Optimal Cell Size Research Articles

A Nonuniform Cell Partition for the Analysis of Nonlinear Stochastic Systems

This paper presents a study of nonuniform cell partition for analyzing the response of nonlinear stochastic systems by using the generalized cell mapping (GCM) method. The necessity of nonuniform cell partition for nonlinear systems is discussed first. An ad hoc scheme is then presented for determining optimal cell sizes based on the statistical analysis of the GCM method. The proposed nonuniform cell partition provides a roughly uniform accuracy for the estimate of the one-step transition probability density function over a large region in the state space where the system varies significantly from being linear to being strongly nonlinear. The nonuniform cell partition is shown to lead to more accurate steady-state solutions and enhance the computational efficiency of the GCM method.

Coulomb effect in cell projection lithography

Beam blurring due to Coulomb effects is very important in cell projection lithography. This article reports on Coulomb effects in cell projection lithography by simulation and experiment, and shows some important results. First, the Coulomb effect in a single cell is substantially uniform in conventional cell projection optics. Second, refocusing is effective in reducing the space charge effect even in Koehler illumination with a Gaussian crossover. Third, the optimum cell size in the case of a large aperture percentage depends on the ratio of the total exposure time in the peripheral circuit to the total settling time in the memory cell mat. In addition, a modified mask technique is proposed to decrease the influence of Coulomb effects on throughput.

APPLICATION OF INTERPOLATED CELL MAPPING TO AN ANALYSIS OF THE LORENZ EQUATIONS

The Lyapunov exponents of the Lorenz equations are calculated using interpolated cell mapping. The effects of mapping time step and cell size on accuracy and computation time are analyzed, leading to the identification of optimal cell size and time step values. A higher order interpolation method for interpolated cell mapping is described. The accuracy and computation time of this method are compared to numerical integration for calculating the basins of attraction of the Lorenz equations and the dimension of the basin boundaries. Regions of state space with high levels of deformation are shown to exist where the basin boundaries are most dense.

Flow cytometric measurement of NK cell immunoconjugates by pulse width processing.

Pulse width analysis, in flow cytometry, has been widely used for optimal cell size resolution in cell kinetics analysis. Pulses, generated by scattered light or fluorescence of cells, are electronically analyzed for their height and width. The information generated from these two properties of the pulses is utilized to distinguish signals from single cells vs. signals from cell clumps or aggregates. Pulse width, unlike pulse height, is more sensitive to differences in cell diameter, and therefore can discriminate very small differences in it, which pulse height cannot. We have exploited this property of pulse widths to measure immunoconjugates between NK cells and their targets. Discrimination of the free target cells from the conjugated ones is possible by the pulse widths of only light scatter signals, both forward and/or orthogonal. This resolution was not obtained if pulse height of the same signals was visualized. Using this resolution it was possible to distinguish single cells from the aggregates between target and effector cells. We propose that this is a better method for distinguishing conjugates than the method in which prior vital staining of cells is used.

Optimum cell size and density of brittle foams

Optimum cell size and density of brittle foams

Regional geochemical data compilation and map preparation, Labrador, Canada

Abstract Procedures used to compile geochemical data for some 20,000 lake sediment and stream sediment samples from 292,000 km 2 in Labrador, Canada, are described. A methodology for integrating the lake and stream sediment data is developed which compensates for the varying organic component in the matrix of the two sample media. It is shown that this procedure is effective in reducing the variability of the Zn and Ni data due to the organic matrix effect and for normalizing the data for regionalscale comparisons. No compensation was required for U data. In order to generate geochemical maps of the broad-scale patterns in the data, reflecting such features as structural provinces, litho-tectonic packages and metallogenic provinces, the use of medians for the data falling within square cells with a side varying from 10 to 50 km was investigated. An Analysis of Variance procedure is described which was used to select an optimal cell size. For the Labrador data 25×25 km cells were selected, resulting in a 97% reduction in the volume of data to be managed. The reduced data contained approximately 35%, 70% and 55% of the information for Zn, Ni and U, respectively. The final maps appear to reflect major features of the regional geochemistry related to the geological history of Labrador. It is proposed that the procedures developed should be further evaluated to determine their suitability in fulfilling the objectives of IGCP Project 259 on International Geochemical Mapping.

Cell size and RNA content correlate with cell differentiation and proliferative capacity of rat keratinocytes

Keratinocytes from rat skin were separated according to their size in a specially designed unit-gravity sedimentation chamber. The fractions obtained with this technique showed clear morphological differences, and analysis of size distribution confirmed that size was the criterion for separation. Simultaneous DNA and RNA staining of the fractions with acridine orange and subsequent flow cytometric analysis enabled one to classify cells into resting, proliferating, and differentiating stages. Cell size was not directly correlated with proliferation in situ as determined with acridine orange flow cytometry, nor with proliferative capacity in culture as assayed by BrdU/Hoechst flow cytometry. The smallest cells, exhibiting low DNA and RNA content, which do not proliferate in vivo, required a prolonged period of serum stimulation in vitro to initiate RNA and DNA synthesis. Cells of intermediate size exhibited early RNA synthesis and maximal proliferative capacity, whereas the largest cell population displayed no RNA synthesis in culture and the least proliferative capacity. In conclusion, these results suggest that RNA synthesis early after serum stimulation, in addition to a specific, optimal cell size, correlates with the proliferative capacity of keratinocytes in cell culture.

Improving Productivity with Group Technology

The paper looks first at the various types of classification and coding methods used in group technology. A discussion is provided on the pros and cons of classification and its relevance and significance to the establishment of cellular manufacturing. Secondly, the formation of production cells is examined. Some of the factors considered include the optimum cell size, the effect of numerically‐controlled machines, and quality assurance. The introduction of GT (group technology) cells imposes a marked change in the role of the foreman and working relationship of the operators. The social aspect of GT is discussed against the background of current motivational theories and results from surveys are presented.

Optimum Cell Size for the Storage of Messages

In this paper we discuss a memory allocation problem first introduced by Wolman in [1] (see also [2]). A general solution formula is presented, from which closed form expressions for a few special cases may be easily derived.

A cofferdam design optimization

The design of circular type cellular cofferdams is formulated as a nonlinear optimization model that takes explicit account of relevant economic and technologic aspects. The objective is minimization of total expected cost. The constraints arise from stability critera to protect against failures due to slipping of the sheet piles on the river side and interlock stresses at the joint. A solution achieved with geometric programming techniques, yields optimal cell sizes and design heights. The geometric programming approach provides important design insights by yielding the proportions of the total cost to be assigned to the cost components, fill material, sheet piling and flooding in an optimal design.

Optimization of Seismic Reconnaissance Surveys in Petroleum Exploration

The seismic reflection method employed in petroleum exploration is described, after which the problem of selecting the optimum cell size for a uniform rectangular seismic reconnaissance search pattern is stated in terms of elementary search theory. The search effectiveness for each pattern is estimated by a Monte Carlo approach due to the probabilistic nature of target geometry. The problem of allocating a limited amount of search effort to a number of regions to be searched simultaneously is formulated as a dynamic programming problem in which the decision variables are the search pattern parameters and the inter-shot point spacing along the survey lines. The approach is easily generalized so that pattern morphology and orientation also become decision variables.

Contagious Occupancy

SUMMARY In the Occupancy theory of distribution of elements into a set of “boxes” (alias intervals, cells, groups, categories, subsets, compartments, etc.) the random distribution (a) is contrasted with distributions reflecting (b) heterogeneity, (c) limitation on the number of elements which may be contained in a box, or (d) a mixture of these. The following models are proposed, n balls being assumed dropped into N boxes. The distribution of the number of boxes containing no balls is obtained assuming the individual distribution in a single box is (a) Poisson, (b) Negative Binomial, (c) Positive Binomial, (d) Positive Binomial with varying probability. The large sample powers of the Index of Dispersion and the Zeros Test are compared in regard of these alternatives and the question of optimum cell size is dealt with.