-East Islay Skerries SAC based on telemetry data collected in 2011 and 2012 with an assessment of data collected by GPS phone tags deployed in April 2014.Main findings Controlled disturbance trials were carried out to assess the effect of disturbance by increased boat activity on haul-out behaviour. Concurrent monitoring of haul-out sites using remote camera systems recorded behavioural responses to trials, as well as giving daily seal counts at particular sites.Modelling of transition probability indicated that controlled disturbance trials did not affect the probability of harbour seals transiting from one haul-out site to another. Seals generally displayed a high degree of site fidelity. The relationship between site fidelity and transition probability varied with whether seals hauled out again on the same or on a subsequent low tide period after a disturbance. Overall, seals were more likely to transit from one haul-out site to another if the trip in between included at least one high tide period.The results of this study suggest that increased boat activity during the construction phase of the proposed tidal turbine development will not cause individual seals to transit from one haul-out site to another. If seals are flushed from their haulout they are likely to return to the same haul-out site either during the same or on a subsequent low tide period. The recommendation of this report is therefore that monitoring effort to mitigate against any perceived risk of an increase in levels of disturbance by boat need only be on a local scale relative to any proposed development.In light of these results a simple, time lapse photography based method of haulout monitoring that should provide sufficient information to identify and characterise any boat based disturbance events is describe

    Post-disturbance haulout behaviour of harbour seals

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    1.  The impact of anthropogenic activity associated with marine renewable developments on harbour seals (Phoca vitulina) was investigated using controlled disturbance trials. 2.  Hauled‐out seals were approached by boat until all seals had entered the water, and this was repeated approximately every 3 days (weather permitting). The time taken for seal counts to return to pre‐disturbance levels was determined by monitoring haulout sites using time‐lapse photography.3.  Mean post‐disturbance counts of hauled‐out seals returned to 52% (95% confidence interval [CI] 35–69%) of pre‐disturbance counts within 30 min. However, mean counts only returned to 94% (95% CI 55–132%) of pre‐disturbance counts after 4 hr.4.  Eight seals were tagged with Global Positioning System phone tags to provide information on haulout location and at‐sea movements, allowing investigation of how disturbance may influence haulout site choice and seal distribution.5.  Telemetry‐tagged seals displayed a high degree of haulout site fidelity. Disturbance trials did not have a significant effect on the probability of seals moving to a different haulout site.6.  When seals hauled out again within the same low‐tide period after disturbance trials, the proportion of time spent hauled out was high, indicating that when seals are motivated to haul out they will do so despite past disturbance. Motivation to haul out more on disturbance trial days was not linked to a cyclic pattern of hauling out more over consecutive low‐tide periods.7.  As there was no large‐scale redistribution after disturbance, we suggest that monitoring effort to determine the effects of short‐term increases in levels of disturbance caused by boat activity can be spatially localized. However, where disturbance is likely to be longer term or impact on important haulout sites for breeding and/or moulting, monitoring may be required over a larger geographical area
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