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A technique for estimating the velocity of radio meteors is proposed. The presented method is based on the analysis of the phase of the Fourier spectra of complex amplitudes of signals reflected from meteor trails. The method is very fast compared to the Fresnel transform method, works at low signal-to-noise ratios and is automatic. Approaches for increasing the signal-to-noise ratio and criteria for rejecting the obtained estimates are proposed. An error of 1–10% was achieved, depending on the signal-to-noise ratio (from −5 dB) and the velocity of the meteor. Comparison of meteoroid velocities from Kazan Federal University meteor radar measurements with optical observations showed good agreement of estimates with a slight underestimation of 2–8%, presumably due to the neglect of deceleration. [ABSTRACT FROM AUTHOR]

This study discusses historical records of Korea that mention "stars" possibly related to astronomical transient events. We selected 19 such records and scrutinized them by cross‐checking with records of other countries to identify those events. Ten events were identified as comets based on their described motions and tails. We further confirmed this by comparing them with records from other countries. Five events were classified as meteors based on descriptions of their movements, sizes, and shapes. We speculate that two recordings about "big stars" (大星) are typographical errors for "Mars" (火星), as the descriptions of these big stars seem to be consistent with the properties of the latter. This leaves two unidentified events, and we search lists of astronomical transients for their counterparts. Our work emphasizes the uncertainties and challenges caused by the limited information in the historical records while exploring the usefulness of historical records to enhance the understanding of astrophysical transient events. [ABSTRACT FROM AUTHOR]

Infrasound sensing plays a critical role in the detection and analysis of bolides, offering passive, cost-effective global monitoring capabilities. Key objectives include determining the timing, location, and yield of these events. Achieving these goals requires a robust approach to detect, analyze, and interpret rapidly moving elevated sources such as bolides (also re-entry). In light of advancements in infrasonic methodologies, there is a need for a comprehensive overview of the characteristics that distinguish bolides from other infrasound sources and methodologies for bolide infrasound analysis. This paper provides a focused review of key considerations and presents a unified framework to enhance infrasound processing approaches specifically tailored for bolides. Three representative case studies are presented to demonstrate the practical application of infrasound processing methodologies and deriving source parameters while exploring challenges associated with bolide-generated infrasound. These case studies underscore the effectiveness of infrasound in determining source parameters and highlight interpretative challenges, such as variations in signal period measurements across different studies. Future research should place emphasis on improving geolocation and yield accuracy. This can be achieved through rigorous and systematic analyses of large, statistically significant samples of such events, aiming to resolve interpretative inconsistencies and explore the causes for variability in signal periods and back azimuths. The topic described here is also relevant to space exploration involving planetary bodies with atmospheres, such as Venus, Mars, and Titan. [ABSTRACT FROM AUTHOR]

Meteor speed is crucial in identifying key astronomical aspects of the meteoroid environment, including the influx of meteoric material and the distribution of meteoric radiants. This study investigates diurnal and seasonal variations of meteor speed from April 2014 to December 2023 observed by the Mengcheng meteor radar (MCMR; 33.4°N, 116.3°E). In addition to the expected diurnal variation of meteor speed, azimuth peak, zenith peak, and the azimuthal direction of maximum meteor speed due to the Earth's rotation, where the meteor speed peaks northward in the local morning and shifts clockwise, we find that the meteor speed distribution resembles a superposition of two Gaussian distributions, with the lower (higher) distribution mainly ranging from 20 to 40 (45–65) km/s. The two speed peaks are estimated using a double‐Gaussian fitting approach. In terms of seasonal variation, we find that (a) the low‐speed peak indicates a semi‐annual variation cycle, with maxima in June–July and December–January, and minima in February and August; (b) the high‐speed peak indicates an annual variation cycle, with maxima in September–December and minima in March. There is also a correlation between the seasonal variations in the meteor speed peaks and the occurrence of meteor showers. Statistical analysis provides a map of seasonal variations in the intensity, duration, and timing of meteor shower activities, which is supplemental to previous shorter‐duration studies using backscatter meteor radar observations. We also find notable shower events where the meteor counts exceed 45%–97% of the background count on corresponding event dates and speeds. Plain Language Summary: Meteor speed plays a crucial role in understanding the quantity and distribution of meteoroids in our environment, yet there are limited observations and investigations conducted at mid‐latitudes. In this study, we utilized a meteor radar located in Mengcheng (in the northern lower middle latitudes) to investigate diurnal and seasonal variations in meteor speed from April 2014 to June 2023. Our findings revealed that meteor speed is generally faster in the morning and slower in the afternoon and evening, and the angle of arrival of meteors varies with local time. Additionally, we discovered that meteor speed exhibits two peaks, with the lower one at about 28 km/s and the higher one at 54 km/s. Seasonal changes indicated a semi‐annual variation cycle in the low‐speed peak and an annual variation cycle in the high‐speed peak. Furthermore, we observed several noteworthy meteor showers and their interannual variations. Key Points: The meteor speed peaks northward in the local morning and shifts clockwise to southward by local eveningMeteor speed distribution has two Gaussian peaks at ∼28 and ∼54 km/s, revealing semi‐annual and annual variation cycles respectivelyMajor meteor showers occur with 45%–97% higher counts than the background, and are associated with increases in the peak speeds [ABSTRACT FROM AUTHOR]

Translating the Holy Quran into different languages is a crucial task. It is a daunting one, given the linguistic complexity and rich cultural context of this holy scripture. The recent advancements in technology, especially in artificial intelligence, brought about a pressing need to explore the potential of machine learning-based tools in easing the translation of religious texts, the Holy Quran in particular. This study explores the potential of adopting ChatGPT, a large language model (LLM) powered by machine learning, in English Quranic translation. The study aims to assess the accuracy, adequacy, and cultural sensitivity of ChatGPT's English Quranic translation and identify potential challenges and limitations of using this tool in this domain. The study employed a comparative analysis approach, evaluating ChatGPT's translation of the El Fatiha Chapter against five humangenerated translations using BLEU (Bilingual Evaluation Understudy) and METEOR (Metric for Evaluation of Translation with Explicit ORdering) machine translation metrics. The study also utilized an interpretation of the chapter by El Qurtubi to ensure that ChatGPT has the entire linguistic and cultural context of the chapter. The study's findings indicated that ChatGPT's English translation of El Fatiha achieved a moderate level of accuracy and adequacy with mean BLEU and METEOR scores of 0,48 and 0,78, respectively. However, there were areas where ChatGPT's translation could be improved. The use of ML-based tools such as ChatGPT in English Quranic translation offers promising benefits as it can aid translators in the translation process. [ABSTRACT FROM AUTHOR]

• Evaluated the performance of various dissimilarity criteria and distance metrics for meteor association with CAMS database, as well as computed their optimal thresholds. • The sEuclidean metric excels in meteor shower association and identifying sporadic meteors, with D SH and ϱ 2 closely behind, the latter showing the closest equivalence to Machine Learning metrics. • Machine Learning distance metrics demonstrate their potential to match or even surpass tailored orbital similarity criteria in meteor dynamical associations. Meteor showers, originating as a result of the activity of comets or the disruption of large objects, provide a unique window into the composition and dynamics of our Solar System. While modern meteor detection networks have amassed extensive data, distinguishing sporadic meteors from those belonging to specific meteor showers remains challenging. In this study, we statistically evaluate and compare four orbital similarity criteria within five-dimensional parameter space ( D SH , D D , D H , and ϱ 2 ) to study dynamical associations using the already classified meteors (manually by a human) in CAMS database as a benchmark. In addition, we assess various distance metrics typically used in Machine Learning with two different vectors: ORBIT, grounded in heliocentric orbital elements, and GEO, predicated on geocentric observational parameters. To estimate their degree of correlation and efficacy, the Kendall rank correlation coefficient and the Top-k accuracy are employed. The statistical equivalence of the Top-1 results is examined using the Kolmogorov–Smirnov test and the percentage of Top-1 agreement is calculated on an event-by-event basis. Additionally, we compute the optimal cut-offs for all methods for distinguishing sporadic background events. Our findings demonstrate the superior performance of the sEuclidean metric in conjunction with the GEO vector. Within the scope of D-criteria, D SH emerged as the preeminent metric, closely followed by ϱ 2 . The Bray-Curtis metric displayed an advantage compared to the other distance metrics when paired with the ORBIT vector for Top-k accuracy, however, the Cityblock metric is more effective when considering the sporadic background. ϱ 2 stands out as the most equivalence to the distance metrics when utilizing the GEO vector and the most compatible with GEO and ORBIT simultaneously, whereas D D aligns more closely when using the ORBIT vector. The stark contrast in D D 's behavior compared to other D-criteria highlights potential inequivalence. Our results suggest that geocentric features provide a more robust basis than orbital elements for meteor dynamical association. Most distance metrics associated with the GEO vector surpass the D-criteria when differentiating the meteoroid background. Accuracy displayed a dependence on solar longitude with a pronounced decrease around 180 ° matching an apparent increase in the meteoroid background activity, tentatively associated with the transition from the Perseids to the Orionids. Considering lately identified meteor showers, ∼ 27% of meteors in CAMS would have different associations. This work unveils that Machine Learning distance metrics can rival or even exceed the performance of tailored orbital similarity criteria for meteor dynamical association. [ABSTRACT FROM AUTHOR]

Meteoroids entering the Earth's atmosphere lose most of their mass during atmospheric passage and considerably disturb the background ionosphere. To elucidate better the effects of meteoroids on the near-Earth space environment, it is important to simultaneously observe various meteoroids and their related phenomena in the Earth's atmosphere. This study briefly describes a newly developed Meteor and ionospheric Irregularity Observation System (MIOS), which consists of a phased-array radar, a bi-static all-sky radar, and a multi-station optical imaging and spectroscopy subsystem. The MIOS can capture the processes of ablation and evaporation of meteoroids, creating luminous and ionization trails, and measure the properties of both the meteor trail and its corresponding meteoroid within a large field of view. Based on the MIOS, some observational modes and data processing methods have been developed, where the physical and chemical properties of meteoroids (including their velocity, mass, composition, and source region), meteor plasma head and trail irregularity and their structural evolution, and the instantaneous neutral wind can be obtained. Using the MIOS measurements, a preliminary study of some of the characteristics of meteoroids, meteor plasma head, meteor plasma trail field–aligned and non-field–aligned irregularities, meteor flare and dust trail irregularity, and ionospheric irregularity is presented.

Nirmatrelvir (NRV), a 3C‐like protease or Mpro inhibitor of SARS‐CoV‐2, is used for the treatment of COVID‐19 in adult and paediatric patients. The present study was accomplished to investigate the comprehensive metabolic fate of NRV using in vitro and in vivo models. The in vitro models used for the study were microsomes (human liver microsomes, rat liver microsomes, mouse liver microsomes) and S9 fractions (human liver S9 fractions and rat liver S9 fractions) with the appropriate cofactors, whereas Sprague–Dawley rats were used as the in vivo models. Nirmatrelvir was administered orally to Sprague–Dawley rats, which was followed by the collection of urine, faeces and blood at pre‐determined time intervals. Protein precipitation was used as the sample preparation method for all the samples. The samples were then analysed by liquid chromatography–quadrupole time‐of‐flight tandem mass spectrometry (LC‐Q‐ToF‐MS/MS) using an Acquity BEH C18 column with 0.1% formic acid and acetonitrile as the mobile phase. Four metabolites were found to be novel, which were formed via amide hydrolysis, oxidation and hydroxylation. Furthermore, an in silico analysis was performed using Meteor Nexus software to predict the probable metabolic changes of NRV. The toxicity and mutagenicity of NRV and its metabolites were also determined using DEREK Nexus and SARAH Nexus. [ABSTRACT FROM AUTHOR]

Copyright of Reviews of Geophysics & Planetary Physics is the property of Editorial Office of Reviews of Geophysics & Planetary Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In recent decades, the observation of the sky has experienced an exponential growth in amateur astronomical observatories, primarily based on high-sensitivity CCTV cameras capable of capturing the night sky, thereby highlighting the transit of meteors. Within this context, there are actual international networks of observatories capable of providing data on the detection of these luminous appearances. In Italy, one of the most active stations is the LTPA Observer Project, established in 2007, which is equipped to monitor the night sky daily and provide key data on astronomical recordings associated with the passage of meteoric bodies in orbit around the Sun, attracted by Earth's gravitational force. In this realm, the study of these events has led to the emergence of a new investigative technique associated with seismic prediction. The LTPA Observer Project and the Radio Emissions Project, two Italian scientific initiatives for studying visible atmospheric luminous phenomena and seismic precursors, have highlighted the need to understand if sometimes the observation of large fireballs can be associated with the occurrence of strong earthquakes, albeit in a temporal context. This study explores precisely this possibility, namely whether the appearance of large fireballs can be considered a new, previously unknown seismic precursor, and whether this meteoric activity could be linked to solar activity. [ABSTRACT FROM AUTHOR]

Infrasound sensing plays a critical role in the detection and analysis of bolides, offering passive, cost-effective global monitoring capabilities. Key objectives include determining the timing, location, and yield of these events. Achieving these goals requires a robust approach to detect, analyze, and interpret rapidly moving elevated sources such as bolides (also re-entry). In light of advancements in infrasonic methodologies, there is a need for a comprehensive overview of the characteristics that distinguish bolides from other infrasound sources and methodologies for bolide infrasound analysis. This paper provides a focused review of key considerations and presents a unified framework to enhance infrasound processing approaches specifically tailored for bolides. Three representative case studies are presented to demonstrate the practical application of infrasound processing methodologies and deriving source parameters while exploring challenges associated with bolide-generated infrasound. These case studies underscore the effectiveness of infrasound in determining source parameters and highlight interpretative challenges, such as variations in signal period measurements across different studies. Future research should place emphasis on improving geolocation and yield accuracy. This can be achieved through rigorous and systematic analyses of large, statistically significant samples of such events, aiming to resolve interpretative inconsistencies and explore the causes for variability in signal periods and back azimuths. The topic described here is also relevant to space exploration involving planetary bodies with atmospheres, such as Venus, Mars, and Titan.

This paper gives a full description of development of foreign air-to-air missiles in 2022. It pre-sents the latest advancement of AIM-9X, AIM-120, Modular Advanced Missile, ASRAAM, IRIS-T, FCAAM, Meteor, innovative missile technologies, R-37M, Astra BVRAAM, Turkish new air-to-air missiles. In the end, the paper summarizes the new development features of air-to-air missiles.

Mini-EUSO is a wide-angle fluorescence telescope that registers ultraviolet (UV) radiation in the nocturnal atmosphere of Earth from the International Space Station. Meteors are among multiple phenomena that manifest themselves not only in the visible range but also in the UV. We present two simple artificial neural networks that allow for recognizing meteor signals in the Mini-EUSO data with high accuracy in terms of a binary classification problem. We expect that similar architectures can be effectively used for signal recognition in other fluorescence telescopes, regardless of the nature of the signal. Due to their simplicity, the networks can be implemented in onboard electronics of future orbital or balloon experiments. [ABSTRACT FROM AUTHOR]

We present a machine-learning approach to detect and analyze meteor echoes (MADAME), which is a radar data processing workflow featuring advanced machine-learning techniques using both supervised and unsupervised learning. Our results demonstrate that YOLOv4, a convolutional neural network (CNN)-based one-stage object detection model, performs remarkably well in detecting and identifying meteor head and trail echoes within processed radar signals. The detector can identify more than 80 echoes per minute in the testing data obtained from the Jicamarca high power large aperture (HPLA) radar. MADAME is also capable of autonomously processing data in an interferometer mode, as well as determining the target's radiant source and vector velocity. In the testing data, the Eta Aquarids meteor shower could be clearly identified from the meteor radiant source distribution analyzed automatically by MADAME, thereby demonstrating the proposed algorithm's functionality. In addition, MADAME found that about 50 percent of the meteors were traveling in inclined and near-inclined circular orbits. Furthermore, meteor head echoes with a trail are more likely to originate from shower meteor sources. Our results highlight the capability of advanced machine-learning techniques in radar signal processing, providing an efficient and powerful tool to facilitate future and new meteor research. [ABSTRACT FROM AUTHOR]

Copyright of Aero Weaponry is the property of Aero Weaponry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The construction of the distribution of the flux density of meteor bodies over the celestial sphere is necessary for solving problems of meteor astronomy and others. To construct such distributions, experimental data on the coordinates of meteor radiants are needed. Meteor radars provide determination of the coordinates of the radiant in the presence of one transmitter and three spaced receivers. In this research, we are talking about ground-based meteor observations of the number of meteors using single-station meteor back-skatter radars as simpler than measurements of meteor radiants. In the 1950–80s in Kharkiv (Ukraine), active meteor radar research was carried out, both simple single-station and complex with remote points. The authors in the 1980s were participants in the meteor international program GLOBMET (Kashcheev, 1982; Roper, 1990). At that time, they modified an algorithm for calculating the flux density of meteor bodies over the heliocentric celestial sphere by number, range and velocity for radar observations with using single-station meteor backscatter. An algorithm was developed for dividing the celestial sphere into regions with a combination of "celestial" and "antenna" regions with a binding of a meteor to the antenna region in radar observations with a narrowly directed antenna without goniometr. This algorithm was applied to specific equipment for measuring the number of meteors by the Kharkiv Meteor Automated Radar System (MARS), 31.1 MHz. The correctness of the algorithm was confirmed by constructing the density distribution of the incident flux over the celestial sphere based on measurements in October-December 1989. The distributions are constructed using two methods for approximating the amplitude-time characteristics of signals. The results represent the experience of past years, which may be of interest as a scientific and technical solution. [ABSTRACT FROM AUTHOR]

Calculating meteoroid masses from photometric observations relies on prior knowledge of the luminous efficiency, a parameter that is not well characterized; reported values vary by several orders of magnitude. We present results from an experimental campaign to determine the luminous efficiency as a function of mass, velocity, and composition. Using a linear electrostatic dust accelerator, iron and aluminum microparticles were accelerated to v > 10 km/s and ablated, and the light production measured. The luminous efficiency of each event was calculated and functional forms fit for each species. For both materials, the luminous efficiency is lowest at low velocities, rises sharply, then falls as velocity increases. However, the exact shape and magnitude of the curve is not consistent between the materials. The difference between the luminous efficiencies for iron and aluminum, particularly at high velocities, indicates that it is not sufficient to use the same luminous efficiency for all compositions and velocities. Plain Language Summary: Material left behind by meteoroids and interplanetary dust particles entering Earth's atmosphere are important drivers of atmospheric phenomena and chemistry. There is large spread in estimates of the total meteoric mass input, in part due to uncertainty in several key parameters that are required to make mass estimates of individual particles. This work presents an experimental campaign to characterize one such parameter, the luminous efficiency, in a laboratory setting. The luminous efficiency describes the amount of a meteoroid's kinetic energy that is converted into light energy; large uncertainty in historical measurements of the luminous efficiency directly correspond to large uncertainties in mass estimates made from optical observations. The results show that there is significant variation in the luminous efficiency as a function of both particle velocity and composition, indicating that relying on a single value for the luminous efficiency is not sufficient in all cases. Key Points: Improved laboratory ablation experiments characterize luminous efficiencies of iron and aluminum at velocities greater than 10 km/sEmpirical curve fits are derived to relate the luminous efficiency and particle velocity for both speciesDifferences in iron and aluminum results indicate that the luminous efficiency varies with composition [ABSTRACT FROM AUTHOR]

This paper gives a full description of development of foreign air-to-air missiles in 2021. It pre-sents the latest advancement of American AIM-9X, AIM-120, Longshot projects, innovative air-to-air missile technologies, European ASRAAM, IRIS-T, FCAAM, MICA NG, Meteor, Russian Izdeliye 300M, Israeli Python-5 and I-Derby ER, Indian Astra. In the end, the paper summarizes the new development features of air-to-air missiles.

Abstract Calculating meteoroid masses from photometric observations relies on prior knowledge of the luminous efficiency, a parameter that is not well characterized; reported values vary by several orders of magnitude. We present results from an experimental campaign to determine the luminous efficiency as a function of mass, velocity, and composition. Using a linear electrostatic dust accelerator, iron and aluminum microparticles were accelerated to v > 10 km/s and ablated, and the light production measured. The luminous efficiency of each event was calculated and functional forms fit for each species. For both materials, the luminous efficiency is lowest at low velocities, rises sharply, then falls as velocity increases. However, the exact shape and magnitude of the curve is not consistent between the materials. The difference between the luminous efficiencies for iron and aluminum, particularly at high velocities, indicates that it is not sufficient to use the same luminous efficiency for all compositions and velocities.

The mesosphere/lower thermosphere (MLT, 80–100 km) region is an important boundary between Earth's atmosphere below and space above and may act as a sensitive indicator for anthropogenic climate change. Existing observational and modeling studies have shown the middle atmosphere and the MLT is cooling and contracting because of increasing greenhouse gas emissions. However, trend analyses are highly sensitive to the time periods covered, their length, and the measurement type and methodology used. We present for the first time the linear and 11‐year solar cycle responses in the meteor ablation altitude distributions observed by 12 meteor radars at different locations. Decreasing altitudes were seen at all latitudes (linear trends varying from −10.97 to −817.95 m dec−1), and a positive correlation with solar activity was seen for most locations. The divergence of responses at high latitudes indicates an important and complex interplay between atmospheric changes and dynamics at varying time scales. Plain Language Summary: High up in our atmosphere lies the mesosphere/lower thermosphere region (80–100 km); an important transition zone between the atmosphere below and space above. Existing studies indicate that this region is changing (cooling and contracting) in response to increasing greenhouse gas emissions, quite unlike the net warming we see near the surface. However these trend studies are often highly sensitive to choice and length of time period covered, and the methodology and type of measurements used. Here we present for the first time a self‐consistent methodology applied to 12 different meteor radar station datasets located at a diverse range of latitudes. We looked at changes in the mean peak altitude of individual meteoroid detections, and found decreasing peak altitudes at all locations examined (linear trends varying from −10.97 to −817.95 m decade−1) consistent with a global cooling and contracting of the upper atmosphere. We also examined the response to the 11‐year solar cycle and found a positive correlation with solar activity (i.e., increased meteoroid peak altitudes during solar maximum, and vice versa) for low and mid‐latitude locations. However we found an anti‐correlation at high latitudes suggestive of an important and complex interplay between atmospheric changes and dynamics at varying time scales. Key Points: Use of geographically diverse meteor radar peak detection altitudes to assess long‐term and 11‐year solar cycle (SC) trends in mesopause regionThe altitude of observed peak meteor height has decreased over time at all locations, regardless of latitude and data setPositive correlation at low‐ and mid‐latitude locations with the 11‐year SC, but more complex response at high‐latitudes [ABSTRACT FROM AUTHOR]

The paper considers the problem of studying the daily distribution of the passage of meteoroids by radio observation. The advantages of the chosen method of registration over the classical optical and photographic methods of observation are considered. A voluminous series of data was obtained using a registration facility implemented on the basis of the Center for Astrophysical Research at the North Kazakhstan University named after Manash Kozybayev. Processing, analysis and systematization of the obtained data on meteor phenomena have been carried out. Based on the obtained observational data, on the basis of the Center for Astrophysical Research at the North Kazakhstan University named after Manash Kozybayev, using the Multi VirAnalyzer program, namely the Date Recorder, the daily distribution of the meteor flight frequency was calculated. Also, with the help of the Microsoft Excel software application, diagrams of the daily distribution of the meteor passage frequency were constructed. During the analysis of the obtained diagrams of the daily distribution of the meteor passage frequency, the peak and average daily values of meteor activity were determined. Based on the daily distribution, diagrams of the frequency of meteor passages were constructed for certain months during which the Perseid and Leonid meteor showers are active. A clear correlation with the results of studies of other laboratories of a similar line of research is shown. [ABSTRACT FROM AUTHOR]

Coherent scatter echoes from disintegrating meteors and from the unstable ionospheric E‐region can overlap considerably between 90 and 110 km altitudes. As the physical origin of plasma irregularities produced by meteor trails differs starkly from that of E‐region auroral irregularities, this has consequences for winds as well as electrodynamic studies, thereby introducing a need to distinguish between the two types of echoes. To that goal, we have developed a novel separation algorithm to automatically sort through arbitrarily large data sets in the region of overlap. This proves very useful when the 3D location of echoes is available. The algorithm uses a definition of crowding, or clustering, in both time and space and has been developed and tested with a comprehensive data set obtained from the recently built Canadian icebear 3D radar. We discuss the characteristics belonging to the two classes of echoes, and present statistical results about the location of each type of echo as a function of conditions. Our proposed algorithm can be applied to any coherent scatter echo data with high resolution 3D location information. Plain Language Summary: Radars measure turbulence in space plasma by bouncing a signal off of sharp plasma density gradients in the ionosphere. For decades, such coherent radars have been useful tools to investigate the ionosphere. However, when probing E‐region plasma, a coherent radar will pick up plasma produced by meteors as they enter Earth's atmosphere. We have developed an automatic algorithm to separate meteor trail echoes, as they are called, from space plasma measurements. We demonstrate the efficiency of this algorithm on the icebear 3D data set, which has an unprecedented resolution, and offers accurate 3D location data for space plasma turbulence. Key Points: Using new data from icebear 3D, we find that ionospheric turbulence overlap with meteor trail echoes between 90 and 110 km altitudeThe starkly different patterns of clustering in time and space of high latitude ionospheric turbulence and meteoric echoes are used to distinguish the echo typesThe spatial and temporal separation between observed meteor trail echoes is normally several orders of magnitude above that of ionospheric turbulence echoes at high latitudes [ABSTRACT FROM AUTHOR]

Mini-EUSO is a wide-angle fluorescence telescope that registers ultraviolet (UV) radiation in the nocturnal atmosphere of Earth from the International Space Station. Meteors are among multiple phenomena that manifest themselves not only in the visible range but also in the UV. We present two simple artificial neural networks that allow for recognizing meteor signals in the Mini-EUSO data with high accuracy in terms of a binary classification problem. We expect that similar architectures can be effectively used for signal recognition in other fluorescence telescopes, regardless of the nature of the signal. Due to their simplicity, the networks can be implemented in onboard electronics of future orbital or balloon experiments.

Abstract The mesosphere/lower thermosphere (MLT, 80–100 km) region is an important boundary between Earth's atmosphere below and space above and may act as a sensitive indicator for anthropogenic climate change. Existing observational and modeling studies have shown the middle atmosphere and the MLT is cooling and contracting because of increasing greenhouse gas emissions. However, trend analyses are highly sensitive to the time periods covered, their length, and the measurement type and methodology used. We present for the first time the linear and 11‐year solar cycle responses in the meteor ablation altitude distributions observed by 12 meteor radars at different locations. Decreasing altitudes were seen at all latitudes (linear trends varying from −10.97 to −817.95 m dec−1), and a positive correlation with solar activity was seen for most locations. The divergence of responses at high latitudes indicates an important and complex interplay between atmospheric changes and dynamics at varying time scales.

A novel computer vision‐based meteor head echo detection algorithm is developed to study meteor fluxes and their physical properties, including initial range, range coverage, and radial velocity. The proposed Algorithm for Head Echo Automatic Detection (AHEAD) comprises a feature extraction function and a Convolutional Neural Network (CNN). The former is tailored to identify meteor head echoes, and then a CNN is employed to remove false alarms. In the testing of meteor data collected with the Jicamarca 50 MHz incoherent scatter radar, the new algorithm detects over 180 meteors per minute at dawn, which is 2 to 10 times more sensitive than prior manual or algorithmic approaches, with a false alarm rate less than 1 percent. The present work lays the foundation of developing a fully automatic AI‐meteor package that detects, analyzes, and distinguishes among many types of meteor echoes. Furthermore, although initially evaluated for meteor data collected with the Jicamarca VHF incoherent radar, the new algorithm is generic enough that can be applied to other facilities with minor modifications. The CNN removes up to 98 percent of false alarms according to the testing set. We also present and discuss the physical characteristics of meteors detected with AHEAD, including flux rate, initial range, line of sight velocity, Signal‐to‐Noise Ratio, and noise characteristics. Our results indicate that stronger meteor echoes are detected at a slightly lower altitude and lower radial velocity than other meteors. Key Points: A highly capable meteor head echo detection algorithm is developedIntroducing the complete automatic package of meteor detection with computer vision and deep learningMeteors with higher Signal‐to‐Noise Ratio are detected in a slightly lower range and with a lower radial velocity [ABSTRACT FROM AUTHOR]

Copyright of Larq Journal for Philosophy, Linguistics & Social Sciences is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper gives a full description of development of foreign air-to-air missiles in 2020. It presents the latest advancement of AIM-9X, AIM-120, MSDM, Gunslinger, Longshot, innovative long-range air-to-air missile, IRIS-T, MICA, Meteor, Russian air-to-air missile, Astra BVRAAM. In the end, the paper summarizes the new development features of air-to-air missiles.

Meteor observations provide information about Solar System constituents and their influx onto Earth, their interaction processes in the atmosphere, as well as the neutral dynamics of the upper atmosphere. This study presents optical, radar, and infrasound measurements of a daytime fireball that occurred on 4 December 2020 at 13:30 UTC over Northeast Sweden. The fireball was recorded with two video cameras, allowing a trajectory determination to be made. The orbital parameters are compatible with the Northern Taurid meteor shower. The dynamic mass estimate based on the optical trajectory was found to be 0.6–1.7 kg, but this estimate can greatly vary from the true entry mass significantly due to the assumptions made. The meteor trail plasma was observed with an ionosonde as a sporadic E-like ionogram trace that lasted for 30 min. Infrasound emissions were detected at two sites, having propagation times consistent with a source location at an altitude of 80–90 km. Two VHF specular meteor radars observed a 6 minute long non-specular range spread trail echo as well as a faint head echo. Combined interferometric range-Doppler analysis of the meteor trail echoes at the two radars, allowed estimation of the mesospheric horizontal wind altitude profile, as well as tracking of the gradual deformation of the trail over time due to a prevailing neutral wind shear. This combined analysis indicates that the radar measurements of long-lived non-specular range-spread meteor trails produced by larger meteoroids can be used to measure the meteor radiant by observing the line traveled by the meteor. Furthermore, a multistatic meteor radar observation of these types of events can be used to estimate mesospheric neutral wind altitude profiles.

We present a machine-learning approach to detect and analyze meteor echoes (MADAME), which is a radar data processing workflow featuring advanced machine-learning techniques using both supervised and unsupervised learning. Our results demonstrate that YOLOv4, a convolutional neural network (CNN)-based one-stage object detection model, performs remarkably well in detecting and identifying meteor head and trail echoes within processed radar signals. The detector can identify more than 80 echoes per minute in the testing data obtained from the Jicamarca high power large aperture (HPLA) radar. MADAME is also capable of autonomously processing data in an interferometer mode, as well as determining the target’s radiant source and vector velocity. In the testing data, the Eta Aquarids meteor shower could be clearly identified from the meteor radiant source distribution analyzed automatically by MADAME, thereby demonstrating the proposed algorithm’s functionality. In addition, MADAME found that about 50 percent of the meteors were traveling in inclined and near-inclined circular orbits. Furthermore, meteor head echoes with a trail are more likely to originate from shower meteor sources. Our results highlight the capability of advanced machine-learning techniques in radar signal processing, providing an efficient and powerful tool to facilitate future and new meteor research.

The Late Babylonian Astronomical Diaries and related texts contain a large body of records of astronomical phenomena which were carefully and systematically observed between about 600 BC and 50 BC. Most of these observations are of regular (cyclical) astronomical phenomena such as passages of the planets past certain stars, the first and last appearances, stations, and acronychal risings of the planets, and eclipses of the sun and moon. However, a smaller number of observations of irregular, transient astronomical phenomena were also recorded. In addition to being of historical interest, records of certain transient phenomena have applications in modern science. In this paper, we provide a catalog of three types of transient phenomena observed by the Babylonians – haloes, meteors, and comets – as well as some basic analysis of the records and the necessary contextual information to facilitate their analysis and use by other scholars. [ABSTRACT FROM AUTHOR]

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We carried out a detailed study of a bright meteor detected over the Khamar-Daban mountain range on August 12, 2020 at 14:37:35 UT by two automatic video monitoring stations functioning on the territory of the Tunka Valley (Republic of Buryatia) as part of the SkyLine project. The astro- and photometric parameters of the event were determined, its belonging to a specific meteor stream was established, and the spatial parameters of the trajectory with a projection onto the terrain were recovered. The data on the main physical characteristics of the meteor particle were obtained, including the geocentric velocity and orbital parameters. The chemical composition of the meteoroid was analyzed from the spectral data of the track. The potential possibility of using meteor phenomena as a tool to study the upper layers of the atmosphere was considered. [ABSTRACT FROM AUTHOR]

Abstract Background In the phase 3 METEOR trial, cabozantinib improved progression-free survival (PFS) and overall survival (OS) versus everolimus in patients with advanced RCC after prior antiangiogenic therapy. Methods In this exploratory analysis, plasma biomarkers from baseline and week 4 from 621 of 658 randomized patients were analyzed for CA9, HGF, MET, GAS6, AXL, VEGF, VEGFR2, and IL-8. PFS and OS were analyzed by baseline biomarker levels as both dichotomized and continuous variables using univariate and multivariable methods. For on-treatment changes, PFS and OS were analyzed using fold change in biomarker levels at week 4. Biomarkers were considered prognostic if p

The Meteor and ionospheric Irregularity Observation System (MIOS), which consists of multi‐station optical subsystem at Ledong (18.4°N, 109°E) and Sanya (18.3°N, 109.6°E), and radar subsystem including a 38.9 MHz all‐sky interferometric radar and a 47.5 MHz coherent phased array radar at Ledong, has been in full operational since December 2021. This paper describes the system design and first results of meteor plasma density irregularities and corresponding meteoroids. The MIOS optical subsystem consists of a few tens of video cameras for observing optical meteor trail and spectrum. The MIOS phased array is composed of 135 Yagi antennas, arranged in sword‐like grid and grouped into 15 identical subarrays, with distances separated by 2–19.5 times the wavelength for unambiguous interferometry measurements. The phased array can form narrow and wide beams, with half power width of 8° and 24° in azimuth, respectively, allowing narrow‐beam pulse‐to‐pulse steering and wide‐beam multi‐baseline imaging observations in the east‐west direction. Observational results show that the MIOS is capable of unambiguously locating various meteor echoes, that is, head, specular and non‐specular echoes, revealing the structural evolution of field‐aligned and non‐field‐aligned irregularity, and of determining the properties of meteoroids producing/not producing irregularities. Cases of bright meteors producing non‐field‐aligned irregularities and not producing field‐aligned irregularities respectively are presented, and possible factors affecting the generation of meteor trail irregularities are discussed based on current understanding. It is expected that the MIOS will provide an important tool to study the generation and evolution of various meteor trail irregularities and the properties of the corresponding meteoroids. Plain Language Summary: Meteoroids entering the Earth's atmosphere significantly disturb the background ionosphere, producing ionized columns and plasma density irregularities, change the ionospheric composition, and even seed large‐scale ionospheric irregularity structures. However, due to the limitations of previous measurements, some physical processes, for example, how efficiently various meteoroids affect the background ionosphere, either producing or not producing some specific meteor trail irregularity phenomena, and the related meteoroid properties and origins, are less well understood. This calls for a facility to measure the properties of both the meteor trail and its corresponding meteoroid, and thus to reveal potential factors affecting the generation of meteor trail irregularities and the disturbance of the background ionosphere. Under the support of national natural science foundation of China, a Meteor and ionospheric Irregularity Observation System (MIOS) was designed to simultaneously capture the radar and optical signatures of meteors and plasma density irregularities. Here we report the initial measurements of the MIOS, which demonstrate its capabilities for observing various meteor and irregularity phenomena. Key Points: An optical and radar facility (MIOS) intended to study how meteoroids change the Earth's background ionosphere has been developedFirst observations of field‐ and non field‐aligned meteor irregularities and the corresponding meteoroids from the facility are presentedThe facility is expected to play an important role in the study of various meteors, their origin and possible processes affecting ionosphere [ABSTRACT FROM AUTHOR]

The calculation results of the evolution of meteoroid streams obtained using the model described by Shustov and Zolotarev (2022) are presented. The model was implemented using the REBOUND software package. The evolution of model meteoroid streams associated with comets 96P/Machholz and 2P/Encke was considered. It was shown that the distribution of mass spectra is formed in the meteoroid stream: the mass index at the center of the stream , while at the edge of the stream may exceed 2. There are two causes of such changes in the structure of the meteoroid stream: (1) the initial velocity of particle ejection from the comet nucleus strongly depends on the particle size, and small particles move away from the nucleus faster; (2) small particles are more exposed to the action of radiation forces and therefore scatter in space faster than large particles, so the mass index at the center of the stream decreases. These results are consistent with the results obtained by other authors from observations of meteor streams, in particular, the Arietids stream. [ABSTRACT FROM AUTHOR]

It is known from observations that the mass spectra of meteoric bodies (meteoroids) that cause the phenomena of sporadic meteors and bodies in meteor showers are close in differential form to dN ∝ M–sdM, while the mass index s ≈ 2 for sporadic meteors and s < 2 (1.5−1.8) for meteor showers. We have analyzed the causes of this difference. We assume that the value of the index s ≈ 2 implies the randomness of the meteoroid stream formation both as a result of the decay of comets and of collisions of asteroids and larger meteoroids. The deviation of the index from 2 is due to the influence of the further evolution of meteoroid streams. This study considers the formulation of the first part of the problem of the evolution of the mass spectrum of bodies in meteoroid streams. This part refers to the determination of the velocity field of particles of various masses escaping the comet nucleus, i.e., substantiation of the choice of input parameters of the corresponding numerical model for calculating the further evolution of the meteoroid stream. An important feature is the consideration of an ensemble of particles of various sizes in the range of sizes (masses) that allow the use of the most abundant radar data on determining the meteoroid masses for comparison. [ABSTRACT FROM AUTHOR]

This article discusses some basic concepts related to meteor astronomy, as well as the use of the correct terminology when working in Bulgarian. Due to the huge volume of topics, this is the second part of an upcoming series that examines only the most general principles in meteor science. The article can serve the public observatories and similar structures related to the teaching of amateur astronomy (due to the lack of such literature in Bulgarian), and meteor phenomena will continue to attract the attention of a wide range of people, giving them mostly a strong, emotional impact! [ABSTRACT FROM AUTHOR]

In studying the connections of the δ-Cancrids (DCA) meteor stream, consisting of the northern (NCC) and southern (SCC) branches, with the comet–asteroid complex, the structure of the shower was studied using visual and television observations. According to visual observations, it was found that for meteors with a minimum recorded stellar magnitude of +3m and brighter, the maximum of activity ZHR = 8.6 ± 1.8 is observed at the Sun's longitude 298.5° ± 1.2°, while the parameter r of the luminosity function during the period of the shower activity varies in the range of 1.5–2.0. For meteors weaker than +3m, the moment of maximum occurs 1.4° later than for brighter meteors. For the orbits of meteors of the NCC and SCC branches, obtained from television observations, the dependence of the values of the semimajor axes and eccentricities on the mass of meteoroids was also revealed. The orbit separation time for the δ-Cancrid meteors in the meteor magnitude range from 0m to +3m due to the nongravitational Poynting–Robertson effect is 22–26 thousand years for the southern branch SCC, and 24–29 thousand years for the northern branch NCC. [ABSTRACT FROM AUTHOR]

Using the multiband imager MapCam on board the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer) spacecraft, we identified 77 instances of proposed exogenic materials distributed globally on the surface of the B-type asteroid (101955) Bennu. We identified materials as exogenic on the basis of an absorption near 1  |$\mu$| m that is indicative of anhydrous silicates. The exogenic materials are spatially resolved by the telescopic camera PolyCam. All such materials are brighter than their surroundings, and they are expressed in a variety of morphologies: homogeneous, breccia-like, inclusion-like, and others. Inclusion-like features are the most common. Visible spectrophotometry was obtained for 46 of the 77 locations from MapCam images. Principal component analysis indicates at least two trends: (i) mixing of Bennu's average spectrum with a strong 1- |$\mu$| m band absorption, possibly from pyroxene-rich material, and (ii) mixing with a weak 1- |$\mu$| m band absorption. The end member with a strong 1- |$\mu$| m feature is consistent with Howardite-Eucrite-Diogenite (HED) meteorites, whereas the one showing a weak 1- |$\mu$| m feature may be consistent with HEDs, ordinary chondrites, or carbonaceous chondrites. The variation in the few available near-infrared reflectance spectra strongly suggests varying compositions among the exogenic materials. Thus, Bennu might record the remnants of multiple impacts with different compositions to its parent body, which could have happened in the very early history of the Solar system. Moreover, at least one of the exogenic objects is compositionally different from the exogenic materials found on the similar asteroid (162173) Ryugu, and they suggest different impact tracks. [ABSTRACT FROM AUTHOR]