The Efficiency of Magnetic Field Amplification at Shocks by Turbulence

Turbulent dynamo field amplification has often been invoked to explain the strong field strengths in thin rims in supernova shocks ($\sim 100 \, \mu$G) and in radio relics in galaxy clusters ($\sim \mu$G). We present high resolution MHD simulations of the interaction between pre-shock turbulence, clumping and shocks, to quantify the conditions under which turbulent dynamo amplification can be significant. We demonstrate numerically converged field amplification which scales with Alfv\'en Mach number, $B/B_0 \propto {\mathcal M}_{\rm A}$, up to ${\mathcal M}_{\rm A} \sim 150$. This implies that the post-shock field strength is relatively independent of the seed field. Amplification is dominated by compression at low ${\mathcal M}_{\rm A}$, and stretching (turbulent amplification) at high ${\mathcal M}_{\rm A}$. For high $\mathcal{M}_{\rm A}$, the $B$-field grows exponentially and saturates at equipartition with turbulence, while the vorticity jumps sharply at the shock and subsequently decays; the resulting field is orientated predominately along the shock normal (an effect only apparent in 3D and not 2D). This agrees with the radial field bias seen in supernova remnants. By contrast, for low $\mathcal{M}_{\rm A}$, field amplification is mostly compressional, relatively modest, and results in a predominantly perpendicular field. The latter is consistent with the polarization seen in radio relics. Our results are relatively robust to the assumed level of gas clumping. Our results imply that the turbulent dynamo may be important for supernovae, but is only consistent with the field strength, and not geometry, for cluster radio relics. For the latter, this implies strong pre-existing $B$-fields in the ambient cluster outskirts.Comment: 15 pages, 11 figures, published version on MNRA

The Impact of sex-separate toilets on school participation of pubescent-age girls in India

Thesis(Master) -- KDI School: Master of Development Policy, 2020The issue of sanitation is related to the academic achievement of students in developing countries. Above all, sex-separate sanitation facilities in schools play a crucial role when it comes to students’ ability to focus on their studies, particularly for girls just at the beginning of puberty. This paper examines the association between girls’ toilets and school participation by adolescent girls in India using a state-level panel data set. To control for potential omitted variables bias, I adopt state fixed effects among control variables. I have two major findings. First, schools with sex-separate toilets are associated with a higher level of girls’ enrolment at the secondary and the higher secondary level. Second, schools with sex-separate toilets are also associated with a higher level of school attendance by girls at the secondary level.INTRODUCTION THEORY AND RESEARCH QUESTIONS METHODS FINDINGS CONCLUSIONmasterpublishedHyun Ji O

Understanding teachers' beliefs of young children's play in naturalized learning environments.

Recent research in the field of early childhood education has increasingly focused on children's connections with natural environments. However, there has yet to be a study that investigates teachers' perceptions of teaching young children and the impact on their learning utilizing natural environments during early childhood, which is precisely the aim of this research. Such a study is needed to attain authentic information about possible connections between teachers' personal experiences, their perspectives and their practices regarding teaching and learning in naturalized environments. This qualitative research study is composed of two major components: in-depth teacher interviews and an outdoor and indoor environment checklist. The in-depth teacher interviews document teachers' personal play histories, their ways of implementing children's play in naturalistic settings, and their beliefs about the value of children's play in naturalized environments. The environment checklist is used to examine the enriched naturalized environments that are provided indoors and outdoors to help children interact with the natural world. Four major themes were identified and several conclusions were drawn from the data. First, teachers' beliefs about naturalized environments are consistent with their teaching practice in those environments. Second, teachers who are teaching in naturalistic environment schools value the natural environment. Third, teachers' personal life experiences influence their perceptions of teaching and learning in naturalized environments. Fourth, teachers' perceptions regarding the value of naturalistic environments for children's learning were that creative thinking, problem solving, and more in-depth learning occurred

The Challenges of Supporting Young Children’s Outdoor Play in Early Childhood Education and Care Settings

This study explored preschool teachers’ beliefs about the challenges they have experienced when supporting young children’s outdoor play. Through Charmaz’s (2006) constructivist grounded theory data analysis process, two types of challenges for providing outdoor play were specified including: (1) natural environmental challenges, such as insect bites, allergies, and severe weather issues and (2) physical environmental challenges that include lack of play materials/environments and playground maintenance. The participant teachers perceive that these challenges are related to their preparation and planning for outdoor play including the provision of outdoor play, allotted play time, and a number of outdoor learning activities

Pediatric asthma and autism-genomic perspectives.

High-throughput technologies, ranging from microarrays to NexGen sequencing of RNA and genomic DNA, have opened new avenues for exploration of the pathobiology of human disease. Comparisons of the architecture of the genome, identification of mutated or modified sequences, and pre-and post- transcriptional regulation of gene expression as disease specific biomarkers are revolutionizing our understanding of the causes of disease and are guiding the development of new therapies. There is enormous heterogeneity in types of genomic variation that occur in human disease. Some are inherited, while others are the result of new somatic or germline mutations or errors in chromosomal replication. In this review, we provide examples of changes that occur in the human genome in two of the most common chronic pediatric disorders, autism and asthma. The incidence and economic burden of both of these disorders are increasing worldwide. Genomic variations have the potential to serve as biomarkers for personalization of therapy and prediction of outcomes

Applying event-related potentials to measure consumer preferences for apparel products

By analyzing ERP waveforms generated by sensory and cognitive processing of external stimuli, the researchers attempted to observe how consumers respond emotionally to apparel products and to explain why they responded as they did. In this research, ERPs were applied to explore consumers\u27 subconscious, real-time emotional responses to apparel products. Overall, the favored shirts produced more enhanced ERP amplitude at the FZ, CA, and PZ site than the less favored shirts supporting the hypothesis. As this shows, the P3 and LPP components can be evoked by emotional visual stimuli. More positive-going ERP waves are associated with favorable and pleasant responses to the visual stimuli. Apparel companies would be able to utilize this ERP technique especially the P3 and LPP component to verify consumer preferences