TY  - JOUR
A1  - Kramer, Alexander
A1  - Bangert, Philip
A1  - Schilling, Klaus
T1  - UWE-4: First Electric Propulsion on a 1U CubeSat — In-Orbit Experiments and Characterization
JF  - Aerospace
N2  - The electric propulsion system NanoFEEP was integrated and tested in orbit on the UWE-4 satellite, which marks the first successful demonstration of an electric propulsion system on board a 1U CubeSat. In-orbit characterization measurements of the heating process of the propellant and the power consumption of the propulsion system at different thrust levels are presented. Furthermore, an analysis of the thrust vector direction based on its effect on the attitude of the spacecraft is described. The employed heater liquefies the propellant for a duration of 30 min per orbit and consumes 103 ± 4 mW. During this time, the respective thruster can be activated. The propulsion system including one thruster head, its corresponding heater, the neutralizer and the digital components of the power processing unit consume 8.5 ± 0.1 mW ⋅μ A\(^{−1}\) + 184 ± 8.5 mW and scales with the emitter current. The estimated thrust directions of two thruster heads are at angles of 15.7 ± 7.6∘ and 13.2 ± 5.5∘ relative to their mounting direction in the CubeSat structure. In light of the very limited power on a 1U CubeSat, the NanoFEEP propulsion system renders a very viable option. The heater of subsequent NanoFEEP thrusters was already improved, such that the system can be activated during the whole orbit period.
KW  - CubeSat
KW  - UWE-4
KW  - electric propulsion
KW  - NanoFEEP
KW  - power consumption
KW  - thrust direction
KW  - characterization
KW  - in-orbit experiments
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-236124
VL  - 7
IS  - 7
ER  - 
TY  - JOUR
A1  - Dörhöfer, Lena
A1  - Lammert, Alexander
A1  - Krane, Vera
A1  - Gorski, Mathias
A1  - Banas, Bernhard
A1  - Wanner, Christoph
A1  - Krämer, Bernhard K.
A1  - Heid, Iris M.
A1  - Böger, Carsten A.
T1  - Study design of DIACORE (DIAbetes COhoRtE) - a cohort study of patients with diabetes mellitus type 2
JF  - BMC Medical Genetics
N2  - Background: Diabetes mellitus type 2 (DM2) is highly associated with increased risk for chronic kidney disease (CKD), end stage renal disease (ESRD) and cardiovascular morbidity. Epidemiological and genetic studies generate hypotheses for innovative strategies in DM2 management by unravelling novel mechanisms of diabetes complications, which is essential for future intervention trials. We have thus initiated the DIAbetes COhoRtE study (DIACORE). 
Methods: DIACORE is a prospective cohort study aiming to recruit 6000 patients of self-reported Caucasian ethnicity with prevalent DM2 for at least 10 years of follow-up. Study visits are performed in University-based recruiting clinics in Germany using standard operating procedures. All prevalent DM2 patients in outpatient clinics surrounding the recruiting centers are invited to participate. At baseline and at each 2-year follow-up examination, patients are subjected to a core phenotyping protocol. This includes a standardized online questionnaire and physical examination to determine incident micro-and macrovascular DM2 complications, malignancy and hospitalization, with a primary focus on renal events. Confirmatory outcome information is requested from patient records. Blood samples are obtained for a centrally analyzed standard laboratory panel and for biobanking of aliquots of serum, plasma, urine, mRNA and DNA for future scientific use. A subset of the cohort is subjected to extended phenotyping, e. g. sleep apnea screening, skin autofluorescence measurement, non-mydriatic retinal photography and non-invasive determination of arterial stiffness. 
Discussion: DIACORE will enable the prospective evaluation of factors involved in DM2 complication pathogenesis using high-throughput technologies in biosamples and genetic epidemiological studies.
KW  - chronic kidney-disease
KW  - stage renal-disease
KW  - glomerular-filtration-rate
KW  - genome-wide association
KW  - blood-glucose control
KW  - genetics
KW  - serum creatinine
KW  - cardiovascular disease
KW  - replacement therapy
KW  - United States
KW  - risk factors
KW  - diabetes mellitus type 2
KW  - diabetic nephropathy
KW  - end stage renal disease
KW  - cardiovascular morbidity
KW  - diabetes complications
KW  - epidemiology
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-122040
SN  - 1471-2350
VL  - 14
IS  - 25
ER  - 
TY  - JOUR
A1  - Schmidt, Enno
A1  - Sticherling, Michael
A1  - Sárdy, Miklós
A1  - Eming, Rüdiger
A1  - Goebeler, Matthias
A1  - Hertl, Michael
A1  - Hofmann, Silke C.
A1  - Hunzelmann, Nicolas
A1  - Kern, Johannes S.
A1  - Kramer, Harald
A1  - Nast, Alexander
A1  - Orzechowski, Hans‐Dieter
A1  - Pfeiffer, Christiane
A1  - Schuster, Volker
A1  - Sitaru, Cassian
A1  - Zidane, Miriam
A1  - Zillikens, Detlef
A1  - Worm, Margitta
T1  - S2k guidelines for the treatment of pemphigus vulgaris/foliaceus and bullous pemphigoid: 2019 update
JF  - JDDG: Journal der Deutschen Dermatologischen Gesellschaft
KW  - pemphigus vulgaris
KW  - pemphigus foliaceus
KW  - S2k guidelines
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-217806
VL  - 18
IS  - 5
SP  - 516
EP  - 526
ER  - 
TY  - THES
A1  - Kramer, Alexander
T1  - Orbit control of a very small satellite using electric propulsion
T1  - Orbitregelung eines Kleinstsatelliten mithilfe eines elektrischen Antriebssystems
N2  - Miniaturized satellites on a nanosatellite scale below 10kg of total mass contribute most to the number of launched satellites into Low Earth Orbit today. This results from the potential to design, integrate and launch these space missions within months at very low costs. In the past decade, the reliability in the fields of system design, communication, and attitude control have matured to allow for competitive applications in Earth observation, communication services, and science missions. The capability of orbit control is an important next step in this development, enabling operators to adjust orbits according to current mission needs and small satellite formation flight, which promotes new measurements in various fields of space science. Moreover, this ability makes missions with altitudes above the ISS comply with planned regulations regarding collision avoidance maneuvering.
This dissertation presents the successful implementation of orbit control capabilities on the pico-satellite class for the first time. This pioneering achievement is demonstrated on the 1U CubeSat UWE–4. A focus is on the integration and operation of an electric propulsion system on miniaturized satellites. Besides limitations in size, mass, and power of a pico-satellite, the choice of a suitable electric propulsion system was driven by electromagnetic cleanliness and the use as a combined attitude and orbit control system. Moreover, the integration of the propulsion system leaves the valuable space at the outer faces of the CubeSat structure unoccupied for future use by payloads. The used NanoFEEP propulsion system consists of four thruster heads, two neutralizers and two Power Processing Units (PPUs).
The thrusters can be used continuously for 50 minutes per orbit after the liquefaction of the propellant by dedicated heaters. The power consumption of a PPU with one activated thruster, its heater and a neutralizer at emitter current levels of 30-60μA or thrust levels of 2.6-5.5μN, respectively, is in the range of 430-1050mW. Two thruster heads were activated within the scope of in-orbit experiments. The thrust direction was determined using a novel algorithm within 15.7° and 13.2° of the mounting direction. Despite limited controllability of the remaining thrusters, thrust vector pointing was achieved using the magnetic actuators of the Attitude and Orbit Control System.
In mid 2020, several orbit control maneuvers changed the altitude of UWE–4, a first for pico-satellites. During the orbit lowering scenario with a duration of ten days, a single thruster head was activated in 78 orbits for 5:40 minutes per orbit. This resulted in a reduction of the orbit altitude by about 98.3m and applied a Delta v of 5.4cm/s to UWE–4. The same thruster was activated in another experiment during 44 orbits within five days for an average duration of 7:00 minutes per orbit. The altitude of UWE–4 was increased by about 81.2m and a Delta v of 4.4cm/s was applied. Additionally, a collision avoidance maneuver was executed in July 2020, which increased the distance of closest approach to the object by more than 5000m.
N2  - Heutzutage werden überwiegend Kleinstsatelliten in niedrige Erdumlaufbahnen befördert, da dies schnell und sehr kostengünstig möglich ist. Von der Planung bis zum Raketenstart vergehen oft nur wenige Monate. Im vergangenen Jahrzehnt haben sich Kleinstsatelliten bezüglich Systemgestaltung, Kommunikation und Lageregelung dahingehend weiterentwickelt, dass diese in den Anwendungsbereichen Erdbeobachtung, Kommunikationsdienstleistungen und wissenschaftlichen Missionen mit herkömmlichen Satelliten konkurrieren können. Ein weiterer wichtiger Entwicklungsschritt für Kleinstsatelliten wäre die Möglichkeit der Orbitkontrolle. Diese würde die Betreiber befähigen, die Flugbahn der Satelliten entsprechend den aktuellen Zielen der Mission anzupassen und Formationsflug von Kleinstsatelliten durchzuführen, um neue wissenschaftliche Erkenntnisse in vielen Bereichen der Weltraumforschung zu fördern. Gleichzeitig würden Kleinstsatelliten den aktuell
geplanten Vorschriften Rechnung tragen, nach denen Satelliten mit Flughöhen oberhalb der ISS manövrierfähig sein müssen, um Kollisionen zu vermeiden.
Die vorliegende Dissertation präsentiert die erste erfolgreiche Orbitkontrolle auf einem Piko-Satelliten. Diese Pionierleistung wird auf dem 1U CubeSat UWE–4 demonstriert. Ein Schwerpunkt dieser Arbeit liegt dabei auf der Integration und dem Betrieb eines elektrischen Antriebssystems auf Kleinstsatelliten. Diese Integration des Antriebssystems hält den wertvollen Platz an den Außenflächen des CubeSats für zukünftige Nutzlasten frei und ermöglicht dessen Anwendung als
Lage- und Orbitregelungsaktuator. Das verwendete NanoFEEP Antriebssystem beinhaltet vier Triebwerke, zwei Neutralisatoren und zwei Platinen zur Steuerung.
Nach der Verflüssigung des Treibstoffs durch dedizierte Heizer können die Triebwerke pro Erdumrundung für 50 Minuten kontinuierlich genutzt werden. Der Stromverbrauch einer Steuerplatine mit einem aktiven Triebwerk, seinem Heizer und einem Neutralisator bei Emitterströmen von 30-60μA bzw. Schüben von 2.6-5.5μN liegt im Bereich von 430-1050mW. Im Rahmen von In-
Orbit Experimenten wurden zwei Triebwerke aktiviert. Die Schubrichtungen der aktiven Triebwerke konnten mit einem neuartigen Algorithmus in einem Winkel von 15.7° bzw. 13.2° bezüglich ihrer Einbaurichtung bestimmt werden. Trotz mangelnder Steuerbarkeit der verbleibenden Triebwerke konnte eine Ausrichtung des Schubvektors unter Zuhilfenahme der magnetischen Aktuatoren des Lageregelungssystems erreicht werden.
Mehrere Orbitregelungsexperimente zur Veränderung der Flughöhe konnten Mitte 2020 zum ersten Mal auf einem Piko-Satelliten gezeigt werden. Um die Flughöhe zu verringern, wurde ein Triebwerk über einen Zeitraum von zehn Tagen während 78 Orbits gefeuert, wobei dieses pro Erdumrundung für durchschnittlich 5:40 Minuten aktiviert wurde. Hierdurch wurde die Flughöhe von UWE–4 um 98m reduziert und seine Geschwindigkeit um ein Delta v von 7.2cm/s erhöht. In einem anderen Experiment wurde dasselbe Triebwerk während 44 Orbits in einem Zeitraum von fünf Tagen für durchschnittlich 7:00 Minuten aktiviert, wodurch die Flughöhe des Kleinstsatelliten um 74.2m angehoben und seine Geschwindigkeit um ein Delta v von 4.0cm/s verringert wurde. Zudem wurde
ein Manöver zur Kollisionsvermeidung durchgeführt, das den Abstand zwischen UWE–4 und dem Objekt auf Kollisionskurs zum Zeitpunkt der kleinsten Annäherung um mehr als 5000m vergrößert hat.
T3  - Forschungsberichte in der Robotik = Research Notes in Robotics - 22 
KW  - Kleinsatellit
KW  - Plasmaantrieb
KW  - Flugbahn
KW  - Flughöhe
KW  - Kollisionsschutz
KW  - CubeSat
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-241552
SN  - 978-3-945459-34-8 (online)
ER  - 
TY  - JOUR
A1  - Carsten A., Böger
A1  - Gorski, Mathias
A1  - Li, Man
A1  - Hoffmann, Michael M.
A1  - Huang, Chunmei
A1  - Yang, Qiong
A1  - Teumer, Alexander
A1  - Krane, Vera
A1  - O'Seaghdha, Conall M.
A1  - Kutalik, Zoltán
A1  - Wichmann, H.-Erich
A1  - Haak, Thomas
A1  - Boes, Eva
A1  - Coassin, Stefan
A1  - Coresh, Josef
A1  - Kollerits, Barbara
A1  - Haun, Margot
A1  - Paulweber, Bernhard
A1  - Köttgen, Anna
A1  - Li, Guo
A1  - Shlipak, Michael G.
A1  - Powe, Neil
A1  - Hwang, Shih-Jen
A1  - Dehghan, Abbas
A1  - Rivadeneira, Fernando
A1  - Uitterlinden, André
A1  - Hofman, Albert
A1  - Beckmann, Jacques S.
A1  - Krämer, Bernhard K.
A1  - Witteman, Jacqueline
A1  - Bochud, Murielle
A1  - Siscovick, David
A1  - Rettig, Rainer
A1  - Kronenberg, Florian
A1  - Wanner, Christoph
A1  - Thadhani, Ravi I.
A1  - Heid, Iris M.
A1  - Fox, Caroline S.
A1  - Kao, W.H.
T1  - Association of eGFR-Related Loci Identified by GWAS with Incident CKD and ESRD
JF  - PLoS Genetics
N2  - Family studies suggest a genetic component to the etiology of chronic kidney disease (CKD) and end stage renal disease (ESRD). Previously, we identified 16 loci for eGFR in genome-wide association studies, but the associations of these single nucleotide polymorphisms (SNPs) for incident CKD or ESRD are unknown. We thus investigated the association of these loci with incident CKD in 26,308 individuals of European ancestry free of CKD at baseline drawn from eight population-based cohorts followed for a median of 7.2 years (including 2,122 incident CKD cases defined as eGFR < 60ml/min/1.73m(2) at follow-up) and with ESRD in four case-control studies in subjects of European ancestry (3,775 cases, 4,577 controls). SNPs at 11 of the 16 loci (UMOD, PRKAG2, ANXA9, DAB2, SHROOM3, DACH1, STC1, SLC34A1, ALMS1/NAT8, UBE2Q2, and GCKR) were associated with incident CKD; p-values ranged from p = 4.1e-9 in UMOD to p = 0.03 in GCKR. After adjusting for baseline eGFR, six of these loci remained significantly associated with incident CKD (UMOD, PRKAG2, ANXA9, DAB2, DACH1, and STC1). SNPs in UMOD (OR = 0.92, p = 0.04) and GCKR (OR = 0.93, p = 0.03) were nominally associated with ESRD. In summary, the majority of eGFR-related loci are either associated or show a strong trend towards association with incident CKD, but have modest associations with ESRD in individuals of European descent. Additional work is required to characterize the association of genetic determinants of CKD and ESRD at different stages of disease progression.
KW  - Chronic Kidney-disease
KW  - Stage renal-disease
KW  - Glomerular-filtration-rate
KW  - Diabetic-nephropathy
KW  - General-population
KW  - African-americans
KW  - Risk
KW  - Progression
KW  - Mortality
KW  - Variants
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-133758
VL  - 7
IS  - 9
ER  -