Diffusion MRI of the brain enables to quantify white matter fiber orientations noninvasively. Several approaches have been proposed to estimate such characteristics from diffusion MRI data with spherical deconvolution being one of the most widely used methods. Spherical deconvolution requires to define––or derive from the data––a response function, which is used to compute the fiber orientation distribution (FOD). Different characteristics of the response function are expected to affect the FOD computation and the subsequent fiber tracking.In this work, we explored the effects of inaccuracies in the shape factors of the response function on the FOD characteristics.With simulations, we show that the apparent fiber density could be doubled in the presence of underestimated shape factors in the response functions, whereas the overestimation of the shape factor will cause more spurious peaks in the FOD, especially when the signal‐to‐noise ratio is below 15. Moreover, crossing fiber populations with a separation angle smaller than 60° were more sensitive to inaccuracies in the response function than fiber populations with more orthogonal separation angles. Results with in vivo data demonstrate angular deviations in the FODs and spurious peaks as a result of modified shape factors of the response function, while the reconstruction of the main parts of fiber bundles is well preserved.This work sheds light on how specific aspects of the response function shape can affect the estimated FODs, and highlights the importance of a proper calibration/definition of the response function. Diffusion MRI allows to characterize tissue microstructure in vivo and noninvasively by measuring the anisotropic diffusion of water molecules.SD requires an appropriate response function as an input to estimate the FOD.In order to compare intersubject AFD, Raffelt and colleaguesPrevious studies have partially investigated the effect of improperly calibrated response functions on the FOD characteristics and fiber tracking. TournierIn this manuscript, we seek to disentangle the effect of the axial and radial component of the response function on the FOD characteristics and, complementing earlier studies,In the following sections, we give a brief background on (constrained) SD methods to reconstruct the FOD, outline the simulation experiments, and introduce the shape and scaling factor that characterize the response function, and present the parameter settings used in these simulations. Finally, the in vivo data experiments are described.Recent studies showed that crossing fibers account for over 90% of white matter voxels.Constrained spherical deconvolution (CSD) assumes that the diffusion MRI signals can be expressed as the spherical convolution of a fiber response function with the FODs in the spherical harmonics basis, thus also assuming the validity of the response function in all voxels. The response function represents the diffusion‐weighted signal of an SFP. Spherical harmonics form a complete basis on the sphere. The diffusion MRI signal is smooth and can be adequately represented using truncated SH series.The FODs are used to infer information on the orientation of the fiber pathways under the assumption that the FOD peak orientations coincide with the underlying fiber directions. In addition to directional information, the magnitudes of the FOD are used to compute additional metrics, such as AFDThe response function used in the CSD process can be either simulated or derived directly from the data. Following the latter approach, which is more common, voxels that have a high chance of containing SFPs are used to calibrate the response function. A straightforward approach to numerically implement the concept of an SFP is to threshold, for instance FA, above a predefined value. However, the choice of FA threshold is not trivial and can cause inaccuracies in the response function estimation.The choice of the fiber response function has potential impacts on the peak directions and magnitudes of the FOD.Parker et al.D associated with the underlying fiber population is expressed by an axially symmetric diffusion tensor, whose first eigenvector is in parallel with the z‐axis in the reference coordinate frame, then D can be written as:α and β are the axial and radial diffusivity of the SFP,  is the polar angle set between the fiber orientation and applied gradient. Given the axial symmetry property of the diffusion tensor, Equation  from each fiber population is a function of D, then the diffusion‐weighted signal S can be rewritten as:S0 is the nondiffusion‐weighted signal and b is the b‐value that represents the strength of diffusion weighting. Combining Equations  the shape factor α of the response function, by varying only the axial diffusivity with a fixed radial diffusivity, to keep K constant; and (2) the scaling factor K of the response function, by changing simultaneously the axial and radial diffusivity, to not alter the shape factor α. We can then study the effects of R on FOD characteristics, by selectively introducing a discrepancy into the shape or the scale of a simulated single‐fiber signal with respect to the response function.According to Equation , for a giS(θ), where i denotes the ith fiber population. The signal SDW generated by a crossing fiber configuration can then be described by:if is the signal fraction of each fiber population, n is the total number of fiber populations intercrossing the voxel, and i(θ) is the angle between the applied gradient and the ith fiber population. In our work, we focus on configurations of two crossing fiber populations, but the equations of generating the diffusion‐weighted signals can also be extended to analyze the FOD characteristics for more than two fiber populations.We model the diffusion‐weighted signal within a voxel as the sum of multiple compartments measured from each fiber population. Each compartment is assumed to share an identical response function, so the diffusion‐weighted signals are dependent only on the orientations of the fiber populations in the voxel and on data noise. We further assume that there is no exchange of water molecules between fiber populations, and that each SFP can be represented by a signal the average difference between the estimated and simulated number of FOD peaks;the angular deviations between the estimated FOD peak orientation and the simulated fiber orientation;the estimated separation angles in case of multiple fiber populations;the FOD peak magnitudes in case of SFPs;the percentage difference of the estimated AFD with respect to the AFD with the reference response function.Among the SD frameworks, the CSD approach is implemented in several software packages, including MRtrix,The AFD computation was performed as the integral of the FOD magnitudes assigned to each peak, which in the literature is commonly referred to as “lobe.” The calculation of the AFD is similar to what was used in a previous study,b‐value equal to 3000s/mm2, a set of 60 gradient directions,S0=1. Rician noise (1000 noise instances) was added to the diffusion‐weighted signals to simulate SNR (with respect to S0) levels of [50 40 30 20 15 10]. In the first simulation, a single‐fiber configuration was generated with the main diffusion direction along the z‐axis, setting α=1.2×10−3mm2/s and K=0.5 ). In the second simulation, a second fiber population was rotated around the y‐axis and combined with the SFP generated in the first simulation to achieve a separation angle ω. Here, we simulated crossing fiber populations with separation angles ω = . To further explore the impact of inaccurate response functions with respect to the diffusion weighting, a set of multishell diffusion MRI signals was also simulated based on the same HCP dataset gradients, including three diffusion weightings of b = 1000 s/mm2, b = 2000 s/mm2 and b = 3000 s/mm2.We simulated different fiber configurations with a predefined 0.6×10−3mm2/s to1.8×10−3mm2/s with steps of 0.1×10−3mm2/s, while keeping K constant  while keeping α fixed as 1.2 ×10−3mm2/s were tested.The 2D projection of two sets of response functions was simulated to achieve (1) different shape but the same scaling factors, by increasing α from t Figure ; and (2)t Figure . In this◦) to make sure the correct peaks were being extracted for further evaluations.We clustered the peak directions to make sure that we are always comparing the angular deviations between the simulated fiber orientation and the FOD peak most closely aligned to that orientation. Like in other studiesb‐value of 3000s/mm2 in addition to 18 nondiffusion‐weighted images, and with an isotropic spatial resolution of 1.25×1.25×1.25 mm3. We performed CSD‐based tractography in ExploreDTI with a step size of 1 mm, an FOD threshold of 0.1, an angular threshold of 30◦, and seeding points per 2 mm x 2 mm x 2 mm across the whole brain. All the tracts were constructed with deterministic fiber tracking to facilitate data interpretation.Diffusion‐weighted MRI data of a single HCP subject were further used to illustrate the effects of ill‐defined response functions on voxel‐wise FOD characteristics and brain tractography. In summary, diffusion‐weighted images were acquired along 90 diffusion gradient directions with a [0.1−0.3×10−3mm2/s], while the scaling factor K was modified by +/– [0.1 − 0.2] to simulate the response function in the case of pathology. The FOD characteristics estimated from the reference response function were set as the baseline values for comparison.The reference response function for the in vivo dataset was represented by the diffusion tensor fit to the response function, as estimated with the recursive calibration approach.In analogy with the simulations, we computed the voxel‐wise difference in number of estimated FOD peaks, the angular deviations of the main orientation, and the percentage difference in AFD of the dominant fiber orientation, for all the estimated FODs. The comparisons of number of FOD peaks were computed for the whole brain, whereas the comparisons of angular deviation and AFD were only computed for voxels with FA > 0.2.Individual white matter fiber bundles were extracted by using the regions of interest as suggested by Wakana.Figure α and the radial diffusivity β of the response function on the FOD characteristics for multishell simulations. The SNR level clearly affects the estimated FOD characteristics, leading to higher angular uncertainty in correspondence of lower SNR. The angular deviations increase slightly at low SNR when the shape factor of the response functions is bigger than 1.5×10−3 mm2/s, but does not affected by the radial diffusivity β. Overall, the deviations are smaller than those from single‐shell estimation.Figure ◦)  Figure . At the −3 mm2/s for the simulated separation angles of 55˚, 50˚, and 45˚, respectively. The AFD values converge to the AFD of the other separation angles as the shape factor increases. As shown in the angular characteristic results  with decreased shape factors can be a confounding factor in intersubject comparisons of AFD studies, which will be discussed further. At SNR 10, the AFD differences are more related to noise than to the shape of the response function for smaller separation angles (below 60˚). As for the second peak  showed higher peak number differences than regions with white and gray matter.In this section, we present the effect of changing the shape factors of the response function on FOD characteristics for an axial slice of the HCP dataset. The difference in number of FOD peaks per voxel is shown in Figure ˚. Increasing the magnitude of Δα resulted in larger angular deviations.The left panel of Figure α of the response function. Figure ×10−3 to 0.3 ×10−3mm2/s, the highest AFD differences (around 6–8%) were observed in areas with an SFP, such as the corpus callosum. Larger changes of the magnitude of the shape factor α make the AFD difference more heterogeneous across the brain.The left column of Figure Figure Figure α) factors, scale (K) factors, and the FA of the response functions estimated from single‐fiber voxels of several fiber bundles and SFPs of an HCP subject, along with the percentage differences  compared to those calculated from the recursive calibrated response functions from the single fibers across the brain. The forceps show higher shape, scale factors, and FA, while the inferior fronto‐occipital fasciculus, inferior longitudinal fasciculus, and the superior longitudinal fasciculus show lower shape, scale factors, and FA as compared to SFPs. Other fiber bundles also show differences in the shape and scale factors when comparing to the values of SFPs.Table ˚) and at low SNR levels. Further, AFD estimation can be influenced by the choice of response function.In this work, we investigated the effect of changing response function properties on the FOD characteristics using numerical simulations and data from the human connectome project. We have shown how miscalibration of the response function, as defined by adjusting the shape factors, can introduce a bias in the orientation and magnitude of fiber population peaks. Our findings demonstrate that CSD is prone to produce spurious FOD peaks in the presence of miscalibrated response functions, especially in combination with data with insufficient SNR levels. The occurrence of such spurious peaks, however, mainly happens in CSF and cortical areas, thus the fiber pathway reconstruction was only subtly affected. Overall, in agreement with former studies, spurious peaks are introduced due to overestimating the shape factor of the response function, while underestimating the shape factor will result in lower angular resolution of the FOD lobes.In Figure The response function represents the expected signal profile in voxels containing a single white matter fiber orientation, which is supposed to be comparable among healthy subjects. In CSD implementations, such as MRtrix and ExploreDTI, the response function is estimated per subject to capture individual‐specific properties of the white matter structure in single subject studies, in particular for the purpose of fiber tractography. In group studies on voxel‐wise diffusion metrics, however, how to define or choose the response function requires further thought. Specifically, when measuring the response function from pathology regions or brains, whether a response function should be estimated from healthy tissues or pathological tissues need to be considered. In pathological structures, the response function may have lower scaling and shape factors due to, for example, loss of axons. When a healthy tissue response is used, the AFD will be proportionally smaller and reflects the lower axon density. In this case, the response function measured from healthy tissues can be used as the measuring unit for the deconvolution approaches to identify FOD characteristics.The intersubject response function deviations can have several reasons, including but not limited to axon density, axial diameter, membrane permeability, and myelination.In case of regional pathology, the response function should be derived from global estimation or healthy tissues, instead of from the region itself. The response function then does not vary spatially to reflect local tissue properties, but serves as the measure unit for comparing, for example, AFD. The degraded AFD in presence of a global response function reflects the axon degeneration caused by pathology. As we mentioned in the introduction, this raised concern on whether it is optimal as well for tractography and whether it affects the accuracy of local FOD estimation. Since pathology may cause a reduction in the shape factor in the measured diffusion signal, it could be argued that the healthy tissue response function would have a shape factor that is too high for the estimation of the FOD in this region. A response function with a larger shape factor could result in more spurious peaks on the one hand, but also preserve or increase angular resolution on the other hand. This means the tractography performance would be preserved, as also shown in the in vivo tractography illustrations in Figures For clinical applications which aim at detecting regional pathology within every single subject, a global response function can be used in the FOD estimation. As such, the same measuring unit, that is, the response function is used, and the regional tissue characteristic differences of the shape and scaling factors would be reflected in the corresponding deviations in the FOD metrics.˚), the average angular deviations and their variance increase rapidly with lower shape factors of the response function. Higher shape factors of the response function result in smaller bias in the computation of the FOD peak orientations than the underestimation of the shape factor  response, and will result in a decrease in the mean FOD. Applying the current formulations of the shape and scaling factor does not allow clean separations of the impact of shape and scaling effects on AFD. A more advanced formulation of the shape factor will benefit further studies to cleanly separate its impacts on FODs from the scaling factor effects.The reference value of the shape and scaling factor of the simulated diffusion‐weighted signals matches with the values in the corpus callosum as reported before. However, recent studiesIn this study, we showed tractography results of an HCP subject using the tensor‐fit to the recursively calibrated response function and modified response functions. In group studies between healthy subjects and patients with neural degradation diseases , applying the group response function in the FOD estimation is suggested, as otherwise the FOD characteristic changes could be absorbed into the alterations of response functions, leading to failures of discovering FOD metrics changes.Overall, the study demonstrates with numerical simulations and in vivo HCP data that decreasing the shape factor of the response function can cause large angular deviations of the FOD peak orientations in crossing fibers. Sharper response functions are responsible for introducing spurious peaks, which can also confound subsequent tractography results. Extremely low shape factors of the response function can cause significant angular deviations and may complicate the interpretation in studies involving pathology. In addition, although individual angular deviations of FOD peak orientations are small for single voxels at most separation angles, the adverse effect can accumulate for brain tractography. Since smaller separation angles are more sensitive to changes of response function shape factors, future work of intersubject AFD and pathological groups should be aware of this possible confounding factor when investigating brain structures with crossing fiber configurations.


This paper presents original measurement methodology and detection approach to determine the influence of the magnetic field on the partial discharge (PD) dynamics. The application areas refer to insulation systems of both grid and industrial network devices and emerging segments such as high-speed rail, electric vehicles or more electric aircrafts. Conventionally PD measurements are executed only in electric field, however the interaction of magnetic and electric fields influences the dynamics of PDs. The measurement technique allowed to detect quantitatively the effect of magnetic fields on PDs in two representative arrangements: in gaseous void in dielectric material and in corona point-plane setup. Measurements in both configurations have revealed amplification of PDs intensity. The quantitative comparison of PDs evolution in the magnetic field is a novel aspect shown in this paper. Combination of phase resolved images and time-sequence intensity diagrams obtained at magnetic field switching allowed to visualize and determine quantitatively this impact. This effect is attributed to the extension of the charged particle trajectory and the amplification of the electron energy due to acceleration. Thus, the investigated impact of a magnetic field can be perceived as an additional element that influences the PD dynamics. The experimental observations in this work were focused on tracing a streamer’s trajectory in the presence of a magnetic field. It was shown that the drift motion in crossed electric and magnetic fields is influenced by the Hall angle. Without scattering, electrons move in cycloidal orbits in a direction perpendicular to the electric and magnetic fields. At each scattering event, the electron momentum changes, and a new cycloidal path is taken. The path connecting successive scattering events is forming a trajectory. Imaging observations have shown that the discharge is clearly deflected sideways with an increasing angle at an increasing magnetic field. At higher pressures the streamers branch more often and the velocity of the streamer propagation decreases with pressure. The effects of an alternating magnetic field on a point-plane corona that is measured in an ultra-high frequency (UHF) band were reported in2. It was shown that the power spectral density in the corona is reduced in the UHF band of 650–800 MHz in the presence of a magnetic field (250–300 Gauss), for gaps ranging from 15 to 40 mm. The study of a magnetic field on DC corona discharges in a low vacuum was shown in3. It was demonstrated that the effect of a magnetic field on a discharge current was most significant with negative corona discharges rather than with positive ones. A magnetically enhanced negative corona that results from field penetration on an ionization region was described in4. It was noticed that the relative increase of the discharge current was much larger when the permanent magnets were located near the discharge electrode than near the collecting electrode. The corona inception and breakdown voltage were greatly influenced by the presence of a magnetic field as observed in5. It was found that the corona onset voltage and the breakdown voltage decreased with increasing the crossed magnetic field. The influence of a DC magnetic field on PD phase-resolved patterns in a corona cone-plane configuration was discussed in6. It has been shown that the magnitude and phase distributions of partial discharge patterns are affected by a perpendicular magnetic field. The influence of an external magnetic field (128 mT) on the statistical parameters of partial discharges in voids was analyzed in7. It was found that, although visible differences appear in the PD pattern with and without an applied magnetic field; these cannot be attributed solely to the effects of the Lorenz force. Because PD patterns are state-of-the-art in the diagnostics of high voltage insulation of power equipment today17, the influence of other factors such as background magnetic fields, similarly to voltage harmonics18 are essential for the proper interpretation of any measurement results. The influence of the longitudinal magnetic field on the parameters of the plasma electron source and geometry optimization was shown in19. The magnetic field influenced the electrical breakdown characteristics in gas. The investigations that were performed in argon and nitrogen in both the crossed and parallel fields demonstrated the dependence of the electron yield in the magnetic field20.The electrical insulation of grid and industrial networks devices as well as emerging segments such as high-speed rail, electric vehicles or more electric aircraft is exposed to higher and higher stresses due to increased voltage levels in those applications. The focus of this paper is on original measurement methodology and detection approach to determine the influence of the magnetic field on the partial discharge (PD) dynamics. This is a new research topic, since conventionally PD measurements are executed only in electric field, however the interaction of magnetic and electric fields may influence their behaviour. The high-voltage electric power equipment is constantly exposed to both electric and magnetic fields. It is important to notice that the insulation systems of various grid, substation, rail and industrial network devices such as power transformers, cables, gas-insulated systems and lines, converters, motors, and generators are also exposed to the magnetic fields that are caused by the current flow in conductors; this refers to both AC and DC cases. Since the reliability of electrical power equipment at high- and medium-voltage levels is critical for energy transfers and conversions, advanced design techniques and diagnostic methodologies are being developed. One of the key indicators of high-voltage (HV) insulation quality today is based on the measurement of partial discharges. There are various forms of discharges that are related to the defects that can be found inside or on the surfaces of electrical insulation. In this context, one can typically distinguish internal discharges in tiny air inclusions called voids along with surface discharges or corona discharges. This partial discharge evolution is related to the streamer stages such as inception, channel formation, and development. Streamers are usually interpreted as microchannels of ionized gas and propagate along electric field lines. In the presence of a magnetic field that is superimposed on an electric one, the streamer trajectory is altered due to the additional Lorentz force acting on the charged particles; this leads to a complex circular motion. The propagation of streamers in a very high magnetic field (10 T) was shown in21. The measurements revealed enhanced PD intensity in the presence of a magnetic field that can be observed in a supply voltage frequency range of 20–400 Hz . The PD intensity was amplified in the above range at magnetic field induction 80 mT, even up to 50%. In power transformers, stray leakage magnetic fields of up to 700 mT may be present22; these could even be much higher during short-circuit currents, which would lead to winding deformations23. The effects of a magnetic field that is created by a load current on the partial discharge parameters in power cables and on the breakdown characteristics of impregnated paper insulation were shown in24. It was reported that the presence of an alternating magnetic field impacts the probability of electrical insulation breakdown and the Weibull distribution parameters. The morphology of the breakdown region is shown to be different under electric and electromagnetic field influence with scanning electron microscopy and energy dispersive spectroscopy. It was demonstrated that the performance of ozone production based on plasma reactors was improved when introducing a 0.4 T magnetic field in an interelectrode gap of 15 mm25, which led to higher discharge intensity. The production of magnetic field-enhanced DC corona ozone results in an extended current–voltage range and the observed stabilization of the discharges26. Similarly, enhancing cathode glow discharge intensity by a 650 mT magnetic field was observed in27, since the magnetic field was expected to increase the electron energy and promote electron collisional ionization. Electrical treeing in cross-linked polyethylene (XLPE) cable insulation subjected to a perpendicular magnetic field within a range of 350–550 mT was analyzed in28. It was shown that the tree morphology varied from the branch to bush types. The influence of a high gradient magnetic field on tree growth in epoxy resin was investigated in29. According to observations, the electrical tree inception and growth was accelerated in a gradient magnetic field. This result was explained by the rise in the conductivity of epoxy resin and dielectric loss tangents, as well as the drop in relative permittivity of the dielectric material subjected to a high magnetic field (up to 3 T). Simultaneously, it was shown that a strong magnetic field may generate more traps with shallower energy levels, decreasing the deep traps. As a consequence, the tree lengths were significantly longer after being subjected to a magnetic field than they were without a magnetic field30. According to observations magnetic field fostered the development of electrical trees at cryogenic temperatures; moreover, the effect on the length was greater than it was on the width31. Tree growth can also be impacted by a magnetic field while subjected to a repetitive train of pulses; this was demonstrated with silicone rubber in32. The effects of a magnetic field (0.4 ÷ 1.2 T) on the surface flashover of polyimide film for superconducting magnet insulation was described in33. The experimental results showed that a magnetic field drifting into a surface may block secondary electron emission, leading to an increase in the flashover voltage. It was also reported that the breakdown voltage depended on the inclination angle between the magnetic field vector and the surface of the dielectric material34. The investigations of magnetic field impact on corona discharges in oil were presented in35 using fluorescent and UHF detection. It was observed that the dominant frequency of the UHF signal obtained under AC voltage shifted towards a lower frequency (0.6 GHz) under the influence of the magnetic field (85 mT).A magnetic field is generated by the current that flows through the conductors of transformers, power cables, gas-insulated systems, converters, etc. The globally observed trend toward electrically supplied devices is common also in the transportation segment. The influence of magnetic fields on PD in insulation systems of transportation power devices is presented inThis paper is focused on the original measurement approach, detection and quantitative visualization of the impact of a magnetic field on the PD dynamics in air. The presented results are based on both simulations and measurements carried out in dedicated setup. The quantitative comparison of PDs evolution in the magnetic field is a novel aspect shown in this paper. Important difference is, that previous published works have been performed in strong magnetic field. In the experiments presented in this paper, a quite weak magnetic field was set in order to detect PD behavior at the bottom-line field level in power devices. Actually, two distinctive cases were considered: the first one refers to PDs in gaseous (air) voids, and the second to corona discharges.36. The path may also be influenced by dielectric surfaces39 or barriers. Since HV insulation is exposed to magnetic fields in all current-carrying devices such as cables and power transformers, the electrical exposure refers to the high voltage; however, the magnetic field is related to the load. In this way, partial discharge behavior is potentially modulated by the current flow. The magnetic field impacts the pathway and dynamics of the particles in the gas, thus forming the discharge trajectory. The visualization of streamer propagation in crossed magnetic B and electric fields E is presented in Fig. B and E fields, the initial direction of charged particle velocity vector v impacts the drift propagation. Depending on the initial particle velocity, this can assume various shapes .The theoretical part about discharges and electron behavior in magnetic field is highlighted for general information because conventionally in the PD discipline usually only the electric field is considered. Thus, such an introduction will also underline the magnetic aspects. The partial discharges that appear in a strong electric field are described by the inception and propagation of charge carriers and are detected as current pulses. These streamers usually propagate along the electric field linesB and E) that are affected by Lorentz force FL:q is the particle charge, m – the particle mass, and v – the particle velocity.The focus of this paper is at this stage on the charge trajectory in air under a magnetic field, not taking into account neither collisions in gas nor the bulk and surface effects in the dielectric material. Thus, the theoretical part and the simulations shown in the next paragraph refer to the behavior of particles in a vacuum, without collisions. The charges move in the superimposed magnetic and electric fields . The resulting Larmor frequency fL for the electron and proton at 100 mT yields 2.72 GHz and 4.26 MHz, respectively40. The latter is utilized in nuclear magnetic resonance (NMR).Simultaneously, the magnetic moment of the particle presses around the external magnetic field vector with Larmor frequency τ that is defined by1 into account):τ can be expressed as follows:The drift equation for the particles in the crossed electric and magnetic fields is as follows  or nonelastic (in case of atom ionization by collision)1. It is assumed that the pathway that connects consecutive ionization steps in the crossed E and B fields determines the streamer path.This denotes the FE and FB) that acted on the electron was performed:E is the electric field strength, B—induction of the magnetic field, and ve—electron velocity.For assessing the influence of the magnetic field on the charge movement in the electric field, a relative comparison of the electric and magnetic forces (E = 10 kV/cm at pressure p = 1013 hPa and at room temperature T = 293 K is within the ranges of ve = 2.9 × 106 cm/s)41, ve = 6 × 106 cm/s36, or according to the equation in dry air42:ve is in [cm/s], E in [V/cm], p in [Pa], and the electron velocity is equal to ve = 8.3 × 106 cm/s. For the above three electron drift velocities, at induction of magnetic field equal to B = 80 mT, ratio FE/FB yields 448, 216, and 156, respectively, according to Eq.  controlled the electric field and the magnetic field oriented perpendicularly remained constant. While analyzing the trajectories of individual discharges, both fields can be treated as constant since the streamer propagation time is within a range of nanoseconds.43. The simulation sequence consists of two consecutive elements: in the first step, the magnetic and electric fields are computed. Afterwards, charge particle tracing is carried out in the subsequent step, in the superimposed magnetic and electric fields reflecting the motion equation and resulting forces. The obtained trajectories can follow cycloidal or helical pathways in both fields. Therefore 3D simulations are suggested, particularly when non-homogeneity or gradients along the axes in electric and magnetic fields are also present. View of the 3D configuration of simulation domain (cross-section) with the variable air gap that was used for the simulation is presented in Fig. a from the plane radial ground electrode.The simulations were used to investigate the trajectories of the particles in the cross-coupled magnetic and electric fields. The intension of the simulation was to study a hypothetical pathway subjected to the superposition of both magnetic and electric forces, without taking into account interactions of particles such as collisions. In that sense, the theoretical part and simulations shown in this paragraph refer in fact to propagation similar to vacuum conditions. For collisions in air under normal pressure, the electron length path is very short, and the whole mechanism will differ. However, the intension was in a first step to visualize the effect of electric and magnetic field interplay, mimicking the trajectory, which is, in fact related to vacuum. In reality, the discharge is moving along the electric field lines due to the ongoing ionization process; thus, the key point was to investigate the trajectory due to the presence of the magnetic field. It is in fact a channel consisting of electrons and ions, which will be impacted in a more macroscopic view by a superimposed magnetic field. In that sense, the simulation has a more qualitative character to highlight this mechanism. In order to interpret the potential root cause of the elevated number of partial discharges in a magnetic field, a simulation of the corona discharge traces in the point-plane configuration was performed. Because the individual propagation time of a discharge is within nanoseconds, in the simulations the DC condition was taken, reflecting an instantaneous slot on the sinusoidal waveform. The motion Eq.  (the Lora = 20 mm and a = 40 mm between the HV electrode and the ground). Comparisons of the trajectories for both of the interelectrode distances at HV voltage of U = − 10 kV are presented in Fig. B = 40 mT and B = 80 mT. Without presence of the magnetic field   were taken in the simulations. The HV tip was used as a particle beam, releasing 1000 particles from a beam source in a simulation sequence. In the presented examples, at this stage of simulations, the electrons were used in the particle-tracing comparison. As an initial condition, the mean kinetic energy of 5 keV was defined with Gaussian standard deviation σ being equal to 0.1 eV. The trajectory of the particle was rendered as a tube in the graphical visualization. The simulations were executed for two values of gap distances  were used in the tests. The electric permeability εr of the PE material was equal to 2.2. The HV and ground electrodes had a diameter of 40 mm are were made of polished aluminum. In order to avoid surface discharges, the whole setup with a sample was immersed in oil.The geometry of the specimen that contained the void is presented in Fig. r = 60 μm. The PE dielectric barrier with dimensions of 60 × 60 mm was placed on the ground electrode. Interelectrode gap a was changed within a range of 20 to 60 mm. The HV sinusoidal waveform was delivered from an amplifier (model Trek 20/20B) that was controlled by a function generator (Tektronix Model AFG 3011). Limiting resistor Z was placed in the high-voltage path at the output of the HV source. For closing the high-frequency partial discharge loop, coupling capacitor Cc was placed in a parallel branch of the specimen. The PD were acquired in the wideband phase-resolved mode (PRPD) using an ICM-acquisition system by Power Diagnostix. The unit was attached to a control computer by means of a GPIB interface. The detection of the PDs was performed using a wideband current transformer CT that was terminated at 50 Ω. The presented experiments were executed at room temperature (21 °C) with a humidity level of 24% and an atmospheric pressure of ca. 0.1 MPa.The corona point-plane geometry is shown in Fig. The interesting observation that is reported in this paper refers to the modulation; i.e., the amplification or attenuation of PD intensity by a superimposed magnetic field. In order to investigate the influence of a magnetic field on partial discharge dynamics, two types of experiments were conducted: first—in a gaseous (air) void; and second—in a point-plane corona configuration in air with a dielectric barrier. The discharge dynamics was indicated and visualized in the performed experiments by the number of discharges that were recorded within a predefined time interval and is referred to as intensity in this paper. The experiments were performed in a static magnetic field with an induction of 80 mT. This relatively low field was applied in order to detect PD behavior in a field range that can possibly occur in everyday power devices. Regardless, this field is three orders of magnitude higher than Earth’s magnetic field .a1 = 250 μm, and a2 = 1 mm). The PD inception voltages for these samples were 8 and 7.6 kV, respectively. With the presence of magnetic field both PD inception voltages were slightly lower, yielding 7.5 and 7.2 kV. The inception voltages are quite similar, and this effect refers to the breakdown voltage in the air at small distances. Namely, the common value of electric field withstand for few millimeters interspaced cavity at normal pressure is 3 kV/mm, whereas for submillimeter distance it goes up to 5 kV/mm, and further to 9 kV/mm for tiny voids 0.01 mm thick10. The PRPD patterns that were recorded at 10 kV for the specimen with thickness a1 are shown in Fig. a2 in Fig. 10.The partial discharge measurements were performed in the experimental arrangement that is shown in Fig. a2 = 1 mm) in the PE, the PD intensity, denoted by number of discharges N, rapidly grew after switching on a magnetic field with an induction of 80 mT  from 745 (the average of both polarities) at the steady state to 785 (just after the magnetic field transition). For the thicker void  PD pulses versus the applied voltages within a range of 8 to 20 kV for both the magnetic field-free and magnetic field-present measurements is shown in Fig. The number of PD pulses of both polarities grew for a thinner inclusion , there is a certain critical inclusion geometry where this effect is substantial. In the investigated void geometry and at a magnetic field induction of 80 mT, this effect was not detected below the thickness of ca. 100 μm (even the attenuation of the PD number was noticed). Thus, comparing these cases , a significant influence was observed . The effect of a magnetic field on the PDs was more predominant for the thicker void. The non-uniformity of the magnetic field may have additionally influenced the charge trajectory locally. The number of collisions between the electrons, ions, and gas molecules was enhanced by a magnetic field along the elongated trajectory, including amplification of electron energy due to acceleration in the magnetic field; these were the root causes of the investigated phenomena.45; the measurement setup is shown in Fig. a between the tip of the point electrode and the ground . A constant magnetic field with induction B equal to 80 mT was applied in the direction that was perpendicular to the point-plane arrangement . The PD patterns that were recorded for above-mentioned three interelectrode distances and two extreme voltage values (9 and 16 kV) are shown in Fig. The second set of experiments was performed in a point-plane corona configuration in air with a dielectric barrier (PE) placed on the ground electrode−. The last transition was to turn the magnetic field off to the stage (IV), where the PD level corresponds to the initial value. The influence of the magnetic field on the PD dynamics is shown in Fig. a of the HV tip from the ground; within each pair, there are traces that reflect the B = off and B = on stages. Number of discharges N- corresponds to acquisition within 60 s. The plot reveals the linear relationship of the number of corona discharges with the rising voltages (from inception to certain stage prior saturation). The most important observation is that, in all cases, the PD intensity was amplified with the presence of a magnetic field. At corona inception level U0 (U0−PD inception voltage), this increase was smaller (reaching the broader span between the lines at 1.2U0). It should be noticed that the observed PD inception voltage with the presence of magnetic field was lower by about 8% comparing to B = off stage. The lilac (9 kV) and red (16 kV) dots indicate the correspondence to the PRPD patterns in Fig. Prior to the measurements, the test sequence was executed to make sure that the detected signal variation came from the applied magnetic field. A diagram of the switching sequence is shown in Fig. The markers of the time sequence profiles that are shown in Fig. − was attenuated. Unlike for a = 40 mm, the voltage rise from 9 to 14 kV was associated with the strong dynamic growth of ΔN− – from 260 to 1620, respectively). The above examples indicate that introducing a magnetic field leads to an amplification of the discharge intensity and an increase in the number of streamer channels. In the case of the corona, the enhancements refer to both the ionization zone and drift region. This effect can be confirmed by simulations presented in section “a = 20 mm and a = 40 mm indicates elongation of the electron path, thus probability of discharge inception. Simultaneously, the residence and propagation time tp in those two cases at B = 40 mT is extended from 0.5 to 1.1 ns.The time sequence of the PD-intensity profiles at three voltage levels  as well as two interelectrode distances (20 and 40 mm) are illustrated in Fig. 1, results in an increase in the number of discharges, as measured in the presented experiment, due to the higher probability of discharge inception on a longer path. The perpendicular magnetic component is enhancing space charge concentration in the whole inter-electrode region, enlarging the possible ionization volume , thus increasing the collision probability with ions and gas molecules. It may also result in an increase in the number of streamer channels, hence a higher PD number. The longer trajectory also means a longer residence time by charges in the interelectrode space, especially electrons that cause successive ionization events. This effect will impact also magnitude of the discharge. In a more macroscopic view, a propagating streamer channel consisting of electrons and ions will be impacted by a superimposed magnetic field. In future research, should be analyzed in addition to effects related to charge transport in the air, interfacial effects associated with the interactions on the PE surface, including surface emission and charge accumulation.The focus of the paper was to report the magnetic field modulated dynamics of partial discharges. Understanding the physical mechanism of the influence of the magnetic field on PD is a complex topic requiring further research. At this stage, some hypotheses can be put forward, which may explain the influence of the number of PD pulses, affecting also the PD magnitude. The higher number of PD pulses in the presence of magnetic field may be attributed to the lower inception voltage, which was observed in both cases, i.e. in the experiments with voids and corona. In addition to an electric field, the magnetic field component gives rise to an additional Lorentz force on charged particles. This force acting on free electrons in a crossed E × B field results in stronger acceleration compared to a drift only in an electric field, which will impact the energy of free electrons and enhance the ionizations of gas molecules. In this way, the magnetic field acts on the focused ionization zone, lowering the PD inception voltage and resulting in a higher number of discharges compared to B = off stage. The stronger acceleration impacts the number of collisions between the free electrons and the gas molecules, as well as the mean energy of the free electrons. Another hypothesis with respect to PD dynamics may be related to the fact that, due to different polarities, electron and positive ions will be deflected in opposite directions, extending the free electron path between collisions, thus causing more high energy electrons, leading to an increased ionization rate. In this scenario, deflection of positive ions will result in promoted free electron path, decreasing local recombination rate and thus increasing the probability of collision event. This effect will result in a higher number of PDs as well. The deflected trajectory of the discharge path under crossed magnetic and electric fields, visualized by imaging inThis article presents original measurement methodology and detection approach to determine the influence of the magnetic field on the PD dynamics. The measurement were executed in the original setup which allowed for sensitive detection in the presence of weak magnetic field, unlike conventional PD measurement are carried out only in an electric field. The applied measurement technique allowed to detect the effect of magnetic fields on PDs in void and in corona mode. It was demonstrated that the interaction of electric and magnetic fields influences the dynamics of partial discharges in both configurations. In the acquisition approach time switching technique of magnetic field presence was synchronized with the PD detection. Combination of phase resolved images and time-sequence intensity diagrams allowed to visualize and determine quantitatively the impact of magnetic field on PDs.It was shown in simulations, that the crossed electric and magnetic fields influenced the charged particle path, i.e. the elongations and turbulences of the electron beam trajectory. Due to the deflection that was caused by the effective Lorentz force, a longer pathway also led to prolonged residence time benchmarking while only being exposed to an electric field. At certain ratios of magnetic and electric fields, the presence of a magnetic field may lead to a focused and localized discharge spot, not a dispersed one as can be found in a field-free case. In this way, a magnetic field elongates the charge trajectories  as well as enhances the energy; this is due to the acceleration in the combined fields. This can increase the probability of ionization, thus effectively increasing the discharge intensity; this was also confirmed by the measurements on both voids in the dielectric and corona. On the other hand, the twisting of a charge pathway may attenuate or even stop PD action. Such effects were observed for very tiny voids. It was shown that the impact of a magnetic field also depends on void thickness in the case of dielectric embedded inclusion . In the case of the gaseous inclusion in the dielectric material, there seems to be a certain critical inclusion geometry above which this effect is substantial. For example, the effect was not detected, and the attenuation of the PD number was not even noticed in the investigated void geometry and at magnetic field induction of 80 mT below the thickness of ca. 100 μm. The effect of a magnetic field on PDs was more predominant for the thicker void. Also, the number of discharges quantitatively rose more dynamically while increasing the voltage in the presence of both fields as compared to the reference case with only an electric field. This effect is attributed to the elongation of the charged particle trajectories and the enhancement of the electron energy due to acceleration. The presented study may contribute to measurement methodology, detection technique and the understanding of physical phenomena. It can raise the awareness of PD-intensity modulation that is caused by the presence of magnetic fields in most electric power devices. Thus, the effect of a magnetic field can be perceived as an additional modulation factor that influences PD dynamics.


Hyperbilirubinemia is a common health problem in newborns. Its effects can be different according to the level and duration of the hyperbilirubinemia. The toxic effect of bilirubin on the auditory system can be seen as a sensory neural hearing loss or auditory neuropathy spectrum disorder (ANSD).The purpose of our study was to determine the effects of toxic bilirubin level on the auditory system by using Auditory Brainstem Response audiometry.Rats are used as animal models due to their low cost and easy attainability. Auditory Brainstem Response was used for auditory assessment. In this study, three groups were established: experimental, control and placebo groups.p < 0.05).In the experimental group, which consists of rats with hyperbilirubinemia, sensory neural hearing loss was found bilaterally in 4 rats (66.67%) and unilaterally in 2 rats (16.67%) and auditory neuropathy spectrum disorder was found unilaterally in 1 rat (8.33%). Auditory Brainstem Response thresholds were significantly elevated compared to control and placebo groups (Hyperbilirubinemia of newborn rats may result both in sensory neural hearing loss and auditory neuropathy spectrum disorder. Hyperbilirubinemia is a common health problem of newborns. Newborn hyperbilirubinemia has been accepted as one of the main risk factors in infants’ hearing loss since the 1900s.SNHL results from pathology in the cochlea, 8th nerve, brain stem or cortex level. Although 50% of SNHL in children is genetic, it can also develop depending on pathologies in the prenatal, natal, or postnatal periods .ANSD is an issue that has many unknown aspects and it is widely studied. In some cases of ANSD, while only the inner hair cells in the inner ear are affected, in some other cases only the central auditory pathway is affected. Among the ANSD risk factors are hyperbilirubinemia, premature birth, and genetic, perinatal mechanical ventilation. ANSD related to hyperbilirubinemia is seen in 2.7% of newborns with hyperbilirubinemia.Hyperbilirubinemia may have different pathological effects on the ABR pattern of affected individuals. In newborns with hyperbilirubinemia, the ABR pattern can either go back to normal or become even more pathological after blood bilirubin levels are brought to normal with treatment.9The purpose of our study is to determine the effects of toxic bilirubin level on the auditory system by using Auditory Brainstem Response audiometry.The study has been conducted in the local Experimental Animals Research and Application Center of the Faculty of Medicine. The approval of the ethical board has been taken .Three groups have been included in the study, as experiment, placebo and control groups and 6 newborn rats have been used for each group. The number of rats in each group was restricted by the ethics committee. The ear examination of all rats has been performed with endoscopes by an otorhinolaryngologist.The experiment group consisted of 6 newborn Wistar Albino male rats with hyperbilirubinemia, with weights between 18 and 20 g (average: 18.33 g). A Rat Hyperbilirubinemia Model has been created for the experiment group.The method for establishing hyperbilirubinemia was similar to methods previously reported.The placebo group consisted of 6 newborn Wistar Albino male rats with weights between 18 and 20 g (average: 18.3 g). As the placebo solution, BSA and 24 mg/mL Krebs-Ringer buffer (pH: 7.5) have been used. The prepared solution has been preserved in +40 °C, in a shaded place. In order to determine whether it has an effect on the hearing system of rats, the solution which has been prepared without bilirubin has been applied in exactly the same dosage which has been applied to the experiment group. The placebo solution has been given in the same procedure applied on the rats in the experiment group and has been subjected to the same processes.The control group consisted of 6 newborn Wistar Albino male rats with weights between 18 and 20 g (average: 19 g). Contrary to the experiment and placebo groups, the rats in the control group have not been given any injections. However, in order to determine their bilirubin levels, coordinated evaluations have been performed with the time slices determined for the experiment and placebo groups and they have been subjected to the same processes.The ABR evaluations of the rats included in the study have been performed with the Bio-Logic Systems Corp.’s Navigator Pro Model (version 2.2.0) device. In the ABR evaluations, 13.00 rate click stimulus, 10 msn analysis time, 1000 sweep in averaging, 100–1500 Hz filtration have been used. Changes in the intensity have been made in accordance with the responses achieved in the 70 dB nHL intensity level recordings. In order to determine the CM existence, the condensation (+) rarefaction (−) polarity change has been applied in the same intensity for both ears. For the threshold scan, as it is advised in the click stimulus, it has been continued with rarefaction polarity.Transcutaneous Bilirubinometry (TcB) has been performed with Minolta/Air – Shields Jaundice Meter . TcB measurement has been performed on the back area of the rats. Prior to the measurement, technical maintenance and calibration of the device has been performed. During the measurements, due to the pressure applied by the probe, an acrylic plaque was made to prevent the rats from being damaged.Serum Total Bilirubin levels have been analyzed using readymade kits (Roche) in auto analyzer (Roche/Integra-800) systems. The total bilirubin measurement principle of this kit is the Diazo method based on the measurement of the amount of azobilirubin, which is the result of the reaction of bilirubin and diazotized sulfanilic acid.p < 0.05. The Mann–Whitney U test has been performed to test the significance of pair wise differences using Bonferroni correction to adjust for multiple comparisons (0.05/3 = 0.016). An overall 5% type I error level has been used to infer statistical significance. The correlation coefficient of the relationships between the variables in the groups and statistical significance has been calculated by the Spearman test. An overall 5% type I error level has been used to infer statistical significance.Statistical analysis has been realized in SPSS for Windows Version 16.0 packaged software. The TcB results used to determine the bilirubin levels in the groups have been compared with the STBL, ABR findings for the hearing evaluation differences in the groups, hasn’t been normally distributed the Kruskal–Wallis Variance analysis has been applied. The level of significance has been taken as p > 0.05), the TcB results performed 24 h after the 1st and 2nd bilirubin injections show that there is a statistically higher level of bilirubin (p < 0.05) in the rats in the experiment groups compared to the rats in the placebo and control groups. When the STBL in blood is compared between the groups, it has been observed that it is higher in statistically significant terms in the experiment groups in comparison to the placebo and control groups. It has been observed that there is a statistically significant positive and strong relationship between the TcB value prior to euthanasia and the STBL value in the experiment, placebo and control groups.While the comparison of the groups in terms of the TcB results  prior top > 0.05), left ear ABR threshold shows a statistically significant difference between groups (p < 0.05). This difference is a result of the fact that the left ear threshold intensity of the rats in the experiment groups is higher compared to the other two groups (p < 0.016)  , Table 2In the evaluation of the CM existence in the ABR pattern achieved from the groups, four aspects have been noteworthy. CM findings have been categorized by taking these observed aspects as a basis. In Category 1 , while CHyperbilirubinemia is an important health problem in newborns. The hearing system is also sensitive to bilirubin toxicity. The damages in the central auditory areas have been defined in both animals and humans with hyperbilirubinemia in anatomical and functional terms. However, the physiological effects and neuromechanism of the damages caused by hyperbilirubinemia in the peripheral auditory organs are still a mystery.It has been stated in the literature that ANSD may be observed in 1/3–1/2 of the cases with a high level of hyperbilirubinemia.Bilirubin toxicity is closely related to STBL. While a high correlation is observed between level of bilirubin in humans and SNHL, this correlation decreases in ANSD; although in levels higher than 20 mg/dL the possibility of observing ANSD increases.In the forming of a rat model with hyperbilirubinemia, bilirubin injection is frequently resorted to, due to the easiness of access and application and achieving absorbed neurotoxicity in the circulatory system in a short time.Hai Bo Ye et al.As Wennberg et al.It is stated that the TcB values reach the maximum level 24–48 h after the bilirubin injection in Wistar Albino rats and that these values decrease by time.In newborns, ABR is frequently preferred in the determination of the effect of bilirubin toxicity on the auditory system. ABR, which is used in the evaluation of auditory sensitivity, is preferred in newborns due to its being objective and non-invasive; its reliability being higher compared to other test methods and determination of CM in the identification of ANSD.19In studies conducted on rats with hyperbilirubinemia, while differences such as latency elongation and decrease in amplitude in ABR have been evaluated, threshold evaluation has also been done along with these variables and it has been observed that there are significant increases in the thresholds of their ABR's.In rats, the anatomical settlement in ABR waves differs from the humans. In humans, while the 1st and 2nd waves originate from the 8th nerve and the 3rd wave originates from the CN, it is known that in rats the 1st and 2nd waves originate from the CN and the 3rd wave originates from SOC.In the studies conducted on newborns with hyperbilirubinemia, it has been stated that there has been a spontaneous improvement in about 50% without any interventions in the patterns where ABR has not been achieved and CM has been observed.In the literature, while the difficulty of long term follow-up in animal studies is underlined, it is also noteworthy that the results related to this are not mentioned. In the study, after the 2nd dose injection, we waited for 11 days, until the rats reached adulthood. During this time, it is thought that the potential effects of the hyperbilirubinemia decrease. However, although the effect of hyperbilirubinemia has decreased, as it can be seen from the study as well, due to achieving high intensity ABR thresholds in line with the bilirubin level, this is thought to cause deteriorations in the wave morphology and in being able to achieve ANSD findings and/or ABR.Podwall et al.During the formation of the model, due to the fact that besides the rat type used, the powder bilirubin used was the same in the formation of hyperbilirubinemia, Hansen et al.When it is taken into consideration that the STBL values are not high in the TcB of this group, it gives rise to the thought that the solution is effective on the auditory system as well. This finding, which may be accepted as the weak point of the study, also provides very valuable information in terms of showing understanding of the real effect of hyperbilirubinemia on the auditory system, by studying the effect of the solution to be used in the formation of hyperbilirubinemia in animal models.As in the study hypothesis, the blood bilirubin levels have been allowed to increase by injecting toxic dosages of bilirubin to newborn rats, and it has been observed that hyperbilirubinemia may cause SNHL and/or ANSD. Besides this, it has also been found noteworthy that the effects of hyperbilirubinemia may appear in different patterns in ABR.In our study, by forming rat model for newborns with hyperbilirubinemia through a toxic dose of bilirubin, the effects of level of bilirubin on infants and children under risk, the results of the electrophysiological hearing evaluations and morphological difference have been analyzed.It has been observed that hyperbilirubinemia can increase the ABR threshold in its long term effects and deteriorate wave morphology. It has been taken under consideration that the deterioration of wave morphology in ABR may be connected to the decrease of synchronization formed by the neural damage in the auditory brainstem and the activation of auditory neurons. It has been observed that hyperbilirubinemia may cause ANSD as well as SNHL and CM can be observed without the ABR response, and that in systemic applications not only bilateral but also unilateral settlements may exist.All financial support of the study was provided by the authors.The authors declare no conflicts of interest.


IntroductionWith the advent of revolutionary information technology, most general medical information can be accessed by the community at large. However, the factual nature of information, its understandability, and actionability of diseases like Hemophilia are unknown to the general population. Hence the present study has been envisaged to assess the understandability and actionability of available video information on YouTube about Hemophilia.MethodsA cross-sectional study was performed using the Patient Education Materials Assessment Tool for Audiovisual materials (PEMAT-AV) to assess the understandability and actionability of 50 videos shown by order of relevance utilizing three independent assessors. An online google survey was prepared using the PEMAT questionnaire as a basis and results were recorded and saved as a Microsoft Excel sheet for analysis. Data was analyzed using either Microsoft Excel or an online calculator as the case may be.ResultsA total of 50 short videos on Hemophilia were assessed by three independent assessors using PEMAT. The data so obtained was rechecked by an independent reviewer before data analysis. Three videos were excluded due to non-English language while only two videos out of 50 showed 100% average understandability and actionability. Average understandability and actionability scores range between 34 to 100 percent and 11.1 to 100 percent, respectively. Most videos have higher average understandability than actionability .ConclusionOur study shows there are only a few high-quality short videos available as audio-visual patient education materials on YouTube about Hemophilia. There is a great need to develop content that is beneficial to patients as patient educational material. The advent of the computer and mobile revolution brought with it the high-speed internet at the present at cheap affordable prices for all. This has increased health education information access to the public through websites, self-help groups, discussion groups, patient groups, chat groups, and app groups ,2. HowevYouTube and search engines have become the source of information for patients replacing the medical personnel in this time of the 5th Generation advanced cellular technologies and information age. Before a patient approaches a doctor for treatment, many a time they might have approached search engines and are more knowledgeable than we might perceive in the aspect of disease pathogenesis, and management. Hemophilia is an age-old, mostly congenital disease with a lot of information available on the internet and there is a huge chunk of information pertaining to the disease incidence, clinical features, pathogenesis, and management. However, it is difficult to go through all the existing data. To assess how useful the information is for patients, we performed this study to assess the understandability and actionability of videos available on YouTube regarding Hemophilia in terms of understandability and actionability using the Patient Education Materials Assessment tool-Audio/Visual (PEMAT-A/V) .The YouTube search engine was searched with the keyword “Hemophilia” sorted by relevance with filters with a duration of under 4 minutes on 5th January 2022 and a playlist was created. We assumed the playlist generated by relevance will be the most seen videos in view of its default nature and given the short duration as most people find themselves reluctant to spend more time to watch lengthy videos when trying to learn something.A sample size of 30 was assumed sufficient to maintain the integrity of the study and enough to warrant assertions against the present study findings. Assuming exclusion of some videos due to exclusion criteria (non-English videos), additional 20 videos were included taking the total number of videos to 50. The playlist was created using the first 50 videos assuming that the patients will not have the patience to see a long list of videos. The videos in the English language were included in the study out of the 50 videos, thus eliminating three videos. All 47 videos were checked and scored by three independent assessors who have been trained to score in a questionnaire based on the Patient Education Materials Assessment Tool-Audio Visual (PEMAT-AV) using google forms. All three assessors were from the medical background and can understand the intricacies involved in Hemophilia and were to assess the videos with an empathic view towards patients with not much knowledge of Hemophilia. The videos were assessed over a period of three months, values reviewed, videos rechecked for the correctness of data entered, data reviewed, analyzed over a period of six months in the year 2022 as per fixed timelines assessed during the study design. The present study has not been designed to assess the difference between the length of videos and understandability, actionability of videos but to assess the actionability and understandability of short videos alone.The understandability was to be assessed for content, word choice and style, organization, layout and design, use of visual aids by a 13-point scale. Actionability was directly assessed by the 4-point system. The PEMAT(A/V) system was used in view of its specificity and individual scoring system. A training was provided to three assessors and one reviewer individually. This was followed by the scoring of the 47 videos individually using a google survey sheet for the collection of responses.A total of 141 responses have been recorded with 47 responses from each of the three assessors. The assessors were made to score the responses independently at different locations to eliminate bias. The recorded data has been coded in such a way as to hide the identity of the assessor by giving a code  and to not trace the response to a particular assessor except for the principal investigator. The final data has been reviewed by an independent reviewer to check for completeness of responses and to recheck the correctness of scores. The assessor's and reviewer's names have not been disclosed to either of them. After ascertaining the completion of the sheet, the data was analyzed using Microsoft® Excel for computation of actionability and understandability scores of individual assessors and average scores. The average understandability and actionability scores were to be compared using Wilcoxon signed rank test to identify if there is a difference in the mean between the two groups using an online calculator [The title of the video, creator of content, and the year of upload have been recorded by the assessors Table . The assThe individual PEMAT scores from three assessors for all videos have been analyzed and combinedly ranged from 7.69% to 100% with a median of 77.78% and an inter-quartile range of 48.07% to 100%. The actionability scores similarly ranged between 0% to 100% with a median of 66.67% and an inter-quartile range of 33.33% to 100% Figure . The PEMAverage understandability and actionability scores ranged between 34 to 100 percent and 11.1 to 100 percent respectively as depicted in Figure A Wilcoxon signed rank test was performed to identify the significance of the difference of means between average understandability and actionability using an online calculator and a statistically significant difference was found with a two-sided P value of 0.003 at 0.05 significance levels with a Z value of -2.9743 and W value of 254.YouTube is the second most visited website after Google and the second most visited social media platform and the world’s first website with audio-visual content ,6.Hemophilia is a disease characterized by a congenital or rarely acquired deficiency of coagulation factors, Factors VIII, IX, and/or XI and this leads to spontaneous bleeding or uncontrolled traumatic bleeding due to a defect in the coagulation.The present study has provided sufficient data to suggest that the existing video material on Hemophilia on YouTube is understandable and actionable. Based on the present study, which required 50 videos to be assessed with a final result of only two 100% understandable and actionable videos, it is presumed that at least 25 short videos must be seen to get at least one 100% understandable and 100% actionable video by a patient. In the present study, there are few videos with zero actionability scores which indicates that the video content developers are more into providing information to the patients than providing information as to what to be done next.In the present study, out of 47 videos screened, seven and 13 videos had average understandability and actionability scores of less than 50% respectively. The mean understandability score (70.9%) has just crossed the threshold of the PEMAT score for patient education materials of 70% [No literature could be found that searched the video material on hemophilia to assess understandability and actionability to date. There are certain studies which have assessed understandability and actionability using PEMAT scores but on different diseases like diabetes , cardiovThe present study is limited by the sample size and study design to assess the understandability and actionability of short videos on Hemophilia only. The sample size could not be calculated in view of the paucity of data to use in sample size calculation. However, the present data can be utilized in designing better studies with a larger sample size in the future with more varied objectives.Our study shows there are only a few high-quality short videos available as audio-visual patient education materials on YouTube about Hemophilia. Most of the short videos are understandable but poorly actionable. There is a great need to develop content that is beneficial to patients as patient educational material.


The accumulation of municipal solid waste (MSW) in landfills often becomes a serious pollution source of geological environment and groundwater. The geological environment is the carrier of the landfill, and also the main pollution object of the landfill. The main pollution modes of the landfill site to the surrounding geological environment are purging, flushing, leachate, etc. If the leachate leakage cannot be found and repaired in time, it will cause serious harm to the geological environment and groundwater. The cost of geological environment and groundwater sampling through borehole surveys is high. Therefore, monitoring the seepage path and migration law of leachate is of great significance for determining the pollution range of the landfill site. In this study, by adjusting the grids of different sizes and changing the flow rate of leachate, the monitoring of fluid migration of different types of leachate was strengthened. The results show that the parallel potential monitoring method can quickly reflect the location and number of leachate points and the migration law of leachate. It provides effective reference data for landfill leachate monitoring. Among them, the pollution source caused by rapid urban development has become the main component of garbage leachate, including micro plastics, sludge and heavy metals, which have potential risks to the geological environment and groundwater4. The effective measures to ensure the normal operation of the landfill site are to establish a leachate collection and removal system and observe the impact of leachate on the mechanical properties of concrete8. It is necessary to monitor the leachate to prevent further deterioration of the surrounding environment of the landfill11.The pollution of landfill leachate to surface water and ground water is mainly caused by the fermentation and erosion of rainwater. As one of the important sources of water supply, groundwater should be protected13. The use of water level wells or pressure wells to monitor the falling distance of seepage from vertical and horizontal wells still has disadvantages such as low monitoring efficiency, discrete data and other interference15.Common ways to reduce the concentration of leachate include using vertical and horizontal wells in landfills19. The monitoring study of water injection reservoir further reflects the resistivity variation characteristics of different media layer20. The potential value of waste area is affected by moisture content22. Borehole-to-surface method has a good effect on the identification of the boundary of resistance abnormal body and the monitoring of its migration law24. The location and extension path of landfill gas are located by electrical resistivity tomography (ERT)26. It is found that there is a certain correlation between the resistivity ρ and the volumetric moisture content θ in the experimental test, which is well expressed by Archie's law28. Time-lapse ERT is used to monitor the leachate plume32.Parallel potential monitoring method is an efficient geophysical detection technology. At present, it is widely used in the field of monitoring the distribution and movement of landfill leachate and gas. It is found that detecting the resistivity value of the site can determine the leachate injection plume, positioning depth and transverse extension40. Figure A large number of experiments have been carried out on the monitoring of leachate migration by ERT method, which proves that this method has an obvious effect on monitoring the distribution of landfill leachate 41. In this experiment, a parallel potential monitoring device was used to improve the monitoring of leakage fluid migration. The simulation experiment in the laboratory is carried out in a (100 cm*100 cm*50 cm) plexiglass tank. Sand and clay shall be screened with a 2.36 mm square sieve, watered and compacted with a board to ensure that the soil layer is in close contact with the measuring electrode.Laboratory monitoring of leakage migration process can provide an important basis for field tests. The designed and improved ERT device can better describe the migration range of leakage in soilThe ground wire of high-density electrical method instrument is connected to the electrodes arranged around the bottom of the tank as the power electrode C2, as shown in Fig. The electrode system is used to monitor the background electric field and artificial electric field of the landfill site. In the experiment, the electrode system is laid in the clay layer under the geomembrane. It is composed of detection electrodes distributed in a grid at a certain distance.The electrical signal conversion system adjusts the measurement mode, sampling accuracy, acquisition frequency and other parameters of the electrode in the field according to the instructions of the mainframe, and transmits the collected electrical signal to the mainframe.The mainframe can control the operation of the monitoring system. The possible leachate points and their pollution range are determined by collecting data. The system mainly includes mainframe and its software system, power supply, etc., as shown in Fig. -1 is a typical pollutant in the landfill. No. 2 bottle containing 20 g/L NaCl solution is used to simulate inorganic salt leakage in urban life. No. 3 bottle containing 20 ml/L ethanol solution is used to simulate the leakage liquid containing a large amount of organic matter in municipal solid waste. The characteristics of leachate have been summarized in TablePlace 4 leakage bottles above the tank. No.1 and No.4 bottled water are used to simulate the leakage liquid formed by the direct infiltration of rainwater in slag through geomembrane and as a reference. Because ClBefore the experiment, configure four solutions, close the injection, use an electric meter to check the conductivity of each measuring point. After each measuring point has no open circuit, supply power to the soil layer through the mainframe to measure the background electric field of the soil. Then open the injection, adjust the flow rate, release the solution at a fixed flow rate, record the soil electric field in the process of leakage every half an hour, collect the potential values of each measuring point, process the data through the potentiometry and potential difference method, and form the relevant potential horizontal profile and longitudinal section of the soil.When there are leakage points in the landfill, power is supplied to the landfill, and the current forms a current loop through the geomembrane. If there are n  leakage points in the geomembrane, the power supply current is I, and the artificial electric field will form a leakage electric field at the leakage point, which can be used as a point power supply.When there are n leakage points, I will be shunted. If a leakage point is regarded as a finite surface, the current intensity I as:Generally, the power supply current field of landfill site will be affected by the formation medium structure. It is assumed that the formation medium structure is composed of three layers, each layer has uniform properties and stable conductivity, and the layers from top to bottom are: landfill layer, with resistivity of ρ1. The saturated leakage liquid layer above the geomembrane has a resistivity of ρ2. The clay layer under the geomembrane has a resistivity of ρ3. The electrode C1 is arranged in the garbage layer for power supply, and the electrode C2 is arranged at the lower part of the geomembrane away from the electrode system area. The electrode C2 can be regarded as a far pole.Because of the ρ1 > ρ2, the conductivity of the saturated leakage liquid layer at the upper part of the geomembrane is better than that of the landfill layer, so that there is almost no reflected current between the ρ1 layer and the ρ2 layer, that is, the current generated by the power supply electrode C1 is all transmitted to the ρ2 layer. Because of the ρ3 > ρ2, it can be considered that the interface between ρ2 layer and ρ3 layer has both a reflection current, and a transmission current through the leakage point. The potential generated at the detection electrode P1 under the geomembrane is formed by the action of transmission current. The total potential of point P1 is obtained by the superposition of the potential of point power supply passing through n leakage points at P1.The test adopts pole–pole arrangement, and the calculation formula of apparent resistivity is as follows:When there are loopholes in the geomembrane of the landfill, the leakage liquid will gradually penetrate into the soil layer under the geomembrane through the loopholes, resulting in the change of the conductivity of the soil layer under the geomembrane. The pole-pole acquisition mode of Se2432 parallel electrical instrument is used to obtain the original data  of each measuring point on the grid. After current normalization, the apparent resistivity of the soil layer is obtained. The electrical properties of different depths of the soil layer can be obtained by inversion of the apparent resistivity data of the soil layer, so as to determine the occurrence point and distribution range of leakage.The monitoring grid is 5 × 5. The spacing between measuring points is 0.08 m. The measurement method adopted by Se2432 parallel electric method instrument is cross diagonal measurement method. Figure No.1:ρNo.2:ρNo.3 = 5:3:10. If the four leakage points set by the model are regarded as four conductive resistors, the ratio of the current passing through the four leakage points is INo. 1:INo. 2:INo. 3:INo. 4 = 6:10:3:6.According to the experimental model and statistical data, the resistivity of the clay layer under the geomembrane is assumed ρ = 10 Ω· m, the resistivity ratio of tap water, NaCl solution and ethanol solution after penetrating into the soil layer ρThe calculation model is 10 × 10 grid, and the spacing of measuring points is 0.05 m. The potential value on each measuring point is calculated according to Eq. Figure No.1:ρNo.2:ρNo.3 = 20:15:24, the ratio of the current passing through the four leakage points is INo.1:INo.2:INo.3:INo.4 = 6:8:5:6. And adjust the distance between the two points to 0.28 m. 12 × 12 grid was used for detection, and the spacing of detection points is 0.04 m. Calculate the potential value of each detection point according to Eq. The resistivity of the clay layer under the geomembrane is assumed ρ = 10Ω·m. In consideration of the mutual influence between the leachate and appropriately reduce its influence effect, the resistivity ratio of water, NaCl solution, and ethanol solution after penetrating into the soil layer is set as ρTheoretical calculation results show that when the distance between the leakage points is large and the distance between the detection points is small, the potentiometric method can detect the leakage position of various leachates well. At the same time, the diffusion range of different leachates in the same plane is roughly the same, and they all gradually diffuse outward from the center of the leakage point, and the potential value gradually decrease. Point 2 has the largest potential closed loop range, which also has a certain impact on the leakage points of adjacent points 1 and 3. Point 1 and point 4 are water leakage. Affected by different leakage liquids, the leakage electric field of the two same leakage liquids is obviously different. The potential closed loop range of point 1 is larger than that of point 4. Point 3 is the leakage of ethanol solution. Because its resistance is the largest, the range of potential closed loop is the smallest.Figure Figure Figure Point 2 forms a closed loop of anomaly potential contour much higher than the background electric field, while the value of potential contour coil at leakage point 3 is lower than the surrounding value. It can be analyzed that positions 2 and 3 are leakage points. The leachate at point 2 is a high concentration NaCl solution containing more conductive particles, which will reduce the resistivity of the soil layer under the geomembrane at point 2. Thus, the passing current is increased to form a high potential closed loop. The leachate at point 3 is ethanol solution, which will increase the resistivity of the soil layer under the geomembrane at point 3. So as to reduce the passing current and form a low potential closed loop. Figure During the monitoring process, the leachate was continuously released from the injection pipe, and the results reflected the dynamic characteristics. Figure Compared with the surrounding potential contours, the difference is more obvious. Figure Figure Figure The potential value of each electrode was monitored after 2 h of leakage, and the resistivity profiles at different positions were obtained by the potential difference method.It can be seen from Fig. Monitoring for potential leaks is necessary. Soil and groundwater sampling through borehole surveys is expensive and discrete single-point data that is difficult to spatially interpret. In this paper, according to the research status of landfills, an indoor physical model test of multiple leachate and multiple leakage points is designed and made. Firstly, the experimental model is theoretically solved, and then the leakage process of the three leachates is monitored in real time. The calculation results were calculated using the potential method and the potential difference method, and the following conclusions were drawn:In order to achieve better monitoring accuracy and highlight the migration range of leachate, especially for landfills in areas with heavy rainfall and rainy season climate, the density of electrode grids should be increased because a large amount of precipitation further affects the migration of leachate. In this way, when using the potential difference method to solve, the effective area of the longitudinal section will increase to reflect the leakage migration when edge leakage occurs. Theoretical calculations show that the potential method and the three-dimensional inversion program can well reflect the location, number and distribution of leaks at different depths. For more types of leachate, further experiments will be carried out at a later stage to obtain more comprehensive monitoring results.The application of test results is often limited due to many uncontrollable factors that may affect the accuracy of field testing. The physical model produced can monitor the leachate migration law at varying flow rates. The properties of the clay layer under the geomembrane have a significant effect on the law of leakage and migration. During the actual construction of the landfill, the clay layer under the geomembrane should be as uniform as possible. When there are few abnormal areas of the background electric field in the soil layer, the monitoring point data is more accurate in judging the leakage point. The migration of leachate on the horizontal plane and each longitudinal section can also be obtained, with better sensitivity and a better description of the plume range of the leakage point. The difference between high resistance and low resistance in the abnormal area is convenient for the selection of different types of pollutants in the later stage.In the early stage of leakage, the leachate mainly migrates laterally. Longitudinal migration increases when soil moisture content increases. The water pressure of the leachate has a great influence on the leakage process. When the water pressure of the leachate is large, the measurement results are not easy to distinguish the location of different leakage points. When the hydraulic pressure is low, the location of the leak point in the monitoring results will become more obvious. This method is an effective way for leachate monitoring.