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Results 451 - 500 of 1889
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Tozaki Hirokazu - - 2008
Single-cell-level behaviors of cells are typically inferred from ensemble measurements. However, such inferences implicitly assume a biological version of ergodicity: the percentage of cells in a state is identical to the probability to find a cell in that state. While the ergodicity does not always hold, it has been rarely ...
Araújo N A M - - 2008
We study the effect of the presence of a regular substrate pattern on the irreversible adsorption of nanosized and colloid particles. Deposition of disks of radius r(0) is considered, with the allowed regions for their center attachment at the planar surface consisting of square cells arranged in a square lattice ...
Xu Min - - 2008
A unified Mie and fractal model for light scattering by biological cells is presented. This model is shown to provide an excellent global agreement with the angular dependent elastic light scattering spectroscopy of cells over the whole visible range (400 to 700 nm) and at all scattering angles (1.1 to ...
Klein Allon M AM Cavendish Laboratory, Madingley Road, Cambridge CB3 OHE, United - - 2008
The dynamics of a genetically labeled cell population may be used to infer the laws of cell division in mammalian tissue. Recently, we showed that in mouse tail skin, where proliferating cells are confined to a two-dimensional layer, cells proliferate and differentiate according to a simple stochastic model of cell ...
Khan Adil G - - 2008
Many species of mammals are very good at categorizing odors. One model for how this is achieved involves the formation of "attractor" states in the olfactory processing pathway, which converge to stable representations for the odor. We analyzed the responses of rat olfactory bulb mitral/tufted (M/T) cells using stimuli "morphing" ...
Wong Amy P - - 2008
Accurate modeling of the cellular microenvironment is important for improving studies of cell biology in vitro. Here, we demonstrate a flexible method for creating a cellular microenvironment in vitro that allows (i) controlled spatial distribution (patterning) of multiple types of cells within three-dimensional (3-D) matrices of a biologically derived, thermally ...
Tomelleri C - - 2008
OBJECTIVES: In this study, we quantify growth variability of tumour cell clones from a human leukaemia cell line. MATERIALS AND METHODS: We have used microplate spectrophotometry to measure growth kinetics of hundreds of individual cell clones from the Molt3 cell line. Growth rate of each clonal population has been estimated ...
Zajac Mark - - 2008
Cell crawling is an inherently physical process that includes protrusion of the leading edge, adhesion to the substrate, and advance of the trailing cell body. Research into advance of the cell body has focused on actomyosin contraction, with cytoskeletal disassembly regarded as incidental, rather than causative; however, extracts from nematode ...
Currie, David
This work concerns the modelling of the dielectric properties of biological cell suspensions. The relative permittivity of a suspension is proportional to the volume fraction of suspended cells but it would be more useful to know the average cell radius and number density separately. A non-linear least squares algorithm, based ...
Hines Michael L - - 2008
Neuron tree topology equations can be split into two subtrees and solved on different processors with no change in accuracy, stability, or computational effort; communication costs involve only sending and receiving two double precision values by each subtree at each time step. Splitting cells is useful in attaining load balance ...
Wang, Yang
My dissertation researches are on the field of fuel cell materials and fuel cell modeling. During my dissertation research, I authored two US patent applications and have developed several innovative approaches to new fuel cell materials, novel fuel cell hybrid power device and an original fuel cell modeling method. A ...
Biktashev Vadim N - - 2008
We aim to understand the formation of abnormal waves of activity from myocardial regions with diminished cell-to-cell coupling. En route to this goal, we studied the behavior of a heterogeneous myocyte network in which a sharp coupling gradient was placed under conditions of increasing network automaticity. Experiments were conducted in ...
Wurdinger Thomas - - 2008
Luciferases are widely used to monitor biological processes. Here we describe the naturally secreted Gaussia princeps luciferase (Gluc) as a highly sensitive reporter for quantitative assessment of cells in vivo by measuring its concentration in blood. The Gluc blood assay complements in vivo bioluminescence imaging, which has the ability to ...
Fernandez-Capetillo Oscar - - 2008
In response to DNA double-stranded breaks (DSBs) cells activate a signaling cascade known as the DNA damage response (DDR) whose main function is to promote the repair of the lesions while it delays cell cycle progression until repair is completed. Whereas most cells respond alike to an equivalent dose of ...
Satulovsky Javier - - 2008
We have developed a top-down, rule-based mathematical model to explore the basic principles that coordinate mechanochemical events during animal cell migration, particularly the local-stimulation-global-inhibition model suggested originally for chemotaxis. Cells were modeled as a shape machine that protrudes or retracts in response to a combination of local protrusion and global ...
Mtibaa Riadh - - 2008
We propose a computational model of perceptual grouping for explaining the 3D shape representation of an illusory percept called "mime effect." This effect is associated with the generation of an illusory, volumetric perception that can be induced by particular distributions of inducing stimuli such as cones, whose orientations affect the ...
Rejniak Katarzyna A KA Division of Mathematics, University of Dundee, Dundee, DD1 4HN, Scotland, UK. - - 2008
Normal hollow epithelial acini are 3-dimensional culture structures that resemble the architecture and functions of normal breast glands and lobules. This experimental model enables in vitro investigations of genotypic and molecular abnormalities associated with epithelial cancers. However, the way in which the acinar structure is formed is not yet completely ...
Dieterich Peter - - 2008
Cell movement--for example, during embryogenesis or tumor metastasis--is a complex dynamical process resulting from an intricate interplay of multiple components of the cellular migration machinery. At first sight, the paths of migrating cells resemble those of thermally driven Brownian particles. However, cell migration is an active biological process putting a ...
J. Holis
This paper deals with the application of High Altitude Platforms for the provision of third generation mobile services in sparsely-populated areas or in developing countries. It focuses on the behavior of large cells provided via a multiple HAP deployment and shows the possibilities of using small cells located inside these ...
Sokalski, Tomasz
Fuel Cells Science and Technology 2008, Scientific Advances in Fuel Cell Systems, Copenhagen, 8-9 October, 2008
Philipps, S.P.
In this letter a calibrated numerical model of a III-V dualjunction solar cell including tunnel diode and Bragg reflector is presented. The quantum efficiencies of the subcells are computed by using the principle of current-limitation in monolithic multi-junction solar cells. A special procedure with bias-illumination and bias-voltage was implemented. Numerical ...
Fisher, Jasmin
We introduce bounded asynchrony, a notion of concurrency tailored to the modeling of biological cell-cell interactions. Bounded asynchrony is the result of a scheduler that bounds the number of steps that one process gets ahead of other processes; this allows the components of a system to move independently while keeping ...
Pflug, A.
Parallel plate reactors for plasma activated chemical vapor deposition (PACVD) of a-Si:H/µc-Si:H are an established technology for the fabrication of thin film solar cells based on a-Si:H as well as a-Si:H/µc-Si:H tandem solar cells. In solar cell fabrication lines, a high deposition rate and a rate homogeneity better than 5% ...
Sandersius Sebastian A - - 2008
Recently, the Subcellular Element Model (SEM) has been introduced, primarily to compute the dynamics of large numbers of three-dimensional deformable cells in multicellular systems. Within this model framework, each cell is represented by a collection of elastically coupled elements, interacting with one another via short-range potentials, and dynamically updated using ...
Hatzikirou Haralambos - - 2008
Understanding the precise interplay of moving cells with their typically heterogeneous environment is crucial for central biological processes as embryonic morphogenesis, wound healing, immune reactions or tumor growth. Mathematical models allow for the analysis of cell migration strategies involving complex feedback mechanisms between the cells and their microenvironment. Here, we ...
Yang Liu - - 2008
BACKGROUND: Many cellular processes involve substantial shape changes. Traditional simulations of these cell shape changes require that grids and boundaries be moved as the cell's shape evolves. Here we demonstrate that accurate cell shape changes can be recreated using level set methods (LSM), in which the cellular shape is defined ...
Möhler Lars - - 2008
To describe the growth behavior of anchorage-dependent mammalian cells in microcarrier systems, various approaches comprising deterministic and stochastic single cell models as well as automaton-based models have been presented in the past. The growth restriction of these often contact-inhibited cells by spatial effects is described at levels with different complexity ...
Anderson Eric J - - 2008
To date, no published study has examined quantitatively the effect of geometric and dimensional idealization on prediction of the mechanical signals imparted by fluid drag to cell surfaces. We hypothesize that this idealization affects the magnitude and range of imparted forces predicted to occur at a subcellular level. Hence, we ...
Altenburger Rolf - - 2008
Growth assays with unicellular green algae are an established tool in ecotoxicological effect assessment for chemicals and environmental samples. From an ecological perspective it seems appropriate to use the growth rate as a process variable rather than a measure of biomass gain for calculating inhibitory effects of contaminants. The notion ...
Veening Jan-Willem - - 2008
Clonal populations of microbial cells often show a high degree of phenotypic variability under homogeneous conditions. Stochastic fluctuations in the cellular components that determine cellular states can cause two distinct subpopulations, a property called bistability. Phenotypic heterogeneity can be readily obtained by interlinking multiple gene regulatory pathways, effectively resulting in ...
Peterson Craig L - - 2008
INTRODUCTIONCore histones can be purified from a variety of cell sources, including Drosophila embryos, HeLa tissue culture cells, calf thymus, or chicken erythrocytes. Chick erythrocytes are an excellent source of cellular histones: Large quantities of source material are readily obtainable, the purified histones have low levels of post-translational modifications, and ...
Sowiński Paweł - - 2008
C(4) photosynthesis involves cell-to-cell exchange of photosynthetic intermediates between the Kranz mesophyll (KMS) and bundle sheath (BS) cells. This was believed to occur by simple diffusion through plentiful plasmodesmatal (PD) connections between these cell types. The model of C(4) intermediates' transport was elaborated over 30 years ago and was based ...
Takagi Hiroaki - - 2008
Cells can show not only spontaneous movement but also tactic responses to environmental signals. Since the former can be regarded as the basis to realize the latter, playing essential roles in various cellular functions, it is important to investigate spontaneous movement quantitatively at different physiological conditions in relation to a ...
Moreno Daniel - - 2008
The aim of the present work was to describe the antiproliferative effect of camptothecin (CPT), topotecan (TPT) and cisplatin (CIS) in cultured cells using a semi-mechanistic pharmacodynamic approach. This effect on the growth of DHD-K12PROb cells was modelled as a function of drug concentration and time of exposure using the ...
Kachouie Nezamoddin N - - 2008
Cell segmentation and/or localization is the first stage of a (semi)automatic tracking system. We addressed the cell localization problem in our previous work where we characterized a typical blood stem cell in a microscopic image as an approximately circular object with dark interior and bright boundary. We also addressed the ...
Luo Yong - - 2008
Given that macrophages can proliferate and that certain microbes survive inside phagocytic cells, the question arises as to the post-mitotic distribution of microbial cargo. Using macrophage-like cells we evaluated the post-mitotic distribution of intracellular Cryptococcus yeasts and polystyrene beads by comparing experimental data to a stochastic model. For beads, the ...
Chang Robert - - 2008
Novel technologies are emerging that incorporate cells as part of the building blocks for various biomanufacturing processes, such as solid freeform fabricated tissue constructs for tissue regeneration, three-dimensional pharmacokinetic models, cell-based microelectromechanical systems, sensors, and microfluidic devices. However, the effects of these biomanufacturing processes on cells have not been fully ...
Newman Timothy J - - 2008
This paper is comprised of two parts. In the first we provide a brief overview of grid-free methods for modeling multicellular systems. We focus on an approach based on Langevin equations, in which inertia is ignored, and stochastic effects on cell motion are included. The discussion starts with simpler models, ...
El-Manzalawy Yasser - - 2008
Identifying B-cell epitopes play an important role in vaccine design, immunodiagnostic tests, and antibody production. Therefore, computational tools for reliably predicting B-cell epitopes are highly desirable. We explore two machine learning approaches for predicting flexible length linear B-cell epitopes. The first approach utilizes four sequence kernels for determining a similarity ...
Ersoy I - - 2008
Cell adhesion and spreading within the extracellular matrix (ECM) plays an important role in cell motility, cell growth and tissue organization. Measuring cell spreading dynamics enables the investigation of cell mechanosensitivity to external mechanical stimuli, such as substrate rigidity. A common approach to measure cell spreading dynamics is to take ...
Arkhipov Sergey N - - 2008
T cells of the immune system target infected and tumor cells in crowded tissues with high precision by coming into direct contact with the intended target and orienting the intracellular Golgi apparatus and the associated organelles to the area of the cell-cell contact. The mechanism of this orientation remains largely ...
El-Kareh Ardith W - - 2008
A pharmacokinetic-pharmacodynamic mathematical model is developed for cellular pharmacology of chemotherapeutic drugs for which the decisive step towards cell death occurs at a point in the cell cycle, presumably corresponding to a cell cycle checkpoint. For each cell, the model assumes a threshold level of some intracellular species at that ...
Kilian H G - - 2008
An increment model based on thermodynamics lays bare that the cell size distributions of archaea, prokaryotes and eukaryotes are optimized and belong to the same universal class. Yet, when a cell absorbs mass or signals are processed, these conditions are disturbed. Relaxation re-installs ideal growth conditions via an exponential process ...
Peralta X G - - 2008
Dorsal closure is an essential stage of Drosophila development that is a model system for research in morphogenesis and biological physics. Dorsal closure involves an orchestrated interplay between gene expression and cell activities that produce shape changes, exert forces and mediate tissue dynamics. We investigate the dynamics of dorsal closure ...
Sun Tao - - 2007
Closely coupled in vitro and in virtuo models have been used to explore the self-organization of normal human keratinocytes (NHK). Although it can be observed experimentally, we lack the tools to explore many biological rules that govern NHK self-organization. An agent-based computational model was developed, based on rules derived from ...
Chappell M J MJ School of Engineering, University of Warwick, Coventry, UK. - - 2008
A model describing the response of the growth of single human cells in the absence and presence of the anti-cancer agent topotecan (TPT) is presented. The model includes a novel coupling of both the kinetics of TPT and cell cycle responses to the agent. By linking the models in this ...
Chang Robert - - 2007
Novel technologies are emerging that incorporate cells as part of the building blocks for various biomanufacturing processes, such as solid freeform fabricated tissue constructs for tissue regeneration, three-dimensional pharmacokinetic models, cell-based microelectromechanical systems, sensors, and microfluidic devices. However, the effects of these biomanufacturing processes on cells have not been fully ...
Farhadifar Reza - - 2007
BACKGROUND: Epithelial junctional networks assume packing geometries characterized by different cell shapes, neighbor number distributions and areas. The development of specific packing geometries is tightly controlled; in the Drosophila wing epithelium, cells convert from an irregular to a hexagonal array shortly before hair formation. Packing geometry is determined by developmental ...
Quilot Bénédicte - - 2008
The number of cells and the mean cell volume in the mesocarps of fruits from peach genotypes with different percentages of the genome of Prunus davidiana, a wild, related, species, were evaluated. The mesocarp mass varied greatly between the four groups of genotypes. The mean cell volume and the number ...
Miyamoto, Kiyoshi
Thesis--University of Tsukuba, D.Sc.(B), no. 447, 1988. 3. 25
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