1,109 research outputs found

    Don't look north through rose tinted spectacles: tensions, struggles and guiding lights in Scotland - a reflection

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    ‘Scotland has been developing a remarkable adult literacy and numeracy strategy….[it is]…..one of the most dynamic and exciting places in the world right now to be an adult literacy or numeracy practitioner’ (‘Why England should look North for inspiration’. Merrifield, J. 2005, pp 21 and 22). Juliet’s and three other articles in the Reflect journal, October 2005, collectively paint a wonderfully rosy picture of policy, strategy and provision north of the border though Juliet herself recognises the ‘frustration, confusion, dissatisfaction and resistance’ (p 22) that inevitably accompany radical change on the scale that Scotland is striving to implement. Whilst not intending to counter the key tenets of these articles, nor to deny the innovative work that is undoubtedly happening, I want to talk about the flip side of this ‘remarkable’ coin; to balance the hype a little and to offer what I see as a more grounded perspective of ALN in the country. I do this because I believe that whilst we justifiably celebrate the ‘moment of opportunity’ (Hamilton, Macrae and Tett, 2001. p 39) we are presented with, if we cannot publicly debate the tensions, contradictions and shortcomings that we encounter in our literacies’ work, we may be in danger of losing the direction, the ideals and ultimately the opportunities that currently excite and spur us forward

    Simulation of transient energy distributions in sub-ns streamer formation

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    Breakdown and streamer formation is simulated in atmospheric pressure nitrogen for a 2D planar electrode system. A PIC code with multigrid potential solver is used to simulate the evolution of the non-equilibrium ionization front on sub-nanosecond timescales. The ion and electron energy distributions are computed, accounting for the inclusion of inelastic scattering of electrons, and collisionally excited metastable production and ionization. Of particular interest is the increased production of metastable and low-energy ions and electrons when the applied field is reversed during the progress of the ionization front, giving insight into the improved species yields in nanosecond pulsed systems

    X - Ray Flares and Their Connection With Prompt Emission in GRBs

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    We use a wavelet technique to investigate the time variations in the light curves from a sample of GRBs detected by Fermi and Swift. We focus primarily on the behavior of the flaring region of Swift-XRT light curves in order to explore connections between variability time scales and pulse parameters (such as rise and decay times, widths, strengths, and separation distributions) and spectral lags. Tight correlations between some of these temporal features suggest a common origin for the production of X-ray flares and the prompt emission.Comment: 7th Huntsville Gamma-Ray Burst Symposium, GRB 2013: paper 15 in eConf Proceedings C130414

    Gamma-Ray Bursts: Temporal Scales and the Bulk Lorentz Factor

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    For a sample of Swift and Fermi GRBs, we show that the minimum variability timescale and the spectral lag of the prompt emission is related to the bulk Lorentz factor in a complex manner: For small Γ\Gamma's, the variability timescale exhibits a shallow (plateau) region. For large Γ\Gamma's, the variability timescale declines steeply as a function of Γ\Gamma (δTΓ4.05±0.64\delta T\propto\Gamma^{-4.05\pm0.64}). Evidence is also presented for an intriguing correlation between the peak times, tp_p, of the afterglow emission and the prompt emission variability timescale.Comment: Accepted for publication in Ap

    The Hurst Exponent of Fermi GRBs

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    Using a wavelet decomposition technique, we have extracted the Hurst exponent for a sample of 46 long and 22 short Gamma-ray bursts (GRBs) detected by the Gamma-ray Burst Monitor (GBM) aboard the Fermi satellite. This exponent is a scaling parameter that provides a measure of long-range behavior in a time series. The mean Hurst exponent for the short GRBs is significantly smaller than that for the long GRBs. The separation may serve as an unbiased criterion for distinguishing short and long GRBs.Comment: Accepted for publication in Monthly Notices of the Royal Astronomical Societ

    Corrections to Gravity due to a Sol Manifold Extra Dimensional Space

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    The corrections to the gravitational potential due to a Sol extra dimensional compact manifold, denoted as MA3M_A^3, are studied. The total spacetime is of the form M4×MA3M^4\times M_A^3. The range of the Sol corrections is investigated and compared to the range of the T3T^3 corrections.Comment: 13 pages, 10 figures, published versio

    Seasonal variation and impact of waste-water lagoons as larval habitat on the population dynamics of Culicoides sonorensis (Diptera:Ceratpogonidae) at two dairy farms in northern California.

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    The Sacramento (northern Central) Valley of California (CA) has a hot Mediterranean climate and a diverse ecological landscape that is impacted extensively by human activities, which include the intensive farming of crops and livestock. Waste-water ponds, marshes, and irrigated fields associated with these agricultural activities provide abundant larval habitats for C. sonorensis midges, in addition to those sites that exist in the natural environment. Within this region, C. sonorensis is an important vector of bluetongue (BTV) and related viruses that adversely affect the international trade and movement of livestock, the economics of livestock production, and animal welfare. To characterize the seasonal dynamics of immature and adult C. sonorensis populations, abundance was monitored intensively on two dairy farms in the Sacramento Valley from August 2012- to July 2013. Adults were sampled every two weeks for 52 weeks by trapping (CDC style traps without light and baited with dry-ice) along N-S and E-W transects on each farm. One farm had large operational waste-water lagoons, whereas the lagoon on the other farm was drained and remained dry during the study. Spring emergence and seasonal abundance of adult C. sonorensis on both farms coincided with rising vernal temperature. Paradoxically, the abundance of midges on the farm without a functioning waste-water lagoon was increased as compared to abundance on the farm with a waste-water lagoon system, indicating that this infrastructure may not serve as the sole, or even the primary larval habitat. Adult midges disappeared from both farms from late November until May; however, low numbers of parous female midges were detected in traps set during daylight in the inter-seasonal winter period. This latter finding is especially critical as it provides a potential mechanism for the "overwintering" of BTV in temperate regions such as northern CA. Precise documentation of temporal changes in the annual abundance and dispersal of Culicoides midges is essential for the creation of models to predict BTV infection of livestock and to develop sound abatement strategies
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