Convex Edge Research Articles

Magnetization Reversal in Concave Iron Nano-Superellipses

Square magnetic nanodots can show intentional or undesired shape modifications, resulting in superellipses with concave or convex edges. Some research groups also concentrated on experimentally investigating or simulating concave nano-superellipses, sometimes called magnetic astroids due to their similarity to the mathematical shape of an astroid. Due to the strong impact of shape anisotropy in nanostructures, the magnetization-reversal process including coercive and reversibility fields can be expected to be different in concave or convex superellipses than that in common squares. Here, we present angle-dependent micromagnetic simulations on magnetic nanodots with the shape of concave superellipses. While magnetization reversal occurs via meander states, horseshoe states or the 180° rotation of magnetization for the perfect square, depending on the angle of the external magnetic field, more complicated states occur for superellipses with strong concaveness. Even apparently asymmetric hysteresis loops can be found along the hard magnetization directions, which can be attributed to measuring minor loops since the reversibility fields become much larger than the coercive fields.

A probabilistic segmentation and entropy-rank correlation-based feature selection approach for the recognition of fruit diseases

Agriculture plays a critical role in the economy of several countries, by providing the main sources of income, employment, and food to their rural population. However, in recent years, it has been observed that plants and fruits are widely damaged by different diseases which cause a huge loss to the farmers, although this loss can be minimized by detecting plants’ diseases at their earlier stages using pattern recognition (PR) and machine learning (ML) techniques. In this article, an automated system is proposed for the identification and recognition of fruit diseases. Our approach is distinctive in a way, it overcomes the challenges like convex edges, inconsistency between colors, irregularity, visibility, scale, and origin. The proposed approach incorporates five primary steps including preprocessing,Standard instruction requires city and country for affiliations. Hence, please check if the provided information for each affiliation with missing data is correct and amend if deemed necessary. disease identification through segmentation, feature extraction and fusion, feature selection, and classification. The infection regions are extracted using the proposed adaptive and quartile deviation-based segmentation approach and fused resultant binary images by employing the weighted coefficient of correlation (CoC). Then the most appropriate features are selected using a novel framework of entropy and rank-based correlation (EaRbC). Finally, selected features are classified using multi-class support vector machine (MC-SCM). A PlantVillage dataset is utilized for the evaluation of the proposed system to achieving an average segmentation and classification accuracy of 93.74% and 97.7%, respectively. From the set of statistical measure, we sincerely believe that our proposed method outperforms existing method with greater accuracy.

59‐4: A New Method of Side‐wiring Bonding and Patterning for Micro‐LED Display on Glass Substrate

This paper reported a new method of side‐wiring bonding on glass substrate and patterned for large size micro‐LED display. In our experiment, the half hole first fabricated on the side edge of the glass substrate, then the metal was pasted on the side edge, through grounding the metal on the convex edge to form a side metal pattern, The results showed that this scheme can form a conductive side metal pattern for splicing large size micro LED display. This new side‐wiring bonding method can reduce the joint pitch between single glass substrate, and the metal in the hole can be better protected, so as to realize better large size micro LED splicing quality.

Connectedness properties and splittings of groups with isolated flats

In this paper we study CAT(0) groups and their splittings as graphs of groups. For one-ended CAT(0) groups with isolated flats we prove a theorem characterizing exactly when the visual boundary is locally connected. This characterization depends on whether the group has a certain type of splitting over a virtually abelian subgroup. In the locally connected case, we describe the boundary as a tree of metric spaces in the sense of \'Swi\k{a}tkowski. A significant tool used in the proofs of the above results is a general convex splitting theorem for arbitrary CAT(0) groups. If a CAT(0) group splits as a graph of groups with convex edge groups, then the vertex groups are also CAT(0) groups.

Self-bending extrusion molding of distorted channels

Using an integrated profile extrusion and bending forming process with a streamlined extrusion die, a new self-bending extrusion molding technology is proposed with an axis-distorted variable channel. By designing the streamlined extrusion die structure of the distorted central axis, the metal was made to flow non-uniformly in the die cavity, thereby directly extruding a bent profile. The central axis of the streamlined extrusion die is described by a trigonometric function and a Gaussian function. A numerical simulation was applied to analyze the metal flow pattern, equivalent strain, and strain-rate distribution during the self-bending extrusion process. The influences of the extrusion velocity and the addition of a bearing on the self-bending deformation profiles were investigated. During the extrusion process, the streamline at the center of the billet could describe the overall flow of the metal in the die cavity, and the distance between the point on the end face of the die outlet and the center of the die outlet directly determined the degree of extrusion and bending. The greater the distance was, the larger was the degree of bending. The metal strain on the convex edge of the die was greater than that on the concave edge of the die, with the extruded profile always bending toward the concave edge. The strain rate of the metal changed the fastest near the most convex point of the die. As the extrusion velocity increased or more bearings were added, the radius of curvature of the extruded profile increased nonlinearly.

Combustion performance and fuel injection timing adaptability of a lateral swirl combustion system for direct injection diesel engines

To further study the combustion performance and injection timing sensitivity, the lateral swirl combustion system (LSCS) performance was compared against a widely-used TCD combustion system (TCDCS) experimentally in a single-cylinder diesel engine. The experimental results show the LSCS exhibited better combustion performance and lower emissions compared to the TCDCS: the fuel consumption and soot emissions were decreased by 2.5–4.2 g/kW∙h and 0.27–0.73 FSN at different speeds. Further, when the injection timing was retarded from −15 to −8°CA ATDC, the fuel consumption and soot emissions for the LSCS increased by 1.4% and 2%; while for the TCDCS these increases were 2.8% and 17%, respectively. Clearly, the fuel consumption and soot emissions for the LSCS increase relatively slowly. Then, simulation was created to reveal the wall-flow-guided mechanism. For the LSCS, the wall-flow-guided geometry is a vertical convex edge, which is different from a traditional circular ridge: the spay jet almost invariably collides on the convex edge to form the wall-flow-guided and interferential interactions, promoting fuel-air mixing and exerting excellent injection timing adaptability. Therefore, the LSCS exhibits better combustion performance, and appropriately delaying the injection timing can simultaneously obtain relatively better the fuel consumption and soot and NOx emissions.

Efficient approach to designing low OH diffusion in the thermally shaped double-clad fibers

Hydroxyl groups (OH) penetrate the surface of the fiber preforms as a result of preform processing in the oxy-hydrogen flame. Designing double-clad fibers (DCFs) that have a complex noncircular inner-cladding shape with concave and convex edges are possible by shaping their optical preforms thermally with a CO2 laser. Unlike the mechanical technique, the thermal shaping via CO2 laser has paved the way for fabricating DCFs with various inner-cladding geometries that are not limited to the flat edge. However, due to the thermo-physical effects of the CO2 laser on the preform surface, the OH groups are still present in the drawn fibers as they were diffused in the preform while shaping. The OH groups cause attenuation on certain wavelengths that lay rather close to the commonly pumping wavelengths in DCFs. In this work, we have overcome this issue by approaching low OH diffusion in DCFs drawn of thermally shaped optical preforms. This approach was based on treating the preforms with hydrofluoric (HF) acid prior the CO2 laser shaping process in order to remove a thin layer soaked with OH groups. The OH penetration depth was estimated based on the optical attenuation measurement at water peak to be about ~600 µm from preform surface. By etching just 200 µm of the preform surface followed by laser shaping with ablation depth of 300 µm can reduce the attenuation attributed to OH groups by 43%. Surface scattering of the inner-clad shaped DCFs drawn of the etched preforms was shown to be low compared to the DCFs drawn of ground preforms. The measurements were carried out in multimode fibers drawn from pure silica Heraeus F300 rods and coated with low index material.

Septicemia móvel por aeromonada (SMA) em Cyprinus carpio L., 1758 (Actinopterygii: Cyprinidae) no lago Tödürge (Sivas, Turquia)

ABSTRACT In this study, fish’s morphologic and anatomic lesions caused by motile aeromonad septicemia (MAS) depending on environmental stress in carp, Cyprinus carpio population living in Lake Tödürge were identified. Various morphological and anatomical deformations and lesions were observed in the body of approximately 17% (252 fish specimens) of a total of 1488 carp samples. Bacteria are grown from all wipe samples. Bacterial colonies have a gray-white appearance with round, convex and smooth edges. 15-20 cfu colonies were observed in each aerop culture. As a result of analysis of wet wipe samples from infected fish’s skin, gill, kidney and liver, it is determined that the bacteria which causes septicemia is Aeromonas sobria from the Aeromonadaceae family (with 99.2% confidence value). No bacteria were grown in cultures except A. sobria. Some symptoms of the infection are inflammation on different parts of the fish bodies, eruption on skin and scales, dermal necrosis, degeneration at soft rays of the fins, exophthalmos, and purulent liquid accumulation in the abdominal cavity, etc. Infected fish were most commonly encountered in July and August (water temperature above 20ºC), the lowest in October and November (water temperature below 10ºC).

First Report of Pantoea stewartii subsp. stewartii Causing Bacterial Leaf Wilt of Sugarcane in China.

The pathogen of Pantoea stewartii subsp. stewartii (Pss) that is the causal agent of Stewart's bacterial wilt of corn also infects numerous experimental hosts of graminaceous plants (Pepper et al., 1967; Wang et al., 2012). However, little is known about this pathogen naturally infecting sugarcane. In 2017, we observed some sugarcane cultivars showing leaf blade bleaching at the disease initiation stage, which further resulted in development of blight and necrotic lesions (Figure 1-A and -B) in Zhanjiang, Guangdong province of China. To diagnose this putative disease, five symptomatic leaf samples were collected from different sugarcane cultivars. The Pss was found to infect these samples using the nested PCR with Pss-specific outer primers PS1/PS4 and inner primers Ps2r/Ps3r that targeted at the 16S rRNA gene of this pathogen (Wang et al., 2009). The expected 262-bp fragments from positive samples were amplified, cloned, and sequenced (GenBank accession no. MW015795-MW015799). BLASTN analysis revealed that these isolates had more than 99.5% nucleotide identify (222 bp out of 262 bp) with each other and with Pss strains (ATCC 8199 and DC283) as well as P. stewartii subsp. indologenes strains (SR2-12 and LMG 2632) after sequences were trimmed at the 5'- and 3'-terminal of inner primer sequences. In addition, these leaf samples were surface-sterilized with 75% alcohol followed by macerated and chopped in sterile water. Upon plating on solid NA medium at 28 °C for 24-36 h, the bacterial colonies exhibited yellow color with circular, convex, smooth and translucent edges (Figure 1-C). Straight rods and non-encapsulated cells were detected under transmission electron microscopy (Figure 1-D). Moreover, an identical colony termed as PSCN1 was isolated from sugarcane cultivar YZ08-1095 and was further confirmed by the PCR with a universal primer pair 63F (5'-CAGGCCTAACACATGCAAGTC-3') and 1387R (5'-GGGCGGWGTGTACAAGGC-3') that targeted at bacterial 16S rRNA gene (Marchesi et al., 1998). A 1362-bp DNA fragment sequence was obtained from PSCN1 strain and deposited on GenBank library (accession no. MW015767). Sequence analysis showed that PSCN1 shared 99.9-100% nucleotide identity (1315 bp out of 1362 bp) with the two reference strains of Pss (ATCC 8199 and DC283) after sequences were trimmed at the 5'- and 3'-terminal of primer sequences. According to Koch's postulates, pathogenicity test was carried out on YZ08-1095 plants with 3-5 fully developed leaf inoculated with the suspended cells (108 cells/ml) of PSCN1 strain by cutting the one-third of leaves before spraying with a suspension. Control plants were mock-inoculated with serial liquid nutrition agar medium. Two independent experiments were performed for pathogenicity assay and more than 28 plants of YZ08-1095 were used in each treatment. Plants were cultured in a growth chamber at 28 °C and 60% humidity under a 16 h light/8 h dark photoperiod. Leaves inoculated by the PSCN1 initially showed bleached, blight and wilting symptoms on leaf edges at seven days post-inoculation (dpi) (Figure 1-E and -F), which were similar to those symptoms observed in the fields. Control plants remained asymptomatic (Figure 1-G). The average incidence of diseased plant was 51.9% at 21 dpi. The bacteria were subsequently re-isolated from diseased leaves, and yielded colonies were completely identical to the PSCN1. Taken together, our data provides the valuable information for diagnosis and controlling this disease in sugarcane.

Differences in wing shape of captive, critically endangered, migratory Orange-bellied Parrot Neophema chrysogaster relative to wild conspecifics

ABSTRACT Living in a captive environment may compromise phenotypic traits critical to survival in the wild. Captive animals that differ from the ideal wild phenotype may have impaired fitness after release, especially if there is extreme phenotypic selection during some life history stages. Wing shape of migratory birds is crucial to migration efficiency, and changes to wing shape in captivity may severely affect survival after release. We investigate wing shape of migratory Orange-bellied Parrots Neophema chrysogaster in captivity and the wild. The first two flight feathers were shorter in captive birds, and the fifth and sixth feathers were longer than wild conspecifics. These differences altered wing shape, producing a more proximal tip and a more convex trailing edge than the wild phenotype, which likely alters flight performance. This wing shape contravenes expectations from general patterns of wing shape in migratory birds. Wing shape in the captive birds sampled was independent of inbreeding, generations in captivity and ancestry. Captive environments may affect feather development or impose some selective pressure on wing shape. Alternatively, release from intense phenotypic selection during migration may allow parrots with wing shapes poorly adapted to migration to survive and breed in captivity. Altered wing shape may contribute to low observed survival of parrots released to the wild.

Repeated Projectile Impact Tests on Multi-Layered Fibrous Cementitious Composites

This research aims to experimentally evaluate the behaviour of multi-layered fibrous cementitious composites with intermediate Glass Fibre Meshes (GFM) under repeated projectile load. The impact load was subjected through a convex edge projectile needle at a low velocity on cylindrical specimens of three-layered fibrous cementitious composites, which have two different steel fibre distributions. In series A mixtures, a constant steel fibre dosage of 2.5% by volume was used. On the other hand, the fibre dosage of the outer layers was 3.0%; while it was 1.5% in the middle layer of series B mixtures. The number of intermediate GFM was the variable that distinguishes the mixtures of each series. The resistance to projectile impacts was evaluated on the basis of penetration depth, near surface distortion, weight loss, damage ratio and failure pattern. The test results showed that due to the combined effect of steel fibre and GFM, significantly lower weight losses were recorded for series A and B specimens compared with reference specimens. However, the different fibre distributions (series B) led to lower penetration depths and weight losses with less surface distortion compared with the fixed fibre distribution (series A). The reduction in the destroyed front surface area of series A specimens compared with reference specimens ranged from 27.8 to 38.1%; while that of series B specimens ranged from 34.8 to 53.4%. In addition, a simplified analytical model was introduced to predict the ejected composite mass. The model predictions were found to be in good agreement with the experimental masses.

Jet-Like Appearance in Angiography as a Predictive Image Marker for the Occlusion of Intracranial Atherosclerotic Stenosis.

Introduction: Identifying intracranial atherosclerotic stenosis-related occlusion (ICAS-O) in acute ischemic stroke has important clinical significance. Correct identification would help operators devise an optimal recanalization strategy. However, it is often hard to make accurate judgments in emergency situations before thrombectomy. Here, we propose a new image marker for ICAS-O based on the appearance of occluded vessels on baseline digital subtraction angiography.Materials and Methods: We retrospectively reviewed patients with acute ischemic stroke who underwent endovascular therapy from August 2017 to February 2020 at our center. ICAS-O was identified by residual focal stenosis at occluded vessels after successful recanalization. The jet-like appearance was defined as appearance of pencil-tip-like or line-linked contrast filling of the occlusion edge. A non-jet-like appearance was defined as appearance of convex, concave, or flat edge contrast filling. The proportion of jet-like appearance in different occlusion etiologies and occluded vessels was determined. The diagnostic value of jet-like appearance for ICAS-O was assessed.Results: A total of 164 patients diagnosed with ICAS-O were enrolled. Jet-like appearance was detected in 34 (20.7%) patients with younger age (68.0 ± 11.9 years vs. 62.7 ± 10.2, p = 0.019), patients with lower baseline NIHSS scores (16.6 ± 7.1 vs. 12.4 ± 6.5, p = 0.002) and patients with more past stroke or transit ischemic events (31.4 vs. 13.2%, p = 0.011). ICAS-O rate was higher in the jet-like appearance group (82.9 vs. 8.5%, p < 0.001), and rescue methods were more frequently used (74.3 vs. 12.4%, p < 0.001). Jet-like appearance was mostly found at the origin of the middle cerebral artery (MCA) (44.1%), followed by the first segment trunk of MCA (20.6%) and internal carotid artery (ICA) supraclinoid (11.8%). Logistic regression showed that jet-like appearance was independently associated with ICAS-O [OR 180.813, 95% CI (17.966, 1,819.733), p < 0.001]. The sensitivity, specificity, and accuracy values for predicting ICAS-O was 96, 78, and 83%.Conclusion: The jet-like appearance on the angiogram was an image marker for ICAS-O, with relatively high sensitivity and specificity, which could help operators predict underlying intracranial atherosclerotic stenosis in a timely manner and choose the optimal intervention strategy during endovascular therapy.

Energy Integration Method for Calculating k eff and its Application in Design Optimization of Disk Resonators via Convex Edge

Piezoelectric resonators have been extensively used as filters, actuator, and sensors. The effective electromechanical coupling coefficient ( [Formula: see text] is the most useful parameter to evaluate the electromechanical conversion efficiency of piezoelectric resonators. However, even for simple geometry piezoelectric resonators, such as disks, the coupling between different modes makes the resonant characteristics very complex. The coupling causes low electromechanical coupling efficiency of the intended mode. We propose a finite-element-based energy integration method to calculate [Formula: see text] of piezoelectric resonators. This method is more accurate than the conventional resonance-antiresonance method and provides a powerful tool for the design optimization of pure mode resonators. A special case studied here is the fundamental thickness extensional (TE) mode of PZT-8 disks in the aspect ratio range of 2-20. Our results showed that multimode coupling near this mode can be greatly suppressed by modifying the edge surface of the disk to a convex shape. Such an optimized design could enhance [Formula: see text] of the fundamental TE mode by as much as 10%-45% depending on the aspect ratio.

Model test on vertical bearing capacity of X-section concrete pile raft foundation in silica sand

To reveal the bearing capacity of the X-section concrete piles pile raft foundation in silica sand, a series of vertical load tests are carried out. The X-section concrete piles are compared with circular section pile with the same section area. The load-settlement curves, axial force and skin friction, strain on concave and convex edge of the pile, pile-sand stress ratio, distributions of side and tip resistance are presented. The results show that bearing capacity of the X section concrete pile raft foundation is much larger than that of the circular pile raft foundation. Besides, compared with the circular pile, the peak axial force of X-section piles under raft is deeper and smaller while the neutral point of X-section concrete pile is deeper. Moreover, the strain on the concave edge is much larger than that on the convex edge of the pile, and the convex edge has more potential in bearing capacity as the vertical load increases. The X-section pile has higher pile-sand stress ratios and load-sharing between side resistance and tip resistance. Above all, the X-section concrete pile can significantly increase the bearing capacity of pile-raft foundations in silica sand.

Convex Edges in Social Networks

Convex edges are located on convex surfaces of hidden geometry spaces, resulting in shorter geometrical distance than observed. Convex edges reveal the close relationships between two connected nodes and have a key role in many research fields and applications, including social, trust, and protein–protein interaction networks. We first quantitatively define convex edges using hidden geometry space defined by Ricci curvature and show these to be capable of predicting highly interacted edges in social networks. From empirical studies of social networks, we find that convex edges often occur on two connected nodes with similar popularity and allow for frenemy (or versatile node) identification, and that almost all nodes maintain an upper bound of convex edges. These findings present further evidence of the limited attention in an attention economy from a different perspective. Using three well-known synthetic networks, we show that convex edges can reflect the formation of a network from scatter (concave) to aggregation (convex). Taken together, our results show that convex edges are a novel mechanism to investigate social networks from different disciplines and offer insights into many network phenomena.

Verifying the wall-flow-guided assumption of the lateral swirl combustion system in DI diesel engines

A lateral swirl combustion system (LSCS) was designed to promote the spatial spray distribution through the spray wall impingement, and previous studies have established its combustion performance improvement in direct injection (DI) diesel engines. To verify that the improvement in combustion performance is due to the optimal wall-flow-guidance under the assumptive spray impingement position, numerical and experimental tests were conducted under different circumferential injection angles (CIA). The fuel/air mixing and combustion characteristics were computed and analyzed. The endoscopic visualization technique was applied to a single-cylinder diesel engine to record the spray and combustion processes. Based on the two-color method, flame temperature distribution, soot concentration distribution and the corresponding combustion performance were analyzed. Then the variation tendency of combustion performance was further validated under different engine speeds.The numerical and simulation results consistently show that the LSCS chamber and spray jet achieve an optimal match when the spray impingement position is precisely on the convex edge (CIA = 0°). At this position, the LSCS exerts the lowest fuel consumption and soot emission under various engine speeds, because significant lateral swirls form and evenly distribute fuel across all split arcs, promoting the in-cylinder fuel/air mixing and combustion. Therefore, the wall-flow-guided assumption of the LSCS in DI diesel engines is successfully verified in this study.

Investigating Earth Reaction to Pull-Out Process of Frictional Rock Bolts Using Distinct Element Method

The reaction of earth to pull-out process of frictional rock bolts was here modeled by the distinct element method (DEM). Ten frictional bolts were prepared; the expanding shells of five bolts included convex edges and the others had the shells with concave bits. The strength of bolts was measured by applying a standard pull-out test; the results confirmed that the strength of shells with convex edges was remarkably more than the strength of other shells. Furthermore, a two-dimensional DEM model of the test was developed by a particle flow code; the obtained results showed that the reaction of rock particles to the contacts occurring between the convex edges and earth was considerably more than those of the concave bits. In the other words, the convex edges transferred the pull-out force into a large area of the surrounded rock, causing these bolts to have the highest resistance against earth movements.

MICROLITHIC COMPLEX OF LATE GRAVETTIAN OF NORTHERN UKRAINE: ON THE EXAMPLE OF PUSHKARI I AND KLIUSY SITES

This article deals with new results of research microlithic complex of late Gravettian sites Pushkari I and Kliusy (Chernihiv region). The study is based on two large flint collections: Pushkari I, excavation 7 (1998—2018 by V. I. Belyaeva and P. M. Vasyliev) — 36777 units, where 4 % are tools, and 28 % of them are microlithic tools with fragments; Kliusy, excavation 1966 by I. G. Shovkoplyas — 9372 units, where 7.5 % are tools, and 35.5 % of them are microlithic tools with fragments.&#x0D; Microlithic complex from Pushkari I consist of 416 units — backed points (23 %), rectangles (8 %) and their fragments (64 %). Backed points represented by three main types: backed retouched 47 %, semi abrupt retouched 43 %, backed retouched with oblique retouched proximal part 10 %. It’s interesting that more of points with semi abrupt retouched have convex backed side, and backed retouched have a straight side. Rectangles also have divided at backed retouched (42 %), semi abrupt retouched (49 %) and small irregular retouched (9 %). In addition to the retouch they are different in size, semi abrupt retouched microlithics are bigger.&#x0D; Microlithic complex from Kliusy consist of 283 units — backed points (20 %), rectangles (10 %) and their fragments (67 %). Backed points represented by three main types: backed retouched 47 %, semi abrupt retouched 43 %, backed retouched with oblique retouched proximal part 10 %. Also, in complex submitted 4 units (7 %) of shouldered points, probably they are related to different part of the site. Rectangles have divided at backed retouched (28 %), semi abrupt retouched (48 %) and small irregular retouched (24 %).&#x0D; The comparative analysis of the microlithic complexes of Pushkari I and Kliusy sites lots shows, in general, typological and statistical identity. The complexes are represented by products that were used on common principles, but with slightly different shapes. The points of Pushkar I and Kliusy have one retouched long edge, with a puncturing end and a transversely truncated proximal part. At the same time retouching gives the workpiece a straight or convex blunt edge, in Pushkari I dominates — a straight line (68 %), and in Klyusy — a convex (72 %). According to the author, the shape of the blunt edge of the attachment may affect the way it is attached to the tip of the composite tool. Further studies on the study of microlithic complexes, with the involvement of modern science and technology, will provide more information on one of the main spheres of life in primitive society — hunting. Where microlithic products acted as attachments that formed the blades / blades of composite tips from organic materials.

Hydrodynamic performance of multiple co-axial heave plates with different diameters

ABSTRACTHeave plates are structural components of a floating structure whose primary purpose is to increase damping and added mass in heave or pitch direction. If multiple plates are stacked along a common axis, then the relative diameters and spacing in between are important factors affecting the performance. In the present study, hydrodynamic coefficients of single, double and triple disks are experimentally investigated in different arrangements as Uniform, Concave and Convex edge shapes. It is observed that each disk in a multiple arrangement with lower diameter ratio have better hydrodynamic performance compared to the cases with higher diameter ratio when the spacing is small compared to the mean diameter. Some hydrodynamic aspects affecting floating structure design are also discussed in this paper.

Large-scale curvature sensing by directional actin flow drives cellular migration mode switching.

Cell migration over heterogeneous substrates during wound healing or morphogenetic processes leads to shape changes driven by different organizations of the actin cytoskeleton and by functional changes including lamellipodial protrusions and contractile actin cables. Cells distinguish between cell-sized positive and negative curvatures in their physical environment by forming protrusions at positive ones and actin cables at negative ones; however, the cellular mechanisms remain unclear. Here, we report that concave edges promote polarized actin structures with actin flow directed towards the cell edge, in contrast to well-documented retrograde flow at convex edges. Anterograde flow and contractility induce a tension anisotropy gradient. A polarized actin network is formed, accompanied by a local polymerization-depolymerization gradient, together with leading-edge contractile actin cables in the front. These cables extend onto non-adherent regions while still maintaining contact with the substrate through focal adhesions. The contraction and dynamic reorganization of this actin structure allows forward movements enabling cell migration over non-adherent regions on the substrate. These versatile functional structures may help cells sense and navigate their environment by adapting to external geometric and mechanical cues.