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- Dobsicek Trefna, Hana, 1979, et al.
(författare)
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Antenna Applicator for Microwave Hyperthermia Treatment of Pediatric Brain Cancer
- 2014
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Ingår i: 8th European Conference on Antennas and Propagation, EuCAP 2014, The Hague, The Netherlands 6-11 April 2014. - 9788890701849
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A novel antenna applicator for microwave hyperthermia allowing treatment of deep brain tumors is proposed. The applicator consists of up to 16 antennas placed around the head in a helmet-like set-up and operates at a frequency range of 430-1000~MHz. The self-grounded bow-tie antennas are housed in a molded plastic enclosure with the shape of a truncated cone. The inner space of the enclosure is filled with distilled water. The antennas are attached to a perimetric water bolus with a thickness of 2 cm and aligned with the head shape. The focusing ability of the applicator was investigated on a homogeneous SAM model and on a model of a 13-year old patient containing a spherical tumor of 2 cm radius. Two different tumor positions were investigated: the right frontal lobe and the central brain. The obtained SAR distributions are favorable, although a relatively high level of energy is also absorbed on the surface of the body. This heating is however not expected to cause problems as it can be cooled by blood perfusion and water bolus. Our results show that focused microwave heating in the brain is feasible and warrants further verification on phantoms.
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| 2. |
- Vessman, Björn, 1988, et al.
(författare)
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Estimating the probability of coexistence in cross-feeding communities
- 2016
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Ingår i: Journal of Theoretical Biology. - : Elsevier BV. - 0022-5193 .- 1095-8541. ; 408:7, s. 13-21
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Tidskriftsartikel (refereegranskat)abstract
- The dynamics of many microbial ecosystems are driven by cross-feeding interactions, in which metabolites excreted by some species are metabolised further by others. The population dynamics of such ecosystems are governed by frequency-dependent selection, which allows for stable coexistence of two or more species. We have analysed a model of cross-feeding based on the replicator equation, with the aim of establishing criteria for coexistence in ecosystems containing three species, given the information of the three species’ ability to coexist in their three separate pairs, i.e. the long term dynamics in the three two-species component systems. The triple-system is studied statistically and the probability of coexistence in the species triplet is computed for two models of species interactions. The interaction parameters are modelled either as stochastically independent or organised in a hierarchy where any derived metabolite carries less energy than previous nutrients in the metabolic chain. We differentiate between different modes of coexistence with respect to the pair-wise dynamics of the species, and find that the probability of coexistence is close to 1/2 for triplet systems with three pair-wise coexistent pairs and for the so-called intransitive systems. Systems with two and one pair-wise coexistent pairs are more likely to exist for random interaction parameters, but are on the other hand much less likely to exhibit triplet coexistence. Hence we conclude that certain species triplets are, from a statistical point of view, rare, but if allowed to interact are likely to coexist. This knowledge might be helpful when constructing synthetic microbial communities for industrial purposes.
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