Detailed Structure and Dynamics in Particle-in-Cell Simulations of the Lunar Wake

The solar wind plasma from the Sun interacts with the Moon, generating a wake structure behind it, since the Moon is to a good approximation an insulator, has no intrinsic magnetic field and a very thin atmosphere. The lunar wake in simplified geometry has been simulated via a 1-1/2-D electromagnetic particle-in-cell code, with high resolution in order to resolve the full phase space dynamics of both electrons and ions. The simulation begins immediately downstream of the moon, before the solar wind has infilled the wake region, then evolves in the solar wind rest frame. An ambipolar electric field and a potential well are generated by the electrons, which subsequently create a counter-streaming beam distribution, causing a two-stream instability which confines the electrons. This also creates a number of electron phase space holes. Ion beams are accelerated into the wake by the ambipolar electric field, generating a two stream distribution with phase space mixing that is strongly influenced by the potentials created by the electron two-stream instability. The simulations compare favourably with WIND observations.Comment: 10 pages, 13 figures, to be published in Physics of Plasma

Austral summer droughts and their driving mechanisms in observations and present‐day climate simulations over Malawi

Droughts are a key feature of weather systems over Malawi and southern Africa. Their societal relevance in Malawi underscores the need for improved understanding of drought characteristics and atmospheric processes that drive them. We use the Standardized Precipitation and Evapotranspiration Index with the run theory to identify and characterize droughts in observations (1961–2017) and CMIP5 models across Malawi. We find no major differences in drought duration, severity, and intensity between the northern and southern parts of Malawi. However, circulation patterns associated with droughts in the two regions are different, and typically organized in such a way that droughts in one region coincide with wetter conditions in the other. Anomalous circulation patterns diminishing moisture convergence and convection over the affected region are a typical feature of summer droughts. We show that precipitation variability is principally governed by advected moisture, transported via three main tracks of northwesterly, northeasterly, and southeasterly moisture fluxes. The three tracks interact to form a convergence zone with a peak situated over Malawi. Variability in the respective moisture flux tracks influences the variability in the location and intensity of the convergence zone, and thus the location of the ensuing drought. We note links between variability in the moisture advection tracks and El Nino Southern Oscillations and other modes of variability including the Indian Ocean Dipole and Subtropical Indian Ocean Dipole. Both negative and positive biases in drought frequency are apparent in CMIP5 models but the majority overestimate drought duration and severity. The relationship between precipitation and net total moisture flux is consistently simulated. However, we note significant model inconsistencies in the relationship between precipitation and moisture flux from the southeasterly track, which potentially undermines the confidence in model simulation of drought processes over Malawi

Service brand rehab: Diagnosing trust repair mechanisms

This paper aims to understand consumers’ response to the trust repair mechanisms adopted by corporate brands in a service sector context following prominent trust damaging organizational transgressions. Adopting a qualitative approach, six focus group discussions are employed to investigate three high profile consumer trust erosion cases within the service sector. Consumer trust varies by context. Despite the severity of trust damage, corporate brands can recover trust towards their brands amongst consumers not directly affected by transgressions. Not all trust repair mechanisms are equally applicable to all service contexts and re-branding could be used as a trust repair mechanism. Corporate brands in the service sector should focus on sense-making, relational approaches and transparency. Orchestration of trust repair mechanisms needs to be integrated within the trust rehabilitation processes. This study illustrates it is important to reconsider trust repair processes to accommodate context and integrate post-transgression consumer research. Successful corporate brand rehabilitation of consumer trust requires examination of the trustworthiness dimensions consumers express before and after the transgression to select the most appropriate trust repair mechanisms. Findings suggest organizations also have preventative trust repair management programs. This research is the first to empirically apply the conceptual framework of Bachmann et al. (2015) to explore consumer responses to the trust repair mechanisms adopted by corporate brands by context

Impact of climate change on crop suitability in sub-Saharan Africa in parameterized and convection-permitting regional climate models

Due to high present-day temperatures and reliance on rainfed agriculture, sub-Saharan Africa is highly vulnerable to climate change. We use a comprehensive set of global (CMIP5) and regional (CORDEX-Africa) climate projections and a new convection-permitting pan-Africa simulation (and its parameterized counterpart) to examine changes in rainfall and temperature and the impact on crop suitability of maize, cassava and soybean in sub-Saharan Africa by 2100 (RCP8.5). This is the first time an explicit-convection simulation has been used to examine crop suitability in Africa. Increasing temperatures and declining rainfall led to large parts of sub-Saharan Africa becoming unsuitable for multiple staple crops, which may necessitate a transition to more heat and drought resistant crops to ensure food and nutrition security. Soybean was resilient to temperature increases, however maize and cassava were not, leading to declines in crop suitability. Inclusion of sensitivity to extreme temperatures led to larger declines in maize suitability than when this was excluded. The results were explored in detail for Tanzania, Malawi, Zambia and South Africa. In each country the range of projections included wetting and drying, but the majority of models projected rainfall declines leading to declines in crop suitability, except in Tanzania. Explicit-convection was associated with more high temperature extremes, but had little systematic impact on average temperature and total rainfall, and the resulting suitability analysis. Global model uncertainty, rather than convection parameterizations, still makes up the largest part of the uncertainty in future climate. Explicit-convection may have more impact if suitability included a more comprehensive treatment of extremes. This work highlights the key uncertainty from global climate projections for crop suitability projections, and the need for improved information on sensitivities of African crops to extremes, in order to give better predictions and make better use of the new generation of explicit-convection models

Children's acceptance of milk with xylitol or sorbitol for dental caries prevention

BACKGROUND: Xylitol, a polyol sugar, has been shown to reduce dental caries when mixed with food or chewing gum. This study examines the taste acceptability of xylitol in milk as a first step toward measuring the effectiveness of xylitol in milk for the reduction of dental caries in a public health program. METHODS: Three different types of milk (Ultra High Temperature (UHT), powder and evaporated) were tested for acceptability by 75 Peruvian children (25 per milk group, ages 4 to 7 years). Each group evaluated xylitol and sorbitol in one type of milk. In the first phase, each child was presented with a tray of four plastic cups containing 50 ml of milk with 0.021 g/ml xylitol, 0.042 g/ml xylitol, 0.042 g/ml sorbitol or no sugar. Each child was asked to taste the samples in a self-selected order. After tasting each sample, the child placed the milk cup in front of one of three cartoon faces (smile, frown or neutral) representing the child's response to the taste of each sample. In the second phase, the child was asked to rank order the milk samples within each category (smile, frown or neutral). Ranks within categories were then combined to obtain a rank ordering for all the test samples. RESULTS: The ranking from best to worst for the samples across categories (UHT, powder, evaporated) was xylitol (0.0.042 g/ml), sorbitol (0.042 g/ml), xylitol (0.021 g/ml) and milk alone (Friedman's ANOVA). Xylitol and sorbitol were preferred over milk alone, and xylitol (0.042 g/ml) was preferred to sorbitol (0.042 g/ml)(p < .05 sign test). CONCLUSION: Milk sweetened with xylitol is well accepted by Peruvian children ages 4–7 years

Unprecedented climate extremes in South Africa and implications for maize production

This is the final version. Available on open access from IOP Publishing via the DOI in this recordData availability statement: Any data that support the findings of this study are included within the article.Maize is the most important crop grown in South Africa, but yields can be severely reduced by extreme high summer average temperatures and low precipitation, potentially adversely affecting both domestic consumption and regional food security exports. To help understand and manage climate risks to food security in Southern Africa it is essential to quantify the present-day likelihood and magnitude of climate extremes in South Africa’s maize-growing region and explore the potential for unprecedented climate conditions which would likely result in record low maize yields. We analyse a large ensemble of initialised climate model simulations, which provides almost 100 times as many plausible present-day summers as the equivalent observational dataset. We quantify the risk of unprecedented climate extremes affecting maize production in South Africa and examine the role of the El Niño-Southern Oscillation. We find that the South African maize region is at risk of experiencing record-breaking hot, cold, dry or wet events under current climatic conditions. We find that the annual chance of unprecedented high temperatures in South Africa is approximately 4%, increasing to 62% during very strong El Niño years. We also find that the chance of exceeding the present day seasonal high temperature record has increased across the 1979-2018 period, being five times more likely now than it was in 1980. These extreme events could result in a record-breaking number of days above the optimum, or even the maximum, temperature for maize production, and lead to more severe floods or droughts. Under climate change scenarios, the magnitude and frequency of climate extremes is projected to increase meaning that the unprecedented extremes studied here could become commonplace in the future. This suggests that significant investment is needed to develop adaptations that manage the climate-related risks to food systems now and build resilience to the projected impacts of climate change.Biotechnology and Biological Sciences Research Council (BBSRC

Solar System Processes Underlying Planetary Formation, Geodynamics, and the Georeactor

Only three processes, operant during the formation of the Solar System, are responsible for the diversity of matter in the Solar System and are directly responsible for planetary internal-structures, including planetocentric nuclear fission reactors, and for dynamical processes, including and especially, geodynamics. These processes are: (i) Low-pressure, low-temperature condensation from solar matter in the remote reaches of the Solar System or in the interstellar medium; (ii) High-pressure, high-temperature condensation from solar matter associated with planetary-formation by raining out from the interiors of giant-gaseous protoplanets, and; (iii) Stripping of the primordial volatile components from the inner portion of the Solar System by super-intense solar wind associated with T-Tauri phase mass-ejections, presumably during the thermonuclear ignition of the Sun. As described herein, these processes lead logically, in a causally related manner, to a coherent vision of planetary formation with profound implications including, but not limited to, (a) Earth formation as a giant gaseous Jupiter-like planet with vast amounts of stored energy of protoplanetary compression in its rock-plus-alloy kernel; (b) Removal of approximately 300 Earth-masses of primordial gases from the Earth, which began Earth's decompression process, making available the stored energy of protoplanetary compression for driving geodynamic processes, which I have described by the new whole-Earth decompression dynamics and which is responsible for emplacing heat at the mantle-crust-interface at the base of the crust through the process I have described, called mantle decompression thermal-tsunami; and, (c)Uranium accumulations at the planetary centers capable of self-sustained nuclear fission chain reactions.Comment: Invited paper for the Special Issue of Earth, Moon and Planets entitled Neutrino Geophysics Added final corrections for publicatio

A conceptual classification of parents’ attributions of the role of food advertising in children’s diets

Background: High levels of child obesity are triggering growing concerns about the prevalence and effects of food advertising targeted at children. Efforts to address this advertising are confounded by the expanding repertoire of media and promotional techniques used to reach and attract children. The present study explored parents’ views on food marketing and the strategies parents employ when attempting to ameliorate its effects. As part of an online survey of Australian parents’ attitudes towards a range of food advertisements, respondents were invited to provide additional comment in an open-ended question. The question was optional and asked “Are there any other comments you would like to make?”. One in five of the survey respondents (18%; n = 235) elected to answer this question by discussing their views on food advertising and children’s diets. The responses were imported into NVivo10 for coding and analysis. A grounded approach was used to draw meaning from the data and develop a proposed conceptual classification of parents’ attributions relating to food advertising and its consequences.Results: The majority of responses related to the negative perceived effects of unhealthy food advertising on children’s diets, with few respondents considering such advertisements to be innocuous. The responses were classified into four conceptual categories reflecting differing attitudes to advertising (negative to neutral) and varying levels of locus of control (low to high). The typical characteristics of parents allocated to the four categories exhibited variation according to weight status, television viewing habits, education level, and family size. The largest number of responses was coded to the category characterized by a negative attitude toward food advertising and a low locus of control. Parents in this category were more likely than others to be overweight/obese and heavy television viewers. Parents in the negative attitude to advertising and high locus of control category nominated a variety of parenting practices that could form the basis of parent education interventions. Conclusions: The results suggest that many Australian parents may feel disempowered in the face of high levels of advertising for unhealthy foods. The current voluntary regulatory code appears to be inadequate in scope and coverage to address this situation

Estimating population size, density and dynamics of Pre-Pottery Neolithic villages in the central and southern Levant: an analysis of Beidha, southern Jordan

The Pre-Pottery Neolithic (PPN) of the central and southern Levant played an integral role in the Neolithic Demographic Transition (NDT) from mobile hunter-gatherer to village-based, agro-pastoralist societies. An understanding of population dynamics is essential for reconstructing the trajectories of these early village societies. However, few investigations have produced absolute estimates of population parameters for these villages and those which have base estimates on a limited methodological framework. This research examines the methodological and theoretical basis for existing estimates, and explores a range of methodologies in order to derive more empirically-robust demographic data. Results reveal that commonly utilized methodologies and population density coefficients employed for estimating PPN village populations require re-evaluation. This article presents the application of methodologies to the PPNB site of Beidha in southern Jordan