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It has been generally accepted that the originators of the double star astronomy were Christian Mayer and William Herschel. We recovered the memory of the poorly known Italian astronomer Giovanni Battista Hodierna, who published the first catalogue of stellar binaries over a century before Mayer and Herschel. We analysed the fourth section of 1654 G. B. Hodierna's book ' De systemate orbis cometici deque admirandis coeli characteribus '. There, Hodierna listed a dozen pairs of stars whose identification with modern star names had been lost for centuries. To identify the pairs, we used Hodierna's Latin descriptions of location in constellations for all primary stars, ecliptic coordinates and angular separations to companions for some, and the Washington Double Star, Hipparcos , and Gaia catalogues. We were able to identify the twelve primaries and eleven multiple systems with companions, of which nine were double and two were triple. Besides, with up-to-date data, we confirmed that four systems are physically bound: Atlas and Pleione, |$\alpha ^{1,2}$| Lib, |$\nu ^{1,2}$| Dra, and |$\theta ^{1}$| Ori A, C, and D. The other seven pairs are alignments of very bright stars at different distances. [ABSTRACT FROM AUTHOR]

A temporally stable functional brain network pattern among coordinated brain regions is fundamental to stimulus selectivity and functional specificity during the critical period of brain development. Brain networks that are recruited in time to process internal states of others' bodies (like hunger and pain) versus internal mental states (like beliefs, desires, and emotions) of others' minds allow us to ask whether a quantitative characterization of the stability of these networks carries meaning during early development and constrain cognition in a specific way. Previous research provides critical insight into the early development of the theory-of-mind (ToM) network and its segregation from the Pain network throughout normal development using functional connectivity. However, a quantitative characterization of the temporal stability of ToM networks from early childhood to adulthood remains unexplored. In this work, reusing a large sample of children (n = 122, 3–12 years) and adults (n = 33) dataset that is available on the OpenfMRI database under the accession number ds000228, we addressed this question based on their fMRI data during a short and engaging naturalistic movie-watching task. The movie highlights the characters' bodily sensations (often pain) and mental states (beliefs, desires, emotions), and is a feasible experiment for young children. Our results tracked the change in temporal stability using an unsupervised characterization of ToM and Pain networks DFC patterns using Angular and Mahalanobis distances between dominant dynamic functional connectivity subspaces. Our findings reveal that both ToM and Pain networks exhibit lower temporal stability as early as 3-years and gradually stabilize by 5-years, which continues till adolescence and late adulthood (often sharing similarity with adult DFC stability patterns). Furthermore, we find that the temporal stability of ToM brain networks is associated with the performance of participants in the false belief task to access mentalization at an early age. Interestingly, higher temporal stability is associated with the pass group, and similarly, moderate and low temporal stability are associated with the inconsistent group and the fail group. Our findings open an avenue for applying the temporal stability of large-scale functional brain networks during cortical development to act as a biomarker for multiple developmental disorders concerning impairment and discontinuity in the neural basis of social cognition. [ABSTRACT FROM AUTHOR]

Precipitation records in North Patagonia (Argentina) are scarce, which hinders climate research. This research aims to assess the performance of four novel local monthly datasets together with three commonly used global datasets for North Patagonia to evaluate the advantages and disadvantages of each one. First, four different local observed-interpolated datasets were built, two using the Angular Distance Weighted (ADW) method and two using ordinary Kriging. In addition, the global datasets CRU, ERA5-Land, and GPCC were evaluated. To assess the performance of the precipitation datasets, four metrics were used to evaluate the systematic errors (bias), the mean errors, the representation of time variations, and the representation of the probability density function. The ERA5-Land with a correction factor stands out as the best global dataset and it also presents the overall best representation of the probability density function (PDF). The built dataset with ADW using a precipitation index presents the overall best performance, especially in representing the time variations. Even though ADW presents an overall better performance, ERA5-Land with a correction factor presents a better performance in terms of errors in the southern region (south of 40°S). The novel dataset is freely available through the link provided in the conclusions section. [ABSTRACT FROM AUTHOR]

In the field of coherent direction of arrival (DOA) estimation, traditional subspace-based algorithms encounter difficulties due to the loss of rank in the signal covariance matrix. To mitigate this concern, we introduce a novel technique called augmented space smoothing (ASS). The proposed method exploits the maximum eigenvectors and their corresponding eigenvalues of the signal subspace, which benefits the utilize both auto-correlation and inter-correlation information. By assigning distinct weights to the auto-correlation and cross-correlation information, our method enables accurate direction-finding estimation of two fully coherent signals located at varying angular intervals. Furthermore, we provide a rigorous proof that the proposed ASS matrix efficiently recovers the matrix rank matching the source quantity. By utilizing these fundamental properties, our approach demonstrates a de-coherence ability to address the rank deficiency issue in traditional subspace-based algorithms used for coherent signal processing tasks. Compared to existing spatial smoothing methods, such as spatial smoothing pre-processing (SSP), modified spatial smoothing pre-processing (MSSP), subarrays cross-correlation (SCC), improved spatial smoothing (ISS), enhanced spatial smoothing (ESS) and enhanced spatial smoothing pre-processing based on signal space (ESS-SS), our proposed algorithm demonstrates a superior estimation performance. Finally, we have verified the effectiveness of our algorithm through the simulation results of signal-to-noise ratio (SNR), the number of snapshots, and angular separation. [ABSTRACT FROM AUTHOR]

This paper proposes an all-sky star map identification algorithm that can simultaneously achieve high identification probability, low algorithm complexity, and small databases for well photometric and intrinsic parameters-calibrated star sensors. The proposed algorithm includes three main steps. First, a binary radial pattern table is constructed offline. Then, the maximum value matching of the radial pattern is performed between the star spots and the guide stars, and the star pairs (i.e., the minimum star map) after radial pattern matching undergo a coarse matching through angular distance cross-validation. Finally, a reference star map is designed based on the identified star pairs, and the matching of all the star spots in the field of view is realized. Simulation and analysis results show that the database required by the proposed algorithm for 5,000 guide stars is not larger than 200 KB. Also, when false and missing star spots account for 50% of all guide stars and the star spot extraction error is 0.5 pixel (the corresponding pointing error is 26″), the average star map identification time of the proposed algorithm is less than 2 ms, and its identification probability is higher than 98%. The results demonstrate that the proposed algorithm performs better than similar algorithms. [ABSTRACT FROM AUTHOR]

Mollusk shells protect the animals that form and inhabit them. They are composites of minerals and organics, with diverse mesostructures, including nacre, prismatic calcite, crossed‐lamellar aragonite, and foliated calcite. Twins, that is, crystals mirror symmetric with respect to their coherent interface, occurring as formation or deformation twins, are observed in all mollusk shell mesostructures but never within calcite prisms. Here, nanotwins and microwins within single calcite prisms are observed in different shells. Using Polarization‐dependent Imaging Contrast (PIC) mapping with 20–60 nm resolution, twins are observed to be 0.2–3 µm thick layers of differently oriented and colored crystals with respect to the main prism crystal. Multiple twins are interspersed with the prism crystal, parallel to one another, and similarly oriented. When comparing images of calcite prisms and twins obtained by PIC mapping and by Electron Back‐Scattered Diffraction (EBSD), the images correspond precisely. All twins are e‐twin types, with 127° angular distance between c‐axes. E‐twins are the most common deformation twins in geologic calcite, as also observed here in Carrara marble. Location of all twins near the outer surface of all shells and e‐twin type both suggest that twins within calcite prisms in mollusk shells result from deformation twinning. [ABSTRACT FROM AUTHOR]

To verify the advantages of Virtual Fixtures (VFs) by comparing the result of guide plate navigation (GPN) and VFs in robot-assisted osteotomy. Robot-assisted surgery has been extensively applied in traditional orthopedic surgeries. It fundamentally improves surgeries' cutting accuracy. In addition, many key techniques have been applied in bone cutting to increase the procedure's safety in various ways. In this paper, two robot-assisted osteotomy methods are proposed. Three operators with no osteotomy experience performed plane cutting with the assistance of a robot. GPN and VFs were applied to assist the Sawbones cutting. Each operator has five attempts using each method to perform bone cutting, distance errors and angular errors were recorded. The advantage of Sawbones is that there is no influence from soft tissues and blood. It can give a more precise measurement. The results show that both methods have high accuracy with the robot's assistance. VFs have higher accuracy in comparison with GPN. With GPN, the mean distance and angular error of the three operators were 2.974 ± 0.282 mm and 4.737 ± 0.254°. With VFs, the mean range and angular error of the three operators were 1.857 ± 0.349 mm and 2.24 ± 0.123°, respectively. VFs limited the robot's end in the planned area, increasing the accuracy and safety of robot-assisted osteotomy. [ABSTRACT FROM AUTHOR]

The optimal scan pattern for full-arch digital implant impressions remains to be determined. This study aimed to analyze the effects of different scan patterns on the trueness of intraoral scanners for full-arch digital implant impressions. A maxillary plaster model with 4 implant analogs was employed as the master model. Scan bodies were attached to the master model and scanned with a laboratory scanner to obtain reference data. Test scans were obtained using 3 different scan patterns with Cerec Primescan and Trios 3. Each test datum was superimposed onto the reference data. The trueness was assessed by determining the 3D distance and angular deviations between the test and reference data. Significant differences in 3D distance deviation were detected among the scan patterns for both scanners. Significant differences in angle deviation were detected among the scan patterns for the Cerec Primescan, whereas it was not substantial for the Trios 3. Cerec Primescan exhibited superior trueness across all scan patterns compared with Trios 3. The zigzag pattern resulted in more accurate scans for the Cerec Primescan, whereas both the zigzag and occlusal-palatal-buccal patterns showed higher accuracy for the Trios 3. [ABSTRACT FROM AUTHOR]

The creation of a dark hole (DH) region in the science image for exoplanet direct detection depends on deformable mirrors (DMs), where the imperfect control of DM limits the achievable contrast. The mirror surface height resolution is set by the DM drive electronics, and the quantization errors in DM impact the contrast in the DH. Consequently, determining the optimal voltage value for the flattening map of DM is essential, as it involves balancing dynamic and accuracy considerations. We conduct a numerical study to examine the impact of these parameters on microelectromechanical DM within the high-contrast field of view of several DHs with various characteristics and optical configurations. Our analysis includes an exploration of their influence on both small and moderate angular separations. We compare our numerical results with a formula available in the literature that aims to capture the dependence of contrast on DM quantization errors. We show that the formula accuracy to predict the contrast limit when the DM deflection curves follow the as-manufactured quadratic power law is dependent on the DM flattening map voltage domain, regardless of DH size and angular separations. Further these results appear to be insensitive to factors such as actuator number, coronagraph type, set-up architecture, and science objective (small or moderate angular separations). We provide guidelines for determining the optimal voltage for the DM flattening map, discuss the domain validity of the formula used to predict DM quantization errors on the contrast, and provide insights into balancing DM actuator density and mirror surface height resolution. [ABSTRACT FROM AUTHOR]

The mass distribution in the Local Group (LG), dominated by the Andromeda (M31) and Milky Way (MW) pair, is highly anisotropic. We use the APOSTLE simulations to examine how this anisotropy manifests on the spatial distribution and kinematics of dwarf galaxies out to a distance of |$d_{\rm MW}\sim 3$|  Mpc from the MW. The simulations indicate a preference for dwarfs to be located near the axis defined by the MW-M31 direction, even for dwarfs in the LG periphery (LGP; i.e. at distances |$1.25\ \lt\ d_{\rm MW}/$| Mpc |$\lt\ 3$|⁠). The 'Hubble flow' in the periphery is also affected; at fixed |$d_{\rm MW}$| the mean recession speed, |$\langle V_{\rm rad} \rangle$|⁠ , varies with angular distance to M31, peaking in the anti-M31 direction and reaching a minimum behind M31. The M31-MW mass decelerates the local expansion; the LG 'turnaround radius' (i.e. where |$\langle V_{\rm rad} \rangle =0$|⁠) in APOSTLE is at |$r \sim 1.25$|  Mpc from the LG barycentre and the pure Hubble flow (where |$\langle V_{\rm rad} \rangle \sim H_0*d$|⁠) is reached beyond |$r\sim 3$|  Mpc. The predicted flow is very cold, with a barycentric dispersion of |$\lt 40$|  km s−1. Comparing these predictions with observations yields mixed results. There is little evidence for a preferred alignment of dwarfs along the MW-M31 direction, but some evidence for an angular anisotropy in |$\langle V_{\rm rad} \rangle$|⁠. Although the 'coldness' of the Hubble flow is consistent with the simulations, it is less decelerated: relative to the MW all galaxies beyond |$d_{\rm MW} \sim 1.25$|  Mpc seem to be already on a pure Hubble flow. We argue that these oddities may result at least partly from incompleteness and inhomogeneous sky coverage in our current inventory of nearby dwarfs. [ABSTRACT FROM AUTHOR]

Abstract A temporally stable functional brain network pattern among coordinated brain regions is fundamental to stimulus selectivity and functional specificity during the critical period of brain development. Brain networks that are recruited in time to process internal states of others’ bodies (like hunger and pain) versus internal mental states (like beliefs, desires, and emotions) of others’ minds allow us to ask whether a quantitative characterization of the stability of these networks carries meaning during early development and constrain cognition in a specific way. Previous research provides critical insight into the early development of the theory-of-mind (ToM) network and its segregation from the Pain network throughout normal development using functional connectivity. However, a quantitative characterization of the temporal stability of ToM networks from early childhood to adulthood remains unexplored. In this work, reusing a large sample of children (n = 122, 3–12 years) and adults (n = 33) dataset that is available on the OpenfMRI database under the accession number ds000228, we addressed this question based on their fMRI data during a short and engaging naturalistic movie-watching task. The movie highlights the characters’ bodily sensations (often pain) and mental states (beliefs, desires, emotions), and is a feasible experiment for young children. Our results tracked the change in temporal stability using an unsupervised characterization of ToM and Pain networks DFC patterns using Angular and Mahalanobis distances between dominant dynamic functional connectivity subspaces. Our findings reveal that both ToM and Pain networks exhibit lower temporal stability as early as 3-years and gradually stabilize by 5-years, which continues till adolescence and late adulthood (often sharing similarity with adult DFC stability patterns). Furthermore, we find that the temporal stability of ToM brain networks is associated with the performance of participants in the false belief task to access mentalization at an early age. Interestingly, higher temporal stability is associated with the pass group, and similarly, moderate and low temporal stability are associated with the inconsistent group and the fail group. Our findings open an avenue for applying the temporal stability of large-scale functional brain networks during cortical development to act as a biomarker for multiple developmental disorders concerning impairment and discontinuity in the neural basis of social cognition.

Purpose: The aim of this study was to develop a model‐based deep learning architecture to accurately reconstruct fiber orientation distributions (FODs) from a reduced number of diffusion‐weighted images (DWIs), facilitating accurate analysis with reduced acquisition times. Methods: Our proposed architecture, Spherical Deconvolution Network (SDNet), performed FOD reconstruction by mapping 30 DWIs to fully sampled FODs, which have been fit to 288 DWIs. SDNet included DWI‐consistency blocks within the network architecture, and a fixel‐classification penalty within the loss function. SDNet was trained on a subset of the Human Connectome Project, and its performance compared with FOD‐Net, and multishell multitissue constrained spherical deconvolution. Results: SDNet achieved the strongest results with respect to angular correlation coefficient and sum of squared errors. When the impact of the fixel‐classification penalty was increased, we observed an improvement in performance metrics reliant on segmenting the FODs into the correct number of fixels. Conclusion: Inclusion of DWI‐consistency blocks improved reconstruction performance, and the fixel‐classification penalty term offered increased control over the angular separation of fixels in the reconstructed FODs. [ABSTRACT FROM AUTHOR]

Purpose: To determine the effect of scanning protocol, number of implants, and implant splinting on the accuracy of digital scanning in the edentulous arch. Materials and Methods: A resin-based model of an edentulous mandible with six implants was scanned with a coordinate measurement machine as a reference and then with two intraoral scanner (IOS) systems (Trios 3 and Primescan). Ten scans were taken per IOS for three experiments, and each scan was compared to the reference data to evaluate trueness and precision. Analysis involved measurement of linear and angular discrepanices using engineering software. In experiment 1, three scanning protocols were compared (curvilinear, zigzag, and half-arch). In experiment 2, three clinical situations were simulated (6 implants, 4 implants-short arch, and 4 implants-long arch). In experiment 3, the effect of implant splinting with a suture thread was measured. Normal distribution of data was examined with Shapiro-Wilk test. Levene test was used for equality of variance (a = .05). Statistical differences in distance and angular deviations were analyzed using Student t test or ANOVA with post hoc Tukey test (a = .05). Results: The best results in terms of trueness and precision were obtained with a linear scanning protocol and six implants. The results were as follows: Trios 3: trueness = 52 µm/0.42 degrees, precision = 40 µm/0.26 degrees; Primescan: trueness = 24 µm/0.28 degrees, precision = 18 µm/0.27 degrees. The scanning protocol did not significantly affect distance or angular deviation accuracy. Trueness and precision significantly decreased with four implants using Primescan and TRIOS 3. Splinting implants negatively affected accuracy with both IOS devices. Conclusion: Both IOS devices achieved clinically satisfying accuracy for distance (< 100 µm) and angular (< 0.5 degrees) deviations with six implants and a linear scanning protocol. With four implants, angular deviations sometimes differed between implants within the same group depending on the IOS and the clinical situation. [ABSTRACT FROM AUTHOR]

We studied eight new doubly eclipsing stellar systems. We found that they are all rare examples of quadruple systems of 2 + 2 architecture, where both inner pairs are eclipsing binaries. Until now, such a configuration had only been proven for dozens of systems on the whole sky. We enlarged this rare group of systems with four stars in the Small Magellanic Cloud (SMC) galaxy and four brighter stars on the northern sky. These analysed systems are the following: OGLE SMC-ECL-2339 (both eclipsing periods of 0.72884 days and 3.39576 days; mutual orbital period of 5.95 years); OGLE SMC-ECL-3075 (1.35890 d, 2.41587 d, 9.75 yr); OGLE SMC-ECL-4756 (0.91773 d, 2.06047 d, 4.34 yr); OGLE SMC-ECL-6093 (0.90193 d, 2.03033 d, 31.2 yr); GSC 01949-01700 (0.24058 d, 0.75834 d, 21.7 yr); ZTF J171602.61+273606.5 (0.36001 d, 4.51545 d, 19.5 yr); WISE J210935.8+390501 (0.33228 d, 3.51575 d, 1.9 yr); and V597 And (0.46770 d, 0.35250, 20.4 yr). These systems constitute a rare selection of W UMa stars among the doubly eclipsing quadruples. For all of the systems, new dedicated observations were obtained as well. V597 And is definitely the most interesting system for several reasons: (1) the system is the brightest in our sample; (2) it is a rare quintuple (2 + 2) + 1 system; and (3) it is also closest to the Sun. It yielded the predicted angular separation of the two components of 57 mas, which is probably within the detection limits for modern, high-angular-resolution techniques. [ABSTRACT FROM AUTHOR]

In large-scale satellite constellations, the efficiency of inter-satellite communication is paramount. Traditional topology control strategies, such as the Manhattan configuration, provide stable links but can result in indirect communication paths, affecting the efficiency of information transfer. This paper addresses this issue by proposing an innovative "3 + 1" dynamic topology control scheme. The scheme retains three static links determined by the relative angular velocity and acceleration while introducing a dynamic link based on distance and angular velocity constraints to optimize the link duration and overall network communication efficiency. To address the complexity of matching dynamic links, this paper introduces an elite strategy-based maximum weighted matching algorithm for general graphs. Compared to traditional greedy algorithms, our proposed algorithm significantly improves the link duration and topological stability. Through simulation experiments comparing communication delays between Xiamen and Los Angeles, our results show that the proposed dynamic link scheme substantially reduces the average delay, enhancing the efficiency and flexibility of inter-satellite communication. This research not only extends the duration of inter-satellite links but also provides new perspectives and methodologies for further studies on inter-satellite topology control strategies. [ABSTRACT FROM AUTHOR]

We present the serendipitous discovery of (1) a large double radio relic associated with the galaxy cluster PSZ2 G277.93 + 12.34 and (2) a new odd radio circle, ORC J1027–4422, both found in the same deep MeerKAT 1.3 GHz wide-band radio continuum image. The angular separation of the two arc-shaped cluster relics is ∼16 arcmin or ∼2.6 Mpc for a cluster redshift of z ≈ 0.158. The thin southern relic, which shows several ridges/shocks including one possibly moving inwards, has a linear extent of ∼1.64 Mpc. In contrast, the northern relic is about twice as wide, twice as bright, but only has a largest linear size of ∼0.66 Mpc. Complementary SRG/eROSITA X-ray images reveal extended emission from hot intracluster gas between the two relics and around the narrow-angle tail (NAT) radio galaxy PMN J1033–4335 (z ≈ 0.153) located just east of the northern relic. The radio morphologies of the NAT galaxy and the northern relic, which are also detected with the Australian Square Kilometer Array Pathfinder (ASKAP) at 888 MHz, suggest both are moving in the same outward direction. The discovery of ORC J1027–4422 in a different part of the same MeerKAT image makes it the fourth known single ORC. It has a diameter of ∼90 arcsec corresponding to 400 kpc at a tentative redshift of z ≈ 0.3 and remains undetected in X-ray emission. Supported by simulations, we discuss similarities between outward moving galaxy and cluster merger shocks as the formation mechanisms for ORCs and radio relics, respectively. [ABSTRACT FROM AUTHOR]

Direct scanning of silicone impressions is a valid technique. However, studies in implant-supported rehabilitations are lacking. This in vitro study aims to compare the trueness of impressions obtained with two types of silicone and their corresponding stone casts, using two laboratory scanners in a full-arch implant rehabilitation. A master cast with six dental implants was scanned with a 12-megapixel scanner to obtain a digital master cast. Ten implant impressions were made using two silicones (Zhermack and Coltene) with the open-tray technique. The impressions and stone casts were scanned by two extraoral scanners (Identica T500, Medit; and S600 ARTI, Zirkonzhan). Trueness was assessed by comparing linear and angular distances in digital casts with the master cast. A p < 0.05 significance level was considered. The results showed that for the linear measurements, 72% were higher than the master cast measurements, and no consistent pattern was observed in the angular measurements. The greatest deviations were detected between the most posterior implants, with mean values ranging between 173 and 314 µm. No significant differences were found between scanners. However, differences were observed in the distances between silicones (46.7%) and between impressions and stone casts (73.3%). This work demonstrates that the direct scanning of silicone impressions yields results comparable to those obtained from scanning gypsum casts in full-arch implant-supported rehabilitation. [ABSTRACT FROM AUTHOR]

In the covariant averaging scheme of macroscopic gravity, the process of averaging breaks the metricity of geometry. We reinterpret the back-reaction within macroscopic gravity in terms of the non-metricity of averaged geometry. This interpretation extends the effect of back-reaction beyond mere dynamics to the kinematics of geodesic bundles. With a 1 + 3 decomposition of the spacetime, we analyse how geometric flows are modified by deriving the Raychaudhuri and Sachs equations. We also present the modified forms of Gauss and Codazzi equations. Finally, we derive an expression for the angular diameter distance in the Friedmann Lemaître Robertson Walker universe and show that non-metricity modifies it only through the Hubble parameter. Thus, we caution against overestimating the influence of back-reaction on the distances. [ABSTRACT FROM AUTHOR]

Path integration is a powerful navigational mechanism whereby individuals continuously update their distance and angular vector of movement to calculate their position in relation to their departure location, allowing them to return along the most direct route even across unfamiliar terrain. While path integration has been investigated in several terrestrial animals, it has never been demonstrated in aquatic vertebrates, where movement occurs through volumetric space and sensory cues available for navigation are likely to differ substantially from those in terrestrial environments. By performing displacement experiments with Lamprologus ocellatus, we show evidence consistent with fish using path integration to navigate alongside other mechanisms (allothetic place cues and route recapitulation). These results indicate that the use of path integration is likely to be deeply rooted within the vertebrate phylogeny irrespective of the environment, and suggests that fish may possess a spatial encoding system that parallels that of mammals. By performing displacement experiments with Lamprologus ocellatus, we show evidence consistent with fish using path integration to navigate alongside other mechanisms: allothetic place cues and route recapitulation. [ABSTRACT FROM AUTHOR]

We use a galaxy sample derived from the Dark Energy Camera Legacy Survey Data Release 9 to measure the baryonic acoustic oscillations (BAO). The magnitude-limited sample consists of 10.6 million galaxies in an area of 4974 deg2 over the redshift range of [0.6, 1]. A key novelty of this work is that the true redshift distribution of the photo- z sample is derived from the self-calibration method, which determines the true redshift distribution using the clustering information of the photometric data alone. Through the angular correlation function in four tomographic bins, we constrain the BAO scale dilation parameter α to be 1.025 ± 0.033, consistent with the fiducial Planck cosmology. Alternatively, the ratio between the comoving angular diameter distance and the sound horizon, D M/ r s, is constrained to be 18.94 ± 0.61 at the effective redshift of 0.749. We corroborate our results with the true redshift distribution obtained from a weighted spectroscopic sample, finding very good agreement. We have conducted a series of tests to demonstrate the robustness of the measurement. Our work demonstrates that the self-calibration method can effectively constrain the true redshift distribution in cosmological applications, especially in the context of photometric BAO measurement. [ABSTRACT FROM AUTHOR]

Stromboli is a volcanic island in a persistent state of activity, located off the northern coast of Sicily. The paroxysms have been the most powerful explosive phenomena at Stromboli in the last 150 years. These explosions can produce ballistic projectiles that can heavily affect trails and observation sites as well as hit inhabited areas at lower elevations, down to the coast. On July 3, 2019, a paroxysm significantly affected a great portion of the island with ballistic projectiles. In particular, many decimeter and meter-sized spatter bombs hit the W flank of Stromboli, and ignited multiple fires. In May 2022, we conducted an Unmanned Aerial System photogrammetric campaign over a sector of the W flank of Stromboli that was heavily affected by the paroxysm. The largest clasts were still preserved after 3 years, not disturbed by significant mass wasting phenomena or human interference, and they were not yet hidden by the post-fire regrowth of the brush vegetation. In this study, we constrained the main sources of uncertainty affecting the bombs distribution on the ground, by characterizing a percentage of uncertain clasts, testing various density estimators, and by modeling an areal buffer around the mapped clasts. We produced a 0.18 km2 wide 1.6-cm resolution orthomosaic, a 10-cm resolution Digital Surface Model, and 2813 outlines of the mapped ballistics. Spatial distribution of the ground cover and associated uncertainty were analyzed as a function of the distance and of the angular direction from the source. [ABSTRACT FROM AUTHOR]

Context. Strongly lensed quasars are fundamental sources for cosmology. The Gaia space mission covers the entire sky with the unprecedented resolution of 0.18″ in the optical, making it an ideal instrument to search for gravitational lenses down to the limiting magnitude of 21. Nevertheless, the previous Gaia Data Releases are known to be incomplete for small angular separations such as those expected for most lenses. Aims. We present the Data Processing and Analysis Consortium GravLens pipeline, which was built to analyse all Gaia detections around quasars and to cluster them into sources, thus producing a catalogue of secondary sources around each quasar. We analysed the resulting catalogue to produce scores that indicate source configurations that are compatible with strongly lensed quasars. Methods. GravLens uses the DBSCAN unsupervised clustering algorithm to detect sources around quasars. The resulting catalogue of multiplets is then analysed with several methods to identify potential gravitational lenses. We developed and applied an outlier scoring method, a comparison between the average BP and RP spectra of the components, and we also used an extremely randomised tree algorithm. These methods produce scores to identify the most probable configurations and to establish a list of lens candidates. Results. We analysed the environment of 3 760 032 quasars. A total of 4 760 920 sources, including the quasars, were found within 6″ of the quasar positions. This list is given in the Gaia archive. In 87% of cases, the quasar remains a single source, and in 501 385 cases neighbouring sources were detected. We propose a list of 381 lensed candidates, of which we identified 49 as the most promising ones. Beyond these candidates, the associate tables in this Focused Product Release allow the entire community to explore the unique Gaia data for strong lensing studies further. [ABSTRACT FROM AUTHOR]

The angular distance of the solar flares to the projective point of the center of the solar disk on the solar spherical surface has been studied by the heliographical or helioprojective coordinates, during the periods 1975–2021 for GOES events and 2002–2021 for RHESSI events, hereafter “distance.” It gives a specific distribution curvature. It has also been noted that when using the number of solar flare events in each satellite, GOES or RHESSI, or even using the sum of the flux (class) or importance parameter, it obtains the same result, which is that the shape of the distribution curve remains in its shape without any significant change. In addition, it has been shown that the distribution curve contains a specific number of peaks. These peaks have a specific distance from the center of the solar disk that is very similar to the projection of the solar interior layers on the solar disk. For this reason, the names of these four main peaks have been given as follows: (1) the core circle (0–15°): it is a projection of the solar core onto the solar disk, (2) radiative ring (15–45°), and (3) the convection ring (45–55°). The limb ring is 80–90°. This result makes us wonder why the number of events in the middle of the solar disk is few, and also small at the solar limb, while many in the other parts in the solar disk. This suggests that we need to understand the sun better than before, and it also suggests that solar flares are connected to each other through the solar interior layers, the extent of which may reach the convection zone or perhaps beyond that, or the opacity of the convection zone may be less than the currently estimated value. [ABSTRACT FROM AUTHOR]

Abnormal-trajectory detection can be used to detect fraudulent behavior of taxi drivers transporting passengers. Aiming at the problem that existing methods do not fully consider abnormal fragments of trajectories, this paper proposes an abnormal-trajectory detection method based on sub-trajectory classification and outlier-factor acquisition, which effectively detects abnormal sub-trajectories and further detects abnormal trajectories. First, each trajectory is reconstructed using the turning angles and is divided into multiple sub-trajectories according to the turning angle threshold and trajectory point original acceleration. The sub-trajectories are then classified according to the extracted directional features. Finally, the multivariate distances between angular adjacent segments are calculated to obtain the outlier factor, and abnormal sub-trajectories are detected. The sum of the lengths of the abnormal sub-trajectories is used to calculate the outlier score and identify abnormal trajectories. Based on experimental results using real trajectory datasets, it has been found that the proposed method performs better at detecting abnormal trajectories than other similar methods. [ABSTRACT FROM AUTHOR]

We generalize the Bourbaki, Dunkl–Williams, Hudzick–Landes, and Maligranda inequalities in normed linear spaces for various p-angular distances. Then we obtain several equality conditions of these generalized inequalities, mainly, in strictly convex spaces. In addition, corresponding to some p-angular distance, we compare the achieved upper bounds with each other. Furthermore, we present several examples and counterexamples illustrate our results. [ABSTRACT FROM AUTHOR]

The direct detection of gravitational waves by ground-based optical interferometers has opened a new window in astronomy. Besides, the sensitivity of these linear detectors to the direction of arrival of an incoming gravitational wave is limited compared to current prospects of high-precision, space-based, astrometry. Indeed, advanced methods of differential relativistic astrometry offer a unique opportunity to overcome that situation. Here, we present a novel concept for a gravitational wave antenna that uses angles between close pairs of point-like sources as natural (angular) "arms" to characterise the very tiny variations in angular separations induced by a passing gravitational wave. The proposed new astrometric gravitational wave observable proves to be a powerful tool to substantially enhance the effect of gravitational waves of different strengths by exploiting optical resolution to the fullest. Then, by optically multiplexing three (or more) of such astrometric "arms", it would be also possible to pinpoint source directions to unprecedented levels. [ABSTRACT FROM AUTHOR]

We present a tomographic analysis of metal absorption lines arising from the circumgalactic medium (CGM) of galaxies at z ≈ 0.5–2, using Multi Unit Spectroscopic Explorer (MUSE) observations of two background quasars at z ≈ 2.2 and 2.8, which are two of the few currently known quasars with multiple images due to strong gravitational lensing by galaxy clusters at z ≈ 0.6 and 0.5, respectively. The angular separations between different pairs of quasar multiple images enable us to probe the absorption over transverse physical separations of ≈0.4–150 kpc, which are based on strong lensing models exploiting MUSE observations. The fractional difference in rest-frame equivalent width (Δ W r) of Mg  ii , Fe  ii , and C  iv absorption increases on average with physical separation, indicating that the metal-enriched gaseous structures become less coherent with distance, with a likely coherence length-scale of ≈10 kpc. However, Δ W r for all the ions vary considerably over ≈0.08–0.9, indicating a clumpy CGM over the full range of length-scales probed. At the same time, paired Mg  ii absorption is detected across ≈100–150 kpc at similar line-of-sight velocities, which could be probing cool gas clouds within the same halo. No significant dependence of Δ W r is found on the equivalent width and redshift of the absorbing gas and on the galaxy environment associated with the absorption. The high-ionization gas phase traced by C  iv shows a higher degree of coherence than the low-ionization gas phase traced by Mg  ii , with ≈90 per cent of C  iv systems exhibiting Δ W r ≤ 0.5 at separations ≤10 kpc compared to ≈50 per cent of Mg  ii systems. [ABSTRACT FROM AUTHOR]

Based on the radar equation and system noise characteristics, the maximum detection range model of a space debris laser ranging system at a 1064 nm wavelength is established, taking into account the factors of atmospheric transmission and sky background radiance. Through theoretical analysis and simulation experiments, the influencing factors of atmospheric transmission and sky background radiance are studied, and the influencing factors are normalized into the maximum detection range model by polynomial fitting. The results indicate that a high atmospheric transmission comes from a high altitude and low target zenith angle; a low sky background radiance comes from a small target zenith angle and low solar altitude angle, while the angular distance has no obvious influence on the sky background radiance. The experimental results indicate that the comprehensive accuracy of the maximum detection range model of the system is 86%, and the effectiveness of the model is verified by using a 1064 nm wavelength laser ranging for the debris target with a distance of 700–1100 km and a cross section area of 4–10 m2. The model can be used to evaluate the ability of the space debris laser ranging system at a 1064 nm wavelength. [ABSTRACT FROM AUTHOR]

As Internet of Things devices become widely used in the real-world, it is crucial to protect them from malicious intrusions. However, the data scarcity of IoT limits the applicability of traditional intrusion detection methods, which are highly data-dependent. To address this, in this article, we propose the Open-Set Dandelion Network (OSDN) based on unsupervised heterogeneous domain adaptation in an open-set manner. The OSDN model performs intrusion knowledge transfer from the knowledge-rich source network intrusion domain to facilitate more accurate intrusion detection for the data-scarce target IoT intrusion domain. Under the open-set setting, it can also detect newly-emerged target domain intrusions that are not observed in the source domain. To achieve this, the OSDN model forms the source domain into a dandelion-like feature space in which each intrusion category is compactly grouped and different intrusion categories are separated, i.e., simultaneously emphasising inter-category separability and intra-category compactness. The dandelion-based target membership mechanism then forms the target dandelion. Then, the dandelion angular separation mechanism achieves better inter-category separability, and the dandelion embedding alignment mechanism further aligns both dandelions in a finer manner. To promote intra-category compactness, the discriminating sampled dandelion mechanism is used. Assisted by the intrusion classifier trained using both known and generated unknown intrusion knowledge, a semantic dandelion correction mechanism emphasises easily-confused categories and guides better inter-category separability. Holistically, these mechanisms form the OSDN model that effectively performs intrusion knowledge transfer to benefit IoT intrusion detection. Comprehensive experiments on several intrusion datasets verify the effectiveness of the OSDN model, outperforming three state-of-the-art baseline methods by 16.9%. The contribution of each OSDN constituting component, the stability and the efficiency of the OSDN model are also verified. [ABSTRACT FROM AUTHOR]

The influence of the relative positions of a sound stimulus and a background masker on the components of evoked potentials (EPs) in the human brain in response to sound offset was studied. Sound stimuli were presented dichotically and sound image positions were specified by interaural level differences. The test signal and masker were located at a single point in space or were separated by designed angular distances of 90° or 180°. Coincidence of the positions of the signal and masker led to significant decreases in the amplitudes and increases in the latencies of the N1, P2, and N2 components of offset responses. Separation of the signal from the masker led to increases in response amplitude almost to the level of the response to the signal in silence, along with decreases in the latencies of all response components, which presumptively indicates successful extraction of the stimulus from the background. [ABSTRACT FROM AUTHOR]

Background: The adoption of four‐dimensional cone beam computed tomography (4DCBCT) for image‐guided lung cancer radiotherapy is increasing, especially for hypofractionated treatments. However, the drawbacks of 4DCBCT include long scan times (∼240 s), inconsistent image quality, higher imaging dose than necessary, and streaking artifacts. With the emergence of linear accelerators that can acquire 4DCBCT scans in a short period of time (9.2 s) there is a need to examine the impact that these very fast gantry rotations have on 4DCBCT image quality. Purpose: This study investigates the impact of gantry velocity and angular separation between x‐ray projections on image quality and its implication for fast low‐dose 4DCBCT with emerging systems, such as the Varian Halcyon that provide fast gantry rotation and imaging. Large and uneven angular separation between x‐ray projections is known to reduce 4DCBCT image quality through increased streaking artifacts. However, it is not known when angular separation starts degrading image quality. The study assesses the impact of constant and adaptive gantry velocity and determines the level when angular gaps impair image quality using state‐of‐the‐art reconstruction methods. Methods: This study considers fast low‐dose 4DCBCT acquisitions (60–80 s, 200‐projection scans). To assess the impact of adaptive gantry rotations, the angular position of x‐ray projections from adaptive 4DCBCT acquisitions from a 30‐patient clinical trial were analyzed (referred to as patient angular gaps). To assess the impact of angular gaps, variable and static angular gaps (20°, 30°, 40°) were introduced into evenly separated 200 projections (ideal angular separation). To simulate fast gantry rotations, which are on emerging linacs, constant gantry velocity acquisitions (9.2 s, 60 s, 120 s, 240 s) were simulated by sampling x‐ray projections at constant intervals using the patient breathing traces from the ADAPT clinical trial (ACTRN12618001440213). The 4D Extended Cardiac‐Torso (XCAT) digital phantom was used to simulate projections to remove patient‐specific image quality variables. Image reconstruction was performed using Feldkamp‐Davis‐Kress (FDK), McKinnon‐Bates (MKB), and Motion‐Compensated‐MKB (MCMKB) algorithms. Image quality was assessed using Structural Similarity‐Index‐Measure (SSIM), Contrast‐to‐Noise‐Ratio (CNR), Signal‐to‐Noise‐Ratio (SNR), Tissue‐Interface‐Width‐Diaphragm (TIW‐D), and Tissue‐Interface‐Width‐Tumor (TIW‐T). Results: Patient angular gaps and variable angular gap reconstructions produced similar results to ideal angular separation reconstructions, while static angular gap reconstructions produced lower image quality metrics. For MCMKB‐reconstructions, average patient angular gaps produced SSIM‐0.98, CNR‐13.6, SNR‐34.8, TIW‐D‐1.5 mm, and TIW‐T‐2.0 mm, static angular gap 40° produced SSIM‐0.92, CNR‐6.8, SNR‐6.7, TIW‐D‐5.7 mm, and TIW‐T‐5.9 mm and ideal produced SSIM‐1.00, CNR‐13.6, SNR‐34.8, TIW‐D‐1.5 mm, and TIW‐T‐2.0 mm. All constant gantry velocity reconstructions produced lower image quality metrics than ideal angular separation reconstructions regardless of the acquisition time. Motion compensated reconstruction (MCMKB) produced the highest contrast images with low streaking artifacts. Conclusion: Very fast 4DCBCT scans can be acquired provided that the entire scan range is adaptively sampled, and motion‐compensated reconstruction is performed. Importantly, the angular separation between x‐ray projections within each individual respiratory bin had minimal effect on the image quality of fast low‐dose 4DCBCT imaging. The results will assist the development of future 4DCBCT acquisition protocols that can now be achieved in very short time frames with emerging linear accelerators. [ABSTRACT FROM AUTHOR]

In chemical industries, multiphase flows in a bubble column reactor are frequently observed. The nonlinearity associated with bubble hydrodynamics, such as bubble–bubble and bubble–liquid interactions, gives rise to complex spatiotemporal patterns with increased gas or liquid velocities, which are extremely difficult to model and predict. In the current study, we propose a new, computationally efficient recurrence-based approach involving the angular separation between suitably defined state vectors and implement it on the experimental multiphase flow variables. The experimental dataset that consists of image frames obtained using a high-speed imaging system is generated by varying air and water flow rates in a bubble column reactor setup. The recurrence plots using the new approach are compared with those derived from conventional recurrence, considering standard benchmark problems. Further, using the recurrence plots and recurrence quantification from the new recurrence methodology, we discover a transition from a high recurrence state to a complex regime with very low recurrence for an increase in airflow rate. Determinism exhibits a rise for the decrease in airflow rate. A sharp decline in determinism and laminarity, signifying the quick shift to complex dynamics, is more prominent for spatial recurrence than temporal recurrence, indicating that the rise in airflow rate significantly impacts the spatial location of bubbles. We identify three regimes that appeared as distinct clusters in the determinism–laminarity plane. The bubbly regime, characterized by high values of determinism and laminarity, is separated by an intermediate regime from the slug flow regime, which has low determinism and laminarity. [ABSTRACT FROM AUTHOR]

This work presents the results of experimental laboratory tests on the apodization of circular and rectangular apertures using the Interferometric Apodization by Homothety (IAH) technique. The IAH approach involves splitting the amplitude of the instrumental PSF into two equal parts. One of the two produced PSFs undergoes homothety to change its transverse dimensions while its amplitude is properly controlled. The two PSFs are then combined to produce an apodized image. The diffraction wings of the resulting PSF are subsequently reduced by some variable reduction factor, depending on an amplitude parameter γ and a spread parameter η. This apodization approach was implemented in the laboratory using an interferometric set-up based on the Mach–Zehnder Interferometer (MZI). The experimental results exhibit a strong agreement between theory and experiment. For instance, the average experimental contrast obtained at a low angular separation of 2.4λ/ D does not exceed 5 × 10−4. This work also allowed us to study the influence on the apodizer's performance of some parameters, such as the wavelength and the density of the neutral filters. [ABSTRACT FROM AUTHOR]

We have demonstrated angular distribution separation of the extreme ultraviolet (EUV) emission and suprathermal ions with a significant energy reduction for ions produced using dual pulse irradiation of a planar gadolinium (Gd) target. The pulse separation time between the pre-pulse and the main laser heating pulse was set at 30 ns, and the pre-plasma was irradiated at a distance of 50 μm above the target. Angular distributions of the EUV emission and the suprathermal ions were almost isotropic and followed a cos 4 θ distribution, respectively. The suprathermal ions were emitted normal to the target along the pre-pulse laser axis. The most probable energy of the suprathermal ions was less than 2 keV, while their maximum charge state was Gd6+ with the pre-plasma, compared to an energy of about 10 keV with a maximum charge state Gd15+ without the pre-plasma. The results suggest that the collector mirror position may be chosen to achieve a long lifetime, by avoiding damage from fast ion collisions. [ABSTRACT FROM AUTHOR]

Observational data on dual supermassive black holes (SMBHs) are scarce, even though they should be common according to the current hierarchical formation model for galaxies. We present hereby a method to detect such dual systems, involving an already known quasar, as two luminosity peaks with angular separations smaller than one arcsecond (1″). It is based on the analysis of the spatial distribution of the Gaia data delivered in the Focused Product Release (FPR), that published for the first time detections made by Gaia at the epoch level. This approach relies on the selection of elongated spatial distributions of epoch measurements, due to two clumps of detections, checked against images coming from the PanSTARRS1 and 2MASS surveys. We have analyzed the 3.8 million of quasars flagged as single in the Gaia FPR extra-galactic table and we currently end up with only 8 dual AGN candidates, applying very conservative thresholds. G-band magnitude of each of the two luminosity peaks is provided for these candidates. The mean value of the angular separation between these two components is found to be equal to 0.3″. This demonstrates the ability of Gaia epoch data to detect previously unknown dual sources, which might be compact dual AGN. [ABSTRACT FROM AUTHOR]

We provide a measurement of the deficit in the Sunyaev–Zel'dovich Compton- y signal towards cosmic voids, by stacking a catalogue of 97 090 voids constructed with BOSS-DR12 data, on the y -maps built on data from the Atacama Cosmology Telescope (ACT) DR4 and the Planck satellite. We detect the void signal with a significance of |$7.3 \sigma$| with ACT and |$9.7\sigma$| with Planck , obtaining agreements in the associated void radial y -profiles extracted from both maps. The inner-void profile (for angular separations within the void angular radius) is reconstructed with significances of 4.7σ and 6.1σ with ACT and Planck , respectively; we model such profile using a simple model that assumes uniform gas (under)density and temperature, which enables us to place constraints on the product (−δv T e) of the void density contrast (negative) and the electron temperature. The best-fitting values from the two data sets are |$(-\delta _{\rm v}T_{\rm e})=(6.5\pm 2.3)\times 10^{5}\, \text{K}$| for ACT and |$(8.6 \pm 2.1)\times 10^{5}\, \text{K}$| for Planck [68 per cent confidence level (CL)], which are in good agreement under uncertainty. The data allow us to place lower limits on the expected void electron temperature at |$2.7\times 10^5\, \text{K}$| with ACT and |$5.1\times 10^5\, \text{K}$| with Planck (95 per cent CL); these results can transform into upper limits for the ratio between the void electron density and the cosmic mean as |$n^{\rm v}_{\rm e}/\bar{n}_{\rm e}\leqslant 0.73$| and 0.49 (95 per cent CL), respectively. Our findings prove the feasibility of using thermal Sunyaev–Zel'dovich observations to constrain the gas properties inside cosmic voids, and confirm that voids are under-pressured regions compared to their surroundings. [ABSTRACT FROM AUTHOR]

Link prediction in complex network is an important issue in network science. Recently, various structure-based similarity methods have been proposed. Most of algorithms are used to analyze the topology of the network, and to judge whether there is any connection between nodes by calculating the similarity of two nodes. However, it is necessary to get the extra attribute information of the node in advance, which is very difficult. Compared to the difficulty in obtaining the attribute information of the node itself, the topology of the network is easy to obtain, and the structure of the network is an inherent attribute of the network and is more reliable. The proposed method measures kinds of similarity between nodes based on non-trivial eigenvectors of Laplacian Matrix of the network, such as Euclidean distance, Manhattan distance and Angular distance. Then the classical machine learning algorithm can be used for classification prediction (two classification in this case), so as to achieve the purpose of link prediction. Based on this process, a spectral analysis-based link prediction algorithm is proposed, and named it LPbSA (Link Prediction based on Spectral Analysis). The experimental results on seven real-world networks demonstrated that LPbSA has better performance on Accuracy, Precision, Receiver Operating Curve(ROC), area under the ROC curve(AUC), Precision and Recall curve(PR curve) and balanced F Score(F-score curve) evaluation metrics than other ten classic methods. [ABSTRACT FROM AUTHOR]

An analysis of the parameter estimation uncertainty for the target location and velocity achievable using a single‐transmitter‐multiple‐receiver multistatic radar system is presented. A framework for establishing measures of multistatic radar parameter uncertainties by expansion of the bistatic radar parameter uncertainty measures is presented for systems containing omnidirectionally radiating nodes. The methodology uses analytical methods based on the Cramér–Rao Lower Bounds applied to scenarios in a two‐dimensional physical space with a single target exhibiting Doppler characteristics and a bistatic angle dependent radar cross‐section. A set of geometric descriptors is proposed to characterise the system, and parameter uncertainty results are reported as a function of these descriptors. The results indicate that angular separation between the transmitter and the centre of the receiver distribution is of greater importance than the quantity of receivers within the system when low uncertainty estimation capabilities are desired, though a minimum of two receivers must be available. The proportion of receivers within the system which contributed information crucial to obtaining the minimum estimation uncertainty is reported for systems containing different quantities of receivers. It was observed that, as the total number of receivers available increased, the proportion of receivers required to achieve the minimal uncertainty level reduces significantly. [ABSTRACT FROM AUTHOR]

Direct imaging is an active research topic in astronomy for the detection and the characterization of young substellar objects. The very high contrast between the host star and its companions makes the observations particularly challenging. In this context, post-processing methods combining several images recorded with the pupil tracking mode of telescope are needed. In previous works, we have presented a data-driven algorithm, PACO , capturing locally the spatial correlations of the data with a multivariate Gaussian model. PACO delivers better detection sensitivity and confidence than the standard post-processing methods of the field. However, there is room for improvement due to the approximate fidelity of the PACO statistical model to the time evolving observations. In this paper, we propose to combine the statistical model of PACO with supervised deep learning. The data are first pre-processed with the PACO framework to improve the stationarity and the contrast. A convolutional neural network (CNN) is then trained in a supervised fashion to detect the residual signature of synthetic sources. Finally, the trained network delivers a detection map. The photometry of detected sources is estimated by a second CNN. We apply the proposed approach to several data sets from the VLT/SPHERE instrument. Our results show that its detection stage performs significantly better than baseline methods (cADI and PCA), and leads to a contrast improvement up to half a magnitude compared to PACO. The characterization stage of the proposed method performs on average on par with or better than the comparative algorithms (PCA and PACO) for angular separation above 0.5 arcsec. [ABSTRACT FROM AUTHOR]

The results of measurements of background brightness in the near-infrared range (J, H, K bands), carried out in 2016–2023 at the Caucasus Mountain Observatory of Moscow State University was analyzed. It is shown that the instrumental background associated with the thermal radiation of the telescope is noticeable only in the band, and at operating temperatures its contribution mainly determines the level of the overall background in this band. The coefficients of a polynomial taking into account the contribution of instrumental and extra-atmospheric backgrounds are presented. It is shown that the brightness of the sky background does not depend on air temperature, but a weak dependence on the water vapor content is observed, close to that expected from model calculations: in the and bands, the background brightness decreases at a rate of mm, and in the band it grows at a rate of mm. The maximum amplitude of background brightness variability on short time scales ( min) has been estimated: % in the and bands and % in the band. The maximum contribution of Moon's radiation scattered in the atmosphere to the overall background level has been determined. It is shown that this contribution can be ignored at an angular distance from the Moon greater than even during a full moon. The average background surface brightness mag/arcsec2 in the J, H, and bands was calculated: , , and . [ABSTRACT FROM AUTHOR]

Strong gravitationally lensed supernovae (glSNe) are a powerful probe to obtain a measure of the expansion rate of the Universe, but they are also extremely rare. To date, only two glSNe with multiple images strongly lensed by galaxies have been found, but their short time delays make them unsuitable for cosmography. Here, we simulate a realistic catalogue of lensed supernovae and study the characteristics of the population of detectable systems for different surveys. Compared to previous studies, our simulations also account for the effect of microlensing and its impact on the glSNe yields. We show that the properties of glSNe in shallow surveys (such as the Zwicky Transient Facility) are determined by the need for large magnifications, which favours systems of four images with short time delays and low image separations. This picture is consistent with the properties of iPTF16geu and SN Zwicky, but is not representative of the population found in deeper surveys, which are limited by the volume of the Universe that is strongly lensed. For deeper surveys, such as the Legacy Survey of Space and Time (LSST), glSNe show longer time delays and greater angular separations, and the inclusion of microlensing results in 8  per cent of glSNe becoming demagnified under the detection threshold. In the 10 yr of the survey LSST should be able to find ≈180 systems, of which 70 will be suited for cosmography enabling a ≈1.2  per cent precision H 0 measurement with LSST glSNe. [ABSTRACT FROM AUTHOR]

We perform simulations of barchan swarms using the Two-Flank Agent-Based model investigating the effects of changing the angular separation between primary and secondary modes of wind, the density at which new dunes are injected, and the parameter q shift which controls the rate at which sediment is reorganised to restore symmetry in an asymmetric dune. Unlike previous agent-based models, we are able to produce longitudinally homogeneous size distributions and, for sparse swarms, steady longitudinal number density. We are able to constrain q shift by comparing the range of values for which longitudinally stability is observed with the range of values for which the width of asymmetry distributions is consistent with real-world swarms. Furthermore, we demonstrate dune size, asymmetry, dune density, spatial alignment, and collision dynamics are all strongly influenced by the angular separation of bimodal winds. [ABSTRACT FROM AUTHOR]

The increasing popularity of neuromarketing has led to the emergence of various measurement methods, such as webcam-based eye-tracking technology. Webcam-based eye-tracking technology is noteworthy not only for its use in laboratories but also for its ability to be applied to participants online in their natural environments through a link. However, the complexity of e-commerce interfaces necessitates high performance in eye-tracking methods. This complexity and the applicability of webcam-based eye-tracking technology in various environments have raised research questions about how its performance changes depending on the type and location of lighting. To answer these questions, experiments were conducted with 30 users in two different experimental environments illuminated by artificial and natural methods, with the lighting from the left, right, and front. Participants were asked to focus on targets located in specially prepared graphics for the experiment. In the heatmaps obtained in the eye-tracking tests, the distance and angular difference between the focal point and the target point were measured using the polar coordinate system. The findings indicate that measurements taken with lighting coming from the center were more efficient in both natural and artificial lighting types and measurements taken under natural lighting performed 24% better than artificial ones. Web camera-based eye-tracking technology is a promising method. However, detailed statistical analyses have demonstrated that for complex interfaces like e-commerce, the position and type of lighting are crucial parameters. [ABSTRACT FROM AUTHOR]

We present a direct imaging study of V892 Tau, a young Herbig Ae/Be star with a close-in stellar companion and circumbinary disk. Our observations consist of images acquired via Keck II/NIRC2 with nonredundant masking and the pyramid wavefront sensor at K ′ band (2.12 μ m) and L ′ band (3.78 μ m). Sensitivity to low-mass accreting companions and cool disk material is high at L ′ band, while complimentary observations at K ′ band probe hotter material with higher angular resolution. These multiwavelength, multiepoch data allow us to differentiate the secondary stellar emission from disk emission and deeply probe the structure of the circumbinary disk at small angular separations. We constrain architectural properties of the system by fitting geometric disk and companion models to the K ′ - and L ′ -band data. From these models, we constrain the astrometric and photometric properties of the stellar binary and update the orbit, placing the tightest estimates to date on the V892 Tau orbital parameters. We also constrain the geometric structure of the circumbinary disk, and resolve a circumprimary disk for the first time. [ABSTRACT FROM AUTHOR]

Source enumeration with large snapshots is feasible for a static uniform circular sonar array (UCSA). However, the dimension of the signal subspace in the array coordinate system exceeds the number of signal sources due to the rotation of the UCSA, which makes standard source enumeration ineffective. To address this issue, a spatial focusing approach for source enumeration with rotating UCSAs is presented. The approach is based on the concept of phase‐mode excitation and makes use of the UCSA heading information to achieve spatial focusing. The proposed algorithm provides reliable source enumeration with a high signal‐to‐noise ratio (SNR) when compared to the previous signal‐subspace transformation (SST) method. Simulations demonstrate that the proposed algorithm outperforms the other three methods in the conditions of a low SNR and a small angular separation. [ABSTRACT FROM AUTHOR]

The evolution of a de Sitter Universe is the basis for both the accelerated Universe and the late-stationary Universe. So, how do we differentiate between both universes? In this paper, we state that it is not possible to design an experiment using luminous or angular distances to distinguish between the two cases because they are the same during the de Sitter phase. However, this equivalence allows us prediction of the signal of a constant dark energy emission with a signal peak around 29.5 MeV, in which, according to our astrophysical test of survival probability, the radiation must be non-standard photons. Remarkably, experiments by EGRET and COMPTEL have observed an excess of gamma photons in this predicted region, coming from a possible decay process of dark energy emission, which may constitute the smoking gun of a late-stationary Universe with the continuous creation of non-standard radiation, an alternative approach to understanding the current stages of the Universe's evolution. [ABSTRACT FROM AUTHOR]

Peak electron density data derived from GOLD measurements during 2018–2022 are used to analyze the magnitudes and correlations of ionospheric diurnal variability at low latitudes. The correlation distance describes the correlations between spatial locations and is defined in this paper as the angular separation at which the correlation coefficient decreases from 1 to 0.7. Variations in correlation distance with local time, season, magnetic latitude, solar activity, and geomagnetic activity are discussed in this study. The average value of the zonal correlation distance is approximately 8.55° and 3.56° for the meridional direction at low geomagnetic latitudes (magnetic latitudes <30°). The statistical results indicate that both zonal and meridional correlation distances vary little with local time premidnight, while they show pronounced seasonal and latitudinal variations. Both zonal and meridional correlation distances increase with increasing solar activity and decrease with enhancing geomagnetic activity. The EIA strength and gradient mainly modulate the distributions of correlation distances related to magnetic latitude, season, and solar flux level. An empirical model is constructed to describe the temporal and spatial variations in the correlation distance at low latitudes. The study of correlation distances would contribute to a better understanding of ionospheric variability and improvements in data assimilation. Plain Language Summary: The correlation distance is an important parameter in determining the background covariance matrix in data assimilations, which helps to transfer information from observations to the model‐driven background. The study of correlation distances can not only promote a better understanding of ionospheric variability but also improve ionospheric forecasts. More than 1,400 days of GOLD Nmax (peak electron density) data are applied for the statistical analysis of the correlation distance. In general, the correlation distance presents pronounced seasonal and latitudinal variations, varies little with local time premidnight, increases with increasing solar activity, and decreases with enhancing geomagnetic activity. The morphology of the EIA has a direct control on the correlation distance. The EIA strength and gradient mainly modulate the distributions of correlation distances related to magnetic latitude, season, and solar flux level. An empirical model is constructed, and it can effectively describe the temporal and spatial variations in the correlation distance at low latitudes. The results of correlation distances could further improve the accuracy of data assimilation. Key Points: EIA structures directly control the variation of correlation distancesHorizontal correlation distances increase with solar activity and vary with seasonAn empirical model is constructed to describe the variation in correlation distances with LT, mlat, season, solar and geomagnetic activities [ABSTRACT FROM AUTHOR]

Underwater cultural relics are considered to be a scarce and valuable cultural resource. The significance of partially buried underwater cultural relics, which represents a distinct category of underwater cultural relics, has been largely overlooked in previous research. The Laoniu reef shipwreck No. 2, as an example of a partially buried shipwreck, was discovered through the utilization of side-scan sonar, multibeam echosounder and diver verification. In the investigation, multiangle surveys provided evidence to effectively discover this unique site. Beam-focusing technology and high-frequency side-scan sonar with proper distance and angular parameters can help to verify this site further. Given the potential significance of this particular site in relation to environmental transformations and human interventions, it is imperative to consider the insights derived from this case when reevaluating the methodology employed in underwater cultural relic surveys conducted in prospective regions. Consequently, this investigation holds the potential to unveil novel underwater cultural relic sites, thereby presenting a promising avenue for future discoveries. [ABSTRACT FROM AUTHOR]