542 research outputs found
Fourier analysis of gapped time series: Improved estimates of solar and stellar oscillation parameters
No full textQuantitative helioseismology and asteroseismology require very precise measurements of the frequencies, amplitudes, and lifetimes of the global modes of stellar oscillation. The precision of these measurements depends on the total length (T), quality, and completeness of the observations. Except in a few simple cases, the effect of gaps in the data on measurement precision is poorly understood, in particular in Fourier space where the convolution of the observable with the observation window introduces correlations between different frequencies. Here we describe and implement a rather general method to retrieve maximum likelihood estimates of the oscillation parameters, taking into account the proper statistics of the observations. Our fitting method applies in complex Fourier space and exploits the phase information. We consider both solar-like stochastic oscillations and long-lived harmonic oscillations, plus random noise. Using numerical simulations, we demonstrate the existence of cases for which our improved fitting method is less biased and has a greater precision than when the frequency correlations are ignored. This is especially true of low signal-to-noise solar-like oscillations. For example, we discuss a case where the precision of the mode frequency estimate is increased by a factor of five, for a duty cycle of 15%. In the case of long-lived sinusoidal oscillations, a proper treatment of the frequency correlations does not provide any significant improvement; nevertheless, we confirm that the mode frequency can be measured from gapped data with a much better precision than the 1/T Rayleigh resolution
Identiteter och världsbild : "hårdkokt" skriftbruk i Thorsten Jonssons noveller
No full textidentity and worldview – “hard-boiled” writing in Thorsten Jonsson’s short storiesThis article deals with the Swedish author Thorsten Jonsson (1910–50) and his first short story collection Som det brukar vara (1939) [‘As it usually is’]. The nar- rative represents a new modernistic literary trend in Swedish prose in the 1930s. i take my starting point in Burgess & ivanič’s (2010) theories of the act of writing involving many different identities, and particularly what Burgess & ivanič iden- tify as the discursive self. By contemporary readers and critics the discursive self in the short story collection was often connected with an American hard-boiled literary ideal, often linked to ernest Hemingway’s writings. in this article i dis- cuss the common textual features of the two authors’ first collections, but also the differences that emerge when looking through the linguistic surface. The analysis shows that Thorsten Jonsson’s discursive self is based upon a northern Swedish culture, Hemingway’s on an urban American one. </p
Measures of excess liquidity
No full textThe aim of this note is to provide an overview of various measures of excess liquidity, which can be defined as the deviation of the actual stock of money from an estimated equilibrium level. Given their dynamic nature, the excess liquidity measures under review are - in the light of long and variable lags of monetary policy - very useful tools to quantify future price pressures. In addition, excess liquidity measures consider inflation as a purely monetary phenomenon: neither the output gap nor liquidity gap - although both form an integral part of the concepts - an be held responsible for inducing a persistent rise in the price level. Despite strong theoretical support, the usefulness of excess liquidity measures depends on the stability of money demand, a question which has of course to be answered in the realm of empirical research. --P-star,excess liquidity,monetary policy,ECB
A case for money in the ECB monetary policy strategy
No full textOne major outcome of the review of the ECBs two pillar monetary policy strategy, which was published on 8 May 2003, has been the de facto downgrading of the hitherto prominent role assigned to the stock of money. According to the authors judgement, however, there is a strong theoretical and empirical rationale for the ECB monetary policy to pay close attention to the information content of money in the form of M3. However, the authors argue the ECB should make use of the so-called price gap or real money gap concept rather than the reference value as the latter runs the risk of giving misleading policy recommendations and compromising the indicator quality of the stock of money. Making use of M3 seems all the more rational as currently no better inflation indicator appears to exist in providing inflation forecasts in the euro area. --P-star,real money gap,excess liquidity,ECB
SDSS J212531.92–010745.9 : the first definite PG 1159 close binary system
No full textAims. The archival spectrum of SDSS J212531.92−010745.9 shows not only the typical signature of a PG 1159 star, but also indicates the presence of a companion. Our aim was the proof of the binary nature of this object and the determination of its orbital period.
Methods. We performed time-series photometry of SDSS J212531.92−010745.9. We observed the object during 10 nights, spread over one month, with the Tübingen 80 cm and the Göttingen 50 cm telescopes. We fitted the observed light curve with a sine and simulated the light curve of this system with the nightfall program. Furthermore, we compared the spectrum of SDSS J212531.92−010745.9 with
NLTE models, the results of which also constrain the light curve solution.
Results. An orbital period of 6.95616(33) h with an amplitude of 0.354(3) mag is derived from our observations. A pulsation period could not be detected. For the PG 1159 star we found, as preliminary results from comparison with our NLTE models, T eff ∼ 90 000 K, log g ∼ 7.60, and the abundance ratio C/He ∼ 0.05 by number fraction. For the companion we obtained with a mean radius of 0.4 ± 0.1 R, a mass of 0.4 ± 0.1 M, and a temperature of 8200 K on the irradiated side, good agreement between the observed light curve and the nightfall simulation, but we do not regard those values as final
Why is unemployment so high in Bulgaria?
No full textThe author seeks to determine the main factors behind poor labor market outcomes in Bulgaria. Unemployment in Bulgaria is high and of long duration. The accumulation of the unemployment stock has been caused by relatively high inflows into unemployment coupled with limited outflows. These features of the Bulgarian labor market are typical of other transition economies in Central Europe and exploring their sources is of broad interest. The author focuses on determinants of and constraints to job creation. He uses data on job creation and job destruction from a survey of employment in all registered firms. He finds that the source of large inflows into unemployment is intensive enterprise restructuring associated with a high pace of job reallocation. However, job creation falls short of job destruction. Three main factors account for the limited job creation and hiring, and thus for low outflows from unemployment: a) The unfriendly business environment, reflected by a low rate of new firm formation, and a relatively small, small and medium enterprise sector. b) Labor market rigidities, including excessive hiring and firing costs. c) Skill and spatial mismatches brought about by enterprise restructuring, as well as low skills and marginalization of the long-term unemployed who cannot successfully compete for new jobs. The author recommends a three pronged strategy to improve labor market performance: (1) removing bureaucratic constraints to entry and expansion of firms; (2) enhancing labor market flexibility through lowering hiring and firing costs; and (3) improving the educational system so as to equip workers with broad and portable skills.Environmental Economics&Policies,Labor Policies,Labor Markets,Public Health Promotion,Health Monitoring&Evaluation,Environmental Economics&Policies,Labor Markets,Health Monitoring&Evaluation,Labor Standards,Banks&Banking Reform
Improvements to the Secure Construction and Utilization of Greedy Embeddings in Friend-to-Friend Overlays
No full textRouting based on greedy network embeddings enables efficient and privacy-preserving routing in overlays where connectivity is restricted to mutually trusted nodes. In previous works, we proposed security enhancements to the embedding and routing procedures to protect against denial-of-service attacks by malicious overlay participants. In this work, we propose an improved timeout scheme to reduce the stabilization overhead of secure tree maintenance in response to node failures and malicious behavior. Furthermore, we present an attack-resistant packet replication scheme that leverages alternative paths discovered during routing
Zeitreihenanalyse sonnenähnlicher Oszillationen Anwendung auf Beobachtungen der Sonne und HD52265
No full textDie Untersuchung von Schwingungen in Sternen erlaubt es, den inneren Aufbau und die Dynamik der Sterne mit einer Genauigkeit zu bestimmen, die mit keiner anderen Methode erreicht werden kann. Den Schwerpunkt der vorliegenden Dissertation bildet die Messung der Parameter (Frequenzen, Amplituden, Linienbreiten und rotationsbedingte Frequenzaufspaltung) der globalen Moden sonnenähnlicher Schwingungen, die in der Sonne und dem sonnenähnlichen Stern HD52265 beobachtet wurden. Die Arbeit ist in drei Hauptteile gegliedert: (i) Die Implementierung und Validierung eines globalen Fits stellarer Schwingungsspektren anhand von Sonnenbeobachtungen, (ii) die Anwendung dieser Methode auf eine viermonatige CoRoT-Beobachtung des sonnenähnlichen Sterns HD52265, der außerdem von einem Planeten umkreist wird, sowie (iii) die Erweiterung der Auswertungsmethode auf Zeitreihen mit Unterbrechungen. Die Hauptergebnisse meiner Arbeit betreffen HD52265: Die Schwingungsfrequenzen der Radial-, Dipol- und Quadrupolmoden wurden mit der höchsten, jemals für einen sonnenähnlichen Stern erreichten Genauigkeit gemessen. Zum ersten Mal konnte der Effekt der stellaren Rotation auf die Schwingungsmoden zweifelsfrei für einen sonnenähnlichen Stern nachgewiesen werden. Außerdem erlaubte uns die seismologische Messung der Neigung der Rotationsachse des Sterns, die absolute Masse des Begleiters abzuschätzen. Demzufolge legt die asteroseismologische Untersuchung nahe, dass es sich bei dem Begleiter um einen Planeten und nicht um einen Braunen Zwerg handelt.The study of stellar oscillations allows one to constrain the structure and dynamics of stellar interiors to a precision that cannot be achieved with other methods. This dissertation focusses on the measurements of the parameters (frequencies, amplitudes, linewidths, and rotational splitting) of the global modes of solar-like oscillations observed in the Sun and in the Sun-like star HD52265. The thesis is organized in three main parts: (i)~an implementation and validation of a global fit of stellar oscillation power spectra using solar observations, (ii) an application of this method to original 4-month-long CoRoT observations of the planet-hosting, solar-like star HD52265, and (iii) an extension of the fitting method to time series with gaps. The main results concern HD52265: the mode frequencies of the radial, dipole and quadrupole modes are measured with the highest precision achieved so far for a solar-type star and, for the first time, the effect of rotation on oscillations in a solar-type star are measured without a doubt. Furthermore, the seismic constraint on the inclination angle of the stellar rotation axis allows us to estimate the absolute mass of the companion. Accordingly the seismic analysis strongly suggests that the companion is a planet and not a brown dwarf
Living with Wolves
No full textWith their return to Germany, wolves leave their traces in personal feelings, in the atmospheres of rural landscapes and even in the sentiments and moods that govern political arenas. Thorsten Gieser explores the role of affects, emotions, moods and atmospheres in the emerging coexistence between humans and wolves. Bridging the gap between anthropology and ethology, the author literally walks in the tracks of wolves to follow their affective agency in a more-than-human society. In nuanced analyses, he shows how wolves move, irritate and excite us, offering answers to the primary question: What does it feel like to coexist with these large predators
Living with Wolves: Affects, Feelings and Sentiments in Human-Wolf-Coexistence
No full textWith their return to Germany, wolves leave their traces in personal feelings, in the atmospheres of rural landscapes and even in the sentiments and moods that govern political arenas. Thorsten Gieser explores the role of affects, emotions, moods and atmospheres in the emerging coexistence between humans and wolves. Bridging the gap between anthropology and ethology, the author literally walks in the tracks of wolves to follow their affective agency in a more-than-human society. In nuanced analyses, he shows how wolves move, irritate and excite us, offering answers to the primary question: What does it feel like to coexist with these large predators
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