Shape Changes Research Articles

A Multiscale Parallel Pedestrian Recognition Algorithm Based on YOLOv5

Mainstream pedestrian recognition algorithms have problems such as low accuracy and insufficient real-time performance. In this study, we developed an improved pedestrian recognition algorithm named YOLO-MSP (multiscale parallel) based on residual network ideas, and we improved the network architecture based on YOLOv5s. Three pooling layers were used in parallel in the MSP module to output multiscale features and improve the accuracy of the model while ensuring real-time performance. The Swin Transformer module was also introduced into the network, which improved the efficiency of the model in image processing by avoiding global calculations. The CBAM (Convolutional Block Attention Module) attention mechanism was added to the C3 module, and this new module was named the CBAMC3 module, which improved model efficiency while ensuring the model was lightweight. The WMD-IOU (weighted multidimensional IOU) loss function proposed in this study used the shape change between the recognition frame and the real frame as a parameter to calculate the loss of the recognition frame shape, which could guide the model to better learn the shape and size of the target and optimize recognition performance. Comparative experiments using the INRIA public data set showed that the proposed YOLO-MSP algorithm outperformed state-of-the-art pedestrian recognition methods in accuracy and speed.

Effect of Heat Treatment on the Supramolecular Structure of Copolymers Based on Poly(propylene glycol fumarate phthalate) with Acrylic Acid

Previous studies investigating the thermal decomposition of p-PGFPh:AA copolymers in an inert atmosphere have provided only a general understanding of the changes that occur during thermolysis. Comprehensive studies are required to gain a better understanding of these processes [1]. The most comprehensive information on the influence of various factors on both the kinetics and the supramolecular structure of the resulting products can be obtained by combining the method of thermal analysis with IR, mass spectrometry, and scanning electron microscopy. The compounds studied have two different compositions, namely p‑PGFPh:AA 6.77:93.23 mol % and p-PGFPh:AA 86.67:13.33 mol %. These compounds were then subjected to a thermolysis process, which resulted in the emission of gases and a decrease in sample weight. The degradation process can be divided into three stages: 1) Depolymerization of the main chain; 2) Depolymerization of the side chain; 3) Final decomposition. These processes occur sequentially at different temperature ranges. According to TG- and DTG studies, complete decomposition of p-PGFPh:AA copolymers occurred at Tterm = 340–350 °C. In this temperature range, a slight loss of sample mass (less than 10 wt %) was observed along with a slight gas evolution. The main gaseous products from the transformation of the studied samples were CO and CO2. This was supported by IR-CO (2000–2200 cm−1) and CO2 (2310–2370 cm−1) as well as mass spectrometric observations. The final products resulting from the thermolysis of p-PGFPh:AA copolymers were examined under an electron microscope. The results showed a similar morphological pattern of mesostructures with sizes ranging from 0.3–1.5 μm, which were observed depending on the porous structure of the initial polymer material. Based on the experimental data, it can be concluded that the p-PGFPh:AA copolymers (in proportions of 6.77:93.23 mol % and 86.67:13.33 mol %) have a relatively high degree of resistance to heating and do not undergo any changes in chemical composition, particle size and shape. In conclusion, the results clearly indicate that the selection of conditions for pyrolysis plays a crucial role in increasing the thermal stability of polymeric materials. This method allows for purposeful changes in the structure and properties of polymers.

Proxy-SU(4) symmetry in A = 60–90 region

Applications of the proxy-SU(3) model of Bonatsos and collaborators to nuclei in A = 60–90 region introduces proxy-SU(4) symmetry. Shell model spaces with single particle orbits 1 p 3/2, 1 p 1/2, 0 f 5/2 and 0 g 9/2 are essential for these nuclei and also protons and neutrons in this region occupy the same single particle orbits. With this and applying the ‘proxy scheme’, the 0 g 9/2 changes to 0 f 7/2 giving the spectrum generating algebra U(40) ⊃ [U(10) ⊃ G ⊃ SO(3)] ⨂ [SU ST (4) ⊃ SU S (2) ⨂ SU T (2)]. With G = SU(3), we have the proxy-SU(3) model. It is easy to see that proxy-SU(3) symmetry implies goodness of the SU(4) symmetry appearing above, i.e. proxy-SU(4) symmetry. Shell model calculations pointing out the need for 0 g 9/2 orbit, ground state masses, shape changes and shape co-existence in A = 60–90 region and GT distributions clearly show the importance of proxy-SU(4) in this mass region. Besides presenting this evidence, new proxy schemes with G = SU(5), SO(6) and SO(10) that are generated by good proxy-SU(4) symmetry are described in some detail. An important feature is that the four proxy symmetries SU(3), SO(6), SU(5) and SO(10) appear twice.

Using public-sourced photos to track changes in moose antler size during a 20-year hunting ban

Hunting directly impacts the population dynamics of ungulates and can have a significant effect on the quality of phenotypic traits such as horns or antlers. In Poland, following a demographic collapse in the 1990s and the introduction of a hunting ban in 2001, the population of moose (Alces alces) has increased from 1,800 to over 20,000 individuals, recolonising its former range. As the moose is a charismatic species and a popular subject for nature photography, we analysed changes in antler size and shape in this cervid between 2005 and 2021 based on photos of male moose and antler casts provided by photographers or available in social media. Our findings indicate that during the hunting ban, the probability of observing the cervina antler type significantly decreased over time, from 47% in 2012 to 28% in 2021. Meanwhile, the probability of observing the intermediate and palmate antler types significantly increased from 44 to 53% and from 9 to 19%, respectively. The mean number of tines significantly increased from 3.2 in 2005 to 4.7 in 2021, and the antler size index significantly increased from 3.4 to 3.9. The most likely mechanism behind the observed changes could be the ageing of a population released from hunting pressure. We also observed regional variation in antler size, which is likely related to differences in environmental conditions. Our study serves as an example of how passive citizen science can contribute to our understanding of ecological trends and the quantification of population patterns. It also has important implications for management of species affected by trophy hunting.

Ultraviolet–Visible-Near InfraRed spectroscopy for assessing metal powder cross-contamination: A multivariate approach for a quantitative analysis

The last few years have seen an increasing use of spherical metals powders to produce bulk parts through metal forming technologies like Additive Manufacturing and Metal Injection Molding. This, coupled with the wide availability of metal powders, leads to a critical issue: contamination across different systems in different process steps. Consequently, it is necessary to find a new, fast, and reliable analysis sensible to tiny traces of contamination. This work evaluates the applicability of Ultraviolet–Visible-Near InfraRed (UV–Vis-NIR) spectroscopy, a technique providing information on powders’ reflectance, for studying contaminated powders. This work focuses on assessing 3 binary systems obtained from the cross-contamination of 3 components (A92618, C10200 and S31603) in a low contamination range (from 0.5 vol% to vol. 6%) and in a high contamination range (25 vol% and vol.50%). After the UV–Vis-NIR analysis, multivariate analysis has been used to obtain quantitative results. Results show that, as the contamination level increases in the binary system, the shape of spectra changes and becomes progressively more similar to the contaminant one. The chemometric analysis allows the detection of the contaminant type and its concentration percentage in the contaminated powder.

A practical, step-by-step, guide to taxonomic comparisons using Procrustes geometric morphometrics and user-friendly software (part B): group comparisons

In this second part of the study, using a ‘clean’ dataset without very low precision landmarks and outliers, I describe how to compare mandibular size and shape using Procrustes methods in adult North American marmots. After demonstrating that sex differences are negligible, females and males are pooled together with specimens of unknown sex and species are compared using a battery of tests, that estimate both statistical significance and effect size. The importance of allometric variation and its potential effect on shape differences is also explored. Finally, to provide potential clues on founder effects, I compare the magnitude of variance in mandibular size and shape between the Vancouver Island marmot (VAN) and the hoary marmot, its sister species on the mainland. In almost all main analyses, I explore the sensitivity of results to heterogeneous sample size and small samples using subsamples and randomized selection experiments. For both size and shape, I find a degree of overlap among species variation but, with very few exceptions, mean interspecific differences are well supported in all analyses. Shape, in particular, is an accurate predictor of taxonomic affiliation. Allometry in adults, however, explains a modest amount of within-species shape change. Yet, there is a degree of divergence in allometric trajectories that seems consistent with subgeneric separation. VAN is the most distinctive species for mandibular shape and mandibular morphology suggests a long history of reduced variation in this insular population. Geometric morphometrics (GMM) is a powerful tool to aid taxonomic research. Regardless of the effectiveness of this family of methods and the apparent robustness of results obtained with GMM, however, large samples and careful measurements remain essential for accuracy. Even with excellent data, morphometrics is important, but its findings must be corroborated with an integrative approach that combines multiple lines of evidence to taxonomic assessment. The analytical protocol I suggest is described in detail, with a summary checklist, in the Appendix, not to miss important steps. All the analyses can be replicated using the entire dataset, which is freely available online. Beginners may follow all the steps, whereas more experienced researchers can focus on one specific aspect and read only the relevant chapter. There are limitations, but the protocol is flexible and easy to improve or implement using a programming language such as R.

Analysis of prefabricated myofunctional appliances with different overjet and bumper designs: a three-dimensional finite element analysis

BackgroundPrefabricated myofunctional appliance can guide tooth eruption, improve dentition alignment, correct myofunctional disorders and harmful oral habits. However, its application to skeletal discrepancy may result in unsatisfactory tooth inclination. This study aimed to construct a novel appliance with overjet design to avoid this side effect and investigated its shape and mechanical changes under occlusion using three-dimensional finite element method.MethodsWe established three samples of prefabricated myofunctional appliances. The first one was edge to edge without overjet, and the outer shield of both jaws were flattened. The second one was 3 mm overjet with stepped the outer shield. The last one was 3 mm overjet, and the outer shield of both jaws were flatted, which meant the front wall of lower jaw was strengthened with bumper, termed as lower bumper. A complete dentition model was applied to the study. 150 N occlusal force was applied to each type of appliance and the deformation displacement and the changes in stress was recorded.ResultsThe deformation was significant in the incisors regions, especially in the vertical and lateral dimensions. The maximum displacements of 3 mm overjet with step shield group were 7.08 mm (vertical), 3.99 mm (lateral), and 2.90 mm (sagittal), while it decreased to 3.92 mm(vertical), 1.94 mm (lateral), and 1.55 mm (sagittal) in overjet with bumper group. Moreover, the upper molar regions exhibited higher vertical and sagittal displacement in 3 mm overjet with step shield group, which were 3.03 mm (vertical) and 1.99 mm (sagittal), and the bumper design could decrease the maximum displacement to 1.72 mm (vertical) and 0.72 mm (sagittal). In addition, the Von Mises stress of appliances was analyzed, and results indicated that 3 mm overjet with step shield generated higher stress than other groups, with the maximum Von Mises stress was 0.9387 MP, which were 0.5858 and 0.5657 MP in edge to edge group and 3 mm overjet with lower bumper group, respectively.ConclusionThe prefabricated myofunctional appliances may cause deformation during occlusion. Compared to step shield group, the application of lower bumper exhibited better resistance to occlusal force.

Topological analysis of 3D digital ovules identifies cellular patterns associated with ovule shape diversity.

Tissue morphogenesis remains poorly understood. In plants, a central problem is how the 3D cellular architecture of a developing organ contributes to its final shape. We address this question through a comparative analysis of ovule morphogenesis, taking advantage of the diversity in ovule shape across angiosperms. Here, we provide a 3D digital atlas of Cardamine hirsuta ovule development at single cell resolution and compare it to an equivalent atlas of Arabidopsis thaliana. We introduce nerve-based topological analysis as a tool for unbiased detection of differences in cellular architectures and corroborate identified topological differences between two homologous tissues by comparative morphometrics and visual inspection. We find that differences in topology, cell volume variation and tissue growth patterns in the sheet-like integuments and the bulbous chalaza, are associated with differences in ovule curvature. In contrast, the radialized, conical ovule primordia and nucelli exhibit similar shapes despite differences in internal cellular topology and tissue growth patterns. Our results support the notion that the structural organization of a tissue is associated with its susceptibility to shape changes during evolutionary shifts in 3D cellular architecture.

Neuronal LRP4 directs the development, maturation, and cytoskeletal organization of Drosophila peripheral synapses.

Tissue morphogenesis remains poorly understood. In plants, a central problem is how the 3D cellular architecture of a developing organ contributes to its final shape. We address this question through a comparative analysis of ovule morphogenesis, taking advantage of the diversity in ovule shape across angiosperms. Here, we provide a 3D digital atlas of Cardamine hirsuta ovule development at single cell resolution and compare it to an equivalent atlas of Arabidopsis thaliana. We introduce nerve-based topological analysis as a tool for unbiased detection of differences in cellular architectures and corroborate identified topological differences between two homologous tissues by comparative morphometrics and visual inspection. We find that differences in topology, cell volume variation and tissue growth patterns in the sheet-like integuments and the bulbous chalaza, are associated with differences in ovule curvature. In contrast, the radialized, conical ovule primordia and nucelli exhibit similar shapes despite differences in internal cellular topology and tissue growth patterns. Our results support the notion that the structural organization of a tissue is associated with its susceptibility to shape changes during evolutionary shifts in 3D cellular architecture.

Exploration of dynamic phase transition of 3D Ising model with a new long-range interaction by using the Monte Carlo method

In this paper, we present a novel interpretation of the long-range interaction for exploring the magnetic characteristics of the 3D Ising model. To describe the long-range interaction, we utilize spin chains, which enable us to explore the dynamic magnetic behaviors of this model. The research investigates the impacts of the amplitude of the time-dependent magnetic field h0 and period τ on the dynamic phase transition by obtaining phase diagrams and midplane cross-sections of the system. Critical exponents are also discussed, which are consistent with other theoretical results. The dynamic hysteresis behaviors are then examined through various physical parameters. As the temperature increases, the area and shape of the dynamic hysteresis loop change. Our theoretical conclusions are consistent with those of other theoretical and experimental studies.

Programmable, Self-Healable, and Photochromic Liquid Crystal Elastomers Based on Dynamic Hindered Urea Bonds for Biomimetic Flowers.

Recently, researchers have been exploring the use of dynamic covalent bonds (DCBs) in the construction of exchangeable liquid crystal elastomers (LCEs) for biomimetic actuators and devices. However, a significant challenge remains in achieving LCEs with both excellent dynamic properties and superior mechanical strength and stability. In this study, a diacrylate-functionalized monomer containing dynamic hindered urea bonds (DA-HUB) is employed to prepare exchangeable LCEs through a self-catalytic Michael addition reaction. By incorporating DA-HUB, the LCE system benefits from DCBs and hydrogen bonding, leading to materials with high mechanical strength and a range of dynamic properties such as programmability, self-healing, and recyclability. Leveraging these characteristics, bilayer LCE actuators with controlled reversible thermal deformation and outstanding dimensional stability are successfully fabricated using a simple welding method. Moreover, a biomimetic triangular plum, inspired by the blooming of flowers, is created to showcase reversible color and shape changes triggered by light and heat. This innovative approach opens new possibilities for the development of biomimetic and smart actuators and devices with multiple functionalities.

Synthetic silica fibers of different length, diameter and shape: synthesis and interaction with rat (NR8383) and human (THP-1) macrophages in vitro, including chemotaxis and gene expression profile

BackgroundInhalation of biopersistent fibers like asbestos can cause strong chronic inflammatory effects, often resulting in fibrosis or even cancer. The interplay between fiber shape, fiber size and the resulting biological effects is still poorly understood due to the lack of reference materials.ResultsWe investigated how length, diameter, aspect ratio, and shape of synthetic silica fibers influence inflammatory effects at doses up to 250 µg cm-2. Silica nanofibers were prepared with different diameter and shape. Straight (length ca. 6 to 8 µm, thickness ca. 0.25 to 0.35 µm, aspect ratio ca. 17:1 to 32:1) and curly fibers (length ca. 9 µm, thickness ca. 0.13 µm, radius of curvature ca. 0.5 µm, aspect ratio ca. 70:1) were dispersed in water with no apparent change in the fiber shape during up to 28 days. Upon immersion in aqueous saline (DPBS), the fibers released about 5 wt% silica after 7 days irrespectively of their shape. The uptake of the fibers by macrophages (human THP-1 and rat NR8383) was studied by scanning electron microscopy and confocal laser scanning microscopy. Some fibers were completely taken up whereas others were only partially internalized, leading to visual damage of the cell wall. The biological effects were assessed by determining cell toxicity, particle-induced chemotaxis, and the induction of gene expression of inflammatory mediators.ConclusionsStraight fibers were only slightly cytotoxic and caused weak cell migration, regardless of their thickness, while the curly fibers were more toxic and caused significantly stronger chemotaxis. Curly fibers also had the strongest effect on the expression of cytokines and chemokines. This may be due to the different aspect ratio or its twisted shape.

New species of Bryophaenocladius Thienemann, 1934 (Diptera: Chironomidae) from Argentina

Three new species of Bryophaenocladius Thienemann are described and figured as male imagines: B. urbanus sp. n. from Central Argentina, and B. virgotruncatus sp. n. and B. nasus sp. n. from Argentinean Patagonia. A geometric morphometric analysis was performed to evaluate the taxonomic value of the shape of the anal point in species delimitation. The analysis involved 96 species. As a result, the Bryophaenocladius species showed significant anal point patterns of shape change, recovering three main shape types: rounded, equilateral triangle-shaped, and isosceles triangle-shaped. An identification key of the Bryophaenocladius species from the Neotropical region is provided.

Comparison of Newtonian and glycerol-water solution-based SiO2 nanofluid droplets impacting on heated spherical surfaces

The dynamic interactions of liquid droplets with heated spherical particles, relevant across various scientific and engineering disciplines, display intriguing collision behaviors whose principles are yet to be fully deciphered. This investigation utilizes high-speed photography to explore the wetting and non-wetting responses of different Newtonian and glycerol-water solution-based SiO2 nanofluid droplets upon contact with heated particles. Findings indicate that nanofluid droplets disrupt the thermal field and modify the surface morphology of particles more extensively under wetting than non-wetting conditions. Wetting conditions lead to significant alterations in the liquid film thickness and notable velocity field disruptions for droplets of deionized water and glycerol solution. Conversely, in the non-wetting phase, droplets nearing full rebound cause less disturbance to the velocity field, a behavior consistent across all fluid types and particle temperatures. The shape changes nanofluid droplets undergo when rebounding and separating from the particle surface are similar to those seen in glycerol solution and water droplets. Droplets in the breakup-rebound phase experience shorter contact times than those merely rebounding. A phase diagram is presented, detailing wetting (receding-deposition and boiling-breakup) and non-wetting (rebound and breakup-rebound) actions. An increase in the Weber number necessitates a higher particle temperature for the transition from rebound to breakup-rebound, which corroborates with theoretical insights. Furthermore, droplets achieve their maximum spreading area during the boiling-breakup mode.

Development of smart materials with versatile bending capabilities using microcellular foaming process: influence of foaming and desorption time

Abstract Herein, a smart material with versatile bending capability is developed using a microcellular foaming process (MCPs). In contrast to previous hydrogel-based approaches, the bi-layered smart material is fabricated using typical thermoplastics, polyethylene terephthalate glycol (PETG) and polymethyl methacrylate (PMMA), to achieve shape deformation in response to thermal stimuli. Further, the theoretical model for bi-layered smart materials based on the modified Timoshenko’s model is employed to predict and comprehend this thermal response phenomenon. Due to the distinct foaming characteristics of the two polymers, a reversal in the bending direction is achieved by manipulating the foaming and desorption time. The length variation after foaming differs depending on the desorption time for each polymer. PMMA decreases in length after foaming, measuring 56.25 mm at a desorption time of 40 min and 53.16 mm at 80 min. On the other hand, PETG shows an increase in length after foaming, measuring 53.33 mm at 40 min and 58.25 mm at 80 min. Consequently, when the two polymers are bonded and foamed, bending occurs depending on the desorption time, and a reversal in the bending direction is observed at the critical desorption time of around 60 min. Based on this result, the folding direction of a five-leafed flower-shaped object is successfully altered under thermal stimuli. This innovative approach extends the category of smart materials beyond the hydrogels and showcases the potential of the MCPs for the creation of smart materials for various applications that require versatile shape changes in response to temperature.

ANALYSIS OF THE FORM AND SURFACE OF DENTAL IMPLANTS

The aim of the work – to study the peculiarities of the shape and surface relief of the main types of dental implants. Materials and methods. 12 dental implants used in the medical practice of Ukrainian dental clinics were studied. The study of the shape and surface relief of the implants was carried out using a scanning electron microscope GSM-649 (Japan). Results. All implants in the apical part have the shape of a cone with threads and cutting grooves. The thread with a large profile is located in the apical part of the implant, has an average pitch of turns of 1.1±0.05 mm and a profile height of 0.3±0.02 mm. The thread with a small profile is located in the part of the implant near the neck, has a pitch of 0.4±0.02 mm and a profile height of 0.1±0.02 mm. The thread pitch of implants with a single profile is 0.8±0.05 mm, and the height of the profile is 0.2±0.01 mm. Threads with a triangular profile have a profile angle of 50.0±2.9 degrees. The highest roughness is the surface of the top of the fine profile thread with the height of micro-uniformities from 7.0±2.2 to 36.0±8.3 μm, the smallest roughness with the height of micro-uniformities from 3.0±1.1 to 14.0±6.1 μm have surface areas in the area of the implant neck. Conclusions. 50% of the examined implants were made with two thread profiles: a large one in the apical side and a small one closer to the neck, 50% – with the same thread profile from the apical end to the neck. In most implants, the thread with a small profile is made in the form of annular grooves. The large thread of the implants had a rectangular, rounded and triangular profile with one or two steps. In some implants, as they approach the neck, the shape changes and the height of the thread profile decreases. The shape of the profile of small threads in all implants was close to rounded. The implants had different surface roughness. The highest roughness was recorded on the surface of the top of the small profile thread, and the lowest – in the area without a thread in the area of the implant neck.

An emerging role for tissue plasticity in developmental precision.

Reproducible tissue morphology is a fundamental feature of embryonic development. To ensure such robustness during tissue morphogenesis, inherent noise in biological processes must be buffered. While redundant genes, parallel signaling pathways and intricate network topologies are known to reduce noise, over the last few years, mechanical properties of tissues have been shown to play a vital role. Here, taking the example of somite shape changes, I will discuss how tissues are highly plastic in their ability to change shapes leading to increased precision and reproducibility.

Asymmetric fin shape changes swimming dynamics of ancient marine reptiles’ soft robophysical models

Animals have evolved highly effective locomotion capabilities in terrestrial, aerial, and aquatic environments. Over life’s history, mass extinctions have wiped out unique animal species with specialized adaptations, leaving paleontologists to reconstruct their locomotion through fossil analysis. Despite advancements, little is known about how extinct megafauna, such as the Ichthyosauria one of the most successful lineages of marine reptiles, utilized their varied morphologies for swimming. Traditional robotics struggle to mimic extinct locomotion effectively, but the emerging soft robotics field offers a promising alternative to overcome this challenge. This paper aims to bridge this gap by studying Mixosaurus locomotion with soft robotics, combining material modeling and biomechanics in physical experimental validation. Combining a soft body with soft pneumatic actuators, the soft robotic platform described in this study investigates the correlation between asymmetrical fins and buoyancy by recreating the pitch torque generated by extinct swimming animals. We performed a comparative analysis of thrust and torque generated by Carthorhyncus, Utatsusaurus, Mixosaurus, Guizhouichthyosaurus, and Ophthalmosaurus tail fins in a flow tank. Experimental results suggest that the pitch torque on the torso generated by hypocercal fin shapes such as found in model systems of Guizhouichthyosaurus, Mixosaurus and Utatsusaurus produce distinct ventral body pitch effects able to mitigate the animal’s non-neutral buoyancy. This body pitch control effect is particularly pronounced in Guizhouichthyosaurus, which results suggest would have been able to generate high ventral pitch torque on the torso to compensate for its positive buoyancy. By contrast, homocercal fin shapes may not have been conducive for such buoyancy compensation, leaving torso pitch control to pectoral fins, for example. Across the range of the actuation frequencies of the caudal fins tested, resulted in oscillatory modes arising, which in turn can affect the for-aft thrust generated.

The shape of fringing tidal flats in engineered estuaries

For the management of estuaries and the preservation of tidal flats it is crucial to understand the tidal flat shape and development. Previous work focused predominantly on the quasi-equilibrium shape of tidal flats along open coasts with a dominant cross-shore flow and wave exposure. This paper evaluates the shape of fringing tidal flats in engineered estuaries, where longshore velocities generally dominate. Using a long-term (20 years) topographic data set of an anthropogenically modified estuary in the Netherlands (the Western Scheldt estuary), we relate key profile shape parameters and changes over time to natural and anthropogenic processes. In an engineered estuary, the tidal flat shape depends on the estuary geometry, hydrodynamic forcings and human interventions. In contrast to open coast tidal flats, the presence of the channel and dominant longshore flow determines the available cross-shore length (accommodation space) of the tidal flat and the shape of the tidal flat. This accommodation space defines the maximum tidal flat height and opportunity for marsh development. We propose the use of the Index of Development, indicating to what extend tidal flats have space to develop. This index is not only influenced by longshore and cross-shore flow, but also (or even more) by hydraulic structures, dike realignments and channel migration. Especially the latter two strongly influence the accommodation space and thereby the maximum tidal flat height and the opportunity for marsh development. For large stretches of the Western Scheldt, the accommodation space is too small, and the majority of the tidal flats do not vertically extent to mean high water. The success of tidal flat and marsh restoration projects depends on the accommodation space.

Local and global changes in cell density induce reorganisation of 3D packing in a proliferating epithelium.

Tissue morphogenesis is intimately linked to the changes in shape and organisation of individual cells. In curved epithelia, cells can intercalate along their own apicobasal axes, adopting a shape named 'scutoid' that allows energy minimization in the tissue. Although several geometric and biophysical factors have been associated with this 3D reorganisation, the dynamic changes underlying scutoid formation in 3D epithelial packing remain poorly understood. Here, we use live imaging of the sea star embryo coupled with deep learning-based segmentation to dissect the relative contributions of cell density, tissue compaction and cell proliferation on epithelial architecture. We find that tissue compaction, which naturally occurs in the embryo, is necessary for the appearance of scutoids. Physical compression experiments identify cell density as the factor promoting scutoid formation at a global level. Finally, the comparison of the developing embryo with computational models indicates that the increase in the proportion of scutoids is directly associated with cell divisions. Our results suggest that apico-basal intercalations appearing immediately after mitosis may help accommodate the new cells within the tissue. We propose that proliferation in a compact epithelium induces 3D cell rearrangements during development.