Comments on "Volume ignition of mixed fuel" by H. Ruhl and G. Korn (Marvel Fusion, Munich)

In the most recent note on Marvel Fusion's concept for a laser driven pB reactor without compression, Ruhl and Korn consider the volumetric energy balance of fusion reactions vs. bremsstrahlung losses in a mixed fuel (DT and pB) environment and claim the satisfaction of this necessary "ideal ignition" condition. Their results are based, however, on improper assumptions about the deposition of fusion energy in the plasma. Correcting for them, we show that the quoted composition of their fuel (a solid boron composite, binding high concentrations of D, T and p) would actually preclude ignition due to the high bremsstrahlung losses associated with the presence of boron. To facilitate ignition, Ruhl and Korn also consider the reduction of the bremsstrahlung losses by confining the radiation in the optically thin fuel region by high Z walls. They suggest to preload this region with radiation so that the radiation temperature equals approximately that of the plasma constituents $T_{r} \approx T_{e} \approx T_{i}$. We show that in this set-up the radiation energy - neglected in these considerations - would, however, vastly exceed the thermal energy of the plasma and actually dominate the ignition energy requirements.Comment: 6 pages, 1 figur

Codier- und Analyse-Schema für physikalische Abbildungen in Schulbüchern

Die Untersuchungen der Qualität von Abbildungen in verschiedenen Schulbüchern, ergaben inte-ressante Ergebnisse bezüglich der verschiedenen Arten von Fehlerkategorien. Es wurde versucht ein Codier- und Analyse-Schema für diese Kategorien von Fehlern in physikalischen Abbildungen zu entwickeln. Berücksichtigt wurden neben den verschiedenen Fehlerklassen (Bildunterschrift, di-daktische Qualität, fachliche Richtigkeit, …) auch die Funktion und Einbettung der Bilder in den Text

Simultaneous Acquisition of EEG and NIRS during Cognitive Tasks for an Open Access Dataset

We provide an open access multimodal brain-imaging dataset of simultaneous electroencephalography (EEG) and near-infrared spectroscopy (NIRS) recordings. Twenty-six healthy participants performed three cognitive tasks: 1) n-back (0-, 2- and 3-back), 2) discrimination/selection response task (DSR) and 3) word generation (WG) tasks. The data provided includes: 1) measured data, 2) demographic data, and 3) basic analysis results. For n-back (dataset A) and DSR tasks (dataset B), event-related potential (ERP) analysis was performed, and spatiotemporal characteristics and classification results for “target” vs. “non-target” (dataset A) and symbol “O” vs. symbol “X” (dataset B) are provided. Time-frequency analysis was performed to show the EEG spectral power to differentiate the task-relevant activations. Spatiotemporal characteristics of hemodynamic responses are also shown. For the WG task (dataset C), the EEG spectral power and spatiotemporal characteristics of hemodynamic responses are analyzed, and the potential merit of hybrid EEG-NIRS BCIs was validated with respect to classification accuracy. We expect that the dataset provided will facilitate performance evaluation and comparison of many neuroimaging analysis techniques

Does simvastatin stimulate bone formation in vivo?

BACKGROUND: Statins, potent compounds that inhibit cholesterol synthesis in the liver have been reported to induce bone formation, both in tissue culture and in rats and mice. To re-examine potential anabolic effects of statins on bone formation, we compared the activity of simvastatin (SVS) to the known anabolic effects of PTH in an established model of ovariectomized (OVX) Swiss-Webster mice. METHODS: Mice were ovariectomized at 12 weeks of age (T0), remained untreated for 5 weeks to allow development of osteopenia (T5), followed by treatment for 8 weeks (T13). Whole, trabecular and cortical femoral bone was analyzed by micro-computed tomography (micro CT). Liquid chromatography/mass spectrometry (LC/MS) was used to detect the presence of SVS and its active metabolite, simvastatin β-hydroxy acid (SVS-OH) in the mouse serum. RESULTS: Trabecular BV/TV at T13 was 4.2 fold higher in animals treated with PTH (80 micro-g/kg/day) compared to the OVX-vehicle treated group (p < 0.001). However, the same comparison for the SVS-treated group (10 mg/kg/day administered by gavage) showed no significant difference (p = NS). LC/MS detected SVS and SVS-OH in mouse serum 20 minutes after gavage of 100 mg SVS. A serum osteocalcin assay (OC) demonstrated that neither bone formation nor osteoblast activity is significantly enhanced by SVS treatment in this in vivo study. CONCLUSIONS: While PTH demonstrated the expected anabolic effect on bone, SVS failed to stimulate bone formation, despite our verification by LC/MS of the active SVS-OH metabolite in mouse serum. While statins have clear effects on bone formation in vitro, the formulation of existing 'liver-targeted' statins requires further refinement for efficacy in vivo

Molecular epidemiology and antimicrobial resistance of Clostridioides difficile detected in chicken, soil and human samples from Zimbabwe

Background: Clostridioides difficile is the major cause of infectious nosocomial diarrhoea in industrialized nations. Data on the occurrence of C. difficile in Africa, ribotype (RT) distribution, antimicrobial susceptibility patterns and potential zoonotic transmission are scarce. Methods: 80 Zimbabwean C. difficile isolates from different sources (chicken [n = 30], soil [n = 21] and humans [n = 29]) were investigated using ribotyping, toxin gene detection, resistance testing, multiple-locus variable-number tandem repeat analysis (MLVA), and whole genome sequencing (WGS). Results: Among chicken isolates, the most common RTs were RT103 (6/30), RT025 (5/30) and RT070 (4/30). Within soil samples, RT025 and RT056 were most common (3/21 each). In contrast, the non-toxigenic RT084 was most frequently found in human isolates (4/29). Toxin genes were detected in only 19/29 human isolates. Susceptibility testing showed no resistance against metronidazole and vancomycin, and resistance against macrolides and rifampicin was scarce (3/80 and 2/80, respectively); however, 26/80 isolates showed moxifloxacin resistance. MLVA and WGS of strains with identical RTs stemming from different sources revealed clustering of RT025 and RT084 isolates from human und non-human samples. Conclusion: No "hypervirulent” strains were found. The detected clusters between human, chicken and soil isolates indicate ongoing transmission between humans and environmental sources and might point towards a zoonotic potential