White staphylococcus spp. is the common name for staphylococci that do not form a golden pigment. It causes and complicates the course of many inflammatory processes in various organs and tissues of humans and animals. In particular, in dairy cattle breeding, white staphylococcus is the main cause of serous and serous-catarrhal mastitis. Low efficiency in the treatment of staphylococcal mastitis is due to the resistance of the pathogen to antibiotics. Accordingly, the use of chemotherapeutic drugs for mastitis without prior determination of the sensitivity of isolated strains of pathogenic microorganisms to antibiotics leads to double economic damage.

The article presents epizootological and clinicomorphological data on the course of diplococcus septicus infection of piglets in private pig-growing farms of Kotayk Region, Republic of Armenia. According to the results of the studies, the main reasons for the appearance of the mentioned infection among piglets is the failure in observing zoohygienic and veterinary-sanitary rules throughout housing of animals, as well as the lack of immunoprophylactic measures. Timely vaccination of gestating sows provides natural lactogenic immunity in piglets, preventing significant economic losses resulted from the death of sick animals and the expenses spent for therapeutic measures.

Features of the simultaneous action of longitudinal and transverse ultrasonic vibrations in the quartz crystal on the parameters of reflected X-rays are studied. It is shown that this action results both in the X-ray acoustic conversion effect, which is an increase in the intensity of radiation diffracted by the crystal at the excitation of transverse vibrations with linear polarization, and in the broadening of the rocking curve, which is due to the formation of a standing wave in the crystal at longitudinal vibrations. It is demonstrated for the first time that several key parameters of X-rays can be simultaneously controlled using a single crystal. Transverse vibrations make it possible to vary the intensity of diffracted radiation, and longitudinal vibrations allow controllable angular rearrangement of the X-ray beam diffracted by the crystal.

We investigate the radiation from a bunch of relativistic electrons moving along the cylindrical waveguide axis, assuming that the waveguide is partially loaded by a medium with periodic dielectric permittivity and magnetic permeability. The spectral distribution of the radiation energy flux through the cross section of the waveguide is studied at large distances from the medium. The analysis is based on the corresponding exact solution of Maxwell equations for the case of a single electron moving along the waveguide axis. The results of numerical calculations are presented in the special case of layered medium consisting of a finite number of dielectric plates separated by vacuum gaps. We show that under certain conditions on the problem parameters the quasi-coherent Cherenkov radiation generated by the electron bunch inside the plates is self-amplified at certain waveguide modes. A visual explanation of this phenomenon is provided that reproduces the main features to rather good accuracy.

The diffraction of an electromagnetic wave from a round hole on an opaque screen is studied when there is no vacuum on the opposite sides of the screen, as is usually considered, but on one side there is a refractive medium and on the other—vacuum. The diffraction peculiarities due to the fact that the medium into which the wave penetrates from the vacuum have a refractive index different from one are revealed. The case of diffraction in an anisotropic medium with the property of birefringence is also considered.

The mechanical deformations in the quartz X-ray acoustic element arising by the excitation of resonant thickness ultrasound oscillations are investigated experimentally and theoretically. Experiments were carried out using the X-ray topography and double-crystal diffractometry, and theoretical computations were performed using the mathematical modeling by the finite element method. It follows from the computations that the mechanical deformation arising in the resonator as a result of the excitation of thickness variations, is strongly stratified and represents a series of maxima, the distance between which depends on the crystallographic direction. The large number of nodes and antinodes of the oscillations directly depends on the resonant frequency of the X-ray acoustic element. The obtained experimental results are in good agreement with theoretical computations.

X-ray multiple-wave interaction in a paratellurite crystal (TeO2) under modulation of the crystal lattice by low-frequency ultrasonic vibrations is studied. The use of such vibrations enables accurate scanning or tuning of the multiple-wave region of X-ray interaction.

If the discharge current into a plasma contains direct and variable components, the plasma develops wavelike acoustic instabilities and eventually becomes an acoustoplasmа. Such instabilities lead to bistability, multistability, and hysteresis phenomena of the current–voltage characteristics, causing abrupt changes in the state of the plasma medium. These changes can be imagined as phase transitions and described using catastrophe theory. In the present study, the experimental plasma data are approximated by the equations of catastrophes. After reducing the catastrophe equation to canonical form, the points of possible phase transitions are determined. The phase transition coordinates are then converted to coordinates in the experimental system by inverse transformations. In this way, we determine the points of possible phase transitions in a real experiment. Finally, the parameter changes in an acoustoplasma discharge are obtained by solving incorrectly posed inverse problems. The inverse problem of the experimental data is solved at each current time. Within the neighborhoods of singular points, the incorrectly posed inverse problems are solved by the theory of catastrophes. The proposed methods are applicable to various fields of science and technology.

We investigate the radiation of surface polaritons by a charged particle rotating around a dielectric waveguide. The general case is considered when the waveguide is immersed in a homogeneous medium. For the evaluation of the corresponding electromagnetic fields the electromagnetic Green tensor is used. A formula is derived for the spectral distribution of the radiation intensity for surface-type modes. It is shown that the corresponding waves are radiated on the eigenmodes of the dielectric cylinder. We demonstrate that the number of radiated quanta for surface polaritons of a given harmonic can be essentially larger than that for guiding modes of the cylinder. The geometry under consideration is of interest from the point of view of generation and transmitting of waves in waveguides, a subject which is of considerable practical importance in microwave engineering and optical fiber communications.

Forward transition radiation from relativistic electrons is investigated in an ultrasonic superlattice excited in a finite thickness plate by two acoustic waves. In the quasi-classical approximation formulae are derived for the vector potential of the electromagnetic field and for the spectral-angular distribution of the radiation intensity. Zone structures appear in the plate, which makes it possible (by an appropriate choice of the frequencies of the two acoustic waves) to control the spectral-angular distribution of the radiation through changes in the parameters of the medium. The acoustic waves generate new resonance peaks in the spectral and angular distribution of the radiation intensity. The heights of the peaks can be tuned by choosing the parameters of the acoustic waves. Numerical examples are presented for a plate of fused quartz.

The radiation of electromagnetic surface waves is investigated for a charged particle rotating around a dielectric cylinder immersed into a homogeneous medium. Formulae are provided for the corresponding electric and magnetic fields and for the radiation intensity. It is shown that the surface waves are radiated on the eigenmodes of the cylindrical waveguide.

We investigate the radiation from a charge rotating around conductors with cylindrical symmetry. First the problem is considered with a charge rotating around a conducting cylinder immersed in a homogeneous medium. The surface charge and current densities induced on the cylinder surface are evaluated. A formula is derived for the spectral-angular density of the radiation intensity. In the second part, we study the radiation for a charge rotating around a diffraction grating on a cylindrical surface with metallic strips parallel to the cylinder axis. The effect of the grating on the radiation intensity is approximated by the surface currents induced on the strips by the field of the rotating charge. The expressions are derived for the electric and magnetic fields and for the angular density of the radiation intensity on a given harmonic. We show that the interference between the synchrotron and Smith-Purcell radiations may lead to interesting features. In particular, the behavior of the radiation intensity on large harmonics can be essentially different from that for a charge rotating in the vacuum or around a solid cylinder. Unlike to these limiting cases, for the geometry of diffraction grating the radiation intensity on higher harmonics does not vanish for small angles with respect to the cylinder axis. For given characteristics of the charge, by the choice of the parameters of the diffraction grating, one can have highly directional radiation near the normal to the plane of the charge rotation. With decreasing energy, the relative contribution of the synchrotron radiation decreases and the Smith-Purcell part is dominant.

We investigate combined effects of nontrivial topology, induced by a cosmic string, and boundaries on the fermionic condensate and the vacuum expectation value (VEV) of the energy-momentum tensor for a massive fermionic field. As geometry of boundaries we consider two plates perpendicular to the string axis on which the field is constrained by the MIT bag boundary condition. By using the Abel-Plana type summation formula, the VEVs in the region between the plates are decomposed into the boundary-free and boundary-induced contributions for general case of the planar angle deficit. The boundary-induced parts in both the fermionic condensate and the energy-momentum tensor vanish on the cosmic string. Fermionic condensate is positive near the string and negative al large distances, whereas the vacuum energy density is negative everywhere. The radial stress is equal to the energy density. For a massless field, the boundary-induced contribution in the VEV of the energy-momentum tensor is different from zero in the region between the plates only and it does not depend on the coordinate along the string axis. In the region between the plates and at large distances from the string, the decay of the topological part is exponential for both massive and massless fields. This behavior is in contrast to that for the VEV of the energy-momentum tensor in the boundary-free geometry with the power law decay for a massless field. The vacuum pressure on the plates is inhomogeneous and vanishes at the location of the string. The corresponding Casimir forces are attractive.

We investigate the spectral-angular distribution for the radiation emitted by a point charge moving along a helical trajectory inside a cylindrical grating with conducting strips. Two types of the radiation processes are realized: undulator and Smith–Purcell radiations. Their relative contributions to the total radiation intensity are discussed in various asymptotic regions of the parameters describing the diffraction grating and for large harmonics. The region of the parameters is specified for which the interference effects between the undulator and Smith–Purcell radiations are essential.

The spectra of X-ray diffraction from the reflecting atomic plane (1 0 1̅ 1) of a quartz single crystal are studied in Laue geometry under the action of temperature gradient on a BDER-KI-11K spectrometer with a resolution of 300 eV on the Am241 line of 17.74 keV. The temperature gradient leads to an increase in the intensity of the diffracted beam depending on the heating temperature. It is shown that the intensity of X-ray diffraction in Laue geometry may increase at a temperature gradient of 250°C/cm by two orders of magnitude in comparison with the uniform temperature state of the crystal. The rocking curve of the reflected beam is obtained at a fixed observation angle of 6° and a specified temperature gradient. It is demonstrated that the intensity of the reflected beam increases with increasing temperature gradient (to a certain value), while the spectral width of the reflection line remains constant and is governed by the energy resolution of the spectrometer. A further growth in the temperature gradient leads to an increase in the spectral width of the reflection line with decreasing intensity of the reflected beam.

We investigate the transition radiation on a periodically deformed interface between two dielectric media. Under the assumption that the dielectric permittivities of the media are close, a formula is derived for the spectral-angular distribution of the radiated energy in the general case of a nonstatic profile function for the separating boundary. In particular, the latter includes the case of surface waves propagating along the boundary. The numerical examples are given for triangular grating and for sinusoidal profile. We show that instead of a single peak in the backward transition radiation on a flat interface, for periodic interface one has a set of peaks. The number and the locations of the peaks depend on the incidence angle of the charge and on the period of the interface. The conditions are specified for their appearance.

The Si/Ge heterostructure, the active area of which is composed of the Ge quantum dots (QD), is investigated theoretically. The high density of the Ge QDs array cannot be the dominant feature in the choice of an adequate model that can explain the experimentally observed increase in the intensity of luminescence. In the basis of such model the conditions are laid that increase the oscillator strength of exciton due to the 'retraction' of electronic states into the Ge QD core.

Purpose: Tularemia is a bacterial zoonosis caused by Francisella tularensis, designated an especially dangerous pathogen. Inhalation of as few as ten organisms can cause disease. Tularemia is endemic to Armenia. Methods & Materials: We have conducted a retrospective descriptive study of epidemiologic, clinical, diagnostic and treatment aspects of tularemia in Armenia among patients hospitalized in "NORK" Infectious Hospital from 2000–2015. Diagnosis was confirmed by an agglutination reaction and the clinical-epidemiology history of the patients. Results: From 2000-2015 a total of 57 cases of tularemia were reported in Armenia. Of these, 84.2% were male and 78.9% were from rural areas. Distribution of age groups were: ≤18–24.6%, 19-30–54.4%, 31-44–14.01%, ≥45–7.0%. The most common symptoms include: fatigue (n=52, 91%), fever (n=45, 78.9%), pharyngitis (n=40, 70.2%), headache (n=27, 47.4%), hepatomegaly (n=5, 8.8%), and splenomegaly (n=2, 3.5%). The average hospitalization stay was 35.7 days. The most frequent clinical forms were bubonic (n=28, 49.1%), oropharyngeal (n=21, 36.9%) and oculoglandular (n=8, 14%). In all patients enlargement of the lymph nodes was reported, most frequently the cervical ones (n=52, 91.2%). Ultrasound imaging showed hepatosplenomegaly in three cases (5.2%). Antibiotics were given prior to admission for 26 (45.6%) patients and during hospitalization for 54 (94.8%). Twenty-three (40.4%) received monotherapy while 31 (54.4%) received combined therapy. Diagnosis was based on agglutination reaction in most cases (n=50, 87.7%). For seven patients, diagnosis was made based on only clinical-epidemiological history without laboratory confirmation (n=7, 12.3%). Surgical treatment was used for 8.8% patients. Presence of rodents at household was mentioned by 14 (24.6%), while four (7%) noted a vector bite and three (5.3%) had contact with rodents. Over half (56.2%) had centralized water. Conclusion: Most of the patients were male and from rural areas. People from 19-30 years of age were more likely to contract tularemia. Approximately half of the patients had the bubonic form, mainly cervical. Other potential risk factors that might explain a long hospitalization (e.g. suppressed immune system, treatment failure etc.), should be a topic for future investigations.

The conditions for the formation of nanocomposites based on the basis of lattice packings of SiO2 nanospheres (opal matrices) with included crystallites of lead titanates (PbTiO3 and PbTi3O7) in interspherical nanospacing are considered. For the formation of nanocomposites are used sample opal matrices with dimensions of single-domain regions ≥0,1 mm.3 The diameter of SiO2 nanospheres was ∼260 nm. Obtained nanocomposites volume >2 cm3 in filling >20% of interspherical nanospacing PbTiO3, PbTi3O7 crystallites were size of 16-36 nm. Using X-ray diffraction and Raman spectroscopy are studied composition and structural stability when heated nanocomposites to 550°C, which allowed the identification of a local phase transition with change of the space group. The dependence of the composition of synthesized materials on the conditions of their preparation is submitted.