Magnetization dynamics in patterned thin films

Wydział Fizyki.Głównym celem rozprawy jest badanie oddziaływania drgań magnetostatycznych z elementami strukturyzowanymi permaloju (Py) i granatu itro żelazowego (YIG). Badania eksperymentalne wykonano metodą spektroskopii rozpraszania światła Brillouina. Zbadano zjawisko nieliniowego zwielokrotniania częstotliwości przy dużych mocach wzbudzania w eliptycznych kropkach Py o rozmiarach submikrometrowych. Zaobserwowano, że charakterystyki rezonansowej odpowiedzi zależą od przestrzennej symetrii modu dynamicznego i są różne w przypadku drugiej i trzeciej harmonicznej. Wykazano, że rozpraszanie fali spinowej na pojedynczej antykropce stanowi pasywną metodę wytwarzania kaustycznej fali spinowej w YIG. Wykazano dobrą zgodność wyników doświadczalnych z przewidywaniami teoretycznymi opartymi o teorię fal spinowych dla cienkich warstw. Zaproponowano i doświadczalnie wykazano, że linia antykropek może stanowić zwierciadło magnetyczne powodujące całkowite wewnętrzne odbicie fal spinowych i że fala ta o dużej intensywności propaguje się wzdłuż linii antykropek przy pewnym kącie krytycznym Θcrit, mierzonym pomiędzy linią antykropek i kierunkiem pola magnetycznego. Potwierdzono wyniki eksperymentalne poprzez symulacje mikromagnetyczne wykonane z wykorzystaniem programu OOMMF i wykazano, że krzywe stałej częstotliwości stanowią bardzo użyteczne narzędzie przy interpretacji wyników eksperymentalnych.The main aim of this dissertation is study the interaction of magnetostatic oscillation with patterned permalloy (Py) and yttrium iron garnet (YIG) films. As a method for studying, the Brillouin light scattering spectroscopy has been selected. The most important achievement, are the following: The examination of the phenomenon of nonlinear frequency multiplication in submicrometer sized Pyelliptical dots at large excitation power. The observation that the resonant enhancement are dependent on the spatial symmetry of the dynamical mode and are different for the double and the tripleharmonics. The observation of spin waves scattering from the singleantidot as a passive way to the creation of the caustic beams in YIG films. The application of the magnetostatic spin wave theory for thin films and demonstration of a good agreement between the experimental and tehoretical data.The proposition and experimental demonstration of the total nonreflection of spin waves by an antidots array. Showing that a highly intense beam of spin waves propagates along these antidots at the critical angle Θcrit, which was measured between the line of antidots and the direction of megnetic field. Showing that the results of the OOMMF simulations are consistent with the experimental results and the isofrequency dependences provide a good tool for the clear interpretation of the experimental data

Probability theory and public-key cryptography

In this short note, we address a common misconception at the interface of probability theory and public-key cryptography.Comment: 5 page

Исследование причин разброса данных о распространённости мышечно-суставной дисфункции височно-нижнечелюстных суставов у стоматологических больных

Aim of research. To study biopotentials of chewing muscles and possible noise phenomena in temporomandibular joints in dental patients, who have two and more symptoms of a muscle and joint dysfunction of a temporomandibular joint with no complaints for pains in chewing muscles at movements of a lower jaw as ones of criteria for substantiating appropriateness of setting the diagnosis of a temporomandibular joint dysfunction.Materials and methods. The group of 136 persons with 2,3,4 and more symptoms of a temporomandibular joint dysfunction, deviations in the work of the joint, but no complaints for pains at movements of a law jaw and chewing was formed of patients of the dental clinic. Results of research. The artrophonographic study demonstrated that patients with 2 and 3 symptoms related to a muscle and joint dysfunction of a temporomandibular joint, demonstrate disorders in the work of a temporomandibular joint (56,6% of patients) and ones with 4 and more symptoms – in 64,1%. The electromiographic study revealed the absence of disorders of biopotentials of chewing muscles in all 136 patients.Conclusions. One can make a conclusion that a muscle and joint dysfunction of a temporomandibular joint must not be diagnosed in these patients. The repeated examination, realized in 6 months proved the absence of worsening of a condition of chewing muscles and temporomandibular joint in such patients. Assessments of the prevalence of this disease, presented in literary sources, are overestimated unreasonably in a series of casesНа базе проведенных исследований обосновано положение о том, что основой постановки диагноза мышечно-суставной дисфункции височно-нижнечелюстного сустава должно быть не только наличие симптомов, относимых к этому заболеванию, а установленные с помощью электромиографии нарушения биопотенциалов жевательных мышц . Диагностика данного заболевания, не учитывающая этого положения, необоснованно завышает показатели распространенности мышечно-суставной дисфункции височно-нижнечелюстного сустав

Resonance Compression of Acoustic Beams in Crystals

The resonant excitation of an intense elastic wave through nonspecular reflection of a special pump wave in a crystal is described. Geometric criteria are found under which mode conversion, when the incident and reflected beams belong to different acoustic branches, coexists with total internal reflection of an acoustic beam. In this case, the entire energy of an incident pump wave is spent on the excitation of a narrow intense reflected beam close in structure to an eigenmode. A consistent choice of orientations of the sagittal plane and crystal surface that excludes the reflection of a parasitic wave of leakage is found. The resonance parameters have been found for a medium with an arbitrary anisotropy. General relations are concretized for monoclinic, orthorhombic, trigonal, tetragonal, cubic, and hexagonal systems. Estimates and illustrations are given for a series of such crystals. The intensity of the reflected beam increases with its narrowing, but its diffraction divergence also increases with this narrowing. Nevertheless, the intensity of the beam can be increased by a factor of 5–10 at sufficiently high frequencies while keeping its divergence at an acceptable level. Amplification by two orders of magnitude can be achieved by compressing the beam in two dimensions through its double reflection

Chiral charge pumping in graphene deposited on a magnetic insulator

We demonstrate that a sizable chiral charge pumping can be achieved at room temperature in graphene/Yttrium Iron Garnet (YIG) bilayer systems. The effect, which cannot be attributed to the ordinary spin pumping, reveals itself in the creation of a dc electric field/voltage in graphene as a response to the dynamic magnetic excitations (spin waves) in an adjacent out-of-plane magnetized YIG film. We show that the induced voltage changes its sign when the orientation of the static magnetization is reversed, clearly indicating the broken spatial inversion symmetry in the studied system. The strength of effect shows a non-monotonous dependence on the spin-wave frequency, in agreement with the proposed theoretical model.Comment: 8 pages, 5 figure

Ethno-pharmacological review on the wild edible medicinal plant, Lilium martagon L

Purpose: Martagon lily (Lilium martagon L.) is used in Eastern traditional medicine for wound healing and treatment of toothache. This review is intended to provide a comprehensive and critical evaluation of the chemical, botanical, ethnological, pharmacological, and pharmacognostic aspects of L. martagon, with a view to facilitating further in-depth pharmaceutical studies on the potentials of the plant as a herbal remedy. Methods: Diverse electronic search engines and specialized reference tools such as Google, Google Scholar, Scopus, Web of Science, scientific literature, publishing sites and electronic databases (Pubmed, Springer, Wiley and Science Direct) were used for data retrieval. The data focused on botany, traditional uses, biological activities and phytochemistry of L. martagon, with emphasis on integration of this plant in official medicare. Results: Lilium martagon possesses anti-inflammatory, sedative, anticancer, analgesic and hemostatic properties. Some modern techniques (in vitro propagation, genetic manipulation and advanced molecular biology techniques) have been applied in L. martagon biotechnology, with respect to major plant diseases and genetic variation issues. Conclusion: Lilium martagon L contains different groups of biologically-active substances, amongst which are pyrroline derivatives and steroidal saponins. These may justify the usage of this plant and its subspecies in the traditional treatment of a wide spectrum of diseases

Emergence and competition of virus variants in respiratory viral infections

The emergence of new variants of concern (VOCs) of the SARS-CoV-2 infection is one of the main factors of epidemic progression. Their development can be characterized by three critical stages: virus mutation leading to the appearance of new viable variants; the competition of different variants leading to the production of a sufficiently large number of copies; and infection transmission between individuals and its spreading in the population. The first two stages take place at the individual level (infected individual), while the third one takes place at the population level with possible competition between different variants. This work is devoted to the mathematical modeling of the first two stages of this process: the emergence of new variants and their progression in the epithelial tissue with a possible competition between them. The emergence of new virus variants is modeled with non-local reaction–diffusion equations describing virus evolution and immune escape in the space of genotypes. The conditions of the emergence of new virus variants are determined by the mutation rate, the cross-reactivity of the immune response, and the rates of virus replication and death. Once different variants emerge, they spread in the infected tissue with a certain speed and viral load that can be determined through the parameters of the model. The competition of different variants for uninfected cells leads to the emergence of a single dominant variant and the elimination of the others due to competitive exclusion. The dominant variant is the one with the maximal individual spreading speed. Thus, the emergence of new variants at the individual level is determined by the immune escape and by the virus spreading speed in the infected tissue

Symbols of truncated Toeplitz operators

We consider three problems connected with coinvariant subspaces of the backward shift operator in Hardy spaces $H^p$: 1) properties of truncated Toeplitz operators; 2) Carleson-type embedding theorems for the coinvariant subspaces; 3) factorizations of pseudocontinuable functions from $H^1$. These problems turn out to be closely connected and even, in a sense, equivalent. The new approach based on the factorizations allows us to answer a number of challenging questions about truncated Toeplitz operators posed by Donald Sarason.Comment: 19 page