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In present work the parametric interaction of two optical waves presented by their slowly varying amplitude functions A1(z) and A2(z) in isotropic nonlinear medium is investigated. The corresponding system of nonlinear amplitude differential equations describes the processes of third-harmonic generation and THz generation in femtosecond region. It is found analytical solution of this system, characterizing the periodic exchange of energy between the two waves. The obtained result can be used for investigating different parametric processes in nonlinear dielectric medium, depending on the value of the wavenumber mismatch Dk. These effects are directly related to modern communication systems and optical sensors.
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In this paper, we unify the study of the geodesics in the Bondi-Gold-Hoyle universe model. Thus, we obtain analytical solutions of the geodesic equations which describe the motion of space-like, time-like and light-like particles in the considered model. In the case of light-like geodesics, we get the solutions obtained by Marcheva & Ivanov, 2017.
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A concise review of the effect of gamma radiation on the living organisms is presented. The medical topics of the problem are elucidated and commented.
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The healing power of many plants has been known since ancient times and it is used until nowadays all over the world. The herbs Calendula officinalis L. and Matricaria chamomilla L. are among the most commonly used herbs. The article mentions the biologically active substances and their usage in folk medicine. The content of the radionuclides in both plants and the soil, near the root system of the samples collected in June and July 2016 from the region of Yagnillo village, Varna district, has been investigated. Flowers and soil are cleaned from impurities, dried and levigated in fine powder. Gamma-spectrometric analysis was performed on the prepared samples. A low-frequency gamma-spectrometer set up by a Ge (Li) detector with multilayer protection is used. The collection of gamma-spectra was done for 86,400 s. A specialized software for gamma-spectra – ANGES – was used for their processing. The activities and specific activities of the detected natural radionuclides from the Uranium-radionuclide and Toric families are calculated. The transfer from soil to plant has been calculated. A comparative analysis of the radionuclides content in the plants and the soils on which they were grown has been made. The comparison shows qualitative and quantitative compatibility with the radionuclides found.
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Photonisotropic materials can be divided into two main groups: inorganic and organic materials. Polymers containing organic dyes are the subject of multiple studies in both areas of physics and medicine. Optical storage in azobenzene-containing polymers is based on the alignment of the polymer chains initiated by the reorientation and ordering of the azobenzene groups. This process requires considerably high recording energies but elevated temperature eases the mobility of the molecules thus making possible their reorientation by lower light intensities. On the other hand, an attractive approach is to use light, both to report on and control signaling proteins in cells, because light can probe cells in real time with minimal damage. Of particular interest is the development of chemically engineered proteins that are directly sensitive to light. The aim of this work is to present some physical factors influencing the azobenzene polymers properties used in various fields of science.
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There are many substances in extra virgin olive oil (EVOO), of which many have a beneficial effect. One of the most interesting substances in EVOO is Oleocanthal. This substance is first recognised in 2005 and can only be found in EVOO. Under further investigations it was proven that in vitro Oleocanthal has an anti-inflammatory effect comparable to Ibuprofen. This is due to the fact that it is an inhibitor of cyclooxygenase. It is able to form prostanoids, including thromboxane, which takes part in formation of thrombosis, and prostaglandins including prostacyclin, which prevent the formation of the platelet plug during blood clotting and acts as a vasodilator. The quality control of an EVOO is very important, because most often refined oils such as olive-pomace oil, seed oils or synthetic oils are used. In some cases, this may lead to serious health problems after consumption. Such an incident happened 1981 in Spain (Spanish toxic Oil syndrome) where 20000 people were affected from which 330 died from aniline intoxication. Optical techniques are ideal for this purpose because they are simple, cost-effective, rapid and non-destructive. Fluorescence spectroscopy has different applications: detection of adulteration, geographic region, quantification of fluorescent components, monitoring of photo-oxidation and thermal and assessment of quality changes of olive oil during storage.
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Focal infection is a present hidden infection inside the body that is not strong enough to cause symptoms and most often patients don’t know about its presence. By the physiological paths the organism can suppress it, but when a decrease in the immune protection occurs (virus, stress, fatigue) the focus of infection overcomes local protection and affects by the connective tissue distant organs and systems (heart, kidneys, joints, eyes, skin). Focal infection can be the genuine cause for some diseases (ear infections, pyelonephritis, arthritis, alopecia areata) or aggravation factor for others. Very often even doctors consider directing patients for focal infection diagnostics, when have run out of therapeutic possibilities. That’s why focal infection is a major medical problem and both doctors and patients pay much more attention. Infrared thermography is a contemporary method for non-contact thermodiagnostics and for short time the whole body temperature can be registered as thermal pictures. This happens by infrared camera that is highly sensitive and hi-tech technology that registers the infrared spectrum radiating from the object of surveillance. After a thorough computer analysis, the different foci and their activity can be differentiated. As a contemporary method for focal diagnostics infrared thermography gives guidelines for finding focal infection in the whole body in unclarified cases. Moreover, it’s a method that distinguishes with detailed information, possibility for precise software analysis and direct digital data transfer that’s why infrared thermography has its important place in the diagnostics of focal infection.
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In 2017/2018 school year in the new curriculum of the subject “Protection of Population and Infrastructure” for the first time will appear discipline “Applied Physics”. It focuses on practical-applied knowledge in physics and its application in different situations, sometimes in extreme conditions.Under the available state of the University‘s material base, non-standard methods should be done to students and learners and to find ways to apply their knowledge and skills in various non-standard situations, sometimes even non-traditional.In the lab, each student will conduct his/her own experiment in which he she will apply his knowledge both in physics and related subjects.
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In the present study, some electrical properties of polylactic acid (PLA) composite films with different percentages of MgO – 0 wt%, 2 wt%, 4 wt% and 8 wt% were investigated. Composite films were prepared using a Brabender Plastograph EC Plus blender under controlled electric heating for 5 minutes at 190 ° C. The films obtained were charged by the corona discharge method using a tri-electrode system for 1 minute under room conditions. Positive or negative 5kV voltage was applied to the corona electrode. 1 kV voltage of the same polarity as that of the corona electrode was applied to the grid. The surface potential of the charged samples was measured by the vibrating electrode method with compensation. The time dependencies of surface potential were investigated. The results obtained show a significant change in the electret behavior of PLA composite films after insertion of MgO particles with different concentration. Some dielectric and impedance characteristics of composite films were also studied. Dielectric permittivity was calculated. The results obtained show a change in dielectric permittivity by increasing the concentration of the inserted MgO particles in the PLA matrix.
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mushrooms; isothermal drying; mathematical modelEleven kinds of mathematical models were used to obtained moisture data. From obtained results, the semi-theoretical models chosen in this work proved to be quite good to describe the drying behavior of isothermal drying. In the experiment, Modified Henderson and Pabis model was most appropriate for fitting MR − t curve of isothermal drying of hot-air drying, its correlation coefficients is above 0.999; for chi-square is below 0.0075; for root mean square error is below 0.0077.
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The article examines the main reasons for lack of sufficient staff in the education system. Shown are results of several studies in this direction and the views of teachers from across Europe on activities that would be successful in combating the crisis of European education.According to the authors, in order to overcome the problem, the economic and general social status of the Bulgarian teacher must be increased, which can be achieved by raising wages in the sector, by qualification of teachers and introducing systems for career development, for differentiated pay work tied to pupils’ results and for teacher rewards.
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Młodzi wcale nie muszą mieć dziś lepiej. I to jest powód narastającej fali antyestablishmentowej, której politycznym wymiarem jest Kukiz’15, PiS czy Ruch Narodowy. Ich siła zrodziła się z rozczarowania upadkiem złudzenia, że porażkę rodziców można będzie przesłonić sukcesem dzieci.
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The communication strategies are considered in the context of the current needs of the theory and practice of the Bulgarian language education – development of communicative speech competence which is understood as acquiring knowledge and developing skills required to meet the communication needs of the students in personal and social terms leading them to achieve personal fulfillment.
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The paper explicates a comparative interpretative reading of D. Boyadjiev’s poem “Elegy”, as well as D. Debelyanov’s poem “I Want to Remember You Like That”. The art imagery of the poetic text is considered through the prism of memory as a specific being, as a sign reality, embodying the act of consciousness, which considers that the found Meaning is always contradictory and immanent when connected to experience and realization of Love.
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This article provides information on a pedagogical experiment in which the computer presentation stays as a visual support for a diverse teaching with innovative approach. The key milestones include: subject, object, aim, objectives, hypothesis, scope, criteria, indicators, the study methodology and achieved results.
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The article presents some results from researching the cultural heritage of the Bulgarian communities in Central and Western Europe from 1991 to 2015. Empirical data on the use of distance learning in Bulgarian schools abroad are collected through electronic survey and discussion meetings with teachers. Based on the teachers’ suggestions Virtual Information Center has been created. The aim is to support the process to meet the communication and cultural needs of Bulgarians who live in our communities abroad and exchange of best pedagogical practices in a virtual educational environment.
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