1,370 research outputs found

    Spatial Characteristics of Water Spray Formed by Two Impinging Jets at Several Jet Velocities in Quiescent Air

    Get PDF
    The spatial characteristics of a spray formed by two impinging water jets in quiescent air were studied over a range of nominal jet velocities of 30 to 74 feet per second. The total included angle between the 0.089-inch jets was 90 deg. The jet velocity, spray velocity, disappearance of the ligaments just before drop formation, mass distribution, and size and position of the largest drops were measured in a circumferential survey around the point of jet impingement. Photographic techniques were used in the evaluations. The distance from the point of jet impingement to ligament breakup into drops was about 4 inches on the spray axis and about 1.3 inches in the radial position +/-90 deg from the axis. The distance tended to increase slightly with increase in jet velocity. The spray velocity varied from about 99 to about 72 percent of the jet velocity for a change in circumferential position from the spray axis to the +/-80 deg positions. The percentages tended to increase slightly with an increase in jet velocity. Fifty percent of the mass was distributed about the spray axis in an included angle of slightly less than 40 deg. The effect of jet velocity was small. The largest observed drops (2260-micron or 0.090-in. diam.) were found on and about the spray axis. The size of the largest drops decreased for an increase in radial angular position, being about 1860 microns (0.074 in.) at the +/-90 deg positions. The largest drop sizes tended to decrease for an increase in jet velocity, although the velocity effect was small. A drop-size distribution analysis indicated a mass mean drop size equal to 54 percent of an extrapolated maximum drop size

    Insensitivity of alkenone carbon isotopes to atmospheric CO<sub>2</sub> at low to moderate CO<sub>2</sub> levels

    Get PDF
    Atmospheric pCO2 is a critical component of the global carbon system and is considered to be the major control of Earth’s past, present and future climate. Accurate and precise reconstructions of its concentration through geological time are, therefore, crucial to our understanding of the Earth system. Ice core records document pCO2 for the past 800 kyrs, but at no point during this interval were CO2 levels higher than today. Interpretation of older pCO2 has been hampered by discrepancies during some time intervals between two of the main ocean-based proxy methods used to reconstruct pCO2: the carbon isotope fractionation that occurs during photosynthesis as recorded by haptophyte biomarkers (alkenones) and the boron isotope composition (Ξ΄11B) of foraminifer shells. Here we present alkenone and Ξ΄11B-based pCO2 reconstructions generated from the same samples from the Plio-Pleistocene at ODP Site 999 across a glacial-interglacial cycle. We find a muted response to pCO2 in the alkenone record compared to contemporaneous ice core and Ξ΄11B records, suggesting caution in the interpretation of alkenone-based records at low pCO2 levels. This is possibly caused by the physiology of CO2 uptake in the haptophytes. Our new understanding resolves some of the inconsistencies between the proxies and highlights that caution may be required when interpreting alkenone-based reconstructions of pCO2

    We are playing football: Seeing the game on Panapompom, PNG

    Get PDF
    Β© Royal Anthropological Institute 2011.This article is about football, played by men from Panapompom in Papua New Guinea's Milne Bay province. Football is problematic not because it is culturally appropriated or modified, but rather because Panapompom desired accurately to reproduce the appearance of the international game. As such it questions conventional frames of reference. An interpretation in terms of culture obscures Panapompom interests in football: its globally recognizable character. It mattered profoundly that Panapompom people played football. Yet framing football as a universal sporting institution is equally inadequate, erasing the specific political project that was embedded in the game. Displacing the interpretative framings, I argue that football itself provides a context in which Panapompom people can judge themselves in relation to others, who are defined in terms of colonial and postcolonial discourses on β€˜development’. Taking football as a contextualizing image, Panapompom people appear in distinctive ways in the field of relationships that it defines.ESR

    Annotating patient clinical records with syntactic chunks and named entities: the Harvey corpus

    Get PDF
    The free text notes typed by physicians during patient consultations contain valuable information for the study of disease and treatment. These notes are difficult to process by existing natural language analysis tools since they are highly telegraphic (omitting many words), and contain many spelling mistakes, inconsistencies in punctuation, and non-standard word order. To support information extraction and classification tasks over such text, we describe a de-identified corpus of free text notes, a shallow syntactic and named entity annotation scheme for this kind of text, and an approach to training domain specialists with no linguistic background to annotate the text. Finally, we present a statistical chunking system for such clinical text with a stable learning rate and good accuracy, indicating that the manual annotation is consistent and that the annotation scheme is tractable for machine learning
    • …
    corecore