125 research outputs found

    Preserving the palaeoenvironmental record in Drylands: Bioturbation and its significance for luminescence-derived chronologies

    Get PDF
    Luminescence (OSL) dating has revolutionised the understanding of Late Pleistocene dryland activity. However, one of the key assumptions for this sort of palaeoenvironmental work is that sedimentary sequences have been preserved intact, enabling their use as proxy indicators of past changes. This relies on stabilisation or burial soon after deposition and a mechanism to prevent any subsequent re-mobilisation. As well as a dating technique OSL, especially at the single grain level, can be used to gain an insight into post-depositional processes that may distort or invalidate the palaeoenvironmental record of geological sediment sequences. This paper explores the possible impact of bioturbation (the movement of sediment by flora and fauna) on luminescence derived chronologies from Quaternary sedimentary deposits in Texas and Florida (USA) which have both independent radiocarbon chronologies and archaeological evidence. These sites clearly illustrate the ability of bioturbation to rejuvenate ancient weathered sandy bedrock and/or to alter depositional stratigraphies through the processes of exhumation and sub-surface mixing of sediment. The use of multiple OSL replicate measurements is advocated as a strategy for checking for bioturbated sediment. Where significant OSL heterogeneity is found, caution should be taken with the derived OSL ages and further measurements at the single grain level are recommended. Observations from the linear dunes of the Kalahari show them to have no bedding structure and to have OSL heterogeneity similar to that shown from the bioturbated Texan and Florida sites. The Kalahari linear dunes could have therefore undergone hitherto undetected post-depositional sediment disturbance which would have implications for the established OSL chronology for the region

    Effects of dietary Na+ deprivation on epithelial Na+ channel (ENaC), BDNF, and TrkB mRNA expression in the rat tongue

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>In rodents, dietary Na<sup>+ </sup>deprivation reduces gustatory responses of primary taste fibers and central taste neurons to lingual Na<sup>+ </sup>stimulation. However, in the rat taste bud cells Na<sup>+ </sup>deprivation increases the number of amiloride sensitive epithelial Na<sup>+ </sup>channels (ENaC), which are considered as the "receptor" of the Na<sup>+ </sup>component of salt taste. To explore the mechanisms, the expression of the three ENaC subunits (α, ÎČ and Îł) in taste buds were observed from rats fed with diets containing either 0.03% (Na<sup>+ </sup>deprivation) or 1% (control) NaCl for 15 days, by using <it>in situ </it>hybridization and real-time quantitative RT-PCR (qRT-PCR). Since BDNF/TrkB signaling is involved in the neural innervation of taste buds, the effects of Na<sup>+ </sup>deprivation on BDNF and its receptor TrkB expression in the rat taste buds were also examined.</p> <p>Results</p> <p><it>In situ </it>hybridization analysis showed that all three ENaC subunit mRNAs were found in the rat fungiform taste buds and lingual epithelia, but in the vallate and foliate taste buds, only α ENaC mRNA was easily detected, while ÎČ and Îł ENaC mRNAs were much less than those in the fungiform taste buds. Between control and low Na<sup>+ </sup>fed animals, the numbers of taste bud cells expressing α, ÎČ and Îł ENaC subunits were not significantly different in the fungiform, vallate and foliate taste buds, respectively. Similarly, qRT-PCR also indicated that Na<sup>+ </sup>deprivation had no effect on any ENaC subunit expression in the three types of taste buds. However, Na<sup>+ </sup>deprivation reduced BDNF mRNA expression by 50% in the fungiform taste buds, but not in the vallate and foliate taste buds. The expression of TrkB was not different between control and Na<sup>+ </sup>deprived rats, irrespective of the taste papillae type.</p> <p>Conclusion</p> <p>The findings demonstrate that dietary Na<sup>+ </sup>deprivation does not change ENaC mRNA expression in rat taste buds, but reduces BDNF mRNA expression in the fungiform taste buds. Given the roles of BDNF in survival of cells and target innervation, our results suggest that dietary Na<sup>+ </sup>deprivation might lead to a loss of gustatory innervation in the mouse fungiform taste buds.</p

    Functional neuroimaging of visual creativity: a systematic review and meta-analysis

    Get PDF
    Introduction: The generation of creative visual imagery contributes to technological and scientific innovation, and production of visual art. The underlying cognitive and neural processes are however poorly understood. Methods: This review synthesises functional neuroimaging studies of visual creativity. Seven functional magnetic resonance imaging (fMRI) and 19 electroencephalography (EEG) studies were included, comprising 27 experiments and around 800 participants. Results: Activation likelihood estimation meta-analysis of the fMRI studies comparing visual creativity to non-rest control tasks yielded significant clusters in thalamus, left fusiform gyrus, and right middle and inferior frontal gyri. The EEG studies revealed a tendency for decreased alpha power during visual creativity compared to baseline, but comparisons of visual creativity to non-rest control tasks revealed inconsistent findings. Conclusions: The findings are consistent with suggested contributions to visual creativity of prefrontally-mediated inhibition, evaluation and working memory, as well as visual imagery processes. Findings are discussed in relation to prominent theories of the neural basis of creativity

    A Gaseous Argon-Based Near Detector to Enhance the Physics Capabilities of DUNE

    Get PDF
    This document presents the concept and physics case for a magnetized gaseous argon-based detector system (ND-GAr) for the Deep Underground Neutrino Experiment (DUNE) Near Detector. This detector system is required in order for DUNE to reach its full physics potential in the measurement of CP violation and in delivering precision measurements of oscillation parameters. In addition to its critical role in the long-baseline oscillation program, ND-GAr will extend the overall physics program of DUNE. The LBNF high-intensity proton beam will provide a large flux of neutrinos that is sampled by ND-GAr, enabling DUNE to discover new particles and search for new interactions and symmetries beyond those predicted in the Standard Model

    Highly-parallelized simulation of a pixelated LArTPC on a GPU

    Get PDF
    The rapid development of general-purpose computing on graphics processing units (GPGPU) is allowing the implementation of highly-parallelized Monte Carlo simulation chains for particle physics experiments. This technique is particularly suitable for the simulation of a pixelated charge readout for time projection chambers, given the large number of channels that this technology employs. Here we present the first implementation of a full microphysical simulator of a liquid argon time projection chamber (LArTPC) equipped with light readout and pixelated charge readout, developed for the DUNE Near Detector. The software is implemented with an end-to-end set of GPU-optimized algorithms. The algorithms have been written in Python and translated into CUDA kernels using Numba, a just-in-time compiler for a subset of Python and NumPy instructions. The GPU implementation achieves a speed up of four orders of magnitude compared with the equivalent CPU version. The simulation of the current induced on 10^3 pixels takes around 1 ms on the GPU, compared with approximately 10 s on the CPU. The results of the simulation are compared against data from a pixel-readout LArTPC prototype

    Extend Empathy Through Accessibility: Roundtable

    No full text
    This session attempts to address biases in ways of thinking about accessible design, encouraging an understanding of disability and barriers to access through the lens of Universal Design. When course content and experiences are designed with an eye to removing barriers to access versus ad-hoc, time-of-need remediation for individuals, pedagogy can be elevated to a higher standard for all. Creating and selecting accessible course content can introduce new ways of engaging with pedagogy – often in ways faculty may not expect! Embrace the vulnerability that is inherent to accessibility design work, and see your work connect with others more meaningfully and deeply
    • 

    corecore