[en] A preliminary investigation into the efficacy of a new 3D dosimetry material, RadGel^TM, for verification of radiation therapy dose distributions is presented. Small volumes of RadGel^TM were found to exhibit a linear, reproducible response to dose. A gradual increase in optical-density (OD) with time was observed, suggesting scanning should be completed within 18 hours to keep a linear correlation of R² > 0.99. A larger 10 cm diameter volume of RadGel^TM was irradiated with a rotationally symmetric 'spoke' plan designed to rigorously evaluate scanner/dosimeter combined performance. The dosimeter was imaged with the Duke Mid-sized Optical-CT Scanner (DMOS). Promising OD and corresponding dose maps were obtained. Edge artefacts were observed and are suspected to be exacerbated by the particular container used in this early study. Further studies will evaluate new containers and methods for refractive matching at the gel-container-fluid interface.

[en] Complete text of publication follows: We wish to develop a rigorous theoretical treatment that can be used to model the behaviour of systems that contain actinides, such as the uranyl ion, in aqueous solution. These solutions will contain coordinating anions such as sulphate, carbonate, or halides. For reasons of computational efficiency, DFT methods seem to be essential, as does the use of an ECP. But which version of DFT is the most suitable? How many electrons need to be treated explicitly on the actinide? To answer these questions, we have examined the performance of many different functionals and two different ECP. The experimental test data include geometries, vibrational frequencies, reaction enthalpies and NMR chemical shifts. We present below two representations of the uranyl ion in aqueous solution: 17 or 26 water molecules have been included in an ONIOM-type treatment. It is clear that 26 molecules are not sufficient for a balanced description of the aqueous solution

[en] The statistical distributions of active galactic nuclei (AGNs), i.e., accreting supermassive black holes (BHs), in mass, space, and time are controlled by a series of key properties, namely, the BH–galaxy scaling relations, Eddington ratio distributions, and fraction of active BH (duty cycle). Shedding light on these properties yields strong constraints on the AGN triggering mechanisms while providing a clear baseline to create useful mock catalogs for the planning of large galaxy surveys. Here we delineate a robust methodology to create mock AGN catalogs built on top of large N-body dark matter simulations via state-of-the-art semiempirical models. We show that by using as independent tests the AGN clustering at fixed X-ray luminosity, galaxy stellar mass, and BH mass, along with the fraction of AGNs in groups and clusters, it is possible to significantly narrow down the choice in the relation between BH mass and host galaxy stellar mass, the duty cycle, and the average Eddington ratio distribution, delivering well-suited constraints to guide cosmological models for the coevolution of BHs and galaxies. Avoiding such a step-by-step methodology inevitably leads to strong degeneracies in the final mock catalogs, severely limiting their usefulness in understanding AGN evolution and in survey planning and testing.