scholarly journals Size regulation of multiple organelles competing for a shared subunit pool

2020 ◽  
Author(s):  
Deb Sankar Banerjee ◽  
Shiladitya Banerjee
Keyword(s):  
Growth Rate ◽  
Three Dimensional ◽  
Size Control ◽  
Size Regulation ◽  
Existing Structures ◽  
Pool Model ◽  
Single Structure ◽  
Multiple Structures ◽  
Stochastic Selection ◽  
Autocatalytic Growth

How cells regulate the size of intracellular structures and organelles, despite continuous turnover in their component parts, is a longstanding question. Recent experiments suggest that size control of many intracellular assemblies is achieved through the depletion of a limiting subunit pool in the cytoplasm. While the limiting pool model ensures organelle size scaling with cell size, it does not provide a mechanism for robust size control of multiple co-existing structures. Here we propose a kinetic theory for size regulation of multiple structures that are assembled from a shared pool of subunits. We demonstrate that a negative feedback between the growth rate and the size of individual structures underlies size regulation of a wide variety of intracellular assemblies, from cytoskeletal filaments to three-dimensional organelles such as centrosomes and the nucleus. We identify the feedback motifs for size control in these structures, based on known molecular interactions, and quantitatively compare our theory with available experimental data. Furthermore, we show that a positive feedback between structure size and growth rate can lead to bistable size distributions arising from autocatalytic growth. In the limit of high subunit concentration, autocatalytic growth of multiple structures leads to stochastic selection of a single structure, elucidating a mechanism for polarity establishment.

scholarly journals Computer-aided design of multi-purpose steel headframes for mines with a new technical level

2020 ◽  
Vol 174 ◽  
pp. 01048
Author(s):  
Elena Kassikhina ◽  
Vladimir Pershin ◽  
Nina Rusakova
Keyword(s):  
Cross Sections ◽  
Computer Aided Design ◽  
Information Technologies ◽  
Three Dimensional ◽  
Numerical Control ◽  
Technical Level ◽  
Resource Saving ◽  
Existing Structures ◽  
Set Up ◽  
Aided Design

The existing structures of the steel sinking headgear and permanent headframe do not meet the requirements of resource saving (metal consumption and manpower input at installation), and the present methods of the headframe designing do not fully reflect recent possibilities of applying of the advanced information technologies. Technical level of the modern software makes it possible for designers to set up multiple numerical experiments to create a computer simulation that allows solving the problem without field and laboratory experiments, and therefore without special costs. In this regard, a mathematical simulation has been developed and based on it, software to select cross-sections of multi- purpose steel headframe elements and to calculate proper weight of its metal structures depending on the characteristics and hoisting equipment. A headframe drawing is displayed, as the results of the software work, including list of elements, obtained optimal hoisting equipment in accordance with the initial data. The software allows speeding up graphic work and reducing manpower input on calculations and paper work. The software allows developing a three-dimensional image of the structure and its functional blocks, based on the obtained initial parameters, as well as developing control software for units with numerical control (NC) in order to manufacture multi-purpose headframes.

scholarly journals The Formation of a Cavity in a 3D Flux Rope

2013 ◽  
Vol 8 (S300) ◽  
pp. 147-150 ◽  
Author(s):  
Donald Schmit ◽  
Sarah Gibson
Keyword(s):  
Ad Hoc ◽  
Numerical Models ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Flux Rope ◽  
Multiple Structures ◽  
Field Lines ◽  
Hydrostatic Balance ◽  
Distinct Field ◽  
Three Dimensional Space

AbstractThere are currently no three dimensional numerical models which describe the magnetic and energetic formation of prominences self-consistently. Consequently, there has not been significant progress made in understanding the connection between the dense prominence plasma and the coronal cavity. We have taken an ad-hoc approach to understanding the energetic implications of the magnetic models of prominence structure. We extract one dimensional magnetic field lines from a 3D MHD model of a flux rope and solve for hydrostatic balance along these field lines incorporating field-aligned thermal conduction, uniform heating, and radiative losses. The 1D hydrostatic solutions for density and temperature are then mapped back into three dimensional space, which allows us to consider the projection of multiple structures. We find that the 3D flux rope is composed of several distinct field line types. A majority of the flux rope interior field lines are twisted but not dipped. These field lines are density-reduced relative to unsheared arcade field lines. We suggest the cavity may form along these short interior field lines which are surrounded by a sheath of dipped field lines. This geometric arrangement would create a cavity on top of a prominence, but the two structures would not share field lines or plasma.

Analysis of SiC CVD Growth in a Horizontal Hot-Wall Reactor by Experiment and 3D Modelling

2007 ◽  
Vol 556-557 ◽  
pp. 61-64
Author(s):  
Y. Shishkin ◽  
Rachael L. Myers-Ward ◽  
Stephen E. Saddow ◽  
Alexander Galyukov ◽  
A.N. Vorob'ev ◽  
...  
Keyword(s):  
Growth Rate ◽  
Growth Process ◽  
Three Dimensional ◽  
Chemical Species ◽  
3D Modelling ◽  
Complete Model ◽  
Cvd Growth ◽  
Dimensional Simulation ◽  
Insight Into ◽  
Hot Zone

A fully-comprehensive three-dimensional simulation of a CVD epitaxial growth process has been undertaken and is reported here. Based on a previously developed simulation platform, which connects fluid dynamics and thermal temperature profiling with chemical species kinetics, a complete model of the reaction process in a low pressure hot-wall CVD reactor has been developed. Close agreement between the growth rate observed experimentally and simulated theoretically has been achieved. Such an approach should provide the researcher with sufficient insight into the expected growth rate in the reactor as well as any variations in growth across the hot zone.

A Simple Statistical Theory for Grain Growth in Materials.

1990 ◽  
Vol 209 ◽  
Author(s):  
P. Mulheran ◽  
J.H. Harding
Keyword(s):  
Growth Rate ◽  
Monte Carlo ◽  
Statistical Theory ◽  
Stochastic Model ◽  
Grain Growth ◽  
Three Dimensional ◽  
Monte Carlo Procedure ◽  
Short Time ◽  
2D And 3D ◽  
Good Agreement

A Monte Carlo procedure has been used to study the ordering of both two and three dimensional (2d and 3d) Potts Hamiltonians, further to the work of Anderson et al. For the 3d lattice, the short time growth rate is found to be much slower than previously reported, though the simulated microstructure is in agreement with the earlier studies. We propose a new stochastic model that gives good agreement with the simulations.

Three-Dimensional Instability of Opposite Polarity Nonthermal Dusty Plasma

2019 ◽  
Vol 74 (2) ◽  
pp. 131-138
Author(s):  
E.K. El-Shewy ◽  
S.K. Zaghbeer ◽  
A.A. El-Rahman
Keyword(s):  
Growth Rate ◽  
Cyclotron Frequency ◽  
Three Dimensional ◽  
Dusty Plasmas ◽  
Opposite Polarity ◽  
Charge Ratio ◽  
Nonlinear Phenomena ◽  
Wave Instability ◽  
Direction Cosines ◽  
Dimensional Instability

AbstractNonlinearity properties of obliquely wave propagation and instability in collisionless magnetized nonthermal dusty plasmas containing fluid of negative-positive grains are investigated. Zakharov-Kuznetsov equation is obtained and the three-dimensional wave instability is studied. The parameters such as polarity charge ratio, cyclotron frequency and fast nonthermal effectiveness of the instability properties and growth rate are theoretically studied. It is found that both positive and negative soliton profiles are formed depending on the fraction ratio of electron-ion nonthermality. Also, the growth rate was dependent nonlinearly on the direction cosines, the cyclotron frequency and the positive (negative) grain charge ratio, but independent of the fractional ratio of electron-ion nonthermality. Present discussion may be very significant regarding the observations of nonlinear phenomena in space.

scholarly journals Creation of virtual 3D models of the existing architectonic structures using the web resources

Spatium ◽  
2016 ◽  
pp. 30-36 ◽  
Author(s):  
Petar Pejic ◽  
Sonja Krasic
Keyword(s):  
Laser Scanning ◽  
Three Dimensional ◽  
3D Models ◽  
Three Dimensional Model ◽  
Web Resources ◽  
Existing Structures ◽  
Software Packages ◽  
Physical Presence ◽  
The Creation ◽  
Three Dimensional Models

Digital three-dimensional models of the existing architectonic structures are created for the purpose of digitalization of the archive documents, presentation of buildings or an urban entity or for conducting various analyses and tests. Traditional methods for the creation of 3D models of the existing buildings assume manual measuring of their dimensions, using the photogrammetry method or laser scanning. Such approaches require considerable time spent in data acquisition or application of specific instruments and equipment. The goal of this paper is presentation of the procedure for the creation of 3D models of the existing structures using the globally available web resources and free software packages on standard PCs. This shortens the time of the production of a digital three-dimensional model of the structure considerably and excludes the physical presence at the location. In addition, precision of this method was tested and compared with the results acquired in a previous research.

A RHEED Study of MBE Growth of ZnSe on GaAs (111) A-(2 × 2)

2003 ◽  
Vol 10 (04) ◽  
pp. 669-675
Author(s):  
F. S. Gard ◽  
J. D. Riley ◽  
R. Leckey ◽  
B. F. Usher
Keyword(s):  
Growth Rate ◽  
Electron Diffraction ◽  
Substrate Temperature ◽  
Three Dimensional ◽  
High Energy ◽  
Growth Mode ◽  
Two Dimensional ◽  
High Energy Electron ◽  
Mbe Growth ◽  
Atomic Flux

ZnSe epilayers have been grown under various Se/Zn atomic flux ratios in the range of 0.22–2.45 at a substrate temperature of 350°C on Zn pre-exposed GaAs (111) A surfaces. Real time reflection high energy electron diffraction (RHEED) observations have shown a transition from a two-dimensional (2D) to a three-dimensional (3D) growth mode. The transition time depends directly upon the growth rate. A detailed discussion is presented to explore the cause of this change in the growth mode.

Growth Rate of the Vomer in Normal and Cleft Lip and Palate Human Fetal Specimens

1992 ◽  
Vol 29 (1) ◽  
pp. 38-43 ◽  
Author(s):  
Kyle R. Kimes ◽  
Mark P. Mooney ◽  
Michael I. Siegel ◽  
John S. Todhunter
Keyword(s):  
Growth Rate ◽  
Cleft Lip ◽  
Cleft Lip And Palate ◽  
Three Dimensional ◽  
Growth Curves ◽  
Reconstruction Technique ◽  
Linear Component ◽  
Volumetric Growth ◽  
Significant Difference ◽  
Postmenstrual Age

The present study, part of an ongoing investigation of normal and dysmorphic development of the human fetal oronasal capsule, examined the rate of growth of the vomer. For comparative purposes, 29 human fetal specimens (20 “normal” and 9 cleft lip and palate [CLP]) were celloidin embedded, sectioned, stained with hematoxylin and eosin, and serially digitized. The specimens ranged from 8 to 21 weeks in postmenstrual age. The application of a well-documented three-dimensional reconstruction technique provided quantification of several aspects of the vomer. CLP vomer length and volume were growing at a faster rate In the 8 to 21 week age range. Growth curves were produced by plotting length and volume against postmenstrual age and a significant difference was noted between the slopes (growth rate) of the linear component of the normal and CLP growth curves for vomer length (p < .001) and volume (p < .001). This study tested the hypothesis of a more rapidly growing 8 to 21 week CLP vomer and observed that the growth trends of the CLP vomer are similar to those of the CLP nasal septum, which also was found to possess a significantly larger (p < .001) volumetric growth rate throughout the course of the vomer. Comparative findings suggest that a pathogenetic correlate of CLP is the rapid enlargement of the midline structures of the oral and nasal capsules.

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