Similar Objects Research Articles

FLEX: A fast and light-weight learned index for kNN search in high-dimensional space

The k Nearest Neighbors (kNN) search in high-dimensional space is a fundamental problem with various applications. In this paper, we try to solve this problem by using deep neural networks (DNNs). We apply DNNs to represent complex correlations between high-dimensional objects, enabling us to project similar objects into the same class, thus reducing the search cost. Based on DNNs, we propose two novel techniques to improve query efficiency while keeping accuracy. First, traditional DNNs typically demand extensive training data for achieving high accuracy. To decrease the training size, we design a multi-module DNN framework comprising several small modules. Each module learns to capture part of knowledge for the given query. The collective output of these sub-modules is then seamlessly integrated to form the final result. Second, with machine learning models, the size of candidates are unbounded. Thus, we design a linear-time data layout refinement algorithm, aiming to limit the number of candidates to a small constant. Empirically we find that our approach significantly outperforms the state-of-the-art methods in terms of both time efficiency and space efficiency while still attaining comparable or better accuracy.

What role does Skill Centre based consultancy serve in mathematics and statistics teaching communities of practice?

Mathematics and Statistics Teaching (MAST) is a staff facing service set up by the University of Bath Mathematics Resource Centre in September 2021. The service was created to collaborate with academics involved in mathematics and statistics teaching in their academic departments. In September 2023, MAST ended its pilot phase and entered a new growth phase fine-tuning existing structures and practices. During the pilot phase, MAST worked with academics consulting on enriching their programme of study and/or teaching practices. Specifically, the key principle that guides MAST is engaging in long-term sustainable collaborations with academic departments. As a means to address the key principle, we explore the potential of building communities of practice and supporting a wider network across the range of disciplines who encounter similar objectives. Facilitating a wider community of practice could be challenging, especially considering the tight schedule of the academics involved. We discuss our plans to cultivate communities of practice within departments and how we are working towards meeting our goal of establishing best practice and collecting evidence to support a wider community.

The visible and thermal light curve of the large Kuiper belt object (50000) Quaoar

Recent stellar occultations have allowed accurate instantaneous size and apparent shape determinations of the large Kuiper belt object (50000) Quaoar and the detection of two rings with spatially variable optical depths. In this paper we present new visible range light curve data of Quaoar from the Kepler/K2 mission, and thermal light curves at 100 and 160 µm obtained with Herschel/PACS. The K2 data provide a single-peaked period of 8.88 h, very close to the previously determined 8.84 h, and it favours an asymmetric double-peaked light curve with a 17.76 h period. We clearly detected a thermal light curve with relative amplitudes of ~ 10% at 100 and at 160 µm. A detailed thermophysical modelling of the system shows that the measurements can be best fit with a triaxial ellipsoid shape, a volume-equivalent diameter of 1090 km, and axis ratios of a/b = 1.19 and b/c = 1.16. This shape matches the published occultation shape, as well as visual and thermal light curve data. The radiometric size uncertainty remains relatively large (±40 km) as the ring and satellite contributions to the system-integrated flux densities are unknown. In the less likely case of negligible ring or satellite contributions, Quaoar would have a size above 1100 km and a thermal inertia ≤ 10 J m−2K−1s−1/2. A large and dark Weywot in combination with a possible ring contribution would lead to a size below 1080 km in combination with a thermal inertia ≳10 J m−2K−1s−1/2, notably higher than that of smaller Kuiper belt objects with similar albedo and colours. We find that Quaoar’s density is in the range 1.67–1.77 g cm−3, significantly lower than previous estimates. This density value closely matches the relationship observed between the size and density of the largest Kuiper belt objects.

JWST Near-infrared Spectroscopy of the Lucy Jupiter Trojan Flyby Targets: Evidence for OH Absorption, Aliphatic Organics, and CO2

We present observations obtained with the Near Infrared Spectrograph on JWST of the five Jupiter Trojans that will be visited by the Lucy spacecraft—the Patroclus–Menoetius binary, Eurybates, Orus, Leucus, and Polymele. The measured 1.7–5.3 μm reflectance spectra, which provide increased wavelength coverage, spatial resolution, and signal-to-noise ratio over previous ground-based spectroscopy, reveal several distinct absorption features. We detect a broad OH band centered at 3 μm that is most prominent on the less-red objects Eurybates, Patroclus–Menoetius, and Polymele. An additional absorption feature at 3.3–3.6 μm, indicative of aliphatic organics, is systematically deeper on the red objects Orus and Leucus. The collisional fragment Eurybates is unique in displaying an absorption band at 4.25 μm that we attribute to bound or trapped CO2. Comparisons with other solar system small bodies reveal broad similarities in the 2.7–3.6 μm bands with analogous features on Centaurs, Kuiper Belt objects (KBOs), and the active asteroid 238P. In the context of recent solar system evolution models, which posit that the Trojans initially formed in the outer solar system, the significant attenuation of the 2.7–3.6 μm absorption features on Trojans relative to KBOs may be the result of secondary thermal processing of the Trojans’ surfaces at the higher temperatures of the Jupiter region. The CO2 band manifested on the surface of Eurybates suggests that CO2 may be a major constituent in the bulk composition of Trojans, but resides in the subsurface or deeper interior and is largely obscured by refractory material that formed from the thermophysical processes that were activated during their inward migration.

Rotational Study of 5:3 and 7:4 Resonant Objects within the Main Classical Trans-Neptunian Belt

The 5:3 and 7:4 mean motion resonances of Neptune are at 42.3 and 43.7 au, respectively, and overlap with objects in the classical trans-Neptunian belt (Kuiper Belt). We report the complete/partial lightcurves of 13 and 14 trans-Neptunian objects (TNOs) in the 5:3 and 7:4 resonances, respectively. We report a most likely contact binary in the 7:4 resonance, 2013 FR28, with a periodicity of 13.97 ± 0.04 hr and a lightcurve amplitude of 0.94 ± 0.02 mag. With a V-/U-shaped lightcurve, 2013 FR28 has one of the largest well-sampled TNO amplitudes observed with ground-based observations, comparable to the well-determined contact binary 2001 QG298. 2013 FR28 has a mass ratio q ∼ 1 with a density ρ ∼ 1 g cm−3. We find several objects with large amplitudes and classify 2004 SC60, 2006 CJ69, and 2013 BN82 as likely contact binaries and 2001 QF331, 2003 YW179, and 2015 FP345 as likely elongated objects. We observe the 17:9 resonant or classical object 2003 SP317 that we classify as a likely contact binary. A lower estimate of 10%–50% and 20%–55% for the fraction of (nearly) equal-sized contact binaries is calculated in the 5:3 and 7:4 resonances, respectively. Surface colors of 2004 SC60, 2013 BN82, 2014 OL394, and 2015 FP345 have been obtained. Including these colors with ones from the literature reveals that elongated objects and contact binaries share the same ultrared surface color, except Manwë–Thorondor and 2004 SC60. Not only are the colors of the 7:4 and 5:3 TNOs similar to the cold classicals, but we demonstrate that the rotational properties of the 5:3 and 7:4 resonants are similar to those of the cold classicals, inferring a clear link between these subpopulations.

Split X-Jaw techniques of volumetric modulated arc radiotherapy in nasopharyngeal cancer: A dosimetric comparison.

The current study aims to compare the split x-jaw planning technique of volumetric modulated arc radiotherapy (VMAT) with the traditional open and limited jaw techniques of VAMT in nasopharyngeal carcinoma treatment. The multi-leaf collimators on the varian linear accelerator move on a carriage with a maximum leaf span of 15 cm. Therefore, treatment of larger planning target volumes, such as in nasopharyngeal cancer with traditional open and limited jaw technique, yields compromised dose distribution. Computed tomography data sets of 10 nasopharynx cancer patients were enrolled for the study. For each case, three separate treatment plans were generated viz. open, limited, and split x-jaw planning techniques with similar planning objectives. Only PTVs requiring a field size larger than 18 cm in the x-jaw position were considered. Comparable results were obtained regarding organs at risk (OAR) sparing in all the techniques. The target dose coverage with split x-jaw VMAT was superior to both open and limited jaw planning techniques, with a statistically significant difference in the intermediate dose planning target volumes (PTVs) (PTV59.4), P < 0.05. However, the split technique's dose to the spinal cord and larynx was significantly lower (P < 0.05). The split x-jaw planning technique of VMAT can be adapted for larger PTVs requiring an x-jaw of more than 15 cm. The only concern with this technique is the increased MU.

Digital technologies and mathematics teaching: An analysis of teacher professional knowledge

Professional teaching knowledge interferes with the planning and development of classes, which also relates to integrating digital technologies in the classroom. This study aimed to understand and discuss teachers’ professional knowledge for teaching mathematics with digital technologies. The methodology of this systematic literature review was composed of selecting 42 scientific articles in the ERIC, Latindex, Scopus, Scielo, and Web of Science databases and vertical and horizontal analyses of the indicated studies. The results suggest that the studies have similar structures with similar theoretical frameworks, objectives, and methodological procedures, identifying and classifying teacher professional knowledge based on knowledge achieved or that still needs to be developed. The teachers mobilize their knowledge by recognizing the potential of digital technologies for teaching mathematics critically and reflectively.

The Bombardment History of the Giant Planet Satellites

The origins of the giant planet satellites are debated, with scenarios including formation from a protoplanetary disk, sequential assembly from massive rings, and recent accretion after major satellite–satellite collisions. Here, we test their predictions by simulating outer solar system bombardment and calculating the oldest surface ages on each moon. Our crater production model assumes the projectiles originated from a massive primordial Kuiper Belt (PKB) that experienced substantial changes from collisional evolution, which transformed its size frequency distribution into a wavy shape, and Neptune’s outward migration, which ejected most PKB objects onto destabilized orbits. The latter event also triggered an instability among the giant planets some tens of Myr after the solar nebula dispersed. We find all giant planet satellites are missing their earliest crater histories, with the likely source being impact resetting events. Iapetus, Hyperion, Phoebe, and Oberon have surface ages that are a few Myr to a few tens of Myr younger than when Neptune entered the PKB (i.e., they are 4.52–4.53 Gyr old). The remaining midsized satellites of Saturn and Uranus, as well as the small satellites located between Saturn’s rings and Dione, have surfaces that are younger still by many tens to many hundreds of Myr (4.1–4.5 Gyr old). A much wider range of surface ages are found for the large moons Callisto, Ganymede, Titan, and Europa (4.1, 3.4, 1.8, and 0.18 Gyr old, respectively). At present, we favor the midsized and larger moons forming within protoplanetary disks, with the other scenarios having several challenges to overcome.

SiamATTRPN: Enhance Visual Tracking With Channel and Spatial Attention

Visual tracking is an important research topic in the field of computer vision. The current Siamese tracker based on the region proposal network (SiamRPN) has achieved promising tracking results in terms of efficiency and performance. However, through our empirical study, we have observed that deep features learned by SiamRPN are of substandard quality, as the salient regions within the deep features fail to correspond accurately with meaningful objects. To address this limitation, we propose an approach to enhance the quality of the learned deep features through the incorporation of an attention mechanism. Attention mechanisms have been shown to be effective in distinguishing similar objects, as they suppress background objects while highlighting target information that is most relevant. As a result, a new tracking method with channel and spatial attention termed SiamATTRPN is explored. To verify the effectiveness of SiamATTRPN, experiments on benchmark datasets demonstrate that our proposed tracker outperforms the baseline tracker significantly.

Highly efficient recognition of similar objects based on ionic robotic tactile sensors

Tactile sensing provides robots the ability of object recognition, fine operation, natural interaction, etc. However, in the actual scenario, robotic tactile recognition of similar objects still faces difficulties such as low efficiency and accuracy, resulting from a lack of high-performance sensors and intelligent recognition algorithms. In this paper, a flexible sensor combining a pyramidal microstructure with a gradient conformal ionic gel coating was demonstrated, exhibiting excellent signal-to-noise ratio (48 dB), low detection limit (1 Pa), high sensitivity (92.96 kPa−1), fast response time (55 ms), and outstanding stability over 15,000 compression-release cycles. Furthermore, a Pressure-Slip Dual-Branch Convolutional Neural Network (PSNet) architecture was proposed to separately extract hardness and texture features and perform feature fusion. In tactile experiments on different kinds of leaves, a recognition rate of 97.16% was achieved, and surpassed that of human hands recognition (72.5%). These researches showed the great potential in a broad application in bionic robots, intelligent prostheses, and precise human–computer interaction.

RayNet: A Simulation Platform for Developing Reinforcement Learning-Driven Network Protocols

Reinforcement Learning (RL) has gained significant momentum in the development of network protocols. However, RL-based protocols are still in their infancy, and substantial research is required to build deployable solutions. Developing a protocol based on RL is a complex and challenging process that involves several model design decisions and requires significant training and evaluation in real and simulated network topologies. Network simulators offer an efficient training environment for RL-based protocols, because they are deterministic and can run in parallel. In this paper, we introduce RayNet , a scalable and adaptable simulation platform for the development of RL-based network protocols. RayNet integrates OMNeT++, a fully programmable network simulator, with Ray/RLlib, a scalable training platform for distributed RL. RayNet facilitates the methodical development of RL-based network protocols so that researchers can focus on the problem at hand and not on implementation details of the learning aspect of their research. We developed a simple RL-based congestion control approach as a proof of concept showcasing that RayNet can be a valuable platform for RL-based research in computer networks, enabling scalable training and evaluation. We compared RayNet with ns3-gym , a platform with similar objectives to RayNet, and showed that RayNet performs better in terms of how fast agents can collect experience in RL environments.

Business center at 69 Dekabristov street: history first

Interaction between new projects and historical buildings is explored on the example of the business center at 69 Dekarbistov Street. The role of this business center in the structure of the historically significant area in Yekaterinburg is established through analysis of its spatial and urban compositions, and plastic and coloristic solutions. Opinions from practicing architects and architecture theorists have enabled general architectural and artistic approaches to the design of new architectural objects in historical contexts and criteria for their analysis to be formulated. A review of similar objects from Russian and international practice provided an evaluation scale with two opposite values: "full contrast" and "full nuance" of architectural solutions for a new facility in relation to the existing surrounding buildings. In conclusion, the importance of the business center is revealed as an object that harmoniously interacts with the historical environment and forms a corner of the city block.

Dwarf Planets Show Evidence of Recent Geologic Activity

Large bodies in the Kuiper Belt and beyond could have hosted subsurface oceans.

Cometary outbursts in the Oort cloud

Comet nuclei in the outer Solar system are constantly irradiated by cosmic rays at low temperatures. Accumulated high concentrations of radicals can undergo fast recombination with significant heating of cometary surface layers. We present the model of comet activity at large heliocentric distances caused by the recombination of radicals. We found that the considered mechanism can cause activity of comets in distant regions of the Solar system, even at the Oort cloud distances. Outbursts in distant comet reservoirs can be a new source of dust and ice particles contributing to the recently discovered anomalous diffuse light in the cosmic extragalactic background optic light and the unexpectedly high flux of dust particles detected by the New Horizons dust counter at the edge of the Kuiper belt. The orbits of small-radii comets in the Oort cloud are highly influenced by cometary outbursts. This effect may account for the observed decrease in the number of small-radius long-period comets.

SMILEtrack: SiMIlarity LEarning for Occlusion-Aware Multiple Object Tracking

Despite recent progress in Multiple Object Tracking (MOT), several obstacles such as occlusions, similar objects, and complex scenes remain an open challenge. Meanwhile, a systematic study of the cost-performance tradeoff for the popular tracking-by-detection paradigm is still lacking. This paper introduces SMILEtrack, an innovative object tracker that effectively addresses these challenges by integrating an efficient object detector with a Siamese network-based Similarity Learning Module (SLM). The technical contributions of SMILETrack are twofold. First, we propose an SLM that calculates the appearance similarity between two objects, overcoming the limitations of feature descriptors in Separate Detection and Embedding (SDE) models. The SLM incorporates a Patch Self-Attention (PSA) block inspired by the vision Transformer, which generates reliable features for accurate similarity matching. Second, we develop a Similarity Matching Cascade (SMC) module with a novel GATE function for robust object matching across consecutive video frames, further enhancing MOT performance. Together, these innovations help SMILETrack achieve an improved trade-off between the cost (e.g., running speed) and performance (e.g., tracking accuracy) over several existing state-of-the-art benchmarks, including the popular BYTETrack method. SMILETrack outperforms BYTETrack by 0.4-0.8 MOTA and 2.1-2.2 HOTA points on MOT17 and MOT20 datasets. Code is available at http://github.com/pingyang1117/SMILEtrack_official.

Mean orientation discrimination based on proximal stimuli.

Ensemble perception refers to the ability to accurately and rapidly perceive summary statistical representations of specific features from a group of similar objects. However, the specific type of representation involved in this perception within a three-dimensional (3-D) environment remains unclear. In the context of perspective viewing with stereopsis, distal stimuli can be projected onto the retina as different forms of proximal stimuli based on their distances, despite sharing similar properties, such as object size and spatial frequency. This study aimed to investigate the effects of distal and proximal stimuli on the perception of summary statistical information related to orientation. In our experiment, we presented multiple Gabor patches in a stereoscopic environment, allowing us to measure the discrimination threshold of the mean orientation. The object size and spatial frequency were fixed for all patches regardless of depth. However, the physical angular size and absolute spatial frequency covaried with the depth. The results revealed the threshold elevation with depth expansion, especially when the patches formed two clusters at near and far distances, leading to large variations in their retinotopic representations. This finding indicates a minor contribution of similarity of the distal stimuli. Subsequent experiments demonstrated that the variability in physical angular size of the patches significantly influenced the threshold elevation in contrast to that of binocular disparity and absolute spatial frequency. These findings highlight the critical role of physical angular size variability in perceiving mean orientations within the 3-D space.

Examination of archaeological bronze parts using micro-computed tomography and metallography

Abstract Archeological finds, such as old coins among which some show signs of corrosion, are, in general, unique pieces even though several copies exist of individual types. Subferrati, Roman coins with an iron core and a bronze coating, for instance, could be examined by conventional computed tomography (CT). The CT image allows an easy distinction of corrosion products, metallic iron, and the bronze so that appropriate sections could be selected from the images for metallography. The micro-CT technology even allows examining smaller archaeological objects to get an overview. The resolution of the micro-CT is a function of the object size and lies between 5 and 10 μm. The following metallographic examinations are intended to characterize the microstructure. Apart from these examinations, SEM analyses may also be performed on the sections. Different bronze pieces from cremation and inhumation burials were examined. Micro-CT provides a well recognizable contrast between corrosion products and the metallic bronze. If several similar objects exist, micro-CT examinations allow a decision to be made on which parts are suitable for metallographic analyses and which are not.

More realistic planetesimal masses alter Kuiper belt formation models and add stochasticity

Much of the modern Kuiper belt is thought to be the result of Neptune’s migration through a primordial belt of planetesimals, possibly interrupted by an instability amongst the giant planets. While most prior work has employed massless test particles to study this Kuiper belt formation process, we perform simulations here that include the gravitational effects of the primordial planetesimal belt consisting of ∼105 massive bodies. In our simulations, Neptune unlocks from resonance with the other giant planets and begins to migrate outward due to interactions with planetesimals before a planetary orbital instability is triggered, and afterward, residual Neptunian migration completes the formation of the modern Kuiper belt. Compared to past simulations using massless test particles, our present work exhibits a number of notable differences. First, Neptune’s planetary resonance unlocking requires the Neptunian 3:2 mean motion resonance to sweep much of the primordial disk interior to 30 au prior to the giant planet instability. This generates a pre-instability population of planetesimals that is significantly lower in semimajor axis, eccentricity, and inclination than predicted by many prior models, and this effect persists after the instability. Second, direct scattering between Pluto-mass bodies and other small bodies removes material from Neptunian resonances significantly more efficiently than the resonant dropout resulting from small changes in Neptune’s semimajor axis during scattering between Pluto-mass bodies and Neptune. Consequently, the primordial population of Pluto-mass bodies may be as few as ∼200 objects. Finally, our simulation end states display a wide variety of orbital distributions, and straightforward relationships between final bulk Kuiper belt properties and Neptune’s migration or initial planetesimal properties largely elude us. In particular, we find that the rapid, stochastic planetary orbital evolution occurring during the giant planet instability can significantly alter final Kuiper belt properties such as its inclination dispersion and the prominence of resonant populations. This complicates efforts to use modern Kuiper belt properties to confidently constrain early solar system events and conditions, including planetary orbital migration and the primordial Kuiper belt’s characteristics.

Comparative Evaluation of the 12th Grade Chemistry Curriculum According to The CIPP Evaluation Model “Türkiye and Nigeria”

This study aims to evaluate and compare the 12th-grade chemistry curriculum applied in high schools in Nigeria and Türkiye according to the CIPP evaluation model. mixed method was used in this study. The five-Likert scale Google form questionnaire prepared by the researcher in English and Turkish language was randomly applied in the high schools across Nigeria and Türkiye through mail, social media and other means of communication. In Nigeria, 203 whiles, in Türkiye, 162 of the 12thgrade chemistry teachers participated in the quantitative part of this study. In the qualitative part of the study, semi-structured interview questions which were prepared in English and Turkish were used to collect the opinions of participants across both countries. In Nigeria, five chemistry teachers participated in the study, while in Türkiye, three 12th-grade chemistry teachers participated. The collected quantitative data from the Google form were transferred to the SPPS data analysis software and analyzed. The data collected through semi-structured interviews were analyzed using descriptive analysis by transcribing the respondents’ quotations. According to the findings of this study, both countries have similar aims and objectives for the 12th-grade chemistry curriculum. However, it was revealed that there is a difference between the two countries in terms of reaching the general goals of the curriculum. It was revealed that, in Nigeria, the educational system does not allow teachers to implement the curriculum effectively. The theoretical information in the chemistry textbooks was found to be sufficient in Nigeria while insufficient in Türkiye. It was found that in Nigeria, the language used in chemistry textbooks is difficult and complex, while in Türkiye, there are insufficient laboratories in the schools, which negatively affects the implementation of the chemistry curriculum. In the product and process dimensions, it was found that there are no significant differences between the two countries. It was recommended that chemistry curriculums in both countries should be reviewed and updated every year to fit in the new age of science and technology. Laboratories should be available in all schools in Türkiye, while in Nigeria, simple language should be used in preparing chemistry curriculums.

Differential contributions of the hippocampal dentate gyrus and CA1 subfield to mnemonic discrimination.

Evidence suggests that individual hippocampal subfields are preferentially involved in various memory-related processes. Here, we demonstrated dissociations in these memory processes in two unique individuals with near-selective bilateral damage within the hippocampus, affecting the dentate gyrus (DG) in case BL and the cornu ammonis 1 (CA1) subfield in case BR. BL was impaired in discriminating highly similar objects in memory (i.e., mnemonic discrimination) but exhibited preserved overall recognition of studied objects, regardless of similarity. Conversely, BR demonstrated impaired general recognition. These results provide evidence for the DG in discrimination processes, likely related to underlying pattern separation computations, and the CA1 in retention/retrieval.