Boundary Between Stable and Unstable Regimes of Accretion

We investigated the boundary between stable and unstable regimes of accretion and its dependence on different parameters. Simulations were performed using a "cubed sphere" code with high grid resolution (244 grid points in the azimuthal direction), which is twice as high as that used in our earlier studies. We chose a very low viscosity value, with alpha-parameter alpha=0.02. We observed from the simulations that the boundary strongly depends on the ratio between magnetospheric radius r_m (where the magnetic stress in the magnetosphere matches the matter stress in the disk) and corotation radius r_cor (where the Keplerian velocity in the disk is equal to the angular velocity of the star). For a small misalignment angle of the dipole field, Theta=5 degrees, accretion is unstable if r_cor/r_m>1.35, and is stable otherwise. In cases of a larger misalignment angle of the dipole, Theta=20 degrees, instability occurs at slightly larger values, r_cor/r_m>1.41.Comment: 4 pages, 4 figures, conference proceedings: "Physics at the Magnetospheric Boundary", Geneva, Switzerland, 25-28 June, 201

Experiments with Monopoles, Rings and Knots in Spinor Bose-Einstein Condensates

Topological excitations are ubiquitous in nature, their charge being a naturally-quantized, conserved quantity that can exhibit particle-like behavior. Spinor Bose-Einstein condensates (BECs) are an exceptionally versatile system for the study and exploration of topological excitations. Between the spin-1 and spin-2 87Rb condensates there are seven possible broken-symmetry magnetic phases, with each one hosting unique opportunities for topological defects. We have created and observed several novel topological excitations in a spinor 87Rb BEC. In this dissertation I present and discuss three principal experimental findings: (1) The discovery of an Alice ring, or a half-quantum vortex ring, emerging from a monopole singularity in a nematic spin-1 BEC; (2) The first realization of a \u27t Hooft-Polyakov-type monopole in a nematic spin-2 BEC; and (3) The first realization of a knot in a nematic spin-2 BEC. This dissertation concludes with possible avenues for future research

Euphemisms of the Concept of death in the Internet Discourse of the Modern Russian Language (on the Material of Nominations of Death-groups)

Статья посвящена эвфемизмам с семантикой смерти, которые используются участниками так называемых «групп смерти» в интернет-дискурсе. Приводятся определения понятий «концепт» и «эвфемизм». Рассматривается несколько групп образов, через которые в названиях маскируется тема смерти и самоубийства. Автор считает, что посредством эвфемизации достигается эффект устранения негативных смыслов, подменяемых привлекательным образом. Использование метафорических номинаций характеризуется как основной и самый частотный способ эвфемизации.The article is devoted to euphemisms with the semantics of death, which are used in the nominations of death groups in the Internet. The definitions of concepts “concept” and “euphemism” are given. Several groups of images are considered and highlighted, through which the nominations mask the theme of death and suicide. Thus the nominations do not carry unpleasant information about death and distract the participants from recognizing it. The way of using metaphorical nominations is singled out as the main and most frequent way of evfemization

Constraints on the cooling history of the H-chondrite parent body from phosphate and chondrule Pb-isotopic dates from Estacado

To constrain the metamorphic history of the H-chondrite parent body, we dated phosphates and chondrules from four H6 chondritic meteorites using U-Pb systematics. Reconnaissance analyses revealed that only Estacado had a sufficiently high 206Pb/204Pb ratio suitable for our purposes. The Pb-Pb isochron date for Estacado phosphates is measured to be 4492 ± 15 Ma. The internal residue-second leachate isochron for Estacado chondrules yielded the chondrule date of 4546 ± 18 Ma. An alternative age estimate for Estacado chondrules of 4527.6 ± 6.3 Ma is obtained from an isochron including two chondrules, two magnetically separated fractions, and four bulk chondrite analyses. This isochron date might represent the age of termination of Pb diffusion from the chondrules to the matrix. From these dates and previously established closure temperatures for Pb diffusion in phosphates and chondrules, we estimate an average cooling rate for Estacado between 5.5 ± 3.2 Myr/°C and 8.3 ± 5.0 Myr/°C. Using previously published results for Ste. Marguerite (H4) and Richardton (H5), our data reveal that the cooling rates of H chondrites decrease markedly with increasing metamorphic grade, in agreement with the predictions of the "onion-shell" asteroid model. Several issues, however, need to be addressed before confirming this model for the H-chondrite parent body: the discrepancies between peak metamorphic temperatures established by various mineral thermometers need to be resolved, diffusion and other mechanisms of element migration in polycrystalline solids must be better understood, and dating techniques should be further improved

Experimental realization of a Dirac monopole through the decay of an isolated monopole

We experimentally observe the decay dynamics of deterministically created isolated monopoles in spin-1 Bose-Einstein condensates. As the condensate undergoes a change between magnetic phases, the isolated monopole gradually evolves into a spin configuration hosting a Dirac monopole in its synthetic magnetic field. We characterize in detail the Dirac monopole by measuring the particle densities of the spin states projected along different quantization axes. Importantly, we observe the spontaneous emergence of nodal lines in the condensate density that accompany the Dirac monopole. We also demonstrate that the monopole decay accelerates in weaker magnetic field gradients.Comment: 10 pages, 7 figure

Multimodality in Online Political Discourse: Internet Memes about Scottish Independence

The article is dedicated to the mediation of the possible independence of Scotland in social networks. A multimodal analysis of thematic Internet memes 2014-2016 is carried out as examples of online political discourse. Online political discourse is characterized as an object of linguistic and multimodal analysis. This type of discourse is considered as an uninstitutional kind of political discourse in general, characterized by informality, spontaneity, high speed of response to public challenges and polyphony. The ability of network political discourse to compress information and the estimated interpretation of reflected reality is noted. The concept of inter-discursiveness is considered as one of the genre-forming features of network political discourse in general and Internet memes in particular. The definition of multimodal text as involving the verbal and visual channels of perception, both of which contain key elements of information for decoding the meaning, is given. Various definitions of the Internet meme as a multimodal genre of Internet communication are considered. The analysis of four Internet memes about the independence of Scotland is given. Memes are analyzed for the relationship of verbal and visual component; stylistic characteristics of the text component; strong and weak position of the visual component; sources of precedent and interdiscursive nature of relations between components