Energy shedding during nonlinear self-focusing of optical beams

Self-focusing of intense laser beams and pulses of light in real nonlinear media is in general accompanied by material losses that require corrections to the conservative Nonlinear Schrödinger equations describing their propagation. Here we examine loss mechanisms that exist even in lossless media and are caused by shedding of energy away from the self-trapping beam making it to relax to an exact solution of lower energy. Using the conservative NLS equations with absorbing boundary conditions we show that energy shedding not only occurs during the initial reshaping process but also during oscillatory propagation induced by saturation of the nonlinear effect. For pulsed input we also show that, depending on the sign and magnitude of dispersion, pulse splitting, energy shedding, collapse or stable self-focusing may result

Negotiating difference through research and teaching strategies in China and Australia

In the seminar, we will identify the process and challenges of conducting this research, and highlight some of the key findings. We will argue that disparate pedagogical strategies exist in China and Australia with consequences for the lecturer - student relationship in Australia, and the success or otherwise of Chinese students studying communication, media and management. If time allows, we will also work through some of the socially, culturally and educationally responsible pedagogical strategies and innovative resources devised by the project specifically to address this situation

An agenda for change: Supporting Chinese postgraduate students studying media and communication in Australia

Recent years have seen increasing educational ties between China and Australia. Australian government statistics report that 40.6% of international students studying at tertiary level in May 2012 came from China (AEI, 2012). This situation has prompted many Australian and Chinese universities, including Schools of Media and Communication, to actively seek to develop mutually advantageous partnering opportunities within the globali sed education market..

Managing academic skills development and english language learning and use: The case Of Chinese postgraduate coursework students studying in Australia

The challenges confronting Chinese students studying in Anglophone universities are well documented (e.g. Durkin, 2008; Huang, 2008; Ryan, 2010). Effective communication in English across different language modes and through different text-types is identified as problematic. In response, and in order to support Chinese and other international students in their learning, arguments have been made for the adoption by academics in Anglo-European universities of pedagogies that are culturally inclusive (Jackson, Watty, Yu, & Lowe, 2006), blended (Zhu, 2010), and/or open-ended (Sharma, 2006). Discussion and actions associated with the uses of such pedagogies are directed towards honouring students’ home languages and cultures, and have the aim of benefiting a universal student body. Whilst such aspirations and actions are no doubt both admirable and honourable, this paper argues that notions of inclusivity and blending may be incommensurable with the disparate pedagogical strategies that exist in China and Australia. It is therefore incumbent on academics in Australia to devise and adopt approaches that make explicit ‘difference’ in terms of disparate educational contexts, the often conflictual learning expectations and the different disciplinary discourses and text types which Chinese students, particularly those involved in postgraduate coursework programs, are required to both negotiate and perform in their studies in Australia. This paper reports on the early findings of a collaborative project between two Chinese and five Australian universities where qualitative research has been conducted in both countries in order to identify and articulate how approaches which are socially, culturally and educationally responsible might be developed to support Chinese postgraduate coursework students. Findings indicate that factors such as established understandings of university discourses, and compressed timeframes for study necessitate explicit articulation and negotiation of difference as a mechanism to support Chinese students

Collaborating for Success: Enhancing the transition of Chinese communication/media students into Australian postgraduate education

This international project involved three partner universities -­‐ Murdoch University, Victoria University and Communication University of China – and a range of other higher education institutions in Australia and China. The project sought to enhance the capacity of academics and institutions in Australia and China in intercultural competency, learning support, and international collaboration and has been successful in achieving this. As a result, on postgraduate media and communication courses associated with the project students from mainland China who are studying in Australia have begun to develop proficiency in negotiating between different academic cultures and therefore are better equipped to be successful learners in the Australian academic context. Academics in Australia and China have gained a greater understanding of cultural difference and how this influences student learning, notably during their transition from study in China to postgraduate study in Australia. The project has strengthened established international partnerships and stimulated new international relationships in higher education and industry. In the Australian partner institutions, there is evidence of an increase in capacity to provide quality international education together with more effective support for Chinese students in their transition into Australian postgraduate study. ... The project has made and will continue to make a significant contribution to knowledge in a number of important areas. These include knowledge about mainland China’s education philosophy, pedagogical practices, learning behaviours and expectations, and a recommended approach to constructing and adapting research-­‐based resources for the international learning and teaching arena. It has also advanced knowledge about the types of pedagogical strategies and resources that are effective in supporting Chinese students on their journey towards becoming proficient learners on Australian postgraduate courses in media and communication

Comment on "Self-Purification in Semiconductor Nanocrystals"

In a recent Letter [PRL 96, 226802 (2006)], Dalpian and Chelikowsky claimed that formation energies of Mn impurities in CdSe nanocrystals increase as the size of the nanocrystal decreases, and argued that this size dependence leads to "self-purification" of small nanocrystals. They presented density-functional-theory (DFT) calculations showing a strong size dependence for Mn impurity formation energies, and proposed a general explanation. In this Comment we show that several different DFT codes, pseudopotentials, and exchange-correlation functionals give a markedly different result: We find no such size dependence. More generally, we argue that formation energies are not relevant to substitutional doping in most colloidally grown nanocrystals.Comment: 1 page, 1 figur

Effective speed of sound in phononic crystals

A new formula for the effective quasistatic speed of sound $c$ in 2D and 3D periodic materials is reported. The approach uses a monodromy-matrix operator to enable direct integration in one of the coordinates and exponentially fast convergence in others. As a result, the solution for $c$ has a more closed form than previous formulas. It significantly improves the efficiency and accuracy of evaluating $c$ for high-contrast composites as demonstrated by a 2D example with extreme behavior.Comment: 4 pages, 1 figur

A tale of one city: intra-institutional variations in migrating VLE platform

City University London committed in 2009 to make Moodle the Virtual Learning Environment (VLE) at the core of a new Strategic Learning Environment (SLE) comprised of VLE, externally facing website and related systems such as video streaming and virtual classrooms. Previously, the WebCT VLE had been separate from most of the other systems at the institution with very limited connections to other tools. Each of the schools within the institution was able to pursue their own strategy and timeframe for the migration and embedding of Moodle within their subject areas, within an absolute limit of 2 years. This paper outlines the approaches taken by the various schools, highlighting similarities and differences, and draws out common aspects from the project to make recommendations for institutions seeking to undertake similar migrations

Current understanding of the role of manganese in nutrition

Cover title."A lecture given at Nutrition Emphasis Week, University of Missouri, February 19-21, 1969"--P. [1].Includes bibliographical references (pages 10-14)

Solar Irradiance Variability is Caused by the Magnetic Activity on the Solar Surface

The variation in the radiative output of the Sun, described in terms of solar irradiance, is important to climatology. A common assumption is that solar irradiance variability is driven by its surface magnetism. Verifying this assumption has, however, been hampered by the fact that models of solar irradiance variability based on solar surface magnetism have to be calibrated to observed variability. Making use of realistic three-dimensional magnetohydrodynamic simulations of the solar atmosphere and state-of-the-art solar magnetograms from the Solar Dynamics Observatory, we present a model of total solar irradiance (TSI) that does not require any such calibration. In doing so, the modeled irradiance variability is entirely independent of the observational record. (The absolute level is calibrated to the TSI record from the Total Irradiance Monitor.) The model replicates 95% of the observed variability between April 2010 and July 2016, leaving little scope for alternative drivers of solar irradiance variability at least over the time scales examined (days to years).Comment: Supplementary Materials; https://journals.aps.org/prl/supplemental/10.1103/PhysRevLett.119.091102/supplementary_material_170801.pd