498 research outputs found
Validation of Danish wind time series from a new global renewable energy atlas for energy system analysis
We present a new high-resolution global renewable energy atlas ({REatlas})
that can be used to calculate customised hourly time series of wind and solar
PV power generation. In this paper, the atlas is applied to produce
32-year-long hourly model wind power time series for Denmark for each
historical and future year between 1980 and 2035. These are calibrated and
validated against real production data from the period 2000 to 2010. The high
number of years allows us to discuss how the characteristics of Danish wind
power generation varies between individual weather years. As an example, the
annual energy production is found to vary by from the average.
Furthermore, we show how the production pattern change as small onshore
turbines are gradually replaced by large onshore and offshore turbines.
Finally, we compare our wind power time series for 2020 to corresponding data
from a handful of Danish energy system models. The aim is to illustrate how
current differences in model wind may result in significant differences in
technical and economical model predictions. These include up to
differences in installed capacity and differences in system reserve
requirements
Enhanced electron correlations in FeSb
FeSb has been recently identified as a new model system for studying
many-body renormalizations in a -electron based narrow gap semiconducting
system, strongly resembling FeSi. The electron-electron correlations in
FeSb manifest themselves in a wide variety of physical properties including
electrical and thermal transport, optical conductivity, magnetic
susceptibility, specific heat and so on. We review some of the properties that
form a set of experimental evidences revealing the crucial role of correlation
effects in FeSb. The metallic state derived from slight Te doping in
FeSb, which has large quasiparticle mass, will also be introduced.Comment: 9 pages, 7 figures; submitted to Annalen der Physi
Effects of trophic status, water level, and temperature on shallow lake metabolism and metabolic balance: A standardized panâEuropean mesocosm experiment
Important drivers of gross primary production (GPP) and ecosystem respiration (ER) in lakes are temperature, nutrients, and light availability, which are predicted to be affected by climate change. Little is known about how these three factors jointly influence shallow lakes metabolism and metabolic status as net heterotrophic or autotrophic. We conducted a panâEuropean standardized mesocosm experiment covering a temperature gradient from Sweden to Greece to test the differential temperature sensitivity of GPP and ER at two nutrient levels (mesotrophic or eutrophic) crossed with two water levels (1 m and 2 m) to simulate different light regimes. The findings from our experiment were compared with predictions made according the metabolic theory of ecology (MTE). GPP and ER were significantly higher in eutrophic mesocosms than in mesotrophic ones, and in shallow mesocosms compared to deep ones, while nutrient status and depth did not interact. The estimated temperature gains for ER of ~â0.62âeV were comparable with those predicted by MTE. Temperature sensitivity for GPP was slightly higher than expected ~â0.54âeV, but when corrected for daylight length, it was more consistent with predictions from MTE ~â0.31âeV. The threshold temperature for the switch from autotrophy to heterotrophy was lower under mesotrophic (~â11°C) than eutrophic conditions (~â20°C). Therefore, despite a lack of significant temperatureâtreatment interactions in driving metabolism, the mesocosm's nutrient level proved to be crucial for how much warming a system can tolerate before it switches from net autotrophy to net heterotrophy
Clinical manifestations in infants and children with <i>Mycoplasma pneumoniae </i>infection
Mycoplasma pneumoniae is a common cause of community-acquired pneumonia in older children. Pulmonary and extra-pulmonary symptoms associated with M. pneumoniae infection are reported. M. pneumoniae is mainly epidemic in Denmark with the recurrence every 4-7th year.Retrospectively, to describe the epidemiology and clinical features, in infants and children, during the M. pneumoniae epidemic in 2010 and 2011.All children under the age of 16 that were tested for M. pneumoniae during the period 01.02.2010-31.01.2012 were included. Medical charts, as well as radiological findings, were reviewed for all children with M. pneumoniae. A post-hoc analysis of viral co-infections was done on part of the cohort.134 of 746 children were tested positive for M. pneumoniae by PCR or serology. Positive tests were found in 65% of children seven years and older, in 30% of 2-6-year-olds and 4% of infants (less than two years of age). Viral co-infection was found in 27% of the tested samples. The clinical presentation was a cough, asthma-like symptoms and low-grade fever. Extra-pulmonary symptoms were common and presented as nausea/vomiting by 33% of the children and skin manifestations by 25%. 84% of the children had a chest x-ray taken, and there were positive radiological findings in 94% of these.M. pneumoniae also affected infants and young children and symptoms were similar to infections with respiratory viruses, but severe LRTI were also seen. During an up-coming epidemic, assessment of extra-pulmonary manifestations can be helpful when diagnosing M. pneumoniae infections
Optimized planar photonic crystal waveguide 60° bend with more than 200 nm wide 1-dB transmission bandwidth
Effects of smartphone diaries and personal dosimeters on behavior in a randomized study of methods to document sunlight exposure
AbstractDosimeters and diaries have previously been used to evaluate sun-related behavior and UV exposure in local samples. However, wearing a dosimeter or filling in a diary may cause a behavioral change. The aim of this study was to examine possible confounding factors for a questionnaire validation study. We examined the effects of wearing dosimeters and filling out diaries, measurement period and recall effect on the sun-related behavior in Denmark in 2012.Our sample included 240 participants eligible by smartphone status and who took a vacation during weeks 26â32 in 2012, randomized by gender, age, education and skin type to six groups: 1) Control+diary, 2) Control, 3) 1-week dosimetry measurement, 4) 1-week dosimetry measurement+diary, 5) 3-week dosimetry measurement and 6) 1-week dosimetry measurement with 4week delayed questionnaire.Correlation coefficients between reported outdoor time and registered outdoor time for groups 3â6 were 0.39, 0.45, 0.43 and 0.09, respectively. Group 6 was the only group not significantly correlated. Questionnaire reported outdoor exposure time was shorter in the dosimeter measurement groups (3â6) than in their respective controls.We showed that using a dosimeter or keeping a diary seems to increase attention towards the behavior examined and therefore may influence this behavior. Receiving the questionnaire with 4week delay had a significant negative influence on correlation and recall of sunburn. When planning future UV behavior questionnaire validations, we suggest to use a 1-week interval for dosimetry measurements, no diary, and to minimize the time from end of measurement to filling out questionnaires
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