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Sample records for intestinal loop model

  1. Closed-Loop Doluisio (Colon, Small Intestine) and Single-Pass Intestinal Perfusion (Colon, Jejunum) in Rat-Biophysical Model and Predictions Based on Caco-2.

    Science.gov (United States)

    Lozoya-Agullo, Isabel; Gonzalez-Alvarez, Isabel; Zur, Moran; Fine-Shamir, Noa; Cohen, Yael; Markovic, Milica; Garrigues, Teresa M; Dahan, Arik; Gonzalez-Alvarez, Marta; Merino-Sanjuán, Matilde; Bermejo, Marival; Avdeef, Alex

    2017-12-29

    The effective rat intestinal permeability (P eff ) was deconvolved using a biophysical model based on parameterized paracellular, aqueous boundary layer, transcellular permeabilities, and the villus-fold surface area expansion factor. Four types of rat intestinal perfusion data were considered: single-pass intestinal perfusion (SPIP) in the jejunum (n = 40), and colon (n = 15), closed-loop (Doluisio type) in the small intestine (n = 78), and colon (n = 74). Moreover, in vitro Caco-2 permeability values were used to predict rat in vivo values in the rat data studied. Comparable number of molecules permeate via paracellular water channels as by the lipoidal transcellular route in the SPIP method, although in the closed-loop method, the paracellular route appears dominant in the colon. The aqueous boundary layer thickness in the small intestine is comparable to that found in unstirred in vitro monolayer assays; it is thinner in the colon. The mucosal surface area in anaesthetized rats is 0.96-1.4 times the smooth cylinder calculated value in the colon, and it is 3.1-3.6 times in the small intestine. The paracellular permeability of the intestine appeared to be greater in rat than human, with the colon showing more leakiness (higher P para ) than the small intestine. Based on log intrinsic permeability values, the correlations between the in vitro and in vivo models ranged from r 2 0.82 to 0.92. The SPIP-Doluisio method comparison indicated identical log permeability selectivity trend with negligible bias.

  2. Application of a pig ligated intestinal loop model for early Lawsonia intracellularis infection

    DEFF Research Database (Denmark)

    Boutrup, Torsten Snogdal; Schauser, Kirsten; Agerholm, Jørgen S

    2010-01-01

    (Enterisol® Ileitis Vet), and 3) vaccine bacteria propagated in cell culture. The bacteria-enterocyte interaction was visualised using immunohistochemistry on specimens derived 1, 3 and 6 h PI respectively. Results Although at a low level, close contact between bacteria and the enterocyte brush border...... including intracellular uptake of bacteria in mature enterocytes was seen at 3 and 6 h PI for the vaccine and the propagated vaccine inocula. Interaction between the wild-type bacteria and villus enterocytes was scarce and only seen at 6 h PI, where a few bacteria were found in close contact with the brush...... and that the bacterium, as shown for the vaccine bacteria, propagated as well as non-propagated, was able to invade mature enterocytes. Thus, the study demonstrates the early intestinal invasion of L. intracellularis in vivo....

  3. Modeling of compact loop antennas

    International Nuclear Information System (INIS)

    Baity, F.W.

    1987-01-01

    A general compact loop antenna model which treats all elements of the antenna as lossy transmission lines has been developed. In addition to capacitively-tuned resonant double loop (RDL) antennas the model treats stub-tuned resonant double loop antennas. Calculations using the model have been compared with measurements on full-scale mockups of resonant double loop antennas for ATF and TFTR in order to refine the transmission line parameters. Results from the model are presented for RDL antenna designs for ATF, TFTR, Tore Supra, and for the Compact Ignition Tokamak

  4. RCD+: Fast loop modeling server.

    Science.gov (United States)

    López-Blanco, José Ramón; Canosa-Valls, Alejandro Jesús; Li, Yaohang; Chacón, Pablo

    2016-07-08

    Modeling loops is a critical and challenging step in protein modeling and prediction. We have developed a quick online service (http://rcd.chaconlab.org) for ab initio loop modeling combining a coarse-grained conformational search with a full-atom refinement. Our original Random Coordinate Descent (RCD) loop closure algorithm has been greatly improved to enrich the sampling distribution towards near-native conformations. These improvements include a new workflow optimization, MPI-parallelization and fast backbone angle sampling based on neighbor-dependent Ramachandran probability distributions. The server starts by efficiently searching the vast conformational space from only the loop sequence information and the environment atomic coordinates. The generated closed loop models are subsequently ranked using a fast distance-orientation dependent energy filter. Top ranked loops are refined with the Rosetta energy function to obtain accurate all-atom predictions that can be interactively inspected in an user-friendly web interface. Using standard benchmarks, the average root mean squared deviation (RMSD) is 0.8 and 1.4 Å for 8 and 12 residues loops, respectively, in the challenging modeling scenario in where the side chains of the loop environment are fully remodeled. These results are not only very competitive compared to those obtained with public state of the art methods, but also they are obtained ∼10-fold faster. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

  5. Stagnant loop syndrome resulting from small-bowel irradiation injury and intestinal by-pass

    International Nuclear Information System (INIS)

    Swan, R.W.

    1974-01-01

    Stagnant or blind-loop syndrome includes vitamin B12 malabsorption, steatorrhea, and bacterial overgrowth of the small intestine. A case is presented to demonstrate this syndrome occurring after small-bowel irradiation injury with exaggeration postenterocolic by-pass. Alteration of normal small-bowel flora is basic to development of the stagnant-loop syndrome. Certain strains of bacteria as Bacteriodes and E. coli are capable of producing a malabsorption state. Definitive therapy for this syndrome developing after severe irradiation injury and intestinal by-pass includes antibiotics. Rapid symptomatic relief from diarrhea and improved malabsorption studies usually follow appropriate antibiotic therapy. Recolonization of the loop(s) with the offending bacterial species may produce exacerbation of symptoms. Since antibiotics are effective, recognition of this syndrome is important. Foul diarrheal stools should not be considered a necessary consequence of irradiation injury and intestinal by-pass

  6. Modeling intestinal disorders using zebrafish.

    Science.gov (United States)

    Zhao, X; Pack, M

    2017-01-01

    Although the zebrafish was initially developed as a model system to study embryonic development, it has gained increasing attention as an advantageous system to investigate human diseases, including intestinal disorders. Zebrafish embryos develop rapidly, and their digestive system is fully functional and visible by 5days post fertilization. There is a large degree of homology between the intestine of zebrafish and higher vertebrate organisms in terms of its cellular composition and function as both a digestive and immune organ. Furthermore, molecular pathways regulating injury and immune responses are highly conserved. In this chapter, we provide an overview of studies addressing developmental and physiological processes relevant to human intestinal disease. These studies include those related to congenital disorders, host-microbiota interactions, inflammatory diseases, motility disorders, and intestinal cancer. We also highlight the utility of zebrafish to functionally validate candidate genes identified through mutational analyses and genome-wide association studies, and discuss methodologies to investigate the intestinal biology that are unique to zebrafish. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. The WZNW Model at Two Loops

    NARCIS (Netherlands)

    Wit, B. de; Grisaru, M. T.; Nieuwenhuizen, P. van

    1993-01-01

    We study perturbatively the (conformal) WZNW model. At one loop we compute one-particle irreducible two- and three-point current correlation functions, both in the conventional version and in the classically equivalent, chiral, nonlocal, induced version of the model. At two loops we compute the

  8. The TNO gastro-intestinal model (TIM)

    NARCIS (Netherlands)

    Minekus, M.

    2015-01-01

    The TNO Gastro–Intestinal Model (TIM) is a multi–compartmental model, designed to realistically simulate conditions in the lumen of the gastro–intestinal tract. TIM is successfully used to study the gastro–intestinal behavior of a wide variety of feed, food and pharmaceutical products. Experiments

  9. Mathematical Modeling of Loop Heat Pipes

    Science.gov (United States)

    Kaya, Tarik; Ku, Jentung; Hoang, Triem T.; Cheung, Mark L.

    1998-01-01

    The primary focus of this study is to model steady-state performance of a Loop Heat Pipe (LHP). The mathematical model is based on the steady-state energy balance equations at each component of the LHP. The heat exchange between each LHP component and the surrounding is taken into account. Both convection and radiation environments are modeled. The loop operating temperature is calculated as a function of the applied power at a given loop condition. Experimental validation of the model is attempted by using two different LHP designs. The mathematical model is tested at different sink temperatures and at different elevations of the loop. Tbc comparison of the calculations and experimental results showed very good agreement (within 3%). This method proved to be a useful tool in studying steady-state LHP performance characteristics.

  10. Sigma models and renormalization of string loops

    International Nuclear Information System (INIS)

    Tseytlin, A.A.

    1989-05-01

    An extension of the ''σ-model β-functions - string equations of motion'' correspondence to the string loop level is discussed. Special emphasis is made on how the renormalization group acts in string loops and, in particular, on the renormalizability property of the generating functional Z-circumflex for string amplitudes (related to the σ model partition function integrated over moduli). Renormalization of Z-circumflex at one and two loop order is analyzed in some detail. We also discuss an approach to renormalization based on operators of insertion of topological fixtures. (author). 70 refs

  11. Combinatorial aspects of boundary loop models

    International Nuclear Information System (INIS)

    Lykke Jacobsen, Jesper; Saleur, Hubert

    2008-01-01

    We discuss in this paper combinatorial aspects of boundary loop models, that is models of self-avoiding loops on a strip where loops get different weights depending on whether they touch the left, the right, both or no boundary. These models are described algebraically by a generalization of the Temperley–Lieb algebra, dubbed the two-boundary TL algebra. We give results for the dimensions of TL representations and the corresponding degeneracies in the partition functions. We interpret these results in terms of fusion and in the light of the recently uncovered A n large symmetry present in loop models, paving the way for the analysis of the conformal field theory properties. Finally, we propose conjectures for determinants of Gram matrices in all cases, including the two-boundary one, which has recently been discussed by de Gier and Nichols

  12. Comprehensive study of the intestinal stage of listeriosis in a rat ligated ileal loop system.

    Science.gov (United States)

    Pron, B; Boumaila, C; Jaubert, F; Sarnacki, S; Monnet, J P; Berche, P; Gaillard, J L

    1998-02-01

    The intestinal stage of listeriosis was studied in a rat ligated ileal loop system. Listeria monocytogenes translocated to deep organs with similar efficiencies after inoculation of loops with or without Peyer's patches. Bacterial seeding of deep organs was demonstrated as early as 15 min after inoculation. It was dose dependent and nonspecific, as the delta inlAB, the delta hly, and the delta actA L. monocytogenes mutants and the nonpathogenic species, Listeria innocua, translocated similarly to wild-type L. monocytogenes strains. The levels of uptake of listeriae by Peyer's patches and villous intestine were similar and low, 50 to 250 CFU per cm2 of tissue. No listeria cells crossing the epithelial sheet of Peyer's patches and villous intestine were observed by transmission electron microscopy. The lack of significant interaction of listeriae and the follicle-associated epithelium of Peyer's patches was confirmed by scanning electron microscopy. The follicular tissue of Peyer's patches was a preferential site of Listeria replication. With all doses tested, the rate of bacterial growth was 10 to 20 times higher in Peyer's patches than in villous intestine. At early stages of Peyer's patch infection, listeriae were observed inside mononuclear cells of the dome area. Listeriae then disseminated throughout the follicular tissue except for the germinal center. The virulence determinants hly and, to a lesser extent, actA, but not inlAB, were required for the completion of this process. This study suggests that Peyer's patches are preferential sites for replication rather than for entry of L. monocytogenes, due to the presence of highly permissive mononuclear cells whose nature remains to be defined.

  13. Jordan cells of periodic loop models

    International Nuclear Information System (INIS)

    Morin-Duchesne, Alexi; Saint-Aubin, Yvan

    2013-01-01

    Jordan cells in transfer matrices of finite lattice models are a signature of the logarithmic character of the conformal field theories that appear in their thermodynamical limit. The transfer matrix of periodic loop models, T N , is an element of the periodic Temperley–Lieb algebra EPTL N (β,α), where N is the number of sites on a section of the cylinder, and β = −q − q −1 = 2cos λ and α the weights of contractible and non-contractible loops. The thermodynamic limit of T N is believed to describe a conformal field theory of central charge c = 1 − 6λ 2 /(π(λ − π)). The abstract element T N acts naturally on (a sum of) spaces V-tilde N d , similar to those upon which the standard modules of the (classical) Temperley–Lieb algebra act. These spaces known as sectors are labeled by the numbers of defects d and depend on a twist parameter v that keeps track of the winding of defects around the cylinder. Criteria are given for non-trivial Jordan cells of T N both between sectors with distinct defect numbers and within a given sector. (paper)

  14. Pig models on intestinal development and therapeutics.

    Science.gov (United States)

    Yin, Lanmei; Yang, Huansheng; Li, Jianzhong; Li, Yali; Ding, Xueqing; Wu, Guoyao; Yin, Yulong

    2017-12-01

    The gastrointestinal tract plays a vital role in nutrient supply, digestion, and absorption, and has a crucial impact on the entire organism. Much attention is being paid to utilize animal models to study the pathogenesis of gastrointestinal diseases in response to intestinal development and health. The piglet has a body size similar to that of the human and is an omnivorous animal with comparable anatomy, nutritional requirements, and digestive and associated inflammatory processes, and displays similarities to the human intestinal microbial ecosystem, which make piglets more appropriate as an animal model for human than other non-primate animals. Therefore, the objective of this review is to summarize key attributes of the piglet model with which to study human intestinal development and intestinal health through probing into the etiology of several gastrointestinal diseases, thus providing a theoretical and hopefully practical, basis for further studies on mammalian nutrition, health, and disease, and therapeutics. Given the comparable nutritional requirements and strikingly similar brain developmental patterns between young piglets and humans, the piglet has been used as an important translational model for studying neurodevelopmental outcomes influenced by pediatric nutrition. Because of similarities in anatomy and physiology between pigs and mankind, more emphasises are put on how to use the piglet model for human organ transplantation research.

  15. Fast loop modeling for protein structures

    Science.gov (United States)

    Zhang, Jiong; Nguyen, Son; Shang, Yi; Xu, Dong; Kosztin, Ioan

    2015-03-01

    X-ray crystallography is the main method for determining 3D protein structures. In many cases, however, flexible loop regions of proteins cannot be resolved by this approach. This leads to incomplete structures in the protein data bank, preventing further computational study and analysis of these proteins. For instance, all-atom molecular dynamics (MD) simulation studies of structure-function relationship require complete protein structures. To address this shortcoming, we have developed and implemented an efficient computational method for building missing protein loops. The method is database driven and uses deep learning and multi-dimensional scaling algorithms. We have implemented the method as a simple stand-alone program, which can also be used as a plugin in existing molecular modeling software, e.g., VMD. The quality and stability of the generated structures are assessed and tested via energy scoring functions and by equilibrium MD simulations. The proposed method can also be used in template-based protein structure prediction. Work supported by the National Institutes of Health [R01 GM100701]. Computer time was provided by the University of Missouri Bioinformatics Consortium.

  16. Effects of digested onion extracts on intestinal gene expression: an interspecies comparison using different intestine models

    NARCIS (Netherlands)

    Hulst, M.M.; Meulen, van der J.; Hoekman, A.J.W.; Smits, M.A.

    2016-01-01

    Applicability of in vitro (human Caco-2 cells) and ex vivo intestine models (rat precision cut intestine slices and the pig in-situ small intestinal segment perfusion (SISP) technique) to study the effect of food compounds. In vitro digested yellow (YOd) and white onion extracts (WOd) were used as

  17. Model prodrugs for the intestinal oligopeptide transporter

    DEFF Research Database (Denmark)

    Nielsen, C U; Andersen, R; Brodin, Birger

    2001-01-01

    The human intestinal di/tri-peptide carrier, hPepT1, has been suggested as a target for increasing intestinal transport of low permeability compounds by creating prodrugs designed for the transporter. Model ester prodrugs using the stabilized dipeptides D-Glu-Ala and D-Asp-Ala as pro...... with a pH of approximately 6.0, but still release the model drug at the intercellular and blood pH of approximately 7.4. Even though benzyl alcohol is not a low molecular weight drug molecule, these results indicate that the dipeptide prodrug principle is a promising drug delivery concept. However......, the physico-chemical properties such as electronegativity, solubility, and log P of the drug molecule may also have an influence on the potential of these kinds of prodrugs. The purpose of the present study is to investigate whether the model drug electronegativity, estimated as Taft substitution parameter...

  18. Gintonin absorption in intestinal model systems

    Directory of Open Access Journals (Sweden)

    Byung-Hwan Lee

    2018-01-01

    Conclusion: The present study shows that gintonin could be absorbed in the intestine through transcellular and paracellular diffusion, and active transport. In addition, the lipid component of gintonin might play a key role in its intestinal absorption.

  19. Loop models on random maps via nested loops: the case of domain symmetry breaking and application to the Potts model

    Science.gov (United States)

    Borot, G.; Bouttier, J.; Guitter, E.

    2012-12-01

    We use the nested loop approach to investigate loop models on random planar maps where the domains delimited by the loops are given two alternating colors, which can be assigned different local weights, hence allowing for an explicit Z2 domain symmetry breaking. Each loop receives a non-local weight n, as well as a local bending energy which controls loop turns. By a standard cluster construction that we review, the Q = n2 Potts model on general random maps is mapped to a particular instance of this problem with domain-non-symmetric weights. We derive in full generality a set of coupled functional relations for a pair of generating series which encode the enumeration of loop configurations on maps with a boundary of a given color, and solve it by extending well-known complex analytic techniques. In the case where loops are fully packed, we analyze in detail the phase diagram of the model and derive exact equations for the position of its non-generic critical points. In particular, we underline that the critical Potts model on general random maps is not self-dual whenever Q ≠ 1. In a model with domain-symmetric weights, we also show the possibility of a spontaneous domain symmetry breaking driven by the bending energy. This article is part of ‘Lattice models and integrability’, a special issue of Journal of Physics A: Mathematical and Theoretical in honour of F Y Wu's 80th birthday.

  20. A Culture-Behavior-Brain Loop Model of Human Development.

    Science.gov (United States)

    Han, Shihui; Ma, Yina

    2015-11-01

    Increasing evidence suggests that cultural influences on brain activity are associated with multiple cognitive and affective processes. These findings prompt an integrative framework to account for dynamic interactions between culture, behavior, and the brain. We put forward a culture-behavior-brain (CBB) loop model of human development that proposes that culture shapes the brain by contextualizing behavior, and the brain fits and modifies culture via behavioral influences. Genes provide a fundamental basis for, and interact with, the CBB loop at both individual and population levels. The CBB loop model advances our understanding of the dynamic relationships between culture, behavior, and the brain, which are crucial for human phylogeny and ontogeny. Future brain changes due to cultural influences are discussed based on the CBB loop model. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Effects of Digested Onion Extracts on Intestinal Gene Expression: An Interspecies Comparison Using Different Intestine Models.

    Directory of Open Access Journals (Sweden)

    Nicole J W de Wit

    Full Text Available Human intestinal tissue samples are barely accessible to study potential health benefits of nutritional compounds. Numbers of animals used in animal trials, however, need to be minimalized. Therefore, we explored the applicability of in vitro (human Caco-2 cells and ex vivo intestine models (rat precision cut intestine slices and the pig in-situ small intestinal segment perfusion (SISP technique to study the effect of food compounds. In vitro digested yellow (YOd and white onion extracts (WOd were used as model food compounds and transcriptomics was applied to obtain more insight into which extent mode of actions depend on the model. The three intestine models shared 9,140 genes which were used to compare the responses to digested onions between the models. Unsupervised clustering analysis showed that genes up- or down-regulated by WOd in human Caco-2 cells and rat intestine slices were similarly regulated by YOd, indicating comparable modes of action for the two onion species. Highly variable responses to onion were found in the pig SISP model. By focussing only on genes with significant differential expression, in combination with a fold change > 1.5, 15 genes showed similar onion-induced expression in human Caco-2 cells and rat intestine slices and 2 overlapping genes were found between the human Caco-2 and pig SISP model. Pathway analyses revealed that mainly processes related to oxidative stress, and especially the Keap1-Nrf2 pathway, were affected by onions in all three models. Our data fit with previous in vivo studies showing that the beneficial effects of onions are mostly linked to their antioxidant properties. Taken together, our data indicate that each of the in vitro and ex vivo intestine models used in this study, taking into account their limitations, can be used to determine modes of action of nutritional compounds and can thereby reduce the number of animals used in conventional nutritional intervention studies.

  2. Effects of Digested Onion Extracts on Intestinal Gene Expression: An Interspecies Comparison Using Different Intestine Models.

    Science.gov (United States)

    de Wit, Nicole J W; Hulst, Marcel; Govers, Coen; van der Meulen, Jan; van Hoef, Angeline; Stoopen, Geert; Hamers, Astrid; Hoekman, Arjan; de Vos, Ric; Bovee, Toine F H; Smits, Mari; Mes, Jurriaan J; Hendriksen, Peter J M

    2016-01-01

    Human intestinal tissue samples are barely accessible to study potential health benefits of nutritional compounds. Numbers of animals used in animal trials, however, need to be minimalized. Therefore, we explored the applicability of in vitro (human Caco-2 cells) and ex vivo intestine models (rat precision cut intestine slices and the pig in-situ small intestinal segment perfusion (SISP) technique) to study the effect of food compounds. In vitro digested yellow (YOd) and white onion extracts (WOd) were used as model food compounds and transcriptomics was applied to obtain more insight into which extent mode of actions depend on the model. The three intestine models shared 9,140 genes which were used to compare the responses to digested onions between the models. Unsupervised clustering analysis showed that genes up- or down-regulated by WOd in human Caco-2 cells and rat intestine slices were similarly regulated by YOd, indicating comparable modes of action for the two onion species. Highly variable responses to onion were found in the pig SISP model. By focussing only on genes with significant differential expression, in combination with a fold change > 1.5, 15 genes showed similar onion-induced expression in human Caco-2 cells and rat intestine slices and 2 overlapping genes were found between the human Caco-2 and pig SISP model. Pathway analyses revealed that mainly processes related to oxidative stress, and especially the Keap1-Nrf2 pathway, were affected by onions in all three models. Our data fit with previous in vivo studies showing that the beneficial effects of onions are mostly linked to their antioxidant properties. Taken together, our data indicate that each of the in vitro and ex vivo intestine models used in this study, taking into account their limitations, can be used to determine modes of action of nutritional compounds and can thereby reduce the number of animals used in conventional nutritional intervention studies.

  3. A Revised Model for Dosimetry in the Human Small Intestine

    Energy Technology Data Exchange (ETDEWEB)

    John Poston; Nasir U. Bhuiyan; R. Alex Redd; Neil Parham; Jennifer Watson

    2005-02-28

    A new model for an adult human gastrointestinal tract (GIT) has been developed for use in internal dose estimations to the wall of the GIT and to the other organs and tissues of the body from radionuclides deposited in the lumenal contents of the five sections of the GIT. These sections were the esophasgus, stomach, small intestine, upper large intestine, and the lower large intestine. The wall of each section was separated from its lumenal contents.

  4. A Revised Model for Dosimetry in the Human Small Intestine

    International Nuclear Information System (INIS)

    John Poston; Bhuiyan, Nasir U.; Redd, R. Alex; Neil Parham; Jennifer Watson

    2005-01-01

    A new model for an adult human gastrointestinal tract (GIT) has been developed for use in internal dose estimations to the wall of the GIT and to the other organs and tissues of the body from radionuclides deposited in the lumenal contents of the five sections of the GIT. These sections were the esophasgus, stomach, small intestine, upper large intestine, and the lower large intestine. The wall of each section was separated from its lumenal contents

  5. Nonlinear model predictive control for chemical looping process

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Abhinaya; Lei, Hao; Lou, Xinsheng

    2017-08-22

    A control system for optimizing a chemical looping ("CL") plant includes a reduced order mathematical model ("ROM") that is designed by eliminating mathematical terms that have minimal effect on the outcome. A non-linear optimizer provides various inputs to the ROM and monitors the outputs to determine the optimum inputs that are then provided to the CL plant. An estimator estimates the values of various internal state variables of the CL plant. The system has one structure adapted to control a CL plant that only provides pressure measurements in the CL loops A and B, a second structure adapted to a CL plant that provides pressure measurements and solid levels in both loops A, and B, and a third structure adapted to control a CL plant that provides full information on internal state variables. A final structure provides a neural network NMPC controller to control operation of loops A and B.

  6. One-loop effective potential from compactified superstring models

    International Nuclear Information System (INIS)

    Gaillard, M.K.

    1985-10-01

    A recent determination is reported of the one loop effective potential from the effective tree Lagrangian in models obtained from compactification of the zero-slope limit of superstring theories, both with and without induced terms conjectured to arise from nonperturbative effects in a hidden sector theory. In the absence of condensate effects, the vacuum structure of the tree potential is preserved by the one-loop radiative corrections. In the presence of supersymmetry breaking condensate effects at tree level, the gauge non-singlet scalars remain massless at the one-loop level. In this case the vacuum expectation value of Re t and therefore the gravitino mass are determined at one loop. Specifically, it is found that the gravitino mass, the condensate scale, and the grand unification scale must all lie within a few orders of the Planck scale. 14 refs

  7. Loop equations for multi-cut matrix models

    International Nuclear Information System (INIS)

    Akemann, G.

    1995-03-01

    The loop equation for the complex one-matrix model with a multi-cut structure is derived and solved in the planar limit. An iterative scheme for higher genus contributions to the free energy and the multi-loop correlators is presented for the two-cut model, where explicit results are given up to and including genus two. The double-scaling limit is analyzed and the relation to the one-cut solution of the hermitian and complex one-matrix model is discussed. (orig.)

  8. One Loop Renormalization of the Littlest Higgs Model

    CERN Document Server

    Grinstein, Benjamin; Uttayarat, Patipan

    2011-01-01

    In Little Higgs models a collective symmetry prevents the Higgs from acquiring a quadratically divergent mass at one loop. This collective symmetry is broken by weakly gauged interactions. Terms, like Yukawa couplings, that display collective symmetry in the bare Lagrangian are generically renormalized into a sum of terms that do not respect the collective symmetry except possibly at one renormalization point where the couplings are related so that the symmetry is restored. We study here the one loop renormalization of a prototypical example, the Littlest Higgs Model. Some features of the renormalization of this model are novel, unfamiliar form similar chiral Lagrangian studies.

  9. Challenges in LCA modelling of multiple loops for aluminium cans

    DEFF Research Database (Denmark)

    Niero, Monia; Olsen, Stig Irving

    one of the main features of circular product systems, i.e. the need to model multiple life cycles. There are some key methodological challenges that LCA has to face in order to exploit its potential in a circular economy framework, e.g. how to model the recycling of materials in multiple loops. We...

  10. Closed loop models for analyzing engineering requirements for simulators

    Science.gov (United States)

    Baron, S.; Muralidharan, R.; Kleinman, D.

    1980-01-01

    A closed loop analytic model, incorporating a model for the human pilot, (namely, the optimal control model) that would allow certain simulation design tradeoffs to be evaluated quantitatively was developed. This model was applied to a realistic flight control problem. The resulting model is used to analyze both overall simulation effects and the effects of individual elements. The results show that, as compared to an ideal continuous simulation, the discrete simulation can result in significant performance and/or workload penalties.

  11. Precision cut intestinal slices are an appropriate ex vivo model to study NSAID-induced intestinal toxicity in rats

    NARCIS (Netherlands)

    Niu, Xiaoyu; de Graaf, Inge A. M.; van der Bij, Hendrik A.; Groothuis, Geny M. M.

    2014-01-01

    Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used therapeutic agents, however, they are associated with a high prevalence of intestinal side effects. In this investigation, rat precision cut intestinal slices (PCIS) were evaluated as an ex vivo model to study NSAID-induced intestinal

  12. One-loop Yukawa couplings in local models

    Energy Technology Data Exchange (ETDEWEB)

    Conlon, Joseph P. [Rudolf Peierls Center for Theoretical Physics, Oxford (United Kingdom); Balliol College, Oxford (United Kingdom); Goodsell, Mark [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Palti, Eran [Centre de Physique Theorique, Ecole Polytechnique, CNRS, Palaiseau (France)

    2010-07-15

    We calculate the one-loop Yukawa couplings and threshold corrections for supersymmetric local models of branes at singularities in type IIB string theory. We compute the corrections coming both from wavefunction and vertex renormalisation. The former comes in the IR from conventional field theory running and in the UV from threshold corrections that cause it to run from the winding scale associated to the full Calabi-Yau volume. The vertex correction is naively absent as it appears to correspond to superpotential renormalisation. However, we find that while the Wilsonian superpotential is not renormalised there is a physical vertex correction in the 1PI action associated to light particle loops. (orig.)

  13. One-loop Yukawa Couplings in Local Models

    CERN Document Server

    Conlon, Joseph P; Palti, Eran; 10.1007

    2010-01-01

    We calculate the one-loop Yukawa couplings and threshold corrections for supersymmetric local models of branes at singularities in type IIB string theory. We compute the corrections coming both from wavefunction and vertex renormalisation. The former comes in the IR from conventional field theory running and in the UV from threshold corrections that cause it to run from the winding scale associated to the full Calabi-Yau volume. The vertex correction is naively absent as it appears to correspond to superpotential renormalisation. However, we find that while the Wilsonian superpotential is not renormalised there is a physical vertex correction in the 1PI action associated to light particle loops.

  14. Nonplanar loops leave the Veneziano model photon massless

    NARCIS (Netherlands)

    Foda, O.

    1987-01-01

    The absence of a pole at p2=0 in the orientable nonplanar one-loop photon self-energy in the Veneziano model is verified. Thus the photon remains massless, and spontaneous symmetry breaking - at least as reported in this context in the literature - is not found.

  15. Nonplanar loops leave the Veneziano model photon massless

    International Nuclear Information System (INIS)

    Foda, O.

    1987-01-01

    The absence of a pole at p 2 =0 in the orientable nonplanar one-loop photon self-energy in the Veneziano model is verified. Thus the photon remains massless, and spontaneous symmetry breaking - at least as reported in this context in the literature - is not found. (orig.)

  16. Nonplanar loops leave the Veneziano model photon massless

    Energy Technology Data Exchange (ETDEWEB)

    Foda, O.

    1987-04-16

    The absence of a pole at p/sup 2/=0 in the orientable nonplanar one-loop photon self-energy in the Veneziano model is verified. Thus the photon remains massless, and spontaneous symmetry breaking - at least as reported in this context in the literature - is not found.

  17. A Looping-Based Model for Quenching Repression.

    Directory of Open Access Journals (Sweden)

    Yaroslav Pollak

    2017-01-01

    Full Text Available We model the regulatory role of proteins bound to looped DNA using a simulation in which dsDNA is represented as a self-avoiding chain, and proteins as spherical protrusions. We simulate long self-avoiding chains using a sequential importance sampling Monte-Carlo algorithm, and compute the probabilities for chain looping with and without a protrusion. We find that a protrusion near one of the chain's termini reduces the probability of looping, even for chains much longer than the protrusion-chain-terminus distance. This effect increases with protrusion size, and decreases with protrusion-terminus distance. The reduced probability of looping can be explained via an eclipse-like model, which provides a novel inhibitory mechanism. We test the eclipse model on two possible transcription-factor occupancy states of the D. melanogaster eve 3/7 enhancer, and show that it provides a possible explanation for the experimentally-observed eve stripe 3 and 7 expression patterns.

  18. Dimethyloxalylglycine preserves the intestinal microvasculature and protects against intestinal injury in a neonatal mouse NEC model: role of VEGF signaling.

    Science.gov (United States)

    Bowker, Rakhee M; Yan, Xiaocai; Managlia, Elizabeth; Liu, Shirley X L; Marek, Catherine; Tan, Xiao-Di; De Plaen, Isabelle G

    2018-02-01

    BackgroundNecrotizing enterocolitis (NEC) is a devastating neonatal disease characterized by intestinal necrosis. Hypoxia-inducible factor-1α (HIF-1α) has a critical role in cellular oxygen homeostasis. Here, we hypothesized that prolyl hydroxylase (PHD) inhibition, which stabilizes HIF-1α, protects against NEC by promoting intestinal endothelial cell proliferation and improving intestinal microvascular integrity via vascular endothelial growth factor (VEGF) signaling.MethodsTo assess the role of PHD inhibition in a neonatal mouse NEC model, we administered dimethyloxalylglycine (DMOG) or vehicle to pups before or during the NEC protocol, and determined mortality and incidence of severe intestinal injury. We assessed intestinal VEGF by western blot analysis and quantified endothelial cell and epithelial cell proliferation following immunofluorescence.ResultsDMOG decreased mortality and incidence of severe NEC, increased intestinal VEGF expression, and increased intestinal villus endothelial and epithelial cell proliferation in experimental NEC. Inhibiting VEGFR2 signaling eliminated DMOG's protective effect on intestinal injury severity, survival, and endothelial cell proliferation while sparing DMOG's protective effect on intestinal epithelial cell proliferation.ConclusionDMOG upregulates intestinal VEGF, promotes endothelial cell proliferation, and protects against intestinal injury and mortality in experimental NEC in a VEGFR2 dependent manner. DMOG's protective effect on the neonatal intestinal mucosa may be mediated via VEGFR2 dependent improvement of the intestinal microvasculature.

  19. A Statistical Model of Current Loops and Magnetic Monopoles

    International Nuclear Information System (INIS)

    Ayyer, Arvind

    2015-01-01

    We formulate a natural model of loops and isolated vertices for arbitrary planar graphs, which we call the monopole-dimer model. We show that the partition function of this model can be expressed as a determinant. We then extend the method of Kasteleyn and Temperley-Fisher to calculate the partition function exactly in the case of rectangular grids. This partition function turns out to be a square of a polynomial with positive integer coefficients when the grid lengths are even. Finally, we analyse this formula in the infinite volume limit and show that the local monopole density, free energy and entropy can be expressed in terms of well-known elliptic functions. Our technique is a novel determinantal formula for the partition function of a model of isolated vertices and loops for arbitrary graphs

  20. In Situ Perfusion Model in Rat Colon for Drug Absorption Studies: Comparison with Small Intestine and Caco-2 Cell Model.

    Science.gov (United States)

    Lozoya-Agullo, Isabel; González-Álvarez, Isabel; González-Álvarez, Marta; Merino-Sanjuán, Matilde; Bermejo, Marival

    2015-09-01

    Our aim is to develop and to validate the in situ closed loop perfusion method in rat colon and to compare with small intestine and Caco-2 cell models. Correlations with human oral fraction absorbed (Fa) and human colon fraction absorbed (Fa_colon) were developed to check the applicability of the rat colon model for controlled release (CR) drug screening. Sixteen model drugs were selected and their permeabilities assessed in rat small intestine and colon, and in Caco-2 monolayers. Correlations between colon/intestine/Caco-2 permeabilities versus human Fa and human Fa_colon have been explored to check model predictability and to apply a BCS approach in order to propose a cut off value for CR screening. Rat intestine perfusion with Doluisio's method and single-pass technique provided a similar range of permeabilities demonstrating the possibility of combining data from different laboratories. Rat colon permeability was well correlated with Caco-2 cell-4 days model reflecting a higher paracellular permeability. Rat colon permeabilities were also higher than human colon ones. In spite of the magnitude differences, a good sigmoidal relationship has been shown between rat colon permeabilities and human colon fractions absorbed, indicating that rat colon perfusion can be used for compound classification and screening of CR candidates. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

  1. Loop algorithms for quantum simulations of fermion models on lattices

    International Nuclear Information System (INIS)

    Kawashima, N.; Gubernatis, J.E.; Evertz, H.G.

    1994-01-01

    Two cluster algorithms, based on constructing and flipping loops, are presented for world-line quantum Monte Carlo simulations of fermions and are tested on the one-dimensional repulsive Hubbard model. We call these algorithms the loop-flip and loop-exchange algorithms. For these two algorithms and the standard world-line algorithm, we calculated the autocorrelation times for various physical quantities and found that the ordinary world-line algorithm, which uses only local moves, suffers from very long correlation times that makes not only the estimate of the error difficult but also the estimate of the average values themselves difficult. These difficulties are especially severe in the low-temperature, large-U regime. In contrast, we find that new algorithms, when used alone or in combinations with themselves and the standard algorithm, can have significantly smaller autocorrelation times, in some cases being smaller by three orders of magnitude. The new algorithms, which use nonlocal moves, are discussed from the point of view of a general prescription for developing cluster algorithms. The loop-flip algorithm is also shown to be ergodic and to belong to the grand canonical ensemble. Extensions to other models and higher dimensions are briefly discussed

  2. Conformational Sampling in Template-Free Protein Loop Structure Modeling: An Overview

    Directory of Open Access Journals (Sweden)

    Yaohang Li

    2013-02-01

    Full Text Available Accurately modeling protein loops is an important step to predict three-dimensional structures as well as to understand functions of many proteins. Because of their high flexibility, modeling the three-dimensional structures of loops is difficult and is usually treated as a “mini protein folding problem” under geometric constraints. In the past decade, there has been remarkable progress in template-free loop structure modeling due to advances of computational methods as well as stably increasing number of known structures available in PDB. This mini review provides an overview on the recent computational approaches for loop structure modeling. In particular, we focus on the approaches of sampling loop conformation space, which is a critical step to obtain high resolution models in template-free methods. We review the potential energy functions for loop modeling, loop buildup mechanisms to satisfy geometric constraints, and loop conformation sampling algorithms. The recent loop modeling results are also summarized.

  3. CONFORMATIONAL SAMPLING IN TEMPLATE-FREE PROTEIN LOOP STRUCTURE MODELING: AN OVERVIEW

    Directory of Open Access Journals (Sweden)

    Yaohang Li

    2013-02-01

    Full Text Available Accurately modeling protein loops is an important step to predict three-dimensional structures as well as to understand functions of many proteins. Because of their high flexibility, modeling the three-dimensional structures of loops is difficult and is usually treated as a “mini protein folding problem” under geometric constraints. In the past decade, there has been remarkable progress in template-free loop structure modeling due to advances of computational methods as well as stably increasing number of known structures available in PDB. This mini review provides an overview on the recent computational approaches for loop structure modeling. In particular, we focus on the approaches of sampling loop conformation space, which is a critical step to obtain high resolution models in template-free methods. We review the potential energy functions for loop modeling, loop buildup mechanisms to satisfy geometric constraints, and loop conformation sampling algorithms. The recent loop modeling results are also summarized.

  4. Conformational sampling in template-free protein loop structure modeling: an overview.

    Science.gov (United States)

    Li, Yaohang

    2013-01-01

    Accurately modeling protein loops is an important step to predict three-dimensional structures as well as to understand functions of many proteins. Because of their high flexibility, modeling the three-dimensional structures of loops is difficult and is usually treated as a "mini protein folding problem" under geometric constraints. In the past decade, there has been remarkable progress in template-free loop structure modeling due to advances of computational methods as well as stably increasing number of known structures available in PDB. This mini review provides an overview on the recent computational approaches for loop structure modeling. In particular, we focus on the approaches of sampling loop conformation space, which is a critical step to obtain high resolution models in template-free methods. We review the potential energy functions for loop modeling, loop buildup mechanisms to satisfy geometric constraints, and loop conformation sampling algorithms. The recent loop modeling results are also summarized.

  5. Driver steering model for closed-loop steering function analysis

    Science.gov (United States)

    Bolia, Pratiksh; Weiskircher, Thomas; Müller, Steffen

    2014-05-01

    In this paper, a two level preview driver steering control model for the use in numerical vehicle dynamics simulation is introduced. The proposed model is composed of cascaded control loops: The outer loop is the path following layer based on potential field framework. The inner loop tries to capture the driver's physical behaviour. The proposed driver model allows easy implementation of different driving situations to simulate a wide range of different driver types, moods and vehicle types. The expediency of the proposed driver model is shown with the help of developed driver steering assist (DSA) function integrated with a conventional series production (Electric Power steering System with rack assist servo unit) system. With the help of the DSA assist function, the driver is prevented from over saturating the front tyre forces and loss of stability and controllability during cornering. The simulation results show different driver reactions caused by the change in the parameters or properties of the proposed driver model if the DSA assist function is activated. Thus, the proposed driver model is useful for the advanced driver steering and vehicle stability assist function evaluation in the early stage of vehicle dynamics handling and stability evaluation.

  6. Transient modelling of a natural circulation loop under variable pressure

    Energy Technology Data Exchange (ETDEWEB)

    Vianna, Andre L.B.; Faccini, Jose L.H.; Su, Jian, E-mail: avianna@nuclear.ufrj.br, E-mail: sujian@nuclear.ufrj.br, E-mail: faccini@ien.gov.br [Coordenacao de Pos-Graduacao e Pesquisa de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Lab. de Termo-Hidraulica Experimental

    2017-07-01

    The objective of the present work is to model the transient operation of a natural circulation loop, which is one-tenth scale in height to a typical Passive Residual Heat Removal system (PRHR) of an Advanced Pressurized Water Nuclear Reactor and was designed to meet the single and two-phase flow similarity criteria to it. The loop consists of a core barrel with electrically heated rods, upper and lower plena interconnected by hot and cold pipe legs to a seven-tube shell heat exchanger of countercurrent design, and an expansion tank with a descending tube. A long transient characterized the loop operation, during which a phenomenon of self-pressurization, without self-regulation of the pressure, was experimentally observed. This represented a unique situation, named natural circulation under variable pressure (NCVP). The self-pressurization was originated in the air trapped in the expansion tank and compressed by the loop water dilatation, as it heated up during each experiment. The mathematical model, initially oriented to the single-phase flow, included the heat capacity of the structure and employed a cubic polynomial approximation for the density, in the buoyancy term calculation. The heater was modelled taking into account the different heat capacities of the heating elements and the heater walls. The heat exchanger was modelled considering the coolant heating, during the heat exchanging process. The self-pressurization was modelled as an isentropic compression of a perfect gas. The whole model was computationally implemented via a set of finite difference equations. The corresponding computational algorithm of solution was of the explicit, marching type, as for the time discretization, in an upwind scheme, regarding the space discretization. The computational program was implemented in MATLAB. Several experiments were carried out in the natural circulation loop, having the coolant flow rate and the heating power as control parameters. The variables used in the

  7. Lattice refining loop quantum cosmology, anisotropic models, and stability

    International Nuclear Information System (INIS)

    Bojowald, Martin; Cartin, Daniel; Khanna, Gaurav

    2007-01-01

    A general class of loop quantizations for anisotropic models is introduced and discussed, which enhances loop quantum cosmology by relevant features seen in inhomogeneous situations. The main new effect is an underlying lattice which is being refined during dynamical changes of the volume. In general, this leads to a new feature of dynamical difference equations which may not have constant step-size, posing new mathematical problems. It is discussed how such models can be evaluated and what lattice refinements imply for semiclassical behavior. Two detailed examples illustrate that stability conditions can put strong constraints on suitable refinement models, even in the absence of a fundamental Hamiltonian which defines changes of the underlying lattice. Thus, a large class of consistency tests of loop quantum gravity becomes available. In this context, it will also be seen that quantum corrections due to inverse powers of metric components in a constraint are much larger than they appeared recently in more special treatments of isotropic, free scalar models where they were artificially suppressed

  8. Effects of subtherapeutic concentrations of antimicrobials on gene acquisition events in Yersinia, Proteus, Shigella, and Salmonella recipient organisms in isolated ligated intestinal loops of swine.

    Science.gov (United States)

    Brewer, Matt T; Xiong, Nalee; Anderson, Kristi L; Carlson, Steve A

    2013-08-01

    To assess antimicrobial resistance and transfer of virulence genes facilitated by subtherapeutic concentrations of antimicrobials in swine intestines. 20 anesthetized pigs experimentally inoculated with donor and recipient bacteria. 4 recipient pathogenic bacteria (Salmonella enterica serotype Typhimurium, Yersinia enterocolitica, Shigella flexneri, or Proteus mirabilis) were incubated with donor bacteria in the presence of subinhibitory concentrations of 1 of 16 antimicrobials in isolated ligated intestinal loops in swine. Donor Escherichia coli contained transferrable antimicrobial resistance or virulence genes. After coincubations, intestinal contents were removed and assessed for pathogens that acquired new antimicrobial resistance or virulence genes following exposure to the subtherapeutic concentrations of antimicrobials. 3 antimicrobials (apramycin, lincomycin, and neomycin) enhanced transfer of an antimicrobial resistance plasmid from commensal E coli organisms to Yersinia and Proteus organisms, whereas 7 antimicrobials (florfenicol, hygromycin, penicillin G, roxarsone, sulfamethazine, tetracycline, and tylosin) exacerbated transfer of an integron (Salmonella genomic island 1) from Salmonella organisms to Yersinia organisms. Sulfamethazine induced the transfer of Salmonella pathogenicity island 1 from pathogenic to nonpathogenic Salmonella organisms. Six antimicrobials (bacitracin, carbadox, erythromycin, sulfathiazole, tiamulin, and virginiamycin) did not mediate any transfer events. Sulfamethazine was the only antimicrobial implicated in 2 types of transfer events. 10 of 16 antimicrobials at subinhibitory or subtherapeutic concentrations augmented specific antimicrobial resistance or transfer of virulence genes into pathogenic bacteria in isolated intestinal loops in swine. Use of subtherapeutic antimicrobials in animal feed may be associated with unwanted collateral effects.

  9. A LabVIEW model incorporating an open-loop arterial impedance and a closed-loop circulatory system.

    Science.gov (United States)

    Cole, R T; Lucas, C L; Cascio, W E; Johnson, T A

    2005-11-01

    While numerous computer models exist for the circulatory system, many are limited in scope, contain unwanted features or incorporate complex components specific to unique experimental situations. Our purpose was to develop a basic, yet multifaceted, computer model of the left heart and systemic circulation in LabVIEW having universal appeal without sacrificing crucial physiologic features. The program we developed employs Windkessel-type impedance models in several open-loop configurations and a closed-loop model coupling a lumped impedance and ventricular pressure source. The open-loop impedance models demonstrate afterload effects on arbitrary aortic pressure/flow inputs. The closed-loop model catalogs the major circulatory waveforms with changes in afterload, preload, and left heart properties. Our model provides an avenue for expanding the use of the ventricular equations through closed-loop coupling that includes a basic coronary circuit. Tested values used for the afterload components and the effects of afterload parameter changes on various waveforms are consistent with published data. We conclude that this model offers the ability to alter several circulatory factors and digitally catalog the most salient features of the pressure/flow waveforms employing a user-friendly platform. These features make the model a useful instructional tool for students as well as a simple experimental tool for cardiovascular research.

  10. Higher Rank ABJM Wilson Loops from Matrix Models

    Science.gov (United States)

    Cookmeyer, Jonathan; Liu, James; Zayas, Leopoldo

    2017-01-01

    We compute the expectation values of 1/6 supersymmetric Wilson Loops in ABJM theory in higher rank representations. Using standard matrix model techniques, we calculate the expectation value in the rank m fully symmetric and fully antisymmetric representation where m is scaled with N. To leading order, we find agreement with the classical action of D6 and D2 branes in AdS4 ×CP3 respectively. Further, we compute the first subleading order term, which, on the AdS side, makes a prediction for the one-loop effective action of the corresponding D6 and D2 branes. Supported by the National Science Foundation under Grant No. PHY 1559988 and the US Department of Energy under Grant No. DE-SC0007859.

  11. Blind Loop Syndrome

    Science.gov (United States)

    ... of tissue that protrude through the intestinal wall (diverticulosis) Certain medical conditions, including Crohn's disease, radiation enteritis, ... History of radiation therapy to the abdomen Diabetes Diverticulosis of the small intestine Complications A blind loop ...

  12. Digestion modeling in the small intestine: impact of dietary fiber.

    Science.gov (United States)

    Taghipoor, M; Barles, G; Georgelin, C; Licois, J R; Lescoat, P

    2014-12-01

    In this work, the modeling of the digestion in the small intestine is developed by investigating specifically the effects of dietary fiber. As our previous model, this new version takes into account the three main phenomena of digestion: transit of the bolus, degradation of feedstuffs and absorption through the intestinal wall. However the two main physiochemical characteristics of dietary fiber, namely viscosity and water holding capacity, lead us to substantially modify our initial model by emphasizing the role of water and its intricated dynamics with dry matter in the bolus. Various numerical simulations given by this new model are qualitatively in agreement with the positive effect of insoluble dietary fiber on the velocity of bolus and on its degradation all along the small intestine. These simulations reproduce the negative effect of soluble dietary fiber on digestion as it has been experimentally observed. Although, this model is generic and contains a large number of parameters but, to the best of our knowledge, it is among the first qualitative dynamical models of fiber influence on intestinal digestion. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Higher rank ABJM Wilson loops from matrix models

    Energy Technology Data Exchange (ETDEWEB)

    Cookmeyer, Jonathan [Haverford College,370 Lancaster Avenue, Haverford, PA, 19041 (United States); Liu, James T. [Michigan Center for Theoretical Physics, Department of Physics, University of Michigan,450 Church Street, Ann Arbor, MI, 48109 (United States); Zayas, Leopoldo A. Pando [The Abdus Salam International Centre for Theoretical Physics,Strada Costiera 11, Trieste, 34014 (Italy)

    2016-11-21

    We compute the vacuum expectation values of 1/6 supersymmetric Wilson loops in higher dimensional representations of the gauge group in ABJM theory. We present results for the m-symmetric and m-antisymmetric representations by exploiting standard matrix model techniques. At leading order, in the saddle point approximation, our expressions reproduce holographic results from both D6 and D2 branes corresponding to the antisymmetric and symmetric representations, respectively. We also compute 1/N corrections to the leading saddle point results.

  14. [Intestinal lengthening techniques: an experimental model in dogs].

    Science.gov (United States)

    Garibay González, Francisco; Díaz Martínez, Daniel Alberto; Valencia Flores, Alejandro; González Hernández, Miguel Angel

    2005-01-01

    To compare two intestinal lengthening procedures in an experimental dog model. Intestinal lengthening is one of the methods for gastrointestinal reconstruction used for treatment of short bowel syndrome. The modification to the Bianchi's technique is an alternative. The modified technique decreases the number of anastomoses to a single one, thus reducing the risk of leaks and strictures. To our knowledge there is not any clinical or experimental report that studied both techniques, so we realized the present report. Twelve creole dogs were operated with the Bianchi technique for intestinal lengthening (group A) and other 12 creole dogs from the same race and weight were operated by the modified technique (Group B). Both groups were compared in relation to operating time, difficulties in technique, cost, intestinal lengthening and anastomoses diameter. There were no statistical difference in the anastomoses diameter (A = 9.0 mm vs. B = 8.5 mm, p = 0.3846). Operating time (142 min vs. 63 min) cost and technique difficulties were lower in group B (p anastomoses (of Group B) and intestinal segments had good blood supply and were patent along their full length. Bianchi technique and the modified technique offer two good reliable alternatives for the treatment of short bowel syndrome. The modified technique improved operating time, cost and technical issues.

  15. Finding Positive Feedback Loops in Environmental Models: A Mathematical Investigation

    Science.gov (United States)

    Sheikholeslami, R.; Razavi, S.

    2016-12-01

    Dynamics of most earth and environmental systems are generally governed by interactions between several hydrological (e.g., soil moisture and precipitation), geological (e.g., and erosion), geochemical (e.g., nutrient loading), and atmospheric (e.g., temperature) processes which operate on a range of spatio-temporal scales. These interactions create numerous feedback mechanisms with complex behaviours, and their understanding and representation can vary depending on the scale in space and/or time at which the system is analyzed. One of the most crucial characteristics of such complex systems is the existence of positive feedback loops. The presence of positive feedbacks may increase complexity, accelerate change, or trigger multiple stable states in the underlying dynamical system. Furthermore, because of the inherent non-linearity, it is often very difficult to obtain a general idea of their complex dynamics. Feedback loops in environmental systems have been well recognized and qualitatively discussed. With a quantitative/mathematical view, in this presentation, we address the question of how the positive feedback loops can be identified/implemented in environmental models. We investigate the nature of different feedback mechanisms and dynamics of simple example case studies that underlie fundamental processes such as vegetation, precipitation and soil moisture. To do this, we apply the concept of "interaction graph" from mathematics which is built from the Jacobian matrix of the dynamical system. The Jacobian matrix contains information on how variations of one state variable depends on variations of other variables, and thus can be used to understand the dynamical possibilities of feedback mechanisms in the underlying system. Moreover, this study highlights that there are some situations where the existence of positive feedback loops can cause multiple stable states, and thereby regime shifts in environmental systems. Systems with multiple stable states are

  16. Modeling Loop Reorganization Free Energies of Acetylcholinesterase: A Comparison of Explicit and Implicit Solvent Models

    National Research Council Canada - National Science Library

    Olson, Mark

    2004-01-01

    ... screening of charge-charge interactions. This paper compares different solvent models applied to the problem of estimating the free-energy difference between two loop conformations in acetylcholinesterase...

  17. Repeated mechanical lengthening of intestinal segments in a novel model.

    Science.gov (United States)

    Scott, Andrew; Sullins, Veronica F; Steinberger, Doug; Rouch, Joshua D; Wagner, Justin P; Chiang, Elvin; Lee, Steven L; Wu, Benjamin M; Dunn, James C Y

    2015-06-01

    Currently, animal models used for mechanical intestinal lengthening utilize a single lengthening procedure prior to analysis or restoration back into continuity. Here we developed a novel surgical model to examine the feasibility of repeated lengthening of intestinal segments. A Roux-en-Y jejunojejunostomy with a blind Roux limb was created in rats. An encapsulated polycaprolactone spring was placed into a 1cm segment of the Roux limb. After 4 weeks, a second encapsulated PCL spring was inserted into a 1cm portion of the lengthened segment. After another 4 weeks, the repeatedly lengthened segments were retrieved for histological analyses. Jejunal segments of the Roux limb were successfully lengthened from 1.0 cm to 2.6 ± 0.7 cm. Four weeks after the second PCL spring placement, 1.0 cm of the previously lengthened segment increased to 2.7 ± 0.8 cm. Stronger mechanical force was required to achieve subsequent re-lengthening. Lengthened and re-lengthened segments had increased smooth muscle thickness and crypt depth when compared to normal jejunal mucosa. Using the Roux-en-Y model, previously lengthened segments of intestine can be successfully re-lengthened. Intestinal segments may be subjected to multiple lengthening procedures to achieve clinically significant length for the treatment of short bowel syndrome. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. Efficient dynamic modeling of manipulators containing closed kinematic loops

    Science.gov (United States)

    Ferretti, Gianni; Rocco, Paolo

    An approach to efficiently solve the forward dynamics problem for manipulators containing closed chains is proposed. The two main distinctive features of this approach are: the dynamics of the equivalent open loop tree structures (any closed loop can be in general modeled by imposing some additional kinematic constraints to a suitable tree structure) is computed through an efficient Newton Euler formulation; the constraint equations relative to the most commonly adopted closed chains in industrial manipulators are explicitly solved, thus, overcoming the redundancy of Lagrange's multipliers method while avoiding the inefficiency due to a numerical solution of the implicit constraint equations. The constraint equations considered for an explicit solution are those imposed by articulated gear mechanisms and planar closed chains (pantograph type structures). Articulated gear mechanisms are actually used in all industrial robots to transmit motion from actuators to links, while planar closed chains are usefully employed to increase the stiffness of the manipulators and their load capacity, as well to reduce the kinematic coupling of joint axes. The accuracy and the efficiency of the proposed approach are shown through a simulation test.

  19. Flare parameters inferred from a 3D loop model database

    Science.gov (United States)

    Cuambe, Valente A.; Costa, J. E. R.; Simões, P. J. A.

    2018-04-01

    We developed a database of pre-calculated flare images and spectra exploring a set of parameters which describe the physical characteristics of coronal loops and accelerated electron distribution. Due to the large number of parameters involved in describing the geometry and the flaring atmosphere in the model used (Costa et al. 2013), we built a large database of models (˜250 000) to facilitate the flare analysis. The geometry and characteristics of non-thermal electrons are defined on a discrete grid with spatial resolution greater than 4 arcsec. The database was constructed based on general properties of known solar flares and convolved with instrumental resolution to replicate the observations from the Nobeyama radio polarimeter (NoRP) spectra and Nobeyama radio-heliograph (NoRH) brightness maps. Observed spectra and brightness distribution maps are easily compared with the modelled spectra and images in the database, indicating a possible range of solutions. The parameter search efficiency in this finite database is discussed. Eight out of ten parameters analysed for one thousand simulated flare searches were recovered with a relative error of less than 20 per cent on average. In addition, from the analysis of the observed correlation between NoRH flare sizes and intensities at 17 GHz, some statistical properties were derived. From these statistics the energy spectral index was found to be δ ˜ 3, with non-thermal electron densities showing a peak distribution ⪅107 cm-3, and Bphotosphere ⪆2000 G. Some bias for larger loops with heights as great as ˜2.6 × 109 cm, and looptop events were noted. An excellent match of the spectrum and the brightness distribution at 17 and 34 GHz of the 2002 May 31 flare, is presented as well.

  20. The relevance of free fluid between intestinal loops detected by sonography in the clinical assessment of small bowel obstruction in adults

    International Nuclear Information System (INIS)

    Grassi, Roberto; Romano, Stefania; D'Amario, Fenesia; Giorgio Rossi, Antonio; Romano, Luigia; Pinto, Fabio; Di Mizio, Roberto

    2004-01-01

    Introduction: The main role of the radiologist in the management of patients with suspicion of small bowel obstruction is to help triage patients into those that need immediate surgical intervention from those that require medical therapy or delayed surgery. Ultrasound examination is usually considered not helpful in bowel obstruction because of air in the intestinal lumen that interferes the evaluation of the intestinal loops, however recently some Authors attested the increasing important role of sonography in the acute abdominal disease. Aim of our report is to demonstrate the value of free fluid detected by US in differentiating between low and high-grade small bowel obstruction. Materials and methods: The study is based on 742 consecutive patients who presented symptoms of the acute abdomen; all patients had undergone initial serial abdominal plain film and US examinations prior to any medical intervention. We reviewed the imaging findings of 150 cases in whom small bowel obstruction was clinically suspected and confirmed at surgery. We consider the following radiographic and US findings: dilatation of small bowel loops; bowel wall thickness; presence of air-fluid levels; thickness of valvulae conniventes; evidence of peristalsis; presence and echogenicity of extraluminal fluid. We looked at the value of extraluminal peritoneal fluid at US examination in differentiating low and high-grade small bowel obstruction based on the surgical outcome. Results: In 46 patients altered peristaltic activity, thin bowel walls, fluid filled loops with hyperechoic spots in the bowel segment proximal to obstruction were noted at US, whereas radiographic features were: moderate dilatation of small bowel loops, with thin bowel wall and evidence of numerous and subtle valvulae conniventes; presence of air-fluid levels was also noted. In 70 other patients, US examination revealed all the findings described in the precedent cases and also the presence of free extraluminal fluid

  1. The relevance of free fluid between intestinal loops detected by sonography in the clinical assessment of small bowel obstruction in adults

    Energy Technology Data Exchange (ETDEWEB)

    Grassi, Roberto; Romano, Stefania E-mail: stefromano@libero.it; D' Amario, Fenesia; Giorgio Rossi, Antonio; Romano, Luigia; Pinto, Fabio; Di Mizio, Roberto

    2004-04-01

    Introduction: The main role of the radiologist in the management of patients with suspicion of small bowel obstruction is to help triage patients into those that need immediate surgical intervention from those that require medical therapy or delayed surgery. Ultrasound examination is usually considered not helpful in bowel obstruction because of air in the intestinal lumen that interferes the evaluation of the intestinal loops, however recently some Authors attested the increasing important role of sonography in the acute abdominal disease. Aim of our report is to demonstrate the value of free fluid detected by US in differentiating between low and high-grade small bowel obstruction. Materials and methods: The study is based on 742 consecutive patients who presented symptoms of the acute abdomen; all patients had undergone initial serial abdominal plain film and US examinations prior to any medical intervention. We reviewed the imaging findings of 150 cases in whom small bowel obstruction was clinically suspected and confirmed at surgery. We consider the following radiographic and US findings: dilatation of small bowel loops; bowel wall thickness; presence of air-fluid levels; thickness of valvulae conniventes; evidence of peristalsis; presence and echogenicity of extraluminal fluid. We looked at the value of extraluminal peritoneal fluid at US examination in differentiating low and high-grade small bowel obstruction based on the surgical outcome. Results: In 46 patients altered peristaltic activity, thin bowel walls, fluid filled loops with hyperechoic spots in the bowel segment proximal to obstruction were noted at US, whereas radiographic features were: moderate dilatation of small bowel loops, with thin bowel wall and evidence of numerous and subtle valvulae conniventes; presence of air-fluid levels was also noted. In 70 other patients, US examination revealed all the findings described in the precedent cases and also the presence of free extraluminal fluid

  2. Maternal administration of cannabidiol promotes an anti-inflammatory effect on the intestinal wall in a gastroschisis rat model

    Directory of Open Access Journals (Sweden)

    G.H. Callejas

    2018-03-01

    Full Text Available Gastroschisis (GS is an abdominal wall defect that results in histological and morphological changes leading to intestinal motility perturbation and impaired absorption of nutrients. Due to its anti-inflammatory, antioxidant, and neuroprotective effects, cannabidiol (CBD has been used as a therapeutic agent in many diseases. Our aim was to test the effect of maternal CBD in the intestine of an experimental model of GS. Pregnant rats were treated over 3 days with CBD (30 mg/kg after the surgical induction of GS (day 18.5 of gestation and compared to controls. Fetuses were divided into 4 groups: 1 control (C; 2 C+CBD (CCBD; 3 gastroschisis (G, and 4 G+CBD (GCBD. On day 21.5 of gestation, the fetuses were harvested and evaluated for: a body weight (BW, intestinal weight (IW, and IW/BW ratio; b histometric analysis of the intestinal wall; c immunohistochemically analysis of inflammation (iNOS and nitrite/nitrate level. BW: GCBD was lower than CCBD (P<0.005, IW and IW/BW ratio: GCBD was smaller than G (P<0.005, GCBD presented lower thickness in all parameters compared to G (P<0.005, iNOS and nitrite/nitrate were lower concentration in GCBD than to G (P<0.005. Maternal use of CBD had a beneficial effect on the intestinal loops of GS with decreased nitrite/nitrate and iNOS expression.

  3. Remarks on meson loop effects on quark models

    Energy Technology Data Exchange (ETDEWEB)

    Hammer, I.K.; Hanhart, C. [Institut fuer Kernphysik and Juelich Center for Hadron Physics, Forschungszentrum Juelich, Institute for Advanced Simulation, Juelich (Germany); Nefediev, A.V. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); National Research Nuclear University MEPhI, Moscow (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region (Russian Federation)

    2016-11-15

    We investigate the effect of meson loops on the spectrum of quark states. We demonstrate that in general quark states do not tend to get very broad if their coupling to the continuum increases, but instead they decouple from the latter in the large coupling limit. We ascribe this effect to the essentially nonperturbative unitarization procedure involved. In the meantime, some quark resonances behave very differently and demonstrate collectivity in the sense that their pole trajectories span a wide, as compared to the level spacing, region therefore acquiring contributions from multiple bare poles rather than from the closest neighbors. While the actual calculations are done within particular, very simplified models, it is argued that the findings might well be general. (orig.)

  4. Human Enteroids as a Model of Upper Small Intestinal Ion Transport Physiology and Pathophysiology

    NARCIS (Netherlands)

    J. Foulke-Abel (Jennifer); J. In (Julie); Yin, J. (Jianyi); N.C. Zachos (Nicholas C.); O. Kovbasnjuk (Olga); M.K. Estes (Mary K.); H.R. de Jonge (Hugo); M. Donowitz (Mark)

    2016-01-01

    textabstractBackground & Aims Human intestinal crypt-derived enteroids are a model of intestinal ion transport that require validation by comparison with cell culture and animal models. We used human small intestinal enteroids to study neutral Na+ absorption and stimulated fluid and anion secretion

  5. Structural Design of Oligopeptides for Intestinal Transport Model.

    Science.gov (United States)

    Hong, Seong-Min; Tanaka, Mitsuru; Koyanagi, Riho; Shen, Weilin; Matsui, Toshiro

    2016-03-16

    Glycyl-sarcosine (Gly-Sar) is a well-known model substrate for the intestinal uptake of dipeptides through peptide transporter 1 (PepT1). However, there are no other model peptides larger than tripeptides to evaluate their intestinal transport ability. In this study, we designed new oligopeptides based on the Gly-Sar structure in terms of protease resistance. Gly-Sar-Sar was found to be an appropriate transport model for tripeptides because it does not degrade during the transport across the rat intestinal membrane, while Gly-Gly-Sar was degraded to Gly-Sar during the 60 min transport. Caco-2 cell transport experiments revealed that the designed oligopeptides based on Gly-Sar-Sar showed a significantly (p transport ability by factors of 1/10-, 1/25-, and 1/40-fold for Gly-Sar-Sar, Gly-Sar-Sar-Sar, and Gly-Sar-Sar-Sar-Sar, respectively, compared to Gly-Sar (apparent permeability coefficient: 38.6 ± 11.4 cm/s). Cell experiments also showed that the designed tripeptide and Gly-Sar were transported across Caco-2 cell via PepT1, whereas the tetra- and pentapeptides were transported through the paracellular tight-junction pathway.

  6. Loop Corrections in Very Special Relativity Standard Model

    Science.gov (United States)

    Alfaro, Jorge

    2018-01-01

    In this talk we want to study one-loop corrections in VSRSM. In particular, we use the new Sim(2)-invariant dimensional regularization to compute one-loop corrections to the Effective Action in the subsector of the VSRSM that describe the interaction of photons with charged leptons. New stringent bounds for the masses of ve and vµ are obtained.

  7. Loop quantum cosmology of k=1 FRW models

    International Nuclear Information System (INIS)

    Ashtekar, Abhay; Pawlowski, Tomasz; Singh, Parampreet; Vandersloot, Kevin

    2007-01-01

    The closed, k=1, FRW model coupled to a massless scalar field is investigated in the framework of loop quantum cosmology using analytical and numerical methods. As in the k=0 case, the scalar field can be again used as emergent time to construct the physical Hilbert space and introduce Dirac observables. The resulting framework is then used to address a major challenge of quantum cosmology: resolving the big-bang singularity while retaining agreement with general relativity at large scales. It is shown that the framework fulfills this task. In particular, for states which are semiclassical at some late time, the big bang is replaced by a quantum bounce and a recollapse occurs at the value of the scale factor predicted by classical general relativity. Thus, the ''difficulties'' pointed out by Green and Unruh in the k=1 case do not arise in a more systematic treatment. As in k=0 models, quantum dynamics is deterministic across the deep Planck regime. However, because it also retains the classical recollapse, in contrast to the k=0 case one is now led to a cyclic model. Finally, we clarify some issues raised by Laguna's recent work addressed to computational physicists

  8. Protein Structure Classification and Loop Modeling Using Multiple Ramachandran Distributions

    KAUST Repository

    Najibi, Seyed Morteza

    2017-02-08

    Recently, the study of protein structures using angular representations has attracted much attention among structural biologists. The main challenge is how to efficiently model the continuous conformational space of the protein structures based on the differences and similarities between different Ramachandran plots. Despite the presence of statistical methods for modeling angular data of proteins, there is still a substantial need for more sophisticated and faster statistical tools to model the large-scale circular datasets. To address this need, we have developed a nonparametric method for collective estimation of multiple bivariate density functions for a collection of populations of protein backbone angles. The proposed method takes into account the circular nature of the angular data using trigonometric spline which is more efficient compared to existing methods. This collective density estimation approach is widely applicable when there is a need to estimate multiple density functions from different populations with common features. Moreover, the coefficients of adaptive basis expansion for the fitted densities provide a low-dimensional representation that is useful for visualization, clustering, and classification of the densities. The proposed method provides a novel and unique perspective to two important and challenging problems in protein structure research: structure-based protein classification and angular-sampling-based protein loop structure prediction.

  9. Closed-Loop Supply Chain Planning Model of Rare Metals

    Directory of Open Access Journals (Sweden)

    Dongmin Son

    2018-04-01

    Full Text Available Rare metals (RMs are becoming increasingly important in high-tech industries associated with the Fourth Industrial Revolution, such as the electric vehicle (EV and 3D printer industries. As the growth of these industries accelerates in the near future, manufacturers will also face greater RM supply risks. For this reason, many countries are putting considerable effort into securing the RM supply. For example, countries including Japan, Korea, and the USA have adopted two major policies: the stockpile system and Extended Producer Responsibility (EPR. Therefore, it is necessary for the manufacturers with RMs to establish a suitable supply chain plan that reflects this situation. In this study, the RM classification matrix is created based on the stockpile and recycling level in Korea. Accordingly, three different types of supply chain are designed in order to develop the closed-loop supply chain (CLSC planning model of RM, and the CLSC planning models of RM are validated through experimental analysis. The results show that the stockpiling and the EPR recycling obligation increase the amount of recycled flow and reduce the total cost of the part manufacturing, which means that these two factors are significant for obtaining sustainability of the RMs’ CLSC. In addition, the government needs to set an appropriate sharing cost for promoting the manufacturer’s recycling. Also, from the manufacturer’s perspective, it is better to increase the return rate by making a contract with the collectors to guarantee the collection of used products.

  10. Extending two Higgs doublet models for two-loop neutrino mass generation and one-loop neutrinoless double beta decay

    Directory of Open Access Journals (Sweden)

    Zhen Liu

    2017-02-01

    Full Text Available We extend some two Higgs doublet models, where the Yukawa couplings for the charged fermion mass generation only involve one Higgs doublet, by two singlet scalars respectively carrying a singly electric charge and a doubly electric charge. The doublet and singlet scalars together can mediate a two-loop diagram to generate a tiny Majorana mass matrix of the standard model neutrinos. Remarkably, the structure of the neutrino mass matrix is fully determined by the symmetric Yukawa couplings of the doubly charged scalar to the right-handed leptons. Meanwhile, a one-loop induced neutrinoless double beta decay can arrive at a testable level even if the electron neutrino has an extremely small Majorana mass. We also study other experimental constraints and implications including some rare processes and Higgs phenomenology.

  11. Mechanical Elongation of the Small Intestine: Evaluation of Techniques for Optimal Screw Placement in a Rodent Model

    Directory of Open Access Journals (Sweden)

    P. A. Hausbrandt

    2013-01-01

    Full Text Available Introduction. The aim of this study was to evaluate techniques and establish an optimal method for mechanical elongation of small intestine (MESI using screws in a rodent model in order to develop a potential therapy for short bowel syndrome (SBS. Material and Methods. Adult female Sprague Dawley rats (n=24 with body weight from 250 to 300 g (Σ=283 were evaluated using 5 different groups in which the basic denominator for the technique involved the fixation of a blind loop of the intestine on the abdominal wall with the placement of a screw in the lumen secured to the abdominal wall. Results. In all groups with accessible screws, the rodents removed the implants despite the use of washers or suits to prevent removal. Subcutaneous placement of the screw combined with antibiotic treatment and dietary modifications was finally successful. In two animals autologous transplantation of the lengthened intestinal segment was successful. Discussion. While the rodent model may provide useful basic information on mechanical intestinal lengthening, further investigations should be performed in larger animals to make use of the translational nature of MESI in human SBS treatment.

  12. A Mathematical Model of the Human Small Intestine Following Acute Radiation and Burn Exposures

    Science.gov (United States)

    2016-08-01

    intestinal lumen Cell Migration Radiation damages proliferating crypt cells, causing mitotic arrest and delaying regeneration Burns can...04-08-2016 Technical Report A Mathematical Model of the Human Small Intestine Following Acute Radiation and Burn Exposures HDTRA1...the small intestine , reducing the density of the gut barrier. A reduced epithelial lining can result in suppressed nutrient absorption, bacterial

  13. A Moral Experience Feedback Loop: Modeling a System of Moral Self-Cultivation in Everyday Life

    Science.gov (United States)

    Sherblom, Stephen A.

    2015-01-01

    This "systems thinking" model illustrates a common feedback loop by which people engage the moral world and continually reshape their moral sensibility. The model highlights seven processes that collectively form this feedback loop: beginning with (1) one's current moral sensibility which shapes processes of (2) perception, (3)…

  14. On equivalent radius of curvature for PWL geometrical modeling a loop antenna

    CSIR Research Space (South Africa)

    Lysko, AA

    2012-11-01

    Full Text Available A circular loop antenna is often numerically modeled using a regular polygon. This approach is simple and robust, yet it alters the circumference of the loop and may thus shift the resonance frequency in the numerical model. This letter introduces a...

  15. Bacterial translocation and intestinal injury in experimental necrotizing enterocolitis model.

    Science.gov (United States)

    Ciftci, I; Ozdemir, M; Aktan, M; Aslan, K

    2012-01-01

    To study the occurrence of bacterial translocation and to assess the impact of breastfeeding on bacterial translocation in the animal model of necrotizing enterocolitis. A total of 20 neonate Sprague-Dawley rats were enrolled in the study. Rats were randomly allocated into either control or study group just after birth. Ten newborn rats in the control group were left with their mother to be breast-fed. In contrary, necrotizing enterocolitis group consisted of neonates that were separated from their mothers, housed in an incubator and were gavaged with a special rodent formula three times daily. Survival rates, weight changes, and morphologic scoring obtained after microscopic evaluation were determined as microbiologic evaluation criteria. All the rats in the control group survived, while 1 (10 %) rat died in the necrotizing enterocolitis group. Mortality rates of the two groups were similar. All the formula-fed animals in the necrotizing enterocolitis group had significant weight loss compared to the breast milk-fed rats in the control group (pmicrorganisms in the bowel pass through the intestinal barrier and reach the liver and the spleen via the hematogenous route. This condition is closely related to the impairment of physiological and functional features of the intestinal barrier and is independent from the degree of intestinal injury. Bacterial translocation should be remembered in cases suspected of necrotizing enterocolitis, and a rapid and effective treatment algorithm should be applied in such circumstances (Tab. 3, Fig. 3, Ref. 21). Full Text in PDF www.elis.sk.

  16. Computational approaches for modeling human intestinal absorption and permeability.

    Science.gov (United States)

    Subramanian, Govindan; Kitchen, Douglas B

    2006-07-01

    Human intestinal absorption (HIA) is an important roadblock in the formulation of new drug substances. Computational models are needed for the rapid estimation of this property. The measurements are determined via in vivo experiments or in vitro permeability studies. We present several computational models that are able to predict the absorption of drugs by the human intestine and the permeability through human Caco-2 cells. The training and prediction sets were derived from literature sources and carefully examined to eliminate compounds that are actively transported. We compare our results to models derived by other methods and find that the statistical quality is similar. We believe that models derived from both sources of experimental data would provide greater consistency in predictions. The performance of several QSPR models that we investigated to predict outside the training set for either experimental property clearly indicates that caution should be exercised while applying any of the models for quantitative predictions. However, we are able to show that the qualitative predictions can be obtained with close to a 70% success rate.

  17. Cognitive Modeling for Closed-Loop Task Mitigation, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Intelligent Automation, Inc. (IAI) along with collaborators at the University of Iowa and Old Dominion University (ODU) developed an advanced closed-loop Adaptive...

  18. New class of two-loop neutrino mass models with distinguishable phenomenology

    Science.gov (United States)

    Cao, Qing-Hong; Chen, Shao-Long; Ma, Ernest; Yan, Bin; Zhang, Dong-Ming

    2018-04-01

    We discuss a new class of neutrino mass models generated in two loops, and explore specifically three new physics scenarios: (A) doubly charged scalar, (B) dark matter, and (C) leptoquark and diquark, which are verifiable at the 14 TeV LHC Run-II. We point out how the different Higgs insertions will distinguish our two-loop topology with others if the new particles in the loop are in the simplest representations of the SM gauge group.

  19. Time evolution in deparametrized models of loop quantum gravity

    Science.gov (United States)

    Assanioussi, Mehdi; Lewandowski, Jerzy; Mäkinen, Ilkka

    2017-07-01

    An important aspect in understanding the dynamics in the context of deparametrized models of loop quantum gravity (LQG) is to obtain a sufficient control on the quantum evolution generated by a given Hamiltonian operator. More specifically, we need to be able to compute the evolution of relevant physical states and observables with a relatively good precision. In this article, we introduce an approximation method to deal with the physical Hamiltonian operators in deparametrized LQG models, and we apply it to models in which a free Klein-Gordon scalar field or a nonrotational dust field is taken as the physical time variable. This method is based on using standard time-independent perturbation theory of quantum mechanics to define a perturbative expansion of the Hamiltonian operator, the small perturbation parameter being determined by the Barbero-Immirzi parameter β . This method allows us to define an approximate spectral decomposition of the Hamiltonian operators and hence to compute the evolution over a certain time interval. As a specific example, we analyze the evolution of expectation values of the volume and curvature operators starting with certain physical initial states, using both the perturbative method and a straightforward expansion of the expectation value in powers of the time variable. This work represents a first step toward achieving the goal of understanding and controlling the new dynamics developed in Alesci et al. [Phys. Rev. D 91, 124067 (2015), 10.1103/PhysRevD.91.124067] and Assanioussi et al. [Phys. Rev. D 92, 044042 (2015), 10.1103/PhysRevD.92.044042].

  20. Quantitative prediction of intestinal metabolism in humans from a simplified intestinal availability model and empirical scaling factor.

    Science.gov (United States)

    Kadono, Keitaro; Akabane, Takafumi; Tabata, Kenji; Gato, Katsuhiko; Terashita, Shigeyuki; Teramura, Toshio

    2010-07-01

    This study aimed to establish a practical and convenient method of predicting intestinal availability (F(g)) in humans for highly permeable compounds at the drug discovery stage, with a focus on CYP3A4-mediated metabolism. We constructed a "simplified F(g) model," described using only metabolic parameters, assuming that passive diffusion is dominant when permeability is high and that the effect of transporters in epithelial cells is negligible. Five substrates for CYP3A4 (alprazolam, amlodipine, clonazepam, midazolam, and nifedipine) and four for both CYP3A4 and P-glycoprotein (P-gp) (nicardipine, quinidine, tacrolimus, and verapamil) were used as model compounds. Observed fraction of drug absorbed (F(a)F(g)) values for these compounds were calculated from in vivo pharmacokinetic (PK) parameters, whereas in vitro intestinal intrinsic clearance (CL(int,intestine)) was determined using human intestinal microsomes. The CL(int,intestine) for the model compounds corrected with that of midazolam was defined as CL(m,index) and incorporated into a simplified F(g) model with empirical scaling factor. Regardless of whether the compound was a P-gp substrate, the F(a)F(g) could be reasonably fitted by the simplified F(g) model, and the value of the empirical scaling factor was well estimated. These results suggest that the effects of P-gp on F(a) and F(g) are substantially minor, at least in the case of highly permeable compounds. Furthermore, liver intrinsic clearance (CL(int,liver)) can be used as a surrogate index of intestinal metabolism based on the relationship between CL(int,liver) and CL(m,index). F(g) can be easily predicted using a simplified F(g) model with the empirical scaling factor, enabling more confident selection of drug candidates with desirable PK profiles in humans.

  1. Droop Control with an Adjustable Complex Virtual Impedance Loop based on Cloud Model Theory

    DEFF Research Database (Denmark)

    Li, Yan; Shuai, Zhikang; Xu, Qinming

    2016-01-01

    Droop control framework with an adjustable virtual impedance loop is proposed in this paper, which is based on the cloud model theory. The proposed virtual impedance loop includes two terms: a negative virtual resistor and an adjustable virtual inductance. The negative virtual resistor term...

  2. Computational Model of a Positive BDNF Feedback Loop in Hippocampal Neurons Following Inhibitory Avoidance Training

    Science.gov (United States)

    Zhang, Yili; Smolen, Paul; Alberini, Cristina M.; Baxter, Douglas A.; Byrne, John H.

    2016-01-01

    Inhibitory avoidance (IA) training in rodents initiates a molecular cascade within hippocampal neurons. This cascade contributes to the transition of short- to long-term memory (i.e., consolidation). Here, a differential equation-based model was developed to describe a positive feedback loop within this molecular cascade. The feedback loop begins…

  3. Loop quantization of the polarized Gowdy model on T{sup 3}: classical theory

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Kinjal; Date, Ghanashyam [Institute of Mathematical Sciences, CIT Campus, Chennai-600 113 (India)], E-mail: kinjal@imsc.res.in, E-mail: shyam@imsc.res.in

    2008-05-21

    The vacuum Gowdy models provide much studied, non-trivial midi-superspace examples. Various technical issues within loop quantum gravity can be studied in these models and one can hope to understand singularities and their resolution in the loop quantization. The first step in this program is to reformulate the model in real connection variables in a manner that is amenable to loop quantization. We begin with the unpolarized model and carry out a consistent reduction to the polarized case. Carrying out complete gauge fixing, the known solutions are recovered.

  4. 3D DD modelling of the prismatic loops and dislocations interaction in pure iron

    International Nuclear Information System (INIS)

    Novokshanov, R.; Roberts, S.

    2007-01-01

    Full text of publication follows: Neutron irradiation can increase the yield stress and reduce the ductility of metals. These effects are mainly caused by the interaction of dislocations with damage produced during irradiation. In iron irradiated with fast neutrons the damage takes the form of 1/2 and 1/2 prismatic dislocation loops (the size of the loops varies from 2 nm to 20 nm depending on the dose of irradiation). The interaction between such loops and dislocations is the subject of this research. 3D dislocation dynamics simulations have been carried out to model the interaction between prismatic loops and dis- locations in pure iron subject to uniaxial loading conditions. The primary goal was to understand the mechanism of interaction of a a/2 loop and a mobile dislocation. The simulations have shown a complicated 3D interaction resulting in either bowing around an obstacle (prismatic loop, Orowan mechanism) or cutting it through, carrying part of the loop away and leaving the other part behind. Cross-slip can be important, in a manner depending on the type of mobile dislocation, size, type and orientation of prismatic loop. The secondary goal was to investigate the dependence of the critical stress needed for dislocations to overcome the obstacles as a function of: size of loops, initial separation between loops, the direction of motion of the mobile dislocation and its type (pure edge or screw), and type of a loop (interstitial or vacancy). Many different configurations have been simulated. The size of the loops was varied from 10 nm to 100 nm; the separation between the loops in a row was varied from one to four loop diameters; the distance between the glide plane and the loop plane was varied from 0 to 20 nm. The glide plane of the mobile dislocation was either perpendicular to and or inclined to the loop plane. The results show a strong dependence of the critical stress on the size of the loops and the initial configuration. (authors)

  5. Protein loop modeling using a new hybrid energy function and its application to modeling in inaccurate structural environments.

    Directory of Open Access Journals (Sweden)

    Hahnbeom Park

    Full Text Available Protein loop modeling is a tool for predicting protein local structures of particular interest, providing opportunities for applications involving protein structure prediction and de novo protein design. Until recently, the majority of loop modeling methods have been developed and tested by reconstructing loops in frameworks of experimentally resolved structures. In many practical applications, however, the protein loops to be modeled are located in inaccurate structural environments. These include loops in model structures, low-resolution experimental structures, or experimental structures of different functional forms. Accordingly, discrepancies in the accuracy of the structural environment assumed in development of the method and that in practical applications present additional challenges to modern loop modeling methods. This study demonstrates a new strategy for employing a hybrid energy function combining physics-based and knowledge-based components to help tackle this challenge. The hybrid energy function is designed to combine the strengths of each energy component, simultaneously maintaining accurate loop structure prediction in a high-resolution framework structure and tolerating minor environmental errors in low-resolution structures. A loop modeling method based on global optimization of this new energy function is tested on loop targets situated in different levels of environmental errors, ranging from experimental structures to structures perturbed in backbone as well as side chains and template-based model structures. The new method performs comparably to force field-based approaches in loop reconstruction in crystal structures and better in loop prediction in inaccurate framework structures. This result suggests that higher-accuracy predictions would be possible for a broader range of applications. The web server for this method is available at http://galaxy.seoklab.org/loop with the PS2 option for the scoring function.

  6. Mathematical model of the Drosophila circadian clock: loop regulation and transcriptional integration.

    Science.gov (United States)

    Fathallah-Shaykh, Hassan M; Bona, Jerry L; Kadener, Sebastian

    2009-11-04

    Eukaryotic circadian clocks include interconnected positive and negative feedback loops. The clock-cycle dimer (CLK-CYC) and its homolog, CLK-BMAL1, are key transcriptional activators of central components of the Drosophila and mammalian circadian networks, respectively. In Drosophila, negative loops include period-timeless and vrille; positive loops include par domain protein 1. Clockwork orange (CWO) is a recently discovered negative transcription factor with unusual effects on period, timeless, vrille, and par domain protein 1. To understand the actions of this protein, we introduced a new system of ordinary differential equations to model regulatory networks. The model is faithful in the sense that it replicates biological observations. CWO loop actions elevate CLK-CYC; the transcription of direct targets responds by integrating opposing signals from CWO and CLK-CYC. Loop regulation and integration of opposite transcriptional signals appear to be central mechanisms as they also explain paradoxical effects of period gain-of-function and null mutations.

  7. Effects of probiotics and antibiotics on the intestinal homeostasis in a computer controlled model of the large intestine

    Directory of Open Access Journals (Sweden)

    Rehman Ateequr

    2012-03-01

    Full Text Available Abstract Background Antibiotic associated diarrhea and Clostridium difficile infection are frequent complications of broad spectrum antibiotic therapy. Probiotic bacteria are used as therapeutic and preventive agents in these disorders, but the exact functional mechanisms and the mode of action are poorly understood. The effects of clindamycin and the probiotic mixture VSL#3 (containing the 8 bacterial strains Streptococcus thermophilus, Bifidobacterium breve, Bifidobacterium longum, Bifidobacterium infantis, Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus paracasei and Lactobacillus delbrueckii subsp. Bulgaricus consecutively or in combination were investigated and compared to controls without therapy using a standardized human fecal microbiota in a computer-controlled in vitro model of large intestine. Microbial metabolites (short chain fatty acids, lactate, branched chain fatty acids, and ammonia and the intestinal microbiota were analyzed. Results Compared to controls and combination therapy, short chain fatty acids and lactate, but also ammonia and branched chain fatty acids, were increased under probiotic therapy. The metabolic pattern under combined therapy with antibiotics and probiotics had the most beneficial and consistent effect on intestinal metabolic profiles. The intestinal microbiota showed a decrease in several indigenous bacterial groups under antibiotic therapy, there was no significant recovery of these groups when the antibiotic therapy was followed by administration of probiotics. Simultaneous application of anti- and probiotics had a stabilizing effect on the intestinal microbiota with increased bifidobacteria and lactobacilli. Conclusions Administration of VSL#3 parallel with the clindamycin therapy had a beneficial and stabilizing effect on the intestinal metabolic homeostasis by decreasing toxic metabolites and protecting the endogenic microbiota from destruction. Probiotics could be a reasonable

  8. A mathematical model for the simulation of thermal transients in the water loop of IPEN

    International Nuclear Information System (INIS)

    Pontedeiro, A.C.

    1980-01-01

    A mathematical model for simulation of thermal transients in the water loop at the Instituto de Pesquisas Energeticas e Nucleares, Sao Paulo, Brasil, is developed. The model is based on energy equations applied to the components of the experimental water loop. The non-linear system of first order diferencial equations and of non-linear algebraic equations obtained through the utilization of the IBM 'System/360-Continous System Modeling Program' (CSMP) is resolved. An optimization of the running time of the computer is made and a typical simulation of the water loop is executed. (Author) [pt

  9. Modelling and characterization of an airlift-loop bioreactor

    NARCIS (Netherlands)

    Verlaan, P.

    1987-01-01

    An airlift-loop reactor is a bioreactor for aerobic biotechnological processes. The special feature of the ALR is the recirculation of the liquid through a downcomer connecting the top and the bottom of the main bubbling section. Due to the high circulation-flow rate, efficient mixing and

  10. Alternative Functional In Vitro Models of Human Intestinal Epithelia

    Directory of Open Access Journals (Sweden)

    Amanda L Kauffman

    2013-07-01

    Full Text Available Physiologically relevant sources of absorptive intestinal epithelial cells are crucial for human drug transport studies. Human adenocarcinoma-derived intestinal cell lines, such as Caco-2, offer conveniences of easy culture maintenance and scalability, but do not fully recapitulate in vivo intestinal phenotypes. Additional sources of renewable physiologically relevant human intestinal cells would provide a much needed tool for drug discovery and intestinal physiology. We sought to evaluate and compare two alternative sources of human intestinal cells, commercially available primary human intestinal epithelial cells (hInEpCs and induced pluripotent stem cell (iPSC-derived intestinal cells to Caco-2, for use in in vitro transwell monolayer intestinal transport assays. To achieve this for iPSC-derived cells, our previously described 3-dimensional intestinal organogenesis method was adapted to transwell differentiation. Intestinal cells were assessed by marker expression through immunocytochemical and mRNA expression analyses, monolayer integrity through Transepithelial Electrical Resistance (TEER measurements and molecule permeability, and functionality by taking advantage the well-characterized intestinal transport mechanisms. In most cases, marker expression for primary hInEpCs and iPSC-derived cells appeared to be as good as or better than Caco-2. Furthermore, transwell monolayers exhibited high TEER with low permeability. Primary hInEpCs showed molecule efflux indicative of P-glycoprotein transport. Primary hInEpCs and iPSC-derived cells also showed neonatal Fc receptor-dependent binding of immunoglobulin G variants. Primary hInEpCs and iPSC-derived intestinal cells exhibit expected marker expression and demonstrate basic functional monolayer formation, similar to or better than Caco-2. These cells could offer an alternative source of human intestinal cells for understanding normal intestinal epithelial physiology and drug transport.

  11. A self-organizing algorithm for modeling protein loops.

    Directory of Open Access Journals (Sweden)

    Pu Liu

    2009-08-01

    Full Text Available Protein loops, the flexible short segments connecting two stable secondary structural units in proteins, play a critical role in protein structure and function. Constructing chemically sensible conformations of protein loops that seamlessly bridge the gap between the anchor points without introducing any steric collisions remains an open challenge. A variety of algorithms have been developed to tackle the loop closure problem, ranging from inverse kinematics to knowledge-based approaches that utilize pre-existing fragments extracted from known protein structures. However, many of these approaches focus on the generation of conformations that mainly satisfy the fixed end point condition, leaving the steric constraints to be resolved in subsequent post-processing steps. In the present work, we describe a simple solution that simultaneously satisfies not only the end point and steric conditions, but also chirality and planarity constraints. Starting from random initial atomic coordinates, each individual conformation is generated independently by using a simple alternating scheme of pairwise distance adjustments of randomly chosen atoms, followed by fast geometric matching of the conformationally rigid components of the constituent amino acids. The method is conceptually simple, numerically stable and computationally efficient. Very importantly, additional constraints, such as those derived from NMR experiments, hydrogen bonds or salt bridges, can be incorporated into the algorithm in a straightforward and inexpensive way, making the method ideal for solving more complex multi-loop problems. The remarkable performance and robustness of the algorithm are demonstrated on a set of protein loops of length 4, 8, and 12 that have been used in previous studies.

  12. One-Loop Renormalizable Wess-Zumino Model on Bosonic-Fermionic Noncommutative Superspace

    OpenAIRE

    Miao, Yan-Gang; Wang, Xu-Dong

    2014-01-01

    We construct a deformed Wess-Zumino model on the noncommutative superspace where the Bosonic and Fermionic coordinates are no longer commutative with each other. Using the background field method, we calculate the primary one-loop effective action based on the deformed action. By comparing the two actions, we find that the deformed Wess-Zumino model is not renormalizable. To obtain a renormalizable model, we combine the primary one-loop effective action with the deformed action, and then calc...

  13. Four-loop beta function in the Wess-Zumino model

    International Nuclear Information System (INIS)

    Avdeev, L.V.; Gorishny, S.G.

    1982-01-01

    A method for calculating momentum integrals, proposed by Chetyrkin and Tkachov, is applied to the foUr-loop calculations of the ν-function in the Wess-Zumino model. The main advantage of the used method is the existence of a relatively simple calculational algorithm that allows one to write an effective computer program on the system of analytical evaluations SCHOONSCHIP. Any three-loop integral with one external momentum can be computed by this program. The four-loop calculation in the WZ model is one of the first and simplest applications of the program

  14. Calibration of steady-state car-following models using macroscopic loop detector data.

    Science.gov (United States)

    2010-05-01

    The paper develops procedures for calibrating the steady-state component of various car following models using : macroscopic loop detector data. The calibration procedures are developed for a number of commercially available : microscopic traffic sim...

  15. THERMAL NON-EQUILIBRIUM REVISITED: A HEATING MODEL FOR CORONAL LOOPS

    International Nuclear Information System (INIS)

    Lionello, Roberto; Linker, Jon A.; Mikić, Zoran; Winebarger, Amy R.; Mok, Yung

    2013-01-01

    The location and frequency of events that heat the million-degree corona are still a matter of debate. One potential heating scenario is that the energy release is effectively steady and highly localized at the footpoints of coronal structures. Such an energy deposition drives thermal non-equilibrium solutions in the hydrodynamic equations in longer loops. This heating scenario was considered and discarded by Klimchuk et al. on the basis of their one-dimensional simulations as incapable of reproducing observational characteristics of loops. In this paper, we use three-dimensional simulations to generate synthetic emission images, from which we select and analyze six loops. The main differences between our model and that of Klimchuk et al. concern (1) dimensionality, (2) resolution, (3) geometrical properties of the loops, (4) heating function, and (5) radiative function. We find evidence, in this small set of simulated loops, that the evolution of the light curves, the variation of temperature along the loops, the density profile, and the absence of small-scale structures are compatible with the characteristics of observed loops. We conclude that quasi-steady footpoint heating that drives thermal non-equilibrium solutions cannot yet be ruled out as a viable heating scenario for EUV loops

  16. Model-based estimation of loop gain using spontaneous breathing: A validation study

    Science.gov (United States)

    Gederi, Elnaz; Nemati, Shamim; Edwards, Bradley A.; Clifford, Gari D.; Malhotra, Atul; Wellman, Andrew

    2014-01-01

    Non-invasive assessment of ventilatory control stability or loop gain (which is a key contributor in a number of sleep-related breathing disorders) has proven to be cumbersome. We present a novel multivariate autoregressive model that we hypothesize will enable us to make time-varying measurements of loop gain using nothing more than spontaneous fluctuations in ventilation and CO2. The model is adaptive to changes in the feedback control loop and therefore can account for system non-stationarities (e.g. changes in sleep state) and it is resistant to artifacts by using a signal quality measure. We tested this method by assessing its ability to detect a known increase in loop gain induced by proportional assist ventilation (PAV). Subjects were studied during sleep while breathing on continuous positive airway pressure (CPAP) alone (to stabilize the airway) or on CPAP + PAV. We show that the method tracked the PAV-induced increase in loop gain, demonstrating its time-varying capabilities, and it remained accurate in the face of measurement related artifacts. The model was able to detect a statistically significant increase in loop gain from 0.14 ± 10 on CPAP alone to 0.21 ± 0.13 on CPAP + PAV (p PAV-induced increase in loop gain was predominantly driven by an increase in controller gain. Taken together, these data provide compelling evidence for the validity of this technique. PMID:25038522

  17. Mathematical Modeling of Intestinal Iron Absorption Using Genetic Programming.

    Science.gov (United States)

    Colins, Andrea; Gerdtzen, Ziomara P; Nuñez, Marco T; Salgado, J Cristian

    2017-01-01

    Iron is a trace metal, key for the development of living organisms. Its absorption process is complex and highly regulated at the transcriptional, translational and systemic levels. Recently, the internalization of the DMT1 transporter has been proposed as an additional regulatory mechanism at the intestinal level, associated to the mucosal block phenomenon. The short-term effect of iron exposure in apical uptake and initial absorption rates was studied in Caco-2 cells at different apical iron concentrations, using both an experimental approach and a mathematical modeling framework. This is the first report of short-term studies for this system. A non-linear behavior in the apical uptake dynamics was observed, which does not follow the classic saturation dynamics of traditional biochemical models. We propose a method for developing mathematical models for complex systems, based on a genetic programming algorithm. The algorithm is aimed at obtaining models with a high predictive capacity, and considers an additional parameter fitting stage and an additional Jackknife stage for estimating the generalization error. We developed a model for the iron uptake system with a higher predictive capacity than classic biochemical models. This was observed both with the apical uptake dataset used for generating the model and with an independent initial rates dataset used to test the predictive capacity of the model. The model obtained is a function of time and the initial apical iron concentration, with a linear component that captures the global tendency of the system, and a non-linear component that can be associated to the movement of DMT1 transporters. The model presented in this paper allows the detailed analysis, interpretation of experimental data, and identification of key relevant components for this complex biological process. This general method holds great potential for application to the elucidation of biological mechanisms and their key components in other complex

  18. Modelling of dielectric hysteresis loops in ferroelectric semiconductors with charged defects

    International Nuclear Information System (INIS)

    Morozovska, Anna N; Eliseev, Eugene A

    2004-01-01

    We have proposed the phenomenological description of dielectric hysteresis loops in ferroelectric semiconductors with charged defects and prevailing extrinsic conductivity. We have modified the Landau-Ginsburg approach and shown that the macroscopic state of the aforementioned inhomogeneous system can be described by three coupled equations for three order parameters. Both the experimentally observed coercive field values well below the thermodynamic values and the various hysteresis-loop deformations (constricted and double loops) have been obtained in the framework of our model. The obtained results quantitatively explain the ferroelectric switching in such ferroelectric materials as thick PZT films

  19. Exchange bias and asymmetric hysteresis loops from a microscopic model of core/shell nanoparticles

    International Nuclear Information System (INIS)

    Iglesias, Oscar; Batlle, Xavier; Labarta, Amilcar

    2007-01-01

    We present Monte Carlo simulations of hysteresis loops of a model of a magnetic nanoparticle with a ferromagnetic core and an antiferromagnetic shell with varying values of the core/shell interface exchange coupling which aim to clarify the microscopic origin of exchange bias observed experimentally. We have found loop shifts in the field direction as well as displacements along the magnetization axis that increase in magnitude when increasing the interfacial exchange coupling. Overlap functions computed from the spin configurations along the loops have been obtained to explain the origin and magnitude of these features microscopically

  20. Probing the closed-loop model of mRNA translation in living cells

    OpenAIRE

    Archer, Stuart K; Shirokikh, Nikolay E; Hallwirth, Claus V; Beilharz, Traude H; Preiss, Thomas

    2015-01-01

    The mRNA closed-loop, formed through interactions between the cap structure, poly(A) tail, eIF4E, eIF4G and PAB, features centrally in models of eukaryotic translation initiation, although direct support for its existence in vivo is not well established. Here, we investigated the closed-loop using a combination of mRNP isolation from rapidly cross-linked cells and high-throughput qPCR. Using the interaction between these factors and the opposing ends of mRNAs as a proxy for the closed-loop, w...

  1. Properties of loop equations for the Hermitean matrix model and for two-dimensional quantum gravity

    International Nuclear Information System (INIS)

    Ambjoern, J.; Makeenko, Yu.M.

    1990-05-01

    We study properties of the loop equations for the NxN Hermitean matrix model with arbitrary (even) interaction as well as of their continuum limit, associated with the two-dimensional quantum gravity. We apply the general procedure of iterative solution proposed recently by David. We relate the specific heat to the singular behavior of the connected correlator of two loops. We solve the continuum equation to a few lower orders in the string coupling constant, obtaining results for macroscopic loops, including the case of a multicritical fixed point. (orig.)

  2. Estimation of Model Uncertainties in Closed-loop Systems

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Poulsen, Niels Kjølstad

    2008-01-01

    This paper describe a method for estimation of parameters or uncertainties in closed-loop systems. The method is based on an application of the dual YJBK (after Youla, Jabr, Bongiorno and Kucera) parameterization of all systems stabilized by a given controller. The dual YJBK transfer function...... is a measure for the variation in the system seen through the feedback controller. It is shown that it is possible to isolate a certain number of parameters or uncertain blocks in the system exactly. This is obtained by modifying the feedback controller through the YJBK transfer function together with pre...

  3. Precision-cut intestinal slices as an in vitro model to predict NSAID induced intestinal toxicity

    NARCIS (Netherlands)

    Niu, Xiaoyu; van der Bijl, Henk; Groothuis, Geny; de Graaf, Inge

    2013-01-01

    Non-steroidal anti-inflammatory drugs (NSAIDs) are associated with high prevalence of gastro-intestinal side-effects. In vivo studies suggest that uncoupling of oxidative phosphorylation is an important cause of the toxicity and that the toxicity is aggravated by enterohepatic circulation.

  4. Digestion of starch in a dynamic small intestinal model.

    Science.gov (United States)

    Jaime-Fonseca, M R; Gouseti, O; Fryer, P J; Wickham, M S J; Bakalis, S

    2016-12-01

    The rate and extent of starch digestion have been linked with important health aspects, such as control of obesity and type-2 diabetes. In vitro techniques are often used to study digestion and simulated nutrient absorption; however, the effect of gut motility is often disregarded. The present work aims at studying fundamentals of starch digestion, e.g. the effect of viscosity on digestibility, taking into account both biochemical and engineering (gut motility) parameters. New small intestinal model (SIM) that realistically mimics gut motility (segmentation) was used to study digestibility and simulated oligosaccharide bio accessibility of (a) model starch solutions; (b) bread formulations. First, the model was compared with the rigorously mixed stirred tank reactor (STR). Then the effects of enzyme concentration/flow rate, starch concentration, and digesta viscosity (addition of guar gum) were evaluated. Compared to the STR, the SIM showed presence of lag phase when no digestive processes could be detected. The effects of enzyme concentration and flow rate appeared to be marginal in the region of mass transfer limited reactions. Addition of guar gum reduced simulated glucose absorption by up to 45 % in model starch solutions and by 35 % in bread formulations, indicating the importance of chyme rheology on nutrient bioaccessibility. Overall, the work highlights the significance of gut motility in digestive processes and offers a powerful tool in nutritional studies that, additionally to biochemical, considers engineering aspects of digestion. The potential to modulate food digestibility and nutrient bioaccessibility by altering food formulation is indicated.

  5. Analysis of a fully packed loop model arising in a magnetic Coulomb phase.

    Science.gov (United States)

    Jaubert, L D C; Haque, M; Moessner, R

    2011-10-21

    The Coulomb phase of spin ice, and indeed the I(c) phase of water ice, naturally realize a fully packed two-color loop model in 3D. We present a detailed analysis of the statistics of these loops: we find loops spanning the system multiple times hosting a finite fraction of all sites while the average loop length remains finite. We contrast the behavior with an analogous 2D model. We connect this body of results to properties of polymers, percolation and insights from Schramm-Loewner evolution processes. We also study another extended degree of freedom, called worms, which appear as "Dirac strings" in spin ice. We discuss implications of these results for the efficiency of numerical cluster algorithms, and address implications for the ordering properties of a broader class of magnetic systems, e.g., with Heisenberg spins, such as CsNiCrF(6) or ZnCr(2)O(4). © 2011 American Physical Society

  6. Two-loop effective potential for Wess-Zumino model using superfields

    International Nuclear Information System (INIS)

    Santos, R.P. dos; Srivastava, P.P.

    1985-10-01

    For the case of several interacting chiral superfields the propagators for the unconstrained superfield potentials in the 'shifted' theory, where the supersymmetry is explicitly broken, are derived in a compact form. They are used to compute one-loop effective potential in the general case, while a superfield calculation of renormalized effective potential to two loops for the Wess-Zumino model is performed. (author)

  7. Operator product expansion of higher rank Wilson loops from D-branes and matrix models

    International Nuclear Information System (INIS)

    Giombi, Simone; Ricci, Riccardo; Trancanelli, Diego

    2006-01-01

    In this paper we study correlation functions of circular Wilson loops in higher dimensional representations with chiral primary operators of N = 4 super Yang-Mills theory. This is done using the recently established relation between higher rank Wilson loops in gauge theory and D-branes with electric fluxes in supergravity. We verify our results with a matrix model computation, finding perfect agreement in both the symmetric and the antisymmetric case

  8. Local and Remote Postconditioning Decrease Intestinal Injury in a Rabbit Ischemia/Reperfusion Model

    Directory of Open Access Journals (Sweden)

    Mu Yang

    2016-01-01

    Full Text Available Intestinal ischemia/reperfusion (I/R injury is a significant problem that is associated with high morbidity and mortality in critical settings. This injury may be ameliorated using postconditioning protocol. In our study, we created a rabbit intestinal I/R injury model to analyze the effects of local ischemia postconditioning (LIPo and remote ischemia postconditioning (RIPo on intestinal I/R injury. We concluded that LIPo affords protection in intestinal I/R injury in a comparable fashion with RIPo by decreasing oxidative stress, neutrophil activation, and apoptosis.

  9. Pathology of Rodent Models of Intestinal Cancer: Progress Report and Recommendations

    Science.gov (United States)

    Washington, Mary Kay; Powell, Anne E.; Sullivan, Ruth; Sundberg, John; Wright, Nicholas; Coffey, Robert J.; Dove, William F.

    2013-01-01

    In October 2010, a pathology review of rodent models of intestinal neoplasia was held at The Jackson Laboratory. This review complemented 2 other concurrent events: a workshop on methods of modeling colon cancer in rodents and a conference on current issues in murine and human colon cancer. We summarize the results of the pathology review and the committee’s recommendations for tumor nomenclature. A virtual high-resolution image slide box of these models has been developed. This report discusses significant recent developments in rodent modeling of intestinal neoplasia, including the role of stem cells in cancer and the creation of models of metastatic intestinal cancer. PMID:23415801

  10. Enthalpy-Based Thermal Evolution of Loops: III. Comparison of Zero-Dimensional Models

    Science.gov (United States)

    Cargill, P. J.; Bradshaw, Stephen J.; Klimchuk, James A.

    2012-01-01

    Zero dimensional (0D) hydrodynamic models, provide a simple and quick way to study the thermal evolution of coronal loops subjected to time-dependent heating. This paper presents a comparison of a number of 0D models that have been published in the past and is intended to provide a guide for those interested in either using the old models or developing new ones. The principal difference between the models is the way the exchange of mass and energy between corona, transition region and chromosphere is treated, as plasma cycles into and out of a loop during a heating-cooling cycle. It is shown that models based on the principles of mass and energy conservation can give satisfactory results at some, or, in the case of the Enthalpy Based Thermal Evolution of Loops (EBTEL) model, all stages of the loop evolution. Empirical models can lead to low coronal densities, spurious delays between the peak density and temperature, and, for short heating pulses, overly short loop lifetimes.

  11. Enthalpy-Based Thermal Evolution of Loops: II. Improvements to the Model

    Science.gov (United States)

    Cargill, P. J.; Bradshaw, S. J.; Klimchuk, J. A.

    2011-01-01

    This paper further develops the zero-dimensional (0D) hydrodynamic coronal loop model "Enthalpy-based Thermal Evolution of Loops" (EBTEL) originally proposed by Klimchuk et al (2008), which studies the plasma response to evolving coronal heating. It has typically been applied to impulsive heating events. The basis of EBTEL is the modelling of mass exchange between the corona and transition region and chromosphere in response to heating variations, with the key parameter being the ratio of transition region to coronal radiation. We develop new models for this parameter that now include gravitational stratification and a physically motivated approach to radiative cooling. A number of examples are presented, including nanoflares in short and long loops, and a small flare. It is found that while the evolution of the loop temperature is rather insensitive to the details of the model, accurate tracking of the density requires the inclusion of our new features. In particular, we are able to now obtain highly over-dense loops in the late cooling phase and decreases to the coronal density arising due to stratification. The 0D results are compared to a 1D hydro code (Hydrad). The agreement is acceptable, with the exception of the flare case where some versions of Hydrad can give significantly lower densities. This is attributed to the method used to model the chromosphere in a flare. EBTEL is suitable for general use as a tool for (a) quick-look results of loop evolution in response to a given heating function and (b) situations where the modelling of hundreds or thousands of elemental loops is needed. A single run takes a few seconds on a contemporary laptop.

  12. Using video modeling with substitutable loops to teach varied play to children with autism.

    Science.gov (United States)

    Dupere, Sally; MacDonald, Rebecca P F; Ahearn, William H

    2013-01-01

    Children with autism often engage in repetitive play with little variation in the actions performed or items used. This study examined the use of video modeling with scripted substitutable loops on children's pretend play with trained and untrained characters. Three young children with autism were shown a video model of scripted toy play that included a substitutable loop that allowed various characters to perform the same actions and vocalizations. Three characters were modeled with the substitutable loop during training sessions, and 3 additional characters were present in the video but never modeled. Following video modeling, all the participants incorporated untrained characters into their play, but the extent to which they did so varied. © Society for the Experimental Analysis of Behavior.

  13. Closed-loop model identification of cooperative manipulators holding deformable objects

    Science.gov (United States)

    Alkathiri, A. A.; Akmeliawati, R.; Azlan, N. Z.

    2017-11-01

    This paper presents system identification to obtain the closed-loop models of a couple of cooperative manipulators in a system, which function to hold deformable objects. The system works using the master-slave principle. In other words, one of the manipulators is position-controlled through encoder feedback, while a force sensor gives feedback to the other force-controlled manipulator. Using the closed-loop input and output data, the closed-loop models, which are useful for model-based control design, are estimated. The criteria for model validation are a 95% fit between the measured and simulated output of the estimated models and residual analysis. The results show that for both position and force control respectively, the fits are 95.73% and 95.88%.

  14. Model-based closed-loop glucose control in type 1 diabetes

    DEFF Research Database (Denmark)

    Schmidt, Signe; Boiroux, Dimitri; Duun-Henriksen, Anne Katrine

    2013-01-01

    To improve type 1 diabetes mellitus (T1DM) management, we developed a model predictive control (MPC) algorithm for closed-loop (CL) glucose control based on a linear second-order deterministic-stochastic model. The deterministic part of the model is specified by three patient-specific parameters...

  15. A novel double loop control model design for chemical unstable processes.

    Science.gov (United States)

    Cong, Er-Ding; Hu, Ming-Hui; Tu, Shan-Tung; Xuan, Fu-Zhen; Shao, Hui-He

    2014-03-01

    In this manuscript, based on Smith predictor control scheme for unstable process in industry, an improved double loop control model is proposed for chemical unstable processes. Inner loop is to stabilize integrating the unstable process and transform the original process to first-order plus pure dead-time dynamic stable process. Outer loop is to enhance the performance of set point response. Disturbance controller is designed to enhance the performance of disturbance response. The improved control system is simple with exact physical meaning. The characteristic equation is easy to realize stabilization. Three controllers are separately design in the improved scheme. It is easy to design each controller and good control performance for the respective closed-loop transfer function separately. The robust stability of the proposed control scheme is analyzed. Finally, case studies illustrate that the improved method can give better system performance than existing design methods. © 2013 ISA Published by ISA All rights reserved.

  16. Human organoids: a model system for intestinal diseases

    OpenAIRE

    Wiegerinck, C.L.

    2015-01-01

    You are what you eat. A common saying that indicates that your physical or mental state can be influenced by your choice of food. Unfortunately, not all people have the luxury to choose what to eat; this can be related to place of birth, social, economic state, or the physical inability of the diseased intestine to take up certain food. A cell layer, the epithelium, covers the intestine, and harbors the main functions of the intestine: uptake, digestion of food, and a barrier against unwanted...

  17. Wind turbine model and loop shaping controller design

    Science.gov (United States)

    Gilev, Bogdan

    2017-12-01

    A model of a wind turbine is evaluated, consisting of: wind speed model, mechanical and electrical model of generator and tower oscillation model. Model of the whole system is linearized around of a nominal point. By using the linear model with uncertainties is synthesized a uncertain model. By using the uncertain model is developed a H∞ controller, which provide mode of stabilizing the rotor frequency and damping the tower oscillations. Finally is simulated work of nonlinear system and H∞ controller.

  18. Prenatal Intestinal Obstruction Affects the Myenteric Plexus and Causes Functional Bowel Impairment in Fetal Rat Experimental Model of Intestinal Atresia

    Science.gov (United States)

    Khen-Dunlop, Naziha; Sarnacki, Sabine; Victor, Anais; Grosos, Celine; Menard, Sandrine; Soret, Rodolphe; Goudin, Nicolas; Pousset, Maud; Sauvat, Frederique; Revillon, Yann; Cerf-Bensussan, Nadine; Neunlist, Michel

    2013-01-01

    Background Intestinal atresia is a rare congenital disorder with an incidence of 3/10 000 birth. About one-third of patients have severe intestinal dysfunction after surgical repair. We examined whether prenatal gastrointestinal obstruction might effect on the myenteric plexus and account for subsequent functional disorders. Methodology/Principal Findings We studied a rat model of surgically induced antenatal atresia, comparing intestinal samples from both sides of the obstruction and with healthy rat pups controls. Whole-mount preparations of the myenteric plexus were stained for choline acetyltransferase (ChAT) and nitric oxide synthase (nNOS). Quantitative reverse transcription PCR was used to analyze mRNAs for inflammatory markers. Functional motility and permeability analyses were performed in vitro. Phenotypic studies were also performed in 8 newborns with intestinal atresia. In the experimental model, the proportion of nNOS-immunoreactive neurons was similar in proximal and distal segments (6.7±4.6% vs 5.6±4.2%, p = 0.25), but proximal segments contained a higher proportion of ChAT-immunoreactive neurons (13.2±6.2% vs 7.5±4.3%, p = 0.005). Phenotypic changes were associated with a 100-fold lower concentration-dependent contractile response to carbachol and a 1.6-fold higher EFS-induced contractile response in proximal compared to distal segments. Transcellular (p = 0.002) but not paracellular permeability was increased. Comparison with controls showed that modifications involved not only proximal but also distal segments. Phenotypic studies in human atresia confirmed the changes in ChAT expression. Conclusion Experimental atresia in fetal rat induces differential myenteric plexus phenotypical as well as functional changes (motility and permeability) between the two sides of the obstruction. Delineating these changes might help to identify markers predictive of motility dysfunction and to define guidelines for post-surgical care. PMID:23667464

  19. Empirical potential and elasticity theory modelling of interstitial dislocation loops in UO2 for cluster dynamics application

    International Nuclear Information System (INIS)

    Le-Prioux, Arno

    2017-01-01

    During irradiation in reactor, the microstructure of UO 2 changes and deteriorates, causing modifications of its physical and mechanical properties. The kinetic models used to describe these changes such as cluster dynamics (CRESCENDO calculation code) consider the main microstructural elements that are cavities and interstitial dislocation loops, and provide a rather rough description of the loop thermodynamics. In order to tackle this issue, this work has led to the development of a thermodynamic model of interstitial dislocation loops based on empirical potential calculations. The model considers two types of interstitial dislocation loops on two different size domains: Type 1: Dislocation loops similar to Frank partials in F.C.C. materials which are stable in the smaller size domain. Type 2: Perfect dislocation loops of Burgers vector (a/2)(110) stable in the larger size domain. The analytical formula used to compute the interstitial dislocation loop formation energies is the one for circular loops which has been modified in order to take into account the effects of the dislocation core, which are significant at smaller sizes. The parameters have been determined by empirical potential calculations of the formation energies of prismatic pure edge dislocation loops. The effect of the habit plane reorientation on the formation energies of perfect dislocation loops has been taken into account by a simple interpolation method. All the different types of loops seen during TEM observations are thus accounted for by the model. (author) [fr

  20. Oral Administration of Escin Inhibits Acute Inflammation and Reduces Intestinal Mucosal Injury in Animal Models

    OpenAIRE

    Li, Minmin; Lu, Chengwen; Zhang, Leiming; Zhang, Jianqiao; Du, Yuan; Duan, Sijin; Wang, Tian; Fu, Fenghua

    2015-01-01

    The present study aimed to investigate the effects of oral administration of escin on acute inflammation and intestinal mucosal injury in animal models. The effects of escin on carrageenan-induced paw edema in a rat model of acute inflammation, cecal ligation and puncture (CLP) induced intestinal mucosal injury in a mouse model, were observed. It was shown that oral administration of escin inhibits carrageenan-induced paw edema and decreases the production of prostaglandin E2 (PGE2) and cyclo...

  1. Oral Administration of Escin Inhibits Acute Inflammation and Reduces Intestinal Mucosal Injury in Animal Models

    Directory of Open Access Journals (Sweden)

    Minmin Li

    2015-01-01

    Full Text Available The present study aimed to investigate the effects of oral administration of escin on acute inflammation and intestinal mucosal injury in animal models. The effects of escin on carrageenan-induced paw edema in a rat model of acute inflammation, cecal ligation and puncture (CLP induced intestinal mucosal injury in a mouse model, were observed. It was shown that oral administration of escin inhibits carrageenan-induced paw edema and decreases the production of prostaglandin E2 (PGE2 and cyclooxygenase- (COX- 2. In CLP model, low dose of escin ameliorates endotoxin induced liver injury and intestinal mucosal injury and increases the expression of tight junction protein claudin-5 in mice. These findings suggest that escin effectively inhibits acute inflammation and reduces intestinal mucosal injury in animal models.

  2. Oral Administration of Escin Inhibits Acute Inflammation and Reduces Intestinal Mucosal Injury in Animal Models.

    Science.gov (United States)

    Li, Minmin; Lu, Chengwen; Zhang, Leiming; Zhang, Jianqiao; Du, Yuan; Duan, Sijin; Wang, Tian; Fu, Fenghua

    2015-01-01

    The present study aimed to investigate the effects of oral administration of escin on acute inflammation and intestinal mucosal injury in animal models. The effects of escin on carrageenan-induced paw edema in a rat model of acute inflammation, cecal ligation and puncture (CLP) induced intestinal mucosal injury in a mouse model, were observed. It was shown that oral administration of escin inhibits carrageenan-induced paw edema and decreases the production of prostaglandin E2 (PGE2) and cyclooxygenase- (COX-) 2. In CLP model, low dose of escin ameliorates endotoxin induced liver injury and intestinal mucosal injury and increases the expression of tight junction protein claudin-5 in mice. These findings suggest that escin effectively inhibits acute inflammation and reduces intestinal mucosal injury in animal models.

  3. Simplified Models for Analysis and Design of the Control System Main Loops of CAREM Reactor

    International Nuclear Information System (INIS)

    Etchepareborda, Andres; Flury, Celso

    2000-01-01

    The target of this work is to show a few models developed for control analysis and design of the reactor CAREM's main control loops within a broad range of power (between 40 % and 100%).By one side, it is shown the main features of a analytic model programed in MATLAB.This model is based on fitting steady state points at different power levels of the CAREM's RETRAN model.By the other side, it is shown linear models of black-box type denoting the perturbed behavior of the system for each level power point.These models are identified from temporal responses of CAREM's RETRAN model to perturbed input signals over the different steady power level points.Then the dynamics of these models are verified contrasting the temporal responses of the RETRAN model versus the responses of the MATLAB model and the identified models, in each steady power level point.Also are contrasting the frequency response of the linearization of MATLAB model versus the frequency response of the identified models, in each steady power level point.Either the MATLAB model as the identified models are good enough for the control analysis and design of the three main control loops.The MATLAB model has a few differences against the RETRAN model in the primary pressure output variable, that it must be taken into account in the design of this control loop if this model is used.The aim of these models is to represent in a satisfactory way the dynamics of the plant for a later control analysis and design of the control loops in a frequency range between 0.01 rad/seg and 0.3 rad/seg, and a power range between 40 % and 100 %

  4. Two loop effective Kahler potential of (non)-renormalizable supersymmetric models

    International Nuclear Information System (INIS)

    Groot Nibbelink, S.; Nyawelo, T.S.

    2005-10-01

    We perform a supergraph computation of the effective Kahler potential at one and two loops for general four dimensional N=1 supersymmetric theories described by arbitrary Kahler potential, superpotential and gauge kinetic function. We only insist on gauge invariance of the Kahler potential and the superpotential as we heavily rely on its consequences in the quantum theory. However, we do not require gauge invariance for the gauge kinetic functions, so that our results can also be applied to anomalous theories that involve the Green-Schwarz mechanism. We illustrate our two loop results by considering a few simple models: the (non-)renormalizable Wess-Zumino model and Super Quantum Electrodynamics. (author)

  5. Closing the loop: modelling of heart failure progression from health to end-stage using a meta-analysis of left ventricular pressure-volume loops.

    Science.gov (United States)

    Warriner, David R; Brown, Alistair G; Varma, Susheel; Sheridan, Paul J; Lawford, Patricia; Hose, David R; Al-Mohammad, Abdallah; Shi, Yubing

    2014-01-01

    The American Heart Association (AHA)/American College of Cardiology (ACC) guidelines for the classification of heart failure (HF) are descriptive but lack precise and objective measures which would assist in categorising such patients. Our aim was two fold, firstly to demonstrate quantitatively the progression of HF through each stage using a meta-analysis of existing left ventricular (LV) pressure-volume (PV) loop data and secondly use the LV PV loop data to create stage specific HF models. A literature search yielded 31 papers with PV data, representing over 200 patients in different stages of HF. The raw pressure and volume data were extracted from the papers using a digitising software package and the means were calculated. The data demonstrated that, as HF progressed, stroke volume (SV), ejection fraction (EF%) decreased while LV volumes increased. A 2-element lumped parameter model was employed to model the mean loops and the error was calculated between the loops, demonstrating close fit between the loops. The only parameter that was consistently and statistically different across all the stages was the elastance (Emax). For the first time, the authors have created a visual and quantitative representation of the AHA/ACC stages of LVSD-HF, from normal to end-stage. The study demonstrates that robust, load-independent and reproducible parameters, such as elastance, can be used to categorise and model HF, complementing the existing classification. The modelled PV loops establish previously unknown physiological parameters for each AHA/ACC stage of LVSD-HF, such as LV elastance and highlight that it this parameter alone, in lumped parameter models, that determines the severity of HF. Such information will enable cardiovascular modellers with an interest in HF, to create more accurate models of the heart as it fails.

  6. Closing the loop: modelling of heart failure progression from health to end-stage using a meta-analysis of left ventricular pressure-volume loops.

    Directory of Open Access Journals (Sweden)

    David R Warriner

    Full Text Available INTRODUCTION: The American Heart Association (AHA/American College of Cardiology (ACC guidelines for the classification of heart failure (HF are descriptive but lack precise and objective measures which would assist in categorising such patients. Our aim was two fold, firstly to demonstrate quantitatively the progression of HF through each stage using a meta-analysis of existing left ventricular (LV pressure-volume (PV loop data and secondly use the LV PV loop data to create stage specific HF models. METHODS AND RESULTS: A literature search yielded 31 papers with PV data, representing over 200 patients in different stages of HF. The raw pressure and volume data were extracted from the papers using a digitising software package and the means were calculated. The data demonstrated that, as HF progressed, stroke volume (SV, ejection fraction (EF% decreased while LV volumes increased. A 2-element lumped parameter model was employed to model the mean loops and the error was calculated between the loops, demonstrating close fit between the loops. The only parameter that was consistently and statistically different across all the stages was the elastance (Emax. CONCLUSIONS: For the first time, the authors have created a visual and quantitative representation of the AHA/ACC stages of LVSD-HF, from normal to end-stage. The study demonstrates that robust, load-independent and reproducible parameters, such as elastance, can be used to categorise and model HF, complementing the existing classification. The modelled PV loops establish previously unknown physiological parameters for each AHA/ACC stage of LVSD-HF, such as LV elastance and highlight that it this parameter alone, in lumped parameter models, that determines the severity of HF. Such information will enable cardiovascular modellers with an interest in HF, to create more accurate models of the heart as it fails.

  7. String states, loops and effective actions in noncommutative field theory and matrix models

    Energy Technology Data Exchange (ETDEWEB)

    Steinacker, Harold C., E-mail: harold.steinacker@univie.ac.at

    2016-09-15

    Refining previous work by Iso, Kawai and Kitazawa, we discuss bi-local string states as a tool for loop computations in noncommutative field theory and matrix models. Defined in terms of coherent states, they exhibit the stringy features of noncommutative field theory. This leads to a closed form for the 1-loop effective action in position space, capturing the long-range non-local UV/IR mixing for scalar fields. The formalism applies to generic fuzzy spaces. The non-locality is tamed in the maximally supersymmetric IKKT or IIB model, where it gives rise to supergravity. The linearized supergravity interactions are obtained directly in position space at one loop using string states on generic noncommutative branes.

  8. String states, loops and effective actions in noncommutative field theory and matrix models

    Directory of Open Access Journals (Sweden)

    Harold C. Steinacker

    2016-09-01

    Full Text Available Refining previous work by Iso, Kawai and Kitazawa, we discuss bi-local string states as a tool for loop computations in noncommutative field theory and matrix models. Defined in terms of coherent states, they exhibit the stringy features of noncommutative field theory. This leads to a closed form for the 1-loop effective action in position space, capturing the long-range non-local UV/IR mixing for scalar fields. The formalism applies to generic fuzzy spaces. The non-locality is tamed in the maximally supersymmetric IKKT or IIB model, where it gives rise to supergravity. The linearized supergravity interactions are obtained directly in position space at one loop using string states on generic noncommutative branes.

  9. Superfield formalism for the one loop effective action and CP(N) model in three dimensions

    International Nuclear Information System (INIS)

    Cho, Jin-Ho; Hahn, Sang-Ok; Oh, Phillial; Park, Cheonsoo; Park, Jeong-Hyuck

    2004-01-01

    To obtain the one loop effective action for a given superfield theory, one encounters the notion such as the 'super trace' of a differential operator on superspace. We develop, in a systematic way for the superspace of arbitrary dimension, a method to determine the super trace precisely. We present a formula to express the super trace explicitly as the superspace integral, which enables us to write the one loop effective action within the superfield formalism and still maintain the manifest supersymmetry. In the second part of the paper, we apply the result to a three dimensional N=1 supersymmetric CP(N) model in the auxiliary superfield formalism. The model contains a novel topological interaction term. We show in the large N limit the one loop effective action is given by the supersymmetric Maxwell-Chern-Simons theory. (author)

  10. [The relationship of Campylobacter jejuni subsp. jejuni enterotoxigenicity and the increase of cAMP and electrolyte changes in the rat intestine].

    Science.gov (United States)

    Fernández, H; Toro, J

    1998-08-01

    Small intestine alterations produced by the enterotoxigenic capacity of Campylobacter jejuni subsp. jejuni are similar to the hydric, electrolytic and pathological changes caused by choleraic and thermolabile Escherichia coli toxins. To study the enterotoxigenic capacity of 4 strains of Campylobacter jejuni subsp. jejuni using the intestinal loop model. Rat intestinal loops were inoculated with culture filtrates of the four strains. Enterotoxigenicity was assessed by fluid accumulation, the increase in Na+ and Cl- in the loop fluid, and cAMP increase in loop tissues. An enterotoxigenic Escherichia coil strain and sterile Brucella both were used as positive and negative controls, respectively. The filtrates of two strains produced fluid accumulation in the loops, significantly increased Na+ and Cl- secretion to the intestinal lumen and increased tissue cAMP levels. Some strains of Campylobacter jejuni subsp. jejuni are able to show enterotoxigenicity in vivo, increasing cAMP levels in the intestinal cells and altering electrolyte exchange mechanisms.

  11. A Simple Model for the Evolution of Multi-Stranded Coronal Loops

    Science.gov (United States)

    Fuentes, M. C. Lopez; Klimchuk, J. A.

    2010-01-01

    We develop and analyze a simple cellular automaton (CA) model that reproduces the main properties of the evolution of soft X-ray coronal loops. We are motivated by the observation that these loops evolve in three distinguishable phases that suggest the development, maintainance, and decay of a self-organized system. The model is based on the idea that loops are made of elemental strands that are heated by the relaxation of magnetic stress in the form of nanoflares. In this vision, usually called "the Parker conjecture" (Parker 1988), the origin of stress is the displacement of the strand footpoints due to photospheric convective motions. Modeling the response and evolution of the plasma we obtain synthetic light curves that have the same characteristic properties (intensity, fluctuations, and timescales) as the observed cases. We study the dependence of these properties on the model parameters and find scaling laws that can be used as observational predictions of the model. We discuss the implications of our results for the interpretation of recent loop observations in different wavelengths. Subject headings: Sun: corona - Sun: flares - Sun: magnetic topology - Sun: X-rays, gamma rays

  12. The Life Cycle Evaluation Model of External Diseconomy of Open-loop Supply Chain

    Science.gov (United States)

    Liu, Qian; Hu, Tianjun

    2017-08-01

    In recent years, with the continuous deterioration of pollution, resource space is gradually narrowed, the number of waste items increased, people began to use the method of recycling on waste products to ease the pressure on the environment. This paper adopted the external diseconomy of open-loop supply chain as the research object and constructed the model by the life cycle evaluation method, comparative analysis through the case. This paper also concludes that the key to solving the problem is to realize the closed-loop supply chain and building reverse logistics system is of great significance.

  13. A closed-loop power controller model of series-resonant-inverter-fitted induction heating system

    Directory of Open Access Journals (Sweden)

    Pal Palash

    2016-12-01

    Full Text Available This paper presents a mathematical model of a power controller for a high-frequency induction heating system based on a modified half-bridge series resonant inverter. The output real power is precise over the heating coil, and this real power is processed as a feedback signal that contends a closed-loop topology with a proportional-integral-derivative controller. This technique enables both control of the closed-loop power and determination of the stability of the high-frequency inverter. Unlike the topologies of existing power controllers, the proposed topology enables direct control of the real power of the high-frequency inverter.

  14. Two-loop beta-functions of the sine-Gordon model

    Science.gov (United States)

    Balog, János; Hegedus, Árpád

    2000-09-01

    We recalculate the two-loop beta-functions in the two-dimensional sine-Gordon model in a two-parameter expansion around the asymptotically free point. Our results agree with those of Amit et al (Amit D J, Goldschmidt Y Y and Grinstein G 1980 J. Phys. A: Math. Gen. 13 585).

  15. Model Optimization Identification Method Based on Closed-loop Operation Data and Process Characteristics Parameters

    Directory of Open Access Journals (Sweden)

    Zhiqiang GENG

    2014-01-01

    Full Text Available Output noise is strongly related to input in closed-loop control system, which makes model identification of closed-loop difficult, even unidentified in practice. The forward channel model is chosen to isolate disturbance from the output noise to input, and identified by optimization the dynamic characteristics of the process based on closed-loop operation data. The characteristics parameters of the process, such as dead time and time constant, are calculated and estimated based on the PI/PID controller parameters and closed-loop process input/output data. And those characteristics parameters are adopted to define the search space of the optimization identification algorithm. PSO-SQP optimization algorithm is applied to integrate the global search ability of PSO with the local search ability of SQP to identify the model parameters of forward channel. The validity of proposed method has been verified by the simulation. The practicability is checked with the PI/PID controller parameter turning based on identified forward channel model.

  16. Higgs Decay to Two Photons at One Loop in the Standard Model Effective Field Theory.

    Science.gov (United States)

    Hartmann, Christine; Trott, Michael

    2015-11-06

    We present the calculation of the CP conserving contributions to Γ(h→γγ), from dimension six operators at one-loop order, in the linear standard model effective field theory. We discuss the impact of these corrections on interpreting current and future experimental bounds on this decay.

  17. Modelling and analysis of an open-loop induction motor drive ...

    Indian Academy of Sciences (India)

    ... study the influence of inverter dead-time on steady as well as dynamic operation of an open-loop induction motor drive fed from a voltage source inverter (VSI). Towards this goal, this paper presents a systematic derivation of a dynamic model for an inverter-fed induction motor, incorporating the effect of inverter dead-time, ...

  18. Computer studies on dynamics of a large-scale magnetic loop by the spontaneous fast reconnection model

    Science.gov (United States)

    Ugai, M.

    1996-11-01

    The temporal dynamics of a large-scale magnetic loop is numerically studied on the basis of the two-dimensional spontaneous fast reconnection model. When a plasmoid, caused by the fast reconnection, propagates and collides with a wall boundary, across which plasma cannot flow, a large-scale magnetic loop is formed. The resulting magnetic loop is constructed by the reconnected field lines; inside the loop, the plasma, initially residing in the current sheet, is confined. As the reconnected field lines are piled up, the magnetic loop grows and swells outwards, so that a strong fast shock suddenly builds up at the interface between the growing loop and the strong reconnection jet. The fast shock, located ahead of the loop top, moves outwards with the growing loop, changing its strength with several peak and bottom Mach numbers. Accordingly, a localized spot-like region, where the plasma pressure is extremely enhanced, definitely comes out immediately ahead of the loop top. Along the loop side boundary, slow shocks stand, so that the resulting large-scale magnetic loop provides a very powerful energy converter in the sense that it is enclosed by slow and fast shocks.

  19. Hysteresis loop signatures of phase transitions in a mean-field model of disordered Ising magnet

    Science.gov (United States)

    Timonin, P. N.

    2010-06-01

    The multiplicity of long-lived states in frustrated disordered magnets makes the task to experimentally deter-mine which of them has the lowest free energy (and thus what thermodynamic phase the sample is in) seem rather hopeless. Nevertheless here we show in the framework of Landau-type phenomenological model that signatures of the mean-field equilibrium phase transitions in such highly nonequilibrium systems may be found in the evolution of the hysteresis loop form. Thus the sequence of transitions from spin-glass to mixed phase and to ferromagnetic one results in the changes from inclined hysteresis loop to that with the developing vertical sides and to one with the perfectly vertical sides. Such relation between loop form and the location of global minimum may hold beyond the mean-field approximation and can be useful in the real experiments and Monte-Carlo simulations of the problems involving rugged potential landscape.

  20. One-loop contributions to neutral minima in the inert doublet model

    International Nuclear Information System (INIS)

    Ferreira, P.M.; Świeżewska, Bogumiła

    2016-01-01

    The vacuum structure of the inert doublet model is analysed at the one-loop level using the effective potential formalism, to verify the validity of tree-level predictions for the properties of the global minimum. An inert minimum (with massive fermions) and an inert-like minimum (with massless fermions) can coexist at tree level. But the one-loop analysis reveals that the allowed parameter space for the coexistence of more than one minimum is larger than the tree-level expected one. It is also shown that for some choices of parameters, the global minimum found at the one-loop level may be inert (or inert-like), contrary to what the tree-level analysis indicates.

  1. Genetic Factors in Animal Models of Intestinal Inflammation

    Directory of Open Access Journals (Sweden)

    R Balfour Sartor

    1995-01-01

    Full Text Available The critical importance of host genetic susceptibility in determining chronicity, aggressiveness and complications of intestinal inflammation is clearly demonstrated by studies of inbred rodents, transgenic rats and spontaneous mutants. Inbred Lewis rats challenged by purified bacterial cell wall polymers, indomethacin or small bowel bacterial overgrowth develop chronic granulomatous intestinal inflammation with fibrosis and extraintestinal manifestations, whereas Fischer (major histocompatibility complex identical to Lewis and Buffalo rats identically stimulated demonstrate only self-limited enterocolitis with no chronic inflammation, fibrosis, granulomas or extraintestinal inflammation. Similar differential patterns of intestinal inflammation are apparent in inbred mouse strains challenged with trinitrobenzene-sulphonic acid, Citrobacter freundii or backcrossed with T cell receptor deficient (knockout mice. The dominant role of genetic background in induction of intestinal inflammation is further documented by spontaneous colitis which develops in spontaneously mutant mice, cotton-top tamarins, human leukocyte antigen-B27/ β2 microglobulin transgenic rats and mice with targeted deletions of certain immunoregulatory cytokine and T lymphocyte genes. Identification of the immunological mechanisms of host genetic susceptibility and the genetic basis of spontaneous colitis should provide new insights into the pathogenesis of human inflammatory bowel disease.

  2. In Silico Modelling of the Human Intestinal Microflora

    NARCIS (Netherlands)

    Kamerman, Derk Jan; Wilkinson, Michael H.F.

    2002-01-01

    The ecology of the human intestinal microflora and its interaction with the host are poorly understood. Though more and more data are being acquired, in part using modern molecular methods, development of a quantitative theory has not kept pace with this development. This is in part due to the

  3. Effects of synbiotics on intestinal mucosal barrier in rat model

    Directory of Open Access Journals (Sweden)

    Zhigang Xue

    2017-06-01

    Conclusions: Probiotics can improve the concentration of colonic probiotics, while synbiotics can improve probiotics concentration and mucosa thickness in colon, decrease L/M ratio and bacterial translocation. Synbiotics shows more protective effects on intestinal mucosal barrier in rats after cecectomy and gastrostomy and the intervention of specific antibiotics.

  4. A genetically inducible porcine model of intestinal cancer

    DEFF Research Database (Denmark)

    Callesen, Morten M.; Árnadóttir, Sigrid S.; Lyskjær, Iben

    2017-01-01

    of intestinal cancer. Transgenic (TG) minipigs were generated using somatic cell nuclear transfer by handmade cloning. The pigs encode two TG cassettes: (a) an Flp recombinase-inducible oncogene cassette containing KRAS-G12D, cMYC, SV40LT - which inhibits p53 - and pRB and (b) a 4-hydroxytamoxifen (4-OHT...

  5. Glutamate prevents intestinal atrophy via luminal nutrient sensing in a mouse model of total parenteral nutrition

    DEFF Research Database (Denmark)

    Xiao, Weidong; Feng, Yongjia; Holst, Jens Juul

    2014-01-01

    Small intestine luminal nutrient sensing may be crucial for modulating physiological functions. However, its mechanism of action is incompletely understood. We used a model of enteral nutrient deprivation, or total parenteral nutrition (TPN), resulting in intestinal mucosal atrophy and decreased...... was regulated by T1R3 and mGluR5, suggesting a novel negative regulator pathway for IEC proliferation not previously described. Loss of luminal nutrients with TPN administration may widely affect intestinal taste sensing. GLM has previously unrecognized actions on IEC growth and EBF. Restoring luminal sensing...

  6. A hysteresis model for ferroelectric ceramics with mechanism for minor loops

    International Nuclear Information System (INIS)

    Wang, Dan; Wang, Linxiang; Melnik, Roderick

    2017-01-01

    In the current paper, the coupled hysteretic behaviors of ferroelectric ceramics subjected to combined electromechanical stimulations are modeled. For a single grain, the polarization orientation switching process is modeled by employing the Euler–Lagrange equations and formulated as a coupled differential equation system. For ferroelectric ceramics, the principle axis orientations of the individual grains are assumed to be distributed in a certain profile, the behaviors of the ceramics are modeled as a weighted combination of the response of each grain. The influence of intergranular interactions is carefully discussed. Numerical results for the minor hysteresis loops in strain and polarization are demonstrated. Comparisons between these results and their experimental counterparts are presented to illustrate the attributes of the proposed model. - Highlights: • Coupled hysteresis in ferroelectric ceramics is efficiently captured. • Intergranular interactions are naturally incorporated into the model. • Mechanism for minor loops generation is well illustrated.

  7. A hysteresis model for ferroelectric ceramics with mechanism for minor loops

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Dan [State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, 310027 Hangzhou (China); MS2Discovery Interdisciplinary Research Institute, Wilfrid Laurier University, Waterloo, ON N2L 3L5 (Canada); Wang, Linxiang, E-mail: wanglx236@zju.edu.cn [State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, 310027 Hangzhou (China); Melnik, Roderick [MS2Discovery Interdisciplinary Research Institute, Wilfrid Laurier University, Waterloo, ON N2L 3L5 (Canada)

    2017-01-30

    In the current paper, the coupled hysteretic behaviors of ferroelectric ceramics subjected to combined electromechanical stimulations are modeled. For a single grain, the polarization orientation switching process is modeled by employing the Euler–Lagrange equations and formulated as a coupled differential equation system. For ferroelectric ceramics, the principle axis orientations of the individual grains are assumed to be distributed in a certain profile, the behaviors of the ceramics are modeled as a weighted combination of the response of each grain. The influence of intergranular interactions is carefully discussed. Numerical results for the minor hysteresis loops in strain and polarization are demonstrated. Comparisons between these results and their experimental counterparts are presented to illustrate the attributes of the proposed model. - Highlights: • Coupled hysteresis in ferroelectric ceramics is efficiently captured. • Intergranular interactions are naturally incorporated into the model. • Mechanism for minor loops generation is well illustrated.

  8. Structure-Function Model for Kissing Loop Interactions That Initiate Dimerization of Ty1 RNA.

    Science.gov (United States)

    Gamache, Eric R; Doh, Jung H; Ritz, Justin; Laederach, Alain; Bellaousov, Stanislav; Mathews, David H; Curcio, M Joan

    2017-04-26

    The genomic RNA of the retrotransposon Ty1 is packaged as a dimer into virus-like particles. The 5' terminus of Ty1 RNA harbors cis -acting sequences required for translation initiation, packaging and initiation of reverse transcription (TIPIRT). To identify RNA motifs involved in dimerization and packaging, a structural model of the TIPIRT domain in vitro was developed from single-nucleotide resolution RNA structural data. In general agreement with previous models, the first 326 nucleotides of Ty1 RNA form a pseudoknot with a 7-bp stem (S1), a 1-nucleotide interhelical loop and an 8-bp stem (S2) that delineate two long, structured loops. Nucleotide substitutions that disrupt either pseudoknot stem greatly reduced helper-Ty1-mediated retrotransposition of a mini-Ty1, but only mutations in S2 destabilized mini-Ty1 RNA in cis and helper-Ty1 RNA in trans. Nested in different loops of the pseudoknot are two hairpins with complementary 7-nucleotide motifs at their apices. Nucleotide substitutions in either motif also reduced retrotransposition and destabilized mini- and helper-Ty1 RNA. Compensatory mutations that restore base-pairing in the S2 stem or between the hairpins rescued retrotransposition and RNA stability in cis and trans. These data inform a model whereby a Ty1 RNA kissing complex with two intermolecular kissing-loop interactions initiates dimerization and packaging.

  9. Structure-Function Model for Kissing Loop Interactions That Initiate Dimerization of Ty1 RNA

    Directory of Open Access Journals (Sweden)

    Eric R. Gamache

    2017-04-01

    Full Text Available The genomic RNA of the retrotransposon Ty1 is packaged as a dimer into virus-like particles. The 5′ terminus of Ty1 RNA harbors cis-acting sequences required for translation initiation, packaging and initiation of reverse transcription (TIPIRT. To identify RNA motifs involved in dimerization and packaging, a structural model of the TIPIRT domain in vitro was developed from single-nucleotide resolution RNA structural data. In general agreement with previous models, the first 326 nucleotides of Ty1 RNA form a pseudoknot with a 7-bp stem (S1, a 1-nucleotide interhelical loop and an 8-bp stem (S2 that delineate two long, structured loops. Nucleotide substitutions that disrupt either pseudoknot stem greatly reduced helper-Ty1-mediated retrotransposition of a mini-Ty1, but only mutations in S2 destabilized mini-Ty1 RNA in cis and helper-Ty1 RNA in trans. Nested in different loops of the pseudoknot are two hairpins with complementary 7-nucleotide motifs at their apices. Nucleotide substitutions in either motif also reduced retrotransposition and destabilized mini- and helper-Ty1 RNA. Compensatory mutations that restore base-pairing in the S2 stem or between the hairpins rescued retrotransposition and RNA stability in cis and trans. These data inform a model whereby a Ty1 RNA kissing complex with two intermolecular kissing-loop interactions initiates dimerization and packaging.

  10. All-trans-retinoic acid attenuates intestinal injury in a neonatal rat model of necrotizing enterocolitis.

    Science.gov (United States)

    Ozdemir, Ramazan; Yurttutan, Sadık; Sari, Fatma Nur; Oncel, Mehmet Yekta; Erdeve, Omer; Unverdi, Hatice Germen; Uysal, Bülent; Dilmen, Ugur

    2013-01-01

    Ischemia/reperfusion-induced intestinal injury is mediated by reactive oxygen species and inflammatory mediators. This study was designed to evaluate whether all-trans-retinoic acid (ATRA) administration can attenuate intestinal injury and to analyze the antioxidant and anti-inflammatory effects of ATRA in a neonatal rat model of necrotizing enterocolitis (NEC). Twenty-nine Wistar albino rat pups were randomly divided into 3 groups: group 1 = control, group 2 = NEC and saline, and group 3 = NEC and ATRA treatment. NEC was induced by hyperosmolar enteral formula feeding and exposure to hypoxia after cold stress at +4°C and oxygen. Pups in group 3 were injected intraperitoneally with ATRA (0.5 mg/kg body weight) once a day prior to each NEC procedure, beginning on postnatal day 1 and daily through postnatal day 4. The pups were killed on the 4th day and their intestinal tissues were harvested for biochemical and histopathological analysis. Mucosal injury scores and intestinal malondialdehyde levels in group 2 were found to be significantly higher than other groups (p Intestinal superoxide dismutase and glutathione peroxidase activities in group 3 were significantly higher than group 2 (p = 0.04 and p = 0.04, respectively). Intestinal tissue tumor necrosis factor-α levels were significantly reduced with ATRA treatment in group 3 compared to group 2 (p intestinal injury through its anti-inflammatory and antioxidant properties. Copyright © 2013 S. Karger AG, Basel.

  11. Artificial neural network models for prediction of intestinal permeability of oligopeptides

    Directory of Open Access Journals (Sweden)

    Kim Min-Kook

    2007-07-01

    Full Text Available Abstract Background Oral delivery is a highly desirable property for candidate drugs under development. Computational modeling could provide a quick and inexpensive way to assess the intestinal permeability of a molecule. Although there have been several studies aimed at predicting the intestinal absorption of chemical compounds, there have been no attempts to predict intestinal permeability on the basis of peptide sequence information. To develop models for predicting the intestinal permeability of peptides, we adopted an artificial neural network as a machine-learning algorithm. The positive control data consisted of intestinal barrier-permeable peptides obtained by the peroral phage display technique, and the negative control data were prepared from random sequences. Results The capacity of our models to make appropriate predictions was validated by statistical indicators including sensitivity, specificity, enrichment curve, and the area under the receiver operating characteristic (ROC curve (the ROC score. The training and test set statistics indicated that our models were of strikingly good quality and could discriminate between permeable and random sequences with a high level of confidence. Conclusion We developed artificial neural network models to predict the intestinal permeabilities of oligopeptides on the basis of peptide sequence information. Both binary and VHSE (principal components score Vectors of Hydrophobic, Steric and Electronic properties descriptors produced statistically significant training models; the models with simple neural network architectures showed slightly greater predictive power than those with complex ones. We anticipate that our models will be applicable to the selection of intestinal barrier-permeable peptides for generating peptide drugs or peptidomimetics.

  12. Challenges in LCA modelling of multiple loops for aluminium cans

    OpenAIRE

    Niero, Monia; Olsen, Stig Irving

    2016-01-01

    Life Cycle Assessment (LCA) has traditionally played a key role in identifying the most efficient envi- ronmental design strategies and the best option for the end-of-life of products from an environmental point of view, within “one life cycle” approach. However, such an approach fails to capture one of themain features of circular product systems, i.e. the need to model multiple life cycles. There are some key methodological challenges that LCA has to face in order to exploit its potential i...

  13. Intestinal ischemia-reperfusion induced diaphragm contractility dysfunction: Electrophysiological and ultrastructural study in a neonatal rat model.

    Science.gov (United States)

    Taşkınlar, Hakan; Naycı, Ali; Çömelekoğlu, Ülkü; Polat, Gürbüz; Zorludemir, Suzan; Avlan, Dinçer

    2016-03-01

    To evaluate the remote effect of intestinal ischemia reperfusion (IR) injury mediated by tumor necrosis factor alpha (TNF-α) on diaphragm contractility functions and whether administration of NAC may counteract the possible detrimental effects in an experimental neonatal rat model. 40 Wistar rat pups were randomized into four groups; ten animals in each. Intestinal ischemia was conducted by obstructing mesentery of intestines by a silk loop. In the control group; only laparotomy was performed. After 1h ischemia, reperfusion was conducted for 1h in 1h group, 24h for 24h group and 24h for 24h+NAC group but administration of NAC (150mg/kg/day) intraperitoneally twice a day was performed. Inflammatory response was evaluated by tissue TNF-α level and contractility functions by mechanic activity studies of the diaphragm. Electrophysiology of the diaphragm and the phrenic nerve was conducted to determine neuropathy or myopathy and transmission electron microscopy was performed to evaluate ultrastructural changes in the phrenic nerve. Diaphragm tissue TNF-α level significantly increased in 1h and 24h groups (P=0.004, P=0.0001; respectively). Diaphragm mechanic activation force and duration significantly decreased at 1h and 24h (P=0.004, P=0.02 and P=0.0001, P=0.0001; respectively). NAC administration significantly prevented decrease in the maximal contraction and the duration (PIntestinal IR induced elevation of TNF-α level in the diaphragm. Impairment in the diaphragm contractility and neuropathic changes in the phrenic nerve occurred even in the first hour of reperfusion. NAC administration prevented these detrimental effects. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Four loop wave function renormalization in the non-abelian Thirring model

    International Nuclear Information System (INIS)

    Ali, D.B.; Gracey, J.A.

    2001-01-01

    We compute the anomalous dimension of the fermion field with N f flavours in the fundamental representation of a general Lie colour group in the non-abelian Thirring model at four loops. The implications on the renormalization of the two point Green's function through the loss of multiplicative renormalizability of the model in dimensional regularization due to the appearance of evanescent four fermi operators are considered at length. We observe the appearance of one new colour group Casimir, d F abcd d F abcd , in the final four loop result and discuss its consequences for the relation of the Knizhnik-Zamolodchikov critical exponents in the Wess-Zumino-Witten-Novikov model to the non-abelian Thirring model. Renormalization scheme changes are also considered to ensure that the underlying Fierz symmetry broken by dimensional regularization is restored

  15. Development of a transient calculation model for a closed sodium natural circulation loop

    International Nuclear Information System (INIS)

    Chang, Won Pyo; Ha, Kwi Seok; Jeong, Hae Yong; Heo, Sun; Lee, Yong Bum

    2003-09-01

    A natural circulation loop has usually adopted for a Liquid Metal Reactor (LMR) because of its high reliability. Up-rating of the current KALIMER capacity requires an additional PDRC to the existing PVCS to remove its decay heat under an accident. As the system analysis code currently used for LMR in Korea does not feature a stand alone capability to simulate a closed natural circulation loop, it is not eligible to be applied to PDRC. To supplement its limitation, a steady state calculation model had been developed during the first phase, and development of the transient model has successively carried out to close the present study. The developed model will then be coupled with the system analysis code, SSC-K to assess a long term cooling for the new conceptual design. The incompressibility assumption of sodium which allows the circuit to be modeled with a single loop flow, makes the model greatly simplified comparing with LWR. Some thermal-hydraulic models developed during this study can be effectively applied to other system analysis codes which require such component models, and the present development will also contribute to establishment of a code system for the LMR analysis

  16. Two-loop renormalization in the standard model, part II. Renormalization procedures and computational techniques

    Energy Technology Data Exchange (ETDEWEB)

    Actis, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Passarino, G. [Torino Univ. (Italy). Dipt. di Fisica Teorica; INFN, Sezione di Torino (Italy)

    2006-12-15

    In part I general aspects of the renormalization of a spontaneously broken gauge theory have been introduced. Here, in part II, two-loop renormalization is introduced and discussed within the context of the minimal Standard Model. Therefore, this paper deals with the transition between bare parameters and fields to renormalized ones. The full list of one- and two-loop counterterms is shown and it is proven that, by a suitable extension of the formalism already introduced at the one-loop level, two-point functions suffice in renormalizing the model. The problem of overlapping ultraviolet divergencies is analyzed and it is shown that all counterterms are local and of polynomial nature. The original program of 't Hooft and Veltman is at work. Finite parts are written in a way that allows for a fast and reliable numerical integration with all collinear logarithms extracted analytically. Finite renormalization, the transition between renormalized parameters and physical (pseudo-)observables, are discussed in part III where numerical results, e.g. for the complex poles of the unstable gauge bosons, are shown. An attempt is made to define the running of the electromagnetic coupling constant at the two-loop level. (orig.)

  17. Model-based minimization algorithm of a supercritical helium loop consumption subject to operational constraints

    Science.gov (United States)

    Bonne, F.; Bonnay, P.; Girard, A.; Hoa, C.; Lacroix, B.; Le Coz, Q.; Nicollet, S.; Poncet, J.-M.; Zani, L.

    2017-12-01

    Supercritical helium loops at 4.2 K are the baseline cooling strategy of tokamaks superconducting magnets (JT-60SA, ITER, DEMO, etc.). This loops work with cryogenic circulators that force a supercritical helium flow through the superconducting magnets in order that the temperature stay below the working range all along their length. This paper shows that a supercritical helium loop associated with a saturated liquid helium bath can satisfy temperature constraints in different ways (playing on bath temperature and on the supercritical flow), but that only one is optimal from an energy point of view (every Watt consumed at 4.2 K consumes at least 220 W of electrical power). To find the optimal operational conditions, an algorithm capable of minimizing an objective function (energy consumption at 5 bar, 5 K) subject to constraints has been written. This algorithm works with a supercritical loop model realized with the Simcryogenics [2] library. This article describes the model used and the results of constrained optimization. It will be possible to see that the changes in operating point on the temperature of the magnet (e.g. in case of a change in the plasma configuration) involves large changes on the cryodistribution optimal operating point. Recommendations will be made to ensure that the energetic consumption is kept as low as possible despite the changing operating point. This work is partially supported by EUROfusion Consortium through the Euratom Research and Training Program 20142018 under Grant 633053.

  18. One-loop beta functions for the orientable non-commutative Gross Neveu model TH1"-->

    Science.gov (United States)

    Lakhoua, A.; Vignes-Tourneret, F.; Wallet, J.-C.

    2007-11-01

    We compute at the one-loop order the β-functions for a renormalisable non-commutative analog of the Gross Neveu model defined on the Moyal plane. The calculation is performed within the so called x-space formalism. We find that this non-commutative field theory exhibits asymptotic freedom for any number of colors. The β-function for the non-commutative counterpart of the Thirring model is found to be non vanishing.

  19. Looping and clustering model for the organization of protein-DNA complexes on the bacterial genome

    Science.gov (United States)

    Walter, Jean-Charles; Walliser, Nils-Ole; David, Gabriel; Dorignac, Jérôme; Geniet, Frédéric; Palmeri, John; Parmeggiani, Andrea; Wingreen, Ned S.; Broedersz, Chase P.

    2018-03-01

    The bacterial genome is organized by a variety of associated proteins inside a structure called the nucleoid. These proteins can form complexes on DNA that play a central role in various biological processes, including chromosome segregation. A prominent example is the large ParB-DNA complex, which forms an essential component of the segregation machinery in many bacteria. ChIP-Seq experiments show that ParB proteins localize around centromere-like parS sites on the DNA to which ParB binds specifically, and spreads from there over large sections of the chromosome. Recent theoretical and experimental studies suggest that DNA-bound ParB proteins can interact with each other to condense into a coherent 3D complex on the DNA. However, the structural organization of this protein-DNA complex remains unclear, and a predictive quantitative theory for the distribution of ParB proteins on DNA is lacking. Here, we propose the looping and clustering model, which employs a statistical physics approach to describe protein-DNA complexes. The looping and clustering model accounts for the extrusion of DNA loops from a cluster of interacting DNA-bound proteins that is organized around a single high-affinity binding site. Conceptually, the structure of the protein-DNA complex is determined by a competition between attractive protein interactions and loop closure entropy of this protein-DNA cluster on the one hand, and the positional entropy for placing loops within the cluster on the other. Indeed, we show that the protein interaction strength determines the ‘tightness’ of the loopy protein-DNA complex. Thus, our model provides a theoretical framework for quantitatively computing the binding profiles of ParB-like proteins around a cognate (parS) binding site.

  20. All-loop renormalizable Wess-Zumino model on bosonic-fermionic noncommutative superspace

    Science.gov (United States)

    Miao, Yan-Gang; Wang, Xu-Dong

    2015-01-01

    We generalize the ordinary Wess-Zumino model to the bosonic-fermionic noncommutative (BFNC) superspace and study its renormalization. In our previous work that can be regarded as the key foundation of the present paper, we have proved that the BFNC Wess-Zumino model with the real mass and interacting constant is one-loop renormalizable up to the second order of BFNC parameters. Based on the result obtained, in the present paper we modify the one-loop renormalizable BFNC Wess-Zumino model by generalizing the mass and interacting constant to complex numbers, introduce the U (1 )R R symmetry and U (1 )Φ flavor symmetry in the modified model, analyze possible divergent operators in the effective action of the modified model by using the dimensional analysis method, and further give a new BFNC Wess-Zumino model that is renormalizable at all loops still up to the second order of BFNC parameters by imposing symmetries rather than doing a direct perturbative investigation.

  1. Intestinal Stem Cell Niche Insights Gathered from Both In Vivo and Novel In Vitro Models

    Directory of Open Access Journals (Sweden)

    Nikolce Gjorevski

    2017-01-01

    Full Text Available Intestinal stem cells are located at the base of the crypts and are surrounded by a complex structure called niche. This environment is composed mainly of epithelial cells and stroma which provides signals that govern cell maintenance, proliferation, and differentiation. Understanding how the niche regulates stem cell fate by controlling developmental signaling pathways will help us to define how stem cells choose between self-renewal and differentiation and how they maintain their undifferentiated state. Tractable in vitro assay systems, which reflect the complexity of the in vivo situation but provide higher level of control, would likely be crucial in identifying new players and mechanisms controlling stem cell function. Knowledge of the intestinal stem cell niche gathered from both in vivo and novel in vitro models may help us improve therapies for tumorigenesis and intestinal damage and make autologous intestinal transplants a feasible clinical practice.

  2. Combination of dehydroepiandrosterone and orthovanadate administration reduces intestinal leukocyte recruitment in models of experimental sepsis.

    Science.gov (United States)

    Al-Banna, Nadia; Pavlovic, Dragan; Sharawi, Nivin; Bac, Vo Hoai; Jaskulski, Mathis; Balzer, Claudius; Weber, Stefan; Nedeljkov, Vladimir; Lehmann, Christian

    2014-09-01

    Dehydroepiandrosterone (DHEA) was shown to improve the immune function and survival in experimental sepsis. This study examined the effect of DHEA on intestinal leukocyte recruitment during experimental sepsis, considering factors of gender (male, female and ovariectomized female animals) and combined treatment using orthovanadate (OV) in two models of sepsis. Male rats underwent colon ascendens stent peritonitis (CASP) or endotoxemia. DHEA was administered after induction of experimental sepsis. Changes in leukocyte adherence and capillary perfusion (measured as intestinal functional capillary density - FCD) were assessed using intravital microscopy. While DHEA increased baseline leukocyte adherence in control animals, DHEA reduced leukocyte adherence and increased FCD in male animals with CASP. These effects were also observed in DHEA-treated ovariectomized female rats with CASP. Similarly, the administration of DHEA reduced the number of adherent leukocytes to intestinal venules by 30% in the endotoxemia model. The combined treatment of DHEA and OV significantly reduced adherence of leukocytes to intestinal venules and improved FCD. Our results indicate that DHEA is able to reduce intestinal leukocyte recruitment induced by experimental sepsis. Combination of DHEA with OV inhibits leukocyte adherence to intestinal endothelium, similar to what is achieved by the single administration of DHEA but with significantly improved FCD. These findings suggest a potential role for DHEA and OV in clinical sepsis. Copyright © 2014 Elsevier Inc. All rights reserved.

  3. Naturally occurring glycoalkaloids in potatoes aggravate intestinal inflammation in two mouse models of inflammatory bowel disease.

    Science.gov (United States)

    Iablokov, Vadim; Sydora, Beate C; Foshaug, Rae; Meddings, Jon; Driedger, Darcy; Churchill, Tom; Fedorak, Richard N

    2010-11-01

    Inflammatory bowel disease (IBD) may be initiated following disruption of the intestinal epithelial barrier. This disruption, in turn, permits luminal antigens unfettered access to the mucosal immune system and leads to an uncontrolled inflammatory response. Glycoalkaloids, which are found in potatoes, disrupt cholesterol-containing membranes such as those of the intestinal epithelium. Glycoalkaloid ingestion through potatoes may play a role in the initiation and/or perpetuation of IBD. To determine if commercial and high glycoalkaloids containing fried potato skins aggravate intestinal inflammation using two different animal models of IBD. Fried potato skins from commercial potatoes containing low/medium glycoalkaloid levels and high glycoalkaloids potatoes were fed for 20 days to interleukin 10 gene-deficient mice and dextran sodium sulfate-induced colitic mice. Intestinal permeability, mucosal cytokine and myeloperoxidase levels and body weight were determined to assess intestinal injury. Deep frying potato skins markedly increased glycoalkaloid content. Interleukin 10 gene-deficient mice fed fried commercial potato skins with medium glycoalkaloid content exhibited significantly elevated levels of ileal IFN-γ relative to controls. Mice in the dextran sodium sulfate colitis model that were fed the same strain of potatoes demonstrated significantly elevated levels of pro-inflammatory cytokines IFN-γ, TNF-α, and IL-17 in the colon in addition to an enhanced colonic permeability. Inflammatory response was intensified when the mice were fed potatoes with higher glycoalkaloid contents. Our results demonstrate that consumption of potato skins containing glycoalkaloids can significantly aggravate intestinal inflammation in predisposed individuals.

  4. Intestinal tumorigenesis is not affected by progesterone signaling in rodent models.

    Directory of Open Access Journals (Sweden)

    Jarom Heijmans

    Full Text Available Clinical data suggest that progestins have chemopreventive properties in the development of colorectal cancer. We set out to examine a potential protective effect of progestins and progesterone signaling on colon cancer development. In normal and neoplastic intestinal tissue, we found that the progesterone receptor (PR is not expressed. Expression was confined to sporadic mesenchymal cells. To analyze the influence of systemic progesterone receptor signaling, we crossed mice that lacked the progesterone receptor (PRKO to the Apc(Min/+ mouse, a model for spontaneous intestinal polyposis. PRKO-Apc(Min/+ mice exhibited no change in polyp number, size or localization compared to Apc(Min/+. To examine effects of progestins on the intestinal epithelium that are independent of the PR, we treated mice with MPA. We found no effects of either progesterone or MPA on gross intestinal morphology or epithelial proliferation. Also, in rats treated with MPA, injection with the carcinogen azoxymethane did not result in a difference in the number or size of aberrant crypt foci, a surrogate end-point for adenoma development. We conclude that expression of the progesterone receptor is limited to cells in the intestinal mesenchyme. We did not observe any effect of progesterone receptor signaling or of progestin treatment in rodent models of intestinal tumorigenesis.

  5. Object-oriented modeling and simulation of the closed loop cardiovascular system by using SIMSCAPE.

    Science.gov (United States)

    de Canete, J Fernandez; del Saz-Orozco, P; Moreno-Boza, D; Duran-Venegas, E

    2013-05-01

    The modeling of physiological systems via mathematical equations reflects the calculation procedure more than the structure of the real system modeled, with the simulation environment SIMULINK™ being one of the best suited to this strategy. Nevertheless, object-oriented modeling is spreading in current simulation environments through the use of the individual components of the model and its interconnections to define the underlying dynamic equations. In this paper we describe the use of the SIMSCAPE™ simulation environment in the object-oriented modeling of the closed loop cardiovascular system. The described approach represents a valuable tool in the teaching of physiology for graduate medical students. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. The Sustainability Cycle and Loop: models for a more unified understanding of sustainability.

    Science.gov (United States)

    Hay, Laura; Duffy, Alex; Whitfield, R I

    2014-01-15

    In spite of the considerable research on sustainability, reports suggest that we are barely any closer to a more sustainable society. As such, there is an urgent need to improve the effectiveness of human efforts towards sustainability. A clearer and more unified understanding of sustainability among different people and sectors could help to facilitate this. This paper presents the results of an inductive literature investigation, aiming to develop models to explain the nature of sustainability in the Earth system, and how humans can effectively strive for it. The major contributions are two general and complementary models, that may be applied in any context to provide a common basis for understanding sustainability: the Sustainability Cycle (S-Cycle), and the Sustainability Loop (S-Loop). Literature spanning multiple sectors is examined from the perspective of three concepts, emerging as significant in relation to our aim. Systems are shown to provide the context for human action towards sustainability, and the nature of the Earth system and its sub-systems is explored. Activities are outlined as a fundamental target that humans need to sustain, since they produce the entities both needed and desired by society. The basic behaviour of activities operating in the Earth system is outlined. Finally, knowledge is positioned as the driver of human action towards sustainability, and the key components of knowledge involved are examined. The S-Cycle and S-Loop models are developed via a process of induction from the reviewed literature. The S-Cycle describes the operation of activities in a system from the perspective of sustainability. The sustainability of activities in a system depends upon the availability of resources, and the availability of resources depends upon the rate that activities consume and produce them. Humans may intervene in these dynamics via an iterative process of interpretation and action, described in the S-Loop model. The models are briefly

  7. Mathematical models and simulations of phase noise in phase-locked loops

    Directory of Open Access Journals (Sweden)

    Sethapong Limkumnerd

    2007-07-01

    Full Text Available Phase noises in Phase-Locked Loops (PLLs are a key parameter for communication systems that contribute the bit-rate-error of communication systems and cause synchronization problems. Accurate predictions of phase noises through mathematical models are consequently desirable for practical designs of PLLs. Despite many phase noise models derived from noise sources from electronic devices such as an oscillator and a multiplier have been proposed, no phase noise models that include noises from loop filters have specifically been investigated. This paper therefore investigates the roles of loop filters in phase noise contribution. The major scopes of this paper is a detailed analysis and simulations of phase noise models resulting from all components. i.e. a voltage-controlled oscillator, a multiplier and a filter. Two particular second-order passive and active low-pass filters are compared. The results show that simulations of phase noises without an inclusion of filter noises may not be accurate because the filter noises, particularly the active filter, significantly contribute the total phase noise. Moreover, the passive filter does not significantly dominate the phase noise at low offset frequency while the active filters entirely dominate. Therefore, the passive filter is a more efficient filter for PLL circuit at low offset frequency. The phase noise models presented in this paper are relatively simple and can be used for accurate phase noise prediction for PLL designs.

  8. Animal models of ischemia-reperfusion-induced intestinal injury: progress and promise for translational research

    Science.gov (United States)

    Gonzalez, Liara M.; Moeser, Adam J.

    2014-01-01

    Research in the field of ischemia-reperfusion injury continues to be plagued by the inability to translate research findings to clinically useful therapies. This may in part relate to the complexity of disease processes that result in intestinal ischemia but may also result from inappropriate research model selection. Research animal models have been integral to the study of ischemia-reperfusion-induced intestinal injury. However, the clinical conditions that compromise intestinal blood flow in clinical patients ranges widely from primary intestinal disease to processes secondary to distant organ failure and generalized systemic disease. Thus models that closely resemble human pathology in clinical conditions as disparate as volvulus, shock, and necrotizing enterocolitis are likely to give the greatest opportunity to understand mechanisms of ischemia that may ultimately translate to patient care. Furthermore, conditions that result in varying levels of ischemia may be further complicated by the reperfusion of blood to tissues that, in some cases, further exacerbates injury. This review assesses animal models of ischemia-reperfusion injury as well as the knowledge that has been derived from each to aid selection of appropriate research models. In addition, a discussion of the future of intestinal ischemia-reperfusion research is provided to place some context on the areas likely to provide the greatest benefit from continued research of ischemia-reperfusion injury. PMID:25414098

  9. Probing the closed-loop model of mRNA translation in living cells

    Science.gov (United States)

    Archer, Stuart K; Shirokikh, Nikolay E; Hallwirth, Claus V; Beilharz, Traude H; Preiss, Thomas

    2015-01-01

    The mRNA closed-loop, formed through interactions between the cap structure, poly(A) tail, eIF4E, eIF4G and PAB, features centrally in models of eukaryotic translation initiation, although direct support for its existence in vivo is not well established. Here, we investigated the closed-loop using a combination of mRNP isolation from rapidly cross-linked cells and high-throughput qPCR. Using the interaction between these factors and the opposing ends of mRNAs as a proxy for the closed-loop, we provide evidence that it is prevalent for eIF4E/4G-bound but unexpectedly sparse for PAB1-bound mRNAs, suggesting it primarily occurs during a distinct phase of polysome assembly. We observed mRNA-specific variation in the extent of closed-loop formation, consistent with a role for polysome topology in the control of gene expression. PMID:25826658

  10. A Derivation of the Long-Term Degradation of a Pulsed Atomic Frequency Standard from a Control-Loop Model

    Science.gov (United States)

    Greenhall, C. A.

    1996-01-01

    The phase of a frequency standard that uses periodic interrogation and control of a local oscillator (LO) is degraded by a long-term random-walk component induced by downconversion of LO noise into the loop passband. The Dick formula for the noise level of this degradation is derived from an explicit solution of an LO control-loop model.

  11. Dynamic modelling and PID loop control of an oil-injected screw compressor package

    Science.gov (United States)

    Poli, G. W.; Milligan, W. J.; McKenna, P.

    2017-08-01

    A significant amount of time is spent tuning the PID (Proportional, Integral and Derivative) control loops of a screw compressor package due to the unique characteristics of the system. Common mistakes incurred during the tuning of a PID control loop include improper PID algorithm selection and unsuitable tuning parameters of the system resulting in erratic and inefficient operation. This paper details the design and development of software that aims to dynamically model the operation of a single stage oil injected screw compressor package deployed in upstream oil and gas applications. The developed software will be used to assess and accurately tune PID control loops present on the screw compressor package employed in controlling the oil pressures, temperatures and gas pressures, in a bid to improve control of the operation of the screw compressor package. Other applications of the modelling software will include its use as an evaluation tool that can estimate compressor package performance during start up, shutdown and emergency shutdown processes. The paper first details the study into the fundamental operational characteristics of each of the components present on the API 619 screw compressor package and then discusses the creation of a dynamic screw compressor model within the MATLAB/Simulink software suite. The paper concludes by verifying and assessing the accuracy of the created compressor model using data collected from physical screw compressor packages.

  12. One-loop effects from spin-1 resonances in Composite Higgs models

    CERN Document Server

    Contino, Roberto

    2015-01-01

    We compute the 1-loop correction to the electroweak observables from spin-1 resonances in SO(5)/SO(4) composite Higgs models. The strong dynamics is modeled with an effective description comprising the Nambu-Goldstone bosons and the lowest-lying spin-1 resonances. A classification is performed of the relevant operators including custodially-breaking effects from the gauging of hypercharge. The 1-loop contribution of the resonances is extracted in a diagrammatic approach by matching to the low-energy theory of Nambu-Goldstone bosons. We find that the correction is numerically important in a significant fraction of the parameter space and tends to weaken the bounds providing a negative shift to the S parameter.

  13. Loop Quantization of Polarized Gowdy Model on $T^3$: Kinematical States and Constraint Operators

    OpenAIRE

    Banerjee, Kinjal; Date, Ghanashyam

    2007-01-01

    In this second paper on loop quantization of Gowdy model, we introduce the kinematical Hilbert space on which appropriate holonomies and fluxes are well represented. The quantization of the volume operator and the Gauss constraint is straightforward. Imposition of the Gauss constraint can be done on the kinematical Hilbert space to select subspace of gauge invariant states. We carry out the quantization of the Hamiltonian constraint making specific choices. Alternative choices are briefly dis...

  14. Modelling of Wheat-Flour Dough Mixing as an Open-Loop Hysteretic Process

    Czech Academy of Sciences Publication Activity Database

    Anderssen, R.; Kružík, Martin

    2013-01-01

    Roč. 18, č. 2 (2013), s. 283-293 ISSN 1531-3492 R&D Projects: GA AV ČR IAA100750802 Keywords : Dissipation * Dough mixing * Rate-independent systems Subject RIV: BA - General Mathematics Impact factor: 0.628, year: 2013 http://library.utia.cas.cz/separaty/2013/MTR/kruzik-modelling of wheat-flour dough mixing as an open-loop hysteretic process.pdf

  15. Loop-to-loop coupling.

    Energy Technology Data Exchange (ETDEWEB)

    Warne, Larry Kevin; Lucero, Larry Martin; Langston, William L.; Salazar, Robert Austin; Coleman, Phillip Dale; Basilio, Lorena I.; Bacon, Larry Donald

    2012-05-01

    This report estimates inductively-coupled energy to a low-impedance load in a loop-to-loop arrangement. Both analytical models and full-wave numerical simulations are used and the resulting fields, coupled powers and energies are compared. The energies are simply estimated from the coupled powers through approximations to the energy theorem. The transmitter loop is taken to be either a circular geometry or a rectangular-loop (stripline-type) geometry that was used in an experimental setup. Simple magnetic field models are constructed and used to estimate the mutual inductance to the receiving loop, which is taken to be circular with one or several turns. Circuit elements are estimated and used to determine the coupled current and power (an equivalent antenna picture is also given). These results are compared to an electromagnetic simulation of the transmitter geometry. Simple approximate relations are also given to estimate coupled energy from the power. The effect of additional loads in the form of attached leads, forming transmission lines, are considered. The results are summarized in a set of susceptibility-type curves. Finally, we also consider drives to the cables themselves and the resulting common-to-differential mode currents in the load.

  16. Modelling and simulation of a U-loop Reactor for Single Cell Protein Production

    DEFF Research Database (Denmark)

    Wu, Mengzhe; Huusom, Jakob Kjøbsted; Gernaey, Krist

    2016-01-01

    In this work, two approaches of modelling a one phase U-loop reactor are presented. A simple CSTR model consisting of first-principles dynamic process equations was implemented in Matlab. The results give a good indication of the basic understanding of the effect of changing operation conditions...... on process performance. For a given product yield, the work investigates how process parameters such as dilution rate (D) or the methanol concentration should be selected to optimize the production. Nevertheless, this simple model exhibits some limitations hindering the development of the optimal operation...

  17. Magnetization loop modelling for superconducting/ferromagnetic tube of an ac magnetic cloak

    International Nuclear Information System (INIS)

    Gömöry, F; Solovyov, M; Šouc, J

    2015-01-01

    From the combination of superconducting (SC) and ferromagnetic (FM) materials, one can prepare composites with unusual magnetic properties, e.g. for the cloaking of a dc or low-frequency ac magnetic field by a shell from a SC/FM composite. In the design and optimisation of such SC/FM structures, numerical modelling is essential. Non-linear magnetic permeability, as well as the hysteresis of both kinds of materials, are to be incorporated in the calculations aimed at achieving reliable estimates. We present a technique that allows the prediction of the ac magnetization loops of SC/FM composites. The critical state model-based approach is used to describe the properties of the superconducting material. The ferromagnetic part is characterized by its (non-hysteretic) nonlinear permeability. With these ingredients, the distributions of the magnetic field are calculated in subsequent instants of the ac cycle and are used to evaluate the preliminary data for the magnetization loop, which is still missing the hysteresis of the FM part. Afterward, the latter component is added to the magnetization loop by an approximation deduced from the known dependence of the hysteresis loss in the FM material on the ac magnetic field. In spite of its approximate nature, this approach demonstrated very good predictability in experimental tests. (paper)

  18. Two-loop renormalization in the standard model, part III. Renormalization equations and their solutions

    International Nuclear Information System (INIS)

    Actis, S.; Passarino, G.

    2006-12-01

    In part I and II of this series of papers all elements have been introduced to extend, to two loops, the set of renormalization procedures which are needed in describing the properties of a spontaneously broken gauge theory. In this paper, the final step is undertaken and finite renormalization is discussed. Two-loop renormalization equations are introduced and their solutions discussed within the context of the minimal standard model of fundamental interactions. These equations relate renormalized Lagrangian parameters (couplings and masses) to some input parameter set containing physical (pseudo-)observables. Complex poles for unstable gauge and Higgs bosons are used and a consistent setup is constructed for extending the predictivity of the theory from the Lep1 Z-boson scale (or the Lep2 WW scale) to regions of interest for LHC and ILC physics. (orig.)

  19. New Constraints on Dark Matter Effective Theories from Standard Model Loops

    CERN Document Server

    Crivellin, Andreas; Procura, Massimiliano

    2014-01-01

    We consider an effective field theory for a gauge singlet Dirac dark matter (DM) particle interacting with the Standard Model (SM) fields via effective operators suppressed by the scale $\\Lambda \\gtrsim 1$ TeV. We perform a systematic analysis of the leading loop contributions to spin-independent (SI) DM--nucleon scattering using renormalization group evolution between $\\Lambda$ and the low-energy scale probed by direct detection experiments. We find that electroweak interactions induce operator mixings such that operators that are naively velocity-suppressed and spin-dependent can actually contribute to SI scattering. This allows us to put novel constraints on Wilson coefficients that were so far poorly bounded by direct detection. Constraints from current searches are comparable to LHC bounds, and will significantly improve in the near future. Interestingly, the loop contribution we find is maximally isospin violating even if the underlying theory is isospin conserving.

  20. Two-loop renormalization in the standard model, part III. Renormalization equations and their solutions

    Energy Technology Data Exchange (ETDEWEB)

    Actis, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Passarino, G. [Torino Univ. (Italy). Dipt. di Fisica Teorica; INFN, Sezione di Torino (Italy)

    2006-12-15

    In part I and II of this series of papers all elements have been introduced to extend, to two loops, the set of renormalization procedures which are needed in describing the properties of a spontaneously broken gauge theory. In this paper, the final step is undertaken and finite renormalization is discussed. Two-loop renormalization equations are introduced and their solutions discussed within the context of the minimal standard model of fundamental interactions. These equations relate renormalized Lagrangian parameters (couplings and masses) to some input parameter set containing physical (pseudo-)observables. Complex poles for unstable gauge and Higgs bosons are used and a consistent setup is constructed for extending the predictivity of the theory from the Lep1 Z-boson scale (or the Lep2 WW scale) to regions of interest for LHC and ILC physics. (orig.)

  1. Analytical modeling provides new insight into complex mutual coupling between surface loops at ultrahigh fields.

    Science.gov (United States)

    Avdievich, N I; Pfrommer, A; Giapitzakis, I A; Henning, A

    2017-10-01

    Ultrahigh-field (UHF) (≥7 T) transmit (Tx) human head surface loop phased arrays improve both the Tx efficiency (B 1 + /√P) and homogeneity in comparison with single-channel quadrature Tx volume coils. For multi-channel arrays, decoupling becomes one of the major problems during the design process. Further insight into the coupling between array elements and its dependence on various factors can facilitate array development. The evaluation of the entire impedance matrix Z for an array loaded with a realistic voxel model or phantom is a time-consuming procedure when performed using electromagnetic (EM) solvers. This motivates the development of an analytical model, which could provide a quick assessment of the Z-matrix. In this work, an analytical model based on dyadic Green's functions was developed and validated using an EM solver and bench measurements. The model evaluates the complex coupling, including both the electric (mutual resistance) and magnetic (mutual inductance) coupling. Validation demonstrated that the model does well to describe the coupling at lower fields (≤3 T). At UHFs, the model also performs well for a practical case of low magnetic coupling. Based on the modeling, the geometry of a 400-MHz, two-loop transceiver array was optimized, such that, by simply overlapping the loops, both the mutual inductance and the mutual resistance were compensated at the same time. As a result, excellent decoupling (below -40 dB) was obtained without any additional decoupling circuits. An overlapped array prototype was compared (signal-to-noise ratio, Tx efficiency) favorably to a gapped array, a geometry which has been utilized previously in designs of UHF Tx arrays. Copyright © 2017 John Wiley & Sons, Ltd.

  2. Oregano Essential Oil Improves Intestinal Morphology and Expression of Tight Junction Proteins Associated with Modulation of Selected Intestinal Bacteria and Immune Status in a Pig Model

    Directory of Open Access Journals (Sweden)

    Yi Zou

    2016-01-01

    Full Text Available Oregano essential oil (OEO has long been used to improve the health of animals, particularly the health of intestine, which is generally attributed to its antimicrobial and anti-inflammatory effects. However, how OEO acts in the intestine of pig is still unclear. This study was aimed at elucidating how OEO promotes the intestinal barrier integrity in a pig model. Pigs were fed a control diet alone or one supplemented with 25 mg/kg of OEO for 4 weeks. The OEO-treated pigs showed decreased (P<0.05 endotoxin level in serum and increased (P<0.05 villus height and expression of occludin and zonula occludens-1 (ZO-1 in the jejunum. These results demonstrated that the integrity of intestinal barrier was improved by OEO treatment. The OEO-treated pigs had a lower (P<0.05 population of Escherichia coli in the jejunum, ileum, and colon than the control. This is in accordance with the greater inactivation (P<0.05 of inflammation, which was reflected by the mitogen-activated protein kinase (MAPK, protein kinase B (Akt, and nuclear factor κB (NF-κB signaling pathways and expression of inflammatory cytokines in the jejunum. Our results show that OEO promotes intestinal barrier integrity, probably through modulating intestinal bacteria and immune status in pigs.

  3. Anti-inflammatory Effects of Fungal Metabolites in Mouse Intestine as Revealed by In vitro Models

    Directory of Open Access Journals (Sweden)

    Dominik Schreiber

    2017-08-01

    Full Text Available Inflammatory bowel diseases (IBD, which include Crohn's disease and ulcerative colitis, are chronic inflammatory disorders that can affect the whole gastrointestinal tract or the colonic mucosal layer. Current therapies aiming to suppress the exaggerated immune response in IBD largely rely on compounds with non-satisfying effects or side-effects. Therefore, new therapeutical options are needed. In the present study, we investigated the anti-inflammatory effects of the fungal metabolites, galiellalactone, and dehydrocurvularin in both an in vitro intestinal inflammation model, as well as in isolated myenteric plexus and enterocyte cells. Administration of a pro-inflammatory cytokine mix through the mesenteric artery of intestinal segments caused an up-regulation of inflammatory marker genes. Treatment of the murine intestinal segments with galiellalactone or dehydrocurvularin by application through the mesenteric artery significantly prevented the expression of pro-inflammatory marker genes on the mRNA and the protein level. Comparable to the results in the perfused intestine model, treatment of primary enteric nervous system (ENS cells from the murine intestine with the fungal compounds reduced expression of cytokines such as IL-6, TNF-α, IL-1β, and inflammatory enzymes such as COX-2 and iNOS on mRNA and protein levels. Similar anti-inflammatory effects of the fungal metabolites were observed in the human colorectal adenocarcinoma cell line DLD-1 after stimulation with IFN-γ (10 ng/ml, TNF-α (10 ng/ml, and IL-1β (5 ng/ml. Our results show that the mesenterially perfused intestine model provides a reliable tool for the screening of new therapeutics with limited amounts of test compounds. Furthermore, we could characterize the anti-inflammatory effects of two novel active compounds, galiellalactone, and dehydrocurvularin which are interesting candidates for studies with chronic animal models of IBD.

  4. Free Total Rhubarb Anthraquinones Protect Intestinal Injury via Regulation of the Intestinal Immune Response in a Rat Model of Severe Acute Pancreatitis

    Directory of Open Access Journals (Sweden)

    Yuxia Xiong

    2018-02-01

    Full Text Available Intestinal mucosal immune barrier dysfunction plays a key role in the pathogenesis of severe acute pancreatitis (SAP. Rhubarb is a commonly used traditional Chinese medicine as a laxative in China. It markedly protects pancreatic acinar cells from trypsin-induced injury in rats. Free total rhubarb anthraquinones (FTRAs isolated and extracted from rhubarb display the beneficial effects of antibacteria, anti-inflammation, antivirus, and anticancer. The principal aim of the present study was to investigate the effects of FTRAs on the protection of intestinal injury and modification of the intestinal barrier function through regulation of intestinal immune function in rats with SAP. We established a rat model of SAP by injecting 3.5% sodium taurocholate (STC, 350 mg/kg into the biliopancreatic duct via retrograde injection and treated the rats with FTRAs (36 or 72 mg/kg or normal saline (control immediately and 12 h after STC injection. Then, we evaluated the protective effect of FTRAs on intestinal injury by pathological analysis and determined the levels of endotoxin (ET, interleukin 1β (IL-1β, tumor necrosis factor α (TNF-α, nitric oxide (NO, myeloperoxidase (MPO, capillary permeability, nucleotide-binding oligomerization domain-like receptors 3 (NLRP3, apoptosis-associated speck-like protein containing a CARD domain (ASC, casepase-1, secretary immunoglobulin A (SIgA, regulatory T cells (Tregs, and the ratio of Th1/Th2 in the blood and/or small intestinal tissues or mesenteric lymph node (MLN cells. Moreover, the chemical profile of FTRAs was analyzed by HPLC-UV chromatogram. The results showed that FTRAs significantly protected intestinal damage and decreased the levels of ET, IL-1β, TNF-α, and NO in the blood and TNF-α, IL-1β, and protein extravasation in the intestinal tissues in SAP rats. Furthermore, FTRAs significantly decreased the expressions of NLRP3, ASC, and caspase-1, the number of Tregs and the ratio of Th1/Th2, while

  5. Transcriptional modulation of intestinal innate defense/inflammation genes by preterm infant microbiota in a humanized gnotobiotic mouse model.

    Science.gov (United States)

    Lu, Lei; Yu, Yueyue; Guo, Yuee; Wang, Yunwei; Chang, Eugene B; Claud, Erika C

    2015-01-01

    It is known that postnatal functional maturation of the small intestine is facilitated by microbial colonization of the gut. Preterm infants exhibit defects in gut maturation, weak innate immunity against intestinal infection and increased susceptibility to inflammatory disorders, all of which may be related to the inappropriate microbial colonization of their immature intestines. The earliest microbes to colonize the preterm infant gut encounter a naïve, immature intestine. Thus this earliest microbiota potentially has the greatest opportunity to fundamentally influence intestinal development and immune function. The aim of this study was to characterize the effect of early microbial colonization on global gene expression in the distal small intestine during postnatal gut development. Gnotobiotic mouse models with experimental colonization by early (prior to two weeks of life) intestinal microbiota from preterm human infants were utilized. Microarray analysis was used to assess global gene expression in the intestinal epithelium. Multiple intestinal genes involved in metabolism, cell cycle regulation, cell-cell or cell-extracellular matrix communication, and immune function are developmental- and intestinal microbiota- regulated. Using a humanized gnotobiotic mouse model, we demonstrate that certain early preterm infant microbiota from prior to 2 weeks of life specifically induce increased NF-κB activation and a phenotype of increased inflammation whereas other preterm microbiota specifically induce decreased NF-κB activation. These fundamental differences correlate with altered clinical outcomes and suggest the existence of optimal early microbial communities to improve health outcomes.

  6. A closed-loop model of the respiratory system: focus on hypercapnia and active expiration.

    Science.gov (United States)

    Molkov, Yaroslav I; Shevtsova, Natalia A; Park, Choongseok; Ben-Tal, Alona; Smith, Jeffrey C; Rubin, Jonathan E; Rybak, Ilya A

    2014-01-01

    Breathing is a vital process providing the exchange of gases between the lungs and atmosphere. During quiet breathing, pumping air from the lungs is mostly performed by contraction of the diaphragm during inspiration, and muscle contraction during expiration does not play a significant role in ventilation. In contrast, during intense exercise or severe hypercapnia forced or active expiration occurs in which the abdominal "expiratory" muscles become actively involved in breathing. The mechanisms of this transition remain unknown. To study these mechanisms, we developed a computational model of the closed-loop respiratory system that describes the brainstem respiratory network controlling the pulmonary subsystem representing lung biomechanics and gas (O2 and CO2) exchange and transport. The lung subsystem provides two types of feedback to the neural subsystem: a mechanical one from pulmonary stretch receptors and a chemical one from central chemoreceptors. The neural component of the model simulates the respiratory network that includes several interacting respiratory neuron types within the Bötzinger and pre-Bötzinger complexes, as well as the retrotrapezoid nucleus/parafacial respiratory group (RTN/pFRG) representing the central chemoreception module targeted by chemical feedback. The RTN/pFRG compartment contains an independent neural generator that is activated at an increased CO2 level and controls the abdominal motor output. The lung volume is controlled by two pumps, a major one driven by the diaphragm and an additional one activated by abdominal muscles and involved in active expiration. The model represents the first attempt to model the transition from quiet breathing to breathing with active expiration. The model suggests that the closed-loop respiratory control system switches to active expiration via a quantal acceleration of expiratory activity, when increases in breathing rate and phrenic amplitude no longer provide sufficient ventilation. The model

  7. A closed-loop model of the respiratory system: focus on hypercapnia and active expiration.

    Directory of Open Access Journals (Sweden)

    Yaroslav I Molkov

    Full Text Available Breathing is a vital process providing the exchange of gases between the lungs and atmosphere. During quiet breathing, pumping air from the lungs is mostly performed by contraction of the diaphragm during inspiration, and muscle contraction during expiration does not play a significant role in ventilation. In contrast, during intense exercise or severe hypercapnia forced or active expiration occurs in which the abdominal "expiratory" muscles become actively involved in breathing. The mechanisms of this transition remain unknown. To study these mechanisms, we developed a computational model of the closed-loop respiratory system that describes the brainstem respiratory network controlling the pulmonary subsystem representing lung biomechanics and gas (O2 and CO2 exchange and transport. The lung subsystem provides two types of feedback to the neural subsystem: a mechanical one from pulmonary stretch receptors and a chemical one from central chemoreceptors. The neural component of the model simulates the respiratory network that includes several interacting respiratory neuron types within the Bötzinger and pre-Bötzinger complexes, as well as the retrotrapezoid nucleus/parafacial respiratory group (RTN/pFRG representing the central chemoreception module targeted by chemical feedback. The RTN/pFRG compartment contains an independent neural generator that is activated at an increased CO2 level and controls the abdominal motor output. The lung volume is controlled by two pumps, a major one driven by the diaphragm and an additional one activated by abdominal muscles and involved in active expiration. The model represents the first attempt to model the transition from quiet breathing to breathing with active expiration. The model suggests that the closed-loop respiratory control system switches to active expiration via a quantal acceleration of expiratory activity, when increases in breathing rate and phrenic amplitude no longer provide sufficient

  8. Loop calculations for the non-commutative U*(1) gauge field model with oscillator term

    International Nuclear Information System (INIS)

    Blaschke, Daniel N.; Grosse, Harald; Kronberger, Erwin; Schweda, Manfred; Wohlgenannt, Michael

    2010-01-01

    Motivated by the success of the non-commutative scalar Grosse-Wulkenhaar model, a non-commutative U * (1) gauge field theory including an oscillator-like term in the action has been put forward in (Blaschke et al. in Europhys. Lett. 79:61002, 2007). The aim of the current work is to analyze whether that action can lead to a fully renormalizable gauge model on non-commutative Euclidean space. In a first step, explicit one-loop graph computations are hence presented, and their results as well as necessary modifications of the action are successively discussed. (orig.)

  9. Reduced Moment-Based Models for Oxygen Precipitates and Dislocation Loops in Silicon

    Science.gov (United States)

    Trzynadlowski, Bart

    The demand for ever smaller, higher-performance integrated circuits and more efficient, cost-effective solar cells continues to push the frontiers of process technology. Fabrication of silicon devices requires extremely precise control of impurities and crystallographic defects. Failure to do so not only reduces performance, efficiency, and yield, it threatens the very survival of commercial enterprises in today's fiercely competitive and price-sensitive global market. The presence of oxygen in silicon is an unavoidable consequence of the Czochralski process, which remains the most popular method for large-scale production of single-crystal silicon. Oxygen precipitates that form during thermal processing cause distortion of the surrounding silicon lattice and can lead to the formation of dislocation loops. Localized deformation caused by both of these defects introduces potential wells that trap diffusing impurities such as metal atoms, which is highly desirable if done far away from sensitive device regions. Unfortunately, dislocations also reduce the mechanical strength of silicon, which can cause wafer warpage and breakage. Engineers must negotiate this and other complex tradeoffs when designing fabrication processes. Accomplishing this in a complex, modern process involving a large number of thermal steps is impossible without the aid of computational models. In this dissertation, new models for oxygen precipitation and dislocation loop evolution are described. An oxygen model using kinetic rate equations to evolve the complete precipitate size distribution was developed first. This was then used to create a reduced model tracking only the moments of the size distribution. The moment-based model was found to run significantly faster than its full counterpart while accurately capturing the evolution of oxygen precipitates. The reduced model was fitted to experimental data and a sensitivity analysis was performed to assess the robustness of the results. Source

  10. The small intestine and irritable bowel syndrome (IBS): a batch process model.

    Science.gov (United States)

    Dobson, Brian C

    2008-11-01

    Faults in a batch process model of the small intestine create the symptoms of all types of irritable bowel syndrome. The model has three sequential processing sections corresponding to the natural divisions of the intestine. It is governed by a brain controller that is divided into four sub-controllers, each with a unique neurotransmitter. Each section has a sub-controller to manage transport. Sensors in the walls of the intestine provide input and output goes to the muscles lining the walls of the intestine. The output controls the speed of the food soup, moves it in both directions, mixes it, controls absorption, and transfers it to the next section at the correct speed (slow). The fourth sub-controller manages the addition of chemicals. It obtains input from the first section of the process via the signalling hormone Cholecystokinin and sends output to the muscles that empty the gall bladder and pancreas. The correct amounts of bile salts and enzymes are then added to the first section. The sub-controllers produce output only when input is received. When output is missing the enteric nervous system applies a default condition. This default condition normally happens when no food is in the intestine. If food is in the intestine and a transport sub-controller fails to provide output then the default condition moves the food soup to the end of that section. The movement is in one direction only (forward), at a speed dependent on the amount and type of fibre present. Cereal, bean and vegetable fibre causes high speeds. This default high speed transport causes irritable bowel syndrome. A barrier is created when a section moving fast at the default speed, precedes a section controlled by a transport sub-controller. Then the sub-controller constricts the intestine to stop the fast flow. The barrier causes constipation, cramping, and bloating. Diarrhoea results when the section terminating the process moves at the fast default speed. Two problems can occur to prevent

  11. Closed-loop stimulation of hypoglossal nerve in a dog model of upper airway obstruction.

    Science.gov (United States)

    Sahin, M; Durand, D M; Haxhiu, M A

    2000-07-01

    Electrical stimulation of upper airway (UAW) muscles has been under investigation as a treatment method for obstructive sleep apnea (OSA). Particular attention has been given to the electrical activation of the genioglossal muscle, either directly or via the stimulation of the hypoglossal nerve (HG), since the genioglossus is the main tongue protrusor muscle. Regardless of the stimulation site or method, an implantable electrical stimulation device for OSA patients will require a reliable method for detection of obstructive breaths to apply the stimulation when needed. In this paper, we test the hypothesis that the activity of the HG nerve can be used as a feedback signal for closed-loop stimulation of the HG nerve in an animal model of UAW obstruction where a force is applied on the submental region to physically narrow the airways. As an advantage, the method uses a single electrode for both recording and stimulation of the HG nerve. Simple linear filtering techniques were found to be adequate for producing the trigger signal for the electrical stimulation from the HG recordings. Esophageal pressure, which was used to estimate the size of the UAW passage, returned to the preloading values during closed-loop stimulation of the HG nerve. The data demonstrate the feasibility of the closed-loop stimulation of the HG nerve using its activity as the feedback signal.

  12. Determination of Autophagy in the Caco-2 Spontaneously Differentiating Model of Intestinal Epithelial Cells.

    Science.gov (United States)

    Tunçer, Sinem; Banerjee, Sreeparna

    2017-08-27

    The Caco-2 colorectal cancer cell line is widely used as a model for intestinal differentiation and barrier function. These cells, upon reaching confluency, spontaneously differentiate into enterocyte-like cells, synthesize intestinal enzymes, and form domes. Caco-2 cells also undergo autophagy in the course of differentiation. The criteria to establish the induction of autophagy in cells are already well established. Here, we describe the protocol for the spontaneous differentiation of Caco-2 cells and the detection of autophagy using Western blot, flow cytometry, and immunofluorescence.

  13. Development of microfluidic cell culture devices towards an in vitro human intestinal barrier model

    DEFF Research Database (Denmark)

    Tan, Hsih-Yin

    Existing in vitro models of the human intestine such as the established epithelial cell line, Caco-2, cultured on porous membranes have been extensively used for assessing and predicting permeability and absorption of oral drugs in the pharmaceutical industries. However, such in vitro human intes...

  14. Prefabrication of axial vascularized tissue engineering coral bone by an arteriovenous loop: A better model

    Energy Technology Data Exchange (ETDEWEB)

    Dong Qingshan [Department of Oral and Maxillofacial Surgery, Wuhan General Hospital of Guangzhou Military Command, Wuhan 430070 (China); Shang Hongtao; Wu Wei [Department of Oral and Maxillofacial Surgery, School of Stomatology, Fourth Military Medical University, Xi' an 710032 (China); Chen Fulin [Lab of Tissue Engineering, Faculty of Life Science, Northwest University, Xi' an 710069 (China); Zhang Junrui [Department of Oral and Maxillofacial Surgery, School of Stomatology, Fourth Military Medical University, Xi' an 710032 (China); Guo Jiaping [Department of Oral and Maxillofacial Surgery, Wuhan General Hospital of Guangzhou Military Command, Wuhan 430070 (China); Mao Tianqiu, E-mail: tianqiumao@126.com [Department of Oral and Maxillofacial Surgery, School of Stomatology, Fourth Military Medical University, Xi' an 710032 (China)

    2012-08-01

    The most important problem for the survival of thick 3-dimensional tissues is the lack of vascularization in the context of bone tissue engineering. In this study, a modified arteriovenous loop (AVL) was developed to prefabricate an axial vascularized tissue engineering coral bone in rabbit, with comparison of the arteriovenous bundle (AVB) model. An arteriovenous fistula between rabbit femoral artery and vein was anastomosed to form an AVL. It was placed in a circular side groove of the coral block. The complex was wrapped with an expanded-polytetrafluoroethylene membrane and implanted beneath inguinal skin. After 2, 4, 6 and 8 weeks, the degree of vascularization was evaluated by India ink perfusion, histological examination, vascular casts, and scanning electron microscopy images of vascular endangium. Newly formed fibrous tissues and vasculature extended over the surfaces and invaded the interspaces of entire coral block. The new blood vessels robustly sprouted from the AVL. Those invaginated cavities in the vascular endangium from scanning electron microscopy indicated vessel's sprouted pores. Above indexes in AVL model are all superior to that in AVB model, indicating that the modified AVL model could more effectively develop vascularization in larger tissue engineering bone. - Highlights: Black-Right-Pointing-Pointer A modified arteriovenous loop (AVL) model in rabbit was developed in this study. Black-Right-Pointing-Pointer Axial prevascularization was induced in a larger coral block by using the AVL. Black-Right-Pointing-Pointer The prefabrication of axial vascularized coral bone is superior as vascular carrier.

  15. Prefabrication of axial vascularized tissue engineering coral bone by an arteriovenous loop: A better model

    International Nuclear Information System (INIS)

    Dong Qingshan; Shang Hongtao; Wu Wei; Chen Fulin; Zhang Junrui; Guo Jiaping; Mao Tianqiu

    2012-01-01

    The most important problem for the survival of thick 3-dimensional tissues is the lack of vascularization in the context of bone tissue engineering. In this study, a modified arteriovenous loop (AVL) was developed to prefabricate an axial vascularized tissue engineering coral bone in rabbit, with comparison of the arteriovenous bundle (AVB) model. An arteriovenous fistula between rabbit femoral artery and vein was anastomosed to form an AVL. It was placed in a circular side groove of the coral block. The complex was wrapped with an expanded-polytetrafluoroethylene membrane and implanted beneath inguinal skin. After 2, 4, 6 and 8 weeks, the degree of vascularization was evaluated by India ink perfusion, histological examination, vascular casts, and scanning electron microscopy images of vascular endangium. Newly formed fibrous tissues and vasculature extended over the surfaces and invaded the interspaces of entire coral block. The new blood vessels robustly sprouted from the AVL. Those invaginated cavities in the vascular endangium from scanning electron microscopy indicated vessel's sprouted pores. Above indexes in AVL model are all superior to that in AVB model, indicating that the modified AVL model could more effectively develop vascularization in larger tissue engineering bone. - Highlights: ► A modified arteriovenous loop (AVL) model in rabbit was developed in this study. ► Axial prevascularization was induced in a larger coral block by using the AVL. ► The prefabrication of axial vascularized coral bone is superior as vascular carrier.

  16. Heat transport modeling for the design of a low enthalpy open-loop system

    Directory of Open Access Journals (Sweden)

    Leonardo Piccinini

    2012-12-01

    Full Text Available A case study of hydrogeological characterization and heat transport modeling for the design of a low enthalpy system in the Province of Treviso (Italy is here presented. It is an open loop system that pumps and re-injects groundwater from a confined aquifer of the high Veneto plain. This type of systems is the most efficient in terms of yield, but its construction is highly conditioned by the availability of groundwater resource and by the environmental laws related to groundwater exploitation. Groundwater flow modeling with MODFLOW 2005 led to a good aquifer parameters estimation, by means of the quantitative calibration of a pumping test made on the pumping well and an observation piezometer. Then, with the heat transport modeling with SEAWAT 4 the distance between pumping well and re-injecting well has been optimized, avoiding so the thermal feedback effect. The lack of sitespecific data for dispersivity parameters has been solved through a sensitivity analysis on the main dispersivity parameters of heat transport. Finally, in order to comply with the environmental laws, a long-term forecasting simulation (duration of 20 years has been set up in order to evaluate the open loop system thermal impact on the aquifer. The obtained results put in evidence that the design of low enthalpy systems strongly needs a detailed hydrogeological characterization of the aquifer interested by the pumping and that numerical modeling is the most effective tool in support of the definition of the optimal distance between pumping and re-injecting wells in the open loop systems.

  17. Consensus hologram QSAR modeling for the prediction of human intestinal absorption.

    Science.gov (United States)

    Moda, Tiago L; Andricopulo, Adriano D

    2012-04-15

    Consistent in silico models for ADME properties are useful tools in early drug discovery. Here, we report the hologram QSAR modeling of human intestinal absorption using a dataset of 638 compounds with experimental data associated. The final validated models are consistent and robust for the consensus prediction of this important pharmacokinetic property and are suitable for virtual screening applications. Copyright © 2012 Elsevier Ltd. All rights reserved.

  18. Second and third stages of project for the implementation of two asymmetric cooling loops modeled by the ALMOD3 code

    International Nuclear Information System (INIS)

    Dominguez, L.; Camargo, C.T.M.

    1985-04-01

    The second and third steps of the project for implementation of two non-symmetric cooling loops modeled by the ALMOD3 computer code are presented. These steps consists in activate the option for 2 loops already present in ALMOD3 original version and to introduce the GEVAP model for one of the two steam generators. In ALMOD3 original version the simulation of two non-symmetric loops was only possible using external functions, which provide the removed heat for each time step for one of the steam generators. With the introduction of GEVAP model, it is possible to obtain more accurate results. Due to its simplicity, the computer time required for execution is short. The results obtained in Angra 1 simulations are presented, analysed and compared with results obtained using one loop for simulating symmetric transients. (Author) [pt

  19. Effects of hemin and nitrite on intestinal tumorigenesis in the A/J Min/+ mouse model.

    Directory of Open Access Journals (Sweden)

    Marianne Sødring

    Full Text Available Red and processed meats are considered risk factors for colorectal cancer (CRC; however, the underlying mechanisms are still unclear. One cause for the potential link between CRC and meat is the heme iron in red meat. Two pathways by which heme and CRC promotion may be linked have been suggested: fat peroxidation and N-nitrosation. In the present work we have used the novel A/J Min/+ mouse model to test the effects of dietary hemin (a model of red meat, and hemin in combination with nitrite (a model of processed meat on intestinal tumorigenesis. Mice were fed a low Ca2+ and vitamin D semi-synthetic diet with added hemin and/or nitrite for 8 weeks post weaning, before termination followed by excision and examination of the intestinal tract. Our results indicate that dietary hemin decreased the number of colonic lesions in the A/J Min/+ mouse. However, our results also showed that the opposite occurred in the small intestine, where dietary hemin appeared to stimulate tumor growth. Furthermore, we find that nitrite, which did not have an effect in the colon, appeared to have a suppressive effect on tumor growth in the small intestine.

  20. Intestine-Specific Mttp Deletion Decreases Mortality and Prevents Sepsis-Induced Intestinal Injury in a Murine Model of Pseudomonas aeruginosa Pneumonia

    Science.gov (United States)

    Dominguez, Jessica A.; Xie, Yan; Dunne, W. Michael; Yoseph, Benyam P.; Burd, Eileen M.; Coopersmith, Craig M.; Davidson, Nicholas O.

    2012-01-01

    Background The small intestine plays a crucial role in the pathophysiology of sepsis and has been referred to as the “motor” of the systemic inflammatory response. One proposed mechanism is that toxic gut-derived lipid factors, transported in mesenteric lymph, induce systemic injury and distant organ failure. However, the pathways involved are yet to be defined and the role of intestinal chylomicron assembly and secretion in transporting these lipid factors is unknown. Here we studied the outcome of sepsis in mice with conditional, intestine-specific deletion of microsomal triglyceride transfer protein (Mttp-IKO), which exhibit a block in chylomicron assembly together with lipid malabsorption. Methodology/Principal Findings Mttp-IKO mice and controls underwent intratracheal injection with either Pseudomonas aeruginosa or sterile saline. Mttp-IKO mice exhibited decreased seven-day mortality, with 0/20 (0%) dying compared to 5/17 (29%) control mice (p<0.05). This survival advantage in Mttp-IKO mice, however, was not associated with improvements in pulmonary bacterial clearance or neutrophil infiltration. Rather, Mttp-IKO mice exhibited protection against sepsis-associated decreases in villus length and intestinal proliferation and were also protected against increased intestinal apoptosis, both central features in control septic mice. Serum IL-6 levels, a major predictor of mortality in human and mouse models of sepsis, were elevated 8-fold in septic control mice but remained unaltered in septic Mttp-IKO mice. Serum high density lipoprotein (HDL) levels were reduced in septic control mice but were increased in septic Mttp-IKO mice. The decreased levels of HDL were associated with decreased hepatic expression of apolipoprotein A1 in septic control mice. Conclusions/Significance These studies suggest that strategies directed at blocking intestinal chylomicron secretion may attenuate the progression and improve the outcome of sepsis through effects mediated by

  1. Intestine-specific Mttp deletion decreases mortality and prevents sepsis-induced intestinal injury in a murine model of Pseudomonas aeruginosa pneumonia.

    Directory of Open Access Journals (Sweden)

    Jessica A Dominguez

    Full Text Available The small intestine plays a crucial role in the pathophysiology of sepsis and has been referred to as the "motor" of the systemic inflammatory response. One proposed mechanism is that toxic gut-derived lipid factors, transported in mesenteric lymph, induce systemic injury and distant organ failure. However, the pathways involved are yet to be defined and the role of intestinal chylomicron assembly and secretion in transporting these lipid factors is unknown. Here we studied the outcome of sepsis in mice with conditional, intestine-specific deletion of microsomal triglyceride transfer protein (Mttp-IKO, which exhibit a block in chylomicron assembly together with lipid malabsorption.Mttp-IKO mice and controls underwent intratracheal injection with either Pseudomonas aeruginosa or sterile saline. Mttp-IKO mice exhibited decreased seven-day mortality, with 0/20 (0% dying compared to 5/17 (29% control mice (p<0.05. This survival advantage in Mttp-IKO mice, however, was not associated with improvements in pulmonary bacterial clearance or neutrophil infiltration. Rather, Mttp-IKO mice exhibited protection against sepsis-associated decreases in villus length and intestinal proliferation and were also protected against increased intestinal apoptosis, both central features in control septic mice. Serum IL-6 levels, a major predictor of mortality in human and mouse models of sepsis, were elevated 8-fold in septic control mice but remained unaltered in septic Mttp-IKO mice. Serum high density lipoprotein (HDL levels were reduced in septic control mice but were increased in septic Mttp-IKO mice. The decreased levels of HDL were associated with decreased hepatic expression of apolipoprotein A1 in septic control mice.These studies suggest that strategies directed at blocking intestinal chylomicron secretion may attenuate the progression and improve the outcome of sepsis through effects mediated by metabolic and physiological adaptations in both intestinal and

  2. Modeling and analysis of circulation variables of continuous sorbent loop cycling for CO{sub 2} capture

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Kee-Youn [Seoul National University of Science and Technology, Seoul (Korea, Republic of); Park, Jun-Soo; Park, Myung-June [Ajou University, Suwon (Korea, Republic of)

    2016-04-15

    Carbon capture and storage (CCS) technologies are a cornerstone for reducing CO{sub 2} emissions from energy and energy-intensive industries. Among the various CCS technologies, solid sorbent looping systems are considered to be potentially promising solutions for reducing CO{sub 2} capture energy penalty. We present an evaluation module for a carbonator with sorbent looping cycle to calculate the carbonation efficiency. The module incorporates a simple sorbent activity model, and the solid/gas balances are constructed by assuming simple reactor mixing quality. By conducting simulations, we examine the variation in the carbonation efficiencies as a function of the sorbent looping operation factors and discuss an optimum operating strategy.

  3. Three-loop Standard Model effective potential at leading order in strong and top Yukawa couplings

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Stephen P. [Santa Barbara, KITP

    2014-01-08

    I find the three-loop contribution to the effective potential for the Standard Model Higgs field, in the approximation that the strong and top Yukawa couplings are large compared to all other couplings, using dimensional regularization with modified minimal subtraction. Checks follow from gauge invariance and renormalization group invariance. I also briefly comment on the special problems posed by Goldstone boson contributions to the effective potential, and on the numerical impact of the result on the relations between the Higgs vacuum expectation value, mass, and self-interaction coupling.

  4. Little strings, quasi-topological sigma model on loop group, and toroidal Lie algebras

    Science.gov (United States)

    Ashwinkumar, Meer; Cao, Jingnan; Luo, Yuan; Tan, Meng-Chwan; Zhao, Qin

    2018-03-01

    We study the ground states and left-excited states of the Ak-1 N = (2 , 0) little string theory. Via a theorem by Atiyah [1], these sectors can be captured by a supersymmetric nonlinear sigma model on CP1 with target space the based loop group of SU (k). The ground states, described by L2-cohomology classes, form modules over an affine Lie algebra, while the left-excited states, described by chiral differential operators, form modules over a toroidal Lie algebra. We also apply our results to analyze the 1/2 and 1/4 BPS sectors of the M5-brane worldvolume theory.

  5. Little strings, quasi-topological sigma model on loop group, and toroidal Lie algebras

    Directory of Open Access Journals (Sweden)

    Meer Ashwinkumar

    2018-03-01

    Full Text Available We study the ground states and left-excited states of the Ak−1 N=(2,0 little string theory. Via a theorem by Atiyah [1], these sectors can be captured by a supersymmetric nonlinear sigma model on CP1 with target space the based loop group of SU(k. The ground states, described by L2-cohomology classes, form modules over an affine Lie algebra, while the left-excited states, described by chiral differential operators, form modules over a toroidal Lie algebra. We also apply our results to analyze the 1/2 and 1/4 BPS sectors of the M5-brane worldvolume theory.

  6. GoSam 2.0. Automated one loop calculations within and beyond the standard model

    International Nuclear Information System (INIS)

    Greiner, Nicolas; Deutsches Elektronen-Synchrotron

    2014-10-01

    We present GoSam 2.0, a fully automated framework for the generation and evaluation of one loop amplitudes in multi leg processes. The new version offers numerous improvements both on generational aspects as well as on the reduction side. This leads to a faster and more stable code for calculations within and beyond the Standard Model. Furthermore it contains the extended version of the standardized interface to Monte Carlo programs which allows for an easy combination with other existing tools. We briefly describe the conceptual innovations and present some phenomenological results.

  7. Mobile application MDDCS for modeling the expansion dynamics of a dislocation loop in FCC metals

    Science.gov (United States)

    Kirilyuk, Vasiliy; Petelin, Alexander; Eliseev, Andrey

    2017-11-01

    A mobile version of the software package Dynamic Dislocation of Crystallographic Slip (MDDCS) designed for modeling the expansion dynamics of dislocation loops and formation of a crystallographic slip zone in FCC-metals is examined. The paper describes the possibilities for using MDDCS, the application interface, and the database scheme. The software has a simple and intuitive interface and does not require special training. The user can set the initial parameters of the experiment, carry out computational experiments, export parameters and results of the experiment into separate text files, and display the experiment results on the device screen.

  8. Feedback loops and temporal misalignment in component-based hydrologic modeling

    Science.gov (United States)

    Elag, Mostafa M.; Goodall, Jonathan L.; Castronova, Anthony M.

    2011-12-01

    In component-based modeling, a complex system is represented as a series of loosely integrated components with defined interfaces and data exchanges that allow the components to be coupled together through shared boundary conditions. Although the component-based paradigm is commonly used in software engineering, it has only recently been applied for modeling hydrologic and earth systems. As a result, research is needed to test and verify the applicability of the approach for modeling hydrologic systems. The objective of this work was therefore to investigate two aspects of using component-based software architecture for hydrologic modeling: (1) simulation of feedback loops between components that share a boundary condition and (2) data transfers between temporally misaligned model components. We investigated these topics using a simple case study where diffusion of mass is modeled across a water-sediment interface. We simulated the multimedia system using two model components, one for the water and one for the sediment, coupled using the Open Modeling Interface (OpenMI) standard. The results were compared with a more conventional numerical approach for solving the system where the domain is represented by a single multidimensional array. Results showed that the component-based approach was able to produce the same results obtained with the more conventional numerical approach. When the two components were temporally misaligned, we explored the use of different interpolation schemes to minimize mass balance error within the coupled system. The outcome of this work provides evidence that component-based modeling can be used to simulate complicated feedback loops between systems and guidance as to how different interpolation schemes minimize mass balance error introduced when components are temporally misaligned.

  9. Profit Analysis and Supply Chain Planning Model for Closed-Loop Supply Chain in Fashion Industry

    Directory of Open Access Journals (Sweden)

    Jisoo Oh

    2014-12-01

    Full Text Available In recent decades, due to market growth and use of synthetic fiber, the fashion industry faces a rapid increase of CO2 emission throughout the production cycle and raises environmental issues in recovery processing. This study proposes a closed-loop supply chain (CLSC structure in fashion industry and develops its planning model as multi-objective mixed integer linear programming to find an optimal trade-off between CLSC profit and CO2 emission. The planning model is associated with the profit analysis of each member in CLSC to find the optimal price of products on CLSC network. The model determines optimal production, transportation, and inventory quantities on CLSC network. The proposed models are validated using numerical experiments and sensitivity analyses, and from the results some managerial insights are addressed.

  10. Loop-induced decays of Higgs boson in the left-right twin Higgs model

    International Nuclear Information System (INIS)

    Yao-Bei, Liu; Xue-Lei, Wang; Yao-Bein, Liu; Xue-Lei, Wang

    2009-01-01

    We analyze the loop-induced decays of the Higgs boson into pairs of gluons and photons in the left-right twin Higgs model. The study shows that the deviation of the partial widths for these decays relative to their Standard Model (SM) values scales with 1/f 2 , where f ∼ TeV is the symmetry breaking scale in the model. For the mass mixing parameter M equals 150 GeV, the LHC and a linear e + e - collider would be sensitive to the deviation in Γ(H → gg) for f ≤ 770(660) GeV at the 1(2) σ level. So the Higgs boson processes at the LHC can be a sensitive probe for the left-right twin Higgs model. (authors)

  11. Two aspects of one loop structure: Unitarity delay in the Standard Model and modular invariance in string theory

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, C.

    1989-08-01

    We study two aspects of one loop structures in quantum field theories which describe two different areas of particle physics: the one loop unitarity behavior of the Standard Model of electroweak interactions and modular invariance of string model theory. Loop expansion has its importance in that it contains quantum fluctuations due to all physical states in the theory. Therefore, by studying the various models to one loop, we can understand how the contents of the theory can contribute to physically measurable quantities and how the consistency at quantum level restricts the physical states of the theory, as well. In the first half of the thesis, we study one loop corrections to the process {ital e}{sup +}{ital e}{sup {minus}} {yields} {ital W}{sup +}{ital W}{sup {minus}}. In this process, there is a delicate unitarity-saving cancellation between s-channel and t-channel tree level Feynman diagrams. If the one loop contribution due to heavy particles corrects the channels asymmetrically, the cancellation, hence unitarity, will be delayed up to the mass scale of these heavy particles. We refer to this phenomena as the unitarity delay effect. Due to this effect, cross section below these mass scales can have significant radiative corrections which may provide an appropriate window through which we can see the high energy structure of the Standard Model from relatively low energy experiments. In the second half, we will show how quantum consistency can restrict the physical states in string theory. 53 refs., 13 figs.

  12. Two aspects of one loop structure: Unitarity delay in the Standard Model and modular invariance in string theory

    International Nuclear Information System (INIS)

    Ahn, C.

    1989-08-01

    We study two aspects of one loop structures in quantum field theories which describe two different areas of particle physics: the one loop unitarity behavior of the Standard Model of electroweak interactions and modular invariance of string model theory. Loop expansion has its importance in that it contains quantum fluctuations due to all physical states in the theory. Therefore, by studying the various models to one loop, we can understand how the contents of the theory can contribute to physically measurable quantities and how the consistency at quantum level restricts the physical states of the theory, as well. In the first half of the thesis, we study one loop corrections to the process e + e - → W + W - . In this process, there is a delicate unitarity-saving cancellation between s-channel and t-channel tree level Feynman diagrams. If the one loop contribution due to heavy particles corrects the channels asymmetrically, the cancellation, hence unitarity, will be delayed up to the mass scale of these heavy particles. We refer to this phenomena as the unitarity delay effect. Due to this effect, cross section below these mass scales can have significant radiative corrections which may provide an appropriate window through which we can see the high energy structure of the Standard Model from relatively low energy experiments. In the second half, we will show how quantum consistency can restrict the physical states in string theory. 53 refs., 13 figs

  13. Closing the Loop for Memory Prostheses: Detecting the Role of Hippocampal Neural Ensembles Using Nonlinear Models

    Science.gov (United States)

    Hampson, Robert E.; Song, Dong; Chan, Rosa H.M.; Sweatt, Andrew J.; Riley, Mitchell R.; Goonawardena, Anushka V.; Marmarelis, Vasilis Z.; Gerhardt, Greg A.; Berger, Theodore W.; Deadwyler, Sam A.

    2012-01-01

    A major factor involved in providing closed loop feedback for control of neural function is to understand how neural ensembles encode online information critical to the final behavioral endpoint. This issue was directly assessed in rats performing a short-term delay memory task in which successful encoding of task information is dependent upon specific spatiotemporal firing patterns recorded from ensembles of CA3 and CA1 hippocampal neurons. Such patterns, extracted by a specially designed nonlinear multi-input multi-output (MIMO) nonlinear mathematical model, were used to predict successful performance online via a closed loop paradigm which regulated trial difficulty (time of retention) as a function of the “strength” of stimulus encoding. The significance of the MIMO model as a neural prosthesis has been demonstrated by substituting trains of electrical stimulation pulses to mimic these same ensemble firing patterns. This feature was used repeatedly to vary “normal” encoding as a means of understanding how neural ensembles can be “tuned” to mimic the inherent process of selecting codes of different strength and functional specificity. The capacity to enhance and tune hippocampal encoding via MIMO model detection and insertion of critical ensemble firing patterns shown here provides the basis for possible extension to other disrupted brain circuitry. PMID:22498704

  14. Epicatechin Used in the Treatment of Intestinal Inflammatory Disease: An Analysis by Experimental Models

    Directory of Open Access Journals (Sweden)

    Paulo César de Paula Vasconcelos

    2012-01-01

    Full Text Available Background. This study was pathway of (−-epicatechin (EC in the prevention and treatment of intestine inflammation in acute and chronic rat models. Methods. Intestine inflammation was induced in rats using TNBS. The morphological, inflammatory, immunohistochemical, and immunoblotting characteristics of colon samples were examined. The effects of EC were evaluated in an acute model at doses of 5, 10, 25, and 50 mg/kg by gavage for 5 days. The chronic colitis model was induced 1st day, and treated for 21 days. For the colitis relapse model, the induction was repeated on 14th. Results. EC10 and EC50 effectively reduced the lesion size, as assessed macroscopically; and confirmed by microscopy for EC10. The glutathione levels were higher in EC10 group but decreased COX-2 expression and increased cell proliferation (PC were observed, indicating an anti-inflammatory activity and a proliferation-stimulating effect. In the chronic colitis model, EC10 showed lower macroscopic and microscopic lesion scores and increase in glutathione levels. As in the acute model, a decrease in COX-2 expression and an increase in PC in EC10, the chronic model this increase maybe by the pathway EGF expression. Conclusion. These results confirm the activity of EC as an antioxidant that reduces of the lesion and that has the potential to stimulate tissue healing, indicating useful for preventing and treating intestine inflammation.

  15. Chemical form of selenium affects its uptake, transport and glutathione peroxidase activity in the human intestinal Caco-2 cell model

    Science.gov (United States)

    Determining the effect of selenium (Se) chemical form on uptake and transport in human intestinal cells is critical to assess Se bioavailability. In the present study, we measured the uptake and transport of various Se compounds in the human intestinal Caco-2 cell model. We found that two sources...

  16. Chemical form of selenium affects its uptake and transport in the human intestinal cell model, Caco-2

    Science.gov (United States)

    Determining the effect of selenium (Se) chemical form on uptake and transport in human intestinal cells is critical to assess Se bioavailability. In the present study, we measured the uptake and transport of various Se compounds in the human intestinal Caco-2 cell model. We found that two sources of...

  17. Optimization of micro-fabricated porous membranes for intestinal epithelial cell culture and in vitro modeling of the human intestinal barrier

    Science.gov (United States)

    Nair Gourikutty Sajay, Bhuvanendran; Yin, Chiam Su; Ramadan, Qasem

    2017-12-01

    In vitro modeling of organs could provide a controlled platform for studying physiological events and has great potential in the field of pharmaceutical development. Here, we describe the characterization of in vitro modeling of the human intestinal barrier mimicked using silicon porous membranes as a substrate. To mimic an intestinal in vivo setup as closely as possible, a porous substrate is required in a dynamic environment for the cells to grow rather than a static setup with an impermeable surface such as a petri dish. In this study, we focus on the detailed characterization of Caco-2 cells cultured on a silicon membrane with different pore sizes as well as the effect of dynamic fluid flow on the model. The porous silicon membrane together with continuous perfusion of liquid applying shear stress on the cells enhances the differentiation of polarized cells by providing access to the both their basal and apical surfaces. Membranes with pore sizes of 0.5-3 µm were used and a shear stress of ~0.03 dyne cm-2 was created by applying a low flow rate of 20 nl s-1. By providing these optimized conditions, cells were able to differentiate with columnar morphology, which developed microvilli structures on their apical side and tight junctions between adjacent cells like those in a healthy human intestinal barrier. In this setup, it is possible to study the important cellular functions of the intestine such as transport, absorption and secretion, and thus this model has great potential in drug screening.

  18. Intestinal epithelial apoptosis initiates gross bowel necrosis in an experimental rat model of neonatal necrotizing enterocolitis.

    Science.gov (United States)

    Jilling, Tamas; Lu, Jing; Jackson, Michele; Caplan, Michael S

    2004-04-01

    The histopathology of necrotizing enterocolitis (NEC) is characterized by destruction of the mucosal layer in initial stages and by transmural necrosis of the intestinal wall in advanced stages of the disease. To test the hypothesis that enhanced epithelial apoptosis is an initial event underlying the gross histologic changes, we analyzed epithelial apoptosis and tissue morphology in an animal model of NEC and evaluated the effect of caspase inhibition on the incidence of experimental NEC in this model. Apoptosis was analyzed with terminal deoxynucleotidyltransferase-mediated dUTP-FITC nick end labeling (TUNEL) staining in intestinal sections and by measuring caspase 3 activity from intestinal lysates of neonatal rats subjected to formula feeding and cold/asphyxia stress (FFCAS) and from mother-fed (MF) controls. Morphologic evaluation was based on hematoxylin and eosin staining of intestinal sections. FFCAS resulted in histologic changes consistent with NEC, which were absent from MF animals. FFCAS was also associated with a significantly increased rate of nuclear DNA fragmentation in the small intestinal epithelium compared with MF. Elevated tissue caspase 3 activity confirmed the presence of apoptosis in samples with increased DNA fragmentation. Analysis of the coincidence of morphologic damage and apoptosis in corresponding tissue sections indicated that apoptosis precedes gross morphologic changes in this model. Furthermore, supplementation of formula with 8 boc-aspartyl(OMe)-fluoromethylketone, a pan-caspase inhibitor, significantly reduced the incidences of apoptosis and experimental NEC. These findings indicate that in neonatal rats FFCAS induces epithelial apoptosis that serves as an underlying cause for subsequent gross tissue necrosis.

  19. Approximate Models for Closed-Loop Trajectory Tracking in Underactuated Systems

    Data.gov (United States)

    National Aeronautics and Space Administration — Control of robotic systems, as a field, spans both traditional closed-loop feedback techniques and modern machine learning strategies, which are primarily open-loop....

  20. Comparison of Mass Transfer Models for Determination of the Intestinal Permeability

    Directory of Open Access Journals (Sweden)

    P Zakeri-Milani

    2008-09-01

    Full Text Available Background and the purpose of the study: In determination of the permeability of the intestinal wall by external perfusion techniques, several models have been proposed. In the present study three models were used for experimental results that differ in their convection and diffusion assumptions. Material and Methods: Permeability coefficients for 13 compounds (metoprolol, propranolol, naproxen, ketoprofen, furosemide, hydrochlorothiazide, cimetidine, ranitidine, atenolol, piroxicam, antipyrine, ibuprofen and carbamazepine with known human intestinal permeability values were determined in anaesthetized rats by different mass transfer models and plotted versus the observed human intestinal permeabilities. Results: The calculated dimensionless wall permeability values were in the range of 0.37 - 4.85, 0.38-6.54 and 0.41-16.59 for complete radial mixing, mixing tank and laminar flow models respectively. The results indicated that all of the models work relatively well for our data despite fundamentally different assumptions. The wall permeabilities were in the order laminar flow > mixing tank > complete radial mixing. Conclusion: Although laminar flow model provides the most direct measure of the intrinsic wall permeability, it has limitations for highly permeable drugs such as ibuprofen. The normal physiological hydrodynamics is more complex and more investigation is required to find out the real hydrodynamics.

  1. One-loop potential in the new string model with negative stiffness

    International Nuclear Information System (INIS)

    Kleinert, H.; Chervyakov, A.M.; Nesterenko, V.V.

    1996-01-01

    The color-electric flux tube between quarks has a finite thickness therefore also a finite curvature stiffness. Contrary to earlier rigid-string proposal by Polyakov and Kleinert and motivated by the properties of a magnetic flux tube in a type-II superconductor, we put forward the hypothesis that the stiffness is negative. We set up and study the properties of an idealized string model with such negative stiffness. In contrast to the rigid string, the propagator in the new model has no unphysical pole. One-loop calculations show that the model generates an interquark potential which does not contain the square root singularity even for moderate values of a negative stiffness. At large distances, the potential has usual linearly rising term with the universal Luescher correction

  2. Fuzzy cognitive maps outmatch loop analysis in dynamic modeling of ecological systems

    Directory of Open Access Journals (Sweden)

    Alessandro Ferrarini

    2011-04-01

    Full Text Available Modeling natural systems is challenging due to their complexity in terms of variables, interactions, and dynamics. Much of this complexity is rooted in the existence of multiple ways through which acting variables affect each other. Besides the simple direct effects, numerous indirect effects emerge in ecological systems. Through an illustrative example, I exemplify here several advantages of fuzzy cognitive maps (FCM over loop analysis (LA in dynamic modeling of ecological systems. In addition to being able to incorporate information about the magnitude of variables interactions, FCM can make predictions about multiple simultaneous perturbations. Furthermore, FCM allow for the simulation of different magnitude of initial perturbations to the system. Last, FCM estimate the amount of variable increase/decrease, not just the likely direction of change. Hence, even if LA is still much more used than FCM in the scientific literature, FCM can be considered fitter than LA in modeling ecological systems.

  3. Modeling and Closed Loop Flight Testing of a Fixed Wing Micro Air Vehicle

    Directory of Open Access Journals (Sweden)

    Harikumar Kandath

    2018-03-01

    Full Text Available This paper presents the nonlinear six degrees of freedom dynamic modeling of a fixed wing micro air vehicle. The static derivatives of the micro air vehicle are obtained through the wind tunnel testing. The propeller effects on the lift, drag, pitching moment and side force are quantified through wind tunnel testing. The dynamic derivatives are obtained through empirical relations available in the literature. The trim conditions are computed for a straight and constant altitude flight condition. The linearized longitudinal and lateral state space models are obtained about trim conditions. The variations in short period mode, phugoid mode, Dutch roll mode, roll subsidence mode and spiral mode with respect to different trim operating conditions is presented. A stabilizing static output feedback controller is designed using the obtained model. Successful closed loop flight trials are conducted with the static output feedback controller.

  4. A RETRAN-02 model of the Sizewell B PCSR design - the Winfrith one-loop model, version 3.0

    International Nuclear Information System (INIS)

    Kinnersly, S.R.

    1983-11-01

    A one-loop RETRAN-02 model of the Sizewell B Pre Construction Safety Report (PCSR) design, set up at Winfrith, is described and documented. The model is suitable for symmetrical pressurised transients. Comparison with data from the Sizewell B PCSR shows that the model is a good representation of that design. Known errors, limitations and deficiencies are described. The mode of storage and maintenance at Winfrith using PROMUS (Program Maintenance and Update System) is noted. It is recommended that users modify the standard data by adding replacement cards to the end so as to aid in identification, use and maintenance of local versions. (author)

  5. Closed-Loop Supply Chain Models with Considering the Environmental Impact

    Science.gov (United States)

    Fallah, Mohammad

    2014-01-01

    Global warming and climate changes created by large scale emissions of greenhouse gases are a worldwide concern. Due to this, the issue of green supply chain management has received more attention in the last decade. In this study, a closed-loop logistic concept which serves the purposes of recycling, reuse, and recovery required in a green supply chain is applied to integrate the environmental issues into a traditional logistic system. Here, we formulate a comprehensive closed-loop model for the logistics planning considering profitability and ecological goals. In this way, we can achieve the ecological goal reducing the overall amount of CO2 emitted from journeys. Moreover, the profitability criterion can be supported in the cyclic network with the minimum costs and maximum service level. We apply three scenarios and develop problem formulations for each scenario corresponding to the specified regulations and investigate the effect of the regulation on the preferred transport mode and the emissions. To validate the models, some numerical experiments are worked out and a comparative analysis is investigated. PMID:25309960

  6. Closed-Loop Supply Chain Models with Considering the Environmental Impact

    Directory of Open Access Journals (Sweden)

    Amir Mohajeri

    2014-01-01

    Full Text Available Global warming and climate changes created by large scale emissions of greenhouse gases are a worldwide concern. Due to this, the issue of green supply chain management has received more attention in the last decade. In this study, a closed-loop logistic concept which serves the purposes of recycling, reuse, and recovery required in a green supply chain is applied to integrate the environmental issues into a traditional logistic system. Here, we formulate a comprehensive closed-loop model for the logistics planning considering profitability and ecological goals. In this way, we can achieve the ecological goal reducing the overall amount of CO2 emitted from journeys. Moreover, the profitability criterion can be supported in the cyclic network with the minimum costs and maximum service level. We apply three scenarios and develop problem formulations for each scenario corresponding to the specified regulations and investigate the effect of the regulation on the preferred transport mode and the emissions. To validate the models, some numerical experiments are worked out and a comparative analysis is investigated.

  7. Closed-loop supply chain models with considering the environmental impact.

    Science.gov (United States)

    Mohajeri, Amir; Fallah, Mohammad

    2014-01-01

    Global warming and climate changes created by large scale emissions of greenhouse gases are a worldwide concern. Due to this, the issue of green supply chain management has received more attention in the last decade. In this study, a closed-loop logistic concept which serves the purposes of recycling, reuse, and recovery required in a green supply chain is applied to integrate the environmental issues into a traditional logistic system. Here, we formulate a comprehensive closed-loop model for the logistics planning considering profitability and ecological goals. In this way, we can achieve the ecological goal reducing the overall amount of CO2 emitted from journeys. Moreover, the profitability criterion can be supported in the cyclic network with the minimum costs and maximum service level. We apply three scenarios and develop problem formulations for each scenario corresponding to the specified regulations and investigate the effect of the regulation on the preferred transport mode and the emissions. To validate the models, some numerical experiments are worked out and a comparative analysis is investigated.

  8. A model for improving microbial biofuel production using a synthetic feedback loop

    Energy Technology Data Exchange (ETDEWEB)

    Dunlop, Mary; Keasling, Jay; Mukhopadhyay, Aindrila

    2011-07-14

    Cells use feedback to implement a diverse range of regulatory functions. Building synthetic feedback control systems may yield insight into the roles that feedback can play in regulation since it can be introduced independently of native regulation, and alternative control architectures can be compared. We propose a model for microbial biofuel production where a synthetic control system is used to increase cell viability and biofuel yields. Although microbes can be engineered to produce biofuels, the fuels are often toxic to cell growth, creating a negative feedback loop that limits biofuel production. These toxic effects may be mitigated by expressing efflux pumps that export biofuel from the cell. We developed a model for cell growth and biofuel production and used it to compare several genetic control strategies for their ability to improve biofuel yields. We show that controlling efflux pump expression directly with a biofuel-responsive promoter is a straight forward way of improving biofuel production. In addition, a feed forward loop controller is shown to be versatile at dealing with uncertainty in biofuel production rates.

  9. Amelioration of Chemotherapy-Induced Intestinal Mucositis by Orally Administered Probiotics in a Mouse Model

    Science.gov (United States)

    Jiang, Chun-Bin; Cheng, Mei-Lien; Liu, Chia-Yuan; Chang, Szu-Wen; Chiang Chiau, Jen-Shiu; Lee, Hung-Chang

    2015-01-01

    Background and Aims Intestinal mucositis is a frequently encountered side effect in oncology patients undergoing chemotherapy. No well-established or up to date therapeutic strategies are available. To study a novel way to alleviate mucositis, we investigate the effects and safety of probiotic supplementation in ameliorating 5-FU-induced intestinal mucositis in a mouse model. Methods Seventy-two mice were injected saline or 5-Fluorouracil (5-FU) intraperitoneally daily. Mice were either orally administrated daily saline, probiotic suspension of Lactobacillus casei variety rhamnosus (Lcr35) or Lactobacillus acidophilus and Bifidobacterium bifidum (LaBi). Diarrhea score, pro-inflammatory cytokines serum levels, intestinal villus height and crypt depth and total RNA from tissue were assessed. Samples of blood, liver and spleen tissues were assessed for translocation. Results Marked diarrhea developed in the 5-FU groups but was attenuated after oral Lcr35 and LaBi administrations. Diarrhea scores decreased significantly from 2.64 to 1.45 and 0.80, respectively (Pprobiotics administration. We also found TNF-α, IL-1β and IL-6 mRNA expressions were up-regulated in intestinal mucositis tissues following 5-FU treatment (TNF-α: 4.35 vs. 1.18, IL-1β: 2.29 vs. 1.07, IL-6: 1.49 vs. 1.02) and that probiotics treatment suppressed this up-regulation (Pprobiotics Lcr35 and LaBi can ameliorate chemotherapy-induced intestinal mucositis in a mouse model. This suggests probiotics may serve as an alternative therapeutic strategy for the prevention or management of chemotherapy-induced mucositis in the future. PMID:26406888

  10. Curcumin Anti-Apoptotic Action in a Model of Intestinal Epithelial Inflammatory Damage.

    Science.gov (United States)

    Loganes, Claudia; Lega, Sara; Bramuzzo, Matteo; Vecchi Brumatti, Liza; Piscianz, Elisa; Valencic, Erica; Tommasini, Alberto; Marcuzzi, Annalisa

    2017-06-06

    The purpose of this study is to determine if a preventive treatment with curcumin can protect intestinal epithelial cells from inflammatory damage induced by IFNγ. To achieve this goal we have used a human intestinal epithelial cell line (HT29) treated with IFNγ to undergo apoptotic changes that can reproduce the damage of intestinal epithelia exposed to inflammatory cytokines. In this model, we measured the effect of curcumin (curcuminoid from Curcuma Longa ) added as a pre-treatment at different time intervals before stimulation with IFNγ. Curcumin administration to HT29 culture before the inflammatory stimulus IFNγ reduced the cell apoptosis rate. This effect gradually declined with the reduction of the curcumin pre-incubation time. This anti-apoptotic action by curcumin pre-treatment was paralleled by a reduction of secreted IL7 in the HT29 culture media, while there was no relevant change in the other cytokine levels. Even though curcumin pre-administration did not impact the activation of the NF-κB pathway, a slight effect on the phosphorylation of proteins in this inflammatory signaling pathway was observed. In conclusion, curcumin pre-treatment can protect intestinal cells from inflammatory damage. These results can be the basis for studying the preventive role of curcumin in inflammatory bowel diseases.

  11. Insights into the pathogenesis of enteropathogenic E. coli using an improved intestinal enterocyte model.

    Directory of Open Access Journals (Sweden)

    Paul Dean

    Full Text Available Enteropathogenic E. coli (EPEC is a human pathogen that targets the small intestine, causing severe and often fatal diarrhoea in infants. A defining feature of EPEC disease is the loss (effacement of absorptive microvilli (MV from the surface of small intestinal enterocytes. Much of our understanding of EPEC pathogenesis is derived from studies using cell lines such as Caco-2 - the most extensively used small intestinal model. However, previous work has revealed fundamental differences between Caco-2 cells and in vivo differentiated enterocytes in relation to MV effacement. This, and the high heterogeneity and low transfection efficiency of the Caco-2 cell line prompted the isolation of several sub-clones (NCL-1-12 to identify a more tractable and improved in vivo-like cell model. Along with established Caco-2 clones (TC-7, BBE1, sub-clones were assessed for growth rate, apical surface morphology, epithelial barrier function and transfection efficiency. TC-7 cells provided the best all-round clone and exhibited highest levels of ectopic gene expression following cell polarisation. Novel alterations in EGFP-labelled mitochondria, that were not previously documented in non-polarised cell types, highlighted the potential of the TC-7 model for defining dynamic enterocyte-specific changes during infection. Crucially, the TC-7 cell line also mimicked ex vivo derived enterocytes with regard to MV effacement, enabling a better dissection of the process. Effacement activity caused by the EPEC protein Map in the Caco-2 but not ex vivo model, was linked to a defect in suppressing its Cdc42-dependent functionality. MV effacement activity of the EPEC protein EspF in the TC-7 model was dependent on its N-WASP binding motif, which is also shown to play an essential role in epithelial barrier dysfunction. Together, this study highlights the many advantages of using TC-7 cells as a small intestinal model to study host-pathogen interactions.

  12. Loop Transfer Matrix and Loop Quantum Mechanics

    International Nuclear Information System (INIS)

    Savvidy, George K.

    2000-01-01

    The gonihedric model of random surfaces on a 3d Euclidean lattice has equivalent representation in terms of transfer matrix K(Q i ,Q f ), which describes the propagation of loops Q. We extend the previous construction of the loop transfer matrix to the case of nonzero self-intersection coupling constant κ. We introduce the loop generalization of Fourier transformation which allows to diagonalize transfer matrices, that depend on symmetric difference of loops only and express all eigenvalues of 3d loop transfer matrix through the correlation functions of the corresponding 2d statistical system. The loop Fourier transformation allows to carry out the analogy with quantum mechanics of point particles, to introduce conjugate loop momentum P and to define loop quantum mechanics. We also consider transfer matrix on 4d lattice which describes propagation of memebranes. This transfer matrix can also be diagonalized by using the generalized Fourier transformation, and all its eigenvalues are equal to the correlation functions of the corresponding 3d statistical system. In particular the free energy of the 4d membrane system is equal to the free energy of 3d gonihedric system of loops and is equal to the free energy of 2d Ising model. (author)

  13. Three-Dimensional Organotypic Co-Culture Model of Intestinal Epithelial Cells and Macrophages to Study "Salmonella Enterica" Colonization Patterns

    Science.gov (United States)

    Ott, Mark; Yang, J; Barilla, J.; Crabbe, A.; Sarker, S. F.; Liu, Y.

    2017-01-01

    Three-dimensional/3-D organotypic models of human intestinal epithelium mimic the differentiated form and function of parental tissues often not exhibited by 2-D monolayers and respond to Salmonella in ways that reflect in vivo infections. To further enhance the physiological relevance of 3-D models to more closely approximate in vivo intestinal microenvironments during infection, we developed and validated a novel 3-D intestinal co-culture model containing multiple epithelial cell types and phagocytic macrophages, and applied to study enteric infection by different Salmonella pathovars.

  14. Bending and Twisting the Embryonic Heart: A Computational Model for C-Looping Based on Realistic Geometry

    Directory of Open Access Journals (Sweden)

    Yunfei eShi

    2014-08-01

    Full Text Available The morphogenetic process of cardiac looping transforms the straight heart tube into a curved tube that resembles the shape of the future four-chambered heart. Although great progress has been made in identifying the molecular and genetic factors involved in looping, the physical mechanisms that drive this process have remained poorly understood. Recent work, however, has shed new light on this complicated problem. After briefly reviewing the current state of knowledge, we propose a relatively comprehensive hypothesis for the mechanics of the first phase of looping, termed c-looping, as the straight heart tube deforms into a c-shaped tube. According to this hypothesis, differential hypertrophic growth in the myocardium supplies the main forces that cause the heart tube to bend ventrally, while regional growth and contraction in the omphalomesenteric veins (primitive atria and compressive loads exerted by the splanchnopleuric membrane drive rightward torsion. A computational model based on realistic embryonic heart geometry is used to test this hypothesis. The behavior of the model is in reasonable agreement with available experimental data from control and perturbed embryos, offering support for our hypothesis. The results also suggest, however, that several other mechanisms contribute secondarily to normal looping, and we speculate that these mechanisms play backup roles when looping is perturbed. Finally, some outstanding questions are discussed for future study.

  15. Adaptive cerebellar spiking model embedded in the control loop: context switching and robustness against noise.

    Science.gov (United States)

    Luque, N R; Garrido, J A; Carrillo, R R; Tolu, S; Ros, E

    2011-10-01

    This work evaluates the capability of a spiking cerebellar model embedded in different loop architectures (recurrent, forward, and forward&recurrent) to control a robotic arm (three degrees of freedom) using a biologically-inspired approach. The implemented spiking network relies on synaptic plasticity (long-term potentiation and long-term depression) to adapt and cope with perturbations in the manipulation scenario: changes in dynamics and kinematics of the simulated robot. Furthermore, the effect of several degrees of noise in the cerebellar input pathway (mossy fibers) was assessed depending on the employed control architecture. The implemented cerebellar model managed to adapt in the three control architectures to different dynamics and kinematics providing corrective actions for more accurate movements. According to the obtained results, coupling both control architectures (forward&recurrent) provides benefits of the two of them and leads to a higher robustness against noise.

  16. Protective effect of lactobacillus acidophilus and isomaltooligosaccharide on intestinal mucosal barriers in rat models of antibiotic-associated diarrhea

    International Nuclear Information System (INIS)

    Du Dan; Fang Lichao; Chen Bingbo; Wei Hong

    2008-01-01

    Objective: To investigate the protective effect of synbiotics combined lactobacillus acidophilus and iso-malto-oligosaccharide (IMO) on intestinal mucosal barriers in rat models of antibiotic-associated diarrhea(AAD). Methods: Rat models of AAD were prepared with lincomycin gavage for 5 days. The synbiotics was orally administered to the AAD rats daily at three different strengths for 7 days. The intestinal flora and intestinal mucus SIgA levels were determined on d6, d9 and d13. The histopathological changes of ileal mucosa were studied on d13. Results: In the prepared AAD model rats (on d6) there were lower intestinal mucus SIgA levels and intestinal flora disorders were demonstrated. The intestinal floras of the rats administering synbiotics were readjusted to the similar pattern of healthy rats with bacterial translocation corrected on d13 and the levels of SIgA were not significantly different from of the control (P>0.05). The histopathological picture was basically normal in the treated models on d13. Conclusion: The synbiotics combined lactobacillus acidophilus and isomaltooligosaccharide possessed good protective effect on the intestinal mucosal barrier in lincomycin induced rat models of AAD. (authors)

  17. Dislocation loop formation in model FeCrAl alloys after neutron irradiation below 1 dpa

    Science.gov (United States)

    Field, Kevin G.; Briggs, Samuel A.; Sridharan, Kumar; Yamamoto, Yukinori; Howard, Richard H.

    2017-11-01

    FeCrAl alloys with varying compositions and microstructures are under consideration for accident-tolerant fuel cladding, but limited details exist on dislocation loop formation and growth for this class of alloys under neutron irradiation. Four model FeCrAl alloys with chromium contents ranging from 10.01 to 17.51 wt % and aluminum contents of 4.78 to 2.93 wt % were neutron irradiated to doses of 0.3-0.8 displacements per atom (dpa) at temperatures of 335-355 °C. On-zone STEM imaging revealed a mixed population of black dots and larger dislocation loops with either a / 2 〈 111 〉 or a 〈 100 〉 Burgers vectors. Weak composition dependencies were observed and varied depending on whether the defect size, number density, or ratio of defect types was of interest. Results were found to mirror those of previous studies on FeCrAl and FeCr alloys irradiated under similar conditions, although distinct differences exist.

  18. Natural Circulation High Pressure Loop Dynamics Around Operating Point, Tests and Modelling With Retran 02

    International Nuclear Information System (INIS)

    Masriera, N.A; Doval, A.S; Mazufri, C.M

    2000-01-01

    The Natural Circulation High Pressure Loop (CAPCN) reproduces in scale all the one-dimensional thermal-hydraulic phenomena occurring in the primary loop of CAREM-25 reactor.It plays an important role in the qualification process of calculating computer codes.This facility demanded to develop several technological solutions in order to achieve the measuring and control quality required by that process.This engineering and experimental development allowed completing the first stage of dynamic tests during 1998.The trends of recorded data were systematically evaluated in terms of the deviations of main variables in response to different perturbations.By this analysis a group of eight transients was selected, providing a Minimum Representative Set (MRS) of dynamic tests, allowing the evaluation of all dynamic phenomena.Each of these transients was simulated with RETRAN-02, using a spreadsheet to facilitate the consistent elaboration and modification of input files.Comparing measured data and computer simulations, it may be concluded that it is possible to reproduce the dynamic response of all the transients with a level of approximation quite homogeneous and generally acceptable.It is possible to identify the detailed physical models that fit better the dynamic phenomena, and which of the limitations of RETRAN code are more relevant

  19. Noise-shaping all-digital phase-locked loops modeling, simulation, analysis and design

    CERN Document Server

    Brandonisio, Francesco

    2014-01-01

    This book presents a novel approach to the analysis and design of all-digital phase-locked loops (ADPLLs), technology widely used in wireless communication devices. The authors provide an overview of ADPLL architectures, time-to-digital converters (TDCs) and noise shaping. Realistic examples illustrate how to analyze and simulate phase noise in the presence of sigma-delta modulation and time-to-digital conversion. Readers will gain a deep understanding of ADPLLs and the central role played by noise-shaping. A range of ADPLL and TDC architectures are presented in unified manner. Analytical and simulation tools are discussed in detail. Matlab code is included that can be reused to design, simulate and analyze the ADPLL architectures that are presented in the book.   • Discusses in detail a wide range of all-digital phase-locked loops architectures; • Presents a unified framework in which to model time-to-digital converters for ADPLLs; • Explains a procedure to predict and simulate phase noise in oscil...

  20. Amplification loop of the inflammatory process is induced by P2X7R activation in intestinal epithelial cells in response to neutrophil transepithelial migration.

    Science.gov (United States)

    Cesaro, Annabelle; Brest, Patrick; Hofman, Véronique; Hébuterne, Xavier; Wildman, Scott; Ferrua, Bernard; Marchetti, Sandrine; Doglio, Alain; Vouret-Craviari, Valérie; Galland, Franck; Naquet, Philippe; Mograbi, Baharia; Unwin, Robert; Hofman, Paul

    2010-07-01

    Inflammatory bowel diseases (IBD) are characterized during their active phase by polymorphonuclear leukocyte (PMNL) transepithelial migration. The efflux of PMNL into the mucosa is associated with the production of proinflammatory cytokines and the release of ATP from damaged and necrotic cells. The expression and function of purinergic P2X(7) receptor (P2X(7)R) in intestinal epithelial cells (IEC) and its potential role in the "cross talk" between IEC and PMNL have not been explored. The aims of the present study were 1) to examine P2X(7)R expression in IEC (T84 cells) and in human intestinal biopsies; 2) to detect any changes in P2X(7)R expression in T84 cells during PMNL transepithelial migration, and during the active and quiescent phases of IBD; and 3) to test whether P2X(7)R stimulation in T84 monolayers can induce caspase-1 activation and IL-1beta release by IEC. We found that a functional ATP-sensitive P2X(7)R is constitutively expressed at the apical surface of IEC T84 cells. PMNL transmigration regulates dynamically P2X(7)R expression and alters its distribution from the apical to basolateral surface of IEC during the early phase of PMNL transepithelial migration in vitro. P2X(7)R expression was weak in intestinal biopsies obtained during the active phase of IBD. We show that activation of epithelial P2X(7)R is mandatory for PMNL-induced caspase-1 activation and IL-1beta release by IEC. Overall, these changes in P2X(7)R function may serve to tailor the intensity of the inflammatory response and to prevent IL-1beta overproduction and inflammatory disease.

  1. The Metabolic Inhibition Model Which Predicts the Intestinal Absorbability and Metabolizability of Drug: Theory and Experiment

    Directory of Open Access Journals (Sweden)

    Mizuma Takashi

    1998-01-01

    Full Text Available The intestinal absorption of analgesic peptides (leucine enkephalin and kyotorphin and modified peptides in rat were studied. Although these peptides were not absorbed, the absorbability (absorption clearance of these peptides were increased in the presence of peptidase inhibitors. In order to kinetically analyze these phenomena, we proposed the metabolic inhibition model, which incorporated the metabolic clearance (metabolizability with the absorption clearance. Metabolic activity was determined with intestinal homogenates. The higher the metabolic clearance was, the lower was the absorption clearance. The relationships between the absorption clearance and the metabolic clearance of the experimental data as well as of the theoretical values were hyperbolic. This model predicted the maximum absorption clearances of cellobiose-coupled leucine enkephalin (0.654 &mgr;l/min/cm and kyotorphin (0.247 &mgr;l/min/cm. Details of the experimental methods are described.

  2. Preterm infant gut microbiota affects intestinal epithelial development in a humanized microbiome gnotobiotic mouse model.

    Science.gov (United States)

    Yu, Yueyue; Lu, Lei; Sun, Jun; Petrof, Elaine O; Claud, Erika C

    2016-09-01

    Development of the infant small intestine is influenced by bacterial colonization. To promote establishment of optimal microbial communities in preterm infants, knowledge of the beneficial functions of the early gut microbiota on intestinal development is needed. The purpose of this study was to investigate the impact of early preterm infant microbiota on host gut development using a gnotobiotic mouse model. Histological assessment of intestinal development was performed. The differentiation of four epithelial cell lineages (enterocytes, goblet cells, Paneth cells, enteroendocrine cells) and tight junction (TJ) formation was examined. Using weight gain as a surrogate marker for health, we found that early microbiota from a preterm infant with normal weight gain (MPI-H) induced increased villus height and crypt depth, increased cell proliferation, increased numbers of goblet cells and Paneth cells, and enhanced TJs compared with the changes induced by early microbiota from a poor weight gain preterm infant (MPI-L). Laser capture microdissection (LCM) plus qRT-PCR further revealed, in MPI-H mice, a higher expression of stem cell marker Lgr5 and Paneth cell markers Lyz1 and Cryptdin5 in crypt populations, along with higher expression of the goblet cell and mature enterocyte marker Muc3 in villus populations. In contrast, MPI-L microbiota failed to induce the aforementioned changes and presented intestinal characteristics comparable to a germ-free host. Our data demonstrate that microbial communities have differential effects on intestinal development. Future studies to identify pioneer settlers in neonatal microbial communities necessary to induce maturation may provide new insights for preterm infant microbial ecosystem therapeutics. Copyright © 2016 the American Physiological Society.

  3. Mice overexpressing CD97 in intestinal epithelial cells provide a unique model for mammalian postnatal intestinal cylindrical growth

    NARCIS (Netherlands)

    Aust, Gabriela; Kerner, Christiane; Gonsior, Susann; Sittig, Doreen; Schneider, Hartmut; Buske, Peter; Scholz, Markus; Dietrich, Norman; Oldenburg, Sindy; Karpus, Olga N.; Galle, Jörg; Amasheh, Salah; Hamann, Jörg

    2013-01-01

    Postnatal enlargement of the mammalian intestine comprises cylindrical and luminal growth, associated with crypt fission and crypt/villus hyperplasia, respectively, which subsequently predominate before and after weaning. The bipartite adhesion G protein-coupled receptor CD97 shows an expression

  4. A reduced fidelity model for the rotary chemical looping combustion reactor

    KAUST Repository

    Iloeje, Chukwunwike O.

    2017-01-11

    The rotary chemical looping combustion reactor has great potential for efficient integration with CO capture-enabled energy conversion systems. In earlier studies, we described a one-dimensional rotary reactor model, and used it to demonstrate the feasibility of continuous reactor operation. Though this detailed model provides a high resolution representation of the rotary reactor performance, it is too computationally expensive for studies that require multiple model evaluations. Specifically, it is not ideal for system-level studies where the reactor is a single component in an energy conversion system. In this study, we present a reduced fidelity model (RFM) of the rotary reactor that reduces computational cost and determines an optimal combination of variables that satisfy reactor design requirements. Simulation results for copper, nickel and iron-based oxygen carriers show a four-order of magnitude reduction in simulation time, and reasonable prediction accuracy. Deviations from the detailed reference model predictions range from 3% to 20%, depending on oxygen carrier type and operating conditions. This study also demonstrates how the reduced model can be modified to deal with both optimization and design oriented problems. A parametric study using the reduced model is then applied to analyze the sensitivity of the optimal reactor design to changes in selected operating and kinetic parameters. These studies show that temperature and activation energy have a greater impact on optimal geometry than parameters like pressure or feed fuel fraction for the selected oxygen carrier materials.

  5. Selection of ESBL-Producing E. coli in a Mouse Intestinal Colonization Model.

    Science.gov (United States)

    Hertz, Frederik Boëtius; Nielsen, Karen Leth; Frimodt-Møller, Niels

    2018-01-01

    Asymptomatic human carriage of antimicrobially drug-resistant pathogens prior to infection is increasing worldwide. Further investigation into the role of this fecal reservoir is important for combatting the increasing antimicrobial resistance problems. Additionally, the damage on the intestinal microflora due to antimicrobial treatment is still not fully understood. Animal models are powerful tools to investigate bacterial colonization subsequent to antibiotic treatment. In this chapter we present a mouse-intestinal colonization model designed to investigate how antibiotics select for an ESBL-producing E. coli isolate. The model can be used to study how antibiotics with varying effect on the intestinal flora promote the establishment of the multidrug-resistant E. coli. Colonization is successfully investigated by sampling and culturing stool during the days following administration of antibiotics. Following culturing, a precise identification of the bacterial strain found in mice feces is applied to ensure that the isolate found is in fact identical to the strain used for inoculation. For this purpose random amplified of polymorphic DNA (RAPD) PCR specifically developed for E. coli is applied. This method allows us to distinguish E. coli with more than 99.95% genome similarity using a duplex PCR method.

  6. Scintigraphic visualization of bacterial translocation in experimental strangulated intestinal obstruction

    International Nuclear Information System (INIS)

    Galeev, Yu.M.; Popov, M.V.; Salato, O.V.; Lishmanov, Yu.B.; Grigorev, E.G.; Aparcin, K.A.

    2009-01-01

    The purpose of this study was to obtain scintigraphic images depicting translocation of 99m Tc-labelled Escherichia coli bacteria through the intestinal barrier and to quantify this process using methods of nuclear medicine. Thirty male Wistar rats (including 20 rats with modelled strangulated intestinal obstruction and 10 healthy rats) were used for bacterial scintigraphy. 99m Tc-labelled E. coli bacteria ( 99m Ts-E. coli) with an activity of 7.4-11.1 MBq were administered into a section of the small intestine. Scintigraphic visualization of bacterial translocation into organs and tissues of laboratory animals was recorded in dynamic (240 min) and static (15 min) modes. The number of labelled bacteria, which migrated through the intestinal barrier, was quantified by calculating the translocation index (TI). Control indicated no translocation of 99m Ts-E. coli administered into the intestine through the parietes of the small intestine's distal part in healthy animals. Animals with strangulated obstruction demonstrated different migration strength and routes of labelled bacteria from strangulated and superior to strangulation sections of the small intestine. 99m Ts-E. coli migrated from the strangulated loop into the peritoneal cavity later causing systemic bacteraemia through peritoneal resorption. The section of the small intestine, which was superior to the strangulation, demonstrated migration of labelled bacteria first into the portal and then into the systemic circulation. The strangulated section of the small intestine was the main source of bacteria dissemination since the number of labelled bacteria, which migrated from this section significantly, exceeded that of the area superior to the strangulation section of the small intestine (p = 0.0003). Bacterial scintigraphy demonstrated the possibility of visualizing migration routes of labelled bacteria and quantifying their translocation through the intestinal barrier. This approach to study bacterial

  7. A Mixed Integer Linear Programming Model for the Design of Remanufacturing Closed–loop Supply Chain Network

    Directory of Open Access Journals (Sweden)

    Mbarek Elbounjimi

    2015-11-01

    Full Text Available Closed-loop supply chain network design is a critical issue due to its impact on both economic and environmental performances of the supply chain. In this paper, we address the problem of designing a multi-echelon, multi-product and capacitated closed-loop supply chain network. First, a mixed-integer linear programming formulation is developed to maximize the total profit. The main contribution of the proposed model is addressing two economic viability issues of closed-loop supply chain. The first issue is the collection of sufficient quantity of end-of-life products are assured by retailers against an acquisition price. The second issue is exploiting the benefits of colocation of forward facilities and reverse facilities. The presented model is solved by LINGO for some test problems. Computational results and sensitivity analysis are conducted to show the performance of the proposed model.

  8. Effect of Da-Cheng-Qi Decoction on Pancreatitis-Associated Intestinal Dysmotility in Patients and in Rat Models

    Directory of Open Access Journals (Sweden)

    Jianlei Zhao

    2015-01-01

    Full Text Available The impairment of intestinal motility and related infectious complications are the predominant clinical phenomenon in patients with severe acute pancreatitis (SAP. We aimed to investigate the effects of Da-Cheng-Qi decoction (DCQD on the gastrointestinal injury in SAP patients and the potential mechanism involved in rats. DCQD was enema administered to 70 patients for 7 days in West China Hospital. Mortality and organ failure during admission were observed and blood samples for laboratory analysis were collected. We also experimentally examined plasma inflammatory cytokines in rat serum and carried the morphometric studies of the gut. Intestinal propulsion index and serum and tissue vasoactive intestinal peptide (VIP were also detected. Though DCQD did not affect the overall incidence of organ failure, it shortened the average time of paralytic intestinal obstruction and decreased the morbidity of infectious complications in patients with SAP. Compared with untreated rats, the DCQD lowered the levels of proinflammatory cytokine and decreased the mean pathological intestinal lesion scores. The VIP level in intestinal tissue or serum in DCQD group was obviously lowered and intestinal propulsion index was significantly improved. In conclusion, DCQD has good effect on pancreatitis-associated intestinal dysmotility in patients and in rat models.

  9. Effect of da-cheng-qi decoction on pancreatitis-associated intestinal dysmotility in patients and in rat models.

    Science.gov (United States)

    Zhao, Jianlei; Zhong, Cejun; He, Zhiyu; Chen, Guangyuan; Tang, Wenfu

    2015-01-01

    The impairment of intestinal motility and related infectious complications are the predominant clinical phenomenon in patients with severe acute pancreatitis (SAP). We aimed to investigate the effects of Da-Cheng-Qi decoction (DCQD) on the gastrointestinal injury in SAP patients and the potential mechanism involved in rats. DCQD was enema administered to 70 patients for 7 days in West China Hospital. Mortality and organ failure during admission were observed and blood samples for laboratory analysis were collected. We also experimentally examined plasma inflammatory cytokines in rat serum and carried the morphometric studies of the gut. Intestinal propulsion index and serum and tissue vasoactive intestinal peptide (VIP) were also detected. Though DCQD did not affect the overall incidence of organ failure, it shortened the average time of paralytic intestinal obstruction and decreased the morbidity of infectious complications in patients with SAP. Compared with untreated rats, the DCQD lowered the levels of proinflammatory cytokine and decreased the mean pathological intestinal lesion scores. The VIP level in intestinal tissue or serum in DCQD group was obviously lowered and intestinal propulsion index was significantly improved. In conclusion, DCQD has good effect on pancreatitis-associated intestinal dysmotility in patients and in rat models.

  10. Progressive Depletion of Rough Endoplasmic Reticulum in Epithelial Cells of the Small Intestine in Monosodium Glutamate Mice Model of Obesity

    Directory of Open Access Journals (Sweden)

    Kazuhiko Nakadate

    2016-01-01

    Full Text Available Chronic obesity is a known risk factor for metabolic syndrome. However, little is known about pathological changes in the small intestine associated with chronic obesity. This study investigated cellular and subcellular level changes in the small intestine of obese mice. In this study, a mouse model of obesity was established by early postnatal administration of monosodium glutamate. Changes in body weight were monitored, and pathological changes in the small intestine were evaluated using hematoxylin-eosin and Nissl staining and light and electron microscopy. Consequently, obese mice were significantly heavier compared with controls from 9 weeks of age. Villi in the small intestine of obese mice were elongated and thinned. There was reduced hematoxylin staining in the epithelium of the small intestine of obese mice. Electron microscopy revealed a significant decrease in and shortening of rough endoplasmic reticulum in epithelial cells of the small intestine of obese mice compared with normal mice. The decrease in rough endoplasmic reticulum in the small intestine epithelial cells of obese mice indicates that obesity starting in childhood influences various functions of the small intestine, such as protein synthesis, and could impair both the defense mechanism against invasion of pathogenic microbes and nutritional absorption.

  11. On the significance of the noise model for the performance of a linear MPC in closed-loop operation

    DEFF Research Database (Denmark)

    Hagdrup, Morten; Boiroux, Dimitri; Mahmoudi, Zeinab

    2016-01-01

    models typically means less parameters to identify. Systematic tuning of such controllers is discussed. Simulation studies are conducted for linear time-invariant systems showing that choosing a noise model of low order is beneficial for closed-loop performance. (C) 2016, IFAC (International Federation...

  12. CDP-choline reduces severity of intestinal injury in a neonatal rat model of necrotizing enterocolitis.

    Science.gov (United States)

    Cetinkaya, Merih; Cansev, Mehmet; Cekmez, Ferhat; Tayman, Cuneyt; Canpolat, Fuat Emre; Kafa, Ilker M; Uysal, Sema; Tunc, Turan; Sarici, S Umit

    2013-07-01

    Cytidine 5'-diphosphocholine (CDP-choline) is an endogenous intermediate in the biosynthesis of phosphatidylcholine, a contributor to the mucosal defense of the intestine. The aim of this study was to evaluate the possible cytoprotective effect of CDP-choline treatment on intestinal cell damage, membrane phospholipid content, inflammation, and apoptosis in a neonatal rat model of necrotizing enterocolitis (NEC). We divided a total of 30 newborn pups into three groups: control, NEC, and NEC + CDP-choline. We induced NEC by enteral formula feeding, exposure to hypoxia-hyperoxia, and cold stress. We administered CDP-choline intraperitoneally at 300 mg/kg/d for 3 d starting from the first day of life. We evaluated apoptosis macroscopically and histopathologically in combination with proinflammatory cytokines in the gut samples. Moreover, we determined membrane phospholipid levels as well as activities of xanthine oxidase, superoxide dismutase, glutathione peroxidase, and myeloperoxidase enzymes and the malondialdehyde content of intestinal tissue. Mean clinical sickness score, macroscopic gut assessment score, and intestinal injury score were significantly improved, whereas mean apoptosis score and caspase-3 levels were significantly reduced in pups in the NEC + CDP-choline group compared with the NEC group. Tissue proinflammatory cytokine (interleukin-1β, interleukin-6, and tumor necrosis factor-α) levels as well as tissue malondialdehyde content and myeloperoxidase activities were reduced, whereas glutathione peroxidase and superoxide dismutase activities were preserved in the NEC + CDP-choline group. In addition, NEC damage reduced intestinal tissue membrane phospholipids, whereas CDP-choline significantly enhanced total phospholipid and phosphatidylcholine levels. Long-term follow-up in additional experiments revealed increased body weight, decreased clinical sickness scores, and enhanced survival in CDP-choline-receiving versus saline-receiving pups with NEC

  13. Numerical Modeling of an Integrated Vehicle Fluids System Loop for Pressurizing a Cryogenic Tank

    Science.gov (United States)

    LeClair, A. C.; Hedayat, A.; Majumdar, A. K.

    2017-01-01

    This paper presents a numerical model of the pressurization loop of the Integrated Vehicle Fluids (IVF) system using the Generalized Fluid System Simulation Program (GFSSP). The IVF propulsion system, being developed by United Launch Alliance to reduce system weight and enhance reliability, uses boiloff propellants to drive thrusters for the reaction control system as well as to run internal combustion engines to develop power and drive compressors to pressurize propellant tanks. NASA Marshall Space Flight Center (MSFC) conducted tests to verify the functioning of the IVF system using a flight-like tank. GFSSP, a finite volume based flow network analysis software developed at MSFC, has been used to support the test program. This paper presents the simulation of three different test series, comparison of numerical prediction and test data and a novel method of presenting data in a dimensionless form. The paper also presents a methodology of implementing a compressor map in a system level code.

  14. Modeling Open-Loop MEMS Tunneling Accelerometer Based on Circular Plate

    Directory of Open Access Journals (Sweden)

    Hossein Jodat Kordlar

    2007-04-01

    Full Text Available In this paper open-loop MEMS tunneling accelerometer was modeled based on a clamped micro circular plate with a tip tunneling at its centre. Mechanical behavior of the micro plate was studied deriving governing equation based on classic Kirchhoff thin plate theory and it was discretized using Galerkin method. Dynamic response of the proposed accelerometer due to step and harmonic external excitation was studied and the magnitude of the applied acceleration was identified by measuring of the changing of tunneling current. Obtained results show that the proposed tunneling accelerometer very sensitive and it can be measure acceleration with very high resolution but very small gap of tip tunneling limit the range of measurable acceleration.

  15. A study of digital gyro compensation loops. [data conversion routines and breadboard models

    Science.gov (United States)

    1975-01-01

    The feasibility is discussed of replacing existing state-of-the-art analog gyro compensation loops with digital computations. This was accomplished by designing appropriate compensation loops for the dry turned TDF gyro, selecting appropriate data conversion and processing techniques and algorithms, and breadboarding the design for laboratory evaluation. A breadboard design was established in which one axis of a Teledyne turned-gimbal TDF gyro was caged digitally while the other was caged using conventional analog electronics. The digital loop was designed analytically to closely resemble the analog loop in performance. The breadboard was subjected to various static and dynamic tests in order to establish the relative stability characteristics and frequency responses of the digital and analog loops. Several variations of the digital loop configuration were evaluated. The results were favorable.

  16. In Vitro Model Simulating Gastro-Intestinal Digestion in the Pediatric Population (Neonates and Young Infants)

    DEFF Research Database (Denmark)

    Kamstrup, Danna; Berthelsen, Ragna; Sassene, Philip Jonas

    2017-01-01

    , it is important to simulate the gastro-intestinal conditions and processes the drug will encounter upon oral administration. When a drug is administered in the fed state, which is commonly the case for neonates, as they are typically fed every 3 h, the digestion of the milk will affect the composition...... of the fluid available for drug dissolution/solubilization. Therefore, in order to predict the solubilized amount of drug available for absorption, an in vitro model simulating digestion in the gastro-intestinal tract should be utilized. In order to simulate the digestion process and the drug solubilization...... taking place in vivo, the following aspects should be considered; physiologically relevant media, media volume, use of physiological enzymes in proper amounts, as well as correct pH and addition of relevant co-factors, e.g., bile salts and co-enzymes. Furthermore, physiological transit times...

  17. Williamson Fluid Model for the Peristaltic Flow of Chyme in Small Intestine

    Directory of Open Access Journals (Sweden)

    Sohail Nadeem

    2012-01-01

    Full Text Available Mathematical model for the peristaltic flow of chyme in small intestine along with inserted endoscope is considered. Here, chyme is treated as Williamson fluid, and the flow is considered between the annular region formed by two concentric tubes (i.e., outer tube as small intestine and inner tube as endoscope. Flow is induced by two sinusoidal peristaltic waves of different wave lengths, traveling down the intestinal wall with the same speed. The governing equations of Williamson fluid in cylindrical coordinates have been modeled. The resulting nonlinear momentum equations are simplified using long wavelength and low Reynolds number approximations. The resulting problem is solved using regular perturbation method in terms of a variant of Weissenberg number We. The numerical solution of the problem is also computed by using shooting method, and comparison of results of both solutions for velocity field is presented. The expressions for axial velocity, frictional force, pressure rise, stream function, and axial pressure gradient are obtained, and the effects of various emerging parameters on the flow characteristics are illustrated graphically. Furthermore, the streamlines pattern is plotted, and it is observed that trapping occurs, and the size of the trapped bolus varies with varying embedded flow parameters.

  18. Tuning supersymmetric models at the LHC: A comparative analysis at two-loop level

    CERN Document Server

    Ghilencea, D M; Park, M

    2012-01-01

    We provide a comparative study of the fine tuning amount (Delta) at the two-loop leading log level in supersymmetric models commonly used in SUSY searches at the LHC. These are the constrained MSSM (CMSSM), non-universal Higgs masses models (NUHM1, NUHM2), non-universal gaugino masses model (NUGM) and GUT related gaugino masses models (NUGMd). Two definitions of the fine tuning are used, the first (Delta_{max}) measures maximal fine-tuning wrt individual parameters while the second (Delta_q) adds their contribution in "quadrature". As a direct result of two theoretical constraints (the EW minimum conditions), fine tuning (Delta_q) emerges as a suppressing factor (effective prior) of the averaged likelihood (under the priors), under the integral of the global probability of measuring the data (Bayesian evidence p(D)). For each model, there is little difference between Delta_q, Delta_{max} in the region allowed by the data, with similar behaviour as functions of the Higgs, gluino, stop mass or SUSY scale (m_{su...

  19. Application of neural models as controllers in mobile robot velocity control loop

    Science.gov (United States)

    Cerkala, Jakub; Jadlovska, Anna

    2017-01-01

    This paper presents the application of an inverse neural models used as controllers in comparison to classical PI controllers for velocity tracking control task used in two-wheel, differentially driven mobile robot. The PI controller synthesis is based on linear approximation of actuators with equivalent load. In order to obtain relevant datasets for training of feed-forward multi-layer perceptron based neural network used as neural model, the mathematical model of mobile robot, that combines its kinematic and dynamic properties such as chassis dimensions, center of gravity offset, friction and actuator parameters is used. Neural models are trained off-line to act as an inverse dynamics of DC motors with particular load using data collected in simulation experiment for motor input voltage step changes within bounded operating area. The performances of PI controllers versus inverse neural models in mobile robot internal velocity control loops are demonstrated and compared in simulation experiment of navigation control task for line segment motion in plane.

  20. Analysis of the intestinal lumen microbiota in an animal model of colorectal cancer.

    Directory of Open Access Journals (Sweden)

    Qingchao Zhu

    Full Text Available Recent reports have suggested that multiple factors such as host genetics, environment and diet can promote the progression of healthy mucosa towards sporadic colorectal carcinoma. Accumulating evidence has additionally associated intestinal bacteria with disease initiation and progression. In order to examine and analyze the composition of gut microbiota in the absence of confounding influences, we have established an animal model of 1, 2-dimethylhydrazine (DMH-induced colon cancer. Using this model, we have performed pyrosequencing of the V3 region of the 16S rRNA genes in this study to determine the diversity and breadth of the intestinal microbial species. Our findings indicate that the microbial composition of the intestinal lumen differs significantly between control and tumor groups. The abundance of Firmicutes was elevated whereas the abundance of Bacteroidetes and Spirochetes was reduced in the lumen of CRC rats. Fusobacteria was not detected in any of the healthy rats and there was no significant difference in observed Proteobacteria species when comparing the bacterial communities between our two groups. Interestingly, the abundance of Proteobacteria was higher in CRC rats. At the genus level, Bacteroides exhibited a relatively higher abundance in CRC rats compared to controls (14.92% vs. 9.22%, p<0.001. Meanwhile, Prevotella (55.22% vs. 26.19%, Lactobacillus (3.71% vs. 2.32% and Treponema (3.04% vs. 2.43%, were found to be significantly more abundant in healthy rats than CRC rats (p<0.001, respectively. We also demonstrate a significant reduction of butyrate-producing bacteria such as Roseburia and Eubacterium in the gut microbiota of CRC rats. Furthermore, a significant increase in Desulfovibrio, Erysipelotrichaceae and Fusobacterium was also observed in the tumor group. A decrease in probiotic species such as Ruminococcus and Lactobacillus was likewise observed in the tumor group. Collectively, we can conclude that a significant

  1. Specific microbiome changes in a mouse model of parenteral nutrition associated liver injury and intestinal inflammation.

    Science.gov (United States)

    Harris, J Kirk; El Kasmi, Karim C; Anderson, Aimee L; Devereaux, Michael W; Fillon, Sophie A; Robertson, Charles E; Wagner, Brandie D; Stevens, Mark J; Pace, Norman R; Sokol, Ronald J

    2014-01-01

    Parenteral nutrition (PN) has been a life-saving treatment in infants intolerant of enteral feedings. However, PN is associated with liver injury (PN Associated Liver Injury: PNALI) in a significant number of PN-dependent infants. We have previously reported a novel PNALI mouse model in which PN infusion combined with intestinal injury results in liver injury. In this model, lipopolysaccharide activation of toll-like receptor 4 signaling, soy oil-derived plant sterols, and pro-inflammatory activation of Kupffer cells (KCs) played key roles. The objective of this study was to explore changes in the intestinal microbiome associated with PNALI. Microbiome analysis in the PNALI mouse identified specific alterations within colonic microbiota associated with PNALI and further association of these communities with the lipid composition of the PN solution. Intestinal inflammation or soy oil-based PN infusion alone (in the absence of enteral feeds) caused shifts within the gut microbiota. However, the combination resulted in accumulation of a specific taxon, Erysipelotrichaceae (23.8% vs. 1.7% in saline infused controls), in PNALI mice. Moreover, PNALI was markedly attenuated by enteral antibiotic treatment, which also was associated with significant reduction of Erysipelotrichaceae (0.6%) and a Gram-negative constituent, the S24-7 lineage of Bacteroidetes (53.5% in PNALI vs. 0.8%). Importantly, removal of soy oil based-lipid emulsion from the PN solution resulted in significant reduction of Erysipelotrichaceae as well as attenuation of PNALI. Finally, addition of soy-derived plant sterol (stigmasterol) to fish oil-based PN restored Erysipelotrichaceae abundance and PNALI. Soy oil-derived plant sterols and the associated specific bacterial groups in the colonic microbiota are associated with PNALI. Products from these bacteria may directly trigger activation of KCs and promote PNALI. Furthermore, the results indicate that lipid modification of PN solutions may alter

  2. Order α'(two-loop) equivalence of the string equations of motion and the σ-model Weyl invariance conditions

    International Nuclear Information System (INIS)

    Metsaev, R.R.; Tseytlin, A.A.

    1987-01-01

    We prove the on-shell equivalence of the order α' terms in the string effective equations (for the graviton, dilaton and the antisymmetric tensor) to the vanishing of the corresponding (two-loop) terms in the Weyl anomaly coefficients for the general bosonic σ-model. We first determine the α' term in the string effective action starting with the known expression for the 3- and 4-point string amplitudes. Then we compute the two-loop β-function in the general σ-model with the antisymmetric tensor coupling. Special emphasis is made on the renormalization scheme dependence of the β-function. Our result disagrees with the previously known one and cannot be manifestly expressed in terms of the generalized curvature for the connection with torsion. We also prove (to the order α' 2 ) that the parallelizable spaces are solutions of the string equations of motion and establish the complete 3-loop expression for the 'central charge' coefficient. (orig.)

  3. Enlarged symmetry algebras of spin chains, loop models, and S-matrices

    International Nuclear Information System (INIS)

    Read, N.; Saleur, H.

    2007-01-01

    The symmetry algebras of certain families of quantum spin chains are considered in detail. The simplest examples possess m states per site (m>=2), with nearest-neighbor interactions with U(m) symmetry, under which the sites transform alternately along the chain in the fundamental m and its conjugate representation m-bar. We find that these spin chains, even with arbitrary coefficients of these interactions, have a symmetry algebra A m much larger than U(m), which implies that the energy eigenstates fall into sectors that for open chains (i.e., free boundary conditions) can be labeled by j=0,1,...,L, for the 2L-site chain such that the degeneracies of all eigenvalues in the jth sector are generically the same and increase rapidly with j. For large j, these degeneracies are much larger than those that would be expected from the U(m) symmetry alone. The enlarged symmetry algebra A m (2L) consists of operators that commute in this space of states with the Temperley-Lieb algebra that is generated by the set of nearest-neighbor interaction terms; A m (2L) is not a Yangian. There are similar results for supersymmetric chains with gl(m+n|n) symmetry of nearest-neighbor interactions, and a richer representation structure for closed chains (i.e., periodic boundary conditions). The symmetries also apply to the loop models that can be obtained from the spin chains in a spacetime or transfer matrix picture. In the loop language, the symmetries arise because the loops cannot cross. We further define tensor products of representations (for the open chains) by joining chains end to end. The fusion rules for decomposing the tensor product of representations labeled j 1 and j 2 take the same form as the Clebsch-Gordan series for SU(2). This and other structures turn the symmetry algebra A m into a ribbon Hopf algebra, and we show that this is 'Morita equivalent' to the quantum group U q (sl 2 ) for m=q+q -1 . The open-chain results are extended to the cases vertical bar m vertical

  4. Phase-field Model for Interstitial Loop Growth Kinetics and Thermodynamic and Kinetic Models of Irradiated Fe-Cr Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yulan; Hu, Shenyang Y.; Sun, Xin; Khaleel, Mohammad A.

    2011-06-15

    Microstructure evolution kinetics in irradiated materials has strongly spatial correlation. For example, void and second phases prefer to nucleate and grow at pre-existing defects such as dislocations, grain boundaries, and cracks. Inhomogeneous microstructure evolution results in inhomogeneity of microstructure and thermo-mechanical properties. Therefore, the simulation capability for predicting three dimensional (3-D) microstructure evolution kinetics and its subsequent impact on material properties and performance is crucial for scientific design of advanced nuclear materials and optimal operation conditions in order to reduce uncertainty in operational and safety margins. Very recently the meso-scale phase-field (PF) method has been used to predict gas bubble evolution, void swelling, void lattice formation and void migration in irradiated materials,. Although most results of phase-field simulations are qualitative due to the lake of accurate thermodynamic and kinetic properties of defects, possible missing of important kinetic properties and processes, and the capability of current codes and computers for large time and length scale modeling, the simulations demonstrate that PF method is a promising simulation tool for predicting 3-D heterogeneous microstructure and property evolution, and providing microstructure evolution kinetics for higher scale level simulations of microstructure and property evolution such as mean field methods. This report consists of two parts. In part I, we will present a new phase-field model for predicting interstitial loop growth kinetics in irradiated materials. The effect of defect (vacancy/interstitial) generation, diffusion and recombination, sink strength, long-range elastic interaction, inhomogeneous and anisotropic mobility on microstructure evolution kinetics is taken into account in the model. The model is used to study the effect of elastic interaction on interstitial loop growth kinetics, the interstitial flux, and sink

  5. One-loop effective Lagrangian for a standard model with a heavy charged scalar singlet

    CERN Document Server

    Bilenky, S M; Bilenky, Mikhail; Santamaria, Arcadi

    1994-01-01

    We study several problems related to the construction and the use of effective Lagrangians by considering an extension of the standard model that includes a heavy scalar singlet coupled to the leptonic doublet. Starting from the full renormalizable model, we build an effective field theory by integrating out the heavy scalar. A local effective Lagrangian (up to operators of dimension six) is obtained by expanding the one-loop effective action in inverse powers of the heavy mass. This is done by matching some Green functions calculated with both the full and the effective theories. Using this simple example we study the renormalization of effective Lagrangians in general and discuss how they can be used to bound new physics. We also discuss the effective Lagrangian after spontaneous symmetry breaking, and the use of the standard model classical equations of motion to rewrite it in different forms. The final effective Lagrangian in the physical basis is well suited to the study of the phenomenology of the model...

  6. Theoretical Modeling and Simulation of Phase-Locked Loop (PLL for Clock Data Recovery (CDR

    Directory of Open Access Journals (Sweden)

    Zainab Mohamad Ashari

    2012-01-01

    Full Text Available Modern communication and computer systems require rapid (Gbps, efficient  and large bandwidth data transfers. Agressive scaling of digital integrated systems  allow buses and communication controller circuits to be integrated with the microprocessor on the same chip. The  Peripheral Component Interconnect Express (PCIe protocol handles all communcation between the central processing unit (CPU and hardware devices. PCIe buses require efficient clock data recovery circuits (CDR to recover clock signals embedded in data during transmission. This paper describes the theoretical modeling and simulation of a phase-locked loop (PLL used in a CDR circuit. A simple PLL architecture for a 5 GHz CDR circuit is proposed  and elaborated in this work. Simulations were carried out using a Hardware Description Language, Verilog-AMS. The effect of jitter on the proposed design is also simulated and evaluated in this work. It was found that the proposed design is robust against both input and VCO jitter.ABSTRAK: Sistem komunikasi dan komputer moden memerlukan pemindahan data yang cekap (Gbps, dan bandwidth yang besar. Pengecilan agresif menggunakan teknik sistem digital bersepadu membenarkan bas dan litar pengawal komunikasi disatukan dengan  mikroprocessor dalam cip yang sama. Protokol persisian komponen sambung tara ekspres (PCIe mengendalikan semua komunikasi antara unit pemprosesan pusat (CPU dan peranti perkakasan. Bas PCIe memerlukan litar jam pemulihan data (CDR yang cekap untuk mendapatkan kembali isyarat jam yang tertanam dalam data semasa transmisi. Karya ini menerangkan teori pemodelan dan simulasi gelung fasa terkunci (PLL untuk CDR. Rekabentuk 5 GHz PLL yang mudah telah dicadangkan dalm kertas kerja ini. Simulasi telah dijalankan menggunakan perisian verilog-AMS. Simulasi mengunnakan kesan ketar dalam reka bentuk yang dicadangkan telah dinilai. Reka bentuk yang dicadangkan terbukti teguh mengatasi ganguan ketar di input dan VCO.KEY WORDS

  7. Intestinal inflammatory myofibroblastic tumour

    African Journals Online (AJOL)

    abdominal X-ray of patients 1, 3 and 4 demonstrated dilated small bowel loops with fluid levels in keeping with intestinal ... myxoid/vascular pattern characterised by a variable admixture of capillary-calibre blood vessels, .... in the present study had a past history of abdominal trauma or surgery. Ancillary histopathological ...

  8. The role of intestinal endotoxemia in a rat model of aluminum neurotoxicity

    OpenAIRE

    Wang, Feng; Guo, Rui-Xia; Li, Wen-Xing; Yu, Bao-Feng; Han, Bai; Liu, Li-Xin; Han, De-Wu

    2017-01-01

    The present study aimed to investigate the effects of intestinal endotoxemia (IETM) in a rat model of aluminum neurotoxicity established by D-galactose and aluminum trichloride (AlCl3). Adult Wistar rats were administered D-galactose and AlCl3 to create the aluminum neurotoxicity model. The learning and memory abilities of the rats were subsequently observed using a Morris water maze test and the serum levels of lipopolysaccharide (LPS), tumor necrosis factor (TNF)-α, interleukin (IL)-1, diam...

  9. Resveratrol and curcumin as protective agents in an experimental rat model of intestinal ischemia and reperfusion.

    Science.gov (United States)

    Cucolas, Cristina; Daneasa, Alexandra Ioana; Olteanu, Diana; Decea, Nicoleta; Moldovan, Remus; Tabaran, Flaviu; Filip, Gabriela Adriana

    2016-05-30

    The aim of this study was to evaluate the protective effects of resveratrol and curcumin in an experimental rat model of intestinal ischemia-reperfusion (I/R). Forty-eight adult Wistar rats were used: 12 animals undergoing the sham surgery and 36 animals undergoing laparotomy, with 15 min of mesentric artery clamping. The animals from the latter group (n = 12) were pretreated, for 1 week, with vehicle (CTR), resveratrol (RES), and curcumin (CUR). After 1 h and 6 h of reperfusion, respectively, cyclooxigenase (COX)-2, mucin-1, E-cadherin, nuclear factor (NK)-κB expressions, and tumor necrosis factor related apoptosis-inducing ligand (TRAIL) were assessed in the small intestine. Oxidative stress markers were determined in tissue homogenate and serum, and histopathological analysis was performed. Pretreatment with RES decreased the expression of COX-2 and NF-κB at both intervals and increased E-cadherin (p < 0.05) and mucin-1 production after 1 h. CUR had a beneficial effect on COX-2, NF-κB, and E-cadherin expressions, both after 1 h and after 6 h (p < 0.0001). The two compounds increased TRAIL levels and had a protective effect on oxidative stress and histopathological lesions, both after 1 h and after 6 h. Our results suggested that RES and CUR had beneficial effects in intestinal I/R and may represent a promising option for complementary treatment of this pathological condition.

  10. Innovative Disease Model: Zebrafish as an In Vivo Platform for Intestinal Disorder and Tumors

    Directory of Open Access Journals (Sweden)

    Jeng-Wei Lu

    2017-09-01

    Full Text Available Colorectal cancer (CRC is one of the world’s most common cancers and is the second leading cause of cancer deaths, causing more than 50,000 estimated deaths each year. Several risk factors are highly associated with CRC, including being overweight, eating a diet high in red meat and over-processed meat, having a history of inflammatory bowel disease, and smoking. Previous zebrafish studies have demonstrated that multiple oncogenes and tumor suppressor genes can be regulated through genetic or epigenetic alterations. Zebrafish research has also revealed that the activation of carcinogenesis-associated signal pathways plays an important role in CRC. The biology of cancer, intestinal disorders caused by carcinogens, and the morphological patterns of tumors have been found to be highly similar between zebrafish and humans. Therefore, the zebrafish has become an important animal model for translational medical research. Several zebrafish models have been developed to elucidate the characteristics of gastrointestinal diseases. This review article focuses on zebrafish models that have been used to study human intestinal disorders and tumors, including models involving mutant and transgenic fish. We also report on xenograft models and chemically-induced enterocolitis. This review demonstrates that excellent zebrafish models can provide novel insights into the pathogenesis of gastrointestinal diseases and help facilitate the evaluation of novel anti-tumor drugs.

  11. Colitis promotes adaptation of an intestinal nematode: a Heligmosomoides polygyrus mouse model system.

    Directory of Open Access Journals (Sweden)

    Katarzyna Donskow-Łysoniewska

    Full Text Available The precise mechanism of the very effective therapeutic effect of gastrointestinal nematodes on some autoimmune diseases is not clearly understood and is currently being intensively investigated. Treatment with living helminths has been initiated to reverse intestinal immune-mediated diseases in humans. However, little attention has been paid to the phenotype of nematodes in the IBD-affected gut and the consequences of nematode adaptation. In the present study, exposure of Heligmosomoides polygyrus larvae to the changed cytokine milieu of the intestine during colitis reduced inflammation in an experimental model of dextran sulphate sodium (DSS- induced colitis, but increased nematode establishment in the moderate-responder BALB/c mouse strain. We used mass spectrometry in combination with two-dimensional Western blotting to determine changes in protein expression and changes in nematode antigens recognized by IgG1 in mice with colitis. We show that nematode larvae immunogenicity is changed by colitis as soon as 6 days post-infection; IgG1 did not recognize highly conserved proteins Lev-11 (isoform 1 of tropomyosin α1 chain, actin-4 isoform or FTT-2 isoform a (14-3-3 family protein. These results indicate that changes in the small intestine provoked by colitis directly influence the nematode proteome. The unrecognized proteins seem to be key antigenic epitopes able to induce protective immune responses. The proteome changes were associated with weak immune recognition and increased larval adaptation and worm growth, altered localization in the intestine and increased survival of males but reduced worm fecundity. In this report, the mechanisms influencing nematode survival and the consequences of changed immunogenicity that reflect the immune response at the site colonized by the parasite in mice with colitis are described. The results are relevant to the use of live parasites to ameliorate IBD.

  12. [Flow model of internal-loop granular sludge bed nitrifying reactor].

    Science.gov (United States)

    Lu, Gang; Zheng, Ping

    2003-11-01

    Internal-loop granular sludge bed nitrifying reactor is a new type of aerobic nitrifying equipment and has shown a good potential for nitrification. To study the flow pattern and construct the flow model, the tracer tests were performed using pulse stimulus-response technique. Based on the experimental results, the flow pattern in the settling section and the circulating section of reactor were analyzed by axial dispersion model and tank-in-series model, respectively. The dispersion number D/uL of 0.00148 in the settling section indicates that its flow pattern is similar to plug flow reactor (PFR), and the series number N of 1.021 in the circulating section indicates that its flow pattern is similar to continuously stirred tank reactor (CSTR). During steady state, the theoretic hydraulic retention time is 360 min, and the actual hydraulic retention time is 341.2 min. The percentage of dead space in the reactor is 5.22%, thereinto the dead space caused by biomass (db ) is 0.75 % and the hydraulic dead space (dh) is 4.47%, which shows that the structural performance of the reactor is excellent. Based on the experiments and analysis, a model of CSTR and PFR in series was constructed. The actual hydraulic retention time distribution of the reactor is in good agreement with the model predictions. Since the relative error between them is 8.56%, the model is accurate to describe the flow pattern. The results have laid a foundation for the kinetic model of the reactor and will be helpful for its design and operation.

  13. Physical evolution in loop quantum cosmology: The example of the vacuum Bianchi I model

    International Nuclear Information System (INIS)

    Martin-Benito, Mercedes; Marugan, Guillermo A. Mena; Pawlowski, Tomasz

    2009-01-01

    We use the vacuum Bianchi I model as an example to investigate the concept of physical evolution in loop quantum cosmology (LQC) in the absence of the massless scalar field which has been used so far in the literature as an internal time. In order to retrieve the system dynamics when no such a suitable clock field is present, we explore different constructions of families of unitarily related partial observables. These observables are parametrized, respectively, by: (i) one of the components of the densitized triad, and (ii) its conjugate momentum; each of them playing the role of an evolution parameter. Exploiting the properties of the considered example, we investigate in detail the domains of applicability of each construction. In both cases the observables possess a neat physical interpretation only in an approximate sense. However, whereas in case (i) such interpretation is reasonably accurate only for a portion of the evolution of the universe, in case (ii) it remains so during all the evolution (at least in the physically interesting cases). The constructed families of observables are next used to describe the evolution of the Bianchi I universe. The performed analysis confirms the robustness of the bounces, also in absence of matter fields, as well as the preservation of the semiclassicality through them. The concept of evolution studied here and the presented construction of observables are applicable to a wide class of models in LQC, including quantizations of the Bianchi I model obtained with other prescriptions for the improved dynamics.

  14. First step of the project for implementation of two non-symmetric cooling loops modeled by the ALMOD3 code

    International Nuclear Information System (INIS)

    Dominguez, L.; Camargo, C.T.M.

    1984-09-01

    The first step of the project for implementation of two non-symmetric cooling loops modeled by the ALMOD3 computer code is presented. This step consists of the introduction of a simplified model for simulating the steam generator. This model is the GEVAP computer code, integrant part of LOOP code, which simulates the primary coolant circuit of PWR nuclear power plants during transients. The ALMOD3 computer code has a model for the steam generator, called UTSG, which is very detailed. This model has spatial dependence, correlations for 2-phase flow, distinguished correlations for different heat transfer process. The GEVAP model has thermal equilibrium between phases (gaseous and liquid homogeneous mixture), no spatial dependence and uses only one generalized correlation to treat several heat transfer processes. (Author) [pt

  15. Hardware-in-the-Loop Modeling and Simulation Methods for Daylight Systems in Buildings

    Science.gov (United States)

    Mead, Alex Robert

    This dissertation introduces hardware-in-the-loop modeling and simulation techniques to the daylighting community, with specific application to complex fenestration systems. No such application of this class of techniques, optimally combining mathematical-modeling and physical-modeling experimentation, is known to the author previously in the literature. Daylighting systems in buildings have a large impact on both the energy usage of a building as well as the occupant experience within a space. As such, a renewed interest has been placed on designing and constructing buildings with an emphasis on daylighting in recent times as part of the "green movement.''. Within daylighting systems, a specific subclass of building envelope is receiving much attention: complex fenestration systems (CFSs). CFSs are unique as compared to regular fenestration systems (e.g. glazing) in the regard that they allow for non-specular transmission of daylight into a space. This non-specular nature can be leveraged by designers to "optimize'' the times of the day and the days of the year that daylight enters a space. Examples of CFSs include: Venetian blinds, woven fabric shades, and prismatic window coatings. In order to leverage the non-specular transmission properties of CFSs, however, engineering analysis techniques capable of faithfully representing the physics of these systems are needed. Traditionally, the analysis techniques available to the daylighting community fall broadly into three classes: simplified techniques, mathematical-modeling and simulation, and physical-modeling and experimentation. Simplified techniques use "rules-of-thumb'' heuristics to provide insights for simple daylighting systems. Mathematical-modeling and simulation use complex numerical models to provide more detailed insights into system performance. Finally, physical-models can be instrumented and excited using artificial and natural light sources to provide performance insight into a daylighting system

  16. Improved capacity to evaluate changes in intestinal mucosal surface area using mathematical modeling.

    Science.gov (United States)

    Greig, Chasen J; Cowles, Robert A

    2017-07-01

    Quantification of intestinal mucosal growth typically relies on morphometric parameters, commonly villus height, as a surrogate for presumed changes in mucosal surface area (MSA). We hypothesized that using mathematical modeling based on multiple unique measurements would improve discrimination of the effects of interventions on MSA compared to standard measures. To determine the ability of mathematical modeling to resolve differences in MSA, a mouse model with enhanced serotonin (5HT) signaling known to stimulate mucosal growth was used. 5-HT signaling is potentiated by targeting the serotonin reuptake transporter (SERT) molecule. Selective serotonin reuptake inhibitor-treated wild-type (WT-SSRI), SERT-knockout (SERTKO), and wild-type C57Bl/6 (WT) mice were used. Distal ileal sections were H&E-stained. Villus height (VH), width (VW), crypt width (CW), and bowel diameter were used to calculate surface area enlargement factor (SEF) and MSA. VH alone for SERTKO and SSRI was significantly increased compared to WT, without a difference between SERTKO and WT-SSRI. VW and CW were significantly decreased for both SERTKO and WT-SSRI compared to WT, and VW for WT-SSRI was also decreased compared to SERTKO. These changes increased SEF and MSA for SERTKO and WT-SSRI compared to WT. Additionally, SEF and MSA were significantly increased for WT-SSRI compared to SERTKO. Mathematical modeling provides a valuable tool for differentiating changes in intestinal MSA. This more comprehensive assessment of surface area does not appear to correlate linearly with standard morphometric measures and represents a more comprehensive method for discriminating between therapies aimed at increasing functional intestinal mucosa. © 2017 Wiley Periodicals, Inc.

  17. Hidden attractors in dynamical models of phase-locked loop circuits: Limitations of simulation in MATLAB and SPICE

    Science.gov (United States)

    N. V., Kuznetsov; G. A., Leonov; M. V., Yuldashev; R. V., Yuldashev

    2017-10-01

    During recent years it has been shown that hidden oscillations, whose basin of attraction does not overlap with small neighborhoods of equilibria, may significantly complicate simulation of dynamical models, lead to unreliable results and wrong conclusions, and cause serious damage in drilling systems, aircrafts control systems, electromechanical systems, and other applications. This article provides a survey of various phase-locked loop based circuits (used in satellite navigation systems, optical, and digital communication), where such difficulties take place in MATLAB and SPICE. Considered examples can be used for testing other phase-locked loop based circuits and simulation tools, and motivate the development and application of rigorous analytical methods for the global analysis of phase-locked loop based circuits.

  18. A New Open-Loop Fiber Optic Gyro Error Compensation Method Based on Angular Velocity Error Modeling

    OpenAIRE

    Zhang, Yanshun; Guo, Yajing; Li, Chunyu; Wang, Yixin; Wang, Zhanqing

    2015-01-01

    With the open-loop fiber optic gyro (OFOG) model, output voltage and angular velocity can effectively compensate OFOG errors. However, the model cannot reflect the characteristics of OFOG errors well when it comes to pretty large dynamic angular velocities. This paper puts forward a modeling scheme with OFOG output voltage  and temperature  as the input variables and angular velocity error  as the output variable. Firstly, the angular ve...

  19. Hymenaea stigonocarpa Mart. ex Hayne: A tropical medicinal plant with intestinal anti-inflammatory activity in TNBS model of intestinal inflammation in rats.

    Science.gov (United States)

    Orsi, Patrícia Rodrigues; Seito, Leonardo Noboru; Di Stasi, Luiz Claudio

    2014-01-01

    Stem bark and fruit pulp of Hymenaea stigonocarpa Mart ex. Hayne (Fabaceae) has been popularly used to treat inflammation and gastrointestinal diseases including ulcers, diarrhea and gastric pain. The aim of this study was to investigate the intestinal anti-inflammatory activity of a methanol extract derived from the stem bark and diet with fruit pulp of Hymenaea stigonocarpa in the TNBS model of intestinal inflammation in rats. The intestinal anti-inflammatory activity of stem bark extract (100, 200 and 400mg/kg) and fruit pulp (10% and 5% in diet) was measured against the intestinal inflammatory process induced by TNBS (trinitrobenzesulphonic acid) in rats. The protective effects were evaluated as follows: evaluation of intestinal damage (damage score, extension of lesion, colon weight/length ratio), incidence of diarrhea and adherence to adjacent organs, colon glutathione (GSH) and malondialdehyde (MDA) contents, myeloperoxidase (MPO) and alkaline phosphatase (AP) activities. In addition, in vitro studies on lipid peroxidation in rat brain membranes and phytochemical profile were performed with both stem bark and fruit pulp. Treatment with 100, 200 and 400mg/kg of stem bark extract and 10% fruit pulp flour showed protective effects in the TNBS-induced colon damage, which was related to inhibition of MPO and AP activities, reduction in colon MDA content, and counteraction of GSH depletion induced by inflammatory process. A concentration-dependent inhibitory effect on the lipid peroxidation in rat brain membranes for stem bark and fruit pulp was determined, with an IC50 value of 5.25 ± 0.23 μg/mL and 27.33 ± 0.09 μg/mL, respectively. Similar phytochemical composition was observed in fruit and stem bark, including mainly flavonoids, condensed tannins and terpenes. Stem bark extract and fruit pulp flour of Hymenaea stigonocarpa prevented TNBS-induced colonic damage in rats and this protective effect were associated to an improvement of intestinal oxidative

  20. Dynamic model of heat and mass transfer in an unsaturated porous wick of capillary pumped loop

    International Nuclear Information System (INIS)

    Boubaker, Riadh; Platel, Vincent; Berges, Alexis; Bancelin, Mathieu; Hannezo, Edouard

    2015-01-01

    This paper presents a numerical study of a Capillary Pumped Loop evaporator. A two-dimensional unsteady mathematical model of a flat evaporator is developed to simulate heat and mass transfer in unsaturated porous wick with phase change. The liquid–vapor phase change inside the porous wick is described by Langmuir's law. The governing equations are solved by the Finite Element Method. The results are presented then for a sintered nickel wick and methanol as a working fluid. The heat flux required to the transition from the all-liquid wick to the vapor–liquid wick is calculated. The dynamic and thermodynamic behavior of the working fluid in the capillary structure are discussed in this paper. - Highlights: • We develop an unsteady model of two phase flow in porous wick with phase change. • We describe the heat and mass transfer inside the CPL evaporator. • We study the dynamic growth of the vapor pocket inside the porous wick. • The transition from the all liquid wick to the vapor–liquid wick is examined. • Porous wick with large porosity and conductivity reduces the parasitic flux

  1. Intestinal Conditioning After Cardiac Arrest: The Use of Normothermic Extracorporeal Membrane Oxygenation in the Non-Heart-Beating Animal Model.

    Science.gov (United States)

    Guo, Mingxiao; Yao, Danhua; Li, Linlin; Lu, Chunlei; Li, Yousheng; Li, Jieshou

    2016-08-01

    The effect of normothermic extracorporeal membrane oxygenation (NECMO) on small bowel preservation in a clinically relevant large animal model of expected donation after cardiac death (eDCD) was evaluated. Thirty domestic crossbred donor pigs were divided into five groups. The first group served as the live donation (LD) group, the second group served as the donation after cardiac death (DCD) group, and the remaining were further assigned into three subgroups: E1 group (1 h NECMO support), E3 group (3 h NECMO support), and E5 group (5 h NECMO support). Pathology, electron microscopy, energy metabolism, cell apoptosis, and tight junction (TJ) protein expression level of intestinal mucosa and the level of plasma d-lactic acid were evaluated in normal, cardiac death and at the end of extracorporeal support, respectively. The mean arterial pressure and PaO2 were maintained over 60 and 267 mm Hg during NECMO support, respectively. One hour of extracorporeal support could improve the energy status in intestines of the DCD group. Although the histologic damage and apoptosis of the E1 group had no significant difference with those of the LD and DCD groups (P > 0.05), the levels of intestinal mucosa TJ protein decreased (P intestinal mucosa damage and intestinal permeability gradually increased, as well as the content of adenosine triphosphate in intestinal mucosa. The normothermic extracorporeal support for 1 h in DCD is beneficial for improving the energy status and viability of the bowel. However, the integrity of intestinal mucosa was destroyed gradually as extracorporeal support time went by. And the activation of intestinal epithelial apoptosis and hyperoxia might be the factors that lead to intestinal mucosa injury. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  2. Roles of amino acids in preventing and treating intestinal diseases: recent studies with pig models.

    Science.gov (United States)

    Liu, Yulan; Wang, Xiuying; Hou, Yongqing; Yin, Yulong; Qiu, Yinsheng; Wu, Guoyao; Hu, Chien-An Andy

    2017-08-01

    Animal models are needed to study and understand a human complex disease. Because of their similarities in anatomy, structure, physiology, and pathophysiology, the pig has proven its usefulness in studying human gastrointestinal diseases, such as inflammatory bowel disease, ischemia/reperfusion injury, diarrhea, and cancer. To understand the pathogenesis of these diseases, a number of experimental models generated in pigs are available, for example, through surgical manipulation, chemical induction, microbial infection, and genetic engineering. Our interests have been using amino acids as therapeutics in pig and human disease models. Amino acids not only play an important role in protein biosynthesis, but also exert significant physiological effects in regulating immunity, anti-oxidation, redox regulation, energy metabolism, signal transduction, and animal behavior. Recent studies in pigs have shown that specific dietary amino acids can improve intestinal integrity and function under normal and pathological conditions that protect the host from different diseases. In this review, we summarize several pig models in intestinal diseases and how amino acids can be used as therapeutics in treating pig and human diseases.

  3. Effects of design variables predicted by a steady - state thermal performance analysis model of a loop heat pipe

    International Nuclear Information System (INIS)

    Jung, Eui Guk; Boo, Joon Hong

    2008-01-01

    This study deals with a mathematical modeling for the steady-state temperature characteristics of an entire loop heat pipe. The lumped layer model was applied to each node for temperature analysis. The flat type evaporator and condenser in the model had planar dimensions of 40 mm (W) x 50 mm (L). The wick material was a sintered metal and the working fluid was methanol. The molecular kinetic theory was employed to model the phase change phenomena in the evaporator and the condenser. Liquid-vapor interface configuration was expressed by the thin film theories available in the literature. Effects of design factors of loop heat pipe on the thermal performance were investigated by the modeling proposed in this study

  4. Modeling and performance analysis of a closed-loop supply chain using first-order hybrid Petri nets

    Directory of Open Access Journals (Sweden)

    Imane Outmal

    2016-05-01

    Full Text Available Green or closed-loop supply chain had been the focus of many manufacturers during the last decade. The application of closed-loop supply chain in today’s manufacturing is not only due to growing environmental concerns and the recognition of its benefits in reducing greenhouse gas emissions, energy consumption, and meeting a more strict environmental regulations but it also offers economic competitive advantages if appropriately managed. First-order hybrid Petri nets represent a powerful graphical and mathematical formalism to map and analyze the dynamics of complex systems such as closed-loop supply chain networks. This article aims at illustrating the use of first-order hybrid Petri nets to model a closed-loop supply chain network and evaluate its operational, financial, and environmental performance measures under different management policies. Actual data from auto manufacturer in the United States are used to validate network’s performance under both tactical and strategic decision-making, namely, (1 tactical decision—production policies: increase of recovered versus new components and (2 strategic decision—closed-loop supply chain network structure: manufacturer internal recovery process or recovery process done by a third-party collection and recovery center. The work presented in this article is an extension of the use of first-order hybrid Petri nets as a modeling and performance analysis tool from supply chain to closed-loop supply chain. The modularity property of first-order hybrid Petri nets has been used in the modeling process, and the simulation and analysis of the modeled network are done in MATLAB® environment. The results of the experiments depict that first-order hybrid Petri nets are a powerful modeling and analysis formalism for closed-loop supply chain networks and can be further used as an efficient decision-making tool at both tactical and strategic levels. Unlike other researches on modeling supply chain

  5. Intestinal bacterial overgrowth includes potential pathogens in the carbohydrate overload models of equine acute laminitis.

    Science.gov (United States)

    Onishi, Janet C; Park, Joong-Wook; Prado, Julio; Eades, Susan C; Mirza, Mustajab H; Fugaro, Michael N; Häggblom, Max M; Reinemeyer, Craig R

    2012-10-12

    Carbohydrate overload models of equine acute laminitis are used to study the development of lameness. It is hypothesized that a diet-induced shift in cecal bacterial communities contributes to the development of the pro-inflammatory state that progresses to laminar failure. It is proposed that vasoactive amines, protease activators and endotoxin, all bacterial derived bioactive metabolites, play a role in disease development. Questions regarding the oral bioavailability of many of the bacterial derived bioactive metabolites remain. This study evaluates the possibility that a carbohydrate-induced overgrowth of potentially pathogenic cecal bacteria occurs and that bacterial translocation contributes toward the development of the pro-inflammatory state. Two groups of mixed-breed horses were used, those with laminitis induced by cornstarch (n=6) or oligofructan (n=6) and non-laminitic controls (n=8). Cecal fluid and tissue homogenates of extra-intestinal sites including the laminae were used to enumerate Gram-negative and -positive bacteria. Horses that developed Obel grade2 lameness, revealed a significant overgrowth of potentially pathogenic Gram-positive and Gram-negative intestinal bacteria within the cecal fluid. Although colonization of extra-intestinal sites with potentially pathogenic bacteria was not detected, results of this study indicate that cecal/colonic lymphadenopathy and eosinophilia develop in horses progressing to lameness. It is hypothesized that the pro-inflammatory state in carbohydrate overload models of equine acute laminitis is driven by an immune response to the rapid overgrowth of Gram-positive and Gram-negative cecal bacterial communities in the gut. Further equine research is indicated to study the immunological response, involving the lymphatic system that develops in the model. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. Characterization of the withdrawal phase in a swine controlled intestinal donation after circulatory death model.

    Science.gov (United States)

    Guo, Mingxiao; Li, Linlin; Lu, Chunlei

    2014-10-04

    Transplantation of donation after cardiac death (DCD) intestine has higher rates of organ failure and complications. Fortunately, this is less grievous in a subclass of DCD called controlled (CDCD), those with irreversible but incomplete brain injury. The aim of the paper is to establish a CDCD porcine model which is closely mimicking human CDCD scenario, and investigate the physiologic changes from withdrawal of ventilatory support to circulatory arrest. Ten domestic crossbred pigs were anesthetized and ventilated with room air. Once all baseline data was taken, atracurium besilate (0.9 mg/kg, 3×ED95) was administered and the ventilator was discontinued while the animal was under deep anesthesia to establish the porcine CDCD model. Meanwhile, heparin (150~200 U/kg) was administered after discontinuation of the ventilator. The time to death and the changes of arterial blood gases and hemodynamic parameters were monitored every 5 minutes until circulatory arrest. In addition, histopathology, ultrastructures (via electron microscope) and expression of tight junction proteins of intestinal mucosa were observed at the baseline and the time of death. The mean time to death was approximately (21.8±3.12 min. Within 5 minutes of removal of the ventilator, there was a hyperdynamic period. Systolic blood pressure and heart rate quickly increased to 118.5±10.4 mmHg and 108.2±4.94 bpm, respectively. Blood pressure and heart rate then reduced rapidly until circulatory arrest. Moreover, the PaO2 quickly dropped to 17.4±3.13 mmHg, the blood gases throughout the apneic time showed a rapid hypercapnia and acidosis. In addition, warm ischemia damaged intestinal mucosa and reduced TJ proteins expression. A new swine CDCD model, simulating three stages of "withdrawal of ventilation, systemic anticoagulation and determination of death", which closely mimics the human DCD scenario and can thus be used in studies related to organ transplantation, was successfully established.

  7. Sacral nerve stimulation enhances early intestinal mucosal repair following mucosal injury in a pig model.

    Science.gov (United States)

    Brégeon, Jérémy; Coron, Emmanuel; Da Silva, Anna Christina Cordeiro; Jaulin, Julie; Aubert, Philippe; Chevalier, Julien; Vergnolle, Nathalie; Meurette, Guillaume; Neunlist, Michel

    2016-08-01

    Reducing intestinal epithelial barrier (IEB) dysfunctions is recognized as being of major therapeutic interest for various intestinal disorders. Sacral nerve stimulation (SNS) is known to reduce IEB permeability. Here, we report in a pig model that SNS enhances morphological and functional recovery of IEB following mucosal injury induced via 2,4,6-trinitrobenzenesulfonic acid. These effects are associated with an increased expression of tight junction proteins such as ZO-1 and FAK. These results establish that SNS enhances intestinal barrier repair in acute mucosal injury. They further set the scientific basis for future use of SNS as a complementary or alternative therapeutic option for the treatment of gut disorders with IEB dysfunctions such as inflammatory bowel diseases or irritable bowel syndrome. Intestinal epithelial barrier (IEB) dysfunctions, such as increased permeability or altered healing, are central to intestinal disorders. Sacral nerve stimulation (SNS) is known to reduce IEB permeability, but its ability to modulate IEB repair remains unknown. This study aimed to characterize the impact of SNS on mucosal repair following 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced lesions. Six pigs were stimulated by SNS 3 h prior to and 3 h after TNBS enema, while sham animals (n = 8) were not stimulated. The impact of SNS on mucosal changes was evaluated by combining in vivo imaging, histological and functional methods. Biochemical and transcriptomic approaches were used to analyse the IEB and mucosal inflammatory response. We observed that SNS enhanced the recovery from TNBS-induced increase in transcellular permeability. At 24 h, TNBS-induced alterations of mucosal morphology were significantly less in SNS compared with sham animals. SNS reduced TNBS-induced changes in ZO-1 expression and its epithelial pericellular distribution, and also increased pFAK/FAK expression compared with sham. Interestingly, SNS increased the mucosal density of neutrophils

  8. Pulled Polymer Loops as a Model for the Alignment of Meiotic Chromosomes

    Science.gov (United States)

    Lin, Yen Ting; Frömberg, Daniela; Huang, Wenwen; Delivani, Petrina; Chacón, Mariola; Tolić, Iva M.; Jülicher, Frank; Zaburdaev, Vasily

    2015-11-01

    During recombination, the DNA of parents exchange their genetic information to give rise to a genetically unique offspring. For recombination to occur, homologous chromosomes need to find each other and align with high precision. Fission yeast solves this problem by folding chromosomes in loops and pulling them through the viscous nucleoplasm. We propose a theory of pulled polymer loops to quantify the effect of drag forces on the alignment of chromosomes. We introduce an external force field to the concept of a Brownian bridge and thus solve for the statistics of loop configurations in space.

  9. Plant STAND P-loop NTPases: a current perspective of genome distribution, evolution, and function : Plant STAND P-loop NTPases: genomic organization, evolution, and molecular mechanism models contribute broadly to plant pathogen defense.

    Science.gov (United States)

    Arya, Preeti; Acharya, Vishal

    2018-02-01

    STAND P-loop NTPase is the common weapon used by plant and other organisms from all three kingdoms of life to defend themselves against pathogen invasion. The purpose of this study is to review comprehensively the latest finding of plant STAND P-loop NTPase related to their genomic distribution, evolution, and their mechanism of action. Earlier, the plant STAND P-loop NTPase known to be comprised of only NBS-LRRs/AP-ATPase/NB-ARC ATPase. However, recent finding suggests that genome of early green plants comprised of two types of STAND P-loop NTPases: (1) mammalian NACHT NTPases and (2) NBS-LRRs. Moreover, YchF (unconventional G protein and members of P-loop NTPase) subfamily has been reported to be exceptionally involved in biotic stress (in case of Oryza sativa), thereby a novel member of STAND P-loop NTPase in green plants. The lineage-specific expansion and genome duplication events are responsible for abundance of plant STAND P-loop NTPases; where "moderate tandem and low segmental duplication" trajectory followed in majority of plant species with few exception (equal contribution of tandem and segmental duplication). Since the past decades, systematic research is being investigated into NBS-LRR function supported the direct recognition of pathogen or pathogen effectors by the latest models proposed via 'integrated decoy' or 'sensor domains' model. Here, we integrate the recently published findings together with the previous literature on the genomic distribution, evolution, and distinct models proposed for functional molecular mechanism of plant STAND P-loop NTPases.

  10. One-loop radiative correction to the triple Higgs coupling in the Higgs singlet model

    Directory of Open Access Journals (Sweden)

    Shi-Ping He

    2017-01-01

    Full Text Available Though the 125 GeV Higgs boson is consistent with the standard model (SM prediction until now, the triple Higgs coupling can deviate from the SM value in the physics beyond the SM (BSM. In this paper, the radiative correction to the triple Higgs coupling is calculated in the minimal extension of the SM by adding a real gauge singlet scalar. In this model there are two scalars h and H and both of them are mixing states of the doublet and singlet. Provided that the mixing angle is set to be zero, namely the SM limit, h is the pure left-over of the doublet and its behavior is the same as that of the SM at the tree level. However the loop corrections can alter h-related couplings. In this SM limit case, the effect of the singlet H may show up in the h-related couplings, especially the triple h coupling. Our numerical results show that the deviation is sizable. For λΦS=1 (see text for the parameter definition, the deviation δhhh(1 can be 40%. For λΦS=1.5, the δhhh(1 can reach 140%. The sizable radiative correction is mainly caused by three reasons: the magnitude of the coupling λΦS, light mass of the additional scalar and the threshold enhancement. The radiative corrections for the hVV, hff couplings are from the counter-terms, which are the universal correction in this model and always at O(1%. The hZZ coupling, which can be precisely measured, may be a complementarity to the triple h coupling to search for the BSM. In the optimal case, the triple h coupling is very sensitive to the BSM physics, and this model can be tested at future high luminosity hadron colliders and electron–positron colliders.

  11. In vitro enteroid-derived three-dimensional tissue model of human small intestinal epithelium with innate immune responses.

    Directory of Open Access Journals (Sweden)

    Ying Chen

    Full Text Available There is a need for functional in vitro 3D human intestine systems that can bridge the gap between conventional cell culture studies and human trials. The successful engineering in vitro of human intestinal tissues relies on the use of the appropriate cell sources, biomimetic scaffolds, and 3D culture conditions to support vital organ functions. We previously established a compartmentalized scaffold consisting of a hollow space within a porous bulk matrix, in which a functional and physiologically relevant intestinal epithelium system was generated using intestinal cell lines. In this study, we adopt the 3D scaffold system for the cultivation of stem cell-derived human small intestinal enteriods (HIEs to engineer an in vitro 3D model of a nonstransformed human small intestinal epithelium. Characterization of tissue properties revealed a mature HIE-derived epithelium displaying four major terminally differentiated epithelial cell types (enterocytes, Goblet cells, Paneth cells, enteroendocrine cells, with tight junction formation, microvilli polarization, digestive enzyme secretion, and low oxygen tension in the lumen. Moreover, the tissue model demonstrates significant antibacterial responses to E. coli infection, as evidenced by the significant upregulation of genes involved in the innate immune response. Importantly, many of these genes are activated in human patients with inflammatory bowel disease (IBD, implicating the potential application of the 3D stem-cell derived epithelium for the in vitro study of host-microbe-pathogen interplay and IBD pathogenesis.

  12. In vitro enteroid-derived three-dimensional tissue model of human small intestinal epithelium with innate immune responses.

    Science.gov (United States)

    Chen, Ying; Zhou, Wenda; Roh, Terrence; Estes, Mary K; Kaplan, David L

    2017-01-01

    There is a need for functional in vitro 3D human intestine systems that can bridge the gap between conventional cell culture studies and human trials. The successful engineering in vitro of human intestinal tissues relies on the use of the appropriate cell sources, biomimetic scaffolds, and 3D culture conditions to support vital organ functions. We previously established a compartmentalized scaffold consisting of a hollow space within a porous bulk matrix, in which a functional and physiologically relevant intestinal epithelium system was generated using intestinal cell lines. In this study, we adopt the 3D scaffold system for the cultivation of stem cell-derived human small intestinal enteriods (HIEs) to engineer an in vitro 3D model of a nonstransformed human small intestinal epithelium. Characterization of tissue properties revealed a mature HIE-derived epithelium displaying four major terminally differentiated epithelial cell types (enterocytes, Goblet cells, Paneth cells, enteroendocrine cells), with tight junction formation, microvilli polarization, digestive enzyme secretion, and low oxygen tension in the lumen. Moreover, the tissue model demonstrates significant antibacterial responses to E. coli infection, as evidenced by the significant upregulation of genes involved in the innate immune response. Importantly, many of these genes are activated in human patients with inflammatory bowel disease (IBD), implicating the potential application of the 3D stem-cell derived epithelium for the in vitro study of host-microbe-pathogen interplay and IBD pathogenesis.

  13. A mathematical model for the peristaltic flow of chyme movement in small intestine.

    Science.gov (United States)

    Tripathi, Dharmendra

    2011-10-01

    A mathematical model based on viscoelastic fluid (fractional Oldroyd-B model) flow is considered for the peristaltic flow of chyme in small intestine, which is assumed to be in the form of an inclined cylindrical tube. The peristaltic flow of chyme is modeled more realistically by assuming that the peristaltic rush wave is a sinusoidal wave, which propagates along the tube. The governing equations are simplified by making the assumptions of long wavelength and low Reynolds number. Analytical approximate solutions of problem are obtained by using homotopy analysis method and convergence of the obtained series solution is properly checked. For the realistic values of the emerging parameters such as fractional parameters, relaxation time, retardation time, Reynolds number, Froude number and inclination of tube, the numerical results for the pressure difference and the frictional force across one wavelength are computed and discussed the roles played by these parameters during the peristaltic flow. On the basis of this study, it is found that the first fractional parameter, relaxation time and Froude number resist the movement of chyme, while, the second fractional parameter, retardation time, Reynolds number and inclination of tube favour the movement of chyme through the small intestine during pumping. It is further revealed that size of trapped bolus reduces with increasing the amplitude ratio whereas it is unaltered with other parameters. Copyright © 2011 Elsevier Inc. All rights reserved.

  14. Model prodrugs designed for the intestinal peptide transporter. A synthetic approach for coupling of hydroxy-containing compounds to dipeptides

    DEFF Research Database (Denmark)

    Friedrichsen, G M; Nielsen, C U; Steffansen, B

    2001-01-01

    The human peptide transporter, hPepT1, situated in the small intestine, may be exploited to increase absorption of drugs or model drugs by attaching them to a dipeptide, which is recognised by hPepT1. A synthetic protocol for this kind of model prodrugs was developed, in which model drugs...

  15. Model prodrugs for the intestinal peptide transporter. a synthetic approach for coupling of hydroxy-containing compounds to dieptides

    DEFF Research Database (Denmark)

    Friedrichsen, G; Nielsen, Carsten Uhd; Steffansen, Bente

    2001-01-01

    The human peptide transporter, hPepT1, situated in the small intestine, may be exploited to increase absorption of drugs or model drugs by attaching them to a dipeptide, which is recognised by hPepT1. A synthetic protocol for this kind of model prodrugs was developed, in which model drugs...

  16. Effect of Ozone on Intestinal Epithelial Homeostasis in a Rat Model

    Directory of Open Access Journals (Sweden)

    Igor Sukhotnik

    2015-01-01

    Full Text Available Background: The positive effects of ozone therapy have been described in many gastrointestinal disorders. The mechanisms of this positive effect of ozone therapy are poorly understood. The purpose of the present study was to investigate whether the use of ozone may potentiate the gut intestinal mucosal homeostasis in a rat model. Methods: Adult rats weighing 250–280 g were randomly assigned to one of three experimental groups of 8 rats each: 1 Control rats were given 2 mL of water by gavage and intraperitoneally (IP for 5 days; 2 O3-PO rats were treated with 2 mL of ozone/oxygen mixture by gavage and 2 mL of water IP for 5 days; 3 O3-IP rats were treated with 2 mL of water by gavage and 2 mL of ozone/oxygen mixture IP for 5 days. Rats were sacrificed on day 6. Bowel and mucosal weight, mucosal DNA and protein, villus height and crypt depth, and cell proliferation and apoptosis were evaluated following sacrifice. Results: The group of O3-IP rats demonstrated a greater jejunal and ileal villus height and crypt depth, a greater enterocyte proliferation index in jejunum, and lower enterocyte apoptosis in ileum compared to control animals. Oral administration of the ozone/oxygen mixture resulted in a less significant effect on cell turnover. Conclusions: Treatment with an ozone/oxygen mixture stimulates intestinal cell turnover in a rat model. Intraperitoneal administration of ozone resulted in a more significant intestinal trophic effect than oral administration.

  17. Optimization of solvation models for predicting the structure of surface loops in proteins.

    Science.gov (United States)

    Das, B; Meirovitch, H

    2001-05-15

    A novel procedure for optimizing the atomic solvation parameters (ASPs) sigma(i) developed recently for cyclic peptides is extended to surface loops in proteins. The loop is free to move, whereas the protein template is held fixed in its X-ray structure. The energy is E(tot) = E(FF)(epsilon = nr) + summation operator sigma(i)A(i), where E(FF)(epsilon = nr) is the force-field energy of the loop-loop and loop-template interactions, epsilon = nr is a distance-dependent dielectric constant, and n is an additional parameter to be optimized. A(i) is the solvent-accessible surface area of atom i. The optimal sigma(i) and n are those for which the loop structure with the global minimum of E(tot)(n, sigma(i)) becomes the experimental X-ray structure. Thus, the ASPs depend on the force field and are optimized in the protein environment, unlike commonly used ASPs such as those of Wesson and Eisenberg (Protein Sci 1992;1:227-235). The latter are based on the free energy of transfer of small molecules from the gas phase to water and have been traditionally combined with various force fields without further calibration. We found that for loops the all-atom AMBER force field performed better than OPLS and CHARMM22. Two sets of ASPs [based on AMBER (n = 2)], optimized independently for loops 64-71 and 89-97 of ribonuclease A, were similar and thus enabled the definition of a best-fit set. All these ASPs were negative (hydrophilic), including those for carbon. Very good (i.e., small) root-mean-square-deviation values from the X-ray loop structure were obtained with the three sets of ASPs, suggesting that the best-fit set would be transferable to loops in other proteins as well. The structure of loop 13-24 is relatively stretched and was insensitive to the effect of the ASPs. Copyright 2001 Wiley-Liss, Inc.

  18. Extended Euler–Euler model for the simulation of a 1 MWth chemical–looping pilot plant

    International Nuclear Information System (INIS)

    Alobaid, Falah; Ohlemüller, Peter; Ströhle, Jochen; Epple, Bernd

    2015-01-01

    In chemical–looping combustion (CLC), the oxygen–carrier circulates between two interconnected fluidized beds. Experiments can provide substantial insight into the hydrodynamic behaviour of CLC, but are limited to the scale of the investigated pilot plant. Furthermore, the availability of detailed experimental information from pilot plants is difficult because of the lack of accessibility, the harsh environment and the costs of measuring devices. Computational fluid dynamics (CFD) offers a significant contribution to the direct measurements. A recent literature review shows that Euler–Euler CFD–based model has not yet been applied to chemical–looping combustion of coal. Therefore, a three–dimensional, transient simulation model for the fuel reactor of CLC has been developed. Besides the calculation of gas–solid flow, the model includes an accurate description of kinetic models for pyrolysis, heterogeneous reactions and related heat and mass transfer processes. The extended Euler–Euler/thermochemical reaction model is validated with measurements obtained from the world's second–largest CLC pilot plant (1 MW th ) erected at TU Darmstadt. The numerical results suggest that the pressure drop in the fuel reactor, the exiting flue gas composition as well as the solid fuel conversion can be predicted reasonably. The validated model is of relevance for further feasibility and scale–up studies of CLC. - Highlights: • First 3D numerical study based on Euler–Euler CFD model for coal chemical–looping combustion. • Experimental data obtained from 1 MW th chemical–looping pilot plant are used for model validation. • Good agreement between the numerical results and measurements. • Deviations were observed by the reason of underestimation the recirculated mass flow of oxygen–carrier.

  19. SURVIVAL OF MICROORGANISMS FROM MODERN PROBIOTICS IN MODEL CONDITIONS OF THE INTESTINE

    Directory of Open Access Journals (Sweden)

    Kabluchko TV

    2017-03-01

    Full Text Available Introduction. The staye of intestinal microflora affects the work of the whole organism. When composition of normal ibtestine microflora changes, its restoration is required. In our days a wide variety of probiotic drugs are available on the market which can be used to solve this problem. Most bacteria having probiotic properties represent the families Lactobacillus and Bifidobacterium, which have poor resistance to acidic content of the stomach and toxic effects of bile salts. Various studies have clearly shown that in a person with normal acidic and bile secretion, the lactobacilli and bifidobacteria are not detected after the passage through the duodenum, i.e., they perish before reaching the small intestines. In this study we compared the survival of different microorganisms which are contained in 9 probiotic drugs in a model of gastric and intestinal environments. Material and methods. In the laboratory of SI: “Mechnikov Institute Microbiology and Immunology, National Ukrainian Academy Medical Sciences" the in vitro experiments have been evaluated to test the ability of different probiotic bacteria which were contained in 9 probiotic drugs to survive the impact of the model environment of the stomach and duodenum. Bacillus coagulans persistence was evaluated under impact of simulated environment of the stomach and duodenum, it also was assessed by the quantity of CFU by incubation on culture medium. The following were studied: Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus reuteri, Lactobacillus casei, Lactobacillus plantarum, Lactobacillus bulgaricus, Bifidobacterium bifidum, Bifidobacterium longum , Bifidobacterium breve, Bifidobacterium infantis, Bifidobacterium animalis subsp. Lactis BB-12, Saccharomyces boulardii, Bacillus coagulans, Bacillus clausii, Enterococcus faecium. Microorganisms were incubated for 3 hours in a model environment of the stomach (pepsin 3 g / l, hydrochloric acid of 160 mmol / l, pH 2

  20. A new discrete dynamic model of ABA-induced stomatal closure predicts key feedback loops.

    Directory of Open Access Journals (Sweden)

    Réka Albert

    2017-09-01

    several predictions of the model with regard to reactive oxygen species, cytosolic Ca2+ (Ca2+c, and heterotrimeric G-protein signaling. We analyzed dynamics-determining positive and negative feedback loops, thereby elucidating the attractor (dynamic behavior repertoire of the system and the groups of nodes that determine each attractor. Based on this analysis, we predict the likely presence of a previously unrecognized feedback mechanism dependent on Ca2+c. This mechanism would provide model agreement with 10 additional experimental observations, for a validation rate of 85%. Our research underscores the importance of feedback regulation in generating robust and adaptable biological responses. The high validation rate of our model illustrates the advantages of discrete dynamic modeling for complex, nonlinear systems common in biology.

  1. A differential algebraic approach for the modeling of polycrystalline ferromagnetic hysteresis with minor loops and frequency dependence

    International Nuclear Information System (INIS)

    Wang, Dan; Wang, Linxiang; Melnik, Roderick

    2016-01-01

    In the current paper, a nonlinear differential algebraic approach is proposed for the modeling of hysteretic dynamics of polycrystalline ferromagnetic materials. The model is constructed by employing a phenomenological theory to the magnetization orientation switching. For the modeling of hysteresis in polycrystalline ferromagnetic materials, the single crystal model is applied to each magnetic domain along its own principal axis. The overall dynamics of the polycrystalline materials is obtained by taking a weighted combination of the dynamics of all magnetic domains. The weight function for the combination is taken as the distribution function of the principal axes. Numerical simulations are performed and comparisons with its experimental counterparts are presented. The hysteretic dynamics caused by orientation switching processes is accurately captured by the proposed model. Minor hysteresis loops associated with partial-amplitude loadings are also captured. Rate dependence of the hysteresis loops are inherently incorporated into the model due to its differential nature. - Highlights: • Predict the polycrystalline hysteresis effectively. • Sub hysteresis loop can be captured. • Frequency dependence is naturally included.

  2. A differential algebraic approach for the modeling of polycrystalline ferromagnetic hysteresis with minor loops and frequency dependence

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Dan [State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, 310027 Hangzhou (China); Wang, Linxiang, E-mail: wanglx236@zju.edu.cn [State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, 310027 Hangzhou (China); Melnik, Roderick [MS2Discovery Interdisciplinary Research Institute, Wilfrid Laurier University, Waterloo, ON, Canada N2L 3L5 (Canada)

    2016-07-15

    In the current paper, a nonlinear differential algebraic approach is proposed for the modeling of hysteretic dynamics of polycrystalline ferromagnetic materials. The model is constructed by employing a phenomenological theory to the magnetization orientation switching. For the modeling of hysteresis in polycrystalline ferromagnetic materials, the single crystal model is applied to each magnetic domain along its own principal axis. The overall dynamics of the polycrystalline materials is obtained by taking a weighted combination of the dynamics of all magnetic domains. The weight function for the combination is taken as the distribution function of the principal axes. Numerical simulations are performed and comparisons with its experimental counterparts are presented. The hysteretic dynamics caused by orientation switching processes is accurately captured by the proposed model. Minor hysteresis loops associated with partial-amplitude loadings are also captured. Rate dependence of the hysteresis loops are inherently incorporated into the model due to its differential nature. - Highlights: • Predict the polycrystalline hysteresis effectively. • Sub hysteresis loop can be captured. • Frequency dependence is naturally included.

  3. Late effects of intraoperative radiation therapy on retroperitoneal tissues, intestine, and bile duct in a large animal model

    Energy Technology Data Exchange (ETDEWEB)

    Sindelar, W.F.; Tepper, J.E.; Kinslla, T.J.; Barnes, M.; DeLuca, A.M.; Terrill, R.; Matthews, D.; Johnstone, P.A.S. [National Institutes of Health, Bethesda, MD (United States); Anderson, W.J. [Terre Haute Center for Medical Education, IN (United States); Bollinger, B.K. [National Naval Medical Center, Bethesda, MD (United States)

    1994-07-01

    The late histopathological effects of intraoperative radiotherapy (IORT) on retroperitoneal tissues, intestine, and bile duct were investigated in dogs. Fourteen adult foxhounds were subjected to laparotomy and varying doses (0-45 Gy) of IORT (11 MeV electrons) delivered to retroperitoneal tissues including the great vessels and ureters, to a loop of defunctionalized small bowel, or to the extrahepatic bile duct. One control animal received an aortic transection and reanastomosis at the time of laparotomy; another control received laparotomy alone. This paper describes the late effects of single-fraction IORT occurring 3-5 years following treatment. Dogs receiving IORT to the retroperitoneum through a 4 X 15 cm portal showed few gross or histologic abnormalities at 20 Gy. At doses ranging from 30-45 Gy, radiation changes in normal tissues were consistently observed. Retroperitoneal fibrosis with encasement of the ureters and great vessels developed at doses {ge}30 Gy. Radiation changes were present in the aorta and vena cava at doses {ge}40 Gy. A 30 Gy dog developed an in-field malignant osteosarcoma at 3 years which invaded the vertebral column and compressed the spinal cord. A 40 Gy animal developed obstruction of the right ureter with fatal septic hydronephrosis at 4 years. Animals receiving IORT through a 5 cm IORT portal to an upper abdominal field which included a defunctionalized loop of small bowel, showed few gross or histologic abnormalities at a dose of 20 Gy. At 30 Gy, hyaline degeneration of the intestinal muscularis layer of the bowel occurred. At a dose of 45 Gy, internal intestinal fistulae developed. One 30 Gy animal developed right ureteral obstruction and hydronephrosis at 5 years. A dog receiving 30 Gy IORT through a 5 cm portal to the extrahepatic bile duct showed diffuse fibrosis through the gastroduodenal ligament. These canine studies contribute to the area of late tissue tolerance to IORT. 7 refs., 3 figs., 5 tabs.

  4. Late effects of intraoperative radiation therapy on retroperitoneal tissues, intestine, and bile duct in a large animal model

    International Nuclear Information System (INIS)

    Sindelar, W.F.; Tepper, J.E.; Kinslla, T.J.; Barnes, M.; DeLuca, A.M.; Terrill, R.; Matthews, D.; Johnstone, P.A.S.; Anderson, W.J.; Bollinger, B.K.

    1994-01-01

    The late histopathological effects of intraoperative radiotherapy (IORT) on retroperitoneal tissues, intestine, and bile duct were investigated in dogs. Fourteen adult foxhounds were subjected to laparotomy and varying doses (0-45 Gy) of IORT (11 MeV electrons) delivered to retroperitoneal tissues including the great vessels and ureters, to a loop of defunctionalized small bowel, or to the extrahepatic bile duct. One control animal received an aortic transection and reanastomosis at the time of laparotomy; another control received laparotomy alone. This paper describes the late effects of single-fraction IORT occurring 3-5 years following treatment. Dogs receiving IORT to the retroperitoneum through a 4 X 15 cm portal showed few gross or histologic abnormalities at 20 Gy. At doses ranging from 30-45 Gy, radiation changes in normal tissues were consistently observed. Retroperitoneal fibrosis with encasement of the ureters and great vessels developed at doses ≥30 Gy. Radiation changes were present in the aorta and vena cava at doses ≥40 Gy. A 30 Gy dog developed an in-field malignant osteosarcoma at 3 years which invaded the vertebral column and compressed the spinal cord. A 40 Gy animal developed obstruction of the right ureter with fatal septic hydronephrosis at 4 years. Animals receiving IORT through a 5 cm IORT portal to an upper abdominal field which included a defunctionalized loop of small bowel, showed few gross or histologic abnormalities at a dose of 20 Gy. At 30 Gy, hyaline degeneration of the intestinal muscularis layer of the bowel occurred. At a dose of 45 Gy, internal intestinal fistulae developed. One 30 Gy animal developed right ureteral obstruction and hydronephrosis at 5 years. A dog receiving 30 Gy IORT through a 5 cm portal to the extrahepatic bile duct showed diffuse fibrosis through the gastroduodenal ligament. These canine studies contribute to the area of late tissue tolerance to IORT. 7 refs., 3 figs., 5 tabs

  5. Stem Cell-Derived Human Intestinal Organoids as an Infection Model for Rotaviruses

    Science.gov (United States)

    Finkbeiner, Stacy R.; Zeng, Xi-Lei; Utama, Budi; Atmar, Robert L.; Shroyer, Noah F.; Estes, Mary K.

    2012-01-01

    ABSTRACT Directed differentiation of stem cell lines into intestine-like tissue called induced human intestinal organoids (iHIOs) is now possible (J. R. Spence, C. N. Mayhew, S. A. Rankin, M. F. Kuhar, J. E. Vallance, K. Tolle, E. E. Hoskins, V. V. Kalinichenko, S. I. Wells, A. M. Zorn, N. F. Shroyer, and J. M. Wells, Nature 470:105-109, 2011). We tested iHIOs as a new model to cultivate and study fecal viruses. Protocols for infection of iHIOs with a laboratory strain of rotavirus, simian SA11, were developed. Proof-of-principle analyses showed that iHIOs support replication of a gastrointestinal virus, rotavirus, on the basis of detection of nonstructural viral proteins (nonstructural protein 4 [NSP4] and NSP2) by immunofluorescence, increased levels of viral RNA by quantitative reverse transcription-PCR (qRT-PCR), and production of infectious progeny virus. iHIOs were also shown to support replication of 12/13 clinical rotavirus isolates directly from stool samples. An unexpected finding was the detection of rotavirus infection not only in the epithelial cells but also in the mesenchymal cell population of the iHIOs. This work demonstrates that iHIOs offer a promising new model to study rotaviruses and other gastrointestinal viruses. PMID:22761392

  6. Modeling and Compensation Design for a Power Hardware-in-the-Loop Simulation of an AC Distribution System: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Prabakar, Kumaraguru [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Ainsworth, Nathan [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Pratt, Annabelle [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Baggu, Murali M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Hariri, Ali [Formerly NREL

    2017-10-06

    Power hardware-in-the-loop (PHIL) simulation, where actual hardware under text is coupled with a real-time digital model in closed loop, is a powerful tool for analyzing new methods of control for emerging distributed power systems. However, without careful design and compensation of the interface between the simulated and actual systems, PHIL simulations may exhibit instability and modeling inaccuracies. This paper addresses issues that arise in the PHIL simulation of a hardware battery inverter interfaced with a simulated distribution feeder. Both the stability and accuracy issues are modeled and characterized, and a methodology for design of PHIL interface compensation to ensure stability and accuracy is presented. The stability and accuracy of the resulting compensated PHIL simulation is then shown by experiment.

  7. Intrinsic myenteric denervation: a new model to increase the intestinal absorptive surface in short-bowel syndrome.

    Science.gov (United States)

    Garcia, S B; Kawasaky, M C; Silva, J C; Garcia-Rodrigues, A C; Borelli-Bovo, T J; Iglesias, A C; Zucoloto, S

    1999-08-01

    Short-bowel syndrome (SBS) is caused by resection of massive portions of the small intestine and is characterized by symptoms related to malabsorption, of which severe weight loss is the most apparent. Surgical treatments for SBS are not yet satisfactory. In rats, the myenteric denervation by benzalkonium chloride (BAC) leads to development of megaileum with visceral dilatation and mucosal hyperplasia and increases the intestinal transit time. Such operation in the remaining intestinal segment after massive small bowel resection could increase the duration of contact between luminal nutrients and ileal mucosal epithelium, and furthermore, it could increase the superficial area of the mucosa. Thus, our aim in this study was to evaluate the epithelial morphology and body weight changes of animals after intrinsic ileal denervation associated with extensive small intestine resection. Wistar rats were submitted to resection of 80% of small intestinal length (Group R). Another group (B) of animals also received topical serosal application of BAC 0.3%. Control animals were submitted to simulated surgery (Group C). Animals were weighed weekly and sacrificed after 90 days. Intestinal walls were collected for histological procedure and morphometry. At the end of the experimental period all groups showed weight increase, which was reduced in the R group (P < 0.01). Interestingly, the denervated Group B showed a marked increase in weight, similar to the control animals. Morphometric analysis of the mucosal layer area showed a major increase in mucosal surface area, mainly in Group B. Our results showed that the ileal intrinsic denervation associated with massive intestinal resection induced an increase in the superficial absorptive area and was able to improve the postsurgical conditions for the animals, with accentuated weight increase. This procedure may be a useful model for further studies related to the role of the enteric nervous system on intestinal adaptations after

  8. Suppressing epileptic activity in a neural mass model using a closed-loop proportional-integral controller

    Science.gov (United States)

    Wang, Junsong; Niebur, Ernst; Hu, Jinyu; Li, Xiaoli

    2016-01-01

    Closed-loop control is a promising deep brain stimulation (DBS) strategy that could be used to suppress high-amplitude epileptic activity. However, there are currently no analytical approaches to determine the stimulation parameters for effective and safe treatment protocols. Proportional-integral (PI) control is the most extensively used closed-loop control scheme in the field of control engineering because of its simple implementation and perfect performance. In this study, we took Jansen’s neural mass model (NMM) as a test bed to develop a PI-type closed-loop controller for suppressing epileptic activity. A graphical stability analysis method was employed to determine the stabilizing region of the PI controller in the control parameter space, which provided a theoretical guideline for the choice of the PI control parameters. Furthermore, we established the relationship between the parameters of the PI controller and the parameters of the NMM in the form of a stabilizing region, which provided insights into the mechanisms that may suppress epileptic activity in the NMM. The simulation results demonstrated the validity and effectiveness of the proposed closed-loop PI control scheme. PMID:27273563

  9. Intestinal Cancer

    Science.gov (United States)

    ... connects your stomach to your large intestine. Intestinal cancer is rare, but eating a high-fat diet ... increase your risk. Possible signs of small intestine cancer include Abdominal pain Weight loss for no reason ...

  10. Non-animal models of epithelial barriers (skin, intestine and lung) in research, industrial applications and regulatory toxicology.

    NARCIS (Netherlands)

    Gordon, S.; Daneshian, M.; Bouwstra, J.A.; Caloni, F.; Constant, S.; Davies, D.E.; Dandekar, G.; Guzman, C.A.; Fabian, E.; Haltner, E.; Hartung, T.; Hasiwa, N.; Hayden, P.; Kandarova, H.; Khare, S.; Krug, H.F.; Kneuer, C.; Leist, M.; Lian, G.; Marx, U.; Metzger, M.; Ott, K.; Prieto, P.; Roberts, M.S.; Roggen, E.L.; Tralau, T.; Braak, van den C.; Walles, H.; Lehr, C.M.

    2015-01-01

    Models of the outer epithelia of the human body - namely the skin, the intestine and the lung - have found valid applications in both research and industrial settings as attractive alternatives to animal testing. A variety of approaches to model these barriers are currently employed in such fields,

  11. Alkaline Phosphatase for the Prevention of Intestinal and Renal Injury in a Rat Model of Cardiopulmonary Bypass with Deep Hypothermic Circulatory Arrest

    Science.gov (United States)

    2017-09-01

    AWARD NUMBER: W81XWH-16-1-0090 TITLE: Alkaline Phosphatase for the Prevention of Intestinal and Renal Injury in a Rat Model of Cardiopulmonary...TYPE Annual 3. DATES COVERED 8/15/2016—8/14/2017 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Alkaline Phosphatase for the Prevention of Intestinal... prevention of intestinal and kidney injury after pediatric cardiopulmonary bypass with deep hypothermic circulatory arrest. In this model, we place 5-10kg

  12. A model to study intestinal and hepatic metabolism of propranolol in the dog.

    Science.gov (United States)

    Mills, P C; Siebert, G A; Roberts, M S

    2004-02-01

    A model to investigate hepatic drug uptake and metabolism in the dog was developed for this study. Catheters were placed in the portal and hepatic veins during exploratory laparotomy to collect pre- and posthepatic blood samples at defined intervals. Drug concentrations in the portal vein were taken to reflect intestinal uptake and metabolism of an p.o. administered drug (propranolol), while differences in drug and metabolite concentrations between portal and hepatic veins reflected hepatic uptake and metabolism. A significant difference in propranolol concentration between hepatic and portal veins confirmed a high hepatic extraction of this therapeutic agent in the dog. This technically uncomplicated model may be used experimentally or clinically to determine hepatic function and metabolism of drugs that may be administered during anaesthesia and surgery.

  13. Dephosphorylation of myo-inositol phosphates in the in vitro intestinal Caco-2 cell model.

    Science.gov (United States)

    Briviba, Karlis; Schollenberger, Margit; Rodehutscord, Markus; Greiner, Ralf

    2018-02-01

    Plant and microbial phytases present in raw materials can cause a dephosphorylation of phytate (myo-inositol hexakisphosphate) (InsP 6 )) during food processing resulting in a broad range of different myo-inositol phosphates such as pentakisphosphate (InsP 5 ) and tetrakisphosphate (InsP 4 ) in foods. Here, we investigated whether the human intestinal epithelium is able to dephosphorylate myo-inositol phosphates (InsP 6 , InsP 5 -, InsP 4 -, InsP 3 -isomers) using an in vitro model with differentiated human Caco-2 cells cultured on semipermeable inserts. Incubation of InsP 6 and an InsP 5 -isomer with cells for 3 h showed no dephosphorylation of both InsPs. Treatment of cells with a mixture of different InsP 4 -isomers, however, caused a formation of about 3.5% of an InsP 3 -isomer (Ins(1,5,6)P 3 ) and treatment with a mixture of different InsP 3 -isomers caused about 20% formation of InsP 2 -isomers, respectively. Thus, human intestinal cells can contribute to the dephosphorylation of myo-inositol phosphates of partly dephosphorylated forms such as InsP 3 and InsP 4 .

  14. Intestinal trefoil factor in treatment of neonatal necrotizing enterocolitis in the rat model.

    Science.gov (United States)

    Shi, Lei; Zhang, Bing-Hong; Yu, Hong-Gang; Yu, Jie-Ping; Xi, Juan-Li

    2007-01-01

    Neonatal necrotizing enterocolitis (NEC) is the most common gastrointestinal disease of premature infants. The role of cytokines and growth factors in the pathophysiology of NEC is not yet clearly defined. Among these factors, the intestinal trefoil factor (ITF) is known as cytoprotective to the gut. We studied the cytoprotective effect of trefoil factor in the 1-day-old Wistar rat pup model following hypoxic-ischemic cold stress. In the present study, thirty 1-day-old Wistar rat pups were randomly divided into three groups: Group 1, normal controls: Group 2, NEC; Group 3, NEC+ITF. Experimental NEC was induced by exposure to hypoxia for 60 s followed by cold stress at 4 degrees C for 10 min. The animals were euthanized at development of NEC, and at 96 h the intestinal tissue was processed and examined for histological changes of NEC. The pathological lesions indicated severe separation of the submucosa and lamina propria and tissue necrosis in Group 2, and slight submucosal and lamina propria separation in Group 3. There were no histopathological changes in the controls. The mean of histological grade of group 2 was 2.8 (range 2-4), and 1.2 (range 0-2) in group 3. A difference was found when the two groups were compared (P<0.05). ITF may provide a new way for the therapy of NEC in rats.

  15. Process modelling and techno-economic analysis of natural gas combined cycle integrated with calcium looping

    Directory of Open Access Journals (Sweden)

    Erans María

    2016-01-01

    Full Text Available Calcium looping (CaL is promising for large-scale CO2 capture in the power generation and industrial sectors due to the cheap sorbent used and the relatively low energy penalties achieved with this process. Because of the high operating temperatures the heat utilisation is a major advantage of the process, since a significant amount of power can be generated from it. However, this increases its complexity and capital costs. Therefore, not only the energy efficiency performance is important for these cycles, but also the capital costs must be taken into account, i.e. techno-economic analyses are required in order to determine which parameters and configurations are optimal to enhance technology viability in different integration scenarios. In this study the integration scenarios of CaL cycles and natural gas combined cycles (NGCC are explored. The process models of the NGCC and CaL capture plant are developed to explore the most promising scenarios for NGCC-CaL integration with regards to efficiency penalties. Two scenarios are analysed in detail, and show that the system with heat recovery steam generator (HRSG before and after the capture plant exhibited better performance of 49.1% efficiency compared with that of 45.7% when only one HRSG is located after the capture plant. However, the techno-economic analyses showed that the more energy efficient case, with two HRSGs, implies relatively higher cost of electricity (COE, 44.1€/MWh, when compared to that of the reference plant system (33.1€/MWh. The predicted cost of CO2 avoided for the case with two HRSGS is 29.3 €/ton CO2.

  16. Outpatient Closed-Loop Control with Unannounced Moderate Exercise in Adolescents Using Zone Model Predictive Control.

    Science.gov (United States)

    Huyett, Lauren M; Ly, Trang T; Forlenza, Gregory P; Reuschel-DiVirgilio, Suzette; Messer, Laurel H; Wadwa, R Paul; Gondhalekar, Ravi; Doyle, Francis J; Pinsker, Jordan E; Maahs, David M; Buckingham, Bruce A; Dassau, Eyal

    2017-06-01

    The artificial pancreas (AP) has the potential to improve glycemic control in adolescents. This article presents the first evaluation in adolescents of the Zone Model Predictive Control and Health Monitoring System (ZMPC+HMS) AP algorithms, and their first evaluation in a supervised outpatient setting with frequent exercise. Adolescents with type 1 diabetes underwent 3 days of closed-loop control (CLC) in a hotel setting with the ZMPC+HMS algorithms on the Diabetes Assistant platform. Subjects engaged in twice-daily exercise, including soccer, tennis, and bicycling. Meal size (unrestricted) was estimated and entered into the system by subjects to trigger a bolus, but exercise was not announced. Ten adolescents (11.9-17.7 years) completed 72 h of CLC, with data on 95 ± 14 h of sensor-augmented pump (SAP) therapy before CLC as a comparison to usual therapy. The percentage of time with continuous glucose monitor (CGM) 70-180 mg/dL was 71% ± 10% during CLC, compared to 57% ± 16% during SAP (P = 0.012). Nocturnal control during CLC was safe, with 0% (0%, 0.6%) of time with CGM 250 mg/dL (16% ± 14% during SAP). The system remained connected in CLC for 97% ± 2% of the total study time. No adverse events or severe hypoglycemia occurred. The use of the ZMPC+HMS algorithms is feasible in the adolescent outpatient environment and achieved significantly more time in the desired glycemic range than SAP in the face of unannounced exercise and large announced meal challenges.

  17. Study on the Operating Characteristics and System Modelling of Loop type Thermosyphon for Using Solar Thermal Energy

    International Nuclear Information System (INIS)

    Kang, Myeong Cheol

    1999-02-01

    Solar energy is one of the promising resources of renewable energy. It is of particular interest due to the energy shortage and environment pollution problems. Water heating by solar energy for domestic use is one of the most successful and feasible applications of solar energy. The thermosyphon SDHWS and the loop type thermosyphon systems are widely used for domestic hot water system. The loop type thermosyphon is a circulation device for transferring the heat produced at the evaporator area to the condenser area in the loop by a working fluid. The system has the advantage of high heat transfer rate. A phase change of the working fluid occurs at the evaporator section and the vapor is transported to the condenser by the density gradient. The loop type thermosyphon collector can be made of smaller area and has higher efficiency than the present thermosyphon SDHWS. In this study, the operating characteristics of various working fluids being used have been identified. The working fluids employed in the study were ethanol, water and a binary mixture of ethanol and water. The volume of working fluid used in this study were 30%, 40%, 50%, 60% and 70% of evaporator volume. An increased heat was applied with the increased volume of working fluid. It is observed that, in the thermosyphon with low volume of working fluid, such as 30% or 40%, the fluid was dried out. The average efficiency of the loop type thermosyphon was 46% with high solar irradiation and 43% with low irradiation. The flow pattern and mechanism of the heat transfer were identified through this study. Flow patterns of the binary mixture working fluid were also investigated, and the patterns were recorded in the camera. The system parameters were calculated using the thermal performance data. Modelling of the system was carried out using PSTAR method and TRNSYS program

  18. A Collection-Distribution Center Location and Allocation Optimization Model in Closed-Loop Supply Chain for Chinese Beer Industry

    OpenAIRE

    Kai Kang; Xiaoyu Wang; Yanfang Ma

    2017-01-01

    Recycling waste products is an environmental-friendly activity that can result in manufacturing cost saving and economic efficiency improving. In the beer industry, recycling bottles can reduce manufacturing cost and the industry’s carbon footprint. This paper presents a model for a collection-distribution center location and allocation problem in a closed-loop supply chain for the beer industry under a fuzzy random environment, in which the objectives are to minimize total costs and transpor...

  19. A two-period model of Closed-loop Supply Chain

    NARCIS (Netherlands)

    De Giovanni, P.; Zaccour, G.

    2014-01-01

    We consider a two-period closed-loop supply chain (CLSC) game where a remanufacturer appropriates of the returns' residual value and decides whether to exclusively manage the end-of-use product collection or to outsource it to either a retailer or a third-service provider (3P). We determine that the

  20. Multi-loop correlators for rational theories of 2D gravity from the generalized Kontsevich models

    DEFF Research Database (Denmark)

    Kristjansen, C.

    1994-01-01

    functions of the susceptibilities and the eigenvalues of the external field. We furthermore use the moment technique to derive a closed expression for the genus zero multi-loop correlators for $(3,3m-1)$ and $(3,3m-2)$ rational matter fields coupled to gravity. We comment on the relation between the two-matrix...

  1. Mathematical model of a multi-loop network of gas pipelines at various modes of current

    Directory of Open Access Journals (Sweden)

    Orifjon Sh. Bozorov

    2012-05-01

    Full Text Available A method of hydraulic calculation of a multi-loop network of gas pipelines based on Kirchhoff’s laws is offered. As completing relations, the formula for the change of pressure on elementary sites of the horizontal gas pipe, received on the basis of Leybenzon’s generalized formula of resistance is used.

  2. Primary culture of intestinal epithelial cells as a potential model for Toxoplasma gondii enteric cycle studies

    Directory of Open Access Journals (Sweden)

    Marcos de Assis Moura

    2009-09-01

    Full Text Available The primary culture of intestinal epithelial cells from domestic cats is an efficient cellular model to study the enteric cycle of Toxoplasma gondii in a definitive host. The parasite-host cell ratio can be pointed out as a decisive factor that determines the intracellular fate of bradyzoites forms. The development of the syncytial-like forms of T. gondii was observed using the 1:20 bradyzoite-host cell ratio, resulting in similar forms described in in vivo systems. This alternative study potentially opens up the field for investigation into the molecular aspects of this interaction. This can contribute to the development of new strategies for intervention of a main route by which toxoplasmosis spreads.

  3. Antibiotic selection of Escherichia coli sequence type 131 in a mouse intestinal colonization model

    DEFF Research Database (Denmark)

    Hertz, Frederik Boetius; Løbner-Olesen, Anders; Frimodt-Møller, Niels

    2014-01-01

    day, antibiotic treatment was initiated and given subcutaneously once a day for three consecutive days. CFU of E. coli ST131, Bacteroides, and Gram-positive aerobic bacteria in fecal samples were studied, with intervals, until day 8. Bacteroides was used as an indicator organism for impact on the Gram......-negative anaerobic population. For three antibiotics, prolonged colonization was investigated with additional fecal CFU counts determined on days 10 and 14 (cefotaxime, dicloxacillin, and clindamycin). Three antibiotics (cefotaxime, dicloxacillin, and clindamycin) promoted overgrowth of E. coli ST131 (P ...The ability of different antibiotics to select for extended-spectrum β-lactamase (ESBL)-producing Escherichia coli remains a topic of discussion. In a mouse intestinal colonization model, we evaluated the selective abilities of nine common antimicrobials (cefotaxime, cefuroxime, dicloxacillin...

  4. Protective Effects of L-Carnitine on Intestinal Ischemia/Reperfusion Injury in a Rat Model

    OpenAIRE

    Yuan, Yong; Guo, Hao; Zhang, Yi; Zhou, Dong; Gan, Ping; Liang, Dao Ming; Chen, Jia Yong

    2011-01-01

    Background Ischemia/reperfusion (IR) injury of the intestine is a major problem in abdominal pathological condition and is associated with a high morbidity and mortality. The purpose of the study is to determine whether the L-carnitine can prevent the harmful effects of small intestinal IR injury in rats. Methods Thirty Sprague-Dawley rats were randomly divided into three groups. Sham operated group (S), for shamoperated, the IR group for rats submitted to 45-minute of intestinal ischemia and...

  5. Fuzzy logic application for modeling man-in-the-loop space shuttle proximity operations. M.S. Thesis - MIT

    Science.gov (United States)

    Brown, Robert B.

    1994-01-01

    A software pilot model for Space Shuttle proximity operations is developed, utilizing fuzzy logic. The model is designed to emulate a human pilot during the terminal phase of a Space Shuttle approach to the Space Station. The model uses the same sensory information available to a human pilot and is based upon existing piloting rules and techniques determined from analysis of human pilot performance. Such a model is needed to generate numerous rendezvous simulations to various Space Station assembly stages for analysis of current NASA procedures and plume impingement loads on the Space Station. The advantages of a fuzzy logic pilot model are demonstrated by comparing its performance with NASA's man-in-the-loop simulations and with a similar model based upon traditional Boolean logic. The fuzzy model is shown to respond well from a number of initial conditions, with results typical of an average human. In addition, the ability to model different individual piloting techniques and new piloting rules is demonstrated.

  6. System Dynamics Modelling of Remanufacturing and Recycling Mode Based on Closed-Loop Across-Chain Competition

    Directory of Open Access Journals (Sweden)

    Shidi Miao

    2017-01-01

    Full Text Available To face the reality of resources exhaustion, the significance of recycling and remanufacturing in the closed-loop chain has become quite evident. This paper constructs a competitive recycling and remanufacturing model of the closed-loop supply chain through a case study of Midea Corp. and Gree Corp. and explores the impact of two recycling modes on total revenue of the supply chain and market share. The simulation results show that the total revenue of the supply chain will benefit from the increasing coverage points by the third party and the increasing environmental awareness of certain regions. The retailers show more enthusiasm of recycling through certain amendment of the contract between manufacturers and retailers. The time of payment could be shortened in closed loop. Moreover, the improvement of recycling mechanism of the retailers can enlarge the share of supply chain market. Guiding role of the proposed model and the simulation results played in establishing a better supply chain mode is presented.

  7. Constraints on abelian extensions of the Standard Model from two-loop vacuum stability and U(1) B- L

    Science.gov (United States)

    Corianò, Claudio; Rose, Luigi Delle; Marzo, Carlo

    2016-02-01

    We present a renormalization group study of the scalar potential in a minimal U(1) B- L extension of the Standard Model involving one extra heavier Higgs and three heavy right-handed neutrinos with family universal B-L charge assignments. We implement a type-I seesaw for the masses of the light neutrinos of the Standard Model. In particular, compared to a previous study, we perform a two-loop extension of the evolution, showing that two-loop effects are essential for the study of the stability of the scalar potential up to the Planck scale. The analysis includes the contribution of the kinetic mixing between the two abelian gauge groups, which is radiatively generated by the evolution, and the one-loop matching conditions at the electroweak scale. By requiring the stability of the potential up to the Planck mass, significant constraints on the masses of the heavy neutrinos, on the gauge couplings and the mixing in the Higgs sector are identified.

  8. GoSam-2.0. A tool for automated one-loop calculations within the Standard Model and beyond

    International Nuclear Information System (INIS)

    Cullen, Gavin; Deurzen, Hans van; Greiner, Nicolas

    2014-05-01

    We present the version 2.0 of the program package GoSam for the automated calculation of one-loop amplitudes. GoSam is devised to compute one-loop QCD and/or electroweak corrections to multi-particle processes within and beyond the Standard Model. The new code contains improvements in the generation and in the reduction of the amplitudes, performs better in computing time and numerical accuracy, and has an extended range of applicability. The extended version of the ''Binoth-Les-Houches-Accord'' interface to Monte Carlo programs is also implemented. We give a detailed description of installation and usage of the code, and illustrate the new features in dedicated examples.

  9. Understanding looping kinetics of a long polymer molecule in solution. Exact solution for delta function sink model

    Science.gov (United States)

    Ganguly, Moumita; Chakraborty, Aniruddha

    2017-10-01

    A diffusion theory for intramolecular reactions of polymer chain in dilute solution is formulated. We give a detailed analytical expression for calculation of rate of polymer looping in solution. The physical problem of looping can be modeled mathematically with the use of a Smoluchowski-like equation with a Dirac delta function sink of finite strength. The solution of this equation is expressed in terms of Laplace Transform of the Green's function for end-to-end motion of the polymer in absence of the sink. We have defined two different rate constants, the long term rate constant and the average rate constant. The average rate constant and long term rate constant varies with several parameters such as length of the polymer (N), bond length (b) and the relaxation time τR. The long term rate constant is independent of the initial probability distribution.

  10. [Establishment and comparison of stoma and stoma-free heterotopic small intestine transplantation models in mice].

    Science.gov (United States)

    Meng, Ning; Pan, Zhijian; Liu, Yadong; Xu, Xin; Shen, Jiliang; Shen, Bo

    2016-03-01

    To establish stoma and stoma-free murine models of heterotopic small intestine transplantation in order to choose a more effective and reliable model. A total of 140 male 8-10 weeks age C57BL/6(B6) mice weighted 25-30 g were enrolled in the experiment. Syngeneic heterotopic small intestine transplantation was performed between C57BL/6 mice, and recipient mice were divided into either stoma or stoma-free group. Heterotopic small intestine transplantation was performed in 70 mice, with 35 mice in each group. After closing the proximal end of the graft by ligation, the distal end of graft was exteriorized as a stoma then secured to the skin of the abdominal wall in stoma group. In stoma-free group, the distal end of graft was anastomosed end-to-side to the recipient ileum. Successful rate of operation, two-week survival rate, operation time, associated complications, postoperative care time and body weight change were recorded and compared between two groups. The successful rate of stoma group was 65.7%, while it was 80.0% of stoma-free group (χ(2)=1.806, P=0.179). The operation time of donor in stoma group was (48.1±6.6) minutes, while it was (47.2±5.9) minutes in stoma-free group (t=0.598, P=0.552). The operation time of recipient in stoma group was (77.9±9.1) minutes, while it was (76.4±8.3) minutes in stoma-free group (t=0.683, P=0.497). The cold ischemic time of graft in stoma group was (34.7±4.0) minutes, while it was (33.9±4.6) minutes in stoma-free group(t=0.667, P=0.507). The two-week survival rate of stoma group was 45.7%, and it was 77.1% of stoma-free group(χ(2)=7.295, P=0.007). The stoma group had more complications[54.3%(19/35) vs. 22.9%(8/35), χ(2)=7.295, P=0.007], which needed more postoperative care time(191 min vs. 35 min). The weight loss in stoma group in the third day after operation was more significant [(81.52±5.20)% vs. (85.46±4.65)%, t=2.856, P=0.006]. By 2 weeks after operation, the weight of mice in both groups retruned to 95% of

  11. Loop Shaping Control Design for a Supersonic Propulsion System Model Using Quantitative Feedback Theory (QFT) Specifications and Bounds

    Science.gov (United States)

    Connolly, Joseph W.; Kopasakis, George

    2010-01-01

    This paper covers the propulsion system component modeling and controls development of an integrated mixed compression inlet and turbojet engine that will be used for an overall vehicle Aero-Propulso-Servo-Elastic (APSE) model. Using previously created nonlinear component-level propulsion system models, a linear integrated propulsion system model and loop shaping control design have been developed. The design includes both inlet normal shock position control and jet engine rotor speed control for a potential supersonic commercial transport. A preliminary investigation of the impacts of the aero-elastic effects on the incoming flow field to the propulsion system are discussed, however, the focus here is on developing a methodology for the propulsion controls design that prevents unstart in the inlet and minimizes the thrust oscillation experienced by the vehicle. Quantitative Feedback Theory (QFT) specifications and bounds, and aspects of classical loop shaping are used in the control design process. Model uncertainty is incorporated in the design to address possible error in the system identification mapping of the nonlinear component models into the integrated linear model.

  12. Anti-inflammatory intestinal activity ofCombretum duarteanumCambess. in trinitrobenzene sulfonic acid colitis model.

    Science.gov (United States)

    de Morais Lima, Gedson Rodrigues; Machado, Flavia Danniele Frota; Périco, Larissa Lucena; de Faria, Felipe Meira; Luiz-Ferreira, Anderson; Souza Brito, Alba Regina Monteiro; Pellizzon, Cláudia Helena; Hiruma-Lima, Clélia Akiko; Tavares, Josean Fechine; Barbosa Filho, José Maria; Batista, Leônia Maria

    2017-02-28

    To evaluate the anti-inflammatory intestinal effect of the ethanolic extract (EtOHE) and hexane phase (HexP) obtained from the leaves of Combretum duarteanum ( Cd ). Inflammatory bowel disease was induced using trinitrobenzenesulfonic acid in acute and relapsed ulcerative colitis in rat models. Damage scores, and biochemical, histological and immunohistochemical parameters were evaluated. Both Cd -EtOHE and Cd -HexP caused significant reductions in macroscopic lesion scores and ulcerative lesion areas. The vegetable samples inhibited myeloperoxidase increase, as well as pro-inflammatory cytokines TNF-α and IL-1β. Anti-inflammatory cytokine IL-10 also increased in animals treated with the tested plant samples. The anti-inflammatory intestinal effect is related to decreased expression of cyclooxygenase-2, proliferating cell nuclear antigen, and an increase in superoxide dismutase. The data indicate anti-inflammatory intestinal activity. The effects may also involve participation of the antioxidant system and principal cytokines relating to inflammatory bowel disease.

  13. LoopIng: a template-based tool for predicting the structure of protein loops.

    KAUST Repository

    Messih, Mario Abdel

    2015-08-06

    Predicting the structure of protein loops is very challenging, mainly because they are not necessarily subject to strong evolutionary pressure. This implies that, unlike the rest of the protein, standard homology modeling techniques are not very effective in modeling their structure. However, loops are often involved in protein function, hence inferring their structure is important for predicting protein structure as well as function.We describe a method, LoopIng, based on the Random Forest automated learning technique, which, given a target loop, selects a structural template for it from a database of loop candidates. Compared to the most recently available methods, LoopIng is able to achieve similar accuracy for short loops (4-10 residues) and significant enhancements for long loops (11-20 residues). The quality of the predictions is robust to errors that unavoidably affect the stem regions when these are modeled. The method returns a confidence score for the predicted template loops and has the advantage of being very fast (on average: 1 min/loop).www.biocomputing.it/loopinganna.tramontano@uniroma1.itSupplementary data are available at Bioinformatics online.

  14. Property profiling of biosimilar mucus in a novel mucus-containing in vitro model for assessment of intestinal drug absorption

    DEFF Research Database (Denmark)

    Bøgh, Marie; Baldursdóttir, Stefania G; Müllertz, Anette

    2014-01-01

    to establish a more representative in vitro model for the intestinal mucosa. The rheological profile of a biosimilar mucus mixture composed of purified gastric mucin, lipids and protein in buffer was optimized by supplementing with an anionic polymer to display viscoelastic properties and a microstructure...

  15. Effect of erythropoietin on intestinal injury and bacterial translocation in neonatal rat model of necrotizing enterocolitis

    Directory of Open Access Journals (Sweden)

    Xiao-qing CHEN

    2012-05-01

    Full Text Available Objective  To observe the influence of erythropoietin (EPO on intestinal histopathological changes and bacterial translocation (BT in neonatal rat model of necrotizing enterocolitis (NEC, and explore the protective effect of EPO against NEC. Methods  Seventy-five three-day-old SD rat pups were randomly divided into three groups (25 in each group: normal control group, NEC model group and EPO intervention group. The rat pups in normal control group were placed together with their mothers and breast fed, receiving no other intervention. NEC model group rats were separated from their mothers, housed in an incubator, and gavaged with rat-milk substitute, then experienced hypoxia (breathing 100% nitrogen gas for 90s and cold stress (4℃ for 10min three times daily for 3 days. EPO intervention group rats were fed with the substitute of rat-milk supplemented with 0.1U/ml of EPO, and they were also given hypoxia and cold stress similar to that of the NEC model group. Blood samples were obtained via cardiac puncture, and 2-cm-length of terminal ileum proximal to the ileocecal valve were obtained from the animals on the 4th day. The histopathological changes in terminal ileum were scored after hematoxylin-eosin (HE staining, and the scores ≥2 were defined as NEC. To determine the incidence of bacterial translocation, 16S rRNA real-time fluorescence quantitative PCR was used to detect the bacterial DNA in blood samples. Results  Compared with the NEC model group, the mean rank-sum rate of the intestinal histopathological score (39.4583 vs 53.8696, NEC incidence [25%(6/24 vs 57%(13/23] and bacterial translocation rate [17% (4/24 vs 65%(15/23] in EPO intervention group were significantly lowered (P < 0.05, P < 0.01. Conclusion  Enteral EPO administration is not only effective for reduction of the severity and incidence of NEC, but also for decrease of the bacterial translocation rate in neonatal rat models.

  16. Octreotide in Intestinal Lymphangiectasia: Lack of a Clinical Response and Failure to Alter Lymphatic Function in a Guinea Pig Model

    Directory of Open Access Journals (Sweden)

    S Makhija

    2004-01-01

    Full Text Available Intestinal lymphangiectasia, which can be classified as primary or secondary, is an unusual cause of protein-losing enteropathy. The main clinical features include edema, fat malabsorption, lymphopenia and hypoalbuminemia. Clinical management generally includes a low-fat diet and supplementation with medium chain triglycerides. A small number of recent reports advocate the use of octreotide in intestinal lymphangiectasia. It is unclear why octreotide was used in these studies; although octreotide can alter splanchnic blood flow and intestinal motility, its actions on lymphatic function has never been investigated. A case of a patient with intestinal lymphangiectasia who required a shunt procedure after failing medium chain triglycerides and octreotide therapy is presented. During the management of this case, all existing literature on intestinal lymphangiectasia and all the known actions of octreotide were reviewed. Because some of the case reports suggested that octreotide may improve the clinical course of intestinal lymphangiectasia by altering lymphatic function, a series of experiments were undertaken to assess this. In an established guinea pig model, the role of octreotide in lymphatic function was examined. In this model system, the mesenteric lymphatic vessels responded to 5-hydroxytryptamine with a decrease in constriction frequency, while histamine administration markedly increased lymphatic constriction frequency. Octreotide failed to produce any change in lymphatic function when a wide range of concentrations were applied to the mesenteric lymphatic vessel preparation. In conclusion, in this case, octreotide failed to induce a clinical response and laboratory studies showed that octreotide did not alter lymphatic function. Thus, the mechanisms by which octreotide induced clinical responses in the cases reported elsewhere in the literature remain unclear, but the present study suggests that it does not appear to act via increasing

  17. One loop corrections to the lightest Higgs mass in the minimal η model with a heavy Z'

    International Nuclear Information System (INIS)

    Comelli, D.

    1992-06-01

    We have evaluated the one loop correction to the bound on the lightest Higgs mass valid in the minimal, E 6 based, supersymmetric η model in the presence of a 'heavy' Z', M z' ≥1 TeV. The dominant contribution from the fermion sfermion sector increases the 108 GeV tree level value by an amount that depends on the top mass in a way that is largely reminescent of minimal SUSY models. For M t ≤150 GeV, Msub(t tilde)=1 TeV, the 'light' Higgs mass is always ≤130 GeV. (orig.)

  18. Investigation of Microbiota Alterations and Intestinal Inflammation Post-Spinal Cord Injury in Rat Model.

    Science.gov (United States)

    O'Connor, Gregory; Jeffrey, Elisabeth; Madorma, Derik; Marcillo, Alexander; Abreu, Maria T; Deo, Sapna K; Dietrich, W Dalton; Daunert, Sylvia

    2018-03-23

    Although there has been a significant amount of research focused on the pathophysiology of Spinal Cord Injury (SCI), there is limited information on the consequences of SCI on remote organs. SCI can produce significant effects on a variety of organ systems, including the gastrointestinal tract. Patients with SCI often suffer from severe, debilitating bowel dysfunction in addition to their physical disabilities, which is of major concern for these individuals due to the adverse impact on their quality of life. Herein, we report on our investigation into the effects of SCI and subsequent antibiotic treatment on the intestinal tissue and microbiota. For that, we employed a thoracic SCI rat model and investigated changes to the microbiota, pro-inflammatory cytokine levels, and bacterial communication molecule levels post injury and gentamicin treatment for seven days. We discovered significant changes, the most interesting being the differences in the gut microbiota beta diversity of 8-week SCI animals compared to control animals at the family, genus, and species level. Specifically, 35 Operational Taxonomic Units (OTUs) were enriched in the SCI animal group and 3 were identified at species level; Lactobacillus intestinalis, Clostridium disporicum, and Bifidobacterium choerinum. In contrast, Clostridium saccharogumia was identified as depleted in the SCI animal group. Pro-inflammatory cytokines IL-12, MIP-2, and TNF-α, were found to be significantly elevated in intestinal tissue homogenate 4-weeks post-SCI compared to 8-weeks post-injury. Further, levels of IL-1β, IL-12, and MIP-2 significantly correlated with changes in beta diversity 8-weeks post-SCI. Our data provide a greater understanding of the early effects of SCI on the microbiota and gastrointestinal tract, highlighting the need for further investigation to elucidate the mechanism underlying these effects.

  19. Live Faecalibacterium prausnitzii in an apical anaerobic model of the intestinal epithelial barrier

    NARCIS (Netherlands)

    Ulluwishewa, D.; Anderson, R.C.; Young, W.; McNabb, W.C.; Baarlen, van P.; Moughan, P.J.; Wells, J.M.; Roy, N.C.

    2015-01-01

    Faecalibacterium prausnitzii, an abundant member of the human commensal microbiota, has been proposed to have a protective role in the intestine. However, it is an obligate anaerobe, difficult to co-culture in viable form with oxygen-requiring intestinal cells. To overcome this limitation, a unique

  20. Preservation of intestinal microvascular Po2 during normovolemic hemodilution in a rat model

    NARCIS (Netherlands)

    van Bommel, J.; Siegemund, M.; Henny, C. P.; van den Heuvel, D. A.; Trouwborst, A.; Ince, C.

    2000-01-01

    The effect of hemodilution on the intestinal microcirculatory oxygenation is not clear. The aim of this study was to determine the effect of moderate normovolemic hemodilution on intestinal microvascular partial oxygen pressure (Po2) and its relation to the mesenteric venous Po2 (Pmvo2).

  1. Small intestine diverticuli

    International Nuclear Information System (INIS)

    Pomakov, P.; Risov, A.

    1991-01-01

    The routine method of contrast matter passage applied to 850 patients with different gastrointestinal diseases proved inefficient to detect any small-intestinal diverticuli. The following modiffications of the method have been tested in order to improve the diagnostic possibilities of the X-ray: study at short intervals, assisted passage, enteroclysm, pharmacodynamic impact, retrograde filling of the ileum by irrigoscopy. Twelve diverticuli of the small-intestinal loops were identified: 5 Meckel's diverticuli, 2 solitary of which one of the therminal ileum, 2 double diverticuli and 1 multiple diverticulosis of the jejunum. The results show that the short interval X-ray examination of the small intestines is the method of choice for identifying local changes in them. The solitary diverticuli are not casuistic scarcity, its occurrence is about 0.5% at purposeful X-ray investigation. The assisted passage method is proposed as a method of choice for detection of the Meckel's diverticulum. 5 figs., 3 tabs. 18 refs

  2. A 3D intestinal tissue model supports Clostridioides difficile germination, colonization, toxin production and epithelial damage.

    Science.gov (United States)

    Shaban, Lamyaa; Chen, Ying; Fasciano, Alyssa C; Lin, Yinan; Kaplan, David L; Kumamoto, Carol A; Mecsas, Joan

    2018-04-01

    Endospore-forming Clostridioides difficile is a causative agent of antibiotic-induced diarrhea, a major nosocomial infection. Studies of its interactions with mammalian tissues have been hampered by the fact that C. difficile requires anaerobic conditions to survive after spore germination. We recently developed a bioengineered 3D human intestinal tissue model and found that low O 2 conditions are produced in the lumen of these tissues. Here, we compared the ability of C. difficile spores to germinate, produce toxin and cause tissue damage in our bioengineered 3D tissue model versus in a 2D transwell model in which human cells form a polarized monolayer. 3D tissue models or 2D polarized monolayers on transwell filters were challenged with the non-toxin producing C. difficile CCUG 37787 serotype X (ATCC 43603) and the toxin producing UK1 C. difficile spores in the presence of the germinant, taurocholate. Spores germinated in both the 3D tissue model as well as the 2D transwell system, however toxin activity was significantly higher in the 3D tissue models compared to the 2D transwells. Moreover, the epithelium damage in the 3D tissue model was significantly more severe than in 2D transwells and damage correlated significantly with the level of toxin activity detected but not with the amount of germinated spores. Combined, these results show that the bioengineered 3D tissue model provides a powerful system with which to study early events leading to toxin production and tissue damage of C. difficile with mammalian cells under anaerobic conditions. Furthermore, these systems may be useful for examining the effects of microbiota, novel drugs and other potential therapeutics directed towards C. difficile infections. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Neutron transport in irradiation loops (IRENE loop)

    International Nuclear Information System (INIS)

    Sarsam, Maher.

    1980-09-01

    This thesis is composed of two parts with different aspects. Part one is a technical description of the loop and its main ancillary facilities as well as of the safety and operational regulations. The measurement methods on the model of the ISIS reactor and on the loop in the OSIRIS reactor are described. Part two deals with the possibility of calculating the powers dissipated by each rod of the fuel cluster, using appropriate computer codes, not only in the reflector but also in the core and to suggest a method of calculation [fr

  4. An increased CD25-positive intestinal regulatory T lymphocyte population is dependent upon Cox-2 activity in the Apcmin/+ model.

    Science.gov (United States)

    Faluyi, O O; Fitch, P; Howie, S E M

    2018-01-01

    Only mismatch repair (MMR)-deficient colorectal cancer (CRC) appears to respond well to programmed death (PD)-1 inhibition at the present time. Emerging evidence suggests a role for micro-environmental factors such as CD25 + cells modulating response to PD-1 inhibition. In the Apc Min/+ model of familial adenomatous polyposis (MMR-proficient CRC), increased Cyclooxygenase-2 (Cox-2) expression by cells which include alternatively activated mononuclear phagocytes promotes intestinal tumorigenesis by mechanisms which may include immune suppression. To gain insight into this, we compared regulatory T cell (T reg ) populations between Apc Min/+ and wild-type mice prior to and after the phase of increased intestinal Cox-2-dependent prostaglandin E 2 (PGE 2 ) production. There was no difference in systemic T reg function or numbers between Apc Min/+ and wild-type mice. However, increased numbers of small intestinal CD25 + T regs were observed with increased Cox-2 activity in the absence of any difference in the expression of Tgf-β or Tslp between Apc Min/+ and wild-type mice. Cox-2 inhibitor therapy (Celecoxib) reversed the increase in Apc Min/+ intestinal CD25 + T reg numbers, without decreasing numbers of CD25 + systemic T regs . Forkhead box protein 3 (FoxP3 + ) and Cox-2 + cells were co-localized to the interstitium of adenomas of Apc min/+ mice. These results suggest selective dependence of an 'activated T reg ' phenotype on paracrine Cox-2 activity in Apc Min/+ small intestine. For therapeutic potential, further studies are required to evaluate the relevance of these findings to human cancer as well as the functional significance of CD25 + intestinal T regs in cancer. © 2017 British Society for Immunology.

  5. A fish intestinal epithelial barrier model established from the rainbow trout (Oncorhynchus mykiss) cell line, RTgutGC.

    Science.gov (United States)

    Minghetti, Matteo; Drieschner, Carolin; Bramaz, Nadine; Schug, Hannah; Schirmer, Kristin

    2017-12-01

    The intestine of fish is a multifunctional organ: lined by only a single layer of specialized epithelial cells, it has various physiological roles including nutrient absorption and ion regulation. It moreover comprises an important barrier for environmental toxicants, including metals. Thus far, knowledge of the fish intestine is limited largely to in vivo or ex vivo investigations. Recently, however, the first fish intestinal cell line, RTgutGC, was established, originating from a rainbow trout (Oncorhynchus mykiss). In order to exploit the opportunities arising from RTgutGC cells for exploring fish intestinal physiology and toxicology, we present here the establishment of cells on commercially available permeable membrane supports and evaluate its suitability as a model of polarized intestinal epithelia. Within 3 weeks of culture, RTgutGC cells show epithelial features by forming tight junctions and desmosomes between adjacent cells. Cells develop a transepithelial electrical resistance comparable to in vivo measured values, reflecting the leaky nature of the fish intestine. Immunocytochemistry reveals evidence of polarization, such as basolateral localization of Na + /K + -ATPase (NKA) and apical localization of the tight junction protein ZO-1. NKA mRNA abundance was induced as physiological response toward a saltwater buffer, mimicking the migration of rainbow trout from fresh to seawater. Permeation of fluorescent molecules proved the barrier function of the cells, with permeation coefficients being comparable to those reported in fish. Finally, we demonstrate that cells on permeable supports are more resistant to the toxicity elicited by silver ions than cells grown the conventional way, likely due to improved cellular silver excretion.

  6. The optimal intestinal segment length for experimental size-mismatched intestinal transplantation: Defining the maximum length with the lowest blood flow needs in a porcine model.

    Science.gov (United States)

    Frongia, Giovanni; Majlesara, Ali; Saffari, Arash; Emami, Golnaz; Golriz, Mohammad; Günther, Patrick; Mehrabi, Arianeb

    2018-03-01

    Transplanted Intestinal Segments (IS) must match the perfusion capacities of the recipient. This can be challenging during a size-mismatched SBTX. In this study, we defined the maximum IS length with lowest blood flow needs in a porcine model by evaluating the physiological perfusion rates of different IS lengths. Blood flow in the SMA, aorta segment four, and general circulatory parameters were monitored before and after sequential intestinal resection. IS lengths of 30 cm, 60 cm, 120 cm, and 300 cm (n = 8 each) were compared. The IS blood flow requirements increased with IS length (30 cm: 19.5 ± 3.4 mL/min; 60 cm: 16.9 ± 6.7 mL/min; 120 cm: 34.9 ± 8.5 mL/min; 300 cm: 62.9 ± 11.6 mL/min). Absolute IS blood flow (P = .004), percentage IS blood flow uptake from the SMA (P = .001), and percentage IS blood flow uptake from the aorta (P = .005) increased significantly between 60 cm and 120 cm. We concluded that 60 cm was the maximum IS length before blood flow demands significantly increased in a porcine model. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  7. Open-loop frequency response analysis of a wind turbine using a high-order linear aeroelastic model

    DEFF Research Database (Denmark)

    Sønderby, Ivan Bergquist; Hansen, Morten Hartvig

    2014-01-01

    generator torque and collective pitch control actions of a modern non-floating wind turbine based on a high-order linear model. The model is a linearization of a geometrically non-linear finite beam element model coupled with an unsteady blade element momentum model of aerodynamic forces including effects......Wind turbine controllers are commonly designed on the basis of low-order linear models to capture the aeroelastic wind turbine response due to control actions and disturbances. This paper characterizes the aeroelastic wind turbine dynamics that influence the open-loop frequency response from......-minimum phase zeros below the frequency of the first drivetrain mode. To correctly predict the non-minimum phase zeros, it is essential to include lateral tower and blade flap degrees of freedom. Copyright © 2013 John Wiley & Sons, Ltd....

  8. PVA gel as a potential adhesion barrier: a safety study in a large animal model of intestinal surgery.

    Science.gov (United States)

    Renz, Bernhard W; Leitner, Kurt; Odermatt, Erich; Worthley, Daniel L; Angele, Martin K; Jauch, Karl-Walter; Lang, Reinhold A

    2014-03-01

    Intra-abdominal adhesions following surgery are a major source of morbidity and mortality including abdominal pain and small bowel obstruction. This study evaluated the safety of PVA gel (polyvinyl alcohol and carboxymethylated cellulose gel) on intestinal anastomoses and its potential effectiveness in preventing adhesions in a clinically relevant large animal model. Experiments were performed in a pig model with median laparotomy and intestinal anastomosis following small bowel resection. The primary endpoint was the safety of PVA on small intestinal anastomoses. We also measured the incidence of postoperative adhesions in PVA vs. control groups: group A (eight pigs): stapled anastomosis with PVA gel compared to group B (eight pigs), which had no PVA gel; group C (eight pigs): hand-sewn anastomosis with PVA gel compared to group B (eight pigs), which had no anti-adhesive barrier. Animals were sacrificed 14 days after surgery and analyzed. All anastomoses had a patent lumen without any stenosis. No anastomoses leaked at an intraluminal pressure of 40 cmH2O. Thus, anastomoses healed very well in both groups, regardless of whether PVA was administered. PVA-treated animals, however, had significantly fewer adhesions in the area of stapled anastomoses. The hand-sewn PVA group also had weaker adhesions and trended towards fewer adhesions to adjacent organs. These results suggest that PVA gel does not jeopardize the integrity of intestinal anastomoses. However, larger trials are needed to investigate the potential of PVA gel to prevent adhesions in gastrointestinal surgery.

  9. Evaluation of an FDA approved library against laboratory models of human intestinal nematode infections.

    Science.gov (United States)

    Keiser, Jennifer; Panic, Gordana; Adelfio, Roberto; Cowan, Noemi; Vargas, Mireille; Scandale, Ivan

    2016-07-01

    Treatment options for infections with soil-transmitted helminths (STH) - Ascaris lumbricoides, Trichuris trichiura and the two hookworm species, Ancylostoma duodenale and Necator americanus - are limited despite their considerable global health burden. The aim of the present study was to test the activity of an openly available FDA library against laboratory models of human intestinal nematode infections. All 1,600 drugs were first screened against Ancylostoma ceylanicum third-stage larvae (L3). Active compounds were scrutinized and toxic compounds, drugs indicated solely for topical use, and already well-studied anthelmintics were excluded. The remaining hit compounds were tested in parallel against Trichuris muris first-stage larvae (L1), Heligmosomoides polygyrus third-stage larvae (L3), and adult stages of the three species in vitro. In vivo studies were performed in the H. polygyrus and T. muris mice models. Fifty-four of the 1,600 compounds tested revealed an activity of > 60 % against A. ceylanicum L3 (hit rate of 3.4 %), following incubation at 200 μM for 72 h. Twelve compounds progressed into further screens. Adult A. ceylanicum were the least affected (1/12 compounds active at 50 μM), while eight of the 12 test compounds revealed activity against T. muris L1 (100 μM) and adults (50 μM), and H. polygyrus L3 (200 μM). Trichlorfon was the only compound active against all stages of A. ceylanicum, H. polygyrus and T. muris. In addition, trichlorfon achieved high worm burden reductions of 80.1 and 98.9 %, following a single oral dose of 200 mg/kg in the T. muris and H. polygyrus mouse model, respectively. Drug screening on the larval stages of intestinal parasitic nematodes is feasible using small libraries and important given the empty drug discovery and development pipeline for STH infections. Differences and commonalities in drug activities across the different STH species and stages were confirmed. Hits identified might serve as a

  10. Heat transfer modelling in the vertical tubes of a natural circulation passive containment loop with noncondensable gas

    International Nuclear Information System (INIS)

    Herranz, L.E.; Munoz-Cobo, J.L.; Tachenko, I.; Sancho, J.; Escriva, A.; Verdu, G.

    1994-01-01

    One of the key safety systems of the Simplified Boiling Water Reactor (SBWR) of General Electric is the Passive Containment Cooling System (PCCS). This system is designed to behave as a heat sink without need of operator actions in case of a reactor accident. Such a function relies on setting up a natural circulation loop between drywell and wetwell. Along this loop heat is removed by condensing the steam coming from the drywell onto the inner surface of externally cooled vertical tubes. Therefore, a successful design of the condenser requires a good knowledge of the local heat transmission coefficients. In this paper a model of steam condensation into vertical tubes is presented. Based on a modified diffusion boundary layer approach for noncondensables, this model accounts for the effect of shear stress caused by the cocurrent steam-gas mixture on the liquid film thickness. An approximate method to calculate film thickness, avoiding iterative algorithms, has been proposed. At present, this model has been implemented in HTCPIPE code and its results are being checked in terms of local heat transfer coefficients against the experimental data available. A good agreement between measurements and predictions is being observed for tests at atmospheric pressure. Further development and validation of the model is needed to consider aspects such as mist formation, wavy flow and high pressure. (author)

  11. Identification of glucose-fermenting bacteria present in an in vitro model of the human intestine by RNA-stable isotope probing

    NARCIS (Netherlands)

    Egert, M.; Graaf, A.A. de; Maathuis, A.; Waard, P. de; Plugge, C.M.; Smidt, H.; Deutz, N.E.P.; Dijkema, C.; Vos, W.M. de; Venema, K.

    2007-01-01

    16S rRNA-based stable isotope probing (SIP) and nuclear magnetic resonance (NMR) spectroscopy-based metabolic profiling were used to identify bacteria fermenting glucose under conditions simulating the human intestine. The TIM-2 in vitro model of the human intestine was inoculated with a GI tract

  12. The effect of wellsolve, a novel solubilizing agent, on the intestinal barrier function and intestinal absorption of griseofulvin in rats.

    Science.gov (United States)

    Hamid, Khuriah Abdul; Lin, Yulian; Gao, Yang; Katsumi, Hidemasa; Sakane, Toshiyasu; Yamamoto, Akira

    2009-11-01

    The effect of Wellsolve, a new solubilizing agent, on the function of intestinal membrane barrier and transporters including P-glycoprotein (P-gp) and peptide transporter (PEPT1) was examined by an in vitro diffusion chamber and an in situ closed loop method. The model drugs used in this study were 5(6)-carboxyfluorescein (CF), rhodamine123 (a P-glycoprotein substrate), cephalexin (a typical substrate for PEPT1) and griseofulvin (a BCS Class II drug). Intestinal absorption of CF was not affected by the addition of 1-10% (v/v) Wellsolve, while 20% (v/v) Wellsolve significantly enhanced its intestinal absorption by the in situ absorption study. Therefore, this finding suggested that high concentration of Wellsolve might alter the intestinal barrier function. The mucosal to serosal (absorptive) and serosal to mucosal (secretory) transport of rhodamine123 was significantly inhibited in the presence of 5.0-20% (v/v) of Wellsolve, suggesting that Wellsolve might not affect the function of P-gp in the intestine. The intestinal transport of cephalexin was not affected in the presence of Wellsolve, suggesting that this solubilizing agent might not change the function of PEPT1 in the intestine. In the toxicity studies, we found that 1-10% (v/v) Wellsolve did not change the release of lactate hydrogenase (LDH) and protein from the intestinal membranes. Furthermore, intestinal absorption of griseofulvin in the presence of 10% (v/v) Wellsolve significantly increased as compared with the control. In summary, Wellsolve at lower concentrations might be a potent and safe solubilizing agent for improving the solubility and absorption of poorly water-soluble drugs including griseofulvin.

  13. Synthesis of protein in intestinal cells exposed to cholera toxin

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, J.W.; Berg, W.D. Jr.; Coppenhaver, D.H.

    1987-11-01

    The mechanism by which cyclic adenosine monophosphate (AMP), formed by intestinal epithelial cells in response to cholera toxin, ultimately results in alterations in water and electrolyte transport is poorly understood. Several studies have indicated that inhibitors of transcription or translation block much of the transport of ions and water in the intestine and edema formation in tissue elicited by cholera toxin. Data presented in this study confirmed the inhibitory effects of cycloheximide on cholera toxin-induced fluid accumulation in the rabbit intestinal loop model. Neither cycloheximide nor actinomycin D altered the amount of cyclic AMP that accumulated in intestinal cells and Chinese hamster ovary cells exposed to cholera toxin. An increase in (/sup 3/H) leucine incorporation was readily demonstrable in intestinal epithelial cells from rabbits challenged with Vibrio cholerae. Similarly, intestinal epithelial cells incubated with cholera toxin for 4 hr synthesized substantially more protein than controls as determined by relative incorporation of (/sup 35/S) methionine. Most of the new protein synthesized in response to cholera toxin was membrane associated and of high molecular weight. The possible significance of the toxin-induced protein relative to cholera pathogenesis was discussed.

  14. Synthesis of protein in intestinal cells exposed to cholera toxin

    International Nuclear Information System (INIS)

    Peterson, J.W.; Berg, W.D. Jr.; Coppenhaver, D.H.

    1987-01-01

    The mechanism by which cyclic adenosine monophosphate (AMP), formed by intestinal epithelial cells in response to cholera toxin, ultimately results in alterations in water and electrolyte transport is poorly understood. Several studies have indicated that inhibitors of transcription or translation block much of the transport of ions and water in the intestine and edema formation in tissue elicited by cholera toxin. Data presented in this study confirmed the inhibitory effects of cycloheximide on cholera toxin-induced fluid accumulation in the rabbit intestinal loop model. Neither cycloheximide nor actinomycin D altered the amount of cyclic AMP that accumulated in intestinal cells and Chinese hamster ovary cells exposed to cholera toxin. An increase in [ 3 H] leucine incorporation was readily demonstrable in intestinal epithelial cells from rabbits challenged with Vibrio cholerae. Similarly, intestinal epithelial cells incubated with cholera toxin for 4 hr synthesized substantially more protein than controls as determined by relative incorporation of [ 35 S] methionine. Most of the new protein synthesized in response to cholera toxin was membrane associated and of high molecular weight. The possible significance of the toxin-induced protein relative to cholera pathogenesis was discussed

  15. Two-loop coupling constant renormalization in lattice SU(N)xSU(N) 2D chiral models

    Energy Technology Data Exchange (ETDEWEB)

    Magnoli, N.; Ravanini, F.

    1986-08-01

    For the most general link action of lattice SU(N)xSU(N) two dimensional chiral models, the two loop coupling constant renormalization is discussed in the context of the background field method. A non-linear reparametrization of the fields, necessary to keep the invariance of the theory, introduces unpleasant extra-terms. However some of the non-universal contributions are unaffected by these extra-terms and can be easily calculated. This allows to compute the difference between the first non-universal coefficients of the Callan-Symanzik beta functions for two actions having the same scale ..lambda...

  16. Loop quantization of the polarized Gowdy model on T{sup 3}: kinematical states and constraint operators

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Kinjal; Date, Ghanashyam [Institute of Mathematical Sciences, CIT Campus, Chennai-600 113 (India)], E-mail: kinjal@imsc.res.in, E-mail: shyam@imsc.res.in

    2008-07-21

    In this second paper on loop quantization of the Gowdy model, we introduce the kinematical Hilbert space on which appropriate holonomies and fluxes are well represented. The quantization of the volume operator and the Gauss constraint is straightforward. Imposition of the Gauss constraint can be done on the kinematical Hilbert space to select subspace of gauge-invariant states. We carry out the quantization of the Hamiltonian constraint making specific choices. Alternative choices are briefly discussed. It appears that to get spatial correlations reflected in the Hamiltonian constraint, one may have to adopt the so-called effective operator viewpoint.

  17. The role of intestinal endotoxemia in a rat model of aluminum neurotoxicity.

    Science.gov (United States)

    Wang, Feng; Guo, Rui-Xia; Li, Wen-Xing; Yu, Bao-Feng; Han, Bai; Liu, Li-Xin; Han, De-Wu

    2017-08-01

    The present study aimed to investigate the effects of intestinal endotoxemia (IETM) in a rat model of aluminum neurotoxicity established by D-galactose and aluminum trichloride (AlCl3). Adult Wistar rats were administered D‑galactose and AlCl3 to create the aluminum neurotoxicity model. The learning and memory abilities of the rats were subsequently observed using a Morris water maze test and the serum levels of lipopolysaccharide (LPS), tumor necrosis factor (TNF)‑α, interleukin (IL)‑1, diamine oxidase (DAO), glutamine (Gln) and glutaminase were measured. The expression of S‑100β in the serum was detected using an enzyme‑linked immunosorbent assay. The expression levels of the amyloid β‑protein (Aβ) precursor (APP), presenilin 1 (PS1), β‑site APP‑cleaving enzyme (BACE), zona occludens protein (ZO)‑1 and Aβ 1‑40 in the brain of rats were detected via reverse‑transcription polymerase chain reaction, western blotting and immunohistochemistry. The levels of LPS, TNF‑α, IL‑1, DAO, Gln and S‑100β in serum and the mRNA and protein expression levels of APP, PS1, BACE and Aβ1‑40 in the brain were markedly increased in the model rats compared with controls. The level of glutaminase in the serum and the expression of ZO‑1 in the brain were decreased in the model rats compared with controls. IETM was present in the rat model of aluminum neurotoxicity established by D‑galactose and AlCl3 and may be important in the development of this neurotoxicity.

  18. Collective estimation of multiple bivariate density functions with application to angular-sampling-based protein loop modeling

    KAUST Repository

    Maadooliat, Mehdi

    2015-10-21

    This paper develops a method for simultaneous estimation of density functions for a collection of populations of protein backbone angle pairs using a data-driven, shared basis that is constructed by bivariate spline functions defined on a triangulation of the bivariate domain. The circular nature of angular data is taken into account by imposing appropriate smoothness constraints across boundaries of the triangles. Maximum penalized likelihood is used to fit the model and an alternating blockwise Newton-type algorithm is developed for computation. A simulation study shows that the collective estimation approach is statistically more efficient than estimating the densities individually. The proposed method was used to estimate neighbor-dependent distributions of protein backbone dihedral angles (i.e., Ramachandran distributions). The estimated distributions were applied to protein loop modeling, one of the most challenging open problems in protein structure prediction, by feeding them into an angular-sampling-based loop structure prediction framework. Our estimated distributions compared favorably to the Ramachandran distributions estimated by fitting a hierarchical Dirichlet process model; and in particular, our distributions showed significant improvements on the hard cases where existing methods do not work well.

  19. A Closed-Loop Model of Operator Visual Attention, Situation Awareness, and Performance Across Automation Mode Transitions.

    Science.gov (United States)

    Johnson, Aaron W; Duda, Kevin R; Sheridan, Thomas B; Oman, Charles M

    2017-03-01

    This article describes a closed-loop, integrated human-vehicle model designed to help understand the underlying cognitive processes that influenced changes in subject visual attention, mental workload, and situation awareness across control mode transitions in a simulated human-in-the-loop lunar landing experiment. Control mode transitions from autopilot to manual flight may cause total attentional demands to exceed operator capacity. Attentional resources must be reallocated and reprioritized, which can increase the average uncertainty in the operator's estimates of low-priority system states. We define this increase in uncertainty as a reduction in situation awareness. We present a model built upon the optimal control model for state estimation, the crossover model for manual control, and the SEEV (salience, effort, expectancy, value) model for visual attention. We modify the SEEV attention executive to direct visual attention based, in part, on the uncertainty in the operator's estimates of system states. The model was validated using the simulated lunar landing experimental data, demonstrating an average difference in the percentage of attention ≤3.6% for all simulator instruments. The model's predictions of mental workload and situation awareness, measured by task performance and system state uncertainty, also mimicked the experimental data. Our model supports the hypothesis that visual attention is influenced by the uncertainty in system state estimates. Conceptualizing situation awareness around the metric of system state uncertainty is a valuable way for system designers to understand and predict how reallocations in the operator's visual attention during control mode transitions can produce reallocations in situation awareness of certain states.

  20. Intestinal Obstruction

    Science.gov (United States)

    ... the obstruction along the intestines. Treatment Suction via nasogastric tube Fluids given by vein Surgery for strangulation Sometimes ... nose and placed in the stomach (called a nasogastric tube) or into the intestine. Suction is applied to ...

  1. Enterohemorrhagic Escherichia coli induce attaching and effacing lesions and hemorrhagic colitis in human and bovine intestinal xenograft models

    Directory of Open Access Journals (Sweden)

    Lilach Golan

    2011-01-01

    Enterohemorrhagic Escherichia coli (EHEC O157:H7 is an important cause of diarrhea, hemorrhagic colitis and hemolytic uremic syndrome in humans worldwide. The two major virulence determinants of EHEC are the Shiga toxins (Stx and the type III secretion system (T3SS, including the injected effectors. Lack of a good model system hinders the study of EHEC virulence. Here, we investigated whether bovine and human intestinal xenografts in SCID mice can be useful for studying EHEC and host tissue interactions. Fully developed, germ-free human and bovine small intestine and colon were established by subcutaneous transplantation of human and bovine fetal gut into SCID mice. Xenografts were allowed to develop for 3–4 months and thereafter were infected by direct intraluminal inoculation of Stx-negative derivatives of EHEC O157:H7, strain EDL933. The small intestine and colon xenografts closely mimicked the respective native tissues. Upon infection, EHEC induced formation of typical attaching and effacing lesions and tissue damage that resembled hemorrhagic colitis in colon xenografts. By contrast, xenografts infected with an EHEC mutant deficient in T3SS remained undamaged. Furthermore, EHEC did not attach to or damage the epithelium of small intestinal tissue, and these xenografts remained intact. EHEC damaged the colon in a T3SS-dependent manner, and this model is therefore useful for studying the molecular details of EHEC interactions with live human and bovine intestinal tissue. Furthermore, we demonstrate that Stx and gut microflora are not essential for EHEC virulence in the human gut.

  2. Changes in Enteric Neurons of Small Intestine in a Rat Model of Irritable Bowel Syndrome with Diarrhea.

    Science.gov (United States)

    Li, Shan; Fei, Guijun; Fang, Xiucai; Yang, Xilin; Sun, Xiaohong; Qian, Jiaming; Wood, Jackie D; Ke, Meiyun

    2016-04-30

    Physical and/or emotional stresses are important factors in the exacerbation of symptoms in irritable bowel syndrome (IBS). Several lines of evidence support that a major impact of stress on the gastrointestinal tract occurs via the enteric nervous system. We aimed to evaluate histological changes in the submucosal plexus (SMP) and myenteric plexus (MP) of the distal ileum in concert with the intestinal motor function in a rat model of IBS with diarrhea. The rat model was induced by heterotypic chronic and acute stress (CAS). The intestinal transit was measured by administering powdered carbon by gastric gavage. Double immunohistochemical fluorescence staining with whole-mount preparations of SMP and MP of enteric nervous system was used to assess changes in expression of choline acetyltransferase, vasoactive intestinal peptide, or nitric oxide synthase in relation to the pan neuronal marker, anti-Hu. The intestinal transit ratio increased significantly from control values of 50.8% to 60.6% in the CAS group. The numbers of enteric ganglia and neurons in the SMP were increased in the CAS group. The proportions of choline acetyltransferase- and vasoactive intestinal peptide-immunoreactive neurons in the SMP were increased (82.1 ± 4.3% vs. 76.0 ± 5.0%, P = 0.021; 40.5 ± 5.9% vs 28.9 ± 3.7%, P = 0.001), while nitric oxide synthase-immunoreactive neurons in the MP were decreased compared with controls (23.3 ± 4.5% vs 32.4 ± 4.5%, P = 0.002). These morphological changes in enteric neurons to CAS might contribute to the dysfunction in motility and secretion in IBS with diarrhea.

  3. Dietary Putrescine Reduces the Anticarcinogenic Intestinal Activity of Sulindac in a Murine Model of Familial Adenomatous Polyposis

    Science.gov (United States)

    Ignatenko, Natalia A.; Besselsen, David G.; Basu Roy, Upal K.; Stringer, David E.; Blohm-Mangone, Karen A.; Padilla-Torres, Jose L.; Guillen-R, Jose M.; Gerner, Eugene W.

    2013-01-01

    The nonsteroidal antiinflammatory drug sulindac displays chemopreventive activity in patients with familial adenomatous polyposis (FAP). Sulindac metabolites induce apoptosis in colon tumor cells, in part, by a polyamine-dependent mechanism that can be suppressed with exogenous putrescine. To determine the relevance of this mechanism in animals, we treated ApcMin/+ mice, a model of human FAP, with sulindac alone or in combination with dietary putrescine. Sulindac increased steady-state RNA levels and enzymatic activity of the polyamine catabolic enzyme spermidine/spermine N1-acetyltransferase and intestinal levels of monoacetylspermidine, spermidine, and spermine in the small intestine of mice. Sulindac also decreased the activity of the biosynthetic enzyme ornithine decarboxylase but not adenosylmethionine decarboxylase (AMD). Dietary putrescine increased intestinal putrescine contents, whereas the combination of dietary putrescine and sulindac yielded the highest levels of intestinal putrescine and correlated with a statistically significant reduction in AMD enzyme activity. Dietary putrescine did not statistically significantly increase tumorigenesis, although it significantly increased the grade of adenoma dysplasia (P putrescine. These data suggest that sulindac exerts at least some of its anticarcinogenic effects in mice via a polyamine-dependent mechanism. Because high concentrations of putrescine can be found in certain dietary components, it may be advantageous to restrict dietary putrescine consumption in patients undergoing treatment with sulindac. PMID:17474863

  4. Glycoprotein A33 deficiency: a new mouse model of impaired intestinal epithelial barrier function and inflammatory disease

    Directory of Open Access Journals (Sweden)

    Benjamin B. Williams

    2015-08-01

    Full Text Available The cells of the intestinal epithelium provide a selectively permeable barrier between the external environment and internal tissues. The integrity of this barrier is maintained by tight junctions, specialised cell-cell contacts that permit the absorption of water and nutrients while excluding microbes, toxins and dietary antigens. Impairment of intestinal barrier function contributes to multiple gastrointestinal disorders, including food hypersensitivity, inflammatory bowel disease (IBD and colitis-associated cancer (CAC. Glycoprotein A33 (GPA33 is an intestinal epithelium-specific cell surface marker and member of the CTX group of transmembrane proteins. Roles in cell-cell adhesion have been demonstrated for multiple CTX family members, suggesting a similar function for GPA33 within the gastrointestinal tract. To test a potential requirement for GPA33 in intestinal barrier function, we generated Gpa33−/− mice and subjected them to experimental regimens designed to produce food hypersensitivity, colitis and CAC. Gpa33−/− mice exhibited impaired intestinal barrier function. This was shown by elevated steady-state immunosurveillance in the colonic mucosa and leakiness to oral TRITC-labelled dextran after short-term exposure to dextran sodium sulphate (DSS to injure the intestinal epithelium. Gpa33−/− mice also exhibited rapid onset and reduced resolution of DSS-induced colitis, and a striking increase in the number of colitis-associated tumours produced by treatment with the colon-specific mutagen azoxymethane (AOM followed by two cycles of DSS. In contrast, Gpa33−/− mice treated with AOM alone showed no increase in sporadic tumour formation, indicating that their increased tumour susceptibility is dependent on inflammatory stimuli. Finally, Gpa33−/− mice displayed hypersensitivity to food allergens, a common co-morbidity in humans with IBD. We propose that Gpa33−/− mice provide a valuable model to study the mechanisms

  5. Absence of intestinal inflammation and postoperative ileus in a mouse model of laparoscopic surgery

    NARCIS (Netherlands)

    Gomez-Pinilla, Pedro J.; Binda, Maria M.; Lissens, Ann; Di Giovangiulio, Martina; van Bree, Sjoerd H.; Nemethova, Andrea; Stakenborg, Nathalie; Farro, Giovanna; Bosmans, Goele; Matteoli, Gianluca; Deprest, Jan; Boeckxstaens, Guy E.

    2014-01-01

    Postoperative ileus (POI) is characterized by impaired gastrointestinal motility resulting from intestinal handling-associated inflammation. The introduction of laparoscopic surgery has dramatically reduced the duration of POI. However, it remains unclear to what extent this results in a reduction

  6. Deregulated Lipid Sensing by Intestinal CD36 in Diet-Induced Hyperinsulinemic Obese Mouse Model.

    Directory of Open Access Journals (Sweden)

    Marjorie Buttet

    Full Text Available The metabolic syndrome (MetS greatly increases risk of cardiovascular disease and diabetes and is generally associated with abnormally elevated postprandial triglyceride levels. We evaluated intestinal synthesis of triglyceride-rich lipoproteins (TRL in a mouse model of the MetS obtained by feeding a palm oil-rich high fat diet (HFD. By contrast to control mice, MetS mice secreted two populations of TRL. If the smaller size population represented 44% of total particles in the beginning of intestinal lipid absorption in MetS mice, it accounted for only 17% after 4 h due to the secretion of larger size TRL. The MetS mice displayed accentuated postprandial hypertriglyceridemia up to 3 h due to a defective TRL clearance. These alterations reflected a delay in lipid induction of genes for key proteins of TRL formation (MTP, L-FABP and blood clearance (ApoC2. These abnormalities associated with blunted lipid sensing by CD36, which is normally required to optimize jejunal formation of large TRL. In MetS mice CD36 was not downregulated by lipid in contrast to control mice. Treatment of controls with the proteosomal inhibitor MG132, which prevented CD36 downregulation, resulted in blunted lipid-induction of MTP, L-FABP and ApoC2 gene expression, as in MetS mice. Absence of CD36 sensing was due to the hyperinsulinemia in MetS mice. Acute insulin treatment of controls before lipid administration abolished CD36 downregulation, lipid-induction of TRL genes and reduced postprandial triglycerides (TG, while streptozotocin-treatment of MetS mice restored lipid-induced CD36 degradation and TG secretion. In vitro, insulin treatment abolished CD36-mediated up-regulation of MTP in Caco-2 cells. In conclusion, HFD treatment impairs TRL formation in early stage of lipid absorption via insulin-mediated inhibition of CD36 lipid sensing. This impairment results in production of smaller TRL that are cleared slowly from the circulation, which might contribute to the

  7. Analysis of Multi-Loop Control Structures of Dividing-Wall Distillation Columns Using a Fundamental Model

    Directory of Open Access Journals (Sweden)

    Salvador Tututi-Avila

    2014-02-01

    Full Text Available Dividing-wall columns (DWCs have significant potential as energy-efficient processes for the separation of multicomponent mixtures. However, in addition to an efficient steady state design, dynamics and control also play a major part for the success of a technology. This is especially so for complex distillation systems. This paper investigates the dynamics of a dividing wall column used for the separation of ternary mixtures. A detailed dynamic first principles-based model of the column I s developed in gPROMS. The model is used to generate data used for control loop pairing via the Relative Gain Array (RGA, and controller parameters are found by using Internal Model Control (IMC tuning. The best control structures for DWC systems, involving four different ternary mixtures, and two different feed compositions for each mixture, are investigated.

  8. In vivo perfusion assessment of an anastomosis surgery on porcine intestinal model (Conference Presentation)

    Science.gov (United States)

    Le, Hanh N. D.; Opferman, Justin; Decker, Ryan; Cheon, Gyeong W.; Kim, Peter C. W.; Kang, Jin U.; Krieger, Axel

    2016-04-01

    Anastomosis, the connection of two structures, is a critical procedure for reconstructive surgery with over 1 million cases/year for visceral indication alone. However, complication rates such as strictures and leakage affect up to 19% of cases for colorectal anastomoses and up to 30% for visceral transplantation anastomoses. Local ischemia plays a critical role in anastomotic complications, making blood perfusion an important indicator for tissue health and predictor for healing following anastomosis. In this work, we apply a real time multispectral imaging technique to monitor impact on tissue perfusion due to varying interrupted suture spacing and suture tensions. Multispectral tissue images at 470, 540, 560, 580, 670 and 760 nm are analyzed in conjunction with an empirical model based on diffuse reflectance process to quantify the hemoglobin oxygen saturation within the suture site. The investigated tissues for anastomoses include porcine small (jejunum and ileum) and large (transverse colon) intestines. Two experiments using interrupted suturing with suture spacing of 1, 2, and 3 mm and tension levels from 0 N to 2.5 N are conducted. Tissue perfusion at 5, 10, 20 and 30 min after suturing are recorded and compared with the initial normal state. The result indicates the contrast between healthy and ischemic tissue areas and assists the determination of suturing spacing and tension. Therefore, the assessment of tissue perfusion will permit the development and intra-surgical monitoring of an optimal suture protocol during anastomosis with less complications and improved functional outcome.

  9. Intestinal Transportations of Main Chemical Compositions of Polygoni Multiflori Radix in Caco-2 Cell Model

    Directory of Open Access Journals (Sweden)

    Jie Yu

    2014-01-01

    Full Text Available Context. Polygoni Multiflori Radix (PMR is originated from the root of Polygonum multiflorum Thunb. and used in oriental countries for centuries. However, little researches pay close attention to the absorption of its major constituents. Objective. Transepithelial transport of TSG, RL, PL, and four anthraquinones is carried out. Materials and Methods. Caco-2 cell monolayer, which represented a well-established model for the study of intestinal transport of nutrients and xenobiotics, was used in this paper. Results. The apparent permeability coefficients (Papp in the Caco-2 cell monolayers were TSG (2.372 × 10−9 < EG (2.391 × 10−9 < EN (2.483 × 10−9 < PL (4.917 × 10−9 < RN (1.707 × 10−8 < RL (1.778 × 10−8 < AE (1.952 × 10−8. Thus, RN, RL, and AE were considered partly absorbed, while other constituents were hardly absorbed. Discussion and Conclusion. Glycosides showed poor permeabilities than aglycones. In the meantime, TSG and EN gave out poor recovery rates in this assay, which indicated that TSG and EN may accumulate or metabolise in the Caco-2 cells. In silico prediction indicated that Gibbs energy (r=0.751, p<0.05 and heat of form (r=0.701, p<0.05 were strongly positively correlated with Papp.

  10. Intestinal Transportations of Main Chemical Compositions of Polygoni Multiflori Radix in Caco-2 Cell Model

    Science.gov (United States)

    Li, Na; Lin, Pei; Li, Yunfei; Mao, Xiaojian; Bao, Getuzhaori; Zhao, Ronghua

    2014-01-01

    Context. Polygoni Multiflori Radix (PMR) is originated from the root of Polygonum multiflorum Thunb. and used in oriental countries for centuries. However, little researches pay close attention to the absorption of its major constituents. Objective. Transepithelial transport of TSG, RL, PL, and four anthraquinones is carried out. Materials and Methods. Caco-2 cell monolayer, which represented a well-established model for the study of intestinal transport of nutrients and xenobiotics, was used in this paper. Results. The apparent permeability coefficients (P app) in the Caco-2 cell monolayers were TSG (2.372 × 10−9) < EG (2.391 × 10−9) < EN (2.483 × 10−9) < PL (4.917 × 10−9) < RN (1.707 × 10−8) < RL (1.778 × 10−8) < AE (1.952 × 10−8). Thus, RN, RL, and AE were considered partly absorbed, while other constituents were hardly absorbed. Discussion and Conclusion. Glycosides showed poor permeabilities than aglycones. In the meantime, TSG and EN gave out poor recovery rates in this assay, which indicated that TSG and EN may accumulate or metabolise in the Caco-2 cells. In silico prediction indicated that Gibbs energy (r = 0.751, p < 0.05) and heat of form (r = 0.701, p < 0.05) were strongly positively correlated with P app. PMID:24693324

  11. The role of the intestinal microvasculature in inflammatory bowel disease: studies with a modified Caco-2 model including endothelial cells resembling the intestinal barrier in vitro

    Science.gov (United States)

    Kasper, Jennifer Y; Hermanns, Maria Iris; Cavelius, Christian; Kraegeloh, Annette; Jung, Thomas; Danzebrink, Rolf; Unger, Ronald E; Kirkpatrick, Charles James

    2016-01-01

    The microvascular endothelium of the gut barrier plays a crucial role during inflammation in inflammatory bowel disease. We have modified a commonly used intestinal cell model based on the Caco-2 cells by adding microvascular endothelial cells (ISO-HAS-1). Transwell filters were used with intestinal barrier-forming Caco-2 cells on top and the ISO-HAS-1 on the bottom of the filter. The goal was to determine whether this coculture mimics the in vivo situation more closely, and whether the model is suitable to evaluate interactions of, for example, prospective nanosized drug vehicles or contrast agents with this coculture in a physiological and inflamed state as it would occur in inflammatory bowel disease. We monitored the inflammatory responsiveness of the cells (release of IL-8, soluble intercellular adhesion molecule 1, and soluble E-selectin) after exposure to inflammatory stimuli (lipopolysaccharide, TNF-α, INF-γ, IL1-β) and a nanoparticle (Ba/Gd: coprecipitated BaSO4 and Gd(OH)3), generally used as contrast agents. The barrier integrity of the coculture was evaluated via the determination of transepithelial electrical resistance and the apparent permeability coefficient (Papp) of NaFITC. The behavior of the coculture Caco-1/ISO-HAS-1 was compared to the respective monocultures Caco-2 and ISO-HAS-1. Based on transepithelial electrical resistance, the epithelial barrier integrity of the coculture remained stable during incubation with all stimuli, whereas the Papp decreased after exposure to the cytokine mixture (TNF-α, INF-γ, IL1-β, and Ba/Gd). Both the endothelial and epithelial monocultures showed a high inflammatory response in both the upper and lower transwell-compartments. However, in the coculture, inflammatory mediators were only detected on the epithelial side and not on the endothelial side. Thus in the coculture, based on the Papp, the epithelial barrier appears to prevent a potential inflammatory overreaction in the underlying endothelial cells

  12. The stomatogastric nervous system as a model for studying sensorimotor interactions in real-time closed-loop conditions

    Directory of Open Access Journals (Sweden)

    Nelly eDaur

    2012-03-01

    Full Text Available The perception of proprioceptive signals that report the internal state of the body is one of the essential tasks of the nervous system and helps to continuously adapt body movements to changing circumstances. Despite the impact of proprioceptive feedback on motor activity it has rarely been studied in conditions in which motor output and sensory activity interact as they do in behaving animals, i.e. in closed-loop conditions. The interaction of motor and sensory activities, however, can create emergent properties that may govern the functional characteristics of the system. We here demonstrate the use of a well-characterized model system for central pattern generation, the stomatogastric nervous system, for studying these properties in vitro. We created a real-time computer model of a single-cell muscle tendon organ in the gastric mill of the crab foregut that uses intracellular current injections to control the activity of the biological proprioceptor. The resulting motor output of a gastric mill motor neuron is then recorded intracellularly and fed into a simple muscle model consisting of a series of low-pass filters. The muscle output is used to activate a one-dimensional Hodgkin-Huxley type model of the muscle tendon organ in real-time, allowing closed-loop conditions. Model properties were either hand-tuned to achieve the best match with data from semi-intact muscle preparations, or an exhaustive search was performed to determine the best set of parameters. We report the real-time capabilities of our models, its performance and its interaction with the biological motor system.

  13. Insights into Campylobacter jejuni colonization of the mammalian intestinal tract using a novel mouse model of infection.

    Science.gov (United States)

    Stahl, Martin; Vallance, Bruce A

    2015-01-01

    A lack of relevant disease models for Campylobacter jejuni has long been an obstacle to research into this common enteric pathogen. We recently published that mice deficient in Single IgG Interleukin-1 related receptor (SIGIRR), a repressor of MyD88-dependent innate immune signaling, were highly susceptible to enteric infection by murine bacterial pathogens. Subsequently, we successfully employed these mice as an animal model for the human pathogen C. jejuni and gained substantial new insights into infection by this pathogen. The infected mice developed significant intestinal inflammation, primarily via TLR4 stimulation. Furthermore, the resulting gastroenteritis was dependent on C. jejuni pathogenesis as bacterial strains suffering mutations in key virulence factors were attenuated in causing disease. The ability to infect SIGIRR-deficient mice with C. jejuni sheds new light onto how these bacteria colonize the mucus layer of the intestinal tract, invade epithelial cells, and raises new prospects for studying the virulence strategies and pathogenesis of C. jejuni.

  14. Modeling the growth dynamics of multiple Escherichia coli strains in the pig intestine following intramuscular ampicillin treatment

    DEFF Research Database (Denmark)

    Ahmad, Amais; Zachariasen, Camilla; Christiansen, Lasse Engbo

    2016-01-01

    using a mathematical model to simulate the competitive growth of E. coli strains in a pig intestine under specified plasma concentration profiles of ampicillin. Results : In vitro growth results demonstrated that the resistant strains did not carry a fitness cost for their resistance, and that the most...... with ampicillin resistance in E. coli. Besides dosing factors, epidemiological factors (such as number of competing strains and bacterial excretion) influenced resistance development and need to be considered further in relation to optimal treatment strategies. The modeling approach used in the study is generic......Background : This study evaluated how dosing regimen for intramuscularly-administered ampicillin, composition of Escherichia coli strains with regard to ampicillin susceptibility, and excretion of bacteria from the intestine affected the level of resistance among Escherichia coli strains...

  15. Intestinal folate binding protein (FBP) and folate absorption in the suckling rat

    International Nuclear Information System (INIS)

    Mason, J.B.; Selhub, J.

    1986-01-01

    The folate in milk is bound to high affinity FBPs but it is unknown whether this binding affects intestinal transport of milk folate in the suckling rat. The authors examined the FBP activity of segments of the GI tract in fed and fasting states. Under fed conditions, the FBP activity in the mucosa of the stomach and proximal small intestine were similar (0.28 and 0.32 pMole folic acid binding/mg protein, N.S.). Both demonstrated less activity than the mucosa of the distal small intestine (1.31 pMole/mg protein, P 3 pteryolmonoglutamate (H 3 PGA) was examined in suckling rats by the intestinal loop model. Unbound H 3 PGA demonstrated greater lumenal disappearance in the proximal segment of the small intestine compared to the distal segment (79% vs. 56%, P 3 PGA demonstrated greater lumenal disappearance in the distal segment (36% vs. 21%, p < .005). That porton of FBP activity in the distal small intestine that disappears with fasting may represent FBP absorbed from the lumen of the intestine. The FBP-bound folate in milk appears to be absorbed in the suckling rat by a mechanism that favors the distal small intestine and is different from the mechanism responsible for absorption of the unbound folate

  16. Enterohemorrhagic Escherichia coli induce attaching and effacing lesions and hemorrhagic colitis in human and bovine intestinal xenograft models

    OpenAIRE

    Golan, Lilach; Gonen, Erez; Yagel, Simcha; Rosenshine, Ilan; Shpigel, Nahum Y.

    2010-01-01

    SUMMARY Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is an important cause of diarrhea, hemorrhagic colitis and hemolytic uremic syndrome in humans worldwide. The two major virulence determinants of EHEC are the Shiga toxins (Stx) and the type III secretion system (T3SS), including the injected effectors. Lack of a good model system hinders the study of EHEC virulence. Here, we investigated whether bovine and human intestinal xenografts in SCID mice can be useful for studying EHEC and...

  17. Quantum Structure of Field Theory and Standard Model Based on Infinity-Free Loop Regularization/renormalization

    Science.gov (United States)

    Wu, Yue-Liang

    2014-04-01

    To understand better the quantum structure of field theory and standard model in particle physics, it is necessary to investigate carefully the divergence structure in quantum field theories (QFTs) and work out a consistent framework to avoid infinities. The divergence has got us into trouble since developing quantum electrodynamics in 1930s. Its treatment via the renormalization scheme is satisfied not by all physicists, like Dirac and Feynman who have made serious criticisms. The renormalization group analysis reveals that QFTs can in general be defined fundamentally with the meaningful energy scale that has some physical significance, which motivates us to develop a new symmetry-preserving and infinity-free regularization scheme called loop regularization (LORE). A simple regularization prescription in LORE is realized based on a manifest postulation that a loop divergence with a power counting dimension larger than or equal to the space-time dimension must vanish. The LORE method is achieved without modifying original theory and leads the divergent Feynman loop integrals well-defined to maintain the divergence structure and meanwhile preserve basic symmetries of original theory. The crucial point in LORE is the presence of two intrinsic energy scales which play the roles of ultraviolet cutoff Mc and infrared cutoff μs to avoid infinities. As Mc can be made finite when taking appropriately both the primary regulator mass and number to be infinity to recover the original integrals, the two energy scales Mc and μs in LORE become physically meaningful as the characteristic energy scale and sliding energy scale, respectively. The key concept in LORE is the introduction of irreducible loop integrals (ILIs) on which the regularization prescription acts, which leads to a set of gauge invariance consistency conditions between the regularized tensor-type and scalar-type ILIs. An interesting observation in LORE is that the evaluation of ILIs with ultraviolet

  18. Demethoxycurcumin from Curcuma longa rhizome suppresses iNOS induction in an in vitro inflamed human intestinal mucosa model.

    Science.gov (United States)

    Somchit, Mayura; Changtam, Chatchawan; Kimseng, Rungruedi; Utaipan, Tanyarath; Lertcanawanichakul, Monthon; Suksamrarn, Apichart; Chunglok, Warangkana

    2014-01-01

    It is known that inducible nitric oxide synthase (iNOS)/nitric oxide (NO) plays an integral role during intestinal inflammation, an important factor for colon cancer development. Natural compounds from Curcuma longa L. (Zingiberaceae) have long been a potential source of bioactive materials with various beneficial biological functions. Among them, a major active curcuminoid, demethoxycurcumin (DMC) has been shown to possess anti-inflammatory properties in lipopolysaccharide (LPS)-activated macrophages or microglia cells. However, the role of DMC on iNOS expression and NO production in an in vitro inflamed human intestinal mucosa model has not yet been elucidated. This study concerned inhibitory effects on iNOS expression and NO production of DMC in inflamed human intestinal Caco-2 cells. An in vitro model was generated and inhibitory effects on NO production of DMC at 65 μM for 24-96 h were assessed by monitoring nitrite levels. Expression of iNOS mRNA and protein was also investigated. DMC significantly decreased NO secretion by 35-41% in our inflamed cell model. Decrease in NO production by DMC was concomitant with down-regulation of iNOS at mRNA and protein levels compared to proinflammatory cytokine cocktail and LPS-treated controls. Mechanism of action of DMC may be partly due to its potent inhibition of the iNOS pathway. Our findings suggest that DMC may have potential as a therapeutic agent against inflammation-related diseases, especially in the gut.

  19. Novel Polyfermentor intestinal model (PolyFermS for controlled ecological studies: validation and effect of pH.

    Directory of Open Access Journals (Sweden)

    Annina Zihler Berner

    Full Text Available In vitro gut fermentation modeling offers a useful platform for ecological studies of the intestinal microbiota. In this study we describe a novel Polyfermentor Intestinal Model (PolyFermS designed to compare the effects of different treatments on the same complex gut microbiota. The model operated in conditions of the proximal colon is composed of a first reactor containing fecal microbiota immobilized in gel beads, and used to continuously inoculate a set of parallel second-stage reactors. The PolyFermS model was validated with three independent intestinal fermentations conducted for 38 days with immobilized human fecal microbiota obtained from three child donors. The microbial diversity of reactor effluents was compared to donor feces using the HITChip, a high-density phylogenetic microarray targeting small subunit rRNA sequences of over 1100 phylotypes of the human gastrointestinal tract. Furthermore, the metabolic response to a decrease of pH from 5.7 to 5.5, applied to balance the high fermentative activity in inoculum reactors, was studied. We observed a reproducible development of stable intestinal communities representing major taxonomic bacterial groups at ratios similar to these in feces of healthy donors, a high similarity of microbiota composition produced in second-stage reactors within a model, and a high time stability of microbiota composition and metabolic activity over 38 day culture. For all tested models, the pH-drop of 0.2 units in inoculum reactors enhanced butyrate production at the expense of acetate, but was accompanied by a donor-specific reorganization of the reactor community, suggesting a concerted metabolic adaptation and trigger of community-specific lactate or acetate cross-feeding pathways in response to varying pH. Our data showed that the PolyFermS model allows the stable cultivation of complex intestinal microbiota akin to the fecal donor and can be developed for the direct comparison of different

  20. Developments in Methods for Measuring the Intestinal Absorption of Nanoparticle-Bound Drugs.

    Science.gov (United States)

    Liu, Wei; Pan, Hao; Zhang, Caiyun; Zhao, Liling; Zhao, Ruixia; Zhu, Yongtao; Pan, Weisan

    2016-07-21

    With the rapid development of nanotechnology, novel drug delivery systems comprising orally administered nanoparticles (NPs) have been paid increasing attention in recent years. The bioavailability of orally administered drugs has significant influence on drug efficacy and therapeutic dosage, and it is therefore imperative that the intestinal absorption of oral NPs be investigated. This review examines the various literature on the oral absorption of polymeric NPs, and provides an overview of the intestinal absorption models that have been developed for the study of oral nanoparticles. Three major categories of models including a total of eight measurement methods are described in detail (in vitro: dialysis bag, rat gut sac, Ussing chamber, cell culture model; in situ: intestinal perfusion, intestinal loops, intestinal vascular cannulation; in vivo: the blood/urine drug concentration method), and the advantages and disadvantages of each method are contrasted and elucidated. In general, in vitro and in situ methods are relatively convenient but lack accuracy, while the in vivo method is troublesome but can provide a true reflection of drug absorption in vivo. This review summarizes the development of intestinal absorption experiments in recent years and provides a reference for the systematic study of the intestinal absorption of nanoparticle-bound drugs.

  1. A New Open-Loop Fiber Optic Gyro Error Compensation Method Based on Angular Velocity Error Modeling

    Directory of Open Access Journals (Sweden)

    Yanshun Zhang

    2015-02-01

    Full Text Available With the open-loop fiber optic gyro (OFOG model, output voltage and angular velocity can effectively compensate OFOG errors. However, the model cannot reflect the characteristics of OFOG errors well when it comes to pretty large dynamic angular velocities. This paper puts forward a modeling scheme with OFOG output voltage  and temperature  as the input variables and angular velocity error  as the output variable. Firstly, the angular velocity error  is extracted from OFOG output signals, and then the output voltage , temperature  and angular velocity error  are used as the learning samples to train a Radial-Basis-Function (RBF neural network model. Then the nonlinear mapping model over T,  and  is established and thus  can be calculated automatically to compensate OFOG errors according to  and . The results of the experiments show that the established model can be used to compensate the nonlinear OFOG errors. The maximum, the minimum and the mean square error of OFOG angular velocity are decreased by ,  and  relative to their initial values, respectively. Compared with the direct modeling of gyro angular velocity, which we researched before, the experimental results of the compensating method proposed in this paper are further reduced by ,  and , respectively, so the performance of this method is better than that of the direct modeling for gyro angular velocity.

  2. A new open-loop fiber optic gyro error compensation method based on angular velocity error modeling.

    Science.gov (United States)

    Zhang, Yanshun; Guo, Yajing; Li, Chunyu; Wang, Yixin; Wang, Zhanqing

    2015-02-27

    With the open-loop fiber optic gyro (OFOG) model, output voltage and angular velocity can effectively compensate OFOG errors. However, the model cannot reflect the characteristics of OFOG errors well when it comes to pretty large dynamic angular velocities. This paper puts forward a modeling scheme with OFOG output voltage u and temperature T as the input variables and angular velocity error Δω as the output variable. Firstly, the angular velocity error Δω is extracted from OFOG output signals, and then the output voltage u, temperature T and angular velocity error Δω are used as the learning samples to train a Radial-Basis-Function (RBF) neural network model. Then the nonlinear mapping model over T, u and Δω is established and thus Δω can be calculated automatically to compensate OFOG errors according to T and u. The results of the experiments show that the established model can be used to compensate the nonlinear OFOG errors. The maximum, the minimum and the mean square error of OFOG angular velocity are decreased by 97.0%, 97.1% and 96.5% relative to their initial values, respectively. Compared with the direct modeling of gyro angular velocity, which we researched before, the experimental results of the compensating method proposed in this paper are further reduced by 1.6%, 1.4% and 1.42%, respectively, so the performance of this method is better than that of the direct modeling for gyro angular velocity.

  3. An evolutionary-network model reveals stratified interactions in the V3 loop of the HIV-1 envelope.

    Directory of Open Access Journals (Sweden)

    Art F Y Poon

    2007-11-01

    Full Text Available The third variable loop (V3 of the human immunodeficiency virus type 1 (HIV-1 envelope is a principal determinant of antibody neutralization and progression to AIDS. Although it is undoubtedly an important target for vaccine research, extensive genetic variation in V3 remains an obstacle to the development of an effective vaccine. Comparative methods that exploit the abundance of sequence data can detect interactions between residues of rapidly evolving proteins such as the HIV-1 envelope, revealing biological constraints on their variability. However, previous studies have relied implicitly on two biologically unrealistic assumptions: (1 that founder effects in the evolutionary history of the sequences can be ignored, and; (2 that statistical associations between residues occur exclusively in pairs. We show that comparative methods that neglect the evolutionary history of extant sequences are susceptible to a high rate of false positives (20%-40%. Therefore, we propose a new method to detect interactions that relaxes both of these assumptions. First, we reconstruct the evolutionary history of extant sequences by maximum likelihood, shifting focus from extant sequence variation to the underlying substitution events. Second, we analyze the joint distribution of substitution events among positions in the sequence as a Bayesian graphical model, in which each branch in the phylogeny is a unit of observation. We perform extensive validation of our models using both simulations and a control case of known interactions in HIV-1 protease, and apply this method to detect interactions within V3 from a sample of 1,154 HIV-1 envelope sequences. Our method greatly reduces the number of false positives due to founder effects, while capturing several higher-order interactions among V3 residues. By mapping these interactions to a structural model of the V3 loop, we find that the loop is stratified into distinct evolutionary clusters. We extend our model to

  4. Concord and Niagara Grape Juice and Their Phenolics Modify Intestinal Glucose Transport in a Coupled in Vitro Digestion/Caco-2 Human Intestinal Model

    Directory of Open Access Journals (Sweden)

    Sydney Moser

    2016-07-01

    Full Text Available While the potential of dietary phenolics to mitigate glycemic response has been proposed, the translation of these effects to phenolic rich foods such as 100% grape juice (GJ remains unclear. Initial in vitro screening of GJ phenolic extracts from American grape varieties (V. labrusca; Niagara and Concord suggested limited inhibitory capacity for amylase and α-glucosidase (6.2%–11.5% inhibition; p < 0.05. Separately, all GJ extracts (10–100 µM total phenolics did reduce intestinal trans-epithelial transport of deuterated glucose (d7-glu and fructose (d7-fru by Caco-2 monolayers in a dose-dependent fashion, with 60 min d7-glu/d7-fru transport reduced 10%–38% by GJ extracts compared to control. To expand on these findings by assessing the ability of 100% GJ to modify starch digestion and glucose transport from a model starch-rich meal, 100% Niagara and Concord GJ samples were combined with a starch rich model meal (1:1 and 1:2 wt:wt and glucose release and transport were assessed in a coupled in vitro digestion/Caco-2 cell model. Digestive release of glucose from the starch model meal was decreased when digested in the presence of GJs (5.9%–15% relative to sugar matched control. Furthermore, transport of d7-glu was reduced 10%–38% by digesta containing bioaccessible phenolics from Concord and Niagara GJ compared to control. These data suggest that phenolics present in 100% GJ may alter absorption of monosaccharides naturally present in 100% GJ and may potentially alter glycemic response if consumed with a starch rich meal.

  5. Contribution of H. pylori and smoking trends to US incidence of intestinal-type noncardia gastric adenocarcinoma: a microsimulation model.

    Directory of Open Access Journals (Sweden)

    Jennifer M Yeh

    Full Text Available Although gastric cancer has declined dramatically in the US, the disease remains the second leading cause of cancer mortality worldwide. A better understanding of reasons for the decline can provide important insights into effective preventive strategies. We sought to estimate the contribution of risk factor trends on past and future intestinal-type noncardia gastric adenocarcinoma (NCGA incidence.We developed a population-based microsimulation model of intestinal-type NCGA and calibrated it to US epidemiologic data on precancerous lesions and cancer. The model explicitly incorporated the impact of Helicobacter pylori and smoking on disease natural history, for which birth cohort-specific trends were derived from the National Health and Nutrition Examination Survey (NHANES and National Health Interview Survey (NHIS. Between 1978 and 2008, the model estimated that intestinal-type NCGA incidence declined 60% from 11.0 to 4.4 per 100,000 men, <3% discrepancy from national statistics. H. pylori and smoking trends combined accounted for 47% (range = 30%-58% of the observed decline. With no tobacco control, incidence would have declined only 56%, suggesting that lower smoking initiation and higher cessation rates observed after the 1960s accelerated the relative decline in cancer incidence by 7% (range = 0%-21%. With continued risk factor trends, incidence is projected to decline an additional 47% between 2008 and 2040, the majority of which will be attributable to H. pylori and smoking (81%; range = 61%-100%. Limitations include assuming all other risk factors influenced gastric carcinogenesis as one factor and restricting the analysis to men.Trends in modifiable risk factors explain a significant proportion of the decline of intestinal-type NCGA incidence in the US, and are projected to continue. Although past tobacco control efforts have hastened the decline, full benefits will take decades to be realized, and further discouragement of smoking and

  6. FETAL METABOLIC PROGRAMMING OF THE SMALL INTESTINE IN A COPENHAGEN SHEEP MODEL

    DEFF Research Database (Denmark)

    Axel, Anne Marie Dixen; Khanal, Prabhat; Kongsted, Anna Hauntoft

    Fetal metabolic programming states that early life nutrition is implicated with the risk of later disease development and both under- and overnutrition during gestation might predispose individuals to develop obesity or diabetes later in life. Obesity operations called “gastric bypass” operations...... have shown unexpected involvement of the small intestine in diabetes pathophysiology as it in most cases result in a complete resolution of the diabetes before weight loss. Therefore we hypothesize that the small intestine is a subject of metabolic programming and that this programming can predispose...... effects on gene-expression, however the results vary between genes. These observations suggest that small intestine function has been programmed by the late-gestation Low or High diet at gene expression level, whereas the physiological metabolic functions has mainly been affected by the HCHF diet...

  7. Protective effects of L-carnitine on intestinal ischemia/reperfusion injury in a rat model.

    Science.gov (United States)

    Yuan, Yong; Guo, Hao; Zhang, Yi; Zhou, Dong; Gan, Ping; Liang, Dao Ming; Chen, Jia Yong

    2011-04-04

    Ischemia/reperfusion (IR) injury of the intestine is a major problem in abdominal pathological condition and is associated with a high morbidity and mortality. The purpose of the study is to determine whether the L-carnitine can prevent the harmful effects of small intestinal IR injury in rats. Thirty Sprague-Dawley rats were randomly divided into three groups. Sham operated group (S), for shamoperated, the IR group for rats submitted to 45-minute of intestinal ischemia and 2-hour reperfusion, and IR+L group for those IR group treated with L-carnitine before reperfusion. All the rats were given EmGFP labelled E. coli DH5α through gavage 2-hour before the operative procedure. Afterwards the bacterial translocation (BT) from mesenteric lymph nodes (MLN), liver, spleen, lung and portal vein blood were detected. And the colony forming units/g (CFU/g) were counted. The TNF-α, IL-1β, IL-6, and IL-10 in serum were measured by ELISA. The morphometric study was measured by Chius classification. The levels of BT were higher in the IR group than IR+L group (P E. coli DH5α was hardly detected in the S group. The IR+L rats had enhancement of IL-10 and suppressed production of serum TNF-α, IL-1β and IL-6, compared to IR group rats (P L-carnitine pretreatment has a positive effect on reducing levels of BT, on inhibiting secretion of proinflammatory cytokines, and on lessening intestinal mucosa injury during small intestinal IR injury. L-carnitine; Ischemia/reperfusion injury; Intestine.

  8. Reactions between a 1/2⟨111⟩ screw dislocation and ⟨100⟩ interstitial dislocation loops in alpha-iron modelled at atomic scale

    Science.gov (United States)

    Terentyev, D.; Bacon, D. J.; Osetsky, Yu. N.

    2010-03-01

    Interstitial dislocation loops with Burgers vector of ? type are observed in α-iron irradiated by neutrons or heavy ions, and their population increases with increasing temperature. Their effect on motion of a ? edge dislocation was reported earlier 1. Results are presented of a molecular dynamics study of interactions between a ? screw dislocation and ? loops in iron at temperature in the range 100 to 600 K. A variety of reaction mechanisms and outcomes are observed and classified in terms of the resulting dislocation configuration and the maximum stress required for the dislocation to break away. The highest obstacle resistance arises when the loop is absorbed to form a helical turn on the screw dislocation line, for the dislocation cannot glide away until the turn closes and a loop is released with the same Burgers vector as the line. Other than one situation found, in which no dislocation-loop reaction occurs, the weakest obstacle strength is found when the original ? loop is restored at the end of the reaction. The important role of the cross-slip and the influence of model boundary conditions are emphasised and demonstrated by examples.

  9. Challenges of culturing human norovirus in three-dimensional organoid intestinal cell culture models.

    Directory of Open Access Journals (Sweden)

    Efstathia Papafragkou

    Full Text Available Human noroviruses are the most common cause of acute gastroenteritis worldwide. Recently, cell culture systems have been described using either human embryonic intestinal epithelial cells (Int-407 or human epithelial colorectal adenocarcinoma cells (Caco-2 growing on collagen-I porous micro carrier beads in a rotating bioreactor under conditions of physiological fluid shear. Here, we describe the efforts from two independent laboratories to implement this three dimensional (3D cell culture system for the replication of norovirus. Int-407 and Caco-2 were grown in a rotating bioreactor for up to 28 days. Prior to infection, cells were screened for the presence of microvilli by electron microscopy and stained for junction proteins (zonula occludens-1, claudin-1, and β-catenin. Differentiated 3D cells were transferred to 24-well plates and infected with bacteria-free filtrates of various norovirus genotypes (GI.1, GI.3, GI.8, GII.2, GII.4, GII.7, and GII.8. At 12 h, 24 h, and 48 h post inoculation, viral RNA from both cells and supernatants were collected and analyzed for norovirus RNA by real-time reverse transcription PCR. Despite observations of high expression of junction proteins and microvilli development in stained thin sections, our data suggest no significant increase in viral titer based on norovirus RNA copy number during the first 48 h after inoculation for the different samples and virus culture conditions tested. Our combined efforts demonstrate that 3D cell culture models using Int-407 or Caco-2 cells do not support norovirus replication and highlight the complexity and difficulty of developing a reproducible in vitro cell culture system for human norovirus.

  10. An ex-vivo human intestinal model to study Entamoeba histolytica pathogenesis.

    Directory of Open Access Journals (Sweden)

    Devendra Bansal

    Full Text Available Amoebiasis (a human intestinal infection affecting 50 million people every year is caused by the protozoan parasite Entamoeba histolytica. To study the molecular mechanisms underlying human colon invasion by E. histolytica, we have set up an ex vivo human colon model to study the early steps in amoebiasis. Using scanning electron microscopy and histological analyses, we have established that E. histolytica caused the removal of the protective mucus coat during the first two hours of incubation, detached the enterocytes, and then penetrated into the lamina propria by following the crypts of Lieberkühn. Significant cell lysis (determined by the release of lactodehydrogenase and inflammation (marked by the secretion of pro-inflammatory molecules such as interleukin 1 beta, interferon gamma, interleukin 6, interleukin 8 and tumour necrosis factor were detected after four hours of incubation. Entamoeba dispar (a closely related non-pathogenic amoeba that also colonizes the human colon was unable to invade colonic mucosa, lyse cells or induce an inflammatory response. We also examined the behaviour of trophozoites in which genes coding for known virulent factors (such as amoebapores, the Gal/GalNAc lectin and the cysteine protease 5 (CP-A5, which have major roles in cell death, adhesion (to target cells or mucus and mucus degradation, respectively were silenced, together with the corresponding tissue responses. Our data revealed that the signalling via the heavy chain Hgl2 or via the light chain Lgl1 of the Gal/GalNAc lectin is not essential to penetrate the human colonic mucosa. In addition, our study demonstrates that E. histolytica silenced for CP-A5 does not penetrate the colonic lamina propria and does not induce the host's pro-inflammatory cytokine secretion.

  11. Dynameomics: data-driven methods and models for utilizing large-scale protein structure repositories for improving fragment-based loop prediction.

    Science.gov (United States)

    Rysavy, Steven J; Beck, David A C; Daggett, Valerie

    2014-11-01

    Protein function is intimately linked to protein structure and dynamics yet experimentally determined structures frequently omit regions within a protein due to indeterminate data, which is often due protein dynamics. We propose that atomistic molecular dynamics simulations provide a diverse sampling of biologically relevant structures for these missing segments (and beyond) to improve structural modeling and structure prediction. Here we make use of the Dynameomics data warehouse, which contains simulations of representatives of essentially all known protein folds. We developed novel computational methods to efficiently identify, rank and retrieve small peptide structures, or fragments, from this database. We also created a novel data model to analyze and compare large repositories of structural data, such as contained within the Protein Data Bank and the Dynameomics data warehouse. Our evaluation compares these structural repositories for improving loop predictions and analyzes the utility of our methods and models. Using a standard set of loop structures, containing 510 loops, 30 for each loop length from 4 to 20 residues, we find that the inclusion of Dynameomics structures in fragment-based methods improves the quality of the loop predictions without being dependent on sequence homology. Depending on loop length, ∼ 25-75% of the best predictions came from the Dynameomics set, resulting in lower main chain root-mean-square deviations for all fragment lengths using the combined fragment library. We also provide specific cases where Dynameomics fragments provide better predictions for NMR loop structures than fragments from crystal structures. Online access to these fragment libraries is available at http://www.dynameomics.org/fragments. © 2014 The Protein Society.

  12. Administration of Protein kinase D1 induce an immunomodulatory effect on lipopolysaccharide-induced intestinal inflammation in a co-culture model of intestinal epithelial Caco-2 cells and RAW 264.7 macrophage cells

    DEFF Research Database (Denmark)

    Nielsen, Ditte Søvsø Gundelund; Fredborg, Marlene; Andersen, Vibeke

    2017-01-01

    the effects of human PKD1 in relation to intestinal inflammation, using a co-culture model of intestinal epithelial Caco-2 cells and RAW264.7 macrophages. An inflammatory response was induced in the macrophages by lipopolysaccharide (LPS), upregulating the expression of tumour necrosis factor alpha (TNF......-α), interleukin- (IL-) 1β, and IL-6 besides increasing the secretion of TNF-α protein. The effect of administering PKD1 to Caco-2 was evaluated in relation to both amelioration of inflammation and the ability to suppress inflammation initiation. Administration of PKD1 (10–100 ng/ml) following induction...

  13. Reprodaetion of an animal model of multiple intestinal injuries mimicking "lethal triad" caused by severe penetrating abdominal trauma

    Directory of Open Access Journals (Sweden)

    Peng-fei WANG

    2011-03-01

    Full Text Available Objective To reproduce an animal model of multi-intestinal injuries with "lethal triad" characterized by low body temperature,acidosis and coagulopathy.Methods Six female domestic outbred pigs were anesthetized,and the carotid artery and jugular vein were cannulated for monitoring the blood pressure and heart rate and for infusion of fluid.The animals were shot with a gun to create a severe penetrating abdominal trauma.Immediately after the shooting,50% of total blood volume(35ml/kg hemorrhage was drawn from the carotid artery in 20min.After a 40min shock period,4h of pre-hospital phase was mimicked by normal saline(NS resuscitation to maintain systolic blood pressure(SBP > 80mmHg or mean arterial pressure(MAP > 60mmHg.When SBP > 80mmHg or MAP > 60mmHg,no fluid infusion or additional bleeding was given.Hemodynamic parameters were recorded,and pathology of myocardium,lung,small intestine and liver was observed.Results There were multiple intestinal perforations(8-10 site injuries/pig leading to intra-abdominal contamination,mesenteric injury(1-2 site injuries/pig resulted in partial intestinal ischemia and intra-abdominal hemorrhage,and no large colon and mesenteric vascular injury.One pig died before the completion of the model establishment(at the end of pre-hospital resuscitation.The typical symptoms of trauma-induced hemorrhagic shock were observed in survival animals.Low temperature(33.3±0.5℃,acidosis(pH=7.242±0.064,and coagulopathy(protrombin time and activated partial thromboplasting time prolonged were observed after pre-hospital resuscitation.Pathology showed that myocardium,lung,small intestine and liver were severely injured.Conclusions A new model,simulating three stages of "traumatic hemorrhagic shock,pre-hospital recovery and hospital treatment" and inducing the "lethal triad" accompanied with abdominal pollution,has been successfully established.This model has good stability and high reproducibility.The survival animals can be

  14. The Effect of Lactulose on the Composition of the Intestinal Microbiota and Short-chain Fatty Acid Production in Human Volunteers and a Computer-controlled Model of the Proximal Large Intestine

    NARCIS (Netherlands)

    Venema, K.; Nuenen, M.H.M.C. van; Heuvel, E.G. van den; Pool, W.; Vossen, J.M.B.M. van der

    2003-01-01

    The objective of this study was to compare the in vivo effect of lactulose on faecal parameters with the effect in a dynamic, computer-controlled in vitro model of the proximal large intestine (TIM-2). Faecal samples from 10 human volunteers collected before (non-adapted) and after 1 week of

  15. Efeitos hemodinâmicos e metabólicos iniciais da perfusão hipotérmica intestinal in situ.: avaliação de um novo modelo canino de autotransplante intestinal Initial hemodynamic and metabolic effects of intestinal hypothermic perfusion in situ: an alternative model of canine intestinal autotransplantation

    Directory of Open Access Journals (Sweden)

    Ruy Jorge Cruz Junior

    2004-08-01

    , hemoglobina assim como na temperatura central. CONCLUSÃO: O modelo de autotransplante intestinal é extremamente útil e de fácil execução, para a avaliação inicial de soluções de preservação e/ou drogas antioxidantes, comumente utilizadas no transplante de intestino.Intestinal transplantation is an acceptable therapy for children and adults with short bowel syndrome. The great majority of large animal experimental models of intestinal transplantation are complex and take a lot of time to be performed. In this study, we developed an alternative model of intestinal autotransplantation and evaluate the initial impact of isolated hypothermic intestinal perfusion with Ringer’s lactate solution on hemodynamic and metabolic parameters. METHODS: Six pentobarbital anesthetized mongrel dogs were used in this study (22,8±1,4 Kg. Systemic hemodynamic were evaluated through a Swan-Ganz and arterial catheters; while gastrointestinal tract perfusion by superior mesenteric vein blood flow (SMVBF, ultrasonic flowprobe and intestinal mucosal pCO2 (pCO2-int and pCO2-gap, gas tonometry. Initially, the proximal jejunum and distal ileum were transected; at the basis of the mesentery excepting the superior mesenteric artery and vein. The small bowel was then perfused in situ with cold (4ºC Ringer’s lactate solution for 30 minutes, with an automatic pump. The animals where observed for 120 minutes after reperfusion. Blood samples were collected from thoracic aorta for gas blood analysis. RESULTS: Hypothermic intestinal perfusion induced a partial reduction on SMVBF, only in the first 30 min of reperfusion (398±102,8 to 587±70,9 ml/min and an increase on pCO2-gap (2±2,7 to 29,8±6 mmHg. During the experimental protocol, we did not observe significant alterations on systemic hemodynamic or metabolic parameters (MAP, CO, pH, base excess and hemoglobin levels as well as on central core temperature. CONCLUSION: The model of intestinal transplantation is very useful to test different

  16. COMMUNICATION: Toward closed-loop optimization of deep brain stimulation for Parkinson's disease: concepts and lessons from a computational model

    Science.gov (United States)

    Feng, Xiao-jiang; Greenwald, Brian; Rabitz, Herschel; Shea-Brown, Eric; Kosut, Robert

    2007-06-01

    Deep brain stimulation (DBS) of the subthalamic nucleus with periodic, high-frequency pulse trains is an increasingly standard therapy for advanced Parkinson's disease. Here, we propose that a closed-loop global optimization algorithm may identify novel DBS waveforms that could be more effective than their high-frequency counterparts. We use results from a computational model of the Parkinsonian basal ganglia to illustrate general issues relevant to eventual clinical or experimental tests of such an algorithm. Specifically, while the relationship between DBS characteristics and performance is highly complex, global search methods appear able to identify novel and effective waveforms with convergence rates that are acceptably fast to merit further investigation in laboratory or clinical settings.

  17. Closed Loop Subspace Identification

    Directory of Open Access Journals (Sweden)

    Geir W. Nilsen

    2005-07-01

    Full Text Available A new three step closed loop subspace identifications algorithm based on an already existing algorithm and the Kalman filter properties is presented. The Kalman filter contains noise free states which implies that the states and innovation are uneorre lated. The idea is that a Kalman filter found by a good subspace identification algorithm will give an output which is sufficiently uncorrelated with the noise on the output of the actual process. Using feedback from the output of the estimated Kalman filter in the closed loop system a subspace identification algorithm can be used to estimate an unbiased model.

  18. Intestinal tumorigenesis is not affected by progesterone signaling in rodent models

    NARCIS (Netherlands)

    Heijmans, Jarom; Muncan, Vanesa; Jacobs, Rutger J.; de Jonge-Muller, Eveline S. M.; Graven, Laura; Biemond, Izak; Ederveen, Antwan G.; Groothuis, Patrick G.; Mosselman, Sietse; Hardwick, James C.; Hommes, Daniel W.; van den Brink, Gijs R.

    2011-01-01

    Clinical data suggest that progestins have chemopreventive properties in the development of colorectal cancer. We set out to examine a potential protective effect of progestins and progesterone signaling on colon cancer development. In normal and neoplastic intestinal tissue, we found that the

  19. Human intestinal P-glycoprotein activity estimated by the model substrate digoxin

    DEFF Research Database (Denmark)

    Larsen, U L; Hyldahl Olesen, L; Nyvold, Charlotte Guldborg

    2007-01-01

    P-glycoprotein (Pgp) plays a part in the intestinal uptake of xenobiotics and has been associated with susceptibility to ulcerative colitis. The aim of this study was to examine Pgp activity in relation to age, gender, medical treatment (rifampicin or ketoconazole) and the multidrug resistance (MDR...

  20. Intestinal capacity to digest and absorb carbohydrates is maintained in a rat model of cholestasis

    NARCIS (Netherlands)

    Los, E. Leonie; Wolters, Henk; Stellaard, Frans; Kuipers, Folkert; Verkade, Henkjan J.; Rings, Edmond H. H. M.

    Cholestasis is associated with systemic accumulation of bile salts and with deficiency of bile in the intestinal lumen. During the past years bile salts have been identified as signaling molecules that regulate lipid, glucose, and energy metabolism. Bile salts have also been shown to activate

  1. Changes of intestinal mucosa in hand-fed rats-model for human coeliac disease

    Czech Academy of Sciences Publication Activity Database

    Kozáková, Hana; Štěpánková, Renata; Kolínská, Jiřina; Tučková, Ludmila; Tlaskalová, Helena

    1998-01-01

    Roč. 36, č. 4 (1998), s. 336 ISSN 0044-2771. [European Intestinal Transport Group Meeting /15./. Sundvollen, 17.05.1998-21.05.1998] R&D Projects: GA ČR GA303/96/1256; GA ČR GA311/97/0784; GA MZd IZ3761 Subject RIV: EC - Immunology Impact factor: 0.890, year: 1998

  2. Higher dimensional loop quantum cosmology

    International Nuclear Information System (INIS)

    Zhang, Xiangdong

    2016-01-01

    Loop quantum cosmology (LQC) is the symmetric sector of loop quantum gravity. In this paper, we generalize the structure of loop quantum cosmology to the theories with arbitrary spacetime dimensions. The isotropic and homogeneous cosmological model in n + 1 dimensions is quantized by the loop quantization method. Interestingly, we find that the underlying quantum theories are divided into two qualitatively different sectors according to spacetime dimensions. The effective Hamiltonian and modified dynamical equations of n + 1 dimensional LQC are obtained. Moreover, our results indicate that the classical big bang singularity is resolved in arbitrary spacetime dimensions by a quantum bounce. We also briefly discuss the similarities and differences between the n + 1 dimensional model and the 3 + 1 dimensional one. Our model serves as a first example of higher dimensional loop quantum cosmology and offers the possibility to investigate quantum gravity effects in higher dimensional cosmology. (orig.)

  3. Effect of adenine on bacterial translocation using technetium-99m labeled E. coli in an intestinal obstruction model in rats

    International Nuclear Information System (INIS)

    Ugur Oflaz; Fatma Yurt Lambrecht; Osman Yilmaz; Cetin Pekcetin

    2013-01-01

    This study aims to investigate effects of adenine on bacterial translocation (BT) using 99m Tc-labeled E. coli in an intestinal obstruction rat model. In the study twenty-one rats were used. The rats were divided into three groups according to different feeding patterns. The control group (CG) was fed with a standard chow diet for 7 days. Group A1 and group A2 were fed with adenine supplemented chow diet for 7 days. At the end of the feeding period, after all groups was submitted intestinal obstruction. 99m Tc-E. coli was injected into the rats' terminal ileum under anesthetic. The rats were sacrificed under aseptic conditions at 24th h after the surgery. The uptake of 99m Tc-E. coli was determined in organs such as the liver, mesenteric lymph nodes, spleen and ileum. Group A1 and group A2 results show that the uptake of 99m Tc-E. coli decreased in the blood and organs comparing to the CG. As a result, it was observed that adenine reduced the level of BT when compared with CG. The beneficial effect of adenine on BT in intestinal obstruction was observed. However, further studies are needed to more clearly assess how this benefit can be achieved. (author)

  4. Loop quantum cosmology: Recent progress

    Indian Academy of Sciences (India)

    Aspects of the full theory of loop quantum gravity can be studied in a simpler context by reducing to symmetric models like cosmological ones. This leads to several applications where loop effects play a significant role when one is sensitive to the quantum regime. As a consequence, the structure of and the approach to ...

  5. Intestinal alkaline phosphatase administration in newborns decreases systemic inflammatory cytokine expression in a neonatal necrotizing enterocolitis rat model.

    Science.gov (United States)

    Rentea, Rebecca M; Liedel, Jennifer L; Fredrich, Katherine; Welak, Scott R; Pritchard, Kirkwood A; Oldham, Keith T; Simpson, Pippa M; Gourlay, David M

    2012-10-01

    Supplementation of intestinal alkaline phosphatase (IAP), an endogenous protein expressed in the intestines, decreases the severity of necrotizing enterocolitis (NEC)-associated intestinal injury and permeability. We hypothesized that IAP administration is protective in a dose-dependent manner of the inflammatory response in a neonatal rat model. Pre- and full-term newborn Sprague-Dawley rat pups were sacrificed on day of life 3. Control pups were vaginally delivered and dam fed. Preterm pups were delivered via cesarean section and exposed to intermittent hypoxia and formula feeds containing lipopolysaccharide (NEC) with and without IAP. Three different standardized doses were administered to a group of pups treated with 40, 4, and 0.4U/kg of bovine IAP (NEC+IAP40, IAP4, or IAP0.4U). Reverse transcription-real-time polymerase chain reaction (RT-PCR) for inducible nitric oxide synthase (iNOS) and tumor necrosis factor (TNF)-α on liver and lung tissues and serum cytokine analysis for interleukin (IL)-1β, IL-6, IL-10, and TNF-α were performed. Data were analyzed by Kruskal-Wallis and Mann-Whitney tests, expressed as mean±standard error of the mean and P≤0.05 considered significant. Levels of cytokines IL-1β, IL-6, and TNF-α increased significantly in NEC versus control, returning to control levels with increasing doses of supplemental enteral IAP. Hepatic and pulmonary TNF-α and iNOS messenger ribonucleic acid expressions increased in NEC, and the remaining elevated despite IAP supplementation. Proinflammatory cytokine expression is increased systemically with intestinal NEC injury. Administration of IAP significantly reduces systemic proinflammatory cytokine expression in a dose-dependent manner. Early supplemental enteral IAP may reduce NEC-related injury and be useful for reducing effects caused by a proinflammatory cascade. Copyright © 2012 Elsevier Inc. All rights reserved.

  6. Discrete and ultradiscrete models for biological rhythms comprising a simple negative feedback loop.

    Science.gov (United States)

    Gibo, Shingo; Ito, Hiroshi

    2015-08-07

    Many biological rhythms are generated by negative feedback regulation. Griffith (1968) proved that a negative feedback model with two variables expressed by ordinary differential equations do not generate self-sustained oscillations. Kurosawa et al. (2002) expanded Griffith׳s result to the general type of negative feedback model with two variables. In this paper, we propose discrete and ultradiscrete feedback models with two variables that exhibit self-sustained oscillations. To obtain the model, we applied tropical discretization and ultradiscretization to a continuous model with two variables and then investigated its bifurcation structures and the conditions of parameters for oscillations. We found that when the degradation rate of the variables is lower than their synthesis rate, the proposed models generate oscillations by Neimark-Sacker bifurcation. We further demonstrate that the ultradiscrete model can be reduced to a Boolean system under some conditions. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Comparative study of models of the recirculation loop with 10 jet pumps using different components in the code RELAP5/SCDAPSIM Mod.3.4

    International Nuclear Information System (INIS)

    Araiza M, E.; Ortiz V, J.

    2012-10-01

    This work presents two arrangements in the nodal analysis of a recirculation loop for a BWR. Each one of these arrangements includes the ten jet pumps in each loop, instead of the traditional arrangement that consist of only jet pump representing to the ten pumps of a loop. The difference among the two models is presented mainly in the nodal analysis of the connection type cross-reduction, which takes charge of distributing the coolant flow to the lateral head stocks, where the vertical pipes (risers) that send the flow toward the jet pumps are connected. In the first arrangement the cross-reduction is modeled using the Branch component that is used in the interconnections simulation of hydrodynamic components. In the second arrangement the cross is simulated connecting the two distributor lateral head stocks with the main pipe of the loop by means of two simple unions that are modeled with the component SNGLJUN. The obtained results of the execution of both models are compared, taking important variables as reference, like pressures and mass expenses for the same components of both models. Finally these results are compared with the proportionate results by the traditional model. (Author)

  8. Investigation, modelling and control of the 1.9 K cooling loop for superconducting magnets for the Large Hadron Collider

    CERN Document Server

    Flemsæter, Bjorn

    2000-01-01

    The temperature of the superconducting magnets for the 27 km LHC particle accelerator under construction at CERN is a control parameter with strict operating constraints imposed by (a) the maximum temperature at which the magnets can operate, (b) the cooling capacity of the cryogenic system, (c) the variability of applied heat loads and (d) the accuracy of the instrumentation. A pilot plant for studying aspects beyond single magnet testing has been constructed. This magnet test string is a 35-m full-scale model if the LHC and consists of four superconducting cryogmagnets operating in a static bath of He II at 1.9 K. An experimental investigation of the properties dynamic characteristics of the 1.9 K cooling loop of the magnet test string has been carried out. A first principle model of the system has been created. A series of experiments designed for system identification purposes have been carried out, and black box models of the system have been created on the basis on the recorded data. A Model Predictive ...

  9. A Multiscale Closed-Loop Cardiovascular Model, with Applications to Heart Pacing and Hemorrhage

    Science.gov (United States)

    Canuto, Daniel; Eldredge, Jeff; Chong, Kwitae; Benharash, Peyman; Dutson, Erik

    2017-11-01

    A computational tool is developed for simulating the dynamic response of the human cardiovascular system to various stressors and injuries. The tool couples zero-dimensional models of the heart, pulmonary vasculature, and peripheral vasculature to one-dimensional models of the major systemic arteries. To simulate autonomic response, this multiscale circulatory model is integrated with a feedback model of the baroreflex, allowing control of heart rate, cardiac contractility, and peripheral impedance. The performance of the tool is demonstrated in two scenarios: increasing heart rate by stimulating the sympathetic nervous system, and an acute 10 percent hemorrhage from the left femoral artery.

  10. Use of intraperitoneal xenon-133 for imaging of intestinal strangulation in small bowel obstruction. [Rats; Dogs

    Energy Technology Data Exchange (ETDEWEB)

    Bulkley, G.B.; Gharagozloo, F.; Alderson, P.O.; Horn, S.D.; Zuidema, G.D.

    1981-01-01

    Intraperitoneal xenon-133 dissolved in saline solution was evaluated for the detection of early strangulation in a reproducible model of segmental intestinal obstruction in rats and dogs. There was a highly significant delay inexternally detected isotope washout from animals with strangulated loops compared with normal, sham operated and simple (nonstrangulated) obstruction control groups. Corresponding anterior abdominal gamma camera images showed marked retention of isotope at 1 hour in the strangulation obstruction groups and the sites of this activity corresponsed to the location of the ischemic loops. Blinded readings of these images by nuclear radiologists showed this method to be highly accurate for the detection of strangulation in these animal models. This method should be directly applicable to patients with intestinal obstruction.

  11. Use of intraperitoneal xenon-133 for imaging of intestinal strangulation in small bowel obstruction

    International Nuclear Information System (INIS)

    Bulkley, G.B.; Gharagozloo, F.; Alderson, P.O.; Horn, S.D.; Zuidema, G.D.

    1981-01-01

    Intraperitoneal xenon-133 dissolved in saline solution was evaluated for the detection of early strangulation in a reproducible model of segmental intestinal obstruction in rats and dogs. There was a highly significant delay inexternally detected isotope washout from animals with strangulated loops compared with normal, sham operated and simple (nonstrangulated) obstruction control groups. Corresponding anterior abdominal gamma camera images showed marked retention of isotope at 1 hour in the strangulation obstruction groups and the sites of this activity corresponsed to the location of the ischemic loops. Blinded readings of these images by nuclear radiologists showed this method to be highly accurate for the detection of strangulation in these animal models. This method should be directly applicable to patients with intestinal obstruction

  12. Intestinal circulation during inhalation anesthesia

    International Nuclear Information System (INIS)

    Tverskoy, M.; Gelman, S.; Fowler, K.C.; Bradley, E.L.

    1985-01-01

    This study was designed to evaluate the influence of inhalational agents on the intestinal circulation in an isolated loop preparation. Sixty dogs were studied, using three intestinal segments from each dog. Selected intestinal segments were pumped with aortic blood at a constant pressure of 100 mmHg. A mixture of 86 Rb and 9-microns spheres labeled with 141 Ce was injected into the arterial cannula supplying the intestinal loop, while mesenteric venous blood was collected for activity counting. A very strong and significant correlation was found between rubidium clearance and microsphere entrapment (r = 0.97, P less than 0.0001). Nitrous oxide anesthesia was accompanied by a higher vascular resistance (VR), lower flow (F), rubidium clearance (Cl-Rb), and microspheres entrapment (Cl-Sph) than pentobarbital anesthesia, indicating that the vascular bed in the intestinal segment was constricted and flow (total and nutritive) decreased. Halothane, enflurane, and isoflurane anesthesia were accompanied by a much lower arteriovenous oxygen content difference (AVDO 2 ) and oxygen uptake than pentobarbital or nitrous oxide. Compared with pentobarbital, enflurane anesthesia was not accompanied by marked differences in VR, F, Cl-Rb, and Cl-Sph; halothane at 2 MAC decreased VR and increased F and Cl-Rb while isoflurane increased VR and decreased F. alpha-Adrenoceptor blockade with phentolamine (1 mg . kg-1) abolished isoflurane-induced vasoconstriction, suggesting that the increase in VR was mediated via circulating catecholamines

  13. Isotopic identification of intestinal strangulation

    International Nuclear Information System (INIS)

    Anderson, M.C.; Selby, J.B.

    1982-01-01

    A small series of eleven dogs prepared with a strangulating segment of jejunum demonstrated that a radionuclide, 99 mTc-labelled albumin, concentrates in the lumen and bowel wall of the affected intestinal segment. Modern scanning equipment accurately localized the strangulating loop. This technique has the potential of identifying patients with intestinal obstruction, in whom strangulation is a factor, prior to the development of impaired arterial inflow and frank gangrene. These findings confirmed earlier obstructions that were reported when nuclear scanning instrumentation was less sophisticated. Identification of patients at risk for intestinal strangulation requires a high index of suspicion. Excruciating cramping abdominal pain out of proportion to physical findings, roentgenogram evidence, and laboratory studies should alert the physician to the possibility of intestinal ischemia and closed loop obstruction. Radionuclide scanning in such cases may be of assistance in defining or excluding the diagnosis of a strangulating mechanism. The test is simple, relatively economical, and represents a low risk procedure to patients. It would have no place when the classic physical and laboratory findings of intestinal infarction are present

  14. Isotopic identification of intestinal strangulation

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, M.C.; Selby, J.B.

    1982-12-01

    A small series of eleven dogs prepared with a strangulating segment of jejunum demonstrated that a radionuclide, /sup 99/mTc-labelled albumin, concentrates in the lumen and bowel wall of the affected intestinal segment. Modern scanning equipment accurately localized the strangulating loop. This technique has the potential of identifying patients with intestinal obstruction, in whom strangulation is a factor, prior to the development of impaired arterial inflow and frank gangrene. These findings confirmed earlier obstructions that were reported when nuclear scanning instrumentation was less sophisticated. Identification of patients at risk for intestinal strangulation requires a high index of suspicion. Excruciating cramping abdominal pain out of proportion to physical findings, roentgenogram evidence, and laboratory studies should alert the physician to the possibility of intestinal ischemia and closed loop obstruction. Radionuclide scanning in such cases may be of assistance in defining or excluding the diagnosis of a strangulating mechanism. The test is simple, relatively economical, and represents a low risk procedure to patients. It would have no place when the classic physical and laboratory findings of intestinal infarction are present.

  15. Intestine transplantation

    Directory of Open Access Journals (Sweden)

    Tadeja Pintar

    2011-02-01

    Conclusion: Intestine transplantation is reserved for patients with irreversible intestinal failure due to short gut syndrome requiring total paranteral nutrition with no possibility of discontinuation and loss of venous access for patient maintenance. In these patients complications of underlying disease and long-term total parenteral nutrition are present.

  16. Laminated Intestinal Calculi – A Rare Complication of Crohn's Disease

    Directory of Open Access Journals (Sweden)

    Hugh J Freeman

    1995-01-01

    Full Text Available A 59-year-old male with a 36-year history of Crohn's disease and repeated resections for small intestinal strictures developed anemia and symptoms of an intermittent partial bowel obstruction. Barium studies showed recurrent small intestinal strictures as well as filling defects in a dilated loop proximal to a stenosed segment. Subsequent abdominal films and a computed tomographic study suggested laminated radiopaque calculi with peripheral calcification in the dilated small intestinal loop. Resection of the strictured segment confirmed the presence of intestinal enterolithiasis.

  17. Getting the Client Into the Loop in Information Systems Modelling Courses

    NARCIS (Netherlands)

    Sikkel, Nicolaas; Daneva, Maia

    2011-01-01

    Information system modelling is more than a translation of requirements from one notation into another, it is part of the requirements analysis process. Adding explicitness and making design choices should provide critical feedback to the requirements document being modelled. We want our students to

  18. An Integrated Loop Model of Corrective Feedback and Oral English Learning: A Case of International Students in the United States

    Science.gov (United States)

    Lee, Eun Jeong

    2017-01-01

    The author in this study introduces an integrated corrective feedback (CF) loop to schematize the interplay between CF and independent practice in L2 oral English learning among advanced-level adult ESL students. The CF loop integrates insights from the Interaction, Output, and Noticing Hypotheses to show how CF can help or harm L2 learners'…

  19. A Step Forward to Closing the Loop between Static and Dynamic Reservoir Modeling

    Directory of Open Access Journals (Sweden)

    Cancelliere M.

    2014-12-01

    Full Text Available The current trend for history matching is to find multiple calibrated models instead of a single set of model parameters that match the historical data. The advantage of several current workflows involving assisted history matching techniques, particularly those based on heuristic optimizers or direct search, is that they lead to a number of calibrated models that partially address the problem of the non-uniqueness of the solutions. The importance of achieving multiple solutions is that calibrated models can be used for a true quantification of the uncertainty affecting the production forecasts, which represent the basis for technical and economic risk analysis. In this paper, the importance of incorporating the geological uncertainties in a reservoir study is demonstrated. A workflow, which includes the analysis of the uncertainty associated with the facies distribution for a fluvial depositional environment in the calibration of the numerical dynamic models and, consequently, in the production forecast, is presented. The first step in the workflow was to generate a set of facies realizations starting from different conceptual models. After facies modeling, the petrophysical properties were assigned to the simulation domains. Then, each facies realization was calibrated separately by varying permeability and porosity fields. Data assimilation techniques were used to calibrate the models in a reasonable span of time. Results showed that even the adoption of a conceptual model for facies distribution clearly representative of the reservoir internal geometry might not guarantee reliable results in terms of production forecast. Furthermore, results also showed that realizations which seem fully acceptable after calibration were not representative of the true reservoir internal configuration and provided wrong production forecasts; conversely, realizations which did not show a good fit of the production data could reliably predict the reservoir

  20. Distinct intestinal adaptation for vitamin B12 and bile acid absorption revealed in a new mouse model of massive ileocecal resection.

    Science.gov (United States)

    Matsumoto, Yuka; Mochizuki, Wakana; Akiyama, Shintaro; Matsumoto, Taichi; Nozaki, Kengo; Watanabe, Mamoru; Nakamura, Tetsuya

    2017-09-15

    Ileocecal resection (ICR), one of several types of intestinal resection that results in short bowel syndrome (SBS), causes severe clinical disease in humans. We here describe a mouse model of massive ICR in which 75% of the distal small intestine is removed. We demonstrate that mice underwent 75% ICR show severe clinical signs and high mortality, which may recapitulate severe forms of human SBS, despite an adaptive response throughout the remnant intestine. By using this model, we also investigated whether the epithelium of the remnant intestine shows enhanced expression of factors involved in region-specific functions of the ileum. Cubn mRNA and its protein product, which play an essential role in vitamin B12 absorption in the ileum, are not compensatory up-regulated in any part of the remnant intestine, demonstrating a clear contrast with post-operative up-regulation of genes involved in bile acid absorption. Our study suggests that functional adaptation by phenotypical changes in the intestinal epithelium is not a general feature for nutrient absorption systems that are confined to the ileum. We also propose that the mouse model developed in this study will become a unique system to facilitate studies on SBS with ICR in humans. © 2017. Published by The Company of Biologists Ltd.

  1. [Improvement of intestinal absorption of poorly absorbable drugs by various sugar esters].

    Science.gov (United States)

    Yamamoto, Akira; Katsumi, Hidemasa; Kusamori, Kosuke; Sakane, Toshiyasu

    2014-01-01

    Effects of sucrose fatty acid esters (sugar esters) on the intestinal absorption of poorly absorbable drugs were examined by an in situ closed loop method in rats. 5(6)-Carboxyfluorescein (CF) and fluorescein isothiocyanate-dextrans (FDs) with various molecular weights were used as model drugs of poorly absorbable drugs. The absorption of CF from the rat small intestine was significantly enhanced in the presence of various sugar esters and a maximal absorption enhancing effect was observed in the presence of 0.5%(w/v) S-1670. The absorption enhancing effect of S-1670 in the small intestine decreased as the molecular weights of drugs increased. Moreover, we evaluated the intestinal membrane damage with or without various sugar esters. These sugar esters (0.5%(w/v)) did not increase the activities of lactate dehydrogenase (LDH), suggesting that these sugar esters did not cause serious membrane damage to the intestinal epithelium. Furthermore, these sugar esters increased membrane fluidity of lipid layers of the intestinal brush border membranes and decreased the transepithelial electrical resistance (TEER) of Caco-2 cells. Therefore, these findings suggested that these sugar esters might improve the intestinal absorption of poorly absorbable drugs via a transcellular and a paracellular pathways.

  2. Mathematical Modeling of the Pituitary-Thyroid Feedback Loop: Role of a TSH-T3-Shunt and Sensitivity Analysis.

    Science.gov (United States)

    Berberich, Julian; Dietrich, Johannes W; Hoermann, Rudolf; Müller, Matthias A

    2018-01-01

    Despite significant progress in assay technology, diagnosis of functional thyroid disorders may still be a challenge, as illustrated by the vague upper limit of the reference range for serum thyrotropin ( TSH ). Diagnostical problems also apply to subjects affected by syndrome T, i.e., those 10% of hypothyroid patients who continue to suffer from poor quality of life despite normal TSH concentrations under substitution therapy with levothyroxine ( L - T 4 ). In this paper, we extend a mathematical model of the pituitary-thyroid feedback loop in order to improve the understanding of thyroid hormone homeostasis. In particular, we incorporate a TSH - T 3 -shunt inside the thyroid, whose existence has recently been demonstrated in several clinical studies. The resulting extended model shows good accordance with various clinical observations, such as a circadian rhythm in free peripheral triiodothyronine ( FT 3 ). Furthermore, we perform a sensitivity analysis of the derived model, revealing the dependence of TSH and hormone concentrations on different system parameters. The results have implications for clinical interpretation of thyroid tests, e.g., in the differential diagnosis of subclinical hypothyroidism.

  3. Closed-Loop Supply Chain Planning Model for a Photovoltaic System Manufacturer with Internal and External Recycling

    Directory of Open Access Journals (Sweden)

    Songi Kim

    2016-06-01

    Full Text Available The photovoltaic (PV generation system has been widely used since the late 1990s. Considering its lifespan of 20 to 30 years, many end-of-life systems will emerge in the near future. This is why recycling PV systems will be beneficial (and may even be detrimental to both the environment and the economy. Through the recycling process, hazardous by-product substances such as cadmium and lead can be treated properly. Moreover, valuable materials including indium, gallium, and tellurium can be extracted and reused for manufacturing purposes. Even though many studies have dealt with issues related to the PV system and its recycling policy, they lack significant factors regarding the recycling policy. This study analyzes and compares three real cases of manufacturer’s recycling policy, including Deutsche Solar, First Solar, and PV Cycle, from the perspective of a closed-loop supply chain. Two mathematical models are developed to help PV system manufacturers establish supply chain planning and choose suitable recycling policies in consideration of different circumstances. Furthermore, an experimental example of these models will be used to validate and conclude the significance of the models. The results from this study will show that recycling CdTe PV systems is much more efficient than recycling c-Si PV systems and that, in the case of c-Si, it is better to outsource recycling end-of-life systems and dispose of all manufacturing scrap.

  4. Development of a model for the thermal-hydraulic characterization of the He-FUS3 loop

    Energy Technology Data Exchange (ETDEWEB)

    Barone, G., E-mail: gianluca.barone@for.unipi.it [University of Pisa, Department of Civil and Industrial Engineering (DICI), Pisa (Italy); Coscarelli, E.; Forgione, N.; Martelli, D. [University of Pisa, Department of Civil and Industrial Engineering (DICI), Pisa (Italy); Del Nevo, A.; Tarantino, M.; Utili, M. [ENEA UTIS-TCI, CR Brasimone, Camugnano (Italy); Ricapito, I.; Calderoni, P. [TBM& MD Project, Fusion for Energy, EU Commission, Carrer J. Pla, 2, Building B3, 08019 Barcelona (Spain)

    2015-10-15

    Highlights: • RELAP5-3D model of He-FUS3 facility and turbo circulator (TC). • Cold and hot facility T/H numerical analysis for the TC operanting range. • Effect of the cold by-pass opening on the facility performances. - Abstract: He-FUS3 is a helium facility designed and realized by ENEA in order to test the thermal-mechanical properties of prototypical breeding blanket module assemblies of a DEMO reactor. The actual facility has been upgraded with a high performance turbo circulator and a water heat exchanger integrating the pre-existent air cooler. In addition, a new test section located in the loop hot zone has been settled down with the objective of investigating safety relevant transient conditions of “In-TBM” LOCA scenarios. A RELAP5-3D{sup ©} model has been developed to perform a set of preliminary simulations on the new He-FUS3 layout. Both cold and hot stationary conditions have been analyzed evaluating the turbo circulator performances for a wide range of helium flow rate. Outcomes have shown that RELAP5-3D{sup ©} is an effective tool in reproducing the most significant phenomena of He-FUS3 system, providing relevant insight supporting future experimental campaigns. The post-test analysis phase will be, of course, fundamental for the qualification of a consistent numerical model.

  5. Respiratory system model for quasistatic pulmonary pressure-volume (P-V) curve: inflation-deflation loop analyses.

    Science.gov (United States)

    Amini, R; Narusawa, U

    2008-06-01

    A respiratory system model (RSM) is developed for the deflation process of a quasistatic pressure-volume (P-V) curve, following the model for the inflation process reported earlier. In the RSM of both the inflation and the deflation limb, a respiratory system consists of a large population of basic alveolar elements, each consisting of a piston-spring-cylinder subsystem. A normal distribution of the basic elements is derived from Boltzmann statistical model with the alveolar closing (opening) pressure as the distribution parameter for the deflation (inflation) process. An error minimization by the method of least squares applied to existing P-V loop data from two different data sources confirms that a simultaneous inflation-deflation analysis is required for an accurate determination of RSM parameters. Commonly used terms such as lower inflection point, upper inflection point, and compliance are examined based on the P-V equations, on the distribution function, as well as on the geometric and physical properties of the basic alveolar element.

  6. Resolution of an uncertain closed-loop logistics model: an application to fuzzy linear programs with risk analysis.

    Science.gov (United States)

    Wang, Hsiao-Fan; Hsu, Hsin-Wei

    2010-11-01

    With the urgency of global warming, green supply chain management, logistics in particular, has drawn the attention of researchers. Although there are closed-loop green logistics models in the literature, most of them do not consider the uncertain environment in general terms. In this study, a generalized model is proposed where the uncertainty is expressed by fuzzy numbers. An interval programming model is proposed by the defined means and mean square imprecision index obtained from the integrated information of all the level cuts of fuzzy numbers. The resolution for interval programming is based on the decision maker (DM)'s preference. The resulting solution provides useful information on the expected solutions under a confidence level containing a degree of risk. The results suggest that the more optimistic the DM is, the better is the resulting solution. However, a higher risk of violation of the resource constraints is also present. By defining this probable risk, a solution procedure was developed with numerical illustrations. This provides a DM trade-off mechanism between logistic cost and the risk. Copyright 2010 Elsevier Ltd. All rights reserved.

  7. A review of spatial computational models for multi-cellular systems, with regard to intestinal crypts and colorectal cancer development.

    Science.gov (United States)

    De Matteis, Giovanni; Graudenzi, Alex; Antoniotti, Marco

    2013-06-01

    Colon rectal cancers (CRC) are the result of sequences of mutations which lead the intestinal tissue to develop in a carcinoma following a "progression" of observable phenotypes. The actual modeling and simulation of the key biological structures involved in this process is of interest to biologists and physicians and, at the same time, it poses significant challenges from the mathematics and computer science viewpoints. In this report we give an overview of some mathematical models for cell sorting (a basic phenomenon that underlies several dynamical processes in an organism), intestinal crypt dynamics and related problems and open questions. In particular, major attention is devoted to the survey of so-called in-lattice (or grid) models and off-lattice (off-grid) models. The current work is the groundwork for future research on semi-automated hypotheses formation and testing about the behavior of the various actors taking part in the adenoma-carcinoma progression, from regulatory processes to cell-cell signaling pathways.

  8. FETAL METABOLIC PROGRAMMING OF THE SMALL INTESTINE IN A COPENHAGEN SHEEP MODEL

    DEFF Research Database (Denmark)

    Axel, Anne Marie Dixen; Khanal, Prabhat; Kongsted, Anna Hauntoft

    Fetal metabolic programming states that early life nutrition is implicated with the risk of later disease development and both under- and overnutrition during gestation might predispose individuals to develop obesity or diabetes later in life. Obesity operations called “gastric bypass” operations...... have shown unexpected involvement of the small intestine in diabetes pathophysiology as it in most cases result in a complete resolution of the diabetes before weight loss. Therefore we hypothesize that the small intestine is a subject of metabolic programming and that this programming can predispose...... for diabetes development. Twin-pregnant ewes where fed a Normal, a Low or a High diet during the last 6 weeks of gestation and the twin lambs where fed either a Conventional or a High fat, High carbohydrate (HCHF) diet during the first 6 months of life. Feeding challenge tests were performed on all lambs...

  9. A regulated multiscale closed-loop cardiovascular model, with applications to hemorrhage and hypertension.

    Science.gov (United States)

    Canuto, Daniel; Chong, Kwitae; Bowles, Cayley; Dutson, Erik P; Eldredge, Jeff D; Benharash, Peyman

    2018-03-02

    A computational tool is developed for simulating the dynamic response of the human cardiovascular system to various stressors and injuries. The tool couples zero-dimensional models of the heart, pulmonary vasculature, and peripheral vasculature to one-dimensional models of the major systemic arteries. To simulate autonomic response, this multiscale circulatory model is integrated with a feedback model of the baroreflex, allowing control of heart rate, cardiac contractility, and peripheral impedance. The performance of the tool is demonstrated in two scenarios: neurogenic hypertension by sustained stimulation of the sympathetic nervous system, and an acute 10 percent hemorrhage from the left femoral artery. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  10. Closed-loop model: An optimization of integrated thin-film magnetic devices

    Energy Technology Data Exchange (ETDEWEB)

    El-Ghazaly, Amal, E-mail: amale@stanford.edu [Electrical Engineering, Stanford University, Stanford, CA 94305 (United States); Sato, Noriyuki [Electrical Engineering, Stanford University, Stanford, CA 94305 (United States); White, Robert M. [Materials Science and Engineering, Stanford University, Stanford, CA 94305 (United States); Wang, Shan X. [Electrical Engineering, Stanford University, Stanford, CA 94305 (United States); Materials Science and Engineering, Stanford University, Stanford, CA 94305 (United States)

    2017-06-15

    Highlights: • An analytical model for inductance of thin-film magnetic devices was developed. • Different device topologies and magnetic permeabilities were addressed. • Inductance of various topologies were calculated and compared with simulation. • The model predicts simulated values with excellent accuracy. - Abstract: A generic analytical model has been developed to fully describe the flux closure through magnetic inductors. The model was applied to multiple device topologies including solenoidal single return path and dual return path inductors as well as spiral magnetic inductors for a variety of permeabilities and dimensions. The calculated inductance values from the analytical model were compared with simulated results for each of the analyzed device topologies and found to agree within 0.1 nH for the range of typical thin-film magnetic permeabilities (∼10{sup 2} to 10{sup 3}). Furthermore, the model can be used to evaluate behavior in other integrated or discrete magnetic devices with either non-isotropic or isotropic permeability and used to produce more efficient device designs in the future.

  11. Closed-loop model: An optimization of integrated thin-film magnetic devices

    International Nuclear Information System (INIS)

    El-Ghazaly, Amal; Sato, Noriyuki; White, Robert M.; Wang, Shan X.

    2017-01-01

    Highlights: • An analytical model for inductance of thin-film magnetic devices was developed. • Different device topologies and magnetic permeabilities were addressed. • Inductance of various topologies were calculated and compared with simulation. • The model predicts simulated values with excellent accuracy. - Abstract: A generic analytical model has been developed to fully describe the flux closure through magnetic inductors. The model was applied to multiple device topologies including solenoidal single return path and dual return path inductors as well as spiral magnetic inductors for a variety of permeabilities and dimensions. The calculated inductance values from the analytical model were compared with simulated results for each of the analyzed device topologies and found to agree within 0.1 nH for the range of typical thin-film magnetic permeabilities (∼10 2 to 10 3 ). Furthermore, the model can be used to evaluate behavior in other integrated or discrete magnetic devices with either non-isotropic or isotropic permeability and used to produce more efficient device designs in the future.

  12. Top quark rare decays via loop-induced FCNC interactions in extended mirror fermion model

    Science.gov (United States)

    Hung, P. Q.; Lin, Yu-Xiang; Nugroho, Chrisna Setyo; Yuan, Tzu-Chiang

    2018-02-01

    Flavor changing neutral current (FCNC) interactions for a top quark t decays into Xq with X represents a neutral gauge or Higgs boson, and q a up- or charm-quark are highly suppressed in the Standard Model (SM) due to the Glashow-Iliopoulos-Miami mechanism. Whilst current limits on the branching ratios of these processes have been established at the order of 10-4 from the Large Hadron Collider experiments, SM predictions are at least nine orders of magnitude below. In this work, we study some of these FCNC processes in the context of an extended mirror fermion model, originally proposed to implement the electroweak scale seesaw mechanism for non-sterile right-handed neutrinos. We show that one can probe the process t → Zc for a wide range of parameter space with branching ratios varying from 10-6 to 10-8, comparable with various new physics models including the general two Higgs doublet model with or without flavor violations at tree level, minimal supersymmetric standard model with or without R-parity, and extra dimension model.

  13. Ex vivo culture of intestinal crypt organoids as a model system for assessing cell death induction in intestinal epithelial cells and enteropathy

    NARCIS (Netherlands)

    Grabinger, T.; Luks, L.; Kostadinova, F.; Zimberlin, C.; Medema, J. P.; Leist, M.; Brunner, T.

    2014-01-01

    Intestinal epithelial cells (IECs) not only have a critical function in the absorption of nutrients, but also act as a physical barrier between our body and the outside world. Damage and death of the epithelial cells lead to the breakdown of this barrier function and inflammation due to access of

  14. Intestinal adaptation is stimulated by partial enteral nutrition supplemented with the prebiotic short-chain fructooligosaccharide in a neonatal intestinal failure piglet model

    DEFF Research Database (Denmark)

    Barnes, Jennifer L; Hartmann, Bolette; Holst, Jens Juul

    2012-01-01

    Butyrate has been shown to stimulate intestinal adaptation when added to parenteral nutrition (PN) following small bowel resection but is not available in current PN formulations. The authors hypothesized that pre- and probiotic administration may be a clinically feasible method to administer...

  15. Preoperative irradiation with 5x5 Gy in a murine isolated colon loop model does not cause anastomotic weakening after colon resection

    NARCIS (Netherlands)

    Karliczek, A.; Zeebregts, C. J.; Benaron, D. A.; Coppes, R. P.; Wiggers, T.; van Dam, G. M.

    2008-01-01

    Introduction There are conflicting studies on the influence of fractionated preoperative 5 days of 5 Gy irradiation on tissue oxygenation and subsequent colonic anastomotic strength. To elucidate the effect of preoperative irradiation on anastomotic strength, an isolated colon loop model was

  16. Development and application of a low volume, increased throughput in vitro model simulating the passage through small intestine

    DEFF Research Database (Denmark)

    Cieplak, Tomasz Maciej

    The gastrointestinal tract (GIT) is an organ system responsible for food digestion, absorption of nutrients and the expelling of waste. Due to a high demand for testing the intestinal faith of pharmaceutical and bioactive food formulations, there is great interest from food, bioscience...... in vitro model of the small intestine (duodenum, jejunum, ileum) as a screening platform for the study of food digestibility, intestinal survival of probiotics and absorption of drugs and small nutrients. The GIT harbours a vast number of microorganisms called the gut microbiota. These bacteria...... are unevenly distributed along the GIT, ranging from 101-103 cells/g in the stomach, through 103-108 cells/g in the small intestine and up to 1012 cells/g in the colon. In the last decade, numerous studies have been conducted focussing on the faecal microbiota composition and its impact on the host health...

  17. Signal model of noise in open-loop fiber-optic gyros.

    Science.gov (United States)

    He, K; Ye, W; He, Z

    1997-12-01

    The characteristics of noise in fiber-optic gyros are analyzed quantitatively. Based on its physical characteristics and on autocorrelation function evidence, the noise is modeled as the addition of fractal Brownian motion (FBM) and Gaussian white noise (GWN). The value of self-similarlity parameter H in FBM and the intensity of GWN, sigma(w), in the model are robustly determined with an algorithm based on an orthonormal wavelet transform, which demonstrates well the coexistence of the long- and short-term correlation components of the gyro noise. Moreover, it is revealed that FBM dominates the gyro noise, whereas the GWN is minor.

  18. Inhibition of p38 mitogen-activated protein kinase attenuates butyrate-induced intestinal barrier impairment in a Caco-2 cell monolayer model.

    Science.gov (United States)

    Huang, Xiao-Zhong; Li, Zhong-Rong; Zhu, Li-Bin; Huang, Hui-Ya; Hou, Long-Long; Lin, Jing

    2014-08-01

    Butyrate is well known to induce apoptosis in differentiating intestinal epithelial cells. The present study was designed to examine the role of p38 mitogen-activated protein kinase (MAPK) in butyrate-induced intestinal barrier impairment. The intestinal barrier was determined by measuring the transepithelial electrical resistance (TER) in a Caco-2 cell monolayer model. The permeability was determined by measuring transepithelial passage of fluorescein isothiocyanate-conjugated inulin (inulin-FITC). The morphology of the monolayers was examined with scanning electron microscopy. The apoptosis status was determined by annexin V-FITC labeling and flow cytometry. The activity of p38 MAPK was determined by the phosphorylation status of p38 with Western blotting. Butyrate at 5 mM increases the apoptosis rate of Caco-2 cells and induces impairment of intestinal barrier functions as determined by decreased TER and increased inulin-FITC permeability. Butyrate treatment activates p38 MAPK in a concentration- and time-dependent manner. SB203580, a specific p38 inhibitor, inhibits butyrate-induced Caco-2 cell apoptosis. Treatment of SB203580 significantly attenuates the butyrate-induced impairment of barrier functions in the Caco-2 cell monolayer model. p38 MAPK can be activated by butyrate and is involved in the butyrate-induced apoptosis and impairment of intestinal barrier function. Inhibition of p38 MAPK can significantly attenuate butyrate-induced intestinal barrier dysfunction.

  19. Metabolism of sinigrin (2-propenyl glucosinolate) by the human colonic microflora in a dynamic in vitro large-intestinal model.

    Science.gov (United States)

    Krul, Cyrille; Humblot, Christèle; Philippe, Catherine; Vermeulen, Martijn; van Nuenen, Marleen; Havenaar, Robert; Rabot, Sylvie

    2002-06-01

    Cruciferous vegetables, such as Brassica, which contain substantial quantities of glucosinolates, have been suggested to possess anticarcinogenic activity. Cutting and chewing of cruciferous vegetables releases the thioglucosidase enzyme myrosinase, which degrades glucosinolates to isothiocyanates and other minor metabolites. Cooking of cruciferous vegetables inactivates the myrosinase enzyme, allowing intact glucosinolates to reach the large intestine, where they can be degraded by the indigenous microflora into isothiocyanates. This local release of isothiocyanates may explain the protective effect of cruciferous vegetables on the colon epithelium. However, little is known about the amounts and identities of glucosinolate metabolites produced by the human microflora. The production of allyl isothiocyanate from sinigrin was investigated in a dynamic in vitro large-intestinal model, after inoculation with a complex microflora of human origin. Sinigrin and allyl isothiocyanate concentrations were analysed in the lumen and dialysis fluid of the model. Peak levels of allyl isothiocyanate were observed between 9 and 12 h after the addition of sinigrin. The model was first set up with a pooled and cultured human microflora, in which 1 and 4% of, respectively, 1 and 15 mM sinigrin, was converted into AITC. However, the conversion rate was remarkably higher if different individual human microflora were used. Between 10% and 30% (mean 19%) of the sinigrin was converted into allyl isothiocyanate. The results of this study suggest that allyl isothiocyanate is converted further into other, yet unknown, metabolites.

  20. Nutrients and Energy Balance Analysis for a Conceptual Model of a Three Loops off Grid, Aquaponics

    Directory of Open Access Journals (Sweden)

    Uri Yogev

    2016-12-01

    Full Text Available Food security, specifically in water scarce regions, is an increasing local and global challenge. Finding new ways to increase agricultural production in a sustainable manner is required. The current study suggests a conceptual model to integrate established recirculating aquaculture practices into a near-zero discharge aquaponic system that efficiently utilizes water, excreted nutrients and organic matter for energy. The suggested model allows to significantly extend the planted area and recover energy in the form of biogas to operate the system off-grid. A mass balance model of nitrogen, carbon and energy was established and solved, based on data from the literature. Results demonstrate that a fish standing stock of about 700 kg would produce 3.4 tons of fish annually and enough nutrients to grow about 35 tons of tomatoes per year (chosen as a model plant and recover sufficient energy (70 kWh/day to run the system on biogas and use less water. If proven successful, this approach may play a major role in sustainably enhancing food security in rural and water scarce regions.

  1. Modelling and analysis of an open-loop induction motor drive ...

    Indian Academy of Sciences (India)

    in the inverter output and also certain change in the funda- mental voltage [1–4]. The change in fundamental voltage is important from the control perspective, and can be modelled as a drop across a fictitious “equivalent” resistance [5–8]. This paper presents an analytical expression for this dead- time equivalent resistance.

  2. Analysis, Modelling, and Simulation of Droop Control with Virtual Impedance Loop Applied to Parallel UPS Systems

    DEFF Research Database (Denmark)

    Lima, Francisco Kleber A.; Branco, Carlos Gustavo C.; Guerrero, Josep M.

    2013-01-01

    is difficult due to its physical location. This paper has considered that the UPS systems there were no comunication between their controls. A detailed mathematical model about the explored system is shown in that work and simulation results are presented in order to prove the theory presented....

  3. Numerical modelling of the dehydration of waste concrete fines : An attempt to close the recycling loop

    NARCIS (Netherlands)

    Teklay, Abraham; Vahidi, A.; Lotfi, Somayeh; Di Maio, F.; Rem, P.C.; Di Maio, F.; Lotfi, S.; Bakker, M.; Hu, M.; Vahidi, A.

    2017-01-01

    The ever-increasing interest on sustainable raw materials has urged the quest for recycled materials that can be used as a partial or total replacement of fine fractions in the production of concrete. This paper demonstrates a modelling study of recycled concrete waste fines and the possibility of

  4. Modelling and analysis of an open-loop induction motor drive ...

    Indian Academy of Sciences (India)

    for the same in terms of inverter dead-time, switching frequency, modulation index and load impedance. The notion of dead-time equivalent resistance is shown to simplify the solution of the non-linear steady-state model. The analytically evaluated steady-state solutions are validated through numerical simulations and ...

  5. Hardware-in-the-Loop Simulation of a Distribution System with Air Conditioners under Model Predictive Control: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Sparn, Bethany F [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Ruth, Mark F [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Krishnamurthy, Dheepak [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Pratt, Annabelle [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Lunacek, Monte S [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Jones, Wesley B [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Wu, Hongyu [Kansas State University; Mittal, Saurabh [Mitre Corporation; Marks, Jesse [University of Missouri

    2017-08-01

    Many have proposed that responsive load provided by distributed energy resources (DERs) and demand response (DR) are an option to provide flexibility to the grid and especially to distribution feeders. However, because responsive load involves a complex interplay between tariffs and DER and DR technologies, it is challenging to test and evaluate options without negatively impacting customers. This paper describes a hardware-in-the-loop (HIL) simulation system that has been developed to reduce the cost of evaluating the impact of advanced controllers (e.g., model predictive controllers) and technologies (e.g., responsive appliances). The HIL simulation system combines large-scale software simulation with a small set of representative building equipment hardware. It is used to perform HIL simulation of a distribution feeder and the loads on it under various tariff structures. In the reported HIL simulation, loads include many simulated air conditioners and one physical air conditioner. Independent model predictive controllers manage operations of all air conditioners under a time-of-use tariff. Results from this HIL simulation and a discussion of future development work of the system are presented.

  6. Automated service quality and its behavioural consequences in CRM Environment: A structural equation modeling and causal loop diagramming approach

    Directory of Open Access Journals (Sweden)

    Arup Kumar Baksi

    2012-08-01

    Full Text Available Information technology induced communications (ICTs have revolutionized the operational aspects of service sector and have triggered a perceptual shift in service quality as rapid dis-intermediation has changed the access-mode of services on part of the consumers. ICT-enabled services further stimulated the perception of automated service quality with renewed dimensions and there subsequent significance to influence the behavioural outcomes of the consumers. Customer Relationship Management (CRM has emerged as an offshoot to technological breakthrough as it ensured service-encapsulation by integrating people, process and technology. This paper attempts to explore the relationship between automated service quality and its behavioural consequences in a relatively novel business-philosophy – CRM. The study has been conducted on the largest public sector bank of India - State bank of India (SBI at Kolkata which has successfully completed its decade-long operational automation in the year 2008. The study used structural equation modeling (SEM to justify the proposed model construct and causal loop diagramming (CLD to depict the negative and positive linkages between the variables.

  7. Closed-loop dialog model of face-to-face communication with a photo-real virtual human

    Science.gov (United States)

    Kiss, Bernadette; Benedek, Balázs; Szijárto, Gábor; Takács, Barnabás

    2004-01-01

    We describe an advanced Human Computer Interaction (HCI) model that employs photo-realistic virtual humans to provide digital media users with information, learning services and entertainment in a highly personalized and adaptive manner. The system can be used as a computer interface or as a tool to deliver content to end-users. We model the interaction process between the user and the system as part of a closed loop dialog taking place between the participants. This dialog, exploits the most important characteristics of a face-to-face communication process, including the use of non-verbal gestures and meta communication signals to control the flow of information. Our solution is based on a Virtual Human Interface (VHI) technology that was specifically designed to be able to create emotional engagement between the virtual agent and the user, thus increasing the efficiency of learning and/or absorbing any information broadcasted through this device. The paper reviews the basic building blocks and technologies needed to create such a system and discusses its advantages over other existing methods.

  8. A Collection-Distribution Center Location and Allocation Optimization Model in Closed-Loop Supply Chain for Chinese Beer Industry

    Directory of Open Access Journals (Sweden)

    Kai Kang

    2017-01-01

    Full Text Available Recycling waste products is an environmental-friendly activity that can result in manufacturing cost saving and economic efficiency improving. In the beer industry, recycling bottles can reduce manufacturing cost and the industry’s carbon footprint. This paper presents a model for a collection-distribution center location and allocation problem in a closed-loop supply chain for the beer industry under a fuzzy random environment, in which the objectives are to minimize total costs and transportation pollution. Both random and fuzzy uncertainties, for which return rate and disposal rate are considered fuzzy random variables, are jointly handled in this paper to ensure a more practical problem solution. A heuristic algorithm based on priority-based global-local-neighbor particle swarm optimization (pb-glnPSO is applied to ensure reliable solutions for this NP-hard problem. A beer company case study is given to illustrate the application of the proposed model and to demonstrate the priority-based global-local-neighbor particle swarm optimization.

  9. A Multiple-Plasticity Spiking Neural Network Embedded in a Closed-Loop Control System to Model Cerebellar Pathologies.

    Science.gov (United States)

    Geminiani, Alice; Casellato, Claudia; Antonietti, Alberto; D'Angelo, Egidio; Pedrocchi, Alessandra

    2018-06-01

    The cerebellum plays a crucial role in sensorimotor control and cerebellar disorders compromise adaptation and learning of motor responses. However, the link between alterations at network level and cerebellar dysfunction is still unclear. In principle, this understanding would benefit of the development of an artificial system embedding the salient neuronal and plastic properties of the cerebellum and operating in closed-loop. To this aim, we have exploited a realistic spiking computational model of the cerebellum to analyze the network correlates of cerebellar impairment. The model was modified to reproduce three different damages of the cerebellar cortex: (i) a loss of the main output neurons (Purkinje Cells), (ii) a lesion to the main cerebellar afferents (Mossy Fibers), and (iii) a damage to a major mechanism of synaptic plasticity (Long Term Depression). The modified network models were challenged with an Eye-Blink Classical Conditioning test, a standard learning paradigm used to evaluate cerebellar impairment, in which the outcome was compared to reference results obtained in human or animal experiments. In all cases, the model reproduced the partial and delayed conditioning typical of the pathologies, indicating that an intact cerebellar cortex functionality is required to accelerate learning by transferring acquired information to the cerebellar nuclei. Interestingly, depending on the type of lesion, the redistribution of synaptic plasticity and response timing varied greatly generating specific adaptation patterns. Thus, not only the present work extends the generalization capabilities of the cerebellar spiking model to pathological cases, but also predicts how changes at the neuronal level are distributed across the network, making it usable to infer cerebellar circuit alterations occurring in cerebellar pathologies.

  10. An empirical approach for quantifying loop-mediated isothermal amplification (LAMP) using Escherichia coli as a model system.

    Science.gov (United States)

    Subramanian, Sowmya; Gomez, Romel D

    2014-01-01

    Loop mediated isothermal amplification (LAMP) is a highly efficient, selective and rapid DNA amplification technique for genetic screening of pathogens. However, despite its popularity, there is yet no mathematical model to quantify the outcome and no well-defined metric for comparing results that are available. LAMP is intrinsically complex and involves multiple pathways for gene replication, making fundamental modelling nearly intractable. To circumvent this difficulty, an alternate, empirical model is introduced that will allow one to extract a set of parameters from the concentration versus time curves. A simple recipe to deduce the time to positive, Tp--a parameter analogous to the threshold cycling time in polymerase chain reaction (PCR), is also provided. These parameters can be regarded as objective and unambiguous indicators of LAMP amplification. The model is exemplified on Escherichia coli strains by using the two gene fragments responsible for vero-toxin (VT) production and tested against VT-producing (O157 and O45) and non-VT producing (DH5 alpha) strains. Selective amplification of appropriate target sequences was made using well established LAMP primers and protocols, and the concentrations of the amplicons were measured using a Qubit 2.0 fluorometer at specific intervals of time. The data is fitted to a generalized logistic function. Apart from providing precise screening indicators, representing the data with a small set of numbers offers significant advantages. It facilitates comparisons of LAMP reactions independently of the sampling technique. It also eliminates subjectivity in interpretation, simplifies data analysis, and allows easy data archival, retrieval and statistical analysis for large sample populations. To our knowledge this work represents a first attempt to quantitatively model LAMP and offer a standard method that could pave the way towards high throughput automated screening.

  11. An empirical approach for quantifying loop-mediated isothermal amplification (LAMP using Escherichia coli as a model system.

    Directory of Open Access Journals (Sweden)

    Sowmya Subramanian

    Full Text Available Loop mediated isothermal amplification (LAMP is a highly efficient, selective and rapid DNA amplification technique for genetic screening of pathogens. However, despite its popularity, there is yet no mathematical model to quantify the outcome and no well-defined metric for comparing results that are available. LAMP is intrinsically complex and involves multiple pathways for gene replication, making fundamental modelling nearly intractable. To circumvent this difficulty, an alternate, empirical model is introduced that will allow one to extract a set of parameters from the concentration versus time curves. A simple recipe to deduce the time to positive, Tp--a parameter analogous to the threshold cycling time in polymerase chain reaction (PCR, is also provided. These parameters can be regarded as objective and unambiguous indicators of LAMP amplification. The model is exemplified on Escherichia coli strains by using the two gene fragments responsible for vero-toxin (VT production and tested against VT-producing (O157 and O45 and non-VT producing (DH5 alpha strains. Selective amplification of appropriate target sequences was made using well established LAMP primers and protocols, and the concentrations of the amplicons were measured using a Qubit 2.0 fluorometer at specific intervals of time. The data is fitted to a generalized logistic function. Apart from providing precise screening indicators, representing the data with a small set of numbers offers significant advantages. It facilitates comparisons of LAMP reactions independently of the sampling technique. It also eliminates subjectivity in interpretation, simplifies data analysis, and allows easy data archival, retrieval and statistical analysis for large sample populations. To our knowledge this work represents a first attempt to quantitatively model LAMP and offer a standard method that could pave the way towards high throughput automated screening.

  12. A prospective randomized controlled study of erythromycin on gastric and small intestinal distention: Implications for MR enterography

    Energy Technology Data Exchange (ETDEWEB)

    Bharucha, Adil E., E-mail: bharucha.adil@mayo.edu [Clinical Enteric Neuroscience Translational and Epidemiological Research (C.E.N.T.E.R.) Program, Division of Gastroenterology and Hepatology, College of Medicine, Mayo Clinic, 200 First St. S.W., Rochester, MN 55905 (United States); Fidler, Jeff L., E-mail: fidler.jeff@mayo.edu [Department of Radiology, College of Medicine, Mayo Clinic, 200 First St. S.W., Rochester, MN 55905 (United States); Huprich, James E., E-mail: huprich@mayo.edu [Department of Radiology, College of Medicine, Mayo Clinic, 200 First St. S.W., Rochester, MN 55905 (United States); Ratuapli, Shiva K., E-mail: ratuapli.shiva@mayo.edu [Clinical Enteric Neuroscience Translational and Epidemiological Research (C.E.N.T.E.R.) Program, Division of Gastroenterology and Hepatology, College of Medicine, Mayo Clinic, 200 First St. S.W., Rochester, MN 55905 (United States); Holmes, David R., E-mail: holmes.david3@mayo.edu [Biomedical Imaging Resource, College of Medicine, Mayo Clinic, 200 First St. S.W., Rochester, MN 55905 (United States); Riederer, Stephen J., E-mail: riederer@mayo.edu [MR Research Laboratory, College of Medicine, Mayo Clinic, 200 First St. S.W., Rochester, MN 55905 (United States); Zinsmeister, Alan R., E-mail: zinsmeis@mayo.edu [Division of Biomedical Statistics and Informatics, College of Medicine, Mayo Clinic, 200 First St. S.W., Rochester, MN 55905 (United States)

    2014-11-15

    Highlights: • Suboptimal small intestinal distention limits jejunal visualization during MRI. • In this controlled study, erythromycin increased gastric emptying measured with MRI. • However, effects on small intestinal dimensions were variable. - Abstract: Objectives: To assess if erythromycin increases gastric emptying and hence improves small intestinal distention during MR enterography. Methods: Gastric, small intestinal, and large intestinal volumes were assessed with MR after neutral oral contrast (1350 ml in 45 min) and balanced randomization to erythromycin (200 mg i.v., age 31 ± 3y, 13 females), or placebo (37 ± 3y, 13 females) in 40 healthy asymptomatic volunteers. Fat-suppressed T2-weighted MR images of the abdomen were acquired on a 1.5 T magnet at standard delay times for enterography. Gastric, small, and large intestinal volumes were measured by specialized software. In addition, two radiologists manually measured diameters and percentage distention of jejunal and ileal loops. Treatment effects were evaluated by an ITT analysis based on ANCOVA models. Results: All subjects tolerated erythromycin. MRI scans of the stomach and intestine were obtained at 62 ± 2 (mean ± SEM) and 74 ± 2 min respectively after starting oral contrast. Gastric volumes were lower (P < 0.0001) after erythromycin (260 ± 49 ml) than placebo (688 ± 63 ml) but jejunal, ileal, and colonic volumes were not significantly different. However, maximum (76–100%) jejunal distention was more frequently observed (P = 0.03) after erythromycin (8/20 subjects [40%]) than placebo (2/20 subjects [10%]). The diameter of a representative ileal loop was greater (P = 0.001) after erythromycin (18.8 ± 4.3 mm) than placebo (17.3 ± 2.8 mm) infusion. Conclusions: After ingestion of oral contrast, erythromycin accelerated gastric emptying but effects on small intestinal dimensions were variable. In balance, erythromycin did not substantially enhance small intestinal distention during

  13. A prospective randomized controlled study of erythromycin on gastric and small intestinal distention: Implications for MR enterography

    International Nuclear Information System (INIS)

    Bharucha, Adil E.; Fidler, Jeff L.; Huprich, James E.; Ratuapli, Shiva K.; Holmes, David R.; Riederer, Stephen J.; Zinsmeister, Alan R.

    2014-01-01

    Highlights: • Suboptimal small intestinal distention limits jejunal visualization during MRI. • In this controlled study, erythromycin increased gastric emptying measured with MRI. • However, effects on small intestinal dimensions were variable. - Abstract: Objectives: To assess if erythromycin increases gastric emptying and hence improves small intestinal distention during MR enterography. Methods: Gastric, small intestinal, and large intestinal volumes were assessed with MR after neutral oral contrast (1350 ml in 45 min) and balanced randomization to erythromycin (200 mg i.v., age 31 ± 3y, 13 females), or placebo (37 ± 3y, 13 females) in 40 healthy asymptomatic volunteers. Fat-suppressed T2-weighted MR images of the abdomen were acquired on a 1.5 T magnet at standard delay times for enterography. Gastric, small, and large intestinal volumes were measured by specialized software. In addition, two radiologists manually measured diameters and percentage distention of jejunal and ileal loops. Treatment effects were evaluated by an ITT analysis based on ANCOVA models. Results: All subjects tolerated erythromycin. MRI scans of the stomach and intestine were obtained at 62 ± 2 (mean ± SEM) and 74 ± 2 min respectively after starting oral contrast. Gastric volumes were lower (P < 0.0001) after erythromycin (260 ± 49 ml) than placebo (688 ± 63 ml) but jejunal, ileal, and colonic volumes were not significantly different. However, maximum (76–100%) jejunal distention was more frequently observed (P = 0.03) after erythromycin (8/20 subjects [40%]) than placebo (2/20 subjects [10%]). The diameter of a representative ileal loop was greater (P = 0.001) after erythromycin (18.8 ± 4.3 mm) than placebo (17.3 ± 2.8 mm) infusion. Conclusions: After ingestion of oral contrast, erythromycin accelerated gastric emptying but effects on small intestinal dimensions were variable. In balance, erythromycin did not substantially enhance small intestinal distention during

  14. Bacteria, bile salts, and intestinal monosaccharide malabsorption

    Science.gov (United States)

    Gracey, Michael; Burke, Valerie; Oshin, Ademola; Barker, Judith; Glasgow, Eric F.

    1971-01-01

    Intestinal monosaccharide transport was studied in a series of rats with a self-filling jejunal blind loop using 3mM arbutin (p-hydroxyphenyl-B-glucoside) or 1mM D-fructose as substrate in vitro and 10 mM arbutin or 5mM D-fructose in vivo. These results were compared with changes in the bacterial flora and state of conjugation of intraluminal bile salts in those animals. Observations were also made of the microscopic and ultrastructural appearances of the small-intestinal epithelium. In the small intestine of blind-loop rats intestinal monosaccharide transport is impaired, and in vitro is most marked in the blind loop, less so in the efferent jejunum, and not significantly altered in the afferent jejunum. A similar pattern of disturbed monosaccharide absorption was demonstrated by perfusions in vivo. The degree of the transport defect correlates closely with the luxuriance of the anaerobic flora, which averaged 108 per millilitre in the blind loop, 107 in the efferent jejunum, and 106 in the afferent jejunum. A similar pattern of abnormality of bile salt conjugation occurred. In the blind loop the ratio of free to conjugated bile salts was grossly abnormal; this disturbance was somewhat less marked in the efferent jejunum and considerably less in the intraluminal contents of the afferent jejunum. An irregularly distributed lesion, consisting of swelling and vacuolation of microvilli and intracellular organelles, was demonstrated in the small-intestinal epithelium of blind-loop animals. Impaired absorption of monosaccharides is a further consequence of bacterial contamination of the upper gut. It is suggested that this defect is caused by the presence of high levels of deconjugated bile salts produced by an abnormal anaerobic bacterial flora in the small intestine. ImagesFig. 3Fig. 4 PMID:4329096

  15. Linear Model-Based Predictive Control of the LHC 1.8 K Cryogenic Loop

    CERN Document Server

    Blanco-Viñuela, E; De Prada-Moraga, C

    1999-01-01

    The LHC accelerator will employ 1800 superconducting magnets (for guidance and focusing of the particle beams) in a pressurized superfluid helium bath at 1.9 K. This temperature is a severely constrained control parameter in order to avoid the transition from the superconducting to the normal state. Cryogenic processes are difficult to regulate due to their highly non-linear physical parameters (heat capacity, thermal conductance, etc.) and undesirable peculiarities like non self-regulating process, inverse response and variable dead time. To reduce the requirements on either temperature sensor or cryogenic system performance, various control strategies have been investigated on a reduced-scale LHC prototype built at CERN (String Test). Model Based Predictive Control (MBPC) is a regulation algorithm based on the explicit use of a process model to forecast the plant output over a certain prediction horizon. This predicted controlled variable is used in an on-line optimization procedure that minimizes an approp...

  16. Model-based rational feedback controller design for closed-loop deep brain stimulation of Parkinson's disease

    Science.gov (United States)

    Gorzelic, P.; Schiff, S. J.; Sinha, A.

    2013-04-01

    Objective. To explore the use of classical feedback control methods to achieve an improved deep brain stimulation (DBS) algorithm for application to Parkinson's disease (PD). Approach. A computational model of PD dynamics was employed to develop model-based rational feedback controller design. The restoration of thalamocortical relay capabilities to patients suffering from PD is formulated as a feedback control problem with the DBS waveform serving as the control input. Two high-level control strategies are tested: one that is driven by an online estimate of thalamic reliability, and another that acts to eliminate substantial decreases in the inhibition from the globus pallidus interna (GPi) to the thalamus. Control laws inspired by traditional proportional-integral-derivative (PID) methodology are prescribed for each strategy and simulated on this computational model of the basal ganglia network. Main Results. For control based upon thalamic reliability, a strategy of frequency proportional control with proportional bias delivered the optimal control achieved for a given energy expenditure. In comparison, control based upon synaptic inhibitory output from the GPi performed very well in comparison with those of reliability-based control, with considerable further reduction in energy expenditure relative to that of open-loop DBS. The best controller performance was amplitude proportional with derivative control and integral bias, which is full PID control. We demonstrated how optimizing the three components of PID control is feasible in this setting, although the complexity of these optimization functions argues for adaptive methods in implementation. Significance. Our findings point to the potential value of model-based rational design of feedback controllers for Parkinson's disease.

  17. A mouse model of pathological small intestinal epithelial cell apoptosis and shedding induced by systemic administration of lipopolysaccharide

    Directory of Open Access Journals (Sweden)

    Jonathan M. Williams

    2013-11-01

    The gut barrier, composed of a single layer of intestinal epithelial cells (IECs held together by tight junctions, prevents the entrance of harmful microorganisms, antigens and toxins from the gut lumen into the blood. Small intestinal homeostasis is normally maintained by the rate of shedding of senescent enterocytes from the villus tip exactly matching the rate of generation of new cells in the crypt. However, in various localized and systemic inflammatory conditions, intestinal homeostasis can be disturbed as a result of increased IEC shedding. Such pathological IEC shedding can cause transient gaps to develop in the epithelial barrier and result in increased intestinal permeability. Although pathological IEC shedding has been implicated in the pathogenesis of conditions such as inflammatory bowel disease, our understanding of the underlying mechanisms remains limited. We have therefore developed a murine model to study this phenomenon, because IEC shedding in this species is morphologically analogous to humans. IEC shedding was induced by systemic lipopolysaccharide (LPS administration in wild-type C57BL/6 mice, and in mice deficient in TNF-receptor 1 (Tnfr1−/−, Tnfr2 (Tnfr2−/−, nuclear factor kappa B1 (Nfκb1−/− or Nfĸb2 (Nfĸb2−/−. Apoptosis and cell shedding was quantified using immunohistochemistry for active caspase-3, and gut-to-circulation permeability was assessed by measuring plasma fluorescence following fluorescein-isothiocyanate–dextran gavage. LPS, at doses ≥0.125 mg/kg body weight, induced rapid villus IEC apoptosis, with peak cell shedding occurring at 1.5 hours after treatment. This coincided with significant villus shortening, fluid exudation into the gut lumen and diarrhea. A significant increase in gut-to-circulation permeability was observed at 5 hours. TNFR1 was essential for LPS-induced IEC apoptosis and shedding, and the fate of the IECs was also dependent on NFκB, with signaling via NFκB1 favoring cell survival and

  18. Decision tree based knowledge acquisition and failure diagnosis using a PWR loop vibration model

    International Nuclear Information System (INIS)

    Bauernfeind, V.; Ding, Y.

    1993-01-01

    An analytical vibration model of the primary system of a 1300 MW PWR was used for simulating mechanical faults. Deviations in the calculated power density spectra and coherence functions are determined and classified. The decision tree technique is then used for a personal computer supported knowledge presentation and for optimizing the logical relationships between the simulated faults and the observed symptoms. The optimized decision tree forms the knowledge base and can be used to diagnose known cases as well as to include new data into the knowledge base if new faults occur. (author)

  19. Structural modeling of DNA mini-hairpin molecules with various loop sequences

    Science.gov (United States)

    Nakamura, Shugo; Hirose, Hitoshi; Ikeguchi, Mitsunori; Shimizu, Kentaro

    1999-07-01

    We modeled the structures of DNA fragments dGC(GNA)GC (N = A, G, T, and C), which are known to form mini-hairpins, and dGC(GAC)GC and dGC(GAG)GC, which are known not to form mini-hairpins, by using global optimization of conformational energy. For all of the fragments, we obtained mini-hairpins which had similar backbone structures and positions of bases. The conformational energy differences between the energy-optimized structures were small. Our results suggest that the optimized energy values are not sufficient to discriminate which fragments form thermo-stable mini-hairpins and which do not.

  20. Intestinal absorption of aloin, aloe-emodin, and aloesin; A comparative study using two in vitro absorption models.

    Science.gov (United States)

    Park, Mi-Young; Kwon, Hoon-Jeong; Sung, Mi-Kyung

    2009-01-01

    Aloe products are one of the top selling health-functional foods in Korea, however the adequate level of intake to achieve desirable effects are not well understood. The objective of this study was to determine the intestinal uptake and metabolism of physiologically active aloe components using in vitro intestinal absorption model. The Caco-2 cell monolayer and the everted gut sac were incubated with 5-50 microM of aloin, aloe-emodin, and aloesin. The basolateral appearance of test compounds and their glucuronosyl or sulfated forms were quantified using HPLC. The % absorption of aloin, aloe-emodin, and aloesin was ranged from 5.51% to 6.60%, 6.60% to 11.32%, and 7.61% to 13.64%, respectively. Up to 18.15%, 18.18%, and 38.86% of aloin, aloe-emodin, and aloesin, respectively, was absorbed as glucuronidated or sulfated form. These results suggest that a significant amount is transformed during absorption. The absorption rate of test compounds except aloesin was similar in two models; more aloesin was absorbed in the everted gut sac than in the Caco-2 monolayer. These results provide information to establish adequate intake level of aloe supplements to maintain effective plasma level.

  1. One-loop and D-instanton corrections to the effective action of open string models

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt-Sommerfeld, Maximilian

    2009-07-02

    Methods for the calculation of certain corrections to effective actions, which comprehend the low-energy physics of string compactifications with open strings, are explained. First the shape of such actions is describes and some examples for compactifications are presented, especially a type I string model to which a dual model on the base of the heterotic string is known. Then corrections on the gauge coupling constant and on the gauge-kinetic function are discussed. general procedures for their calculation are sketched and applied to some models. The explicitly determinded corrections depend non-holomorphically on the moduli of the compactification manifold. It is explained that this is not in disagreement on the holomorphy of the gauge-kinetic function and how the latter can be extracted from the calculated results. Next D-instantons and their influence on the low-energy action are detailedly analyzed, whereby the zero modes of the instantons and global Abelian symmetries play a central role. A formula for the caclulation of scattering matrix elements in instanton sectors is given. It is to be expected that the considered instantons contribute to the superpotential of the low-energy action. However from the formula it becomes not immediately clear, how far this is possible. The mentioned formula seems to lead to expressions, which are in disagreement to the holomorphy of the superpotential. It is shown that non-holomorphic terms partly simplify, partly are so composed that the result is in accordance with the holomorphy of the superpotential. The D-instanton calculus is then used in order to derive the ADS superpotential, which is known from field theory. That this is possible is to be considered as successful test of the instanton calculus. D-instanton corrections to the gauge-kinetic functions are considered. S duality between the type I and the heterotic string is used in order to determine how the structure of the zero modes of the relevant instantons looks

  2. Intestinal Ischemia

    Science.gov (United States)

    ... weight loss Intestinal ischemia Symptoms & causes Diagnosis & treatment Advertisement Mayo Clinic does not endorse companies or products. ... a Job Site Map About This Site Twitter Facebook Google YouTube Pinterest Mayo Clinic is a not- ...

  3. Bench Test Model of the Human Skull for Testing the Variable Frequency Pulse Phase-Locked Loop Instrument

    National Research Council Canada - National Science Library

    Burin, Amy

    1996-01-01

    The Variable Frequency Pulse Phase-Locked Loop (VFPPLL) instrument is currently being used to non-invasively evaluate the human skull for increases in intracranial distances brought about by increases in intracranial pressure...

  4. Intestinal obstruction in germ-free dogs.

    Science.gov (United States)

    Heneghan, J B; Robinson, J W; Menge, H; Winistörfer, B

    1981-08-01

    Mechanical occlusions were created in the intestines of four germ-free dogs. At the time of the operation, a control loop of mid-intestine was perfused in vivo and then excised for examinations in vitro, which included the determination of the equilibrium uptake of phenylalanine and of beta-methyl-glucoside, the influx kinetics of phenylalanine and morphometric analysis of the mucosa by microdissection and stereological techniques. Seven days after establishment of the occlusion the abdomen was reopened, and loops above and below the occlusion were perfused, and then excised for the same tests in vitro. Unlike occluded loops of conventional dogs, the intestine of the germ-free animal above the occlusion does not secrete water and electrolytes into the lumen. Its transport properties in vitro do not differ from those of the control loop, and the morphometric analyses reveal only slight changes in villus structure. The loop below the obstruction undergoes marked atrophy, as has been observed in conventional dogs. The results suggest that the copious secretion that occurs above an intestinal obstruction in normal animals is due to the presence of an abundant bacterial population in the obstruction fluid.

  5. Effects of Tylosin on Bacterial Mucolysis, Clostridium perfringens Colonization, and Intestinal Barrier Function in a Chick Model of Necrotic Enteritis

    Science.gov (United States)

    Collier, C. T.; van der Klis, J. D.; Deplancke, B.; Anderson, D. B.; Gaskins, H. R.

    2003-01-01

    Necrotic enteritis (NE) is a worldwide poultry disease caused by the alpha toxin-producing bacterium Clostridium perfringens. Disease risk factors include concurrent coccidial infection and the dietary use of cereal grains high in nonstarch polysaccharides (NSP), such as wheat, barley, rye, and oats. Outbreaks of NE can be prevented or treated by the use of in-feed antibiotics. However, the current debate regarding the prophylactic use of antibiotics in animal diets necessitates a better understanding of factors that influence intestinal colonization by C. perfringens as well as the pathophysiological consequences of its growth. We report a study with a chick model of NE, which used molecular (16S rRNA gene [16S rDNA]) and culture-based microbiological techniques to investigate the impact of the macrolide antibiotic tylosin phosphate (100 ppm) and a dietary NSP (pectin) on the community structure of the small intestinal microbiota relative to colonization by C. perfringens. The effects of tylosin and pectin on mucolytic activity of the microbiota and C. perfringens colonization and their relationship to pathological indices of NE were of particular interest. The data demonstrate that tylosin reduced the percentage of mucolytic bacteria in general and the concentration of C. perfringens in particular, and these responses correlated in a temporal fashion with a reduction in the occurrence of NE lesions and an improvement in barrier function. The presence of pectin did not significantly affect the variables measured. Thus, it appears that tylosin can control NE through its modulation of C. perfringens colonization and the mucolytic activity of the intestinal microbiota. PMID:14506046

  6. In vitro gastrointestinal digestion increases the translocation of polystyrene nanoparticles in an in vitro intestinal co-culture model.

    Science.gov (United States)

    Walczak, Agata P; Kramer, Evelien; Hendriksen, Peter J M; Helsdingen, Richard; van der Zande, Meike; Rietjens, Ivonne M C M; Bouwmeester, Hans

    2015-01-01

    The conditions of the gastrointestinal tract may change the physicochemical properties of nanoparticles (NPs) and therewith the bioavailability of orally taken NPs. Therefore, we assessed the impact of in vitro gastrointestinal digestion on the protein corona of polystyrene NPs (PS-NPs) and their subsequent translocation across an in vitro intestinal barrier. A co-culture of intestinal Caco-2 and HT29-MTX cells was exposed to 50 nm PS-NPs of different charges (positive and negative) in two forms: pristine and digested in an in vitro gastrointestinal digestion model. In vitro digestion significantly increased the translocation of all, except the "neutral", PS-NPs. Upon in vitro digestion, translocation was 4-fold higher for positively charged NPs and 80- and 1.7-fold higher for two types of negatively charged NPs. Digestion significantly reduced the amount of protein in the corona of three out of four types of NPs. This reduction of proteins was 4.8-fold for "neutral", 3.5-fold for positively charged and 1.8-fold for one type of negatively charged PS-NPs. In vitro digestion also affected the composition of the protein corona of PS-NPs by decreasing the presence of higher molecular weight proteins and shifting the protein content of the corona to low molecular weight proteins. These findings are the first to report that in vitro gastrointestinal digestion significantly affects the protein corona and significantly increases the in vitro translocation of differently charged PS-NPs. These findings stress the importance of including the in vitro digestion in future in vitro intestinal translocation screening studies for risk assessment of orally taken NPs.

  7. Elevation of HO-1 Expression Mitigates Intestinal Ischemia-Reperfusion Injury and Restores Tight Junction Function in a Rat Liver Transplantation Model

    Directory of Open Access Journals (Sweden)

    Xinjin Chi

    2015-01-01

    Full Text Available Aims. This study was aimed at investigating whether elevation of heme oxygenase-1 (HO-1 expression could lead to restoring intestinal tight junction (TJ function in a rat liver transplantation model. Methods. Intestinal mucosa injury was induced by orthotopic autologous liver transplantation (OALT on male Sprague-Dawley rats. Hemin (a potent HO-1 activator and zinc-protoporphyrin (ZnPP, a HO-1 competitive inhibitor, were separately administered in selected groups before OALT. The serum and intestinal mucosa samples were collected at 8 hours after the operation for analysis. Results. Hemin pretreatment significantly reduced the inflammation and oxidative stress in the mucosal tissue after OALT by elevating HO-1 protein expression, while ZnPP pretreatment aggravated the OALT mucosa injury. Meanwhile, the restriction on the expression of tight junction proteins zonula occludens-1 and occludin was removed after hemin pretreatment. These molecular events led to significant improvement on intestinal barrier function, which was proved to be through increasing nuclear translocation of nuclear factor-E2-related factor 2 (Nrf2 and reducing nuclear translocation of nuclear factor kappa-B (NF-κB in intestinal injured mucosa. Summary. Our study demonstrated that elevation of HO-1 expression reduced the OALT-induced intestinal mucosa injury and TJ dysfunction. The HO-1 protective function was likely mediated through its effects of anti-inflammation and antioxidative stress.

  8. Elevation of HO-1 Expression Mitigates Intestinal Ischemia-Reperfusion Injury and Restores Tight Junction Function in a Rat Liver Transplantation Model

    Science.gov (United States)

    Chi, Xinjin; Yao, Weifeng; Xia, Hua; Jin, Yi; Li, Xi; Cai, Jun; Hei, Ziqing

    2015-01-01

    Aims. This study was aimed at investigating whether elevation of heme oxygenase-1 (HO-1) expression could lead to restoring intestinal tight junction (TJ) function in a rat liver transplantation model. Methods. Intestinal mucosa injury was induced by orthotopic autologous liver transplantation (OALT) on male Sprague-Dawley rats. Hemin (a potent HO-1 activator) and zinc-protoporphyrin (ZnPP, a HO-1 competitive inhibitor), were separately administered in selected groups before OALT. The serum and intestinal mucosa samples were collected at 8 hours after the operation for analysis. Results. Hemin pretreatment significantly reduced the inflammation and oxidative stress in the mucosal tissue after OALT by elevating HO-1 protein expression, while ZnPP pretreatment aggravated the OALT mucosa injury. Meanwhile, the restriction on the expression of tight junction proteins zonula occludens-1 and occludin was removed after hemin pretreatment. These molecular events led to significant improvement on intestinal barrier function, which was proved to be through increasing nuclear translocation of nuclear factor-E2-related factor 2 (Nrf2) and reducing nuclear translocation of nuclear factor kappa-B (NF-κB) in intestinal injured mucosa. Summary. Our study demonstrated that elevation of HO-1 expression reduced the OALT-induced intestinal mucosa injury and TJ dysfunction. The HO-1 protective function was likely mediated through its effects of anti-inflammation and antioxidative stress. PMID:26064429

  9. Saccharomyces cerevisiae strain UFMG 905 protects against bacterial translocation, preserves gut barrier integrity and stimulates the immune system in a murine intestinal obstruction model.

    Science.gov (United States)

    Generoso, Simone V; Viana, Mirelle; Santos, Rosana; Martins, Flaviano S; Machado, José A N; Arantes, Rosa M E; Nicoli, Jacques R; Correia, Maria I T D; Cardoso, Valbert N

    2010-06-01

    Probiotic is a preparation containing microorganisms that confers beneficial effect to the host. This work assessed whether oral treatment with viable or heat-killed yeast Saccharomyces cerevisiae strain UFMG 905 prevents bacterial translocation (BT), intestinal barrier integrity, and stimulates the immunity, in a murine intestinal obstruction (IO) model. Four groups of mice were used: mice undergoing only laparotomy (CTL), undergoing intestinal obstruction (IO) and undergoing intestinal obstruction after previous treatment with viable or heat-killed yeast. BT, determined as uptake of (99m)Tc-E. coli in blood, mesenteric lymph nodes, liver, spleen and lungs, was significantly higher in IO group than in CTL group. Treatments with both yeasts reduced BT in blood and all organs investigated. The treatment with both yeasts also reduced intestinal permeability as determined by blood uptake of (99m)Tc-DTPA. Immunological data demonstrated that both treatments were able to significantly increase IL-10 levels, but only viable yeast had the same effect on sIgA levels. Intestinal lesions were more severe in IO group when compared to CTL and yeasts groups. Concluding, both viable and heat-killed cells of yeast prevent BT, probably by immunomodulation and by maintaining gut barrier integrity. Only the stimulation of IgA production seems to depend on the yeast viability.

  10. The effect of ulinastatin on the small intestine injury and mast cell degranulation in a rat model of sepsis induced by CLP.

    Science.gov (United States)

    Zhang, Yi-Jing; Li, Ming; Meng, Mei; Feng, Mei; Qin, Cheng-Yong

    2009-09-01

    Sepsis could be initiated by the gastrointestinal tract injury and subsequent bacterial translocation. In the present experiment, we aimed to investigate effect of ulinastatin (UTI) on the small intestinal injury and bacterial translocation in septic rats and role of mast cells degranulation in its action. Fifty-four male Wistar rats were randomly divided into three groups: sham laparatomy, cecal ligation and puncture (CLP), and CLP plus UTI. CLP was used to develop septic rat model and UTI was administered to rats intraperitoneally (50,000 U/kg) 30 min prior to CLP operation. After CLP or sham operation, variable parameters were investigated in three subsets of animals. One subset was used for measurements of nitrite and nitrate (NO(x)) concentration in plasma at 1, 6, 12, 18, and 24h and levels of NO(x) and iNOS mRNA in the small intestine, RMCP-II released into the small intestinal lumen, bacterial translocation and morphologic changes at 24h. The other subsets were used for the small intestinal motility and microvascular in vivo at 24h. Bacterial translocation, barrier injury, impaired motility and blood flow, mast cells degranulation of the small intestine in the CLP group were found more severe than that in the sham group. Elevated RMCP-II, NO(x), and iNOS mRNA levels were also detected in the CLP group. Application of UTI not only protected the small intestine from sepsis but also diminished changes of intestinal mast cells. UTI can significantly ameliorate the small intestinal injury and subsequent bacterial translocation by inhibiting mast cells degranulation in septic rats.

  11. Intestinal Coccidia

    OpenAIRE

    MJ Ggaravi

    2007-01-01

    Intestinal Coccidia are a subclass of Apicomplexa phylum. Eucoccidida are facultative heteroxenous, but some of them are monoxenous. They have sexual and asexual life cycle. Some coccidia are human pathogens, for example: Cryptosporidium: Cryptosporidiums has many species that are mammalian intestinal parasites.C. Parvum specie is a human pathogenic protozoa. Cryptosporidum has circle or ellipse shapes and nearly 4-6 mm. It is transmitted in warm seasons. Oocyst is obtained insexual life cycl...

  12. Simulation Loop between CAD systems, Geant4 and GeoModel: Implementation and Results

    CERN Document Server

    Sharmazanashvili, Alexander; The ATLAS collaboration

    2015-01-01

    Data_vs_MonteCarlo discrepancy is one of the most important field of investigation for ATLAS simulation studies. There are several reasons of above mentioned discrepancies but primary interest is falling on geometry studies and investigation of how geometry descriptions of detector in simulation adequately representing “as-built” descriptions. Shapes consistency and detalization is not important while adequateness of volumes and weights of detector components are essential for tracking. There are 2 main reasons of faults of geometry descriptions in simulation: 1/ Inconsistency to “as-built” geometry descriptions; 2/Internal inaccuracies of transactions added by simulation packages itself. Georgian Engineering team developed hub on the base of CATIA platform and several tools enabling to read in CATIA different descriptions used by simulation packages, like XML/Persint->CATIA; IV/VP1->CATIA; GeoModel->CATIA; Geant4->CATIA. As a result it becomes possible to compare different descriptions with each othe...

  13. Designing Closed-Loop Brain-Machine Interfaces Using Model Predictive Control

    Directory of Open Access Journals (Sweden)

    Gautam Kumar

    2016-06-01

    Full Text Available Brain-machine interfaces (BMIs are broadly defined as systems that establish direct communications between living brain tissue and external devices, such as artificial arms. By sensing and interpreting neuronal activities to actuate an external device, BMI-based neuroprostheses hold great promise in rehabilitating motor disabled subjects, such as amputees. In this paper, we develop a control-theoretic analysis of a BMI-based neuroprosthetic system for voluntary single joint reaching task in the absence of visual feedback. Using synthetic data obtained through the simulation of an experimentally validated psycho-physiological cortical circuit model, both the Wiener filter and the Kalman filter based linear decoders are developed. We analyze the performance of both decoders in the presence and in the absence of natural proprioceptive feedback information. By performing simulations, we show that the performance of both decoders degrades significantly in the absence of the natural proprioception. To recover the performance of these decoders, we propose two problems, namely tracking the desired position trajectory and tracking the firing rate trajectory of neurons which encode the proprioception, in the model predictive control framework to design optimal artificial sensory feedback. Our results indicate that while the position trajectory based design can only recover the position and velocity trajectories, the firing rate trajectory based design can recover the performance of the motor task along with the recovery of firing rates in other cortical regions. Finally, we extend our design by incorporating a network of spiking neurons and designing artificial sensory feedback in the form of a charged balanced biphasic stimulating current.

  14. PEMBELAJARAN MATEMATIKA MODEL DOUBLE LOOP PROBLEM SOLVING DENGAN PENDEKATAN PMRI BERMUATAN KARAKTER UNTUK MENINGKATKAN KEMAMPUAN PEMECAHAN MASALAH

    Directory of Open Access Journals (Sweden)

    Indrati Rahayu

    2014-06-01

    /construction, (4 test, evaluation and revision, and (5 implementation. The result of the study shows: (1 The learning instruments that is developed is valid, (2 the result of  experimental instrument  shows : (a the individual problem solving abilities exceed the KKM value = 70  and 93,75 % of the students can achieve above the standard  of  80%. The conclusions of  this study is the  model of  Double Loop Problem Solving Learning with PMRI to enhance the Problem Solving Abilities is a Learning Model that is valid, practical and effective.

  15. Biological NOx removal by denitrification process in a jet-loop bioreactor: system performance and model development.

    Science.gov (United States)

    Durmazpinar, Serdar; Ilhan, Nalan; Demir, Gonca; Insel, Güçlü; Dizge, Nadir; Ergenekon, Pinar; Erhan, Elif; Keskinler, Bülent

    2014-01-01

    Nitrogen monoxide (NO) and nitrogen dioxide referred as NOx are one of the most important air pollutants in the atmosphere. Biological NOx removal technologies have been developing to reach a cost-effective control method for upcoming stringent NOx emission standards. The BioDeNOx system was seen as a promising biological NOx control technology which is composed of two reactors, one for absorbing of NO in an aqueous Fe(II)EDTA2- solution and the other for subsequent reduction to N2 gas in a biological reactor by the denitrification process. In this study, instead of two discrete reactors, only one jet-loop bioreactor (JLBR) was utilized as both absorption and denitrification unit and no chelate-forming chemicals were added. In other words, the advantage of better mass transfer conditions of jet bioreactor was used instead of Fe(II)EDTA2-. The process was named as Jet-BioDeNOx. The JLBR was operated for the removal of NOx from air streams containing 500-3000 ppm NOx and the results showed that the removal efficiency was between 81% and 94%. The air to liquid flow ratio (Q(G)/Q(RAS)) varied in the range of 0.07-0.12. Mathematical modelling of the system demonstrated that the removal efficiency strongly depends on this ratio. The high mass transfer conditions prevailed in the reactor provided a competitive advantage on removing NO gas without any requirement of chelating chemicals.

  16. Rotary Bed Reactor for Chemical-Looping Combustion with Carbon Capture. Part 1: Reactor Design and Model Development

    KAUST Repository

    Zhao, Zhenlong

    2013-01-17

    Chemical-looping combustion (CLC) is a novel and promising technology for power generation with inherent CO2 capture. Currently, almost all of the research has been focused on developing CLC-based interconnected fluidized-bed reactors. In this two-part series, a new rotary reactor concept for gas-fueled CLC is proposed and analyzed. In part 1, the detailed configuration of the rotary reactor is described. In the reactor, a solid wheel rotates between the fuel and air streams at the reactor inlet and exit. Two purging sectors are used to avoid the mixing between the fuel stream and the air stream. The rotary wheel consists of a large number of channels with copper oxide coated on the inner surface of the channels. The support material is boron nitride, which has high specific heat and thermal conductivity. Gas flows through the reactor at elevated pressure, and it is heated to a high temperature by fuel combustion. Typical design parameters for a thermal capacity of 1 MW have been proposed, and a simplified model is developed to predict the performances of the reactor. The potential drawbacks of the rotary reactor are also discussed. © 2012 American Chemical Society.

  17. On the relationship between MHD equilibrium bifurcations and linear stability theory for models of line-tied coronal loops

    Science.gov (United States)

    Romeou, Z.; Neukirch, T.

    2002-10-01

    We present the results of an investigation of the relationship between the predictions made by linear MHD stability theory for instabilities of straight flux tube models of line-tied coronal loops and the bifurcations of the underlying MHD equilibria. It is found that contrary to the naive assumption that there should be a one-to-one correspondence between instability points and bifurcation points, such an one-to-one correspondence does not always exist. Using the Gold-Hoyle equilibrium as an illustrative example it is shown that additional axisymmetric bifurcations exist if the equilibrium bifurcations are calculated with Grad-Shafranov theory. In this case the onset of the m = 0-instability (sausage mode) corresponds to the second and not the first bifurcation point of the equilibrium sequence. No additional bifurcations have been found when Euler potentials are used, and in this case the first bifurcation coincides with the onset condition for the m = 0-instability. A possible reason for this difference are the different boundary conditions.

  18. Loop Mediated Isothermal Amplification for Detection of Trypanosoma brucei gambiense in Urine and Saliva Samples in Nonhuman Primate Model

    Directory of Open Access Journals (Sweden)

    Maina Ngotho

    2015-01-01

    Full Text Available Human African trypanosomiasis (HAT is a vector-borne parasitic zoonotic disease. The disease caused by Trypanosoma brucei gambiense is the most prevalent in Africa. Early diagnosis is hampered by lack of sensitive diagnostic techniques. This study explored the potential of loop mediated isothermal amplification (LAMP and polymerase chain reaction (PCR in the detection of T. b. gambiense infection in a vervet monkey HAT model. Six vervet monkeys were experimentally infected with T. b. gambiense IL3253 and monitored for 180 days after infection. Parasitaemia was scored daily. Blood, cerebrospinal fluid (CSF, saliva, and urine samples were collected weekly. PCR and LAMP were performed on serum, CSF, saliva, and urine samples. The detection by LAMP was significantly higher than that of parasitological methods and PCR in all the samples. The performance of LAMP varied between the samples and was better in serum followed by saliva and then urine samples. In the saliva samples, LAMP had 100% detection between 21 and 77 dpi, whereas in urine the detection it was slightly lower, but there was over 80% detection between 28 and 91 dpi. However, LAMP could not detect trypanosomes in either saliva or urine after 140 and 126 dpi, respectively. The findings of this study emphasize the importance of LAMP in diagnosis of HAT using saliva and urine samples.

  19. Exact third-order density perturbation and one-loop power spectrum in general dark energy models

    Directory of Open Access Journals (Sweden)

    Seokcheon Lee

    2014-09-01

    Full Text Available Under the standard perturbation theory (SPT, we obtain the fully consistent third-order density fluctuation and kernels for the general dark energy models without using the Einstein–de Sitter (EdS universe assumption for the first time. We also show that even though the temporal and spatial components of the SPT solutions cannot be separable, one can find the exact solutions to any order in general dark energy models. With these exact solutions, we obtain the less than % error correction of one-loop matter power spectrum compared to that obtained from the EdS assumption for k=0.1 hMpc−1 mode at z=0(1,1.5. Thus, the EdS assumption works very well at this scale. However, if one considers the correction for P13, the error is about 6 (9, 11% for the same mode at z=0(1,1.5. One absorbs P13 into the linear power spectrum in the renormalized perturbation theory (RPT and thus one should use the exact solution instead of the approximation one. The error on the resummed propagator N of RPT is about 14 (8, 6% at z=0(1,1.5 for k=0.4 hMpc−1. For k=1 hMpc−1, the error correction of the total matter power spectrum is about 3.6 (4.6, 4.5% at z=0(1,1.5. Upcoming observation is required to archive the sub-percent accuracy to provide the strong constraint on the dark energy and this consistent solution is prerequisite for the model comparison.

  20. H+H- interaction up to higher orders of perturbation theory in the model with two Higgs doublets (Lagrangian and one-loop amplitudes)

    International Nuclear Information System (INIS)

    Dvoeglazov, V.V.; Skachkov, N.B.

    1991-01-01

    The one-loop amplitude of the Higgs-Higgs interaction is calculated in the fourth order of perturbation theory in the framework of the model with two Higgs doublets and an arbitrary number of fermions. The Lagrangian of this interaction is taken without any approximations. The vertex coupling constants like f 3H , f HHV , etc., are taken as given by the minimal SUSY extension of the Standard Model. 7 refs.; 1 fig

  1. Altered 13C glucose metabolism in the cortico-striato-thalamo-cortical loop in the MK-801 rat model of schizophrenia

    DEFF Research Database (Denmark)

    Eyjolfsson, Elvar M; Nilsen, Linn Hege; Kondziella, Daniel

    2011-01-01

    Using a modified MK-801 (dizocilpine) N-methyl-D-aspartic acid (NMDA) receptor hypofunction model for schizophrenia, we analyzed glycolysis, as well as glutamatergic, GABAergic, and monoaminergic neurotransmitter synthesis and degradation. Rats received an injection of MK-801 daily for 6 days...... in all regions. In conclusion, neurotransmitter metabolism in the cortico-striato-thalamo-cortical loop is severely impaired in the MK-801 (dizocilpine) NMDA receptor hypofunction animal model for schizophrenia....

  2. One loop electro-weak radiative corrections in the standard model

    International Nuclear Information System (INIS)

    Kalyniak, P.; Sundaresan, M.K.

    1987-01-01

    This paper reports on the effect of radiative corrections in the standard model. A sensitive test of the three gauge boson vertices is expected to come from the work in LEPII in which the reaction e + e - → W + W - can occur. Two calculations of radiative corrections to the reaction e + e - → W + W - exist at present. The results of the calculations although very similar disagree with one another as to the actual magnitude of the correction. Some of the reasons for the disagreement are understood. However, due to the reasons mentioned below, another look must be taken at these lengthy calculations to resolve the differences between the two previous calculations. This is what is being done in the present work. There are a number of reasons why we must take another look at the calculation of the radiative corrections. The previous calculations were carried out before the UA1, UA2 data on W and Z bosons were obtained. Experimental groups require a computer program which can readily calculate the radiative corrections ab initio for various experimental conditions. The normalization of sin 2 θ w in the previous calculations was done in a way which is not convenient for use in the experimental work. It would be desirable to have the analytical expressions for the corrections available so that the renormalization scheme dependence of the corrections could be studied

  3. Ecological modeling from time-series inference: insight into dynamics and stability of intestinal microbiota.

    Directory of Open Access Journals (Sweden)

    Richard R Stein

    Full Text Available The intestinal microbiota is a microbial ecosystem of crucial importance to human health. Understanding how the microbiota confers resistance against enteric pathogens and how antibiotics disrupt that resistance is key to the prevention and cure of intestinal infections. We present a novel method to infer microbial community ecology directly from time-resolved metagenomics. This method extends generalized Lotka-Volterra dynamics to account for external perturbations. Data from recent experiments on antibiotic-mediated Clostridium difficile infection is analyzed to quantify microbial interactions, commensal-pathogen interactions, and the effect of the antibiotic on the community. Stability analysis reveals that the microbiota is intrinsically stable, explaining how antibiotic perturbations and C. difficile inoculation can produce catastrophic shifts that persist even after removal of the perturbations. Importantly, the analysis suggests a subnetwork of bacterial groups implicated in protection against C. difficile. Due to its generality, our method can be applied to any high-resolution ecological time-series data to infer community structure and response to external stimuli.

  4. Effect of bacteriocin-producing lactobacilli on the survival of Escherichia coli and Listeria in a dynamic model of the stomach and the small intestine

    NARCIS (Netherlands)

    Gänzle, M.G.; Hertel, C.; Vossen, J.M.B.M. van der; Hammes, W.P.

    1999-01-01

    The survival of Lactobacillus curvatus LTH 1174 (bac+) and (bac-) in combination with Escherichia coli LTH 1600 or Listeria innocua DSM20649 during transit through a dynamic model of the human stomach and small intestine (GIT model) was studied. Furthermore, we determined the digestion of curvacin A

  5. Alternative loop rings

    CERN Document Server

    Goodaire, EG; Polcino Milies, C

    1996-01-01

    For the past ten years, alternative loop rings have intrigued mathematicians from a wide cross-section of modern algebra. As a consequence, the theory of alternative loop rings has grown tremendously. One of the main developments is the complete characterization of loops which have an alternative but not associative, loop ring. Furthermore, there is a very close relationship between the algebraic structures of loop rings and of group rings over 2-groups. Another major topic of research is the study of the unit loop of the integral loop ring. Here the interaction between loop rings and group ri

  6. Colonization resistance and microbial ecophysiology: using gnotobiotic mouse models and single-cell technology to explore the intestinal jungle.

    Science.gov (United States)

    Stecher, Bärbel; Berry, David; Loy, Alexander

    2013-09-01

    The highly diverse intestinal microbiota forms a structured community engaged in constant communication with itself and its host and is characterized by extensive ecological interactions. A key benefit that the microbiota affords its host is its ability to protect against infections in a process termed colonization resistance (CR), which remains insufficiently understood. In this review, we connect basic concepts of CR with new insights from recent years and highlight key technological advances in the field of microbial ecology. We present a selection of statistical and bioinformatics tools used to generate hypotheses about synergistic and antagonistic interactions in microbial ecosystems from metagenomic datasets. We emphasize the importance of experimentally testing these hypotheses and discuss the value of gnotobiotic mouse models for investigating specific aspects related to microbiota-host-pathogen interactions in a well-defined experimental system. We further introduce new developments in the area of single-cell analysis using fluorescence in situ hybridization in combination with metabolic stable isotope labeling technologies for studying the in vivo activities of complex community members. These approaches promise to yield novel insights into the mechanisms of CR and intestinal ecophysiology in general, and give researchers the means to experimentally test hypotheses in vivo at varying levels of biological and ecological complexity. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  7. Intestinal Absorption of Triterpenoids and Flavonoids from Glycyrrhizae radix et rhizoma in the Human Caco-2 Monolayer Cell Model.

    Science.gov (United States)

    Wang, Xiao-Xue; Liu, Gui-Yan; Yang, Yan-Fang; Wu, Xiu-Wen; Xu, Wei; Yang, Xiu-Wei

    2017-09-29

    Glycyrrhizae radix et rhizoma has been used as a traditional Chinese medicine for the treatment of various diseases. Triterpenoids and flavonoids from the plant have many beneficial effects and their chemical structures are modified in the gastrointestinal tract after oral administration. However, absorption of these triterpenoids and flavonoids still needs to be defined. Here, the uptake and transepithelial transport of the selected major triterpenoids, glycyrrhizin ( 1 ), glycyrrhetic acid-3- O -mono-β-d-glucuronide ( 2 ), and glycyrrhetinic acid ( 3 ); and the selected major flavonoids, licochalcone A ( 4 ), licochalcone B ( 5 ), licochalcone C ( 6 ), echinatin ( 7 ), isoliquiritin apioside ( 8 ), liquiritigenin ( 9 ), liquiritin apioside ( 10 ) isolated from Glycyrrhizae radix et rhizoma , were investigated in the human intestinal epithelium-like Caco-2 cell monolayer model. Compounds 3 , 5 - 7 , and 9 were designated as well-absorbed compounds, 2 and 4 were designated as moderately absorbed ones, and 1 , 8 , and 10 were assigned for the poorly absorbed ones. The absorption mechanism of well and moderately absorbed compound was mainly passive diffusion to pass through the human intestinal Caco-2 cell monolayer. These findings provided useful information for predicting their oral bioavailability and the clinical application.

  8. The anti-epileptic drug substance vigabatrin inhibits taurine transport in intestinal and renal cell culture models

    DEFF Research Database (Denmark)

    Plum, Jakob Munk; Nøhr, Martha Kampp; Hansen, Steen H

    2014-01-01

    , such evidence does not preclude the involvement of other transporters. The aim of the present study was, therefore, to investigate if vigabatrin interacts with taurine transport. The uptake of taurine was measured in intestinal human Caco-2 and canine MDCK cell monolayers in the absence or presence of amino...... acids such as GABA and vigabatrin. Vigabatrin inhibits the uptake of taurine in Caco-2 and MDCK cells to 34±3 and 53±2%, respectively, at a concentration of 30mM. In Caco-2 cells the uptake of vigabatrin under neutral pH conditions is concentration-dependent and saturable with a Km-value of 27mM (log......Km is 1.43±0.09). In conclusion, the present study shows that vigabatrin was able to inhibit the uptake of taurine in intestinal and renal cell culture models. Furthermore, uptake of vigabatrin in Caco-2 cells under neutral pH conditions was concentration-dependent and saturable and suggesting...

  9. Small Intestine Disorders

    Science.gov (United States)

    ... disease Crohn's disease Infections Intestinal cancer Intestinal obstruction Irritable bowel syndrome Ulcers, such as peptic ulcer Treatment of disorders of the small intestine depends on the cause.

  10. BMN correlators by loop equations

    International Nuclear Information System (INIS)

    Eynard, Bertrand; Kristjansen, Charlotte

    2002-01-01

    In the BMN approach to N=4 SYM a large class of correlators of interest are expressible in terms of expectation values of traces of words in a zero-dimensional gaussian complex matrix model. We develop a loop-equation based, analytic strategy for evaluating such expectation values to any order in the genus expansion. We reproduce the expectation values which were needed for the calculation of the one-loop, genus one correction to the anomalous dimension of BMN-operators and which were earlier obtained by combinatorial means. Furthermore, we present the expectation values needed for the calculation of the one-loop, genus two correction. (author)

  11. Intestinal anti-inflammatory activity of ellagic acid in the acute and chronic dextrane sulfate sodium models of mice colitis.

    Science.gov (United States)

    Marín, Marta; María Giner, Rosa; Ríos, José-Luis; Recio, María Carmen

    2013-12-12

    Pomegranate (Punica granatum L.; Lythraceae) has traditionally been used for the treatment of various inflammatory diseases, including ulcerative colitis (UC). Because its fruits and extracts are rich in ellagitannins, which release ellagic acid when hydrolyzed, consumption of pomegranate products is currently being widely promoted for their potential health effects, including the prevention of inflammatory diseases and cancer. To evaluate the anti-inflammatory effects of ellagic acid on dextran sulfate sodium (DSS)-induced acute and chronic experimental colitis in two different strains of mice and to elucidate its possible mechanisms of action. In the acute UC model, female Balb/C mice were treated with DSS (5%) for seven days while concomitantly receiving a dietary supplement of ellagic acid (2%). In the chronic UC model, female C57BL/6 mice received four week-long cycles of DSS (1% and 2%) interspersed with week-long recovery periods along with a diet supplemented with ellagic acid (0.5%). In acute model of UC, ellagic acid ameliorated disease severity slightly as observed both macroscopically and through the profile of inflammatory mediators (IL-6, TNF-α, and IFN-γ). In the chronic UC model, ellagic acid significantly inhibited the progression of the disease, reducing intestinal inflammation and decreasing histological scores. Moreover, mediators such as COX-2 and iNOS were downregulated and the signaling pathways p38 MAPK, NF-κB, and STAT3 were blocked. Our study reinforces the hypothetical use of ellagic acid as an anti-inflammatory complement to conventional UC treatment in chronic UC patients and could be considered in the dietary prevention of intestinal inflammation and related cancer development. © 2013 Published by Elsevier Ireland Ltd.

  12. Infliximab's influence on anastomotic strength and degree of inflammation in intestinal surgery in a rabbit model

    DEFF Research Database (Denmark)

    Frostberg, Erik; Ström, Petter; Gerke, Oke

    2014-01-01

    BACKGROUND: Infliximab, a TNF-alpha inhibitor, is a potent anti-inflammatory drug in the treatment of inflammatory bowel diseases. Recent studies have investigated the effect of infliximab treatment on postoperative complications such as anastomotic leakage, however, with conflicting results...... and conclusions. The purpose of this study was to investigate whether a single dose infliximab has an adverse effect on the anastomotic healing process, observed as reduced anastomotic breaking strength and histopathologically verified lower grade of inflammatory response, in the small intestine of a rabbit....... METHODS: Thirty New Zealand rabbits (median weight 2.5 kg) were allocated to treatment with an intravenous bolus of either 10 mg/kg infliximab (n = 15) or placebo (n = 15). One week later all rabbits underwent two separate end-to-end anastomoses in the jejunum under general anesthesia. At postoperative...

  13. Models for Incretin Research: From the Intestine to the Whole Body

    Directory of Open Access Journals (Sweden)

    Tae Jung Oh

    2016-03-01

    Full Text Available Incretin hormones are produced by enteroendocrine cells (EECs in the intestine in response to ingested nutrient stimuli. The incretin effect is defined as the difference in the insulin secretory response between the oral glucose tolerance test and an isoglycemic intravenous glucose infusion study. The pathophysiology of the decreased incretin effect has been studied as decreased incretin sensitivity and/or β-cell dysfunction per se. Interestingly, robust increases in endogenous incretin secretion have been observed in many types of metabolic/bariatric surgery. Therefore, metabolic/bariatric surgery has been extensively studied for incretin physiology, not only the hormones themselves but also alterations in EECs distribution and genetic expression levels of gut hormones. These efforts have given us an enormous understanding of incretin biology from synthesis to in vivo behavior. Further innovative studies are needed to determine the mechanisms and targets of incretin hormones.

  14. Inhibition of intestinal epithelial apoptosis improves survival in a murine model of radiation combined injury.

    Science.gov (United States)

    Jung, Enjae; Perrone, Erin E; Brahmamdan, Pavan; McDonough, Jacquelyn S; Leathersich, Ann M; Dominguez, Jessica A; Clark, Andrew T; Fox, Amy C; Dunne, W Michael; Hotchkiss, Richard S; Coopersmith, Craig M

    2013-01-01

    World conditions place large populations at risk from ionizing radiation (IR) from detonation of dirty bombs or nuclear devices. In a subgroup of patients, ionizing radiation exposure would be followed by a secondary infection. The effects of radiation combined injury are potentially more lethal than either insult in isolation. The purpose of this study was to determine mechanisms of mortality and possible therapeutic targets in radiation combined injury. Mice were exposed to IR with 2.5 Gray (Gy) followed four days later by intratracheal methicillin-resistant Staphylococcus aureus (MRSA). While either IR or MRSA alone yielded 100% survival, animals with radiation combined injury had 53% survival (p = 0.01). Compared to IR or MRSA alone, mice with radiation combined injury had increased gut apoptosis, local and systemic bacterial burden, decreased splenic CD4 T cells, CD8 T cells, B cells, NK cells, and dendritic cells, and increased BAL and systemic IL-6 and G-CSF. In contrast, radiation combined injury did not alter lymphocyte apoptosis, pulmonary injury, or intestinal proliferation compared to IR or MRSA alone. In light of the synergistic increase in gut apoptosis following radiation combined injury, transgenic mice that overexpress Bcl-2 in their intestine and wild type mice were subjected to IR followed by MRSA. Bcl-2 mice had decreased gut apoptosis and improved survival compared to WT mice (92% vs. 42%; p<0.01). These data demonstrate that radiation combined injury results in significantly higher mortality than could be predicted based upon either IR or MRSA infection alone, and that preventing gut apoptosis may be a potential therapeutic target.

  15. Restoration of a healthy intestinal microbiota normalizes portal hypertension in a rat model of nonalcoholic steatohepatitis.

    Science.gov (United States)

    García-Lezana, Teresa; Raurell, Imma; Bravo, Miren; Torres-Arauz, Manuel; Salcedo, María Teresa; Santiago, Alba; Schoenenberger, Andreu; Manichanh, Chaysavanh; Genescà, Joan; Martell, María; Augustin, Salvador

    2018-04-01

    Portal hypertension (PH) drives most of the clinical complications in chronic liver diseases. However, its progression in nonalcoholic steatohepatitis (NASH) and its association with the intestinal microbiota (IM) have been scarcely studied. Our aim was to investigate the role of the IM in the mechanisms leading to PH in early NASH. The experimental design was divided in two stages. In stage 1, Sprague-Dawley rats were fed for 8 weeks a high-fat, high-glucose/fructose diet (HFGFD) or a control diet/water (CD). Representative rats were selected as IM donors for stage 2. In stage 2, additional HFGFD and CD rats underwent intestinal decontamination, followed by IM transplantation with feces from opposite-diet donors (heterologous transplant) or autologous fecal transplant (as controls), generating four groups: CD-autotransplanted, CD-transplanted, HFGFD-autotransplanted, HFGFD-transplanted. After IM transplantation, the original diet was maintained for 12-14 days until death. HFGFD rats developed obesity, insulin resistance, NASH without fibrosis but with PH, intrahepatic endothelial dysfunction, and IM dysbiosis. In HFGFD rats, transplantation with feces from CD donors caused a significant reduction of PH to levels comparable to CD without significant changes in NASH histology. The reduction in PH was due to a 31% decrease of intrahepatic vascular resistance compared to the HFGFD-autotransplanted group (P protein kinase B-dependent endothelial nitric oxide synthase signaling pathway. The IM exerts a direct influence in the development of PH in rats with diet-induced NASH and dysbiosis; PH, insulin resistance, and endothelial dysfunction revert when a healthy IM is restored. (Hepatology 2018;67:1485-1498). © 2017 by the American Association for the Study of Liver Diseases.

  16. Inhibition of intestinal epithelial apoptosis improves survival in a murine model of radiation combined injury.

    Directory of Open Access Journals (Sweden)

    Enjae Jung

    Full Text Available World conditions place large populations at risk from ionizing radiation (IR from detonation of dirty bombs or nuclear devices. In a subgroup of patients, ionizing radiation exposure would be followed by a secondary infection. The effects of radiation combined injury are potentially more lethal than either insult in isolation. The purpose of this study was to determine mechanisms of mortality and possible therapeutic targets in radiation combined injury. Mice were exposed to IR with 2.5 Gray (Gy followed four days later by intratracheal methicillin-resistant Staphylococcus aureus (MRSA. While either IR or MRSA alone yielded 100% survival, animals with radiation combined injury had 53% survival (p = 0.01. Compared to IR or MRSA alone, mice with radiation combined injury had increased gut apoptosis, local and systemic bacterial burden, decreased splenic CD4 T cells, CD8 T cells, B cells, NK cells, and dendritic cells, and increased BAL and systemic IL-6 and G-CSF. In contrast, radiation combined injury did not alter lymphocyte apoptosis, pulmonary injury, or intestinal proliferation compared to IR or MRSA alone. In light of the synergistic increase in gut apoptosis following radiation combined injury, transgenic mice that overexpress Bcl-2 in their intestine and wild type mice were subjected to IR followed by MRSA. Bcl-2 mice had decreased gut apoptosis and improved survival compared to WT mice (92% vs. 42%; p<0.01. These data demonstrate that radiation combined injury results in significantly higher mortality than could be predicted based upon either IR or MRSA infection alone, and that preventing gut apoptosis may be a potential therapeutic target.

  17. Prediction of induction time for methane hydrate formation in the presence or absence of THF in flow loop system by Natarajan model

    Science.gov (United States)

    Talaghat, Mohammad Reza; Jokar, Seyyed Mohammad

    2018-03-01

    The induction time is a time interval to detect the initial hydrate formation, which is counted from the moment when the stirrer is turned on until the first detection of hydrate formation. The main objective of the present work is to predict and measure the induction time of methane hydrate formation in the presence or absence of tetrahydrofuran (THF) as promoter in the flow loop system. A laboratory flow mini-loop apparatus was set up to measure the induction time of methane hydrate formation. The induction time is predicted using developed Kashchiev and Firoozabadi model and modified model of Natarajan for a flow loop system. Furthermore, the effects of volumetric flow rate of the fluid on the induction time were investigated. The results of the models were compared with experimental data. They show that the induction time of hydrate formation in the presence of THF is very short at high pressure and high volumetric flow rate of the fluid. It decreases with increasing pressure and liquid volumetric flow rate. It is also shown that the modified Natarajan model is more accurate than the Kashchiev and Firoozabadi ones in prediction of the induction time.

  18. The Contributions of Human Mini-Intestines to the Study of Intestinal Physiology and Pathophysiology.

    Science.gov (United States)

    Yu, Huimin; Hasan, Nesrin M; In, Julie G; Estes, Mary K; Kovbasnjuk, Olga; Zachos, Nicholas C; Donowitz, Mark

    2017-02-10

    The lack of accessibility to normal and diseased human intestine and the inability to separate the different functional compartments of the intestine even when tissue could be obtained have held back the understanding of human intestinal physiology. Clevers and his associates identified intestinal stem cells and established conditions to grow "mini-intestines" ex vivo in differentiated and undifferentiated conditions. This pioneering work has made a new model of the human intestine available and has begun making contributions to the understanding of human intestinal transport in normal physiologic conditions and the pathophysiology of intestinal diseases. However, this model is reductionist and lacks many of the complexities of normal intestine. Consequently, it is not yet possible to predict how great the advances using this model will be for understanding human physiology and pathophysiology, nor how the model will be modified to include multiple other intestinal cell types and physical forces necessary to more closely approximate normal intestine. This review describes recent studies using mini-intestines, which have readdressed previously established models of normal intestinal transport physiology and newly examined intestinal pathophysiology. The emphasis is on studies with human enteroids grown either as three-dimensional spheroids or two-dimensional monolayers. In addition, comments are provided on mouse studies in cases when human studies have not yet been described.

  19. Pursuit of food versus pursuit of information in a Markovian perception-action loop model of foraging.

    Science.gov (United States)

    Agarwala, Edward K; Chiel, Hillel J; Thomas, Peter J

    2012-07-07

    Efficient coding, redundancy reduction, and other information theoretic optimization principles have successfully explained the organization of many biological phenomena, from the physiology of sensory receptive fields to the variability of certain DNA sequence ensembles. Here we examine the hypothesis that behavioral strategies that are optimal for survival must necessarily involve efficient information processing, and ask whether there can be circumstances in which deliberately sacrificing some information can lead to higher utility? To this end, we present an analytically tractable model for a particular instance of a perception-action loop: a creature searching for a randomly moving food source confined to a 1D ring world. The model incorporates the statistical structure of the creature's world, the effects of the creature's actions on that structure, and the creature's strategic decision process. The underlying model takes the form of a Markov process on an infinite dimensional state space. To analyze it we construct an exact coarse graining that reduces the model to a Markov process on a finite number of "information states". This mathematical technique allows us to make quantitative comparisons between the performance of an information-theoretically optimal strategy with other candidate search strategies on a food gathering task. We find that 1. Information optimal search does not necessarily optimize utility (expected food gain). 2. The rank ordering of search strategies by information performance does not predict their ordering by expected food obtained. 3. The relative advantage of different strategies depends on the statistical structure of the environment, in particular the variability of motion of the source. We conclude that there is no simple relationship between information and utility. Even in the absence of information processing costs or bandwidth constraints, behavioral optimality does not imply information efficiency, nor is there a simple

  20. A prototype framework for models of socio-hydrology: identification of key feedback loops and parameterisation approach

    Science.gov (United States)

    Elshafei, Y.; Sivapalan, M.; Tonts, M.; Hipsey, M. R.

    2014-06-01

    It is increasingly acknowledged that, in order to sustainably manage global freshwater resources, it is critical that we better understand the nature of human-hydrology interactions at the broader catchment system scale. Yet to date, a generic conceptual framework for building models of catchment systems that include adequate representation of socioeconomic systems - and the dynamic feedbacks between human and natural systems - has remained elusive. In an attempt to work towards such a model, this paper outlines a generic framework for models of socio-hydrology applicable to agricultural catchments, made up of six key components that combine to form the coupled system dynamics: namely, catchment hydrology, population, economics, environment, socioeconomic sensitivity and collective response. The conceptual framework posits two novel constructs: (i) a composite socioeconomic driving variable, termed the Community Sensitivity state variable, which seeks to capture the perceived level of threat to a community's quality of life, and acts as a key link tying together one of the fundamental feedback loops of the coupled system, and (ii) a Behavioural Response variable as the observable feedback mechanism, which reflects land and water management decisions relevant to the hydrological context. The framework makes a further contribution through the introduction of three macro-scale parameters that enable it to normalise for differences in climate, socioeconomic and political gradients across study sites. In this way, the framework provides for both macro-scale contextual parameters, which allow for comparative studies to be undertaken, and catchment-specific conditions, by way of tailored "closure relationships", in order to ensure that site-specific and application-specific contexts of socio-hydrologic problems can be accommodated. To demonstrate how such a framework would be applied, two socio-hydrological case studies, taken from the Australian experience, are presented