TY - JOUR A1 - Weber, Stephanie A1 - Puta, Christian A1 - Lesinski, Melanie A1 - Gabriel, Brunhild A1 - Steidten, Thomas A1 - Bär, Karl-Jürgen A1 - Herbsleb, Marco A1 - Granacher, Urs A1 - Gabriel, Holger H. W. T1 - Symptoms of anxiety and depression in young athletes using the hospital anxiety and depression scale JF - Frontiers in physiology N2 - Elite young athletes have to cope with multiple psychological demands such as training volume, mental and physical fatigue, spatial separation of family and friends or time management problems may lead to reduced mental and physical recovery. While normative data regarding symptoms of anxiety and depression for the general population is available (Hinz and Brahler, 2011), hardly any information exists for adolescents in general and young athletes in particular. Therefore, the aim of this study was to assess overall symptoms of anxiety and depression in young athletes as well as possible sex differences. The survey was carried out within the scope of the study "Resistance Training in Young Athletes" (KINGS-Study). Between August 2015 and September 2016, 326 young athletes aged (mean +/- SD) 14.3 +/- 1.6 years completed the Hospital Anxiety and Depression Scale (HAD Scale). Regarding the analysis of age on the anxiety and depression subscales, age groups were classified as follows: late childhood (12-14 years) and late adolescence (15-18 years). The participating young athletes were recruited from Olympic weight lifting, handball, judo, track and field athletics, boxing, soccer, gymnastics, ice speed skating, volleyball, and rowing. Anxiety and depression scores were (mean +/- SD) 4.3 +/- 3.0 and 2.8 +/- 2.9, respectively. In the subscale anxiety, 22 cases (6.7%) showed subclinical scores and 11 cases (3.4%) showed clinical relevant score values. When analyzing the depression subscale, 31 cases (9.5%) showed subclinical score values and 12 cases (3.7%) showed clinically important values. No significant differences were found between male and female athletes (p >= 0.05). No statistically significant differences in the HADS scores were found between male athletes of late childhood and late adolescents (p >= 0.05). To the best of our knowledge, this is the first report describing questionnaire based indicators of symptoms of anxiety and depression in young athletes. Our data implies the need for sports medical as well as sports psychiatric support for young athletes. In addition, our results demonstrated that the chronological classification concerning age did not influence HAD Scale outcomes. Future research should focus on sports medical and sports psychiatric interventional approaches with the goal to prevent anxiety and depression as well as teaching coping strategies to young athletes. KW - youth athletes KW - anxiety KW - depression KW - gender differences KW - late childhood KW - adolescents Y1 - 2018 U6 - https://doi.org/10.3389/fphys.2018.00182 SN - 1664-042X VL - 9 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Hortobagyi, Tibor A1 - Uematsu, Azusa A1 - Sanders, Lianne A1 - Kliegl, Reinhold A1 - Tollar, Jozsef A1 - Moraes, Renato A1 - Granacher, Urs T1 - Beam Walking to Assess Dynamic Balance in Health and Disease BT - a Protocol for the "BEAM" Multicenter Observational Study JF - Gerontology N2 - Background: Dynamic balance keeps the vertical projection of the center of mass within the base of support while walking. Dynamic balance tests are used to predict the risks of falls and eventual falls. The psychometric properties of most dynamic balance tests are unsatisfactory and do not comprise an actual loss of balance while walking. Objectives: Using beam walking distance as a measure of dynamic balance, the BEAM consortium will determine the psychometric properties, lifespan and patient reference values, the relationship with selected “dynamic balance tests,” and the accuracy of beam walking distance to predict falls. Methods: This cross-sectional observational study will examine healthy adults in 7 decades (n = 432) at 4 centers. Center 5 will examine patients (n = 100) diagnosed with Parkinson’s disease, multiple sclerosis, stroke, and balance disorders. In test 1, all participants will be measured for demographics, medical history, muscle strength, gait, static balance, dynamic balance using beam walking under single (beam walking only) and dual task conditions (beam walking while concurrently performing an arithmetic task), and several cognitive functions. Patients and healthy participants age 50 years or older will be additionally measured for fear of falling, history of falls, miniBESTest, functional reach on a force platform, timed up and go, and reactive balance. All participants age 50 years or older will be recalled to report fear of falling and fall history 6 and 12 months after test 1. In test 2, seven to ten days after test 1, healthy young adults and age 50 years or older (n = 40) will be retested for reliability of beam walking performance. Conclusion: We expect to find that beam walking performance vis-à-vis the traditionally used balance outcomes predicts more accurately fall risks and falls. Clinical Trial Registration Number: NCT03532984. KW - Aging KW - Gait KW - Balance KW - Dual tasks KW - Falls Y1 - 2018 U6 - https://doi.org/10.1159/000493360 SN - 0304-324X SN - 1423-0003 VL - 65 IS - 4 SP - 332 EP - 339 PB - Karger CY - Basel ER - TY - JOUR A1 - Puta, Christian A1 - Steidten, Thomas A1 - Baumbach, Philipp A1 - Woehrl, Toni A1 - May, Rico A1 - Kellmann, Michael A1 - Herbsleb, Marco A1 - Gabriel, Brunhild A1 - Weber, Stephanie A1 - Granacher, Urs A1 - Gabriel, Holger H. W. T1 - Standardized assessment of resistance training-Induced subjective symptoms and objective signs of immunological stress responses in young athletes JF - Frontiers in physiology N2 - From a health and performance-related perspective, it is crucial to evaluate subjective symptoms and objective signs of acute training-induced immunological responses in young athletes. The limited number of available studies focused on immunological adaptations following aerobic training. Hardly any studies have been conducted on resistance-training induced stress responses. Therefore, the aim of this observational study was to investigate subjective symptoms and objective signs of immunological stress responses following resistance training in young athletes. Fourteen (7 females and 7 males) track and field athletes with a mean age of 16.4 years and without any symptoms of upper or lower respiratory tract infections participated in this study. Over a period of 7 days, subjective symptoms using the Acute Recovery and Stress Scale (ARSS) and objective signs of immunological responses using capillary blood markers were taken each morning and after the last training session. Differences between morning and evening sessions and associations between subjective and objective parameters were analyzed using generalized estimating equations (GEE). In post hoc analyses, daily change-scores of the ARSS dimensions were compared between participants and revealed specific changes in objective capillary blood samples. In the GEE models, recovery (ARSS) was characterized by a significant decrease while stress (ARSS) showed a significant increase between morning and evening-training sessions. A concomitant increase in white blood cell count (WBC), granulocytes (GRAN) and percentage shares of granulocytes (GRAN%) was found between morning and evening sessions. Of note, percentage shares of lymphocytes (LYM%) showed a significant decrease. Furthermore, using multivariate regression analyses, we identified that recovery was significantly associated with LYM%, while stress was significantly associated with WBC and GRAN%. Post hoc analyses revealed significantly larger increases in participants' stress dimensions who showed increases in GRAN%. For recovery, significantly larger decreases were found in participants with decreases in LYM% during recovery. More specifically, daily change-scores of the recovery and stress dimensions of the ARSS were associated with specific changes in objective immunological markers (GRAN%, LYM%) between morning and evening-training sessions. Our results indicate that changes of subjective symptoms of recovery and stress dimensions using the ARSS were associated with specific changes in objectively measured immunological markers. KW - immune system KW - strength training KW - track and field KW - youth KW - Acute Recovery and Stress Scale (ARSS) Y1 - 2018 U6 - https://doi.org/10.3389/fphys.2018.00698 SN - 1664-042X VL - 9 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Verch, Ronald A1 - Hirschmüller, Anja A1 - Müller, Juliane A1 - Baur, Heiner A1 - Mayer, Frank A1 - Müller, Steffen T1 - Is in-toing gait physiological in children? BT - Results of a large cohort study in 5910 healthy (pre-) school children JF - Gait & posture N2 - Research question: This study aimed to establish reference values in 1-14 year old healthy children and to implement FPA-percentile curves for daily clinical use. Methods: 5910 healthy children performed at least 3 repetitions of barefoot walking over an instrumented walkway using a pressure measurement platform. The FPA [degrees] was extracted and analyzed by age and gender (mean +/- standard deviation; median with percentiles, MANOVA (age, gender) and Wilcoxon-Signed-Rank test for intra-individual side differences (alpha = 0.05). Results: FPA maximum was observed in 2-year-old children and diminished significant until the age of 4 to moderate out-toeing. For ages 5-14, no statistically significant differences in FPA values were present (p > 0.05). MANOVA confirmed age (p < 0.001) and gender (p < 0.001) as significant FPA influencing factors, without combined effect (p > 0.05). In every age group, right feet showed significantly greater out-toeing (p < 0.05). Significance: Percentile values indicate a wide FPA range in children. FPA development in young children shows a spontaneous shift towards moderate external rotation (age 2-4), whereby in-toeing <= 1-5 degrees can be present, but can return to normal. Bilateral in-toeing after the age of four and unilateral in-toeing after the age of seven should be monitored. KW - Foot progression angle KW - Children KW - In-toeing KW - Out-toeing KW - Gait Y1 - 2018 U6 - https://doi.org/10.1016/j.gaitpost.2018.08.019 SN - 0966-6362 SN - 1879-2219 VL - 66 SP - 70 EP - 75 PB - Elsevier CY - Clare ER - TY - JOUR A1 - Koziel, Slawomir A1 - Scheffler, Christiane A1 - Tutkuviene, Janina A1 - Jakimaviciene, Egle Marija A1 - Mumm, Rebekka A1 - Barbieri, Davide A1 - Godina, Elena A1 - El-Shabrawi, Mortada A1 - Elhusseini, Mona A1 - Musalek, Martin A1 - Pruszkowska-Przybylska, Paulina A1 - El Dash, Hanaa H. A1 - Safar, Hebatalla Hassan A1 - Lehmann, Andreas A1 - Swanson, James A1 - Bogin, Barry A1 - Liu, Yuk-Chien A1 - Groth, Detlef A1 - Kirchengast, Sylvia A1 - Siniarska, Anna A1 - Nieczuja-Dwojacka, Joanna A1 - Kralik, Miroslav A1 - Satake, Takashi A1 - Harc, Tomasz A1 - Roelants, Mathieu A1 - Hermanussen, Michael T1 - Meeting Report: Growth and social environment BT - Proceedings of the 25th Aschauer Soiree, held at Krobielowice, Poland, November 18th 2017 JF - Pediatric Endocrinology Reviews N2 - Twenty-two scientists met at Krobielowice, Poland, to discuss the impact of the social environment, spatial proximity, migration, poverty, but also psychological factors such as body perception and satisfaction, and social stressors such as elite sports, and teenage pregnancies, on child and adolescent growth. The data analysis included linear mixed effects models with different random effects, Monte Carlo analyses, and network simulations. The work stressed the importance of the peer group, but also included historic material, some considerations about body proportions, and growth in chronic liver, and congenital heart disease. KW - Body height KW - Social environment KW - Strategic growth adjustment KW - Competitive growth KW - Community effects on growth Y1 - 2018 U6 - https://doi.org/10.17458/per.vol15.2018.ksh.mr.GrowthSocialEnvironment SN - 1565-4753 VL - 15 IS - 4 SP - 319 EP - 329 PB - Medical Media CY - Netanya ER - TY - THES A1 - Kramer, Hubertus T1 - Bürgerwindparks T2 - Schriften zum Umweltenergierecht ; 27 N2 - In Deutschland stößt der Ausbau der Windenergie mit dem zunehmenden Heranrücken an Wohnbebauungen immer häufiger auf Widerstand bei der lokalen Bevölkerung. Die Stärkung von Bürgerwindparks gegenüber dem alleinigen Betrieb durch große Energiekonzerne bildet die Chance wieder mehr Akzeptanz für die Windenergie zu schaffen. Das Werk widmet sich in diesem Zusammenhang einer Reihe von Fragestellungen, die verschiedene Rechtsgebiete berühren. Angesichts nur noch begrenzt zur Verfügung stehender Windenergieflächen wird untersucht, ob und mit welchen Mitteln, beispielsweise des Raumordnungs- und Bauplanungsrechts sowie vertraglicher Instrumente, Flächen speziell für Bürgerwindparks gesichert werden können. Daneben erfährt der Leser in welchem Rahmen die Regelungen des Kommunalwirtschaftsrechts Gemeinden eine Beteiligung an Bürgerwindparks erlauben. Schließlich werden verschiedenste Gesellschaftsformen daraufhin analysiert, ob sie sich als Organisationsform eines Bürgerwindparks eignen. Y1 - 2018 SN - 978-3-8487-4668-2 PB - Nomos CY - Baden-Baden ER - TY - THES A1 - Heise, Kristian T1 - Haushaltssperren im Recht des Bundes, der Länder und der Kommunen T2 - Schriften zum öffentlichen Recht ; 1366 N2 - Die Arbeit widmet sich den Haushaltssperren auf den verschiedenen Ebenen und untersucht, ob ein einheitliches Instrument der Haushaltssperre im deutschen Recht existiert, oder ob sich hinter dem Begriff der Haushaltssperre verschiedene haushaltsrechtliche Maßnahmen verbergen. Dazu werden auf verfassungsrechtlicher Ebene der Aspekt der Gewaltenteilung gemäß Art. 20 II 2 GG sowie die kommunale Selbstverwaltungsgarantie des Art. 28 II GG betrachtet. Auf Bundes-, Landes- und kommunaler Ebene werden u.a. Sperrvermerke, Globale Minderausgaben, haushaltswirtschaftliche Sperren sowie Bewirtschaftungssperren eingehend dargestellt und erörtert. Ergänzend werden Aspekte wie weitere Instrumente zur Kontrolle des Haushalts und Rechtsschutz gegen Haushaltssperren dargestellt und Regelungsvorschläge unterbreitet. Im Fazit wird festgestellt, dass »Haushaltssperren« zu komplex und unterschiedlich sind, um ein einheitliches Institut der Haushaltssperre darstellen zu können. Y1 - 2018 SN - 978-3-428-15404-3 PB - Duncker & Humblot CY - Berlin ER - TY - THES A1 - Markmann, Friedrich T1 - Lokale Leistungserbringung im kommunalen Interesse BT - Revival der Genossenschaft? T2 - Kommunalrechtliche Studien ; 6 N2 - Genossenschaften haben wieder Konjunktur. Sie betätigen sich in einer Vielzahl von Einsatzfeldern, die herkömmlicherweise den kommunalen Selbstverwaltungsaufgaben zufallen. Darüber hinaus ergänzen und ersetzen Genossenschaften das kommunale Leistungsangebot durch die Erledigung von Aufgaben, auf deren Erbringung die Kommunen selbst verzichten. In der Praxis haben sich hybride Kooperationsmodelle gebildet, die eine Vielzahl unterschiedlicher Akteure vereinen und damit für die lokale Leistungserbringung im kommunalen Interesse fernab einer einseitigen Bindung an „Staat“ oder „Privat“ einen „Dritten Weg“ eröffnen. Davon ausgehend untersucht der Verfasser, ob und unter welchen Voraussetzungen es sich bei der Genossenschaft um einen nachhaltigen Partner der Kommunen bei der Aufrechterhaltung kommunaler Infrastrukturen handeln kann. Y1 - 2018 SN - 978-3-8487-4929-4 PB - Nomos CY - Baden-Baden ER - TY - THES A1 - Matuschka, Philip T1 - Das Nonaffektationsprinzip BT - Der Haushaltsgrundsatz der Gesamtdeckung in Bund und Ländern, insbesondere rechtshistorische Entwicklung und Verfassungsrang T2 - Schriften zum öffentlichen Recht : SöR ; 1394 Y1 - 2018 UR - https://www.duncker-humblot.de/buch/das-nonaffektationsprinzip-9783428156054 SN - 978-3-428-15605-4 U6 - https://doi.org/10.3790/978-3-428-55605-2 SN - 0582-0200 PB - Duncker & Humblot CY - Berlin ER - TY - GEN A1 - Reindl, Nicole A1 - Finch, Nicolle L. A1 - Schaffenroth, Veronika A1 - Barstow, Martin A. A1 - Casewell, Sarah L. A1 - Geier, Stephan A1 - Bertolami Miller, Marcelo Miguel A1 - Taubenberger, Stefan T1 - Revealing the true nature of Hen2-428 T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - The nucleus of Hen 2-428 is a short orbital period (4.2 h) spectroscopic binary, whose status as potential supernovae type Ia progenitor has raised some controversy in the literature. We present preliminary results of a thorough analysis of this interesting system, which combines quantitative non-local thermodynamic (non-LTE) equilibrium spectral modelling, radial velocity analysis, multi-band light curve fitting, and state-of-the art stellar evolutionary calculations. Importantly, we find that the dynamical system mass that is derived by using all available He II lines does not exceed the Chandrasekhar mass limit. Furthermore, the individual masses of the two central stars are too small to lead to an SN Ia in case of a dynamical explosion during the merger process. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1129 KW - binaries: spectroscopic KW - stars: atmospheres KW - stars: abundances KW - Supernovae Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-459703 SN - 1866-8372 IS - 1129 ER - TY - JOUR A1 - Reindl, Nicole A1 - Finch, Nicolle L. A1 - Schaffenroth, Veronika A1 - Barstow, Martin A. A1 - Casewell, Sarah L. A1 - Geier, Stephan A1 - Bertolami Miller, Marcelo Miguel A1 - Taubenberger, Stefan T1 - Revealing the true nature of Hen 2-428 JF - Galaxies N2 - The nucleus of Hen 2-428 is a short orbital period (4.2 h) spectroscopic binary, whose status as potential supernovae type Ia progenitor has raised some controversy in the literature. We present preliminary results of a thorough analysis of this interesting system, which combines quantitative non-local thermodynamic (non-LTE) equilibrium spectral modelling, radial velocity analysis, multi-band light curve fitting, and state-of-the art stellar evolutionary calculations. Importantly, we find that the dynamical system mass that is derived by using all available He II lines does not exceed the Chandrasekhar mass limit. Furthermore, the individual masses of the two central stars are too small to lead to an SN Ia in case of a dynamical explosion during the merger process. KW - binaries: spectroscopic KW - stars: atmospheres KW - stars: abundances KW - supernovae Y1 - 2018 U6 - https://doi.org/10.3390/galaxies6030088 SN - 2075-4434 VL - 6 IS - 3 ER - TY - GEN A1 - Maier, Philipp A1 - Wolf, Jürgen A1 - Keilig, Thomas A1 - Krabbe, Alfred A1 - Duffard, Rene A1 - Ortiz, Jose-Luis A1 - Klinkner, Sabine A1 - Lengowski, Michael A1 - Müller, Thomas A1 - Lockowandt, Christian A1 - Krockstedt, Christian A1 - Kappelmann, Norbert A1 - Stelzer, Beate A1 - Werner, Klaus A1 - Geier, Stephan A1 - Kalkuhl, Christoph A1 - Rauch, Thomas A1 - Schanz, Thomas A1 - Barnstedt, Jürgen A1 - Conti, Lauro A1 - Hanke, Lars T1 - Towards a European Stratospheric Balloon Observatory BT - the ESBO design study T2 - Ground-based and Airborne Telescopes VII N2 - This paper presents the concept of a community-accessible stratospheric balloon-based observatory that is currently under preparation by a consortium of European research institutes and industry. We present the technical motivation, science case, instrumentation, and a two-stage image stabilization approach of the 0.5-m UV/visible platform. In addition, we briefly describe the novel mid-sized stabilized balloon gondola under design to carry telescopes in the 0.5 to 0.6 m range as well as the currently considered flight option for this platform. Secondly, we outline the scientific and technical motivation for a large balloon-based FIR telescope and the ESBO DS approach towards such an infrastructure. KW - astronomy KW - balloon telescopes KW - UV KW - far infrared KW - detectors KW - observatory Y1 - 2018 SN - 978-1-5106-1954-8 U6 - https://doi.org/10.1117/12.2319248 SN - 0277-786X SN - 1996-756X VL - 10700 PB - SPIE-INT Soc Optical Engineering CY - Bellingham ER - TY - JOUR A1 - Gerlach, Moritz Reinhardt T1 - Convergence of dynamics and the Perron-Frobenius operator JF - Israel Journal of Mathematics N2 - We complete the picture how the asymptotic behavior of a dynamical system is reflected by properties of the associated Perron-Frobenius operator. Our main result states that strong convergence of the powers of the Perron-Frobenius operator is equivalent to setwise convergence of the underlying dynamic in the measure algebra. This situation is furthermore characterized by uniform mixing-like properties of the system. Y1 - 2018 U6 - https://doi.org/10.1007/s11856-018-1671-7 SN - 0021-2172 SN - 1565-8511 VL - 225 IS - 1 SP - 451 EP - 463 PB - Hebrew univ magnes press CY - Jerusalem ER - TY - JOUR A1 - Fusillo, Nicola Pietro Gentile A1 - Tremblay, Pier-Emmanuel A1 - Gänsicke, Boris T. A1 - Manser, Christopher J. A1 - Cunningham, Tim A1 - Cukanovaite, Elena A1 - Hollands, Mark A1 - Marsh, Thomas A1 - Raddi, Roberto A1 - Jordan, Stefan A1 - Toonen, Silvia A1 - Geier, Stephan A1 - Barstow, Martin A1 - Cummings, Jeffrey D. T1 - A Gaia Data Release 2 catalogue of white dwarfs and a comparison with SDSS JF - Monthly notices of the Royal Astronomical Society N2 - We present a catalogue of white dwarf candidates selected from the second data release of Gaia (DR2). We used a sample of spectroscopically confirmed white dwarfs from the Sloan Digital Sky Survey (SDSS) to map the entire space spanned by these objects in the Gaia Hertzsprung–Russell diagram. We then defined a set of cuts in absolute magnitude, colour, and a number of Gaia quality flags to remove the majority of contaminating objects. Finally, we adopt a method analogous to the one presented in our earlier SDSS photometric catalogues to calculate a probability of being a white dwarf (PWD) for all Gaia sources that passed the initial selection. The final catalogue is composed of 486641 stars with calculated PWD from which it is possible to select a sample of ≃260000 high-confidence white dwarf candidates in the magnitude range 8 < G < 21. By comparing this catalogue with a sample of SDSS white dwarf candidates, we estimate an upper limit in completeness of 85 per cent for white dwarfs with G ≤ 20 mag and Teff >7000 K, at high Galactic latitudes (|b| > 20°). However, the completeness drops at low Galactic latitudes, and the magnitude limit of the catalogue varies significantly across the sky as a function of Gaia’s scanning law. We also provide the list of objects within our sample with available SDSS spectroscopy. We use this spectroscopic sample to characterize the observed structure of the white dwarf distribution in the H–R diagram. KW - catalogues KW - surveys KW - white dwarfs Y1 - 2018 U6 - https://doi.org/10.1093/mnras/sty3016 SN - 0035-8711 SN - 1365-2966 VL - 482 IS - 4 SP - 4570 EP - 4591 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Latour, Marilyn A1 - Randall, Suzanna K. A1 - Calamida, Annalisa A1 - Geier, Stephan A1 - Moehler, Sabine T1 - The ultimate spectroscopic census of extreme horizontal branch stars in omega Centauri JF - Astronomy and astrophysics : an international weekly journal N2 - The presence of extreme horizontal branch (EHB) and blue hook stars in some Galactic globular clusters (GGCs) constitutes one of the remaining mysteries of stellar evolution. While several evolutionary scenarios have been proposed to explain the characteristics of this peculiar population of evolved stars, their observational verification has been limited by the availability of spectroscopic data for a statistically significant sample of such objects in any single GGC. We recently launched the SHOTGLAS project with the aim of providing a comprehensive picture of this intriguing stellar population in terms of spectroscopic properties for all readily accessible GGCs hosting an EHB. In this first paper, we focus on omega Cen, a peculiar, massive GGC that hosts multiple stellar populations. We use non-LTE model atmospheres to derive atmospheric parameters (Te ff, log g and N(He) / N(H)) and spectroscopic masses for 152 EHB stars in the cluster. This constitutes the largest spectroscopic sample of EHB stars ever analyzed in a GGC and represents similar to 20% of the EHB population of omega Cen. We also search for close binaries among these stars based on radial velocity variations. Our results show that the EHB population of omega Cen is divided into three spectroscopic groups that are very distinct in the Te ff helium abundance plane. The coolest sdB-type stars (Te ff. 30 000 K) have a hydrogen-rich atmosphere, populate the theoretical EHB region in the Te ff log g plane, and form 26% of our sample. The hottest sdO-type stars (Te ff & 42 000 K) make up 10% of the sample, have a hydrogen-rich atmosphere and are thought to be in a post-EHB evolutionary phase. The majority of our sample is found at intermediate temperatures and consists of sdOB stars that have roughly solar or super-solar atmospheric helium abundances. It is these objects that constitute the blue hook at V > 18 : 5 mag in the omega Cen color-magnitude diagram. Interestingly, the helium-enriched sdOBs do not have a significant counterpart population in the Galactic field, indicating that their formation is dependent on the particular environment found in omega Cen and other select GGCs. Another major di ff erence between the EHB stars in omega Cen and the field is the fraction of close binaries. From our radial velocity survey we identify two binary candidates, however no orbital solutions could be determined. We estimate an EHB close binary fraction of similar to 5% in omega Cen. This low fraction is in line with findings for other GGCs, but in sharp contrast to the situation in the field, where around 50% of the sdB stars reside in close binaries. Finally, the mass distribution derived is very similar for all three spectroscopic groups, however the average mass (0.38 M fi) is lower than that expected from stellar evolution theory. While this mass conundrum has previously been noted for EHB stars in omega Cen, it so far appears to be unique to that cluster. KW - stars: atmospheres KW - stars: horizontal-branch KW - subdwarfs KW - stars: fundamental parameters KW - binaries: close KW - globular clusters: individual: NGC5139 Y1 - 2018 U6 - https://doi.org/10.1051/0004-6361/201833129 SN - 1432-0746 VL - 618 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Reindl, Nicole A1 - Bainbridge, M. A1 - Przybilla, Norbert A1 - Geier, Stephan A1 - Prvak, M. A1 - Krticka, Jiri A1 - Ostensen, R. H. A1 - Telting, J. A1 - Werner, K. T1 - Unravelling the baffling mystery of the ultrahot wind phenomenon in white dwarfs JF - Monthly notices of the Royal Astronomical Society N2 - The presence of ultrahigh excitation (UHE) absorption lines (e.g. OVIII) in the optical spectra of several of the hottest white dwarfs poses a decades-long mystery and is something that has never been observed in any other astrophysical object. The occurrence of such features requires a dense environment with temperatures near 10(6) K, by far exceeding the stellar effective temperature. Here we report the discovery of a new hot wind white dwarf, GALEXJ014636.8+323615. Astonishingly, we found for the first time rapid changes of the equivalent widths of the UHE features, which are correlated to the rotational period of the star (P=0.242035 d). We explain this with the presence of a wind-fed circumstellar magnetosphere in which magnetically confined wind shocks heat up the material to the high temperatures required for the creation of the UHE lines. The photometric and spectroscopic variability of GALEXJ014636.8+323615 can then be understood as consequence of the obliquity of the magnetic axis with respect to the rotation axis of the white dwarf. This is the first time a wind-fed circumstellar magnetosphere around an apparently isolated white dwarf has been discovered and finally offers a plausible explanation of the ultrahot wind phenomenon. KW - stars: AGB and post-AGB KW - stars: evolution KW - stars: magnetic field Y1 - 2018 U6 - https://doi.org/10.1093/mnrasl/sly191 SN - 0035-8711 SN - 1365-2966 VL - 482 IS - 1 SP - L93 EP - L98 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Reindl, Nicole A1 - Geier, Stephan A1 - Ostensen, R. H. T1 - Discovery of two bright DO-type white dwarfs JF - Monthly notices of the Royal Astronomical Society N2 - We discovered two bright DO-type white dwarfs, GALEXJ053628.3+544854 (J0536+5448) and GALEXJ231128.0+292935(J2311+2929), which rank among the eight brightest DO-type white dwarfs known. Our non-LTE model atmosphere analysis reveals effective temperatures and surface gravities of T-eff = 80000 +/- 4600K and log g = 8.25 +/- 0.15 for J0536+5448 and T-eff = 69400 +/- 900K and log g = 7.80 +/- 0.06 for J2311+2929. The latter shows a significant amount of carbon in its atmosphere (C = 0.003(-0.002)(+0.005), by mass), while for J0536+5448 we could derive only an upper limit of C < 0.003. Furthermore, we calculated spectroscopic distances for the two stars and found a good agreement with the distances derived from the Gaia parallaxes. KW - stars: abundances KW - stars: atmospheres KW - white dwarfs Y1 - 2018 U6 - https://doi.org/10.1093/mnras/sty1875 SN - 0035-8711 SN - 1365-2966 VL - 480 IS - 1 SP - 1211 EP - 1217 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Gerlach, Moritz Reinhardt A1 - Glück, Jochen T1 - Lower bounds and the asymptotic behaviour of positive operator semigroups JF - Ergodic theory and dynamical systems N2 - If (T-t) is a semigroup of Markov operators on an L-1-space that admits a nontrivial lower bound, then a well-known theorem of Lasota and Yorke asserts that the semigroup is strongly convergent as t -> infinity. In this article we generalize and improve this result in several respects. First, we give a new and very simple proof for the fact that the same conclusion also holds if the semigroup is merely assumed to be bounded instead of Markov. As a main result, we then prove a version of this theorem for semigroups which only admit certain individual lower bounds. Moreover, we generalize a theorem of Ding on semigroups of Frobenius-Perron operators. We also demonstrate how our results can be adapted to the setting of general Banach lattices and we give some counterexamples to show optimality of our results. Our methods combine some rather concrete estimates and approximation arguments with abstract functional analytical tools. One of these tools is a theorem which relates the convergence of a time-continuous operator semigroup to the convergence of embedded discrete semigroups. Y1 - 2017 U6 - https://doi.org/10.1017/etds.2017.9 SN - 0143-3857 SN - 1469-4417 VL - 38 SP - 3012 EP - 3041 PB - Cambridge Univ. Press CY - New York ER - TY - GEN A1 - Stete, Felix A1 - Koopman, Wouter-Willem Adriaan A1 - Bargheer, Matias T1 - Signatures of strong coupling on nanoparticles BT - revealing absorption anticrossing by tuning the dielectric environment T2 - Quantum Nano-Photonics N2 - The electromagnetic coupling of molecular excitations to plasmonic nanoparticles offers a promising method to manipulate the light-matter interaction at the nanoscale. Plasmonic nanoparticles foster exceptionally high coupling strengths, due to their capacity to strongly concentrate the light-field to sub-wavelength mode volumes. A particularly interesting coupling regime occurs, if the coupling increases to a level such that the coupling strength surpasses all damping rates in the system. In this so-called strong-coupling regime hybrid light-matter states emerge, which can no more be divided into separate light and matter components. These hybrids unite the features of the original components and possess new resonances whose positions are separated by the Rabi splitting energy h Omega. Detuning the resonance of one of the components leads to an anticrossing of the two arising branches of the new resonances omega(+) and omega(-) with a minimal separation of Omega = omega(+) - omega(-). Y1 - 2018 SN - 978-94-024-1546-9 SN - 978-94-024-1544-5 SN - 978-94-024-1543-8 U6 - https://doi.org/10.1007/978-94-024-1544-5_53 SN - 1871-465X SP - 445 EP - 447 PB - Springer CY - Dordrecht ER - TY - GEN A1 - Stete, Felix A1 - Schossau, Phillip Gerald A1 - Koopman, Wouter-Willem Adriaan A1 - Bargheer, Matias T1 - Size Dependence of the Coupling Strength in Plasmon-Exciton Nanoparticles T2 - Quantum Nano-Photonics N2 - The coupling between molecular excitations and nanoparticles leads to promising applications. It is for example used to enhance the optical cross-section of molecules in surface enhanced Raman scattering, Purcell enhancement or plasmon enhanced dye lasers. In a coupled system new resonances emerge resulting from the original plasmon (ωpl) and exciton (ωex) resonances as ω±=12(ωpl+ωex)±14(ωpl−ωex)2+g2−−−−−−−−−−−−−−−√, (1) where g is the coupling parameter. Hence, the new resonances show a separation of Δ = ω+ − ω− from which the coupling strength can be deduced from the minimum distance between the two resonances, Ω = Δ(ω+ = ω−). Y1 - 2018 SN - 978-94-024-1546-9 SN - 978-94-024-1544-5 SN - 978-94-024-1543-8 U6 - https://doi.org/10.1007/978-94-024-1544-5_26 SN - 1871-465X SP - 381 EP - 383 PB - Springer CY - Dordrecht ER -