830 research outputs found

    Perceived Speed of Compound Stimuli Is Moderated by Component Contrast, Not Overall Pattern Contrast

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    The perception of speed is susceptible to manipulations of image contrast, both for simple sine wave and more complex stimuli, such that low-contrast patterns generally appear slower than their high-contrast equivalents. It is not known whether the crucial factor is the contrast of the underlying Fourier components or the contrast of the overall complex pattern. Here, two experiments investigate this issue using compound gratings, comprising two vertical sine wave stimuli with equal contrast, but a 3:1 spatial frequency ratio. Component gratings were summed in ‘‘peaks add’’ and in ‘‘peaks subtract’’ phase, creating conditions with either (a) identical component contrasts, despite differences in overall pattern contrast or (b) differences in component contrasts despite identical overall pattern contrast. Experiment 1 demonstrated that the perceived speed is determined by the contrast of the components regardless of relative phase and hence of overall pattern contrast. Experiment 2 replicated this result while eliminating potential explanations based on differences in spatial frequency content. Along with previous compound grating and plaid studies, the data support a two-stage velocity estimation process involving the derivation of separate speed signals for each Fourier component, followed by integration of these signals across spatial scales

    Language-Naive Chimpanzees (Pan troglodytes) Judge Relations Between Relations in a Conceptual Matching-to-Sample Task

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    Three chimpanzees with a history of conditional and numeric token training spontaneously matched relations between relations under conditions of nondifferential reinforcement. Heretofore, this conceptual ability was demonstrated only in language-trained chimpanzees. The performance levels of the language-naive animals in this study, however, were equivalent to those of a 4th animal—Sarah—whose history included language training and analogical problem solving. There was no evidence that associative factors mediated successful performance in any of the animals. Prior claims of a profound disparity between language-trained and language-naive chimpanzees apparently can be attributed to prior experience with arbitrary tokens consistently associated with abstract relations and not language per se

    Gavestinel does not improve outcome after acute intracerebral hemorrhage: an analysis from the GAIN International and GAIN Americas studies

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    <p><b>Background and Purpose:</b> Glycine Antagonist in Neuroprotection (GAIN) International and GAIN Americas trials were prospectively designed, randomized, placebo-controlled trials of gavestinel, a glycine-site antagonist and putative neuroprotectant drug administered within 6 hours of suspected ischemic or hemorrhagic stroke. Both trials reported that gavestinel was ineffective in ischemic stroke. This analysis reports the results in those with primary intracerebral hemorrhage.</p> <p><b>Methods:</b> The primary hypothesis was that gavestinel treatment did not alter outcome, measured at 3 months by the Barthel Index (BI), from acute intracerebral hemorrhage, based on pooled results from both trials. The BI scores were divided into 3 groups: 95 to 100 (independent), 60 to 90 (assisted independence), and 0 to 55 (dependent) or dead.</p> <p><b>Results:</b> In total, 3450 patients were randomized in GAIN International (N=1804) and GAIN Americas (N=1646). Of these, 571 were ultimately identified to have spontaneous intracerebral hematoma on baseline head computerized tomography scan. The difference in distribution of trichotomized BI scores at 3 months between gavestinel and placebo was not statistically significant (P=0.09). Serious adverse events were reported at similar rates in the 2 treatment groups.</p> <p><b>Conclusions:</b> These observations from the combined GAIN International and GAIN Americas trials suggest that gavestinel is not of substantial benefit or harm to patients with primary intracerebral hemorrhage. These findings are similar to results previously reported in patients with ischemic stroke.</p&gt

    On the Truncated Pareto Distribution with applications

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    The Pareto probability distribution is widely applied in different fields such us finance, physics, hydrology, geology and astronomy. This note deals with an application of the Pareto distribution to astrophysics and more precisely to the statistical analysis of mass of stars and of diameters of asteroids. In particular a comparison between the usual Pareto distribution and its truncated version is presented. Finally a possible physical mechanism that produces Pareto tails for the distribution of the masses of stars is suggested.Comment: 10 pages 6 figure

    Photon mixing in universes with large extra-dimensions

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    In presence of a magnetic field, photons can mix with any particle having a two-photon vertex. In theories with large compact extra-dimensions, there exists a hierachy of massive Kaluza-Klein gravitons that couple to any photon entering a magnetic field. We study this mixing and show that, in comparison with the four dimensional situation where the photon couples only to the massless graviton, the oscillation effect may be enhanced due to the existence of a large number of Kaluza-Klein modes. We give the conditions for such an enhancement and then investigate the cosmological and astrophysical consequences of this phenomenon; we also discuss some laboratory experiments. Axions also couple to photons in the same way; we discuss the effect of the existence of bulk axions in universes with large extra-dimensions. The results can also be applied to neutrino physics with extra-dimensions.Comment: 41 pages, LaTex, 6 figure

    A biophotonic approach to measure pH in small volumes in vitro: quantifiable differences in metabolic flux around the cumulus-oocyte-complex (COC)

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    Unfertilised eggs (oocytes) release chemical biomarkers into the medium surrounding them. This provides an opportunity to monitor cell health and development during assisted reproductive processes if detected in a non-invasive manner. Here we report the measurement of pH using an optical fibre probe, OFP1, in 5 ÎŒL drops of culture medium containing single mouse cumulus-oocyte-complexes (COCs). This allowed for the detection of statistically significant differences in pH between COCs in culture medium with no additives and those incubated with either a chemical (cobalt chloride) or hormonal treatment (follicle stimulating hormone); both of which serve to induce the release of lactic acid into the medium immediately surrounding the COC. Importantly, OFP1 was shown to be cell-safe with no inherent cell toxicity or light-induced phototoxicity indicated by negative DNA damage staining. Pre-measurement photobleaching of the probe reduced fluorescence signal variability, providing improved measurement precision (0.01 - 0.05 pH units) compared to previous studies. This optical technology presents a promising platform for the measurement of pH and the detection of other extracellular biomarkers to assess cell health during assisted reproduction. This article is protected by copyright. All rights reserved.Hanna J. McLennan, Avishkar Saini, Georgina M. Sylvia, Erik P. Schartner, Kylie R. Dunning, Malcolm S. Purdey, Tanya M. Monro, Andrew D. Abell, Jeremy G. Thompso

    The CLIMPACTS synthesis report: An assessment of the effects of climate change and variation in New Zealand using the CLIMPACTS system

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    In the late 1980s, New Zealand undertook the first national assessment of climate change and its possible impacts on the country.The landmark report, reflecting the judgement of scores of national experts, called for greater efforts in building the national research capacity in order to better quantify the range of impacts that could occur in New Zealand from climate change and variability. In response, the collaborative CLIMPACTS Programme was established to provide this capacity. Ten years on from the first national assessment, the present synthesis offers some results from, as well as a demonstration of, the capacity developed by the CLIMPACTS Programme. The purpose of the present document is to provide a summary report from the CLIMPACTS Programme on climate change and its effects on New Zealand.The chapters and their contents are not comprehensive. Rather, they are focused on a specific set of questions, which conform to the particular expertise of the CLIMPACTS Programme members and which employ a limited set of the wide range of tools available within the CLIMPACTS Model. Other important areas such as forests, indigenous ecosystems and pests and diseases are not yet covered

    The Clinical Utility of the Adolescent and Young Adult Psycho-Oncology Screening Tool (AYA-POST): Perspectives of AYA Cancer Patients and Healthcare Professionals

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    Objective: Routine psychosocial screening and assessment of people diagnosed with cancer are crucial to the timely detection of distress and provision of tailored supportive care; however, appropriate screening tools have been lacking for adolescents and young adults (AYAs), who have unique needs and experiences. One exception is the recently validated AYA Psycho-Oncology Screening Tool (AYA-POST) for use with young people aged 15–29 years, which comprises a distress thermometer and age-specific needs assessment. This study investigates the clinical utility of this measure, as well as the subsequent service responsiveness within the Australian Youth Cancer Services. Method: In total, 118 AYAs and 29 healthcare professionals: (HCPs) completed surveys about the clinical utility of the AYA-POST; a subset of 30 AYAs completed a 3-month follow-up survey assessing service responsiveness. Descriptive statistics (frequencies/means) were computed for all items, with chi-square analyses used to explore whether perceived clinical utility varied with AYA age, AYA sex, HCP discipline or HCP length of time using the AYA-POST. Results: Participants’ responses demonstrate high levels of satisfaction with the tool, evidencing its appropriateness, practicability and acceptability. Moreover, the AYA-POST was reported to facilitate communication about psychosocial needs and prompt referrals, indicating good service responsiveness. Ratings of clinical utility did not differ significantly between AYA and HCP groups.Conclusion: This study demonstrates that the AYA-POST is an appropriate tool in the psychosocial screening of AYAs with cancer, facilitating the identification of distress and unique concerns in this population and valuable in triaging and tailoring care for young cancer patients.Pandora Patterson, Fiona E. J. McDonald, Kimberley R. Allison, Helen Bibby, Michael Osborn, Karen Matthews, Ursula M. Sansom-Daly, Kate Thompson, Meg Plaster, and Antoinette Anazod
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