Ice Formation in Model Biological Membranes in the Presence of Cryoprotectors

Ice formation in model biological membranes is studied by SAXS and WAXS in the presence of cryoprotectors: dimethyl sulfoxide and glycerol. Three types of phospholipid membranes: DPPC, DMPC, DSPC are chosen for the investigation as well-studied model biological membranes. A special cryostat is used for sample cooling from 14.1C to -55.4C. The ice formation is only detected by WAXS in binary phospholipid/water and ternary phospholipid/cryoprotector/water systems in the condition of excess solvent. Ice formation in a binary phospholipid/water system creates an abrupt decrease of the membrane repeat distance by delta-d, so-called ice-induced dehydration of intermembrane space. The value of delta-d decreases as the cryoprotector concentration increases. The formation of ice does not influence the membrane structure (delta-d = 0) for cryoprotector mole fractions higher than 0.05.Comment: PDF: 9 pages, 3 figures; sourse in MS Wor

Edge- and detail-preserving sparse image representations for deformable registration of chest MRI and CT volumes

Deformable medical image registration requires the optimisation of a function with a large number of degrees of freedom. Commonly-used approaches to reduce the computational complexity, such as uniform B-splines and Gaussian image pyramids, introduce translation-invariant homogeneous smoothing, and may lead to less accurate registration in particular for motion fields with discontinuities. This paper introduces the concept of sparse image representation based on supervoxels, which are edge-preserving and therefore enable accurate modelling of sliding organ motions frequently seen in respiratory and cardiac scans. Previous shortcomings of using supervoxels in motion estimation, in particular inconsistent clustering in ambiguous regions, are overcome by employing multiple layers of supervoxels. Furthermore, we propose a new similarity criterion based on a binary shape representation of supervoxels, which improves the accuracy of single-modal registration and enables multi-modal registration. We validate our findings based on the registration of two challenging clinical applications of volumetric deformable registration: motion estimation between inhale and exhale phase of CT scans for radiotherapy planning, and deformable multi-modal registration of diagnostic MRI and CT chest scans. The experiments demonstrate state-of-the-art registration accuracy, and require no additional anatomical knowledge with greatly reduced computational complexity. © 2013 Springer-Verlag

Use of ultrasound scanning to estimate teat wall thickness in Murciano-Granadina goats

[EN] To evaluate the ultrasound technique as a method for estimating the effect of mechanical milking on teat thickness in Murciano-Granadina goats, the following work was carried out with a twofold objective: (1) to study the most suitable ultrasound exploration frequency for this breed and the effect of the operator in applying the technique and (2) to validate the approach, comparing it with measurements taken by another estimation method (cutimeter) and performing ultrasound examinations in cows using the same methodology. To this end, three studies were designed. In the first study, 2 experiments were carried out: (a) the first (El) tested the frequencies 5, 7.5 and 10 MHz; (b) the second (E2) tested the frequencies 3.5 and 5 MHz. In the second study, 2 different independent operators (OP) performed sonography on the same animals (B), chose the best image of ultrasound examinations recorded as a video sequence (E4) and carried out measurements on ultrasound images (E5). In the third study, the technique tested in goats was applied in 10 Holstein cows (E6) and, finally, ultrasound scans were performed at 5 MHz frequency and cutimeter measurements taken in 63 goats (E7). The following variables were measured in the ultrasound scans: teat wall thickness (TWT), teat wall area (TWA) and teat end area (TEWA). The cutimeter was also used to measure teat wall thickness (TT). From the results obtained, we observed that frequencies of 5 and 7.5 MHz were the most suitable to estimate the teat wall changes brought about by mechanical milking. Moreover, applying the same methodology and frequencies in Holstein cows, the results achieved were similar to those published in the bibliography and the variables measured (TWT, TWA and TEWA) presented a high and significant correlation (R=0.62) with the variable (IT) measured by cutimeter. OP experience had an effect on TEWA before milking in all three experiments (E3-E5) and in TWT, TWA and TEWA after milking in E4 and E5. Despite the effects observed for some variables before and after milking, a significant effect was only found for the difference (after-before milking) in TEWA in E3 and TWT in E4. The ultrasound technique used can serve as a useful tool to evaluate teat wall thickness changes caused by mechanical milking in goats. Nevertheless, it would be appropriate to carry out another study to develop IT tools to minimise the operator effect in the measurement of ultrasound variables. (C) 2013 Elsevier B.V. All rights reserved.The study was supported by Project AGL2006-06909 (Ministerio de Educacion y Ciencia and FEDER).Díaz, J.; Alejandro, M.; Peris Ribera, CJ.; Fernández Martínez, N. (2013). Use of ultrasound scanning to estimate teat wall thickness in Murciano-Granadina goats. Livestock Science. 155(1):114-122. https://doi.org/10.1016/j.livsci.2013.04.007S114122155