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Results 401 - 450 of 1894
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Balasubramanian Lavanya - - 2008
Impedance of renal vascular smooth muscle cells (VSMCs) cultured on microelectrodes was measured by electric cell-substrate impedance sensing. Changes in measured impedance as a function of frequency were compared with the calculated values obtained from an extended cell-electrode model to estimate the junctional resistance, distance between the ventral cell surface ...
Shen Xiling - - 2008
A closed-loop control system drives progression of the coupled stalked and swarmer cell cycles of the bacterium Caulobacter crescentus in a near-mechanical step-like fashion. The cell-cycle control has a cyclical genetic circuit composed of four regulatory proteins with tight coupling to processive chromosome replication and cell division subsystems. We report ...
Shahrezaei Vahid - - 2008
Cell behaviour and the cellular environment are stochastic. Phenotypes vary across isogenic populations and in individual cells over time. Here we will argue that to understand the abilities of cells we need to understand their stochastic nature. New experimental techniques allow gene expression to be followed in single cells over ...
Feng Yusheng - - 2008
The ultimate goal of cancer treatment utilizing thermotherapy is to eradicate tumors and minimize damage to surrounding host tissues. To achieve this goal, it is important to develop an accurate cell damage model to characterize the population of cell death under various thermal conditions. The traditional Arrhenius model is often ...
Beck, N.
The missing correlation between film characteristics and <i>α</i>-Si:H-based <i>p-i-n</i> solar cells is still a controversial subject. The authors present a new parameter <i>µ</i><sup>0</sup><i>τ</i><sup>0</sup>, evaluated from steady-state transport measurements on <i>a</i>-Si:H layers, which can indeed relate film quality and cell performance as far as the latter is limited by the quality ...
Ahmed Tanvir - - 2008
We present novel microfluidic experiments to quantify population-scale transport parameters (chemotactic sensitivity chi(0) and random motility mu) of a population of bacteria. Previously, transport parameters have been derived theoretically from single-cell swimming behavior using probabilistic models, yet the mechanistic foundations of this upscaling process have not been verified experimentally. We ...
Pawar Parag - - 2008
Polymorphonuclear leukocyte (PMN) recruitment to sites of inflammation is initiated by selectin-mediated PMN tethering and rolling on activated endothelium under flow. Cell rolling is modulated by bulk cell deformation (mesoscale), microvillus deformability (microscale), and receptor-ligand binding kinetics (nanoscale). Selectin-ligand bonds exhibit a catch-slip bond behavior, and their dissociation is governed ...
Rosenfeld, D.
The dynamic structure of the atmospheric marine boundary layer (MBL) supports two distinct states of cloud cover: closed and open Benard cellular convection. Closed cells are nearly fully cloud covered, while the open cells have <40% cloud cover. Here we show that aerosols have a greater than expected impact on ...
Deguchi Shinji - - 2009
Previous studies on the intracellular force balance that forms the adherent cell structure have paid much attention to the mechanical behavior of cells seen in the horizontal project plane. By contrast, there are only few quantitative considerations on that in the vertical plane. Particularly, the contribution of the nucleus to ...
Itoh, Takayuki
This article presents a computational method for generating organic textures. The method first tessellates a region into a set of pseudo-Voronoi polygons using a particle model and then generates the detailed geometry of each of the polygons using Loop's subdivision surface with fractal noise. Unlike previous particle models-which are designed ...
Rebora, N.
Rain cells are structures which represent an important component of convective precipitation and a study of their properties represents a necessary step both towards improved stochastic models of small-scale precipitation and for the verification of deterministic high resolution local-area models. The case of intense convective precipitation in the tropics has ...
Yasuhiro Naito
Keywords: E-Cell, Kyoto model, cell simulation, ion channel
Awazu Akinori - - 2008
Dynamical aspects of the asymmetric cellular automata were investigated to consider the signaling processes in biological systems. As a meta-model of the cascade of feed-forward loop type network motifs in biological reaction networks, we consider the one dimensional asymmetric cellular automata where the state of each cell is controlled by ...
Kepseu W D - - 2008
In this paper, numerical simulation of calcium waves in a network of cells coupled together by a paracrine signaling is investigated. The model takes into account the long-range interaction between cells due to the action of extracellular messengers, which provide links between first-neighbor cells, but also on cells located far ...
Bansaye, Vincent
We consider a branching model introduced by Kimmel for cell division with parasite infection. Cells contain proliferating parasites which are shared randomly between the two daughter cells when they divide. We determine the probability that the organism recovers, meaning that the asymptotic proportion of contaminated cells vanishes. We study the ...
Jong-O Lee, Johanna Rosenfield, ...
Since BoNTs are potential biothreat agents, efforts are being made to develop therapeutic countermeasures for which sensitive in vitro models are required to evaluate the efficacy of potential therapeutic agents. In this report, we tested human neuroblastoma cell lines for their susceptibility to BoNT toxicity and demonstrated the application of ...
Belmonte Julio M - - 2008
A self-propelled particle model is introduced to study cell sorting occurring in some living organisms. This allows us to evaluate the influence of intrinsic cell motility separately from differential adhesion with fluctuations, a mechanism previously shown to be sufficient to explain a variety of cell rearrangement processes. We find that ...
Chavoya Arturo - - 2008
Cell pattern generation has a fundamental role in both artificial and natural development. This paper presents results from a model in which a genetic algorithm (GA) was used to evolve an artificial regulatory network (ARN) to produce predefined 2D cell patterns through the selective activation and inhibition of genes. The ...
Zhang, Jihui
Cell sectorization is a promising method for improving the capacity of code division multiple access (CDMA) systems. It has been shown that the use of adaptive antenna arrays with dynamic cell sectoring is particularly suitable for non-uniformly distributed users. In this paper, we present a novel Cluster-based sectoring algorithm for ...
Debeir Olivier - - 2008
In vitro cell imaging is a useful exploratory tool for cell behavior monitoring with a wide range of applications in cell biology and pharmacology. Combined with appropriate image analysis techniques, this approach has been shown to provide useful information on the detection and dynamic analysis of cell events. In this ...
Edd Jon F - - 2008
Encapsulation of cells within picolitre-size monodisperse drops provides new means to perform quantitative biological studies on a single-cell basis for large cell populations. Variability in the number of cells per drop due to stochastic cell loading is a major barrier to these techniques. We overcome this limitation by evenly spacing ...
Bouyer Daniel - - 2008
Trichome patterning in Arabidopsis serves as a model system to study how single cells are selected within a field of initially equivalent cells. Current models explain this pattern by an activator-inhibitor feedback loop. Here, we report that also a newly discovered mechanism is involved by which patterning is governed by ...
Bansaye, Vincent
We consider a branching model introduced by Kimmel for cell division with parasite infection. Cells contain proliferating parasites which are shared randomly between the two daughter cells when they divide. We determine the probability that the organism recovers, meaning that the asymptotic proportion of contaminated cells vanishes. We study the ...
Henneman S - - 2008
This review describes the mechanical and biological signalling pathways during orthodontic tooth movement and provides an update of the current literature. A theoretical model is introduced to elucidate the complex cascade of events after the application of an orthodontic force to a tooth. In this model, the events are divided ...
Chen Hsiu-Hung - - 2008
Light microscopy method offers unique abilities for the determination of membrane transport properties of either single or multiple cells. A stream imaging system composed of a microfluidic device, a charge-coupled device camera, and a microscope has been developed to study the osmotic behavior of multiple cells in response toward their ...
Holmes Raquell M - - 2008
Through live cell imaging and computational modeling, Neves et al. (2008) demonstrate that molecular interactions alone are insufficient to explain the patterns of MAPK activation: a model must include the cell morphology and spatial distribution of signaling molecules.
Zeng Yan - - 2008
Micropatterning of two different cell types based on surface modification allows spatial control over two distinct cell subpopulations. This study considers a micropatterned coculture system, which has release and absorption parts alternately arranged at the base, and each part has a single cell type. A micropattern unit was defined and ...
Rahman A R A - - 2008
We report on the impedance mapping of in vitro cellular morphology by electrical impedance spectroscopy, using microelectrodes. A micro multielectrode system was designed, fabricated, assembled, tested and demonstrated for the monitoring of anchorage-dependent cell behavior and morphology. This system allowed continuous, label-free, quantitative monitoring and visualization of cell adhesion, spreading, ...
Krzyzanski Wojciech - - 2008
A new class of basic indirect pharmacodynamic models for agents that alter the loss of natural cells based on a lifespan concept are presented. The lifespan indirect response (LIDR) models assume that cells (R) are produced at a constant rate (k(in)), survive during a certain duration T(R), and finally are ...
Pappu Vijay - - 2008
Three-dimensional computational modeling and simulation are presented on the adhesive rolling of deformable leukocytes over a P-selectin coated surface in parabolic shear flow in microchannels. The computational model is based on the immersed boundary method for cell deformation and Monte Carlo simulation for receptor/ligand interaction. The simulations are continued for ...
Eyiyurekli Manolya - - 2008
We present a computational model that successfully captures the cell behaviors that play important roles in 2-D cell aggregation. A virtual cell in our model is designed as an independent, discrete unit with a set of parameters and actions. Each cell is defined by its location, size, rates of chemoattractant ...
Leon-Quinto Trinidad - - 2009
This work presents a Biological Resource Bank generated as a complementary supporting tool for the reproduction and the in situ and ex situ conservation of the Iberian lynx. In its design we prioritized the preservation of a maximum of the current genetic and biological diversity of the population, and the ...
Causin, Paola; Mathematics, University ...
In the embryo, undifferentiated sets of cells form organized patterns following pathways marked by chemical cues, like ''Little Tom Thumbs'' of the molecular world. At this small scale, cues are represented by single molecules, displaced from their release location by diffusion. Diffusion is the movement of matter from areas with ...
Zhao Hongsheng - - 2008
A computer program, QtUCP, has been developed based on several well-established algorithms using GCC 4.0 and Qt 4.0 (Open Source Edition) under Debian GNU/Linux 4.0r0. It can determine the unit-cell parameters from an electron diffraction tilt series obtained from both double-tilt and rotation-tilt holders. In this approach, two or more ...
Féréol Sophie - - 2008
Cell mechanics provides an integrated view of many biological phenomena which are intimately related to cell structure and function. Because breathing constitutes a sustained motion synonymous with life, pulmonary cells are normally designed to support permanent cyclic stretch without breaking, while receiving mechanical cues from their environment. The authors study ...
Jin Songwan - - 2008
Diffusion through the extracellular space (ECS) in brain is important in drug delivery, intercellular communication, and extracellular ionic buffering. The ECS comprises approximately 20% of brain parenchymal volume and contains cell-cell gaps approximately 50 nm. We developed a random-walk model to simulate macromolecule diffusion in brain ECS in three dimensions ...
Rempe Michael J - - 2008
Since their inception, computational models have become increasingly complex and useful counterparts to laboratory experiments within the field of neuroscience. Today several software programs exist to solve the underlying mathematical system of equations, but such programs typically solve these equations in all parts of a cell (or network of cells) ...
Falou Omar - - 2008
High-frequency ultrasound is a novel method to detect cell death based on changes in cell morphology that cause alterations in the acoustic properties of cell ensembles in tissues. In previous work, our group has suggested that for cells with a nucleus to cell volume ratio of 0.33, the backscatter response ...
Wikström J - - 2008
BACKGROUND: In cell therapy, microencapsulated cells secrete therapeutic protein, which is further released from the microcapsules. In principle, some secreted, but unreleased, protein may accumulate in the microcapsules. The kinetic simulation model was built to simulate the potential accumulation of the protein in the microcapsules. METHODS: The alginate microcapsules were ...
Kolios Michael C - - 2008
The goal of ultrasonic tissue characterization is to extract information over and above the information conventionally displayed on imaging instruments which is typically the backscatter strength (B-mode image). The driving hypothesis of our work is that as the ultrasound wavelength approaches the size of a cell, the backscatter characteristics become ...
Gunji Yukio-Pegio - - 2008
A cell is a minimal self-sustaining system that can move and compute. Previous work has shown that a unicellular slime mold, Physarum, can be utilized as a biological computer based on cytoplasmic flow encapsulated by a membrane. Although the interplay between the modification of the boundary of a cell and ...
Korn R W - - 2008
OBJECTIVES: Extensive mathematical studies have been made on cell clone development but little has been advanced in the mathematics of small clone formation and virtually no actual data of small clone size has been collected. MATERIALS AND METHODS: Small clone sizes in leaf marginal cells of the aquatic plant Elodea ...
Nakajima Akihiko - - 2008
In multicellular organisms, several cell states coexist. For determining each cell type, cell-cell interactions are often essential, in addition to intracellular gene expression dynamics. Based on dynamical systems theory, we propose a mechanism for cell differentiation with regulation of populations of each cell type by taking simple cell models with ...
Hoffman A - - 2008
A previously described model for cellular proliferation, based on the relationship of the cell cycle to redox parameters, is explored here to account for the origin of the cancerous cell and some of its key abnormal characteristics, such as the Warburg effect, apoptosis, aneuploidy, and uncontrolled proliferation. We describe how ...
Regnault, Damien
Cellular automata have been mainly studied on very regular graphs carrying the cells (like lines or grids) and under synchronous dynamics (all cells update simultaneously). In this paper we study how the asynchronism and the topology of cells act upon the dynamics of the classical Minority rule. Beyond its apparent ...
Zhou, Jie
The demand for wireless mobile communications has grown at a very high rate, recently. In order to solve the non-uniform traffic rates, the use of cell splits is unavoidable for balancing the traffic rate and maximizing total system capacity. For cell planning, a DS-CDMA cellular system can be comprise of ...
Manbachi Amir - - 2008
Immobilization of cells inside microfluidic devices is a promising approach for enabling studies related to drug screening and cell biology. Despite extensive studies in using grooved substrates for immobilizing cells inside channels, a systematic study of the effects of various parameters that influence cell docking and retention within grooved substrates ...
Galle J - - 2009
Collective phenomena in multi-cellular assemblies can be approached on different levels of complexity. Here, we discuss a number of mathematical models which consider the dynamics of each individual cell, so-called agent-based or individual-based models (IBMs). As a special feature, these models allow to account for intracellular decision processes which are ...
Su, Jing
High-throughput cell culture is an emerging technology that shows promise as a tool for research in tissue engineering, drug discovery, and medical diagnostics. An important, but overlooked, challenge is the integration of experimental methods with information processing suitable for handling large databases of cell-cell and cell-substrate interactions. In this work ...
Franck Carl - - 2008
In cell culture, when cells are inoculated into fresh media, there can be a period of slow (or lag phase) growth followed by a transition to exponential growth. This period of slow growth is usually attributed to the cells' adaptation to a new environment. However, we argue that, based on ...
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