Using alterative whole-farm modelling approaches to assess farm enterprise selection, risk and welfare

Using an expected mean-variance model the changes in farm enterprise levels and indirect utility were examined under conditions of risk aversion, budget constraints and gross margin variance. An extension of the comparative statics of the expected mean-variance model was adopted by introducing a budget constraint into the constrained optimisation problem. A 10-year expected mean-variance whole-farm model was solved for a farm in the wheat-sheep zone of Australia to provide an empirical example. Results were obtained using no planning horizon (the static model) and then with a five-year rolling planning horizon (the dynamic model). In addition, enterprise levels were constrained to match levels observed on the farm so as to compare incomes between the constrained and unconstrained models. For a cash constrained, risk averse, farmer it was found that they are likely to have larger expenditures than less risk averse operators in order to obtain the same indirect utility. Enterprise levels differed between the dynamic and static models, and a dynamic model was used to help explain inter-temporal decision-making. Risk aversion reduced the set of possible welfare improving production activities available to a farmer.Whole-farm modelling, enterprise selection, risk., Farm Management, Q12, C61,

Learning Together 1: an educational model for training GPs, paediatricians: initial findings.

Learning Together is primarily an educational intervention, where paediatric registrars [SpRs] and General Practice (GP) registrars [GPSTs] see children together in a primary care setting. Over a six month period in 2013/2014, 44 learning pairs were set up mainly in North East and Central London. Proof of concept for the model at scale was achieved. Reported learning demonstrated: clinical learning themes of new knowledge, skill and communication skills; and collaborative themes of ongoing collaboration, satisfaction with team working and change in attitudes. These themes were identified in both sets of trainees. The self-reported learning is backed up by the results of a retrospective notes review of four common conditions based on NICE guidelines; constipation, asthma, feverish illness and eczema (CAFE). Guidance adherence improved from 57% before the intervention in solo GP training consultations to 72% during the joint clinic intervention (p < 0.01). After the intervention when the GP registrars returned to normal consultations, guidance adherence was 77% compared to before the intervention (p < 0.01). In addition 99% of the parents, who handed in feedback forms or took part in interviews, reported a good experience of care, and 87% reported increased confidence to manage their children's health following the consultation. A second, linked article examines the cost utility of Learning Together in its South London extension

The conundrum of stock versus bond prices

In a general way, stock and bond prices do not display any significant correlation. Yet, if we concentrate our attention on specific episodes marked by a crash followed by a rebound, then we observe that stock prices have a strong connection with interest rates on the one hand, and with bond yield spreads on the other hand. That second relationship is particularly stable in the course of time having been observed for over 140 years. Throughout the paper we use a quasi-experimental approach. By observing how markets respond to well-defined exogenous shocks (such as the shock of September 11, 2001) we are able to determine how investors organize their ``flight to safety'': which safe haven they select, how long their collective panic lasts, and so on. As rebounds come to an end the correlation of stock and bond prices fades away, a clear sign that the collective behavior of investors loses some of its coherence; this observation can be used as an objective criterion for assessing the end of a market rebound. Based on the behavior of investors, we introduce a distinction between ``genuine stock market rallies'', as opposed to spurious rallies such as those brought about by the buyback programs implemented by large companies. The paper ends with a discussion of testable predictions.Comment: 19 pages, 8 figures, 3 tables. To appear in "Physica A

Viscosity of cohesive granular flows.

Cohesive granular materials such as wet sand, snow, and powders can flow like a viscous liquid. However, the elementary mechanisms of momentum transport in such athermal particulate fluids are elusive. As a result, existing models for cohesive granular viscosity remain phenomenological and debated. Here we use discrete element simulations of plane shear flows to measure the viscosity of cohesive granular materials, while tuning the intensity of inter-particle adhesion. We establish that two adhesion-related, dimensionless numbers control their viscosity. These numbers compare the force and energy required to break a bond to the characteristic stress and kinetic energy in the flow. This progresses the commonly accepted view that only one dimensionless number could control the effect of adhesion. The resulting scaling law captures strong, non-Newtonian variations in viscosity, unifying several existing viscosity models. We then directly link these variations in viscosity to adhesion-induced modifications in the flow micro-structure and contact network. This analysis reveals the existence of two modes of momentum transport, involving either grain micro-acceleration or balanced contact forces, and shows that adhesion only affects the latter. This advances our understanding of rheological models for granular materials and other soft materials such as emulsions and suspensions, which may also involve inter-particle adhesive forces

Does authentic self-esteem buffer the negative effects of bullying victimization on social anxiety and classroom concentration? Evidence from a short-term longitudinal study with early adolescents

Background Bullying victimization is a risk factor for social anxiety and disrupted classroom concentration among young people. Self-esteem has been implicated as a protective factor, but extant literature is sparse. Aims Aim of present study was to test if a new measure of authentic self-esteem can buffer the negative effects of bullying victimization on social anxiety and disrupted classroom concentration concurrently and across time. Sample A short-term longitudinal questionnaire design was employed with 836 12- and 13-year-olds. Methods Peer nominations of bullying victimization and self-reports of authentic self-esteem were collected during winter term, and self-reports of social anxiety and disrupted classroom concentration were solicited then and also 5 months later. Results Hierarchical multiple regression models indicated that authentic self-esteem moderated the association between bullying victimization and (i) social anxiety both concurrently and longitudinally and (ii) disrupted classroom concentration longitudinally. The Johnson-Neyman technique identified where on its scale authentic self-esteem had its buffering effects, and these were found to be at relatively low or moderate levels. Conclusions Even moderate levels of authentic self-esteem can mitigate the association between being bullied and (i) social anxiety and (ii) disrupted classroom concentration. Efforts to monitor and where necessary enhance the authentic self-esteem of young people are warranted

Parenting about challenges and adolescents' social anxiety, disrupted classroom concentration and resilience knowledge: the mediating role of authentic self-esteem

A large theoretical and empirical literature indicates that parenting practices affect young people’s well-being and resilience, but there is much still to learn about psychological mechanisms, especially beyond infancy/early childhood. A recent model of authentic self-esteem argues that it arises out of experiences of challenge situations shared with parents and that it can subsequently act as a protective factor that supports well-being and resilience among young people. The aim of the current study is to test: (i) if parenting about challenges can predict three indices of adolescents’ well-being, namely their (a) social anxiety, (b) disrupted classroom concentration, and (c) ability to spontaneously generate resilient strategies, and more substantially (ii) if authentic self-esteem can mediate those associations if found. Adolescents (N = 836) completed a questionnaire that measured all of the study variables via self-report with the exception that unprompted open questions were used to gauge their ability to spontaneously generate resilient strategies. Parental discussions of challenges did significantly predict all three well-being indices, and authentic self-esteem was found to mediate all of these relationships. These results support the view that parenting about challenges is a practice that supports well-being and resilience in adolescents. It appears to do so through promoting the development of authentic self-esteem, a capacity to evaluate the self in a positive manner in the context of challenges. The theoretical and practical significance of these findings are discussed

Interdisciplinary approach to the demography of Jamaica

&lt;p&gt;Background: The trans-Atlantic slave trade dramatically changed the demographic makeup of the New World, with varying regions of the African coast exploited differently over roughly a 400 year period. When compared to the discrete mitochondrial haplotype distribution of historically appropriate source populations, the unique distribution within a specific source population can prove insightful in estimating the contribution of each population. Here, we analyzed the first hypervariable region of mitochondrial DNA in a sample from the Caribbean island of Jamaica and compared it to aggregated populations in Africa divided according to historiographically defined segments of the continent's coastline. The results from these admixture procedures were then compared to the wealth of historic knowledge surrounding the disembarkation of Africans on the island.&lt;/p&gt; &lt;p&gt;Results: In line with previous findings, the matriline of Jamaica is almost entirely of West African descent. Results from the admixture analyses suggest modern Jamaicans share a closer affinity with groups from the Gold Coast and Bight of Benin despite high mortality, low fecundity, and waning regional importation. The slaves from the Bight of Biafra and West-central Africa were imported in great numbers; however, the results suggest a deficit in expected maternal contribution from those regions.&lt;/p&gt; &lt;p&gt;Conclusions: When considering the demographic pressures imposed by chattel slavery on Jamaica during the slave era, the results seem incongruous. Ethnolinguistic and ethnographic evidence, however, may explain the apparent non-random levels of genetic perseverance. The application of genetics may prove useful in answering difficult demographic questions left by historically voiceless groups.&lt;/p&gt