Flattened Form Research Articles

Analysis of Agrotechnical Care of Diospyros kakiOrchard Grown in the Sheki-Zagatala Region of the Republic of Azerbaijan

The article published a study of caring for the Diospyros kaki orchard in the Sheki-Zagatala region of the Republic of Azerbaijan. The development of Eastern persimmon depending on the row spacing system was studied and comparatively analyzed. The use of row spacing of green manure plants; when cultivating the row spacing of the eastern persimmon garden, we used legumes + field peas, which has a positive effect on plant growth; an increase in the number of fruits on the tree, the size and weight of the fruits was observed compared to the control. The influence of organic and inorganic fertilizers on the development of Diospyros kaki varieties was studied. The greatest development of 3-year-old trees was observed with the application of N50P20K35+20 tons/ha of inorganic fertilizer (manure). Our research in the conditions of the Sheki-Zagatala region showed that the location of the root system of Diospyros kaki on the surface requires frequent watering with low rates. During the growing season, good results were achieved by 5-6 times irrigation with a water norm of 350-400 m3 each time, since brown mountain-forest soil type predominates in our experimental plots. Among tree pruning methods tested, the vertical flattened form was found to be superior in both efficiency and overall yield. The influence of methods of pruning the crown of Diospyros kakion the yield of the 1st tree in all varieties increased. The Tamopan variety has the best results. Pruning trees using the free-growing method amounted to 154.0 kg, and the vertically flattened method amounted to 174.0 kg, which means an increase in yield from 1 tree by 11.5%. Our research has once again shown that, depending on the soil and climatic conditions of the region, it is necessary to carry out timely and comprehensive agrotechnical care of the orchard, as this will allow obtaining a high-quality harvest and a healthy garden.

Film Thickness Decay and Wear Behavior of Grease-Lubricated Point Contact under Cyclic Variable Loads

For wind turbine applications, there is a cyclic load-varying process between rolling elements and raceways in pitch bearings. This kind of motion can also lead to radial fretting. However, this is seldom addressed under grease-lubricated conditions in the literature. In this study, grease-lubricated point contact problems have been investigated experimentally under cyclic load-varying conditions. The findings revealed that as the load-varying range diminishes, the variation in grease film distribution becomes more subtle and the rate of discharge of thickener fiber clusters in the stick zone decelerates. This is due to the fact that the rate of change in the Hertz contact radius is reduced and the migration of grease is weakened during the unloading process. Due to the large apparent viscosity of grease with a high soap content, entrapped grease is not easily discharged during loading, and the thickness of the film in the stick zone progressively increases as the soap content of the grease is augmented. This also causes the variable load zone to wear out more easily. As the grease is subjected to repeated loading and unloading, there is a gradual reduction in film thickness, and larger thickener fiber clusters tear, resulting in a flattened form and shear thinning. Grease containing sulphur–phosphorus additives demonstrates a superior effect on reducing fretting wear within the large variable load range but generally proves effective for smaller load-varying ranges. This study may offer insights into the degradation of grease under variable load motion and methods to prevent radial fretting wear.

Queer Data: Ronald Firbank and the Information Economy

Abstract: What can a study of "data" contribute to our understanding of early twentieth-century literary culture and how can data aesthetics help to explicate the seemingly obtuse style of writer Ronald Firbank? This article addresses both of these questions by considering the forms and function of data in Firbank's writings. It argues that Firbank's characteristic camp and elusive style can be understood as an examination of the information economy in which he was living, an economy that traded in flattened forms and decontextualized data.

A new species of saxicolous Lepidophyma (Squamata, Xantusiidae) from Tamaulipas, Mexico

We describe a new saxicolous species of Lepidophyma from the Sierra Madre Oriental, in the state of Tamaulipas, Mexico and provide morphological and molecular data to support the novelty of this species. The new species is most closely related to members of the L. sylvaticum group; however; it is a flattened form specialised for a saxicolous lifestyle and it can be distinguished from all other members by a combination of meristic characters. Genetic analysis suggests that several populations of L. sylvaticum might represent additional novel taxa, while the validity of L. micropholis is questioned. We discuss conservation priorities of the new species.

Separation of wavy and polylobate forms of phytoliths of the “crenate” morphotype in Pooideae Benth. species of the south of Western Siberia on the basis of phylogenetic data

The article deals with the problem of nomenclature and classification of phytoliths. The division of the “crenate” morphotype (ICPN 2.0) into two forms – polylobate and wavy – is substantiated using Pooideae grasses from the south of Western Siberia. An analysis of the literature data confirms the heterogeneity of this morphotype and various interpretations of its variations. The polylobate group includes phytoliths high in lateral projection with distinct lobes, and the wavy group includes flattened forms with a wavy edge. The article details the formation of these two morphotypes in 52 grass species belonging to 25 genera. The main content of the study is an analysis of the occurrence of forms in various tribes and subtribes according to modern information on the phylogeny of cereals. The differences in the formation of these morphotypes at the sectional and subgeneric levels are considered using as examples three genera. The detailed analysis shows that wavy plates are most typical for the subtribe Aveninae(Poeae), polylobed particles are typical for the subtribe Agrostidinae (Poeae) and the tribe Meliceae. For some taxa, for example, the tribe Stipeae, ambiguous data have been obtained that are inconsistent with information from other territories, which indicates the need for further research on this problem. The analysis of occurrence of forms at the intrageneric level shows that in the genera Poa and Festuca there are differences between individual subgenera and sections, while for the genus Calamagrostis there are no such differences. The results obtained point to the prospect of using phylogenetic information in the classification of phytoliths and the need for a more complete study of large genera of grasses in terms of phytolith composition (Festuca, Calamagrostis, Poa, Stipa, etc.).

Identification and localization of Pt species in Pt-NaA zeolite catalysts prepared by direct synthesis

Several characterization techniques were employed to elucidate the Pt species present in the structure of Pt-NaA catalysts. Three types of Pt particles were identified: nanoparticles located at the surface of the crystals (with a higher size and flattened form), 1–2 nm particles inside the structure, and sub-nanometric particles, lower than 1 nm, confined in the pores. The low PtPt coordination number (EXAFS) is compatible with both flattened dihedral-like morphology, as well as the presence of sub-nanometric particles. The Pt0.6_NaA catalyst exhibited higher activity (in the WGS) than the other catalysts, which could be related to the presence of small particles.

Deep structure of the Salair fold-nappe terrane (NW CAOB) according to magnetotelluric sounding

The Salair fold-nappe terrane (a.k.a. Salair orogen, Salair) is the northwestern part of the Altai-Sayan folded area of the Central Asian Orogenic Belt. It is composed of Cambrian – Early Ordovician volcanic rocks and island-arc sedimentary deposits. In plan, Salair is a horseshoe-shaped structure with the northeast-facing convex side, which is formed by the outcrops of the Early Paleozoic folded basement. Its inner part is the Khmelev basin composed of Upper Devonian – Lower Carboniferous sandstones and siltstones. The Early Paleozoic volcanic rocks and sediments of Salair are overthrusted onto the Devonian-Permian sediments of the Kuznetsk basin. The Paleozoic thrusts, that were reactivated at the neotectonic stage, are observed in the modern relief as tectonic steps. Our study of the Salair deep structure was based on the data from two profiles of magnetotelluric sounding. These 175-km and 125-km long profiles go across the strike of the Salair structure and the western part of the Kuznetsk basin. Profile 1 detects a subhorizontal zone of increased conductivity (100–500 Ohm·m) at the depths of 8–15 km. At the eastern part of Profile 1, this zone gently continues upward, towards a shallow conducting zone that corresponds to the sediments of the Kuznetsk basin. Two high-resistance bodies (1000–7000 Ohm⋅m) are detected at the depths of 0–6 km in the middle of the section. They are separated by a subvertical conducting zone corresponding to the Kinterep thrust. The main features are the subhorizontal positions and the flattened forms of crustal conductivity anomalies. At the central part of Profile 2, there is a high-resistance block (above 150000 Ohm⋅m) over the entire depth range of the section, from the surface to the depths of about 20 km. In the eastern part of Profile 2, a shallow zone of increased conductivity corresponds to the sediments of the Kuznetsk basin. The subhorizontal mid-crust layer of increased conductivity, which is detected in the Salair crust, is typical of intracontinental orogens. The distribution pattern of electrical conductivity anomalies confirms the Salair thrust onto the Kuznetsk basin. The northern part of the Khmelev basin is characterized by high resistivity, which can be explained by abundant covered Late Permian granite massifs in that part of the Khmelev basin. The Kinterep thrust located in the northeastern part of the Khmelev basin is manifested in the deep geoelectric crust structure as a conducting zone, which can be considered as an evidence of the activity of this fault.

Horse Whip Pommels With a Special Protrusion of the XI—XIII Centuries (Based on the Materials of the National Museum of History of Ukraine)

To bridge a riding war horse and subordinate it to the will of the rider is possible through the usage of harness and other special equipment, which were fixed on an animal or operated by a person. In addition, a whip was used to execute the orders of the rider more effectively. The whip occured in the complex of weapons of the Ancient Rus warrior from a nomadic environment, where it simultaneously acted as a cult attribute and a kind of amulet. The structure of the whip provided the following components: a whip woven made of leather straps, a whip-handle, which ended with a knob at the pommel. Nowadays, there are different whip pommels according to their shape, material of manufacture and construction. The parts of the handle are divided into groups due to the material of manufacture (bone/horn, metal), into types according to the body shape, and into ornamental schemes if possible. All of them are connected by the presence of a typical protrusion, which prevented the whip from falling out of the rider’s hand and, in some cases, acquired a certain visual similarity to the head of a bird, or had specific zoomorphic (ornithological) features. Four types are distinguished for bone knobs (group I): spherical flattened; barrel-shaped rounded and with elongated proportions; with zoomorphic features; attached to the heads of the natural curves of the horny outgrowth. Metal knobs are of five types (group II): spherical; barrel-shaped elongated; zoomorphic; with cut corners; star-shaped. In the Eastern European region, finds of whip pommels with somewhat flattened forms and small beak-like outgrowths begin to be recorded from the X c. and all items are exclusively made of bone. The round, spherical and barrel-shaped knobs with elongated projections appear in the second half of the XI c. and continue to exist in the next two centuries. Zoomorphic knobs in the shape of a bird’s head of small proportions existed for a relatively short time — XI — first half of the XII c., and items on an elongated socket – from the XII — first half of the XIII c. The knobs with cut corners are dated more widely, within the XII—XIII/XIV c. The National Museum of the History of Ukraine contains eight items representing the corresponding pommels or their parts. Two finds are of unknown origin, and six are identified and come from Ancient Rus settlement structures of the XI—XIII c. from the territory of the Ros River region: Nabutiv, Kononcha, Sharky, Kniazha Hora.

Effect of ozonation on resistance of ovine and human erythrocytes to hypothermic storage

Long-term hypothermic storage of animal blood can lead to the loss of its quality and can cause complications in recipient animals after transfusion, so the search for new methods of increasing the preservation of erythrocytes after hypothermic storage continues. The article presents the data of the ozonation effect on the preservation rate of ovine and human erythrocytes during hypothermic storage with Alsever’s solution and mannitol medium. Hemolysis, osmotic fragility and distribution density of ovine and human erythrocytes by the sphericity index were determined at different stages of hypothermic storage. The ovine erythrocytes in the control had a lower osmotic resistance compared to human erythrocytes; however, their osmotic fragility did not change significantly after hypothermic storage for 8 weeks, and for human erythrocytes, it significantly increased. Storage of ovine and human erythrocytes longer than 8 weeks led to a sharp hemolysis, while the level of hemolysis of ovine erythrocytes was lower than that of human erythrocytes. Preservation of ozonated erythrocytes is higher than non-ozonated ones during prolonged hypothermic storage. The effect of ozonation on the preservation rate of red blood cells depended on the composition of the preservation media. Hypothermal storage of human erythrocytes in Alsever’s solution for up to 8 weeks led to a shift in the density of distribution according to the sphericity index towards spheroidization of cells; in a medium with mannitol, the number of flattened cell forms increased. After 8 weeks of hypothermic storage of ovine erythrocytes, most of the cells had high sphericity indices. Pretreatment of human and sheep erythrocytes with ozone allows the distribution of cells to be kept closer to the control during long-term storage, which is especially pronounced in mannitol medium. Ovine erythrocytes retained the ability to form rosettes with human T-lymphocytes after hypothermic storage for up to 12 weeks. Thus, ozone pretreatment and the use of mannitol as part of hypothermic storage medium could be an approach to improve the quality of preserved ovine erythrocytes.

Potential evolutionary trade‐off between feeding and stability in Cambrian cinctan echinoderms

AbstractReconstructing the function and behaviour of extinct groups of echinoderms is problematic because there are no modern analogues for their aberrant body plans. Cinctans, an enigmatic group of Cambrian echinoderms, exemplify this problem: their asymmetrical body plan differentiates them from all living species. Here, we used computational fluid dynamics to analyse the functional performance of cinctans without assuming an extant comparative model. Three‐dimensional models of six species from across cinctan phylogeny were used in computer simulations of water flow. The results demonstrate that cinctans with strongly flattened bodies produced much less drag than species characterized by dorsal protuberances or swellings, suggesting the former were more stable on the seafloor. However, unlike the flattened forms, cinctans with high‐relief bodies were able to passively direct flow towards the mouth and associated food grooves, indicating that they were capable of more efficient feeding on particles suspended in the water. This study provides evidence of a previously unknown evolutionary trade‐off between feeding and stability in Cambrian cinctan echinoderms.

СТЕПЕНЬ ПОДКИСЛЕНИЯ СЫРОГО ФУРАЖНОГО ЗЕРНА ЯЧМЕНЯ В ЗАВИСИМОСТИ ОТ УСЛОВИЙ КОНСЕРВИРОВАНИЯ

Fodder grain plays a priority role in ensuring high productivity of farm animals and poultry, revealing their genetic potential. Therefore, it is necessary to use the most advanced methods of grain preservation for the most complete preservation of the original feeding power. Such methods in recent years include the technology of sealed storage of raw fodder grain harvested before the complete maturation phase. Various biological and chemical additives are used to improve the preservation results. The use of such additives (due to the specific features of preserved raw materials) is obligatory. The authors conducted comparative tests of certain types of additives for processing raw fodder grains in the whole and flattened forms to determine the effect of different degree of compaction on the effectiveness of their preserving action. They made an experiment,and the quality of fermentation was determined using generally accepted methods. The raw grain isolated from air access is protected from spoilage due to acidification, so the effectiveness of using preservative additives was primarily determined by the effect on this indicator. The whole grain was put into storage with a higher moisture content (35%) than the flattened one (about 25%),which ensured its significantly better acidification regardless of the degree of compaction. A denser grain storage pattern provided better grain acidification regardless of grain moisture. From tested preparations, the flattened grain was better acidified by powdered sulphur at the medium degree of compaction for storage; the whole grain was better acidified by Biosil NN at the maximum degree of compaction. On average the preparations used in the experiment were arranged in the following sequence (as their influence on the degree of grain acidification weakened): powdered sulphur → biopreparations Biosil NN → chemical preservative Promir.

Insight into tidal disturbance on colonization surveys for marine bioassessment using periphytic ciliates based on biological trait analysis

Abstract To understand tidal disturbance on the colonization dynamics in community functioning of the ciliates in marine ecosystems, a 1-month survey was conducted using the conventional slide system (CS) and the polyurethane foam enveloped slide system (PFES) in Korean coastal waters. The results showed considerable differences were detected in community functioning parameters between the two systems. The vagile, flattened forms feeding on periphytic microalgae showed a higher community-weighted mean (CWM) value, and the solitary-colonial pattern represented a more stable temporal variability during the colonization in the PFES system than the CS system. The temporal shift in community functioning of the ciliates showed different ways in both systems. The functional diversity measures generally levelled off at more stable values in the communities with ages of 13–15 days in the PFES system than the CS system. These results imply that the PFES system may be a workable method for bioassessment in marine ecosystems.

Morphological features of livers of sexual mature dogs

The article describes the features of the macroscopic and microscopic structure of the liver of mature clinically healthy dogs for the use of anatomical, histological and morphometric methods of research. According to the results of organometallic and cytometric studies, the absolute and relative body mass, the volume of hepatocytes, their nuclei and the nuclear-cytoplasmic ratio were determined. Thus, the absolute weight of the liver in the mature dogs is variable and to a certain extent depends on the blood flow to the organ and is 427.4 ± 21.92 g, the relative weight – 2.69 ± 0.1%. Liver of mature dogs is a compact body of flattened form with sharp lower and lateral edges, with deep cuts, dark red color. The histoarhitectonics of the liver of dogs are constructed with connective tissue and parenchyma. The stroma of the organ is formed by a capsule, on top of which is serous membrane. In the area of the gates of the liver, the connective tissue of the capsule penetrates into the middle of the organ, branching and dividing it into lobules. Then it is formed by the hepatic plates by the intraosseous sinusoid capillaries. Liver plates are specific endpoint of the secretory unit of the liver. It has been found that in the microscopic structure of the liver of the dogs, the interstitial connective tissue is poorly developed, therefore the boundaries between the liver lobules are not sufficient. The liver plates behind the microscopic structure have a radial direction from the center to the periphery. The direction closer to the periphery of the particles is less noticeable, since hepatocytes are located in two rows, between which the sinusoidal space clearly appears. Hepatocytes had an irregular, multifaceted form. Their nuclei, which were mainly in the center of the cell, had little clarity of contours of carriel and well perceived color. During microscopic examination of the liver, it is swollen that hepatocytes of the central and intermediate zones are better perceived by color than the cytoplasm of the cells of the peripheral zone of the liver. According to the analysis of our cytomorphometric studies, hepatocytes of dogs have different sizes, which vary in wide range: from small to large. Whereas the average volume of hepatocytes in mature dogs is 964.72 ± 56.003 μm³; the average volume of their nuclei is 105.13 ± 2.02 microns. The nuclear-cytoplasmic ratio of hepatocytes in dogs of this group is 0.128 ± 0.122.

Topographic gradients and lode gold sourcing recorded by placer gold morphology, geochemistry, and mineral inclusions in the east fork San Gabriel River, California, U.S.A

Topography plays a major role in the morphology, geochemistry, and mineral inclusion profiles of placer gold from the East Fork of the San Gabriel River. These trends are consistent with a significant change in topographic gradient over a short distance, and coincident with the break in slope along the range-front of the San Gabriel Mountains. Placer gold from above this topographic transition is more rounded and 3-dimensional, with elevated silver in the alloy of the native gold, little evidence of gold enrichment rims, and abundant inclusions of brittle and reactive minerals. Below the topographic transition, placer gold assumes a distinctly flattened form, with lower silver alloy content, thin gold enrichment rims, and rare inclusions of relatively inert minerals. This relationship is observed for placer gold shed from two inferred lode sources within the river catchment, with placer gold from each of these sources being traceable as a unique population over at least 8 km of the river. Significantly, these placer gold properties are distinctive enough to fingerprint gold from specific portions of the placer deposit. These identifying characteristics, with virtually identical morphology and chemical trends, are observed in the large nuggets of the Mel Fisher collection of purported San Gabriel gold. These similarities appear to confirm the provenance of the collection, including identification of the specific locations where each nugget originated.

Dual Precisionism

“Precisionism” is a notoriously slippery word. This short article asks readers to think critically and expansively about the term. The essay suggests that Precisionism might be defined most aptly in a dual sense, as describing a set of works that favor mechanical subjects and bear stylistic affinities with products crafted by machines. Works by George Ault and Charles Sheeler, for example, suggest that the term characterizes not only hard-edged depictions of factories, machines, and machine parts, but also works that appear as though they could have been produced or improved by such apparatuses. This is especially the case with etchings by Armin Landeck and lithographs by Sheeler and Louis Lozowick. In these works, the printing press itself figures as one such machine facilitating the production of the clean lines, flattened forms, emphatic contours, and localized colors that the Precisionist artists sought.

Leadership: Past, Present, and Future: An Evolution of an Idea

Defining a leader and the qualities that demonstrate leadership have evolved over the past centuries. Researchers have explored leadership traits using various methodologies since the concept of the leader and leadership has arisen in the lexicon. However, a consistent methodology or even consensus of the nature of effective leadership has been the subject of great debate. Understanding the ideals of leadership that help identify great leaders requires a reexamination of the historical evolution of leadership theories and principles. The early ideas of leadership were born of an age of expansion and industrial revolution that identified a leader as that one, great individual. Through this tour of history, the theories surrounding leaders and leadership have evolved and changed with each era. Trait theory and behavioral models have given way to ideals such as authentic leadership and environmental influenced leadership. More modern theories invert the traditional paradigm of vertical leadership to a flattened form of dynamic leadership where leaders are interchangeable dependent upon the task. While the intricacies of each theory cannot be completely and exhaustively examined in this text, the review and evolution of leadership principals is important in providing a framework to a better understanding as to the evolution of leadership theory from the early to modern age.

Morphoanatomical Adaptations to Environmental Conditions in Seeds of Some Species of the Genus Iris L. (Iridaceae, Asparagales) Growing in the Saratov Region

Morphoanatomical features important for plant adaptation to ecological conditions have been described for seeds of seven Iris species growing in the Saratov region. Such features are the most indicative for seeds of two species, I. halophila Pall. and I. pseudacorus L. The strategy of I. halophila seeds represents development of adaptations intended to protect seed contents against penetration of saline solutions. These adaptations include the presence of a waterproof and salt-proof coating film protecting seed contents against saline solutions, the maximum level of a seed cover lignification as compared with the seeds of other species studied, and a smooth ultrasculpture of a seed cover preventing salt deposition on its surface. The strategy of I. pseudacorus seeds includes formation of seeds capable of surviving in an aquatic environment for a long time without any loss of viability. The corresponding adaptations are the following: a flattened discoid form of seeds facilitating their floating in water; the maximum thickness of a seed cover compared to other species studied; weak lignification of the seed cover, especially mesotesta; and the presence of an air cavity in the chalazal part of a seed, which reduces its specific gravity and presumably provides an embryo with oxygen when seeds float in water. Seeds of five other iris species (I. aphylla L., I. pineticola Klokov, I. pumila L., I. sibirica L., and I. tenuifolia Pall.) have identical adaptations to moderate conditions of a terrestrial environment.

Effect of disorder on the spatial structure of damage in slowly compressed porous rocks.

Faults and damage zone properties control a range of important phenomena, from the hydraulic properties of underground reservoirs to the physics of earthquakes on a larger scale. Here, we investigate the effect of disorder of porous rocks on the spatial structure of damage emerging under compression. Model rock samples are numerically generated by sedimenting particles where the amount of disorder is controlled by the particle size distribution. To obtain damage bands with a sufficiently large length along axis, we performed simulations of 'Brazilian'-type compression tests of cylindrical samples. As failure is approached, damage localization leads to the formation of two conjugate shear bands. The orientation angle of bands to the loading direction increases with disorder, implying a decrease in the internal coefficient of friction. The width of the damage band scales as a power law of the degree of disorder. Inside the damage band, the sample is crushed into a large number of pieces with a power law mass distribution. The shape of fragments undergoes a crossover at a disorder-dependent size from the isotropy of small pieces to the anisotropic flattened form of the large ones. The results provide important constraints in understanding the role of disorder in geological fractures.This article is part of the theme issue 'Statistical physics of fracture and earthquakes'.

Crystal structure of (-)-(R,E)-3-(1,3-benzodioxol-5-yl)-5-[(4S,5R)-5-hy-droxy-methyl-2,2-dimethyl-1,3-dioxolan-4-yl]-N,N-di-methyl-pent-4-enamide.

In the title compound, C20H27NO6, the amide moiety is essentially planar, with a maximum deviation of 0.073 (3) Å, and one of the N-methyl groups shows rotational disorder. The five-membered 1,3-dioxolane ring adopts an envelope form, with the C atom bonded to the olefin side chain as the flap, which deviates from the mean plane through the other four atoms by 0.564 (7) Å. The 1,3-dioxole ring fused to the benzene ring adopts a flattened envelope form, with the C atom between the two O atoms as the flap, which deviates from the mean plane through the other four atoms by 0.215 (7) Å. The C-C=C-C olefin moiety is essentially planar and makes a dihedral angle of 87.1 (3)° with the benzene ring. An intra-molecular O-H⋯O hydrogen bond supports the mol-ecular conformation, enclosing an S(11) graph-set motif. In the crystal, inter-molecular C-H⋯O hydrogen bonding links the mol-ecules into a tape running along the b axis. Furthermore, other weak C-H⋯O hydrogen bonds and a C-H⋯π inter-action connect the tapes into a sheet structure parallel to (100).

Quantitative Analysis of the Urban Factors Limiting Central District Plane Form Expansion: Twenty-one Case Studies of Asian Megacities′ Central Districts

Based on threshold analysis theory, spatial limiting factors such as mountains, rivers, and roads not only affect the way in which cities spread out, but also play a vital role in shaping the flattened forms of their central districts. This study, based on field investigations of 21 central districts in 13 Asian megacities, seeks out limiting factors that determine the boundaries of urban central districts by quantifying the spatial boundary and distance of the limiting factors. The results suggest a strong correlation between the spatial limiting factors and the urban central district′s form. The limiting elements constrain the size of buildings and population density based on floor area ratio, building density, and development boundaries. Reduction in population and the inconvenience of traffic have decreased urban vitality, leading to delays in the extension of cites′ central districts. It is necessary to fully consider the role of the city′s internal limiting elements in order to reasonably plan the construction of an urban central district.