Deep Metric Learning via Facility Location

Learning the representation and the similarity metric in an end-to-end fashion with deep networks have demonstrated outstanding results for clustering and retrieval. However, these recent approaches still suffer from the performance degradation stemming from the local metric training procedure which is unaware of the global structure of the embedding space. We propose a global metric learning scheme for optimizing the deep metric embedding with the learnable clustering function and the clustering metric (NMI) in a novel structured prediction framework. Our experiments on CUB200-2011, Cars196, and Stanford online products datasets show state of the art performance both on the clustering and retrieval tasks measured in the NMI and Recall@K evaluation metrics.Comment: Submission accepted at CVPR 201

Improved and Quality-assessed Emission and Absorption Line measurements in Sloan Digital Sky Survey galaxies

We present a new database of absorption and emission-line measurements based on the entire spectral atlas from the Sloan Digital Sky Survey (SDSS) 7th data release of galaxies within a redshift of 0.2. Our work makes use of the publicly available penalized pixel-fitting(pPXF) and gas and absorption line fitting (gandalf) IDL codes, aiming to improve the existing measurements for stellar kinematics, the strength of various absorption-line features, and the flux and width of the emissions from different species of ionised gas. Our fit to the stellar continuum uses both standard stellar population models and empirical templates obtained by combining a large number of stellar spectra in order to fit a subsample of high-quality SDSS spectra for quiescent galaxies. Furthermore, our fit to the nebular spectrum includes an exhaustive list of both recombination and forbidden lines. Foreground Galactic extinction is implicitly treated in our models, whereas reddening in the SDSS galaxies is included in the form of a simple dust screen component affecting the entire spectrum that is accompanied by a second reddening component affecting only the ionised gas emission. In order to check for systematic departures, we provide a quality assessment for our fit to the SDSS spectra in our sample. This quality assessment also allows the identification of objects with either problematic data or peculiar features. For example, based on the quality assessment, approximately 1% of the SDSS spectra classified as "galaxies" by the SDSS pipeline do in fact require additional broad lines to be matched, even though they do not show a strong continuum from an active nucleus, as do the SDSS objects classified as "quasars". Finally, we provide new spectral templates for galaxies of different Hubble types, obtained by combining the results of our spectral fit for a subsample of 452 morphologically selected objects.Comment: Accepted for publication in ApJS. 23 pages, 14 figures, 4 tables. A version with high-resolution figures is available at http://gem.yonsei.ac.kr/~ksoh/ossy/arXiv/Oh_11_OSSY.pd

The Effects of Professional Development on Co-Teaching for Special and General Education Teachers and Students

As we progress into a future where more students with IEPs are in general education classes, teachers must be innovative, creative, and passionate about providing an opportunity for all students to succeed in the classroom. Rather than students with IEPs be taken from their classrooms to receive remedial services from their special education teacher, it is more beneficial to all students and teachers to have education specialists and general education teachers co-teach classes (Conderman, 2011). Education specialists have extensive knowledge in acquisition of literacy skills, how to scaffold, and present information through multiple mediums. General education teachers are experts in their content areas, and are effective in delivering instruction to an audience of learners with different needs. Together, they can learn from each other to create a more enriched learning environment where all students can succeed. This study examined the pre and post surveys of 35 (15 special education and 20 general education) middle school students and 22 teachers about their experiences with co-teaching

Challenging, eye-opening, and changing U.S. teacher training in Korea: Creating experiences that will enhance global perspectives

This case study explored the short-term international experience of preservice teachers to create and enhance global perspectives. These teachers (n=5), all female graduate students at a university in the U.S., were fully immersed in a foreign culture for three weeks while teaching English to primary and secondary students in Korea. Pre-, during-, and post-data were collected to investigate how the participants work and live while being completely immersed in a new culture. Eight themes emerged from the analysis of multiple qualitative instruments: (a) language barrier, (b) being the minority, (c) cultural differences and cultural shock, (d) student participation and teaching methods, (e) classroom management, (f) underestimation of English language learners, (g) finding confidence as a teacher and instructional flexibility, and (h) support systems. Overall, teachers expressed a transformation in both their teaching philosophy and cultural perspectives despite the short duration of the experience. They also reported that this linguistic and cultural immersion not only advanced their global perspective but also provided them with the necessary tools and understanding to work with diverse populations more emphatically and effectively. The findings suggest that additional teacher training is needed to increase preservice teachers’ cultural competence and responsiveness to better address the needs of today’s diverse student populations

Teacher training in the use of a three-dimensional immersive virtual world: Building understanding through first-hand experiences

This study offers recommendations and a model for other teacher educators who are interested in training teachers in the use of three-dimensional (3D) immersive virtual worlds (IVWs) for their own teaching. Twelve special education teachers collaboratively explored the usability of Second Life (SL) for special education by completing a full inquiry cycle to develop the ability to make informed decisions about the affordances and challenges of virtual world teaching and to help identify effective components for virtual worlds teacher training. Ten educational SL islands were explored critically. Mixed-methods data analysis and triangulation were based on the analysis and synthesis of a preliminary survey, a mid-reflection after several virtual explorations, the collaborative analysis of an existing SL lesson plan, the collaborative development of a SL lesson plan, a post-reflection, and a post-survey. Several key benefits of 3D IVWs for special education students emerged from the qualitative analyses, namely social skills practice, collaborative learning towards a joint goal with a competitive element, and increased motivation to participate, especially for topics that would otherwise be perceived as boring. The qualitative data informed the development of guidelines for virtual worlds teacher training and the elements of an ideal SL island designed for special education. The change of attitude towards the usability of virtual worlds in education as a result of the workshop was not statistically significant

Stability and asymptotic behavior of periodic traveling wave solutions of viscous conservation laws in several dimensions

Under natural spectral stability assumptions motivated by previous investigations of the associated spectral stability problem, we determine sharp $L^p$ estimates on the linearized solution operator about a multidimensional planar periodic wave of a system of conservation laws with viscosity, yielding linearized $L^1\cap L^p\to L^p$ stability for all $p \ge 2$ and dimensions $d \ge 1$ and nonlinear $L^1\cap H^s\to L^p\cap H^s$ stability and $L^2$-asymptotic behavior for $p\ge 2$ and $d\ge 3$. The behavior can in general be rather complicated, involving both convective (i.e., wave-like) and diffusive effects

Turing patterns in parabolic systems of conservation laws and numerically observed stability of periodic waves

Turing patterns on unbounded domains have been widely studied in systems of reaction-diffusion equations. However, up to now, they have not been studied for systems of conservation laws. Here, we (i) derive conditions for Turing instability in conservation laws and (ii) use these conditions to find families of periodic solutions bifurcating from uniform states, numerically continuing these families into the large-amplitude regime. For the examples studied, numerical stability analysis suggests that stable periodic waves can emerge either from supercritical Turing bifurcations or, via secondary bifurcation as amplitude is increased, from sub-critical Turing bifurcations. This answers in the affirmative a question of Oh-Zumbrun whether stable periodic solutions of conservation laws can occur. Determination of a full small-amplitude stability diagram-- specifically, determination of rigorous Eckhaus-type stability conditions-- remains an interesting open problem.Comment: 12 pages, 20 figure