Scattering line polarization in rotating, optically thick disks

To interpret observations of astrophysical disks it is essential to understand the formation process of the emitted light. If the disk is optically thick, scattering dominated and permeated by a Keplerian velocity field, Non-Local Thermodynamic Equilibrium radiative transfer modeling must be done to compute the emergent spectrum from a given disk model. We investigate Non-local thermodynamic equilibrium polarized line formation in different simple disk models and aim to demonstrate the importance of both radiative transfer effects and scattering as well as the effects of velocity fields. We self-consistently solve the coupled equations of radiative transfer and statistical equilibrium for a two level atom model by means of Jacobi iteration. We compute scattering polarization, that is Q/I and U/I line profiles. The degree of scattering polarization is significantly influenced by the inclination of the disk with respect to observer, but also by the optical thickness of the disk and the presence of rotation. Stokes U shows double-lobed profiles with amplitude which increases with the disk rotation. Our results suggest that the line profiles, especially the polarized ones, emerging from gaseous disks differ significantly from the profiles predicted by simple approximations. The profiles are diverse in shape, but typically symmetric in Stokes Q and antisymmetric in Stokes U. A clear indicator of disk rotation is the presence of Stokes U, which might prove to be a useful diagnostic tool. We also demonstrate that, for moderate rotational velocities, an approximate treatment can be used, where non-local thermodynamic equilibrium radiative transfer is done in the velocity field-free approximation and Doppler shift is applied in the process of spatial integration over the whole emitting surface.Comment: 16 pages; 12 figures; Accepted with revision for A&A. This is the version after first round of referee's suggestion

Spectropolarimetric NLTE inversion code SNAPI

Inversion codes are computer programs that fit a model atmosphere to the observed Stokes spectra, thus retrieving the relevant atmospheric parameters. The rising interest in the solar chromosphere, where spectral lines are formed by scattering, requires developing, testing, and comparing new non-local thermal equilibrium (NLTE) inversion codes. We present a new NLTE inversion code that is based on the analytical computation of the response functions. We named the code SNAPI, which is short for spectropolarimetic NLTE analytically powered inversion. SNAPI inverts full Stokes spectrum in order to obtain a depth-dependent stratification of the temperature, velocity, and the magnetic field vector. It is based on the so-called node approach, where atmospheric parameters are free to vary in several fixed points in the atmosphere, and are assumed to behave as splines in between. We describe the inversion approach in general and the specific choices we have made in the implementation. We test the performance on one academic problem and on two interesting NLTE examples, the Ca\,II\,8542 and Na\,I\,D spectral lines. The code is found to have excellent convergence properties and outperforms a finite-difference based code in this specific implementation by at least a factor of three. We invert synthetic observations of Na lines from a small part of a simulated solar atmosphere and conclude that the Na lines reliably retrieve the magnetic field and velocity in the range $-3<\log \tau < -0.5$.Comment: To appear in A&

Inference of magnetic fields in inhomogeneous prominences

Most of the quantitative information about the magnetic field vector in solar prominences comes from the analysis of the Hanle effect acting on lines formed by scattering. As these lines can be of non-negligible optical thickness, it is of interest to study the line formation process further. We investigate the multidimensional effects on the interpretation of spectropolarimetric observations, particularly on the inference of the magnetic field vector. We do this by analyzing the differences between multidimensional models, which involve fully self-consistent radiative transfer computations in the presence of spatial inhomogeneities and velocity fields, and those which rely on simple one-dimensional geometry. We study the formation of a prototype line in ad hoc inhomogeneous, isothermal 2D prominence models. We solve the NLTE polarized line formation problem in the presence of a large-scale oriented magnetic field. The resulting polarized line profiles are then interpreted (i.e. inverted) assuming a simple 1D slab model. We find that differences between input and the inferred magnetic field vector are non-negligible. Namely, we almost universally find that the inferred field is weaker and more horizontal than the input field. Spatial inhomogeneities and radiative transfer have a strong effect on scattering line polarization in the optically thick lines. In real-life situations, ignoring these effects could lead to a serious misinterpretation of spectropolarimetric observations of chromospheric objects such as prominences.Comment: 11 pages, 9 figure

Analysis of the impact of fruit growing development on the intensity of soil erosion and runoff: Case study of krusevo, bijelo polje, Montenegro

The research has been conducted to analyse the effects of land use change of the impact of fruit growing development on the intensity of soil erosion and runoff in the Study area of Krusevo, Bijelo Polje, Montenegro by using the Intensity of Erosion and Outflow – IntErO model of Spalevic. The required spatial maps, land use, soil and geology were prepared and analysed in GIS environment. The climatic data such as the volume of the torrential rain, average annual air temperature and average annual precipitation were calculated based on meteorological data received from the State Hydrological Institute for the region of Bijelo Polje (Montenegro). The results of land use change between these two periods (2011-2020) shown that the forest increased in the studied region by 1.57%. Specifically, degraded forests increased by 1.02%; Well-constituted forests increased by 0.55%. For the studied area we calculated forested area on 57.26% (2011), and 58.83% (2020). The values for Meadows in the studied area decreased from 2011 to 2020 for 1.67%; and for Pastures for 1.40%. Plough-lands decreased for the observed period for 1.59%. On the other hand, the surface under the Orchards increased by 3.09%, and that represented the shift from the Meadows to the Orchards; the shift from the Pastures to the Forests. This denser vegetation at the studied region for the observed period (increase of the forests and orchards) has led to higher water infiltration rate into the soil and at the same time to decrease of the sediment yield. The value of Z coefficient of 0.462 (2011); 0.461 (2020) indicates slight decrease of erosion processes because of the fruit growing development with shifting the meadows to orchards categorising the processes to the 3rd destruction category. The strength of the erosion process is medium, and according to the erosion type, it is surface erosion. Production of erosion material in the river basin, W year, is calculated on 11327 m3year-1 for 2011; and 11278 m3 year-1 for 2020, what shown the decrease of erosion processes because of the subject fruit growing development. Coefficient of the deposit retention (sediment delivery ratio) is calculated as 0.299 what means that 30% of the total eroded material reaches to the outlet point. Real soil losses, G year, are calculated on 3392 m3 year-1 (2011), and 3377 (2020); Real soil losses per km2, G year km-2, are 262 m3 km-2 year-1 (2011), and 261 m3km-2 year-1 (2020), with the same conclusion in relation to the fruit growing initiatives and the values indicates that the river basin belongs to 5th destruction category; it is a region of very weak erosion. The results showed that the appropriate land management and planning with implementing fruit growing in this area decreases maximum flow rate and also sediment yield. The application of the IntErO model may also be further used to understand the effect of land use change with new establishing of the fruit growing in the river basins on hydrological behaviour, soil erosion and sediment yield process and can be used as a useful tool in similar for fruit growing and soil conservation research

Study of the Electrochemical Oxidation of Reactive Textile Dyes Using Platinum Electrode

Textile industries are widespread in developing countries. Among the various processes in the textile industry, the dyeing process uses large volumes of water for dyeing, fixing and washing. Textile industry wastewater is characterized by intensive color and high chemical oxygen demand (COD) concentrations that discarding of these toxic wastewaters to the environment will cause a major problem. In this study electrochemical oxidation of reactive textile dyes: Reactive Blue 52, Reactive Black 5, Reactive Green 15, and Reactive Yellow 125, using platinum anode was examined. Electrolysis is carried out in electrochemical cell containing membrane which is standard membrane in industry. Membrane separated anodic and cathodic area. Supporting electrolyte was 0.1M sodium sulfate which is also present in real textile effluents. Applied voltage of 6, 12 and 24V, and influence of membrane on electrolysis were examined on model dye (Reactive Blue 52). Highest degradation degree for model dye was achieved at 12V, so electrolysis of other dyes was done on this voltage. COD value of all dyes dropped after 60 minutes of electrolysis below a measurable level ( LT 30mg/L O-2), except Reactive Black 5 whose COD reduction was 57.95% with membrane and 35.28% without membrane applied. Complete decolorization was achieved after 10 to 60 minutes for all dyes. Degradation products of model dye Reactive Blue 52 were monitored with HPLC, and influence of pH on decolorization was also examined on model dye

Constraining the systematics of (acoustic) wave heating estimates in the solar chromosphere

Acoustic wave heating is believed to contribute significantly to the missing energy input required to maintain the solar chromosphere in its observed state. We studied the propagation of waves above the acoustic cutoff in the upper photosphere into the chromosphere with ultraviolet and optical spectral observations interpreted through comparison with three dimensional radiative magnetohydrodynamic (rMHD) \emph{Bifrost} models to constrain the heating contribution from acoustic waves in the solar atmosphere. Sit-and-stare observations taken with the Interface Region Imaging Spectrograph (IRIS) and data from the Interferometric BIdimensional Spectrograph (IBIS) were used to provide the observational basis of this work. We compared the observations with synthetic observables derived from the Bifrost solar atmospheric model. Our analysis of the \emph{Bifrost} simulations show that internetwork and enhanced network regions exhibit significantly different wave propagation properties, which are important for the accurate wave flux estimates. The inferred wave energy fluxes based on our observations are not sufficient to maintain the solar chromosphere. We point out that the systematics of the modeling approaches in the literature lead to differences which could determine the conclusions of this type of studies, based on the same observations.Comment: Accepted for publication in Ap

Study of the Electrochemical Oxidation of Reactive Textile Dyes Using Platinum Electrode

Textile industries are widespread in developing countries. Among the various processes in the textile industry, the dyeing process uses large volumes of water for dyeing, fixing and washing. Textile industry wastewater is characterized by intensive color and high chemical oxygen demand (COD) concentrations that discarding of these toxic wastewaters to the environment will cause a major problem. In this study electrochemical oxidation of reactive textile dyes: Reactive Blue 52, Reactive Black 5, Reactive Green 15, and Reactive Yellow 125, using platinum anode was examined. Electrolysis is carried out in electrochemical cell containing membrane which is standard membrane in industry. Membrane separated anodic and cathodic area. Supporting electrolyte was 0.1M sodium sulfate which is also present in real textile effluents. Applied voltage of 6, 12 and 24V, and influence of membrane on electrolysis were examined on model dye (Reactive Blue 52). Highest degradation degree for model dye was achieved at 12V, so electrolysis of other dyes was done on this voltage. COD value of all dyes dropped after 60 minutes of electrolysis below a measurable level ( LT 30mg/L O-2), except Reactive Black 5 whose COD reduction was 57.95% with membrane and 35.28% without membrane applied. Complete decolorization was achieved after 10 to 60 minutes for all dyes. Degradation products of model dye Reactive Blue 52 were monitored with HPLC, and influence of pH on decolorization was also examined on model dye

Salivary Gland Ultrasonography in Sjögren’s Syndrome: A European Multicenter Reliability Exercise for the HarmonicSS Project

Objectives: Salivary gland ultrasonography (SGUS) is increasingly applied for the management of primary Sjögren's syndrome (pSS). This study aims to: (i) compare the reliability between two SGUS scores; (ii) test the reliability among sonographers with different levels of experience. Methods: In the reliability exercise, two four-grade semi-quantitative SGUS scoring systems, namely De Vita et al. and OMERACT, were tested. The sonographers involved in work-package 7 of the HarmonicSS project from nine countries in Europe were invited to participate. Different levels of sonographers were identified on the basis of their SGUS experience and of the knowledge of the tested scores. A dedicated atlas was used as support for SGUS scoring. Results: Twenty sonographers participated in the two rounds of the reliability exercise. The intra-rater reliability for both scores was almost perfect, with a Light's kappa of 0.86 for the De Vita et al. score and 0.87 for the OMERACT score. The inter-rater reliability for the De Vita et al. and the OMERACT score was substantial with Light's Kappa of 0.75 and 0.77, respectively. Furthermore, no significant difference was noticed among sonographers with different levels of experience. Conclusion: The two tested SGUS scores are reliable for the evaluation of major salivary glands in pSS, and even less-expert sonographers could be reliable if adequately instructed.publishedVersio