Statistical properties and economic implications of Jump-Diffusion Processes with Shot-Noise effects

This paper analyzes the Shot-Noise Jump-Diffusion model of Altmann, Schmidt and Stute (2008), which introduces a new situation where the effects of the arrival of rare, shocking information to the financial markets may fade away in the long run. We analyze several economic implications of the model, providing an analytical expression for the process distribution. We also prove that certain specifications of this model can provide negative serial persistence. Additionally, we find that the degree of serial autocorrelation is related to the arrival and magnitude of abnormal information. Finally, a GMM framework is proposed to estimate the model parameters

Radiation hydrodynamics integrated in the code PLUTO

The transport of energy through radiation is very important in many astrophysical phenomena. In dynamical problems the time-dependent equations of radiation hydrodynamics have to be solved. We present a newly developed radiation-hydrodynamics module specifically designed for the versatile MHD code PLUTO. The solver is based on the flux-limited diffusion approximation in the two-temperature approach. All equations are solved in the co-moving frame in the frequency independent (grey) approximation. The hydrodynamics is solved by the different Godunov schemes implemented in PLUTO, and for the radiation transport we use a fully implicit scheme. The resulting system of linear equations is solved either using the successive over-relaxation (SOR) method (for testing purposes), or matrix solvers that are available in the PETSc library. We state in detail the methodology and describe several test cases in order to verify the correctness of our implementation. The solver works in standard coordinate systems, such as Cartesian, cylindrical and spherical, and also for non-equidistant grids. We have presented a new radiation-hydrodynamics solver coupled to the MHD-code \PLUTO that is a modern, versatile and efficient new module for treating complex radiation hydrodynamical problems in astrophysics. As test cases, either purely radiative situations, or full radiation-hydrodynamical setups (including radiative shocks and convection in accretion discs) have been studied successfully. The new module scales very well on parallel computers using MPI. For problems in star or planet formation, we have added the possibility of irradiation by a central source.Comment: 13 pages, 11 figures, accepted by Astronomy & Astrophysic

Detection of X-rays from the jet-driving Symbiotic Star MWC 560

We report the detection of X-ray emission from the jet-driving symbiotic star MWC 560. We observed MWC 560 with XMM-Newton for 36 ks. We fitted the spectra from the EPIC pn, MOS1 and MOS2 instruments with XSPEC and examined the light curves with the package XRONOS. The spectrum can be fitted with a highly absorbed hard X-ray component from an optically-thin hot plasma, a Gaussian emission line with an energy of 6.1 keV and a less absorbed soft thermal component. The best fit is obtained with a model in which the hot component is produced by optically thin thermal emission from an isobaric cooling flow with a maximum temperature of 61 keV, which might be created inside an optically-thin boundary layer on the surface of the accreting with dwarf. The derived parameters of the hard component detected in MWC 560 are in good agreement with similar objects as CH Cyg, SS7317, RT Cru and T CrB, which all form a new sub-class of symbiotic stars emitting hard X-rays. Our previous numerical simulations of the jet in MWC 560 showed that it should produce detectable soft X-ray emission. We infer a temperature of 0.17 keV for the observed soft component, i.e. less than expected from our models. The total soft X-ray flux (i.e. at < 3 keV) is more than a factor 100 less than predicted for the propagating jet soon after its birth (<0.3 yr), but consistent with the value expected due its decrease with age. The ROSAT upper limit is also consistent with such a decrease. We find aperiodic or quasi-periodic variability on timescales of minutes and hours, but no periodic rapid variability. All results are consistent with an accreting white dwarf powering the X-ray emission and the existence of an optically-thin boundary layer around it.Comment: 8 pages, 5 figure, accepted for publication in A &

Androgenisierung

Zusammenfassung: Hirsutismus, androgenetische Alopezie und Akne als Zeichen der Androgenisierung zählen zu den häufigsten Gründen für ambulante gynäkologische Konsultationen. Das diagnostisch-therapeutische Vorgehen richtet sich nach dem Schweregrad und der Progression der Symptomentwicklung. Die Beurteilung der Therapiewirksamkeit erfordert meist Geduld. Eine Zusammenarbeit zwischen Gynäkologie und Dermatologie ist häufig sinnvoll. Der Fokus dieses Beitrags liegt auf der Androgenisierung während der reproduktiven Lebensphase. Etwaige Besonderheiten in der Postmenopause werden hervorgehoben. Eine Androgenisierung vor der Pubertät, bei Kinderwunsch und in der Schwangerschaft wird nicht berücksichtig

Are jets in symbiotic stars driven by magnetic fields?

We compare two scenarios to launch jets -- formation by MHD processes or formation by thermal pressure in the boundary layer (BL) -- with respect to their compatibility with observational data of jets in symbiotic stars, especially in the well studied jet source MWC 560. Finally, we discuss points of further research to be done.Comment: 4 pages, accepted for publication in A & A Letter

Herzfrequenzvariabilität in der Postmenopause

Zusammenfassung: Autonomes Nervensystem und Herzfrequenzvariabilität: Sowohl eine Dysregulation des autonomen Nervensystems (ANS) als auch die Menopause sind mit einem erhöhten kardiovaskulären Risiko verbunden. Das kardiale ANS kann anhand der Herzfrequenzvariabilität (HRV) beurteilt und in Frequenzspektren aufgespalten werden, die sich dem Parasympathikus- und/oder Sympathikuseinfluss zuordnen lassen. Einfluss der endokrinen Lebensphasen: Bereits während des Menstruationszyklus zeigt sich eine zyklusabhängige Fluktuation der HRV. Mit dem menopausalen Östrogenabfall ist ein Anstieg des Sympathikotonus mit HRV-Reduktion verbunden, was mit einem erhöhten kardiovaskulären Risiko einhergeht. Das mit menopausalen Hitzewallungen verbundene erhöhte kardiovaskuläre Erkrankungsrisiko ist möglicherweise ebenso auf eine Sympathikusaktivierung zurückzuführen. Therapie: Eine Hormonersatztherapie vermag eventuell eine Wiederherstellung der autonomen Balance herbeizuführe

Implications of the non-detection of X-ray emission from HD 149427

HD 149427 is a very enigmatic object. It has been classified either as a planetary nebula or as a D'-type symbiotic star. Its distance is also highly uncertain. Furthermore, HD 149427 is a potential jet source. We report the non-detection of X-ray emission from HD 149427 and explore the implications to its nature. We observed the object with XMM-Newton with an effective exposure time of 33.5 ks. The upper limit for the flux of the X-ray emission in the soft band (2 keV) it is about 10^-14 erg/s/cm^2. We discuss the implication of our results in light of the possible natures of HD 149427 -- being a planetary nebula or a symbiotic star, close or very distant. The derived upper limits on the mass accretion rate of the white dwarf are untypical for symbiotic stars and may favor the picture of HD 149427 being a young PN. HD 149427 might be a symbiotic star in hibernation -- if a symbiotic star at all. We estimate the possible mass-loss rate and kinetic luminosity of the jet and find no contradiction with our upper limit of soft X-ray emission. Therefore the jet may be still present but it was too faint to be detected via soft X-ray emission.Comment: 11 pages, 4 figures, accepted for publication in IBV

Statistical properties of groundwater noble gas paleoclimate models: Are they robust and unbiased estimators?

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95652/1/ggge1627.pd