Search

The driving and excitation mechanisms of decay-less kink oscillations in coronal loops remain under debate. We aim to quantify and provide simple observational constraints on the photospheric driving of oscillating coronal loops in a few typical active region configurations: sunspot, plage, pores and enhanced-network regions. We then aim to investigate the possible interplay between photospheric driving and properties of kink oscillations in connected coronal loops. We analyse two unique datasets of the corona and photosphere taken at a high resolution during the first coordinated observation campaign between Solar Orbiter and the Swedish 1-m Solar Telescope (SST). A local correlation tracking method is applied on the SST/CRISP data to quantify the photospheric motions at the base of coronal loops. The same loops are then analysed in the corona by exploiting data from the Extreme Ultraviolet Imager on Solar Orbiter, and by using a wavelet analysis to characterize the kink oscillations. Each photospheric region shows dynamics with an overall increase in strength going from pore, plage, enhanced-network to sunspot regions. Differences are also seen in the kink-mode amplitudes of the corresponding coronal loops. This suggests the photosphere is involved in the driving of coronal kink oscillations. However, the few samples available does not allow to further establish the excitation mechanism yet. Despite oscillating coronal loops being anchored in seemingly "static" strong magnetic field regions as seen from coronal EUV observations, photospheric observations provide evidence for a continuous and significant driving at their base. The precise connection between photospheric driving and coronal kink oscillations remains to be further investigated. This study finally provides critical constraints on photospheric driving that can be tested in existing numerical models of coronal loops., Comment: 25 pages, 18 figures, version submitted to A&A on Nov-15 2024, peer-review in progress

Quiet-Sun Ellerman bombs (QSEBs) are small-scale magnetic reconnection events in the lower atmosphere of the quiet Sun. Recent work has shown that a small percentage of them can occur co-spatially and co-temporally to ultraviolet (UV) brightenings in the transition region. We aim to understand how the magnetic topologies associated with closely occurring QSEBs and UV brightenings can facilitate energy transport and connect these events. We used high-resolution H-beta observations from the Swedish 1-m Solar Telescope (SST) and detected QSEBs using k-means clustering. We obtained the magnetic field topology from potential field extrapolations using spectro-polarimetric data in the photospheric Fe I 6173 A line. To detect UV brightenings, we used coordinated and co-aligned data from the Interface Region Imaging Spectrograph (IRIS) and imposed a threshold of 5 sigma above the median background on the (IRIS) 1400 A slit-jaw image channel. We identify four distinct magnetic configurations that associate QSEBs with UV brightenings, including a simple dipole configuration and more complex fan-spine topologies with a three-dimensional (3D) magnetic null point. In the fan-spine topology, the UV brightenings occur near the 3D null point, while QSEBs can be found close to the footpoints of the outer spine, the inner spine, and the fan surface. We find that the height of the 3D null varies between 0.2 Mm to 2.6 Mm, depending on the magnetic field strength in the region. We note that some QSEBs and UV brightenings, though occurring close to each other, are not topologically connected with the same reconnection process. We find that the energy released during QSEBs falls in the range of 10^23 to 10^24 ergs. This study shows that magnetic connectivity and topological features, like 3D null points, are crucial in linking QSEBs in the lower atmosphere with UV brightenings in the transition region., Comment: 14 pages, 13 figures, Accepted for publication in A&A

Context. Since the mechanism of energy release from solar flares is still not fully understood, the study of fine-scale features developing during flares becomes important for progressing towards a consistent picture of the essential physical mechanisms. Aims. We aim to probe the fine structures in flare ribbons at the chromospheric level using high-resolution observations with imaging and spectral techniques. Methods. We present a GOES C2.4 class solar flare observed with the Swedish 1-m Solar Telescope (SST), the Interface Region Imaging Spectrograph (IRIS), and the Atmospheric Imaging Assembly (AIA). The high-resolution SST observations offer spectroscopic data in the H-alpha, Ca II 8542 {\AA}, and H-beta lines, which we use to analyse the flare ribbon. Results. Within the eastern flare ribbon, chromospheric bright blobs were detected and analysed in Ca II 8542 {\AA}, H-alpha, and H-beta wavelengths. A comparison of blobs in H-beta observations and Si IV 1400 {\AA} has also been performed. These blobs are observed as almost circular structures having widths from 140 km-200 km. The intensity profiles of the blobs show a red wing asymmetry. Conclusions. From the high spatial and temporal resolution H-beta observations, we conclude that the periodicity of the blobs in the flare ribbon, which are near-equally spaced in the range 330-550 km, is likely due to fragmented reconnection processes within a flare current sheet. This supports the theory of a direct link between fine-structure flare ribbons and current sheet tearing. We believe our observations represent the highest resolution evidence of fine-structure flare ribbons to date., Comment: 12 pages, 9 figures, accepted for publication in A&A

Poynting flux generated by random shuffling of photospheric magnetic footpoints is transferred through the upper atmosphere of the Sun where the plasma is heated to over 1 MK in the corona. High spatiotemporal resolution observations of the lower atmosphere at the base of coronal magnetic loops are crucial to better understand the nature of the footpoint dynamics and the details of magnetic processes that eventually channel energy into the corona. Here we report high spatial resolution ($\sim$0.1\arcsec) and cadence (1.33 s) hyperspectral imaging of the solar H$\alpha$ line, acquired by the Microlensed Hyperspectral Imager prototype installed at the Swedish 1-m Solar Telescope, that reveal photospheric hot spots at the base of solar coronal loops. These hot spots manifest themselves as H$\alpha$ wing enhancements, occurring on small spatial scales of $\sim$0.2\arcsec, and timescales of less than 100 s. By assuming that the H$\alpha$ wings and the continuum form under the local thermodynamic equilibrium condition, we inverted the H$\alpha$ line profiles and found that the hot spots are compatible with a temperature increase of about 1000 K above the ambient quiet-Sun temperature. The H$\alpha$ wing integrated Stokes $V/I$ maps indicate that hot spots are related to magnetic patches with field strengths comparable to or even stronger than the surrounding network elements. But they do not show the presence of parasitic polarity magnetic field that would support the interpretation that these hot spots are reconnection-driven Ellerman bombs. Therefore, we interpret these features as proxies of locations where convection-driven magnetic field intensification in the photosphere can lead to energy transfer into higher layers. We suggest that such hot spots at coronal loop footpoints may be indicative of the specific locations and onset of energy flux injection into the upper atmosphere., Comment: Published in the Astrophysical Journal

When interpreting spectropolarimetric observations of the solar atmosphere, wavelength variations of the emergent intensity and polarization translate into information on the depth stratification of physical parameters. We aim to quantify how the information content contained in a representative set of polarized spectra depends on the spectral resolution and spectral sampling. We use a state-of-the-art numerical simulation of a sunspot to synthesize polarized spectra of magnetically sensitive neutral iron lines. We then apply various degrees of spectral degradation to the synthetic spectra and analyze the impact on its dimensionality using PCA and wavelet decomposition. Finally, we apply the SIR code to the degraded synthetic data, to assess the effect of spectral resolution on the inferred parameters. We find that regions with strong magnetic fields where convection is suppressed produce less complex Stokes profiles. On the other hand, regions with strong gradients give rise to more complex Stokes profiles that are more affected by spectral degradation. The degradation also makes the inversion problem more ill-defined, so inversion models with a larger number of free parameters overfit and give wrong estimates. The impact of spectral degradation depends on multiple factors, including spectral resolution, noise level, line spread function (LSF) shape, complexity of the solar atmosphere, and the degrees of freedom in our inversion methods. Having a finely sampled spectrum may be more beneficial than achieving a higher signal-to-noise ratio per wavelength bin. Considering the inclusion of different spectral lines that can counter these effects, and calibrating the effective degrees of freedom in modeling strategies, are also important considerations. These strategies are crucial for the accurate interpretation and have the potential to offer more cost-effective solutions., Comment: 15 pages, 15 figures, Submitted to A&A

Full-Stokes polarimetric datasets, originating from slit-spectrograph or narrow-band filtergrams, are routinely acquired nowadays. The data rate is increasing with the advent of bi-dimensional spectropolarimeters and observing techniques that allow long-time sequences of high-quality observations. There is a clear need to go beyond the traditional pixel-by-pixel strategy in spectropolarimetric inversions by exploiting the spatiotemporal coherence of the inferred physical quantities. We explore the potential of neural networks as a continuous representation of the physical quantities over time and space (also known as neural fields), for spectropolarimetric inversions. We have implemented and tested a neural field to perform the inference of the magnetic field vector (approach also known as physics-informed neural networks) under the weak-field approximation (WFA). By using a neural field to describe the magnetic field vector, we can regularize the solution in the spatial and temporal domain by assuming that the physical quantities are continuous functions of the coordinates. We investigated the results in synthetic and real observations of the Ca II 8542 A line. We also explored the impact of other explicit regularizations, such as using the information of an extrapolated magnetic field, or the orientation of the chromospheric fibrils. Compared to the traditional pixel-by-pixel inversion, the neural field approach improves the fidelity of the reconstruction of the magnetic field vector, especially the transverse component. This implicit regularization is a way of increasing the effective signal-to-noise of the observations. Although it is slower than the pixel-wise WFA estimation, this approach shows a promising potential for depth-stratified inversions, by reducing the number of free parameters and inducing spatio-temporal constraints in the solution., Comment: 12 pages, 7 figures, Appendix, Submitted to A&A

Solar jets are collimated plasma ejections along magnetic field lines observed in hot (EUV jets) and cool (chromospheric surges) temperature diagnostics. Their trigger mechanisms and the relationship between hot and cool jets are still not completely understood. We aim to investigate the generation of a sequence of active region solar jets and their evolution from the photospheric to the coronal heights. Using the synergy of high spatial and temporal resolution observations by the SST, along with the SDO, we analyze a sequence of solar jets originating in a mixed polarity region between the leading and following sunspots of an active region. We use a NFFF extrapolation technique for deriving the magnetic field topology of the active region. A mixed polarity region is formed over a long period (24 hours) with persistent magnetic flux emergence. This region has been observed as an arch filament system (AFS) in chromospheric SST observations. In this region, negative polarities surrounded by positive polarities create a fan-surface with a null point at a height of 6 Mm detected in the NFFF extrapolation. SST observations in H-beta spectral line reveal a large flux rope over the AFS and moving from the North to South, causing successive EUV and cool jets to move in the East-West direction and later towards the South along the long open loops. The high resolution SST observations (0.038 arcsec per pixel) resolve the dark area observed at the jet base and reveal the existence of an AFS with an extended cool jet which may be the result of a peeling-like mechanism of the AFS. Based on the combined analysis of SST and AIA observations along with extrapolated magnetic topology, it is suggested that the magnetic reconnection site may move southward by approximately 20 Mm until it reaches a region where the open magnetic field lines are oriented North-South., Comment: 14 pages, 11 figures, accepted for publication in A&A

Quiet Sun Ellerman Bombs (QSEBs) are key indicators of small-scale photospheric magnetic reconnection events. Recent high-resolution observations have shown that they are ubiquitous and that large numbers of QSEBs can be found in the quiet Sun. We aim to understand the impact of QSEBs on the upper solar atmosphere by analysing their spatial and temporal relationship with the UV brightenings observed in transition region diagnostics. We analyse high-resolution H-beta observations from the Swedish 1-m Solar Telescope and utilise k-means clustering to detect 1423 QSEBs in a 51 min time series. We use coordinated and co-aligned observations from the Interface Region Imaging Spectrograph (IRIS) to search for corresponding signatures in the 1400 A slit-jaw image (SJI) channel and in the Si IV 1394 A and Mg II 2798.8 A triplet spectral lines. We identify UV brightenings from SJI 1400 using a threshold of 5$\sigma$ above the median background. We focused on 453 long-lived QSEBs ($>1$ min) and found 67 cases of UV brightenings from SJI 1400 occurring near the QSEBs, both temporally and spatially. Temporal analysis of these events indicates that QSEBs start before UV brightenings in 57 % of cases, while UV brightenings lead in 36 % of instances. The majority of the UV brightenings occur within 1000 km from the QSEBs in the direction of the solar limb. We also identify 21 QSEBs covered by the IRIS slit, with 4 of them showing emissions in both or one of the Si IV 1394 A and Mg II 2798.8 A triplet lines, at distances within 500 km from the QSEBs in the limb direction. We conclude that a small fraction (15 %) of the long-lived QSEBs contribute to localized heating observable in transition region diagnostics, indicating a minimal role in the global heating of the upper solar atmosphere., Comment: 16 pages, 16 figures. Accepted for publication in A&A

Solar jets are collimated plasma flows moving along magnetic field lines and accelerated at low altitude following magnetic reconnection. Several of them originate from anemone-shaped low-lying arcades and the most impulsive ones tend to be relatively wider and display untwisting motions. We aim to establish typical behaviours and observational signatures in the low atmosphere that can occur in response to the coronal development of such impulsive jets. We analysed an observed solar jet associated with a circular flare ribbon, using high-resolution observations from SST coordinated with IRIS and SDO. We related specifically identified features with those developing in a generic 3D line-tied numerical simulation of reconnection driven jets, performed with the ARMS code. We identified three features in the SST observations: the formation of a hook along the circular ribbon, the gradual widening of the jet through the apparent displacement of its kinked edge towards, and not away from the presumed reconnection site, and the falling back of some of the jet plasma towards a footpoint offset from that of the jet itself. The 3D numerical simulation naturally accounts for these features which were not imposed a priori. Our analyses allow to interpret them in the context of the 3D geometry of the asymmetric swirled anemone loops and their sequences of reconnection with ambient coronal loops. Given the relatively-simple conditions in which the observed jet occurred, together with the generic nature of the simulation that comprised minimum assumptions, we predict that the specific features that we identified and interpreted are probably typical of every impulsive jet, Comment: 13 pages, 8 figures, Accepted for publication in Astronomy and Astrophysics

Advancements in instrumentation have revealed a multitude of small-scale EUV events in the solar atmosphere. Our aim is to employ high-resolution magnetograms to gain a detailed understanding of the magnetic origin of such phenomena. We have used coordinated observations from SST, IRIS, and SDO to analyze an ephemeral magnetic flux emergence episode and the following chain of small-scale energetic events. These unique observations clearly link these phenomena together. The high-resolution (0."057/pixel) magnetograms obtained with SST/CRISP allows us to reliably measure the magnetic field at the photosphere and detect the emerging bipole that causes the subsequent eruptive atmospheric events. Notably, this small-scale emergence episode remains indiscernible in the lower resolution SDO/HMI magnetograms (0."5/pixel). We report the appearance of a dark bubble in Ca II K related to the emerging bipole, a sign of the canonical expanding magnetic dome predicted in flux emergence simulations. Evidences of reconnection are also found: first through an Ellerman bomb, and later by the launch of a surge next to a UV burst. The UV burst exhibits a weak EUV counterpart in the coronal SDO/AIA channels. By calculating DEM, its plasma is shown to reach a temperature beyond 1 MK and have densities between the upper chromosphere and transition region. Our study showcases the importance of high-resolution magnetograms to unveil the mechanisms triggering phenomena such as EBs, UV bursts, and surges. This could hold implications for small-scale events akin to those recently reported in EUV using Solar Orbiter. The finding of temperatures beyond 1 MK in the UV burst plasma strongly suggests that we are examining analogous features. Therefore, we signal caution regarding drawing conclusions from full-disk magnetograms that lack the necessary resolution to reveal their true magnetic origin., Comment: Accepted in A&A, 11 pages, 7 figures, 5 movies

Magnetic reconnection in the deep solar atmosphere can give rise to enhanced emission in the Balmer hydrogen lines, a phenomenon known as Ellerman bombs (EBs). It is most common to observe EBs in the H-alpha and H-beta lines. High quality shorter wavelength Balmer line observations of EBs are rare but have the potential to provide the most highly resolved view on reconnection. We evaluate the H-epsilon 3970 A line as an EB diagnostic by analyzing high quality observations in different Balmer lines. Observations of different targets and viewing angles were acquired with the Swedish 1-m Solar Telescope. These observations sample EBs in different environments: active regions, quiet Sun, and the penumbra and moat of a sunspot. We employed an automated detection method for quiet Sun EBs based on k-means clustering. Ellerman bombs in the H-epsilon line show similar characteristics as in the longer wavelength Balmer lines: enhanced intensity as compared to the surroundings, rapid variability, and flame-like morphology. In a 24 min quiet Sun time series, we detected 1674 EBs in the H-epsilon line which is 1.7 times more than in H-beta. The quiet Sun EBs measured in H-epsilon are very similar as in H-beta: they have similar lifetimes, area, brightness, and spatial distribution. Most of the EBs detected in H-epsilon are closer to the limb than their H-beta counterparts. This can be explained by the H-epsilon line core EB emission being formed higher in the atmosphere than the H-beta EB wing emission. We conclude that the H-epsilon line is well suited for studying EBs and consequently probes the dynamics of magnetic reconnection in the solar atmosphere at the smallest scales. Our findings suggests that the deep atmosphere in the quiet Sun may host more than 750,000 reconnection events with EB signature at any time. That is significantly more than what was found in earlier H-beta observations., Comment: accepted for publication in A&A. Movies can be found at https://www.mn.uio.no/astro/english/people/aca/rouppe/movies/

The solar atmosphere is filled with clusters of hot small-scale loops commonly known as Coronal Bright Points (CBPs). These ubiquitous structures stand out in the Sun by their strong X-ray and/or extreme-ultraviolet (EUV) emission for hours to days, which makes them a crucial piece when solving the solar coronal heating puzzle. In addition, they can be the source of coronal jets and small-scale filament eruptions. Here we present a novel 3D numerical model using the Bifrost code that explains the sustained CBP heating for several hours. We find that stochastic photospheric convective motions alone significantly stress the CBP magnetic field topology, leading to important Joule and viscous heating concentrated around the CBP's inner spine at a few megameters above the solar surface. We also detect continuous upflows with faint EUV signal resembling observational dark coronal jets and small-scale eruptions when H$_{\alpha}$ fibrils interact with the reconnection site. We validate our model by comparing simultaneous CBP observations from SDO and SST with observable diagnostics calculated from the numerical results for EUV wavelengths as well as for the H$_{\alpha}$ line using the Multi3D synthesis code. Additionally, we provide synthetic observables to be compared with Hinode, Solar Orbiter, and IRIS. Our results constitute a step forward in the understanding of the many different facets of the solar coronal heating problem., Comment: Accepted in ApJL. 9 pages, 5 figures, 2 movies

We aim to compare and contrast the typical shapes of synthetic Ca II 854.2 nm spectra found in Bifrost simulations having different magnetic activity with the spectral shapes found in a quiet Sun observation from the Swedish 1-m Solar Telescope (SST). We use clustering techniques to extract the typical Ca II 854.2 nm profile shapes synthesized from Bifrost simulations with varying amounts of magnetic activity. We degrade the synthetic profiles to observational conditions and repeat the clustering, and we compare our synthetic results with actual observations. While the mean spectra for our high resolution simulations compare reasonably well with the observations, we find that there are considerable differences between the clusters of observed and synthetic intensity profiles, even after the synthetic profiles have been degraded. The typical absorption profiles from the simulations are both narrower and display a steeper transition from the inner wings to the line core. Furthermore, even in our most quiescent simulation we find a far larger fraction of profiles with local emission around the core, or other exotic profile shapes, than in the observations. Looking into the atmospheric structure for a selected set of synthetic clusters, we find distinct differences in the temperature stratification for the clusters most and least similar to the observations. The narrow and steep profiles are associated with either weak gradients in temperature, or temperatures rising to a local maximum in the line wing forming region before sinking to a minimum in the line core forming region. The profiles that display less steep transitions show extended temperature gradients that are steeper in the range $-3 \lesssim \log \tau_{5000} \lesssim -1$., Comment: Accepted for publication in A&A. Abstract abridged for Arxiv

The S-index is a measure of emission in the CaII H & K lines and is a widely used proxy of stellar magnetic activity. It has been assumed until now that the S-index is mainly affected by bright plage regions in the chromosphere. In particular, the effect of starspots on the S-index has been neglected. In this study we revisit this assumption. For this we analyze high-resolution observations of sunspots recorded in the CaII H spectral line at the Swedish 1-m Solar Telescope and determine the contrast of spots with respect to the quiet surroundings. We find that the CaII H line core averaged over whole sunspots (including superpenumbrae) is brighter than in the quiet surroundings and that the spot contrast in the line core is comparable to the facular contrast. This allows us to get a first estimate of the influence of spots on the S-index. We show that spots increase the S-index. While this increase is quite small for the Sun, it becomes significantly larger for more active stars. Further, we show that the inclusion of the contribution of spots to the S-index strongly affects the relationship between the S-index and stellar disk area coverages by spots and faculae, and present the new relations., Comment: 11 pages, 5 figures, accepted for publication in ApJ Letters

High resolution spectral observations of the lower solar atmosphere (chromosphere and transition region) during coronal heating events, in combination with predictions from models of impulsively heated loops, provide powerful diagnostics of the properties of the heating in active region cores. Here we analyze the first coordinated observations of such events with the Interface Region Imaging Spectrograph (IRIS) and the CHROMospheric Imaging Spectrometer (CHROMIS), at the Swedish 1-m Solar Telescope (SST), which provided extremely high spatial resolution and revealed chromospheric brightenings with spatial dimensions down to ~150km. We use machine learning methods (k-means clustering) and find significant coherence in the spatial and temporal properties of the chromospheric spectra, suggesting, in turn, coherence in the spatial and temporal distribution of the coronal heating. The comparison of IRIS and CHROMIS spectra with simulations suggest that both non-thermal electrons with low energy (low-energy cutoff ~5keV) and direct heating in the corona transported by thermal conduction contribute to the heating of the low atmosphere. This is consistent with growing evidence that non-thermal electrons are not uncommon in small heating events (nano- to micro-flares), and that their properties can be constrained by chromospheric and transition region spectral observations., Comment: Accepted for publication in the Astrophysical Journal. 21 pages, 13 figures

Aims. We aim to understand how Hepsilon is formed in the quiet Sun. In particular, we consider the particular physical mechanism that sets its source function and extinction, how it is formed in different solar structures, and why it is sometimes observed in emission. Methods. We used a 3D radiative magnetohydrodynamic (MHD) simulation that accounts for non-equilibrium hydrogen ionization, run with the Bifrost code. To synthesize Hepsilon and Ca II H spectra, we made use of the RH code, which was modified to take into account the non-equilibrium hydrogen ionization. To determine the dominant terms in the H${\epsilon}$ source function, we adopted a multi-level description of the source function. Using synthetic spectra and simulation, we studied the contribution function to the relative line absorption or emission and compared it with atmospheric quantities at different locations. Results. Our multi-level source function description suggests that the H${\epsilon}$ source function is dominated by interlocking, with the dominant interlocking transition being through the ground level, populating the upper level of H${\epsilon}$ via the Lyman series. This makes the H${\epsilon}$ source function partly sensitive to temperature. The H${\epsilon}$ extinction is set by Lyman-${\alpha}$. In some cases, this temperature dependence gives rise to H${\epsilon}$ emission, indicating heating. High-resolution observations reveal that H${\epsilon}$ is not just a weak absorption line. Regions with H${\epsilon}$ in emission are especially interesting to detect small-scale heating events in the lower solar atmosphere, such as Ellerman bombs. Thus, H${\epsilon}$ can be an important new diagnostic tool for studies of heating in the solar atmosphere, augmenting the diagnostic potential of Ca II H when observed simultaneously

Nanoflare heating through small-scale magnetic reconnection events is one of the prime candidates to explain heating of the solar corona. However, direct signatures of nanoflares are difficult to determine, and unambiguous observational evidence is still lacking. Numerical models that include accelerated electrons and can reproduce flaring conditions are essential in understanding how low-energetic events act as a heating mechanism of the corona, and how such events are able to produce signatures in the spectral lines that can be detected through observations. We investigate the effects of accelerated electrons in synthetic spectra from a 3D radiative magnetohydrodynamics simulation to better understand small-scale heating events and their impact on the solar atmosphere. We synthesised the chromospheric Ca II and Mg II lines and the transition region Si IV resonance lines from a quiet Sun numerical simulation that includes accelerated electrons. We calculated the contribution function to the intensity to better understand how the lines are formed, and what factors are contributing to the detailed shape of the spectral profiles. The synthetic spectra are highly affected by variations in temperature and vertical velocity. Beam heating exceeds conductive heating at the heights where the spectral lines form, indicating that the electrons should contribute to the heating of the lower atmosphere and hence affect the line profiles. However, we find that it is difficult to determine specific signatures from the non-thermal electrons due to the complexity of the atmospheric response to the heating in combination with the relatively low energy output (~1e21 erg/s). Even so, our results contribute to understanding small-scale heating events in the solar atmosphere, and give further guidance to future observations.

We analysed state-of-the-art observations of the solar atmosphere to investigate the dependence of the \ca brightness of several solar features on spectral bandwidth and spatial resolution of the data. Specifically, we study data obtained at the Swedish Solar Telescope with the CRiSP and CHROMIS instruments. The analyzed data, which are characterized by spectral bandwidth of 0.12 \AA \ and spatial resolution of 0.078\arcsec, were acquired close to disc center by targeting a quiet Sun area and an active region. We convolved the original observations with Gaussian kernels to degrade their spectral bandwidth and spatial resolution to the instrumental characteristics of the most prominent series of \ca observations available to date. We then studied the effect of data degradation on the observed regions and on parameters derived from \ca line measurements that are largely employed as diagnostics of the solar and stellar chromospheres. We find that the effect of degrading the spectral resolution of \ca observations and line profiles depends on both the employed bandwidth and observed solar region. Besides, we found that the spatial degradation impacts the data characterized by a broad bandwidth to a larger extent compared to those acquired with a narrow band. However, the appearance of the observed solar regions is only slightly affected by the spatial resolution of data with bandwidths up to 1 \AA \ and in the range [3,10] \AA. Finally, we derived relationships that can be used to intercalibrate results from observations taken with different instruments in diverse regions of the solar atmosphere., Comment: 26 pages, 17 figures, ApJ accepted

Fabry-P\'erot interferometers (FPIs) have become very popular in solar observations because they offer a balance between cadence, spatial resolution, and spectral resolution through a careful design of the spectral sampling scheme according to the observational requirements of a given target. However, an efficient balance requires knowledge of the expected target conditions, the properties of the chosen spectral line, and the instrumental characteristics. Our aim is to find a method that allows finding the optimal spectral sampling of FPI observations in a given spectral region. In this study, we propose a technique based on a sequential selection approach where a neural network is used to predict the spectrum (or physical quantities, if the model is known) from the information at a few points. Only those points that contain relevant information and improve the model prediction are included in the sampling scheme. The method adapts the separation of the points according to the spectral resolution of the instrument, the typical broadening of the spectral shape, and the typical Doppler velocities. The experiments using the CaII 8542 A line show that the resulting wavelength scheme naturally places more points in the core than in the wings, consistent with the sensitivity of the spectral line at each wavelength interval. The method can also be used as an accurate interpolator, to improve the inference of the magnetic field when using the weak-field approximation. Overall, this method offers an objective approach for designing new instrumentation or observing proposals with customized configurations for specific targets. This is particularly relevant when studying highly dynamic events in the solar atmosphere with a cadence that preserves spectral coherence without sacrificing much information., Comment: 8 pages, 7 figures, accepted for publication in A&A

Magnetic reconnection in the deep solar atmosphere can give rise to enhanced emission in the Balmer hydrogen lines, a phenomenon referred to as Ellerman bombs. To effectively trace magnetic reconnection below the canopy of chromospheric fibrils, we analyzed unique spectroscopic observations of Ellerman bombs in the H-alpha line. We analyzed a 10 min dataset of a young emerging active region observed with the prototype of the Microlensed Hyperspectral Imager (MiHI) at the Swedish 1-m Solar Telescope (SST). The MiHI instrument is an integral field spectrograph that is capable of achieving simultaneous ultra-high resolution in the spatial, temporal and spectral domains. With the combination of the SST adaptive optics system and image restoration techniques, MiHI can deliver diffraction limited observations if the atmospheric seeing conditions allow. The dataset samples the H-alpha line over 4.5 A with 10 mA/pix, with 0.065"/pix over a field of view of 8.6" x 7.7", and at a temporal cadence of 1.33s. This constitutes a hyperspectral data cube that measures 132 x 118 spatial pixels, 456 spectral pixels, and 455 time steps. There were multiple sites with Ellerman bomb activity associated with strong magnetic flux emergence. The Ellerman bomb activity is very dynamic, showing rapid variability and small-scale substructure. We found a number of plasmoid-like blobs with full-width-half-maximum sizes between 0.1" - 0.4" and moving with apparent velocities between 14 and 77 km/s. Some of these blobs have Ellerman bomb spectral profiles with a single peak at a Doppler offset between 47 and 57 km/s. Our observations support the idea that fast magnetic reconnection in Ellerman bombs is mediated by the formation of plasmoids. These MiHI observations demonstrate that a micro-lens based integral field spectrograph is capable of probing fundamental physical processes in the solar atmosphere., Comment: accepted for publication in A&A. Movies can be found at https://www.mn.uio.no/astro/english/people/aca/rouppe/movies/

Coronal Bright Points (CBPs) are sets of small-scale coronal loops, connecting opposite magnetic polarities, primarily characterized by their enhanced extreme-ultraviolet (EUV) and X-ray emission. Being ubiquitous, they are thought to play an important role in heating the solar corona. We aim at characterizing the barely-explored chromosphere underneath CBPs, focusing on the related spicular activity and on the effects of small-scale magnetic flux emergence on CBPs. We used high-resolution observations of a CBP in H$\beta$ and Fe I 617.3 nm from the Swedish 1-m Solar Telescope (SST) in coordination with the Solar Dynamics Observatory (SDO). This work presents the first high-resolution observation of spicules imaged in H$\beta$. The spicules were automatically detected using advanced image processing techniques, which were applied to the Dopplergrams derived from H$\beta$. Here we report their abundant occurrence close to the CBP ``footpoints", and find that the orientation of such spicules is aligned along the EUV loops, indicating that they constitute a fundamental part of the whole CBP magnetic structure. Spatio-temporal analysis across multiple channels indicates that there are coronal propagating disturbances associated with the studied spicules, producing transient EUV intensity variations of the individual CBP loops. Two small-scale flux emergence episodes appearing below the CBP were analyzed; one of them leading to quiet-sun Ellerman bombs and enhancing the nearby spicular activity. This paper presents unique evidence of the tight coupling between the lower and upper atmosphere of a CBP, thus helping to unravel the dynamic phenomena underneath CBPs and their impact on the latter., Comment: Accepted for publication in the Astrophysical Journal. 16 pages, 11 figures. Animations embedded

Short-lived (100s or less), sub-arcsec to a couple of arcsec size features of enhanced brightenings in the narrowband images at the $\mathrm{H_{2V}}$ and $\mathrm{K_{2V}}$ positions of the Ca II H and K lines in the quiet Sun are known as bright grains. With simultaneous observations of a quiet Sun internetwork region in the Fe I 6173 {\AA}, Ca II 8542 {AA}, and Ca II K lines acquired by the CRisp Imaging Spectro-Polarimeter and the CHROMospheric Imaging Spectrometer instruments on the Swedish 1-m Solar Telescope, we performed multi-line non-local thermodynamic equilibrium inversions using the STockholm inversion Code to infer the time-varying stratified atmosphere's physical properties such as the temperature, line-of-sight (LOS) velocity, and microturbulence. The Ca II K profiles of bright grains show enhancement in the $\mathrm{K_{2V}}$ peak intensities with absence of the $\mathrm{K_{2R}}$ features. At the time of maximum enhancement in the $\mathrm{K_{2V}}$ peak intensities, we found average enhancements in temperature at lower chromospheric layers (at $\log\tau_{500}$ $\simeq$ $-$4.2) of about 1.1 kK with maximum enhancement of about 4.5 kK. These temperature enhancements are colocated with upflows, as strong as $-$6 $\mathrm{km\;s^{-1}}$, in the direction of the LOS. The LOS velocities at upper chromospheric layers at $\log\tau_{500}$ < $-$4.2 show consistent downflows greater than $+$8 $\mathrm{km\;s^{-1}}$. The retrieved value of microturbulence in the atmosphere of bright grains is negligible at chromospheric layers. The study provides observational evidence to support the interpretation that the bright grains observed in narrowband images at the $\mathrm{H_{2V}}$ and $\mathrm{K_{2V}}$ positions of the Ca II H and K lines are manifestations of upward propagating acoustic shocks against a background of downflowing atmospheres., Comment: 23 pages, 12 figures, accepted to be published in Astronomy and Astrophysics on 3rd October, 2022

Computer-aided methods have shown added value for diagnosing and predicting brain disorders and can thus support decision making in clinical care and treatment planning. This chapter will provide insight into the type of methods, their working, their input data - such as cognitive tests, imaging and genetic data - and the types of output they provide. We will focus on specific use cases for diagnosis, i.e. estimating the current 'condition' of the patient, such as early detection and diagnosis of dementia, differential diagnosis of brain tumours, and decision making in stroke. Regarding prediction, i.e. estimation of the future 'condition' of the patient, we will zoom in on use cases such as predicting the disease course in multiple sclerosis and predicting patient outcomes after treatment in brain cancer. Furthermore, based on these use cases, we will assess the current state-of-the-art methodology and highlight current efforts on benchmarking of these methods and the importance of open science therein. Finally, we assess the current clinical impact of computer-aided methods and discuss the required next steps to increase clinical impact.

We analyzed spectropolarimetric data from the Swedish 1-meter Solar Telescope to investigate physical properties of small-scale magnetic cancellations in the quiet Sun photosphere. Specifically, we looked at the full Stokes polarization profiles along the Fe I 557.6 nm and of the Fe I 630.1 nm lines measured by CRisp Imaging SpectroPolarimeter (CRISP) to study temporal evolution of the line-of-sight (LOS) magnetic field during 42.5 minutes of quiet Sun evolution. From this magnetogram sequence, we visually identified 38 cancellation events. We then used Yet Another Feature Tracking Algorithm (YAFTA) to characterize physical properties of these magnetic cancellations. We found on average $1.6\times10^{16}$ Mx of magnetic flux cancelled in each event with an average cancellation rate of $3.8\times10^{14}$ Mx s$^{-1}$. The derived cancelled flux is associated with strong downflows, with an average speed of $V_\mathrm{LOS}\approx1.1$ km s$^{-1}$. Our results show that the average lifetime of each event is $9.2$ minutes with an average $44.8\%$ of initial magnetic flux being cancelled. Our estimates of magnetic fluxes provide a lower limit since studied magnetic cancellation events have magnetic field values that are very close to the instrument noise level. We observed no horizontal magnetic fields at the cancellation sites and therefore can not conclude whether the events are associated structures that could cause magnetic reconnection., Comment: 19 pages, 18 figures, 2 tables, accepted into ApJ on 06/08/2022

Although machine learning (ML) has shown promise in numerous domains, there are concerns about generalizability to out-of-sample data. This is currently addressed by centrally sharing ample, and importantly diverse, data from multiple sites. However, such centralization is challenging to scale (or even not feasible) due to various limitations. Federated ML (FL) provides an alternative to train accurate and generalizable ML models, by only sharing numerical model updates. Here we present findings from the largest FL study to-date, involving data from 71 healthcare institutions across 6 continents, to generate an automatic tumor boundary detector for the rare disease of glioblastoma, utilizing the largest dataset of such patients ever used in the literature (25,256 MRI scans from 6,314 patients). We demonstrate a 33% improvement over a publicly trained model to delineate the surgically targetable tumor, and 23% improvement over the tumor's entire extent. We anticipate our study to: 1) enable more studies in healthcare informed by large and diverse data, ensuring meaningful results for rare diseases and underrepresented populations, 2) facilitate further quantitative analyses for glioblastoma via performance optimization of our consensus model for eventual public release, and 3) demonstrate the effectiveness of FL at such scale and task complexity as a paradigm shift for multi-site collaborations, alleviating the need for data sharing., Comment: federated learning, deep learning, convolutional neural network, segmentation, brain tumor, glioma, glioblastoma, FeTS, BraTS

Magnetic reconnection in the deep solar atmosphere can give rise to enhanced emission in the Balmer hydrogen lines, a phenomenon referred to as Ellerman bombs. Recent high quality H$\beta$ observations indicate that Ellerman bombs are more common than previously thought and it was estimated that at any time about half a million Ellerman bombs are present in the quiet Sun. We performed an extensive statistical characterization of the quiet Sun Ellerman bombs (QSEBs) in these new H$\beta$ observations. We analyzed a 1 h dataset of quiet Sun observed with the Swedish 1-m Solar Telescope that consists of spectral imaging in the H$\beta$ and H$\alpha$ lines, as well as spectropolarimetric imaging in Fe I 617.3 nm. We detected a total of 2809 QSEBs. The lifetime varies between 9 s and 20.5 min with a median of 1.14 min. The maximum area ranges between 0.0016 and 0.2603 Mm$^2$ with a median of 0.018 Mm$^2$. A subset (14%) of the QSEBs display enhancement of the H$\beta$ line core. On average, the line core brightening appears 0.88 min after the onset of brightening in the wings, and the distance between these brightenings is 243 km. This gives rise to an apparent propagation speed ranging between $-$14.3 and +23.5 km s$^{-1}$, with an average that is upward propagating at +4.4 km $^{-1}$. The average orientation is nearly parallel to the limbward direction. QSEBs are nearly uniformly distributed over the field of view but we find empty areas with the size of mesogranulation. QSEBs are located more frequent near the magnetic network where they are often bigger, longer lived and brighter. We conclude that QSEBs are ubiquitous in quiet Sun and appear everywhere except in areas of mesogranular size with weakest magnetic field ($B_{\rm{LOS}}\lesssim50$~G). Our observations support the interpretation of reconnection along vertically extended current sheets., Comment: Accepted for publication in A&A

We analyze an 'up-the-gradient' model for the formation of transport channels of the phytohormone auxin, through auxin-mediated polarization of the PIN1 auxin transporter. We show that this model admits a family of travelling wave solutions that is parameterized by the height of the auxin-pulse. We uncover scaling relations for the speed and width of these waves and verify these rigorous results with numerical computations. In addition, we provide explicit expressions for the leading-order wave profiles, which allows the influence of the biological parameters in the problem to be readily identified. Our proofs are based on a generalization of the scaling principle developed by Friesecke and Pego to construct pulse solutions to the classic Fermi-Pasta-Ulam-Tsingou model, which describes a one-dimensional chain of coupled nonlinear springs.

Heating signatures from small-scale magnetic reconnection events in the solar atmosphere have proven to be difficult to detect through observations. Numerical models that reproduce flaring conditions are essential in the understanding of how nanoflares may act as a heating mechanism of the corona. We study the effects of non-thermal electrons in synthetic spectra from 1D hydrodynamic RADYN simulations of nanoflare heated loops to investigate the diagnostic potential of chromospheric emission from small-scale events. The Mg II h and k, Ca II H and K, Ca II 854.2 nm, H-alpha and H-beta chromospheric lines were synthesised from various RADYN models of coronal loops subject to electron beams of nanoflare energies. The contribution function to the line intensity was computed to better understand how the atmospheric response to the non-thermal electrons affects the formation of spectral lines and the detailed shape of their spectral profiles. The spectral line signatures arising from the electron beams highly depend on the density of the loop and the lower cutoff energy of the electrons. Low-energy (5 keV) electrons deposit their energy in the corona and transition region, producing strong plasma flows that cause both redshifts and blueshifts of the chromospheric spectra. Higher-energy (10 and 15 keV) electrons deposit their energy in the lower transition region and chromosphere, resulting in increased emission from local heating. Our results indicate that effects from small-scale events can be observed with ground-based telescopes, expanding the list of possible diagnostics for the presence and properties of nanoflares.

Cu-NH3 bearing effluents arise from electroplating and metal extraction industries, requiring innovative and sustainable Cu recovery technologies to reduce their adverse environmental impact. CO32- and Zn are often co-occurring, and thus, selective Cu recovery from these complex liquid streams is required for economic viability. This study assessed 23 sustainable biosorbents classified as tannin-rich, lignin-rich, chitosan/chitin, dead biomass, macroalgae or biochar for their Cu adsorption capacity and selectivity in a complex NH3-bearing bioleachate. Under a preliminary screen with 12 mM Cu in 1 M ammoniacal solution, most biosorbents showed optimal Cu adsorption at pH 11, with pinecone remarkably showing high removal efficiencies (up to 68%) at all tested pH values. Further refinements on select biosorbents with pH, contact time, and presence of NH3, Zn and CO32- showed again that pinecone has a high maximum adsorption capacity (1.07 mmol g-1), worked over pH 5-12 and was Cu-selective with 3.97 selectivity quotient (KCu/Zn). Importantly, pinecone performance was maintained in a real Cu/NH3/Zn/CO32- bioleachate, with 69.4% Cu removal efficiency. Unlike synthetic adsorbents, pinecones require no pre-treatment, which together with its abundance, selectivity, and efficiency without the need for prior NH3 removal, makes it a competitive and sustainable Cu biosorbent for complex Cu-NH3 bearing streams. Overall, this study demonstrated the potential of integrating bioleaching and biosorption as a clean Cu recovery technology utilizing only sustainable resources (i.e., bio-lixiviant and biosorbents). This presents a closed-loop approach to Cu extraction and recovery from wastes, thus effectively addressing elemental sustainability., Comment: 49 pages, 6 figures, 2 tables, 7 supplementary figures, 2 supplementary tables

Radiomics uses quantitative medical imaging features to predict clinical outcomes. Currently, in a new clinical application, finding the optimal radiomics method out of the wide range of available options has to be done manually through a heuristic trial-and-error process. In this study we propose a framework for automatically optimizing the construction of radiomics workflows per application. To this end, we formulate radiomics as a modular workflow and include a large collection of common algorithms for each component. To optimize the workflow per application, we employ automated machine learning using a random search and ensembling. We evaluate our method in twelve different clinical applications, resulting in the following area under the curves: 1) liposarcoma (0.83); 2) desmoid-type fibromatosis (0.82); 3) primary liver tumors (0.80); 4) gastrointestinal stromal tumors (0.77); 5) colorectal liver metastases (0.61); 6) melanoma metastases (0.45); 7) hepatocellular carcinoma (0.75); 8) mesenteric fibrosis (0.80); 9) prostate cancer (0.72); 10) glioma (0.71); 11) Alzheimer's disease (0.87); and 12) head and neck cancer (0.84). We show that our framework has a competitive performance compared human experts, outperforms a radiomics baseline, and performs similar or superior to Bayesian optimization and more advanced ensemble approaches. Concluding, our method fully automatically optimizes the construction of radiomics workflows, thereby streamlining the search for radiomics biomarkers in new applications. To facilitate reproducibility and future research, we publicly release six datasets, the software implementation of our framework, and the code to reproduce this study., Comment: 33 pages, 4 figures, 4 tables, 2 supplementary figures, 3 supplementary table, submitted to Medical Image Analysis; revision

Spectroscopic observations of the emission lines formed in the solar transition region (TR) commonly show persistent downflows of the order of 10--15 km/s. The cause of such downflows, however, is still not fully clear and has remained a matter of debate. We aim to understand the cause of such downflows by studying the coronal and TR responses to the recently reported chromospheric downflowing rapid red shifted excursions (RREs), and their impact on heating the solar atmosphere. We have used two sets of coordinated data from SST, IRIS, and SDO for analyzing the response of the downflowing RREs in the TR and corona. To provide theoretical support, we use an already existing 2.5D MHD simulation of spicules performed with the Bifrost code. We find ample occurrences of downflowing RREs and show several examples of their spatio-temporal evolution, sampling multiple wavelength channels ranging from the cooler chromospheric to hotter coronal channels. These downflowing features are thought to be likely associated with the returning components of the previously heated spicular plasma. Furthermore, the TR Doppler shifts associated with them are close to the average red shifts observed in this region which further implies that these flows could (partly) be responsible for the persistent downflows observed in the TR. We also propose two mechanisms (a typical upflow followed by a downflow and downflows along a loop), from the perspective of numerical simulation, that could explain the ubiquitous occurrence of such downflows. A detailed comparison between the synthetic and observed spectral characteristics, reveals a distinctive match, and further suggests an impact on the heating of the solar atmosphere. We present evidence that suggests that at least some of the downflowing RREs are the chromospheric counterparts of the TR and lower coronal downflows., Comment: 20 pages, 10 figures, accepted for publication in Astronomy and Astrophysics. Abstract abridged due to arXiv requirements

By circumventing the optical diffraction limit, super-resolved fluorescence microscopies enable the study of larger cellular structures and molecular assemblies. However, fluorescence nanoscopy currently lacks the spatiotemporal resolution to resolve distances on the size of individual molecules and reveal the conformational fine structure and dynamics of molecular complexes. Here we establish FRET nanoscopy by combining colocalization STED microscopy with multiparameter FRET spectroscopy. We simultaneously localize donor and acceptor dyes of single FRET pairs with nanometer resolution and quantitatively measure intramolecular distances with sub-nanometer precision over a large dynamic range. While FRET provides isotropic 3D distance information, colocalization measures the projected distance onto the image plane. The combined information allows us to directly determine its 3D orientation using Pythagoras's theorem. Studying two DNA model systems and the human guanylate binding protein hGBP1, we demonstrate that FRET nanoscopy unravels the interplay between their spatial organization and local molecular conformation in a complex environment., Comment: Main Text (34 pages, 6 figures) with Supporting Information (90 pages, 29 figures, 20 tables)

The physical conditions leading the sunspot penumbra decay are poorly understood so far. We investigate the photospheric magnetic and velocity properties of a sunspot penumbra during the decay phase to advance the current knowledge of the conditions leading to this process. A penumbral decay was observed with the CRISP instrument at the Swedish 1m Solar Telescope on 2016 September 4 and 5 in active region NOAA 12585. During these days, full-Stokes spectropolarimetric scans along the Fe I 630 nm line pair were acquired over more than one hour. We inverted these observations with the VFISV code in order to obtain the evolution of the magnetic and velocity properties. We complement the study with data from instruments onboard the Solar Dynamics Observatory and Hinode space missions. The studied penumbra disappears progressively in both time and space. The magnetic flux evolution seems to be linked to the presence of Moving Magnetic Features (MMFs). Decreasing Stokes V signals are observed. Evershed flows and horizontal fields were detected even after the disappearance of the penumbral sector. The analyzed penumbral decay seems to result from the interaction between opposite polarity fields in type III MMFs and penumbra, while the presence of overlying canopies rules the evolution in the different penumbral sectors., Comment: 13 pages, 11 figures, accepted for publication in A&A

This paper describes the development of and first experiences with 'Design Your Life': a novel method aimed at user-initiated design of technologies supporting young autistic adults in independent living. A conceptual, phenomenological background resulting in four core principles is described. Taking a practice-oriented Research-through-Design approach, three co-design case studies were conducted, in which promising methods from the co-design literature with the lived experiences and practical contexts of autistic young adults and their caregivers is contrasted. This explorative inquiry provided some first insights into several design directions of the Design Your Life-process. In a series of new case studies that shall follow, the Design Your Life-method will be iteratively developed, refined and ultimately validated in practice.

The problem of tumor growth prediction is challenging, but promising results have been achieved with both model-driven and statistical methods. In this work, we present a framework for the evaluation of growth predictions that focuses on the spatial infiltration patterns, and specifically evaluating a prediction of future growth. We propose to frame the problem as a ranking problem rather than a segmentation problem. Using the average precision as a metric, we can evaluate the results with segmentations while using the full spatiotemporal prediction. Furthermore, by separating the model goodness-of-fit from future predictive performance, we show that in some cases, a better fit of model parameters does not guarantee a better the predictive power.

Ellerman bombs are regions with enhanced Balmer line wing emission and mark magnetic reconnection in the deep solar atmosphere in active regions and quiet Sun. They are often found in regions where opposite magnetic polarities are in close proximity. Recent high resolution observations suggest that Ellerman bombs are more prevalent than thought before. We aim to determine the occurrence of Ellerman bombs in the penumbra of sunspots. We analyze high spatial resolution observations of sunspots in the Balmer H-alpha and H-beta lines as well as auxiliary continuum channels obtained with the Swedish 1-m Solar Telescope and apply the k-means clustering technique to systematically detect and characterize Ellerman Bombs. Features with all the defining characteristics of Ellerman bombs are found in large numbers over the entire penumbra. The true prevalence of these events is only fully appreciated in the H-beta line due to highest spatial resolution and lower chromospheric opacity. We find that the penumbra hosts some of the highest Ellerman bomb densities, only surpassed by the moat in the immediate surroundings of the sunspot. Some penumbral Ellerman bombs show flame morphology and rapid dynamical evolution. Many penumbral Ellerman bombs are fast moving with typical speed of 3.7 km/s and sometimes more than 10 km/s. Many penumbral Ellerman bombs migrate from the inner to the outer penumbra over hundreds of km and some continue moving beyond the outer penumbral boundary into the moat. Many penumbral Ellerman bombs are found in the vicinity of regions with opposite magnetic polarity. We conclude that reconnection is a near continuous process in the low atmosphere of the penumbra of sunspots as manifest in the form of penumbral Ellerman bombs. These are so prevalent that they may be a major sink of sunspot magnetic energy., Comment: accepted for publication in A&A. Movies can be found at https://www.mn.uio.no/astro/english/people/aca/rouppe/movies/

High-speed downflows have been observed in the solar transition region (TR) and lower corona for many decades. Despite their abundance, it has been hard to find signatures of such downflows in the solar chromosphere. In this work, we target an enhanced network region that shows ample occurrences of rapid spicular downflows in the \halpha\ spectral line that could potentially be linked to high-speed TR downflowing counterparts. We used the $k$-means algorithm to classify the spectral profiles of on-disk spicules in \halpha{} and \cak{} data observed from the Swedish 1-m Solar Telescope (SST) and employed an automated detection method based on advanced morphological image processing operations to detect such downflowing features, in conjunction with rapid blue-shifted and red-shifted excursions (RBEs and RREs). We report the existence of a new category of RREs (termed as downflowing RRE) for the first time that, contrary to earlier interpretation, are associated with chromospheric field-aligned downflows moving towards the strong magnetic field regions. Statistical analysis performed on nearly 20,000 RBEs and 15,000 RREs (including the downflowing counterparts), detected in our 97~min long dataset, shows that the downflowing RREs are very similar to RBEs and RREs except for their oppositely directed plane-of-sky motion. Furthermore, we also find that RBEs, RREs and downflowing RREs can be represented by a wide range of spectral profiles with varying Doppler offsets, and \halpha{} line core widths, both along and perpendicular to the spicule axis, that causes them to be associated with multiple substructures that evolve together. We speculate that these rapid plasma downflows could well be the chromospheric counterparts of the commonly observed TR downflows., Comment: 24 pages, 16 figures. Accepted for publication in Astronomy & Astrophysics. Some of the figures have been compressed to comply with arXiv requirements

Accurate characterization of glioma is crucial for clinical decision making. A delineation of the tumor is also desirable in the initial decision stages but is a time-consuming task. Leveraging the latest GPU capabilities, we developed a single multi-task convolutional neural network that uses the full 3D, structural, pre-operative MRI scans to can predict the IDH mutation status, the 1p/19q co-deletion status, and the grade of a tumor, while simultaneously segmenting the tumor. We trained our method using the largest, most diverse patient cohort to date containing 1508 glioma patients from 16 institutes. We tested our method on an independent dataset of 240 patients from 13 different institutes, and achieved an IDH-AUC of 0.90, 1p/19q-AUC of 0.85, grade-AUC of 0.81, and a mean whole tumor DICE score of 0.84. Thus, our method non-invasively predicts multiple, clinically relevant parameters and generalizes well to the broader clinical population.