The generation and autoresonant excitation of a magnetic breather in a three-layer ferromagnet by fields of variable frequency and small amplitude in the presence of dissipation in the system is considered. The ferromagnetic structure consists of two wide identical layers separated by a thin layer with modified values of the magnetic anisotropy parameter. The anisotropy parameters are considered functions of the coordinate directed perpendicular to the layer interface. In the one-dimensional case, the function of the anisotropy parameter is modeled in the form of a rectangle. The external magnetic field is variable in time with a small amplitude and frequency, which is a linear function of time. The obtained equation of motion for magnetization in the form of a sine-Gordon equation was solved numerically using an explicit integration scheme. The distribution of magnetization at the initial time was set in the form of a Bloch domain boundary, located far from a thin layer. At certain values of the parameters of a thin layer, when a domain wall passes at a constant speed through it, a magnetic inhomogeneity is formed in the form of a magnetic breather. In the absence of an external field, the breather amplitude decays with time. An analysis of the solutions of the equation of motion in an alternating field shows the possibility, under certain conditions, of increasing with time the amplitude of the magnetic breather. For each case of magnetic anisotropy parameter values, there is a threshold value of the magnetic field amplitude leading to resonance. The resonance effect is also affected by the geometric parameters of a thin layer: with a decrease in the width of the layer, the amplitude of the breather increases more slowly in time. With a large layer width, the translational mode of breather oscillations is also excited.
Generation and excitation of a magnetic soliton in a three-layer ferromagnet using dc magnetic fields and weak ac fields in the presence of dissipation in the system have been considered. An analysis of the solutions to the equation of motion in an ac field shows the possibility of increasing the magnetic-soliton amplitude with time under certain conditions. The resonance effect is also affected by the geometric parameters of the thin layer: the translational mode of soliton oscillations is excited at a large layer width.
Possibility of changing the dynamic parameters of localized breather and soliton waves for the sine-Gordon equation in the model with extended impurity, variable external force and dissipation was investigated using the autoresonance method. The model of ferromagnetic structure consisting of two wide identical layers separated by a thin layer with modified values of magnetic anisotropy parameter was taken as a basis. Frequency of external field is a linear function of time. The sine-Gordon equation (SGE) was solved numerically using the finite differences method with explicit scheme of integration. For certain values of the extended impurity parameters a magnetic inhomogeneity in the form of magnetic breather is formed when domain wall passes through it with constant velocity. The numerical simulation showed that using special variable force and small amplitude it is possible to resonantly increase the amplitude of breather. For each case of the impurity parameters values, there is a threshold value of the magnetic field amplitude leading to resonance. Geometric parameters of thin layer also have influence on the resonance effect — for decreasing layer width the breather amplitude grows more slowly. For large layer width the translation mode of breather oscillations is also excited. For certain parameters of extended impurity, a soliton can form. For a special type of variable field with frequency linearly dependent on time, soliton is switched to antisoliton and vice versa.
In order to assess the clinical eff ectiveness of COVID-19 complex therapy in adults, 140 patients with a confi rmed diagnosis of a new coronavirus infection, clinical symptoms and lung damage from 25 to 75 % (mild and moderate form) hospitalized in budgetary healthcare institutions of the Omsk region were included in an open prospective observational study. Patients were evenly divided into two groups: 1 — received standard therapy in accordance with the Temporary Guidelines "Prevention, diagnosis and treatment of new coronavirus infection (COVID-19)" approved by the Ministry of Health of the Russian Federation and interferon alpha-2b preparations (Viferon ® rectal suppositories 3,000,000 IU and Viferon ® gel for external and topical use of 36,000 IU/g); 2 — received only standard therapy. In group 1 patients, elimination of the SARS-CoV-2 antigen from the nasopharyngeal mucosa occurred 2 days earlier than in group 2 patients. Also, patients receiving standard therapy and interferon alpha-2b preparations improved on average 4.5 days earlier, most of the main symptoms of the disease were stopped by the 6th day of therapy. It was noted that in patients receiving complex standard therapy with adding of interferon alpha-2b preparations, a more pronounced regression of lung tissue damage was observed, especially in patients with a high degree of their lesion according to CT data before hospitalization. By the end of treatment in group 1, the proportion of patients with lung tissue lesions of grade CT-3 signifi cantly decreased by 17%, while in group 2, the proportion of patients with CT-3 increased by 13 %. Analysis of the dynamics of laboratory parameters and the main markers of infl ammation in the therapy groups also confi rms the positive eff ect of the inclusion of interferon alpha-2b drugs in the standard therapy. No adverse events associated with the use of interferon alpha-2b preparations were registered. Thus, in patients receiving standard therapy and interferon alpha-2b preparations, recovery occurred in a shorter time. In the end, this contributed to a faster discharge from the hospital and a reduction in the burden on the bed fund and medical staff . The results obtained give grounds to recommend the inclusion of interferon alpha-2b preparations (Viferon ® rectal suppositories 3,000,000 IU and Viferon ® gel for external and topical use 36,000 IU/g) in standard COVID-19 therapy regimens in adult patients with mild and moderate forms of the disease.
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