Experimentelle Untersuchung der bipolaren Diffusionsbeladung von Aerosolen mit Weichröntgenstrahlung sowie der Nanopartikelbildung unter Weichröntgenstrahlung

In dieser Diplomarbeit wurde die elektrostatische Partikelbeladung von Aerosolteilchen durch Weichröntgenstrahlung sowie die Nanopartikelbildung unter dem Einfluss von Weichröntgenstrahlung experimentell untersucht. Es wurde auch das Mobilitätsspektrum der durch die Weichröntgenstrahlung gebildeten Ionen beider Polaritäten gemessen. Außerdem wurden die wichtigsten theoretischen Berechnungen der Ladungsverteilung von Aerosolteilchen durch bipolare Diffusionsbeladung wie auch die vorhandene Literatur zum Thema der elektrostatischen Partikelbeladung durch Weichröntgenstrahlung behandelt. Das Spektrum der durch die Weichröntgenstrahlung gebildeten Ionen zeigte eine ähnliche Verteilung wie das jener Ionen, die durch eine radioaktive Quelle erzeugt wurden. Jedoch konnte durch die Weichröntgenstrahlung eine höhere Ionenkonzentration erzielt werden. Die gemessene Konzentration erwies sich aber als stark abhängig von der Geometrie der verwendeten Ionisationskammer bzw. der Wegstrecke der Ionen von der Erzeugung bis zum Detektor. Bei verschiedenen Flussraten durch die Ionisationskammer wurden keine nennenswerten Unterschiede des Ionenspektrums gefunden, ebenso bei einer Auskleidung der Innenseite der Ionisationskammer mit verschiedenen Metallen. Im Vergleich zu Ionen, erzeugt von einer radioaktiven Quelle, bilden sich durch Weichröntgenstrahlung auch weitaus mehr größere Ionen (in einem Bereich von 1,3 - 1,6 nm). Außerdem konnte eine Veränderung des Ionenspektrums bei Verwendung von befeuchteter Luft als Trägergas gemessen werden, sowohl bei positiven Ionen (Ausbildung eines weiteren Peaks bei 1 nm) als auch bei negativen (Anwachsen der Größe um etwa 0,1 nm). Es hat sich gezeigt, dass in Luft unter dem Einfluss von Weichröntgenstrahlung Partikel, mit einem Durchmesser in der Größenordnung von 10 nm, gebildet werden. Der Großteil dieser Partikel (> 90 %) ist elektrostatisch neutral. Es konnten Betriebsbedingungen gefunden werden, bei denen nur noch eine kaum messbare Partikelbildung aufgetreten ist, nämlich durch Verwendung von Luft aus einem Membrantrockner (VarioDry FRL SF 0010, Donaldson, USA). Auch wenn diese Luft über eine Acetonoberfläche geführt wurde, konnte keine Partikelbildung gemessen werden. Wurde jedoch die trockene Luft über eine Wasseroberfläche geführt, konnte eine Partikelbildung gemessen werden, und es zeigte sich ein Zusammenhang zwischen relativer Luftfeuchtigkeit und Partikelbildung. Die gebildeten Partikel sind stabil, und die positiv geladenen Partikel sind in ihrem Größenspektrum in guter Näherung log-normalverteilt. Die Partikelbildung ist stark abhängig von der Aufenthaltsdauer im Einflussbereich der Weichröntgenstrahlung. Eine Abhängigkeit der Partikelbildung vom Material, aus dem der Charger gefertigt ist, konnte nicht gemessen werden. Die bipolare Diffusionsbeladung durch Weichröntgenstrahlung zeigte teilweise deutliche Unterschiede zu der Beladung durch eine radioaktive Quelle (Am-241). Für die Messung der Beladung von monodispersen Partikeln wurden DEHS- und PSL-Aerosole verwendet, in einem Größenbereich von 20 bis 180 nm. Das gemessene Verhältnis von geladenen Partikeln durch Weichröntgenstrahlung zu geladenen Partikeln durch Am-241 ist in etwa proportional ist zum Logarithmus des Partikeldurchmessers. An der Untergrenze des gemessenen Bereiches ist dieses Verhältnis etwa 1, an der oberen Grenze 1,35 bis 1,40. Durch die Verwendung von Weichröntgenstrahlung wird also immer eine gleiche oder etwas bessere Beladung als durch eine radioaktive Quelle erziehlt. Bei einer Messung mit Ferritin-Partikeln (12 nm) wurden am Verteilungsmaximum bei der Beladung mit Weichröntgenstrahlung nur etwa halb so viele Partikel gemessen wie bei der Beladung durch Am-241. Außerdem war die Verteilung durch die Beladung mit Weichröntgenstrahlung breiter und die Lage des Maximums um 1 nm in Richtung größere Partikel verschoben. Die Ursachen für diese Unterschiede sind noch ungeklärt. Die Messung der Beladung eines polydispersen DEHS-Aerosols zeigte ein unerwartetes Ergebnis. Hier war das Verhältnis von Partikeln, beladen durch Weichröntgenstrahlung, im Vergleich zu denen, die durch eine radioaktive Quelle beladen wurden, im Bereich von 20 bis 100 nm teils deutlich kleiner als 1. Es konnte jedoch auch hier ein Anstieg der Beladungseffizienz mit der Partikelgröße durch Weichröntgenstrahlung im Vergleich zu einer radioaktiven Quelle festgestellt werden.This diploma thesis presents the results of the experimental investigation of the bipolar diffusion charging of aerosols by means of soft X-rays as well as the nanoparticle formation in a soft X-ray charger. Two Photoionizers (L9491, Hamamatsu Photonics, Japan) mounted on a self designed chamber made of aluminium were used to generate the X-rays. A second chamber with identical geometric dimensions containing a radioactive source (Po-210 or Am-241) was used as a radioactive charger for comparison measurements. Experiments with monodisperse aerosols (DEHS and PSL) in the size range from 20 to 180 nm showed, that the charging efficiency of the X-ray charger is up to 35 - 40 % higher than the efficiency of a radioactive charger. Measurements with polydisperse aerosols reveal a result that differs from the measurements with monodisperse aerosols; a discrepancy which requires further research. In the scope of investigation of the usability of the soft X-rays to condition the electrostatic charge on aerosol particles a substantial level of nanoparticle formation was observed. The mean diameter of the formed particles is about 10 nm and most of them (> 90 %) are electrostatically neutral. It was found that the particle formation depends on the relative humidity and the residence time of the particles in the charger. Experiments with a filtered room air, dried with a membrane-dryer to RH values below 1 % show negligible particle formation. These particle formation effects were not observed in chargers equipped with radioactive sources. In this work electrical mobility spectra of the ions generated in the soft X-ray charger where experimentally determined. Electrical mobility spectra of ions produced by means of soft X-rays show very similar morphology to the ions generated with radioactive sources, however with the abundance in favour of the X-rays. Discussion of the most important theories describing the bipolar diffusion charging process of aerosols, and a chapter discussing the still rather limited literature about the topic of the bipolar diffusion charging of aerosols by means of soft X-rays completes this diploma thesis

Funktionen gesundheitsbezogener Selbstorganisation: eine Analyse am Beispiel einer österreichischen Untersuchung

"In den vergangenen Jahren wird ein starker Anstieg von gesundheitsbezogenen Selbsthilfegruppen in vielfältigen Formen beobachtet. Der Artikel will durch die theoretische Ableitung gesellschaftlicher Funktionen und eine Analyse empirischer Daten zentrale Unterschiede in diesem Feld herausarbeiten. Drei Funktionen werden theoretisch abgeleitet: 'wechselseitige Unterstützung', 'komplementäre Dienstleistung durch individuelle Unterstützung' und 'kollektive Interessenvertretung'. Die empirische Analyse im Rahmen einer aktuellen österreichischen Untersuchung zeigt: Der überwiegende Teil der Gruppen kann anhand verschiedener Kombinationen dieser Funktionen in Form von drei Typen beschrieben werden; Organisationsstrukturen, Aktivitäten, Ressourcenbedarf und Umweltbeziehungen dieser Typen von Gruppen unterscheiden sich deutlich und konsistent mit den theoretischen Annahmen." (Autorenreferat)"In recent years, an increase of health-related self-help groups can be observed. This article wants to work out key differences in the field based on a theoretical analysis of societal functions and a review of empirical data. Three functions of self-help groups are derived from theoretical considerations: 'mutual support', 'complementary service provision through individual support', and a 'collective representation of interests'. An empirical analysis, in context of a most recent and comprehensive Austrian study, shows that most of the health-related self-help groups can be described in three types, representing various combinations of these functions. Organizational structures, activities, the need for resources and external relations of these types of groups differ significantly and in accordance with the theoretical assumptions." (author's abstract

Asteroseismology of massive stars with the TESS mission: the runaway Beta Cep pulsator PHL 346 = HN Aqr

We report an analysis of the first known Beta Cep pulsator observed by the TESS mission, the runaway star PHL 346 = HN Aqr. The star, previously known as a singly-periodic pulsator, has at least 34 oscillation modes excited, 12 of those in the g-mode domain and 22 p modes. Analysis of archival data implies that the amplitude and frequency of the dominant mode and the stellar radial velocity were variable over time. A binary nature would be inconsistent with the inferred ejection velocity from the Galactic disc of 420 km/s, which is too large to be survivable by a runaway binary system. A kinematic analysis of the star results in an age constraint (23 +- 1 Myr) that can be imposed on asteroseismic modelling and that can be used to remove degeneracies in the modelling process. Our attempts to match the excitation of the observed frequency spectrum resulted in pulsation models that were too young. Hence, asteroseismic studies of runaway pulsators can become vital not only in tracing the evolutionary history of such objects, but to understand the interior structure of massive stars in general. TESS is now opening up these stars for detailed asteroseismic investigation.Comment: accepted for ApJ

The APOKASC Catalog: An Asteroseismic and Spectroscopic Joint Survey of Targets in the Kepler Fields

We present the first APOKASC catalog of spectroscopic and asteroseismic properties of 1916 red giants observed in the Kepler fields. The spectroscopic parameters provided from the Apache Point Observatory Galactic Evolution Experiment project are complemented with asteroseismic surface gravities, masses, radii, and mean densities determined by members of the Kepler Asteroseismology Science Consortium. We assess both random and systematic sources of error and include a discussion of sample selection for giants in the Kepler fields. Total uncertainties in the main catalog properties are of order 80 K in Teff , 0.06 dex in [M/H], 0.014 dex in log g, and 12% and 5% in mass and radius, respectively; these reflect a combination of systematic and random errors. Asteroseismic surface gravities are substantially more precise and accurate than spectroscopic ones, and we find good agreement between their mean values and the calibrated spectroscopic surface gravities. There are, however, systematic underlying trends with Teff and log g. Our effective temperature scale is between 0-200 K cooler than that expected from the Infrared Flux Method, depending on the adopted extinction map, which provides evidence for a lower value on average than that inferred for the Kepler Input Catalog (KIC). We find a reasonable correspondence between the photometric KIC and spectroscopic APOKASC metallicity scales, with increased dispersion in KIC metallicities as the absolute metal abundance decreases, and offsets in Teff and log g consistent with those derived in the literature. We present mean fitting relations between APOKASC and KIC observables and discuss future prospects, strengths, and limitations of the catalog data.Comment: 49 pages. ApJSupp, in press. Full machine-readable ascii files available under ancillary data. Categories: Kepler targets, asteroseismology, large spectroscopic survey

Extensive study of HD 25558, a long-period double-lined binary with two SPB components

We carried out an extensive observational study of the Slowly Pulsating B (SPB) star, HD 25558. The ≈2000 spectra obtained at different observatories, the ground-based and MOST satellite light curves revealed that this object is a double-lined spectroscopic binary with an orbital period of about nine years. The observations do not allow the inference of an orbital solution. We determined the physical parameters of the components, and found that both lie within the SPB instability strip. Accordingly, both show line-profile variations due to stellar pulsations. 11 independent frequencies were identified in the data. All the frequencies were attributed to one of the two components based on pixel-by-pixel variability analysis of the line profiles. Spectroscopic and photometric mode identification was also performed for the frequencies of both stars. These results suggest that the inclination and rotation of the two components are rather different. The primary is a slow rotator with ≈6 d period, seen at ≈60° inclination, while the secondary rotates fast with ≈1.2 d period, and is seen at ≈20° inclination. Spectropolarimetric measurements revealed that the secondary component has a magnetic field with at least a few hundred Gauss strength, while no magnetic field can be detected in the primary

The Second APOKASC Catalog: The Empirical Approach

We present a catalog of stellar properties for a large sample of 6676 evolved stars with APOGEE spectroscopic parameters and \textit{Kepler} asteroseismic data analyzed using five independent techniques. Our data includes evolutionary state, surface gravity, mean density, mass, radius, age, and the spectroscopic and asteroseismic measurements used to derive them. We employ a new empirical approach for combining asteroseismic measurements from different methods, calibrating the inferred stellar parameters, and estimating uncertainties. With high statistical significance, we find that asteroseismic parameters inferred from the different pipelines have systematic offsets that are not removed by accounting for differences in their solar reference values. We include theoretically motivated corrections to the large frequency spacing ($\Delta \nu$) scaling relation, and we calibrate the zero point of the frequency of maximum power ($\nu_{\rm max}$) relation to be consistent with masses and radii for members of star clusters. For most targets, the parameters returned by different pipelines are in much better agreement than would be expected from the pipeline-predicted random errors, but 22\% of them had at least one method not return a result and a much larger measurement dispersion. This supports the usage of multiple analysis techniques for asteroseismic stellar population studies. The measured dispersion in mass estimates for fundamental calibrators is consistent with our error model, which yields median random and systematic mass uncertainties for RGB stars of order 4\%. Median random and systematic mass uncertainties are at the 9\% and 8\% level respectively for RC stars.Comment: 29 pages, 26 figures. Submitted ApJSupp. Comments welcome. For access to the main data table (Table 5) use https://www.dropbox.com/s/k33td8ukefwy5tv/APOKASC2_Table5.txt?dl=0; for access to the individual pipeline values (Table 6) use https://www.dropbox.com/s/vl9s2p3obftrv8m/APOKASC2_Table6.txt?dl=

Observation of viscosity transition in α-pinene secondary organic aerosol

Under certain conditions, secondary organic aerosol (SOA) particles can exist in the atmosphere in an amorphous solid or semi-solid state. To determine their relevance to processes such as ice nucleation or chemistry occurring within particles requires knowledge of the temperature and relative humidity (RH) range for SOA to exist in these states. In the Cosmics Leaving Outdoor Droplets (CLOUD) experiment at The European Organisation for Nuclear Research (CERN), we deployed a new in situ optical method to detect the viscous state of α-pinene SOA particles and measured their transition from the amorphous highly viscous state to states of lower viscosity. The method is based on the depolarising properties of laboratory-produced non-spherical SOA particles and their transformation to non-depolarising spherical particles at relative humidities near the deliquescence point. We found that particles formed and grown in the chamber developed an asymmetric shape through coagulation. A transition to a spherical shape was observed as the RH was increased to between 35 % at −10 °C and 80 % at −38 °C, confirming previous calculations of the viscosity-transition conditions. Consequently, α-pinene SOA particles exist in a viscous state over a wide range of ambient conditions, including the cirrus region of the free troposphere. This has implications for the physical, chemical, and ice-nucleation properties of SOA and SOA-coated particles in the atmosphere

Observation of viscosity transition in alpha-pinene secondary organic aerosol

Under certain conditions, secondary organic aerosol (SOA) particles can exist in the atmosphere in an amorphous solid or semi-solid state. To determine their relevance to processes such as ice nucleation or chemistry occurring within particles requires knowledge of the temperature and relative humidity (RH) range for SOA to exist in these states. In the Cosmics Leaving Outdoor Droplets (CLOUD) experiment at The European Organisation for Nuclear Research (CERN), we deployed a new in situ optical method to detect the viscous state of alpha-pinene SOA particles and measured their transition from the amorphous highly viscous state to states of lower viscosity. The method is based on the depolarising properties of laboratory-produced non-spherical SOA particles and their transformation to non-depolarising spherical particles at relative humidities near the deliquescence point. We found that particles formed and grown in the chamber developed an asymmetric shape through coagulation. A transition to a spherical shape was observed as the RH was increased to between 35aEuro-% at -10aEuro-A degrees C and 80aEuro-% at -38aEuro-A degrees C, confirming previous calculations of the viscosity-transition conditions. Consequently, alpha-pinene SOA particles exist in a viscous state over a wide range of ambient conditions, including the cirrus region of the free troposphere. This has implications for the physical, chemical, and ice-nucleation properties of SOA and SOA-coated particles in the atmosphere.Peer reviewe

The 13th Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-IV Survey Mapping Nearby Galaxies at Apache Point Observatory

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) began observations in July 2014. It pursues three core programs: APOGEE-2,MaNGA, and eBOSS. In addition, eBOSS contains two major subprograms: TDSS and SPIDERS. This paper describes the first data release from SDSS-IV, Data Release 13 (DR13), which contains new data, reanalysis of existing data sets and, like all SDSS data releases, is inclusive of previously released data. DR13 makes publicly available 1390 spatially resolved integral field unit observations of nearby galaxies from MaNGA,the first data released from this survey. It includes new observations from eBOSS, completing SEQUELS. In addition to targeting galaxies and quasars, SEQUELS also targeted variability-selected objects from TDSS and X-ray selected objects from SPIDERS. DR13 includes new reductions ofthe SDSS-III BOSS data, improving the spectrophotometric calibration and redshift classification. DR13 releases new reductions of the APOGEE-1data from SDSS-III, with abundances of elements not previously included and improved stellar parameters for dwarf stars and cooler stars. For the SDSS imaging data, DR13 provides new, more robust and precise photometric calibrations. Several value-added catalogs are being released in tandem with DR13, in particular target catalogs relevant for eBOSS, TDSS, and SPIDERS, and an updated red-clump catalog for APOGEE.This paper describes the location and format of the data now publicly available, as well as providing references to the important technical papers that describe the targeting, observing, and data reduction. The SDSS website, http://www.sdss.org, provides links to the data, tutorials and examples of data access, and extensive documentation of the reduction and analysis procedures. DR13 is the first of a scheduled set that will contain new data and analyses from the planned ~6-year operations of SDSS-IV.PostprintPeer reviewe