Academic literature on the topic 'Local feedback regulation'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Local feedback regulation.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Local feedback regulation"
1
Taghvafard, Hadi, Alexander Medvedev, Anton V. Proskurnikov, and Ming Cao. "Impulsive model of endocrine regulation with a local continuous feedback." Mathematical Biosciences 310 (April 2019): 128–35. http://dx.doi.org/10.1016/j.mbs.2019.02.006.
Full text
2
Takeda, S., C. Gapper, H. Kaya, E. Bell, K. Kuchitsu, and L. Dolan. "Local Positive Feedback Regulation Determines Cell Shape in Root Hair Cells." Science 319, no. 5867 (February 29, 2008): 1241–44. http://dx.doi.org/10.1126/science.1152505.
Full text
3
Miao, Zhixin, and Lingling Fan. "Achieving Economic Operation and Secondary Frequency Regulation Simultaneously Through Local Feedback Control." IEEE Transactions on Power Systems 32, no. 1 (January 2017): 85–93. http://dx.doi.org/10.1109/tpwrs.2016.2544847.
Full text
4
Taghvafard, Hadi, Anton V. Proskurnikov, and Ming Cao. "Local and global analysis of endocrine regulation as a non-cyclic feedback system." Automatica 91 (May 2018): 190–96. http://dx.doi.org/10.1016/j.automatica.2018.01.035.
Full text
5
Walker, J. J., F. Spiga, R. Gupta, Z. Zhao, S. L. Lightman, and J. R. Terry. "Rapid intra-adrenal feedback regulation of glucocorticoid synthesis." Journal of The Royal Society Interface 12, no. 102 (January 2015): 20140875. http://dx.doi.org/10.1098/rsif.2014.0875.
Full textAbstract:
The hypothalamic–pituitary–adrenal axis is a vital neuroendocrine system that regulates the secretion of glucocorticoid hormones from the adrenal glands. This system is characterized by a dynamic ultradian hormonal oscillation, and in addition is highly responsive to stressful stimuli. We have recently shown that a primary mechanism generating this ultradian rhythm is a systems-level interaction where adrenocorticotrophin hormone (ACTH) released from the pituitary stimulates the secretion of adrenal glucocorticoids, which in turn feedback at the level of the pituitary to rapidly inhibit ACTH secretion. In this study, we combine experimental physiology and mathematical modelling to investigate intra-adrenal mechanisms regulating glucocorticoid synthesis. Our modelling results suggest that glucocorticoids can inhibit their own synthesis through a very rapid (within minutes), presumably non-genomic, intra-adrenal pathway. We present further evidence for the existence of a short time delay in this intra-adrenal inhibition, and also that at the initiation of each ACTH stimulus, this local feedback mechanism is rapidly antagonized, presumably via activation of the specific ACTH receptor (MC2R) signalling pathway. This mechanism of intra-adrenal inhibition enables the gland to rapidly release glucocorticoids while at the same time preventing uncontrolled release of glucocorticoids in response to large surges in ACTH associated with stress.
6
Song, Yohan, Anping Xia, Hee Yoon Lee, Rosalie Wang, Anthony J. Ricci, and John S. Oghalai. "Activity-dependent regulation of prestin expression in mouse outer hair cells." Journal of Neurophysiology 113, no. 10 (June 2015): 3531–42. http://dx.doi.org/10.1152/jn.00869.2014.
Full textAbstract:
Prestin is a membrane protein necessary for outer hair cell (OHC) electromotility and normal hearing. Its regulatory mechanisms are unknown. Several mouse models of hearing loss demonstrate increased prestin, inspiring us to investigate how hearing loss might feedback onto OHCs. To test whether centrally mediated feedback regulates prestin, we developed a novel model of inner hair cell loss. Injection of diphtheria toxin (DT) into adult CBA mice produced significant loss of inner hair cells without affecting OHCs. Thus, DT-injected mice were deaf because they had no afferent auditory input despite OHCs continuing to receive normal auditory mechanical stimulation and having normal function. Patch-clamp experiments demonstrated no change in OHC prestin, indicating that loss of information transfer centrally did not alter prestin expression. To test whether local mechanical feedback regulates prestin, we used TectaC1509G mice, where the tectorial membrane is malformed and only some OHCs are stimulated. OHCs connected to the tectorial membrane had normal prestin levels, whereas OHCs not connected to the tectorial membrane had elevated prestin levels, supporting an activity-dependent model. To test whether the endocochlear potential was necessary for prestin regulation, we studied TectaC1509G mice at different developmental ages. OHCs not connected to the tectorial membrane had lower than normal prestin levels before the onset of the endocochlear potential and higher than normal prestin levels after the onset of the endocochlear potential. Taken together, these data indicate that OHC prestin levels are regulated through local feedback that requires mechanoelectrical transduction currents. This adaptation may serve to compensate for variations in the local mechanical environment.
7
Wilde, C. J., C. V. P. Addey, L. M. Boddy, and M. Peaker. "Autocrine regulation of milk secretion by a protein in milk." Biochemical Journal 305, no. 1 (January 1, 1995): 51–58. http://dx.doi.org/10.1042/bj3050051.
Full textAbstract:
Frequency or completeness of milk removal from the lactating mammary gland regulates the rate of milk secretion by a mechanism which is local, chemical and inhibitory in nature. Screening of goat's milk proteins in rabbit mammary explant cultures identified a single whey protein of M(r) 7600 able to inhibit synthesis of milk constituents. The active whey protein, which we term FIL (Feedback inhibitor of Lactation), also decreased milk secretion temporarily when introduced into a mammary gland of lactating goats. FIL was synthesized by primary cultures of goat mammary epithelial cells, and was secreted vectorially together with other milk proteins. N-terminal amino acid sequencing indicated that it is a hitherto unknown protein. The evidence indicates that local regulation of milk secretion by milk removal is through autocrine feedback inhibition by this milk protein.
8
Abelew, Thomas A., Melissa D. Miller, Timothy C. Cope, and T. Richard Nichols. "Local Loss of Proprioception Results in Disruption of Interjoint Coordination During Locomotion in the Cat." Journal of Neurophysiology 84, no. 5 (November 1, 2000): 2709–14. http://dx.doi.org/10.1152/jn.2000.84.5.2709.
Full textAbstract:
To investigate the role of localized, proprioceptive feedback in the regulation of interjoint coordination during locomotion, we substantially attenuated neural feedback from the triceps surae muscles in one hindlimb in each of four cats using the method of self-reinnervation. After allowing the recovery of motor innervation, the animals were filmed during level and ramp walking. Deficits were small or undetectable during walking on the level surface or up the ramp, behaviors that require a large range of forces in the triceps surae muscles. During walking down the ramp, when the triceps surae muscles normally undergo active lengthening, the ankle joint underwent a large yield and the coordination between ankle and knee was disrupted. The correlation of the deficit with the direction of length change and not muscle force suggested that a loss of feedback from muscle spindle receptors was primarily responsible for the deficit. These results indicate an important role for the stretch reflex and stiffness regulation during locomotion.
9
Stewart, G. M., C. V. P. Addey, C. H. Knight, and C. J. Wilde. "AUTOCRINE REGULATION OF CASEIN TURNOVER IN GOAT MAMMARY EXPLANTS." Journal of Endocrinology 118, no. 1 (July 1988): R1—R3. http://dx.doi.org/10.1677/joe.0.118r001.
Full textAbstract:
ABSTRACT Local feedback control of milk protein secretion was investigated in goat mammary explants by measuring degradation of newly synthesized casein in the presence of a goat milk whey fraction. Reduced net synthesis of [3H]casein in the presence of the milk fraction was due, at least in part, to its degradation during secretion, suggesting that this process is under autocrine regulation.
10
Emek, Sevcan, Vedat Evren, and Şebnem Bora. "Simulation of glucose regulating mechanism with an agent-based software engineering tool." An International Journal of Optimization and Control: Theories & Applications (IJOCTA) 9, no. 3 (March 20, 2019): 15–20. http://dx.doi.org/10.11121/ijocta.01.2019.00685.
Full textAbstract:
This study provides a detailed explanation of a regulating mechanism of the blood glucose levels by an agent-based software engineering tool. Repast Simphony which is used in implementation of this study is an agent-based software engineering tool based on the object-oriented programming using Java language. Agent-based modeling and simulation is a computational methodology for simulating and exploring phenomena that includes a large set of active components represented by agents. The agents are main components situated in space and time of agent-based simulation environment. In this study, we present hormonal regulation of blood glucose levels by our improved agent-based control mechanism. Hormonal regulation of blood glucose levels is an important process to maintain homeostasis inside the human body. We offer a negative feedback control mechanism with agent-based modeling approach to regulate the secretion of insulin hormone which is responsible for increasing the blood glucose levels. The negative feedback control mechanism run by three main agents that interact with each other to perform their local actions in the simulation environment. The result of this study shows the local behavior of the agents in the negative feedback loop and illustrates how to balance the blood glucose levels. Finally, this study which is thought a potential implementation of agent-based modeling and simulation may contribute to the exploration of other homeostatic control systems inside the human body.
Dissertations / Theses on the topic "Local feedback regulation"
1
Thomson, Susmita. "Local feedback regulation of salt & water transport across pumping epithelia : experimental & mathematical investigations in the isolated abdominal skin of Bufo marinus." University of Western Australia. Dept. of Physiology, 2003. http://theses.library.uwa.edu.au/adt-WU2003.0022.
Full textAbstract:
[Truncated abstract] This study describes the results of a four and a half year investigation examining local regulation of ion transport through pumping epithelial cells. The study focussed on the standard isolated toad skin preparation, made famous by Hans Ussing. Originally, the objective was to perform some simple manipulations on the isolated toad skin, a standard and well-tested epithelial layer, which, according to the literature, was a well-behaved and stable preparation. The purpose of doing these toad skin experiments was to gain familiarity with the experimental techniques, such as measuring the open-circuit voltage (Voc) and the short-circuit current (Isc) across an epithelium. In the process, the experimental information that was obtained was to assist in the development and refinement of a mathematical model of a single pumping epithelial cell . . . Finally, it should be emphasised the toad skin was a convenient tissue model for exploring more general issues such as: (i) how pumping epithelial cells may adjust to changes in the extracellular environment by locally regulating their membrane conductances; (2) how the topology of a cell can influence its function (i.e. the topology can determine whether a cell is optimised for salt transport or water transport). (3) how different cells, with different functions, may be positioned in apposition in a pumping epithelial tissue so that gradients generated by one cell type can be utilised by another. From a broader perspective, it is likely that such issues are also applicable to other pumping epithelia, and ultimately, may assist in understanding how these epithelia function.
2
Thomson, Susmita. "Local feedback regulation of salt & water transport across pumping epithelia : experimental & mathematical investigations in the isolated abdominal skin of Bufo marinus /." Connect to this title, 2002. http://theses.library.uwa.edu.au/adt-WU2003.0022.
Full text
3
Roberts, Thomas Maximillian. "Local Regulation of Interchange Turbulence in a Dipole-Confined Plasma Torus using Current-Injection Feedback." Thesis, 2015. https://doi.org/10.7916/D8GT5M4S.
Full textAbstract:
Turbulence in plasma confined by a magnetic dipole is dominated by interchange fluctuations with complex dynamics and short spatial coherence. We report the first use of local current-collection feedback to modify, amplify, and suppress these fluctuations. The spatial extent of turbulence regulation is limited to a correlation length near the collector. Changing the gain and phase of collection results in power either extracted from or injected into the turbulence. This mechanism is analogous to the magnetospheric-ionospheric coupling by field-aligned currents. The measured plasma response shows some agreement with calculations of the linear response of global interchange-like MHD and entropy modes to current-collection feedback.
Books on the topic "Local feedback regulation"
1
Browning, Birch P. How Students Acquire Musical Understanding. Oxford University Press, 2017. http://dx.doi.org/10.1093/acprof:oso/9780199928200.003.0007.
Full textAbstract:
The chapter describes how initial musical learning occurs as infants are exposed to motherese, or infant-directed speech, and react to aural stimuli by encoding information. The aural-oral feedback loop by which babies learn sounds is illustrated. The chapter also covers children’s acquisition of an understanding of local musical culture through acculturation. Subsequent formal instruction enables students to perceive, think about, perform, and create music. The developmental process for understanding music notation is shown to be remarkably similar to thatfor learning oral and written language. The outcomes of formal instruction are covered, including the ability to understand music from a variety of perspectives, which enables the rapid acquisition of new repertoire. Musical understanding is described as the synthesis of and interaction between musical knowledge and musical skill, with the goal of self-regulation in learning
Book chapters on the topic "Local feedback regulation"
1
Das Sharma, Kaushik. "A Comparison among Multi-Agent Stochastic Optimization Algorithms for State Feedback Regulator Design of a Twin Rotor MIMO System." In Handbook of Research on Natural Computing for Optimization Problems, 409–48. IGI Global, 2016. http://dx.doi.org/10.4018/978-1-5225-0058-2.ch018.
Full textAbstract:
Multi-agent optimization or population based search techniques are increasingly become popular compared to its single-agent counterpart. The single-agent gradient based search algorithms are very prone to be trapped in local optima and also the computational cost is higher. Multi-Agent Stochastic Optimization (MASO) algorithms are much powerful to overcome most of the drawbacks. This chapter presents a comparison of five MASO algorithms, namely genetic algorithm, particle swarm optimization, differential evolution, harmony search algorithm, and gravitational search algorithm. These MASO algorithms are utilized here to design the state feedback regulator for a Twin Rotor MIMO System (TRMS). TRMS is a multi-modal process and the design of its state feedback regulator is quite difficult using conventional methods available. MASO algorithms are typically suitable for such complex process optimizations. The performances of different MASO algorithms are presented and discussed in light of designing the state regulator for TRMS.
2
Rodríguez, Rocío Andrea, Daniel Alberto Giulianelli, Pablo Martín Vera, Artemisa Trigueros, and Isabel Beatriz Marko. "E-Governance Survey on Municipalities Web Sites." In Quality and Communicability for Interactive Hypermedia Systems, 142–60. IGI Global, 2010. http://dx.doi.org/10.4018/978-1-61520-763-3.ch007.
Full textAbstract:
E-Governance aims to provide high quality of government for citizens. It covers services, information delivery and interactive community / government communication. This goal can be achieved by adopting the ICT (Information and Communication Technologies) tools in the government web site´s design and contents. This communication channel allows a redefinition of the traditional role played by each one of the actors of the relation. The government as provider of: services, information, transparency and interactive communication. The citizens acting as active subjects with their government, using services, receiving information, controlling the government´s decisions and returning feedback to them. This feedback includes opinions, complaints and suggestions delivered by the web sites’ interactive tools. This research surveyed if the implementation of ICT tools regarding national and international norms and regulations for web sites development and content, increases the fulfillment of the key concepts of e-governance: e-democracy, e-services, e-transparency and active and passive communication. 30 local government web sites of Argentine were analyzed by checking if they implemented the ICT tools expressed by the seven basic concepts of design and contents: Navigability, Veracity, Friendliness, Functionality, Accessibility, Usability and Information through 152 weighed aspects that fulfill these seven concepts. The analysis of the score obtained by the web sites showed their e-governance development level and what aspects they have to implement to improve e-governance quality.
Conference papers on the topic "Local feedback regulation"
1
Hudon, N., and M. Guay. "Local dissipative Hamiltonian realization by feedback regulation." In 2010 49th IEEE Conference on Decision and Control (CDC). IEEE, 2010. http://dx.doi.org/10.1109/cdc.2010.5717493.
Full text
2
Fan, Sha, Chao Sun, Chunxi Yang, and Bo Ye. "Fast distributed Kalman-Consensus filtering algorithm with local feedback regulation." In 2015 IEEE International Conference on Information and Automation (ICIA). IEEE, 2015. http://dx.doi.org/10.1109/icinfa.2015.7279678.
Full text
3
Zhusubaliyev, Zhanybai T., Alexander Medvedev, and Anton V. Proskurnikov. "Impulsive Goodwin’s Oscillator Model of Endocrine Regulation: Local Feedback Leads to Multistability." In 2021 7th International Conference on Event-Based Control, Communication, and Signal Processing (EBCCSP). IEEE, 2021. http://dx.doi.org/10.1109/ebccsp53293.2021.9502366.
Full text
4
Marti´nez, Rube´n, Israel Mazaira, and Vicente Feliu. "Control of First Order Systems With Bounded Input by Asymptotic Output Tracking With Fractional Regulators." In ASME 2007 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/detc2007-34557.
Full textAbstract:
In this paper, the control of first order systems by applying fractional regulators in the time domain with bounded input is presented. The design of the proposed fractional regulator, is based in the local asymptotic output tracking of linear systems with bounded control input by linear dynamic state feedback and the reduction of the system time response by the expansion of integer-order models to rational-order one.
5
Doucet, M., P. Faye, Ch Faignet, R. Babut, M. Landrieu, F. Marvaud, and G. Romanet. "FCC-NG: The AREVA Safe Fresh Fuel Shipping Cask to Deliver the Future EPR™ Reactors." In 18th International Conference on Nuclear Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/icone18-29436.
Full textAbstract:
AREVA as a worldwide PWR fuel provider has to have a fleet of fresh UO2 shipping casks being agreed within a lot of countries and to accommodate foreseen EPR™ Nuclear Power Plants fuel buildings. To reach this target the AREVA NP Fuel Sector together with TN International (a subsidiary of AREVA NC) decided to develop an up to date shipping cask gathering experience feedback of the today fleet and an improved safety allowing the design to comply with international regulations (NRC and IAEA) and other local foreign Safety Authorities requirements. Based on pre design features a safety case was set up to highlight safety margins. Criticality hypothetical accidental assumptions were defined: • Preferential flooding, • Fuel rod array expansion (so called “bird caging” effect), • Fuel sliding, • Neutron absorber penalty, • …. The French criticality code package CRISTAL is used to check several configurations reactivity and derived safety margins. The CRISTAL code package relies on a wide validation process helping defining uncertainties as required by regulations in force. The shipping cask, containing two fuel assemblies, is designed to maximize fuel isolation inside the cask and with neighboring ones even for large array configuration cases. Few and proven industrial products are used: • Stainless steel for the structural frame, • Balsa wood for impact limiters, • BORA® resin as neutron absorber. The cask is designed to handle mainly the EPR™ fuel assembly type and may be extended to other contents such as APWR fuel assembly type. After a brief presentation of the computer codes and the description of the shipping cask, the CRISTAL calculation results as well as the applied uncertainties will be discussed.
6
Badawy, Tamer, and Naeim Henein. "3D CFD Modeling and Validation of Ion Current Sensor in a Gen-Set Diesel Engine Using Chemical Kinetic Mechanism." In ASME 2016 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/icef2016-9375.
Full textAbstract:
The control of the combustion process is becoming a necessity for diesel engines in order to meet the upcoming stringent emission regulations. Ion current sensing technology has the potential to provide real-time feedback of the combustion process while using a fairly inexpensive sensor. 3D computational fluid dynamics (CFD) cycle simulation is becoming more complementary in understanding the complex combustion process in diesel engines. In this paper, a CFD study is focused on investigating the characteristics of the ion current signal produced during the combustion process of a Gen-set turbocharged diesel engine. Multiple virtual ion sensing probes are defined in different locations inside the combustion chamber to understand the influence of sensor location on signal characteristics. The n-heptane reaction mechanism and NO mechanism, combined with an ionization mechanism developed at WSU with 11 species, are used in the model to predict the chemical kinetics of combustion and the mole fraction of ionized species produced during combustion. Since the charge in diesel engines is heterogeneous and due to the sensing nature of the ion sensor, this paper explores the effect of sensor sensing diameter and its protrusion depth inside the combustion chamber on the ion current signal development. The simulation is validated by comparing in-cylinder pressure traces, the rate of heat release, and the ion current signal. Further, the model results are validated under different engine loads and injection pressures. This study utilizes the ionization mechanism to give further understanding of the complex formation of ionization species and their amplitudes, particularly at local sensing locations. This can be very vital to identify the potentials of using the ion current sensing and highlight its viability in feedback closed loop combustion control.
7
Brown, Jason A., Robert A. Osterrieder, Robert J. Lutz, Maurice Dingler, and Lewis A. Ward. "Westinghouse Owners Group Risk-Informed Regulation Efforts: Options 2 and 3." In 10th International Conference on Nuclear Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/icone10-22597.
Full textAbstract:
The U.S. Nuclear Regulatory Commission (NRC) has initiated efforts to incorporate risk-informed methods to redefine the scope of the existing 10 CFR 50 regulations (Option 2) and to change the technical requirements of the regulations (Option 3). The overall objectives of these efforts are to enhance plant safety, provide a framework for risk-informed regulations, add flexibility to plant operations, and reduce regulatory burden. The Westinghouse Owners Group (WOG) has a variety of active programs in the risk-informed area, including a program in the Option 2 and Option 3 areas. These two programs will be summarized including the benefits and the technical approach. The purpose of Option 2 is to make changes to the overall scope of structures, systems and components (SSCs) covered by 10 CFR 50 requiring special treatment by formulating new risk-informed safety classification categories that are linked to current definitions of safety-related and important-to-safety. This initiative would permit possible changes to the current special treatment requirements based on risk insights. The Nuclear Energy Institute (NEI) has developed an Option 2 implementation guideline (NEI 00-04 Draft Revision B). The WOG has initiated a program to validate the NEI guideline and to provide an initial cost-benefit assessment of the revised categorization and treatment under Option 2 via trial application to two systems at both Surry Unit 1 and Wolf Creek. The WOG Option 2 program includes consideration of all of the components in the selected systems, regardless of whether or not they are modeled in the respective plant probabilistic risk assessment (PRA) studies. As a result, quantitative risk measures are not available for many of the components being considered. In this case, the WOG program will provide valuable input to the NEI guideline. Additionally, the WOG program extends the use of both of the dominant methodologies for risk-informed ISI (RI-ISI) to address repair and replacement activities of pressure-retaining items per Code Cases under development within ASME. Therefore, feedback is provided on the consideration of passive components for extending both the WOG and Electric Power Research Institute (EPRI) RI-ISI methodologies for piping to all pressure-retaining items. In the Option 3 area, the WOG Large Break Loss-of-Coolant Accident (LBLOCA) Redefinition program is a risk-informed approach to improve select regulations (10 CFR 50.46, Appendix A, and Appendix K) such that the plant licensing basis is focused on LOCA break sizes up to a new maximum size. The new maximum break size will replace the existing requirement to consider break sizes up to and including double ended breaks of the largest primary system piping. Plants will retain the capability to mitigate a break of the largest primary system piping as evaluated using realistic success criteria and assumptions. The WOG is also providing input to the development of a risk-informed 10 CFR 50.44 based on insights from the WOG Severe Accident Management Guidance and plant-specific PRA studies.
8
Libby, Peter, Stephen J. C. Warner, and Louis K. Birinyi. "THE VESSEL WALL AS A SOURCE OF VASORHGOLATORY AND IMMDNOSTIMOLATORY CYTOKINES." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643982.
Full textAbstract:
The cytokines Interleukin-1 (IL-1) and Tumor Necrosis Factor (TNF, also known as cachectin) exhibit multiple effects on circulating blood cells and cells of the blood vessel wall. For example, these mediators elicit a coordinated Drogram of functions of endothelial cells (EC) that promotes blood coagulation and thrombosis, and lead to clot stabilization. Furthermore, IL-1 and TNF promote adherence to vascular endothelium of leukocytes of many classes.Thus, these cytokines are likely to be involved in signaling the pathologic changes in blood vessels that characterize a number of inflammatory or infectious processes. These two cytokines were originally isolated frcm activated human mononuclear phagocytes, hence their comnon designation as monokines and the terminology "interleukin". However, recent findings have broadened this concept considerably. It is now clear that many cell types can produce IL-1-1ike activity.Several groups showed that human vascular EC can secrete material that stimulates proliferation of thymocytes incubated with suboptima1 doses of the mitogenic lectin phytohemagglutinin, a typical acitivty of IL-1 (thymocyte costimulation).Two related but distinct genes cloned frcm human peripheral blood monocytes encode IL-1 molecules. In human blood monocytes stimulated with bacterial lioopolysaccharide (LPS) IL-1 beta (pi ∼ 7) is the major form expressed while IL-1 alpha (pi ∼ 5) is the less abundant species secreted by human monocytes under these conditions. We found that EC and smooth muscle cells (SMC) isolated from adult human vessels can express these same IL-1 genes. LPS, a standard stimulus to IL-1 secretion in the monocyte, caused accumulation of IL-1 beta mRNA in both vascular cell types. Endothelial cells frcm adult human vessels also contained IL-1 alpha mRNA when treated with LPS in the presence of cycloheximide and LPS-stimulated smooth muscle cells contained RNA that hybridized with an IL-1 alpha cDNA probe as well. Although both vascular cell types can transcribe these IL-1 genes, the time course of this response differs. LPS induced IL-1 beta mRNA production by SMC maximally at 4-6 hr., whereas maximal IL-1 induction by LPS in EC occured 1 day after initiation of the exposure. Actinanycin D (1 ug/ml) blocked 3H-uridine incorporation into macromolecules by > 95% in both EC & SMC, and prevented the LPS-induced increases in IL-1 mRNA levels in these cells. This result suggests that this potentially injurious stimulus causes IL-1 mRNA accumulation by an increase in rates of transcription. These LPS-induced increases in IL-1 mRNA levels corresponded to production of biologically active IL-1 determined as thymocyte costimulation activity. Interestingly, gel filtration experiments revealed a molecular weight of around 22kD for both SMC and EC-derived IL-1 secreted into culture medium in response to LPS. This molecular weight contrasts with the 17 kD species which is the fully processed product secreted frcm activated human monocytes. A possible explanation for this disparity is that the vascular cells secrete a partially processed intermediate form of mature IL-1. Other stimuli for IL-1 mRNA accumulation and secretion of biological activity include TNF and IL-1 itself. Recombinant human INF (≥ 10 ng/ml) increased IL-1 beta mRNA levels in EC & SMC, and caused the EC & SMC to release IL-1-1 ike thymocyte costimulation activity. Of interest is the recent observation that IL-1 itself can stimulate expression of IL-rl genes in vascular wall cells. Both IL-1 aloha and beta can increase IL-1 beta mRNA content in EC & SMC. Hris observation was confirmed with homogenous IL-1 prepared by recombinant DNA technologies (rIL-1). These findings raise the possibility of a novel positive feedback loop in vascular pathophysiology. We also found that rIL-1 alpha or beta also induced the production of prostaglandin E2 (PGE2) by both vascular SMC & EC. This prostanoid, induced by IL-1, inhibits thymocyte _ proliferation. Thus, IL-1 not only induced its own expression but increased production of this immunosuppressive prostanoid. This mechanism provides a potential negative control loop in regulation of the local immune response in blood vessels. Vie conclude that these cells of the blood vessel wall are a source of the potent vasoregulatory and immune mediators IL-1 alpha and beta. Since IL-1 influences the thrombotic, hemostatic, and fibrinolytic functions of endothelium, as well as other responses to acute injury, our findings suggest novel local control mechanisms that may be important in a variety of pathologic states.
9
Ja´nosine´ Bi´ro´, A´gnes, Sa´ndor Ra´tkai, Ma´rton Osztheimer, Katalin Baumann-ne´ Tanits, and Sa´ndor Baranya. "Development of Component Specific Ageing Management Programmes for Mechanical Components at the NPP Paks." In ASME 2009 Pressure Vessels and Piping Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/pvp2009-77504.
Full textAbstract:
The plant’s current ageing management practice is based on designer’s specifications and the more than 20 years of operation and maintenance experience. This practice meets the established rules and requirements in depth. In accordance with local regulations for long term operation the implementation of a comprehensive ageing management system for a defined scope of nuclear (safety classes 1–3+) components is required. As part of the comprehensive system, type ageing management programmes (TAMP) are developed, from which component specific programmes (SAMP) shall be developed and executed for the passive components of the concerned scope. This presentation summarizes the specific ageing management programmes of the WWER main components (reactor pressure vessel, steam generator, pressurizer, main coolant pump, main circulation pipeline, main gate valve) and of some other mechanical equipment (ECCS heat-exchangers, main steamline valves, steam generator drain expander tanks and emergency feedwater pumps). The development of the SAMPs is based on the TAMPs that describe the degradation processes (low-cycle fatigue, thermal ageing, irradiation damage, stress corrosion, boric acid corrosion, wear, local corrosion, irradiation assisted stress corrosion, loosening of threaded fasteners, swelling, high-cycle fatigue, general corrosion, thermal stratification fatigue, erosion, erosion-corrosion, water hammer, ground water corrosion, microbiological corrosion, deposition). The format and content of the SAMP comply with the domestic regulatory system and essentially follow the attributes of the US NRC’s 10 element ageing management programme (scope, prevention, parameters to be inspected, detection, monitoring-trending, acceptance criteria, corrective actions, feedback, administrative control, utilization of operating experience). During programme development, the review and, based on specific aspects, the examination of compliance of each established programme (technical review plan, ISI programme, ISI acceptance standards, maintenance instructions, water chemistry programmes, operational manuals, other inspection programmes etc.) dealing with the given component and affecting its ageing management were carried out, also taking account of the Aging Management (AM) review reports produced as part of the service life extension project. On the one hand the evaluation of the SAMP confirmed the effectiveness of the programmes currently applied, from ageing management aspects, and on the other hand, the recommended developments and enhancements help establish and strengthen the Comprehensive Ageing Management system.
10
Blower, Christopher J., and Adam M. Wickenheiser. "The Variations in Active Panel Location and Number for a Bioinspired Aircraft Gust Alleviation System." In ASME 2012 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/smasis2012-7994.
Full textAbstract:
This paper presents the development of a biomimetic closed-loop flight controller that integrates gust alleviation and flight control into a single distributed system of feather-like panels over the upper and lower surfaces. This bio-inspired gust alleviation system (GAS) mimics the techniques used by birds to respond to turbulent and gusting airflow. The GAS design replicates the profile of a bird’s wing through the installation of feather-like panels across the upper and lower surfaces of the airfoil, and replacement of the trailing-edge flaps. While flying through gusts, the flight controller uses a linear quadratic regulator to perform continuous adjustments to the local states through active deflection of electromechanical feathers. This system consequently offers a wide range of flap configurations that enable the vehicle to perform gust response maneuvers unachievable by standard aircraft. The GAS is developed using a 2D adaptive panel method that enables analysis of the airfoil’s aerodynamic performance during all flap configurations. The airfoil’s dynamic model is simulated to calculate the disturbances incurred during gusting flows. The flight controller tracks the vehicles velocity, angle of attack and position, and continuously performs adjustment to the orientation of each flap to induce the corrective responses to inbound gusts. The replacement of standard single trailing edge profile with the integration of a dual trailing edge (DTE) configuration offers a reduction of the aircraft’s deviation from the target flight path through the introduction of aero-braking during strong longitudinal gusts. The introduction of 6 additional surface flaps offers new flap configurations capable of minimizing the disturbances in the aircraft’s global states. Non-linear and linear dynamic models of the 8-flap GAS are compared to a traditional single control surface baseline wing and the DTE configuration. The feedback loops synthesized depend on the inertial changes of the global states; however, variations in flap configuration are compared. The integration of an 8-flap GAS provides enhancements to maneuverability and stability in turbulent intensive environments.