Search

Objective: Risk stratification based on standardized quality measures has become crucial in neurosurgery. Contemporary quality indicators have often been collectively developed for a wide range of neurosurgical procedures. While these indicators are easy to register, their accuracy for tumor inherent [for full text, please go to the a.m. URL]

The potential of time-of-flight recoil detection in transmission geometry using pulsed keV ion beams for sensitive multi-element profiling of thin membranes and quasi-2D systems is assessed. While the time-of-flight approach allows for simultaneous detection of multiple elements, to the largest extent irrespective of recoil charge states, the keV projectile energies guarantee high recoil-cross sections yielding high sensitivity at low dose. We demonstrate the capabilities of the approach using 22Ne and 40Ar as projectiles transmitted through thin carbon foil featuring optional LiF-coatings and single crystalline silicon membranes for different sample preparation routines and crystal orientations. For a large position sensitive detector (0.13 sr), a high-depth resolution below 6 nm and sensitivity below 1014 atoms/cm2 was achieved. For crystalline targets, we show how the probability of creation and detection of recoils and their observed angular distribution depend on sample orientation.

High-entropy alloys (HEAs) are a relatively new class of metal alloys composed of several principal elements, usually at (near) equiatomic ratios. It has previously been reported that some HEAs display superior radiation damage resistance, with composition and microstructure being cited as contributing factors, though the precise mechanism is still unknown. To study the influence of the crystal structure on the response to radiation, we have chosen FeCoCrNiV as a model system. While FeCoCrNi has a face-centred cubic (fcc) structure, adding V leads to a structural transformation towards a body-centred tetragonal (bct) structure with both phases present at near-stochiometric composition. The as-cast sample was characterised by energy-dispersive X-ray spectroscopy (EDXS) and electron backscatter diffraction in a scanning electron microscope confirming the presence of both phases. Irradiations were performed with a focussed He beam provided by a helium ion microscope (HIM) at temperatures between 20°C and 500°C. The fluence was varied between 6×10^17 ions/cm² and 1×10^20 ions/cm². High-resolution images of the irradiated areas were taken with the same HIM as shown in Fig. 1a. Selected irradiated areas were additionally studied by transmission electron microscopy (TEM) in combination with EDXS. Under irradiation, pores start to be generated in the material with pore sizes differing significantly between the two phases. At higher fluences and above a critical temperature, a tendril structure as exemplary shown for the bct phase in Fig. 1a forms in both phases. TEM images reveal that these tendrils span the whole depth of the irradiated area (Fig. 1b) and are accompanied by bubbles of various sizes. Scanning TEM-based EDXS of these structures indicates a He-induced change in composition.

High-entropy alloys (HEAs) are a relatively new class of metal alloys composed of several principal elements, usually at (near) equiatomic ratios. It has previously been reported that some HEAs display superior radiation damage resistance, with composition and microstructure being cited as contributing factors, though the precise mechanism is still unknown. To study the influence of the crystal structure on the response to radiation, we have chosen FeCoCrNiV as a model system. While FeCoCrNi has a face-centred cubic (fcc) structure, adding V leads to a structural transformation towards a body-centred tetragonal (bct) structure with both phases present at near-stochiometric composition [1]. The as-cast sample was characterised by energy-dispersive X-ray spectroscopy (EDXS) and electron backscatter diffraction (EBSD) in a scanning electron microscope (SEM) confirming the presence of both phases. Irradiations were performed with a focussed He beam provided by a helium ion microscope (HIM) at temperatures between room temperature and 500°C. The irradiation fluence was varied between 6x1017 ions/cm2 and 1x1020 ions/cm2. High-resolution images of the irradiated areas were taken with the same HIM, and an example is shown in Fig. 1a. Selected irradiated areas were additionally studied by transmission electron microscopy (TEM) in combination with EDXS. Under irradiation, pores start to be generated in the material with pore sizes differing significantly between the two phases. At higher fluences and above a critical temperature, a tendril structure as exemplary shown for the bct phase in Fig. 1a forms in both phases. We have found that the critical temperature depends on the phase and is lower for fcc. TEM images reveal that the tendrils span the whole depth of the irradiated area and are accompanied by bubbles of various sizes as shown in Fig. 1b for the bct phase. Scanning TEM-based EDXS of these structures indicates a He-induced change in composition. A.G. acknowledges support by the Royal Academy of Engineering and the Leverhulme Trust.

The helium ion microscope (HIM) is an instrument for high-resolution imaging, composition analysis, and materials modification at the nanoscale. Ion transmission experiments could further improve the analytical capabilities of this technique, and multiple contrast modes are possible. We explore the latter at keV ion energies using a HIM in a scanning transmission approach as well as a broad beam in combination with a time-of-flight (ToF) set-up. Both systems employ positionsensitive detectors allowing for analysis of angular distributions. In the ToF-system, we find a strong trajectory-dependence of the measured specific energy loss attributed to charge-exchange events in close collisions. Channelling and blocking of transmitted ions allows for mapping of intensity as well as different energy loss moments. In the HIM we demonstrate different contrasts, e.g., due to orientation of nanocrystals, channelling in single-crystalline membranes and material contrast for layered films.

Collective cellular behavior in confluent monolayers supports physiological and pathological processes of epithelial development, regeneration, and carcinogenesis. Here, the attainment of a mature and static tissue configuration or the local reactivation of cell motility involve a dynamic regulation of the junctions established between neighboring cells. Tricellular junctions (tTJs), established at vertexes where three cells meet, are ideally located to control cellular shape and coordinate multicellular movements. However, their function in epithelial tissue dynamic remains poorly defined. To investigate the role of tTJs establishment and maturation in the jamming and unjamming transitions of epithelial monolayers, a semi-automatic image-processing pipeline is developed and validated enabling the unbiased and spatially resolved determination of the tTJ maturity state based on the localization of fluorescent reporters. The software resolves the variation of tTJ maturity accompanying collective transitions during tissue maturation, wound healing, and upon the adaptation to osmolarity changes. Altogether, this work establishes junctional maturity at tricellular contacts as a novel biological descriptor of collective responses in epithelial monolayers.

As climate change continues to be politically divisive, developing communications that align with right-leaning beliefs may increase bipartisan support for climate policy. In two experimental studies (Study 1, Australia, N = 558; Study 2, United States, N = 859), we tested whether an economic loss or national identity loss message would elicit greater support for mitigation and adaptation policies when compared to one another and to a control message. We also tested whether the direct effects of these message types were conditional on political orientation (specifically, identifying as politically right-leaning). In both studies, preliminary analyses indicated that the message manipulations were effective and that there was a high level of support for both types of climate policy. When compared to left-wing adherents, those who were politically right-leaning were less likely to support mitigation and adaptation policies in either sample. Australian (Study 1) identification – although not American identity (Study 2) – also uniquely predicted adaptation support (but not mitigation support). Yet, there were no significant message frame or interaction effects in the Australian (Study 1) or U.S. sample (Study 2). This suggests that neither an economic loss nor national identity loss message frame may be effective in overcoming the political polarization of climate change in Australia or the United States. Nevertheless, national identity could still play a useful role in Australian climate communications given its positive relationship to adaptation policy support, and therefore warrants further investigation.

We present experiments directly demonstrating the significance of charge-exchange events for the energy deposition of ions with velocities below the Bohr velocity. The observed effects lead to a drastic trajectory-dependence of the specific energy loss. Experiments were performed with the time-of-flight medium energy ion scattering set-up at Uppsala University [1]. We employed pulsed beams of singly charged ions with masses ranging from 1 (H+) to 40 u (Ar+) and energies between 20 and 350 keV. Ions were transmitted through self-supporting Si(100) nanomembranes and detected behind the sample. We assessed the energy and angular distributions of deflected particles for different alignments of the initial beam direction with the crystal axes and planes. A set-up for measuring the exit charge state was constructed to support the analysis [2]. For all ions we observe lower electronic stopping for channelled trajectories as compared to random ones as shown in Fig. 1 [3]. For protons, this difference is explained by increasing contributions of core-electron excitations more likely to happen at small impact parameters accessible only in random geometry. For heavier ions, core-electron excitations at employed ion velocities are inefficient and we, therefore, explain these results by reionisation events occurring in close collisions of ions with target atoms [4]. These events in turn result in trajectory-dependent mean charge states, which heavily affects the energy loss, and could be confirmed by first qualitative measurements of the trajectory dependence of exit charge states. The simplicity of our experimental geometry leads to results that can serve as excellent benchmark systems for calculations using time-dependent density functional theory. References [1] M. A. Sortica et al., Nucl. Instrum. Methods Phys. Res. B, 463 (2020) 16-20. [2] R. Holeňák et al., Vacuum, 185 (2021) 109988. [3] S. Lohmann et al., Phys. Rev. A, 102 (2020) 062803. [4] S. Lohmann and D. Primetzhofer, Phys. Rev. Lett., 124 (2020) 096601.

Hintergrund: Ischämische Prozesse spielen eine wichtige Rolle in der Pathophysiologie verschiedener Augenerkrankungen, wie Glaukom, okuläre Gefäßverschlüsse oder diabetische Retinopathie. Ischämie-Reperfusion (I/R) führt zu funktionellen und morphologischen Schädigungen[zum vollständigen Text gelangen Sie über die oben angegebene URL], 31. Kongress der Deutschsprachigen Gesellschaft für Intraokularlinsen-Implantation, Interventionelle und Refraktive Chirurgie (DGII)

INTRODUCTION / BACKGROUND: Biobanks and their operators are gaining popularity. However, they face a range of growing challenges. Many of these biobanks used to be smaller and midsized collections of data and samples, but are now being developed into centralized networks within clinics and consortia. These large biobanks require the integration of as many sources of information as possible, including imaging data in addition to any relevant structured data. This is especially the case in the field of virtual microscopy. Data collection is increasingly being orchestrated by workflow based systems and must eventually be incorporated entirely into rule based IT-processes. AIMS: In order to achieve this goal, the Charité University Medicine Berlin, VMscope GmbH, and Kairos GmbH formed a consortium in the framework of the joint project, “Biobanking 3.0”, which is funded by the German Federal Ministry for Education and Research (BMBF). Furthermore, after this successful project, a second KMU funded project called POST (Patient-centric Open Multi Center Study Tool) will begin in the autumn of 2015 to expand the data integration to pathology information systems in a standardized manner. METHODS: One of the project goals is to use an IT-platform with an integrated workflow-engine to orchestrate all necessary processes and document all findings. Defined SOPs during sample extraction and information acquisition can be executed, and all result data can be made available to local research groups as well as project partners. RESULTS: Thus, the platform pursues the research approach of personalized medicine, which requires exact controlling of therapy cycles in a logical and chronological order.

The CSR electron cooler will be employed both for phase space cooling and as a target for electron-ion collision experiments. Aligning the beams is essential for both applications and, therefore, the cooler features two rotating wire scanners for beam position determination. In the course of this work their design has been finalised. A scheme has been developed to calculate the transverse beam location from two measured rotation angles. This can be utilised to determine the centres of the electron and ion beams. While in the former case a signal is directly induced at the wires, identification of the latter depends on an increasing restriction of phase space with advancing rotation. A procedure is proposed to detect the decline in ion intensity with the CSR’s current pick-up. Furthermore, the electron collector of the cooler has been designed and assembled. A Wien filter is included to minimise backstreaming of secondary electrons, which will prolong the lifetime of the GaAs photocathode. Calculations and a simulation were conducted to optimise its design. Additionally, an analyser cup allows for beam profile and energy distribution measurements. From this, among others, the electron density can be computed, which is necessary for rate coefficient calculations.