Inside-out growth or inside-out quenching? clues from colour gradients of local galaxies

We constrain the spatial gradient of star formation history within galaxies using the colour gradients in NUV-u and u-i for a local spatially-resolved galaxy sample. By splitting each galaxy into an inner and an outer part, we find that most galaxies show negative gradients in these two colours. We first rule out dust extinction gradient and metallicity gradient as the dominant source for the colour gradient. Then using stellar population models, we explore variations in star formation history to explain the colour gradients. As shown by our earlier work, a two-phase SFH consisting of an early secular evolution (growth) phase and a subsequent rapid evolution (quenching) phase is necessary to explain the observed colour distributions among galaxies. We explore two different inside-out growth models and two different inside-out quenching models by varying parameters of the SFH between inner and outer regions of galaxies. Two of the models can explain the observed range of colour gradients in NUV-u and u-i colours. We further distinguish them using an additional constraint provided by the u-i colour gradient distribution, under the assumption of constant galaxy formation rate and a common SFH followed by most galaxies. We find the best model is an inside-out growth model in which the inner region has a shorter e-folding time scale in the growth phase than the outer region. More spatially resolved ultraviolet (UV) observations are needed to improve the significance of the result.Comment: 11 pages, 7 figures, accepted for publication in MNRA

Mobile Learning in Civil Servant English Proficiency Training: Advantages, Challenges, and Implementation

This study takes Hainan Free Trade Port as the background to explore the potential and applicability of mobile learning in improving civil servants' English proficiency. While mobile learning offers many advantages, such as flexibility, convenience, personalization and collaborative learning opportunities, there are still challenges that need to be addressed, including technology infrastructure, data security and digital literacy. Using a specially designed WeChat E-learning training program as an illustrative case, the paper demonstrates how mobile platforms can cater to the unique English training needs of civil servants. This tailored program focuses on individualized learning, interactive sessions, and the establishment of a learning community, aiming to improve their intercultural communication skills crucial for international collaborations. The study highlights that while mobile learning shows great promise in the field of English training for civil servants, adequate support, resources, and optimal integration with traditional training methods are essential to take full advantage of its benefits. In addition, the study points to the need to explore innovative strategies for optimizing mobile learning experiences in the future and assess their long-term impact on civil service performance