Channeling 5-min photospheric oscillations into the solar outer atmosphere through small-scale vertical magnetic flux tubes

We report two-dimensional MHD simulations which demonstrate that photospheric 5-min oscillations can leak into the chromosphere inside small-scale vertical magnetic flux tubes. The results of our numerical experiments are compatible with those inferred from simultaneous spectropolarimetric observations of the photosphere and chromosphere obtained with the Tenerife Infrared Polarimeter (TIP) at 10830 A. We conclude that the efficiency of energy exchange by radiation in the solar photosphere can lead to a significant reduction of the cut-off frequency and may allow for the propagation of the 5 minutes waves vertically into the chromosphere.Comment: accepted by ApJ

Spreading of a saturation front of heterogeneous chemical reaction througn an aerosol gloud

A cloud of aerosol particles sediments in air containing reactants. On the basis of a macroscopic chemical and mass transfer model founded on the kinetic theory of heterogeneous reactions we analyzed the spreading of chemical reaction through the cloud of aerosol particlesyesBelgorod State National Research Universit

Acoustic-gravity wave propagation characteristics in 3D radiation hydrodynamic simulations of the solar atmosphere

There has been tremendous progress in the degree of realism of three-dimensional radiation magneto-hydrodynamic simulations of the solar atmosphere in the past decades. Four of the most frequently used numerical codes are Bifrost, CO5BOLD, MANCHA3D, and MURaM. Here we test and compare the wave propagation characteristics in model runs from these four codes by measuring the dispersion relation of acoustic-gravity waves at various heights. We find considerable differences between the various models. The height dependence of wave power, in particular of high-frequency waves, varies by up to two orders of magnitude between the models, and the phase difference spectra of several models show unexpected features, including $\pm180^\circ$ phase jumps.Comment: 19 pages, 15 figure

Properties of high-frequency wave power halos around active regions: an analysis of multi-height data from HMI and AIA onboard SDO

We study properties of waves of frequencies above the photospheric acoustic cut-off of $\approx$5.3 mHz, around four active regions, through spatial maps of their power estimated using data from Helioseismic and Magnetic Imager (HMI) and Atmospheric Imaging Assembly (AIA) onboard Solar Dynamics Observatory (SDO). The wavelength channels 1600 {\AA} and 1700 {\AA} from AIA are now known to capture clear oscillation signals due to helioseismic p modes as well as waves propagating up through to the chromosphere. Here we study in detail, in comparison with HMI Doppler data, properties of the power maps, especially the so called 'acoustic halos' seen around active regions, as a function of wave frequencies, inclination and strength of magnetic field (derived from the vector field observations by HMI) and observation height. We infer possible signatures of (magneto-)acoustic wave refraction from the observation height dependent changes, and hence due to changing magnetic strength and geometry, in the dependences of power maps on the photospheric magnetic quantities. We discuss the implications for theories of p mode absorption and mode conversions by the magnetic field.Comment: 22 pages, 12 figures, Accepted by journal Solar Physic

A breach in plant defences: Pseudomonas syringae pv. actinidiae targets ethylene signalling to overcome Actinidia chinensis pathogen responses

Ethylene interacts with other plant hormones to modulate many aspects of plant metabolism, including defence and stomata regulation. Therefore, its manipulation may allow plant pathogens to overcome the host’s immune responses. This work investigates the role of ethylene as a virulence factor for Pseudomonas syringae pv. actinidiae (Psa), the aetiological agent of the bacterial canker of kiwifruit. The pandemic, highly virulent biovar of this pathogen produces ethylene, whereas the biovars isolated in Japan and Korea do not. Ethylene production is modulated in planta by light/dark cycle. Exogenous ethylene application stimulates bacterial virulence, and restricts or increases host colonisation if performed before or after inoculation, respectively. The deletion of a gene, unrelated to known bacterial biosynthetic pathways and putatively encoding for an oxidoreductase, abolishes ethylene production and reduces the pathogen growth rate in planta. Ethylene production by Psa may be a recently and independently evolved virulence trait in the arms race against the host. Plantand pathogen-derived ethylene may concur in the activation/suppression of immune responses, in the chemotaxis toward a suitable entry point, or in the endophytic colonisation

Effects of transport and phase equilibrium on fast, nearly irreversible reactive extraction

Abstract Integration of reaction and separation can be exploited to drive reversible reactions in the direction of the desired product using multiphase flow contacting. In the case of nearly irreversible, fast reactions, however, the dynamics of the product have little influence on the reactor efficiency in say liquid-liquid reactive extraction. A similar intensification in reaction efficiency to reactive separation can be achieved by exploiting phase equilibrium or asymmetry in mass transfer rates of the reactants. Here, a model for two-layer biphasic flow and homogeneous reaction is proposed for co-current reactive extraction, demonstrating that localization and intensification of reaction occurs in the region between the entrance and crossover. Crossover occurs if the reactant in stoichiometric deficit preferentially populates the reacting phase due to sufficient imbalance in either mass transfer coefficients or phase equilibrium. We develop an infinite Peclet number (convection dominates over bulk diffusion) model that indicates that crossover occurs when for fast, irreversible reactions. u 0 and v 0 are initial charges to the tubular reactor, the 's are mass transfer coefficients for each side of the fluid interface and the h's are Henry's Law coefficients for reactants U and V . The interpretation of this formula is that if v 0 > u 0 , then crossover will occur if the overall mass transfer rate of U is faster than the overall mass transfer rate for V . Downstream of the crossover point, the reactant in stoichiometric excess also dominates the reacting phase due to relative exhaustion of the more-mobile component. A finite Peclet number theory for fast, irreversible reaction shows that the above formula is a conservative limit for crossover-if it holds, crossover will occur regardless of the Peclet number. A formula for the larger parametric region for crossover with finite Peclet number is derived. Verification that crossover is achieved is found by finite-element numerical analysis of the full governing equations. Both theory and numerical analysis predict localization and intensification of the reaction due to crossover. Crossover sets the length scale as approximately two and a half crossover lengths for completed reaction for sufficiently high Peclet number with strong kinetic asymmetry. The theory predicts that taking the ratio of inlet concentrations S = u 0 /v 0 to be the critical value at fixed physical parameters for mass transfer and phase equilibrium maximizes localization and reactor efficiency. Similarly, the kinetic asymmetry should be as large as possible to exploit the benefits of crossover.

Spatial and sector-specific contributions of emissions to ambient air pollution and mortality in European cities: a health impact assessment

Background Ambient air pollution is a major risk to health and wellbeing in European cities. We aimed to estimate spatial and sector-specific contributions of emissions to ambient air pollution and evaluate the effects of source-specific reductions in pollutants on mortality in European cities to support targeted source-specific actions to address air pollution and promote population health. Methods We conducted a health impact assessment of data from 2015 for 857 European cities to estimate source contributions to annual PM2·5 and NO2 concentrations using the Screening for High Emission Reduction Potentials for Air quality tool. We evaluated contributions from transport, industry, energy, residential, agriculture, shipping, and aviation, other, natural, and external sources. For each city and sector, three spatial levels were considered: contributions from the same city, the rest of the country, and transboundary. Mortality effects were estimated for adult populations (ie, ≥20 years) following standard comparative risk assessment methods to calculate the annual mortality preventable on spatial and sector-specific reductions in PM2·5 and NO2. Findings We observed strong variability in spatial and sectoral contributions among European cities. For PM2·5, the main contributors to mortality were the residential (mean contribution of 22·7% [SD 10·2]) and agricultural (18·0% [7·7]) sectors, followed by industry (13·8% [6·0]), transport (13·5% [5·8]), energy (10·0% [6·4]), and shipping (5·5% [5·7]). For NO2, the main contributor to mortality was transport (48·5% [SD 15·2]), with additional contributions from industry (15·0% [10·8]), energy (14·7% [12·9]), residential (10·3% [5·0]), and shipping (9·7% [12·7]). The mean city contribution to its own air pollution mortality was 13·5% (SD 9·9) for PM2·5 and 34·4% (19·6) for NO2, and contribution increased among cities of largest area (22·3% [12·2] for PM2·5 and 52·2% [19·4] for NO2) and among European capitals (29·9% [12·5] for PM2·5 and 62·7% [14·7] for NO2). Interpretation We estimated source-specific air pollution health effects at the city level. Our results show strong variability, emphasising the need for local policies and coordinated actions that consider city-level specificities in source contributions. Funding Spanish Ministry of Science and Innovation, State Research Agency, Generalitat de Catalunya, Centro de Investigación Biomédica en red Epidemiología y Salud Pública, and Urban Burden of Disease Estimation for Policy Making 2023-2026 Horizon Europe project

Stochastic theory of ultrathin lubricant film melting in stick-slip regime

Melting of an ultrafhin lubricant film under friction between atomically smooth surfaces is studied in terms of the Lorentz model. Additive noise associated with shear stresses and strains, as well as with film temperature, is introduced, and a phase diagram is constructed where the noise intensity of the film temperature and the temperature of rubbing surfaces define the domains of sliding, dry, and stick-slip friction. Conditions are found under which stick-slip friction proceeds in the intermittent regime, which is characteristic of self-organized criticality. The stress self-similar distribution, which is provided by temperature fluctuations, is represented with allowance for nonlinear relaxation of stresses and fractional feedbacks in the Lorentz system. Such a fractional scheme is used to construct a phase diagram separating out different types of friction. Based on the study of the fractional Fokker-Planck equation, the conclusion is drawn that stick-slip friction corresponds to the subdiffusion process. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/1620