Automatic segmentation of intracochlear anatomy in conventional CT

Cochlear implant surgery is a procedure performed to treat profound hearing loss. Clinical results suggest that implanting the electrode in the scala tympani, one of the two principal cavities inside the cochlea, may result in better hearing restoration. Segmentation of intracochlear cavities could thus aid the surgeon to choose the point of entry and angle of approach that maximize the likelihood of successful implant insertion, which may lead to more substantial hearing restoration. However, because the membrane that separates the intracochlear cavities is too thin to be seen in conventional in vivo imaging, traditional segmentation techniques are inadequate. In this paper, we circumvent this problem by creating an active shape model with micro CT (μCT) scans of the cochlea acquired ex vivo. We then use this model to segment conventional CT scans. The model is fitted to the partial information available in the conventional scans and used to estimate the position of structures not visible in these images. Quantitative evaluation of our method, made possible by the set of μCTs, results in Dice similarity coefficients averaging 0.75. Mean and maximum surface errors average 0.21 and 0.80 mm.     

Towards treatment planning for the embolization of arteriovenous malformations of the brain: intranidal hemodynamics modeling

This paper presents a patient-derived model for the simulation of the hemodynamics of arteriovenous malformations of the brain (BAVM). This new approach is a step toward the simulation of the outcome of the embolization of the BAVM during treatment planning. More specifically, two aspects of the planning are pursued: simulation of the change of blood flow in the brain vasculature after the blocking of the malformation and simulation of the transport of the embolic liquid. The method we propose is tested on 3 BAVM cases of varying complexity. Twenty two out of 24 main BAVM flow paths have been identified well by simulation.     

Manipulation of the fatty acid composition of pig meat lipids by dietary means

Pigmeat products have been associated with an unhealthy image due to the relative proportions of polyunsaturated and saturated fatty acids. The aim of this experiment was to improve the fatty acid profile of the carcass fat by feeding various dietary sources of fat. Groups of 10 female Large While × Landrace pigs were fed one of four experimental diets. Five in each group were slaughtered at 70 kg live weight and the remaining five at 100 kg live weight. The diets were offered ad libitum and daily intake was recorded. The diets were based on barley, soya bean meal and fishmeal. Diet 1 contained 50 g tallow kg^?1, a relatively saturated fat, and diets 2, 3 and 4 contained 50 g soya oil kg^?1, an unsaturated fat. Diet 3 also contained 7.5 g GLA oil kg^?1, which is rich in gamma linolenic acid, with the aim of increasing the production of arachidonic acid in the body fat. Diet 4 was supplemented with 9.5 g EPAnoil kg^?1, which is rich in eicosapentaenoic acid and docosahexaenoic acid. There were no significant differences between dietary treatments in performance (daily liveweight gain or the efficiency of food conversion to liveweight gain) of the pigs slaughtered at 70 kg live weight, but small differences were observed at 100 kg live weight, where pigs on treatments 2, 3 and 4 performed slightly better than those on treatment 1. At both slaughter weights the lipid content of the m semitendinosus was higher than that of the m longissimus dorsi (approximately 24 and 13 g kg^?1, respectively). The pattern of fatty acids in the dietary fat was reflected to varying degrees in the carcass fat. Diet 1 resulted in the highest levels of palmitic, palmitoleic, stearic and oleic acids whereas diets 2, 3 and 4 gave high levels of linoleic and linolenic acids. The extra gamma linolenic acid in diet 3 did not result in a consistently significant increase in the production of arachidonic acid. The supplement of EPAnoil gave significant increases in the levels of eicosapentaenoic and docosahexaenoic acids in the body lipids. The polyunsaturated to saturated fatty acid ratio of the body lipid was increased with diets 2, 3 and 4 to about 1.0. In spite of high levels of linoleic acid, there were no adverse effects during the processing of the carcasses and the taste panel evaluation did not reveal any treatment differences.     

Measurements and analysis of turbulent consumption speeds of H2/CO mixtures

This paper describes measurements of global turbulent consumption speeds, S_T,GC, of hydrogen/carbon monoxide (H₂/CO) mixtures. The turbulent flame properties of such mixtures are of fundamental interest because of their strong stretch sensitivity, and of practical interest since they are the primary constituents of syngas fuels. Data are reported at mean flow velocities and turbulence intensities of 4 < U₀ < 50 m/s and , respectively, for H₂/CO blends ranging from 30% to 90% H₂ by volume. Two sets of experiments are reported. In the first, fuel blends ranging from 30% to 90% H₂ and mixture equivalence ratio, ?, were adjusted at each fuel composition to have nominally the same un-stretched laminar flame speed, S_L,0. In the second set, equivalence ratios were varied at constant H₂ levels. The data clearly corroborate results from other studies that show significant sensitivity of S_T,GC to fuel composition. In particular, at a fixed and S_L,0, values of S_T,GC increase by a factor of almost 2 when H₂ levels are increased from 30% (at ? = 0.61) to 90% (at ? = 0.48). Moreover, S_T,GC in the 90% H₂ case is three times larger than the ? = 0.9 CH₄/air mixture with the same S_L,0 value. An important conclusion from this work is these fuel effects are not simply a low turbulence intensity phenomenon – they clearly persist over the entire range of turbulence intensities used in the measurements. We also describe physics-based correlations of these data, using leading points concepts and detailed kinetic calculations of the stretch sensitivity of these mixtures. These results are used to develop an inequality for negative Markstein length flames that bounds the turbulent flame speed data and show that the data can be collapsed using the maximum stretched laminar flame speed, S_L,max, rather than S_L,0.