Ground-based adaptive optics coronagraphic performance under closed-loop predictive control

The discovery of the exoplanet Proxima b highlights the potential for the coming generation of giant segmented mirror telescopes (GSMTs) to characterize terrestrial --- potentially habitable --- planets orbiting nearby stars with direct imaging. This will require continued development and implementation of optimized adaptive optics systems feeding coronagraphs on the GSMTs. Such development should proceed with an understanding of the fundamental limits imposed by atmospheric turbulence. Here we seek to address this question with a semi-analytic framework for calculating the post-coronagraph contrast in a closed-loop AO system. We do this starting with the temporal power spectra of the Fourier basis calculated assuming frozen flow turbulence, and then apply closed-loop transfer functions. We include the benefits of a simple predictive controller, which we show could provide over a factor of 1400 gain in raw PSF contrast at 1 $\lambda/D$ on bright stars, and more than a factor of 30 gain on an I = 7.5 mag star such as Proxima. More sophisticated predictive control can be expected to improve this even further. Assuming a photon noise limited observing technique such as High Dispersion Coronagraphy, these gains in raw contrast will decrease integration times by the same large factors. Predictive control of atmospheric turbulence should therefore be seen as one of the key technologies which will enable ground-based telescopes to characterize terrrestrial planets.Comment: Accepted to JATI

What do teachers attend to in curriculum materials?

In this paper, we describe an emerging methodology using eye tracking to explore teachers’ curricular attending as they interact with curriculum materials to design a lesson in order to learn what teachers pay attention to and how this attention shifts during planning. We propose affordances of this new method, remark on some of its limitations, and propose future directions

On tt-core and self-conjugate (2t−1)(2t-1)-core partitions in arithmetic progressions

We extend recent results of Ono and Raji, relating the number of self-conjugate $7$-core partitions to Hurwitz class numbers. Furthermore, we give a combinatorial explanation for the curious equality $2\operatorname{sc}_7(8n+1) = \operatorname{c}_4(7n+2)$. We also conjecture that an equality of this shape holds if and only if $t=4$, proving the cases $t\in\{2,3,5\}$ and giving partial results for $t>5$

Youth Health Services, Development Programs, and Teenage Birth Rates in 55 California Cities

Many advocacy groups depict sexuality education, abstinence education, health services, and development services to teenagers as pivotal factors in their birth rates. Data from California’s 55 largest cities for 1990-2002 allow regression analyses of the associations between levels of health and development services to youth, socioeconomic factors such as poverty, and environmental factors such adult birth rates on rates of and changes in births to teenage mothers. The analysis found teenage birth rates vary 30-fold from California’s richest to poorest city. Socioeconomic and environmental factors, chiefly adult birth rates and youth poverty rates, are associated with nearly 90% of the variance in teen birth rates. Contrary to assertions by many advocates, lower-income teens have greater access to health, sexuality education, and development services, and the availability of these services is not associated with lower rates of or greater reductions over time in teenage birth rates

One-to-one laptop program: Effect on boys\u27 education

Since the beginning of 1:1 laptop programs in schools there has been extensive research undertaken about the effectiveness of how laptops are used for teaching and learning. With an educational environment in Australia where the use of Information Communications Technology (ICT) is one of the five general capabilities of the Australian Curriculum, an expectation to use ICT effectively for teaching and learning is explicit. However, the use of laptops for teaching and learning is complex for teachers and students. Furthermore, parents are expected to support their child’s learning in a digital age where mobile devices for learning are common. Therefore, investigating parental involvement and perceptions was a significant feature of the study. This report presents a three-year longitudinal study that examined the implementation of a student-owned 1:1 laptop program in a school for boys in Perth, Western Australia. The research tracked 196 students drawn from the junior (primary) and middle (secondary) schools, their families and associated teachers for a three year period. The focus on male students is purposeful. Understanding how male students use their laptops for learning can provide useful insights into the affordances and risks for schools and, in particular, the field of boys’ education. The aim of the research, therefore, was to describe and explain how boys use their laptops for learning in primary and middle school settings. Involving the whole school community in the research allowed for rich description and hopefully insightful explanation. The research literature reports that the use of laptops for learning can increase motivation and engagement, improve technology proficiencies, provide enriched learning experiences, and help teaching and learning. The five research questions developed to guide the research were aimed at either endorsing or challenging these claims. Underpinning this research was a mixed methods approach investigating how the boys used their laptops for learning, teachers’ pedagogical uses of laptops, implementation differences between a junior and middle school, and the possible impact of the laptops on literacy and numeracy outcomes. A rich data set, collected over three years, and derived from qualitative and quantitative techniques, was interrogated in relation to the study’s research questions. The study’s longitudinal design provided further opportunities to triangulate data over the three years, enhancing the strength and reliability of the findings. The novelty factor of laptops for learning quickly abated for both junior and middle school students. A two-pronged approach of providing targeted professional learning for staff coupled with confronting the obvious distraction that a 1:1 device can be for primary and middle school students, yielded positive outcomes. Students held strong views about the role, and effectiveness of a teacher when utilising their laptops for learning. Although teachers reported laptops were important for the teaching and learning program, there was a wide variation in the way teachers harnessed the 1:1 laptop environment for the benefit for student learning. Also, teachers were faced with pedagogical challenges in terms of considering games or Web 2.0 for learning. Literacy and numeracy outcomes based on national assessment results compared to national standards revealed the case study student participants performed favourably. Four enablers for effective laptop use are theorised. These are: inquisitive students, creative teachers, proactive leaders, and national and state policy directions. However, five paradoxes potentially inhibited these enablers. These paradoxes are presented as ‘spanners’ in the cogs of effective 1:1 laptop initiatives: engagement and seduction of students; transformative and conservative pedagogical practices; integration and alienation of parents; autonomy and systemic dependency of schools; and, the hope and fear of Web 2.0. The study may assist educational policy-makers, school leaders and teachers who are contemplating how to best integrate 1:1 laptop devices into the fabric of schools. A model is presented to provide new knowledge about the impacts of 1:1 devices on teaching and learning