2,870 research outputs found

    Satellite image-based generation of high frequency solar radiation time series for the assessment of solar energy systems

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    Solar energy is envisaged as a major pillar of the global transition to a climate-friendly energy system. Variability of solar radiation requires additional balancing measures to ensure a stable and secure energy supply. In order to analyze this issue in detail, solar radiation time series data of appropriate temporal and spatial resolution is necessary. Common weather models and satellites are only delivering solar surface irradiance with temporal resolutions of up to 15 min. Significant short-term variability in irradiances within seconds to minutes however is induced by clouds. Ground-based measurements typically used to capture this variability are costly and only sparsely available. Hence, a method to synthetically generate time series from currently available satellite imagery is of value for researchers, grid operators, and project developers. There are efforts to increase satellite resolution to 1 min, but this is not planned everywhere and will not change the spatial resolution. Therefore, the fundamental question remains if there are alternative strategies to obtain high temporal resolution observations at a pinpoint. This paper presents a method to generate 1 min resolved synthetic time series of global and direct normal irradiances for arbitrary locations. A neural network based on satellite image derived cloud structure parameters enables to classify high-frequency solar radiation variability. Combined with clear-sky radiation data, 1 min time series which reflect the typical variability characteristics of a site are reproduced. Testing and validation against ground observations (BSRN) show that the method can accurately reproduce characteristics such as frequency and ramp distributions. An application case demonstrates the usage in low-voltage grid studies

    Genetische Aufarbeitung des Marburger Video-EEG-Monitoring-Patientenkollektivs

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    Angehörige von Patienten mit Epilepsie haben ein erhöhtes Risiko, ebenfalls eine Epilepsie zu entwickeln. Das Risiko fĂŒr Angehörige von Patienten mit genetisch (idiopathisch) generalisierten Epilepsien (GGE) ist höher als fĂŒr Angehörige von Patienten mit fokalen Epilepsien mit struktureller oder unbekannter Ursache, wie die die Werte in der Literatur zeigen. Bei Forschung zur Genetik von Epilepsien ist die Erhebung der Familienanamnese ein wichtiger Bestandteil. Die Hauptfragestellung dieser Studie waren die Erhebung der HĂ€ufigkeit der positiven Familienanamnese in dem Studienkollektiv und ob die Befragung eines Ă€lteren, weiblichen Familienmitglieds die Familienanamnese verbessern könnte. Dabei wurden die Patienten im VEM (Video-EEG-Monitoring) des „Epilepsiezent-rums der UniversitĂ€tsklinik Marburg“ der Jahre 2014 und 2015 untersucht. Die Ein-schlusskriterien dieser Studie erfĂŒllten 73 Patienten. Patienten mit strukturellen Epilepsien, außer Dysplasien und Hippocampussklerosen, waren ausgeschlossen. Die Altersspanne der Patienten reichte von 11-66 Jahren. Hatten diese Patienten der Teilnahme an der „Biobank fĂŒr paroxysmale neurologische Störungen“ zugestimmt, wurde versucht ein erneutes TelefongesprĂ€ch mit der Erhebung der Familienanamnese durchzufĂŒhren und mit einem weiteren Familienmitglied, meist der Mutter, ebenfalls die Familienanamnese zu erheben. Die Ergebnisse dieser Studie zeigen, dass auch Patientenkollektive mit einem hohen Anteil an medikamentenrefraktĂ€ren Patienten, wie im VEM, nicht selten eine positi-ve Familienanamnese aufweisen. In 37 % der Familien wurden weitere betroffene Familienmitglieder mit Epilepsien, FieberkrĂ€mpfen oder einmaligen AnfĂ€llen be-nannt. Sicher diagnostizierte Epilepsien fanden sich bei weiteren Angehörigen bei 23 % der Familien. Die HĂ€ufigkeit von betroffenen erstgradigen Angehörigen (1,8 %) war jedoch geringer als in populationsbasierten Studien. Auch die Werte fĂŒr generalisierte (2,6 %) und fĂŒr fokale Epilepsien (0,8 %) lagen niedriger als ver-gleichbare Werte in der Literatur. Es ist also sehr wahrscheinlich, dass dies mit dem hohen Teil der medikamentenrefraktĂ€ren Patienten in der untersuchten Kohorte zu-sammenhĂ€ngt. Auch wenn die Werte im Vergleich relativ gering sind, ist es unerlĂ€sslich eine genaue Erhebung der Familienanamnese in der Ă€rztlichen Anamnese, auch bei der DurchfĂŒhrung eines VEM, durchzufĂŒhren. Auswertungen der AngehörigengesprĂ€che zeigten, dass die Befragung eines Ă€lteren Angehörigen deutlich die SensitivitĂ€t fĂŒr eine positive Familienanamnese erhöht, vor allem bei Patienten im Alter zwischen 10 - 40 Jahren. Daher ist die DurchfĂŒhrung einer Angehörigenbefragung zur Familienanamnese, wenn möglich auch im Kliniksalltag, auf Grundlage der Ergebnisse dieser Studie zu empfehlen. Hier sind vor allem Zusatzgewinne in Bezug auf Verwandte außerhalb der Kernfamilie (erstgradige Verwandte) zu erwarten. Dies kann unter anderem Hinweise auf eine genetische Komponente in der Ätiologie der Epilepsie oder auf mögliche Syndrome in der Familie geben. In Bezug auf erstgradige Angehörige gab es in dieser Studie fast keinen Zusatznutzen, da bei diesem Verwandtschaftsgrad der Austausch oft ausreichend zu sein scheint

    Bone drilling with fiber guided excimer laser beam

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    Zur Ermittlung einer optimalen Parametereinstellung des Excimerlasers fĂŒr die Bearbeitung von Knochengewebe, testeten wir bei drei unterschiedlichen ImpulslĂ€ngen den Einfluß von Austrittsenergie und Repetitionsrate auf die Ablationstiefe.An experiment is presented which shows the relationship between energy, repetition rate and pulse width to the bone ablation rate using a fiber guided excimer laser beam

    The Nature of Infrared Emission in the Local Group Dwarf Galaxy NGC 6822 As Revealed by Spitzer

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    We present Spitzer imaging of the metal-deficient (Z ~30% Z_sun) Local Group dwarf galaxy NGC 6822. On spatial scales of ~130 pc, we study the nature of IR, H alpha, HI, and radio continuum emission. Nebular emission strength correlates with IR surface brightness; however, roughly half of the IR emission is associated with diffuse regions not luminous at H alpha (as found in previous studies). The global ratio of dust to HI gas in the ISM, while uncertain at the factor of ~2 level, is ~25 times lower than the global values derived for spiral galaxies using similar modeling techniques; localized ratios of dust to HI gas are about a factor of five higher than the global value in NGC 6822. There are strong variations (factors of ~10) in the relative ratios of H alpha and IR flux throughout the central disk; the low dust content of NGC 6822 is likely responsible for the different H alpha/IR ratios compared to those found in more metal-rich environments. The H alpha and IR emission is associated with high-column density (> ~1E21 cm^-2) neutral gas. Increases in IR surface brightness appear to be affected by both increased radiation field strength and increased local gas density. Individual regions and the galaxy as a whole fall within the observed scatter of recent high-resolution studies of the radio-far IR correlation in nearby spiral galaxies; this is likely the result of depleted radio and far-IR emission strengths in the ISM of this dwarf galaxy.Comment: ApJ, in press; please retrieve full-resolution version from http://www.astro.wesleyan.edu/~cannon/pubs.htm

    Hepatic artery reconstruction using an operating microscope in pediatric liver transplantation—Is it worth the effort?

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    Introduction: In pediatric liver transplantation (pLT), hepatic artery thrombosis (HAT) is associated with inferior transplant outcome. Hepatic artery reconstruction (HAR) using an operating microscope (OM) is considered to reduce the incidence of HAT. Methods: HAR using an OM was compared to a historic cohort using surgical loupes (SL) in pLT performed between 2009 and 2020. Primary endpoint was the occurrence of HAT. Secondary endpoints were 1-year patient and graft survival determined by Kaplan-Meier analysis and complications. Multivariate analysis was used to identify independent risk factors for HAT and adverse events. Results: A total of 79 pLTs were performed [30 (38.0%) living donations; 49 (62.0%) postmortem donations] divided into 23 (29.1%) segment 2/3, 32 (40.5%) left lobe, 4 (5.1%) extended right lobe, and 20 (25.3%) full-size grafts. One-year patient and graft survival were both 95.2% in the OM group versus 86.2% and 77.8% in the SL group (p = .276 and p = .077). HAT rate was 0% in the OM group versus 24.1% in the SL group (p = .013). One-year patient and graft survival were 64.3% and 35.7% in patient with HAT, compared to 93.9% and 92.8% in patients with no HAT (both p < .001). Multivariate analysis revealed HAR with SL (p = .022) and deceased donor liver transplantation (DDLT) (p = .014) as independent risk factors for HAT. The occurrence of HAT was independently associated with the need for retransplantation (p < .001) and biliary leakage (p = .045). Conclusion: In pLT, the use of an OM is significantly associated to reduce HAT rate, biliary complications, and graft loss and outweighs the disadvantages of delayed arterial perfusion and prolonged warm ischemia time (WIT)

    The ClinGen Epilepsy Gene Curation Expert Panel—Bridging the divide between clinical domain knowledge and formal gene curation criteria

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    The field of epilepsy genetics is advancing rapidly and epilepsy is emerging as a frequent indication for diagnostic genetic testing. Within the larger ClinGen framework, the ClinGen Epilepsy Gene Curation Expert Panel is tasked with connecting two increasingly separate fields: the domain of traditional clinical epileptology, with its own established language and classification criteria, and the rapidly evolving area of diagnostic genetic testing that adheres to formal criteria for gene and variant curation. We identify critical components unique to the epilepsy gene curation effort, including: (a) precise phenotype definitions within existing disease and phenotype ontologies; (b) consideration of when epilepsy should be curated as a distinct disease entity; (c) strategies for gene selection; and (d) emerging rules for evaluating functional models for seizure disorders. Given that de novo variants play a prominent role in many of the epilepsies, sufficient genetic evidence is often awarded early in the curation process. Therefore, the emphasis of gene curation is frequently shifted toward an iterative precuration process to better capture phenotypic associations. We demonstrate that within the spectrum of neurodevelopmental disorders, gene curation for epilepsy-associated genes is feasible and suggest epilepsy-specific conventions, laying the groundwork for a curation process of all major epilepsy-associated genes

    Medical and cardio-vascular emergency department visits during the COVID-19 pandemic in 2020: is there a collateral damage? A retrospective routine data analysis

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    Background In this retrospective routine data analysis, we investigate the number of emergency department (ED) consultations during the COVID-19 pandemic of 2020 in Germany compared to the previous year with a special focus on numbers of myocardial infarction and acute heart failure. Methods Aggregated case numbers for the two consecutive years 2019 and 2020 were obtained from 24 university hospitals and 9 non-university hospitals in Germany and assessed by age, gender, triage scores, disposition, care level and by ICD-10 codes including the tracer diagnoses myocardial infarction (I21) and heart failure (I50). Results A total of 2,216,627 ED consultations were analyzed, of which 1,178,470 occurred in 2019 and 1,038,157 in 2020. The median deviation in case numbers between 2019 and 2020 was - 14% [CI (- 11)-(- 16)]. After a marked drop in all cases in the first COVID-19 wave in spring 2020, case numbers normalized during the summer Thereafter starting in calendar week 39 case numbers constantly declined until the end of the year 2020. The decline in case numbers predominantly concerned younger [- 16%; CI (- 13)-(- 19)], less urgent [- 18%; CI (- 12)-(- 22)] and non-admitted cases [- 17%; CI (- 13)-(- 20)] in particular during the second wave. During the entire observation period admissions for chest pain [- 13%; CI (- 21)-2], myocardial infarction [- 2%; CI (- 9)-11] and heart failure [- 2%; CI (- 10)-6] were less affected and remained comparable to the previous year. Conclusions ED visits were noticeably reduced during both SARS-CoV-2 pandemic waves in Germany but cardiovascular diagnoses were less affected and no refractory increase was noted. However, long-term effects cannot be ruled out and need to be analysed in future studies. [GRAPHICS]
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