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Sample records for cellular parameters final

  1. Survey of cellular radiosensitivity parameters.

    PubMed

    Katz, R; Zachariah, R; Cucinotta, F A; Zhang, C

    1994-12-01

    A model of the formation of particle tracks in emulsion has been extended through the use of biological target theory to formulate a theory of the response of biological cells and molecules of biological importance to irradiation with energetic heavy ions. For this purpose the response to gamma rays is represented by the single-hit, multitarget model with parameters m and D0, while additional parameters kappa (or a0) and sigma 0 are required to represent the size of internal cellular targets and the effective cross-sectional area of the cell nucleus, respectively, for heavy-ion bombardments. For one-or-more-hit detectors, only the first three of these parameters are required and m = 1. For cells m is typically 2 or more. The model is developed from the concept that response to secondary electrons follows the same functional form for gamma rays and for the gamma rays surrounding an ion's path. Originally applied to dry enzymes and viruses in 1967, the model of the one-hit detector has been extended to emulsions, to other physical and chemical detectors, to single- and double-strand breaks in DNA in EO buffer and to three E. coli strains. The two-hit response has been observed for "track core" effects in radiation chemistry, for supralinearity in thermoluminescent dosimeters and for desensitized nuclear emulsions, where hit numbers up to 6 have been observed. In its extension to biological cells, additional concepts are required relating to the character of the track, namely the grain-count and track-width regimes, and to the ability of multitarget systems to acquire damage from intertrack delta rays (called gamma kill) as well as from intratrack delta rays (called ion kill). The model has been applied to some 40 sets of radiobiological data obtained from gamma, track-segment heavy-ion and neutron irradiations. Here we elaborate on the meaning of these concepts, tabulate the cellular parameters, and display their systematic behavior and the relationships among them

  2. Estimating cellular parameters through optimization procedures: elementary principles and applications.

    PubMed

    Kimura, Akatsuki; Celani, Antonio; Nagao, Hiromichi; Stasevich, Timothy; Nakamura, Kazuyuki

    2015-01-01

    Construction of quantitative models is a primary goal of quantitative biology, which aims to understand cellular and organismal phenomena in a quantitative manner. In this article, we introduce optimization procedures to search for parameters in a quantitative model that can reproduce experimental data. The aim of optimization is to minimize the sum of squared errors (SSE) in a prediction or to maximize likelihood. A (local) maximum of likelihood or (local) minimum of the SSE can efficiently be identified using gradient approaches. Addition of a stochastic process enables us to identify the global maximum/minimum without becoming trapped in local maxima/minima. Sampling approaches take advantage of increasing computational power to test numerous sets of parameters in order to determine the optimum set. By combining Bayesian inference with gradient or sampling approaches, we can estimate both the optimum parameters and the form of the likelihood function related to the parameters. Finally, we introduce four examples of research that utilize parameter optimization to obtain biological insights from quantified data: transcriptional regulation, bacterial chemotaxis, morphogenesis, and cell cycle regulation. With practical knowledge of parameter optimization, cell and developmental biologists can develop realistic models that reproduce their observations and thus, obtain mechanistic insights into phenomena of interest. PMID:25784880

  3. Estimating cellular parameters through optimization procedures: elementary principles and applications

    PubMed Central

    Kimura, Akatsuki; Celani, Antonio; Nagao, Hiromichi; Stasevich, Timothy; Nakamura, Kazuyuki

    2015-01-01

    Construction of quantitative models is a primary goal of quantitative biology, which aims to understand cellular and organismal phenomena in a quantitative manner. In this article, we introduce optimization procedures to search for parameters in a quantitative model that can reproduce experimental data. The aim of optimization is to minimize the sum of squared errors (SSE) in a prediction or to maximize likelihood. A (local) maximum of likelihood or (local) minimum of the SSE can efficiently be identified using gradient approaches. Addition of a stochastic process enables us to identify the global maximum/minimum without becoming trapped in local maxima/minima. Sampling approaches take advantage of increasing computational power to test numerous sets of parameters in order to determine the optimum set. By combining Bayesian inference with gradient or sampling approaches, we can estimate both the optimum parameters and the form of the likelihood function related to the parameters. Finally, we introduce four examples of research that utilize parameter optimization to obtain biological insights from quantified data: transcriptional regulation, bacterial chemotaxis, morphogenesis, and cell cycle regulation. With practical knowledge of parameter optimization, cell and developmental biologists can develop realistic models that reproduce their observations and thus, obtain mechanistic insights into phenomena of interest. PMID:25784880

  4. Parameter-less approaches for interpreting dynamic cellular response

    PubMed Central

    2014-01-01

    Cellular response such as cell signaling is an integral part of information processing in biology. Upon receptor stimulation, numerous intracellular molecules are invoked to trigger the transcription of genes for specific biological purposes, such as growth, differentiation, apoptosis or immune response. How complex are such specialized and sophisticated machinery? Computational modeling is an important tool for investigating dynamic cellular behaviors. Here, I focus on certain types of key signaling pathways that can be interpreted well using simple physical rules based on Boolean logic and linear superposition of response terms. From the examples shown, it is conceivable that for small-scale network modeling, reaction topology, rather than parameter values, is crucial for understanding population-wide cellular behaviors. For large-scale response, non-parametric statistical approaches have proven valuable for revealing emergent properties. PMID:25183996

  5. EFFECTS OF SELECTED ASBESTOS FIBERS ON CELLULAR AND MOLECULAR PARAMETERS

    EPA Science Inventory

    Embryonic cultures were used to compare the effects of five asbestos materials on a cellular, biochemical and molecular basis. Chrysotile was found to be the most cytotoxic followed by crocidolite, tremolite, amosite, and silica. Results of tests involving cellular ratios of cycl...

  6. EFFECTS OF SELECTED WATERBORNE PARTICULATES ON CELLULAR AND MOLECULAR PARAMETERS

    EPA Science Inventory

    Embryonic cultures were used to compare the effects of six particulate samples, some filtered directly from drinking water on a cellular, biochemical and molecular basis. Cytotoxicity was exhibited in human cells for all agents tested at the highest concentration used (10 mg/ml)....

  7. Effect of hyperthermic water bath on parameters of cellular immunity.

    PubMed

    Blazícková, S; Rovenský, J; Koska, J; Vigas, M

    2000-01-01

    Effects of hyperthermic water bath on selected immune parameters (lymphocyte subpopulations, natural killer (NK) cell counts and their activity) were studied in a group of 10 volunteers. Application of hyperthermic water bath (both topical and whole-body) was followed by a significant reduction of relative B lymphocyte counts. Whole-body hyperthermic water bath reduced relative total T lymphocyte counts, increased relative CD8+ T lymphocyte and NK cell counts and increased NK activity. Whole-body hyperthermic bath increased somatotropic hormone (STH) activity in eight out of 10 volunteers; higher relative counts of CD8+ lymphocytes and NK cells were observed compared with the group of volunteers not responding to hyperthermic water bath by STH secretion. In five volunteers STH was released in response to local hyperthermic water bath and the NK activity of lymphocytes also increased but their relative counts did not. The results suggest that these increases in CD8+ lymphocyte and NK cell counts are probably dependent on increased STH production. PMID:11146901

  8. Cellular electrical micro-impedance parameter artifacts produced by passive and active current regulation.

    PubMed

    English, Anthony E; Squire, James C; Moy, Alan B

    2008-03-01

    This study analyzes the cellular microelectrode voltage measurement errors produced by active and passive current regulation, and the propagation of these errors into cellular barrier function parameter estimates. The propagation of random and systematic errors into these parameters is accounted for within a Riemannian manifold framework consistent with information geometry. As a result, the full non-linearity of the model parameter state dependence, the instrumental noise distribution, and the systematic errors associated with the voltage to impedance conversion, are accounted for. Specifically, cellular model parameters are treated as the coordinates of a model space manifold that inherits a Riemannian metric from the data space. The model space metric is defined in terms of the pull back of an instrumental noise-dependent Fisher information metric. Additional noise sources produced by the evaluation of the cell-covered electrode model that is a function of a naked electrode random variable are also included in the analysis. Based on a circular cellular micro-impedance model in widespread use, this study shows that cellular barrier function parameter estimates are highly model state dependent. Systematic errors produced by coaxial lead capacitances and circuit loading can also lead to significant and model state-dependent parameter errors and should, therefore, be either reduced or corrected for analytically. PMID:18202917

  9. Evolving cellular automata to perform computations. Final technical report

    SciTech Connect

    Crutchfield, J.P.; Mitchell, M.

    1998-04-01

    The overall goals of the project are to determine the usefulness of genetic algorithms (GAs) in designing spatially extended parallel systems to perform computational tasks and to develop theoretical frameworks both for understanding the computation in the systems evolved by the GA and for understanding the evolutionary process which successful systems are designed. In the original proposal the authors scheduled the first year of the project to be devoted to experimental grounding. During the first year they developed the simulation and graphics software necessary for doing experiments and analysis on one dimensional cellular automata (CAs), and they performed extensive experiments and analysis concerning two computational tasks--density classification and synchronization. Details of these experiments and results, and a list of resulting publications, were given in the 1994--1995 report. The authors scheduled the second year to be devoted to theoretical development. (A third year, to be funded by the National Science Foundation, will be devoted to applications.) Accordingly, most of the effort during the second year was spent on theory, both of GAs and of the CAs that they evolve. A central notion is that of the computational strategy of a CA, which they formalize in terms of domains, particles, and particle interactions. This formalization builds on the computational mechanics framework developed by Crutchfield and Hanson for understanding intrinsic computation in spatially extended dynamical systems. They have made significant progress in the following areas: (1) statistical dynamics of GAs; (2) formalizing particle based computation in cellular automata; and (3) computation in two-dimensional CAs.

  10. Cellular automata for traffic flow modeling. Final report

    SciTech Connect

    Benjaafar, S.; Dooley, K.; Setyawan, W.

    1997-12-01

    In this paper, the authors explore the usefulness of cellular automata to traffic flow modeling. The authors extend some of the existing CA models to capture characteristics of traffic flow that have not been possible to model using either conventional analytical models or existing simulation techniques. In particular, the authors examine higher moments of traffic flow and evaluate their effect on overall traffic performance. The behavior of these higher moments is found to be surprising, somewhat counter-intuitive, and to have important implications for design and control of traffic systems. For example, the authors show that the density of maximum throughput is near the density of maximum speed variance. Contrary to current practice, traffic should, therefore, be steered away from this density region. For deterministic systems the authors found traffic flow to possess a finite period which is highly sensitive to density in a non-monotonic fashion. The authors show that knowledge of this periodic behavior to be very useful in designing and controlling automated systems. These results are obtained for both single and two lane systems. For two lane systems, the authors also examine the relationship between lane changing behavior and flow performance. The authors show that the density of maximum land changing frequency occurs past the density of maximum throughput. Therefore, traffic should also be steered away from this density region.

  11. Parameters and characteristics governing cellular internalization and trans-barrier trafficking of nanostructures

    PubMed Central

    Murugan, Karmani; Choonara, Yahya E; Kumar, Pradeep; Bijukumar, Divya; du Toit, Lisa C; Pillay, Viness

    2015-01-01

    Cellular internalization and trans-barrier transport of nanoparticles can be manipulated on the basis of the physicochemical and mechanical characteristics of nanoparticles. Research has shown that these factors significantly influence the uptake of nanoparticles. Dictating these characteristics allows for the control of the rate and extent of cellular uptake, as well as delivering the drug-loaded nanosystem intra-cellularly, which is imperative for drugs that require a specific cellular level to exert their effects. Additionally, physicochemical characteristics of the nanoparticles should be optimal for the nanosystem to bypass the natural restricting phenomena of the body and act therapeutically at the targeted site. The factors at the focal point of emerging smart nanomedicines include nanoparticle size, surface charge, shape, hydrophobicity, surface chemistry, and even protein and ligand conjugates. Hence, this review discusses the mechanism of internalization of nanoparticles and ideal nanoparticle characteristics that allow them to evade the biological barriers in order to achieve optimal cellular uptake in different organ systems. Identifying these parameters assists with the progression of nanomedicine as an outstanding vector of pharmaceuticals. PMID:25834433

  12. Cellular and subcellular oxidative stress parameters following severe spinal cord injury

    PubMed Central

    Visavadiya, Nishant P.; Patel, Samir P.; VanRooyen, Jenna L.; Sullivan, Patrick G.; Rabchevsky, Alexander G.

    2015-01-01

    The present study undertook a comprehensive assessment of the acute biochemical oxidative stress parameters in both cellular and, notably, mitochondrial isolates following severe upper lumbar contusion spinal cord injury (SCI) in adult female Sprague Dawley rats. At 24 h post-injury, spinal cord tissue homogenate and mitochondrial fractions were isolated concurrently and assessed for glutathione (GSH) content and production of nitric oxide (NO•), in addition to the presence of oxidative stress markers 3-nitrotyrosine (3-NT), protein carbonyl (PC), 4-hydroxynonenal (4-HNE) and lipid peroxidation (LPO). Moreover, we assessed production of superoxide (O2•-) and hydrogen peroxide (H2O2) in mitochondrial fractions. Quantitative biochemical analyses showed that compared to sham, SCI significantly lowered GSH content accompanied by increased NO• production in both cellular and mitochondrial fractions. SCI also resulted in increased O2•- and H2O2 levels in mitochondrial fractions. Western blot analysis further showed that reactive oxygen/nitrogen species (ROS/RNS) mediated PC and 3-NT production were significantly higher in both fractions after SCI. Conversely, neither 4-HNE levels nor LPO formation were increased at 24 h after injury in either tissue homogenate or mitochondrial fractions. These results indicate that by 24 h post-injury ROS-induced protein oxidation is more prominent compared to lipid oxidation, indicating a critical temporal distinction in secondary pathophysiology that is critical in designing therapeutic approaches to mitigate consequences of oxidative stress. PMID:26760911

  13. Cellular and subcellular oxidative stress parameters following severe spinal cord injury.

    PubMed

    Visavadiya, Nishant P; Patel, Samir P; VanRooyen, Jenna L; Sullivan, Patrick G; Rabchevsky, Alexander G

    2016-08-01

    The present study undertook a comprehensive assessment of the acute biochemical oxidative stress parameters in both cellular and, notably, mitochondrial isolates following severe upper lumbar contusion spinal cord injury (SCI) in adult female Sprague Dawley rats. At 24h post-injury, spinal cord tissue homogenate and mitochondrial fractions were isolated concurrently and assessed for glutathione (GSH) content and production of nitric oxide (NO(•)), in addition to the presence of oxidative stress markers 3-nitrotyrosine (3-NT), protein carbonyl (PC), 4-hydroxynonenal (4-HNE) and lipid peroxidation (LPO). Moreover, we assessed production of superoxide (O2(•-)) and hydrogen peroxide (H2O2) in mitochondrial fractions. Quantitative biochemical analyses showed that compared to sham, SCI significantly lowered GSH content accompanied by increased NO(•) production in both cellular and mitochondrial fractions. SCI also resulted in increased O2(•-) and H2O2 levels in mitochondrial fractions. Western blot analysis further showed that reactive oxygen/nitrogen species (ROS/RNS) mediated PC and 3-NT production were significantly higher in both fractions after SCI. Conversely, neither 4-HNE levels nor LPO formation were increased at 24h after injury in either tissue homogenate or mitochondrial fractions. These results indicate that by 24h post-injury ROS-induced protein oxidation is more prominent compared to lipid oxidation, indicating a critical temporal distinction in secondary pathophysiology that is critical in designing therapeutic approaches to mitigate consequences of oxidative stress. PMID:26760911

  14. Cellular scanning strategy for selective laser melting: Generating reliable, optimized scanning paths and processing parameters

    NASA Astrophysics Data System (ADS)

    Mohanty, Sankhya; Hattel, Jesper H.

    2015-03-01

    Selective laser melting is yet to become a standardized industrial manufacturing technique. The process continues to suffer from defects such as distortions, residual stresses, localized deformations and warpage caused primarily due to the localized heating, rapid cooling and high temperature gradients that occur during the process. While process monitoring and control of selective laser melting is an active area of research, establishing the reliability and robustness of the process still remains a challenge. In this paper, a methodology for generating reliable, optimized scanning paths and process parameters for selective laser melting of a standard sample is introduced. The processing of the sample is simulated by sequentially coupling a calibrated 3D pseudo-analytical thermal model with a 3D finite element mechanical model. The optimized processing parameters are subjected to a Monte Carlo method based uncertainty and reliability analysis. The reliability of the scanning paths are established using cumulative probability distribution functions for process output criteria such as sample density, thermal homogeneity, etc. A customized genetic algorithm is used along with the simulation model to generate optimized cellular scanning strategies and processing parameters, with an objective of reducing thermal asymmetries and mechanical deformations. The optimized scanning strategies are used for selective laser melting of the standard samples, and experimental and numerical results are compared.

  15. Simultaneous model discrimination and parameter estimation in dynamic models of cellular systems

    PubMed Central

    2013-01-01

    Background Model development is a key task in systems biology, which typically starts from an initial model candidate and, involving an iterative cycle of hypotheses-driven model modifications, leads to new experimentation and subsequent model identification steps. The final product of this cycle is a satisfactory refined model of the biological phenomena under study. During such iterative model development, researchers frequently propose a set of model candidates from which the best alternative must be selected. Here we consider this problem of model selection and formulate it as a simultaneous model selection and parameter identification problem. More precisely, we consider a general mixed-integer nonlinear programming (MINLP) formulation for model selection and identification, with emphasis on dynamic models consisting of sets of either ODEs (ordinary differential equations) or DAEs (differential algebraic equations). Results We solved the MINLP formulation for model selection and identification using an algorithm based on Scatter Search (SS). We illustrate the capabilities and efficiency of the proposed strategy with a case study considering the KdpD/KdpE system regulating potassium homeostasis in Escherichia coli. The proposed approach resulted in a final model that presents a better fit to the in silico generated experimental data. Conclusions The presented MINLP-based optimization approach for nested-model selection and identification is a powerful methodology for model development in systems biology. This strategy can be used to perform model selection and parameter estimation in one single step, thus greatly reducing the number of experiments and computations of traditional modeling approaches. PMID:23938131

  16. NK cell tolerance as the final endorsement of prenatal tolerance after in utero hematopoietic cellular transplantation

    PubMed Central

    Alhajjat, Amir M.; Lee, Amanda E.; Strong, Beverly S.; Shaaban, Aimen F.

    2015-01-01

    The primary benefits of in utero hematopoietic cellular transplantation (IUHCT) arise from transplanting curative cells prior to the immunologic maturation of the fetus. However, this approach has been routinely successful only in the treatment of congenital immunodeficiency diseases that include an inherent NK cell deficiency despite the existence of normal maternal immunity in either setting. These observations raise the possibility that fetal NK cells function as an early barrier to allogeneic IUHCT. Herein, we summarize the findings of previous studies of prenatal NK cell allospecific tolerance in mice and in humans. Cumulatively, this new information reveals the complexity of the fetal immune response in the setting of rejection or tolerance and illustrates the role for fetal NK cells in the final endorsement of allospecific prenatal tolerance. PMID:25852555

  17. Trabecular bone structural parameters evaluated using dental cone-beam computed tomography: cellular synthetic bones

    PubMed Central

    2013-01-01

    Objective This study compared the adequacy of dental cone beam computed tomography (CBCT) and micro computed tomography (micro-CT) in evaluating the structural parameters of trabecular bones. Methods The cellular synthetic bones in 4 density groups (Groups 1–4: 0.12, 0.16, 0.20, and 0.32 g/cm3) were used in this study. Each group comprised 8 experimental specimens that were approximately 1 cm3. Dental CBCT and micro-CT scans were conducted on each specimen to obtain independent measurements of the following 4 trabecular bone structural parameters: bone volume fraction (BV/TV), specific bone surface (BS/BV), trabecular thickness (Tb.Th.), and trabecular separation (Tb.Sp.). Wilcoxon signed ranks tests were used to compare the measurement variations between the dental CBCT and micro-CT scans. A Spearman analysis was conducted to calculate the correlation coefficients (r) of the dental CBCT and micro-CT measurements. Results and Conclusion Of the 4 groups, the BV/TV and Tb.Th. measured using dental CBCT were larger compared with those measured using micro-CT. By contrast, the BS/BV measured using dental CBCT was significantly less compared with those measured using micro-CT. Furthermore, in the low-density groups (Groups 1 and 2), the Tb.Sp. measured using dental CBCT was smaller compared with those measured using micro-CT. However, the Tb.Sp. measured using dental CBCT was slightly larger in the high-density groups (Groups 3 and 4) than it was in the low density groups. The correlation coefficients between the BV/TV, BS/BV, Tb.Th., and Tb.Sp. values measured using dental CBCT and micro-CT were 0.9296 (p < .001), 0.8061 (p < .001), 0.9390 (p < .001), and 0.9583 (p < .001), respectively. Although the dental CBCT and micro-CT approaches exhibited high correlations, the absolute values of BV/TV, BS/BV, Tb.Th., Tb.Sp. differed significantly between these measurements. Additional studies must be conducted to evaluate using dental CBCT in clinical practice. PMID

  18. ESTIM: A parameter estimation computer program: Final report

    SciTech Connect

    Hills, R.G.

    1987-08-01

    The computer code, ESTIM, enables subroutine versions of existing simulation codes to be used to estimate model parameters. Nonlinear least squares techniques are used to find the parameter values that result in a best fit between measurements made in the simulation domain and the simulation code's prediction of these measurements. ESTIM utilizes the non-linear least square code DQED (Hanson and Krogh (1982)) to handle the optimization aspects of the estimation problem. In addition to providing weighted least squares estimates, ESTIM provides a propagation of variance analysis. A subroutine version of COYOTE (Gartling (1982)) is provided. The use of ESTIM with COYOTE allows one to estimate the thermal property model parameters that result in the best agreement (in a least squares sense) between internal temperature measurements and COYOTE's predictions of these internal temperature measurements. We demonstrate the use of ESTIM through several example problems which utilize the subroutine version of COYOTE.

  19. Engineering parameters for environmental remediation technologies. Final report

    SciTech Connect

    Kikkeri, S.R.

    1996-06-01

    This document identifies engineering parameters and establishes ranges of values for 33 environmental remediation technologies. The main purpose is to provide U.S. Coast Guard (USCG) civil engineering personnel with summarized information regarding matrix characteristics and design parameters that are applicable to each of the technologies. This information is intended to guide USCG personnel when making decisions regarding the selection of appropriate remediation technologies. This document has been developed to be used as a companion document to the Remediation Technologies Screening Matrix and Reference Guide (EPN542/B-94/013).

  20. On a three-parameter quantum battle of the sexes cellular automaton

    NASA Astrophysics Data System (ADS)

    Alonso-Sanz, Ramón

    2013-05-01

    The dynamics of a spatial quantum formulation of the iterated battle of the sexes game is studied in this work. The game is played in the cellular automata manner, i.e., with local and synchronous interaction. The effect of spatial structure is assessed when allowing the players to adopt quantum strategies that are no restricted to any particular subset of the possible strategies.

  1. Real time kinetic flow cytometry measurements of cellular parameter changes evoked by nanosecond pulsed electric field.

    PubMed

    Orbán, Csaba; Pérez-García, Esther; Bajnok, Anna; McBean, Gethin; Toldi, Gergely; Blanco-Fernandez, Alfonso

    2016-05-01

    Nanosecond pulsed electric field (nsPEF) is a novel method to increase cell proliferation rate. The phenomenon is based on the microporation of cellular organelles and membranes. However, we have limited information on the effects of nsPEF on cell physiology. Several studies have attempted to describe the effects of this process, however no real time measurements have been conducted to date. In this study we designed a model system which allows the measurement of cellular processes before, during and after nsPEF treatment in real time. The system employs a Vabrema Mitoplicator(TM) nsPEF field generating instrument connected to a BD Accuri C6 cytometer with a silicon tube led through a peristaltic pump. This model system was applied to observe the effects of nsPEF in mammalian C6 glioblastoma (C6 glioma) and HEK-293 cell lines. Viability (using DRAQ7 dye), intracellular calcium levels (using Fluo-4 dye) and scatter characteristics were measured in a kinetic manner. Data were analyzed using the FACSKin software. The viability and morphology of the investigated cells was not altered upon nsPEF treatment. The response of HEK-293 cells to ionomycin as positive control was significantly lower in the nsPEF treated samples compared to non-treated cells. This difference was not observed in C6 cells. FSC and SSC values were not altered significantly by the nsPEF treatment. Our results indicate that this model system is capable of reliably investigating the effects of nsPEF on cellular processes in real time. © 2016 International Society for Advancement of Cytometry. PMID:26990601

  2. Non-ambiguous recovery of Biot poroelastic parameters of cellular panels using ultrasonicwaves

    NASA Astrophysics Data System (ADS)

    Ogam, Erick; Fellah, Z. E. A.; Sebaa, Naima; Groby, J.-P.

    2011-03-01

    The inverse problem of the recovery of the poroelastic parameters of open-cell soft plastic foam panels is solved by employing transmitted ultrasonic waves (USW) and the Biot-Johnson-Koplik-Champoux-Allard (BJKCA) model. It is shown by constructing the objective functional given by the total square of the difference between predictions from the BJKCA interaction model and experimental data obtained with transmitted USW that the inverse problem is ill-posed, since the functional exhibits several local minima and maxima. In order to solve this problem, which is beyond the capability of most off-the-shelf iterative nonlinear least squares optimization algorithms (such as the Levenberg Marquadt or Nelder-Mead simplex methods), simple strategies are developed. The recovered acoustic parameters are compared with those obtained using simpler interaction models and a method employing asymptotic phase velocity of the transmitted USW. The retrieved elastic moduli are validated by solving an inverse vibration spectroscopy problem with data obtained from beam-like specimens cut from the panels using an equivalent solid elastodynamic model as estimator. The phase velocities are reconstructed using computed, measured resonance frequencies and a time-frequency decomposition of transient waves induced in the beam specimen. These confirm that the elastic parameters recovered using vibration are valid over the frequency range ofstudy.

  3. Effects of 60-day bed rest with and without exercise on cellular and humoral immunological parameters.

    PubMed

    Hoff, Paula; Belavý, Daniel L; Huscher, Dörte; Lang, Annemarie; Hahne, Martin; Kuhlmey, Anne-Kathrin; Maschmeyer, Patrick; Armbrecht, Gabriele; Fitzner, Rudolf; Perschel, Frank H; Gaber, Timo; Burmester, Gerd-Rüdiger; Straub, Rainer H; Felsenberg, Dieter; Buttgereit, Frank

    2015-07-01

    Exercise at regular intervals is assumed to have a positive effect on immune functions. Conversely, after spaceflight and under simulated weightlessness (e.g., bed rest), immune functions can be suppressed. We aimed to assess the effects of simulated weightlessness (Second Berlin BedRest Study; BBR2-2) on immunological parameters and to investigate the effect of exercise (resistive exercise with and without vibration) on these changes. Twenty-four physically and mentally healthy male volunteers (20-45 years) performed resistive vibration exercise (n=7), resistance exercise without vibration (n=8) or no exercise (n=9) within 60 days of bed rest. Blood samples were taken 2 days before bed rest, on days 19 and 60 of bed rest. Composition of immune cells was analyzed by flow cytometry. Cytokines and neuroendocrine parameters were analyzed by Luminex technology and ELISA/RIA in plasma. General changes over time were identified by paired t-test, and exercise-dependent effects by pairwise repeated measurements (analysis of variance (ANOVA)). With all subjects pooled, the number of granulocytes, natural killer T cells, hematopoietic stem cells and CD45RA and CD25 co-expressing T cells increased and the number of monocytes decreased significantly during the study; the concentration of eotaxin decreased significantly. Different impacts of exercise were seen for lymphocytes, B cells, especially the IgD(+) subpopulation of B cells and the concentrations of IP-10, RANTES and DHEA-S. We conclude that prolonged bed rest significantly impacts immune cell populations and cytokine concentrations. Exercise was able to specifically influence different immunological parameters. In summary, our data fit the hypothesis of immunoprotection by exercise and may point toward even superior effects by resistive vibration exercise. PMID:25382740

  4. Effects of 60-day bed rest with and without exercise on cellular and humoral immunological parameters

    PubMed Central

    Hoff, Paula; Belavý, Daniel L; Huscher, Dörte; Lang, Annemarie; Hahne, Martin; Kuhlmey, Anne-Kathrin; Maschmeyer, Patrick; Armbrecht, Gabriele; Fitzner, Rudolf; Perschel, Frank H; Gaber, Timo; Burmester, Gerd-Rüdiger; Straub, Rainer H; Felsenberg, Dieter; Buttgereit, Frank

    2015-01-01

    Exercise at regular intervals is assumed to have a positive effect on immune functions. Conversely, after spaceflight and under simulated weightlessness (e.g., bed rest), immune functions can be suppressed. We aimed to assess the effects of simulated weightlessness (Second Berlin BedRest Study; BBR2-2) on immunological parameters and to investigate the effect of exercise (resistive exercise with and without vibration) on these changes. Twenty-four physically and mentally healthy male volunteers (20–45 years) performed resistive vibration exercise (n=7), resistance exercise without vibration (n=8) or no exercise (n=9) within 60 days of bed rest. Blood samples were taken 2 days before bed rest, on days 19 and 60 of bed rest. Composition of immune cells was analyzed by flow cytometry. Cytokines and neuroendocrine parameters were analyzed by Luminex technology and ELISA/RIA in plasma. General changes over time were identified by paired t-test, and exercise-dependent effects by pairwise repeated measurements (analysis of variance (ANOVA)). With all subjects pooled, the number of granulocytes, natural killer T cells, hematopoietic stem cells and CD45RA and CD25 co-expressing T cells increased and the number of monocytes decreased significantly during the study; the concentration of eotaxin decreased significantly. Different impacts of exercise were seen for lymphocytes, B cells, especially the IgD+ subpopulation of B cells and the concentrations of IP-10, RANTES and DHEA-S. We conclude that prolonged bed rest significantly impacts immune cell populations and cytokine concentrations. Exercise was able to specifically influence different immunological parameters. In summary, our data fit the hypothesis of immunoprotection by exercise and may point toward even superior effects by resistive vibration exercise. PMID:25382740

  5. Advanced Cellular and Biomolecular Imaging at Lehigh University, (PA) Final Scientific/Technical Report

    SciTech Connect

    Cassimeris, Lynne, U.

    2010-09-10

    Lehigh University is establishing an interdisciplinary program in high resolution cellular and subcellular biological imaging for a range of applications including improved cancer detection. The completed DOE project added to Lehigh?s bio-imaging infrastructure through acquisition of a new confocal microscope system as well as upgrades to two pieces of existing equipment. Bio-imaging related research at Lehigh was also supported through two seed grants for initiation of new projects.

  6. Cellular Response upon Stress: p57 Contribution to the Final Outcome

    PubMed Central

    Rossi, Marianna Nicoletta; Antonangeli, Fabrizio

    2015-01-01

    Progression through the cell cycle is one of the most important decisions during the life of a cell and several kinds of stress are able to influence this choice. p57 is a cyclin-dependent kinase inhibitor belonging to the CIP/KIP family and is a well-known regulator of the cell cycle during embryogenesis and tissue differentiation. p57 loss has been reported in a variety of cancers and great effort has been spent during the past years studying the mechanisms of p57 regulation and the effects of p57 reexpression on tumor growth. Recently, growing amount of evidence points out that p57 has a specific function in cell cycle regulation upon cellular stress that is only partially shared by the other CIP/KIP inhibitors p21 and p27. Furthermore, it is nowadays emerging that p57 plays a role in the induction of apoptosis and senescence after cellular stress independently of its cell cycle related functions. This review focuses on the contribution that p57 holds in regulating cell cycle arrest, apoptosis, and senescence after cellular stress with particular attention to the response of cancer cells. PMID:26491224

  7. Experimental study on detonation parameters and cellular structures of fuel cloud

    NASA Astrophysics Data System (ADS)

    Xie, Li-Feng; Li, Bin; Zhang, Yu-Lei

    2012-04-01

    In this paper, detonation parameters of fuel cloud, such as propylene oxide (PO), isopropyl nitrate (IPN), hexane, 90# oil and decane were measured in a self-designed and constructed vertical shock tube. Results show that the detonation pressure and velocity of PO increase to a peak value and then decrease smoothly with increasing equivalence ratio. Several nitrate sensitizers were added into PO to make fuel mixtures, and test results indicated that the additives can efficiently enhance detonation velocity and pressure of fuel cloud and one type of additive n-propyl nitrate (NPN) played the best in the improvement. The critical initiation energy that directly initiated detonation of all the test liquid fuel clouds showed a U-shape curve relationship with equivalence ratios. The optimum concentration lies on the rich-fuel side ( ϕ > 1). The critical initiation energy is closely related to molecular structure and volatility of fuels. IPN and PO have similar critical values while that of alkanes are larger. Detonation cell sizes of PO were respectively investigated at 25°C, 35°C and 50°C with smoked foil technique. The cell width shows a U-shape curve relationship with equivalence ratios at all temperatures. The minimal cell width also lies on the rich-fuel side ( ϕ > 1). The cell width of PO vapor is slightly larger than that of PO cloud. Therefore, the detonation reaction of PO at normal temperature is controlled by gas phase reaction.

  8. Effects of cellular parameters on the in vitro osteogenic potential of dual-gelling mesenchymal stem cell-laden hydrogels.

    PubMed

    Vo, Tiffany N; Tabata, Yasuhiko; Mikos, Antonios G

    2016-08-01

    This work investigated the effects of cellular encapsulation density and differentiation stage on the osteogenic capacity of injectable, dual physically and chemically gelling hydrogels comprised of thermogelling macromers and polyamidoamine crosslinkers. Undifferentiated and osteogenically predifferentiated mesenchymal stem cells (MSCs) were encapsulated within 20 wt% composite hydrogels with gelatin microparticles at densities of six or 15 million cells/mL. We hypothesized that a high encapsulation density and predifferentiation would promote increased cellular interaction and accelerate osteogenesis, leading to enhanced osteogenic potential in vitro. Hydrogels were able to maintain the viability of the encapsulated cells over a period of 28 days, with the high encapsulation density and predifferentiation group possessing the highest DNA content at all time points. Early alkaline phosphatase activity and mineralization were promoted by encapsulation density, whereas this effect by predifferentiation was only observed in the low seeding density groups. Both parameters only demonstrated short-lived effects when examined independently, but jointly led to greater levels of alkaline phosphatase activity and mineralization. The combined effects suggest that there may be optimal encapsulation densities and differentiation periods that need to be investigated to improve MSCs for biomaterial-based therapeutics in bone tissue engineering. PMID:27328947

  9. [Assessment of selected parameters of non-specific cellular response in patients with tick borne encephalitis (TBE)].

    PubMed

    Izycka, A; Jabłońska, E; Zajkowska, J; Hermanowska-Szpakowicz, T; Izycki, T

    2000-01-01

    The aim of this study was the assessment of certain PMN functions involving migration, chemotaxis, phagocytic activity and intracellular oxygen-dependent killing in patients with TBE. The examination involved 47 persons treated in the Department of Infectious and Neuroinfectious Diseases Medical Academy in Białystok. Two examinations were done: before and just after treatment. Control group contained 29 healthy persons. Migration and chemotaxis were assessed by agarose method of Nelson and al. and Glaser and al. Phagocytic activity was examined by microscopic method and intracellular oxygen-dependent killing by reduction test of NBT by Parks method. Analysis of results showed a decrease of all examined parameters both before and after treatment. It indicates a depression of non-specific cellular response in patients with Lyme meningoencephalitis. PMID:11105301

  10. Biological (molecular and cellular) markers of toxicity. Final report, September 15, 1988--September 14, 1991

    SciTech Connect

    Shugart, L.R.; D`Surney, S.J.; Gettys-Hull, C.; Greeley, M.S. Jr.

    1991-12-15

    Several molecular and cellular markers of genotoxicity were adapted for measurement in the Medaka (Oryzias latipes), and were used to describe the effects of treatment of the organism with diethylnitrosamine (DEN). NO{sup 6}-ethyl guanine adducts were detected, and a slight statistically significant, increase in DNA strand breaks was observed. These results are consistent with the hypothesis that prolonged exposure to high levels of DEN induced alkyltransferase activity which enzymatically removes any O{sup 6}-ethyl guanine adducts but does not result in strand breaks or hypomethylation of the DNA such as might be expected from excision repair of chemically modified DNA. Following a five week continuous DEN exposure with 100 percent renewal of DEN-water every third day, the F values (DNA double strandedness) increased considerably and to similar extent in fish exposed to 25, 50, and 100 ppM DEN. This has been observed also in medaka exposed to BaP.

  11. Cellular energy metabolism. Final technical report, May 1, 1987--April 30, 1991

    SciTech Connect

    Glaser, M.

    1991-06-01

    Studies have been carried out on adenylate kinase which is an important enzyme in determining the concentrations of the adenine nucleotides. An efficient method has been developed to clone mutant adenylate kinase genes in E. coli. Site-specific mutagenesis of the wild type gene also has been used to obtain forms of adenylate kinase with altered amino acids. The wild type and mutant forms of adenylate kinase have been overexpressed and large quantities were readily isolated. The kinetic and fluorescence properties of the different forms of adenylate kinase were characterized. This has led to a new model for the location of the AMP and ATP bindings sites on the enzyme and a proposal for the mechanism of substrate inhibition. Crystals of the wild type enzyme were obtained that diffract to at least 2.3 {angstrom} resolution. Experiments were also initiated to determine the function of adenylate kinase in vivo. In one set of experiments, E. coli strains with mutations in adenylate kinase showed large changes in cellular nucleotides after reaching the stationary phase in a low phosphate medium. This was caused by selective proteolytic degradation of the mutant adenylate kinase caused by phosphate starvation.

  12. Investigations of cellular parameters to establish the response of a biomodulator: galactoside-specific Lectin from Viscum album plant extract.

    PubMed

    Hajto, T; Hostanska, K; Fischer, J; Lentzen, H

    1996-09-01

    Injections of non-toxic doses of purified galactoside-specific lectin from the Viscum album plant (VAA-I) caused significant changes in the cellular host defense system in animal models. To establish the immunomodulatory potency of VAA-I on human subjects, four randomized double blind crossover trials were performed on healthy volunteers. In the first and second trials using either older (storage over 8 months at 4°C) or freshly (application immediately after production) isolated lectin enriched preparation from mistletoe extract by ultrafiltration with known VAA-I content, the effect of lectin on the number of CD 3+, CD4+, CD 8+, CD 16+/56+ cells, natural killer cytotoxicity and frequency of large granular lymphocytes was tested in peripheral blood of nine and eight individuals, respectively. In comparison to the significant increase in the number of peripheral lymphocytes observed in balb/c mice, human healthy individuals showed no significant difference between their responses after lectin enriched preparation and saline treatment. Due the considerable intrinsic fluctuation of these parameters in placebo control and the assumption that a change in immunomodulatory potency of VAA-I in lectin enriched preparation depends on aging, a third and fourth double blind trial, in this case using freshly isolated VAA-I from plant, were performed on six and eight healthy volunteers, respectively. In these studies an other more rapidly detectable parameter, the priming of polymorphonuclear (PMN) leukocytes, was monitored. In both studies, 5 h after lectin injection, significant enhancement in priming of circulating PMNs was found compared to the placebo response. PMID:23194960

  13. Towards a cellular multi-parameter analysis platform: fluorescence in situ hybridization (FISH) on microhole-array chips.

    PubMed

    Kurz, Christian M; Moosdijk, Stefan V D; Thielecke, Hagen; Velten, Thomas

    2011-01-01

    Highly-sensitive analysis systems based on cellular multi-parameter are needed in the diagnostics. Therefore we improved our previously developed chip platform for another additional analysis method, the fluorescence in situ hybridization. Fluorescence in situ hybridization (FISH) is a technique used in the diagnostics to determine the localization and the presence or absence of specific DNA sequence. To improve this labor- and cost-intensive method, we reduced the assay consumption by a factor of 5 compared to the standard protocol. Microhole chips were used for making the cells well addressable. The chips were fabricated by semiconductor technology on the basis of a Silicon wafer with a thin deposited silicon nitride layer (Si(3)N(4)). Human retina pigment epithelia (ARPE-19) cells were arrayed on 5-μm holes of a 35 × 35 microhole-array by a gently negative differential pressure of around 5 mbar. After 3 hours of incubation the cells were attached to the chip and the FISH protocol was applied to the positioned cells. A LabView software was developed to simplify the analysis. The software automatically counts the number of dots (positive labeled chromosome regions) as well as the distance between adjacent dots. Our developed platform reduces the assay consumption and the labor time. Furthermore, during the 3 hours of incubation non-invasive or minimal-invasive methods like Raman- and impedance-spectroscopy can be applied. PMID:22256298

  14. Characterization of clear cell renal cell carcinoma with diffusion kurtosis imaging: correlation between diffusion kurtosis parameters and tumor cellularity.

    PubMed

    Dai, Yongming; Yao, Qiuying; Wu, Guangyu; Wu, Dongmei; Wu, Lianming; Zhu, Li; Xue, Rong; Xu, Jianrong

    2016-07-01

    The aim of this study was to evaluate the role of diffusion kurtosis imaging (DKI) in the characterization of clear cell renal cell carcinoma (ccRCC) and to correlate DKI parameters with tumor cellularity. Fifty-nine patients with pathologically diagnosed ccRCCs were evaluated by DKI on a 3-T scanner. Regions of interest were drawn on the maps of the mean diffusion coefficient (MD) and mean diffusion kurtosis (MK). All ccRCCs were histologically graded according to the Fuhrman classification system. Tumor cellularity was measured by the nuclear-to-cytoplasm (N/C) ratio and the number of tumor cell nuclei (NTCN). ccRCCs were classified as grade 1 (n = 23), grade 2 (n = 24), grade 3 (n = 10) and grade 4 (n = 3). Both MD and MK could readily discriminate between normal renal parenchyma and ccRCCs (p < 0.001), and receiver operating characteristic (ROC) curve analysis showed that MK exhibited a better performance with an area under the ROC curve of 0.874 and sensitivity/specificity of 68.33%/100% (p < 0.001). Further, MD and MK were significantly different between grade 1 and grades 3 and 4 (p = 0.01, p < 0.001) and between grade 2 and grades 3 and 4 (p = 0.015, p < 0.005), respectively. However, no significant difference was found between grade 1 and grade 2 (p > 0.05) for both MD and MK. With regard to NTCN, no significant difference was found between any two grades (p > 0.05), and the N/C ratio changed significantly with grade (p < 0.01, between any two grades). Negative correlations were found between MK and MD (r = -0.56, p < 0.001), and between MD and N/C ratio (r = -0.36, p < 0.005), whereas MK and the N/C ratio were positively correlated (r = 0.45, p = 0.003). DKI could quantitatively characterize ccRCC with different grades by probing non-Gaussian diffusion properties related to changes in the tumor microenvironment or tissue complexities in the tumor. Copyright © 2016 John Wiley

  15. Impact of initial surface parameters on the final quality of laser micro-polished surfaces

    NASA Astrophysics Data System (ADS)

    Chow, Michael; Bordatchev, Evgueni V.; Knopf, George K.

    2012-03-01

    Laser micro-polishing (LμP) is a new laser-based microfabrication technology for improving surface quality during a finishing operation and for producing parts and surfaces with near-optical surface quality. The LμP process uses low power laser energy to melt a thin layer of material on the previously machined surface. The polishing effect is achieved as the molten material in the laser-material interaction zone flows from the elevated regions to the local minimum due to surface tension. This flow of molten material then forms a thin ultra-smooth layer on the top surface. The LμP is a complex thermo-dynamic process where the melting, flow and redistribution of molten material is significantly influenced by a variety of process parameters related to the laser, the travel motions and the material. The goal of this study is to analyze the impact of initial surface parameters on the final surface quality. Ball-end micromilling was used for preparing initial surface of samples from H13 tool steel that were polished using a Q-switched Nd:YAG laser. The height and width of micromilled scallops (waviness) were identified as dominant parameter affecting the quality of the LμPed surface. By adjusting process parameters, the Ra value of a surface, having a waviness period of 33 μm and a peak-to-valley value of 5.9 μm, was reduced from 499 nm to 301 nm, improving the final surface quality by 39.7%.

  16. Gas Transport Parameters for Landfill Final Cover Soil: Measurements and Model Modification by Dry Bulk Density

    NASA Astrophysics Data System (ADS)

    Wickramarachchi, P. N.; Kawamoto, K.; Hamamoto, S.; Nagamori, M.; Moldrup, P.; Komatsu, T.

    2011-12-01

    Landfill sites have been emerging in greenhouse warming scenarios as a significant source of atmospheric methane (CH4). Until recently, landfill management strategies have mainly addressed the problem of preventing groundwater contamination and reduction of leachate generation. Being one of the largest sources of anthropogenic CH4 emission, the final cover system should also be designed for minimizing the greenhouse gases migration into the atmosphere or the areas surrounding the landfill while securing the hydraulic performance. Compared to the intensive research efforts on hydraulic performances of landfill final cover soil, few studies about gas transport characteristics of landfill cover soils have been done. However, recent soil-gas studies implied that the effects of soil physical properties such as bulk density (i.e., compaction level), soil particle size are key parameters to understand landfill gaseous performance. The gas exchange through the final cover soils is controlled by advective and diffusive gas transport. Air permeability (ka) governs the advective gas transport while the soil-gas diffusion coefficient (Dp) governs diffusive gas transport. In this study, the effects of compaction level and particle size fraction effects on ka and Dp for landfill final cover soil was investigated. The disturbed soil samples were taken from landfill final cover in Japan. A compaction tests were performed for the soil samples with two different size fractions (< 35 mm and < 2.0 mm). In the compaction tests at field water content , the soil samples were repacked into soil cores (i.d. 15-cm, length 12-cm, 2120 cm3) at two different compaction levels [(MP):2700 kN/m2 and (SP):600 kN/m2]. After the compaction tests, ka and Dp were measured and then samples were saturated and subsequently drained at different soil-water matric potential of 0.98, 2.94, 9.81, 1235 kPa and with air-dried and oven-dried conditions. Results showed that measured Dp and ka values for the

  17. Effect of forage species during finishing on growth rate, final weight and carcass parameters from pasture finished cattle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In 2005 and 2006, angus-crossbred steers (n = 72) were used to compare growth rate, final weight and carcass parameters from pasture-finished cattle grazing cool-season mixed (MP), alfalfa (AL), or pearl millet (PM) pastures during the final 44 d of finishing. Steers were harvested on the same dates...

  18. The evaluation of non-specific cellular immunological parameters amongst children with Schistosoma haematobium infection in Nigeria.

    PubMed

    Ukwandu, N C; Nmorsi, O P; Oyahkire, G K; Nwaosu, S C; Adebayo, I A; Elemuwa, C O

    2001-10-01

    This study used the leucocyte migration index to assess cellular immune function in children with urinary schistosomiasis. Migration inhibitory factor was produced (with other lymphokines) by sensitizing mitogens. The production of antigen-induced migration inhibitory factor in vitro correlated with the in vivo state of cellular hypersensitivity of the lymphocyte donor. The percentage positive leucocyte migration rate using three mitogens was least with inactivated measles haemagglutinin virus (IMV) and highest with Bacillus Calmette-Guerin (BCG) in the control group, while highest with tuberculin purified protein derivative (PPD) and least with IMV in the test group. The measurement of the migration index of leucocytes comparing the control with lightly- and heavily-infected children on activation using three mitogens was significantly reduced, except in the case of the control versus lightly-infected children using IMV. Using IMV, the leucocyte migration index for control versus lightly-infected children and heavily-infected children was significant (p > 0.002 and p < 0.001, respectively). Using BCG the difference between controls and lightly- and heavily-infected children were significant (p < 0.02). PPD showed no significant difference in leucocyte migration between control and the lightly- or heavily-infected children. In all leucocyte migration index decreased with intensity of infection except in the case of PPD (p < 0.002 for BCG; p < 0.001 for the IMV). There was a significant correlation between egg count and leucocyte migration index; for BCG (r = -0.20, p < 0.005); for IMV (r = -0.3, p < 0.001); for PPD (r = -0.38,p < 0.001). Patients with schistosomiasis infection can express normal and effective cellular immune responses to non-schistosomal antigens and also have equal immunological ability to combat pathogens as S. haematobium-free controls. PMID:11695723

  19. Studies on the control of plant cell enlargement by cellular parameters. Final report, July 1, 1987--June 30, 1990

    SciTech Connect

    Cleland, R.E.

    1991-12-06

    The overall goal of this grant was to conduct research that would illuminate the mechanisms by which the plant hormone auxin induces plant cells to enlarge. A large body of knowledge already existed concerning this process. To begin with, it had been demonstrated, primarily by this laboratory during previous grant periods, that the effect of auxin is to cause a loosening of the cell wall, which is followed by turgor-driven wall expansion and water uptake. The wall contains a series of load-bearing wall bonds which must be cleaved in order to loosen the wall. The identification of these load-bearing bonds is one goal of this research. We proposed that an initial action of auxin is to cause cells to excrete protons, and that the resulting acidification of the apoplast activated enzymes responsible for wall loosening. Evidence has been obtained that indicates that the proton excretion is due to an enhanced activity of the plasma membrane H{sup +} {minus}ATPase. A critical question is how auxin activates this enzyme. The third project concerned the role of wall calcium as part of load-bearing wall bonds. It has long been thought that apoplastic calcium crosslinks carboxyl groups in the wall pectic substances and stiffens the walls. We examined the role of calcium-bridges as load-bearing bonds in soybean hypocotyl cell walls in two ways. The first was to measure the viscoelastic extensibility of walls after addition of exogenous calcium or removal of endogenous calcium. The second approach was to determine if removal of wall calcium from walls while under tension resulted in wall extension, as predicted if the calcium-bridges were load-bearing bonds.

  20. Semen molecular and cellular features: these parameters can reliably predict subsequent ART outcome in a goat model

    PubMed Central

    Berlinguer, Fiammetta; Madeddu, Manuela; Pasciu, Valeria; Succu, Sara; Spezzigu, Antonio; Satta, Valentina; Mereu, Paolo; Leoni, Giovanni G; Naitana, Salvatore

    2009-01-01

    Currently, the assessment of sperm function in a raw or processed semen sample is not able to reliably predict sperm ability to withstand freezing and thawing procedures and in vivo fertility and/or assisted reproductive biotechnologies (ART) outcome. The aim of the present study was to investigate which parameters among a battery of analyses could predict subsequent spermatozoa in vitro fertilization ability and hence blastocyst output in a goat model. Ejaculates were obtained by artificial vagina from 3 adult goats (Capra hircus) aged 2 years (A, B and C). In order to assess the predictive value of viability, computer assisted sperm analyzer (CASA) motility parameters and ATP intracellular concentration before and after thawing and of DNA integrity after thawing on subsequent embryo output after an in vitro fertility test, a logistic regression analysis was used. Individual differences in semen parameters were evident for semen viability after thawing and DNA integrity. Results of IVF test showed that spermatozoa collected from A and B lead to higher cleavage rates (0 < 0.01) and blastocysts output (p < 0.05) compared with C. Logistic regression analysis model explained a deviance of 72% (p < 0.0001), directly related with the mean percentage of rapid spermatozoa in fresh semen (p < 0.01), semen viability after thawing (p < 0.01), and with two of the three comet parameters considered, i.e tail DNA percentage and comet length (p < 0.0001). DNA integrity alone had a high predictive value on IVF outcome with frozen/thawed semen (deviance explained: 57%). The model proposed here represents one of the many possible ways to explain differences found in embryo output following IVF with different semen donors and may represent a useful tool to select the most suitable donors for semen cryopreservation. PMID:19900288

  1. Patient Protection and Affordable Care Act; HHS notice of benefit and payment parameters for 2016. Final rule.

    PubMed

    2015-02-27

    This final rule sets forth payment parameters and provisions related to the risk adjustment, reinsurance, and risk corridors programs; cost sharing parameters and cost-sharing reductions; and user fees for Federally-facilitated Exchanges. It also finalizes additional standards for the individual market annual open enrollment period for the 2016 benefit year, essential health benefits, qualified health plans, network adequacy, quality improvement strategies, the Small Business Health Options Program, guaranteed availability, guaranteed renewability, minimum essential coverage, the rate review program, the medical loss ratio program, and other related topics. PMID:25898427

  2. A summary of the sources of input parameter values for the Waste Isolation Pilot Plant final porosity surface calculations

    SciTech Connect

    Butcher, B.M.

    1997-08-01

    A summary of the input parameter values used in final predictions of closure and waste densification in the Waste Isolation Pilot Plant disposal room is presented, along with supporting references. These predictions are referred to as the final porosity surface data and will be used for WIPP performance calculations supporting the Compliance Certification Application to be submitted to the U.S. Environmental Protection Agency. The report includes tables and list all of the input parameter values, references citing their source, and in some cases references to more complete descriptions of considerations leading to the selection of values.

  3. Interaction between cellular voltage-sensitive conductance and network parameters in a model of neocortex can generate epileptiform bursting.

    SciTech Connect

    van Drongelen, W.; Lee, H. C.; Koch, H.; Elsen, F.; Carroll, M. S.; Hereld, M.; Stevens, R. L.; Mathematics and Computer Science; Univ. of Chicago

    2004-01-01

    We examined the effects of both intrinsic neuronal membrane properties and network parameters on oscillatory activity in a model of neocortex. A scalable network model with six different cell types was built with the pGENESIS neural simulator. The neocortical network consisted of two types of pyramidal cells and four types of inhibitory interneurons. All cell types contained both fast sodium and delayed rectifier potassium channels for generation of action potentials. A subset of the pyramidal neurons contained an additional slow inactivating (persistent) sodium current (NaP). The neurons with the NaP current showed spontaneous bursting activity in the absence of external stimulation. The model also included a routine to calculate a simulated electroencephalogram (EEG) trace from the population activity. This revealed emergent network behavior which ranged from desynchronized activity to different types of seizure-like bursting patterns. At settings with weaker excitatory network effects, the propensity to generate seizure-like behavior increased. Strong excitatory network connectivity destroyed oscillatory behavior, whereas weak connectivity enhanced the relative importance of the spontaneously bursting cells. Our findings are in contradiction with the general opinion that strong excitatory synaptic and/or insufficient inhibition effects are associated with seizure initiation, but are in agreement with previously reported behavior in neocortex.

  4. TGLF Recalibration for ITER Standard Case Parameters FY2015: Theory and Simulation Performance Target Final Report

    SciTech Connect

    Candy, J.

    2015-12-01

    flows that fit the GYRO simulations, the parameters of the model had to be tuned to each case. A physics basis for the zonal flow model was lacking. Electron energy transport at short wavelength: A secondary issue – the high-k electron energy flux – was initially assumed to be independent of the zonal flow effect. However, detailed studies of the fluctuation spectra from recent multiscale (electron and ion scale) GYRO simulations provided a critical new insight into the role of zonal flows. The multiscale simulations suggested that advection by the zonal flows strongly suppressed electron-scale turbulence. Radial shear of the zonal ExB fluctuation could not compete with the large electron-scale linear growth rate, but the kx-mixing rate of the ExB advection could. This insight led to a preliminary new model for the way zonal flows saturate both electron and ion-scale turbulence. It was also discovered that the strength of the zonal ExB velocity could be computed from the linear growth rate spectrum. The new saturation model (SAT1), which replaces the original model (SAT0), was fit to the multiscale GYRO simulations as well as the ion-scale GYRO simulations used to calibrate the original SAT0 model. Thus, SAT1 captures the physics of both multiscale electron transport and zonal-flow stabilization. In future work, it the SAT1 model will require significant further testing and (expensive) calibration with nonlinear multiscale gyrokinetic simulations over a wider variety of plasma conditions – certainly more than the small set of scans about a single C-Mod L-mode discharge. We believe the SAT1 model holds great promise as a physics-based model of the multiscale turbulent transport in fusion devices. Correction to ITER performance predictions: Finally, the impact of the SAT1model on the ITER hybrid case is mixed. Without the electron-scale contribution to the fluxes, the Dimits shift makes a significant improvement in the predicted fusion power as originally

  5. Final Technical Report - Integrated Hydrogeophysical and Hydrogeologic Driven Parameter Upscaling for Dual-Domain Transport Modeling

    SciTech Connect

    Shafer, John M

    2012-11-05

    The three major components of this research were: 1. Application of minimally invasive, cost effective hydrogeophysical techniques (surface and borehole), to generate fine scale (~1m or less) 3D estimates of subsurface heterogeneity. Heterogeneity is defined as spatial variability in hydraulic conductivity and/or hydrolithologic zones. 2. Integration of the fine scale characterization of hydrogeologic parameters with the hydrogeologic facies to upscale the finer scale assessment of heterogeneity to field scale. 3. Determination of the relationship between dual-domain parameters and practical characterization data.

  6. Parameter Resetting in Second Language Acquisition. University Research Institute Final Project Report, 1987-88.

    ERIC Educational Resources Information Center

    Phinney-Liapis, Marianne

    Analyses of the Null Subject Parameter (NSP) suggest that several factors may influence the resetting process for second language acquisition, such as specific "trigger" data, awareness of agreement as a part of awareness of agreement (INFL), and stylistic rules such as subject postposing and anaphoric reference. Four tests were administered to…

  7. Variational optimization of sub-grid scale convection parameters. Final report

    SciTech Connect

    Zivkovic-Rothman, M.

    1997-11-25

    Under the DOE CHAMMP/CLIMATE Program, a convective scheme was developed for use in climate models. The purpose of the present study was to develop an adjoint model of its tangent-linear model. the convective scheme was integrated within a single column model which provides radiative-convective equilibrium solutions applicable to climate models. The main goal of this part of the project was to develop an adjoint of the scheme to facilitate the optimization of its convective parameters. For that purpose, adjoint sensitivities were calculated with the adjoint code. Parameter optimization was based on TOGA COARE data which were also used in this study to obtain integrations of the nonlinear and tangent-linear models as well as the integrations of the adjoint model. Some inadequacies of the inner IFA data array were found, and did not permit a single numerical integration during the entire 4 months of data. However, reliable monthly radiative-convective equilibrium solutions and associated adjoint sensitivities were obtained and used to bring about the parameter optimization.

  8. Final Report: Geoelectrical Measurement of Multi-Scale Mass Transfer Parameters

    SciTech Connect

    Haggerty, Roy; Day-Lewis, Fred; Singha, Kamini; Johnson, Timothy; Binley, Andrew; Lane, John

    2014-03-20

    Mass transfer affects contaminant transport and is thought to control the efficiency of aquifer remediation at a number of sites within the Department of Energy (DOE) complex. An improved understanding of mass transfer is critical to meeting the enormous scientific and engineering challenges currently facing DOE. Informed design of site remedies and long-term stewardship of radionuclide-contaminated sites will require new cost-effective laboratory and field techniques to measure the parameters controlling mass transfer spatially and across a range of scales. In this project, we sought to capitalize on the geophysical signatures of mass transfer. Previous numerical modeling and pilot-scale field experiments suggested that mass transfer produces a geoelectrical signature—a hysteretic relation between sampled (mobile-domain) fluid conductivity and bulk (mobile + immobile) conductivity—over a range of scales relevant to aquifer remediation. In this work, we investigated the geoelectrical signature of mass transfer during tracer transport in a series of controlled experiments to determine the operation of controlling parameters, and also investigated the use of complex-resistivity (CR) as a means of quantifying mass transfer parameters in situ without tracer experiments. In an add-on component to our grant, we additionally considered nuclear magnetic resonance (NMR) to help parse mobile from immobile porosities. Including the NMR component, our revised study objectives were to: 1. Develop and demonstrate geophysical approaches to measure mass-transfer parameters spatially and over a range of scales, including the combination of electrical resistivity monitoring, tracer tests, complex resistivity, nuclear magnetic resonance, and materials characterization; and 2. Provide mass-transfer estimates for improved understanding of contaminant fate and transport at DOE sites, such as uranium transport at the Hanford 300 Area. To achieve our objectives, we implemented a 3

  9. Human cells, tissues, and cellular and tissue-based products; establishment registration and listing. Interim final rule; opportunity for public comment.

    PubMed

    2004-01-27

    The Food and Drug Administration (FDA) is issuing an interim final rule to except human dura mater and human heart valve allografts, currently subject to application or notification requirements under the Federal Food, Drug, and Cosmetic Act (the act), from the scope of the definition of "human cells, tissues, or cellular or tissue-based products (HCT/P's)" subject to the registration and listing requirements contained in 21 CFR part 1271. That definition became effective on January 21, 2004. FDA is taking this action to assure that these products, which are currently subject to the act and therefore regulated under the current good manufacturing practice regulations set out in the quality system regulations in 21 CFR part 820 are not released from the scope of those regulations before a more comprehensive regulatory framework applicable to HCT/P's, including donor suitability requirements, good tissue practice regulations, and appropriate enforcement provisions, is fully in place. When that comprehensive framework is in place, FDA intends that human dura mater and human heart valves will be subject to it. FDA intends to revoke this interim final rule at that time. PMID:14968801

  10. The effect of muscle, cooking method and final internal temperature on quality parameters of beef roast.

    PubMed

    Modzelewska-Kapituła, Monika; Dąbrowska, Ewa; Jankowska, Barbara; Kwiatkowska, Aleksandra; Cierach, Marek

    2012-06-01

    The aim of the study was to evaluate the influence of cooking conditions (dry air and steam) and final internal temperature (75, 85, 95°C) on the physico-chemical properties of beef infraspinatus (INF) and semimembranosus (SEM) muscles as well as their tenderness and juiciness. Cooking method and temperature influenced moisture, total collagen content in cooked meat and cooking loss, whereas muscle type affected fat, total collagen content and cooking loss. Warner-Bratzler shear force values were affected by cooking method, which also influenced juiciness of roasts. Temperature affected tenderness and juiciness, whereas muscle type influenced juiciness. The most desirable tenderness had INF heated in steam and dry air to 95°C. Processing SEM in dry air to 85 and 95°C lowered the juiciness of the roasts. There were significant correlations between physico-chemical, sensorial and image attributes, however high accuracy of prediction (r(2)>0.8) was achieved only for SEM muscle. PMID:22336137

  11. Patient Protection and Affordable Care Act; HHS Notice of Benefit and Payment Parameters for 2017. Final rule.

    PubMed

    2016-03-01

    This final rule sets forth payment parameters and provisions related to the risk adjustment, reinsurance, and risk corridors programs; cost-sharing parameters and cost-sharing reductions; and user fees for Federally-facilitated Exchanges. It also provides additional amendments regarding the annual open enrollment period for the individual market for the 2017 and 2018 benefit years; essential health benefits; cost sharing; qualified health plans; Exchange consumer assistance programs; network adequacy; patient safety; the Small Business Health Options Program; stand-alone dental plans; third-party payments to qualified health plans; the definitions of large employer and small employer; fair health insurance premiums; student health insurance coverage; the rate review program; the medical loss ratio program; eligibility and enrollment; exemptions and appeals; and other related topics. PMID:26964153

  12. Filtered Rayleigh scattering diagnostic for multi-parameter thermal-fluids measurements : LDRD final report.

    SciTech Connect

    Beresh, Steven Jay; Grasser, Thomas W.; Kearney, Sean Patrick; Schefer, Robert W.

    2004-01-01

    Simulation-based life-cycle-engineering and the ASCI program have resulted in models of unprecedented size and fidelity. The validation of these models requires high-resolution, multi-parameter diagnostics. Within the thermal-fluids disciplines, the need for detailed, high-fidelity measurements exceeds the limits of current engineering sciences capabilities and severely tests the state of the art. The focus of this LDRD is the development and application of filtered Rayleigh scattering (FRS) for high-resolution, nonintrusive measurement of gas-phase velocity and temperature. With FRS, the flow is laser-illuminated and Rayleigh scattering from naturally occurring sources is detected through a molecular filter. The filtered transmission may be interpreted to yield point or planar measurements of three-component velocities and/or thermodynamic state. Different experimental configurations may be employed to obtain compromises between spatial resolution, time resolution, and the quantity of simultaneously measured flow variables. In this report, we present the results of a three-year LDRD-funded effort to develop FRS combustion thermometry and Aerosciences velocity measurement systems. The working principles and details of our FRS opto-electronic system are presented in detail. For combustion thermometry we present 2-D, spatially correlated FRS results from nonsooting premixed and diffusion flames and from a sooting premixed flame. The FRS-measured temperatures are accurate to within {+-}50 K (3%) in a premixed CH4-air flame and within {+-}100 K for a vortex-strained diluted CH4-air diffusion flame where the FRS technique is severely tested by large variation in scattering cross section. In the diffusion flame work, FRS has been combined with Raman imaging of the CH4 fuel molecule to correct for the local light scattering properties of the combustion gases. To our knowledge, this is the first extension of FRS to nonpremixed combustion and the first use of joint FRS

  13. Structural parameters modulating the cellular uptake of disulfide-rich cyclic cell-penetrating peptides: MCoTI-II and SFTI-1.

    PubMed

    D'Souza, Charlotte; Henriques, Sónia Troeira; Wang, Conan K; Craik, David J

    2014-12-17

    Peptides are emerging as a new class of therapeutics due to their high potency and specificity for a range of targets, including the inhibition of protein-protein interactions. Disulfide-rich cyclic peptides, in particular, have attracted much attention in drug design due to their ultra-stable structure. Moreover, some of them have been shown to internalize into cells, which makes them potential scaffolds to deliver pharmaceutically bioactive sequences to intracellular targets. Here we examined the effects of structural modifications on the cell-penetrating properties of two disulfide-rich cyclic cell-penetrating peptides, Momordica cochinchinensis trypsin inhibitor II (MCoTI-II) and sunflower trypsin inhibitor-1 (SFTI-1). We found that the cellular uptake of MCoTI-II can be improved by increasing the overall positive charge of the native sequence. On the other hand, mutations to SFTI-1 did not significantly influence its cellular uptake, suggesting a non-specific endocytosis-dependent mechanism of cellular uptake. This study provides an understanding of the structural features affecting the internalization of MCoTI-II and SFTI-1, and hence provides a guide for the development of these disulfide-rich cyclic scaffolds into potential drug leads. PMID:24985034

  14. Investigation of the use of fly-ash based autoclaved cellular concrete blocks in coal mines for air duct work. Final report, January 25, 1993--December 31, 1994

    SciTech Connect

    Horvath, M.L.

    1995-06-19

    Coal mines are required to provide ventilation to occupied portions of underground mines. Concrete block is used in this process to construct air duct walls. However, normal concrete block is heavy and not easy to work with and eventually fails dramatically after being loaded due to mine ceiling convergence and/or floor heave. Autoclaved cellular concrete block made from (70{plus_minus}%) coal fly ash is lightweight and less rigid when loaded. It is lighter and easier to use than regular concrete block for underground mine applications. It has also been used in surface construction around the world for over 40 years. Ohio Edison along with eight other electric utility companies, the Electric Power Research Institute (EPRI), and North American Cellular Concrete constructed a mobile demonstration plant to produce autoclaved cellular concrete block from utility fly ash. To apply this research in Ohio, Ohio Edison also worked with the Ohio Coal Development Office and CONSOL Inc. to produce autoclaved cellular concrete block not only from coal ash but also from LIMB ash, SNRB ash, and PFBC ash from various clean coal technology projects sponsored by the Ohio Coal Development Office. The purpose of this project was to demonstrate the potential for beneficial use of fly ash and clean coal technology by-products in the production of lightweight block.

  15. Lack of effects on key cellular parameters of MRC-5 human lung fibroblasts exposed to 370 mT static magnetic field

    PubMed Central

    Romeo, Stefania; Sannino, Anna; Scarfì, Maria Rosaria; Massa, Rita; d’Angelo, Raffaele; Zeni, Olga

    2016-01-01

    The last decades have seen increased interest toward possible adverse effects arising from exposure to intense static magnetic fields. This concern is mainly due to the wider and wider applications of such fields in industry and clinical practice; among them, Magnetic Resonance Imaging (MRI) facilities are the main sources of exposure to static magnetic fields for both general public (patients) and workers. In recent investigations, exposures to static magnetic fields have been demonstrated to elicit, in different cell models, both permanent and transient modifications in cellular endpoints critical for the carcinogenesis process. The World Health Organization has therefore recommended in vitro investigations as important research need, to be carried out under strictly controlled exposure conditions. Here we report on the absence of effects on cell viability, reactive oxygen species levels and DNA integrity in MRC-5 human foetal lung fibroblasts exposed to 370 mT magnetic induction level, under different exposure regimens. Exposures have been performed by using an experimental apparatus designed and realized for operating with the static magnetic field generated by permanent magnets, and confined in a magnetic circuit, to allow cell cultures exposure in absence of confounding factors like heating or electric field components. PMID:26762783

  16. Lack of effects on key cellular parameters of MRC-5 human lung fibroblasts exposed to 370 mT static magnetic field.

    PubMed

    Romeo, Stefania; Sannino, Anna; Scarfì, Maria Rosaria; Massa, Rita; d'Angelo, Raffaele; Zeni, Olga

    2016-01-01

    The last decades have seen increased interest toward possible adverse effects arising from exposure to intense static magnetic fields. This concern is mainly due to the wider and wider applications of such fields in industry and clinical practice; among them, Magnetic Resonance Imaging (MRI) facilities are the main sources of exposure to static magnetic fields for both general public (patients) and workers. In recent investigations, exposures to static magnetic fields have been demonstrated to elicit, in different cell models, both permanent and transient modifications in cellular endpoints critical for the carcinogenesis process. The World Health Organization has therefore recommended in vitro investigations as important research need, to be carried out under strictly controlled exposure conditions. Here we report on the absence of effects on cell viability, reactive oxygen species levels and DNA integrity in MRC-5 human foetal lung fibroblasts exposed to 370 mT magnetic induction level, under different exposure regimens. Exposures have been performed by using an experimental apparatus designed and realized for operating with the static magnetic field generated by permanent magnets, and confined in a magnetic circuit, to allow cell cultures exposure in absence of confounding factors like heating or electric field components. PMID:26762783

  17. Early differential cell death and survival mechanisms initiate and contribute to the development of OPIDN: A study of molecular, cellular, and anatomical parameters

    SciTech Connect

    Damodaran, T.V.; Attia, M.K.; Abou-Donia, M.B.

    2011-11-15

    analysis revealed that the order of severity of damage declines from the spino-cerebellar, ventral, and dorsal tract respectively, suggesting neuroanatomical specificity. Thus, early activation of cell death and cell survival processes may play significant role in the clinical progression and syndromic clinical feature presentation of OPIDN. -- Highlights: Black-Right-Pointing-Pointer Multiple mechanisms of neurodegeneration were indicated in a study on OPIDN model. Black-Right-Pointing-Pointer Altered expressions of BCL2 and GADD45 were recorded in various tissues of CNS. Black-Right-Pointing-Pointer Multiple anomalous cellular (neuronal and astroglial) features were recorded. Black-Right-Pointing-Pointer Anatomical specificity of the neurodegeneration was described.

  18. High frequency 3-component waveform inversion for source and structural parameters. Final report, 31 December 1993--30 June 1998

    SciTech Connect

    Harvey, D.J.; Lavehio, A.L.

    1998-09-01

    The authors present the results of three studies to develop and verify techniques to classify weak seismic events. (1) The method and results of full waveform inversion for both detailed source parameters and structure parameters are described. Input data were seismograms from industrial explosions in Eastern Kazakhstan recorded by the NRDC seismic network in 1987. Very good fits were produced between the synthetic seismograms and the observed data on all three components simultaneously and for P-wave, Rayleigh wave, and Love wave. They interpreted some of the inverted source parameters as characteristic of several different types of industrial surface mining operations. (2) The same technique was used to determine detailed source and structure parameters using an event that is highly relevant to nuclear monitoring. They determined that a salt mine collapse near Solikamsk, the Ural Mountains on 5 January 1995 was most likely a mine collapse instead of an underground explosions. (3) This study was carried out jointly by the Seismology Group of the University of Colorado and the Russian team from the Int`l Institute of Earthquake Prediction Theory and Math. Geophysics. They developed a new technique to identify a seismic event based on simultaneous inversion of surface wave amplitude spectra and signs of first motions of body wave. They applied this technique to several events near the Chinese test site at Lop Nor and demonstrated significant differences in source parameters characterizing explosions and natural earthquakes in this region.

  19. In1-ghrelin, a splice variant of ghrelin gene, is associated with the evolution and aggressiveness of human neuroendocrine tumors: Evidence from clinical, cellular and molecular parameters.

    PubMed

    Luque, Raul M; Sampedro-Nuñez, Miguel; Gahete, Manuel D; Ramos-Levi, Ana; Ibáñez-Costa, Alejandro; Rivero-Cortés, Esther; Serrano-Somavilla, Ana; Adrados, Magdalena; Culler, Michael D; Castaño, Justo P; Marazuela, Mónica

    2015-08-14

    Ghrelin system comprises a complex family of peptides, receptors (GHSRs), and modifying enzymes [e.g. ghrelin-O-acyl-transferase (GOAT)] that control multiple pathophysiological processes. Aberrant alternative splicing is an emerging cancer hallmark that generates altered proteins with tumorigenic capacity. Indeed, In1-ghrelin and truncated-GHSR1b splicing variants can promote development/progression of certain endocrine-related cancers. Here, we determined the expression levels of key ghrelin system components in neuroendocrine tumor (NETs) and explored their potential functional role. Twenty-six patients with NETs were prospectively/retrospectively studied [72 samples from primary and metastatic tissues (30 normal/42 tumors)] and clinical data were obtained. The role of In1-ghrelin in aggressiveness was studied in vitro using NET cell lines (BON-1/QGP-1). In1-ghrelin, GOAT and GHSR1a/1b expression levels were elevated in tumoral compared to normal/adjacent tissues. Moreover, In1-ghrelin, GOAT, and GHSR1b expression levels were positively correlated within tumoral, but not within normal/adjacent samples, and were higher in patients with progressive vs. with stable/cured disease. Finally, In1-ghrelin increased aggressiveness (e.g. proliferation/migration) of NET cells. Altogether, our data strongly suggests a potential implication of ghrelin system in the pathogenesis and/or clinical outcome of NETs, and warrant further studies on their possible value for the future development of molecular biomarkers with diagnostic/prognostic/therapeutic value. PMID:26124083

  20. In1-ghrelin, a splice variant of ghrelin gene, is associated with the evolution and aggressiveness of human neuroendocrine tumors: Evidence from clinical, cellular and molecular parameters

    PubMed Central

    Gahete, Manuel D.; Ramos-Levi, Ana; Ibáñez-Costa, Alejandro; Rivero-Cortés, Esther; Serrano-Somavilla, Ana; Adrados, Magdalena; Culler, Michael D.; Castaño, Justo P.; Marazuela, Mónica

    2015-01-01

    Ghrelin system comprises a complex family of peptides, receptors (GHSRs), and modifying enzymes [e.g. ghrelin-O-acyl-transferase (GOAT)] that control multiple pathophysiological processes. Aberrant alternative splicing is an emerging cancer hallmark that generates altered proteins with tumorigenic capacity. Indeed, In1-ghrelin and truncated-GHSR1b splicing variants can promote development/progression of certain endocrine-related cancers. Here, we determined the expression levels of key ghrelin system components in neuroendocrine tumor (NETs) and explored their potential functional role. Twenty-six patients with NETs were prospectively/retrospectively studied [72 samples from primary and metastatic tissues (30 normal/42 tumors)] and clinical data were obtained. The role of In1-ghrelin in aggressiveness was studied in vitro using NET cell lines (BON-1/QGP-1). In1-ghrelin, GOAT and GHSR1a/1b expression levels were elevated in tumoral compared to normal/adjacent tissues. Moreover, In1-ghrelin, GOAT, and GHSR1b expression levels were positively correlated within tumoral, but not within normal/adjacent samples, and were higher in patients with progressive vs. with stable/cured disease. Finally, In1-ghrelin increased aggressiveness (e.g. proliferation/migration) of NET cells. Altogether, our data strongly suggests a potential implication of ghrelin system in the pathogenesis and/or clinical outcome of NETs, and warrant further studies on their possible value for the future development of molecular biomarkers with diagnostic/prognostic/therapeutic value. PMID:26124083

  1. Approaches to Biosimulation of Cellular Processes

    PubMed Central

    Westerhoff, H. V.

    2006-01-01

    Modelling and simulation are at the heart of the rapidly developing field of systems biology. This paper reviews various types of models, simulation methods, and theoretical approaches that are presently being used in the quantitative description of cellular processes. We first describe how molecular interaction networks can be represented by means of stoichiometric, topological and kinetic models. We briefly discuss the formulation of kinetic models using mesoscopic (stochastic) or macroscopic (continuous) approaches, and we go on to describe how detailed models of molecular interaction networks (silicon cells) can be constructed on the basis of experimentally determined kinetic parameters for cellular processes. We show how theory can help in analyzing models by applying control analysis to a recently published silicon cell model. Finally, we review some of the theoretical approaches available to analyse kinetic models and experimental data, respectively. PMID:19669467

  2. Matrix and Backstage: Cellular Substrates for Viral Vaccines

    PubMed Central

    Jordan, Ingo; Sandig, Volker

    2014-01-01

    Vaccines are complex products that are manufactured in highly dynamic processes. Cellular substrates are one critical component that can have an enormous impact on reactogenicity of the final preparation, level of attenuation of a live virus, yield of infectious units or antigens, and cost per vaccine dose. Such parameters contribute to feasibility and affordability of vaccine programs both in industrialized countries and developing regions. This review summarizes the diversity of cellular substrates for propagation of viral vaccines from primary tissue explants and embryonated chicken eggs to designed continuous cell lines of human and avian origin. PMID:24732259

  3. Methods for Predicting and Assessing the Impact of Technology on Human Resource Parameters: Report of the Literature. Final Report.

    ERIC Educational Resources Information Center

    Potter, Norman R.; Dieterly, Duncan L.

    The literature review was undertaken to establish the current status of the methodology for forecasting and assessing technology and for quantizing human resource parameters with respect to the impact of incoming technologies. The review of 140 selected documents applicable to the study was undertaken with emphasis on the identification of methods…

  4. A two parameter family of travelling waves with a singular barrier arising from the modelling of extracellular matrix mediated cellular invasion

    NASA Astrophysics Data System (ADS)

    Perumpanani, Abbey J.; Sherratt, Jonathan A.; Norbury, John; Byrne, Helen M.

    1999-02-01

    Invasive cells variously show changes in adhesion, protease production and motility. In this paper the authors develop and analyse a model for malignant invasion, brought about by a combination of proteolysis and haptotaxis. A common feature of these two mechanisms is that they can be produced by contact with the extracellular matrix through the mediation of a class of surface receptors called integrins. An unusual feature of the model is the absence of cell diffusion. By seeking travelling wave solutions the model is reduced to a system of ordinary differential equations which can be studied using phase plane analysis. The authors demonstrate the presence of a singular barrier in the phase plane and a “hole” in this singular barrier which admits a phase trajectory. The model admits a family of travelling waves which depend on two parameters, i.e. the tissue concentration of connective tissue and the rate of decay of the initial spatial profile of the invading cells. The slowest member of this family corresponds to the phase trajectory which goes through the “hole” in the singular barrier. Using a power series method the authors derive an expression relating the minimum wavespeed to the tissue concentration of the extracellular matrix which is arbitrary. The model is applicable in a wide variety of biological settings which combine haptotaxis with proteolysis. By considering various functional forms the authors show that the key mathematical features of the particular model studied in the early parts of the paper are exhibited by a wider class of models which characterise the behaviour of invading cells.

  5. Geoelectrical Measurement of Multi-Scale Mass Transfer Parameters Final Report to the Subsurface Biogeochemical Research Program

    SciTech Connect

    Day-Lewis, Frederick; Singha, Kamini; Haggerty, Roy; Johnson, Timothy; Binley, Andrew; Lane, John

    2014-03-10

    . In this project, we sought to capitalize on the geophysical signatures of mass transfer. Previous numerical modeling and pilot-scale field experiments suggested that mass transfer produces a geoelectrical signature—a hysteretic relation between sampled (mobile-domain) fluid conductivity and bulk (mobile + immobile) conductivity—over a range of scales relevant to aquifer remediation. In this work, we investigated the geoelectrical signature of mass transfer during tracer transport in a series of controlled experiments to determine the operation of controlling parameters, and also investigated the use of complex-resistivity (CR) as a means of quantifying mass transfer parameters in situ without tracer experiments. In an add-on component to our grant, we additionally considered nuclear magnetic resonance (NMR) to help parse mobile from immobile porosities. Our study objectives were to: 1. Develop and demonstrate geophysical approaches to measure mass-transfer parameters spatially and over a range of scales, including the combination of electrical resistivity monitoring, tracer tests, complex resistivity, nuclear magnetic resonance, and materials characterization; and 2. Provide mass-transfer estimates for improved understanding of contaminant fate and transport at DOE sites, such as uranium transport at the Hanford 300 Area. To achieve our objectives, we implemented a 3-part research plan involving (1) development of computer codes and techniques to estimate mass-transfer parameters from time-lapse electrical data; (2) bench-scale experiments on synthetic materials and materials from cores from the Hanford 300 Area; and (3) field demonstration experiments at the DOE’s Hanford 300 Area.

  6. Final Report for Grant No. DE-FG02-01ER63220 "The Dynamics of Cellular Stress Responses in Deinococcus radiodurans"

    SciTech Connect

    PI: Michael J. Daly, Ph.D., Uniformed Services University of the Health Sciences; Co-Investigators: James K. Fredrickson, Ph.D., Pacific Northwest National Laboratory; Richard D. Smith, Ph.D., Pacific Northwest National Laboratory; Eugene Koonin, Ph.D., National Center for Biotechnology Information; Jizhong Zhou, Ph.D. , Oak Ridge National Laboratory; Mary S. Lipton, Ph.D., Pacific Northwest National Laboratory

    2006-03-06

    Bacteria belonging to the family Deinococcaceae are some of the most ionizing radiation (IR) resistant organisms yet discovered. Deinococcus radiodurans is obligate aerobic, capable of growth under chronic IR (60 Gy/hour) and relatively resistant to many DNA damaging conditions including exposure to desiccation, ultraviolet radiation and hydrogen peroxide. The genes and cellular pathways underlying the survival strategies of D. radiodurans have been under investigation for fifty years. In the last decade, D. radiodurans was subjected to whole-genome sequencing, annotation and comparative analysis, whole-transcriptome and whole-proteome analyses, and numerous DNA repair studies. Collectively, published reports support that the key to survival of D. radiodurans resides in its ability to repair DNA, but the mechanisms responsible remain poorly defined. Unexpectedly, many novel genes implicated in recovery from IR by transcriptome and proteome profiling have had little effect on survival when disrupted, and there is reason to ask if something is missing from classical models of radiation resistance. The prevailing dogma of radiation toxicity has been that the cytotoxic and mutagenic effects of radiation are principally the result of DNA damage that occurs during IR. However, in light of available whole genome sequences, one broad observation that is difficult to reconcile with this view is that many organisms that encode a compliment of DNA repair and protection functions are killed at radiation doses that cause little DNA damage. This indicates that there are cellular targets involved in recovery that are more vulnerable to IR damage than DNA. It has been reported that D. radiodurans and other resistant organisms accumulate very high intracellular concentrations of Mn(II), and restricting the amount of Mn(II) during recovery from IR substantially reduced survival of D. radiodurans. At high intracellular concentrations, Mn(II) is known to act as a true catalyst of the

  7. Cellular resilience.

    PubMed

    Smirnova, Lena; Harris, Georgina; Leist, Marcel; Hartung, Thomas

    2015-01-01

    Cellular resilience describes the ability of a cell to cope with environmental changes such as toxicant exposure. If cellular metabolism does not collapse directly after the hit or end in programmed cell death, the ensuing stress responses promote a new homeostasis under stress. The processes of reverting "back to normal" and reversal of apoptosis ("anastasis") have been studied little at the cellular level. Cell types show astonishingly similar vulnerability to most toxicants, except for those that require a very specific target, metabolism or mechanism present only in specific cell types. The majority of chemicals triggers "general cytotoxicity" in any cell at similar concentrations. We hypothesize that cells differ less in their vulnerability to a given toxicant than in their resilience (coping with the "hit"). In many cases, cells do not return to the naive state after a toxic insult. The phenomena of "pre-conditioning", "tolerance" and "hormesis" describe this for low-dose exposures to toxicants that render the cell more resistant to subsequent hits. The defense and resilience programs include epigenetic changes that leave a "memory/scar" - an alteration as a consequence of the stress the cell has experienced. These memories might have long-term consequences, both positive (resistance) and negative, that contribute to chronic and delayed manifestations of hazard and, ultimately, disease. This article calls for more systematic analyses of how cells cope with toxic perturbations in the long-term after stressor withdrawal. A technical prerequisite for these are stable (organotypic) cultures and a characterization of stress response molecular networks. PMID:26536287

  8. In-situ parameter estimation for solar domestic hot water heating systems components. Final report, June 1995--May 1996

    SciTech Connect

    Smith, T.R.

    1997-03-01

    Three different solar domestic hot water systems are being tested at the Colorado State University Solar Energy Applications Laboratory; an unpressurized drain-back system with a load side heat exchanger, an integral collector storage system, and an ultra low flow natural convection heat exchanger system. The systems are fully instrumented to yield data appropriate for in-depth analyses of performance. The level of detail allows the observation of the performance of the total system and the performance of the individual components. This report evaluates the systems based on in-situ experimental data and compares the performances with simulated performances. The verification of the simulations aids in the rating procedure. The whole system performance measurements are also used to analyze the performance of individual components of a solar hot water system and to develop improved component models. The data are analyzed extensively and the parameters needed to characterize the systems fully are developed. Also resulting from this indepth analysis are suggested design improvements wither to the systems or the system components.

  9. Analytical Solution of Traffic Cellular Automata Model

    NASA Astrophysics Data System (ADS)

    Lo, Shih-Ching; Hsu, Chia-Hung

    2009-08-01

    Complex traffic system seems to be simulated successfully by cellular automaton (CA) models. Various models are developed to understand single-lane traffic, multilane traffic, lane-changing behavior and network traffic situations. However, the result of CA simulation can only be obtained after massive microscopic computation. Although, the mean field theory (MFT) has been studied to be the approximation of CA model, the MFT can only applied to the simple CA rules or small value of parameters. In this study, we simulate traffic flow by the NaSch model under different combination of parameters, which are maximal speed, dawdling probability and density. After that, the position of critical density, the slope of free-flow and congested regime are observed and modeled due to the simulated data. Finally, the coefficients of the model will be calibrated by the simulated data and the analytical solution of traffic CA is obtained.

  10. Final Report for NFE-07-00912: Development of Model Fuels Experimental Engine Data Base & Kinetic Modeling Parameter Sets

    SciTech Connect

    Bunting, Bruce G

    2012-10-01

    The automotive and engine industries are in a period of very rapid change being driven by new emission standards, new types of after treatment, new combustion strategies, the introduction of new fuels, and drive for increased fuel economy and efficiency. The rapid pace of these changes has put more pressure on the need for modeling of engine combustion and performance, in order to shorten product design and introduction cycles. New combustion strategies include homogeneous charge compression ignition (HCCI), partial-premixed combustion compression ignition (PCCI), and dilute low temperature combustion which are being developed for lower emissions and improved fuel economy. New fuels include bio-fuels such as ethanol or bio-diesel, drop-in bio-derived fuels and those derived from new crude oil sources such as gas-to-liquids, coal-to-liquids, oil sands, oil shale, and wet natural gas. Kinetic modeling of the combustion process for these new combustion regimes and fuels is necessary in order to allow modeling and performance assessment for engine design purposes. In this research covered by this CRADA, ORNL developed and supplied experimental data related to engine performance with new fuels and new combustion strategies along with interpretation and analysis of such data and consulting to Reaction Design, Inc. (RD). RD performed additional analysis of this data in order to extract important parameters and to confirm engine and kinetic models. The data generated was generally published to make it available to the engine and automotive design communities and also to the Reaction Design Model Fuels Consortium (MFC).

  11. Cellular growth in biofilms

    SciTech Connect

    Wood, B.D.; Whitaker, S.

    1999-09-20

    In this paper the authors develop a macroscopic evolutionary equation for the growth of the cellular phase starting from a microscopic description of mass transport and a simple structured model for product formation. The methods of continuum mechanics and volume averaging are used to develop the macroscopic representation by carefully considering the fluxes of chemical species that pertain to cell growth. The concept of structured models is extended to include the transport of reacting chemical species at the microscopic scale. The resulting macroscopic growth model is similar in form to previously published models for the transport of a single substrate and electron donor and for the production of cellular mass and exopolymer. The method of volume averaging indicated under what conditions the developed growth model is valid and provides an explicit connection between the relevant microscopic model parameters and their corresponding macroscopic counterparts.

  12. Predictability in cellular automata.

    PubMed

    Agapie, Alexandru; Andreica, Anca; Chira, Camelia; Giuclea, Marius

    2014-01-01

    Modelled as finite homogeneous Markov chains, probabilistic cellular automata with local transition probabilities in (0, 1) always posses a stationary distribution. This result alone is not very helpful when it comes to predicting the final configuration; one needs also a formula connecting the probabilities in the stationary distribution to some intrinsic feature of the lattice configuration. Previous results on the asynchronous cellular automata have showed that such feature really exists. It is the number of zero-one borders within the automaton's binary configuration. An exponential formula in the number of zero-one borders has been proved for the 1-D, 2-D and 3-D asynchronous automata with neighborhood three, five and seven, respectively. We perform computer experiments on a synchronous cellular automaton to check whether the empirical distribution obeys also that theoretical formula. The numerical results indicate a perfect fit for neighbourhood three and five, which opens the way for a rigorous proof of the formula in this new, synchronous case. PMID:25271778

  13. Quantum cellular automata

    NASA Astrophysics Data System (ADS)

    Porod, Wolfgang; Lent, Craig S.; Bernstein, Gary H.

    1994-06-01

    The Notre Dame group has developed a new paradigm for ultra-dense and ultra-fast information processing in nanoelectronic systems. These Quantum Cellular Automata (QCA's) are the first concrete proposal for a technology based on arrays of coupled quantum dots. The basic building block of these cellular arrays is the Notre Dame Logic Cell, as it has been called in the literature. The phenomenon of Coulomb exclusion, which is a synergistic interplay of quantum confinement and Coulomb interaction, leads to a bistable behavior of each cell which makes possible their use in large-scale cellular arrays. The physical interaction between neighboring cells has been exploited to implement logic functions. New functionality may be achieved in this fashion, and the Notre Dame group invented a versatile majority logic gate. In a series of papers, the feasibility of QCA wires, wire crossing, inverters, and Boolean logic gates was demonstrated. A major finding is that all logic functions may be integrated in a hierarchial fashion which allows the design of complicated QCA structures. The most complicated system which was simulated to date is a one-bit full adder consisting of some 200 cells. In addition to exploring these new concepts, efforts are under way to physically realize such structures both in semiconductor and metal systems. Extensive modeling work of semiconductor quantum dot structures has helped identify optimum design parameters for QCA experimental implementations.

  14. From Cnn Dynamics to Cellular Wave Computers

    NASA Astrophysics Data System (ADS)

    Roska, Tamas

    2013-01-01

    Embedded in a historical overview, the development of the Cellular Wave Computing paradigm is presented, starting from the standard CNN dynamics. The theoretical aspects, the physical implementation, the innovation process, as well as the biological relevance are discussed in details. Finally, the latest developments, the physical versus virtual cellular machines, as well as some open questions are presented.

  15. Microfluidic Electroporation for Cellular Analysis and Delivery

    PubMed Central

    Geng, Tao

    2013-01-01

    Electroporation is a simple yet powerful technique for breaching cell membrane barrier. The applications of electroporation can be generally divided into two categories: the release of intracellular proteins, nucleic acids and other metabolites for analysis and the delivery of exogenous reagents such as genes, drugs and nanoparticles with therapeutic purposes or for cellular manipulation. In this review, we go over the basic physics associated with cell electroporation and highlight recent technological advances on microfluidic platforms for conducting electroporation. Within the context of its working mechanism, we summarize the accumulated knowledge on how the parameters of electroporation affect its performance for various tasks. We discuss various strategies and designs for conducting electroporation at microscale and then focus on analysis of intracellular contents and delivery of exogenous agents as two major applications of the technique. Finally, an outlook for future applications of microfluidic electroporation in increasingly diverse utilities is presented. PMID:23917998

  16. Cellular automaton for chimera states

    NASA Astrophysics Data System (ADS)

    García-Morales, Vladimir

    2016-04-01

    A minimalistic model for chimera states is presented. The model is a cellular automaton (CA) which depends on only one adjustable parameter, the range of the nonlocal coupling, and is built from elementary cellular automata and the majority (voting) rule. This suggests the universality of chimera-like behavior from a new point of view: Already simple CA rules based on the majority rule exhibit this behavior. After a short transient, we find chimera states for arbitrary initial conditions, the system spontaneously splitting into stable domains separated by static boundaries, some synchronously oscillating and the others incoherent. When the coupling range is local, nontrivial coherent structures with different periodicities are formed.

  17. Micro/Nanoscale Thermometry for Cellular Thermal Sensing.

    PubMed

    Bai, Tingting; Gu, Ning

    2016-09-01

    Temperature is a key parameter to regulate cell function, and biochemical reactions inside a cell in turn affect the intracellular temperature. It's vitally necessary to measure cellular temperature to provide sufficient information to fully understand life science, while the conventional methods are incompetent. Over the last decade, many ingenious thermometers have been developed with the help of nanotechnology, and real-time intracellular temperature measurement at the micro/nanoscale has been realized with high temporal-spatial resolution. With the help of these techniques, several mechanisms of thermogenesis inside cells have been investigated, even in subcellular organelles. Here, current developments in cellular thermometers are highlighted, and a picture of their applications in cell biology is presented. In particular, temperature measurement principle, thermometer design and latest achievements are also introduced. Finally, the existing opportunities and challenges in this ongoing field are discussed. PMID:27172908

  18. Cellular Stress Responses and Monitored Cellular Activities.

    PubMed

    Sawa, Teiji; Naito, Yoshifumi; Kato, Hideya; Amaya, Fumimasa

    2016-08-01

    To survive, organisms require mechanisms that enable them to sense changes in the outside environment, introduce necessary responses, and resist unfavorable distortion. Consequently, through evolutionary adaptation, cells have become equipped with the apparatus required to monitor their fundamental intracellular processes and the mechanisms needed to try to offset malfunction without receiving any direct signals from the outside environment. It has been shown recently that eukaryotic cells are equipped with a special mechanism that monitors their fundamental cellular functions and that some pathogenic proteobacteria can override this monitoring mechanism to cause harm. The monitored cellular activities involved in the stressed intracellular response have been researched extensively in Caenorhabditis elegans, where discovery of an association between key mitochondrial activities and innate immune responses was named "cellular associated detoxification and defenses (cSADD)." This cellular surveillance pathway (cSADD) oversees core cellular activities such as mitochondrial respiration and protein transport into mitochondria, detects xenobiotics and invading pathogens, and activates the endocrine pathways controlling behavior, detoxification, and immunity. The cSADD pathway is probably associated with cellular responses to stress in human inflammatory diseases. In the critical care field, the pathogenesis of lethal inflammatory syndromes (e.g., respiratory distress syndromes and sepsis) involves the disturbance of mitochondrial respiration leading to cell death. Up-to-date knowledge about monitored cellular activities and cSADD, especially focusing on mitochondrial involvement, can probably help fill a knowledge gap regarding the pathogenesis of lethal inflammatory syndromes in the critical care field. PMID:26954943

  19. Continuum representations of cellular solids

    SciTech Connect

    Neilsen, M.K.

    1993-09-01

    Cellular materials consist of interconnected struts or plates which form cells. The struts or plates are constructed from a variety of metals, polymers, ceramics and wood products. Cellular materials are often used in impact limiters for shipping containers to protect the contents from accidental impact events. These materials exhibit a variety of complex behavior when subjected to crushing loads. This research focuses on the development of continuum representations of cellular solids that can be used in the finite element analysis of shipping container accidents. A significant portion of this work is the development of a new methodology to relate localized deformations to appropriate constitutive descriptions. This methodology provides the insight needed to select constitutive descriptions for cellular solids that capture the localized deformations that are observed experimentally. Constitutive relations are developed for two different cellular materials, aluminum honeycomb and polyurethane foam. These constitutive relations are based on plasticity and continuum damage theories. Plasticity is used to describe the permanent deformation exhibited by both aluminum honeycomb and polyurethane foam. Continuum damage is needed to capture the change in elastic parameters due to cracking of the polyurethane cell wall materials. The new constitutive description of polyurethane foam is implemented in both static and dynamic finite element codes, and analytical and numerical predictions are compared with available experimental data.

  20. Cellular Phone Towers

    MedlinePlus

    ... the call. How are people exposed to the energy from cellular phone towers? As people use cell ... where people can be exposed to them. The energy from a cellular phone tower antenna, like that ...

  1. Hierarchical cellular materials

    SciTech Connect

    Gibson, L.J.

    1991-01-01

    In this paper a method for estimating the contributions of both the composite and the cellular microstructures to the overall material properties and the mechanical efficiency of natural cellular solids will be described. The method will be demonstrated by focusing on the Young's modulus; similar techniques can be used for other material properties. The results suggest efficient microstructures for engineered cellular materials.

  2. Hierarchical cellular materials

    SciTech Connect

    Gibson, L.J.

    1991-12-31

    In this paper a method for estimating the contributions of both the composite and the cellular microstructures to the overall material properties and the mechanical efficiency of natural cellular solids will be described. The method will be demonstrated by focusing on the Young`s modulus; similar techniques can be used for other material properties. The results suggest efficient microstructures for engineered cellular materials.

  3. Active Cellular Nematics

    NASA Astrophysics Data System (ADS)

    Duclos, Guillaume; Erlenkaemper, Christoph; Garcia, Simon; Yevick, Hannah; Joanny, Jean-François; Silberzan, Pascal; Biology inspired physics at mesoscales Team; Physical approach of biological problems Team

    We study the emergence of a nematic order in a two-dimensional tissue of apolar elongated fibroblast cells. Initially, these cells are very motile and the monolayer is characterized by giant density fluctuations, a signature of far-from-equilibrium systems. As the cell density increases because of proliferation, the cells align with each other forming large perfectly oriented domains while the cellular movements slow down and eventually freeze. Therefore topological defects characteristic of nematic phases remain trapped at long times, preventing the development of infinite domains. By analogy with classical non-active nematics, we have investigated the role of boundaries and we have shown that cells confined in stripes of width smaller than typically 500 µm are perfectly aligned in the stripe direction. Experiments performed in cross-shaped patterns show that both the number of cells and the degree of alignment impact the final orientation. Reference: Duclos G., Garcia S., Yevick H.G. and Silberzan P., ''Perfect nematic order in confined monolayers of spindle-shaped cells'', Soft Matter, 10, 14, 2014

  4. Approximation methods for the identification and control of distributed-parameter systems. Final technical report, 1 October 1984-30 September 1987

    SciTech Connect

    Rosen, I.G.

    1987-11-20

    Efforts to develop computational methods for the identification and optimal control of linear and nonlinear systems governed by distributed-parameter systems are reported on. Specifically, approximation methods for determining Optimal LOG compensators (feedback control and estimator gains) and functional parameters in linear and nonlinear partial differential equations and hereditary systems were developed, analyzed, and tested. The study included theoretical, experimental, and numerical components. Covergence theories for spline-based and modal finite-element schemes were established, and extensive numerical studies on both conventional (serial) and vector supercomputers were carried out. A parameter estimation scheme was tested using experimental data taken from the RPL structure, a laboratory experiment designed to test control algorithms for the large-angle slewing of spacecraft with flexible appendages, and other projects involving the identification of flexible structures based upon experimental data were initiated.

  5. Sensitivity-constrained nonlinear programming: a general approach for planning and design under parameter uncertainty and an application to treatment plant design. Final report

    SciTech Connect

    Uber, J.G.; Kao, J.J.; Brill, E.D.; Pfeffer, J.T.

    1988-01-01

    One important problem with using mathematical models is that parameter values, and thus the model results, are often uncertain. A general approach, Sensitivity Constrained Nonlinear Programming (SCNLP), was developed for extending nonlinear optimization models to include functions that depend on the system sensitivity to changes in parameter values. Such sensitivity-based functions include first-order measures of variance, reliability, and robustness. Thus SCNLP can be used to generate solutions or designs that are good with respect to modeled objectives, and that also reflect concerns about uncertainty in parameter values. A solution procedure and an implementation based on an existing nonlinear-programming code are presented. SCNLP was applied to a complex activated sludge waste-water treatment plant design problem.

  6. Modelling cellular behaviour

    NASA Astrophysics Data System (ADS)

    Endy, Drew; Brent, Roger

    2001-01-01

    Representations of cellular processes that can be used to compute their future behaviour would be of general scientific and practical value. But past attempts to construct such representations have been disappointing. This is now changing. Increases in biological understanding combined with advances in computational methods and in computer power make it possible to foresee construction of useful and predictive simulations of cellular processes.

  7. Parametric study of double cellular detonation structure

    NASA Astrophysics Data System (ADS)

    Khasainov, B.; Virot, F.; Presles, H.-N.; Desbordes, D.

    2013-05-01

    A parametric numerical study is performed of a detonation cellular structure in a model gaseous explosive mixture whose decomposition occurs in two successive exothermic reaction steps with markedly different characteristic times. Kinetic and energetic parameters of both reactions are varied in a wide range in the case of one-dimensional steady and two-dimensional (2D) quasi-steady self-supported detonations. The range of governing parameters of both exothermic steps is defined where a "marked" double cellular structure exists. It is shown that the two-level cellular structure is completely governed by the kinetic parameters and the local overdrive ratio of the detonation front propagating inside large cells. Furthermore, since it is quite cumbersome to use detailed chemical kinetics in unsteady 2D case, the proposed work should help to identify the mixtures and the domain of their equivalence ratio where double detonation structure could be observed.

  8. Universal map for cellular automata

    NASA Astrophysics Data System (ADS)

    García-Morales, V.

    2012-08-01

    A universal map is derived for all deterministic 1D cellular automata (CAs) containing no freely adjustable parameters and valid for any alphabet size and any neighborhood range (including non-symmetrical neighborhoods). The map can be extended to an arbitrary number of dimensions and topologies and to arbitrary order in time. Specific CA maps for the famous Conway's Game of Life and Wolfram's 256 elementary CAs are given. An induction method for CAs, based in the universal map, allows mathematical expressions for the orbits of a wide variety of elementary CAs to be systematically derived.

  9. Stochastic extension of cellular manufacturing systems: a queuing-based analysis

    NASA Astrophysics Data System (ADS)

    Fardis, Fatemeh; Zandi, Afagh; Ghezavati, Vahidreza

    2013-07-01

    Clustering parts and machines into part families and machine cells is a major decision in the design of cellular manufacturing systems which is defined as cell formation. This paper presents a non-linear mixed integer programming model to design cellular manufacturing systems which assumes that the arrival rate of parts into cells and machine service rate are stochastic parameters and described by exponential distribution. Uncertain situations may create a queue behind each machine; therefore, we will consider the average waiting time of parts behind each machine in order to have an efficient system. The objective function will minimize summation of idleness cost of machines, sub-contracting cost for exceptional parts, non-utilizing machine cost, and holding cost of parts in the cells. Finally, the linearized model will be solved by the Cplex solver of GAMS, and sensitivity analysis will be performed to illustrate the effectiveness of the parameters.

  10. Key Eco-Hydrological Parameters Retrieval and Land Data Assimilation System Development in a Typical Inland River Basin of China's Arid Region- Final Results

    NASA Astrophysics Data System (ADS)

    Li, Xin; Wang, Shuguo; Han, Xujun

    2013-01-01

    During Dragon 2 period, fruitful results have been achieved with regard to the estimation of land surface parameters and the development of a catchment scale land data assimilation system in the Heihe River Basin (HRB), China. By using multi-platforms (satellite, aircraft, crane-based, ground station etc.), various observation results have been obtained, paving the way for carrying out a variety of dedicated and novel retrieval investigations related to eco-hydrological parameters, e.g. precipitation, snow properties, soil moisture (SM), land surface temperature (LST), evapotranspiration (ET), canopy resistance, leaf chlorophyll content, bi-directional reflectance, albedo. In addition, the Heihe data assimilation system has been developed to make use of these multi-source observations at the catchment scale, in order to improve the estimation of SM, soil temperature, ET, snow and streamflow at 1 km spatial resolution with a temporal resolution of 1 hour.

  11. Project to develop an index of pc 3,4,5 geomagnetic pulsations and to study their control by solar wind parameters. Final report

    SciTech Connect

    Greenstadt, E.W.

    1983-04-01

    This report summarizes the recent activities and results of a study seeking to discover and quantify the relationship between solar wind parameters, magnetosheath turbulence, and daytime geomagnetic pulsations. The most significant achievement has been a major advance in data processing and computational analysis leading to the first observations and measurements of magnetospheric resonance thickness, wave transfer across the magnetopause, and wave structure in the outer magnetosheath.

  12. Cellular Reflectarray Antenna

    NASA Technical Reports Server (NTRS)

    Romanofsky, Robert R.

    2010-01-01

    The cellular reflectarray antenna is intended to replace conventional parabolic reflectors that must be physically aligned with a particular satellite in geostationary orbit. These arrays are designed for specified geographical locations, defined by latitude and longitude, each called a "cell." A particular cell occupies nominally 1,500 square miles (3,885 sq. km), but this varies according to latitude and longitude. The cellular reflectarray antenna designed for a particular cell is simply positioned to align with magnetic North, and the antenna surface is level (parallel to the ground). A given cellular reflectarray antenna will not operate in any other cell.

  13. CELLULAR MAGNESIUM HOMEOSTASIS

    PubMed Central

    Romani, Andrea M.P.

    2011-01-01

    Magnesium, the second most abundant cellular cation after potassium, is essential to regulate numerous cellular functions and enzymes, including ion channels, metabolic cycles, and signaling pathways, as attested by more than 1000 entries in the literature. Despite significant recent progress, however, our understanding of how cells regulate Mg2+ homeostasis and transport still remains incomplete. For example, the occurrence of major fluxes of Mg2+ in either direction across the plasma membrane of mammalian cells following metabolic or hormonal stimuli has been extensively documented. Yet, the mechanisms ultimately responsible for magnesium extrusion across the cell membrane have not been cloned. Even less is known about the regulation in cellular organelles. The present review is aimed at providing the reader with a comprehensive and up-to-date understanding of the mechanisms enacted by eukaryotic cells to regulate cellular Mg2+ homeostasis and how these mechanisms are altered under specific pathological conditions. PMID:21640700

  14. Integration of real-time air pollution parameters into the decision making process regarding highway construction work zone traffic flow. Final report

    SciTech Connect

    Fatagoma, O.; Premo, T.; Jacko, R.B.

    1998-05-15

    The main objective of this research is to develop a real-time modal exhaust emission concentration model for light and medium duty vehicles using real-time emission concentration, traffic, and meteorological data. The data were collected during the Purdue Vehicle Emission Monitoring and Modeling Project (PVEMP) field experiments conducted in the spring and summer 1997 on the Borman Expressway. The implementation of the model and the results of the project integrate air quality as another parameter in the traffic flow improvement of the Borman Expressway, especially in construction zones. This paper presents the results of the monitoring program, the data reduction and analysis effort, the development of the real-time modal exhaust emission concentration model, and the implementation suggestions of the research.

  15. Cellular immune response experiment MA-031

    NASA Technical Reports Server (NTRS)

    Criswell, B. S.

    1976-01-01

    Significant changes in phytohemagglutinin (PHA) lymphocytic responsiveness occurred in the cellular immune response of three astronauts during the 9 day flight of the Apollo Soyuz Test Project. Parameters studied were white blood cell concentrations, lymphocyte numbers, B- and T-lymphocyte distributions in peripheral blood, and lymphocyte responsiveness to PHA, pokeweed mitogen, Concanavalin A, and influenza virus antigen.

  16. Cellular reprogramming and hepatocellular carcinoma development.

    PubMed

    Zheng, Yun-Wen; Nie, Yun-Zhong; Taniguchi, Hideki

    2013-12-21

    Hepatocellular carcinoma (HCC) is one of the most common cancers, and is also the leading cause of death worldwide. Studies have shown that cellular reprogramming contributes to chemotherapy and/or radiotherapy resistance and the recurrence of cancers. In this article, we summarize and discuss the latest findings in the area of cellular reprogramming in HCC. The aberrant expression of transcription factors OCT4, KLF4, SOX2, c-MYC, NANOG, and LIN28 have been also observed, and the expression of these transcription factors is associated with unfavorable clinical outcomes in HCC. Studies indicate that cellular reprogramming may play a critical role in the occurrence and recurrence of HCC. Recent reports have shown that DNA methylation, miRNAs, tumor microenvironment, and signaling pathways can induce the expression of stemness transcription factors, which leads to cellular reprogramming in HCC. Furthermore, studies indicate that therapies based on cellular reprogramming could revolutionize HCC treatment. Finally, a novel therapeutic concept is discussed: reprogramming control therapy. A potential reprogramming control therapy method could be developed based on the reprogramming demonstrated in HCC studies and applied at two opposing levels: differentiation and reprogramming. Our increasing understanding and control of cellular programming should facilitate the exploitation of this novel therapeutic concept and its application in clinical HCC treatment, which may represent a promising strategy in the future that is not restricted to liver cancer. PMID:24379607

  17. Autophagy in cellular metabolism and cancer

    PubMed Central

    Jiang, Xuejun; Overholtzer, Michael; Thompson, Craig B.

    2015-01-01

    Autophagy is a catabolic process mediated by incorporation of cellular material into cytosolic membrane vesicles for lysosomal degradation. It is crucial for maintaining cell viability and homeostasis in response to numerous stressful conditions. In this Review, the role of autophagy in both normal biology and disease is discussed. Emphasis is given to the interplay of autophagy with nutrient signaling through the ULK1 autophagy pre-initiation complex. Furthermore, related cellular processes utilizing components of the canonical autophagy pathway are discussed due to their potential roles in nutrient scavenging. Finally, the role of autophagy in cancer and its potential as a cancer therapeutic target are considered. PMID:25654550

  18. Irregular Cellular Learning Automata.

    PubMed

    Esnaashari, Mehdi; Meybodi, Mohammad Reza

    2015-08-01

    Cellular learning automaton (CLA) is a recently introduced model that combines cellular automaton (CA) and learning automaton (LA). The basic idea of CLA is to use LA to adjust the state transition probability of stochastic CA. This model has been used to solve problems in areas such as channel assignment in cellular networks, call admission control, image processing, and very large scale integration placement. In this paper, an extension of CLA called irregular CLA (ICLA) is introduced. This extension is obtained by removing the structure regularity assumption in CLA. Irregularity in the structure of ICLA is needed in some applications, such as computer networks, web mining, and grid computing. The concept of expediency has been introduced for ICLA and then, conditions under which an ICLA becomes expedient are analytically found. PMID:25291810

  19. Cellular Homeostasis and Aging.

    PubMed

    Hartl, F Ulrich

    2016-06-01

    Aging and longevity are controlled by a multiplicity of molecular and cellular signaling events that interface with environmental factors to maintain cellular homeostasis. Modulation of these pathways to extend life span, including insulin-like signaling and the response to dietary restriction, identified the cellular machineries and networks of protein homeostasis (proteostasis) and stress resistance pathways as critical players in the aging process. A decline of proteostasis capacity during aging leads to dysfunction of specific cell types and tissues, rendering the organism susceptible to a range of chronic diseases. This volume of the Annual Review of Biochemistry contains a set of two reviews addressing our current understanding of the molecular mechanisms underlying aging in model organisms and humans. PMID:27050288

  20. Architected Cellular Materials

    NASA Astrophysics Data System (ADS)

    Schaedler, Tobias A.; Carter, William B.

    2016-07-01

    Additive manufacturing enables fabrication of materials with intricate cellular architecture, whereby progress in 3D printing techniques is increasing the possible configurations of voids and solids ad infinitum. Examples are microlattices with graded porosity and truss structures optimized for specific loading conditions. The cellular architecture determines the mechanical properties and density of these materials and can influence a wide range of other properties, e.g., acoustic, thermal, and biological properties. By combining optimized cellular architectures with high-performance metals and ceramics, several lightweight materials that exhibit strength and stiffness previously unachievable at low densities were recently demonstrated. This review introduces the field of architected materials; summarizes the most common fabrication methods, with an emphasis on additive manufacturing; and discusses recent progress in the development of architected materials. The review also discusses important applications, including lightweight structures, energy absorption, metamaterials, thermal management, and bioscaffolds.

  1. Toxicity of carbon monoxide-hydrogen cyanide gas mixtures: Expose concentration, time-to-incapacitation, carboxyhemoglobin, and blood cyanide parameters. Final report

    SciTech Connect

    Sanders, D.C.; Chaturvedi, A.K.; Endecott, B.R.; Ritter, R.M.; Vu, N.

    1994-04-01

    During aircraft interior fires, carbon monoxide (CO) and hydrogen cyanide (HCN) are produced in sufficient amounts to cause incapacitation and death. Time-to-incapacitation (ti) is a practical parameter for estimating escape time in fire environments. Exposures to CO-HCN mixtures have demonstrated that these gases have additive effects (producing shorter times to incapacitation), but the resulting concentrations of carboxyhemoglobin (COHb) and blood cyanide (CN-) at incapacitation are not well defined. These undefined relationships between COHb and blood CN- levels and the onset of incapacitation make the interpretation of postmortem levels difficult for medical accident investigators. To explore these relationships, ti was determined in laboratory rats exposed to two CO-HCN mixtures consisting of CO and HCN concentrations that produce 5- and 35-min ti in individual gas exposures; COHb and blood CN- concentrations were determined at incapacitation. In the high concentration CO-HCN mixture, the resultant ti was shortened from 5 min to 2.6 min; COHb dropped from 81% to 55% and CN- from 2.3 microns/mL to 1.1 microns/mL. At the lower concentration COHCN mixture, where the resultant ti was reduced from 35 min to 11.1 min, COHb dropped from 71% to 61% and blood CN- decreased from 4.2 microns/mL to 1.1 microns/mL. Comparison of the COHb and blood CN- values with the values from our signal gas exposure studies indicated that any alteration of the uptake of either gas in blood by the presence of the other was minimal. These findings suggest that changes in COHb and blood CN- may not be directly correlated with the onset of incapacitation and that postmortem blood levels should be carefully evaluated, particularly when both gases are present.

  2. Effects of electromagnetic field stimulation on cellular signal transduction mechanisms: Analyses of the effects of low frequency electromagnetic fields on calcium spiking in ROS 17/2.8 cells. Final report

    SciTech Connect

    Sisken, B.F.; Sisken, J.E.

    1997-12-01

    The general goals of this work were to determine whether resting levels of cellular second messengers, especially calcium, are affected by low-level electromagnetic fields and the mechanisms that could lead to such changes. The work performed was directed at (1) verifying the report of McLeod et al (1990) that low frequency sinusoidal EMF can alter basal calcium fluctuations in cultured ROS 17/2.8 osteoblast-like cells and (2) reproducing the findings of Luben et al (1982) that pulsed electromagnetic fields can affect PTH-stimulated adenylate cyclase activity in osteoblasts. Initially a system was constructed so that cells could be exposed to sinusoidal electric fields using platinum electrodes. In this system, the electrodes were separated from the cells and culture medium by agar barriers. A series of experiments indicated that this system was subject to a significant, though little-known artifact in which a not well understood interaction between the electrodes and sodium ions in the medium or in plain salt solutions led to frequency and amplitude dependent emission of photons that are recorded by the detection system. They therefore designed and constructed an air gap reactor system that utilizes a ferromagnetic core to direct the magnetic flux generated by a sinusoidal coil. Studies on the effects of a 15 Hz pulsed electromagnetic field (PEMF) on cyclic AMP metabolism were performed on ROS 17/2.8 and MC3T3 cells.

  3. Measuring information flow in cellular networks by the systems biology method through microarray data

    PubMed Central

    Chen, Bor-Sen; Li, Cheng-Wei

    2015-01-01

    In general, it is very difficult to measure the information flow in a cellular network directly. In this study, based on an information flow model and microarray data, we measured the information flow in cellular networks indirectly by using a systems biology method. First, we used a recursive least square parameter estimation algorithm to identify the system parameters of coupling signal transduction pathways and the cellular gene regulatory network (GRN). Then, based on the identified parameters and systems theory, we estimated the signal transductivities of the coupling signal transduction pathways from the extracellular signals to each downstream protein and the information transductivities of the GRN between transcription factors in response to environmental events. According to the proposed method, the information flow, which is characterized by signal transductivity in coupling signaling pathways and information transductivity in the GRN, can be estimated by microarray temporal data or microarray sample data. It can also be estimated by other high-throughput data such as next-generation sequencing or proteomic data. Finally, the information flows of the signal transduction pathways and the GRN in leukemia cancer cells and non-leukemia normal cells were also measured to analyze the systematic dysfunction in this cancer from microarray sample data. The results show that the signal transductivities of signal transduction pathways change substantially from normal cells to leukemia cancer cells. PMID:26082788

  4. Genetic Dominance & Cellular Processes

    ERIC Educational Resources Information Center

    Seager, Robert D.

    2014-01-01

    In learning genetics, many students misunderstand and misinterpret what "dominance" means. Understanding is easier if students realize that dominance is not a mechanism, but rather a consequence of underlying cellular processes. For example, metabolic pathways are often little affected by changes in enzyme concentration. This means that…

  5. Auxin and Cellular Elongation.

    PubMed

    Velasquez, Silvia Melina; Barbez, Elke; Kleine-Vehn, Jürgen; Estevez, José M

    2016-03-01

    Auxin is a crucial growth regulator in plants. However, a comprehensive understanding of how auxin induces cell expansion is perplexing, because auxin acts in a concentration- and cell type-dependent manner. Consequently, it is desirable to focus on certain cell types to exemplify the underlying growth mechanisms. On the other hand, plant tissues display supracellular growth (beyond the level of single cells); hence, other cell types might compromise the growth of a certain tissue. Tip-growing cells do not display neighbor-induced growth constraints and, therefore, are a valuable source of information for growth-controlling mechanisms. Here, we focus on auxin-induced cellular elongation in root hairs, exposing a mechanistic view of plant growth regulation. We highlight a complex interplay between auxin metabolism and transport, steering root hair development in response to internal and external triggers. Auxin signaling modules and downstream cascades of transcription factors define a developmental program that appears rate limiting for cellular growth. With this knowledge in mind, the root hair cell is a very suitable model system in which to dissect cellular effectors required for cellular expansion. PMID:26787325

  6. The New Cellular Immunology

    ERIC Educational Resources Information Center

    Claman, Henry N.

    1973-01-01

    Discusses the nature of the immune response and traces many of the discoveries that have led to the present state of knowledge in immunology. The new cellular immunology is directing its efforts toward improving health by proper manipulation of the immune mechanisms of the body. (JR)

  7. Teaching cellular engineering.

    PubMed

    Hammer, Daniel A; Waugh, Richard E

    2006-02-01

    Cellular engineering is one of the fastest growing subdisciplines in the field of Biomedical Engineering. It involves the application of engineering analysis to understand and control cellular behavior, with the ultimate objective of developing novel therapeutic or diagnostic approaches for the clinic or harnessing cellular function for commercial applications. Well-educated students in this area need strong foundational knowledge in engineering science, chemistry, and cell and molecular biology. In undergraduate curricula, the challenge is to include essential engineering skills plus appropriate levels of training in chemistry and biology while satisfying accreditation-mandated breadth in engineering training. At the graduate level, educators must accommodate students with diverse backgrounds and provide them with both a state-of-the-art understanding of the life sciences and the most advanced engineering skills. Engineering curricular content should include mechanics and materials, physical chemistry, transport phenomena, and control theory. Training from faculty with appointments and research programs in the life sciences is generally recommended, and additional life science content should also be integrated within the engineering curriculum. A capstone course in cellular engineering that includes opportunities for students to have hands-on experiences with state-of-the-art laboratory techniques is highly recommended. PMID:16450196

  8. Infrared image enhancement using Cellular Automata

    NASA Astrophysics Data System (ADS)

    Qi, Wei; Han, Jing; Zhang, Yi; Bai, Lian-fa

    2016-05-01

    Image enhancement is a crucial technique for infrared images. The clear image details are important for improving the quality of infrared images in computer vision. In this paper, we propose a new enhancement method based on two priors via Cellular Automata. First, we directly learn the gradient distribution prior from the images via Cellular Automata. Second, considering the importance of image details, we propose a new gradient distribution error to encode the structure information via Cellular Automata. Finally, an iterative method is applied to remap the original image based on two priors, further improving the quality of enhanced image. Our method is simple in implementation, easy to understand, extensible to accommodate other vision tasks, and produces more accurate results. Experiments show that the proposed method performs better than other methods using qualitative and quantitative measures.

  9. Fabrication of cellular materials

    NASA Astrophysics Data System (ADS)

    Prud'homme, Robert K.; Aksay, Ilhan A.; Garg, Rajeev

    1996-02-01

    Nature uses cellular materials in applications requiring strength while, simultaneously, minimizing raw materials requirements. Minimizing raw materials is efficient both in terms of the energy expended by the organism to synthesize the structure and in terms of the strength- to-weight ratio of the structure. Wood is the most obvious example of cellular bio-materials, and it is the focus of other presentations in this symposium. The lightweight bone structure of birds is another excellent example where weight is a key criterion. The anchoring foot of the common muscle [Mytilus edulis] whereby it attaches itself to objects is a further example of a biological system that uses a foam to fill space and yet conserve on raw materials. In the case of the muscle the foam is water filled and the foot structure distributes stress over a larger area so that the strength of the byssal thread from which it is suspended is matched to the strength of interfacial attachment of the foot to a substrate. In these examples the synthesis and fabrication of the cellular material is directed by intercellular, genetically coded, biochemical reactions. The resulting cell sizes are microns in scale. Cellular materials at the next larger scale are created by organisms at the next higher level of integration. For example an African tree frog lays her eggs in a gas/fluid foam sack she builds on a branch overhanging a pond. The outside of the foam sack hardens in the sun and prevents water evaporation. The foam structure minimizes the amount of fluid that needs to be incorporated into the sack and minimizes its weight. However, as far as the developing eggs are concerned, they are in an aqueous medium, i.e. the continuous fluid phase of the foam. After precisely six days the eggs hatch, and the solidified outer wall re-liquefies and dumps the emerging tadpoles into the pond below. The bee honeycomb is an example of a cellular material with exquisite periodicity at millimeter length scales. The

  10. Radiolabeled cellular blood elements

    SciTech Connect

    Thakur, M.L.; Ezikowitz, M.D.; Hardeman, M.R.

    1985-01-01

    This book contains papers delivered by guest lectures and participants at the Advanced Study Institute's colloquium on Radiolabeled Cellular Blood Elements at Maratea, Italy on August 29, to September 9, 1982. The book includes chapters on basic cell physiology and critical reviews of data and experience in the preparation and use of radiolabeled cells, as well as reports on very recent developments, from a faculty that included experts on cell physiology in health and disease and on the technology of in vivo labeling.

  11. Cellular dysfunction in sepsis.

    PubMed

    Singer, Mervyn

    2008-12-01

    Cellular dysfunction is a commonplace sequelum of sepsis and other systemic inflammatory conditions. Impaired energy production (related to mitochondrial inhibition, damage, and reduced protein turnover) appears to be a core mechanism underlying the development of organ dysfunction. The reduction in energy availability appears to trigger a metabolic shutdown that impairs normal functioning of the cell. This may well represent an adaptive mechanism analogous to hibernation that prevents a massive degree of cell death and thus enables eventual recovery in survivors. PMID:18954700

  12. Stability of Stochastic Neutral Cellular Neural Networks

    NASA Astrophysics Data System (ADS)

    Chen, Ling; Zhao, Hongyong

    In this paper, we study a class of stochastic neutral cellular neural networks. By constructing a suitable Lyapunov functional and employing the nonnegative semi-martingale convergence theorem we give some sufficient conditions ensuring the almost sure exponential stability of the networks. The results obtained are helpful to design stability of networks when stochastic noise is taken into consideration. Finally, two examples are provided to show the correctness of our analysis.

  13. Probabilistic cellular automata.

    PubMed

    Agapie, Alexandru; Andreica, Anca; Giuclea, Marius

    2014-09-01

    Cellular automata are binary lattices used for modeling complex dynamical systems. The automaton evolves iteratively from one configuration to another, using some local transition rule based on the number of ones in the neighborhood of each cell. With respect to the number of cells allowed to change per iteration, we speak of either synchronous or asynchronous automata. If randomness is involved to some degree in the transition rule, we speak of probabilistic automata, otherwise they are called deterministic. With either type of cellular automaton we are dealing with, the main theoretical challenge stays the same: starting from an arbitrary initial configuration, predict (with highest accuracy) the end configuration. If the automaton is deterministic, the outcome simplifies to one of two configurations, all zeros or all ones. If the automaton is probabilistic, the whole process is modeled by a finite homogeneous Markov chain, and the outcome is the corresponding stationary distribution. Based on our previous results for the asynchronous case-connecting the probability of a configuration in the stationary distribution to its number of zero-one borders-the article offers both numerical and theoretical insight into the long-term behavior of synchronous cellular automata. PMID:24999557

  14. Measurement of SBS physics parameters. Final report

    SciTech Connect

    1995-12-31

    SBS characteristics of the KD{sup *}P crystals were determined by the method of SBS generation excitation in the transverse resonator. Fused silica was utilized as the test medium. Experimental oscillograms of Stokes pulses were processed by the method of pulse form approximation using the four-parametric function of time. The obtained SBS characteristics for these materials are in good agreement with the published literary data and the available theoretical presentation data.

  15. Control of cellular automata

    NASA Astrophysics Data System (ADS)

    Bagnoli, Franco; Rechtman, Raúl; El Yacoubi, Samira

    2012-12-01

    We study the problem of master-slave synchronization and control of totalistic cellular automata. The synchronization mechanism is that of setting a fraction of sites of the slave system equal to those of the master one (pinching synchronization). The synchronization observable is the distance between the two configurations. We present three control strategies that exploit local information (the number of nonzero first-order Boolean derivatives) in order to choose the sites to be synchronized. When no local information is used, we speak of simple pinching synchronization. We find the critical properties of control and discuss the best control strategy compared with simple synchronization.

  16. Formin’ cellular structures

    PubMed Central

    Bogdan, Sven; Schultz, Jörg; Grosshans, Jörg

    2014-01-01

    Members of the Diaphanous (Dia) protein family are key regulators of fundamental actin driven cellular processes, which are conserved from yeast to humans. Researchers have uncovered diverse physiological roles in cell morphology, cell motility, cell polarity, and cell division, which are involved in shaping cells into tissues and organs. The identification of numerous binding partners led to substantial progress in our understanding of the differential functions of Dia proteins. Genetic approaches and new microscopy techniques allow important new insights into their localization, activity, and molecular principles of regulation. PMID:24719676

  17. Cellular mechanics and motility

    NASA Astrophysics Data System (ADS)

    Hénon, Sylvie; Sykes, Cécile

    2015-10-01

    The term motility defines the movement of a living organism. One widely known example is the motility of sperm cells, or the one of flagellar bacteria. The propulsive element of such organisms is a cilium(or flagellum) that beats. Although cells in our tissues do not have a flagellum in general, they are still able to move, as we will discover in this chapter. In fact, in both cases of movement, with or without a flagellum, cell motility is due to a dynamic re-arrangement of polymers inside the cell. Let us first have a closer look at the propulsion mechanism in the case of a flagellum or a cilium, which is the best known, but also the simplest, and which will help us to define the hydrodynamic general conditions of cell movement. A flagellum is sustained by cellular polymers arranged in semi-flexible bundles and flagellar beating generates cell displacement. These polymers or filaments are part of the cellular skeleton, or "cytoskeleton", which is, in this case, external to the cellular main body of the organism. In fact, bacteria move in a hydrodynamic regime in which viscosity dominates over inertia. The system is thus in a hydrodynamic regime of low Reynolds number (Box 5.1), which is nearly exclusively the case in all cell movements. Bacteria and their propulsion mode by flagella beating are our unicellular ancestors 3.5 billion years ago. Since then, we have evolved to form pluricellular organisms. However, to keep the ability of displacement, to heal our wounds for example, our cells lost their flagellum, since it was not optimal in a dense cell environment: cells are too close to each other to leave enough space for the flagella to accomplish propulsion. The cytoskeleton thus developed inside the cell body to ensure cell shape changes and movement, and also mechanical strength within a tissue. The cytoskeleton of our cells, like the polymers or filaments that sustain the flagellum, is also composed of semi-flexible filaments arranged in bundles, and also in

  18. Cellular automata model for citrus variegated chlorosis.

    PubMed

    Martins, M L; Ceotto, G; Alves, S G; Bufon, C C; Silva, J M; Laranjeira, F F

    2000-11-01

    A cellular automata model is proposed to analyze the progress of citrus variegated chlorosis epidemics in São Paulo orange plantations. In this model epidemiological and environmental features, such as motility of sharpshooter vectors that perform Lévy flights, level of plant hydric and nutritional stress, and seasonal climatic effects, are included. The observed epidemic data were quantitatively reproduced by the proposed model on varying the parameters controlling vector motility, plant stress, and initial population of diseased plants. PMID:11102058

  19. Solid films and transports in cellular foams

    NASA Astrophysics Data System (ADS)

    Tan Hoang, Minh; Perrot, Camille

    2012-09-01

    We show that critical path ideas lead to the identification of two local characteristic sizes for the long wavelength acoustic properties in cellular solids, the pore and throat sizes. Application of the model to real foam samples, which may contain solid films or membranes yields quantitative agreement between a finite-element numerical homogenization approach and experimental results. From three routinely available laboratory measurements: the open porosity ϕ, the static viscous permeability k0, and the average struts length Lm obtained from microscopy analysis; asymptotic transport parameters at high-frequencies and the normal incidence sound absorption coefficient are derived with no adjustable parameters.

  20. Cellular Contraction and Polarization Drive Collective Cellular Motion.

    PubMed

    Notbohm, Jacob; Banerjee, Shiladitya; Utuje, Kazage J C; Gweon, Bomi; Jang, Hwanseok; Park, Yongdoo; Shin, Jennifer; Butler, James P; Fredberg, Jeffrey J; Marchetti, M Cristina

    2016-06-21

    Coordinated motions of close-packed multicellular systems typically generate cooperative packs, swirls, and clusters. These cooperative motions are driven by active cellular forces, but the physical nature of these forces and how they generate collective cellular motion remain poorly understood. Here, we study forces and motions in a confined epithelial monolayer and make two experimental observations: 1) the direction of local cellular motion deviates systematically from the direction of the local traction exerted by each cell upon its substrate; and 2) oscillating waves of cellular motion arise spontaneously. Based on these observations, we propose a theory that connects forces and motions using two internal state variables, one of which generates an effective cellular polarization, and the other, through contractile forces, an effective cellular inertia. In agreement with theoretical predictions, drugs that inhibit contractility reduce both the cellular effective elastic modulus and the frequency of oscillations. Together, theory and experiment provide evidence suggesting that collective cellular motion is driven by at least two internal variables that serve to sustain waves and to polarize local cellular traction in a direction that deviates systematically from local cellular velocity. PMID:27332131

  1. Cellular basis of memory for addiction.

    PubMed

    Nestler, Eric J

    2013-12-01

    DESPITE THE IMPORTANCE OF NUMEROUS PSYCHOSOCIAL FACTORS, AT ITS CORE, DRUG ADDICTION INVOLVES A BIOLOGICAL PROCESS: the ability of repeated exposure to a drug of abuse to induce changes in a vulnerable brain that drive the compulsive seeking and taking of drugs, and loss of control over drug use, that define a state of addiction. Here, we review the types of molecular and cellular adaptations that occur in specific brain regions to mediate addiction-associated behavioral abnormalities. These include alterations in gene expression achieved in part via epigenetic mechanisms, plasticity in the neurophysiological functioning of neurons and synapses, and associated plasticity in neuronal and synaptic morphology mediated in part by altered neurotrophic factor signaling. Each of these types of drug-induced modifications can be viewed as a form of "cellular or molecular memory." Moreover, it is striking that most addiction-related forms of plasticity are very similar to the types of plasticity that have been associated with more classic forms of "behavioral memory," perhaps reflecting the finite repertoire of adaptive mechanisms available to neurons when faced with environmental challenges. Finally, addiction-related molecular and cellular adaptations involve most of the same brain regions that mediate more classic forms of memory, consistent with the view that abnormal memories are important drivers of addiction syndromes. The goal of these studies which aim to explicate the molecular and cellular basis of drug addiction is to eventually develop biologically based diagnostic tests, as well as more effective treatments for addiction disorders. PMID:24459410

  2. Cellular Mechanisms Controlling Caspase Activation and Function

    PubMed Central

    Parrish, Amanda B.; Freel, Christopher D.; Kornbluth, Sally

    2013-01-01

    Caspases are the primary drivers of apoptotic cell death, cleaving cellular proteins that are critical for dismantling the dying cell. Initially translated as inactive zymogenic precursors, caspases are activated in response to a variety of cell death stimuli. In addition to factors required for their direct activation (e.g., dimerizing adaptor proteins in the case of initiator caspases that lie at the apex of apoptotic signaling cascades), caspases are regulated by a variety of cellular factors in a myriad of physiological and pathological settings. For example, caspases may be modified posttranslationally (e.g., by phosphorylation or ubiquitylation) or through interaction of modulatory factors with either the zymogenic or active form of a caspase, altering its activation and/or activity. These regulatory events may inhibit or enhance enzymatic activity or may affect activity toward particular cellular substrates. Finally, there is emerging literature to suggest that caspases can participate in a variety of cellular processes unrelated to apoptotic cell death. In these settings, it is particularly important that caspases are maintained under stringent control to avoid inadvertent cell death. It is likely that continued examination of these processes will reveal new mechanisms of caspase regulation with implications well beyond control of apoptotic cell death. PMID:23732469

  3. Integrated cellular systems

    NASA Astrophysics Data System (ADS)

    Harper, Jason C.

    The generation of new three-dimensional (3D) matrices that enable integration of biomolecular components and whole cells into device architectures, without adversely altering their morphology or activity, continues to be an expanding and challenging field of research. This research is driven by the promise that encapsulated biomolecules and cells can significantly impact areas as diverse as biocatalysis, controlled delivery of therapeutics, environmental and industrial process monitoring, early warning of warfare agents, bioelectronics, photonics, smart prosthetics, advanced physiological sensors, portable medical diagnostic devices, and tissue/organ replacement. This work focuses on the development of a fundamental understanding of the biochemical and nanomaterial mechanisms that govern the cell directed assembly and integration process. It was shown that this integration process relies on the ability of cells to actively develop a pH gradient in response to evaporation induced osmotic stress, which catalyzes silica condensation within a thin 3D volume surrounding the cells, creating a functional bio/nano interface. The mechanism responsible for introducing functional foreign membrane-bound proteins via proteoliposome addition to the silica-lipid-cell matrix was also determined. Utilizing this new understanding, 3D cellular immobilization capabilities were extended using sol-gel matrices endowed with glycerol, trehalose, and media components. The effects of these additives, and the metabolic phase of encapsulated S. cerivisiase cells, on long-term viability and the rate of inducible gene expression was studied. This enabled the entrapment of cells within a novel microfluidic platform capable of simultaneous colorimetric, fluorescent, and electrochemical detection of a single analyte, significantly improving confidence in the biosensor output. As a complementary approach, multiphoton protein lithography was utilized to engineer 3D protein matrices in which to

  4. Stochastic cellular automata model for wildland fire spread dynamics

    NASA Astrophysics Data System (ADS)

    Maduro Almeida, Rodolfo; Macau, Elbert E. N.

    2011-03-01

    A stochastic cellular automata model for wildland fire spread under flat terrain and no-wind conditions is proposed and its dynamics is characterized and analyzed. One of three possible states characterizes each cell: vegetation cell, burning cell and burnt cell. The dynamics of fire spread is modeled as a stochastic event with an effective fire spread probability S which is a function of three probabilities that characterize: the proportion of vegetation cells across the lattice, the probability of a burning cell becomes burnt, and the probability of the fire spread from a burning cell to a neighboring vegetation cell. A set of simulation experiments is performed to analyze the effects of different values of the three probabilities in the fire pattern. Monte-Carlo simulations indicate that there is a critical line in the model parameter space that separates the set of parameters which a fire can propagate from those for which it cannot propagate. Finally, the relevance of the model is discussed under the light of computational experiments that illustrate the capability of the model catches both the dynamical and static qualitative properties of fire propagation.

  5. Predicting and Analyzing Cellular Networks

    NASA Astrophysics Data System (ADS)

    Singh, Mona

    High-throughput experimental technologies, along with computational predictions, have resulted in large-scale biological networks for numerous organisms. Global analyses of biological networks provide new opportunities for revealing protein functions and pathways, and for uncovering cellular organization principles. In my talk, I will discuss a number of approaches we have developed over the years for the complementary problems of predicting interactions and analyzing interaction networks. First, I will describe a genomic approach for uncovering high-confidence regulatory interactions, and show how it can be effectively combined with a framework for predicting regulatory interactions for proteins with known structural domains but unknown binding specificity. Next, I will describe algorithms for analyzing protein interaction networks in order to uncover protein function and functional modules, and demonstrate the importance of considering the topological structure of interaction networks in order to make high quality predictions. Finally, I will present a framework for explicitly incorporating known attributes of individual proteins into the analysis of biological networks, and utilize it to discover recurring network patterns underlying a range of biological processes.

  6. Engineering Cellular Metabolism.

    PubMed

    Nielsen, Jens; Keasling, Jay D

    2016-03-10

    Metabolic engineering is the science of rewiring the metabolism of cells to enhance production of native metabolites or to endow cells with the ability to produce new products. The potential applications of such efforts are wide ranging, including the generation of fuels, chemicals, foods, feeds, and pharmaceuticals. However, making cells into efficient factories is challenging because cells have evolved robust metabolic networks with hard-wired, tightly regulated lines of communication between molecular pathways that resist efforts to divert resources. Here, we will review the current status and challenges of metabolic engineering and will discuss how new technologies can enable metabolic engineering to be scaled up to the industrial level, either by cutting off the lines of control for endogenous metabolism or by infiltrating the system with disruptive, heterologous pathways that overcome cellular regulation. PMID:26967285

  7. Cellular Morphogenesis In Silico

    PubMed Central

    Shinbrot, Troy; Chun, Young; Caicedo-Carvajal, Carlos; Foty, Ramsey

    2009-01-01

    Abstract We describe a model that simulates spherical cells of different types that can migrate and interact either attractively or repulsively. We find that both expected morphologies and previously unreported patterns spontaneously self-assemble. Among the newly discovered patterns are a segmented state of alternating discs, and a “shish-kebab” state, in which one cell type forms a ring around a second type. We show that these unique states result from cellular attraction that increases with distance (e.g., as membranes stretch viscoelastically), and would not be seen in traditional, e.g., molecular, potentials that diminish with distance. Most of the states found computationally have been observed in vitro, and it remains to be established what role these self-assembled states may play in in vivo morphogenesis. PMID:19686642

  8. Cellular and Molecular Mechanisms of AKI.

    PubMed

    Agarwal, Anupam; Dong, Zheng; Harris, Raymond; Murray, Patrick; Parikh, Samir M; Rosner, Mitchell H; Kellum, John A; Ronco, Claudio

    2016-05-01

    In this article, we review the current evidence for the cellular and molecular mechanisms of AKI, focusing on epithelial cell pathobiology and related cell-cell interactions, using ischemic AKI as a model. Highlighted are the clinical relevance of cellular and molecular targets that have been investigated in experimental models of ischemic AKI and how such models might be improved to optimize translation into successful clinical trials. In particular, development of more context-specific animal models with greater relevance to human AKI is urgently needed. Comorbidities that could alter patient susceptibility to AKI, such as underlying diabetes, aging, obesity, cancer, and CKD, should also be considered in developing these models. Finally, harmonization between academia and industry for more clinically relevant preclinical testing of potential therapeutic targets and better translational clinical trial design is also needed to achieve the goal of developing effective interventions for AKI. PMID:26860342

  9. SELF-ORGANIZED CRITICALITY AND CELLULAR AUTOMATA

    SciTech Connect

    CREUTZ,M.

    2007-01-01

    Cellular automata provide a fascinating class of dynamical systems based on very simple rules of evolution yet capable of displaying highly complex behavior. These include simplified models for many phenomena seen in nature. Among other things, they provide insight into self-organized criticality, wherein dissipative systems naturally drive themselves to a critical state with important phenomena occurring over a wide range of length and the scales. This article begins with an overview of self-organized criticality. This is followed by a discussion of a few examples of simple cellular automaton systems, some of which may exhibit critical behavior. Finally, some of the fascinating exact mathematical properties of the Bak-Tang-Wiesenfeld sand-pile model [1] are discussed.

  10. Active Degradation Explains the Distribution of Nuclear Proteins during Cellular Senescence

    PubMed Central

    Giampieri, Enrico; De Cecco, Marco; Remondini, Daniel; Sedivy, John; Castellani, Gastone

    2015-01-01

    The amount of cellular proteins is a crucial parameter that is known to vary between cells as a function of the replicative passages, and can be important during physiological aging. The process of protein degradation is known to be performed by a series of enzymatic reactions, ranging from an initial step of protein ubiquitination to their final fragmentation by the proteasome. In this paper we propose a stochastic dynamical model of nuclear proteins concentration resulting from a balance between a constant production of proteins and their degradation by a cooperative enzymatic reaction. The predictions of this model are compared with experimental data obtained by fluorescence measurements of the amount of nuclear proteins in murine tail fibroblast (MTF) undergoing cellular senescence. Our model provides a three-parameter stationary distribution that is in good agreement with the experimental data even during the transition to the senescent state, where the nuclear protein concentration changes abruptly. The estimation of three parameters (cooperativity, saturation threshold, and maximal velocity of the reaction), and their evolution during replicative passages shows that only the maximal velocity varies significantly. Based on our modeling we speculate the reduction of functionality of the protein degradation mechanism as a possible competitive inhibition of the proteasome. PMID:26115222

  11. From quantum cellular automata to quantum lattice gases

    SciTech Connect

    Meyer, D.A.

    1996-12-01

    A natural architecture for nanoscale quantum computation is that of a quantum cellular automaton. Motivated by this observation, we begin an investigation of exactly unitary cellular automata. After proving that there can be no nontrivial, homogeneous, local, unitary, scalar cellular automaton in one dimension, we weaken the homogeneity condition and show that there are nontrivial, exactly unitary, partitioning cellular automata. We find a one-parameter family of evolution rules which are best interpreted as those for a one-particle quantum automaton. This model is naturally reformulated as a two component cellular automaton which we demonstrate to limit to the Dirac equation. We describe two generalizations of this automaton, the second of which, to multiple interacting particles, is the correct definition of a quantum lattice gas.

  12. Electrosurgery with cellular precision.

    PubMed

    Palanker, Daniel V; Vankov, Alexander; Huie, Philip

    2008-02-01

    Electrosurgery, one of the most-often used surgical tools, is a robust but somewhat crude technology that has changed surprisingly little since its invention almost a century ago. Continuous radiofrequency is still used for tissue cutting, with thermal damage extending to hundreds of micrometers. In contrast, lasers developed 70 years later, have been constantly perfected, and the laser-tissue interactions explored in great detail, which has allowed tissue ablation with cellular precision in many laser applications. We discuss mechanisms of tissue damage by electric field, and demonstrate that electrosurgery with properly optimized waveforms and microelectrodes can rival many advanced lasers. Pulsed electric waveforms with burst durations ranging from 10 to 100 micros applied via insulated planar electrodes with 12 microm wide exposed edges produced plasma-mediated dissection of tissues with the collateral damage zone ranging from 2 to 10 microm. Length of the electrodes can vary from micrometers to centimeters and all types of soft tissues-from membranes to cartilage and skin could be dissected in liquid medium and in a dry field. This technology may allow for major improvements in outcomes of the current surgical procedures and development of much more refined surgical techniques. PMID:18270030

  13. Cellular energy metabolism

    SciTech Connect

    Glaser, M.

    1991-06-01

    Studies have been carried out on adenylate kinase which is an important enzyme in determining the concentrations of the adenine nucleotides. An efficient method has been developed to clone mutant adenylate kinase genes in E. coli. Site-specific mutagenesis of the wild type gene also has been used to obtain forms of adenylate kinase with altered amino acids. The wild type and mutant forms of adenylate kinase have been overexpressed and large quantities were readily isolated. The kinetic and fluorescence properties of the different forms of adenylate kinase were characterized. This has led to a new model for the location of the AMP and ATP bindings sites on the enzyme and a proposal for the mechanism of substrate inhibition. Crystals of the wild type enzyme were obtained that diffract to at least 2.3 {angstrom} resolution. Experiments were also initiated to determine the function of adenylate kinase in vivo. In one set of experiments, E. coli strains with mutations in adenylate kinase showed large changes in cellular nucleotides after reaching the stationary phase in a low phosphate medium. This was caused by selective proteolytic degradation of the mutant adenylate kinase caused by phosphate starvation.

  14. Molecular and Cellular Biophysics

    NASA Astrophysics Data System (ADS)

    Jackson, Meyer B.

    2006-01-01

    Molecular and Cellular Biophysics provides advanced undergraduate and graduate students with a foundation in the basic concepts of biophysics. Students who have taken physical chemistry and calculus courses will find this book an accessible and valuable aid in learning how these concepts can be used in biological research. The text provides a rigorous treatment of the fundamental theories in biophysics and illustrates their application with examples. Conformational transitions of proteins are studied first using thermodynamics, and subsequently with kinetics. Allosteric theory is developed as the synthesis of conformational transitions and association reactions. Basic ideas of thermodynamics and kinetics are applied to topics such as protein folding, enzyme catalysis and ion channel permeation. These concepts are then used as the building blocks in a treatment of membrane excitability. Through these examples, students will gain an understanding of the general importance and broad applicability of biophysical principles to biological problems. Offers a unique synthesis of concepts across a wide range of biophysical topics Provides a rigorous theoretical treatment, alongside applications in biological systems Author has been teaching biophysics for nearly 25 years

  15. 47 CFR 22.909 - Cellular markets.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Cellular markets. 22.909 Section 22.909... Cellular Radiotelephone Service § 22.909 Cellular markets. Cellular markets are standard geographic areas used by the FCC for administrative convenience in the licensing of cellular systems. Cellular...

  16. 47 CFR 22.909 - Cellular markets.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Cellular markets. 22.909 Section 22.909... Cellular Radiotelephone Service § 22.909 Cellular markets. Cellular markets are standard geographic areas used by the FCC for administrative convenience in the licensing of cellular systems. Cellular...

  17. Cellular Particle Dynamics simulation of biomechanical relaxation processes of multi-cellular systems

    NASA Astrophysics Data System (ADS)

    McCune, Matthew; Kosztin, Ioan

    2013-03-01

    Cellular Particle Dynamics (CPD) is a theoretical-computational-experimental framework for describing and predicting the time evolution of biomechanical relaxation processes of multi-cellular systems, such as fusion, sorting and compression. In CPD, cells are modeled as an ensemble of cellular particles (CPs) that interact via short range contact interactions, characterized by an attractive (adhesive interaction) and a repulsive (excluded volume interaction) component. The time evolution of the spatial conformation of the multicellular system is determined by following the trajectories of all CPs through numerical integration of their equations of motion. Here we present CPD simulation results for the fusion of both spherical and cylindrical multi-cellular aggregates. First, we calibrate the relevant CPD model parameters for a given cell type by comparing the CPD simulation results for the fusion of two spherical aggregates to the corresponding experimental results. Next, CPD simulations are used to predict the time evolution of the fusion of cylindrical aggregates. The latter is relevant for the formation of tubular multi-cellular structures (i.e., primitive blood vessels) created by the novel bioprinting technology. Work supported by NSF [PHY-0957914]. Computer time provided by the University of Missouri Bioinformatics Consortium.

  18. A model for the volumetric radiation characteristics of cellular ceramics

    SciTech Connect

    Fu, X.; Viskanta, R.; Gore, J.P.

    1997-12-01

    A unit cell based model for cellular ceramics was developed in conjunction with the discrete ordinates method for radiative transfer to predict theoretically the effective volumetric radiation characteristics of the cellular ceramics. Model input parameters include the porosity, pores per centimeter (PPC) and reflectivity of the solid material. Numerical calculations of the extinction coefficients and single scattering albedo are reported over the range of reflectivities from 0 to 1, porosities from 0.6 to 0.95 and PPC from 4 to 26. A comparison between model predictions and spectral emittance data for cellular ceramics reported in the literature shows agreement within 5 to 10% which is within experimental uncertainty.

  19. Cellular and physical mechanisms of branching morphogenesis

    PubMed Central

    Varner, Victor D.; Nelson, Celeste M.

    2014-01-01

    Branching morphogenesis is the developmental program that builds the ramified epithelial trees of various organs, including the airways of the lung, the collecting ducts of the kidney, and the ducts of the mammary and salivary glands. Even though the final geometries of epithelial trees are distinct, the molecular signaling pathways that control branching morphogenesis appear to be conserved across organs and species. However, despite this molecular homology, recent advances in cell lineage analysis and real-time imaging have uncovered surprising differences in the mechanisms that build these diverse tissues. Here, we review these studies and discuss the cellular and physical mechanisms that can contribute to branching morphogenesis. PMID:25005470

  20. Gas Transfer in Cellularized Collagen-Membrane Gas Exchange Devices

    PubMed Central

    Lo, Justin H.; Bassett, Erik K.; Penson, Elliot J. N.; Hoganson, David M.

    2015-01-01

    Chronic lower respiratory disease is highly prevalent in the United States, and there remains a need for alternatives to lung transplant for patients who progress to end-stage lung disease. Portable or implantable gas oxygenators based on microfluidic technologies can address this need, provided they operate both efficiently and biocompatibly. Incorporating biomimetic materials into such devices can help replicate native gas exchange function and additionally support cellular components. In this work, we have developed microfluidic devices that enable blood gas exchange across ultra-thin collagen membranes (as thin as 2 μm). Endothelial, stromal, and parenchymal cells readily adhere to these membranes, and long-term culture with cellular components results in remodeling, reflected by reduced membrane thickness. Functionally, acellular collagen-membrane lung devices can mediate effective gas exchange up to ∼288 mL/min/m2 of oxygen and ∼685 mL/min/m2 of carbon dioxide, approaching the gas exchange efficiency noted in the native lung. Testing several configurations of lung devices to explore various physical parameters of the device design, we concluded that thinner membranes and longer gas exchange distances result in improved hemoglobin saturation and increases in pO2. However, in the design space tested, these effects are relatively small compared to the improvement in overall oxygen and carbon dioxide transfer by increasing the blood flow rate. Finally, devices cultured with endothelial and parenchymal cells achieved similar gas exchange rates compared with acellular devices. Biomimetic blood oxygenator design opens the possibility of creating portable or implantable microfluidic devices that achieve efficient gas transfer while also maintaining physiologic conditions. PMID:26020102

  1. Integrated segmentation of cellular structures

    NASA Astrophysics Data System (ADS)

    Ajemba, Peter; Al-Kofahi, Yousef; Scott, Richard; Donovan, Michael; Fernandez, Gerardo

    2011-03-01

    Automatic segmentation of cellular structures is an essential step in image cytology and histology. Despite substantial progress, better automation and improvements in accuracy and adaptability to novel applications are needed. In applications utilizing multi-channel immuno-fluorescence images, challenges include misclassification of epithelial and stromal nuclei, irregular nuclei and cytoplasm boundaries, and over and under-segmentation of clustered nuclei. Variations in image acquisition conditions and artifacts from nuclei and cytoplasm images often confound existing algorithms in practice. In this paper, we present a robust and accurate algorithm for jointly segmenting cell nuclei and cytoplasm using a combination of ideas to reduce the aforementioned problems. First, an adaptive process that includes top-hat filtering, Eigenvalues-of-Hessian blob detection and distance transforms is used to estimate the inverse illumination field and correct for intensity non-uniformity in the nuclei channel. Next, a minimum-error-thresholding based binarization process and seed-detection combining Laplacian-of-Gaussian filtering constrained by a distance-map-based scale selection is used to identify candidate seeds for nuclei segmentation. The initial segmentation using a local maximum clustering algorithm is refined using a minimum-error-thresholding technique. Final refinements include an artifact removal process specifically targeted at lumens and other problematic structures and a systemic decision process to reclassify nuclei objects near the cytoplasm boundary as epithelial or stromal. Segmentation results were evaluated using 48 realistic phantom images with known ground-truth. The overall segmentation accuracy exceeds 94%. The algorithm was further tested on 981 images of actual prostate cancer tissue. The artifact removal process worked in 90% of cases. The algorithm has now been deployed in a high-volume histology analysis application.

  2. MSAT and cellular hybrid networking

    NASA Technical Reports Server (NTRS)

    Baranowsky, Patrick W., II

    1993-01-01

    Westinghouse Electric Corporation is developing both the Communications Ground Segment and the Series 1000 Mobile Phone for American Mobile Satellite Corporation's (AMSC's) Mobile Satellite (MSAT) system. The success of the voice services portion of this system depends, to some extent, upon the interoperability of the cellular network and the satellite communication circuit switched communication channels. This paper will describe the set of user-selectable cellular interoperable modes (cellular first/satellite second, etc.) provided by the Mobile Phone and described how they are implemented with the ground segment. Topics including roaming registration and cellular-to-satellite 'seamless' call handoff will be discussed, along with the relevant Interim Standard IS-41 Revision B Cellular Radiotelecommunications Intersystem Operations and IOS-553 Mobile Station - Land Station Compatibility Specification.

  3. Astrobiological complexity with probabilistic cellular automata.

    PubMed

    Vukotić, Branislav; Ćirković, Milan M

    2012-08-01

    The search for extraterrestrial life and intelligence constitutes one of the major endeavors in science, but has yet been quantitatively modeled only rarely and in a cursory and superficial fashion. We argue that probabilistic cellular automata (PCA) represent the best quantitative framework for modeling the astrobiological history of the Milky Way and its Galactic Habitable Zone. The relevant astrobiological parameters are to be modeled as the elements of the input probability matrix for the PCA kernel. With the underlying simplicity of the cellular automata constructs, this approach enables a quick analysis of large and ambiguous space of the input parameters. We perform a simple clustering analysis of typical astrobiological histories with "Copernican" choice of input parameters and discuss the relevant boundary conditions of practical importance for planning and guiding empirical astrobiological and SETI projects. In addition to showing how the present framework is adaptable to more complex situations and updated observational databases from current and near-future space missions, we demonstrate how numerical results could offer a cautious rationale for continuation of practical SETI searches. PMID:22832998

  4. Astrobiological Complexity with Probabilistic Cellular Automata

    NASA Astrophysics Data System (ADS)

    Vukotić, Branislav; Ćirković, Milan M.

    2012-08-01

    The search for extraterrestrial life and intelligence constitutes one of the major endeavors in science, but has yet been quantitatively modeled only rarely and in a cursory and superficial fashion. We argue that probabilistic cellular automata (PCA) represent the best quantitative framework for modeling the astrobiological history of the Milky Way and its Galactic Habitable Zone. The relevant astrobiological parameters are to be modeled as the elements of the input probability matrix for the PCA kernel. With the underlying simplicity of the cellular automata constructs, this approach enables a quick analysis of large and ambiguous space of the input parameters. We perform a simple clustering analysis of typical astrobiological histories with "Copernican" choice of input parameters and discuss the relevant boundary conditions of practical importance for planning and guiding empirical astrobiological and SETI projects. In addition to showing how the present framework is adaptable to more complex situations and updated observational databases from current and near-future space missions, we demonstrate how numerical results could offer a cautious rationale for continuation of practical SETI searches.

  5. Leucocyte cellular adhesion molecules.

    PubMed

    Yong, K; Khwaja, A

    1990-12-01

    Leucocytes express adhesion promoting receptors which mediate cell-cell and cell-matrix interactions. These adhesive interactions are crucial to the regulation of haemopoiesis and thymocyte maturation, the direction and control of leucocyte traffic and migration through tissues, and in the development of immune and non-immune inflammatory responses. Several families of adhesion receptors have been identified (Table). The leucocyte integrin family comprises 3 alpha beta heterodimeric membrane glycoproteins which share a common beta subunit, designated CD18. The alpha subunits of each of the 3 members, lymphocyte function associated antigen-1 (LFA-1), macrophage antigen-1 (Mac-1) and p150,95 are designated CD11a, b and c respectively. These adhesion molecules play a critical part in the immune and inflammatory responses of leucocytes. The leucocyte integrin family is, in turn, part of the integrin superfamily, members of which are evolutionally, structurally and functionally related. Another Integrin subfamily found on leucocytes is the VLA group, so-called because the 'very late activation antigens' VLA-1 and VLA-2 were originally found to appear late in T-cell activation. Members of this family function mainly as extracellular matrix adhesion receptors and are found both on haemopoietic and non-haemopoietic cells. They play a part in diverse cellular functions including tissue organisation, lymphocyte recirculation and T-cell immune responses. A third integrin subfamily, the cytoadhesins, are receptors on platelets and endothelial cells which bind extracellular matrix proteins. A second family of adhesion receptors is the immunoglobulin superfamily, members of which include CD2, LFA-3 and ICAM-1, which participate in T-cell adhesive interactions, and the antigen-specific receptors of T and B cells, CD4, CD8 and the MHC Class I and II molecules. A recently recognised family of adhesion receptors is the selectins, characterised by a common lectin domain. Leucocyte

  6. Cellular basis of memory for addiction

    PubMed Central

    Nestler, Eric J.

    2013-01-01

    Despite the importance of numerous psychosocial factors, at its core, drug addiction involves a biological process: the ability of repeated exposure to a drug of abuse to induce changes in a vulnerable brain that drive the compulsive seeking and taking of drugs, and loss of control over drug use, that define a state of addiction. Here, we review the types of molecular and cellular adaptations that occur in specific brain regions to mediate addiction-associated behavioral abnormalities. These include alterations in gene expression achieved in part via epigenetic mechanisms, plasticity in the neurophysiological functioning of neurons and synapses, and associated plasticity in neuronal and synaptic morphology mediated in part by altered neurotrophic factor signaling. Each of these types of drug-induced modifications can be viewed as a form of “cellular or molecular memory.” Moreover, it is striking that most addiction-related forms of plasticity are very similar to the types of plasticity that have been associated with more classic forms of “behavioral memory,” perhaps reflecting the finite repertoire of adaptive mechanisms available to neurons when faced with environmental challenges. Finally, addiction-related molecular and cellular adaptations involve most of the same brain regions that mediate more classic forms of memory, consistent with the view that abnormal memories are important drivers of addiction syndromes. The goal of these studies which aim to explicate the molecular and cellular basis of drug addiction is to eventually develop biologically based diagnostic tests, as well as more effective treatments for addiction disorders. PMID:24459410

  7. Taming the sphinx: Mechanisms of cellular sphingolipid homeostasis.

    PubMed

    Olson, D K; Fröhlich, F; Farese, R V; Walther, T C

    2016-08-01

    Sphingolipids are important structural membrane components of eukaryotic cells, and potent signaling molecules. As such, their levels must be maintained to optimize cellular functions in different cellular membranes. Here, we review the current knowledge of homeostatic sphingolipid regulation. We describe recent studies in Saccharomyces cerevisiae that have provided insights into how cells sense changes in sphingolipid levels in the plasma membrane and acutely regulate sphingolipid biosynthesis by altering signaling pathways. We also discuss how cellular trafficking has emerged as an important determinant of sphingolipid homeostasis. Finally, we highlight areas where work is still needed to elucidate the mechanisms of sphingolipid regulation and the physiological functions of such regulatory networks, especially in mammalian cells. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon. PMID:26747648

  8. Cellular compartmentalization of secondary metabolism

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fungal secondary metabolism is often considered apart from the essential housekeeping functions of the cell. However, there are clear links between fundamental cellular metabolism and the biochemical pathways leading to secondary metabolite synthesis. Besides utilizing key biochemical precursors sh...

  9. Cellular therapy for haematological malignancies.

    PubMed

    Roddie, P H; Turner, M L

    2002-11-01

    The aim of this review was to summarize the recent progress made in the field of cellular therapeutics in haematological malignancy. The review also examined the role that the National Transfusion Services might play in the manufacture of new cellular therapeutic agents, given both their expertise in the safe provision of blood products and their possession of accredited cell manipulation facilities. Cellular therapy is entering an era in which novel cellular products will find increasing clinical use, particularly in the areas of haematopoietic stem cell transplantation and immunotherapy. The production of novel cell-based therapies, both in Europe and North America, is now under strict regulatory control and therefore collaboration with the National Transfusion Services in the manufacture of these agents may well be beneficial if the production standards demanded by the regulatory authorities are to be fulfilled. PMID:12437515

  10. A magnetically actuated cellular strain assessment tool for quantitative analysis of strain induced cellular reorientation and actin alignment

    NASA Astrophysics Data System (ADS)

    Khademolhosseini, F.; Liu, C.-C.; Lim, C. J.; Chiao, M.

    2016-08-01

    Commercially available cell strain tools, such as pneumatically actuated elastomer substrates, require special culture plates, pumps, and incubator setups. In this work, we present a magnetically actuated cellular strain assessment tool (MACSAT) that can be implemented using off-the-shelf components and conventional incubators. We determine the strain field on the MACSAT elastomer substrate using numerical models and experimental measurements and show that a specific region of the elastomer substrate undergoes a quasi-uniaxial 2D stretch, and that cells confined to this region of the MACSAT elastomer substrate undergo tensile, compressive, or zero axial strain depending on their angle of orientation. Using the MACSAT to apply cyclic strain on endothelial cells, we demonstrate that actin filaments within the cells reorient away from the stretching direction, towards the directions of minimum axial strain. We show that the final actin orientation angles in strained cells are spread over a region of compressive axial strain, confirming previous findings on the existence of a varied pre-tension in the actin filaments of the cytoskeleton. We also demonstrate that strained cells exhibit distinctly different values of actin alignment coherency compared to unstrained cells and therefore propose that this parameter, i.e., the coherency of actin alignment, can be used as a new readout to determine the occurrence/extent of actin alignment in cell strain experiments. The tools and methods demonstrated in this study are simple and accessible and can be easily replicated by other researchers to study the strain response of other adherent cells.

  11. Spatial game in cellular automaton evacuation model

    NASA Astrophysics Data System (ADS)

    von Schantz, Anton; Ehtamo, Harri

    2015-11-01

    For numerical simulations of crowd dynamics in an evacuation we need a computationally light environment, such as the cellular automaton model (CA). By choosing the right model parameters, different types of crowd behavior and collective effects can be produced. But the CA does not answer why, when, and how these different behaviors and collective effects occur. In this article, we present a model, where we couple a spatial evacuation game to the CA. In the game, an agent chooses its strategy by observing its neighbors' strategies. The game matrix changes with the distance to the exit as the evacuation conditions develop. In the resulting model, an agent's strategy choice alters the parameters that govern its behavior in the CA. Thus, with our model, we are able to simulate how evacuation conditions affect the behavior of the crowd. Also, we show that some of the collective effects observed in evacuations are a result of the simple game the agents play.

  12. Mathematical Modeling of Cellular Metabolism.

    PubMed

    Berndt, Nikolaus; Holzhütter, Hermann-Georg

    2016-01-01

    Cellular metabolism basically consists of the conversion of chemical compounds taken up from the extracellular environment into energy (conserved in energy-rich bonds of organic phosphates) and a wide array of organic molecules serving as catalysts (enzymes), information carriers (nucleic acids), and building blocks for cellular structures such as membranes or ribosomes. Metabolic modeling aims at the construction of mathematical representations of the cellular metabolism that can be used to calculate the concentration of cellular molecules and the rates of their mutual chemical interconversion in response to varying external conditions as, for example, hormonal stimuli or supply of essential nutrients. Based on such calculations, it is possible to quantify complex cellular functions as cellular growth, detoxification of drugs and xenobiotic compounds or synthesis of exported molecules. Depending on the specific questions to metabolism addressed, the methodological expertise of the researcher, and available experimental information, different conceptual frameworks have been established, allowing the usage of computational methods to condense experimental information from various layers of organization into (self-) consistent models. Here, we briefly outline the main conceptual frameworks that are currently exploited in metabolism research. PMID:27557541

  13. Sound attenuation characteristics of cellular metamaterials

    NASA Astrophysics Data System (ADS)

    Varanasi, Satya Surya Srinivas

    could be mitigated by the addition of appropriate treatments such as a lightweight grid that modified the incident sound field to be normally directed. Although the performance of the metamaterial-based barrier solutions was better compared to the conventional ones, the performance can be poor at the system eigenfrequencies. The possibility of shifting energy from the deficit bands to other regions where the barriers are more efficient was numerically explored for embodiments of segmented cellular materials having non-linear stiffness characteristics. The acoustical behavior of such materials was probed through representative two-dimensional models of a segmented plate with a contact interface. Super-harmonic response peaks were observed for pure harmonic excitations, the strength of which were found to strongly depend on the degree of non-linearity or bilinear stiffness ratio. The closer an excitation frequency was to the characteristic eigenfrequencies of the structure, the stronger was the super-harmonic response, which supported the idea of transferring energy from problematic frequency bands to higher frequencies. Finally, the possibility of a spatial-shift of energy from longitudinal to lateral direction was explored with the idea of eliminating the design constraints associated with conventional absorbing materials, and with the hope of realizing a compact sound absorber. The embodiment was a two-phase chiral composite made using a Topologically Interlocked Material (TIM) with its unit cell being a tetrahedron consisting of two helicoid dissections. A comparative study was conducted with standard microstructures inspired by the Voigt and Reuss models. The twist mode of the chiral composites was found to be excited by an incident sound field normal to the plane of the TIM assembly. Although this behavior is not unique to a chiral microstructure, many other microstructures do not exhibit this behavior. The excitation of the twist mode by the incident sound field

  14. Aircraft parameter estimation

    NASA Technical Reports Server (NTRS)

    Iliff, Kenneth W.

    1987-01-01

    The aircraft parameter estimation problem is used to illustrate the utility of parameter estimation, which applies to many engineering and scientific fields. Maximum likelihood estimation has been used to extract stability and control derivatives from flight data for many years. This paper presents some of the basic concepts of aircraft parameter estimation and briefly surveys the literature in the field. The maximum likelihood estimator is discussed, and the basic concepts of minimization and estimation are examined for a simple simulated aircraft example. The cost functions that are to be minimized during estimation are defined and discussed. Graphic representations of the cost functions are given to illustrate the minimization process. Finally, the basic concepts are generalized, and estimation from flight data is discussed. Some of the major conclusions for the simulated example are also developed for the analysis of flight data from the F-14, highly maneuverable aircraft technology (HiMAT), and space shuttle vehicles.

  15. Target parameter estimation

    NASA Technical Reports Server (NTRS)

    Hocking, W. K.

    1989-01-01

    The objective of any radar experiment is to determine as much as possible about the entities which scatter the radiation. This review discusses many of the various parameters which can be deduced in a radar experiment, and also critically examines the procedures used to deduce them. Methods for determining the mean wind velocity, the RMS fluctuating velocities, turbulence parameters, and the shapes of the scatterers are considered. Complications with these determinations are discussed. It is seen throughout that a detailed understanding of the shape and cause of the scatterers is important in order to make better determinations of these various quantities. Finally, some other parameters, which are less easily acquired, are considered. For example, it is noted that momentum fluxes due to buoyancy waves and turbulence can be determined, and on occasions radars can be used to determine stratospheric diffusion coefficients and even temperature profiles in the atmosphere.

  16. Synchronization of One-Dimensional Stochastically Coupled Cellular Automata

    NASA Astrophysics Data System (ADS)

    Mrowinski, Maciej J.; Kosinski, Robert A.

    In this work the authors study synchronization resulting from the asymmetric stochastic coupling between two one-dimensional chaotic cellular automata and provide a simple analytical model to explain this phenomenon. The authors also study synchronization in a more general case, using sets of rules with a different number of states and different values of Langton's parameter λ.

  17. A Nucleator Arms Race: Cellular Control of Actin Assembly

    PubMed Central

    Campellone, Kenneth G.; Welch, Matthew D.

    2010-01-01

    For more than a decade the Arp2/3 complex, a handful of nucleation-promoting factors, and formins were the only molecules known to directly nucleate actin filament formation de novo. However, the past several years have brought a surge in the discovery of mammalian proteins with roles in actin nucleation and dynamics. Newly recognized nucleation-promoting factors, such as WASH, WHAMM, and JMY stimulate Arp2/3 complex activity at distinct cellular locations. Formin nucleators with additional biochemical and cellular activities have also been uncovered. Finally, the Spire, Cordon-bleu, and Leiomodin nucleators have revealed new ways of overcoming the kinetic barriers to actin polymerization. PMID:20237478

  18. Aging, Cellular Senescence, and Cancer

    PubMed Central

    Campisi, Judith

    2014-01-01

    For most species, aging promotes a host of degenerative pathologies that are characterized by debilitating losses of tissue or cellular function. However, especially among vertebrates, aging also promotes hyperplastic pathologies, the most deadly of which is cancer. In contrast to the loss of function that characterizes degenerating cells and tissues, malignant (cancerous) cells must acquire new (albeit aberrant) functions that allow them to develop into a lethal tumor. This review discusses the idea that, despite seemingly opposite characteristics, the degenerative and hyperplastic pathologies of aging are at least partly linked by a common biological phenomenon: a cellular stress response known as cellular senescence. The senescence response is widely recognized as a potent tumor suppressive mechanism. However, recent evidence strengthens the idea that it also drives both degenerative and hyper-plastic pathologies, most likely by promoting chronic inflammation. Thus, the senescence response may be the result of antagonistically pleiotropic gene action. PMID:23140366

  19. Aging, cellular senescence, and cancer.

    PubMed

    Campisi, Judith

    2013-01-01

    For most species, aging promotes a host of degenerative pathologies that are characterized by debilitating losses of tissue or cellular function. However, especially among vertebrates, aging also promotes hyperplastic pathologies, the most deadly of which is cancer. In contrast to the loss of function that characterizes degenerating cells and tissues, malignant (cancerous) cells must acquire new (albeit aberrant) functions that allow them to develop into a lethal tumor. This review discusses the idea that, despite seemingly opposite characteristics, the degenerative and hyperplastic pathologies of aging are at least partly linked by a common biological phenomenon: a cellular stress response known as cellular senescence. The senescence response is widely recognized as a potent tumor suppressive mechanism. However, recent evidence strengthens the idea that it also drives both degenerative and hyperplastic pathologies, most likely by promoting chronic inflammation. Thus, the senescence response may be the result of antagonistically pleiotropic gene action. PMID:23140366

  20. Cellular-based preemption system

    NASA Technical Reports Server (NTRS)

    Bachelder, Aaron D. (Inventor)

    2011-01-01

    A cellular-based preemption system that uses existing cellular infrastructure to transmit preemption related data to allow safe passage of emergency vehicles through one or more intersections. A cellular unit in an emergency vehicle is used to generate position reports that are transmitted to the one or more intersections during an emergency response. Based on this position data, the one or more intersections calculate an estimated time of arrival (ETA) of the emergency vehicle, and transmit preemption commands to traffic signals at the intersections based on the calculated ETA. Additional techniques may be used for refining the position reports, ETA calculations, and the like. Such techniques include, without limitation, statistical preemption, map-matching, dead-reckoning, augmented navigation, and/or preemption optimization techniques, all of which are described in further detail in the above-referenced patent applications.

  1. Fracture mechanics of cellular glass

    NASA Technical Reports Server (NTRS)

    Zwissler, J. G.; Adams, M. A.

    1981-01-01

    The fracture mechanics of cellular glasses (for the structural substrate of mirrored glass for solr concentrator reflecting panels) are discussed. Commercial and developmental cellular glasses were tested and analyzed using standard testing techniques and models developed from linear fracture mechanics. Two models describing the fracture behavior of these materials were developed. Slow crack growth behavior in cellular glass was found to be more complex than that encountered in dense glasses or ceramics. The crack velocity was found to be strongly dependent upon water vapor transport to the tip of the moving crack. The existence of a static fatigue limit was not conclusively established, however, it is speculated that slow crack growth behavior in Region 1 may be slower, by orders of magnitude, than that found in dense glasses.

  2. Genetic Algorithm Calibration of Probabilistic Cellular Automata for Modeling Mining Permit Activity

    USGS Publications Warehouse

    Louis, S.J.; Raines, G.L.

    2003-01-01

    We use a genetic algorithm to calibrate a spatially and temporally resolved cellular automata to model mining activity on public land in Idaho and western Montana. The genetic algorithm searches through a space of transition rule parameters of a two dimensional cellular automata model to find rule parameters that fit observed mining activity data. Previous work by one of the authors in calibrating the cellular automaton took weeks - the genetic algorithm takes a day and produces rules leading to about the same (or better) fit to observed data. These preliminary results indicate that genetic algorithms are a viable tool in calibrating cellular automata for this application. Experience gained during the calibration of this cellular automata suggests that mineral resource information is a critical factor in the quality of the results. With automated calibration, further refinements of how the mineral-resource information is provided to the cellular automaton will probably improve our model.

  3. Cellular senescence in aging primates.

    PubMed

    Herbig, Utz; Ferreira, Mark; Condel, Laura; Carey, Dee; Sedivy, John M

    2006-03-01

    The aging of organisms is characterized by a gradual functional decline of all organ systems. Mammalian somatic cells in culture display a limited proliferative life span, at the end of which they undergo an irreversible cell cycle arrest known as replicative senescence. Whether cellular senescence contributes to organismal aging has been controversial. We investigated telomere dysfunction, a recently discovered biomarker of cellular senescence, and found that the number of senescent fibroblasts increases exponentially in the skin of aging baboons, reaching >15% of all cells in very old individuals. In addition, the same cells contain activated ataxia-telangiectasia mutated kinase and heterochromatinized nuclei, confirming their senescent status. PMID:16456035

  4. Cellular basis of Alzheimer's disease.

    PubMed

    Bali, Jitin; Halima, Saoussen Ben; Felmy, Boas; Goodger, Zoe; Zurbriggen, Sebastian; Rajendran, Lawrence

    2010-12-01

    Alzheimer's disease (AD) is the most common form of neurodegenerative disease. A characteristic feature of the disease is the presence of amyloid-β (Aβ) which either in its soluble oligomeric form or in the plaque-associated form is causally linked to neurodegeneration. Aβ peptide is liberated from the membrane-spanning -amyloid precursor protein by sequential proteolytic processing employing β- and γ-secretases. All these proteins involved in the production of Aβ peptide are membrane associated and hence, membrane trafficking and cellular compartmentalization play important roles. In this review, we summarize the key cellular events that lead to the progression of AD. PMID:21369424

  5. Synthetic biology in cellular immunotherapy

    PubMed Central

    Chakravarti, Deboki; Wong, Wilson W.

    2015-01-01

    The adoptive transfer of genetically engineered T cells with cancer-targeting receptors has shown tremendous promise for eradicating tumors in clinical trials. This form of cellular immunotherapy presents a unique opportunity to incorporate advanced systems and synthetic biology approaches to create cancer therapeutics with novel functions. Here, we first review the development of synthetic receptors, switches, and circuits to control the location, duration, and strength of T cell activity against tumors. In addition, we discuss the cellular engineering and genome editing of host cells (or the chassis) to improve the efficacy of cell-based cancer therapeutics, and to reduce the time and cost of manufacturing. PMID:26088008

  6. Global properties of cellular automata

    SciTech Connect

    Jen, E.

    1986-04-01

    Cellular automata are discrete mathematical systems that generate diverse, often complicated, behavior using simple deterministic rules. Analysis of the local structure of these rules makes possible a description of the global properties of the associated automata. A class of cellular automata that generate infinitely many aperoidic temporal sequences is defined,a s is the set of rules for which inverses exist. Necessary and sufficient conditions are derived characterizing the classes of ''nearest-neighbor'' rules for which arbitrary finite initial conditions (i) evolve to a homogeneous state; (ii) generate at least one constant temporal sequence.

  7. Adaptive stochastic cellular automata: Applications

    NASA Astrophysics Data System (ADS)

    Qian, S.; Lee, Y. C.; Jones, R. D.; Barnes, C. W.; Flake, G. W.; O'Rourke, M. K.; Lee, K.; Chen, H. H.; Sun, G. Z.; Zhang, Y. Q.; Chen, D.; Giles, C. L.

    1990-09-01

    The stochastic learning cellular automata model has been applied to the problem of controlling unstable systems. Two example unstable systems studied are controlled by an adaptive stochastic cellular automata algorithm with an adaptive critic. The reinforcement learning algorithm and the architecture of the stochastic CA controller are presented. Learning to balance a single pole is discussed in detail. Balancing an inverted double pendulum highlights the power of the stochastic CA approach. The stochastic CA model is compared to conventional adaptive control and artificial neural network approaches.

  8. MINOR PARAMETERS NEEDED FOR INDIVIDUAL-DOSE CALCULATIONS: Final Report for Tasks 7.1, 7.2, 8.1, 8.2, 9.1, 9.2, and 9.3

    SciTech Connect

    Anspaugh, L. R.; Napier, Bruce A.

    2009-10-23

    This brief report documents the selection of parameters needed to support individual-dose calculations from 131I released into the environment with gaseous effluents from the Mayak Production Association.

  9. Cellular commitment in the developing cerebellum

    PubMed Central

    Marzban, Hassan; Del Bigio, Marc R.; Alizadeh, Javad; Ghavami, Saeid; Zachariah, Robby M.; Rastegar, Mojgan

    2014-01-01

    The mammalian cerebellum is located in the posterior cranial fossa and is critical for motor coordination and non-motor functions including cognitive and emotional processes. The anatomical structure of cerebellum is distinct with a three-layered cortex. During development, neurogenesis and fate decisions of cerebellar primordium cells are orchestrated through tightly controlled molecular events involving multiple genetic pathways. In this review, we will highlight the anatomical structure of human and mouse cerebellum, the cellular composition of developing cerebellum, and the underlying gene expression programs involved in cell fate commitments in the cerebellum. A critical evaluation of the cell death literature suggests that apoptosis occurs in ~5% of cerebellar cells, most shortly after mitosis. Apoptosis and cellular autophagy likely play significant roles in cerebellar development, we provide a comprehensive discussion of their role in cerebellar development and organization. We also address the possible function of unfolded protein response in regulation of cerebellar neurogenesis. We discuss recent advancements in understanding the epigenetic signature of cerebellar compartments and possible connections between DNA methylation, microRNAs and cerebellar neurodegeneration. Finally, we discuss genetic diseases associated with cerebellar dysfunction and their role in the aging cerebellum. PMID:25628535

  10. Single-Molecule Imaging of Cellular Signaling

    NASA Astrophysics Data System (ADS)

    De Keijzer, Sandra; Snaar-Jagalska, B. Ewa; Spaink, Herman P.; Schmidt, Thomas

    Single-molecule microscopy is an emerging technique to understand the function of a protein in the context of its natural environment. In our laboratory this technique has been used to study the dynamics of signal transduction in vivo. A multitude of signal transduction cascades are initiated by interactions between proteins in the plasma membrane. These cascades start by binding a ligand to its receptor, thereby activating downstream signaling pathways which finally result in complex cellular responses. To fully understand these processes it is important to study the initial steps of the signaling cascades. Standard biological assays mostly call for overexpression of the proteins and high concentrations of ligand. This sets severe limits to the interpretation of, for instance, the time-course of the observations, given the large temporal spread caused by the diffusion-limited binding processes. Methods and limitations of single-molecule microscopy for the study of cell signaling are discussed on the example of the chemotactic signaling of the slime-mold Dictyostelium discoideum. Single-molecule studies, as reviewed in this chapter, appear to be one of the essential methodologies for the full spatiotemporal clarification of cellular signaling, one of the ultimate goals in cell biology.

  11. Janus magnetic cellular spheroids for vascular tissue engineering

    PubMed Central

    Mattix, Brandon M.; Olsen, Timothy R.; Casco, Megan; Reese, Laura; Poole, John T.; Zhang, Jing; Visconti, Richard P.; Simionescu, Agneta; Simionescu, Dan T.; Alexis, Frank

    2016-01-01

    Cell aggregates, or spheroids, have been used as building blocks to fabricate scaffold-free tissues that can closely mimic the native three-dimensional in vivo environment for broad applications including regenerative medicine and high throughput testing of drugs. The incorporation of magnetic nanoparticles (MNPs) into spheroids permits the manipulation of spheroids into desired shapes, patterns, and tissues using magnetic forces. Current strategies incorporating MNPs often involve cellular uptake, and should therefore be avoided because it induces adverse effects on cell activity, viability, and phenotype. Here, we report a Janus structure of magnetic cellular spheroids (JMCS) with spatial control of MNPs to form two distinct domains: cells and extracellular MNPs. This separation of cells and MNPs within magnetic cellular spheroids was successfully incorporated into cellular spheroids with various cellular and extracellular compositions and contents. The amount of cells that internalized MNPs was quantified and showed that JMCSs resulted in significantly lower internalization (35%) compared to uptake spheroids (83%, p < 0.05). Furthermore, the addition of MNPs to cellular spheroids using the Janus method has no adverse effects on cellular viability up to seven weeks, with spheroids maintaining at least 82% viability over 7 weeks when compared to control spheroids without MNPs. By safely incorporating MNPs into cellular spheroids, results demonstrated that JMCSs were capable of magnetic manipulation, and that magnetic forces used during magnetic force assembly mediate fusion into controlled patterns and complex tissues. Finally, JMCSs were assembled and fused into a vascular tissue construct 5 mm in diameter using magnetic force assembly. PMID:24183699

  12. Complex dynamics of cellular automata rule 119

    NASA Astrophysics Data System (ADS)

    Chen, Fang-Fang; Chen, Fang-Yue

    2009-03-01

    In this paper, the dynamical behaviors of cellular automata rule 119 are studied from the viewpoint of symbolic dynamics in the bi-infinite symbolic sequence space Σ2. It is shown that there exists one Bernoulli-measure global attractor of rule 119, which is also the nonwandering set of the rule. Moreover, it is demonstrated that rule 119 is topologically mixing on the global attractor and possesses the positive topological entropy. Therefore, rule 119 is chaotic in the sense of both Li-Yorke and Devaney on the global attractor. It is interesting that rule 119, a member of Wolfram’s class II which was said to be simple as periodic before, actually possesses a chaotic global attractor in Σ2. Finally, it is noted that the method presented in this work is also applicable to studying the dynamics of other rules, especially the 112 Bernoulli-shift rules therein.

  13. Particles and Patterns in Cellular Automata

    SciTech Connect

    Jen, E.; Das, R.; Beasley, C.E.

    1999-06-03

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). Our objective has been to develop tools for studying particle interactions in a class of dynamical systems characterized by discreteness, determinism, local interaction, and an inherently parallel form of evolution. These systems can be described by cellular automata (CA) and the behavior we studied has improved our understanding of the nature of patterns generated by CAs, their ability to perform global computations, and their relationship to continuous dynamical systems. We have also developed a rule-table mathematics that enables one to custom-design CA rule tables to generate patterns of specified types, or to perform specified computational tasks.

  14. Threshold effects and cellular recognition. Progress report

    SciTech Connect

    Rando, R R

    1980-01-01

    In the first year we focused on developing the techniques required for the successful incorporation of synthetic glycolipids into cells. To these ends a new water-soluble spacer group (8-amino-3-6-dioxaoctanoic acid) was developed and incorporated into the cholesterol based synthetic glycolipids. These glycolipids could be incorporated into liposomes, rendering them susceptible to aggregation by the appropriate lectin. They also allowed us to define the minimal distance between the sugar moiety and membrane required for agglutination. Finally and most importantly, we were able to functionally incorporate these new glycolipids in cells and render them agglutinable with the appropriate lectins. Functional incorporation does not occur with glycolipids bearing hydropholic spacer groups. We are now in a position to begin using the new glycolipids to answer questions about the roles of cell surface sugars in cellular recognition, which is the subject of this renewal proposal.

  15. Cellular Instabilities and Self-Acceleration of Expanding Spherical Flames

    NASA Technical Reports Server (NTRS)

    Law, C. K.; Kwon, O. C.

    2003-01-01

    In the present investigation we aim to provide experimental information on and thereby understanding of the generation and propagation of spark-ignited, outwardly propagating cellular flames, with three major focuses. The first is to unambiguously demonstrate the influence of the four most important parameters in inducing hydrodynamic and diffusional-thermal cellularities, namely thermal expansion, flame thickness, non-unity Lewis number, and global activation energy. The second is to investigate the critical state for the onset of cellularity for the stretch-affected, expanding flame. The third is to identify and consequently quantify the phenomena of self-acceleration and possibly auto-turbulization of cellular flames. Due to space limitation the effects of activation energy and the critical state for the onset of cellularity will not be discussed herein. Experiments were conducted using C3H8-air and H2-O2-N2 mixtures for their opposite influences of non-equidiffusivity. The additional system parameters varied were the chamber pressure (p) and the mixture composition including the equivalence ratio (phi). From a sequence of the flame images we can assess the propensity of cell formation, and determine the instantaneous flame radius (R), the flame propagation rate, the global stretch rate experienced by the flame, the critical flame radius at which cells start to grow, and the average cell size.

  16. Effect of anisotropy on deep cellular crystal growth in directional solidification

    NASA Astrophysics Data System (ADS)

    Jiang, Han; Chen, Ming-Wen; Shi, Guo-Dong; Wang, Tao; Wang, Zi-Dong

    2016-06-01

    The effect of anisotropic surface tension and anisotropic interface kinetics on deep cellular crystal growth is studied. An asymptotic solution of deep cellular crystal growth in directional solidification is obtained by using the matched asymptotic expansion method and the multiple variable expansion method. The results show that as the anisotropic parameters increase, the total length of deep cellular crystal increases and the root depth increases, whereas the curvature of the interface near the root increases or the curvature radius decreases.

  17. Supergranular Parameters

    NASA Astrophysics Data System (ADS)

    Udayashankar, Paniveni

    2016-07-01

    I study the complexity of supergranular cells using intensity patterns from Kodaikanal solar observatory. The chaotic and turbulent aspect of the solar supergranulation can be studied by examining the interrelationships amongst the parameters characterizing supergranular cells namely size, horizontal flow field, lifetime and physical dimensions of the cells and the fractal dimension deduced from the size data. The findings are supportive of Kolmogorov's theory of turbulence. The Data consists of visually identified supergranular cells, from which a fractal dimension 'D' for supergranulation is obtained according to the relation P α AD/2 where 'A' is the area and 'P' is the perimeter of the supergranular cells. I find a fractal dimension close to about 1.3 which is consistent with that for isobars and suggests a possible turbulent origin. The cell circularity shows a dependence on the perimeter with a peak around (1.1-1.2) x 105 m. The findings are supportive of Kolmogorov's theory of turbulence.

  18. Wrinkling in Cellular Structured Composites

    NASA Astrophysics Data System (ADS)

    Kaynia, Narges; Li, Yaning; Boyce, Mary C.

    2013-03-01

    Many structured composites found in nature possess undulating and wrinkled interfacial layers that regulate mechanical, chemical, acoustic, adhesive, thermal, electrical and optical functions of the material. This research focused on the formation of wrinkling patterns in cellular structured composites and the effect of the wrinkling pattern on the overall structural response. The cellular composites consisted of stiffer interfacial layers constructing a network submerged in a soft matrix. Analytical and finite element models were developed to capture various aspects of the wrinkling mechanism. The characteristics of the undulation patterns and the instability modes were investigated as functions of model geometry and material composition. Mechanical experiments were designed to further explore the modeling results. The cellular composite samples were fabricated by using different types of elastomers and by varying the geometry and the material properties. The experimental and numerical results were consistent with the analytical predictions. The results in this research improve understanding of the mechanisms governing the undulation pattern formation in cellular composites and can be used to enable on-demand tunability of different functions to provide, among others, active control of wave propagation, mechanical stiffness and deformation, and material swelling and growth.

  19. Cellular Automata and the Humanities.

    ERIC Educational Resources Information Center

    Gallo, Ernest

    1994-01-01

    The use of cellular automata to analyze several pre-Socratic hypotheses about the evolution of the physical world is discussed. These hypotheses combine characteristics of both rigorous and metaphoric language. Since the computer demands explicit instructions for each step in the evolution of the automaton, such models can reveal conceptual…

  20. The 3-dimensional cellular automata for HIV infection

    NASA Astrophysics Data System (ADS)

    Mo, Youbin; Ren, Bin; Yang, Wencao; Shuai, Jianwei

    2014-04-01

    The HIV infection dynamics is discussed in detail with a 3-dimensional cellular automata model in this paper. The model can reproduce the three-phase development, i.e., the acute period, the asymptotic period and the AIDS period, observed in the HIV-infected patients in a clinic. We show that the 3D HIV model performs a better robustness on the model parameters than the 2D cellular automata. Furthermore, we reveal that the occurrence of a perpetual source to successively generate infectious waves to spread to the whole system drives the model from the asymptotic state to the AIDS state.

  1. Cellular instability in rapid directional solidification - Bifurcation theory

    NASA Technical Reports Server (NTRS)

    Braun, R. J.; Davis, S. H.

    1992-01-01

    Merchant and Davis performed a linear stability analysis on a model for the directional solidification of a dilute binary alloy valid for all speeds. The analysis revealed that nonequilibrium segregation effects modify the Mullins and Sekerka cellular mode, whereas attachment kinetics has no effect on these cells. In this paper, the nonlinear stability of the steady cellular mode is analyzed. A Landau equation is obtained that determines the amplitude of the cells. The Landau coefficient here depends on both nonequilibrium segregation effects and attachment kinetics. This equation gives the ranges of parameters for subcritical bifurcation (jump transition) or supercritical bifurcation (smooth transition) to cells.

  2. Light Weight Biomorphous Cellular Ceramics from Cellulose Templates

    NASA Technical Reports Server (NTRS)

    Singh, Mrityunjay; Yee, Bo-Moon; Gray, Hugh R. (Technical Monitor)

    2003-01-01

    Bimorphous ceramics are a new class of materials that can be fabricated from the cellulose templates derived from natural biopolymers. These biopolymers are abundantly available in nature and are produced by the photosynthesis process. The wood cellulose derived carbon templates have three- dimensional interconnectivity. A wide variety of non-oxide and oxide based ceramics have been fabricated by template conversion using infiltration and reaction-based processes. The cellular anatomy of the cellulose templates plays a key role in determining the processing parameters (pyrolysis, infiltration conditions, etc.) and resulting ceramic materials. The processing approach, microstructure, and mechanical properties of the biomorphous cellular ceramics (silicon carbide and oxide based) have been discussed.

  3. Nonsynchronous updating in the multiverse of cellular automata.

    PubMed

    Reia, Sandro M; Kinouchi, Osame

    2015-04-01

    In this paper we study updating effects on cellular automata rule space. We consider a subset of 6144 order-3 automata from the space of 262144 bidimensional outer-totalistic rules. We compare synchronous to asynchronous and sequential updatings. Focusing on two automata, we discuss how update changes destroy typical structures of these rules. Besides, we show that the first-order phase transition in the multiverse of synchronous cellular automata, revealed with the use of a recently introduced control parameter, seems to be robust not only to changes in update schema but also to different initial densities. PMID:25974442

  4. Nonsynchronous updating in the multiverse of cellular automata

    NASA Astrophysics Data System (ADS)

    Reia, Sandro M.; Kinouchi, Osame

    2015-04-01

    In this paper we study updating effects on cellular automata rule space. We consider a subset of 6144 order-3 automata from the space of 262144 bidimensional outer-totalistic rules. We compare synchronous to asynchronous and sequential updatings. Focusing on two automata, we discuss how update changes destroy typical structures of these rules. Besides, we show that the first-order phase transition in the multiverse of synchronous cellular automata, revealed with the use of a recently introduced control parameter, seems to be robust not only to changes in update schema but also to different initial densities.

  5. Torsins Are Essential Regulators of Cellular Lipid Metabolism.

    PubMed

    Grillet, Micheline; Dominguez Gonzalez, Beatriz; Sicart, Adria; Pöttler, Maria; Cascalho, Ana; Billion, Karolien; Hernandez Diaz, Sergio; Swerts, Jef; Naismith, Teresa V; Gounko, Natalia V; Verstreken, Patrik; Hanson, Phyllis I; Goodchild, Rose E

    2016-08-01

    Torsins are developmentally essential AAA+ proteins, and mutation of human torsinA causes the neurological disease DYT1 dystonia. They localize in the ER membranes, but their cellular function remains unclear. We now show that dTorsin is required in Drosophila adipose tissue, where it suppresses triglyceride levels, promotes cell growth, and elevates membrane lipid content. We also see that human torsinA at the inner nuclear membrane is associated with membrane expansion and elevated cellular lipid content. Furthermore, the key lipid metabolizing enzyme, lipin, is mislocalized in dTorsin-KO cells, and dTorsin increases levels of the lipin substrate, phosphatidate, and reduces the product, diacylglycerol. Finally, genetic suppression of dLipin rescues dTorsin-KO defects, including adipose cell size, animal growth, and survival. These findings identify that torsins are essential regulators of cellular lipid metabolism and implicate disturbed lipid biology in childhood-onset DYT1 dystonia. PMID:27453503

  6. Cellular therapy in bone-tendon interface regeneration

    PubMed Central

    Rothrauff, Benjamin B; Tuan, Rocky S

    2014-01-01

    The intrasynovial bone-tendon interface is a gradual transition from soft tissue to bone, with two intervening zones of uncalcified and calcified fibrocartilage. Following injury, the native anatomy is not restored, resulting in inferior mechanical properties and an increased risk of re-injury. Recent in vivo studies provide evidence of improved healing when surgical repair of the bone-tendon interface is augmented with cells capable of undergoing chondrogenesis. In particular, cellular therapy in bone-tendon healing can promote fibrocartilage formation and associated improvements in mechanical properties. Despite these promising results in animal models, cellular therapy in human patients remains largely unexplored. This review highlights the development and structure-function relationship of normal bone-tendon insertions. The natural healing response to injury is discussed, with subsequent review of recent research on cellular approaches for improved healing. Finally, opportunities for translating in vivo findings into clinical practice are identified. PMID:24326955

  7. 3D surface reconstruction and visualization of the Drosophila wing imaginal disc at cellular resolution

    NASA Astrophysics Data System (ADS)

    Bai, Linge; Widmann, Thomas; Jülicher, Frank; Dahmann, Christian; Breen, David

    2013-01-01

    Quantifying and visualizing the shape of developing biological tissues provide information about the morphogenetic processes in multicellular organisms. The size and shape of biological tissues depend on the number, size, shape, and arrangement of the constituting cells. To better understand the mechanisms that guide tissues into their final shape, it is important to investigate the cellular arrangement within tissues. Here we present a data processing pipeline to generate 3D volumetric surface models of epithelial tissues, as well as geometric descriptions of the tissues' apical cell cross-sections. The data processing pipeline includes image acquisition, editing, processing and analysis, 2D cell mesh generation, 3D contourbased surface reconstruction, cell mesh projection, followed by geometric calculations and color-based visualization of morphological parameters. In their first utilization we have applied these procedures to construct a 3D volumetric surface model at cellular resolution of the wing imaginal disc of Drosophila melanogaster. The ultimate goal of the reported effort is to produce tools for the creation of detailed 3D geometric models of the individual cells in epithelial tissues. To date, 3D volumetric surface models of the whole wing imaginal disc have been created, and the apicolateral cell boundaries have been identified, allowing for the calculation and visualization of cell parameters, e.g. apical cross-sectional area of cells. The calculation and visualization of morphological parameters show position-dependent patterns of cell shape in the wing imaginal disc. Our procedures should offer a general data processing pipeline for the construction of 3D volumetric surface models of a wide variety of epithelial tissues.

  8. Cellular immunity and lymphokine production during spaceflights

    NASA Technical Reports Server (NTRS)

    Konstantinova, I. V.; Sonnenfeld, G.; Lesniak, A. T.; Shaffar, L.; Mandel, A.; Rykova, M. P.; Antropova, E. N.; Ferrua, B.

    1991-01-01

    Results are presented on changes in cellular immunity and in the production of lymphokine in spacecrews during spaceflights. Measurements were carried out on blood samples collected from 50 cosmonauts before and after spaceflights of different duration, on board Salyut-6, Salyut-7, or Mir. Additional data were obtained from rats flown on board the Cosmos-1667 and Cosmos-1887 biosatellites. The parameters measured included the PHA responsiveness of T lymphocytes, the activity of T-helper cells and of nonspecific T suppressors, the activity of the so-called natural killer lymphocytes, the production of gamma-interferon, and the cell-surface markers. Results showed that the frequency and the extent of changes in the immunologic resistance of subjects depended on the duration of the flight. However, even after the most prolonged (365 days) spaceflight, the changes observed were mostly of a functional character with subsequent rapid return to normal.

  9. Improved Cellular Infiltration in Electrospun Fiber via Engineered Porosity

    PubMed Central

    NAM, JIN; HUANG, YAN; AGARWAL, SUDHA; LANNUTTI, JOHN

    2016-01-01

    Small pore sizes inherent to electrospun matrices can hinder efficient cellular ingrowth. To facilitate infiltration while retaining its extracellular matrix-like character, electrospinning was combined with salt leaching to produce a scaffold having deliberate, engineered delaminations. We made elegant use of a specific randomizing component of the electrospinning process, the Taylor Cone and the falling fiber beneath it, to produce a uniform, well-spread distribution of salt particles. After 3 weeks of culture, up to 4 mm of cellular infiltration was observed, along with cellular coverage of up to 70% within the delaminations. To our knowledge, this represents the first observation of extensive cellular infiltration of electrospun matrices. Infiltration appears to be driven primarily by localized proliferation rather than coordinated cellular locomotion. Cells also moved from the salt-generated porosity into the surrounding electrospun fiber matrix. Given that the details of salt deposition (amount, size, and number density) are far from optimized, the result provides a convincing illustration of the ability of mammalian cells to interact with appropriately tailored electrospun matrices. These layered structures can be precisely fabricated by varying the deposition interval and particle size conceivably to produce in vivo-like gradients in porosity such that the resulting scaffolds better resemble the desired final structure. PMID:17536926

  10. Thermodynamics of cellular statistical inference

    NASA Astrophysics Data System (ADS)

    Lang, Alex; Fisher, Charles; Mehta, Pankaj

    2014-03-01

    Successful organisms must be capable of accurately sensing the surrounding environment in order to locate nutrients and evade toxins or predators. However, single cell organisms face a multitude of limitations on their accuracy of sensing. Berg and Purcell first examined the canonical example of statistical limitations to cellular learning of a diffusing chemical and established a fundamental limit to statistical accuracy. Recent work has shown that the Berg and Purcell learning limit can be exceeded using Maximum Likelihood Estimation. Here, we recast the cellular sensing problem as a statistical inference problem and discuss the relationship between the efficiency of an estimator and its thermodynamic properties. We explicitly model a single non-equilibrium receptor and examine the constraints on statistical inference imposed by noisy biochemical networks. Our work shows that cells must balance sample number, specificity, and energy consumption when performing statistical inference. These tradeoffs place significant constraints on the practical implementation of statistical estimators in a cell.

  11. Peroxisome Metabolism and Cellular Aging

    PubMed Central

    Titorenko, Vladimir I.; Terlecky, Stanley R.

    2010-01-01

    The essential role of peroxisomes in fatty acid oxidation, anaplerotic metabolism, and hydrogen peroxide turnover is well established. Recent findings suggest these and other related biochemical processes governed by the organelle may also play a critical role in regulating cellular aging. The goal of this review is to summarize and integrate into a model, the evidence that peroxisome metabolism actually helps define the replicative and chronological age of a eukaryotic cell. In this model, peroxisomal reactive oxygen species (ROS) are seen as altering organelle biogenesis and function, and eliciting changes in the dynamic communication networks that exist between peroxisomes and other cellular compartments. At low levels, peroxisomal ROS activate an anti-aging program in the cell; at concentrations beyond a specific threshold, a pro-aging course is triggered. PMID:21083858

  12. Cellular solidification of transparent monotectics

    NASA Technical Reports Server (NTRS)

    Kaulker, W. F.

    1986-01-01

    Understanding how liquid phase particles are engulfed or pushed during freezing of a monotectic is addressed. The additional complication is that the solid-liquid interface is nonplanar due to constitutional undercooling. Some evidence of particle pushing where the particles are the liquid phase of the montectic was already observed. Cellular freezing of the succinonitrile-glycerol system also occurred. Only a few compositions were tested at that time. The starting materials were not especially pure so that cellular interface observed was likely due to the presence of unkown impurities, the major portion of which was water. Topics addressed include: the effort of modeling the particle pushing process using the computer, establishing an apparatus for the determination of phase diagrams, and the measurement of the temperature gradients with a specimen which will solidify on the temperature gradient microscope stage.

  13. Hox Targets and Cellular Functions

    PubMed Central

    Sánchez-Herrero, Ernesto

    2013-01-01

    Hox genes are a group of genes that specify structures along the anteroposterior axis in bilaterians. Although in many cases they do so by modifying a homologous structure with a different (or no) Hox input, there are also examples of Hox genes constructing new organs with no homology in other regions of the body. Hox genes determine structures though the regulation of targets implementing cellular functions and by coordinating cell behavior. The genetic organization to construct or modify a certain organ involves both a genetic cascade through intermediate transcription factors and a direct regulation of targets carrying out cellular functions. In this review I discuss new data from genome-wide techniques, as well as previous genetic and developmental information, to describe some examples of Hox regulation of different cell functions. I also discuss the organization of genetic cascades leading to the development of new organs, mainly using Drosophila melanogaster as the model to analyze Hox function. PMID:24490109

  14. Optofluidic Detection for Cellular Phenotyping

    PubMed Central

    Tung, Yi-Chung; Huang, Nien-Tsu; Oh, Bo-Ram; Patra, Bishnubrata; Pan, Chi-Chun; Qiu, Teng; Paul, K. Chu; Zhang, Wenjun; Kurabayashi, Katsuo

    2012-01-01

    Quantitative analysis of the output of processes and molecular interactions within a single cell is highly critical to the advancement of accurate disease screening and personalized medicine. Optical detection is one of the most broadly adapted measurement methods in biological and clinical assays and serves cellular phenotyping. Recently, microfluidics has obtained increasing attention due to several advantages, such as small sample and reagent volumes, very high throughput, and accurate flow control in the spatial and temporal domains. Optofluidics, which is the attempt to integrate optics with microfluidic, shows great promise to enable on-chip phenotypic measurements with high precision, sensitivity, specificity, and simplicity. This paper reviews the most recent developments of optofluidic technologies for cellular phenotyping optical detection. PMID:22854915

  15. Chiral hexagonal cellular sandwich structure: a vibro-acoustic assessment

    NASA Astrophysics Data System (ADS)

    Lew, Tze L.; Spadoni, Alessandro; Scarpa, Fabrizio; Ruzzene, Massimo

    2005-05-01

    In this work we describe the vibroacoustic behavior of a novel concept of core for sandwich structures featuring auxetic characteristics, enhanced shear stiffness and compressive strength compared to classical cellular cores in sandwich components for sandwich applications. The out-plane properties and density values are described in terms of geometric parameters of the honeycomb unit cells. Opposite to classical honeycomb cellular applications, the hexagonal chiral structure presents a noncentresymemetric configuration, i.e., a "mirror" symmetrical topology. The derived mechanical properties are used to assess the modal behaviour and modal densities of sandwich plate elements with chiral and standard cellular cores. The analytical findings are backed up by structural tests on chiral honeycomb plates and sandwich beams.

  16. Analysis of the influence of inert particles on the propagation of a cellular heterogeneous detonation

    NASA Astrophysics Data System (ADS)

    Fedorov, A. V.; Kratova, Y. V.

    2015-05-01

    The interaction of a cellular detonation wave with a cloud of inert particles is investigated numerically. The regimes of propagation of the heterogeneous cellular detonation and its suppression are identified. The influence of various parameters of the inert cloud is demonstrated. The critical length of the cloud for detonation suppression is determined. It is shown that the disperse composition and the non-uniform distribution of particles of the particle cloud are important parameters affecting the detonation propagation mode.

  17. Xtoys: Cellular automata on xwindows

    SciTech Connect

    Creutz, M.

    1995-08-15

    Xtoys is a collection of xwindow programs for demonstrating simulations of various statistical models. Included are xising, for the two dimensional Ising model, xpotts, for the q-state Potts model, xautomalab, for a fairly general class of totalistic cellular automata, xsand, for the Bak-Tang-Wiesenfield model of self organized criticality, and xfires, a simple forest fire simulation. The programs should compile on any machine supporting xwindows.

  18. Effect of canopy structure and open-top chamber techniques on micrometeorological parameters and the gradients and transport of water vapor, carbon dioxide and ozone in the canopies of plum trees (`prunus salicina`) in the San Joaquin valley. Final report

    SciTech Connect

    Grantz, D.A.; Vaughn, D.L.; Metheny, P.A.; Malkus, P.; Wosnik, K.

    1995-03-15

    Plum trees (Prunus salicina cv. Casselman) were exposed to ozone in open-top chambers (OTC) or chamberless plots, and trace gas concentrations and microenvironmental conditions were monitored within tree canopies inside the outside the OTC. Concentrations of ozone, carbon dioxide and water vapor, leaf and air temperature, light intensity, and wind speed were measured at nine positions in the tree canopies. The objectives were to: (1) map the distribution of microenvironmental parameters within the canopies inside and outside the OTC; (2) determine transport parameters for gas exchange, and (3) calculate ozone flux. Significant vertical and horizontal gradients were observed; gradients were diminished and often inverted inside relative to outside the OTC due to air distribution at the bottom of the OCT. Ozone flux was readily modeled from measures of stomatal conductance, nonstomatal conductance and ozone concentration at the leaf surface.

  19. Competitive potential of cellular mobile telecommunications

    SciTech Connect

    Ware, H.

    1983-02-03

    The Federal Communications Commission (FCC) has recently issued rules for the commercial operation of a telecommunications technology not previously in commercial use: the cellular mobile radio. The author has carefully considered the potential for competition between cellular systems and for competition between cellular radio and alternative communications technologies under the regulatory scheme which has been adopted by the FCC. He finds that competition between cellular and wire-line services can be viable if cellular cost and demand data are carefully tracked to avoid market congestion and if cellular or other techniques are not allowed to undercut selected local exchange rates.

  20. Final Report

    SciTech Connect

    Gurney, Kevin R

    2015-01-12

    This document constitutes the final report under DOE grant DE-FG-08ER64649. The organization of this document is as follows: first, I will review the original scope of the proposed research. Second, I will present the current draft of a paper nearing submission to Nature Climate Change on the initial results of this funded effort. Finally, I will present the last phase of the research under this grant which has supported a Ph.D. student. To that end, I will present the graduate student’s proposed research, a portion of which is completed and reflected in the paper nearing submission. This final work phase will be completed in the next 12 months. This final workphase will likely result in 1-2 additional publications and we consider the results (as exemplified by the current paper) high quality. The continuing results will acknowledge the funding provided by DOE grant DE-FG-08ER64649.

  1. Final Report

    SciTech Connect

    DeTar, Carleton

    2012-12-10

    This document constitutes the Final Report for award DE-FC02-06ER41446 as required by the Office of Science. It summarizes accomplishments and provides copies of scientific publications with significant contribution from this award.

  2. A magnetically actuated cellular strain assessment tool for quantitative analysis of strain induced cellular reorientation and actin alignment.

    PubMed

    Khademolhosseini, F; Liu, C-C; Lim, C J; Chiao, M

    2016-08-01

    Commercially available cell strain tools, such as pneumatically actuated elastomer substrates, require special culture plates, pumps, and incubator setups. In this work, we present a magnetically actuated cellular strain assessment tool (MACSAT) that can be implemented using off-the-shelf components and conventional incubators. We determine the strain field on the MACSAT elastomer substrate using numerical models and experimental measurements and show that a specific region of the elastomer substrate undergoes a quasi-uniaxial 2D stretch, and that cells confined to this region of the MACSAT elastomer substrate undergo tensile, compressive, or zero axial strain depending on their angle of orientation. Using the MACSAT to apply cyclic strain on endothelial cells, we demonstrate that actin filaments within the cells reorient away from the stretching direction, towards the directions of minimum axial strain. We show that the final actin orientation angles in strained cells are spread over a region of compressive axial strain, confirming previous findings on the existence of a varied pre-tension in the actin filaments of the cytoskeleton. We also demonstrate that strained cells exhibit distinctly different values of actin alignment coherency compared to unstrained cells and therefore propose that this parameter, i.e., the coherency of actin alignment, can be used as a new readout to determine the occurrence/extent of actin alignment in cell strain experiments. The tools and methods demonstrated in this study are simple and accessible and can be easily replicated by other researchers to study the strain response of other adherent cells. PMID:27587150

  3. Passive cellular microrheology in developing fruit fly embryos

    NASA Astrophysics Data System (ADS)

    Crews, Sarah; Ma, Xiaoyan; Lawrence, Stacey; Hutson, M. Shane

    2012-02-01

    The development of fruit fly (Drosophila) embryos involves spatial and temporal regulation of cellular mechanical properties. These properties can be probed in vivo using laser hole drilling experiments; however, this technique only infers relative forces. Conversion to absolute forces requires measurement of cellular viscoelastic properties. Here, we use passive microrheology of fluorescently labeled cell membranes to measure the viscoelastic properties of amnioserosa cells. These dynamic epithelial cells play an important mechanical role during two developmental stages: germ band retraction and dorsal closure. Passive microrheology in this system is confounded by active contractions in the cytoskeleton. Thus, the fruit fly embryos are transiently anesthetized with CO2, halting active cellular movements, leaving only passive Brownian motion. The power spectra of these fluctuations are well fit by a Lorentzian -- as expected for Brownian motion -- and allow us to extract cellular viscoelastic parameters at different developmental stages. These measured parameters inform previous hole-drilling experiments and provide inputs for quantitative computational models of fruit fly embryonic development.

  4. Statistical physical models of cellular motility

    NASA Astrophysics Data System (ADS)

    Banigan, Edward J.

    Cellular motility is required for a wide range of biological behaviors and functions, and the topic poses a number of interesting physical questions. In this work, we construct and analyze models of various aspects of cellular motility using tools and ideas from statistical physics. We begin with a Brownian dynamics model for actin-polymerization-driven motility, which is responsible for cell crawling and "rocketing" motility of pathogens. Within this model, we explore the robustness of self-diffusiophoresis, which is a general mechanism of motility. Using this mechanism, an object such as a cell catalyzes a reaction that generates a steady-state concentration gradient that propels the object in a particular direction. We then apply these ideas to a model for depolymerization-driven motility during bacterial chromosome segregation. We find that depolymerization and protein-protein binding interactions alone are sufficient to robustly pull a chromosome, even against large loads. Next, we investigate how forces and kinetics interact during eukaryotic mitosis with a many-microtubule model. Microtubules exert forces on chromosomes, but since individual microtubules grow and shrink in a force-dependent way, these forces lead to bistable collective microtubule dynamics, which provides a mechanism for chromosome oscillations and microtubule-based tension sensing. Finally, we explore kinematic aspects of cell motility in the context of the immune system. We develop quantitative methods for analyzing cell migration statistics collected during imaging experiments. We find that during chronic infection in the brain, T cells run and pause stochastically, following the statistics of a generalized Levy walk. These statistics may contribute to immune function by mimicking an evolutionarily conserved efficient search strategy. Additionally, we find that naive T cells migrating in lymph nodes also obey non-Gaussian statistics. Altogether, our work demonstrates how physical

  5. Fluorescent sensing of fluoride in cellular system.

    PubMed

    Jiao, Yang; Zhu, Baocun; Chen, Jihua; Duan, Xiaohong

    2015-01-01

    Fluoride ions have the important roles in a lot of physiological activities related with biological and medical system, such as water fluoridation, caries treatment, and bone disease treatment. Great efforts have been made to develop new methods and strategies for F(-) detection in the past decades. Traditional methods for the detection of F(-) including ion chromatography, ion-selective electrodes, and spectroscopic techniques have the limitations in the biomedicine research. The fluorescent probes for F(-) are very promising that overcome some drawbacks of traditional fluoride detection methods. These probes exhibit high selectivity, high sensitivity as well as quick response to the detection of fluoride anions. The review commences with a brief description of photophysical mechanisms for fluorescent probes for fluoride, including photo induced electron transfer (PET), intramolecular charge transfer (ICT), fluorescence resonance energy transfer (FRET), and excited-state intramolecular proton transfer (ESIPT). Followed by a discussion about common dyes for fluorescent fluoride probes, such as anthracene, naphalimide, pyrene, BODIPY, fluorescein, rhodamine, resorufin, coumarin, cyanine, and near-infrared (NIR) dyes. We divide the fluorescent probes for fluoride in cellular application systems into nine groups, for example, type of hydrogen bonds, type of cleavage of Si-O bonds, type of Si-O bond cleavage and cylization reactions, etc. We also review the recent reported carriers in the delivery of fluorescent fluoride probes. Seventy-four typical fluorescent fluoride probes are listed and compared in detail, including quantum yield, reaction medium, excitation and emission wavelengths, linear detection range, selectivity for F(-), mechanism, and analytical applications. Finally, we discuss the future challenges of the application of fluorescent fluoride probes in cellular system and in vivo. We wish that more and more excellent fluorescent fluoride probes will be

  6. Fluorescent Sensing of Fluoride in Cellular System

    PubMed Central

    Jiao, Yang; Zhu, Baocun; Chen, Jihua; Duan, Xiaohong

    2015-01-01

    Fluoride ions have the important roles in a lot of physiological activities related with biological and medical system, such as water fluoridation, caries treatment, and bone disease treatment. Great efforts have been made to develop new methods and strategies for F- detection in the past decades. Traditional methods for the detection of F- including ion chromatography, ion-selective electrodes, and spectroscopic techniques have the limitations in the biomedicine research. The fluorescent probes for F- are very promising that overcome some drawbacks of traditional fluoride detection methods. These probes exhibit high selectivity, high sensitivity as well as quick response to the detection of fluoride anions. The review commences with a brief description of photophysical mechanisms for fluorescent probes for fluoride, including photo induced electron transfer (PET), intramolecular charge transfer (ICT), fluorescence resonance energy transfer (FRET), and excited-state intramolecular proton transfer (ESIPT). Followed by a discussion about common dyes for fluorescent fluoride probes, such as anthracene, naphalimide, pyrene, BODIPY, fluorescein, rhodamine, resorufin, coumarin, cyanine, and near-infrared (NIR) dyes. We divide the fluorescent probes for fluoride in cellular application systems into nine groups, for example, type of hydrogen bonds, type of cleavage of Si-O bonds, type of Si-O bond cleavage and cylization reactions, etc. We also review the recent reported carriers in the delivery of fluorescent fluoride probes. Seventy-four typical fluorescent fluoride probes are listed and compared in detail, including quantum yield, reaction medium, excitation and emission wavelengths, linear detection range, selectivity for F-, mechanism, and analytical applications. Finally, we discuss the future challenges of the application of fluorescent fluoride probes in cellular system and in vivo. We wish that more and more excellent fluorescent fluoride probes will be developed

  7. Therapeutic cloning and cellular reprogramming.

    PubMed

    Rodriguez, Ramon M; Ross, Pablo J; Cibelli, Jose B

    2012-01-01

    Embryonic stem cells are capable of differentiating into any cell-type present in an adult organism, and constitute a renewable source of tissue for regenerative therapies. The transplant of allogenic stem cells is challenging due to the risk of immune rejection. Nevertheless, somatic cell reprogramming techniques allow the generation of isogenic embryonic stem cells, genetically identical to the patient. In this chapter we will discuss the cellular reprogramming techniques in the context of regenerative therapy and the biological and technical barriers that they will need to overcome before clinical use. PMID:22457116

  8. Symmetry analysis of cellular automata

    NASA Astrophysics Data System (ADS)

    García-Morales, V.

    2013-01-01

    By means of B-calculus [V. García-Morales, Phys. Lett. A 376 (2012) 2645] a universal map for deterministic cellular automata (CAs) has been derived. The latter is shown here to be invariant upon certain transformations (global complementation, reflection and shift). When constructing CA rules in terms of rules of lower range a new symmetry, “invariance under construction” is uncovered. Modular arithmetic is also reformulated within B-calculus and a new symmetry of certain totalistic CA rules, which calculate the Pascal simplices modulo an integer number p, is then also uncovered.

  9. Cellular immune responses to HIV

    NASA Astrophysics Data System (ADS)

    McMichael, Andrew J.; Rowland-Jones, Sarah L.

    2001-04-01

    The cellular immune response to the human immunodeficiency virus, mediated by T lymphocytes, seems strong but fails to control the infection completely. In most virus infections, T cells either eliminate the virus or suppress it indefinitely as a harmless, persisting infection. But the human immunodeficiency virus undermines this control by infecting key immune cells, thereby impairing the response of both the infected CD4+ T cells and the uninfected CD8+ T cells. The failure of the latter to function efficiently facilitates the escape of virus from immune control and the collapse of the whole immune system.

  10. Quantum cellular automata without particles

    NASA Astrophysics Data System (ADS)

    Meyer, David A.; Shakeel, Asif

    2016-01-01

    Quantum cellular automata (QCA) constitute space and time homogeneous discrete models for quantum field theories (QFTs). Although QFTs are defined without reference to particles, computations are done in terms of Feynman diagrams, which are explicitly interpreted in terms of interacting particles. Similarly, the easiest QCA to construct are quantum lattice gas automata (QLGA). A natural question then is, which QCA are not QLGA? Here we construct a nontrivial example of such a QCA; it provides a simple model in 1 +1 dimensions with no particle interpretation at the scale where the QCA dynamics are homogeneous.

  11. The Cellular Basis of Aging

    PubMed Central

    Scoggin, Charles H.

    1981-01-01

    Normal cells have only a finite life span before they die. The process known as aging may occur as a result of continued damage to the cell or as a result of expression of predetermined information within the genetic structure of the cell. Both processes lead to progressive cellular dysfunction which is evidenced by the organs of the body as aging. By understanding how individual cells age we will gain insight into how the body as a whole ages. The impact of such knowledge on science and society is a matter of both conjecture and concern. PMID:7336718

  12. Primitive control of cellular metabolism

    NASA Technical Reports Server (NTRS)

    Mitz, M. A.

    1974-01-01

    It is pointed out that control substances must have existed from the earliest times in the evolution of life and that the same control mechanisms must exist today. The investigation reported is concerned with the concept that carbon dioxide is a primitive regulator of cell function. The effects of carbon dioxide on cellular materials are examined, taking into account questions of solubilization, dissociation, changes of charge, stabilization, structural changes, wettability, the exclusion of other gases, the activation of compounds, changes in plasticity, and changes in membrane permeability.

  13. Protein accounting in the cellular economy

    PubMed Central

    Vázquez-Laslop, Nora; Mankin, Alexander S.

    2014-01-01

    Knowing the copy number of cellular proteins is critical for understanding cell physiology. By being able to measure the absolute synthesis rates of the majority of cellular proteins, Li et al. (2014) gain insights into key aspects of translation regulation and fundamental principles of cellular strategies to adjust protein synthesis according to the needs. PMID:24766801

  14. Protein accounting in the cellular economy.

    PubMed

    Vázquez-Laslop, Nora; Mankin, Alexander S

    2014-04-24

    Knowing the copy number of cellular proteins is critical for understanding cell physiology. By being able to measure the absolute synthesis rates of the majority of cellular proteins, Li et al. gain insights into key aspects of translation regulation and fundamental principles of cellular strategies to adjust protein synthesis according to the functional needs. PMID:24766801

  15. Ion beam analysis based on cellular nonlinear networks

    NASA Astrophysics Data System (ADS)

    Senger, V.; Tetzlaff, R.; Reichau, H.; Ratzinger, U.

    2011-07-01

    The development of a non- destructive measurement method for ion beam parameters has been treated in various projects. Although results are promising, the high complexity of beam dynamics has made it impossible to implement a real time process control up to now. In this paper we will propose analysing methods based on the dynamics of Cellular Nonlinear Networks (CNN) that can be implemented on pixel parallel CNN based architectures and yield satisfying results even at low resolutions.

  16. Geolocation Technologies Final Report

    SciTech Connect

    Magnoli, D E

    2003-06-02

    This paper is the final report for LL998 In Situ Sensing Subtask 7 (Geo-location) undertaken for NNSA NA-22 enabling technologies R&D for Counterproliferation Detection. A few state-of-the-art resolution parameters are presented for accelerometers, indoor and outdoor GPS (Global Positioning Satellite) systems, and INSs (Inertial Navigation Systems). New technologies are described, including one which has demonstrated the ability to track within a building to a resolution of under a foot.

  17. The similia principle: results obtained in a cellular model system.

    PubMed

    Wiegant, Fred; Van Wijk, Roeland

    2010-01-01

    This paper describes the results of a research program focused on the beneficial effect of low dose stress conditions that were applied according to the similia principle to cells previously disturbed by more severe stress conditions. In first instance, we discuss criteria for research on the similia principle at the cellular level. Then, the homologous ('isopathic') approach is reviewed, in which the initial (high dose) stress used to disturb cellular physiology and the subsequent (low dose) stress are identical. Beneficial effects of low dose stress are described in terms of increased cellular survival capacity and at the molecular level as an increase in the synthesis of heat shock proteins (hsps). Both phenomena reflect a stimulation of the endogenous cellular self-recovery capacity. Low dose stress conditions applied in a homologous approach stimulate the synthesis of hsps and enhance survival in comparison with stressed cells that were incubated in the absence of low dose stress conditions. Thirdly, the specificity of the low dose stress condition is described where the initial (high dose) stress is different in nature from the subsequently applied (low dose) stress; the heterologous or 'heteropathic' approach. The results support the similia principle at the cellular level and add to understanding of how low dose stress conditions influence the regulatory processes underlying self-recovery. In addition, the phenomenon of 'symptom aggravation' which is also observed at the cellular level, is discussed in the context of self-recovery. Finally, the difference in efficiency between the homologous and the heterologous approach is discussed; a perspective is indicated for further research; and the relationship between studies on the similia principle and the recently introduced concept of 'postconditioning hormesis' is emphasized. PMID:20129172

  18. Soil thermal resistivity and thermal stability measuring instrument. Volume 2. Manual for operation and use of the thermal property analyzer and statistical weather analysis program to determine thermal design parameters. Final report

    SciTech Connect

    Boggs, S.A.; Radhakrishna, H.S.

    1981-11-01

    Numerous considerations influence the thermal design of an underground power cable, including the soil thermal resistivity, thermal diffusivity and thermal stability. Each of these properties is a function of soil moisture which is, in turn, a function of past weather, soil composition, and biological burden. The Neher-McGrath formalism has been widely used for thermal cable design. However, this formalism assumes knowledge of soil thermal properties (resistivity and diffusivity). For design purposes, these parameters should be treated statistically, since weather varies greatly from year-to-year. As well, soil thermal property surveys are normally required along the route to assess the thermal quality of the native soil. This project is intended to fill the gap between the need to carry out thermal design and the use of the Neher-McGrath formalism which is normally employed. This goal has been addressed through: development of instrumentation and methods of measuring soil thermal properties in situ and in the laboratory; recommendation of methods for conducting soil surveys along a proposed cable route and of assessing the thermal quality of soils; and development of a computerized method to treat soil thermal design parameters on a statistical basis using computerized weather records as supplied by the US Environmental Data Service. The use of the methods and instrumentation developed as a result of this contract should permit less conservative thermal design thereby improving the economics of underground transmission. As well, these techniques and instrumentation facilitate weather-dependent prediction of cable ampacity for installed cables, monitoring of backfill thermal stability, and many other new practices.

  19. Cellular Biology of Prion Diseases

    PubMed Central

    Harris, David A.

    1999-01-01

    Prion diseases are fatal neurodegenerative disorders of humans and animals that are important because of their impact on public health and because they exemplify a novel mechanism of infectivity and biological information transfer. These diseases are caused by conformational conversion of a normal host glycoprotein (PrPC) into an infectious isoform (PrPSc) that is devoid of nucleic acid. This review focuses on the current understanding of prion diseases at the cell biological level. The characteristics of the diseases are introduced, and a brief history and description of the prion hypothesis are given. Information is then presented about the structure, expression, biosynthesis, and possible function of PrPC, as well as its posttranslational processing, cellular localization, and trafficking. The latest findings concerning PrPSc are then discussed, including cell culture systems used to generate this pathogenic isoform, the subcellular distribution of the protein, its membrane attachment, proteolytic processing, and its kinetics and sites of synthesis. Information is also provided on molecular models of the PrPC→PrPSc conversion reaction and the possible role of cellular chaperones. The review concludes with suggestions of several important avenues for future investigation. PMID:10398674

  20. Cellular senescence and protein degradation

    PubMed Central

    Deschênes-Simard, Xavier; Lessard, Frédéric; Gaumont-Leclerc, Marie-France; Bardeesy, Nabeel; Ferbeyre, Gerardo

    2014-01-01

    Autophagy and the ubiquitin–proteasome pathway (UPP) are the major protein degradation systems in eukaryotic cells. Whereas the former mediate a bulk nonspecific degradation, the UPP allows a rapid degradation of specific proteins. Both systems have been shown to play a role in tumorigenesis, and the interest in developing therapeutic agents inhibiting protein degradation is steadily growing. However, emerging data point to a critical role for autophagy in cellular senescence, an established tumor suppressor mechanism. Recently, a selective protein degradation process mediated by the UPP was also shown to contribute to the senescence phenotype. This process is tightly regulated by E3 ubiquitin ligases, deubiquitinases, and several post-translational modifications of target proteins. Illustrating the complexity of UPP, more than 600 human genes have been shown to encode E3 ubiquitin ligases, a number which exceeds that of the protein kinases. Nevertheless, our knowledge of proteasome-dependent protein degradation as a regulated process in cellular contexts such as cancer and senescence remains very limited. Here we discuss the implications of protein degradation in senescence and attempt to relate this function to the protein degradation pattern observed in cancer cells. PMID:24866342

  1. Micromechanics of cellularized biopolymer networks

    PubMed Central

    Jones, Christopher A. R.; Cibula, Matthew; Feng, Jingchen; Krnacik, Emma A.; McIntyre, David H.; Levine, Herbert; Sun, Bo

    2015-01-01

    Collagen gels are widely used in experiments on cell mechanics because they mimic the extracellular matrix in physiological conditions. Collagen gels are often characterized by their bulk rheology; however, variations in the collagen fiber microstructure and cell adhesion forces cause the mechanical properties to be inhomogeneous at the cellular scale. We study the mechanics of type I collagen on the scale of tens to hundreds of microns by using holographic optical tweezers to apply pN forces to microparticles embedded in the collagen fiber network. We find that in response to optical forces, particle displacements are inhomogeneous, anisotropic, and asymmetric. Gels prepared at 21 °C and 37 °C show qualitative difference in their micromechanical characteristics. We also demonstrate that contracting cells remodel the micromechanics of their surrounding extracellular matrix in a strain- and distance-dependent manner. To further understand the micromechanics of cellularized extracellular matrix, we have constructed a computational model which reproduces the main experiment findings. PMID:26324923

  2. Collective specification of cellular development.

    PubMed

    Sachs, Tsvi

    2003-09-01

    Studies of chimeras and in vivo development demonstrate that cell lineages are often quite variable, apparently in response to chance perturbations. This points to an apparent contradiction: although individual cells are the units of genetic information and differentiation, not all cellular events need be precise for the development of functional organisms. The social organization of ants can serve as a metaphor that helps understand the mechanisms that underlie such development. Ants suggest that continued cellular interactions and environmental conditions could specify the proportion and general location of specialized units. Leaf venation is used as a concrete example of this general principle. A signal produced continuously by all cells specifies a requirement for vein differentiation. The cells that respond by differentiation then transport the signal away from the leaf; this removal acting as a feedback indicating that the requirement is being met. Because transport increases during vein differentiation, early initiation occurs in excess and vein 'competition' for the signal assures an acceptable outcome. Such specification would be robust since it does not depend on events in any single cell, and chance events, rather than being corrected or reversed, may be built upon in reaching an expected, collective phenotype. The absence of detailed information preceding development distinguishes this hypothesis from the common alternatives of a program or blueprint. Collective specification would have important implications for developmental plasticity and evolution. PMID:12938179

  3. Cellular uptake of metallated cobalamins.

    PubMed

    Tran, Mai Thanh Quynh; Stürup, Stefan; Lambert, Ian Henry; Gammelgaard, Bente; Furger, Evelyne; Alberto, Roger

    2016-03-16

    Cellular uptake of vitamin B12-cisplatin conjugates was estimated via detection of their metal constituents (Co, Pt, and Re) by inductively coupled plasma mass spectrometry (ICP-MS). Vitamin B12 (cyano-cob(iii)alamin) and aquo-cob(iii)alamin [Cbl-OH2](+), which differ in the β-axial ligands (CN(-) and H2O, respectively), were included as control samples. The results indicated that B12 derivatives delivered cisplatin to both cellular cytosol and nuclei with an efficiency of one third compared to the uptake of free cisplatin cis-[Pt(II)Cl2(NH3)2]. In addition, uptake of charged B12 derivatives including [Cbl-OH2](+), [{Co}-CN-{cis-PtCl(NH3)2}](+), [{Re}-{Co}-CN-{cis-PtCl(NH3)2}](+), and [{Co}-CN-{trans-Pt(Cyt)(NH3)2}](2+) (Cyt = cytarabin) was high compared to neutral B12, which implied the existence of an additional internalization pathway for charged B12 vitamin analogs. The affinities of the charged B12 derivatives to the B12 transporters HC, IF and TC were similar to that of native vitamin B12. PMID:26739575

  4. Cellular Therapy for Heart Failure.

    PubMed

    Psaltis, Peter J; Schwarz, Nisha; Toledo-Flores, Deborah; Nicholls, Stephen J

    2016-01-01

    The pathogenesis of cardiomyopathy and heart failure (HF) is underpinned by complex changes at subcellular, cellular and extracellular levels in the ventricular myocardium. For all of the gains that conventional treatments for HF have brought to mortality and morbidity, they do not adequately address the loss of cardiomyocyte numbers in the remodeling ventricle. Originally conceived to address this problem, cellular transplantation for HF has already gone through several stages of evolution over the past two decades. Various cell types and delivery routes have been implemented to positive effect in preclinical models of ischemic and nonischemic cardiomyopathy, with pleiotropic benefits observed in terms of myocardial remodeling, systolic and diastolic performance, perfusion, fibrosis, inflammation, metabolism and electrophysiology. To a large extent, these salubrious effects are now attributed to the indirect, paracrine capacity of transplanted stem cells to facilitate endogenous cardiac repair processes. Promising results have also followed in early phase human studies, although these have been relatively modest and somewhat inconsistent. This review details the preclinical and clinical evidence currently available regarding the use of pluripotent stem cells and adult-derived progenitor cells for cardiomyopathy and HF. It outlines the important lessons that have been learned to this point in time, and balances the promise of this exciting field against the key challenges and questions that still need to be addressed at all levels of research, to ensure that cell therapy realizes its full potential by adding to the armamentarium of HF management. PMID:27280304

  5. CELLULAR PATHOGENESIS OF DIABETIC GASTROENTEROPATHY

    PubMed Central

    Ördög, Tamás; Hayashi, Yujiro; Gibbons, Simon J.

    2010-01-01

    SUMMARY Gastroenteropathy manifesting in upper gastrointestinal symptoms, delayed gastric emptying, constipation, diarrhea and fecal incontinence occurs frequently in patients with diabetes mellitus and represents a significant health care burden. Current treatments are largely symptomatic and ineffective. Better understanding of the cellular and molecular pathogenesis of these disorders is required for the development of more effective therapies. Recent advances in our understanding of the inherent, high-level complexities of the control systems that execute and regulate gastrointestinal motility, together with the utilization of new experimental models and sophisticated physiological, morphological and molecular techniques have lead to the realization that diabetic gastroenteropathies cannot be ascribed to any singular defect or dysfunction. In fact, these disorders are multifactorial and involve a spectrum of metabolic and dystrophic changes that can potentially affect all key components of motor control including the systemic autonomic and enteric nervous systems, interstitial cells of Cajal and smooth muscle cells. Candidate pathomechanisms are also varied and include imbalance between pro- and anti-oxidative factors, altered trophic stimuli to mature cells and their progenitors, and, possibly, autoimmune factors. The goal of this paper is to review the cellular changes underlying diabetic gastroenteropathies and their potential causes, with particular focus on functional interactions between various cell types. It is proposed that diabetic gastroenteropathies should be considered a form of gastrointestinal neuromuscular dystrophy rather than a “functional” disorder. Future research should identify ways to block cytotoxic factors, support the regeneration of damaged cells and translate the experimental findings into new treatment modalities. PMID:19829287

  6. Final Words

    ERIC Educational Resources Information Center

    Bers, Trudy

    2012-01-01

    This final chapter provides observations about institutional research in community colleges derived from the preceding chapters and the issue editors' own experiences. Taken as a whole, the chapters in this issue, as well as the editors' experiences, suggest several observations about institutional research in community colleges. These include the…

  7. Cellular Host Responses to Gliomas

    PubMed Central

    Barish, Michael E.; Garcia, Elizabeth; Metz, Marianne Z.; Myers, Sarah M.; Gutova, Margarita; Frank, Richard T.; Miletic, Hrvoje; Kendall, Stephen E.; Glackin, Carlotta A.; Bjerkvig, Rolf; Aboody, Karen S.

    2012-01-01

    Background Glioblastoma multiforme (GBM) is the most aggressive type of malignant primary brain tumors in adults. Molecular and genetic analysis has advanced our understanding of glioma biology, however mapping the cellular composition of the tumor microenvironment is crucial for understanding the pathology of this dreaded brain cancer. In this study we identified major cell populations attracted by glioma using orthotopic rodent models of human glioma xenografts. Marker-specific, anatomical and morphological analyses revealed a robust influx of host cells into the main tumor bed and tumor satellites. Methodology/Principal Findings Human glioma cell lines and glioma spheroid orthotopic implants were used in rodents. In both models, the xenografts recruited large numbers of host nestin-expressing cells, which formed a ‘network’ with glioma. The host nestin-expressing cells appeared to originate in the subventricular zone ipsilateral to the tumor, and were clearly distinguishable from pericytes that expressed smooth muscle actin. These distinct cell populations established close physical contact in a ‘pair-wise’ manner and migrated together to the deeper layers of tumor satellites and gave rise to tumor vasculature. The GBM biopsy xenografts displayed two different phenotypes: (a) low-generation tumors (first in vivo passage in rats) were highly invasive and non-angiogenic, and host nestin-positive cells that infiltrated into these tumors displayed astrocytic or elongated bipolar morphology; (b) high-generation xenografts (fifth passage) had pronounced cellularity, were angiogenic with ‘glomerulus-like’ microvascular proliferations that contained host nestin-positive cells. Stromal cell-derived factor-1 and its receptor CXCR4 were highly expressed in and around glioma xenografts, suggesting their role in glioma progression and invasion. Conclusions/Significance Our data demonstrate a robust migration of nestin-expressing host cells to glioma, which

  8. A Cellular GWAS Approach to Define Human Variation in Cellular Pathways Important to Inflammation.

    PubMed

    Miller, Samuel I; Chaudhary, Anu

    2016-01-01

    An understanding of common human diversity in innate immune pathways should be beneficial in understanding autoimmune diseases, susceptibility to infection, and choices of anti-inflammatory treatment. Such understanding could also result in definition of currently unknown components of human inflammation pathways. A cellular genome-wide association studies (GWAS) platform, termed Hi-HOST (High-throughput human in vitro susceptibility testing), was developed to assay in vitro cellular phenotypes of infection in genotyped lymphoblastoid cells from genetically diverse human populations. Hi-HOST allows for measurement of multiple host and pathogen parameters of infection/inflammation including: bacterial invasion and intracellular replication, host cell death, and cytokine production. Hi-HOST has been used to successfully define a significant portion of the heritable human diversity in inflammatory cell death in response to Salmonella typhimurium. It also led to the discovery of genetic variants important to protection against systemic inflammatory response syndrome (SIRS) and protection against death and bacteremia in individuals with SIRS. Our laboratory is currently using this platform to define human diversity in autophagy and the NLPR3 inflammasome pathways, and to define new components that can impact the expression of phenotypes related to these pathways. PMID:27128945

  9. A Cellular GWAS Approach to Define Human Variation in Cellular Pathways Important to Inflammation

    PubMed Central

    Miller, Samuel I.; Chaudhary, Anu

    2016-01-01

    An understanding of common human diversity in innate immune pathways should be beneficial in understanding autoimmune diseases, susceptibility to infection, and choices of anti-inflammatory treatment. Such understanding could also result in definition of currently unknown components of human inflammation pathways. A cellular genome-wide association studies (GWAS) platform, termed Hi-HOST (High-throughput human in vitro susceptibility testing), was developed to assay in vitro cellular phenotypes of infection in genotyped lymphoblastoid cells from genetically diverse human populations. Hi-HOST allows for measurement of multiple host and pathogen parameters of infection/inflammation including: bacterial invasion and intracellular replication, host cell death, and cytokine production. Hi-HOST has been used to successfully define a significant portion of the heritable human diversity in inflammatory cell death in response to Salmonella typhimurium. It also led to the discovery of genetic variants important to protection against systemic inflammatory response syndrome (SIRS) and protection against death and bacteremia in individuals with SIRS. Our laboratory is currently using this platform to define human diversity in autophagy and the NLPR3 inflammasome pathways, and to define new components that can impact the expression of phenotypes related to these pathways. PMID:27128945

  10. Optimal flux patterns in cellular metabolic networks

    SciTech Connect

    Almaas, E

    2007-01-20

    The availability of whole-cell level metabolic networks of high quality has made it possible to develop a predictive understanding of bacterial metabolism. Using the optimization framework of flux balance analysis, I investigate metabolic response and activity patterns to variations in the availability of nutrient and chemical factors such as oxygen and ammonia by simulating 30,000 random cellular environments. The distribution of reaction fluxes is heavy-tailed for the bacteria H. pylori and E. coli, and the eukaryote S. cerevisiae. While the majority of flux balance investigations have relied on implementations of the simplex method, it is necessary to use interior-point optimization algorithms to adequately characterize the full range of activity patterns on metabolic networks. The interior-point activity pattern is bimodal for E. coli and S. cerevisiae, suggesting that most metabolic reaction are either in frequent use or are rarely active. The trimodal activity pattern of H. pylori indicates that a group of its metabolic reactions (20%) are active in approximately half of the simulated environments. Constructing the high-flux backbone of the network for every environment, there is a clear trend that the more frequently a reaction is active, the more likely it is a part of the backbone. Finally, I briefly discuss the predicted activity patterns of the central-carbon metabolic pathways for the sample of random environments.

  11. Optimal flux patterns in cellular metabolic networks

    NASA Astrophysics Data System (ADS)

    Almaas, Eivind

    2007-06-01

    The availability of whole-cell-level metabolic networks of high quality has made it possible to develop a predictive understanding of bacterial metabolism. Using the optimization framework of flux balance analysis, I investigate the metabolic response and activity patterns to variations in the availability of nutrient and chemical factors such as oxygen and ammonia by simulating 30 000 random cellular environments. The distribution of reaction fluxes is heavy tailed for the bacteria H. pylori and E. coli, and the eukaryote S. cerevisiae. While the majority of flux balance investigations has relied on implementations of the simplex method, it is necessary to use interior-point optimization algorithms to adequately characterize the full range of activity patterns on metabolic networks. The interior-point activity pattern is bimodal for E. coli and S. cerevisiae, suggesting that most metabolic reactions are either in frequent use or are rarely active. The trimodal activity pattern of H. pylori indicates that a group of its metabolic reactions (20%) are active in approximately half of the simulated environments. Constructing the high-flux backbone of the network for every environment, there is a clear trend that the more frequently a reaction is active, the more likely it is a part of the backbone. Finally, I briefly discuss the predicted activity patterns of the central carbon metabolic pathways for the sample of random environments.

  12. Cellular and molecular mechanisms in liver fibrogenesis.

    PubMed

    Novo, Erica; Cannito, Stefania; Paternostro, Claudia; Bocca, Claudia; Miglietta, Antonella; Parola, Maurizio

    2014-04-15

    Liver fibrogenesis is a dynamic and highly integrated molecular, tissue and cellular process, potentially reversible, that drives the progression of chronic liver diseases (CLD) towards liver cirrhosis and hepatic failure. Hepatic myofibroblasts (MFs), the pro-fibrogenic effector cells, originate mainly from activation of hepatic stellate cells and portal fibroblasts being characterized by a proliferative and survival attitude. MFs also contract in response to vasoactive agents, sustain angiogenesis and recruit and modulate activity of cells of innate or adaptive immunity. Chronic activation of wound healing and oxidative stress as well as derangement of epithelial-mesenchymal interactions are "major" pro-fibrogenic mechanisms, whatever the etiology. However, literature has outlined a complex network of pro-fibrogenic factors and mediators proposed to modulate CLD progression, with some of them being at present highly debated in the field, including the role of epithelial to mesenchymal transition and Hedgehog signaling pathways. Hypoxia and angiogenesis as well as inflammasomes are recently emerged as ubiquitous pro-inflammatory and pro-fibrogenic determinants whereas adipokines are mostly involved in CLD related to metabolic disturbances (metabolic syndrome and/or obesity and type 2 diabetes). Finally, autophagy as well as natural killer and natural killer-T cells have been recently proposed to significantly affect fibrogenic CLD progression. PMID:24631571

  13. Thermomechanical characterisation of cellular rubber

    NASA Astrophysics Data System (ADS)

    Seibert, H.; Scheffer, T.; Diebels, S.

    2016-01-01

    This contribution discusses an experimental possibility to characterise a cellular rubber in terms of the influence of multiaxiality, rate dependency under environmental temperature and its behaviour under hydrostatic pressure. In this context, a mixed open and closed cell rubber based on an ethylene propylene diene monomer is investigated exemplarily. The present article intends to give a general idea of the characterisation method and the considerable effects of this special type of material. The main focus lies on the experimental procedure and the used testing devices in combination with the analysis methods such as true three-dimensional digital image correlation. The structural compressibility is taken into account by an approach for a material model using the Theory of Porous Media with additional temperature dependence.

  14. [Cellular pathology of neurodegenerative disorders].

    PubMed

    Wakabayashi, Koichi

    2013-01-01

    Common cellular and molecular mechanisms including protein aggregation and inclusion body formation are involved in many neurodegenerative diseases. α-Synuclein is a major component of Lewy bodies in Parkinson's disease (PD) as well as in glial cytoplasmic inclusions in multiple system atrophy (MSA). Tau is a principal component of neurofibrillary and glial tangles in tauopathies. Recently, TDP-43 was identified as a component of ubiquitinated inclusions in amyotrophic lateral sclerosis and frontotemporal lobar degeneration. PD is traditionally considered a movement disorder with hallmark lesions in the brainstem pigmented nuclei. However, pathological changes occur in widespread regions of the central and peripheral nervous systems in this disease. Furthermore, primary glial involvement ("gliodegeneration") can be observed in PD and MSA as well as in tauopathy. The present article reviews abnormal protein accumulation and inclusion body formation inside and outside the central nervous system. PMID:23965852

  15. Regulation of cellular chromatin state

    PubMed Central

    Mishra, Rakesh K; Dhawan, Jyotsna

    2010-01-01

    The identity and functionality of eukaryotic cells is defined not just by their genomic sequence which remains constant between cell types, but by their gene expression profiles governed by epigenetic mechanisms. Epigenetic controls maintain and change the chromatin state throughout development, as exemplified by the setting up of cellular memory for the regulation and maintenance of homeotic genes in proliferating progenitors during embryonic development. Higher order chromatin structure in reversibly arrested adult stem cells also involves epigenetic regulation and in this review we highlight common trends governing chromatin states, focusing on quiescence and differentiation during myogenesis. Together, these diverse developmental modules reveal the dynamic nature of chromatin regulation providing fresh insights into the role of epigenetic mechanisms in potentiating development and differentiation. PMID:20592864

  16. Cellular compartmentalization of secondary metabolism

    PubMed Central

    Kistler, H. Corby; Broz, Karen

    2015-01-01

    Fungal secondary metabolism is often considered apart from the essential housekeeping functions of the cell. However, there are clear links between fundamental cellular metabolism and the biochemical pathways leading to secondary metabolite synthesis. Besides utilizing key biochemical precursors shared with the most essential processes of the cell (e.g., amino acids, acetyl CoA, NADPH), enzymes for secondary metabolite synthesis are compartmentalized at conserved subcellular sites that position pathway enzymes to use these common biochemical precursors. Co-compartmentalization of secondary metabolism pathway enzymes also may function to channel precursors, promote pathway efficiency and sequester pathway intermediates and products from the rest of the cell. In this review we discuss the compartmentalization of three well-studied fungal secondary metabolite biosynthetic pathways for penicillin G, aflatoxin and deoxynivalenol, and summarize evidence used to infer subcellular localization. We also discuss how these metabolites potentially are trafficked within the cell and may be exported. PMID:25709603

  17. Force generation by cellular motors.

    PubMed

    Wanka, Friedrich; Van Zoelen, Everardus J J

    2003-01-01

    Cell motility processes in non-muscle cells depend on the activity of motor proteins that bind to either microtubules or actin filaments. From presently available data it must be concluded that the driving force is generated by transient interaction of the respective motors with microtubules or actin filaments which then activates the binding and hydrolysis of ATP. This reaction results in an abrupt discharge of the motor molecule, the direction of which is determined by the spatial orientation of its binding to the helical and polar vehicle. The latter is thereby propelled in its length direction and simultaneously undergoes an axial rotation, while the expelled motor exerts an oppositely directed current in the surrounding fluid, comparable to jet propulsion. Force production, propulsion velocities and energy requirements known from in vitro studies comply with those derived from the theory. The theory opens new ways for the understanding of cellular activities such as particle transport, mitosis and morphodynamics. PMID:14668925

  18. Pressure-actuated cellular structures.

    PubMed

    Pagitz, M; Lamacchia, E; Hol, J M A M

    2012-03-01

    Shape changing structures will play an important role in future engineering designs since rigid structures are usually only optimal for a small range of service conditions. Hence, a concept for reliable and energy-efficient morphing structures that possess a large strength to self-weight ratio would be widely applicable. We propose a novel concept for morphing structures that is inspired by the nastic movement of plants. The idea is to connect prismatic cells with tailored pentagonal and/or hexagonal cross sections such that the resulting cellular structure morphs into given target shapes for certain cell pressures. An efficient algorithm for computing equilibrium shapes as well as cross-sectional geometries is presented. The potential of this novel concept is demonstrated by several examples that range from a flagellum like propulsion device to a morphing aircraft wing. PMID:22278936

  19. Cellular ageing mechanisms in osteoarthritis.

    PubMed

    Sacitharan, P K; Vincent, T L

    2016-08-01

    Age is the strongest independent risk factor for the development of osteoarthritis (OA) and for many years this was assumed to be due to repetitive microtrauma of the joint surface over time, the so-called 'wear and tear' arthritis. As our understanding of OA pathogenesis has become more refined, it has changed our appreciation of the role of ageing on disease. Cartilage breakdown in disease is not a passive process but one involving induction and activation of specific matrix-degrading enzymes; chondrocytes are exquisitely sensitive to changes in the mechanical, inflammatory and metabolic environment of the joint; cartilage is continuously adapting to these changes by altering its matrix. Ageing influences all of these processes. In this review, we will discuss how ageing affects tissue structure, joint use and the cellular metabolism. We describe what is known about pathways implicated in ageing in other model systems and discuss the potential value of targeting these pathways in OA. PMID:27215642

  20. Cellular tolerance to pulsed heating

    NASA Astrophysics Data System (ADS)

    Simanovski, Dimitrii; Sarkar, M.; Irani, A.; O'Connell-Rodwell, C.; Contag, C.; Schwettman, H. Alan; Palanker, D.

    2005-04-01

    Many laser therapies involve significant heating of tissue with pulses varying from picoseconds to minutes in duration. In some of the applications heating is a primary goal, while in others it is an undesirable side effect. In both cases, if a hyperthermia is involved, the knowledge about the threshold temperature leading to irreversible cellular damage is critically important. We study the dependence of the threshold temperature on duration of the heat exposure in the range of 0.3 ms to 5 seconds. Thin layer of cells cultured in a Petri dish was exposed to a pulsed CO2 laser radiation. Laser beam was focused onto sample providing Gaussian intensity distribution in the focal plane with a beam diameter (2w) 2-10 mm. Surface temperature in the central part of the focal spot (1mm in diameter) was measured by thermal infrared (IR) emission from the sample, recorded with a fast IR detector. For pulses shorter than 1 s the temperature profile across the focal spot was found to closely correspond to the radial distribution of the laser beam intensity, thus allowing for accurate determination of temperature at any given distance from the center of the spot. Immediate cellular damage was assessed using vital staining with the live/dead fluorescent assay. Threshold temperatures were found to vary from 65 °C at 5 s of heating to 160 °C at pulses of 0.3 ms in duration. The shorter end of this range was limited by vaporization, which occurs during the laser pulse and results in mechanical damage to cells. Dependence of the maximal temperature on pulse duration could be approximated by Arrhenius law with activation energy being about 1 eV.

  1. Fundamental Limits to Cellular Sensing

    NASA Astrophysics Data System (ADS)

    ten Wolde, Pieter Rein; Becker, Nils B.; Ouldridge, Thomas E.; Mugler, Andrew

    2016-03-01

    In recent years experiments have demonstrated that living cells can measure low chemical concentrations with high precision, and much progress has been made in understanding what sets the fundamental limit to the precision of chemical sensing. Chemical concentration measurements start with the binding of ligand molecules to receptor proteins, which is an inherently noisy process, especially at low concentrations. The signaling networks that transmit the information on the ligand concentration from the receptors into the cell have to filter this receptor input noise as much as possible. These networks, however, are also intrinsically stochastic in nature, which means that they will also add noise to the transmitted signal. In this review, we will first discuss how the diffusive transport and binding of ligand to the receptor sets the receptor correlation time, which is the timescale over which fluctuations in the state of the receptor, arising from the stochastic receptor-ligand binding, decay. We then describe how downstream signaling pathways integrate these receptor-state fluctuations, and how the number of receptors, the receptor correlation time, and the effective integration time set by the downstream network, together impose a fundamental limit on the precision of sensing. We then discuss how cells can remove the receptor input noise while simultaneously suppressing the intrinsic noise in the signaling network. We describe why this mechanism of time integration requires three classes (groups) of resources—receptors and their integration time, readout molecules, energy—and how each resource class sets a fundamental sensing limit. We also briefly discuss the scheme of maximum-likelihood estimation, the role of receptor cooperativity, and how cellular copy protocols differ from canonical copy protocols typically considered in the computational literature, explaining why cellular sensing systems can never reach the Landauer limit on the optimal trade

  2. Role of cellular communication in the pathways of radiation-induced biological damage

    NASA Astrophysics Data System (ADS)

    Ballarini, Francesca; Facoetti, Angelica; Mariotti, Luca; Nano, Rosanna; Ottolenghi, Andrea

    During the last decade, a large number of experimental studies on the so-called "non-targeted effects", in particular bystander effects, outlined that cellular communication plays a signifi- cant role in the pathways leading to radiation-induced biological damage. This might imply a paradigm shift in (low-dose) radiobiology, according to which one has to consider the response of groups of cells behaving like a population rather than single cells behaving as individuals. Furthermore, bystander effects, which are observed both for lethal endpoints (e.g. clonogenic inactivation and apoptosis) and for non-lethal ones (e.g. mutations and neoplastic transformation), tend to show non-linear dose responses characterized by a sharp increase followed by a plateau. This might have significant consequences in terms of low-dose risk, which is generally calculated on the basis of the "Linear No Threshold" hypothesis. Although it is known that two types of cellular communication (i.e. via gap junctions and/or molecular messengers diffusing in the extra-cellular environment, such as cytokines) play a major role, it is of utmost importance to better understand the underlying mechanisms, and how such mechanisms can be modulated by ionizing radiation. Though the "final" goal is to elucidate the in vivo scenario, in the meanwhile also in vitro studies can provide useful insights. In the present paper we will discuss key issues on the mechanisms underlying non-targeted effects and, more generally, cell communication, with focus on candidate molecular signals. Theoretical models and simulation codes can be of help in elucidating such mechanisms. In this framework, we will present a model and Monte Carlo code, under development at the University of Pavia, simulating the release, diffusion and internalization of candidate signals (typically cytokines) travelling in the extra-cellular environment, both by unirradiated (i.e., control) cells and by irradiated cells. The focus will be on the

  3. Final Report

    SciTech Connect

    R. Paul Drake

    2001-11-30

    This final report describes work involving 22 investigators from 11 institutions to explore the dynamics present in supernova explosions by means of experiments on the Omega laser. The specific experiments emphasized involved the unstable expansion of a spherical capsule and the coupling of perturbations at a first interface to a second interface by means of a strong shock. Both effects are present in supernovae. The experiments were performed at Omega and the computer simulations were undertaken at several institutions. B139

  4. Final Report

    SciTech Connect

    Marchant, Gary E.

    2013-04-23

    This is the final report of a two year project entitled "Governing Nanotechnology Risks and Benefits in the Transition to Regulation: Innovative Public and Private Approaches." This project examined the role of new governance or "soft law" mechanisms such as codes of conduct, voluntary programs and partnership agreements to manage the risks of emerging technologies such as nanotechnology. A series of published or in publication papers and book chapters are attached.

  5. Protein Targeting and Transport as a Necessary Consequence of Increased Cellular Complexity

    PubMed Central

    Sommer, Maik S.; Schleiff, Enrico

    2014-01-01

    With increasing intracellular complexity, a new cell-biological problem that is the allocation of cytoplasmically synthesized proteins to their final destinations within the cell emerged. A special challenge is thereby the translocation of proteins into or across cellular membranes. The underlying mechanisms are only in parts well understood, but it can be assumed that the course of cellular evolution had a deep impact on the design of the required molecular machines. In this article, we aim to summarize the current knowledge and concepts of the evolutionary development of protein trafficking as a necessary premise and consequence of increased cellular complexity. PMID:25085907

  6. Anti-Aging Strategies Based on Cellular Reprogramming.

    PubMed

    Ocampo, Alejandro; Reddy, Pradeep; Izpisua Belmonte, Juan Carlos

    2016-08-01

    Aging can be defined as the progressive decline in the ability of a cell or organism to resist stress and disease. Recent advances in cellular reprogramming technologies have enabled detailed analyses of the aging process, often involving cell types derived from aged individuals, or patients with premature aging syndromes. In this review we discuss how cellular reprogramming allows the recapitulation of aging in a dish, describing novel experimental approaches to investigate the aging process. Finally, we explore the role of epigenetic dysregulation as a driver of aging, discussing how epigenetic reprogramming may be harnessed to ameliorate aging hallmarks, both in vitro and in vivo. A better understanding of the reprogramming process may indeed assist the development of novel therapeutic strategies to extend a healthy lifespan. PMID:27426043

  7. A palette of fluorescent proteins optimized for diverse cellular environments

    PubMed Central

    Costantini, Lindsey M.; Baloban, Mikhail; Markwardt, Michele L.; Rizzo, Mark; Guo, Feng; Verkhusha, Vladislav V.; Snapp, Erik L.

    2015-01-01

    To perform quantitative live cell imaging, investigators require fluorescent reporters that accurately report protein localization and levels, while minimally perturbing the cell. Yet, within the biochemically distinct environments of cellular organelles, popular fluorescent proteins (FPs), including EGFP, can be unreliable for quantitative imaging, resulting in underestimation of protein levels and incorrect localization. Specifically, within the secretory pathway, significant populations of FPs misfold and fail to fluoresce due to non-native disulphide bond formation. Furthermore, transmembrane FP fusion constructs can disrupt organelle architecture due to oligomerizing tendencies of numerous common FPs. Here, we describe a powerful set of bright and inert FPs optimized for use in multiple cellular compartments, especially oxidizing environments and biological membranes. Also, we provide new insights into use of red FPs in the secretory pathway. Our monomeric "oxFPs" finally resolve long standing, underappreciated, and important problems of cell biology and should be useful for a number of applications. PMID:26158227

  8. Optical information storage in cellular mobile terminals

    NASA Astrophysics Data System (ADS)

    Makela, Jakke S.; Aikio, Janne K.; Vadde, Venkatesh; Kolehmainen, Timo T.; Karioja, Pentti

    2001-11-01

    The trend towards so-called digital convergence (multiple functionality within a single terminal) is opening up a need for high-capacity storage within the cellular mobile terminals (CMT). Solid-state memories and magnetic microdrives are the most commercially mature options. Optical disk technology in this size range is immature, but has a unique potential: no other medium at present has the capability to be simultaneously low-cost, high-capacity, and exchangeable. In this paper, we explore the requirements for the implementation of optical disk storage in a CMT environment. From the technical point of view, these requirements include small form factor, high-enough data density and throughput, low power consumption, robustness, low cost, mass productability, and modularity. Although current technologies may satisfy some of these requirements individually, there is a need for combined optimization of all of these parameters. From the commercial point of view, the most crucial requirement is global standardization. Such standardization is crucial if wide interoperability is wanted (between CMT manufacturers, and even more crucially between CMTs and other appliances). Current optical storage standards are industry-driven and tend to be proprietary and/or incompatible. Even if the technical challenges can be met, optical data storage is not likely to be accepted in CMT applications unless global standardization proceeds more quickly than it is doing at present.

  9. Cellular-enabled water quality measurements

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Kerkez, B.

    2013-12-01

    While the past decade has seen significant improvements in our ability to measure nutrients and other water quality parameters, the use of these sensors has yet to gain traction due to their costprohibitive nature and deployment expertise required on the part of researchers. Furthermore, an extra burden is incurred when real-time data access becomes an experimental requirement. We present an open-source hardware design to facilitate the real-time, low-cost, and robust measurements of water quality across large urbanized areas. Our hardware platform interfaces an embedded, vastly configurable, high-precision, ultra-low power measurement system, with a low-power cellular module. Each sensor station is configured with an IP address, permitting reliable streaming of sensor data to off-site locations as measurements are made. We discuss the role of high-quality hardware components during extreme event scenarios, and present preliminary performance metrics that validate the ability of the platform to provide streaming access to sensor measurements.

  10. Cellular automata modelling of biomolecular networks dynamics.

    PubMed

    Bonchev, D; Thomas, S; Apte, A; Kier, L B

    2010-01-01

    The modelling of biological systems dynamics is traditionally performed by ordinary differential equations (ODEs). When dealing with intracellular networks of genes, proteins and metabolites, however, this approach is hindered by network complexity and the lack of experimental kinetic parameters. This opened the field for other modelling techniques, such as cellular automata (CA) and agent-based modelling (ABM). This article reviews this emerging field of studies on network dynamics in molecular biology. The basics of the CA technique are discussed along with an extensive list of related software and websites. The application of CA to networks of biochemical reactions is exemplified in detail by the case studies of the mitogen-activated protein kinase (MAPK) signalling pathway, the FAS-ligand (FASL)-induced and Bcl-2-related apoptosis. The potential of the CA method to model basic pathways patterns, to identify ways to control pathway dynamics and to help in generating strategies to fight with cancer is demonstrated. The different line of CA applications presented includes the search for the best-performing network motifs, an analysis of importance for effective intracellular signalling and pathway cross-talk. PMID:20373215