1,158 research outputs found
A Comparison of Naturally Enhanced Ion Acoustic Lines and Auroral Spectral Line Emissions
In this thesis, we present Naturally Enhanced Ion Acoustic Lines (NEIALs) observed with the EISCAT Svalbard Radar and a comparison with auroral emissions lines measured with a Meridian Scanning Photometer. NEIALs are short-lived events noticeable in the incoherent scatter spectra as an enhancement in one or both shoulders.
It has been assumed that NEIALs are associated with an active red emission line in the aurora with an intensity above 10 kR. The red emission line intensity is associated with soft particle precipitation. However, NEIALs have also been observed at low altitudes where particles with higher energies are present, and they are also associated with a severe geomagnetic activity (>500 nT).
In the literature, there are three competing theories which might explain the cause of NEIALs in the ionosphere, and they all require free energy provided by auroral particle precipitation. The theories are associated with partly different energy ranges, and auroral emission lines may give an indication of the energies of the precipitating particles.
We analyzed four separate days where there were NEIAL incidents. For most of the events, the red line intensity was greater than 10 kR. This agrees with previous observations, and it supports the parametric decay of Langmuir wave theory, which requires soft particles precipitation. However, we have identified 7 events where the red line intensities were below 10 kR, and this weakens the requirement of 10 kR for NEIALs to appear.
When NEIALs were observed at lower altitudes (<400 km), the intensity of the green line increased and the right shoulder in the spectra was the most enhanced. This could suggest that at these altitudes, the current driven instability might be the prevailing theory for the production of NEIALs.
We also found that increased power in the incoherent scatter spectra might be associated with enhancements in the red line intensity.
NEIALs were also observed when the geomagnetic activity was below 500 nT
Design and pilot testing of a dietary assessment methodology for children at school
Nutrition's impact on an individual's health and sustainable consumption of food are issues that have long been on both the public and political agenda but are often viewed as two separate debates. This is surprising since many innovation projects in food service systems are concerned with both healthy eating and sustainable consumption (organic food). The relationship between them forms the background in this study. Evidence has shown that caterers serving organic food tend to also serve healthier meals than their non-organic counterparts but, so far, no studies have been carried out in school food environments.
The aim of this report was to investigate and develop appropriate methods for studying the link between healthy eating practices and organic food procurement policies using Danish public elementary schools as a setting.
Based on relevant scientific literature, the Danish Dietary Recommendations, and inspired by other successful studies, a self-administered questionnaire investigating children‟s eating habits was designed. After testing by an Expert Evaluation Panel and Think Aloud Interviews adjustments were integrated.
Conclusion: If special attention is given to literacy skills and cognitive development, children in Danish 6th grade classes can be used as respondents in studies of the relation between food procurement policies and eating practice
Polymorphisms in Nucleotide Excision Repair Genes and Risk of Colorectal Cancer: A Systematic Review
Exploring the unintended consequences of managerial ‘paradox sharing’ with subordinates and superiors. The case of the Royal Danish Defence
At fortælle livet - Samtale med Joakim Garff
Dette omfattende interview med Joakim Garff blev til i anledning af udgivelsen af hans meget roste biografi SAK om Søren Kierkegaard. Gennem temaer som eksempelvis æstetisk/biografisk, dekonstruktion og teologi, lidenskab, drift og skrift bringes vi rundt i forskellige hjørner og afkroge af Kierkegaard og Kierkegaard-forskningen
Family studies to find rare high risk variants in migraine
INTRODUCTION: Migraine has long been known as a common complex disease caused by genetic and environmental factors. The pathophysiology and the specific genetic susceptibility are poorly understood. Common variants only explain a small part of the heritability of migraine. It is thought that rare genetic variants with bigger effect size may be involved in the disease. Since migraine has a tendency to cluster in families, a family approach might be the way to find these variants. This is also indicated by identification of migraine-associated loci in classical linkage-analyses in migraine families. A single migraine study using a candidate-gene approach was performed in 2010 identifying a rare mutation in the TRESK potassium channel segregating in a large family with migraine with aura, but this finding has later become questioned. The technologies of next-generation sequencing (NGS) now provides an affordable tool to investigate the genetic variation in the entire exome or genome. The family-based study design using NGS is described in this paper. We also review family studies using NGS that have been successful in finding rare variants in other common complex diseases in order to argue the promising application of a family approach to migraine. METHOD: PubMed was searched to find studies that looked for rare genetic variants in common complex diseases through a family-based design using NGS, excluding studies looking for de-novo mutations, or using a candidate-gene approach and studies on cancer. All issues from Nature Genetics and PLOS genetics 2014, 2015 and 2016 (UTAI June) were screened for relevant papers. Reference lists from included and other relevant papers were also searched. For the description of the family-based study design using NGS an in-house protocol was used. RESULTS: Thirty-two successful studies, which covered 16 different common complex diseases, were included in this paper. We also found a single migraine study. Twenty-three studies found one or a few family specific variants (less than five), while other studies found several possible variants. Not all of them were genome wide significant. Four studies performed follow-up analyses in unrelated cases and controls and calculated odds ratios that supported an association between detected variants and risk of disease. Studies of 11 diseases identified rare variants that segregated fully or to a large degree with the disease in the pedigrees. CONCLUSION: It is possible to find rare high risk variants for common complex diseases through a family-based approach. One study using a family approach and NGS to find rare variants in migraine has already been published but with strong limitations. More studies are under way. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s10194-017-0729-y) contains supplementary material, which is available to authorized users
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