Wider cooperation with Iran would be in the EU’s strategic interest

Iran is currently in talks with the UK, France, Germany, Russia, China and the United States over the country’s nuclear programme, with the aim of reaching a framework for a comprehensive deal before the end of March. Cornelius Adebahr writes that while an agreement would be a major diplomatic achievement, the EU should look to go much further than the nuclear issue in its relations with the country. He argues that wider cooperation with Iran, where possible, would be in the EU’s long-term strategic interest

Non-destructive Testing of 3D-Hybrid Components Using Air-coupled Ultrasound

The increasing use of hybrid lightweight structures in the automotive industry brings new challenges in the area of multi-material boundaries. Insufficient bonding quality between two kinds of materials, especially in highly loaded structures, affects the component’s performance. Hence, it is very important to monitor the bonding quality in multi-material structures. Flat specimen, consisting of sheet steel and organic sheet layers were examined using air- coupled ultrasound transducers in reflection setup. By slanted incidence of the ultrasound on the profile’s surface, guided waves were excited in the specimen and delaminated areas could be visualized due to changed phase values in the received signal. Furthermore, a 3D-Hybrid cap profile consisting of sheet steel, organic sheet layers and injection molded reinforcing ribs was examined using a special transducer setup. Results show that distinctions in the received signal could be made between bonded and delaminated organic sheets as well as intact and broken ribs behind the organic sheet layer. Several frequencies from 200 kHz up to 500 kHz were then used and compared with this new setup. Simulations of the guided waves propagation support the findings

M82 - A radio continuum and polarisation study II. Polarisation and rotation measures

The composition and morphology of the interstellar medium in starburst galaxies has been well investigated, but the magnetic field properties are still uncertain. The nearby starburst galaxy M82 provides a unique opportunity to investigate the mechanisms leading to the amplification and reduction of turbulent and regular magnetic fields. Possible scenarios of the contribution of the magnetic field to the star-formation rate are evaluated. Archival data from the VLA and WSRT were combined and re-reduced to cover the wavelength regime between 3cm and 22cm. All observations revealed polarised emission in the inner part of the galaxy, while extended polarised emission up to a distance of 2kpc from the disk was only detected at 18cm and 22cm. The observations hint at a magnetised bar in the inner part of the galaxy. We calculate the mass inflow rate due to magnetic stress of the bar to 7.1 solar masses per year, which can be a significant contribution to the star-formation rate of M82 of approximately 13 solar masses per year. The halo shows polarised emission, which might be the remnant of a regular disk field. Indications for a helical field in the inner part of the outflow cone are provided. The coherence length of the magnetic field in the centre is similar to the size of giant molecular clouds. Using polarisation spectra more evidence for a close coupling of the ionised gas and the magnetic field as well as a two-phase magnetic field topology were found. Electron densities in the halo are similar to the ones found in the Milky Way. The magnetic field morphology is similar to the one in other nearby starburst galaxies with possible large-scale magnetic loops in the halo and a helical magnetic field inside the outflow cones. The special combination of a magnetic bar and a circumnuclear ring are able to significantly raise the star-formation rate in this galaxy by magnetic braking

M82 - A radio continuum and polarisation study I. Data reduction and cosmic ray propagation

The potential role of magnetic fields and cosmic ray propagation for feedback processes in the early Universe can be probed by studies of local starburst counterparts with an equivalent star-formation rate. Archival data from the WSRT was reduced and a new calibration technique introduced to reach the high dynamic ranges needed for the complex source morphology of M82. This data was combined with archival VLA data, yielding total power maps at 3cm, 6cm, 22cm and 92cm. The data shows a confinement of the emission at wavelengths of 3/6cm to the core region and a largely extended halo reaching up to 4kpc away from the galaxy midplane at wavelengths of 22/92cm up to a sensitivity limit of 90muJy and 1.8mJy respectively. The results are used to calculate the magnetic field strength in the core region to 98muG and to 24muG in the halo regions. From the observation of free-free losses the filling factor of the ionised medium could be estimated to 2%. We find that the radio emission from the core region is dominated by very dense HII-regions and supernova remnants, while the surrounding medium is filled with hot X-ray and neutral gas. Cosmic rays radiating at frequencies higher than 1.4 GHz are suffering from high synchrotron and inverse Compton losses in the core region and are not able to reach the halo. Even the cosmic rays radiating at longer wavelengths are only able to build up the observed kpc sized halo, when several starbursting periods are assumed where the photon field density varies by an order of magnitude. These findings together with the strong correlation between Halpha, PAH+, and our radio continuum data suggests a magnetic field which is frozen into the ionised medium and driven out of the galaxy kinematically.Comment: 17 pages, 17 figures, to be published in A&

Low-Frequency Spectral Turn-Overs in Millisecond Pulsars Studied from Imaging Observations

Measurements of pulsar flux densities are of great importance for understanding the pulsar emission mechanism and for predictions of pulsar survey yields and the pulsar population at large. Typically these flux densities are determined from phase-averaged "pulse profiles", but this method has limited applicability at low frequencies because the observed pulses can easily be spread out by interstellar effects like scattering or dispersion, leading to a non-pulsed continuum component that is necessarily ignored in this type of analysis. In particular for the class of the millisecond pulsars (MSPs) at frequencies below 200MHz, such interstellar effects can seriously compromise de- tectability and measured flux densities. In this paper we investigate MSP spectra based on a complementary approach, namely through investigation of archival con- tinuum imaging data. Even though these images lose sensitivity to pulsars since the on-pulse emission is averaged with off-pulse noise, they are insensitive to effects from scattering and provide a reliable way to determine the flux density and spectral indices of MSPs based on both pulsed and unpulsed components. Using the 74MHz VLSSr as well as the 325MHz WENSS and 1.4GHz NVSS catalogues, we investigate the imaging flux densities of MSPs and evaluate the likelihood of spectral turn-overs in this population. We determine three new MSP spectral indices and identify six new MSPs with likely spectral turn-overs.Comment: 10 pages, 4 figures, 3 tables, accepted for publication in MNRA

Wahlen ohne Wandel: das iranische Regime trotzt Wirtschaftskrise und Kriegsgefahr

"Von Revolution keine Spur. Wer gehofft hatte, die Wahlen zum iranischen Parlament, dem Majlis, könnten die Bevölkerung noch einmal in Aufruhr versetzen wie im Sommer 2009, sieht sich enttäuscht. Mit dem Ferienbeginn zum iranischen Neujahrsfest, das pünktlich zum Frühlingsanfang das ganze Land zum Erliegen bringt, hat das Regime eine weitere kritische Phase überstanden. Iran bleibt von einem nachgeholten »persischen« Frühling bzw. der Vollendung der vor knapp drei Jahren begonnenen Grünen (Oppositions-)Bewegung weit entfernt. Gleichwohl verschärfen die internationalen Sanktionen und die zunehmende Kriegsrhetorik die bestehende Wirtschaftskrise. Ob diese ökonomische Malaise letztlich zu einer Veränderung der Verhältnisse in Iran führen wird, ist eine – von Hoffnungen und Wünschen begleitete – offene Frage." [Autorenreferat