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Sample records for symmetrical cell-cell junctions

  1. The role of Rap1 in cell-cell junction formation

    NARCIS (Netherlands)

    Kooistra, M.R.H.

    2008-01-01

    Both epithelial and endothelial cells form cell-cell junctions at the cell-cell contacts to maintain tissue integrity. Proper regulation of cell-cell junctions is required for the organisation of the tissue and to prevent leakage of blood vessels. In endothelial cells, the cell-cell junctions are

  2. Tuning Collective Cell Migration by Cell-Cell Junction Regulation.

    Science.gov (United States)

    Friedl, Peter; Mayor, Roberto

    2017-04-03

    Collective cell migration critically depends on cell-cell interactions coupled to a dynamic actin cytoskeleton. Important cell-cell adhesion receptor systems implicated in controlling collective movements include cadherins, immunoglobulin superfamily members (L1CAM, NCAM, ALCAM), Ephrin/Eph receptors, Slit/Robo, connexins and integrins, and an adaptive array of intracellular adapter and signaling proteins. Depending on molecular composition and signaling context, cell-cell junctions adapt their shape and stability, and this gradual junction plasticity enables different types of collective cell movements such as epithelial sheet and cluster migration, branching morphogenesis and sprouting, collective network migration, as well as coordinated individual-cell migration and streaming. Thereby, plasticity of cell-cell junction composition and turnover defines the type of collective movements in epithelial, mesenchymal, neuronal, and immune cells, and defines migration coordination, anchorage, and cell dissociation. We here review cell-cell adhesion systems and their functions in different types of collective cell migration as key regulators of collective plasticity. Copyright © 2017 Cold Spring Harbor Laboratory Press; all rights reserved.

  3. Tuning Collective Cell Migration by Cell-Cell Junction Regulation

    NARCIS (Netherlands)

    Friedl, P.; Mayor, R.

    2017-01-01

    Collective cell migration critically depends on cell-cell interactions coupled to a dynamic actin cytoskeleton. Important cell-cell adhesion receptor systems implicated in controlling collective movements include cadherins, immunoglobulin superfamily members (L1CAM, NCAM, ALCAM), Ephrin/Eph

  4. Cell-cell junctions: a target of acoustic overstimulation in the sensory epithelium of the cochlea

    Directory of Open Access Journals (Sweden)

    Zheng Guiliang

    2012-06-01

    Full Text Available Abstract Background Exposure to intense noise causes the excessive movement of the organ of Corti, stretching the organ and compromising sensory cell functions. We recently revealed changes in the transcriptional expression of multiple adhesion-related genes during the acute phases of cochlear damage, suggesting that the disruption of cell-cell junctions is an early event in the process of cochlear pathogenesis. However, the functional state of cell junctions in the sensory epithelium is not clear. Here, we employed graded dextran-FITC, a macromolecule tracer that is impermeable to the organ of Corti under physiological conditions, to evaluate the barrier function of cell junctions in normal and noise-traumatized cochlear sensory epithelia. Results Exposure to an impulse noise of 155 dB (peak sound pressure level caused a site-specific disruption in the intercellular junctions within the sensory epithelium of the chinchilla cochlea. The most vulnerable sites were the junctions among the Hensen cells and between the Hensen and Deiters cells within the outer zone of the sensory epithelium. The junction clefts that formed in the reticular lamina were permeable to 40 and 500 but not 2,000 kDa dextran-FITC macromolecules. Moreover, this study showed that the interruption of junction integrity occurred in the reticular lamina and also in the basilar membrane, a site that had been considered to be resistant to acoustic injury. Finally, our study revealed a general spatial correlation between the site of sensory cell damage and the site of junction disruption. However, the two events lacked a strict one-to-one correlation, suggesting that the disruption of cell-cell junctions is a contributing, but not the sole, factor for initiating acute sensory cell death. Conclusions Impulse noise causes the functional disruption of intercellular junctions in the sensory epithelium of the chinchilla cochlea. This disruption occurs at an early phase of cochlear

  5. A new approach to spherically symmetric junction surfaces and the matching of FLRW regions

    International Nuclear Information System (INIS)

    Kirchner, U

    2004-01-01

    We investigate timelike junctions (with surface layer) between spherically symmetric solutions of the Einstein-field equation. In contrast to previous investigations, this is done in a coordinate system in which the junction surface motion is absorbed in the metric, while all coordinates are continuous at the junction surface. The evolution equations for all relevant quantities are derived. We discuss the no-surface layer case (boundary surface) and study the behaviour for small surface energies. It is shown that one should expect cases in which the speed of light is reached within a finite proper time. We carefully discuss necessary and sufficient conditions for a possible matching of spherically symmetric sections. For timelike junctions between spherically symmetric spacetime sections we show explicitly that the time component of the Lanczos equation always reduces to an identity (independent of the surface equation of state). The results are applied to the matching of Friedmann-LemaItre-Robertson-Walker (FLRW) models. We discuss 'vacuum bubbles' and closed-open junctions in detail. As illustrations several numerical integration results are presented, some of them indicate that (observers comoving with) the junction surface can reach the speed of light within a finite time

  6. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  8. Interaction of c-Src with gap junction protein connexin-43. Role in the regulation of cell-cell communication

    NARCIS (Netherlands)

    Giepmans, B N; Hengeveld, T; Postma, Friso R.; Moolenaar, W H

    2001-01-01

    Cell-cell communication via connexin-43 (Cx43)-based gap junctions is transiently inhibited by certain mitogens, but the underlying regulatory mechanisms are incompletely understood. Our previous studies have implicated the c-Src tyrosine kinase in mediating transient closure of Cx43-based gap

  9. Microfluidic application-specific integrated device for monitoring direct cell-cell communication via gap junctions between individual cell pairs

    Science.gov (United States)

    Lee, Philip J.; Hung, Paul J.; Shaw, Robin; Jan, Lily; Lee, Luke P.

    2005-05-01

    Direct cell-cell communication between adjacent cells is vital for the development and regulation of functional tissues. However, current biological techniques are difficult to scale up for high-throughput screening of cell-cell communication in an array format. In order to provide an effective biophysical tool for the analysis of molecular mechanisms of gap junctions that underlie intercellular communication, we have developed a microfluidic device for selective trapping of cell-pairs and simultaneous optical characterizations. Two different cell populations can be brought into membrane contact using an array of trapping channels with a 2μm by 2μm cross section. Device operation was verified by observation of dye transfer between mouse fibroblasts (NIH3T3) placed in membrane contact. Integration with lab-on-a-chip technologies offers promising applications for cell-based analytical tools such as drug screening, clinical diagnostics, and soft-state biophysical devices for the study of gap junction protein channels in cellular communications. Understanding electrical transport mechanisms via gap junctions in soft membranes will impact quantitative biomedical sciences as well as clinical applications.

  10. NBT-II carcinoma behaviour is not dependent on cell-cell communication through gap junctions.

    Science.gov (United States)

    Lesueur, F; Mesnil, M; Delouvée, A; Girault, J M; Yamasaki, H; Thiery, J P; Jouanneau, J

    2002-05-31

    To study the mechanism(s) underlying the proliferation of heterogeneous cell populations within a solid tumour, the NBT-II rat bladder carcinoma system was used. It has been first investigated whether the different cell populations are coupled through gap junctions (GJIC). Cells overexpressing the Cx43 were generated to test for any tumour suppressive activity in vivo. To determine whether GJIC is essential for tumour proliferation and the establishment of a cooperative community effect, NBT-II cells that are incompetent for cell coupling were generated. The data report that (i) carcinoma cells expressing or not FGF-1 are coupled through GJIC in vitro and in coculture and express the gap junction protein Cx43, (ii) overexpression of Cx43 in these cells does not affect their in vitro coupling capacities and in vivo tumourigenic growth properties, (iii) inhibition of GJIC through antisense strategy has no in vivo obvious consequence on the tumour growth properties of the carcinoma, and (iv) the community effect between two carcinoma cell populations does not critically involve cell coupling through gap junctions.

  11. Signaling by Small GTPases at Cell-Cell junctions: Protein Interactions Building Control and Networks.

    Science.gov (United States)

    Braga, Vania

    2017-09-11

    A number of interesting reports highlight the intricate network of signaling proteins that coordinate formation and maintenance of cell-cell contacts. We have much yet to learn about how the in vitro binding data is translated into protein association inside the cells and whether such interaction modulates the signaling properties of the protein. What emerges from recent studies is the importance to carefully consider small GTPase activation in the context of where its activation occurs, which upstream regulators are involved in the activation/inactivation cycle and the GTPase interacting partners that determine the intracellular niche and extent of signaling. Data discussed here unravel unparalleled cooperation and coordination of functions among GTPases and their regulators in supporting strong adhesion between cells. Copyright © 2017 Cold Spring Harbor Laboratory Press; all rights reserved.

  12. Pseudomonas aeruginosa Transmigrates at Epithelial Cell-Cell Junctions, Exploiting Sites of Cell Division and Senescent Cell Extrusion.

    Directory of Open Access Journals (Sweden)

    Guillaume Golovkine

    2016-01-01

    Full Text Available To achieve systemic infection, bacterial pathogens must overcome the critical and challenging step of transmigration across epithelial barriers. This is particularly true for opportunistic pathogens such as Pseudomonas aeruginosa, an agent which causes nosocomial infections. Despite extensive study, details on the mechanisms used by this bacterium to transmigrate across epithelial tissues, as well as the entry sites it uses, remain speculative. Here, using real-time microscopy and a model epithelial barrier, we show that P. aeruginosa employs a paracellular transmigration route, taking advantage of altered cell-cell junctions at sites of cell division or when senescent cells are expelled from the cell layer. Once a bacterium transmigrates, it is followed by a cohort of bacteria using the same entry point. The basal compartment is then invaded radially from the initial penetration site. Effective transmigration and propagation require type 4 pili, the type 3 secretion system (T3SS and a flagellum, although flagellum-deficient bacteria can occasionally invade the basal compartment from wounded areas. In the basal compartment, the bacteria inject the T3SS toxins into host cells, disrupting the cytoskeleton and focal contacts to allow their progression under the cells. Thus, P. aeruginosa exploits intrinsic host cell processes to breach the epithelium and invade the subcellular compartment.

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

    Directory of Open Access Journals (Sweden)

    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.

  14. Even parity junction conditions for perturbations on most general spherically symmetric space--time

    International Nuclear Information System (INIS)

    Gerlach, U.H.; Sengupta, U.K.

    1979-01-01

    A new highly efficient and versatile general relativistic perturbational formalism for general matter occupied spherically symmetric space--times is developed. The perturbations are geometrical objects on the two dimensional totally geodesic submanifold spanned by the radial and time coordinates. The geometrical objects are ''gauge invariant'' scalars, vectors, and tensors which are independent of infinitesimal coordinate transformations on the background space--time. This article gives the even parity gauge invariant perturbation objects for arbitrary background scalars, vectors, and symmetric tensors on a spherically symmetric space--time. In particular, metric, matter, first and second fundamental forms, as well as vacuum-matter interface gauge invariant perturbations for a collapsing star are given. In addition four even parity continuity conditions across discontinuous timelike hypersurfaces are given. Two are conditions on the metric gauge invariants, one is a condition on the perturbation away from the spherical contour of the interface, and the fourth couples that contour perturbation to the metric gauge invariants

  15. Minimum Junction Temperature Swing for DFIG to Ride Through Symmetrical Voltage Dips

    DEFF Research Database (Denmark)

    Zhou, Dao; Blaabjerg, Frede

    2015-01-01

    Doubly-Fed Induction Generator (DFIG) system is popular for wind turbines above 1 MW. Existing issues for a DFIG system to ride through a symmetrical grid fault are addressed in terms of the internal and external challenges. Based on the conventional demagnetizing current control, the design...

  16. Intravital FRAP Imaging using an E-cadherin-GFP Mouse Reveals Disease- and Drug-Dependent Dynamic Regulation of Cell-Cell Junctions in Live Tissue

    Directory of Open Access Journals (Sweden)

    Zahra Erami

    2016-01-01

    Full Text Available E-cadherin-mediated cell-cell junctions play a prominent role in maintaining the epithelial architecture. The disruption or deregulation of these adhesions in cancer can lead to the collapse of tumor epithelia that precedes invasion and subsequent metastasis. Here we generated an E-cadherin-GFP mouse that enables intravital photobleaching and quantification of E-cadherin mobility in live tissue without affecting normal biology. We demonstrate the broad applications of this mouse by examining E-cadherin regulation in multiple tissues, including mammary, brain, liver, and kidney tissue, while specifically monitoring E-cadherin mobility during disease progression in the pancreas. We assess E-cadherin stability in native pancreatic tissue upon genetic manipulation involving Kras and p53 or in response to anti-invasive drug treatment and gain insights into the dynamic remodeling of E-cadherin during in situ cancer progression. FRAP in the E-cadherin-GFP mouse, therefore, promises to be a valuable tool to fundamentally expand our understanding of E-cadherin-mediated events in native microenvironments.

  17. Restoration of E-cadherin Cell-Cell Junctions Requires Both Expression of E-cadherin and Suppression of ERK MAP Kinase Activation in Ras-Transformed Breast Epithelial Cells

    Directory of Open Access Journals (Sweden)

    Quanwen Li

    2008-12-01

    Full Text Available E-cadherin is a main component of the cell-cell adhesion junctions that play a principal role in maintaining normal breast epithelial cell morphology. Breast and other cancers that have up-regulated activity of Ras are often found to have down-regulated or mislocalized E-cadherin expression. Disruption of E-cadherin junctions and consequent gain of cell motility contribute to the process known as epithelial-to-mesenchymal transition (EMT. Enforced expression of E-cadherin or inhibition of Ras-signal transduction pathway has been shown to be effective in causing reversion of EMT in several oncogene-transformed and cancer-derived cell lines. In this study, we investigated MCF10A human breast epithelial cells and derivatives that were transformed with either activated H-Ras or N-Ras to test for the reversion of EMT by inhibition of Ras-driven signaling pathways. Our results demonstrated that inhibition of mitogen-activated protein kinase (MAPK kinase, but not PI3-kinase, Rac, or myosin light chain kinase, was able to completely restore E-cadherin cell-cell junctions and epithelial morphology in cell lines with moderate H-Ras expression. In MCF10A cells transformed by a high-level expression of activated H-Ras or N-Ras, restoration of E-cadherin junction required both the enforced reexpression of E-cadherin and suppression of MAPK kinase. Enforced expression of E-cadherin alone did not induce reversion from the mesenchymal phenotype. Our results suggest that Ras transformation has at least two independent actions to disrupt E-cadherin junctions, with effects to cause both mislocalization of E-cadherin away from the cell surface and profound decrease in the expression of E-cadherin.

  18. 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.

  19. Tropomyosin-1 protects transformed alveolar epithelial cells against cigaret smoke extract through the stabilization of F-actin-dependent cell-cell junctions.

    Science.gov (United States)

    Gagat, Maciej; Grzanka, Dariusz; Izdebska, Magdalena; Sroka, Wiktor Dariusz; Hałas-Wiśniewska, Marta; Grzanka, Alina

    2016-04-01

    The aim of the study was to estimate the effect of tropomyosin-1-based structural stabilization of F-actin in transformed human alveolar epithelial line H1299 cells subjected to high oxidative stress induced by cigaret smoke extract. We demonstrated here that cigaret smoke extract induces cell shrinking and detachment as a consequence of F-actin cytoskeleton degradation in H1299 cells not overexpressing tropomyosin-1. Furthermore, the treatment of these cells with cigaret smoke extract resulted in the loss of peripheral localization of ZO-1 and initiated apoptosis. In contrast, structural stabilization of F-actin, by overexpression of tropomyosin-1, preserved cell to cell interactions through the attenuation of cortical actin organization into thin fibers and thus protected these cells against oxidative stress-induced degradation of actin cytoskeleton and cell death. In conclusion, we suggest that structural stabilization of thin cortical F-actin fibers increases link between tight junctions proteins and actin cytoskeleton and thus protects H1299 cells against cigaret smoke extract. Copyright © 2016 Elsevier GmbH. All rights reserved.

  20. Symmetric and Asymmetric Magnetic Tunnel Junctions with Embedded Nanoparticles: Effects of Size Distribution and Temperature on Tunneling Magnetoresistance and Spin Transfer Torque.

    Science.gov (United States)

    Useinov, Arthur; Lin, Hsiu-Hau; Lai, Chih-Huang

    2017-08-21

    The problem of the ballistic electron tunneling is considered in magnetic tunnel junction with embedded non-magnetic nanoparticles (NP-MTJ), which creates additional conducting middle layer. The strong temperature impact was found in the system with averaged NP diameter d av  tunneling magnetoresistance (TMR) voltage behaviors. The low temperature approach also predicts step-like TMR and quantized in-plane spin transfer torque (STT) effects. The robust asymmetric STT respond is found due to voltage sign inversion in NP-MTJs with barrier asymmetry. Furthermore, it is shown how size distribution of NPs as well as quantization rules modify the spin-current filtering properties of the nanoparticles in ballistic regime. Different quantization rules for the transverse component of the wave vector are considered to overpass the dimensional threshold (d av  ≈ 1.8 nm) between quantum well and bulk-assisted states of the middle layer.

  1. Symmetric textures

    International Nuclear Information System (INIS)

    Ramond, P.

    1993-01-01

    The Wolfenstein parametrization is extended to the quark masses in the deep ultraviolet, and an algorithm to derive symmetric textures which are compatible with existing data is developed. It is found that there are only five such textures

  2. 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.

  3. 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

  4. 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

  5. Symmetrization of Facade Layouts

    KAUST Repository

    Jiang, Haiyong

    2016-02-26

    We present an automatic approach for symmetrizing urban facade layouts. Our method can generate a symmetric layout through minimally modifying the original input layout. Based on the principles of symmetry in urban design, we formulate facade layout symmetrization as an optimization problem. Our method further enhances the regularity of the final layout by redistributing and aligning elements in the layout. We demonstrate that the proposed solution can effectively generate symmetric facade layouts.

  6. Facade Layout Symmetrization

    KAUST Repository

    Jiang, Haiyong

    2016-04-11

    We present an automatic algorithm for symmetrizing facade layouts. Our method symmetrizes a given facade layout while minimally modifying the original layout. Based on the principles of symmetry in urban design, we formulate the problem of facade layout symmetrization as an optimization problem. Our system further enhances the regularity of the final layout by redistributing and aligning boxes in the layout. We demonstrate that the proposed solution can generate symmetric facade layouts efficiently. © 2015 IEEE.

  7. 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....

  8. 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...

  9. 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.

  10. On Symmetric Polynomials

    OpenAIRE

    Golden, Ryan; Cho, Ilwoo

    2015-01-01

    In this paper, we study structure theorems of algebras of symmetric functions. Based on a certain relation on elementary symmetric polynomials generating such algebras, we consider perturbation in the algebras. In particular, we understand generators of the algebras as perturbations. From such perturbations, define injective maps on generators, which induce algebra-monomorphisms (or embeddings) on the algebras. They provide inductive structure theorems on algebras of symmetric polynomials. As...

  11. Quantum Bounded Symmetric Domains

    OpenAIRE

    Vaksman, L. L.

    2008-01-01

    This is Leonid Vaksman's monograph "Quantum bounded symmetric domains" (in Russian), preceded with an English translation of the table of contents and (a part) of the introduction. Quantum bounded symmetric domains are interesting from several points of view. In particular, they provide interesting examples for noncommutative complex analysis (i.e., the theory of subalgebras of C^*-algebars) initiated by W. Arveson.

  12. Symmetric cryptographic protocols

    CERN Document Server

    Ramkumar, Mahalingam

    2014-01-01

    This book focuses on protocols and constructions that make good use of symmetric pseudo random functions (PRF) like block ciphers and hash functions - the building blocks for symmetric cryptography. Readers will benefit from detailed discussion of several strategies for utilizing symmetric PRFs. Coverage includes various key distribution strategies for unicast, broadcast and multicast security, and strategies for constructing efficient digests of dynamic databases using binary hash trees.   •        Provides detailed coverage of symmetric key protocols •        Describes various applications of symmetric building blocks •        Includes strategies for constructing compact and efficient digests of dynamic databases

  13. A symmetrical rail accelerator

    International Nuclear Information System (INIS)

    Igenbergs, E.

    1991-01-01

    This paper reports on the symmetrical rail accelerator that has four rails, which are arranged symmetrically around the bore. The opposite rails have the same polarity and the adjacent rails the opposite polarity. In this configuration the radial force acting upon the individual rails is significantly smaller than in a conventional 2-rail configuration and a plasma armature is focussed towards the axis of the barrel. Experimental results indicate a higher efficiency compared to a conventional rail accelerator

  14. Symmetric eikonal expansion

    International Nuclear Information System (INIS)

    Matsuki, Takayuki

    1976-01-01

    Symmetric eikonal expansion for the scattering amplitude is formulated for nonrelativistic and relativistic potential scatterings and also for the quantum field theory. The first approximations coincide with those of Levy and Sucher. The obtained scattering amplitudes are time reversal invariant for all cases and are crossing symmetric for the quantum field theory in each order of approximation. The improved eikonal phase introduced by Levy and Sucher is also derived from the different approximation scheme from the above. (auth.)

  15. Symmetric Tensor Decomposition

    DEFF Research Database (Denmark)

    Brachat, Jerome; Comon, Pierre; Mourrain, Bernard

    2010-01-01

    We present an algorithm for decomposing a symmetric tensor, of dimension n and order d, as a sum of rank-1 symmetric tensors, extending the algorithm of Sylvester devised in 1886 for binary forms. We recall the correspondence between the decomposition of a homogeneous polynomial in n variables...... of polynomial equations of small degree in non-generic cases. We propose a new algorithm for symmetric tensor decomposition, based on this characterization and on linear algebra computations with Hankel matrices. The impact of this contribution is two-fold. First it permits an efficient computation...... of the decomposition of any tensor of sub-generic rank, as opposed to widely used iterative algorithms with unproved global convergence (e.g. Alternate Least Squares or gradient descents). Second, it gives tools for understanding uniqueness conditions and for detecting the rank....

  16. Multiparty symmetric sum types

    DEFF Research Database (Denmark)

    Nielsen, Lasse; Yoshida, Nobuko; Honda, Kohei

    2010-01-01

    This paper introduces a new theory of multiparty session types based on symmetric sum types, by which we can type non-deterministic orchestration choice behaviours. While the original branching type in session types can represent a choice made by a single participant and accepted by others...... determining how the session proceeds, the symmetric sum type represents a choice made by agreement among all the participants of a session. Such behaviour can be found in many practical systems, including collaborative workflow in healthcare systems for clinical practice guidelines (CPGs). Processes...... with the symmetric sums can be embedded into the original branching types using conductor processes. We show that this type-driven embedding preserves typability, satisfies semantic soundness and completeness, and meets the encodability criteria adapted to the typed setting. The theory leads to an efficient...

  17. PT-symmetric strings

    International Nuclear Information System (INIS)

    Amore, Paolo; Fernández, Francisco M.; Garcia, Javier; Gutierrez, German

    2014-01-01

    We study both analytically and numerically the spectrum of inhomogeneous strings with PT-symmetric density. We discuss an exactly solvable model of PT-symmetric string which is isospectral to the uniform string; for more general strings, we calculate exactly the sum rules Z(p)≡∑ n=1 ∞ 1/E n p , with p=1,2,… and find explicit expressions which can be used to obtain bounds on the lowest eigenvalue. A detailed numerical calculation is carried out for two non-solvable models depending on a parameter, obtaining precise estimates of the critical values where pair of real eigenvalues become complex. -- Highlights: •PT-symmetric Hamiltonians exhibit real eigenvalues when PT symmetry is unbroken. •We study PT-symmetric strings with complex density. •They exhibit regions of unbroken PT symmetry. •We calculate the critical parameters at the boundaries of those regions. •There are exact real sum rules for some particular complex densities

  18. Homogenous finitary symmetric groups

    Directory of Open Access Journals (Sweden)

    Otto‎. ‎H‎. Kegel

    2015-03-01

    Full Text Available We characterize strictly diagonal type of embeddings of finitary symmetric groups in terms of cardinality and the characteristic. Namely, we prove the following. Let kappa be an infinite cardinal. If G=underseti=1stackrelinftybigcupG i , where G i =FSym(kappan i , (H=underseti=1stackrelinftybigcupH i , where H i =Alt(kappan i , is a group of strictly diagonal type and xi=(p 1 ,p 2 ,ldots is an infinite sequence of primes, then G is isomorphic to the homogenous finitary symmetric group FSym(kappa(xi (H is isomorphic to the homogenous alternating group Alt(kappa(xi , where n 0 =1,n i =p 1 p 2 ldotsp i .

  19. Symmetric waterbomb origami.

    Science.gov (United States)

    Chen, Yan; Feng, Huijuan; Ma, Jiayao; Peng, Rui; You, Zhong

    2016-06-01

    The traditional waterbomb origami, produced from a pattern consisting of a series of vertices where six creases meet, is one of the most widely used origami patterns. From a rigid origami viewpoint, it generally has multiple degrees of freedom, but when the pattern is folded symmetrically, the mobility reduces to one. This paper presents a thorough kinematic investigation on symmetric folding of the waterbomb pattern. It has been found that the pattern can have two folding paths under certain circumstance. Moreover, the pattern can be used to fold thick panels. Not only do the additional constraints imposed to fold the thick panels lead to single degree of freedom folding, but the folding process is also kinematically equivalent to the origami of zero-thickness sheets. The findings pave the way for the pattern being readily used to fold deployable structures ranging from flat roofs to large solar panels.

  20. Symmetric vectors and algebraic classification

    International Nuclear Information System (INIS)

    Leibowitz, E.

    1980-01-01

    The concept of symmetric vector field in Riemannian manifolds, which arises in the study of relativistic cosmological models, is analyzed. Symmetric vectors are tied up with the algebraic properties of the manifold curvature. A procedure for generating a congruence of symmetric fields out of a given pair is outlined. The case of a three-dimensional manifold of constant curvature (''isotropic universe'') is studied in detail, with all its symmetric vector fields being explicitly constructed

  1. Representations of locally symmetric spaces

    International Nuclear Information System (INIS)

    Rahman, M.S.

    1995-09-01

    Locally symmetric spaces in reference to globally and Hermitian symmetric Riemannian spaces are studied. Some relations between locally and globally symmetric spaces are exhibited. A lucid account of results on relevant spaces, motivated by fundamental problems, are formulated as theorems and propositions. (author). 10 refs

  2. The gap junction protein connexin43 interacts with the second PDZ domain of the zona occludens-1 protein

    NARCIS (Netherlands)

    Giepmans, B N; Moolenaar, W H

    1998-01-01

    Gap junctions mediate cell-cell communication in almost all tissues and are composed of channel-forming integral membrane proteins, termed connexins [1-3]. Connexin43 (Cx43) is the most widely expressed and the most well-studied member of this family. Cx43-based cell-cell communication is regulated

  3. Cell-extracellular matrix and cell-cell adhesion are linked by syndecan-4

    DEFF Research Database (Denmark)

    Pakideeri Karat, Sandeep Gopal; Multhaupt, Hinke A B; Pocock, Roger

    2017-01-01

    Cell-extracellular matrix (ECM) and cell-cell junctions that employ microfilaments are sites of tension. They are important for tissue repair, morphogenetic movements and can be emblematic of matrix contraction in fibrotic disease and the stroma of solid tumors. One cell surface receptor, syndecan......-4, has been shown to regulate focal adhesions, junctions that form at the ends of microfilament bundles in response to matrix components such as fibronectin. Recently it has been shown that signaling emanating from this proteoglycan receptor includes regulation of Rho family GTPases and cytosolic...

  4. 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.)

  5. 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.

  6. 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

  7. 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

  8. Rac1 acts in conjunction with Nedd4 and dishevelled-1 to promote maturation of cell-cell contacts

    NARCIS (Netherlands)

    M. Nethe (Micha); B.J. de Kreuk (Bart-Jan); D.V.F. Tauriello (Daniele); E.C. Anthony (Eloise); B. Snoek (Barbara); T. Stumpel (Thomas); M. Salinas; K. Maurice (Karelle); D. Geerts (Dirk); A.M. Deelder (André); P. Hensbergen (Paul); P.L. Hordijk (Peter )

    2012-01-01

    textabstractThe Rho-GTPase Rac1 promotes actin polymerization and membrane protrusion that mediate initial contact and subsequent maturation of cell-cell junctions. Here we report that Rac1 associates with the ubiquitin-protein ligase neural precursor cell expressed developmentally down-regulated 4

  9. Symmetric instability of monsoon flows

    OpenAIRE

    Krishnakumar, V.; Lau, K.-M.

    2011-01-01

    Using a zonally symmetric multi-level moist linear model, we have examined the possibility of symmetric instability in the monsoon region. Stability analyses with a zonally symmetric model using monthly ECMWF (Jan – Dec) zonal basic flows revealed both unstable as well as neutral modes. In the absence of cumulus heating, the linear stability of the monsoon flow changes dramatically with the emergence of many unstable modes in the month of May and lasting through August; whereas with the inclu...

  10. Symmetric q-Bessel functions

    Directory of Open Access Journals (Sweden)

    Giuseppe Dattoli

    1996-05-01

    Full Text Available q analog of bessel functions, symmetric under the interchange of q and q^ −1 are introduced. The definition is based on the generating function realized as product of symmetric q-exponential functions with appropriate arguments. Symmetric q-Bessel function are shown to satisfy various identities as well as second-order q-differential equations, which in the limit q → 1 reproduce those obeyed by the usual cylindrical Bessel functions. A brief discussion on the possible algebraic setting for symmetric q-Bessel functions is also provided.

  11. Chlorpromazine reduces the intercellular communication via gap junctions in mammalian cells

    International Nuclear Information System (INIS)

    Orellana, Juan A.; Palacios-Prado, Nicolas; Saez, Juan C.

    2006-01-01

    In the work presented herein, we evaluated the effect of chlorpromazine (CPZ) on gap junctions expressed by two mammalian cell types; Gn-11 cells (cell line derived from mouse LHRH neurons) and rat cortical astrocytes maintained in culture. We also attempted to elucidate possible mechanisms of action of CPZ effects on gap junctions. CPZ, in concentrations comparable with doses used to treat human diseases, was found to reduce the intercellular communication via gap junctions as evaluated with measurements of dye coupling (Lucifer yellow). In both cell types, maximal inhibition of functional gap junctions was reached within about 1 h of treatment with CPZ, an recovery was almost complete at about 5 h after CPZ wash out. In both cell types, CPZ treatment increased the phosphorylation state of connexin43 (Cx43), a gap junction protein subunit. Moreover, CPZ reduced the reactivity of Cx43 (immunofluorescence) at cell interfaces and concomitantly increased its reactivity in intracellular vesicles, suggesting an increased retrieval from and/or reduced insertion into the plasma membrane. CPZ also caused cellular retraction reducing cell-cell contacts in a reversible manner. The reduction in contact area might destabilize existing gap junctions and abrogate formation of new ones. Moreover, the CPZ-induced reduction in gap junctional communication may depend on the connexins (Cxs) forming the junctions. If Cx43 were the only connexin expressed, MAPK-dependent phosphorylation of this connexin would induce closure of gap junction channels

  12. 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...

  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...... 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...

  14. Symmetric Decomposition of Asymmetric Games.

    Science.gov (United States)

    Tuyls, Karl; Pérolat, Julien; Lanctot, Marc; Ostrovski, Georg; Savani, Rahul; Leibo, Joel Z; Ord, Toby; Graepel, Thore; Legg, Shane

    2018-01-17

    We introduce new theoretical insights into two-population asymmetric games allowing for an elegant symmetric decomposition into two single population symmetric games. Specifically, we show how an asymmetric bimatrix game (A,B) can be decomposed into its symmetric counterparts by envisioning and investigating the payoff tables (A and B) that constitute the asymmetric game, as two independent, single population, symmetric games. We reveal several surprising formal relationships between an asymmetric two-population game and its symmetric single population counterparts, which facilitate a convenient analysis of the original asymmetric game due to the dimensionality reduction of the decomposition. The main finding reveals that if (x,y) is a Nash equilibrium of an asymmetric game (A,B), this implies that y is a Nash equilibrium of the symmetric counterpart game determined by payoff table A, and x is a Nash equilibrium of the symmetric counterpart game determined by payoff table B. Also the reverse holds and combinations of Nash equilibria of the counterpart games form Nash equilibria of the asymmetric game. We illustrate how these formal relationships aid in identifying and analysing the Nash structure of asymmetric games, by examining the evolutionary dynamics of the simpler counterpart games in several canonical examples.

  15. Symmetric $q$-deformed KP hierarch

    OpenAIRE

    Tian, Kelei; He, Jingsong; Su, Yucai

    2014-01-01

    Based on the analytic property of the symmetric $q$-exponent $e_q(x)$, a new symmetric $q$-deformed Kadomtsev-Petviashvili ($q$-KP) hierarchy associated with the symmetric $q$-derivative operator $\\partial_q$ is constructed. Furthermore, the symmetric $q$-CKP hierarchy and symmetric $q$-BKP hierarchy are defined. Here we also investigate the additional symmetries of the symmetric $q$-KP hierarchy.

  16. Determination of apical membrane polarity in mammary epithelial cell cultures: The role of cell-cell, cell-substratum, and membrane-cytoskeleton interactions

    Energy Technology Data Exchange (ETDEWEB)

    Parry, G.; Beck, J.C.; Moss, L.; Bartley, J. (Lawrence Berkeley Lab., CA (United States)); Ojakian, G.K. (State Univ. of New York, Brooklyn (United States))

    1990-06-01

    The membrane glycoprotein, PAS-O, is a major differentiation antigen on mammary epithelial cells and is located exclusively in the apical domain of the plasma membrane. The authors have used 734B cultured human mammary carcinoma cells as a model system to study the role of tight junctions, cell-substratum contacts, and submembranous cytoskeletal elements in restricting PAS-O to the apical membrane. Immunofluorescence and immunoelectronmicroscopy experiments demonstrated that while tight junctions demarcate PAS-O distribution in confluent cultures, apical polarity could be established at low culture densities when cells could not form tight junctions with neighboring cells. They suggest, then, that interactions between vitronectin and its receptor, are responsible for establishment of membrane domains in the absence of tight junctions. The role of cytoskeletal elements in restricting PAS-O distribution was examined by treating cultures with cytochalasin D, colchicine, or acrylamide. Cytochalasin D led to a redistribution of PAS0O while colchicine and acrylamide did not. They hypothesize that PAS-O is restricted to the apical membrane by interactions with a microfilament network and that the cytoskeletal organization is dependent upon cell-cell and cell-substratum interactions.

  17. The role of the beta1 subunit of the Na,K-ATPase and its glycosylation in cell-cell adhesion.

    Science.gov (United States)

    Vagin, Olga; Tokhtaeva, Elmira; Sachs, George

    2006-12-22

    Based on recent data showing that overexpression of the Na,K-ATPase beta(1) subunit increased cell-cell adhesion of nonpolarized cells, we hypothesized that the beta(1) subunit can also be involved in the formation of cell-cell contacts in highly polarized epithelial cells. In support of this hypothesis, in Madin-Darby canine kidney (MDCK) cells, the Na,K-ATPase alpha(1) and beta(1) subunits were detected as precisely co-localized with adherens junctions in all stages of the monolayer formation starting from the initiation of cell-cell contact. The Na,K-ATPase and adherens junction protein, beta-catenin, stayed partially co-localized even after their internalization upon disruption of intercellular contacts by Ca(2+) depletion of the medium. The Na,K-ATPase subunits remained co-localized with the adherens junctions after detergent treatment of the cells. In contrast, the heterodimer formed by expressed unglycosylated Na,K-ATPase beta(1) subunit and the endogenous alpha(1) subunit was easily dissociated from the adherens junctions and cytoskeleton by the detergent extraction. The MDCK cell line in which half of the endogenous beta(1) subunits in the lateral membrane were substituted by unglycosylated beta(1) subunits displayed a decreased ability to form cell-to-cell contacts. Incubation of surface-attached MDCK cells with an antibody against the extracellular domain of the Na,K-ATPase beta(1) subunit specifically inhibited cell-cell contact formation. We conclude that the Na,K-ATPase beta(1) subunit is involved in the process of intercellular adhesion and is necessary for association of the heterodimeric Na,K-ATPase with the adherens junctions. Further, normal glycosylation of the Na,K-ATPase beta(1) subunit is essential for the stable association of the pump with the adherens junctions and plays an important role in cell-cell contact formation.

  18. 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.

  19. TNF-alpha induced junctional modulation enhances response to radiation in Caco-2 cells

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Yeonjoo; Ahn, Hyein; Park, Jina; Lee, Byungryong; Chung, Eunkyung [Hallym University, Seoul (Korea, Republic of); Yi, Jaeoun [KIRAMS, Seoul (Korea, Republic of)

    2007-10-15

    The Adhesion molecules mediated cell-cell and cell matrix interactions are essential for variety of physiological and pathological processes including maintenance of normal tissues integrity as well as tumor development and progression. Cell-cell interaction is initiated by interactions of tight junctional proteins with neighboring cells. Tight junctions govern the paracellular permeability of endothelial and epithelial cells. Aberrations of tight junction formation are an early and key event during vascular spread cancer and inflammation. TNF-alpha plays an important role in the intestinal inflammation by increase of intestinal epithelial tight junction permeability. It has been reported that TNF alpha- modulated intestinal epithelial tight junction barrier is mediated by myosin light-chain kinase protein expression through NFk-B activation. However, the alterations of tight junctional proteins involved in the TNF-alpha-induced increase of intestinal TJ permeability remain unclear. Claudin is essential to the formation and maintenance of tight junction (TJ) and has been identified 24 members so far. Claudin-1, 3, 4, 6, 10 and 16 have been shown altered in various cancers and they may have important roles in cell survival, motility, and invasion of cancer cells. However, the functions of these proteins in tumorigenesis and inflammation are still being elucidated.

  20. Differential geometry and symmetric spaces

    CERN Document Server

    Helgason, Sigurdur

    2001-01-01

    Sigurdur Helgason's Differential Geometry and Symmetric Spaces was quickly recognized as a remarkable and important book. For many years, it was the standard text both for Riemannian geometry and for the analysis and geometry of symmetric spaces. Several generations of mathematicians relied on it for its clarity and careful attention to detail. Although much has happened in the field since the publication of this book, as demonstrated by Helgason's own three-volume expansion of the original work, this single volume is still an excellent overview of the subjects. For instance, even though there

  1. Looking for symmetric Bell inequalities

    International Nuclear Information System (INIS)

    Bancal, Jean-Daniel; Gisin, Nicolas; Pironio, Stefano

    2010-01-01

    Finding all Bell inequalities for a given number of parties, measurement settings and measurement outcomes is in general a computationally hard task. We show that all Bell inequalities which are symmetric under the exchange of parties can be found by examining a symmetrized polytope which is simpler than the full Bell polytope. As an illustration of our method, we generate 238 885 new Bell inequalities and 1085 new Svetlichny inequalities. We find, in particular, facet inequalities for Bell experiments involving two parties and two measurement settings that are not of the Collins-Gisin-Linden-Massar-Popescu type.

  2. Symmetric autocompensating quantum key distribution

    Science.gov (United States)

    Walton, Zachary D.; Sergienko, Alexander V.; Levitin, Lev B.; Saleh, Bahaa E. A.; Teich, Malvin C.

    2004-08-01

    We present quantum key distribution schemes which are autocompensating (require no alignment) and symmetric (Alice and Bob receive photons from a central source) for both polarization and time-bin qubits. The primary benefit of the symmetric configuration is that both Alice and Bob may have passive setups (neither Alice nor Bob is required to make active changes for each run of the protocol). We show that both the polarization and the time-bin schemes may be implemented with existing technology. The new schemes are related to previously described schemes by the concept of advanced waves.

  3. The hallmarks of cell-cell fusion.

    Science.gov (United States)

    Hernández, Javier M; Podbilewicz, Benjamin

    2017-12-15

    Cell-cell fusion is essential for fertilization and organ development. Dedicated proteins known as fusogens are responsible for mediating membrane fusion. However, until recently, these proteins either remained unidentified or were poorly understood at the mechanistic level. Here, we review how fusogens surmount multiple energy barriers to mediate cell-cell fusion. We describe how early preparatory steps bring membranes to a distance of ∼10 nm, while fusogens act in the final approach between membranes. The mechanical force exerted by cell fusogens and the accompanying lipidic rearrangements constitute the hallmarks of cell-cell fusion. Finally, we discuss the relationship between viral and eukaryotic fusogens, highlight a classification scheme regrouping a superfamily of fusogens called Fusexins, and propose new questions and avenues of enquiry. © 2017. Published by The Company of Biologists Ltd.

  4. Symmetric Key Authentication Services Revisited

    NARCIS (Netherlands)

    Crispo, B.; Popescu, B.C.; Tanenbaum, A.S.

    2004-01-01

    Most of the symmetric key authentication schemes deployed today are based on principles introduced by Needham and Schroeder [15] more than twenty years ago. However, since then, the computing environment has evolved from a LAN-based client-server world to include new paradigms, including wide area

  5. A charged spherically symmetric solution

    Indian Academy of Sciences (India)

    A charged spherically symmetric solution. K MOODLEY, S D MAHARAJ and K S GOVINDER. School of Mathematical and Statistical Sciences, University of Natal, Durban 4041, South Africa. Email: maharaj@nu.ac.za. MS received 8 April 2002; revised 7 April 2003; accepted 23 June 2003. Abstract. We find a solution of the ...

  6. The symmetric longest queue system

    NARCIS (Netherlands)

    van Houtum, Geert-Jan; Adan, Ivo; van der Wal, Jan

    1997-01-01

    We derive the performance of the exponential symmetric longest queue system from two variants: a longest queue system with Threshold Rejection of jobs and one with Threshold Addition of jobs. It is shown that these two systems provide lower and upper bounds for the performance of the longest queue

  7. Symmetric group representations and Z

    OpenAIRE

    Adve, Anshul; Yong, Alexander

    2017-01-01

    We discuss implications of the following statement about the representation theory of symmetric groups: every integer appears infinitely often as an irreducible character evaluation, and every nonnegative integer appears infinitely often as a Littlewood-Richardson coefficient and as a Kronecker coefficient.

  8. A characterization of symmetric domains

    Czech Academy of Sciences Publication Activity Database

    Engliš, Miroslav

    2006-01-01

    Roč. 46, č. 1 (2006), s. 123-146 ISSN 0023-608X R&D Projects: GA AV ČR(CZ) IAA1019304 Institutional research plan: CEZ:AV0Z10190503 Keywords : Kaehler manifold * symmetric space * Berezin transform Subject RIV: BA - General Mathematics Impact factor: 0.270, year: 2006

  9. Vassiliev Invariants from Symmetric Spaces

    DEFF Research Database (Denmark)

    Biswas, Indranil; Gammelgaard, Niels Leth

    We construct a natural framed weight system on chord diagrams from the curvature tensor of any pseudo-Riemannian symmetric space. These weight systems are of Lie algebra type and realized by the action of the holonomy Lie algebra on a tangent space. Among the Lie algebra weight systems, they are ...

  10. Cdc42 is crucial for the maturation of primordial cell junctions in keratinocytes independent of Rac1

    DEFF Research Database (Denmark)

    Du, Dan; Pedersen, Esben; Wang, Zhipeng

    2008-01-01

    Cell-cell contacts are crucial for the integrity of all tissues. Contrasting reports have been published about the role of Cdc42 in epithelial cell-cell contacts in vitro. In keratinocytes, it was suggested that Rac1 and not Cdc42 is crucial for the formation of mature epithelial junctions, based....... Inhibition of aPKCzeta by the inhibitor Gö6983 reproduced the phenotype, suggesting that decreased activation of aPKCzeta was sufficient to explain the defective junctional maturation. In the absence of Cdc42, Rac1 activation was strongly decreased, indicating that Cdc42 is upstream of Rac1 activation...

  11. 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

  12. Symmetric imaging findings in neuroradiology

    International Nuclear Information System (INIS)

    Zlatareva, D.

    2015-01-01

    Full text: Learning objectives: to make a list of diseases and syndromes which manifest as bilateral symmetric findings on computed tomography and magnetic resonance imaging; to discuss the clinical and radiological differential diagnosis for these diseases; to explain which of these conditions necessitates urgent therapy and when additional studies and laboratory can precise diagnosis. There is symmetry in human body and quite often we compare the affected side to the normal one but in neuroradiology we might have bilateral findings which affected pair structures or corresponding anatomic areas. It is very rare when clinical data prompt diagnosis. Usually clinicians suspect such an involvement but Ct and MRI can reveal symmetric changes and are one of the leading diagnostic tool. The most common location of bilateral findings is basal ganglia and thalamus. There are a number of diseases affecting these structures symmetrically: metabolic and systemic diseases, intoxication, neurodegeneration and vascular conditions, toxoplasmosis, tumors and some infections. Malformations of cortical development and especially bilateral perisylvian polymicrogyria requires not only exact report on the most affected parts but in some cases genetic tests or combination with other clinical symptoms. In the case of herpes simplex encephalitis bilateral temporal involvement is common and this finding very often prompt therapy even before laboratory results. Posterior reversible encephalopathy syndrome (PReS) and some forms of hypoxic ischemic encephalopathy can lead to symmetric changes. In these acute conditions MR plays a crucial role not only in diagnosis but also in monitoring of the therapeutic effect. Patients with neurofibromatosis type 1 or type 2 can demonstrate bilateral optic glioma combined with spinal neurofibroma and bilateral acoustic schwanoma respectively. Mirror-image aneurysm affecting both internal carotid or middle cerebral arteries is an example of symmetry in

  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. Understanding symmetrical components for power system modeling

    CERN Document Server

    Das, J C

    2017-01-01

    This book utilizes symmetrical components for analyzing unbalanced three-phase electrical systems, by applying single-phase analysis tools. The author covers two approaches for studying symmetrical components; the physical approach, avoiding many mathematical matrix algebra equations, and a mathematical approach, using matrix theory. Divided into seven sections, topics include: symmetrical components using matrix methods, fundamental concepts of symmetrical components, symmetrical components –transmission lines and cables, sequence components of rotating equipment and static load, three-phase models of transformers and conductors, unsymmetrical fault calculations, and some limitations of symmetrical components.

  16. 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.

  17. Homotheties of cylindrically symmetric static spacetimes

    International Nuclear Information System (INIS)

    Qadir, A.; Ziad, M.; Sharif, M.

    1998-08-01

    In this note we consider the homotheties of cylindrically symmetric static spacetimes. We find that we can provide a complete list of all metrics that admit non-trivial homothetic motions and are cylindrically symmetric static. (author)

  18. On convergence completeness in symmetric spaces | Moshokoa ...

    African Journals Online (AJOL)

    convergence complete symmetric space. As applications of convergence completeness, we present some fixed point results for self-maps defined on a symmetric space. Keywords: completeness; convergence completeness; fixed points; metric ...

  19. [Symmetrical lividity of the fingers].

    Science.gov (United States)

    Kocsard, E; Kossard, S

    1988-07-01

    Symmetric lividity of the soles of the feet was first reported in two children in 1925 by Pernet. The characteristic manifestation of this dermatosis consisted in hyperkeratosis and hyperhidrosis with livid discoloration of the pressure areas of the soles. Later the same name was applied to a similar dermatosis in which the hyperkeratotic and hyperhidrotic patches of skin on the soles had a whitish grey discoloration and the livid color, if present at all, was seen only over the marginal areas not affected by the keratosis. Similar livid keratoses affecting the palmar sides of the fingers have been seen only occasionally. The 17-year-old girl presented in this paper had a 11-year history of emotional hyperhidrosis and is a rare illustration of symmetrical lividity in its original form, localized to the fingers only.

  20. Parity-Time Symmetric Photonics

    KAUST Repository

    Zhao, Han

    2018-01-17

    The establishment of non-Hermitian quantum mechanics (such as parity-time (PT) symmetry) stimulates a paradigmatic shift for studying symmetries of complex potentials. Owing to the convenient manipulation of optical gain and loss in analogy to the complex quantum potentials, photonics provides an ideal platform for visualization of many conceptually striking predictions from the non-Hermitian quantum theory. A rapidly developing field has emerged, namely, PT symmetric photonics, demonstrating intriguing optical phenomena including eigenstate coalescence and spontaneous PT symmetry breaking. The advance of quantum physics, as the feedback, provides photonics with brand-new paradigms to explore the entire complex permittivity plane for novel optical functionalities. Here, we review recent exciting breakthroughs in PT symmetric photonics while systematically presenting their underlying principles guided by non-Hermitian symmetries. The potential device applications for optical communication and computing, bio-chemical sensing, and healthcare are also discussed.

  1. Bilateral Symmetrical Parietal Extradural Hematoma

    OpenAIRE

    Agrawal, Amit

    2011-01-01

    The occurrence of bilateral extradural hematomas (EDH) is an uncommon consequence of craniocerebral trauma, and acute symmetrical bilateral epidural hematomas are extremely rare. We discuss the technique adopted by us for the management of this rare entity. A 55-year-old patient presented with history of fall of branch of tree on her head. She had loss of consciousness since then and had multiple episodes of vomiting. Examination of the scalp was suggestive of diffuse subgaleal hematoma. Her ...

  2. Symmetric two-coordinate photodiode

    Directory of Open Access Journals (Sweden)

    Dobrovolskiy Yu. G.

    2008-12-01

    Full Text Available The two-coordinate photodiode is developed and explored on the longitudinal photoeffect, which allows to get the coordinate descriptions symmetric on the steepness and longitudinal resistance great exactness. It was shown, that the best type of the coordinate description is observed in the case of scanning by the optical probe on the central part of the photosensitive element. The ways of improvement of steepness and linear of its coordinate description were analyzed.

  3. Maximally Symmetric Composite Higgs Models.

    Science.gov (United States)

    Csáki, Csaba; Ma, Teng; Shu, Jing

    2017-09-29

    Maximal symmetry is a novel tool for composite pseudo Goldstone boson Higgs models: it is a remnant of an enhanced global symmetry of the composite fermion sector involving a twisting with the Higgs field. Maximal symmetry has far-reaching consequences: it ensures that the Higgs potential is finite and fully calculable, and also minimizes the tuning. We present a detailed analysis of the maximally symmetric SO(5)/SO(4) model and comment on its observational consequences.

  4. Characterization of different types of Nb-AlOx based Josephson tunnel junctions

    International Nuclear Information System (INIS)

    Adelerhof, D.J.; Houwman, E.P.; Fransen, P.B.M.; Veldhuis, D.; Flokstra, J.; Rogalla, H.

    1991-01-01

    This paper reports on three types of Josephson tunnel junctions, standard Nb/Al,AlO x /Nb, symmetric Nb/Al,AlO x /Al/Nb, and Nb/Al,AlO x /AlO x /Nb containing a double oxide layer investigated by means of temperature dependent I-V measurements, conductance-voltage measurements, noise analysis, and Auger Electron Spectroscopy scanning across the edge of a sputtered crater profile. In standard junctions frequently small leakage currents have been observed as well as resistance fluctuations, leading to telegraph noise. Both effects can be related to the direct contact between the AlO x and the Nb counter electrode. In none of the symmetric junctions leakage currents larger than 0.01% of the theoretical maximum critical current have been observed

  5. 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.

  6. Nanoscale E-Cadherin ligand patterns show threshold size for cellular adhesion and adherence junction formation

    DEFF Research Database (Denmark)

    Kristensen, Stine H; Pedersen, Gitte Albinus; Nejsum, Lene Niemann

    2012-01-01

    of adherence junctions in epithelial cells. Cells at 100 nm patterns show poor adhesion, while larger pattern sizes show both good adhesion, significant spreading and defined cortical actin. We estimate a threshold of 0.03μm2 for epithelial cellular attachment via E-Cadherin......The role of ligand spatial distribution on the formation of cadherin mediated cell-cell contacts is studied utilizing nanopatterns of E-cadherin ligands. Protein patches ranging in size from 100 nm to 800 nm prepared by colloidal lithography critically influence adhesion, spreading and formation...

  7. Immanant Conversion on Symmetric Matrices

    Directory of Open Access Journals (Sweden)

    Purificação Coelho M.

    2014-01-01

    Full Text Available Letr Σn(C denote the space of all n χ n symmetric matrices over the complex field C. The main objective of this paper is to prove that the maps Φ : Σn(C -> Σn (C satisfying for any fixed irre- ducible characters X, X' -SC the condition dx(A +aB = dχ·(Φ(Α + αΦ(Β for all matrices A,В ε Σ„(С and all scalars a ε C are automatically linear and bijective. As a corollary of the above result we characterize all such maps Φ acting on ΣИ(С.

  8. Baryon symmetric big bang cosmology

    International Nuclear Information System (INIS)

    Stecker, F.W.

    1978-01-01

    It is stated that the framework of baryon symmetric big bang (BSBB) cosmology offers our greatest potential for deducting the evolution of the Universe because its physical laws and processes have the minimum number of arbitrary assumptions about initial conditions in the big-bang. In addition, it offers the possibility of explaining the photon-baryon ratio in the Universe and how galaxies and galaxy clusters are formed. BSBB cosmology also provides the only acceptable explanation at present for the origin of the cosmic γ-ray background radiation. (author)

  9. Cell-Cell Connection Enhances Proliferation and Neuronal Differentiation of Rat Embryonic Neural Stem/Progenitor Cells

    Directory of Open Access Journals (Sweden)

    Qian Jiao

    2017-07-01

    Full Text Available Cell-cell interaction as one of the niche signals plays an important role in the balance of stem cell quiescence and proliferation or differentiation. In order to address the effect and the possible mechanisms of cell-cell connection on neural stem/progenitor cells (NSCs/NPCs proliferation and differentiation, upon passaging, NSCs/NPCs were either dissociated into single cell as usual (named Group I or mechanically triturated into a mixture of single cell and small cell clusters containing direct cell-cell connections (named Group II. Then the biological behaviors including proliferation and differentiation of NSCs/NPCs were observed. Moreover, the expression of gap junction channel, neurotrophic factors and the phosphorylation status of MAPK signals were compared to investigate the possible mechanisms. Our results showed that, in comparison to the counterparts in Group I, NSCs/NPCs in Group II survived well with preferable neuronal differentiation. In coincidence with this, the expression of connexin 45 (Cx45, as well as brain derived neurotrophic factor (BDNF and neurotrophin 3 (NT-3 in Group II were significantly higher than those in Group I. Phosphorylation of ERK1/2 and JNK2 were significantly upregulated in Group II too, while no change was found about p38. Furthermore, the differences of NSCs/NPCs biological behaviors between Group I and II completely disappeared when ERK and JNK phosphorylation were inhibited. These results indicated that cell-cell connection in Group II enhanced NSCs/NPCs survival, proliferation and neuronal differentiation through upregulating the expression of gap junction and neurotrophic factors. MAPK signals- ERK and JNK might contribute to the enhancement. Efforts for maintaining the direct cell-cell connection are worth making to provide more favorable niches for NSCs/NPCs survival, proliferation and neuronal differentiation.

  10. 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.

  11. Electrical resistivity of monolayers and bilayers of alkanethiols in tunnel junction with gate electrode

    International Nuclear Information System (INIS)

    York, Roger L.; Nacionales, David; Slowinski, Krzysztof

    2005-01-01

    The tunneling resistances of monolayers and bilayers of n-alkanethiols in macroscopic Hg-Hg junctions with an electrochemical gate are reported. The resistances near zero bias calculated per 1 hydrocarbon chain vary from (5 ± 4) x 10 12 Ω for n-nonanethiol to (4 ± 2) x 10 16 Ω for n-octadecanethiol. These values indicate that monolayers of hydrocarbons in Hg-Hg junctions are substantially more resistive as compared to measurements employing microscopic tunnel junctions. The tunneling resistances of monolayer junctions are approximately 1 order of magnitude larger than those of bilayer junctions containing the same number of atoms indicating inefficient electronic coupling across the non-bonded -CH 3 |Hg interface. The symmetric current-voltage curves observed for the asymmetric junctions of Hg-S-(CH 2 ) n -CH 3 |Hg type suggest that these junctions do not behave as molecular diodes. Additional experimental evidence for the nature of the -CH 3 |Hg interface in the Hg-S-(CH 2 ) n -CH 3 |Hg junction is also presented

  12. 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.

  13. 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...

  14. Proteomic and bioinformatic analysis of epithelial tight junction reveals an unexpected cluster of synaptic molecules

    Directory of Open Access Journals (Sweden)

    Tang Vivian W

    2006-12-01

    Full Text Available Abstract Background Zonula occludens, also known as the tight junction, is a specialized cell-cell interaction characterized by membrane "kisses" between epithelial cells. A cytoplasmic plaque of ~100 nm corresponding to a meshwork of densely packed proteins underlies the tight junction membrane domain. Due to its enormous size and difficulties in obtaining a biochemically pure fraction, the molecular composition of the tight junction remains largely unknown. Results A novel biochemical purification protocol has been developed to isolate tight junction protein complexes from cultured human epithelial cells. After identification of proteins by mass spectroscopy and fingerprint analysis, candidate proteins are scored and assessed individually. A simple algorithm has been devised to incorporate transmembrane domains and protein modification sites for scoring membrane proteins. Using this new scoring system, a total of 912 proteins have been identified. These 912 hits are analyzed using a bioinformatics approach to bin the hits in 4 categories: configuration, molecular function, cellular function, and specialized process. Prominent clusters of proteins related to the cytoskeleton, cell adhesion, and vesicular traffic have been identified. Weaker clusters of proteins associated with cell growth, cell migration, translation, and transcription are also found. However, the strongest clusters belong to synaptic proteins and signaling molecules. Localization studies of key components of synaptic transmission have confirmed the presence of both presynaptic and postsynaptic proteins at the tight junction domain. To correlate proteomics data with structure, the tight junction has been examined using electron microscopy. This has revealed many novel structures including end-on cytoskeletal attachments, vesicles fusing/budding at the tight junction membrane domain, secreted substances encased between the tight junction kisses, endocytosis of tight junction

  15. Probabilistic cloning of three symmetric states

    International Nuclear Information System (INIS)

    Jimenez, O.; Bergou, J.; Delgado, A.

    2010-01-01

    We study the probabilistic cloning of three symmetric states. These states are defined by a single complex quantity, the inner product among them. We show that three different probabilistic cloning machines are necessary to optimally clone all possible families of three symmetric states. We also show that the optimal cloning probability of generating M copies out of one original can be cast as the quotient between the success probability of unambiguously discriminating one and M copies of symmetric states.

  16. Microrefrigeration by a pair of normal metal/insulator/superconductor junctions

    Science.gov (United States)

    Leivo, M. M.; Pekola, J. P.; Averin, D. V.

    1995-01-01

    We suggest and demonstrate experimentally that two normal metal/insulator/superconductor (NIS) tunnel junctions combined in series to form a symmetric SINIS structure can operate as an efficient Peltier refrigerator. Specifically, it is shown that the SINIS structure with normal-state junction resistences of 1.0 and 1.1 kOmega is capable of reaching a temperature of about 100 mK starting from 300 mK. We estimate the corresponding cooling power to be 1.5 pW per total junction area of 0.8 micrometers(exp 2) at T = 300 mK. This cooling power density implies that scaling of junction area up to about 1 mm(exp 2) should bring the cooling power into the microW range.

  17. Elliptic annular Josephson tunnel junctions in an external magnetic field: the statics

    DEFF Research Database (Denmark)

    Monaco, Roberto; Granata, Carmine; Vettoliere, Antonio

    2015-01-01

    or in the perpendicular direction. We report a detailed study of both short and long elliptic annular junctions having different eccentricities. For junctions having a normalized perimeter less than one the threshold curves are derived and computed even in the case with one trapped Josephson vortex. For longer junctions...... a numerical analysis is carried out after the derivation of the appropriate perturbed sine-Gordon equation. For a given applied field we find that a number of different phase profiles exist which differ according to the number of fluxon-antifluxon pairs. We demonstrate that in samples made by specularly...... symmetric electrodes a transverse magnetic field is equivalent to an in-plane field applied in the direction of the current flow. Varying the ellipse eccentricity we reproduce all known results for linear and ring-shaped JTJs. Experimental data on high-quality Nb/Al-AlOx/Nb elliptic annular junctions...

  18. Ouabain Increases Gap Junctional Communication in Epithelial Cells

    Directory of Open Access Journals (Sweden)

    Arturo Ponce

    2014-11-01

    Full Text Available Background/Aims: The finding that endogenous ouabain acts as a hormone prompted efforts to elucidate its physiological function. In previous studies, we have shown that 10 nM ouabain (i.e., a concentration within the physiological range modulates cell-cell contacts such as tight junctions and apical/basolateral polarity. In this study, we examined whether 10 nM ouabain affects another important cell-cell feature: gap junction communication (GJC. Methods: We employed two different approaches: 1 analysis of the cell-to-cell diffusion of neurobiotin injected into a particular MDCK cell (epithelial cells from dog kidneys in a confluent monolayer by counting the number of neighboring cells reached by the probe and 2 measurement of the electrical capacitance. Results: We found that 10 nM ouabain increase GJC by 475% within 1 hour. The Na+-K+-ATPase acts as a receptor of ouabain. In previous works we have shown that ouabain activates c-Src and ERK1/2 in 1 hour; in the present study we show that the inhibition of these proteins block the effect of ouabain on GJC. This increase in GJC does not require synthesis of new protein components, because the inhibitors cycloheximide and actinomycin D did not affect this phenomenon. Using silencing assays we also demonstrate that this ouabain-induced enhancement of GJC involves connexins 32 and 43. Conclusion: Ouabain 10 nM increases GJC in MDCK cells.

  19. 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.

  20. Nonlinear PT-symmetric plaquettes

    International Nuclear Information System (INIS)

    Li Kai; Kevrekidis, P G; Malomed, Boris A; Günther, Uwe

    2012-01-01

    We introduce four basic two-dimensional (2D) plaquette configurations with onsite cubic nonlinearities, which may be used as building blocks for 2D PT-symmetric lattices. For each configuration, we develop a dynamical model and examine its PTsymmetry. The corresponding nonlinear modes are analyzed starting from the Hamiltonian limit, with zero value of the gain–loss coefficient, γ. Once the relevant waveforms have been identified (chiefly, in an analytical form), their stability is examined by means of linearization in the vicinity of stationary points. This reveals diverse and, occasionally, fairly complex bifurcations. The evolution of unstable modes is explored by means of direct simulations. In particular, stable localized modes are found in these systems, although the majority of identified solutions are unstable. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Quantum physics with non-Hermitian operators’. (paper)

  1. Classification of symmetric toroidal orbifolds

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Maximilian; Ratz, Michael; Torrado, Jesus [Technische Univ. Muenchen, Garching (Germany). Physik-Department; Vaudrevange, Patrick K.S. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2012-09-15

    We provide a complete classification of six-dimensional symmetric toroidal orbifolds which yield N{>=}1 supersymmetry in 4D for the heterotic string. Our strategy is based on a classification of crystallographic space groups in six dimensions. We find in total 520 inequivalent toroidal orbifolds, 162 of them with Abelian point groups such as Z{sub 3}, Z{sub 4}, Z{sub 6}-I etc. and 358 with non-Abelian point groups such as S{sub 3}, D{sub 4}, A{sub 4} etc. We also briefly explore the properties of some orbifolds with Abelian point groups and N=1, i.e. specify the Hodge numbers and comment on the possible mechanisms (local or non-local) of gauge symmetry breaking.

  2. Spherically symmetric elasticity in relativity

    Energy Technology Data Exchange (ETDEWEB)

    Carot, J [Departament de Fisica, Universitat de les Illes Balears, Cra Valldemossa pk 7.5, E-07122 Palma (Spain); Brito, I; Vaz, E G L R, E-mail: jcarot@uib.ca, E-mail: ireneb@mct.uminho.p, E-mail: evaz@mct.uminho.p

    2010-05-01

    The relativistic theory of elasticity is reviewed within the spherically symmetric context with a view towards the modelling of star interiors possessing elastic properties such as the ones expected in neutron stars. Emphasis is placed on generality in the main sections of the paper, and the results are then applied to specific examples. Along the way, a few general results for spacetimes admitting isometries are deduced, and their consequences are fully exploited in the case of spherical symmetry relating them next to the the case in which the material content of the spacetime is some elastic material. This paper extends and generalizes the pioneering work by Magli and Kijowski [1], Magli [2] and [3], and complements, in a sense, that by Karlovini and Samuelsson in their interesting series of papers [4], [5] and [6].

  3. 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

  4. 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.

  5. 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}.

  6. 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...

  7. 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

  8. Existential-R-Complete Decision Problems about Symmetric Nash Equilibria in Symmetric Multi-Player Games

    OpenAIRE

    Bilò, Vittorio; Mavronicolas, Marios

    2017-01-01

    We study the complexity of decision problems about symmetric Nash equilibria for symmetric multi-player games. These decision problems concern the existence of a symmetric Nash equilibrium with certain natural properties. We show that a handful of such decision problems are Existential-R-complete; that is, they are exactly as hard as deciding the Existential Theory of the Reals.

  9. Cell-matrix and cell-cell interactions of human gingival fibroblasts on three-dimensional nanofibrous gelatin scaffolds.

    Science.gov (United States)

    Sachar, Ashneet; Strom, T Amanda; San Miguel, Symone; Serrano, Maria J; Svoboda, Kathy K H; Liu, Xiaohua

    2014-11-01

    An in-depth understanding of the interactions between cells and three-dimensional (3D) matrices (scaffolds) is pivotal to the development of novel biomaterials for tissue regeneration. However, it remains a challenge to find suitable biomimetic substrates and tools to observe cell-material and cell-cell interactions on 3D matrices. In the present study, we developed biomimetic nanofibrous 3D gelatin scaffolds (3D-NF-GS) and utilized confocal microscopy combined with a quantitative analysis approach to explore cell-matrix and cell-cell interactions on the 3D-NF-GS. Human gingival fibroblasts (HGFs) migrated throughout the 3D-NF-GS by 5 days and formed stable focal adhesions by 14 days. The focal adhesions were detected using integrin-β1, phospho-paxillin and vinculin expression, which were quantified from specific wavelength photon data generated using a spectral separation confocal microscope. As the cells became more confluent after 14 days of culture, cell-cell communication via gap junctions increased significantly. Collagen I matrix production by HGFs on 3D-NF-GS was visualized and quantified using a novel approach incorporating TRITC label in the scaffolds. Based on confocal microscopy, this study has developed qualitative and quantitative methods to study cell-matrix and cell-cell interactions on biomimetic 3D matrices, which provides valuable insights for the development of appropriate scaffolds for tissue regeneration. Copyright © 2012 John Wiley & Sons, Ltd.

  10. Cathepsin G, a Neutrophil Protease, Induces Compact Cell-Cell Adhesion in MCF-7 Human Breast Cancer Cells

    Directory of Open Access Journals (Sweden)

    Tomoya Kudo

    2009-01-01

    Full Text Available Cathepsin G is a serine protease secreted by activated neutrophils that play a role in the inflammatory response. Because neutrophils are known to be invading leukocytes in various tumors, their products may influence the characteristics of tumor cells such as the growth state, motility, and the adhesiveness between cells or the extracellular matrix. Here, we demonstrate that cathepsin G induces cell-cell adhesion of MCF-7 human breast cancer cells resulting from the contact inhibition of cell movement on fibronectin but not on type IV collagen. Cathepsin G subsequently induced cell condensation, a very compact cell colony, resulting due to the increased strength of E-cadherin-mediated cell-cell adhesion. Cathepsin G action is protease activity-dependent and was inhibited by the presence of serine protease inhibitors. Cathepsin G promotes E-cadherin/catenin complex formation and Rap1 activation in MCF-7 cells, which reportedly regulates E-cadherin-based cell-cell junctions. Cathepsin G also promotes E-cadherin/protein kinase D1 (PKD1 complex formation, and Go6976, the selective PKD1 inhibitor, suppressed the cathepsin G-induced cell condensation. Our findings provide the first evidence that cathepsin G regulates E-cadherin function, suggesting that cathepsin G has a novel modulatory role against tumor cell-cell adhesion.

  11. 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.

  12. CANONICAL EXTENSIONS OF SYMMETRIC LINEAR RELATIONS

    NARCIS (Netherlands)

    Sandovici, Adrian; Davidson, KR; Gaspar, D; Stratila, S; Timotin, D; Vasilescu, FH

    2006-01-01

    The concept of canonical extension of Hermitian operators has been recently introduced by A. Kuzhel. This paper deals with a generalization of this notion to the case of symmetric linear relations. Namely, canonical regular extensions of symmetric linear relations in Hilbert spaces are studied. The

  13. On completeness in symmetric spaces | Moshokoa | Quaestiones ...

    African Journals Online (AJOL)

    In the literature completeness for symmetric spaces is done through the classical Cauchy criterion for metric spaces. However, unlike the situation in metric spaces a convergent sequence in a symmetric space is not necessarily a Cauchy sequence. In the paper we introduce a notion of convergence completeness for ...

  14. Generalized geometry and non-symmetric gravity

    OpenAIRE

    Jurco, Branislav; Khoo, Fech Scen; Schupp, Peter; Vysoky, Jan

    2015-01-01

    Generalized geometry provides the framework for a systematic approach to non-symmetric metric gravity theory and naturally leads to an Einstein-Kalb-Ramond gravity theory with totally anti-symmetric contortion. The approach is related to the study of the low-energy effective closed string gravity actions.

  15. Nonlocal Fordy - Kulish Equations on Symmetric Spaces

    OpenAIRE

    Gurses, Metin

    2017-01-01

    We present nonlocal integrable reductions of the Fordy-Kulish system of nonlinear Schrodinger equations and the Fordy system of derivative nonlinear Schrodinger equations on Hermitian symmetric spaces. Examples are given on the symmetric space $\\frac{SU(4)}{SU(2) \\times SU(2)}$.

  16. Spherically symmetric inhomogeneous dust collapse in higher ...

    Indian Academy of Sciences (India)

    We consider a collapsing spherically symmetric inhomogeneous dust cloud in higher dimensional space-time. ... The existence of strong curvature naked singularities in gravitational collapse of spherically symmetric space-times ... where an over dot denotes partial derivative with respect to t. The functions F(r) and f(r).

  17. Substring-Searchable Symmetric Encryption

    Directory of Open Access Journals (Sweden)

    Chase Melissa

    2015-06-01

    Full Text Available In this paper, we consider a setting where a client wants to outsource storage of a large amount of private data and then perform substring search queries on the data – given a data string s and a search string p, find all occurrences of p as a substring of s. First, we formalize an encryption paradigm that we call queryable encryption, which generalizes searchable symmetric encryption (SSE and structured encryption. Then, we construct a queryable encryption scheme for substring queries. Our construction uses suffix trees and achieves asymptotic efficiency comparable to that of unencrypted suffix trees. Encryption of a string of length n takes O(λn time and produces a ciphertext of size O(λn, and querying for a substring of length m that occurs k times takes O(λm+k time and three rounds of communication. Our security definition guarantees correctness of query results and privacy of data and queries against a malicious adversary. Following the line of work started by Curtmola et al. (ACM CCS 2006, in order to construct more efficient schemes we allow the query protocol to leak some limited information that is captured precisely in the definition. We prove security of our substring-searchable encryption scheme against malicious adversaries, where the query protocol leaks limited information about memory access patterns through the suffix tree of the encrypted string.

  18. Baryon symmetric big bang cosmology

    Science.gov (United States)

    Stecker, F. W.

    1978-01-01

    Both the quantum theory and Einsteins theory of special relativity lead to the supposition that matter and antimatter were produced in equal quantities during the big bang. It is noted that local matter/antimatter asymmetries may be reconciled with universal symmetry by assuming (1) a slight imbalance of matter over antimatter in the early universe, annihilation, and a subsequent remainder of matter; (2) localized regions of excess for one or the other type of matter as an initial condition; and (3) an extremely dense, high temperature state with zero net baryon number; i.e., matter/antimatter symmetry. Attention is given to the third assumption, which is the simplest and the most in keeping with current knowledge of the cosmos, especially as pertains the universality of 3 K background radiation. Mechanisms of galaxy formation are discussed, whereby matter and antimatter might have collided and annihilated each other, or have coexisted (and continue to coexist) at vast distances. It is pointed out that baryon symmetric big bang cosmology could probably be proved if an antinucleus could be detected in cosmic radiation.

  19. Charting the Replica Symmetric Phase

    Science.gov (United States)

    Coja-Oghlan, Amin; Efthymiou, Charilaos; Jaafari, Nor; Kang, Mihyun; Kapetanopoulos, Tobias

    2018-02-01

    Diluted mean-field models are spin systems whose geometry of interactions is induced by a sparse random graph or hypergraph. Such models play an eminent role in the statistical mechanics of disordered systems as well as in combinatorics and computer science. In a path-breaking paper based on the non-rigorous `cavity method', physicists predicted not only the existence of a replica symmetry breaking phase transition in such models but also sketched a detailed picture of the evolution of the Gibbs measure within the replica symmetric phase and its impact on important problems in combinatorics, computer science and physics (Krzakala et al. in Proc Natl Acad Sci 104:10318-10323, 2007). In this paper we rigorise this picture completely for a broad class of models, encompassing the Potts antiferromagnet on the random graph, the k-XORSAT model and the diluted k-spin model for even k. We also prove a conjecture about the detection problem in the stochastic block model that has received considerable attention (Decelle et al. in Phys Rev E 84:066106, 2011).

  20. PERIODIC-ORBITS IN K-SYMMETRICAL DYNAMICAL-SYSTEMS

    NARCIS (Netherlands)

    BRANDS, H; LAMB, JSW; HOVEIJN, [No Value

    1995-01-01

    A map L is called k-symmetric if its kth iterate L(k) possesses more symmetry than L, for some value of k. In k-symmetric systems, there exists a notion of k-symmetric orbits. This paper deals with k-symmetric periodic orbits. We derive a relation between orbits that are k-symmetric with respect to

  1. The symmetric extendibility of quantum states

    International Nuclear Information System (INIS)

    Nowakowski, Marcin L

    2016-01-01

    Studies on the symmetric extendibility of quantum states have become particularly important in the context of the analysis of one-way quantum measures of entanglement, and the distillability and security of quantum protocols. In this paper we analyze composite systems containing a symmetric extendible part, with particular attention devoted to the one-way security of such systems. Further, we introduce a new one-way entanglement monotone based on the best symmetric approximation of a quantum state and the extendible number of a quantum state. We underpin these results with geometric observations about the structures of multi-party settings which posses substantial symmetric extendible components in their subspaces. The impossibility of reducing the maximal symmetric extendibility by means of the one-way local operations and classical communication method is pointed out on multiple copies. Finally, we state a conjecture linking symmetric extendibility with the one-way distillability and security of all quantum states, analyzing the behavior of a private key in the neighborhood of symmetric extendible states. (paper)

  2. Crystal structure of a claudin provides insight into the architecture of tight junctions.

    Science.gov (United States)

    Suzuki, Hiroshi; Nishizawa, Tomohiro; Tani, Kazutoshi; Yamazaki, Yuji; Tamura, Atsushi; Ishitani, Ryuichiro; Dohmae, Naoshi; Tsukita, Sachiko; Nureki, Osamu; Fujiyoshi, Yoshinori

    2014-04-18

    Tight junctions are cell-cell adhesion structures in epithelial cell sheets that surround organ compartments in multicellular organisms and regulate the permeation of ions through the intercellular space. Claudins are the major constituents of tight junctions and form strands that mediate cell adhesion and function as paracellular barriers. We report the structure of mammalian claudin-15 at a resolution of 2.4 angstroms. The structure reveals a characteristic β-sheet fold comprising two extracellular segments, which is anchored to a transmembrane four-helix bundle by a consensus motif. Our analyses suggest potential paracellular pathways with distinctive charges on the extracellular surface, providing insight into the molecular basis of ion homeostasis across tight junctions.

  3. Linac design algorithm with symmetric segments

    International Nuclear Information System (INIS)

    Takeda, Harunori; Young, L.M.; Nath, S.; Billen, J.H.; Stovall, J.E.

    1996-01-01

    The cell lengths in linacs of traditional design are typically graded as a function of particle velocity. By making groups of cells and individual cells symmetric in both the CCDTL AND CCL, the cavity design as well as mechanical design and fabrication is simplified without compromising the performance. We have implemented a design algorithm in the PARMILA code in which cells and multi-cavity segments are made symmetric, significantly reducing the number of unique components. Using the symmetric algorithm, a sample linac design was generated and its performance compared with a similar one of conventional design

  4. 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

  5. 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...

  6. 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...

  7. 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.

  8. Cell-cell interactions mediate cytoskeleton organization and collective endothelial cell chemotaxis.

    Science.gov (United States)

    Shamloo, Amir

    2014-09-01

    This study investigates the role of cell-cell and cell-ligand interactions in cytoskeleton organization of endothelial cells (ECs) and their directional migration within a microfluidic device. The migration of ECs in response to a biochemical factor was studied. Mathematical analysis of the cell migration pathways and cellular cytoskeleton revealed that directional migration, migration persistence length, migration speed, and cytoskeletal stress fiber alignment can be mediated by the level of cell contacts as well as the presence or absence of a biochemical polarizing factor. It was shown that in the presence of a biochemical polarizing factor, higher cell density and more frequent cell contacts has a reinforcing effect on collective cell chemotaxis. In contrast, in the absence of a polarizing factor, high cell density can decrease or suppress the ability of the cells to migrate. Also, the correlation of actin stress fiber organization and alignment with directional migration of ECs was investigated. It was shown that in the presence of a biochemical polarizing factor, stress fibers within the cytoskeleton of ECs can be significantly aligned parallel to the gradient direction when the cells have higher level of contacts. The results also show that the organization and alignment of actin stress fibers is mediated by cell adhesion junctions during collective cell migration and introduce cell-cell interactions as a key factor during collective cell chemotaxis. © 2014 Wiley Periodicals, Inc.

  9. 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.

  10. Thermal analysis of two-level wind power converter under symmetrical grid fault

    DEFF Research Database (Denmark)

    Zhou, Dao; Blaabjerg, Frede

    2013-01-01

    In this paper, the case of symmetrical grid fault when using the multi-MW wind turbine of partial-scale and full-scale two-level power converter are designed and investigated. Firstly, the different operation behaviors of the relevant power converters under the voltage dip will be described...... and analyzed. Simulations of different configurations regarding the loss distribution and the junction temperature of the power device are presented in respect to the various voltage dips. It is concluded that for both systems the power loss will change dramatically during the Low-Voltage Ride Through (LVRT......) condition as well as the junction temperature. For the full-scale wind turbine system, the most thermal stressed power device in the grid-side converter will appear at the grid voltage below 0.5 pu, and for the partial-scale wind turbine system, the most thermal stressed power device in the rotor...

  11. Unexpected trapping of particles at a T junction.

    Science.gov (United States)

    Vigolo, Daniele; Radl, Stefan; Stone, Howard A

    2014-04-01

    A common element in physiological flow networks, as well as most domestic and industrial piping systems, is a T junction that splits the flow into two nearly symmetric streams. It is reasonable to assume that any particles suspended in a fluid that enters the bifurcation will leave it with the fluid. Here we report experimental evidence and a theoretical description of a trapping mechanism for low-density particles in steady and pulsatile flows through T-shaped junctions. This mechanism induces accumulation of particles, which can form stable chains, or give rise to significant growth of bubbles due to coalescence. In particular, low-density material dispersed in the continuous phase fluid interacts with a vortical flow that develops at the T junction. As a result suspended particles can enter the vortices and, for a wide range of common flow conditions, the particles do not leave the bifurcation. Via 3D numerical simulations and a model of the two-phase flow we predict the location of particle accumulation, which is in excellent agreement with experimental data. We identify experimentally, as well as confirm by numerical simulations and a simple force balance, that there is a wide parameter space in which this phenomenon occurs. The trapping effect is expected to be important for the design of particle separation and fractionation devices, as well as used for better understanding of system failures in piping networks relevant to industry and physiology.

  12. 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.

  13. Spherically symmetric inhomogeneous dust collapse in higher ...

    Indian Academy of Sciences (India)

    We consider a collapsing spherically symmetric inhomogeneous dust cloud in higher dimensional space-time. We show that the central singularity of collapse can be a strong curvature or a weak curvature naked singularity depending on the initial density distribution.

  14. symmetric sextic potential in two dimensions

    Indian Academy of Sciences (India)

    symmetric sextic potential in two dimensions. FAKIR CHAND1,∗, S C MISHRA1 and RAM MEHAR SINGH2 ... resonance scattering in atomic, molecular, and nuclear physics and to some chemical reactions ...... D R Nelson and N M Snerb, Phys.

  15. Introduction to left-right symmetric models

    International Nuclear Information System (INIS)

    Grimus, W.

    1993-01-01

    We motivate left-right symmetric models by the possibility of spontaneous parity breaking. Then we describe the multiplets and the Lagrangian of such models. Finally we discuss lower bounds on the right-handed scale. (author)

  16. Symmetrical parahiliar infiltrated, cough and dyspnoea

    International Nuclear Information System (INIS)

    Giraldo Estrada, Horacio; Escalante, Hector

    2004-01-01

    It is the case a patient to who is diagnosed symmetrical parahiliar infiltrated; initially she is diagnosed lymphoma Hodgkin, treaty with radiotherapy and chemotherapy, but the X rays of the thorax demonstrated parahiliars and paramediastinals infiltrated

  17. Symmetric nuclear matter with Skyrme interaction

    International Nuclear Information System (INIS)

    Manisa, K.; Bicer, A.; Atav, U.

    2010-01-01

    The equation of state (EOS) and some properties of symmetric nuclear matter, such as the saturation density, saturation energy and incompressibility, are obtained by using Skyrme's density-dependent effective nucleon-nucleon interaction.

  18. Martingale Rosenthal inequalities in symmetric spaces

    Science.gov (United States)

    Astashkin, S. V.

    2014-12-01

    We establish inequalities similar to the classical Rosenthal inequalities for sequences of martingale differences in general symmetric spaces; a central role is played here by the predictable quadratic characteristic of a martingale. Bibliography: 26 titles.

  19. Martingale Rosenthal inequalities in symmetric spaces

    Energy Technology Data Exchange (ETDEWEB)

    Astashkin, S V [Samara State University, Samara (Russian Federation)

    2014-12-31

    We establish inequalities similar to the classical Rosenthal inequalities for sequences of martingale differences in general symmetric spaces; a central role is played here by the predictable quadratic characteristic of a martingale. Bibliography: 26 titles.

  20. Functional Contractive Maps in Triangular Symmetric Spaces

    Directory of Open Access Journals (Sweden)

    Mihai Turinici

    2013-01-01

    Full Text Available Some fixed point results are given for a class of functional contractions acting on (reflexive triangular symmetric spaces. Technical connections with the corresponding theories over (standard metric and partial metric spaces are also being established.

  1. 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

  2. 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

  3. The Naimark dilated PT-symmetric brachistochrone

    OpenAIRE

    Guenther, Uwe; Samsonov, Boris F.

    2008-01-01

    The quantum mechanical brachistochrone system with PT-symmetric Hamiltonian is Naimark dilated and reinterpreted as subsystem of a Hermitian system in a higher-dimensional Hilbert space. This opens a way to a direct experimental implementation of the recently hypothesized PT-symmetric ultra-fast brachistochrone regime of [C. M. Bender et al, Phys. Rev. Lett. {\\bf 98}, 040403 (2007)] in an entangled two-spin system.

  4. Naimark-Dilated PT-Symmetric Brachistochrone

    Science.gov (United States)

    Günther, Uwe; Samsonov, Boris F.

    2008-12-01

    The quantum mechanical brachistochrone system with a PT-symmetric Hamiltonian is Naimark-dilated and reinterpreted as a subsystem of a Hermitian system in a higher-dimensional Hilbert space. This opens a way to a direct experimental implementation of the recently hypothesized PT-symmetric ultrafast brachistochrone regime of Bender et al. [Phys. Rev. Lett. 98, 040403 (2007)PRLTAO0031-900710.1103/PhysRevLett.98.040403] in an entangled two-spin system.

  5. Symmetric states: Their nonlocality and entanglement

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zizhu; Markham, Damian [CNRS LTCI, Département Informatique et Réseaux, Telecom ParisTech, 23 avenue d' Italie, CS 51327, 75214 Paris CEDEX 13 (France)

    2014-12-04

    The nonlocality of permutation symmetric states of qubits is shown via an extension of the Hardy paradox and the extension of the associated inequality. This is achieved by using the Majorana representation, which is also a powerful tool in the study of entanglement properties of symmetric states. Through the Majorana representation, different nonlocal properties can be linked to different entanglement properties of a state, which is useful in determining the usefulness of different states in different quantum information processing tasks.

  6. Molecular Motion of the Junction Points in Model Networks Prepared by Acyclic Triene Metathesis.

    Science.gov (United States)

    da Silva, Lucas Caire; Bowers, Clifford R; Graf, Robert; Wagener, Kenneth B

    2016-03-01

    The junction dynamics in a selectively deuterated model polymer network containing junctions on every 21st chain carbon is studied by solid state (2) H echo NMR. Polymer networks are prepared via acyclic triene metathesis of deuteron-labeled symmetric trienes with deuteron probes precisely placed at the alpha carbon relative to the junction point. The effect of decreasing the cross-link density on the junction dynamics is studied by introduction of polybutadiene chains in-between junctions. The networks are characterized by swelling, gel content, and solid state (1) H MAS NMR. Line shape analysis of the (2) H quadrupolar echo spectra reveals that the degree of motion anisotropy and the distribution of motion correlation times depend on the cross-link density and structural heterogeneity of the polymer networks. A detailed model of the junction dynamics at different temperatures is proposed and explained in terms of the intermolecular cooperativity in densely-packed systems. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Droplet Breakup in Asymmetric T-Junctions at Intermediate to Large Capillary Numbers

    Science.gov (United States)

    Sadr, Reza; Cheng, Way Lee

    2017-11-01

    Splitting of a parent droplet into multiple daughter droplets of desired sizes is usually desired to enhance production and investigational efficiency in microfluidic devices. This can be done in an active or passive mode depending on whether an external power sources is used or not. In this study, three-dimensional simulations were done using the Volume-of-Fluid (VOF) method to analyze droplet splitting in asymmetric T-junctions with different outlet lengths. The parent droplet is divided into two uneven portions the volumetric ratio of the daughter droplets, in theory, depends on the length ratios of the outlet branches. The study identified various breakup modes such as primary, transition, bubble and non-breakup under various flow conditions and the configuration of the T-junctions. In addition, an analysis with the primary breakup regimes were conducted to study the breakup mechanisms. The results show that the way the droplet splits in an asymmetric T-junction is different than the process in a symmetric T-junction. A model for the asymmetric breakup criteria at intermediate or large Capillary number is presented. The proposed model is an expanded version to a theoretically derived model for the symmetric droplet breakup under similar flow conditions.

  8. Oxidative Stress, Signal Transduction, Cell-Cell Communication

    National Research Council Canada - National Science Library

    Trosko, James

    1999-01-01

    .... The integration of intercellular communication through gap junctions and intracellular pathways plays a role in maintaining the homeostasis by controlling the expression of genes that control cell...

  9. 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

  10. 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.

  11. Junctional adhesion molecule-A: functional diversity through molecular promiscuity.

    Science.gov (United States)

    Steinbacher, Tim; Kummer, Daniel; Ebnet, Klaus

    2017-12-14

    Cell adhesion molecules (CAMs) of the immunoglobulin superfamily (IgSF) regulate important processes such as cell proliferation, differentiation and morphogenesis. This activity is primarily due to their ability to initiate intracellular signaling cascades at cell-cell contact sites. Junctional adhesion molecule-A (JAM-A) is an IgSF-CAM with a short cytoplasmic tail that has no catalytic activity. Nevertheless, JAM-A is involved in a variety of biological processes. The functional diversity of JAM-A resides to a large part in a C-terminal PDZ domain binding motif which directly interacts with nine different PDZ domain-containing proteins. The molecular promiscuity of its PDZ domain motif allows JAM-A to recruit protein scaffolds to specific sites of cell-cell adhesion and to assemble signaling complexes at those sites. Here, we review the molecular characteristics of JAM-A, including its dimerization, its interaction with scaffolding proteins, and the phosphorylation of its cytoplasmic domain, and we describe how these characteristics translate into diverse biological activities.

  12. 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.

  13. G-Strands on symmetric spaces

    Science.gov (United States)

    2017-01-01

    We study the G-strand equations that are extensions of the classical chiral model of particle physics in the particular setting of broken symmetries described by symmetric spaces. These equations are simple field theory models whose configuration space is a Lie group, or in this case a symmetric space. In this class of systems, we derive several models that are completely integrable on finite dimensional Lie group G, and we treat in more detail examples with symmetric space SU(2)/S1 and SO(4)/SO(3). The latter model simplifies to an apparently new integrable nine-dimensional system. We also study the G-strands on the infinite dimensional group of diffeomorphisms, which gives, together with the Sobolev norm, systems of 1+2 Camassa–Holm equations. The solutions of these equations on the complementary space related to the Witt algebra decomposition are the odd function solutions. PMID:28413343

  14. All-optical symmetric ternary logic gate

    Science.gov (United States)

    Chattopadhyay, Tanay

    2010-09-01

    Symmetric ternary number (radix=3) has three logical states (1¯, 0, 1). It is very much useful in carry free arithmetical operation. Beside this, the logical operation using this type of number system is also effective in high speed computation and communication in multi-valued logic. In this literature all-optical circuits for three basic symmetrical ternary logical operations (inversion, MIN and MAX) are proposed and described. Numerical simulation verifies the theoretical model. In this present scheme the different ternary logical states are represented by different polarized state of light. Terahertz optical asymmetric demultiplexer (TOAD) based interferometric switch has been used categorically in this manuscript.

  15. A Relativistic Symmetrical Interpretation of Quantum Mechanics

    Science.gov (United States)

    Heaney, Michael B.

    This poster describes a relativistic symmetrical interpretation (RSI) which postulates: quantum mechanics is intrinsically time-symmetric, with no arrow of time; the fundamental objects of quantum mechanics are transitions; a transition is fully described by a complex transition amplitude density with specified initial and final boundary conditions, and; transition amplitude densities never collapse. This RSI is compared to the Copenhagen Interpretation (CI) for the analysis of Einstein's bubble experiment using both the Dirac and Klein-Gordon equations. The RSI has no zitterbewegung in the particle's rest frame, resolves some inconsistencies of the CI, and gives intuitive explanations of some previously mysterious quantum effects.

  16. Symmetry theorems via the continuous steiner symmetrization

    Directory of Open Access Journals (Sweden)

    L. Ragoub

    2000-06-01

    Full Text Available Using a new approach due to F. Brock called the Steiner symmetrization, we show first that if $u$ is a solution of an overdetermined problem in the divergence form satisfying the Neumann and non-constant Dirichlet boundary conditions, then $Omega$ is an N-ball. In addition, we show that we can relax the condition on the value of the Dirichlet boundary condition in the case of superharmonicity. Finally, we give an application to positive solutions of some semilinear elliptic problems in symmetric domains for the divergence case.

  17. 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.)

  18. MARCKS-related protein regulates cytoskeletal organization at cell-cell and cell-substrate contacts in epithelial cells.

    Science.gov (United States)

    Van Itallie, Christina M; Tietgens, Amber Jean; Aponte, Angel; Gucek, Marjan; Cartagena-Rivera, Alexander X; Chadwick, Richard S; Anderson, James M

    2018-02-02

    Treatment of epithelial cells with interferon-γ and TNF-α (IFN/TNF) results in increased paracellular permeability. To identify relevant proteins mediating barrier disruption, we performed proximity-dependent biotinylation (BioID) of occludin and found that tagging of MARCKS-related protein (MRP; also known as MARCKSL1) increased ∼20-fold following IFN/TNF administration. GFP-MRP was focused at the lateral cell membrane and its overexpression potentiated the physiological response of the tight junction barrier to cytokines. However, deletion of MRP did not abrogate the cytokine responses, suggesting that MRP is not required in the occludin-dependent IFN/TNF response. Instead, our results reveal a key role for MRP in epithelial cells in control of multiple actin-based structures, likely by regulation of integrin signaling. Changes in focal adhesion organization and basal actin stress fibers in MRP-knockout (KO) cells were reminiscent of those seen in FAK-KO cells. In addition, we found alterations in cell-cell interactions in MRP-KO cells associated with increased junctional tension, suggesting that MRP may play a role in focal adhesion-adherens junction cross talk. Together, our results are consistent with a key role for MRP in cytoskeletal organization of cell contacts in epithelial cells. © 2018. Published by The Company of Biologists Ltd.

  19. 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....

  20. 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

  1. 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....

  2. 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.

  3. 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...

  4. Mechanical properties of DNA origami nanoassemblies are determined by Holliday junction mechanophores.

    Science.gov (United States)

    Shrestha, Prakash; Emura, Tomoko; Koirala, Deepak; Cui, Yunxi; Hidaka, Kumi; Maximuck, William J; Endo, Masayuki; Sugiyama, Hiroshi; Mao, Hanbin

    2016-08-19

    DNA nanoassemblies have demonstrated wide applications in various fields including nanomaterials, drug delivery and biosensing. In DNA origami, single-stranded DNA template is shaped into desired nanostructure by DNA staples that form Holliday junctions with the template. Limited by current methodologies, however, mechanical properties of DNA origami structures have not been adequately characterized, which hinders further applications of these materials. Using laser tweezers, here, we have described two mechanical properties of DNA nanoassemblies represented by DNA nanotubes, DNA nanopyramids and DNA nanotiles. First, mechanical stability of DNA origami structures is determined by the effective density of Holliday junctions along a particular stress direction. Second, mechanical isomerization observed between two conformations of DNA nanotubes at 10-35 pN has been ascribed to the collective actions of individual Holliday junctions, which are only possible in DNA origami with rotational symmetric arrangements of Holliday junctions, such as those in DNA nanotubes. Our results indicate that Holliday junctions control mechanical behaviors of DNA nanoassemblies. Therefore, they can be considered as 'mechanophores' that sustain mechanical properties of origami nanoassemblies. The mechanical properties observed here provide insights for designing better DNA nanostructures. In addition, the unprecedented mechanical isomerization process brings new strategies for the development of nano-sensors and actuators. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

  5. PT -symmetric model of immune response

    Science.gov (United States)

    Bender, Carl M.; Ghatak, Ananya; Gianfreda, Mariagiovanna

    2017-01-01

    The study of PT -symmetric physical systems began in 1998 as a complex generalization of conventional quantum mechanics, but beginning in 2007 experiments began to be published in which the predicted PT phase transition was clearly observed in classical rather than in quantum-mechanical systems. This paper examines the classical PT phase transition in dynamical-system models that are moderately accurate representations of antigen-antibody systems. A surprising conclusion that can be drawn from these models is that it might be possible treat a serious disease in which the antigen concentration grows out of bounds (and the host dies) by injecting a small dose of a second (different) antigen. In this case a PT -symmetric analysis shows there are two possible favorable outcomes. In the unbroken-PT -symmetric phase the disease becomes chronic and is no longer lethal, while in the appropriate broken-PT -symmetric phase the concentration of lethal antigen goes to zero and the disease is completely cured.

  6. Progressive symmetric exfoliative ichthyosis | Al Aboud | Sudanese ...

    African Journals Online (AJOL)

    We report an 11–year-old girl with well defined ichthyosiform patches on extremities. There is a history of similar condition in her cousin. We believe that this case represent a new autosomal recessive disorder of cornification that may be better refer to it as ''progressive symmetric exfoliative ichthyosis''. Sudanese Journal of ...

  7. Symmetric intersections of Rauzy fractals | Sellami | Quaestiones ...

    African Journals Online (AJOL)

    In this article we study symmetric subsets of Rauzy fractals of unimodular irreducible Pisot substitutions. The symmetry considered is re ection through the origin. Given an unimodular irreducible Pisot substitution, we consider the intersection of its Rauzy fractal with the Rauzy fractal of the reverse substitution. This set is ...

  8. A viewpoint on nearly conformally symmetric manifold

    International Nuclear Information System (INIS)

    Rahman, M.S.

    1990-06-01

    Some observations, with definition, on Nearly Conformally Symmetric (NCS) manifold are made. A number of theorems concerning conformal change of metric and parallel tensors on NCS manifolds are presented. It is illustrated that a manifold M = R n-1 x R + 1 , endowed with a special metric, is NCS but not of harmonic curvature. (author). 8 refs

  9. Biomechanical benefits of symmetrical strengthening of hip ...

    African Journals Online (AJOL)

    There is abundant literature encouraging athletes to engage in concurrent strength training. However, little emphasis is placed on the value of biomechanics with regard to symmetrical strengthening of force-couple relationships. A review of literature reveals 565 biomechanical papers versus 2085 physiological papers ...

  10. Cuspidal discrete series for semisimple symmetric spaces

    DEFF Research Database (Denmark)

    Andersen, Nils Byrial; Flensted-Jensen, Mogens; Schlichtkrull, Henrik

    2012-01-01

    We propose a notion of cusp forms on semisimple symmetric spaces. We then study the real hyperbolic spaces in detail, and show that there exists both cuspidal and non-cuspidal discrete series. In particular, we show that all the spherical discrete series are non-cuspidal. (C) 2012 Elsevier Inc. All...

  11. Bilateral Symmetrical Parietal Extradural Hematoma | Agrawal ...

    African Journals Online (AJOL)

    is an uncommon consequence of craniocerebral trauma, and acute symmetrical bilateral epidural hematomas are extremely rare. We discuss the technique ... A 55-year-old patient presented with history of fall of branch of tree on her head. She had loss of ... Initially, left parietal trephine craniotomy was performed and ...

  12. Efficient and convenient synthesis of symmetrical carboxylic ...

    African Journals Online (AJOL)

    An efficient and convenient procedure for the synthesis of symmetrical carboxylic anhydrides from carboxylic acids with sulfated zirconia by PEG-1000 phase transfer catalysis has been developed. The reactions proceeded under mild and solvent-free conditions to provide the carboxylic anhydrides in good to excellent ...

  13. Unary self-verifying symmetric difference automata

    CSIR Research Space (South Africa)

    Marais, Laurette

    2016-07-01

    Full Text Available We investigate self-verifying nondeterministic finite automata, in the case of unary symmetric difference nondeterministic finite automata (SV-XNFA). We show that there is a family of languages Ln=2 which can always be represented non...

  14. Exact solutions of the spherically symmetric multidimensional ...

    African Journals Online (AJOL)

    The complete orthonormalised energy eigenfunctions and the energy eigenvalues of the spherically symmetric isotropic harmonic oscillator in N dimensions, are obtained through the methods of separation of variables. Also, the degeneracy of the energy levels are examined. KEY WORDS: - Schrödinger Equation, Isotropic ...

  15. Prevalence and incidence of symmetrical symptomatic peripheral ...

    African Journals Online (AJOL)

    Background. Symptomatic symmetrical peripheral neuropathy (SSPN) is common in patients with HIV infection. It is also a common adverse event associated with both tuberculosis (TB) treatment and antiretroviral therapy (ART), particularly stavudine. While tenofovir is the one of recommended first-line nucleotide reverse ...

  16. Symmetric corticobasal degeneration (S-CBD).

    Science.gov (United States)

    Hassan, Anhar; Whitwell, Jennifer L; Boeve, Bradley F; Jack, Clifford R; Parisi, Joseph E; Dickson, Dennis W; Josephs, Keith A

    2010-03-01

    Corticobasal degeneration (CBD) is a neurodegenerative disease characterized pathologically by neuronal loss, gliosis and tau deposition in neocortex, basal ganglia and brainstem. Typical clinical presentation is known as corticobasal syndrome (CBS) and involves the core features of progressive asymmetric rigidity and apraxia, accompanied by other signs of cortical and extrapyramidal dysfunction. Asymmetry is also emphasized on neuroimaging. To describe a series of cases of CBD with symmetric clinical features and to compare clinical and imaging features of these symmetric CBD cases (S-CBD) to typical cases of CBS with CBD pathology. All cases of pathologically confirmed CBD from the Mayo Clinic Rochester database were identified. Clinical records were reviewed and quantitative volumetric analysis of symmetric atrophy on head MRI using atlas based parcellation was performed. Subjects were classified as S-CBD if no differences had been observed between right- and left-sided cortical or extrapyramidal signs or symptoms. S-CBD cases were compared to 10 randomly selected typical CBS cases. Five cases (2 female) met criteria for S-CBD. None had limb dystonia, myoclonus, apraxia or alien limb phenomena. S-CBD cases had significantly less asymmetric atrophy when compared with CBS cases (p=0.009); they were also younger at onset (median 61 versus 66 years, pCBD cases. CBD can have a symmetric presentation, clinically and radiologically, in which typical features of CBS, such as limb apraxia, myoclonus, dystonia and alien limb phenomenon, may be absent. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

  17. efficient and convenient synthesis of symmetrical carboxylic

    African Journals Online (AJOL)

    Preferred Customer

    strong acidity and high activity in light alkane conversions at relatively mild temperatures [36,. 37]. In this paper, we wish to report an efficient and convenient method for the preparation of symmetrical carboxylic anhydrides from the corresponding carboxylic acids with sulfated zirconia by phase transfer catalysis without any ...

  18. Picosecond optical nonlinearities in symmetrical and unsymmetrical ...

    Indian Academy of Sciences (India)

    We present our experimental results on the picosecond nonlinear optical. (NLO) studies of symmetrical and unsymmetrical phthalocyanines, examined using the. Z-scan technique. Both the open-aperture ... Z-scan measurements were performed using the amplified Ti:sapphire laser system. (LEGEND, Coherent) delivering ...

  19. Spectrum generating algebra of the symmetric top

    Energy Technology Data Exchange (ETDEWEB)

    Bijker, R. [Universidad Nacional Autonoma de Mexico, Mexico City (Mexico). Inst. de Ciencias Nucleares; Leviatan, A. [Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel)

    1998-03-02

    We consider an algebraic treatment of a three-body system. We develop the formalism for a system of three identical objects and show that it provides a simultaneous description of the vibrational and rotational excitations of an oblate symmetric top. (orig.) 8 refs.

  20. Spectrum generating algebra of the symmetric top

    International Nuclear Information System (INIS)

    Bijker, R.

    1998-01-01

    We consider an algebraic treatment of a three-body system. We develop the formalism for a system of three identical objects and show that it provides a simultaneous description of the vibrational and rotational excitations of an oblate symmetric top. (orig.)

  1. The symmetric Mellin transform in quantum calculus

    Directory of Open Access Journals (Sweden)

    Brahim Kamel Brahim

    2015-12-01

    Full Text Available In this paper, we define the q-analogue of Mellin Transform symmetric under interchange of q and 1/q, and present some of its main properties and explore the possibility of using the integral transform to solve a class of differential equations q-differences.

  2. Fourier transforms on a semisimple symmetric space

    NARCIS (Netherlands)

    Ban, E.P. van den; Schlichtkrull, H.

    1994-01-01

    Let G=H be a semisimple symmetric space, that is, G is a connected semisimple real Lie group with an involution ?, and H is an open subgroup of the group of xed points for ? in G. The main purpose of this paper is to study an explicit Fourier transform on G=H. In terms of general representation

  3. Fourier transforms on a semisimple symmetric space

    NARCIS (Netherlands)

    Ban, E.P. van den; Carmona, J.; Delorme, P.

    1997-01-01

    Let G=H be a semisimple symmetric space, that is, G is a connected semisimple real Lie group with an involution ?, and H is an open subgroup of the group of xed points for ? in G. The main purpose of this paper is to study an explicit Fourier transform on G=H. In terms of general representation

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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 ...

  10. 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

  11. 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.

  12. Symmetrical lividity of the palms and soles.

    Science.gov (United States)

    Rietschel, R L; Carr, J F; Lewis, C W

    1978-11-01

    Symmetrical lividity (SL) was the term coined by Pernet in 1925 for symmetrical, bluish-red plaques on the soles of the feet, accompanied by hyperhidrosis and not corresponding to areas of pressure or patterns of innervation. We report two patients with a persistent eruption of the palms analogous to that described by Pernet on the feet. Unlike most reported cases of SL, our patients did not respond to topical drying treatments, but one patient partially responded to tretinoin. There appear to be two forms of SL: transient, which responds to drying; and persistent which does not respond to drying. The hyperhidrosis studied in one of our two patients was significantly greater within the plaques of SL than the normal palm. While we could suppress the hyperhidrosis with topical therapy, this failed to clear his hyperkeratosis or eliminate the livid color.

  13. Phenomenology of quark-lepton symmetric models

    International Nuclear Information System (INIS)

    Foot, R.; Lew, H.; Volkas

    1991-01-01

    Quark-lepton symmetric models are a new class of gauge theories which unify the quarks and leptons. In these models the gauge group of the standard model is extended to include a color group for the leptons, and consequently the quarks and leptons can then be related by a Z 2 discrete quark-lepton symmetry. Phenomenological implications of these theories are explored. Two varieties are analysed: one being the simplest quark-lepton symmetric model, and the other containing conventional left-right symmetry. Each theory has a Z' boson, whose masses are constrained at 90% C.L. to be greater than 700 GeV and 650 GeV respectively. Phenomenological constraints from rare decays and the implications of the extended fermion spectrum are also examined. 37 refs., 2 tabs

  14. Symmetric, discrete fractional splines and Gabor systems

    DEFF Research Database (Denmark)

    Søndergaard, Peter Lempel

    2006-01-01

    In this paper we consider fractional splines as windows for Gabor frames. We introduce two new types of symmetric, fractional splines in addition to one found by Unser and Blu. For the finite, discrete case we present two families of splines: One is created by sampling and periodizing the continu......In this paper we consider fractional splines as windows for Gabor frames. We introduce two new types of symmetric, fractional splines in addition to one found by Unser and Blu. For the finite, discrete case we present two families of splines: One is created by sampling and periodizing...... the continuous splines, and one is a truly finite, discrete construction. We discuss the properties of these splines and their usefulness as windows for Gabor frames and Wilson bases....

  15. Symmetric configurations highlighted by collective quantum coherence

    Energy Technology Data Exchange (ETDEWEB)

    Obster, Dennis [Radboud University, Institute for Mathematics, Astrophysics and Particle Physics, Nijmegen (Netherlands); Kyoto University, Yukawa Institute for Theoretical Physics, Kyoto (Japan); Sasakura, Naoki [Kyoto University, Yukawa Institute for Theoretical Physics, Kyoto (Japan)

    2017-11-15

    Recent developments in quantum gravity have shown the Lorentzian treatment to be a fruitful approach towards the emergence of macroscopic space-times. In this paper, we discuss another related aspect of the Lorentzian treatment: we argue that collective quantum coherence may provide a simple mechanism for highlighting symmetric configurations over generic non-symmetric ones. After presenting the general framework of the mechanism, we show the phenomenon in some concrete simple examples in the randomly connected tensor network, which is tightly related to a certain model of quantum gravity, i.e., the canonical tensor model. We find large peaks at configurations invariant under Lie-group symmetries as well as a preference for charge quantization, even in the Abelian case. In future study, this simple mechanism may provide a way to analyze the emergence of macroscopic space-times with global symmetries as well as various other symmetries existing in nature, which are usually postulated. (orig.)

  16. Representations of the infinite symmetric group

    CERN Document Server

    Borodin, Alexei

    2016-01-01

    Representation theory of big groups is an important and quickly developing part of modern mathematics, giving rise to a variety of important applications in probability and mathematical physics. This book provides the first concise and self-contained introduction to the theory on the simplest yet very nontrivial example of the infinite symmetric group, focusing on its deep connections to probability, mathematical physics, and algebraic combinatorics. Following a discussion of the classical Thoma's theorem which describes the characters of the infinite symmetric group, the authors describe explicit constructions of an important class of representations, including both the irreducible and generalized ones. Complete with detailed proofs, as well as numerous examples and exercises which help to summarize recent developments in the field, this book will enable graduates to enhance their understanding of the topic, while also aiding lecturers and researchers in related areas.

  17. Factored Facade Acquisition using Symmetric Line Arrangements

    KAUST Repository

    Ceylan, Duygu

    2012-05-01

    We introduce a novel framework for image-based 3D reconstruction of urban buildings based on symmetry priors. Starting from image-level edges, we generate a sparse and approximate set of consistent 3D lines. These lines are then used to simultaneously detect symmetric line arrangements while refining the estimated 3D model. Operating both on 2D image data and intermediate 3D feature representations, we perform iterative feature consolidation and effective outlier pruning, thus eliminating reconstruction artifacts arising from ambiguous or wrong stereo matches. We exploit non-local coherence of symmetric elements to generate precise model reconstructions, even in the presence of a significant amount of outlier image-edges arising from reflections, shadows, outlier objects, etc. We evaluate our algorithm on several challenging test scenarios, both synthetic and real. Beyond reconstruction, the extracted symmetry patterns are useful towards interactive and intuitive model manipulations.

  18. Resistor Networks based on Symmetrical Polytopes

    Directory of Open Access Journals (Sweden)

    Jeremy Moody

    2015-03-01

    Full Text Available This paper shows how a method developed by Van Steenwijk can be generalized to calculate the resistance between any two vertices of a symmetrical polytope all of whose edges are identical resistors. The method is applied to a number of cases that have not been studied earlier such as the Archimedean polyhedra and their duals in three dimensions, the regular polytopes in four dimensions and the hypercube in any number of dimensions.

  19. Irreducible complexity of iterated symmetric bimodal maps

    Directory of Open Access Journals (Sweden)

    J. P. Lampreia

    2005-01-01

    Full Text Available We introduce a tree structure for the iterates of symmetric bimodal maps and identify a subset which we prove to be isomorphic to the family of unimodal maps. This subset is used as a second factor for a ∗-product that we define in the space of bimodal kneading sequences. Finally, we give some properties for this product and study the ∗-product induced on the associated Markov shifts.

  20. Quantum unharmonic symmetrical oscillators using elliptic functions

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, A.M.; Bejarano, J.d.

    1986-04-21

    The authors study in the JWKB approximation the energy levels of the symmetric anharmonic oscillators V(x) Ax/sup 2/ + Bx/sup 4/ for different signs and values of A and B. Comparisons are made with published results for specific cases and with numerical calculations. An additional example is given of exact value, to add to the very rare catalogue of known examples.

  1. M-curves and symmetric products

    Indian Academy of Sciences (India)

    Indranil Biswas

    2017-08-03

    Aug 3, 2017 ... Since M-curves play a special role in the topology of real algebraic varieties, it is useful to have a criterion for M-curves. It was proved earlier that a curve defined over R is an. M-curve if and only if its Jacobian is an M-variety [5]. We use this result of [5] and the. Picard bundle to prove that the n-th symmetric ...

  2. Symmetric Wilson Loops beyond leading order

    Directory of Open Access Journals (Sweden)

    Xinyi Chen-Lin

    2016-12-01

    Full Text Available We study the circular Wilson loop in the symmetric representation of U(N in $\\mathcal{N} = 4$ super-Yang-Mills (SYM. In the large N limit, we computed the exponentially-suppressed corrections for strong coupling, which suggests non-perturbative physics in the dual holographic theory. We also computed the next-to-leading order term in 1/N, and the result matches with the exact result from the k-fundamental representation.

  3. Equivariant embeddings of Hermitian symmetric spaces

    Indian Academy of Sciences (India)

    It is natural to expect these to be preserved. The embedding of the symmetric space for. SU(p, 1), Xp,1, into XP ,Q where P = (p k. ) , Q = ( p k−1. ) [8] gives a very graphic example. Another strong motivation for the theorem is given by Mok's rigidity results. Assume for simplicity that H is irreducible over Q and rk(H) > 1 (this is ...

  4. Dirichlet forms and symmetric Markov processes

    CERN Document Server

    Oshima, Yoichi; Fukushima, Masatoshi

    2010-01-01

    Since the publication of the first edition in 1994, this book has attracted constant interests from readers and is by now regarded as a standard reference for the theory of Dirichlet forms. For the present second edition, the authors not only revised the existing text, but also added some new sections as well as several exercises with solutions. The book addresses to researchers and graduate students who wish to comprehend the area of Dirichlet forms and symmetric Markov processes.

  5. Is the Universe matter-antimatter symmetric

    International Nuclear Information System (INIS)

    Alfven, H.

    1976-09-01

    According to the symmetric cosmology there should be antimatter regions in space which are equally as large as the matter regions. The regions of different kind are separated by Leidenfrost layers, which may be very thin and not observable from a distance. This view has met resistance which in part is based on the old view that the dilute interstellar and intergalactic medium is more or less homogeneous. However, through space research in the magnetosphere and interplanetary space we know that thin layers, dividing space into regions of different magnetisation, exist and based on this it is concluded that space in general has a cellular structure. This result may break down the psychological resistance to the symmetric theory. The possibility that every second star in our galaxy consists of antimatter is discussed, and it is shown that this view is not in conflict with any observations. As most stars are likely to be surrounded by solar systems of a structure like our own, it is concluded that collisions between comets and antistars (or anticomets and stars) would be rather frequent. Such collisions would result in phenomena of the same type as the observed cosmic γ-ray bursts. Another support for the symmetric cosmology is the continuous X-ray background radiation. Also many of the observed large energy releases in cosmos are likely to be due to annihilation

  6. On the harmonic starlike functions with respect to symmetric ...

    African Journals Online (AJOL)

    In the present paper, we introduce the notions of functions harmonic starlike with respect to symmetric, conjugate and symmetric conjugate points. Such results as coefficient inequalities and structural formulae for these function classes are proved. Keywords: Harmonic functions, harmonic starlike functions, symmetric points, ...

  7. Curcumin does not alter the phorbol ester effect on cell-cell transfer of lucifer yellow CH.

    Science.gov (United States)

    Pásti, G; Kertai, P; Adány, R

    1995-05-01

    Curcumin, the dietary pigment responsible for the yellow color of curry, has been reported to be a potent inhibitor of tumor promotion in mouse epidermis. Since most tumor promoters inhibit cell-cell communication, we have examined the effect of curcumin on the reduction of gap junctional intercellular communication induced by the phorbol ester phorbol-12,13-dibutyrate (PDBu) in BALB/c 3T3 cells. Treatment of cells with 50 microM curcumin slightly inhibited the dye coupling evaluated by intercellular transfer of a fluorescent dye Lucifer Yellow CH; however, lower concentrations of curcumin did not affect the level of intercellular communication. Addition of 200 nM PDBu caused a rapid reduction of dye coupling, which was not altered by either pretreatment or simultaneous curcumin addition.

  8. Llgl1 Connects Cell Polarity with Cell-Cell Adhesion in Embryonic Neural Stem Cells.

    Science.gov (United States)

    Jossin, Yves; Lee, Minhui; Klezovitch, Olga; Kon, Elif; Cossard, Alexia; Lien, Wen-Hui; Fernandez, Tania E; Cooper, Jonathan A; Vasioukhin, Valera

    2017-06-05

    Malformations of the cerebral cortex (MCCs) are devastating developmental disorders. We report here that mice with embryonic neural stem-cell-specific deletion of Llgl1 (Nestin-Cre/Llgl1 fl/fl ), a mammalian ortholog of the Drosophila cell polarity gene lgl, exhibit MCCs resembling severe periventricular heterotopia (PH). Immunohistochemical analyses and live cortical imaging of PH formation revealed that disruption of apical junctional complexes (AJCs) was responsible for PH in Nestin-Cre/Llgl1 fl/fl brains. While it is well known that cell polarity proteins govern the formation of AJCs, the exact mechanisms remain unclear. We show that LLGL1 directly binds to and promotes internalization of N-cadherin, and N-cadherin/LLGL1 interaction is inhibited by atypical protein kinase C-mediated phosphorylation of LLGL1, restricting the accumulation of AJCs to the basolateral-apical boundary. Disruption of the N-cadherin-LLGL1 interaction during cortical development in vivo is sufficient for PH. These findings reveal a mechanism responsible for the physical and functional connection between cell polarity and cell-cell adhesion machineries in mammalian cells. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. [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.

  10. 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.

  11. 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

  12. 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

  13. Distributions of chain ends and junction points in ordered block copolymers

    International Nuclear Information System (INIS)

    Mayes, A.M.; Johnson, R.D.; Russell, T.P.; Smith, S.D.; Satija, S.K.; Majkrzak, C.F.

    1993-01-01

    Chain configurations in ordered symmetric poly(styrene-b-methyl methacrylate) diblock copolymers were examined by neutron reflectively. In a thin-film geometry the copolymers organize into lamellar microdomains oriented parallel to the substrate surface. The copolymers organize into lamellar microdomains oriented parallel to the substrate surface. The copolymers were synthesized with small fractions of deuterated segments at either the chain ends or centers. This selective labeling permitted characterization of the spatial distribution of chain ends and junction points normal to the plane of the film. From the reflectivity analysis, the junction points are found to be confined to the PS/PMMA interfacial regions. The chain ends, however, are well distributed through their respective domains, exhibiting only a weak maximum in concentration at the center of the domains

  14. MRI gel dosimetry for verification of mono-isocentric junction doses in head and neck radiotherapy

    International Nuclear Information System (INIS)

    Back, S.A.J.; Jayasekera, P.M.; Lepage, M.; Baldock, C.; Menzies, N.; Back, P.

    2000-01-01

    Full text: The use of independent collimators in the abutment of two adjacent treatment volumes, as in head and neck radiation treatments, consists typically of positioning the collimator rotation axis (CRA) at the junction of the volumes, and offsetting each field by its half-field width. This has the effect of positioning one of the collimator jaws at the CRA for each field. However, misalignment of the jaws can lead to variations in dose uniformity in the junction region. We have used gel dosimetry to measure junction doses in three dimensions. PAG gel MRI was used to investigate junction dosimetry for a mono-isocentriic treatment of two orthogonal pairs of opposed (ant/post and lateral) 6 MV x-ray beams. PAG gels in an 11cm diameter cylindrical gel phantom were imaged using a Siemens Vision 1.5 T MRI. The exposures were made using a Philips SL 20 linear accelerator with independent jaws that were known to overlap at the isocentre for sequential abutting offset (within manufacturer's specifications for symmetric fields). X-Omat V films were exposed in mono-directional beams, and optically scanned for comparison. Measurements of off-axis ratios and of relative depth profiles using gel MRI and perpendicular film were in excellent agreement with each other. Measurements through the multi-directional junction at the isocentre are illustrated in the graph, for orthogonal planes centred at the isocentre of the neck phantom. They demonstrate a minimum dose of 75 % of that of the adjacent 'treatment' regions, which agrees closely with the results measured (72%) in the mono-directional case with film. We conclude that this measurement confirms that junction dosimetry at the isocentre measured with perpendicular film for a single direction is a good approximation to the situation in multiple directions. Copyright (2000) Australasian College of Physical Scientists and Engineers in Medicine

  15. Charcoal disrupts cell-cell communication through multiple mechanisms

    Science.gov (United States)

    Gao, X.; Cheng, H. Y.; Liu, S.; Masiello, C. A.; Silberg, J. J.; Del Valle, I.

    2016-12-01

    Microbial cell-cell communication through the release and detection of small signaling molecules is employed by soil microbes to manage many biogeochemically relevant processes including production of biofilms, priming effects on native SOM, and management of methanogenesis and denitrification. Charcoal is a ubiquitous component of soil, entering soil either from natural fire or intentionally amended as biochar. Charcoal's presence in soil introduces spatial and temporal heterogeneity in nutrients and habitats for soil microbes and may trigger a range of biological effects not yet predictable, in part because it interferes with microbial cell-cell communication. We hypothesized that charcoal's alkalinity and large active surface area could affect the lifetime of some chemical compounds that microbes use for cell-cell signaling on times scales relevant to growth and communication. To test this idea, we examined the extent and rate of charcoal quenching of cell-cell communication caused by ten charcoals with a wide range of physicochemical properties. Our measurements focused on signaling mediated by an acyl-homoserine lactone (AHL), N-3-oxo-dodecanoyl-L-homoserine lactone, which is used by many gram-negative bacteria for quorum sensing. Our results from a bioassay and chemical sorption experiments revealed that charcoal can decrease the bioavailable level of AHL through a combination of sorption and pH-dependent hydrolysis of the lactone ring. We found that the kinetics of hydrolysis can exceed those of sorption. These findings implicate charcoal surface area and alkalinity as properties that could be tuned to regulate the degradation rates of cell-cell signaling molecules in soils. We then built a quantitative model that predicts the half-lives of different microbial signaling compounds in the presence of charcoals varying in pH and surface area. Our model results suggest that the effects of charcoal on pH-sensitive bacterial AHL signals will be fundamentally

  16. Coherent quantum transport in hybrid Nb-InGaAs-Nb Josephson junctions

    Science.gov (United States)

    Delfanazari, Kaveh; Puddy, R.; Ma, P.; Cao, M.; Yi, T.; Gul, Y.; Farrer, I.; Ritchie, D.; Joyce, H.; Kelly, M.; Smith, C.

    Because of the recently reported detection of Majorana fermions states at the superconductor-semiconductor (S-Sm) interface in InAs nanowire devices, the study of hybrid structures has received renewed interest. In this paper we present experimental results on proximity induced superconductivity in a high-mobility two-dimensional electron gas in InGaAs heterostructures. Eight symmetric S-Sm-S Josephson junctions were fabricated on a single InGaAs chip and each junction was measured individually using a lock-in measurement technique. The superconducting electrodes were made of Niobium (Nb). The measurements were carried out in a dilution fridge with a base temperature of 40 mK, and the quantum transport of junctions were measured below 800 mK. Owing to Andreev reflections at the S-Sm interfaces, the differential resistance (dV/dI) versus V curve shows the well-known subharmonic energy gap structure (SGS) at V = 2ΔNb/ne. The SGS features suppressed significantly with increasing temperature and magnetic field, leading to a shift of the SGSs toward zero bias. Our result paves the way for development of highly transparent hybrid S-Sm-S junctions and coherent circuits for quantum devices capable of performing quantum logic and processing functions.

  17. Real-time sensing of epithelial cell-cell and cell-substrate interactions by impedance spectroscopy on porous substrates

    International Nuclear Information System (INIS)

    Mondal, D.; RoyChaudhuri, C.; Pal, D.

    2015-01-01

    Oxidized porous silicon (PS) is a common topographical biocompatible substrate that potentially provides a distinct in vitro environment for better understanding of in vivo behavior. But in the reported studies on oxidized PS, cell-cell and cell-substrate interactions have been detected only by fluorescent labeling. This paper is the first attempt to investigate real-time sensing of these interactions on HaCaT cells by label-free impedance spectroscopy on oxidized PS of two pore diameters (50 and 500 nm). One of the major requirements for successful impedance spectroscopy measurement is to restrict the channeling of electric field lines through the pores. To satisfy this criterion, we have designed the pore depths after analyzing the penetration of the medium by using computational fluid dynamics simulation. A distributed electrical model was also developed for estimating the various cellular attributes by considering a pseudorandom distribution of pores. It is observed from the impedance measurements and from the model that the proliferation rate increases for 50 nm pores but decreases for 500 nm pores compared to that for planar substrates. The rate of decrease in cell substrate separation (h) in the initial stage is more than the rate of increase in cell-cell junction resistance (R b ) corresponding to the initial adhesion phase of cells. It is observed that R b and h are higher for 50 nm pores than those for planar substrates, corresponding to the fact that substrates more conducive toward cell adhesion encourage cell-cell interactions than direct cell-substrate interactions. Thus, the impedance spectroscopy coupled with the proposed theoretical framework for PS substrates can sense and quantify the cellular interactions

  18. Symmetric Euler orientation representations for orientational averaging.

    Science.gov (United States)

    Mayerhöfer, Thomas G

    2005-09-01

    A new kind of orientation representation called symmetric Euler orientation representation (SEOR) is presented. It is based on a combination of the conventional Euler orientation representations (Euler angles) and Hamilton's quaternions. The properties of the SEORs concerning orientational averaging are explored and compared to those of averaging schemes that are based on conventional Euler orientation representations. To that aim, the reflectance of a hypothetical polycrystalline material with orthorhombic crystal symmetry was calculated. The calculation was carried out according to the average refractive index theory (ARIT [T.G. Mayerhöfer, Appl. Spectrosc. 56 (2002) 1194]). It is shown that the use of averaging schemes based on conventional Euler orientation representations leads to a dependence of the result from the specific Euler orientation representation that was utilized and from the initial position of the crystal. The latter problem can be overcome partly by the introduction of a weighing factor, but only for two-axes-type Euler orientation representations. In case of a numerical evaluation of the average, a residual difference remains also if a two-axes type Euler orientation representation is used despite of the utilization of a weighing factor. In contrast, this problem does not occur if a symmetric Euler orientation representation is used as a matter of principle, while the result of the averaging for both types of orientation representations converges with increasing number of orientations considered in the numerical evaluation. Additionally, the use of a weighing factor and/or non-equally spaced steps in the numerical evaluation of the average is not necessary. The symmetrical Euler orientation representations are therefore ideally suited for the use in orientational averaging procedures.

  19. Population dynamics with symmetric and asymmetric harvesting

    Directory of Open Access Journals (Sweden)

    J. Ali

    2009-10-01

    Here $\\lambda, a, b, c$ and $L$ are positive constants with $0symmetric harvesting case and model B to an asymmetric harvesting case. Our objective is to study the existence of positive solutions and also discuss the effects of harvesting. We will develop appropriate quadrature methods via which we will establish our results.

  20. How Symmetrical Assumptions Advance Strategic Management Research

    DEFF Research Database (Denmark)

    Foss, Nicolai Juul; Hallberg, Hallberg

    2014-01-01

    We develop the case for symmetrical assumptions in strategic management theory. Assumptional symmetry obtains when assumptions made about certain actors and their interactions in one of the application domains of a theory are also made about this set of actors and their interactions in other...... application domains of the theory. We argue that assumptional symmetry leads to theoretical advancement by promoting the development of theory with greater falsifiability and stronger ontological grounding. Thus, strategic management theory may be advanced by systematically searching for asymmetrical...

  1. Symmetric Logic Synthesis with Phase Assignment

    OpenAIRE

    Benschop, N. F.

    2001-01-01

    Decomposition of any Boolean Function BF_n of n binary inputs into an optimal inverter coupled network of Symmetric Boolean functions SF_k (k \\leq n) is described. Each SF component is implemented by Threshold Logic Cells, forming a complete and compact T-Cell Library. Optimal phase assignment of input polarities maximizes local symmetries. The "rank spectrum" is a new BF_n description independent of input ordering, obtained by mapping its minterms onto an othogonal n \\times n grid of (transi...

  2. Entanglement of bosonic modes in symmetric graphs

    International Nuclear Information System (INIS)

    Asoudeh, M.; Karimipour, V.

    2005-01-01

    The ground and thermal states of a quadratic Hamiltonian representing the interaction of bosonic modes or particles are always Gaussian states. We investigate the entanglement properties of these states for the case where the interactions are represented by harmonic forces acting along the edges of symmetric graphs - i.e., one-, two-, and three-dimensional rectangular lattices, mean-field clusters, and platonic solids. We determine the entanglement of formation (EOF) as a function of the interaction strength, calculate the maximum EOF in each case, and compare these values with the bounds found previously for quadratic Hamiltonians

  3. Symmetric Circular Matchings and RNA Folding

    DEFF Research Database (Denmark)

    Hofacker, Ivo L.; Reidys, Christian; Stadler, Peter F.

    2012-01-01

    or the co-folding of two or more identical RNAs. Here, we show that the RNA folding problem with symmetry terms can still be solved with polynomial-time algorithms. Empirically, the fraction of symmetric ground state structures decreases with chain length, so that the error introduced by neglecting......RNA secondary structures can be computed as optimal solutions of certain circular matching problems. An accurate treatment of this energy minimization problem has to account for the small --- but non-negligible --- entropic destabilization of secondary structures with non-trivial automorphisms...

  4. Baryon symmetric big-bang cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Stecker, F.W.

    1978-04-01

    The framework of baryon-symmetric big-bang cosmology offers the greatest potential for deducing the evolution of the universe as a consequence of physical laws and processes with the minimum number of arbitrary assumptions as to initial conditions in the big-bang. In addition, it offers the possibility of explaining the photon-baryon ratio in the universe and how galaxies and galaxy clusters are formed, and also provides the only acceptable explanation at present for the origin of the cosmic gamma ray background radiation.

  5. Baryon symmetric big-bang cosmology

    International Nuclear Information System (INIS)

    Stecker, F.W.

    1978-04-01

    The framework of baryon-symmetric big-bang cosmology offers the greatest potential for deducing the evolution of the universe as a consequence of physical laws and processes with the minimum number of arbitrary assumptions as to initial conditions in the big-bang. In addition, it offers the possibility of explaining the photon-baryon ratio in the universe and how galaxies and galaxy clusters are formed, and also provides the only acceptable explanation at present for the origin of the cosmic gamma ray background radiation

  6. EWPD Constraints on Flavor Symmetric Vector Fields

    CERN Document Server

    Grinstein, Benjamín; Trott, Michael

    2011-01-01

    Electroweak precision data constraints on flavor symmetric vector fields are determined. The flavor multiplets of spin one that we examine are the complete set of fields that couple to quark bi-linears at tree level while not initially breaking the quark global flavor symmetry group. Flavor safe vector masses proximate to, and in some cases below, the electroweak symmetry breaking scale are found to be allowed. Many of these fields provide a flavor safe mechanism to explain the t tbar forward backward anomaly, and can simultaneously significantly raise the allowed values of the Standard Model Higgs mass consistent with electroweak precision data.

  7. 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.

  8. [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.

  9. Complexity Reduction Explains Preference to Symmetric Patterns

    Directory of Open Access Journals (Sweden)

    Jo-Hsuan Wu

    2011-05-01

    Full Text Available Symmetric patterns are more appealing to human observers than asymmetric ones. Here, we investigated the possible mechanisms underlying such preference. All Stimuli were derived from phase scrambled versions of forty face or nature images. There were four types of test images: symmetry, in which one part of the image was the reflective transform of the other part about an axis; repetition, one part of the image was a copy of the other part; anti-symmetry, similar to symmetry but the contrast of one side was reversed; and interleaved patterns, half of the symmetric pattern was replaced by a scrambled image. The number of axes ranged from 1 to 16 for all image types. The task of our 20 observers was to give a preference rating to each image on a 6-point Lickert Scale. The preference rating increased with the number of axis for all stimulus type. The preference to symmetry was similar to that to repetition and was slightly better than anti-symmetry. The preference to interleaved pattern was much less than other types of stimuli. The preference rating of an image has little correlation with the slope of the power spectrum but of the image but is inversely correlated with its complexity.

  10. Symmetric solutions of evolutionary partial differential equations

    Science.gov (United States)

    Bruell, Gabriele; Ehrnström, Mats; Geyer, Anna; Pei, Long

    2017-10-01

    We show that for a large class of evolutionary nonlinear and nonlocal partial differential equations, symmetry of solutions implies very restrictive properties of the solutions and symmetry axes. These restrictions are formulated in terms of three principles, based on the structure of the equations. The first principle covers equations that allow for steady solutions and shows that any spatially symmetric solution is in fact steady with a speed determined by the motion of the axis of symmetry at the initial time. The second principle includes equations that admit breathers and steady waves, and therefore is less strong: it holds that the axes of symmetry are constant in time. The last principle is a mixed case, when the equation contains terms of the kind from both earlier principles, and there may be different outcomes; for a class of such equations one obtains that a spatially symmetric solution must be constant in both time and space. We list and give examples of more than 30 well-known equations and systems in one and several dimensions satisfying these principles; corresponding results for weak formulations of these equations may be attained using the same techniques. Our investigation is a generalisation of a local and one-dimensional version of the first principle from Ehrnström et al (2009 Int. Math. Res. Not. 2009 4578-96) to nonlocal equations, systems and higher dimensions, as well as a study of the standing and mixed cases.

  11. Electroweak Baryogenesis in R-symmetric Supersymmetry

    Energy Technology Data Exchange (ETDEWEB)

    Fok, R.; Kribs, Graham D.; Martin, Adam; Tsai, Yuhsin

    2013-03-01

    We demonstrate that electroweak baryogenesis can occur in a supersymmetric model with an exact R-symmetry. The minimal R-symmetric supersymmetric model contains chiral superfields in the adjoint representation, giving Dirac gaugino masses, and an additional set of "R-partner" Higgs superfields, giving R-symmetric \\mu-terms. New superpotential couplings between the adjoints and the Higgs fields can simultaneously increase the strength of the electroweak phase transition and provide additional tree-level contributions to the lightest Higgs mass. Notably, no light stop is present in this framework, and in fact, we require both stops to be above a few TeV to provide sufficient radiative corrections to the lightest Higgs mass to bring it up to 125 GeV. Large CP-violating phases in the gaugino/higgsino sector allow us to match the baryon asymmetry of the Universe with no constraints from electric dipole moments due to R-symmetry. We briefly discuss some of the more interesting phenomenology, particularly of the of the lightest CP-odd scalar.

  12. 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.

  13. Nonlinear gap junctions enable long-distance propagation of pulsating calcium waves in astrocyte networks.

    Directory of Open Access Journals (Sweden)

    Mati Goldberg

    Full Text Available A new paradigm has recently emerged in brain science whereby communications between glial cells and neuron-glia interactions should be considered together with neurons and their networks to understand higher brain functions. In particular, astrocytes, the main type of glial cells in the cortex, have been shown to communicate with neurons and with each other. They are thought to form a gap-junction-coupled syncytium supporting cell-cell communication via propagating Ca(2+ waves. An identified mode of propagation is based on cytoplasm-to-cytoplasm transport of inositol trisphosphate (IP(3 through gap junctions that locally trigger Ca(2+ pulses via IP(3-dependent Ca(2+-induced Ca(2+ release. It is, however, currently unknown whether this intracellular route is able to support the propagation of long-distance regenerative Ca(2+ waves or is restricted to short-distance signaling. Furthermore, the influence of the intracellular signaling dynamics on intercellular propagation remains to be understood. In this work, we propose a model of the gap-junctional route for intercellular Ca(2+ wave propagation in astrocytes. Our model yields two major predictions. First, we show that long-distance regenerative signaling requires nonlinear coupling in the gap junctions. Second, we show that even with nonlinear gap junctions, long-distance regenerative signaling is favored when the internal Ca(2+ dynamics implements frequency modulation-encoding oscillations with pulsating dynamics, while amplitude modulation-encoding dynamics tends to restrict the propagation range. As a result, spatially heterogeneous molecular properties and/or weak couplings are shown to give rise to rich spatiotemporal dynamics that support complex propagation behaviors. These results shed new light on the mechanisms implicated in the propagation of Ca(2+ waves across astrocytes and the precise conditions under which glial cells may participate in information processing in the brain.

  14. 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...

  15. 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

  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. 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

  18. 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.

  19. 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.

  20. 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....

  1. Regulation and involvement in cancer and pathological conditions of MAGI1, a tight junction protein.

    Science.gov (United States)

    Feng, Xuemin; Jia, Shuqin; Martin, Tracey A; Jiang, Wen G

    2014-07-01

    Membrane-associated guanylate kinase with an inverted repeat member 1 (MAGI1), is a member of a family of proteins which are emerging as important in coupling the extracellular environment to intracellular signaling pathways and the cytoskeleton at synapses and tight junctions. Early studies described it as a scaffold protein localized at cell-cell junctions. Recently, MAGI1 was found to recruit various kinds of molecules via its PSD-95/Disks Large/Zonula Occludins (PDZ) domains to strengthen the junctional complex. There is an increasing body of evidence showing its involvement in receptor synaptic localization and the homeostasis of ion channels in the nervous system. Furthermore, evidence has accumulated to confirm the critical role of MAGI1 in regulating cell-cell contacts, which is always disrupted in tumor progression and is associated with invasiveness and metastasis. It has also been shown in vitro that the abnormal expression of MAGI1 influences the adhesion and invasiveness of cancer cells. Due to the presence of docking domains for PDZ-binding molecules, MAGI1 associates with a variety of molecules such as phosphatase and tensin homolog deleted on chromosome ten (PTEN), brain-specific angiogenesis inhibitor-1, β-catenin and the mouse homologue of the human NET1 DH domain protein. Pathway signaling analysis has indicated that MAGI1 is probably involved in many kinds of pathways especially the PTEN/Phosphatidylinositol-3 kinase/Akt pathway and the (Wg-Int)-β-catenin pathway which mediates intracellular functions. MAGI1 may therefore be a tumor suppressor and a therapy target for cancer and other diseases, although more in vitro and in vivo investigations are required. Copyright© 2014 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

  2. Singular symmetric functionals and Banach limits with additional invariance properties

    International Nuclear Information System (INIS)

    Dodds, P G; Pagter, B de; Sedaev, A A; Semenov, E M; Sukochev, F A

    2003-01-01

    For symmetric spaces of measurable functions on the real half-line, we study the problem of existence of positive linear functionals monotone with respect to the Hardy-Littlewood semi-ordering, the so-called symmetric functionals. Two new wide classes of symmetric spaces are constructed which are distinct from Marcinkiewicz spaces and for which the set of symmetric functionals is non-empty. We consider a new construction of singular symmetric functionals based on the translation-invariance of Banach limits defined on the space of bounded sequences. We prove the existence of Banach limits invariant under the action of the Hardy operator and all dilation operators. This result is used to establish the stability of the new construction of singular symmetric functionals for an important class of generating sequences

  3. Programming microbial population dynamics by engineered cell-cell communication.

    Science.gov (United States)

    Song, Hao; Payne, Stephen; Tan, Cheemeng; You, Lingchong

    2011-07-01

    A major aim of synthetic biology is to program novel cellular behavior using engineered gene circuits. Early endeavors focused on building simple circuits that fulfill simple functions, such as logic gates, bistable toggle switches, and oscillators. These gene circuits have primarily focused on single-cell behaviors since they operate intracellularly. Thus, they are often susceptible to cell-cell variations due to stochastic gene expression. Cell-cell communication offers an efficient strategy to coordinate cellular behavior at the population level. To this end, we review recent advances in engineering cell-cell communication to achieve reliable population dynamics, spanning from communication within single species to multispecies, from one-way sender-receiver communication to two-way communication in synthetic microbial ecosystems. These engineered systems serve as well-defined model systems to better understand design principles of their naturally occurring counterparts and to facilitate novel biotechnology applications. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Engineered cell-cell communication via DNA messaging

    Directory of Open Access Journals (Sweden)

    Ortiz Monica E

    2012-09-01

    Full Text Available Abstract Background Evolution has selected for organisms that benefit from genetically encoded cell-cell communication. Engineers have begun to repurpose elements of natural communication systems to realize programmed pattern formation and coordinate other population-level behaviors. However, existing engineered systems rely on system-specific small molecules to send molecular messages among cells. Thus, the information transmission capacity of current engineered biological communication systems is physically limited by specific biomolecules that are capable of sending only a single message, typically “regulate transcription.” Results We have engineered a cell-cell communication platform using bacteriophage M13 gene products to autonomously package and deliver heterologous DNA messages of varying lengths and encoded functions. We demonstrate the decoupling of messages from a common communication channel via the autonomous transmission of various arbitrary genetic messages. Further, we increase the range of engineered DNA messaging across semisolid media by linking message transmission or receipt to active cellular chemotaxis. Conclusions We demonstrate decoupling of a communication channel from message transmission within engineered biological systems via the autonomous targeted transduction of user-specified heterologous DNA messages. We also demonstrate that bacteriophage M13 particle production and message transduction occurs among chemotactic bacteria. We use chemotaxis to improve the range of DNA messaging, increasing both transmission distance and communication bit rates relative to existing small molecule-based communication systems. We postulate that integration of different engineered cell-cell communication platforms will allow for more complex spatial programming of dynamic cellular consortia.

  5. The role of tight junctions in mammary gland function.

    Science.gov (United States)

    Stelwagen, Kerst; Singh, Kuljeet

    2014-03-01

    Tight junctions (TJ) are cellular structures that facilitate cell-cell communication and are important in maintaining the three-dimensional structure of epithelia. It is only during the last two decades that the molecular make-up of TJ is becoming unravelled, with two major transmembrane-spanning structural protein families, called occludin and claudins, being the true constituents of the TJ. These TJ proteins are linked via specific scaffolding proteins to the cell's cytoskeleton. In the mammary gland TJ between adjacent secretory epithelial cells are formed during lactogenesis and are instrumental in establishing and maintaining milk synthesis and secretion, whereas TJ integrity is compromised during mammary involution and also as result of mastitis and periods of mammary inflamation (including mastitis). They prevent the paracellular transport of ions and small molecules between the blood and milk compartments. Formation of intact TJ at the start of lactation is important for the establishment of the lactation. Conversely, loss of TJ integrity has been linked to reduced milk secretion and mammary function and increased paracellular transport of blood components into the milk and vice versa. In addition to acting as a paracellular barrier, the TJ is increasingly linked to playing an active role in intracellular signalling. This review focusses on the role of TJ in mammary function of the normal, non-malignant mammary gland, predominantly in ruminants, the major dairy producing species.

  6. 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

  7. Symmetric Markov Processes, Time Change, and Boundary Theory (LMS-35)

    CERN Document Server

    Chen, Zhen-Qing

    2011-01-01

    This book gives a comprehensive and self-contained introduction to the theory of symmetric Markov processes and symmetric quasi-regular Dirichlet forms. In a detailed and accessible manner, Zhen-Qing Chen and Masatoshi Fukushima cover the essential elements and applications of the theory of symmetric Markov processes, including recurrence/transience criteria, probabilistic potential theory, additive functional theory, and time change theory. The authors develop the theory in a general framework of symmetric quasi-regular Dirichlet forms in a unified manner with that of regular Dirichlet forms

  8. On The K-Pseudo Symmetric and Ordinary Differentiation

    OpenAIRE

    Łazarow E.; Turowska M.

    2016-01-01

    In 1972, S. Valenti introduced the definition of k-pseudo symmetric derivative and has shown that the set of all points of a continuous function, at which there exists a finite k-pseudo symmetric derivative but the finite ordinary derivative does not exist, is of Lebesgue measure zero. In 1993, L. Zajícek has shown that for a continuous function f, the set of all points, at which f is symmetrically differentiable but no differentiable, is σ-(1 - ε) symmetrically porous for every ε > 0. The qu...

  9. Numerical investigation on splitting of ferrofluid microdroplets in T-junctions using an asymmetric magnetic field with proposed correlation

    Science.gov (United States)

    Aboutalebi, Mohammad; Bijarchi, Mohamad Ali; Shafii, Mohammad Behshad; Kazemzadeh Hannani, Siamak

    2018-02-01

    The studies surrounding the concept of microdroplets have seen a dramatic increase in recent years. Microdroplets have applications in different fields such as chemical synthesis, biology, separation processes and micro-pumps. This study numerically investigates the effect of different parameters such as Capillary number, Length of droplets, and Magnetic Bond number on the splitting process of ferrofluid microdroplets in symmetric T-junctions using an asymmetric magnetic field. The use of said field that is applied asymmetrically to the T-junction center helps us control the splitting of ferrofluid microdroplets. During the process of numerical simulation, a magnetic field with various strengths from a dipole located at a constant distance from the center of the T-junction was applied. The main advantage of this design is its control over the splitting ratio of daughter droplets and reaching various microdroplet sizes in a T-junction by adjusting the magnetic field strength. The results showed that by increasing the strength of the magnetic field, the possibility of asymmetric splitting of microdroplets increases in a way that for high values of field strength, high splitting ratios can be reached. Also, by using the obtained results at various Magnetic Bond numbers and performing curve fitting, a correlation is derived that can be used to accurately predict the borderline between splitting and non-splitting zones of microdroplets flow in micro T-junctions.

  10. Polyhomogeneous expansions from time symmetric initial data

    Science.gov (United States)

    Gasperín, E.; Valiente Kroon, J. A.

    2017-10-01

    We make use of Friedrich’s construction of the cylinder at spatial infinity to relate the logarithmic terms appearing in asymptotic expansions of components of the Weyl tensor to the freely specifiable parts of time symmetric initial data sets for the Einstein field equations. Our analysis is based on the assumption that a particular type of formal expansions near the cylinder at spatial infinity corresponds to the leading terms of actual solutions to the Einstein field equations. In particular, we show that if the Bach tensor of the initial conformal metric does not vanish at the point at infinity then the most singular component of the Weyl tensor decays near null infinity as O(\\tilde{r}-3\\ln \\tilde{r}) so that spacetime will not peel. We also provide necessary conditions on the initial data which should lead to a peeling spacetime. Finally, we show how to construct global spacetimes which are candidates for non-peeling (polyhomogeneous) asymptotics.

  11. Symmetric Functional Model for Extensions of Hermitian

    CERN Document Server

    Ryzhov, V

    2006-01-01

    This paper offers the functional model of a class of non-selfadjoint extensions of a Hermitian operator with equal deficiency indices. The explicit form of dilation of a dissipative extension is offered and the symmetric form of Sz.Nagy-Foia\\c{s} model as developed by B.~Pavlov is constructed. A variant of functional model for a general non-selfadjoint non-dissipative extension is formulated. We illustrate the theory by two examples: singular perturbations of the Laplace operator in~$L_2(\\Real^3)$ by a finite number of point interactions, and the Schr\\"odinger operator on the half axis~$(0, \\infty)$ in the Weyl limit circle case at infinity.

  12. BFV quantization on hermitian symmetric spaces

    International Nuclear Information System (INIS)

    Fradkin, E.S.; Linetsky, V.Ya.

    1994-12-01

    Gauge-invariant BFV approach to geometric quantization is applied to the case of hermitian symmetric spaces G/H. In particular, gauge invariant quantization on the Lobachevsky plane and sphere is carried out. Due to the presence of symmetry, master equations for the first-class constraints, quantum observables and physical quantum states are exactly solvable. BFV-BRST operator defines a flat G-connection in the Fock bundle over G/H. Physical states are covariantly constant sections with respect to this connection and are shown to coincide with the generalized coherent states for the group G. Vacuum expectation values of the quantum observables commuting with the quantum first-class constraints reduce to the covariant symbols of Berezin. The gauge-invariant approach to quantization on symplectic manifolds synthesizes geometric, deformation and Berezin quantization approaches. (author). 28 refs

  13. From Symmetric Glycerol Derivatives to Dissymmetric Chlorohydrins

    Directory of Open Access Journals (Sweden)

    Gemma Villorbina

    2011-03-01

    Full Text Available The anticipated worldwide increase in biodiesel production will result in an accumulation of glycerol for which there are insufficient conventional uses. The surplus of this by-product has increased rapidly during the last decade, prompting a search for new glycerol applications. We describe here the synthesis of dissymmetric chlorohydrin esters from symmetric 1,3-dichloro-2-propyl esters obtained from glycerol. We studied the influence of two solvents: 1,4-dioxane and 1-butanol and two bases: sodium carbonate and 1-butylimidazole, on the synthesis of dissymmetric chlorohydrin esters. In addition, we studied the influence of other bases (potassium and lithium carbonates in the reaction using 1,4-dioxane as the solvent. The highest yield was obtained using 1,4-dioxane and sodium carbonate.

  14. Left-right symmetric electroweak models

    International Nuclear Information System (INIS)

    Olness, F.I.

    1989-10-01

    We present a critical analysis of the spontaneous symmetry breaking and the Higgs sector of the conventional SU(2) L circle-times SU(2) R circle-times U(1) B-L left-right symmetric theory involving bi-doublet and triplet Higgs fields. We examine the phenomenological constraints imposed on the minimization of the Higgs potential arising from experimental observations, and explore the resulting consequences including the problem of ''fine- tuning'' arising from the hierarchy of mass scales involved. We show that it is non-trivial to satisfy all of these constraints. We contrast the benefits of this general class left-right models against the required ''fine-tuning'' necessary to force the phenomenology to conform to experimental fact. 17 refs., 1 fig

  15. Geometric inequalities for axially symmetric black holes

    International Nuclear Information System (INIS)

    Dain, Sergio

    2012-01-01

    A geometric inequality in general relativity relates quantities that have both a physical interpretation and a geometrical definition. It is well known that the parameters that characterize the Kerr-Newman black hole satisfy several important geometric inequalities. Remarkably enough, some of these inequalities also hold for dynamical black holes. This kind of inequalities play an important role in the characterization of the gravitational collapse; they are closely related with the cosmic censorship conjecture. Axially symmetric black holes are the natural candidates to study these inequalities because the quasi-local angular momentum is well defined for them. We review recent results in this subject and we also describe the main ideas behind the proofs. Finally, a list of relevant open problems is presented. (topical review)

  16. Minimal Left-Right Symmetric Dark Matter.

    Science.gov (United States)

    Heeck, Julian; Patra, Sudhanwa

    2015-09-18

    We show that left-right symmetric models can easily accommodate stable TeV-scale dark matter particles without the need for an ad hoc stabilizing symmetry. The stability of a newly introduced multiplet either arises accidentally as in the minimal dark matter framework or comes courtesy of the remaining unbroken Z_{2} subgroup of B-L. Only one new parameter is introduced: the mass of the new multiplet. As minimal examples, we study left-right fermion triplets and quintuplets and show that they can form viable two-component dark matter. This approach is, in particular, valid for SU(2)×SU(2)×U(1) models that explain the recent diboson excess at ATLAS in terms of a new charged gauge boson of mass 2 TeV.

  17. Primordial two-component maximally symmetric inflation

    Science.gov (United States)

    Enqvist, K.; Nanopoulos, D. V.; Quirós, M.; Kounnas, C.

    1985-12-01

    We propose a two-component inflation model, based on maximally symmetric supergravity, where the scales of reheating and the inflation potential at the origin are decoupled. This is possible because of the second-order phase transition from SU(5) to SU(3)×SU(2)×U(1) that takes place when φ≅φcinflation at the global minimum, and leads to a reheating temperature TR≅(1015-1016) GeV. This makes it possible to generate baryon asymmetry in the conventional way without any conflict with experimental data on proton lifetime. The mass of the gravitinos is m3/2≅1012 GeV, thus avoiding the gravitino problem. Monopoles are diluted by residual inflation in the broken phase below the cosmological bounds if φcUSA.

  18. Cosmic ray antimatter and baryon symmetric cosmology

    Science.gov (United States)

    Stecker, F. W.; Protheroe, R. J.; Kazanas, D.

    1982-01-01

    The relative merits and difficulties of the primary and secondary origin hypotheses for the observed cosmic-ray antiprotons, including the new low-energy measurement of Buffington, et al. We conclude that the cosmic-ray antiproton data may be evidence for antimatter galaxies and baryon symmetric cosmology. The present bar P data are consistent with a primary extragalactic component having /p=/equiv 1+/- 3.2/0.7x10 = to the -4 independent of energy. We propose that the primary extragalactic cosmic ray antiprotons are most likely from active galaxies and that expected disintegration of bar alpha/alpha ban alpha/alpha. We further predict a value for ban alpha/alpha =/equiv 10 to the -5, within range of future cosmic ray detectors.

  19. Design and Analysis of Symmetric Primitives

    DEFF Research Database (Denmark)

    Lauridsen, Martin Mehl

    parts of the input to obtain dependency between the state bits. With this operation in focus, we give a range of theoretical results, reducing the possible choices for the operation in generalized ciphers to a particular set of classes. We then employ a computer-aided optimization technique to determine...... for the ongoing CAESAR competition for authenticated encryption with associated data. We describe the design criteria, the usage modes and give proofs of security. Finally, in the third part, we consider implementation aspects of symmetric cryptography, with focus on high-performance software. In more detail, we...... analyze and implement modes recommended by the National Institute of Standards and Technology (NIST), as well as authenticated encryption modes from the CAESAR competition, when instantiated with the AES. The data processed in our benchmarking has sizes representative to that of typical Internet traffic...

  20. FFLP problem with symmetric trapezoidal fuzzy numbers

    Directory of Open Access Journals (Sweden)

    Reza Daneshrad

    2015-04-01

    Full Text Available The most popular approach for solving fully fuzzy linear programming (FFLP problems is to convert them into the corresponding deterministic linear programs. Khan et al. (2013 [Khan, I. U., Ahmad, T., & Maan, N. (2013. A simplified novel technique for solving fully fuzzy linear programming problems. Journal of Optimization Theory and Applications, 159(2, 536-546.] claimed that there had been no method in the literature to find the fuzzy optimal solution of a FFLP problem without converting it into crisp linear programming problem, and proposed a technique for the same. Others showed that the fuzzy arithmetic operation used by Khan et al. (2013 had some problems in subtraction and division operations, which could lead to misleading results. Recently, Ezzati et al. (2014 [Ezzati, R., Khorram, E., & Enayati, R. (2014. A particular simplex algorithm to solve fuzzy lexicographic multi-objective linear programming problems and their sensitivity analysis on the priority of the fuzzy objective functions. Journal of Intelligent and Fuzzy Systems, 26(5, 2333-2358.] defined a new operation on symmetric trapezoidal fuzzy numbers and proposed a new algorithm to find directly a lexicographic/preemptive fuzzy optimal solution of a fuzzy lexicographic multi-objective linear programming problem by using new fuzzy arithmetic operations, but their model was not fully fuzzy optimization. In this paper, a new method, by using Ezzati et al. (2014’s fuzzy arithmetic operation and a fuzzy version of simplex algorithm, is proposed for solving FFLP problem whose parameters are represented by symmetric trapezoidal fuzzy number without converting the given problem into crisp equivalent problem. By using the proposed method, the fuzzy optimal solution of FFLP problem can be easily obtained. A numerical example is provided to illustrate the proposed method.

  1. Symmetric Topological Phases and Tensor Network States

    Science.gov (United States)

    Jiang, Shenghan

    Classification and simulation of quantum phases are one of main themes in condensed matter physics. Quantum phases can be distinguished by their symmetrical and topological properties. The interplay between symmetry and topology in condensed matter physics often leads to exotic quantum phases and rich phase diagrams. Famous examples include quantum Hall phases, spin liquids and topological insulators. In this thesis, I present our works toward a more systematically understanding of symmetric topological quantum phases in bosonic systems. In the absence of global symmetries, gapped quantum phases are characterized by topological orders. Topological orders in 2+1D are well studied, while a systematically understanding of topological orders in 3+1D is still lacking. By studying a family of exact solvable models, we find at least some topological orders in 3+1D can be distinguished by braiding phases of loop excitations. In the presence of both global symmetries and topological orders, the interplay between them leads to new phases termed as symmetry enriched topological (SET) phases. We develop a framework to classify a large class of SET phases using tensor networks. For each tensor class, we can write down generic variational wavefunctions. We apply our method to study gapped spin liquids on the kagome lattice, which can be viewed as SET phases of on-site symmetries as well as lattice symmetries. In the absence of topological order, symmetry could protect different topological phases, which are often referred to as symmetry protected topological (SPT) phases. We present systematic constructions of tensor network wavefunctions for bosonic symmetry protected topological (SPT) phases respecting both onsite and spatial symmetries.

  2. 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.

  3. 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)

  4. 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)

  5. 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....

  6. 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...

  7. FACES WITH LARGE DIAMETER ON THE SYMMETRICAL TRAVELING SALESMAN POLYTOPE

    NARCIS (Netherlands)

    SIERKSMA, G; TIJSSEN, GA

    This paper deals with the symmetric traveling salesman polytope and contains three main theorems. The first one gives a new characterization of (non)adjacency. Based on this characterization a new upper bound for the diameter of the symmetric traveling salesman polytope (conjectured to be 2 by M.

  8. SUSY formalism for the symmetric double well potential

    Indian Academy of Sciences (India)

    symmetric double well potential barrier we have obtained a class of exactly solvable potentials subject to moving boundary condition. The eigenstates are also obtained by the same technique. Keywords. SUSY; moving boundary condition; exactly solvable; symmetric double well; NH3 molecule. PACS Nos 02.30.Ik; 03.50.

  9. Stability of transparent spherically symmetric thin shells and wormholes

    International Nuclear Information System (INIS)

    Ishak, Mustapha; Lake, Kayll

    2002-01-01

    The stability of transparent spherically symmetric thin shells (and wormholes) to linearized spherically symmetric perturbations about static equilibrium is examined. This work generalizes and systematizes previous studies and explores the consequences of including the cosmological constant. The approach shows how the existence (or not) of a domain wall dominates the landscape of possible equilibrium configurations

  10. Coupled dilaton and electromagnetic field in cylindrically symmetric ...

    Indian Academy of Sciences (India)

    Nature of circular geodesics is also studied in the presence of dilaton field in the cylindrically symmetric spacetime. Keywords. Dilaton field; general relativity; cylindrically symmetric spacetime. PACS Nos 04.50+h; .... For economy of space we skip all details of the intermediate steps and give the final expressions of the ...

  11. Synthesis & Characterization of New bis-Symmetrical Adipoyl ...

    African Journals Online (AJOL)

    Full Title: Synthesis and Characterization of New bis-Symmetrical Adipoyl, Terepthaloyl, Chiral Diimido-di-L-alanine Diesters and Chiral Phthaloyl-L-alanine Ester of Tripropoxy p-tert-Butyl Calix[4]arene and Study of Their Hosting Ability for Alanine and Na+. Bis-symmetrical tripropoxy p-tert-butyl calix[4]arene esters were ...

  12. Sparse symmetric preconditioners for dense linear systems in electromagnetism

    NARCIS (Netherlands)

    Carpentieri, Bruno; Duff, Iain S.; Giraud, Luc; Monga Made, M. Magolu

    2004-01-01

    We consider symmetric preconditioning strategies for the iterative solution of dense complex symmetric non-Hermitian systems arising in computational electromagnetics. In particular, we report on the numerical behaviour of the classical incomplete Cholesky factorization as well as some of its recent

  13. A nine-level hybrid symmetric cascaded multilevel converter for ...

    Indian Academy of Sciences (India)

    Indrajit Sarkar

    Abstract. A nine-level hybrid symmetric cascaded multilevel converter (MLC) fed induction motor drive is proposed in this paper. The proposed converter is capable of producing nine output voltage levels by using the same number of power cells as that of conventional five-level symmetric cascaded H-bridge converter.

  14. Radon transformation on reductive symmetric spaces: support theorems

    NARCIS (Netherlands)

    Kuit, J.J.|info:eu-repo/dai/nl/313872589

    2011-01-01

    In this thesis we introduce a class of Radon transforms for reductive symmetric spaces, including the horospherical transforms, and study some of their properties. In particular we obtain a generalization of Helgason's support theorem for the horospherical transform on a Riemannian symmetric space.

  15. A New Formulation for Symmetric Implicit Runge-Kutta-Nystrom ...

    African Journals Online (AJOL)

    In this paper we derive symmetric stable Implicit Runge-Kutta –Nystrom Method for the Integration of General Second Order ODEs by using the collocation approach.The block hybrid method obtained by the evaluation of the continuous interpolant at different nodes of the polynomial is symmetric and suitable for stiff intial ...

  16. New approach to solve symmetric fully fuzzy linear systems

    Indian Academy of Sciences (India)

    In this paper, we present a method to solve fully fuzzy linear systems with symmetric coefficient matrix. The symmetric coefficient matrix is decomposed into two systems of equations by using Cholesky method and then a solution can be obtained. Numerical examples are given to illustrate our method.

  17. A nine-level hybrid symmetric cascaded multilevel converter for ...

    Indian Academy of Sciences (India)

    A nine-level hybrid symmetric cascaded multilevel converter (MLC) fed induction motor drive is proposed in this paper. The proposed converter is capable of producing nine output voltage levels by using the same number of power cells as that of conventional five-level symmetric cascaded H-bridge converter. Eachphase in ...

  18. Matix hamiltonians with a chance of being complex symmetric

    Czech Academy of Sciences Publication Activity Database

    Znojil, Miloslav

    2012-01-01

    Roč. 74, č. 1 (2012), s. 5-6 ISSN 0378-620X Grant - others:European Science Foundation(CH) EW09-104 Institutional support: RVO:61389005 Keywords : PT-symmetric quantum mechanics * N-sited quantum chains * complex symmetric observables Subject RIV: BE - Theoretical Physics Impact factor: 0.713, year: 2012

  19. Classification of third-order symmetric Lorentzian manifolds

    OpenAIRE

    Galaev, Anton S.

    2014-01-01

    Third-order symmetric Lorentzian manifolds, i.e. Lorentzian manifold with zero third derivative of the curvature tensor, are classified. These manifolds are exhausted by a special type of pp-waves, they generalize Cahen-Wallach spaces and second-order symmetric Lorentzian spaces.

  20. Haemorrhagic snake venom metalloproteases and human ADAMs cleave LRP5/6, which disrupts cell-cell adhesions in vitro and induces haemorrhage in vivo.

    Science.gov (United States)

    Seo, Tadahiko; Sakon, Taketo; Nakazawa, Shiori; Nishioka, Asuka; Watanabe, Kohei; Matsumoto, Kaori; Akasaka, Mari; Shioi, Narumi; Sawada, Hitoshi; Araki, Satohiko

    2017-06-01

    Snake venom metalloproteases (SVMPs) are members of the a disintegrin and metalloprotease (ADAM) family of proteins, as they possess similar domains. SVMPs are known to elicit snake venom-induced haemorrhage; however, the target proteins and cleavage sites are not known. In this work, we identified a target protein of vascular apoptosis-inducing protein 1 (VAP1), an SVMP, relevant to its ability to induce haemorrhage. VAP1 disrupted cell-cell adhesions by relocating VE-cadherin and γ-catenin from the cell-cell junction to the cytosol, without inducing proteolysis of VE-cadherin. The Wnt receptors low-density lipoprotein receptor-related proteins 5 and 6 (LRP5/6) are known to promote catenin relocation, and are rendered constitutively active in Wnt signalling by truncation. Thus, we examined whether VAP1 cleaves LRP5/6 to induce catenin relocation. Indeed, we found that VAP1 cleaved the extracellular region of LRP6 and LRP5. This cleavage removes four inhibitory β-propeller structures, resulting in activation of LRP5/6. Recombinant human ADAM8 and ADAM12 also cleaved LRP6 at the same site. An antibody against a peptide including the LRP6-cleavage site inhibited VAP1-induced VE-cadherin relocation and disruption of cell-cell adhesions in cultured cells, and blocked haemorrhage in mice in vivo. Intriguingly, animals resistant to the effects of haemorrhagic snake venom express variants of LRP5/6 that lack the VAP1-cleavage site, or low-density lipoprotein receptor domain class A domains involved in formation of the constitutively active form. The results validate LRP5/6 as physiological targets of ADAMs. Furthermore, they indicate that SVMP-induced cleavage of LRP5/6 causes disruption of cell-cell adhesion and haemorrhage, potentially opening new avenues for the treatment of snake bites. © 2017 Federation of European Biochemical Societies.

  1. 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

  2. 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)

  3. 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)

  4. 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

  5. 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.)

  6. Computational Fluid Dynamics Analysis of Flexible Duct Junction Box Design

    Energy Technology Data Exchange (ETDEWEB)

    Beach, Robert [IBACOS Inc., Pittsburgh, PA (United States); Prahl, Duncan [IBACOS Inc., Pittsburgh, PA (United States); Lange, Rich [IBACOS Inc., Pittsburgh, PA (United States)

    2013-12-01

    IBACOS explored the relationships between pressure and physical configurations of flexible duct junction boxes by using computational fluid dynamics (CFD) simulations to predict individual box parameters and total system pressure, thereby ensuring improved HVAC performance. Current Air Conditioning Contractors of America (ACCA) guidance (Group 11, Appendix 3, ACCA Manual D, Rutkowski 2009) allows for unconstrained variation in the number of takeoffs, box sizes, and takeoff locations. The only variables currently used in selecting an equivalent length (EL) are velocity of air in the duct and friction rate, given the first takeoff is located at least twice its diameter away from the inlet. This condition does not account for other factors impacting pressure loss across these types of fittings. For each simulation, the IBACOS team converted pressure loss within a box to an EL to compare variation in ACCA Manual D guidance to the simulated variation. IBACOS chose cases to represent flows reasonably correlating to flows typically encountered in the field and analyzed differences in total pressure due to increases in number and location of takeoffs, box dimensions, and velocity of air, and whether an entrance fitting is included. The team also calculated additional balancing losses for all cases due to discrepancies between intended outlet flows and natural flow splits created by the fitting. In certain asymmetrical cases, the balancing losses were significantly higher than symmetrical cases where the natural splits were close to the targets. Thus, IBACOS has shown additional design constraints that can ensure better system performance.

  7. On The K-Pseudo Symmetric and Ordinary Differentiation

    Directory of Open Access Journals (Sweden)

    Łazarow E.

    2016-06-01

    Full Text Available In 1972, S. Valenti introduced the definition of k-pseudo symmetric derivative and has shown that the set of all points of a continuous function, at which there exists a finite k-pseudo symmetric derivative but the finite ordinary derivative does not exist, is of Lebesgue measure zero. In 1993, L. Zajícek has shown that for a continuous function f, the set of all points, at which f is symmetrically differentiable but no differentiable, is σ-(1 - ε symmetrically porous for every ε > 0. The question arises: can we transferred the Zajícek’s result to the case of the k-pseudo symmetric derivative?

  8. Structural basis of cell-cell adhesion by NCAM

    DEFF Research Database (Denmark)

    Kasper, C; Rasmussen, H; Kastrup, Jette Sandholm Jensen

    2000-01-01

    The neural cell adhesion molecule NCAM, a member of the immunoglobulin superfamily, mediates cell-cell recognition and adhesion via a homophilic interaction. NCAM plays a key role during development and regeneration of the nervous system and is involved in synaptic plasticity associated with memory...... and learning. The 1.85 A crystal structure of the two N-terminal extracellular domains of NCAM reported here provides a structural basis for the homophilic interaction. The molecular packing of the two-domain structure reveals a cross shaped antiparallel dimer, and provides fundamental insight into trans-cellular...

  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. 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

  12. 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.

  13. Prevention of cisplatin-induced ototoxicity by the inhibition of gap junctional intercellular communication in auditory cells.

    Science.gov (United States)

    Kim, Yeon Ju; Kim, Jangho; Tian, Chunjie; Lim, Hye Jin; Kim, Young Sun; Chung, Jong Hoon; Choung, Yun-Hoon

    2014-10-01

    Cis-diamminedichloroplatinum (cisplatin) is an effective chemotherapeutic drug for cancer therapy. However, most patients treated with cisplatin are at a high risk of ototoxicity, which causes severe hearing loss. Inspired by the "Good Samaritan effect" or "bystander effect" from gap junction coupling, we investigated the role of gap junctions in cisplatin-induced ototoxicity as a potential therapeutic method. We showed that connexin 43 (Cx43) was highly expressed in House Ear Institute-Organ of Corti 1 (HEI-OC1) cells, mediating cell-cell communication. The viability of HEI-OC1 cells was greatly decreased by cisplatin treatment, and cisplatin-treated HEI-OC1 cells showed lower Cx43 expression compared to that of untreated HEI-OC1 cells. In particular, high accumulation of Cx43 was observed around the nucleus of cisplatin-treated cells, whereas scattered punctuate expression of Cx43 was observed in the cytoplasm and membrane in normal cells, suggesting that cisplatin may interrupt the normal gap junction communication by inhibiting the trafficking of Cx43 to cell membranes in HEI-OC1 cells. Interestingly, we found that the inhibition of gap junction activity reduced cisplatin-induced apoptosis of auditory hair cells. Cx43 siRNA- or 18α-GA-treated HEI-OC1 cells showed higher cell viability compared to control HEI-OC1 cells during cisplatin treatment; this was also supported by fluorescence recovery after photobleaching studies. Inhibition of gap junction activity reduced recovery of calcein acetoxymethyl ester fluorescence compared to control cells. Additionally, analysis of the mechanisms involved demonstrated that highly activate extracellular signal-regulated kinase and protein kinase B, combined with inhibition of gap junctions may promote cell viability during cisplatin treatment.

  14. Temperature-Dependent Asymmetry of Anisotropic Magnetoresistance in Silicon p-n Junctions.

    Science.gov (United States)

    Yang, D Z; Wang, T; Sui, W B; Si, M S; Guo, D W; Shi, Z; Wang, F C; Xue, D S

    2015-09-01

    We report a large but asymmetric magnetoresistance in silicon p-n junctions, which contrasts with the fact of magnetoresistance being symmetric in magnetic metals and semiconductors. With temperature decreasing from 293 K to 100 K, the magnetoresistance sharply increases from 50% to 150% under a magnetic field of 2 T. At the same time, an asymmetric magnetoresistance, which manifests itself as a magnetoresistance voltage offset with respect to the sign of magnetic field, occurs and linearly increases with magnetoresistance. More interestingly, in contrast with other materials, the lineshape of anisotropic magnetoresistance in silicon p-n junctions significantly depends on temperature. As temperature decreases from 293 K to 100 K, the width of peak shrinks from 90° to 70°. We ascribe these novel magnetoresistance to the asymmetric geometry of the space charge region in p-n junction induced by the magnetic field. In the vicinity of the space charge region the current paths are deflected, contributing the Hall field to the asymmetric magnetoresistance. Therefore, the observed temperature-dependent asymmetry of magnetoresistance is proved to be a direct consequence of the spatial configuration evolution of space charge region with temperature.

  15. Engineering features of the Madison Symmetric Torus

    International Nuclear Information System (INIS)

    Dexter, R.N.; Kerst, D.W.; Lovell, T.W.; Prager, S.C.; Sprott, J.C.

    1987-01-01

    We describe the design parameters, unconventional features, and status of the Madison Symmetric Torus, MST, an RFP now approaching completion. A desire to minimize field errors dominated the design, leading to flanged gaps and inclusion of a pumping duct with small pump ports into the shell. No liner was to be used in the initial configuration, the versatile aluminum shell being the vacuum containment vessel (VCV). Simplified access to the inside of the vacuum vessel was accomplished by using the tank itself as single-turn poloidal as well as single-turn toroidal field coil. Thus none of the familiar toroidal or poloidal field coil sets surround the tank. A girder structure has been installed to permit removing the core-keeper and top-half of the vacuum vessel for insertion of internal shells or liners. More routinely, we intend to lift core-keeper and top half of the VCV together for entry of personnel into the VCV for changes of internal diagnostics or limiting surfaces, or for installation of movable limiters, etc. All structural features were designed to ease disassembly. 5 figs

  16. Experimental pseudo-symmetric trap EPSILON

    International Nuclear Information System (INIS)

    Skovoroda, A.A.; Arsenin, V.V.; Dlougach, E.D.; Kulygin, V.M.; Kuyanov, A.Yu.; Timofeev, A.V.; Zhil'tsov, V.A.; Zvonkov, A.V.

    2001-01-01

    Within the framework of the conceptual project 'Adaptive Plasma EXperiment' a trap with the closed magnetic field lines 'Experimental Pseudo-Symmetric trap' is examined. The project APEX is directed at the theoretical and experimental development of physical foundations for stationary thermonuclear reactor on the basis of an alternative magnetic trap with tokamak-level confinement of high β plasma. The fundamental principle of magnetic field pseudosymmetry that should be satisfied for plasma to have tokamak-like confinement is discussed. The calculated in paraxial approximation examples of pseudosymmetric curvilinear elements with poloidal direction of B isolines are adduced. The EPSILON trap consisting of two straight axisymmetric mirrors linked by two curvilinear pseudosymmetric elements is considered. The plasma currents are short-circuited within the curvilinear element what increases the equilibrium β. The untraditional scheme of MHD stabilization of a trap with the closed field lines by the use of divertor inserted into axisymmetric mirror is analyzed. The experimental installation EPSILON-OME that is under construction for experimental check of divertor stabilization is discussed. The possibility of ECR plasma production in EPSILON-OME under conditions of high density and small magnetic field is examined. (author)

  17. Device Simulation using Symmetric Smoothed Particle Hydrodynamics

    Science.gov (United States)

    Kitayama, K.; Toogoshi, M.; Zempo, Y.

    2017-10-01

    We have applied symmetric smoothed particle hydrodynamics (SSPH) to electronic structure calculations for high electron mobility transistors (HEMTs). In layered structures such as field effect transistors (FETs), and especially HEMTs, the current density is mainly dependent on the electron mobility and the electronic field near the gate, where both can be taken to be constant. The relation between the channel current and the applied gate voltage can be obtained by a one-dimensional calculation. Then, it is easy to apply SSPH to evaluate the simple quantum properties of a device. We mainly focus on the I-V characteristics, which are typical device features. The electronic structure of a HEMT was calculated using both SSPH and finite-difference (FD) methods. The results from SSPH calculations are in good agreement with those from the FD method, and the accuracy of SSPH is similar to that of FD. In a simple example, where three particles are employed in the SSPH domain, we show there is an equivalence to the three-point method in FD.

  18. Triple symmetric key cryptosystem for data security

    Science.gov (United States)

    Fuzail, C. Md; Norman, Jasmine; Mangayarkarasi, R.

    2017-11-01

    As the technology is getting spreads in the macro seconds of speed and in which the trend changing era from human to robotics the security issue is also getting increased. By means of using machine attacks it is very easy to break the cryptosystems in very less amount of time. Cryptosystem is a process which provides the security in all sorts of processes, communications and transactions to be done securely with the help of electronical mechanisms. Data is one such thing with the expanded implication and possible scraps over the collection of data to secure predominance and achievement, Information Security is the process where the information is protected from invalid and unverified accessibilities and data from mishandling. So the idea of Information Security has risen. Symmetric key which is also known as private key.Whereas the private key is mostly used to attain the confidentiality of data. It is a dynamic topic which can be implemented over different applications like android, wireless censor networks, etc. In this paper, a new mathematical manipulation algorithm along with Tea cryptosystem has been implemented and it can be used for the purpose of cryptography. The algorithm which we proposed is straightforward and more powerful and it will authenticate in harder way and also it will be very difficult to break by someone without knowing in depth about its internal mechanisms.

  19. Dynamic properties of symmetric optothermal microactuator

    Science.gov (United States)

    You, Q. Y.; Zhang, H. J.; Wang, Y. D.; Chen, J. J.

    2017-10-01

    This paper proposes a method of a symmetric optothermal microactuator (S-OTMA) directly driven by laser pulse. Based on the principle of thermal flux, a dynamic model is established describing the laser-induced optothermal temperature rise and optothermal expansion of the S-OTMA’s expansion arm. The dynamic optothermal expansion and the relationship between the expansion amplitude and laser pulse frequency are simulated, indicating that the expansion arm expands and reverts periodically with the same frequency of the laser pulse, and that the expansion amplitude decreases with the increase of laser pulse frequency. Experiments have been further conducted on a micro-fabricated S-OTMA under a laser pulse of 3.3 mW power and 2-18 Hz frequency. It is shown that the S-OTMA can periodically deflect in accordance with the same frequency of the laser pulse, with a maximum response frequency of at least 18 Hz. The maximum deflection (vibration) amplitude is measured to be 13.7 µm (at 2 Hz), and the amplitude decreases as the frequency increases. Both the theoretical model and experiments prove that the S-OTMA is capable of implementing direct laser-controlled microactuation in which only ~3 mW laser power is demanded. Furthermore, bi-directional actuation of the optothermal microactuator (such as S-OTMA) can be easily achieved by alternately irradiating either arm of the microactuator. This work may broaden the applications of the S-OTMA, as well as optothermal microactuators in MEMS/MOEMS and micro/nano-technology.

  20. 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…

  1. Cell-cell communication in the kidney microcirculation

    DEFF Research Database (Denmark)

    Sørensen, Charlotte Mehlin; von Holstein-Rathlou, Niels-Henrik

    2012-01-01

    the postglomerular vasculature. Cxs form gap junctions between neighboring cells, and as in other organ systems, the major function of Cxs in the kidney appears to be mediation of intercellular communication. Cxs may also form hemichannels that allow cellular secretion of signaling molecules like ATP, and thereby...... mediate paracrine signaling. Renal Cxs facilitate vascular conduction, juxtaglomerlar apparatus calcium signaling, and enable ECs and VSMCs to communicate. Thus, current research suggests multiple roles for Cxs in important regulatory mechanisms within the kidney, including the renin-angiotensin system...

  2. Symmetric lividity of the soles as seen in private practice.

    Science.gov (United States)

    NELSON, L M

    1956-10-01

    As seen in private practice, symmetric lividity of the soles is a relatively common condition which occurs predominantly in males in the first three decades of life.Untreated, the syndrome may persist for many years or it may be self-limiting, lasting only a few days. Occupation does not seem to be a factor predisposing to symmetric lividity of the soles. There is a high incidence of family occurrence of this condition.Any form of treatment which controls the hyperhidrosis controls the other symptoms of symmetric lividity of the soles.

  3. Experimental scheme for unambiguous discrimination of linearly independent symmetric states

    International Nuclear Information System (INIS)

    Jimenez, O.; Burgos-Inostroza, E.; Delgado, A.; Saavedra, C.; Sanchez-Lozano, X.

    2007-01-01

    We propose an experimental setup for discriminating four linearly independent nonorthogonal symmetric quantum states. The setup is based on linear optics only and can be configured to implement both optimal unambiguous state discrimination [Chefles and Barnett, Phys. Lett. A 250, 223 (1998)] and minimum error discrimination. In both cases, the setup is characterized by an optimal success probability. The experimental setup can be generalized to the case of discrimination among N linearly nonorthogonal symmetric quantum states. We also study the discrimination between two incoherent superpositions of symmetric states. In this case, the setup also achieves an optimal success probability in the case of unambiguous discrimination as well as minimum error discrimination

  4. Color symmetrical superconductivity in a schematic nuclear quark model

    DEFF Research Database (Denmark)

    Bohr, Henrik; Providencia, C.; da Providencia, J.

    2010-01-01

    In this letter, a novel BCS-type formalism is constructed in the framework of a schematic QCD inspired quark model, having in mind the description of color symmetrical superconducting states. In the usual approach to color superconductivity, the pairing correlations affect only the quasi......-particle states of two colors, the single-particle states of the third color remaining unaffected by the pairing correlations. In the theory of color symmetrical superconductivity here proposed, the pairing correlations affect symmetrically the quasi-particle states of the three colors and vanishing net color...

  5. 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...

  6. Hepatitis C virus cell-cell transmission and resistance to direct-acting antiviral agents

    DEFF Research Database (Denmark)

    Xiao, Fei; Fofana, Isabel; Heydmann, Laura

    2014-01-01

    . In contrast, the role of HCV cell-cell transmission for antiviral resistance is unknown. Aiming to address this question we investigated the phenotype of HCV strains exhibiting resistance to direct-acting antivirals (DAAs) in state-of-the-art model systems for cell-cell transmission and spread. Using HCV...... genotype 2 as a model virus, we show that cell-cell transmission is the main route of viral spread of DAA-resistant HCV. Cell-cell transmission of DAA-resistant viruses results in viral persistence and thus hampers viral eradication. We also show that blocking cell-cell transmission using host......-targeting entry inhibitors (HTEIs) was highly effective in inhibiting viral dissemination of resistant genotype 2 viruses. Combining HTEIs with DAAs prevented antiviral resistance and led to rapid elimination of the virus in cell culture model. In conclusion, our work provides evidence that cell-cell transmission...

  7. 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.

  8. Symmetric-Galerkin BEM simulation of fracture with frictional contact

    CSIR Research Space (South Africa)

    Phan, AV

    2003-06-14

    Full Text Available A symmetric-Galerkin boundary element framework for fracture analysis with frictional contact (crack friction) on the crack surfaces is presented. The algorithm employs a continuous interpolation on the crack surface (utilizing quadratic boundary...

  9. Non-symmetric localized fold of a floating sheet

    Science.gov (United States)

    Rivetti, Marco

    2013-03-01

    An elastic sheet lying on the surface of a liquid, if axially compressed, shows a transition from a smooth sinusoidal pattern to a well-localized fold. This wrinkle-to-fold transition is a manifestation of a localized buckling. The symmetric and antisymmetric shapes of the fold have recently been described by Diamant and Witten (2011), who found two exact solutions of the nonlinear equilibrium equations. In this Note, we show that these solutions can be generalized to a continuous family of solutions, which yields non-symmetric shapes of the fold. We prove that non-symmetric solutions also describe the shape of a soft strip withdrawn from a liquid bath, a physical problem that allows us to easily observe portions of non-symmetric profiles.

  10. Synthesis of symmetrical systems of discrete power functions

    Directory of Open Access Journals (Sweden)

    А. Я. Білецький

    2003-03-01

    Full Text Available The procedure of building up symmetrical matrixes, which form systems of basis digital power functions, is worked out and some peculiarities of using them for the spectral analysis of signals are discussed

  11. On the Symmetric Properties for the Generalized Twisted Bernoulli Polynomials

    Directory of Open Access Journals (Sweden)

    Kim Taekyun

    2009-01-01

    Full Text Available We study the symmetry for the generalized twisted Bernoulli polynomials and numbers. We give some interesting identities of the power sums and the generalized twisted Bernoulli polynomials using the symmetric properties for the -adic invariant integral.

  12. Estimation of Time Varying Autoregressive Symmetric Alpha Stable

    Data.gov (United States)

    National Aeronautics and Space Administration — In this work, we present a novel method for modeling time-varying autoregressive impulsive signals driven by symmetric alpha stable distributions. The proposed...

  13. Symmetrization of mathematical model of charge transport in semiconductors

    Directory of Open Access Journals (Sweden)

    Alexander M. Blokhin

    2002-11-01

    Full Text Available A mathematical model of charge transport in semiconductors is considered. The model is a quasilinear system of differential equations. A problem of finding an additional entropy conservation law and system symmetrization are solved.

  14. Optical solitons in periodically managed PT-symmetric media

    Science.gov (United States)

    Abdullaev, F. Kh.; Galimzyanov, R. M.

    2018-03-01

    The dynamics of light beams in the nonlinear optical media with periodically modulated in the longitudinal direction parity-time distribution of the complex refractive index is investigated. The possibility of dynamical stabilization of PT-symmetric solitons is demonstrated.

  15. Alignment of symmetric top molecules by short laser pulses

    DEFF Research Database (Denmark)

    Hamilton, Edward; Seideman, Tamar; Ejdrup, Tine

    2005-01-01

    Nonadiabatic alignment of symmetric top molecules induced by a linearly polarized, moderately intense picosecond laser pulse is studied theoretically and experimentally. Our studies are based on the combination of a nonperturbative solution of the Schrodinger equation with femtosecond time...

  16. Optimal [Formula: see text] -symmetric switch features exceptional point.

    Science.gov (United States)

    Lupu, Anatole; Konotop, Vladimir V; Benisty, Henri

    2017-10-16

    We consider the optimization problem of least energy-cost path in open systems that are described by non-Hermitian Hamiltonians. We apply it to find the optimal gain-loss profile for a non-uniform PT-symmetric coupler performing a binary transfer function. We bring evidence that the gain-loss profile fulfilling this requirement corresponds to a non-conventional situation where light intensity is conserved at every point along the PT-symmetric system. Besides, we find that the optimal profile corresponds to a practically important case of optical switching operation achieved with minimal amount of aggregate amplification level. We show that switching architectures using such type of gain-loss profiles are much more advantageous than conventional uniform PT-symmetric couplers in terms of gain and energy. Furthermore, this type of optimal profile turns out to be robust against fabrication imperfections. This opens new prospects for functional applications of PT-symmetric devices in photonics.

  17. The geometrical theory of diffraction for axially symmetric reflectors

    DEFF Research Database (Denmark)

    Rusch, W.; Sørensen, O.

    1975-01-01

    The geometrical theory of diffraction (GTD) (cf. [1], for example) may be applied advantageously to many axially symmetric reflector antenna geometries. The material in this communication presents analytical, computational, and experimental results for commonly encountered reflector geometries...

  18. Braneworld inflation in supergravity with a shift symmetric Kahler ...

    Indian Academy of Sciences (India)

    43

    2016-01-16

    Jan 16, 2016 ... Braneworld Inflation in Supergravity with a Shift Symmetric Kähler Potential. Article Type: Original Study. Corresponding Author: MOHAMED BENNAI. MOROCCO. Corresponding Author Secondary. Information: Corresponding Author's Institution: Corresponding Author's Secondary. Institution: First Author:.

  19. Stationary Cylindrically Symmetric Solution Approaching Einstein's Cosmological Solution

    OpenAIRE

    Iftime, M. D.

    2001-01-01

    Here we describe a stationary cylindrically symmetric solution of Einstein's equation with matter consisting of a positive cosmological and rotating dust term. The solution approaches Einstein static universe solution.

  20. Sobolev Inequalities: Symmetrization and Self Improvement via Truncation

    OpenAIRE

    Martin, Joaquim; Milman, Mario; Pustylnik, Evgeniy

    2007-01-01

    We develop a new method to obtain symmetrization inequalities of Sobolev type. Our approach leads to new inequalities and considerable simplification in the theory of embeddings of Sobolev spaces based on rearrangement invariant spaces.

  1. Estimation of Time-Varying Autoregressive Symmetric Alpha Stable

    Data.gov (United States)

    National Aeronautics and Space Administration — In the last decade alpha-stable distributions have become a standard model for impulsive data. Especially the linear symmetric alpha-stable processes have found...

  2. Hepatitis C virus cell-cell transmission and resistance to direct-acting antiviral agents.

    Directory of Open Access Journals (Sweden)

    Fei Xiao

    2014-05-01

    Full Text Available Hepatitis C virus (HCV is transmitted between hepatocytes via classical cell entry but also uses direct cell-cell transfer to infect neighboring hepatocytes. Viral cell-cell transmission has been shown to play an important role in viral persistence allowing evasion from neutralizing antibodies. In contrast, the role of HCV cell-cell transmission for antiviral resistance is unknown. Aiming to address this question we investigated the phenotype of HCV strains exhibiting resistance to direct-acting antivirals (DAAs in state-of-the-art model systems for cell-cell transmission and spread. Using HCV genotype 2 as a model virus, we show that cell-cell transmission is the main route of viral spread of DAA-resistant HCV. Cell-cell transmission of DAA-resistant viruses results in viral persistence and thus hampers viral eradication. We also show that blocking cell-cell transmission using host-targeting entry inhibitors (HTEIs was highly effective in inhibiting viral dissemination of resistant genotype 2 viruses. Combining HTEIs with DAAs prevented antiviral resistance and led to rapid elimination of the virus in cell culture model. In conclusion, our work provides evidence that cell-cell transmission plays an important role in dissemination and maintenance of resistant variants in cell culture models. Blocking virus cell-cell transmission prevents emergence of drug resistance in persistent viral infection including resistance to HCV DAAs.

  3. Symmetrical retrograde actin flow in the actin fusion structure is involved in osteoclast fusion

    Directory of Open Access Journals (Sweden)

    Jiro Takito

    2017-07-01

    Full Text Available The aim of this study was to elucidate the role of the zipper-like structure (ZLS, a podosome-related structure that transiently appears at the cell contact zone, in osteoclast fusion. Live-cell imaging of osteoclasts derived from RAW264.7 cells transfected with EGFP-actin revealed consistent symmetrical retrograde actin flow in the ZLS, but not in the podosome cluster, the podosome ring or the podosome belt. Confocal imaging showed that the distributions of F-actin, vinculin, paxillin and zyxin in the ZLS were different from those in the podosome belt. Thick actin filament bundles running outside the ZLS appeared to recruit non-muscle myosin IIA. The F-actin-rich domain of the ZLS contained actin-related protein 2/3 complex (Arp2/3. Inhibition of Arp2/3 activity disorganized the ZLS, disrupted actin flow, deteriorated cell-cell adhesion and inhibited osteoclast hypermultinucleation. In contrast, ML-7, an inhibitor of myosin light chain kinase, had little effect on the structure of ZLS and promoted osteoclast hypermultinucleation. These results reveal a link between actin flow in the ZLS and osteoclast fusion. Osteoclast fusion was promoted by branched actin elongation and negatively regulated by actomyosin contraction.

  4. Parity-time symmetric cloak with isotropic modulation

    International Nuclear Information System (INIS)

    Yang, Fan; Lei Mei, Zhong

    2016-01-01

    In this work, a different kind of parity-time ( PT ) symmetric one-way cloak is proposed. Different from conventional PT -cloak, it enjoys the property of isotropic modulation for refractive index profiles. By combining PT -symmetry with the concept of cloaking at a distance, the dilemma of realizing anisotropic modulation is removed. This combination facilitates the practical realization of PT -symmetric one-way cloak. (letter)

  5. Invariant subspaces in some function spaces on symmetric spaces. II

    International Nuclear Information System (INIS)

    Platonov, S S

    1998-01-01

    Let G be a semisimple connected Lie group with finite centre, K a maximal compact subgroup of G, and M=G/K a Riemannian symmetric space of non-compact type. We study the problem of describing the structure of closed linear subspaces in various function spaces on M that are invariant under the quasiregular representation of the group G. We consider the case when M is a symplectic symmetric space of rank 1

  6. Scattering theory for non-selfadjoint extensions of symmetric operators

    OpenAIRE

    Cherednichenko, Kirill D.; Kiselev, Alexander V.; Silva, Luis O.

    2017-01-01

    This work deals with the functional model for extensions of symmetric operators and its applications to the theory of wave scattering. In terms of Boris Pavlov's spectral form of this model, we find explicit formulae for the action of the unitary group of exponentials corresponding to almost solvable extensions of a given closed symmetric operator with equal deficiency indices. On the basis of these formulae, we are able to construct wave operators and derive a new representation for the scat...

  7. Axially symmetric domain wall in 2+1-dimensions

    International Nuclear Information System (INIS)

    Soda, Jiro; Yamanaka, Yuki.

    1991-04-01

    An axially symmetric domain wall (string) in 2+1-dimensions is investigated in the synchronous gauge. This problem is also regarded as a cylindrical symmetric domain wall (membrane) in 3+1-dimensions. Using Israel's method, we present a general solution. As a special case, a static solution is obtained which agrees with the previous result of Deser and Jackiw obtained by another method. (author)

  8. Equivalencies, Identities, Symmetric Differences, and Congruencies in Orthomodular Lattices

    Science.gov (United States)

    Megill, Norman D.; Pavičić, Mladen

    2003-12-01

    It is shown that operations of equivalence cannot serve for building algebras which would induce orthomodular lattices as the operations of implication can. Several properties of equivalence operations have been investigated. Distributivity of equivalence terms and several other 3 variable expressions involving equivalence terms have been proved to hold in any orthomodular lattice. Symmetric differences have been shown to reduce to complements of equivalence terms. Some congruence relations related to equivalence operations and symmetric differences have been considered.

  9. On the symmetric block design with parameters (153, 57, 21)

    OpenAIRE

    Rexhep Gjergji

    2009-01-01

    In this paper it is proved that:A) Up to isomorphism and duality there are exactly two possible orbital structures for a putative symmetric block design with parameters (153, 57, 21) constructed using the Frobenius group F_{17·16}B) Up to isomorphism and duality there are exactly 16 possible orbital structures for a putative symmetric block design with parameters (153, 57, 21) constructed using the collineation group G.

  10. On the symmetric block design with parameters (153, 57, 21

    Directory of Open Access Journals (Sweden)

    Rexhep Gjergji

    2009-05-01

    Full Text Available In this paper it is proved that:A Up to isomorphism and duality there are exactly two possible orbital structures for a putative symmetric block design with parameters (153, 57, 21 constructed using the Frobenius group F_{17·16}B Up to isomorphism and duality there are exactly 16 possible orbital structures for a putative symmetric block design with parameters (153, 57, 21 constructed using the collineation group G.

  11. 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

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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).

  20. 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.

  1. 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

  2. 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...

  3. 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

  4. Tight junctions: a barrier to the initiation and progression of breast cancer?

    LENUS (Irish Health Repository)

    Brennan, Kieran

    2010-01-01

    Breast cancer is a complex and heterogeneous disease that arises from epithelial cells lining the breast ducts and lobules. Correct adhesion between adjacent epithelial cells is important in determining the normal structure and function of epithelial tissues, and there is accumulating evidence that dysregulated cell-cell adhesion is associated with many cancers. This review will focus on one cell-cell adhesion complex, the tight junction (TJ), and summarize recent evidence that TJs may participate in breast cancer development or progression. We will first outline the protein composition of TJs and discuss the functions of the TJ complex. Secondly we will examine how alterations in these functions might facilitate breast cancer initiation or progression; by focussing on the regulatory influence of TJs on cell polarity, cell fate and cell migration. Finally we will outline how pharmacological targeting of TJ proteins may be useful in limiting breast cancer progression. Overall we hope to illustrate that the relationship between TJ alterations and breast cancer is a complex one; but that this area offers promise in uncovering fundamental mechanisms linked to breast cancer progression.

  5. 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.

  6. 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.

  7. 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.

  8. 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....

  9. Synthesis of C3-symmetric and C4-symmetric amino acid derivatives via Suzuki-Miyaura cross-coupling reaction.

    Science.gov (United States)

    Kotha, S; Shah, V R

    2008-06-01

    Various non-natural C(3)- and C(4)-symmetric alpha-amino acid derivatives have been synthesized via Suzuki-Miyaura cross-coupling reaction between aromatic iodides or bromide and a suitably protected DL-4-boronophenylalanine derivative.

  10. Analysis of the Symmetric and Anti-Symmetric Modes in Spoof-Insulator-Spoof Waveguides

    Science.gov (United States)

    Yang, Jie; Zhao, Maoxiong; Liu, Liang; Xiang, Hong; Han, Dezhuan

    2017-06-01

    Spoof-insulator-spoof (SIS) waveguides can support propagating modes of spoof surface plasmon polaritons (SPPs). Here, the symmetry properties and dependence of dimensionality of the spoof SPPs in SIS waveguides are studied both numerically and experimentally. The dispersions of spoof SPPs in two-dimensional (2D) waveguides are distinct from those in 3D waveguides. A cut-off frequency appears at k = 0 for the symmetric mode in the 2D structure. It is found that, from the 2D to 3D case, the dimensional dependence of the spoof SPPs in SIS waveguides is similar to the "real" SPPs in metal-insulator-metal (MIM) structures. However, their asymptotic behaviors for large k are quite different since the coupling in the direction of thickness are different for the spoof SPPs and "real" SPPs. Our results can be useful in both the physics and applications of the surface modes in the microwave regime.

  11. 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.

  12. 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.

  13. SynProt: A Comprehensive Database for Proteins of the Detergent-Resistant Synaptic Junctions Fraction

    Directory of Open Access Journals (Sweden)

    Rainer ePielot

    2012-06-01

    Full Text Available Chemical synapses are highly specialized cell-cell contacts for communication between neurons in the CNS characterized by complex and dynamic protein networks at both synaptic membranes. The cytomatrix at the active zone (CAZ organizes the apparatus for the regulated release of transmitters from the presynapse. At the postsynaptic side, the postsynaptic density constitutes the machinery for detection, integration and transduction of the transmitter signal. Both pre- and postsynaptic protein networks represent the molecular substrates for synaptic plasticity. Their function can be altered both by regulating their composition and by post-translational modification of their components. For a comprehensive understanding of synaptic networks the entire ensemble of synaptic proteins has to be considered. To support this, we established a comprehensive database for synaptic junction proteins (SynProt database primarily based on proteomics data obtained from biochemical preparations of detergent-resistant synaptic junctions. The database currently contains 2,788 non-redundant entries of rat, mouse and some human proteins, which mainly have been manually extracted from twelve proteomic studies and annotated for synaptic subcellular localization. Each dataset is completed with manually added information including protein classifiers as well as automatically retrieved and updated information from public databases (UniProt and PubMed. We intend that the database will be used to support modeling of synaptic protein networks and rational experimental design.

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

    Directory of Open Access Journals (Sweden)

    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

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

    Science.gov (United States)

    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

  16. BAG-1 enhances cell-cell adhesion, reduces proliferation and induces chaperone-independent suppression of hepatocyte growth factor-induced epidermal keratinocyte migration.

    Science.gov (United States)

    Hinitt, C A M; Wood, J; Lee, S S; Williams, A C; Howarth, J L; Glover, C P; Uney, J B; Hague, A

    2010-08-01

    Cell motility is important in maintaining tissue homeostasis, facilitating epithelial wound repair and in tumour formation and progression. The aim of this study was to determine whether BAG-1 isoforms regulate epidermal cell migration in in vitro models of wound healing. In the human epidermal cell line HaCaT, endogenous BAG-1 is primarily nuclear and increases with confluence. Both transient and stable p36-Bag-1 overexpression resulted in increased cellular cohesion. Stable transfection of either of the three human BAG-1 isoforms p36-Bag-1 (BAG-1S), p46-Bag-1 (BAG-1M) and p50-Bag-1 (BAG-1L) inhibited growth and wound closure in serum-containing medium. However, in response to hepatocyte growth factor (HGF) in serum-free medium, BAG-1S/M reduced communal motility and colony scattering, but BAG-1L did not. In the presence of HGF, p36-Bag-1 transfectants retained proliferative response to HGF with no change in ERK1/2 activation. However, the cells retained E-cadherin localisation at cell-cell junctions and exhibited pronounced cortical actin. Point mutations in the BAG domain showed that BAG-1 inhibition of motility is independent of its function as a chaperone regulator. These findings are the first to suggest that BAG-1 plays a role in regulating cell-cell adhesion and suggest an important function in epidermal cohesion. Copyright 2010 Elsevier Inc. All rights reserved.

  17. BAG-1 enhances cell-cell adhesion, reduces proliferation and induces chaperone-independent suppression of hepatocyte growth factor-induced epidermal keratinocyte migration

    International Nuclear Information System (INIS)

    Hinitt, C.A.M.; Wood, J.; Lee, S.S.; Williams, A.C.; Howarth, J.L.; Glover, C.P.; Uney, J.B.; Hague, A.

    2010-01-01

    Cell motility is important in maintaining tissue homeostasis, facilitating epithelial wound repair and in tumour formation and progression. The aim of this study was to determine whether BAG-1 isoforms regulate epidermal cell migration in in vitro models of wound healing. In the human epidermal cell line HaCaT, endogenous BAG-1 is primarily nuclear and increases with confluence. Both transient and stable p36-Bag-1 overexpression resulted in increased cellular cohesion. Stable transfection of either of the three human BAG-1 isoforms p36-Bag-1 (BAG-1S), p46-Bag-1 (BAG-1M) and p50-Bag-1 (BAG-1L) inhibited growth and wound closure in serum-containing medium. However, in response to hepatocyte growth factor (HGF) in serum-free medium, BAG-1S/M reduced communal motility and colony scattering, but BAG-1L did not. In the presence of HGF, p36-Bag-1 transfectants retained proliferative response to HGF with no change in ERK1/2 activation. However, the cells retained E-cadherin localisation at cell-cell junctions and exhibited pronounced cortical actin. Point mutations in the BAG domain showed that BAG-1 inhibition of motility is independent of its function as a chaperone regulator. These findings are the first to suggest that BAG-1 plays a role in regulating cell-cell adhesion and suggest an important function in epidermal cohesion.

  18. HUWE1 Ubiquitylates and Degrades the RAC Activator TIAM1 Promoting Cell-Cell Adhesion Disassembly, Migration, and Invasion

    Directory of Open Access Journals (Sweden)

    Lynsey Vaughan

    2015-01-01

    Full Text Available The E3 ubiquitin ligase HUWE1, deregulated in carcinoma, has been implicated in tumor formation. Here, we uncover a role for HUWE1 in cell migration and invasion through degrading the RAC activator TIAM1, implying an additional function in malignant progression. In MDCKII cells in response to HGF, HUWE1 catalyzes TIAM1 ubiquitylation and degradation predominantly at cell-cell adhesions, facilitating junction disassembly, migration, and invasion. Depleting HUWE1 or mutating the TIAM1 ubiquitylation site prevents TIAM1 degradation, antagonizing scattering, and invasion. Moreover, simultaneous depletion of TIAM1 restores migration and invasion in HUWE1-depleted cells. Significantly, we show that HUWE1 stimulates human lung cancer cell invasion through regulating TIAM1 stability. Finally, we demonstrate that HUWE1 and TIAM1 protein levels are inversely correlated in human lung carcinomas. Thus, we elucidate a critical role for HUWE1 in regulating epithelial cell-cell adhesion and provide additional evidence that ubiquitylation contributes to spatiotemporal control of RAC.

  19. 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...

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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 ...

  10. Characterization of double-loop four-Josephson-junction flux qubit

    International Nuclear Information System (INIS)

    Shimazu, Y.; Saito, Y.; Wada, Z.

    2009-01-01

    An advantage of a double-loop four-Josephson-junction (4-JJ) flux qubit is the tunability of the energy gap at a symmetry point, i.e., the point at which the double-well potential of the qubit is symmetric. The energy gap is controlled via the magnetic flux in a DC superconducting quantum interference device (DC-SQUID) loop incorporated in a 4-JJ qubit. We investigate the locus of the symmetry point in the plane of two control fluxes of the qubit, taking into account the asymmetry in the DC-SQUID, which is inevitable in practical cases. The observed positions of the qubit steps are in reasonable agreement with the calculated locus of the symmetry point. We estimate the asymmetry parameter of the DC-SQUID from this analysis.

  11. Long-range gap junctional signaling controls oncogene-mediated tumorigenesis in Xenopus laevis embryos

    Directory of Open Access Journals (Sweden)

    Brook T Chernet

    2015-01-01

    Full Text Available In addition to the immediate microenvironment, long-range signaling may be an important component of cancer. Molecular-genetic analyses have implicated gap junctions – key mediators of cell-cell communication – in carcinogenesis. We recently showed that the resting voltage potential of distant cell groups is a key determinant of metastatic transformation and tumor induction. Here, we show in the Xenopus laevis model that gap junctional communication (GJC is a modulator of the long-range bioelectric signaling that regulates tumor formation. Genetic disruption of GJC taking place within tumors, within remote host tissues, or between the host and tumors – significantly lowers the incidence of tumors induced by KRAS mutations. The most pronounced suppression of tumor incidence was observed upon GJC disruption taking place farther away from oncogene-expressing cells, revealing a role for GJC in distant cells in the control of tumor growth. In contrast, enhanced GJC communication through the overexpression of wild-type connexin Cx26 increased tumor incidence. Our data confirm a role for GJC in tumorigenesis, and reveal that this effect is non-local. Based on these results and on published data on movement of ions through GJs, we present a quantitative model linking the GJC coupling and bioelectrical state of cells to the ability of oncogenes to initiate tumorigenesis. When integrated with data on endogenous bioelectric signaling during left-right patterning, the model predicts differential tumor incidence outcomes depending on the spatial configurations of gap junction paths relative to tumor location and major anatomical body axes. Testing these predictions, we found that the strongest influence of GJ modulation on tumor suppression by hyperpolarization occurred along the embryonic left-right axis. Together, these data reveal new, long-range aspects of cancer control by the host’s physiological parameters.

  12. Optofluidic realization and retaining of cell-cell contact using an abrupt tapered optical fibre.

    Science.gov (United States)

    Xin, Hongbao; Zhang, Yao; Lei, Hongxiang; Li, Yayi; Zhang, Huixian; Li, Baojun

    2013-01-01

    Studies reveal that there exists much interaction and communication between bacterial cells, with parts of these social behaviors depending on cell-cell contacts. The cell-cell contact has proved to be crucial for determining various biochemical processes. However, for cell culture with relatively low cell concentration, it is difficult to precisely control and retain the contact of a small group of cells. Particularly, the retaining of cell-cell contact is difficult when flows occur in the medium. Here, we report an optofluidic method for realization and retaining of Escherichia coli cell-cell contact in a microfluidic channel using an abrupt tapered optical fibre. The contact process is based on launching a 980-nm wavelength laser into the fibre, E. coli cells were trapped onto the fibre tip one after another, retaining cell-cell contact and forming a highly organized cell chain. The formed chains further show the ability as bio-optical waveguides.

  13. 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 ...

  14. 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

  15. A cascaded three-phase symmetrical multistage voltage multiplier

    International Nuclear Information System (INIS)

    Iqbal, Shahid; Singh, G K; Besar, R; Muhammad, G

    2006-01-01

    A cascaded three-phase symmetrical multistage Cockcroft-Walton voltage multiplier (CW-VM) is proposed in this report. It consists of three single-phase symmetrical voltage multipliers, which are connected in series at their smoothing columns like string of batteries and are driven by three-phase ac power source. The smoothing column of each voltage multiplier is charged twice every cycle independently by respective oscillating columns and discharged in series through load. The charging discharging process completes six times a cycle and therefore the output voltage ripple's frequency is of sixth order of the drive signal frequency. Thus the proposed approach eliminates the first five harmonic components of load generated voltage ripples and sixth harmonic is the major ripple component. The proposed cascaded three-phase symmetrical voltage multiplier has less than half the voltage ripple, and three times larger output voltage and output power than the conventional single-phase symmetrical CW-VM. Experimental and simulation results of the laboratory prototype are given to show the feasibility of proposed cascaded three-phase symmetrical CW-VM

  16. Optomechanically induced absorption in parity-time-symmetric optomechanical systems

    Science.gov (United States)

    Zhang, X. Y.; Guo, Y. Q.; Pei, P.; Yi, X. X.

    2017-06-01

    We explore the optomechanically induced absorption (OMIA) in a parity-time- (PT -) symmetric optomechanical system (OMS). By numerically calculating the Lyapunov exponents, we find out the stability border of the PT -symmetric OMS. The results show that in the PT -symmetric phase the system can be either stable or unstable depending on the coupling constant and the decay rate. In the PT -symmetric broken phase the system can have a stable state only for small gain rates. By calculating the transmission rate of the probe field, we find that there is an inverted optomechanically induced transparency (OMIT) at δ =-ωM and an OMIA at δ =ωM for the PT -symmetric optomechanical system. At each side of δ =-ωM there is an absorption window due to the resonance absorption of the two generated supermodes. Comparing with the case of optomechanics coupled to a passive cavity, we find that the active cavity can enhance the resonance absorption. The absorption rate at δ =ωM increases as the coupling strength between the two cavities increases. Our work provides us with a promising platform for controlling light propagation and light manipulation in terms of PT symmetry, which might have potential applications in quantum information processing and quantum optical devices.

  17. Symmetric peace education and Unesco's potential for promoting it

    Science.gov (United States)

    Pikas, Anatol

    1983-09-01

    Peace education activities, widely contrasting and often mutually inconsistent, may be understood as constituting a dialectic in which each step is based on fundamental human reaction patterns mobilized as incentives. Although neither thesis, `Sounding the Alarm', nor anthithesis, `Identifying Causes', is adequate on its own for building peace, each is a necessary stage in development towards the synthesis, `Symmetric Peace Education'. According to this concept, peace can only be achieved through co-operation between the parties threatening or threatened by each other; and the task of symmetric peace education is to bring both sides and involved neutrals together to work out a basis of common values and joint activities while protecting the identity and integrity of all participants. On the micro-level, in schools, appropriate exercises can be designed to enable pupils to learn, from their own experiences of conflict, symmetrical and constructive habits in communication. Extension to the macro-, international, level may be achieved by representative groups of educators working together without destructive confrontation to produce common peace education packages: these would be used symmetrically by mutual agreement in countries currently rearming against each other. A different approach is proposed for bringing together groups of other professional people in `prepared, constructive confrontations' in order to reduce distrust and increase mutual understanding. The express purpose for the foundation of Unesco was to build peace; and by virtue of this mandate and the nature of its constitution, the organization is uniquely placed to promote symmetric peace education in the ways described.

  18. Homophilic Protocadherin Cell-Cell Interactions Promote Dendrite Complexity

    Directory of Open Access Journals (Sweden)

    Michael J. Molumby

    2016-05-01

    Full Text Available Growth of a properly complex dendrite arbor is a key step in neuronal differentiation and a prerequisite for neural circuit formation. Diverse cell surface molecules, such as the clustered protocadherins (Pcdhs, have long been proposed to regulate circuit formation through specific cell-cell interactions. Here, using transgenic and conditional knockout mice to manipulate γ-Pcdh repertoire in the cerebral cortex, we show that the complexity of a neuron’s dendritic arbor is determined by homophilic interactions with other cells. Neurons expressing only one of the 22 γ-Pcdhs can exhibit either exuberant or minimal dendrite complexity, depending only on whether surrounding cells express the same isoform. Furthermore, loss of astrocytic γ-Pcdhs, or disruption of astrocyte-neuron homophilic matching, reduces dendrite complexity cell non-autonomously. Our data indicate that γ-Pcdhs act locally to promote dendrite arborization via homophilic matching, and they confirm that connectivity in vivo depends on molecular interactions between neurons and between neurons and astrocytes.

  19. Heterochrony as Diachronically Modified Cell-Cell Interactions

    Directory of Open Access Journals (Sweden)

    John S. Torday

    2016-01-01

    Full Text Available Heterochrony is an enabling concept in evolution theory that metaphorically captures the mechanism of biologic change due to mechanisms of growth and development. The spatio-temporal patterns of morphogenesis are determined by cell-to-cell signaling mediated by specific soluble growth factors and their cognate receptors on nearby cells of different germline origins. Subsequently, down-stream production of second messengers generates patterns of form and function. Environmental upheavals such as Romer’s hypothesized drying up of bodies of water globally caused the vertebrate water-land transition. That transition caused physiologic stress, modifying cell-cell signaling to generate terrestrial adaptations of the skeleton, lung, skin, kidney and brain. These tissue-specific remodeling events occurred as a result of the duplication of the Parathyroid Hormone-related Protein Receptor (PTHrPR gene, expressed in mesodermal fibroblasts in close proximity to ubiquitously expressed endodermal PTHrP, amplifying this signaling pathway. Examples of how and why PTHrPR amplification affected the ontogeny, phylogeny, physiology and pathophysiology of the lung are used to substantiate and further our understanding through insights to the heterochronic mechanisms of evolution, such as the fish swim bladder evolving into the vertebrate lung, interrelated by such functional homologies as surfactant and mechanotransduction. Instead of the conventional description of this phenomenon, lung evolution can now be understood as adaptive changes in the cellular-molecular signaling mechanisms underlying its ontogeny and phylogeny.

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

    Science.gov (United States)

    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.

  1. Rescue of perfluorooctanesulfonate (PFOS)-mediated Sertoli cell injury by overexpression of gap junction protein connexin 43

    Science.gov (United States)

    Li, Nan; Mruk, Dolores D.; Chen, Haiqi; Wong, Chris K. C.; Lee, Will M.; Cheng, C. Yan

    2016-07-01

    Perfluorooctanesulfonate (PFOS) is an environmental toxicant used in developing countries, including China, as a stain repellent for clothing, carpets and draperies, but it has been banned in the U.S. and Canada since the late 2000s. PFOS perturbed the Sertoli cell tight junction (TJ)-permeability barrier, causing disruption of actin microfilaments in cell cytosol, perturbing the localization of cell junction proteins (e.g., occluden-ZO-1, N-cadherin-ß-catenin). These changes destabilized Sertoli cell blood-testis barrier (BTB) integrity. These findings suggest that human exposure to PFOS might induce BTB dysfunction and infertility. Interestingly, PFOS-induced Sertoli cell injury associated with a down-regulation of the gap junction (GJ) protein connexin43 (Cx43). We next investigated if overexpression of Cx43 in Sertoli cells could rescue the PFOS-induced cell injury. Indeed, overexpression of Cx43 in Sertoli cells with an established TJ-barrier blocked the disruption in PFOS-induced GJ-intercellular communication, resulting in the re-organization of actin microfilaments, which rendered them similar to those in control cells. Furthermore, cell adhesion proteins that utilized F-actin for attachment became properly distributed at the cell-cell interface, resealing the disrupted TJ-barrier. In summary, Cx43 is a good target that might be used to manage PFOS-induced reproductive dysfunction.

  2. Strong localization of photonics in symmetric Fibonacci superlattices

    International Nuclear Information System (INIS)

    Cheng, Y H; Tsao, C W; Chen, C H; Hsueh, W J

    2015-01-01

    Strong localization from the Fabry-Pérot-like resonances that occur in symmetric Fibonacci superlattices is presented in this study. When compared with traditional Fabry–Pérot resonators, in symmetric Fibonacci superlattices, the middle space is a variant rather than an invariant half-wavelength thickness for each resonance with different orders. In addition, the electric fields of the resonances may be located on both sides of the space layer in the superlattice, which is in contrast to those in a traditional Fabry–Pérot resonator. The electric field of the resonances is strongly localized as the generation order increases. Moreover, the group delays of these peaks increase with generation order. More strongly localized modes can be found from the symmetric Fibonacci superlattices than from the traditional Fabry–Pérot resonators, which makes the proposed structure an attractive alternative to a wide variety of optoelectronic devices. (paper)

  3. Lagrangian formulation of symmetric space sine-Gordon models

    CERN Document Server

    Bakas, Ioannis; Shin, H J; Park, Q Han

    1996-01-01

    The symmetric space sine-Gordon models arise by conformal reduction of ordinary 2-dim \\sigma-models, and they are integrable exhibiting a black-hole type metric in target space. We provide a Lagrangian formulation of these systems by considering a triplet of Lie groups F \\supset G \\supset H. We show that for every symmetric space F/G, the generalized sine-Gordon models can be derived from the G/H WZW action, plus a potential term that is algebraically specified. Thus, the symmetric space sine-Gordon models describe certain integrable perturbations of coset conformal field theories at the classical level. We also briefly discuss their vacuum structure, Backlund transformations, and soliton solutions.

  4. Decomposition of a symmetric second-order tensor

    Science.gov (United States)

    Heras, José A.

    2018-05-01

    In the three-dimensional space there are different definitions for the dot and cross products of a vector with a second-order tensor. In this paper we show how these products can uniquely be defined for the case of symmetric tensors. We then decompose a symmetric second-order tensor into its ‘dot’ part, which involves the dot product, and the ‘cross’ part, which involves the cross product. For some physical applications, this decomposition can be interpreted as one in which the dot part identifies with the ‘parallel’ part of the tensor and the cross part identifies with the ‘perpendicular’ part. This decomposition of a symmetric second-order tensor may be suitable for undergraduate courses of vector calculus, mechanics and electrodynamics.

  5. Free vibration of symmetric and sigmoid functionally graded nanobeams

    Science.gov (United States)

    Hamed, M. A.; Eltaher, M. A.; Sadoun, A. M.; Almitani, K. H.

    2016-09-01

    The objective of this paper was the investigation of vibration characteristics of both nonlinear symmetric power and sigmoid functionally graded nonlocal nanobeams. The volume fractions of metal and ceramic are assumed to be distributed through a beam thickness by sigmoid law distribution and symmetric power function. Structures with symmetric distribution with mid-plane such as ceramic-metal-ceramic and metal-ceramic-metal are proposed. Nonlocal differential Eringen's elasticity is exploited to incorporate size dependency of nanobeam. The kinematic relations of Euler-Bernoulli beam are proposed, with the assumption of a small strain. A nonlocal equation of motion of nanobeam is derived by using principle of virtual work and then discretized by finite element method to obtain numerical solution. Numerical results show the effects of the function distribution, gradient index and nonlocal parameter on natural frequencies of macro- and nanobeam. This model is helpful in the mechanical design of nanoelectromechanical systems manufactured from FGM.

  6. Symmetric spaces and the Kashiwara-Vergne method

    CERN Document Server

    Rouvière, François

    2014-01-01

    Gathering and updating results scattered in journal articles over thirty years, this self-contained monograph gives a comprehensive introduction to the subject. Its goal is to: - motivate and explain the method for general Lie groups, reducing the proof of deep results in invariant analysis to the verification of two formal Lie bracket identities related to the Campbell-Hausdorff formula (the "Kashiwara-Vergne conjecture"); - give a detailed proof of the conjecture for quadratic and solvable Lie algebras, which is relatively elementary; - extend the method to symmetric spaces; here an obstruction appears, embodied in a single remarkable object called an "e-function"; - explain the role of this function in invariant analysis on symmetric spaces, its relation to invariant differential operators, mean value operators and spherical functions; - give an explicit e-function for rank one spaces (the hyperbolic spaces); - construct an e-function for general symmetric spaces, in the spirit of Kashiwara and Vergne's or...

  7. Tourist Demand Reactions: Symmetric or Asymmetric across the Business Cycle?

    Science.gov (United States)

    Bronner, Fred; de Hoog, Robert

    2017-09-01

    Economizing and spending priorities on different types of vacations are investigated during two periods: an economic downturn and returning prosperity. Two nation-wide samples of vacationers are used: one during a downturn, the other one at the start of the recovery period. Through comparing the results, conclusions can be drawn about symmetric or asymmetric tourist demand across the business cycle. The main summer holiday has an asymmetric profile: being fairly crisis-resistant during a recession and showing considerable growth during an expansion. This does not apply to short vacations and day trips, each having a symmetric profile: during a recession they experience substantial reductions and during expansion comparable growth. So when talking about tourist demand in general , one cannot say that it is symmetric or asymmetric across the business cycle: it depends on the type of vacation. Differences in tourist demand are best explained by the role of Quality-of-Life for vacationers.

  8. Rings with involution whose symmetric elements are central

    Directory of Open Access Journals (Sweden)

    Taw Pin Lim

    1980-01-01

    Full Text Available In a ring R with involution whose symmetric elements S are central, the skew-symmetric elements K form a Lie algebra over the commutative ring S. The classification of such rings which are 2-torsion free is equivalent to the classification of Lie algebras K over S equipped with a bilinear form f that is symmetric, invariant and satisfies [[x,y],z]=f(y,zx−f(z,xy. If S is a field of char ≠2, f≠0 and dimK>1 then K is a semisimple Lie algebra if and only if f is nondegenerate. Moreover, the derived algebra K′ is either the pure quaternions over S or a direct sum of mutually orthogonal abelian Lie ideals of dim≤2.

  9. Radon transformation on reductive symmetric spaces:Support theorems

    DEFF Research Database (Denmark)

    Kuit, Job Jacob

    2013-01-01

    We introduce a class of Radon transforms for reductive symmetric spaces, including the horospherical transforms, and derive support theorems for these transforms. A reductive symmetric space is a homogeneous space G/H for a reductive Lie group G of the Harish-Chandra class, where H is an open...... thus obtained can be extended to a large class of distributions containing the rapidly decreasing smooth functions and the compactly supported distributions. For these transforms we derive support theorems in which the support of ϕ is (partially) characterized in terms of the support of RPϕ. The proof...... is based on the relation between the Radon transform and the Fourier transform on G/H, and a Paley–Wiener-shift type argument. Our results generalize the support theorem of Helgason for the Radon transform on a Riemannian symmetric space....

  10. 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....

  11. Encapsulated lipomas of the tongue in benign symmetric lipomatosis.

    Science.gov (United States)

    Ettl, Tobias; Gaumann, Andreas; Ehrenberg, Ramin; Reichert, Torsten E; Driemel, Oliver

    2009-05-01

    Benign symmetric lipomatosis (Madelung disease) is a rare disorder of unknown etiology characterized by diffuse growth of unencapsulated lipomas predominantly in the head, neck and shoulder region. Involvement of the tongue has been previously described in only five cases. A 49-year-old man with alcoholic liver cirrhosis presented with an 11-year history of benign symmetric lipomatosis complaining of increasing dysphagia, dysarthria and hoarseness. Clinical intraoral examination revealed asymmetric, globular, firm, circumscribed masses on both borders of the tongue. During surgery, the masses seemed encapsulated from surrounding muscles and could easily be extirpated. However, "satellite fat cells" became obvious, which might give rise to the development of new lipomas.

  12. Four cases of acoustic neurinoma presenting with symmetrical hearing

    International Nuclear Information System (INIS)

    Matsuyoshi, Hidetake; Minoda, Ryousei; Yumoto, Eiji

    2008-01-01

    There were 37 cases of acoustic neurinoma, diagnosed at Kumamoto University hospital from 2002 to 2006. We reported four cases of acoustic neurinoma presenting with symmetrical hearing. As for chief complaint at the initial examination, three patient had cochlear or vestibular symptoms of ear fullness, vertigo or hearing loss, one patient had only headache. All cases displayed nystagmus such as paralysis-related nystagmus or upbeat nystagmus, in addition, displayed canal paresis in the affected ear. Caloric test and nystagmus showed valuable findings for detecting acoustic neurinomas presenting with symmetrical hearing. (author)

  13. (Anti)symmetric multivariate exponential functions and corresponding Fourier transforms

    International Nuclear Information System (INIS)

    Klimyk, A U; Patera, J

    2007-01-01

    We define and study symmetrized and antisymmetrized multivariate exponential functions. They are defined as determinants and antideterminants of matrices whose entries are exponential functions of one variable. These functions are eigenfunctions of the Laplace operator on the corresponding fundamental domains satisfying certain boundary conditions. To symmetric and antisymmetric multivariate exponential functions there correspond Fourier transforms. There are three types of such Fourier transforms: expansions into the corresponding Fourier series, integral Fourier transforms and multivariate finite Fourier transforms. Eigenfunctions of the integral Fourier transforms are found

  14. Some curvature properties of quarter symmetric metric connections

    International Nuclear Information System (INIS)

    Rastogi, S.C.

    1986-08-01

    A linear connection Γ ji h with torsion tensor T j h P i -T i h P j , where T j h is an arbitrary (1,1) tensor field and P i is a 1-form, has been called a quarter-symmetric connection by Golab. Some properties of such connections have been studied by Rastogi, Mishra and Pandey, and Yano and Imai. In this paper based on the curvature tensor of quarter-symmetric metric connection we define a tensor analogous to conformal curvature tensor and study some properties of such a tensor. (author)

  15. Exploring plane-symmetric solutions in f( R) gravity

    Science.gov (United States)

    Shamir, M. F.

    2016-02-01

    The modified theories of gravity, especially the f( R) gravity, have attracted much attention in the last decade. This paper is devoted to exploring plane-symmetric solutions in the context of metric f( R) gravity. We extend the work on static plane-symmetric vacuum solutions in f( R) gravity already available in the literature [1, 2]. The modified field equations are solved using the assumptions of both constant and nonconstant scalar curvature. Some well-known solutions are recovered with power-law and logarithmic forms of f( R) models.

  16. Geometrical Inverse Preconditioning for Symmetric Positive Definite Matrices

    Directory of Open Access Journals (Sweden)

    Jean-Paul Chehab

    2016-07-01

    Full Text Available We focus on inverse preconditioners based on minimizing F ( X = 1 − cos ( X A , I , where X A is the preconditioned matrix and A is symmetric and positive definite. We present and analyze gradient-type methods to minimize F ( X on a suitable compact set. For this, we use the geometrical properties of the non-polyhedral cone of symmetric and positive definite matrices, and also the special properties of F ( X on the feasible set. Preliminary and encouraging numerical results are also presented in which dense and sparse approximations are included.

  17. Flat synchronizations in spherically symmetric space-times

    International Nuclear Information System (INIS)

    Herrero, Alicia; Morales-Lladosa, Juan Antonio

    2010-01-01

    It is well known that the Schwarzschild space-time admits a spacelike slicing by flat instants and that the metric is regular at the horizon in the associated adapted coordinates (Painleve-Gullstrand metric form). We consider this type of flat slicings in an arbitrary spherically symmetric space-time. The condition ensuring its existence is analyzed, and then, we prove that, for any spherically symmetric flat slicing, the densities of the Weinberg momenta vanish. Finally, we deduce the Schwarzschild solution in the extended Painleve-Gullstrand-LemaItre metric form by considering the coordinate decomposition of the vacuum Einstein equations with respect to a flat spacelike slicing.

  18. Possible origin of transition from symmetric to asymmetric fission

    Directory of Open Access Journals (Sweden)

    H. Paşca

    2016-09-01

    Full Text Available The charged distributions of fragments produced in the electromagnetic-induced fission of the even–even isotopes of Rn, Ra, Th, and U are described within an improved scission-point model and compared with the available experimental data. The three-equal-peaked charge distributions are predicted for several fissioning nuclei with neutron number N=136. The possible explanation of the transition from a symmetric fission mode to an asymmetric one around N∼136 is presented. The excitation energy dependencies of the asymmetric and symmetric fission modes are anticipated.

  19. Positive projections of symmetric matrices and Jordan algebras

    DEFF Research Database (Denmark)

    Fuglede, Bent; Jensen, Søren Tolver

    2013-01-01

    An elementary proof is given that the projection from the space of all symmetric p×p matrices onto a linear subspace is positive if and only if the subspace is a Jordan algebra. This solves a problem in a statistical model.......An elementary proof is given that the projection from the space of all symmetric p×p matrices onto a linear subspace is positive if and only if the subspace is a Jordan algebra. This solves a problem in a statistical model....

  20. Symmetric bends how to join two lengths of cord

    CERN Document Server

    Miles, Roger E

    1995-01-01

    A bend is a knot securely joining together two lengths of cord (or string or rope), thereby yielding a single longer length. There are many possible different bends, and a natural question that has probably occurred to many is: "Is there a 'best' bend and, if so, what is it?"Most of the well-known bends happen to be symmetric - that is, the two constituent cords within the bend have the same geometric shape and size, and interrelationship with the other. Such 'symmetric bends' have great beauty, especially when the two cords bear different colours. Moreover, they have the practical advantage o

  1. Color-symmetric superconductivity in a phenomenological QCD model

    DEFF Research Database (Denmark)

    Bohr, Henrik; Providencia, C.; Providencia, J. da

    2009-01-01

    In this paper, we construct a theory of the NJL type where superconductivity is present, and yet the superconducting state remains, in the average, color symmetric. This shows that the present approach to color superconductivity is consistent with color singletness. Indeed, quarks are free...... in the deconfined phase, but the deconfined phase itself is believed to be a color singlet. The usual description of the color superconducting state violates color singletness. On the other hand, the color superconducting state here proposed is color symmetric in the sense that an arbitrary color rotation leads...

  2. Algorithms for sparse, symmetric, definite quadratic lambda-matrix eigenproblems

    International Nuclear Information System (INIS)

    Scott, D.S.; Ward, R.C.

    1981-01-01

    Methods are presented for computing eigenpairs of the quadratic lambda-matrix, M lambda 2 + C lambda + K, where M, C, and K are large and sparse, and have special symmetry-type properties. These properties are sufficient to insure that all the eigenvalues are real and that theory analogous to the standard symmetric eigenproblem exists. The methods employ some standard techniques such as partial tri-diagonalization via the Lanczos Method and subsequent eigenpair calculation, shift-and- invert strategy and subspace iteration. The methods also employ some new techniques such as Rayleigh-Ritz quadratic roots and the inertia of symmetric, definite, quadratic lambda-matrices

  3. Interaction of non-radially symmetric camphor particles

    Science.gov (United States)

    Ei, Shin-Ichiro; Kitahata, Hiroyuki; Koyano, Yuki; Nagayama, Masaharu

    2018-03-01

    In this study, the interaction between two non-radially symmetric camphor particles is theoretically investigated and the equation describing the motion is derived as an ordinary differential system for the locations and the rotations. In particular, slightly modified non-radially symmetric cases from radial symmetry are extensively investigated and explicit motions are obtained. For example, it is theoretically shown that elliptically deformed camphor particles interact so as to be parallel with major axes. Such predicted motions are also checked by real experiments and numerical simulations.

  4. Accretion processes for general spherically symmetric compact objects

    International Nuclear Information System (INIS)

    Bahamonde, Sebastian; Jamil, Mubasher

    2015-01-01

    We investigate the accretion process for different spherically symmetric space-time geometries for a static fluid. We analyze this procedure using the most general black hole metric ansatz. After that, we examine the accretion process for specific spherically symmetric metrics obtaining the velocity of the sound during the process and the critical speed of the flow of the fluid around the black hole. In addition, we study the behavior of the rate of change of the mass for each chosen metric for a barotropic fluid. (orig.)

  5. Electrochemical gate-controlled electron transport of redox-active single perylene bisimide molecular junctions

    International Nuclear Information System (INIS)

    Li, C; Mishchenko, A; Li, Z; Pobelov, I; Wandlowski, Th; Li, X Q; Wuerthner, F; Bagrets, A; Evers, F

    2008-01-01

    We report a scanning tunneling microscopy (STM) experiment in an electrochemical environment which studies a prototype molecular switch. The target molecules were perylene tetracarboxylic acid bisimides modified with pyridine (P-PBI) and methylthiol (T-PBI) linker groups and with bulky tert-butyl-phenoxy substituents in the bay area. At a fixed bias voltage, we can control the transport current through a symmetric molecular wire Au|P-PBI(T-PBI)|Au by variation of the electrochemical 'gate' potential. The current increases by up to two orders of magnitude. The conductances of the P-PBI junctions are typically a factor 3 larger than those of T-PBI. A theoretical analysis explains this effect as a consequence of shifting the lowest unoccupied perylene level (LUMO) in or out of the bias window when tuning the electrochemical gate potential VG. The difference in on/off ratios reflects the variation of hybridization of the LUMO with the electrode states with the anchor groups. I T -E S(T) curves of asymmetric molecular junctions formed between a bare Au STM tip and a T-PBI (P-PBI) modified Au(111) electrode in an aqueous electrolyte exhibit a pronounced maximum in the tunneling current at -0.740, which is close to the formal potential of the surface-confined molecules. The experimental data were explained by a sequential two-step electron transfer process

  6. Humidity-controlled rectification switching in ruthenium-complex molecular junctions

    Science.gov (United States)

    Atesci, Huseyin; Kaliginedi, Veerabhadrarao; Celis Gil, Jose A.; Ozawa, Hiroaki; Thijssen, Joseph M.; Broekmann, Peter; Haga, Masa-aki; van der Molen, Sense Jan

    2018-02-01

    Although molecular rectifiers were proposed over four decades ago1,2, until recently reported rectification ratios (RR) were rather moderate2-11 (RR 101). This ceiling was convincingly broken using a eutectic GaIn top contact12 to probe molecular monolayers of coupled ferrocene groups (RR 105), as well as using scanning tunnelling microscopy-break junctions13-16 and mechanically controlled break junctions17 to probe single molecules (RR 102-103). Here, we demonstrate a device based on a molecular monolayer in which the RR can be switched by more than three orders of magnitude (between RR 100 and RR ≥ 103) in response to humidity. As the relative humidity is toggled between 5% and 60%, the current-voltage (I-V) characteristics of a monolayer of di-nuclear Ru-complex molecules reversibly change from symmetric to strongly asymmetric (diode-like). Key to this behaviour is the presence of two localized molecular orbitals in series, which are nearly degenerate in dry circumstances but become misaligned under high humidity conditions, due to the displacement of counter ions (PF6-). This asymmetric gating of the two relevant localized molecular orbital levels results in humidity-controlled diode-like behaviour.

  7. 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.

  8. 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

  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. 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...

  15. 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...

  16. 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.

  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. 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

  19. 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....

  20. 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.

  1. 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.

  2. 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....

  3. 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.

  4. 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

  5. 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.

  6. 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...

  7. 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.

  8. 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

  9. Gap junctions in the ovary of Drosophila melanogaster: localization of innexins 1, 2, 3 and 4 and evidence for intercellular communication via innexin-2 containing channels

    Directory of Open Access Journals (Sweden)

    Zimmermann Jennifer

    2008-11-01

    Full Text Available Abstract Background In the Drosophila ovary, germ-line and soma cells are interconnected via gap junctions. The main gap-junction proteins in invertebrates are members of the innexin family. In order to reveal the role that innexins play in cell-cell communication during oogenesis, we investigated the localization of innexins 1, 2, 3 and 4 using immunohistochemistry, and analyzed follicle development following channel blockade. Results We found innexin 1 predominantly localized to the baso-lateral domain of follicle cells, whereas innexin 2 is positioned apico-laterally as well as apically between follicle cells and germ-line cells. Innexin 3 was observed laterally in follicle cells and also in nurse cells, and innexin 4 was detected in the oolemma up to stage 8 and in nurse-cell membranes up to stage 12. In order to test whether innexins form channels suitable for intercellular communication, we microinjected innexin antibodies in combination with a fluorescent tracer into the oocyte of stage-10 follicles. We found that dye-coupling between oocyte and follicle cells was largely reduced by innexin-2 antibodies directed against the intracellular C-terminus as well as against the intracellular loop. Analyzing in vitro, between stages 10 and 14, the developmental capacities of follicles following microinjections of innexin-2 antibodies revealed defects in follicle-cell differentiation, nurse-cell regression, oocyte growth and choriogenesis. Conclusion Our results suggest that all analyzed innexins are involved in the formation of gap junctions in the ovary. While innexins 2 and 3 are colocalized between soma cells, innexins 2 and 4 are colocalized between soma and germ-line cells. Innexin 2 is participating in cell-cell communication via hemichannels residing in the oolemma. It is obvious that gap-junctional communication between germ-line and soma cells is essential for several processes during oogenesis.

  10. Symmetric Negative Differential Resistance in a Molecular Nanosilver Chain

    Directory of Open Access Journals (Sweden)

    Tae Kyung Kim

    2013-01-01

    Full Text Available The electrical transport properties of the molecular nanosilver chain have been investigated. We observed the symmetric negative differential resistance (NDR in the current-voltage characteristics. The peak voltage (VP increased but the peak current (IP decreased upon cooling. The self-capacitance effect of the silver chain crystal is suggested to explain this unconventional NDR phenomenon.

  11. Symmetrical Womanhood: The Educational Ideology of Activism at Wellesley.

    Science.gov (United States)

    Palmieri, Patricia Ann

    1995-01-01

    The ideology of higher education for women at Wellesley College in the late 19th and early 20th centuries is discussed in the context of feminism and the women's suffrage movement. "Symmetrical womanhood," a concept emphasizing balance of traditional roles and intellectual and community involvement, was a goal of Wellesley faculty of…

  12. Spectra of PT -symmetric Hamiltonians on tobogganic contours

    Indian Academy of Sciences (India)

    The term PT -symmetric quantum mechanics, although defined to be of a much broader use, was coined in tight connection with C. Bender's analysis of one- ... on the other hand, the other members of the family were strange Hamiltonians with imaginary potentials which do not appear physical at all. The aim of the.

  13. Perception of the Symmetrical Patterning of Human Gait by Infants.

    Science.gov (United States)

    Booth, Amy E.; Pinto, Jeannine; Bertenthal, Bennett I.

    2002-01-01

    Two experiments tested infants' sensitivity to properties of point-light displays of a walker and a runner that were equivalent regarding the phasing of limb movements. Found that 3-, but not 5-month-olds, discriminated these displays. When the symmetrical phase-patterning of the runner display was perturbed by advancing two of its limbs by 25…

  14. Characterizing and approximating eigenvalue sets of symmetric interval matrices

    DEFF Research Database (Denmark)

    Hladík, Milan; Daney, David; Tsigaridas, Elias

    2011-01-01

    We consider the eigenvalue problem for the case where the input matrix is symmetric and its entries are perturbed, with perturbations belonging to some given intervals. We present a characterization of some of the exact boundary points, which allows us to introduce an inner approximation algorith...

  15. Characterisation of a highly symmetrical miniature capacitive triaxial accelerometer

    NARCIS (Netherlands)

    Lotters, Joost Conrad; Lötters, Joost Conrad; Olthuis, Wouter; Veltink, Petrus H.; Bergveld, Piet

    1997-01-01

    A highly symmetrical cubic capacitive triaxial accelerometer for biomedical applications has been designed, realised and tested. The sensors are available in two outer dimensions, namely 2×2×2 and 5×5×5 mm3. The devices are mounted on a standard IC package for easy testing. Features of the sensor

  16. An invariant symmetric non-selfadjoint differential operator

    NARCIS (Netherlands)

    Thomas, Erik G.F.

    2002-01-01

    Let D be a symmetric left invariant differential operator on a unimodular Lie group G of type I. Then we show that D is essentially self-adjoint if and only if for almost all pi is an element of (G) over cap, with respect to the Plancherel measure, the operator pi(D) is essentially self-adjoint.

  17. An optimal version of an inequality involving the third symmetric ...

    Indian Academy of Sciences (India)

    An optimal version of an inequality involving the third symmetric means. WEN JIAJIN1, YUAN JUN2 and YUAN SHUFENG3. 1Department of Mathematics and Computer Science, Chengdu University,. 610106 Chengdu, China. 2School of Mathematics and Computer Science, Nanjing Normal University,. 210097 Nanjing ...

  18. Geometries and interpolations for symmetric positive definite matrices

    DEFF Research Database (Denmark)

    Feragen, Aasa; Fuster, Andrea

    2017-01-01

    In this survey we review classical and recently proposed Riemannian metrics and interpolation schemes on the space of symmetric positive definite (SPD) matrices. We perform simulations that illustrate the problem of tensor fattening not only in the usually avoided Frobenius metric, but also...

  19. Bilaterally symmetric Fourier approximations of the skull outlines of ...

    Indian Academy of Sciences (India)

    Unknown

    [Sengupta P D, Sengupta D and Ghosh P 2005 Bilaterally symmetric Fourier approximations of the skull outlines of temnospondyl amphibians and their ... The outlines of the vertebrate skulls are variable and they help in recognizing the ..... Carrol R L 1988 Vertebrate paleontology and evolution (New York: Freeman) pp 698.

  20. PEO nanocomposite polymer electrolyte for solid state symmetric

    Indian Academy of Sciences (India)

    Physical and electrochemical properties of polyethylene oxide (PEO)-based nanocomposite solid polymer electrolytes (NPEs) were investigated for symmetric capacitor applications. Nanosize fillers, i.e., Al2O3 and SiO2 incorporated polymer electrolyte exhibited higher ionic conductivity than those with filler-free composites ...

  1. Diagonalization of a real-symmetric Hamiltonian by genetic algorithm

    Indian Academy of Sciences (India)

    Unknown

    Diagonalization of a real-symmetric Hamiltonian by genetic algorithm: A recipe based on minimization of Rayleigh quotient. SUBHAJIT NANDY1, PINAKI CHAUDHURY2 and S P BHATTACHARYYA*. Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur,. Kolkata 700 032, India.

  2. Diagonalization of a real-symmetric Hamiltonian by genetic ...

    Indian Academy of Sciences (India)

    A genetic algorithm-based recipe involving minimization of the Rayleigh quotient is proposed for the sequential extraction of eigenvalues and eigenvectors of a real symmetric matrix with and without basis optimization. Important features of the method are analysed, and possible directions of development suggested.

  3. Bilaterally symmetric Fourier approximations of the skull outlines of ...

    Indian Academy of Sciences (India)

    Present work illustrates a scheme of quantitative description of the shape of the skull outlines of temnospondyl amphibians using bilaterally symmetric closed Fourier curves. Some special points have been identified on the Fourier fits of the skull outlines, which are the local maxima, or minima of the distances from the ...

  4. Symmetric/asymmetric bifurcation behaviours of a bogie system

    DEFF Research Database (Denmark)

    Xue-jun, Gao; Ying-hui, Li; Yuan, Yue

    2013-01-01

    Based on the bifurcation and stability theory of dynamical systems, the symmetric/asymmetric bifurcation behaviours and chaotic motions of a railway bogie system under a complex nonlinear wheel–rail contact relation are investigated in detail by the ‘resultant bifurcation diagram’ method with slo...

  5. Rotating cylindrically symmetric Kaluza-Klein fluid model

    Indian Academy of Sciences (India)

    Several relativistic cylindrically symmetric, non-static, inhomogeneous KK fluid models admitting dimensional reduction have been reported by Patel and Dadhich [2,3]. After Godel [4] gave relativistic model of a rotating dust universe, the study of rotating fluids in the context of general relativity received considerable attention ...

  6. 14 CFR 25.331 - Symmetric maneuvering conditions.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Symmetric maneuvering conditions. 25.331 Section 25.331 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... determining elevator angles and chordwise load distribution in the maneuvering conditions of paragraphs (b...

  7. Symmetric Dimethylarginine in Cats with Hypertrophic Cardiomyopathy and Diabetes Mellitus

    DEFF Research Database (Denmark)

    Langhorn, R.; Kieler, I. N.; Koch, J.

    2018-01-01

    Background: Symmetric dimethylarginine (SDMA) has been increasingly used as a marker of early chronic kidney disease (CKD) in cats, but little is known about the influence of comorbidities on SDMA in this species. Hypothesis: Hypertrophic cardiomyopathy (HCM) and diabetes mellitus (DM), independe...... controls, a finding that needs further investigation and should be kept in mind when evaluating renal function of cats with this endocrinopathy....

  8. Symmetrical and asymmetrical growth restriction in preterm-born children

    NARCIS (Netherlands)

    Bocca-Tjeertes, Inger; Bos, Arend; Kerstjens, Jorien; de Winter, Andrea; Reijneveld, Sijmen

    OBJECTIVE: To determine how symmetric (proportionate; SGR) and asymmetric (disproportionate; AGR) growth restriction influence growth and development in preterms from birth to 4 years. METHODS: This community-based cohort study of 810 children comprised 86 SGR, 61 AGR, and 663 non-growth restricted

  9. PT-Symmetric Waveguides and the Lack of Variational Techniques

    Czech Academy of Sciences Publication Activity Database

    Krejčiřík, David

    2012-01-01

    Roč. 73, č. 1 (2012), s. 1-2 ISSN 0378-620X Institutional support: RVO:61389005 Keywords : Robin Laplacian * non-self-adjoint boundary conditions * complex symmetric operator * PT-symmetry * waveguides * discrete and essential spectra Subject RIV: BA - General Mathematics Impact factor: 0.713, year: 2012

  10. Cylindrically symmetric cosmological model in the presence of bulk ...

    Indian Academy of Sciences (India)

    Cylindrically symmetric non-static space–time is investigated in the presence of bulk stress given by Landau and Lifshitz. To get a solution, a supplementary condition between metric potentials is used. The viscosity coefficient of the bulk viscous fluid is assumed to be a power function of mass density whereas the coefficient ...

  11. First Tests on the Symmetrical Breakwater Armor Unit Crablock

    NARCIS (Netherlands)

    Salauddin, M; Broere, A.; van der Meer, J.W.; Verhagen, H.J.; Bijl, E

    2017-01-01

    Single layer concrete armor systems are being widely used nowadays in the design of rubble mound breakwaters. Recently, a new concrete armor unit has been developed and applied as single layer armor system in the repair works of one damaged breakwater at Al Fujeirah, UAE. It has a symmetrical

  12. Symmetric approximations of the Navier-Stokes equations

    International Nuclear Information System (INIS)

    Kobel'kov, G M

    2002-01-01

    A new method for the symmetric approximation of the non-stationary Navier-Stokes equations by a Cauchy-Kovalevskaya-type system is proposed. Properties of the modified problem are studied. In particular, the convergence as ε→0 of the solutions of the modified problem to the solutions of the original problem on an infinite interval is established

  13. Rotating cylindrically symmetric Kaluza-Klein fluid model

    Indian Academy of Sciences (India)

    Kaluza-Klein field equations for stationary cylindrically symmetric fluid models in standard Einstein theory are formulated and a set of physically viable solutions is reported. This set is believed to be the first such Kaluza-Klein solutions and it includes the Kaluza-Klein counterpart of Davidson's solution describing spacetime ...

  14. Rotating cylindrically symmetric Kaluza-Klein fluid model

    Indian Academy of Sciences (India)

    Abstract. Kaluza-Klein field equations for stationary cylindrically symmetric fluid models in stan- dard Einstein theory are formulated and a set of physically viable solutions is reported. This set is believed to be the first such Kaluza-Klein solutions and it includes the Kaluza-Klein counterpart of. Davidson's solution describing ...

  15. Minimal surfaces in symmetric spaces with parallel second ...

    Indian Academy of Sciences (India)

    Xiaoxiang Jiao

    2017-07-31

    Jul 31, 2017 ... Abstract. In this paper, we study geometry of isometric minimal immersions of. Riemannian surfaces in a symmetric space by moving frames and prove that the Gaussian curvature must be constant if the immersion is of parallel second fundamental form. In particular, when the surface is S2, we discuss the ...

  16. first principles derivation of a stress function for axially symmetric

    African Journals Online (AJOL)

    HOD

    found to be identical with the Love stress function. The stress function was then applied to solve the axially symmetric problem of finding the stress fields, strain fields and displacement fields in the semi-infinite linear elastic, isotropic homogeneous medium subject to a point load P acting at the origin of coordinates also ...

  17. Bilaterally symmetrical foramina on the parietal bone of the bovine ...

    African Journals Online (AJOL)

    Different bovine skull developmental defects have been reported with variable frequency of occurrence. We hereby report a bilaterally symmetrical parietal foramina in a processed skull meant for osteological practical at the Department of Veterinary Anatomy, University of Jos, Nigeria. The depths of each of the foramina ...

  18. Entangling capabilities of symmetric two-qubit gates

    Indian Academy of Sciences (India)

    2014-07-25

    Jul 25, 2014 ... Our work addresses the problem of generating maximally entangled two spin-1/2 (qubit) symmetric states using NMR, NQR, Lipkin–Meshkov–Glick Hamiltonians. Time evolution of such Hamiltonians provides various logic gates which can be used for quantum processing tasks. Pairs of spin-1/2s have ...

  19. Coupled dilaton and electromagnetic field in cylindrically symmetric ...

    Indian Academy of Sciences (India)

    An exact solution is obtained for coupled dilaton and electromagnetic field in a cylindrically symmetric spacetime where an axial magnetic field as well as a radial electric field both are present. Depending on the choice of the arbitrary constants our solution reduces either to dilatonic gravity with pure electric field or to that ...

  20. On split Lie algebras with symmetric root systems

    Indian Academy of Sciences (India)

    , Spain. E-mail: ajesus.calderon@uca.es. MS received 24 May 2007. Abstract. We develop techniques of connections of roots for split Lie algebras with symmetric root systems. We show that any of such algebras L is of the form L = U +. ∑.

  1. A New Symmetrical Unit for Breakwater Armour : First Tests

    NARCIS (Netherlands)

    Salauddin, M.; Broere, A.; Van der Meer, J.W.; Verhagen, H.J.; Bijl, E.

    2015-01-01

    A new and symmetrical single layer armour unit, the crablock, has been designed in the UAE. One breakwater was reconstructed with crablock, but very limited testing had been performed. Just to become more acquainted with this new unit, pre-competitive research at a university has been performed,

  2. Initial value formulation for the spherically symmetric dust solution

    International Nuclear Information System (INIS)

    Liu, H.

    1990-01-01

    An initial value formulation for the dust solution with spherical symmetry is given explicitly in which the initial distributions of dust and its velocity on an initial surface are chosen to be the initial data. As special cases, the Friedmann universe, the Schwarzschild solution in comoving coordinates, and a spherically symmetric and radially inhomogeneous cosmological model are derived

  3. PEO nanocomposite polymer electrolyte for solid state symmetric ...

    Indian Academy of Sciences (India)

    Physical and electrochemical properties of polyethylene oxide (PEO)-based nanocomposite solid polymer electrolytes (NPEs) were investigated for symmetric capacitor applications. Nanosize fillers, i.e., Al2O3 and SiO2 incorporated polymer electrolyte exhibited higher ionic conductivity than those with filler-free composites ...

  4. Cylindrically symmetric cosmological model in the presence of bulk ...

    Indian Academy of Sciences (India)

    2016-09-06

    Sep 6, 2016 ... coefficient of shear viscosity is considered as proportional to the scale of expansion in the model. Also some physical and geometrical properties of the model are discussed. Keywords. Cylindrically symmetric space–time; viscous fluid; variable cosmological constant. PACS Nos 98.80.Es; 04.20.jb; 04.20.−q.

  5. Entangling capabilities of symmetric two-qubit gates

    Indian Academy of Sciences (India)

    two spin-1/2 symmetric states which belong to a subspace spanned by the angular momentum basis. {|j = 1,μ〉; μ = +1, 0, −1}. Our technique relies on the decomposition of a Hamiltonian in terms of SU(3) basis matrices. In this context, we define a set of linearly independent, traceless, Hermitian operators which provides an ...

  6. From PT-symmetric quantum mechanics to conformal field theory

    Indian Academy of Sciences (India)

    One of the simplest examples of a P T -symmetric quantum system is the scaling Yang–Lee model, a quantum field theory with cubic interaction and purely imaginary coupling. We give a historical review of some facts about this model in ≤ 2 dimensions, from its original definition in connection with phase transitions in the ...

  7. A summary view of the symmetric cosmological model

    International Nuclear Information System (INIS)

    Aldrovandi, R.

    1975-01-01

    A brief analysis of cosmological models is done, beginning with the standard model and following with the symmetric model of Omnes. Some attempts have been made for the phase transition in thermal radiation at high temperatures, to the annihilation period and to coalescence. One model with equal amounts of matter and antimatter seems to be reasonable [pt

  8. The 'core' of symmetric homogeneous polynomial inequalities of ...

    African Journals Online (AJOL)

    In this paper we explore inequalities between symmetric homogeneous polynomials of degree four of three real variables and three nonnegative real variables. The main theorems describe the cases in which the smallest possible coefficient is not expressed by the other coefficients. The problem is resolved by introducing a ...

  9. On Split Lie Algebras with Symmetric Root Systems

    Indian Academy of Sciences (India)

    ... and any I j a well described ideal of , satisfying [ I j , I k ] = 0 if j ≠ k . Under certain conditions, the simplicity of is characterized and it is shown that is the direct sum of the family of its minimal ideals, each one being a simple split Lie algebra with a symmetric root system and having all its nonzero roots connected.

  10. On split Lie algebras with symmetric root systems

    Indian Academy of Sciences (India)

    ideal of L, satisfying [Ij ,Ik] = 0 if j = k. Under certain conditions, the simplicity of L is characterized and it is shown that L is the direct sum of the family of its minimal ideals, each one being a simple split Lie algebra with a symmetric root system and having all its nonzero roots connected. Keywords. Infinite dimensional Lie ...

  11. Plane Symmetric Cosmological Model with Quark and Strange ...

    Indian Academy of Sciences (India)

    parameter. We also discussed the physical behavior of the solutions by using some physical parameters. Keywords. f(R,T) theory of gravity—plane symmetric space-time—quark and strange quark matter—constant deceleration parameter. 1. Introduction. Modern astrophysical observations point out that present expansion ...

  12. Is PT -symmetric quantum theory false as a fundamental theory?

    Czech Academy of Sciences Publication Activity Database

    Znojil, Miloslav

    2016-01-01

    Roč. 56, č. 3 (2016), s. 254-257 ISSN 1210-2709 R&D Projects: GA ČR GA16-22945S Institutional support: RVO:61389005 Keywords : quantum mechanics * PT-symmetric representations of observables * masurement outcomes Subject RIV: BE - Theoretical Physics

  13. Report on the Dynamical Evolution of an Axially Symmetric Quasar ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... The role of the angular momentum in the regular or chaotic character of motion in an axially symmetric quasar model is examined. It is found that, for a given value of the critical angular momentum , there are two values of the mass of the nucleus for which transition from regular to chaotic motion ...

  14. Plane Symmetric Cosmological Model with Quark and Strange ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Astrophysics and Astronomy; Volume 38; Issue 1. Plane Symmetric Cosmological Model with Quark and Strange Quark Matter in f ( R , T ) Theory of Gravity. P. K. AGRAWAL D. D. PAWAR. Research Article Volume 38 Issue 1 March 2017 Article ID 2 ...

  15. New algorithms for the symmetric tridiagonal eigenvalue computation

    Energy Technology Data Exchange (ETDEWEB)

    Pan, V. [City Univ. of New York, Bronx, NY (United States)]|[International Computer Sciences Institute, Berkeley, CA (United States)

    1994-12-31

    The author presents new algorithms that accelerate the bisection method for the symmetric eigenvalue problem. The algorithms rely on some new techniques, which include acceleration of Newton`s iteration and can also be further applied to acceleration of some other iterative processes, in particular, of iterative algorithms for approximating polynomial zeros.

  16. Duality, phase structures, and dilemmas in symmetric quantum games

    International Nuclear Information System (INIS)

    Ichikawa, Tsubasa; Tsutsui, Izumi

    2007-01-01

    Symmetric quantum games for 2-player, 2-qubit strategies are analyzed in detail by using a scheme in which all pure states in the 2-qubit Hilbert space are utilized for strategies. We consider two different types of symmetric games exemplified by the familiar games, the Battle of the Sexes (BoS) and the Prisoners' Dilemma (PD). These two types of symmetric games are shown to be related by a duality map, which ensures that they share common phase structures with respect to the equilibria of the strategies. We find eight distinct phase structures possible for the symmetric games, which are determined by the classical payoff matrices from which the quantum games are defined. We also discuss the possibility of resolving the dilemmas in the classical BoS, PD, and the Stag Hunt (SH) game based on the phase structures obtained in the quantum games. It is observed that quantization cannot resolve the dilemma fully for the BoS, while it generically can for the PD and SH if appropriate correlations for the strategies of the players are provided

  17. Vibrational motion in a symmetric, double minimum potential

    DEFF Research Database (Denmark)

    Spanget-Larsen, Jens

    2015-01-01

    Molecular vibrational motion in a symmetric, double minimum potential is treated by means of a quartic model potential, by reference to the tables published by Jaan Laane and the results of harmonic analyses for the stationary points. The inversion vibration of ammonia is treated in detail. - Not...

  18. Kappa-symmetric deformations of M5-brane dynamics

    NARCIS (Netherlands)

    Drummond, JM; Kerstan, SF

    We calculate the first supersymmetric and kappa-symmetric derivative deformation of the M5-brane worldvolume theory in a flat eleven-dimensional background. By applying cohomological techniques we obtain a deformation of the standard constraint of the superembedding formalism. The first possible

  19. On Meromorphic Harmonic Functions with Respect to -Symmetric Points

    Directory of Open Access Journals (Sweden)

    Al-Shaqsi K

    2008-01-01

    Full Text Available Abstract In our previous work in this journal in 2008, we introduced the generalized derivative operator for . In this paper, we introduce a class of meromorphic harmonic function with respect to -symmetric points defined by . Coefficient bounds, distortion theorems, extreme points, convolution conditions, and convex combinations for the functions belonging to this class are obtained.

  20. Report on the Dynamical Evolution of an Axially Symmetric Quasar ...

    Indian Academy of Sciences (India)

    Abstract. The role of the angular momentum in the regular or chaotic character of motion in an axially symmetric quasar model is examined. It is found that, for a given value of the critical angular momentum Lzc, there are two values of the mass of the nucleus Mn for which transition from regular to chaotic motion occurs.

  1. On split Lie algebras with symmetric root systems

    Indian Academy of Sciences (India)

    ... family of its minimal ideals, each one being a simple split Lie algebra with a symmetric root system and having all its nonzero roots connected. Author Affiliations. Antonio J Calderón Martín1. Departamento de Matemáticas, Universidad de Cádiz, 11510 Puerto Real, Cádiz, Spain. Dates. Manuscript received: 24 May 2007 ...

  2. The role of adhesion energy in controlling cell?cell contacts

    OpenAIRE

    Ma?tre, Jean-L?on; Heisenberg, Carl-Philipp

    2011-01-01

    Recent advances in microscopy techniques and biophysical measurements have provided novel insight into the molecular, cellular and biophysical basis of cell adhesion. However, comparably little is known about a core element of cell?cell adhesion?the energy of adhesion at the cell?cell contact. In this review, we discuss approaches to understand the nature and regulation of adhesion energy, and propose strategies to determine adhesion energy between cells in vitro and in vivo.

  3. An Effective Feedback Loop between Cell-Cell Contact Duration and Morphogen Signaling Determines Cell Fate.

    Science.gov (United States)

    Barone, Vanessa; Lang, Moritz; Krens, S F Gabriel; Pradhan, Saurabh J; Shamipour, Shayan; Sako, Keisuke; Sikora, Mateusz; Guet, Călin C; Heisenberg, Carl-Philipp

    2017-10-23

    Cell-cell contact formation constitutes an essential step in evolution, leading to the differentiation of specialized cell types. However, remarkably little is known about whether and how the interplay between contact formation and fate specification affects development. Here, we identify a positive feedback loop between cell-cell contact duration, morphogen signaling, and mesendoderm cell-fate specification during zebrafish gastrulation. We show that long-lasting cell-cell contacts enhance the competence of prechordal plate (ppl) progenitor cells to respond to Nodal signaling, required for ppl cell-fate specification. We further show that Nodal signaling promotes ppl cell-cell contact duration, generating a positive feedback loop between ppl cell-cell contact duration and cell-fate specification. Finally, by combining mathematical modeling and experimentation, we show that this feedback determines whether anterior axial mesendoderm cells become ppl or, instead, turn into endoderm. Thus, the interdependent activities of cell-cell signaling and contact formation control fate diversification within the developing embryo. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Well-Controlled Cell-Trapping Systems for Investigating Heterogeneous Cell-Cell Interactions.

    Science.gov (United States)

    Kamiya, Koki; Abe, Yuta; Inoue, Kosuke; Osaki, Toshihisa; Kawano, Ryuji; Miki, Norihisa; Takeuchi, Shoji

    2018-03-01

    Microfluidic systems have been developed for patterning single cells to study cell-cell interactions. However, patterning multiple types of cells to understand heterogeneous cell-cell interactions remains difficult. Here, it is aimed to develop a cell-trapping device to assemble multiple types of cells in the well-controlled order and morphology. This device mainly comprises a parylene sheet for assembling cells and a microcomb for controlling the cell-trapping area. The cell-trapping area is controlled by moving the parylene sheet on an SU-8 microcomb using tweezers. Gentle downward flow is used as a driving force for the cell-trapping. The assembly of cells on a parylene sheet with round and line-shaped apertures is demonstrated. The cell-cell contacts of the trapped cells are then investigated by direct cell-cell transfer of calcein via connexin nanopores. Finally, using the device with a system for controlling the cell-trapping area, three different types of cells in the well-controlled order are assembled. The correct cell order rate obtained using the device is 27.9%, which is higher than that obtained without the sliding parylene system (0.74%). Furthermore, the occurrence of cell-cell contact between the three cell types assembled is verified. This cell-patterning device will be a useful tool for investigating heterogeneous cell-cell interactions. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. 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.

  6. 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%.

  7. 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.

  8. 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...

  9. 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.

  10. 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

  11. 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.

  12. ‘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

  13. 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...

  14. 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...

  15. 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...

  16. 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.

  17. 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

  18. 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.

  19. Complex group algebras of the double covers of the symmetric and alternating group

    DEFF Research Database (Denmark)

    Bessenrodt, Christine; Nguyen, Hung Ngoc; Olsson, Jørn Børling

    2015-01-01

    We prove that the double covers of the alternating and symmetric groups are determined by their complex group algebras......We prove that the double covers of the alternating and symmetric groups are determined by their complex group algebras...

  20. Implications of the Cosmological Constant for Spherically Symmetric Mass Distributions

    Science.gov (United States)

    Zubairi, Omair; Weber, Fridolin

    2013-04-01

    In recent years, scientists have made the discovery that the expansion rate of the Universe is increasing rather than decreasing. This acceleration leads to an additional term in Albert Einstein's field equations which describe general relativity and is known as the cosmological constant. This work explores the aftermath of a non-vanishing cosmological constant for relativistic spherically symmetric mass distributions, which are susceptible to change against Einstein's field equations. We introduce a stellar structure equation known as the Tolman-Oppenhiemer-Volkoff (TOV) equation modified for a cosmological constant, which is derived from Einstein's modified field equations. We solve this modified TOV equation for these spherically symmetric mass distributions and obtain stellar properties such as mass and radius and investigate changes that may occur depending on the value of the cosmological constant.