Effect of Permittivity on the Electric-Field-Driven Rotation Dynamics in a Liquid Film

Applying a constant electric field on a suspended film of liquid that carries an electric current, either by the transport of ions or surface charges, induces a rotation in the film. This system is known as “liquid film motor”. So far, the effect of permittivity of the liquid on its rotation has been ignored. We showed that the permittivity of the liquid can significantly affect the dynamics of rotation. Using an experimental approach, we studied the liquid film rotation for a broad range of pure liquids with diverse permittivities and surface tensions. We observed two different regimes of rotation depending on the permittivity of the liquids. We also found that there is no correlation between the surface tension of the liquid and the angular velocity of the rotation. We considered a theoretical framework and suggested scenarios to explain our experimental observations. These results help in better understanding the physics of liquid film motors and suggest opportunities for new flow manipulation techniques at small scales.

MONASTERIES OF THE TVER HALF OF THE BEZHETSKAYA PYATINA AT THE END OF THE 15TH - 16TH CENTURIES: LOCALIZATION, LAND OWNERSHIP

Статья посвящена монастырям и монастырскому землевладению в Тверской половине Бежецкой пятины в конце XV - XVI в. Основными источниками являются писцовые книги, привлекается актовый материал, описания XIX - начала ХХ в. В общей сложности выявлена информация о десяти монастырях, девять из которых возникло в XVI в. Наиболее ранним, предположительно, является Иоанно-Богословский монастырь в волости Удомля. Размеры монастырей Тверской половины Бежецкой пятины были невелики, землевладения располагались в непосредственной близости от самих монастырей. Более крупными являлись владения новгородских обителей - Воскресенского на Мячине, Кириллова, Юрьева, Троицкого Млёвского. В целом монастырское землевладение в Тверской половине Бежецкой пятины после присоединения Новгорода к Московскому государству уступало размерам владений Хутынского и Аркажского монастырей на этой территории в период новгородской самостоятельности. Небольшие размеры монастырского землевладения и малое количество монастырей на изучаемой территории объясняется ее периферийностью по отношению к Новгороду. Возникшие в XVI в. монастыри находились на сухопутных и водных путях сообщения. Упадок монастырского хозяйства наблюдается с последней четверти XVI в. Формирование систем приписных монастырей в XVII в., вероятно, являлось попыткой выхода из кризиса путем консолидации монастырских ресурсов. The article is devoted to the monasteries and monastery land ownership in the Tver half of the Bezhetskaya pyatina at the end of the 15th - 16th centuries. The main sources are the scribe books, acts, descriptions of the 19th - early 20th centuries. In total, information was revealed about ten monasteries, nine of which arose in the 16th centuries. The earliest, presumably, is the John Theological Monastery in the Udomlya volost. The size of the monasteries of the Tver half of the Bezhetskaya pyatina was very small, the land ownership was usually located in the immediate vicinity of the monasteries themselves. The larger ones were the lands of the Novgorod monasteries - the monastery of the Resurrection on Myachino, Kirillov, Yuryev, as well as the monastery of the St. Trinity Mlevsky.In general, the monastery land ownership in the Tver half of the Bezhetskaya pyatina after the accession of the Novgorod to the Moscow state was very small and inferior to the size of the lands of the Khutynsky and Arkazhsky monasteries in this territory during the period of Novgorod independence. Small scales of monastery land ownership and a small number of monasteries in the area under the research are explained by its periphery in relation to Novgorod. At the same time, the monasteries that arose in the 16th century were on land roads and waterways. The decline of the monastery economy has been observed since the last quarter of the 16th century. The formation of systems of ascribed monasteries in the 17th century was probably an attempt to overcome the crisis by the consolidation of the monastery resources.

Refugees and the Mission of the Church

The world has changed and shifted. Regional demographics on both large and small scales look drastically different and are constantly changing from just one lifetime ago, as the World Christian Encyclopedia, third edition, has shown us. Forced migration is an integral part of the shifting landscape. One might wonder what God is doing in the midst of this. This article focuses on forced migration and the response of the church to the global refugee crisis.

Synchronization of low Reynolds number plane Couette turbulence

We demonstrate that in plane Couette turbulence a separation of the velocity field in large and small scales according to a streamwise Fourier decomposition allows us to identify an active subspace comprising a small number of the gravest streamwise components of the flow that can synchronize all the remaining streamwise flow components. The critical streamwise wavelength, $\ell _{x c}$ , that separates the active from the synchronized passive subspace is identified as the streamwise wavelength at which perturbations to the time-dependent turbulent flow with streamwise wavelengths $\ell _x<\ell _{xc}$ have negative characteristic Lyapunov exponents. The critical wavelength is found to be approximately 130 wall units and obeys viscous scaling at these Reynolds numbers.

Spatial Variation in Temperature and Density in the IC 63 PDR from H2 Spectroscopy

We have measured the gas temperature in the IC 63 photodissociation region (PDR) using the S(1) and S(5) pure rotation lines of molecular hydrogen with SOFIA/EXES. We divide the PDR into three regions for analysis based on the illumination from γ Cas: sunny, ridge, and shady. Constructing rotation diagrams for the different regions, we obtain temperatures of T ex = 562 − 43 + 52 K toward the ridge and T ex = 495 − 25 + 28 K in the shady side. The H2 emission was not detected on the sunny side of the ridge, likely due to the photodissociation of H2 in this gas. Our temperature values are lower than the value of T ex = 685 ± 68 K using the S(1), S(3), and S(5) pure rotation lines, derived by Thi et al. using lower spatial resolution ISO-SWS data at a different location of the IC 63 PDR. This difference indicates that the PDR is inhomogeneous and illustrates the need for high-resolution mapping of such regions to fully understand their physics. The detection of a temperature gradient correlated with the extinction into the cloud, points to the ability of using H2 pure rotational line spectroscopy to map the gas temperature on small scales. We used a PDR model to estimate the FUV radiation and corresponding gas densities in IC 63. Our results shows the capability of SOFIA/EXES to resolve and provide detailed information on the temperature in such regions.

Fluid Energy Cascade Rate and Kinetic Damping: New Insight from 3D Landau-fluid Simulations

Using an exact law for incompressible Hall magnetohydrodynamics (HMHD) turbulence, the energy cascade rate is computed from three-dimensional HMHD-CGL (biadiabatic ions and isothermal electrons) and Landau-fluid numerical simulations that feature different intensities of Landau damping over a broad range of wavenumbers, typically 0.05 ≲ k ⊥ d i ≲ 100. Using three sets of cross-scale simulations where turbulence is initiated at large, medium, and small scales, the ability of the fluid energy cascade to “sense” the kinetic Landau damping at different scales is tested. The cascade rate estimated from the exact law and the dissipation calculated directly from the simulation are shown to reflect the role of Landau damping in dissipating energy at all scales, with an emphasis on the kinetic ones. This result provides new prospects on using exact laws for simplified fluid models to analyze dissipation in kinetic simulations and spacecraft observations, and new insights into theoretical description of collisionless magnetized plasmas.

Analytical warm dark matter power spectrum on small scales

Using the Reduced Relativistic Gas (RRG) model, we analytically determine the matter power spectrum for Warm Dark Matter (WDM) on small scales, k > 1 h/Mpc. The RRG is a simplified model for the ideal relativistic gas, but very accurate in the cosmological context. In another work, we have shown that, for typical allowed masses for dark matter particles, m>5 keV, the higher order multipoles, ℓ ≥ 2, in the Einstein-Boltzmann system of equations are negligible on scales k < 10 h/Mpc. Hence, we can follow the perturbations of WDM using the ideal fluid framework, with equation of state and sound speed of perturbations given by the RRG model. We derive a Mészáros-like equation for WDM and solve it analytically in radiation, matter and dark energy dominated eras. Joining these solutions, we get an expression that determines the value of WDM perturbations as a function of redshift and wavenumber. Then we construct the matter power spectrum and transfer function of WDM on small scales and compare it to some results coming from Lyman-α forest observations. Besides being a clear and pedagogical analytical development to understand the evolution of WDM perturbations, our power spectrum results are consistent with the observations considered and the other determinations of the degree of warmness of dark matter particles.

Drift Estimation of Multiscale Diffusions Based on Filtered Data

We study the problem of drift estimation for two-scale continuous time series. We set ourselves in the framework of overdamped Langevin equations, for which a single-scale surrogate homogenized equation exists. In this setting, estimating the drift coefficient of the homogenized equation requires pre-processing of the data, often in the form of subsampling; this is because the two-scale equation and the homogenized single-scale equation are incompatible at small scales, generating mutually singular measures on the path space. We avoid subsampling and work instead with filtered data, found by application of an appropriate kernel function, and compute maximum likelihood estimators based on the filtered process. We show that the estimators we propose are asymptotically unbiased and demonstrate numerically the advantages of our method with respect to subsampling. Finally, we show how our filtered data methodology can be combined with Bayesian techniques and provide a full uncertainty quantification of the inference procedure.