Search

In the paper such subclass of string graphs as intersection graphs of closed polygonal chains (class of CPC-graphs) was considered, necessary conditions for belonging to that class, forbidden subgraphs and operations with graphs which preserve belonging to the CPC class were found. Considered question about the existence of k-regular CPC-graphs, particularly, pairs (k, n), such that there exists k-regular CPC-graph on n vertexes were found, proved that there are infinitely many k-regular CPC-graphs for any k ∈ N, estimations for the number of k, such that k-regular graph on n vertexes exists, were given. Algorithmic questions in the class of CPC-graphs were investigated. It was proved that independent and dominating set problems, coloring problem and the problem about maximal cycle are NP-hard in the class of CPC-graphs, and problem of recognition of the CPC-graphs belongs to the PSPACE class.

The article touches upon the current problems of pollution of the oceans. The significant role of the ecosystem, fauna and flora of the World Ocean in the formation of climate on the planet are noted. The oceans, as a powerful regulator of climate and weather, plays an extremely important role in the development of life on Earth, controls oxygen balance, provides food, biological and mineral resources, etc. One of the global tasks that humanity needs to solve is the reduction (prevention) of negative impacts on aquatic ecosystems. Especially detrimental to the ecology of the oceans are drilling works, production and transportation of liquid hydrocarbons by tankers, because in the process of work there takes place the water surface pollution producing a thin oil film. With sewage waters from the industrial enterprises a huge amount of toxic heavy metal compounds enter the World Ocean. The source of pollution is the ballast water from vessels, which serve to ensure the balance and stability of the vessels. At present, man has already faced such problems as the greenhouse effect, warming trend on Earth, melting of ice at the North Pole and South Pole, rising sea levels above 3 m, reducing biological productivity of the World Ocean, etc. The invasion of alien organisms, including pathogenic ones for the ecosystem and humans, is considered in detail. The standards of the International Maritime Organization (IMO) for ballast discharged water have been given. Existing methods of ballast water treatment are described in accordance with the requirements of the International Convention on control and management of ships' ballast water and sediments 2004. The possible ways of combating pollution of ocean waters are proposed as an important element for protection of the ecosystem of the World Ocean.

In modern economic conditions, the issue of improving the efficiency of mining enterprises is very relevant. One of the key processes isdrilling and blasting operations (DBO), which determine the efficiency of the entire complex of mining operations. One of the main methods of controlling the explosion energy is the diameter of the blast wells. According to the recommendations of prof. B N Kutuzov the diameter of blast wells is correlated with the fracturing and strength of the exploding rocks. With increasing blockage and rock strength to achieve the required quality of explosive crushing preference is given to drilling equipment with a small diameter of wells. By blasting of high ledges, especially large-block rocks with a strength coefficient of more than 15 on the M M Protodyakonov scale; the use of high-performance drilling equipment for drilling small-diameter blast wells is difficult. This is due to the fact that the calculated value of the resistance line along sole (RLAS) does not pass the safety condition for drilling the first row of wells. In this regard, the paper proposes and justifies the use of extensions of the lower parts of wells using mechanical expanders.

By development marble deposits in mining operations one of the main technological processes, that ensures minimal losses and dilution with maximum output of commercial products is the process of preparing rocks for excavation. Marble extracted for the production of microcalcite is prepared for excavation by drilling and blasting at most mining enterprises. This inevitably leads to overgrinding in the charging chamber zone and, as a result, to a decreasing in quality indicators (yellowness and whiteness), significant losses of minerals (0–20 mm fraction) up to 30% and a low percentage of high-grade crushed stone in the commodity balance. The paper considers a variant of improving the production technology on the example of the Eleninsky marble Deposit (Chelyabinsk region) by using of heavy-class hydrohammers, which allows to increase the efficiency and completeness of the development of balance reserves by reducing by 5–10% overgrinding and increasing output of a commercial product high grades (40–200 mm).

Increase in energy efficiency of construction allows reducing costs of technical operation of parks of the equipment and increasing construction energy saving level in general. To achieve these goals, it is offered to apply modern methods of the organization and works, to use the hi-tech construction equipment, and also to form an optimum set of mechanization for construction and installation works. A criterion of optimization is the cost of work. In definition of performance data of the car at the enterprise, its energy efficiency is taken into account, the options are compared, and the optimal set of cars is formed. During the solution of the task, conclusions were formulated, showing that ecological planning and steering together with energy audit on the construction site allow more rational formation of parks of cars, improving ecological component and quality of construction works.

An approach to the analysis of the quality of the recovered post detector low-contrast images formed in the rear vision systems in the presence of complex background conditions by using robust algorithms. A choice of the composition of the characteristics of two-dimensional functions as an image invariants, which allows to assess the complexity and quality of the reconstructed images. To assess the complexity of the spatial structure of images is proposed to use two-dimensional variation Kronrod. Examples of the analysis of the results of processing low-contrast images formed robust filtering algorithm.

In the presented article there will be discussed measures which allow to lower expenses for the maintenance of the machinery and which contribute to the increase of energy saving in general. To achieve these goals, it is proposed to apply modern methods of organizing and operation works, to use high-tech construction equipment, and also to form an optimal mechanization complex of building and construction works. The optimization criterion is the cost of work. When determining costs for the operation of construction machinery at the site, we take into account their energy efficiency, compare the options and manage the most efficient fleet of construction equipment. In the course of meeting the task, there were drawn conclusions which demonstrate that an integrated approach to the formation of machinery parks on the construction site allows to use the available resources more rationally, in order to improve the environmental component and improve the quality of construction work.

Electron paramagnetic resonance (EPR) studies of Er3+ of single-crystal KY(WO4)2 have been carried out at X-band frequencies over a temperature range from 4.2 to 300 K. The main x- and z-axes of the g-tensor in the ac plane do not coincide with the crystallographic a-and c-axes, while the y- and b-axes are parallel. The EPR spectrum is characterized by a strong anisotropy of the g-factors (gz = 13.25 ± 0.05, gx = 0 ± 0.1, gy = 3.378 ± 0.005) and of the hyperfine interaction parameters (Az = −469 ± 3, Ax = 0 ± 3.5, Ay = −120.75 ± 0.8 in 10−4 cm−1). The temperature dependence of the g-factors is caused by an anharmonic part of the spin–phonon Hamiltonian as well as by a rotational contribution to this Hamiltonian. A spin–lattice relaxation is shown to result from two Orbach processes through the first and second excited levels of an electronic spectrum.

The study presents the remote results of surgical treatment of 329 patients with cancer of gastroesophageal localization. Three 3-year survival rate is 37.1%, the 5-year survival rate is 26.2%. Prognosis after the surgery depends primarily on the extent of the tumour spread. In all types of surgeries the survival rate of patients without lymph nodes metastasis is twice as high as that of patients with metastatic spread to lymph nodes. The amount of the affected lymph nodes does not affect overall as well as relapse-free survival. Combined and palliative resections may procedure the 5-year survival rate at the level of only 10-15%.

Learning objectives Background Findings and procedure details Conclusion Personal information References, Learning objectives: To study ultrasound criteria Fournier's gangrene...

Despite some progress in early detection and treatment, gastric cancer remains one of the most complex healthcare and socioeconomic problems. Belarus is among the countries with the highest incidence rate of cancer with this localization. In 2013, according to the Belarusian National Cancer Registry, 2888 new cases of gastric cancer were registered, with peak incidence observed in the 75-79 age group; men were affected more frequently than women at a ratio of 2.4:1. In 2013 in Belarus the five-year survival rate was 23.5%; and for patients with clinical stage I and II – it was 50.3% [1]. A retrospective analysis was conducted on 8466 gastric cancer patients from different age groups treated in Minsk City Clinical Oncological Hospital from 1998 to 2013. Of these, 72 (0.85%) patients were under the age of 30, 72.2% of which were diagnosed with clinical stage IV cancer. Radical surgery was performed on 17 patients (24.0%), palliative on 11 (15.0%) and symptomatic on 22 (31.0%). Out of these 72 patients, 75% had a three-year survival rate, while 62% had five-year survival rate. Overall survival rate after palliative surgery did not exceed two years. Without specific antitumor treatment all patients under the age of 30 with advanced stomach cancer, died within a year, while adjuvant chemotherapy increased the life span by not more than a year.