• Energy Research
• 2021-2025close
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Abstract Hydrogen lines from forming planets are crucial for understanding planet formation. However, the number of planetary hydrogen line detections is still limited. Recent JWST/NIRSpec observations have detected Paschen and Brackett hydrogen lines at TWA 27 B (2M1207b). Although classified as a planetary- mass companison (PMC) rather than a planet due to its large mass ratio to the central star, TWA 27 B’s hydrogen line emissions are expected to be same as the planetary one, given its small mass (≈5M J). We aim to constrain the accretion properties and accretion geometry of TWA 27 B, contributing to our understanding of hydrogen-line emission mechanisms common to both PMCs and planets. We conduct spectral fitting of four bright hydrogen lines (Pa-α, Pa-β, Pa-γ, Pa-δ) with an accretion-shock emission model tailored for forming planets. We estimate the mass accretion rate at M ̇ ≈ 3 × 10 − 9 M J yr − 1 with our fiducial parameters, though this is subject to an uncertainty of up to factor of ten. Our analysis also indicates a dense accretion flow, n ≳ 1013 cm−3 just before the shock, implying a small accretion-shock filling factor f f on the planetary surface (f f ≲ 5 × 10−4). This finding suggests that magnetospheric accretion is occurring at TWA 27 B. Additionally, we carry out a comparative analysis of hydrogen-line emission color to identify the emission mechanism, but the associated uncertainties proved too large for definitive conclusions. This underscores the need for further high-precision observational studies to elucidate these emission mechanisms fully.

The International Atomic Energy Agency (IAEA), jointly with the World Health Organization (WHO), has operated a postal dosimetry audit program for radiotherapy centers worldwide since 1969. In 2017 the IAEA introduced a new methodology based on radiophotoluminescent dosimetry (RPLD) for these audits. The detection system consists of a phosphate glass dosimeter inserted in a plastic capsule that is kept in measuring position with a PMMA holder during irradiation. Correction factors for this holder were obtained using experimental methods. In this work these methods are described and the resulting factors are verified by means of Monte Carlo simulation with the general-purpose code PENELOPE for a range of photon beam qualities relevant in radiotherapy. The study relies on a detailed geometrical representation of the experimental setup. Various photon beams were obtained from faithful modeling of the corresponding linacs. Monte Carlo simulation transport parameters are selected to ensure subpercent accuracy. The simulated correction factors fall in the interval 1.005-1.008 (±0.2%), with deviations with respect to experimental values not larger than 0.2(2)%. This study corroborates the validity of the holder correction factors currently used for the IAEA audits.

A double-null configuration is being considered for the EU-DEMO, due to its potential benefits for power exhaust arising from the use of two active divertors and magnetically disconnected low- and high-field sides. Using systematic parameter scans in fluid simulations, we have investigated the divertor power exhaust in the EU-DEMO in a connected double-null configuration, and compared the edge plasma properties to those obtained in a single-null configuration under detached conditions anticipated for reactor operation. Neglecting drift effects and kinetic behaviour of the neutrals, no clear benefits of the double-null configuration could yet be identified for the radiation pattern and power mitigation on open field lines. Future work should address the aforementioned physics as well as the effect of the additional X-point on core radiation.

AbstractFundamental axes of variation in plant traits result from trade-offs between costs and benefits of resource-use strategies at the leaf scale. However, it is unclear whether similar trade-offs propagate to the ecosystem level. Here, we test whether trait correlation patterns predicted by three well-known leaf- and plant-level coordination theories – the leaf economics spectrum, the global spectrum of plant form and function, and the least-cost hypothesis – are also observed between community mean traits and ecosystem processes. We combined ecosystem functional properties from FLUXNET sites, vegetation properties, and community mean plant traits into three corresponding principal component analyses. We find that the leaf economics spectrum (90 sites), the global spectrum of plant form and function (89 sites), and the least-cost hypothesis (82 sites) all propagate at the ecosystem level. However, we also find evidence of additional scale-emergent properties. Evaluating the coordination of ecosystem functional properties may aid the development of more realistic global dynamic vegetation models with critical empirical data, reducing the uncertainty of climate change projections.

The city’s built environment and functionality play a crucial role in shaping individual mobility patterns, impacting the overall health and quality of life of its population. Understanding these influences is an important research topic, making it a central focus of this paper. This study aims to identify the factors responsible for promoting healthy mobility behavior. To address this comprehensively, a multidisciplinary empirical survey was developed based on the “Triad”—a model consisting of the built environment, mobility(-behavior), and public health. In addition to the evaluation of socio-demographic factors and activity radius mapping, statistical analyses like multiple linear regression were used. These statistical analyses allow the assessment of the impact of various independent variables on the promotion of healthy mobility behavior within urban settings. The multiple regression shows that the satisfaction with the accessibility of public transport and the sense of safety as a cyclist contribute to explaining the variation of healthy mobility. Furthermore, the satisfaction with walking in the neighborhood and the inhalation of exhaust fumes while walking also seem to have an impact. The results show the link between the Triad and make it clear that mobility planning and urban planning must take a more integrated approach to promote health and simultaneously protect the climate.