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As the only remaining ice sheet in the Northern Hemisphere, the Greenland ice sheet (GrIS) plays a crucial role in influencing atmospheric circulations, particularly with its rapid melting under global warming. In this paper, the influences of GrIS topography and surface thermal conditions are investigated by a series of aquaplanet experiments. The results show that the GrIS topography induces stationary waves and favors more blocking events through the generation of negative potential vorticity (PV) anomalies, while it tends to suppress local storm activities through the induced stationary waves. The surface cooling center of the GrIS is found to strengthen the jet streams by enhancing the meridional temperature gradient and thermal wind, while it causes the PV and static stability to increase during near-Greenland blocking days, thereby disfavoring blocking onset. Altogether, the topography and surface thermal effects of GrIS appear to compete with each other so that the net effect would determine the final response. Nevertheless, nonlinearity is found in both GrIS-topography alone and GrIS-surface temperature alone experiments, where nonlinear responses of atmospheric circulation are detected when the GrIS topography height or surface temperature exceeds their critical values, respectively. Hence, through this study, the response of the blocking in the vicinity of Greenland to the combined effects of topography and surface thermal conditions may shed light on comprehending the underlying mechanism of blocking alteration in a changing climate. Significance Statement: Although there have been numerous observation-based studies showing that the blocking around Greenland has increased over the past few decades, which is a predominant driver in accelerating the Greenland ice sheet (GrIS) melting, the reasons for this change are still unclear. In addition, the impact of GrIS on blocking still needs investigation. Through idealized aquaplanet simulations, this study examines the effect of GrIS's topography and surface thermal conditions upon blocking onset. It suggests the nonlinearity of the blocking response in the vicinity of Greenland to the combined effects in the variation of the height and surface temperature of GrIS. This study will enhance our understanding of possible changes in blocking due to global warming. [ABSTRACT FROM AUTHOR]

Large-scale genomic projects and ancient DNA innovations have ushered in a new paradigm for exploring human evolutionary history. However, the genetic legacy of spatiotemporally diverse ancient Eurasians within Chinese paternal lineages remains unresolved. Here, we report an integrated Y-chromosome genomic database encompassing 15,563 individuals from both modern and ancient Eurasians, including 919 newly reported individuals, to investigate the Chinese paternal genomic diversity. The high-resolution, time-stamped phylogeny reveals multiple diversification events and extensive expansions in the early and middle Neolithic. We identify four major ancient population movements, each associated with technological innovations that have shaped the Chinese paternal landscape. First, the expansion of early East Asians and millet farmers from the Yellow River Basin predominantly carrying O2/D subclades significantly influenced the formation of the Sino-Tibetan people and facilitated the permanent settlement of the Tibetan Plateau. Second, the dispersal of rice farmers from the Yangtze River Valley carrying O1 and certain O2 sublineages reshapes the genetic makeup of southern Han Chinese, as well as the Tai-Kadai, Austronesian, Hmong-Mien, and Austroasiatic people. Third, the Neolithic Siberian Q/C paternal lineages originated and proliferated among hunter-gatherers on the Mongolian Plateau and the Amur River Basin, leaving a significant imprint on the gene pools of northern China. Fourth, the J/G/R paternal lineages derived from western Eurasia, which were initially spread by Yamnaya-related steppe pastoralists, maintain their presence primarily in northwestern China. Overall, our research provides comprehensive genetic evidence elucidating the significant impact of interactions with culturally distinct ancient Eurasians on the patterns of paternal diversity in modern Chinese populations. [ABSTRACT FROM AUTHOR]

Using the high‐time‐resolution data from the Magnetospheric Multiscale mission, precursor waves upstream of foreshock transient (FT) shocks are statistically investigated using the four‐spacecraft timing method. The wave frequencies and wave vectors determined in the plasma rest frame (PRF) are shown to follow the cold plasma dispersion relation for whistler waves. Combining with the feature of the right‐hand polarization in the PRF, the precursors are identified as whistler‐mode waves around the lower hybrid frequency. The occurrence of whistler precursors is independent of the Alfvén Mach number and the FT shock normal angle. More importantly, all the whistler precursors have group velocities pointing upstream in the shock frame, suggesting the dispersive radiation to be a possible generation mechanism. The study improves the understanding of not only the whistler precursors but also the overall FT shock dynamics. Plain Language Summary: The characteristics of the precursor waves upstream of foreshock transient (FT) shocks are determined in the plasma rest frame using the multi‐point measurements from the Magnetospheric Multiscale mission with appropriate separation scales. The statistical results demonstrate for the first time that the precursors upstream of FT shocks are lower hybrid frequency whistler‐mode waves. The presence or absence of large amplitude whistler precursors does not depend on the FT shock normal angle and the Alfvén Mach number. These results have important implications on the nature of the whistler precursors and the dynamics of the FT shocks. Key Points: Precursor waves upstream of foreshock transient shocks are found to follow the whistler wave dispersion relation in the plasma rest frameThe occurrence of whistler precursors is independent of the Alfvén Mach numbers and normal angles of the foreshock transient shocksThe observed wave characteristics are consistent with that the precursors are generated through the dispersive radiation mechanism [ABSTRACT FROM AUTHOR]

The scattering of charged particles by oxygen ion cyclotron harmonic (OCH) waves in the inner magnetosphere is investigated by evaluating the relevant quasi‐linear diffusion coefficients. Recent studies demonstrated that OCH waves are oxygen ion Bernstein modes and their complex kinetic dispersion relation has made it challenging to assess their role in scattering charged particles. The present study calculates the quasi‐linear diffusion coefficients for the scattering of electrons and ions by OCH waves using their kinetic dispersion relation. The results show that OCH waves can effectively scatter electrons between ∼100 eV and 100s keV via Landau resonance. They are also capable of heating cold helium and oxygen ions through cyclotron resonances. Specially, it is found that the 4th harmonic of OCH waves can lead to effective heating of helium ions, while oxygen ions would interact more efficiently with lower harmonics of OCH waves. Plain Language Summary: Oxygen ion cyclotron harmonic (OCH) waves observed in the inner magnetosphere often have multiple spectral peaks at harmonics of the local oxygen ion cyclotron frequency. They have been shown to be excited by hot oxygen ion loss‐cone or ring/ring‐like distributions and follow a complicated kinetic dispersion relation for oxygen ion Bernstein waves. Since OCH waves cannot be described by the relatively simple cold plasma dispersion relation, it has been difficult to calculate their diffusion coefficients in scattering charged particles in quasi‐linear theory. The present study numerically solves the kinetic dispersion relation for OCH waves and then uses the results to calculate the corresponding quasi‐linear diffusion coefficients for electrons and ions. The diffusion coefficients obtained show that OCH waves can effectively interact with ∼100 eV to 100s keV electrons and are capable of heating cold helium and oxygen ions. Thus, OCH waves have their own unique contribution to the particle dynamics in the inner magnetosphere. Key Points: Quasi‐linear diffusion coefficients are evaluated for particle scattering by oxygen ion cyclotron harmonic (OCH) waves for the first timeOCH waves can scatter electrons in a wide energy range (∼100 eV–100s keV) via Landau resonanceOCH waves are capable of heating cold helium and oxygen ions through cyclotron resonance [ABSTRACT FROM AUTHOR]

The effects of plasma density on the plasmaspheric hiss amplitude and its spatial and temporal scale sizes are investigated using data from Van Allen Probes A and B. The plasmaspheric hiss amplitude and scale sizes are found to be more affected by the small‐scale density variations than the overall density profile of the plasmasphere. In detail, our results suggest that both the hiss wave amplitude and its scale sizes are (a) related to the total electron density when the density is less than ∼1,000 cm−3; (b) independent of the total electron density when the density is greater than ∼1,000 cm−3; and (c) better correlated with the detrended density (removing the background plasmasphere density profile from the total electron density) regardless of the density value. Key Points: Effects of plasma density on the spatial and temporal scale sizes of plasmaspheric hiss amplitude is statistically investigatedThe plasmaspheric hiss amplitude is better correlated with the detrended electron density than the total electron densityThe spatial and temporal scale sizes of plasmaspheric hiss are mainly related to that of the relatively small‐scale density variations [ABSTRACT FROM AUTHOR]

Large total electron content (TEC) variations along the line from Mars to Earth have been demonstrated by analyzing the ground received Tianwen‐1 differential one‐way range (DOR) signals when corona mass ejections (CMEs) and co‐rotating interaction regions (CIRs) pass through the signal path. Here, the TEC variations along the line from Mars to Earth are calculated from the Wang‐Sheeley‐Arge (WSA)‐Enlil space weather forecast model. The results are compared with the Tianwen‐1 line of sight (LOS) observations as well as the STEREO‐A in situ solar wind density measurements. It is found that the TEC variations calculated from the WSA‐Enlil model are usually much smaller in amplitude, especially in the cases of CIRs passing through the signal path. In addition, the timings of CMEs and CIRs passing through the DOR signal path in the WSA‐Enlil model can be half a day earlier or later than the observed ones. In comparison with in situ solar wind measurements, the ground received Tianwen‐1 DOR signals carry solar wind density information over a large spatial region along the signal path. Such remote sensing measurement can be valuable for constraining and improving global solar wind forecast models. Plain Language Summary: Space weather forecast is important for ground‐based and space‐borne technology, including power grids, satellite navigation, and satellite radio communication. Wang‐Sheeley‐Arge (WSA)‐Enlil is one of the current advanced models to predict the space weather. We calculate the amount of charged particles along the line from Mars to Earth from the model, and compare it with the observed one by remote sensing method. Significant differences exist between the two results. It is, therefore, suggested that space weather forecast models should incorporate those remote sensing measurements, which may make the space weather forecast more accurate. Key Points: TEC variations along the line from Mars to Earth in the cases of CMEs and CIRs passing through are calculated from the WSA‐Enlil modelIn comparison with the TEC variations obtained from the Tianwen‐1 DOR signals, the WSA‐Enlil model results are far from realisticThe Tianwen‐1 DOR signals carry solar wind density information along the signal path and can help to constrain solar wind forecast models [ABSTRACT FROM AUTHOR]

Bicoherence analysis is statistically performed for the oxygen ion cyclotron harmonic (OCH) waves observed by Van Allen Probes. While OCH waves and so‐called electromagnetic ion cyclotron harmonics have indistinguishable spectral characteristics in observation, they are believed to be excited by different mechanisms with the latter being suggested to arise from nonlinear wave‐wave coupling. Our result reveals that most of the OCH wave events have small bicoherence indices, so they are unlikely excited by wave‐wave coupling. The result is not much affected by the parameter choice in the bicoherence analysis, although increasing the subinterval length and/or reducing the subinterval overlap increases the chance of getting large bicoherence index values. Furthermore, the examination of two special events with large bicoherence indices shows that the observed phase relationship among different wave components does not align with the expectation from wave‐wave coupling. The events cannot be convincingly confirmed to be generated through wave‐wave coupling. Plain Language Summary: This paper presents a statistical bicoherence analysis study of the oxygen ion cyclotron harmonic (OCH) waves observed by Van Allen Probes. OCH waves have apparent features similar to electromagnetic ion cyclotron (EMIC) harmonics in observation. Previous studies have suggested that OCH waves are excited through the oxygen ion Bernstein instability but EMIC harmonics are generated by nonlinear wave‐wave coupling. Bicoherence analysis is commonly employed for assessing wave‐wave coupling. The results of our bicoherence analysis indicate that most of the OCH events have bicoherence indices less than 0.5, so they are unlikely generated through wave‐wave coupling. The study also demonstrates that the parameter choice in bicoherence analysis affects the calculated index values, but the index values remain mostly less than 0.5 for the various reasonable parameter choices tested. In addition, a detailed analysis of the phase relationship among various electric and magnetic wave components in two specific OCH events reveals that, despite their large bicoherence indices, the observed phase relationship does not align with what would be expected if the waves are generated from wave‐wave coupling. This reminds us that having a large bicoherence index is a necessary but not sufficient condition to prove that waves are generated by wave‐wave coupling. Key Points: Most of the oxygen ion cyclotron harmonic (OCH) waves observed by Van Allen Probes have small bicoherence indicesIncreasing the subinterval length and/or reducing the subinterval overlap increases the chance of getting large bicoherence index valuesExamination of two special OCH wave events with large bicoherence indices does not support them being generated from wave‐wave coupling [ABSTRACT FROM AUTHOR]

In this study, we differentiate wet processes from dry processes in shaping the extratropical thermal stratification during the Last Glacial Maximum. Our findings indicate that even during the dry glacial period the influence of wet processes on thermal stratification cannot be overlooked. The applicability of dry and wet baroclinic adjustment theory strongly depends on the seasonality rather than the glaciation as the warm season is characterized by a weaker meridional temperature gradient and increased precipitation than the cold season. Despite that the baroclinic adjustment theory based on effective static stability can be proficiently applied to all seasons, the classical dry baroclinic adjustment theory may be better suited for use during relatively cold seasons. These findings have important implications for understanding processes governing the extratropical thermal stratification, particularly in the context of cold climate. Plain Language Summary: In this study, we examined how different processes affect the formation of the extratropical thermal stratification during the Last Glacial Maximum. We found that both dry and wet processes play a crucial role, with the wet processes being particularly important during warm seasons. Our results suggest that the importance of wet process is largely dependent on the seasonality instead of glaciation. These findings help to improve our understanding of the extratropical thermal stratification and its governing processes, particularly in the context of cold climates. Key Points: The study differentiates wet process from dry process in shaping extratropical thermal stratification during the Last Glacial MaximumEven during the dry glacial period, wet processes still poses a significant influence on thermal stratificationSeasonality governs dry and wet baroclinic adjustment theory applicability, with the dry theory being more suited for cold seasons [ABSTRACT FROM AUTHOR]

Wireless body area networks (WBANs) can be used to realize the real-time monitoring and transmission of health data concerning the human body based on wireless communication technology. With the transmission of these sensitive health data, security and privacy protection issues have become increasingly prominent. Fine-grained authentication allows physicians to run authentication checks of another specific entity according to their identifying attributes. Hence, it plays a key role in preserving the security and privacy of WBANs. In recent years, substantial research has been carried out on fine-grained authentication. However, these studies have put considerable effort into WBAN performances, resulting in weakened security. This paper proposes a fine-grained user authentication and key agreement protocol based on physical unclonable functions (PUFs) while maintaining robust security and performance. This will allow physicians to perform mutual authentication and obtain key agreements with authorized body area sensor nodes according to their identity parameters, such as occupation type and title. We then provide comprehensive security and heuristic analyses to demonstrate the security of the proposed protocol. Finally, the performance comparison shows that the proposed protocol is more robust in security, cost-effective communication, and computational overheads compared to three leading alternatives. [ABSTRACT FROM AUTHOR]

In healthcare, wireless body area networks (WBANs) can be used to constantly collect patient body data and assist in real-time medical services for patients from physicians. In such security- and privacy-critical systems, the user authentication mechanism can be fundamentally expected to prevent illegal access and privacy leakage occurrences issued by hacker intrusion. Currently, a significant quantity of new WBAN-oriented authentication protocols have been designed to verify user identity and ensure that body data are accessed only with a session key. However, those newly published protocols still unavoidably affect session key security and user privacy due to the lack of forward secrecy, mutual authentication, user anonymity, etc. To solve this problem, this paper designs a robust user authentication protocol. By checking the integrity of the message sent by the other party, the communication entity verifies the other party's identity validity. Compared with existing protocols, the presented protocol enhances security and privacy while maintaining the efficiency of computation. [ABSTRACT FROM AUTHOR]

The processes governing tropospheric stratification alterations during the Last Glacial Maximum (LGM) are investigated using the Paleoclimate Modeling Intercomparison Project Phase 3/4 (PMIP3/PMIP4) simulations. The results demonstrate a decrease in static stability in the tropics during both December‐January‐February (DJF) and June‐July‐August (JJA), while an increase is observed in the extratropics during DJF. Further analysis reveals that the rise in static stability over high‐latitude ocean is driven by shifts in surface frozen lines, whereas the increased static stability over ice sheet margins is due to the cooling effect of ice sheet slopes. The study finds that the dry static stability change in ice sheet‐covered areas remains significant and robust in both PMIP3 and PMIP4. However, a weaker stabilization signal is detected in the North Atlantic in PMIP4. These findings provide valuable insights into the processes shaping tropospheric stratification during the LGM and underscore the importance of accounting for ice sheet effects in paleoclimate simulations. Plain Language Summary: The Last Glacial Maximum (LGM) is a cold period in the Earth history. Here, we use numerical model data from the Paleoclimate Modeling Intercomparison Project Phase 3/4 (PMIP3/PMIP4) to investigate the atmospheric stability change during the period. The results indicate that the low latitude atmosphere was more unstable during both December‐January‐February (DJF) and June‐July‐August (JJA), whereas the midlatitude and high‐latitude atmospheres were only more stable during DJF. The latter stabilization is mostly related to the sea ice activities and cold surface of ice sheet slope. Key Points: During the Last Glacial Maximum (LGM), in the Northern Hemisphere (NH) static stability decreases in the tropics during both summer and winter due to weakening convection activitiesDuring the LGM, in NH winter, increase in static stability over high‐latitude ocean results from the shift in frozen linesDuring the LGM, in NH winter, increase in static stability over ice sheet margins mostly results from the ice sheet slope cooling effect [ABSTRACT FROM AUTHOR]

Nanozymes are artificial enzymes that mimic natural enzyme-like activities and exhibit tremendous potential for tumor chemodynamic therapy. However, the development of novel nanozymes with superior catalytic activities for nanotheranostics remains a formidable challenge. Herein, we report a facile synthesis of monodisperse palladium nanosheets (Pd nanosheets) and their assembly on graphene oxide (GO) that enhances the catalytic activities of Pd nanoparticles. Simultaneously, the obtained nanocomposites (rGO-Pd) could be applied as a smart near-infrared (NIR) light-responsive nanotheranostic for near infrared imaging-guided chemodynamic/photothermal combined therapy. Notably, rGO-Pd exhibited high peroxidase mimicking activities, which could catalyze the conversion of intratumoral H2O2 to ˙OH. Impressively, the reactive oxygen species (ROS) generation of rGO-Pd was further remarkably enhanced by the endogenous acidity of the tumor microenvironment and the exogenous NIR light-responsive photothermal effect. These collective properties of the rGO-Pd nanozyme enabled it to be a ROS generation accelerator for photothermally enhanced tumor chemodynamic therapy. Thus, the as-developed rGO-Pd may represent a promising new type of high-performance nanozyme for multifunctional nanotheranostics toward cancer. [ABSTRACT FROM AUTHOR]

Linear instability analysis as well as a corresponding two‐dimensional hybrid simulation are performed to examine the excitation of the proton cyclotron waves observed upstream of Mars. The waves are believed to be excited by the pickup ions produced from the ionization of the Martian hydrogen exosphere. And previous statistical analysis of wave observations suggested that the waves are mostly related to pickup ion beam velocity distributions. While earlier linear instability analysis of pickup ion beam distributions has mainly been focused on the parallel unstable modes, our analysis reveals that the maximum growth rate occurs at very oblique propagation. The corresponding hybrid simulation confirms the linear analysis results and further demonstrates that the pickup ions are scattered toward an isotropic shell velocity distribution by the waves excited. Interestingly, the waves at oblique propagation gradually damp out and the system is eventually dominated by waves of quasi‐parallel propagation. Plain Language Summary: Waves near the local proton cyclotron frequency have commonly been observed upstream of Mars. Without the shielding of a global intrinsic magnetic field, the Martian exosphere interacts directly with the solar wind. Pickup ions are generated when neutrals in the exosphere are ionized and "picked up" by the solar wind. Observations suggested that the proton cyclotron waves upstream of Mars are excited by the newborn pickup ions, especially when they have a large drift along the background magnetic field with respect to the solar wind ions (i.e., a beam velocity distribution). The present study carries out linear instability analysis for pickup ions of a beam distribution. The results reveal the most unstable wave at large propagation angle, in contrast to previous analysis mainly focused on parallel unstable modes. Our subsequent hybrid simulation confirms the linear theory prediction and demonstrates the scattering of the pickup ions by the enhanced waves. More importantly, although the oblique waves grow first, they also fade away faster so that the simulation is dominated by waves at quasi‐parallel propagation in the late stage. Key Points: Pickup ion beam distribution can generate the left‐hand polarized proton cyclotron waves observed upstream of Mars after Doppler shiftThe maximum growth rate occurs at oblique propagation instead of parallel propagationEnhanced waves pitch angle scatter pickup ions toward an isotropic shell velocity distribution [ABSTRACT FROM AUTHOR]

Flourishing online retailing has spawned the agency selling channel, which motivates suppliers to choose among traditional reselling (R), agency selling (A), and hybrid channel strategies (H). In this paper, considering a supplier and a retail platform facing strategic consumers, we develop a Stackelberg game to examine the equilibrium pricing under three channel strategies and further analyze the impact of consumer strategic behavior on the supplier's channel selection. Results indicate that consumer strategic behaviors induce the intertemporal competition, by reducing the price difference between the two periods. Meanwhile, channel competition can mitigate the effect of strategic behaviors. Furthermore, supply chain members also employ different pricing policies in accordance with channel strategies to respond to more strategic consumers. Specifically, prices would be raised to acquire high-valued consumers in Strategy H, while "small profits but quick turnover" would be taken in the pure channel strategies. Moreover, the supplier optimal channel strategy is a threshold strategies of commission rate, below which Strategy H is preferred, and Strategy R is preferred otherwise, noticing that Strategy A is never be selected. Interestingly, we find that the supplier, retail platform, and consumers could be better off at the same time only when the hybrid channel strategy is selected. [ABSTRACT FROM AUTHOR]

Background: The ulcerative colitis (UC) Mayo endoscopy score is a useful tool for evaluating the severity of UC in patients in clinical practice. Objectives: We aimed to develop and validate a deep learning-based approach to automatically predict the Mayo endoscopic score using UC endoscopic images. Design: A multicenter, diagnostic retrospective study. Methods: We collected 15120 colonoscopy images of 768 UC patients from two hospitals in China and developed a deep model based on a vision transformer named the UC-former. The performance of the UC-former was compared with that of six endoscopists on the internal test set. Furthermore, multicenter validation from three hospitals was also carried out to evaluate UC-former's generalization performance. Results: On the internal test set, the areas under the curve of Mayo 0, Mayo 1, Mayo 2, and Mayo 3 achieved by the UC-former were 0.998, 0.984, 0.973, and 0.990, respectively. The accuracy (ACC) achieved by the UC-former was 90.8%, which is higher than that achieved by the best senior endoscopist. For three multicenter external validations, the ACC was 82.4%, 85.0%, and 83.6%, respectively. Conclusions: The developed UC-former could achieve high ACC, fidelity, and stability to evaluate the severity of UC, which may provide potential application in clinical practice. Registration: This clinical trial was registered at the ClinicalTrials.gov (trial registration number: NCT05336773) Plain language summary: Why was this study done? The development of an auxiliary diagnostic tool can reduce the workload of endoscopists and achieve rapid assessment of ulcerative colitis (UC) severity. What did the researchers do? We developed and validated a deep learning-based approach to automatically predict the Mayo endoscopic score using UC endoscopic images. What did the researchers find? The model that was developed in this study achieved high accuracy, fidelity, and stability, and demonstrated potential application in clinical practice. What do the findings mean? Deep learning could effectively assist endoscopists in evaluating the severity of UC in patients using endoscopic images. [ABSTRACT FROM AUTHOR]

Several studies have shown the importance of electromagnetic ion cyclotron (EMIC) rising‐tone emissions to the rapid precipitation of energetic radiation belt electrons. Based on a large number of Van Allen Probes observations from October 2012 to July 2019, we identify EMIC rising‐tone emissions using a convolutional neural network (CNN), a modern deep learning technique. Results of training indicate that the CNN is capable of identifying EMIC rising‐tone emissions with a recall of 99.3%. The statistical analysis of the wave events identified reveals that the average occurrence rate of the events is about 0.016%, with a high occurrence rate from the forenoon to the dusk sector at L > 5. There are also events observed at L < 5, which are scattered at almost all magnetic local times. The events in the hydrogen and helium bands have comparable wave amplitudes on average, but the larger amplitude events tend to occur around noon and in the afternoon sector in the hydrogen and helium bands, respectively. In addition, the frequency sweep rate tends to increase with the wave frequency. The frequency sweep rates of the hydrogen band EMIC rising‐tone emissions are about 6 times larger than those of the helium band events. There is also a positive correlation between the wave amplitudes and the sweep rates of the hydrogen band emissions. Plain Language Summary: Electromagnetic ion cyclotron (EMIC) rising‐tone emissions can cause efficient proton scattering and rapid precipitation of radiation belt electrons. A convolutional neural network (CNN) is constructed to automatically identify EMIC rising‐tone emissions from about 7 years of measurements by Van Allen Probes. 99.3% of the EMIC rising‐tone emissions in the testing set are correctly classified by the CNN. The statistical analysis of the EMIC rising‐tone emission events identified shows that EMIC rising‐tone emissions were observed for 0.016% of the satellite dwell time. The emissions mainly occur from the forenoon to the dusk sector at L > 5. Different from previous studies, there are also EMIC rising‐tone emissions observed at L < 5, which are scattered at almost all magnetic local times. The peak amplitude of the hydrogen band emissions appears at noon, and the peak amplitude of the helium band emissions appears in the afternoon sector. In addition, our analysis demonstrates a positive correction between the frequency sweep rate and the wave frequency for the emissions in both the hydrogen and helium bands. The sweep rate also clearly increases with the wave amplitude for the hydrogen band emissions. Both trends agree with the nonlinear wave growth theory of EMIC rising‐tone emissions. Key Points: A convolutional neural network is constructed to identify electromagnetic ion cyclotron rising‐tone emissions in Van Allen Probes observationsThe waves have a high occurrence rate from the forenoon to the dusk sector at L > 5 and are more uniformly distributed in magnetic local time at L < 5Statistical results of the wave sweep rates are in general agreement with the nonlinear wave growth theory [ABSTRACT FROM AUTHOR]

An optimal meeting point query is used to determine a location in a spatial region to build a new facility that minimizes the sum of the (weighted) road distances from all clients. This problem has been studied in previous work with the assumption that all clients and facilities reside in Euclidean space or along road networks. However, due to the limitations of geographic information system technologies, it is difficult to return an exact geographic location to answer the optimal meeting point query based on a set of arbitrary coordinates. This issue results in various problems, such as positioning and measurement errors, in practical use. In this paper, it is aimed to identify the optimal meeting point in road networks for clients and facilities residing in non‐Euclidean spaces. Two efficient heuristic solutions are proposed based on approximate and adaptive query processing techniques by using randomized adaptive search and random direction search methods, respectively, to rapidly converge to the global optimum in the geographic coordinate system. Extensive experiments based on real datasets demonstrate that our proposed method achieves a 32.11% improvement over the state‐of‐the‐art approach. [ABSTRACT FROM AUTHOR]

When assessing the scattering of radiation belt electrons by fast magnetosonic (MS) waves, it is traditionally assumed that the waves follow the MS/whistler branch of the cold plasma dispersion relation (CPDR) in magnetohydrodynamics. However, MS waves are essentially ion Bernstein modes following a distinct kinetic dispersion relation. This study calculates the MS wave‐induced electron diffusion rates with the kinetic dispersion relation for the first time and compares the results with that obtained with the CPDR. It is found that the kinetic effects lead to a lower minimum resonant energy around 100 eV and a broader resonant pitch angle range. Kinetic effects also result in power spectral density attenuation when transforming wave frequency spectra into wavenumber spectra, so the diffusion rates are overall smaller than the ones obtained using the CPDR. Our results demonstrate that kinetic effects can significantly affect the role that MS waves play in the radiation belt dynamics. Plain Language Summary: Magnetosonic (MS) waves belong to the kinetic ion Bernstein modes essentially. But when the cold plasma is dominating, the waves also approximately follow the MS/whistler branch of the cold plasma dispersion relation (CPDR) in magnetohydrodynamics. Subsequently, studies of the electron scattering by MS waves have traditionally assumed the CPDR for simplicity. Motivated by recent studies which involved both satellite observations and kinetic theory revealing that the lower harmonic MS waves clearly follow the kinetic dispersion relation, we assess how the differences between the kinetic and cold plasma dispersion relations affect the MS wave‐induced electron scattering rates. Our results indicate that the kinetic dispersion relation produces relatively lower parallel phase speeds for MS waves, leading to a lower minimum resonant energy and subsequently a broader resonant pitch angle range for electrons (of a given energy). The kinetic effects also decrease the overall diffusion rates by attenuating the wave power spectral density in wavenumber space when mapped from a given frequency spectrum. Key Points: Linear kinetic dispersion relation indicates lower phase speeds and a broader range of group speeds for fast magnetosonic (MS) wavesThe lower phase speeds of MS waves result in a broader range of resonant pitch angles and lower minimum resonant energies of electronsKinetic effects reduce the wavenumber power spectral density and thus result in smaller electron diffusion rates [ABSTRACT FROM AUTHOR]

The rapid development of mobile computing (e.g., mobile health, mobile payments, and smart homes) has brought great convenience to our lives. It is well-known that the security and privacy of user information from these applications and services is critical. Without the prevention provided by an authentication mechanism, safety vulnerabilities may accumulate, such as illegal intrusion access resulting in data leakage and fraudulent abuse. Luckily, the two-factor authentication (2FA) protocols can secure access and communication for mobile computing. As we understand it, existing 2FA authentication protocols weaken security in the pursuit of high efficiency. How efficiency can be achieved while preserving the protocol's security remains a challenge. In this study, we designed a robust and effective 2FA protocol based on elliptic curve cryptography (ECC) for authentication of users and service providers. We proved the robustness (respectively, the effectiveness) of the presented protocol with the heuristic analysis and security verification provided by the ProVerif tool (respectively, with a performance comparison based on six schemes). Performance comparisons in terms of message rounds, communication, and computation overheads showed that our scheme was superior to the exiting schemes or comparable as a whole; i.e., only two rounds, 1376 bits, and 1.818 ms were required in our scheme, respectively. The evaluation results showed that the proposed 2FA protocol provides a better balance between security and availability compared to state-of-the-art protocols. [ABSTRACT FROM AUTHOR]

We proposed an optical frequency domain reflectometry based on a multilayer perceptron. A classification multilayer perceptron was applied to train and grasp the fingerprint features of Rayleigh scattering spectrum in the optical fiber. The training set was constructed by moving the reference spectrum and adding the supplementary spectrum. Strain measurement was employed to verify the feasibility of the method. Compared with the traditional cross-correlation algorithm, the multilayer perceptron achieves a larger measurement range, better measurement accuracy, and is less time-consuming. To our knowledge, this is the first time that machine learning has been introduced into an optical frequency domain reflectometry system. Such thoughts and results would bring new knowledge and optimization to the optical frequency domain reflectometer system. [ABSTRACT FROM AUTHOR]

Hybrid simulations are carried out to study the instabilities driven by the outer heliosheath pickup ions of ring-beam velocity distributions. Following the linear instability analysis in the companion paper, the electromagnetic instabilities at various propagation directions (0° ≤ θ ≤ 180°) are studied for pickup ion ring-beam distributions of different pickup angles (0° ≤ α ≤ 90°). Previous studies of the ring-beam pickup ion distributions have been limited to the parallel- and antiparallel-propagating modes (θ = 0° and 180°). In this paper, several one-dimensional hybrid simulations are performed to investigate the most unstable modes of different propagation angles predicted by the linear instability analysis. Moreover, two-dimensional hybrid simulations are conducted to examine the simultaneous excitation of the parallel, antiparallel, and oblique unstable modes and their role in the scattering of the outer heliosheath pickup ions. Our recent one-dimensional hybrid and particle-in-cell simulations with simulation domains along the background magnetic field demonstrated that at small pickup angles, the outer heliosheath pickup ions experience an incomplete scattering limited to the hemisphere of positive parallel velocities with respect to the background magnetic field. In contrast, the present two-dimensional hybrid simulation results show that when both parallel/antiparallel and oblique unstable modes are acting together, the pickup ions can be scattered into the hemisphere of negative parallel velocities and approach a near-isotropic velocity distribution. This is in conflict with the spatial retention scenario of the energetic neutral atom ribbon observed by the Interstellar Boundary Explorer, which requires pickup ions at small pickup angles to stream away from the ribbon directions. [ABSTRACT FROM AUTHOR]

The energetic neutral atom ribbon observed by the Interstellar Boundary Explorer spacecraft is believed to originate from the pickup ions in the outer heliosheath. The outer heliosheath pickup ions generally have a ring-beam velocity distribution at a certain pickup angle, α, the angle at which these ions are picked up by the interstellar magnetic field. The pickup ion ring-beam distributions can drive unstable waves of different propagation angles with respect to the background interstellar magnetic field, θ. Previous studies of the outer heliosheath pickup ion dynamics were mainly focused on ring-like pickup ion distributions with α ≈ 90° and/or the parallel- and antiparallel-propagating unstable waves (θ = 0° and 180°). The present study carries out linear kinetic instability analysis to investigate both the parallel and oblique unstable modes (0° ≤ θ ≤ 180°) driven by ring-beam pickup ion distributions of different pickup angles between 0° and 90°. Our linear instability analysis reveals that ring-beam pickup ion distributions can excite oblique mirror waves as well as parallel/quasi-parallel and oblique right- and left-helicity waves. The maximum growth rate among all the instabilities belongs to the parallel-propagating left-helicity waves at most pickup angles. Furthermore, the evolution of the unstable mirror waves by varying pickup angle indicates that as the pickup angle increases, the maximum growth rate of the mirror modes increases, while its propagation angle decreases. [ABSTRACT FROM AUTHOR]

Recently, with the increase in the market share of the Android system and the sharp increase in the number of Android mobile apps, many countries and regions have successively launched laws and regulations related to data security. The EU's GDPR and China's Information Security Technology-Personal Information Security Specification are two of the most important bills, affecting vast areas and large populations. Both regulations impose requirements on privacy policy specifications for Android apps. With these requirements, however, apps' privacy policies have become larger. Researchers have conducted studies on whether the actual privacy behavior of apps conforms to their privacy policy description but have not focused on compliance with the privacy policy itself. In this paper, we propose evaluation metrics for privacy policy compliance and evaluate popular apps by analyzing privacy policies and apps. We applied our method to 1,000 apps from the Google Play Store in Europe and 1,000 apps from the Tencent Appstore in China. We detected a number of app privacy policy noncompliance issues and discovered a number of privacy issues with third-party services and third-party libraries. [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2009.05.015 Byline: Esa Kallio (a)(b), Kaijun Liu (a), Riku Jarvinen (a), Valter Pohjola (a), Pekka Janhunen (a) Keywords: Mars; Planetary ionospheres; Planetary magnetospheres; Numerical modelling; Hybrid model Abstract: We have studied the escape and energization of several O.sup.+ populations and an O.sub.2.sup.+ population at Mars by using a hybrid model. The quasi-neutral hybrid model, HYB-Mars model, included five oxygen ion populations making it possible to distinguish photoions from oxygen ions originating from charge exchange processes and from the ionosphere. We have identified two high-energy ion components and one low-energy ion component of oxygen. They have different spatial and energy distributions near Mars. The two high-energy oxygen ion components, consisting of a high-energy 'beam' and a high-energy 'halo', have different origins. (1) The high-energy (>[approximately equal to]100eV) 'beam' of O.sup.+ and O.sub.2.sup.+ ions are originating from the ionosphere. These ions form a highly asymmetric spatial distribution of escaping oxygen ions with respect to the direction of the convective electric field in the solar wind. (2) The high-energy (>[approximately equal to]100eV) 'halo' component contains O.sup.+ ions which are formed from the oxygen neutral exosphere by extreme ultraviolet radiation (EUV) and by charge exchange processes. These energetic halo ions can be found all around Mars. (3) The low energy O.sup.+ and O.sub.2.sup.+ ions ( The existence of the low- and the high-energy oxygen components is in agreement with recent in situ plasma measurements made by the ASPERA-3 instrument on the Mars Express mission. The analysis of the escaping oxygen ions suggests that the global energization of escaping planetary ions in the martian tail is controlled by the convective electric field. Author Affiliation: (a) Finnish Meteorological Institute, Helsinki, Finland (b) University of Helsinki, Department of Physics, Helsinki, Finland Article History: Received 15 November 2008; Revised 31 March 2009; Accepted 11 May 2009

Scattering of pickup ion ring-beam distributions in the outer heliosheath is a fundamental element in the spatial retention scenario of the energetic neutral atom (ENA) ribbon observed by the Interstellar Boundary EXplorer (IBEX). According to our earlier linear instability analysis, pickup ion ring-beam distributions trigger magnetic field-aligned, right-hand polarized unstable waves in two separate frequency ranges which are near and far above the proton cyclotron frequency, respectively. We have performed hybrid simulations to study the unstable waves near the proton cyclotron frequency. However, the high-frequency waves well above the proton cyclotron frequency are beyond the reach of hybrid simulations. In this paper, particle-in-cell simulations are carried out to study the parallel- and antiparallel-propagating high-frequency waves excited by the outer heliosheath pickup ions at different pickup angles as well as the scattering of the pickup ions by the waves excited. In the early stages of the simulations, the results confirm the excitation of the parallel-propagating, right-hand polarized high-frequency waves as predicted by the earlier linear analysis. Later in the simulations, enhanced antiparallel-propagating modes also emerge. Furthermore, the evolution of the pickup ion ring-beam distributions of the selected pickup angles reveals that the high-frequency waves do not significantly contribute to the pickup ion scattering. These results are favourable regarding the plausibility of the spatial retention scenario of the IBEX ENA ribbon. [ABSTRACT FROM AUTHOR]

Background: The tumor immune microenvironment (TIME) phenotypes have been reported to mainly impact the efficacy of immunotherapy. Given the increasing use of immunotherapy in cancers, knowing an individual's TIME phenotypes could be helpful in screening patients who are more likely to respond to immunotherapy. Our study intended to establish, validate, and apply a machine learning model to predict TIME profiles in non-small cell lung cancer (NSCLC) by using 18F-FDG PET/CT radiomics and clinical characteristics. Methods: The RNA-seq data of 1145 NSCLC patients from The Cancer Genome Atlas (TCGA) cohort were analyzed. Then, 221 NSCLC patients from Daping Hospital (DPH) cohort received18F-FDG PET/CT scans before treatment and CD8 expression of the tumor samples were tested. The Artificial Intelligence Kit software was used to extract radiomic features of PET/CT images and develop a radiomics signature. The models were established by radiomics, clinical features, and radiomics-clinical combination, respectively, the performance of which was calculated by receiver operating curves (ROCs) and compared by DeLong test. Moreover, based on radiomics score (Rad-score) and clinical features, a nomogram was established. Finally, we applied the combined model to evaluate TIME phenotypes of NSCLC patients in The Cancer Imaging Archive (TCIA) cohort (n = 39). Results: TCGA data showed CD8 expression could represent the TIME profiles in NSCLC. In DPH cohort, PET/CT radiomics model outperformed CT model (AUC: 0.907 vs. 0.861, P = 0.0314) to predict CD8 expression. Further, PET/CT radiomics-clinical combined model (AUC = 0.932) outperformed PET/CT radiomics model (AUC = 0.907, P = 0.0326) or clinical model (AUC = 0.868, P = 0.0036) to predict CD8 expression. In the TCIA cohort, the predicted CD8-high group had significantly higher immune scores and more activated immune pathways than the predicted CD8-low group (P = 0.0421). Conclusion: Our study indicates that 18F-FDG PET/CT radiomics-clinical combined model could be a clinically practical method to non-invasively detect the tumor immune status in NSCLCs. [ABSTRACT FROM AUTHOR]

As the SCADA system develops continuously, the dissemination of malicious network behaviors has brought great risk to the normal operation of enterprises, meanwhile resulting in huge economic burden to personal work and life. Therefore, the security reinforcement strategy is crucial to the field of network security management and analysis of the SCADA system. Some researchers have started to investigate on how to minimize the cost of realizing the SCADA system reinforcement strategy. However, the SCADA system administrators are facing a very challenging problem, that's the reinforcement budget is less than the minimal input of SCADA system security reinforcement. The core of this problem lies on how to choose a subset from massive security reinforcement strategies, so as to minimize the risks from not patching all essential security vulnerabilities within the budget. Based on a deep comparative analysis of existing multi-objective optimization technologies, this paper proposes a multi-objective optimization method based on system attack tree model, and uses Pareto algorithm to solve this problem. The experimental results demonstrate that the Pareto algorithm can effectively make the multi-objective decision in security reinforcement strategy, and can solve practical issues in actual SCADA system security reinforcement practice. [ABSTRACT FROM AUTHOR]

Customized bus is a typical demand‐responsive transit (DRT) service that allows passengers to customize their bus route on demand and be picked up and dropped off at their desired location. A set of ride requests sent at various times by geographically dispersed passengers are operated in real time by the controller and then assigned to the shared bus with the assurance of maintaining the minimum vehicle and driver costs, which introduces a new challenge to scheduling. In this paper, a mixed integer linear programming (MILP) model is presented to solve the customized bus scheduling problem. To quickly generate satisfactory scheduling solutions in the case of single‐ and multi‐depots, a heuristic multi‐objective optimization algorithm based on preemptive scheduling is proposed, which can converge to the optimal solution among a set of vehicle blocks (consecutive trips by one bus). A real‐world customized bus scheduling problem from the public transport company of Chengdu, China that contains 2,000‐trip instances operated on a day is used to demonstrate that the proposed approach reduces total operating costs by 30.51% and 30.71%, compared with the simulated annealing algorithm and genetic algorithm, respectively. [ABSTRACT FROM AUTHOR]

We report the first statistical survey of the oxygen ion cyclotron harmonic waves observed by Van Allen Probes throughout the mission. Our statistical study shows that the waves occurred over 2 < L < 6 and across all magnetic local time. More than 50% of the events were observed just outside the plasmapause, and the typical wave amplitude is between ∼0.1 and several nT. The frequency spacing between two consecutive wave harmonics decreases with increasing L but stabilizes when L > 5. The frequency spacing is larger than the local oxygen ion gyrofrequency for many events, especially those observed at larger L, suggesting that these waves propagated there from lower L shell regions. The waves are mainly on the dayside at L > 4 under quiet geomagnetic conditions, but can occur at lower L shells with a more uniform MLT distribution under more active geomagnetic conditions. Plain Language Summary: As their name suggests, oxygen ion cyclotron harmonic (OCH) waves have discrete spectral peaks near multiple harmonics of the oxygen ion cyclotron frequency. These waves have been observed in the terrestrial magnetosphere but have not been thoroughly studied. Their excitation mechanism and propagation direction are still under debate. In this study, we perform the first statistical survey of these waves based on Van Allen Probes observations. An example event first demonstrates the general properties of typical OCH waves. The corresponding ion distribution suggests that the waves are excited by energetic oxygen ions with a ring‐like partial shell velocity distribution and can lead to the transverse heating of helium and oxygen ions less than a few hundred eV. Our statistical results show that the waves occurred in a large area while their spatial distribution varies with the geomagnetic activity level. Interestingly, the frequency spacing between two consecutive discrete spectral peaks tends to be smaller for the waves observed further away from the Earth and is mostly larger than the local oxygen ion gyrofrequency. Thus, many of the waves are probably not locally generated but have propagated there from lower altitudes. Key Points: We report the first statistical study of the oxygen ion cyclotron harmonic waves observed by Van Allen Probes throughout the missionThe waves occurred over 2 < L < 6 and across all magnetic local time. Over 50% of the events were observed just outside the plasmapauseThe frequency spacing between wave harmonics decreases with increasing L and is mostly larger than the local oxygen ion gyrofrequency [ABSTRACT FROM AUTHOR]

One-dimensional hybrid simulations are performed to investigate the plasma instabilities driven by the pickup ions in the outer heliosheath, which are believed to have a ring-beam velocity distribution in general. The modes propagating parallel and antiparallel to the background magnetic field are studied for pickup ion ring-beam distributions of different pickup angles, following the linear kinetic instability analysis presented in our previous work. The simulation results first confirm the unstable modes predicted by the linear analysis and further reveal how the pickup ions are scattered by the excited waves. While the maximum growth rate of the low-frequency, left-helicity waves occurs at the pickup angle of 82° (consistent with the linear analysis results), the saturation level of the fluctuating magnetic field is the highest around 45° pickup angle. For the pickup ion parameters examined, the pitch-angle spread of the pickup ions at the end of the simulations decreases with increasing pickup angle. Our study goes beyond previous studies of the pickup-ion-driven instabilities in the outer heliosheath which mainly focused on ring-like distributions of around 90° pickup angle. With the caveats that the pickup ion parameters are in the Alfvén cyclotron stability gap and that the one-dimensional simulations only include parallel and antiparallel-propagating modes, our results show that the scattering of pickup ions at small pickup angles is limited to one hemisphere so they can drift away from the ribbon direction as required by the spatial retention scenario of the energetic neutral atom ribbon observed by the Interstellar Boundary EXplorer. [ABSTRACT FROM AUTHOR]

Although some plasma waves exhibit the largest growth rate and amplitude at 90° wave normal angle (WNA), particle scattering by these waves in a quasilinear (QL) sense has seldom been examined previously. Using test‐particle calculation and QL theory and assuming a uniform background magnetic field, the present study investigates the proton scattering by equatorial fast magnetosonic waves (MSWs; a.k.a equatorial noise) with varying WNAs including 90°. Comparison with the diffusion coefficients in momentum space obtained from the test‐particle approach indicates that the QL diffusion coefficients due to MSWs are consistent with those estimated from the test‐particle method up to 90° WNA, provided that MSWs described conform to the usual QL theory assumptions. The test‐particle dynamics due to MSWs at 90° WNA are examined in detail. Although in the QL picture, perpendicularly propagating MSWs are only supposed to resonate with protons at integer harmonic frequencies, waves at slightly off‐integer harmonic frequencies as part of a narrowband discrete spectrum of incoherent MSWs play an important role in making the proton scattering stochastic. Considering the recent test‐particle result of bounce‐averaged resonance of energetic protons, non‐zero wave power at the WNAs ≳89.5° typically excluded in QL diffusion can be important for ring current proton dynamics. Key Points: Quasilinear diffusion coefficients of protons scattered by magnetosonic waves (MSWs) at quasi‐perpendicular propagation are calculatedProton dynamics due to MSWs at perpendicular propagation are examined in detail using test‐particle tracingNon‐zero wave power at ≳89.5° wave normal angles typically excluded can be important for ring current proton dynamics [ABSTRACT FROM AUTHOR]

The electromagnetic instabilities driven by the pickup ions in the outer heliosheath play a crucial role in interpreting the energetic neutral atom (ENA) ribbon observed by the Interstellar Boundary EXplorer (IBEX). Previous studies on the stability of the outer heliosheath pickup ions focused on ring-like velocity distributions with pickup angles equal or close to 90°. In this study, we investigate the instabilities driven by a ring-beam velocity distribution of the pickup ions in the outer heliosheath using linear instability analysis. The modes propagating along (both parallel and antiparallel to) the background magnetic field are examined, and the emphasis is on how the instabilities change with the pickup angle, α, varying from zero to 90°. The parallel thermal spread of the pickup ions is chosen to make the plasma parameters lie in the Alfvén cyclotron 'stability gap' to exclude the well-studied Alfvén cyclotron instability. Our linear instability analysis reveals that the unstable modes all have left helicity but may propagate parallel or antiparallel to the background magnetic field. At small α, the parallel-propagating modes are unstable in two separate wavenumber (and frequency) ranges. The two unstable ranges merge into one when α increases to 82°. In addition, the antiparallel-propagating modes become unstable when α is above 5°, but the parallel-propagating modes have larger growth rates until α becomes larger than αc = 82.8°. The growth rates of the parallel-propagating modes quickly drop below zero when α goes beyond αc, while the antiparallel-propagating modes remain unstable until α approaches 90°. [ABSTRACT FROM AUTHOR]

It is generally believed that the top centimeters of mature lunar regolith should be dominated by fine particles that contain few rocky fragments, but surface fragments are occasionally visible in mature lunar regolith. Based on amplitudes of surface echoes received by the Lunar Penetrating Radar onboard the Yutu‐2 rover of the Chang'E‐4 mission, we extracted regions with abnormally high relative permittivity that is larger than 4, quantifying the abundance of dense fragments within the top ∼4 cm of the mature regolith along the rover path. We carried out high‐resolution numerical simulations for the propagation of electromagnetic waves, showing that the abnormally high relative permittivity is not caused by local topography but due to the existence of dense materials. Using high‐resolution images obtained by the panorama camera onboard the rover, we performed correlated observation for areas with abnormally high relative permittivity, confirming that some of these dense materials are exposed rocky fragments. However, most of the high relative permittivity areas are not correlated with surface fragments, and some are located beneath floors of highly degraded small impact craters. We found that regolith clumps formed due to impact compaction are not dense enough to cause the abnormally large relative permittivity. Alternatively, the detected dense materials may be melt‐bearing impact breccias in the shallow regolith, which were formed by the host craters. The results revealed a highly heterogeneous structure at shallow depths of mature lunar regolith, revealing a new mechanism of sand‐blasting impacts on the destruction of pores in mature lunar regolith. Plain Language Summary: Interior structures of lunar regolith record important information about the surface dynamics on the Moon. It has been noticed that vertical and lateral heterogeneities widely exist in lunar regolith. However, the possible abundance of rocky fragments in mature regolith (e.g., those in the top few centimeters) is not well constrained. Resolving this issue is important for the understanding of regolith formation. The Chang'E‐4 mission provides an excellent opportunity to study the interior structures of mature lunar regolith. The landing area is covered by ∼12‐ m‐thick regolith, and the surface regolith has a high optical maturity index with few visible surface fragments. In this work, we detect the abundance of rock materials within a depth of ∼4 cm in the mature regolith along the path of Yutu‐2, based on a combination of photogeology observation and numerical modeling. We found that the spatial distribution of rock materials in the shallow regolith is highly heterogenous, and >1/4 of the detected dense materials are located beneath small and degraded impact craters, where no fragments are visible on the surface. The results indicate that by producing melt‐welded impact breccia, small impacts formed in mature regolith could substantially reduce the porosity of local regolith. Key Points: Relative permittivity (ε) of the top ∼4‐ cm‐thick mature regolith is derived along the Yutu‐2 path at the Chang'E‐4 landing areaSome high permittivity areas along the path of Yutu‐2 are linked to exposed boulders while others probably feature buried rock fragmentsSand‐blasting impacts on the Moon can decrease the porosity of lunar regolith by compaction and melt welding [ABSTRACT FROM AUTHOR]