Positive Polarity Research Articles

Influence of Rain on the Support Insulation Electrical Strength

The article presents the results of studying the influence of artificial rain on the electrical strength of an extra high voltage support insulation column containing insulators of different heights when subjected to positive polarity switching impulses. It has been found that, in general, rain has an adverse effect on the support insulation discharge characteristics, which is associated with the occurrence of cascading overlaps from the screen fittings along the insulation structure components. The adverse effect caused by rain tends to aggravate with increasing the column upper element structural height, the switching impulse front time, and rainwater conductivity. As a result, the support insulation electrical strength may drop by as much as 40%. The reason for such a significant effect is the external electric field redistribution along the columns. On the one hand, the presence of a relatively high conductivity water film on the insulator surface when subjected to impulses with a front time of several milliseconds leads to an almost uniform distribution of voltage across insulation structural elements. On the other hand, sharp field strength spikes of the opposite polarity arise on the water droplets and trickles formed at the edges of neighboring sheds, which facilitates the occurrence of spark overlaps across a number of shed spacing distances, weakening of air insulation, and a decrease of structural discharge voltage. Measures to increase the support insulation electrical strength under rain conditions are proposed.

Embodiment of color metaphor: an image-based visual analysis of the Chinese color terms hēi ‘black’ and bái ‘white’

AbstractPerceptual information includes sensorimotor and emotional experience regarding the multimodality of the perceptual system. The current study provides an image-based visual analysis on the embodiment of color metaphors through the investigation of (i) the perceptual (dis)similarities between the literal and metaphorical meanings of the Chinese color terms hēi ‘black’ and bái ‘white’ and (ii) the influence of emotional valence on the degree of their perceptual (dis)similarities. Specifically, 24 concepts in three semantic domains were represented as eight-dimensional vectors based on the color information extracted from online images, including two color concepts of black and white, 20 abstract concepts referring to 8 metaphorical meanings of hēi and 12 metaphorical meanings of bái, and two abstract concepts referring to positive and negative affective polarity. Statistical analyses show that (i) the literal and metaphorical meanings of hēi and bái are perceptually distinguishable given their significant perceptual (dis)similarities and (ii) the observed perceptual distinguishability cannot be solely attributed to the (in)consistency of emotional valence associated with the senses. The present study provides nonlinguistic evidence for the embodiment of color metaphors in the Chinese context with an empirical approach that can simultaneously capture the metaphorical mappings and affective associations among cross-domain concepts with sensory data.

Key Modes of Ignition and Maintenance of Corona Discharge in Air

Theoretical and experimental studies of various modes of corona discharge operation in atmospheric pressure air are presented in this short review. The original results of modeling negative corona discharges are presented, taking into account the non-stationary plasma-chemical kinetics of charged particles in air plasma. The space–time evolution of the discharge in needle-to-plane geometry is investigated and analyzed. Several stages of discharge development are revealed from the moment of initiation of a low-negative current corona to the quasi-stationary mode of a glow discharge. Experimental data of the authors are presented. Modern technology and diagnostic equipment with a wide variation of the main parameters (the shape and polarity of the applied voltage, the type of gap, etc.) was used. The measurement of the optical characteristics of the plasma glow was carried out with high spatial resolution. Corona discharge current pulse profiles in the air at atmospheric pressure have been recorded with subnanosecond time resolution. With a positive polarity of the pin electrode and high voltage, a transition from a spherical streamer initiating a corona discharge to a cylindrical streamer is shown. The author’s results are rigorously evaluated through a critical comparison with findings from other research groups.

Enantioseparation and ecotoxicity evaluation of ibrutinib by Electrokinetic Chromatography using single and dual systems

In this work, two chiral methods enabling the separation of ibrutinib enantiomers were developed by Electrokinetic Chromatography. A cyclodextrin (CD) or a mixture of the CD and a chiral ionic liquid (CIL) was used as chiral selector. Using the single CD system, seven neutral and six anionic CDs were tested in a formate buffer at pH 3.0 working in positive and negative polarity, respectively. The use of sulfated-γ-CD (S-γ-CD) and negative polarity originated the best results considering analysis time and enantioresolution. The optimization of the experimental conditions allowed obtaining the separation of ibrutinib enantiomers in an analysis time of 4.2 min with an enantioresolution value of 1.5. The effect of the addition of fifteen CILs on the enantioresolution was evaluated showing that both analysis time and enantioresolution were generally increased. A mixture of S-γ-CD and [TMA][L-Lys] was selected which provided the separation of ibrutinib enantiomers in 8.1 min with an enantioresolution value of 3.3 under the same experimental conditions as in the case of using the single CD system. The enantiomeric impurity (S-ibrutinib) was the first-migrating isomer when using the single CD and the combined CD/CIL systems, as corresponds to the most desirable situation. Both chiral methods allowed the detection of the enantiomeric impurity up to a 0.1% as established by the International Council on Harmonization. After establishing the analytical characteristics of both chiral methodologies developed, they were applied to the enantiomeric determination of ibrutinib in a pharmaceutical formulation for hospital use marketed as pure enantiomer (R-ibrutinib) and to evaluate the stability and ecotoxicity of racemic ibrutinib and R-ibrutinib on Daphnia magna. The developed methodologies enabled, for the first time, the rapid chiral quantitation of ibrutinib in abiotic and biotic matrices.

Effects of background color, polarity and saturation on digital icon status recognition and visual search performance

Visual design form is an important factor affecting users' cognition of icons, which plays an important role in visual search and the perception of the status shown by icons. In the graphical user interface, the icon color is regularly used to indicate the running state of a function. The aim of this study was to investigate the effects of icon color features on user perception and visual search performance under different background colors. There were three independent variables in the study, including background color (white and black), icon polarity (positive and negative) and icon saturation (60%、80% and 100%). Thirty-one participants were recruited for the experiment. Task performance and eye movement results indicated that white background as well as positive polarity and 80% saturation icons brought the best performances. The findings of this study provide useful guidelines for designing more efficient and user-friendly icons and interfaces in the future.

The influence of asymmetrical bipolar pulses and interphase intervals on the bipolar cancellation phenomenon in the ovarian cancer cell line

The application of negative polarity electrical pulse (↓) following positive polarity pulses (↑) may induce bipolar cancellation (BPC), a unique physiological response believed to be specific to nanosecond electroporation (nsEP). The literature lacks analysis of bipolar electroporation (BP EP) involving asymmetrical sequences composed of nanosecond and microsecond pulses. Moreover, the impact of interphase interval on BPC caused by such asymmetrical pulse needs consideration. In this study, the authors utilized the ovarian clear carcinoma cell line (OvBH-1) model to investigate the BPC with asymmetrical sequences. Cells were exposed to pulses delivered in 10-pulse bursts but as uni- or bipolar, symmetrical, or asymmetrical sequences with a duration of 600 ns or 10 µs and electric field strength equal to 7.0 or 1.8 kV/cm, respectively. It was shown that the asymmetry of pulses influences BPC. The obtained results have also been investigated in the context of calcium electrochemotherapy. The reduction of cell membrane poration, and cell survival have been observed following Ca2+ electrochemotherapy. The effects of interphase delays (1 and 10 µs) on the BPC phenomenon were reported. Our findings show that the BPC phenomenon can be controlled using pulse asymmetry or delay between the positive and negative polarity of the pulse.

Hybrid ARDL-MIDAS-Transformer time-series regressions for multi-topic crypto market sentiment driven by price and technology factors

This paper develops a novel hybrid Autoregressive Distributed Lag Mixed Data Sampling (ARDL-MIDAS) model that integrates both deep neural network multi-head attention Transformer mechanisms, and a number of covariates, including sophisticated stochastic text time-series features, into a mixed-frequency time-series regression model with long memory structure. In doing so, we demonstrate how the resulting class of ARDL-MIDAS-Transformer models allows one to maintain the interpretability of the time-series models whilst exploiting the deep neural network attention architectures. The latter may be used for higher-order interaction analysis, or, as in our use case, for design of Instrumental Variables to reduce bias in the estimation of the infinite lag ARDL-MIDAS model. Our approach produces an accurate, interpretable forecasting framework that allows one to forecast end-of-day sentiment intra-daily, with readily attainable time-series regressors. In this regard, we conduct a statistical time-series analysis on mixed data frequencies to discover and study the relationships between sentiment from our custom stochastic text time-series sentiment framework, alternative popular sentiment extraction frameworks (BERT and VADER), and technology factors, as well as to investigate the role that price discovery has on retail cryptocurrency investors’ sentiment (crypto sentiment). This is an interesting time-series modelling challenge as it involves working with time-series regression models in which the time-series response process, and the regression time-series covariates, are observed at different time scales. Specifically, a detailed real-data study is conducted where we explore the relationship between daily crypto market sentiment (of positive, negative and neutral polarity) and the intra-daily (hourly) price log-return dynamics of crypto markets. The sentiment indices constructed for a variety of “topics” and news sources are produced as a collection of time-series capturing the daily sentiment polarity signals for each “topic”, namely each particular market or crypto asset. Different sentiment methods are developed in a time-series context, and utilised in the proposed hybrid regression framework. Furthermore, technology factors are introduced to capture network effects, such as the hash rate which is an important aspect of the money supply relating to the mining of new crypto assets, and block hashing for transaction verification. Throughout our real data study, we provide guidance and insights on how to use our hybrid model to combine—in a transparent, non-black-box way—covariates obtained with different time resolutions, how to understand the arising dynamics between these covariates, potentially under the presence of long memory structure, and, finally, successfully leverage these in forecasting applications. The hybrid model developed demonstrated superior performance to alternatives in both in-sample and forecasting application on real data.

Guest Editorial: Polymer electrets and ferroelectrets

Guest Editorial: Polymer electrets and ferroelectrets

Zeeman Doppler imaging ofξBoo A and B

Aims.We present a magnetic-field surface map for both stellar components of the young visual binaryξBoo AB (A: G8V, B: K5V).Methods.We employed high-resolution Stokes-Vspectra obtained with the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT). We inverted StokesVline profiles with ouriMAP software and compared them with previous inversions. We employed an iterative regularization scheme without the need for a penalty function and incorporated a three-component description of the surface magnetic-field vector. The spectral resolution of our data is 130 000 (0.040–0.055 Å) and we obtain a signal-to-noise ratio (S/N) of up to 3000 per pixel depending on wavelength. We used a singular-value decomposition (SVD) of a total of 1811 spectral lines to average Stokes-Vprofiles. Our mapping is accompanied by a residual bootstrap error analysis.Results.We constructed magnetic flux densities of the radial field component forξBoo A andξBoo B of up to plus or −115±5 G and 55±3 G, respectively. The magnetic morphology ofξBoo A is characterized by a very high latitude, nearly polar spot of negative polarity and three low-to-mid-latitude spots of positive polarity, while that ofξBoo B is characterized by four low-to-mid-latitude spots of mixed polarity. No polar magnetic field is reconstructed for the coolerξBoo B star. Both our maps are dominated by the radial field component, containing 86% and 89% of the magnetic energy ofξBoo A and B, respectively. We find only weak azimuthal and meridional field densities on both stars (plus or −15–30 G), about a factor two weaker than what was seen previously forξBoo A. The phase averaged longitudinal field component and dispersion is +4.5±1.5 G for ξ Boo A and −5.0±3.0 G forξBoo B.

Exploring Customers’ Feedback on the Technological and Operational Changes at the Departments of Motor Vehicles Due to Covid-19 Pandemic

In Early 2020, after COVID-19 was declared a pandemic, the Center for Disease Control and Prevention (CDC) provided guidelines to combat the spread of COVID-19. As a result, Departments of Motor Vehicles (DMVs) introduced several technological changes and modified operation protocols. This study explored the changes of customer feedback resulting from the changes in DMVs operations across the United States. A total of 24[Formula: see text]164 Google reviews were collected from 69 cities in 43 States. Sentiment analysis, text network, and logistic regression were applied to evaluate the changes of the feedback before and after the lockdown period. It was found that the post-lockdown reviews had higher positive polarity and low negative polarity than pre-lockdown reviews. Furthermore, positive feedback topics, such as excellent service and short waiting time, increased significantly during the post-lockdown era. Keywords that showed a higher likelihood of higher ratings include appointment, wait time, and minutes. Conversely, lower ratings were associated with keywords — customer services, hours, and people, among others. Further, the logistic regression showed that the odds of high ratings increased nearly three times when COVID-19-related keywords were mentioned. Several recommendations to improve operations are presented in this study. It is expected that the findings will benefit DMV operators and policymakers across the United States.

Charge-Sign Dependent Cosmic-Ray Modulation Observed with the Calorimetric Electron Telescope on the International Space Station.

We present the observation of a charge-sign dependent solar modulation of galactic cosmic rays (GCRs) with the Calorimetric Electron Telescope onboard the International Space Station over 6yr, corresponding to the positive polarity of the solar magnetic field. The observed variation of proton count rate is consistent with the neutron monitor count rate, validating our methods for determining the proton count rate. It is observed by the Calorimetric Electron Telescope that both GCR electron and proton count rates at the same average rigidity vary in anticorrelation with the tilt angle of the heliospheric current sheet, while the amplitude of the variation is significantly larger in the electron count rate than in the proton count rate. We show that this observed charge-sign dependence is reproduced by a numerical "drift model" of the GCR transport in the heliosphere. This is a clear signature of the drift effect on the long-term solar modulation observed with a single detector.

Effect of Display Polarity on Amplitude of Accommodation and Visual Fatigue

This study aimed to assess the changes in the amplitude of accommodation under different display polarities and ascertain the effect of display polarities on visual fatigue. Thirty subjects randomly underwent a reading task for 30 minutes with both positive and negative display polarities. The amplitude of accommodation was measured, and subjects were required to complete a subjective symptoms questionnaire; both before and after the reading task. The amplitude of accommodation and visual fatigue symptoms were significantly reduced after the reading task, with both display polarities.

Formation mechanisms of striations in a filamentary dielectric barrier discharge in atmospheric-pressure argon

Formation mechanisms of striations along the discharge channel of a single-filament dielectric barrier discharge (DBD) in argon at atmospheric pressure are investigated by means of a time-dependent, spatially two-dimensional fluid-Poisson model. The model is applied to a one-sided DBD arrangement with a 1.5 mm gap using a sinusoidal high voltage at the powered metal electrode. The discharge conditions are chosen to mimic experimental conditions for which striations have been observed. It is found that the striations form in both half-periods during the transient glow phase, which follows the streamer breakdown phase. The modelling results show that the distinct striated structures feature local spatial maxima and minima in charged and excited particle densities, which are more pronounced during the positive polarity. Their formation is explained by a repetitive stepwise ionisation of metastable argon atoms and ionisation of excimers, causing a disturbance of the spatial distribution of charge carriers along the discharge channel. The results emphasise the importance of excited states and stepwise ionisation processes on the formation of repetitive ionisation waves, eventually leading to striations along the discharge channel.

Ripples and Rush-to-the-Poles in the Photospheric Magnetic Field

The distribution of magnetic fields of positive and negative polarities over the surface of the Sun was studied on the basis of synoptic maps presented by the NSO/Kitt Peak (1978-2016). To emphasize the contribution of weak fields the following transformation of synoptic maps was made: for each synoptic map only magnetic fields with modulus less than 5G ($|B|\leq 5$G) were left unchanged while larger or smaller fields were replaced by the corresponding threshold values +5G or $-5$G. Cyclic variations of the magnetic field polarity have been observed associated with two types of magnetic field flows in the photosphere. Rush-to-the-Poles (RTTP) appear near the maximum of solar activity and have the same sign as the following sunspots. The lifetime of RTTP is $\sim 3$ yrs, during which time they drift from latitudes $30^\circ$-$40^\circ$ to the pole, causing the polarity change of the Sun's polar field. Our aim is the study of another type of variations which has the form of series of flows with individual flows of 0.5-1 yr with alternating polarity. These flows called ripples are located in time between two RTTP and drift from the equator to the latitudes of $~50^\circ$. The period of variation of ripples was shown to be 1.1 yr for the northern hemisphere and 1.3 yr for the southern hemisphere. It was found that the amplitude of variation was higher for the time intervals where the polar field had a positive sign. Within the same flow, fields of positive and negative signs developed in anti-phase. Two types of flows - RTTP and ripples - together formed a unique structure which had close connection to the magnetic solar cycle.

Hybrid Encoding Evolutionary Algorithm for Reversible Logic Synthesis

Variable-length encoding evolutionary algorithm has been proved effective in small and medium-sized reversible logic synthesis. Variable-length chromosome is adopted because the length of optimal reversible circuit is unknown. However, it leads to huge search space. The improved two-stage hybrid encoding synthesis is proposed to reduce the search space and enhance the feasible ratio. Fixed and variable-length encoding are applied in the two stages respectively. Estimated maximum length is obtained through heuristic information from the positive polarity Reed Muller spectra and the fixed chromosome length in the first stage is set to a value less than the maximum one. When the population converges in the first stage and the feasible solution has not found, the second stage starts to work. It employs the original variable-length encoding algorithm, but the optimization problem is simplified through the reduced positive polarity Reed Muller spectra of the best solution from the first stage. Experimental results show that both the fixed-length encoding and the simplified fitness function in the two stages both can decrease the search space and save the synthesis time.

A critical study of ideologies in selected Boko Haram videos

Boko Haram insurgency has threatened the existence of Nigeria as the group has wrecked serious havoc on different parts of the country. This group has constantly claimed to stand against some issues, ideas, people, doctrines, and systems. They have demonstrated this in their activities. To further their engagements, they periodically release videos to the public and these videos communicate layers of meaning and ideologies. This study, therefore, highlights and discusses the ideologies inherent in Boko Haram Video. A total of five videos were selected from the Sahara Reporters TV, Premium Times, and legit.ng using a purposive sampling technique. The study adopted Fairclough’s Three Dimensional model of Critical Discourse Analysis as its theoretical leaning. Findings revealed that Boko Haram used both verbal and nonverbal semiotic resources in conveying their ideologies. Words like “infidels, tyrants, idiots, pagans and thieves” are used by Abubakar Shekau to show the negative out-group polarity of others while discourse elements like “we follow Allah, we obey Qur’an” are used to show positive in-group polarity. Various shots and expressions convey Boko Haram ideologies including monotheism, absolutism, anti-westernism, and masculinism. The study concludes that the semiotic resources used in Boko Haram videos covertly convey ideologies, power, (mis)representation and hegemony. Therefore, it is cogent that Nigeria’s federal government and the Nigerian military pay attention to the understanding of the operational ideologies of Boko Haram for effective deradicalisation of the sect and successful eradication of Boko Haram insurgency.

Automated Detection of Central-positive Complexes & Postictal Generalized EEG Suppression in ECT-induced Seizures – An Illustrative Case Report (P10-1.009)

<h3>Objective:</h3> We present a case of using automated algorithms to analyze central-positive complexes (CPCs) and postictal generalized electroencephalographic suppression (PGES) in the context of ECT-induced seizures. Our goal is to characterize peri-ictal EEG changes in ECT-induced seizures to define their unique features as generalized seizures. <h3>Background:</h3> Generalized seizures induced by electroconvulsive therapy (ECT) have been proposed as a model to study epileptic seizures in humans. We recently described generalized, high-amplitude waveforms with maximum positive voltage over the vertex (CPCs) during ECT-induced seizures. Furthermore, we developed an automated algorithm for detecting postictal PGES, defined as electroencephalographic (EEG) activity of ≤10 mV following a generalized seizure. <h3>Design/Methods:</h3> This investigation is a secondary analysis of data collected from Reconstructing Consciousness and Cognition Phase 2 study (ClinicalTrials.gov NCT02761330). A 53-year-old female with a diagnosis of major depressive disorder underwent 5 sessions of right unilateral ECT during concurrent 64-channel EEG recordings. Quantitative EEG analysis allowed for assessment of spatiotemporal properties and spectral content during the peri-ictal period. CPC and PGES durations, quantified by automated algorithms, were compared to those derived through visual interpretation by expert epileptologists. <h3>Results:</h3> CPCs occurred during Phase III of all recorded seizures, with a median duration of 41 seconds. CPC evolved from 4.1 to 3.2 Hz as the seizures progressed. Peak-amplitude CPC scalp topology was consistent across patient’s seizures, showing maximal positive polarity over the vertex and surrounding regions and maximal negative polarity over the subocular electrodes. PGES duration lasted 5–45 seconds (median of 22 seconds) following the seizure and the median time to responsiveness after the seizure was 18.3 minutes. The findings using the automated algorithm were comparable to manual visual interpretation. <h3>Conclusions:</h3> This case presents the utility of automated algorithms to analyze CPCs and PGES characteristics, many of which were comparable to those evaluated through visual EEG interpretation. <b>Disclosure:</b> Dr. Nayak has nothing to disclose. Dr. Kafashan has nothing to disclose. Dr. Nascimento has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Zogenix. The institution of Dr. Nascimento has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Biocodex. Dr. Nascimento has received personal compensation in the range of $500-$4,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for AAN. The institution of Dr. Nascimento has received research support from Zogenix. The institution of Dr. Nascimento has received research support from Biocodex. The institution of Dr. Nascimento has received research support from Greenwich. Dr. Nascimento has received publishing royalties from a publication relating to health care. Dr. Nascimento has a non-compensated relationship as a Editorial Team Member with Neurology RFS that is relevant to AAN interests or activities. Dr. Nascimento has a non-compensated relationship as a Production Team with Neurology Podcast that is relevant to AAN interests or activities. The institution of Dr. Palanca has received research support from National Institutes of Health. The institution of Dr. Palanca has received research support from McDonnell Center for Systems Neuroscience. The institution of Dr. Palanca has received research support from American Federation for Suicide Prevention. Dr. Palanca has received intellectual property interests from a discovery or technology relating to health care. Dr. Palanca has received personal compensation in the range of $100,000-$499,999 for serving as a Employee with Washington University School of Medicine in St. Louis. Dr. Hogan has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Neurelis. The institution of Dr. Hogan has received research support from Biogen Inc. The institution of Dr. Hogan has received research support from Engage Therapeutics. The institution of Dr. Hogan has received research support from Otsuka Pharmaceuticals. The institution of Dr. Hogan has received research support from Cerevel Therapeutics.

Outstanding photoelectrical response in BiFeO3 hollow microspheres deposited by ultrasonic spray pyrolysis technique

Nowadays, it is well known that BiFeO3 exhibits a low photoresponse and, in consequence, small short-circuit current density (Jsc≪μA/cm2). This event is considered a problem for which multiple solutions have been explored, from the formation of complex heterostructures, as well as doping with several materials, alternatives that are expensive and, in many cases, complicated. In this context, we report a simple and low-cost technique (Spray Pyrolysis) that has been carried out to obtain microstructures forming hollow BiFeO3 spheres and circular flower-shaped composed by BiFeO3-Bi2O3 with an outstanding photoresponse. These microstructures show a photocurrent increase of more than six magnitude orders (Jsc=3.5 mA/cm2) and an external quantum efficiency reaching a maximum value of 10.7% at a wavelength of 431 nm applying 0 V (photovoltaic effect). Furthermore, a photoresponse variation is also observed when applying positive or negative electrical polarization. The improvement of the photoelectrical response is attributed to the structure type, composition and the oxygen vacancies present by the same process of formation of these microstructures, which is discussed as an Ostwald ripening and a Kirkendall diffusion process. The morphology of the described microstructures was observed using scanning electron microscopy (SEM), while the structural and compositional analysis were performed using X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) techniques. In the case of electrical measurements, an ITO/BFO/Si-n heterojunction was fabricated being this heterojunction formed by intrinsic semiconductor (perovskite) and an n-type oxide semiconductor (ITO).

Effect of Positive Polarity in an Inertial Electrostatic Confinement Fusion Device: Electron Confinement, X-Ray Production, and Radiography

The conventional inertial electrostatic confinement fusion (IECF) operation is based on the application of high negative voltage to the central grid, which results in the production of neutrons due to the fusion of lighter ions. The device can also be used as an X-ray source by altering the polarity of the central grid. In this work, electron dynamics during the positive polarity of the central grid are studied using the object-oriented particle-in-cell code XOOPIC. The simulated trapped electron density inside the anode is found to be on the order of 1016 m when 10 kV is applied to the anode. The recirculatory characteristics of the electrons are also studied from the velocity distribution function. A scintillator-based photomultiplier tube is used to detect the produced X-ray. The X-ray-emitting zones of the device are investigated by pinhole imaging techniques. Last, the radiography of metallic as well as biological samples are reported in the later part of this paper. This study shows the utilization of the IECF device when the polarity of the central grid is reversed.

Ultra-high-resolution observations of persistent null-point reconnection in the solar corona

Magnetic reconnection is a key mechanism involved in solar eruptions and is also a prime possibility to heat the low corona to millions of degrees. Here, we present ultra-high-resolution extreme ultraviolet observations of persistent null-point reconnection in the corona at a scale of about 390 km over one hour observations of the Extreme-Ultraviolet Imager on board Solar Orbiter spacecraft. The observations show formation of a null-point configuration above a minor positive polarity embedded within a region of dominant negative polarity near a sunspot. The gentle phase of the persistent null-point reconnection is evidenced by sustained point-like high-temperature plasma (about 10 MK) near the null-point and constant outflow blobs not only along the outer spine but also along the fan surface. The blobs appear at a higher frequency than previously observed with an average velocity of about 80 km s−1 and life-times of about 40 s. The null-point reconnection also occurs explosively but only for 4 minutes, its coupling with a mini-filament eruption generates a spiral jet. These results suggest that magnetic reconnection, at previously unresolved scales, proceeds continually in a gentle and/or explosive way to persistently transfer mass and energy to the overlying corona.