Introduction (to Special Issue on Tibetan Natural Language Processing)

This introduction surveys research on Tibetan NLP, both in China and in the West, as well as contextualizing the articles contained in the special issue

SN 2011fu: a type IIb supernova with a luminous double-peaked light curve

We present optical and near-infrared observations of the type IIb supernova (SN) 2011fu from a few days to ∼300 d after explosion. The SN presents a double-peaked light curve (LC) similar to that of SN 1993J, although more luminous and with a longer cooling phase after the primary peak. The spectral evolution is also similar to SN 1993J’s, with hydrogen dominating the spectra to ∼40 d, then helium gaining strength, and nebular emission lines appearing from ∼60 d post-explosion. The velocities derived from the P-Cygni absorptions are overall similar to those of other type IIb SNe. We have found a strong similarity between the oxygen and magnesium line profiles at late times, which suggests that these lines are forming at the same location within the ejecta. The hydrodynamical modelling of the pseudo-bolometric LC and the observed photospheric velocities suggest that SN 2011fu was the explosion of an extended star (R ∼ 450 R☉), in which 1.3 × 1051 erg of kinetic energy were released and 0.15 M of 56Ni were synthesized. In addition, a better reproduction of the observed early pseudo-bolometric LC is achieved if a more massive H-rich envelope than for other type IIb SNe is considered (0.3 M☉). The hydrodynamical modelling of the LC and the comparison of our late-time spectra with nebular spectral models for type IIb SNe, point to a progenitor for SN 2011fu with a Zero Age Main Sequence (ZAMS) mass of 13–18 M☉.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat

SN 2011fu: a type IIb supernova with a luminous double-peaked light curve

We present optical and near-infrared observations of the type IIb supernova (SN) 2011fu from a few days to ∼300 d after explosion. The SN presents a double-peaked light curve (LC) similar to that of SN 1993J, although more luminous and with a longer cooling phase after the primary peak. The spectral evolution is also similar to SN 1993J’s, with hydrogen dominating the spectra to ∼40 d, then helium gaining strength, and nebular emission lines appearing from ∼60 d post-explosion. The velocities derived from the P-Cygni absorptions are overall similar to those of other type IIb SNe. We have found a strong similarity between the oxygen and magnesium line profiles at late times, which suggests that these lines are forming at the same location within the ejecta. The hydrodynamical modelling of the pseudo-bolometric LC and the observed photospheric velocities suggest that SN 2011fu was the explosion of an extended star (R ∼ 450 R☉), in which 1.3 × 1051 erg of kinetic energy were released and 0.15 M of 56Ni were synthesized. In addition, a better reproduction of the observed early pseudo-bolometric LC is achieved if a more massive H-rich envelope than for other type IIb SNe is considered (0.3 M☉). The hydrodynamical modelling of the LC and the comparison of our late-time spectra with nebular spectral models for type IIb SNe, point to a progenitor for SN 2011fu with a Zero Age Main Sequence (ZAMS) mass of 13–18 M☉.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat

Building the Arabic Learner Corpus and a System for Arabic Error Annotation

Recent developments in learner corpora have highlighted the growing role they play in some linguistic and computational research areas such as language teaching and natural language processing. However, there is a lack of a well-designed Arabic learner corpus that can be used for studies in the aforementioned research areas. This thesis aims to introduce a detailed and original methodology for developing a new learner corpus. This methodology which represents the major contribution of the thesis includes a combination of resources, proposed standards and tools developed for the Arabic Learner Corpus project. The resources include the Arabic Learner Corpus, which is the largest learner corpus for Arabic based on systematic design criteria. The resources also include the Error Tagset of Arabic that was designed for annotating errors in Arabic covering 29 types of errors under five broad categories. The Guide on Design Criteria for Learner Corpus is an example of the proposed standards which was created based on a review of previous work. It focuses on 11 aspects of corpus design criteria. The tools include the Computer-aided Error Annotation Tool for Arabic that provides some functions facilitating error annotation such as the smart-selection function and the auto-tagging function. Additionally, the tools include the ALC Search Tool that is developed to enable searching the ALC and downloading the source files based on a number of determinants. The project was successfully able to recruit 992 people including language learners, data collectors, evaluators, annotators and collaborators from more than 30 educational institutions in Saudi Arabia and the UK. The data of the Arabic Learner Corpus was used in a number of projects for different purposes including error detection and correction, native language identification, Arabic analysers evaluation, applied linguistics studies and data-driven Arabic learning. The use of the ALC highlights the extent to which it is important to develop this project