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Energy conversion between the fields and the particles occurs through various physical processes within space environments. Magnetic reconnection stands out as one such process capable of rapidly and massively releasing energy. The high‐speed outflow jets produced by reconnection can induce turbulence characterized by intermittent structures. In this study, we investigate the impact of guide field on the energy conversion associated with the magnetic topologies within these structures during reconnection. Utilizing both particle‐in‐cell simulations and observations from the Magnetospheric Multiscale mission, our findings suggest that a larger guide field present during reconnection leads to increased energy conversion as well as the generation of O‐type topology structures within the turbulent outflow. Our results provide significant evidence on the relationships between energy conversion and magnetic topologies within turbulent outflow of reconnection and the guide field conditions. Plain Language Summary: In space environments, various physical processes involve the conversion of energy between magnetic fields and particles. One such process is magnetic reconnection, which can rapidly release a large amount of energy. During magnetic reconnection, high‐speed outflow jets are generated, leading to the formation of turbulent structures. In our study, we investigate how the presence of a guide field affects the energy conversion process and the resulting magnetic topologies within these turbulent structures during reconnection events. Using both particle‐in‐cell simulations and observations from the Magnetospheric Multiscale mission, we explore the impact of guide fields on energy conversion and magnetic topologies. Our findings indicate that a larger guide field present during reconnection leads to increased energy conversion and the generation of specific magnetic topology structures known as O‐type topologies within the turbulent outflow. These results provide significant insights into the complex relationships between energy conversion processes, magnetic topologies, and guide field conditions during magnetic reconnection events in space. Understanding these relationships is crucial for advancing our knowledge of fundamental physical processes occurring in space environments. Key Points: Magnetic topology in the turbulent reconnection outflow is investigated through both Magnetospheric Multiscale (MMS) observations and particle‐in‐cell (PIC) simulationsA larger guide field can promote the generation of O‐type topology in the turbulent outflow of the reconnectionHigher energy conversion is contributed by those O‐type topologies in the presence of a larger guide field [ABSTRACT FROM AUTHOR]

While Mars lacks a global intrinsic magnetic field, it does exhibit crustal magnetic anomalies (mostly in its Southern Hemisphere). These crustal magnetic anomalies directly interact with solar wind, which forms a mini‐magnetosphere and a region denoted the mini‐magnetopause. Using magnetic field and plasma measurements from the Mars Atmosphere and Volatile Evolution, we report a novel case of magnetic reconnection at the Martian mini‐magnetopause. In this process, protons and oxygen ions from the Martian atmosphere were accelerated during reconnection and likely escaped along the outflow direction. Magnetic reconnection may occur between the interplanetary magnetic field and crustal magnetic fields at the Martian mini‐magnetopause, which contributes to planetary ion escape, solar wind entering the mini‐magnetosphere and the evolution of magnetic topology in the dayside Martian mini‐magnetosphere. Plain Language Summary: While Mars lacks a global intrinsic magnetic field, it does exhibit crustal magnetic anomalies. The solar wind from the sun accompanied by interplanetary magnetic field (IMF) directly interacts with this crustal magnetic field, similar to what occurs on Earth, albeit at a smaller scale. The boundary between the crustal field on Mars and the IMF is called the mini‐magnetopause. Magnetic reconnection is a fundamental process in astrophysical and space plasmas that can change the topology of magnetic field and effectively convert magnetic energy into thermal and kinetic energy. Using magnetic field and plasma measurements from the Mars Atmosphere and Volatile Evolution missions, we report direction observations of magnetic reconnection at the Martian mini‐magnetopause. Through magnetic reconnection at the mini‐magnetopause, the IMF reconnects with the magnetic field from the crustal field, forming new magnetic field lines that channel solar wind to enter the Martian atmosphere and planetary plasmas to escape. Key Points: Magnetic reconnection at the Martian mini‐magnetopause is reported for the first timeProton and oxygen ions from the mini‐magnetosphere are accelerated during magnetic reconnectionMagnetic reconnection at the mini‐magnetopause could cause solar wind to enter the mini‐magnetosphere [ABSTRACT FROM AUTHOR]

Using high‐resolution data from the Magnetospheric Multiscale mission, an electron‐only reconnection current sheet is found between two successive dipolarization fronts (DFs). The electron‐only reconnection occurs between the northward component of the magnetic field of the flux pileup region (FPR) of the first DF (DF1) and the southward component of the magnetic dip of the second DF (DF2). The faster DF2 compresses the FPR of DF1, which constitutes an anti‐parallel topology and reduces the thickness of the current sheet. Further analysis shows that the current sheet is unstable to the electron tearing instability, which may power the onset of the reconnection. Our results suggest that these two DFs may merge into one by the reconnection, which sheds light on the evolution of DFs during their earthward propagation. Plain Language Summary: Magnetic reconnection, releasing magnetic energy and energizing plasmas, are believed to be responsible for the explosive phenomena in space. Though reconnection has been investigated for decades, the onset of reconnection is elusive. Dipolarization fronts (DFs), important carriers in the transportation of mass, magnetic flux, and energy in the magnetotail, can be generated by reconnections and will integrate into the geomagnetic field at last. The generation of DFs and dynamics at DFs are thoroughly probed by simulations and observations. However, the evolution of DFs during their earthward propagation is rarely inspected. In this work, we present an observation of an electron‐only reconnection between two successive DFs. The latter DF compresses the former DF and reduces the thickness of the current sheet between them. Inside the reconnection current sheet, electron tearing instability is unstable, which may power the reconnection. By reconnection, these two DFs may merge. Our observations can improve our understanding of the evolution of DFs in the magnetotail. Key Points: An electron‐only reconnection current sheet is found between two dipolarization frontsThe current sheet is unstable to the electron tearing instabilityDF2 compresses DF1 and thins the current sheet, which may initiate electron tearing instability and trigger the reconnection [ABSTRACT FROM AUTHOR]

Identifying how different wave modes interaction with each other is an important topic in space physics. Using measurements from the Magnetospheric Multiscale (MMS) mission, we report an event in the Earth's magnetosheath where ultra‐low‐frequency (ULF) waves, whistler waves, and quasi‐electrostatic whistler harmonics were observed simultaneously. Specifically, our analyses show that the parallel components of ULF waves modulate the electron butterfly distributions which provide the free energy to the excitation of the observed whistler waves. Meanwhile, quasi‐electrostatic waves sharing frequencies that are nearly integral multiples of the frequency of the observed whistlers are identified as nonlinear harmonics of whistler waves. The close correlations between the whistler waves and the electric field harmonics, as well as the high bicoherence indexes within the frequency ranges of the whistlers and harmonics, suggest the significant nonlinear couplings between the whistler waves and quasi‐electrostatic whistler harmonics. Our work provides new insights to the interactions between waves at different frequency bands. Key Points: Ultra‐low‐frequency (ULF) waves, whistler waves, and quasi‐electrostatic whistler harmonics are observed simultaneously in the magnetosheath plasmaULF waves modulate the electron butterfly shaped distributions which provide free energy for the excitation of the observed whistler wavesQuasi‐electrostatic waves are identified as the whistler harmonics, and may be generated by the wave‐wave nonlinear coupling [ABSTRACT FROM AUTHOR]

Heavy particles are extensively detected in the space environment, especially in the solar wind and interplanetary magnetosphere. Various physical processes can be affected by the physical dynamics of heavy particles. One of the processes is magnetic reconnection, which converts the energy from the magnetic field to the particles. In the present study, we investigate the impact of heavy particles with increasing mass (i.e., mass-loading effect) on energy conversion rate during magnetic reconnection. The declined reconnection rate and energy conversion rates by this effect are captured as reported previously. After considering three major regions in reconnection, it reveals that the mass-loading effect decreases more energy conversion rate of positive species at the separatrix, affects the heavier species less in the inner electron diffusion region (EDR), and propels the formation of a non-zero electric field at reconnection front (RF). Our results provide a more comprehensive understanding of the magnetic reconnection with complicated plasma components. [ABSTRACT FROM AUTHOR]

Dipolarization fronts (DFs) are widely believed to host energy conversion processes. However, which mechanism is responsible for the energy conversion is still obscure. Using data from the Magnetospheric Multiscale mission, a current sheet is observed at a DF. This current sheet is caused by interchange instability bending the edge of the DF. Inside the current sheet, Hall electromagnetic field, super Alfvénic electron jets, demagnetization of ions and electrons, strong energy conversion, and steady ion flow and temperature are observed, indicating an electron‐only reconnection at the DF. The duskward plasma flow, which may be deflected by the DF, compresses the bent edges of the DF. As a result, the width of the current sheet between two adjacent bent edges of the DF reduces, and then reconnection begins. Our observations give direct evidence that magnetic reconnection results in energy conversion at a DF. Plain Language Summary: Magnetic reconnection is an explosive phenomenon in space, which can rapidly convert energy from magnetic field to particles. Dipolarization fronts are essential carriers of mass and energy from the magnetotail to the Earth. Strong energy conversion, considered to be even more significant than magnetic reconnection, is usually observed at dipolarization fronts. However, the specific mechanism responsible for the energy conversion at a dipolarization front is elusive. Using data from the Magnetospheric Multiscale mission, we present direct evidence of magnetic reconnection at a dipolarization front, leading to strong energy conversion. The reconnection occurs in the current sheet at the dipolarization front. The duskward diverted flow compresses the bent dipolarization front induced by interchange instability, resulting in reconnection. Key Points: A current sheet with strong energy conversion is found at a DFThe strong energy conversion at this DF is mainly caused by the magnetic reconnectionThe duskward diverted flow compresses the bent DF caused by interchange instability, leading to the reconnection [ABSTRACT FROM AUTHOR]

Electron vortices are usually embedded within different magnetic structures in space plasmas. The effects, including the nonideal electric field, energy dissipation and magnetic field, of electron vortices on these magnetic structures are still unclear. Utilizing the unprecedented high‐resolution data from the Magnetospheric Multiscale mission in the terrestrial magnetosheath, we statistically investigate these effects on magnetic structures. Both nonideal electric fields and energy dissipation have no obvious correlations with the scales of electron vortices. However, compared to the scales, stronger correlations are found between the vorticities of electron vortices and nonideal electric fields, and energy dissipation, respectively. Most of electron vortices have positive contributions to magnetic fields of magnetic structures, such as strengthening the decrease (or increase) of Bt for current sheets and magnetic holes (or flux ropes and magnetic peaks). Our results reveal that the electron vortices play an important role in the evolution of magnetic structures. Plain Language Summary: The magnetosheath exhibits various dynamical features such as heating and compression of the plasma, kinetic instabilities, particle beams and kinetic structures due to the highly dynamical environment in near‐Earth space. The electron vortices as the structure that manifests the in suit observations, including bipolar variations of electron velocity and large electron vorticity, have been revealed widely in the magnetosheath. However, the specific effects of electron vortices embedded within the magnetic structures on these magnetic structures are still unknown, especially in a statistical view. Thanks to the unprecedented high‐time resolution data of the Magnetospheric Multiscale mission in the magnetosheath, we investigated the effects, including the nonideal electric fields, energy dissipation and magnetic fields, of electron vortices on these magnetic structures. We find that the nonideal electric fields, energy dissipation inside the electron vortices is more significant than outside for most of magnetic structures, and more than half of electron vortices have positive effects on generating the measured magnetic field of these magnetic structures, which is helpful for understanding the subsequent evolution and interaction between them. Key Points: The effects of nonideal electric field, energy dissipation and magnetic field of electron vortices on magnetic structures have been studiedThe nonideal electric fields and energy dissipation are more correlated with the vorticities of electron vortices compared to their scalesMost of electron vortices have positive contributions to magnetic fields of magnetic structures [ABSTRACT FROM AUTHOR]

Magnetic reconnection is the physical process that converts the energy from the fields to the plasmas in space, astrophysical and laboratory plasmas. The Reconnection front (RF) is the structure generated in the reconnection outflow region and participates in the energy release budget. Here, we first report a novel crater structure of magnetic field behind the RF, which is well supported by both the in‐situ observations from the Magnetospheric Multiscale mission and kinetic particle‐in‐cell simulations. The theoretical explanations from the simulations suggests that the formation of the crater structure is possibly due to that high‐speed outflow electron jet from inner electron diffusion region constantly strikes the RF. From another perspective, the crater structure is the continuous impact of the electron jet. Our results can establish a new understanding of the RF and energy conversion during magnetic reconnection. Plain Language Summary: Magnetic reconnection is a natural process in space environments, astrophysical settings, and laboratories, where energy from magnetic fields is transformed into the energy of various particles. One crucial structure in this process is called the reconnection front (RF), which plays a big role in how energy is released. In our study, we have discovered something interesting: a unique crater‐like structure behind the RF. We found evidence for this in observations from the Magnetospheric Multiscale mission and computer simulations that study the behavior of particles in magnetic reconnection. Our simulations suggest that this crater shape happens because electrons have the high‐speed outflow and form current jets. It is like the electrons poured out from the inner electron diffusion region, hitting a speed bump. Another way to think about it is that this crater is formed by the continuous impact of fast‐outflowing electron jets. Understanding this crater structure helps us better grasp how the RF works and how energy changes during magnetic reconnection. Our research finds and tries to explain a new piece of the puzzle in understanding the mysteries of space and plasmas in the magnetic reconnection process. Key Points: A novel crater structure is first verified behind the Reconnection front (RF) by both Magnetospheric Multiscale observations and particle‐in‐cell simulationsThe formation of the crater structure appears to be associated with the high‐speed electron jets from inner electron diffusion regionA possible scenario that electron outflow constantly strikes the RF and then causes the formation of the crater structure [ABSTRACT FROM AUTHOR]

Magnetic reconnection is a fundamental physical process of rapidly converting magnetic energy into particles. The electron diffusion region (EDR) is the crucial region during magnetic reconnection. The outer EDR, which also plays a crucial role in magnetic reconnection, is responsible for energy conversion. In the outer EDR, the electrons are decelerated and return the energy to the magnetic field on the pileup region behind the reconnection front. In the present study, we used the fully kinetic particle‐in‐cell simulation and revealed that part of decelerated electrons in the outer EDR could even move back to the inner EDR. This phenomenon is caused by the dominant contribution from the magnetic tension force, and it suggests a magnetic Marangoni effect in space plasma, similar to the Marangoni effect in fluids. Our results potentially propose a brand‐new physical process and a novel mechanism in the EDR during magnetic reconnection. Plain Language Summary: Plasma's energy can be changed through various approaches in the universe, and magnetic reconnection is one of those approaches to convert energy from the magnetic field to the plasma. In the reconnection site, the inner electron diffusion region (EDR) is an essential area where the energy is released, and the electron's energy is enhanced significantly. Meanwhile, in the outer EDR, the electrons are decelerated by the electric field, thus their energy decreases. However, part of those electrons can move backward to the inner EDR, and how this phenomenon comes up has no further investigation. In this study, we use numerical simulations to reveal the possible mechanism of this kind of electron's motion. It is found that the electron deceleration is caused by the magnetic tensor force. The electrons with specific conditions have the possibility to move backward. Those backflow electrons have a second chance to be accelerated again in the inner EDR. Such electron motion in plasma physics is not a kind of gyro movement but might indicate a so‐called magnetic Marangoni effect similar to the Marangoni effect in fluid physics. Our findings propose a novel mechanism associated with electron acceleration in the EDR during magnetic reconnection. Key Points: The magnetic tension force causes the deceleration of the electrons in the outer electron diffusion region (EDR) during magnetic reconnectionPartial electrons are decelerated and even move back to the inner EDR, and they are accelerated again and attain higher energyThe electron backflow motion in the outer EDR indicates a magnetic Marangoni effect in space plasma [ABSTRACT FROM AUTHOR]

In Saturn's magnetosphere, the plasma temperature increases with radial distance, requiring a heating mechanism to counteract the adiabatic cooling effect of expanding plasma. To explore potential heating source, we perform a statistical study about intermittent structures and intermittent heating in Saturn's magnetosphere based on the observations from the Cassini spacecraft. Partial Variance of Increments (PVI) technique is used to measure the intermittency of magnetic field and identify the intermittent structures. It is found that the electron temperature has a rising trend as the increase of magnetic field intermittency, implying the occurrence of electron heating in the intermittent structures. Additionally, the turbulence heating rate also exhibits an increasing trend as the increase of probability density of intermittent structures. Our results evidence the effect of intermittent heating in the Saturn's magnetosphere, and suggest that intermittent structures with high magnetic field intermittency play an important role in turbulence heating. Plain Language Summary: In Saturn's magnetosphere, the plasma temperature increases with radial distance, requiring a heating mechanism to counteract the adiabatic cooling effect of expanding plasma. Intermittent structure, which has been widely investigated in solar wind turbulence to explain the solar wind plasma heating, have never been considered in Saturn's magnetosphere. In this work, we investigate the intermittent structures and intermittent heating in Saturn's magnetosphere based on the observations from the Cassini spacecraft. We identify a positive correlation between electron temperature and magnetic field intermittency, as well as a positive correlation between turbulence heating rate and the probability density of intermittent structures. These results suggest that intermittent structures contribute to turbulent heating in Saturn's magnetosphere. Key Points: Intermittent structures are identified in Saturn's magnetosphere based on partial variance of increment techniqueElectron temperature has a rising trend as the intermittency increases, indicating the occurrence of intermittent electron heatingTurbulence heating rate increases as intermittent density rises, implying a contribution of intermittent structure to turbulence heating [ABSTRACT FROM AUTHOR]

With high‐resolution data from Magnetospheric Multiscale (MMS) mission, an ion‐scale flux rope (FR) with a heavily tilted axis is observed in the tailward outflow of a magnetic reconnection in the terrestrial magnetotail. Combined with the field‐aligned electron distribution and positions of MMS when the X‐line and FR are observed, the tilted axis is inferred to be caused by the extension of the X‐line in the dawn‐dusk direction. J · E′ is negative and electrons are losing energy in the FR. An ion‐scale electron vortex embedded in the plane perpendicular to the axis is observed inside FR. The induced magnetic field generated by the electron vortex has the same direction as the axial component, which can contribute to the axial component and increase the magnetic flux of the FR. Such electron vortex FRs may be an essential carrier of magnetic flux from near‐Earth X‐line to distant X‐line or interplanetary space. Plain Language Summary: Magnetic reconnection is an efficient energy and magnetic flux release process in the magnetotail. It is well known that dipolarization front is an important carrier of magnetic flux to Earth. However, how the magnetic flux transports at the tailward side is rarely concerned. In this work, we present an observation of an electron vortex flux rope as a new possible candidate. The embedded electron vortex generates an induced magnetic field with the same direction as the axial component of the flux rope, which is self‐consistent and can contribute to the enhancement of the magnetic flux carried by the flux rope by converting energy from electrons to the magnetic field. Our observations can contribute to understand the dynamics of the magnetotail. Key Points: An ion‐scale flux rope with an electron vortex embedded is observed in the tailward outflow of a magnetic reconnection eventThe tilted axis of the flux rope is due to the extension of the X‐line in the dawn‐dusk directionThe electron vortex flux rope may be an essential carrier of magnetic flux to distant tail or interplanetary space [ABSTRACT FROM AUTHOR]

The Kolmogorov scaling in the inertial range of scales is a distinct characteristic of fully developed turbulence, and studying it offers valuable insights into the evolution of turbulence. In this work, we perform a statistical survey of the power spectra with the Kolmogorov scaling in Saturn's magnetosphere using Cassini measurements. Two cases study show that both magnetic‐field and electron density spectra exhibit f−5/3 at the MHD scales. The statistical analysis reveals a wide‐ranging and abundant presence of Kolmogorov spectra throughout magnetosphere, observed across all local times. Interestingly, the occurrence rate of these Kolmogorov‐like events within Saturn's magnetosphere surpasses that observed in the planetary magnetosheath. The measurements of magnetic compressibility for the Kolmogorov‐like events show the dominance of incompressible Alfvénic turbulence (44.64%) with respect to magnetosonic‐like one (6.94%). In addition, the source and evolution of the turbulent fluctuations are further discussed. Plain Language Summary: Turbulence is ubiquitous in space and astrophysical plasmas, such as the solar wind, planetary magnetospheres, and the interstellar medium. Plasma turbulence has been widely studied in the solar wind and planetary magnetosheaths, but much less in the planetary magnetospheres. In the solar wind, power spectral density of the magnetic field fluctuations generally follows the so‐called Kolmogorov spectrum f−5/3 at the magnetohydrodynamic (MHD) scales, which suggests a fully developed turbulent state. In this study, we have discovered the widespread presence of Kolmogorov spectra in the Saturn's magnetosphere. The spatial distribution and nature of turbulent fluctuation for the Kolmogorov‐like events are also investigated in detail. Key Points: Magnetic field and electron density spectra have Kolmogorov scaling of f−5/3 at MHD scales in Saturn's magnetosphereThe spatial distribution of the Kolmogorov spectra within Saturn's magnetosphere reveals the extensive occurrence of Kolmogorov‐like eventsThe fluctuations for Kolmogorov‐like events are dominated by Alfvénic modes (44.64%) with respect to magnetosonic‐like one (6.94%) [ABSTRACT FROM AUTHOR]

Intense electromagnetic energy conversion and local magnetic flux transport occur at reconnection fronts (RFs) formed by magnetic reconnection. Tailward RFs (TRFs), characterized by sharply enhanced negative magnetic field normal components accompanied by tailward plasma flows, are the tailward propagating dipolarization fronts in the Earth's magnetotail. So far RFs and TRFs are observed merely at magnetized planets. Using data from Mars Atmosphere and Volatile EvolutioN, we report, for the first time, the observations of TRF embedded in a current sheet (possibly diffusion region of magnetic reconnection) in the Martian magnetotail. At the TRF, O+ and O2+ are accelerated in tailward direction; behind the TRF, the perpendicular electron fluxes enhance at the energy of 251–905 eV, which should be caused by betatron acceleration. The energized plasmas indicate that the electromagnetic energy converts to plasma kinetic energy around the TRF. Our observations suggest that RFs could occur in the planetary magnetotail without the global intrinsic dipole magnetic field. Plain Language Summary: Magnetic reconnection is a process that the anti‐parallel magnetic field lines break and reconnect, accompanied by explosive energy conversion. Without a global dipole magnetic field, Mars has interesting flexible magnetic fields in the magnetotail, which can be varied corresponding to the upstream interplanetary magnetic field. Magnetic reconnection occurs during the interplanetary magnetic field and Martian solar‐wind‐induced magnetosphere. Tailward reconnection fronts, characterized by sharply enhanced negative magnetic field normal components usually accompanied by tailward plasma flows, are generally formed by magnetic reconnection. Intense electromagnetic energy conversion occurs at reconnection fronts, consistent with local magnetic flux transport and global magnetotail flux reduction in the magnetotail. Utilizing measurements from the Mars Atmosphere and Volatile EvolutioN orbiter, for the first time we report the observations of tailward reconnection fronts in the near‐Mars magnetotail, which is unexpected for a planet without an intrinsic dipole magnetic field. Besides, ion acceleration and electron acceleration are found around the tailward reconnection fronts. Our work offers a new perspective and shows the importance of magnetic reconnection on the evolution of the near‐Mars magnetotail. Key Points: A tailward reconnection front is observed in the near‐Mars magnetotail for the first timeHeavy ion acceleration and electron acceleration are detected around the tailward reconnection frontReconnection fronts could occur in the planetary magnetotail without the global intrinsic dipole magnetic field [ABSTRACT FROM AUTHOR]

The topology of the magnetic and velocity fields at the kinetic scales are investigated in the context of nearly incompressible magnetosheath plasma turbulence. Using the unprecedented high‐resolution data from the Magnetospheric MultiScale mission, the joint probability distribution functions of geometrical invariants characterizing the magnetic and velocity fields gradient tensor at the kinetic scales are computed. The topological features of the magnetic and velocity field gradient tensors and their symmetric component tensors present axisymmetric distribution patterns, indicating that the structure of the plasma turbulence at the kinetic scales are different from those in hydrodynamic and magnetohydrodynamic turbulence. Moreover, a strong correlation between the straining and rotational parts of the magnetic and velocity field gradient tensors was found, which manifests the dominance of sheet‐like structures at the kinetic‐scales dissipation in incompressible plasma turbulence. Plain Language Summary: The terrestrial magnetosheath provides an excellent laboratory to study space plasma turbulence. Thanks to the unprecedented high time resolution data of the Magnetospheric Multiscale mission, the kinetic‐scales structures and dynamic of incompressible magnetosheath plasma turbulence can be investigated. By means of a universal topological classification method in fluid dynamics area, we construct the topological features of both magnetic and velocity field in incompressible plasma turbulence at dissipation scales. Our results show that the distribution of velocity‐field topological structures is different from the other turbulence system, such as hydrodynamic and magnetohydrodynamic turbulence. In addition, we verify that the sheet‐like structures dominate the kinetic‐scales dissipation in the incompressible plasma turbulence. Key Points: The kinetic‐scales topological features in incompressible magnetosheath plasma turbulence are investigatedDistribution patterns different from hydrodynamic and magnetohydrodynamic turbulence of velocity‐field topological characteristics are identifiedSheet‐like structures dominate dissipation‐scale dynamics in the incompressible plasma turbulence [ABSTRACT FROM AUTHOR]

Magnetic reconnection can efficiently heat and accelerate the electrons through various approaches and mechanisms. The electron diffusion region (EDR), especially the inner EDR, is one of the energization areas for the electrons during the reconnection. How the electrons' energy changes when passing the inner EDR is not well understood. In this study, we investigate the electron energy change from the individual perspective using the full kinetic particle-in-cell simulation. It is revealed that the electron energy gain rate is related to both traveling time and path in the inner EDR. The energy from the magnetic field tends to be allocated to the electron perpendicular part and the random thermal part. Our results promote the understanding of the function of the inner EDR during magnetic reconnection. [ABSTRACT FROM AUTHOR]

The small‐scale magnetic hole (SSMH), characterized by magnetic field depression, is a structure with the size in the order of proton gyro‐radius. SSMHs near the Earth or other planets have been widely observed in recent years. However, SSMHs in the solar wind near the Sun are rarely investigated due to mission constraints. In the present study, SSMHs in the pristine solar wind within a wide heliocentric distance range are analyzed based on the Parker Solar Probe (PSP) Mission measurements. A total of 2,416 SSMHs are successfully identified during the orbits of PSP from 2nd October, 2018, to 31st December, 2020, with an average occurrence rate of ∼5.8 events/day. The occurrence rate of SSMHs decreases from ∼29.5 to ∼0.6 events/day as the heliocentric distance R increases. The spatial scale of these SSMHs obeys a bi‐log‐normal distribution, with the median scale L ∼ 137 km (∼6 ρp, proton gyro‐radius). As interplanetary magnetic field Bave increases or R decreases, the upper limit of the spatial scale L corresponding to each bin extends to a larger value. The L corresponding to the maximum occurrence rate also increases when Bave increases and R decreases. Besides, the SSMHs tend to occur more frequently in the solar wind environment with weak Bave and high thermal pressure Pt. Our results shed light on the characteristics and the origin of SSMHs in the pristine solar wind. Plain Language Summary: Small‐Scale Magnetic Hole (SSMH) is a common structure in the universe, characterized by the magnetic field depression in a short time period, with the size in the order of proton gyro‐radius. The possible source region of SSMH has been debated a lot but cannot be researched carefully due to the limitation of the satellite mission in the solar wind. Using the in‐situ data from the Parker Solar Probe mission, which covers the region near the Sun previously unexplored, this statistical study focuses on SSMHs in the pristine solar wind within a wide range of heliocentric distances. The results show that the occurrence rate decreases with the increasing distance. SSMHs prefer to occur in a weak magnetic field with high thermal pressure in the solar wind. The maximum size of SSMHs increases as the magnetic field increases and the heliocentric distance decreases. The results on the properties of SSMHs and their occurrence rate will shed light on the origin of SSMHs in the pristine solar wind. Key Points: The occurrence rate of SSMHs decreases as moving away from the Sun, from ∼29.5 events/day to ∼0.6 events/dayUpper limit of L extends a little to larger value when Bave increases and R decreases, as well as L corresponding to the max occurrence rateSSMHs prefer to occur in the solar wind environment with a weak interplanetary magnetic field and high thermal pressure [ABSTRACT FROM AUTHOR]

Magnetic reconnection is a universal phenomenon existing in the space. Energy conversion is one of the essential parts of reconnection discussed for decades. Positive energy conversion (J·E′ > 0) is usually regarded as the sign of electron diffusion region (EDR), while the negative one (J·E′ < 0) turns out to gather in the outer EDR. Here we report the negative J·E′ appearing in the inflow edge of the inner EDR, based on Magnetospheric Multiscale mission observations and particle‐in‐cell simulations. Both observations and simulations verify that this negative J·E′ is mainly contributed from the electron pressure tensor term in generalized Ohm's law. The energy loss of electrons plays the dominant effect in the electron pressure tensor, and this energy decline is caused by the electric field which is induced by the decreasing magnetic field. Our results provide significant insights to expand the understanding of the reconnection regimes. Plain Language Summary: In interplanetary space and other space environments, magnetic reconnection can be detected through spacecraft observations. It affects the energy conversion between the fields and the plasmas. The positive energy conversion in the reconnection usually describes the process in that energy is transformed from the magnetic field to the particles. The negative one, however, represents the inverse form. With the help of satellite data, we find negative energy conversion in the inflow edge of the center site of magnetic reconnection (i.e., the inner electron diffusion region). We also perform kinetic simulations to verify the satellite observation results. These two results have well corresponded to a certain extent. We make further investigation on the simulation data to reveal the physical mechanism. It is found that electrons' energy has decreased in the inflow edge due to the electric field formed by the decreasing magnetic field in the inflow region. Such decline of the electrons' energy causes the change of electron pressure tensor. Our study may promote a more profound understanding of energy conversion during magnetic reconnection. Key Points: Negative energy conversion (J·E′ < 0) can appear in the inflow edge of the inner EDR during tail magnetic reconnectionBoth simulations and observations confirm that the negative energy conversion closely connects with the electron pressure tensor termThe electric field induced by the decreasing magnetic field causes the electron velocity decline and negative energy conversion [ABSTRACT FROM AUTHOR]

Kinetic‐size magnetic holes (KSMHs) can accelerate and heat the particles, resulting the energy dissipation in space plasmas. KSMHs in the terrestrial foreshock region are statistically investigated based on the Magnetospheric Multiscale data from October 2015 to December 2019. A total of 98 KSMHs are successfully selected, and most of them are accompanied by electron vortices. The fluxes of electrons at ∼90° of pitch angle enhance inside the magnetic holes, where the perpendicular and total electron temperature increase, and the parallel electron temperature slightly decreases inside these magnetic holes. Moreover, we reveal a novel phenomenon that a lot of the observed KSMHs are probably moving toward the Sun in the plasma flow frame. Such sunward propagating KSMHs are detected for the first time in the foreshock region. We propose that these observed KSMHs are probably generated in the foreshock region and then propagate to the Sun. Plain Language Summary: Magnetic hole, characterized by the significant decrease of magnetic strength, is usually observed in the planetary magnetosphere. Kinetic‐size magnetic holes (KSMHs) with the scale below ion gyroradius have attracted much interest in recent years. KSMHs can accelerate and heat the particles, resulting the energy dissipation in space plasmas. Based on the Magnetospheric Multiscale data, KSMHs in the terrestrial foreshock region are statistically investigated for the first time. We reveal some novel phenomenon for the observed KSMHs in the foreshock region. Key Points: We present the observational evidence of kinetic‐size magnetic holes (KSMHs) in the terrestrial foreshock regionA lot of the observed KSMHs are probably moving toward the Sun in the plasma flow frameThese observed KSMHs are probably generated in the foreshock region and then propagate toward the Sun [ABSTRACT FROM AUTHOR]

Utilizing data from the Magnetospheric Multiscale mission, the sub‐structures of the separatrix region during reconnection are investigated. A small current system in the separatrix region is embedded in the large Hall current system, which appears as a quadrupole current. This small current system has an opposite direction to the Hall current and cancels part of the Hall magnetic field. The formation of the quadrupole current is possibly related to the patchy parallel electric field. The electric field in the separatrix region can be divided into three sub‐layers according to the electron frozen‐in condition. En enhances in two outside sub‐layers, where the strong En is supported by the Hall term and electron pressure gradient term, and the nearly zero En, separating the enhanced electric fields, is caused by a small flow and electron density gradient. Our observations imply complex dynamics in the separatrix region during magnetic reconnection. Plain Language Summary: Magnetic reconnection is an explosive energy conversion process that converts magnetic energy to particles. Meanwhile, the topology of the magnetic field is changed. Many phenomena in space are related to magnetic reconnection, like solar flares and aurora. The separatrix is the layer separating the plasmas not yet entered the reconnection process and those already processed by reconnection. The characteristics of plasmas are quite different at the two sides of the separatrix, which makes the separatrix dynamic. With high‐resolution data from the Magnetospheric Multiscale mission, we investigate the sub‐structures of the separatrix region in a reconnection event in the magnetotail. The quadrupole current and multi‐layer electric field are observed in the separatrix region. The quadrupole current is possibly related to the patchy parallel electric field. And the multi‐layers electric field are caused by the complex electron flow patterns. Our observations reveal the highly‐structured nature of the separatrix region and may help to improve our understanding of the reconnection process. Key Points: Quadrupole current and multi‐layer electric field are observed in the separatrix regionQuadrupole current is possibly related to the patchy parallel electric fieldMulti‐layer electric field are caused by complex electron flow patterns [ABSTRACT FROM AUTHOR]

Substorms are a fundamental phenomenon in planetary magnetospheric systems. Using Cassini measurements, we report a typical event in which four successive dipolarization fronts (DFs) were observed within 1 hour during the substorm in Saturn's magnetotail. The last three DFs caused a type of stepwise electron acceleration and generated energetic electrons. The pitch angle distributions of the electrons show evidence of the Fermi acceleration mechanism behind these DFs. Therefore, we infer the magnetotail dynamics process during Saturn's substorm: The stepwise acceleration by successive DFs powerfully accelerates the field‐aligned electrons and generates field‐aligned energetic electrons. These high‐energy electrons are injected into the inner magnetosphere and become an important trigger of Saturn's aurora. Our results show an efficient acceleration mechanism for the electrons caused by successive DFs and confirm an important source of energetic particles during the substorm in Saturn, and these findings improve our understanding of Saturn's substorm and magnetotail dynamics. Plain Language Summary: Substorms play a role in the energization and transport of plasmas in planetary magnetospheres. During substorms, what specific dynamic processes contribute to particle acceleration and transport remains an important question. In our work, using measurements from the Cassini spacecraft, we report a typical event in which four successive dipolarization fronts (DFs) were observed within 1 hour during the substorm in Saturn's magnetotail. The last three successive DFs cause energetic electrons by stepwise electron acceleration. The electron acceleration is possibly caused by the Fermi acceleration mechanism, which mainly enhances the electron velocity component parallel or antiparallel to the local magnetic field. Our study provides an explanation for the energetic particle injection source of Saturn's aurora and improves our understanding of Saturn's substorm and magnetotail dynamics. Key Points: Four successive dipolarization fronts (DFs) are identified in Saturn's magnetotail during one substormThree of the successive DFs cause a type of stepwise electron acceleration, generating energetic electronsAccording to the electron pitch‐angle distribution, the stepwise electron acceleration is identified as the Fermi acceleration mechanism [ABSTRACT FROM AUTHOR]

It is widely acknowledged that positive energy dissipation J ⋅ E′ from the fields to the plasmas occurs in the electron diffusion region (EDR) during magnetic reconnection. There also exists negative J ⋅ E′ in the outer EDR, but what causes such negative J ⋅ E′ is still unclear. In the present study, we applied 2.5‐D particle‐in‐cell simulation to investigate what causes the negative J ⋅ E′ in the outer EDR through generalized Ohm's law. It is found that the region of negative J ⋅ E′ expands in space with the evolution of magnetic reconnection, and the embodiment of negative J ⋅ E′ is dominated by the electron inertial term in the generalized Ohm's law due to the deceleration of the electrons in the outer EDR. This deceleration is caused by the opposite electric field compared with the ones in the inner EDR. And the opposite electric field is induced by the newly reconnected magnetic field lines in the outer EDR. Our results give a new perspective of energy transformation between the fields and the plasmas during magnetic reconnection. Plain Language Summary: Magnetic reconnection is a widespread important physical process that allows the rapid energy conversion of the magnetic field into the plasmas, resulting in the particle's acceleration/energization and the changing of magnetic field topology. Magnetic reconnection is a key mechanism responsible for Gamma ray bursts, solar flares, auroral substorm, fusion experiments, interstellar medium, astrophysical jets, galaxy clusters, etc. Previous studies of magnetic reconnection containing energy release mostly work on positive energy dissipation. However, there also exists a negative value, which means the energy of the particles is converted into magnetic energy, and what causes this negative energy dissipation is still unclear. In this study, we apply 2.5‐D particle‐in‐cell simulation to investigate the reason for this negative energy dissipation from the perspective of generalized Ohm's law in the outer electron diffusion region. It shows that this kind of negative value is concerned with the electron inertial term. The deceleration of the electrons in the outer electron diffusion region is the main contribution. Key Points: The negative J ⋅ E′ in the outer electron diffusion region (EDR) expands in space with the time evolutionThe embodiment of negative J ⋅ E′ is dominated by the electron inertial term due to the deceleration of the electrons in the outer EDRThis deceleration is caused by the opposite electric field induced by the newly reconnected magnetic field lines in the outer EDR [ABSTRACT FROM AUTHOR]

Based on the unprecedented high‐resolution data from the Magnetospheric Multiscale mission, we investigate the energy dissipation in turbulent reconnection outflow during turbulent magnetic reconnection in the terrestrial magnetotail. It is found that this reconnection outflow has plenty of intermittent structures at kinetic scales accompanied by abundant current filaments. Strong energy dissipation occurs in the intermittent structures with a high partial variance of increments index, and the regions with strong current filaments. Further analyses reveal that electron heating with the presence of increase in electron temperature occurs in the intermittent structures and the regions with strong currents. This electron heating is more significant in the component parallel to the magnetic field. Our observations demonstrate that intermittent dissipation at kinetic scales occurs in the turbulent reconnection outflow. Plain Language Summary: Magnetic reconnection is an essential physical process in space, astrophysical, and laboratory plasmas, and it can effectively convert magnetic energy into particle energy accompanied by the change of magnetic field topology in a short time period. It has already been confirmed that magnetic reconnection can produce turbulent reconnection outflows. How and where the energy dissipation takes place in reconnection outflows remains a remarkable open question until now. Thanks to the unprecedented high time resolution data of the Magnetospheric Multiscale mission, we investigate the energy dissipation in turbulent reconnection outflow in the terrestrial magnetotail. Our observations reveal that intermittent dissipation at kinetic scales with strong currents occurs in the turbulent reconnection outflow. Key Points: Intermittent structures at kinetic scales accompanied with strong current filaments are abundant in turbulent reconnection outflowsStrong energy dissipation and electron heating occur in the intermittent structures and the regions with strong current filamentsThere exists intermittent dissipation at kinetic scales in turbulent reconnection outflows [ABSTRACT FROM AUTHOR]

Plasma bubble, a low-entropy flux tube, is usually regarded as the bearer of plasma flux transport in the magnetotail. In this study, we perform a complete analysis of electron dynamics in a plasma bubble in the Earth's magnetotail based on the high time-resolution data from the Magnetospheric Multiscale (MMS) mission. An electron jet is observed at the center of this plasma bubble. Simultaneously, intense electric field and significant current density, as well as the strong energy dissipation are detected associated with this electron jet. The pitch angle distributions (PADs) of high-energy electrons exhibit different features at different substructures in this plasma bubble. In Region-1 and Region-3, pancake-type PAD is formed; the PAD becomes isotropic type in Region-2. The electrons pitch angle changes to field-aligned distribution in Region-4. All these changes of electron PADs in substructures can be interpreted mainly by the capture of magnetic mirror and betatron cooling. High-frequency waves, including whistler waves and electrostatic waves, are detected in several parts of the plasma bubble. The observations of abundant electron-scale phenomena or processes reveal that the electrons are very dynamic in the large-scale plasma bubble. [ABSTRACT FROM AUTHOR]

Dipolarization front (DF) is a sharp magnetic structure featuring the increase of Bz in the magnetotail. Various types of waves have been observed around the DF. However, in the magnetic dip ahead of the DF, very few waves have been reported so far. In this study, we report broadband high‐frequency electrostatic waves in the dip region by using high resolution data from the magnetospheric multiscale (MMS) mission. The frequency range of these electrostatic emissions is higher than electron cyclotron frequency but lower than electron plasma frequency. These high‐frequency waves are quasi‐parallel propagating, and their parallel components dominate. Simultaneously, the measured field‐aligned electron distribution function (EDF) has a positive slope (df/dv|| > 0). The kinetic theory dispersion relationship curve based on the measured EDF reveals that the positive slope is responsible for the generation of high‐frequency electrostatic wave in the magnetic dip ahead of the DF. Key Points: High‐frequency electrostatic waves are observed in the dip region ahead of the dipolarization frontThese high‐frequency waves are quasi‐parallel propagating, and their parallel components dominateLinear dispersion analysis proves that these waves are excited by the positive slope of the field‐aligned electron distribution function [ABSTRACT FROM AUTHOR]

Dipolarization front (DF), characterized by a sharp increase of the south‐north component of the magnetic field, is suggested to play an important role in transferring plasmas, magnetic fluxes, and energy in the planetary magnetosphere. Using the measurements from the Cassini spacecraft between January 1, 2005 and June 15, 2011, we successfully selected 96 DF events, and obtained the global spatial distribution of DFs in the Saturn's magnetosphere. For the first time, we found that DFs are distributed not only in the nightside magnetotail but also in the dayside magnetosphere. The dayside DF events are mainly located from X = 10 RS to X = 30 RS (RS is the Saturn's radius) while the nightside events have a wide range, up to X∼−50 RS. Moreover, the DFs are observed to be asymmetric in the south‐northern hemisphere: ∼70% of events in the northern hemisphere and ∼30% of events in the southern hemisphere, which is likely to be due to the asymmetric orbit coverage of the Cassini in south‐northern hemisphere. The occurrence of dayside DFs provides a strong evidence that the magnetic reconnection could also occur in the dayside of Saturn's magnetosphere. Thus, our results concerning the location and distribution of DFs are helpful for the study of the site of magnetic reconnection and energy transport/dissipation in Saturn's magnetosphere. Plain Language Summary: Saturn's magnetosphere is influenced by not only the solar wind, but more importantly the internal sources. Therefore, its magnetosphere would show different characteristics from terrestrial planets. Dipolarization front (DF), characterized by a sharp increase of the south‐north component of the magnetic field, is directly and closely related to magnetic reconnection, planetary substorm and planetary aurora, and can be a great medium for studying the magnetosphere's response to the solar wind and internal sources. In this work, using the measurements from the Cassini, we selected 96 DF events and obtained the global spatial distribution of DFs in the Saturn's magnetosphere. For the first time, we found that quite a big portion of DF events appear in the dayside magnetosphere. Therefore, we propose that the dynamics processes that generally occur at the magnetotail can extend to the whole magnetosphere in Saturn. Our work provides further evidence for the previous studies that the magnetic reconnection occurs in Saturn's dayside magnetodisc. Key Points: A complete global distribution is provided to show the location and local time of dipolarization fronts in Saturn's magnetosphereThere is a surprising large portion of dipolarization fronts observed at the dayside of Saturn's magnetosphereOur results support the existence of dayside magnetodisc reconnection in Saturn [ABSTRACT FROM AUTHOR]

We used nearly 4 years of data from the Mars Atmosphere and Volatile EvolutioN orbiter to map the distribution and motion of energetic O+ ions (2.3–30 keV) in the Martian environment. Our analysis reveals two typical features: a strong plume of energetic O+ ions in the +E hemisphere at dayside, driven by the convective electric field, and a less strong tailward gathering flow of energetic O+ ions in the –E hemisphere at nightside. Based on previous studies, this study reveals more details on energetic O+ ion escape: (a) velocities for energetic O+ ions between bow shock and induced magnetic boundary have much larger Y‐axis component, indicating that energetic O+ ions may not only escape along +Z‐axis but also slip away on the Y‐axis in MSE coordinates; (b) energetic O+ ions at low altitude in the –E hemisphere have little component along Y‐axis, and energetic O+ ions at nightside in the –E hemisphere "gather" along the tail and finally escape from the planet, driven by the convective electric field and the Martian current system. Comparing the fluxes and escape rates of energetic O+ at different distances away from the Sun and under different solar activities, we found that the heliocentric radial distance of Mars plays a more important role in ion escape than the solar activity level. Plain Language Summary: The answer to how does the water escape from unmagnetized planets like Mars is debated. Due to lack of an intrinsic global magnetic field, the Martian upper atmosphere can be easily eroded by the solar wind, which is an effective way for the water to escape after being ionized to H+ and O+. The motion of energetic O+ ions can be used as a probe of the escape of heavy ions. In present study, we report a global map of energetic O+ ions outflows for the first time using nearly 4 years of data from the Mars Atmosphere and Volatile EvolutioN orbiter. Our analysis reveals two typical features: a strong radial plume of energetic O+ ions in the northward dayside, driven by the convective electric field, and a less strong tailward gathering flow of energetic O+ ions in the southward nightside. In addition, we found that the heliocentric radial distance of Mars plays a more important role in ion escape than the solar activity level. These results are helpful to understand where and how the water escape from the unmagnetized planets to the space. Key Points: A global map of energetic O+ ions (from 2.3 to 30 keV) outflows is built using 4 years data from Mars Atmosphere and Volatile EvolutioNEnergetic O+ ions are able to slip away along Y‐MSE direction in the plume and "gather" along the tail in the −E hemisphereThe heliocentric radial distance of Mars plays a more important role in ion escape than the solar activity level [ABSTRACT FROM AUTHOR]

We perform a statistical analysis on current density, energy conversion, and electron acceleration in the primary flux ropes (PFRs) and the secondary flux ropes (SFRs) distinguished by out-ofplane electron current, respectively. It is found that current filaments are plentiful in both PFRs and SFRs. The closer to the center of the SFRs, the stronger the |J| is. The J•E' is intermittent in the PFRs. However, J•E' almost stays positive in the SFRs. The local adiabatic acceleration of the electrons in the PFRs and the SFRs are explored. Fermi and betatron acceleration are closely related to the adjacent magnetic field and bulk flow which can lead to the contraction/relaxation of the PFRs and SFRs and enhance/reduce the gradient of the magnetic field. The acceleration by the parallel electric field is significant in the SFRs. Our results can help to improve the understanding of the PFRs and SFRs and their roles in the magnetotail dynamics. Plain Language Summary Flux ropes, characterized by bipolar change of normal component of the magnetic field and enhancement of the core filed, are 3D magnetic structures. It is believed that flux ropes are dynamic and they usually play an important role in magnetic reconnection, such as dissipating energy and accelerating electrons. Flux ropes can be divided into primary flux ropes (PFRs) and secondary flux ropes (SFRs) according to different generation mechanisms. Though flux ropes have been investigated for decades, the statistical properties of the PFRs and the SFRs have not been obtained and compared. The commonalities and differences between PFRs and SFRs are ambiguous. Using the unprecedented high time resolution data of the Magnetospheric Multiscale (MMS) mission, we perform statistical analysis on current density, energy conversion, and electron acceleration in the PFRs and the SFRs, respectively. Our results may help to improve the understanding of the PFRs and SFRs and their roles in magnetotail dynamics. [ABSTRACT FROM AUTHOR]

We present an approach for compressing volumetric scalar fields using implicit neural representations. Our approach represents a scalar field as a learned function, wherein a neural network maps a point in the domain to an output scalar value. By setting the number of weights of the neural network to be smaller than the input size, we achieve compressed representations of scalar fields, thus framing compression as a type of function approximation. Combined with carefully quantizing network weights, we show that this approach yields highly compact representations that outperform state‐of‐the‐art volume compression approaches. The conceptual simplicity of our approach enables a number of benefits, such as support for time‐varying scalar fields, optimizing to preserve spatial gradients, and random‐access field evaluation. We study the impact of network design choices on compression performance, highlighting how simple network architectures are effective for a broad range of volumes. [ABSTRACT FROM AUTHOR]

We investigate spatial correlation functions (SCFs) at kinetic range in the terrestrial magnetosheath because of wide angular distributions of the magnetic field fluctuations and the high Signal‐to‐Noise‐Ratio. We employ four‐point measurements of magnetic fluctuations from the Cluster and MMS concerning a spatiotemporally varying background magnetic field to constitute the two‐dimensional (2‐D) SCFs between ion and electron scales. It is found that two populations exist in the 2‐D SCFs, with the minority elongated along the perpendicular coordinate (S⊥) and the majority of population elongated along the coordinate parallel to average magnetic field (S||). This kind of phenomenon indicates that the distribution of magnetosheath turbulence in the wavenumber space is dominantly transverse to the background magnetic field, simultaneously partly along the field (i.e., k⊥ >> k||). In addition, we find that magnetosheath turbulence is the dominance of shear Alfvénic‐like fluctuations, and is quasi‐monofractal intermittent turbulence at kinetic range for both the Cluster case and the MMS case, indicating that strong spatially anisotropic fluctuations may be universal in the magnetosheath. Our observations pose new challenges to the theoretical modeling of turbulence and dissipation at kinetic range in the collisionless magnetized plasma. Key Points: Two populations exist in the two‐dimensional SCFs at kinetic range in the magnetosheath turbulence.The major population elongated along the coordinate parallel to B0 and the minor one elongated along the perpendicular coordinate.Magnetosheath turbulence is the dominance of shear Alfvénic‐like fluctuations, and is multifractal intermittent turbulence at kinetic range. [ABSTRACT FROM AUTHOR]

Using four‐point measurements from the Magnetospheric Multiscale (MMS) mission, we identify whistler waves at the boundary of an ion scale magnetic hole, which should be locally excited rather than propagated from other regions. Based on the measured local plasma parameters, which include those for bidirectional electron beams with electron temperature anisotropy, the frequency range with the growth rate derived from kinetic theory is consistent with the observations, while the growth rate in the absence of such beams is negative; hence, the observed whistler waves are locally excited by the bidirectional electron beams with electron temperature anisotropy. The dispersion relation, derived from one‐dimensional particle‐in‐cell simulations that are conducted using the inputs of the bidirectional electron beams with electron temperature anisotropy, agrees well with the one from kinetic theory, which further supports this excitation mechanism. Our results shed light on a new excitation mechanism for whistler waves. Plain Language Summary: Whistler waves are nearly field‐aligned propagating and right‐hand polarized electromagnetic modes with the frequency between lower hybrid frequency and electron cyclotron frequency. Whistler waves are frequently and widely detected in the planetary magnetosphere and the interplanetary space and play an important role in the particle dynamics therein. For example, the electrons could be effectively accelerated by the electromagnetic whistler waves. Thanks to the unprecedented high time resolution and multipoint data from the Magnetospheric Multiscale (MMS) mission, the whistler waves are identified at the boundary of a magnetic hole in the magnetosheath. Based on the measured local plasma parameters including bidirectional electron beams with electron temperature anisotropy, both the linear theory based on kinetic plasma and one‐dimensional particle‐in‐cell (PIC) simulations confirm that the observed whistler waves are locally excited by the presence of bidirectional field‐aligned electron beams with electron temperature anisotropy for the first time. Our results shed new light on new excitation mechanism for whistler waves. Key Points: Whistler waves are identified at the boundary of a magnetic holeLinear theory and simulations confirm that whistler waves are excited by bidirectional electron beams with temperature anisotropyOur results shed new light on new excitation mechanism for whistler waves [ABSTRACT FROM AUTHOR]

Dipolarization front (DF), embedded in fast plasma flow, is a sharp structure with the increase of Bz in a short time and plays an important role in the energy dissipation and particle accelerations in the magnetotail. However, detailed physics at the small scales is still unclear in the DF due to the limitation of the previous mission. In the present study, an electron‐scale plateau in Bz is observed at the DF by Magnetospheric Multiscale (MMS) mission. By analyzing the velocity of the electrons, we find that the electron‐scale plateau is surrounded by a sub‐ion‐scale electron vortex, which is the first observation of electron vortex at the DF as far as we know. The magnetic field generated by the electron vortex cancels parts of the increase of Bz and causes the plateau. Strong asymmetric electric field and demagnetization of electrons and ions are observed at the boundary of the electron vortex. These results shed new light on that small‐scale structures can develop within the ion‐scale DF and affect the evolution and kinetic effects at the DF. Key Points: A sub‐ion‐scale electron vortex is observed at a dipolarization frontThe excited magnetic field of the electron vortex suppresses parts of the increase of Bz and causes the plateau at the dipolarization frontStrong asymmetric electric field and demagnetization of electrons and ions are observed at the boundary of the electron vortex [ABSTRACT FROM AUTHOR]

Magnetosonic waves, with the frequency between proton cyclotron frequency and lower hybrid frequency, mainly occur near the Earth's magnetic equatorial plane and play an important role in the magnetospheric dynamics. In this paper, we report unusual magnetosonic waves with nonlinear harmonics observed by Magnetospheric Multiscale mission in the magnetotail. These magnetosonic waves have multiband enhanced electromagnetic power spectral densities (Bw/B0 up to 1/45) with the frequency from below to above the lower hybrid frequency and are quasi‐perpendicular propagating and linearly polarized. The frequency of the fundamental band is much higher than the proton cyclotron frequency fci (i.e., ~35 fci). We identified these emissions as high‐frequency magnetosonic waves with nonlinear harmonics. These are the first observations of such high‐frequency magnetosonic waves with the frequencies of harmonics higher than the lower hybrid frequency in the Earth's magnetosphere to the best of our knowledge. Given the absence of ring distributions for the protons and the easy coupling between compressed mode and its electromagnetic term, we propose that these nonlinear harmonic structures of the observed magnetosonic waves are likely generated by the nonlinear wave‐wave coupling among electromagnetic terms of the fundamental and higher harmonic waves. Key Points: First observations of high‐frequency multiharmonic magnetosonic waves with the frequencies of harmonics higher than the lower hybrid frequency are observed in the Earth's magnetosphereSuch magnetosonic waves have nonlinear harmonicsNonlinear harmonics are likely to be generated by nonlinear wave‐wave coupling interaction [ABSTRACT FROM AUTHOR]

Using high‐resolution data of Magnetospheric Multiscale mission, we observed a gradual but periodical dipolarization process (DPs) in the Earth's magnetotail for the first time. These sub‐DPs, characterized by increase of Bz component and magnetic magnitude Bt, have a period of ~16 s. The electrons have a cigar distribution in the first three sub‐DPs but have a pancake distribution in the last sub‐DP, which excites two oppositely propagating whistler waves. At the trailing boundary of the last sub‐DP, Bz decreases sharply. Meanwhile, strong tailward and duskward plasma flow, intense current, ion and electron demagnetization, and positive energy conversion from the fields to the plasmas are observed at this boundary. By comparing the motion of this boundary with the plasma flow, we infer that the flow rebounds in longer period of the last DP and causes perpendicular electron acceleration. The periodical sub‐DPs and kinetic effects on the DP could improve our understanding of substorm and the magnetotail dynamics. Key Points: A gradual but periodical dipolarization process (DP) is observed in the magnetotail for the first timeDifferent electron distributions are observed in the different sub‐DPsDynamic process and fine structures in the last sub‐DP are analyzed [ABSTRACT FROM AUTHOR]

Aim: Anastomotic leakage (AL) is one of the most feared postoperative complications after anterior resection (AR) of rectal cancer. An adequate blood supply at the anastomotic site is regarded as a prerequisite for healing. We hypothesize that the Aortic Calcification Index (ACI) might reflect the severity of atherosclerosis in patients, and thereby be a risk factor for AL. Method: AL was investigated retrospectively according to the definition of the International Study Group of Rectal Cancer in 423 rectal cancer patients who underwent anterior rectal resection. The ACI was measured by preoperative abdominal CT scan. The cross‐section of the aorta was evenly divided into 12 sectors, the number of calcified sectors was counted as the calcification score of each slice. Lasso logistic regression and multivariate regression analysis were used to identify risk factors for AL. Results: The percentage of AL after AR was 7.8% (33/423); the mortality of patients who sustained a leak was 3.0% (1/33). Patients with a high ACI had a significantly higher percentage of AL than patients with low ACI (11.2% vs 5.6%, P = 0.04). Among patients with AL, a higher ACI was associated with greater severity of AL (the ACI of patients with grade A leakage, grade B leakage and grade C leakage was 0.5% ± 0.2%, 11.5% ± 9.2% and 24.2% ± 21.7%, respectively; P = 0.008). After risk adjustment, multivariate regression analysis showed that a higher ACI was an independent risk factor for AL (OR 2.391, P = 0.04). Conclusion: A high ACI might be an important prognostic factor for AL after AR for rectal cancer. Confirmatory studies are required. [ABSTRACT FROM AUTHOR]

Soil N2‐fixing bacterial communities (SNB) can enhance soil N availability and the invasiveness of invaders. Some invaders display different degrees of invasion across different climate regions. Given that bacterial communities may change with different climate regions, it is important to understand soil micro‐ecological mechanisms driving the successful invasion of invaders across different climate regions.This study performed cross‐site comparisons to comprehensively analyse effects of the invasive tree staghorn sumac (Rhus typhina L.) on the structure of SNB. In north China, we selected three sites within two sampling regions (a warm temperate region and a cold temperate region).Staghorn sumac invasion did not significantly affect soil physicochemical properties and the diversity and richness of SNB. LEfSe analysis showed that numerous SNB taxa changed significantly during staghorn sumac invasion. This may be attributed in part to the selective effects of allelochemicals released by staghorn sumac via leaf litter and/or root exudates. Consequently, staghorn sumac invasion may alter the structure, rather than the diversity and richness, of SNB to facilitate its invasion process by establishing a favourable soil microenvironment in the invaded habitats. The number of species and richness of SNB under staghorn sumac invasion were significantly lower in the warm temperate region than in the cold temperate region. A possible reason for the increased diversity and richness of SNB under staghorn sumac invasion in the cold temperate region may be because staghorn sumac in the cold temperate region can provide more nutrients into the soil sub‐ecosystem, presumably to support a higher diversity and richness of SNB via the nutritional requirements of SNB.The changed structure of SNB under staghorn sumac invasion, especially across different climate regions, may play an important role in its successful invasion across most regions of north China. [ABSTRACT FROM AUTHOR]

An ion‐scale flux rope (FR), embedded in a high‐speed electron flow (possibly an electron vortex), is investigated in the magnetotail using observations from the Magnetospheric Multiscale (MMS) spacecraft. Intense electric field and current and abundant waves are observed in the exterior and interior regions of the FR. Comparable parallel and perpendicular currents in the interior region imply that the FR has a non‐force‐free configuration. Electron demagnetization occurs in some subregions of the FR. It is surprising that strong dissipation (J × E' up to 2,000 pW/m3) occurs in the center of the FR without signatures of secondary reconnection or coalescence of two FRs, implying that FR may provide another important channel for energy dissipation in space plasmas. These features indicate that the observed FR is still highly dynamical, and hosts multiscale coupling processes, even though the FR has a very large scale and is far away from the reconnection site. Plain Language Summary: Flux ropes, 3‐D helical magnetic structures, in which magnetic field lines twist with each other, play an important role in the macroscopic and microscopic physical process during magnetic reconnection. Most of previous studies focused on the flux ropes in the reconnection region. However, some physical process inside macroscopic flux ropes far away from the reconnection site in the magnetotail is still unclear due to the lack of high time resolution data. In this letter, thanks to the unprecedented high time resolution data of the Magnetospheric Multiscale (MMS) mission, we report an ion‐scale flux rope and study its dynamics. Our observations demonstrate that the observed flux rope is still highly dynamical, and hosting multiscale coupling processes and strong energy dissipation, even though the flux rope has very large scale and is far away from the reconnection site. Key Points: An ion‐scale flux rope, embedded in possible electron vortex, is investigated in the magnetotail in detailsElectron demagnetization occurs in some subregions of the flux rope, and abundant waves are detected in the exterior and interior regionsStrong dissipation occurs in the flux rope, implying that flux rope provides another important channel for energy dissipation in space plasma [ABSTRACT FROM AUTHOR]

Humans exhibit broad heterogeneity in affiliative social behavior. Twin and family studies show that individual differences in core dimensions of social behavior are heritable, yet there are knowledge gaps in understanding the underlying genetic and neurobiological mechanisms. Animal genetic reference panels (GRPs) provide a tractable strategy for examining the behavioral and genetic architecture of complex traits. Here, using males from 50 mouse strains from the BXD GRP, 4 domains of affiliative social behavior--social approach, social recognition, direct social interaction (DSI) (partner sniffing) and vocal communication--were examined in 2 widely used behavioral tasks--the 3-chamber and DSI tasks. There was continuous and broad variation in social and nonsocial traits, with moderate to high heritability of social approach sniff preference (0.31), ultrasonic vocalization (USV) count (0.39), partner sniffing (0.51), locomotor activity (0.54-0.66) and anxiety-like behavior (0.36). Principal component analysis shows that variation in social and nonsocial traits are attributable to 5 independent factors. Genome-wide mapping identified significant quantitative trait loci for USV count on chromosome (Chr) 18 and locomotor activity on Chr X, with suggestive loci and candidate quantitative trait genes identified for all traits with one notable exception--partner sniffing in the DSI task. The results show heritable variation in sociability, which is independent of variation in activity and anxiety-like traits. In addition, a highly heritable and ethological domain of affiliative sociability--partner sniffing-- appears highly polygenic. These findings establish a basis for identifying functional natural variants, leading to a new understanding typical and atypical sociability. [ABSTRACT FROM AUTHOR]

• Soil fungal communities play an important role in the successful invasion of nonnative species. It is common for two or more invasive plant species to co-occur in invaded ecosystems. • This study aimed to determine the effects of co-invasion of two invasive species (Erigeron annuus and Solidago canadensis) with different cover classes on soil fungal communities using high-throughput sequencing. • Invasion of E. annuus and/or S. canadensis had positive effects on the sequence number, operational taxonomic unit (OTU) richness, Shannon diversity, abundance-based cover estimator (ACE index) and Chao1 index of soil fungal communities, but negative effects on the Simpson index. Thus, invasion of E. annuus and/or S. canadensis could increase diversity and richness of soil fungal communities but decrease dominance of some members of these communities, in part to facilitate plant further invasion, because high soil microbial diversity could increase soil functions and plant nutrient acquisition. Some soil fungal species grow well, whereas others tend to extinction after non-native plant invasion with increasing invasion degree and presumably time. The sequence number, OTU richness, Shannon diversity, ACE index and Chao1 index of soil fungal communities were higher under co-invasion of E. annuus and S. canadensis than under independent invasion of either individual species. • The co-invasion of the two invasive species had a positive synergistic effect on diversity and abundance of soil fungal communities, partly to build a soil microenvironment to enhance competitiveness of the invaders. The changed diversity and community under co-invasion could modify resource availability and niche differentiation within the soil fungal communities, mediated by differences in leaf litter quality and quantity, which can support different fungal/microbial species in the soil. [ABSTRACT FROM AUTHOR]

Aim The application of complete mesocolic excision (CME) in colon cancer is controversial. We performed a meta-analysis to compare the safety, quality and effect of CME with non-complete mesocolic excision (NCME) in patients with colon cancer. Method We searched PubMed, ScienceDirect, the Cochrane Library and Scopus to identify studies comparing CME with NCME in colon cancer. We focused on three study outcome areas: safety (operation time, blood loss, complications, mortality); quality (large bowel length, distance from the tumour to the high vascular tie, area of mesentery, total lymph nodes); and effect (long-term survival). Results A total of 8586 patients from 12 studies were included in the meta-analysis. CME was associated with greater intra-operative blood loss [weighted mean difference (WMD) 79.87, 95% CI: 65.88-93.86], more postoperative surgical complications (relative risk 1.23, 95% CI: 1.08-1.40), longer large bowel resection (WMD 47.06, 95% CI: 10.49-83.62), greater distance from the tumour to the high vascular tie (WMD 17.51, 95% CI: 15.16-19.87), larger area of mesentery (WMD 36.09, 95% CI: 18.06-54.13) and more lymph nodes (WMD 6.13, 95% CI: 1.97-10.28) than NCME. CME also had positive effects on 5-year survival [hazard ratio (HR) 0.33, 95% CI: 0.13-0.81], 3-year survival (HR 0.58, 95% CI: 0.39-0.86) and 3-year survival for Stage III disease (HR 0.69, 95% CI: 0.60-0.80) compared with NCME. Conclusion Limited evidence suggests that CME is a more effective strategy for improving specimen quality and survival but with a higher complication rate. [ABSTRACT FROM AUTHOR]

Both human and experimental evidence strongly supports the view of brain region- and cell-specific changes in tonic GABA inhibition in temporal lobe epilepsies ( TLE). This 'tonic' form of signalling is not time-locked to presynaptic action potentials, which depends upon detection of ambient GABA by extrasynaptic GABAA receptors ( GABAARs). Extrasynaptic GABAARs have distinct physiological and pharmacological features, including high GABA-binding affinity and low desensitization and a variety of the specific subunit combinations (α4δ-,α6δ-,α5γ-,ε-containing receptors). These features closely contribute to the function of tonic GABA current, which is preserved properly or increased in dentate gyrus in models of TLE, even in the face of a loss of synaptic inhibition and inhibitory interneurones. Markedly reduced tonic GABA inhibition may facilitate an episode of epilepsy, while persistent elevated tonic inhibition may contribute to the onset of spontaneous recurrent seizures. In dentate granule cells, tonic GABA inhibition is positively modulated by endogenous neurosteroids and other factors, which undergo changes related to hormonal status after TLE. Tonic inhibition regulates neuronal excitability through its effects on membrane potential by both offsetting the threshold and reducing the frequency of action potentials and input resistance. Therefore, extrasynaptic GABAARs are expected to be the most important pharmacological targets in TLE. It is likely that both elevate the ambient GABA concentration and potentiate the tonic currents, contributing to the antiepileptic effects. [ABSTRACT FROM AUTHOR]

The article discusses a feasibility study of a numerical technique to analyze the gas-diffusion layer (GDL) of a polymer electrolyte fuel cell (PEFC). The technique combines a digitally reconstructed three-dimensional (3-D) model of carbon paper GDL and 3-D two-phase lattice Boltzmann numerical model. A description of the X-ray nanotomography image generation and digital reconstruction process is presented. The study showed the effect of liquid intrusion pressures on intruded volume.

In the past two decades, the potential association between the risk of suicidal ideation and behavior and the clinical use of pharmaceutical products has been debated among industry, regulators, and academia. A better understanding of the possible effects-favorable, unfavorable, or neutral-of pharmaceuticals on the risk of suicidal ideation and behavior may be required, especially for trials typically designed for other primary objectives. Here, a cross-industry statistical team provides recommendations that address the assessment, statistical analysis, interpretation, and utility of suicide-related data in pharmaceutical clinical trials. These recommendations are to evaluate suicidal ideation, suicidal behavior, and the two combined as end points; utilize standard scales to collect data prospectively; and analyze the data using several statistical methods. A more accurate assessment of the potential association between the use of pharmaceutical products and risk of suicide-related events will contribute to estimating the benefit/risk ratio and result in safer medicines for patients. [ABSTRACT FROM AUTHOR]

An industrial-scale pulsed plasma-assisted chemical vapor deposition (PACVD) process for crystalline alumina growth was developed. To obtain a homogeneous coating thickness distribution over complex geometries and large dimensions, a suitable gas injection system was designed. A phase formation diagram for alumina coatings as a function of pulse length and cathode voltage has been compiled, allowing for the deposition of dense α/γ-Al2O3 coatings at a substrate temperature of 590 °C. Moulds coated with an α/γ-Al2O3 coating were utilized in steel thixocasting at temperatures of ∼1400 °C. The coatings were intact after thixocasting and showed significantly improved chemical wear resistance compared to plain steel moulds. [ABSTRACT FROM AUTHOR]

Forging is state-of-the-art for producing hand tools on an industrial scale. Due to high demands on the stiffness and the fracture toughness, high-strength forging steels are used to provide cavity-free components with high mechanical load capacity. Moreover, forging is a cost-effective mass production process but, in spite of all its advantages, it has its limitations, e.g. in the freedom of designs. However, because of the extreme thermal loading (particularly with regard to permanent moulds) and the frequently unavoidable casting defects, hand tools are not cast. By means of thixocasting steel, technical difficulties can be reduced and new options are provided which allow the manufacturing of components with much higher complexity than that using forging. Through near-net shape production, manufacturing steps and costs can be reduced. Furthermore, steels, which are difficult to forge but nonetheless have high potential for specific applications (such as high strength or corrosion resistant steels), can also be processed. In cooperation with industrial partners, X39CrMo17 stainless steel size 17 combination spanners were thixocast. Forming dies were designed and optimized by simulation, the hot forming X38CrMoV5 tool steel as well as the molybdenum alloy TZM were selected as the tool alloys. The dies were treated by a plasma nitriding process and subsequently coated with crystalline Al2O3 protective coatings by plasma-enhanced chemical vapor deposition (PECVD). During the experiments, combination spanners were successfully cast in the semi-solid state. Cast parts were heat-treated to enhance the components' toughness, which was subsequently measured by Charpy impact and tensile tests. [ABSTRACT FROM AUTHOR]

Abstract: Using Arabidopsis plants transformed with a redox-sensing green fluorescent protein targeted to the cytosol (c-roGFP1), we have demonstrated, in real time, measurements of reversible changes of redox status in the cytosol of plants subjected to a gradual water-stress, followed by re-watering. Plants sensed water stress, and changed the redox potential of their cytosol to a more oxidized value after a gradually-imposed water stress. Small variations in the cytosol redox potential and ascorbate (AA) values suggest that this parameter was tightly regulated. The re-watering was paralleled by a return of water stress, redox potential and ascorbate to initial values, showing the reversibility of water stress and its consequences. [Copyright &y& Elsevier]

OBJECTIVE: The development of biomarkers to predict response to therapy in polyarticular juvenile idiopathic arthritis (JIA) is an important issue in pediatric rheumatology. A critical step in this process is determining whether there is biologic meaning to clinically derived terms such as 'active disease' and 'remission.' The aim of this study was to use a systems biology approach to address this question. METHODS: We performed gene transcriptional profiling on children who fulfilled the criteria for specific disease states as defined by the consensus criteria developed by Wallace and colleagues. The study group comprised children with active disease (n = 14), children with clinical remission on medication (CRM; n = 9), children with clinical remission off medication (CR; n = 6), and healthy control children (n = 13). Transcriptional profiles in peripheral blood mononuclear cells (PBMCs) were obtained using Affymetrix U133 Plus 2.0 arrays. RESULTS: Hierarchical cluster analysis and predictive modeling demonstrated that the clinically derived criteria represent biologically distinct states. Minimal differences were seen between children with active disease and those with disease in CRM. Thus, underlying immune/inflammatory abnormalities persist despite a response to therapy. The PBMC transcriptional profiles of children whose disease was in remission did not return to normal but revealed networks of proinflammatory and antiinflammatory genes, suggesting that remission is a state of homeostasis, not a return to a normal state. CONCLUSION: Gene transcriptional profiling of PBMCs revealed that clinically derived criteria for JIA disease states reflect underlying biology. We also demonstrated that neither CRM nor CR status results in resolution of the underlying inflammatory process, but that these conditions are more likely to be states of balanced homeostasis between proinflammatory and antiinflammatory mechanisms. [ABSTRACT FROM AUTHOR]