1,721,653 research outputs found
Matthews, James : Voices. A Life of Frank O'Connor
No full textRafroidi Patrick. Matthews, James : Voices. A Life of Frank O'Connor. In: Études irlandaises, n°9, 1984. pp. 349-350
Final Report of Observations and Recommendations Concerning the College of Medicine, Seoul National University, Seoul, Korea
No full textMatthews, James H.. (1958). Final Report of Observations and Recommendations Concerning the College of Medicine, Seoul National University, Seoul, Korea. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/119125
Disc winds matter: modelling accretion and outflow on all scales
No full textOutflows are ubiquitous in accreting systems across 10 orders of magnitude in mass, and there is good evidence that mass-loaded winds are launched from the accretion discs of quasars and cataclysmic variables (CVs). Perhaps the most spectacular evidence for accretion disc winds is the blue-shifted, broad absorption lines (BALs) in UV resonance lines, seen in CVs and the BAL quasars. As well as imprinting absorption features, disc winds may affect the line and continuum emission from accreting objects. They thus offer a natural way to unify much of the phenomenology of CVs and active galactic nuclei (AGN).In this thesis, I use a state-of-the-art Monte Carlo radiative transfer (MCRT) code, Python, to conduct a series of simulations designed to test simple biconical disc wind models. I outline the MCRT techniques used, before describing a series of code validation exercises. Having tested my methods thoroughly, I explore whether the winds that are responsible for the UV BALs in high-state CVs could also have an effect on the optical spectrum. I find that the wind produces strong emission in the Balmer series, He ii 4686 A and a series of He i lines. The model shows the observed trends with inclination and in some cases produces sufficient recombination continuum emission to fill in the Balmer photoabsorption edge intrinsic to disc atmospheres. The results suggest that disc winds could have a significant impact on the optical spectra of high-state CVs.The next step was to apply the techniques to quasar winds in a test of disc wind unification models. In previous efforts, the ouflow tended to become 'over-ionized', and BAL features were only present if the X-ray luminosity was limited to around 1043 erg s-1. The outflow also failed to produce significant line emission. Motivated by these problems, I introduce a simple treatment of clumping and find that it allows BAL features to form in the rest-frame UV at more realistic X-ray luminosities. The fiducial model shows good agreement with AGN X-ray properties and the wind produces strong line emission. Despite these successes, the model cannot reproduce all emission lines seen in quasar spectra with the correct equivalent width (EW) ratios, and I find the emission line EWs have a strong dependence on inclination.Informed by the quasar wind modelling, I examine the emission line EW distributions of quasars in the context of geometric unification. I find that the observed distributions are not consistent with a model in which an equatorial BAL outflow rises from a foreshortened accretion disc. I discuss this finding in the context of other observational orientation indicators. Finally, I summarise my findings and suggest avenues for future work. Overall, the work presented here suggests that disc winds matter. They not only act as a spectral 'filter' for the underlying accretion continuum, but may actually dominate the emergent spectrum from accreting objects. As a result, unveiling their driving mechanisms, mass-loss rates and ionization structure is an important goal for the astronomical community
Re-creation of aerosol charge state found near HV power lines using a high voltage corona charger
No full textCorona ionisation from AC HV power lines (HVPL) can release ions into the environment, which have the potential to electrically charge pollutant aerosol in the atmosphere. It has been hypothesised that these charged particles have an enhanced probability of being deposited in human airways upon inhalation due to electrostatic attraction by image charge within the lung, with implications for human health. Carbonaceous aerosol particles from a Technegas generator were artificially charge-enhanced using a corona charger. Once generated, particles were passed through the charger, which was either on or off, and stored in a 15 litre conducting bag for ~20 minutes to observe size and charge distribution changes over time. Charge states were estimated using two Sequential Mobility Particle Sizers measuring the size and mobility distributions. Charge-neutral particles were measured 7 times and positive particles 9 times, the average charge-neutral value of x was 1.00 (sd = 0.06) while the average positive value was 4.60 (0.72). The system will be used to generate positive or charge neutral particles for delivery to human volunteers in an inhalation study to assess the impact of charge on ultrafine (size < 100 nm) particle deposition
Spectral response of atmospheric electric field measurements near AC high voltage power lines
Full text linkTo understand the influence of corona ion emission on the atmospheric electrical field, measurements were made near to two AC high voltage power lines. A JCI 131 field-mill recorded the atmospheric electric field over one year. Meteorological measurements were also taken. The data series is divided in four zones (dependent on wind direction): whole zones, Z0; zone 1, Z1; zone 2, Z2; zone 3, Z3. Z3 is the least affected by corona ion emission and for that reason it is used as a reference against Z1 and Z2, which are strongly influenced by this phenomena. Analysis was undertaken for all weather days and dry days only. The Lomb-Scargle strategy developed for unevenly spaced time-series is used to calculate the spectral response of the aforementioned zones. Only frequencies above 1 minute are considered
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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