1,635 research outputs found

    Staying over-optimistic about the future : uncovering attentional biases to climate change messages

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    There is considerable concern that the public are not getting the message about climate change. One possible explanation is ‘optimism bias’, where individuals overestimate the likelihood of positive events happening to them and underestimate the likelihood of negative events. Evidence from behavioural neuroscience suggest that this bias is underpinned by selective information processing, specifically through a reduced level of neural coding of undesirable information, and an unconscious tendency for optimists to avoid fixating negative information. Here we test how this bias in attention could relate to the processing of climate change messages. Using eye tracking, we found that level of dispositional optimism affected visual fixations on climate change messages. Optimists spent less time (overall dwell time) attending to any arguments about climate changes (either ‘for’ or ‘against’) with substantially shorter individual fixations on aspects of arguments for climate change, i.e. those that reflect the scientific consensus but are bad news. We also found that when asked to summarise what they had read, non-optimists were more likely to frame their recall in terms of the arguments ‘for’ climate change; optimists were significantly more likely to frame it in terms of a debate between two opposing positions. Those highest in dispositional optimism seemeed to have the strongest and most pronounced level of optimism bias when it came to estimating the probability of being personally affected by climate change. We discuss the importance of overcoming this cognitive bias to develop more effective strategies for communicating about climate change

    The Stability study: a protocol for a multicenter randomized clinical trial comparing anterior cruciate ligament reconstruction with and without Lateral Extra-articular Tenodesis in individuals who are at high risk of graft failure

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    BackgroundThe purpose of anterior cruciate ligament reconstruction (ACLR) is to restore stability to the knee. Persistent rotational laxity following ACLR has been correlated with poor outcome and graft failure. We hypothesize that anterolateral complex reconstruction by way of a Modified Lemaire Lateral Extra-articular Tenodesis (LET) in combination with single bundle ACLR would reduce the risk of persistent rotatory laxity in young individuals who are deemed as being at high risk of failure. We will conduct a pragmatic, multicenter, randomized clinical trial comparing standard single bundle hamstring ACLR with combined ACLR and LET.MethodsSix-hundred patients (300 per group) aged 25years or less with an ACL deficient knee that meet two of the following three criteria will be included: 1) Grade 2 pivot shift or greater; 2) Returning to high risk cutting or pivoting sports; 3) Generalized ligamentous laxity. Participants will be seen at 3-months, 6-months, 12-months and 24-months post-operatively. The primary outcome measure is graft failure requiring revision ACLR or symptomatic instability associated with a positive asymmetric pivot shift indicating persistent rotational laxity. Patients will complete secondary outcome measures at each follow-up visit including patient-reported outcome measures, functional and biomechanical testing, and magnetic resonance imaging.DiscussionThis protocol is the first adequately powered randomized clinical trial investigating the effects of augmenting ACLR with an LET in patients at high-risk of graft failure. The successful completion of this trial has the potential to change surgical practice and provide evidence for the role of the LET in ACLR.Trial registrationThe trial is registered at ClinicalTrials.gov: NCT02018354, 23-12-2013

    Multi-Wavelength Variability of the Synchrotron Self-Compton Model for Blazar Emission

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    Motivated by recent reports of strongly correlated radio and X-ray variability in 3C279 (Grandi, etal 1995), we have computed the relative amplitudes of variations in the synchrotron flux at ν\nu and the self-Compton X-ray flux at 1 keV (R(ν)R(\nu)) for a homogeneous sphere of relativistic electrons orbiting in a tangled magnetic field. Relative to synchrotron self-Compton scattering without induced Compton scattering, stimulated scattering reduces the amplitude of R(ν)R(\nu) by as much as an order of magnitude when \tau_T \gtwid 1. When τT\tau_T varies in a fixed magnetic field, RτR_{\tau} increases monotonically from 0.01 at νo\nu_o, the self-absorption turnover frequency, to 0.50.5 at 100νo100 \nu_o. The relative amplitudes of the correlated fluctuations in the radio-mm and X-ray fluxes from 3C279 are consistent with the synchrotron self-Compton model if τT\tau_T varies in a fixed magnetic field and induced Compton scattering is the dominant source of radio opacity. The variation amplitudes are are too small to be produced by the passage of a shock through the synchrotron emission region unless the magnetic field is perpendicular to the shock front.Comment: 21 pages, 4 fig

    On the Reliability of Cross Correlation Function Lag Determinations in Active Galactic Nuclei

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    Many AGN exhibit a highly variable luminosity. Some AGN also show a pronounced time delay between variations seen in their optical continuum and in their emission lines. In effect, the emission lines are light echoes of the continuum. This light travel-time delay provides a characteristic radius of the region producing the emission lines. The cross correlation function (CCF) is the standard tool used to measure the time lag between the continuum and line variations. For the few well-sampled AGN, the lag ranges from 1-100 days, depending upon which line is used and the luminosity of the AGN. In the best sampled AGN, NGC 5548, the H_beta lag shows year-to-year changes, ranging from about 8.7 days to about 22.9 days over a span of 8 years. In this paper it is demonstrated that, in the context of AGN variability studies, the lag estimate using the CCF is biased too low and subject to a large variance. Thus the year-to-year changes of the measured lag in NGC 5548 do not necessarily imply changes in the AGN structure. The bias and large variance are consequences of finite duration sampling and the dominance of long timescale trends in the light curves, not due to noise or irregular sampling. Lag estimates can be substantially improved by removing low frequency power from the light curves prior to computing the CCF.Comment: To appear in the PASP, vol 111, 1999 Nov; 37 pages; 10 figure

    Development of an unbiased statistical method for the analysis of unigenic evolution

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    BACKGROUND: Unigenic evolution is a powerful genetic strategy involving random mutagenesis of a single gene product to delineate functionally important domains of a protein. This method involves selection of variants of the protein which retain function, followed by statistical analysis comparing expected and observed mutation frequencies of each residue. Resultant mutability indices for each residue are averaged across a specified window of codons to identify hypomutable regions of the protein. As originally described, the effect of changes to the length of this averaging window was not fully eludicated. In addition, it was unclear when sufficient functional variants had been examined to conclude that residues conserved in all variants have important functional roles. RESULTS: We demonstrate that the length of averaging window dramatically affects identification of individual hypomutable regions and delineation of region boundaries. Accordingly, we devised a region-independent chi-square analysis that eliminates loss of information incurred during window averaging and removes the arbitrary assignment of window length. We also present a method to estimate the probability that conserved residues have not been mutated simply by chance. In addition, we describe an improved estimation of the expected mutation frequency. CONCLUSION: Overall, these methods significantly extend the analysis of unigenic evolution data over existing methods to allow comprehensive, unbiased identification of domains and possibly even individual residues that are essential for protein function

    Type I Diabetes in Children and Vitamin D

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    Vitamin D deficiency is associated with multiple childhood diseases including type 1 diabetes mellitus (T1DM). T1DM in children is becoming more prevalent, with a 23% increase nationally from 2001 to 2009. Similarly, West Virginia has had an 8.1% increase in children with type 1Diabetes from 2008/2009 to 2010/2011. This article highlights the association between vitamin D and type 1 diabetes and discusses vitamin D’s potential role in the reduction and management of T1DM in children

    The Effects of Periodically Gapped Time Series on Cross-correlation Lag Determinations

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    The three bright TeV blazars Mrk 421, Mrk 501 and PKS 2155-404 are highly variable in synchrotron X-ray emission. In particular, these sources may exhibit variable time lags between flux variations at different X-ray energy bands. However, there are a number of issues that may significantly bias lag determinations. Edelson et al. (2001) recently proposed that the lags on timescales of hours, discovered by ASCA and BeppoSAX, could be an artifact of periodic gaps in the light curves introduced by the Earth occultation every \~1.6 hr. Using Monte Carlo simulations, in this paper we show that the lags over timescales of hours can not be the spurious result of periodic gaps, while periodic gaps indeed introduces uncertainty larger than what present in the evenly sampled data. The results also show that time lag estimates can be substantially improved by using evenly sampled light curves with large lag to bin-size ratio. Furthermore, we consider an XMM-Newton observation without interruptions and re-sample the light curves using the BeppoSAX observing windows, and then repeat the same cross correlation function (CCF) analysis on both the real and fake data. The results also show that periodic gaps in the light curves do not significantly distort the CCF characters, and indeed the CCF peak ranges of the real and fake data overlap. Therefore, the lags discovered by ASCA and BeppoSAX are not due to periodic gaps in the light curves.Comment: 13 pages, 6 figures, accepted for publication in Ap
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