Search

Diffuse gamma-ray emission from the decay of radioactive $^{26}$Al is a messenger from the nucleosynthesis activity in our current-day galaxy. Because this material is attributed to ejections from massive stars and their supernovae, the gamma-ray signal includes information about nucleosynthesis in massive star interiors as it varies with evolutionary stages, and about their feedback on the surrounding interstellar medium. Our method of population synthesis of massive-star groups has been refined as a diagnostic tool for this purpose. It allows to build a bottom-up prediction of the diffuse gamma-ray sky when known massive star group distributions and theoretical models of stellar evolution and core-collapse supernova explosions are employed. We find general consistency of an origin in such massive-star groups, in particular we also find support for the clumpy distribution of such source regions across the Galaxy, and characteristics of large cavities around these. A discrepancy in the integrated $^{26}$Al gamma-ray flux is interpreted as an indication for excess $^{26}$Al emission from nearby, distributed in cavities that extend over major regions of the sky., 6 pages, 2 figures. Invited contribution to conference 'Nuclear Physics in Astrophysics X', Geneva Sep 2022

Reticulum II (Ret II) is a satellite galaxy of the Milky Way and presents a prime target to investigate the nature of dark matter (DM) because of its high mass-to-light ratio. We evaluate a dedicated INTEGRAL observation campaign data set to obtain $\gamma$-ray fluxes from Ret II and compare those with expectations from DM. Ret II is not detected in the $\gamma$-ray band 25--8000 keV, and we derive a flux limit of $\lesssim 10^{-8}\,\mathrm{erg\,cm^{-2}\,s^{-1}}$. The previously reported 511 keV line is not seen, and we find a flux limit of $\lesssim 1.7 \times 10^{-4}\,\mathrm{ph\,cm^{-2}\,s^{-1}}$. We construct spectral models for primordial black hole (PBH) evaporation and annihilation/decay of particle DM, and subsequent annihilation of positrons produced in these processes. We exclude that the totality of DM in Ret II is made of a monochromatic distribution of PBHs of masses $\lesssim 8 \times 10^{15}\,\mathrm{g}$. Our limits on the velocity-averaged DM annihilation cross section into $e^+e^-$ are $\langle \sigma v \rangle \lesssim 5 \times 10^{-28} \left(m_{\rm DM} / \mathrm{MeV} \right)^{2.5}\,\mathrm{cm^3\,s^{-1}}$. We conclude that analysing isolated targets in the MeV $\gamma$-ray band can set strong bounds on DM properties without multi-year data sets of the entire Milky Way, and encourage follow-up observations of Ret II and other dwarf galaxies., Comment: 8 pages, 10 figures, submitted

Star clusters are fundamental units of stellar feedback and unique tracers of their host galactic properties. In this review, we will first focus on their constituents, i.e. detailed insight into their stellar populations and their surrounding ionised, warm, neutral, and molecular gas. We, then, move beyond the Local Group to review star cluster populations at various evolutionary stages, and in diverse galactic environmental conditions accessible in the local Universe. At high redshift, where conditions for cluster formation and evolution are more extreme, we are only able to observe the integrated light of a handful of objects that we believe will become globular clusters. We therefore discuss how numerical and analytical methods, informed by the observed properties of cluster populations in the local Universe, are used to develop sophisticated simulations potentially capable of disentangling the genetic map of galaxy formation and assembly that is carried by globular cluster populations. Open access funding provided by Stockholm University. We thank the anonymous referee for a constructive and careful revision of this work. We thank the staff at ISSI for their generous hospitality, and the editors to invite us to contribute to this topic collection. We are grateful to Hui Li and Joel Pfeffer for sharing their data and Nate Bastian for providing comments on the manuscript. A.A. thanks Matteo Messa, Katie Hollyhead and the LEGUS and HiPEEC teams for support with the analyses showed in this review. A.A. acknowledges the support of the Swedish Research Council, Vetenskapsrådet, and the Swedish National Space Agency (SNSA). P.Z. acknowledges support by the Forschungsstipendium (grant number ZE 1159/1-1) of the German Research Foundation (DFG). J.M.D.K. and M.C. gratefully acknowledge funding from the German Research Foundation (DFG) in the form of an Emmy Noether Research Group (grant number KR4801/1-1) and a DFG Sachbeihilfe Grant (grant number KR4801/2-1). J.M.D.K. gratefully acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme via the ERC Starting Grant MUSTANG (grant agreement number 714907), and from Sonderforschungsbereich SFB 881 “The Milky Way System” (subproject B2) of the DFG. C.C.acknowledges funding from the Swiss National Foundation (SNF grants 200021_169125 and 200020_192039).

INTEGRAL/SPI is a space-based coded mask telescope featuring a 19-element Germanium detector array for high-resolution gamma-ray spectroscopy, encapsulated in a scintillation detector assembly that provide a veto for background from charged particles. In space, cosmic rays irradiate spacecraft and instrument, which results in a large instrumental background from activation of those materials, and leads to deterioration of the charge collection properties of the Ge detectors. We use 13.5 years of INTEGRAL/SPI spectra for each detector and for each pointing of the satellite. Spectral fits provide us with details about separated background components. From the strongest background lines, we first determine how the spectral response changes with time. We then determine how the instrumental background components change in intensities and other characteristics, most-importantly their relative distribution among detectors. Spectral resolution of Ge detectors in space degrades with time, up to 15% within half a year, consistently for all detectors, and across the SPI energy range. Semi-annual annealing operations recover these losses, yet there is a small long-term degradation. The intensity of instrumental background varies anti-correlated to solar activity, in general. There are significant differences among different lines and with respect to continuum. Background lines are found to have a characteristic, well-defined and long-term consistent intensity ratio among detectors. We use this to categorise lines in groups of similar behaviour. The dataset of spectral-response and background parameters as fitted across the INTEGRAL mission allows studies of SPI spectral response and background behaviour in a broad perspective, and efficiently supports precision modelling of instrumental background., 30 pages, including 18 figures and an extended table of gamma-ray lines. Accepted for publication in Astronomy and Astrophysics

International audience; Ticagrelor may be a more effective antiplatelet therapy than aspirin for the prevention of recurrent stroke and cardiovascular events in patients with acute cerebral ischemia.; We conducted an international double-blind, controlled trial in 674 centers in 33 countries, in which 13,199 patients with a nonsevere ischemic stroke or high-risk transient ischemic attack who had not received intravenous or intraarterial thrombolysis and were not considered to have had a cardioembolic stroke were randomly assigned within 24 hours after symptom onset, in a 1:1 ratio, to receive either ticagrelor (180 mg loading dose on day 1 followed by 90 mg twice daily for days 2 through 90) or aspirin (300 mg on day 1 followed by 100 mg daily for days 2 through 90). The primary end point was the time to the occurrence of stroke, myocardial infarction, or death within 90 days.; During the 90 days of treatment, a primary end-point event occurred in 442 of the 6589 patients (6.7%) treated with ticagrelor, versus 497 of the 6610 patients (7.5%) treated with aspirin (hazard ratio, 0.89; 95% confidence interval [CI], 0.78 to 1.01; P=0.07). Ischemic stroke occurred in 385 patients (5.8%) treated with ticagrelor and in 441 patients (6.7%) treated with aspirin (hazard ratio, 0.87; 95% CI, 0.76 to 1.00). Major bleeding occurred in 0.5% of patients treated with ticagrelor and in 0.6% of patients treated with aspirin, intracranial hemorrhage in 0.2% and 0.3%, respectively, and fatal bleeding in 0.1% and 0.1%.; In our trial involving patients with acute ischemic stroke or transient ischemic attack, ticagrelor was not found to be superior to aspirin in reducing the rate of stroke, myocardial infarction, or death at 90 days. (Funded by AstraZeneca; ClinicalTrials.gov number, NCT01994720.).

Type-Ia supernovae result from binary systems that include a carbon-oxygen white dwarf, and these thermonuclear explosions typically produce 0.5 M_solar of radioactive 56Ni. The 56Ni is commonly believed to be buried deeply in the expanding supernova cloud. Surprisingly, in SN2014J we detected the lines at 158 and 812 keV from 56Ni decay (��~8.8 days) earlier than the expected several-week time scale, only ~20 days after the explosion, and with flux levels corresponding to roughly 10% of the total expected amount of 56Ni. Some mechanism must break the spherical symmetry of the supernova, and at the same time create a major amount of 56Ni at the outskirts. A plausible explanation is that a belt of helium from the companion star is accreted by the white dwarf, where this material explodes and then triggers the supernova event., 7 pages, 3 figures; submitted 10 Apr 2014; accepted 21 Jul 2014 (www.sciencemag.org)

We study the evolution of isolated and merging interstellar bubbles of three stars (25, 32 and 60 M\odot) in a homogeneous background medium with a density of 10 mp /ccm via 3D-hydrodynamic simulations with standard ISM thermodynamics (optically thin radiative cooling and photo-electric heating) and time dependent energy and mass input according to stellar evolutionary tracks. We vary the position of the three stars relative to each other to compare the energy response for cases of isolated, merging and initially cospatial bubbles. Due to mainly the Vishniac instability, our simulated bubbles develop thick shells and filamentary internal structures in column density. The shell widths reach tens of per cent of the outer bubble radius, which compares favourably to observations. More energy is retained in the ISM for more closely packed groups, by up to a factor of three and typically a factor of two for intermediate times after the first supernova. Once the superbubble is established, different positions of the contained stars make only a minor difference to the energy tracks. For our case of three massive stars, the energy deposition varies only very little for distances up to about 30 pc between the stars. Energy injected by supernovae is entirely dissipated in a superbubble on a timescale of about 1 Myr, which increases slightly with the superbubble size at the time of the explosion. The Vishniac instability may be responsible for the broadening of the shells of interstellar bubbles. Massive star winds are significant energetically due to their - in the long run - more efficient, steady energy injection and because they evacuate the space around the massive stars. For larger scale simulations, the feedback effect of close groups of stars or clusters may be subsumed into one effective energy input with insignificant loss of energy accuracy., 14 pages, 15 figures, accepted by A&A, shortened, different code test

We investigate the evolution of dusty gas clouds falling into the centre of an active Seyfert nucleus. Two-dimensional high-resolution radiation hydrodynamics simulations are performed to study the fate of single clouds and the interaction between two clouds approaching the Active Galactic Nucleus. We find three distinct phases of the evolution of the cloud: (i) formation of a lenticular shape with dense inner rim caused by the interaction of gravity and radiation pressure (the lense phase), (ii) formation of a clumpy sickle-shaped structure as the result of a converging flow (the clumpy sickle phase) and (iii) a filamentary phase caused by a rapidly varying optical depth along the sickle. Depending on the column density of the cloud, it will either be pushed outwards or its central (highest column density) parts move inwards, while there is always some material pushed outwards by radiation pressure effects. The general dynamical evolution of the cloud can approximately be described by a simple analytical model., Comment: 13 pages, 18 figures, accepted by MNRAS

Radio observations of Fanaroff-Riley class II sources often show correlations between the synchrotron emission and the linear-polarimetric distributions. Magnetic position vectors seem to align with the projected emission of both the radio jets and the sources' edges. Using statistics we study such relation as well as its unknown time evolution via synthetic polarisation maps of model FR II sources formed in 3D-MHD numerical simulations of bipolar, hypersonic and weakly magnetised jets. The magnetic field is initially random with a Kolmogorov power spectrum, everywhere. We investigate the structure and evolution of magnetic fields in the sources as a function of the power of jets and the observational viewing angle. Our synthetic polarisation maps agree with observations, showing B-field vectors which are predominantly aligned with the jet axis, and show that magnetic fields inside sources are shaped by the jets' backflow. Polarimetry is found to correlate with time, the viewing angle and the jet-to-ambient density contrast. The magnetic structure inside thin elongated sources is more uniform than inside more spherical ones. We see jets increase the magnetic energy in cocoons in proportion to the jet velocity and the cocoon width. Filaments in the synthetic emission maps suggest turbulence develops in evolved sources., Comment: Accepted for publication in the MNRAS. 21 pages, 11 figures

We investigate the global dynamic stability of spherical clouds in the Broad Line Region (BLR) of Active Galactic Nuclei (AGN), exposed to radial radiation pressure, gravity of the central black hole (BH), and centrifugal forces assuming the clouds adapt their size according to the local pressure. We consider both, isotropic and anisotropic light sources. In both cases, stable orbits exist also for very sub-Keplerian rotation for which the radiation pressure contributes substantially to the force budget. We demonstrate that highly eccentric, very sub-Keplerian stable orbits may be found. This gives further support for the model of Marconi et al. 2008, who pointed out that black hole masses might be significantly underestimated if radiation pressure is neglected. That model improved the agreement between black hole masses derived in certain active galaxies based on BLR dynamics, and black hole masses derived by other means in other galaxies by inclusion of a luminosity dependent term. For anisotropic illumination, energy is conserved for averages over long time intervals, only, but not for individual orbits. This leads to Rosetta orbits that are systematically less extended in the direction of maximum radiation force. Initially isotropic relatively low column density systems would therefore turn into a disk when an anisotropic AGN is switched on., Comment: 7 pages, 4 fig.s, accepted by MNRAS, some text was missing - corrected

The aim of the study was to investigate the efficacy of the antibiotic minocycline as a drug treatment in patients with Multiple-System-Atrophy Parkinson-type (MSA-P). Sixty-three patients were randomized to minocycline 200 mg/d (n = 32) or a matching placebo (n = 31). The primary outcome variable was the change in the value of the motor score of the Unified Multiple-System-Atrophy Rating-Scale (UMSARSII) from baseline to 48 weeks. Secondary outcome variables included subscores and individual Parkinsonian symptoms as determined by the UMSARS and the Unified-Parkinson's-Disease Rating-Scale (UPDRS). Health-related quality of life (HrQoL) was assessed using the EQ-5D and SF-12. "Progression rate" was assumed to be reflected in the change in motor function over 48 weeks. At 24 weeks and 48 weeks of follow-up, there was a significant deterioration in motor scores in both groups, but neither the change in UMSARSII nor in UPDRSIII differed significantly between treatment groups, i.e. "progression rate" was considered to be similar in both treatment arms. HrQoL did not differ among the two treatment arms. In a small subgroup of patients (n = 8; minocycline = 3, placebo = 5)[(11)C](R)-PK11195-PET was performed. The three patients in the minocycline group had an attenuated mean increase in microglial activation as compared to the placebo group (P = 0.07) and in two of them individually showed decreased [11C](R)-PK11195 binding actually decreased. These preliminary PET-data suggest that minocycline may interfere with microglial activation. The relevance of this observation requires further investigation. This prospective, 48 week, randomized, double-blind, multinational study failed to show a clinical effect of minocycline on symptom severity as assessed by clinical motor function.

At high redshift, extragalactic jets are associated with extended emission line regions. We present global and local hydrodynamic simulations of the interaction of jets with their environment relevant to this phenomenon. We determine the fraction of kinetic energy and momentum of the jet that should appear in the emission line gas. From momentum considerations, we argue that the gas seen in outward motion in many examples must to a large part originate from within the galaxy. The host galaxies should have been massive, gas rich and heavily star forming galaxies. The expelled gas is not expected to return to the galaxy quickly. The observed kinetic energy in the emission line gas constrains the jet powers to be greater than 10^47 erg/s., Comment: 12 pages, 5 figures

A comparison is drawn between jet propagation in molecular clouds and jets launched by galaxies in clusters. The biggest difference between the two types of jets is found in the density contrast. While the cocoon plasma in extragalactic jets has now been detected in X-rays, the corresponding cocoon gas for Herbig-Haro flows is barely visible.

We report two simulations that have been carried out at the SX-5 at HLRS (Stuttgart). One simulation is axisymmetric and purely hydrodynamic, but with a resolution of 20 points per beam-radius (ppb). The bipolar jet is injected in the center of a spherically symmetric King profile, initially underdense to its environment by a factor of 10,000. As expected from our previous work, the jet starts with producing a spherical bubble around it, bounded by the bow shock. The bubble slowly elongates, first with roughly elliptical shape, and then forms narrower extensions in beam direction. The final aspect ratio of the bow shock is 1.8. We have transformed the results on a 3D-rectangular grid and integrated the emission properties to compare the results with observed central cluster radio galaxies. In the particular case of Cygnus A, we come to convincing consistency, morphologically, regarding the size of the influenced region by the jet, size, and cylindrical shape of the radio cocoon, and source age. This strongly supports our earlier hypothesis on the nature of the jet in Cygnus A, and the derived constraints on other jet parameters like a power of $8 \times 10^{46}$ erg/s and an age of 27 Myr. But, the simulation also clearly shows the shortcoming of the model: The jet's beam is very unstable, reaching the tip of the bow shock only very seldom. Also, the contact discontinuity between shocked beam plasma and shocked ambient gas is quite disrupted by the action of the Kelvin-Helmholtz-instability. This is not seen in observations, and necessitates the presence of dynamically important magnetic fields or an at least moderately relativistic flow, or both. [abridged], Comment: accepted for publication in the transactions of the HLRS 2003, Springer lecture notes Replacement due to a few minor orthographic mistakes

Background: Rapid alteplase delivery for ischemic stroke patients has been shown to increase the likelihood of disability-free life. Identification of barriers to rapid alteplase delivery and streamlining processes around imaging assessments are important. Our aim was to examine the relationships between hospital arrival time and post- imaging processes in stroke thrombolysis. Methods: De-identified data of patients who underwent intravenous alteplase therapy at 20 hospitals in Australia were entered into the Thrombolysis ImPlementation in Stroke (TIPS) audit tool. During the pre-intervention phase, 601 patients who received alteplase = 270 minutes of stroke onset were analysed. Onset-to-door (OTD), door-to-needle (DTN), door-to-imaging (DTI), and imaging-to-needle (ITN) times were assessed using univariable and multivariable linear regression analyses. Results: The age was 71.3 ± 13.4years, and the median NIHSS score was 11. The median OTD, DTN, DTI, ITN times were 73, 85, 32, and 46 minutes, respectively. Every minute earlier of OTD resulted in 0.24 minutes slower DTN (p

In den letzten Jahren ist die Entwicklung des Ultraschallecho-Verfahrens für die Anwendung in der zerstörungsfreien Prüfung im Bauwesen (ZfPBau) enorm vorangeschritten. Mittlerweile ist das Verfahren bei der Untersuchung von Stahlbetonbauteilen zu einem der vielversprechendsten für die Lösung komplexer Aufgaben herangereift. Automatisierbare Systeme und verbesserte manuelle Messgeräte haben zusammen mit der Entwicklung fortschrittlicher Software die Datenaufnahme und -bewertung erheblich beschleunigt. Die Methode der grafischen Phasenbewertung schließlich erlaubt auch die qualitative Unterscheidung von Einbauteilen. Die vorliegende Arbeit entstand an der Bundesanstalt für Materialforschung und -prüfung (BAM) am Fachbereich von Herrn Dr. Wiggenhauser und beschreibt die praktische Anwendung des Ultraschallecho-Verfahrens bei der Untersuchung von Spannbetonkonstruktionen, insbesondere zur Untersuchung des Verpresszustands von Hüllrohren. In enger Zusammenarbeit mit der BAM wurden an der Universität Kassel theoretische Ansätze zur Simulation der Ultraschallausbreitung in Spannbetonkonstruktionen verfolgt und die Software entwickelt, mit der die bildgebenden Darstellungen in der vorliegenden Arbeit erzeugt wurden. Anhand von Laborprobekörpern mit Referenzzuständen (leere und mörtelgefüllte Hüllrohre ohne Spannlitzen) konnte die grundsätzliche Eignung der grafischen Phasenbewertung für die Bewertung von Reflexion aus dem Hüllrohrinnern belegt werden. Weitere Messungen an realistischeren Hüllrohrquerschnitten brachten komplexe Resultate, die im Abgleich untereinander und mit den Referenzmessungen zum größten Teil gut nachvollzogen werden konnten. Es zeigte sich, dass die Interpretierbarkeit von Anzeigen aus dem Hüllrohr, die von Reflektoren jenseits der Spannlitzen kommen, erheblich von der Lage der Litzen im Hüllrohr abhängen können. Vergleichende Simulationen bestätigten diese Erkenntnisse. An einer großformatigen Testwand wurden umfangreiche Untersuchungen an weiteren vorgefertigten Hüllrohrabschnitten - zum Teil mehrlagig eingebaut - sowie an realitätsgetreu vorgespannten Spanngliedern durchgeführt, eingebaut jeweils hinter unterschiedlich dichter schlaffer Bewehrung. Dabei erwies sich die Qualität der Verdichtung des Betons als wesentliche Einflussgröße auf die Interpretierbarkeit von Messdaten, wohingegen der Einfluss des Bewehrungsgrads als nachrangig festgestellt wurde. An allen Probekörperserien wurden Untersuchungen zur Zustandsverifizierung durchgeführt. Einzelne vorgefertigte Hüllrohrabschnitte wurden per Vakuuminjektion mit Verpressharz konserviert, um nach dem Aufschneiden den Erfolg des im Labor weitgehend drucklosen Befüllens mit Einpressmörtel überprüfen zu können. Weitere laborgefertigte Hüllrohre wurden per Radiographie und Computertomografie begutachtet. An der Testwand wurden umfangreiche Durchstrahlungsprüfungen durchgeführt, um insbesondere an den realistisch vorgespannten Spanngliedern Litzenlage und Verpresserfolg nachzuvollziehen. Mit diesem Verfahren konnten in der 50 cm breiten Wand einzelne Spannlitzen in Hüllrohren identifiziert werden sowie an einem unbeabsichtigt aufgeschwommenen Hüllrohr ein geometrisch bedingter Verpressfehler nachgewiesen werden. Die Relevanz für die Praxis wird anhand von drei unterschiedlichen Anwendungen aufgezeigt: An einer neu erbauten Brücke waren Lage und Abmessungen eines bei der Herstellung eines Brückensegments aufgetretenen Hüllrohrverstopfers zu lokalisieren. An einer per externer Vorspannung zu verstärkenden Spannbetonbrücke in Plattenbalkenbauweise waren für schadfreies Bohren im Bereich der Endverankerungen sämtliche Hüllrohre im Balken in großer Tiefe und hinter starker Bewehrung exakt zu lokalisieren. Für die Detektion von Fehlstellen in stahlplattenummanteltem Beton war unter Einsatz der bildgebenden Phasenauswertung die praktische Grundlagenarbeit zu erbringen, um den Einfluss der Stahlplatten auf die Messdaten einschätzen zu können. Abschließend werden die mit den Ergebnissen dieser Arbeit gegenwärtig erreichten Möglichkeiten und Grenzen der Anwendung des Ultraschallechoverfahrens bei der Untersuchung von Spannbetonkonstruktionen und bei Einsatz der bildgebenden Phasenauswertung zusammengefasst sowie der Forschungsbedarf für eine Weiterentwicklung der Verfahren beschrieben., In recent years, a vast improvement has been made in the field of non-destructive testing in civil engineering (NDT CE) using the ultrasound echo method. Meanwhile, this technique has become one of the most powerful approaches for solving complex issues when examining concrete members. Automated scanning systems, improved devices for manual handling and progressive reconstruction software for showing images of results allow quicker investigation and evaluation than ever before. Lately, imaging phase evaluation made it possible to not only detect, but also graphically distinguish and characterize built-in components. The present thesis was developed at Federal Institute for Materials Research and Testing (BAM) in Berlin in the group of Dr. Wiggenhauser, with the aim to improve the practical application of the ultrasonic echo method to pre-stressed concrete, with special attention to the evaluation of the grouting condition of tendon ducts. Theoretical approaches were pursued at University of Kassel in close collaboration with BAM, especially the simulation and the reconstruction of ultrasonic wave propagation in pre-stressed concrete, along with the development of specific imaging software used in the present work. Laboratory specimens were constructed to prove the fundamental suitability of the imaging phase evaluation approach for the evaluation of the grouting condition of ducts. This was achieved by measurements at reference specimens without steel strands inside the ducts. Further measurements at more realistic ducts with strands showed complex results which could, for the most part, be understood in comparison with each other and the reference measurements. It became apparent that the visibility of reflectors lying beyond the strands is complicated, strongly depending on the strands’ arrangement inside the duct. Comparative simulations supported these findings. At a large test wall, advanced comprehensive studies were carried out on additional pre-fabricated ducts, partly in multiple layers, and real pre-stressed ducts manufactured according to official guidelines, mounted behind the reinforcement of varying density. Here, the quality of concrete compaction played a vital role for the interpretability of data, while the reinforment’s density turned out to be of lesser importance. Studies were carried out on several specimens to verify the location of the duct and its grouting condition. Individual pre-fabricated ducts were vacuum-injected with liquid resin and cut into slices after hardening to verify the complete grouting of the whole cross section. Additional specimens were checked by radiographic CT scans. At the test wall, comprehensive radiographic examinations were carried out successfully, making it possible to distinguish individual strands inside ducts in the 50 cm thick wall. In a duct accidentally swollen in fresh concrete due to incorrect installation, a geometrically caused grouting fault was detected. Three examples show the practical benefit of the method: At a newly built bridge, the ultrasound echo method was used to detect a blockade in a duct caused by penetration of concrete at a damaged spot, and estimate its extent. For strengthening a pre-stressed motorway bridge, internal tendon ducts behind strong reinforcement had to be detected in broad T-beams at end anchorages. To detect voids in steel-cased concrete, the basic practical work was conducted to be able to estimate the influence of steel layers on ultrasound measurement data. In the conclusion, the present state-of-the-art of the imaging ultrasound echo method with phase evaluation for the investigation of pre-stressed concrete is described, and an outlook on research needs for further improvement of the method is given.