1,840 research outputs found

    Modelling dielectric charged drop break up using an energy conservation method

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    In the light of experimental evidence a previously published model to predict the charge and mass redistribution when charged dielectric drops break up has been updated. In particular we have taken the dielectric nature of the liquid, the existence of an external electric field and used photographic evidence of drop break up as a basis for geometrical assumptions that are physically realistic. We have assessed the sensitivity of the charge redistribution assumption and the improved model compares well with the recent accurate experimental evidence. The results apply to ratio of quantities of mass and charge, making the model extremely simple and economical to apply to multi-dimensional charged spray computer codes in order to predict evaporating charged sprays accurately

    Drop-charge correlations for polydisperse electrostatically atomized liquid sprays

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    In many applications liquid sprays are atomized using electrostatic methods, and typically these spray plumes containing drops that have a range of diameters. To understand and predict the dynamics of polydisperse electrically charged spray plumes, knowledge of how the electrical charge is distributed amongst the drops is required. This has been achieved by post-processing phase Doppler anemometry data for two electrostatically atomized liquid sprays and fitting the drop diameter-charge correlation to an assumed relationship of form q=ADn, Here q and D are drop charge and diameter and n and A are empirical constants that describe the correlation. Values of n and A were calculated to be 2.1 to 2.9 and 5.8 ×10-5 for a spray of specific charge 1.8 C/m3 and 2.1 to 3.2 and its value of A is 2.5×10-4 for a spray of specific charge 1.2 C/m3. It was found that the mean drop charge, for all drop diameters, for both data-sets, was almost always less than the drop Rayleigh limit. This latter fact gives confidence in the procedure used since no restriction was placed on this parameter during the processing. We also estimate the distribution of drop charge about the mean value and as a function of diameter and suggest that small drops possess higher rms charge levels

    Isolation of polygenic factors controlling bristle score in Drosophila melanogaster

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    Fluorescent probes of the orientation of myosin regulatory light chains in relaxed, rigor, and contracting muscle.

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    The orientation of the light-chain region of myosin heads in relaxed, rigor, and isometrically contracting fibers from rabbit psoas muscle was studied by fluorescence polarization. Cysteine 108 of chicken gizzard myosin regulatory light chain (cgRLC) was covalently modified with iodoacetamidotetramethylrhodamine (iodo-ATR). Native RLC of single glycerinated muscle fibers was exchanged for labeled cgRLC in a low [Mg2+] rigor solution at 30 degrees C. Troponin and troponin C removed in this procedure were replaced. RLC exchange had little effect on active force production. X-ray diffraction showed normal structure in rigor after RLC exchange, but loss of axial and helical order in relaxation. In isolated myofibrils labeled cgRLC was confined to the regions of the sarcomere containing myosin heads. The ATR dipoles showed a preference for orientations perpendicular to the fiber axis, combined with limited nanosecond rotational motion, in all conditions studied. The perpendicular orientation preference was more marked in rigor than in either relaxation or active contraction. Stretching relaxed fibers to sarcomere length 4 microns to eliminate overlap between actin- and myosin-containing filaments had little effect on the orientation preference. There was no change in orientation preference when fibers were put into rigor at sarcomere length 4.0 microns. Qualitatively similar results were obtained with ATR-labeled rabbit skeletal RLC

    Can twitter replace newswire for breaking news?

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    Twitter is often considered to be a useful source of real-time news, potentially replacing newswire for this purpose. But is this true? In this paper, we examine the extent to which news reporting in newswire and Twitter overlap and whether Twitter often reports news faster than traditional newswire providers. In particular, we analyse 77 days worth of tweet and newswire articles with respect to both manually identified major news events and larger volumes of automatically identified news events. Our results indicate that Twitter reports the same events as newswire providers, in addition to a long tail of minor events ignored by mainstream media. However, contrary to popular belief, neither stream leads the other when dealing with major news events, indicating that the value that Twitter can bring in a news setting comes predominantly from increased event coverage, not timeliness of reporting

    Facial creation: using compositing to conceal identity

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    This study focused on the creation of new faces by compositing features from donor face photographs together that provide a way to generate new face identities. However, does the act of compositing conceal the identity of the donor faces? Two applications of these created faces require donor face identities to remain concealed: Covert social media profiles provide a way for investigating authorities to survey online criminal activity and, as such, a false online identity, including face image, is required. Compositing features/face parts from various donor face photographs could be used to generate new face identities. Face donor photographs are also used for the ‘texturing’ of facial depictions to reconstruct an image of how a person might appear. This study investigated whether compositing unknown face features onto known familiar faces (celebrities and lecturers) was sufficient to conceal identity in a face recognition task paradigm. A first experiment manipulated individual features to establish a feature saliency hierarchy. The results of this informed the order of feature replacement for the second experiment, where features were replaced in a compound manner to establish how much of a face needs to be replaced to conceal identity. In line with previous literature, the eyes and hair were found to be highly salient, with the eyebrows and nose the least. As expected, the more features that are replaced, the less likely the face was to be recognised. A theoretical criterion point from old to new identity was found for the combined data (celebrity and lecturer) where replacing at least two features resulted in a significant decrease in recognition. Which feature was being replaced was found to have more of an effect during the middle part of feature replacement, around the criterion point, where the eyes were more important to be replaced than the mouth. Celebrities represented a higher level of familiarity and, therefore, may be a more stringent set of results for practical use, but with less power than the combined data to detect changes. This would suggest that at least three features (half the face) need to be replaced before recognition significantly decreases, especially if this includes the more salient features in the upper half of the face. However, once all six features were replaced, identity was not concealed 100% of the time, signifying that feature replacement alone was not sufficient to conceal identity. It is completely possible that residual configural and contrast information was facilitating recognition, and, therefore, it is likely that manipulations, such as these, are also needed in order to conceal identity

    Motivations for doing interdisciplinary research: Results from an Australian qualitative study

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    While the literature provides a strong conceptual justification for Interdisciplinary Research (for example: Klein 1990, 1996; Sherif & Sherif, 1969) and a number of studies document the benefits and challenges of such studies (such as: Slatin, Galizzi, Melillo & Mawn 2004; Rhoten, 2004; Lynch 2006; Jacobs & Frickel 2009), there are surprisingly few empirical analyses of the reasons why individual researchers become involved in Interdisciplinary Research projects. Responding to this gap in the extant literature, the current study was undertaken to identify individual influences and motivations for participating in Interdisciplinary Research projects. In this paper we report findings that emerged from 30 interviews with researchers from a wide range of disciplines, as well as different stage of career, on the major reasons why they are drawn to Interdisciplinary Research. As part of the paper we also report the extent to which participants agreed or disagreed with a variety of pitfalls identified in the literature as potential impediments or deterrents to individuals becoming involved in Interdisciplinary studies
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