Domain and Geometry Agnostic CNNs for Left Atrium Segmentation in 3D Ultrasound

Segmentation of the left atrium and deriving its size can help to predict and detect various cardiovascular conditions. Automation of this process in 3D Ultrasound image data is desirable, since manual delineations are time-consuming, challenging and observer-dependent. Convolutional neural networks have made improvements in computer vision and in medical image analysis. They have successfully been applied to segmentation tasks and were extended to work on volumetric data. In this paper we introduce a combined deep-learning based approach on volumetric segmentation in Ultrasound acquisitions with incorporation of prior knowledge about left atrial shape and imaging device. The results show, that including a shape prior helps the domain adaptation and the accuracy of segmentation is further increased with adversarial learning

Fluid substitution in porous rocks with aligned cracks: Theory versus numerical modeling

The effect of penny-shaped cracks on the elastic properties of porous media is modeled using static finite element modeling (FEM) code. Anisotropic Gassmann theory is used to predict the effective properties of the saturated cracked media from their dry properties. There is an excellent agreement between numerical results and theory, with a small error associated with partially inequilibrated patches of fluid in the FEM. These patches of fluid result in a residual stiffness which can be subtracted from the FEM results to further improve agreement with Gassmann theory

Finite element modelling of the effective elastic properties of partially saturated rocks

Simulation of effective physical properties from microtomographic 3D images of porous structures allows one to relate properties of rocks directly to their microstructure. A static FEM code has been previously used to estimate effective elastic properties of fully saturated monomineralic (quartz) rock under wet and dry conditions. We use the code to calculate elastic properties under partially saturated conditions. The numerical predictions are compared to the Gassmann theory combined with Wood's formula (GW) for a mixture of pore fluids, which is exact for a monomineralic macroscopically homogeneous porous medium. Results of the numerical simulations performed for two Boolean sphere pack distributions show significant deviation from the GW limit and depend on the spatial distribution of fluids. This is shown to be a numerical artefact caused by incomplete equilibration of fluid pressure, which is primarily due to insufficient spatial resolution. To investigate the effect of pore-size and pore geometry, we perform FEM simulations for a model with regular pore geometry, where all pore channels have the same size and shape. Accuracy of these simulations increases with the total cross-section area of the channels and the size of individual channels. For the case where the total cross-section of the channels is large enough (on the same order as total porosity), there is a minimum of 4 voxels per channel diameter required for adequate fluid pressure equilibration throughout the pore space. Increasing the spatial resolution of the digital models reduces the discrepancy between the simulations and theory, but unfortunately increases the memory and CPU requirements of the simulations

Ada and Knowledge-Based Systems: A Prototype Combining the Best of Both Worlds

We describe a software architecture based on Ada tasking and packaging which facilitates the construction of distributed knowledge-based systems. We used this architecture to build the Knowledge-Based Maintenance Expert System (KNOMES) prototype for the Remote Manipulator System (RMS) of the NASA Space Station Mobile Service Center. Each module of the system contains Ada packages of standard systems services, which interface with an artificial intelligence/ knowledge-based system (AI/KBS) language component that performs knowledge-based reasoning. By using Ada as the fundamental structure, we achieved a well-structured, maintainable program; by retaining the AI/KBS language component, we were able to capture the knowledge needed to solve illstructured, dynamic, and/or nonalgorithmic problems

Stressed backbone and elasticity of random central-force systems

We use a new algorithm to find the stress-carrying backbone of ``generic'' site-diluted triangular lattices of up to 10^6 sites. Generic lattices can be made by randomly displacing the sites of a regular lattice. The percolation threshold is Pc=0.6975 +/- 0.0003, the correlation length exponent \nu =1.16 +/- 0.03 and the fractal dimension of the backbone Db=1.78 +/- 0.02. The number of ``critical bonds'' (if you remove them rigidity is lost) on the backbone scales as L^{x}, with x=0.85 +/- 0.05. The Young's modulus is also calculated.Comment: 5 pages, 5 figures, uses epsfi

Создание опытного образца геохода. Временной фактор изготовления компонентов и их сборки в конечное изделие

Изложен опыт реализации проекта №02.G25.31.0076 в рамках открытого конкурса Министерства образования и науки РФ и Постановления Правительства РФ №218 от 09.04.2010 г. Дано описание временных рамок реализации проекта, в частности, работы над созданием опытного образца щитового проходческого агрегата - геохода, диаметром 3,2 м. В настоящее время проект находится в стадии завершения. Главная идея статьи - поделиться опытом создания новой техники и показать, сколько времени затрачивается на решение тех или иных производственных процессов по созданию опытных образцов горных машин на примере геохода. Данная статья будет полезна организациям, планирующим участие в реализации проектов по созданию высокотехнологичного производства, и может являться ориентиром для составления Плана-графика реализации подобных проектов. Автор статьи лично принимал участие в реализации данного проекта и принимал решения по планированию и организации работ.The experience of the project №02.G25.31.0076 is presented. The project was operated in the framework of the open competition of the Ministry of education and science of the Russian Federation and the RF Government Decree №218 from 09.04.2010. Description of the time frame of the project implementation, particularly the activities of the TBM prototype creation - geokhod, with a diameter of 3.2 m. is presented. Currently, the project is closer to complete. The main idea of the article is to share the experience of creating new technology and show how much time is spent on the decision of production processes to create prototypes of mining machines on the example of a geokhod. This article will be useful for organizations planning to participate in the implementation of projects to create high-tech production, and can be a guide for drawing up a Plan-schedule of such projects. The author of this article personally participated in the implementation of this project and made decisions on planning and organization of activities

Dynamics of Wetting Fronts in Porous Media

We propose a new phenomenological approach for describing the dynamics of wetting front propagation in porous media. Unlike traditional models, the proposed approach is based on dynamic nature of the relation between capillary pressure and medium saturation. We choose a modified phase-field model of solidification as a particular case of such dynamic relation. We show that in the traveling wave regime the results obtained from our approach reproduce those derived from the standard model of flow in porous media. In more general case, the proposed approach reveals the dependence of front dynamics upon the flow regime.Comment: 4 pages, 2 figures, revte

Deletion of the GABAA α2-subunit does not alter self dministration of cocaine or reinstatement of cocaine seeking

Rationale GABAA receptors containing α2-subunits are highly represented in brain areas that are involved in motivation and reward, and have been associated with addiction to several drugs, including cocaine. We have shown previously that a deletion of the α2-subunit results in an absence of sensitisation to cocaine. Objective We investigated the reinforcing properties of cocaine in GABAA α2-subunit knockout (KO) mice using an intravenous self-administration procedure. Methods α2-subunit wildtype (WT), heterozygous (HT) and KO mice were trained to lever press for a 30 % condensed milk solution. After implantation with a jugular catheter, mice were trained to lever press for cocaine (0.5 mg/kg/infusion) during ten daily sessions. Responding was extinguished and the mice tested for cue- and cocaine-primed reinstatement. Separate groups of mice were trained to respond for decreasing doses of cocaine (0.25, 0.125, 0.06 and 0.03 mg/kg). Results No differences were found in acquisition of lever pressing for milk. All genotypes acquired self-administration of cocaine and did not differ in rates of self-administration, dose dependency or reinstatement. However, whilst WT and HT mice showed a dose-dependent increase in lever pressing during the cue presentation, KO mice did not. Conclusions Despite a reported absence of sensitisation, motivation to obtain cocaine remains unchanged in KO and HT mice. Reinstatement of cocaine seeking by cocaine and cocaine-paired cues is also unaffected. We postulate that whilst not directly involved in reward perception, the α2-subunit may be involved in modulating the “energising” aspect of cocaine’s effects on reward-seeking