Bifurcations and the Emergence of L2 Syntactic Structures in a Complex Dynamic System

We report on a complex dynamic systems study of an untutored adult French learner\u27s development of English syntax, specifically two non-finite adverbial constructions. The study was conducted over one academic year of 30 weeks. From an analysis of L2 speech samples collected weekly, certain patterns in the flux emerged. The learner\u27s ensuing second language development is characterized by a series of bifurcations, stemming from forms competing for the same functional terrain. Each bifurcation is accompanied by turbulence as the system moves from one attractor state to another. The transition is characterized by loss of stability, an increase in variability, and a period of dysfluency. It is in the dynamic relationship of accuracy and fluency that novel syntactic forms emerge, both convergent with and divergent from dominant contextual patterns, with dominance established by consulting a well-known corpus of contemporary English. Non-linear development occurs with continuous and iterative exposure to and interaction in English-from relexification to adaptation and synchronization, animated by the learner\u27s perception and memory of regular sequential associations, to pruning of divergent forms. What results over time is a branching hierarchy, connecting online processing with over time development. Multiple competing forms continue to co-exist in the learner\u27s repertoire, which is likely more typical of adult L2 development than of L1 acquisition

Complex systems and applied linguistics

This book introduces and develops the potential of complex systems as a metaphor or supra-theory for systems in applied linguistics. Change and heterogeneity are central to complex systems theory and to the resonances that we find between complex systems and applied linguistics systems. The book explores these resonances and what happens when complex systems theory is used to make sense of central areas of applied linguistic concerns: language, language learning, discourse and the language classroom. Principles of complex systems theory are explained, drawing on work that has been most developed in the biological sciences and that is being extended into the social sciences, developmental psychology and other applied disciplines. These principles importantly include descriptions of change over time (system dynamics) that work for all levels and scales: movement from temporary and relative stability through adaptive behaviours and self-organisation to the emergence of new patterns that are not amenable to reductive explanations. Seeing applied systems as complex, adaptive and dynamic opens up new conceptualisations of properties and activities, enables new questions about how people use, learn and teach languages, and demands new ways of investigating behaviour and development

The Globular Cluster System of NGC 5128 II. Ages, Metallicities, Kinematics, and Formation

We present a study of the nearby post-merger giant elliptical galaxy, NGC 5128 (Centaurus A), in which we use the properties of its globular cluster (GC) and planetary nebula (PN) systems to constrain its evolution. Using photometric and spectroscopic data for 215 GCs presented in Paper I, we study trends in age, metallicity, and kinematics for the GC system. We confirm that the GC metallicity distribution is bimodal, and show that these two sub-populations have different properties. Using spectral line index measurements of the brightest clusters, the metal-poor GCs have old ages like the Milky Way globular clusters, while the metal-rich GCs have H-beta line-strengths that could be interpreted as a mean age of ~5 (+3/-2) Gyr. Both populations appear to have [Mg/Fe] ratios consistent with that of the Galactic GC system, although this quantity is not very well-constrained. The kinematics of the metal-rich GCs are similar to those of the planetary nebulae, exhibiting significant rotation about a misaligned axis, while the metal-poor GCs have a higher velocity dispersion and show a weaker kinematic correlation with the field stars. The total gravitating mass of NGC 5128 derived from the GCs is in excellent agreement with the value derived from stellar (PN) kinematics. We suggest that these and other data support a picture in which the main body of NGC 5128 was formed 3-8 Gyr ago by the dissipational merger of two unequal-mass disk galaxies supplemented by the continual accretion of both gas-rich and gas-poor satellites.Comment: 15 pages, 21 figures (figures 14-20 best viewed in color), accepted for publication in the Astrophysical Journa

Mapping the Galactic Halo I. The `Spaghetti' Survey

We describe a major survey of the Milky Way halo designed to test for kinematic substructure caused by destruction of accreted satellites. We use the Washington photometric system to identify halo stars efficiently for spectroscopic followup. Tracers include halo giants (detectable out to more than 100 kpc), blue horizontal branch stars, halo stars near the main sequence turnoff, and the ``blue metal-poor stars'' of Preston et al (1994). We demonstrate the success of our survey by showing spectra of stars we have identified in all these categories, including giants as distant as 75 kpc. We discuss the problem of identifying the most distant halo giants. In particular, extremely metal-poor halo K dwarfs are present in approximately equal numbers to the distant giants for V fainter than 18, and we show that our method will distinguish reliably between these two groups of metal-poor stars. We plan to survey 100 square degrees at high galactic latitude, and expect to increase the numbers of known halo giants, BHB stars and turnoff stars by more than an order of magnitude. In addition to the strong test that this large sample will provide for the question `was the Milky Way halo accreted from satellite galaxies?', we will improve the accuracy of mass measurements of the Milky Way beyond 50 kpc via the kinematics of the many distant giants and BHB stars we will find. We show that one of our first datasets constrains the halo density law over galactocentric radii of 5-20 kpc and z heights of 2-15 kpc. The data support a flattened power-law halo with b/a of 0.6 and exponent -3.0. More complex models with a varying axial ratio may be needed with a larger dataset.Comment: 55 pages, 22 figures, to appear in the Astronomical Journa

The Chandra Local Volume Survey: The X-ray Point Source Catalog of NGC 300

We present the source catalog of a new Chandra ACIS-I observation of NGC 300 obtained as part of the Chandra Local Volume Survey. Our 63 ks exposure covers ~88% of the D25 isophote (R~6.3 kpc) and yields a catalog of 95 X-ray point sources detected at high significance to a limiting unabsorbed 0.35-8 keV luminosity of ~10^36 erg s^-1. Sources were cross-correlated with a previous XMM-Newton catalog, and we find 75 "X-ray transient candidate" sources that were detected by one observatory, but not the other. We derive an X-ray scale length of 1.7+/-0.2 kpc and a recent star formation rate of 0.12 Msun yr^-1, in excellent agreement with optical observations. Deep, multi-color imaging from the Hubble Space Telescope, covering ~32% of our Chandra field, was used to search for optical counterparts to the X-ray sources, and we have developed a new source classification scheme to determine which sources are likely X-ray binaries, supernova remnants, and background AGN candidates. Finally, we present the X-ray luminosity functions (XLFs) at different X-ray energies, and we find the total NGC 300 X-ray point source population to be consistent with other late-type galaxies hosting young stellar populations (<50 Myr). We find XLF of sources associated with older stellar populations has a steeper slope than the XLF of X-ray sources coinciding with young stellar populations, consistent with theoretical predictions.Comment: 23 pages, 13 figures. Accepted to Ap

Special topic: The association between pulse ingredients and canine dilated cardiomyopathy: addressing the knowledge gaps before establishing causation.

In July 2018, the Food and Drug Administration warned about a possible relationship between dilated cardiomyopathy (DCM) in dogs and the consumption of dog food formulated with potatoes and pulse ingredients. This issue may impede utilization of pulse ingredients in dog food or consideration of alternative proteins. Pulse ingredients have been used in the pet food industry for over 2 decades and represent a valuable source of protein to compliment animal-based ingredients. Moreover, individual ingredients used in commercial foods do not represent the final nutrient concentration of the complete diet. Thus, nutritionists formulating dog food must balance complementary ingredients to fulfill the animal's nutrient needs in the final diet. There are multiple factors that should be considered, including differences in nutrient digestibility and overall bioavailability, the fermentability and quantity of fiber, and interactions among food constituents that can increase the risk of DCM development. Taurine is a dispensable amino acid that has been linked to DCM in dogs. As such, adequate supply of taurine and/or precursors for taurine synthesis plays an important role in preventing DCM. However, requirements of amino acids in dogs are not well investigated and are presented in total dietary content basis which does not account for bioavailability or digestibility. Similarly, any nutrient (e.g., soluble and fermentable fiber) or physiological condition (e.g., size of the dog, sex, and age) that increases the requirement for taurine will also augment the possibility for DCM development. Dog food formulators should have a deep knowledge of processing methodologies and nutrient interactions beyond meeting the Association of American Feed Control Officials nutrient profiles and should not carelessly follow unsubstantiated market trends. Vegetable ingredients, including pulses, are nutritious and can be used in combination with complementary ingredients to meet the nutritional needs of the dog

Understanding the nature of variations in postgraduate learners’ willingness to communicate in English

Willingness to communicate in a second language (L2 WTC) is a learner’s volitional participation in oral communication using L2. Previous research has expended considerable attention to the stable, trait-like disposition of learners’ L2 WTC, while less focus has been accorded to the complex nature of variations in L2 WTC on multiple timescales. Using dynamic systems theory, the present article examines the complex nature of variations on three timescales: during conversation, between classes and over time. The data were obtained from six postgraduate students through structured classroom observations, learners’ diaries, stimulated recalls and biographic questionnaires. The findings show that while variations in L2 WTC within and between the classes were influenced by situational variables, such as interlocutors, topic and perceived opportunity, variations over 14 classes were strongly affected by enduring factors, such as personality and trait-level motivation. Introverted learners showed dependency on their interlocutors to provide them with opportunities for L2 use. Conversely, extraverted learners proactively exploited opportunities to use L2 regardless of the nature of topic of discussion and the behaviour of interlocutors. The study also discusses a number of implications for language teaching and teacher education

Teaching and assessing EIL in local contexts around the world

The book addresses currently contested issues in English Language Teaching (ELT), especially with regard to the need to revisit and contextualize the existing monolithic concepts of English and native speaker to a broader and more accommodative view of pluralistic concept of World Englishes. McKay and Brown advocate the recognition that ELT learners are equally legitimate users of Englishes, and argue for the contextual grounding of ELT teaching and learning based on students’ need. It is a particularly relevant book for teachers of English and students from outer and expanding circles to provide them with greater understanding of their learning goals and how to achieve them. Divided into seven chapters, the first three chapters deal with an overview of the social and educational context of English as an International Language (EIL) classrooms and then it moves on to the discussion of the stereotype of

Fashionably Late? Building up the Milky Way's Inner Halo

Using a sample of 248 metal-poor stars (RR Lyraes, red giants and RHB stars) which is remarkable for the accuracy of its 6-D kinematical data, we find a new component for the local halo which has an axial ratio c/a ~ 0.2, a similar flattening to the thick disk. It has a small prograde rotation but is supported by velocity anisotropy, and contains more intermediate-metallicity stars (with -1.5 < [Fe/H] < -1.0) than the rest of our sample. We suggest that this component was formed quite late, during or after the formation of the disk. It formed either from the gas that was accreted by the last major mergers experienced by the Galaxy, or by dynamical friction of massive infalling satellite(s) with the halo and possibly the stellar disk or thick disk. The remainder of the stars in our sample exhibit a clumpy distribution in energy and angular momentum, suggesting that the early, chaotic conditions under which the inner halo formed were not violent enough to erase the record of their origins. The clumpy structure suggests that a relatively small number of progenitors were responsible for building up the inner halo, in line with theoretical expectations. We find a difference in mean binding energy between the RR Lyrae variables and the red giants in our sample, suggesting that more of the RR Lyraes in the sample belong to the outer halo, and that the outer halo may be somewhat younger, as first suggested by Searle and Zinn (1978). We also find that the RR Lyrae mean rotation is more negative than the red giants, which is consistent with the recent result of Carollo et al.(2007) that the outer halo has a retrograde rotation and with the difference in kinematics seen between RR Lyraes and BHB stars by Kinman et al.(2007).Comment: 16 pages, 10 figures, this version accepted by Ap