Current Trends in Improving of Artificial Joints Design and Technologies for Their Arthroplasty

There is a global tendency to rejuvenate joint diseases, and serious diseases such as arthrosis and arthritis develop in 90% of people over 55 years of age. They are accompanied by degradation of cartilage, joint deformities and persistent pain, which leads to limited mobility and a significant deterioration in the quality of life of patients. For the treatment of these diseases in the late stages, depending on the indications, various methods are used, the most radical of which are methods of joint arthroplasty and, in particular, total arthroplasty. Currently, total arthroplasty is one of the most effective and high-quality surgical operations at the relevant medical indications. However, complications may also arise after it, leading, inter alia, to the need for repeated surgical intervention. In order to minimize the likelihood of complications, the artificial joints used in total arthroplasty and the technology of their fabrication are constantly being improved, which leads to the emergence of new designs and methods for their integration with living tissues. At the same time, at the moment, the improvement of traditional designs and production technologies has almost reached the top of their art, and their further improvements can be insignificantly or are associated with the use of the most up-to-day technologies, allowing for friction couples with low tribological properties to provide for them high ones, for example, gradient increase hardness in the couple titanium alloy on titanium alloy. This paper presents the current state of traditional technical means and technologies for joint arthroplasty. The main attention is paid to the analysis of the latest technologies in the field of joint arthroplasty, such as osseointegration of artificial joints, the improvement of materials with the property of osteoimmunomodulation, the improvement of joint arthroplasty technologies based on the modeling of dynamic osteosynthesis, as well as the identification of possible unconventional designs of artificial joints that contribute to these technologies, predictive assessment of areas for technologies improvement.DFG, 414044773, Open Access Publizieren 2019 - 2020 / Technische Universität Berli

Structural and electronic properties of β-NaYF4 and β-NaYF4:Ce3+

AP is indebted for a financial support provided by Scientific Research Project grant for Students and Young Researchers Nr. SJZ/2017/3 sponsored at the Institute of Solid State Physics, University of Latvia , while AIP is thankful for the financial support from Latvian Research Council lzp-2018/1-0214 .In this work, the density functional theory approach with linear combination of atomic orbitals (LCAO) as implemented in the CRYSTAL17 computer code is applied to hexagonal β-NaYF4, located in three possible space groups of this compound: P6‾, P63/m and P6‾ 2 m. First, the disordered crystalline structure of NaYF4 was modelled in a large supercell containing 108 atoms. In order to obtain better agreement with the experimental data, we used several different exchange-correlation functionals. Basic properties, such as lattice constant, band gap and total energies were calculated and compared for all three space groups and three exchange-correlation functionals - HSE06, PWGGA and PWGGA+13%HF. It was found that for all three functionals, the minimum of total energy corresponds to P6‾ space group. Secondly, in order to study the effects associated with the Ce3+ impurity and the F center (radiation defect), the P6‾ β-NaYF4 structure with the F center and Ce3+ or with both was carefully modelled. Taking into account that fluorine atoms have different nearest neighbours, several types of fluorine vacancies were simulated and an appropriate formation energies were determined. Finally, the effects of Ce3+ ion substitution of Y ions in different positions as well as formation of Ce3+, the F center defect pairs were also studied and an appropriate incorporation energies were calculated.University of Latvia; Latvian Research Council lzp-2018/1-0214; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART²https://www.sciencedirect.com/science/article/pii/S0925346719307499?via%3Dihu

Uncertain Curve Simplification

We study the problem of polygonal curve simplification under uncertainty, where instead of a sequence of exact points, each uncertain point is represented by a region, which contains the (unknown) true location of the vertex. The regions we consider are disks, line segments, convex polygons, and discrete sets of points. We are interested in finding the shortest subsequence of uncertain points such that no matter what the true location of each uncertain point is, the resulting polygonal curve is a valid simplification of the original polygonal curve under the Hausdorff or the Fr\'echet distance. For both these distance measures, we present polynomial-time algorithms for this problem.Comment: 25 pages, 5 figure

Nove interdisciplinarne raziskave neolitskih in eneolitskih najdišč na območju Spodnje Volge

The Neolithic and Eneolithic sites in the Low Volga River region have been poorly investigated in comparison with other territories due to a small number of excavated sites. On the Algay site and the Oroshaemoe I settlement there is evidence of the earliest appearance of Neolithic pottery and the first sign of domestication in the Eneolithic period within the Volgo-Ural territory. Archaeological, lithological, grain-size analyses, mineralogical-geochemical methods and radiocarbon dating of cultural deposits have been applied to reconstruct the palaeoenvironment in the Holocene in this area. The results show that the landscape-climatic conditions in the steppe area of the Lower Volga basin strongly affected the development and adaptation of ancient societies.Neolitska in eneolitska najdišča na območju Spodnje Volge so bila v preteklosti zaradi maloštevilnih izkopavanj slabše raziskana v primerjavi z drugimi regijami. Na najdiščih Algay in Oroshaemoe I smo odkrili najstarejši pojav neolitske lončenine in prve znake domestikacije v obdobju eneolitika na območju Volge in Urala. Za rekonstruiranje holocenskega paleookolja na tem območju smo uporabili arheološke, litološke metode, analize velikosti zrn, mineraloško-geokemične metode in radiokarbonsko datiranje kulturnih ostalin. Rezultati kažejo, da so okoljski in klimatski pogoji na območju stepe ob Spodnji Volgi močno vplivali na razvoj in prilagoditve preteklih družb

ONE-DIMENSIONAL BIOLOGICAL MODEL OF SYNOVIAL JOINTS REGENERATIVE REHABILITATION IN OSTEOARTHRITIS

This work is devoted to the study of a one-dimensional phenomenological model of a focal defect regenerative rehabilitation in the articular cartilage. The model is based on six differential equations in partial derivatives of the “Diffusion-Reaction” type, which was previously used by a number of authors to study cellular processes in various tissues under cell therapy conditions. To take into account the influence of moderate mechanical stimulation of immature tissue, an indirect approach was used, as a result of which some model parameters that directly affect cell proliferation and differentiation were varied considering experimental data. The results of  the model study  show that moderate stimulation of immature tissue in the early stages of repair the focal articular cartilage defect under conditions of cell therapy leads to an intensification of regenerative processes in the tissue and promotes more rapid formation of the extracellular matrix

Generator analog and digital signals

In this article, we will focus on the creation of printed circuit boards for electronic devices. In fact, a whole science with a lot of nuances, calculations, etc. In this article, we will only consider the tracing process for example emulator digital and analog signals

Demography of the Crimean Tatar Population of the 16th – 18th Centuries (According to the Materials of the Necropolis near the Village of Fontan)

Introduction. The article discusses the demographic characteristics of the population of the Crimean Tatar village of Karmysh-Kelechi of the 16th – 18th centuries based on the materials of Fontan-1 burial ground. Methods and materials. Research procedures included the construction of mortality tables that characterize the sequence of extinction of a certain generation of people or general patterns of changes in mortality for cohorts of the population with a similar order of extinction. The mortality tables contain various demographic indicators that were analyzed during the study. Results. As a result of the analysis, the author has found out the main demographic indicators of this population. These include a high mortality rate of children from newborn to 4 years with a predominance of children under 1 year; a slight predominance of the male population over the female; the average age of death for children was 20.6; the average age of death of the adult population – 36.5.; men lived three years longer than women. Moreover, in women, two peaks of mortality occur during the childbearing period and are probably associated with the stress that accompanies the female body during pregnancy and childbirth. The distribution of the male mortality reflects the natural process of aging and death. It is possible that the high infant mortality rate, as well as the lower average age of death, may be due to adverse external factors. The comparative analysis of the demographic indicators of the population who left Fountain-1 burial ground with synchronous groups shows that they all correspond to the indicators of populations of the Early Modern times and do not get out of the general context

The Material and Technical Basis of Corporate Enterprises Reproduction Organizing Under a Process of Joint Stock Capital Changing Организация управления воспроизводством материально-технической базы корпоративных предприятий в условиях изменений акционерного капитала

We prove the relevance of consolidated review cycle management transformations equity and loop playback logistics corporate enterprise. We proved the appropriateness of use synergy elements of logistics participants transformation processes as a factor in the decision to implement agreements on mergers and acquisitions to use. The ways of bringing synergy to the parameters of the methods of valuation corporations while merging and acquisitions.<br>Доказана уместность консолидированного рассмотрения цикла управления трансформационными изменениями акционерного капитала и контура воспроизводства материально-технической базы корпоративного предприятия. Предложено в качестве фактора принятия решения о реализации соглашений по слияниям и поглощениям использовать наличие синергии элементов материально-технической базы участников трансформационных процессов. Определены направления имплементации параметров данной синергии к методам оценки стоимости корпораций при слияниях и поглощениях