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Sample records for adherens junctions connect

  1. Microtubules CLASP to Adherens Junctions in epidermal progenitor cells

    DEFF Research Database (Denmark)

    Shahbazi, Marta N; Perez-Moreno, Mirna

    2014-01-01

    Cadherin-mediated cell adhesion at Adherens Junctions (AJs) and its dynamic connections with the microtubule (MT) cytoskeleton are important regulators of cellular architecture. However, the functional relevance of these interactions and the molecular players involved in different cellular contexts...... and cellular compartments are still not completely understood. Here, we comment on our recent findings showing that the MT plus-end binding protein CLASP2 interacts with the AJ component p120-catenin (p120) specifically in progenitor epidermal cells. Absence of either protein leads to alterations in MT...... dynamics and AJ functionality. These findings represent a novel mechanism of MT targeting to AJs that may be relevant for the maintenance of proper epidermal progenitor cell homeostasis. We also discuss the potential implication of other MT binding proteins previously associated to AJs in the wider context...

  2. Flow mechanotransduction regulates traction forces, intercellular forces, and adherens junctions

    Science.gov (United States)

    Ting, Lucas H.; Jahn, Jessica R.; Jung, Joon I.; Shuman, Benjamin R.; Feghhi, Shirin; Han, Sangyoon J.; Rodriguez, Marita L.

    2012-01-01

    Endothelial cells respond to fluid shear stress through mechanotransduction responses that affect their cytoskeleton and cell-cell contacts. Here, endothelial cells were grown as monolayers on arrays of microposts and exposed to laminar or disturbed flow to examine the relationship among traction forces, intercellular forces, and cell-cell junctions. Cells under laminar flow had traction forces that were higher than those under static conditions, whereas cells under disturbed flow had lower traction forces. The response in adhesion junction assembly matched closely with changes in traction forces since adherens junctions were larger in size for laminar flow and smaller for disturbed flow. Treating the cells with calyculin-A to increase myosin phosphorylation and traction forces caused an increase in adherens junction size, whereas Y-27362 cause a decrease in their size. Since tugging forces across cell-cell junctions can promote junctional assembly, we developed a novel approach to measure intercellular forces and found that these forces were higher for laminar flow than for static or disturbed flow. The size of adherens junctions and tight junctions matched closely with intercellular forces for these flow conditions. These results indicate that laminar flow can increase cytoskeletal tension while disturbed flow decreases cytoskeletal tension. Consequently, we found that changes in cytoskeletal tension in response to shear flow conditions can affect intercellular tension, which in turn regulates the assembly of cell-cell junctions. PMID:22447948

  3. The extracellular architecture of adherens junctions revealed by crystal structures of type I cadherins.

    Science.gov (United States)

    Harrison, Oliver J; Jin, Xiangshu; Hong, Soonjin; Bahna, Fabiana; Ahlsen, Goran; Brasch, Julia; Wu, Yinghao; Vendome, Jeremie; Felsovalyi, Klara; Hampton, Cheri M; Troyanovsky, Regina B; Ben-Shaul, Avinoam; Frank, Joachim; Troyanovsky, Sergey M; Shapiro, Lawrence; Honig, Barry

    2011-02-09

    Adherens junctions, which play a central role in intercellular adhesion, comprise clusters of type I classical cadherins that bind via extracellular domains extended from opposing cell surfaces. We show that a molecular layer seen in crystal structures of E- and N-cadherin ectodomains reported here and in a previous C-cadherin structure corresponds to the extracellular architecture of adherens junctions. In all three ectodomain crystals, cadherins dimerize through a trans adhesive interface and are connected by a second, cis, interface. Assemblies formed by E-cadherin ectodomains coated on liposomes also appear to adopt this structure. Fluorescent imaging of junctions formed from wild-type and mutant E-cadherins in cultured cells confirm conclusions derived from structural evidence. Mutations that interfere with the trans interface ablate adhesion, whereas cis interface mutations disrupt stable junction formation. Our observations are consistent with a model for junction assembly involving strong trans and weak cis interactions localized in the ectodomain. Copyright © 2011 Elsevier Ltd. All rights reserved.

  4. DHT deficiency perturbs the integrity of the rat seminiferous epithelium by disrupting tight and adherens junctions

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    Barbara Wiszniewska

    2011-04-01

    Full Text Available In rats with a DHT deficiency induced by finasteride, morphological changes in the seminiferous epithelium were observed. The structural alterations were manifested by the premature germ cells sloughing into the lumen of seminiferous tubules. The etiology of this disorder could be connected with intercellular junctions disintegration. We showed in the immunohistochemical study the changes in expression of some proteins building tight and adherens junctions. The depression of N-cadherin, β-catenin and occludin immunoexpressions could be the reason for the release of immature germ cells from the seminiferous epithelium. However, the observed increase of the immunohistochemical reaction intensity of vinculin, one of the cadherin/catenin complex regulators, could be insufficient to maintain the proper function of adherens junctions. The hormonal imbalance appears to influence the pattern of expression of junctional proteins in the seminiferous epithelium. It could lead to untimely germ cells sloughing, and ultimately could impair fertility. (Folia Histochemica et Cytobiologica 2011, Vol. 49, No. 1, 62–71

  5. Fibroblast growth factor signaling potentiates VE-cadherin stability at adherens junctions by regulating SHP2.

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    Kunihiko Hatanaka

    Full Text Available The fibroblast growth factor (FGF system plays a critical role in the maintenance of vascular integrity via enhancing the stability of VE-cadherin at adherens junctions. However, the precise molecular mechanism is not well understood. In the present study, we aimed to investigate the detailed mechanism of FGF regulation of VE-cadherin function that leads to endothelial junction stabilization.In vitro studies demonstrated that the loss of FGF signaling disrupts the VE-cadherin-catenin complex at adherens junctions by increasing tyrosine phosphorylation levels of VE-cadherin. Among protein tyrosine phosphatases (PTPs known to be involved in the maintenance of the VE-cadherin complex, suppression of FGF signaling reduces SHP2 expression levels and SHP2/VE-cadherin interaction due to accelerated SHP2 protein degradation. Increased endothelial permeability caused by FGF signaling inhibition was rescued by SHP2 overexpression, indicating the critical role of SHP2 in the maintenance of endothelial junction integrity.These results identify FGF-dependent maintenance of SHP2 as an important new mechanism controlling the extent of VE-cadherin tyrosine phosphorylation, thereby regulating its presence in adherens junctions and endothelial permeability.

  6. Unraveling the mechano-responsive mechanisms at Focal Adherens Junctions

    NARCIS (Netherlands)

    Oldenburg, Joppe

    2015-01-01

    Formation and maintenance of cell-cell junctions is paramount for proper epithelial and endothelial barrier formation. Cell-cell adhesions are regulated by chemical and mechanical cues from the environment. Mechanical regulation of both epithelial and endothelial barrier occurs predominantly through

  7. The F-BAR protein pacsin2 inhibits asymmetric VE-cadherin internalization from tensile adherens junctions

    NARCIS (Netherlands)

    Dorland, Yvonne L; Malinova, Tsveta S; van Stalborch, Anne-Marieke D; Grieve, Adam G; van Geemen, Daphne; Jansen, Nicolette S; de Kreuk, Bart-Jan; Nawaz, Kalim; Kole, Jeroen; Geerts, Dirk; Musters, René J P; de Rooij, Johan; Hordijk, Peter L; Huveneers, Stephan

    2016-01-01

    Vascular homoeostasis, development and disease critically depend on the regulation of endothelial cell-cell junctions. Here we uncover a new role for the F-BAR protein pacsin2 in the control of VE-cadherin-based endothelial adhesion. Pacsin2 concentrates at focal adherens junctions (FAJs) that are

  8. The F-BAR protein pacsin2 inhibits asymmetric VE-cadherin internalization from tensile adherens junctions

    NARCIS (Netherlands)

    Dorland, Y.L. (Yvonne L.); Malinova, T.S. (Tsveta S.); Van Stalborch, A.-M.D. (Anne-Marieke D.); Grieve, A.G. (Adam G.); D. van Geemen (D.); Jansen, N.S. (Nicolette S.); B.J. de Kreuk (Bart-Jan); Nawaz, K. (Kalim); Kole, J. (Jeroen); D. Geerts (Dirk); R.J.P. Musters (René); J.D. de Rooij (Johan); P.L. Hordijk (Peter ); H. Huveneers (Hans)

    2016-01-01

    textabstractVascular homoeostasis, development and disease critically depend on the regulation of endothelial cell-cell junctions. Here we uncover a new role for the F-BAR protein pacsin2 in the control of VE-cadherin-based endothelial adhesion. Pacsin2 concentrates at focal adherens junctions

  9. Glucocorticoid receptor localizes to adherens junctions at the plasma membrane of keratinocytes.

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    Olivera Stojadinovic

    Full Text Available Glucocorticoids are important regulators of epidermal tissue homeostasis. As such, their clinical applications are widespread, ranging from inflammatory skin disorders to keloids and cancer. Glucocorticoids exert their effect by binding to glucocorticoid receptor (GR which translocates to the nucleus and regulates gene expression (genomic effect. In addition, GR has rapid non- genomic effects that are mediated by cell signaling proteins and do not involve gene transcription. Although genomic effects of GR in the epidermis are well documented, the non-genomic effects are not completely understood. Therefore, we utilized immunostaining and immunoprecipitations to determine specific localization of the GR in human keratinocytes that may contribute to non-genomic effects of glucocorticoid action. Here we describe a novel finding of GR localization to the plasma membrane of keratinocytes. Immunocytochemistry showed co-localization of GR with α-catenin. Immunoprecipitation of the membranous fraction revealed an association of GR with α-catenin, confirming its localization to adherens junctions. We conclude that GR localization to adherens junctions of keratinocytes provides a new mechanism of non-genomic signaling by glucocorticoids which may have significant biological and clinical impact.

  10. Giardia disrupts the arrangement of tight, adherens and desmosomal junction proteins of intestinal cells.

    Science.gov (United States)

    Maia-Brigagão, C; Morgado-Díaz, J A; De Souza, W

    2012-06-01

    Giardia duodenalis is a parasitic protozoan that causes diarrhea and other symptoms which together constitute a disease known as giardiasis. Although the disease has been well defined, the mechanisms involving the establishment of the infection have not yet been fully elucidated. In this study, we show that after 24h of interaction between parasites and intestinal Caco-2 cells, there was an alteration of the paracellular permeability, as observed by an approximate 42% of reduction in the transepithelial electrical resistance and permeation to ruthenium red, which was concomitant with ultrastructural changes. Nevertheless, epithelium viability was not affected. We also demonstrate that there was no change in expression of junctional proteins (tight and adherens) but that the distribution of these proteins in Caco-2 cells after parasite adhesion was significantly altered, as observed via laser scanning confocal microscopy 3D reconstruction. The present work shows that adhesion of Giardia duodenalis trophozoites to intestinal cells in vitro induces disturbances of the tight, adherens and desmosomal junctions. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  11. Carcinoembryonic antigen promotes colorectal cancer progression by targeting adherens junction complexes

    Energy Technology Data Exchange (ETDEWEB)

    Bajenova, Olga, E-mail: o.bazhenova@spbu.ru [Theodosius Dobzhansky Center for Genome Bioinformatics, St. Petersburg State University, St. Petersburg 199034 (Russian Federation); Department of Genetics and Biotechnology, St. Petersburg State University, St. Petersburg 199034 (Russian Federation); Department of Surgery and Biomedical Sciences, Creighton University, Omaha, NE 68178 (United States); Chaika, Nina [Department of Surgery and Biomedical Sciences, Creighton University, Omaha, NE 68178 (United States); Tolkunova, Elena; Davydov-Sinitsyn, Alexander [Institute of Cytology, Russian Academy of Sciences, St. Petersburg 194064 (Russian Federation); Gapon, Svetlana [Boston Children' s Hospital, Boston, MA 02115 (United States); Thomas, Peter [Department of Surgery and Biomedical Sciences, Creighton University, Omaha, NE 68178 (United States); O’Brien, Stephen [Theodosius Dobzhansky Center for Genome Bioinformatics, St. Petersburg State University, St. Petersburg 199034 (Russian Federation)

    2014-06-10

    Oncomarkers play important roles in the detection and management of human malignancies. Carcinoembryonic antigen (CEA, CEACAM5) and epithelial cadherin (E-cadherin) are considered as independent tumor markers in monitoring metastatic colorectal cancer. They are both expressed by cancer cells and can be detected in the blood serum. We investigated the effect of CEA production by MIP101 colorectal carcinoma cell lines on E-cadherin adherens junction (AJ) protein complexes. No direct interaction between E-cadherin and CEA was detected; however, the functional relationships between E-cadherin and its AJ partners: α-, β- and p120 catenins were impaired. We discovered a novel interaction between CEA and beta-catenin protein in the CEA producing cells. It is shown in the current study that CEA overexpression alters the splicing of p120 catenin and triggers the release of soluble E-cadherin. The influence of CEA production by colorectal cancer cells on the function of E-cadherin junction complexes may explain the link between the elevated levels of CEA and the increase in soluble E-cadherin during the progression of colorectal cancer. - Highlights: • Elevated level of CEA increases the release of soluble E-cadherin during the progression of colorectal cancer. • CEA over-expression alters the binding preferences between E-cadherin and its partners: α-, β- and p120 catenins in adherens junction complexes. • CEA produced by colorectal cancer cells interacts with beta-catenin protein. • CEA over-expression triggers the increase in nuclear beta-catenin. • CEA over-expression alters the splicing of p120 catenin protein.

  12. Mammary epithelial cell phagocytosis downstream of TGF-β3 is characterized by adherens junction reorganization.

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    Fornetti, J; Flanders, K C; Henson, P M; Tan, A-C; Borges, V F; Schedin, P

    2016-02-01

    After weaning, during mammary gland involution, milk-producing mammary epithelial cells undergo apoptosis. Effective clearance of these dying cells is essential, as persistent apoptotic cells have a negative impact on gland homeostasis, future lactation and cancer susceptibility. In mice, apoptotic cells are cleared by the neighboring epithelium, yet little is known about how mammary epithelial cells become phagocytic or whether this function is conserved between species. Here we use a rat model of weaning-induced involution and involuting breast tissue from women, to demonstrate apoptotic cells within luminal epithelial cells and epithelial expression of the scavenger mannose receptor, suggesting conservation of phagocytosis by epithelial cells. In the rat, epithelial transforming growth factor-β (TGF-β) signaling is increased during involution, a pathway known to promote phagocytic capability. To test whether TGF-β enhances the phagocytic ability of mammary epithelial cells, non-transformed murine mammary epithelial EpH4 cells were cultured to achieve tight junction impermeability, such as occurs during lactation. TGF-β3 treatment promoted loss of tight junction impermeability, reorganization and cleavage of the adherens junction protein E-cadherin (E-cad), and phagocytosis. Phagocytosis correlated with junction disruption, suggesting junction reorganization is necessary for phagocytosis by epithelial cells. Supporting this hypothesis, epithelial cell E-cad reorganization and cleavage were observed in rat and human involuting mammary glands. Further, in the rat, E-cad cleavage correlated with increased γ-secretase activity and β-catenin nuclear localization. In vitro, pharmacologic inhibitors of γ-secretase or β-catenin reduced the effect of TGF-β3 on phagocytosis to near baseline levels. However, β-catenin signaling through LiCl treatment did not enhance phagocytic capacity, suggesting a model in which both reorganization of cell junctions and

  13. HIV-associated disruption of tight and adherens junctions of oral epithelial cells facilitates HSV-1 infection and spread.

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    Irna Sufiawati

    Full Text Available Herpes simplex virus (HSV types 1 and 2 are the most common opportunistic infections in HIV/AIDS. In these immunocompromised individuals, HSV-1 reactivates and replicates in oral epithelium, leading to oral disorders such as ulcers, gingivitis, and necrotic lesions. Although the increased risk of HSV infection may be mediated in part by HIV-induced immune dysfunction, direct or indirect interactions of HIV and HSV at the molecular level may also play a role. In this report we show that prolonged interaction of the HIV proteins tat and gp120 and cell-free HIV virions with polarized oral epithelial cells leads to disruption of tight and adherens junctions of epithelial cells through the mitogen-activated protein kinase signaling pathway. HIV-induced disruption of oral epithelial junctions facilitates HSV-1 paracellular spread between the epithelial cells. Furthermore, HIV-associated disruption of adherens junctions exposes sequestered nectin-1, an adhesion protein and critical receptor for HSV envelope glycoprotein D (gD. Exposure of nectin-1 facilitates binding of HSV-1 gD, which substantially increases HSV-1 infection of epithelial cells with disrupted junctions over that of cells with intact junctions. Exposed nectin-1 from disrupted adherens junctions also increases the cell-to-cell spread of HSV-1 from infected to uninfected oral epithelial cells. Antibodies to nectin-1 and HSV-1 gD substantially reduce HSV-1 infection and cell-to-cell spread, indicating that HIV-promoted HSV infection and spread are mediated by the interaction of HSV gD with HIV-exposed nectin-1. Our data suggest that HIV-associated disruption of oral epithelial junctions may potentiate HSV-1 infection and its paracellular and cell-to-cell spread within the oral mucosal epithelium. This could be one of the possible mechanisms of rapid development of HSV-associated oral lesions in HIV-infected individuals.

  14. Adherens junction distribution mechanisms during cell-cell contact elongation in Drosophila.

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    Gabrielle Goldenberg

    Full Text Available During Drosophila gastrulation, amnioserosa (AS cells flatten and spread as an epithelial sheet. We used AS morphogenesis as a model to investigate how adherens junctions (AJs distribute along elongating cell-cell contacts in vivo. As the contacts elongated, total AJ protein levels increased along their length. However, genetically blocking this AJ addition indicated that it was not essential for maintaining AJ continuity. Implicating other remodeling mechanisms, AJ photobleaching revealed non-directional lateral mobility of AJs along the elongating contacts, as well as local AJ removal from the membranes. Actin stabilization with jasplakinolide reduced AJ redistribution, and live imaging of myosin II along elongating contacts revealed fragmented, expanding and contracting actomyosin networks, suggesting a mechanism for lateral AJ mobility. Actin stabilization also increased total AJ levels, suggesting an inhibition of AJ removal. Implicating AJ removal by endocytosis, clathrin endocytic machinery accumulated at AJs. However, dynamin disruption had no apparent effect on AJs, suggesting the involvement of redundant or dynamin-independent mechanisms. Overall, we propose that new synthesis, lateral diffusion, and endocytosis play overlapping roles to populate elongating cell-cell contacts with evenly distributed AJs in this in vivo system.

  15. Restricted tissue distribution of a 37-kD possible adherens junction protein.

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    Chiu, M L; Jones, J C; O'Keefe, E J

    1992-12-01

    A major polypeptide of M(r) 37,000 was purified from a desmosome-enriched citric acid-insoluble pellet of pig tongue epithelium. The polypeptide was solubilized from the 4-M urea-insoluble pellet with 9 M urea, and extracts were separated by carboxymethyl cellulose and gel filtration chromatography. The 37-kD protein was obtained in milligram quantities as a single band on two-dimensional gels in 30% yield after 21-fold purification from the citric acid-insoluble fraction. The protein is not glycosylated and has a pI of approximately 8.7. Although isolated from a fraction rich in desmosomes, the 37-kD protein is not a desmosomal protein. Indirect immunofluorescence analysis of frozen sections of tongue and other tissues demonstrated that antibodies raised to the 37-kD protein bound only to suprabasal cell layers at punctate regions of the periphery of the cell and was absent from most regions of epidermis, whereas antibodies to desmoplakins I and II, desmosomal proteins, bound similarly but in all epidermal layers. Immunoelectron microscopy localized the 37-kD protein to the cell periphery in regions between, but never in, desmosomes. By immunofluorescence, the 37-kD protein colocalized with actin as well as with vinculin and uvomorulin in oral tissues. Like the 37-kD protein, vinculin and uvomorulin were absent from the basal layer. Based on its appearance, localization, and solubility properties, the 37-kD protein is probably a component of adherens junctions; its restriction to suprabasal cells and exclusion from the epidermis are unique.

  16. Genetic deletion of afadin causes hydrocephalus by destruction of adherens junctions in radial glial and ependymal cells in the midbrain.

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    Hideaki Yamamoto

    Full Text Available Adherens junctions (AJs play a role in mechanically connecting adjacent cells to maintain tissue structure, particularly in epithelial cells. The major cell-cell adhesion molecules at AJs are cadherins and nectins. Afadin binds to both nectins and α-catenin and recruits the cadherin-β-catenin complex to the nectin-based cell-cell adhesion site to form AJs. To explore the role of afadin in radial glial and ependymal cells in the brain, we generated mice carrying a nestin-Cre-mediated conditional knockout (cKO of the afadin gene. Newborn afadin-cKO mice developed hydrocephalus and died neonatally. The afadin-cKO brain displayed enlarged lateral ventricles and cerebral aqueduct, resulting from stenosis of the caudal end of the cerebral aqueduct and obliteration of the ventral part of the third ventricle. Afadin deficiency further caused the loss of ependymal cells from the ventricular and aqueductal surfaces. During development, radial glial cells, which terminally differentiate into ependymal cells, scattered from the ventricular zone and were replaced by neurons that eventually covered the ventricular and aqueductal surfaces of the afadin-cKO midbrain. Moreover, the denuded ependymal cells were only occasionally observed in the third ventricle and the cerebral aqueduct of the afadin-cKO midbrain. Afadin was co-localized with nectin-1 and N-cadherin at AJs of radial glial and ependymal cells in the control midbrain, but these proteins were not concentrated at AJs in the afadin-cKO midbrain. Thus, the defects in the afadin-cKO midbrain most likely resulted from the destruction of AJs, because AJs in the midbrain were already established before afadin was genetically deleted. These results indicate that afadin is essential for the maintenance of AJs in radial glial and ependymal cells in the midbrain and is required for normal morphogenesis of the cerebral aqueduct and ventral third ventricle in the midbrain.

  17. Protein p0071, an armadillo plaque protein of adherens junctions, is predominantly expressed in distal renal tubules.

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    Walter, Britta; Krebs, Ulrike; Berger, Irina; Hofmann, Ilse

    2010-01-01

    Protein p0071 is a member of the p120-subfamily of armadillo proteins and is well known as a junctional plaque component involved in cell-cell adhesion, especially in adherens junctions. By systematic immunohistochemical analysis of mouse and human kidney tissues, p0071 was prominently detected in distinct kidney tubules. Upon double-labeling immunolocalization experiments with segment-specific markers, p0071 was predominantly localized in distal straight and convoluted tubules and to a lesser extent in proximal tubules, in the ascending thin limb of loop of Henle and in the collecting ducts. In capillaries of the kidney, p0071 co-localized with VE-cadherin an endothelium-specific cadherin. Protein p0071 was also detected in both, renal cell carcinomas derived from distal tubules and in maturing nephrons of early mouse developmental stages. Immunoblotting of total extracts of cultured cells of renal origin showed that p0071 was detected in all human and murine cells analyzed. Upon immunolocalization, p0071 was observed in adherens junctions but also in distinct cytoplasmic structures at the cell periphery of cultured cells. Possible structural and functional roles of p0071 are suggested by its preferential occurrence in distinct tubule segments, and its potential use as a cytodiagnostic cell type marker in renal pathology is discussed.

  18. Alteration of Tight and Adherens Junctions on 50-Hz Magnetic Field Exposure in Madin Darby Canine Kidney (MDCK Cells

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    Zoltán Somosy

    2004-01-01

    Full Text Available Adherens (AJ and tight junctions (TJ, as integrated parts of the junctional complex, are multifunctional specialized regions of the cell membrane in epithelial cells. They are responsible for cell-to-cell interactions and also have great importance in cellular signaling processes including Wnt protein-mediated signals. As electromagnetic field (EMF exposure is known to cause alterations in the function as well as supramolecular organization of different cell contacts, our goal was to investigate the effect of 50-Hz magnetic field (MF exposures on the subcellular distribution of some representative structural proteins (occludin, β-catenin, and cadherin found in AJ and TJ. Additionally, cellular β-catenin content was also quantified by Western blot analysis. 50-Hz MF exposures seemed to increase the staining intensity (amount of occludin, cadherins, and β-catenin in the junctional area of MDCK cells, while Western blot data indicated the quantity of b-catenin was found significantly decreased at both time points after EM exposures. Our results demonstrate that MF are able to modify the distribution of TJ and AJ structural proteins, tending to stabilize these cell contacts. The quantitative changes of β-catenin suggest a causative relationship between MF effects on the cell junctional complex and the Wnt signaling pathway.

  19. Leptospira interrogans causes quantitative and morphological disturbances in adherens junctions and other biological groups of proteins in human endothelial cells.

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    Hiromi Sato

    2017-07-01

    Full Text Available Pathogenic Leptospira transmits from animals to humans, causing the zoonotic life-threatening infection called leptospirosis. This infection is reported worldwide with higher risk in tropical regions. Symptoms of leptospirosis range from mild illness to severe illness such as liver damage, kidney failure, respiratory distress, meningitis, and fatal hemorrhagic disease. Invasive species of Leptospira rapidly disseminate to multiple tissues where this bacterium damages host endothelial cells, increasing vascular permeability. Despite the burden in humans and animals, the pathogenic mechanisms of Leptospira infection remain to be elucidated. The pathogenic leptospires adhere to endothelial cells and permeabilize endothelial barriers in vivo and in vitro. In this study, human endothelial cells were infected with the pathogenic L. interrogans serovar Copenhageni or the saprophyte L. biflexa serovar Patoc to investigate morphological changes and other distinctive phenotypes of host cell proteins by fluorescence microscopy. Among those analyzed, 17 proteins from five biological classes demonstrated distinctive phenotypes in morphology and/or signal intensity upon infection with Leptospira. The affected biological groups include: 1 extracellular matrix, 2 intercellular adhesion molecules and cell surface receptors, 3 intracellular proteins, 4 cell-cell junction proteins, and 5 a cytoskeletal protein. Infection with the pathogenic strain most profoundly disturbed the biological structures of adherens junctions (VE-cadherin and catenins and actin filaments. Our data illuminate morphological disruptions and reduced signals of cell-cell junction proteins and filamentous actin in L. interrogans-infected endothelial cells. In addition, Leptospira infection, regardless of pathogenic status, influenced other host proteins belonging to multiple biological classes. Our data suggest that this zoonotic agent may damage endothelial cells via multiple cascades or

  20. Leptospira interrogans causes quantitative and morphological disturbances in adherens junctions and other biological groups of proteins in human endothelial cells

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    Sato, Hiromi

    2017-01-01

    Pathogenic Leptospira transmits from animals to humans, causing the zoonotic life-threatening infection called leptospirosis. This infection is reported worldwide with higher risk in tropical regions. Symptoms of leptospirosis range from mild illness to severe illness such as liver damage, kidney failure, respiratory distress, meningitis, and fatal hemorrhagic disease. Invasive species of Leptospira rapidly disseminate to multiple tissues where this bacterium damages host endothelial cells, increasing vascular permeability. Despite the burden in humans and animals, the pathogenic mechanisms of Leptospira infection remain to be elucidated. The pathogenic leptospires adhere to endothelial cells and permeabilize endothelial barriers in vivo and in vitro. In this study, human endothelial cells were infected with the pathogenic L. interrogans serovar Copenhageni or the saprophyte L. biflexa serovar Patoc to investigate morphological changes and other distinctive phenotypes of host cell proteins by fluorescence microscopy. Among those analyzed, 17 proteins from five biological classes demonstrated distinctive phenotypes in morphology and/or signal intensity upon infection with Leptospira. The affected biological groups include: 1) extracellular matrix, 2) intercellular adhesion molecules and cell surface receptors, 3) intracellular proteins, 4) cell-cell junction proteins, and 5) a cytoskeletal protein. Infection with the pathogenic strain most profoundly disturbed the biological structures of adherens junctions (VE-cadherin and catenins) and actin filaments. Our data illuminate morphological disruptions and reduced signals of cell-cell junction proteins and filamentous actin in L. interrogans-infected endothelial cells. In addition, Leptospira infection, regardless of pathogenic status, influenced other host proteins belonging to multiple biological classes. Our data suggest that this zoonotic agent may damage endothelial cells via multiple cascades or pathways

  1. The PDZ-GEF protein Dizzy regulates the establishment of adherens junctions required for ventral furrow formation in Drosophila.

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    Spahn, Philipp; Ott, Alice; Reuter, Rolf

    2012-08-15

    The PDZ-GEF protein Dizzy (Dzy) and its downstream GTPase Rap1 have pleiotropic roles during development of the Drosophila embryo. Here, we show that maternally provided Dzy and Rap1 first function during ventral furrow formation (VFF) where they are critical to guarantee rapid apical cell constrictions. Contraction of the apical actomyosin filament system occurs independently of Dzy and Rap1, but loss of Dzy results in a delayed establishment of the apical adherens junction (AJ) belt, whereas in the absence of Rap1 only a fragmentary apical AJ belt is formed in the epithelium. The timely establishment of apical AJs appears to be essential for coupling actomyosin contractions to cell shape change and to assure completion of the ventral furrow. Immediately after VFF, the downregulation of Dzy and Rap1 is necessary to allow normal mesodermal development to continue after the epithelial-to-mesenchymal transition, as overexpression of Dzy or of constitutively active Rap1 compromises mesodermal migration and monolayer formation. We propose that Dzy and Rap1 are crucial factors regulating the dynamics of AJs during gastrulation.

  2. Ultrastructural analysis of the structure and distribution of the adherens junctions in the rats’ ventricular myocardium during postnatal stages of ontogeny after the infl uence of chronic prenatal hypoxia

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    N. S. Petruk

    2013-12-01

    Full Text Available Background. Antenatal and prenatal hypoxia causes changes in all the organs of fetuses and newborns and in the heart, particularly. Hypoxic damage of the cardiovascular system occurs in 40-70% of newborns. Currently we observe the increase of meaning of the morphological studies for the prenatal diagnosis of human’s heart diseases. It’s known that in adaptive remodeling of cardiomyocytes in the postnatal cardiogenesis of rat redistribution of diffusely located intercellular junctions from the periphery to the terminal areas of the cell occurs. The formation of a definitive pattern of intercellular junctions is completed at the puberty. But how chronic prenatal hypoxia influences the specialized adherens junctions in the rats’ ventricular myocardium is completely unknown and this requires further study. Objective. To provide complex qualitative and quantitative comparative ultrastructural analysis of the intercellular connection changes in rat ventricular myocardium on the stages of postnatal ontogenesis in the norm and under the chronic fetal hypoxia. Materials and methods. We have conducted ultrastructural analysis and distribution of the adherens junctions in the rats’ ventricles on the 1st, 3rd, 7th, 14th, 30th days during postnatal ontogeny and among mature animals in the normal development and under the chronic fetal hypoxia. Experimental chronic hypoxia was modeled by intraperitoneal injection of 1% aqueous solution of the NaNO2 in a daily dose of 50 mg/kg of body weight in the term from 10th to 21st days of pregnancy. Transmission electron microscopy, morphometric and statistical methods were applied. Pairwise comparisons between means of different groups were performed using a Student t-test where, for each couple of normally distributed populations, the null hypothesis that the means are equal was verified. Results. Pronounced increase (80,6%; p <0,05 of the content of desmosomes in the intercalated disk in the period from 7th

  3. CMTM3 (CKLF-Like Marvel Transmembrane Domain 3) Mediates Angiogenesis by Regulating Cell Surface Availability of VE-Cadherin in Endothelial Adherens Junctions.

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    Chrifi, Ihsan; Louzao-Martinez, Laura; Brandt, Maarten; van Dijk, Christian G M; Burgisser, Petra; Zhu, Changbin; Kros, Johan M; Duncker, Dirk J; Cheng, Caroline

    2017-06-01

    Decrease in VE-cadherin adherens junctions reduces vascular stability, whereas disruption of adherens junctions is a requirement for neovessel sprouting during angiogenesis. Endocytosis plays a key role in regulating junctional strength by altering bioavailability of cell surface proteins, including VE-cadherin. Identification of new mediators of endothelial endocytosis could enhance our understanding of angiogenesis. Here, we assessed the function of CMTM3 (CKLF-like MARVEL transmembrane domain 3), which we have previously identified as highly expressed in Flk1 + endothelial progenitor cells during embryonic development. Using a 3-dimensional coculture of human umbilical vein endothelial cells-GFP (green fluorescent protein) and pericytes-RFP (red fluorescent protein), we demonstrated that siRNA-mediated CMTM3 silencing in human umbilical vein endothelial cells impairs angiogenesis. In vivo CMTM3 inhibition by morpholino injection in developing zebrafish larvae confirmed that CMTM3 expression is required for vascular sprouting. CMTM3 knockdown in human umbilical vein endothelial cells does not affect proliferation or migration. Intracellular staining demonstrated that CMTM3 colocalizes with early endosome markers EEA1 (early endosome marker 1) and Clathrin + vesicles and with cytosolic VE-cadherin in human umbilical vein endothelial cells. Adenovirus-mediated CMTM3 overexpression enhances endothelial endocytosis, shown by an increase in Clathrin + , EEA1 + , Rab11 + , Rab5 + , and Rab7 + vesicles. CMTM3 overexpression enhances, whereas CMTM3 knockdown decreases internalization of cell surface VE-cadherin in vitro. CMTM3 promotes loss of endothelial barrier function in thrombin-induced responses, shown by transendothelial electric resistance measurements in vitro. In this study, we have identified a new regulatory function for CMTM3 in angiogenesis. CMTM3 is involved in VE-cadherin turnover and is a regulator of the cell surface pool of VE-cadherin. Therefore, CMTM

  4. Bistable front dynamics in a contractile medium: Travelling wave fronts and cortical advection define stable zones of RhoA signaling at epithelial adherens junctions

    Science.gov (United States)

    Budnar, Srikanth; Yap, Alpha S.

    2017-01-01

    Mechanical coherence of cell layers is essential for epithelia to function as tissue barriers and to control active tissue dynamics during morphogenesis. RhoA signaling at adherens junctions plays a key role in this process by coupling cadherin-based cell-cell adhesion together with actomyosin contractility. Here we propose and analyze a mathematical model representing core interactions involved in the spatial localization of junctional RhoA signaling. We demonstrate how the interplay between biochemical signaling through positive feedback, combined with diffusion on the cell membrane and mechanical forces generated in the cortex, can determine the spatial distribution of RhoA signaling at cell-cell junctions. This dynamical mechanism relies on the balance between a propagating bistable signal that is opposed by an advective flow generated by an actomyosin stress gradient. Experimental observations on the behavior of the system when contractility is inhibited are in qualitative agreement with the predictions of the model. PMID:28273072

  5. Bistable front dynamics in a contractile medium: Travelling wave fronts and cortical advection define stable zones of RhoA signaling at epithelial adherens junctions.

    Directory of Open Access Journals (Sweden)

    Rashmi Priya

    2017-03-01

    Full Text Available Mechanical coherence of cell layers is essential for epithelia to function as tissue barriers and to control active tissue dynamics during morphogenesis. RhoA signaling at adherens junctions plays a key role in this process by coupling cadherin-based cell-cell adhesion together with actomyosin contractility. Here we propose and analyze a mathematical model representing core interactions involved in the spatial localization of junctional RhoA signaling. We demonstrate how the interplay between biochemical signaling through positive feedback, combined with diffusion on the cell membrane and mechanical forces generated in the cortex, can determine the spatial distribution of RhoA signaling at cell-cell junctions. This dynamical mechanism relies on the balance between a propagating bistable signal that is opposed by an advective flow generated by an actomyosin stress gradient. Experimental observations on the behavior of the system when contractility is inhibited are in qualitative agreement with the predictions of the model.

  6. Quantitative cell polarity imaging defines leader-to-follower transitions during collective migration and the key role of microtubule-dependent adherens junction formation.

    Science.gov (United States)

    Revenu, Céline; Streichan, Sebastian; Donà, Erika; Lecaudey, Virginie; Hufnagel, Lars; Gilmour, Darren

    2014-03-01

    The directed migration of cell collectives drives the formation of complex organ systems. A characteristic feature of many migrating collectives is a 'tissue-scale' polarity, whereby 'leader' cells at the edge of the tissue guide trailing 'followers' that become assembled into polarised epithelial tissues en route. Here, we combine quantitative imaging and perturbation approaches to investigate epithelial cell state transitions during collective migration and organogenesis, using the zebrafish lateral line primordium as an in vivo model. A readout of three-dimensional cell polarity, based on centrosomal-nucleus axes, allows the transition from migrating leaders to assembled followers to be quantitatively resolved for the first time in vivo. Using live reporters and a novel fluorescent protein timer approach, we investigate changes in cell-cell adhesion underlying this transition by monitoring cadherin receptor localisation and stability. This reveals that while cadherin 2 is expressed across the entire tissue, functional apical junctions are first assembled in the transition zone and become progressively more stable across the leader-follower axis of the tissue. Perturbation experiments demonstrate that the formation of these apical adherens junctions requires dynamic microtubules. However, once stabilised, adherens junction maintenance is microtubule independent. Combined, these data identify a mechanism for regulating leader-to-follower transitions within migrating collectives, based on the relocation and stabilisation of cadherins, and reveal a key role for dynamic microtubules in this process.

  7. Pivotal role of MUC1 glycosylation by cigarette smoke in modulating disruption of airway adherens junctions in vitro.

    Science.gov (United States)

    Zhang, Lili; Gallup, Marianne; Zlock, Lorna; Chen, Yu Ting Feeling; Finkbeiner, Walter E; McNamara, Nancy A

    2014-09-01

    Cigarette smoke increases the risk of lung cancer by 20-fold and accounts for 87% of lung cancer deaths. In the normal airway, heavily O-glycosylated mucin-1 (MUC1) and adherens junctions (AJs) establish a structural barrier that protects the airway from infectious, inflammatory and noxious stimuli. Smoke disrupts cell-cell adhesion via its damaging effects on the AJ protein epithelial cadherin (E-cad). Loss of E-cad is a major hallmark of epithelial-mesenchymal transition (EMT) and has been reported in lung cancer, where it is associated with invasion, metastasis and poor prognosis. Using organotypic cultures of primary human bronchial epithelial (HBE) cells treated with smoke-concentrated medium (Smk), we have demonstrated that E-cad loss is regulated through the aberrant interaction of its AJ binding partner, p120-catenin (p120ctn), and the C-terminus of MUC1 (MUC1-C). Here, we reported that even before MUC1-C became bound to p120ctn, smoke promoted the generation of a novel 400 kDa glycoform of MUC1's N-terminus (MUC1-N) differing from the 230 kDa and 150 kDa glycoforms in untreated control cells. The subsequent smoke-induced, time-dependent shedding of glycosylated MUC1-N exposed MUC1-C as a putative receptor for interactions with EGFR, Src and p120ctn. Smoke-induced MUC1-C glycosylation modulated MUC1-C tyrosine phosphorylation (TyrP) that was essential for MUC1-C/p120ctn interaction through dose-dependent bridging of Src/MUC1-C/galectin-3/EGFR signalosomes. Chemical deglycosylation of MUC1 using a mixture of N-glycosylation inhibitor tunicamycin and O-glycosylation inhibitor benzyl-α-GalNAc disrupted the Src/MUC1-C/galectin-3/EGFR complexes and thereby abolished smoke-induced MUC1-C-TyrP and MUC1-C/p120ctn interaction. Similarly, inhibition of smoke-induced MUC1-N glycosylation using adenoviral shRNA directed against N-acetyl-galactosaminyl transferase-6 (GALNT6, an enzyme that controls the initiating step of O-glycosylation) successfully suppressed MUC1-C

  8. Folliculin, the product of the Birt-Hogg-Dube tumor suppressor gene, interacts with the adherens junction protein p0071 to regulate cell-cell adhesion.

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    Doug A Medvetz

    Full Text Available Birt-Hogg-Dube (BHD is a tumor suppressor gene syndrome associated with fibrofolliculomas, cystic lung disease, and chromophobe renal cell carcinoma. In seeking to elucidate the pathogenesis of BHD, we discovered a physical interaction between folliculin (FLCN, the protein product of the BHD gene, and p0071, an armadillo repeat containing protein that localizes to the cytoplasm and to adherens junctions. Adherens junctions are one of the three cell-cell junctions that are essential to the establishment and maintenance of the cellular architecture of all epithelial tissues. Surprisingly, we found that downregulation of FLCN leads to increased cell-cell adhesion in functional cell-based assays and disruption of cell polarity in a three-dimensional lumen-forming assay, both of which are phenocopied by downregulation of p0071. These data indicate that the FLCN-p0071 protein complex is a negative regulator of cell-cell adhesion. We also found that FLCN positively regulates RhoA activity and Rho-associated kinase activity, consistent with the only known function of p0071. Finally, to examine the role of Flcn loss on cell-cell adhesion in vivo, we utilized keratin-14 cre-recombinase (K14-cre to inactivate Flcn in the mouse epidermis. The K14-Cre-Bhd(flox/flox mice have striking delays in eyelid opening, wavy fur, hair loss, and epidermal hyperplasia with increased levels of mammalian target of rapamycin complex 1 (mTORC1 activity. These data support a model in which dysregulation of the FLCN-p0071 interaction leads to alterations in cell adhesion, cell polarity, and RhoA signaling, with broad implications for the role of cell-cell adhesion molecules in the pathogenesis of human disease, including emphysema and renal cell carcinoma.

  9. 'Special K' and a Loss of Cell-To-Cell Adhesion in Proximal Tubule-Derived Epithelial Cells: Modulation of the Adherens Junction Complex by Ketamine

    Science.gov (United States)

    Hills, Claire E.; Jin, Tianrong; Siamantouras, Eleftherios; Liu, Issac K-K; Jefferson, Kieran P.; Squires, Paul E.

    2013-01-01

    Ketamine, a mild hallucinogenic class C drug, is the fastest growing ‘party drug’ used by 16–24 year olds in the UK. As the recreational use of Ketamine increases we are beginning to see the signs of major renal and bladder complications. To date however, we know nothing of a role for Ketamine in modulating both structure and function of the human renal proximal tubule. In the current study we have used an established model cell line for human epithelial cells of the proximal tubule (HK2) to demonstrate that Ketamine evokes early changes in expression of proteins central to the adherens junction complex. Furthermore we use AFM single-cell force spectroscopy to assess if these changes functionally uncouple cells of the proximal tubule ahead of any overt loss in epithelial cell function. Our data suggests that Ketamine (24–48 hrs) produces gross changes in cell morphology and cytoskeletal architecture towards a fibrotic phenotype. These physical changes matched the concentration-dependent (0.1–1 mg/mL) cytotoxic effect of Ketamine and reflect a loss in expression of the key adherens junction proteins epithelial (E)- and neural (N)-cadherin and β-catenin. Down-regulation of protein expression does not involve the pro-fibrotic cytokine TGFβ, nor is it regulated by the usual increase in expression of Slug or Snail, the transcriptional regulators for E-cadherin. However, the loss in E-cadherin can be partially rescued pharmacologically by blocking p38 MAPK using SB203580. These data provide compelling evidence that Ketamine alters epithelial cell-to-cell adhesion and cell-coupling in the proximal kidney via a non-classical pro-fibrotic mechanism and the data provides the first indication that this illicit substance can have major implications on renal function. Understanding Ketamine-induced renal pathology may identify targets for future therapeutic intervention. PMID:24009666

  10. Downregulation of blood-brain barrier phenotype by proinflammatory cytokines involves NADPH oxidase-dependent ROS generation: consequences for interendothelial adherens and tight junctions.

    Directory of Open Access Journals (Sweden)

    Keith D Rochfort

    Full Text Available Blood-brain barrier (BBB dysfunction is an integral feature of neurological disorders and involves the action of multiple proinflammatory cytokines on the microvascular endothelial cells lining cerebral capillaries. There is still however, considerable ambiguity throughout the scientific literature regarding the mechanistic role(s of cytokines in this context, thereby warranting a comprehensive in vitro investigation into how different cytokines may cause dysregulation of adherens and tight junctions leading to BBB permeabilization.The present study employs human brain microvascular endothelial cells (HBMvECs to compare/contrast the effects of TNF-α and IL-6 on BBB characteristics ranging from the expression of interendothelial junction proteins (VE-cadherin, occludin and claudin-5 to endothelial monolayer permeability. The contribution of cytokine-induced NADPH oxidase activation to altered barrier phenotype was also investigated.In response to treatment with either TNF-α or IL-6 (0-100 ng/ml, 0-24 hrs, our studies consistently demonstrated significant dose- and time-dependent decreases in the expression of all interendothelial junction proteins examined, in parallel with dose- and time-dependent increases in ROS generation and HBMvEC permeability. Increased expression and co-association of gp91 and p47, pivotal NADPH oxidase subunits, was also observed in response to either cytokine. Finally, cytokine-dependent effects on junctional protein expression, ROS generation and endothelial permeability could all be attenuated to a comparable extent using a range of antioxidant strategies, which included ROS depleting agents (superoxide dismutase, catalase, N-acetylcysteine, apocynin and targeted NADPH oxidase blockade (gp91 and p47 siRNA, NSC23766.A timely and wide-ranging investigation comparing the permeabilizing actions of TNF-α and IL-6 in HBMvECs is presented, in which we demonstrate how either cytokine can similarly downregulate the

  11. Disruption of endothelial adherens junction by invasive breast cancer cells is mediated by reactive oxygen species and is attenuated by AHCC.

    Science.gov (United States)

    Haidari, Mehran; Zhang, Wei; Wakame, Koji

    2013-12-18

    The effect of antioxidants on treatment of cancer is still controversial. Previously, we demonstrated that interaction of breast cancer cells with endothelial cells leads to tyrosine phosphorylation of VE-cadherin and disruption of endothelial adherens junction (EAJ). The molecular mechanism underlying the anti-metastatic effects of mushroom-derived active hexode correlated compound (AHCC) remains elusive. Several cellular and biochemical techniques were used to determine the contribution of oxidative stress in the disruption of EAJ and to test this hypothesis that AHCC inhibits the breast cancer cell-induced disruption of EAJ. Interaction of breast cancer cells (MDA-MB-231 cells) with human umbilical vein endothelial cells (HUVECs) leads to an increase in generation of reactive oxygen species (ROS). Treatment of HUVECs with H2O2 or phorbol myristate acetate (PMA) led to tyrosine phosphorylation of VE-cadherin, dissociation of β-catenin from VE-cadherin complex and increased transendothelial migration (TEM) of MDA-MB-231 cells. Induction of VE-cadherin tyrosine phosphorylation by PMA or by interaction of MDA-MB-231 cells with HUVECs was mediated by HRas and protein kinase C-α signaling pathways. Disruption of EAJ and phosphorylation of VE-cadherin induced by interaction of MDA-MB-231 cells with HUVECs were attenuated when HUVECs were pretreated with an antioxidant, N-acetylcysteine (NAC) or AHCC. AHCC inhibited TEM of MDA-MB-231 cells and generation of ROS induced by interaction of MDA-MB-231 cells with HUVECs. Our studies suggest that ROS contributes to disruption of EAJ induced by interaction of MDA-MB-231 cells with HUVECs and AHCC attenuates this alteration. Copyright © 2013 Elsevier Inc. All rights reserved.

  12. Cigarette smoke disrupts the integrity of airway adherens junctions through the aberrant interaction of p120-catenin with the cytoplasmic tail of MUC1

    Science.gov (United States)

    Zhang, Lili; Gallup, Marianne; Zlock, Lorna; Basbaum, Carol; Finkbeiner, Walter E.; McNamara, Nancy A.

    2014-01-01

    Adherens junctions (AJs) containing epithelial cadherin (E-cad) bound to p120-catenin (p120ctn) and β-catenin (β-ctn) play a crucial role in regulating cell–cell adhesion. Cigarette smoke abrogates cell–cell adhesion between epithelial cells by disrupting E-cad, a hallmark of epithelial–mesenchymal transition (EMT), yet the underlying mechanism remains unknown. We used an organotypic culture of primary human bronchial epithelial (HBE) cells treated with smoke-concentrated medium (Smk) to establish an essential role for the interaction between p120ctn and the cytoplasmic tail of MUC1 (MUC1-CT) in regulating E-cad disruption. Within the first 4 h of smoke exposure, apical MUC1-CT repositioned to the basolateral membrane of pseudo-stratified HBE cells, where it interacted with p120ctn. A time-dependent increase in MUC1-CT/p120ctn complexes occurred in conjunction with a time-dependent dissociation of p120ctn/E-cad/β-ctn complexes, as well as the coordinated degradation of p120ctn and E-cad. Interestingly, Smk induced a similar interaction between MUC1-CT and β-ctn, but this occurred 44 h after MUC1-CT’s initial interaction with p120ctn, and well after the AJs were destroyed. Blocking MUC1-CT’s interaction with p120ctn using a MUC1-CT dominant-negative peptide, PMIP, successfully abolished Smk’s disruptive effects on AJs and recovered apical-basolateral polarity of HBE cells. The MUC1-CT/p120ctn interaction was highly dependent on EGFR/Src/Jnk-mediated tyrosine phosphorylation (TyrP) of MUC1-CT. Accordingly, EGFR, Src or Jnk inhibitors (AG1478, PP2, SP600125, respectively) abrogated Smk-induced MUC1-CT-TyrP, MUC1-CT/p120ctn interaction, AJ disruption, and loss of cellular polarity. Our work identified MUC1-CT and p120ctn as important regulators of epithelial polarity and cell-cell adhesion during a smoke-induced EMT-like process. Novel therapeutics designed to inhibit MUC1-CT/p120ctn complex formation may prevent EMT in the smoker’s airway. PMID

  13. VASP, zyxin and TES are tension-dependent members of Focal Adherens Junctions independent of the α-catenin-vinculin module

    NARCIS (Netherlands)

    Oldenburg, Joppe; van der Krogt, Gerard; Twiss, Floor; Bongaarts, Annika; Habani, Yasmin; Slotman, Johan A.; Houtsmuller, Adriaan; Huveneers, Stephan; De Rooij, Johan

    2015-01-01

    Mechanical forces are integrated at cadherin-based adhesion complexes to regulate morphology and strength of cell-cell junctions and organization of associated F-actin. A central mechanosensor at the cadherin complex is α-catenin, whose stretching recruits vinculin to regulate adhesion strength. The

  14. VASP, zyxin and TES are tension-dependent members of Focal Adherens Junctions independent of the α-catenin-vinculin module

    NARCIS (Netherlands)

    J. Oldenburg (Joppe); G. Van Der Krogt (Gerard); F. Twiss (Floor); A. Bongaarts (Annika); Y. Habani (Yasmin); J.A. Slotman (Johan A.); A.B. Houtsmuller (Adriaan); H. Huveneers (Hans); J.D. de Rooij (Johan)

    2015-01-01

    textabstractMechanical forces are integrated at cadherin-based adhesion complexes to regulate morphology and strength of cell-cell junctions and organization of associated F-actin. A central mechanosensor at the cadherin complex is α-catenin, whose stretching recruits vinculin to regulate adhesion

  15. Thermoelectric transport properties in graphene connected molecular junctions

    Science.gov (United States)

    Rodriguez, S. T.; Grosu, I.; Crisan, M.; Ţifrea, I.

    2018-02-01

    We study the electronic contribution to the main thermoelectric properties of a molecular junction consisting of a single quantum dot coupled to graphene external leads. The system electrical conductivity (G), Seebeck coefficient (S), and the thermal conductivity (κ), are numerically calculated based on a Green's function formalism that includes contributions up to the Hartree-Fock level. We consider the system leads to be made either of pure or gapped-graphene. To describe the free electrons in the gapped-graphene electrodes we used two possible scenarios, the massive gap scenario, and the massless gap scenario, respectively. In all cases, the Fano effect is responsible for a strong violation of the Wiedemann-Franz law and we found a substantial increase of the system figure of merit ZT due to a drastic reduction of the system thermal coefficient. In the case of gapped-graphene electrodes, the system figure of merit presents a maximum at an optimal value of the energy gap of the order of Δ / D ∼ 0.002 (massive gap scenario) and Δ / D ∼ 0.0026 (massless gap scenario). Additionally, for all cases, the system figure of merit is temperature dependent.

  16. Intercellular junctions in rabbit eye ora serrata.

    Science.gov (United States)

    Nobeschi, L; Freymuller, E; Smith, R L

    2006-10-01

    Summary The aim of this study was to describe and localize the intercellular junctions in the ora serrata region of albino and pigmented rabbit eyes. Eyes of albino and pigmented rabbits were fixed and processed for transmission electron microscopy. Light and electron microscope examination was carried out on semithin and ultrathin sections. The ora serrata region showed adherens, gap and tight junctions in the retinal and ciliary margins of albino and pigmented rabbit eyes. In the retinal margin, zonulae adherens between Müller cells and photoreceptors are associated with tight junctions. In the ciliary margin, epithelial cells are joined by adherens, gap and tight junctions localized between apical and apicolateral cell membranes. Tight junctions appear as zonulae occludens in the non-pigmented apicolateral cell membranes and as tight focal junctions between pigmented and non-pigmented apical cell membranes. Between the ciliary and retinal margins there are adherens and tight focal junctions which attach pigmented apical cell membranes to adjacent cells. There were no differences in the distribution of intercellular junctions between albino and pigmented rabbits.

  17. Mechanics of lipid bilayer junctions affecting the size of a connecting lipid nanotube

    Directory of Open Access Journals (Sweden)

    Voinova Marina

    2011-01-01

    Full Text Available Abstract In this study we report a physical analysis of the membrane mechanics affecting the size of the highly curved region of a lipid nanotube (LNT that is either connected between a lipid bilayer vesicle and the tip of a glass microinjection pipette (tube-only or between a lipid bilayer vesicle and a vesicle that is attached to the tip of a glass microinjection pipette (two-vesicle. For the tube-only configuration (TOC, a micropipette is used to pull a LNT into the interior of a surface-immobilized vesicle, where the length of the tube L is determined by the distance of the micropipette to the vesicle wall. For the two-vesicle configuration (TVC, a small vesicle is inflated at the tip of the micropipette tip and the length of the tube L is in this case determined by the distance between the two interconnected vesicles. An electrochemical method monitoring diffusion of electroactive molecules through the nanotube has been used to determine the radius of the nanotube R as a function of nanotube length L for the two configurations. The data show that the LNT connected in the TVC constricts to a smaller radius in comparison to the tube-only mode and that tube radius shrinks at shorter tube lengths. To explain these electrochemical data, we developed a theoretical model taking into account the free energy of the membrane regions of the vesicles, the LNT and the high curvature junctions. In particular, this model allows us to estimate the surface tension coefficients from R(L measurements.

  18. Desmosomal Molecules In and Out of Adhering Junctions: Normal and Diseased States of Epidermal, Cardiac and Mesenchymally Derived Cells

    Directory of Open Access Journals (Sweden)

    Sebastian Pieperhoff

    2010-01-01

    Full Text Available Current cell biology textbooks mention only two kinds of cell-to-cell adhering junctions coated with the cytoplasmic plaques: the desmosomes (maculae adhaerentes, anchoring intermediate-sized filaments (IFs, and the actin microfilament-anchoring adherens junctions (AJs, including both punctate (puncta adhaerentia and elongate (fasciae adhaerentes structures. In addition, however, a series of other junction types has been identified and characterized which contain desmosomal molecules but do not fit the definition of desmosomes. Of these special cell-cell junctions containing desmosomal glycoproteins or proteins we review the composite junctions (areae compositae connecting the cardiomyocytes of mature mammalian hearts and their importance in relation to human arrhythmogenic cardiomyopathies. We also emphasize the various plakophilin-2-positive plaques in AJs (coniunctiones adhaerentes connecting proliferatively active mesenchymally-derived cells, including interstitial cells of the heart and several soft tissue tumor cell types. Moreover, desmoplakin has also been recognized as a constituent of the plaques of the complexus adhaerentes connecting certain lymphatic endothelial cells. Finally, we emphasize the occurrence of the desmosomal transmembrane glycoprotein, desmoglein Dsg2, out of the context of any junction as dispersed cell surface molecules in certain types of melanoma cells and melanocytes. This broadening of our knowledge on the diversity of AJ structures indicates that it may still be too premature to close the textbook chapters on cell-cell junctions.

  19. The inner CSF–brain barrier: developmentally controlled access to the brain via intercellular junctions

    Science.gov (United States)

    Whish, Sophie; Dziegielewska, Katarzyna M.; Møllgård, Kjeld; Noor, Natassya M.; Liddelow, Shane A.; Habgood, Mark D.; Richardson, Samantha J.; Saunders, Norman R.

    2015-01-01

    In the adult the interface between the cerebrospinal fluid and the brain is lined by the ependymal cells, which are joined by gap junctions. These intercellular connections do not provide a diffusional restrain between the two compartments. However, during development this interface, initially consisting of neuroepithelial cells and later radial glial cells, is characterized by “strap” junctions, which limit the exchange of different sized molecules between cerebrospinal fluid and the brain parenchyma. Here we provide a systematic study of permeability properties of this inner cerebrospinal fluid-brain barrier during mouse development from embryonic day, E17 until adult. Results show that at fetal stages exchange across this barrier is restricted to the smallest molecules (286Da) and the diffusional restraint is progressively removed as the brain develops. By postnatal day P20, molecules the size of plasma proteins (70 kDa) diffuse freely. Transcriptomic analysis of junctional proteins present in the cerebrospinal fluid-brain interface showed expression of adherens junctional proteins, actins, cadherins and catenins changing in a development manner consistent with the observed changes in the permeability studies. Gap junction proteins were only identified in the adult as was claudin-11. Immunohistochemistry was used to localize at the cellular level some of the adherens junctional proteins of genes identified from transcriptomic analysis. N-cadherin, β - and α-catenin immunoreactivity was detected outlining the inner CSF-brain interface from E16; most of these markers were not present in the adult ependyma. Claudin-5 was present in the apical-most part of radial glial cells and in endothelial cells in embryos, but only in endothelial cells including plexus endothelial cells in adults. Claudin-11 was only immunopositive in the adult, consistent with results obtained from transcriptomic analysis. These results provide information about physiological, molecular

  20. The inner CSF–brain barrier: developmentally controlled access to the brain via intercellular junctions.

    Directory of Open Access Journals (Sweden)

    Norman Ruthven Saunders

    2015-02-01

    Full Text Available In the adult the interface between the cerebrospinal fluid (CSF and the brain is lined by the ependymal cells, which are joined by gap junctions. These intercellular connections do not provide a diffusional restrain between the two compartments. However during development this interface, initially consisting of neuroepithelial cells and later radial glial cells, is characterized by strap junctions, which limit the exchange of different sized molecules between CSF and the brain parenchyma. Here we provide a systematic study of permeability properties of this inner CSF-brain barrier during mouse development from embryonic day, E17 until adult. Results show that at fetal stages exchange across this barrier is restricted to the smallest molecules (286Da and the diffusional restraint is progressively removed as the brain develops. By postnatal day P20, molecules the size of plasma proteins (70kDa diffuse freely. Transcriptomic analysis of junctional proteins present in the CSF-brain interface showed expression of adherens junctional proteins, actins, cadherins and catenins changing in a development manner consistent with the observed changes in the permeability studies. Gap junction proteins were only identified in the adult as was claudin-11. Immunocytochemistry was used to localize at the cellular level some of the adherens junctional proteins of genes identified from transcriptomic analysis. N-cadherin, β– and α-catenin immunoreactivity was detected outlining the inner CSF-brain interface from E16; most of these markers were not present in the adult ependyma. Claudin-5 was present in the apical-most part of radial glial cells and in endothelial cells in embryos, but only in endothelial cells including plexus endothelial cells in adults. Claudin-11 was only immunopositive in the adult, consistent with results obtained from transcriptomic analysis. These results provide information about physiological, molecular and morphological

  1. Focal junctions retard lateral movement and disrupt fluid phase connectivity in the plasma membrane

    DEFF Research Database (Denmark)

    Vind-Kezunovic, D.; Wojewodzka, U.; Gniadecki, R.

    2008-01-01

    -p-cyclodextrin further decreased the recovery of DiI-C-18:0. We propose a model in which focal junctions impose lateral heterogeneity in the plasma membrane by entrapment of lipid microdomains between dense arrays of immobilized transmembrane molecules which can enmesh otherwise freely percolating L-d phase lipids. (c...... containing liquid-ordered (L-o) lipids. Indeed, values of maximal fluorescence recovery after photobleaching revealed that the long-range mobility of cholera toxin B subunit (CTB, marker of L-o) was similar to 1.5-fold retarded within the focal junctions compared to the surrounding membrane. However, 1...

  2. Focal junctions retard lateral movement and disrupt fluid phase connectivity in the plasma membrane

    DEFF Research Database (Denmark)

    Vind-Kezunovic, D.; Wojewodzka, U.; Gniadecki, R.

    2008-01-01

    ,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI-C-18:0), which specifically partitions to the liquid-disordered (L-d), non-raft phase, was also enriched in focal junctions and its mobility was slightly retarded. Cross-linking of GM(1) by CTB or raft aggregation by methyl......-p-cyclodextrin further decreased the recovery of DiI-C-18:0. We propose a model in which focal junctions impose lateral heterogeneity in the plasma membrane by entrapment of lipid microdomains between dense arrays of immobilized transmembrane molecules which can enmesh otherwise freely percolating L-d phase lipids. (c...

  3. [Functional connectivity of temporal parietal junction in online game addicts:a resting-state functional magnetic resonance imaging study].

    Science.gov (United States)

    Yuan, Ji; Qian, Ruobing; Lin, Bin; Fu, Xianming; Wei, Xiangpin; Weng, Chuanbo; Niu, Chaoshi; Wang, Yehan

    2014-02-11

    To explore the functions of temporal parietal junction (TPJ) as parts of attention networks in the pathogenesis of online game addiction using resting-state functional magnetic resonance imaging (fMRI). A total of 17 online game addicts (OGA) were recruited as OGA group and 17 healthy controls during the same period were recruited as CON group. The neuropsychological tests were performed for all of them to compare the inter-group differences in the results of Internet Addiction Test (IAT) and attention functions. All fMRI data were preprocessed after resting-state fMRI scanning. Then left and right TPJ were selected as regions of interest (ROIs) to calculate the linear correlation between TPJ and entire brain to compare the inter-group differences. Obvious differences existed between OGA group (71 ± 5 scores) and CON group (19 ± 7 scores) in the IAT results and attention function (P online game addicts showed decreased functional connectivity with bilateral ventromedial prefrontal cortex (VMPFC), bilateral hippocampal gyrus and bilateral amygdaloid nucleus, but increased functional connectivity with right cuneus.However, left TPJ demonstrated decreased functional connectivity with bilateral superior frontal gyrus and bilateral middle frontal gyrus, but increased functional connectivity with bilateral cuneus (P online game addicts.It suggests that TPJ is an important component of attention networks participating in the generation of online game addiction.

  4. Fabrication of magnetic tunnel junctions connected through a continuous free layer to enable spin logic devices

    Science.gov (United States)

    Wan, Danny; Manfrini, Mauricio; Vaysset, Adrien; Souriau, Laurent; Wouters, Lennaert; Thiam, Arame; Raymenants, Eline; Sayan, Safak; Jussot, Julien; Swerts, Johan; Couet, Sebastien; Rassoul, Nouredine; Babaei Gavan, Khashayar; Paredis, Kristof; Huyghebaert, Cedric; Ercken, Monique; Wilson, Christopher J.; Mocuta, Dan; Radu, Iuliana P.

    2018-04-01

    Magnetic tunnel junctions (MTJs) interconnected via a continuous ferromagnetic free layer were fabricated for spin torque majority gate (STMG) logic. The MTJs are biased independently and show magnetoelectric response under spin transfer torque. The electrical control of these devices paves the way to future spin logic devices based on domain wall (DW) motion. In particular, it is a significant step towards the realization of a majority gate. To our knowledge, this is the first fabrication of a cross-shaped free layer shared by several perpendicular MTJs. The fabrication process can be generalized to any geometry and any number of MTJs. Thus, this framework can be applied to other spin logic concepts based on magnetic interconnect. Moreover, it allows exploration of spin dynamics for logic applications.

  5. The role of apical cell-cell junctions and associated cytoskeleton in mechanotransduction.

    Science.gov (United States)

    Sluysmans, Sophie; Vasileva, Ekaterina; Spadaro, Domenica; Shah, Jimit; Rouaud, Florian; Citi, Sandra

    2017-04-01

    Tissues of multicellular organisms are characterised by several types of specialised cell-cell junctions. In vertebrate epithelia and endothelia, tight and adherens junctions (AJ) play critical roles in barrier and adhesion functions, and are connected to the actin and microtubule cytoskeletons. The interaction between junctions and the cytoskeleton is crucial for tissue development and physiology, and is involved in the molecular mechanisms governing cell shape, motility, growth and signalling. The machineries which functionally connect tight and AJ to the cytoskeleton comprise proteins which either bind directly to cytoskeletal filaments, or function as adaptors for regulators of the assembly and function of the cytoskeleton. In the last two decades, specific cytoskeleton-associated junctional molecules have been implicated in mechanotransduction, revealing the existence of multimolecular complexes that can sense mechanical cues and translate them into adaptation to tensile forces and biochemical signals. Here, we summarise the current knowledge about the machineries that link tight and AJ to actin filaments and microtubules, and the molecular basis for mechanotransduction at epithelial and endothelial AJ. © 2017 Société Française des Microscopies and Société de Biologie Cellulaire de France. Published by John Wiley & Sons Ltd.

  6. Zonula occludens-1 and -2 regulate apical cell structure and the zonula adherens cytoskeleton in polarized epithelia

    Science.gov (United States)

    Fanning, Alan S.; Van Itallie, Christina M.; Anderson, James M.

    2012-01-01

    The structure and function of both adherens (AJ) and tight (TJ) junctions are dependent on the cortical actin cytoskeleton. The zonula occludens (ZO)-1 and -2 proteins have context-dependent interactions with both junction types and bind directly to F-actin and other cytoskeletal proteins, suggesting ZO-1 and -2 might regulate cytoskeletal activity at cell junctions. To address this hypothesis, we generated stable Madin-Darby canine kidney cell lines depleted of both ZO-1 and -2. Both paracellular permeability and the localization of TJ proteins are disrupted in ZO-1/-2–depleted cells. In addition, immunocytochemistry and electron microscopy revealed a significant expansion of the perijunctional actomyosin ring associated with the AJ. These structural changes are accompanied by a recruitment of 1-phosphomyosin light chain and Rho kinase 1, contraction of the actomyosin ring, and expansion of the apical domain. Despite these changes in the apical cytoskeleton, there are no detectable changes in cell polarity, localization of AJ proteins, or the organization of the basal and lateral actin cytoskeleton. We conclude that ZO proteins are required not only for TJ assembly but also for regulating the organization and functional activity of the apical cytoskeleton, particularly the perijunctional actomyosin ring, and we speculate that these activities are relevant both to cellular organization and epithelial morphogenesis. PMID:22190737

  7. Vang-like protein 2 and rac1 interact to regulate adherens junctions

    Czech Academy of Sciences Publication Activity Database

    Lindqvist, M.; Horn, Z.; Bryja, Vítězslav; Schulte, G.; Papachristou, P.; Ajima, R.; Dyberg, C.; Arenas, E.; Yamaguchi, T.P.; Lagercrantz, H.; Ringstedt, T.

    2010-01-01

    Roč. 123, č. 3 (2010), s. 472-483 ISSN 0021-9533 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : cell adhesion * neurulation * PCP Subject RIV: BO - Biophysics Impact factor: 6.290, year: 2010

  8. Restricted tissue distribution of a 37-kD possible adherens junction protein

    OpenAIRE

    1992-01-01

    A major polypeptide of M(r) 37,000 was purified from a desmosome- enriched citric acid-insoluble pellet of pig tongue epithelium. The polypeptide was solubilized from the 4-M urea-insoluble pellet with 9 M urea, and extracts were separated by carboxymethyl cellulose and gel filtration chromatography. The 37-kD protein was obtained in milligram quantities as a single band on two-dimensional gels in 30% yield after 21-fold purification from the citric acid-insoluble fraction. The protein is not...

  9. Defective functional connectivity between posterior hypothalamus and regions of the diencephalic-mesencephalic junction in chronic cluster headache.

    Science.gov (United States)

    Ferraro, Stefania; Nigri, Anna; Bruzzone, Maria Grazia; Brivio, Luca; Proietti Cecchini, Alberto; Verri, Mattia; Chiapparini, Luisa; Leone, Massimo

    2018-01-01

    Objective We tested the hypothesis of a defective functional connectivity between the posterior hypothalamus and diencephalic-mesencephalic regions in chronic cluster headache based on: a) clinical and neuro-endocrinological findings in cluster headache patients; b) neuroimaging findings during cluster headache attacks; c) neuroimaging findings in drug-refractory chronic cluster headache patients improved after successful deep brain stimulation. Methods Resting state functional magnetic resonance imaging, associated with a seed-based approach, was employed to investigate the functional connectivity of the posterior hypothalamus in chronic cluster headache patients (n = 17) compared to age and sex-matched healthy subjects (n = 16). Random-effect analyses were performed to study differences between patients and controls in ipsilateral and contralateral-to-the-pain posterior hypothalamus functional connectivity. Results Cluster headache patients showed an increased functional connectivity between the ipsilateral posterior hypothalamus and a number of diencephalic-mesencephalic structures, comprising ventral tegmental area, dorsal nuclei of raphe, and bilateral substantia nigra, sub-thalamic nucleus, and red nucleus ( p cluster headache patients mainly involves structures that are part of (i.e. ventral tegmental area, substantia nigra) or modulate (dorsal nuclei of raphe, sub-thalamic nucleus) the midbrain dopaminergic systems. The midbrain dopaminergic systems could play a role in cluster headache pathophysiology and in particular in the chronicization process. Future studies are needed to better clarify if this finding is specific to cluster headache or if it represents an unspecific response to chronic pain.

  10. Nanotube junctions

    Science.gov (United States)

    Crespi, Vincent Henry; Cohen, Marvin Lou; Louie, Steven Gwon Sheng; Zettl, Alexander Karlwalter

    2003-01-01

    The present invention comprises a new nanoscale metal-semiconductor, semiconductor-semiconductor, or metal-metal junction, designed by introducing topological or chemical defects in the atomic structure of the nanotube. Nanotubes comprising adjacent sections having differing electrical properties are described. These nanotubes can be constructed from combinations of carbon, boron, nitrogen and other elements. The nanotube can be designed having different indices on either side of a junction point in a continuous tube so that the electrical properties on either side of the junction vary in a useful fashion. For example, the inventive nanotube may be electrically conducting on one side of a junction and semiconducting on the other side. An example of a semiconductor-metal junction is a Schottky barrier. Alternatively, the nanotube may exhibit different semiconductor properties on either side of the junction. Nanotubes containing heterojunctions, Schottky barriers, and metal-metal junctions are useful for microcircuitry.

  11. Tight Junction Disruption Induced by Type 3 Secretion System Effectors Injected by Enteropathogenic and Enterohemorrhagic Escherichia coli.

    Science.gov (United States)

    Ugalde-Silva, Paul; Gonzalez-Lugo, Octavio; Navarro-Garcia, Fernando

    2016-01-01

    The intestinal epithelium consists of a single cell layer, which is a critical selectively permeable barrier to both absorb nutrients and avoid the entry of potentially harmful entities, including microorganisms. Epithelial cells are held together by the apical junctional complexes, consisting of adherens junctions, and tight junctions (TJs), and by underlying desmosomes. TJs lay in the apical domain of epithelial cells and are mainly composed by transmembrane proteins such as occludin, claudins, JAMs, and tricellulin, that are associated with the cytoplasmic plaque formed by proteins from the MAGUK family, such as ZO-1/2/3, connecting TJ to the actin cytoskeleton, and cingulin and paracingulin connecting TJ to the microtubule network. Extracellular bacteria such as EPEC and EHEC living in the intestinal lumen inject effectors proteins directly from the bacterial cytoplasm to the host cell cytoplasm, where they play a relevant role in the manipulation of the eukaryotic cell functions by modifying or blocking cell signaling pathways. TJ integrity depends on various cell functions such as actin cytoskeleton, microtubule network for vesicular trafficking, membrane integrity, inflammation, and cell survival. EPEC and EHEC effectors target most of these functions. Effectors encoded inside or outside of locus of enterocyte effacement (LEE) disrupt the TJ strands. EPEC and EHEC exploit the TJ dynamics to open this structure, for causing diarrhea. EPEC and EHEC secrete effectors that mimic host proteins to manipulate the signaling pathways, including those related to TJ dynamics. In this review, we focus on the known mechanisms exploited by EPEC and EHEC effectors for causing TJ disruption.

  12. Electronic noise of superconducting tunnel junction detectors

    International Nuclear Information System (INIS)

    Jochum, J.; Kraus, H.; Gutsche, M.; Kemmather, B.; Feilitzsch, F. v.; Moessbauer, R.L.

    1994-01-01

    The optimal signal to noise ratio for detectors based on superconducting tunnel junctions is calculated and compared for the cases of a detector consisting of one single tunnel junction, as well as of series and of parallel connections of such tunnel junctions. The influence of 1 / f noise and its dependence on the dynamical resistance of tunnel junctions is discussed quantitatively. A single tunnel junction yields the minimum equivalent noise charge. Such a tunnel junction exhibits the best signal to noise ratio if the signal charge is independent of detector size. In case, signal charge increases with detector size, a parallel or a series connection of tunnel junctions would provide the optimum signal to noise ratio. The equivalent noise charge and the respective signal to noise ratio are deduced as functions of tunnel junction parameters such as tunneling time, quasiparticle lifetime, etc. (orig.)

  13. Gap junctions.

    Science.gov (United States)

    Goodenough, Daniel A; Paul, David L

    2009-07-01

    Gap junctions are aggregates of intercellular channels that permit direct cell-cell transfer of ions and small molecules. Initially described as low-resistance ion pathways joining excitable cells (nerve and muscle), gap junctions are found joining virtually all cells in solid tissues. Their long evolutionary history has permitted adaptation of gap-junctional intercellular communication to a variety of functions, with multiple regulatory mechanisms. Gap-junctional channels are composed of hexamers of medium-sized families of integral proteins: connexins in chordates and innexins in precordates. The functions of gap junctions have been explored by studying mutations in flies, worms, and humans, and targeted gene disruption in mice. These studies have revealed a wide diversity of function in tissue and organ biology.

  14. HMP-1/α-catenin promotes junctional mechanical integrity during morphogenesis.

    Directory of Open Access Journals (Sweden)

    Thanh Thi Kim Vuong-Brender

    Full Text Available Adherens junctions (AJs are key structures regulating tissue integrity and maintaining adhesion between cells. During morphogenesis, junctional proteins cooperate closely with the actomyosin network to drive cell movement and shape changes. How the junctions integrate the mechanical forces in space and in time during an in vivo morphogenetic event is still largely unknown, due to a lack of quantitative data. To address this issue, we inserted a functional Fluorescence Resonance Energy Transfer (FRET-based force biosensor within HMP-1/α-catenin of Caenorhabditis elegans. We find that the tension exerted on HMP-1 has a cell-specific distribution, is actomyosin-dependent, but is regulated differently from the tension on the actin cortex during embryonic elongation. By using time-lapse analysis of mutants and tissue-specific rescue experiments, we confirm the role of VAB-9/Claudin as an actin bundle anchor. Nevertheless, the tension exerted on HMP-1 did not increase in the absence of VAB-9/Claudin, suggesting that HMP-1 activity is not upregulated to compensate for loss of VAB-9. Our data indicate that HMP-1 does not modulate HMR-1/E-cadherin turnover, is required to recruit junctional actin but not stress fiber-like actin bundles. Altogether, our data suggest that HMP-1/α-catenin acts to promote the mechanical integrity of adherens junctions.

  15. Fractional order junctions

    Science.gov (United States)

    Machado, J. Tenreiro

    2015-01-01

    Gottfried Leibniz generalized the derivation and integration, extending the operators from integer up to real, or even complex, orders. It is presently recognized that the resulting models capture long term memory effects difficult to describe by classical tools. Leon Chua generalized the set of lumped electrical elements that provide the building blocks in mathematical models. His proposal of the memristor and of higher order elements broadened the scope of variables and relationships embedded in the development of models. This paper follows the two directions and proposes a new logical step, by generalizing the concept of junction. Classical junctions interconnect system elements using simple algebraic restrictions. Nevertheless, this simplistic approach may be misleading in the presence of unexpected dynamical phenomena and requires including additional "parasitic" elements. The novel γ -junction includes, as special cases, the standard series and parallel connections and allows a new degree of freedom when building models. The proposal motivates the search for experimental and real world manifestations of the abstract conjectures.

  16. Transmissible gastroenteritis virus and porcine epidemic diarrhoea virus infection induces dramatic changes in the tight junctions and microfilaments of polarized IPEC-J2 cells.

    Science.gov (United States)

    Zhao, Shanshan; Gao, Junkai; Zhu, Liqi; Yang, Qian

    2014-11-04

    Viral infection converts the normal constitution of a cell to optimise viral entry, replication, and virion production. These conversions contain alterations or disruptions of the tight and adherens junctions between cells as part of their pathogenesis, and reorganise cellular microfilaments that initiate, sustain and spread the viral infections and so on. Using porcine epidemic diarrhoea virus (PEDV), transmissible gastroenteritis virus (TGEV) and a model of normal intestinal epithelial cells (IPEC-J2), we researched the interaction between tight and adherens junctions and microfilaments of IPEC-J2 cells with these viruses. In our work, the results showed that IPEC-J2 cells were susceptible to TGEV and PEDV infection. And TGEV could impair the barrier integrity of IPEC-J2 cells at early stages of infection through down-regulating some proteins of tight and adherens junctions, while PEDV cloud cause a slight of damage in the integrity of epithelial barrier. In addition, they also could affect the microfilaments remodelling of IPEC-J2 cells, and the drug-interfered microfilaments could inhibit viral replication and release. Furthermore, PEDV+TGEV co-infection was more aggravating to damage of tight junctions and remodelling of microfilaments than their single infection. Finally, the PEDV and TGEV infection affected the MAPK pathway, and inhibition of MAPK pathway regulated the changes of tight junctions and microfilaments of cells. These studies provide a new insight from the perspective of the epithelial barrier and microfilaments into the pathogenesis of PEDV and TGEV. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. PCBS AND TIGHT JUNCTION EXPRESSION

    OpenAIRE

    Eum, Sung Yong; András, Ibolya E.; Couraud, Pierre-Olivier; Hennig, Bernhard; Toborek, Michal

    2008-01-01

    Polychlorinated biphenyl (PCB) congeners exhibit a broad range of adverse biological effects including neurotoxicity. The mechanisms by which PCBs cause neurotoxic effects are still not completely understood. The blood-brain barrier (BBB) is a physical and metabolic barrier separating brain microenvironment from the peripheral circulation and is mainly composed of endothelial cells connected by tight junctions. We examined the effects of several highly-chlorinated PCB congeners on expression ...

  18. CD151 promotes α3β1 integrin-dependent organization of carcinoma cell junctions and restrains collective cell invasion.

    Science.gov (United States)

    Zevian, Shannin C; Johnson, Jessica L; Winterwood, Nicole E; Walters, Katherine S; Herndon, Mary E; Henry, Michael D; Stipp, Christopher S

    2015-01-01

    Integrins function in collective migration both as major receptors for extracellular matrix and by crosstalk to adherens junctions. Despite extensive research, important questions remain about how integrin signaling mechanisms are integrated into collective migration programs. Tetraspanins form cell surface complexes with a subset of integrins and thus are good candidates for regulating the balance of integrin functional inputs into cell-matrix and cell-cell interactions. For example, tetraspanin CD151 directly associates with α3β1 integrin in carcinoma cells and promotes rapid α3β1-dependent single cell motility, but CD151 also promotes organized adherens junctions and restrains collective carcinoma cell migration on 2D substrates. However, the individual roles of CD151s integrin partners in CD151s pro-junction activity in carcinoma cells were not well understood. Here we find that CD151 promotes organized carcinoma cell junctions via α3β1 integrin, by a mechanism that requires the a3b1 ligand, laminin-332. Loss of CD151 promotes collective 3D invasion and growth in vitro and in vivo, and the enhanced invasion of CD151-silenced cells is α3 integrin dependent, suggesting that CD151 can regulate the balance between α3β1s pro-junction and pro-migratory activities in collective invasion. An analysis of human cancer cases revealed that changes in CD151 expression can be linked to either better or worse clinical outcomes depending on context, including potentially divergent roles for CD151 in different subsets of breast cancer cases. Thus, the role of the CD151-α3β1 complex in carcinoma progression is context dependent, and may depend on the mode of tumor cell invasion.

  19. Valley dependent transport in graphene L junction

    Science.gov (United States)

    Chan, K. S.

    2018-05-01

    We studied the valley dependent transport in graphene L junctions connecting an armchair lead and a zigzag lead. The junction can be used in valleytronic devices and circuits. Electrons injected from the armchair lead into the junction is not valley polarized, but they can become valley polarized in the zigzag lead. There are Fermi energies, where the current in the zigzag lead is highly valley polarized and the junction is an efficient generator of valley polarized current. The features of the valley polarized current depend sensitively on the widths of the two leads, as well as the number of dimers in the armchair lead, because this number has a sensitive effect on the band structure of the armchair lead. When an external potential is applied to the junction, the energy range with high valley polarization is enlarged enhancing its function as a generator of highly valley polarized current. The scaling behavior found in other graphene devices is also found in L junctions, which means that the results presented here can be extended to junctions with larger dimensions after appropriate scaling of the energy.

  20. Overexpression of galectin-7 in mouse epidermis leads to loss of cell junctions and defective skin repair.

    Directory of Open Access Journals (Sweden)

    Gaëlle Gendronneau

    Full Text Available The proteins of the galectin family are implicated in many cellular processes, including cell interactions, polarity, intracellular trafficking, and signal transduction. In human and mouse, galectin-7 is almost exclusively expressed in stratified epithelia, notably in the epidermis. Galectin-7 expression is also altered in several human tumors of epithelial origin. This study aimed at dissecting the consequences of galectin-7 overexpression on epidermis structure and functions in vivo.We established transgenic mice specifically overexpressing galectin-7 in the basal epidermal keratinocytes and analyzed the consequences on untreated skin and after UVB irradiation or mechanical injury.The intercellular cohesion of the epidermis is impaired in transgenic animals, with gaps developing between adjacent keratinocytes, associated with loss of adherens junctions. The epidermal architecture is aberrant with perturbations in the multilayered cellular organisation of the tissue, and structural defects in the basement membrane. These transgenic animals displayed a reduced re-epithelialisation potential following superficial wound, due to a defective collective migration of keratinocytes. Finally, a single mild dose of UVB induced an abnormal apoptotic response in the transgenic epidermis.These results indicate that an excess of galectin-7 leads to a destabilisation of adherens junctions associated with defects in epidermal repair. As this phenotype shares similarities with that of galectin-7 null mutant mice, we conclude that a critical level of this protein is required for maintaining proper epidermal homeostasis. This study brings new insight into the mode of action of galectins in normal and pathological situations.

  1. Overexpression of galectin-7 in mouse epidermis leads to loss of cell junctions and defective skin repair.

    Science.gov (United States)

    Gendronneau, Gaëlle; Sanii, Sadaf; Dang, Tien; Deshayes, Frédérique; Delacour, Delphine; Pichard, Evelyne; Advedissian, Tamara; Sidhu, Sukhvinder S; Viguier, Mireille; Magnaldo, Thierry; Poirier, Francoise

    2015-01-01

    The proteins of the galectin family are implicated in many cellular processes, including cell interactions, polarity, intracellular trafficking, and signal transduction. In human and mouse, galectin-7 is almost exclusively expressed in stratified epithelia, notably in the epidermis. Galectin-7 expression is also altered in several human tumors of epithelial origin. This study aimed at dissecting the consequences of galectin-7 overexpression on epidermis structure and functions in vivo. We established transgenic mice specifically overexpressing galectin-7 in the basal epidermal keratinocytes and analyzed the consequences on untreated skin and after UVB irradiation or mechanical injury. The intercellular cohesion of the epidermis is impaired in transgenic animals, with gaps developing between adjacent keratinocytes, associated with loss of adherens junctions. The epidermal architecture is aberrant with perturbations in the multilayered cellular organisation of the tissue, and structural defects in the basement membrane. These transgenic animals displayed a reduced re-epithelialisation potential following superficial wound, due to a defective collective migration of keratinocytes. Finally, a single mild dose of UVB induced an abnormal apoptotic response in the transgenic epidermis. These results indicate that an excess of galectin-7 leads to a destabilisation of adherens junctions associated with defects in epidermal repair. As this phenotype shares similarities with that of galectin-7 null mutant mice, we conclude that a critical level of this protein is required for maintaining proper epidermal homeostasis. This study brings new insight into the mode of action of galectins in normal and pathological situations.

  2. 2,2', 4,4',5,5'-Hexachlorobiphenyl (PCB 153) induces degradation of adherens junction proteins and inhibits beta-catenin-dependent transcription in liver epithelial cells

    Czech Academy of Sciences Publication Activity Database

    Šimečková, P.; Vondráček, J.; Procházková, J.; Kozubík, Alois; Krčmář, P.; Machala, M.

    2009-01-01

    Roč. 260, 1-3 (2009), s. 104-111 ISSN 0300-483X R&D Projects: GA ČR(CZ) GA524/06/0517 Grant - others:GA ČR(CZ) GA524/09/1337 Program:GA Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : polychlorinated biphenyls * E-cadherin * beta-catenin Subject RIV: BO - Biophysics Impact factor: 3.241, year: 2009

  3. Molecular electronic junction transport

    DEFF Research Database (Denmark)

    Solomon, Gemma C.; Herrmann, Carmen; Ratner, Mark

    2012-01-01

    Whenasinglemolecule,oracollectionofmolecules,isplacedbetween two electrodes and voltage is applied, one has a molecular transport junction. We discuss such junctions, their properties, their description, and some of their applications. The discussion is qualitative rather than quantitative......, and focuses on mechanism, structure/function relations, regimes and mechanisms of transport, some molecular regularities, and some substantial challenges facing the field. Because there are many regimes and mechanisms in transport junctions, we will discuss time scales, geometries, and inelastic scattering...

  4. ‘Gap Junctions and Cancer: Communicating for 50 Years’

    Science.gov (United States)

    Aasen, Trond; Mesnil, Marc; Naus, Christian C.; Lampe, Paul D.; Laird, Dale W.

    2017-01-01

    Fifty years ago, tumour cells were found to lack electrical coupling, leading to the hypothesis that loss of direct intercellular communication is commonly associated with cancer onset and progression. Subsequent studies linked this phenomenon to gap junctions composed of connexin proteins. While many studies support the notion that connexins are tumour suppressors, recent evidence suggests that, in some tumour types, they may facilitate specific stages of tumour progression through both junctional and non-junctional signalling pathways. This Timeline article highlights the milestones connecting gap junctions to cancer, and underscores important unanswered questions, controversies and therapeutic opportunities in the field. PMID:27782134

  5. Unique cell type-specific junctional complexes in vascular endothelium of human and rat liver sinusoids.

    Directory of Open Access Journals (Sweden)

    Cyrill Géraud

    Full Text Available Liver sinusoidal endothelium is strategically positioned to control access of fluids, macromolecules and cells to the liver parenchyma and to serve clearance functions upstream of the hepatocytes. While clearance of macromolecular debris from the peripheral blood is performed by liver sinusoidal endothelial cells (LSECs using a delicate endocytic receptor system featuring stabilin-1 and -2, the mannose receptor and CD32b, vascular permeability and cell trafficking are controlled by transcellular pores, i.e. the fenestrae, and by intercellular junctional complexes. In contrast to blood vascular and lymphatic endothelial cells in other organs, the junctional complexes of LSECs have not yet been consistently characterized in molecular terms. In a comprehensive analysis, we here show that LSECs express the typical proteins found in endothelial adherens junctions (AJ, i.e. VE-cadherin as well as α-, β-, p120-catenin and plakoglobin. Tight junction (TJ transmembrane proteins typical of endothelial cells, i.e. claudin-5 and occludin, were not expressed by rat LSECs while heterogenous immunreactivity for claudin-5 was detected in human LSECs. In contrast, junctional molecules preferentially associating with TJ such as JAM-A, B and C and zonula occludens proteins ZO-1 and ZO-2 were readily detected in LSECs. Remarkably, among the JAMs JAM-C was considerably over-expressed in LSECs as compared to lung microvascular endothelial cells. In conclusion, we show here that LSECs form a special kind of mixed-type intercellular junctions characterized by co-occurrence of endothelial AJ proteins, and of ZO-1 and -2, and JAMs. The distinct molecular architecture of the intercellular junctional complexes of LSECs corroborates previous ultrastructural findings and provides the molecular basis for further analyses of the endothelial barrier function of liver sinusoids under pathologic conditions ranging from hepatic inflammation to formation of liver metastasis.

  6. Gap junctions-guards of excitability

    DEFF Research Database (Denmark)

    Stroemlund, Line Waring; Jensen, Christa Funch; Qvortrup, Klaus

    2015-01-01

    Cardiomyocytes are connected by mechanical and electrical junctions located at the intercalated discs (IDs). Although these structures have long been known, it is becoming increasingly clear that their components interact. This review describes the involvement of the ID in electrical disturbances...... of the heart and focuses on the role of the gap junctional protein connexin 43 (Cx43). Current evidence shows that Cx43 plays a crucial role in organizing microtubules at the intercalated disc and thereby regulating the trafficking of the cardiac sodium channel NaV1.5 to the membrane....

  7. Relaxation oscillation logic in Josephson junction circuits

    International Nuclear Information System (INIS)

    Fulton, T.A.

    1981-01-01

    A dc powered, self-resetting Josephson junction logic circuit relying on relaxation oscillations is described. A pair of Josephson junction gates are connected in series, a first shunt is connected in parallel with one of the gates, and a second shunt is connected in parallel with the series combination of gates. The resistance of the shunts and the dc bias current bias the gates so that they are capable of undergoing relaxation oscillations. The first shunt forms an output line whereas the second shunt forms a control loop. The bias current is applied to the gates so that, in the quiescent state, the gate in parallel with the second shunt is at V O, and the other gate is undergoing relaxation oscillations. By controlling the state of the first gate with the current in the output loop of another identical circuit, the invert function is performed

  8. Quantum Junction Solar Cells

    KAUST Repository

    Tang, Jiang

    2012-09-12

    Colloidal quantum dot solids combine convenient solution-processing with quantum size effect tuning, offering avenues to high-efficiency multijunction cells based on a single materials synthesis and processing platform. The highest-performing colloidal quantum dot rectifying devices reported to date have relied on a junction between a quantum-tuned absorber and a bulk material (e.g., TiO 2); however, quantum tuning of the absorber then requires complete redesign of the bulk acceptor, compromising the benefits of facile quantum tuning. Here we report rectifying junctions constructed entirely using inherently band-aligned quantum-tuned materials. Realizing these quantum junction diodes relied upon the creation of an n-type quantum dot solid having a clean bandgap. We combine stable, chemically compatible, high-performance n-type and p-type materials to create the first quantum junction solar cells. We present a family of photovoltaic devices having widely tuned bandgaps of 0.6-1.6 eV that excel where conventional quantum-to-bulk devices fail to perform. Devices having optimal single-junction bandgaps exhibit certified AM1.5 solar power conversion efficiencies of 5.4%. Control over doping in quantum solids, and the successful integration of these materials to form stable quantum junctions, offers a powerful new degree of freedom to colloidal quantum dot optoelectronics. © 2012 American Chemical Society.

  9. ROCK2 primes the endothelium for vascular hyperpermeability responses by raising baseline junctional tension

    Science.gov (United States)

    Beckers, Cora M.L.; Knezevic, Nebojsa; Valent, Erik T.; Tauseef, Mohammad; Krishnan, Ramaswamy; Rajendran, Kavitha; Hardin, C. Corey; Aman, Jurjan; van Bezu, Jan; Sweetnam, Paul; van Hinsbergh, Victor W.M.; Mehta, Dolly; van Nieuw Amerongen, Geerten P.

    2015-01-01

    Rho kinase mediates the effects of inflammatory permeability factors by increasing actomyosin-generated traction forces on endothelial adherens junctions, resulting in disassembly of intercellular junctions and increased vascular leakage. In vitro, this is accompanied by the Rho kinase-driven formation of prominent radial F-actin fibers, but the in vivo relevance of those F-actin fibers has been debated, suggesting other Rho kinase-mediated events to occur in vascular leak. Here, we delineated the contributions of the highly homologous isoforms of Rho kinase (ROCK1 and ROCK2) to vascular hyperpermeability responses. We show that ROCK2, rather than ROCK1 is the critical Rho kinase for regulation of thrombin receptor-mediated vascular permeability. Novel traction force mapping in endothelial monolayers, however, shows that ROCK2 is not required for the thrombin-induced force enhancements. Rather, ROCK2 is pivotal to baseline junctional tension as a novel mechanism by which Rho kinase primes the endothelium for hyperpermeability responses, independent from subsequent ROCK1-mediated contractile stress-fiber formation during the late phase of the permeability response. PMID:25869521

  10. Electron and Phonon Transport in Molecular Junctions

    DEFF Research Database (Denmark)

    Li, Qian

    transmission at the Fermi energy. We propose and analyze a way of using π   stacking to design molecular junctions to control heat transport. We develop a simple model system to identify optimal parameter regimes and then use density functional theory (DFT) to extract model parameters for a number of specific......Molecular electronics provide the possibility to investigate electron and phonon transport at the smallest imaginable scale, where quantum effects can be investigated and exploited directly in the design. In this thesis, we study both electron transport and phonon transport in molecular junctions....... The system we are interested in here are π-stacked molecules connected with two semi-infinite leads. π-stacked aromatic rings, connected via π-π electronic coupling, provides a rather soft mechanical bridge while maintaining high electronic conductivity. We investigate electron transport...

  11. Functional tight junction barrier localizes in the second layer of the stratum granulosum of human epidermis.

    Science.gov (United States)

    Yoshida, Kazue; Yokouchi, Mariko; Nagao, Keisuke; Ishii, Ken; Amagai, Masayuki; Kubo, Akiharu

    2013-08-01

    Mammalian epidermis has two diffusion barriers, the stratum corneum (SC) and tight junctions (TJs). We reported previously that a single living cell layer exists between the SC and TJ-forming keratinocytes in mice; however, the exact location of the TJ barrier in human epidermis has not been defined. To investigate the precise distribution of epidermal TJs in relation to various cell-cell junction proteins and the SC and to clarify the barrier function of TJs against macromolecules in human skin. The localization of various junctional proteins was investigated in human skin sections and in the roofs of bullae formed by ex vivo exfoliative toxin (ET) treatment in three dimensions. ET and single-chain variable fragments (scFv) against desmoglein 1 were used as large diffusion probes. Human stratum granulosum (SG) cells have a distinct distribution of TJ, adherens junction, and desmosome proteins in the uppermost three layers (SG1-SG3 from the surface inward). Ex vivo injection of ET or scFv demonstrated that only SG2-SG2 junctions function as a TJ barrier, limiting the inside-out diffusion of these proteins. The roofs of bullae formed by ex vivo ET treatment consisted of SC, SG1 cells, and TJ-forming SG2 cells, probably mimicking bulla formation in bullous impetigo. Human epidermis has three SG cell layers with distinct properties just beneath the SC, of which only SG2 cells have functional TJs. Our results suggest that human epidermal TJs between SG2 cells form a paracellular diffusion barrier against soluble proteins, including immunoglobulins and bacterial toxins. Copyright © 2013 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.

  12. Electronic Properties of Carbon Nanotubes and Junctions

    Science.gov (United States)

    Anantram, M. P.; Han, Jie; Yang, Liu; Govindan, T. R.; Jaffe, R.; Saini, Subhash (Technical Monitor)

    1998-01-01

    Metallic and semiconducting Single Wall Carbon Nanotubes (CNT) have recently been characterized using scanning tunneling microscopy (STM) and the manipulation of individual CNT has been demonstrated. These developments make the prospect of using CNT as molecular wires and possibly as electronic devices an even more interesting one. We have been modeling various electronic properties such as the density of states and the transmission coefficient of CNT wires and junctions. These studies involve first calculating the stability of junctions using molecular dynamics simulations and then calculating the electronic properties using a pi-electron tight binding Hamiltonian. We have developed the expertise to calculate the electronic properties of both finite-sized CNT and CNT systems with semi-infinite boundary conditions. In this poster, we will present an overview of some of our results. The electronic application of CNT that is most promising at this time is their use as molecular wires. The conductance can however be greatly reduced because of reflection due to defects and contacts. We have modeled the transmission through CNT in the presence of two types of defects: weak uniform disorder and strong isolated scatterers. We find that the conductance is affected in significantly different manners due to these defects Junctions of CNT have also been imaged using STM. This makes it essential to derive rules for the formation of junctions between tubes of different chirality, study their relative energies and electronic properties. We have generalized the rules for connecting two different CNT and have calculated the transmission and density of states through CNT junctions. Metallic and semiconducting CNT can be joined to form a stable junction and their current versus voltage characteristics are asymmetric. CNT are deformed by the application of external forces including interactions with a substrate or other CNT. In many experiments, these deformation are expected to

  13. Junction-FET dosimeter

    International Nuclear Information System (INIS)

    Tomimasu, T.; Yamazaki, T.

    1976-01-01

    The performance of a new junction-FET dosimeter and its application to the beam profile measurement are presented. One of the two junction FET's making up an astable multivibrator is used as a small-size (approx.0.4x0.4 mm) high-level dose detector. The irradiated dose can be estimated by the amount of the decrease of the oscillator period of the multivibrator. The distinct advantages in its small size and superior resistive property to radiation effect enable us to measure the cross-sectional profile of the electron beam from a linac with high spatial resolution of about 0.4 mm

  14. Tunable Nitride Josephson Junctions.

    Energy Technology Data Exchange (ETDEWEB)

    Missert, Nancy A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Henry, Michael David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lewis, Rupert M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Howell, Stephen W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wolfley, Steven L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Brunke, Lyle Brent [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wolak, Matthaeus [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-12-01

    We have developed an ambient temperature, SiO2/Si wafer - scale process for Josephson junctions based on Nb electrodes and Ta x N barriers with tunable electronic properties. The films are fabricated by magnetron sputtering. The electronic properties of the TaxN barriers are controlled by adjusting the nitrogen flow during sputtering. This technology offers a scalable alternative to the more traditional junctions based on AlOx barriers for low - power, high - performance computing.

  15. Doped semiconductor nanocrystal junctions

    Energy Technology Data Exchange (ETDEWEB)

    Borowik, Ł.; Mélin, T., E-mail: thierry.melin@isen.iemn.univ-lille1.fr [Institut d’Electronique, de Microélectronique et de Nanotechnologie, CNRS-UMR8520, Avenue Poincaré, F-59652 Villeneuve d’Ascq (France); Nguyen-Tran, T.; Roca i Cabarrocas, P. [Laboratoire de Physique des Interfaces et des Couches Minces, CNRS-UMR7647, Ecole Polytechnique, F-91128 Palaiseau (France)

    2013-11-28

    Semiconductor junctions are the basis of electronic and photovoltaic devices. Here, we investigate junctions formed from highly doped (N{sub D}≈10{sup 20}−10{sup 21}cm{sup −3}) silicon nanocrystals (NCs) in the 2–50 nm size range, using Kelvin probe force microscopy experiments with single charge sensitivity. We show that the charge transfer from doped NCs towards a two-dimensional layer experimentally follows a simple phenomenological law, corresponding to formation of an interface dipole linearly increasing with the NC diameter. This feature leads to analytically predictable junction properties down to quantum size regimes: NC depletion width independent of the NC size and varying as N{sub D}{sup −1/3}, and depleted charge linearly increasing with the NC diameter and varying as N{sub D}{sup 1/3}. We thus establish a “nanocrystal counterpart” of conventional semiconductor planar junctions, here however valid in regimes of strong electrostatic and quantum confinements.

  16. Characterization of cytoskeletal and junctional proteins expressed by cells cultured from human arachnoid granulation tissue

    Directory of Open Access Journals (Sweden)

    Mehta Bhavya C

    2005-10-01

    the in vitro culture of arachnoidal cells grown from human AG tissue. We demonstrated that these cells in vitro continue to express some of the cytoskeletal and junctional proteins characterized previously in human AG tissue, such as proteins involved in the formation of gap junctions, desmosomes, epithelial specific adherens junctions, as well as tight junctions. These junctional proteins in particular may be important in allowing these arachnoidal cells to regulate CSF outflow.

  17. αT-catenin in restricted brain cell types and its potential connection to autism.

    Science.gov (United States)

    Folmsbee, Stephen Sai; Wilcox, Douglas R; Tyberghein, Koen; De Bleser, Pieter; Tourtellotte, Warren G; van Hengel, Jolanda; van Roy, Frans; Gottardi, Cara J

    2016-01-01

    Recent genetic association studies have linked the cadherin-based adherens junction protein alpha-T-catenin (αT-cat, CTNNA3) with the development of autism. Where αT-cat is expressed in the brain, and how its loss could contribute to this disorder, are entirely unknown. We used the αT-cat knockout mouse to examine the localization of αT-cat in the brain, and we used histology and immunofluorescence analysis to examine the neurobiological consequences of its loss. We found that αT-cat comprises the ependymal cell junctions of the ventricles of the brain, and its loss led to compensatory upregulation of αE-cat expression. Notably, αT-cat was not detected within the choroid plexus, which relies on cell junction components common to typical epithelial cells. While αT-cat was not detected in neurons of the cerebral cortex, it was abundantly detected within neuronal structures of the molecular layer of the cerebellum. Although αT-cat loss led to no overt differences in cerebral or cerebellar structure, RNA-sequencing analysis from wild type versus knockout cerebella identified a number of disease-relevant signaling pathways associated with αT-cat loss, such as GABA-A receptor activation. These findings raise the possibility that the genetic associations between αT-cat and autism may be due to ependymal and cerebellar defects, and highlight the potential importance of a seemingly redundant adherens junction component to a neurological disorder.

  18. Simulation of the performance of a five-junction array for 780-950 GHz

    CERN Document Server

    Shi, S C; Noguchi, T

    2002-01-01

    The performance of a five-junction (Nb/AlO sub x /Nb) array is characterized in the frequency range of 780-950 GHz for different wiring and ground layers of the thin-film microstrip lines of the junction tuning inductance and the associated impedance transformer. Three kinds of thin films (i.e., Nb, Al and NbTiN) are taken for this investigation. The individual SIS junctions of the five-junction array have an area of 1 mu m sup 2 and a critical current density of 10 kA cm sup - sup 2. The performance of parallel-connected twin junctions, which have the same junction parameters as those of the five-junction array, is also studied for comparison.

  19. The computational design of junctions between carbon nanotubes and graphene nanoribbons

    International Nuclear Information System (INIS)

    Li Yefei; Li Bingrui; Zhang Haoli

    2009-01-01

    Using first-principles density functional theory calculations, various junction models constructed from different carbon nanotube and graphene nanoribbon units via covalent linkage have been envisioned. These models consist of linear, T- and H-shaped junctions within the connection modes between carbon nanotube and graphene nanoribbon units. The electronic transport properties of different junctions have been systematically investigated by using the non-equilibrium Green's function. The simulation results suggested that the proposed models are promising for future applications in novel nanoelectronics.

  20. Gas-liquid flow splitting in T-junction with inclined lateral arm

    Science.gov (United States)

    Yang, Le-le; Liu, Shuo; Li, Hua; Zhang, Jian; Wu, Ying-xiang; Xu, Jing-yu

    2018-02-01

    This paper studies the gas-liquid flow splitting in T-junction with inclined lateral arm. The separation mechanism of the T-junction is related to the pressure distribution in the T-junction. It is shown that the separation efficiency strongly depends on the inclination angle, when the angle ranges from 0° to 30°, while not so strongly for angles in the range from 30° to 90° Increasing the number of connecting tubes is helpful for the gas-liquid separation, and under the present test conditions, with four connecting tubes, a good separation performance can be achieved. Accordingly, a multi-tube Y-junction separator with four connecting tubes is designed for the experimental investigation. A good agreement between the simulated and measured data shows that there is an optimal split ratio to achieve the best performance for the multi-tube Y-junction separator.

  1. Contour junctions defined by dynamic image deformations enhance perceptual transparency.

    Science.gov (United States)

    Kawabe, Takahiro; Nishida, Shin'ya

    2017-11-01

    The majority of work on the perception of transparency has focused on static images with luminance-defined contour junctions, but recent work has shown that dynamic image sequences with dynamic image deformations also provide information about transparency. The present study demonstrates that when part of a static image is dynamically deformed, contour junctions at which deforming and nondeforming contours are connected facilitate the deformation-based perception of a transparent layer. We found that the impression of a transparent layer was stronger when a dynamically deforming area was adjacent to static nondeforming areas than when presented alone. When contour junctions were not formed at the dynamic-static boundaries, however, the impression of a transparent layer was not facilitated by the presence of static surrounding areas. The effect of the deformation-defined junctions was attenuated when the spatial pattern of luminance contrast at the junctions was inconsistent with the perceived transparency related to luminance contrast, while the effect did not change when the spatial luminance pattern was consistent with it. In addition, the results showed that contour completions across the junctions were required for the perception of a transparent layer. These results indicate that deformation-defined junctions that involve contour completion between deforming and nondeforming regions enhance the perception of a transparent layer, and that the deformation-based perceptual transparency can be promoted by the simultaneous presence of appropriately configured luminance and contrast-other features that can also by themselves produce the sensation of perceiving transparency.

  2. Gap junctions in developing thalamic and neocortical neuronal networks

    NARCIS (Netherlands)

    Niculescu, Dragos; Lohmann, C.

    2014-01-01

    The presence of direct, cytoplasmatic, communication between neurons in the brain of vertebrates has been demonstrated a long time ago. These gap junctions have been characterized in many brain areas in terms of subunit composition, biophysical properties, neuronal connectivity patterns, and

  3. Preparation of CN /Carbon Nanotube Intramolecular Junctions by ...

    African Journals Online (AJOL)

    NICO

    middle during the growth process of the tubes. The phenomenon has been observed previously in preparing CNx/C intra- molecular junctions via the CVD method by pyrolysis of ferrocene and melamine.23 It should be pointed out that no catalyst is necessary for connecting CNx and MWCNT segments. As shown in Figs.

  4. INVESTIGATION OF InGaN/Si DOUBLE JUNCTION TANDEM ...

    African Journals Online (AJOL)

    2012-12-31

    Dec 31, 2012 ... Photovoltaic (PV) tandem cells have been widely demonstrated in recent years as an effective pathway ... In this paper, we have modelled the photovoltaic conversion efficiency of series-connected, two-junction ... The equation relating the bandgap energy to the mole fraction x is given by [6,7] as: Eg(x)= x ...

  5. Cementoenamel junction: An insight

    Directory of Open Access Journals (Sweden)

    Kharidi Laxman Vandana

    2014-01-01

    Full Text Available The location and nature of cemento-enamel junction (CEJ are more than descriptive terms used simply to describe some aspects of tooth morphology; however, CEJ gains a lot of clinical significance due to various measurements dependent on it. It may be necessary to determine the location and pathological changes occurring at CEJ to make a diagnosis and treat diseases pertaining to epithelial attachment and gingival margin. However, the information related to CEJ is not discussed commonly. Hence, the present review paper provides an insight on CEJ in both primary and permanent dentition.

  6. The human myotendinous junction

    DEFF Research Database (Denmark)

    Knudsen, A B; Larsen, M; Mackey, Abigail

    2015-01-01

    The myotendinous junction (MTJ) is a specialized structure in the musculotendinous system, where force is transmitted from muscle to tendon. Animal models have shown that the MTJ takes form of tendon finger-like processes merging with muscle tissue. The human MTJ is largely unknown and has never...... been described in three dimensions (3D). The aim of this study was to describe the ultrastructure of the human MTJ and render 3D reconstructions. Fourteen subjects (age 25 ± 3 years) with isolated injury of the anterior cruciate ligament (ACL), scheduled for reconstruction with a semitendinosus...

  7. CD44 variant, but not standard CD44 isoforms, mediate disassembly of endothelial VE-cadherin junction on metastatic melanoma cells.

    Science.gov (United States)

    Zhang, Pu; Fu, Changliang; Bai, Huiyuan; Song, Erqun; Dong, Cheng; Song, Yang

    2014-12-20

    Loss of endothelial adherens junctions is involved in tumor metastasis. Here, we demonstrate that, in the metastatic Lu1205 melanoma cells, expression of the CD44 variant CD44v8-v10 induced junction disassembly and vascular endothelial (VE)-cadherin phosphorylation at Y658 and Y731. Short interfering RNA (siRNA)-mediated CD44 knockdown or sialic acid cleavage reversed these effects. Moreover, microspheres coated with recombinant CD44v8-v10 promoted endothelial junction disruption. Overexpression of CD44v8-v10 but not of standard CD44 (CD44s) promoted gap formation in the non-metastatic WM35 melanoma cells, whereas CD44 knockdown or neuraminidase treatment dramatically diminished melanoma transendothelial migration. Endothelial cells transfected with the phosphomimetic VE-cadherin mutant Y658E supported transmigration of CD44-silenced Lu1205 cells. Our findings imply that CD44 variant isoform (CD44v) but not CD44s regulates endothelial junction loss, promoting melanoma extravasation. Copyright © 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  8. Neuromuscular junction disorders.

    Science.gov (United States)

    Verschuuren, Jan; Strijbos, Ellen; Vincent, Angela

    2016-01-01

    Diseases of the neuromuscular junction comprise a wide range of disorders. Antibodies, genetic mutations, specific drugs or toxins interfere with the number or function of one of the essential proteins that control signaling between the presynaptic nerve ending and the postsynaptic muscle membrane. Acquired autoimmune disorders of the neuromuscular junction are the most common and are described here. In myasthenia gravis, antibodies to acetylcholine receptors or to proteins involved in receptor clustering, particularly muscle-specific kinase, cause direct loss of acetylcholine receptors or interfere with the agrin-induced acetylcholine receptor clustering necessary for efficient neurotransmission. In the Lambert-Eaton myasthenic syndrome (LEMS), loss of the presynaptic voltage-gated calcium channels results in reduced release of the acetylcholine transmitter. The conditions are generally recognizable clinically and the diagnosis confirmed by serologic testing and electromyography. Screening for thymomas in myasthenia or small cell cancer in LEMS is important. Fortunately, a wide range of symptomatic treatments, immunosuppressive drugs, or other immunomodulating therapies is available. Future research is directed to understanding the pathogenesis, discovering new antigens, and trying to develop disease-specific treatments. © 2016 Elsevier B.V. All rights reserved.

  9. Manipulating connectivity and electrical conductivity in metallic nanowire networks.

    Science.gov (United States)

    Nirmalraj, Peter N; Bellew, Allen T; Bell, Alan P; Fairfield, Jessamyn A; McCarthy, Eoin K; O'Kelly, Curtis; Pereira, Luiz F C; Sorel, Sophie; Morosan, Diana; Coleman, Jonathan N; Ferreira, Mauro S; Boland, John J

    2012-11-14

    Connectivity in metallic nanowire networks with resistive junctions is manipulated by applying an electric field to create materials with tunable electrical conductivity. In situ electron microscope and electrical measurements visualize the activation and evolution of connectivity within these networks. Modeling nanowire networks, having a distribution of junction breakdown voltages, reveals universal scaling behavior applicable to all network materials. We demonstrate how local connectivity within these networks can be programmed and discuss material and device applications.

  10. Mixing in T-junctions

    NARCIS (Netherlands)

    Kok, Jacobus B.W.; van der Wal, S.

    1996-01-01

    The transport processes that are involved in the mixing of two gases in a T-junction mixer are investigated. The turbulent flow field is calculated for the T-junction with the k- turbulence model by FLOW3D. In the mathematical model the transport of species is described with a mixture fraction

  11. Fluid Flow at Branching Junctions

    OpenAIRE

    Sochi, Taha

    2013-01-01

    The flow of fluids at branching junctions plays important kinematic and dynamic roles in most biological and industrial flow systems. The present paper highlights some key issues related to the flow of fluids at these junctions with special emphasis on the biological flow networks particularly blood transportation vasculature.

  12. Terahertz pulse driven Josephson junctions

    Energy Technology Data Exchange (ETDEWEB)

    Camerlingo, Carlo, E-mail: c.camerlingo@cib.na.cnr.it [CNR - Consiglio Nazionale delle Ricerche, Istituto di Cibernetica ' E. Caianiello' , Via Campi Flegrei 34, I-80078 Pozzuoli (Italy)

    2011-09-15

    Theoretical model of the ac Josephson effect in pulsed current driven junctions. Evaluation of the voltage response of a THz pulsed radiation driven Josephson junction. The pulsed current bias induces steps in the junction I/V characteristics for voltages depending on the pulse rate. Working principles of a fast response detector for THz pulsed radiation. The voltage response of a Josephson junction to a pulsed terahertz current is evaluated in the limit of a negligible junction capacitance (overdamped limit). The time-dependent superconductor phase difference across the junction is calculated in the framework of the standard resistive shunted junction model by using a perturbative method. The pulsed current bias affects the time average value of the voltage across the junction and current steps are induced in the current-voltage characteristics for voltage values depending on the pulse repetition rate. The current step height is proportional to the square of the pulse time width ({tau}) to the period (T) ratio. A fast response detector for pulsed Terahertz radiation is proposed, with an expected responsivity of the order of 0.1 V/W and an equivalent noise power of about 3 x 10{sup -10} W/Hz{sup 1/2}.

  13. Electron transport in molecular junctions

    DEFF Research Database (Denmark)

    Jin, Chengjun

    This thesis addresses the electron transport in molecular junctions, focusing on the energy level alignment and correlation effects. Various levels of theory have been applied to study the structural and electronic effects in different molecular junctions, starting from the single particle density...

  14. Topological Properties of Superconducting Junctions

    NARCIS (Netherlands)

    Pikulin, D.I.; Nazarov, Y.V.

    Motivated by recent developments in the field of one-dimensional topological superconductors, we investigate the topological properties of s-matrix of generic superconducting junctions where dimension should not play any role. We argue that for a finite junction the s-matrix is always topologically

  15. Microstructure of Josephson junctions: Effect on supercurrent transport in YBCO grain boundary and barrier layer junctions

    International Nuclear Information System (INIS)

    Merkle, K.L.; Huang, Y.

    1998-01-01

    The electric transport of high-temperature superconductors, such as YBa 2 Cu 3 O 7-x (YBCO), can be strongly restricted by the presence of high-angle grain boundaries (GB). This weak-link behavior is governed by the macroscopic GB geometry and the microscopic grain boundary structure and composition at the atomic level. Whereas grain boundaries present a considerable impediment to high current applications of high T c materials, there is considerable commercial interest in exploiting the weak-link-nature of grain boundaries for the design of microelectronic devices, such as superconducting quantum interference devices (SQUIDs). The Josephson junctions which form the basis of this technology can also be formed by introducing artificial barriers into the superconductor. The authors have examined both types of Josephson junctions by EM techniques in an effort to understand the connection between microstructure/chemistry and electrical transport properties. This knowledge is a valuable resource for the design and production of improved devices

  16. Quantitatively accurate calculations of conductance and thermopower of molecular junctions

    DEFF Research Database (Denmark)

    Markussen, Troels; Jin, Chengjun; Thygesen, Kristian Sommer

    2013-01-01

    ) connected to gold electrodes using first‐principles calculations. We find excellent agreement with experiments for both molecules when exchange–correlation effects are described by the many‐body GW approximation. In contrast, results from standard density functional theory (DFT) deviate from experiments......‐interaction errors and image charge effects. Finally, we show that the conductance and thermopower of the considered junctions are relatively insensitive to the metal–molecule bonding geometry. Our results demonstrate that electronic and thermoelectric properties of molecular junctions can be predicted from first‐principles...... calculations when exchange–correlation effects are taken properly into account....

  17. Highly doped layer for tunnel junctions in solar cells

    Science.gov (United States)

    Fetzer, Christopher M.

    2017-08-01

    A highly doped layer for interconnecting tunnel junctions in multijunction solar cells is presented. The highly doped layer is a delta doped layer in one or both layers of a tunnel diode junction used to connect two or more p-on-n or n-on-p solar cells in a multijunction solar cell. A delta doped layer is made by interrupting the epitaxial growth of one of the layers of the tunnel diode, depositing a delta dopant at a concentration substantially greater than the concentration used in growing the layer of the tunnel diode, and then continuing to epitaxially grow the remaining tunnel diode.

  18. Ion bipolar junction transistors.

    Science.gov (United States)

    Tybrandt, Klas; Larsson, Karin C; Richter-Dahlfors, Agneta; Berggren, Magnus

    2010-06-01

    Dynamic control of chemical microenvironments is essential for continued development in numerous fields of life sciences. Such control could be achieved with active chemical circuits for delivery of ions and biomolecules. As the basis for such circuitry, we report a solid-state ion bipolar junction transistor (IBJT) based on conducting polymers and thin films of anion- and cation-selective membranes. The IBJT is the ionic analogue to the conventional semiconductor BJT and is manufactured using standard microfabrication techniques. Transistor characteristics along with a model describing the principle of operation, in which an anionic base current amplifies a cationic collector current, are presented. By employing the IBJT as a bioelectronic circuit element for delivery of the neurotransmitter acetylcholine, its efficacy in modulating neuronal cell signaling is demonstrated.

  19. Gap junction modulation by extracellular signaling molecules: the thymus model

    Directory of Open Access Journals (Sweden)

    Alves L.A.

    2000-01-01

    Full Text Available Gap junctions are intercellular channels which connect adjacent cells and allow direct exchange of molecules of low molecular weight between them. Such a communication has been described as fundamental in many systems due to its importance in coordination, proliferation and differentiation. Recently, it has been shown that gap junctional intercellular communication (GJIC can be modulated by several extracellular soluble factors such as classical hormones, neurotransmitters, interleukins, growth factors and some paracrine substances. Herein, we discuss some aspects of the general modulation of GJIC by extracellular messenger molecules and more particularly the regulation of such communication in the thymus gland. Additionally, we discuss recent data concerning the study of different neuropeptides and hormones in the modulation of GJIC in thymic epithelial cells. We also suggest that the thymus may be viewed as a model to study the modulation of gap junction communication by different extracellular messengers involved in non-classical circuits, since this organ is under bidirectional neuroimmunoendocrine control.

  20. dc properties of series-parallel arrays of Josephson junctions in an external magnetic field

    International Nuclear Information System (INIS)

    Lewandowski, S.J.

    1991-01-01

    A detailed dc theory of superconducting multijunction interferometers has previously been developed by several authors for the case of parallel junction arrays. The theory is now extended to cover the case of a loop containing several junctions connected in series. The problem is closely associated with high-T c superconductors and their clusters of intrinsic Josephson junctions. These materials exhibit spontaneous interferometric effects, and there is no reason to assume that the intrinsic junctions form only parallel arrays. A simple formalism of phase states is developed in order to express the superconducting phase differences across the junctions forming a series array as functions of the phase difference across the weakest junction of the system, and to relate the differences in critical currents of the junctions to gaps in the allowed ranges of their phase functions. This formalism is used to investigate the energy states of the array, which in the case of different junctions are split and separated by energy barriers of height depending on the phase gaps. Modifications of the washboard model of a single junction are shown. Next a superconducting inductive loop containing a series array of two junctions is considered, and this model is used to demonstrate the transitions between phase states and the associated instabilities. Finally, the critical current of a parallel connection of two series arrays is analyzed and shown to be a multivalued function of the externally applied magnetic flux. The instabilities caused by the presence of intrinsic serial junctions in granular high-T c materials are pointed out as a potential source of additional noise

  1. Electrical transport through a metal-molecule-metal junction

    International Nuclear Information System (INIS)

    Kergueris, Ch.

    1998-01-01

    We investigate the electrical transport through a very few molecules connected to metallic electrodes at room temperature. First, the state of the art in molecular electronics is outlined. We present the most convincing molecular devices reported so far in the literature and the theoretical tools available to analyze the electron transport mechanism through a molecular junction. Second, we describe the use of mechanically controllable break junctions to investigate the electron transport properties through a metal-molecule-metal junction. Two kinds of molecules were adsorbed on the two facing gold electrodes, dodecane-thiol (DT) and bis-thiol-ter-thiophene (α,ω T3), that are basically expected to behave as an insulator and as a molecular wire, respectively. In the latter case, we study the chemical reactivity of the molecule and show that α,ω T3 is chemically adsorbed on gold electrodes. Current-voltage characteristics of the junction were observed at room temperature. The Gold-DT-Gold junction behaves as a simple metal-insulator-metal junction. On the other hand, the electron transport through a Gold-α,ω T3-Gold junction explicitly involves the electronic structure of the molecule which gives rise to step-like features in the current-voltage characteristics. The measured zero bias conductance is interpreted using the scattering theory. At high bias, we discuss two different models: a coherent model where the electron has no time to be completely re-localized in the molecule and a sequential model where the electron is localized in the molecule during the transfer. Finally, we show that the mechanical action of decreasing the inter-electrodes spacing can be used to induce a strong modification of the current-voltage characteristics. (author)

  2. Imaging of cervicothoracic junction trauma

    Directory of Open Access Journals (Sweden)

    Wongwaisayawan S

    2013-01-01

    Full Text Available Sirote Wongwaisayawan,1 Ruedeekorn Suwannanon,2 Rathachai Kaewlai11Department of Radiology, Ramathibodi Hospital and Mahidol University, Bangkok, Thailand; 2Department of Radiology, Faculty of Medicine, Prince of Songkla University, Hat Yai, ThailandAbstract: Cervicothoracic junction trauma is an important cause of morbidity and mortality in trauma patients. Imaging has played an important role in identifying injuries and guiding appropriate, timely therapy. Computed tomography is currently a method of choice for diagnosing cervicothoracic junction trauma, in which the pattern of injuries often suggests possible mechanisms and potential injuries. In this article, the authors describe and illustrate common and uncommon injuries that can occur in the cervicothoracic junction.Keywords: cervicothoracic junction, cervical spine, trauma, imaging, radiology

  3. The Control of Junction Flows

    National Research Council Canada - National Science Library

    Smith, Charles

    1997-01-01

    An experimental study of the effects of spatially-limited (i.e. localized) surface suction on unsteady laminar and turbulent junction flows was performed using hydrogen bubble flow visualization and Particle Image Velocimetry (PIV...

  4. ADAM10 Is Involved in Cell Junction Assembly in Early Porcine Embryo Development.

    Directory of Open Access Journals (Sweden)

    Jeongwoo Kwon

    Full Text Available ADAM10 (A Disintegrin and Metalloprotease domain-containing protein 10 is a cell surface protein with a unique structure possessing both potential adhesion and protease domains. However, the role of ADAM10 in preimplantation stage embryos is not clear. In this study, we examined the expression patterns and functional roles of ADAM10 in porcine parthenotes during preimplantation development. The transcription level of ADAM10 dramatically increased from the morula stage onward. Immunostaining revealed that ADAM10 was present in both the nucleus and cytoplasm in early cleavage stage embryos, and localized to the apical region of the outer cells in morula and blastocyst embryos. Knockdown (KD of ADAM10 using double strand RNA did not alter preimplantation embryo development until morula stage, but resulted in significantly reduced development to blastocyst stage. Moreover, the KD blastocyst showed a decrease in gene expression of adherens and tight junction (AJ/TJ, and an increase in trophectoderm TJ permeability by disrupting TJ assembly. Treatment with an ADAM10 specific chemical inhibitor, GI254023X, at the morula stage also inhibited blastocyst development and led to disruption of TJ assembly. An in situ proximity ligation assay demonstrated direct interaction of ADAM10 with coxsackie virus and adenovirus receptor (CXADR, supporting the involvement of ADAM10 in TJ assembly. In conclusion, our findings strongly suggest that ADADM10 is important for blastocyst formation rather than compaction, particularly for TJ assembly and stabilization in preimplantation porcine parthenogenetic development.

  5. Intercellular junctions in nerve-free hydra

    DEFF Research Database (Denmark)

    McDowall, A W; Grimmelikhuijzen, C J

    1980-01-01

    Epithelial cells of nerve-free hydra contain septate and gap junctions. In thin sections the gap junctions are characterized by a gap of 3-4 nm. Freeze-fracture demonstrates the presence of septate junctions and two further types of structures: (i) the "E-type" or "inverted" gap junctions...

  6. Josephson junctions with ferromagnetic interlayer

    Energy Technology Data Exchange (ETDEWEB)

    Wild, Georg Hermann

    2012-03-04

    We report on the fabrication of superconductor/insulator/ferromagnetic metal/superconductor (Nb/AlO{sub x}/Pd{sub 0.82}Ni{sub 0.18}/Nb) Josephson junctions (SIFS JJs) with high critical current densities, large normal resistance times area products, and high quality factors. For these junctions, a transition from 0- to {pi}-coupling is observed for a thickness d{sub F}=6 nm of the ferromagnetic Pd{sub 0.82}Ni{sub 0.18} interlayer. The magnetic field dependence of the critical current of the junctions demonstrates good spatial homogeneity of the tunneling barrier and ferromagnetic interlayer. Magnetic characterization shows that the Pd{sub 0.82}Ni{sub 0.18} has an out-of-plane anisotropy and large saturation magnetization indicating negligible dead layers at the interfaces. A careful analysis of Fiske modes up to about 400 GHz provides valuable information on the junction quality factor and the relevant damping mechanisms. Whereas losses due to quasiparticle tunneling dominate at low frequencies, at high frequencies the damping is explained by the finite surface resistance of the junction electrodes. High quality factors of up to 30 around 200 GHz have been achieved. They allow to study the junction dynamics, in particular the switching probability from the zero-voltage into the voltage state with and without microwave irradiation. The experiments with microwave irradiation are well explained within semi-classical models and numerical simulations. In contrast, at mK temperature the switching dynamics without applied microwaves clearly shows secondary quantum effects. Here, we could observe for the first time macroscopic quantum tunneling in Josephson junctions with a ferromagnetic interlayer. This observation excludes fluctuations of the critical current as a consequence of an unstable magnetic domain structure of the ferromagnetic interlayer and affirms the suitability of SIFS Josephson junctions for quantum information processing.

  7. Peltier cooling in molecular junctions

    Science.gov (United States)

    Cui, Longji; Miao, Ruijiao; Wang, Kun; Thompson, Dakotah; Zotti, Linda Angela; Cuevas, Juan Carlos; Meyhofer, Edgar; Reddy, Pramod

    2018-02-01

    The study of thermoelectricity in molecular junctions is of fundamental interest for the development of various technologies including cooling (refrigeration) and heat-to-electricity conversion1-4. Recent experimental progress in probing the thermopower (Seebeck effect) of molecular junctions5-9 has enabled studies of the relationship between thermoelectricity and molecular structure10,11. However, observations of Peltier cooling in molecular junctions—a critical step for establishing molecular-based refrigeration—have remained inaccessible. Here, we report direct experimental observations of Peltier cooling in molecular junctions. By integrating conducting-probe atomic force microscopy12,13 with custom-fabricated picowatt-resolution calorimetric microdevices, we created an experimental platform that enables the unified characterization of electrical, thermoelectric and energy dissipation characteristics of molecular junctions. Using this platform, we studied gold junctions with prototypical molecules (Au-biphenyl-4,4'-dithiol-Au, Au-terphenyl-4,4''-dithiol-Au and Au-4,4'-bipyridine-Au) and revealed the relationship between heating or cooling and charge transmission characteristics. Our experimental conclusions are supported by self-energy-corrected density functional theory calculations. We expect these advances to stimulate studies of both thermal and thermoelectric transport in molecular junctions where the possibility of extraordinarily efficient energy conversion has been theoretically predicted2-4,14.

  8. Electronic thermometry in tunable tunnel junction

    Energy Technology Data Exchange (ETDEWEB)

    Maksymovych, Petro

    2016-03-15

    A tunable tunnel junction thermometry circuit includes a variable width tunnel junction between a test object and a probe. The junction width is varied and a change in thermovoltage across the junction with respect to the change in distance across the junction is determined. Also, a change in biased current with respect to a change in distance across the junction is determined. A temperature gradient across the junction is determined based on a mathematical relationship between the temperature gradient, the change in thermovoltage with respect to distance and the change in biased current with respect to distance. Thermovoltage may be measured by nullifying a thermoelectric tunneling current with an applied voltage supply level. A piezoelectric actuator may modulate the probe, and thus the junction width, to vary thermovoltage and biased current across the junction. Lock-in amplifiers measure the derivatives of the thermovoltage and biased current modulated by varying junction width.

  9. Long Josephson tunnel junctions with doubly connected electrodes

    DEFF Research Database (Denmark)

    Monaco, R.; Mygind, J.; Koshelets, V. P.

    2012-01-01

    In order to mimic the phase changes in the primordial Big Bang, several cosmological solid-state experiments have been conceived, during the last decade, to investigate the spontaneous symmetry breaking in superconductors and superfluids cooled through their transition temperature. In one...

  10. Charge Transport Processes in Molecular Junctions

    Science.gov (United States)

    Smith, Christopher Eugene

    Molecular electronics (ME) has evolved into a rich area of exploration that combines the fields of chemistry, materials, electronic engineering and computational modeling to explore the physics behind electronic conduction at the molecular level. Through studying charge transport properties of single molecules and nanoscale molecular materials the field has gained the potential to bring about new avenues for the miniaturization of electrical components where quantum phenomena are utilized to achieve solid state molecular device functionality. Molecular junctions are platforms that enable these studies and consist of a single molecule or a small group of molecules directly connected to electrodes. The work presented in this thesis has built upon the current understanding of the mechanisms of charge transport in ordered junctions using self-assembled monolayer (SAM) molecular thin films. Donor and acceptor compounds were synthesized and incorporated into SAMs grown on metal substrates then the transport properties were measured with conducting probe atomic force microscopy (CP-AFM). In addition to experimentally measured current-voltage (I-V) curves, the transport properties were addressed computationally and modeled theoretically. The key objectives of this project were to 1) investigate the impact of molecular structure on hole and electron charge transport, 2) understand the nature of the charge carriers and their structure-transport properties through long (films, and open opportunities to engineer improved electronic functionality into molecular devices.

  11. Connected Traveler

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, Alex

    2015-11-01

    The Connected Traveler project is a multi-disciplinary undertaking that seeks to validate potential for transformative transportation system energy savings by incentivizing efficient traveler behavior. This poster outlines various aspects of the Connected Traveler project, including market opportunity, understanding traveler behavior and decision-making, automation and connectivity, and a projected timeline for Connected Traveler's key milestones.

  12. Development and Implementation of a Segment/Junction Box Level Database for the ITS Fiber Optic Conduit Network

    Science.gov (United States)

    2012-03-01

    This project initiated the development of a computerized database of ITS facilities, including conduits, junction : boxes, cameras, connections, etc. The current system consists of a database of conduit sections of various lengths. : Over the length ...

  13. Monitoring drilling mud composition using flowing liquid junction electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Jasinski, R.; Fletcher, P.; Vercaemer, C.

    1990-06-27

    The concentration of a chosen ionic component of a drilling mud is determined from the potential difference between an ion selective electrode, selective to the component and a reference electrode, the reference electrode being connected to the mud by a liquid junction through which reference electrolyte flows from the electrode to the mud. The system avoids errors due to undesirable interactions between the mud and the reference electrode materials. (author).

  14. Field-effect P-N junction

    Science.gov (United States)

    Regan, William; Zettl, Alexander

    2015-05-05

    This disclosure provides systems, methods, and apparatus related to field-effect p-n junctions. In one aspect, a device includes an ohmic contact, a semiconductor layer disposed on the ohmic contact, at least one rectifying contact disposed on the semiconductor layer, a gate including a layer disposed on the at least one rectifying contact and the semiconductor layer and a gate contact disposed on the layer. A lateral width of the rectifying contact is less than a semiconductor depletion width of the semiconductor layer. The gate contact is electrically connected to the ohmic contact to create a self-gating feedback loop that is configured to maintain a gate electric field of the gate.

  15. A physics-explicit model of bacterial conjugation shows the stabilizing role of the conjugative junction

    OpenAIRE

    Pastuszak, Jakub; Waclaw, Bartlomiej

    2017-01-01

    Conjugation is a process in which bacteria exchange DNA through a physical connection (conjugative junction) between mating cells. Despite its significance for processes such as the spread of antibiotic resistance, the role of physical forces in conjugation is poorly understood. Here we use computer models to show that the conjugative junction not only serves as a link to transfer the DNA but it also mechanically stabilises the mating pair which significantly increases the conjugation rate. W...

  16. Radiation detection with Nb/Al-AlOx/Al/Nb superconducting tunnel junctions

    International Nuclear Information System (INIS)

    Matsumura, Atsuki; Takahashi, Toru; Kurakado, Masahiko

    1992-01-01

    Superconductor radiation detectors have the possibility of 20-30 times better energy resolution than that of a high resolution Si detector. We fabricated Nb/Al-AlOx/Al/Nb superconducting tunnel junctions with low leakage current. X rays were detected with large area junctions of 178x178 μm 2 . High energy resolution of 160 eV for 5.9 keV was obtained. We also fabricated series connected junctions which covers a rather large area of 4x4 mm 2 . α particles injected into the rear substrate were detected using nonthermal phonons induced by the radiations in the substrate. (author)

  17. IJS: An Intelligent Junction Selection Based Routing Protocol for VANET to Support ITS Services.

    Science.gov (United States)

    Bhoi, Sourav Kumar; Khilar, Pabitra Mohan

    2014-01-01

    Selecting junctions intelligently for data transmission provides better intelligent transportation system (ITS) services. The main problem in vehicular communication is high disturbances of link connectivity due to mobility and less density of vehicles. If link conditions are predicted earlier, then there is a less chance of performance degradation. In this paper, an intelligent junction selection based routing protocol (IJS) is proposed to transmit the data in a quickest path, in which the vehicles are mostly connected and have less link connectivity problem. In this protocol, a helping vehicle is set at every junction to control the communication by predicting link failures or network gaps in a route. Helping vehicle at the junction produces a score for every neighboring junction to forward the data to the destination by considering the current traffic information and selects that junction which has minimum score. IJS protocol is implemented and compared with GyTAR, A-STAR, and GSR routing protocols. Simulation results show that IJS performs better in terms of average end-to-end delay, network gap encounter, and number of hops.

  18. Gravitation at the Josephson Junction

    Directory of Open Access Journals (Sweden)

    Victor Atanasov

    2018-01-01

    Full Text Available A geometric potential from the kinetic term of a constrained to a curved hyperplane of space-time quantum superconducting condensate is derived. An energy conservation relation involving the geometric field at every material point in the superconductor is demonstrated. At a Josephson junction the energy conservation relation implies the possibility of transforming electric energy into geometric field energy, that is, curvature of space-time. Experimental procedures to verify that the Josephson junction can act as a voltage-to-curvature converter are discussed.

  19. Finite element analysis of inclined nozzle-plate junctions

    International Nuclear Information System (INIS)

    Dixit, K.B.; Seth, V.K.; Krishnan, A.; Ramamurthy, T.S.; Dattaguru, B.; Rao, A.K.

    1979-01-01

    Estimation of stress concentration at nozzle to plate or shell junctions is a significant problem in the stress analysis of nuclear reactors. The topic is a subject matter of extensive investigations and earlier considerable success has been reported on analysis for the cases when the nozzle is perpendicular to the plate or is radial to the shell. Analytical methods for the estimation of stress concentrations for the practical situations when the intersecting nozzle is inclined to the plate or is non-radial to the shell is rather scanty. Specific complications arise in dealing with the junction region when the nozzle with circular cross-section meets the non-circular cut-out on the plate or shell. In this paper a finite element analysis is developed for inclined nozzles and results are presented for nozzle-plate junctions. A method of analysis is developed with a view to achieving simultaneously accuracy of results and simplicity in the choice of elements and their connectivity. The circular nozzle is treated by axisymmetric conical shell elements. The nozzle portion in the region around the junction and the flat plate is dealt with by triangular flat shell elements. Special transition elements are developed for joining the flat shell elements with the axisymmetric elements under non-axisymmetric loading. A substructure method of analysis is adopted which achieves considerable economy in handling the structure and also conveniently combines the different types of elements in the structure. (orig.)

  20. Perfect spin filtering by symmetry in molecular junctions

    Science.gov (United States)

    Li, Dongzhe; Dappe, Yannick J.; Smogunov, Alexander

    2016-05-01

    Obtaining highly spin-polarized currents in molecular junctions is crucial and important for nanoscale spintronics devices. Motivated by our recent symmetry-based theoretical argument for complete blocking of one spin conductance channel in model molecular junctions [A. Smogunov and Y. J. Dappe, Nano Lett. 15, 3552 (2015), 10.1021/acs.nanolett.5b01004], we explore the generality of the proposed mechanism and the degree of achieved spin-polarized current for realistic molecular junctions made of various ferromagnetic electrodes (Ni, Co, Fe) connected by different molecules (quaterthiophene or p -quaterphenyl). A simple analysis of the spin-resolved local density of states of a free electrode allowed us to identify the Fe(110) as the most optimal electrode, providing perfect spin filtering and high conductance at the same time. These results are confirmed by ab initio quantum transport calculations and are similar to those reported previously for model junctions. It is found, moreover, that the distortion of the p -quaterphenyl molecule plays an important role, reducing significantly the overall conductance.

  1. Gap junctions and motor behavior

    DEFF Research Database (Denmark)

    Kiehn, Ole; Tresch, Matthew C.

    2002-01-01

    The production of any motor behavior requires coordinated activity in motor neurons and premotor networks. In vertebrates, this coordination is often assumed to take place through chemical synapses. Here we review recent data suggesting that electrical gap-junction coupling plays an important role...... to the production of motor behavior in adult mammals....

  2. Gap Junctions and Chagas Disease

    Science.gov (United States)

    Adesse, Daniel; Goldenberg, Regina Coeli; Fortes, Fabio S.; Jasmin; Iacobas, Dumitru A.; Iacobas, Sanda; de Carvalho, Antonio Carlos Campos; de Narareth Meirelles, Maria; Huang, Huan; Soares, Milena B.; Tanowitz, Herbert B.; Garzoni, Luciana Ribeiro; Spray, David C.

    2013-01-01

    Gap junction channels provide intercellular communication between cells. In the heart, these channels coordinate impulse propagation along the conduction system and through the contractile musculature, thereby providing synchronous and optimal cardiac output. As in other arrhythmogenic cardiac diseases, chagasic cardiomyopathy is associated with decreased expression of the gap junction protein connexin43 (Cx43) and its gene. Our studies of cardiac myocytes infected with Trypanosoma cruzi have revealed that synchronous contraction is greatly impaired and gap junction immunoreactivity is lost in infected cells. Such changes are not seen for molecules forming tight junctions, another component of the intercalated disc in cardiac myocytes. Transcriptomic studies of hearts from mouse models of Chagas disease and from acutely infected cardiac myocytes in vitro indicate profound remodelling of gene expression patterns involving heart rhythm determinant genes, suggesting underlying mechanisms of the functional pathology. One curious feature of the altered expression of Cx43 and its gene expression is that it is limited in both extent and location, suggesting that the more global deterioration in cardiac function may result in part from spread of damage signals from more seriously compromised cells to healthier ones. PMID:21884887

  3. Tectonic pattern of the Azores spreading centre and triple junction

    Science.gov (United States)

    Searle, Roger

    1980-12-01

    The major tectonic elements of the Azores triple junction have been mapped using long-range side-scan sonar. The data enable the Mid-Atlantic Ridge axis to be located with a precision of a few kilometres. Major faults and other tectonic and volcanic elements of the ridge maintain their regional trend of 010° to 020° past the triple junction area. There is no oblique spreading, and only minor transform offsets of the Mid-Atlantic Ridge occur here. The main effect of the triple junction or Azores hot spot is to diminish the amplitude of the median valley to 200 m or less. There is no axial high: a topographic high seen on several profiles is located to the east of the Mid-Atlantic Ridge spreading axis and does not appear to have any fundamental significance. The third arm of the triple junction includes the Azores srreading centre which appears to have developed as a series of en echelon rifted basins (the Terceira Rift) extending from Formigas Trough at 36.8°N, 24.5°W to a point near 39.3°N, 28.8°W. There are indications that recent activity in the spreading centre may be concentrated in a series of ridges which flank the older rifted basins. Until recently the northwest end of the Terceira Rift was connected to the Mid-Atlantic Ridge axis either directly at an RRR junction, or via a transform fault. The triple junction has probably moved south during the last 6 Ma to a positin on the Mid-Atlantic Ridge near 38.7°N. Initiation of the Azores spreading centre may have occurred during the 36 Ma B.P. rearrangement of poles, with an RFF triple junction north from the East Azores fracture zone to the North Azores fracture zone and transferring a wedge of European plate to the African plate. The tectonic elements revealed by this study are in good agreement with inferred earthquake mechanisms and with the RM2 plate tectonic model of Minster and Jordan, but east-west motion between North America and Africa does not seem to be compatible with the other motions at the

  4. Dynamics of pi-junction interferometer circuits

    DEFF Research Database (Denmark)

    Kornkev, V.K.; Mozhaev, P.B.; Borisenko, I.V.

    2002-01-01

    The pi-junction superconducting circuit dynamics was studied by means of numerical simulation technique. Parallel arrays consisting of Josephson junctions of both 0- and pi-type were studied as a model of high-T-c grain-boundary Josephson junction. The array dynamics and the critical current...... dependence on magnetic field are discussed. Experimental results for dc interferometers with 0 and pi high-T-c bi-crystal Josephson junctions are reported and discussed in comparison with numerical simulation....

  5. Modelling and Analysis of Long Josephson Junctions

    NARCIS (Netherlands)

    Visser, T.P.P.

    2002-01-01

    For various reasons people have been interested in Josephson junctions. Ranging from "understanding nature" to building quantum computers. In this thesis we focus on a special type of junction (the long junction) and to a special type of problem fluxon dynamics.

  6. Soliton bunching in annular Josephson junctions

    DEFF Research Database (Denmark)

    Vernik, I.V; Lazarides, Nickos; Sørensen, Mads Peter

    1996-01-01

    By studying soliton (fluxon) motion in long annular Josephson junctions it is possible to avoid the influence of the boundaries and soliton-soliton collisions present in linear junctions. A new experimental design consisting of a niobium coil placed on top of an annular junction has been used...

  7. Quantum phase-slip junction under microwave irradiation

    Science.gov (United States)

    Di Marco, A.; Hekking, F. W. J.; Rastelli, G.

    2015-05-01

    We consider the dynamics of a quantum phase-slip junction (QPSJ), a dual Josephson junction, connected to a microwave source with frequency ωmw. With respect to an ordinary Josephson junction, a QPSJ can sustain dual Shapiro steps, consisting of well-defined current plateaus at multiple integers of e ωmw/π in the current-voltage (I -V ) characteristic. The experimental observation of these plateaus has been elusive up to now. We argue that thermal as well as quantum fluctuations can smear the I -V characteristic considerably. In order to understand these effects, we study a current-biased QPSJ under microwave irradiation and connected to an inductive and resistive environment. We find that the effect of the fluctuations is governed by the resistance of the environment and by the ratio of the phase-slip energy and the inductive energy. Our results are of interest for experiments aiming at the observation of dual Shapiro steps in QPSJ devices for the definition of a new quantum current standard.

  8. Flexible 2D layered material junctions

    Science.gov (United States)

    Balabai, R.; Solomenko, A.

    2018-03-01

    Within the framework of the methods of the electron density functional and the ab initio pseudopotential, we have obtained the valence electron density spatial distribution, the densities of electron states, the widths of band gaps, the charges on combined regions, and the Coulomb potentials for graphene-based flexible 2D layered junctions, using author program complex. It is determined that the bending of the 2D layered junctions on the angle α leads to changes in the electronic properties of these junctions. In the graphene/graphane junction, there is clear charge redistribution with different signs in the regions of junctions. The presence in the heterojunctions of charge regions with different signs leads to the formation of potential barriers. The greatest potential jump is in the graphene/fluorographene junction. The greatest value of the band gap width is in the graphene/graphane junction.

  9. Josephson junctions and dark energy

    Science.gov (United States)

    Jetzer, Philippe; Straumann, Norbert

    2006-08-01

    In a recent paper Beck and Mackey [C. Beck, M.C. Mackey, astro-ph/0603397] argue that the argument we gave in our paper [Ph. Jetzer, N. Straumann, Phys. Lett. B 606 (2005) 77, astro-ph/0411034] to disprove their claim that dark energy can be discovered in the Lab through noise measurements of Josephson junctions is incorrect. In particular, they emphasize that the measured noise spectrum in Josephson junctions is a consequence of the fluctuation dissipation theorem, while our argument was based on equilibrium statistical mechanics. In this note we show that the fluctuation dissipation relation does not depend upon any shift of vacuum (zero-point) energies, and therefore, as already concluded in our previous paper, dark energy has nothing to do with the proposed measurements.

  10. Josephson junctions and dark energy

    International Nuclear Information System (INIS)

    Jetzer, Philippe; Straumann, Norbert

    2006-01-01

    In a recent paper Beck and Mackey [C. Beck, M.C. Mackey, astro-ph/0603397] argue that the argument we gave in our paper [Ph. Jetzer, N. Straumann, Phys. Lett. B 606 (2005) 77, astro-ph/0411034] to disprove their claim that dark energy can be discovered in the Lab through noise measurements of Josephson junctions is incorrect. In particular, they emphasize that the measured noise spectrum in Josephson junctions is a consequence of the fluctuation dissipation theorem, while our argument was based on equilibrium statistical mechanics. In this note we show that the fluctuation dissipation relation does not depend upon any shift of vacuum (zero-point) energies, and therefore, as already concluded in our previous paper, dark energy has nothing to do with the proposed measurements

  11. Josephson junctions and dark energy

    Energy Technology Data Exchange (ETDEWEB)

    Jetzer, Philippe [Institute for Theoretical Physics, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich (Switzerland)]. E-mail: jetzer@physik.unizh.ch; Straumann, Norbert [Institute for Theoretical Physics, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich (Switzerland)

    2006-08-03

    In a recent paper Beck and Mackey [C. Beck, M.C. Mackey, astro-ph/0603397] argue that the argument we gave in our paper [Ph. Jetzer, N. Straumann, Phys. Lett. B 606 (2005) 77, astro-ph/0411034] to disprove their claim that dark energy can be discovered in the Lab through noise measurements of Josephson junctions is incorrect. In particular, they emphasize that the measured noise spectrum in Josephson junctions is a consequence of the fluctuation dissipation theorem, while our argument was based on equilibrium statistical mechanics. In this note we show that the fluctuation dissipation relation does not depend upon any shift of vacuum (zero-point) energies, and therefore, as already concluded in our previous paper, dark energy hathing to do with the proposed measurements.

  12. Extended Majorana zero modes in a topological superconducting-normal T-junction

    Science.gov (United States)

    Spånslätt, Christian; Ardonne, Eddy

    2017-03-01

    We investigate the sub gap properties of a three terminal Josephson T-junction composed of topologically superconducting wires connected by a normal metal region. This system naturally hosts zero energy Andreev bound states which are of self-conjugate Majorana nature and we show that they are, in contrast to ordinary Majorana zero modes, spatially extended in the normal metal region. If the T-junction respects time-reversal symmetry, we show that a zero mode is distributed only in two out of three arms in the junction and tuning the superconducting phases allows for transfer of the mode between the junction arms. We further provide tunneling conductance calculations showing that these features can be detected in experiments. Our findings suggest an experimental platform for studying the nature of spatially extended Majorana zero modes.

  13. An Evaluation of Test and Physical Uncertainty of Measuring Vibration in Wooden Junctions

    DEFF Research Database (Denmark)

    Dickow, Kristoffer Ahrens; Kirkegaard, Poul Henning; Andersen, Lars Vabbersgaard

    2012-01-01

    In the present paper a study of test and material uncertainty in modal analysis of certain wooden junctions is presented. The main structure considered here is a T-junction made from a particleboard plate connected to a spruce beam of rectangular cross section. The size of the plate is 1.2 m by 0.......6 m. The T-junctions represent cut-outs of actual full size floor assemblies. The aim of the experiments is to investigate the underlying uncertainties of both the test method as well as variation in material and craftmanship. For this purpose, ten nominally identical junctions are tested and compared...... to each other in terms of modal parameters such as natural frequencies, modeshapes and damping. Considerations regarding the measurement procedure and test setup are discussed. The results indicate a large variation of the response at modes where the coupling of torsion in the beam to bending of the plate...

  14. Innexin gap junctions in nerve cells coordinate spontaneous contractile behavior in Hydra polyps.

    Science.gov (United States)

    Takaku, Yasuharu; Hwang, Jung Shan; Wolf, Alexander; Böttger, Angelika; Shimizu, Hiroshi; David, Charles N; Gojobori, Takashi

    2014-01-07

    Nerve cells and spontaneous coordinated behavior first appeared near the base of animal evolution in the common ancestor of cnidarians and bilaterians. Experiments on the cnidarian Hydra have demonstrated that nerve cells are essential for this behavior, although nerve cells in Hydra are organized in a diffuse network and do not form ganglia. Here we show that the gap junction protein innexin-2 is expressed in a small group of nerve cells in the lower body column of Hydra and that an anti-innexin-2 antibody binds to gap junctions in the same region. Treatment of live animals with innexin-2 antibody eliminates gap junction staining and reduces spontaneous body column contractions. We conclude that a small subset of nerve cells, connected by gap junctions and capable of synchronous firing, act as a pacemaker to coordinate the contraction of the body column in the absence of ganglia.

  15. Innexin gap junctions in nerve cells coordinate spontaneous contractile behavior in Hydra polyps

    KAUST Repository

    Takaku, Yasuharu

    2014-01-07

    Nerve cells and spontaneous coordinated behavior first appeared near the base of animal evolution in the common ancestor of cnidarians and bilaterians. Experiments on the cnidarian Hydra have demonstrated that nerve cells are essential for this behavior, although nerve cells in Hydra are organized in a diffuse network and do not form ganglia. Here we show that the gap junction protein innexin-2 is expressed in a small group of nerve cells in the lower body column of Hydra and that an anti-innexin-2 antibody binds to gap junctions in the same region. Treatment of live animals with innexin-2 antibody eliminates gap junction staining and reduces spontaneous body column contractions. We conclude that a small subset of nerve cells, connected by gap junctions and capable of synchronous firing, act as a pacemaker to coordinate the contraction of the body column in the absence of ganglia.

  16. Ephrin-Bs Drive Junctional Downregulation and Actin Stress Fiber Disassembly to Enable Wound Re-epithelialization

    Directory of Open Access Journals (Sweden)

    Robert Nunan

    2015-11-01

    Full Text Available For a skin wound to successfully heal, the cut epidermal-edge cells have to migrate forward at the interface between scab and healthy granulation tissue. Much is known about how lead-edge cells migrate, but very little is known about the mechanisms that enable active participation by cells further back. Here we show that ephrin-B1 and its receptor EphB2 are both upregulated in vivo, just for the duration of repair, in the first 70 or so rows of epidermal cells, and this signal leads to downregulation of the molecular components of adherens and tight (but not desmosomal junctions, leading to loosening between neighbors and enabling shuffle room among epidermal cells. Additionally, this signaling leads to the shutdown of actomyosin stress fibers in these same epidermal cells, which may act to release tension within the wound monolayer. If this signaling axis is perturbed, then disrupted healing is a consequence in mouse and man.

  17. Superconducting tunnel-junction refrigerator

    International Nuclear Information System (INIS)

    Melton, R.G.; Paterson, J.L.; Kaplan, S.B.

    1980-01-01

    The dc current through an S 1 -S 2 tunnel junction, with Δ 2 greater than Δ 1 , when biased with eV 1 +Δ 2 , will lower the energy in S 1 . This energy reduction will be shared by the phonons and electrons. This device is shown to be analogous to a thermoelectric refrigerator with an effective Peltier coefficient π* approx. Δ 1 /e. Tunneling calculations yield the cooling power P/sub c/, the electrical power P/sub e/ supplied by the bias supply, and the cooling efficiency eta=P/sub c//P/sub e/. The maximum cooling power is obtained for eV= +- (Δ 2 -Δ 1 ) and t 1 =T 1 /T/sub c/1 approx. 0.9. Estimates are made of the temperature difference T 2 -T 1 achievable in Al-Pb and Sn-Pb junctions with an Al 2 O 3 tunneling barrier. The performance of this device is shown to yield a maximum cooling efficiency eta approx. = Δ 1 /(Δ 2 -Δ 1 ) which can be compared with that available in an ideal Carnot refrigerator of eta=T 1 /(T 2 -T 1 ). The development of a useful tunnel-junction refrigerator requires a tunneling barrier with an effective thermal conductance per unit area several orders of magnitude less than that provided by the A1 2 O 3 barrier in the Al-Pb and Sn-Pb systems

  18. Squeezed States in Josephson Junctions.

    Science.gov (United States)

    Hu, X.; Nori, F.

    1996-03-01

    We have studied quantum fluctuation properties of Josephson junctions in the limit of large Josephson coupling energy and small charging energy, when the eigenstates of the system can be treated as being nearly localized. We have considered(X. Hu and F. Nori, preprints.) a Josephson junction in a variety of situations, e.g., coupled to one or several of the following elements: a capacitor, an inductor (in a superconducting ring), and an applied current source. By solving an effective Shrödinger equation, we have obtained squeezed vacuum (coherent) states as the ground states of a ``free-oscillating'' (linearly-driven) Josephson junction, and calculated the uncertainties of its canonical momentum, charge, and coordinate, phase. We have also shown that the excited states of the various systems we consider are similar to the number states of a simple harmonic oscillator but with different fluctuation properties. Furthermore, we have obtained the time-evolution operators for these systems. These operators can make it easier to calculate the time-dependence of the expectation values and fluctuations of various quantities starting from an arbitrary initial state.

  19. About Connections

    Directory of Open Access Journals (Sweden)

    Kathleen S Rockland

    2015-05-01

    Full Text Available Despite the attention attracted by connectomics, one can lose sight of the very real questions concerning What are connections? In the neuroimaging community, structural connectivity is ground truth and underlying constraint on functional or effective connectivity. It is referenced to underlying anatomy; but, as increasingly remarked, there is a large gap between the wealth of human brain mapping and the relatively scant data on actual anatomical connectivity. Moreover, connections have typically been discussed as pairwise, point x projecting to point y (or: to points y and z, or more recently, in graph theoretical terms, as nodes or regions and the interconnecting edges. This is a convenient shorthand, but tends not to capture the richness and nuance of basic anatomical properties as identified in the classic tradition of tracer studies. The present short review accordingly revisits connectional weights, heterogeneity, reciprocity, topography, and hierarchical organization, drawing on concrete examples. The emphasis is on presynaptic long-distance connections, motivated by the intention to probe current assumptions and promote discussions about further progress and synthesis.

  20. Involvement of YAP, TAZ and HSP90 in contact guidance and intercellular junction formation in corneal epithelial cells.

    Directory of Open Access Journals (Sweden)

    Vijay Krishna Raghunathan

    Full Text Available The extracellular environment possesses a rich milieu of biophysical and biochemical signaling cues that are simultaneously integrated by cells and influence cellular phenotype. Yes-associated protein (YAP and transcriptional co-activator with PDZ-binding motif (WWTR1; TAZ, two important signaling molecules of the Hippo pathway, have been recently implicated as nuclear relays of cytoskeletal changes mediated by substratum rigidity and topography. These proteins intersect with other important intracellular signaling pathways (e.g. Wnt and TGFβ. In the cornea, epithelial cells adhere to the stroma through a 3-dimensional topography-rich basement membrane, with features in the nano-submicron size-scale that are capable of profoundly modulating a wide range of fundamental cell behaviors. The influences of substratum-topography, YAP/TAZ knockdown, and HSP90 inhibition on cell morphology, YAP/TAZ localization, and the expression of TGFβ2 and CTGF, were investigated. The results demonstrate (a that knockdown of TAZ enhances contact guidance in a YAP dependent manner, (b that CTGF is predominantly regulated by YAP and not TAZ, and (c that TGFβ2 is regulated by both YAP and TAZ in these cells. Additionally, inhibition of HSP90 resulted in nuclear localization and subsequent transcriptional-activation of YAP, formation of cell-cell junctions and co-localization of E-cadherin and β-catenin at adherens junctions. Results presented in this study reflect the complexities underlying the molecular relationships between the cytoskeleton, growth factors, heat shock proteins, and co-activators of transcription that impact mechanotransduction. The data reveal the importance of YAP/TAZ on the cell behaviors, and gene and protein expression.

  1. HR Connect

    Data.gov (United States)

    US Agency for International Development — HR Connect is the USAID HR personnel system which allows HR professionals to process HR actions related to employee's personal and position information. This system...

  2. Internet Connectivity

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Internet Connectivity. BSNL, SIFY, HCL in Guwahati; only BSNL elsewhere in NE (local player in Shillong). Service poor; All vendors lease BW from BSNL.

  3. High-Q cavity-induced fluxon bunching in inductively coupled Josephson junctions

    DEFF Research Database (Denmark)

    Madsen, S.; Grønbech-Jensen, Niels; Pedersen, Niels Falsig

    2008-01-01

    We consider fluxon dynamics in a stack of inductively coupled long Josephson junctions connected capacitively to a common resonant cavity at one of the boundaries. We study, through theoretical and numerical analyses, the possibility for the cavity to induce a transition from the energetically...

  4. Tunneling properties of Bi2 Sr2 Ca Cu2 Ox/Ag junction

    International Nuclear Information System (INIS)

    Chiang, Yu.N.; Shevchenko, O.B.; Nalbat, Yu.S.

    1993-01-01

    The tunnel-type junction which is naturally formed during firing of Ag paste on the surface of Bi-Sr-Ca-Cu-O crystal has been investigated. It was found that the contact exhibit less than the bulk one in the HTSC. We connect the low gap parameter value with the surface superconductivity in Ag induced by the proximity effect

  5. Electron transfer dynamics of bistable single-molecule junctions

    DEFF Research Database (Denmark)

    Danilov, A.V; Kubatkin, S.; Kafanov, S. G.

    2006-01-01

    We present transport measurements of single-molecule junctions bridged by a molecule with three benzene rings connected by two double bonds and with thiol end-groups that allow chemical binding to gold electrodes. The I-V curves show switching behavior between two distinct states. By statistical ...... analysis of the switching events, we show that a 300 meV mode mediates the transition between the two states. We propose that breaking and reformation of a S-H bond in the contact zone between molecule and electrode explains the observed bistability....

  6. [Occipitocervical junction: Aanatomy, craniometry and pathology].

    Science.gov (United States)

    Furtner, J; Woitek, R; Asenbaum, U; Prayer, D; Schueller-Weidekamm, C

    2016-04-01

    The occipitocervical junction comprises of the occiput condyles, the atlas, and the axis. The radiological evaluation of this region is supported by craniometric measurement methods which are based on predefined anatomical landmarks. The main pathologies of the occipitocervical junction are traumatic injuries, congenital anomalies or normal variants, infections, arthropathies, and tumors. In this article, the anatomy of the occipitocervical junction as well as the most important craniometric measurement methods are explained. Moreover various pathologies and similar appearing normal variants are presented.

  7. Method for shallow junction formation

    Science.gov (United States)

    Weiner, Kurt H.

    1996-01-01

    A doping sequence that reduces the cost and complexity of forming source/drain regions in complementary metal oxide silicon (CMOS) integrated circuit technologies. The process combines the use of patterned excimer laser annealing, dopant-saturated spin-on glass, silicide contact structures and interference effects creates by thin dielectric layers to produce source and drain junctions that are ultrashallow in depth but exhibit low sheet and contact resistance. The process utilizes no photolithography and can be achieved without the use of expensive vacuum equipment. The process margins are wide, and yield loss due to contact of the ultrashallow dopants is eliminated.

  8. Josephson junctions as heterodyne detectors

    International Nuclear Information System (INIS)

    Taur, Y.; Claassen, J.H.; Richards, P.L.

    Heterodyne detection with a point-contact Josephson junction has been investigated both experimentally and theoretically. The measured performance of the device at 36 GHz is in good agreement with the theory. By operating vanadium point contacts at 1.4 K, the authors have achieved a single-sideband (SSB) mixer noise temperature of 54 K with a conversion gain of 1.35 and a signal bandwidth on the order of 1 GHz. A potentially impressive performance for these devices at submillimeter wavelengths can be extrapolated from the results

  9. Josephson junctions as heterodyne detectors

    International Nuclear Information System (INIS)

    Taur, Y.; Claassen, J.H.; Richards, P.L.

    1974-01-01

    Heterodyne detection with a point-contact Josephson junction has been investigated both experimentally and theoretically. The measured performance of the device at 36 GHz is in good agreement with the theory. By operating vanadium point contacts at 1.4 K, a single-sideband (SSB) mixer noise temperature of 54 K with a conversion gain of 1.35 and a signal bandwidth on the order of 1 GHz has been achieved. From the results one can extrapolate a potentially impressive performance for these devices at submillimeter wavelengths

  10. Graphene Josephson Junction Microwave Detector

    Science.gov (United States)

    Fong, Kin Chung; Walsh, Evan; Lee, Gil-Ho; Efetov, Dmitri; Crossno, Jesse; Ranzani, Leonardo; Ohki, Thomas; Kim, Philip; Englund, Dirk

    Modern readout schemes for superconducting qubits have predominately relied on weak microwave signal detection and discrimination. Most schemes are based on heterodyne or homodyne receiver systems and only a few have demonstrated direct detection of microwave photons. The challenges of direct detection stem from the low energy of microwave photons and existing detector efficiency. We have designed, fabricated, and measured a graphene-based Josephson junction (gJJ) microwave detector. Exploiting its low electronic thermal conductivity and specific heat, an electron temperature rise on the order of 0.1 K due to a time average of about 10 photons in the graphene thermal photodetector is readout via a Josephson junction embedded in an 8 GHz microwave cavity. We will estimate the quantum efficiency and dark count probability of the gJJ microwave single photon detectors. This document does not contain technology or technical data controlled under either the U.S. International Traffic in Arms Regulations or the U.S. Export Administration Regulations.

  11. [The eyelid-cheek junction].

    Science.gov (United States)

    Volpei, Ch; Fernandez, J; Chignon-Sicard, B

    2017-10-01

    The eyelid-cheek junction is a key area which generates many comments: from looking tired to looking good or rested, without forgetting charm, beauty, and a youthful appearance. In spite of many interesting medical and surgical procedures, treating this area is sometimes difficult and results are not always up to our expectations. Standardized blepharoplasty, which has often been improperly used, has shown its limits. Since the latest refinements, lipostructure has revolutionised blepharoplasty and serving as a reference, it has become an established technique. Subperiostal mediofacial lift allows outstanding results at the cost of a certain technical aggressiveness. Aesthetic medicine proposes worthy alternative and/or appropriate complementary solutions. Different procedures we dispose of have been reviewed together with their assets and their limits. A codification of therapeutic indications is proposed. The positioning of the eyelid-cheek clinical junction in relation with the low orbital bone rim influences our strategy in choosing the appropriate technique. Copyright © 2017. Published by Elsevier Masson SAS.

  12. Modelling the effect of gap junctions on tissue-level cardiac electrophysiology

    Directory of Open Access Journals (Sweden)

    Doug Bruce

    2012-08-01

    Full Text Available When modelling tissue-level cardiac electrophysiology, continuum approximations to the discrete cell-level equations are used to maintain computational tractability. One of the most commonly used models is represented by the bidomain equations, the derivation of which relies on a homogenisation technique to construct a suitable approximation to the discrete model. This derivation does not explicitly account for the presence of gap junctions connecting one cell to another. It has been seen experimentally [Rohr, Cardiovasc. Res. 2004] that these gap junctions have a marked effect on the propagation of the action potential, specifically as the upstroke of the wave passes through the gap junction. In this paper we explicitly include gap junctions in a both a 2D discrete model of cardiac electrophysiology, and the corresponding continuum model, on a simplified cell geometry. Using these models we compare the results of simulations using both continuum and discrete systems. We see that the form of the action potential as it passes through gap junctions cannot be replicated using a continuum model, and that the underlying propagation speed of the action potential ceases to match up between models when gap junctions are introduced. In addition, the results of the discrete simulations match the characteristics of those shown in Rohr 2004. From this, we suggest that a hybrid model — a discrete system following the upstroke of the action potential, and a continuum system elsewhere — may give a more accurate description of cardiac electrophysiology.

  13. Electrical conduction of Si/indium tin oxide/Si junctions fabricated by surface activated bonding

    Science.gov (United States)

    Liang, Jianbo; Ogawa, Tomoki; Hara, Tomoya; Araki, Kenji; Kamioka, Takefumi; Shigekawa, Naoteru

    2018-02-01

    The electrical properties of n+-Si//indium tin oxide (ITO)/n+-Si, n+-Si//ITO/p+-Si, and p+-Si//ITO/n+-Si junctions fabricated by surface activated bonding (SAB) were investigated. The current-voltage (I-V) characteristics of n+-Si//ITO/n+-Si, n+-Si//ITO/p+-Si, and p+-Si//ITO/n+-Si junctions showed excellent linear properties. The interface resistances of n+-Si//ITO/n+-Si, n+-Si//ITO/p+-Si, and p+-Si//ITO/n+-Si junctions were found to be 0.030, 0.025, and 0.029 Ω·cm2, respectively, which are lower than required for concentrator photovoltaics. The interface resistances of all the junctions increased with increasing annealing temperature. The degradation of the interface resistance is lower in n+-Si//ITO/n+-Si junctions than in n+-Si//ITO/p+-Si and p+-Si//ITO/n+-Si junctions, when the annealing temperature is higher than 100 °C. These results demonstrate that the ITO thin film as an intermediate layer has high potential application for the connection of subcells in the fabrication of tandem solar cells.

  14. Mic13 Is Essential for Formation of Crista Junctions in Mammalian Cells.

    Science.gov (United States)

    Anand, Ruchika; Strecker, Valentina; Urbach, Jennifer; Wittig, Ilka; Reichert, Andreas S

    2016-01-01

    Mitochondrial cristae are connected to the inner boundary membrane via crista junctions which are implicated in the regulation of oxidative phosphorylation, apoptosis, and import of lipids and proteins. The MICOS complex determines formation of crista junctions. We performed complexome profiling and identified Mic13, also termed Qil1, as a subunit of the MICOS complex. We show that MIC13 is an inner membrane protein physically interacting with MIC60, a central subunit of the MICOS complex. Using the CRISPR/Cas method we generated the first cell line deleted for MIC13. These knockout cells show a complete loss of crista junctions demonstrating that MIC13 is strictly required for the formation of crista junctions. MIC13 is required for the assembly of MIC10, MIC26, and MIC27 into the MICOS complex. However, it is not needed for the formation of the MIC60/MIC19/MIC25 subcomplex suggesting that the latter is not sufficient for crista junction formation. MIC13 is also dispensable for assembly of respiratory chain complexes and for maintaining mitochondrial network morphology. Still, lack of MIC13 resulted in a moderate reduction of mitochondrial respiration. In summary, we show that MIC13 has a fundamental role in crista junction formation and that assembly of respiratory chain supercomplexes is independent of mitochondrial cristae shape.

  15. Mic13 Is Essential for Formation of Crista Junctions in Mammalian Cells.

    Directory of Open Access Journals (Sweden)

    Ruchika Anand

    Full Text Available Mitochondrial cristae are connected to the inner boundary membrane via crista junctions which are implicated in the regulation of oxidative phosphorylation, apoptosis, and import of lipids and proteins. The MICOS complex determines formation of crista junctions. We performed complexome profiling and identified Mic13, also termed Qil1, as a subunit of the MICOS complex. We show that MIC13 is an inner membrane protein physically interacting with MIC60, a central subunit of the MICOS complex. Using the CRISPR/Cas method we generated the first cell line deleted for MIC13. These knockout cells show a complete loss of crista junctions demonstrating that MIC13 is strictly required for the formation of crista junctions. MIC13 is required for the assembly of MIC10, MIC26, and MIC27 into the MICOS complex. However, it is not needed for the formation of the MIC60/MIC19/MIC25 subcomplex suggesting that the latter is not sufficient for crista junction formation. MIC13 is also dispensable for assembly of respiratory chain complexes and for maintaining mitochondrial network morphology. Still, lack of MIC13 resulted in a moderate reduction of mitochondrial respiration. In summary, we show that MIC13 has a fundamental role in crista junction formation and that assembly of respiratory chain supercomplexes is independent of mitochondrial cristae shape.

  16. Gendered Connections

    DEFF Research Database (Denmark)

    Jensen, Steffen Bo

    2009-01-01

    This article explores the gendered nature of urban politics in Cape Town by focusing on a group of female, township politicians. Employing the Deleuzian concept of `wild connectivity', it argues that these politically entrepreneurial women were able to negotiate a highly volatile urban landscape...... space also drew on quite traditional notions of female respectability. Furthermore, the article argues, the form of wild connectivity to an extent was a function of the political transition, which destabilized formal structures of gendered authority. It remains a question whether this form...

  17. Connected Traveler

    Energy Technology Data Exchange (ETDEWEB)

    2016-06-01

    The Connected Traveler framework seeks to boost the energy efficiency of personal travel and the overall transportation system by maximizing the accuracy of predicted traveler behavior in response to real-time feedback and incentives. It is anticipated that this approach will establish a feedback loop that 'learns' traveler preferences and customizes incentives to meet or exceed energy efficiency targets by empowering individual travelers with information needed to make energy-efficient choices and reducing the complexity required to validate transportation system energy savings. This handout provides an overview of NREL's Connected Traveler project, including graphics, milestones, and contact information.

  18. Connecting Grammaticalisation

    DEFF Research Database (Denmark)

    Nørgård-Sørensen, Jens; Heltoft, Lars; Schøsler, Lene

    This monograph presents a view on grammaticalisation radically different from standard views centering around the cline of grammaticality. Grammar is seen as a complex sign system, and, as a consequence, grammatical change always comprises semantic change. What unites morphology, topology (word...... morphological, topological and constructional paradigms often connect to form complex paradigms. The book introduces the concept of connecting grammaticalisation to describe the formation, restructuring and dismantling of such complex paradigms. Drawing primarily on data from Germanic, Romance and Slavic...... languages, the book offers both a broad general discussion of theoretical issues (part one) and three case studies (part two)....

  19. Multiplication in Silicon p-n Junctions

    DEFF Research Database (Denmark)

    Moll, John L.

    1965-01-01

    Multiplication values were measured in the collector junctions of silicon p-n-p and n-p-n transistors before and after bombardment by 1016 neutrons/cm2. Within experimental error there was no change either in junction fields, as deduced from capacitance measurements, or in multiplication values...

  20. Gap junctions and connexin-interacting proteins

    NARCIS (Netherlands)

    Giepmans, Ben N G

    2004-01-01

    Gap junctions form channels between adjacent cells. The core proteins of these channels are the connexins. Regulation of gap junction communication (GJC) can be modulated by connexin-associating proteins, such as regulatory protein phosphatases and protein kinases, of which c-Src is the

  1. Get Connected

    Science.gov (United States)

    Horton, Jessica; Hagevik, Rita; Adkinson, Bennett; Parmly, Jilynn

    2013-01-01

    Technology can be both a blessing and a curse in the classroom. Although technology can provide greater access to information and increase student engagement, if screen time replaces time spent outside, then students stand to lose awareness and connectivity to the surrounding natural environment. This article describes how Google Earth can foster…

  2. Getting Connected

    Science.gov (United States)

    Larkin, Patrick

    2011-01-01

    That the world outside schools is changing faster than ever is old news. Unfortunately, that the world "inside" schools is changing at a glacial pace is even older news. As school leaders, principals have an important choice to make as they move into the second decade of the 21st century. School leaders have a moral obligation to connect and…

  3. Making connections

    NARCIS (Netherlands)

    Marion Duimel

    2007-01-01

    Original title: Verbinding maken; senioren en internet. More and more older people are finding their way to the Internet. Many people aged over 50 who have only recently gone online say that a new world has opened up for them. By connecting to the Internet they have the feeling that they

  4. Creating Connections

    Science.gov (United States)

    Ellison, Ann

    2009-01-01

    In this article, the author talks about the Connections Camp, an innovative therapeutic social skill development program designed to meet the unique needs of youth with autism spectrum disorders (ASD). For six weeks each summer, youth ages 5-18 have fun while developing skills that lead to improved communication, better coping strategies, and…

  5. CMS Connect

    Science.gov (United States)

    Balcas, J.; Bockelman, B.; Gardner, R., Jr.; Hurtado Anampa, K.; Jayatilaka, B.; Aftab Khan, F.; Lannon, K.; Larson, K.; Letts, J.; Marra Da Silva, J.; Mascheroni, M.; Mason, D.; Perez-Calero Yzquierdo, A.; Tiradani, A.

    2017-10-01

    The CMS experiment collects and analyzes large amounts of data coming from high energy particle collisions produced by the Large Hadron Collider (LHC) at CERN. This involves a huge amount of real and simulated data processing that needs to be handled in batch-oriented platforms. The CMS Global Pool of computing resources provide +100K dedicated CPU cores and another 50K to 100K CPU cores from opportunistic resources for these kind of tasks and even though production and event processing analysis workflows are already managed by existing tools, there is still a lack of support to submit final stage condor-like analysis jobs familiar to Tier-3 or local Computing Facilities users into these distributed resources in an integrated (with other CMS services) and friendly way. CMS Connect is a set of computing tools and services designed to augment existing services in the CMS Physics community focusing on these kind of condor analysis jobs. It is based on the CI-Connect platform developed by the Open Science Grid and uses the CMS GlideInWMS infrastructure to transparently plug CMS global grid resources into a virtual pool accessed via a single submission machine. This paper describes the specific developments and deployment of CMS Connect beyond the CI-Connect platform in order to integrate the service with CMS specific needs, including specific Site submission, accounting of jobs and automated reporting to standard CMS monitoring resources in an effortless way to their users.

  6. Places Connected:

    DEFF Research Database (Denmark)

    Hansen, Annette Skovsted

    experiences of place, however, when it is often the same people who experience many different places? Along with many other so-called donors in the 1950s, Denmark and Japan chose to invest in the education of own and other nationals involved in development and thereby financed personal connections between...

  7. Quantum synchronization effects in intrinsic Josephson junctions

    International Nuclear Information System (INIS)

    Machida, M.; Kano, T.; Yamada, S.; Okumura, M.; Imamura, T.; Koyama, T.

    2008-01-01

    We investigate quantum dynamics of the superconducting phase in intrinsic Josephson junctions of layered high-T c superconductors motivated by a recent experimental observation for the switching rate enhancement in the low temperature quantum regime. We pay attention to only the capacitive coupling between neighboring junctions and perform large-scale simulations for the Schroedinger equation derived from the Hamiltonian considering the capacitive coupling alone. The simulation focuses on an issue whether the switching of a junction induces those of the other junctions or not. The results reveal that the superconducting phase dynamics show synchronous behavior with increasing the quantum character, e.g., decreasing the junction plane area and effectively the temperature. This is qualitatively consistent with the experimental result

  8. Overlap junctions for high coherence superconducting qubits

    Science.gov (United States)

    Wu, X.; Long, J. L.; Ku, H. S.; Lake, R. E.; Bal, M.; Pappas, D. P.

    2017-07-01

    Fabrication of sub-micron Josephson junctions is demonstrated using standard processing techniques for high-coherence, superconducting qubits. These junctions are made in two separate lithography steps with normal-angle evaporation. Most significantly, this work demonstrates that it is possible to achieve high coherence with junctions formed on aluminum surfaces cleaned in situ by Ar plasma before junction oxidation. This method eliminates the angle-dependent shadow masks typically used for small junctions. Therefore, this is conducive to the implementation of typical methods for improving margins and yield using conventional CMOS processing. The current method uses electron-beam lithography and an additive process to define the top and bottom electrodes. Extension of this work to optical lithography and subtractive processes is discussed.

  9. Cranio-vertebral junction tuberculosis

    Directory of Open Access Journals (Sweden)

    Rajkumar

    2012-01-01

    Full Text Available There are variety of diseases which affect the region of craniovertebral junction, including congenital, malignant lesions, traumatic and infective/inflammatory lesions. CVJ tuberculosis is an extremely rare condition, accounting for 0.3 to 1% of all cases of spinal TB. Few case series have been reported in the literature about this rare condition, but there appears to be lack of consensus even on basic issues like whether to undertake surgical intervention or prefer a conservative approach in cases of CVJ TB. These cases can present with a myriad of symptoms and one needs to have a high index of suspicion for early diagnosis. Early diagnosis and treatment is very important for a favorable outcome. In this article, we have tried to review the available literature and also share our experience about this condition so as to have a better understanding of the disease process and have a more rational treatment protocol.

  10. Josephson tunnel junction microwave attenuator

    DEFF Research Database (Denmark)

    Koshelets, V. P.; Shitov, S. V.; Shchukin, A. V.

    1993-01-01

    A new element for superconducting electronic circuitry-a variable attenuator-has been proposed, designed, and successfully tested. The principle of operation is based on the change in the microwave impedance of a superconductor-insulator-superconductor (SIS) Josephson tunnel junction when dc biased...... at different points in the current-voltage characteristic. Both numerical calculations based on the Tien-Gordon theory and 70-GHz microwave experiments have confirmed the wide dynamic range (more than 15-dB attenuation for one stage) and the low insertion loss in the ''open'' state. The performance of a fully...... integrated submillimeter receiver circuit which comprises a flux-flow oscillator (FFO) as local oscillator, a superconducting variable attenuator, and a microwave SIS detector with tuned-out capacitance is also reported....

  11. Resonance Transport of Graphene Nanoribbon T-Shaped Junctions

    International Nuclear Information System (INIS)

    Xiao-Lan, Kong; Yong-Jian, Xiong

    2010-01-01

    We investigate the transport properties of T-shaped junctions composed of armchair graphene nanoribbons of different widths. Three types of junction geometries are considered. The junction conductance strongly depends on the atomic features of the junction geometry. When the shoulders of the junction have zigzag type edges, sharp conductance resonances usually appear in the low energy region around the Dirac point, and a conductance gap emerges. When the shoulders of the junction have armchair type edges, the conductance resonance behavior is weakened significantly, and the metal-metal-metal junction structures show semimetallic behaviors. The contact resistance also changes notably due to the various interface geometries of the junction

  12. Palladium electrodes for molecular tunnel junctions

    International Nuclear Information System (INIS)

    Chang Shuai; Sen Suman; Zhang Peiming; Gyarfas, Brett; Ashcroft, Brian; Lindsay, Stuart; Lefkowitz, Steven; Peng Hongbo

    2012-01-01

    Gold has been the metal of choice for research on molecular tunneling junctions, but it is incompatible with complementary metal–oxide–semiconductor fabrication because it forms deep level traps in silicon. Palladium electrodes do not contaminate silicon, and also give higher tunnel current signals in the molecular tunnel junctions that we have studied. The result is cleaner signals in a recognition-tunneling junction that recognizes the four natural DNA bases as well as 5-methyl cytosine, with no spurious background signals. More than 75% of all the recorded signal peaks indicate the base correctly. (paper)

  13. Shot noise in YBCO bicrystal Josephson junctions

    DEFF Research Database (Denmark)

    Constantinian, K.Y.; Ovsyannikov, G.A.; Borisenko, I.V.

    2003-01-01

    We measured spectral noise density in YBCO symmetric bicrystal Josephson junctions on sapphire substrates at bias voltages up to 100 mV and T 4.2 K. Normal state resistance of the Josephson junctions, R-N = 20-90 Omega and ICRN up to 2.2 mV have been observed in the experimental samples. Noise...... may explain the experimentally measured linewidth broadening of Josephson oscillations at mm and submm wave frequencies in high-Tc superconducting junctions. Experimental results are discussed in terms of bound states existing at surfaces of d-wave superconducting electrodes....

  14. Soliton excitations in Josephson tunnel junctions

    DEFF Research Database (Denmark)

    Lomdahl, P. S.; Sørensen, O. H.; Christiansen, Peter Leth

    1982-01-01

    A detailed numerical study of a sine-Gordon model of the Josephson tunnel junction is compared with experimental measurements on junctions with different L / λJ ratios. The soliton picture is found to apply well on both relatively long (L / λJ=6) and intermediate (L / λJ=2) junctions. We find good...... agreement for the current-voltage characteristics, power output, and for the shape and height of the zero-field steps (ZFS). Two distinct modes of soliton oscillations are observed: (i) a bunched or congealed mode giving rise to the fundamental frequency f1 on all ZFS's and (ii) a "symmetric" mode which...

  15. Parametric frequency conversion in long Josephson junctions

    International Nuclear Information System (INIS)

    Irie, F.; Ashihara, S.; Yoshida, K.

    1976-01-01

    Current steps at voltages corresponding to the parametric coupling between an applied r.f. field and junction resonant modes have been observed in long Josephson tunnel junctions in the flux-flow state. The observed periodic variations of the step height due to the applied magnetic field are explained quantitatively by a perturbational analysis using Josephson phase equations. The present study demonstrates that the moving vortex array can serve as a coherent pump wave for signal waves propagating in the barrier region, which indicates, as a result, the possibility of traveling-wave parametric devices with long Josephson tunnel junctions. (author)

  16. Microscopic tunneling theory of long Josephson junctions

    DEFF Research Database (Denmark)

    Grønbech-Jensen, N.; Hattel, Søren A.; Samuelsen, Mogens Rugholm

    1992-01-01

    We present a numerical scheme for solving a nonlinear partial integro-differential equation with nonlocal time dependence. The equation describes the dynamics in a long Josephson junction modeled by use of the microscopic theory for tunneling between superconductors. We demonstrate that the detai......We present a numerical scheme for solving a nonlinear partial integro-differential equation with nonlocal time dependence. The equation describes the dynamics in a long Josephson junction modeled by use of the microscopic theory for tunneling between superconductors. We demonstrate...... that the detailed behavior of a solitonic mode (fluxon dynamics) in the junction is different from the results of the conventional perturbed sine-Gordon model....

  17. delta-biased Josephson tunnel junctions

    DEFF Research Database (Denmark)

    Monaco, R.; Mygind, Jesper; Koshelet, V.

    2010-01-01

    Abstract: The behavior of a long Josephson tunnel junction drastically depends on the distribution of the dc bias current. We investigate the case in which the bias current is fed in the central point of a one-dimensional junction. Such junction configuration has been recently used to detect...... the persistent currents circulating in a superconducting loop. Analytical and numerical results indicate that the presence of fractional vortices leads to remarkable differences from the conventional case of uniformly distributed dc bias current. The theoretical findings are supported by detailed measurements...

  18. Connecting dots

    DEFF Research Database (Denmark)

    Murakami, Kyoko; Jacobs, Rachel L.

    2017-01-01

    the family history. We explore how intergenerational relationships are formed through associations with membership categories and reveal how vital information is passed onto future generations. Unlike conventional reminiscence used for therapeutic purposes, family reminiscence is a discursive practice...... of connecting the dots of recalled moments of individual family members lives and is geared towards building a family’s shared future for posterity. Lastly, we consider a wider implication of family reminiscence in terms of human development. http://www.infoagepub.com/products/Memory-Practices-and-Learning...

  19. Proximal tendon-prosthesis junction for active tendon implants of the hand: a biomechanical comparison of 2 techniques.

    Science.gov (United States)

    Thompson, Matthew J; Owen, John R; McDowell, Charles L; Wayne, Jennifer S

    2015-01-01

    To study the biomechanical characteristics (percent stretch, stiffness, and ultimate load) of 2 tendon-prosthesis techniques used to connect the proximal tendon stump to silicone active tendon implants used in reconstruction of flexor tendons. We evaluated percent stretch following cyclic loading and at failure, stiffness during load to failure, and ultimate load of 16 tendon-prosthesis junctions using cadaveric canine flexor digitorum profundus tendons to re-create 2 junction techniques: the tendon loop (TL) and the polyester weave (PW). The TL junction showed greater percent stretch at a static load of 2 N, following 500 cycles of loading between 2 N and 50 N, and at peak load. The PW junction displayed greater stiffness from 50 to 150 N during load to failure. Both junctions failed at a mean ultimate load greater than 220 N. The described proximal junction techniques for active tendon implants were strong enough to resist early active motion in the immediate postoperative period without significant elongation. The PW technique displayed greater stiffness and ultimate load compared with the TL. Data on tendon-prosthesis characteristics of these 2 methods may aid the surgeon in choosing which junction technique to use, during surgical tensioning decisions, and in considering activity protocols after surgery. These data may also serve as a baseline for further investigations regarding active tendon implants. Copyright © 2015 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

  20. Energy-band dynamics in a current-biased Josephson junction probed by incoherent Cooper-pair tunneling

    Energy Technology Data Exchange (ETDEWEB)

    Leppaekangas, Juha; Thuneberg, Erkki [Department of Physical Sciences, University of Oulu, FI-90014 (Finland)], E-mail: juha.leppakangas@oulu.fi

    2009-02-01

    We analyze how the dynamics in a current-biased mesoscopic Josephson junction can be probed by an additional smaller Josephson junction (probe). The probe is connected to a small island in between the Josephson junction and a resistor R >> R{sub Q} = h/4e{sup 2}. The current through the resistor results in an effective current bias to the larger JJ. We model the steady state properties of the system under thermal and quantum fluctuations of the feed current. We use a density matrix approach based on the Born-Markov equations treating the current fluctuations perturbatively. The probe is also treated perturbatively assuming the regime of incoherent Cooper-pair tunneling. We find that the I - V characteristics across the probe shows traces of energy bands, Bloch oscillations and Zener tunneling in the current-biased Josephson junction.

  1. Cut-loading: a useful tool for examining the extent of gap junction tracer coupling between retinal neurons.

    Science.gov (United States)

    Choi, Hee Joo; Ribelayga, Christophe P; Mangel, Stuart C

    2012-01-12

    In addition to chemical synaptic transmission, neurons that are connected by gap junctions can also communicate rapidly via electrical synaptic transmission. Increasing evidence indicates that gap junctions not only permit electrical current flow and synchronous activity between interconnected or coupled cells, but that the strength or effectiveness of electrical communication between coupled cells can be modulated to a great extent(1,2). In addition, the large internal diameter (~1.2 nm) of many gap junction channels permits not only electric current flow, but also the diffusion of intracellular signaling molecules and small metabolites between interconnected cells, so that gap junctions may also mediate metabolic and chemical communication. The strength of gap junctional communication between neurons and its modulation by neurotransmitters and other factors can be studied by simultaneously electrically recording from coupled cells and by determining the extent of diffusion of tracer molecules, which are gap junction permeable, but not membrane permeable, following iontophoretic injection into single cells. However, these procedures can be extremely difficult to perform on neurons with small somata in intact neural tissue. Numerous studies on electrical synapses and the modulation of electrical communication have been conducted in the vertebrate retina, since each of the five retinal neuron types is electrically connected by gap junctions(3,4). Increasing evidence has shown that the circadian (24-hour) clock in the retina and changes in light stimulation regulate gap junction coupling(3-8). For example, recent work has demonstrated that the retinal circadian clock decreases gap junction coupling between rod and cone photoreceptor cells during the day by increasing dopamine D2 receptor activation, and dramatically increases rod-cone coupling at night by reducing D2 receptor activation(7,8). However, not only are these studies extremely difficult to perform on

  2. From four- to two-channel Kondo effect in junctions of XY spin chains

    Directory of Open Access Journals (Sweden)

    Domenico Giuliano

    2016-08-01

    Full Text Available We consider the Kondo effect in Y-junctions of anisotropic XY models in an applied magnetic field along the critical lines characterized by a gapless excitation spectrum. We find that, while the boundary interaction Hamiltonian describing the junction can be recasted in the form of a four-channel, spin-1/2 antiferromagnetic Kondo Hamiltonian, the number of channels effectively participating in the Kondo effect depends on the chain parameters, as well as on the boundary couplings at the junction. The system evolves from an effective four-channel topological Kondo effect for a junction of XX-chains with symmetric boundary couplings into a two-channel one at a junction of three quantum critical Ising chains. The effective number of Kondo channels depends on the properties of the boundary and of the bulk. The XX-line is a “critical” line, where a four-channel topological Kondo effect can be recovered by fine-tuning the boundary parameter, while along the line in parameter space connecting the XX-line and the critical Ising point the junction is effectively equivalent to a two-channel topological Kondo Hamiltonian. Using a renormalization group approach, we determine the flow of the boundary couplings, which allows us to define and estimate the critical couplings and Kondo temperatures of the different Kondo (pair channels. Finally, we study the local transverse magnetization in the center of the Y-junction, eventually arguing that it provides an effective tool to monitor the onset of the two-channel Kondo effect.

  3. Transparency of atom-sized superconducting junctions

    International Nuclear Information System (INIS)

    Van-der-Post, N.; Peters, E.T.; Van Ruitenbeek, J.M.; Yanson, I.K.

    1995-01-01

    We discuss the transparency of atom-size superconducting tunnel junctions by comparing experimental values of the normal resistance and Subgap Structure with the theoretical predictions for these phenomena by Landauer's formula and Multiple Andreev Reflection, respectively

  4. Josephson tunnel junctions in niobium films

    International Nuclear Information System (INIS)

    Wiik, Tapio.

    1976-12-01

    A method of fabricating stable Josephson tunnel junctions with reproducible characteristics is described. The junctions have a sandwich structure consisting of a vacuum evaporated niobium film, a niobium oxide layer produced by the glow discharge method and a lead film deposited by vacuum evaporation. Difficulties in producing thin-film Josephson junctions are discussed. Experimental results suggest that the lower critical field of the niobium film is the most essential parameter when evaluating the quality of these junctions. The dependence of the lower critical field on the film thickness and on the Ginzburg-Landau parameter of the film is studied analytically. Comparison with the properties of the evaporated films and with the previous calculations for bulk specimens shows that the presented model is applicable for most of the prepared samples. (author)

  5. Chirality effect in disordered graphene ribbon junctions

    International Nuclear Information System (INIS)

    Long Wen

    2012-01-01

    We investigate the influence of edge chirality on the electronic transport in clean or disordered graphene ribbon junctions. By using the tight-binding model and the Landauer-Büttiker formalism, the junction conductance is obtained. In the clean sample, the zero-magnetic-field junction conductance is strongly chirality-dependent in both unipolar and bipolar ribbons, whereas the high-magnetic-field conductance is either chirality-independent in the unipolar or chirality-dependent in the bipolar ribbon. Furthermore, we study the disordered sample in the presence of magnetic field and find that the junction conductance is always chirality-insensitive for both unipolar and bipolar ribbons with adequate disorders. In addition, the disorder-induced conductance plateaus can exist in all chiral bipolar ribbons provided the disorder strength is moderate. These results suggest that we can neglect the effect of edge chirality in fabricating electronic devices based on the magnetotransport in a disordered graphene ribbon. (paper)

  6. Persistent junctional reciprocating tachycardia in the fetus

    NARCIS (Netherlands)

    Oudijk, M. A.; Stoutenbeek, P.; Sreeram, N.; Visser, G. H. A.; Meijboom, E. J.

    2003-01-01

    Persistent junctional reciprocating tachycardia (PJRT) tends to be a persistent arrhythmia and requires aggressive therapeutic management. Diagnosis and management of this infrequently occurring tachycardia in the fetus at an early stage is of importance for the prevention of congestive heart

  7. Josephson junction arrays and superconducting wire networks

    International Nuclear Information System (INIS)

    Lobb, C.J.

    1992-01-01

    Techniques used to fabricate integrated circuits make it possible to construct superconducting networks containing as many as 10 6 wires or Josephson junctions. Such networks undergo phase transitions from resistive high-temperature states to ordered low-resistance low-temperature states. The nature of the phase transition depends strongly on controllable parameters such as the strength of the superconductivity in each wire or junction and the external magnetic field. This paper will review the physics of these phase transitions, starting with the simplest zero-magnetic field case. This leads to a Kosterlitz-Thouless transition when the junctions or wires are weak, and a simple mean-field fransition when the junctions or wires are strong. Rich behavior, resulting from frustration, occurs in the presence of a magnetic field. (orig.)

  8. Scalability of multi-junction organic solar cells for large area organic solar modules

    Science.gov (United States)

    Xiao, Xin; Lee, Kyusang; Forrest, Stephen R.

    2015-05-01

    We investigate the scalability of multi-junction organic photovoltaic cells (OPV) with device areas ranging from 1 mm2 to 1 cm2, as well as 25 cm2 active area solar modules. We find that the series resistance losses in 1 cm2 vs. 1 mm2 OPV cell efficiencies are significantly higher in single junction cells than tandem, triple, and four junction cells due to the lower operating voltage and higher current of the former. Using sub-electrodes to reduce series resistance, the power conversion efficiency (PCE) of multi-junction cells is almost independent of area from 1 mm2 to 1 cm2. Twenty-five, 1 cm2 multi-junction cell arrays are integrated in a module and connected in a series-parallel circuit configuration. A yield of 100% with a deviation of PCE from cell to cell of <10% is achieved. The module generates an output power of 162 ± 9 mW under simulated AM1.5G illumination at one sun intensity, corresponding to PCE = 6.5 ± 0.1%, slightly lower than PCE of discrete cells ranging from 6.7% to 7.2%.

  9. Spinal Gap Junction Channels in Neuropathic Pain

    OpenAIRE

    Jeon, Young Hoon; Youn, Dong Ho

    2015-01-01

    Damage to peripheral nerves or the spinal cord is often accompanied by neuropathic pain, which is a complex, chronic pain state. Increasing evidence indicates that alterations in the expression and activity of gap junction channels in the spinal cord are involved in the development of neuropathic pain. Thus, this review briefly summarizes evidence that regulation of the expression, coupling, and activity of spinal gap junction channels modulates pain signals in neuropathic pain states induced...

  10. Construction of tunable peptide nucleic acid junctions.

    Science.gov (United States)

    Duan, Tanghui; He, Liu; Tokura, Yu; Liu, Xin; Wu, Yuzhou; Shi, Zhengshuang

    2018-03-15

    We report here the construction of 3-way and 4-way peptide nucleic acid (PNA) junctions as basic structural units for PNA nanostructuring. The incorporation of amino acid residues into PNA chains makes PNA nanostructures with more structural complexity and architectural flexibility possible, as exemplified by building 3-way PNA junctions with tunable nanopores. Given that PNA nanostructures have good thermal and enzymatic stabilities, they are expected to have broad potential applications in biosensing, drug delivery and bioengineering.

  11. 78 FR 55684 - ConnectED Workshop

    Science.gov (United States)

    2013-09-11

    ... connecting virtually all K-12 students in the United States to next- generation broadband. This Notice...'s ConnectED initiative would bring next-generation Internet speeds to K-12 schools across the nation... schools for digital learning. The ConnectED Workshop will discuss the growing bandwidth needs of K-12...

  12. Junction depth measurement using carrier illumination

    International Nuclear Information System (INIS)

    Borden, Peter

    2001-01-01

    Carrier Illumination [trade mark] (CI) is a new method recently developed to meet the need for a non-destructive, high throughput junction depth measurement on patterned wafers. A laser beam creates a quasi-static excess carrier profile in the semiconductor underlying the activated junction. The excess carrier profile is fairly constant below the junction, and drops rapidly in the junction, creating a steep index of refraction gradient at the junction edge. Interference with light reflected from this index gradient provides a signal that is analyzed to determine the junction depth. The paper summarizes evaluation of performance in full NMOS and PMOS process flows, on both bare and patterned wafers. The aims have been to validate (1) performance in the presence of underlying layers typically found at the source/drain (S/D) process steps and (2) measurement on patterned wafers. Correlation of CI measurements to SIMS and transistor drive current are shown. The data were obtained from NMOS structures using As S/D and LDD implants. Correlations to SRP, SIMS and sheet resistance are shown for PMOS structures using B 11 LDD implants. Gage capability measurements are also presented

  13. Ballistic Josephson junctions based on CVD graphene

    Science.gov (United States)

    Li, Tianyi; Gallop, John; Hao, Ling; Romans, Edward

    2018-04-01

    Josephson junctions with graphene as the weak link between superconductors have been intensely studied in recent years, with respect to both fundamental physics and potential applications. However, most of the previous work was based on mechanically exfoliated graphene, which is not compatible with wafer-scale production. To overcome this limitation, we have used graphene grown by chemical vapour deposition (CVD) as the weak link of Josephson junctions. We demonstrate that very short, wide CVD-graphene-based Josephson junctions with Nb electrodes can work without any undesirable hysteresis in their electrical characteristics from 1.5 K down to a base temperature of 320 mK, and their gate-tuneable critical current shows an ideal Fraunhofer-like interference pattern in a perpendicular magnetic field. Furthermore, for our shortest junctions (50 nm in length), we find that the normal state resistance oscillates with the gate voltage, consistent with the junctions being in the ballistic regime, a feature not previously observed in CVD-graphene-based Josephson junctions.

  14. Characterization, scaling, and partial representation of diffuse and discrete input junctions to CA3 hippocampus.

    Science.gov (United States)

    Ascarrunz, F G; Kisley, M A; Flach, K A; Hamilton, R W; MacGregor, R J

    1995-07-01

    This paper applies a general mathematical system for characterizing and scaling functional connectivity and information flow across the diffuse (EC) and discrete (DG) input junctions to the CA3 hippocampus. Both gross connectivity and coordinated multiunit informational firing patterns are quantitatively characterized in terms of 32 defining parameters interrelated by 17 equations, and then scaled down according to rules for uniformly proportional scaling and for partial representation. The diffuse EC-CA3 junction is shown to be uniformly scalable with realistic representation of both essential spatiotemporal cooperativity and coordinated firing patterns down to populations of a few hundred neurons. Scaling of the discrete DG-CA3 junction can be effected with a two-step process, which necessarily deviates from uniform proportionality but nonetheless produces a valuable and readily interpretable reduced model, also utilizing a few hundred neurons in the receiving population. Partial representation produces a reduced model of only a portion of the full network where each model neuron corresponds directly to a biological neuron. The mathematical analysis illustrated here shows that although omissions and distortions are inescapable in such an application, satisfactorily complete and accurate models the size of pattern modules are possible. Finally, the mathematical characterization of these junctions generates a theory which sees the DG as a definer of the fine structure of embedded traces in the hippocampus and entire coordinated patterns of sequences of 14-cell links in CA3 as triggered by the firing of sequences of individual neurons in DG.

  15. Connecting dots

    DEFF Research Database (Denmark)

    Murakami, Kyoko; Jacobs, Rachel L.

    2017-01-01

    shall present a discursive approach, a methodology that captures the dynamics of reminiscence. We analyse collected conversational data of British family members reminiscing on their past as a joint family activity. Through such talk-in-interaction, the family members develop continuity within...... and Middleton, 1995). A reminiscence conversation is a dynamic talk-in-interaction, which can produce valuable learning experience for the participants involved. Reminiscence talk contains rich, personal, historic data that can reveal and inform family members of an unknown past. In this seminar/chapter, we...... of connecting the dots of recalled moments of individual family members lives and is geared towards building a family’s shared future for posterity. Lastly, we consider a wider implication of family reminiscence in terms of human development. http://www.infoagepub.com/products/Memory-Practices-and-Learning...

  16. Cell culture model predicts human disease: Altered expression of junction proteins and matrix metalloproteinases in cervical dysplasia

    Directory of Open Access Journals (Sweden)

    Kivi Niina

    2012-08-01

    Full Text Available Abstract Background Cervical cancer is necessarily caused by human papillomaviruses, which encode three oncogenes manifesting their functions by interfering with a number of cellular proteins and pathways: the E5, E6, and E7 proteins. We have earlier found in our microarray studies that the E5 oncogene crucially affects the expression of cellular genes involved in adhesion and motility of epithelial cells. Methods In order to biologically validate our previous experimental findings we performed immunohistochemical staining of a representative set of tissue samples from different grades of high-risk human papillomavirus associated cervical disease as well as normal squamous and columnar cervical epithelium. Three-dimensional collagen raft cultures established from E5-expressing and control epithelial cells were also examined. The expression of p16, matrix metalloproteinase (MMP -7, MMP-16, cytokeratin (CK 8/18, laminin, E-cadherin and beta-catenin was studied. Results In agreement with our previous microarray studies, we found intense staining for E-cadherin and beta-catenin in adherens junctions even in high-grade cervical lesions. Staining for MMP-16 was increased in severe disease as well. No significant change in staining for MMP-7 and cytokeratin 8/18 along with the grade of cervical squamous epithelial disease was observed. Conclusions Here we have confirmed, using tissue material from human papillomavirus associated lesions, some of the cellular gene expression modifications that we earlier reported in an experimental system studying specifically the E5 oncogene of papillomaviruses. These findings were partially surprising in the context of cervical carcinogenesis and emphasize that the complexity of carcinogenesis is not yet fully understood. Microarray approaches provide a wide overwiev of gene expression in experimental settings, which may yield biologically valid biomarkers for disease diagnostics, prognosis, and follow-up.

  17. Dynamical photo-induced electronic properties of molecular junctions

    Science.gov (United States)

    Beltako, K.; Michelini, F.; Cavassilas, N.; Raymond, L.

    2018-03-01

    Nanoscale molecular-electronic devices and machines are emerging as promising functional elements, naturally flexible and efficient, for next-generation technologies. A deeper understanding of carrier dynamics in molecular junctions is expected to benefit many fields of nanoelectronics and power devices. We determine time-resolved charge current flowing at the donor-acceptor interface in molecular junctions connected to metallic electrodes by means of quantum transport simulations. The current is induced by the interaction of the donor with a Gaussian-shape femtosecond laser pulse. Effects of the molecular internal coupling, metal-molecule tunneling, and light-donor coupling on photocurrent are discussed. We then define the time-resolved local density of states which is proposed as an efficient tool to describe the absorbing molecule in contact with metallic electrodes. Non-equilibrium reorganization of hybridized molecular orbitals through the light-donor interaction gives rise to two phenomena: the dynamical Rabi shift and the appearance of Floquet-like states. Such insights into the dynamical photoelectronic structure of molecules are of strong interest for ultrafast spectroscopy and open avenues toward the possibility of analyzing and controlling the internal properties of quantum nanodevices with pump-push photocurrent spectroscopy.

  18. Josephson tunnel junctions with ferromagnetic interlayer

    Energy Technology Data Exchange (ETDEWEB)

    Weides, M.P.

    2006-07-01

    Superconductivity and ferromagnetism are well-known physical properties of solid states that have been widely studied and long thought about as antagonistic phenomena due to difference in spin ordering. It turns out that the combination of both superconductor and ferromagnet leads to a very rich and interesting physics. One particular example, the phase oscillations of the superconducting order parameter inside the ferromagnet, will play a major role for the devices discussed in this work. In this thesis, I present Josephson junctions with a thin Al{sub 2}O{sub 3} tunnel barrier and a ferromagnetic interlayer, i.e. superconductor-insulator-ferromagnet-superconductor (SIFS) stacks. The fabrication of junctions was optimized regarding the insulation of electrodes and the homogeneity of the current transport. The junctions were either in the 0 or {pi} coupled ground state, depending on the thickness of the ferromagnetic layer and on temperature. The influence of ferromagnetic layer thickness on the transport properties and the coupling (0, {pi}) of SIFS tunnel junctions was studied. Furthermore, using a stepped ferromagnetic layer with well-chosen thicknesses, I obtained the so-called 0-{pi} Josephson junction. At a certain temperature this 0-{pi} junction can be made perfectly symmetric. In this case the ground state corresponds to a vortex of supercurrent creating a magnetic flux which is a fraction of the magnetic flux quantum {phi}{sub 0}. Such structures allow to study the physics of fractional vortices and to build various electronic circuits based on them. The SIFS junctions presented here have an exponentially vanishing damping at T {yields} 0. The SIFS technology developed within the framework of this work may be used to construct classical and quantum devices such as oscillators, memory cells and qubits. (orig.)

  19. Model Building to Facilitate Understanding of Holliday Junction and Heteroduplex Formation, and Holliday Junction Resolution

    Science.gov (United States)

    Selvarajah, Geeta; Selvarajah, Susila

    2016-01-01

    Students frequently expressed difficulty in understanding the molecular mechanisms involved in chromosomal recombination. Therefore, we explored alternative methods for presenting the two concepts of the double-strand break model: Holliday junction and heteroduplex formation, and Holliday junction resolution. In addition to a lecture and…

  20. Simultaneous description of conductance and thermopower in single-molecule junctions from many-body ab initio calculations

    DEFF Research Database (Denmark)

    Jin, Chengjun; Markussen, Troels; Thygesen, Kristian Sommer

    2014-01-01

    We investigate the electronic conductance and thermopower of a single-molecule junction consisting of bis-(4-aminophenyl) acetylene (B4APA) connected to gold electrodes. We use nonequilibrium Green's function methods in combination with density-functional theory (DFT) and the many-body GW...

  1. An Efficient Solution-Processed Intermediate Layer for Facilitating Fabrication of Organic Multi-Junction Solar Cells

    DEFF Research Database (Denmark)

    Ning Li; Baran, Derya; Forberich, Karen

    2013-01-01

    ):poly(styrenesulfonate) (PEDOT:PSS) is demonstrated for series-connected multi-junction organic solar cells (OSCs). Drying at 80 °C in air is sufficient for this solution-processed IML to obtain excellent functionality and reliability, which allow the use of most of high performance donor materials in the tandem structure...

  2. Increasing gap junctional coupling: a tool for dissecting the role of gap junctions

    DEFF Research Database (Denmark)

    Axelsen, Lene Nygaard; Haugan, Ketil; Stahlhut, Martin

    2007-01-01

    . In a number of cases, gap junctions have been implicated in the initiation and progress of disease, and experimental uncoupling has been used to investigate the exact role of coupling. The inverse approach, i.e., to increase coupling, has become possible in recent years and represents a new way of testing......Much of our current knowledge about the physiological and pathophysiological role of gap junctions is based on experiments where coupling has been reduced by either chemical agents or genetic modification. This has brought evidence that gap junctions are important in many physiological processes...... the role of gap junctions. The aim of this review is to summarize the current knowledge obtained with agents that selectively increase gap junctional intercellular coupling. Two approaches will be reviewed: increasing coupling by the use of antiarrhythmic peptide and its synthetic analogs...

  3. The connection of hydronephrosis and microcirculation deterioration

    Directory of Open Access Journals (Sweden)

    Vorobets Dmytro

    2016-09-01

    Full Text Available In this study, we have analyzed the influence of hydronephrosis upon the microcirculation system, in situations of pyeloureteral junction obstruction. Herein, bulbar conjunctiva has been chosen as the object of this biomicroscopic study because of its simplicity and the method availability in clinic practice. In fulfilling this work, we ascertained the connections between extravascular, intravascular, vascular and general conjunctival indices of the patients before radical and paliatic correction of the pyeloureteral junction obstruction (i.e. by open and laparoscopic pyeloplasty, endopyelotomy, laser resection and balloon dilatation. We concluded that, apart from the proved deterioration of kidney function, systemic deteriorations of microcirculation may be observed in situations of clinically marked hydronephrosis, according to the results of radioisotope renography and excretory urography.

  4. Fluxons in a triangular set of coupled long Josephson junctions

    Energy Technology Data Exchange (ETDEWEB)

    Yukon, Stanford P., E-mail: yukon@alum.mit.edu [Air Force Research Laboratory (United States); Malomed, Boris A. [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel)

    2015-09-15

    We report results of an analysis of the dynamics of magnetic flux solitons in the system of three long Josephson junctions between three bulk superconductors that form a prism. The system is modeled by coupled sine-Gordon equations for the phases of the junctions. The Aharonov-Bohm constraint takes into account the axial magnetic flux enclosed by the prism and reduces the system from three independent phases to two. The equations of motion for the phases include dissipative terms, and a control parameter δ which accounts for the deviation of the enclosed flux from half a quantum. Analyzing the effective potential of the coupled equations, we identify different species of topological and non-topological phase solitons (fluxons) in this system. In particular, subkinks with fractional topological charges ±1/3 and ±2/3, confined inside integer-charge fluxons, may be mapped onto the root diagrams for mesons and baryons in the original quark model of hadrons. Solutions for straight-line kinks and for two types of non-topological solitons are obtained in an explicit analytical form. Numerical tests demonstrate that the former species is unstable against breakup into pairs of separating single-fluxon kinks. The non-topological kinks feature metastability, eventually breaking up into fluxon-antifluxon pairs. Free fractional-fluxon kinks, that connect different potential minima and are, accordingly, pulled by the potential difference, are also considered. Using the momentum-balance method, we predict the velocity at which these kinks should move in the presence of the dissipation. Numerical tests demonstrate that the analysis predicts the velocity quite closely. Higher-energy static solutions for all of the stable kink types mentioned above, as well as kinks connecting false vacua, are found by means of the shooting method. Inelastic collisions among the stable fractional and single-fluxon kinks are investigated numerically.

  5. Regulation of gap junctions by protein phosphorylation

    Directory of Open Access Journals (Sweden)

    J.C. Sáez

    1998-05-01

    Full Text Available Gap junctions are constituted by intercellular channels and provide a pathway for transfer of ions and small molecules between adjacent cells of most tissues. The degree of intercellular coupling mediated by gap junctions depends on the number of gap junction channels and their activity may be a function of the state of phosphorylation of connexins, the structural subunit of gap junction channels. Protein phosphorylation has been proposed to control intercellular gap junctional communication at several steps from gene expression to protein degradation, including translational and post-translational modification of connexins (i.e., phosphorylation of the assembled channel acting as a gating mechanism and assembly into and removal from the plasma membrane. Several connexins contain sites for phosphorylation for more than one protein kinase. These consensus sites vary between connexins and have been preferentially identified in the C-terminus. Changes in intercellular communication mediated by protein phosphorylation are believed to control various physiological tissue and cell functions as well as to be altered under pathological conditions.

  6. Tunnel magnetoresistance in double spin filter junctions

    International Nuclear Information System (INIS)

    Saffarzadeh, Alireza

    2003-01-01

    We consider a new type of magnetic tunnel junction, which consists of two ferromagnetic tunnel barriers acting as spin filters (SFs), separated by a nonmagnetic metal (NM) layer. Using the transfer matrix method and the free-electron approximation, the dependence of the tunnel magnetoresistance (TMR) on the thickness of the central NM layer, bias voltage and temperature in the double SF junction are studied theoretically. It is shown that the TMR and electron-spin polarization in this structure can reach very large values under suitable conditions. The highest value of the TMR can reach 99%. By an appropriate choice of the thickness of the central NM layer, the degree of spin polarization in this structure will be higher than that of the single SF junctions. These results may be useful in designing future spin-polarized tunnelling devices

  7. Josephson junctions with ferromagnetic alloy interlayer

    International Nuclear Information System (INIS)

    Himmel, Nico

    2015-01-01

    Josephson junctions are used as active devices in superconducting electronics and quantum information technology. Outstanding properties are their distinct non-linear electrical characteristics and a usually sinusoidal relation between the current and the superconducting phase difference across the junction. In general the insertion of ferromagnetic material in the barrier of a Josephson junction is associated with a suppression of superconducting correlations. But also new phenomena can arise which may allow new circuit layouts and enhance the performance of applications. This thesis presents a systematic investigation for two concepts to fabricate Josephson junctions with a rather uncommon negative critical current. Such devices exhibit an intrinsic phase slip of π between the electrodes, so they are also known as π junctions. Both studies go well beyond existing experiments and in one system a π junction is shown for the first time. All the thin film junctions are based on superconducting Nb electrodes. In a first approach, barriers made from Si and Fe were investigated with respect to the realisation of π junctions by spin-flip processes. The distribution of Fe in the Si matrix was varied from pure layers to disperse compounds. The systematic fabrication of alloy barriers was facilitated by the development of a novel timing-based combinatorial sputtering technique for planetary deposition systems. An orthogonal gradient approach allowed to create binary layer libraries with independent variations of thickness and composition. Second, Nb vertical stroke AlO x vertical stroke Nb vertical stroke Ni 60 Cu 40 vertical stroke Nb (SIsFS) double barrier junctions were experimentally studied for the occurrence of proximity effect induced order parameter oscillations. Detailed dependencies of the critical current density on the thickness of s-layer and F-layer were acquired and show a remarkable agreement to existing theoretical predictions. Especially a variation of

  8. Phase-dependent noise in Josephson junctions

    Science.gov (United States)

    Sheldon, Forrest; Peotta, Sebastiano; Di Ventra, Massimiliano

    2018-03-01

    In addition to the usual superconducting current, Josephson junctions (JJs) support a phase-dependent conductance related to the retardation effect of tunneling quasi-particles. This introduces a dissipative current with a memory-resistive (memristive) character that should also affect the current noise. By means of the microscopic theory of tunnel junctions we compute the complete current autocorrelation function of a Josephson tunnel junction and show that this memristive component gives rise to both a previously noted phase-dependent thermal noise, and an undescribed non-stationary, phase-dependent dynamic noise. As experiments are approaching ranges in which these effects may be observed, we examine the form and magnitude of these processes. Their phase dependence can be realized experimentally as a hysteresis effect and may be used to probe defects present in JJ based qubits and in other superconducting electronics applications.

  9. Silicon fiber with p-n junction

    Energy Technology Data Exchange (ETDEWEB)

    Homa, D.; Cito, A.; Pickrell, G.; Hill, C.; Scott, B. [Department of Materials Science and Engineering, Virginia Polytechnic Institute and State University, 312 Holden Hall, Blacksburg, Virginia 24060 (United States)

    2014-09-22

    In this study, we fabricated a p-n junction in a fiber with a phosphorous doped silicon core and fused silica cladding. The fibers were fabricated via a hybrid process of the core-suction and melt-draw techniques and maintained overall diameters ranging from 200 to 900 μm and core diameters of 20–800 μm. The p-n junction was formed by doping the fiber with boron and confirmed via the current-voltage characteristic. The demonstration of a p-n junction in a melt-drawn silicon core fiber paves the way for the seamless integration of optical and electronic devices in fibers.

  10. Silicon fiber with p-n junction

    International Nuclear Information System (INIS)

    Homa, D.; Cito, A.; Pickrell, G.; Hill, C.; Scott, B.

    2014-01-01

    In this study, we fabricated a p-n junction in a fiber with a phosphorous doped silicon core and fused silica cladding. The fibers were fabricated via a hybrid process of the core-suction and melt-draw techniques and maintained overall diameters ranging from 200 to 900 μm and core diameters of 20–800 μm. The p-n junction was formed by doping the fiber with boron and confirmed via the current-voltage characteristic. The demonstration of a p-n junction in a melt-drawn silicon core fiber paves the way for the seamless integration of optical and electronic devices in fibers.

  11. Nanomembrane-based mesoscopic superconducting hybrid junctions.

    Science.gov (United States)

    Thurmer, Dominic J; Bof Bufon, Carlos Cesar; Deneke, Christoph; Schmidt, Oliver G

    2010-09-08

    A new method for combining top-down and bottom-up approaches to create superconductor-normal metal-superconductor niobium-based Josephson junctions is presented. Using a rolled-up semiconductor nanomembrane as scaffolding, we are able to create mesoscopic gold filament proximity junctions. These are created by electromigration of gold filaments after inducing an electric field mediated breakdown in the semiconductor nanomembrane, which can generate nanometer sized structures merely using conventional optical lithography techniques. We find that the created point contact junctions exhibit large critical currents of a few milliamps at 4.2 K and an I(c)R(n) product placing their characteristic frequency in the terahertz region. These nanometer-sized filament devices can be further optimized and integrated on a chip for their use in superconductor hybrid electronics circuits.

  12. Ferromagnetic resonance with long Josephson junction

    Science.gov (United States)

    Golovchanskiy, I. A.; Abramov, N. N.; Stolyarov, V. S.; Emelyanova, O. V.; Golubov, A. A.; Ustinov, A. V.; Ryazanov, V. V.

    2017-05-01

    In this work we propose a hybrid device based on a long Josephson junction (JJ) coupled inductively to an external ferromagnetic (FM) layer. The long JJ in a zero-field operation mode induces a localized AC magnetic field in the FM layer and enables a synchronized magnetostatic standing wave. The magnetostatic wave induces additional dissipation for soliton propagation in the junction and also enables a phase locking (resonant soliton synchronization) at a frequency of natural ferromagnetic resonance. The later manifests itself as an additional constant voltage step on the current-voltage characteristics at the corresponding voltage. The proposed device allows to study magnetization dynamics of individual micro-scaled FM samples using just DC technique, and also it provides additional phase locking frequency in the junction, determined exclusively by characteristics of the ferromagnet.

  13. Josephson junctions with ferromagnetic alloy interlayer

    Energy Technology Data Exchange (ETDEWEB)

    Himmel, Nico

    2015-07-23

    Josephson junctions are used as active devices in superconducting electronics and quantum information technology. Outstanding properties are their distinct non-linear electrical characteristics and a usually sinusoidal relation between the current and the superconducting phase difference across the junction. In general the insertion of ferromagnetic material in the barrier of a Josephson junction is associated with a suppression of superconducting correlations. But also new phenomena can arise which may allow new circuit layouts and enhance the performance of applications. This thesis presents a systematic investigation for two concepts to fabricate Josephson junctions with a rather uncommon negative critical current. Such devices exhibit an intrinsic phase slip of π between the electrodes, so they are also known as π junctions. Both studies go well beyond existing experiments and in one system a π junction is shown for the first time. All the thin film junctions are based on superconducting Nb electrodes. In a first approach, barriers made from Si and Fe were investigated with respect to the realisation of π junctions by spin-flip processes. The distribution of Fe in the Si matrix was varied from pure layers to disperse compounds. The systematic fabrication of alloy barriers was facilitated by the development of a novel timing-based combinatorial sputtering technique for planetary deposition systems. An orthogonal gradient approach allowed to create binary layer libraries with independent variations of thickness and composition. Second, Nb vertical stroke AlO{sub x} vertical stroke Nb vertical stroke Ni{sub 60}Cu{sub 40} vertical stroke Nb (SIsFS) double barrier junctions were experimentally studied for the occurrence of proximity effect induced order parameter oscillations. Detailed dependencies of the critical current density on the thickness of s-layer and F-layer were acquired and show a remarkable agreement to existing theoretical predictions. Especially

  14. Strong Josephson Coupling in Planar Graphene Junctions

    Science.gov (United States)

    Park, Jinho; Lee, Gil-Ho; Lee, Jae Hyeong; Takane, Yositake; Imura, Ken-Ichiro; Taniguchi, Takashi; Watanabe, Kenji; Lee, Hu-Jong

    A recent breakthrough of processing graphene, employing encapsulation by hexagonal boron nitride layers (BGB structure), allows realizing the ballistic carrier transport in graphene. Thereafter, ballistic Josephson coupling has been studied by closely edge-contacted BGB structure with two superconducting electrodes. Here, we report on the strong Josephson coupling with planar graphene junction in truly short and ballistic regime. Our device showed high transmission probability and the junction critical current (IC) oscillating for sweeping the gate voltage along with the normal conductance oscillation (Fabry-Perot oscillations), providing a direct evidence for the ballistic nature of the junction pair current. We also observed the convex-upward shape of decreasing critical currents with increasing temperature, canonical properties of the short Josephson coupling. By fitting these curves into theoretical models, we demonstrate the strong Josephson coupling in our devices, which is also supported by the exceptionally large value of ICRN ( 2 Δ / e RNis the normal resistance).

  15. A congenital form of junctional ectopic tachycardia.

    Science.gov (United States)

    Tulino, Domenico; Dattilo, Giuseppe; Tulino, Viviana; Marte, Filippo; Patanè, Salvatore

    2010-11-19

    Accessory pathways have been described as well as their Ecg identification criteria also in pediatric population. Radiofrequency ablation is a curative treatment but its application has been more limited in the paediatric population. The congenital form of junctional ectopic tachycardia was firstly described by Coumel et al. in 1976. It usually occurs in the first six months of life presenting as a persistent sustained form, lasting up to 90% of the time and it is hampered by high mortality. Its clinical presentation may be dramatic, being associated in up to 60% of cases with cardiomegaly and/or heart failure. Secondary dilated cardiomyopathy, ventricular fibrillation and sudden cardiac death have also been reported. We present a case of congenital form of junctional ectopic tachycardia in a 12-day-old newborn infant. Also this case is illustrative of the congenital form of junctional ectopic tachycardia. Copyright © 2008 Elsevier Ireland Ltd. All rights reserved.

  16. Modulation of Asymmetric Flux in Heterotypic Gap Junctions by Pore Shape, Particle Size and Charge.

    Science.gov (United States)

    Mondal, Abhijit; Sachse, Frank B; Moreno, Alonso P

    2017-01-01

    Gap junction channels play a vital role in intercellular communication by connecting cytoplasm of adjoined cells through arrays of channel-pores formed at the common membrane junction. Their structure and properties vary depending on the connexin isoform(s) involved in forming the full gap junction channel. Lack of information on the molecular structure of gap junction channels has limited the development of computational tools for single channel studies. Currently, we rely on cumbersome experimental techniques that have limited capabilities. We have earlier reported a simplified Brownian dynamics gap junction pore model and demonstrated that variations in pore shape at the single channel level can explain some of the differences in permeability of heterotypic channels observed in in vitro experiments. Based on this computational model, we designed simulations to study the influence of pore shape, particle size and charge in homotypic and heterotypic pores. We simulated dye diffusion under whole cell voltage clamping. Our simulation studies with pore shape variations revealed a pore shape with maximal flux asymmetry in a heterotypic pore. We identified pore shape profiles that match the in silico flux asymmetry results to the in vitro results of homotypic and heterotypic gap junction formed out of Cx43 and Cx45. Our simulation results indicate that the channel's pore-shape established flux asymmetry and that flux asymmetry is primarily regulated by the sizes of the conical and/or cylindrical mouths at each end of the pore. Within the set range of particle size and charge, flux asymmetry was found to be independent of particle size and directly proportional to charge magnitude. While particle charge was vital to creating flux asymmetry, charge magnitude only scaled the observed flux asymmetry. Our studies identified the key factors that help predict asymmetry. Finally, we suggest the role of such flux asymmetry in creating concentration imbalances of messenger

  17. Terahertz Responses of Intrinsic Josephson Junctions in High TC Superconductors

    International Nuclear Information System (INIS)

    Wang, H. B.; Wu, P. H.; Yamashita, T.

    2001-01-01

    High frequency responses of intrinsic Josephson junctions up to 2.5THz, including the observation of Shapiro steps under various conditions, are reported and discussed in this Letter. The sample was an array of intrinsic Josephson junctions singled out from inside a high T C superconducting Bi 2 Sr 2 CaCu 2 O 8+x single crystal, with a bow-tie antenna integrated to it. The number of junctions in the array was controllable, the junctions were homogeneous, the distribution of applied irradiation among the junctions was even, and the junctions could synchronously respond to high frequency irradiation

  18. Systematic study of shallow junction formation on germanium substrates

    DEFF Research Database (Denmark)

    Hellings, Geert; Rosseel, Erik; Clarysse, Trudo

    2011-01-01

    Published results on Ge junctions are benchmarked systematically using RS–XJ plots. The electrical activation level required to meet the ITRS targets is calculated. Additionally, new results are presented on shallow furnace-annealed B junctions and shallow laser-annealed As junctions. Co-implanti......Published results on Ge junctions are benchmarked systematically using RS–XJ plots. The electrical activation level required to meet the ITRS targets is calculated. Additionally, new results are presented on shallow furnace-annealed B junctions and shallow laser-annealed As junctions. Co...

  19. West Nile virus-induced disruption of the blood-brain barrier in mice is characterized by the degradation of the junctional complex proteins and increase in multiple matrix metalloproteinases.

    Science.gov (United States)

    Roe, Kelsey; Kumar, Mukesh; Lum, Stephanie; Orillo, Beverly; Nerurkar, Vivek R; Verma, Saguna

    2012-06-01

    West Nile virus (WNV) encephalitis is characterized by neuroinflammation, neuronal loss and blood-brain barrier (BBB) disruption. However, the mechanisms associated with the BBB disruption are unclear. Complex interactions between the tight junction proteins (TJP) and the adherens junction proteins (AJP) of the brain microvascular endothelial cells are responsible for maintaining the BBB integrity. Herein, we characterized the relationship between the BBB disruption and expression kinetics of key TJP, AJP and matrix metalloproteinases (MMPs) in the mice brain. A dramatic increase in the BBB permeability and extravasation of IgG was observed at later time points of the central nervous system (CNS) infection and did not precede virus-CNS entry. WNV-infected mice exhibited significant reduction in the protein levels of the TJP ZO-1, claudin-1, occludin and JAM-A, and AJP β-catenin and vascular endothelial cadherin, which correlated with increased levels of MMP-1, -3 and -9 and infiltrated leukocytes in the brain. Further, intracranial inoculation of WNV also demonstrated increased extravasation of IgG in the brain, suggesting the role of virus replication in the CNS in BBB disruption. These data suggest that altered expression of junction proteins is a pathological event associated with WNV infection and may explain the molecular basis of BBB disruption. We propose that WNV initially enters CNS without altering the BBB integrity and later virus replication in the brain initiates BBB disruption, allowing enhanced infiltration of immune cells and contribute to virus neuroinvasion via the 'Trojan-horse' route. These data further implicate roles of multiple MMPs in the BBB disruption and strategies to interrupt this process may influence the WNV disease outcome.

  20. Structure and function of gap junction proteins: role of gap junction proteins in embryonic heart development.

    Science.gov (United States)

    Ahir, Bhavesh K; Pratten, Margaret K

    2014-01-01

    Intercellular (cell-to-cell) communication is a crucial and complex mechanism during embryonic heart development. In the cardiovascular system, the beating of the heart is a dynamic and key regulatory process, which is functionally regulated by the coordinated spread of electrical activity through heart muscle cells. Heart tissues are composed of individual cells, each bearing specialized cell surface membrane structures called gap junctions that permit the intercellular exchange of ions and low molecular weight molecules. Gap junction channels are essential in normal heart function and they assist in the mediated spread of electrical impulses that stimulate synchronized contraction (via an electrical syncytium) of cardiac tissues. This present review describes the current knowledge of gap junction biology. In the first part, we summarise some relevant biochemical and physiological properties of gap junction proteins, including their structure and function. In the second part, we review the current evidence demonstrating the role of gap junction proteins in embryonic development with particular reference to those involved in embryonic heart development. Genetics and transgenic animal studies of gap junction protein function in embryonic heart development are considered and the alteration/disruption of gap junction intercellular communication which may lead to abnormal heart development is also discussed.

  1. Fast thermometry with a proximity Josephson junction

    Science.gov (United States)

    Wang, L. B.; Saira, O.-P.; Pekola, J. P.

    2018-01-01

    We couple a proximity Josephson junction to a Joule-heated normal metal film and measure its electron temperature under steady state and nonequilibrium conditions. With a timed sequence of heating and temperature probing pulses, we are able to monitor its electron temperature in nonequilibrium with effectively zero back-action from the temperature measurement in the form of additional dissipation or thermal conductance. The experiments demonstrate the possibility of using a fast proximity Josephson junction thermometer for studying thermal transport in mesoscopic systems and for calorimetry.

  2. Astroglial gap junctions shape neuronal network activity.

    Science.gov (United States)

    Pannasch, Ulrike; Derangeon, Mickael; Chever, Oana; Rouach, Nathalie

    2012-05-01

    Astrocytes, the third element of the tripartite synapse, are active players in neurotransmission. Up to now, their involvement in neuronal functions has primarily been investigated at the single cell level. However, a key property of astrocytes is that they communicate via extensive networks formed by gap junction channels. Recently, we have shown that this networking modulates the moment to moment basal synaptic transmission and plasticity via the regulation of extracellular potassium and glutamate levels. Here we show that astroglial gap junctional communication also regulates neuronal network activity. We discuss these findings and their implications for brain information processing.

  3. Clarifying the atrioventricular junctional anatomy in the setting of double outlet right atrium

    Science.gov (United States)

    Gupta, Saurabh Kumar; Gupta, Anunay; Ramakrishnan, Sivasubramanian; Anderson, Robert H

    2015-01-01

    Double outlet atrium is a rare cardiac anomaly wherein one of the atriums, most frequently the right atrium, opens into both the ventricles. Although seen more commonly in the setting of atrioventricular septal defect, this arrangement can also be found when one of the atrioventricular connections is atretic due to absence of the atrioventricular connection and the other atrioventricular valve straddles the muscular ventricular septum. It is the specific anatomy and connections of the atrioventricular junction that clarifies the situation and distinguishes between these two types of double outlet atrium. In this report, we present a case of double outlet right atrium co-existing with the absence of left atrioventricular connection. We then discuss the morphologic aspects of this interesting anomaly. PMID:26556972

  4. Relationship between Critical Current Fluctuation of Superconducting Bicrystal Junction and Junction Parameters

    Science.gov (United States)

    Enpuku, Keiji; Minotani, Tadashi; Shiraishi, Fumio; Kandori, Atushi

    1999-04-01

    Critical current fluctuation of bicrystal junctions is estimated from the 1/f flux noise of the superconducting quantum interference device (SQUID) at T=77 K. The relationships between the current fluctuation and junction parameters, such as critical current Io and resistance R, are obtained. The obtained parameter dependence can be well explained by using the parameter dependence of the resistance fluctuation reported by Marx and Gross [Appl. Phys. Lett. 70, 120 (1997)] and the relationship between Io and R obtained for the present junctions. The agreement indicates that the critical current fluctuation is correlated with the resistance fluctuation through the relationship between Io and R.

  5. Junction formation and current transport mechanisms in hybrid n-Si/PEDOT:PSS solar cells

    Science.gov (United States)

    Jäckle, Sara; Mattiza, Matthias; Liebhaber, Martin; Brönstrup, Gerald; Rommel, Mathias; Lips, Klaus; Christiansen, Silke

    2015-08-01

    We investigated hybrid inorganic-organic solar cells combining monocrystalline n-type silicon (n-Si) and a highly conductive polymer poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS). The build-in potential, photo- and dark saturation current at this hybrid interface are monitored for varying n-Si doping concentrations. We corroborate that a high build-in potential forms at the hybrid junction leading to strong inversion of the n-Si surface. By extracting work function and valence band edge of the polymer from ultraviolet photoelectron spectroscopy, a band diagram of the hybrid n-Si/PEDOT:PSS heterojunction is presented. The current-voltage characteristics were analyzed using Schottky and abrupt pn-junction models. The magnitude as well as the dependence of dark saturation current on n-Si doping concentration proves that the transport is governed by diffusion of minority charge carriers in the n-Si and not by thermionic emission of majorities over a Schottky barrier. This leads to a comprehensive explanation of the high observed open-circuit voltages of up to 634 mV connected to high conversion efficiency of almost 14%, even for simple planar device structures without antireflection coating or optimized contacts. The presented work clearly shows that PEDOT:PSS forms a hybrid heterojunction with n-Si behaving similar to a conventional pn-junction and not, like commonly assumed, a Schottky junction.

  6. Schottky junction photovoltaic devices based on CdS single nanobelts.

    Science.gov (United States)

    Ye, Y; Dai, L; Wu, P C; Liu, C; Sun, T; Ma, R M; Qin, G G

    2009-09-16

    Schottky junction photovoltaic (PV) devices were fabricated on single CdS nanobelts (NBs). Au was used as the Schottky contact, and In/Au was used as the ohmic contact to CdS NB. Typically, the Schottky junction exhibits a well-defined rectifying behavior in the dark with a rectification ratio greater than 10(3) at +/- 0.3 V; and the PV device exhibits a clear PV behavior with an open circuit photovoltage of about 0.16 V, a short circuit current of about 23.8 pA, a maximum output power of about 1.6 pW, and a fill factor of 42%. Moreover, the output power can be multiplied by connecting two or more of the Schottky junction PV devices, made on a single CdS NB, in parallel or in series. This study demonstrates that the 1D Schottky junction PV devices, which have the merits of low cost, easy fabrication and material universality, can be an important candidate for power sources in nano-optoelectronic systems.

  7. Ohmic contact junction of carbon nanotubes fabricated by in situ electron beam deposition

    International Nuclear Information System (INIS)

    Wang, Y G; Wang, T H; Lin, X W; Dravid, V P

    2006-01-01

    We present experimental evidence of in situ fabrication of multi-walled carbon nanotube junctions via electron beam induced deposition. The tip-to-tip interconnection of the nanotubes involves the alignment of two nanotubes via a piezodriven nanomanipulator and nano-welding by electron beam deposition. Hydrocarbon contamination from the pump oil vapour of the vacuum system of the TEM chamber was used as the solder; this is superior to the already available metallic solders because its composition is identical to the carbon nanotube. The hydrocarbon deposition, with perfect wettability, on the nanotubes establishes strong mechanical binding between the two nanotubes to form an integrated structure. Consequently, the nanotubes cross-linked by the hydrocarbon solder produce good electrical and mechanical connections. The joint dimension was determined by the size of the electron beam, which results in a sound junction with well-defined geometry and the smallest junction size obtained so far. In situ electric measurement showed a linear current-voltage property for the multi-walled nanotube junction

  8. Improving transition voltage spectroscopy of molecular junctions

    DEFF Research Database (Denmark)

    Markussen, Troels; Chen, Jingzhe; Thygesen, Kristian Sommer

    2011-01-01

    Transition voltage spectroscopy (TVS) is a promising spectroscopic tool for molecular junctions. The principles in TVS is to find the minimum on a Fowler-Nordheim plot where ln(I/V2) is plotted against 1/V and relate the voltage at the minimum Vmin to the closest molecular level. Importantly, Vmin...

  9. Intrinsically shunted Josephson junctions for electronics applications

    Science.gov (United States)

    Belogolovskii, M.; Zhitlukhina, E.; Lacquaniti, V.; De Leo, N.; Fretto, M.; Sosso, A.

    2017-07-01

    Conventional Josephson metal-insulator-metal devices are inherently underdamped and exhibit hysteretic current-voltage response due to a very high subgap resistance compared to that in the normal state. At the same time, overdamped junctions with single-valued characteristics are needed for most superconducting digital applications. The usual way to overcome the hysteretic behavior is to place an external low-resistance normal-metal shunt in parallel with each junction. Unfortunately, such solution results in a considerable complication of the circuitry design and introduces parasitic inductance through the junction. This paper provides a concise overview of some generic approaches that have been proposed in order to realize internal shunting in Josephson heterostructures with a barrier that itself contains the desired resistive component. The main attention is paid to self-shunted devices with local weak-link transmission probabilities that are so strongly disordered in the interface plane that transmission probabilities are tiny for the main part of the transition region between two super-conducting electrodes, while a small part of the interface is well transparent. We discuss the possibility of realizing a universal bimodal distribution function and emphasize advantages of such junctions that can be considered as a new class of self-shunted Josephson devices promising for practical applications in superconducting electronics operating at 4.2 K.

  10. Generalized Eck peak in inhomogeneous Josephson junctions

    Science.gov (United States)

    Fistul, Mikhail V.; Giuliani, Gabriele F.

    1997-02-01

    In inhomogeneous Josephson junctions the Eck peak characterizing the current-voltage characteristics is predicted to be replaced by a rather different yet prominent feature whose location and shape strongly depend on the strength of the applied magnetic field and the spatial correlations of the associated distorted Abrikosov flux lattice.

  11. Polyphosphonium-based ion bipolar junction transistors.

    Science.gov (United States)

    Gabrielsson, Erik O; Tybrandt, Klas; Berggren, Magnus

    2014-11-01

    Advancements in the field of electronics during the past few decades have inspired the use of transistors in a diversity of research fields, including biology and medicine. However, signals in living organisms are not only carried by electrons but also through fluxes of ions and biomolecules. Thus, in order to implement the transistor functionality to control biological signals, devices that can modulate currents of ions and biomolecules, i.e., ionic transistors and diodes, are needed. One successful approach for modulation of ionic currents is to use oppositely charged ion-selective membranes to form so called ion bipolar junction transistors (IBJTs). Unfortunately, overall IBJT device performance has been hindered due to the typical low mobility of ions, large geometries of the ion bipolar junction materials, and the possibility of electric field enhanced (EFE) water dissociation in the junction. Here, we introduce a novel polyphosphonium-based anion-selective material into npn-type IBJTs. The new material does not show EFE water dissociation and therefore allows for a reduction of junction length down to 2 μm, which significantly improves the switching performance of the ion transistor to 2 s. The presented improvement in speed as well the simplified design will be useful for future development of advanced iontronic circuits employing IBJTs, for example, addressable drug-delivery devices.

  12. Preoperative Chemoradiotherapy for Esophageal or Junctional Cancer

    NARCIS (Netherlands)

    van Hagen, P.; Hulshof, M. C. C. M.; van Lanschot, J. J. B.; Steyerberg, E. W.; van Berge Henegouwen, M. I.; Wijnhoven, B. P. L.; Richel, D. J.; Nieuwenhuijzen, G. A. P.; Hospers, G. A. P.; Bonenkamp, J. J.; Cuesta, M. A.; Blaisse, R. J. B.; Busch, O. R. C.; ten Kate, F. J. W.; Creemers, G.-J.; Punt, C. J. A.; Plukker, J. T. M.; Verheul, H. M. W.; Spillenaar Bilgen, E. J.; van Dekken, H.; van der Sangen, M. J. C.; Rozema, T.; Biermann, K.; Beukema, J. C.; Piet, A. H. M.; van Rij, C. M.; Reinders, J. G.; Tilanus, H. W.; van der Gaast, A.; Bergman, J. J. G. H. M.; Bartelsman, J. F.; Bissumbar, A.; Blom, R. L.; Geijsen, E. D.; van Heijl, M.; Obertop, H.; Koning, C. C. E.; Offerhaus, G. J.; Omloo, J. M.; Wilmink, H.; Aparicio Pages, M. N.; van den Nieuwenhof-Biesheuvel, L.; Eijkenboom, W. M. H.; Koppert, L. B.; Meijer, D. A.; Siersema, P. D.; Spaander, M. C. V.; Verheij, C.; Vollebregt, C.; van Krieken, J. H. J. M.; van Mansum, W.; van Dam, G.; van Dullemen, H. M.; Eerens, A.; van der Jagt, E.; Karnebeld, A.; Kluin, Ph; Mul, V. E. M.; Pruim, J.; Siemerink, E.; Weersma, R. K.; Fraikin, T.; Peters, C. W. A. H.

    2012-01-01

    BACKGROUND The role of neoadjuvant chemoradiotherapy in the treatment of patients with esophageal or esophagogastric-junction cancer is not well established. We compared chemoradiotherapy followed by surgery with surgery alone in this patient population. METHODS We randomly assigned patients with

  13. Maskless Arbitrary Writing of Molecular Tunnel Junctions.

    Science.gov (United States)

    Byeon, Seo Eun; Kim, Miso; Yoon, Hyo Jae

    2017-11-22

    Since fabricating geometrically well-defined, noninvasive, and compliant electrical contacts over molecular monolayers is difficult, creating molecular-scale electronic devices that function in high yield with good reproducibility is challenging. Moreover, none of the previously reported methods to form organic-electrode contacts at the nanometer and micrometer scales have resulted in directly addressable contacts in an untethered form under ambient conditions without the use of cumbersome equipment and nanolithography. Here we show that in situ encapsulation of a liquid metal (eutectic Ga-In alloy) microelectrode, which is used for junction formation, with a convenient photocurable polymeric scaffold enables untethering of the electrode and direct writing of arbitrary arrays of high-yielding molecular junctions under ambient conditions in a maskless fashion. The formed junctions function in quantitative yields and can afford tunneling currents with high reproducibility; they also function at low temperatures and under bent. The results reported here promise a massively parallel printing technology to construct integrated circuits based on molecular junctions with soft top contacts.

  14. Macroscopic Refrigeration Using Superconducting Tunnel Junctions

    Science.gov (United States)

    Lowell, Peter; O'Neil, Galen; Underwood, Jason; Zhang, Xiaohang; Ullom, Joel

    2014-03-01

    Sub-kelvin temperatures are often a prerequisite for modern scientific experiments, such as quantum information processing, astrophysical missions looking for dark energy signatures and tabletop time resolved x-ray spectroscopy. Existing methods of reaching these temperatures, such as dilution refrigerators, are bulky and costly. In order to increase the accessibility of sub-Kelvin temperatures, we have developed a new method of refrigeration using normal-metal/insulator/superconductor (NIS) tunnel junctions. NIS junctions cool the electrons in the normal metal since the hottest electrons selectively tunnel from the normal metal into the superconductor. By extending the normal metal onto a thermally isolated membrane, the cold electrons can cool the phonons through the electron-phonon coupling. When these junctions are combined with a pumped 3He system, they provide a potentially inexpensive method of reaching these temperatures. Using only three devices, each with a junction area of approximately 3,500 μm2, we have cooled a 2 cm3 Cu plate from 290 mK to 256 mK. We will present these experimental results along with recent modeling predictions that strongly suggest that further refinements will allow cooling from 300 mK to 120 mK. This work is supported by the NASA APRA program.

  15. Anatomy of the human atrioventricular junctions revisited

    NARCIS (Netherlands)

    Anderson, R. H.; Ho, S. Y.; Becker, A. E.

    2000-01-01

    There have been suggestions made recently that our understanding of the atrioventricular junctions of the heart is less than adequate, with claims for several new findings concerning the arrangement of the ordinary working myocardium and the specialised pathways for atrioventricular conduction. In

  16. impairs gap junction function causing congenital cataract

    Indian Academy of Sciences (India)

    Navya

    2017-03-24

    Mar 24, 2017 ... Connexin 46 (Cx46) is important for gap junction channels formation which plays crucial role in the preservation of lens homeostasis and transparency. Previously, we have identified a missense mutation. (p.V44M) of Cx46 in a congenital cataract family. This study aims at dissecting the potential.

  17. Two-dimensional bipolar junction transistors

    Science.gov (United States)

    Gharekhanlou, Behnaz; Khorasani, Sina; Sarvari, Reza

    2014-03-01

    Recent development in fabrication technology of planar two-dimensional (2D) materials has introduced the possibility of numerous novel applications. Our recent analysis has revealed that by definition of p-n junctions through appropriate patterned doping of 2D semiconductors, ideal exponential I-V characteristics may be expected. However, the theory of 2D junctions turns out to be very different to that of standard bulk junctions. Based on this theory of 2D diodes, we construct for the first time a model to describe 2D bipolar junction transistors (2D-BJTs). We derive the small-signal equivalent model, and estimate the performance of a 2D-BJT device based on graphone as the example material. A current gain of about 138 and maximum threshold frequency of 77 GHz, together with a power-delay product of only 4 fJ per 1 μm lateral width is expected at an operating voltage of 5 V. In addition, we derive the necessary formulae and a new approximate solution for the continuity equation in the 2D configuration, which have been verified against numerical solutions.

  18. Craniocervical junction abnormalities with atlantoaxial subluxation ...

    African Journals Online (AJOL)

    Craniocervical junction abnormalities with atlantoaxial subluxation caused by ventral subluxation of C2 were diagnosed in a 6-month-old female Pomeranian with tetraplegia as a clinical sign. Lateral survey radiography of the neck with flexion revealed atlantoaxial subluxation with ventral subluxation of C2. Computed ...

  19. Post-Junctional Modulatory Effects of Hemicholinium on Isolated ...

    African Journals Online (AJOL)

    Conclusion: HC-3 has antimuscarinic actions on Ach- and carbacholinduced responses; a post-junctional action at the neuromuscular junction and differing anticholinesterase activities with DFP and physostigmine but not edrophonium. KEY WORDS: Post-Junctional, Anti-Muscarinic, Anti-Cholinesterase Jnl of Medical ...

  20. Phenomenological approach to bistable behavior of Josephson junctions

    International Nuclear Information System (INIS)

    Nishi, K.; Nara, S.; Hamanaka, K.

    1985-01-01

    The interaction of unbiased Josephson junction with external electromagnetic field in the presence of externally applied uniform magnetic field is theoretically examined by means of phenomenological treatment. It is proposed that an irradiated junction with suitably chosen parameters shows a bistable behavior of voltage across the junction as a function of the radiation intensity

  1. Attribute-space connectivity and connected filters

    NARCIS (Netherlands)

    Wilkinson, Michael H.F.

    2007-01-01

    In this paper connected operators from mathematical morphology are extended to a wider class of operators, which are based on connectivities in higher dimensional spaces, similar to scale spaces, which will be called attribute-spaces. Though some properties of connected filters are lost,

  2. The anatomical locus of T-junction processing.

    Science.gov (United States)

    Schirillo, James A

    2009-07-01

    Inhomogeneous surrounds can produce either asymmetrical or symmetrical increment/decrement induction by orienting T-junctions to selectively group a test patch with surrounding regions [Melfi, T., & Schirillo, J. (2000). T-junctions in inhomogeneous surrounds. Vision Research, 40, 3735-3741]. The current experiments aimed to determine where T-junctions are processed by presenting each eye with a different image so that T-junctions exist only in the fused percept. Only minor differences were found between retinal and cortical versus cortical-only conditions, indicating that T-junctions are processed cortically.

  3. Planar Josephson tunnel junctions in a transverse magnetic field

    DEFF Research Database (Denmark)

    Monacoa, R.; Aarøe, Morten; Mygind, Jesper

    2007-01-01

    Traditionally, since the discovery of the Josephson effect in 1962, the magnetic diffraction pattern of planar Josephson tunnel junctions has been recorded with the field applied in the plane of the junction. Here we discuss the static junction properties in a transverse magnetic field where...... demagnetization effects imposed by the tunnel barrier and electrodes geometry are important. Measurements of the junction critical current versus magnetic field in planar Nb-based high-quality junctions with different geometry, size, and critical current density show that it is advantageous to use a transverse...... magnetic field rather than an in-plane field. The conditions under which this occurs are discussed....

  4. Intermodal Passenger Connectivity Database -

    Data.gov (United States)

    Department of Transportation — The Intermodal Passenger Connectivity Database (IPCD) is a nationwide data table of passenger transportation terminals, with data on the availability of connections...

  5. Output voltage calculations in double barrier magnetic tunnel junctions with asymmetric voltage behavior

    KAUST Repository

    Useinov, Arthur

    2011-10-22

    In this paper we study the asymmetric voltage behavior (AVB) of the tunnel magnetoresistance (TMR) for single and double barrier magnetic tunnel junctions (MTJs) in range of a quasi-classical free electron model. Numerical calculations of the TMR-V curves, output voltages and I-V characteristics for negative and positive values of applied voltages were carried out using MTJs with CoFeB/MgO interfaces as an example. Asymmetry of the experimental TMR-V curves is explained by different values of the minority and majority Fermi wave vectors for the left and right sides of the tunnel barrier, which arises due to different annealing regimes. Electron tunneling in DMTJs was simulated in two ways: (i) Coherent tunneling, where the DMTJ is modeled as one tunnel system and (ii) consecutive tunneling, where the DMTJ is modeled by two single barrier junctions connected in series. © 2012 Elsevier B.V. All rights reserved.

  6. Asymmetric voltage behavior of the tunnel magnetoresistance in double barrier magnetic tunnel junctions

    KAUST Repository

    Useinov, Arthur

    2012-06-01

    In this paper, we study the value of the tunnel magnetoresistance (TMR) as a function of the applied voltage in double barrier magnetic tunnel junctions (DMTJs) with the left and right ferromagnetic (FM) layers being pinned and numerically estimate the possible difference of the TMR curves for negative and positive voltages in the homojunctions (equal barriers and electrodes). DMTJs are modeled as two single barrier junctions connected in series with consecutive tunneling (CST). We investigated the asymmetric voltage behavior of the TMR for the CST in the range of a general theoretical model. Significant asymmetries of the experimental curves, which arise due to different annealing regimes, are mostly explained by different heights of the tunnel barriers and asymmetries of spin polarizations in magnetic layers. © (2012) Trans Tech Publications.

  7. Tight junction between endothelial cells: the interaction between nanoparticles and blood vessels

    Directory of Open Access Journals (Sweden)

    Yue Zhang

    2016-05-01

    Full Text Available Since nanoparticles are now widely applied as food additives, in cosmetics and other industries, especially in medical therapy and diagnosis, we ask here whether nanoparticles can cause several adverse effects to human health. In this review, based on research on nanotoxicity, we mainly discuss the negative influence of nanoparticles on blood vessels in several aspects and the potential mechanism for nanoparticles to penetrate endothelial layers of blood vessels, which are the sites of phosphorylation of tight junction proteins (claudins, occludins, and ZO (Zonula occludens proteins, oxidative stress and shear stress. We propose a connection between the presence of nanoparticles and the regulation of the tight junction, which might be the key approach for nanoparticles to penetrate endothelial layers and then have an impact on other tissues and organs.

  8. Non-Lagrangian theories from brane junctions

    International Nuclear Information System (INIS)

    Bao, Ling; Mitev, Vladimir

    2013-10-01

    In this article we use 5-brane junctions to study the 5D T N SCFTs corresponding to the 5D N=1 uplift of the 4D N=2 strongly coupled gauge theories, which are obtained by compactifying N M5 branes on a sphere with three full punctures. Even though these theories have no Lagrangian description, by using the 5-brane junctions proposed by Benini, Benvenuti and Tachikawa, we are able to derive their Seiberg-Witten curves and Nekrasov partition functions. We cross-check our results with the 5D superconformal index proposed by Kim, Kim and Lee. Through the AGTW correspondence, we discuss the relations between 5D superconformal indices and n-point functions of the q-deformed W N Toda theories.

  9. Non-Lagrangian theories from brane junctions

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Ling [Chalmers Univ. of Technology, Goeteborg (Sweden); Mitev, Vladimir [Humboldt Univ., Berlin (Germany). Inst. fuer Mathematik und Inst. fuer Physik; Pomoni, Elli [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany). Theory Group; Taki, Masato [RIKEN Nishina Center, Saitama (Japan). Mathematical Physics Lab.; Yagi, Futoshi [International School of Advanced Studies (SISSA), Trieste (Italy); INFN, Trieste (Italy); Korea Institute for Advanced Study (KIAS), Seoul (Korea, Republic of)

    2013-10-15

    In this article we use 5-brane junctions to study the 5D T{sub N} SCFTs corresponding to the 5D N=1 uplift of the 4D N=2 strongly coupled gauge theories, which are obtained by compactifying N M5 branes on a sphere with three full punctures. Even though these theories have no Lagrangian description, by using the 5-brane junctions proposed by Benini, Benvenuti and Tachikawa, we are able to derive their Seiberg-Witten curves and Nekrasov partition functions. We cross-check our results with the 5D superconformal index proposed by Kim, Kim and Lee. Through the AGTW correspondence, we discuss the relations between 5D superconformal indices and n-point functions of the q-deformed W{sub N} Toda theories.

  10. Electron transport in doped fullerene molecular junctions

    Science.gov (United States)

    Kaur, Milanpreet; Sawhney, Ravinder Singh; Engles, Derick

    The effect of doping on the electron transport of molecular junctions is analyzed in this paper. The doped fullerene molecules are stringed to two semi-infinite gold electrodes and analyzed at equilibrium and nonequilibrium conditions of these device configurations. The contemplation is done using nonequilibrium Green’s function (NEGF)-density functional theory (DFT) to evaluate its density of states (DOS), transmission coefficient, molecular orbitals, electron density, charge transfer, current, and conductance. We conclude from the elucidated results that Au-C16Li4-Au and Au-C16Ne4-Au devices behave as an ordinary p-n junction diode and a Zener diode, respectively. Moreover, these doped fullerene molecules do not lose their metallic nature when sandwiched between the pair of gold electrodes.

  11. Junction conditions in extended Teleparallel gravities

    Energy Technology Data Exchange (ETDEWEB)

    De la Cruz-Dombriz, Álvaro [Departamento de Física Teórica I, Ciudad Universitaria, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Dunsby, Peter K.S.; Sáez-Gómez, Diego, E-mail: dombriz@fis.ucm.es, E-mail: peter.dunsby@uct.ac.za, E-mail: diego.saezgomez@uct.ac.za [Astrophysics, Cosmology and Gravity Centre (ACGC), Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, Cape Town (South Africa)

    2014-12-01

    In the context of extended Teleparallel gravity theories, we address the issue of junction conditions required to guarantee the correct matching of different regions of spacetime. In the absence of shells/branes, these conditions turn out to be more restrictive than their counterparts in General Relativity as in other extended theories of gravity. In fact, the general junction conditions on the matching hypersurfaces depend on the underlying theory and a new condition on the induced tetrads in order to avoid delta-like distributions in the field equations. This result imposes strict consequences on the viability of standard solutions such as the Einstein-Straus-like construction. We find that the continuity of the scalar torsion is required in order to recover the usual General Relativity results.

  12. Magnetoamplification in a bipolar magnetic junction transistor.

    Science.gov (United States)

    Rangaraju, N; Peters, J A; Wessels, B W

    2010-09-10

    We have demonstrated the first bipolar magnetic junction transistor using a dilute magnetic semiconductor. For an InMnAs p-n-p transistor magnetoamplification is observed at room temperature. The observed magnetoamplification is attributed to the magnetoresistance of the magnetic semiconductor InMnAs heterojunction. The magnetic field dependence of the transistor characteristics confirm that the magnetoamplification results from the junction magnetoresistance. To describe the experimentally observed transistor characteristics, we propose a modified Ebers-Moll model that includes a series magnetoresistance attributed to spin-selective conduction. The capability of magnetic field control of the amplification in an all-semiconductor transistor at room temperature potentially enables the creation of new computer logic architecture where the spin of the carriers is utilized.

  13. Excess junction current of silicon solar cells

    Science.gov (United States)

    Wang, E. Y.; Legge, R. N.; Christidis, N.

    1973-01-01

    The current-voltage characteristics of n(plus)-p silicon solar cells with 0.1, 1.0, 2.0, and 10 ohm-cm p-type base materials have been examined in detail. In addition to the usual I-V measurements, we have studied the temperature dependence of the slope of the I-V curve at the origin by the lock-in technique. The excess junction current coefficient (Iq) deduced from the slope at the origin depends on the square root of the intrinsic carrier concentration. The Iq obtained from the I-V curve fitting over the entire forward bias region at various temperatures shows the same temperature dependence. This result, in addition to the presence of an aging effect, suggest that the surface channel effect is the dominant cause of the excess junction current.

  14. Characterization of magnetic tunnel junction test pads

    DEFF Research Database (Denmark)

    Østerberg, Frederik Westergaard; Kjær, Daniel; Nielsen, Peter Folmer

    2015-01-01

    relies on four-point probe measurements performed with a range of different probe pitches and was originally developed for infinite samples. Using the method of images, we derive a modified CIPT model, which compensates for the insulating boundaries of a finite rectangular sample geometry. We measure...... as a function of position on a square tunnel junction pad are used to investigate the sensitivity of the measurement results to probe misalignment....... on square tunnel junction pads with varying sizes and analyze the measured data using both the original and the modified CIPT model. Thus, we determine in which sample size range the modified CIPT model is needed to ensure validity of the extracted sample parameters, RA and TMR. In addition, measurements...

  15. Dissipation and traversal time in Josephson junctions

    International Nuclear Information System (INIS)

    Cacciari, Ilaria; Ranfagni, Anedio; Moretti, Paolo

    2010-01-01

    The various ways of evaluating dissipative effects in macroscopic quantum tunneling are re-examined. The results obtained by using functional integration, while confirming those of previously given treatments, enable a comparison with available experimental results relative to Josephson junctions. A criterion based on the shortening of the semiclassical traversal time τ of the barrier with regard to dissipation can be established, according to which Δτ/τ > or approx. N/Q, where Q is the quality factor of the junction and N is a numerical constant of order unity. The best agreement with the experiments is obtained for N=1.11, as it results from a semiempirical analysis based on an increase in the potential barrier caused by dissipative effects.

  16. Shot noise in YBCO bicrystal Josephson junctions

    DEFF Research Database (Denmark)

    Constantinian, K.Y.; Ovsyannikov, G.A.; Borisenko, I.V.

    2003-01-01

    We measured spectral noise density in YBCO symmetric bicrystal Josephson junctions on sapphire substrates at bias voltages up to 100 mV and T 4.2 K. Normal state resistance of the Josephson junctions, R-N = 20-90 Omega and ICRN up to 2.2 mV have been observed in the experimental samples. Noise...... measurements were carried out within frequency bands of 1-2 GHz and 0.3-300 kHz. At bias voltages 10 less than or equal to V less than or equal to 60 mV a linear voltage dependence of noise power has been registered, while at V less than or equal to 5 mV a noticeable noise rise has been observed. The latter...

  17. Charge Transport Phenomena in Peptide Molecular Junctions

    Directory of Open Access Journals (Sweden)

    Alessandra Luchini

    2008-01-01

    Full Text Available Inelastic electron tunneling spectroscopy (IETS is a valuable in situ spectroscopic analysis technique that provides a direct portrait of the electron transport properties of a molecular species. In the past, IETS has been applied to small molecules. Using self-assembled nanoelectronic junctions, IETS was performed for the first time on a large polypeptide protein peptide in the phosphorylated and native form, yielding interpretable spectra. A reproducible 10-fold shift of the I/V characteristics of the peptide was observed upon phosphorylation. Phosphorylation can be utilized as a site-specific modification to alter peptide structure and thereby influence electron transport in peptide molecular junctions. It is envisioned that kinases and phosphatases may be used to create tunable systems for molecular electronics applications, such as biosensors and memory devices.

  18. Minimum cost connection networks

    DEFF Research Database (Denmark)

    Hougaard, Jens Leth; Tvede, Mich

    In the present paper we consider the allocation of cost in connection networks. Agents have connection demands in form of pairs of locations they want to be connected. Connections between locations are costly to build. The problem is to allocate costs of networks satisfying all connection demands....... We use three axioms to characterize allocation rules that truthfully implement cost minimizing networks satisfying all connection demands in a game where: (1) a central planner announces an allocation rule and a cost estimation rule; (2) every agent reports her own connection demand as well as all...... connection costs; and, (3) the central planner selects a cost minimizing network satisfying reported connection demands based on estimated connection costs and allocates true connection costs of the selected network....

  19. Nonlinearity in superconductivity and Josephson junctions

    International Nuclear Information System (INIS)

    Lazarides, N.

    1995-01-01

    Within the framework of the Bardeen, Cooper and Schrieffers (BCS) theory, the influence of anisotropy on superconducting states are investigated. Crystal anisotropy exists in un-conventional low temperature superconductors as e.g. U 1-x Th x Be 13 and in high temperature superconductors. Starting from a phenomenological pairing interaction of the electrons or holes, the BCS approach is used to derive a set of coupled nonlinear algebraic equations for the momentum dependent gap parameter. The emphasis is put on bifurcation phenomena between s-, d-wave and mixed s- and d-wave symmetry and the influence on measurable quantities as the electron specific heat, spin susceptibility and Josephson tunnelling. Pitch-fork and perturbed pitch-fork bifurcations have been found separating s- and d-wave superconducting states from mixed s- and d-wave states. The additional superconducting states give rise to jumps in the electron specific heat below the transition temperature. These jumps are rounded in the case of perturbed pitch-fork bifurcations. An experiment to measure the sign of the interlayer interaction using dc SQUIDS is suggested. The Ambegaokar-Baratoff formalism has been used for calculating the quasiparticle current and the two phase coherent tunnelling currents in a Josephson junction made of anisotropic superconductors. It is shown that anisotropy can lead to a reduction in the product of the normal resistance and the critical current. For low voltages across the junction the usual resistively shunted Josephson model can be used. Finally, bunching in long circular Josephson junctions and suppression of chaos in point junctions have been investigated. (au) 113 refs

  20. Internal dynamics of long Josephson junction oscillators

    DEFF Research Database (Denmark)

    Christiansen, Peter Leth; Lomdahl, P. S.; Scott, Alwyn C.

    1981-01-01

    Numerical computations on a sine-Gordon model of the Josephson junction fluxon oscillator are compared with experimental measurements. Good agreement is found for the voltage current characteristic, oscillator power output, and range of current bias over which oscillation is observed. Our numeric...... results imply a ''bunched-fluxon'' mode of oscillation at larger values of bias current. Applied Physics Letters is copyrighted by The American Institute of Physics....

  1. An epitaxial ferroelectric tunnel junction on silicon.

    Science.gov (United States)

    Li, Zhipeng; Guo, Xiao; Lu, Hui-Bin; Zhang, Zaoli; Song, Dongsheng; Cheng, Shaobo; Bosman, Michel; Zhu, Jing; Dong, Zhili; Zhu, Weiguang

    2014-11-12

    Epitaxially grown functional perovskites on silicon (001) and the ferroelectricity of a 3.2 nm thick BaTiO3 barrier layer are demonstrated. The polarization-switching-induced change in tunneling resistance is measured to be two orders of magnitude. The obtained results suggest the possibility of integrating ferroelectric tunnel junctions as binary data storage media in non-volatile memory cells on a silicon platform. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Josephson spin current in triplet superconductor junctions

    OpenAIRE

    Asano, Yasuhiro

    2006-01-01

    This paper theoretically discusses the spin current in spin-triplet superconductor / insulator / spin-triplet superconductor junctions. At low temperatures, a midgap Andreev resonant state anomalously enhances not only the charge current but also the spin current. The coupling between the Cooper pairs and the electromagnetic fields leads to the Frounhofer pattern in the direct current spin flow in magnetic fields and the alternative spin current under applied bias-voltages.

  3. Defect formation in long Josephson junctions

    DEFF Research Database (Denmark)

    Gordeeva, Anna; Pankratov, Andrey

    2010-01-01

    We study numerically a mechanism of vortex formation in a long Josephson junction within the framework of the one-dimensional sine-Gordon model. This mechanism is switched on below the critical temperature. It is shown that the number of fluxons versus velocity of cooling roughly scales according...... to the power law with the exponent of either 0.25 or 0.5 depending on the temperature variation in the critical current density....

  4. Development of Thin-Junction Detector

    Science.gov (United States)

    Chen, W.; Carini, G.; Keister, J.; Li, Z.; Rehak, P.

    2007-10-01

    Two methods to produce a thin-junction sensor are reported here. The first method consists of a regular boron implantation with energies of 2 keV (dose of 1 times 1015/cm2) and 5 keV (dose of 1 times 1014/cm2) into silicon directly, and 10 keV (1 X 1014/cm2), 45 keV (1 times 1015/cm2) into Si through a thin oxide layer (500 A and 1000 A respectively) to form a junction. An aluminum layer was coated in the same vacuum system after back-sputtering to remove oxide on top of the implanted silicon substrate. This method may have the following advantages: 1) it may improve the soft X-ray radiation hardness of the device because there is no oxide layer on the junction; 2) it substantially attenuates the incident visible light; and 3) it allows detection of low energy X-ray down to 300 eV. The second method consists of a low energy of 2 keV and dose of 1 times 1015/cm2 boron implantation into the bare silicon followed by laser annealing that activates boron with minimal diffusion, to retain the ultra thin-junction. The laser annealing method was compared with control wafers. Two of the control wafers were implanted by boron with the same energy and dose as that of the laser annealed wafer. One of them was annealed using high temperature of 1000degC and time of 30 minutes thermal annealing. The other was annealed using our regular annealing temperature of 700degC and with longer annealing time of 17 hours. The remaining control wafer was implanted by boron with higher energy of 45 keV and dose of 1 times 1015/cm2 (our standard boron implantation energy and dose) and annealed using regular (700degC, 30 min) thermal annealing.

  5. RADIOLOGICAL EVALUATION OF CRANIOVERTEBRAL JUNCTION ANOMALIES

    Directory of Open Access Journals (Sweden)

    Joji Reddy

    2015-08-01

    Full Text Available INTRODUCTION: Detailed discussions of the CVJ are conspicuously absent in many standard textbooks and chapters addressing the skull or cervical spine, since it lies in between these regions . CVJ anomalies are common in India subcontinent. OBJECTIVES : To outline the normal anatomy and various abnormalities of craniovertebral junction. To evaluate the most common developmental and acquired craniovertebral junction abnormalities . CRANIOMETRY AND DIAGNOSIS: Radiological evaluation of CVJ requir es identification of only a few anatomic structures. Over the years multiple lines , planes and angles have been described for assessment of CVJ relationship , initially with radiography and later with polytomography. Two lines have remained particularly use ful for evaluation of CVJ relationship with virtually any imaging modality: the chamberlain`s line and weckenheim ’ s clivus base line . Two angles also continue to be useful: the welcher basal angle and atlanto occipital joint axis angle. PATIENTS AND METHOD S: The prospective study of craniovertebral junction anomalies was carried out at Kurnool medical college , Governament general hospital Kurnool from NOV 2012 to AUG 2014. The patients are subjected to clinical evaluation and radiological evaluation. OBSERV ATIONS AND RESULTS : In our study there is male predominance with male to female ratio of 2:1 . Majority of patients are in the age group of 11 - 40 (73.26%. The commonest symptom seen is weakness of extremities ( 70% with associated numbness (50%. On clinica l examination pyramidal tract involvement noticed in 70% of cases. Basilar invagination is the most common followed by Atlantoocoipital assimilation (40% and AAD (30% . CONCLUSION : Computed tomography and magnetic resonance imaging are invalvable adjuncts to the plain radiographs in the evaluation of the craniovertebral junction anomalies. Chamberlain’s line and McGregor line are the most commonly applied craniometric measurements

  6. Decreased Vision and Junctional Scotoma from Pituicytoma

    Directory of Open Access Journals (Sweden)

    Nancy Huynh

    2012-05-01

    Full Text Available Pituicytomas are rare neoplasms of the sellar region. We report a case of vision loss and a junctional scotoma in a 43-year-old woman caused by compression of the optic chiasm by a pituitary tumor. The morphological and immunohistochemical characteristics of the tumor were consistent with the diagnosis of pituicytoma. The tumor was debulked surgically, and the patient’s vision improved.

  7. Magnetic remanence of Josephson junction arrays

    OpenAIRE

    Passos, W. A. C.; Araujo-Moreira, F. M.; Ortiz, W. A.

    1999-01-01

    In this work we study the magnetic remanence exhibited by Josephson junction arrays in response to an excitation with an AC magnetic field. The effect, predicted by numerical simulations to occur in a range of temperatures, is clearly seen in our tridimensional disordered arrays. We also discuss the influence of the critical current distribution on the temperature interval within which the array develops a magnetic remanence. This effect can be used to determine the critical current distribut...

  8. Electrical transport through a metal-molecule-metal junction; Transport electrique a travers une jonction metal-molecule-metal

    Energy Technology Data Exchange (ETDEWEB)

    Kergueris, Ch

    1998-12-17

    We investigate the electrical transport through a very few molecules connected to metallic electrodes at room temperature. First, the state of the art in molecular electronics is outlined. We present the most convincing molecular devices reported so far in the literature and the theoretical tools available to analyze the electron transport mechanism through a molecular junction. Second, we describe the use of mechanically controllable break junctions to investigate the electron transport properties through a metal-molecule-metal junction. Two kindsof molecules were adsorbed on the two facing gold electrodes, dodecane-thiol (DT) and bis-thiol-ter-thiophene ({alpha},{omega} T3), that are basically expected to behave as an insulator and as a molecular wire, respectively. In the latter case, we study the chemical reactivity of the molecule and show that {alpha},{omega} T3 is chemically adsorbed on gold electrodes. Current-voltage characteristics of the junction were observed at room temperature. The Gold-DT-Gold junction behaves as a simple metal-insulator-metal junction. On the other hand, the electron transport through a Gold-{alpha},{omega} T3-Gold junction explicitly involves the electronic structure of the molecule which gives rise to step-like features in the current-voltage characteristics. The measured zero bias conductance is interpreted using the scattering theory. At high bias, we discuss two different models: a coherent model where the electron has no time to be completely re-localized in the molecule and a sequential model where the electron is localized in the molecule during the transfer. Finally, we show that the mechanical action of decreasing the inter-electrodes spacing can be used to induce a strong modification of the current-voltage characteristics. (author)

  9. Highly Charged Ion (HCI) Modified Tunnel Junctions

    International Nuclear Information System (INIS)

    Pomeroy, J. M.; Grube, H.

    2009-01-01

    The neutralization energy carried by highly charged ions (HCIs) provides an alternative method for localizing energy on a target's surface, producing features and modifying surfaces with fluences and kinetic energy damage that are negligible compared to singly ionized atoms. Since each HCI can deposit an enormous amount of energy into a small volume of the surface (e.g., Xe 44+ delivers 51 keV of neutralization energy per HCI), each individual HCI's interaction with the target can produce a nanoscale feature. Many studies of HCI-surface features have characterized some basic principles of this unique ion-surface interaction, but the activity reported here has been focused on studying ensembles of HCI features in ultra-thin insulating films by fabricating multi-layer tunnel junction devices. The ultra-thin insulating barriers allow current to flow by tunneling, providing a very sensitive means of detecting changes in the barrier due to highly charged ion irradiation and, conversely, HCI modification provides a method of finely tuning the transparency of the tunnel junctions that spans several orders of magnitude for devices produced from a single process recipe. Systematic variation of junction bias, temperature, magnetic field and other parameters provides determination of the transport mechanism, defect densities, and magnetic properties of these nano-features and this novel approach to device fabrication.

  10. Superconducting junctions and method of making same

    International Nuclear Information System (INIS)

    Kapituinik, A.

    1993-01-01

    A method of making Josephson junctions in high critical temperature superconductors is described comprising the consecutive steps of: first forming a layer of high Tc copper oxide superconductor on a substrate by forming the constituent components of the superconductor onto the substrate so as to epitaxially grow the superconductor on the substrate with copper-oxygen planes parallel to the surface of the substrate, said layer formed in a pattern to create a desired electronic circuit; then narrowing selected portions of the superconductor circuit at locations where Josephson junctions are desired; then creating weak link areas at said selected portions by moving an electrode across the surface of said selected portions, generally from one side of the selected portion to the other side of the selected portion, at a distance from the surface suitable to maintain a tunnel current between the electrode and the selected portion and maintaining said tunnel current directly into said junction locations while the electrode is proximate to the selected portions and sustaining said tunnel current through the electrodes long enough to physically remove superconducting material from the selected portion; and then depositing a noble metal in the selected portion by evaporating an electrode made from the noble metal

  11. Anatomy of the junction of the inferior petrosal sinus and the internal jugular vein. Evaluation with MR imaging

    International Nuclear Information System (INIS)

    Takahashi, Satoshi; Tomura, Noriaki; Kato, Koki; Hirano, Yosinori; Izumi, Jun-ichi; Watarai, Jiro

    2000-01-01

    To evaluate the anatomy of the junction of the inferior petrosal sinus (IPS) and the internal jugular vein (IJV), magnetic resonance (MR) images of the jugular bulbs in 50 patients (age range, 15 to 83 years; mean age, 59.6 years) were retrospectively reviewed. Both MR imaging and intra-arterial digital subtraction angiography (IADSA) were performed in the 50 patients, and IPS venography was performed in 7 patients. Multiplanar reconstruction of the MR images was obtained using three-dimensional fast spoiled gradient-recalled acquisition in the steady state (3-D fast SPGR) with gadopentate dimegulmin (Gd-DTPA). IPS and other venous structures were identified around the jugular bulbs both on the MR images and by IPS venography. The diameters of the junctions of the IPS and IJV were measured on the MR images. IN 97 side (97%) of the 50 patients, a petrosal confluence was found on the medial side of the jugular bulb, connecting with the anterior condylar vein, inferior petroclival vein, basilar plexus and the IPS. Extracranial extension of the IPS was seen on 3 sides of 3 patients (right: 1, left: 2) (3%). All 3 patients showed the IPS connecting with the internal jugular vein below the anterior condylar vein. The minimum diameter of IPS-IJV junction was 1 mm or greater in all cases. In conclusion, the junction of the IPS and the IJV is easily identified by contrast-enhanced 3-D fast SPGR sequences, which is helpful for IPS catheterization in endovascular treatment. (author)

  12. RELAP-7 Progress Report: A Mathematical Model for 1-D Compressible, Single-Phase Flow Through a Branching Junction

    Energy Technology Data Exchange (ETDEWEB)

    Berry, R. A. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2017-08-14

    In the literature, the abundance of pipe network junction models, as well as inclusion of dissipative losses between connected pipes with loss coefficients, has been treated using the incompressible flow assumption of constant density. This approach is fundamentally, physically wrong for compressible flow with density change. This report introduces a mathematical modeling approach for general junctions in piping network systems for which the transient flows are compressible and single-phase. The junction could be as simple as a 1-pipe input and 1-pipe output with differing pipe cross-sectional areas for which a dissipative loss is necessary, or it could include an active component, between an inlet pipe and an outlet pipe, such as a pump or turbine. In this report, discussion will be limited to the former. A more general branching junction connecting an arbitrary number of pipes with transient, 1-D compressible single-phase flows is also presented. These models will be developed in a manner consistent with the use of a general equation of state like, for example, the recent Spline-Based Table Look-up method [1] for incorporating the IAPWS-95 formulation [2] to give accurate and efficient calculations for properties for water and steam with RELAP-7 [3].

  13. Minimum cost connection networks

    DEFF Research Database (Denmark)

    Hougaard, Jens Leth; Tvede, Mich

    2015-01-01

    In the present paper we consider the allocation of costs in connection networks. Agents have connection demands in form of pairs of locations they want to have connected. Connections between locations are costly to build. The problem is to allocate costs of networks satisfying all connection...... demands. We use a few axioms to characterize allocation rules that truthfully implement cost minimizing networks satisfying all connection demands in a game where: (1) a central planner announces an allocation rule and a cost estimation rule; (2) every agent reports her own connection demand as well...... as all connection costs; (3) the central planner selects a cost minimizing network satisfying reported connection demands based on the estimated costs; and, (4) the planner allocates the true costs of the selected network. It turns out that an allocation rule satisfies the axioms if and only if relative...

  14. Coulomb blockade in turnstile with multiple tunnel junctions

    CERN Document Server

    Lee, S C; Kang, D S; Kim, D C; Choi, C K; Ryu, J Y

    1999-01-01

    On the basis of the analytic solutions to the electrostatic problem of the multi-grated-small-junction systems, the stable domain for the Coulomb blockade of turnstile with multiple tunnel junctions at zero temperature has been analyzed as a function of the number of tunnel junction, the ratio of the gate capacitance to the junction capacitance, and the asymmetric factor. Our results show that domains form various shaped regions according to the asymmetric factor and their size depends on the number of junction and the ratio of the gate capacitance to the junction capacitance. In particular, it is shown that electrons can be transferred in positive and/or negative bias voltage depending on the asymmetric factor when an appropriate gate cycle is applied. Thus, the asymmetric factor plays an important role in determining the turnstile operation.

  15. Single P-N junction tandem photovoltaic device

    Science.gov (United States)

    Walukiewicz, Wladyslaw [Kensington, CA; Ager, III, Joel W.; Yu, Kin Man [Lafayette, CA

    2011-10-18

    A single P-N junction solar cell is provided having two depletion regions for charge separation while allowing the electrons and holes to recombine such that the voltages associated with both depletion regions of the solar cell will add together. The single p-n junction solar cell includes an alloy of either InGaN or InAlN formed on one side of the P-N junction with Si formed on the other side in order to produce characteristics of a two junction (2J) tandem solar cell through only a single P-N junction. A single P-N junction solar cell having tandem solar cell characteristics will achieve power conversion efficiencies exceeding 30%.

  16. Quantum interference in thermoelectric molecular junctions: A toy model perspective

    Science.gov (United States)

    Nozaki, Daijiro; Avdoshenko, Stas M.; Sevinçli, Hâldun; Cuniberti, Gianaurelio

    2014-08-01

    Quantum interference (QI) phenomena between electronic states in molecular circuits offer a new opportunity to design new types of molecular devices such as molecular sensors, interferometers, and thermoelectric devices. Controlling the QI effect is a key challenge for such applications. For the development of single molecular devices employing QI effects, a systematic study of the relationship between electronic structure and the quantum interference is needed. In order to uncover the essential topological requirements for the appearance of QI effects and the relationship between the QI-affected line shape of the transmission spectra and the electronic structures, we consider a homogeneous toy model where all on-site energies are identical and model four types of molecular junctions due to their topological connectivities. We systematically analyze their transmission spectra, density of states, and thermoelectric properties. Even without the degree of freedom for on-site energies an asymmetric Fano peak could be realized in the homogeneous systems with the cyclic configuration. We also calculate the thermoelectric properties of the model systems with and without fluctuation of on-site energies. Even under the fluctuation of the on-site energies, the finite thermoelectrics are preserved for the Fano resonance, thus cyclic configuration is promising for thermoelectric applications. This result also suggests the possibility to detect the cyclic configuration in the homogeneous systems and the presence of the QI features from thermoelectric measurements.

  17. Thermoelectric and Themorectification properties of quantum dot junctions

    Science.gov (United States)

    Kuo, David M.-T.; Chang, Yia-Chung

    2010-03-01

    The electrical conductance, thermal conductance, thermal power and figure of merit (ZT) of semiconductor quantum dots (QDs) embedded in an insulator matrix connected with metallic electrodes are theoretically investigated in the Coulomb blockade regime. The multilevel Anderson model is used to simulate the multiple QDs junction system. The charge and heat currents in the sequence tunneling process are calculated by the Keldysh Green function technique. In the linear response regime the ZT values are still very impressive in the small tunneling rates case, although the effect of electron Coulomb interaction on ZT is significant. Considering the inelastic scattering effect arising from size fluctuations, defects and electron-phonon interactions, the reduction of ZT values is serious. In the nonlinear response regime, the nonlinear heat flow with respect to temperature is observed. When the coupling between the QDs and the electrodes is asymmetrical, we observed a thermal rectification behavior, which is also influenced by the electron Coulomb interactions and energy level differences between the two dots.

  18. Transport through hybrid superconducting/ferromagnetic double-path junction

    Energy Technology Data Exchange (ETDEWEB)

    Facio, T.J.S. [Departamento de Física e Química, Universidade Estadual Paulista – UNESP, 15385-000, Ilha Solteira, SP (Brazil); Orellana, P.A. [Departamento de Física, Universidad Técnica Federico Santa Maria, Av. Vicuña Mackenna, 3939, Santiago (Chile); Jurelo, A.R. [Departamento de Física, Universidade Estadual de Ponta Grossa – UEPG, 84030-000, Ponta Grossa, PR (Brazil); Figueira, M.S. [Instituto de Física, Universidade Federal Fluminense, 24210-340, Niterói, RJ (Brazil); Cabrera, G.G. [Instituto de Física ‘Gleb Wataghin’, Universidade Estadual de Campinas – UNICAMP, 13083-859, Campinas, SP (Brazil); Siqueira, E.C., E-mail: ecosta@utfpr.edu.br [Departamento de Física, Universidade Tecnológica Federal do Paraná – UTFPR, 84016-210, Ponta Grossa, PR (Brazil)

    2017-02-05

    In this paper we study a double-path junction formed by a ferromagnetic and a superconductor lead. The first path connects the superconductor and ferromagnet directly while the second path connects these metals through a quantum dot. The whole system works as an Aharonov–Bohm interferometer allowing the study of the interference between these two paths under the presence of spin imbalance and Andreev bound states. We considered the effect of Fano interference on the electronic transmittance through the quantum dot and observed two regimes of conduction depending on the strength of the direct coupling. For the weak coupling regime, the transmittance presented the usual four resonances due to the Andreev bound states whereas for the strong coupling regime the profile was inverted and resonances became anti-resonances. However, even in the strong coupling regime it was possible to observe a central resonance due to the interference between the Andreev bound states. We have also studied the signatures of Fano interference on the average occupation within the quantum dot. The spin accumulation was analyzed and how it depends on the direct coupling and an external magnetic field applied to the system. The results obtained may be used in a possible experimental implementation of this system in order to probe spin related effects in ferromagnetic superconductor nanostructures. - Highlights: • An Aharonov–Bohm interferometer composed by a quantum-dot coupled to a superconductor and ferromagnetic lead is studied. • The transmittance through the QD is determined by the interplay between Andreev and Fano interference. • Spin accumulation within the quantum dot is studied as a function of bias/gate voltages and an external magnetic flux.

  19. Spectral Flow in Josephson Junctions and Effective Magnus Force

    OpenAIRE

    Makhlin, Yu. G.; Volovik, G. E.

    1995-01-01

    Momentum production during the phase slip process in SNS Josephson junction is discussed. It is caused by the spectral flow of bound states of fermions localized within the junction. This effectively reduces the Magnus force acting on vortices which provides an explanation for the experimental observation of the negligible Magnus force in 2D Josephson junction arrays. The flow of the fermionic levels is similar to that in sphalerons in particle physics, where it gives rise to the baryogenesis.

  20. Magnetic interaction between spatially extended superconducting tunnel junctions

    DEFF Research Database (Denmark)

    Grønbech-Jensen, Niels; Samuelsen, Mogens Rugholm

    2002-01-01

    A general description of magnetic interactions between superconducting tunnel junctions is given. The description covers a wide range of possible experimental systems, and we explicitly explore two experimentally relevant limits of coupled junctions. One is the limit of junctions with tunneling...... been considered through arrays of superconducting weak links based on semiconductor quantum wells with superconducting electrodes. We use the model to make direct interpretations of the published experiments and thereby propose that long-range magnetic interactions are responsible for the reported...

  1. Shottky-barrier formation. Abrupt metal-semiconductor junctions

    Energy Technology Data Exchange (ETDEWEB)

    Guines, F.; Sanchez-Dehesa, J.; Flores, F.

    1983-02-01

    In this paper a realistic self-consistent calculation of an abrupt metal-semiconductor junction is presented by means of a tight-binding approach. A specific Si-Ag junction has been considered, and the charge neutrality level as well as the barrier height have been determined in good agreement with experiments. For a general junction it is shown that the interface properties depend essentially on the characteristics of the first metal layer and its interaction with the semiconductor.

  2. Enteric Pathogens and Their Toxin-Induced Disruption of the Intestinal Barrier through Alteration of Tight Junctions in Chickens.

    Science.gov (United States)

    Awad, Wageha A; Hess, Claudia; Hess, Michael

    2017-02-10

    Maintaining a healthy gut environment is a prerequisite for sustainable animal production. The gut plays a key role in the digestion and absorption of nutrients and constitutes an initial organ exposed to external factors influencing bird's health. The intestinal epithelial barrier serves as the first line of defense between the host and the luminal environment. It consists of a continuous monolayer of intestinal epithelial cells connected by intercellular junctional complexes which shrink the space between adjacent cells. Consequently, free passing of solutes and water via the paracellular pathway is prevented. Tight junctions (TJs) are multi-protein complexes which are crucial for the integrity and function of the epithelial barrier as they not only link cells but also form channels allowing permeation between cells, resulting in epithelial surfaces of different tightness. Tight junction's molecular composition, ultrastructure, and function are regulated differently with regard to physiological and pathological stimuli. Both in vivo and in vitro studies suggest that reduced tight junction integrity greatly results in a condition commonly known as "leaky gut". A loss of barrier integrity allows the translocation of luminal antigens (microbes, toxins) via the mucosa to access the whole body which are normally excluded and subsequently destroys the gut mucosal homeostasis, coinciding with an increased susceptibility to systemic infection, chronic inflammation and malabsorption. There is considerable evidence that the intestinal barrier dysfunction is an important factor contributing to the pathogenicity of some enteric bacteria. It has been shown that some enteric pathogens can induce permeability defects in gut epithelia by altering tight junction proteins, mediated by their toxins. Resolving the strategies that microorganisms use to hijack the functions of tight junctions is important for our understanding of microbial pathogenesis, because some pathogens can

  3. Some chaotic features of intrinsically coupled Josephson junctions

    International Nuclear Information System (INIS)

    Kolahchi, M.R.; Shukrinov, Yu.M.; Hamdipour, M.; Botha, A.E.; Suzuki, M.

    2013-01-01

    Highlights: ► Intrinsically coupled Josephson junctions model a high-T c superconductor. ► Intrinsically coupled Josephson junctions can act as a chaotic nonlinear system. ► Chaos could be due to resonance overlap. ► Avoiding parameters that lead to chaos is important for the design of resonators. -- Abstract: We look for chaos in an intrinsically coupled system of Josephson junctions. This study has direct applications for the high-T c resonators which require coherence amongst the junctions

  4. Towards field theory in spaces with multivolume junctions

    CERN Document Server

    Fomin, P I

    2002-01-01

    We consider a spacetime formed by several pieces with common timelike boundary which plays the role of a junction between them. We establish junction conditions for fields of various spins and derive the resulting laws of wave propagation through the junction, which turn out to be quite similar for fields of all spins. As an application, we consider the case of multivolume junctions in four-dimensional spacetime that may arise in the context of the theory of quantum creation of a closed universe on the background of a big mother universe. The theory developed can also be applied to braneworld models and to the superstring theory.

  5. Gap Junctional Intercellular Communication and Breast Cancer Metastasis to Bone

    National Research Council Canada - National Science Library

    Donahue, Henry

    2001-01-01

    .... We found that: 1) expressing the metastasis suppressing gene BRMS1 in diverse cancer cell lines, including breast and melanoma, restores homotypic gap junctional intercellular communication (GJIC); 2...

  6. Superconducting Tunnel Junction Arrays for UV Photon Detection, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — An innovative method is described for the fabrication of superconducting tunnel junction (STJ) detector arrays offering true "three dimensional" imaging throughout...

  7. Microwave phase locking of Josephson-junction fluxon oscillators

    DEFF Research Database (Denmark)

    Salerno, M.; Samuelsen, Mogens Rugholm; Filatrella, G.

    1990-01-01

    Application of the classic McLaughlin-Scott soliton perturbation theory to a Josephson-junction fluxon subjected to a microwave field that interacts with the fluxon only at the junction boundaries reduces the problem of phase locking of the fluxon oscillation to the study of a two-dimensional fun......Application of the classic McLaughlin-Scott soliton perturbation theory to a Josephson-junction fluxon subjected to a microwave field that interacts with the fluxon only at the junction boundaries reduces the problem of phase locking of the fluxon oscillation to the study of a two...

  8. Mercury cadmium telluride implanted junction profile measurement and depth control

    Science.gov (United States)

    Zhou, Songmin; Lin, Chun; Li, Haibin; Wei, Yanfeng; Ye, Zhenhua; Ding, Ruijun; He, Li

    2014-06-01

    In this work, a novel junction profile measurement method is proposed. A serial of junctions were fabricated by B+ implantation. Then a beveled bar which was about 10mm long and several micrometers deep was formed by carefully controlled wet-etching. The remaining depth of n region changes from the full depth that is about 5.3mm after ion implantation to zero depending on its lateral position and the slope of the etching bar. Voltage-current and Laser Beam Induced Current (LBIC) measurements were applied to determine the HgCdTe junction edge. The LBIC signal orrectification characteristic indicates the existence of a PN junction. The junction depth is extracted from the position where the PN junction disappears and the slope of the etching bar. The junction depth of intrinsic doped HgCdTe was measured, which is about 2.4μm. A significant 0.4mm thick N-region was observed. Moreover, junction depths of samples annealed for different time were also investigated. By this method, it's possible to measure the three dimensional profile of a planar PN junction.

  9. Spectrum of resonant plasma oscillations in long Josephson junctions

    International Nuclear Information System (INIS)

    Holst, T.

    1996-01-01

    An analysis is presented for the amplitude of the plasma oscillations in the zero-voltage state of a long and narrow Josephson tunnel junction. The calculation is valid for arbitrary normalized junction length and arbitrary bias current. The spectrum of the plasma resonance is found numerically as solutions to an analytical equation. The low-frequency part of the spectrum contains a single resonance, which is known to exist also in the limit of a short and narrow junction. Above a certain cutoff frequency, a series of high-frequency standing wave plasma resonances is excited, a special feature of long Josephson junctions. copyright 1996 The American Physical Society

  10. Effect of junction configurations on microdroplet formation in a T-junction microchannel

    Science.gov (United States)

    Lih, F. L.; Miao, J. M.

    2015-03-01

    This study investigates the dynamic formation process of water microdroplets in a silicon oil flow in a T-junction microchannel. Segmented water microdroplets are formed at the junction when the water flow is perpendicularly injected into the silicon oil flow in a straight rectangular microchannel. This study further presents the effects of the water flow inlet geometry on hydrodynamic characteristics of water microdroplet formation. A numerical multiphase volume of fluid (VOF) scheme is coupled to solve the unsteady three-dimensional laminar Navier-Stokes equations to depict the droplet formation phenomena at the junction. Predicted results on the length and generated frequency of the microdroplets agree well with experimental results in a T-junction microchannel with straight and flat inlets (the base model) for both fluid flows. Empirical correlations are reported between the volumetric flow ratio and the dimensionless microdroplet length or dimensionless frequency of droplet generation at a fixed capillary number of 4.7 · 10-3. The results of this study indicate a reduction in the droplet length of approximately 21% if the straight inlet for the water flow is modified to a downstream sudden contraction inlet for the water flow.

  11. A unified framework for spiking and gap-junction interactions in distributed neuronal network simulations

    Directory of Open Access Journals (Sweden)

    Jan eHahne

    2015-09-01

    Full Text Available Contemporary simulators for networks of point and few-compartment model neurons come with a plethora of ready-to-use neuron and synapse models and support complex network topologies. Recent technological advancements have broadened the spectrum of application further to the efficient simulation of brain-scale networks on supercomputers. In distributed network simulations the amount of spike data that accrues per millisecond and process is typically low, such that a common optimization strategy is to communicate spikes at relatively long intervals, where the upper limit is given by the shortest synaptic transmission delay in the network. This approach is well-suited for simulations that employ only chemical synapses but it has so far impeded the incorporation of gap-junction models, which require instantaneous neuronal interactions. Here, we present a numerical algorithm based on a waveform-relaxation technique which allows for network simulations with gap junctions in a way that is compatible with the delayed communication strategy. Using a reference implementation in the NEST simulator, we demonstrate that the algorithm and the required data structures can be smoothly integrated with existing code such that they complement the infrastructure for spiking connections. To show that the unified framework for gap-junction and spiking interactions achieves high performance and delivers high accuracy...

  12. An investigation of wall temperature characteristics to evaluate thermal fatigue at a T-junction pipe

    International Nuclear Information System (INIS)

    Miyoshi, Koji; Nakamura, Akira; Utanohara, Yoichi; Takenaka, Nobuyuki

    2014-01-01

    Thermal fatigue cracking may initiate at a T-junction pipe where high and low temperature fluids mix. In this study, wall temperature characteristics at a T-junction pipe were investigated to improve the evaluation method for thermal fatigue. The stainless steel test section consisted of a horizontal main pipe (diameter, 150 mm) and a T-junction connected to a vertical branch pipe (diameter, 50 mm). The inlet flow velocities in the main and branch pipes were set to 0.99 m/s and 0.66 m/s respectively to produce a wall jet pattern in which the jet from the branch pipe was bent by the main pipe flow and made to flow along the pipe wall. The temperature difference was 34.1 K. A total of 148 thermocouples were installed to measure the wall temperature on the pipe inner surface in the downstream region. The maximum of temperature fluctuation intensity on the pipe inner surface was measured as 5% of the fluid temperature difference at the inlets. The dominant frequency of the large temperature fluctuations in the region downstream from z = 0.5D m was equal to 0.2 of the Strouhal number, which was equal to the frequency caused by the vortex streets generated around the jet flow. The large temperature fluctuation was also observed with the period of about 10 s. The fluctuation was caused by spreading of the heated region in the circumferential direction. (author)

  13. Eye lens membrane junctional microdomains: a comparison between healthy and pathological cases

    Energy Technology Data Exchange (ETDEWEB)

    Buzhynskyy, Nikolay; Scheuring, Simon [Institut Curie, Equipe Inserm Avenir, UMR168-CNRS, 26 Rue d' Ulm, 75248 Paris Cedex 05 (France); Sens, Pierre [ESPCI, CNRS-UMR 7083, 75231 Paris (France); Behar-Cohen, Francine, E-mail: simon.scheuring@curie.fr [UMRS Inserm 872, Universite Paris Descartes, Centre de Recherches des Cordeliers, 15 rue de l' Ecole de Medecine, 75270 Paris Cedex 06 (France)

    2011-08-15

    The eye lens is a transparent tissue constituted of tightly packed fiber cells. To maintain homeostasis and transparency of the lens, the circulation of water, ions and metabolites is required. Junctional microdomains connect the lens cells and ensure both tight cell-to-cell adhesion and intercellular flow of fluids through a microcirculation system. Here, we overview membrane morphology and tissue functional requirements of the mammalian lens. Atomic force microscopy (AFM) has opened up the possibility of visualizing the junctional microdomains at unprecedented submolecular resolution, revealing the supramolecular assembly of lens-specific aquaporin-0 (AQP0) and connexins (Cx). We compare the membrane protein assembly in healthy lenses with senile and diabetes-II cataract cases and novel data of the lens membranes from a congenital cataract. In the healthy case, AQP0s form characteristic square arrays confined by connexons. In the cases of senile and diabetes-II cataract patients, connexons were degraded, leading to malformation of AQP0 arrays and breakdown of the microcirculation system. In the congenital cataract, connexons are present, indicating probable non-membranous grounds for lens opacification. Further, we discuss the energetic aspects of the membrane organization in junctional microdomains. The AFM hence becomes a biomedical nano-imaging tool for the analysis of single-membrane protein supramolecular association in healthy and pathological membranes.

  14. Eye lens membrane junctional microdomains: a comparison between healthy and pathological cases

    Science.gov (United States)

    Buzhynskyy, Nikolay; Sens, Pierre; Behar-Cohen, Francine; Scheuring, Simon

    2011-08-01

    The eye lens is a transparent tissue constituted of tightly packed fiber cells. To maintain homeostasis and transparency of the lens, the circulation of water, ions and metabolites is required. Junctional microdomains connect the lens cells and ensure both tight cell-to-cell adhesion and intercellular flow of fluids through a microcirculation system. Here, we overview membrane morphology and tissue functional requirements of the mammalian lens. Atomic force microscopy (AFM) has opened up the possibility of visualizing the junctional microdomains at unprecedented submolecular resolution, revealing the supramolecular assembly of lens-specific aquaporin-0 (AQP0) and connexins (Cx). We compare the membrane protein assembly in healthy lenses with senile and diabetes-II cataract cases and novel data of the lens membranes from a congenital cataract. In the healthy case, AQP0s form characteristic square arrays confined by connexons. In the cases of senile and diabetes-II cataract patients, connexons were degraded, leading to malformation of AQP0 arrays and breakdown of the microcirculation system. In the congenital cataract, connexons are present, indicating probable non-membranous grounds for lens opacification. Further, we discuss the energetic aspects of the membrane organization in junctional microdomains. The AFM hence becomes a biomedical nano-imaging tool for the analysis of single-membrane protein supramolecular association in healthy and pathological membranes.

  15. Atomistic simulations of highly conductive molecular transport junctions under realistic conditions

    KAUST Repository

    French, William R.

    2013-01-01

    We report state-of-the-art atomistic simulations combined with high-fidelity conductance calculations to probe structure-conductance relationships in Au-benzenedithiolate (BDT)-Au junctions under elongation. Our results demonstrate that large increases in conductance are associated with the formation of monatomic chains (MACs) of Au atoms directly connected to BDT. An analysis of the electronic structure of the simulated junctions reveals that enhancement in the s-like states in Au MACs causes the increases in conductance. Other structures also result in increased conductance but are too short-lived to be detected in experiment, while MACs remain stable for long simulation times. Examinations of thermally evolved junctions with and without MACs show negligible overlap between conductance histograms, indicating that the increase in conductance is related to this unique structural change and not thermal fluctuation. These results, which provide an excellent explanation for a recently observed anomalous experimental result [Bruot et al., Nat. Nanotechnol., 2012, 7, 35-40], should aid in the development of mechanically responsive molecular electronic devices. © 2013 The Royal Society of Chemistry.

  16. Performance Evaluation of Moment Connections of Moment Resisting Frames Against Progressive Collapse

    Directory of Open Access Journals (Sweden)

    M. Mahmoudi

    2017-02-01

    Full Text Available When a primary structural element fails due to sudden load such as explosion, the building undergoes progressive collapse. The method for design of moment connections during progressive collapse is different to seismic design of moment connections. Because in this case, the axial force on the connections makes it behave differently. The purpose of this paper is to evaluate the performance of a variety of moment connections in preventing progressive collapse in steel moment frames. To achieve this goal, three prequalified moment connections (BSEEP, BFP and WUP-W were designed according seismic codes. These moment connections were analyzed numerically using ABAQUS software for progressive collapse. The results show that the BFP connection (bolted flange plate has capacity much more than other connections because of the use of plates at the junction of beam-column.

  17. Connected vehicle standards.

    Science.gov (United States)

    2016-01-01

    Connected vehicles have the potential to transform the way Americans travel by : allowing cars, buses, trucks, trains, traffic signals, smart phones, and other devices to : communicate through a safe, interoperable wireless network. A connected vehic...

  18. Molecular Diffusion through Cyanobacterial Septal Junctions

    Directory of Open Access Journals (Sweden)

    Mercedes Nieves-Morión

    2017-01-01

    Full Text Available Heterocyst-forming cyanobacteria grow as filaments in which intercellular molecular exchange takes place. During the differentiation of N2-fixing heterocysts, regulators are transferred between cells. In the diazotrophic filament, vegetative cells that fix CO2 through oxygenic photosynthesis provide the heterocysts with reduced carbon and heterocysts provide the vegetative cells with fixed nitrogen. Intercellular molecular transfer has been traced with fluorescent markers, including calcein, 5-carboxyfluorescein, and the sucrose analogue esculin, which are observed to move down their concentration gradient. In this work, we used fluorescence recovery after photobleaching (FRAP assays in the model heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 to measure the temperature dependence of intercellular transfer of fluorescent markers. We find that the transfer rate constants are directly proportional to the absolute temperature. This indicates that the “septal junctions” (formerly known as “microplasmodesmata” linking the cells in the filament allow molecular exchange by simple diffusion, without any activated intermediate state. This constitutes a novel mechanism for molecular transfer across the bacterial cytoplasmic membrane, in addition to previously characterized mechanisms for active transport and facilitated diffusion. Cyanobacterial septal junctions are functionally analogous to the gap junctions of metazoans.

  19. Concept and design of super junction devices

    Science.gov (United States)

    Zhang, Bo; Zhang, Wentong; Qiao, Ming; Zhan, Zhenya; Li, Zhaoji

    2018-02-01

    The super junction (SJ) has been recognized as the " milestone” of the power MOSFET, which is the most important innovation concept of the voltage-sustaining layer (VSL). The basic structure of the SJ is a typical junction-type VSL (J-VSL) with the periodic N and P regions. However, the conventional VSL is a typical resistance-type VSL (R-VSL) with only an N or P region. It is a qualitative change of the VSL from the R-VSL to the J-VSL, introducing the bulk depletion to increase the doping concentration and optimize the bulk electric field of the SJ. This paper firstly summarizes the development of the SJ, and then the optimization theory of the SJ is discussed for both the vertical and the lateral devices, including the non-full depletion mode, the minimum specific on-resistance optimization method and the equivalent substrate model. The SJ concept breaks the conventional " silicon limit” relationship of R on∝V B 2.5, showing a quasi-linear relationship of R on∝V B 1.03.

  20. GAP junctional communication in brain secondary organizers.

    Science.gov (United States)

    Bosone, Camilla; Andreu, Abraham; Echevarria, Diego

    2016-06-01

    Gap junctions (GJs) are integral membrane proteins that enable the direct cytoplasmic exchange of ions and low molecular weight metabolites between adjacent cells. They are formed by the apposition of two connexons belonging to adjacent cells. Each connexon is formed by six proteins, named connexins (Cxs). Current evidence suggests that gap junctions play an important part in ensuring normal embryo development. Mutations in connexin genes have been linked to a variety of human diseases, although the precise role and the cell biological mechanisms of their action remain almost unknown. Among the big family of Cxs, several are expressed in nervous tissue but just a few are expressed in the anterior neural tube of vertebrates. Many efforts have been made to elucidate the molecular bases of Cxs cell biology and how they influence the morphogenetic signal activity produced by brain signaling centers. These centers, orchestrated by transcription factors and morphogenes determine the axial patterning of the mammalian brain during its specification and regionalization. The present review revisits the findings of GJ composed by Cx43 and Cx36 in neural tube patterning and discuss Cx43 putative enrollment in the control of Fgf8 signal activity coming from the well known secondary organizer, the isthmic organizer. © 2016 The Authors. Development, Growth & Differentiation published by John Wiley & Sons Australia, Ltd on behalf of Japanese Society of Developmental Biologists.

  1. Electrophysiological study in neuromuscular junction disorders

    Directory of Open Access Journals (Sweden)

    Ajith Cherian

    2013-01-01

    Full Text Available This review is on ultrastructure and subcellular physiology at normal and abnormal neuromuscular junctions. The clinical and electrophysiological findings in myasthenia gravis, Lambert-Eaton myasthenic syndrome (LEMS, congenital myasthenic syndromes, and botulinum intoxication are discussed. Single fiber electromyography (SFEMG helps to explain the basis of testing neuromuscular junction function by repetitive nerve stimulation (RNS. SFEMG requires skill and patience and its availability is limited to a few centers. For RNS supramaximal stimulation is essential and so is display of the whole waveform of each muscle response at maximum amplitude. The amplitudes of the negative phase of the first and fourth responses are measured from baseline to negative peak, and the percent change of the fourth response compared with the first represents the decrement or increment. A decrement greater than 10% is accepted as abnormal and smooth progression of response amplitude train and reproducibility form the crux. In suspected LEMS the effect of fast rates of stimulation should be determined after RNS response to slow rates of stimulation. Caution is required to avoid misinterpretation of potentiation and pseudofacilitation.

  2. Angular craniometry in craniocervical junction malformation.

    Science.gov (United States)

    Botelho, Ricardo Vieira; Ferreira, Edson Dener Zandonadi

    2013-10-01

    The craniometric linear dimensions of the posterior fossa have been relatively well studied, but angular craniometry has been poorly studied and may reveal differences in the several types of craniocervical junction malformation. The objectives of this study were to evaluate craniometric angles compared with normal subjects and elucidate the main angular differences among the types of craniocervical junction malformation and the correlation between craniocervical and cervical angles. Angular craniometries were studied using primary cranial angles (basal and Boogard's) and secondary craniocervical angles (clivus canal and cervical spine lordosis). Patients with basilar invagination had significantly wider basal angles, sharper clivus canal angles, larger Boogard's angles, and greater cervical lordosis than the Chiari malformation and control groups. The Chiari malformation group does not show significant differences when compared with normal controls. Platybasia occurred only in basilar invagination and is suggested to be more prevalent in type II than in type I. Platybasic patients have a more acute clivus canal angle and show greater cervical lordosis than non-platybasics. The Chiari group does not show significant differences when compared with the control, but the basilar invagination groups had craniometric variables significantly different from normal controls. Hyperlordosis observed in the basilar inavagination group was associated with craniocervical kyphosis conditioned by acute clivus canal angles.

  3. Electron Transport through Porphyrin Molecular Junctions

    Science.gov (United States)

    Zhou, Qi

    The goal of this work is to study the properties that would affect the electron transport through a porphyrin molecular junction. This work contributes to the field of electron transport in molecular junctions in the following 3 aspects. First of all, by carrying out experiments comparing the conductance of the iron (III) porphyrin (protected) and the free base porphyrin (protected), it is confirmed that the molecular energy level broadening and shifting occurs for porphyrin molecules when coupled with the metal electrodes, and this level broadening and shifting plays an important role in the electron transport through molecular junctions. Secondly, by carrying out an in-situ deprotection of the acetyl-protected free base porphyrin molecules, it is found out that the presence of acetyl groups reduces the conductance. Thirdly, by incorporating the Matrix-assisted laser desorption/ionization (MALDI) spectrum and the in-situ deprotection prior to formation of molecular junctions, it allows a more precise understanding of the molecules involved in the formation of molecular junctions, and therefore allows an accurate analysis of the conductance histogram. The molecules are prepared by self-assembly and the junctions are formed using a Scanning Tunneling Microscopy (STM) molecular break junction technique. The porphyrin molecules are characterized by MALDI in solution before self-assembly to a gold/mica substrate. The self-assembled monolayers (SAMs) of porphyrins on gold are characterized by Ultraviolet-visible (UV-Vis) reflection spectroscopy to confirm that the molecules are attached to the substrate. The SAMs are then characterized by Angle-Resolved X-ray photoelectron spectroscopy (ARXPS) to determine the thickness and the average molecular orientation of the molecular layer. The electron transport is measured by conductance-displacement (G-S) experiments under a given bias (-0.4V). The conductance value of a single molecule is identified by a statistical analysis

  4. Connecting to Everyday Practices

    DEFF Research Database (Denmark)

    Iversen, Ole Sejer; Smith, Rachel Charlotte

    2012-01-01

    construction and reproduction of cultural heritage creating novel connections between self and others and between past, present and future. We present experiences from a current research project, the Digital Natives exhibition, in which social media was designed as an integral part of the exhibition to connect...... focusing on the connections between audiences practices and the museum exhibition....

  5. Dynamics of the Josephson multi-junction system with junctions characterized by non-sinusoidal current - phase relationship

    International Nuclear Information System (INIS)

    Abal'osheva, I.; Lewandowski, S.J.

    2004-01-01

    It is shown that the inclusion of junctions characterized by non-sinusoidal current - phase relationship in the systems composed of multiple Josephson junctions - results in the appearance of additional system phase states. Numerical simulations and stability considerations confirm that those phase states can be realized in practice. Moreover, spontaneous formation of the grain boundary junctions in high-T c superconductors with non-trivial current-phase relations due to the d-wave symmetry of the order parameter is probable. Switching between the phase states of multiple grain boundary junction systems can lead to additional 1/f noise in high-T c superconductors. (author)

  6. Single Molecule Nanoelectrochemistry in Electrical Junctions.

    Science.gov (United States)

    Nichols, Richard J; Higgins, Simon J

    2016-11-15

    It is now possible to reliably measure single molecule conductance in a wide variety of environments including organic liquids, ultrahigh vacuum, water, ionic liquids, and electrolytes. The most commonly used methods deploy scanning probe microscopes, mechanically formed break junctions, or lithographically formed nanogap contacts. Molecules are generally captured between a pair of facing electrodes, and the junction current response is measured as a function of bias voltage. Gating electrodes can also be added so that the electrostatic potential at the molecular bridge can be independently controlled by this third noncontacting electrode. This can also be achieved in an electrolytic environment using a four-electrode bipotentiostatic configuration, which allows independent electrode potential control of the two contacting electrodes. This is commonly realized using an electrochemical STM and enables single molecule electrical characterization as a function of electrode potential and redox state of the molecular bridge. This has emerged as a powerful tool in modern interfacial electrochemistry and nanoelectrochemistry for studying charge transport across single molecules as a function of electrode potential and the electrolytic environments. Such measurements are possible in electrolytes ranging from aqueous buffers to nonaqueous ionic liquids. In this Account, we illustrate a number of examples of single molecule electrical measurements under electrode potential control use a scanning tunneling microscope (STM) and demonstrate how these can help in the understanding of charge transport in single molecule junctions. Examples showing charge transport following phase coherent tunneling to incoherent charge hopping across redox active molecular bridges are shown. In the case of bipyridinium (or viologen) molecular wires, it is shown how electrochemical reduction leads to an increase of the single molecule conductance, which is controlled by the liquid electrochemical

  7. Phase locked fluxon-antifluxon states in stacked Josephson junctions

    DEFF Research Database (Denmark)

    Carapella, Giovanni; Constabile, Giovanni; Petraglia, Antonio

    1996-01-01

    Measurements were made on a two-stack long Josephson junction with very similar parameters and electrical access to the thin middle electrode. Mutually phase-locked fluxon-antifluxon states were observed. The observed propagation velocity is in agreement with the theoretical prediction. The I-V c...... in the junctions coexist with fluxons. (C) 1996 American Institute of Physics....

  8. Diencephalic-Mesencephalic Junction Dysplasia: A Novel Recessive Brain Malformation

    Science.gov (United States)

    Zaki, Maha S.; Saleem, Sahar N.; Dobyns, William B.; Barkovich, A. James; Bartsch, Hauke; Dale, Anders M.; Ashtari, Manzar; Akizu, Naiara; Gleeson, Joseph G.; Grijalvo-Perez, Ana Maria

    2012-01-01

    We describe six cases from three unrelated consanguineous Egyptian families with a novel characteristic brain malformation at the level of the diencephalic-mesencephalic junction. Brain magnetic resonance imaging demonstrated a dysplasia of the diencephalic-mesencephalic junction with a characteristic "butterfly"-like contour of the…

  9. Parametric excitation of plasma oscillations in a Josephson tunnel junction

    DEFF Research Database (Denmark)

    Bak, Christen Kjeldahl; Kofoed, Bent; Pedersen, Niels Falsig

    1975-01-01

    Experimental evidence for subharmonic parametric excitation of plasma oscillations in Josephson tunnel junctions is presented. The experiments described are performed by measuring the microwave power necessary to switch a Josephson−tunnel junction biased in the zero−voltage state to a finite−volt......−voltage state. Journal of Applied Physics is copyrighted by The American Institute of Physics....

  10. Processing of Superconductor-Normal-Superconductor Josephson Edge Junctions

    Science.gov (United States)

    Kleinsasser, A. W.; Barner, J. B.

    1997-01-01

    The electrical behavior of epitaxial superconductor-normal-superconductor (SNS) Josephson edge junctions is strongly affected by processing conditions. Ex-situ processes, utilizing photoresist and polyimide/photoresist mask layers, are employed for ion milling edges for junctions with Yttrium-Barium-Copper-Oxide (YBCO) electrodes and primarily Co-doped YBCO interlayers.

  11. 75 FR 76294 - Radio Broadcasting Services: Pacific Junction, IA

    Science.gov (United States)

    2010-12-08

    ... FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 73 [DA 10-2236; MB Docket No. 10-108] Radio Broadcasting Services: Pacific Junction, IA AGENCY: Federal Communications Commission. ACTION: Final rule. SUMMARY: The staff deletes FM Channel 299C2 at Pacific Junction, Iowa, because the record in this...

  12. Immersed boundary simulation of flow through arterial junctions

    Indian Academy of Sciences (India)

    Dwaipayan Sarkar

    Simulations are further carried out for pulsated flows and effects of blockages near the junctions (due to stenosis or atherosclerosis). Instabilities in the flow structures near the junction and the resulting changes in the downstream pulsation frequency were observed. These changes account for the physiological heart defects ...

  13. Spin-polarized magnetic tunnelling magnetoresistive effects in various junctions

    Science.gov (United States)

    Miyazaki, T.; Tezuka, N.; Kumagai, S.; Ando, Y.; Kubota, H.; Murai, J.; Watabe, T.; Yokota, M.

    1998-03-01

    Recent progress concerning spin-polarized magnetic tunnelling effects for (i) trilayer standard ferromagnet (F)/insulator (I)/ferromagnet (F) junctions, (ii) spin-valve-type junctions, (iii) trilayer or multilayer ferromagnet/granular/ferromagnet junctions and (iv) F/I/F junction with a `wedge-geometry' insulator is reviewed. Special emphasis is placed on the dependence of the tunnel magnetoresistance ratio on temperature and also the intensity of the applied voltage. It was found that the resistance for the saturation magnetization state, 0022-3727/31/6/009/img1, and the tunnelling magnetoresistance ratio, TMR, of an 0022-3727/31/6/009/img2 junction decreased rapidly with increasing temperature, whereas those of a 0022-3727/31/6/009/img3 junction were insensitive to temperature. Concerning the bias voltage dependence of 0022-3727/31/6/009/img1 and TMR, the same tendency with temperature was observed for 0022-3727/31/6/009/img2 and 0022-3727/31/6/009/img3 junctions. Spin-valve-type junction exchange biased by a FeMn layer exhibits a relatively large TMR ratio up to about 400 K.

  14. Specific Contact Resistance Measurements of Metal Semiconductor-Junctions

    NARCIS (Netherlands)

    Stavitski, N.; van Dal, M.J.H.; Wolters, Robertus A.M.; Kovalgin, Alexeij Y.; Schmitz, Jurriaan

    2006-01-01

    Our research comprises the manufacturing of test structures to characterize the metal-semiconductor junctions with a number of techniques and materials. An extensive subsequent physical and electrical testing of the junctions is carried out. We present our first results on specific

  15. Tunnel junction dc SQUID: fabrication, operation, and performance

    International Nuclear Information System (INIS)

    Clarke, J.; Goubau, W.M.; Ketchen, M.B.

    1976-01-01

    The theory, fabrication, operation, and performance of a dc SQUID that makes use of two shunted Nb-NbO/sub x/-Pb tunnel junctions are described. The junctions have predictable characteristics, can be stored for long periods at room temperature, and can be cycled between room and liquid helium temperatures repeatedly

  16. Frequency Windows of Absolute Negative Conductance in Josephson Junctions

    OpenAIRE

    Machura, L.; Kostur, M.; Talkner, P.; Hanggi, P.; Luczka, J.

    2007-01-01

    We report on anomalous conductance in a resistively and capacitively shunted Josephson junction which is simultaneously driven by ac and dc currents. The dependence of the voltage across the junction on the frequency of the ac current shows windows of absolute negative conductance regimes, i.e. for a positive (negative) dc current, the voltage is negative (positive).

  17. Shapiro and parametric resonances in coupled Josephson junctions

    International Nuclear Information System (INIS)

    Gaafar, Ma A; Shukrinov, Yu M; Foda, A

    2012-01-01

    The effect of microwave irradiation on the phase dynamics of intrinsic Josephson junctions in high temperature superconductors is investigated. We compare the current-voltage characteristics for a stack of coupled Josephson junctions under external irradiation calculated in the framework of CCJJ and CCJJ+DC models.

  18. Towards molecular electronics with large-area molecular junctions

    NARCIS (Netherlands)

    Akkerman, HB; Blom, PWM; de Leeuw, DM; de Boer, B

    2006-01-01

    Electronic transport through single molecules has been studied extensively by academic(1-8) and industrial(9,10) research groups. Discrete tunnel junctions, or molecular diodes, have been reported using scanning probes(11,12), break junctions(13,14), metallic crossbars(6) and nanopores(8,15). For

  19. Preparation of CN x /Carbon Nanotube Intramolecular Junctions by ...

    African Journals Online (AJOL)

    Preparation of CN x /Carbon Nanotube Intramolecular Junctions by Switching Gas Sources in Continuous Chemical Vapour Deposition. ... nanotubes were observed, and such different structures at both sides of the junctions indicated some interesting properties and offered potential applications for future nanodevices.

  20. Response of high Tc superconducting Josephson junction to nuclear radiation

    International Nuclear Information System (INIS)

    Ding Honglin; Zhang Wanchang; Zhang Xiufeng

    1992-10-01

    The development of nuclear radiation detectors and research on high T c superconducting nuclear radiation detectors are introduced. The emphases are the principle of using thin-film and thick-film Josephson junctions (bridge junction) based on high T c YBCO superconductors to detect nuclear radiation, the fabrication of thin film and thick-film Josephson junction, and response of junction to low energy gamma-rays of 59.5 keV emitted from 241 Am and beta-rays of 546 keV. The results show that a detector for measuring nuclear radiation spectrum made of high T c superconducting thin-film or thick-film, especially, thick-film Josephson junction, certainly can be developed

  1. Spatially resolved detection of mutually locked Josephson junctions in arrays

    International Nuclear Information System (INIS)

    Keck, M.; Doderer, T.; Huebener, R.P.; Traeuble, T.; Dolata, R.; Weimann, T.; Niemeyer, J.

    1997-01-01

    Mutual locking due to the internal coupling in two-dimensional arrays of Josephson junctions was investigated. The appearance of Shapiro steps in the current versus voltage curve of a coupled on-chip detector junction is used to indicate coherent oscillations in the array. A highly coherent state is observed for some range of the array bias current. By scanning the array with a low-power electron beam, mutually locked junctions remain locked while the unlocked junctions generate a beam-induced additional voltage drop at the array. This imaging technique allows the detection of the nonlocked or weakly locked Josephson junctions in a (partially) locked array state. copyright 1997 American Institute of Physics

  2. Shunted-Josephson-junction model. II. The nonautonomous case

    DEFF Research Database (Denmark)

    Belykh, V. N.; Pedersen, Niels Falsig; Sørensen, O. H.

    1977-01-01

    The shunted-Josephson-junction model with a monochromatic ac current drive is discussed employing the qualitative methods of the theory of nonlinear oscillations. As in the preceding paper dealing with the autonomous junction, the model includes a phase-dependent conductance and a shunt capacitance....... The mathematical discussion makes use of the phase-space representation of the solutions to the differential equation. The behavior of the trajectories in phase space is described for different characteristic regions in parameter space and the associated features of the junction IV curve to be expected are pointed...... out. The main objective is to provide a qualitative understanding of the junction behavior, to clarify which kinds of properties may be derived from the shunted-junction model, and to specify the relative arrangement of the important domains in the parameter-space decomposition....

  3. Functional Molecular Junctions Derived from Double Self-Assembled Monolayers.

    Science.gov (United States)

    Seo, Sohyeon; Hwang, Eunhee; Cho, Yunhee; Lee, Junghyun; Lee, Hyoyoung

    2017-09-25

    Information processing using molecular junctions is becoming more important as devices are miniaturized to the nanoscale. Herein, we report functional molecular junctions derived from double self-assembled monolayers (SAMs) intercalated between soft graphene electrodes. Newly assembled molecular junctions are fabricated by placing a molecular SAM/(top) electrode on another molecular SAM/(bottom) electrode by using a contact-assembly technique. Double SAMs can provide tunneling conjugation across the van der Waals gap between the terminals of each monolayer and exhibit new electrical functions. Robust contact-assembled molecular junctions can act as platforms for the development of equivalent contact molecular junctions between top and bottom electrodes, which can be applied independently to different kinds of molecules to enhance either the structural complexity or the assembly properties of molecules. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Surface-Enhanced Raman Scattering in Molecular Junctions.

    Science.gov (United States)

    Iwane, Madoka; Fujii, Shintaro; Kiguchi, Manabu

    2017-08-18

    Surface-enhanced Raman scattering (SERS) is a surface-sensitive vibrational spectroscopy that allows Raman spectroscopy on a single molecular scale. Here, we present a review of SERS from molecular junctions, in which a single molecule or molecules are made to have contact from the top to the bottom of metal surfaces. The molecular junctions are nice platforms for SERS as well as transport measurement. Electronic characterization based on the transport measurements of molecular junctions has been extensively studied for the development of miniaturized electronic devices. Simultaneous SERS and transport measurement of the molecular junctions allow both structural (geometrical) and electronic information on the single molecule scale. The improvement of SERS measurement on molecular junctions open the door toward new nanoscience and nanotechnology in molecular electronics.

  5. Variability metrics in Josephson Junction fabrication for Quantum Computing circuits

    Science.gov (United States)

    Rosenblatt, Sami; Hertzberg, Jared; Brink, Markus; Chow, Jerry; Gambetta, Jay; Leng, Zhaoqi; Houck, Andrew; Nelson, J. J.; Plourde, Britton; Wu, Xian; Lake, Russell; Shainline, Jeff; Pappas, David; Patel, Umeshkumar; McDermott, Robert

    Multi-qubit gates depend on the relative frequencies of the qubits. To reliably build multi-qubit devices therefore requires careful fabrication of Josephson junctions in order to precisely set their critical currents. The Ambegaokar-Baratoff relation between tunnel conductance and critical current implies a correlation between qubit frequency spread and tunnel junction resistance spread. Here we discuss measurement of large numbers of tunnel junctions to assess these resistance spreads, which can exceed 5% of mean resistance. With the goal of minimizing these spreads, we investigate process parameters such as lithographic junction area, evaporation and masking scheme, oxidation conditions, and substrate choice, as well as test environment, design and setup. In addition, trends of junction resistance with temperature are compared with theoretical models for further insights into process and test variability.

  6. Magnetic field behavior of current steps in long Josephson junctions

    International Nuclear Information System (INIS)

    Costabile, G.; Cucolo, A.M.; Pace, S.; Parmentier, R.D.; Savo, B.; Vaglio, R.

    1980-01-01

    The zero-field steps, or dc current singularities, in the current-voltage characteristics of long Josephson tunnel junctions, first reported by Chen et al., continue to attract research interest both because their study can provide fundamental information on the dynamics of fluxons in such junctions and because they are accompanied by the emission of microwave radiation from the junction, which may be exploitable in practical oscillator applications. The purpose of this paper is to report some experimental observations of the magnetic field behavior of the steps in junctions fabricated in our Laboratory and to offer a qualitative explanation for this behavior. Measurements have been made both for very long (L >> lambdasub(J)) and for slightly long (L approx. >= lambdasub(J)) junctions with a view toward comparing our results with those of other workers. (orig./WRI)

  7. Development of myotendinous-like junctions that anchor cardiac valves requires fibromodulin and lumican.

    Science.gov (United States)

    Dupuis, Loren E; Doucette, Lorna; Rice, A Kittrell; Lancaster, Ashton E; Berger, Matthew G; Chakravarti, Shukti; Kern, Christine B

    2016-10-01

    There are many patients that exhibit connective tissue related cardiac malformations but do not have mutations in collagen genes. The Small Leucine Rich Proteoglycans (SLRP) fibromodulin (FMOD) and lumican (LUM) bind collagen and regulate fibril assembly in other biological contexts. FMOD deficient mice and double deficient FMOD; LUM mice exhibited anomalies in regions where cardiac valve tissue interdigitates with adjacent muscle for support. Ectopic connective and/or myocardial tissue(s) was associated with the more severe cardiac valve anomalies in FMOD; LUM deficient mice. At postnatal day 0 (P0) there was an increase in the mesenchymal cell number in the regions where valve cusps anchor in FMOD; LUM deficient mice compared to WT. The cardiac valve anomalies correlated with the highest levels of FMOD expression in the heart and also where myotendinous junctions (MTJ) components biglycan, collagen type I alpha 1, and collagen type VI, are also localized. The postnatal assembly of the collagen-rich ECM in regions where cardiac valves anchor, that we have designated 'myotendinous-like junctions' (MTLJ) requires the SLRPs FMOD and LUM. Moreover, FMOD and LUM may facilitate mesenchymal cell differentiation in late stages of cardiac valve development. Developmental Dynamics 245:1029-1042, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  8. RF assisted switching in magnetic Josephson junctions

    Science.gov (United States)

    Caruso, R.; Massarotti, D.; Bolginov, V. V.; Ben Hamida, A.; Karelina, L. N.; Miano, A.; Vernik, I. V.; Tafuri, F.; Ryazanov, V. V.; Mukhanov, O. A.; Pepe, G. P.

    2018-04-01

    We test the effect of an external RF field on the switching processes of magnetic Josephson junctions (MJJs) suitable for the realization of fast, scalable cryogenic memories compatible with Single Flux Quantum logic. We show that the combined application of microwaves and magnetic field pulses can improve the performances of the device, increasing the separation between the critical current levels corresponding to logical "0" and "1." The enhancement of the current level separation can be as high as 80% using an optimal set of parameters. We demonstrate that external RF fields can be used as an additional tool to manipulate the memory states, and we expect that this approach may lead to the development of new methods of selecting MJJs and manipulating their states in memory arrays for various applications.

  9. [Change in management of ureteropelvic junction obstruction].

    Science.gov (United States)

    Buisson, P; Ricard, J; Boudailliez, B; Canarelli, J P

    2003-03-01

    The aim of this study was to evaluate the change in ureteropelvic junction management, from surgical correction to observation of the hydronephrosis. We checked wether or not it was deleterious for kidney. We retrospectively reviewed 96 charts between 1988 and 1998. Initial ultrasonography, and voiding cystourethrogram were available for all cases. Intravenous urography and diuretic renography were studied when available. Minimal follow-up of patients was one year. Patients were divided into three groups: surgery right away, surgery after observation, and observation only. Later was the diagnosis, more significant were the hydronephrosis and impairment of renal function (p 0.05), and were not predictive of their course. Initial non operative management of hydronephrosis was not dangerous for renal function. It is advisable to detect at the earliest all signs of obstruction, because surgery improves renal drainage but not renal function.

  10. Gap-junction coupling and ATP-sensitive potassium channels in human β -cell clusters: Effects on emergent dynamics

    Science.gov (United States)

    Loppini, A.; Pedersen, M. G.; Braun, M.; Filippi, S.

    2017-09-01

    The importance of gap-junction coupling between β cells in pancreatic islets is well established in mouse. Such ultrastructural connections synchronize cellular activity, confine biological heterogeneity, and enhance insulin pulsatility. Dysfunction of coupling has been associated with diabetes and altered β -cell function. However, the role of gap junctions between human β cells is still largely unexplored. By using patch-clamp recordings of β cells from human donors, we previously estimated electrical properties of these channels by mathematical modeling of pairs of human β cells. In this work we revise our estimate by modeling triplet configurations and larger heterogeneous clusters. We find that a coupling conductance in the range 0.005 -0.020 nS/pF can reproduce experiments in almost all the simulated arrangements. We finally explore the consequence of gap-junction coupling of this magnitude between β cells with mutant variants of the ATP-sensitive potassium channels involved in some metabolic disorders and diabetic conditions, translating studies performed on rodents to the human case. Our results are finally discussed from the perspective of therapeutic strategies. In summary, modeling of more realistic clusters with more than two β cells slightly lowers our previous estimate of gap-junction conductance and gives rise to patterns that more closely resemble experimental traces.

  11. Effect of Mefloquine, a Gap Junction Blocker, on Circadian Period2 Gene Oscillation in the Mouse Suprachiasmatic Nucleus

    Directory of Open Access Journals (Sweden)

    Jinmi Koo

    2015-09-01

    Full Text Available BackgroundIn mammals, the master circadian pacemaker is localized in an area of the ventral hypothalamus known as the suprachiasmatic nucleus (SCN. Previous studies have shown that pacemaker neurons in the SCN are highly coupled to one another, and this coupling is crucial for intrinsic self-sustainability of the SCN central clock, which is distinguished from peripheral oscillators. One plausible mechanism underlying the intercellular communication may involve direct electrical connections mediated by gap junctions.MethodsWe examined the effect of mefloquine, a neuronal gap junction blocker, on circadian Period 2 (Per2 gene oscillation in SCN slice cultures prepared from Per2::luciferase (PER2::LUC knock-in mice using a real-time bioluminescence measurement system.ResultsAdministration of mefloquine causes instability in the pulse period and a slight reduction of amplitude in cyclic PER2::LUC expression. Blockade of gap junctions uncouples PER2::LUC-expressing cells, in terms of phase transition, which weakens synchrony among individual cellular rhythms.ConclusionThese findings suggest that neuronal gap junctions play an important role in synchronizing the central pacemaker neurons and contribute to the distinct self-sustainability of the SCN master clock.

  12. High Tc Josephson Junctions, SQUIDs and magnetometers

    International Nuclear Information System (INIS)

    Clarke, J.

    1991-01-01

    There has recently been considerable progress in the state-of-the-art of high-T c magnetometers based on dc SQUIDs (Superconducting Quantum Interference Devices). This progress is due partly to the development of more manufacturable Josephson junctions, making SQUIDs easier to fabricate, and partly to the development of multiturn flux transformers that convert the high sensitivity of SQUIDs to magnetic flux to a correspondingly high sensitivity to magnetic field. Needless to say, today's high-T c SQUIDs are still considerably less sensitive than their low-T c counterparts, particularly at low frequencies (f) where their level of 1/f noise remains high. Nonetheless, the performance of the high-T c devices has now reached the point where they are adequate for a number of the less demanding applications; furthermore, as we shall see, at least modest improvements in performance are expected in the near future. In this article, the author outlines these various developments. This is far from a comprehensive review of the field, however, and, apart from Sec. 2, he describes largely his own work. He begins in Sec. 2 with an overview of the various types of Josephson junctions that have been investigated, and in Sec. 3, he describes some of the SQUIDs that have been tested, and assess their performance. Section 4 discuss the development of the multilayer structures essential for an interconnect technology, and, in particular, for crossovers and vias. Section 5 shows how this technology enables one to fabricate multiturn flux transformers which, in turn, can be coupled to SQUIDs to make magnetometers. The performance and possible future improvements in these magnetometers are assessed, and some applications mentioned

  13. Intercellular coupling mediated by potassium accumulation in peg-and-socket junctions

    DEFF Research Database (Denmark)

    Vigmond, Edward J.; Bardakjian, Berj L.; Thuneberg, Lars

    2000-01-01

    Physiology, peg-and-socket junctions, smooth muscle, boundary element method, coupling, morphology......Physiology, peg-and-socket junctions, smooth muscle, boundary element method, coupling, morphology...

  14. Handbook of networking & connectivity

    CERN Document Server

    McClain, Gary R

    1994-01-01

    Handbook of Networking & Connectivity focuses on connectivity standards in use, including hardware and software options. The book serves as a guide for solving specific problems that arise in designing and maintaining organizational networks.The selection first tackles open systems interconnection, guide to digital communications, and implementing TCP/IP in an SNA environment. Discussions focus on elimination of the SNA backbone, routing SNA over internets, connectionless versus connection-oriented networks, internet concepts, application program interfaces, basic principles of layering, proto

  15. The Connected Traveler

    Energy Technology Data Exchange (ETDEWEB)

    Young, Stanley

    2017-04-24

    The Connected Traveler project is a multi-disciplinary undertaking that seeks to validate potential for transformative transportation system energy savings by incentivizing energy efficient travel behavior.

  16. Association of visceral adiposity with oesophageal and junctional adenocarcinomas.

    LENUS (Irish Health Repository)

    Beddy, P

    2012-02-01

    BACKGROUND: Obesity is associated with an increased incidence of oesophageal and oesophagogastric junction adenocarcinoma, in particular Siewert types I and II. This study compared abdominal fat composition in patients with oesophageal\\/junctional adenocarcinoma with that in patients with oesophageal squamous cell carcinoma and gastric adenocarcinoma, and in controls. METHOD: In total, 194 patients (110 with oesophageal\\/junctional adenocarcinoma, 38 with gastric adenocarcinoma and 46 with oesophageal squamous cell carcinoma) and 90 matched control subjects were recruited. The abdominal fat area was assessed using computed tomography (CT), and the total fat area (TFA), visceral fat area (VFA) and subcutaneous fat area (SFA) were calculated. RESULTS: Patients with oesophageal\\/junctional adenocarcinoma had significantly higher TFA and VFA values compared with controls (both P < 0.001), patients with gastric adenocarcinoma (P = 0.013 and P = 0.006 respectively) and patients with oesophageal squamous cell carcinoma (both P < 0.001). For junctional tumours, the highest TFA and VFA values were seen in patients with Siewert type I tumours (respectively P = 0.041 and P = 0.033 versus type III; P = 0.332 and P = 0.152 versus type II). CONCLUSION: Patients with oesophageal\\/junctional adenocarcinoma, in particular oesophageal and Siewert type I junctional tumours, have greater CT-defined visceral adiposity than patients with gastric adenocarcinoma or oesophageal squamous cell carcinoma, or controls.

  17. Reduced resistance drift in tunnel junctions using confined tunnel barriers

    Science.gov (United States)

    Barcikowski, Z. S.; Pomeroy, J. M.

    2017-11-01

    Metal-insulator-metal (MIM) tunnel junctions with the aluminum oxide tunnel barriers confined between cobalt electrodes exhibit less resistance drift over time than junctions that utilize a thick, unconfined aluminum electrode. The improved long time stability is attributed to better initial oxide quality achieved through confinement (use of a potential energy well for the oxygen) and plasma oxidation. In this work, Co/AlOx/Co and Co/Al/AlOx/Co tunnel junction aging is compared over a period of approximately 9 months using transport measurements and Wentzel-Kramers-Brillouin (WKB) based modelling. The Co/AlOx/Co (confined) tunnel junction resistance increased by (32 ± 6) % over 5400 h, while Co/Al/AlOx/Co (unconfined) tunnel junction resistance increased by (85 ± 23) % over 5200 h. Fit parameters for the tunnel barrier width and potential energy barriers were extracted using WKB transport modelling. These values change only a small amount in the confined Co/AlOx/Co tunnel junction but show a significant drift in the unconfined Co/AlOx/Co tunnel junction.

  18. Solar cell junction temperature measurement of PV module

    KAUST Repository

    Huang, B.J.

    2011-02-01

    The present study develops a simple non-destructive method to measure the solar cell junction temperature of PV module. The PV module was put in the environmental chamber with precise temperature control to keep the solar PV module as well as the cell junction in thermal equilibrium with the chamber. The open-circuit voltage of PV module Voc is then measured using a short pulse of solar irradiation provided by a solar simulator. Repeating the measurements at different environment temperature (40-80°C) and solar irradiation S (200-1000W/m2), the correlation between the open-circuit voltage Voc, the junction temperature Tj, and solar irradiation S is derived.The fundamental correlation of the PV module is utilized for on-site monitoring of solar cell junction temperature using the measured Voc and S at a short time instant with open circuit. The junction temperature Tj is then determined using the measured S and Voc through the fundamental correlation. The outdoor test results show that the junction temperature measured using the present method, Tjo, is more accurate. The maximum error using the average surface temperature Tave as the junction temperature is 4.8 °C underestimation; while the maximum error using the present method is 1.3 °C underestimation. © 2010 Elsevier Ltd.

  19. A transistor based on 2D material and silicon junction

    Science.gov (United States)

    Kim, Sanghoek; Lee, Seunghyun

    2017-07-01

    A new type of graphene-silicon junction transistor based on bipolar charge-carrier injection was designed and investigated. In contrast to many recent studies on graphene field-effect transistor (FET), this device is a new type of bipolar junction transistor (BJT). The transistor fully utilizes the Fermi level tunability of graphene under bias to increase the minority-carrier injection efficiency of the base-emitter junction in the BJT. Single-layer graphene was used to form the emitter and the collector, and a p-type silicon was used as the base. The output of this transistor was compared with a metal-silicon junction transistor ( i.e. surface-barrier transistor) to understand the difference between a graphene-silicon junction and metal-silicon Schottky junction. A significantly higher current gain was observed in the graphene-silicon junction transistor as the base current was increased. The graphene-semiconductor heterojunction transistor offers several unique advantages, such as an extremely thin device profile, a low-temperature (transistor current gain ( β) of 33.7 and a common-emitter amplifier voltage gain of 24.9 were achieved.

  20. Ileocolic junction resection in dogs and cats: 18 cases.

    Science.gov (United States)

    Fernandez, Yordan; Seth, Mayank; Murgia, Daniela; Puig, Jordi

    2017-12-01

    There is limited veterinary literature about dogs or cats with ileocolic junction resection and its long-term follow-up. To evaluate the long-term outcome in a cohort of dogs and cats that underwent resection of the ileocolic junction without extensive (≥50%) small or large bowel resection. Medical records of dogs and cats that had the ileocolic junction resected were reviewed. Follow-up information was obtained either by telephone interview or e-mail correspondence with the referring veterinary surgeons. Nine dogs and nine cats were included. The most common cause of ileocolic junction resection was intussusception in dogs (5/9) and neoplasia in cats (6/9). Two dogs with ileocolic junction lymphoma died postoperatively. Only 2 of 15 animals, for which long-term follow-up information was available, had soft stools. However, three dogs with suspected chronic enteropathy required long-term treatment with hypoallergenic diets alone or in combination with medical treatment to avoid the development of diarrhoea. Four of 6 cats with ileocolic junction neoplasia were euthanised as a consequence of progressive disease. Dogs and cats undergoing ileocolic junction resection and surviving the perioperative period may have a good long-term outcome with mild or absent clinical signs but long-term medical management may be required.

  1. Advance of Mechanically Controllable Break Junction for Molecular Electronics.

    Science.gov (United States)

    Wang, Lu; Wang, Ling; Zhang, Lei; Xiang, Dong

    2017-06-01

    Molecular electronics stands for the ultimate size of functional elements, keeping up with an unstoppable trend over the past few decades. As a vital component of molecular electronics, single molecular junctions have attracted significant attention from research groups all over the world. Due to its pronounced superiority, the mechanically controllable break junctions (MCBJ) technique has been widely applied to characterize the dynamic performance of single molecular junctions. This review presents a system analysis for single-molecule junctions and offers an overview of four test-beds for single-molecule junctions, thus offering more insight into the mechanisms of electron transport. We mainly focus on the development of state-of-the-art mechanically controlled break junctions. The three-terminal gated MCBJ approaches are introduced to manipulate the electron transport of molecules, and MCBJs are combined with characterization techniques. Additionally, applications of MCBJs and remarkable properties of single molecules are addressed. Finally, the challenges and perspective for the mechanically controllable break junctions technique are provided.

  2. Flicker (1/f) noise in tunnel junction DC SQUIDS

    International Nuclear Information System (INIS)

    Koch, R.H.; Clarke, J.; Goubau, W.M.; Martinis, J.M.; Pegrum, C.M.; Van Harlingen, D.J.

    1983-01-01

    We have measured the spectral density of the 1/f voltage noise in current-biased resistively shunted Josephson tunnel junctions and dc SQUIDs. A theory in which fluctuations in the temperature give rise to fluctuations in the critical current and hence in the voltage predicts the magnitude of the noise quite accurately for junctions with areas of about 2 x 10 4 μm 2 , but significantly overestimates the noise for junctions with areas of about 6 μm 2 . DC SQUIDs fabricated from these two types of junctions exhibit substantially more 1/f voltage noise than would be predicted from a model in which the noise arises from critical current fluctuations in the junctions. This result was confirmed by an experiment involving two different bias current and flux modulation schemes, which demonstrated that the predominant 1/f voltage noise arises not from critical current fluctuations, but from some unknown source that can be regarded as an apparent 1/f flux noise. Measurements on five different configurations of dc SQUIDs fabricated with thin-film tunnel junctions and with widely varying areas, inductances, and junction capacitances show that the spectral density of the 1/f equivalent flux noise is roughtly constant, within a factor of three of (10 -10 /f)phi 2 0 Hz -1 . It is emphasized that 1/f flux noise may not be the predominant source of 1/f noise in SQUIDS fabricated with other technologies

  3. Building a Six-Junction Inverted Metamorphic Concentrator Solar Cell

    Energy Technology Data Exchange (ETDEWEB)

    Geisz, John F [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Steiner, Myles A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Jain, Nikhil [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Schulte, Kevin L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); France, Ryan M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); McMahon, William E [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Perl, Emmett [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Friedman, Daniel J [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-12-02

    We propose practical six-junction (6J) inverted metamorphic multijunction (IMM) concentrator solar cell designs with the potential to exceed 50% efficiency using moderately high quality junction materials. We demonstrate the top three junctions and their monolithic integration lattice matched to GaAs using 2.1-eV AlGaInP, 1.7-eV AlGaAs or GaInAsP, and 1.4-eV GaAs with external radiative efficiencies >0.1%. We demonstrate tunnel junctions with peak tunneling current >400 A/cm2 that are transparent to <2.1-eV light. We compare the bottom three GaInAs(p) junctions with bandgaps of 1.2, 1.0, and 0.7 eV grown on InP and transparent metamorphic grades with low dislocation densities. The solution to an integration challenge resulting from Zn diffusion in the GaAs junction is illustrated in a five-junction IMM. Excellent 1-sun performance is demonstrated in a complete 6J IMM device with VOC = 5.15 V, and a promising pathway toward >50% efficiency at high concentrations is presented.

  4. Electron-beam damaged high-temperature superconductor Josephson junctions

    International Nuclear Information System (INIS)

    Pauza, A.J.; Booij, W.E.; Herrmann, K.; Moore, D.F.; Blamire, M.G.; Rudman, D.A.; Vale, L.R.

    1997-01-01

    Results are presented on the fabrication and characterization of high critical temperature Josephson junctions in thin films of YBa 2 Cu 3 O 7-δ produced by the process of focused electron-beam irradiation using 350 keV electrons. The junctions so produced have uniform spatial current densities, can be described in terms of the resistive shunted junction model, and their current densities can be tailored for a given operating temperature. The physical properties of the damaged barrier can be described as a superconducting material of either reduced or zero critical temperature (T c ), which has a length of ∼15nm. The T c reduction is caused primarily by oxygen Frenkel defects in the Cu - O planes. The large beam currents used in the fabrication of the junctions mean that the extent of the barrier is limited by the incident electron-beam diameter, rather than by scattering within the film. The properties of the barrier can be calculated using a superconductor/normal/superconductor (SNS) junction model with no boundary resistance. From the SNS model, we can predict the scaling of the critical current resistance (I c R n ) product and gain insight into the factors controlling the junction properties, T c , and reproducibility. From the measured I c R n scaling data, we can predict the I c R n product of a junction at a given operating temperature with a given current density. I c R n products of ∼2mV can be achieved at 4.2 K. The reproducibility of several junctions in a number of samples can be characterized by the ratio of the maximum-to-minimum critical currents on the same substrate of less than 1.4. Stability over several months has been demonstrated at room and refrigerator temperatures (297 and 281 K) for junctions that have been initially over damaged and then annealed at temperatures ∼380K. (Abstract Truncated)

  5. The cranial-spinal junction in medulloblastoma: does it matter?

    International Nuclear Information System (INIS)

    Narayana, Ashwatha; Jeswani, Sam; Paulino, Arnold C.

    1999-01-01

    Purpose: Late effects of treatment in children and young adults with medulloblastoma can be influenced by the technique employed in radiating the craniospinal axis. The purpose of this study is to determine whether the placement of the cranial-spinal junction has an impact on dose to the cervical spinal cord and surrounding organs. Methods and Materials: Five patients underwent computed tomography (CT) simulation in the prone position for craniospinal irradiation. A dose of 36 Gy was prescribed to the entire neuraxis. The doses to the cervical spinal cord and surrounding organs were calculated using a cranial-spinal junction at the C1-C2 vertebral interspace (high junction) or at the lowest point in the neck, with exclusion of the shoulders in the lateral cranial fields (low junction).The volume of critical organs at risk, as well as dose to these structures using the cranial and spinal field(s) were outlined and calculated using the CMS FOCUS 3-dimensional treatment planning system. Results: The average dose to the cervical spinal cord was 11.9% higher than the prescribed dose with the low junction, and 6.7% higher with the high junction. However, doses to the thyroid gland, mandible, pharynx, and larynx were increased by an average of 29.6%, 75.8%, 70.6%, and 227.7%, respectively, by the use of the high junction compared to the low junction. Conclusion: A higher dose to the cervical spinal cord can be minimized by using a high junction. However, this would be at the cost of substantially increased doses to surrounding organs such as the thyroid gland, mandible, pharynx, and larynx. This can be critical in children and young adults, where hypothyroidism, mandibular hypoplasia, and development of second malignancies may be a late sequela of radiation therapy

  6. Steady-state properties of Josephson junctions with direct conductivity

    International Nuclear Information System (INIS)

    Zubkov, A.A.; Kupriyanov, M.Y.; Semenov, V.K.

    1981-01-01

    A new criterion for determining the kinetic inductance of Josephson junctions is introduced. The effects of temperature T, the critical temperatures of the superconducting electrodes T/sub c/1 and T/sub c/2, and the weak-link length on the kinetic inductance of ''dirty'' junctions with direct conductivity are analyzed within the framework of the Usadel equations. Numerical calculations show that both a large characteristic voltage and a nearly harmonic dependence of the current on the phase difference of the superconducting-electrode wave functions cannot be obtained by varying the junction parameters

  7. Temporal correlations and structural memory effects in break junction measurements

    DEFF Research Database (Denmark)

    Magyarkuti, A.; Lauritzen, Kasper Primdal; Balogh, Zoltan Imre

    2017-01-01

    that correlations between the opening and subsequent closing traces may indicate structural memory effects in atomic-sized metallic and molecular junctions. Applying these methods on measured and simulated gold metallic contacts as a test system, we show that the surface diffusion induced flattening of the broken......-molecule junctions, we demonstrate pronounced contact memory effects and recovery of the molecule for junctions breaking before atomic chains are formed. However, if chains are pulled the random relaxation of the chain and molecule after rupture prevents opening-closing correlations....

  8. Internal resonances in periodically modulated long Josephson junctions

    DEFF Research Database (Denmark)

    Larsen, Britt Hvolbæk; Mygind, Jesper; Ustinov, Alexey V.

    1995-01-01

    Current-voltage (I-V) characteristics of long Josephson junctions with a periodic lattice of localized inhomogeneities are studied. The interaction between the moving fluxons and the inhomogeneities causes resonant steps in the IV-curve. Some of these steps are due to a synchronization to resonant...... Fiske modes in the sub-junctions formed between the inhomogeneities. The voltage positions of the resonant steps oscillate as function of the applied magnetic field with a period corresponding to the inclusion of one magnetic flux quantum, Φ0=h/2e, per sub-junction. A qualitative explanation that takes...

  9. Guidance of matter waves through Y-junctions

    Energy Technology Data Exchange (ETDEWEB)

    Kevrekidis, P.G.; Frantzeskakis, D.J.; Theocharis, G.; Kevrekidis, I.G

    2003-10-27

    We discuss the concept of Y-junctions for matter waves and investigate their guidance properties, focusing on the case of Bose-Einstein condensates with attractive interatomic interactions. We examine both discrete and continuous models, respectively relevant to Y-junctions formed in optical lattices (OL) and magnetic traps (MT). We find a strong dependence of the transmitted fraction of the condensate (in the OL case) on the angle with a maximum (per arm) of approximately 30%. In the MT case, we show that the presence of the junction's wedge can prevent collapse of the original condensate.

  10. Superconducting proximity effect in mesoscopic superconductor/normal-metal junctions

    CERN Document Server

    Takayanagi, H; Toyoda, E

    1999-01-01

    The superconducting proximity effect is discussed in mesoscopic superconductor/normal-metal junctions. The newly-developed theory shows long-range phase-coherent effect which explaines early experimental results of giant magnetoresistance oscillations in an Andreev interferometer. The theory also shows that the proximity correction to the conductance (PCC) has a reentrant behavior as a function of energy. The reentrant behavior is systematically studied in a gated superconductor-semiconductor junction. A negative PCC is observed in the case of a weak coupling between the normal metal and the external reservoir. Phase coherent ac effect is also observed when rf is irradiated to the junction.

  11. Externally pumped millimeter-wave Josephson-junction parametric amplifier

    DEFF Research Database (Denmark)

    Levinsen, M.T; Pedersen, Niels Falsig; Sørensen, Ole

    1980-01-01

    A unified theory of the singly and doubly degenerate Josephson-junction parametric amplifier is presented. Experiments with single junctions on both amplifier modes at frequencies 10, 35, and 70 GHz are discussed. Low-noise temperature (∼100 K, single sideband (SSB)) and reasonable gain (∼8 d......B) were obtained at 35 GHz in the singly degenerate mode. On the basis of the theory and experiments, a general procedure for optimizing junction parameters is discussed and illustrated by the specific design of a 100-GHz amplifier....

  12. Two new septate junctions in the phylum Coelenterata.

    Science.gov (United States)

    Green, C R; Flower, N E

    1980-04-01

    Freeze-fracture of fixed and unfixed tissue, lanthanum tracer and conventional thin-section studies have revealed 2 new types of septate junction in the class Anthozoa, phylum Coelenterata. These new junctions have the 15-18-nm intercellular spacing of all other described septate junctions and are found around the apical circumference of cells lining a lumen or outside edge. However, in freeze-fracture replicas and tangential views of lanthanum-impregnated tissue, they are seen to be quite different from other known septate junction types. One of the new junctions is found in endothelial tissue such as that lining the gut or the inside of the tentacles. In tangential view it is seen to consist of relatively short, straight, double septa, again with lateral projections. In feeeze-fracture of unfixed tissue, the junction consists of double rows of particles on the P face, the particles of one row being rounded, those of the other being elongated at right angles to the line of the septum. This dichotomy in particle size is unexpected, as the 2 halves of the septa as seen in tangential view are symmetrical. In freeze-fracture of fixed material the particle arrays remain on the P face and appear similar to those of unfixed material, but never as clear. In fixed tissue, some distortion had occurred and in extreme cases septa appear as a single broad jumbled row of particles. In this double septa junction, the rows of particles seen in freeze-fracture are occasionally seen to anastomose with a septum dividing into 2 and a third row of particles aligning with the 2 new septa to form their double particle rows. In both fixed and unfixed tissues, the E face of the junction consists of wide, shallow grooves. The second of the new junctions occurs in epithelial tissue, such as around the outer edge of sea-anemone tentacles, and consists of long wavy septa with lateral projections. In views where these projections appear longest, they arise predominantly from one side of the

  13. Fluxon propagation and Fiske steps in long Josephson tunnel junctions

    DEFF Research Database (Denmark)

    Erné, S. N.; Ferrigno, A.; Parmentier, R. D.

    1983-01-01

    The dynamical behavior of fluxons propagating in the presence of an applied magnetic field on an overlap-geometry Josephson tunnel junction of length 5λJ having a McCumber βc=5π is studied by numerical integration of the circuit equations of a 50-section lumped RSJ-type (resistive shunted junction......) model. Resonant propagating configurations corresponding to the first and third Fiske steps are found. The fundamental frequencies and power levels of the radiation emitted from one end when the junction is biased on the first and third Fiske steps and on the first zero-field step are comparable...

  14. Simulation of Collective Excitations in Long Josephson Junction Stacks

    Science.gov (United States)

    Rahmonov, Ilhom; Shukrinov, Yury; Atanasova, Pavlina; Zemlyanaya, Elena; Streltsova, Oksana; Zuev, Maxim; Plecenik, Andrej; Irie, Akinobu

    2018-02-01

    The phase dynamics of a stack of long Josephson junctions has been studied. Both inductive and capacitive couplings between Josephson junctions have been taken into account in the calculations. The IV-curve, the dependence on the bias current of the radiation power and dynamics of each JJs of the stack have been investigated. The coexistence of the charge traveling wave and fluxon states has been observed. This state can be considered as a new collective excitation in the system of coupled Josephson junctions. We demonstrate that the observed collective excitation leads to the decrease of radiation power from the system.

  15. Archives: Mathematics Connection

    African Journals Online (AJOL)

    Items 1 - 9 of 9 ... Archives: Mathematics Connection. Journal Home > Archives: Mathematics Connection. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives. 1 - 9 of 9 Items. 2011 ...

  16. Connecting to the internet.

    Science.gov (United States)

    Downes, P K

    2007-03-24

    There are many and varied ways of connecting to the Internet. For the vast majority of the Internet's existence, most people connected using the maddeningly slow click-and-wait experience of a dial-up connection. By June 2005, the number of the newer and faster broadband connections in the UK exceeded dial-up connections for the first time (approximately 1/3 broadband cable and 2/3 broadband ADSL). By the middle of 2006, 40% of households in the UK had a broadband connection, compared to just 28% in 2005. In the last quarter of 2006, the total number of broadband subscriptions in the UK had topped the 13 million mark (one subscriber may equate to multiple users sharing one connection). Mobile Internet access via mobile phones and other devices will mark the biggest change in the way that we access the Internet and is likely to have a profound effect on our everyday lives. In this section, we look at the various ways of connecting to the Internet and compare the features, benefits and costs of each.

  17. Handbook of Brain Connectivity

    CERN Document Server

    Jirsa, Viktor K

    2007-01-01

    Our contemporary understanding of brain function is deeply rooted in the ideas of the nonlinear dynamics of distributed networks. Cognition and motor coordination seem to arise from the interactions of local neuronal networks, which themselves are connected in large scales across the entire brain. The spatial architectures between various scales inevitably influence the dynamics of the brain and thereby its function. But how can we integrate brain connectivity amongst these structural and functional domains? Our Handbook provides an account of the current knowledge on the measurement, analysis and theory of the anatomical and functional connectivity of the brain. All contributors are leading experts in various fields concerning structural and functional brain connectivity. In the first part of the Handbook, the chapters focus on an introduction and discussion of the principles underlying connected neural systems. The second part introduces the currently available non-invasive technologies for measuring struct...

  18. Modeling Structural Brain Connectivity

    DEFF Research Database (Denmark)

    Ambrosen, Karen Marie Sandø

    The human brain consists of a gigantic complex network of interconnected neurons. Together all these connections determine who we are, how we react and how we interpret the world. Knowledge about how the brain is connected can further our understanding of the brain’s structural organization, help...... improve diagnosis, and potentially allow better treatment of a wide range of neurological disorders. Tractography based on diffusion magnetic resonance imaging is a unique tool to estimate this “structural connectivity” of the brain non-invasively and in vivo. During the last decade, brain connectivity...... has increasingly been analyzed using graph theoretic measures adopted from network science and this characterization of the brain’s structural connectivity has been shown to be useful for the classification of populations, such as healthy and diseased subjects. The structural connectivity of the brain...

  19. Generalized connectivity of graphs

    CERN Document Server

    Li, Xueliang

    2016-01-01

    Noteworthy results, proof techniques, open problems and conjectures in generalized (edge-) connectivity are discussed in this book. Both theoretical and practical analyses for generalized (edge-) connectivity of graphs are provided. Topics covered in this book include: generalized (edge-) connectivity of graph classes, algorithms, computational complexity, sharp bounds, Nordhaus-Gaddum-type results, maximum generalized local connectivity, extremal problems, random graphs, multigraphs, relations with the Steiner tree packing problem and generalizations of connectivity. This book enables graduate students to understand and master a segment of graph theory and combinatorial optimization. Researchers in graph theory, combinatorics, combinatorial optimization, probability, computer science, discrete algorithms, complexity analysis, network design, and the information transferring models will find this book useful in their studies.

  20. Aeroacoustics of T-junction merging flow.

    Science.gov (United States)

    Lam, G C Y; Leung, R C K; Tang, S K

    2013-02-01

    This paper reports a numerical study of the aeroacoustics of merging flow at T-junction. The primary focus is to elucidate the acoustic generation by the flow unsteadiness. The study is conducted by performing direct aeroacoustic simulation approach, which solves the unsteady compressible Navier-Stokes equations and the perfect gas equation of state simultaneously using the conservation element and solution element method. For practical flows, the Reynolds number based on duct width is usually quite high (>10(5)). In order to properly account for the effects of flow turbulence, a large eddy simulation methodology together with a wall modeling derived from the classical logarithm wall law is adopted. The numerical simulations are performed in two dimensions and the acoustic generation physics at different ratios of side-branch to main duct flow velocities VR (=0.5,0.67,1.0,2.0) are studied. Both the levels of unsteady interactions of merging flow structures and the efficiency of acoustic generation are observed to increase with VR. Based on Curle's analogy, the major acoustic source is found to be the fluctuating wall pressure induced by the flow unsteadiness occurred in the downstream branch. A scaling between the wall fluctuating force and the efficiency of the acoustic generation is also derived.

  1. Towards quantum signatures in a swept-bias Josephson junction

    Energy Technology Data Exchange (ETDEWEB)

    Losert, Harald; Vogel, Karl; Schleich, Wolfgang P. [Institut fuer Quantenphysik and Center for Integrated Quantum Science and Technology (IQST), Universitaet Ulm, D-89069 Ulm (Germany)

    2016-07-01

    Josephson junctions are one of the best examples for the observation of macroscopic quantum tunneling. The phase difference in a current-biased Josephson junction behaves like the position of a particle in a tilted washboard potential. The escape of this phase-particle corresponds to the voltage switching of the associated junction. Quantum mechanically, the escape from the washboard potential can be explained as tunneling from the ground state, or an excited state. However, it has been shown, that in the case of periodic driving the experimental data for quantum mechanical key features, e.g. Rabi oscillations or energy level quantization, can be reproduced by a completely classical description. Motivated by this discussion, we investigate a swept-bias Josephson junction in the case of a large critical current. In particular, we contrast the switching current distributions resulting from a quantum mechanical and classical description of the time evolution.

  2. Fabrication of shuttle-junctions for nanomechanical transfer of electrons

    Energy Technology Data Exchange (ETDEWEB)

    Moskalenko, A V; Gordeev, S N [Department of Physics, University of Bath, Claverton Down Road, Bath BA2 7AS (United Kingdom); Koentjoro, O F; Raithby, P R; French, R W; Marken, F [Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AS (United Kingdom); Savel' ev, S, E-mail: A.Moskalenko@bath.ac.u [Department of Physics, Loughborough University, Loughborough LE11 3TU (United Kingdom)

    2009-12-02

    We report on the fabrication of nanomechanical devices for shuttling of electrons from one electrode to another. Each device consists of a 20 nm diameter gold nanoparticle embedded within the gap between two gold electrodes. In two different kinds of shuttle-junctions the nanoparticle is attached to the electrodes through either (i) a single layer of 1,8-octanedithiol or (ii) a multilayer of 1-octanethiol molecules. The thiol layers play the role of 'damped springs', such that when a sufficient voltage bias is applied to the junction, the nanoparticle is expected to start oscillating and thereby transferring electrons from one electrode to the other. For both kinds of shuttle-junctions we observed an abrupt increase in the transmitted current above a threshold voltage, which can be attributed to a transition from the stationary to the oscillating regime. The threshold voltage was found to be lower for single-layer shuttle-junctions.

  3. Magnetoanisotropic Andreev reflection in ferromagnet-superconductor junctions.

    Science.gov (United States)

    Högl, Petra; Matos-Abiague, Alex; Žutić, Igor; Fabian, Jaroslav

    2015-09-11

    Andreev reflection spectroscopy of ferromagnet-superconductor (FS) junctions [corrected] is an important probe of spin polarization. We theoretically investigate spin-polarized transport in FS junctions in the presence of Rashba and Dresselhaus interfacial spin-orbit fields and show that Andreev reflection can be controlled by changing the magnetization orientation. We predict a giant in- and out-of-plane magnetoanisotropy of the junction conductance. If the ferromagnet is highly spin polarized-in the half-metal limit-the magnetoanisotropic Andreev reflection depends universally on the spin-orbit fields only. Our results show that Andreev reflection spectroscopy can be used for sensitive probing of interfacial spin-orbit fields in a FS junction.

  4. Systematic optimization of quantum junction colloidal quantum dot solar cells

    KAUST Repository

    Liu, Huan

    2012-01-01

    The recently reported quantum junction architecture represents a promising approach to building a rectifying photovoltaic device that employs colloidal quantum dot layers on each side of the p-n junction. Here, we report an optimized quantum junction solar cell that leverages an improved aluminum zinc oxide electrode for a stable contact to the n-side of the quantum junction and silver doping of the p-layer that greatly enhances the photocurrent by expanding the depletion region in the n-side of the device. These improvements result in greater stability and a power conversion efficiency of 6.1 under AM1.5 simulated solar illumination. © 2012 American Institute of Physics.

  5. BPS dynamics of the triple (p,q) string junction

    International Nuclear Information System (INIS)

    Rey, S.-J.; Yee, J.-T.

    1998-01-01

    We study the dynamics of the triple junction of (p,q) strings in type IIB string theory. We probe the tension and mass density of (p,q) strings by studying harmonic fluctuations of the triple junction. We show that they agree perfectly with the BPS formula provided a suitable geometric interpretation of the junction is given. We provide a precise statement of the BPS limit and force-balance property. At weak coupling and sufficiently dense limit, we argue that a (p,q) string embedded in the string network is a 'wiggly string', whose low-energy dynamics can be described via a renormalization group evolved, smooth effective non-relativistic string. We also suggest the possibility that, upon type IIB strings being promoted to the M-theory membrane, there can exist 'evanescent' bound-states at the triple junction in the continuum. (orig.)

  6. Development of High Temperature Superconducting Josephson Junction Device Technology

    National Research Council Canada - National Science Library

    Myers, Kirsten

    1998-01-01

    The DuPont program was successful in generating useful knowledge about thallium cuprate materials, photoresist reflow processing, and radiant heater technology though it did not lead to a new junction technology...

  7. Magnetic domain wall engineering in a nanoscale permalloy junction

    Science.gov (United States)

    Wang, Junlin; Zhang, Xichao; Lu, Xianyang; Zhang, Jason; Yan, Yu; Ling, Hua; Wu, Jing; Zhou, Yan; Xu, Yongbing

    2017-08-01

    Nanoscale magnetic junctions provide a useful approach to act as building blocks for magnetoresistive random access memories (MRAM), where one of the key issues is to control the magnetic domain configuration. Here, we study the domain structure and the magnetic switching in the Permalloy (Fe20Ni80) nanoscale magnetic junctions with different thicknesses by using micromagnetic simulations. It is found that both the 90-° and 45-° domain walls can be formed between the junctions and the wire arms depending on the thickness of the device. The magnetic switching fields show distinct thickness dependencies with a broad peak varying from 7 nm to 22 nm depending on the junction sizes, and the large magnetic switching fields favor the stability of the MRAM operation.

  8. Photonic and Quantum Interactions of Atomic-Scale Junctions

    Data.gov (United States)

    National Aeronautics and Space Administration — In this proposal, the fundamental quantum and photonic interactions of bimetallic atomic-scale junctions (ASJs) will be explored, with three major space...

  9. Perspective: Theory of quantum transport in molecular junctions

    Science.gov (United States)

    Thoss, Michael; Evers, Ferdinand

    2018-01-01

    Molecular junctions, where single molecules are bound to metal or semiconductor electrodes, represent a unique architecture to investigate molecules in a distinct nonequilibrium situation and, in a broader context, to study basic mechanisms of charge and energy transport in a many-body quantum system at the nanoscale. Experimental studies of molecular junctions have revealed a wealth of interesting transport phenomena, the understanding of which necessitates theoretical modeling. The accurate theoretical description of quantum transport in molecular junctions is challenging because it requires methods that are capable to describe the electronic structure and dynamics of molecules in a condensed phase environment out of equilibrium, in some cases with strong electron-electron and/or electronic-vibrational interaction. This perspective discusses recent progress in the theory and simulation of quantum transport in molecular junctions. Furthermore, challenges are identified, which appear crucial to achieve a comprehensive and quantitative understanding of transport in these systems.

  10. Low-Cost Multi-Junction Photovoltaic Cells, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed SBIR project will provide a pathway to dramatically reduce the cost of multi-junction solar cells. The project leverages a TRL6 micropackaging process...

  11. Perspective: Thermal and thermoelectric transport in molecular junctions

    Science.gov (United States)

    Cui, Longji; Miao, Ruijiao; Jiang, Chang; Meyhofer, Edgar; Reddy, Pramod

    2017-03-01

    With the advent of molecular electronics, tremendous attention has been paid towards understanding the structure-function relationship of molecular junctions. Understanding how heat is transported, dissipated, and converted into electricity in molecular junctions is of great importance for designing thermally robust molecular circuits and high-performance energy conversion devices. Further, the study of thermal and thermoelectric phenomena in molecular junctions provides novel insights into the limits of applicability of classical laws. Here, we present a review of the computational and experimental progress made in probing thermoelectric effects, thermal conduction, heat dissipation, and local heating/cooling in self-assembled monolayer and single molecule junctions. We also discuss some outstanding challenges and potential future directions.

  12. Status of Four-Junction Cell Development at Fraunhofer ISE

    Directory of Open Access Journals (Sweden)

    Lackner D.

    2017-01-01

    Full Text Available Four-junction solar cells are being developed for space applications as they promise higher efficiencies compared to the present GaInP/GaInAs/Ge triple-junction industry standard. There are multiple technological routes to achieve four-junction cells with the ideal bandgap combination of 1.9 eV, 1.4 eV 1.05 eV and 0.7 eV. This includes metamorphic growth concepts and direct semiconductor wafer bonded technology. All cell designs have their specific advantages and challenges. Therefore, at Fraunhofer ISE a plurality of different four-junction cell concepts is under investigation. The current status of the development and a discussion of so far achieved characteristics are presented in this work.

  13. Negative differential resistance in Josephson junctions coupled to a cavity

    DEFF Research Database (Denmark)

    Pedersen, Niels Falsig; Filatrella, G.; Pierro, V.

    2014-01-01

    Regions with negative differential resistance can arise in the IV curve of Josephson junctions and this phenomenon plays an essential role for applications, in particular for THz radiation emission. For the measurement of high frequency radiation from Josephson junctions, a cavity – either internal...... or external – is often used. A cavity may also induce a negative differential resistance region at the lower side of the resonance frequency. We investigate the dynamics of Josephson junctions with a negative differential resistance in the quasi particle tunnel current, i.e. in the McCumber curve. We find...... that very complicated and unexpected interactions take place. This may be useful for the interpretation of experimental measurements of THz radiation from intrinsic Josephson junctions....

  14. No junctional communication between epithelial cells in hydra

    DEFF Research Database (Denmark)

    de Laat, S W; Tertoolen, L G; Grimmelikhuijzen, C J

    1980-01-01

    Diffusion gradients of morphogens have been inferred as a basis for the control of morphogenesis in hydra, and morphogenetic substances have been found which, on the basis of their molecular weight (MW), should be able to pass gap junctions. There have been several reports of the presence of gap...... junctions between epithelial cells of hydra. However, until now, there has been no report published on whether these junctions enable the epithelial cells to exchange molecules of small molecular weight, as has been described in other organisms. Therefore we decided to investigate the communicative...... properties of the junctional membranes by electrophysiological methods and by intracellular-dye iontophoresis. We report here that no electrotonic coupling is detectable between epithelial cells of Hydra attenuata in: (1) intact animals, (2) head-regenerating animals, (3) cell re-aggregates, and (4) hydra...

  15. ALTERNATIVE MATERIALS FOR RAMP-EDGE SNS JUNCTIONS

    International Nuclear Information System (INIS)

    Jia, Q.; Fan, Y.; Gim, Y.

    1999-01-01

    We report on the processing optimization and fabrication of ramp-edge high-temperature superconducting junctions by using alternative materials for both superconductor electrodes and normal-metal barrier. By using Ag-doped YBa 2 Cu 3 O 7-x (Ag:YBCO) as electrodes and a cation-modified compound of (Pr y Gd 0.6-y )Ca 0.4 Ba 1.6 La 0.4 Cu 3 O 7 (y = 0.4, 0.5, and 0.6) as a normal-metal barrier, high-temperature superconducting Josephson junctions have been fabricated in a ramp-edge superconductor/normal-metal/superconductor (SNS) configuration. By using Ag:YBCO as electrodes, we have found that the processing controllability /reproducibility and the stability of the SNS junctions are improved substantially. The junctions fabricated with these alternative materials show well-defined RSJ-like current vs voltage characteristics at liquid nitrogen temperature

  16. High Density Planar High Temperature Superconducting Josephson Junctions Arrays

    National Research Council Canada - National Science Library

    Dynes, Robert C; Cybart, Shane

    2006-01-01

    .... We have found that a circuit fabrication technique pioneered in our lab during previous AFOSR funding periods can be used to fabricate arrays of junctions as well as superconducting interference devices...

  17. Microwave parametric amplifiers using externally pumped Josephson junctions

    DEFF Research Database (Denmark)

    Sørensen, O. H.; Mygind, Jesper; Pedersen, Niels Falsig

    1978-01-01

    Externally pumped parametric amplifiers are discussed. Theory and experiments on the singly degenerate parametric amplifier based on a Josephson junction are presented. Advantages and limitations of the singly degenerate and doubly degenerate parametric amplifiers are discussed. Some plans and pr...

  18. Low-Cost Multi-Junction Photovoltaic Cells Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed SBIR project will provide a pathway to dramatically reduce the cost of multi-junction solar cells. The project leverages a TRL6 micropackaging process...

  19. Utilizing Semantic Interpretation of Junctions for 3D-2D Pose Estimation

    DEFF Research Database (Denmark)

    Pilz, Florian; Shi, Y.; Grest, D.

    2007-01-01

    make us of this information referred as the semantic interpretation, to identify the different types of junctions (i.e. L-junctions and T-junctions). T-junctions often denote occluding contour, and thus do not designate a point in space. We show that the se- mantic interpretations is useful...

  20. Quantum statistical theory of semiconductor junctions in thermal equilibrium

    Science.gov (United States)

    Von Roos, O.

    1977-01-01

    Free carrier and electric field distributions of one-dimensional semiconductor junctions are evaluated using a quantum mechanical phase-space distribution and its corresponding Boltzmann equation. Attention is given to quantum and exchange corrections in cases of high doping concentrations when carrier densities become degenerate. Quantitative differences between degenerate and classical junction characteristics, e.g., maximum electric field and built-in voltage and carrier concentration within the transition region, are evaluated numerically.

  1. Ureteropelvic junction obstruction caused by Fibroepithelial polyps in children

    OpenAIRE

    Knoblich, Maria; Vital, Vanda; Cardoso, Dinorah; Alves, Fátima; Mota, Filipe; Casella, Paolo

    2017-01-01

    Fibroepithelial polyps are extremely rare benign tumors arising from mesodermal tissue in the ureteral wall in children, that can cause ureteropelvic junction obstruction. In this report, we present an 11‐year‐old boy complaining of left intermitent lumbar pain related with ipsilateral hydronephrosis. Surgical exploration revealed several endoluminal polyps located at the ureteropelvic junction, obstructing the lumen of the ureter. Standard treatment consists in resection of the affected uret...

  2. Formation of neuromuscular junctions in rat embryo cell cultures

    International Nuclear Information System (INIS)

    Koenig, Jeanine

    1978-01-01

    The morphological evidence of the primary nerve muscle contacts are described. They consist of areas of cholinesterase activity (detected histochemically) localized on the myotube membranes and of multiple clusters of ACh receptors whose 125 I-α-bungarotoxin binding sites are revealed by radioautography. After the stage of the primary nerve muscle contacts, some of which seem transient, characteristic neuromuscular junctions appear. These neuromuscular junctions which possess subneural infoldings are similar to the end-plates of the rat in vivo [fr

  3. Observation of nuclear gamma resonance with superconducting tunnel junction detectors

    Directory of Open Access Journals (Sweden)

    M. G. Kozin

    2016-02-01

    Full Text Available Nb-based superconducting tunnel junction detectors have been used for the registration of electrons following a nuclear gamma resonance (Mössbauer effect. Electrons were produced by a RhFe scatterer under irradiation by the 57Co(Rh Mössbauer source. This observation demonstrates the role which can be played by superconducting tunnel junction detectors in the field of conversion electron Mössbauer spectroscopy and other types of electron spectroscopy.

  4. Graphene/silicon nanowire Schottky junction for enhanced light harvesting.

    Science.gov (United States)

    Fan, Guifeng; Zhu, Hongwei; Wang, Kunlin; Wei, Jinquan; Li, Xinming; Shu, Qinke; Guo, Ning; Wu, Dehai

    2011-03-01

    Schottky junction solar cells are assembled by directly coating graphene films on n-type silicon nanowire (SiNW) arrays. The graphene/SiNW junction shows enhanced light trapping and faster carrier transport compared to the graphene/planar Si structure. With chemical doping, the SiNW-based solar cells showed energy conversion efficiencies of up to 2.86% at AM1.5 condition, opening a possibility of using graphene/semiconductor nanostructures in photovoltaic application.

  5. Using ion irradiation to make high-Tc Josephson junctions

    International Nuclear Information System (INIS)

    Bergeal, N.; Lesueur, J.; Sirena, M.; Faini, G.; Aprili, M.; Contour, J. P.; Leridon, B.

    2007-01-01

    In this article we describe the effect of ion irradiation on high-T c superconductor thin film and its interest for the fabrication of Josephson junctions. In particular, we show that these alternative techniques allow to go beyond most of the limitations encountered in standard junction fabrication methods, both in the case of fundamental and technological purposes. Two different geometries are presented: a planar one using a single high-T c film and a mesa one defined in a trilayer structure

  6. Dynamical Properties of Two-Dimensional Josephson Junction Arrays

    Science.gov (United States)

    1990-05-01

    current, i,0 , simply by Ic. = Mico , where M = 1000 is the number of junctions in parallel across the width of the array perpendicular to the current...identical junctions or some other form of disorder, the motion may be more complex , including effects such as vortex lattice shear. At higher temperatures...with the rf drive current as proposed in the vortex motion model. We have found interesting and complex dynamical behavior in the simulations that

  7. Effect of surface losses on soliton propagation in Josephson junctions

    DEFF Research Database (Denmark)

    Davidson, A.; Pedersen, Niels Falsig; Pagano, S.

    1986-01-01

    We have explored numerically the effects on soliton propagation of a third order damping term in the modified sine-Gordon equation. In Josephson tunnel junctions such a term corresponds physically to quasiparticle losses within the metal electrodes of the junction. We find that this loss term plays...... the dominant role in determining the shape and stability of the soliton at high velocity. Applied Physics Letters is copyrighted by The American Institute of Physics....

  8. Finding the optimal lengths for three branches at a junction.

    Science.gov (United States)

    Woldenberg, M J; Horsfield, K

    1983-09-21

    This paper presents an exact analytical solution to the problem of locating the junction point between three branches so that the sum of the total costs of the branches is minimized. When the cost per unit length of each branch is known the angles between each pair of branches can be deduced following reasoning first introduced to biology by Murray. Assuming the outer ends of each branch are fixed, the location of the junction and the length of each branch are then deduced using plane geometry and trigonometry. The model has applications in determining the optimal cost of a branch or branches at a junction. Comparing the optimal to the actual cost of a junction is a new way to compare cost models for goodness of fit to actual junction geometry. It is an unambiguous measure and is superior to comparing observed and optimal angles between each daughter and the parent branch. We present data for 199 junctions in the pulmonary arteries of two human lungs. For the branches at each junction we calculated the best fitting value of x from the relationship that flow alpha (radius)x. We found that the value of x determined whether a junction was best fitted by a surface, volume, drag or power minimization model. While economy of explanation casts doubt that four models operate simultaneously, we found that optimality may still operate, since the angle to the major daughter is less than the angle to the minor daughter. Perhaps optimality combined with a space filling branching pattern governs the branching geometry of the pulmonary artery.

  9. Craniovertebral junction stenosis in Lenz-Majewski syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Mizuguchi, Koichi; Ishigro, Akira [National Center for Child Health and Development, Department of General Pediatrics and Interdisciplinary Medicine, Setagaya-ku, Tokyo (Japan); Miyazaki, Osamu [National Center for Child Health and Development, Department of Radiology, Tokyo (Japan); Nishimura, Gen [Tokyo Metropolitan Children' s Medical Center, Department of Pediatric Imaging, Tokyo (Japan)

    2015-09-15

    We report a girl with Lenz-Majewski syndrome associated with craniovertebral junction stenosis that led to communicating hydrocephalus and cervical myelopathy. The life-threatening complication was related to progressive craniovertebral hyperostosis that rapidly exacerbated during early childhood. Despite initial success of surgical intervention at 2 years of age, she developed apneic spells and died suddenly at age 5 years. Close monitoring for craniovertebral junction stenosis is essential to reduce morbidity and mortality in children with Lenz-Majewski syndrome. (orig.)

  10. The string-junction picture of multiquark states: an update

    Science.gov (United States)

    Rossi, G. C.; Veneziano, G.

    2016-06-01

    We recall and update, both theoretically and phenomenologically, our (nearly) forty-years-old proposal of a string-junction as a necessary complement to the conventional classification of hadrons based just on their quark-antiquark constituents. In that proposal single (though in general metastable) hadronic states are associated with "irreducible" gauge-invariant operators consisting of Wilson lines (visualized as strings of color flux tubes) that may either end on a quark or an antiquark, or annihilate in triplets at a junction J or an anti-junction overline{J} . For the junction-free sector (ordinary qoverline{q} mesons and glueballs) the picture is supported by large- N (number of colors) considerations as well as by a lattice strong-coupling expansion. Both imply the famous OZI rule suppressing quark-antiquark annihilation diagrams. For hadrons with J and/or overline{J} constituents the same expansions support our proposal, including its generalization of the OZI rule to the suppression of J-overline{J} annihilation diagrams. Such a rule implies that hadrons with junctions are "mesophobic" and thus unusually narrow if they are below threshold for decaying into as many baryons as their total number of junctions (two for a tetraquark, three for a pentaquark). Experimental support for our claim, based on the observation that narrow multiquark states typically lie below (well above) the relevant baryonic (mesonic) thresholds, will be presented.

  11. Predicting helical topologies in RNA junctions as tree graphs.

    Directory of Open Access Journals (Sweden)

    Christian Laing

    Full Text Available RNA molecules are important cellular components involved in many fundamental biological processes. Understanding the mechanisms behind their functions requires knowledge of their tertiary structures. Though computational RNA folding approaches exist, they often require manual manipulation and expert intuition; predicting global long-range tertiary contacts remains challenging. Here we develop a computational approach and associated program module (RNAJAG to predict helical arrangements/topologies in RNA junctions. Our method has two components: junction topology prediction and graph modeling. First, junction topologies are determined by a data mining approach from a given secondary structure of the target RNAs; second, the predicted topology is used to construct a tree graph consistent with geometric preferences analyzed from solved RNAs. The predicted graphs, which model the helical arrangements of RNA junctions for a large set of 200 junctions using a cross validation procedure, yield fairly good representations compared to the helical configurations in native RNAs, and can be further used to develop all-atom models as we show for two examples. Because junctions are among the most complex structural elements in RNA, this work advances folding structure prediction methods of large RNAs. The RNAJAG module is available to academic users upon request.

  12. Predicting helical topologies in RNA junctions as tree graphs.

    Science.gov (United States)

    Laing, Christian; Jung, Segun; Kim, Namhee; Elmetwaly, Shereef; Zahran, Mai; Schlick, Tamar

    2013-01-01

    RNA molecules are important cellular components involved in many fundamental biological processes. Understanding the mechanisms behind their functions requires knowledge of their tertiary structures. Though computational RNA folding approaches exist, they often require manual manipulation and expert intuition; predicting global long-range tertiary contacts remains challenging. Here we develop a computational approach and associated program module (RNAJAG) to predict helical arrangements/topologies in RNA junctions. Our method has two components: junction topology prediction and graph modeling. First, junction topologies are determined by a data mining approach from a given secondary structure of the target RNAs; second, the predicted topology is used to construct a tree graph consistent with geometric preferences analyzed from solved RNAs. The predicted graphs, which model the helical arrangements of RNA junctions for a large set of 200 junctions using a cross validation procedure, yield fairly good representations compared to the helical configurations in native RNAs, and can be further used to develop all-atom models as we show for two examples. Because junctions are among the most complex structural elements in RNA, this work advances folding structure prediction methods of large RNAs. The RNAJAG module is available to academic users upon request.

  13. Dynamics of fractional vortices in long Josephson junctions

    International Nuclear Information System (INIS)

    Gaber, Tobias

    2007-01-01

    In this thesis static and dynamic properties of fractional vortices in long Josephson junctions are investigated. Fractional vortices are circulating supercurrents similar to the well-known Josephson fluxons. Yet, they show the distinguishing property of carrying only a fraction of the magnetic flux quantum. Fractional vortices are interesting non-linear objects. They spontaneously appear and are pinned at the phase discontinuity points of so called 0-κ junctions but can be bend or flipped by external forces like bias currents or magnetic fields. 0-κ junctions and fractional vortices are generalizations of the well-known 0-π junctions and semifluxons, where not only phase jumps of pi but arbitrary values denoted by kappa are considered. By using so-called artificial 0-κ junctions that are based on standard Nb-AlO x -Nb technology the classical dynamics of fractional vortices has been investigated experimentally for the very first time. Here, half-integer zero field steps could be observed. These voltage steps on the junction's current-voltage characteristics correspond to the periodic flipping/hopping of fractional vortices. In addition, the oscillatory eigenmodes of fractional vortices were investigated. In contrast to fluxons fractional vortices have an oscillatory eigenmode with a frequency within the plasma gap. Using resonance spectroscopy the dependence of the eigenmode frequency on the flux carried by the vortex and an applied bias current was determined. (orig.)

  14. Affordance-based individuation of junctions in Open Street Map

    Directory of Open Access Journals (Sweden)

    Simon Scheider

    2012-06-01

    Full Text Available We propose an algorithm that can be used to identify automatically the subset of street segments of a road network map that corresponds to a junction. The main idea is to use turn-compliant locomotion affordances, i.e., restricted patterns of supported movement, in order to specify junctions independently of their data representation, and in order to motivate tractable individuation and classification strategies. We argue that common approaches based solely on geometry or topology of the street segment graph are useful but insufficient proxies. They miss certain turn restrictions essential to junctions. From a computational viewpoint, the main challenge of affordance-based individuation of junctions lies in its complex recursive definition. In this paper, we show how Open Street Map data can be interpreted into locomotion affordances, and how the recursive junction definition can be translated into a deterministic algorithm. We evaluate this algorithm by applying it to small map excerpts in order to delineate the contained junctions.

  15. The string-junction picture of multiquark states: an update

    Energy Technology Data Exchange (ETDEWEB)

    Rossi, G.C. [Dipartimento di Fisica, Università di Roma Tor Vergata, INFN, Sezione di Roma 2, Via della Ricerca Scientifica, 00133 Roma (Italy); Centro Fermi, Museo Storico della Fisica,Piazza del Viminale 1, 00184 Roma (Italy); Veneziano, G. [Collège de France,11 place M. Berthelot, 75005 Paris (France); Theory Division, CERN,CH-1211 Geneva 23 (Switzerland); Dipartimento di Fisica, Università di Roma La Sapienza,Piazzale A. Moro 5, 00185 Roma (Italy)

    2016-06-07

    We recall and update, both theoretically and phenomenologically, our (nearly) forty-years-old proposal of a string-junction as a necessary complement to the conventional classification of hadrons based just on their quark-antiquark constituents. In that proposal single (though in general metastable) hadronic states are associated with “irreducible' gauge-invariant operators consisting of Wilson lines (visualized as strings of color flux tubes) that may either end on a quark or an antiquark, or annihilate in triplets at a junction J or an anti-junction J̄. For the junction-free sector (ordinary q q̄ mesons and glueballs) the picture is supported by large-N (number of colors) considerations as well as by a lattice strong-coupling expansion. Both imply the famous OZI rule suppressing quark-antiquark annihilation diagrams. For hadrons with J and/or J̄ constituents the same expansions support our proposal, including its generalization of the OZI rule to the suppression of J−J̄ annihilation diagrams. Such a rule implies that hadrons with junctions are “mesophobic' and thus unusually narrow if they are below threshold for decaying into as many baryons as their total number of junctions (two for a tetraquark, three for a pentaquark). Experimental support for our claim, based on the observation that narrow multiquark states typically lie below (well above) the relevant baryonic (mesonic) thresholds, will be presented.

  16. Renal trauma in occult ureteropelvic junction obstruction: CT findings

    Energy Technology Data Exchange (ETDEWEB)

    Sebastia, M.C.; Rodriguez-Dobao, M.; Quiroga, S.; Pallisa, E.; Martinez-Rodriguez, M.; Alvarez-Castells, A. [Dept. of Radiology, Hospital General Universitari Vall d`Hebron, Barcelona (Spain)

    1999-05-01

    The aim of this study was to present CT findings of occult ureteropelvic junction obstruction in patients with renal trauma and to describe the clinical signs and singular CT features that are characteristically observed with trauma and are relevant to management of these patients. We retrospectively reviewed 82 helical CT studies in patients with renal trauma referred to our institution. We found 13 cases of occult preexisting renal pathology, six of which were occult ureteropelvic junction obstructions. The clinical presentation, radiologic findings of trauma according to the Federle classification, and CT findings of obstructed ureteropelvic junction are presented. We found three category-I lesions (one in a horseshoe kidney), two of them treated with nephrostomy because of increased ureteropelvic junction obstruction due to pelvic clots; two category-II lesions (parenchymal and renal pelvis lacerations) that had presented only with microhematuria; and one category-IV lesion (pelvic laceration alone). Pelvic extension was demonstrated in all the cases with perirenal collections. The CT studies in all the cases with suspected ureteropelvic junction obstruction showed decreased parenchymal thickness and enhancement, and dilatation of the renal pelvis and calyx, with a normal ureter. Computed tomography can provide information to confidently diagnose underlying ureteropelvic junction obstruction in renal trauma, categorize the traumatic injury (at times clinically silent) and facilitate proper management according to the singularities observed, such us rupture of the renal pelvis alone (Federle category IV) and increasing ureteropelvic obstruction due to clots which can be decompressed by nephrostomy. (orig.) With 6 figs., 3 tabs., 13 refs.

  17. Anchored PKA as a gatekeeper for gap junctions.

    Science.gov (United States)

    Pidoux, Guillaume; Taskén, Kjetil

    2015-01-01

    Anchored protein kinase A (PKA) bound to A Kinase Anchoring Protein (AKAP) mediates effects of localized increases in cAMP in defined subcellular microdomains and retains the specificity in cAMP-PKA signaling to distinct extracellular stimuli. Gap junctions are pores between adjacent cells constituted by connexin proteins that provide means of communication and transfer of small molecules. While the PKA signaling is known to promote human trophoblast cell fusion, the gap junction communication through connexin 43 (Cx43) is a prerequisite for this process. We recently demonstrated that trophoblast fusion is regulated by ezrin, a known AKAP, which binds to Cx43 and delivers PKA in the vicinity gap junctions. We found that disruption of the ezrin-Cx43 interaction abolished PKA-dependent phosphorylation of Cx43 as well as gap junction communication and subsequently cell fusion. We propose that the PKA-ezrin-Cx43 macromolecular complex regulating gap junction communication constitutes a general mechanism to control opening of Cx43 gap junctions by phosphorylation in response to cAMP signaling in various cell types.

  18. Entropy Flow Through Near-Critical Quantum Junctions

    Science.gov (United States)

    Friedan, Daniel

    2017-05-01

    This is the continuation of Friedan (J Stat Phys, 2017. doi: 10.1007/s10955-017-1752-8). Elementary formulas are derived for the flow of entropy through a circuit junction in a near-critical quantum circuit close to equilibrium, based on the structure of the energy-momentum tensor at the junction. The entropic admittance of a near-critical junction in a bulk-critical circuit is expressed in terms of commutators of the chiral entropy currents. The entropic admittance at low frequency, divided by the frequency, gives the change of the junction entropy with temperature—the entropic "capacitance". As an example, and as a check on the formalism, the entropic admittance is calculated explicitly for junctions in bulk-critical quantum Ising circuits (free fermions, massless in the bulk), in terms of the reflection matrix of the junction. The half-bit of information capacity per end of critical Ising wire is re-derived by integrating the entropic "capacitance" with respect to temperature, from T=0 to T=∞.

  19. Predicting Helical Topologies in RNA Junctions as Tree Graphs

    Science.gov (United States)

    Kim, Namhee; Elmetwaly, Shereef; Zahran, Mai; Schlick, Tamar

    2013-01-01

    RNA molecules are important cellular components involved in many fundamental biological processes. Understanding the mechanisms behind their functions requires knowledge of their tertiary structures. Though computational RNA folding approaches exist, they often require manual manipulation and expert intuition; predicting global long-range tertiary contacts remains challenging. Here we develop a computational approach and associated program module (RNAJAG) to predict helical arrangements/topologies in RNA junctions. Our method has two components: junction topology prediction and graph modeling. First, junction topologies are determined by a data mining approach from a given secondary structure of the target RNAs; second, the predicted topology is used to construct a tree graph consistent with geometric preferences analyzed from solved RNAs. The predicted graphs, which model the helical arrangements of RNA junctions for a large set of 200 junctions using a cross validation procedure, yield fairly good representations compared to the helical configurations in native RNAs, and can be further used to develop all-atom models as we show for two examples. Because junctions are among the most complex structural elements in RNA, this work advances folding structure prediction methods of large RNAs. The RNAJAG module is available to academic users upon request. PMID:23991010

  20. Negative differential resistance in Josephson junctions coupled to a cavity

    Energy Technology Data Exchange (ETDEWEB)

    Pedersen, N.F. [Department of Applied Mathematics and Computer Science, Technical University of Denmark, 2800 Kgs. Lyngby (Denmark); Filatrella, G., E-mail: filatrella@unisannio.it [Department of Science and Technology, University of Sannio (Italy); Pierro, V. [Department of Engineering, University of Sannio (Italy); Sørensen, M.P. [Department of Applied Mathematics and Computer Science, Technical University of Denmark, 2800 Kgs. Lyngby (Denmark)

    2014-08-15

    Highlights: • A simple model for the negative differential resistance observed in JJ arrays. • The N- and S-shape differential resistances are included in JJ models. • A single junction model mimics the behavior of stacks of Josephson junctions. • A peak in the power is linked to the negative differential resistance. • Relevant to model emission in millimeter wave device, e.g. circuits and antennas. - Abstract: Regions with negative differential resistance can arise in the IV curve of Josephson junctions and this phenomenon plays an essential role for applications, in particular for THz radiation emission. For the measurement of high frequency radiation from Josephson junctions, a cavity – either internal or external – is often used. A cavity may also induce a negative differential resistance region at the lower side of the resonance frequency. We investigate the dynamics of Josephson junctions with a negative differential resistance in the quasi particle tunnel current, i.e. in the McCumber curve. We find that very complicated and unexpected interactions take place. This may be useful for the interpretation of experimental measurements of THz radiation from intrinsic Josephson junctions.

  1. Electric-field-induced magnetization switching in CoFeB/MgO magnetic tunnel junctions with high junction resistance

    Science.gov (United States)

    Kanai, S.; Matsukura, F.; Ohno, H.

    2016-05-01

    We show the electric-field induced magnetization switching for CoFeB/MgO magnetic tunnel junctions with thick MgO barrier layer of 2.8 nm, whose resistance-area product is 176 kΩ μm2, and achieve the small switching energy of 6.3 fJ/bit. The increase of the junction resistance is expected to suppress the energy consumption due to the Joule heating during the switching; however, the energy is still dominated by the Joule energy rather than the charging energy. This is because the junction resistance decreases more rapidly for junctions with thicker MgO as bias voltage increases.

  2. Hydrologically Connected Road Segments

    Data.gov (United States)

    Vermont Center for Geographic Information — Link it ArcGIS Item is HERE.The connectivity layer was created to assist municipalities in preparing for the forthcoming DEC Municipal Roads General Permit in 2018....

  3. How connected vehicles work.

    Science.gov (United States)

    2011-01-01

    Connected vehicles have the potential to transform the way Americans travel through the creation : of a safe, interoperable wireless communications networka system that includes cars, buses, : trucks, trains, traffic signals, cell phones, and othe...

  4. Connected motorcycle system performance.

    Science.gov (United States)

    2016-01-15

    This project characterized the performance of Connected Vehicle Systems (CVS) on motorcycles based on two key components: global positioning and wireless communication systems. Considering that Global Positioning System (GPS) and 5.9 GHz Dedicated Sh...

  5. Connected vehicle applications : environment.

    Science.gov (United States)

    2016-01-01

    The U.S. Department of Transportation has developed a number of connected vehicle environmental : applications, including the Applications for the Environment Real-Time Information Synthesis (AERIS) : research program applications and road weather ap...

  6. Connected vehicle applications : safety.

    Science.gov (United States)

    2016-01-01

    Connected vehicle safety applications are designed to increase situational awareness : and reduce or eliminate crashes through vehicle-to-infrastructure, vehicle-to-vehicle, : and vehicle-to-pedestrian data transmissions. Applications support advisor...

  7. Connected vehicles and cybersecurity.

    Science.gov (United States)

    2016-01-01

    Connected vehicles are a next-generation technology in vehicles and in infrastructure : that will make travel safer, cleaner, and more efficient. The advanced wireless : technology enables vehicles to share and communicate information with each other...

  8. Junction-to-Case Thermal Resistance of a Silicon Carbide Bipolar Junction Transistor Measured

    Science.gov (United States)

    Niedra, Janis M.

    2006-01-01

    Junction temperature of a prototype SiC-based bipolar junction transistor (BJT) was estimated by using the base-emitter voltage (V(sub BE)) characteristic for thermometry. The V(sub BE) was measured as a function of the base current (I(sub B)) at selected temperatures (T), all at a fixed collector current (I(sub C)) and under very low duty cycle pulse conditions. Under such conditions, the average temperature of the chip was taken to be the same as that of the temperature-controlled case. At increased duty cycle such as to substantially heat the chip, but same I(sub C) pulse height, the chip temperature was identified by matching the V(sub BE) to the thermometry curves. From the measured average power, the chip-to-case thermal resistance could be estimated, giving a reasonable value. A tentative explanation for an observed bunching with increasing temperature of the calibration curves may relate to an increasing dopant atom ionization. A first-cut analysis, however, does not support this.

  9. A Three-Isocenter Jagged-Junction IMRT Approach for Craniospinal Irradiation Without Beam Edge Matching for Field Junctions

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Fred, E-mail: fcao@bccancer.bc.ca [Department of Medical Physics, Fraser Valley Centre, BC Cancer Agency, Surrey, British Columbia (Canada); Ramaseshan, Ramani; Corns, Robert; Harrop, Sheryl [Department of Medical Physics, Fraser Valley Centre, BC Cancer Agency, Surrey, British Columbia (Canada); Nuraney, Nimet; Steiner, Peter; Aldridge, Stephanie [Department of Radiation Oncology, Fraser Valley Centre, BC Cancer Agency, Surrey, British Columbia (Canada); Liu, Mitchell; Carolan, Hannah [Department of Radiation Oncology, Vancouver Centre, BC Cancer Agency, Vancouver, British Columbia (Canada); Agranovich, Alex; Karvat, Anand [Department of Radiation Oncology, Fraser Valley Centre, BC Cancer Agency, Surrey, British Columbia (Canada)

    2012-11-01

    Purpose: Traditionally craniospinal irradiation treats the central nervous system using two or three adjacent field sets. We propose a technique using a three-isocenter intensity-modulated radiotherapy (IMRT) plan (jagged-junction IMRT) which overcomes problems associated with field junctions and beam edge matching and improves planning and treatment setup efficiencies with homogenous target dose distribution. Methods and Materials: Treatments for 3 patients with a prescription of 36 Gy in 20 fractions were retrospectively planned with jagged-junction IMRT and compared to conventional treatment plans. Planning target volume (PTV) included the whole brain and spinal canal to the S3 vertebral level. The plan used three field sets, each with a unique isocenter. One field set with seven fields treated the cranium. Two field sets treated the spine, each set using three fields. Fields from adjacent sets were overlapped, and the optimization process smoothly integrated the dose inside the overlapped junction. Results: For jagged-junction IMRT plans vs. conventional technique, the average homogeneity index equaled 0.08 {+-} 0.01 vs. 0.12 {+-} 0.02, respectively, and conformity number equaled 0.79 {+-} 0.01 vs. 0.47 {+-} 0.12, respectively. The 95% isodose surface covered (99.5 {+-} 0.3)% of the PTV vs. (98.1 {+-} 2.0)%, respectively. Both jagged-junction IMRT plans and the conventional plans had good sparing of organs at risk. Conclusions: Jagged-junction IMRT planning provided good dose homogeneity and conformity to the target while maintaining a low dose to organs at risk. Results from jagged-junction IMRT plans were better than or equivalent to those from the conventional technique. Jagged-junction IMRT optimization smoothly distributed dose in the junction between field sets. Because there was no beam matching, this treatment technique is less likely to produce hot or cold spots at the junction, in contrast to conventional techniques. The planning process is also

  10. A Three-Isocenter Jagged-Junction IMRT Approach for Craniospinal Irradiation Without Beam Edge Matching for Field Junctions

    International Nuclear Information System (INIS)

    Cao, Fred; Ramaseshan, Ramani; Corns, Robert; Harrop, Sheryl; Nuraney, Nimet; Steiner, Peter; Aldridge, Stephanie; Liu, Mitchell; Carolan, Hannah; Agranovich, Alex; Karvat, Anand

    2012-01-01

    Purpose: Traditionally craniospinal irradiation treats the central nervous system using two or three adjacent field sets. We propose a technique using a three-isocenter intensity-modulated radiotherapy (IMRT) plan (jagged-junction IMRT) which overcomes problems associated with field junctions and beam edge matching and improves planning and treatment setup efficiencies with homogenous target dose distribution. Methods and Materials: Treatments for 3 patients with a prescription of 36 Gy in 20 fractions were retrospectively planned with jagged-junction IMRT and compared to conventional treatment plans. Planning target volume (PTV) included the whole brain and spinal canal to the S3 vertebral level. The plan used three field sets, each with a unique isocenter. One field set with seven fields treated the cranium. Two field sets treated the spine, each set using three fields. Fields from adjacent sets were overlapped, and the optimization process smoothly integrated the dose inside the overlapped junction. Results: For jagged-junction IMRT plans vs. conventional technique, the average homogeneity index equaled 0.08 ± 0.01 vs. 0.12 ± 0.02, respectively, and conformity number equaled 0.79 ± 0.01 vs. 0.47 ± 0.12, respectively. The 95% isodose surface covered (99.5 ± 0.3)% of the PTV vs. (98.1 ± 2.0)%, respectively. Both jagged-junction IMRT plans and the conventional plans had good sparing of organs at risk. Conclusions: Jagged-junction IMRT planning provided good dose homogeneity and conformity to the target while maintaining a low dose to organs at risk. Results from jagged-junction IMRT plans were better than or equivalent to those from the conventional technique. Jagged-junction IMRT optimization smoothly distributed dose in the junction between field sets. Because there was no beam matching, this treatment technique is less likely to produce hot or cold spots at the junction, in contrast to conventional techniques. The planning process is also simplified as

  11. Vortex dynamics in Josephson junctions arrays

    International Nuclear Information System (INIS)

    Shalom, Diego Edgar

    2005-01-01

    In this work we study the dynamics of vortices in two-dimensional overdamped Josephson Junctions Arrays (JJA) driven by dc current in a wide range of conditions varying magnetic field and temperature using experiments, numerical simulations and analytic studies.We develop the Fixed Phase method, a variation of numeric relaxation techniques in which we fix and control the phase of some islands, adjacent to the vortex center, while allowing all other phases in the system to relax.In this way we are able to pull and push the vortex uphill, as we are forcing the center of rotation of the vortex currents to be in a defined location, allowing us to calculate the potential energy of a vortex located in any arbitrary position.We use this method to study the potential energy of a vortex in a variety of situations in homogeneous and non-homogeneous JJA, such as arrays with defects, channel arrays and ratchets.We study the finite size effects in JJA by means of analytic and numerical tools.We implement the rings model, in which we replace the two-dimensional square array by a series of square, concentric, uncoupled rings. This is equivalent to disregarding the radial junctions that couple consecutive rings.In spite of its extreme simplicity, this model holds the main ingredients of the magnetic dependence of the energy.We combine this model with other terms that take into account the dependence in the position of the vortex to obtain a general expression for the potential energy of a vortex in a finite JJA with applied magnetic field.We also present an expression for the first critical field, corresponding to the value of the magnetic field in which the entrance of the first vortex becomes energetically favorable.We build and study JJA modulated to form periodic and asymmetrical potentials for the vortices, named ratchet potentials.The experimental results clearly show the existence of a rectification in the motion of vortices in these potentials.Under certain conditions we

  12. Quaternary Evolution of Karliova Triple Junction

    Science.gov (United States)

    Sançar, Taylan; Zabcı, Cengiz; Akyüz, H. Serdar

    2013-04-01

    The arguments to explain Quaternary evolution of Karlıova Triple Junction (KTJ) depends upon two different analogue models. The compressional type of Prandtl Cell Model (PCM) and 60 km wide shear zone with concomitant counter clockwise block rotation used to modelled for west and east of the KTJ respectively. The data for the model of west of the KTJ acquired by extensive field studies, and quantified geomorphic features. Compressional PCM put forward that behavior of slip lines controlled by boundary faults. But the model is not enough to explain slip distribution, age relation of them. At west of the KTJ boundary faults presented by eastern most segments of the North Anatolian Fault Zone (NAFZ) and the East Anatolian Fault Zone (EAFZ). Slip lines, however, presented by Bahçeli and Toklular faults. Both field studies and morphometric analyses undisputedly set forth that there are two different fault types between the NAFZ and EAFZ. The most strain loaded fault type, which are positioned near the NAFZ, start as a strike-slip fault and when it turn to SE its sense of motion change to oblique normal due to changing orientation of principal stress axes. The new orientation of stress axes exposed in the field as a special kind of caprock -cuesta-. The younger slip lines formed very close to junction point and accommodate less slip. Even though slip trajectories started from the boundary faults in compressional PCM, at the west of KTJ, right lateral trajectories more clearly formed close the NAFZ and left lateral trajectories, relatively less strain loaded fault type, are poorly formed close the EAFZ . We think that, this differences between KTJ and compressional PCM result from the distinction of velocity of boundary faults. East of the KTJ governed by completely different mechanism. The region controlled two main fault systems. The Varto Fault Zone (VFZ), the eastern branch of the KTJ, and Murat Fault (MF) delimited the region from north and south respectively. The

  13. Elongated nanostructures for radial junction solar cells.

    Science.gov (United States)

    Kuang, Yinghuan; Vece, Marcel Di; Rath, Jatindra K; Dijk, Lourens van; Schropp, Ruud E I

    2013-10-01

    In solar cell technology, the current trend is to thin down the active absorber layer. The main advantage of a thinner absorber is primarily the reduced consumption of material and energy during production. For thin film silicon (Si) technology, thinning down the absorber layer is of particular interest since both the device throughput of vacuum deposition systems and the stability of the devices are significantly enhanced. These features lead to lower cost per installed watt peak for solar cells, provided that the (stabilized) efficiency is the same as for thicker devices. However, merely thinning down inevitably leads to a reduced light absorption. Therefore, advanced light trapping schemes are crucial to increase the light path length. The use of elongated nanostructures is a promising method for advanced light trapping. The enhanced optical performance originates from orthogonalization of the light's travel path with respect to the direction of carrier collection due to the radial junction, an improved anti-reflection effect thanks to the three-dimensional geometric configuration and the multiple scattering between individual nanostructures. These advantages potentially allow for high efficiency at a significantly reduced quantity and even at a reduced material quality, of the semiconductor material. In this article, several types of elongated nanostructures with the high potential to improve the device performance are reviewed. First, we briefly introduce the conventional solar cells with emphasis on thin film technology, following the most commonly used fabrication techniques for creating nanostructures with a high aspect ratio. Subsequently, several representative applications of elongated nanostructures, such as Si nanowires in realistic photovoltaic (PV) devices, are reviewed. Finally, the scientific challenges and an outlook for nanostructured PV devices are presented.

  14. Free vibration analysis of dissimilar connected CNTs with atomic imperfections and different locations of connecting region

    Science.gov (United States)

    Mohammadian, Mostafa; Hosseini, Seyed Mahmoud; Abolbashari, Mohammad Hossein

    2017-11-01

    In this paper, the vibrational characteristics of hetero-junction carbon nanotubes (HJCNTs) are investigated using the well-known molecular mechanics approach. The paper contains two main novel parts. In the first part, the influence of connecting region location on the first five natural frequencies of perfect HJCNTs is investigated. In the second part, the effects of some common defects on fundamental frequencies are studied. The study is performed for different boundary conditions and different structures of HJCNTs. The results show that the frequencies and mode shapes are effectively influenced by changing the location of connecting region. Interestingly, it is found that the frequencies of HJCNTs can be even higher than those of their constituent CNTs for a specific location of connecting region. In the second part, it is shown that the fundamental frequency of HJCNTs decreases with introducing the defects. Furthermore, the frequency shift of defective structures with lower aspect ratios is more affected by the level of imperfections. Finally, the obtained numerical results are adopted to develop a predictive equation for calculating the fundamental frequency shift of defective straight HJCNTs based on the kind and level of defect, aspect ratio as well as the type of boundary conditions.

  15. The influence of junction conformation on RNA cleavage by the hairpin ribozyme in its natural junction form.

    Science.gov (United States)

    Thomson, J B; Lilley, D M

    1999-01-01

    In the natural form of the hairpin ribozyme the two loop-carrying duplexes that comprise the majority of essential bases for activity form two adjacent helical arms of a four-way RNA junction. In the present work we have manipulated the sequence around the junction in a way known to perturb the global folding properties. We find that replacement of the junction by a different sequence that has the same conformational properties as the natural sequence gives closely similar reaction rate and Arrhenius activation energy for the substrate cleavage reaction. By comparison, rotation of the natural sequence in order to alter the three-dimensional folding of the ribozyme leads to a tenfold reduction in the kinetics of cleavage. Replacement with the U1 four-way junction that is resistant to rotation into the antiparallel structure required to allow interaction between the loops also gives a tenfold reduction in cleavage rate. The results indicate that the conformation of the junction has a major influence on the catalytic activity of the ribozyme. The results are all consistent with a role for the junction in the provision of a framework by which the loops are presented for interaction in order to create the active form of the ribozyme. PMID:10024170

  16. [Experimental work: reconstruction of the pelvi-ureteric junction and ureter using testicular tunica vaginalis autograft].

    Science.gov (United States)

    Usupbaev, A Ch; Kurbanaliev, R M; Chernetsova, G S; Kolesnichenko, I V; Sultanov, B M; Myrzakanov, N M; Zolotukhin, A O; Vagner, N A

    2017-12-01

    To evaluate the results of surgical reconstruction of the upper urinary tract using an autograft of testicular tunica vaginalis in experimental animals. The article presents the results of partial replacement of the renal pelvis and ureter with an autograft in 25 male dogs. The grafts were harvested by resection of the parietal layer of the testicular tunica vaginalis, which was transplanted into the region of the pelvi-ureteric junction and the proximal ureter. The upper urinary tract was drained using a ureteral stent catheter. The results were evaluated at week 1 and months 1, 3 and six after the operation. The functional state of the kidneys and ureters was analyzed using excretory urography and ultrasound; the autograft biopsy specimens were examined histologically. In all cases, the viability of the autograft was completely preserved, there were no signs of secondary infection, necrosis and impaired patency in the anastomosis zone. Histological examination revealed signs of epithelialization, connective tissue substitution and neovasculogenesis in the implantation zone. The proposed surgical modality is an alternative method to restore normal urine flow in the upper urinary tract in obstructive urological diseases. The group of obstructive urological diseases was studied using the model of the strictures of the pelvi-ureteric junction in the intrarenal pelvis and ureteral strictures measuring up to 3-4 cm in length.

  17. Self-limited plasmonic welding of silver nanowire junctions

    KAUST Repository

    Garnett, Erik C.

    2012-02-05

    Nanoscience provides many strategies to construct high-performance materials and devices, including solar cells, thermoelectrics, sensors, transistors, and transparent electrodes. Bottom-up fabrication facilitates large-scale chemical synthesis without the need for patterning and etching processes that waste material and create surface defects. However, assembly and contacting procedures still require further development. Here, we demonstrate a light-induced plasmonic nanowelding technique to assemble metallic nanowires into large interconnected networks. The small gaps that form naturally at nanowire junctions enable effective light concentration and heating at the point where the wires need to be joined together. The extreme sensitivity of the heating efficiency on the junction geometry causes the welding process to self-limit when a physical connection between the wires is made. The localized nature of the heating prevents damage to low-thermal-budget substrates such as plastics and polymer solar cells. This work opens new avenues to control light, heat and mass transport at the nanoscale. © 2012 Macmillan Publishers Limited. All rights reserved.

  18. Discreteness-induced resonances and ac voltage amplitudes in long one-dimensional Josephson junction arrays

    International Nuclear Information System (INIS)

    Duwel, A.E.; Watanabe, S.; Trias, E.; Orlando, T.P.; van der Zant, H.S.; Strogatz, S.H.

    1997-01-01

    New resonance steps are found in the experimental current-voltage characteristics of long, discrete, one-dimensional Josephson junction arrays with open boundaries and in an external magnetic field. The junctions are underdamped, connected in parallel, and dc biased. Numerical simulations based on the discrete sine-Gordon model are carried out, and show that the solutions on the steps are periodic trains of fluxons, phase locked by a finite amplitude radiation. Power spectra of the voltages consist of a small number of harmonic peaks, which may be exploited for possible oscillator applications. The steps form a family that can be numbered by the harmonic content of the radiation, the first member corresponding to the Eck step. Discreteness of the arrays is shown to be essential for appearance of the higher order steps. We use a multimode extension of the harmonic balance analysis, and estimate the resonance frequencies, the ac voltage amplitudes, and the theoretical limit on the output power on the first two steps. copyright 1997 American Institute of Physics

  19. Urea biosensor based on an extended-base bipolar junction transistor.

    Science.gov (United States)

    Sun, Tai-Ping; Shieh, Hsiu-Li; Liu, Chun-Lin; Chen, Chung-Yuan

    2014-01-01

    In this study, a urea biosensor was prepared by the immobilization of urease onto the sensitive membrane of an extended-base bipolar junction transistor. The pH variation was used to detect the concentration of urea. The SnO2/ITO glass, fabricated by sputtering SnO2 on the conductive ITO glass, was used as a pH-sensitive membrane, which was connected with a commercial bipolar junction transistor device. The gels, fabricated by the poly vinyl alcohol with pendent styrylpyridinium groups, were used to immobilize the urease. This readout circuit, fabricated in a 0.35-um CMOS 2P4M process, operated at 3.3V supply voltage. This circuit occupied an area of 1.0 mm × 0.9 mm. The dynamic range of the urea biosensor was from 1.4 to 64 mg/dl at the 10 mM phosphate buffer solution and the sensitivity of this range was about 65.8 mV/pUrea. The effect of urea biosensors with different pH values was considered, and the characteristics of urea biosensors based on EBBJT were described.

  20. Effect of parallel transport currents on the d-wave Josephson junction

    International Nuclear Information System (INIS)

    Rashedi, Gholamreza

    2009-01-01

    In this paper, the non-local mixing of coherent current states in d-wave superconducting banks is investigated. The superconducting banks are connected via a ballistic point contact. The banks have mis-orientation and phase difference. Furthermore, they are subjected to a tangential transport current along the ab plane of d-wave crystals and parallel to the interface between the superconductors. The effects of mis-orientation and external transport current on the current-phase relations and current distributions are the subjects of this paper. It is observed that, at values of phase difference close to 0, π and 2π, the current distribution may have a vortex-like form in the vicinity of the point contact. The current distribution of the above-mentioned junction between d-wave superconductors is totally different from the junction between s-wave superconductors. The interesting result which this study shows is that spontaneous and Josephson currents are observed for the case of φ = 0.

  1. Anomalous Tunnel Magnetoresistance and Spin Transfer Torque in Magnetic Tunnel Junctions with Embedded Nanoparticles

    Science.gov (United States)

    Useinov, Arthur; Ye, Lin-Xiu; Useinov, Niazbeck; Wu, Te-Ho; Lai, Chih-Huang

    2015-01-01

    The tunnel magnetoresistance (TMR) in the magnetic tunnel junction (MTJ) with embedded nanoparticles (NPs) was calculated in range of the quantum-ballistic model. The simulation was performed for electron tunneling through the insulating layer with embedded magnetic and non-magnetic NPs within the approach of the double barrier subsystem connected in parallel to the single barrier one. This model can be applied for both MTJs with in-plane magnetization and perpendicular one. We also calculated the in-plane component of the spin transfer torque (STT) versus the applied voltage in MTJs with magnetic NPs and determined that its value can be much larger than in single barrier system (SBS) for the same tunneling thickness. The reported simulation reproduces experimental data of the TMR suppression and peak-like TMR anomalies at low voltages available in leterature. PMID:26681336

  2. Origin of the smaller conductances of Rh, Pb, and Co atomic junctions in hydrogen environment

    Science.gov (United States)

    Li, Xue; Chen, Mingyan; Ye, Xiang; Xie, Yi-qun; Ke, San-huang

    2015-02-01

    We study theoretically the structural and electronic origins of the smaller conductances (one conductance quantum, G0, and smaller) of Rh, Pb, and Co metal atomic junctions (MAJs) in a hydrogen environment, as were measured in recent experiments. For the Rh MAJs, the 1G0 conductance is attributed to a stable contact bridged by a single hydrogen molecule whose antibonding state provides a single transport channel. For the Pb and Co MAJs the 1G0 conductance is, however, ascribed to a linear atomic chain adsorbing two dissociated H atoms, which largely reduces the density of states at the Fermi energy with respect to the pure ones. On the other hand, the small conductances of 0.3G0 (Rh) and 0.2G0 (Co) are due to H-decorated atomic chains connected to electrodes by a H atom.

  3. Origin of the smaller conductances of Rh, Pb, and Co atomic junctions in hydrogen environment

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xue; Chen, Mingyan; Ye, Xiang; Xie, Yi-qun, E-mail: yqxie@shnu.edu.cn [Department of Physics, Shanghai Normal University, 100 Guilin Road, Shanghai 200232 (China); Ke, San-huang, E-mail: shke@tongji.edu.cn [MOE Key Laboratory of Advanced Microstructured Materials, School of Physics Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092 (China)

    2015-02-14

    We study theoretically the structural and electronic origins of the smaller conductances (one conductance quantum, G{sub 0}, and smaller) of Rh, Pb, and Co metal atomic junctions (MAJs) in a hydrogen environment, as were measured in recent experiments. For the Rh MAJs, the 1G{sub 0} conductance is attributed to a stable contact bridged by a single hydrogen molecule whose antibonding state provides a single transport channel. For the Pb and Co MAJs the 1G{sub 0} conductance is, however, ascribed to a linear atomic chain adsorbing two dissociated H atoms, which largely reduces the density of states at the Fermi energy with respect to the pure ones. On the other hand, the small conductances of 0.3G{sub 0} (Rh) and 0.2G{sub 0} (Co) are due to H-decorated atomic chains connected to electrodes by a H atom.

  4. The unstoppable connexin43 carboxyl-terminus: new roles in gap junction organization and wound healing.

    Science.gov (United States)

    Gourdie, Robert G; Ghatnekar, Gautam S; O'Quinn, Michael; Rhett, Matthew J; Barker, Ralph J; Zhu, Ching; Jourdan, Jane; Hunter, Andrew W

    2006-10-01

    Intercellular connectivity mediated by gap junctions (GJs) composed of connexin43 (Cx43) is critical to the function of excitable tissues such as the heart and brain. Disruptions to Cx43 GJ organization are thought to be a factor in cardiac arrhythmias and are also implicated in epilepsy. This article is based on a presentation to the 4th Larry and Horti Fairberg Workshop on Interactive and Integrative Cardiology and summarizes the work of Gourdie and his lab on Cx43 GJs in the heart. Background and perspective of recently published studies on the function of Cx43-interacting protein zonula occludens-(ZO)-1 in determining the organization of GJ plaques are provided. In addition how a peptide containing a PDZ-binding sequence of Cx43, developed as part of the work on cardiac GJ organization is also described, which has led to evidence for novel and unexpected roles for Cx43 in modulating healing following tissue injury.

  5. Spin Seebeck effect in a metal-single-molecule-magnet-metal junction

    Directory of Open Access Journals (Sweden)

    Pengbin Niu

    2018-01-01

    Full Text Available We investigate the nonlinear regime of temperature-driven spin-related currents through a single molecular magnet (SMM, which is connected with two metal electrodes. Under a large spin approximation, the SMM is simplified to a natural two-channel model possessing spin-opposite configuration and Coulomb interaction. We find that in temperature-driven case the system can generate spin-polarized currents. More interestingly, at electron-hole symmetry point, the competition of the two channels induces a temperature-driven pure spin current. This device demonstrates that temperature-driven SMM junction shows some results different from the usual quantum dot model, which may be useful in the future design of thermal-based molecular spintronic devices.

  6. Ligament of Barkow of the craniocervical junction: its anatomy and potential clinical and functional significance.

    Science.gov (United States)

    Tubbs, R Shane; Dixon, Joshua; Loukas, Marios; Shoja, Mohammadali M; Cohen-Gadol, Aaron A

    2010-06-01

    Knowledge of the anatomy of the ligaments that unite the head with the neck is important to the clinician who treats patients with lesions in this region. Although the anatomy and function of these ligaments have been well described, those of the Barkow ligament (BL) have yet to be studied. Via an anterior approach, 13 unembalmed adult cadavers underwent dissection of the craniocervical junction with special attention to the presence, anatomy, and function of the BL. The BL was found in 92.3% of specimens. The attachment of each ligament onto the medial aspect of the occipital condyle was consistent and just anterior to the attachment of the alar ligaments. In 75% of specimens, there was some connection between the BL and the anterior atlantooccipital membrane. Connections between other adjacent ligamentous structures were not identified. The average width, length, and thickness of the BL were 4, 2.5, and 3.5 mm, respectively. With ranges of motion of the craniocervical junction, only extension of the atlantooccipital joint produced tension in the BL. The mean tension to failure of the ligament was 28 N. Statistical analysis revealed no significant difference in width, length, and thickness of the ligaments based on sex. The BL was found in all but 1 of our specimens. This ligament appears to resist extension of the atlantooccipital joint and may be synergistic with the anterior atlantooccipital membrane. Interestingly, the function of this ligament as found in this study relies on the integrity of the transverse ligament. Knowledge of this ligament may aid in further understanding craniocervical stability and help in differentiating normal from pathological tissue using imaging modalities.

  7. Connectivity and superconductivity

    CERN Document Server

    Rubinstein, Jacob

    2000-01-01

    The motto of connectivity and superconductivity is that the solutions of the Ginzburg--Landau equations are qualitatively influenced by the topology of the boundaries, as in multiply-connected samples. Special attention is paid to the "zero set", the set of the positions (also known as "quantum vortices") where the order parameter vanishes. The effects considered here usually become important in the regime where the coherence length is of the order of the dimensions of the sample. It takes the intuition of physicists and the awareness of mathematicians to find these new effects. In connectivity and superconductivity, theoretical and experimental physicists are brought together with pure and applied mathematicians to review these surprising results. This volume is intended to serve as a reference book for graduate students and researchers in physics or mathematics interested in superconductivity, or in the Schrödinger equation as a limiting case of the Ginzburg--Landau equations.

  8. Skeletal muscle connective tissue

    DEFF Research Database (Denmark)

    Brüggemann, Dagmar Adeline

    that collagen plays a significant role in determining the tenderness of meat. What are we missing? Therefore, fundamental aspects of connective tissue research have been the centre of attention throughout this thesis. A holistic view has been applied, glancing at this complex tissue which has many facets......  The connective tissue content of skeletal muscle is believed to be the major factor responsible for defining the eating quality of different meat cuts, although attempts to correlate quantifications based on traditional histological methods have not as yet been able to prove this relation....... Collagen, being the major protein in connective tissue, has been extensively investigated with regard to its relation to meat tenderness, but the results have been rather conflicting. Meat from older animals is tougher than that from younger animals, and changes in the properties of the collagen due...

  9. Graphene based superconducting junctions as spin sources for spintronics

    Science.gov (United States)

    Emamipour, Hamidreza

    2018-02-01

    We investigate spin-polarized transport in graphene-based ferromagnet-superconductor junctions within the Blonder-Tinkham-Klapwijk formalism by using spin-polarized Dirac-Bogoliubov-de-Gennes equations. We consider superconductor in spin-singlet s-wave pairing state and ferromagnet is modeled by an exchange field with energy of Ex. We have found that graphene-based junctions can be used to produce highly spin-polarized current in different situations. For example, if we design a junction with high Ex and EF compared to order parameter of superconductor, then one can have a large spin-polarized current which is tunable in magnitude and sign by bias voltage and Ex. Therefore graphene-based superconducting junction can be used in spintronic devices in alternative to conventional junctions or half-metallic ferromagnets. Also, we have found that the calculated spin polarization can be used as a tool to distinguish specular Andreev reflection (SAR) from the conventional Andreev reflection (CAR) such that in the case of CAR, spin polarization in sub-gap region is completely negative which means that spin-down current is greater than spin-up current. When the SAR is dominated, the spin polarization is positive at all bias-voltages, which itself shows that spin-up current is greater than spin-down current.

  10. Fibroepithelial polyps causing ureteropelvic junction obstruction in children.

    Science.gov (United States)

    Adey, Gregory S; Vargas, Sara O; Retik, Alan B; Borer, Joseph G; Mandell, James; Hendren, W Hardy; Lebowitz, Robert L; Bauer, Stuart B

    2003-05-01

    Fibroepithelial polyps are benign mucosal projections that can be found throughout the urinary system. We review our experience with fibroepithelial polyps of the ureteropelvic junction in children to define more clearly this entity and its outcome following treatment. We reviewed the records of all children with fibroepithelial polyps causing ureteropelvic junction obstruction treated at our institution between December 1967 and February 2002. Nine patients 6 weeks to 9 years old had 11 ureteropelvic junction obstructions secondary to fibroepithelial polyps, representing a 0.5% incidence of all ureteropelvic junction obstructions seen during that period. The majority of the patients were male (89%) and had obstruction on the left side (78%). Only 22% of the patients had a diagnosis of obstructing polyps suggested preoperatively. All patients underwent dismembered pyeloplasty but 1 required subsequent nephrectomy due to progressive loss of renal function. All lesions were characterized microscopically by polypoid projections of fibrous tissue covered by epithelium and demonstrating varying degrees of inflammation. No recurrences were seen during a mean followup of 44 months. Fibroepithelial polyps are rare lesions that cause ureteropelvic junction obstruction in children, primarily in males and on the left side. Filling defects were diagnosed preoperatively in 22% of the patients in this series. Excision and dismembered pyeloplasty were curative, and recurrences were not observed. The etiology of this disease remains obscure.

  11. Q factor and resonance amplitude of Josephson tunnel junctions

    International Nuclear Information System (INIS)

    Broom, R.F.; Wolf, P.

    1977-01-01

    The surface impedance of the superconducting films comprising the electrodes of Josephson tunnel junctions has been derived from the BCS theory in the extreme London limit. Expressions have been obtained for (i) the dependence of the penetration depth lambda on frequency and temperature, and (ii) the quality factor Q of the junction cavity, attributable to surface absorption in the electrodes. The effect of thin electrodes (t 9 or approx. = lambda) is also included in the calculations. Comparison of the calculated frequency dependence of lambda with resonance measurements on Pb-alloy and all-Nb tunnel junctions yields quite good agreement, indicating that the assumptions made in the theory are reasonable. Measurements of the (current) amplitude of the resonance peaks of the junctions have been compared with the values obtained from inclusion of the calculated Q in the theory by Kulik. In common with observations on microwave cavities by other workers, we find that a small residual conductivity must be added to the real part of the BCS value. With its inclusion, good agreement is found between calculation and experiment, within the range determined by the simplifying assumptions of Kulik's theory. From the results, we believe the calculation of Q to be reasonably accurate for the materials investigated. It is shown that the resonance amplitude of Josephson junctions can be calculated directly from the material constants and a knowledge of the residual conductivity

  12. Human zonulin, a potential modulator of intestinal tight junctions.

    Science.gov (United States)

    Wang, W; Uzzau, S; Goldblum, S E; Fasano, A

    2000-12-01

    Intercellular tight junctions are dynamic structures involved in vectorial transport of water and electrolytes across the intestinal epithelium. Zonula occludens toxin derived from Vibrio cholerae interacts with a specific intestinal epithelial surface receptor, with subsequent activation of a complex intracellular cascade of events that regulate tight junction permeability. We postulated that this toxin may mimic the effect of a functionally and immunologically related endogenous modulator of intestinal tight junctions. Affinity-purified anti-zonula occludens toxin antibodies and the Ussing chamber assay were used to screen for one or more mammalian zonula occludens toxin analogues in both fetal and adult human intestine. A novel protein, zonulin, was identified that induces tight junction disassembly in non-human primate intestinal epithelia mounted in Ussing chambers. Comparison of amino acids in the active zonula occludens toxin fragment and zonulin permitted the identification of the putative receptor binding domain within the N-terminal region of the two proteins. Zonulin likely plays a pivotal role in tight junction regulation during developmental, physiological, and pathological processes, including tissue morphogenesis, movement of fluid, macromolecules and leukocytes between the intestinal lumen and the interstitium, and inflammatory/autoimmune disorders.

  13. A First-Principle Theoretical Study of Mechanical and Electronic Properties in Graphene Single-Walled Carbon Nanotube Junctions

    Directory of Open Access Journals (Sweden)

    Ning Yang

    2017-11-01

    Full Text Available The new three-dimensional structure that the graphene connected with SWCNTs (G-CNTs, Graphene Single-Walled Carbon Nanotubes can solve graphene and CNTs′ problems. A comprehensive study of the mechanical and electrical performance of the junctions was performed by first-principles theory. There were eight types of junctions that were constituted by armchair and zigzag graphene and (3,3, (4,0, (4,4, and (6,0 CNTs. First, the junction strength was investigated. Generally, the binding energy of armchair G-CNTs was stronger than that of zigzag G-CNTs, and it was the biggest in the armchair G-CNTs (6,0. Likewise, the electrical performance of armchair G-CNTs was better than that of zigzag G-CNTs. Charge density distribution of G-CNTs (6,0 was the most homogeneous. Next, the impact factors of the electronic properties of armchair G-CNTs were investigated. We suggest that the band gap is increased with the length of CNTs, and its value should be dependent on the combined effect of both the graphene’s width and the CNTs’ length. Last, the relationship between voltage and current (U/I were studied. The U/I curve of armchair G-CNTs (6,0 possessed a good linearity and symmetry. These discoveries will contribute to the design and production of G-CNT-based devices.

  14. Infusion of gliotoxins or a gap junction blocker in the prelimbic cortex increases alcohol preference in Wistar rats.

    Science.gov (United States)

    Miguel-Hidalgo, J; Shoyama, Y; Wanzo, V

    2009-07-01

    Postmortem research has revealed that there is a lower density of glial cells in regions of the prefrontal cortex (PFC) of uncomplicated alcoholics when compared with control subjects. Impairment of astrocyte function in the PFC may contribute to malfunction in circuits involved in emotion- and reward-related subcortical centers, heavily connected with the PFC and directly involved in the pathophysiology of addictive behaviours. The hypothesis was tested that infusion of gliotoxins known to injure astrocytes or of a gap junction blocker into the prelimbic area of the rat PFC results in increased preference for ethanol in rats exposed to free choice between water and 10% ethanol. Fluorocitric acid, L-alpha-aminoadipic acid (AAD) or the gap junction blocker 18-alpha-glycyrrhetinic acid (AGA) were bilaterally infused once into the rat prelimbic cortex and alcohol preference (ratio of 10% ethanol consumed to total liquid ingested) was measured before and after infusion. Infusion of AAD or AGA dissolved in their vehicles, but not of their vehicles alone, resulted in significant transient increase of preference for 10% ethanol. The present data suggest that impaired integrity of glial cells or the gap junctional communication between them in the rat PFC may contribute to changes in ethanol preference.

  15. Best connected rectangular arrangements

    Directory of Open Access Journals (Sweden)

    Krishnendra Shekhawat

    2016-03-01

    Full Text Available It can be found quite often in the literature that many well-known architects have employed either the golden rectangle or the Fibonacci rectangle in their works. On contrary, it is rare to find any specific reason for using them so often. Recently, Shekhawat (2015 proved that the golden rectangle and the Fibonacci rectangle are one of the best connected rectangular arrangements and this may be one of the reasons for their high presence in architectural designs. In this work we present an algorithm that generates n-4 best connected rectangular arrangements so that the proposed solutions can be further used by architects for their designs.

  16. Connecting textual segments

    DEFF Research Database (Denmark)

    Brügger, Niels

    2017-01-01

    In “Connecting textual segments: A brief history of the web hyperlink” Niels Brügger investigates the history of one of the most fundamental features of the web: the hyperlink. Based on the argument that the web hyperlink is best understood if it is seen as another step in a much longer and broader...... history than just the years of the emergence of the web, the chapter traces the history of how segments of text have deliberately been connected to each other by the use of specific textual and media features, from clay tablets, manuscripts on parchment, and print, among others, to hyperlinks on stand...

  17. Multiple regions of Crumbs3 are required for tight junction formation in MCF10A cells.

    Science.gov (United States)

    Fogg, Vanessa C; Liu, Chia-Jen; Margolis, Ben

    2005-07-01

    The formation and maintenance of tight junctions is essential for the development of epithelial cell polarity. Recently, a number of conserved polarity-regulating proteins have been shown to localize to epithelial tight junctions, and to play a role in the regulation of tight junction formation. The Crumbs3/PALS1/PATJ protein complex localizes at epithelial tight junctions and interacts with the polarity-regulating protein complex of Par6/Par3/aPKC. Overexpression of Crumbs3 in MDCKII cells leads to a delay in tight junction formation in these cells, suggesting a role in the regulation of tight junction development. Here we report new evidence that Crumbs3 indeed plays an essential role in tight junction formation. Mammary MCF10A cells express little endogenous Crumbs3 and fail to form tight junctions when grown under standard tissue culture conditions. The staining pattern of ZO-1, a tight junction marker, is fragmented, and other tight junction markers show either fragmented junctional expression or diffuse cytoplasmic staining. Expression of exogenous Crumbs3 induces the formation of tight junction structures marked by smooth, continuous ZO-1 staining at apical cell-cell junctions. A number of other tight junction markers, including claudin-1 and occludin, are also recruited to these junctions. Analysis by transmission electron microscopy and measurements of the transepithelial electrical resistance confirm that these structures are functional tight junctions. Mutations in either the Crumbs3 PDZ binding motif or the putative FERM binding motif lead to defects in the ability of Crumbs3 to promote tight junction development. Our results suggest that Crumbs3 plays an important role in epithelial tight junction formation, and also provide the first known functional role for the mammalian Crumbs FERM binding domain.

  18. Superpoissonian shot noise in organic magnetic tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Cascales, Juan Pedro; Martinez, Isidoro; Aliev, Farkhad G., E-mail: farkhad.aliev@uam.es [Dpto. Fisica Materia Condensada C3, Instituto Nicolas Cabrera (INC), Condensed Matter Physics Institute (IFIMAC), Universidad Autonoma de Madrid, Madrid 28049 (Spain); Hong, Jhen-Yong; Lin, Minn-Tsong, E-mail: mtlin@phys.ntu.edu.tw [Department of Physics, National Taiwan University, Taipei 10617, Taiwan and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan (China); Szczepański, Tomasz; Dugaev, Vitalii K. [Department of Physics, Rzeszów University of Technology, al. Powstańców Warszawy 6, 35-959 Rzeszów (Poland); Barnaś, Józef [Faculty of Physics, Adam Mickiewicz University, ul. Umultowska 85, 61-614 Poznań, Poland and Institute of Molecular Physics, Polish Academy of Sciences, ul. Smoluchowskiego 17, 60-179 Poznań (Poland)

    2014-12-08

    Organic molecules have recently revolutionized ways to create new spintronic devices. Despite intense studies, the statistics of tunneling electrons through organic barriers remains unclear. Here, we investigate conductance and shot noise in magnetic tunnel junctions with 3,4,9,10-perylene-teracarboxylic dianhydride (PTCDA) barriers a few nm thick. For junctions in the electron tunneling regime, with magnetoresistance ratios between 10% and 40%, we observe superpoissonian shot noise. The Fano factor exceeds in 1.5–2 times the maximum values reported for magnetic tunnel junctions with inorganic barriers, indicating spin dependent bunching in tunneling. We explain our main findings in terms of a model which includes tunneling through a two level (or multilevel) system, originated from interfacial bonds of the PTCDA molecules. Our results suggest that interfaces play an important role in the control of shot noise when electrons tunnel through organic barriers.

  19. T-junctions and perceived slant of partially occluded surfaces.

    Science.gov (United States)

    Grove, Philip M; Ono, Hiroshi; Kaneko, Hirohiko

    2003-01-01

    Häkkinen and Nyman (1997 Perception 26 29-38) reported that perceived slant is reduced when occlusion is a possible interpretation for the visual system. We present data from three experiments that confirm and expand on their finding. Our stimuli consisted of four types of stereograms depicting white central rectangles flanked on either side by two grey rectangles. The central white rectangles varied in height, thus manipulating the polarity of the T-junction information between the central and flanking rectangles. Perceived slant was smallest or not apparent when T-junction information indicated the central rectangles were nearer than the flanking rectangles and greatest when T-junction information indicated a farther central rectangle. Slant estimates for a stimulus containing a subjective pacmen-induced central rectangle were biased towards a depth step when an occlusion interpretation was possible.

  20. Tuning spin transport across two-dimensional organometallic junctions

    Science.gov (United States)

    Liu, Shuanglong; Wang, Yun-Peng; Li, Xiangguo; Fry, James N.; Cheng, Hai-Ping

    2018-01-01

    We study via first-principles modeling and simulation two-dimensional spintronic junctions made of metal-organic frameworks consisting of two Mn-phthalocyanine ferromagnetic metal leads and semiconducting Ni-phthalocyanine channels of various lengths. These systems exhibit a large tunneling magnetoresistance ratio; the transmission functions of such junctions can be tuned using gate voltage by three orders of magnitude. We find that the origin of this drastic change lies in the orbital alignment and hybridization between the leads and the center electronic states. With physical insight into the observed on-off phenomenon, we predict a gate-controlled spin current switch based on two-dimensional crystallines and offer general guidelines for designing spin junctions using 2D materials.

  1. Robust spin transfer torque in antiferromagnetic tunnel junctions

    KAUST Repository

    Saidaoui, Hamed Ben Mohamed

    2017-04-18

    We theoretically study the current-induced spin torque in antiferromagnetic tunnel junctions, composed of two semi-infinite antiferromagnetic layers separated by a tunnel barrier, in both clean and disordered regimes. We find that the torque enabling electrical manipulation of the Néel antiferromagnetic order parameter is out of plane, ∼n×p, while the torque competing with the antiferromagnetic exchange is in plane, ∼n×(p×n). Here, p and n are the Néel order parameter direction of the reference and free layers, respectively. Their bias dependence shows behavior similar to that in ferromagnetic tunnel junctions, the in-plane torque being mostly linear in bias, while the out-of-plane torque is quadratic. Most importantly, we find that the spin transfer torque in antiferromagnetic tunnel junctions is much more robust against disorder than that in antiferromagnetic metallic spin valves due to the tunneling nature of spin transport.

  2. Single Molecule Junctions: Probing Contact Chemistry and Fundamental Circuit Laws

    Energy Technology Data Exchange (ETDEWEB)

    Hybertsen M. S.

    2013-04-11

    By exploiting selective link chemistry, formation of single molecule junctions with reproducible conductance has become established. Systematic studies reveal the structure-conductance relationships for diverse molecules. I will draw on experiments from my collaborators at Columbia University, atomic-scale calculations and theory to describe progress in two areas. First, I will describe a novel route to form single molecule junctions, based on SnMe3 terminated molecules, in which gold directly bonds to carbon in the molecule backbone resulting in near ideal contact resistance [1]. Second, comparison of the conductance of junctions formed with molecular species containing either one backbone or two backbones in parallel allows demonstration of the role of quantum interference in the conductance superposition law at the molecular scale [2].

  3. Fibroepithelial polyps causing ureteropelvic junction obstruction in a child.

    Science.gov (United States)

    Li, Wei-Ming; Wu, Wen-Jeng; Ke, Hung-Lung; Chai, Chee-Yin; Chou, Yii-Her; Huang, Chun-Hsiung

    2005-06-01

    Fibroepithelial polyps of the ureter are benign tumors arising from mesodermal tissue in the ureter wall. They are extremely rare lesions that can cause ureteropelvic junction obstruction in children. In this report, we describe an 11-year-old boy with fibroepithelial polyps of the ureter that caused left ureteropelvic junction obstruction. He presented with a 6-month history of left abdominal and flank pain. He also had short stature. Intravenous pyelography showed hydronephrosis without filling defects at the left ureteropelvic junction. Exploration revealed several finger-like polyps obstructing the lumen. This area was resected segmentally and a dismembered pyeloplasty was performed. No complications occurred during the postoperative period. The boy caught up in growth after the operation. Fibroepithelial polyps were confirmed by histology.

  4. Fibroepithelial Polyps Causing Ureteropelvic Junction Obstruction in a Child

    Directory of Open Access Journals (Sweden)

    Wei-Ming Li

    2005-06-01

    Full Text Available Fibroepithelial polyps of the ureter are benign tumors arising from mesodermal tissue in the ureter wall. They are extremely rare lesions that can cause ureteropelvic junction obstruction in children. In this report, we describe an 11-year-old boy with fibroepithelial polyps of the ureter that caused left ureteropelvic junction obstruction. He presented with a 6-month history of left abdominal and flank pain. He also had short stature. Intravenous pyelography showed hydronephrosis without filling defects at the left ureteropelvic junction. Exploration revealed several finger-like polyps obstructing the lumen. This area was resected segmentally and a dismembered pyeloplasty was performed. No complications occurred during the postoperative period. The boy caught up in growth after the operation. Fibroepithelial polyps were confirmed by histology.

  5. Reactive tunnel junctions in electrically driven plasmonic nanorod metamaterials

    Science.gov (United States)

    Wang, Pan; Krasavin, Alexey V.; Nasir, Mazhar E.; Dickson, Wayne; Zayats, Anatoly V.

    2018-02-01

    Non-equilibrium hot carriers formed near the interfaces of semiconductors or metals play a crucial role in chemical catalysis and optoelectronic processes. In addition to optical illumination, an efficient way to generate hot carriers is by excitation with tunnelling electrons. Here, we show that the generation of hot electrons makes the nanoscale tunnel junctions highly reactive and facilitates strongly confined chemical reactions that can, in turn, modulate the tunnelling processes. We designed a device containing an array of electrically driven plasmonic nanorods with up to 1011 tunnel junctions per square centimetre, which demonstrates hot-electron activation of oxidation and reduction reactions in the junctions, induced by the presence of O2 and H2 molecules, respectively. The kinetics of the reactions can be monitored in situ following the radiative decay of tunnelling-induced surface plasmons. This electrically driven plasmonic nanorod metamaterial platform can be useful for the development of nanoscale chemical and optoelectronic devices based on electron tunnelling.

  6. Bubbly flow pressure drop in a T junction

    International Nuclear Information System (INIS)

    Boulanger, Fabien

    1991-01-01

    This research thesis reports a theoretical and experimental study of pressure evolution in the singularity of a T junction carrying a bubbly flow. The various involved phenomena are studied in the case of a single-phase flow. Thus, within the heart of the junction, the detailed study of the energy assessment leads to a kinetic modelling of pressure variations. In downstream branches, an integral model allows the prediction of flow restoration. A systematic experimental validation has been performed by using a two-component laser anemometry system, and through the determination of pressure lines. Then, the study has been extended to the case of bubbly flows. Obtained results are compared with experimental values of pressure evolution. By associating a phase segregation existing model, the problem of a bubbly flow in a T junction is then fully addressed [fr

  7. Asthenospheric flow and lithospheric evolution near the Mendocino Triple Junction

    Science.gov (United States)

    Liu, Kaijian; Levander, Alan; Zhai, Yongbo; Porritt, Robert W.; Allen, Richard M.

    2012-03-01

    The migration of the Mendocino Triple Junction in northern California creates a complicated lithosphere-asthenosphere boundary system at shallow depths (Gorda plate, the joint inversion Vs model further identifies three other young asthenospheres resulting from different partial melting mechanisms. Northward motion of the triple junction causes asthenospheric flow both from under the Gorda plate and from the cooling former mantle wedge left under the Great Valley and Sierra Nevada, imaged from the joint inversion as a relatively deep (> 75 km) low-Vs anomaly. These two mantle flows appear to begin mixing ~ 100 km south of the southern edge of the Gorda plate in the slab window region. We speculate that the latter provides the wedge-type geochemical signature seen in the Coast Range volcanic rocks, reconciling slab window models and volcanic geochemistry. This 'staggered' upwelling model proposed here also explains the ~ 3 Myr delay in onset of volcanism after triple junction migration.

  8. Thermoelectric properties of graphene nanoribbons, junctions and superlattices.

    Science.gov (United States)

    Chen, Y; Jayasekera, T; Calzolari, A; Kim, K W; Nardelli, M Buongiorno

    2010-09-22

    Using model interaction Hamiltonians for both electrons and phonons and Green's function formalism for ballistic transport, we have studied the thermal conductance and the thermoelectric properties of graphene nanoribbons (GNR), GNR junctions and periodic superlattices. Among our findings we have established the role that interfaces play in determining the thermoelectric response of GNR systems both across single junctions and in periodic superlattices. In general, increasing the number of interfaces in a single GNR system increases the peak ZT values that are thus maximized in a periodic superlattice. Moreover, we proved that the thermoelectric behavior is largely controlled by the width of the narrower component of the junction. Finally, we have demonstrated that chevron-type GNRs recently synthesized should display superior thermoelectric properties.

  9. Traumatic Tear of the Latissimus Dorsi Myotendinous Junction

    Science.gov (United States)

    Friedman, Michael V.; Stensby, J. Derek; Hillen, Travis J.; Demertzis, Jennifer L.; Keener, Jay D.

    2015-01-01

    A case of a latissimus dorsi myotendinous junction strain in an avid CrossFit athlete is presented. The patient developed acute onset right axillary burning and swelling and subsequent palpable pop with weakness while performing a “muscle up.” Magnetic resonance imaging examination demonstrated a high-grade tear of the right latissimus dorsi myotendinous junction approximately 9 cm proximal to its intact humeral insertion. There were no other injuries to the adjacent shoulder girdle structures. Isolated strain of the latissimus dorsi myotendinous junction is a very rare injury with a scarcity of information available regarding its imaging appearance and preferred treatment. This patient was treated conservatively and was able to resume active CrossFit training within 3 months. At 6 months postinjury, he had only a mild residual functional deficit compared with his preinjury level. PMID:26502450

  10. Breaking gold nano-junctions simulation and analysis

    DEFF Research Database (Denmark)

    Lauritzen, Kasper Primdal

    Simulating the movements of individual atoms allows us to look at and investigate the physical processes that happen in an experiment. In this thesis I use simulations to support and improve experimental studies of breaking gold nano-junctions. By using molecular dynamics to study gold nanowires, I...... can investigate their breaking forces under varying conditions, like stretching rate or temperature. This resolves a confusion in the literature, where the breaking forces of two different breaking structures happen to coincide. The correlations between the rupture and reformation of a gold junction......, to predict the structure of a gold junction just as it breaks. This method is based on artificial neural networks and can be used on experimental data, even when it is trained purely on simulated data. The method is extended to other types of experimental traces, where it is trained without the use...

  11. Precision control of single-molecule electrical junctions.

    Science.gov (United States)

    Haiss, Wolfgang; Wang, Changsheng; Grace, Iain; Batsanov, Andrei S; Schiffrin, David J; Higgins, Simon J; Bryce, Martin R; Lambert, Colin J; Nichols, Richard J

    2006-12-01

    There is much discussion of molecules as components for future electronic devices. However, the contacts, the local environment and the temperature can all affect their electrical properties. This sensitivity, particularly at the single-molecule level, may limit the use of molecules as active electrical components, and therefore it is important to design and evaluate molecular junctions with a robust and stable electrical response over a wide range of junction configurations and temperatures. Here we report an approach to monitor the electrical properties of single-molecule junctions, which involves precise control of the contact spacing and tilt angle of the molecule. Comparison with ab initio transport calculations shows that the tilt-angle dependence of the electrical conductance is a sensitive spectroscopic probe, providing information about the position of the Fermi energy. It is also shown that the electrical properties of flexible molecules are dependent on temperature, whereas those of molecules designed for their rigidity are not.

  12. The distribution of work performed on a NIS junction

    DEFF Research Database (Denmark)

    Santos, Jaime Eduardo Vieira da Silva Moutinho; Ribeiro, Pedro; Kirchner, Stefan

    2016-01-01

    results are based on an equivalence between the dynamics of the NIS junction and that of an assembly of two-level systems subjected to a circularly polarised field, for which we can determine the work-characteristic function exactly. The average work dissipated by the NIS junction, as well as its...... fluctuations, are determined. From the work characteristic function, we also compute the work probability-distribution and show that it does not have a Gaussian character. Our results allow for a direct experimental test of the Crooks–Tasaki fluctuation relation.......We propose an experimental setup to measure the work performed in a normal-metal/insulator/superconducting (NIS) junction, subjected to a voltage change and in contact with a thermal bath. We compute the performed work and argue that the associated heat release can be measured experimentally. Our...

  13. Magnetic properties of slablike Josephson-junction arrays

    International Nuclear Information System (INIS)

    Chen, D.; Sanchez, A.; Hernando, A.

    1994-01-01

    Magnetic properties of infinitely long and wide slablike Josephson-junction arrays (JJA's) consisting of 2N+1 rows of grains are calculated for the dc Josephson effect with gauge-invariant phase differences. When N is large, the intergranular magnetization curve, M J (H), of the JJA's in low fields approaches that of uniform Josephson junctions with lengths equal to the thicknesses of the JJA's, but in a larger field interval, its amplitude is dually modulated with periods determined by the junction and void areas. M J (H) curves for small N are more complicated. The concept of Josephson vortices and the application of the results to high-T c superconductors are discussed

  14. Josephson radiation and shot noise of a semiconductor nanowire junction

    Science.gov (United States)

    van Woerkom, David J.; Proutski, Alex; van Gulik, Ruben J. J.; Kriváchy, Tamás; Car, Diana; Plissard, Sébastian R.; Bakkers, Erik P. A. M.; Kouwenhoven, Leo P.; Geresdi, Attila

    2017-09-01

    We measured the Josephson radiation emitted by an InSb semiconductor nanowire junction utilizing photon-assisted quasiparticle tunneling in an ac-coupled superconducting tunnel junction. We quantify the action of the local microwave environment by evaluating the frequency dependence of the inelastic Cooper-pair tunneling of the nanowire junction and find the zero-frequency impedance Z (0 )=492 Ω with a cutoff frequency of f0=33.1 GHz . We extract a circuit coupling efficiency of η ≈0.1 and a detector quantum efficiency approaching unity in the high-frequency limit. In addition to the Josephson radiation, we identify a shot noise contribution with a Fano factor F ≈1 , consistently with the presence of single electron states in the nanowire channel.

  15. Nanotube junctions and the genus of multi-tori.

    Science.gov (United States)

    Diudea, Mircea V; Szefler, Beata

    2012-06-14

    Carbon nanotube junctions can be modeled by fullerene spanning or by using some operations on map. They can self-assemble into more complex structures, such as finite or infinite high genera multi-tori. Four junctions of tetrahedral and octahedral symmetry, covered by patches consisting only of hexagons, were designed. Their stability is discussed in terms of total energy, evaluated at Hartree-Fock (HF) level of theory, HOMO-LUMO gap, strain energy, HOMA index of aromaticity and the Kekulé structure count. Vibrational spectra of these junctions are given as well. A new multi-toroidal structure, of octahedral symmetry, is presented for the first time. The study on topology of the multi-tori herein designed revealed the relation of these structures with the genus of their embedding surface.

  16. Electrochemically assisted mechanically controllable break junction studies on the stacking configurations of oligo(phenylene ethynylene)s molecular junctions

    International Nuclear Information System (INIS)

    Zheng, Jue-Ting; Yan, Run-Wen; Tian, Jing-Hua; Liu, Jun-Yang; Pei, Lin-Qi; Wu, De-Yin; Dai, Ke; Yang, Yang; Jin, Shan

    2016-01-01

    Highlights: • I-V characteristics of a series of oligo(phenylene ethynylene)s molecular junctions were measured. • Conductance values were found to be dependent on molecular length and substituent group. • The measured low conductance values were explained by theoretical calculations. • EC-MCBJ is feasible to fabricate and characterize molecular junctions. - Abstract: We demonstrate an electrochemically assisted mechanically controllable break junction (EC-MCBJ) approach for current-voltage characteristic (I-V curve) measurements of metal/molecule/metal junctions. A series of oligo(phenylene ethynylene)s compounds (OPEs), including those involving electron withdrawing substituent group and different backbone lengths, had been successfully designed, synthesized, and placed onto the fabricated nanogap to form molecular junctions. The observed evolution in the measured conductances of OPEs indicates that there is a dependence of conductance on molecular length and substituent group. Compared with those extracted from conductance histogram construction, the conductances of OPEs measured from I-V curves are considerably lower. Based on the transmission spectra of OPEs that calculated by density functional theory (DFT) combined with non-equilibrium Green’s function (NEGF) method, this difference was attributed to our distinct experimental operation, which may give rise to a stacking configuration of two OPE molecules.

  17. Revisiting city connectivity

    NARCIS (Netherlands)

    Mans, U.

    2014-01-01

    This article introduces a new perspective on city connectivity in order to analyze non-hub cities and their position in the world economy. The author revisits the different approaches discussed in the Global Commodity Chains (GCC), Global Production Networks (GPN) and World City Network (WCN)

  18. Mathematics Connection: Editorial Policies

    African Journals Online (AJOL)

    MATHEMATICS CONNECTION aims at providing a forum to promote the development of Mathematics Education in Ghana. Articles that seek to enhance the teaching and/or learning of mathematics ... Faculty of Social Sciences, Methodist University, Accra Prof. B. K. Gordor, Department of Mathematics (UCC), Cape Coast ...

  19. IDRC Connect User Guide

    International Development Research Centre (IDRC) Digital Library (Canada)

    Kristina Kamichaitis

    IDRC believes that publicly funded research should be freely and openly available. We also believe that open access research facilitates access to knowledge world-wide. Open access is critical to empowerment through knowledge. IDRC Connect helps realize IDRC's Open Access Policy by facilitating the timely ...

  20. The connected brain

    NARCIS (Netherlands)

    van den Heuvel, M.P.

    2009-01-01

    The connected brain Martijn van den Heuvel, 2009 Our brain is a network. It is a network of different brain regions that are all functionally and structurally linked to each other. In the past decades, neuroimaging studies have provided a lot of information about the specific functions of each

  1. A Connective Pedagogy.

    Science.gov (United States)

    Goral, Mary

    2000-01-01

    Our increasingly hurried lifestyle, changes in family structure, and intense economic pressures place stress on children and families. Waldorf education provides an educational environment that alleviates this stress through a connective pedagogy that encompasses continuity of people, curriculum, and instruction; a reverence and respect for the…

  2. Mapping functional connectivity

    Science.gov (United States)

    Peter Vogt; Joseph R. Ferrari; Todd R. Lookingbill; Robert H. Gardner; Kurt H. Riitters; Katarzyna Ostapowicz

    2009-01-01

    An objective and reliable assessment of wildlife movement is important in theoretical and applied ecology. The identification and mapping of landscape elements that may enhance functional connectivity is usually a subjective process based on visual interpretations of species movement patterns. New methods based on mathematical morphology provide a generic, flexible,...

  3. From connection to customer

    International Nuclear Information System (INIS)

    Milatz, H.; Soeters, R.

    2001-01-01

    Energy companies can no longer be certain that a customer today will remain a customer tomorrow. They have to work hard to achieve that. They are going from thinking in terms of connections to pampering their customers. Good Customer Relationship Management is a way to achieve a competitive advantage. The whole organisation has to adapt, particularly the customer orientation of employees

  4. Connected vehicle application : safety.

    Science.gov (United States)

    2015-01-01

    Connected vehicle safety applications are designed to increase situational awareness : and reduce or eliminate crashes through vehicle-to-infrastructure (V2I), vehicle-to-vehicle (V2V), and vehicle-to-pedestrian (V2P) data transmissions. Applications...

  5. Clip, connect, clone

    DEFF Research Database (Denmark)

    Fujima, Jun; Lunzer, Aran; Hornbæk, Kasper

    2010-01-01

    using three mechanisms: clipping of input and result elements from existing applications to form cells on a spreadsheet; connecting these cells using formulas, thus enabling result transfer between applications; and cloning cells so that multiple requests can be handled side by side. We demonstrate...

  6. IDRC Connect User Guide

    International Development Research Centre (IDRC) Digital Library (Canada)

    Kristina Kamichaitis

    2 Jul 2015 ... olvide su nombre de usuario o la URL de IDRC Connect, o en caso de que necesite restablecer su ... El líder del proyecto es responsable de solicitar las cuentas del usuario para los miembros del Equipo del proyecto. ..... aparecerían en una cita, por ejemplo, "Universidad de Ottawa, Grupo de Estudios de.

  7. Connectivity measures: a review

    Czech Academy of Sciences Publication Activity Database

    Kindlmann, Pavel; Burel, F.

    2008-01-01

    Roč. 23, č. 1 (2008), s. 879-890 ISSN 0921-2973 R&D Projects: GA MŠk LC06073; GA AV ČR(CZ) IAA6087301 Institutional research plan: CEZ:AV0Z60870520 Keywords : Conservation biology * Habitat fragmentation * Landscape connectivity * Measures * Species extinction Subject RIV: EH - Ecology, Behaviour Impact factor: 2.453, year: 2008

  8. Mixed Connective Tissue Disease

    Science.gov (United States)

    ... complicated. Early signs and symptoms often involve the hands. Fingers might swell like sausages, and the fingertips become white and numb. In later stages, some organs — such as the lungs, heart and kidneys — may be affected. There's no cure for mixed connective tissue disease. The signs and ...

  9. Environmental Audit of the Grand Junction Projects Office

    Energy Technology Data Exchange (ETDEWEB)

    1991-08-01

    The Grand Junction Projects Office (GJPO) is located in Mesa County, Colorado, immediately south and west of the Grand Junction city limits. The US Atomic Energy Commission (AEC) established the Colorado Raw Materials Office at the present-day Grand Junction Projects Office in 1947, to aid in the development of a viable domestic uranium industry. Activities at the site included sampling uranium concentrate; pilot-plant milling research, including testing and processing of uranium ores; and operation of a uranium mill pilot plant from 1954 to 1958. The last shipment of uranium concentrate was sent from GJPO in January, 1975. Since that time the site has been utilized to support various DOE programs, such as the former National Uranium Resource Evaluation (NURE) Program, the Uranium Mill Tailings Remedial Action Project (UMTRAP), the Surplus Facilities Management Program (SFMP), and the Technical Measurements Center (TMC). All known contamination at GJPO is believed to be the result of the past uranium milling, analyses, and storage activities. Hazards associated with the wastes impounded at GJPO include surface and ground-water contamination and potential radon and gamma-radiation exposure. This report documents the results of the Baseline Environmental Audit conducted at Grand Junction Projects Office (GJPO) located in Grand Junction, Colorado. The Grand Junction Baseline Environmental Audit was conducted from May 28 to June 12, 1991, by the Office of Environmental Audit (EH-24). This Audit evaluated environmental programs and activities at GJPO, as well as GJPO activities at the State-Owned Temporary Repository. 4 figs., 12 tabs.

  10. Roles of gap junctions, connexins and pannexins in epilepsy

    Directory of Open Access Journals (Sweden)

    Shanthini eMylvaganam

    2014-05-01

    Full Text Available Enhanced gap junctional communication (GJC between neurons is considered a major factor underlying the neuronal synchrony driving seizure activity. In addition, the hippocampal sharp wave ripple complexes, associated with learning and seizures, are diminished by GJC blocking agents. Although gap junctional blocking drugs inhibit experimental seizures, they all have other nonspecific actions. Besides interneuronal GJC between dendrites, inter-axonal and inter-glial GJC is also considered important for seizure generation. Interestingly, in most studies of cerebral tissue from animal seizure models and from human patients with epilepsy, there is up-regulation of glial, but not neuronal gap junctional mRNA and protein. Significant changes in the expression and post-translational modification of the astrocytic connexin Cx43, and Panx1 were observed in an in vitro Co++ seizure model, further supporting a role for glia in seizure-genesis, although the reasons for this remain unclear. Further suggesting an involvement of astrocytic GJC in epilepsy, is the fact that the expression of astrocytic Cx mRNAs (Cxs 30 and 43 is several fold higher than that of neuronal Cx mRNAs (Cxs 36 and 45, and the number of glial cells outnumber neuronal cells in mammalian hippocampal and cortical tissue. Pannexin expression is also increased in both animal and human epileptic tissues. Specific Cx43 mimetic peptides, Gap 27 and SLS, inhibit the docking of astrocytic connexin Cx43 proteins from forming intercellular gap junctions, diminishing spontaneous seizures. Besides GJs, Cx membrane hemichannels in glia and Panx membrane channels in neurons and glia are also inhibited by gap junctional pharmacological blockers. Although there is no doubt that connexin-based gap junctions and hemichannels, and pannexin-based membrane channels are related to epilepsy, the specific details of how they are involved and how we can modulate their function for therapeutic purposes remain to

  11. Environmental Audit of the Grand Junction Projects Office

    International Nuclear Information System (INIS)

    1991-08-01

    The Grand Junction Projects Office (GJPO) is located in Mesa County, Colorado, immediately south and west of the Grand Junction city limits. The US Atomic Energy Commission (AEC) established the Colorado Raw Materials Office at the present-day Grand Junction Projects Office in 1947, to aid in the development of a viable domestic uranium industry. Activities at the site included sampling uranium concentrate; pilot-plant milling research, including testing and processing of uranium ores; and operation of a uranium mill pilot plant from 1954 to 1958. The last shipment of uranium concentrate was sent from GJPO in January, 1975. Since that time the site has been utilized to support various DOE programs, such as the former National Uranium Resource Evaluation (NURE) Program, the Uranium Mill Tailings Remedial Action Project (UMTRAP), the Surplus Facilities Management Program (SFMP), and the Technical Measurements Center (TMC). All known contamination at GJPO is believed to be the result of the past uranium milling, analyses, and storage activities. Hazards associated with the wastes impounded at GJPO include surface and ground-water contamination and potential radon and gamma-radiation exposure. This report documents the results of the Baseline Environmental Audit conducted at Grand Junction Projects Office (GJPO) located in Grand Junction, Colorado. The Grand Junction Baseline Environmental Audit was conducted from May 28 to June 12, 1991, by the Office of Environmental Audit (EH-24). This Audit evaluated environmental programs and activities at GJPO, as well as GJPO activities at the State-Owned Temporary Repository. 4 figs., 12 tabs

  12. Hyperglycaemia and diabetes impair gap junctional communication among astrocytes.

    Science.gov (United States)

    Gandhi, Gautam K; Ball, Kelly K; Cruz, Nancy F; Dienel, Gerald A

    2010-03-15

    Sensory and cognitive impairments have been documented in diabetic humans and animals, but the pathophysiology of diabetes in the central nervous system is poorly understood. Because a high glucose level disrupts gap junctional communication in various cell types and astrocytes are extensively coupled by gap junctions to form large syncytia, the influence of experimental diabetes on gap junction channel-mediated dye transfer was assessed in astrocytes in tissue culture and in brain slices from diabetic rats. Astrocytes grown in 15-25 mmol/l glucose had a slow-onset, poorly reversible decrement in gap junctional communication compared with those grown in 5.5 mmol/l glucose. Astrocytes in brain slices from adult STZ (streptozotocin)-treated rats at 20-24 weeks after the onset of diabetes also exhibited reduced dye transfer. In cultured astrocytes grown in high glucose, increased oxidative stress preceded the decrement in dye transfer by several days, and gap junctional impairment was prevented, but not rescued, after its manifestation by compounds that can block or reduce oxidative stress. In sharp contrast with these findings, chaperone molecules known to facilitate protein folding could prevent and rescue gap junctional impairment, even in the presence of elevated glucose level and oxidative stress. Immunostaining of Cx (connexin) 43 and 30, but not Cx26, was altered by growth in high glucose. Disruption of astrocytic trafficking of metabolites and signalling molecules may alter interactions among astrocytes, neurons and endothelial cells and contribute to changes in brain function in diabetes. Involvement of the microvasculature may contribute to diabetic complications in the brain, the cardiovascular system and other organs.

  13. Two dimensional imaging by series-connected STJs with sapphire absorber

    CERN Document Server

    Kushino, A; Yamasaki, N Y; Ohashi, T; Kurakado, M

    2002-01-01

    The position determination capability of the series-connected superconducting tunnel junctions (STJs) with Nb/Al/AlO sub x /Al/Nb junctions as a radiation detector is reported. Four groups of series-connected STJs are fabricated on a single crystal of sapphire substrate surrounding 3.5x3.5 mm sup 2 detection area. The signals detected by two STJs with 1.5 mm separation give a time delay caused by the propagation of phonons, and this enables us to measure the irradiated position. Using alpha-particles of 5.5 MeV, we clearly distinguished the incident positions with a potential resolution of 0.16+-0.07 mm (FWHM). Directional dependence in the phonon propagation in the sapphire substrate is not detected.

  14. Superconducting Coset Topological Fluids in Josephson Junction Arrays

    CERN Document Server

    Diamantini, M C; Trugenberger, C A; Sodano, Pasquale; Trugenberger, Carlo A.

    2006-01-01

    We show that the superconducting ground state of planar Josephson junction arrays is a P- and T-invariant coset topological quantum fluid whose topological order is characterized by the degeneracy 2 on the torus. This new mechanism for planar superconductivity is the P- and T-invariant analogue of Laughlin's quantum Hall fluids. The T=0 insulator-superconductor quantum transition is a quantum critical point characterized by gauge fields and deconfined degrees of freedom. Experiments on toroidal Josephson junction arrays could provide the first direct evidence for topological order and superconducting quantum fluids.

  15. Spin transport in spin filtering magnetic tunneling junctions.

    Science.gov (United States)

    Li, Yun; Lee, Eok Kyun

    2007-11-01

    Taking into account spin-orbit coupling and s-d interaction, we investigate spin transport properties of the magnetic tunneling junctions with spin filtering barrier using Landauer-Büttiker formalism implemented with the recursive algorithm to calculate the real-space Green function. We predict completely different bias dependence of negative tunnel magnetoresistance (TMR) between the systems composed of nonmagnetic electrode (NM)/ferromagnetic barrier (FB)/ferromagnet (FM) and NM/FB/FM/NM spin filtering tunnel junctions (SFTJs). Analyses of the results provide us possible ways of designing the systems which modulate the TMR in the negative magnetoresistance regime.

  16. Spin-filtering junctions with double ferroelectric barriers

    International Nuclear Information System (INIS)

    Yan, Ju; Ding-Yu, Xing

    2009-01-01

    An FS/FE/NS/FE/FS double tunnel junction is suggested to have the ability to inject, modulate and detect the spin-polarized current electrically in a single device, where FS is the ferromagnetic semiconductor electrode, NS is the nonmagnetic semiconductor, and FE the ferroelectric barrier. The spin polarization of the current injected into the NS region can be switched between a highly spin-polarized state and a spin unpolarized state. The high spin polarization may be detected by measuring the tunneling magnetoresistance ratio of the double tunnel junction

  17. Josephson junction analog and quasiparticle-pair current

    DEFF Research Database (Denmark)

    Bak, Christen Kjeldahl; Pedersen, Niels Falsig

    1973-01-01

    A close analogy exists between a Josephson junction and a phase-locked loop. A new type of electrical analog based on this principle is presented. It is shown that the inclusion in this analog of a low-pass filter gives rise to a current of the same form as the Josephson quasiparticle-pair curren....... A simple picture of the quasiparticle-pair current, which gives the right dependences, is obtained by assuming a junction cutoff frequency to be at the energy gap. ©1973 American Institute of Physics...

  18. Ferroelectric tunnel junctions for information storage and processing.

    Science.gov (United States)

    Garcia, Vincent; Bibes, Manuel

    2014-07-24

    Computer memory that is non-volatile and therefore able to retain its information even when switched off enables computers that do not need to be booted up. One of the technologies for such applications is ferroelectric random access memories, where information is stored as ferroelectric polarization. To miniaturize such devices to the size of a few nanometres, ferroelectric tunnel junctions have seen considerable interest. There, the electric polarization determines the electrical resistance of these thin films, switching the current on and off. With control over other parameters such as magnetism also being possible, ferroelectric tunnel junctions represent a promising and flexible device design.

  19. Phase transition in a modified square Josephson-junction array

    CERN Document Server

    Han, J

    1999-01-01

    We study the phase transition in a modified square proximity-coupled Josephson-junction array with small superconducting islands at the center of each plaquette. We find that the modified square array undergoes a Kosterlitz-Thouless-Berezinskii-like phase transition, but at a lower temperature than the simple square array with the same single-junction critical current. The IV characteristics, as well as the phase transition, resemble qualitatively those of a disordered simple square array. The effects of the presence of the center islands in the modified square array are discussed.

  20. Quantum fluctuations and the single-junction Coulomb blockade

    Energy Technology Data Exchange (ETDEWEB)

    Girvin, S.M. (Department of Physics, Indiana University, Bloomington, IN (USA)); Glazman, L.I. (Institute of Microelectronics Technology and High Purity Materials, U.S.S.R. Academy of Science, Moscow District (U.S.S.R.)); Jonson, M. (Solid State Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN (USA)); Penn, D.R.; Stiles, M.D. (National Institute of Standards and Technology, Gaithersburg, MD (USA))

    1990-06-25

    We investigate the effect of quantum fluctuations on the Coulomb blockade in a single tunnel junction coupled to its environment by a transmission line of arbitrary impedance {ital Z}({omega}). The quantized oscillation modes of the transmission line are suddenly displaced when an electron tunnels through the junction. For small {ital Z} (relative to the quantum of resitance), a weak power-law zero-bias anomaly occurs associated with the infrared-divergent shakeup of low-frequency transmission-line modes. For large {ital Z}, the full blockade is recovered. Comparison with recent experiments is made.

  1. Method for manufacturing nuclear radiation detector with deep diffused junction

    International Nuclear Information System (INIS)

    Hall, R.N.

    1977-01-01

    Germanium radiation detectors are manufactured by diffusing lithium into high purity p-type germanium. The diffusion is most readily accomplished from a lithium-lead-bismuth alloy at approximately 430 0 C and is monitored by a quartz half cell containing a standard composition of this alloy. Detectors having n-type cores may be constructed by converting high purity p-type germanium to n-type by a lithium diffusion and subsequently diffusing some of the lithium back out through the surface to create a deep p-n junction. Production of coaxial germanium detectors comprising deep p-n junctions by the lithium diffusion process is described

  2. A gallium phosphide high-temperature bipolar junction transistor

    Science.gov (United States)

    Zipperian, T. E.; Dawson, L. R.; Chaffin, R. J.

    1981-01-01

    Preliminary results are reported on the development of a high temperature (350 C) gallium phosphide bipolar junction transistor (BJT) for geothermal and other energy applications. This four-layer p(+)n(-)pp(+) structure was formed by liquid phase epitaxy using a supercooling technique to insure uniform nucleation of the thin layers. Magnesium was used as the p-type dopant to avoid excessive out-diffusion into the lightly doped base. By appropriate choice of electrodes, the device may also be driven as an n-channel junction field-effect transistor. The initial design suffers from a series resistance problem which limits the transistor's usefulness at high temperatures.

  3. Junction leakage measurements with micro four-point probes

    DEFF Research Database (Denmark)

    Lin, Rong; Petersen, Dirch Hjorth; Wang, Fei

    2012-01-01

    We present a new, preparation-free method for measuring the leakage current density on ultra-shallow junctions. The junction leakage is found by making a series of four-point sheet resistance measurements on blanket wafers with variable electrode spacings. The leakage current density is calculated...... using a fit of the measured four-point resistances to an analytical two-sheet model. The validity of the approximation involved in the two-sheet model is verified by a comparison to finite element model calculations....

  4. Conductance of Graphene Nanoribbon Junctions and the Tight Binding Model

    Directory of Open Access Journals (Sweden)

    Wu Y

    2011-01-01

    Full Text Available Abstract Planar carbon-based electronic devices, including metal/semiconductor junctions, transistors and interconnects, can now be formed from patterned sheets of graphene. Most simulations of charge transport within graphene-based electronic devices assume an energy band structure based on a nearest-neighbour tight binding analysis. In this paper, the energy band structure and conductance of graphene nanoribbons and metal/semiconductor junctions are obtained using a third nearest-neighbour tight binding analysis in conjunction with an efficient nonequilibrium Green's function formalism. We find significant differences in both the energy band structure and conductance obtained with the two approximations.

  5. Studies of Au/SAMs/PEDOT-PSS/Au tunnel junctions

    Science.gov (United States)

    Sun, Nan; Lieberman, Marya; Ruggiero, Steven

    2008-03-01

    We report on tunneling through thin organic films. Junctions of the form: Au/SAMs/Polymer/Au were prepared on electronic-grade Si substrates with Self-Assembled Monolayers (SAMs) including octanedithiol (HS-C8H16-SH) and mercaptohexadecanoic (HS-C15H30-COOH). A transitional conducting polymer film PEDOT-PSS was spun on to the SAMs layer, and junctions were completed with a gold film. X-ray photoelectron spectroscopy (XPS) was employed to monitor the quality of the SAMs films. The electron tunneling properties including dI/dV and d^2I/dV^2 versus bias for the SAMs are discussed.

  6. Electrical gating and rectification in graphene three-terminal junctions

    Energy Technology Data Exchange (ETDEWEB)

    Händel, B. [FG Nanotechnologie, Institut für Mikro- und Nanotechnologien MacroNano and Institut für Mikro- und Nanoelektronik, Postfach 100565, 98684 Ilmenau (Germany); FG Festkörperelektronik, Institut für Mikro- und Nanotechnologien MacroNano and Institut für Mikro- und Nanoelektronik, Technische Universität Ilmenau, Postfach 100565, 98684 Ilmenau (Germany); Hähnlein, B. [FG Nanotechnologie, Institut für Mikro- und Nanotechnologien MacroNano and Institut für Mikro- und Nanoelektronik, Postfach 100565, 98684 Ilmenau (Germany); Göckeritz, R. [FG Nanostrukturierte Materialien, Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 3, 06120 Halle (Saale) (Germany); Schwierz, F. [FG Festkörperelektronik, Institut für Mikro- und Nanotechnologien MacroNano and Institut für Mikro- und Nanoelektronik, Technische Universität Ilmenau, Postfach 100565, 98684 Ilmenau (Germany); Pezoldt, J., E-mail: joerg.pezoldt@tu-ilmenau.de [FG Nanotechnologie, Institut für Mikro- und Nanotechnologien MacroNano and Institut für Mikro- und Nanoelektronik, Postfach 100565, 98684 Ilmenau (Germany)

    2014-02-01

    Graphene was grown on semiinsulating silicon carbide at 1800 °C and atmospheric argon pressure. The all carbon T- and Y-shape three terminal junction devices were fabricated using electron beam lithography. All devices featured the negative rectification effect. The exact properties of the devices like the curvature of the output voltage response can be tuned by changing the branch width in the T- and Y-shape devices. Beside the rectification a switching behavior is demonstrated with the same three terminal junctions.

  7. Normal-metal-superconductor tunnel junction as a Brownian refrigerator.

    Science.gov (United States)

    Pekola, J P; Hekking, F W J

    2007-05-25

    Thermal noise generated by a hot resistor (resistance R) can, under proper conditions, catalyze heat removal from a cold normal metal (N) in contact with a superconductor (S) via a tunnel barrier (I). Such a NIS junction is reminiscent of Maxwell's demon, rectifying the heat flow. Upon reversal of the temperature gradient between the resistor and the junction, the heat fluxes are reversed: this presents a regime which is not accessible in an ordinary voltage-biased NIS structure. We obtain analytical results for the cooling performance in an idealized high impedance environment and perform numerical calculations for general R. We conclude by assessing the experimental feasibility of the proposed effect.

  8. Nonlinear electrical properties of Si three-terminal junction devices

    DEFF Research Database (Denmark)

    Fantao, Meng; Jie, Sun; Graczyk, Mariusz

    2010-01-01

    This letter reports on the realization and characterization of silicon three-terminal junction devices made in a silicon-on-insulator wafer. Room temperature electrical measurements show that the fabricated devices exhibit pronounced nonlinear electrical properties inherent to ballistic electron...... transport in a three-terminal ballistic junction (TBJ) device. The results show that room temperature functional TBJ devices can be realized in a semiconductor material other than high-mobility III-V semiconductor heterostructures and provide a simple design principle for compact silicon devices...

  9. Charging effects in the inductively shunted Josephson junction.

    Science.gov (United States)

    Koch, Jens; Manucharyan, V; Devoret, M H; Glazman, L I

    2009-11-20

    The choice of impedance used to shunt a Josephson junction determines if the charge transferred through the circuit is quantized: a capacitive shunt renders the charge discrete, whereas an inductive shunt gives continuous charge. This discrepancy leads to a paradox in the limit of large inductances L. We show that while the energy spectra of the capacitively and inductively shunted junction are vastly different, their high-frequency responses become identical for large L. Inductive shunting thus opens the possibility to observe charging effects unimpeded by charge noise.

  10. Skeletal muscle connective tissue

    DEFF Research Database (Denmark)

    Brüggemann, Dagmar Adeline

      The connective tissue content of skeletal muscle is believed to be the major factor responsible for defining the eating quality of different meat cuts, although attempts to correlate quantifications based on traditional histological methods have not as yet been able to prove this relation...... that collagen plays a significant role in determining the tenderness of meat. What are we missing? Therefore, fundamental aspects of connective tissue research have been the centre of attention throughout this thesis. A holistic view has been applied, glancing at this complex tissue which has many facets...... in this thesis that alpha-ketoglutarate, a tricarboxylic acid cycle metabolite, has the potential to control the metabolism of this particular tissue. Finally, a new microscopic method is introduced which allows the study of thermal denaturation of fibrillar collagen and myofibers in real time without any label...

  11. Connecting the Production Multiple

    DEFF Research Database (Denmark)

    Lichen, Alex Yu; Mouritsen, Jan

    was implementing sales and operations planning (S&OP) process to foster integration on its demand chain. Although actors wanted to see what it is to produce, that is to say, the object Production, as a singular object that could be diffused across time and space, Production became more multiple because the S......&OP process itself is a fluid object, but there is still possibility to organise the messy Production. There are connections between the Production multiple and the managerial technology fluid. The fluid enacted the multiplicity of Production thus making it more difficult to be organised because there were...... not judge success or failure of accounting on whether accounting does solve the problem in singular but whether accounting is fluid enough to connect separate multiples....

  12. Connecting Science with Society

    DEFF Research Database (Denmark)

    awareness of the important questions of our society reflected in scientific research and of the answers produced by these research activities. The CRIS2010 conference, entitled “Bringing Science to Society”, therefore seeks to highlight the role of Current Research Information Systems for communicating......CRIS2010, the 10th conference in the bi-annual series organized by euroCRIS, focuses on the connecting role of Current Research Information Systems (CRIS). Aalborg, Denmark where CRIS2010 is held, is located near the intersection of the Northern Sea and Kattegat, a place were not only the waters...... of two seas are exchanged, but also goods and culture. In a similar way, Current Research Information Systems are at the intersection between (publicly funded) research and society. They do not only connect actors, activities and results within the research domain but also play a crucial role in raising...

  13. Connected Cubic Network Graph

    Directory of Open Access Journals (Sweden)

    Burhan Selçuk

    2017-06-01

    Full Text Available Hypercube is a popular interconnection network. Due to the popularity of hypercube, more researchers pay a great effort to develop the different variants of hypercube. In this paper, we have proposed a variant of hypercube which is called as “Connected Cubic Network Graphs”, and have investigated the Hamilton-like properties of Connected Cubic Network Graphs (CCNG. Firstly, we defined CCNG and showed the characteristic analyses of CCNG. Then, we showed that the CCNG has the properties of Hamilton graph, and can be labeled using a Gray coding based recursive algorithm. Finally, we gave the comparison results, a routing algorithm and a bitonic sort algorithm for CCNG. In case of sparsity and cost, CCNG is better than Hypercube.

  14. Transcultural Tectonic Connections

    DEFF Research Database (Denmark)

    Carter, Adrian

    2014-01-01

    This paper presents an understanding of Jørn Utzon, as one of the most profound exponents of a transcultural and tectonic approach to modern architecture in the late twentieth century. The paper will examine the sources of inspiration, intersections and connections in Utzon’s architecture; which...... of cloud formations over a Hawaiian beach, when Utzon was teaching at the University of Hawai’i at Manoa. It is this ability to make connections and translate ideas from one context to another with poetic architectural vision and tectonic integrity, that is at the heart of Utzon’s architecture Together...... with such original unrealised projects as the subterranean Silkeborg Art Museum, Utzon’s work embodies a visionary approach to architecture that is site specific and poetic, tectonic and humane; informed by a profound appreciation of nature and diversity of human cultures, as sources of inspiration and analogy...

  15. MULTIPHASE DROPLET/SLUG BREAK-UP MECHANISM IN MICROFLUIDIC T-JUNCTIONS AT VARIOUS WEBER NUMBERS

    Directory of Open Access Journals (Sweden)

    Wan Leng (Dawn Leow

    2011-10-01

    Full Text Available Normal 0 false false false EN-MY X-NONE X-NONE The formation of immiscible liquid droplets, or slugs, in microchannels features the advantages of volume control and mixing enhancement over single-phase microflows. Although the applications of droplet-based microfluidics have been widely demonstrated, the fundamental physics governing droplet break-up remains an area of active research. This study defines an effective Weber (Weeff number that characterizes the interplay of interfacial tension, shear stress and channel pressure drop in driving slug formation in T-junction microchannel for a relative range of low, intermediate and high flow rates. The immiscible fluid system in this study consists of Tetradecane slug formation in Acetonitrile. The progressive deformation of slug interfaces during break-up events is observed. Experimental results indicate that, at a relatively low Weeff, clean slug break-up occurs at the intersection of the side and main channels. At intermediate Weeff, the connecting neck of the dispersed phase is stretched to a short and thin trail of laminar flow prior to breaking up a short distance downstream of the T-junction. At a relatively high Weeff, the connecting neck develops into a longer and thicker trail of laminar flow that breaks up further downstream of the main channel.

  16. Energy storage connection system

    Science.gov (United States)

    Benedict, Eric L.; Borland, Nicholas P.; Dale, Magdelena; Freeman, Belvin; Kite, Kim A.; Petter, Jeffrey K.; Taylor, Brendan F.

    2012-07-03

    A power system for connecting a variable voltage power source, such as a power controller, with a plurality of energy storage devices, at least two of which have a different initial voltage than the output voltage of the variable voltage power source. The power system includes a controller that increases the output voltage of the variable voltage power source. When such output voltage is substantially equal to the initial voltage of a first one of the energy storage devices, the controller sends a signal that causes a switch to connect the variable voltage power source with the first one of the energy storage devices. The controller then causes the output voltage of the variable voltage power source to continue increasing. When the output voltage is substantially equal to the initial voltage of a second one of the energy storage devices, the controller sends a signal that causes a switch to connect the variable voltage power source with the second one of the energy storage devices.

  17. Loss of adult skeletal muscle stem cells drives age-related neuromuscular junction degeneration.

    Science.gov (United States)

    Liu, Wenxuan; Klose, Alanna; Forman, Sophie; Paris, Nicole D; Wei-LaPierre, Lan; Cortés-Lopéz, Mariela; Tan, Aidi; Flaherty, Morgan; Miura, Pedro; Dirksen, Robert T; Chakkalakal, Joe V

    2017-06-06

    Neuromuscular junction degeneration is a prominent aspect of sarcopenia, the age-associated loss of skeletal muscle integrity. Previously, we showed that muscle stem cells activate and contribute to mouse neuromuscular junction regeneration in response to denervation (Liu et al., 2015). Here, we examined gene expression profiles and neuromuscular junction integrity in aged mouse muscles, and unexpectedly found limited denervation despite a high level of degenerated neuromuscular junctions. Instead, degenerated neuromuscular junctions were associated with reduced contribution from muscle stem cells. Indeed, muscle stem cell depletion was sufficient to induce neuromuscular junction degeneration at a younger age. Conversely, prevention of muscle stem cell and derived myonuclei loss was associated with attenuation of age-related neuromuscular junction degeneration, muscle atrophy, and the promotion of aged muscle force generation. Our observations demonstrate that deficiencies in muscle stem cell fate and post-synaptic myogenesis provide a cellular basis for age-related neuromuscular junction degeneration and associated skeletal muscle decline.

  18. Theory of the Josephson effect in unconventional superconducting junctions with diffusive barriers

    NARCIS (Netherlands)

    Yokoyama, T.; Tanaka, Y.; Golubov, Alexandre Avraamovitch

    2007-01-01

    We study theoretically the Josephson effect in junctions based on unconventional superconductors with diffusive barriers, using the quasiclassical Green's function formalism. Generalized boundary conditions at junction interfaces applicable to unconventional superconductors are derived by

  19. NbN Josephson and Tunnel Junctions for Space THz Observation and Signal Processing

    National Research Council Canada - National Science Library

    Setzu, Romano; Hadacek, Nicolas; Larrey, Vincent; Beaudin, Gerard; Villegier, Jean-Claude

    2005-01-01

    ... (superconductor-normal metal-superconductor) self-shunted junctions are preferred. We present the advantages of the nitride junction technology currently developed at CEA-Grenoble, based on high-performance MTS...

  20. Morphology of electrophysiologically identified junctions between Purkinje fibers and ventricular muscle in rabbit and pig hearts

    NARCIS (Netherlands)

    Tranum-Jensen, J.; Wilde, A. A.; Vermeulen, J. T.; Janse, M. J.

    1991-01-01

    Purkinje fiber-ventricular muscle (PV) junctions were identified by extracellular recording in isolated, superfused preparations from rabbit and pig hearts. Microelectrode recordings from different cell types at the PV junctions were obtained, and the cells recorded from were retrieved