Towards a new image processing system at Wendelstein 7-X: From spatial calibration to characterization of thermal events

Wendelstein 7-X (W7-X) is the most advanced fusion experiment in the stellarator line and is aimed at proving that the stellarator concept is suitable for a fusion reactor. One of the most important issues for fusion reactors is the monitoring of plasma facing components when exposed to very high heat loads, through the use of visible and infrared (IR) cameras. In this paper, a new image processing system for the analysis of the strike lines on the inboard limiters from the first W7-X experimental campaign is presented. This system builds a model of the IR cameras through the use of spatial calibration techniques, helping to characterize the strike lines by using the information given by real spatial coordinates of each pixel. The characterization of the strike lines is made in terms of position, size, and shape, after projecting the camera image in a 2D grid which tries to preserve the curvilinear surface distances between points. The description of the strike-line shape is made by means of the Fourier Descriptors

Forward modeling of collective Thomson scattering for Wendelstein 7-X plasmas: Electrostatic approximation

In this paper, we present a method for numerical computation of collective Thomson scattering (CTS). We developed a forward model, eCTS, in the electrostatic approximation and benchmarked it against a full electromagnetic model. Differences between the electrostatic and the electromagnetic models are discussed. The sensitivity of the results to the ion temperature and the plasma composition is demonstrated. We integrated the model into the Bayesian data analysis framework Minerva and used it for the analysis of noisy synthetic data sets produced by a full electromagnetic model. It is shown that eCTS can be used for the inference of the bulk ion temperature. The model has been used to infer the bulk ion temperature from the first CTS measurements on Wendelstein 7-X

Pathogenicity and Impact of HLA Class I Alleles in Aplastic Anemia Patients of Different Ethnicities

Acquired aplastic anemia (AA) is caused by autoreactive T cell-mediated destruction of early hematopoietic cells. Somatic loss of human leukocyte antigen (HLA) class I alleles was identified as a mechanism of immune escape in surviving hematopoietic cells of some patients with AA. However, pathogenicity, structural characteristics, and clinical impact of specific HLA alleles in AA remain poorly understood. Here, we evaluated somatic HLA loss in 505 patients with AA from 2 multi-institutional cohorts. Using a combination of HLA mutation frequencies, peptide-binding structures, and association with AA in an independent cohort of 6,323 patients from the National Marrow Donor Program, we identified 19 AA risk alleles and 12 non-risk alleles and established a potentially novel AA HLA pathogenicity stratification. Our results define pathogenicity for the majority of common HLA-A/B alleles across diverse populations. Our study demonstrates that HLA alleles confer different risks of developing AA, but once AA develops, specific alleles are not associated with response to immunosuppression or transplant outcomes. However, higher pathogenicity alleles, particularly HLA-B*14:02, are associated with higher rates of clonal evolution in adult patients with AA. Our study provides insights into the immune pathogenesis of AA, opening the door to future autoantigen identification and improved understanding of clonal evolution in AA

Taming the tiger by the tail: modulation of DNA damage responses by telomeres

Telomeres are by definition stable and inert chromosome ends, whereas internal chromosome breaks are potent stimulators of the DNA damage response (DDR). Telomeres do not, as might be expected, exclude DDR proteins from chromosome ends but instead engage with many DDR proteins. However, the most powerful DDRs, those that might induce chromosome fusion or cell-cycle arrest, are inhibited at telomeres. In budding yeast, many DDR proteins that accumulate most rapidly at double strand breaks (DSBs), have important functions in physiological telomere maintenance, whereas DDR proteins that arrive later tend to have less important functions. Considerable diversity in telomere structure has evolved in different organisms and, perhaps reflecting this diversity, different DDR proteins seem to have distinct roles in telomere physiology in different organisms. Drawing principally on studies in simple model organisms such as budding yeast, in which many fundamental aspects of the DDR and telomere biology have been established; current views on how telomeres harness aspects of DDR pathways to maintain telomere stability and permit cell-cycle division are discussed

Climatic variations over the last 4000 cal yr BP in the western margin of the Tarim Basin, Xinjiang, reconstructed from pollen data

The nature of Holocene climate patterns and mechanisms in central Asia are open areas of inquiry. In this study, regional vegetation and climate dynamics over the last ca. 4000 years are reconstructed using a high resolution pollen record from the Kashgar oasis, on the western margin of the Tarim Basin, central Asia. Ephedra, Chenopodiaceae and Cannabaceae dominate the pollen assemblages, and Chenopodiaceae/Ephedra ratios and percentages of long-distance transported pollen taxa are used to infer regional variations in moisture and vegetation density. Three periods of increased humidity are identified, from ca. 4000-2620 cal yr BP, ca. 1750-1260 cal yr BP and ca. 550-390 cal yr BP and these periods coincide with the respective Holocene Bond Events 2,1 and 0, which are reported in the North Atlantic. Any increase in strength, or southward migration, of the mid-latitude westerlies would result in more precipitation and meltwater on mountains surrounding the study site. Warm and dry conditions are detected between ca.1260 and 840 cal yr BP (AD 690-1110), and cool and wet conditions are detected between ca. 840 and 680 cal yr BP (AD 1110-1270), during the Medieval Warm Period (ca. AD 800-1200). The climate variations in the Kashgar region over the last 4000 years appear to have been dominated by changes to the westerly circulation system and glacier dynamics on surrounding mountains. However, the question of whether the Asian monsoon delivers precipitation to the western Tarim Basin, a region that is influenced by several climate systems, is still open to debate.</p

Retention of hunter-gatherer economies among maritime foragers from Caleta Vitor, northern Chile, during the late Holocene: evidence from stable carbon and nitrogen isotopic analysis of skeletal remains

On the basis of stable carbon and nitrogen isotope analysis of human remains, this paper provides evidence for the retention of hunter-gatherer economies among coastal inhabitants in northern Chile during the late Holocene - at the same time that inland populations were adopting agricultural economies. Coastal diets from the Caleta Vitor region of the Atacama Desert were dominated by marine-based foods, predominantly from upper trophic levels. The focus on reliable marine food resources is interpreted as a risk minimisation strategy in this marginal arid environment. Although these coastal hunter-gatherers adopted other goods and traditions from agricultural populations, their participation in this larger interregional exchange network did not affect their basic subsistence economies. On the basis of stable carbon and nitrogen isotope analysis of human remains, this paper provides evidence for the retention of hunter-gatherer economies among coastal inhabitants in northern Chile during the late Holocene - at the same time that inland populations were adopting agricultural economies. Coastal diets from the Caleta Vitor region of the Atacama Desert were dominated by marine-based foods, predominantly from upper trophic levels. The focus on reliable marine food resources is interpreted as a risk minimisation strategy in this marginal arid environment. Although these coastal hunter-gatherers adopted other goods and traditions from agricultural populations, their participation in this larger interregional exchange network did not affect their basic subsistence economies. Associated new radiocarbon dates from the site are also discussed. Skeletal remains and artefacts associated with the Caleta Vitor shell middens generally originate from sites with dates ranging from c. 9000-476 BP. However, the human remains that are the subject of this research cover the time period c. 4000-476 BP.© 2013, Elsevier Ltd

Skeletal arsenic of the pre-Columbian population of Caleta Vitor, northern Chile

Exposure to toxic arsenic has severe health consequences for past and present societies. This research resolves changes in a pre-Industrial population's exposure to the toxin within an arsenic-endemic area of the Atacama Desert of northern Chile over long timescales. Inductively coupled plasma mass spectrometry (ICP-MS) trace element analysis of human bone and tooth samples from 21 burials at Caleta Vitor on the Pacific coast of northern Chile has established that the pre-Columbian inhabitants were exposed to elevated levels of arsenic where one third of the sample population had accumulated levels in their skeletal system indicative of chronic poisoning. Coupled with new accelerator mass spectrometry (AMS) radiocarbon ages for the skeletal samples, spanning c. 3867 to 474 cal BP and encompassing all major cultural periods of the region, these results demonstrate the continual risk of arsenic poisoning over several millennia of occupation at one site. Numerous factors may have partially contributed to the population's inferred poisoning, due to the complex interaction of various environmental sources of arsenic and human behaviours. Increased exposure to arsenic could relate to climatic variability influencing sources of drinking water or anthropogenic activities such as mining and metallurgy or dietary changes associated with agriculture. Assessment of these potential sources of arsenic toxication, including evaluation of modern environmental data from the region, suggests contaminated drinking water was the most likely cause of arseniasis. © 2015 Elsevier Ltd

Subsistence and the isotopic signature of herding in the Bronze Age Hexi Corridor, NW Gansu, China

Dietary patterns at two Bronze Age sites in the Hexi Corridor are investigated by the analysis of stable carbon and nitrogen isotopes in faunal bone collagen. The findings are compared with archaeobotanical remains from one of the sites which include high proportions of millet (Panicum miliaceum and Setaria italica) as well as the western derived cereals wheat (Triticum aestivum), barley (Hordeum vulgare) and oat (Avena sativa). The isotopic data indicate domestic omnivores (Canis and Sus) had diets dominated by millet. Minimally offset delta(15)N values between herbivore and omnivore fauna suggest low consumption of animal protein by omnivores. Diets of herded animal (Bos and Caprinae) included only low proportions of C4 foods, suggesting that these animals were not regularly foddered with millet plants, and that their grazing areas were mostly beyond the agricultural zone. The wide range in delta(15)N values amongst herbivore fauna (4.1 parts per thousand-11.8 parts per thousand) suggests grazing occurred in a variety of ecological zones, and this would be consistent with the occurrence of long-distance transport of livestock in the region.</p

Radar demonstrator for bird monitoring in wind farms

Potential collisions of birds with power plants frequently result in temporary shutdown of concerned turbines enforceable by law. Thus, the need of appropriate sensors for bird monitoring in wind farms is growing. As radar in general has the potential to become one of these sensors, a purpose-built demonstrator is presented in this work. It aims for investigating the chances and problems of radar for bird monitoring inside wind farms