A versatile microprocessor-based data acquisition system for a bioengineering instrumentation laboratory

Call number: LD2668 .T4 1979 K56Master of Scienc

A CNO Dichotomy among O2 Giant Spectra in the Magellanic Clouds

From a survey of the 3400 Å region in the earliest O-type spectra, we have found that two of the four O2 giants observed in the Large Magellanic Cloud have O IV lines there that are stronger than the N IV lines, while the other two have the opposite. A Small Magellanic Cloud counterpart also has N IV stronger than O IV. Inspection of the blue spectra of these stars shows that the former pair have weaker N lines in all ionization states (III, IV, and V) present as well as lines of C IV λ4658, while the latter three have stronger N lines and greater He/H. Space ultraviolet observations of two of the N-strong stars show N V wind profiles substantially stronger than those of C IV, while in the N-weak stars the C IV features are equal to or stronger than the N V. The N-strong stars are now reclassified as ON2 III(f*), newly defining that category. These characteristics strongly suggest a larger fraction of processed material in the atmospheres of the ON2 stars, which we confirm by modeling the optical spectra. In the context of current models, it is in turn implied that the ON2 stars are in a more advanced evolutionary state than the others, and/or that they had higher initial rotational velocities. The recent formulation of the effects of rotation on massive stellar evolution introduces an additional fundamental parameter, which the CNO abundances are in principle able to constrain. We present some illustrative comparisons with current Geneva evolutionary models for rotating massive stars. It is possible that these very hot, nitrogen-rich objects are products of homogeneous evolution. Our results will provide motivation for further physical modeling of the atmospheres and evolutionary histories of the most massive hot stars.Fil: Walborn, Nolan Revere. Space Telescope Science Institute; Estados UnidosFil: Morrell, Nidia Irene. Las campanas observatory; ChileFil: Howarth, Ian D.. University College London; Estados UnidosFil: Crowther, Paul A.. University of Sheffield; Reino UnidoFil: Lennon, Daniel J.. Isaac Newton Group of Telescopes; EspañaFil: Massey, Philip. Lowell Observatory; Estados UnidosFil: Arias, Julia Ines. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentin

Sentiment Analysis: Comparative Analysis of Multilingual Sentiment and Opinion Classification Techniques

Sentiment analysis and opinion mining have become emerging topics of research in recent years but most of the work is focused on data in the English language. A comprehensive research and analysis are essential which considers multiple languages, machine translation techniques, and different classifiers. This paper presents, a comparative analysis of different approaches for multilingual sentiment analysis. These approaches are divided into two parts: one using classification of text without language translation and second using the translation of testing data to a target language, such as English, before classification. The presented research and results are useful for understanding whether machine translation should be used for multilingual sentiment analysis or building language specific sentiment classification systems is a better approach. The effects of language translation techniques, features, and accuracy of various classifiers for multilingual sentiment analysis is also discussed in this study

Clustering around radio galaxies at z~1.5

The importance of studying old elliptical galaxies at redshift z ~ 1.5 is reviewed, considering both what can be learned by extending studies of the evolution of cluster galaxy scaling relations to earlier cosmic epochs, and the age-dating of old elliptical galaxies at high redshifts. Following this, the first results are provided of an on-going project to find such distant elliptical galaxies, through an investigation of the cluster environments of powerful radio sources with redshifts 1.44 < z < 1.7. These studies show a considerable excess of red galaxies in the radio sources fields, with the magnitudes (K >~ 17.5) and colours (R-K > 4) expected of old passively evolving galaxies at the radio source redshift. The red galaxy overdensities are found on two different scales around the radio sources; a pronounced small-scale peak at radial distances of <~ 150 kpc, and a weaker large-scale excess extending out to 1 - 1.5 Mpc. The presence and richness of these red galaxy excesses varies considerably from source to source. An interpretation of these results is provided.Comment: LaTeX, 6 pages, Elsevier Science format. To appear in "Radio galaxies: past, present & future". eds. M. Jarvis et al., Leiden, Nov 200

A High Angular Resolution Survey of Massive Stars in Cygnus OB2: Results from the Hubble Space Telescope Fine Guidance Sensors

We present results of a high angular resolution survey of massive OB stars in the Cygnus OB2 association that we conducted with the Fine Guidance Sensor 1R (FGS1r) on the Hubble Space Telescope. FGS1r is able to resolve binary systems with a magnitude difference delta-V < 4 down to separations as small as 0.01 arcsec. The sample includes 58 of the brighter members of Cyg OB2, one of the closest examples of an environment containing a large number of very young and massive stars. We resolved binary companions for 12 targets and confirmed the triple nature of one other target, and we offer evidence of marginally resolved companions for two additional stars. We confirm the binary nature of 11 of these systems from complementary adaptive optics imaging observations. The overall binary frequency in our study is 22% to 26% corresponding to orbital periods ranging from 20 - 20,000 years. When combined with the known short-period spectroscopic binaries, the results supports the hypothesis that the binary fraction among massive stars is > 60%. One of the new discoveries is a companion to the hypergiant star MT 304 = Cyg OB2-12, and future measurements of orbital motion should provide mass estimates for this very luminous star.Comment: accepted for AJ, 84 pages, 61 figure

Changes in PTSD, depression, and generalized anxiety before and during the COVID-19 pandemic in Ireland

Background: : In this study, we compared the prevalence of posttraumatic stress disorder (PTSD), depression, and generalized anxiety disorder (GAD) before and during the COVID-19 pandemic across nationally representative samples of Irish adults. Methods: : Participants were sampled in February 2019 (N = 1,020), April 2020 (N = 1,041), May 2020 (N = 1,032), and December 2020 (N = 1,100) using the same self-report measures. Results: : The prevalence of PTSD significantly increased from 12.5% in 2019 to 18.0% in April 2020, to 22.0% in May, and returning to 17.6% in December 2020. PTSD increases were most consistently observed in males, those aged 18–34 years, those without a university qualification, and those living in the Leinster region of Ireland, where the capital city of Dublin is located. There were no significant changes in the prevalence of depression or GAD. Limitations: : The 2020 samples were not completely independent of one another and while the analysis took this into account, this bias cannot be completely removed. Conclusions: : These findings show an increase in PTSD during the initial stages of the COVID-19 pandemic compared to the pre-pandemic period and suggest specificity in mental health responses to the COVID-19 pandemic