Damping of Electron Density Structures and Implications for Interstellar Scintillation

The forms of electron density structures in kinetic Alfven wave turbulence are studied in connection with scintillation. The focus is on small scales $L \sim 10^8-10^{10}$ cm where the Kinetic Alfv\'en wave (KAW) regime is active in the interstellar medium. MHD turbulence converts to a KAW cascade, starting at 10 times the ion gyroradius and continuing to smaller scales. These scales are inferred to dominate scintillation in the theory of Boldyrev et al. From numerical solutions of a decaying kinetic Alfv\'en wave turbulence model, structure morphology reveals two types of localized structures, filaments and sheets, and shows that they arise in different regimes of resistive and diffusive damping. Minimal resistive damping yields localized current filaments that form out of Gaussian-distributed initial conditions. When resistive damping is large relative to diffusive damping, sheet-like structures form. In the filamentary regime, each filament is associated with a non-localized magnetic and density structure, circularly symmetric in cross section. Density and magnetic fields have Gaussian statistics (as inferred from Gaussian-valued kurtosis) while density gradients are strongly non-Gaussian, more so than current. This enhancement of non-Gaussian statistics in a derivative field is expected since gradient operations enhance small-scale fluctuations. The enhancement of density gradient kurtosis over current kurtosis is not obvious, yet it suggests that modest fluctuation levels in electron density may yield large scintillation events during pulsar signal propagation in the interstellar medium. In the sheet regime the same statistical observations hold, despite the absence of localized filamentary structures. Probability density functions are constructed from statistical ensembles in both regimes, showing clear formation of long, highly non-Gaussian tails

The water-cryogen heat exchanger

Heat exchanger, using water as heat medium, converts liquid hydrogen to gaseous hydrogen at a very high rate. Possible applications include treatment of liquified natural gas in cities to bring the gas on-line quickly, conversion of liquid oxygen and liquid nitrogen for steel mills, and high volume inert purging

After Columbus: Explaining the Global Trade Boom 1500-1800

This paper documents the size and timing of the world inter-continental trade boom following the great voyages in the 1490s of Columbus, da Gama and their followers. Indeed, a trade boom followed over the subsequent three centuries. But what was its cause? The conventional wisdom in the world history literature offers globalization as the answer: it alleges that declining trade barriers, falling transport costs and overseas "discovery" explains the boom. In contrast, this paper reports the evidence that confirms unambiguously that there was no commodity price convergence between continents, something that would have emerged had globalization been a force that mattered. Thus, the trade boom must have been caused by some combination of European import demand and foreign export supply from Asia and the Americas. Furthermore, the behavior of the relative price of foreign importables in European cities should tell us which mattered most and when. We offer detailed evidence on the relative prices of such importables in European markets over the five centuries 1350-1850. We then offer a model which is used to decompose the sources of the trade boom 1500-1800.

After Columbus: Explaining the Global Trade Boom 1500-1800

This paper documents the size and timing of the world inter-continental trade boom following the greate voyages in the 1490s of Columbus, da Gama and their followers. Indeed, a trade boom followed over the subsequent three centuries. But what was its cause? The conventionnal wisdom in the world history literature offers globalization as the answer: it alleges that declining trade barriers falling transport costs and overseas "discovery" explains the boom. In contrast, this paper reports the evidence that confirms unambiguously that there was no commodity price convergence between continents, something that would have emerged had globalization been a force that mattered. Thus, the trade boom must have been caused by some combination of European import demand and foreign export supply from Asia and the Americas. Furthermore, the behavior of the relative price of foreign importables in European cities should tell us which mattered most and when. We offer detailed evidence on the relative prices of such importables in European markets over the five centuries 1350-1850. We then offer a model which is used to decompose the sources of the trade boom 1500-1800.

Seeing the music in their hands: How conductors' depictions shape the music

Depiction is a way of ‘showing’ meaning through certain gestures or demonstrations. Conductors often use depiction, including multimodal depiction, as well as descriptive talk, to convey meaning to their choirs. This paper considers four short extracts from choir rehearsals with different conductors, to show how they combine description and depiction, including vocal models, facial expressions, metaphoric and iconic gestures and body language to communicate about music, specifically here as part of the activity of modelling

The influence of siblings on young children's understanding of fluid intake

BACKGROUND: Children need to drink enough water (1.1-1.3 litres) throughout the day to stay hydrated and for health benefits1. Wellbeing and cognitive function benefits have been identified for children who are hydrated2. Yet there is a dearth of research focusing specifically on children’s perceptions of their own fluid intake levels and who helps support them in ensuring they are drinking enough water, this is a novel area to investigate. Previous research3 identified that 44.2% of young children’s fluid intake were influenced the strongest by a family member. This paper will explore in further detail the influence of siblings on children’s fluid intake, in particular older versus younger siblings. METHODS: 130 children (67 girls and 63 boys, of which 45 had a younger sibling (s) and 85 having an elder sibling (s), from 4 primary schools in the South East of England, were questioned between January and April 2019 using an adapted version of Coppinger and Howells’ (2019)4 questionnaire, on their understanding of fluid intake, how much they perceived they drank and who supported them in prompting them to drink. Physical visual representations were used to aid question comprehension and to ensure the questions were appropriate for young children. The data was analysed using SPSS 24.0 using MANOVAs (P < 0.05) to consider statistical variance in gender and older sibling status. RESULTS: The most significant results were linked to elder siblings influence younger siblings in drinking too little fluids within a school day (F=0.530, p<0.05), whilst those without an elder sibling, thought they drank beyond the daily recommended guidelines and reported they drank over 2 litres. This illustrates that children misunderstand fluid intake recommendations regardless of whether they have an elder sibling or not. Children named adults, both parents and teachers as well as elder siblings as the key influencers of them drinking (F=3.67, p<0.05) and the data indicated that girls were more influenced by siblings than boys, whilst twins were not influenced by each other. CONCLUSION: It is concluded that siblings do have an influence on the consumption of water, as siblings act as role models and other siblings follow their habits, therefore the whole family unit is important to ensure that the right fluid intake is consumed. It is recommended that further education, curriculum and community development is needed to continue to support young children’s knowledge and understanding of fluid intake

4 and 5 year olds' understanding of fluid intake within England

Background: Within the England children start school in the September following their fourth birthday. Within the preschool school setting and within the first year of primary school the same early years’ foundation stage curriculum is followed (DfE, 2013). Within this curriculum children are to learn about the importance for good health of physical exercise, and a healthy diet. Previously, Coppinger and Howells’ (2019) completed an international comparison between primary schools in Ireland and England focusing on children’s understanding of fluid intake and found that children under 11 years did not understand the amount of fluid that is needed each day for good health, however, they only had a small sample of children from the 4 – 5 age category. This paper focuses solely on this youngest age range within England’s context of primary (elementary) school as a focused analysis. Methods: The questionnaire used by Coppinger and Howells in their research has been adapted to be aged appropriate for use for 4 and 5 year olds, including physical visual representations to aid understanding of the younger age group. 130 children from 5 different schools, in the same geographical location, were questioned as to their understanding of fluid intake, when they are allowed to drink within the school setting, the barriers that prevent them from drinking and who influences and encourages their fluid intake. Results and Conclusion: Data will be presented according to age, and gender. Data collection was undertaken between January and April 2019. It is hypothesised that the age range of 4 and 5 year olds will not understanding their daily fluid intake needs. It is proposed that this research will give insight to help teachers and practitioners identify what is the current understanding of this age range and how educational materials could help the children, teachers and parents develop the children’s knowledge to drink healthily

Young children's understanding of fluid intake

BACKGROUND Coppinger and Howells’ (2019) previously completed an International comparison between primary schools in Ireland and England focusing on children’s understanding of fluid intake. They identified that children under 11 years did not understand the amount of fluid they need each day for good health. Within their sample there was only a limited number of children who were aged 4 – 5 years. This research focuses on this particular age phase and further questions if young children understand fluid intake. METHODS 130 children (63 boys and 67 girls, of which 83 were aged 4 and 47 were aged 5) from 4 elementary schools in the South East of England were questioned between January and April 2019 using an adapted version of Coppinger and Howells’ (2019) questionnaire on their understanding of fluid intake and how much they perceived they drank and who supported them in prompting them when to drink. The adaptions were to ensure the questionnaire was age appropriate for younger age range, and included physical visual representations to aid question comprehension. RESULTS 46.9% of children felt they consumed 500ml or under a day. Only 39.6% responded that they were supported by the teacher, also when children were thirsty, if given the option of playing or stopping rehydration and then playing 33.8% would continue to play without drinking. CONCLUSION Young children in England do not understand fluid recommendations, they were not supported within the school setting by their teacher and more effective resources and strategies are needed to support children’s knowledge