235 research outputs found
Spectral Modeling of SNe Ia Near Maximum Light: Probing the Characteristics of Hydro Models
We have performed detailed NLTE spectral synthesis modeling of 2 types of 1-D
hydro models: the very highly parameterized deflagration model W7, and two
delayed detonation models. We find that overall both models do about equally
well at fitting well observed SNe Ia near to maximum light. However, the Si II
6150 feature of W7 is systematically too fast, whereas for the delayed
detonation models it is also somewhat too fast, but significantly better than
that of W7. We find that a parameterized mixed model does the best job of
reproducing the Si II 6150 line near maximum light and we study the differences
in the models that lead to better fits to normal SNe Ia. We discuss what is
required of a hydro model to fit the spectra of observed SNe Ia near maximum
light.Comment: 29 pages, 14 figures, ApJ, in pres
Assumptions behind grammatical approaches to code-switching: when the blueprint is a red herring
Many of the so-called âgrammarsâ of code-switching are based on various underlying assumptions, e.g. that informal speech can be adequately or appropriately described in terms of ââgrammarââ; that deep, rather than surface, structures are involved in code-switching; that one âlanguageâ is the âbaseâ or âmatrixâ; and that constraints derived from existing data are universal and predictive. We question these assumptions on several grounds. First, âgrammarâ is arguably distinct from the processes driving speech production. Second, the role of grammar is mediated by the variable, poly-idiolectal repertoires of bilingual speakers. Third, in many instances of CS the notion of a âbaseâ system is either irrelevant, or fails to explain the facts. Fourth, sociolinguistic factors frequently override âgrammaticalâ factors, as evidence from the same language pairs in different settings has shown. No principles proposed to date account for all the facts, and it seems unlikely that âgrammarâ, as conventionally conceived, can provide definitive answers. We conclude that rather than seeking universal, predictive grammatical rules, research on CS should focus on the variability of bilingual grammars
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L1 transfer in the acquisition of manner and path in Spanish by native speakers of English
In this article the authors argue that L1 transfer from English is not only important in the early stages of L2 acquisition of Spanish, but remains influential in later stages if there is not enough positive evidence for the learners to progress in their development (Lefebvre, White, & Jourdan, 2006). The findings are based on analyses of path and manner of movement in stories told by British students of Spanish (N = 68) of three different proficiency levels. Verbs that conflate motion and path, on the one hand, are mastered early, possibly because the existence of Latinate path verbs, such as enter and ascend in English, facilitate their early acquisition by British learners of Spanish. Contrary to the findings of Cadierno (2004) and Cadierno and Ruiz (2006), the encoding of manner, in particular in boundary crossing contexts, seems to pose enormous difficulties, even among students who had been abroad on a placement in a Spanish-speaking country prior to the data collection. An analysis of the frequency of manner verbs in Spanish corpora shows that one of the key reasons why students struggle with manner is that manner verbs are so infrequent in Spanish. The authors claim that scarce positive evidence in the language exposed to and little or no negative evidence are responsible for the long-lasting effect of transfer on the expression of manner
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Operationalising and measuring language dominance
The paper offers a new way to measure language ability in bilinguals, based on measures of lexical richness. The validity of proposed approach is tested in a variety of ways
A High Intrinsic Peculiarity Rate Among Type Ia Supernovae
We have compiled a sample of 45 Type Ia supernovae (SNe Ia) discovered by the
Lick Observatory Supernova Search (LOSS) and the Beijing Astronomical
Observatory Supernova Survey (BAOSS), and determined the rate of
spectroscopically peculiar SNe Ia (i.e., SN 1986G-like, SN 1991bg-like, and SN
1991T-like objects) and the luminosity function of SNe Ia. Because of the
nature of the two surveys (distance-limited with small baselines and deep
limiting magnitudes), nearly all SNe Ia have been discovered in the sample
galaxies of LOSS and BAOSS; thus, the observed peculiarity rate and luminosity
function of SNe Ia are intrinsic. We find that 369% of nearby SNe Ia are
peculiar; specifically, the luminosity function of SNe Ia consists of 20% SN
1991T-like, 64% normal, and 16% SN 1991bg-like objects. We have compared our
results to those found by earlier studies, and to those found at high redshift.
The apparent dearth of SN 1991T-like objects at high redshift may be due to
extinction, and especially to the difficulty of recognizing them from spectra
obtained past maximum brightness or from spectra with low signal-to-noise
ratios. Implications of the high peculiarity rate for the progenitor systems of
SNe Ia are also briefly discussed.Comment: 20 pages, 7 figures, accepted for publication in the Ap
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The role of statistical learning in the acquisition of motion event construal in a second language
Learning to talk about motion in a second language is very difficult because it involves restructuring deeply entrenched patterns from the first language (Slobin 1996). In this paper we argue that statistical learning (Saffran et al. 1997) can explain why L2 learners are only partially successful in restructuring their second language grammars. We explore to what extent L2 learners make use of two mechanisms of statistical learning, entrenchment and pre-emption (Boyd and Goldberg 2011) to acquire target-like expressions of motion and retreat from overgeneralisation in this domain. Paying attention to the frequency of existing patterns in the input can help learners to adjust the frequency with which they use path and manner verbs in French but is insufficient to acquire the boundary crossing constraint (Slobin and Hoiting 1994) and learn what not to say. We also look at the role of language proficiency and exposure to French in explaining the findings
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(In)Complete acquisition of Turkish among Turkish German bilinguals in Germany and Turkey: an analysis of complex embeddings in narratives
Although most researchers recognise that the language repertoire of bilinguals can mvary, few studies have tried to address variation in bilingual competence in any
detail. This study aims to take a first step towards further understanding the way in which bilingual competencies can vary at the level of syntax by comparing the use of syntactic embeddings among three different groups of Turkish/German bilinguals.
The approach of the present paper is new in that different groups of bilinguals are compared with each other, and not only with monolingual speakers, as is common in most studies in the field. The analysis focuses on differences in the use of embeddings in Turkish, which are generally considered to be one of the more complex aspects of Turkish grammar. The study shows that young Turkish/German
bilingual adults who were born and raised in Germany use fewer, and less complex embeddings than Turkish/German bilingual returnees who had lived in Turkey for
eight years at the time of recording. The present study provides new insights in the nature of bilingual competence, as well as a new perspective on syntactic change in immigrant Turkish as spoken in Europe
UBVRI Light Curves of 44 Type Ia Supernovae
We present UBVRI photometry of 44 type-Ia supernovae (SN Ia) observed from
1997 to 2001 as part of a continuing monitoring campaign at the Fred Lawrence
Whipple Observatory of the Harvard-Smithsonian Center for Astrophysics. The
data set comprises 2190 observations and is the largest homogeneously observed
and reduced sample of SN Ia to date, nearly doubling the number of
well-observed, nearby SN Ia with published multicolor CCD light curves. The
large sample of U-band photometry is a unique addition, with important
connections to SN Ia observed at high redshift. The decline rate of SN Ia
U-band light curves correlates well with the decline rate in other bands, as
does the U-B color at maximum light. However, the U-band peak magnitudes show
an increased dispersion relative to other bands even after accounting for
extinction and decline rate, amounting to an additional ~40% intrinsic scatter
compared to B-band.Comment: 84 authors, 71 pages, 51 tables, 10 figures. Accepted for publication
in the Astronomical Journal. Version with high-res figures and electronic
data at http://astron.berkeley.edu/~saurabh/cfa2snIa
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