Polarity Time Research Articles

Experimental analysis of a rotating cylinder electrode reactor: Hydrodynamics and mass transport

AbstractThis report deals with the hydrodynamic and mass transport characterization in an rotating cylinder electrode (RCE) in continuous and batch configuration employing relatively simple techniques like obtaining the mixing time, polarization, and residence time distribution (RTD) curves. For batch configuration, the limiting current and Sh values were higher than for continuous configuration, indicating that the mixing pattern is influenced by possible flow inhomogeneities during the operation as a continuous mixing stirrer. This could diminish the amount of electroactive reactant that reaches the electrode surface, due to the possible shrinking of recirculation zones during the rotation of the cylindrical stirrer, forming channeling and by‐pass flow zones. These results could evidence the existence of slight deviations from the ideal mixer and other non‐ideality flow zones associated with the width of curves upon analyzing age function through RTD curves, at the different flow rates employed in continuous configurations.

Fabrication, thermal, mechanical, and piezoelectric characterization of PLA/BT piezocomposites

Abstract The properties of polylactide (PLA) composites containing up to 40 vol% of barium titanate (BT) powder were investigated. PLA/BT composites were fabricated using twin-screw extrusion, which ensured uniform filler dispersion. The results demonstrated that increasing the BT content in PLA improved the thermal stability, stiffness, and degree of crystallinity of the composite. The piezoelectric coefficient d33 also increased with higher BT content and longer polarization times, reaching a maximum value of 35 pC/N for composites containing 40 vol% BT. Additionally, the studies revealed that the d33 coefficient is pressure dependent. Presented PLA/BT piezocomposites highlight the suitability of these materials for applications that require both biocompatibility and piezoelectric functionality, including regenerative medicine, energy harvesting, soft robotics, and electroactive biomedical devices.

Activation thresholds for electrical phrenic nerve stimulation at the neck: evaluation of stimulation pulse parameters in a simulation study

Abstract Objective. Phrenic nerve stimulation reduces ventilator-induced-diaphragmatic-dysfunction, which is a potential complication of mechanical ventilation. Electromagnetic simulations provide valuable information about the effects of the stimulation and are used to determine appropriate stimulation parameters and evaluate possible co-activation. Approach. Using a multiscale approach, we built a novel detailed anatomical model of the neck and the phrenic nerve. The model consisted of a macroscale volume conduction model of the neck with 13 tissues, a mesoscale volume conduction model of the phrenic nerve with three tissues, and a microscale biophysiological model of axons with diameters ranging from 5 to 14 µm based on the McIntyre–Richardson–Grill-model for myelinated axons. This multiscale model was used to quantify activation thresholds of phrenic nerve fibers using different stimulation pulse parameters (pulse width, interphase delay, asymmetry of biphasic pulses, pulse polarity, and rise time) during non-invasive electrical stimulation. Electric field strength was used to evaluate co-activation of the other nerves in the neck. Main results. For monophasic pulses with a pulse width of 150 µs, the activation threshold depended on the fiber diameter and ranged from 20 to 156 mA, with highest activation threshold for the smallest fiber diameter. The relationship was approximated using a power fit function x −3. Biphasic (symmetric) pulses increased the activation threshold by 25 to 30 %. The use of asymmetric biphasic pulses or an interphase delay lowered the threshold close to the monophasic threshold. Possible co-activated nerves were the more superficial nerves and included the transverse cervical nerve, the supraclavicular nerve, the great auricular nerve, the cervical plexus, the brachial plexus, and the long thoracic nerve. Significance. Our multiscale model and electromagnetic simulations provided insight into phrenic nerve activation and possible co-activation by non-invasive electrical stimulation and provided guidance on the use of stimulation pulse types with minimal activation threshold.

Electrochemical HOCl Production Modeling for an Electrochemical Catheter.

Hypochlorous acid (HOCl) is a strong oxidizing agent that damages cells by interacting with lipids, nucleic acids, sulfur-containing amino acids, and membrane components. It is an endogenous substance produced by the immune system to protect mammals from pathogens. Previously, we developed an HOCl-generating electrochemical catheter (e-catheter) and demonstrated its ability to prevent central line-associated bloodstream infections. The e-catheter is an electrochemical system consisting of two parts - an e-hub and a tube. Working, counter, and reference electrodes are placed in the e-hub, which contains 0.9% NaCl as an electrolyte. Although a prototype of this device has shown activity against pathogens, it is helpful to understand the factors influencing associated electrochemical/chemical processes to optimize design and efficacy. A mathematical model could predict factors influencing HOCl generation and distribution in the catheter and could aid in optimizing these devices. Here, we developed an Electrochemical Hypochlorous Acid Production (EHAP) model to predict factors influencing electrochemical generation and distribution of HOCl in e-catheters, including polarization time, diffusion of HOCl into the e-catheter, operational voltage, working electrode length, and surface area.

Breaking Down Stereotypes by Realizing Women’s Interests: Gender and Its Impact on Legislative Consensus

The presence of women in legislatures has steadily increased over the past 2 decades, prompting numerous studies to explore the role of women in politics. This article focuses on Spain to analyze how women contribute to parliamentary consensus, a rarely explored but necessary topic in times of polarization and political conflict. The combination of aggregated and member of parliaments’ individual-level data provides a holistic approach to assessing how women operate in legislatures and their predisposition to political conflict. Aggregated findings show that an increase in female political representation does not go hand in hand with more legislative consensus, only when gender laws are approved. Similarly, the individual-level results show the importance of political parties in shaping attitudes toward conflict. Female parliamentarians present less consensual attitudes in the most extreme ideological parties: Podemos and VOX. However, no gender differences exist in the mainstream parties of the PSOE (Spanish Socialist Workers’ Party) and PP (People’s Party). These findings also highlight the institutional and party barriers that women may face when developing their “know-how” in politics.

Self-Adhesive and Self-Sustainable Bioelectronic Patch for Physiological Feedback Electronic Modulation of Soft Organs.

Bionic electrical stimulation (Bio-ES) aims to achieve personalized therapy and proprioceptive adaptation by mimicking natural neural signatures of the body, while current Bio-ES devices are reliant on complex sensing and computational simulation systems, thus often limited by the low-fidelity of simulated electrical signals, and failure of interface information interaction due to the mechanical mismatch between soft tissues and rigid electrodes. Here, the study presents a flexible and ultrathin self-sustainable bioelectronic patch (Bio-patch), which can self-adhere to the lesion area of organs and generate bionic electrical signals synchronized vagal nerve envelope in situ to implement Bio-ES. It allows adaptive adjustment of intensity, frequency, and waveform of the Bio-ES to fully meet personalized needs of tissue regeneration based on real-time feedback from the vagal neural controlled organs. With this foundation, the Bio-patch can effectively intervene with excessive fibrosis and microvascular stasis during the natural healing process by regulating the polarization time of macrophages, promoting the reconstruction of the tissue-engineered structure, and accelerating the repair of damaged liver and kidney. This work develops a practical approach to realize biomimetic electronic modulation of the growth and development of soft organs only using a multifunctional Bio-patch, which establishes a new paradigm for precise bioelectronic medicine.

Chitosan/Microcrystalline Cellulose Overlaid rGO/Fe3O4 Films: Broadband Dielectric Spectroscopy Investigations

Hybrid and straightforward inorganic/organic composites that can be used simultaneously for energy storage are reported. Films from chitosan (Cs) with microcrystalline cellulose (MCC) implanted with reduced graphene oxide (rGO) and/or magnetic Fe3O4 nanoparticles were fabricated. The reinforcement of the Cs/MCC films with rGO and /or Fe3O4 was studied through Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy with energy dispersive electron spectroscopy. In addition, their magnetic, conductivity, dielectric constant, and dielectric loss behaviors were studied. The magnetic investigations of the two films loaded with Fe3O4 have supper paramagnetic behavior. The saturation magnetization was decreased with the presence of rGO. At lower frequencies, the contribution of charge transport and interfacial polarization causes a sudden and nearly linear increase in permittivity with decreasing frequency. Unfortunately, no indication of electrode polarization was found, which reduces the ability of the prepared composition to store electrical energy. The electric modulus representation was employed to determine the relaxation time of the interfacial polarization quantitatively and numerically. No indication of electrode polarization was found.

Investigation of machining performance of waspaloy using copper-graphite composite electrodes in electric discharge machining

Abstract This study endeavoured to investigate the machining of Waspaloy using Electric Discharge Machining (EDM), utilizing copper-graphite composites as the tool material. Given the limited existing research on machining Waspaloy with composite tools, this study aims to address this gap by employing a copper-graphite composite tool. In this work, pure copper electrode and three composite electrodes with varying graphite percentages in copper, viz. copper containing 5%, 10%, and 15% graphite (CuGr-5, CuGr-10, and CuGr-15), are utilized for experimentation. Composite electrodes are fabricated by the stir-casting process. The scanning electron microscope reveals that the graphite specks are homogeneously disseminated over the matrix material. The Taguchi mixed orthogonal array was used for developing experimental runs. By varying the current, polarity, pulse on and off times, tool materials, and gap, machining performance was measured in terms of Material Removal Rate (MRR), Tool Wear Rate (TWR), and Surface Roughness (Ra). It was observed that CuGr-5 provides an enhancement in MRR due to the improved electric conductivity, bridging effect, and increased energy concentration at the spark gap. Diverse characteristics witnessed on the surface morphology include black dots, globules, remelted layers, micro-cracks, and scratches. When machined with a CuGr5 electrode, the surface quality improved owing to the completed flushing and uniform distribution of generated heat as confirmed through worn surface morphology. The parameters were optimized utilizing the PROMETHEE optimization technique; it was found that the CuGr-5 electrode with the assessment value 0.02458 was optimal for machining of Waspaloy.

Advancing polar motion prediction with derivative information

Abstract Earth Orientation Parameters (EOP) are essential for monitoring Earth’s rotational irregularities, impacting satellite navigation, space exploration, and climate forecasting. This study introduces a hybrid prediction model combining least-squares (LS) and vector autoregression (VAR) to improve Earth’s Pole Coordinates (x, y) forecast accuracy. Using daily sampled IERS EOP 20 C04 data from 2013 to 2023, we conducted 1,000 yearly random trials, performing 48 forecasts per year. Our method evaluates six data combinations, including primary variables (x, y) and their derivatives ( x ̇ , y ̇ $\dot{x},\dot{y}$ ). Results show a systematic improvement in prediction accuracy, especially for ultra-short-term forecasts (10 days into future), with derivative information stabilizing the solutions. The best-performing combination ( x , y , x ̇ , y ̇ $x,y,\dot{x},\dot{y}$ ) achieved a mean absolute prediction error (MAPE) reduction (with respect to the reference data combination – x, y) of up to 8 % for the y and 7 % for the x over a whole 30-day forecast horizon. These findings highlight the effectiveness of incorporating derivatives of polar motion time series into prediction procedure.

Small-scale segmented fault rupture along the East Anatolian fault during the 2023 Kahramanmaraş earthquake

Rupture velocity affects the shaking damage potential of an earthquake, but it is hard to estimate. Here we track the rupture front of the first 25 s of the 2023 Kahramanmaraş earthquake using the P-wave polarization vector vs time as measured by the dense three-component accelerometer network surrounding the slipping fault. We find a coherent increase of the rupture velocity along portions of the fault zone where high coseismic slip has been previously mapped. This is detected in a domain of the Pazarcık segment of the East Anatolian fault at 40 km NE of the mainshock epicenter where the rupture becomes super-shear. This domain spatially matches the part of the Pazarcık segment where most micro-earthquakes nucleate in the inter-seismic phase and edges at north a nearly aseismic domain. We postulate the existence of a velocity-weakening subsegment on the Pazarcık fault sandwiched between velocity-strengthening domains and/or mechanic barriers to the fault slipping.

Treading the Narrow Path – Rethinking Democratic Education in Times of Polarization

Abstract This essay examines the relationship between knowledge, politics, and education in the context of the global crisis of democracy and the growing prevalence of political polarization. Focusing on the issue of vaccine hesitancy, I explore how citizens’ reference to knowledge and values shapes their political judgements and argue for the importance of education in facilitating informed and reasoned decision-making. Drawing on Hannah Arendt’s dialectical account of politics and knowledge, I highlight the limitations of reducing political debates to a quest for ‘right knowledge’, arguing that it neglects the coordination of diverse values and interpretations that is essential to democratic processes. To do so, I discuss ‘educationalization’ of the political during the COVID-19 pandemic, wherein the dissemination of empirically grounded information became a strategy to generate public consent. However, my essay cautions against the hegemony of empirical knowledge, which can lead to despotic politics and the proliferation of misinformation. To ensure differentiated and reasonable judgements in uncertain situations and conflicts, I turn to Arendt’s concept of reflective and political judgement, emphasizing the ability to imagine others’ perspectives and construct general principles. The educational task, therefore, encompasses not only conveying factual knowledge but also nurturing reflective judgement that strikes a balance between factual truth and divergent interpretations, values, and interests.

Effect of Alkali Metal Cations and Trace Metal Impurities on Cathodic Corrosion of Gold Electrode Surfaces

AbstractIn this work, we comprehensively studied the cathodic corrosion of Au electrodes as a function of the identity of alkali metal hydroxides at different concentrations and various negative potentials. We reveal that the ratio of free water and water bound in hydration shells controls the overall cathodic corrosion behavior, alongside the specific adsorption of alkali metal cations. Moreover, we highlight the crucial role of electrolyte cleanliness, particularly regarding the presence of trace metal impurities. Interestingly, the presence of trace amounts of nickel and iron in as‐received CsOH suppresses cathodic corrosion by their deposition onto Au surfaces. In contrast, after purification the polarization of Au surfaces in 10 M CsOH leads to the formation of nanoporous surfaces with high electrochemically active surface area, in which the degree of porosity can be tuned by varying the polarization time at −1.6 V vs. RHE.

Chronostratigraphy and tectono‐sedimentary history of the Eastern South Pyrenean foreland basin (Ripoll Syncline, North‐East Spain)

AbstractThis paper contributes to an understanding of the tectono‐sedimentary evolution of the South Pyrenean foreland system by reviewing the chronostratigraphic framework of the basin infill in its eastern sector. Six sections are analysed and cross‐correlated to build a 6.5 km thick composite magnetostratigraphy that represents the complete record of the Cadí Nappe in the Ripoll Syncline. New and previous magnetostratigraphic sections are integrated with available biostratigraphy to provide a new age calibration of the sedimentary succession of the Cadí Nappe, encompassing from Palaeocene to Middle Lutetian age. The proposed correlation with the Geomagnetic Polarity Time Scale aims at best reconcile magnetostratigraphic data with the regional biochronology built on the marine Shallow Benthic Zonation (SBZ biozones), the continental mammalian biochronology (MP levels) and the newly collected charophyte data. A subsidence analysis was performed on the calibrated composite succession, resulting in two well‐defined intervals bounded by a hiatus. A Palaeocene to Early Eocene interval with low (11–21 cm/kyr) total subsidence rates, and an Early to Middle Eocene interval, characterised by high (70–75 cm/kyr) total subsidence rates. The detailed trends in both subsidence and sedimentation mark the development and evolution of the foreland depozones, from distal foreland depozones to foredeep and wedge‐top depozones, relative to the emplacement of the Pedraforca Nappe and Cadí Thrust Nappe. The most pronounced sedimentary shift in the Cadí Nappe occurred at 49 Ma, with the rapid drowning of the carbonate platforms and its transition into talus and deep basinal environments. Carbonate platforms collapsed and resedimented on the talus of the elongated trough, newly formed parallel to the orogenic front. This marked the onset of tectonic subsidence triggered by the submarine emplacement of the Lower Pedraforca Nappe. The emersion of the orogenic wedge drove the entry of siliciclastics, lagged by 1 Myr, into the Ripoll Trough. The foredeep filled rapidly (5.5 km thickness in less than 7 Myr) compared to other South Pyrenean regions, favoured by its semi‐enclosed palaeogeography. The emplacement of the Vallfogona Thrust as early as the Middle Lutetian (43 Ma) brought the Cadi Nappe into a wedge‐top setting. However, the Ripoll growth syncline continued acting as a temporary sink for alluvial sedimentation while a foredeep developed further south in the autochthonous Ebro Basin. The flexural response of the Iberian plate to the tectonic thickening of the Axial Zone counterbalanced for a period the local uplift of the Cadi Nappe, providing accommodation space for the top sediments filling the Ripoll Syncline.

U-Pb calcite ages date oblique rifting of the Arctic–North Atlantic gateway

Abstract Miocene breakup of Svalbard from Greenland formed a deep oceanic gateway that enabled circulation between the Arctic and Atlantic Oceans, significantly changing the global climate. However, the timing of events remains unclear. An excellent opportunity to constrain this timing is found onshore western Svalbard, where the Sarsbukta fault forms the eastern margin of the Eocene–Oligocene Forlandsundet basin. Here, we present new results from U-Pb dating of calcite precipitated in fault-related veins to constrain the timing of Sarsbukta fault deformation and the evolution of the basin. Our oldest calcite age is Permo-Triassic, suggesting long-lived deformation along the fault. A cluster of ages between 41 and 33 Ma overlaps with fossil-based depositional ages from parts of the Forlandsundet basin. These data indicate that onshore transtension partly pre-dated the well-established Chron 13 (magnetic polarity time scale; 35.5–33.7 Ma) reorganization of spreading ridges in the North Atlantic. Our youngest age of 13 Ma indicates that faulting persisted long after the preserved basin fill was deposited. If seafloor spreading marked the end of extension of continental crust, Molloy Ridge spreading during Chron 5 (19.6–9.8 Ma) may have initiated after 13 Ma.

Immigration status and adolescents’ voting intention in European countries: The importance of immigrant integration policy context

This article investigates whether policy efforts to integrate immigrants into society can have interpretive effects and motivate adolescents of immigrant origin in European countries to engage in the host country’s political system. We find that countries with more inclusive integration policies tend to have smaller gaps in voting intention between adolescents of immigrant origin and those not of immigrant origin, holding constant an array of individual and family politically relevant resources. Specifically, differences across countries in the inclusiveness of education policies appear to be a strong predictor of the magnitude of voting intention gaps between first-generation and native adolescents. In the case of second-generation vs. native gaps in voting intention, the inclusiveness of citizenship acquisition policies emerges as a key predictor. In these times of strong polarization and anti-immigration discourse across Europe, our findings are particularly relevant for policymakers and researchers in their efforts to address what might be done to help promote the long-term political integration of immigrants and their descendants.

Multifractal fluctuations in zebrafish (Danio rerio) polarization time series.

In this work, we study the polarization time series obtained from experimental observation of a group of zebrafish (Danio rerio) confined in a circular tank. The complex dynamics of the individual trajectory evolution lead to the appearance of multiple characteristic scales. Employing the Multifractal Detrended Fluctuation Analysis (MF-DFA), we found distinct behaviors according to the parameters used. The polarization time series are multifractal at low fish densities and their average scales with . On the other hand, they tend to be monofractal, and their average scales with for high fish densities. These two regimes overlap at critical density , suggesting the existence of a phase transition separating them. We also observed that for low densities, the polarization velocity shows a non-Gaussian behavior with heavy tails associated with long-range correlation and becomes Gaussian for high densities, presenting an uncorrelated regime.

Investigation on shear performance and prediction model of CFRP-ECC-concrete composite interface suffered from anodic polarization and environmental degradation

This study aims to investigate shear performance and prediction model of CFRP-ECC-concrete composite interface suffered from anodic polarization and environmental degradation. The effect of ECC mixtures, cathodic current densities, polarization period, and the duration of sulfate soaking and sulfate attacking by wet and dry cycles on the interface of the composite were studied. The results showed that three failure modes of CFRP-ECC-concrete composite interface were found. Shear load-slip curves showed double broken lines characteristics, while voltage-deterioration time curves showed an approximate linear increase relationship between voltage and polarization time. The five parameters all had significant effects shear strength deterioration on the CFRP-ECC-concrete composite interface. Moreover, this study proposed an innovative prediction model to the interfacial shear strength by the measured voltage, which can provide an important basic theory for ICCP-SS technology. This work makes a contribution to the ICCP-SS technology on the shear performance and prediction model of composite interface.

Study on the effect of different high-voltage electric field polarization process parameters on the vitality of dried chili pepper seeds

To study the effect of different high-voltage electric field polarisation treatment process parameters on the viability of seeds of dried chili peppers. In this study, a high-voltage electrostatic polarisation treatment system was constructed to carry out experiments on the effects of different high-voltage electric field polarisation treatment process parameters on the viability of dried chili seeds. Conduct one-way tests to determine the preferred polarisation method and the preferred interval for output voltage and polarisation time. Two-factor, five-level central combination test with output voltage and polarization time as test factors and seed conductivity as a response indicator. Determining the better combination of parameters for output voltage and polarization time; Conducting seed germination trials to validate the effectiveness of the polarisation process. The results of the one-way test showed that: Negative-voltage polarisation was more effective than positive-voltage polarisation and alternating positive–negative-voltage polarisation in promoting seed vigor, with a better output voltage in the range of 10–14 kV, and a better polarisation time in the range of 20–40 s; The results of orthogonal tests showed that: Under the condition of negative voltage polarisation treatment, the output voltage of 12.08 kV and polarisation time of 30.32 s was the better parameter combination, at which the seed conductivity was minimum 159.87 uS/(cm g). Analyzing the function of cell membrane selective semi-permeability by seed conductivity change and revealing the mechanism of seed viability enhancement by high voltage electric field polarisation treatment; In the seed germination test, compared with the control group, seed germination potential increased by 9.09%, germination rate increased by 20.45%, germination index increased by 3.49, and vigor index increased by 41.66 under high-voltage electrostatic polarisation treatment, and all vigor indexes were significantly improved. The results of this study can provide a basis for the selection of processes and parameters for subsequent high-voltage electric field polarisation treatment of crop seeds.

Embeddable Chloride Sensor for Monitoring Chloride Penetration into Cement Mortar.

A composite solid chloride sensor consisting of two single sensors, i.e., Ag/AgCl working electrode and Mn/MnO2 reference electrode, was developed. The Ag/AgCl electrode was prepared by the anodic polarization method, while the Mn/MnO2 reference electrode was prepared using the powder compaction technique. Then, the electrochemical performances such as stability, reproducibility, and sensitivity of the composite and single sensors were investigated in a saturated Ca(OH)2 solution and mortar specimen. A current density of 0.5 mA/cm2 and polarization time of 2.5 h were the optimal preparation parameters of the Ag/AgCl selective electrode. The Ag/AgCl selective electrode showed a linear potential response with the logarithm of chloride ion content in solution and had good stability, reproducibility, and anti-polarization performances. In addition, the Mn/MnO2 electrode exhibited potential stability after being activated in an alkaline solution for 60 days. The composite sensor demonstrated exceptional sensitivity to the Cl- content, boasting a slope of approximately 51.1 mV/decade, and showcased excellent stability in both solution and mortar specimens. In every measurement, the time needed for the potential of a composite sensor to become stable was less than 30 s. The sensor enables non-destructive in situ monitoring of the chloride ion content in cement mortar, thus realizing early warning of deterioration of reinforcement and guaranteeing long service life of the structure.

A novel hybrid method for calculating the fetal heart rate from the non-invasive abdominal Electrocardiogram signal

Continuous monitoring of fetal health requires the accurate calculation of the Fetal Heart Rate (FHR) by efficiently isolating fetal Electrocardiogram (fECG) from non-invasive abdominal Electrocardiogram (aECG). There are numerous solutions proposed for this problem, having its own restrictions. This paper introduces a novel three-stage hybrid adaptive approach for fECG extraction and FHR determination from aECG. The proposed framework is an amalgamation of independent component analysis (ICA), adaptive exponential functional link network (AEFLN), and novel wavelet thresholding (NWT). The proposed work aims to determine the best quality fetal R-peaks for calculating fetal heart rate (FHR). ICA is a blind source separation technique that uses all the information from the multichannel inputs to determine the maternal Electrocardiogram (mECG) and enhanced aECG. In the next stage, a non-linear adaptive filter, AEFLN, is used for the extraction of fECG. This approach requires no additional algorithm for polarity reversal and time alignment before AEFLN. At last, NWT determines the fetal R-peak envelopes from the residual fECG. The R-peak envelopes are used to analyze FHR, and its accuracy was accessed using the FHR trace. So far, FastICA-AEFLN-NWT has not been used as a hybrid method for fECG extraction and fetal R-peak detection. The algorithm’s effectiveness was tested on both real databases from Daisy and Physionet and synthetic databases from Physionet. The proposed hybrid method attains 95.29 % of sensitivity (SE), 96.68 % of Positive Predictive Value (PPV), 95.92 % of F1 score, and FHR measurement (FHRmeas) is 29.72 bpm2. The proposed methodology outperforms the state-of-art methods in fECG extraction.