Elena Moltchanova

Mapping global cropland and field size

A new 1 km global IIASA-IFPRI cropland percentage map for the baseline year 2005 has been developed which integrates a number of individual cropland maps at global to regional to national scales. The individual map products include existing global land cover maps such as GlobCover 2005 and MODIS v.5, regional maps such as AFRICOVER and national maps from mapping agencies and other organizations. The different products are ranked at the national level using crowdsourced data from Geo-Wiki to create a map that reflects the likelihood of cropland. Calibration with national and subnational crop statistics was then undertaken to distribute the cropland within each country and subnational unit. The new IIASA-IFPRI cropland product has been validated using very high-resolution satellite imagery via Geo-Wiki and has an overall accuracy of 82.4%. It has also been compared with the EarthStat cropland product and shows a lower root mean square error on an independent data set collected from Geo-Wiki. The first ever global field size map was produced at the same resolution as the IIASA-IFPRI cropland map based on interpolation of field size data collected via a Geo-Wiki crowdsourcing campaign. A validation exercise of the global field size map revealed satisfactory agreement with control data, particularly given the relatively modest size of the field size data set used to create the map. Both are critical inputs to global agricultural monitoring in the frame of GEOGLAM and will serve the global land modelling and integrated assessment community, in particular for improving land use models that require baseline cropland information. These products are freely available for downloading from the http://cropland.geo-wiki.org website.

Seasonal variation of diagnosis of Type 1 diabetes mellitus in children worldwide

Aims  To determine if there is a worldwide seasonal pattern in the clinical onset of Type 1 diabetes.

Comparing the similarity of responses received from studies in Amazon's Mechanical Turk to studies conducted online and with direct recruitment.

Computer and internet based questionnaires have become a standard tool in Human-Computer Interaction research and other related fields, such as psychology and sociology. Amazon’s Mechanical Turk (AMT) service is a new method of recruiting participants and conducting certain types of experiments. This study compares whether participants recruited through AMT give different responses than participants recruited through an online forum or recruited directly on a university campus. Moreover, we compare whether a study conducted within AMT results in different responses compared to a study for which participants are recruited through AMT but which is conducted using an external online questionnaire service. The results of this study show that there is a statistical difference between results obtained from participants recruited through AMT compared to the results from the participant recruited on campus or through online forums. We do, however, argue that this difference is so small that it has no practical consequence. There was no significant difference between running the study within AMT compared to running it with an online questionnaire service. There was no significant difference between results obtained directly from within AMT compared to results obtained in the campus and online forum condition. This may suggest that AMT is a viable and economical option for recruiting participants and for conducting studies as setting up and running a study with AMT generally requires less effort and time compared to other frequently used methods. We discuss our findings as well as limitations of using AMT for empirical studies.

Marked temporal increase in the incidence of type 1 and type 2 diabetes among young adults in Finland.

To the Editor: Previously we reported data on trends in the incidence of type 1 and type 2 diabetes in Finnish young adults aged 15–39 years during 1992–1996 [1] and found a 7.9% average annual increase in the incidence of type 2 diabetes. This rising trend needed to be confirmed during a longer period of follow-up, and therefore we extended the study until the year 2001. The collection of data and the classification of patients with diabetes ascertained during 1992 to 1996 have been described in detail previously [1]. The information on new diagnoses of diabetes in the age group of 15–39 years between 1997 and 2001 were obtained from three nationwide registers in Finland. The first register was the Drug Prescription Register of the Social Insurance Institute, which comprises ATC-DDD codes [2] on all prescriptions since 1994, and for this study all the class A10 drugs (drugs used in diabetes) were reviewed. The second register was the Drug Reimbursement Register of the Social Insurance Institute, which comprises information on persons entitled to free-of-charge medication for diabetes. The entitlement is given in response to an application that includes a detailed medical statement prepared by the treating physician. The third register was the Hospital Discharge Register, maintained by the National Research and Development Centre for Welfare and Health, which includes the treating physician’s diagnoses in ICD-10 codes [3]. Data from these registers were linked using the unique personal identification number assigned to every Finnish resident. The date of the first entry in any of these registers was set as the date of the diagnosis of diabetes. The patient had to be recorded in at least two of these registers to be included. A patient was classified as having type 1 diabetes if two of the following three criteria were fulfilled: (1) an ICD-10 diagnosis referring only to type 1 diabetes; (2) permanent entitlement to free-of-charge medication; (3) only insulin was administered immediately at diagnosis and continued until the end of the year 2004. A patient was classified as having type 2 diabetes if two of the following three criteria were fulfilled: (1) an ICD-10 diagnosis referring only to type 2 diabetes; (2) permanent or temporary entitlement to free-of-charge medication; (3) only oral glucose-lowering agents had been prescribed. For patients who could not be reliably classified with this method, the application records for free-of-charge medication were acquired from the Social Insurance Institute and reviewed in order to assign the type of diabetes (n=791). Information on patients with no entitlement to free-of-charge medication (n=563) was reviewed, and most were classified as having gestational diabetes, as expected (persons with gestational diabetes are not entitled to free-of-charge medication). Patients who were impossible to classify as having type 1 or type 2 diabetes were classified as having an undefined type of diabetes. Diabetologia (2008) 51:897–899 DOI 10.1007/s00125-008-0952-9

The incidence of type 1 diabetes among children in Finland--rural-urban difference.

The aim of the study was to investigate the incidence of type 1 diabetes among children aged 14 years or under according to the level of urbanization of the place of residence of children at the time of diagnosis in Finland during 1987 to 1996. The analysis was carried out using a Bayesian approach and GIS. The incidence was the highest in the rural heartland areas while the increase in incidence was sharpest in urban areas. The level of urbanization seems to explain only a part of the spatial variation in the incidence in Finland. It is possible that some environmental risk factors for type 1 diabetes have been more prevalent in rural heartland areas than in the rest of the country. These factors might have increased in urban environments in Finland particularly during the first half of 1990s.

Leukocyte telomere length and its relation to food and nutrient intake in an elderly population

Background/objectives:Shorter leukocyte telomere length (LTL) is associated with several chronic diseases, but only a few studies have assessed the association between dietary factors and LTL. Our objective was to study the association between fats, fruits, vegetables and LTL in a cross-sectional study design. We hypothesized that intakes of fruits and vegetables would be positively associated with LTL and that intakes of fats, and especially saturated fatty acids (SFAs), would be negatively associated with LTL.Subjects/methods:LTL was measured by quantitative real-time polymerase chain reaction in 1942 men and women aged 57–70 years from the Helsinki Birth Cohort Study. We assessed the whole diet by a validated semiquantitative 128-item food-frequency questionnaire.Results:In general, there were only a few significant results. However, total fat and SFA intake (P=0.04 and 0.01, respectively) were inversely associated with LTL in men adjusting for age and energy intake. In women, vegetable intake was positively associated with LTL (P=0.05). Men consuming the most butter and least fruits had significantly shorter telomeres than those consuming the lowest amounts of butter and highest amounts of fruits (P=0.05). We found no association between LTL and body mass index, waist–hip ratio, smoking, physical activity or educational attainment.Conclusions:In this cross-sectional study of elderly men and women, there were only a few statistically significant effects of diet, but in general they support the hypothesis that fat and vegetable intakes were associated with LTL.

Uncertainty in soil data can outweigh climate impact signals in global crop yield simulations.

Global gridded crop models (GGCMs) are increasingly used for agro-environmental assessments and estimates of climate change impacts on food production. Recently, the influence of climate data and weather variability on GGCM outcomes has come under detailed scrutiny, unlike the influence of soil data. Here we compare yield variability caused by the soil type selected for GGCM simulations to weather-induced yield variability. Without fertilizer application, soil-type-related yield variability generally outweighs the simulated inter-annual variability in yield due to weather. Increasing applications of fertilizer and irrigation reduce this variability until it is practically negligible. Importantly, estimated climate change effects on yield can be either negative or positive depending on the chosen soil type. Soils thus have the capacity to either buffer or amplify these impacts. Our findings call for improvements in soil data available for crop modelling and more explicit accounting for soil variability in GGCM simulations.

Calcium:Magnesium Ratio in Local Groundwater and Incidence of Acute Myocardial Infarction among Males in Rural Finland

Several epidemiologic studies have shown an association between calcium and magnesium and coronary heart disease mortality and morbidity. In this small-area study, we examined the relationship between acute myocardial infarction (AMI) risk and content of Ca, Mg, and chromium in local groundwater in Finnish rural areas using Bayesian modeling and geospatial data aggregated into 10 km × 10 km grid cells. Data on 14,495 men 35–74 years of age with their first AMI in the years 1983, 1988, or 1993 were pooled. Geochemical data consisted of 4,300 measurements of each element in local groundwater. The median concentrations of Mg, Ca, and Cr and the Ca:Mg ratio in well water were 2.61 mg/L, 12.23 mg/L, 0.27 μg/L, and 5.39, respectively. Each 1 mg/L increment in Mg level decreased the AMI risk by 4.9%, whereas a one unit increment in the Ca:Mg ratio increased the risk by 3.1%. Ca and Cr did not show any statistically significant effect on the incidence and spatial variation of AMI. Results of this study with specific Bayesian statistical analysis support earlier findings of a protective role of Mg and low Ca:Mg ratio against coronary heart disease but do not support the earlier hypothesis of a protective role of Ca.

Zinc and nitrate in the ground water and the incidence of Type 1 diabetes in Finland.

Aims  In Finland, the risk of childhood Type 1 diabetes varies geographically. Therefore we investigated the association between spatial variation of Type 1 diabetes and its putative environmental risk factors, zinc and nitrates.

Blunted hypothalamic-pituitary-adrenal axis and insulin response to psychosocial stress in young adults born preterm at very low birth weight

Young adults born preterm at very low birth weight (VLBW, ≤1500 g) have higher levels of cardiovascular risk factors, including impaired glucose regulation, than their term‐born peers. This could be mediated through altered hypothalamic‐pituitary‐adrenal axis (HPAA) response to stress.