University of Copenhagen

About: University of Copenhagen is a education organization based out in Copenhagen, Denmark. It is known for research contribution in the topics: Population & Galaxy. The organization has 57645 authors who have published 149740 publications receiving 5903093 citations. The organization is also known as: Copenhagen University & Københavns Universitet.

Introduction to topological superconductivity and Majorana fermions

Abstract: This short review paper provides a pedagogical introduction to the rapidly growing research field of Majorana fermions in topological superconductors. We first discuss in some detail the simplest ‘toy model’ in which Majoranas appear, namely a one-dimensional tight-binding representation of a p-wave superconductor, introduced more than 10 years ago by Kitaev. We then give a general introduction to the remarkable properties of Majorana fermions in condensed matter systems, such as their intrinsically non-local nature and exotic exchange statistics, and explain why these quasiparticles are suspected to be especially well suited for low-decoherence quantum information processing. We also discuss the experimentally promising (and perhaps already successfully realized) possibility of creating topological superconductors using semiconductors with strong spin–orbit coupling, proximity-coupled to standard s-wave superconductors and exposed to a magnetic field. The goal is to provide an introduction to the subject for experimentalists or theorists who are new to the field, focusing on the aspects which are most important for understanding the basic physics. The text should be accessible for readers with a basic understanding of quantum mechanics and second quantization, and does not require knowledge of quantum field theory or topological states of matter.

Potential of biobased materials for food packaging

Abstract: During the last decade, joint efforts by the packaging and the food industries have reduced the amount of food packaging materials. Nonetheless, used packaging materials are still very visible to the consumer in the context of disposal. Environmental issues are becoming increasingly important to the European consumer. Consequently, consumer pressure may trigger the use of biobased packaging materials as an alternative to materials produced from non-renewable resources. Biologically based packaging is defined as packaging containing raw materials originating from agricultural sources, i. e. produced from renewable, biological raw materials such as starch and bioderived monomers. These materials are not necessarily biodegradable. Consequently, this review is not limited to biodegradable packaging. To date, biodegradable packaging has commanded great attention, and numerous projects are under way in this field. One important reason for this attention is the marketing of environmentally friendly packaging materials. Furthermore, use of biodegradable packaging materials has the greatest potential in countries where landfill is the main waste management tool. Biobased packaging materials include both edible films and edible coatings along with primary and secondary packaging materials. Excellent in-depth reviews on edible films and coatings are already available 1 , 2 , 3 . Therefore, this review focuses on biobased primary packaging materials for foods. Several concerns must be addressed prior to commercial use of biobased primary food packaging materials. These concerns include degradation rates under various conditions, changes in mechanical properties during storage, potential for microbial growth, and release of harmful compounds into the packaged food product. Furthermore, the biopackaging must function as food packaging and meet the requirements of the individual food product. This review evaluates the suitability of biobased packaging for foods. Additionally, it identifies the challenges involved when using biobased packaging for different foods.

Oxidative DNA damage estimated by 8-hydroxydeoxyguanosine excretion in humans: influence of smoking, gender and body mass index.

Abstract: Oxidative DNA damage may be implicated in ageing, carcinogenesis and other degenerative diseases. Oxidative DNA damage can be assessed in humans in vivo from the urinary excretion of the DNA-repair product 8-hydroxydeoxyguanosine (8OHdG). We investigated factors influencing the excretion of 8OHdG in 24 h urine from 83 randomly selected healthy subjects (52 women) aged 40-64 years. For 2 weeks prior to urine collection the subjects kept a weighed diet record. 8OHdG was quantified by an automatic three-dimensional HPLC analysis with electrochemical detection. The 8OHdG excretion was 252 +/- 103 (mean +/- SD) pmol kg body weight/24 h with a range from 78 to 527. Multiple regression analysis identified three factors, smoking, body mass index (BMI) and gender, as significant predictors of the 8OHdG excretion. In 30 smokers the 8OHdG excretion was 320 +/- 99 pmol/kg/24 h opposed to 213 +/- 84 pmol/kg/24 h in 53 non-smokers. According to multiple regression analysis smokers excreted 50% (31-69%; 95% confidence interval) more 8OHdG than non-smokers. In 52 women the 8OHdG excretion was 240 +/- 106 pmol/kg/24 h opposed to 271 +/- 96 pmol/kg/24 h in 31 men. According to the multiple regression analysis men excreted 29% (10-48%) more 8OHdG than women. According to multiple regression analysis the 8OHdG excretion decreased with 4% (2-6%) per increment in BMI measured in kg/m2. The dietary distribution of energy demonstrated no important predictive value with respect to 8OHdG excretion. The intake of the antioxidant vitamins C and E and of vitamin A equivalents, including beta-carotene, was not associated with 8OHdG excretion. The results suggest that smoking increases oxidative DNA damage by approximately 50%. This effect implies potential serious health effects adding to the other well-known health hazards of smoking. The higher 8OHdG excretion in men and lean subjects may be related to a higher rate of metabolism with increased availability of reactive oxygen species. The apparent 7-fold individual variation in oxidative DNA damage carries implications regarding the rate of ageing and the risk of cancer and other degenerative diseases. The excretion of 8OHdG into urine offers a valuable tool for testing such hypotheses in humans.

Interleukin-6 receptor pathways in coronary heart disease: a collaborative meta-analysis of 82 studies

Abstract: Background Persistent inflammation has been proposed to contribute to various stages in the pathogenesis of cardiovascular disease. Interleukin-6 receptor (IL6R) signalling propagates downstream inflammation cascades. To assess whether this pathway is causally relevant to coronary heart disease, we studied a functional genetic variant known to affect IL6R signalling. Methods In a collaborative meta-analysis, we studied Asp358Ala (rs2228145) in IL6R in relation to a panel of conventional risk factors and inflammation biomarkers in 125 222 participants. We also compared the frequency of Asp358Ala in 51 441 patients with coronary heart disease and in 136 226 controls. To gain insight into possible mechanisms, we assessed Asp358Ala in relation to localised gene expression and to postlipopolysaccharide stimulation of interleukin 6. Findings The minor allele frequency of Asp358Ala was 39%. Asp358Ala was not associated with lipid concentrations, blood pressure, adiposity, dysglycaemia, or smoking (p value for association per minor allele >= 0.04 for each). By contrast, for every copy of 358Ala inherited, mean concentration of IL6R increased by 34.3% (95% CI 30.4-38.2) and of interleukin 6 by 14.6% (10.7-18.4), and mean concentration of C-reactive protein was reduced by 7.5% (5.9-9.1) and of fibrinogen by 1.0% (0.7-1.3). For every copy of 358Ala inherited, risk of coronary heart disease was reduced by 3.4% (1.8-5.0). Asp358Ala was not related to IL6R mRNA levels or interleukin-6 production in monocytes. Interpretation Large-scale human genetic and biomarker data are consistent with a causal association between IL6R-related pathways and coronary heart disease.