Dynamical Belyi maps

We study the dynamical properties of a large class of rational maps with exactly three ramification points. By constructing families of such maps, we obtain infinitely many conservative maps of degree $d$; this answers a question of Silverman. Rather precise results on the reduction of these maps yield strong information on the rational dynamics.Comment: 21 page

Social Complexity and Nesting Habits Are Factors in the Evolution of Antimicrobial Defences in Wasps

Microbial diseases are important selective agents in social insects and one major defense mechanism is the secretion of cuticular antimicrobial compounds. We hypothesized that given differences in group size, social complexity, and nest type the secretions of these antimicrobials will be under different selective pressures. To test this we extracted secretions from nine wasp species of varying social complexity and nesting habits and assayed their antimicrobial compounds against cultures of Staphylococcus aureus. These data were then combined with phylogenetic data to provide an evolutionary context. Social species showed significantly higher (18x) antimicrobial activity than solitary species and species with paper nests showed significantly higher (11x) antimicrobial activity than those which excavated burrows. Mud-nest species showed no antimicrobial activity. Solitary, burrow-provisioning wasps diverged at more basal nodes of the phylogenetic trees, while social wasps diverged from the most recent nodes. These data suggest that antimicrobial defences may have evolved in response to ground-dwelling pathogens but the most important variable leading to increased antimicrobial strength was increase in group size and social complexity

Signal transduction in a covalent post-assembly modification cascade

Natural reaction cascades control the movement of biomolecules between cellular compartments. Inspired by these systems, we report a synthetic reaction cascade employing post-assembly modification reactions to direct the partitioning of supramolecular complexes between phases. The system is composed of a self-assembled tetrazine-edged FeII8L12 cube and a maleimide-functionalized FeII4L6 tetrahedron. Norbornadiene (NBD) functions as the stimulus that triggers the cascade, beginning with the inverse-electron-demand Diels–Alder reaction of NBD with the tetrazine moieties of the cube. This reaction generates cyclopentadiene as a transient by-product, acting as a relay signal that subsequently undergoes a Diels–Alder reaction with the maleimide-functionalized tetrahedron. Cyclooctyne can selectively inhibit the cascade by outcompeting NBD as the initial trigger. Initiating the cascade with 2-octadecyl NBD leads to selective alkylation of the tetrahedron upon cascade completion. The increased lipophilicity of the C18-tagged tetrahedron drives this complex into a non-polar phase, allowing its isolation from the initially inseparable mixture of complexes

Measures of low food variety and poor dietary quality in a cross-sectional study of London school children.

BACKGROUND/OBJECTIVES: The use of simple screening tools to measure nutritional adequacy in a public health context in developed countries are currently lacking. We explore the relationship between food variety and nutrient intake of London school children using a simple tool with potential use for screening for inadequate diets. SUBJECTS/METHODS: A cross-sectional survey was carried out in 2010. The survey included 2579 children aged 7-10 years in 52 primary schools in East London in the United Kingdom. The analysis included 2392 children (93% of the original sample). Food variety was assessed as the total number of listed foods recorded over 24 h using the validated Child and Diet Assessment Tool (CADET) comprising 115 listed foods divided into 16 food categories. Dietary quality was determined by the proportion of children meeting recommended intakes of individual micronutrients, namely, calcium, iron, zinc, folate, vitamin A and vitamin C. RESULTS: The mean number of CADET-listed foods consumed daily by children was 17.1 (95% CI: 16.8, 17.5). Children who consumed fewer than 11 foods on the collection day had particularly low nutrient intakes. Children consuming three different vegetables and two different fruits on average consumed 19-20 listed foods. It was estimated between 4 and 20% of children did not meet the recommended levels for individual micronutrients during the period of data collection. CONCLUSIONS: A simple method using food counts to assess daily food variety may help public health nutritionists identify groups of children at risk of inadequate diets

The Antiquity and Evolutionary History of Social Behavior in Bees

A long-standing controversy in bee social evolution concerns whether highly eusocial behavior has evolved once or twice within the corbiculate Apidae. Corbiculate bees include the highly eusocial honey bees and stingless bees, the primitively eusocial bumble bees, and the predominantly solitary or communal orchid bees. Here we use a model-based approach to reconstruct the evolutionary history of eusociality and date the antiquity of eusocial behavior in apid bees, using a recent molecular phylogeny of the Apidae. We conclude that eusociality evolved once in the common ancestor of the corbiculate Apidae, advanced eusociality evolved independently in the honey and stingless bees, and that eusociality was lost in the orchid bees. Fossil-calibrated divergence time estimates reveal that eusociality first evolved at least 87 Mya (78 to 95 Mya) in the corbiculates, much earlier than in other groups of bees with less complex social behavior. These results provide a robust new evolutionary framework for studies of the organization and genetic basis of social behavior in honey bees and their relatives

Association of food security status with overweight and dietary intake: exploration of White British and Pakistani-origin families in the Born in Bradford cohort.

BACKGROUND: Food insecurity has been associated with dietary intake and weight status in UK adults and children although results have been mixed and ethnicity has not been explored. We aimed to compare prevalence and trajectories of weight and dietary intakes among food secure and insecure White British and Pakistani-origin families. METHODS: At 12 months postpartum, mothers in the Born in Bradford cohort completed a questionnaire on food security status and a food frequency questionnaire (FFQ) assessing their child's intake in the previous month; at 18 months postpartum, mothers completed a short-form FFQ assessing dietary intake in the previous 12 months. Weights and heights of mothers and infants were assessed at 12-, 24-, and 36-months postpartum, with an additional measurement of children taken at 4-5 years. Associations between food security status and dietary intakes were assessed using Wilcoxon-Mann-Whitney for continuous variables and χ2 or Fisher's exact tests for categorical variables. Quantile and logistic regression were used to determine dietary intakes adjusting for mother's age. Linear mixed effects models were used to assess longitudinal changes in body mass index (BMI) in mothers and BMI z-scores in children. RESULTS: At 12 months postpartum, White British mothers reported more food insecurity than Pakistani-origin mothers (11% vs 7%; p < 0.01) and more food insecure mothers were overweight. Between 12 and 36 months postpartum, BMI increased more among food insecure Pakistani-origin mothers (β = 0.77 units, [95% Confidence Interval [CI]: 0.40, 1.10]) than food secure (β = 0.44 units, 95% CI: 0.33, 0.55). This was also found in Pakistani-origin children (BMI z-score: food insecure β = 0.40 units, 95% CI: 0.22, 0.59; food secure β = 0.25 units, 95% CI: 0.20, 0.29). No significant increases in BMI were observed for food secure or insecure White British mothers while BMI z-score increased by 0.17 (95% CI: 0.13, 0.21) for food secure White British children. Food insecure mothers and children had dietary intakes of poorer quality, with fewer vegetables and higher consumption of sugar-sweetened drinks. CONCLUSIONS: Food security status is associated with body weight and dietary intakes differentially by ethnicity. These are important considerations for developing targeted interventions

Occupation of racial grief, loss as a resource : learning from ‘The Combahee River Collective Black Feminist Statement'

The methodology of ‘occupation’ through rereading The Combahee River Collective Black Feminist Statement (The Combahee River Collective, in: James, Sharpley-Whiting (eds) The Black Feminist Reader. Blackwell Publishers Ltd., Oxford, pp 261–270, 1977) demonstrates the necessity of temporal linkages to historical Black feminist texts and the wisdom of Black feminist situated knowers. This paper argues that racism produces grief and loss and as long as there is racism, we all remain in racial grief and loss. However, in stark contrast to the configuration of racial grief and loss as something to get over, perhaps grief and loss can be thought about differently, for example, in terms of racial grief and loss as a resource. This paper questions Western Eurocentric paternalistic responses to Black women’s ‘talk about their feelings of craziness… [under] patriarchal rule’ (The Combahee River Collective 1977: 262) and suggests alternative ways of thinking about the psychological impact of grief and loss in the context of racism. In this paper, a Black feminist occupation of racial grief and loss includes the act of residing within, and the act of working with the constituent elements of racial grief and loss. The proposal is that an occupation of racial grief and loss is a paradoxical catalyst for building a twenty-first century global intersectional Black feminist movement

Prescribing indicators at primary health care centers within the WHO African region: a systematic analysis (1995-2015)

Abstract Background Rational medicine use is essential to optimize quality of healthcare delivery and resource utilization. We aim to conduct a systematic review of changes in prescribing patterns in the WHO African region and comparison with WHO indicators in two time periods 1995–2005 and 2006–2015. Methods Systematic searches were conducted in PubMed, Scopus, Web of science, Africa-Wide Nipad, Africa Journals Online (AJOL), Google scholar and International Network for Rational Use of Drugs (INRUD) Bibliography databases to identify primary studies reporting prescribing indicators at primary healthcare centres (PHCs) in Africa. This was supplemented by a manual search of retrieved references. We assessed the quality of studies using a 14-point scoring system modified from the Downs and Black checklist with inclusions of recommendations in the WHO guidelines. Results Forty-three studies conducted in 11 African countries were included in the overall analysis. These studies presented prescribing indicators based on a total 141,323 patient encounters across 572 primary care facilities. The results of prescribing indicators were determined as follows; average number of medicines prescribed per patient encounter = 3.1 (IQR 2.3–4.8), percentage of medicines prescribed by generic name =68.0 % (IQR 55.4–80.3), Percentage of encounters with antibiotic prescribed =46.8 % (IQR 33.7–62.8), percentage of encounters with injection prescribed =25.0 % (IQR 18.7–39.5) and the percentage of medicines prescribed from essential medicines list =88.0 % (IQR 76.3–94.1). Prescribing indicators were generally worse in private compared with public facilities. Analysis of prescribing across two time points 1995–2005 and 2006–2015 showed no consistent trends. Conclusions Prescribing indicators for the African region deviate significantly from the WHO reference targets. Increased collaborative efforts are urgently needed to improve medicine prescribing practices in Africa with the aim of enhancing the optimal utilization of scarce resources and averting negative health consequences