Adjoining Boundary Research Articles

A cochlear progenitor pool influences patterning of the mammalian sensory epithelium via MYBL2.

During embryonic development, Wnt signaling influences both proliferation and sensory formation in the cochlea. How this dual nature of Wnt signaling is coordinated is unknown. In this study, we define a novel role for a Wnt-regulated gene, Mybl2, which was already known to be important for proliferation, in determining the size and patterning of the sensory epithelium in the murine cochlea. Using a quantitative spatial analysis approach and analyzing Mybl2 loss-of-function, we show that Mybl2 promoted proliferation in the inner sulcus domain but limited the size of the sensory domain by influencing their adjoining boundary position via Jag1 regulation during development. Mybl2 loss-of-function simultaneously decreased proliferation in the inner sulcus and increased the size of the sensory domain, resulting in a wider sensory epithelium with ectopic inner hair cell formation during late embryonic stages. These data suggest that progenitor cells in the inner sulcus determine boundary formation and pattern the sensory epithelium via MYBL2.

Thermoelectric properties of Zn-Sb compound semiconductor

The article discusses the results obtained in the study of the thermoelectric properties of the semiconducting Zn-Sb polycrystalline structure obtained by powder technology. Studies show that thermal processing stages and temperature changes significantly affect its thermoelectric properties. At the initial stages of heat treatment, with an increase in temperature, the Seebeck coefficient (α), thermal conductivity (λ) and thermoelectric index (ZT) first decrease, then increase, and decrease again with an increase in temperature. From the fourth stage of heat treatment, all parameters increase with temperature. The research results were explained on the basis of the formation of intergranular boundary areas and its physical properties. The first stage of thermal treatment is the initial stage of ZnSb particle fusion, and the supplied thermal energy Q is not enough for ZnSb particle fusion. In the next stage of heat treatment, the atoms of the crystal lattice, which consists of a broken bond or defect between the pressed particles, are forced together or condensed. As the temperature increases, the phases of the crystal lattice atoms change and their reactivity increases. This leads to the formation of a ZnSb semiconductor with a polycrystalline structure. As the temperature increases, the localized traps with Ein energy level are ionized and electron-hole pairs are formed in the two adjoining boundary areas. Charges created in area A move to area V, which has a relatively low temperature, along the Ein energy levels. As a result, the total λ increases at the same time as the thermal conductivity of these two adjacent areas.

Boundary constrained voxel segmentation for 3D point clouds using local geometric differences

In 3D point cloud processing, the spatial continuity of points is convenient for segmenting point clouds obtained by 3D laser scanners, RGB-D cameras and LiDAR (light detection and ranging) systems in general. In real life, the surface features of both objects and structures give meaningful information enabling them to be identified and distinguished. Segmenting the points by using their local plane directions (normals), which are estimated by point neighborhoods, is a method that has been widely used in the literature. The angle difference between two nearby local normals allows for measurement of the continuity between the two planes. In real life, the surfaces of objects and structures are not simply planes. Surfaces can also be found in other forms, such as cylinders, smooth transitions and spheres. The proposed voxel-based method developed in this paper solves this problem by inspecting only the local curvatures with a new merging criteria and using a non-sequential region growing approach. The general prominent feature of the proposed method is that it mutually one-to-one pairs all of the adjoining boundary voxels between two adjacent segments to examine the curvatures of all of the pairwise connections. The proposed method uses only one parameter, except for the parameter of unit point group (voxel size), and it does not use a mid-level over-segmentation process, such as supervoxelization. The method checks the local surface curvatures using unit normals, which are close to the boundary between two growing adjacent segments. Another contribution of this paper is that some effective solutions are introduced for the noise units that do not have surface features. The method has been applied to one indoor and four outdoor datasets, and the visual and quantitative segmentation results have been presented. As quantitative measurements, the accuracy (based on the number of true segmented points over all points) and F1 score (based on the means of precision and recall values of the reference segments) are used. The results from testing over five datasets show that, according to both measurement techniques, the proposed method is the fastest and achieves the best mean scores among the methods tested.

Solving Square Jigsaw Puzzle by Hierarchical Loop Constraints.

We present a novel computational puzzle solver for square-piece image jigsaw puzzles with no prior information such as piece orientation or anchor pieces. By "piece" we mean a square $d$d x $d$d block of pixels, where we investigate pieces as small as 7 × 7 pixels. To reconstruct such challenging puzzles, we propose to find maximum geometric consensus between pieces, specifically hierarchical piece loops. The proposed algorithm seeks out loops of four pieces and aggregates the smaller loops into higher order "loops of loops" in a bottom-up fashion. In contrast to previous puzzle solvers which aim to maximize compatibility measures between all pairs of pieces and thus depend heavily on the pairwise compatibility measures used, our approach reduces the dependency on the pairwise compatibility measures which become increasingly uninformative for small scales and instead exploits geometric agreement among pieces. Our contribution also includes an improved pairwise compatibility measure which exploits directional derivative information along adjoining boundaries of the pieces. We verify the proposed algorithm as well as its individual components with mathematical analysis and reconstruction experiments.

A method for solving an exterior three-dimensional boundary value problem for the Laplace equation

We develop and experimentally study the algorithms for solving three-dimensionalmixed boundary value problems for the Laplace equation in unbounded domains. These algorithms are based on the combined use of the finite elementmethod and an integral representation of the solution in a homogeneous space. The proposed approach consists in the use of the Schwarz alternating method with consecutive solution of the interior and exterior boundary value problems in the intersecting subdomains on whose adjoining boundaries the iterated interface conditions are imposed. The convergence of the iterative method is proved. The convergence rate of the iterative process is studied analytically in the case when the subdomains are spherical layers with the known exact representations of all consecutive approximations. In this model case, the influence of the algorithm parameters on the method efficiency is analyzed. The approach under study is implemented for solving a problem with a sophisticated configuration of boundaries while using a high precision finite elementmethod to solve the interior boundary value problems. The convergence rate of the iterations and the achieved accuracy of the computations are illustrated with some numerical experiments.

Seismic anisotropy beneath the Juan de Fuca plate system: Evidence for heterogeneous mantle flow

Here we use SKS shear wave splitting observations from ocean-bottom seismometer data to infer patterns of mantle deformation beneath the Juan de Fuca plate and its adjoining boundaries. Our results indicate that the asthenosphere beneath the Juan de Fuca plate responds largely to absolute plate motion with an anisotropic layer developing rapidly near the ridge and persisting into the subduction zone. Geographically restricted deviations from this pattern indicate the presence of secondary processes. At discrete plate boundaries, such as the Blanco transform fault, seismic anisotropy is attributed to relative plate motion within a narrow zone (<50 km). Beneath the deforming southern Gorda plate region—a diffuse plate boundary—splitting observations similarly suggest deformation dominated by relative motion between the rigid Juan de Fuca and Pacific plates but distributed over a broad zone (∼200 km). Our results are inconsistent with toroidal flow around the southern edge of the subducting slab due to rollback, as suggested by onshore studies. Instead, reorganization of upper mantle flow associated with plate fragmentation seems to dominate the anisotropic signature of southern Cascadia.

Phytoplankton motility and the competition for nutrients in the thermocline

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 347:21-38 (2007) - DOI: https://doi.org/10.3354/meps06999 Phytoplankton motility and the competition for nutrients in the thermocline Oliver N. Ross1,*, Jonathan Sharples2 1Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK 2Proudman Oceanographic Laboratory, Joseph Proudman Building, 6 Brownlow Street, University of Liverpool, Liverpool L3 5DA, UK *Email: onross@essex.ac.uk ABSTRACT: Diatoms and dinoflagellates are 2 important groups of phytoplankton that co-exist in the competition for light and nutrients. Following the diatom-dominated spring bloom, the shelf sea subsurface chlorophyll maximum (SCM) is often dominated by motile species of phytoplankton, in particular dinoflagellates and sometimes coccolithophores. Turbulence in shelf seas, driven by surface winds and by tidal currents, is likely to easily counteract the typically weak swimming capabilities of phytoplankton. The thermocline marks a low turbulence region, separating the nutrient-depleted surface (wind-mixed) layer and the nutrient-replete bottom (tidally-mixed) layer, and so would seem to be an ideal environment for employing a strategy of vertical migration. However, the positioning within the thermocline is crucial, as turbulence in the adjoining boundary layers removes cells that stray too close to the edges of the thermocline and mixes them into resource-limited layers of the water column. We combined a Lagrangian random walk model, a k-ε turbulence scheme and a simple photosynthesis model to track individual phytoplankton cells in a tidally-mixed, stratified water column (e.g. a summer, temperate shelf sea). By allowing motile and non-motile species to compete, we found that an ability to use motility to balance resource requirements can offset modest physiological disadvantages compared to the non-motile phytoplankton, leading to either co-existence or even dominance of the motile species. However, more severe physiological disadvantages (e.g. combinations of growth rate, nutrient uptake capabilities, and/or respiration) cannot be compensated for by motility alone, and further adaptations (such as mixotrophy) would be required. We also show that the SCM can be a place for significant new production (values of 1 g C m–2 d–1 and f-ratios of over 0.5 are possible), which stresses its potential importance as a source of food to the pelagic throughout summer. KEY WORDS: Phytoplankton species competition · Motility · Tidal mixing · Shelf sea thermocline · Carbon export · Nitrogen flux · f-ratio · Turbulence modelling · Lagrangian modelling Full text in pdf format PreviousNextCite this article as: Ross ON, Sharples J (2007) Phytoplankton motility and the competition for nutrients in the thermocline. Mar Ecol Prog Ser 347:21-38. https://doi.org/10.3354/meps06999 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 347. Online publication date: October 11, 2007 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2007 Inter-Research.

Computer Modeling of Extrusion by the Rigid-Plastic Hybrid Element Method

In this paper, a rigid-plastic hybrid element method is formulated, which is a mixed approach of the rigid-plastic domain-BEM and the rigid-plastic FEM based on the theory of slightly compressible plasticity. Since compatibilities of velocity and velocity's derivative between adjoining boundary elements and finite elements can be met, the velocity and the derivative of velocity can be calculated with the same precision for this hybrid element method. While, the compatibility of the velocity's derivative cannot be met for the rigid-plastic FEMs.

Kinematics of connected grain boundaries in 2D

The motion of connected boundary systems was investigated in Al and Zn tricrystals. It was found that triple junctions can exert a drag force on the adjoining boundaries owing to a lower mobility. This drag manifests itself by a deviation of the dihedral angles at the triple junction from the equilibrium angles due to grain boundary surface tensions. The strength of triple junction drag can be expressed in terms of a criterion Λ = (m tj . a/m b ), where m tj is the triple junction mobility, m b the boundary mobility, and a is the grain size. Therefore, the effect should be particularly pronounced in fine-grained and nanocrystalline materials. It is shown that the von Neumann-Mullins relation of 2D grain growth is modified by triple junction drag such that there is no unique relationship between growth rate and the number of sides anymore. For very small Λ, the triple junctions control grain structure evolution during grain growth, which leads to polyhedral grain shapes with flat boundaries. The theoretical concept is supported by computer simulations of grain growth and in-situ annealing experiments in the SEM.

Rigid‐plastic hybrid element analyses of the plane strain upsetting

AbstractA rigid‐plastic hybrid element method (HEM) for simulation of metal forming is developed. This method is a mixed approach of the rigid‐plastic domain‐BEM and the rigid‐plastic FEM based on the theory of compressible plasticity. Because the compatibilities of not only velocity but also velocity's derivative between the adjoining boundary elements and finite elements can be met, the velocities and the derivatives of the velocity can be calculated with the same precision for the rigid‐plastic HEM. Then, it is considered that the rigid‐plastic HEM is a more precise method in formulation than the conventional rigid‐plastic FEMs for which the compatibilities of velocity's derivative cannot be met. The plane strain upsetting processes with two friction factors are analyzed by the rigid‐plastic HEM in this article. © 2002 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 18: 726–737, 2002; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/num.10031.

Tidal mixing and trapping in mangrove swamps

Lateral trapping in mangrove swamps is a dominant process controlling longitudinal mixing in mangrove-fringed tidal rivers. In the dry season, the effective value of the longitudinal diffusivity is increased by the trapping effect by typically two orders of magnitude, from its value in the absence of swamps. In the wet season, freshwater is trapped within the swamp and the adjoining boundary in the tidal river, for long periods following the passage of a short-lived flood. This may have important ecological implications. A fluid-mud layer appears to be created by strong tidal currents over colloidal mangrove mud.

Triple lines in polycrystalline aggregates as disclinations

Abstract Triple lines in polycrystalline aggregates are lines where three grains meet. It is shown that these lines can be interpreted as disclinations if the relations between adjoining grain orientations are chosen as nearest-neighbour relations. These relations are needed for describing quantitatively the structure of the individual boundaries as dislocation networks. The disclination character of the triple line decides the dislocation balance between the adjoining boundaries, and so may imply differences in the physical character of different triple lines.

Nationalism in the History Textbooks of Yugoslavia and Bulgaria

Modern nations generally attach great importance to the teaching of history in their schools, for such instruction often serves as means to perpetuate and transmit the ideals and values inherent in their political forms of government. History is also frequently employed to justify government's action and to sanction its present conduct. Of all contemporary forms of government, communism-with view of itself as a science of society-has probably made the greatest use of history to serve political ends. The broad panorama of human history invariably is interpreted within MarxistLeninist framework which emphasizes the economic aspect of human life as the one great current in man's social and cultural development through the ages. This view applies from Hegelian philosophy the elements of thesis, antithesis, and synthesis, in terms of changing economic conditions, to describe society as predeterministic evolutionary succession of social orders, each one supposedly representing higher stage of human relationships: primitive life, slavery, feudalism, capitalism, socialism, and finally communism. Because of the importance of this interpretation of history to the communist state, the teaching of the subject in two communist nations has been selected for detailed analysis. In particular, the study seeks to determine what similarities and differences, if any, exist in content, interpretations, and procedures as result of the policies of each respective government. In order to limit the number of extraneous factors in the analysis, Yugoslavia and Bulgaria have been selected for the study. These are two Balkan, Slavic, Communist nations with adjoining boundaries and with many ethnic, cultural, linguistic, and historical similarities. The important variable lies in the fact that Yugoslavia is an independent communist country, whose leadership is not com itted to any particular power-block or alliance; while on the other hand, Bulgaria maint ins close political, social, and military ties with the Soviet Union and also holds membership in Comecon, the East European organization for trade and economic development.