Level Of Complexity Research Articles

Enhanced Satellite Analytics for Mussel Platform Census Using a Machine-Learning Based Approach

Mussel platforms are big floating structures made of wood (normally about 20 m × 20 m or even a bit larger) that are used for aquaculture. They are used for supporting the growth of mussels in suitable marine waters. These structures are very common near the Galician coastline. For their maintenance and tracking, it is quite convenient to be able to produce a periodic census of these structures, including their current count and position. Images from Earth observation satellites are, a priori, a convenient choice for this purpose. This paper describes an application capable of automatically supporting such a census using optical images taken at different wavelength intervals. The images are captured by the two Sentinel 2 satellites (Sentinel 2A and Sentinel 2B, both from the Copernicus Project). The Copernicus satellites are run by the European Space Agency, and the produced images are freely distributed on the Internet. Sentinel 2 images include thirteen frequency bands and are updated every five days. In our proposal, remote-sensing normalized (differential) indexes are used, and machine-learning techniques are applied to multiband data. Different methods are described and tested. The results obtained in this paper are satisfactory and prove the approach is suitable for the intended purpose. In conclusion, it is worth noting that artificial neural networks turn out to be particularly good for this problem, even with a moderate level of complexity in their design. The developed methodology can be easily re-used and adapted for similar marine environments.

Comparative immunohematological profile of <i>Pelophylax ridibundus</i> and <i>P. lessonae</i> (Amphibia: Ranidae) infected with hemoparasites

The direction of adaptive reactions of healthy and Hepatozoon spp.-infected green frogs from water bodies of the Nizhni Novgorod region with various hydrochemical conditions was studied. During the observation period, infection of pool frogs and an increase in the total population indicators of infection of male and female marsh frogs with Hepatozoon spp. were revealed. Hypertrophy of the morphometric parameters of infected blood erythrocytes compared with healthy cells was revealed in marsh frogs. The content of neutrophil granulocytes in the blood of infected marsh frogs was higher compared to healthy individuals, while the level of immune complexes did not differ. In infected pool frogs, an increase in the level of large immune complexes in the blood serum and the enlargement index was revealed compared to healthy ones against the background of a general decrease in the body’s resistance in conditions of severe pollution of their habitat with heavy metals and sulfates. For marsh frogs, a correlation was established between the proportion of infected erythrocytes and the content of myelocytes and young forms of neutrophils in the blood; while for pool frogs – with the content of neutrophils and the enlargement index of immune complexes. The method of multifactorial dispersion analysis revealed a significant influence of such factors as gender and the interaction of gender/infection with hemoparasites on the immune status of amphibians.

Mathematical Tools for Simulation of 3D Bioprinting Processes on High-Performance Computing Resources: The State of the Art

Three-dimensional (3D) bioprinting belongs to the wide family of additive manufacturing techniques and employs cell-laden biomaterials. In particular, these materials, named “bioink”, are based on cytocompatible hydrogel compositions. To be printable, a bioink must have certain characteristics before, during, and after the printing process. These characteristics include achievable structural resolution, shape fidelity, and cell survival. In previous centuries, scientists have created mathematical models to understand how physical systems function. Only recently, with the quick progress of computational capabilities, high-fidelity and high-efficiency “computational simulation” tools have been developed based on such models and used as a proxy for real-world learning. Computational science, or “in silico” experimentation, is the term for this novel strategy that supplements pure theory and experiment. Moreover, a certain level of complexity characterizes the architecture of contemporary powerful computational resources, known as high-performance computing (HPC) resources, also due to the great heterogeneity of its structure. Lately, scientists and engineers have begun to develop and use computational models more extensively to also better understand the bioprinting process, rather than solely relying on experimental research, due to the large number of possible combinations of geometrical parameters and material properties, as well as the abundance of available bioprinting methods. This requires a new effort in designing and implementing computational tools capable of efficiently and effectively exploiting the potential of new HPC computing systems available in the Exascale Era. The final goal of this work is to offer an overview of the models, methods, and techniques that can be used for “in silico” experimentation of the physicochemical processes underlying the process of 3D bioprinting of cell-laden materials thanks to the use of up-to-date HPC resources.

An UltraMNIST classification benchmark to train CNNs for very large images

Current convolutional neural networks (CNNs) are not designed for large scientific images with rich multi-scale features, such as in satellite and microscopy domain. A new phase of development of CNNs especially designed for large images is awaited. However, application-independent high-quality and challenging datasets needed for such development are still missing. We present the ‘UltraMNIST dataset’ and associated benchmarks for this new research problem of ‘training CNNs for large images’. The dataset is simple, representative of wide-ranging challenges in scientific data, and easily customizable for different levels of complexity, smallest and largest features, and sizes of images. Two variants of the problem are discussed: standard version that facilitates the development of novel CNN methods for effective use of the best available GPU resources and the budget-aware version to promote the development of methods that work under constrained GPU memory. Several baselines are presented and the effect of reduced resolution is studied. The presented benchmark dataset and baselines will hopefully trigger the development of new CNN methods for large scientific images.

Product of Traditional Chinese Medicine Longgui Yangxinwan Protects the Human Body from Altitude Sickness Damage by Reducing Oxidative Stress and Preventing Mitochondrial Dysfunction.

Yu Liu, Zhengyang Zhang, Yongting Luo, Peng An, Jingyi Qi, Xu Zhang, Shuaishuai Zhou, Yongzhi Li, Chong Xu, Junjie Luo, and Jiaping Wang. Product of traditional Chinese medicine longgui yangxinwan protects the human body from altitude sickness damage by reducing oxidative stress and preventing mitochondrial dysfunction. High Alt Med Biol. 00:00-00, 2024. Background: Plateau reaction, caused by high-altitude exposure, results in symptoms like headaches, dyspnea, palpitations, fatigue, shortness of breath, and insomnia due to reduced oxygen levels. Mitochondria are crucial for high-altitude acclimatization as they regulate oxygen metabolism and cellular energy, reducing oxidative stress and maintaining bodily functions. Methods: The study participants were randomly divided into placebo group, Rhodiola group and longgui yangxinwan (Original name: taikong yangxinwan) group, with 20 people in each group. Three groups of subjects were sampled at three time points (PI: pre-intervention; P-D1: high-altitude day 1; P-D7: high-altitude day 7), and blood pressure, blood oxygen, heart rate, hemoglobin, and red blood cell count were measured. The ATP content, mitochondrial DNA copy number, expression of mitochondria-related genes, reactive oxygen species (ROS), glutathione peroxidase (GSH-PX) and malondialdehyde (MDA) levels, and mitochondrial morphology were measured in blood at each time point. Results: Our study results demonstrate that longgui yangxinwan keeps the selected human physiological indicators stable and prevents mitochondrial dysfunction in the high altitude. Mechanically, longgui yangxinwan decreases the level of ROS in human serum, whereas increases the activity of the antioxidant enzyme GSH-PX. At high-altitude day 1 (P-D1) and high-altitude day 7 (P-D7), ROS in the placebo group were 1.5 and 2.2-fold higher than those of the longgui yangxinwan group, respectively. In addition, longgui yangxinwan enhances ATP production capacity, restores the levels of mitochondrial respiratory chain complexes, and effectively maintains mitochondrial morphology and integrity. At P-D1 and P-D7, the ATP levels in the longgui yangxinwan group were 19-fold and 26-fold higher than those in the placebo group, respectively. Conclusions: Our study highlights longgui yangxinwan as a potential drug for protecting humans from high-altitude damage by reducing oxidative stress and preventing mitochondrial dysfunction.

A biopsy-sized 3D skin model with a perifollicular vascular plexus enables studying immune cell trafficking in the skin

Human skin vasculature features a unique anatomy in close proximity to the skin appendages and acts as a gatekeeper for constitutive lymphocyte trafficking to the skin. Approximating such structural complexity and functionality in 3D skin models is an outstanding tissue engineering challenge. In this study, we leverage the capabilities of the digital-light-processing bioprinting to generate an anatomically-relevant and miniaturized 3D skin-on-a-chip (3D-SoC) model in the size of a 6 mm punch biopsy. The 3D-SoC contains a perfusable vascular network resembling the superficial vascular plexus of the skin and closely surrounding bioengineered hair follicles. The perfusion capabilities of the 3D-SoC enables the circulation of immune cells, and high-resolution imaging of the immune cell-endothelial cell interactions, namely tethering, rolling, and extravasation in real-time. Moreover, the vascular pattern in 3D-SoC captures the physiological range of shear rates found in cutaneous blood vessels and allows for studying the effect of shear rate on T cell trafficking. In 3D-SoC, as expected, in vitro-polarized T helper 1 (Th1) cells show a stronger attachment on the vasculature compared to naïve T cells. Both naïve and T cells exhibit higher retention in the low-shear zones in the early stages (<5 min) of T cell attachment. Interestingly, at later stages T cell retention rate becomes independent of the shear rate. The attached Th1 cells further transmigrate from the vessel walls to the extracellular space and migrate toward the bioengineered hair follicles and interfollicular epidermis. When the epidermis is not present, Th1 cell migration toward the epidermis is significantly hindered, underscoring the role of epidermal signals on T cell infiltration. Our data validates the capabilities of 3D-SoC model to study the interactions between immune cells and skin vasculature in the context of epidermal signals. The biopsy-sized 3D-SoC model in this study represents a new level of anatomical and cellular complexity, and brings us a step closer to generating a truly functional human skin with its tissue-specific vasculature and appendages in the presence of circulating immune cells.

(Mis)measurement of Political Content Exposure within the Smartphone Ecosystem

The affordances of the smartphone are shifting individuals toward ever smaller and more fragmented units of political experience. In this piece, we make use of a novel approach to granular assessment of political exposure on smartphones, revealing an incredible level of complexity in modern political content diets, somewhat at odds with simplifying assumptions commonly made by political communication research. Based on five million screen-recording frames taken from 119 smartphones over two weeks, we find clear challenges to three common assumptions in the literature, with clear impacts on new theories about fragmented political media use: Assumption (1) unique encounters with political content can be aggregated by tabulation as though they are equivalent experiences; (2) durations of exposure to political content can be aggregated (e.g., at a monthly or daily level) without regard for how those time units are clustered at smaller timescales; and (3) singular political formats or sources (particularly the news formats and sources) are sufficient proxies for measuring and manipulating overall political content exposure. Regarding the first and second assumptions, our findings suggest that the majority of political content exposure occurs in bursts of only a few potentially-forgettable seconds, and that the remainder follow a power-law curve that reemerges across apps and individuals, with extreme variability within and across individuals. Regarding the third assumption, we find the vast majority of political content is encountered from formats and sources other than news and social media. We articulate how these results fit within and augment literature focused on political content exposure.

Penerapan Konsep Walkability Skala Manusia Berbasis Kegiatan Pelajar dalam Kawasan Pendidikan

Walkability is one part of realizing sustainable and livable city planning and design. The education area is one of the areas in urban areas that has a complex and dynamic level of problems. The attraction of the educational function in an area causes a high movement of people and goods so that in its development various commercial functions grow in it. The M.A Turungku road corridor is part of the education area in Buol City. In the corridor there are various educational functions starting from the elementary, secondary, to upper levels. The pull of the existence of the educational function in the M.A Turungku road corridor has resulted in the growth of commercial functions followed by its impact on the decline in environmental quality. The decline in the quality of the physical environment that occurs in the M.A Turungku road corridor has an impact on the comfort of walking activities, especially for students in the corridor. Therefore, in this study, the improvement of walkability in the M.A Turungku road corridor will be studied through a human-scale approach based on student activities. The research approach uses a rationalistic approach with data collection techniques through systematic observation. The results of this study show that the comfort level of human sensing when walking on the M.A Turungku road corridor gets an uncomfortable value. Meanwhile, in the results of the analysis of pedestrian movements and behavior, during the day in segment 2 of the M.A Turungku road corridor, outdoor activities occur very dynamically where main activities, additional activities, and follow-up activities of pedestrians are formed.

Increased platelet-leucocyte complexes do not result in coagulation activation in plateletpheresis donors.

Although plateletpheresis donation is commonly accepted as a safe procedure, its influence on platelet function, coagulation system and fibrinolysis is not completely elucidated. In this study, we tried to assess the effects of plateletpheresis on donor's hemostasis system by measuring platelet activation, development of platelet-leukocyte aggregates, and coagulation activation. Prospective observational study. We used flow cytometry to determine the levels of platelet-monocyte complexes (PMC) and platelet-neutrophil complexes (PNC). sP-selectin and prothrombin fragment (PF) 1 + 2 values were determined by ELISA. The PMC levels increased significantly seven days after apheresis in comparison with just after apheresis and 24 h after apheresis (p < 0.05). The PNC levels increased significantly seven days after apheresis compared to immediately after apheresis (p < 0.05). sP-selectin values decreased significantly immediately after apheresis (p < 0.05). While sP-selectin values increased seven days after apheresis in comparison with immediately after apheresis and 24 h after apheresis, but there were not statistically significant differences for sP-selectin levels (p > 0.05). PF1 + 2 levels decreased significantly immediately after apheresis compared to pre-apheresis (p < 0.05) and increased 24 h after apheresis and seven days after apheresis, but these differences were not statistically significant. We concluded that plateletpheresis affects platelet activation but does not cause any change in coagulation activation.

Object Registration Techniques For 3D Particle Tracking

Image based 3D particle tracking is currently the most widely used technique for volumetric velocity measurements. Inspecting the flow-field around an object is however, hampered by the latter, obstructing the view across it. In this study, the problem of measurement limitations due to the above is addressed. The present work builds upon the recent proposal from Wieneke and Rockstroh (2024), whereby the information of the occluded lines of sight can be incorporated into the particle tracking algorithm. The approach, however, necessitates of methods that accurately evaluate the shape and position of the object within the measurement domain. Methods of object marking and the following 3D registration of a digital object model (CAD) are discussed. For the latter, the Iterative Closest Point (ICP) registration algorithm is adopted. The accuracy of object registration is evaluated by means of experiments, where marking approaches that include physical and optically projected markers are discussed and compared. Three objects with growing level of geometrical complexity are considered: a cube, a truncated wing and a scaled model of a sport cyclist. The registered CAD representations of the physical objects are included in aerodynamic experiments, and the flow field is measured by means of large-scale particle tracking using helium filled soap bubbles. Three operating regimes are studied and compared: monolithic, partitioned and object-aware (OA) monolithic. The results indicate that object registration enables a correct reconstruction of particle tracers and strongly reduces the domain clipping typical of the monolithic approach. Furthermore, the dynamical use of all views in the OA monolithic method offers clear benefits compared to the partitioned approach, namely a lower occurrence of ghost particles. Finally, the combined visualization of the object and the surrounding flow pattern offers means of insightful data inspection and interpretation, along with posing a basis for PIV data assimilation at the fluid-solid interface.

Object Registration Techniques For 3D Particle Tracking

Image based 3D particle tracking is currently the most widely used technique for volumetric velocity measurements. Inspecting the flow-field around an object is however, hampered by the latter, obstructing the view across it. In this study, the problem of measurement limitations due to the above is addressed. The present work builds upon the recent proposal from Wieneke and Rockstroh (2024), whereby the information of the occluded lines of sight can be incorporated into the particle tracking algorithm. The approach, however, necessitates of methods that accurately evaluate the shape and position of the object within the measurement domain. Methods of object marking and the following 3D registration of a digital object model (CAD) are discussed. For the latter, the Iterative Closest Point (ICP) registration algorithm is adopted. The accuracy of object registration is evaluated by means of experiments, where marking approaches that include physical and optically projected markers are discussed and compared. Three objects with growing level of geometrical complexity are considered: a cube, a truncated wing and a scaled model of a sport cyclist. The registered CAD representations of the physical objects are included in aerodynamic experiments, and the flow field is measured by means of large-scale particle tracking using helium filled soap bubbles. Three operating regimes are studied and compared: monolithic, partitioned and object-aware (OA) monolithic. The results indicate that object registration enables a correct reconstruction of particle tracers and strongly reduces the domain clipping typical of the monolithic approach. Furthermore, the dynamical use of all views in the OA monolithic method offers clear benefits compared to the partitioned approach, namely a lower occurrence of ghost particles. Finally, the combined visualization of the object and the surrounding flow pattern offers means of insightful data inspection and interpretation, along with posing a basis for PIV data assimilation at the fluid-solid interface.

Preparation, characterization, single-crystal analysis, and cytotoxic assessment of complexes formed by Schiff base and 8-hydroxyquinoline co-ligand with Co(II), Ni(II), and Mn(II) metal ions

This study focuses on the preparation of mixed ligand complexes of Ni(II), Co(II), and Mn(II) by combining the co-ligands 2-(((4-fluorophenyl)imino)methyl)-4-methoxy-6-nitrophenol (L1) and 8-hydroxyquinoline (L2). The chemical structures of the all compounds were examined using various techniques, including 1H and 13C NMR, FT-IR, UV–Vis, TGA, molar conductivity, LC-MS/MS, elemental analysis and magnetic susceptibility. The crystal structure of the ligand L1 was determined using single crystal X-ray analysis revealing that the ligand favors the phenol-imine tautomeric form in the solid state. All complexes are suggested to have an octahedral structure. Finally, the MTT assay was used to determine the toxicity level of the mixed ligand complexes in human non-small cell lung cancer (A549) and normal bronchial epithelial cell lines (BEAS-2B). The results showed that the [Ni(L1)(L2).(H2O)2] complex (IC50: 5.97 µM) exhibited high cytotoxic activity at a lower dose than cisplatin compared to the other compounds. In contrast, the [Ni(L1)(L2).(H2O)2] complex was shown to exhibit significantly lower cytotoxic activity (IC50 > 100 s µM) in the BEAS-2B (normal bronchial epithelial cell) cell line. The other compounds [Co(L1)(L2).(H2O)2] and [Mn(L1)(L2).(H2O)2] were shown to have no significant anticancer activity in A549 cells due to their cytotoxic activity at higher doses than cisplatin (IC50 > 100 s µM).

Environment in the views of preschool children: an investigation of children’s drawings and narratives in Turkey

ABSTRACT The environment consists of different interrelated elements including biotic, abiotic, and anthropic. It is essential to understand the interrelations between these systems to be able solve environmental problems (e.g. climate change, pollution). In particular, it is necessary to develop such a systematic vision of the environment from the childhood years to raise them as environmentally conscious citizens. This study focused on preschoolers’ (5-year-old children) systematic vision and feelings regarding the environment in Samsun, which is the central city in the north region of Turkey. Data were collected from 51 children from three different preschools through their drawings and short interviews and then analysed with content analysis. As a result, findings presented the biotic, abiotic, and anthropic elements in their drawings. It was revealed that the majority of the children have a high level of complexity in their vision by representing different elements of the environment together. Moreover, children’s feelings reflected in their drawings were also analysed and reached as happiness, love, and responsibility. It was concluded that children’s social and emotional development can be supported through natural environment.

The immiscible to miscible transition and its consequences for 3-phase displacements in porous media of arbitrary wettability: Basic theory

In this paper, a “process-based” 3-phase model is applied to explore how multiphase fluid flow behaviour in two non-uniform wettability systems, named weakly oil-wet (WOW) and mixed-wet large (MWL), change when gas and oil move towards miscibility (σgo → 0). In the course of the theoretical development, we indicate how parts of the theory have been validated and confirmed satisfactorily by summarising experimental data from the literature. To demonstrate how the complexities of the three-phase physics interact with the system wettability, we use a capillary bundle (CB) model for the porous medium. This is sufficient to show the main processes which occur in the transition from immiscible to miscible behaviour. Even although the CB model is the simplest possible case for a porous medium, the results demonstrate a high level of unpredictable complexity which cover key parameters of the physics of 3-phase flow within porous media. In addition, for each case, the results point to the specific physical parameter that controls the phase separation lines. In some cases, gas injection or oil injection in a WOW system, the phase displacement changes quite radically as the system goes towards miscibility since there is a transition in wetting order from O/W/G to O/G/W. The differences and similarities between saturation paths in WOW and MWL are described in detail. For a given pore size distribution (PSD), the 3-phase displacements are controlled by the parameters of the rock wettability structure (see text) and the 3 interfacial tensions. Moving towards miscibility, 3-phase fluid displacement for gas injection and oil invasion are controlled by IFTs, while for water flooding, wettability structure plays the key role at all miscibility conditions. Although the simple CB model cannot describe all phenomena, such as phase trapping, the phase displacement paths, still the pore occupancies are qualitatively correct. Results of various phase injection in WOW are broadly consistent with pore occupancy sequences observations from pore scale X-Ray image analysis in literature despite simplicity of the theory which is validated in terms of its underling physics.

Rethinking informal workplace learning in times of complexity

Purpose Fast-changing global environment, hybrid and virtual work, today’s workplace is confronted to an unprecedented level of complexity. This conceptual paper aims to explore ways to re-think and adapt informal workplace learning to those recent changes and important dimensions to consider when designing successful learning strategies in the future. Design/methodology/approach To let emerge interesting tensions and explore new ways to approach informal workplace learning, the authors first look at recent trends in the workplace environment, then go back to some key concepts and ideas from the literature on informal learning. The authors then present two real-life cases they experimented with as scholar-practitioners that demonstrate the importance of a relational learning environment that encompasses virtuality, adaptive challenges and vertical development. Findings The new environment calls for new ways to think about informal workplace learning and how to support it. More than ever, organisations should support a culture that promotes collaboration and interactions across areas of expertise, a key condition for finding solutions to complex problems. In this complex environment, where there is no one right solution, organisations will need to rely on leaders who can become role models and show others how to overcome the silo mentality, engage into collaborative reflections, generate alternatives, experiment and learn quickly from what does or does not work. Originality/value This study contributes to the literature about workplace learning. It extends the understanding of some benefits that informal workplace learning provides to employees in an attempt to become agile practitioners as the work environment quickly changes and becomes more complex.

Effects of dabigatran, rivaroxaban, and apixaban on fibrin network permeability, thrombin generation, and fibrinolysis

Introduction There are important pharmacological differences between direct oral anticoagulants (DOAC) and a deeper knowledge of how they influence different aspects of hemostasis in patients on treatment is desirable. Materials and methods Blood samples from patients on dabigatran (n = 23), rivaroxaban (n = 26), or apixaban (n = 20) were analyzed with a fibrin network permeability assay, a turbidimetric clotting and lysis assay, the calibrated automated thrombogram (CAT), plasma levels of thrombin-antithrombin complex (TAT) and D-dimer, as well as DOAC concentrations, PT-INR and aPTT. As a comparison, we also analyzed samples from 27 patients on treatment with warfarin. Results Patients on dabigatran had a more permeable fibrin network, longer lag time (CAT and turbidimetric assay), and lower levels of D-dimer in plasma, compared with patients on rivaroxaban- and apixaban treatment, and a more permeable fibrin network than patients on warfarin. Clot lysis time was slightly longer in patients on dabigatran than in patients on rivaroxaban. Warfarin patients formed a more permeable fibrin network than patients on apixaban, had longer lag time than patients on rivaroxaban (CAT assay), and lower peak thrombin and ETP compared to patients on treatment with both FXa-inhibitors. Conclusions Results from this study indicate dabigatran treatment is a more potent anticoagulant than apixaban and rivaroxaban. However, as these results are not supported by clinical data, they are probably more related to the assays used and highlight the difficulty of measuring and comparing the effect of anticoagulants.

Analysis of MR–VR tele-operation methods for legged-manipulator robots

The development of immersive technologies in recent years has facilitated the control and execution of tasks at a high level of complexity in robotic systems. On the other hand, exploration and manipulation tasks in unknown environments have been one of the main challenges in search and rescue (SAR) robotics. Due to the complexity and uncertainty involved in autonomous manipulation tasks in unstructured environments, these are usually tele-operated initially. This article addresses a comparative study between Mixed Reality (MR—Hololens) and Virtual Reality (VR—HTC-Vive) methods for teleoperating legged-manipulator robots in the context of search and rescue. For this purpose, a teleoperation robotics method was established to address the comparison, developing VR–MR interfaces with the same contextualization and operational functionality for mission management and robot control of a robotic set composed of a quadrupedal robot equipped with a 6 degrees of freedom (6DoF) manipulator, by a user using hand gestures. A set of metrics is proposed for the comparative evaluation of the interfaces considering parameters that allow analyzing operability in the context of the mission (latencies, physical parameters of the equipment, etc.), as well as from the aspect of operator performance (required training, confidence levels, etc.). The experimental phase was conducted using both on-site and remote operations to evaluate and categorize the advantages and disadvantages of each method.

Large-Scale Indoor Camera Positioning Using Fiducial Markers.

Estimating the pose of a large set of fixed indoor cameras is a requirement for certain applications in augmented reality, autonomous navigation, video surveillance, and logistics. However, accurately mapping the positions of these cameras remains an unsolved problem. While providing partial solutions, existing alternatives are limited by their dependence on distinct environmental features, the requirement for large overlapping camera views, and specific conditions. This paper introduces a novel approach to estimating the pose of a large set of cameras using a small subset of fiducial markers printed on regular pieces of paper. By placing the markers in areas visible to multiple cameras, we can obtain an initial estimation of the pair-wise spatial relationship between them. The markers can be moved throughout the environment to obtain the relationship between all cameras, thus creating a graph connecting all cameras. In the final step, our method performs a full optimization, minimizing the reprojection errors of the observed markers and enforcing physical constraints, such as camera and marker coplanarity and control points. We validated our approach using novel artificial and real datasets with varying levels of complexity. Our experiments demonstrated superior performance over existing state-of-the-art techniques and increased effectiveness in real-world applications. Accompanying this paper, we provide the research community with access to our code, tutorials, and an application framework to support the deployment of our methodology.

Unravelling the spatiotemporal variation in the water levels of Poyang Lake with the variational mode decomposition model

AbstractPoyang Lake is a dynamic floodplain lake system that exhibits complex water level fluctuations and experiences significant regime changes over space and time, which remains to be further explored. This study used the variational mode decomposition (VMD) model to decompose the Poyang Lake's water levels from 1960 to 2022 at four key stations into six intrinsic mode functions (IMFs), namely IMF1–IMF6, representing variations on different time scales. The results present significant spatiotemporal heterogeneity. The multi‐year variation (IMF1) accounts for 5.6%–12.4% of the total variation and displays a northward decreasing trend, reflecting the lake's river‐like characteristics. The spectrum of IFM1 also reveals a significant 3.6‐year fluctuation mainly attributed to the tributary inflow, especially the Ganjiang River. The IMF1 differences between stations show abrupt decreases since the 2000s, indicating the impact of concentrated sand mining activities on the northern and central regions. The annual variation (IMF2) is the most prominent, contributing 76.1%–88.4% of the total variation, and shows a southward attenuation trend, likely due to the weakening influence of the Yangtze River flow. The intra‐annual scale (IMF3–IMF6) represents 6.0%–11.5% of the total variation and exhibits less spatial difference compared to the multi‐year and annual variations. The VMD model effectively separates the water level signals into different frequency bands, providing insights into the complex interactions between the lake, tributaries, and Yangtze River, as well as the impacts of human activities like sand mining, enhancing understanding of floodplain lake dynamics. The results also imply the importance of coping with the water level decline of Poyang Lake.

Estimation of the lateral mis-registrations of the GRAVITY+ adaptive optics system

Context. The GRAVITY+ upgrade implies a complete renewal of its adaptive optics (AO) systems. Its complex design, featuring moving components between the deformable mirrors and the wavefront sensors, requires the monitoring and auto-calibrating of the lateral mis-registrations of the system while in operation. Aims. For preset and target acquisition, large lateral registration errors must be assessed in open loop to bring the system to a state where the AO loop closes. In closed loop, these errors must be monitored and corrected, without impacting the science. Methods. With respect to the first requirement, our method is perturbative, with two-dimensional modes intentionally applied to the system and correlated to a reference interaction matrix. For the second requirement, we applied a non-perturbative approach that searches for specific patterns in temporal correlations in the closed loop telemetry. This signal is produced by the noise propagation through the AO loop. Results. Our methods were validated through simulations and on the GRAVITY+ development bench. The first method robustly estimates the lateral mis-registrations, in a single fit and with a sub-subaperture resolution while in an open loop. The second method is not absolute, but it does successfully bring the system towards a negligible mis-registration error, with a limited turbulence bias. Both methods proved to robustly work on a system still under development and not fully characterised. Conclusions. Tested with Shack-Hartmann wavefront sensors, the proposed methods are versatile and easily adaptable to other AO instruments, such as the pyramid, which stands as a baseline for all future AO systems. The non-perturbative method, not relying on an interaction matrix model and being sparse in the Fourier domain, is particularly suitable to the next generation of AO systems for extremely large telescopes that will present an unprecedented level of complexity and numbers of actuators.