Interaction between EGFR and EphA2

DEFF Research Database (Denmark)

Larsen, Alice Bjerregaard

2010-01-01

Enhanced or altered epidermal growth factor receptor (EGFR) activity has been reported in many human cancers and several molecular targeting therapies has been developed. However, despite intense research, therapies targeting EGFR have shown conflicting results in clinical studies, indicating...... the involvement of other important molecular players. Several different EGFR mutations have been reported in cancer, one of which is the cancer specific type III EGFR deletion mutant (EGFRvIII, de2-7EGFR, ΔEGFR). In a global search for EGFR and EGFRvIII regulated genes we identified the receptor tyrosine kinase...... (RTK) EphA2. EphA2 belongs to the large Eph-receptor family, which has mainly been associated with neuronal development. More recently, expression of several Eph-receptors has been detected in many different cancer types. Elevated EphA2 expression has been reported in a broad range of human cancer...

Interaction between EGFR and EphA2

DEFF Research Database (Denmark)

Larsen, Alice Bjerregaard

2010-01-01

Enhanced or altered epidermal growth factor receptor (EGFR) activity has been reported in many human cancers and several molecular targeting therapies has been developed. However, despite intense research, therapies targeting EGFR have shown conflicting results in clinical studies, indicating...... the involvement of other important molecular players. Several different EGFR mutations have been reported in cancer, one of which is the cancer specific type III EGFR deletion mutant (EGFRvIII, de2-7EGFR, ¿EGFR). In a global search for EGFR and EGFRvIII regulated genes we identified the receptor tyrosine kinase...... (RTK) EphA2. EphA2 belongs to the large Eph-receptor family, which has mainly been associated with neuronal development. More recently, expression of several Eph-receptors has been detected in many different cancer types. Elevated EphA2 expression has been reported in a broad range of human cancer...

EphrinB1/EphB3b Coordinate Bidirectional Epithelial-Mesenchymal Interactions Controlling Liver Morphogenesis and Laterality

DEFF Research Database (Denmark)

Cayuso, Jordi; Dzementsei, Aliaksandr; Fischer, Johanna C

2016-01-01

Positioning organs in the body often requires the movement of multiple tissues, yet the molecular and cellular mechanisms coordinating such movements are largely unknown. Here, we show that bidirectional signaling between EphrinB1 and EphB3b coordinates the movements of the hepatic endoderm...... and adjacent lateral plate mesoderm (LPM), resulting in asymmetric positioning of the zebrafish liver. EphrinB1 in hepatoblasts regulates directional migration and mediates interactions with the LPM, where EphB3b controls polarity and movement of the LPM. EphB3b in the LPM concomitantly repels hepatoblasts...

EphA2 modulates radiosensitive of hepatocellular carcinoma cells via p38/mitogen-activated protein kinase-mediated signal pathways

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Qiao Jin

2015-10-01

Full Text Available This experiment was conducted to investigate the role of EPH receptor A2 (EphA2 in the modulation of radiosensitivity of hepatic cellular cancer (HCC cells and to determine whether p38/mitogen-activated protein kinase (p38MAPK signaling mediated EphA2 function in this respect. The protein expressions of EphA2 and phosphorylated p38MAPK were tested in HCC and normal hepatic tissues. In HCC 97H cells, EphA2 was overexpressed and knocked out by transfection with EphA2 expression vector and EphA2-ShRNA, respectively, prior to cell exposure to low-dose irradiation. Significantly upregulated EphA2 and phosphorylated p38MAPK were observed in HCC tissues, compared with those in normal hepatic tissues. Low-dose irradiation (1 Gy only caused minor damage to HCC 97H cells, as assessed by alterations in cell viability, apoptosis rate, and cell healing capacity (p = 0.072, p = 0.078, and p = 0.069 respectively. However, EphA2 knock-out in HCC 97H cells induced significant reduction in cell viability and cell healing capacity after these cells were subjected to low-dose irradiation. Apoptosis rate underwent dramatic increase (p < 0.01. By contrast, EphA2 overexpression in HCC 97H cells reversed these effects and enhanced cell colony formation rate, thus displaying remarkable attenuation of radiosensitivity of HCC 97H cells. Further, SB203580, a specific inhibitor of p38MAPK, was added to HCC 97H cells over-expressing EphA2. The effect of EphA2 overexpression on the radiosensitivity of HCC 97H cells was abrogated. Thus, the present study indicates that EphA2 have the ability to negatively regulate the radiosensitivity of HCC 97H cells, which mainly depends on 38MAPK-mediated signal pathways.

Design and synthesis of small molecule agonists of EphA2 receptor.

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Petty, Aaron; Idippily, Nethrie; Bobba, Viharika; Geldenhuys, Werner J; Zhong, Bo; Su, Bin; Wang, Bingcheng

2018-01-01

Ligand-independent activation of EphA2 receptor kinase promotes cancer metastasis and invasion. Activating EphA2 receptor tyrosine kinase with small molecule agonist is a novel strategy to treat EphA2 overexpressing cancer. In this study, we performed a lead optimization of a small molecule Doxazosin that was identified as an EphA2 receptor agonist. 33 new analogs were developed and evaluated; a structure-activity relationship was summarized based on the EphA2 activation of these derivatives. Two new derivative compounds 24 and 27 showed much improved activity compared to Doxazosin. Compound 24 possesses a bulky amide moiety, and compound 27 has a dimeric structure that is very different to the parental compound. Compound 27 with a twelve-carbon linker of the dimer activated the kinase and induced receptor internalization and cell death with the best potency. Another dimer with a six-carbon linker has significantly reduced potency compared to the dimer with a longer linker, suggesting that the length of the linker is critical for the activity of the dimeric agonist. To explore the receptor binding characteristics of the new molecules, we applied a docking study to examine how the small molecule binds to the EphA2 receptor. The results reveal that compounds 24 and 27 form more hydrogen bonds to EphA2 than Doxazosin, suggesting that they may have higher binding affinity to the receptor. Published by Elsevier Masson SAS.

Eph receptor interclass cooperation is required for the regulation of cell proliferation

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Jurek, Aleksandra; Genander, Maria [Department of Cell and Molecular Biology, Karolinska Institute, SE-171 77 Stockholm (Sweden); Kundu, Parag [Department of Microbiology, Tumor and Cell Biology, Karolinska Institute, SE-171 77 Stockholm (Sweden); Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551 (Singapore); Lee Kong Chian School of Medicine, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551 (Singapore); Catchpole, Timothy [Department of Developmental Biology, University of Texas Southwestern Medical Center, Dallas TX 75390 (United States); He, Xiao; Strååt, Klas; Sabelström, Hanna [Department of Cell and Molecular Biology, Karolinska Institute, SE-171 77 Stockholm (Sweden); Xu, Nan-Jie [Department of Developmental Biology, University of Texas Southwestern Medical Center, Dallas TX 75390 (United States); Pettersson, Sven [Department of Microbiology, Tumor and Cell Biology, Karolinska Institute, SE-171 77 Stockholm (Sweden); Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551 (Singapore); Lee Kong Chian School of Medicine, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551 (Singapore); The National Cancer Centre, Singapore General Hospital (Singapore); Henkemeyer, Mark [Department of Developmental Biology, University of Texas Southwestern Medical Center, Dallas TX 75390 (United States); Frisén, Jonas, E-mail: jonas.frisen@ki.se [Department of Cell and Molecular Biology, Karolinska Institute, SE-171 77 Stockholm (Sweden)

2016-10-15

Cancer often arises by the constitutive activation of mitogenic pathways by mutations in stem cells. Eph receptors are unusual in that although they regulate the proliferation of stem/progenitor cells in many adult organs, they typically fail to transform cells. Multiple ephrins and Eph receptors are often co-expressed and are thought to be redundant, but we here describe an unexpected dichotomy with two homologous ligands, ephrin-B1 and ephrin-B2, regulating specifically migration or proliferation in the intestinal stem cell niche. We demonstrate that the combined activity of two different coexpressed Eph receptors of the A and B class assembled into common signaling clusters in response to ephrin-B2 is required for mitogenic signaling. The requirement of two different Eph receptors to convey mitogenic signals identifies a new type of cooperation within this receptor family and helps explain why constitutive activation of a single receptor fails to transform cells. - Highlights: • We demonstrate that ephrin-B1 and ephrin-B2 have largely non-overlapping functions in the intestinal stem cell niche. • Ephrin-B1 regulates cell positioning and ephrin-B2 regulates cell proliferation in the intestinal stem cell niche. • EphA4/B2 receptor cooperation in response to ephrin-B2 binding is obligatory to convey mitogenic signals in the intestine. • EphA4 facilitates EphB2 phosphorylation in response to ephrin-B2 in SW480 adenocarcinoma cells. • Ephrin-B1 and ephrin-B2 induce phosphorylation and degradation of the EphB2 receptor with different kinetics.

Eph receptor interclass cooperation is required for the regulation of cell proliferation

International Nuclear Information System (INIS)

Jurek, Aleksandra; Genander, Maria; Kundu, Parag; Catchpole, Timothy; He, Xiao; Strååt, Klas; Sabelström, Hanna; Xu, Nan-Jie; Pettersson, Sven; Henkemeyer, Mark; Frisén, Jonas

2016-01-01

Cancer often arises by the constitutive activation of mitogenic pathways by mutations in stem cells. Eph receptors are unusual in that although they regulate the proliferation of stem/progenitor cells in many adult organs, they typically fail to transform cells. Multiple ephrins and Eph receptors are often co-expressed and are thought to be redundant, but we here describe an unexpected dichotomy with two homologous ligands, ephrin-B1 and ephrin-B2, regulating specifically migration or proliferation in the intestinal stem cell niche. We demonstrate that the combined activity of two different coexpressed Eph receptors of the A and B class assembled into common signaling clusters in response to ephrin-B2 is required for mitogenic signaling. The requirement of two different Eph receptors to convey mitogenic signals identifies a new type of cooperation within this receptor family and helps explain why constitutive activation of a single receptor fails to transform cells. - Highlights: • We demonstrate that ephrin-B1 and ephrin-B2 have largely non-overlapping functions in the intestinal stem cell niche. • Ephrin-B1 regulates cell positioning and ephrin-B2 regulates cell proliferation in the intestinal stem cell niche. • EphA4/B2 receptor cooperation in response to ephrin-B2 binding is obligatory to convey mitogenic signals in the intestine. • EphA4 facilitates EphB2 phosphorylation in response to ephrin-B2 in SW480 adenocarcinoma cells. • Ephrin-B1 and ephrin-B2 induce phosphorylation and degradation of the EphB2 receptor with different kinetics.

Evidence that the EphA2 receptor exacerbates ischemic brain injury.

Directory of Open Access Journals (Sweden)

John Thundyil

Full Text Available Ephrin (Eph signaling within the central nervous system is known to modulate axon guidance, synaptic plasticity, and to promote long-term potentiation. We investigated the potential involvement of EphA2 receptors in ischemic stroke-induced brain inflammation in a mouse model of focal stroke. Cerebral ischemia was induced in male C57Bl6/J wild-type (WT and EphA2-deficient (EphA2(-/- mice by middle cerebral artery occlusion (MCAO; 60 min, followed by reperfusion (24 or 72 h. Brain infarction was measured using triphenyltetrazolium chloride staining. Neurological deficit scores and brain infarct volumes were significantly less in EphA2(-/- mice compared with WT controls. This protection by EphA2 deletion was associated with a comparative decrease in brain edema, blood-brain barrier damage, MMP-9 expression and leukocyte infiltration, and higher expression levels of the tight junction protein, zona occludens-1. Moreover, EphA2(-/- brains had significantly lower levels of the pro-apoptotic proteins, cleaved caspase-3 and BAX, and higher levels of the anti-apoptotic protein, Bcl-2 as compared to WT group. We confirmed that isolated WT cortical neurons express the EphA2 receptor and its ligands (ephrin-A1-A3. Furthermore, expression of all four proteins was increased in WT primary cortical neurons following 24 h of glucose deprivation, and in the brains of WT mice following stroke. Glucose deprivation induced less cell death in primary neurons from EphA2(-/- compared with WT mice. In conclusion, our data provide the first evidence that the EphA2 receptor directly contributes to blood-brain barrier damage and neuronal death following ischemic stroke.

Loss of EphA4 impairs short-term spatial recognition memory performance and locomotor habituation.

Science.gov (United States)

Willi, R; Winter, C; Wieske, F; Kempf, A; Yee, B K; Schwab, M E; Singer, P

2012-11-01

EphA4 receptor (EphA4) tyrosine kinase is an important regulator of central nervous system development and synaptic plasticity in the mature brain, but its relevance to the control of normal behavior remains largely unexplored. This study is the first attempt to obtain a behavioral profile of constitutive homozygous and heterozygous EphA4 knockout mice. A deficit in locomotor habituation in the open field, impairment in spatial recognition in the Y-maze and reduced probability of spatial spontaneous alternation in the T-maze were identified in homozygous EphA4(-/-) mice, while heterozygo us EphA4(+/-) mice appeared normal on these tests in comparison with wild-type (WT) controls. The multiple phenotypes observed in EphA4(-/-) mice might stem from an underlying deficit in habituation learning, reflecting an elementary form of nonassociative learning that is in contrast to Pavlovian associative learning, which appeared unaffected by EphA4 disruption. A deficit in motor coordination on the accelerating rotarod was also demonstrated only in EphA4(-/-) mice--a finding in keeping with the presence of abnormal gait in EphA4(-/-) mice--although they were able to improve performance over training. There was no evidence for substantial changes in major neurochemical markers in various brain regions rich in EphA4 as shown by post-mortem analysis. This excludes the possibility of major neurochemical compensation in the brain of EphA4(-/-) mice. In summary, we have demonstrated for the first time the behavioral significance of EphA4 disruption, supporting further investigation of EphA4 as a possible target for behavioral interventions where habituation deficits are prominent. © 2012 The Authors. Genes, Brain and Behavior © 2012 Blackwell Publishing Ltd and International Behavioural and Neural Genetics Society.

Reph, a regulator of Eph receptor expression in the Drosophila melanogaster optic lobe.

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Richard E Dearborn

Full Text Available Receptors of the Eph family of tyrosine kinases and their Ephrin ligands are involved in developmental processes as diverse as angiogenesis, axon guidance and cell migration. However, our understanding of the Eph signaling pathway is incomplete, and could benefit from an analysis by genetic methods. To this end, we performed a genetic modifier screen for mutations that affect Eph signaling in Drosophila melanogaster. Several dozen loci were identified on the basis of their suppression or enhancement of an eye defect induced by the ectopic expression of Ephrin during development; many of these mutant loci were found to disrupt visual system development. One modifier locus, reph (regulator of eph expression, was characterized in molecular detail and found to encode a putative nuclear protein that interacts genetically with Eph signaling pathway mutations. Reph is an autonomous regulator of Eph receptor expression, required for the graded expression of Eph protein and the establishment of an optic lobe axonal topographic map. These results reveal a novel component of the regulatory pathway controlling expression of eph and identify reph as a novel factor in the developing visual system.

Progesterone receptor activates Msx2 expression by downregulating TNAP/Akp2 and activating the Bmp pathway in EpH4 mouse mammary epithelial cells.

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Jodie M Fleming

Full Text Available Previously we demonstrated that EpH4 mouse mammary epithelial cells induced the homeobox transcription factor Msx2 either when transfected with the progesterone receptor (PR or when treated with Bmp2/4. Msx2 upregulation was unaffected by Wnt inhibitors s-FRP or Dkk1, but was inhibited by the Bmp antagonist Noggin. We therefore hypothesized that PR signaling to Msx2 acts through the Bmp receptor pathway. Herein, we confirm that transcripts for Alk2/ActR1A, a non-canonical BmpR Type I, are upregulated in mammary epithelial cells overexpressing PR (EpH4-PR. Increased phosphorylation of Smads 1,5, 8, known substrates for Alk2 and other BmpR Type I proteins, was observed as was their translocation to the nucleus in EpH4-PR cells. Analysis also showed that Tissue Non-Specific Alkaline Phosphatase (TNAP/Akp2 was also found to be downregulated in EpH4-PR cells. When an Akp2 promoter-reporter construct containing a ½PRE site was transfected into EpH4-PR cells, its expression was downregulated. Moreover, siRNA mediated knockdown of Akp2 increased both Alk2 and Msx2 expression. Collectively these data suggest that PR inhibition of Akp2 results in increased Alk2 activity, increased phosphorylation of Smads 1,5,8, and ultimately upregulation of Msx2. These studies imply that re-activation of the Akp2 gene could be helpful in downregulating aberrant Msx2 expression in PR+ breast cancers.

EphB2 activity plays a pivotal role in pediatric medulloblastoma cell adhesion and invasion

NARCIS (Netherlands)

Sikkema, Arend H.; den Dunnen, Wilfred F. A.; Hulleman, Esther; van Vuurden, Dannis G.; Garcia-Manero, Guillermo; Yang, Hui; Scherpen, Frank J. G.; Kampen, Kim R.; Hoving, Eelco W.; Kamps, Willem A.; Diks, Sander H.; Peppelenbosch, Maikel P.; de Bont, Eve Line S. J. M.

Eph/ephrin signaling has bcen implicated in various types of key cancer-enhancing processes, like migration, proliferation, and angiogenesis. In medulloblastoma, invading tumor cells characteristically lead to early recurrence and a decreased prognosis. Based on kinase-activity profiling data

EphA2 is a functional receptor for the growth factor progranulin.

Science.gov (United States)

Neill, Thomas; Buraschi, Simone; Goyal, Atul; Sharpe, Catherine; Natkanski, Elizabeth; Schaefer, Liliana; Morrione, Andrea; Iozzo, Renato V

2016-12-05

Although the growth factor progranulin was discovered more than two decades ago, the functional receptor remains elusive. Here, we discovered that EphA2, a member of the large family of Ephrin receptor tyrosine kinases, is a functional signaling receptor for progranulin. Recombinant progranulin bound with high affinity to EphA2 in both solid phase and solution. Interaction of progranulin with EphA2 caused prolonged activation of the receptor, downstream stimulation of mitogen-activated protein kinase and Akt, and promotion of capillary morphogenesis. Furthermore, we found an autoregulatory mechanism of progranulin whereby a feed-forward loop occurred in an EphA2-dependent manner that was independent of the endocytic receptor sortilin. The discovery of a functional signaling receptor for progranulin offers a new avenue for understanding the underlying mode of action of progranulin in cancer progression, tumor angiogenesis, and perhaps neurodegenerative diseases. © 2016 Neill et al.

The roles of Eph receptors in contextual fear conditioning memory formation.

Science.gov (United States)

Dines, Monica; Grinberg, Svetlana; Vassiliev, Maria; Ram, Alon; Tamir, Tal; Lamprecht, Raphael

2015-10-01

Eph receptors regulate glutamate receptors functions, neuronal morphology and synaptic plasticity, cellular events believed to be involved in memory formation. In this study we aim to explore the roles of Eph receptors in learning and memory. Toward that end, we examined the roles of EphB2 and EphA4 receptors, key regulators of synaptic functions, in fear conditioning memory formation. We show that mice lacking EphB2 (EphB2(-/-)) are impaired in short- and long-term contextual fear conditioning memory. Mice that express a carboxy-terminally truncated form of EphB2 that lacks forward signaling, instead of the full EphB2, are impaired in long-term, but not short-term, contextual fear conditioning memory. Long-term contextual fear conditioning memory is attenuated in CaMKII-cre;EphA4(lx/-) mice where EphA4 is removed from all pyramidal neurons of the forebrain. Mutant mice with targeted kinase-dead EphA4 (EphA4(KD)) exhibit intact long-term contextual fear conditioning memory showing that EphA4 kinase-mediated forward signaling is not needed for contextual fear memory formation. The ability to form long-term conditioned taste aversion (CTA) memory is not impaired in the EphB2(-/-) and CaMKII-cre;EphA4(lx/-) mice. We conclude that EphB2 forward signaling is required for long-term contextual fear conditioning memory formation. In contrast, EphB2 mediates short-term contextual fear conditioning memory formation in a forward signaling-independent manner. EphA4 mediates long-term contextual fear conditioning memory formation in a kinase-independent manner. Copyright © 2015 Elsevier Inc. All rights reserved.

Impaired EphA4 signaling leads to congenital hydronephrosis, renal injury, and hypertension

DEFF Research Database (Denmark)

Sällström, Johan; Peuckert, Christiane; Gao, Xiang

2013-01-01

Experimental hydronephrosis induced by partial ureteral obstruction at 3 wk of age causes hypertension and renal impairment in adult rats and mice. Signaling by Ephrin receptors (Eph) and their ligands (ephrins) importantly regulates embryonic development. Genetically modified mice, where...... the cytoplasmic domain of the EphA4 receptor has been substituted by enhanced green fluorescent protein (EphA4(gf/gf)), develop spontaneous hydronephrosis and provide a model for further studies of the disorder. The present study aimed to determine if animals with congenital hydronephrosis develop hypertension...... and renal injuries, similar to that of experimental hydronephrosis. Ultrasound and Doppler techniques were used to visualize renal impairment in the adult mice. Telemetric blood pressure measurements were performed in EphA4(gf/gf) mice and littermate controls (EphA4(+/+)) during normal (0.7% NaCl)- and high...

A Novel Occulta-Type Spina Bifida Mediated by Murine Double Heterozygotes EphA2 and EphA4 Receptor Tyrosine Kinases

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Nor Linda Abdullah

2017-12-01

Full Text Available Members of the Eph receptor tyrosine kinase have previously been implicated in cranial neural tube development. Failure of neural tube closure leads to the devastating conditions known as anencephaly and spina bifida. EphA2 and EphA4 are expressed at the tips of the closing spinal neural folds prior and during neural tube closure. We investigated the possible role of murine EphA2 and EphA4 during the last step of primary neural tube closure, which is adhesion and fusion. The individual mouse knockouts of EphA2 and EphA4 per se do not exhibit neural tube defects (NTDs. The embryos generated by the crossing of double heterozygotes Epha2tm1Jrui/+Epha4rb-2J/+ displayed NTDs with a wide degree of severity including close exencephaly and close spina bifida (spina bifida occulta. Interestingly, mutants displaying NTDs had skin covering the underlying lesion. The tissue sections revealed the elevated neural folds had not adhered and fused. The phenotypes seen in Epha2tm1Jrui/+Epha4rb-2J/+ double heterozygous embryos suggest both genes play a compensatory role with each other in the adhesion and fusion of the neural tube. In this study, there exists a >50% penetrance of NTDs in the mouse mutants, which genetically have a single allele each of EphA2 and EphA4 absent.

EphA4 is Involved in Sleep Regulation but Not in the Electrophysiological Response to Sleep Deprivation.

Science.gov (United States)

Freyburger, Marlène; Pierre, Audrey; Paquette, Gabrielle; Bélanger-Nelson, Erika; Bedont, Joseph; Gaudreault, Pierre-Olivier; Drolet, Guy; Laforest, Sylvie; Blackshaw, Seth; Cermakian, Nicolas; Doucet, Guy; Mongrain, Valérie

2016-03-01

Optimal sleep is ensured by the interaction of circadian and homeostatic processes. Although synaptic plasticity seems to contribute to both processes, the specific players involved are not well understood. The EphA4 tyrosine kinase receptor is a cell adhesion protein regulating synaptic plasticity. We investigated the role of EphA4 in sleep regulation using electrocorticography in mice lacking EphA4 and gene expression measurements. EphA4 knockout (KO) mice, Clock(Δ19/Δ19) mutant mice and littermates, C57BL/6J and CD-1 mice, and Sprague-Dawley rats were studied under a 12 h light: 12 h dark cycle, under undisturbed conditions or 6 h sleep deprivation (SLD), and submitted to a 48 h electrophysiological recording and/or brain sampling at different time of day. EphA4 KO mice showed less rapid eye movement sleep (REMS), enhanced duration of individual bouts of wakefulness and nonrapid eye movement sleep (NREMS) during the light period, and a blunted daily rhythm of NREMS sigma activity. The NREMS delta activity response to SLD was unchanged in EphA4 KO mice. However, SLD increased EphA4 expression in the thalamic/hypothalamic region in C57BL/6J mice. We further show the presence of E-boxes in the promoter region of EphA4, a lower expression of EphA4 in Clock mutant mice, a rhythmic expression of EphA4 ligands in several brain areas, expression of EphA4 in the suprachiasmatic nuclei of the hypothalamus (SCN), and finally an unchanged number of cells expressing Vip, Grp and Avp in the SCN of EphA4 KO mice. Our results suggest that EphA4 is involved in circadian sleep regulation. © 2016 Associated Professional Sleep Societies, LLC.

Differential gene expression in the EphA4 knockout spinal cord and analysis of the inflammatory response following spinal cord injury.

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Kathryn M Munro

Full Text Available Mice lacking the axon guidance molecule EphA4 have been shown to exhibit extensive axonal regeneration and functional recovery following spinal cord injury. To assess mechanisms by which EphA4 may modify the response to neural injury a microarray was performed on spinal cord tissue from mice with spinal cord injury and sham injured controls. RNA was purified from spinal cords of adult EphA4 knockout and wild-type mice four days following lumbar spinal cord hemisection or laminectomy only and was hybridised to Affymetrix All-Exon Array 1.0 GeneChips™. While subsequent analyses indicated that several pathways were altered in EphA4 knockout mice, of particular interest was the attenuated expression of a number of inflammatory genes, including Arginase 1, expression of which was lower in injured EphA4 knockout compared to wild-type mice. Immunohistological analyses of different cellular components of the immune response were then performed in injured EphA4 knockout and wildtype spinal cords. While numbers of infiltrating CD3+ T cells were low in the hemisection model, a robust CD11b+ macrophage/microglial response was observed post-injury. There was no difference in the overall number or spread of macrophages/activated microglia in injured EphA4 knockout compared to wild-type spinal cords at 2, 4 or 14 days post-injury, however a lower proportion of Arginase-1 immunoreactive macrophages/activated microglia was observed in EphA4 knockout spinal cords at 4 days post-injury. Subtle alterations in the neuroinflammatory response in injured EphA4 knockout spinal cords may contribute to the regeneration and recovery observed in these mice following injury.

Axo-Glia Interaction Preceding CNS Myelination Is Regulated by Bidirectional Eph-Ephrin Signaling

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Cecilie Linneberg

2015-09-01

Full Text Available In the central nervous system, myelination of axons is required to ensure fast saltatory conduction and for survival of neurons. However, not all axons are myelinated, and the molecular mechanisms involved in guiding the oligodendrocyte processes toward the axons to be myelinated are not well understood. Only a few negative or positive guidance clues that are involved in regulating axo-glia interaction prior to myelination have been identified. One example is laminin, known to be required for early axo-glia interaction, which functions through α6β1 integrin. Here, we identify the Eph-ephrin family of guidance receptors as novel regulators of the initial axo-glia interaction, preceding myelination. We demonstrate that so-called forward and reverse signaling, mediated by members of both Eph and ephrin subfamilies, has distinct and opposing effects on processes extension and myelin sheet formation. EphA forward signaling inhibits oligodendrocyte process extension and myelin sheet formation, and blocking of bidirectional signaling through this receptor enhances myelination. Similarly, EphB forward signaling also reduces myelin membrane formation, but in contrast to EphA forward signaling, this occurs in an integrin-dependent manner, which can be reversed by overexpression of a constitutive active β1-integrin. Furthermore, ephrin-B reverse signaling induced by EphA4 or EphB1 enhances myelin sheet formation. Combined, this suggests that the Eph-ephrin receptors are important mediators of bidirectional signaling between axons and oligodendrocytes. It further implies that balancing Eph-ephrin forward and reverse signaling is important in the selection process of axons to be myelinated.

EphB4 localises to the nucleus of prostate cancer cells

International Nuclear Information System (INIS)

Mertens-Walker, Inga; Lisle, Jessica E.; Nyberg, William A.; Stephens, Carson R.; Burke, Leslie; Rutkowski, Raphael; Herington, Adrian C.; Stephenson, Sally-Anne

2015-01-01

The EphB4 receptor tyrosine kinase is over-expressed in a variety of different epithelial cancers including prostate where it has been shown to be involved in survival, migration and angiogenesis. We report here that EphB4 also resides in the nucleus of prostate cancer cell lines. We used in silico methods to identify a bipartite nuclear localisation signal (NLS) in the extracellular domain and a monopartite NLS sequence in the intracellular kinase domain of EphB4. To determine whether both putative NLS sequences were functional, fragments of the EphB4 sequence containing each NLS were cloned to create EphB4NLS-GFP fusion proteins. Localisation of both NLS-GFP proteins to the nuclei of transfected cells was observed, demonstrating that EphB4 contains two functional NLS sequences. Mutation of the key amino residues in both NLS sequences resulted in diminished nuclear accumulation. As nuclear translocation is often dependent on importins we confirmed that EphB4 and importin-α can interact. To assess if nuclear EphB4 could be implicated in gene regulatory functions potential EphB4-binding genomic loci were identified using chromatin immunoprecipitation and Lef1 was confirmed as a potential target of EphB4-mediated gene regulation. These novel findings add further complexity to the biology of this important cancer-associated receptor. - Highlights: • The EphB4 protein can be found in the nucleus of prostate cancer cell lines. • EphB4 contains two functional nuclear localisation signals. • Chromatin immunoprecipitation has identified potential genome sequences to which EphB4 binds. • Lef1 is a confirmed target for EphB4-mediated gene regulation

EphB4 localises to the nucleus of prostate cancer cells

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Mertens-Walker, Inga, E-mail: inga.mertenswalker@qut.edu.au [Institute of Health and Biomedical Innovation, Queensland University of Technology, Woolloongabba, QLD (Australia); Australian Prostate Cancer Research Centre—Queensland, Translational Research Institute, 37 Kent Street, Woolloongabba 4102, QLD (Australia); Lisle, Jessica E. [Institute of Health and Biomedical Innovation, Queensland University of Technology, Woolloongabba, QLD (Australia); Australian Prostate Cancer Research Centre—Queensland, Translational Research Institute, 37 Kent Street, Woolloongabba 4102, QLD (Australia); Nyberg, William A. [Institute of Health and Biomedical Innovation, Queensland University of Technology, Woolloongabba, QLD (Australia); Stephens, Carson R. [Institute of Health and Biomedical Innovation, Queensland University of Technology, Woolloongabba, QLD (Australia); Australian Prostate Cancer Research Centre—Queensland, Translational Research Institute, 37 Kent Street, Woolloongabba 4102, QLD (Australia); Burke, Leslie [Institute of Health and Biomedical Innovation, Queensland University of Technology, Woolloongabba, QLD (Australia); Rutkowski, Raphael; Herington, Adrian C.; Stephenson, Sally-Anne [Institute of Health and Biomedical Innovation, Queensland University of Technology, Woolloongabba, QLD (Australia); Australian Prostate Cancer Research Centre—Queensland, Translational Research Institute, 37 Kent Street, Woolloongabba 4102, QLD (Australia)

2015-04-10

The EphB4 receptor tyrosine kinase is over-expressed in a variety of different epithelial cancers including prostate where it has been shown to be involved in survival, migration and angiogenesis. We report here that EphB4 also resides in the nucleus of prostate cancer cell lines. We used in silico methods to identify a bipartite nuclear localisation signal (NLS) in the extracellular domain and a monopartite NLS sequence in the intracellular kinase domain of EphB4. To determine whether both putative NLS sequences were functional, fragments of the EphB4 sequence containing each NLS were cloned to create EphB4NLS-GFP fusion proteins. Localisation of both NLS-GFP proteins to the nuclei of transfected cells was observed, demonstrating that EphB4 contains two functional NLS sequences. Mutation of the key amino residues in both NLS sequences resulted in diminished nuclear accumulation. As nuclear translocation is often dependent on importins we confirmed that EphB4 and importin-α can interact. To assess if nuclear EphB4 could be implicated in gene regulatory functions potential EphB4-binding genomic loci were identified using chromatin immunoprecipitation and Lef1 was confirmed as a potential target of EphB4-mediated gene regulation. These novel findings add further complexity to the biology of this important cancer-associated receptor. - Highlights: • The EphB4 protein can be found in the nucleus of prostate cancer cell lines. • EphB4 contains two functional nuclear localisation signals. • Chromatin immunoprecipitation has identified potential genome sequences to which EphB4 binds. • Lef1 is a confirmed target for EphB4-mediated gene regulation.

Restriction of Receptor Movement Alters Cellular Response: Physical Force Sensing by EphA2

Energy Technology Data Exchange (ETDEWEB)

Salaita, Khalid; Nair, Pradeep M; Petit, Rebecca S; Neve, Richard M; Das, Debopriya; Gray, Joe W; Groves, Jay T

2009-09-09

Activation of the EphA2 receptor tyrosine kinase by ephrin-A1 ligands presented on apposed cell surfaces plays important roles in development and exhibits poorly understood functional alterations in cancer. We reconstituted this intermembrane signaling geometry between live EphA2-expressing human breast cancer cells and supported membranes displaying laterally mobile ephrin-A1. Receptor-ligand binding, clustering, and subsequent lateral transport within this junction were observed. EphA2 transport can be blocked by physical barriers nanofabricated onto the underlying substrate. This physical reorganization of EphA2 alters the cellular response to ephrin-A1, as observed by changes in cytoskeleton morphology and recruitment of a disintegrin and metalloprotease 10. Quantitative analysis of receptor-ligand spatial organization across a library of 26 mammary epithelial cell lines reveals characteristic differences that strongly correlate with invasion potential. These observations reveal a mechanism for spatio-mechanical regulation of EphA2 signaling pathways.

Should the Equilibrium Point Hypothesis (EPH) be Considered a Scientific Theory?

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Sainburg, Robert L

2015-04-01

The purpose of this commentary is to discuss factors that limit consideration of the equilibrium point hypothesis as a scientific theory. The EPH describes control of motor neuron threshold through the variable lambda, which corresponds to a unique referent configuration for a muscle, joint, or combination of joints. One of the most compelling features of the equilibrium point hypothesis is the integration of posture and movement control into a single mechanism. While the essential core of the hypothesis is based upon spinal circuitry interacting with peripheral mechanics, the proponents have extended the theory to include the higher-level processes that generate lambda, and in doing so, imposed an injunction against the supraspinal nervous system modeling, computing, or predicting dynamics. This limitation contradicts evidence that humans take account of body and environmental dynamics in motor selection, motor control, and motor adaptation processes. A number of unresolved limitations to the EPH have been debated in the literature for many years, including whether muscle resistance to displacement, measured during movement, is adequate to support this form of control, violations in equifinality predictions, spinal circuits that alter the proposed invariant characteristic for muscles, and limitations in the description of how the complexity of spinal circuitry might be integrated to yield a unique and stable equilibrium position for a given motor neuron threshold. In addition, an important empirical limitation of EPH is the measurement of the invariant characteristic, which needs to be done under a constant central state. While there is no question that the EPH is an elegant and generative hypothesis for motor control research, the claim that this hypothesis has reached the status of a scientific theory is premature.

Perineuronal Net Protein Neurocan Inhibits NCAM/EphA3 Repellent Signaling in GABAergic Interneurons.

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Sullivan, Chelsea S; Gotthard, Ingo; Wyatt, Elliott V; Bongu, Srihita; Mohan, Vishwa; Weinberg, Richard J; Maness, Patricia F

2018-04-18

Perineuronal nets (PNNs) are implicated in closure of critical periods of synaptic plasticity in the brain, but the molecular mechanisms by which PNNs regulate synapse development are obscure. A receptor complex of NCAM and EphA3 mediates postnatal remodeling of inhibitory perisomatic synapses of GABAergic interneurons onto pyramidal cells in the mouse frontal cortex necessary for excitatory/inhibitory balance. Here it is shown that enzymatic removal of PNN glycosaminoglycan chains decreased the density of GABAergic perisomatic synapses in mouse organotypic cortical slice cultures. Neurocan, a key component of PNNs, was expressed in postnatal frontal cortex in apposition to perisomatic synapses of parvalbumin-positive interneurons. Polysialylated NCAM (PSA-NCAM), which is required for ephrin-dependent synapse remodeling, bound less efficiently to neurocan than mature, non-PSA-NCAM. Neurocan bound the non-polysialylated form of NCAM at the EphA3 binding site within the immunoglobulin-2 domain. Neurocan inhibited NCAM/EphA3 association, membrane clustering of NCAM/EphA3 in cortical interneuron axons, EphA3 kinase activation, and ephrin-A5-induced growth cone collapse. These studies delineate a novel mechanism wherein neurocan inhibits NCAM/EphA3 signaling and axonal repulsion, which may terminate postnatal remodeling of interneuron axons to stabilize perisomatic synapses in vivo.

Regulation of hippocampal synaptic plasticity by the tyrosine kinase receptor, REK7/EphA5, and its ligand, AL-1/Ephrin-A5.

Science.gov (United States)

Gao, W Q; Shinsky, N; Armanini, M P; Moran, P; Zheng, J L; Mendoza-Ramirez, J L; Phillips, H S; Winslow, J W; Caras, I W

1998-08-01

The Eph-related tyrosine kinase receptor, REK7/EphA5, mediates the effects of AL-1/Ephrin-A5 and related ligands and is involved in the guidance of retinal, cortical, and hippocampal axons during development. The continued expression of REK7/EphA5 in the adult brain, in particular in areas associated with a high degree of synaptic plasticity such as the hippocampus, raises the question of its function in the mature nervous system. In this report we examined the role of REK7/EphA5 in synaptic remodeling by asking if agents that either block or activate REK7/EphA5 affect synaptic strength in hippocampal slices from adult mouse brain. We show that a REK7/EphA5 antagonist, soluble REK7/EphA5-IgG, impairs the induction of long-term potentiation (LTP) without affecting other synaptic parameters such as normal synaptic transmission or paired-pulse facilitation. In contrast, perfusion with AL-1/Ephrin-A5-IgG, an activator of REK7/EphA5, induces a sustained increase in normal synaptic transmission that partially mimics LTP. The sustained elevation of normal synaptic transmission could be attributable to a long-lasting binding of the AL-1/Ephrin-A5-IgG to the endogenous REK7/EphA5 receptor, as revealed by immunohistochemistry. Furthermore, maximal electrical induction of LTP occludes the potentiating effects of subsequent treatment with AL-1/Ephrin-A5-IgG. Taken together these results implicate REK7/EphA5 in the regulation of synaptic plasticity in the mature hippocampus and suggest that REK7/EphA5 activation is recruited in the LTP induced by tetanization. Copyright 1998 Academic Press.

Eph receptor A10 has a potential as a target for a prostate cancer therapy

International Nuclear Information System (INIS)

Nagano, Kazuya; Yamashita, Takuya; Inoue, Masaki; Higashisaka, Kazuma; Yoshioka, Yasuo; Abe, Yasuhiro; Mukai, Yohei; Kamada, Haruhiko

2014-01-01

Highlights: • EphA10 mRNA is overexpressed in breast, prostate and colon cancer cell lines. • EphA10 is overexpressed in clinical prostate tumors at mRNA and protein levels. • Anti-EphA10 antibodies were cytotoxic on EphA10-positive prostate cancer cells. - Abstract: We recently identified Eph receptor A10 (EphA10) as a novel breast cancer-specific protein. Moreover, we also showed that an in-house developed anti-EphA10 monoclonal antibody (mAb) significantly inhibited proliferation of breast cancer cells, suggesting EphA10 as a promising target for breast cancer therapy. However, the only other known report for EphA10 was its expression in the testis at the mRNA level. Therefore, the potency of EphA10 as a drug target against cancers other than the breast is not known. The expression of EphA10 in a wide variety of cancer cells was studied and the potential of EphA10 as a drug target was evaluated. Screening of EphA10 mRNA expression showed that EphA10 was overexpressed in breast cancer cell lines as well as in prostate and colon cancer cell lines. Thus, we focused on prostate cancers in which EphA10 expression was equivalent to that in breast cancers. As a result, EphA10 expression was clearly shown in clinical prostate tumor tissues as well as in cell lines at the mRNA and protein levels. In order to evaluate the potential of EphA10 as a drug target, we analyzed complement-dependent cytotoxicity effects of anti-EphA10 mAb and found that significant cytotoxicity was mediated by the expression of EphA10. Therefore, the idea was conceived that the overexpression of EphA10 in prostate cancers might have a potential as a target for prostate cancer therapy, and formed the basis for the studies reported here

Receptor tyrosine kinase EphA5 is a functional molecular target in human lung cancer.

Science.gov (United States)

Staquicini, Fernanda I; Qian, Ming D; Salameh, Ahmad; Dobroff, Andrey S; Edwards, Julianna K; Cimino, Daniel F; Moeller, Benjamin J; Kelly, Patrick; Nunez, Maria I; Tang, Ximing; Liu, Diane D; Lee, J Jack; Hong, Waun Ki; Ferrara, Fortunato; Bradbury, Andrew R M; Lobb, Roy R; Edelman, Martin J; Sidman, Richard L; Wistuba, Ignacio I; Arap, Wadih; Pasqualini, Renata

2015-03-20

Lung cancer is often refractory to radiotherapy, but molecular mechanisms of tumor resistance remain poorly defined. Here we show that the receptor tyrosine kinase EphA5 is specifically overexpressed in lung cancer and is involved in regulating cellular responses to genotoxic insult. In the absence of EphA5, lung cancer cells displayed a defective G1/S cell cycle checkpoint, were unable to resolve DNA damage, and became radiosensitive. Upon irradiation, EphA5 was transported into the nucleus where it interacted with activated ATM (ataxia-telangiectasia mutated) at sites of DNA repair. Finally, we demonstrate that a new monoclonal antibody against human EphA5 sensitized lung cancer cells and human lung cancer xenografts to radiotherapy and significantly prolonged survival, thus suggesting the likelihood of translational applications. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Optimizing EphA2-CAR T Cells for the Adoptive Immunotherapy of Glioma

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Zhongzhen Yi

2018-06-01

Full Text Available Glioblastoma is the most aggressive primary brain tumor in humans and is virtually incurable with conventional therapies. Chimeric antigen receptor (CAR T cell therapy targeting the glioblastoma antigen EphA2 is an attractive approach to improve outcomes because EphA2 is expressed highly in glioblastoma but only at low levels in normal brain tissue. Building upon our previous findings in this area, we generated and evaluated a panel of EphA2-specific CARs. We demonstrate here that T cells expressing CD28.ζ and 41BB.ζ CARs with short spacers had similar effector function, resulting in potent antitumor activity. In addition, incorporating the 41BB signaling domain into CD28.ζ CARs did not improve CAR T cell function. While we could not determine functional differences between CD28.ζ, 41BB.ζ, and CD28.41BB.ζ CAR T cells, we selected CD28.ζ CAR T cells for further clinical development based on safety consideration. Keywords: GBM, CAR T cells, EphA2, brain tumor

The Blood-Brain Barrier and the EphR/Ephrin System: Perspectives on a Link Between Neurovascular and Neuropsychiatric Disorders

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Victoria A. Malik

2018-04-01

Full Text Available Interactions among endothelial cells (EC forming blood vessels and their surrounding cell types are essential to establish the blood-brain barrier (BBB, an integral part of the neurovascular unit (NVU. Research on the NVU has recently seen a renaissance to especially understand the neurobiology of vascular and brain pathologies and their frequently occurring comorbidities. Diverse signaling molecules activated in the near proximity of blood vessels trigger paracellular pathways which regulate the formation and stabilization of tight junctions (TJ between EC and thereby influence BBB permeability. Among regulatory molecules, the erythropoietin-producing-hepatocellular carcinoma receptors (EphR and their Eph receptor-interacting signals (ephrins play a pivotal role in EC differentiation, angiogenesis and BBB integrity. Multiple EphR-ligand interactions between EC and other cell types influence different aspects of angiogenesis and BBB formation. Such interactions additionally control BBB sealing properties and thus the penetration of substances into the brain parenchyma. Thus, they play critical roles in the healthy brain and during the pathogenesis of brain disorders. In this mini-review article, we aim at integrating the constantly growing literature about the functional roles of the EphR/ephrin system for the development of the vascular system and the BBB and in the pathogenesis of neurovascular and neuropsychiatric disorders. We suggest the hypothesis that a disrupted EphR/ephrin signaling at the BBB might represent an underappreciated molecular hub of disease comorbidity. Finally, we propose the possibility that the EphR/ephrin system bears the potential of becoming a novel target for the development of alternative therapeutic treatments, focusing on such comorbidities.

Comparative 3'UTR analysis allows identification of regulatory clusters that drive Eph/ephrin expression in cancer cell lines.

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Jennifer Winter

Full Text Available Eph receptors are the largest family of receptor tyrosine kinases. Together with their ligands, the ephrins, they fulfill multiple biological functions. Aberrant expression of Ephs/ephrins leading to increased Eph receptor to ephrin ligand ratios is a critical factor in tumorigenesis, indicating that tight regulation of Eph and ephrin expression is essential for normal cell behavior. The 3'-untranslated regions (3'UTRs of transcripts play an important yet widely underappreciated role in the control of protein expression. Based on the assumption that paralogues of large gene families might exhibit a conserved organization of regulatory elements in their 3'UTRs we applied a novel bioinformatics/molecular biology approach to the 3'UTR sequences of Eph/ephrin transcripts. We identified clusters of motifs consisting of cytoplasmic polyadenylation elements (CPEs, AU-rich elements (AREs and HuR binding sites. These clusters bind multiple RNA-stabilizing and destabilizing factors, including HuR. Surprisingly, despite its widely accepted role as an mRNA-stabilizing protein, we further show that binding of HuR to these clusters actually destabilizes Eph/ephrin transcripts in tumor cell lines. Consequently, knockdown of HuR greatly modulates expression of multiple Ephs/ephrins at both the mRNA and protein levels. Together our studies suggest that overexpression of HuR as found in many progressive tumors could be causative for disarranged Eph receptor to ephrin ligand ratios leading to a higher degree of tissue invasiveness.

RINL, guanine nucleotide exchange factor Rab5-subfamily, is involved in the EphA8-degradation pathway with odin.

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Hiroaki Kajiho

Full Text Available The Rab family of small guanosine triphosphatases (GTPases plays a vital role in membrane trafficking. Its active GTP-bound state is driven by guanine nucleotide-exchange factors (GEFs. Ras and Rab interactor (or Ras interaction/interference-like (RINL, which contains a conserved VPS9 domain critical for GEF action, was recently identified as a new Rab5 subfamily GEF in vitro. However, its detailed function and interacting molecules have not yet been fully elucidated. Here we found that RINL has GEF activity for the Rab5 subfamily proteins by measuring their GTP-bound forms in cultured cells. We also found that RINL interacts with odin, a member of the ankyrin-repeat and sterile-alpha motif (SAM domain-containing (Anks protein family. In addition, the Eph tyrosine kinase receptor EphA8 formed a ternary complex with both RINL and odin. Interestingly, RINL expression in cultured cells reduced EphA8 levels in a manner dependent on both its GEF activity and interaction with odin. In addition, knockdown of RINL increased EphA8 level in HeLa cells. Our findings suggest that RINL, as a GEF for Rab5 subfamily, is implicated in the EphA8-degradation pathway via its interaction with odin.

Discovery and characterization of a novel cyclic peptide that effectively inhibits ephrin binding to the EphA4 receptor and displays anti-angiogenesis activity.

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Xiaofeng Han

Full Text Available The EphA4 receptor tyrosine kinase regulates a variety of physiological and pathological processes during neural development and the formation of tumor blood vessels; thus, it represents a new and promising therapeutic target. We used a combination of phage peptide display and computer modeling/docking approaches and discovered a novel cyclic nonapeptide, now designated TYY. This peptide selectively inhibits the binding of the ephrinA5 ligand with EphA4 and significantly blocks angiogenesis in a 3D matrigel culture system. Molecular docking reveals that TYY recognizes the same binding pocket on EphA4 that the natural ephrin ligand binds to and that the Tyr3 and Tyr4 side chains of TYY are both critical for the TYY/EphA4 interaction. The discovery of TYY introduces a valuable probe of EphA4 function and a new lead for EphA4-targeted therapeutic development.

EphA4 blockers promote axonal regeneration and functional recovery following spinal cord injury in mice.

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Yona Goldshmit

Full Text Available Upregulation and activation of developmental axon guidance molecules, such as semaphorins and members of the Eph receptor tyrosine kinase family and their ligands, the ephrins, play a role in the inhibition of axonal regeneration following injury to the central nervous system. Previously we have demonstrated in a knockout model that axonal regeneration following spinal cord injury is promoted in the absence of the axon guidance protein EphA4. Antagonism of EphA4 was therefore proposed as a potential therapy to promote recovery from spinal cord injury. To further assess this potential, two soluble recombinant blockers of EphA4, unclustered ephrin-A5-Fc and EphA4-Fc, were examined for their ability to promote axonal regeneration and to improve functional outcome following spinal cord hemisection in wildtype mice. A 2-week administration of either of these blockers following spinal cord injury was sufficient to promote substantial axonal regeneration and functional recovery by 5 weeks following injury. Both inhibitors produced a moderate reduction in astrocytic gliosis, indicating that much of the effect of the blockers may be due to promotion of axon growth. These studies provide definitive evidence that soluble inhibitors of EphA4 function offer considerable therapeutic potential for the treatment of spinal cord injury and may have broader potential for the treatment of other central nervous system injuries.

EphA4 defines a class of excitatory locomotor-related interneurons

DEFF Research Database (Denmark)

Butt, S. J B; Lundfald, Line; Kiehn, Ole

2005-01-01

of these interneurons provide direct excitation to ipsilateral motor neurons as determined by spike-triggered averaging of the local ventral root DC trace. Our findings substantiate the role of EphA4-positive interneurons as significant components of the ipsilateral locomotor network and describe a group of putative...... of the role of these cells in the network. One such marker is the EphA4 axon guidance receptor. EphA4-null mice display an abnormal rabbit-like hopping gait that is thought to be the result of synchronization of the normally alternating, bilateral locomotor network via aberrant crossed connections....... In this study, we have performed whole-cell patch clamp on EphA4-positive interneurons in the flexor region (L2) of the locomotor network. We provide evidence that although EphA4 positive interneurons are not entirely a homogeneous population, most of them fire in a rhythmic manner. Moreover, a subset...

c-Fos downregulation positively regulates EphA5 expression in a congenital hypothyroidism rat model.

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Song, Honghua; Zheng, Yuqin; Cai, Fuying; Ma, Yanyan; Yang, Jingyue; Wu, Youjia

2018-04-01

The EphA5 receptor is well established as an axon guidance molecule during neural system development and plays an important role in dendritic spine formation and synaptogenesis. Our previous study has showed that EphA5 is decreased in the developing brain of congenital hypothyroidism (CH) and the EphA5 promoter methylation modification participates in its decrease. c-Fos, a well-kown transcription factor, has been considered in association with brain development. Bioinformatics analysis showed that the EphA5 promoter region contained five putative c-fos binding sites. The chromatin immunoprecipitation (ChIP) assays were used to assess the direct binding of c-fos to the EphA5 promoter. Furthermore, dual-luciferase assays showed that these three c-fos protein binding sites were positive regulatory elements for EphA5 expression in PC12 cells. Moreover, We verified c-fos positively regulation for EphA5 expression in CH model. Q-PCR and Western blot showed that c-fos overexpression could upregulate EphA5 expression in hippocampal neurons of rats with CH. Our results suggest that c-fos positively regulates EphA5 expression in CH rat model.

A neuroprotective astrocyte state is induced by neuronal signal EphB1 but fails in ALS models.

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Tyzack, Giulia E; Hall, Claire E; Sibley, Christopher R; Cymes, Tomasz; Forostyak, Serhiy; Carlino, Giulia; Meyer, Ione F; Schiavo, Giampietro; Zhang, Su-Chun; Gibbons, George M; Newcombe, Jia; Patani, Rickie; Lakatos, András

2017-10-27

Astrocyte responses to neuronal injury may be beneficial or detrimental to neuronal recovery, but the mechanisms that determine these different responses are poorly understood. Here we show that ephrin type-B receptor 1 (EphB1) is upregulated in injured motor neurons, which in turn can activate astrocytes through ephrin-B1-mediated stimulation of signal transducer and activator of transcription-3 (STAT3). Transcriptional analysis shows that EphB1 induces a protective and anti-inflammatory signature in astrocytes, partially linked to the STAT3 network. This is distinct from the response evoked by interleukin (IL)-6 that is known to induce both pro inflammatory and anti-inflammatory processes. Finally, we demonstrate that the EphB1-ephrin-B1 pathway is disrupted in human stem cell derived astrocyte and mouse models of amyotrophic lateral sclerosis (ALS). Our work identifies an early neuronal help-me signal that activates a neuroprotective astrocytic response, which fails in ALS, and therefore represents an attractive therapeutic target.

EphA2 Is a Potential Player of Malignant Cellular Behavior in Non-Metastatic Renal Cell Carcinoma Cells but Not in Metastatic Renal Cell Carcinoma Cells.

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Cho, Min Chul; Cho, Sung Yong; Yoon, Cheol Yong; Lee, Seung Bae; Kwak, Cheol; Kim, Hyeon Hoe; Jeong, Hyeon

2015-01-01

To investigate the role of EphA2 in malignant cellular behavior in renal cell carcinoma (RCC) cells and whether FAK/RhoA signaling can act as downstream effectors of EphA2 on RCC cells. Expression of EphA2 protein in non-metastatic RCC (Caki-2 and A498), metastatic RCC cells (Caki-1 and ACHN), HEK-293 cells and prostate cancer cells (PC-3 and DU-145; positive controls of EphA2 expression) was evaluated by Western blot. Changes in mRNA or protein expression of EphA2, FAK or membrane-bound RhoA following EphA2, FAK or RhoA small interfering RNA (siRNA) transfection were determined by reverse transcription polymerase chain reaction or Western blot. The effect of siRNA treatment on cellular viability, apoptosis and invasion was analyzed by cell counting kit-8, Annexin-V and modified Matrigel-Boyden assays, respectively. In all RCC cell lines, the expression of EphA2 protein was detectable at variable levels; however, in HEK-293 cells, EphA2 expression was very low. Treatment with EphA2 siRNA significantly reduced the expression of EphA2 mRNA and protein in all RCC cell lines. For non-metastatic RCC cells (Caki-2 and A498) but not metastatic RCC cells (Caki-1 and ACHN), cellular viability, invasiveness, resistance to apoptosis, expression of membrane-bound RhoA protein and FAK phosphorylation were significantly decreased in EphA2 siRNA-treated cells compared to the control. In non-metastatic RCC cells, FAK siRNA significantly attenuated the invasiveness, resistance to apoptosis, as well as expression of membrane-bound RhoA protein without changing protein expression of EphA2. RhoA siRNA significantly decreased the malignant cellular behavior and expression of membrane-bound RhoA protein without changing EphA2 protein expression or FAK phosphorylation. Our data provide the first functional evidence that the EphA2/FAK/RhoA signaling pathway plays a critical role in the malignant cellular behavior of RCC and appears to be functional particularly in the early stage of

Investigation of the expression of the EphB4 receptor tyrosine kinase in prostate carcinoma

International Nuclear Information System (INIS)

Lee, Yen-Ching; Perren, Janeanne R; Douglas, Evelyn L; Raynor, Michael P; Bartley, Maria A; Bardy, Peter G; Stephenson, Sally-Anne

2005-01-01

The EphB4 receptor tyrosine kinase has been reported as increased in tumours originating from several different tissues and its expression in a prostate cancer xenograft model has been reported. RT-PCR, western blotting and immunohistochemical techniques were used to examine EphB4 expression and protein levels in human prostate cancer cell lines LNCaP, DU145 and PC3. Immunohistochemistry was also used to examine localisation of EphB4 in tissue samples from 15 patients with prostate carcinomas. All three prostate cancer cell lines expressed the EphB4 gene and protein. EphB4 immunoreactivity in vivo was significantly greater in human prostate cancers as compared with matched normal prostate epithelium and there appeared to be a trend towards increased expression with higher grade disease. EphB4 is expressed in prostate cancer cell lines with increased expression in human prostate cancers when compared with matched normal tissue. EphB4 may therefore be a useful anti-prostate cancer target

Cell type-specific localization of Ephs pairing with ephrin-B2 in the rat postnatal pituitary gland.

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Yoshida, Saishu; Kato, Takako; Kanno, Naoko; Nishimura, Naoto; Nishihara, Hiroto; Horiguchi, Kotaro; Kato, Yukio

2017-10-01

Sox2-expressing stem/progenitor cells in the anterior lobe of the pituitary gland form two types of micro-environments (niches): the marginal cell layer and dense cell clusters in the parenchyma. In relation to the mechanism of regulation of niches, juxtacrine signaling via ephrin and its receptor Eph is known to play important roles in various niches. The ephrin and Eph families are divided into two subclasses to create ephrin/Eph signaling in co-operation with confined partners. Recently, we reported that ephrin-B2 localizes specifically to both pituitary niches. However, the Ephs interacting with ephrin-B2 in these pituitary niches have not yet been identified. Therefore, the present study aims to identify the Ephs interacting with ephrin-B2 and the cells that produce them in the rat pituitary gland. In situ hybridization and immunohistochemistry demonstrated cell type-specific localization of candidate interacting partners for ephrin-B2, including EphA4 in cells located in the posterior lobe, EphB1 in gonadotropes, EphB2 in corticotropes, EphB3 in stem/progenitor cells and EphB4 in endothelial cells in the adult pituitary gland. In particular, double-immunohistochemistry showed cis-interactions between EphB3 and ephrin-B2 in the apical cell membranes of stem/progenitor cell niches throughout life and trans-interactions between EphB2 produced by corticotropes and ephrin-B2 located in the basolateral cell membranes of stem/progenitor cells in the early postnatal pituitary gland. These data indicate that ephrin-B2 plays a role in pituitary stem/progenitor cell niches by selective interaction with EphB3 in cis and EphB2 in trans.

Eph-B4 regulates adaptive venous remodeling to improve arteriovenous fistula patency

OpenAIRE

Protack, Clinton D.; Foster, Trenton R.; Hashimoto, Takuya; Yamamoto, Kota; Lee, Monica Y.; Kraehling, Jan R.; Bai, Hualong; Hu, Haidi; Isaji, Toshihiko; Santana, Jeans M.; Wang, Mo; Sessa, William C.; Dardik, Alan

2017-01-01

Low rates of arteriovenous fistula (AVF) maturation prevent optimal fistula use for hemodialysis; however, the mechanism of venous remodeling in the fistula environment is not well understood. We hypothesized that the embryonic venous determinant Eph-B4 mediates AVF maturation. In human AVF and a mouse aortocaval fistula model, Eph-B4 protein expression increased in the fistula vein; expression of the arterial determinant Ephrin-B2 also increased. Stimulation of Eph-B-mediated signaling with ...

Up-regulated ephrinB3/EphB3 expression in intractable temporal lobe epilepsy patients and pilocarpine induced experimental epilepsy rat model.

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Huang, Hao; Li, Ruohan; Yuan, Jinxian; Zhou, Xin; Liu, Xi; Ou, Shu; Xu, Tao; Chen, Yangmei

2016-05-15

EphB family receptor tyrosine kinases, in cooperation with cell surface-bound ephrinB ligands, play a critical role in maintenance of dendritic spine morphogenesis, axons guidance, synaptogenesis, synaptic reorganization and plasticity in the central nervous system (CNS). However, the expression pattern of ephrinB/EphB in intractable temporal lobe epilepsy (TLE) and the underlying molecular mechanisms during epileptogenesis remain poorly understood. Here we investigated the expression pattern and cellular distribution of ephrinB/EphB in intractable TLE patients and lithium chloride-pilocarpine induced TLE rats using real-time quantitative polymerase chain reaction (RT-qPCR), immunohistochemistry, double-labeled immunofluorescence and Western blot analysis. Compared to control groups, ephrinB3 and EphB3 mRNA expression were significantly up-regulated in intractable TLE patients and TLE rats, while the mRNA expression trend of ephrinB1/2 and EphB1/2/4/6 in intractable TLE patients and TLE rats were inconsistent. Western blot analysis and semi-quantitative immunohistochemistry confirmed that ephrinB3 and EphB3 protein level were up-regulated in intractable TLE patients and TLE rats. At the same time, double-labeled immunofluorescence indicate that ephrinB3 was expressed mainly in the cytoplasm and protrusions of glia and neurons, while EphB3 was expressed mainly in the cytoplasm of neurons. Taken together, up-regulated expression of ephrinB3/EphB3 in intractable TLE patients and experimental TLE rats suggested that ephrinB3/EphB3 might be involved in the pathogenesis of TLE. Copyright © 2016 Elsevier B.V. All rights reserved.

Bifunctional role of ephrin A1-Eph system in stimulating cell proliferation and protecting cells from cell death through the attenuation of ER stress and inflammatory responses in bovine mammary epithelial cells.

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Kang, Minkyung; Jeong, Wooyoung; Bae, Hyocheol; Lim, Whasun; Bazer, Fuller W; Song, Gwonhwa

2018-03-01

Structural and functional development of the mammary gland is constant in the mammary gland life cycle. Eph receptors and their ligands, ephrins, control events through cell-to-cell interactions during embryonic development, and adult tissue homeostasis; however, little information on participation of ephrin A1, a representative ligand of the Eph receptor, in the development and function of normal mammary glands is known. In this study, we demonstrated functional effects of the ephrin A1-Eph system and mechanisms of its action on bovine mammary epithelial (MAC-T) cells. The in vitro cultured MAC-T cells expressed the ephrin A1 ligand and EphA1, A2, A4, A7, and A8 among the eight members of the Eph A family. Our results revealed that ephrin A1 induced MAC-T cell cycle progression and stimulated cell proliferation with abundant expression of nucleic PCNA and cyclin D1 proteins. Additionally, ephrin A1 induced activation of intracellular signaling molecules involved in PI3 K/AKT and MAPK signaling, and the proliferation-stimulating effect of ephrin A1 was mediated by activation of these pathways. Furthermore, ephrin A1 influenced expression and activation of various ER stress-related proteins and protected MAC-T cells from stress-induced cell death. Finally, ephrin A1 alleviated LPS-induced cell death through down-regulation of inflammatory cytokines. In conclusion, the results of this study suggest that the Eph A-ephrin A1 system is a positive factor in the increase and maintenance of epithelial cells in mammary glands of cows; the signaling system contributes to development, remodeling, and functionality of normal mammary glands and could overcome mastitis in cows and other mammals. © 2017 Wiley Periodicals, Inc.

EphB1 as a Novel Drug Target to Combat Pain and Addiction

Science.gov (United States)

2016-09-01

Award Number: W81XWH-14-1-0220 Project Title: EphB1 as a Novel Drug Target to Combat Pain and Addiction Principal Investigator Name: Mark...Pain and Addiction 5a. CONTRACT NUMBER EphB1 as a Novel Drug Target to Combat Pain and Addiction 5b. GRANT NUMBER W81XWH-14-1-0220 5c. PROGRAM...SUBJECT TERMS Chronic neuropathic pain, opioid addiction , synaptic plasticity, EphB1 receptor, ephrin-B2, NMDA receptor, drug discovery 16. SECURITY

EphB1 as a Novel Drug Target to Combat Pain and Addiction

Science.gov (United States)

2015-09-01

EphB1  as  a  Novel  Drug  Target  to  Combat  Pain  and   Addiction   Principal  Investigator  Name:   Mark...Principal  Investigator   Phone  and  Email:   Phone :  214-­‐645-­‐5916   Email:  Mark.Henkemeyer@UTSouthwestern.edu   Report  Date...31 Aug 2015 4. TITLE AND SUBTITLE EphB1 as a Novel Drug Target to Combat Pain and Addiction 5a. CONTRACT NUMBER EphB1 as a Novel Drug Target to

Positively charged polymers modulate the fate of human mesenchymal stromal cells via ephrinB2/EphB4 signaling

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Ilenia De Luca

2016-09-01

Full Text Available Understanding the mechanisms by which mesenchymal stromal cells (MSCs interact with the physical properties (e.g. topography, charge, ζ-potential, and contact angle of polymeric surfaces is essential to design new biomaterials capable of regulating stem cell behavior. The present study investigated the ability of two polymers (pHM1 and pHM3 with different positive surface charge densities to modulate the differentiation of MSCs into osteoblast-like phenotype via cell-cell ephrinB2/EphB4 signaling. Although pHM1 promoted the phosphorylation of EphB4, leading to cell differentiation, pHM3, characterized by a high positive surface charge density, had no significant effect on EphB4 activation or MSCs differentiation. When the MSCs were cultured on pHM1 in the presence of a forward signaling blocking peptide, the osteoblast differentiation was compromised. Our results demonstrated that the ephrinB2/EphB4 interaction was required for MSCs differentiation into an osteoblast-like phenotype and that the presence of a high positive surface charge density altered this interaction.

Targeting EphA2-Sam and Its Interactome: Design and Evaluation of Helical Peptides Enriched in Charged Residues.

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Mercurio, Flavia A; Marasco, Daniela; Di Natale, Concetta; Pirone, Luciano; Costantini, Susan; Pedone, Emilia M; Leone, Marilisa

2016-11-17

The EphA2 receptor controls diverse physiological and pathological conditions and its levels are often upregulated in cancer. Targeting receptor overexpression, through modulation of endocytosis and consequent degradation, appears to be an appealing strategy for attacking tumor malignancy. In this scenario, the Sam domain of EphA2 plays a pivotal role because it is the site where protein regulators of endocytosis and stability are recruited by means of heterotypic Sam-Sam interactions. Because EphA2-Sam heterotypic complexes are largely based on electrostatic contacts, we have investigated the possibility of attacking these interactions with helical peptides enriched in charged residues. Several peptide sequences with high predicted helical propensities were designed, and detailed conformational analyses were conducted by diverse techniques including NMR, CD, and molecular dynamics (MD) simulations. Interaction studies were also performed by NMR, surface plasmon resonance (SPR), and microscale thermophoresis (MST) and led to the identification of two peptides capable of binding to the first Sam domain of Odin. These molecules represent early candidates for the generation of efficient Sam domain binders and antagonists of Sam-Sam interactions involving EphA2. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Over-expression of Eph and ephrin genes in advanced ovarian cancer: ephrin gene expression correlates with shortened survival

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Lincoln Douglas

2006-06-01

Full Text Available Abstract Background Increased expression of Eph receptor tyrosine kinases and their ephrin ligands has been implicated in tumor progression in a number of malignancies. This report describes aberrant expression of these genes in ovarian cancer, the commonest cause of death amongst gynaecological malignancies. Methods Eph and ephrin expression was determined using quantitative real time RT-PCR. Correlation of gene expression was measured using Spearman's rho statistic. Survival was analysed using log-rank analysis and (was visualised by Kaplan-Meier survival curves. Results Greater than 10 fold over-expression of EphA1 and a more modest over-expression of EphA2 were observed in partially overlapping subsets of tumors. Over-expression of EphA1 strongly correlated (r = 0.801; p Conclusion These data imply that increased levels of ephrins A1 and A5 in the presence of high expression of Ephs A1 and A2 lead to a more aggressive tumor phenotype. The known functions of Eph/ephrin signalling in cell de-adhesion and movement may explain the observed correlation of ephrin expression with poor prognosis.

Should the Equilibrium Point Hypothesis (EPH) be Considered a Scientific Theory?

OpenAIRE

Sainburg, Robert L.

2014-01-01

The purpose of this commentary is to discuss factors that limit consideration of the equilibrium point hypothesis as a scientific theory. The EPH describes control of motor neuron threshold through the variable lambda, which corresponds to a unique referent configuration for a muscle, joint, or combination of joints. One of the most compelling features of the equilibrium point hypothesis is the integration of posture and movement control into a single mechanism. While the essential core of th...

Unique structure and dynamics of the EphA5 ligand binding domain mediate its binding specificity as revealed by X-ray crystallography, NMR and MD simulations.

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Xuelu Huan

Full Text Available The 16 EphA and EphB receptors represent the largest family of receptor tyrosine kinases, and their interactions with 9 ephrin-A and ephrin-B ligands initiate bidirectional signals controlling many physiological and pathological processes. Most interactions occur between receptor and ephrins of the same class, and only EphA4 can bind all A and B ephrins. To understand the structural and dynamic principles that enable Eph receptors to utilize the same jellyroll β-sandwich fold to bind ephrins, the VAPB-MSP domain, peptides and small molecules, we have used crystallography, NMR and molecular dynamics (MD simulations to determine the first structure and dynamics of the EphA5 ligand-binding domain (LBD, which only binds ephrin-A ligands. Unexpectedly, despite being unbound, the high affinity ephrin-binding pocket of EphA5 resembles that of other Eph receptors bound to ephrins, with a helical conformation over the J-K loop and an open pocket. The openness of the pocket is further supported by NMR hydrogen/deuterium exchange data and MD simulations. Additionally, the EphA5 LBD undergoes significant picosecond-nanosecond conformational exchanges over the loops, as revealed by NMR and MD simulations, but lacks global conformational exchanges on the microsecond-millisecond time scale. This is markedly different from the EphA4 LBD, which shares 74% sequence identity and 87% homology. Consequently, the unbound EphA5 LBD appears to comprise an ensemble of open conformations that have only small variations over the loops and appear ready to bind ephrin-A ligands. These findings show how two proteins with high sequence homology and structural similarity are still able to achieve distinctive binding specificities through different dynamics, which may represent a general mechanism whereby the same protein fold can serve for different functions. Our findings also suggest that a promising strategy to design agonists/antagonists with high affinity and selectivity

Progranulin and the receptor tyrosine kinase EphA2, partners in crime?

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Chitramuthu, Babykumari; Bateman, Andrew

2016-01-01

Progranulin is a secreted protein with roles in tumorigenesis, inflammation, and neurobiology, but its signaling receptors have remained unclear. In this issue, Neill et al. (2016. J. Cell Biol. https://doi.org/10.1083/jcb.201603079) identify the tyrosine kinase EphA2 as a strong candidate for such a receptor, providing insight into progranulin and EphA2 signaling. PMID:27903608

Chimeric Antigen Receptor-Modified T Cells Redirected to EphA2 for the Immunotherapy of Non-Small Cell Lung Cancer

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Ning Li

2018-02-01

Full Text Available Erythropoietin-producing hepatocellular carcinoma A2 (EphA2 is overexpressed in more than 90% of non-small cell lung cancer (NSCLC but not significantly in normal lung tissue. It is therefore an important tumor antigen target for chimeric antigen receptors (CAR-T-based therapy in NSCLC. Here, we developed a specific CAR targeted to EphA2, and the anti-tumor effects of this CAR were investigated. A second generation CAR with co-stimulatory receptor 4-1BB targeted to EphA2 was developed. The functionality of EphA2-specific T cells in vitro was tested with flow cytometry and real-time cell electronic sensing system assays. The effect in vivo was evaluated in xenograft SCID Beige mouse model of EphA2 positive NSCLC. These EphA2-specifc T cells can cause tumor cell lysis by producing the cytokines IFN-γ when cocultured with EphA2-positive targets, and the cytotoxicity effects was specific in vitro. In vivo, the tumor signals of mice treated with EphA2-specifc T cells presented the tendency of decrease, and was much lower than the mice treated with non-transduced T cells. The anti-tumor effects of this CAR-T technology in vivo and vitro had been confirmed. Thus, EphA2-specific T-cell immunotherapy may be a promising approach for the treatment of EphA2-positive NSCLC.

Tumor Suppressor Activity of the EphB2 Receptor in Prostate Cancer

Science.gov (United States)

2008-11-01

H. (2006) Cancer Sci. 97, 1211–1216 34. Yao, V. J., Ozawa, M. G., Trepel, M., Arap, W., McDonald, D. M., and Pasqualini , R. (2005) Am. J. Pathol...and Lemay, S. (2006) Am. J. Physiol. 291, F960–F971 72. Ogawa, K., Pasqualini , R., Lindberg, R. A., Kain, R., Freeman, A. L., and Pasquale, E. B...Science 117: 2037-2049. 21. Ogawa K Pasqualini R Lindberg RA et al. (2000) The ephrin-A1 ligand and its receptor, EphA2, are expressed during tumor

Low EphA7 Expression Correlated with Lymph Node Metastasis and Poor Prognosis of Patients with Esophageal Squamous Cell Carcinoma

International Nuclear Information System (INIS)

Bai, Yu-Qin; Zhang, Jun-Yi; Bai, Chun-Ying; Xu, Xiu-E; Wu, Jian-Yi; Chen, Bo; Wu, Zhi-Yong; Wang, Shao-Hong; Shen, Jian; Shen, Jin-Hui; Yao, Xiao-Dong; Gao, Lian-Zhu; Wu, Bao; Gu, Hong-Li; Liu, Xiao-Hui; Li, Xin; Li, En-Min; Xu, Li-Yan

2015-01-01

As a member of the Eph family of receptor tyrosine kinases, EphA7 plays an important role in cancer. However, the expression and significance of Eph receptors in esophageal squamous cell carcinoma (ESCC) remain unclear. Here, we detected the expression of EphA7 by immunohistochemistry in a sample of 352 patients with ESCC, and aimed to investigate the expression status of EphA7 in ESCC and its impact on prognosis. The results showed that low EphA7 expression significantly correlated with lymph node metastases (N0: 29%; N1: 64%. p<0.001), poor degree of tumor differentiation (G1: 31%; G2: 49%; G3: 58%. p=0.009) and pTNM staging (I+II: 33%; III+IV: 58%. p<0.001). Furthermore, in a combined analysis, patients with low EphA7-expressing tumors showed a shorter overall survival than those with high expression, resulting in a five-year overall survival rate of 47.4% vs. 52.6%, respectively (p=0.016). Consequently, patients with a low EphA7 expression have poorer prognosis in ESCC compared with those manifesting high expression

Epsodic paroxysmal hemicrania with seasonal variation: case report and the EPH-cluster headache continuum hypothesis

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Veloso Germany Gonçalves

2001-01-01

Full Text Available Episodic paroxysmal hemicrania (EPH is a rare disorder characterized by frequent, daily attacks of short-lived, unilateral headache with accompanying ipsilateral autonomic features. EPH has attack periods which last weeks to months separated by remission intervals lasting months to years, however, a seasonal variation has never been reported in EPH. We report a new case of EPH with a clear seasonal pattern: a 32-year-old woman with a right-sided headache for 17 years. Pain occurred with a seasonal variation, with bouts lasting one month (usually in the first months of the year and remission periods lasting around 11 months. During these periods she had headache from three to five times per day, lasting from 15 to 30 minutes, without any particular period preference. There were no precipitating or aggravating factors. Tearing and conjunctival injection accompanied ipsilaterally the pain. Previous treatments provided no pain relief. She completely responded to indomethacin 75 mg daily. After three years, the pain recurred with longer attack duration and was just relieved with prednisone. We also propose a new hypothesis: the EPH-cluster headache continuum.

Graded and discontinuous EphA-ephrinB expression patterns in the developing auditory brainstem.

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Wallace, Matthew M; Harris, J Aaron; Brubaker, Donald Q; Klotz, Caitlyn A; Gabriele, Mark L

2016-05-01

Eph-ephrin interactions guide topographic mapping and pattern formation in a variety of systems. In contrast to other sensory pathways, their precise role in the assembly of central auditory circuits remains poorly understood. The auditory midbrain, or inferior colliculus (IC) is an intriguing structure for exploring guidance of patterned projections as adjacent subdivisions exhibit distinct organizational features. The central nucleus of the IC (CNIC) and deep aspects of its neighboring lateral cortex (LCIC, Layer 3) are tonotopically-organized and receive layered inputs from primarily downstream auditory sources. While less is known about more superficial aspects of the LCIC, its inputs are multimodal, lack a clear tonotopic order, and appear discontinuous, terminating in modular, patch/matrix-like distributions. Here we utilize X-Gal staining approaches in lacZ mutant mice (ephrin-B2, -B3, and EphA4) to reveal EphA-ephrinB expression patterns in the nascent IC during the period of projection shaping that precedes hearing onset. We also report early postnatal protein expression in the cochlear nuclei, the superior olivary complex, the nuclei of the lateral lemniscus, and relevant midline structures. Continuous ephrin-B2 and EphA4 expression gradients exist along frequency axes of the CNIC and LCIC Layer 3. In contrast, more superficial LCIC localization is not graded, but confined to a series of discrete ephrin-B2 and EphA4-positive Layer 2 modules. While heavily expressed in the midline, much of the auditory brainstem is devoid of ephrin-B3, including the CNIC, LCIC Layer 2 modular fields, the dorsal nucleus of the lateral lemniscus (DNLL), as well as much of the superior olivary complex and cochlear nuclei. Ephrin-B3 LCIC expression appears complementary to that of ephrin-B2 and EphA4, with protein most concentrated in presumptive extramodular zones. Described tonotopic gradients and seemingly complementary modular/extramodular patterns suggest Eph

After repeated division, bone marrow stromal cells express inhibitory factors with osteogenic capabilities, and EphA5 is a primary candidate.

Science.gov (United States)

Yamada, Tsuyoshi; Yuasa, Masato; Masaoka, Tomokazu; Taniyama, Takashi; Maehara, Hidetsugu; Torigoe, Ichiro; Yoshii, Toshitaka; Shinomiya, Kenichi; Okawa, Atsushi; Sotome, Shinichi

2013-12-01

The differentiation capability of human bone marrow stromal cells (hBMSCs) is thought to deteriorate over multiple doubling processes. To clarify the deterioration mechanisms, the multilineage differentiation capabilities of short- and long-term passaged BMSCs were compared. Predictably, long-term passaged BMSCs showed reduced differentiation capacities compared to short-term passaged cells. Furthermore, a non-human primate heterotopic bone formation model demonstrated that long-term passaged BMSCs have bone formation capabilities but also exert inhibitory effects on bone formation. This finding indicated that long-term passaged BMSCs express higher levels of inhibitory factors than short-term passaged BMSCs do. Co-culture assays of short- and long-term passaged BMSCs suggested that the inhibitory signals required cell-cell contact and would therefore be expressed on the cell membrane. A microarray analysis of BMSCs identified ephrin type-A receptor 5 (EphA5) as an inhibitory factor candidate. Quantitative PCR revealed that among all members of the ephrin and Eph receptor families, only the expression of EphA5 was increased by BMSC proliferation. A gene knockdown analysis using siRNAs demonstrated that knockdown of EphA5 gene expression in long-term passaged BMSCs led to an increase in ALP mRNA expression. These results indicate that EphA5 may be a negative regulator of bone formation. A better understanding of the roles of the ephrin and Eph receptor families in hBMSCs may lead to alternative approaches for manipulating hBMSC fate. In addition, this avenue of discovery may provide new therapeutic targets and quality-control markers of the osteogenic differentiation capabilities of hBMSCs. © 2013.

Expression of Eph receptor tyrosine kinases and their ligands in human Granulosa lutein cells and human umbilical vein endothelial cells.

Science.gov (United States)

Xu, Y; Zagoura, D; Keck, C; Pietrowski, D

2006-11-01

Corpus luteum development is regulated by gonadotropins and accompanied by extremely rapid vascularization of the avascular granulosa cell compartiment by endothelial cells (EC). The proliferation of Granulosa cells (GC) and EC is a complex interplay and takes place in a spatially and temporarily coordinated manner. The erythropoietin-producing hepatoma amplified sequence (Eph) receptors and their ligands-the ephrins- are a recently detected family of membrane located protein tyrosine kinases which play a crucial role in the growth and development of nerve and blood vessel network. We report about the mRNA expression pattern of Ephs and their ligands in human GC, in human EC, and in carcinoma cell lines OvCar-3 and Hela. The mRNA of EphA4, EphA7, ephrinA4, ephrinB1 and ephrinB2 was detected in GC and EC, while EphA2 was expressed only in GC. The expression of various Ephs and ephrins did not change in GC after stimulation with human chorion gonadotropin. Our study analyzes for the first time the expression of the complete human Eph/ephriny-system in GC and in EC. The remarkable similarity between these two cell types supports the theory of a functional relationship of EC and GC. In addition, it was shown that hCG is not a major determinant of Eph/ephrin regulation in GC.

The Sam-Sam interaction between Ship2 and the EphA2 receptor: design and analysis of peptide inhibitors.

Science.gov (United States)

Mercurio, Flavia Anna; Di Natale, Concetta; Pirone, Luciano; Iannitti, Roberta; Marasco, Daniela; Pedone, Emilia Maria; Palumbo, Rosanna; Leone, Marilisa

2017-12-12

The lipid phosphatase Ship2 represents a drug discovery target for the treatment of different diseases, including cancer. Its C-terminal sterile alpha motif domain (Ship2-Sam) associates with the Sam domain from the EphA2 receptor (EphA2-Sam). This interaction is expected to mainly induce pro-oncogenic effects in cells therefore, inhibition of the Ship2-Sam/EphA2-Sam complex may represent an innovative route to discover anti-cancer therapeutics. In the present work, we designed and analyzed several peptide sequences encompassing the interaction interface of EphA2-Sam for Ship2-Sam. Peptide conformational analyses and interaction assays with Ship2-Sam conducted through diverse techniques (CD, NMR, SPR and MST), identified a positively charged penta-amino acid native motif in EphA2-Sam, that once repeated three times in tandem, binds Ship2-Sam. NMR experiments show that the peptide targets the negatively charged binding site of Ship2-Sam for EphA2-Sam. Preliminary in vitro cell-based assays indicate that -at 50 µM concentration- it induces necrosis of PC-3 prostate cancer cells with more cytotoxic effect on cancer cells than on normal dermal fibroblasts. This work represents a pioneering study that opens further opportunities for the development of inhibitors of the Ship2-Sam/EphA2-Sam complex for therapeutic applications.

Combination of Dll4/Notch and Ephrin-B2/EphB4 targeted therapy is highly effective in disrupting tumor angiogenesis

International Nuclear Information System (INIS)

Djokovic, Dusan; Gill, Parkash S; Duarte, Antonio; Trindade, Alexandre; Gigante, Joana; Badenes, Marina; Silva, Lilliana; Liu, Ren; Li, Xiuqing; Gong, Ming; Krasnoperov, Valery

2010-01-01

Dll4/Notch and Ephrin-B2/EphB4 pathways play critical roles in tumor vessel development and maturation. This study evaluates the efficacy of the inhibition of both signaling pathways, alone and in combination, in reducing the growth of an autochthonous mouse tumor and assesses potential adverse effects. We used the transgenic RIP1-Tag2 tumor model to study the effects of 1) inhibition of Dll4/Notch by either Dll4 allelic deletion or use of a soluble extracellular Dll4 (sDll4), 2) inhibition of Ephrin-B2/EphB4 signaling by a soluble extracellular EphB4 fused to albumin (sEphB4-Alb), and 3) inhibition of both pathways by sEphB4-Alb combined with either Dll4 allelic deletion or sDll4. To investigate adverse effects, we used inducible endothelial-specific Dll4 knock-out mice, treated with sEphB4-Alb, and carried out histopathological analysis. Dll4 allele deletion or soluble Dll4 treatment resulted in increased tumor vessel density, reduced mural cell recruitment and vessel perfusion which resulted in reduced tumor size. The soluble EphB4 instead reduced vessel density and vessel perfusion, leading to reduction of tumor size. Greater efficacy was observed when sEphB4-Alb was combined with either Dll4 allele deletion or sDll4 in regards to tumor size, vessel perfusion and mural cell recruitment. Induced endothelial specific Dll4 loss-of-function caused hepatic vascular alterations, which were prevented by concomitant sEphB4-Alb treatment. Combination targeting of Dll4/Notch and Ephrin-B2/EphB4 has potential for clinical investigation, providing cumulative efficacy and increased safety over Dll4/Notch inhibition alone

EphA2 is a biomarker of hMSCs derived from human placenta and umbilical cord

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Shih-Pei Shen

2015-12-01

Conclusion: EphA2 can be used to distinguish and isolate MSCs from a primary culture of placenta-derived cells. EphA2-sorted MSCs exhibited superior responsiveness to TNF-α signaling in an inflammatory environment compared with unsorted MSCs or MSC-like cells.

Shorter duration of non-rapid eye movement sleep slow waves in EphA4 knockout mice.

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Freyburger, Marlène; Poirier, Gaétan; Carrier, Julie; Mongrain, Valérie

2017-10-01

Slow waves occurring during non-rapid eye movement sleep have been associated with neurobehavioural performance and memory. In addition, the duration of previous wakefulness and sleep impacts characteristics of these slow waves. However, molecular mechanisms regulating the dynamics of slow-wave characteristics remain poorly understood. The EphA4 receptor regulates glutamatergic transmission and synaptic plasticity, which have both been linked to sleep slow waves. To investigate if EphA4 regulates slow-wave characteristics during non-rapid eye movement sleep, we compared individual parameters of slow waves between EphA4 knockout mice and wild-type littermates under baseline conditions and after a 6-h sleep deprivation. We observed that, compared with wild-type mice, knockout mice display a shorter duration of positive and negative phases of slow waves under baseline conditions and after sleep deprivation. However, the mutation did not change slow-wave density, amplitude and slope, and did not affect the sleep deprivation-dependent changes in slow-wave characteristics, suggesting that EphA4 is not involved in the response to elevated sleep pressure. Our present findings suggest a role for EphA4 in shaping cortical oscillations during sleep that is independent from sleep need. © 2017 European Sleep Research Society.

[The influence of EphA2 overexpression on proliferation and apoptosis of human lens epithelial cells exposed to high-concentration dexamethasone in vitro].

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Ma, C X; Zheng, G Y

2018-02-11

Objective: To construct lentiviral-mediated EphA2 overexpression vectors, transfect them into human lens epithelial cells (HLE-B3) in vitro , and investigate the effect of EphA2 gene overexpression on the proliferation and apoptosis of HLE-B3 exposed to high-concentration dexamethasone. Methods: Experimental Study. The pCDH-CMV- MCS-EF1-RFP plasmid was set up by the digestion of NOTⅠand XbaⅠ double restriction enzyme and ligation of CE ligase, and then the plasmid was transformed into DH10B cells. Seven clons were picked for enzymatic digestion and the clons with correct results were chosen for sequencing. The 293 T/17 cells were co-transfected with the pCDH-CMV-MCS-EF1-RFP-EphA2 and the packaging mixture by Lipofectamine 2000. At different multiplicities of infection (MOI=20, 50, 100, and 200) after 72-hour infection, we observed the expression of RFP and morphological changes of HLE-B3 by an inverted fluorescence microscope, and calculated the transfection efficiency through the flow cytometry. EphA2 protein expression was detected by Western blot. The following experiments were divided into four groups: normal control group (group A), EphA2 overexpression vector transfection group (group B), HLE-B3 cells exposed to dexamethasone group (group C) and EphA2 overexpression vector transfection HLE-B3 cells exposed to dexamethasone group (group D). Statistical analysis method was single factor or two factors variance analysis. Cell survival rate was detected by the Cell Counting Kit-8 assay. Cell apoptosis index was detected by Tunel. Results: Restriction enzyme digestion and sequencing indicated that EphA2 cDNA fragment was successfully inserted in the vector. The infection efficiency was up to 38.6%±3.9%, 49.2%±4.2%, 79.5%±5.5% and 80.2%±6.0% when the MOI was 20, 50, 100 and 200, respectively. There was statistically significant difference ( F= 2 600.8, P= 0.001) among the four groups and between any two groups except between the MOI=100 group and MOI=200

EphB1 as a Novel Drug Target to Combat Pain and Addiction

Science.gov (United States)

2017-09-01

AWARD NUMBER: W81XWH-14-1-0220 TITLE: EphB1 as a Novel Drug Target to Combat Pain and Addiction PRINCIPAL INVESTIGATOR: Mark Henkemeyer...as a Novel Drug Target to Combat Pain and Ad 5a. CONTRACT NUMBER EphB1 as a Novel Drug Target to Combat Pain and Addiction 5b. GRANT NUMBER W81XWH...neuronal and has functions in vascular endothelial cells. 6. We have also carried out computational analysis of potantial docking/binding of chemical

Change in the balance of excitatory and inhibitory midline fiber crossing as an explanation for the hopping phenotype in EphA4 knockout mice

DEFF Research Database (Denmark)

Restrepo, Carlos E.; Margaryan, Gayane; Borgius, Lotta

2011-01-01

Neuronal networks in the spinal cord termed central pattern generators (CPGs) are responsible for the generation of rhythmic movements, such as walking. The axon guidance molecule EphA4 has been suggested to play a role in the configuration of spinal CPG networks in mammals. In EphA4 knockout (Eph...... compared with EphA4 lacZ/+ mice. These results show that the hopping phenotype is the result of a change in the balance between excitatory and inhibitory signals across the midline and that EphA4-positive neurons play an essential role in the mammalian CPG....

EphrinA4 mimetic peptide targeted to EphA binding site impairs the formation of long-term fear memory in lateral amygdala.

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Dines, M; Lamprecht, R

2014-09-30

Fear conditioning leads to long-term fear memory formation and is a model for studying fear-related psychopathologies conditions such as phobias and posttraumatic stress disorder. Long-term fear memory formation is believed to involve alterations of synaptic efficacy mediated by changes in synaptic transmission and morphology in lateral amygdala (LA). EphrinA4 and its cognate Eph receptors are intimately involved in regulating neuronal morphogenesis, synaptic transmission and plasticity. To assess possible roles of ephrinA4 in fear memory formation we designed and used a specific inhibitory ephrinA4 mimetic peptide (pep-ephrinA4) targeted to EphA binding site. We show that this peptide, composed of the ephrinA4 binding domain, interacts with EphA4 and inhibits ephrinA4-induced phosphorylation of EphA4. Microinjection of the pep-ephrinA4 into rat LA 30 min before training impaired long- but not short-term fear conditioning memory. Microinjection of a control peptide derived from a nonbinding E helix site of ephrinA4, that does not interact with EphA, had no effect on fear memory formation. Microinjection of pep-ephrinA4 into areas adjacent to the amygdala had no effect on fear memory. Acute systemic administration of pep-ephrinA4 1 h after training also impaired long-term fear conditioning memory formation. These results demonstrate that ephrinA4 binding sites in LA are essential for long-term fear memory formation. Moreover, our research shows that ephrinA4 binding sites may serve as a target for pharmacological treatment of fear and anxiety disorders.

Crystal structure of the EphA4 protein tyrosine kinase domain in the apo-and dasantinib-bound state

NARCIS (Netherlands)

Farenc, C; Celie, C; Tensen, P.H.N; de Esch, I.J.P.; Siegal, C.P.

2011-01-01

The Eph family of receptor tyrosine kinases regulates diverse cellular processes while the over-expression of a member of this family, EphA4, has been reported in a variety of malignant carcinomas. To gain insight into molecular mechanisms and to facilitate structure-based inhibitor design, we

Structural investigation of a C-terminal EphA2 receptor mutant: Does mutation affect the structure and interaction properties of the Sam domain?

Science.gov (United States)

Mercurio, Flavia A; Costantini, Susan; Di Natale, Concetta; Pirone, Luciano; Guariniello, Stefano; Scognamiglio, Pasqualina L; Marasco, Daniela; Pedone, Emilia M; Leone, Marilisa

2017-09-01

Ephrin A2 receptor (EphA2) plays a key role in cancer, it is up-regulated in several types of tumors and the process of ligand-induced receptor endocytosis, followed by degradation, is considered as a potential path to diminish tumor malignancy. Protein modulators of this mechanism are recruited at the cytosolic Sterile alpha motif (Sam) domain of EphA2 (EphA2-Sam) through heterotypic Sam-Sam associations. These interactions engage the C-terminal helix of EphA2 and close loop regions (the so called End Helix side). In addition, several studies report on destabilizing mutations in EphA2 related to cataract formation and located in/or close to the Sam domain. Herein, we analyzed from a structural point of view, one of these mutants characterized by the insertion of a novel 39 residue long polypeptide at the C-terminus of EphA2-Sam. A 3D structural model was built by computational methods and revealed partial disorder in the acquired C-terminal tail and a few residues participating in an α-helix and two short β-strands. We investigated by CD and NMR studies the conformational properties in solution of two peptides encompassing the whole C-terminal tail and its predicted helical region, respectively. NMR binding experiments demonstrated that these peptides do not interact relevantly with either EphA2-Sam or its interactor Ship2-Sam. Molecular dynamics (MD) simulations further indicated that the EphA2 mutant could be represented only through a conformational ensemble and that the C-terminal tail should not largely wrap the EphA2-Sam End-Helix interface and affect binding to other Sam domains. Copyright © 2017 Elsevier B.V. All rights reserved.

Eph receptors and ephrins in neuron-astrocyte communication at synapses.

Science.gov (United States)

Murai, Keith K; Pasquale, Elena B

2011-11-01

Neuron-glia communication is essential for regulating the properties of synaptic connections in the brain. Astrocytes, in particular, play a critical and complex role in synapse development, maintenance, and plasticity. Likewise, neurons reciprocally influence astrocyte physiology. However, the molecular signaling events that enable astrocytes and neurons to effectively communicate with each other are only partially defined. Recent findings have revealed that Eph receptor tyrosine kinases and ephrins play an important role in contact-dependent neuron-glia communication at synapses. Upon binding, these two families of cell surface-associated proteins trigger bidirectional signaling events that regulate the structural and physiological properties of both neurons and astrocytes. This review will focus on the emerging role of Eph receptors and ephrins in neuron-astrocyte interaction at synapses and discuss implications for synaptic plasticity, behavior, and disease. Copyright © 2011 Wiley-Liss, Inc.

Eph regulates dorsoventral asymmetry of the notochord plate and convergent extension-mediated notochord formation.

Science.gov (United States)

Oda-Ishii, Izumi; Ishii, Yasuo; Mikawa, Takashi

2010-10-29

The notochord is a signaling center required for the patterning of the vertebrate embryonic midline, however, the molecular and cellular mechanisms involved in the formation of this essential embryonic tissue remain unclear. The urochordate Ciona intestinalis develops a simple notochord from 40 specific postmitotic mesodermal cells. The precursors intercalate mediolaterally and establish a single array of disk-shaped notochord cells along the midline. However, the role that notochord precursor polarization, particularly along the dorsoventral axis, plays in this morphogenetic process remains poorly understood. Here we show that the notochord preferentially accumulates an apical cell polarity marker, aPKC, ventrally and a basement membrane marker, laminin, dorsally. This asymmetric accumulation of apicobasal cell polarity markers along the embryonic dorsoventral axis was sustained in notochord precursors during convergence and extension. Further, of several members of the Eph gene family implicated in cellular and tissue morphogenesis, only Ci-Eph4 was predominantly expressed in the notochord throughout cell intercalation. Introduction of a dominant-negative Ci-Eph4 to notochord precursors diminished asymmetric accumulation of apicobasal cell polarity markers, leading to defective intercalation. In contrast, misexpression of a dominant-negative mutant of a planar cell polarity gene Dishevelled preserved asymmetric accumulation of aPKC and laminin in notochord precursors, although their intercalation was incomplete. Our data support a model in which in ascidian embryos Eph-dependent dorsoventral polarity of notochord precursors plays a crucial role in mediolateral cell intercalation and is required for proper notochord morphogenesis.

A Novel EphA2 Inhibitor Exerts Beneficial Effects in PI-IBS in Vivo and in Vitro Models via Nrf2 and NF-κB Signaling Pathways

Directory of Open Access Journals (Sweden)

Li Zeng

2018-03-01

Full Text Available Though the detailed pathological mechanism of post-infectious irritable bowel syndrome (PI-IBS remains unclear, accumulating evidence indicates that oxidative stress and inflammation are implicated in the process of PI-IBS. Oxidative stress and inflammation are regulated by Nrf2 and NF-κB signaling pathways, respectively. EphA2, a member of Eph receptor family, promotes oxidative stress and inflammatory responses via regulation of Nrf2 and NF-κB signaling pathways in various types of human diseases. Understanding the mechanisms by which EphA2 regulate oxidative stress and inflammation in PI-IBS is important for the development of new strategies to treat PI-IBS. However, the effects of ALW-II-41-27, a novel EphA2 inhibitor on PI-IBS and the underlying molecular mechanisms have never been studied. In the present study, we showed that ALW-II-41-27 decreased gastrointestinal motility and abdominal withdrawal reflex (AWR scores, markedly reduced the levels of oxidative stress markers [4-hydroxy-2-nonenal (4-HNE, protein carbonyl, and 8-hydroxy-2-de-axyguanine (8-OHdG] and proinflammatory cytokines (TNF-α, IL-6, IL-17, and ICAM-1, and remarkably increased the level of anti-inflammatory cytokine (IL-10 in serum and colon of Trichinella spiralis-infected mice. Moreover, ALW-II-41-27 was effective in suppressing oxidative stress and inflammation in LPS-treated NCM460 colonic cells. Treatment of ALW-II-41-27 reversed the activation of NF-κB and inactivation of Nrf2 in LPS-treated NCM460 cells. Importantly, these protective effects of ALW-II-41-27 were partially inhibited by EphA2 KO and abolished by EphA2 overexpression. In conclusion, EphA2 may represent a promising therapeutic target for patients with PI-IBS and ALW-II-41-27 might function as a novel therapeutic agent for PI-IBS.

EphA4 Regulates the Balance between Self-Renewal and Differentiation of Radial Glial Cells and Intermediate Neuronal Precursors in Cooperation with FGF Signaling.

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Qingfa Chen

Full Text Available In mouse cerebral corticogenesis, neurons are generated from radial glial cells (RGCs or from their immediate progeny, intermediate neuronal precursors (INPs. The balance between self-renewal of these neuronal precursors and specification of cell fate is critical for proper cortical development, but the signaling mechanisms that regulate this progression are poorly understood. EphA4, a member of the receptor tyrosine kinase superfamily, is expressed in RGCs during embryogenesis. To illuminate the function of EphA4 in RGC cell fate determination during early corticogenesis, we deleted Epha4 in cortical cells at E11.5 or E13.5. Loss of EphA4 at both stages led to precocious in vivo RGC differentiation toward neurogenesis. Cortical cells isolated at E14.5 and E15.5 from both deletion mutants showed reduced capacity for neurosphere formation with greater differentiation toward neurons. They also exhibited lower phosphorylation of ERK and FRS2α in the presence of FGF. The size of the cerebral cortex at P0 was smaller than that of controls when Epha4 was deleted at E11.5 but not when it was deleted at E13.5, although the cortical layers were formed normally in both mutants. The number of PAX6-positive RGCs decreased at later developmental stages only in the E11.5 Epha4 deletion mutant. These results suggest that EphA4, in cooperation with an FGF signal, contributes to the maintenance of RGC self-renewal and repression of RGC differentiation through the neuronal lineage. This function of EphA4 is especially critical and uncompensated in early stages of corticogenesis, and thus deletion at E11.5 reduces the size of the neonatal cortex.

Blocking the Interaction between EphB2 and ADDLs by a Small Peptide Rescues Impaired Synaptic Plasticity and Memory Deficits in a Mouse Model of Alzheimer's Disease.

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Shi, Xiao-Dong; Sun, Kai; Hu, Rui; Liu, Xiao-Ya; Hu, Qiu-Mei; Sun, Xiao-Yu; Yao, Bin; Sun, Nan; Hao, Jing-Ru; Wei, Pan; Han, Yuan; Gao, Can

2016-11-23

Soluble amyloid-β (Aβ) oligomers, also known as Aβ-derived diffusible ligands (ADDLs), are thought to be the key pathogenic factor in Alzheimer's disease (AD), but there is still no effective treatment for preventing or reversing the progression of the disease. Targeting NMDA receptor trafficking and regulation is a new strategy for early treatment of AD. Aβ oligomers have been found to bind to the fibronectin (FN) type III repeat domain of EphB2 to trigger EphB2 degradation, thereby impairing the normal functioning of NMDA receptors and resulting in cognitive deficits. Here, we identified for the first time the interaction sites of the EphB2 FN domain with ADDLs by applying the peptide array method to design and synthesize four candidate peptides (Pep21, Pep25, Pep32, and Pep63) that might be able to block the EphB2-ADDL interaction. Among them, Pep63 was found to be the most effective at inhibiting the binding between EphB2 and ADDLs. We found that Pep63 not only rescued the ADDL-induced depletion of EphB2- and GluN2B-containing NMDA receptors from the neuronal surface in cultured hippocampal neurons, but also improved impaired memory deficits in APPswe/PS1dE9 (APP/PS1) transgenic mice and the phosphorylation and surface expression of GluN2B-containing NMDA receptors in cultures. Together, these results suggest that blocking the EphB2-ADDL interaction by small interfering peptides may be a promising strategy for AD treatment. Alzheimer's disease (AD) is an age-dependent neurodegenerative disorder and amyloid β-derived diffusible ligands (ADDLs) play a key role in triggering the early cognitive deficits that constitute AD. ADDLs may bind EphB2 and alter NMDA receptor trafficking and synaptic plasticity. Here, we identified the interaction sites of the EphB2 FN domain with ADDLs for the first time to develop a small (10 aa) peptide (Pep63) capable of blocking the EphB2-ADDL interaction. We found that Pep63 not only rescued the ADDL-induced depletion of EphB2

Aberrant expression of the tyrosine kinase receptor EphA4 and the transcription factor twist in Sézary syndrome identified by gene expression analysis.

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van Doorn, Remco; Dijkman, Remco; Vermeer, Maarten H; Out-Luiting, Jacoba J; van der Raaij-Helmer, Elisabeth M H; Willemze, Rein; Tensen, Cornelis P

2004-08-15

Sézary syndrome (Sz) is a malignancy of CD4+ memory skin-homing T cells and presents with erythroderma, lymphadenopathy, and peripheral blood involvement. To gain more insight into the molecular features of Sz, oligonucleotide array analysis was performed comparing gene expression patterns of CD4+ T cells from peripheral blood of patients with Sz with those of patients with erythroderma secondary to dermatitis and healthy controls. Using unsupervised hierarchical clustering gene, expression patterns of T cells from patients with Sz were classified separately from those of benign T cells. One hundred twenty-three genes were identified as significantly differentially expressed and had an average fold change exceeding 2. T cells from patients with Sz demonstrated decreased expression of the following hematopoietic malignancy-linked tumor suppressor genes: TGF-beta receptor II, Mxi1, Riz1, CREB-binding protein, BCL11a, STAT4, and Forkhead Box O1A. Moreover, the tyrosine kinase receptor EphA4 and the potentially oncogenic transcription factor Twist were highly and selectively expressed in T cells of patients with Sz. High expression of EphA4 and Twist was also observed in lesional skin biopsy specimens of a subset of patients with cutaneous T cell lymphomas related to Sz, whereas their expression was nearly undetectable in benign T cells or in skin lesions of patients with inflammatory dermatoses. Detection of EphA4 and Twist may be used in the molecular diagnosis of Sz and related cutaneous T-cell lymphomas. Furthermore, the membrane-bound EphA4 receptor may serve as a target for directed therapeutic intervention.

[Concentration of cysteine proteinase inhibitors in urine, amniotic fluid and serum from women in pregnancy complicated by EPH-gestosis].

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Karmowski, A; Sobiech, K A; Kertyńska, I; Terpiłowski, L; Słowińska-Lisowska, M; Pałczyński, B; Malik, B

2000-10-01

Cysteine proteinase inhibitors (IPC) concentration was measured by the modified Barrett method using papaine in urine, amniotic fluid and serum obtained from the healthy labored women and from labored women in pregnancy complicated by EPH-gestosis. It was noticed the statistically significant increase in the IPC concentration in the material from the pregnant women with EPH-gestosis comparing to the women, which pregnancy had the physiologically normal course.

Adenoviruses using the cancer marker EphA2 as a receptor in vitro and in vivo by genetic ligand insertion into different capsid scaffolds.

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Michael Behr

Full Text Available Adenoviral gene therapy and oncolysis would critically benefit from targeted cell entry by genetically modified capsids. This requires both the ablation of native adenovirus tropism and the identification of ligands that remain functional in virus context. Here, we establish cell type-specific entry of HAdV-5-based vectors by genetic ligand insertion into a chimeric fiber with shaft and knob domains of the short HAdV-41 fiber (Ad5T/41sSK. This fiber format was reported to ablate transduction in vitro and biodistribution to the liver in vivo. We show that the YSA peptide, binding to the pan-cancer marker EphA2, can be inserted into three positions of the chimeric fiber, resulting in strong transduction of EphA2-positive but not EphA2-negative cells of human melanoma biopsies and of tumor xenografts after intratumoral injection. Transduction was blocked by soluble YSA peptide and restored for EphA2-negative cells after recombinant EphA2 expression. The YSA peptide could also be inserted into three positions of a CAR binding-ablated HAdV-5 fiber enabling specific transduction; however, the Ad5T/41sSK format was superior in vivo. In conclusion, we establish an adenovirus capsid facilitating functional insertion of targeting peptides and a novel adenovirus using the tumor marker EphA2 as receptor with high potential for cancer gene therapy and viral oncolysis.

Adenoviruses Using the Cancer Marker EphA2 as a Receptor In Vitro and In Vivo by Genetic Ligand Insertion into Different Capsid Scaffolds

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Behr, Michael; Kaufmann, Johanna K.; Ketzer, Patrick; Engelhardt, Sarah; Mück-Häusl, Martin; Okun, Pamela M.; Petersen, Gabriele; Neipel, Frank; Hassel, Jessica C.; Ehrhardt, Anja; Enk, Alexander H.; Nettelbeck, Dirk M.

2014-01-01

Adenoviral gene therapy and oncolysis would critically benefit from targeted cell entry by genetically modified capsids. This requires both the ablation of native adenovirus tropism and the identification of ligands that remain functional in virus context. Here, we establish cell type-specific entry of HAdV-5-based vectors by genetic ligand insertion into a chimeric fiber with shaft and knob domains of the short HAdV-41 fiber (Ad5T/41sSK). This fiber format was reported to ablate transduction in vitro and biodistribution to the liver in vivo. We show that the YSA peptide, binding to the pan-cancer marker EphA2, can be inserted into three positions of the chimeric fiber, resulting in strong transduction of EphA2-positive but not EphA2-negative cells of human melanoma biopsies and of tumor xenografts after intratumoral injection. Transduction was blocked by soluble YSA peptide and restored for EphA2-negative cells after recombinant EphA2 expression. The YSA peptide could also be inserted into three positions of a CAR binding-ablated HAdV-5 fiber enabling specific transduction; however, the Ad5T/41sSK format was superior in vivo. In conclusion, we establish an adenovirus capsid facilitating functional insertion of targeting peptides and a novel adenovirus using the tumor marker EphA2 as receptor with high potential for cancer gene therapy and viral oncolysis. PMID:24760010

A Novel EphA4 Based Small Molecule Based Therapeutic Strategy for Prevention and Treatment of Post Traumatic Osteoarthritis

Science.gov (United States)

2016-09-01

appropriate personnel prior to the initiation of the project. o Subtask 1.1: To obtain the required regulatory review and approval for use of animal ...EphA4 in these cells un-stimulated and largely nonfunctional. Accordingly, we salvaged the knee joints from the carcasses of the euthanized EphA4 null...mice and WT littermates, which could be used for isolation of synoviocytes or articular chondrocytes after the carcasses were discarded from the other

Phenotype of V2-derived interneurons and their relationship to the axon guidance molecule EphA4 in the developing mouse spinal cord

DEFF Research Database (Denmark)

Lundfald, Line; Restrepo, C. Ernesto; Butt, Simon J B

2007-01-01

, we demonstrated that a large proportion of V2 interneurons expressed the axon guidance molecule EphA4, a molecule previously shown to be important for correct organization of locomotor networks. We also showed that V2 interneurons and motor neurons alone did not account for all EphA4-expressing...

Regional expression and ultrastructural localization of EphA7 in the hippocampus and cerebellum of adult rat.

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Amegandjin, Clara A; Jammow, Wafaa; Laforest, Sylvie; Riad, Mustapha; Baharnoori, Moogeh; Badeaux, Frédérique; DesGroseillers, Luc; Murai, Keith K; Pasquale, Elena B; Drolet, Guy; Doucet, Guy

2016-08-15

EphA7 is expressed in the adult central nervous system (CNS), where its roles are yet poorly defined. We mapped its distribution using in situ hybridization (ISH) and immunohistochemistry (IHC) combined with light (LM) and electron microscopy (EM) in adult rat and mouse brain. The strongest ISH signal was in the hippocampal pyramidal and granule cell layers. Moderate levels were detected in habenula, striatum, amygdala, the cingulate, piriform and entorhinal cortex, and in cerebellum, notably the Purkinje cell layer. The IHC signal distribution was consistent with ISH results, with transport of the protein to processes, as exemplified in the hippocampal neuropil layers and weakly stained pyramidal cell layers. In contrast, in the cerebellum, the Purkinje cell bodies were the most strongly immunolabeled elements. EM localized the cell surface-expression of EphA7 essentially in postsynaptic densities (PSDs) of dendritic spines and shafts, and on some astrocytic leaflets, in both hippocampus and cerebellum. Perikaryal and dendritic labeling was mostly intracellular, associated with the synthetic and trafficking machineries. Immunopositive vesicles were also observed in axons and axon terminals. Quantitative analysis in EM showed significant differences in the frequency of labeled elements between regions. Notably, labeled dendrites were ∼3-5 times less frequent in cerebellum than in hippocampus, but they were individually endowed with ∼10-40 times higher frequencies of PSDs, on their shafts and spines. The cell surface localization of EphA7, being preferentially in PSDs, and in perisynaptic astrocytic leaflets, provides morphologic evidence that EphA7 plays key roles in adult CNS synaptic maintenance, plasticity, or function. J. Comp. Neurol. 524:2462-2478, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Expressions of EphA2 and EphrinA-1 in early squamous cell cervical carcinomas and their relation to prognosis

OpenAIRE

Holm, Ruth; de Putte, Gregg Van; Suo, Zhenhe; Lie, A Kathrine; Kristensen, Gunnar B

2008-01-01

By using immunohistochemistry we investigated the expression of EphA2 and EphrinA-1 in 217 early squamous cell cervical carcinomas and examine their prognostic relevance. For EphA2 expression, 21 tumors (10%) showed negative, 108 (50%) weak positive, 69 (32%) moderate positive and 19 (9%) strong positive, whereas for EphrinA-1 expression, 33 tumors (15%) showed negative, 91 (42%) weak positive, 67 (31%) moderate positive and 26 (12%) strong positive. In univariate analysis high expression (st...

Convergent Evolution of Head Crests in Two Domesticated Columbids Is Associated with Different Missense Mutations in EphB2

Science.gov (United States)

Vickrey, Anna I.; Domyan, Eric T.; Horvath, Martin P.; Shapiro, Michael D.

2015-01-01

Head crests are important display structures in wild bird species and are also common in domesticated lineages. Many breeds of domestic rock pigeon (Columba livia) have crests of reversed occipital feathers, and this recessive trait is associated with a nonsynonymous coding mutation in the intracellular kinase domain of EphB2 (Ephrin receptor B2). The domestic ringneck dove (Streptopelia risoria) also has a recessive crested morph with reversed occipital feathers, and interspecific crosses between crested doves and pigeons produce crested offspring, suggesting a similar genetic basis for this trait in both species. We therefore investigated EphB2 as a candidate for the head crest phenotype of ringneck doves and identified a nonsynonymous coding mutation in the intracellular kinase domain that is significantly associated with the crested morph. This mutation is over 100 amino acid positions away from the crest mutation found in rock pigeons, yet both mutations are predicted to negatively affect the function of ATP-binding pocket. Furthermore, bacterial toxicity assays suggest that “crest” mutations in both species severely impact kinase activity. We conclude that head crests are associated with different mutations in the same functional domain of the same gene in two different columbid species, thereby representing striking evolutionary convergence in morphology and molecules. PMID:26104009

Fully-human Monoclonal Antibodies Against Human EphrinB2 and EphB4 | NCI Technology Transfer Center | TTC

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The National Cancer Institute's Cancer and Inflammation Program is seeking statements of capability or interest from parties interested in licensing fully-human monoclonal antibodies against human EphrinB2 and EphB4.

The case for an internal dynamics model versus equilibrium point control in human movement.

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Hinder, Mark R; Milner, Theodore E

2003-06-15

The equilibrium point hypothesis (EPH) was conceived as a means whereby the central nervous system could control limb movements by a relatively simple shift in equilibrium position without the need to explicitly compensate for task dynamics. Many recent studies have questioned this view with results that suggest the formation of an internal dynamics model of the specific task. However, supporters of the EPH have argued that these results are not incompatible with the EPH and that there is no reason to abandon it. In this study, we have tested one of the fundamental predictions of the EPH, namely, equifinality. Subjects learned to perform goal-directed wrist flexion movements while a motor provided assistance in proportion to the instantaneous velocity. It was found that the subjects stopped short of the target on the trials where the magnitude of the assistance was randomly decreased, compared to the preceding control trials (P = 0.003), i.e. equifinality was not achieved. This is contrary to the EPH, which predicts that final position should not be affected by external loads that depend purely on velocity. However, such effects are entirely consistent with predictions based on the formation of an internal dynamics model.

Spinal glutamatergic neurons defined by EphA4 signaling are essential components of normal locomotor circuits

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Borgius, Lotta; Nishimaru, Hiroshi; Caldeira, Vanessa

2014-01-01

EphA4 signaling is essential for the spatiotemporal organization of neuronal circuit formation. In mice, deletion of this signaling pathway causes aberrant midline crossing of axons from both brain and spinal neurons and the complete knock-outs (KOs) exhibit a pronounced change in motor behavior...

Can a Proper T-Cell Development Occur in an Altered Thymic Epithelium? Lessons From EphB-Deficient Thymi

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Juan José Muñoz

2018-04-01

Full Text Available For a long time, the effects of distinct Eph tyrosine kinase receptors and their ligands, ephrins on the structure, immunophenotype, and development of thymus and their main cell components, thymocytes (T and thymic epithelial cells (TECs, have been studied. In recent years, the thymic phenotype of mutant mice deficient in several Ephs and ephrins B has been determined. Remarkably, thymic stroma in these animals exhibits important defects that appear early in ontogeny but little alterations in the proportions of distinct lymphoid cell populations. In the present manuscript, we summarize and extend these results discussing possible mechanisms governing phenotypical and functional thymocyte maturation in an absence of the critical T–TEC interactions, concluding that some signaling mediated by key molecules, such as MHCII, CD80, β5t, Aire, etc. could be sufficient to enable a proper maturation of thymocytes, independently of morphological alterations affecting thymic epithelium.

Natural bond orbital analysis of molecular interactions: Theoretical study of W(CO)5 complexes with E(PH3)2 and NHEMe ligands (E=C, Si, Ge, Sn, Pb)

International Nuclear Information System (INIS)

Nguyen Thi Ai Nhung; Huynh Thi Phuong Loan; Duong Tuan Quang; Pham Van Tat

2014-01-01

The complexes with ligands carbodiphosphorane-analogues (called tetrylones) [(CO) 5 W-{E(PH 3 ) 2 }] (W5-EP 2 ) and N-heterocyclic carbene-analogues (called tetrylenes) [(CO) 5 W-{NHE Me }] (W5-NHE Me ) when E=C-Pb have been studied using natural bond orbital (NBO) method. The NBO analysis provides a consistent picture of the chemical bonding is two entire families of transition metal complexes of tetrylone and tetrylene ligands in term of donor-acceptor interactions, showing the correlation of these interactions with Wiberg bond indies (WBI), natural partial charges, and the energetically highest lying occupied molecular orbitals for σ and π orbitals of free ligands E(PH 3 ) 2 and NHE Me . Analysis of the bonding situation reveals that in E(PH 3 ) 2 and NHE Me ligands, the energy level of the π orbital rises, whereas that of the σ orbital decreases as atom E becomes heavier. The complexes with head-on-bonded ligands have (CO) 5 W←E donation which comes from the σ-lone-pair orbital of E(PH 3 ) 2 and NHE Me where E=C for tetrylones and E=C, Si, Ge for tetrylenes, whereas the (CO) 5 W←E donation in the side-on bonded complexes when E becomes heavier arises from the π-lone-pair orbital of E(PH 3 ) 2 and NHE Me ligands which is the HOMO of the free ligands. This makes the heavier adducts of tetrylones and tetrylenes become stronger donors than the lighter systems. The NBO analysis suggests that the E(PH 3 ) 2 ligands are strong σ-donors and strong π-acceptors while the NHE Me ligands are strong σ-donors and weak π-acceptors. This is possible for tetrylones that have two lone-pair orbitals available for donation, whereas the tetrylenes have only one lone-pair orbital available for donation. (author)

Complex formation of EphB1/Nck/Caskin1 leads to tyrosine phosphorylation and structural changes of the Caskin1 SH3 domain

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Pesti Szabolcs

2012-11-01

Full Text Available Abstract Background Scaffold proteins have an important role in the regulation of signal propagation. These proteins do not possess any enzymatic activity but can contribute to the formation of multiprotein complexes. Although scaffold proteins are present in all cell types, the nervous system contains them in the largest amount. Caskin proteins are typically present in neuronal cells, particularly, in the synapses. However, the signaling mechanisms by which Caskin proteins are regulated are largely unknown. Results Here we demonstrate that EphB1 receptor tyrosine kinase can recruit Caskin1 through the adaptor protein Nck. Upon activation of the receptor kinase, the SH2 domain of Nck binds to one of its tyrosine residues, while Nck SH3 domains interact with the proline-rich domain of Caskin1. Complex formation of the receptor, adaptor and scaffold proteins results in the tyrosine phosphorylation of Caskin1 on its SH3 domain. The phosphorylation sites were identified by mass-spectrometry as tyrosines 296 and 336. To reveal the structural consequence of this phosphorylation, CD spectroscopy was performed. This measurement suggests that upon tyrosine phosphorylation the structure of the Caskin1 SH3 domain changes significantly. Conclusion Taken together, we propose that the scaffold protein Caskin1 can form a complex with the EphB1 tyrosine kinase via the Nck protein as a linker. Complex formation results in tyrosine phosphorylation of the Caskin1 SH3 domain. Although we were not able to identify any physiological partner of the SH3 domain so far, we could demonstrate that phosphorylation on conserved tyrosine residues results in marked changes in the structure of the SH3 domain.

Promoting health equity in European children: Design and methodology of the prospective EPHE (Epode for the Promotion of Health Equity) evaluation study

NARCIS (Netherlands)

Mantziki, K.; Vassilopoulos, A.; Radulian, G.; Borys, J.M.; Du Plessis, A.J.; Gregorio, M.J.; Graca, G.; de Henauw, S.; Handjiev, S.; Visscher, T.L.S.; Seidell, J.C.

2014-01-01

BACKGROUND: Reducing health inequalities is a top priority of the public health agendas in Europe. The EPHE project aims to analyse the added value of a community-based interventional programme based on EPODE methodology, adapted for the reduction of socio-economic inequalities in childhood obesity.

Epicondylopathia humeri (EPH) and peritendinitis humeroscapularis (PHS): evaluation of radiation therapy long-term results and literature review

International Nuclear Information System (INIS)

Seegenschmiedt, M.H.; Keilholz, L.

1998-01-01

Background: The effectiveness of radiotherapy (RT) for degenerative inflammatory disorders has been clinically documented in historical studies, but long-term follow-up and assessment with objective criteria are still not available. Patients and methods: From 1986 to 1991, 200 consecutive patients with symptomatic epicondylopathia humeri (EPH, n=104) and peritendinitis humeroscapularis (PHS, n=96) were referred to our clinic. All patients were refractory to conventional therapy prior to irradiation. One hundred fifty-six patients with 192 sites (due to bilateral symptoms) received a full treatment course and were available for long-term follow-up, i.e. 83 patients with 93 elbows and 73 patients with 89 shoulders. The treatment response was evaluated with regard to pain symptoms grouped into five categories (pain at strain, pain at night, persistent pain during daytime, pain at rest and morning stiffness) and four grades (none, mild, moderate and severe) and with regard to established orthopedic scores (Morrey score and Constant and Murley score). The analysis was performed before and 6 weeks after RT and at last follow-up. All joints received two RT series applied in three weekly fractions (EPH, 6x1 Gy (total 12 Gy); PHS, 6x0.5 Gy (total 6 Gy)). The second RT series started 6 weeks after the first RT series. The minimum follow-up was 1 year for both groups and the mean follow-up reached 4 years (range 1-8 years). Results: Fifty elbows (43 patients) and 44 shoulders (39 patients) achieved complete pain relief in all pain categories; 24 elbows and 28 shoulders substantially improved, i.e. had only minor symptoms. Thus, 74 elbows and 72 shoulders responded to RT. Nineteen elbows (17 patients) had surgery after RT due to persisting symptoms or subjective dissatisfaction; 17 shoulders (12 patients) were non-responders and five of those were operated on; seven elbows and one shoulder were completely free of pain after surgery. The mean Morrey score improved by 18 points

Building the pipeline: programs to introduce middle school, high school, medical, and veterinary students to careers in epidemiology and public health.

Science.gov (United States)

Cordell, Ralph L; Cordeira, Kelly L; Cohen, Laurence P; Bensyl, Diana M

2017-11-01

This report describes Centers for Disease Control and Prevention programs that expose students to epidemiology and public health sciences (EPHS). The Science Ambassador workshop targets middle and high school teachers and promotes teaching EPHS in the classroom. The National Science Olympiad Disease Detectives event is an extracurricular science competition for middle and high school students based on investigations of outbreaks and other public health problems. The Epidemiology Elective Program provides experiential learning activities for veterinary and medical students. As of 2016, 234 teachers from 37 states and territories and three other countries participated in SA workshops. Several are teaching units or entire courses in EPHS. The National Science Olympiad Disease Detectives event exposed approximately 15,000 middle and high school students to EPHS during the 2015-2016 school year. The Epidemiology Elective Program has exposed 1,795 veterinary and medical students to EPHS. Students can master fundamental concepts of EPHS as early as middle school and educators are finding ways to introduce this material into their classrooms. Programs to introduce veterinary and medical students to EPHS can help fill the gap in exposing older students to the field. Professional organizations can assist by making their members aware of these programs. Published by Elsevier Inc.

Solution structure of the receptor tyrosine kinase EphB2 SAM domain and identification of two distinct homotypic interaction sites.

OpenAIRE

Smalla, M.; Schmieder, P.; Kelly, M.; Ter Laak, A.; Krause, G.; Ball, L.; Wahl, M.; Bork, P.; Oschkinat, H.

1999-01-01

The sterile alpha motif (SAM) is a protein interaction domain of around 70 amino acids present predominantly in the N- and C-termini of more than 60 diverse proteins that participate in signal transduction and transcriptional repression. SAM domains have been shown to homo- and hetero-oligomerize and to mediate specific protein-protein interactions. A highly conserved subclass of SAM domains is present at the intracellular C-terminus of more than 40 Eph receptor tyrosine kinases that are invo...

The effect of conditional EFNB1 deletion in the T cell compartment on T cell development and function

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Jin Wei

2011-12-01

Full Text Available Abstract Background Eph kinases are the largest family of cell surface receptor tyrosine kinases. The ligands of Ephs, ephrins (EFNs, are also cell surface molecules. Ephs interact with EFNs transmitting signals in both directions, i.e., from Ephs to EFNs and from EFNs to Ephs. EFNB1 is known to be able to co-stimulate T cells in vitro and to modulate thymocyte development in a model of foetal thymus organ culture. To further understand the role of EFNB1 in T cell immunity, we generated T-cell-specific EFNB1 gene knockout mice to assess T cell development and function in these mice. Results The mice were of normal size and cellularity in the thymus and spleen and had normal T cell subpopulations in these organs. The bone marrow progenitors from KO mice and WT control mice repopulated host spleen T cell pool to similar extents. The activation and proliferation of KO T cells was comparable to that of control mice. Naïve KO CD4 cells showed an ability to differentiate into Th1, Th2, Th17 and Treg cells similar to control CD4 cells. Conclusions Our results suggest that the function of EFNB1 in the T cell compartment could be compensated by other members of the EFN family, and that such redundancy safeguards the pivotal roles of EFNB1 in T cell development and function.

The simultaneous expression of both ephrin B3 receptor and E-cadherin in Barrett`s adenocarcinoma is associated with favorable clinical staging

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Schauer Matthias C

2012-05-01

Full Text Available Abstract Background In intestinal epithelium, tyrosine kinase receptor Ephrin B3 (Eph B3 maintains the architecture of the crypt-villus axis by repulsive interaction with its ligand ephrin-B1. While loss of Eph B3 is linked to colorectal cancer initiation, overexpression of Eph B3 in cancer cell lines inhibits growth and induces functional changes with decreased mesenchymal and increased epithelial markers. In order to study this tumor suppressor activity of Eph B3 in esophageal adenocarcinoma we analyzed the simultaneous expression of Eph B3 and E-cadherin in both the healthy esophagus and in Barrett’s carcinoma. Methods Simultaneous expression of Eph B3 and E-cadherin was investigated in samples from 141 patients with Barrett’s carcinoma and from 20 healthy esophagi using immunhistology and quantitative PCR. Results from healthy squamous epithelium, Barrett’s metaplasia and staging-specific esophageal adenocarcinoma were correlated. Results A significantly reduced E-cadherin mRNA expression could be detected in adenocarcinoma compared to dysplasia. The immunhistological activity of E-cadherin and Eph B3 was reduced in adenocarcinoma compared to dysplasia or healthy esophageal mucosa. The intracellular E-cadherin distribution changed significantly from the cytoplasm to the membrane, when the Eph receptor was simultaneously expressed. Simultaneous expression of E-cadherin and Eph B3 showed a significant inverse correlation to tumor stage. Conclusions We present novel evidence of the tumor suppressor activity of Eph B3 in esophageal adenocarcinoma possibly due to the impact on redistribution of cellular E-cadherin to the membrane. Our results suggest that this effect might play a role in the dysplasia-adenocarcinoma sequence, the infiltrative growth pattern and the development of lymph node metastases.

Morphology of the villous chorion maldevelopment in early forms of EPH-gestosis combined with anemia of pregnancy

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N. M. Lagoda

2012-08-01

Full Text Available On the basis of a complex morphological study of human placenta the characteristic structural features of villous maldevelopment in a combination of edema of pregnant and anemia of pregnancy are defined by the type of dissociated cotyledon development with retardation of the placental barrier functional specialization. This pathology leads to compensatory reactions of the placenta in the form of the restructuring of fetal blood vessels, aimed only at the oncoming of fetal and maternal blood flow without increasing of the vasculosyncytial membranes area. These changes were accompanied by complicated delivery and fetus state disorder characteristic for chronic feto-placental insufficiency, 2-nd degree of severity. Received results are the basis for inclusion of pregnant women with early form of EPH-gestosis (edema of pregnant in combination with anemia into the risk group of fetoplacental insufficiency developing and complicated delivery.

A pilot study of JI-101, an inhibitor of VEGFR-2, PDGFR-β, and EphB4 receptors, in combination with everolimus and as a single agent in an ovarian cancer expansion cohort.

Science.gov (United States)

Werner, Theresa L; Wade, Mark L; Agarwal, Neeraj; Boucher, Kenneth; Patel, Jesal; Luebke, Aaron; Sharma, Sunil

2015-12-01

JI-101 is an oral multi-kinase inhibitor that targets vascular endothelial growth factor receptor type 2 (VEGFR-2), platelet derived growth factor receptor β (PDGFR-β), and ephrin type-B receptor 4 (EphB4). None of the currently approved angiogenesis inhibitors have been reported to inhibit EphB4, and therefore, JI-101 has a novel mechanism of action. We conducted a pilot trial to assess the pharmacokinetics (PK), tolerability, and efficacy of JI-101 in combination with everolimus in advanced cancers, and pharmacodynamics (PD), tolerability, and efficacy of JI-101 in ovarian cancer. This was the first clinical study assessing anti-tumor activity of JI-101 in a combinatorial regimen. In the PK cohort, four patients received single agent 10 mg everolimus on day 1, 10 mg everolimus and 200 mg JI-101 combination on day 8, and single agent 200 mg JI-101 on day 15. In the PD cohort, eleven patients received single agent JI-101 at 200 mg twice daily for 28 day treatment cycles. JI-101 was well tolerated as a single agent and in combination with everolimus. No serious adverse events were observed. Common adverse events were hypertension, nausea, and abdominal pain. JI-101 increased exposure of everolimus by approximately 22%, suggestive of drug-drug interaction. The majority of patients had stable disease at their first set of restaging scans (two months), although no patients demonstrated a response to the drug per RECIST criteria. The novel mechanism of action of JI-101 is promising in ovarian cancer treatment and further prospective studies of this agent may be pursued in a less refractory patient population or in combination with cytotoxic chemotherapy.

Construction and characterisation of a genetically engineered Escherichia coli strain for the epoxide hydrolase-catalysed kinetic resolution of epoxides

NARCIS (Netherlands)

Visser, H.; Oliveira Vil Filho, de M.; Liese, A.; Weijers, C.A.G.M.; Verdoes, J.C.

2003-01-01

The Rhodotorula glutinis epoxide hydrolase, Eph1, was produced in the heterologous host Escherichia coli BL21(DE3) in order to develop a highly effective epoxide hydrolysis system. A 138-fold increase in Eph1 activity was found in cell extracts of the recombinant E. coli when compared to cell

EphrinB1 expression is dysregulated and promotes oncogenic signaling in medulloblastoma.

Science.gov (United States)

McKinney, Nicole; Yuan, Liangping; Zhang, Hongying; Liu, Jingbo; Cho, Yoon-Jae; Rushing, Elisabeth; Schniederjan, Matthew; MacDonald, Tobey J

2015-01-01

Eph receptors and ephrin ligands are master regulators of oncogenic signaling required for proliferation, migration, and metastasis. Yet, Eph/ephrin expression and activity in medulloblastoma (MB), the most common malignant brain tumor of childhood, remains poorly defined. We hypothesized that Eph/ephrins are differentially expressed by sonic hedgehog (SHH) and non-SHH MB and that specific members contribute to the aggressive phenotype. Affymetrix gene expression profiling of 29 childhood MB, separated into SHH (N = 11) and non-SHH (N = 18), was performed followed by protein validation of selected Eph/ephrins in another 60 MB and two MB cell lines (DAOY, D556). Functional assays were performed using MB cells overexpressing or deleted for selected ephrins. We found EPHB4 and EFNA4 almost exclusively expressed by SHH MB, whereas EPHA2, EPHA8, EFNA1 and EFNA3 are predominantly expressed by non-SHH MB. The remaining family members, except EFNB1, are ubiquitously expressed by over 70-90 % MB, irrespective of subgroup. EFNB1 is the only member differentially expressed by 28 % of SHH and non-SHH MB. Corresponding protein expression for EphB/ephrinB1 and B2 was validated in MB. Only ephrinB2 was also detected in fetal cerebellum, indicating that EphB/ephrinB1 expression is MB-specific. EphrinB1 immunopositivity localizes to tumor cells within MB with the highest proliferative index. EphrinB1 overexpression promotes EphB activation, alters F-actin distribution and morphology, decreases adhesion, and significantly promotes proliferation. Either silencing or overexpression of ephrinB1 impairs migration. These results indicate that EphrinB1 is uniquely dysregulated in MB and promotes oncogenic responses in MB cells, implicating ephrinB1 as a potential target.

Inequities in energy-balance related behaviours and family environmental determinants in European children: baseline results of the prospective EPHE evaluation study.

Science.gov (United States)

Mantziki, Krystallia; Vassilopoulos, Achilleas; Radulian, Gabriella; Borys, Jean-Michel; Du Plessis, Hugues; Gregório, Maria João; Graça, Pedro; De Henauw, Stefaan; Handjiev, Svetoslav; Visscher, Tommy Ls; Seidell, Jacob C

2015-12-02

Tackling inequalities in overweight, obesity and related determinants has become a top priority for the European research and policy agendas. Although it has been established that such inequalities accumulate from early childhood onward, they have not been studied extensively in children. The current article discusses the results of an explorative analysis for the identification of inequalities in behaviours and their determinants between groups with high and low socio-economic status. This study is part of the Epode for the Promotion of Health Equity (EPHE) evaluation study, the overall aim of which is to assess the impact and sustainability of EPODE methodology to diminish inequalities in childhood obesity and overweight. Seven community-based programmes from different European countries (Belgium, Bulgaria, France, Greece, Portugal, Romania, The Netherlands) participate in the EPHE study. In each of the communities, children aged 6-8 years participated, resulting in a total sample of 1266 children and their families. A parental self-administrated questionnaire was disseminated in order to assess the socio-economic status of the household, selected energy balance-related behaviours (1. fruit and vegetable consumption; 2. soft drink/ fruit juices and water consumption; 3. screen time and 4. sleep duration) of the children and associated family environmental determinants. The Mann-Whitney U test and Pearson's chi-square test were used to test differences between the low and high education groups. The country-specific median was chosen as the cut-off point to determine the educational level, given the different average educational level in every country. Children with mothers of relatively high educational level consumed fruits and vegetables more frequently than their peers of low socio-economic status. The latter group of children had a higher intake of fruit juices and/or soft drinks and had higher screen time. Parental rules and home availability were

Abnormal expression of ephrin-A5 affects brain development of congenital hypothyroidism rats.

Science.gov (United States)

Suo, Guihai; Shen, Feifei; Sun, Baolan; Song, Honghua; Xu, Meiyu; Wu, Youjia

2018-05-14

EphA5 and its ligand ephrin-A5 interaction can trigger synaptogenesis during early hippocampus development. We have previously reported that abnormal EphA5 expression can result in synaptogenesis disorder in congenital hypothyroidism (CH) rats. To better understand its precise molecular mechanism, we further analyzed the characteristics of ephrin-A5 expression in the hippocampus of CH rats. Our study revealed that ephrin-A5 expression was downregulated by thyroid hormone deficiency in the developing hippocampus and hippocampal neurons in rats. Thyroxine treatment for hypothyroid hippocampus and triiodothyronine treatment for hypothyroid hippocampal neurons significantly improved ephrin-A5 expression but could not restore its expression to control levels. Hypothyroid hippocampal neurons in-vitro showed synaptogenesis disorder characterized by a reduction in the number and length of neurites. Furthermore, the synaptogenesis-associated molecular expressions of NMDAR-1 (NR1), PSD95 and CaMKII were all downregulated correspondingly. These results suggest that ephrin-A5 expression may be decreased in CH, and abnormal activation of ephrin-A5/EphA5 signaling affects synaptogenesis during brain development. Such findings provide an important basis for exploring the pathogenesis of CH genetically.

The Influence of pH of Extracting Water on the Composition of Seaweed Extracts and Their Beneficial Properties on Lepidium sativum.

Science.gov (United States)

Godlewska, Katarzyna; Michalak, Izabela; Tuhy, Łukasz; Chojnacka, Katarzyna

2017-01-01

Baltic seaweeds were used to obtain aqueous extracts (E) through changing initial pH of deionised water added to algal biomass (EpH3·H 2 O, EpH7·H 2 O, and EpH10·H 2 O) and through changing pH of the mixture of algae and deionised water (EpH3, EpH7, and EpH10). Algal extracts were characterized in terms of the concentration of polyphenols and micro- and macroelements. The highest concentration of polyphenols was determined in extract EpH3 and the lowest in extract EpH10·H 2 O. It was found that the obtained extracts had similar concentrations of elements (except EpH3). The phytotoxicity of algal extracts (0.5, 2.5, and 10%) was examined in the germination tests on Lepidium sativum . No phytotoxic effects were observed. It was found that they had beneficial effects on the cultivated plants (length and weight). The best biostimulant effect was observed in the groups treated with EpH3 (2.5%), EpH7 (2.5%), and EpH7 (10%). The dry weight of plants was similar in all the groups. Algal extract also improved the multielemental composition of plant. The greatest concentration of total chlorophyll in plants was obtained by using extract EpH10·H 2 O, 0.5%. These results proved that algal extracts have high potential to be applied in cultivation of plants.

The Influence of pH of Extracting Water on the Composition of Seaweed Extracts and Their Beneficial Properties on Lepidium sativum

Directory of Open Access Journals (Sweden)

Katarzyna Godlewska

2017-01-01

Full Text Available Baltic seaweeds were used to obtain aqueous extracts (E through changing initial pH of deionised water added to algal biomass (EpH3·H2O, EpH7·H2O, and EpH10·H2O and through changing pH of the mixture of algae and deionised water (EpH3, EpH7, and EpH10. Algal extracts were characterized in terms of the concentration of polyphenols and micro- and macroelements. The highest concentration of polyphenols was determined in extract EpH3 and the lowest in extract EpH10·H2O. It was found that the obtained extracts had similar concentrations of elements (except EpH3. The phytotoxicity of algal extracts (0.5, 2.5, and 10% was examined in the germination tests on Lepidium sativum. No phytotoxic effects were observed. It was found that they had beneficial effects on the cultivated plants (length and weight. The best biostimulant effect was observed in the groups treated with EpH3 (2.5%, EpH7 (2.5%, and EpH7 (10%. The dry weight of plants was similar in all the groups. Algal extract also improved the multielemental composition of plant. The greatest concentration of total chlorophyll in plants was obtained by using extract EpH10·H2O, 0.5%. These results proved that algal extracts have high potential to be applied in cultivation of plants.

Pharmacological targeting of the ephrin receptor kinase signalling by GLPG1790 in vitro and in vivo reverts oncophenotype, induces myogenic differentiation and radiosensitizes embryonal rhabdomyosarcoma cells

Directory of Open Access Journals (Sweden)

Francesca Megiorni

2017-10-01

Full Text Available Abstract Background EPH (erythropoietin-producing hepatocellular receptors are clinically relevant targets in several malignancies. This report describes the effects of GLPG1790, a new potent pan-EPH inhibitor, in human embryonal rhabdomyosarcoma (ERMS cell lines. Methods EPH-A2 and Ephrin-A1 mRNA expression was quantified by real-time PCR in 14 ERMS tumour samples and in normal skeletal muscle (NSM. GLPG1790 effects were tested in RD and TE671 cell lines, two in vitro models of ERMS, by performing flow cytometry analysis, Western blotting and immunofluorescence experiments. RNA interfering experiments were performed to assess the role of specific EPH receptors. Radiations were delivered using an x-6 MV photon linear accelerator. GLPG1790 (30 mg/kg in vivo activity alone or in combination with irradiation (2 Gy was determined in murine xenografts. Results Our study showed, for the first time, a significant upregulation of EPH-A2 receptor and Ephrin-A1 ligand in ERMS primary biopsies in comparison to NSM. GLPG1790 in vitro induced G1-growth arrest as demonstrated by Rb, Cyclin A and Cyclin B1 decrease, as well as by p21 and p27 increment. GLPG1790 reduced migratory capacity and clonogenic potential of ERMS cells, prevented rhabdosphere formation and downregulated CD133, CXCR4 and Nanog stem cell markers. Drug treatment committed ERMS cells towards skeletal muscle differentiation by inducing a myogenic-like phenotype and increasing MYOD1, Myogenin and MyHC levels. Furthermore, GLPG1790 significantly radiosensitized ERMS cells by impairing the DNA double-strand break repair pathway. Silencing of both EPH-A2 and EPH-B2, two receptors preferentially targeted by GLPG1790, closely matched the effects of the EPH pharmacological inhibition. GLPG1790 and radiation combined treatments reduced tumour mass by 83% in mouse TE671 xenografts. Conclusions Taken together, our data suggest that altered EPH signalling plays a key role in ERMS development and that

Is your electric process heater safe?

Energy Technology Data Exchange (ETDEWEB)

Tiras, C.S.

2000-04-01

Over the past 35 years, electric process heaters (EPHs) have been used to heat flowing fluids in different sectors of the energy industry: oil and gas exploration and production, refineries, petrochemical plants, pipeline compression facilities and power-generation plants. EPHs offer several advantages over fired heaters and shell-and-tube exchangers, which have been around for many years, including: smaller size, lighter weight, cleaner operation, lower capital costs, lower maintenance costs, no emissions or leakage, better control and improved safety. However, while many industrial standards have addressed safety concerns of fired heaters and shell-and-tube exchangers (API, TEMA, NFPA, OSHA and NEC), no standards address EPHs. The paper presents a list of questions that plant operators need to ask about the safety of their electric process heaters. The answers are also given.

Active noise control primer

CERN Document Server

Snyder, Scott D

2000-01-01

Active noise control - the reduction of noise by generating an acoustic signal that actively interferes with the noise - has become an active area of basic research and engineering applications. The aim of this book is to present all of the basic knowledge one needs for assessing how useful active noise control will be for a given problem and then to provide some guidance for designing, setting up, and tuning an active noise-control system. Written for students who have no prior knowledge of acoustics, signal processing, or noise control but who do have a reasonable grasp of basic physics and mathematics, the book is short and descriptive. It leaves for more advanced texts or research monographs all mathematical details and proofs concerning vibrations, signal processing and the like. The book can thus be used in independent study, in a classroom with laboratories, or in conjunction with a kit for experiment or demonstration. Topics covered include: basic acoustics; human perception and sound; sound intensity...

Active Control of Suspension Bridges

DEFF Research Database (Denmark)

Thoft-Christensen, Palle

In this paper some recent research on active control of very long suspension bridges, is presented. The presentation is based on research work at Aalborg University, Denmark. The active control system is based on movable flaps attached to the bridge girder. Wind load on bridges with or without...... flaps attached to the girder is briefly presented. A simple active control system is discussed. Results from wind tunnel experiments with a bridge section show that flaps can be used effectively to control bridge girder vibrations. Flutter conditions for suspension bridges with and without flaps...

TNYL peptide functional chitosan-g-stearate conjugate micelles for tumor specific targeting

Directory of Open Access Journals (Sweden)

Chen FY

2014-09-01

Full Text Available Feng-Ying Chen,1 Jing-Jing Yan,1 Han-Xi Yi,2 Fu-Qiang Hu,2 Yong-Zhong Du,2 Hong Yuan,2 Jian You,2 Meng-Dan Zhao1 1Women’s Hospital, School of Medicine, Zhejiang University, Hangzhou, People’s Republic of China; 2College of Pharmaceutical Science, Zhejiang University, Hangzhou, People’s Republic of China Abstract: Nowadays, a real challenge in cancer therapy is to design drug delivery systems that can achieve high concentrations of drugs at the target site for improved therapeutic effect with reduced side effects. In this research, we designed and synthesized a homing peptide-(TNYLFSPNGPIA, TNYL modified chitosan-g-stearate (CS polymer micelle (named T-CS for targeting delivery. The peptide displayed specific binding affinity to EphB4 which is a member of the Eph family of receptor tyrosine protein kinases. The amphiphilic polymer T-CS can gather into micelles by themselves in an aqueous environment with a low critical micelle concentration value (91.2 µg/L and nano-scaled size (82.1±2.8 nm. The drug encapsulation efficiency reached 86.43% after loading the hydrophobic drug doxorubicin (DOX. The cytotoxicity of T-CS/DOX against SKOV3 cells was enhanced by approximately 2.3-fold when compared with CS/DOX. The quantitative and qualitative analysis for cellular uptake indicated that TNYL modification can markedly increase cellular internalization in the EphB4-overexpressing SKOV3 cell line, especially with a short incubation time. It is interesting that relatively higher uptake of the T-CS/DOX micelles by SKOV3 cells (positive-EphB4 than A549 cells (negative-EphB4 was observed when the two cells were co-incubated. Furthermore, in vivo distribution experiment using a bilateral-tumor model showed that there was more fluorescence accumulation in the SKOV3 tumor than in the A549 tumor over the whole experiment. These results suggest that TNYL-modified CS micelles may be promising drug carriers as targeting therapy for the EphB4-overexpressing

Active vibration control by robust control techniques

International Nuclear Information System (INIS)

Lohar, F.A.

2001-01-01

This paper studies active vibration control of multi-degree-of-freedom system. The control techniques considered are LTR, H/sup 2/ and H/sup infinite/. The results show that LTR controls the vibration but its respective settling time is higher than that of the other techniques. The control performance of H/sup infinite/ control is similar to that of H/sup 2/ control in the case of it weighting functions. However, H/sup infinite/ control is superior to H/sup 2/ control with respect to robustness, steady state error and settling time. (author)

Active Control Of Structure-Borne Noise

Science.gov (United States)

Elliott, S. J.

1994-11-01

The successful practical application of active noise control requires an understanding of both its acoustic limitations and the limitations of the electrical control strategy used. This paper is concerned with the active control of sound in enclosures. First, a review is presented of the fundamental physical limitations of using loudspeakers to achieve either global or local control. Both approaches are seen to have a high frequency limit, due to either the acoustic modal overlap, or the spatial correlation function of the pressure field. These physical performance limits could, in principle, be achieved with either a feedback or a feedforward control strategy. These strategies are reviewed and the use of adaptive digital filters is discussed for both approaches. The application of adaptive feedforward control in the control of engine and road noise in cars is described. Finally, an indirect approach to the active control of sound is discussed, in which the vibration is suppressed in the structural paths connecting the source of vibration to the enclosure. Two specific examples of this strategy are described, using an active automotive engine mount and the incorporation of actuators into helicopter struts to control gear-meshing tones. In both cases good passive design can minimize the complexity of the active controller.

Equity of the essential public health service in rural china: evidence from a nationwide survey of hypertensive patients.

Science.gov (United States)

Zhou, Donghua; Feng, Zhanchun; He, Shasha; Sun, Xi; Ma, Caihui; Lv, Benyan; Zou, Xiong

2013-07-01

To explore healthcare disparities in rural China two years after the implementation of the Essential Public Health Service (EPHS) reform in 2009. A cross-sectional study was conducted by surveying 930 hypertension patients (HPs) from different regions in rural China in 2011. The percentages of patients using recommended four or more follow-up visits in a year were calculated by patient socio-demographic characteristics and statistically examined using chi-square and logistic regression to uncover disparities and correlated factors in EPHS use. The rates were not significantly different by age, gender, education, insurance status or income, but significantly different by region and hypertension history (p<0.01). Higher rates were also observed on patients who sought actively follow-up service at clinics, making appointment for the next follow-up with doctors, awareness of the need of follow-up, more satisfied with the follow-up services, and better medication adherence (p<0.01). There were no disparities observed among HPs in the use of follow-up services, suggesting that the reform has to some extent achieved its goal in ensuring equal access to EPHS. In this regard, regional implementation of the national policies and improvement of EPHS management at local level should be further improved.

Transmission of Turnip yellows virus by Myzus persicae Is Reduced by Feeding Aphids on Double-Stranded RNA Targeting the Ephrin Receptor Protein.

Science.gov (United States)

Mulot, Michaël; Monsion, Baptiste; Boissinot, Sylvaine; Rastegar, Maryam; Meyer, Sophie; Bochet, Nicole; Brault, Véronique

2018-01-01

Aphid-transmitted plant viruses are a threat for major crops causing massive economic loss worldwide. Members in the Luteoviridae family are transmitted by aphids in a circulative and non-replicative mode. Virions are acquired by aphids when ingesting sap from infected plants and are transported through the gut and the accessory salivary gland (ASG) cells by a transcytosis mechanism relying on virus-specific receptors largely unknown. Once released into the salivary canal, virions are inoculated to plants, together with saliva, during a subsequent feeding. In this paper, we bring in vivo evidence that the membrane-bound Ephrin receptor (Eph) is a novel aphid protein involved in the transmission of the Turnip yellows virus (TuYV, Polerovirus genus, Luteoviridae family) by Myzus persicae . The minor capsid protein of TuYV, essential for aphid transmission, was able to bind the external domain of Eph in yeast. Feeding M. persicae on in planta - or in vitro -synthesized dsRNA targeting Eph -mRNA (dsRNA Eph ) did not affect aphid feeding behavior but reduced accumulation of TuYV genomes in the aphid's body. Consequently, TuYV transmission efficiency by the dsRNA Eph -treated aphids was reproducibly inhibited and we brought evidence that Eph is likely involved in intestinal uptake of the virion. The inhibition of virus uptake after dsRNA Eph acquisition was also observed for two other poleroviruses transmitted by M. persicae , suggesting a broader role of Eph in polerovirus transmission. Finally, dsRNA Eph acquisition by aphids did not affect nymph production. These results pave the way toward an ecologically safe alternative of insecticide treatments that are used to lower aphid populations and reduce polerovirus damages.

Inhibition of tumor vasculogenic mimicry and prolongation of host survival in highly aggressive gallbladder cancers by norcantharidin via blocking the ephrin type a receptor 2/focal adhesion kinase/paxillin signaling pathway.

Directory of Open Access Journals (Sweden)

Hui Wang

Full Text Available Vasculogenic mimicry (VM is a newly-defined tumor microcirculation pattern in highly aggressive malignant tumors. We recently reported tumor growth and VM formation of gallbladder cancers through the contribution of the ephrin type a receptor 2 (EphA2/focal adhesion kinase (FAK/Paxillin signaling pathways. In this study, we further investigated the anti-VM activity of norcantharidin (NCTD as a VM inhibitor for gallbladder cancers and the underlying mechanisms. In vivo and in vitro experiments to determine the effects of NCTD on tumor growth, host survival, VM formation of GBC-SD nude mouse xenografts, and vasculogenic-like networks, malignant phenotypes i.e., proliferation, apoptosis, invasion and migration of GBC-SD cells. Expression of VM signaling-related markers EphA2, FAK and Paxillin in vivo and in vitro were examined by immunofluorescence, western blotting and real-time polymerase chain reaction (RT-PCR, respectively. The results showed that after treatment with NCTD, GBC-SD cells were unable to form VM structures when injecting into nude mouse, growth of the xenograft was inhibited and these observations were confirmed by facts that VM formation by three-dimensional (3-D matrix, proliferation, apoptosis, invasion, migration of GBC-SD cells were affected; and survival time of the xenograft mice was prolonged. Furthermore, expression of EphA2, FAK and Paxillin proteins/mRNAs of the xenografts was downregulated. Thus, we concluded that NCTD has potential anti-VM activity against human gallbladder cancers; one of the underlying mechanisms may be via blocking the EphA2/FAK/Paxillin signaling pathway.

p130Cas scaffolds the signalosome to direct adaptor-effector cross talk during Kaposi's sarcoma-associated herpesvirus trafficking in human microvascular dermal endothelial cells.

Science.gov (United States)

Bandyopadhyay, Chirosree; Veettil, Mohanan Valiya; Dutta, Sujoy; Chandran, Bala

2014-12-01

Kaposi's sarcoma-associated herpesvirus (KSHV) interacts with cell surface receptors, such as heparan sulfate, integrins (α3β1, αVβ3, and αVβ5), and EphrinA2 (EphA2), and activates focal adhesion kinase (FAK), Src, phosphoinositol 3-kinase (PI3-K), c-Cbl, and RhoA GTPase signal molecules early during lipid raft (LR)-dependent productive macropinocytic entry into human dermal microvascular endothelial cells. Our recent studies have identified CIB1 as a signal amplifier facilitating EphA2 phosphorylation and subsequent cytoskeletal cross talk during KSHV macropinocytosis. Although CIB1 lacks an enzymatic activity and traditional adaptor domain or known interacting sequence, it associated with the KSHV entry signal complex and the CIB1-KSHV association was sustained over 30 min postinfection. To identify factors scaffolding the EphA2-CIB1 signal axis, the role of major cellular scaffold protein p130Cas (Crk-associated substrate of Src) was investigated. Inhibitor and small interfering RNA (siRNA) studies demonstrated that KSHV induced p130Cas in an EphA2-, CIB1-, and Src-dependent manner. p130Cas and Crk were associated with KSHV, LRs, EphA2, and CIB1 early during infection. Live-cell microscopy and biochemical studies demonstrated that p130Cas knockdown did not affect KSHV entry but significantly reduced productive nuclear trafficking of viral DNA and routed KSHV to lysosomal degradation. p130Cas aided in scaffolding adaptor Crk to downstream guanine nucleotide exchange factor phospho-C3G possibly to coordinate GTPase signaling during KSHV trafficking. Collectively, these studies demonstrate that p130Cas acts as a bridging molecule between the KSHV-induced entry signal complex and the downstream trafficking signalosome in endothelial cells and suggest that simultaneous targeting of KSHV entry receptors with p130Cas would be an attractive potential avenue for therapeutic intervention in KSHV infection. Eukaryotic cell adaptor molecules, without any intrinsic

Correlation of contrast-enhanced ultrasound parameters with oncogene expression and cell proliferation activity in breast cancer

Institute of Scientific and Technical Information of China (English)

Ce Zhang

2017-01-01

Objective: To study the correlation of contrast-enhanced ultrasound parameters with oncogene expression and cell proliferation activity in breast cancer. Methods: Breast cancer lesions and benign breast lesions surgically removed in Zigong Third People's Hospital between May 2014 and February 2017 were selected, contrast-enhanced ultrasound was done before operation to draw the time-intensity curve and calculate the area under the curve (AUC), and the expression of proliferation molecules and tumor suppressor genes were detected after operation. Results:The contrast-enhanced ultrasound parameter AUC of the breast cancer lesion was greatly higher than that of the benign breast lesion; ECT2, ZKSCAN3, USP39 and EphA2 mRNA expression in breast cancer lesions were obviously higher than those in benign breast lesions whereas HPK1, TCEAL17, CCN5, ATG2B and ATG4D mRNA expression were greatly lower than those in benign breast lesions; ECT2, ZKSCAN3, USP39 and EphA2 mRNA expression in breast cancer lesions with high AUC were greatly higher than those in breast cancer lesions with low AUC whereas HPK1, TCEAL17, CCN5, ATG2B and ATG4D mRNA expression were greatly lower than those in breast cancer lesions with low AUC. Conclusion: The contrast-enhanced ultrasound parameter AUC of breast cancer lesion significantly increases and is closely related to the higher expression of pro-proliferation molecules and the lower expression of tumor suppressor genes.

Active control versus recursive backstepping control of a chaotic ...

African Journals Online (AJOL)

In this paper active controllers and recursive backstepping controllers are designed for a third order chaotic system. The performances of these controllers in the control of the dynamics of the chaotic system are investigated numerically and are found to be effective. Comparison of their transient performances show that the ...

Optical control of antibacterial activity

Science.gov (United States)

Velema, Willem A.; van der Berg, Jan Pieter; Hansen, Mickel J.; Szymanski, Wiktor; Driessen, Arnold J. M.; Feringa, Ben L.

2013-11-01

Bacterial resistance is a major problem in the modern world, stemming in part from the build-up of antibiotics in the environment. Novel molecular approaches that enable an externally triggered increase in antibiotic activity with high spatiotemporal resolution and auto-inactivation are highly desirable. Here we report a responsive, broad-spectrum, antibacterial agent that can be temporally activated with light, whereupon it auto-inactivates on the scale of hours. The use of such a ‘smart’ antibiotic might prevent the build-up of active antimicrobial material in the environment. Reversible optical control over active drug concentration enables us to obtain pharmacodynamic information. Precisely localized control of activity is achieved, allowing the growth of bacteria to be confined to defined patterns, which has potential for the development of treatments that avoid interference with the endogenous microbial population in other parts of the organism.

Simulation of disturbance rejection control of half-car active suspension system using active disturbance rejection control with decoupling transformation

Science.gov (United States)

Hasbullah, Faried; Faris, Waleed F.

2017-12-01

In recent years, Active Disturbance Rejection Control (ADRC) has become a popular control alternative due to its easy applicability and robustness to varying processes. In this article, ADRC with input decoupling transformation (ADRC-IDT) is proposed to improve ride comfort of a vehicle with an active suspension system using half-car model. The ride performance of the ADRC-IDT is evaluated and compared with decentralized ADRC control as well as the passive system. Simulation results show that both ADRC and ADRC-IDT manage to appreciably reduce body accelerations and able to cope well with varying conditions typically encountered in an active suspension system. Also, it is sufficient to control only the body motions with both active controllers to improve ride comfort while maintaining good road holding and small suspension working space.

Active-Reactive Additional Damping Control of a Doubly-Fed Induction Generator Based on Active Disturbance Rejection Control

Directory of Open Access Journals (Sweden)

Yanfeng Ma

2018-05-01

Full Text Available Large-scale wind power interfacing to the power grid has an impact on the stability of the power system. However, with an additional damping controller of the wind generator, new ways for improving system damping and suppressing the low frequency oscillation (LFO of power systems can be put forward. In this paper, an active-reactive power additional damping controller based on active disturbance rejection control (ADRC is proposed. In order to improve the precision of the controller, the theory of data driven control is adopted, using the numerical algorithms for subspace state space system identification (N4SID to obtain the two order model of the ADRC controlled object. Based on the identification model, the ADRC additional damping controller is designed. Taking a 2-area 4-machine system containing the doubly fed induction generator (DFIG wind farm as an example, it is verified that the active-reactive additional damping controller designed in this paper performs well in suppressing negative-damping LFO and forced power oscillation. When the operation state of the power system changes, it can still restrain the LFO effectively, showing stronger robustness and better effectiveness compared to the traditional proportional–integral–derivative (PID additional damping controller.

Active fault diagnosis by controller modification

DEFF Research Database (Denmark)

Stoustrup, Jakob; Niemann, Hans Henrik

2010-01-01

Two active fault diagnosis methods for additive or parametric faults are proposed. Both methods are based on controller reconfiguration rather than on requiring an exogenous excitation signal, as it is otherwise common in active fault diagnosis. For the first method, it is assumed that the system...... considered is controlled by an observer-based controller. The method is then based on a number of alternate observers, each designed to be sensitive to one or more additive faults. Periodically, the observer part of the controller is changed into the sequence of fault sensitive observers. This is done...... in a way that guarantees the continuity of transition and global stability using a recent result on observer parameterization. An illustrative example inspired by a field study of a drag racing vehicle is given. For the second method, an active fault diagnosis method for parametric faults is proposed...

An activated form of ADAM10 is tumor selective and regulates cancer stem-like cells and tumor growth

Science.gov (United States)

Saha, Nayanendu; Eissman, Moritz F.; Xu, Kai; Llerena, Carmen; Kusebauch, Ulrike; Ding, Bi-Sen; Cao, Zhongwei; Rafii, Shahin; Ernst, Matthias; Scott, Andrew M.; Nikolov, Dimitar B.; Lackmann, Martin

2016-01-01

The transmembrane metalloprotease ADAM10 sheds a range of cell surface proteins, including ligands and receptors of the Notch, Eph, and erbB families, thereby activating signaling pathways critical for tumor initiation and maintenance. ADAM10 is thus a promising therapeutic target. Although widely expressed, its activity is normally tightly regulated. We now report prevalence of an active form of ADAM10 in tumors compared with normal tissues, in mouse models and humans, identified by our conformation-specific antibody mAb 8C7. Structure/function experiments indicate mAb 8C7 binds an active conformation dependent on disulfide isomerization and oxidative conditions, common in tumors. Moreover, this active ADAM10 form marks cancer stem-like cells with active Notch signaling, known to mediate chemoresistance. Importantly, specific targeting of active ADAM10 with 8C7 inhibits Notch activity and tumor growth in mouse models, particularly regrowth after chemotherapy. Our results indicate targeted inhibition of active ADAM10 as a potential therapy for ADAM10-dependent tumor development and drug resistance. PMID:27503072

Control and synchronisation of a novel seven-dimensional hyperchaotic system with active control

Science.gov (United States)

Varan, Metin; Akgul, Akif

2018-04-01

In this work, active control method is proposed for controlling and synchronising seven-dimensional (7D) hyperchaotic systems. The seven-dimensional hyperchaotic system is considered for the implementation. Seven-dimensional hyperchaotic system is also investigated via time series, phase portraits and bifurcation diagrams. For understanding the impact of active controllers on global asymptotic stability of synchronisation and control errors, the Lyapunov function is used. Numerical analysis is done to reveal the effectiveness of applied active control method and the results are discussed.

Prevalence of active trachoma two years after control activities ...

African Journals Online (AJOL)

The prevalence of TF/TI showed significant reduction (p-value <0.001) in all five districts and overall in the two regions. Conclusion: Trachoma control activities over a two-year period in two regions in Ghana had led to significant reduction in the prevalence of active disease. Integrated surveillance and active monitoring will ...

The effects of physical activity on functional MRI activation associated with cognitive control in children: a randomized controlled intervention

Directory of Open Access Journals (Sweden)

Laura eChaddock-Heyman

2013-03-01

Full Text Available This study used functional magnetic resonance imaging (fMRI to examine the influence of a 9-month physical activity program on task-evoked brain activation during childhood. The results demonstrated that 8- to 9-year-old children who participated in 60+ minutes of physical activity, 5 days per week, for 9 months, showed decreases in fMRI brain activation in the right anterior prefrontal cortex coupled with within-group improvements in performance on a task of attentional and interference control. Children assigned to a wait list control group did not show changes in brain function. Furthermore, at post-test, children in the physical activity group showed similar anterior frontal brain patterns and incongruent accuracy rates to a group of college-aged young adults. Children in the wait list control group still differed from the young adults in terms of anterior prefrontal activation and performance at post-test. There were no significant changes in fMRI activation in the anterior cingulate cortex for either group. These results suggest that physical activity during childhood may enhance specific elements of prefrontal cortex function involved in cognitive control.

Synchronization of Rikitake chaotic attractor using active control

International Nuclear Information System (INIS)

Vincent, U.E.

2005-01-01

Using synchronization technique based on control theory, we design an active controller which enables the synchronization of two identical Rikitake two-disc dynamo systems. Numerical simulations are used to show the robustness of the active control scheme in synchronizing coupled Rikitake dynamical systems. On the sequential application of the active control, transitions from temporary phase locking (TPL) state to complete synchronization state were found

Semi-active control of helicopter vibration using controllable stiffness and damping devices

Science.gov (United States)

Anusonti-Inthra, Phuriwat

Semi-active concepts for helicopter vibration reduction are developed and evaluated in this dissertation. Semi-active devices, controllable stiffness devices or controllable orifice dampers, are introduced; (i) in the blade root region (rotor-based concept) and (ii) between the rotor and the fuselage as semi-active isolators (in the non-rotating frame). Corresponding semi-active controllers for helicopter vibration reduction are also developed. The effectiveness of the rotor-based semi-active vibration reduction concept (using stiffness and damping variation) is demonstrated for a 4-bladed hingeless rotor helicopter in moderate- to high-speed forward flight. A sensitivity study shows that the stiffness variation of root element can reduce hub vibrations when proper amplitude and phase are used. Furthermore, the optimal semi-active control scheme can determine the combination of stiffness variations that produce significant vibration reduction in all components of vibratory hub loads simultaneously. It is demonstrated that desired cyclic variations in properties of the blade root region can be practically achieved using discrete controllable stiffness devices and controllable dampers, especially in the flap and lag directions. These discrete controllable devices can produce 35--50% reduction in a composite vibration index representing all components of vibratory hub loads. No detrimental increases are observed in the lower harmonics of blade loads and blade response (which contribute to the dynamic stresses) and controllable device internal loads, when the optimal stiffness and damping variations are introduced. The effectiveness of optimal stiffness and damping variations in reducing hub vibration is retained over a range of cruise speeds and for variations in fundamental rotor properties. The effectiveness of the semi-active isolator is demonstrated for a simplified single degree of freedom system representing the semi-active isolation system. The rotor

Control System Design of Shunt Active Power Filter Based on Active Disturbance Rejection and Repetitive Control Techniques

Directory of Open Access Journals (Sweden)

Le Ge

2014-01-01

Full Text Available To rely on joint active disturbance rejection control (ADRC and repetitive control (RC, in this paper, a compound control law for active power filter (APF current control system is proposed. According to the theory of ADRC, the uncertainties in the model and from the circumstance outside are considered as the unknown disturbance to the system. The extended state observer can evaluate the unknown disturbance. Next, RC is introduced into current loop to improve the steady characteristics. The ADRC is used to get a good dynamic performance, and RC is used to get a good static performance. A good simulation result is got through choosing and changing the parameters, and the feasibility, adaptability, and robustness of the control are testified by this result.

Manually controlled neutron-activation system

International Nuclear Information System (INIS)

Johns, R.A.; Carothers, G.A.

1982-01-01

A manually controlled neutron activation system, the Manual Reactor Activation System, was designed and built and has been operating at one of the Savannah River Plant's production reactors. With this system, samples can be irradiated for up to 24 hours and pneumatically transferred to a shielded repository for decay until their activity is low enough for them to be handled at a radiobench. The Manual Reactor Activation System was built to provide neutron activation of solid waste forms for the Alternative Waste Forms Leach Testing Program. Neutron activation of the bulk sample prior to leaching permits sensitive multielement radiometric analyses of the leachates

Robust Active Damping Control of LCL Filtered Grid Connected Converter Based Active Disturbance Rejection Control

DEFF Research Database (Denmark)

Abdeldjabar, Benrabah; Xu, Dianguo; Wang, Xiongfei

2016-01-01

This paper deals with the problem of LCL filter resonance in grid connected inverter control. The system equations are reformulated to allow the application of the active disturbance rejection control (ADRC). The resonance, assumed unknown, is treated as a disturbance, then estimated and mitigated...

Use of On-Site GC/MS Analysis to Distinguish Between Vapor Intrusion and Indoor Sources of VOCs

Science.gov (United States)

2013-11-01

Petroleum Hydrocarbons (ETPH), MA-EPH, MA- VPH . Microbiology Parameters: Total Coliform – MF mEndo (SM9222B), Total Coliform – MTF (SM9221B), E. Coli...Parameters: PCBs, PCBs in Oil, Organochlorine Pesticides, Technical Chlordane, Toxaphene, CT-Extractable Petroleum Hydrocarbons (ETPH), MA-EPH, MA- VPH ...Organic Parameters: 608, 624, 625, 8081A, 8082, 8330, 8151A, 8260B, 8270C, 3510C, 3630C, 5030B, ME- DRO, ME-GRO, MA-EPH, MA- VPH .) Solid Waste/Soil

THE CONTROL AND EVALUATION OF PROMOTIONAL ACTIVITIES

Directory of Open Access Journals (Sweden)

Felicia Sabou

2012-01-01

Full Text Available The paper focused on importance and benefits of control and evaluation of marketing activities. The control of efficiency review the assessment of the resources for marketing activity, checking also the efficiency of the human resources, advertising, promotion activities and distribution activities. In the analyse of human resources the most important ratio are: the average of costumers visits on a day, the number of custom order received from 100 visits, the number of new customers from a period, the number of lost customers from a period, the marketing human expenditures from all the sales.The strategic control is made to check if the objectives and the company strategy are adapted to the marketing environment.

Active Vibration Control of Hydrodynamic Journal Bearings

Science.gov (United States)

Tůma, J.; Šimek, J.; Škuta, J.; Los, J.; Zavadil, J.

Rotor instability is one of the most serious problems of high-speed rotors supported by sliding bearings. With constantly increasing parameters, new machines problems with rotor instability are encountered more and more often. Even though there are many solutions based on passive improvement of the bearing geometry to enlarge the operational speed range of the journal bearing, the paper deals with a working prototype of a system for the active vibration control of journal bearings with the use of piezoactuators. The actively controlled journal bearing consists of a movable bushing, which is actuated by two piezoactuators. It is assumed that the journal vibration is measured by a pair of proximity probes. Force produced by piezoactuators and acting at the bushing is controlled according to error signals derived from the proximity probe output signals. The active vibration control was tested with the use of a test rig, which consists of a rotor supported by two controllable journal bearings and driven by an inductive motor up to 23,000 rpm. As it was proved by experiments the active vibration control extends considerably the range of the rotor operational speed.

Active Noise Control for Dishwasher noise

Science.gov (United States)

Lee, Nokhaeng; Park, Youngjin

2016-09-01

The dishwasher is a useful home appliance and continually used for automatically washing dishes. It's commonly placed in the kitchen with built-in style for practicality and better use of space. In this environment, people are easily exposed to dishwasher noise, so it is an important issue for the consumers, especially for the people living in open and narrow space. Recently, the sound power levels of the noise are about 40 - 50 dBA. It could be achieved by removal of noise sources and passive means of insulating acoustical path. For more reduction, such a quiet mode with the lower speed of cycle has been introduced, but this deteriorates the washing capacity. Under this background, we propose active noise control for dishwasher noise. It is observed that the noise is propagating mainly from the lower part of the front side. Control speakers are placed in the part for the collocation. Observation part of estimating sound field distribution and control part of generating the anti-noise are designed for active noise control. Simulation result shows proposed active noise control scheme could have a potential application for dishwasher noise reduction.

Simulation model of an active stall wind turbine controller

Energy Technology Data Exchange (ETDEWEB)

Jauch, C.; Hansen, A.D.; Soerensen, P. [Risoe National Lab., Wind Energy Dept., Rosilde (Denmark); Blaabjerg, F. [Aalborg Univ., Inst. of Energy Technology (Denmark)

2004-07-01

This paper describes an active stall wind turbine controller. The objective is to develop a general model of an active stall controller in order to simulate the operation of grid connected active stall wind turbines. The active stall turbine concept and its control strategies are presented and evaluated on the basis of simulations. The presented controller is described for continuous operation under all wind speeds from start-up wind speed to shut doven wind speed. Due to its parametric implementation it is general i.e. it can represent different active stall wind turbine controllers and can be implemented in different simulation tools. (au)

Use of Compound-Specific Stable Isotope Analysis to Distinguish Between Vapor Intrusion and Indoor Sources of VOCs

Science.gov (United States)

2013-11-01

Chlorinated Hydrocarbons, Volatile Organics, TPH (HEM/SGT), CT- Extractable Petroleum Hydrocarbons (ETPH), MA-EPH, MA- VPH . Microbiology Parameters: Total...Toxaphene, CT-Extractable Petroleum Hydrocarbons (ETPH), MA-EPH, MA- VPH , Dicamba, 2,4-D, 2,4,5-T, 2,4,5-TP(Silvex), Dalapon, Volatile Organics (SW 8260...3510C, 3630C, 5030B, ME- DRO, ME-GRO, MA-EPH, MA- VPH .) Solid Waste/Soil (Inorganic Parameters: 9010B, 9012A, 9014A, 9030B, 9040B, 9045C, 6010B

Actively Controlling the Topological Transition of Dispersion Based on Electrically Controllable Metamaterials

Directory of Open Access Journals (Sweden)

Zhiwei Guo

2018-04-01

Full Text Available Topological transition of the iso-frequency contour (IFC from a closed ellipsoid to an open hyperboloid provides unique capabilities for controlling the propagation of light. However, the ability to actively tune these effects remains elusive, and the related experimental observations are highly desirable. Here, a tunable electric IFC in a periodic structure composed of graphene/dielectric multilayers is investigated by tuning the chemical potential of the graphene layer. Specially, we present the actively controlled transportation in two kinds of anisotropic zero-index media containing perfect electric conductor/perfect magnetic conductor impurities. Finally, by adding variable capacitance diodes into a two-dimensional transmission-line system, we present an experimental demonstration of the actively controlled magnetic topological transition of dispersion based on electrically controllable metamaterials. With the increase in voltage, we measure the different emission patterns from a point source inside the structure and observe the phase-transition process of IFCs. The realization of an actively tuned topological transition will open up a new avenue in the dynamical control of metamaterials.

Adaptive Piezoelectric Absorber for Active Vibration Control

Directory of Open Access Journals (Sweden)

Sven Herold

2016-02-01

Full Text Available Passive vibration control solutions are often limited to working reliably at one design point. Especially applied to lightweight structures, which tend to have unwanted vibration, active vibration control approaches can outperform passive solutions. To generate dynamic forces in a narrow frequency band, passive single-degree-of-freedom oscillators are frequently used as vibration absorbers and neutralizers. In order to respond to changes in system properties and/or the frequency of excitation forces, in this work, adaptive vibration compensation by a tunable piezoelectric vibration absorber is investigated. A special design containing piezoelectric stack actuators is used to cover a large tuning range for the natural frequency of the adaptive vibration absorber, while also the utilization as an active dynamic inertial mass actuator for active control concepts is possible, which can help to implement a broadband vibration control system. An analytical model is set up to derive general design rules for the system. An absorber prototype is set up and validated experimentally for both use cases of an adaptive vibration absorber and inertial mass actuator. Finally, the adaptive vibration control system is installed and tested with a basic truss structure in the laboratory, using both the possibility to adjust the properties of the absorber and active control.

Control of Sound Transmission with Active-Passive Tiles

OpenAIRE

Goldstein, Andre L.

2006-01-01

Nowadays, numerous applications of active sound transmission control require lightweight partitions with high transmission loss over a broad frequency range and simple control strategies. In this work an active-passive sound transmission control approach is investigated that potentially addresses these requirements. The approach involves the use of lightweight stiff panels, or tiles, attached to a radiating base structure through active-passive soft mounts and covering the structure surface. ...

Effect of alkaline cleaning and activation on aluminum alloy 7075-T6

International Nuclear Information System (INIS)

Joshi, Simon; Fahrenholtz, William G.; O'Keefe, Matthew J.

2011-01-01

The effect of alkaline cleaning and activation on the composition and thickness of the oxide layer on aluminum alloy 7075-T6 was studied. E-pH diagrams were developed to predict the effect of alkaline cleaning and activation solutions on the stability of the oxide surface layers. The thickness of the native oxide layer was determined to be ∼30 nm by Auger electron spectroscopy depth profiling analysis. The outer ∼20 nm was rich in magnesium while the remaining ∼10 nm was rich in aluminum. Cleaning in a 9.1 pH alkaline solution was found to remove the magnesium-rich layer and leave behind an aluminum-rich oxide layer ∼10 nm thick. Activation in alkaline solutions of NaOH (pH > 12.9) or Na 2 CO 3 (pH > 11.5) produced an oxide that was ∼20 to 60 nm thick and rich in magnesium. Alkaline cleaning and activation altered the oxide composition and thickness making it possible for deposition of thicker cerium-based conversion coatings (∼100 to 250 nm) compared to only alkaline cleaning (∼30 nm), with application of one spray cycle of deposition solution.

Effect of alkaline cleaning and activation on aluminum alloy 7075-T6

Energy Technology Data Exchange (ETDEWEB)

Joshi, Simon, E-mail: sjwt5@mst.edu [Department of Materials Science and Engineering, Missouri University of Science and Technology, Rolla, MO 65409 (United States); Fahrenholtz, William G.; O' Keefe, Matthew J. [Department of Materials Science and Engineering, Missouri University of Science and Technology, Rolla, MO 65409 (United States)

2011-01-01

The effect of alkaline cleaning and activation on the composition and thickness of the oxide layer on aluminum alloy 7075-T6 was studied. E-pH diagrams were developed to predict the effect of alkaline cleaning and activation solutions on the stability of the oxide surface layers. The thickness of the native oxide layer was determined to be {approx}30 nm by Auger electron spectroscopy depth profiling analysis. The outer {approx}20 nm was rich in magnesium while the remaining {approx}10 nm was rich in aluminum. Cleaning in a 9.1 pH alkaline solution was found to remove the magnesium-rich layer and leave behind an aluminum-rich oxide layer {approx}10 nm thick. Activation in alkaline solutions of NaOH (pH > 12.9) or Na{sub 2}CO{sub 3} (pH > 11.5) produced an oxide that was {approx}20 to 60 nm thick and rich in magnesium. Alkaline cleaning and activation altered the oxide composition and thickness making it possible for deposition of thicker cerium-based conversion coatings ({approx}100 to 250 nm) compared to only alkaline cleaning ({approx}30 nm), with application of one spray cycle of deposition solution.

Control of nucleus accumbens activity with neurofeedback.

Science.gov (United States)

Greer, Stephanie M; Trujillo, Andrew J; Glover, Gary H; Knutson, Brian

2014-08-01

The nucleus accumbens (NAcc) plays critical roles in healthy motivation and learning, as well as in psychiatric disorders (including schizophrenia and attention deficit hyperactivity disorder). Thus, techniques that confer control of NAcc activity might inspire new therapeutic interventions. By providing second-to-second temporal resolution of activity in small subcortical regions, functional magnetic resonance imaging (fMRI) can resolve online changes in NAcc activity, which can then be presented as "neurofeedback." In an fMRI-based neurofeedback experiment designed to elicit NAcc activity, we found that subjects could increase their own NAcc activity, and that display of neurofeedback significantly enhanced their ability to do so. Subjects were not as capable of decreasing their NAcc activity, however, and enhanced control did not persist after subsequent removal of neurofeedback. Further analyses suggested that individuals who recruited positive aroused affect were better able to increase NAcc activity in response to neurofeedback, and that NAcc neurofeedback also elicited functionally correlated activity in the medial prefrontal cortex. Together, these findings suggest that humans can modulate their own NAcc activity and that fMRI-based neurofeedback may augment their efforts. The observed association between positive arousal and effective NAcc control further supports an anticipatory affect account of NAcc function. Copyright © 2014 Elsevier Inc. All rights reserved.

Active disturbance rejection controller for chemical reactor

International Nuclear Information System (INIS)

Both, Roxana; Dulf, Eva H.; Muresan, Cristina I.

2015-01-01

In the petrochemical industry, the synthesis of 2 ethyl-hexanol-oxo-alcohols (plasticizers alcohol) is of high importance, being achieved through hydrogenation of 2 ethyl-hexenal inside catalytic trickle bed three-phase reactors. For this type of processes the use of advanced control strategies is suitable due to their nonlinear behavior and extreme sensitivity to load changes and other disturbances. Due to the complexity of the mathematical model an approach was to use a simple linear model of the process in combination with an advanced control algorithm which takes into account the model uncertainties, the disturbances and command signal limitations like robust control. However the resulting controller is complex, involving cost effective hardware. This paper proposes a simple integer-order control scheme using a linear model of the process, based on active disturbance rejection method. By treating the model dynamics as a common disturbance and actively rejecting it, active disturbance rejection control (ADRC) can achieve the desired response. Simulation results are provided to demonstrate the effectiveness of the proposed method

Active disturbance rejection controller for chemical reactor

Energy Technology Data Exchange (ETDEWEB)

Both, Roxana; Dulf, Eva H.; Muresan, Cristina I., E-mail: roxana.both@aut.utcluj.ro [Technical University of Cluj-Napoca, 400114 Cluj-Napoca (Romania)

2015-03-10

In the petrochemical industry, the synthesis of 2 ethyl-hexanol-oxo-alcohols (plasticizers alcohol) is of high importance, being achieved through hydrogenation of 2 ethyl-hexenal inside catalytic trickle bed three-phase reactors. For this type of processes the use of advanced control strategies is suitable due to their nonlinear behavior and extreme sensitivity to load changes and other disturbances. Due to the complexity of the mathematical model an approach was to use a simple linear model of the process in combination with an advanced control algorithm which takes into account the model uncertainties, the disturbances and command signal limitations like robust control. However the resulting controller is complex, involving cost effective hardware. This paper proposes a simple integer-order control scheme using a linear model of the process, based on active disturbance rejection method. By treating the model dynamics as a common disturbance and actively rejecting it, active disturbance rejection control (ADRC) can achieve the desired response. Simulation results are provided to demonstrate the effectiveness of the proposed method.

Optogenetic control of epileptiform activity

DEFF Research Database (Denmark)

Tønnesen, Jan; Sørensen, Andreas T; Deisseroth, Karl

2009-01-01

such an optogenetic approach using the light-driven halorhodopsin chloride pump from Natronomonas pharaonis (NpHR), modified for mammalian CNS expression to hyperpolarize central neurons, may inhibit excessive hyperexcitability and epileptiform activity. We show that a lentiviral vector containing the NpHR gene under...... that the optogenetic approach may prove useful for controlling epileptiform activity and opens a future perspective to develop it into a strategy to treat epilepsy.......The optogenetic approach to gain control over neuronal excitability both in vitro and in vivo has emerged as a fascinating scientific tool to explore neuronal networks, but it also opens possibilities for developing novel treatment strategies for neurologic conditions. We have explored whether...

Nonlinear Predictive Sliding Mode Control for Active Suspension System

Directory of Open Access Journals (Sweden)

Dazhuang Wang

2018-01-01

Full Text Available An active suspension system is important in meeting the requirements of the ride comfort and handling stability for vehicles. In this work, a nonlinear model of active suspension system and a corresponding nonlinear robust predictive sliding mode control are established for the control problem of active suspension. Firstly, a seven-degree-of-freedom active suspension model is established considering the nonlinear effects of springs and dampers; and secondly, the dynamic model is expanded in the time domain, and the corresponding predictive sliding mode control is established. The uncertainties in the controller are approximated by the fuzzy logic system, and the adaptive controller reduces the approximation error to increase the robustness of the control system. Finally, the simulation results show that the ride comfort and handling stability performance of the active suspension system is better than that of the passive suspension system and the Skyhook active suspension. Thus, the system can obviously improve the shock absorption performance of vehicles.

Differences in elongation of very long chain fatty acids and fatty acid metabolism between triple-negative and hormone receptor-positive breast cancer.

Science.gov (United States)

Yamashita, Yuji; Nishiumi, Shin; Kono, Seishi; Takao, Shintaro; Azuma, Takeshi; Yoshida, Masaru

2017-08-29

Triple-negative breast cancer (TN) is more aggressive than other subtypes of breast cancer and has a lower survival rate. Furthermore, detailed biological information about the disease is lacking. This study investigated characteristics of metabolic pathways in TN. We performed the metabolome analysis of 74 breast cancer tissues and the corresponding normal breast tissues using LC/MS. Furthermore, we classified the breast cancer tissues into ER-positive, PgR-positive, HER2-negative breast cancer (EP+H-) and TN, and then the differences in their metabolic pathways were investigated. The RT-PCR and immunostaining were carried out to examine the expression of ELOVL1, 2, 3, 4, 5, 6, and 7. We identified 142 of hydrophilic metabolites and 278 of hydrophobic lipid metabolites in breast tissues. We found the differences between breast cancer and normal breast tissues in choline metabolism, glutamine metabolism, lipid metabolism, and so on. Most characteristic of comparison between EP+H- and TN were differences in fatty acid metabolism was which were related to the elongation of very long chain fatty acids were detected between TN and EP+H-. Real-time RT-PCR showed that the mRNA expression levels of ELOVL1, 5, and 6 were significantly upregulated by 8.5-, 4.6- and 7.0-fold, respectively, in the TN tumors compared with their levels in the corresponding normal breast tissue samples. Similarly, the mRNA expression levels of ELOVL1, 5, and 6 were also significantly higher in the EP+H- tissues than in the corresponding normal breast tissues (by 4.9-, 3.4-, and 2.1-fold, respectively). The mRNA expression level of ELOVL6 was 2.6-fold higher in the TN tumors than in the EP+H- tumors. During immunostaining, the TN and EP+H- tumors demonstrated stronger ELOVL1 and 6 staining than the corresponding normal breast tissues, but ELOVL5 was not stained strongly in the TN or EP+H- tumors. Furthermore, the TN tumors exhibited stronger ELOVL1 and 6 staining than the EP+H- tumors. Marked

Dosing of Appropriate Antibiotics and Time to Administration of First Doses in the Pediatric Emergency Department.

Science.gov (United States)

Bailey, Abby M; Stephan, Maria; Weant, Kyle A; Justice, Stephanie Baker

2015-01-01

Emergency department (ED) providers are faced with the challenge of diagnosing and treating patients in a timely fashion given many obstacles including limited patient information, complex disease states, and high patient turnover. Time delays in administration or selection of appropriate drug therapies have been associated with negative outcomes in severe infections. This study was conducted to assess the impact of an emergency medicine pharmacist (EPh) on the selection of appropriate antibiotics and the timeliness of administration in pediatric patients in the ED. Patients younger than 18 years were evaluated who were admitted through the ED and received 1 dose of intravenous antibiotic for the following conditions: community-acquired pneumonia, complicated skin and soft tissue infection (SSTI), meningitis, and sepsis. To evaluate the impact of the presence of an EPh, patients with orders placed during the EPh's hours of 1 pm and 11 pm were compared to those with an order placed between 11 pm and 1 pm. A total of 142 patients were included in the study. Patients seen during EPh hours received an appropriate first antibiotic 93.4% of the time (p = 0.157) and second antibiotic 96.8% of the time (p = 0.023). Time from order to verification was significantly shorter for the first 2 antimicrobials in the EPh group (10.5 minutes [p = 0.003] and 11.4 minutes [p = 0.047], respectively). The days from discharge to return to readmission to the ED were also significantly different (17.5 days vs. 62.4 days, p = 0.008). The available data suggest that patients are more likely to receive appropriate doses of antimicrobials, and in a more timely fashion, whenever the EPh is present. Areas for future investigation include whether the presence of EPhs at the bedside has the potential to impact areas of patient care, including readmission rates, drug costs, and medication errors.

Development and validation of an UFLC-MS/MS method for enantioselectivity determination of d,l-thero-methylphenidate, d,l-thero-ethylphenidate and d,l-thero-ritalinic acid in rat plasma and its application to pharmacokinetic study.

Science.gov (United States)

Zhang, Chenghao; Luo, Huafei; Wu, Yubo; Zhang, Junyun; Zhang, Furong; Lin, Guobei; Wang, Hao

2016-02-01

A chiral UFLC-MS/MS method was established and validated for quantifying d-threo-methylphenidate (d-threo-MPH), l-threo-methylphenidate (l-threo-MPH), d-threo-ethylphenidate (d-threo-EPH), l-threo-ethylphenidate (l-threo-EPH) and d,l-threo-ritalinic acid (d,l-threo-RA) in rat plasma over the linearity range of 1-500ng/mL. Chiral separation was performed on an Astec Chirobiotic V2 column (5μm, 250×2.1mm) with isocratic elution using methanol containing 0.003% ammonium acetate (w/v) and 0.003% trifluoroacetic acid (v/v) at a flow of 0.3mL/min. All analytes and IS were extracted from rat plasma by a one-step liquid-liquid extraction (LLE) method. The intra- and inter-run accuracies were within 85-115%, and the intra- and inter-run precision were <10% for all analytes. Extraction recoveries were 55-62% for d-threo-MPH, 54-60% for l-threo-MPH, 55-60% for d-threo-EPH, 53-57% for l-threo-EPH and 25-30% for d,l-threo-RA. The validated UFLC-MS/MS method successfully applied to the pharmacokinetic interaction study of oral d-threo-MPH and l-threo-MPH (alone or in combination) in female Sprague Dawley rats. The EPH was not detected in rat plasma following oral administrated MPH without EtOH. As far as it is known to the authors, this study is the first one step liquid-liquid extraction method to extract and UFLC-MS/MS method to quantify d-threo-MPH, l-threo-MPH, d-threo-EPH, l-threo-EPH and d,l-threo-RA simultaneously. Copyright © 2015 Elsevier B.V. All rights reserved.

Active control of the noise

International Nuclear Information System (INIS)

Rodriguez V, Luis Alfonso; Lopez Q, Jose German

2001-01-01

The problems of acoustic noise are more and more preponderant in the measure in that the amount of equipment and industrial machinery is increased such as fans, transformers, compressors etc. the use of devices passive mechanics for the reduction of the noise is effective and very appreciated because its effects embrace a wide range of acoustic frequency. However, to low frequencies, such devices become too big and expensive besides that present a tendency to do not effective. The control of active noise, CAN, using the electronic generation anti-noise, constitutes an interesting solution to the problem because their operation principle allows achieving an appreciable reduction of the noise by means of the use of compact devices. The traditional techniques for the control of acoustic noise like barriers and silenced to attenuate it, are classified as passive and their works has been accepted as norm as for the treatment of problems of noise it refers. Such techniques are considered in general very effective in the attenuation of noise of wide band. However, for low frequency, the required passive structures are too big and expensive; also, their effectiveness diminishes flagrantly, that which makes them impractical in many applications. The active suppression is profiled like a practical alternative for the reduction of acoustic noise. The idea in the active treatment of the noise it contemplates the use of a device electro-acoustic, like a speaker for example that it cancels to the noise by the generation of sounds of Same width and of contrary phase (anti-noise). The cancellation phenomenon is carried out when the ant-noise combines acoustically with the noise, what is in the cancellation of both sounds. The effectiveness of the cancellation of the primary source of noise depends on the precision with which the width and the phase of the generated ant-noise are controlled. The active control of noise, ANC (activates noise control), it is being investigated for

Active versus passive screening for entrance control

International Nuclear Information System (INIS)

McCormick, N.J.

1976-01-01

The benefits of different entrance control actions are quantitatively assessed by defining a relative improvement index for the screening activity. Three classes of entrance control measures are investigated: the use of a purely active screening measure (such as a portal monitor), the use of a purely passive screening measure (such as personality typing), and the combined use of active and passive measures. Active entrance control measures have been studied previously [McCormick and Erdmann, Nucl. Mat. Manag. 4, (1975)] where it was determined that the relative improvement index is approximately related to the nondetection probability factor r for the protective system by (1-r + r ln r). It is shown here that the relative improvement index for a purely passive screening system also can be approximately expressed in a convenient manner. Because the probability is very small that a sabotage or diversion action would be attempted, the result for passive screening, multiplied by r, may be combined with the factor (1-r + r ln r) to give the relative improvement index for a combined, active-and-passive entrance control system. Results from simple example calculations indicate that passive screening of nuclear plant personnel or applicants for such positions is orders-of-magnitude less effective than portal monitors or reasonable improvements in them. 5 tables

Actively controlled shaft seals for aerospace applications

Science.gov (United States)

Salant, Richard F.

1995-07-01

This study experimentally investigates an actively controlled mechanical seal for aerospace applications. The seal of interest is a gas seal, which is considerably more compact than previous actively controlled mechanical seals that were developed for industrial use. In a mechanical seal, the radial convergence of the seal interface has a primary effect on the film thickness. Active control of the film thickness is established by controlling the radial convergence of the seal interface with a piezoelectric actuator. An actively controlled mechanical seal was initially designed and evaluated using a mathematical model. Based on these results, a seal was fabricated and tested under laboratory conditions. The seal was tested with both helium and air, at rotational speeds up to 3770 rad/sec, and at sealed pressures as high as 1.48 x 10(exp 6) Pa. The seal was operated with both manual control and with a closed-loop control system that used either the leakage rate or face temperature as the feedback. The output of the controller was the voltage applied to the piezoelectric actuator. The seal operated successfully for both short term tests (less than one hour) and for longer term tests (four hours) with a closed-loop control system. The leakage rates were typically 5-15 slm (standard liters per minute), and the face temperatures were generally maintained below 100C. When leakage rate was used as the feedback signal, the setpoint leakage rate was typically maintained within 1 slm. However, larger deviations occurred during sudden changes in sealed pressure. When face temperature was used as the feedback signal, the setpoint face temperature was generally maintained within 3 C, with larger deviations occurring when the sealed pressure changes suddenly. the experimental results were compared to the predictions from the mathematical model. The model was successful in predicting the trends in leakage rate that occurred as the balance ratio and sealed pressure changed

Modeling and control of active twist aircraft

Science.gov (United States)

Cramer, Nicholas Bryan

The Wright Brothers marked the beginning of powered flight in 1903 using an active twist mechanism as their means of controlling roll. As time passed due to advances in other technologies that transformed aviation the active twist mechanism was no longer used. With the recent advances in material science and manufacturability, the possibility of the practical use of active twist technologies has emerged. In this dissertation, the advantages and disadvantages of active twist techniques are investigated through the development of an aeroelastic modeling method intended for informing the designs of such technologies and wind tunnel testing to confirm the capabilities of the active twist technologies and validate the model. Control principles for the enabling structural technologies are also proposed while the potential gains of dynamic, active twist are analyzed.

Air traffic control activity increases attention capacity in air traffic controllers.

Science.gov (United States)

Ribas, Valdenilson Ribeiro; Martins, Hugo André de Lima; Amorim, Gutemberg Guerra; Ribas, Renata de Melo Guerra; de Almeida, Cláudia Ângela Vilela; Ribas, Valéria Ribeiro; de Vasconcelos, Carlos Augusto Carvalho; Lima, Murilo Duarte Costa; Sougey, Everton Botelho; de Castro, Raul Manhães

2010-01-01

Air traffic controllers simultaneously develop complex and multiple tasks in the course of their activities. In this context, concern is raised over the high level of attention needed by these professionals which can ultimately be affected by stress and fatigue. The objective of this study was to assess attention level in air traffic controllers (ATCo). 45 flight protection professionals were evaluated, comprising 30 ATCo, subdivided into ATCo with ten or more years in the profession (ATCo≥10, n=15) and ATCo with less than ten years in the profession (ATCo air traffic control activity after ten years may be associated with a high level of attention.

Combined Active and Reactive Power Control of Wind Farms based on Model Predictive Control

DEFF Research Database (Denmark)

Zhao, Haoran; Wu, Qiuwei; Wang, Jianhui

2017-01-01

This paper proposes a combined wind farm controller based on Model Predictive Control (MPC). Compared with the conventional decoupled active and reactive power control, the proposed control scheme considers the significant impact of active power on voltage variations due to the low X=R ratio...... of wind farm collector systems. The voltage control is improved. Besides, by coordination of active and reactive power, the Var capacity is optimized to prevent potential failures due to Var shortage, especially when the wind farm operates close to its full load. An analytical method is used to calculate...... the sensitivity coefficients to improve the computation efficiency and overcome the convergence problem. Two control modes are designed for both normal and emergency conditions. A wind farm with 20 wind turbines was used to verify the proposed combined control scheme....

Brain-Activity-Driven Real-Time Music Emotive Control

OpenAIRE

Giraldo, Sergio; Ramirez, Rafael

2013-01-01

Active music listening has emerged as a study field that aims to enable listeners to interactively control music. Most of active music listening systems aim to control music aspects such as playback, equalization, browsing, and retrieval, but few of them aim to control expressive aspects of music to convey emotions. In this study our aim is to enrich the music listening experience by allowing listeners to control expressive parameters in music performances using their perceived emotional stat...

Active controllers and the time duration to learn a task

Science.gov (United States)

Repperger, D. W.; Goodyear, C.

1986-01-01

An active controller was used to help train naive subjects involved in a compensatory tracking task. The controller is called active in this context because it moves the subject's hand in a direction to improve tracking. It is of interest here to question whether the active controller helps the subject to learn a task more rapidly than the passive controller. Six subjects, inexperienced to compensatory tracking, were run to asymptote root mean square error tracking levels with an active controller or a passive controller. The time required to learn the task was defined several different ways. The results of the different measures of learning were examined across pools of subjects and across controllers using statistical tests. The comparison between the active controller and the passive controller as to their ability to accelerate the learning process as well as reduce levels of asymptotic tracking error is reported here.

Active control: Wind turbine model

DEFF Research Database (Denmark)

Bindner, H.

1999-01-01

This report is a part of the reporting of the work done in the project 'Active Control of Wind Turbines'. This project aim is to develop a simulation model for design of control systems for turbines with pitch control and to use that model to designcontrollers. This report describes the model...... validation as well as parameter estimation. The model includes a simple model of the structure of the turbine including tower and flapwise blade bending,a detailed model of the gear box and induction generator, a linearized aerodynamic model including modelling of induction lag and actuator and sensor models...

The electrochemical Peltier heat of the standard hydrogen electrode reaction

International Nuclear Information System (INIS)

Fang Zheng; Wang Shaofen; Zhang Zhenghua; Qiu Guanzhou

2008-01-01

A method for measuring the electrochemical Peltier heat (EPH) of a single electrode reaction has been developed and an absolute scale is suggested to obtain EPH of the standard hydrogen electrode. The scale is based on φ 0 * = 0 and ΔS 0 * = 0 for any electrode reaction at zero Kelvin, in accord with the third law of thermodynamics. The relationships between entropy, enthalpy and free energy changes on this scale and on the conventional scale are derived. Calorimetric experiments were made on the Fe(CN) 6 3- /Fe(CN) 6 4- system at five different concentrations at 298.15 K, and EPH for the standard hydrogen electrode reaction is obtained. EPHs and the entropy change on the absolute scale for the studied redox are linearly related to concentration of electrolyte. The reversible electric work is almost concentration independent in the range of concentration studied

Chapter 13 - Active Rectifiers and Their Control

DEFF Research Database (Denmark)

Davari, Pooya; Zare, Firuz; Abdelhakim, Ahmed

2018-01-01

This chapter investigates the control design of active rectifiers and their applications in power electronics-based power system. The harmonic emission and measures are firstly addressed as a basis of evaluating the active rectifier's effectiveness. Furthermore, the importance of new coming...... standards is highlighted. Application-oriented design of active rectifiers as a main reason behind evolvement of different topologies is discussed. Then, the main principle in designing different control schemes in single-phase and three-phase rectifiers is investigated, analyzed, and experimentally...... verified. The influence of nonideal operating conditions with possible solutions is addressed. Finally, future prospective of active rectifiers as a one of the key enabler of carbon-free power system is summarized....

Quality control activities in the environmental radiology laboratory

International Nuclear Information System (INIS)

Llaurado, M.; Quesada, D.; Rauret, G.; Tent, J.; Zapata, D.

2006-01-01

During the last twenty years many analytical laboratories have implemented quality assurance systems. A quality system implementation requires documentation of all activities (technical and management), evaluation of these activities and its continual improvement. Implementation and adequate management of all the elements a quality system includes are not enough to guarantee quality of the analytical results generated at a time. That is the aim of a group of specific activities labelled as quality control activities. The Laboratori de Radiologia Ambiental (Environmental Radiology Laboratory; LRA) at the University of Barcelona was created in 1984 to carry out part of the quality control assays of the Environmental Radiology Monitoring Programs around some of the Spanish nuclear power plants, which are developed by the Servei Catala d'Activitats Energetiques (SCAR) and the Consejo de Seguridad Nuclear (CSN), organisations responsible for nuclear security and radiological protection. In these kind of laboratories, given the importance of the results they give, quality control activities become an essential aspect. In order to guarantee the quality of its analytical results, the LRA Direction decided to adopt the international standard UNE-EN ISO/IEC 17025 for its internal quality system and to accreditate some of the assays it carries out. In such as system, it is established, the laboratory shall monitor the validity of tests undertaken and data shall be recorded in such a way that trends are detectable. The present work shows the activities carried out in this way by the LRA, which are: Equipment control activities which in the special case of radiochemical techniques include measurement of backgrounds and blanks as well as periodical control of efficiency and resolution. Activities to assure the specifications settled by method validation, which are testing of reference materials and periodical analysis of control samples. Evaluation of the laboratory work quality

Variations in ventral root axon morphology and locomotor behavior components across different inbred strains of mice

NARCIS (Netherlands)

de Mooij-van Malsen, J. G.; Yu, K. L.; Veldman, H.; Oppelaar, H; van den Berg, L. H.; Olivier, B.; Kas, M. J. H.

2009-01-01

Locomotion is a complex behavior affected by many different brain- and spinal cord systems, as well as by variations in the peripheral nervous system. Recently, we found increased gene expression for EphA4, a gene intricately involved in motor neuron development, between high-active parental strain

A Study on Biocompatibility of Three Endodontic Sealers: Intensity and Duration of Tissue Irritation

Science.gov (United States)

Christian Gomes Moura, Camilla; Cristina Cunha, Thais; Oliveira Crema, Virgínia; Dechichi, Paula; Carlos Gabrielli Biffi, João

2014-01-01

Introduction: Several studies have evaluated the inflammatory reaction triggered by Epiphany (EPH), a contemporary endodontic sealer. However, they used conventional parameters, which need additional analysis to better understand the reactions induced by this sealer compared to other traditional sealers. Methods and Materials: The intensity and time span of tissue irritations for three endodontic sealers were assessed by inflammatory reactions, fibrous capsule measurement and mast cell counts. Tubes containing freshly mixed EPH, AH plus (AHP) and Endofill (ENF) were subcutaneously implanted into the backs of 28 Wistar rats. The side wall of the tube was used as the control. At 14, 21, 42 and 60 days, the connective tissue surrounding the implants (n=7) was stained for histopathological analysis. The Friedman test was applied to compare the results. The level of significance was set at 0.05. Results: At days 14 and 21, a significant difference among the groups was observed, with the ENF showing the worst tissue response (P<0.001). ENF remained the most aggressive sealer at 42 and 60 days, compared with EPH (P<0.05). No differences were found for the fibrous capsule thicknesses among the groups in each period. The number of mast cells per field did not show difference among the sealers at 21 and 60 days. Conclusions: EPH and AHP elicited similar patterns of irritation, as demonstrated by the inflammatory scores and fibrous capsule thicknesses. ENF caused the highest degree of tissue damage. The increase in mast cell counts observed during the early and late periods shows the possibility of late hypersensitivity to the test materials. PMID:24688584

Role of EphA4 and EphrinB3 in local neuronal circuits that control walking

DEFF Research Database (Denmark)

Kullander, Klas; Butt, Simon J B; Lebret, James M.

2003-01-01

Local circuits in the spinal cord that generate locomotion are termed central pattern generators (CPGs). These provide coordinated bilateral control over the normal limb alternation that underlies walking. The molecules that organize the mammalian CPG are unknown, isolated spinal cords from mice...

Ephrin-B3 is the midline barrier that prevents corticospinal tract axons from recrossing, allowing for unilateral motor control.

Science.gov (United States)

Kullander, K; Croll, S D; Zimmer, M; Pan, L; McClain, J; Hughes, V; Zabski, S; DeChiara, T M; Klein, R; Yancopoulos, G D; Gale, N W

2001-04-01

Growing axons follow highly stereotypical pathways, guided by a variety of attractive and repulsive cues, before establishing specific connections with distant targets. A particularly well-known example that illustrates the complexity of axonal migration pathways involves the axonal projections of motor neurons located in the motor cortex. These projections take a complex route during which they first cross the midline, then form the corticospinal tract, and ultimately connect with motor neurons in the contralateral side of the spinal cord. These obligatory contralateral connections account for why one side of the brain controls movement on the opposing side of the body. The netrins and slits provide well-known midline signals that regulate axonal crossings at the midline. Herein we report that a member of the ephrin family, ephrin-B3, also plays a key role at the midline to regulate axonal crossing. In particular, we show that ephrin-B3 acts as the midline barrier that prevents corticospinal tract projections from recrossing when they enter the spinal gray matter. We report that in ephrin-B3(-/-) mice, corticospinal tract projections freely recross in the spinal gray matter, such that the motor cortex on one side of the brain now provides bilateral input to the spinal cord. This neuroanatomical abnormality in ephrin-B3(-/-) mice correlates with loss of unilateral motor control, yielding mice that simultaneously move their right and left limbs and thus have a peculiar hopping gait quite unlike the alternate step gait displayed by normal mice. The corticospinal and walking defects in ephrin-B3(-/-) mice resemble those recently reported for mice lacking the EphA4 receptor, which binds ephrin-B3 as well as other ephrins, suggesting that the binding of EphA4-bearing axonal processes to ephrin-B3 at the midline provides the repulsive signal that prevents corticospinal tract projections from recrossing the midline in the developing spinal cord.

A reduced energy supply strategy in active vibration control

Science.gov (United States)

Ichchou, M. N.; Loukil, T.; Bareille, O.; Chamberland, G.; Qiu, J.

2011-12-01

In this paper, a control strategy is presented and numerically tested. This strategy aims to achieve the potential performance of fully active systems with a reduced energy supply. These energy needs are expected to be comparable to the power demands of semi-active systems, while system performance is intended to be comparable to that of a fully active configuration. The underlying strategy is called 'global semi-active control'. This control approach results from an energy investigation based on management of the optimal control process. Energy management encompasses storage and convenient restitution. The proposed strategy monitors a given active law without any external energy supply by considering purely dissipative and energy-demanding phases. Such a control law is offered here along with an analysis of its properties. A suboptimal form, well adapted for practical implementation steps, is also given. Moreover, a number of numerical experiments are proposed in order to validate test findings.

A reduced energy supply strategy in active vibration control

International Nuclear Information System (INIS)

Ichchou, M N; Loukil, T; Bareille, O; Chamberland, G; Qiu, J

2011-01-01

In this paper, a control strategy is presented and numerically tested. This strategy aims to achieve the potential performance of fully active systems with a reduced energy supply. These energy needs are expected to be comparable to the power demands of semi-active systems, while system performance is intended to be comparable to that of a fully active configuration. The underlying strategy is called 'global semi-active control'. This control approach results from an energy investigation based on management of the optimal control process. Energy management encompasses storage and convenient restitution. The proposed strategy monitors a given active law without any external energy supply by considering purely dissipative and energy-demanding phases. Such a control law is offered here along with an analysis of its properties. A suboptimal form, well adapted for practical implementation steps, is also given. Moreover, a number of numerical experiments are proposed in order to validate test findings

Comparative Analysis of RNAi-Based Methods to Down-Regulate Expression of Two Genes Expressed at Different Levels in Myzus persicae

Directory of Open Access Journals (Sweden)

Michaël Mulot

2016-11-01

Full Text Available With the increasing availability of aphid genomic data, it is necessary to develop robust functional validation methods to evaluate the role of specific aphid genes. This work represents the first study in which five different techniques, all based on RNA interference and on oral acquisition of double-stranded RNA (dsRNA, were developed to silence two genes, ALY and Eph, potentially involved in polerovirus transmission by aphids. Efficient silencing of only Eph transcripts, which are less abundant than those of ALY, could be achieved by feeding aphids on transgenic Arabidopsis thaliana expressing an RNA hairpin targeting Eph, on Nicotiana benthamiana infected with a Tobacco rattle virus (TRV-Eph recombinant virus, or on in vitro-synthesized Eph-targeting dsRNA. These experiments showed that the silencing efficiency may differ greatly between genes and that aphid gut cells seem to be preferentially affected by the silencing mechanism after oral acquisition of dsRNA. In addition, the use of plants infected with recombinant TRV proved to be a promising technique to silence aphid genes as it does not require plant transformation. This work highlights the need to pursue development of innovative strategies to reproducibly achieve reduction of expression of aphid genes.

Active load control techniques for wind turbines.

Energy Technology Data Exchange (ETDEWEB)

van Dam, C.P. (University of California, Davis, CA); Berg, Dale E.; Johnson, Scott J. (University of California, Davis, CA)

2008-07-01

This report provides an overview on the current state of wind turbine control and introduces a number of active techniques that could be potentially used for control of wind turbine blades. The focus is on research regarding active flow control (AFC) as it applies to wind turbine performance and loads. The techniques and concepts described here are often described as 'smart structures' or 'smart rotor control'. This field is rapidly growing and there are numerous concepts currently being investigated around the world; some concepts already are focused on the wind energy industry and others are intended for use in other fields, but have the potential for wind turbine control. An AFC system can be broken into three categories: controls and sensors, actuators and devices, and the flow phenomena. This report focuses on the research involved with the actuators and devices and the generated flow phenomena caused by each device.

Novel Active Combustion Control Valve

Science.gov (United States)

Caspermeyer, Matt

2014-01-01

This project presents an innovative solution for active combustion control. Relative to the state of the art, this concept provides frequency modulation (greater than 1,000 Hz) in combination with high-amplitude modulation (in excess of 30 percent flow) and can be adapted to a large range of fuel injector sizes. Existing valves often have low flow modulation strength. To achieve higher flow modulation requires excessively large valves or too much electrical power to be practical. This active combustion control valve (ACCV) has high-frequency and -amplitude modulation, consumes low electrical power, is closely coupled with the fuel injector for modulation strength, and is practical in size and weight. By mitigating combustion instabilities at higher frequencies than have been previously achieved (approximately 1,000 Hz), this new technology enables gas turbines to run at operating points that produce lower emissions and higher performance.

Optimisation of the RT-PCR detection of immunomagnetically enriched carcinoma cells

International Nuclear Information System (INIS)

Raynor, Michael; Stephenson, Sally-Anne; Walsh, David CA; Pittman, Kenneth B; Dobrovic, Alexander

2002-01-01

Immunomagnetic enrichment followed by RT-PCR (immunobead RT-PCR) is an efficient methodology to identify disseminated carcinoma cells in the blood and bone marrow. The RT-PCR assays must be both specific for the tumor cells and sufficiently sensitive to enable detection of single tumor cells. We have developed a method to test RT-PCR assays for any cancer. This has been investigated using a panel of RT-PCR markers suitable for the detection of breast cancer cells. In the assay, a single cell line-derived tumor cell is added to 100 peripheral blood mononuclear cells (PBMNCs) after which mRNA is isolated and reverse transcribed for RT-PCR analysis. PBMNCs without added tumor cells are used as specificity controls. The previously studied markers epidermal growth factor receptor (EGFR), mammaglobin 1 (MGB1), epithelial cell adhesion molecule (EpCAM/TACSTD1), mucin 1 (MUC1), carcinoembryonic antigen (CEA) were tested. Two new epithelial-specific markers ELF3 and EphB4 were also tested. MUC1 was unsuitable as strong amplification was detected in 100 cell PBMNC controls. Expression of ELF3, EphB4, EpCAM, EGFR, CEA and MGB1 was found to be both specific for the tumor cell, as demonstrated by the absence of a signal in most 100 cell PBMNC controls, and sensitive enough to detect a single tumor cell in 100 PBMNCs using a single round of RT-PCR. ELF3, EphB4, EpCAM, EGFR, CEA and MGB1 are appropriate RT-PCR markers for use in a marker panel to detect disseminated breast cancer cells after immunomagnetic enrichment

Active Blade Vibration Control Being Developed and Tested

Science.gov (United States)

Johnson, Dexter

2003-01-01

Gas turbine engines are currently being designed to have increased performance, lower weight and manufacturing costs, and higher reliability. Consequently, turbomachinery components, such as turbine and compressor blades, have designs that are susceptible to new vibration problems and eventual in-service failure due to high-cycle fatigue. To address this problem, researchers at the NASA Glenn Research Center are developing and testing innovative active blade vibration control concepts. Preliminary results of using an active blade vibration control system, involving a rotor supported by an active magnetic bearing in Glenn's Dynamic Spin Rig, indicate promising results (see the photograph). Active blade vibration control was achieved using feedback of blade strain gauge signals within the magnetic bearing control loop. The vibration amplitude was reduced substantially (see the graphs). Also, vibration amplitude amplification was demonstrated; this could be used to enhance structural mode identification, if desired. These results were for a nonrotating two-bladed disk. Tests for rotating blades are planned. Current and future active blade vibration control research is planned to use a fully magnetically suspended rotor and smart materials. For the fully magnetically suspended rotor work, three magnetic bearings (two radial and one axial) will be used as actuators instead of one magnetic bearing. This will allow additional degrees of freedom to be used for control. For the smart materials work, control effectors located on and off the blade will be considered. Piezoelectric materials will be considered for on-the-blade actuation, and actuator placement on a stator vane, or other nearby structure, will be investigated for off-the-blade actuation. Initial work will focus on determining the feasibility of these methods by performing basic analysis and simple experiments involving feedback control.

Vibration control of active structures an introduction

CERN Document Server

Preumont, Andre

2002-01-01

This text is an introduction to the dynamics of active structures and to the feedback control of lightly damped flexible structures. The emphasis is placed on basic issues and simple control strategies that work.

Semi Active Control of Civil Structures, Analytical and Numerical Studies

Science.gov (United States)

Kerboua, M.; Benguediab, M.; Megnounif, A.; Benrahou, K. H.; Kaoulala, F.

Structural control for civil structures was born out of a need to provide safer and more efficient designs with the reality of limited resources. The purpose of structural control is to absorb and to reflect the energy introduced by dynamic loads such as winds, waves, earthquakes, and traffic. Today, the protection of civil structures from severe dynamic loading is typically achieved by allowing the structures to be damaged. Semi-active control devices, also called "smart" control devices, assume the positive aspects of both the passive and active control devices. A semi-active control strategy is similar to the active control strategy. Only here, the control actuator does not directly apply force to the structure, but instead it is used to control the properties of a passive energy device, a controllable passive damper. Semi-active control strategies can be used in many of the same civil applications as passive and active control. One method of operating smart cable dampers is in a purely passive capacity, supplying the dampers with constant optimal voltage. The advantages to this strategy are the relative simplicity of implementing the control strategy as compared to a smart or active control strategy and that the dampers are more easily optimally tuned in- place, eliminating the need to have passive dampers with unique optimal damping coefficients. This research investigated semi-active control of civil structures for natural hazard mitigation. The research has two components, the seismic protection of buildings and the mitigation of wind-induced vibration in structures. An ideal semi-active motion equation of a composite beam that consists of a cantilever beam bonded with a PZT patch using Hamilton's principle and Galerkin's method was treated. A series R-L and a parallel R-L shunt circuits are coupled into the motion equation respectively by means of the constitutive relation of piezoelectric material and Kirchhoff's law to control the beam vibration. A

Estrés oxidativo, diabetes mellitus y enfermedad periodontal. Una revisión sistemática

Directory of Open Access Journals (Sweden)

Araceli Grizel Valdez Penagos

2004-01-01

Full Text Available La enfermedad periodontal humana (EPH es una alteración inflamatoria que incrementa el daño y pérdida de tejido, como resultado de complejas interacciones entre bacterias patogénicas y la respuesta inmune del huésped. Al mismo tiempo, ha sido señalado que la diabetes mellitus (DM incrementa la incidencia de EPH. Al respecto, las especies reactivas de oxígeno (EROs han sido implicadas en la patogénesis de ambas enfermedades. Por lo tanto, se ha hipotetizado que la mayor incidencia de EPH en los sujetos con DM en comparación con los sanos es debida al estrés oxidativo (EOx. Sin embargo, las evidencias científicas son escasas. En este artículo se presenta una revisión sistemática en relación al vínculo entre el EOx, la DM y EPH.

Strain effects on the optical conductivity of gapped graphene in the presence of Holstein phonons beyond the Dirac cone approximation

Energy Technology Data Exchange (ETDEWEB)

Yarmohammadi, Mohsen, E-mail: m.yarmohammadi69@gmail.com [Young Researchers and Elite Club, Kermanshah Branch, Islamic Azad University, Kermanshah (Iran, Islamic Republic of)

2016-08-15

In this paper we study the optical conductivity and density of states (DOS) of doped gapped graphene beyond the Dirac cone approximation in the presence of electron-phonon (e-ph) interaction under strain, i.e., within the framework of a full π-band Holstein model, by using the Kubo linear response formalism that is established upon the retarded self-energy. A new peak in the optical conductivity for a large enough e-ph interaction strength is found which is associated to transitions between the midgap states and the Van Hove singularities of the main π-band. Optical conductivity decreases with strain and at large strains, the system has a zero optical conductivity at low energies due to optically inter-band excitations through the limit of zero doping. As a result, the Drude weight changes with e-ph interaction, temperature and strain. Consequently, DOS and optical conductivity remains stable with temperature at low e-ph coupling strengths.

Elastomer Nanocomposites Based on Butadiene Rubber, Nanoclay and Epoxy-Polyester Hybrid: Microstructure and Mechanical Properties

Directory of Open Access Journals (Sweden)

Sepideh Zoghi

2013-08-01

Full Text Available Nanocomposites based on butadiene rubber (BR, (0, 3, 5 and 7 phr organoclay (Cloisite 15A and (0, 10, 20, 30, 40 phr powder coating wastes, i.e., epoxypolyester hybrid (EPH were prepared using a laboratory-scale internal mixer in order to study the effect of organoclay and EPH content on the mechanical and morphological properties of the nanocomposite samples. Cure characteristics of the prepared compounds including optimum cure time (t90 and scorch time (t5 depicted a decrease in both mentioned factors with increasing nanoclay content and EPH loading.Intercalation of elastomer chains into the silicate layers was determined by d-spacing values calculated according to the results of X-ray diffraction (XRD patterns. X-ray diffraction (XRD results reveal the intercalation of elastomer chains into the clay galleries. This phenomenon was also confirmed according to the scanning electron microscopy (SEM micrographs and mechanical properties of the nanocomposite samples which were observed to be improved with addition of nanoclay and EPH content.

Quality control of the activity meter

International Nuclear Information System (INIS)

Rodrigues, Marlon da Silva Brandão; Sá, Lídia Vasconcelos de

2017-01-01

Objective: To carry out a comparative analysis of national and international standards regarding the quality control of the activity meter used in Nuclear Medicine Services in Brazil. Material and methods: Quality control protocols from the International Atomic Energy Agency (IAEA), American Association of Physicists in Medicine (AAPM) and International Electrotechnical Commission (IEC) were pointed out and compared with requirements from both regulatory Brazilian agencies, National Surveillance Agency (ANVISA) and National Nuclear Energy Commission (CNEN). Results: The daily routine tests recommended by the regulatory agencies do not have significant differences; in contrast the tests with higher periodicities like (accuracy, linearity and precision) have differences discrepant. Conclusion: In view of the comparative analysis carried out, it is suggested that the national recommendations for the quality control tests of the activity meter should be checked and evaluated, with emphasis on the semiannual and annual periodicity tests. (author)

Active noise control technique and its application on ships

Directory of Open Access Journals (Sweden)

CHEN Kean

2017-08-01

Full Text Available Due to the rapid development during past three decades, Active Noise Control(ANC has become a highly complementary noise control approach in comparison with traditional approaches, and has formed a complete system including basic theory, investigation approach, key techniques and system implementation. Meanwhile, substantial progress has been achieved in such fields as the practical application, industrialization development and commercial popularization of ANC, and this developed technique provides a practical and feasible choice for the active control of ship noise. In this review paper, its sound field analysis, system setup and key techniques are summarized, typical examples of ANC-based engineering applications including control of cabin noise and duct noise are briefly described, and a variety of forefronts and problems associated with the applications of ANC in ship noise control, such as active sound absorption, active sound insulation and smart acoustic structure, are subsequently discussed.

Activities of the control services; Activites des services du controle

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-12-31

This paper summarizes the control activities of the technical service of electric power and big dams: annual examinations, administrative instructions (draining, floods, granting renewal), decennial examinations etc. (J.S.)

Active structural control with stable fuzzy PID techniques

CERN Document Server

Yu, Wen

2016-01-01

This book presents a detailed discussion of intelligent techniques to measure the displacement of buildings when they are subjected to vibration. It shows how these techniques are used to control active devices that can reduce vibration 60–80% more effectively than widely used passive anti-seismic systems. After introducing various structural control devices and building-modeling and active structural control methods, the authors propose offset cancellation and high-pass filtering techniques to solve some common problems of building-displacement measurement using accelerometers. The most popular control algorithms in industrial settings, PD/PID controllers, are then analyzed and then combined with fuzzy compensation. The stability of this combination is proven with standard weight-training algorithms. These conditions provide explicit methods for selecting PD/PID controllers. Finally, fuzzy-logic and sliding-mode control are applied to the control of wind-induced vibration. The methods described are support...

Active structural acoustic control of helicopter interior multifrequency noise using input-output-based hybrid control

Science.gov (United States)

Ma, Xunjun; Lu, Yang; Wang, Fengjiao

2017-09-01

This paper presents the recent advances in reduction of multifrequency noise inside helicopter cabin using an active structural acoustic control system, which is based on active gearbox struts technical approach. To attenuate the multifrequency gearbox vibrations and resulting noise, a new scheme of discrete model predictive sliding mode control has been proposed based on controlled auto-regressive moving average model. Its implementation only needs input/output data, hence a broader frequency range of controlled system is modelled and the burden on the state observer design is released. Furthermore, a new iteration form of the algorithm is designed, improving the developing efficiency and run speed. To verify the algorithm's effectiveness and self-adaptability, experiments of real-time active control are performed on a newly developed helicopter model system. The helicopter model can generate gear meshing vibration/noise similar to a real helicopter with specially designed gearbox and active struts. The algorithm's control abilities are sufficiently checked by single-input single-output and multiple-input multiple-output experiments via different feedback strategies progressively: (1) control gear meshing noise through attenuating vibrations at the key points on the transmission path, (2) directly control the gear meshing noise in the cabin using the actuators. Results confirm that the active control system is practical for cancelling multifrequency helicopter interior noise, which also weakens the frequency-modulation of the tones. For many cases, the attenuations of the measured noise exceed the level of 15 dB, with maximum reduction reaching 31 dB. Also, the control process is demonstrated to be smoother and faster.

Active vibration control using state space LQG and internal model control methods

DEFF Research Database (Denmark)

Mørkholt, Jakob; Elliott, S.J.

1998-01-01

Two ways of designing discrete time robust H2-controllers for feedback broadband active vibration control are compared through computer simulations. The methods are based on different models of disturbance and plant transfer functions, but yield controllers with identical properties. Two simple...... ways of introducing robustness into the H2-design are compared, and finally an efficient way of designing a practical IIR-controller is proposed....

Goal-congruent default network activity facilitates cognitive control.

Science.gov (United States)

Spreng, R Nathan; DuPre, Elizabeth; Selarka, Dhawal; Garcia, Juliana; Gojkovic, Stefan; Mildner, Judith; Luh, Wen-Ming; Turner, Gary R

2014-10-15

Substantial neuroimaging evidence suggests that spontaneous engagement of the default network impairs performance on tasks requiring executive control. We investigated whether this impairment depends on the congruence between executive control demands and internal mentation. We hypothesized that activation of the default network might enhance performance on an executive control task if control processes engage long-term memory representations that are supported by the default network. Using fMRI, we scanned 36 healthy young adult humans on a novel two-back task requiring working memory for famous and anonymous faces. In this task, participants (1) matched anonymous faces interleaved with anonymous face, (2) matched anonymous faces interleaved with a famous face, or (3) matched a famous faces interleaved with an anonymous face. As predicted, we observed a facilitation effect when matching famous faces, compared with anonymous faces. We also observed greater activation of the default network during these famous face-matching trials. The results suggest that activation of the default network can contribute to task performance during an externally directed executive control task. Our findings provide evidence that successful activation of the default network in a contextually relevant manner facilitates goal-directed cognition. Copyright © 2014 the authors 0270-6474/14/3414108-07$15.00/0.

Analysis and control of a shunt active power filter

Energy Technology Data Exchange (ETDEWEB)

Ottersten, R.; Petersson, Andreas [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Electric Power Engineering

1999-09-01

This report deals with active power filtering of low-frequency current harmonics. The active filter consists of a forced-commutated voltage source inverter with a digital control system. The aim of this master thesis is to investigate the performance of a shunt active power filter, and the parameters influence on the system performance. Three different harmonic identification methods are presented and compared. The shunt active power filter is very well suited for harmonic current reduction, provided that the phase shift due to the digital implementation of the control system is compensated. The performance of the active power filter depends on the switching frequency. When using individual harmonic detection methods the amount of compensation can be fully controlled for each current harmonic.

Jacket Substructure Fatigue Mitigation through Active Control

DEFF Research Database (Denmark)

Hanis, Tomas; Natarajan, Anand

2014-01-01

to the fatigue design loads on the braces of the jacket. Since large wind turbines of 10MW rating have low rotor speeds (p), the modal frequencies of the sub structures approach 3p at low wind speeds, which leads to a modal coupling and resonance. Therefore an active control system is developed which provides...... sufficient structural damping and consequently a fatigue reduction at the substructure. The resulting reduction in fatigue design loads on the jacket structure based on the active control system is presented....

Active control of sound transmission through partitions composed of discretely controlled modules

Science.gov (United States)

Leishman, Timothy W.

This thesis provides a detailed theoretical and experimental investigation of active segmented partitions (ASPs) for the control of sound transmission. ASPs are physically segmented arrays of interconnected acoustically and structurally small modules that are discretely controlled using electronic controllers. Theoretical analyses of the thesis first address physical principles fundamental to ASP modeling and experimental measurement techniques. Next, they explore specific module configurations, primarily using equivalent circuits. Measured normal-incidence transmission losses and related properties of experimental ASPs are determined using plane wave tubes and the two-microphone transfer function technique. A scanning laser vibrometer is also used to evaluate distributed transmitting surface vibrations. ASPs have the inherent potential to provide excellent active sound transmission control (ASTC) through lightweight structures, using very practical control strategies. The thesis analyzes several unique ASP configurations and evaluates their abilities to produce high transmission losses via global minimization of normal transmitting surface vibrations. A novel dual diaphragm configuration is shown to employ this strategy particularly well. It uses an important combination of acoustical actuation and mechano-acoustical segmentation to produce exceptionally high transmission loss (e.g., 50 to 80 dB) over a broad frequency range-including lower audible frequencies. Such performance is shown to be comparable to that produced by much more massive partitions composed of thick layers of steel or concrete and sand. The configuration uses only simple localized error sensors and actuators, permitting effective use of independent single-channel controllers in a decentralized format. This work counteracts the commonly accepted notion that active vibration control of partitions is an ineffective means of controlling sound transmission. With appropriate construction, actuation

Formal Verification of Effectiveness of Control Activities in Business Processes

Science.gov (United States)

Arimoto, Yasuhito; Iida, Shusaku; Futatsugi, Kokichi

It has been an important issue to deal with risks in business processes for achieving companies' goals. This paper introduces a method for applying a formal method to analysis of risks and control activities in business processes in order to evaluate control activities consistently, exhaustively, and to give us potential to have scientific discussion on the result of the evaluation. We focus on document flows in business activities and control activities and risks related to documents because documents play important roles in business. In our method, document flows including control activities are modeled and it is verified by OTS/CafeOBJ Method that risks about falsification of documents are avoided by control activities in the model. The verification is done by interaction between humans and CafeOBJ system with theorem proving, and it raises potential to discuss the result scientifically because the interaction gives us rigorous reasons why the result is derived from the verification.

Active Disturbance Rejection Approach for Robust Fault-Tolerant Control via Observer Assisted Sliding Mode Control

Directory of Open Access Journals (Sweden)

John Cortés-Romero

2013-01-01

Full Text Available This work proposes an active disturbance rejection approach for the establishment of a sliding mode control strategy in fault-tolerant operations. The core of the proposed active disturbance rejection assistance is a Generalized Proportional Integral (GPI observer which is in charge of the active estimation of lumped nonlinear endogenous and exogenous disturbance inputs related to the creation of local sliding regimes with limited control authority. Possibilities are explored for the GPI observer assisted sliding mode control in fault-tolerant schemes. Convincing improvements are presented with respect to classical sliding mode control strategies. As a collateral advantage, the observer-based control architecture offers the possibility of chattering reduction given that a significant part of the control signal is of the continuous type. The case study considers a classical DC motor control affected by actuator faults, parametric failures, and perturbations. Experimental results and comparisons with other established sliding mode controller design methodologies, which validate the proposed approach, are provided.

Modelling genetic reorganization in the mouse spinal cord affecting left-right coordination during locomotion

DEFF Research Database (Denmark)

Rybak, Ilya A.; Shevtsova, Natalia A.; Kiehn, Ole

2013-01-01

glutamatergic interneurons, whose axon guidance involves the EphA4 receptor. In EphA4 knockout (KO) and Netrin-1 KO mice, the normal left-right alternating pattern is replaced with a synchronized hopping gait, and the cord of DCC KO mice exhibits uncoordinated left and right oscillations. To investigate...

Simulation model of an active-stall fixed-speed wind turbine controller

Energy Technology Data Exchange (ETDEWEB)

Jauch, C.; Hansen, A.D.; Sorensen, P.; Blaabjerg, F.

2004-07-01

This paper describes an active-stall wind turbine controller. The objective is to develop a general model of an active stall controller in order to simulate the operation of grid connected active stall wind turbines. The active stall turbine concept and its control strategies are presented and evaluated by simulations. The presented controller is described for continuous operation under all wind speeds from start-up wind speed to shut down wind speed. Due to its parametric implementation it is general i. e. it can represent different active stall wind turbine controllers and can be implemented in different simulation tools. (author)

Distributed Model Predictive Control for Active Power Control of Wind Farm

DEFF Research Database (Denmark)

Zhao, Haoran; Wu, Qiuwei; Rasmussen, Claus Nygaard

2014-01-01

This paper presents the active power control of a wind farm using the Distributed Model Predictive Controller (D- MPC) via dual decomposition. Different from the conventional centralized wind farm control, multiple objectives such as power reference tracking performance and wind turbine load can...... be considered to achieve a trade-off between them. Additionally, D- MPC is based on communication among the subsystems. Through the interaction among the neighboring subsystems, the global optimization could be achieved, which significantly reduces the computation burden. It is suitable for the modern large......-scale wind farm control....

Experience with ActiveX control for simple channel access

International Nuclear Information System (INIS)

Timossi, C.; Nishimura, H.; McDonald, J.

2003-01-01

Accelerator control system applications at Berkeley Lab's Advanced Light Source (ALS) are typically deployed on operator consoles running Microsoft Windows 2000 and utilize EPICS[2]channel access for data access. In an effort to accommodate the wide variety of Windows based development tools and developers with little experience in network programming, ActiveX controls have been deployed on the operator stations. Use of ActiveX controls for use in the accelerator control environment has been presented previously[1]. Here we report on some of our experiences with the use and development of these controls

Effects of the temperature and pressure on the electronic and optical properties of an exciton in GaAs/Ga1-xAlxAs quantum ring

Science.gov (United States)

El-Bakkari, K.; Sali, A.; Iqraoun, E.; Rezzouk, A.; Es-Sbai, N.; Ouazzani Jamil, M.

2018-06-01

Using a variational approach, we have calculated the binding energies (E1s,2sb) and interband emission energy (Eph) of an exciton confined in GaAs / Ga1 - x Alx As quantum rings (QRs) structures under effects of the temperature and pressure, in the effective mass approximation. We have taken into consideration the difference in the effective masses of the charge carriers in two materials, well and barrier. The results that we have obtained show clearly that E1s,2sb and Eph are influenced by the structure geometries of QR (height H, radial thickness Δ R and potential barrier), the temperature and pressure. Indeed, with a smaller geometric parameter, E1s,2sb and Eph become higher due to the improvement in confinement of the charge carriers. We have also observed that for a given value of the temperature, the pressure leads to an increasing of the E1s,2sb and Eph , and the latter quantities are decreasing with temperature. In addition, these variations of the E1s,2sb and Eph under the external perturbations are more remarkable in small H for fixed Δ R , and for larger Δ R for a given value of the H, because for the choice of a finite height of the barrier in the z direction and an infinite confinement in ρ direction.

Emergency peripartum hysterectomy in the Dubai health system: A fifteen year experience.

Science.gov (United States)

Tahlak, Muna Abdulrazzaq; Abdulrahman, Mahera; Hubaishi, Nawal Mahmood; Omar, Mushtaq; Cherifi, Fatima; Magray, Shazia; Carrick, Frederick Robert

2018-03-01

To determine the incidence, demographic data, risk factors, indications, outcome and complications of emergency peripartum hysterectomy (EPH) performed in two major tertiary care hospitals in Dubai, and to compare the results with the literature. The records of all women who underwent EPH from January 2000 to December 2015 in two major tertiary care hospitals in Dubai were accessed and reviewed. Maternal characteristics, hysterectomy indications, outcomes, and postoperative complications were recorded using descriptive statistics to describe the cohort. There were 79 EPH out of 168.293 deliveries, a rate of 0.47/1000 deliveries. The most common indications for hysterectomy were abnormal placentation (previa and/or accreta) and uterine atony. The majority of hysterectomies were subtotal (70%). The complications were dominated by massive transfusion, urinary tract injuries, one case of maternal death, and one case of neonatal death. The main indication for EPH was abnormal placentation in scarred uterus and uterine atony. The major method of prevention of EPH is to assess women's risks and to reduce the number of cesarean section deliveries, by limiting the rate of primary cesareans. This is challenging in the United Arab Emirates (UAE) where the culture is for high gravidity and high parity. Recommendations to act to reduce primary and repeated cesareans should be included on the national agenda in UAE.

Pivoting output unit control systems activated by jacks. [for controlling aircraft flaps

Science.gov (United States)

Belliere, P.

1978-01-01

An invention to be used for controlling aircraft flaps is described. It is applicable to control systems with two coaxial output units which pivot simultaneously with respect to two fixed units and which are activated by two opposed, straight coaxial jacks.

Validation of reported physical activity for cholesterol control using two different physical activity instruments

Directory of Open Access Journals (Sweden)

Amy Z Fan

2009-08-01

Full Text Available Amy Z Fan1, Sandra A Ham2, Shravani Reddy Muppidi3, Ali H Mokdad41Behavioral Surveillance Branch, Division of Adult and Community Health, National Center for Chronic Disease Prevention and Health Promotion; 2Physical Activity and Health Branch, Division of Nutrition, Physical Activity, and Obesity, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, Atlanta, GA, USA; 3College of Public Health, University of Georgia, Athens, GA, USA; 4Institute for Health Metrics and Evaluation, University of Washington, Seattle, WA, USAAbstract: The National Cholesterol Education Program recommends increasing physical activity to improve cholesterol levels and overall cardiovascular health. We examined whether US adults who reported increasing their physical activity to control or lower blood cholesterol following physician’s advice or on their own efforts had higher levels of physical activity than those who reported that they did not. We used data from the National Health and Nutrition Examination Survey 2003–2004, which implemented two physical activity assessment instruments. The physical activity questionnaire (PAQ assessed self-reported frequency, intensity, and duration of leisure-time, household, and transportation-related physical activity in the past month. Physical movement was objectively monitored using a waist accelerometer that assessed minute-by-minute intensity (counts of movement/minute during waking time over a 7-day period. We adjusted our analysis for age, gender, race/ethnicity, educational attainment, and body mass index. Participants who reported increasing physical activity to control blood cholesterol had more PAQ-assessed physical activity and more accelerometer-assessed active days per week compared to those who did not. However, there were no significant differences in cholesterol levels between comparison groups. These findings suggest that self-report of exercising

Exercising self-control increases relative left frontal cortical activation.

Science.gov (United States)

Schmeichel, Brandon J; Crowell, Adrienne; Harmon-Jones, Eddie

2016-02-01

Self-control refers to the capacity to override or alter a predominant response tendency. The current experiment tested the hypothesis that exercising self-control temporarily increases approach motivation, as revealed by patterns of electrical activity in the prefrontal cortex. Participants completed a writing task that did vs did not require them to exercise self-control. Then they viewed pictures known to evoke positive, negative or neutral affect. We assessed electroencephalographic (EEG) activity while participants viewed the pictures, and participants reported their trait levels of behavioral inhibition system (BIS) and behavioral activation system (BAS) sensitivity at the end of the study. We found that exercising (vs not exercising) self-control increased relative left frontal cortical activity during picture viewing, particularly among individuals with relatively higher BAS than BIS, and particularly during positive picture viewing. A similar but weaker pattern emerged during negative picture viewing. The results suggest that exercising self-control temporarily increases approach motivation, which may help to explain the aftereffects of self-control (i.e. ego depletion). © The Author (2015). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

Active control: Wind turbine model

Energy Technology Data Exchange (ETDEWEB)

Bindner, Henrik

1999-07-01

This report is a part of the reporting of the work done in the project `Active Control of Wind Turbines`. This project aim is to develop a simulation model for design of control systems for turbines with pitch control and to use that model to design controllers. This report describes the model developed for controller design and analysis. Emphasis has been put on establishment of simple models describing the dynamic behavior of the wind turbine in adequate details for controller design. This has been done with extensive use of measurements as the basis for selection of model complexity and model validation as well as parameter estimation. The model includes a simple model of the structure of the turbine including tower and flapwise blade bending, a detailed model of the gear box and induction generator, a linearized aerodynamic model including modelling of induction lag and actuator and sensor models. The models are all formulated as linear differential equations. The models are validated through comparisons with measurements performed on a Vestas WD 34 400 kW wind turbine. It is shown from a control point of view simple linear models can be used to describe the dynamic behavior of a pitch controlled wind turbine. The model and the measurements corresponds well in the relevant frequency range. The developed model is therefore applicable for controller design. (au) EFP-91. 18 ills., 22 refs.

A new robust adaptive controller for vibration control of active engine mount subjected to large uncertainties

International Nuclear Information System (INIS)

Fakhari, Vahid; Choi, Seung-Bok; Cho, Chang-Hyun

2015-01-01

This work presents a new robust model reference adaptive control (MRAC) for vibration control caused from vehicle engine using an electromagnetic type of active engine mount. Vibration isolation performances of the active mount associated with the robust controller are evaluated in the presence of large uncertainties. As a first step, an active mount with linear solenoid actuator is prepared and its dynamic model is identified via experimental test. Subsequently, a new robust MRAC based on the gradient method with σ-modification is designed by selecting a proper reference model. In designing the robust adaptive control, structured (parametric) uncertainties in the stiffness of the passive part of the mount and in damping ratio of the active part of the mount are considered to investigate the robustness of the proposed controller. Experimental and simulation results are presented to evaluate performance focusing on the robustness behavior of the controller in the face of large uncertainties. The obtained results show that the proposed controller can sufficiently provide the robust vibration control performance even in the presence of large uncertainties showing an effective vibration isolation. (paper)

Active Inference, homeostatic regulation and adaptive behavioural control.

Science.gov (United States)

Pezzulo, Giovanni; Rigoli, Francesco; Friston, Karl

2015-11-01

We review a theory of homeostatic regulation and adaptive behavioural control within the Active Inference framework. Our aim is to connect two research streams that are usually considered independently; namely, Active Inference and associative learning theories of animal behaviour. The former uses a probabilistic (Bayesian) formulation of perception and action, while the latter calls on multiple (Pavlovian, habitual, goal-directed) processes for homeostatic and behavioural control. We offer a synthesis these classical processes and cast them as successive hierarchical contextualisations of sensorimotor constructs, using the generative models that underpin Active Inference. This dissolves any apparent mechanistic distinction between the optimization processes that mediate classical control or learning. Furthermore, we generalize the scope of Active Inference by emphasizing interoceptive inference and homeostatic regulation. The ensuing homeostatic (or allostatic) perspective provides an intuitive explanation for how priors act as drives or goals to enslave action, and emphasises the embodied nature of inference. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Thermal stress mitigation by Active Thermal Control

DEFF Research Database (Denmark)

Soldati, Alessandro; Dossena, Fabrizio; Pietrini, Giorgio

2017-01-01

This work proposes an Active Thermal Control (ATC) of power switches. Leveraging on the fact that thermal stress has wide impact on the system reliability, controlling thermal transients is supposed to lengthen the lifetime of electronic conversion systems. Indeed in some environments...... results of control schemes are presented, together with evaluation of the proposed loss models. Experimental proof of the ability of the proposed control to reduce thermal swing and related stress on the device is presented, too....

A cluster randomized control trial to assess the impact of active learning on child activity, attention control, and academic outcomes: The Texas I-CAN trial.

Science.gov (United States)

Bartholomew, John B; Jowers, Esbelle M; Errisuriz, Vanessa L; Vaughn, Sharon; Roberts, Gregory

2017-10-01

Active learning is designed to pair physical activity with the teaching of academic content. This has been shown to be a successful strategy to increase physical activity and improve academic performance. The existing designs have confounded academic lessons with physical activity. As a result, it is impossible to determine if the subsequent improvement in academic performance is due to: (1) physical activity, (2) the academic content of the active learning, or (3) the combination of academic material taught through physical activity. The Texas I-CAN project is a 3-arm, cluster randomized control trial in which 28 elementary schools were assigned to either control, math intervention, or spelling intervention. As a result, each intervention condition serves as an unrelated content control for the other arm of the trial, allowing the impact of physical activity to be separated from the content. That is, schools that perform only active math lessons provide a content control for the spelling schools on spelling outcomes. This also calculated direct observations of attention and behavior control following periods of active learning. This design is unique in its ability to separate the impact of physical activity, in general, from the combination of physical activity and specific academic content. This, in combination with the ability to examine both proximal and distal outcomes along with measures of time on task will do much to guide the design of future, school-based interventions. Copyright © 2017 Elsevier Inc. All rights reserved.

Coherent active polarization control without loss

Science.gov (United States)

Ye, Yuqian; Hay, Darrick; Shi, Zhimin

2017-11-01

We propose a lossless active polarization control mechanism utilizing an anisotropic dielectric medium with two coherent inputs. Using scattering matrix analysis, we derive analytically the required optical properties of the anisotropic medium that can behave as a switchable polarizing beam splitter. We also show that such a designed anisotropic medium can produce linearly polarized light at any azimuthal direction through coherent control of two inputs with a specific polarization state. Furthermore, we present a straightforward design-on-demand procedure of a subwavelength-thick metastructure that can possess the desired optical anisotropy at a flexible working wavelength. Our lossless coherent polarization control technique may lead to fast, broadband and integrated polarization control elements for applications in imaging, spectroscopy, and telecommunication.

Active vibration control for piezoelectricity cantilever beam: an adaptive feedforward control method

Science.gov (United States)

Zhu, Qiao; Yue, Jun-Zhou; Liu, Wei-Qun; Wang, Xu-Dong; Chen, Jun; Hu, Guang-Di

2017-04-01

This work is focused on the active vibration control of piezoelectric cantilever beam, where an adaptive feedforward controller (AFC) is utilized to reject the vibration with unknown multiple frequencies. First, the experiment setup and its mathematical model are introduced. Due to that the channel between the disturbance and the vibration output is unknown in practice, a concept of equivalent input disturbance (EID) is employed to put an equivalent disturbance into the input channel. In this situation, the vibration control can be achieved by setting the control input be the identified EID. Then, for the EID with known multiple frequencies, the AFC is introduced to perfectly reject the vibration but is sensitive to the frequencies. In order to accurately identify the unknown frequencies of EID in presence of the random disturbances and un-modeled nonlinear dynamics, the time-frequency-analysis (TFA) method is employed to precisely identify the unknown frequencies. Consequently, a TFA-based AFC algorithm is proposed to the active vibration control with unknown frequencies. Finally, four cases are given to illustrate the efficiency of the proposed TFA-based AFC algorithm by experiment.

Active Control of Parametric Vibrations in Coupled Rotor-Blade Systems

DEFF Research Database (Denmark)

Christensen, Rene Hardam; Santos, Ilmar

2003-01-01

of modes. The designed control scheme is applied to a coupled rotor-blade system and dynamic responses are numerically evaluated. Such responses show that the vibrations are efficiently reduced. Frequency response diagrams demonstrate that both basis and parametric vibration modes are significantly...... the model becomes periodic-variant. In order to reduce basis as well as parametric vibrations by means of active control in such systems a time-variant control strategy has to be adopted. This paper presents a methodology for designing an active controller to reduce vibrations in a coupled rotor......-blade system. The main aim is to control blade as well as hub vibrations in such a system by means of active control with focus on reducing the parametric vibration. A periodic state feedback controller is designed by transforming the system into a linear time-invariant form. Using this a controller...

Optimal integral force feedback for active vibration control

Science.gov (United States)

Teo, Yik R.; Fleming, Andrew J.

2015-11-01

This paper proposes an improvement to Integral Force Feedback (IFF), which is a popular method for active vibration control of structures and mechanical systems. Benefits of IFF include robustness, guaranteed stability and simplicity. However, the maximum damping performance is dependent on the stiffness of the system; hence, some systems cannot be adequately controlled. In this paper, an improvement to the classical force feedback control scheme is proposed. The improved method achieves arbitrary damping for any mechanical system by introducing a feed-through term. The proposed improvement is experimentally demonstrated by actively damping an objective lens assembly for a high-speed confocal microscope.

Cloning and characterization of an epoxide hydrolase-encoding gene from Rhodotorula glutinis

NARCIS (Netherlands)

Visser, H.; Vreugdenhil, S.; Bont, de J.A.M.; Verdoes, J.C.

2000-01-01

We cloned and characterized the epoxide hydrolase gene, EPH1, from Rhodotorula glutinis. The EPH1 open reading frame of 1230 bp was interrupted by nine introns and encoded a polypeptide of 409 amino acids with a calculated molecular mass of 46.3 kDa. The amino acid sequence was similar to that of

Relationships among providing maternal, child, and adolescent health services; implementing various financial strategy responses; and performance of local health departments.

Science.gov (United States)

Issel, L Michele; Olorunsaiye, Comfort; Snebold, Laura; Handler, Arden

2015-04-01

We explored the relationships between local health department (LHD) structure, capacity, and macro-context variables and performance of essential public health services (EPHS). In 2012, we assessed a stratified, random sample of 195 LHDs that provided data via an online survey regarding performance of EPHS, the services provided or contracted out, the financial strategies used in response to budgetary pressures, and the extent of collaborations. We performed weighted analyses that included analysis of variance, pairwise correlations by jurisdiction population size, and linear regressions. On average, LHDs provided approximately 13 (36%) of 35 possible services either directly or by contract. Rather than cut services or externally consolidating, LHDs took steps to generate more revenue and maximize capacity. Higher LHD performance of EPHS was significantly associated with delivering more services, initiating more financial strategies, and engaging in collaboration, after adjusting for the effects of the Affordable Care Act and jurisdiction size. During changing economic and health care environments, we found that strong structural capacity enhanced local health department EPHS performance for maternal, child, and adolescent health.

Shippingport Station Decommissioning Project (SSDP): configuration control system and project activity controls

International Nuclear Information System (INIS)

Mullee, G.R.

1986-01-01

The SSDP has been using a Configuration Control system as a significant element in the management plan for the safe and effective performance of the project. The objective of the Configuration Control system is to control the physical plant configuration, system status, work schedules, status tracking, and day-to-day problem resolution. Prior to the Decommissioning Operations Contractor (DOC) assuming operational responsibility for the Shippingport Plant, an assessment was made of the status of the configuration of the systems and related documentation. Action was taken as required to match the operating procedures and system documentation with the actual physical condition of the plant. During the first stage of the project, planning was put in place for subsequent decommissioning activities. This planning included defining organizational responsibilities, completing the necessary project instructions and procedures, and doing the planning and scheduling for the subsequent decommissioning phase activities. Detailed instructions for the performance of the various decommissioning tasks were prepared. Prior to the start of any work on a given Activity Package, a Work Authorization is required. The Work Authorization form provides a complete checklist to ensure that all necessary prerequisites are completed. A computerized Communications Configuration Control Information system monitors status including information on system status, tag-outs, radiological work permits, etc. An ongoing effort is being directed toward maintaining operating instructions and system schematics, etc. current as the Plant configuration changes. The experience with the Configuration Control System to date has been favorable

Wireless sensor networks for active vibration control in automobile structures

International Nuclear Information System (INIS)

Mieyeville, Fabien; Navarro, David; Du, Wan; Ichchou, Mohamed; Scorletti, Gérard

2012-01-01

Wireless sensor networks (WSNs) are nowadays widely used in monitoring and tracking applications. This paper presents the feasibility of using WSNs in active vibration control strategies. The method employed here involves active-structural acoustic control using piezoelectric sensors distributed on a car structure. This system aims at being merged with a WSN whose head node collects data and processes control laws so as to command piezoelectric actuators wisely placed on the structure. We will study the feasibility of implementing WSNs in active vibration control and introduce a complete design methodology to optimize hardware/software and control law synergy in mechatronic systems. A design space exploration will be conducted so as to identify the best WSN platform and the resulting impact on control. (paper)

Dynamics of electrons and holes at surfaces

International Nuclear Information System (INIS)

Chulkov, E.V.; Leonardo, A.; Sklyadneva, I.Yu.; Silkin, V.M.

2007-01-01

We present ab initio calculation results for electron-phonon (e-ph) contribution to hole lifetime broadening of the X-bar surface state on Al(0 0 1). We show that e-ph coupling in this state is significantly stronger than in bulk Al at the Fermi level. It makes the e-ph decay channel very important in the formation of the hole decay in the surface state at X-bar. We also present the results for e-e lifetime broadening in a quantum-well state in 1 ML K/Cu(1 1 1). We show that this contribution is not negligible and is much larger than that in a surface state on Ag(1 1 1)

Quality control of the documentation process in electronic economic activities

Directory of Open Access Journals (Sweden)

Krutova A.S.

2017-06-01

Full Text Available It is proved that the main tool that will provide adequate information resources e economic activities of social and economic relations are documenting quality control processes as the basis of global information space. Directions problems as formation evaluation information resources in the process of documentation, namely development tools assess the efficiency of the system components – qualitative assessment; development of mathematical modeling tools – quantitative evaluation. A qualitative assessment of electronic documentation of economic activity through exercise performance, efficiency of communication; document management efficiency; effectiveness of flow control operations; relationship management effectiveness. The concept of quality control process documents electronically economic activity to components which include: the level of workflow; forms adequacy of information; consumer quality documents; quality attributes; type of income data; condition monitoring systems; organizational level process documentation; attributes of quality, performance quality consumer; type of management system; type of income data; condition monitoring systems. Grounded components of the control system electronic document subjects of economic activity. Detected components IT-audit management system economic activity: compliance audit; audit of internal control; detailed multilevel analysis; corporate risk assessment methodology. The stages and methods of processing electronic transactions economic activity during condition monitoring of electronic economic activity.

DSP Control of Line Hybrid Active Filter

DEFF Research Database (Denmark)

Dan, Stan George; Benjamin, Doniga Daniel; Magureanu, R.

2005-01-01

Active Power Filters have been intensively explored in the past decade. Hybrid active filters inherit the efficiency of passive filters and the improved performance of active filters, and thus constitute a viable improved approach for harmonic compensation. In this paper a parallel hybrid filter...... is studied for current harmonic compensation. The hybrid filter is formed by a single tuned Le filter and a small-rated power active filter, which are directly connected in series without any matching transformer. Thus the required rating of the active filter is much smaller than a conventional standalone...... active filter. Simulation and experimental results obtained in laboratory confirmed the validity and effectiveness of the control....

Development of hydraulic brake actuator for active brake control; Active brake seigyoyo yuatsu booster no kaihatsu

Energy Technology Data Exchange (ETDEWEB)

Konishi, Y; Hattori, M. Sugisawa, M.; Nishii, M [Aisin Seiki Co. Ltd., Aichi (Japan)

1997-10-01

Recently, application of active brake control systems of the vehicle are increasing. (Vehicle stability control, Panic brake assist ) We have developed a new hydraulic brake actuator for active brake control systems. New hydraulic brake actuator is composed of the three parts. (Hydraulic booster unit, Power supply unit, Control valve unit) This report describes the construction of the new hydraulic booster unit. 2 refs., 10 figs.

Coherent active polarization control without loss

Directory of Open Access Journals (Sweden)

Yuqian Ye

2017-11-01

Full Text Available We propose a lossless active polarization control mechanism utilizing an anisotropic dielectric medium with two coherent inputs. Using scattering matrix analysis, we derive analytically the required optical properties of the anisotropic medium that can behave as a switchable polarizing beam splitter. We also show that such a designed anisotropic medium can produce linearly polarized light at any azimuthal direction through coherent control of two inputs with a specific polarization state. Furthermore, we present a straightforward design-on-demand procedure of a subwavelength-thick metastructure that can possess the desired optical anisotropy at a flexible working wavelength. Our lossless coherent polarization control technique may lead to fast, broadband and integrated polarization control elements for applications in imaging, spectroscopy, and telecommunication.

Active Noise Control Experiments using Sound Energy Flu

Science.gov (United States)

Krause, Uli

2015-03-01

This paper reports on the latest results concerning the active noise control approach using net flow of acoustic energy. The test set-up consists of two loudspeakers simulating the engine noise and two smaller loudspeakers which belong to the active noise system. The system is completed by two acceleration sensors and one microphone per loudspeaker. The microphones are located in the near sound field of the loudspeakers. The control algorithm including the update equation of the feed-forward controller is introduced. Numerical simulations are performed with a comparison to a state of the art method minimising the radiated sound power. The proposed approach is experimentally validated.

Semi-active control of a cable-stayed bridge under multiple-support excitations.

Science.gov (United States)

Dai, Ze-Bing; Huang, Jin-Zhi; Wang, Hong-Xia

2004-03-01

This paper presents a semi-active strategy for seismic protection of a benchmark cable-stayed bridge with consideration of multiple-support excitations. In this control strategy, Magnetorheological (MR) dampers are proposed as control devices, a LQG-clipped-optimal control algorithm is employed. An active control strategy, shown in previous researches to perform well at controlling the benchmark bridge when uniform earthquake motion was assumed, is also used in this study to control this benchmark bridge with consideration of multiple-support excitations. The performance of active control system is compared to that of the presented semi-active control strategy. Because the MR fluid damper is a controllable energy- dissipation device that cannot add mechanical energy to the structural system, the proposed control strategy is fail-safe in that bounded-input, bounded-output stability of the controlled structure is guaranteed. The numerical results demonstrated that the performance of the presented control design is nearly the same as that of the active control system; and that the MR dampers can effectively be used to control seismically excited cable-stayed bridges with multiple-support excitations.

Active Control of Fan Noise: Feasibility Study. Volume 3; Active Fan Noise Cancellation in the NASA Lewis Active Noise Control Fan Facility

Science.gov (United States)

Pla, Frederic G.; Hu, Ziqiang; Sutliff, Daniel L.

1996-01-01

This report describes the Active Noise Cancellation (ANC) System designed by General Electric and tested in the NASA Lewis Research Center's (LERC) 48 inch Active Noise Control Fan (ANCF). The goal of this study is to assess the feasibility of using wall mounted secondary acoustic sources and sensors within the duct of a high bypass turbofan aircraft engine for global active noise cancellation of fan tones. The GE ANC system is based on a modal control approach. A known acoustic mode propagating in the fan duct is canceled using an array of flush-mounted compact sound sources. The canceling modal signal is generated by a modal controller. Inputs to the controller are signals from a shaft encoder and from a microphone array which senses the residual acoustic mode in the duct. The key results are that the (6,0) was completely eliminated at the 920 Hz design frequency and substantially reduced elsewhere. The total tone power was reduced 6.8 dB (out of a possible 9.8 dB). Farfield reductions of 15 dB (SPL) were obtained. The (4,0) and (4,1) modes were reduced simultaneously yielding a 15 dB PWL decrease. The results indicate that global attenuation of PWL at the target frequency was obtained in the aft quadrant using an ANC actuator and sensor system totally contained within the duct. The quality of the results depended on precise mode generation. High spillover into spurious modes generated by the ANC actuator array caused less than optimum levels of PWL reduction. The variation in spillover is believed to be due to calibration procedure, but must be confirmed in subsequent tests.

Fault tolerant control based on active fault diagnosis

DEFF Research Database (Denmark)

Niemann, Hans Henrik

2005-01-01

An active fault diagnosis (AFD) method will be considered in this paper in connection with a Fault Tolerant Control (FTC) architecture based on the YJBK parameterization of all stabilizing controllers. The architecture consists of a fault diagnosis (FD) part and a controller reconfiguration (CR......) part. The FTC architecture can be applied for additive faults, parametric faults, and for system structural changes. Only parametric faults will be considered in this paper. The main focus in this paper is on the use of the new approach of active fault diagnosis in connection with FTC. The active fault...... diagnosis approach is based on including an auxiliary input in the system. A fault signature matrix is introduced in connection with AFD, given as the transfer function from the auxiliary input to the residual output. This can be considered as a generalization of the passive fault diagnosis case, where...

A Novel Sliding Mode Control Technique for Indirect Current Controlled Active Power Filter

Directory of Open Access Journals (Sweden)

Juntao Fei

2012-01-01

Full Text Available A novel sliding mode control (SMC method for indirect current controlled three-phase parallel active power filter is presented in this paper. There are two designed closed loops in the system: one is the DC voltage controlling loop and the other is the reference current tracking loop. The first loop with a PI regulator is used to control the DC voltage approximating to the given voltage of capacitor, and the output of PI regulator through a low-pass filter is applied as the input of the power supply reference currents. The second loop implements the tracking of the reference currents using integral sliding mode controller, which can improve the harmonic treating performance. Compared with the direct current control technique, it is convenient to be implemented with digital signal processing system because of simpler system structure and better harmonic treating property. Simulation results verify that the generated reference currents have the same amplitude with the load currents, demonstrating the superior harmonic compensating effects with the proposed shunt active power filter compared with the hysteresis method.

Control Strategy of Active Power Filter Based on Modular Multilevel Converter

Science.gov (United States)

Xie, Xifeng

2018-03-01

To improve the capacity, pressure resistance and the equivalent switching frequency of active power filter (APF), a control strategy of APF based on Modular Multilevel Converter (MMC) is presented. In this Control Strategy, the indirect current control method is used to achieve active current and reactive current decoupling control; Voltage Balance Control Strategy is to stabilize sub-module capacitor voltage, the predictive current control method is used to Track and control of harmonic currents. As a result, the harmonic current is restrained, and power quality is improved. Finally, the simulation model of active power filter controller based on MMC is established in Matlab/Simulink, the simulation proves that the proposed strategy is feasible and correct.

Ethylphenidate as a selective dopaminergic agonist and methylphenidate-ethanol transesterification biomarker.

Science.gov (United States)

Patrick, Kennerly S; Corbin, Timothy R; Murphy, Cristina E

2014-12-01

We review the pharmaceutical science of ethylphenidate (EPH) in the contexts of drug discovery, drug interactions, biomarker for dl-methylphenidate (MPH)-ethanol exposure, potentiation of dl-MPH abuse liability, contemporary "designer drug," pertinence to the newer transdermal and chiral switch MPH formulations, as well as problematic internal standard. d-EPH selectively targets the dopamine transporter, whereas d-MPH exhibits equipotent actions at dopamine and norepinephrine transporters. This selectivity carries implications for the advancement of tailored attention-deficit/hyperactivity disorder (ADHD) pharmacotherapy in the era of genome-based diagnostics. Abuse of dl-MPH often involves ethanol coabuse. Carboxylesterase 1 enantioselectively transesterifies l-MPH with ethanol to yield l-EPH accompanied by significantly increased early exposure to d-MPH and rapid potentiation of euphoria. The pharmacokinetic component of this drug interaction can largely be avoided using dexmethylphenidate (dexMPH). This notwithstanding, maximal potentiated euphoria occurs following dexMPH-ethanol. C57BL/6 mice model dl-MPH-ethanol interactions: an otherwise depressive dose of ethanol synergistically increases dl-MPH stimulation; a substimulatory dose of dl-MPH potentiates a low, stimulatory dose of ethanol; ethanol elevates blood, brain, and urinary d-MPH concentrations while forming l-EPH. Integration of EPH preclinical neuropharmacology with clinical studies of MPH-ethanol interactions provides a translational approach toward advancement of ADHD personalized medicine and management of comorbid alcohol use disorder. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

Seismic active control by a heuristic-based algorithm

International Nuclear Information System (INIS)

Tang, Yu.

1996-01-01

A heuristic-based algorithm for seismic active control is generalized to permit consideration of the effects of control-structure interaction and actuator dynamics. Control force is computed at onetime step ahead before being applied to the structure. Therefore, the proposed control algorithm is free from the problem of time delay. A numerical example is presented to show the effectiveness of the proposed control algorithm. Also, two indices are introduced in the paper to assess the effectiveness and efficiency of control laws

A Decoupling Control Algorithm for Unwinding Tension System Based on Active Disturbance Rejection Control

Directory of Open Access Journals (Sweden)

Shanhui Liu

2013-01-01

Full Text Available This paper presents a new control methodology based on active disturbance rejection control (ADRC for designing the tension decoupling controller of the unwinding system in a gravure printing machine. The dynamic coupling can be actively estimated and compensated in real time, which makes feedback control an ideal approach to designing the decoupling controller of the unwinding system. This feature is unique to ADRC. In this study, a nonlinear mathematical model is established according to the working principle of the unwinding system. A decoupling model is also constructed to determine the order and decoupling plant of the unwinding system. Based on the order and decoupling plant, an ADRC decoupling control methodology is designed to enhance the tension stability in the unwinding system. The effectiveness and capability of the proposed methodology are verified through simulation and experiments. The results show that the proposed strategy not only realises a decoupling control for the unwinding system but also has an effective antidisturbance capability and is robust.

Variable Camber Continuous Aerodynamic Control Surfaces and Methods for Active Wing Shaping Control

Science.gov (United States)

Nguyen, Nhan T. (Inventor)

2016-01-01

An aerodynamic control apparatus for an air vehicle improves various aerodynamic performance metrics by employing multiple spanwise flap segments that jointly form a continuous or a piecewise continuous trailing edge to minimize drag induced by lift or vortices. At least one of the multiple spanwise flap segments includes a variable camber flap subsystem having multiple chordwise flap segments that may be independently actuated. Some embodiments also employ a continuous leading edge slat system that includes multiple spanwise slat segments, each of which has one or more chordwise slat segment. A method and an apparatus for implementing active control of a wing shape are also described and include the determination of desired lift distribution to determine the improved aerodynamic deflection of the wings. Flap deflections are determined and control signals are generated to actively control the wing shape to approximate the desired deflection.

Active and passive vibration control of structures

CERN Document Server

Spelsberg-Korspeter, Gottfried

2014-01-01

Active and Passive Vibration Control of Structures form an issue of very actual interest in many different fields of engineering, for example in the automotive and aerospace industry, in precision engineering (e.g. in large telescopes), and also in civil engineering. The papers in this volume bring together engineers of different background, and it fill gaps between structural mechanics, vibrations and modern control theory.  Also links between the different applications in structural control are shown.

BWR startup and shutdown activity transport control

Energy Technology Data Exchange (ETDEWEB)

Garcia, S.E., E-mail: sgarcia@epri.com [Electric Power Research Inst. (EPRI), Palo Alto, California (United States); Giannelli, J.F.; Jarvis, A.J., E-mail: jgiannelli@finetech.com, E-mail: ajarvis@finetech.com [Finetech, Inc., Parsippany, New Jersey (United States)

2010-07-01

This paper summarizes BWR industry experience on good practices for controlling the transport of corrosion product activity during shutdowns, particularly refueling outages, and for startup chemistry control to minimize IGSCC (intergranular stress corrosion cracking). For shutdown, overall goals are to minimize adverse impacts of crud bursts and the time required to remove activated corrosion products from the reactor coolant during the shutdown process prior to refueling, and to assist plants in predicting and controlling radiation exposure during outages. For startup, the overall goals are to highlight conditions during early heatup and startup when sources of reactor coolant oxidants are high, when there is a greater likelihood for chemical excursions associated with refueling outage work activities, and when hydrogen injection is not available to mitigate IGSCC due to system design limitations. BWR water chemistry has changed significantly in recent years with the adoption of hydrogen water chemistry, zinc addition and noble metal chemical applications. These processes have, in some instances, resulted in significant activity increases during shutdown evolutions, which together with reduced time for cleanup because of shorter outages, has consequently increased outage radiation exposure. A review several recent outages shows that adverse effects from these conditions can be minimized, leading to the set of good practice recommendations for shutdown chemistry control. Most plants lose the majority of their hydrogen availability hours during early startup because feedwater hydrogen injection systems were not originally designed to inject hydrogen below 20% power. Hydrogen availability has improved through modifications to inject hydrogen at lower power levels, some near 5%. However, data indicate that IGSCC is accelerated during early startup, when dissolved oxygen and hydrogen peroxide levels are high and reactor coolant temperatures are in the 300 to 400 {sup o

Swing Phase Control of Semi-Active Prosthetic Knee Using Neural Network Predictive Control With Particle Swarm Optimization.

Science.gov (United States)

Ekkachai, Kittipong; Nilkhamhang, Itthisek

2016-11-01

In recent years, intelligent prosthetic knees have been developed that enable amputees to walk as normally as possible when compared to healthy subjects. Although semi-active prosthetic knees utilizing magnetorheological (MR) dampers offer several advantages, they lack the ability to generate active force that is required during some states of a normal gait cycle. This prevents semi-active knees from achieving the same level of performance as active devices. In this work, a new control algorithm for a semi-active prosthetic knee during the swing phase is proposed to reduce this gap. The controller uses neural network predictive control and particle swarm optimization to calculate suitable command signals. Simulation results using a double pendulum model show that the generated knee trajectory of the proposed controller is more similar to the normal gait than previous open-loop controllers at various ambulation speeds. Moreover, the investigation shows that the algorithm can be calculated in real time by an embedded system, allowing for easy implementation on real prosthetic knees.

Baroreflex control of sympathetic activity in experimental hypertension

Directory of Open Access Journals (Sweden)

M.C.C. Irigoyen

1998-09-01

Full Text Available The arterial baroreceptor reflex system is one of the most powerful and rapidly acting mechanisms for controlling arterial pressure. The purpose of the present review is to discuss data relating sympathetic activity to the baroreflex control of arterial pressure in two different experimental models: neurogenic hypertension by sinoaortic denervation (SAD and high-renin hypertension by total aortic ligation between the renal arteries in the rat. SAD depresses baroreflex regulation of renal sympathetic activity in both the acute and chronic phases. However, increased sympathetic activity (100% was found only in the acute phase of sinoaortic denervation. In the chronic phase of SAD average discharge normalized but the pattern of discharges was different from that found in controls. High-renin hypertensive rats showed overactivity of the renin angiotensin system and a great depression of the baroreflexes, comparable to the depression observed in chronic sinoaortic denervated rats. However, there were no differences in the average tonic sympathetic activity or changes in the pattern of discharges in high-renin rats. We suggest that the difference in the pattern of discharges may contribute to the increase in arterial pressure lability observed in chronic sinoaortic denervated rats.

Indirect control of a single-phase active power filter

Directory of Open Access Journals (Sweden)

Mihai CULEA

2006-12-01

Full Text Available The control of shunt active power filters using PWM inverters consists in generating a reference by separating, using different methods, the harmonics to be eliminated. The methods used are time-consuming and need dedicated control and signal processing equipments. To avoid these setbacks a new method is proposed in the paper. The active power filter is a current PWM rectifier with voltage output and with a capacitor on the DC side. The PWM rectifier is controlled so that the sum of its current and the load’s current is a sinusoid. The control block as well as simulation results are presented.

Semi-active Control of Magneto-Rheological Dampers with Negative Stiffness

DEFF Research Database (Denmark)

Bhowmik, Subrata

2009-01-01

performance by introduction of apparent negative damper stiffness. The design of the control strategy aims at maximizing the damping ratio of the critical mode of the structure. Explicit solutions for the complex valued natural frequency of the damped structure and the associated damping ratio are obtained...... sufficiently accurate. This is done by letting the desired force be the input to an inverse Bingham model, which provides the corresponding desired voltage level of the MR damper. Numerical simulations are conducted to demonstrate the performance of the proposed semi-active control strategy with apparent......Effective damping of large and flexible structures by semi-active dampers relies greatly on the control strategy applied, which should combine the robustness of passive devices and the increased damping performance often available from active control. For structural control the Magneto...

Application of neural networks to seismic active control

International Nuclear Information System (INIS)

Tang, Yu.

1995-01-01

An exploratory study on seismic active control using an artificial neural network (ANN) is presented in which a singledegree-of-freedom (SDF) structural system is controlled by a trained neural network. A feed-forward neural network and the backpropagation training method are used in the study. In backpropagation training, the learning rate is determined by ensuring the decrease of the error function at each training cycle. The training patterns for the neural net are generated randomly. Then, the trained ANN is used to compute the control force according to the control algorithm. The control strategy proposed herein is to apply the control force at every time step to destroy the build-up of the system response. The ground motions considered in the simulations are the N21E and N69W components of the Lake Hughes No. 12 record that occurred in the San Fernando Valley in California on February 9, 1971. Significant reduction of the structural response by one order of magnitude is observed. Also, it is shown that the proposed control strategy has the ability to reduce the peak that occurs during the first few cycles of the time history. These promising results assert the potential of applying ANNs to active structural control under seismic loads

Development of magnetostrictive active members for control of space structures

Science.gov (United States)

Johnson, Bruce G.; Avakian, Kevin M.; Fenn, Ralph C.; Gaffney, Monique S.; Gerver, Michael J.; Hawkey, Timothy J.; Boudreau, Donald J.

1992-08-01

The goal of this Phase 2 Small Business Innovative Research (SBIR) project was to determine the technical feasibility of developing magnetostrictive active members for use as truss elements in space structures. Active members control elastic vibrations of truss-based space structures and integrate the functions of truss structure element, actively controlled actuator, and sensor. The active members must control structural motion to the sub-micron level and, for many proposed space applications, work at cryogenic temperatures. Under this program both room temperature and cryogenic temperature magnetostrictive active members were designed, fabricated, and tested. The results of these performance tests indicated that room temperature magnetostrictive actuators feature higher strain, stiffness, and force capability with lower amplifier requirements than similarly sized piezoelectric or electrostrictive active members, at the cost of higher mass. Two different cryogenic temperature magnetostrictive materials were tested at liquid nitrogen temperatures, both with larger strain capability than the room temperature magnetostrictive materials. The cryogenic active member development included the design and fabrication of a cryostat that allows operation of the cryogenic active member in a space structure testbed.

Repetitive grooming and sensorimotor abnormalities in an ephrin-A knockout model for Autism Spectrum Disorders.

Science.gov (United States)

Wurzman, Rachel; Forcelli, Patrick A; Griffey, Christopher J; Kromer, Lawrence F

2015-02-01

EphA receptors and ephrin-A ligands play important roles in neural development and synaptic plasticity in brain regions where expression persists into adulthood. Recently, EPHA3 and EPHA7 gene mutations were linked with Autism Spectrum Disorders (ASDs) and developmental neurological delays, respectively. Furthermore, deletions of ephrin-A2 or ephrin-A3, which exhibit high binding affinity for EphA3 and EphA7 receptors, are associated with subtle deficits in learning and memory behavior and abnormalities in dendritic spine morphology in the cortex and hippocampus in mice. To better characterize a potential role for these ligands in ASDs, we performed a comprehensive behavioral characterization of anxiety-like, sensorimotor, learning, and social behaviors in ephrin-A2/-A3 double knockout (DKO) mice. The predominant phenotype in DKO mice was repetitive and self-injurious grooming behaviors such as have been associated with corticostriatal circuit abnormalities in other rodent models of neuropsychiatric disorders. Consistent with ASDs specifically, DKO mice exhibited decreased preference for social interaction in the social approach assay, decreased locomotor activity in the open field, increased prepulse inhibition of acoustic startle, and a shift towards self-directed activity (e.g., grooming) in novel environments, such as marble burying. Although there were no gross deficits in cognitive assays, subtle differences in performance on fear conditioning and in the Morris water maze resembled traits observed in other rodent models of ASD. We therefore conclude that ephrin-A2/-A3 DKO mice have utility as a novel ASD model with an emphasis on sensory abnormalities and restricted, repetitive behavioral symptoms. Copyright © 2014 Elsevier B.V. All rights reserved.

Active Control of Contact Force for a Pantograph-Catenary System

Directory of Open Access Journals (Sweden)

Jiqiang Wang

2016-01-01

Full Text Available The performance of the high speed trains depends critically on the quality of the contact in the pantograph-catenary interaction. Maintaining a constant contact force needs taking special measures and one of the methods is to utilize active control to optimize the contact force. A number of active control methods have been proposed in the past decade. However, the primary objective of these methods has been to reduce the variation of the contact force in the pantograph-catenary system, ignoring the effects of locomotive vibrations on pantograph-catenary dynamics. Motivated by the problems in active control of vibration in large scale structures, the author has developed a geometric framework specifically targeting the remote vibration suppression problem based only on local control action. It is the intention of the paper to demonstrate its potential in the active control of the pantograph-catenary interaction, aiming to minimize the variation of the contact force while simultaneously suppressing the vibration disturbance from the train. A numerical study is provided through the application to a simplified pantograph-catenary model.

"Active Flux" DTFC-SVM Sensorless Control of IPMSM

DEFF Research Database (Denmark)

Boldea, Ion; Codruta Paicu, Mihaela; Gheorghe-Daniel, Andreescu,

2009-01-01

This paper proposes an implementation of a motionsensorless control system in wide speed range based on "active flux" observer, and direct torque and flux control with space vector modulation (DTFC-SVM) for the interior permanent magnet synchronous motor (IPMSM), without signal injection....... The concept of "active flux" (or "torque producing flux") turns all the rotor salient-pole ac machines into fully nonsalient-pole ones. A new function for Lq inductance depending on torque is introduced to model the magnetic saturation. Notable simplification in the rotor position and speed estimation...

Controlling and tracking hyperchaotic Roessler system via active backstepping design

International Nuclear Information System (INIS)

Zhang Hao; Ma Xikui; Li Ming; Zou Jianlong

2005-01-01

This paper presents a novel active backstepping control approach for controlling hyperchaotic Roessler system to a steady state as well as tracking of any desire trajectory to be achieved in a systematic way. The proposed method is a systematic design approach and consists in a recursive procedure that interlaces the choice of a Lyapunov function with the design of active control. Numerical results show that the controller is singularity free and the closed-loop system is stable globally. Especially, the main feature of this technique is that it gives the flexibility to construct a control law. Finally, numerical experiments verify the feasibility and effectiveness of the proposed control technique

Feedback Linearization Control of a Shunt Active Power Filter Using a Fuzzy Controller

Directory of Open Access Journals (Sweden)

Tianhua Li

2013-09-01

Full Text Available In this paper, a novel feedback linearization based sliding mode controlled parallel active power filter using a fuzzy controller is presented in a three-phase three-wire grid. A feedback linearization control with fuzzy parameter self-tuning is used to implement the DC side voltage regulation while a novel integral sliding mode controller is applied to reduce the total harmonic distortion of the supply current. Since traditional unit synchronous sinusoidal signal calculation methods are not applicable when the supply voltage contains harmonics, a novel unit synchronous sinusoidal signal computing method based on synchronous frame transforming theory is presented to overcome this disadvantage. The simulation results verify that the DC side voltage is very stable for the given value and responds quickly to the external disturbance. A comparison is also made to show the advantages of the novel unit sinusoidal signal calculating method and the super harmonic treatment property of the designed active power filter.

Nitrate control strategies in an activated sludge wastewater treatment process

Energy Technology Data Exchange (ETDEWEB)

Shen, Wenhao; Tao, Erpan; Chen, Xiaoquan; Liu, Dawei [South China University of Technology, Guangzhou (China); Liu, Hongbin [Kyung Hee University, Yongin (Korea, Republic of)

2014-03-15

We studied nitrate control strategies in an activated sludge wastewater treatment process (WWTP) based on the activated sludge model. Two control strategies, back propagation for proportional-integral-derivative (BP-PID) and adaptive-network based fuzzy inference systems (ANFIS), are applied in the WWTP. The simulation results show that the simple local constant setpoint control has poor control effects on the nitrate concentration control. However, the ANFIS (4*1) controller, which considers not only the local constant setpoint control of the nitrate concentration, but also three important indices in the effluent--ammonia concentration, total suspended sludge concentration and total nitrogen concentration--demonstrates good control performance. The results also prove that ANFIS (4*1) controller has better control performance than that of the controllers PI, BP-PID and ANFIS (2*1), and that the ANFIS (4*1) controller is effective in improving the effluent quality and maintaining the stability of the effluent quality.

Temperature-gated thermal rectifier for active heat flow control.

Science.gov (United States)

Zhu, Jia; Hippalgaonkar, Kedar; Shen, Sheng; Wang, Kevin; Abate, Yohannes; Lee, Sangwook; Wu, Junqiao; Yin, Xiaobo; Majumdar, Arun; Zhang, Xiang

2014-08-13

Active heat flow control is essential for broad applications of heating, cooling, and energy conversion. Like electronic devices developed for the control of electric power, it is very desirable to develop advanced all-thermal solid-state devices that actively control heat flow without consuming other forms of energy. Here we demonstrate temperature-gated thermal rectification using vanadium dioxide beams in which the environmental temperature actively modulates asymmetric heat flow. In this three terminal device, there are two switchable states, which can be regulated by global heating. In the "Rectifier" state, we observe up to 28% thermal rectification. In the "Resistor" state, the thermal rectification is significantly suppressed (Rectifier state. This temperature-gated rectifier can have substantial implications ranging from autonomous thermal management of heating and cooling systems to efficient thermal energy conversion and storage.

Active and passive control of zinc phthalocyanine photodynamics

NARCIS (Netherlands)

Sharma, Divya; Huijser, Jannetje Maria; Savolainen, Janne; Steen, Gerrit Willem; Herek, Jennifer Lynn

2013-01-01

In this work we report on the ultrafast photodynamics of the photosensitizer zinc phthalocyanine (ZnPc) and manipulation thereof. Two approaches are followed: active control via pulse shaping and passive control via strategic manipulation in the periphery of the molecular structure. The objective of

Re-Active Passive devices for control of noise transmission through a panel

Science.gov (United States)

Carneal, James P.; Giovanardi, Marco; Fuller, Chris R.; Palumbo, Dan

2008-01-01

Re-Active Passive devices have been developed to control low-frequency (transmission through a panel. These devices use a combination of active, re-active, and passive technologies packaged into a single unit to control a broad frequency range utilizing the strength of each technology over its best suited frequency range. The Re-Active Passive device uses passive constrained layer damping to cover relatively high-frequency range (>150 Hz), reactive distributed vibration absorber to cover the medium-frequency range (50-200 Hz), and active control for controlling low frequencies (transmission through a panel mounted in the Transmission Loss Test Facility at Virginia Tech. Experimental results are presented for the bare panel, and combinations of passive treatment, reactive treatment, and active control. Results indicate that three Re-Active Passive devices were able to increase the overall broadband (15-1000 Hz) transmission loss by 9.4 dB. These three devices added a total of 285 g to the panel mass of 6.0 kg, or approximately 5%, not including control electronics.

Control of high frequency microactuators using active structures

International Nuclear Information System (INIS)

Kreth, P A; Alvi, F S; Reese, B M; Oates, W S

2015-01-01

A fluidically driven microactuator that generates supersonic, pulsed microjets has been implemented with smart materials to actively and precisely control the frequency of the microjets in a closed-loop manner. Since this actuator relies on a number of microscale flow and acoustic phenomena to produce the pulsed microjets, its resonant frequency is determined by its geometry and other flow parameters. The design discussed in this paper integrates piezoelectric stacks by connecting them to movable sidewalls within the actuator such that the microactuator's internal geometry can be controlled by varying the voltage across the piezo-stacks. An open-loop control scheme demonstrates the frequency modulation capabilities that are enabled with this design: very large frequency deviations (up to ±500 Hz) around the actuator design frequency are attained at very high rates (up to 1 kHz). Closed-loop control of the microactuator's frequency was also demonstrated, and the results indicate that (combined with appropriate sensors) this actuator could be used effectively for active, feedback control in high-speed, resonance-dominated flowfields. This proof of concept study clearly illustrates the ability of this robust and compact actuator to produce perturbations that can be modulated and controlled based on the desired control objective. (paper)

Active control of noise radiation from vibrating structures

DEFF Research Database (Denmark)

Mørkholt, Jakob

developed, based on the theory of radiation filters for estimating the sound radiation from multimodal vibrations. This model has then been used in simulations of optimal feedback control, with special emphasis of the stability margins of the optimal control scheme. Two different methods of designing...... optimal and robust discrete-time feedback controllers for active vibration control of multimodal structures have been compared. They have been showed to yield controllers with identical frequency response characteristics, even though they employ completely different methods of numerical solutions...... and result in different representations of the controllers. The Internal Model Control structure combined with optimal filtering is suggested as an alternative to state space optimal control techniques for designing robust optimal controllers for audio frequency vibration control of resonant structures....

Preemptive hemodynamic intervention restricting the administration of fluids attenuates lung edema progression in oleic acid-induced lung injury.

Science.gov (United States)

Gil Cano, A; Gracia Romero, M; Monge García, M I; Guijo González, P; Ruiz Campos, J

2017-04-01

A study is made of the influence of preemptive hemodynamic intervention restricting fluid administration upon the development of oleic acid-induced lung injury. A randomized in vivo study in rabbits was carried out. University research laboratory. Sixteen anesthetized, mechanically ventilated rabbits. Hemodynamic measurements obtained by transesophageal Doppler signal. Respiratory mechanics computed by a least square fitting method. Lung edema assessed by the ratio of wet weight to dry weight of the right lung. Histological examination of the left lung. Animals were randomly assigned to either the early protective lung strategy (EPLS) (n=8) or the early protective hemodynamic strategy (EPHS) (n=8). In both groups, lung injury was induced by the intravenous infusion of oleic acid (OA) (0.133mlkg -1 h -1 for 2h). At the same time, the EPLS group received 15mlkg -1 h -1 of Ringer lactate solution, while the EPHS group received 30mlkg -1 h -1 . Measurements were obtained at baseline and 1 and 2h after starting OA infusion. After 2h, the cardiac index decreased in the EPLS group (p<0.05), whereas in the EPHS group it remained unchanged. Lung compliance decreased significantly only in the EPHS group (p<0.05). Lung edema was greater in the EPHS group (p<0.05). Histological damage proved similar in both groups (p=0.4). In this experimental model of early lung injury, lung edema progression was attenuated by preemptively restricting the administration of fluids. Copyright © 2016 Elsevier España, S.L.U. y SEMICYUC. All rights reserved.

Applications of adaptive filters in active noise control

Science.gov (United States)

Darlington, Paul

The active reduction of acoustic noise is achieved by the addition of a cancelling acoustic signal to the unwanted sound. Successful definition of the cancelling signal amounts to a system identification problem. Recent advances in adaptive signal processing have allowed this problem to be tackled using adaptive filters, which offer significant advantages over conventional solutions. The extension of adaptive noise cancelling techniques, which were developed in the electrical signal conditioning context, to the control of acoustic systems is studied. An analysis is presented of the behavior of the Widrow-Hoff LMS adaptive noise canceller with a linear filter in its control loop. The active control of plane waves propagating axially in a hardwalled duct is used as a motivating model problem. The model problem also motivates the study of the effects of feedback around an LMS adaptive filter. An alternative stochastic gradient algorithm for controlling adaptive filters in the presence of feedback is presented.

Development of Active Noise Control System for Quieting Transformer Noise

Energy Technology Data Exchange (ETDEWEB)

Lee, Bok Kyu; Song, Seik Young; Choi, Huo Yul [Korea Electric Power Research Institute, Taejon (Korea, Republic of); Yun, Dae Hea; Lee, Hyuk Jae [Korea Electrotechnology Research Institute, Changwon (Korea, Republic of)

1997-12-31

The passive noise control technique made use of sound-absorbing or soundproofing materials, so it required a large area and high cost for installation and had a drawback of poor performance at low frequency. Compared to this, the Active Noise Control attenuates noise sound pressure by using secondary source which has same performance ay low-frequency. Furthermore, it is able to save space and expenses. - research on adaptive algorithms - evaluation of global attenuation of the control - computer simulation - real-time Active Noise Control System Hardware Implementation - ANC system setting in the noisy area.

Bi-Level Decentralized Active Power Control for Large-Scale Wind Farm Cluster

DEFF Research Database (Denmark)

Huang, Shengli; Wu, Qiuwei; Guo, Yifei

2018-01-01

This paper presents a bi-level decentralized active power control (DAPC) for a large-scale wind farm cluster, consisting of several wind farms for better active power dispatch. In the upper level, a distributed active power control scheme based on the distributed consensus is designed to achieve...... fair active power sharing among multiple wind farms, which generates the power reference for each wind farm. A distributed estimator is used to estimate the total available power of all wind farms. In the lower level, a centralized control scheme based on the Model Predictive Control (MPC) is proposed...... to regulate active power outputs of all wind turbines (WTs) within a wind farm, which reduces the fatigue loads of WTs while tracking the power reference obtained from the upper level control. A wind farm cluster with 8 wind farms and totally 160 WTs, was used to test the control performance of the proposed...

Predictor effect of Locus Of Control (LOC) on self-care activities and metabolic control in individuals with type 2 diabetes.

Science.gov (United States)

Büyükkaya Besen, Dilek; Günüşen, Neslihan; Arda Sürücü, Hamdiye; Koşar, Cansu

2016-01-01

Previous studies have examined the role of individuals' personal characteristics in diabetes management and used the locus of control theory to assess adherence to a diabetes management regimen. These studies have emphasized that having internal locus of control may be a protective factor in diabetes management. The purpose of this study is to determine the predictor effect of locus of control on self-care activities and A1c level. The study is descriptive and relational. Researchers used a Diabetes Self-Care Activities Scale and a Locus of Control Scale to collect data. The study sample consisted of 129 individuals with type 2 diabetes. The average score of locus of control of individuals with diabetes was 10.26, and the frequency of self-care activities in the past week was 2.9 days. A weak but statistically significant negative relation was found between the locus of control level and self-care activities of individuals with diabetes, which had no effect on A1c. It was determined that locus of control predicts 19% of self-care activities. According to the study results, having internal locus of control had positive effects on self-care activities. Training and planning activities to improve internal locus of control can improve diabetes management.

Characterization of an Actively Controlled Three-Dimensional Turret Wake

Science.gov (United States)

Shea, Patrick; Glauser, Mark

2012-11-01

Three-dimensional turrets are commonly used for housing optical systems on airborne platforms. As bluff bodies, these geometries generate highly turbulent wakes that decrease the performance of the optical systems and the aircraft. The current experimental study looked to use dynamic suction in both open and closed-loop control configurations to actively control the turret wake. The flow field was characterized using dynamic pressure and stereoscopic PIV measurements in the wake of the turret. Results showed that the suction system was able to manipulate the wake region of the turret and could alter not only the spatial structure of the wake, but also the temporal behavior of the wake flow field. Closed-loop, feedback control techniques were used to determine a more optimal control input for the flow control. Similar control effects were seen for both the steady open-loop control case and the closed-loop feedback control configuration with a 45% reduction in the suction levels when comparing the closed-loop to the open-loop case. These results provide unique information regarding the development of the baseline three-dimensional wake and the wake with three different active flow control configurations.

Interaction between functional health literacy, patient activation, and glycemic control

Directory of Open Access Journals (Sweden)

Woodard LD

2014-07-01

Full Text Available LeChauncy D Woodard, Cassie R Landrum, Amber B Amspoker, David Ramsey, Aanand D Naik Veterans Affairs Health Services Research and Development Center for Innovations in Quality, Effectiveness and Safety, Michael E DeBakey Veterans Affairs Medical Center, and Section of Health Services Research, Department of Medicine, Baylor College of Medicine, Houston, TX, USA Background: Functional health literacy (FHL and patient activation can impact diabetes control through enhanced diabetes self-management. Less is known about the combined effect of these characteristics on diabetes outcomes. Using brief, validated measures, we examined the interaction between FHL and patient activation in predicting glycosylated hemoglobin (HbA1c control among a cohort of multimorbid diabetic patients.Methods: We administered a survey via mail to 387 diabetic patients with coexisting ­hypertension and ischemic heart disease who received outpatient care at one regional VA medical center between November 2010 and December 2010. We identified patients with the study conditions using the International Classification of Diseases-Ninth Revision-Clinical ­Modification (ICD-9-CM diagnoses codes and Current Procedure Terminology (CPT ­procedures codes. Surveys were returned by 195 (50.4% patients. We determined patient activation levels based on participant responses to the 13-item Patient Activation Measure and FHL levels using the single-item screening question, “How confident are you filling out medical forms by yourself?” We reviewed patient medical records to assess glycemic control. We used multiple logistic regression to examine whether activation and FHL were individually or jointly related to HbA1c control.Results: Neither patient activation nor FHL was independently related to glycemic control in the unadjusted main effects model; however, the interaction between the two was significantly associated with glycemic control (odds ratio 1.05 [95% confidence

Active control of multi-input hydraulic journal bearing system

Science.gov (United States)

Chuang, Jen-Chen; Chen, Chi-Yin; Tu, Jia-Ying

2016-09-01

Because of the advantages of high accuracy, high capacity, and low friction, the development of hydrostatic bearing for machine tool receives significant attention in the last decades. The mechanics and mechanical design of hydrostatic journal bearing with capillary restrictors has been discussed in literature. However, pragmatically, the undesired loading effects of cutting force tend to result in resonance and instability of the rotor and damage the shaft during operation. Therefore, multi-input, active flow control using state feedback design is proposed in this paper. To this purpose, the proportional pressure valves are added to the hydraulic system as active control devices, and the linearised models of the bearing and valve are discussed and identified. Simulation and experimental work is conducted to verify the proposed active control and parameter identification techniques. The results show that the unbalance responses of the rotor are reduced by the proposed state feedback controller, which is able to regulate the flow pressure effectively, thus enhancing the stability and accuracy of the hydraulic journal bearing.

Comparison of backstepping and modified active control in ...

Indian Academy of Sciences (India)

In this article, projective synchronization of double–scroll attractor of an extended Bonöffer–van der Pol oscillator (BVPO) is considered via the backstepping and active control techniques. In each synchronization scheme, a single control function is designed to achieve projective synchronization between two Bonhöffer–van ...

Reserve-building activities in multiple sclerosis patients and healthy controls: a descriptive study.

Science.gov (United States)

Schwartz, Carolyn E; Ayandeh, Armon; Ramanathan, Murali; Benedict, Ralph; Dwyer, Michael G; Weinstock-Guttman, Bianca; Zivadinov, Robert

2015-08-12

Cognitive reserve has been implicated as a possible protective factor in multiple sclerosis (MS) but to date no study has compared reserve-building activities across disease course or to healthy controls. This study aims to describe differences in reserve-building activities across the MS disease course and healthy controls. Secondary analysis of a cross-sectional cohort study that included 276 healthy controls, and subjects with clinically isolated syndrome (CIS; n = 67), relapsing-remitting MS (RRMS; n = 358) and secondary progressive MS (PMS; n = 109). Past reserve-building activities were operationalized as occupational attainment and education. Current activities comprised 6 strenuous and 6 non-strenuous activities, including 5 reserve-building activities and television-watching. Multivariate Analysis of Variance models examined group differences in past and current activities, after adjusting for covariates. There were group differences in past and current reserve-building activities. SPMS patients had lower past reserve-building activities than healthy controls. All forms of MS engaged in fewer strenuous current reserve-building pursuits than healthy controls. RRMS read less than healthy controls. SPMS engaged in fewer job-related non-strenuous activities. All MS groups watched more television than healthy controls. MS patients show significantly fewer past and present reserve-building activities. Although it is difficult to establish causality without future prospective studies, lifestyle-modifying interventions should prioritize expanding MS patients' repertoire of strenuous and non-strenuous activities.

Controlled Fab installation onto polymeric micelle nanoparticles for tuned bioactivity

Science.gov (United States)

Chen, Shaoyi; Florinas, Stelios; Teitgen, Abigail; Xu, Ze-Qi; Gao, Changshou; Wu, Herren; Kataoka, Kazunori; Cabral, Horacio; Christie, R. James

2017-12-01

Antibodies and antigen-binding fragments (Fabs) can be used to modify the surface of nanoparticles for enhanced target binding. In our previous work, site-specific conjugation of Fabs to polymeric micelles using conventional methods was limited to approximately 30% efficiency, possibly due to steric hindrance related to macromolecular reactants. Here, we report a new method that enables conjugation of Fabs onto a micelle surface in a controlled manner with up to quantitative conversion of nanoparticle reactive groups. Variation of (i) PEG spacer length in a heterofunctionalized cross-linker and (ii) Fab/polymer feed ratios resulted in production of nanoparticles with a range of Fab densities on the surface up to the theoretical maximum value. The biological impact of variable Fab density was evaluated in vitro with respect to cell uptake and cytotoxicity of a drug-loaded (SN38) targeted polymeric micelle bearing anti-EphA2 Fabs. Fab conjugation increased cell uptake and potency compared with non-targeted micelles, although a Fab density of 60% resulted in decreased uptake and potency of the targeted micelles. Altogether, our findings demonstrate that conjugation strategies can be optimized to allow control of Fab density on the surface of nanoparticles and also that Fab density may need to be optimized for a given cell-surface target to achieve the highest bioactivity.

Improved Load Frequency Control Using a Fast Acting Active Disturbance Rejection Controller

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Md Mijanur Rahman

2017-10-01

Full Text Available System frequency may change from defined values while transmitting power from one area to another in an interconnected power system due to various reasons such as load changes and faults. This frequency change causes a frequency error in the system. However, the system frequency should always be maintained close to the nominal value even in the presence of model uncertainties and physical constraints. This paper proposes an Active Disturbance Rejection Controller (ADRC-based load frequency control (LFC of an interconnected power system. The controller incorporates effects of generator inertia and generator electrical proximity to the point of disturbances. The proposed controller reduces the magnitude error of the area control error (ACE of an interconnected power system compared to the standard controller. The simulation results verify the effectiveness of proposed ADRC in the application of LFC of an interconnected power system.

Active Engine Mounting Control Algorithm Using Neural Network

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Fadly Jashi Darsivan

2009-01-01

Full Text Available This paper proposes the application of neural network as a controller to isolate engine vibration in an active engine mounting system. It has been shown that the NARMA-L2 neurocontroller has the ability to reject disturbances from a plant. The disturbance is assumed to be both impulse and sinusoidal disturbances that are induced by the engine. The performance of the neural network controller is compared with conventional PD and PID controllers tuned using Ziegler-Nichols. From the result simulated the neural network controller has shown better ability to isolate the engine vibration than the conventional controllers.

Active surge control for variable speed axial compressors.

Science.gov (United States)

Lin, Shu; Yang, Chunjie; Wu, Ping; Song, Zhihuan

2014-09-01

This paper discusses active surge control in variable speed axial compressors. A compression system equipped with a variable area throttle is investigated. Based on a given compressor model, a fuzzy logic controller is designed for surge control and a proportional speed controller is used for speed control. The fuzzy controller uses measurements of the change of pressure rise as well as the change of mass flow to determine the throttle opening. The presented approach does not require the knowledge of system equilibrium or the surge line. Numerical simulations show promising results. The proposed fuzzy logic controller performs better than a backstepping controller and is capable to suppress surge at different operating points. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Active Complementary Control for Affine Nonlinear Control Systems With Actuator Faults.

Science.gov (United States)

Fan, Quan-Yong; Yang, Guang-Hong

2017-11-01

This paper is concerned with the problem of active complementary control design for affine nonlinear control systems with actuator faults. The outage and loss of effectiveness fault cases are considered. In order to achieve the performance enhancement of the faulty control system, the complementary control scheme is designed in two steps. Firstly, a novel fault estimation scheme is developed. Then, by using the fault estimations to reconstruct the faulty system dynamics and introducing a cost function as the optimization objective, a nearly optimal complementary control is obtained online based on the adaptive dynamic programming (ADP) method. Unlike most of the previous ADP methods with the addition of a probing signal, new adaptive weight update laws are derived to guarantee the convergence of neural network weights and the stability of the closed-loop system, which strongly supports the online implementation of the ADP method. Finally, two simulation examples are given to illustrate the performance and effectiveness of the proposed method.

Should Ecosystem Management Involve Active Control of Species Abundances?

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Robert B. Lessard

2005-12-01

Full Text Available We review four case studies in which there is a risk of extinction or severe reduction in highly valued species if we ignore either, or both, of two ecosystem control options. "Symptomatic control" implies direct control of extinction risk through direct harvesting or culling of competitors and predators. "Systemic control" implies treating the causes of the problem that led to an unnaturally high abundance in the first place. We demonstrate, with a discussion of historically observed population trends, how surprising trophic interactions can emerge as a result of alterations to a system. Simulation models were developed for two of the case studies as aids to adaptive policy design, to expose possible abundance changes caused by trophic interactions and to highlight key uncertainties about possible responses to ecosystem management policies involving active intervention to control abundances. With reasonable parameter values, these models predict a wide range of possible responses given available data, but do indicate a good chance that active control would reverse declines and reverse extinction risks. We find that controlling seal (Phoca vitulina populations in the Georgia Strait increases juvenile survival rates of commercial salmon (Oncorhynchus spp. species, but that commensurate increases in hake populations from decreased seal predation could be a compensatory source of predation on juvenile salmon. We also show that wolf (Canis lupus control and moose (Alces alces harvest bring about a recovery in caribou (Rangifer tarandus caribou populations, where simple habitat protection policies fail to recover caribou before wolf predation causes severe declines. The results help address a common problem in disturbed ecosystems, where controlling extinction risks can mean choosing between active control of species abundance or establishing policies of protection, and allowing threatened species to recover naturally.

Activity monitor intervention to promote physical activity of physicians-in-training: randomized controlled trial.

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Anne N Thorndike

Full Text Available Physicians are expected to serve as role models for healthy lifestyles, but long work hours reduce time for healthy behaviors. A hospital-based physical activity intervention could improve physician health and increase counseling about exercise.We conducted a two-phase intervention among 104 medical residents at a large hospital in Boston, Massachusetts. Phase 1 was a 6-week randomized controlled trial comparing daily steps of residents assigned to an activity monitor displaying feedback about steps and energy consumed (intervention or to a blinded monitor (control. Phase 2 immediately followed and was a 6-week non-randomized team steps competition in which all participants wore monitors with feedback. Phase 1 outcomes were: 1 median steps/day and 2 proportion of days activity monitor worn. The Phase 2 outcome was mean steps/day on days monitor worn (≥500 steps/day. Physiologic measurements were collected at baseline and study end. Median steps/day were compared using Wilcoxon rank-sum tests. Mean steps were compared using repeated measures regression analyses.In Phase 1, intervention and control groups had similar activity (6369 vs. 6063 steps/day, p = 0.16 and compliance with wearing the monitor (77% vs. 77% of days, p = 0.73. In Phase 2 (team competition, residents recorded more steps/day than during Phase 1 (CONTROL: 7,971 vs. 7,567, p = 0.002;7,832 vs. 7,739, p = 0.13. Mean compliance with wearing the activity monitor decreased for both groups during Phase 2 compared to Phase 1 (60% vs. 77%, p<0.001. Mean systolic blood pressure decreased (p = 0.004 and HDL cholesterol increased (p<0.001 among all participants at end of study compared to baseline.Although the activity monitor intervention did not have a major impact on activity or health, the high participation rates of busy residents and modest changes in steps, blood pressure, and HDL suggest that more intensive hospital-based wellness programs have potential for

Force Feedback Control Method of Active Tuned Mass Damper

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Xiuli Wang

2017-01-01

Full Text Available Active tuned mass dampers as vibration-control devices are widely used in many fields for their good stability and effectiveness. To improve the performance of such dampers, a control method based on force feedback is proposed. The method offers several advantages such as high-precision control and low-performance requirements for the actuator, as well as not needing additional compensators. The force feedback control strategy was designed based on direct-velocity feedback. The effectiveness of the method was verified in a single-degree-of-freedom system, and factors such as damping effect, required active force, actuator stroke, and power consumption of the damper were analyzed. Finally, a simulation study was performed by configuring a main complex elastic-vibration-damping system. The results show that the method provides effective control over modal resonances of multiple orders of the system and improves its dynamics performance.

Microsomal prostaglandin E synthase-1, ephrins, and ephrin kinases as suspected therapeutic targets in arthritis: exposed by "criminal profiling".

Science.gov (United States)

Romanovsky, Andrej A; Ivanov, Andrei I; Petersen, Scott R

2006-06-01

Feeding information obtained in one criminal case into the profile of another crime often helps to solve the latter. The literature on two different "crimes," namely, acute systemic inflammation and arthritis (including osteoarthritis [OA] and rheumatoid arthritis [RA] deals largely with the same "gang" of inflammatory mediators, such as prostaglandin (PG) E2. Early investigations suggested that microsomal PGE synthase-1 (mPGES-1; a terminal PGE2-synthesizing enzyme) plays a pivotal role in bacterial lipopolysaccharide (LPS)-induced systemic inflammation, but overlooked the possibility that the same enzyme could be involved in OA or RA. Later studies showed that mPGES-1 is indeed a key perpetrator in arthritic diseases, a fact that could have been predicted earlier by pooling the new knowledge about mPGES-1 into the profile of arthritic diseases. In this review, we analyze our recent study on the expression of erythropoietin-producing hepatocellular (Eph) receptor kinases and their ligands, ephrins, in LPS-induced systemic inflammation. By pooling these results together with literature data into the profile of RA, we conclude that Eph kinases and ephrins are prime suspects for being involved in the pathogenesis of RA. We further conjecture that the involvement of Eph kinases and ephrins may be realized via the induction of angiogenesis in the inflamed joint, promotion of leukocyte infiltration, and activation of the infiltrated cells. Studies to test this new hypothesis seem warranted, and our prediction is that the "smoking gun" will be found.

Resource Leveling Based on Backward Controlling Activity in Line of Balance

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Lihui Zhang

2017-01-01

Full Text Available The line of balance method that provides continuous and uninterrupted use of resources is one of the best methods for repetitive project resource management. This paper develops a resource leveling algorithm based on the backward controlling activity in line of balance. The backward controlling activity is a kind of special activity, and if its duration is prolonged the project duration could be reduced. It brings two advantages to the resource leveling: both the resource allocated on the backward activity and the project duration are reduced. A resource leveling algorithm is presented which permits the number of crews of the backward controlling activity to be reduced until the terminal situation is reached, where the backward controlling activity does not exist or the number of crews cannot be reduced. That adjustment enables the productivity of all activities to be consistent. An illustrative pipeline project demonstrates the improvement in resource leveling. And this study designed a MATLAB program to execute the design algorithm. The proposed model could help practitioners to achieve the goals of both resource leveling and project duration reduction without increasing any resource.

Predictor effect of Locus Of Control (LOC on self-care activities and metabolic control in individuals with type 2 diabetes

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Dilek Büyükkaya Besen

2016-11-01

Full Text Available Background Previous studies have examined the role of individuals’ personal characteristics in diabetes management and used the locus of control theory to assess adherence to a diabetes management regimen. These studies have emphasized that having internal locus of control may be a protective factor in diabetes management. Objective The purpose of this study is to determine the predictor effect of locus of control on self-care activities and A1c level. Method The study is descriptive and relational. Researchers used a Diabetes Self-Care Activities Scale and a Locus of Control Scale to collect data. The study sample consisted of 129 individuals with type 2 diabetes. Results The average score of locus of control of individuals with diabetes was 10.26, and the frequency of self-care activities in the past week was 2.9 days. A weak but statistically significant negative relation was found between the locus of control level and self-care activities of individuals with diabetes, which had no effect on A1c. It was determined that locus of control predicts 19% of self-care activities. Conclusion According to the study results, having internal locus of control had positive effects on self-care activities. Training and planning activities to improve internal locus of control can improve diabetes management.

Quality control of the activity meter; Controle de qualidade do ativímetro

Energy Technology Data Exchange (ETDEWEB)

Rodrigues, Marlon da Silva Brandão; Sá, Lídia Vasconcelos de, E-mail: nolramsbr@gmail.com [Instituto de Radioproteção e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

2017-07-01

Objective: To carry out a comparative analysis of national and international standards regarding the quality control of the activity meter used in Nuclear Medicine Services in Brazil. Material and methods: Quality control protocols from the International Atomic Energy Agency (IAEA), American Association of Physicists in Medicine (AAPM) and International Electrotechnical Commission (IEC) were pointed out and compared with requirements from both regulatory Brazilian agencies, National Surveillance Agency (ANVISA) and National Nuclear Energy Commission (CNEN). Results: The daily routine tests recommended by the regulatory agencies do not have significant differences; in contrast the tests with higher periodicities like (accuracy, linearity and precision) have differences discrepant. Conclusion: In view of the comparative analysis carried out, it is suggested that the national recommendations for the quality control tests of the activity meter should be checked and evaluated, with emphasis on the semiannual and annual periodicity tests. (author)

Control Systems Cyber Security Standards Support Activities

Energy Technology Data Exchange (ETDEWEB)

Robert Evans

2009-01-01

The Department of Homeland Security’s Control Systems Security Program (CSSP) is working with industry to secure critical infrastructure sectors from cyber intrusions that could compromise control systems. This document describes CSSP’s current activities with industry organizations in developing cyber security standards for control systems. In addition, it summarizes the standards work being conducted by organizations within the sector and provides a brief listing of sector meetings and conferences that might be of interest for each sector. Control systems cyber security standards are part of a rapidly changing environment. The participation of CSSP in the development effort for these standards has provided consistency in the technical content of the standards while ensuring that information developed by CSSP is included.

Active Sticks: a New Dimension in Controller Design

Science.gov (United States)

Repperger, D. W.; Mccollor, D.

1984-01-01

A smart stick controller was built which actively produces a force to interact with the subject's hand and to aid in tracking. When the human tracks in this situation, the man-machine system can be viewed as the combination of two closed loop feedback paths. The inner loop occurs as a result of a tactile information channel effecting the man-controller interaction through force with this stick in the active mode (the stick generates a force) and the passive mode (the stick not generating a force) are reported. The most noteworthy observation is a significant increase in apparent neuromotor bandwidth and consequently better tracking performance.

Rapid Active Power Control of Photovoltaic Systems for Grid Frequency Support

Energy Technology Data Exchange (ETDEWEB)

Hoke, Anderson; Shirazi, Mariko; Chakraborty, Sudipta; Muljadi, Eduard; Maksimovic, Dragan

2017-01-01

As deployment of power electronic coupled generation such as photovoltaic (PV) systems increases, grid operators have shown increasing interest in calling on inverter-coupled generation to help mitigate frequency contingency events by rapidly surging active power into the grid. When responding to contingency events, the faster the active power is provided, the more effective it may be for arresting the frequency event. This paper proposes a predictive PV inverter control method for very fast and accurate control of active power. This rapid active power control method will increase the effectiveness of various higher-level controls designed to mitigate grid frequency contingency events, including fast power-frequency droop, inertia emulation, and fast frequency response, without the need for energy storage. The rapid active power control method, coupled with a maximum power point estimation method, is implemented in a prototype PV inverter connected to a PV array. The prototype inverter's response to various frequency events is experimentally confirmed to be fast (beginning within 2 line cycles and completing within 4.5 line cycles of a severe test event) and accurate (below 2% steady-state error).

Chaotic incommensurate fractional order Rössler system: active control and synchronization

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Baleanu Dumitru

2011-01-01

Full Text Available Abstract In this article, we present an active control methodology for controlling the chaotic behavior of a fractional order version of Rössler system. The main feature of the designed controller is its simplicity for practical implementation. Although in controlling such complex system several inputs are used in general to actuate the states, in the proposed design, all states of the system are controlled via one input. Active synchronization of two chaotic fractional order Rössler systems is also investigated via a feedback linearization method. In both control and synchronization, numerical simulations show the efficiency of the proposed methods.

Phase and gain control policies for robust active vibration control of flexible structures

International Nuclear Information System (INIS)

Zhang, K; Ichchou, M N; Scorletti, G; Mieyeville, F

2013-01-01

The interest of this paper is to develop a general and systematic robust control methodology for active vibration control of flexible structures. For this purpose, first phase and gain control policies are proposed to impose qualitative frequency-dependent requirements on the controller to consider a complete set of control objectives. Then the proposed control methodology is developed by employing phase and gain control policies in the dynamic output feedback H ∞  control: according to the set of control objectives, phase and gain control policies incorporate necessary weighting functions and determine them in a rational and systematic way; on the other hand, with the appropriate weighting functions efficient H ∞  control algorithms can automatically realize phase and gain control policies and generate a satisfactory H ∞  controller. The proposed control methodology can be used for both SISO and MIMO systems with collocated or non-collocated sensors and actuators. In this paper, it is validated on a non-collocated piezoelectric cantilever beam. Both numerical simulations and experimental results demonstrate the effectiveness of the proposed control methodology. (paper)

Piezoelectric pushers for active vibration control of rotating machinery

Science.gov (United States)

Palazzolo, A. B.; Lin, R. R.; Alexander, R. M.; Kascak, A. F.; Montague, J.

1989-01-01

The active control of rotordynamic vibrations and stability by magnetic bearings and electromagnetic shakers have been discussed extensively in the literature. These devices, though effective, are usually large in volume and add significant weight to the stator. The use of piezoelectric pushers may provide similar degrees of effectiveness in light, compact packages. Tests are currently being conducted with piezoelectric pusher-based active vibration control. Results from tests performed on NASA test rigs as preliminary verification of the related theory are presented.

Reducing braking distance by control of semi-active suspension

Energy Technology Data Exchange (ETDEWEB)

Niemz, T.

2007-07-01

This thesis presents a control algorithm for semi-active suspensions to reduce the braking distance of passenger cars. Active shock absorbers are controlled and used to influence the vertical dynamics during ABS-controlled full braking. The core of the approach presented in this paper is based on a switching control logic. The control algorithm is implemented in a compact class passenger car. Test drives on a real road, using a braking machine for reproducibility reasons, have been executed. It could be shown that it is possible to reduce the braking distance by affecting on the vertical dynamics of a passenger car in general. This is the first experimental result of this kind published ever. The amount of reduction depends on the height profile of the testing track chosen and on the initial velocity. On a road with an unevenness comparable to the one on a typical German Autobahn an average reduction of 1-2%, compared to the best passive damping, was achieved. (orig.)

Structural control by the use of piezoelectric active members

Science.gov (United States)

Fanson, J. L.; Chen, J.-C.

1987-01-01

Large Space Structures (LSS) exhibit characteristics which make the LSS control problem different form other control problems. LSS will most likely exhibit low frequency, densely spaced and lightly damped modes. In theory, the number of these modes is infinite. Because these structures are flexible, Vibration Suppression (VS) is an important aspect of LSS operation. In terms of VS, the control actuators should be as low mass as possible, have infinite bandwidth, and be electrically powered. It is proposed that actuators be built into the structure as dual purpose structural elements. A piezoelectric active member is proposed for the control of LSS. Such a device would consist of a piezoelectric actuator and sensor for measuring strain, and screwjack actuator in series for use in quasi-static shape control. An experiment simulates an active member using piezoelectric ceramic thin sheet material on a thin, uniform cantilever beam. The feasibility of using the piezoelectric materials for VS on LSS was demonstrated. Positive positive feedback as a VS control strategy was implemented. Multi-mode VS was achieved with dramatic reduction in dynamic response.

A TAD further: exogenous control of gene activation.

Science.gov (United States)

Mapp, Anna K; Ansari, Aseem Z

2007-01-23

Designer molecules that can be used to impose exogenous control on gene transcription, artificial transcription factors (ATFs), are highly desirable as mechanistic probes of gene regulation, as potential therapeutic agents, and as components of cell-based devices. Recently, several advances have been made in the design of ATFs that activate gene transcription (activator ATFs), including reports of small-molecule-based systems and ATFs that exhibit potent activity. However, the many open mechanistic questions about transcriptional activators, in particular, the structure and function of the transcriptional activation domain (TAD), have hindered rapid development of synthetic ATFs. A compelling need thus exists for chemical tools and insights toward a more detailed portrait of the dynamic process of gene activation.

DNA-binding, catalytic oxidation, C—C coupling reactions and antibacterial activities of binuclear Ru(II thiosemicarbazone complexes: Synthesis and spectral characterization

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Arumugam Manimaran

2012-07-01

Full Text Available New hexa-coordinated binuclear Ru(II thiosemicarbazone complexes of the type {[(B(EPh3(COClRu]2L} (where, E = P or As; B = PPh3 or AsPh3 or pyridine; L = mononucleating NS donor of N-substituted thiosemicarbazones have been synthesized and characterized by elemental analysis, FT-IR, UV–vis and 31P{1H} NMR cyclic voltammetric studies. The DNA-binding studies of Ru(II complexes with calf thymus DNA (CT-DNA were investigated by UV–vis, viscosity measurements, gel-electrophoresis and fluorescence spectroscopy. The new complexes have been used as catalysts in C—C coupling reaction and in the oxidation of alcohols to their corresponding carbonyl compounds by using NMO as co-oxidant and molecular oxygen (O2 atmosphere at ambient temperature. Further, the new binucleating thiosemicarbazone ligands and their Ru(II complexes were also screened for their antibacterial activity against Klebsiella pneumoniae, Shigella sp., Micrococcus luteus, Escherichia coli and Salmonella typhi. From this study, it was found out that the activity of the complexes almost reaches the effectiveness of the conventional bacteriocide.

Experimental Study on Active Control of Surge in a Centrifugal Compression System

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Nie Chaoqun

2000-01-01

Full Text Available An experimental study has been carried out on the active control of surge in a centrifugal compression system. With a computerized on-line control scheme, the surge phenomenon is suppressed and the stable operating range of the system is extended. In order to design the active control scheme and choose the desired parameters of the control system inputs, special emphases have been placed on the development of surge inception and the nonlinear interaction between the system and the actuator. By use of the method designed in the present work, the results of active control onsurge have been demonstrated for the different B parameters, different prescribed criteria and different control frequencies.

Time delay effects on large-scale MR damper based semi-active control strategies

International Nuclear Information System (INIS)

Cha, Y-J; Agrawal, A K; Dyke, S J

2013-01-01

This paper presents a detailed investigation on the robustness of large-scale 200 kN MR damper based semi-active control strategies in the presence of time delays in the control system. Although the effects of time delay on stability and performance degradation of an actively controlled system have been investigated extensively by many researchers, degradation in the performance of semi-active systems due to time delay has yet to be investigated. Since semi-active systems are inherently stable, instability problems due to time delay are unlikely to arise. This paper investigates the effects of time delay on the performance of a building with a large-scale MR damper, using numerical simulations of near- and far-field earthquakes. The MR damper is considered to be controlled by four different semi-active control algorithms, namely (i) clipped-optimal control (COC), (ii) decentralized output feedback polynomial control (DOFPC), (iii) Lyapunov control, and (iv) simple-passive control (SPC). It is observed that all controllers except for the COC are significantly robust with respect to time delay. On the other hand, the clipped-optimal controller should be integrated with a compensator to improve the performance in the presence of time delay. (paper)

Active control of the Chinese Giant Solar Telescope

Science.gov (United States)

Dai, Yichun; Yang, Dehua; Jin, Zhenyu; Liu, Zhong; Qin, Wei

2014-07-01

The Chinese Giant Solar Telescope (CGST) is the next generation solar telescope of China with diameter of 8 meter. The unique feature of CGST is that its primary is a ring, which facilitates the polarization detection and thermal control. In its present design and development phase, two primary mirror patterns are considered. For one thing, the primary mirror is expected to construct with mosaic mirror with 24 trapezoidal (or petal) segments, for another thing, a monolithic mirror is also a candidate for its primary mirror. Both of them depend on active control technique to maintain the optical quality of the ring mirror. As a solar telescope, the working conditions of the CGST are quite different from those of the stellar telescopes. To avoid the image deterioration due to the mirror seeing and dome seeing, especially in the case of the concentration of flux in a solar telescope, large aperture solar projects prefer to adopt open telescopes and open domes. In this circumstance, higher wind loads act on the primary mirror directly, which will cause position errors and figure errors of the primary with matters worse than those of the current 10-meter stellar telescopes with dome protect. Therefore, it gives new challenges to the active control capability, telescope structure design, and wind shielding design. In this paper, the study progress of active control of CGST for its mosaic and monolithic mirror are presented, and the wind effects on such two primary mirrors are also investigated.

Requirements for active resistive wall mode (RWM) feedback control

International Nuclear Information System (INIS)

In, Y; Kim, J S; Chu, M S; Jackson, G L; La Haye, R J; Strait, E J; Liu, Y Q; Marrelli, L; Okabayashi, M; Reimerdes, H

2010-01-01

The requirements for active resistive wall mode (RWM) feedback control have been systematically investigated and established using highly reproducible current-driven RWMs in ohmic discharges in DIII-D. The unambiguous evaluation of active RWM feedback control was not possible in previous RWM studies primarily due to the variability of the onset of the pressure-driven RWMs; the stability of the pressure-driven RWM is thought to be sensitive to various passive stabilization mechanisms. Both feedback control specifications and physics requirements for RWM stabilization have been clarified using the current-driven RWMs in ohmic discharges, when little or no passive stabilization effects are present. The use of derivative gain on top of proportional gain is found to be advantageous. An effective feedback control system should be equipped with a power supply with bandwidth greater than the RWM growth rate. It is beneficial to apply a feedback field that is toroidally phase-shifted from the measured RWM phase in the same direction as the plasma current. The efficacy of the RWM feedback control will ultimately be determined by the plasma fluctuations on internal diagnostics, as well as on external magnetics. The proximity of the feedback coils to the plasma appears to be an important factor in determining the effectiveness of the RWM feedback coils. It is desirable that an RWM feedback control system simultaneously handles error field correction at a low frequency, along with direct RWM feedback at a high frequency. There is an indication of the influence of a second least stable RWM, which had been theoretically predicted but never identified in experiments. A preliminary investigation based on active MHD spectroscopic measurement showed a strong plasma response around 400 Hz where the typical plasma response associated with the first least stable RWM was expected to be negligible. Present active feedback control requirements are based on a single mode assumption, so the

Emergency peripartum hysterectomy, physical and mental consequences: a 6-year study

Directory of Open Access Journals (Sweden)

Denisa-Oana Bălălău

2016-04-01

Full Text Available Emergency peripartum hysterectomy (EPH is performed for massive postpartum hemorrhage following a cesarean delivery or vaginal delivery, in order to save the patient’s life. The current study was performed on a sample of 13.162 patients, which underwent cesarean or vaginal delivery during a period of 6 years, from 2010 to 2015, in Bucur Maternity Hospital. There were two subsequential groups consisting in: 6593 patients with cesarean operations and 6569 patients with vaginal delivery. In 12 cases occurred one or more of the risk factors that lead to EPH, divided equally across the two groups above. The main two types of surgery are a more frequent subtotal hysterectomy, which is the preferred type of EPH as it takes less time and is associated with fewer complications, and a total hysterectomy. The majority of procedures were performed at patients over 35 years old (9 of 12, with a median age of 31,16 (ranging from 21 to 44 years old. The most important risk factor present across the lot was multiparity (11 from 12, with cicatricial uterus being the second one (4 of 12. ICU median time was 4,5 days (ranging from 3 to 15 days, with a median blood transfusion necessity of around 2,4 I.U per patient. There were no mother or newborn reported deaths, neither PTSD following EPH.EPH is a procedure performed as last-resort, life-saving surgery, leaving no time for mental preparation of the patients. This may predispose to negative psychological outcomes, especially because they are not part of decision-making process due to the emergency character of hysterectomy.

Transmission of Turnip yellows virus by Myzus persicae Is Reduced by Feeding Aphids on Double-Stranded RNA Targeting the Ephrin Receptor Protein

Directory of Open Access Journals (Sweden)

Michaël Mulot

2018-03-01

Full Text Available Aphid-transmitted plant viruses are a threat for major crops causing massive economic loss worldwide. Members in the Luteoviridae family are transmitted by aphids in a circulative and non-replicative mode. Virions are acquired by aphids when ingesting sap from infected plants and are transported through the gut and the accessory salivary gland (ASG cells by a transcytosis mechanism relying on virus-specific receptors largely unknown. Once released into the salivary canal, virions are inoculated to plants, together with saliva, during a subsequent feeding. In this paper, we bring in vivo evidence that the membrane-bound Ephrin receptor (Eph is a novel aphid protein involved in the transmission of the Turnip yellows virus (TuYV, Polerovirus genus, Luteoviridae family by Myzus persicae. The minor capsid protein of TuYV, essential for aphid transmission, was able to bind the external domain of Eph in yeast. Feeding M. persicae on in planta- or in vitro-synthesized dsRNA targeting Eph-mRNA (dsRNAEph did not affect aphid feeding behavior but reduced accumulation of TuYV genomes in the aphid's body. Consequently, TuYV transmission efficiency by the dsRNAEph-treated aphids was reproducibly inhibited and we brought evidence that Eph is likely involved in intestinal uptake of the virion. The inhibition of virus uptake after dsRNAEph acquisition was also observed for two other poleroviruses transmitted by M. persicae, suggesting a broader role of Eph in polerovirus transmission. Finally, dsRNAEph acquisition by aphids did not affect nymph production. These results pave the way toward an ecologically safe alternative of insecticide treatments that are used to lower aphid populations and reduce polerovirus damages.

Active Control of Inlet Noise on the JT15D Turbofan Engine

Science.gov (United States)

Smith, Jerome P.; Hutcheson, Florence V.; Burdisso, Ricardo A.; Fuller, Chris R.

1999-01-01

This report presents the key results obtained by the Vibration and Acoustics Laboratories at Virginia Tech over the year from November 1997 to December 1998 on the Active Noise Control of Turbofan Engines research project funded by NASA Langley Research Center. The concept of implementing active noise control techniques with fuselage-mounted error sensors is investigated both analytically and experimentally. The analytical part of the project involves the continued development of an advanced modeling technique to provide prediction and design guidelines for application of active noise control techniques to large, realistic high bypass engines of the type on which active control methods are expected to be applied. Results from the advanced analytical model are presented that show the effectiveness of the control strategies, and the analytical results presented for fuselage error sensors show good agreement with the experimentally observed results and provide additional insight into the control phenomena. Additional analytical results are presented for active noise control used in conjunction with a wavenumber sensing technique. The experimental work is carried out on a running JT15D turbofan jet engine in a test stand at Virginia Tech. The control strategy used in these tests was the feedforward Filtered-X LMS algorithm. The control inputs were supplied by single and multiple circumferential arrays of acoustic sources equipped with neodymium iron cobalt magnets mounted upstream of the fan. The reference signal was obtained from an inlet mounted eddy current probe. The error signals were obtained from a number of pressure transducers flush-mounted in a simulated fuselage section mounted in the engine test cell. The active control methods are investigated when implemented with the control sources embedded within the acoustically absorptive material on a passively-lined inlet. The experimental results show that the combination of active control techniques with fuselage

Active Molecular Plasmonics: Controlling Plasmon Resonances with Molecular Switches

KAUST Repository

Zheng, Yue Bing

2009-02-11

A gold nanodisk array, coated with bistable, redox-controllable [2]rotaxane molecules, when exposed to chemical oxidants and reductants, undergoes switching of its plasmonic properties reversibly. By contrast, (i) bare gold nanodisks and (ii) disks coated with a redox-active, but mechanically inert, control compound do not display surface-plasmon-based switching. Along with calculations based on time-dependent density functional theory, these experimental observations suggest that the nanoscale movements within surface-bound “molecular machines” can be used as the active components in plasmonic devices.

Active Molecular Plasmonics: Controlling Plasmon Resonances with Molecular Switches

KAUST Repository

Zheng, Yue Bing; Yang, Ying-Wei; Jensen, Lasse; Fang, Lei; Juluri, Bala Krishna; Flood, Amar H.; Weiss, Paul S.; Stoddart, J. Fraser; Huang, Tony Jun

2009-01-01

A gold nanodisk array, coated with bistable, redox-controllable [2]rotaxane molecules, when exposed to chemical oxidants and reductants, undergoes switching of its plasmonic properties reversibly. By contrast, (i) bare gold nanodisks and (ii) disks coated with a redox-active, but mechanically inert, control compound do not display surface-plasmon-based switching. Along with calculations based on time-dependent density functional theory, these experimental observations suggest that the nanoscale movements within surface-bound “molecular machines” can be used as the active components in plasmonic devices.

Using behavioural activation in the treatment of depression: a control theory perspective.

Science.gov (United States)

McEvoy, P; Law, A; Bates, R; Hylton, K; Mansell, W

2013-12-01

Behavioural activation is an intervention that can be used to counteract the typical patterns of withdrawal, avoidance and inactivity that characterize depression. This paper examines the processes of change that may occur during behavioural activation from the perspective of control theory. Some of the key concepts that are associated with control theory are introduced and the process of change that may occur during behavioural activation is illustrated using two case studies. The case studies provide anecdotal evidence which supports the hypothesis that the effective implementation of behavioural activation may depend upon clients being able to retain or regain the sense of control that they value. The differences between a control-theory-based approach and more orthodox behavioural and cognitive approaches are highlighted and the implications of these differences are discussed. Flexible approaches that are informed by control theory, may offer a useful alternative to the more established behavioural and cognitive approaches towards behavioural activation. © 2012 John Wiley & Sons Ltd.

Modulation of ephrinB2 leads to increased angiogenesis in ischemic myocardium and endothelial cell proliferation

International Nuclear Information System (INIS)

Mansson-Broberg, Agneta; Siddiqui, Anwar J.; Genander, Maria; Grinnemo, Karl-Henrik; Hao Xiaojin; Andersson, Agneta B.; Waerdell, Eva; Sylven, Christer; Corbascio, Matthias

2008-01-01

Eph/ephrin signaling is pivotal in prenatal angiogenesis while its potential role in postnatal angiogenesis largely remains to be explored. Therefore its putative angiogenic and therapeutic effects were explored in endothelium and in myocardial ischemia. In culture of human aortic endothelial cells the fusion protein ephrinB2-Fc induced cell proliferation (p < 0.0005) and in the murine aortic ring model ephrinB2-Fc induced increased sprouting (p < 0.05). Myocardial infarction was induced by ligation of the left anterior descending artery in mouse. During the following 2 weeks mRNA of the receptor/ligand pair EphB4/ephrinB2 was expressed dichotomously (p < 0.05) and other Eph/ephrin pairs were expressed to a lesser degree. Twenty-four hours after intraperitoneal administration of ephrinB2-Fc it was detected in abundance throughout the myocardium along capillaries, showing signs of increased mitosis. After 4 weeks the capillary density was increased 28% in the periinfarcted area (p < 0.05) to a level not different from healthy regions of the heart where no change was observed. These results implicate that EphB4/ephrinB2 is an important signaling pathway in ischemic heart disease and its modulation may induce therapeutic angiogenesis

Experimental Active Control of Automotive Disc Brake Rotor Squeal Using Dither

Science.gov (United States)

CUNEFARE, K. A.; GRAF, A. J.

2002-02-01

This paper presents an experimental investigation into the application of “dither” control for the active control and suppression of automobile disc brake squeal. Dither control is characterized by the application of a control effort at a frequency higher than the disturbance to be controlled. In the particular system considered here, a vibro-acoustic analysis of a disc brake system during squeal determined the acoustic squeal signature to be emanating from the brake rotor. This squeal was eliminated, and could even be prevented from occurring, through the application of a harmonic force with a frequency higher than the squeal frequency. The harmonic force was generated by a stack of piezoelectric elements placed within the brake's caliper piston. The harmonic force represented a small variation about the mean clamping force exerted by the brake upon the rotor. The high-frequency vibration in the brake system due to the action of the control system was not heard if an ultrasonic control frequency was used. More importantly, the active control system is shown to be able to prevent squeal from even occurring. This gives rise to a possible active control system integrated into the brake system of automobiles to prevent squeal.

Acceleration Feedback-Based Active and Semi-Active Seismic Response Control of Rail-Counterweight Systems of Elevators

Directory of Open Access Journals (Sweden)

Rildova

2005-01-01

Full Text Available Based on the observations in the past earthquake events, the traction elevators in buildings are known to be vulnerable to earthquake induced ground motions. Among several components of an elevator, the counterweight being heaviest is also known to be more susceptible than others. The inertial effects of the counterweight can overstress the guide rails on which it moves. Here we investigate to use the well-known acceleration feedback-based active and semi-active control methods to reduce stresses in the rails. The only way a control action can be applied to a moving counterweight-rail system is through a mass damper placed in the plane of the counterweight. For this, a part of the counterweight mass can be configured as a mass damper attached to a small actuator for an active scheme or to a magneto-rheological damper for a semi-active scheme. A comprehensive numerical study is conducted to evaluate the effectiveness of the proposed configuration of control system. It is observed that the two control schemes are effective in reducing the stress response by about 20 to 25% and improve the system fragility over a good range of seismic intensities.

Electron-phonon contribution to the phonon and excited electron (hole) linewidths in bulk Pd

International Nuclear Information System (INIS)

Sklyadneva, I Yu; Leonardo, A; Echenique, P M; Eremeev, S V; Chulkov, E V

2006-01-01

We present an ab initio study of the electron-phonon (e-ph) coupling and its contribution to the phonon linewidths and to the lifetime broadening of excited electron and hole states in bulk Pd. The calculations, based on density-functional theory, were carried out using a linear-response approach in the plane-wave pseudopotential representation. The obtained results for the Eliashberg spectral function α 2 F(ω), e-ph coupling constant λ, and the contribution to the lifetime broadening, Γ e-ph , show strong dependence on both the energy and momentum of an electron (hole) state. The calculation of phonon linewidths gives, in agreement with experimental observations, an anomalously large broadening for the transverse phonon mode T 1 in the Σ direction. In addition, this mode is found to contribute most strongly to the electron-phonon scattering processes on the Fermi surface

Unified Brake Service by a Hierarchical Controller for Active Deceleration Control in an Electric and Automated Vehicle

Directory of Open Access Journals (Sweden)

Yuliang Nie

2017-12-01

Full Text Available Unified brake service is a universal service for generating certain brake force to meet the demand deceleration and is essential for an automated driving system. However, it is rather difficult to control the pressure in the wheel cylinders to reach the target deceleration of the automated vehicle, which is the key issue of the active deceleration control system (ADC. This paper proposes a hierarchical control method to actively control vehicle deceleration with active-brake actuators. In the upper hierarchical, the target pressure of wheel cylinders is obtained by dynamic equations of a pure electric vehicle. In the lower hierarchical, the solenoid valve instructions and the pump speed of hydraulic control unit (HCU are determined to satisfy the desired pressure with the feedback of measured wheel cylinder pressure by pressure sensors. Results of road experiments of a pure electric and automated vehicle indicate that the proposed method realizes the target deceleration accurately and efficiently.

An Active Capacitor with Self-Power and Internal Feedback Control Signals

DEFF Research Database (Denmark)

Wang, Haoran; Wang, Huai

2017-01-01

This paper proposes a concept of two-terminal active capacitor implemented by power semiconductor switches and passive elements. The active capacitor has the same level of convenience as a passive one with two power terminals only. A control strategy that does not require any external feedback...... signal is proposed and a self-power scheme for gate drivers and the controller is applied to achieve the two-terminal active capacitor. The concept, control method, self-power scheme, efficiency, and impedance characteristics of the active capacitor are presented. A case study of the proposed active...... capacitor for a capacitive DC-link application is discussed. The results reveal a significantly lower overall energy storage of passive elements and a reduced cost to fulfill a specific reliability target, compared to a passive capacitor solution. Proof-of-concept experimental results are given to verify...

Wind Turbine Rotors with Active Vibration Control

DEFF Research Database (Denmark)

Svendsen, Martin Nymann

that the basic modes of a wind turbine blade can be effectively addressed by an in-blade ‘active strut’ actuator mechanism. The importance of accounting for background mode flexibility is demonstrated. Also, it is shown that it is generally possible to address multiple beam modes with multiple controllers, given...... in the targeted modes and the observed spill-over to other modes is very limited and generally stabilizing. It is shown that physical controller positioning for reduced background noise is important to the calibration. By simulation of the rotor response to both simple initial conditions and a stochastic wind......This thesis presents a framework for structural modeling, analysis and active vibration damping of rotating wind turbine blades and rotors. A structural rotor model is developed in terms of finite beam elements in a rotating frame of reference. The element comprises a representation of general...

Testing a workplace physical activity intervention: a cluster randomized controlled trial.

Science.gov (United States)

McEachan, Rosemary R C; Lawton, Rebecca J; Jackson, Cath; Conner, Mark; Meads, David M; West, Robert M

2011-04-11

Increased physical activity levels benefit both an individuals' health and productivity at work. The purpose of the current study was to explore the impact and cost-effectiveness of a workplace physical activity intervention designed to increase physical activity levels. A total of 1260 participants from 44 UK worksites (based within 5 organizations) were recruited to a cluster randomized controlled trial with worksites randomly allocated to an intervention or control condition. Measurement of physical activity and other variables occurred at baseline, and at 0 months, 3 months and 9 months post-intervention. Health outcomes were measured during a 30 minute health check conducted in worksites at baseline and 9 months post intervention. The intervention consisted of a 3 month tool-kit of activities targeting components of the Theory of Planned Behavior, delivered in-house by nominated facilitators. Self-reported physical activity (measured using the IPAQ short-form) and health outcomes were assessed. Multilevel modelling found no significant effect of the intervention on MET minutes of activity (from the IPAQ) at any of the follow-up time points controlling for baseline activity. However, the intervention did significantly reduce systolic blood pressure (B=-1.79 mm/Hg) and resting heart rate (B=-2.08 beats) and significantly increased body mass index (B=.18 units) compared to control. The intervention was found not to be cost-effective, however the substantial variability round this estimate suggested that further research is warranted. The current study found mixed support for this worksite physical activity intervention. The paper discusses some of the tensions involved in conducting rigorous evaluations of large-scale randomized controlled trials in real-world settings. © 2011 McEachan et al; licensee BioMed Central Ltd.

Optimisation of active suspension control inputs for improved performance of active safety systems

Science.gov (United States)

Čorić, Mirko; Deur, Joško; Xu, Li; Tseng, H. Eric; Hrovat, Davor

2018-01-01

A collocation-type control variable optimisation method is used to investigate the extent to which the fully active suspension (FAS) can be applied to improve the vehicle electronic stability control (ESC) performance and reduce the braking distance. First, the optimisation approach is applied to the scenario of vehicle stabilisation during the sine-with-dwell manoeuvre. The results are used to provide insights into different FAS control mechanisms for vehicle performance improvements related to responsiveness and yaw rate error reduction indices. The FAS control performance is compared to performances of the standard ESC system, optimal active brake system and combined FAS and ESC configuration. Second, the optimisation approach is employed to the task of FAS-based braking distance reduction for straight-line vehicle motion. Here, the scenarios of uniform and longitudinally or laterally non-uniform tyre-road friction coefficient are considered. The influences of limited anti-lock braking system (ABS) actuator bandwidth and limit-cycle ABS behaviour are also analysed. The optimisation results indicate that the FAS can provide competitive stabilisation performance and improved agility when compared to the ESC system, and that it can reduce the braking distance by up to 5% for distinctively non-uniform friction conditions.

Innovation in Active Vibration Control Strategy of Intelligent Structures

Directory of Open Access Journals (Sweden)

A. Moutsopoulou

2014-01-01

Full Text Available Large amplitudes and attenuating vibration periods result in fatigue, instability, and poor structural performance. In light of past approaches in this field, this paper intends to discuss some innovative approaches in vibration control of intelligent structures, particularly in the case of structures with embedded piezoelectric materials. Control strategies are presented, such as the linear quadratic control theory, as well as more advanced theories, such as robust control theory. The paper presents sufficiently a recognizable advance in knowledge of active vibration control in intelligent structures.

Design and control of hybrid active power filters

CERN Document Server

Lam, Chi-Seng

2014-01-01

Design and Control of Hybrid Active Power Filters presents an overview of the current quality problems and their compensators. To get a balance between the system cost and performance, hybrid active power filters (HAPFs) are valuable. The book presents the coverage of resonance phenomena prevention capability, filtering performance and system robustness analysis of HAPF; nonlinear inverter current slope characteristics and their linear operation region requirement analysis of the hysteresis PWM for the HAPF; minimum inverter capacity design procedure of HAPF, adaptive dc-link voltage controller for the HAPF and the real design example of a 220V 10kVA HAPF, in which the system performance analysis method, minimum dc voltage deduction concept and adaptive dc voltage idea can be further extended into the other active compensators, such as APF, static synchronous compensator STATCOM, etc. This book will benefit researchers, graduate students, and electrical power engineers in the field of power-quality compensati...

Analysis and planning of dose-finding studies with active control

International Nuclear Information System (INIS)

Helms, Hans-Joachim

2014-01-01

In the clinical development of radiopharmaceuticals the dose finding plays an important role. The contribution is focused on the evaluation and planning of dose finding studies with active control. It is of primary interest to find the lowest dose that yields the same efficacy as the active control. Besides the target dose confidence intervals are of importance to describe the quality of the target dose estimation. The calculation of case numbers and the determination of the dose steps to be studied are challenging under practical conditions. The contribution covers the demonstration of the statistical model the parameter estimation and the asymptotic properties based on maximum likelihood theory, the spline-based evaluation of nonlinear dose finding studies with active control and the planning of design and number of cases.

MODELING MERCURY CONTROL WITH POWDERED ACTIVATED CARBON

Science.gov (United States)

The paper presents a mathematical model of total mercury removed from the flue gas at coal-fired plants equipped with powdered activated carbon (PAC) injection for Mercury control. The developed algorithms account for mercury removal by both existing equipment and an added PAC in...

Research on LQR optimal control method of active engine mount

Science.gov (United States)

Huan, Xie; Yu, Duan

2018-04-01

In this paper, the LQR control method is applied to the active mount of the engine, and a six-cylinder engine excitation model is established. Through the joint simulation of AMESim and MATLAB, the vibration isolation performance of the active mount system and the passive mount system is analyzed. Excited by the multi-engine operation, the simulation results of the vertical displacement, acceleration and dynamic deflection of the vehicle body show that the vibration isolation capability of the active mount system is superior to that of the passive mount system. It shows that compared with the passive mount, LQR active mount can greatly improve the vibration isolation performance, which proves the feasibility and effectiveness of the LQR control method.

Self-controlled feedback facilitates motor learning in both high and low activity individuals.

Science.gov (United States)

Fairbrother, Jeffrey T; Laughlin, David D; Nguyen, Timothy V

2012-01-01

The purpose of this study was to determine if high and low activity individuals differed in terms of the effects of self-controlled feedback on the performance and learning of a movement skill. The task consisted of a blindfolded beanbag toss using the non-preferred arm. Participants were pre-screened according to their physical activity level using the International Physical Activity Questionnaire. An equal number of high activity (HA) and low activity (LA) participants were assigned to self-control (SC) and yoked (YK) feedback conditions, creating four groups: Self-Control-High Activity; Self-Control-Low Activity; Yoked-High Activity; and Yoked-Low Activity. SC condition participants were provided feedback whenever they requested it, while YK condition participants received feedback according to a schedule created by their SC counterpart. Results indicated that the SC condition was more accurate than the YK condition during acquisition and transfer phases, and the HA condition was more accurate than the LA condition during all phases of the experiment. A post-training questionnaire indicated that participants in the SC condition asked for feedback mostly after what they perceived to be "good" trials; those in the YK condition indicated that they would have preferred to receive feedback after "good" trials. This study provided further support for the advantages of self-controlled feedback when learning motor skills, additionally showing benefits for both active and less active individuals. The results suggested that the provision of self-controlled feedback to less active learners may be a potential avenue to teaching motor skills necessary to engage in greater amounts of physical activity.

Predesigned surface patterns and topological defects control the active matter.

Science.gov (United States)

Turiv, Taras; Peng, Chenhui; Guo, Yubing; Wei, Qi-Huo; Lavrentovich, Oleg

Active matter exhibits remarkable patterns of never-ending dynamics with giant fluctuations of concentration, varying order, nucleating and annihilating topological defects. These patterns can be seen in active systems of both biological and artificial origin. A fundamental question is whether and how one can control this chaotic out-of-equilibrium behavior. We demonstrate a robust control of local concentration, trajectories of active self-propelled units and the net flows of active bacteria Bacillus Substilis by imposing pre-designed surface patterns of orientational order in a water-based lyotropic chromonic liquid crystal. The patterns force the bacteria to gather into dynamic swarms with spatially modulated concentration and well-defined polarity of motion. Topological defects produce net motion of bacteria with a unidirectional circulation, while pairs of defects induce a pumping action. The qualitative features of the dynamics can be explained by interplay of curvature and activity, in particular, by ability of mixed splay-bend curvatures to generate threshold-less active flows. The demonstrated level of control opens opportunities in engineering materials and devices that mimic rich functionality of living systems. This work was supported by NSF Grants DMR-1507637, DMS-1434185, CMMI-1436565, by the Petroleum Research Grant PRF# 56046-ND7 administered by the American Chemical Society.

Being active supports client control over health care.

Science.gov (United States)

Fiveash, Barb; Nay, Rhonda

2004-10-01

The purpose of this study was to identify how healthcare clients achieve and maintain a sense of control over their health. The literature review conducted refers to: (i) key definitions of control, (ii) locus of control, and (iii) control and wellbeing. Participants with a range of acute and chronic health conditions and who had been hospitalised at some point were selected for the study. Symbolic interactionism (Blumer, 1969) and modified grounded theory of Strauss & Corbin (1998) provided the frameworks for this study. During the six month study period, data were collected from sixty participants and included interviews, participant observation, reviewing participants' records (nursing care plans, nursing notes and case histories), the nursing units' philosophy, organisational charts, policies and procedures, annual reports, consumer brochures and any other relevant information sources. Findings from the study indicated that participants moved from feeling vulnerable to having a sense of control through to being purposefully active. Vulnerability was associated with: (i) having limited choices in respect to their health, (ii) lacking adequate health information to make choices, (iii) being ignored by health providers with respect to their needs, and (iv) lacking friend/family supports. Purposefully activating was associated with three major categories: (i) reflecting, (ii) being self-determiningly involved and (iii) normalising. Findings from this study could be used by health care clients who want a sense of control over their health care, and also by health care providers who wish to support clients in the healthcare process.

Off-axis Modal Active Vibration Control Of Rotational Vibrations

NARCIS (Netherlands)

Babakhani, B.; de Vries, Theodorus J.A.; van Amerongen, J.

Collocated active vibration control is an effective and robustly stable way of adding damping to the performance limiting vibrations of a plant. Besides the physical parameters of the Active Damping Unit (ADU) containing the collocated actuator and sensor, its location with respect to the

Active Fault Tolerant Control for Ultrasonic Piezoelectric Motor

Science.gov (United States)

Boukhnifer, Moussa

2012-07-01

Ultrasonic piezoelectric motor technology is an important system component in integrated mechatronics devices working on extreme operating conditions. Due to these constraints, robustness and performance of the control interfaces should be taken into account in the motor design. In this paper, we apply a new architecture for a fault tolerant control using Youla parameterization for an ultrasonic piezoelectric motor. The distinguished feature of proposed controller architecture is that it shows structurally how the controller design for performance and robustness may be done separately which has the potential to overcome the conflict between performance and robustness in the traditional feedback framework. A fault tolerant control architecture includes two parts: one part for performance and the other part for robustness. The controller design works in such a way that the feedback control system will be solely controlled by the proportional plus double-integral PI2 performance controller for a nominal model without disturbances and H∞ robustification controller will only be activated in the presence of the uncertainties or an external disturbances. The simulation results demonstrate the effectiveness of the proposed fault tolerant control architecture.

Controls on desert dune activity - a geospatial approach

Science.gov (United States)

Lancaster, N.; Hesse, P. P.

2017-12-01

Desert and other inland dunes occur on a wide spectrum of activity (defined loosely as the proportion of the surface area subject to sand movement) from unvegetated to sparsely vegetated "active" dunes through discontinuously vegetated inactive dunes to completely vegetated and degraded dunes. Many of the latter are relicts of past climatic conditions. Although field studies and modeling of the interactions between winds, vegetation cover, and dune activity can provide valuable insights, the response of dune systems to climate change and variability past, present, and future has until now been hampered by the lack of pertinent observational data on geomorphic and climatic boundary conditions and dune activity status for most dune areas. We have developed GIS-based approach that permits analysis of boundary conditions and controls on dune activity at a range of spatial scales from dunefield to global. In this approach, the digital mapping of dune field and sand sea extent has been combined with systematic observations of dune activity at 0.2° intervals from high resolution satellite image data, resulting in four classes of activity. 1 km resolution global gridded datasets for the aridity index (AI); precipitation, satellite-derived percent vegetation cover; and estimates of sand transport potential (DP) were re-sampled for each 0.2° grid cell, and dune activity was compared to vegetation cover, sand transport potential, precipitation, and the aridity index. Results so far indicate that there are broad-scale relationships between dunefield mean activity, climate, and vegetation cover. However, the scatter in the data suggest that other local factors may be at work. Intra-dune field patterns are complex in many cases. Overall, much more work needs to be done to gain a full understanding of controls at different spatial and temporal scales, which can be faciliated by this spatial database.

Semi-active H∞ control of high-speed railway vehicle suspension with magnetorheological dampers

Science.gov (United States)

Zong, Lu-Hang; Gong, Xing-Long; Xuan, Shou-Hu; Guo, Chao-Yang

2013-05-01

In this paper, semi-active H∞ control with magnetorheological (MR) dampers for railway vehicle suspension systems to improve the lateral ride quality is investigated. The proposed semi-active controller is composed of a H∞ controller as the system controller and an adaptive neuro-fuzzy inference system (ANFIS) inverse MR damper model as the damper controller. First, a 17-degree-of-freedom model for a full-scale railway vehicle is developed and the random track irregularities are modelled. Then a modified Bouc-Wen model is built to characterise the forward dynamic characteristics of the MR damper and an inverse MR damper model is built with the ANFIS technique. Furthermore, a H∞ controller composed of a yaw motion controller and a rolling pendulum motion (lateral motion+roll motion) controller is established. By integrating the H∞ controller with the ANFIS inverse model, a semi-active H∞ controller for the railway vehicle is finally proposed. Simulation results indicate that the proposed semi-active suspension system possesses better attenuation ability for the vibrations of the car body than the passive suspension system.

Two-sensor control in active vibration isolation using hard mounts

NARCIS (Netherlands)

Beijen, M.A.; Tjepkema, D.; van Dijk, J.

To isolate precision machines from floor vibrations, active vibration isolators are often applied. In this paper, a two-sensor control strategy, based on acceleration feedback and force feedback, is proposed for an active vibration isolator using a single-axis active hard mount. The hard mount

Two-sensor control in active vibration isolation using hard mounts

NARCIS (Netherlands)

Beijen, M.A.; Tjepkema, D.; van Dijk, Johannes

2014-01-01

To isolate precision machines from floor vibrations, active vibration isolators are often applied. In this paper, a two-sensor control strategy, based on acceleration feedback and force feedback, is proposed for an active vibration isolator using a single-axis active hard mount. The hard mount

Satellite Dynamic Damping via Active Force Control Augmentation

Science.gov (United States)

Varatharajoo, Renuganth

2012-07-01

An approach that incorporates the Active Force Control (AFC) technique into a conventional Proportional-Derivative (PD) controller is proposed for a satellite active dynamic damping towards a full attitude control. The AFC method has been established to facilitate a robust motion control of dynamical systems in the presence of disturbances, parametric uncertainties and changes that are commonly prevalent in the real-world environment. The usefulness of the method can be extended by introducing intelligent mechanisms to approximate the mass or inertia matrix of the dynamic system to trigger the compensation effect of the controller. AFC is a technique that relies on the appropriate estimation of the inertial or mass parameters of the dynamic system and the measurements of the acceleration and force signals induced by the system if practical implementation is ever considered. In AFC, it is shown that the system subjected to a number of disturbances remains stable and robust via the compensating action of the control strategy. We demonstrate that it is possible to design a spacecraft attitude feedback controller that will ensure the system dynamics set point remains unchanged even in the presence of the disturbances provided that the actual disturbances can be modeled effectively. In order to further facilitate this analysis, a combined energy and attitude control system (CEACS) is proposed as a model satellite attitude control actuator. All the governing equations are established and the proposed satellite attitude control architecture is made amenable to numerical treatments. The results show that the PD-AFC attitude damping performances are superiorly better than that of the solely PD type. It is also shown that the tunings of the AFC system gains are crucial to ensure a better attitude damping performance and this process is mandatory for AFC systems. Finally, the results demonstrate an important satellite dynamic damping enhancement capability using the AFC

Re-active Passive (RAP) Devices for Control of Noise Transmission through a Panel

Science.gov (United States)

Carneal, James P.; Giovanardi, Marco; Fuller, Chris R.; Palumbo, Daniel L.

2008-01-01

Re-Active Passive (RAP) devices have been developed to control low frequency (transmission through a panel. These devices use a combination of active, re-active, and passive technologies packaged into a single unit to control a broad frequency range utilizing the strength of each technology over its best suited frequency range. The RAP device uses passive constrained layer damping to cover the relatively high frequency range (>200 Hz), reactive distributed vibration absorber) to cover the medium frequency range (75 to 250 Hz), and active control for controlling low frequencies (transmission through a panel mounted in a transmission loss test facility. Experimental results are presented for the bare panel, and combinations of passive treatment, reactive treatment, and active control. Results indicate that three RAP devices were able to increase the overall broadband (15-1000 Hz) transmission loss by 9.4 dB. These three devices added a total of 285 grams to the panel mass of 6.0 kg, or approximately 5%, not including control electronics.

Self-controlled feedback facilitates motor learning in both high and low activity individuals

Directory of Open Access Journals (Sweden)

Jeffrey T. Fairbrother

2012-08-01

Full Text Available The purpose of this study was to determine if high and low activity individuals differed in terms of the effects of self-controlled feedback on the performance and learning of a movement skill. The task consisted of a blindfolded beanbag toss using the non-preferred arm. Participants were pre-screened according to their physical activity level using the International Physical Activity Questionnaire. An equal number of high activity (HA and low activity (LA participants were assigned to self-control (SC and yoked (YK feedback conditions, creating four groups: Self-Control High Activity (SC-HA; Self-Control Low Activity (SC-LA; Yoked High Activity (YK-HA; and Yoked Low Activity (YK-LA. SC condition participants were provided feedback whenever they requested it, while YK condition participants received feedback according to a schedule created by their SC counterpart. Results indicated that the SC condition was more accurate than the YK condition during acquisition and transfer phases, and the HA condition was more accurate than the LA condition during all phases of the experiment. A post-training questionnaire indicated that participants in the SC condition asked for feedback mostly after what they perceived to be good trials; those in the YK condition indicated that they would have preferred to receive feedback after good trials. This study provided further support for the advantages of self-controlled feedback when learning motor skills, additionally showing benefits for both active and less active individuals. The results suggested that the provision of self-controlled feedback to less active learners may be a potential avenue to teaching motor skills necessary to engage in greater amounts of physical activity.

Control of telematic and informatics workers' activities: some legal-computing considerations

Directory of Open Access Journals (Sweden)

Giovanni Ziccardi

2016-02-01

Full Text Available The evolution of the technological control of the workers is closely related to the improvement of technological tools. From an unsophisticated control mode, targeting the environment and operated through videocameras, the actual framework consists in embedded control tools strictly related to the technologies that are given to the workers for their daily activity.Thanks to software installed on network servers, mobile phones, tablets and computers, it is possibile now to operate a full control activity which do not distinguish, in most cases, between control over the data related to the employment contract and control over the personal data of the subject and over his private life. This article will address, from a legal informatics point of view, the most common tools to operate such controls.

A review of active control approaches in stabilizing combustion systems in aerospace industry

Science.gov (United States)

Zhao, Dan; Lu, Zhengli; Zhao, He; Li, X. Y.; Wang, Bing; Liu, Peijin

2018-02-01

Self-sustained combustion instabilities are one of the most plaguing challenges and problems in lean-conditioned propulsion and land-based engine systems, such as rocket motors, gas turbines, industrial furnace and boilers, and turbo-jet thrust augmenters. Either passive or active control in open- or closed-loop configurations can be implemented to mitigate such instabilities. One of the classical disadvantages of passive control is that it is only implementable to a designed combustor over a limited frequency range and can not respond to the changes in operating conditions. Compared with passive control approaches, active control, especially in closed-loop configuration is more adaptive and has inherent capacity to be implemented in practice. The key components in closed-loop active control are 1) sensor, 2) controller (optimization algorithm) and 3) dynamic actuator. The present work is to outline the current status, technical challenges and development progress of the active control approaches (in open- or closed-loop configurations). A brief description of feedback control, adaptive control, model-based control and sliding mode control are provided first by introducing a simplified Rijke-type combustion system. The modelled combustion system provides an invaluable platform to evaluate the performance of these feedback controllers and a transient growth controller. The performance of these controllers are compared and discussed. An outline of theoretical, numerical and experimental investigations are then provided to overview the research and development progress made during the last 4 decades. Finally, potential, challenges and issues involved with the design, application and implementation of active combustion control strategies on a practical engine system are highlighted.

Active vibrations control of journal bearings with the use of piezoactuators

Science.gov (United States)

Tůma, Jiří; Šimek, Jiří; Škuta, Jaromír; Los, Jaroslav

2013-04-01

Rotor instability is one of the most serious problems of high-speed rotors supported by sliding bearings. With constantly increasing parameters, new machines problems with rotor instability are encountered more and more often. Even though there are many solutions based on passive improvement of the bearing geometry to enlarge the operational speed range of the journal bearing, the paper deals with a working prototype of a system for the active vibration control of journal bearings with the use of piezoactuators. The controllable journal bearing is a part of a test rig, which consists of a rotor driven by an inductive motor up to 23,000 rpm. The actively controlled journal bearing consists of a movable bushing, which is actuated by two piezoactuators. The journal vibration is measured by a pair of proximity probes. The control system enables run-up, coast-down and steady-state rotation. A real-time simulator dSpace encloses the control loop. Force produced by piezoactuators and acting at the bushing is controlled according to error signals derived from the proximity probe output signals. As it was proved by experiments the active vibration control extends considerably the range of the operational speed.

A model for signal processing and predictive control of semi-active ...

Indian Academy of Sciences (India)

Abstract. The theory for structural control has been well developed and applied to perform excellent energy dissipation using dampers. Both active and semi-active control systems may be used to decide on the optimal switch point of the damper based on the current and past structural responses to the excitation of external.

Mitogen-activated protein kinase phosphatase-1 expression in macrophages is controlled by lymphocytes during macrophage activation.

Science.gov (United States)

Luo, Chong; Yang, Xiqiang; Yao, Lan; Jiang, Liping; Liu, Wei; Li, Xin; Wang, Lijia

2012-01-01

The viewpoints on the control of innate immune cells by the adaptive immune system during sepsis remain controversial. Mitogen-activated protein kinase phosphatase-1 (MKP-1) is essential to the negative control of innate immunity and suppresses the activation of macrophages by inhibiting activated mitogen-activated protein kinase (MAPK). The purpose of the current study was to observe inflammatory response and macrophage activation in mice with severe combined immunodeficiency (SCID) with endotoxemia and to determine the role of MKP-1 in the control of macrophage activation by the adaptive immune system. Endotoxemia was induced in wild-type and SCID mice by an intraperitoneal injection of lipopolysaccharide (LPS), and all of the SCID mice died. SCID mice produced more inflammatory cytokines than BALB/c mice systemically and locally. TNF-α mRNA expression was higher and MKP-1 mRNA expression was lower in peritoneal macrophages (PMa) from SCID mice compared to PMa from wild-type mice after and even before LPS injection. Thioglycollate-stimulated PMa from wild-type mice were stimulated with LPS in vitro in the presence or absence of pan-T cells. The levels of TNF-α and IL-6 were higher in the supernatants from PMa cultured alone compared to PMa co-cultured with pan-T cells, and PMa MKP-1 mRNA and protein expression were higher when PMa were co-cultured with pan-T cells. Therefore, pan-T cells can up-regulate MKP-1 expression in macrophages and inhibit the secretion of inflammatory cytokines secretion by macrophages. In SCID mice, lymphocyte deficiency, especially T cell deficiency, causes insufficient MKP-1 expression in macrophages, which can be responsible for the severe inflammation and bad prognosis of septic SCID mice. MKP-1 plays an important role in the control of macrophage activation by the adaptive immune system.

An Efficient Modal Control Strategy for the Active Vibration Control of a Truss Structure

Directory of Open Access Journals (Sweden)

Ricardo Carvalhal

2007-01-01

Full Text Available In this paper an efficient modal control strategy is described for the active vibration control of a truss structure. In this approach, a feedback force is applied to each mode to be controlled according to a weighting factor that is determined by assessing how much each mode is excited by the primary source. The strategy is effective provided that the primary source is at a fixed position on the structure, and that the source is stationary in the statistical sense. To test the effectiveness of the control strategy it is compared with an alternative, established approach namely, Independent Modal Space Control (IMSC. Numerical simulations show that with the new strategy it is possible to significantly reduce the control effort required, with a minimal reduction in control performance.

Estimation of the effect of molybdenum on chemical and electrochemical stability of iron-based alloys

International Nuclear Information System (INIS)

Tyurin, A.G.

2003-01-01

The E-pH diagram for Mo-H 2 O system is made more precise. It is shown that a passivating film on molybdenum in weakly acid, neutral and alkali solutions may constitute MoO 2 only. In strongly acid solutions at anodic polarization the film should transform according to the following scheme: MoO 2 → Mo 4 O 11 → Mo 9 O 26 → MoO 3 . Sections of a Fe-Mo-O system phase diagram and a Fe-Mo-H 2 O system E-pH diagram at 25 deg C are plotted. MoO 2 is found to be a product of iron-molybdenum alloy oxidation in the air and in water. For the system of alloy Kh17N13M2-H 2 O the section of a E-pH diagram is plotted at 25 deg C [ru

Electron-phonon interaction on an Al(001) surface

International Nuclear Information System (INIS)

Sklyadneva, I Yu; Chulkov, E V; Echenique, P M

2008-01-01

We report an ab initio study of the electron-phonon (e-ph) interaction and its contribution to the lifetime broadening of excited hole (electron) surface states on Al(001). The calculations based on density-functional theory were carried out using a linear response approach in the plane-wave pseudopotential representation. The obtained results show that both the electron-phonon coupling and the linewidth experience a weak variation with the energy and momentum position of a hole (electron) surface state in the energy band. An analysis of different contributions to the e-ph coupling reveals that bulk phonon modes turn out to be more involved in the scattering processes of excited electrons and holes than surface phonon modes. It is also shown that the role of the e-ph coupling in the broadening of the Rayleigh surface phonon mode is insignificant compared to anharmonic effects

Experimental investigation of an actively controlled three-dimensional turret wake

Science.gov (United States)

Shea, Patrick R.

Hemispherical turrets are bluff bodies commonly used to house optical systems on airborne platforms. These bluff bodies develop complex, three-dimensional flow fields that introduce high mean and fluctuating loads to the turret as well as the airframe support structure which reduce the performance of both the optical systems and the aircraft. An experimental investigation of the wake of a three-dimensional, non-conformal turret was performed in a low-speed wind tunnel at Syracuse University to develop a better understanding of the fundamental flow physics associated with the turret wake. The flow field was studied at a diameter based Reynolds number of 550,000 using stereoscopic particle image velocimetry and dynamic pressure measurements both with and without active flow control. Pressure measurements were simultaneously sampled with the PIV measurements and taken on the surrounding boundary layer plate and at several locations on the turret geometry. Active flow control of the turret wake was performed around the leading edge of the turret aperture using dynamic suction in steady open-loop, unsteady open-loop, and simple closed-loop configurations. Analysis of the uncontrolled wake provided insight into the complex three-dimensional wake when evaluated spatially using PIV measurements and temporally using spectral analysis of the pressure measurements. Steady open-loop suction was found to significantly alter the spatial and temporal nature of the turret wake despite the control being applied locally to the aperture region of the turret. Unsteady open-loop and simple closed-loop control were found to provide similar levels of control to the steady open-loop forcing with a 45% reduction in the control input as calculated using the jet momentum coefficient. The data set collected provides unique information regarding the development of the baseline three-dimensional wake and the wake with three different active flow control configurations. These data can be used to

First Test of Fan Active Noise Control (ANC) Completed

Science.gov (United States)

2005-01-01

With the advent of ultrahigh-bypass engines, the space available for passive acoustic treatment is becoming more limited, whereas noise regulations are becoming more stringent. Active noise control (ANC) holds promise as a solution to this problem. It uses secondary (added) noise sources to reduce or eliminate the offending noise radiation. The first active noise control test on the low-speed fan test bed was a General Electric Company system designed to control either the exhaust or inlet fan tone. This system consists of a "ring source," an induct array of error microphones, and a control computer. Fan tone noise propagates in a duct in the form of spinning waves. These waves are detected by the microphone array, and the computer identifies their spinning structure. The computer then controls the "ring source" to generate waves that have the same spinning structure and amplitude, but 180 out of phase with the fan noise. This computer generated tone cancels the fan tone before it radiates from the duct and is heard in the far field. The "ring source" used in these tests is a cylindrical array of 16 flat-plate acoustic radiators that are driven by thin piezoceramic sheets bonded to their back surfaces. The resulting source can produce spinning waves up to mode 7 at levels high enough to cancel the fan tone. The control software is flexible enough to work on spinning mode orders from -6 to 6. In this test, the fan was configured to produce a tone of order 6. The complete modal (spinning and radial) structure of the tones was measured with two builtin sets of rotating microphone rakes. These rakes provide a measurement of the system performance independent from the control system error microphones. In addition, the far-field noise was measured with a semicircular array of 28 microphones. This test represents the first in a series of tests that demonstrate different active noise control concepts, each on a progressively more complicated modal structure. The tests are

A novel technique for active vibration control, based on optimal

Indian Academy of Sciences (India)

In the last few decades, researchers have proposed many control techniques to suppress unwanted vibrations in a structure. In this work, a novel and simple technique is proposed for the active vibration control. In this technique, an optimal tracking control is employed to suppress vibrations in a structure by simultaneously ...

Predictive Duty Cycle Control of Three-Phase Active-Front-End Rectifiers

DEFF Research Database (Denmark)

Song, Zhanfeng; Tian, Yanjun; Chen, Wei

2016-01-01

This paper proposed an on-line optimizing duty cycle control approach for three-phase active-front-end rectifiers, aiming to obtain the optimal control actions under different operating conditions. Similar to finite control set model predictive control strategy, a cost function previously...

Active Queue Management in TCP Networks Based on Fuzzy-Pid Controller

Directory of Open Access Journals (Sweden)

Hossein ASHTIANI

2012-01-01

Full Text Available We introduce a novel and robust active queue management (AQM scheme based on a fuzzy controller, called hybrid fuzzy-PID controller. In the TCP network, AQM is important to regulate the queue length by passing or dropping the packets at the intermediate routers. RED, PI, and PID algorithms have been used for AQM. But these algorithms show weaknesses in the detection and control of congestion under dynamically changing network situations. In this paper a novel Fuzzy-based proportional-integral derivative (PID controller, which acts as an active queue manager (AQM for Internet routers, is proposed. These controllers are used to reduce packet loss and improve network utilization in TCP/IP networks. A new hybrid controller is proposed and compared with traditional RED based controller. Simulations are carried out to demonstrate the effectiveness of the proposed method and show that, the new hybrid fuzzy PID controller provides better performance than random early detection (RED and PID controllers

Active Boundary Layer Control on a Highly Loaded Turbine Exit Case Profile

Directory of Open Access Journals (Sweden)

Julia Kurz

2018-03-01

Full Text Available A highly loaded turbine exit guide vane with active boundary layer control was investigated experimentally in the High Speed Cascade Wind Tunnel at the University of the German Federal Armed Forces, Munich. The experiments include profile Mach number distributions, wake traverse measurements as well as boundary layer investigations with a flattened Pitot probe. Active boundary layer control by fluidic oscillators was applied to achieve improved performance in the low Reynolds number regime. Low solidity, which can be applied to reduce the number of blades, increases the risk of flow separation resulting in increased total pressure losses. Active boundary layer control is supposed to overcome these negative effects. The experiments show that active boundary layer control by fluidic oscillators is an appropriate way to suppress massive open separation bubbles in the low Reynolds number regime.

A Semi-active Control System for Wind Turbines

DEFF Research Database (Denmark)

Caterino, N.; Georgakis, Christos T.; Trinchillo, F.

2014-01-01

A semi-active (SA) control system based on the use of smart magnetorheological (MR) dampers to control the structural response of a wind turbine is proposed herein. The innovative approach is based on the implementation and use of a variable-properties base restraint. This is able to modify in real......, and a control algorithm that instantaneously commands the latter during the motion, making them to modulate the reactive force as needed to achieve the performance goals. The design and operation of such a system are shown with reference to a case study consisting of an almost 100 m tall wind turbine, realized...

Active control of multiple resistive wall modes

International Nuclear Information System (INIS)

Brunsell, P. R.; Yadikin, D.; Gregoratto, D.; Paccagnella, R.; Liu, Y. Q.; Bolzonella, T.; Cecconello, M.; Drake, J. R.; Kuldkepp, M.; Manduchi, G.; Marchiori, G.; Marrelli, L.; Partin, P.; Menmuir, S.; Ortolani, S.; Rachlew, E.; Spizzo, S.; Zanca, P.

2005-01-01

Active magnetic feedback suppression of resistive wall modes is of common interest for several fusion concepts relying on close conducting walls for stabilization of ideal magnetohydrodynamic (MHD) modes. In the advanced tokamak without plasma rotation the kink mode is not completely stabilized, but rather converted into an unstable resistive wall mode (RWM) with a growth time comparable to the wall magnetic flux penetration time. The reversed field pinch (RFP) is similar to the advanced tokamak in the sense that it uses a conducting wall for kink mode stabilization. Also both configurations are susceptible to resonant field error amplification of marginally stable modes. However, the RFP has a different RWM spectrum and, in general, a range of modes is unstable. Hence, the requirement for simultaneous feedback stabilization of multiple independent RWMs arises for the RFP configuration. Recent experiments on RWM feedback stabilization, performed in the RFP device EXTRAP T2R [1], are presented. The experimental results obtained are the first demonstration of simultaneous feedback control of multiple independent RWMs [2]. Using an array of active magnetic coils, a reproducible suppression of several RWMs is achieved for the duration of the discharge, 3-5 wall times, through feedback action. An array with 64 active saddle coils at 4 poloidal times 16 toroidal positions is used. The important issues of side band generation by the active coil array and the accompanying coupling of different unstable modes through the feedback action are addressed in this study. Open loop control experiments have been carried out to quantitatively study resonant field error amplification. (Author)

Hierarchical Active Inference: A Theory of Motivated Control.

Science.gov (United States)

Pezzulo, Giovanni; Rigoli, Francesco; Friston, Karl J

2018-04-01

Motivated control refers to the coordination of behaviour to achieve affectively valenced outcomes or goals. The study of motivated control traditionally assumes a distinction between control and motivational processes, which map to distinct (dorsolateral versus ventromedial) brain systems. However, the respective roles and interactions between these processes remain controversial. We offer a novel perspective that casts control and motivational processes as complementary aspects - goal propagation and prioritization, respectively - of active inference and hierarchical goal processing under deep generative models. We propose that the control hierarchy propagates prior preferences or goals, but their precision is informed by the motivational context, inferred at different levels of the motivational hierarchy. The ensuing integration of control and motivational processes underwrites action and policy selection and, ultimately, motivated behaviour, by enabling deep inference to prioritize goals in a context-sensitive way. Copyright © 2018 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Passive and Active Vibration Control of Renewable Energy Structures

DEFF Research Database (Denmark)

Zhang, Zili

The present thesis deals with fundamental researches on passive and active vibration control of renewable energy structures, and provides useful models for practical applications. Effective and robust vibration control methods have been explored for mitigating the lightly damped edgewise blade...... solutions for wave energy point absorbers, in order to maximize the mean absorbed power and to deliver more smooth power to the grid. A novel suboptimal causal control law has been established for controlling the motion of the point absorber, and a new type of point absorber has also been proposed...

Controller modification applied for active fault detection

DEFF Research Database (Denmark)

Niemann, Hans Henrik; Stoustrup, Jakob; Poulsen, Niels Kjølstad

2014-01-01

This paper is focusing on active fault detection (AFD) for parametric faults in closed-loop systems. This auxiliary input applied for the fault detection will also disturb the external output and consequently reduce the performance of the controller. Therefore, only small auxiliary inputs are used...... with the result that the detection and isolation time can be long. In this paper it will be shown, that this problem can be handled by using a modification of the feedback controller. By applying the YJBK-parameterization (after Youla, Jabr, Bongiorno and Kucera) for the controller, it is possible to modify...... the frequency for the auxiliary input is selected. This gives that it is possible to apply an auxiliary input with a reduced amplitude. An example is included to show the results....

Adaptive piezoelectric sensoriactuators for active structural acoustic control

Science.gov (United States)

Vipperman, Jeffrey Stuart

1997-09-01

A new transducer technology with application to active control systems, modal analysis, and autonomous system health monitoring, is brought to fruition in this work. It has the advantages of being lightweight, potentially cost-effective, self-tuning, has negligible dynamics, and most importantly (from a robustness perspective), it provides a colocated sensor/actuator pair. The transducer consists of a piezoceramic element which serves as both an actuator and a sensor and will be referred to in this work as a sensoriactuator. Simple, adaptive signal processing in conjunction with a voltage controlled amplifier, reference capacitor, and a common-mode rejection circuit extract the mechanical response from the total response of the piezoelectric sensoriactuator for sensing. The digital portion of the adaptive piezoelectric sensoriactuator merely serves to tune the circuit, avoiding the potentially destabilizing effects of introducing a digital delay in the signal path, when used for feedback control applications. Adaptive compensation of the sensoriactuator is necessary since the signal to noise ratio is typically greater than 40 dB, making it prohibitive to tune the circuit manually. In addition, the constitutive properties of piezoceramics vary with time and environment, necessitating that the circuit be periodically re-tuned. The analog portion of the hardware is based upon op-amp circuits and an AD632 analog multiplier chip, which serves as both a voltage controlled amplifier (VCA) and a common mode rejection (CMR) circuit. A single coefficient least-mean square (LMS) adaptive filter continuously adjusts the gain of the VCA circuit as necessary. Nonideal behavior of piezoceramics is discussed along with methods to counter the consequential deterioration in circuit performance. A multiple input multiple output (MIMO) implementation of the adaptive piezoelectric sensoriactuator is developed using orthogonal white noise training signals for each sensoriactuator. Two

Power system damping - Structural aspects of controlling active power

Energy Technology Data Exchange (ETDEWEB)

Samuelsson, O.

1997-04-01

Environmental and economical aspects make it difficult to build new power lines and to reinforce existing ones. The continued growth in demand for electric power must therefore to a great extent be met by increased loading of available lines. A consequence is that power system damping is reduced, leading to a risk of poorly damped power oscillations between the generators. This thesis proposes the use of controlled active loads to increase damping of such electro-mechanical oscillations. The focus is on structural aspects of controller interaction and of sensor and actuator placement. On-off control based on machine frequency in a single machine infinite bus system is analysed using energy function analysis and phase plane plots. An on-off controller with estimated machine frequency as input has been implemented. At a field test it damped oscillations of a 0.9 MW hydro power generator by controlling a 20kW load. The linear analysis uses two power system models with three and twenty-three machines respectively. Each damper has active power as output and local bus frequency or machine frequency as input. The power system simulator EUROSTAG is used both for generation of the linearized models and for time simulations. Measures of active power mode controllability and phase angle mode observability are obtained from the eigenvectors of the differential-algebraic models. The geographical variation in the network of these quantities is illustrated using the resemblance to bending modes of flexible mechanical structures. Eigenvalue sensitivities are used to determine suitable damper locations. A spring-mass equivalent to an inter-area mode provides analytical expressions, that together with the concept of impedance matching explain the structural behaviour of the power systems. For large gains this is investigated using root locus plots. 64 refs, 99 figs, 20 tabs

Control of chaotic oscillators via a class of model free active controller: Suppresion and synchronization

Energy Technology Data Exchange (ETDEWEB)

Aguilar-Lopez, Ricardo [Division de Ciencias Basicas e Ingenieria, Universidad Autonoma Metropolitana, Av. San Pablo No. 180, Reynosa-Tamaulipas, 02200, Azcapotzalco, Mexico D.F. (Mexico)], E-mail: raguilar@correo.azc.uam.mx; Martinez-Guerra, Rafael [Departamento de Control Automatico, CINVESTAV-IPN, Apartado Postal 14-740, 07360 Mexico D.F. (Mexico)], E-mail: rguerra@ctrl.cinvestav.mx

2008-10-15

The goal of this work is related with the control of chaotic oscillators for chaos suppression and synchronization purposes. The proposed methodology is related with a class of robust active control (RAC) law, where the stabilizing part of the control structure is related with an integral high order sliding-mode and proportional form of the so-called control error. The proposed controller is applied to chaos suppression, synchronization and anti-synchronization tasks for nonlinear oscillators with different order and structure. Numerical experiments illustrate the satisfactory performance of the proposed methodology, when it is applied to Duffing and Chen oscillators.

Control of chaotic oscillators via a class of model free active controller: Suppresion and synchronization

International Nuclear Information System (INIS)

Aguilar-Lopez, Ricardo; Martinez-Guerra, Rafael

2008-01-01

The goal of this work is related with the control of chaotic oscillators for chaos suppression and synchronization purposes. The proposed methodology is related with a class of robust active control (RAC) law, where the stabilizing part of the control structure is related with an integral high order sliding-mode and proportional form of the so-called control error. The proposed controller is applied to chaos suppression, synchronization and anti-synchronization tasks for nonlinear oscillators with different order and structure. Numerical experiments illustrate the satisfactory performance of the proposed methodology, when it is applied to Duffing and Chen oscillators

Active transportation in adult survivors of childhood cancer and neighborhood controls.

Science.gov (United States)

Slater, Megan E; Kelly, Aaron S; Sadak, Karim T; Ross, Julie A

2016-02-01

Childhood cancer survivors (CCS) are at high risk of treatment-related late effects, including cardiovascular disease and diabetes, which can be exacerbated by inadequate physical activity (PA). Previous PA interventions targeting CCS have focused on the domain of leisure-time/recreational PA. Active transportation, another domain of PA, has not been described in CCS. Therefore, this study aimed to identify active transportation behaviors, barriers, and correlates in adult CCS. We recruited 158 adult CCS and 153 controls matched on age, sex, and neighborhood for a survey regarding active transportation behaviors and perceptions. Linear and logistic regression models accounting for correlation among matched participants were used. Adult CCS engaged in similar levels of active transportation as controls (2.72 vs. 2.32 h/week, P = 0.40) despite perceiving greater health-related barriers (1.88 vs. 1.65 (measured on four-point Likert scale), P = 0.01). Marital/relationship status (odds ratio (OR) = 0.30, 95 % confidence interval (CI) = 0.11-0.81), planning/psychosocial barriers (OR = 0.15, 95 % CI = 0.04-0.53), and perceived neighborhood walkability (OR = 2.55, 95 % CI = 1.14-5.66) were correlates of active transportation among adult CCS, while objective neighborhood walkability (OR = 1.03, 95 % CI = 1.01-1.05) was a correlate among controls. Results suggest adult CCS and controls utilize active transportation at approximately equal levels. Factors other than health, including perceived neighborhood walkability, are related to active transportation behaviors to a greater degree in adult CCS. Interventions might consider promoting active transportation as a way to incorporate more PA into the daily lives of adult CCS. Such interventions will not be likely successful, however, without existing or improved neighborhood walkability/bikeability.

Active Transportation in Adult Survivors of Childhood Cancer and Neighborhood Controls

Science.gov (United States)

Slater, Megan E.; Kelly, Aaron S.; Sadak, Karim T.; Ross, Julie A.

2015-01-01

Purpose Childhood cancer survivors (CCS) are at high risk of treatment-related late effects, including cardiovascular disease and diabetes, which can be exacerbated by inadequate physical activity (PA). Previous PA interventions targeting CCS have focused on the domain of leisure-time/recreational PA. Active transportation, another domain of PA, has not been described in CCS. Therefore, this study aimed to identify active transportation behaviors, barriers, and correlates in adult CCS. Methods We recruited 158 adult CCS and 153 controls matched on age, sex, and neighborhood for a survey regarding active transportation behaviors and perceptions. Linear and logistic regression models accounting for correlation among matched participants were used. Results Adult CCS engaged in similar levels of active transportation as controls (2.72 vs. 2.32 hours/week, P=0.40) despite perceiving greater health-related barriers (1.88 vs. 1.65 (measured on four-point Likert scale), P=0.01). Marital/relationship status (odds ratio (OR)=0.30, 95% confidence interval (CI)=0.11–0.81), planning/psychosocial barriers (OR=0.15, 95% CI=0.04–0.53), and perceived neighborhood walkability (OR=2.55, 95% CI=1.14–5.66) were correlates of active transportation among adult CCS, while objective neighborhood walkability (OR=1.03, 95% CI=1.01–1.05) was a correlate among controls. Conclusions Results suggest adult CCS and controls utilize active transportation at approximately equal levels. Factors other than health, including perceived neighborhood walkability, appear to influence active transportation behaviors to a greater degree in adult CCS. Implications for Cancer Survivors Interventions might consider promoting active transportation as a way to incorporate more PA into the daily lives of adult CCS. Such interventions will not be widely successful, however, without existing or improved neighborhood walkability/bikeability. PMID:25809159

Active Power Control of Waked Wind Farms: Preprint

Energy Technology Data Exchange (ETDEWEB)

Fleming, Paul A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); van Wingerden, Jan-Willem [Delft University of Technology; Pao, Lucy [University of Colorado; Aho, Jacob [University of Colorado

2017-08-15

Active power control can be used to balance the total power generated by wind farms with the power consumed on the electricity grid. With the increasing penetration levels of wind energy, there is an increasing need for this ancillary service. In this paper, we show that the tracking of a certain power reference signal provided by the transmission system operator can be significantly improved by using feedback control at the wind farm level. We propose a simple feedback control law that significantly improves the tracking behavior of the total power output of the farm, resulting in higher performance scores. The effectiveness of the proposed feedback controller is demonstrated using high-fidelity computational fluid dynamics simulations of a small wind farm.

Hilar GABAergic interneuron activity controls spatial learning and memory retrieval.

Directory of Open Access Journals (Sweden)

Yaisa Andrews-Zwilling

Full Text Available Although extensive research has demonstrated the importance of excitatory granule neurons in the dentate gyrus of the hippocampus in normal learning and memory and in the pathogenesis of amnesia in Alzheimer's disease (AD, the role of hilar GABAergic inhibitory interneurons, which control the granule neuron activity, remains unclear.We explored the function of hilar GABAergic interneurons in spatial learning and memory by inhibiting their activity through Cre-dependent viral expression of enhanced halorhodopsin (eNpHR3.0--a light-driven chloride pump. Hilar GABAergic interneuron-specific expression of eNpHR3.0 was achieved by bilaterally injecting adeno-associated virus containing a double-floxed inverted open-reading frame encoding eNpHR3.0 into the hilus of the dentate gyrus of mice expressing Cre recombinase under the control of an enhancer specific for GABAergic interneurons. In vitro and in vivo illumination with a yellow laser elicited inhibition of hilar GABAergic interneurons and consequent activation of dentate granule neurons, without affecting pyramidal neurons in the CA3 and CA1 regions of the hippocampus. We found that optogenetic inhibition of hilar GABAergic interneuron activity impaired spatial learning and memory retrieval, without affecting memory retention, as determined in the Morris water maze test. Importantly, optogenetic inhibition of hilar GABAergic interneuron activity did not alter short-term working memory, motor coordination, or exploratory activity.Our findings establish a critical role for hilar GABAergic interneuron activity in controlling spatial learning and memory retrieval and provide evidence for the potential contribution of GABAergic interneuron impairment to the pathogenesis of amnesia in AD.

Generalized internal model robust control for active front steering intervention

Science.gov (United States)

Wu, Jian; Zhao, Youqun; Ji, Xuewu; Liu, Yahui; Zhang, Lipeng

2015-03-01

Because of the tire nonlinearity and vehicle's parameters' uncertainties, robust control methods based on the worst cases, such as H ∞, µ synthesis, have been widely used in active front steering control, however, in order to guarantee the stability of active front steering system (AFS) controller, the robust control is at the cost of performance so that the robust controller is a little conservative and has low performance for AFS control. In this paper, a generalized internal model robust control (GIMC) that can overcome the contradiction between performance and stability is used in the AFS control. In GIMC, the Youla parameterization is used in an improved way. And GIMC controller includes two sections: a high performance controller designed for the nominal vehicle model and a robust controller compensating the vehicle parameters' uncertainties and some external disturbances. Simulations of double lane change (DLC) maneuver and that of braking on split- µ road are conducted to compare the performance and stability of the GIMC control, the nominal performance PID controller and the H ∞ controller. Simulation results show that the high nominal performance PID controller will be unstable under some extreme situations because of large vehicle's parameters variations, H ∞ controller is conservative so that the performance is a little low, and only the GIMC controller overcomes the contradiction between performance and robustness, which can both ensure the stability of the AFS controller and guarantee the high performance of the AFS controller. Therefore, the GIMC method proposed for AFS can overcome some disadvantages of control methods used by current AFS system, that is, can solve the instability of PID or LQP control methods and the low performance of the standard H ∞ controller.

Active vibration control of smart hull structure using piezoelectric composite actuators

International Nuclear Information System (INIS)

Sohn, Jung Woo; Choi, Seung-Bok; Lee, Chul-Hee

2009-01-01

In this paper, active vibration control performance of the smart hull structure with macro-fiber composite (MFC) is evaluated. MFC is an advanced piezoelectric composite which has great flexibility and increased actuating performance compared to a monolithic piezoelectric ceramic patch. The governing equations of motion of the hull structure with MFC actuators are derived based on the classical Donnell–Mushtari shell theory. The actuating model for the interaction between hull structure and MFC is included in the governing equations. Subsequently, modal characteristics are investigated and compared with the results obtained from experiment. The governing equations of the vibration control system are then established and expressed in the state space form. A linear quadratic Gaussian (LQG) control algorithm is designed in order to effectively and actively control the imposed vibration. The controller is experimentally realized and vibration control performances are evaluated

Adaptive and robust active vibration control methodology and tests

CERN Document Server

Landau, Ioan Doré; Castellanos-Silva, Abraham; Constantinescu, Aurelian

2017-01-01

This book approaches the design of active vibration control systems from the perspective of today’s ideas of computer control. It formulates the various design problems encountered in the active management of vibration as control problems and searches for the most appropriate tools to solve them. The experimental validation of the solutions proposed on relevant tests benches is also addressed. To promote the widespread acceptance of these techniques, the presentation eliminates unnecessary theoretical developments (which can be found elsewhere) and focuses on algorithms and their use. The solutions proposed cannot be fully understood and creatively exploited without a clear understanding of the basic concepts and methods, so these are considered in depth. The focus is on enhancing motivations, algorithm presentation and experimental evaluation. MATLAB®routines, Simulink® diagrams and bench-test data are available for download and encourage easy assimilation of the experimental and exemplary material. Thre...

Elastomer Nanocomposites Based on Butadiene Rubber, Nanoclay and Epoxy-Polyester Hybrid: Microstructure and Mechanical Properties

OpenAIRE

Sepideh Zoghi; Ghasem Naderi; Gholam Reza Bakhshandeh; Morteza Ehsani; Shirin Shokoohi

2013-01-01

Nanocomposites based on butadiene rubber (BR), (0, 3, 5 and 7 phr) organoclay (Cloisite 15A) and (0, 10, 20, 30, 40 phr) powder coating wastes, i.e., epoxypolyester hybrid (EPH) were prepared using a laboratory-scale internal mixer in order to study the effect of organoclay and EPH content on the mechanical and morphological properties of the nanocomposite samples. Cure characteristics of the prepared compounds including optimum cure time (t90) and scorch time (t5) depicted a decrease in both...

Resonant passive–active vibration absorber with integrated force feedback control

International Nuclear Information System (INIS)

Høgsberg, Jan; Brodersen, Mark L; Krenk, Steen

2016-01-01

A general format of a two-terminal vibration absorber is constructed by placing a passive unit in series with a hybrid unit, composed of an active actuator in parallel with a second passive element. The displacement of the active actuator is controlled by an integrated feedback control with the difference in force between the two passive elements as input. This format allows passive and active contributions to be combined arbitrarily within the hybrid unit, which results in a versatile absorber format with guaranteed closed-loop stability. This is demonstrated for resonant absorbers with inertia realized passively by a mechanical inerter or actively by the integrated force feedback. Accurate calibration formulae are presented for two particular absorber configurations and the performance is subsequently demonstrated with respect to both equal modal damping and effective response reduction. (technical note)

Active queue management controller design for TCP communication networks: Variable structure control approach

International Nuclear Information System (INIS)

Chen, C.-K.; Liao, T.-L.; Yan, J.-J.

2009-01-01

On the basis of variable structure control (VSC), an active queue management (AQM) controller is presented for a class of TCP communication networks. In the TCP/IP networks, the packet drop probability is limited between 0 and 1. Therefore, we modeled TCP/AQM as a rate-based non-linear system with a saturated input. The objective of the VSC-based AQM controller is to achieve the desired queue size and to guarantee the asymptotic stability of the closed-loop TCP non-linear system with saturated input. The performance and effectiveness of the proposed control law are then validated for different network scenarios through numerical simulations in both MATLAB and Network Simulator-2 (NS-2). Both sets of simulation results have confirmed that the proposed scheme outperforms other AQM schemes.

Active queue management controller design for TCP communication networks: Variable structure control approach

Energy Technology Data Exchange (ETDEWEB)

Chen, C.-K. [Department of Engineering Science, National Cheng Kung University, Tainan 701, Taiwan (China); Liao, T.-L. [Department of Engineering Science, National Cheng Kung University, Tainan 701, Taiwan (China)], E-mail: tlliao@mail.ncku.edu; Yan, J.-J. [Department of Computer and Communication, Shu-Te University, Kaohsiung 824, Taiwan (China)

2009-04-15

On the basis of variable structure control (VSC), an active queue management (AQM) controller is presented for a class of TCP communication networks. In the TCP/IP networks, the packet drop probability is limited between 0 and 1. Therefore, we modeled TCP/AQM as a rate-based non-linear system with a saturated input. The objective of the VSC-based AQM controller is to achieve the desired queue size and to guarantee the asymptotic stability of the closed-loop TCP non-linear system with saturated input. The performance and effectiveness of the proposed control law are then validated for different network scenarios through numerical simulations in both MATLAB and Network Simulator-2 (NS-2). Both sets of simulation results have confirmed that the proposed scheme outperforms other AQM schemes.

Tuningless Load Frequency Control Through Active Engagement of Distributed Resources

DEFF Research Database (Denmark)

Prostejovsky, Alexander; Marinelli, Mattia; Rezkalla, Michel M.N.

2017-01-01

system dynamics. Second, primary resources are actively involved in frequency restoration by systematic adjustment of their frequency reference setpoints. In contrast to the commonly used Automatic Generation Control (AGC), the proposed Direct Load Frequency Control (DLFC) does not require an integrator...

Smart Materials and Active Noise and Vibration Control in Vehicles

NARCIS (Netherlands)

Doppenberg, E.J.J.; Berkhoff, Arthur P.; van Overbeek, M.; Gissinger, G.L.

2001-01-01

The paper presents the results for the reduction of sound radiated from a structure using different control methodologies, and discusses two approaches for active structural acoustic control: the acoustic approach or the vibro-acoustic approach. Integrated actuators in structure material are

Chronophin coordinates cell leading edge dynamics by controlling active cofilin levels

Science.gov (United States)

Delorme-Walker, Violaine; Seo, Ji-Yeon; Gohla, Antje; Fowler, Bruce; Bohl, Ben; DerMardirossian, Céline

2015-01-01

Cofilin, a critical player of actin dynamics, is spatially and temporally regulated to control the direction and force of membrane extension required for cell locomotion. In carcinoma cells, although the signaling pathways regulating cofilin activity to control cell direction have been established, the molecular machinery required to generate the force of the protrusion remains unclear. We show that the cofilin phosphatase chronophin (CIN) spatiotemporally regulates cofilin activity at the cell edge to generate persistent membrane extension. We show that CIN translocates to the leading edge in a PI3-kinase–, Rac1-, and cofilin-dependent manner after EGF stimulation to activate cofilin, promotes actin free barbed end formation, accelerates actin turnover, and enhances membrane protrusion. In addition, we establish that CIN is crucial for the balance of protrusion/retraction events during cell migration. Thus, CIN coordinates the leading edge dynamics by controlling active cofilin levels to promote MTLn3 cell protrusion. PMID:26324884

Multi-level Control Framework for Enhanced Flexibility of Active Distribution Network

DEFF Research Database (Denmark)

Nainar, Karthikeyan; Pokhrel, Basanta Raj; Pillai, Jayakrishnan Radhakrishna

2017-01-01

In this paper, the control objectives of future active distribution networks with high penetration of renewables and flexible loads are analyzed and reviewed. From a state of the art review, the important control objectives seen from the perspective of a distribution system operator are identifie......-ordination and management of the network assets at different voltage levels and geographical locations. The paper finally shows the applicability of the multi-level control architecture to some of the key challenges in the distribution system operation by relevant scenarios....... to be hosting capacity improvement, high reliable operation and cost effective network management. Based on this review and a state of the art review concerning future distribution network control methods, a multi-level control architecture is constructed for an active distribution network, which satisfies...... the selected control objectives and provides enhanced flexibility. The control architecture is supported by generation/load forecasting and distribution state estimation techniques to improve the controllability of the network. The multi-level control architecture consists of three levels of hierarchical...

Leisure-time physical activity patterns by weight control status: 1999-2002 NHANES.

Science.gov (United States)

Kruger, Judy; Yore, Michelle M; Kohl, Harold W

2007-05-01

Regular physical activity reduces the risk of hypertension, type 2 diabetes, coronary heart disease, stroke, and some cancers. Physical activity is associated inversely with overweight and obesity prevalence, thus potentially assisting in weight control efforts. The purpose of this paper is to examine the variability of physical activity levels and their patterns by self-reported weight control status in a nationally representative sample. Four years of data from the 1999-2002 National Health and Nutrition Examination Survey (NHANES) were used to examine leisure-time physical activity patterns (regular, irregular, inactive) and the prevalence of weight control practices (trying to lose, trying to maintain, not trying to lose or maintain) among U.S. adults (N = 9496). The prevalence of regular physical activity was 32.6% among people trying to lose weight, 37.9% among people trying to maintain weight, and 21.8% among those not trying to lose or maintain weight. Those trying to lose weight were almost three times as likely to be regularly active (vs inactive), and those trying to maintain weight were over three times more likely to be regularly active (vs inactive) than those not trying to lose or maintain weight. The most commonly reported activities among those trying to lose weight were walking (38.3%), yard work (14.5%), biking (12.5%), and running (11.6%). Despite the importance of physical activity, fewer than half the people trying to lose or maintain weight were regularly active during leisure-time. People trying to lose or maintain weight had a higher likelihood of being regularly active than those not trying to lose or maintain weight. Walking was the most common type of physical activity among all weight control groups. Health promotion efforts should promote increased levels of physical activity among all adults.

Coordinated Voltage Control of Active Distribution Network

Directory of Open Access Journals (Sweden)

Xie Jiang

2016-01-01

Full Text Available This paper presents a centralized coordinated voltage control method for active distribution network to solve off-limit problem of voltage after incorporation of distributed generation (DG. The proposed method consists of two parts, it coordinated primal-dual interior point method-based voltage regulation schemes of DG reactive powers and capacitors with centralized on-load tap changer (OLTC controlling method which utilizes system’s maximum and minimum voltages, to improve the qualified rate of voltage and reduce the operation numbers of OLTC. The proposed coordination has considered the cost of capacitors. The method is tested using a radial edited IEEE-33 nodes distribution network which is modelled using MATLAB.

A new approach of active compliance control via fuzzy logic control for multifingered robot hand

Science.gov (United States)

Jamil, M. F. A.; Jalani, J.; Ahmad, A.

2016-07-01

Safety is a vital issue in Human-Robot Interaction (HRI). In order to guarantee safety in HRI, a model reference impedance control can be a very useful approach introducing a compliant control. In particular, this paper establishes a fuzzy logic compliance control (i.e. active compliance control) to reduce impact and forces during physical interaction between humans/objects and robots. Exploiting a virtual mass-spring-damper system allows us to determine a desired compliant level by understanding the behavior of the model reference impedance control. The performance of fuzzy logic compliant control is tested in simulation for a robotic hand known as the RED Hand. The results show that the fuzzy logic is a feasible control approach, particularly to control position and to provide compliant control. In addition, the fuzzy logic control allows us to simplify the controller design process (i.e. avoid complex computation) when dealing with nonlinearities and uncertainties.

Very low speed performance of active flux based sensorless control: interior permanent magnet synchronous motor vector control versus direct torque and flux control

DEFF Research Database (Denmark)

Paicu, M. C.; Boldea, I.; Andreescu, G. D.

2009-01-01

This study is focused on very low speed performance comparison between two sensorless control systems based on the novel ‘active flux' concept, that is, the current/voltage vector control versus direct torque and flux control (DTFC) for interior permanent magnet synchronous motor (IPMSM) drives...... with space vector modulation (SVM), without signal injection. The active flux, defined as the flux that multiplies iq current in the dq-model torque expression of all ac machines, is easily obtained from the stator-flux vector and has the rotor position orientation. Therefore notable simplification...

Usefulness of charge-transfer complexation for the assessment of sympathomimetic drugs: Spectroscopic properties of drug ephedrine hydrochloride complexed with some π-acceptors

Science.gov (United States)

Refat, Moamen S.; Ibrahim, Omar B.; Saad, Hosam A.; Adam, Abdel Majid A.

2014-05-01

Recently, ephedrine (Eph) assessment in food products, pharmaceutical formulations, human fluids of athletes and detection of drug toxicity and abuse, has gained a growing interest. To provide basic data that can be used to assessment of Eph quantitatively based on charge-transfer (CT) complexation, the CT complexes of Eph with 7‧,8,8‧-tetracyanoquinodimethane (TCNQ), dichlorodicyanobenzoquinone (DDQ), 1,3-dinitrobenzene (DNB) or tetrabromothiophene (TBT) were synthesized and spectroscopically investigated. The newly synthesized complexes have been characterized via elemental analysis, IR, Raman, 1H NMR, and UV-visible spectroscopy. The formation constant (KCT), molar extinction coefficient (εCT) and other spectroscopic data have been determined using the Benesi-Hildebrand method and its modifications. The sharp, well-defined Bragg reflections at specific 2θ angles have been identified from the powder X-ray diffraction patterns. Thermal decomposition behavior of these complexes was also studied, and their kinetic thermodynamic parameters were calculated with Coats-Redfern and Horowitz-Metzger equations.

Serum protein electrophoresis values for free-ranging and zoo-based koalas (Phascolarctos cinereus).

Science.gov (United States)

Pye, Geoffrey W; Ellis, William; Fitzgibbon, Sean; Opitz, Brian; Keener, Laura; Arheart, Kristopher L; Cray, Carolyn

2012-03-01

In a clinical setting, especially with species of special interest, it is important to use all clinical pathology testing options for general health monitoring and diagnosis. Protein electrophoresis (EPH) has previously been shown to be an important adjunct tool in veterinary medicine. Serum samples from 18 free-ranging and 12 zoo-based koalas (Phascolarctos cinereus) were subject to EPH analysis. Significant differences were found between the two groups for the following values: total protein, albumin, beta globulins, and albumin-globulin ratio (P < 0.05). By using the combined data, the minimum-maximum values for the EPH fractions were as follows: total protein 5.0-7.8 g/dl, albumin 2.8-4.7 g/dl, alpha-1 globulins 0.5-1.1 g/dl, alpha-2 globulins 0.3-0.7 g/dl, beta globulins 0.4-1.0 g/dl, gamma globulins 0.2-1.0 g/dl, and albumin-globulin ratio 1.0-2.1.

Improving Accuracy of Processing Through Active Control

Directory of Open Access Journals (Sweden)

N. N. Barbashov

2016-01-01

Full Text Available An important task of modern mathematical statistics with its methods based on the theory of probability is a scientific estimate of measurement results. There are certain costs under control, and under ineffective control when a customer has got defective products these costs are significantly higher because of parts recall.When machining the parts, under the influence of errors a range scatter of part dimensions is offset towards the tolerance limit. To improve a processing accuracy and avoid defective products involves reducing components of error in machining, i.e. to improve the accuracy of machine and tool, tool life, rigidity of the system, accuracy of the adjustment. In a given time it is also necessary to adapt machine.To improve an accuracy and a machining rate there, currently  become extensively popular various the in-process gaging devices and controlled machining that uses adaptive control systems for the process monitoring. Improving the accuracy in this case is compensation of a majority of technological errors. The in-cycle measuring sensors (sensors of active control allow processing accuracy improvement by one or two quality and provide a capability for simultaneous operation of several machines.Efficient use of in-cycle measuring sensors requires development of methods to control the accuracy through providing the appropriate adjustments. Methods based on the moving average, appear to be the most promising for accuracy control since they include data on the change in some last measured values of the parameter under control.

Short Horizon Control Strategies for an Alternating Activated Sludge Process

DEFF Research Database (Denmark)

Isaacs, Steven Howard

1996-01-01

Three control strategies allowing improved operational flexibility of an alternating type activated sludge process are presented in a unified model based framework. The control handles employed are the addition rate of an external carbon source to denitrification, the cycle length, and the dissol...

Hierarchical Control Strategy for Active Hydropneumatic Suspension Vehicles Based on Genetic Algorithms

Directory of Open Access Journals (Sweden)

Jinzhi Feng

2015-02-01

Full Text Available A new hierarchical control strategy for active hydropneumatic suspension systems is proposed. This strategy considers the dynamic characteristics of the actuator. The top hierarchy controller uses a combined control scheme: a genetic algorithm- (GA- based self-tuning proportional-integral-derivative controller and a fuzzy logic controller. For practical implementations of the proposed control scheme, a GA-based self-learning process is initiated only when the defined performance index of vehicle dynamics exceeds a certain debounce time threshold. The designed control algorithm is implemented on a virtual prototype and cosimulations are performed with different road disturbance inputs. Cosimulation results show that the active hydropneumatic suspension system designed in this study significantly improves riding comfort characteristics of vehicles. The robustness and adaptability of the proposed controller are also examined when the control system is subjected to extremely rough road conditions.

Regulatory control of maintenance activities in Argentine nuclear power plants

International Nuclear Information System (INIS)

Calvo, J.C.; Caruso, G.

2000-01-01

The main maintenance objective is to assure that the safety features of structures, components and systems of nuclear power plants are kept as designed. Therefore, there is a direct relationship between safety and maintenance. Owing to the above mentioned, maintenance activities are considered a relevant regulatory issue for the Argentine Nuclear Regulatory Authority (ARN). This paper describes the regulatory control to maintenance activities of Argentine nuclear power plants. It also addresses essential elements for maintenance control, routine inspections, special inspections during planned outages, audits and license conditions and requirements. (author)

Control of Surge in Centrifugal Compressors by Active Magnetic Bearings Theory and Implementation

CERN Document Server

Yoon, Se Young; Allaire, Paul E

2013-01-01

Control of Surge in Centrifugal Compressors by Active Magnetic Bearings sets out the fundamentals of integrating the active magnetic bearing (AMB) rotor suspension technology in compressor systems, and describes how this relatively new bearing technology can be employed in the active control of compressor surge. The authors provide a self-contained and comprehensive review of rotordynamics and the fundamentals of the AMB technology. The active stabilization of compressor surge employing AMBs in a machine is fully explored, from the modeling of the instability and the design of feedback controllers, to the implementation and experimental testing of the control algorithms in a specially-constructed, industrial-size centrifugal compression system. The results of these tests demonstrate the great potential of the new surge control method developed in this text. This book will be useful for engineers in industries that involve turbocompressors and magnetic bearings, as well as for researchers and graduate students...

Disturbance observer based Takagi-Sugeno fuzzy control for an active seat suspension

Science.gov (United States)

Ning, Donghong; Sun, Shuaishuai; Zhang, Fei; Du, Haiping; Li, Weihua; Zhang, Bangji

2017-09-01

In this paper, a disturbance observer based Takagi-Sugeno (TS) fuzzy controller is proposed for an active seat suspension; both simulations and experiments have been performed verifying the performance enhancement and stability of the proposed controller. The controller incorporates closed-loop feedback control using the measured acceleration of the seat and deflection of the suspension; these two variables can be easily measured in practical applications, thus allowing the proposed controller to be robust and adaptable. A disturbance observer that can estimate the disturbance caused by friction, model simplification, and controller output error has also been used to compensate a H∞ state feedback controller. The TS fuzzy control method is applied to enhance the controller's performance by considering the variation of driver's weight during operation. The vibration of a heavy duty vehicle seat is largest in the frequency range between 2 Hz and 4 Hz, in the vertical direction; therefore, it is reasonable to focus on controlling low frequency vibration amplitudes and maintain the seat suspensions passivity at high frequency. Moreover, both the simulation and experimental results show that the active seat suspension with the proposed controller can effectively isolate unwanted vibration amplitudes below 4.5 Hz, when compared with a well-tuned passive seat suspension. The active controller has been further validated under bump and random road tests with both a 55 kg and a 70 kg loads. The bump road test demonstrated the controller has good transient response capabilities. The random road test result has been presented both in the time domain and the frequency domain. When with the above two loads, the controlled seat suspensions root-mean-square (RMS) accelerations were reduced by 45.5% and 49.5%, respectively, compared with a well-tuned passive seat suspension. The proposed active seat suspension controller has great potential and is very practical for application

Hilar GABAergic Interneuron Activity Controls Spatial Learning and Memory Retrieval

Science.gov (United States)

Andrews-Zwilling, Yaisa; Gillespie, Anna K.; Kravitz, Alexxai V.; Nelson, Alexandra B.; Devidze, Nino; Lo, Iris; Yoon, Seo Yeon; Bien-Ly, Nga; Ring, Karen; Zwilling, Daniel; Potter, Gregory B.; Rubenstein, John L. R.; Kreitzer, Anatol C.; Huang, Yadong

2012-01-01

Background Although extensive research has demonstrated the importance of excitatory granule neurons in the dentate gyrus of the hippocampus in normal learning and memory and in the pathogenesis of amnesia in Alzheimer's disease (AD), the role of hilar GABAergic inhibitory interneurons, which control the granule neuron activity, remains unclear. Methodology and Principal Findings We explored the function of hilar GABAergic interneurons in spatial learning and memory by inhibiting their activity through Cre-dependent viral expression of enhanced halorhodopsin (eNpHR3.0)—a light-driven chloride pump. Hilar GABAergic interneuron-specific expression of eNpHR3.0 was achieved by bilaterally injecting adeno-associated virus containing a double-floxed inverted open-reading frame encoding eNpHR3.0 into the hilus of the dentate gyrus of mice expressing Cre recombinase under the control of an enhancer specific for GABAergic interneurons. In vitro and in vivo illumination with a yellow laser elicited inhibition of hilar GABAergic interneurons and consequent activation of dentate granule neurons, without affecting pyramidal neurons in the CA3 and CA1 regions of the hippocampus. We found that optogenetic inhibition of hilar GABAergic interneuron activity impaired spatial learning and memory retrieval, without affecting memory retention, as determined in the Morris water maze test. Importantly, optogenetic inhibition of hilar GABAergic interneuron activity did not alter short-term working memory, motor coordination, or exploratory activity. Conclusions and Significance Our findings establish a critical role for hilar GABAergic interneuron activity in controlling spatial learning and memory retrieval and provide evidence for the potential contribution of GABAergic interneuron impairment to the pathogenesis of amnesia in AD. PMID:22792368

Antral atrophy, intestinal metaplasia, and preneoplastic markers in Mexican children with Helicobacter pylori-positive and Helicobacter pylori-negative gastritis.

Science.gov (United States)

Villarreal-Calderon, Rodolfo; Luévano-González, Arturo; Aragón-Flores, Mariana; Zhu, Hongtu; Yuan, Ying; Xiang, Qun; Yan, Benjamin; Stoll, Kathryn Anne; Cross, Janet V; Iczkowski, Kenneth A; Mackinnon, Alexander Craig

2014-06-01

Chronic inflammation and infection are major risk factors for gastric carcinogenesis in adults. As chronic gastritis is common in Mexican children, diagnosis of Helicobacter pylori and other causes of gastritis are critical for the identification of children who would benefit from closer surveillance. Antral biopsies from 82 Mexican children (mean age, 8.3 ± 4.8 years) with chronic gastritis (36 H pylori+, 46 H pylori-) were examined for gastritis activity, atrophy, intestinal metaplasia (IM), and immunohistochemical expression of gastric carcinogenesis biomarkers caudal type homeobox 2 (CDX2), ephrin type-B receptor 4 (EphB4), matrix metalloproteinase 3 (MMP3), macrophage migration inhibitory factor (MIF), p53, β-catenin, and E-cadherin. Atrophy was diagnosed in 7 (9%) of 82, and IM, in 5 (6%) of 82 by routine histology, whereas 6 additional children (7%) (3 H pylori+) exhibited aberrant CDX2 expression without IM. Significant positive correlations were seen between EphB4, MMP3, and MIF (Pgastritis. Copyright © 2014 Elsevier Inc. All rights reserved.

Ethics in public health: call for shared moral public health literacy.

Science.gov (United States)

Maeckelberghe, Els L M; Schröder-Bäck, Peter

2017-10-01

Public Health (PH) in Europe has become much more vocal about its moral understandings since 1992. The rising awareness that PH issues were inseparable from issues of human rights and social justice almost self-evidently directed the agenda of EUPHA and the European Public Health (EPH)-conferences. Problems of cultural and behavioural change, and environmental issues on a global scale were also added. The Section Ethics in PH invited the EPH community to join in 'arm chair thinking': coming together at conferences not only to share the 'how' and 'what' of PH research, practices and policies but also the 'why'. Time has been reserved to genuinely discuss what moral values are at stake in the work of PH and to actively develop a moral language and framework for PH Ethics. The challenge for the next decades is to find ways to involve the general public in the cultivation of a shared moral PH literacy. © The Author 2017. Published by Oxford University Press on behalf of the European Public Health Association. All rights reserved.

Adaptive tracking control for active suspension systems with non-ideal actuators

Science.gov (United States)

Pan, Huihui; Sun, Weichao; Jing, Xingjian; Gao, Huijun; Yao, Jianyong

2017-07-01

As a critical component of transportation vehicles, active suspension systems are instrumental in the improvement of ride comfort and maneuverability. However, practical active suspensions commonly suffer from parameter uncertainties (e.g., the variations of payload mass and suspension component parameters), external disturbances and especially the unknown non-ideal actuators (i.e., dead-zone and hysteresis nonlinearities), which always significantly deteriorate the control performance in practice. To overcome these issues, this paper synthesizes an adaptive tracking control strategy for vehicle suspension systems to achieve suspension performance improvements. The proposed control algorithm is formulated by developing a unified framework of non-ideal actuators rather than a separate way, which is a simple yet effective approach to remove the unexpected nonlinear effects. From the perspective of practical implementation, the advantages of the presented controller for active suspensions include that the assumptions on the measurable actuator outputs, the prior knowledge of nonlinear actuator parameters and the uncertain parameters within a known compact set are not required. Furthermore, the stability of the closed-loop suspension system is theoretically guaranteed by rigorous mathematical analysis. Finally, the effectiveness of the presented adaptive control scheme is confirmed using comparative numerical simulation validations.

Active Detection for Exposing Intelligent Attacks in Control Systems

Energy Technology Data Exchange (ETDEWEB)

Weerakkody, Sean [Carnegie Mellon Univ., Pittsburgh, PA (United States); Ozel, Omur [Carnegie Mellon Univ., Pittsburgh, PA (United States); Griffioen, Paul [Carnegie Mellon Univ., Pittsburgh, PA (United States); Sinopoli, Bruno [Carnegie Mellon Univ., Pittsburgh, PA (United States)

2017-07-01

In this paper, we consider approaches for detecting integrity attacks carried out by intelligent and resourceful adversaries in control systems. Passive detection techniques are often incorporated to identify malicious behavior. Here, the defender utilizes finely-tuned algorithms to process information and make a binary decision, whether the system is healthy or under attack. We demonstrate that passive detection can be ineffective against adversaries with model knowledge and access to a set of input/output channels. We then propose active detection as a tool to detect attacks. In active detection, the defender leverages degrees of freedom he has in the system to detect the adversary. Specifically, the defender will introduce a physical secret kept hidden from the adversary, which can be utilized to authenticate the dynamics. In this regard, we carefully review two approaches for active detection: physical watermarking at the control input, and a moving target approach for generating system dynamics. We examine practical considerations for implementing these technologies and discuss future research directions.

A balance of activity in brain control and reward systems predicts self-regulatory outcomes.

Science.gov (United States)

Lopez, Richard B; Chen, Pin-Hao A; Huckins, Jeremy F; Hofmann, Wilhelm; Kelley, William M; Heatherton, Todd F

2017-05-01

Previous neuroimaging work has shown that increased reward-related activity following exposure to food cues is predictive of self-control failure. The balance model suggests that self-regulation failures result from an imbalance in reward and executive control mechanisms. However, an open question is whether the relative balance of activity in brain systems associated with executive control (vs reward) supports self-regulatory outcomes when people encounter tempting cues in daily life. Sixty-nine chronic dieters, a population known for frequent lapses in self-control, completed a food cue-reactivity task during an fMRI scanning session, followed by a weeklong sampling of daily eating behaviors via ecological momentary assessment. We related participants' food cue activity in brain systems associated with executive control and reward to real-world eating patterns. Specifically, a balance score representing the amount of activity in brain regions associated with self-regulatory control, relative to automatic reward-related activity, predicted dieters' control over their eating behavior during the following week. This balance measure may reflect individual self-control capacity and be useful for examining self-regulation success in other domains and populations. © The Author (2017). Published by Oxford University Press.

Optimization strategy for actuator and sensor placement in active structural acoustic control

NARCIS (Netherlands)

Oude nijhuis, M.H.H.; de Boer, Andries

2003-01-01

In active structural acoustic control the goal is to reduce the sound radiation of a structure by means of changing the vibrational behaviour of that structure. The performance of such an active control system is to a large extent determined by the locations of the actuators and sensors. In this

Computer simulations and modeling-assisted ToxR screening in deciphering 3D structures of transmembrane α-helical dimers: ephrin receptor A1

International Nuclear Information System (INIS)

Volynsky, P E; Mineeva, E A; Goncharuk, M V; Ermolyuk, Ya S; Arseniev, A S; Efremov, R G

2010-01-01

Membrane-spanning segments of numerous proteins (e.g. receptor tyrosine kinases) represent a novel class of pharmacologically important targets, whose activity can be modulated by specially designed artificial peptides, the so-called interceptors. Rational construction of such peptides requires understanding of the main factors driving peptide–peptide association in lipid membranes. Here we present a new method for rapid prediction of the spatial structure of transmembrane (TM) helix–helix complexes. It is based on computer simulations in membrane-like media and subsequent refinement/validation of the results using experimental studies of TM helix dimerization in a bacterial membrane by means of the ToxR system. The approach was applied to TM fragments of the ephrin receptor A1 (EphA1). A set of spatial structures of the dimer was proposed based on Monte Carlo simulations in an implicit membrane followed by molecular dynamics relaxation in an explicit lipid bilayer. The resulting models were employed for rational design of wild-type and mutant genetic constructions for ToxR assays. The computational and the experimental data are self-consistent and provide an unambiguous spatial model of the TM dimer of EphA1. The results of this work can be further used to develop new biologically active 'peptide interceptors' specifically targeting membrane domains of proteins

Study on the improved evaluation of radioactivity of activated control rods in PWR

International Nuclear Information System (INIS)

Waki, Toshikazu; Yamada, Motoyuki; Horikawa, Yoshihiko; Miyake, Yusuke; Sakashita, Akira

2009-01-01

The evaluation method of radioactivity of activated materials has been developed as ORIGEN code. However, it is difficult to precisely evaluate the radioactivity of neutron absorption materials such as control rods. A control rod in PWR is made of Ag-In-Cd alloy that absorbs neutron greatly and the thermal neutron flux decreases rapidly in and around it. This phenomenon is called depression effect. The consideration of depression effect is necessary to evaluate radioactivity of the control rod. In this study we improved the reliability of the cross-section value of Ag-107(n,γ) Ag-108m by the irradiation examination in JRR3. In addition, we calculated (1) the neutron spectrum and neutron flux with depression effect by MCNP of Monte Carlo method and (2) the radioactivity of the activated control rod. The pieces of control rod were irradiated at JMTR of JAERI. As a result of the accuracy of the measurement data calculation results, we developed the method of evaluation for the radioactivity of activated control rod. The radioactivity of activated control rod in PWR was evaluated and compared with the measurement data, resulting in positive accuracy. Of special significance was confirmation of the value of Ag-108m, as an essential nuclide for long term dose estimation of disposal facility. The cross-section value of Ag-107(n,γ) Ag-108m was about one forty of existent library. This method was accurately confirmed and developed for evaluating activated control rods reasonably. (author)

Active vibration control of clamped beams using positive position feedback controllers with moment pair

International Nuclear Information System (INIS)

Shin, Chang Joo; Jeong, Weui Bong; Hong, Chin Suk

2012-01-01

This paper investigates the active vibration control of clamp beams using positive position feedback (PPF) controllers with a sensor/ moment pair actuator. The sensor/moment pair actuator which is the non-collocated configuration leads to instability of the control system when using the direct velocity feedback (DVFB) control. To alleviate the instability problem, a PPF controller is considered in this paper. A parametric study of the control system with PPF controller is first conducted to characterize the effects of the design parameters (gain and damping ratio in this paper) on the stability and performance. The gain of the controller is found to affect only the relative stability. Increasing the damping ratio of the controller slightly improves the stability condition while the performance gets worse. In addition, the higher mode tuned PPF controller affects the system response at the lower modes significantly. Based on the characteristics of PPF controllers, a multi-mode controllable SISO PPF controller is then considered and tuned to different modes (in this case, three lowest modes) numerically and experimentally. The multi-mode PPF controller can be achieved to have a high gain margin. Moreover, it reduces the vibration of the beam significantly. The vibration levels at the tuned modes are reduced by about 11 dB

New design deforming controlling system of the active stressed lap

Science.gov (United States)

Ying, Li; Wang, Daxing

2008-07-01

A 450mm diameter active stressed lap has been developed in NIAOT by 2003. We design a new lap in 2007. This paper puts on emphases on introducing the new deforming control system of the lap. Aiming at the control characteristic of the lap, a new kind of digital deforming controller is designed. The controller consists of 3 parts: computer signal disposing, motor driving and force sensor signal disposing. Intelligent numeral PID method is applied in the controller instead of traditional PID. In the end, the result of new deformation are given.