1,111 research outputs found
Non-destructive testing of carbon reinforced plastics by means of phase retrieval
In this work, the SLM-based phase retrieval system will be used to inspect
carbon reinforced plastics samples (CFRP) under applying a thermal load. For
this purpose, the system is used to capture a sequence of 8 spatially separated
recording planes, where the distance between subsequent planes equals 2 mm. For
detecting the hidden failures two sets of intensity observations are recorded.
The first set for the initial state and the second set is captured after
applying the load. To recover the phase information associated with the two
states, the captured intensities have been subjected to an iterative algorithm
based on the method of generalized projection.Comment: Conf. Speckle 201
Precise Radial Velocities of Giant Stars VII. Occurrence Rate of Giant Extrasolar Planets as a Function of Mass and Metallicity
(abridged) We have obtained precise radial velocities for a sample of 373 G
and K type giants at Lick Observatory regularly over more than 12 years.
Planets have been identified around 15 giant stars; an additional 20 giant
stars host planet candidates. We investigate the occurrence rate of substellar
companions around giant stars as a function of stellar mass and metallicity. We
probe the stellar mass range from about 1 to beyond 3 M_Sun, which is not being
explored by main-sequence samples. We fit the giant planet occurrence rate as a
function of stellar mass and metallicity with a Gaussian and an exponential
distribution, respectively. We find strong evidence for a planet-metallicity
correlation among the secure planet hosts of our giant star sample, in
agreement with the one for main-sequence stars. However, the planet-metallicity
correlation is absent for our sample of planet candidates, raising the
suspicion that a good fraction of them might indeed not be planets. Consistent
with the results obtained by Johnson for subgiants, the giant planet occurrence
rate increases in the stellar mass interval from 1 to 1.9 M_Sun. However, there
is a maximum at a stellar mass of 1.9 +0.1/-0.5 M_Sun, and the occurrence rate
drops rapidly for masses larger than 2.5-3.0 M_Sun. We do not find any planets
around stars more massive than 2.7 M_Sun, although there are 113 stars with
masses between 2.7 and 5 M_Sun in our sample (corresponding to a giant planet
occurrence rate < 1.6% at 68.3% confidence in that stellar mass bin). We also
show that this result is not a selection effect related to the planet
detectability being a function of the stellar mass. We conclude that giant
planet formation or inward migration is suppressed around higher mass stars,
possibly because of faster disk depletion coupled with a longer migration
timescale.Comment: 13 pages plus long table appendix, accepted by A&
Searching for Earth-mass planets around Centauri: precise radial velocities from contaminated spectra
This work is part of an ongoing project which aims to detect terrestrial
planets in our neighbouring star system Centauri using the Doppler
method. Owing to the small angular separation between the two components of the
Cen AB binary system, the observations will to some extent be
contaminated with light coming from the other star. We are accurately
determining the amount of contamination for every observation by measuring the
relative strengths of the H- and NaD lines. Furthermore, we have
developed a modified version of a well established Doppler code that is
modelling the observations using two stellar templates simultaneously. With
this method we can significantly reduce the scatter of the radial velocity
measurements due to spectral cross-contamination and hence increase our chances
of detecting the tiny signature caused by potential Earth-mass planets. After
correcting for the contamination we achieve radial velocity precision of for a given night of observations. We have also
applied this new Doppler code to four southern double-lined spectroscopic
binary systems (HR159, HR913, HR7578, HD181958) and have successfully recovered
radial velocities for both components simultaneously.Comment: accepted for publication in the International Journal of Astrobiology
(published by Cambridge University Press); will appear in a revised form,
subsequent to editorial input by Cambridge University Pres
The role of heritage assets in public financial reporting : an assessment on the current status of financial reporting of heritage assets in Switzerland
In the wake of public financial management reforms, academics and practitioners have discussed and elaborated the impact of accounting reforms on heritage assets for more than three decades. Both national and international standard-setting bodies and the scientific community were not able to provide a common definition for heritage asset in an accounting context. This article presents the most relevant definitions used in public financial management as well as it elaborates on the critical issues concerning recognition, measurement and disclosure of heritage assets. Based on publicly accessible documents from twenty Swiss states and selected interviews with accounting officers from these states this paper presents an overview of what importance is being given to heritage assets in public financial reporting in Switzerland. The empirical results indicate that despite modern public financial management regimes (i.e. HAM2 or IPSAS) transparency regarding heritage assets remains very limited. As a result, recommendations for, but not limited to Switzerland are presented, which offer a possible approach to increase the level of information available on heritage assets in financial reporting
Bedeutung des FGFR4 Polymorphismus in der Pathogenese und Progression von Tumorerkrankungen
In der vorliegenden Arbeit wurde die Rolle des kĂŒrzlich identifizierten Polymorphismus im Gen der Rezeptortyrosinkinase FGFR4 (fibroblast growth factor receptor 4) im besonderen Hinblick auf seine ZusammenhĂ€nge mit der humanen Tumorpathogenese nĂ€her untersucht. Es handelt sich dabei um eine Keimbahnmutation, die zu einem Austausch der hydrophoben AminosĂ€ure Glycin gegen die hydrophile, stark geladene AminosĂ€ure Arginin an Position 388 (Arg388) und somit zu einer verĂ€nderten Proteinstruktur in der TransmembrandomĂ€ne des Rezeptors fĂŒhrt. Zuvor publizierte Studien, die Tumore verschiedener Organsysteme mit Fokus auf den FGFR4 Polymorphismus untersuchten, postulieren einen Zusammenhang zwischen der Rezeptormutation und seinem Einfluss auf die Tumorprogression und das Metastasierungspotential. Um diesen Einfluss der Mutation in unserem Tumorkollektiv zu untersuchen, fĂŒhrten wir bei Tumorproben von 301 Patienten, die an einem Plattenepithelkarzinom aus dem Bereich des Oropharynx litten, eine Genotypisierung mittels RFLP-PCR sowie immunhistochemische Untersuchungen durch, um die ExpressionsstĂ€rke des FGFR4 feststellen zu können. Dabei zeigte sich, dass der FGFR4 in 34% der FĂ€lle in heterozygoter oder homozygoter mutierter Form im Kollektiv vorliegt. Das entspricht einer Allelfrequenz fĂŒr das Arg388 von 0.2. Die Verteilung der Rezeptorexpression im Kollektiv war weitgehend gleichmĂ€ÎČig verteilt. Um die Auswirkungen der durch die Untersuchungen gewonnenen Parameter auf die Tumorpathogenese festzustellen, wurden sie mit einem umfassenden Datensatz, der aus den Patientenakten gewonnen wurde, korreliert.
Statistische Untersuchungen wiesen keine signifikanten ZusammenhĂ€nge zwischen dem FGFR4 Genotyp und der Tumorprogression oder einem gesteigertem Metastasierungspotential nach. Auch die in anderen Organsystemen zuvor festgestellte verringerte rezidivfreie Ăberlebenszeit bei Vorliegen des Arg388 Allels konnte in dem Kollektiv dieser Studie nicht reproduziert werden. BezĂŒglich der Rezeptorexpression ergaben unsere Untersuchungen Hinweise auf einen Ăberlebensvorteil bei starker FGFR4 Expression. Signifikante ZusammenhĂ€nge zwischen Rezeptorexpression und TumorgröÎČe oder Tumorprogression konnten jedoch nicht nachgewiesen werden und decken sich mit den Ergebnissen von Streit et al. Somit können wir die bereits mehrfach postulierte Perspektive nicht stĂ€rken, den FGFR4 als PrĂ€diktor oder prognostischen Parameter bei Krebserkrankungen zu deklarieren
A Time-Saving Approach to Parameter Studies in Microwave-Assisted Freeze Drying
Microwave-assisted freeze drying (MFD) is particularly suited for drying heat-sensitive materials. However, optimizing process parameters is time-consuming due to lengthy individual experiments. This study investigates the feasibility of partial MFD for parameter studies, with the process being terminated after removing 20 wt% of the water contained. The proposed approach reduces the time required for parameter evaluation by 92.0% compared to complete MFD. It also enables the evaluation of the samplesâ drying homogeneity. A subsequent parameter study based on partial MFD was then conducted to evaluate the effects of chamber pressure, microwave power, and microwave frequencies on the drying kinetics and drying homogeneity. Lowering the average chamber pressure from 0.87 mbar to 0.19 mbar reduced the process duration by 18.8%. An increase in the dissipated specific microwave power from 0.048 W/g to 0.143 W/g reduced the duration by 46.7%. The targeted application of frequencies increased the average energy efficiency to as high as 92.4%, contributing to a shortened process duration of up to 51.2%. Only the application of multiple frequencies caused a notable increase in drying homogeneity. In summary, this study demonstrates the feasibility and time-saving benefits of partial drying for parameter studies in MFD and potentially different types of drying processes
On the Transit Potential of the Planet Orbiting iota Draconis
Most of the known transiting exoplanets are in short-period orbits, largely
due to the bias inherent in detecting planets through the transit technique.
However, the eccentricity distribution of the known radial velocity planets
results in many of those planets having a non-negligible transit probability.
One such case is the massive planet orbiting the giant star iota Draconis, a
situation where both the orientation of the planet's eccentric orbit and the
size of the host star inflate the transit probability to a much higher value
than for a typical hot Jupiter. Here we present a revised fit of the radial
velocity data with new measurements and a photometric analysis of the stellar
variability. We provide a revised transit probability, an improved transit
ephemeris, and discuss the prospects for observing a transit of this planet
from both the ground and space.Comment: 6 pages, 7 figures, accepted for publication in ApJ. Radial
velocities will be made available in the on-line version and through the NASA
Star and Exoplanet Database (NStED). Minor corrections from ApJ proof have
been applie
Determinants of Physical Activity and Sedentary Behavior in German Elementary School Physical Education Lessons
Physical activity (PA) in school physical education (PE) is a signature component of health promotion and health education. The study's aim was to explore PA levels and sedentary time in German elementary school PE lessons and relate them to selected personal and environmental PA determinants. Accelerometer measurements were collected from 328 students (47% male, mean age 8.7 ± 1.2 years) in 11 elementary schools in Baden-Wuerttemberg (Germany). PA levels and sedentary time were analyzed regarding gender, grade, body mass index, selected correlates of active living and health behaviors, as well as the PE teachers' PE education status. In line with previous research, the analyses of PA levels and sedentary time confirm gender and grade differences and highlight older girls as the less active group. Deviant weight status and parents' PA levels were found to be important determinants for PA levels and sedentary time of girls and offer starting points for intervention studies as well as gender-appropriate PE in elementary schools. Specialist PE teacher status proved to be a negative determinant of PA levels and sedentary time for boys and girls and should be investigated in further studies, especially regarding the didactic and methodological background
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