3,648 research outputs found

    Adenosine 5′-triphosphate and its relationship with other mediators that activate pelvic nerve afferent neurons in the rat colorectum

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    Evidence of a role for purinergic signalling in visceral afferents involving P2X2, P2X3 and P2Y1 receptors exists, which appears to be important during inflammation. This study aimed to evaluate the degree of interaction between adenosine 5′-triphosphate (ATP) and other mediators that activate sensory nerves in the colorectum. Recordings from pelvic nerve afferents were made during application of agents to the in-vitro colorectal preparation. Analysis allowed calculation of single unit activity. When applied individually, bradykinin (78%) and 5-hydoxytryptamine (77%) activated the greatest number of neurons, followed by substance P, protons, ATP and capsaicin. Prostaglandin E2 stimulated the least number (54%) and had a longer latency. Seventy-seven percent of all units studied either responded to both ATP and capsaicin or to neither, giving the greatest degree of activity correlation. Five percent of units were activated by all seven agents and no units were activated by a single agent alone. 5-hydroxytryptamine, capsaicin and protons, when co-applied with ATP, increased pelvic nerve activity to a greater degree than the sum of the individual responses. It is concluded that ATP activates pelvic nerve afferents and acts synergistically with protons, capsaicin and 5-hydroxytryptamine. The pattern of neuronal activation suggests that visceral afferents are polymodal but the receptor expression on their terminals is variable

    A determination of the spin-orbit alignment of the anomalously dense planet orbiting HD 149026

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    We report 35 radial velocity measurements of HD 149026 taken with the Keck Telescope. Of these measurements, 15 were made during the transit of the companion planet HD 149026b, which occurred on 2005 June 25. These velocities provide a high-cadence observation of the Rossiter-McLaughlin effect, the shifting of photospheric line profiles that occurs when a planet occults a portion of the rotating stellar surface. We combine these radial velocities with previously published radial velocity and photometric data sets and derive a composite best-fit model for the star-planet system. This model confirms and improves previously published orbital parameters, including the remarkably small planetary radius, the planetary mass, and the orbital inclination, found to be Rp/RJup = 0.718 ± 0.065, Mp/MJup = 0.352 ± 0.025, and I = 86.1° ± 1.4°, respectively. Together the planetary mass and radius determinations imply a mean planetary density of 1.18(-0.30)(+0.38)g cm(-3). The new data also allow for the determination of the angle between the apparent stellar equator and the orbital plane, which we constrain to be λ = -12° ± 15°

    Inter-individual differences in attitude content:Cognition, affect, and attitudes

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    In this chapter, we describe and integrate advances in the study of inter-individual differences in attitude content. Research within this area has addressed how people differ in the extent to which their attitudes are primarily guided by the favorability of their cognitive and affective responses. We begin by describing work that prompted researchers to address this topic and how these individual differences have been measured. We then highlight the implications of individual differences in cognitive and affective content in relation to attitude formation, attitude change, attitude strength, and how individuals perceive and evaluate people, groups, and other attitude objects. Taken together, these lines of research lend support to the argument that people differ in their use of cognitive and affective information as bases for attitudes. We conclude the chapter by addressing new questions that we believe will stimulate further interest in the topic.</p

    Teaching and learning in virtual worlds: is it worth the effort?

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    Educators have been quick to spot the enormous potential afforded by virtual worlds for situated and authentic learning, practising tasks with potentially serious consequences in the real world and for bringing geographically dispersed faculty and students together in the same space (Gee, 2007; Johnson and Levine, 2008). Though this potential has largely been realised, it generally isn’t without cost in terms of lack of institutional buy-in, steep learning curves for all participants, and lack of a sound theoretical framework to support learning activities (Campbell, 2009; Cheal, 2007; Kluge & Riley, 2008). This symposium will explore the affordances and issues associated with teaching and learning in virtual worlds, all the time considering the question: is it worth the effort

    Harry Kesten (1931-2019), a personal and scientific tribute

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    The mathematical achievements of Harry Kesten since the mid-1950s have revolutionized probability theory as a subject in its own right and in its associations with aspects of algebra, analysis, geometry, and statistical physics. Through his personality and scientific ability, he has framed the modern subject to a degree exceeded by no other. The impact of his work and personality is summarised in this memoir.Comment: High resolution photographs are available via the authors' websites. Accepted versio

    Atomic Layer Deposition of Oxide Materials for Passivated Carrier Selective Contact Solar Cells

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    Silicon-based devices have dominated the industrial solar cell marketplace for several decades, thanks to the low bulk defect concentration and technological relevance of silicon substrates. This has led to an oversupply of dopant-diffused homojunction technologies, which suffer from significant performance losses at the metal-silicon contact interface. In response, the research community has developed carrier-selective heterojunction contacts, which separate the metal from the silicon absorber with heavily-doped silicon layers. These novel contacts provide the same asymmetrical conductivity as the diffused junction in the previous generations of silicon solar cells, but with less processing complexity and greater device performance. Still, the silicon based contacts often limit the performance of the heterojunction solar cell due to a lack of transparency, a high resistivity, and often limited processing space. An alternative approach to forming these heterojunction contacts is to use oxide materials, which offer a wider variety of material parameters than doped silicon contacts while offering greater optical transparency. The purpose of this dissertation is demonstrate the implementation of novel oxide-based carrier-selective contacts, deposited by atomic layer deposition, a soft deposition technique that offers greater control and uniformity than other traditional techniques. An overview of the history and current state-of-the-art for silicon photovoltaics is first given, followed by a chapter on solar cell device physics. The following chapters present demonstrations of ALD oxide materials for solar cell passivation, carrier-selectivity, and charge transport. The structure, processing, and properties of these materials are then used to demonstrate the performance of different solar cell devices followed by a forward-looking perspective on the potential of these materials in the industrial solar cell marketplace

    How well would modern-day oceanic property distributions be known with paleoceanographic-like observations?

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    Author Posting. © American Geophysical Union, 2016. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 31 (2016): 472–490, doi:10.1002/2015PA002917.Compilations of paleoceanographic observations for the deep sea now contain a few hundred points along the oceanic margins, mid-ocean ridges, and bathymetric highs, where seawater conditions are indirectly recorded in the chemistry of buried benthic foraminiferal shells. Here we design an idealized experiment to test our predictive ability to reconstruct modern-day seawater properties by considering paleoceanographic-like data. We attempt to reconstruct the known, modern-day global distributions by using a state estimation method that combines a kinematic tracer transport model with observations that have paleoceanographic characteristics. When a modern-like suite of observations (Θ, practical salinity, seawater δ18O, inline image, PO4, NO3, and O2) is used from the sparse paleolocations, the state estimate is consistent with the withheld data at all depths below 1500 m, suggesting that the observational sparsity can be overcome. Physical features, such as the interbasin gradients in deep inline image and the vertical structure of Atlantic inline image, are accurately reconstructed. The state estimation method extracts useful information from the pointwise observations to infer distributions at the largest oceanic scales (at least 10,000 km horizontally and 1500 m vertically) and outperforms a standard optimal interpolation technique even though neither dynamical constraints nor constraints from surface boundary fluxes are used. When the sparse observations are more realistically restricted to the paleoceanographic proxy observations of δ13C, δ18O, and Cd/Ca, however, the large-scale property distributions are no longer recovered coherently. At least three more water mass tracers are likely needed at the core sites in order to accurately reconstruct the large-scale property distributions of the Last Glacial Maximum.NSF Grant Numbers: 1124880, 11254222016-10-0
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