University of Iceland

About: University of Iceland is a education organization based out in Reykjavik, Suðurnes, Iceland. It is known for research contribution in the topics: Population & Genome-wide association study. The organization has 5423 authors who have published 16199 publications receiving 694762 citations. The organization is also known as: Háskóli Íslands.

The origin of Arctic precipitation under present and glacial conditions

Abstract: At low altitude locations, the deuterium excess d = δ D - 8δ 18 O in precipitation generally varies with the season in antiphase with the δ's. In the high-altitude regions of the Greenland ice sheet, however, d in the snow varies with only a few months time lag behind the δ's. A model for d values in Greenland precipitation is developed on the basis of Rayleigh condensation/sublimation with due account taken of kinetic effects during both evaporation of sea water and sublimation. The model predicts that the initial mixing ratio w so in precipitating air determines the slope of the d versus δ relationship at late stages of the precipitation process, and that the sea surface temperature T s in the source area of the moisture only influences the d level. The generally high d -values in ice sheet precipitation are compatible only with high values of W so and T s , which suggests the subtropical part of the North Atlantic Ocean as a dominating moisture source for ice sheet precipitation. This is supported experimentally: when the model is run with monthly W so and T s mean values oberved at Ship E (35° N, 48° W), it reproduces the high d level, the amplitude of the seasonal d variations, and the few months phase difference between d and δ on the ice sheet. None of these features can be reproduced with a local, high-latitude moisture source. Detailed isotope analyses of ice core increments, spanning several abrupt climatic shifts under glacial conditions, show close to present d values during the cold phases, but lower d values during the mild phases. This feature is discussed in the light of the model experiments. DOI: 10.1111/j.1600-0889.1989.tb00321.x

Physical fitness, injuries, and team performance in soccer.

Abstract: ARNASON, A., S. B. SIGURDSSON, A. GUDMUNDSSON, I. HOLME, L. ENGEBRETSEN, and R. BAHR. Physical Fitness, Injuries, and Team Performance in Soccer. Med. Sci. Sports Exerc., Vol. 36, No. 2, pp. 278 –285, 2004. Purpose: To investigate the relationship between physical fitness and team success in soccer, and to test for differences in physical fitness between different player positions. Methods: Participants were 306 male soccer players from 17 teams in the two highest divisions in Iceland. Just before the start of the 1999 soccer season, the following variables were tested: height and weight, body composition, flexibility, leg extension power, jump height, and peak O2 uptake. Injuries and player participation in matches and training were recorded through the 4-month competitive season. Team average physical fitness was compared with team success (final league standing) using a linear regression model. Physical fitness was also compared between players in different playing positions. Results: A significant relationship was found between team average jump height (countermovement jump and standing jump) and team success (P 0.009 and P 0.012, respectively). The same trend was also found for leg extension power (P 0.097), body composition (% body fat, P 0.07), and the total number of injury days per team (P 0.09). Goalkeepers demonstrated different fitness characteristics from outfield players. They were taller and heavier, more flexible in hip extension and knee flexion, and had higher leg extension power and a lower peak O2 uptake. However, only minor differences were observed between defenders, midfield players, and attackers. Conclusion: Coaches and medical support teams should pay more attention to jump and power training, as well as preventive measures and adequate rehabilitation of previous injuries to increase team success. Key Words: PHYSICAL PERFORMANCE, MAXIMAL O 2 UPTAKE, JUMPING ABILITY, LEG POWER, FLEXIBILITY, BODY COMPOSITION

Development: Time to leave GDP behind

Abstract: Gross domestic product is a misleading measure of national success. Countries should act now to embrace new metrics, urge Robert Costanza and colleagues.

Parent-of-origin-specific allelic associations among 106 genomic loci for age at menarche

Abstract: Age at menarche is a marker of timing of puberty in females. It varies widely between individuals, is a heritable trait and is associated with risks for obesity, type 2 diabetes, cardiovascular disease, breast cancer and all-cause mortality. Studies of rare human disorders of puberty and animal models point to a complex hypothalamic-pituitary-hormonal regulation, but the mechanisms that determine pubertal timing and underlie its links to disease risk remain unclear. Here, using genome-wide and custom-genotyping arrays in up to 182,416 women of European descent from 57 studies, we found robust evidence (P < 5 × 10(-8)) for 123 signals at 106 genomic loci associated with age at menarche. Many loci were associated with other pubertal traits in both sexes, and there was substantial overlap with genes implicated in body mass index and various diseases, including rare disorders of puberty. Menarche signals were enriched in imprinted regions, with three loci (DLK1-WDR25, MKRN3-MAGEL2 and KCNK9) demonstrating parent-of-origin-specific associations concordant with known parental expression patterns. Pathway analyses implicated nuclear hormone receptors, particularly retinoic acid and γ-aminobutyric acid-B2 receptor signalling, among novel mechanisms that regulate pubertal timing in humans. Our findings suggest a genetic architecture involving at least hundreds of common variants in the coordinated timing of the pubertal transition.

Refining the impact of TCF7L2 gene variants on type 2 diabetes and adaptive evolution

Abstract: We recently described an association between risk of type 2diabetes and variants in the transcription factor 7-like 2 gene (TCF7L2; formerly TCF4), with a population attributable risk (PAR) of 17%-28% in three populations of European ancestry. Here, we refine the definition of the TCF7L2 type 2diabetes risk variant, HapB(T2D), to the ancestral T allele of a SNP, rs7903146, through replication in West African and Danish type 2 diabetes case-control studies and an expanded Icelandic study. We also identify another variant of the same gene, HapA, that shows evidence of positive selection in East Asian, European and West African populations. Notably, HapA shows a suggestive association with body mass index and altered concentrations of the hunger-satiety hormones ghrelin and leptin in males, indicating that the selective advantage of HapA may have been mediated through effects on energy metabolism.