Spitzer-IRS Spectroscopy of the Prototypical Starburst Galaxy NGC7714

We present observations of the starburst galaxy NGC 7714 with the Infrared Spectrograph IRS on board the Spitzer Space Telescope. The spectra yield a wealth of ionic and molecular features that allow a detailed characterization of its properties. NGC 7714 has an HII region-like spectrum with strong PAH emission features. We find no evidence for an obscured active galactic nucleus, and with [NeIII]/[NeII]~0.73, NGC7714 lies near the upper end of normal-metallicity starburst galaxies. With very little slicate absorption and a temperature of the hottest dust component of 340K, NGC 7714 is the perfect template for a young, unobscured starburstComment: To appear in the special ApJSS issue on early results from Spitze

Tense and aspect in word problems about motion: diagram, gesture, and the felt experience of time

© 2014, Mathematics Education Research Group of Australasia, Inc. Word problems about motion contain various conjugated verb forms. As students and teachers grapple with such word problems, they jointly operationalize diagrams, gestures, and language. Drawing on findings from a 3-year research project examining the social semiotics of classroom interaction, we show how teachers and students use gesture and diagram to make sense of complex verb forms in such word problems. We focus on the grammatical category of “aspect” for how it broadens the concept of verb tense. Aspect conveys duration and completion or frequency of an event. The aspect of a verb defines its temporal flow (or lack thereof) and the location of a vantage point for making sense of this durational process

ISO observations of Hickson Compact Group 31 with the central Wolf-Rayet galaxy NGC 1741

Hickson Compact Group (HCG) 31, consisting of the Wolf-Rayet galaxy NGC 1741 and its irregular dwarf companions, was observed using the Infrared Space Observatory. The deconvolved ISOCAM maps of the galaxies using the 7.7 micron and 14.3 micron (LW6 and LW3) filters are presented, along with ISOPHOT spectrometry of the central starburst region of NGC 1741 and the nucleus of galaxy HCG 31A. Strong mid-IR emission was detected from the central burst in NGC 1741, along with strong PAH features and a blend of features including [S IV] at 10.5 micron. The 14.3/6.75 micron flux ratio, where the 6.75 micron flux was synthesized from the PHT-S spectrum, and 14.3/7.7 micron flux ratios suggest that the central burst within NGC 1741 may be moving towards the post-starburst phase. Diagnostic tools including the ratio of the integrated PAH luminosity to the 40 to 120 micron infrared luminosity and the far-infrared colours reveal that despite the high surface brightness of the nucleus, the properties of NGC 1741 can be explained in terms of a starburst and do not require the presence of an AGN. The Tycho catalogue star TYC 04758-466-1, with m$_{V}$ = 11.3 and spectral type F6, was detected at 7.7 and 14.3 microns.Comment: 27 pages, 7 figures. Accepted for publication in the Astrophysical Journa

The Link Between Star Formation and Accretion in LINERs: A Comparison with other AGN Subclasses

We present archival high resolution X-ray imaging observations of 25 nearby LINERs observed by ACIS on board Chandra. This sample builds on our previously published proprietary and archival X-ray observations, and includes the complete set of LINERs with published black hole masses and FIR luminosities that have been observed by Chandra. Of the 82 LINERs observed by Chandra, 41 (50%) display hard nuclear cores consistent with an AGN. The nuclear 2-10 keV luminosities of these AGN-LINERs range from ~ 2 X 10^38 ergs s^-1 to ~ 1 X 10^44 ergs s^-1. Reinforcing our previous work, we find a significant correlation between the Eddington ratio, L bol/LEdd, and the far-IR (FIR) luminosity, LFIR, as well as the IR brightness ratio, LFIR/LB in the host galaxy of AGN-LINERs that extends over seven orders of magnitude in Lbol/LEdd. Combining our AGN-LINER sample with galaxies from other AGN subclasses, we find that this correlation is reinforced in the full sample of 129 AGN, extending over almost nine orders of magnitude in Lbol/LEdd. Using archival and previously published observations of the 6.2 mm PAH feature from the Infrared Space Observatory (ISO), we find that it is unlikely that dust heating by the AGN dominates the FIR luminosity in our sample of AGN. Our results may therefore imply a fundamental link between the mass accretion rate (Mdot), as measured by the Eddington ratio, and the star formation rate (SFR), as measured by the FIR luminosity.Comment: 22 pages, 11 figures. Paper excepted for publication by ApJ in Novembe

Compassion Stress and the Qualitative Researcher

Human subjects are carefully protected in the research process. However, the same consideration is not currently being given to the qualitative researcher, even those investigating topics that are likely to elicit powerful emotions. The role of researcher’s emotional responses and the self-care strategies that, in some circumstances, are appropriate for the researcher and other research support personnel have not received the attention they deserve in qualitative research literature. Based on experience in conducting research on the topic of self-directed learning and breast cancer, and on the limited literature available, the author makes the case for the use of strategies such as counseling, peer debriefing, and journal writing as means of dealing with the potential for “compassion stress” as experienced by the researcher and other research support personnel. She also suggests that the preparation of social science researchers should include information on appropriate self-care strategies.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

Multiwavelength Study of the Starburst Galaxy NGC 7714. II: The Balance between Young, Intermediate Age and Old Stars

We combine existing multiwavelength data (incl. an HST/GHRS UV spectrum, an optical spectrum, far-IR, Xray and radio fluxes) with new HST/WFPC2 images, near-IR photometry and K band spectroscopy. We use these data to constrain the young, the intermediate age and the old stellar populations in the central 330 pc of the starburst galaxy NGC 7714. [...] We find that the young burst responsible for the UV light is only a small part of an extended episode of enhanced star formation (SF) [...]. The mass of young and intermediate age stars thus formed equals at least 10% of the mass locked in pre-existing stars of the underlying galaxy nucleus [...]. The spectrophotometric SF timescale is long compared to the ~110 Myr elapsed since closest contact with NGC 7715. The trigger of the starburst remains elusive. NGC 7714 owes its brightness in the UV to a few low extinction lines of sight towards young stars. [...] The different extinction estimates obtained from different indicators result naturally from the coexistence of populations with various ages and obscurations. The near-IR continuum image looks smoothest, as a consequence of lower sensitivity to extinction and of a larger contribution of old stars. We compare the nuclear properties of NGC 7714 with results from studies in larger apertures. We emphasize that the global properties of starburst galaxies are the result of the averaging over many lines of sight with diverse properties in terms of obscuration and stellar ages.Comment: 29 pages (+20 figures and tables), Latex2e (figs. included), uses aastex.cls. To be published in ApJ (May 2001 issue

Ferritins: furnishing proteins with iron

Ferritins are a superfamily of iron oxidation, storage and mineralization proteins found throughout the animal, plant, and microbial kingdoms. The majority of ferritins consist of 24 subunits that individually fold into 4-α-helix bundles and assemble in a highly symmetric manner to form an approximately spherical protein coat around a central cavity into which an iron-containing mineral can be formed. Channels through the coat at inter-subunit contact points facilitate passage of iron ions to and from the central cavity, and intrasubunit catalytic sites, called ferroxidase centers, drive Fe2+ oxidation and O2 reduction. Though the different members of the superfamily share a common structure, there is often little amino acid sequence identity between them. Even where there is a high degree of sequence identity between two ferritins there can be major differences in how the proteins handle iron. In this review we describe some of the important structural features of ferritins and their mineralized iron cores and examine in detail how three selected ferritins oxidise Fe2+ in order to explore the mechanistic variations that exist amongst ferritins. We suggest that the mechanistic differences reflect differing evolutionary pressures on amino acid sequences, and that these differing pressures are a consequence of different primary functions for different ferritins

Doing descriptive phenomenological data collection in sport psychology research

Researchers in the field of sport psychology have begun to highlight the potential of phenomenological ap-proaches in recognising subjective experience and the essential structure of experience. Despite this, phenom-enology has been used inconsistently in the sport psychology literature thus far. Therefore, the aim of this paper is to provide theoretically informed practical guidelines for researchers who wish to employ the descrip-tive phenomenological interview in their studies. The recommended guidelines will be supported by under-pinning theory and brief personal accounts. An argument will also be presented for the potential that descrip-tive phenomenology holds in creating new knowledge through rich description. In doing so, it is hoped that this method will be utilised appropriately in future sport psychology research to not only strengthen and diver-sify the existing literature, but also the knowledge of practitioners working within the applied world of profes-sional sport

Meaning between, in, and around words, gestures and postures: multimodal meaning making in children's classroom communication

The view of language from a social semiotic perspective is clear. Language is one of many semiotic resources we employ in our communicative practices. That is to say that while language is at times dominant, it always operates within a multimodal frame and furthermore, at times modes other than language are dominant. The proposed 2014 National Curriculum for the UK, on the other hand, values pupils' face-to-face classroom interaction in terms of standard spoken English (i.e. in terms of the mode of language alone). This paper offers examples demonstrating how embodied modes such as gesture, posture, facial expression, gaze and haptics work in conjunction with speech in children's collaborative construction of knowledge. In other words, what may have been previously conceived as gaps and silences - often interpreted as an absence of language - are in fact instantiations of the work of semiotic modes other than language. In order to consider this closely, this paper offers evidence from a multimodal micro-analysis of pupil-to-pupil, face-to-face interaction in one science lesson in a Year Five UK Primary classroom. It demonstrates how children's meaning-making is achieved through apt use of all available semiotic resources