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Research into second language (L2) reading is an exponentially growing field. Yet, it still has a relatively short supply of comparable, ecologically valid data from readers representing a variety of first languages (L1). This article addresses this need by presenting a new data resource called MECO L2 (Multilingual Eye Movements Corpus), a rich behavioral eye-tracking record of text reading in English as an L2 among 543 university student speakers of 12 different L1s. MECO L2 includes a test battery of component skills of reading and allows for a comparison of the participants’ reading performance in their L1 and L2. This data resource enables innovative large-scale cross-sample analyses of predictors of L2 reading fluency and comprehension. We first introduce the design and structure of the MECO L2 resource, along with reliability estimates and basic descriptive analyses. Then, we illustrate the utility of MECO L2 by quantifying contributions of four sources to variability in L2 reading proficiency proposed in prior literature: reading fluency and comprehension in L1, proficiency in L2 component skills of reading, extralinguistic factors, and the L1 of the readers. Major findings included (a) a fundamental contrast between the determinants of L2 reading fluency versus comprehension accuracy, and (b) high within-participant consistency in the real-time strategy of reading in L1 and L2. We conclude by reviewing the implications of these findings to theories of L2 acquisition and outline further directions in which the new data resource may support L2 reading research.

ESR spectra of three spin probes with different molecular volumes: 2,2,6,6-tetramethyl-4-oxopiperidine-1-oxyl, di-p-anisylnitroxide, and nitroxide derivative of fullerene in glassy polystyrene, polyvinyl trimethylsilane, and Teflon AF-2400 were calculated numerically within the model of quasi-libration motions. Temperature ranges, where the model is capable to reproduce spectra within experimental errors, were defined. It was found that simulation of X-band ESR spectra allows to determine quasi-libration amplitudes around molecular axes X and Y with accuracy $ 3 and around Z axis with accuracy $ 15-20 . A shape of distribution of quasilibration amplitudes was also determined qualitatively by ESR spectra simulations. It was established that the average amplitude of quasi-libration motion depends on the free volume of each polymer and geometrical molecular volume of a spin probe. Quasi-libration amplitudes increase as the temperature increases, and reach the value of 40 degrees. We found that upon further temperature increase, quasi-libration model becomes inapplicable for quantitative numerical spectra simulation.

The rotational mobility of molecules in glassy polymers was investigated by quantitative simulations of electron spin resonance spectra of nitroxide spin probes with molecules of different sizes. The motional models were determined unambiguously when the experimental and calculated spectra coincided within the level of experimental error. Temperature ranges in which different motional models were applicable were determined. Quasilibrational movements and the distribution of rotational mobility were found to be necessary for the qualitative description of spin-probe mobility in glassy polymers. The quantitative and empirical characteristics of rotational mobility were examined.

Temperature dependencies of ESR spectra of nitroxide spin probes in glassy polymers near and below glass transition temperature were examined in detail. Three temperature ranges, each characterized by specific changes in spectral shape, were defined. (i) In the low temperature range, ESR spectra of nitroxide radical in glassy polymer matrix weakly depend on temperature and remain qualitatively the same. (ii) In the intermediate temperature range, significant changes in the shape of spectra are observed. (iii) A new phenomenon was revealed near and below glass transition temperature: narrowing of linewidths occurs while the ratio of amplitudes of different components varies insignificantly. Analysis of molecular rotational mobility was carried out by means of commonly used empirical approaches. It was shown that widely used formulas and empirical approaches are not applicable for characterization of molecular mobility in glassy polymers. Mechanisms of rotational molecular movements in glassy polymers are discussed. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 563–575, 2009