The periodic standing-wave approximation: nonlinear scalar fields, adapted coordinates, and the eigenspectral method

The periodic standing wave (PSW) method for the binary inspiral of black holes and neutron stars computes exact numerical solutions for periodic standing wave spacetimes and then extracts approximate solutions of the physical problem, with outgoing waves. The method requires solution of a boundary value problem with a mixed (hyperbolic and elliptic) character. We present here a new numerical method for such problems, based on three innovations: (i) a coordinate system adapted to the geometry of the problem, (ii) an expansion in multipole moments of these coordinates and a filtering out of higher moments, and (iii) the replacement of the continuum multipole moments with their analogs for a discrete grid. We illustrate the efficiency and accuracy of this method with nonlinear scalar model problems. Finally, we take advantage of the ability of this method to handle highly nonlinear models to demonstrate that the outgoing approximations extracted from the standing wave solutions are highly accurate even in the presence of strong nonlinearities.Comment: RevTex, 32 pages, 13 figures, 6 table

Is Love All You Need?

This project investigates Harry Frankfurt’s work on love and its role in his model of practical reason. Specifically, it identifies a number of shortcomings in Frankfurt’s view focused on his dismissal of objective practical value, putting all such value in terms of personal commitment to what one loves. In other words, this project finds fault in the claim that “love is all you need” to construct a compelling model of practical reason. However, I find that his model can overcome these shortcomings if it can be extended to include non-personal sources of practical value. I conclude by suggesting just such a source: if his view can be made to recognize objective practical value like autonomy, it would address my concerns while hopefully remaining true to the original spirit of the work

Statistical modelling of air quality impacts from individual forest fires in New South Wales, Australia

Wildfires and hazard reduction burns produce smoke that contains pollutants including particulate matter. Particulate matter less than 2.5 µm in diameter (PM2.5) is harmful to human health, potentially causing cardiovascular and respiratory issues that can lead to premature deaths. PM2.5 levels depend on environmental conditions, fire behaviour and smoke dispersal patterns. Fire management agencies need to understand and predict PM2.5 levels associated with a particular fire so that pollution warnings can be sent to communities and/or hazard reduction burns can be timed to avoid the worst conditions for PM2.5 pollution. We modelled PM2.5, measured at air quality stations in New South Wales (Australia) from ∼ 1400 d when individual fires were burning near air quality stations, as a function of fire and weather variables. Using Visible Infrared Imaging Radiometer Suite (VIIRS) satellite hotspots, we identified days when one fire was burning within 150 km of at least 1 of 48 air quality stations. We extracted ERA5 gridded weather data and daily active fire area estimates from the hotspots for our modelling. We created random forest models for afternoon, night and morning PM2.5 levels to understand drivers of and predict PM2.5. Fire area and boundary layer height were important predictors across the models, with temperature, wind speed and relative humidity also being important. There was a strong increase in PM2.5 with decreasing distance, with a sharp increase when the fire was within 20 km. The models improve our understanding of the drivers of PM2.5 from individual fires and demonstrate a promising approach to PM2.5 model development. However, although the models predicted well overall, there were several large under-predictions of PM2.5 that mean further model development would be required for the models to be deployed operationally.</p

Local and regional smoke impacts from prescribed fires

Smoke from wildfires poses a significant threat to affected communities. Prescribed burning is conducted to reduce the extent and potential damage of wildfires, but produces its own smoke threat. Planners of prescribed fires model the likely dispersion of smoke to help manage the impacts on local communities. Significant uncertainty remains about the actual smoke impact from prescribed fires, especially near the fire, and the accuracy of smoke dispersal models

A temporal framework of large wildfire suppression in practice, a qualitative descriptive study

Suppression activities on large wildfires are complicated. Existing suppression literature does not take into account this complexity which leaves existing suppression models and measures of resource productivity incomplete. A qualitative descriptive analysis was performed on the suppression activities described in operational documents of 10 large wildfires in Victoria, Australia. A five-stage classification system summarises suppression in the everyday terms ofwildfire management. Suppression can be heterogeneous across different sectors with different stages occurring across sectors on the same day. The stages and the underlying 20 suppression tasks identified provide a fundamental description of how suppression resources are being used on largewildfires. We estimate that at least 57% of resource use on our sample of 10 large wildfires falls outside of current suppression modelling and productivity research

Parents’ experiences of introducing toddlers to fruits and vegetables through repeated exposure, with and without prior visual familiarization to foods: evidence from daily diaries

While repeated exposure is an established method for inducing food acceptance in young children, little is known about parents’ experiences of repeatedly offering new or disliked foods at home. In this study, parents kept structured diary records during a 15-day period in which they offered their 2-year-old child daily tastes of one fruit and one vegetable. We explored how children’s acceptance of foods (measured in terms of willingness to taste, liking and intake) and the ease and enjoyment of the process for parents changed from the early (days 1-5) to middle (days 6-10) to later (days 11-15) phases of exposure. In addition, we explored whether prior visual familiarization to foods affected children’s behavior and/or parents’ experiences during exposure. Families were randomly assigned to look at a picture book about one to-be-exposed food for the two weeks prior to the exposure phase (‘fruit book’ and ‘vegetable book’ groups) or to a control group, who did not receive a book. Measures obtained from parents’ diary records revealed increases in willingness to taste and intake of vegetables and increased liking of both fruits and vegetables with greater exposure. Prior visual familiarization to vegetables further boosted children’s willingness to taste and liking of vegetables, and the ease and enjoyment of introducing these for parents. Children’s acceptance of foods and parents’ positivity during exposure predicted children’s liking and intake of foods 3 months later. Results confirm the potential for vegetable picture books to support parents in engaging with repeated exposure regimes and in successfully introducing vegetables into toddlers’ diets