Domesticated Asian rice (Oryza sativa) is one of the oldest domesticated crop species in the world, having fed more people than any other plant in human history. We report the patterns of DNA sequence variation in rice and its wild ancestor, O. rufipogon, across 111 randomly chosen gene fragments, and use these to infer the evolutionary dynamics that led to the origins of rice. There is a genome-wide excess of high-frequency derived single nucleotide polymorphisms (SNPs) in O. sativa varieties, a pattern that has not been reported for other crop species. We developed several alternative models to explain contemporary patterns of polymorphisms in rice, including a (i) selectively neutral population bottleneck model, (ii) bottleneck plus migration model, (iii) multiple selective sweeps model, and (iv) bottleneck plus selective sweeps model. We find that a simple bottleneck model, which has been the dominant demographic model for domesticated species, cannot explain the derived nucleotide polymorphism site frequency spectrum in rice. Instead, a bottleneck model that incorporates selective sweeps, or a more complex demographic model that includes subdivision and gene flow, are more plausible explanations for patterns of variation in domesticated rice varieties. If selective sweeps are indeed the explanation for the observed nucleotide data of domesticated rice, it suggests that strong selection can leave its imprint on genome-wide polymorphism patterns, contrary to expectations that selection results only in a local signature of variation.

Snow is a critically important and rapidly changing feature of the Arctic. However, snow-cover and snowpack conditions change through time pose challenges for measuring and prediction of snow. Plausible scenarios of how Arctic snow cover will respond to changing Arctic climate are important for impact assessments and adaptation strategies. Although much progress has been made in understanding and predicting snow-cover changes and their multiple consequences, many uncertainties remain. In this paper, we review advances in snow monitoring and modelling, and the impact of snow changes on ecosystems and society in Arctic regions. Interdisciplinary activities are required to resolve the current limitations on measuring and modelling snow characteristics through the cold season and at different spatial scales to assure human well-being, economic stability, and improve the ability to predict manage and adapt to natural hazards in the Arctic region.Electronic supplementary materialThe online version of this article (doi:10.1007/s13280-016-0770-0) contains supplementary material, which is available to authorized users.

SummaryObjective To measure the UK and Ireland incidence of childhood (<15 years) thyrotoxicosis and to describe the presenting features.Context Incidence data on thyrotoxicosis in childhood are not available for the UK and Ireland. Recent studies have reported an apparent increase in cases in Europe. Design A national prospective surveillance study for 12 months from September 2004, co-ordinated by The British Paediatric Surveillance Unit (BPSU). Patients and measurements All paediatricians across the UK and Ireland were requested monthly to report new cases. Details of presenting features were then obtained by questionnaire. Results One hundred ten cases of acquired childhood thyrotoxicosis were identified in the UK and Ireland. The incidence of acquired thyrotoxicosis was 0AE9 per 100,000 <15 years olds in the UK and Ireland, (95% CI: 0AE8-1AE1). Autoimmune thyrotoxicosis accounted for 96% of cases. There was an increasing incidence with age in each sex. Females have a significantly higher incidence than males in the 10-to 14-year age group. A variety of presenting symptoms were reported: weight loss (64%), fatigue/tiredness (54%), change in behaviour' (50%) and heat intolerance (47%). 4.5 % cases were asymptomatic. The commonest signs were goitre (78%) and tremor (58%). There were no cases of thyroid storm. Conclusions This national population survey defines the incidence of thyrotoxicosis in children in the UK and Ireland during 2004-2005, which was lower than expected in comparison with other European studies. The survey illustrates contemporary presenting characteristics of the disease.

Objective To assess the efficacy of annual CA125 and transvaginal ultrasound (TVU) scan as surveillance for ovarian cancer.Design Retrospective audit.Setting NHS Trust.Population Three hundred and forty-one asymptomatic women enrolled for ovarian cancer screening: 179 were in a high-risk group (>10% lifetime risk of developing ovarian cancer), 77 in a moderate risk group (4-10% lifetime risk of developing ovarian cancer) and 71 in a near population risk group (<4% lifetime risk).Methods Retrospective audit of case records, laboratory CA125 results, radiology reports, histology records and local cancer registry data.Main outcome measures Ovarian cancers occurring in study population. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of TVU, and CA125 as a screening tool for ovarian cancer.Results Four ovarian cancers and one endometrial cancer occurred. One ovarian cancer was detected at surveillance, three occurred in women who presented symptomatically between screenings. Thirty women underwent exploratory surgery because of abnormal findings at surveillance. Two women had cancer (PPV = 6.7%); one had ovarian cancer and the other endometrial cancer. Twenty-eight women (93.3%) had no malignancy. Sensitivity, specificity, PPV and NPV for TVU in the whole cohort were 33.3, 85.8, 0.6 and 99.8%, respectively. For high-risk individuals, the figures for TVU were 33.3, 84.5, 1.1 and 99.6, respectively. Combining both modalities for the whole cohort, the sensitivity, specificity, PPV and NPV were 66.7, 82.9, 1.5 and 99.8% and 50.0, 82.8, 1.3 and 99.7%, respectively, for the high-risk group alone.Conclusions Ovarian screening by annual TVU and CA125 is inefficient at detecting early-stage ovarian cancers.

Recent observations suggest that while some arctic landscapes are undergoing rapid change, others are apparently more resilient. In this study, we related surface cover and energy balance to microtopography in a degraded polygonal peat plateau (baydjarakh field) near Churchill, Manitoba in mid-summer 2010. The landscape consists of remnant high-centered polygons divided by troughs of varying widths. Historical aerial photos indicate these topographical features have been stable for over 80 years. Our goal was to explore patterns that might explain the apparent stability of this landscape over this time period and to evaluate remote sensing methods for characterizing microtopographic patterns that might resist change in the face of climate warming. Summertime surface albedo measurements were combined with several years of winter snow depth, snow heat flux, summer thaw depth and annual surface temperature, all of which had striking contrasts between wet troughs and high polygon centers. Measurements of albedo and the snowpack heat transfer coefficient were lowest for wet troughs (areas of standing water) dominated by graminoids, and were significantly higher for high polygon centers, dominated by dwarf shrubs and lichens. Snow depth, surface temperature and thaw depth were all significantly higher for wet troughs than high polygon centers. Together these patterns of cover and energy balance associated with microtopographic variation can contribute to the stability of this landscape through differential heat transfer and storage. We hypothesize that local thermal feedback effects, involving greater heat trapping in the troughs than on the baydjarakh tops, and effective insulation on the baydjarakh edges, have ensured landscape stability over most of the past century. These results suggest that high-resolution remote sensing, combined with detailed field monitoring, could provide insights into the dynamics or stability of arctic landscapes, where cover often varies over short distances due to microtopographic effects.