L2 English Article Use by L1 Speakers of Article-less Languages: A Learner Corpus Study

This paper adopts the Integrated Contrastive Model (Granger 1996) to an examination of the use of articles in the L2 English written production of L1 speakers of three article-less languages (Mandarin Chinese, Korean and Thai) across four L2 proficiency levels. Data is sourced from the International Corpus Network of Asian Learners of English (ICNALE; Ishikawa 2011, 2013), comprising 575 written essays totalling 125,588 words across two writing prompts. Accuracy of zero, indefinite and definite articles is measured using Pica’s (1983) Target Language Use across Bickerton’s (1981) semantic/pragmatic article contexts (generic, specific definite, specific indefinite and non-specific indefinite). The results show two different orders of article accuracy depending on L1 background, as well as effects of writing prompt on the accuracy of certain article forms, and evidence of pseudo-longitudinal development for particular article usages as L2 proficiency increases, although not in all cases. Massive overproduction of indefinite/definite articles in generic contexts is problematic for all three L2 groups regardless of L1 background and L2 proficiency. However, Mandarin L2 English users appear to enjoy a significant advantage in L2 article accuracy over Korean or Thai L2 English users in almost all contexts of use and L2 proficiency levels, providing further potential evidence that the often reported grammaticalisation of definiteness/specificity markers in L1 Mandarin is aiding Mandarin L2 English users’ acquisition of the English article system.postprin

Observations of Mariner IV with the Parkes 210-ft Radio Telescope

Radio telescope test results from Mariner IV OBSERVATION

A Learner Corpus investigation of Filipino L2 English article use: The way forward for language teachers

It is well-documented that L2 English learners from article-less languages, such as Mandarin and Korean, have trouble appropriately marking definiteness/specificity in L2 English, causing numerous breakdowns in referential coherence. The status of Filipino / Tagalog as an article or article-less language is up for debate, with ANG, NG, SA markers used to signal definiteness, indefiniteness and genericity according to context. This paper presents a learner corpus analysis of L2 English definite article use by L1 Tagalog speakers, collected from the International Corpus of Learner English (ICNALE, Ishikawa, 2013), totalling 24,253 words from 94 essays. Using Pica's (1983) Target Language Use as a measure of article accuracy across the production of zero, indefinite and definite articles across four types of obligatory contexts (generic, specific definite, specific indefinite and non-specific indefinite), the results show that Filipino L2 English users struggle with the use of the definite article in generic contexts, much like the findings reported for Mandarin, Korean and Thai in the author's and others’ previous research. Based on the results of this analysis, a number of suggestions for pedagogy are presented, looking at how Filipino learners use articles successfully, when they do not, and what can be done to improve Filipino L2 English learners' accuracy and range of definite article use.preprin

The Magellan/IMACS Catalog of Optical Supernova Remnant Candidates in M83

We present a new optical imaging survey of supernova remnants in M83, using data obtained with the Magellan I 6.5m telescope and IMACS instrument under conditions of excellent seeing. Using the criterion of strong [S II] emission relative to Halpha, we confirm all but three of the 71 SNR candidates listed in our previous survey, and expand the SNR candidate list to 225 objects, more than tripling the earlier sample. Comparing the optical survey with a new deep X-ray survey of M83 with Chandra, we find 61 of these SNR candidates to have X-ray counterparts. We also identify an additional list of 46 [O III] -selected nebulae for follow-up as potential ejecta-dominated remnants, seven of which have associated X-ray emission that makes them strong candidates. Some of the other [O III]-bright objects could also be normal ISM-dominated supernova remnants with shocks fast enough to doubly ionize oxygen, but with Halpha and [S II] emission faint enough to have been missed. A few of these objects may also be H II regions with abnormally high [O III] emission compared with the majority of M83 H II regions, compact nebulae excited by young Wolf-Rayet stars, or even background AGN. The supernova remnant Halpha luminosity function in M83 is shifted a factor of ~ 4.5x higher than for M33 supernova remnants, indicative of a higher mean ISM density in M83. We describe the search technique used to identify the supernova remnant candidates and provide basic information and finder charts for the objects.Comment: 40 pages, 15 figures, accepted for ApJ

Molecular Gas in Spiral Galaxies

In this review, I highlight a number of recent surveys of molecular gas in nearby spiral galaxies. Through such surveys, more complete observations of the distribution and kinematics of molecular gas have become available for galaxies with a wider range of properties (e.g., brightness, Hubble type, strength of spiral or bar structure). These studies show the promise of both interferometers and single-dish telescopes in advancing our general understanding of molecular gas in spiral galaxies. In particular, I highlight the contributions of the recent BIMA Survey of Nearby Galaxies (SONG).Comment: 8 pages, 1 figure. To appear in the proceedings of the 4th Cologne-Bonn-Zermatt-Symposium, "The Dense Interstellar Medium in Galaxies", which was held in Zermatt, Switzerland in September 200

[S IV] in the NGC 5253 Supernebula: Ionized Gas Kinematics at High Resolution

The nearby dwarf starburst galaxy NGC 5253 hosts a deeply embedded radio-infrared supernebula excited by thousands of O stars. We have observed this source in the 10.5{\mu}m line of S+3 at 3.8 kms-1 spectral and 1.4" spatial resolution, using the high resolution spectrometer TEXES on the IRTF. The line profile cannot be fit well by a single Gaussian. The best simple fit describes the gas with two Gaussians, one near the galactic velocity with FWHM 33.6 km s-1 and another of similiar strength and FWHM 94 km s-1 centered \sim20 km s-1 to the blue. This suggests a model for the supernebula in which gas flows towards us out of the molecular cloud, as in a "blister" or "champagne flow" or in the HII regions modelled by Zhu (2006).Comment: Accepted for publication in the Astrophysical Journal 4 June 201

CO(1-0), CO(2-1) and Neutral Gas in NGC 6946: Molecular Gas in a Late-Type, Gas Rich, Spiral Galaxy

We present "On The Fly" maps of the CO(1-0) and CO(2-1) emission covering a 10' X 10' region of the NGC 6946. Using our CO maps and archival VLA HI observations we create a total gas surface density map, Sigma_gas, for NGC 6946. The predominantly molecular inner gas disk transitions smoothly into an atomic outer gas disk, with equivalent atomic and molecular gas surface densities at R = 3.5' (6 kpc). We estimate that the total H2 mass is 3 X 10^9 Mo, roughly 1/3 of the interstellar hydrogen gas mass, and about 2% of the dynamical mass of the galaxy at our assumed distance of 6 Mpc. The value of the CO(2-1)/CO(1-0) line ratio ranges from 0.35 to 2; 50% of the map is covered by very high ratio, >1, gas. The very high ratios are predominantly from interarm regions and appear to indicate the presence of wide-spread optically thin gas. Star formation tracers are better correlated with the total neutral gas disk than with the molecular gas by itself implying SFR is proportional to Sigma_gas. Using the 100 FIR and 21 cm continuum from NGC 6946 as star formation tracers, we arrive at a gas consumption timescale of 2.8 Gyr, which is relatively uniform across the disk. The high star formation rate at the nucleus appears to be due to a large accumulation of molecular gas rather than a large increase in the star formation efficiency. The mid-plane gas pressure in the outer (R > 10 kpc) HI arms of NGC 6946 is close to the value at the radial limit (10 kpc) of our observed CO disk. If the mid-plane gas pressure is a factor for the formation of molecular clouds, these outer HI gas arms should contain molecular gas which we do not see because they are beyond our detection limit

The volume densities of giant molecular clouds in M83

Using observed GALEX far-ultraviolet (FUV) fluxes and VLA images of the 21-cm HI column densities, along with estimates of the local dust abundances, we measure the volume densities of a sample of actively star-forming giant molecular clouds (GMCs) in the nearby spiral galaxy M83 on a typical resolution scale of 170 pc. Our approach is based on an equilibrium model for the cycle of molecular hydrogen formation on dust grains and photodissociation under the influence of the FUV radiation on the cloud surfaces of GMCs. We find a range of total volume densities on the surface of GMCs in M83, namely 0.1 - 400 cm-3 inside R25, 0.5 - 50 cm-3 outside R25 . Our data include a number of GMCs in the HI ring surrounding this galaxy. Finally, we discuss the effects of observational selection, which may bias our results.Comment: 9 pages, 11 figure

Ram pressure drag - the effects of ram pressure on dark matter and stellar disk dynamics

We investigate the effects of ram pressure stripping on gas-rich disk galaxies in the cluster environment. Ram pressure stripping principally effects the atomic gas in disk galaxies, stripping away outer disk gas to a truncation radius. We demonstrate that the drag force exerted on truncated gas disks is passed to the stellar disk, and surrounding dark matter through their mutual gravity. Using a toy model of ram pressure stripping, we show that this can drag a stellar disk and dark matter cusp off centre within it's dark matter halo by several kiloparsecs. We present a simple analytical description of this process that predicts the drag force strength and its dependency on ram pressures and disk galaxy properties to first order. The motion of the disk can result in temporary deformation of the stellar disk. However we demonstrate that the key source of stellar disk heating is the removal of the gas potential from within the disk. This can result in disk thickening by approximately a factor of two in gas-rich disks.Comment: Accepted by MNRAS (Oct 2011) 17 pages, 11 figures, 1 tabl