Laser-driven ion acceleration is well established using solid targets mainly in the target normal sheath acceleration regime. To follow the increasing repetition rate available on high-intensity lasers, the use of high-density gas targets has been explored in the past decade. When interacting with targets reaching densities close to the critical one, the laser pulse can trigger different acceleration mechanisms such as Collisionless Shock Acceleration (CSA) or hole boring. Particle-in-cell simulations using ideal target profiles show that CSA can accelerate a collimated, narrow energy spread and few hundreds of megaelectronvolts ion beam on the laser axis. Nevertheless, in real experiments, the laser will not only interact with an overcritical, thin plasma slab with sharp density gradients, but also with lower density regions surrounding the core of the gas jet, extending to several hundreds of micrometres. The interaction of the laser with these lower density wings will lead to nonlinear effects that will reduce the available energy to drive the shock in the high-density region of the target. Optically tailoring this target could mitigate that issue. Recent experiments conducted on different laser facilities aimed at testing several tailoring configurations. We first tested a scheme with a copropagating picosecond prepulse to create a lower density plasma channel to facilitate the propagation of the main pulse, while the second one was a transverse tailoring driven by nanosecond laser pulses to generate blast waves and form a high-density plasma slab. The main results will be presented here and the methods compared.

The high-energy/high-intensity laser facility PHELIX of the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany, has been in operation since 2008. Here, we review the current system performance, which is the result of continuous development and further improvement. Through its versatile frontend architecture, PHELIX can be operated in both long- and short-pulse modes, corresponding to ns-pulses with up to 1 kJ pulse energy and sub-ps, 200 J pulses, respectively. In the short-pulse mode, the excellent temporal contrast and the control over the wavefront make PHELIX an ideal driver for secondary sources of high-energy ions, neutrons, electrons and X-rays. The long-pulse mode is mainly used for plasma heating, which can then be probed by the heavy-ion beam of the linear accelerator of GSI. In addition, PHELIX can now be used to generate X-rays for studying exotic states of matter created by heavy-ion heating using the ion beam of the heavy-ion synchrotron of GSI.

This paper presents the development and experimental utilization of a synchronized off-harmonic laser system designed as a probe for ultra-intense laser–plasma interaction experiments. The system exhibits a novel seed-generation design, allowing for a variable pulse duration spanning over more than three orders of magnitude, from 3.45 picoseconds to 10 nanoseconds. This makes it suitable for various plasma diagnostics and visualization techniques. In a side-view configuration, the laser was employed for interferometry and streaked shadowgraphy of a laser-induced plasma while successfully suppressing the self-emission background of the laser–plasma interaction, resulting in a signal-to-self-emission ratio of 110 for this setup. These properties enable the probe to yield valuable insights into the plasma dynamics and interactions at the PHELIX facility and to be deployed at various laser facilities due to its easy-to-implement design.

In order to reach the highest intensities, modern laser systems use adaptive optics to control their beam quality. Ideally, the focal spot is optimized after the compression stage of the system in order to avoid spatio-temporal couplings. This also requires a wavefront sensor after the compressor, which should be able to measure the wavefront on-shot. At PHELIX, we have developed an ultra-compact post-compressor beam diagnostic due to strict space constraints, measuring the wavefront over the full aperture of 28 cm. This system features all-reflective imaging beam transport and a high dynamic range in order to measure the wavefront in alignment mode as well as on shot.

We present a study of laser-driven ion acceleration with micrometre and sub-micrometre thick targets, which focuses on the enhancement of the maximum proton energy and the total number of accelerated particles at the PHELIX facility. Using laser pulses with a nanosecond temporal contrast of up to $10^{-12}$ and an intensity of the order of $10^{20}~\text{W}/\text{cm}^{2}$, proton energies up to 93 MeV are achieved. Additionally, the conversion efficiency at $45^{\circ }$ incidence angle was increased when changing the laser polarization to p, enabling similar proton energies and particle numbers as in the case of normal incidence and s-polarization, but reducing the debris on the last focusing optic.

Negative computer attitude has been shown to be a possible co-variable in computerized examinations of psychiatric patients, affecting patient-computer interaction as well as reliability and validity of assessment (Weber et al. 2002, Acta Psychiatr.Scand., 105, 126-130).

It remains still uncertain if the psychological construct of computer attitude can be dependably measured in acute psychiatric inpatients or whether it is impeded by the effects of mental illness. For that reason a German translation of the Groningen Computer Attitude Scale (GCAS) was evaluated in 160 acute psychiatric inpatients under naturalistic conditions.

General test criteria (internal structure, item analysis, internal consistency, split half reliability) to a large extent corresponded to those formerly found in healthy subjects and psychiatric outpatients. The mean GCAS score was calculated as 56.2 ± 10.8 points and a significantly better computer attitude was found in male, better educated and younger patients. Some diverging correlation patterns were found in diagnostic subgroups, indicating a possible minor impact of mental disorder on computer attitude.

Overall, the GCAS was found to be a suitable instrument for measuring computer attitude in acute psychiatric inpatients. It should be used in identifying patients with a negative attitude to computers in order to ensure reliability and validity of computerized assessment.

We propose and demonstrate the use of random phase plates (RPPs) for high-energy sub-picosecond lasers. Contrarily to previous work related to nanosecond lasers, an RPP poses technical challenges with ultrashort-pulse lasers. Here, we implement the RPP near the beginning of the amplifier and image-relay it throughout the laser amplifier. With this, we obtain a uniform intensity distribution in the focus over an area 1600 times the diffraction limit. This method shows no significant drawbacks for the laser and it has been implemented at the PHELIX laser facility where it is now available for users.

The Saxonian Cretaceous Basin constitutes an important source of rare Late Cretaceous marine amniote fossils from Germany. It is also historically famous, having been documented in a series of monographic works published by the distinguished German palaeontologist Hanns Bruno Geinitz in the nineteenth century. The most productive rock units include the upper Cenomanian Dölzschen Formation and upper Turonian Strehlen and Weinböhla limestones (lower Strehlen Formation). A survey of curated specimens recovered from these deposits has now identified isolated teeth of probable polycotylid and elasmosaurid plesiosaurians, as well as several humeri that are referred to protostegid marine turtles. The Saxonian Cretaceous Basin formed a continuous epeiric seaway with the Bohemian Cretaceous Basin during late Cenomanian – Turonian time. A western connection to the North Sea Basin also existed via the North German and Münsterland Cretaceous basins. The Mesozoic marine amniote remains from these regions therefore record a coeval northern European fauna that was probably homogeneous across the northern peri-Tethyan margin during Late Cretaceous time.

A novel optical method is used to measure the high-frequency (up to 3 MHz) density fluctuations that precede transition to turbulence within a laminar boundary layer in a hypervelocity flow. This optical method, focused laser differential interferometry, enables measurements of short-wavelength, high-frequency disturbances that are impossible with conventional instrumentation such as pressure transducers or hot wires. In this work, the T5 reflected-shock tunnel is used to generate flows in air, nitrogen and carbon dioxide with speeds between 3.5 and $5~\text{km}~\text{s}^{-1}$ (Mach numbers between 4 and 6) over a 5° half-angle cone at zero angle of attack. Simultaneous measurements are made at two locations approximately midway along a generator of the 1-m-long cone. With increasing Reynolds number (unit values were between 2 and $5\times 10^{6}~\text{m}^{-1}$), density fluctuations are observed to grow in amplitude and transition from a single narrow band of frequencies consistent with the Mack or second mode of boundary-layer instability to bursts of large-amplitude and spectrally broad disturbances that appear to be precursors of turbulent spots. Disturbances that are sufficiently small in initial amplitude have a wavepacket-like signature and are observed to grow in amplitude between the upstream and downstream measurement locations. A cross-correlation analysis indicates propagation of wavepackets at speeds close to the edge velocity. The free stream flow created by the shock tunnel and the resulting boundary layer on the cone are computed, accounting for chemical and vibrational non-equilibrium processes. Using this base flow, local linear and parabolized stability (PSE) analyses are carried out and compared with the experimental results. Reasonable agreement is found between measured and predicted most unstable frequencies, with the greatest differences being approximately 15 %. The scaling of the observed frequency with the inverse of boundary-layer thickness and directly with the flow velocity are consistent with the characteristics of Mack’s second mode, as well as results of previous researchers on hypersonic boundary layers.

In this case-control study, we investigated the seroprevalence and molecular evidence of Chlamydia trachomatis and Waddlia chondrophila in ectopic pregnancies (EP) and uneventful control pregnancies in 343 women from Vietnam. Whereas presence of C. trachomatis IgG was strongly associated with EP [adjusted odds ratio (aOR) 5·41, 95% confidence interval (CI) 2·58–11·32], its DNA remained undetected in all tubal lesions. We confirmed an independent association between antibodies against Waddlia and previous miscarriage (aOR 1·87, 95% CI 1·02–3·42). Further investigations are needed to understand the clinical significance of Waddlia's high seroprevalence (25·9% in control pregnancies) in this urban population.

In Germany, mosasaur remains are very rare and only incompletely known. However, the earliest records date back to the 1830s, when tooth crowns were found in the chalk of the Isle of Rügen. A number of prominent figures in German palaeontology and geosciences of the 19th and 20th centuries focused on these remains, including, among others, Friedrich von Hagenow, Hermann von Meyer, Andreas Wagner, Hanns Bruno Geinitz and Josef Pompeckj. Most of these works were only short notes, given the scant material. However, the discovery of fragmentary cranial remains in Westphalia in 1908 led to a more comprehensive discussion, which is also of historical importance, as it illustrates the discussions on the highly controversial and radical universal phylogenetic theory proposed by Gustav Steinmann in 1908. This theory saw the existence of continuous lines of descent, evolving in parallel, and did not regard higher taxonomic units as monophyletic groups but as intermediate paraphyletic stages of evolution. In this idea, nearly all fossil taxa form part of these lineages, which extend into the present time, and natural extinction occurs very rarely, if ever. In Steinmann's concept, mosasaurs were not closely related to squamates but formed an intermediate member in a anagenetic chain from Triassic thalattosaurs to extant baleen whales. The newly found specimen led Josef Pompeckj to write a vehement rebuttal to Steinmann's theory, published in 1910, showing that his conclusions were conjectural and speculative, being based on convergence and not supported by scientific evidence. This particular specimen, housed in Göttingen, later also inspired a piece of palaeoart by Franz Roubal under the instructions of Othenio Abel.

With the exception of a vertebra from the Campanian of former East Prussia (now Russian Federation), and a possible vertebra from the Cenomanian of Dresden, Saxony, all datable material – today partly lost – originated from the northern part of present-day Germany and stratigraphically from the Campanian–Maastrichtian. The purported record from the Cenomanian of Bavaria (southeastern Germany) was most probably an error, based on Upper Jurassic crocodilian material.

Hypersonic flows involving two or more bodies travelling in close proximity to one another are encountered in several important situations. The present work seeks to explore one aspect of the resulting flow problem by investigating the forces experienced by a secondary body when it is within the domain of influence of a primary body travelling at hypersonic speeds.

An analytical methodology based on the blast wave analogy is developed and used to predict the secondary force coefficients for simple geometries in both two and three dimensions. When the secondary body is entirely inside the primary shocked region, the nature of the lateral force coefficient is found to depend strongly on the relative size of the two bodies. For two spheres, the methodology predicts that the secondary body will experience an exclusively attractive lateral force if the secondary diameter is larger than one-sixth of the primary diameter. The analytical results are compared with those from numerical simulations and reasonable agreement is observed if an appropriate normalization for the relative lateral displacement of the two bodies is used.

Results from a series of experiments in the T5 hypervelocity shock tunnel are also presented and compared with perfect-gas numerical simulations, with good agreement. A new force-measurement technique for short-duration hypersonic facilities, enabling the experimental simulation of the proximal bodies problem, is described. This technique provides two independent means of measurement, and the agreement observed between the two gives a further degree of confidence in the results obtained.

It is demonstrated experimentally that the influence of viscosity on the transition condition in pseudosteady flow is very significant. A mechanism is proposed for this effect, which explains the features of the observed behaviour. In particular, an experimental method of finding the inviscid transition condition, by extrapolation to infinite Reynolds number, gives excellent agreement with the calcwlatcd inviscid sonic criterion. It is thought that this provides the explanation for the usual persistence of regular reflection beyond the sonic: condition.

Experiments were conducted in the free-piston shock tube and shock tunnel with dissociating nitrogen and carbon dioxide, ionizing argon and frozen argon to measure the transition condition in pseudosteady and steady flow. The transition condition in the steady flow, in which the wall was eliminated by symmetry, agrees with the calculated von Neumann condition. In the real gases this calculation assumed thermo-dynamic equilibrium after the reflected shock. In the pseudosteady flow of reflexion from a wedge the measured transition angle lies on the Mach-reflexion side of the calculated detachment condition by an amount which may be explained in terms of the displacement effect of the boundary layer on the wedge surface. A single criterion based on the availability of a length scale at the reflexion point explains the difference between the pseudosteady and steady flow transition condition and predicts a hysteresis effect in the transition angle when the shock angle is varied during steady flow. No significant effects on the transition condition due to finite relaxation length could be detected. However, new experiments in which interesting relaxation effects should be evident are suggested.

Experimental results for dissociating nitrogen flow over a wedge, obtained in a free-piston shock tunnel, are described. Interferograms of the flow show clearly the curvature of the shock wave and the rise in fringe shift after the shock associated with the dissociation. It is shown that the shock curvature a t the tip of the wedge can be used to calculate the initial dissociation rate and that it is a more sensitive indication of the rate than can be obtained from fringe shift measurements under the prevailing experimental conditions. Because the free-stream dissociation fraction can be adjusted in the shock tunnel, the dependence on atomic nitrogen concentration of the dissociation rate can be determined by the shock curvature method. A detailed calculation of the flow field by an inverse method, starting from the measured shock shape, shows good agreement with experiments.

In this presentation the various technology steps for the monolithic integration of GaAs quantum well lasers with Double Pulse Doped AlGaAs/GaAs/AlGaAs Quantum Well (DPDQW) E/D HEMT electronics on a single substrate in one process run are described. All layers are grown by molecular beam epitaxy. The laser structure, consisting of three 74 Å GaAs quantum wells between two AlGaAs cladding layers, are grown on top of the electronic structure. The laser mesas and contact areas are defined by a combined wet and dry etch process. Apart from the transistor gates which are exposed by electron beam lithography, all lithography steps are performed using contact printing. A two layer metallization is used to interconnect the devices whereby air-bridges are used to connect the laser mesas to the electronics. First results showed laser action of laser diodes of area 3 x 300 μm2 at a threshold current of less than 60 mA, as well as the operation of different electronic devices on wafers which have been processed in this way. These include a laser diode driver, and an optoelectronic receiver with a MSM photo diode, both devices operating at a data rate of 5 Gbit/sec. These results indicate that the process sequence described is suitable for the integration of laser diodes and HEMT electronics.