Ceramics based on titanium nitride and silicon nitride sintered by SPS-method

The dependences of the microstructure and physical and mechanical properties of ceramic mixtures Si[3]N[4]/TiN in the full range of mass ratios of the components. Was also investigated directly, and the process of sintering occurring during a physical or chemical processes, in particular, has been obtained and the hardness of the material density on the ratio of the conductive titanium nitride phase and a silicon nitride insulating phase with values above and below the percolation threshold. Also obtained was pure ceramics based on titanium nitride with high physical-mechanical characteristics (H=21.5 GPa)

The State of Hip Arthroscopy in Russia: Assessment Based on a Sociological Survey of Doctors

Background. Hip arthroscopy is a minimally invasive surgical technique most commonly performed to correct femoroacetabular impingement (FAI). Currently, it is widely used by worldwide; in addition, there are a significant number of english-language publications on this topic. The number of hip arthroscopy performed in Russia is unknown. Information about this surgical technique is also very limited in our country. The aim of the study was to assess the level of hip arthroscopy in Russia. Methods. A total sociological survey of orthopaedic surgeon with experience in performing hip arthroscopy was conducted. The questionnaire was posted on the Google Forms platform and consisted of 13 questions of closed, semi-closed and open types. The survey included 54 surgeons from Russian clinics, 45 people filled out the questionnaire. Results. Among the respondents, doctors with experience in performing arthroscopic operations on the knee and shoulder joints predominated (100.000.00% and 93.300.03%, respectively). The majority of specialists (73.300.06%) were trained in hip arthroscopy during the primary course in one of the clinics in Russia. More than half of the respondents (68.800.06%) are currently engaged in this surgical area, however, in 45.160.07% of them, the number of operations does not exceed 5 per year. For surgeons who have completed two or more training courses, the volume of operations performed is higher (p0.05); 51.110.07% of doctors perform arthroscopy using an alternative technique. There are 2.5 time more specialists doing just bone resection, than surgeons who apply any kind of reconstruction technique while treating FAI (p0.05). Fifteen respondents (48.390.08%) perform debridement as an attempt to delay arthroplasty. The most common difficulties faced by surgeon are problems with the diagnosis of FAI (no patients) (40.000.02%), lack of the necessary tools (40.000.02%) and sufficient time to master the technique (33.300.07%). Only three (6.600.07%) respondents believe that they manage to achieve the planned results of the operation, 93.300.03% of surgeons said that it is not always possible to achieve the desired outcomes. Conclusion. Hip arthroscopy in Russia is not very common, the volume of such interventions is insignificant. Doctors with minimal skills in arthroscopic hip surgery predominate. Factors that impede the development of this area in our country are related to teaching methods, problems with FAI diagnostics, the lack of necessary instruments for performing operations, and the lack of time for specialists to master surgical techniques

Emotional social robot "Emotico"

This work presents high level design and preliminary results of the implementation of an psycho-emotional system based on DA and 5-HT subsystems implementing 4 basic emotions

Chern-Simons Theory in the Temporal Gauge and Knot Invariants through the Universal Quantum R-Matrix

In temporal gauge A_{0}=0 the 3d Chern-Simons theory acquires quadratic action and an ultralocal propagator. This directly implies a 2d R-matrix representation for the correlators of Wilson lines (knot invariants), where only the crossing points of the contours projection on the xy plane contribute. Though the theory is quadratic, P-exponents remain non-trivial operators and R-factors are easier to guess then derive. We show that the topological invariants arise if additional flag structure (xy plane and an y line in it) is introduced, R is the universal quantum R-matrix and turning points contribute the "enhancement" factors q^{\rho}.Comment: 27 pages, 17 figure

Reaching collective immunity for COVID-19: an estimate with a heterogeneous model based on the data for Italy

Abstract Background At the current stage of COVID-19 pandemic, forecasts become particularly important regarding the possibility that the total incidence could reach the level where the disease stops spreading because a considerable portion of the population has become immune and collective immunity could be reached. Such forecasts are valuable because the currently undertaken restrictive measures prevent mass morbidity but do not result in the development of a robust collective immunity. Thus, in the absence of efficient vaccines and medical treatments, lifting restrictive measures carries the risk that a second wave of the epidemic could occur. Methods We developed a heterogeneous model of COVID-19 dynamics. The model accounted for the differences in the infection risk across subpopulations, particularly the age-depended susceptibility to the disease. Based on this model, an equation for the minimal number of infections was calculated as a condition for the epidemic to start declining. The basic reproductive number of 2.5 was used for the disease spread without restrictions. The model was applied to COVID-19 data from Italy. Findings We found that the heterogeneous model of epidemic dynamics yielded a lower proportion, compared to a homogeneous model, for the minimal incidence needed for the epidemic to stop. When applied to the data for Italy, the model yielded a more optimistic assessment of the minimum total incidence needed to reach collective immunity: 43% versus 60% estimated with a homogeneous model. Interpretation Because of the high heterogeneity of COVID-19 infection risk across the different age groups, with a higher susceptibility for the elderly, homogeneous models overestimate the level of collective immunity needed for the disease to stop spreading. This inaccuracy can be corrected by the homogeneous model introduced here. To improve the estimate even further additional factors should be considered that contribute to heterogeneity, including social and professional activity, gender and individual resistance to the pathogen. Funding This work was supported by a grant from the Ministry of Education and Science of the Russian Federation, a unique project identifier RFMEFI60819X0278