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The electrical conductivity of the Earth’s core is an important physical parameter that controls the core dynamics and the thermal evolution of the Earth. In this study, the effect of core electrical conductivity on core surface flow models is investigated. Core surface flow is derived from a geomagnetic field model on the presumption that a viscous boundary layer forms at the core–mantle boundary. Inside the boundary layer, where the viscous force plays an important role in force balance, temporal variations of the magnetic field are caused by magnetic diffusion as well as motional induction. Below the boundary layer, where core flow is assumed to be in tangentially geostrophic balance or tangentially magnetostrophic balance, contributions of magnetic diffusion to temporal variation of the magnetic field are neglected. Under the constraint that the core flow is tangentially geostrophic beneath the boundary layer, the core electrical conductivity in the range from 105Sm-1 to 107Sm-1 has less significant effect on the core flow. Under the constraint that the core flow is tangentially magnetostrophic beneath the boundary layer, the influence of electrical conductivity on the core flow models can be clearly recognized; the magnitude of the mean toroidal flow does not increase or decrease, but that of the mean poloidal flow increases with an increase in core electrical conductivity. This difference arises from the Lorentz force, which can be stronger than the Coriolis force, for higher electrical conductivity, since the Lorentz force is proportional to the electrical conductivity. In other words, the Elsasser number, which represents the ratio of the Lorentz force to the Coriolis force, has an influence on the difference. The result implies that the ratio of toroidal to poloidal flow magnitudes has been changing in accordance with secular changes of rotation rate of the Earth and of core electrical conductivity due to a decrease in core temperature throughout the thermal evolution of the Earth.

This study proposes a neural network approach for predicting the geomagnetic secular variation (SV) to improve the accuracy and efficiency of short-term geomagnetic forecasts. The International Geomagnetic Reference Field (IGRF), updated every five years, provides a standardized representation of Earth’s magnetic field, including a 5-year linear prediction of SV. Recent forecasting methods, which are reliant on computationally intensive geodynamo simulations, often struggle to capture sudden changes due to nonlinearity, such as the geomagnetic jerk. We have developed a novel recurrent neural network (RNN) framework trained using the extended Kalman filter (EKF), termed the EKF-RNN, to address these challenges. Unlike conventional backpropagation methods, the EKF dynamically updates the RNN weights by incorporating error covariance from training data, effectively mitigating overfitting while preserving computational efficiency. The EKF-RNN model is validated through hindcast experiments for epochs 2004.87 to 2014.62, utilizing geomagnetic field snapshots derived from satellite and ground magnetic observations. The results exhibit forecast errors below 85 nT for 5-year predictions, outperforming known data assimilation methods such as 4dEnVar. Additionally, the EKF-RNN method provides forecast error covariance matrices, offering enhanced interpretability and robustness compared to earlier neural network models. This research underscores the potential of EKF-RNN for reliable geomagnetic SV predictions, contributing to the accuracy of the 14th-generation IGRF and advancing data-driven approaches in geomagnetic field modeling. Graphical Abstract

Abstract Rationale To detect pulmonary arterial hypertension (PAH) at any early stage is a promising approach to optimize the outcome. Objectives To investigate the impact of school ECG-based screening on detecting idiopathic or heritable (I/H)-PAH in the general pediatric population. Methods This was a nationwide survey of patients with I/H-PAH newly diagnosed at 3 months to 18 years of age in Japan during 2005–2012. Measurements and Main Results Eighty-seven eligible patients (age range, 1–16 yr) were recruited. Among 68 (78%) patients diagnosed at greater than or equal to 6 years of age (the age of the first ECG-based screening), 28 (41%) were detected by the ECG-based screening (screening group) and 40 (59%) were recognized by their symptoms (n = 37) or coincidental occasions (n = 3; nonscreening group). In the screening group, the proportion of patients in World Health Organization functional class I/II at diagnosis was higher (96% vs. 60%; P < 0.001), plasma brain natriuretic peptide level was lower (149 ± 290 vs. 398 ± 559 pg/ml; P = 0.045), and 6-minute-walk distance was longer (420 ± 109 vs. 327 ± 104 m; P < 0.001) than the nonscreening group, despite similar values in mean pulmonary artery pressure (58 ± 17 vs. 61 ± 17 mm Hg; P = 0.42) and pulmonary vascular resistance index (18 ± 8 vs. 21 ± 11 Wood units ⋅ m2; P = 0.24) between groups. The proportion of patients on intravenous epoprostenol at the final visit was lower in the screening group than the nonscreening group (14% vs. 50; P = 0.004). Conclusions These findings suggest that the ECG-based screening detects a unique subpopulation of pediatric patients with I/H-PAH that is associated with already established pulmonary hypertension but without obvious right heart failure and warrants investigating the prognostic significance of this system.

Noonan syndrome is characterized by short stature, facial dysmorphia and a wide spectrum of congenital heart defects 1 , 2 . Mutations of PTPN11 , KRAS and SOS1 in the RAS-MAPK pathway cause ∼60% of cases of Noonan syndrome 3 , 4 , 5 , 6 , 7 , 8 , 9 . However, the gene(s) responsible for the remainder are unknown. We have identified five different mutations in RAF1 in ten individuals with Noonan syndrome; those with any of four mutations causing changes in the CR2 domain of RAF1 had hypertrophic cardiomyopathy (HCM), whereas affected individuals with mutations leading to changes in the CR3 domain did not. Cells transfected with constructs containing Noonan syndrome–associated RAF1 mutations showed increased in vitro kinase and ERK activation, and zebrafish embryos with morpholino knockdown of raf1 demonstrated the need for raf1 for the development of normal myocardial structure and function. Thus, our findings implicate RAF1 gain-of-function mutations as a causative agent of a human developmental disorder, representing a new genetic mechanism for the activation of the MAPK pathway.

Wave–particle interactions are fundamental processes in space plasma, and some plasma waves, including electrostatic solitary waves (ESWs), are recognised as broadband noises (BBNs) in the electric field spectral data. Spacecraft observations in recent decades have detected BBNs around the Moon, but the generation mechanism of the BBNs is not fully understood. Here, we study a wake boundary traversal with BBNs observed by Kaguya, which includes an ESW event previously reported by Hashimoto et al. Geophys Res Lett 37:L19204 https://doi.org/10.1029/2010GL044529 (2010). Focusing on the relation between BBNs and electron pitch-angle distribution functions, we show that upward electron beams from the nightside lunar surface are effective for the generation of BBNs, in contrast to the original interpretation by Hashimoto et al. Geophys Res Lett 37:L19204 https://doi.org/10.1029/2010GL044529 (2010) that high-energy electrons accelerated by strong ambipolar electric fields excite ESWs in the region far from the Moon. When the BBNs were observed by the Kaguya spacecraft in the wake boundary, the spacecraft’s location was magnetically connected to the nightside lunar surface, and bi-streaming electron distributions of downward-going solar wind strahl component and upward-going field-aligned beams (at ∼124 eV) were detected. The interplanetary magnetic field was dominated by a positive BZ (i.e. the northward component), and strahl electrons travelled in the antiparallel direction to the interplanetary magnetic field (i.e. southward), which enabled the strahl electrons to precipitate onto the nightside lunar surface directly. The incident solar wind electrons cause negative charging of the nightside lunar surface, which generates downward electric fields that accelerate electrons from the nightside surface toward higher altitudes along the magnetic field. The bidirectional electron distribution is not a sufficient condition for the BBN generation, and the distribution of upward electron beams seems to be correlated with the BBNs. Ambipolar electric fields in the wake boundary should also contribute to the electron acceleration toward higher altitudes and further intrusion of the solar wind ions into the deeper wake. We suggest that solar wind ion intrusion into the wake boundary is also an important factor that controls the BBN generation by facilitating the influx of solar wind electrons there.

The Moon has no global intrinsic magnetic field and only has a very thin atmosphere. Ion measurements made from lunar orbit provide us with information regarding interactions between the solar wind and planetary surface, the surface composition through secondary ion mass spectrometry and the source and loss mechanisms of planetary tenuous atmosphere. An ion energy mass spectrometer MAP‐PACE IMA onboard a lunar orbiter SELENE (KAGUYA) has detected low‐energy ions at 100‐km altitude. The MAP‐PACE measurements have elucidated that the ions originate from the lunar surface and exosphere and that the ions are at least composed of He+, C+, O+, Na+ and K+. Following the discovery of the lunar Na and K exospheres by the ground‐based observation, MAP‐PACE IMA have found the He, C and O exospheres around the Moon.

An active core dynamo may have operated on the early Moon. Extraction of palaeomagnetic pole positions on the Moon from magnetic anomalies measured by the Lunar Prospector and Kaguya orbiters suggests that the ancient lunar dynamo experienced reversals and an ancient reorientation of the Moon rotated the geographic locations of the poles. Palaeomagnetic measurements suggest that an active core dynamo operated on the Moon from 4.2 to 3.56 billion years ago 1 , 2 , 3 . Since the Apollo era, many magnetic anomalies have been observed on the Moon. The magnetization of the lunar crust in some of these regions could preserve the signature of an early dipolar magnetic field generated by a core dynamo. Thus, the magnetic anomalies may yield information about the position of the palaeomagnetic pole during the time that the dynamo operated. Here we present a comprehensive survey of magnetic anomalies on the lunar surface using magnetometer data 4 , 5 obtained by the Lunar Prospector and Kaguya lunar orbiters. We extract magnetization vectors from 24 magnetic anomalies using an iterative inversion method and derive the palaeomagnetic poles. We find that the north poles, as well as the antipodal south poles, cluster in two distinct locations: one near the present rotation axis and the other at mid-latitude. The clustering is consistent with a dipole-dominated magnetic field generated in the lunar core by a dynamo that was reversing, much like that of Earth. Furthermore, the two pole clusters imply that the Moon experienced a polar wander event during its ancient history due to the reorientation of the Moon with respect to its spin axis by 45°–60°.

In contrast to many ground‐based optical observations of the thin lunar alkali exosphere, in situ observations of the exospheric ions by satellite‐borne plasma instruments have been quite rare. MAP‐PACE‐IMA onboard Japanese lunar orbiter SELENE (KAGUYA) succeeded in detecting Moon originating ions at 100 km altitude. Here we make the first report of the ion detection during intervals when the Moon was embedded in the Earth's magnetotail lobe. In the absence of plasma effects on the source process, ion species of H+, He++, He+, C+, O+, Na+, K+ and Ar+ are definitively identified. The ion fluxes were higher when the solar zenith angle was smaller, which is consistent with the idea that the solar photon driven processes dominates in supplying exospheric components.

Large amplitude, monochromatic ultra low frequency (ULF) waves were detected by MAP/LMAG magnetometer onboard Kaguya during the period from 1 January 2008 to 30 November 2008 on its orbit 100 km above the lunar surface. The dominant frequency was 8.3 × 10−3 – 1.0 × 10−2 Hz, corresponding to the periods of 120 s – 100 s. The amplitude was as large as 3 nT. They were observed in 10% of the time when the moon was in the solar wind far upstream of the Earth's bow shock. They were detected only by Kaguya on the orbit around the moon, but not by ACE in the upstream solar wind. The occurrence rate was high above the terminator and on the dayside surface. The direction of the propagation was not exactly parallel to the interplanetary magnetic field, but showed a preference to the direction of the magnetic field and the direction perpendicular to the surface of the moon below the spacecraft. The sense of rotation of the magnetic field was left‐handed with respect to the magnetic field in 53% of the events, while 47% showed right‐handed polarization. The possible generation mechanism is the cyclotron resonance of the magnetohydrodynamic waves with the solar wind protons reflected by the moon. The energy of the reflected protons can account for the energy of the ULF waves. The propagation direction which are not parallel to the incident solar wind flow can explain the observed frequency and the nearly equal percentages of the left‐handed and right‐handed polarizations. Key Points Monochromatic ULF waves were detected by Kaguya on its orbit around the Moon The ULF waves were generated by the solar wind protons reflected by the Moon The generation mechanism is the cyclotron resonance with solar wind MHD waves

Crustal fluids exist near fault zones, but their relation to the processes that generate earthquakes, including slow-slip events, is unclear. Fault-zone fluids are characterized by low electrical resistivity. Here we investigate the time-dependent crustal resistivity in the rupture area of the 1999 M w 7.6 Izmit earthquake using electromagnetic data acquired at four sites before and after the earthquake. Most estimates of apparent resistivity in the frequency range of 0.05 to 2.0 Hz show abrupt co-seismic decreases on the order of tens of per cent. Data acquired at two sites 1 month after the Izmit earthquake indicate that the resistivity had already returned to pre-seismic levels. We interpret such changes as the pressure-induced transition between isolated and interconnected fluids. Some data show pre-seismic changes and this suggests that the transition is associated with foreshocks and slow-slip events before large earthquakes. Low-resistivity crustal fluids occur near fault zones, but their relation to earthquake generation is unclear. Here, electromagnetic data from the Izmit earthquake reflects the pressure-induced transition between isolated and interconnected fluids that is linked to foreshocks before large earthquakes.